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On-site Sewage Management Design Guidelines

1. Design Guidelines for On Site Sewage Management for Single Households Page 30 Byron Shire Council Doc 491166 10 INSTALLERS REQUIREMENTS Once Council Approval for the system design has been granted licensed installers shall ensure that they have been provided with both the Council stamped design plans and a copy of Council s Conditions of Approval and then follow the procedure set out below to begin the installation process Installers of irrigation systems are required to have a current trade certificate in plumbing drainage or related trade or discipline Drainage Permit All plumbers are required to obtain a drainage permit from Council prior to commencement of work on site Inspections will not be carried out unless the plumber has obtained a drainage permit from Council In order for a drainage permit to be issued by Council an approval to install the system must have been finalised with Council and a detailed irrigation design will need to have already been submitted and approved Irrigation Installations rrigation systems are to be installed by a qualified tradesman or a professional with suitable experience in irrigation installation Maintenance Reports All on site sewage management systems require regular maintenance by the home owner and periodically also by service providers in order to ensure that the system operates reliably Most AWTSs and sub surface drip irrigation systems require quarterly maintenance by
2. On Site Sewage amp Wastewater Management Strategy E2 Byron Shire Council OSMS Design Guidelines Appendix E Treatment Service Checklist 422469 Appendix E2 OSMS Treatment System Maintenance Reporting Checklist 2 Non AWTS Septic tanks sand filters reed beds Name and Contact Details of Service Provider Client Name Client Address Client Phone No Type of System Installed Components Installed AWTS sand filter etc Date installed commissioned if known Date of Service Septic Tank Service General Odours Access OK Restrictions Tank condition Size of tank Depth of sludge Needs pumping out Soundness of tank Appearance of crust Condition of inlet Condition of outlet Condition of baffles Outlet Filter Filter fitted and functioning Filter cleaned Holding Tanks Soundness of tank Alarms working Electrical system adequately housed Pumps working Reed Bed Service Gravel bed even Water level at 50mm below gravel Reeds growing well Strongly weed infested Roots removed from inlet and outlet structures Clogging problems noted fixed Condition of baffle if present Reeds thinned harvested and removed Inspection ports cleaned amp functioning Electrical system pumps alarms etc OK Effluent quality appears OK Sand Filter Service Electrical system pumps alarms etc OK Sludge built up on top of bed Filter cover OK Effluent quality appears OK Problems noted and action ta
3. Design Guidelines for On Site Sewage Management for Single Households Page 32 Byron Shire Council Doc 491166 11 GLOSSARY AND ACRONYMS Absorption absorption and or uptake of effluent into soil by gravity and capillary action Absorption area trench bed a land application system which uses soil absorption and gravity to distribute and dispose of effluent Adsorption physical or chemical attachment of substances to the surface of soil particles Aerobic Anaerobic In the presence absence of oxygen Biological break down occurs by different micro organisms adapted to the aerobic or anaerobic conditions Aerated Wastewater Treatment System AWTS an oxygenated sewage treatment process typically involving settling of solids and flotation of scum oxidation and consumption of organic matter through aeration clarification secondary settling of solids and disinfection of wastewater before irrigation Batch System a composting toilet system involving two or more alternating chambers and in which compost is produced in batches Bedroom In Byron Shire the calculations for number of persons for which an OSMS is expected to cater for is 1 5 per bedroom For the purposes of these Design Guidelines a bedroom is a room in a house which is specified on the Council approved plans as being one built for the purposes of sleeping within it Best Management Practice practices currently employed and recommended by government and indu
4. Septic reedbed Asbl nee Figure 6 Steps 5 7 Design Model Step 8 Select soil type from list box red basaltic soils based on field assessment and DLWC mapping by Morand 1994 which classifies the soil as being typical of the Rosebank ro landscape Step 9 Select Light Clay strongly structured from soil structure below system list from soil test information Step 10 Enter 0 9 for Water Table Bedrock Depth at cell ref B14 from soil test data Total Daily Flow Liday 1020 Liday N prod per capita TN production per year kg year 25 20 ke person yr N loss in treatment system TN reduced by all N loss kg year 10 08 reduction N Plant Uptake rate kg ha year P prod per person per yr Phosphorus in effluent dp key 360 ke person yt Nitrogen Report H plant uptake kg yr S Se N load exceedence STEP 10 Water Table Bedrock Depth Gn N load percolated kat N released perctexceed Buffer to Water Table Bwb Gn Time for accumulation of Pears Nitrogen area m Hydraulic area m2 Figure 7 Steps 8 10 Design Model Appendix C User Manual for OSMS Design Model Page C13 Byron Shire Council Doc 487794 Step 11 Select level bed with grass from effective rainfall list box Step 12 Select loam clay loam silt from soil texture in root zone list box it is assumed that the surrounding surface soil will be
5. Step 4 Enter property size 20000 in cell ref D5 A B C D 1 Byron OSMS Design Model Set Defaults Sir a Block size m2 2 3 4 5 En bedrooms Grp 1 6 STEP 1 Figure 5 Steps 1 4 Design Model Step 5 Select reticulated supply bore spring creek 180L p day from list 180L pp day is the predicted water use factor for this supply type where no water conservation devices are fitted and all facilities are connected to the treatment system Step 6 Select facilities water usage from list box tick all four of the facilities in the list box for Group 1 Step 7 Select treatment method from list box Septic Reed bed Appendix C User Manual for OSMS Design Model Page C12 Byron Shire Council Doc 487794 E F G H I sic 5 Daily effluent flow accord water supp STEP 6 l Reticulated suppl i Reticulated std water saving devices 145L p d eae ke Toilet Toilet oof water harvesting p Roof water harvesting std water sav 115L p d Bathroom _ Bathroom Laundry Laudes w FS Win black to tot WW in a full system SE Kitchen _ Kitchen 7 32 STEP 7 black to tot WW i g linafull system TN 70 ec primary teatment only N loss in disposal bed Septic single pass sandfilter SPF Current Inlet BOD 9 reduction 20 Septic SPF 25 septic return flow conc 160 mg L z g 8 il 10
6. The following principles underpin Council s Design Guidelines for On site Sewage Management for Single Households Selection of a treatment system and land application area begins with consideration of the health and sensitivity of the down stream catchment and the cumulative impact to which the subject OSMS is contributing Low tech gravity fed systems are encouraged as these tend to be cheaper and more sustainable provided that effluent can be reliably and evenly distributed over a sufficiently broad area to enable adequate evapo transpiration Maximise the opportunity for nutrient and water re use by vegetation uptake Re use by evapotranspiration is the preferred method of managing post treatment nutrients Prevent off site movement of effluent via surface runoff lateral subsurface seepage or percolation into ground water Minimise the risk to householders and the public of contact with pathogenic microorganisms Distribute effluent evenly throughout the effluent application area Minimise the quantity of natural resources utilised in construction including energy Design Guidelines for On Site Sewage Management for Single Households Page 2 Byron Shire Council Doc 491166 Ensure that on site sewage management systems are to be designed and installed by a suitably qualified and experienced person with demonstrated expertise in on site sewage management issues Experience shows that there is no standa
7. Select Water Supply Reticulated std water saving devices 145L p d Roof water harvesting 140L p d Roof water harvesting std water sav 115L p d Step 6 Select Facilities Water Usage zt M Toilet select or deselect each checkbox gt Bathroom Laundry St Kitchen Septic primary teatment onl AWTS Septic single pass sandfilter SPF Septic SPF 25 septic return flow Septic recirculating sandfilter Septic reedbed Select soil type from list box red basaltic soils Morand soil map Step 9 Enter depth to water table at cell ref M35 known to be greater than 3m in this case therefore enter 3 Step 10 Select soil structure below system from list box clay loam high mod structure from soil test information E E G Step 8 Select Soil Type Morand Step 9 Enter Depth To Water Table Step 10 Select Soil Texture amp Structure Below System Figure 3 Steps 8 10 Designer Input Sheet Alluvial Soils 1 GE 10 000 kolbaim Alluvial Soils 2 cr 2 000 Red Basaltic Soils deg ew mb ro wo 10 000 ka ha m Duplex Soils ba bi bu mi ni 8 000 kg ha m Podzol Soils ab bo br eb fh ki ku og poty wy 1 000 kg ha m Gravels Sands Ksat gt 3 0 Sandy loams weakly structured Ksat gt 3 0m Sandy loams massive Ksat 1 4 3 0m Loams high moderate structured Ksat 1 5 3 0m i Loams weakly structured
8. gt 75 Heavy clay can be moulded into rods without fracture firm resistance to ribboning shear 5 2 2 Soil Structure The soil structure is to be determined from visual assessment of the site and from borehole testing through the examination of exposed soil surfaces structures Table 4 summarises the common soil Design Guidelines for On Site Sewage Management for Single Households Page 13 Byron Shire Council Doc 491166 Table 4 Soil structure according to degree of pedality Source AS NZS1547 2000 Degree of Pedality Appearance Massive Coherent with any partings both vertically and horizontally spaced at greater than 100 mm Pieces do not break along planes of weakness but break according to stress loads Single grained Loose incohesive structureless e g sands Weak Peds indistinct and barely observable on pit face When disturbed approximately 30 consist of peds smaller than 100mm Moderate Peds well formed and evident but not distinct in undisturbed soil When disturbed 30 60 consists of peds smaller than 100mm Strong Peds quite distinct in undisturbed soil When disturbed gt 60 consists of peds smaller than 100mm 5 2 3 Soil Permeability Determination Accurate soil permeability assessment is encouraged but is often quite problematic A preferred method for field evaluation using a constant head permeameter is provided in Appendix 4 1 F of AS NZS1547 2000 Al
9. land application area required for soil plant N removal 10 000 conversion factor from Ha to m Nereat dwelling N output minus any removal during treatment kg yr Noenit soil N denitrification capacity default 20 of TN after treatment Nerop annual crop N uptake capacity kg ha Byron Shire Council BSC has followed the example of Lismore Shire Council LSC and acknowledged that using the above equation produces large and therefore costly land application areas To reduce the requirement for these large areas BSC accepts that domestic OSMSs in rural areas of low development density present much lower risks to the broader environment because of the additional assimilative effluent polishing capacity of the lands surrounding the land application area Consequently the equation has been re arranged to reflect a relaxation of minimum disposal area sizes in low density well buffered developments to include a nitrogen release to the environment factor This factor currently set at a maximum of 10 kg TN yr in the Byron OSMS Design Model based conservatively on work done by Hornsby Shire Council HSC 1994 is calculated and applied according to block size The equation for the nitrogen release factor is Nim Nra exp KB ni SEN ae are Algae al ie Eqn 3 Where Niim the allowable TN release export for the system kg yr Nmax the maximum annual allowable TN release per household currently 10kg yr curv
10. addition of proprietary bacteria supplements is permitted and encouraged These proprietary bacteria can assist by reducing the amount of sludge build up and therefore increasing the time between the pumping out of the tank and by reducing the smell of the tank Appendix A to Design Guidelines Treatment Systems Page A2 Byron Shire Council OSMS Design Guidelines Appendix A 487879 Induct vents are no longer considered desirable on septic tanks due to these structures allowing flies and mosquitoes to breed in the tank E amp HP Guidelines 1998 For larger septic tank size gt 3000L grease traps are no longer required Smaller grease traps are not recommended as they need to be maintained often and have sometimes been found to be too small to trap grease effectively Kitchen wastewaters can be connected directly into an appropriately sized septic tank with a baffle installed E amp HP Guidelines 1998 Where it is absolutely necessary for some reason to use a smaller septic tank consideration should be given to installation of a suitably sized grease trap The Australian Standard for septic tanks is AS1546 1998 All septic tanks need to be manufactured in accordance with this standard and have an appropriate AS Standards Mark While alternate tank shapes are mentioned in the standard in the Tweed Richmond region the only types widely available off the shelf are cylindrical tanks Cast in situ tanks are specified in Section
11. device Effluent must be disinfected prior to the dripper system and be designed and installed by a suitably qualified person in accordance with AS NZS1547 2000 recommendations Care and maintenance requirements are provided in Appendix G Appendix B Land Application Systems Page B6 Byron Shire Council Doc 487794 Design Guidelines for On site Sewage Management for Single Households APPENDIX C User Manual for the Byron OSMS Design Computer Model Appendix C User Manual for OSMS Design Model Page C1 Byron Shire Council Doc 487794 C1 Introduction As an adjunct to Byron Council s On site Sewage System OSMS Management Design Guidelines for Single Households a computer model has been developed to assist in estimating appropriate size for effluent application fields based on expected loads proposed treatment methods and the local site and soil characteristics The Byron OSMS Design Model was originally developed for Lismore City Council by Greg Alderson amp Associates and has been reworked for Byron Shire Council by Antony McCardell and David Bonner Byron Council recommends that the OSMS Design Model be used for the estimation of application field size Alternatively the State Government guidelines E amp HP 1998 offer a more simplistic monthly water balance model to determine appropriate size for effluent application fields if preferred or any other design will be accepted if sufficient scientific justification
12. Design Guidelines in conjunction with the associated OSMS Design Model or an equivalent will enable home owners to be confident that they will not be causing pollution by allowing excess nutrients to leave their property boundaries or enter waterways In most cases this is achieved by matching the likely loads with plant uptake rates and sizing the land application area LAA to ensure complete reuse within that LAA On larger blocks where the cumulative risks of OSMS are lower Council s OSMS Design Model permits a proportional reduction of the LAA with the expectation that the buffering capacity of the vegetated lands surround the LAA will assist in assimilating any excess nutrients refer Appendix C 4 2 2 Pathogens in Sewage Pathogens are micro organisms that can cause diseases including bacteria protozoa viruses and helminths Pathogens are found in varying concentrations in all domestic sewage but are found in particularly high concentrations when one of more of the residents are infected with a disease Design Guidelines for On Site Sewage Management for Single Households Page 6 Byron Shire Council Doc 491166 Similarly if pathogens are transmitted they might have no effect on a healthy adult but can be much more of a risk for small children or immunity suppressed receptors Another related point to note is that OSMSs servicing those who are taking strong medication e g antibiotics and chemotherapy drugs are liable to be aff
13. Field pH The pH of a soil can alter the availability of nutrient elements for plant uptake and can cause metal toxicities if pH is too low or too high Acid soils tend to be leached of major plant nutrients e g calcium magnesium nitrogen and possibly molyodenum while phosphorus may not be present in plant available form Alkaline soils are often deficient in iron manganese copper or zinc Morand 1994 A field pH test using a calibrated field instrument or colour test strips should be undertaken to determine the acidity alkalinity of the soils Soil pH of between 6 5 to 8 is ideal for plant uptake of phosphorous potassium and nitrogen 5 2 7 Dispersive Class Modified Emerson Aggregate test The Modified Emerson Aggregate test provides a simple field assessment of a soil s aggregate stability It is carried out using effluent or a prepared solution with similar qualities as the effluent to be applied to the soil being tested for septic tank effluent this is equivalent to a solution with Sodium Absorption Ratio SAR of 5 and EC around 1000 uS cm Patterson 1998 The test involves placing about three 5mm diameter undisturbed soil aggregates from the soil profile into a beaker of the above solution and leaving undisturbed for 24 hours The behavior of the aggregates is then recorded from the following Class 1 Material disperses completely Class 2 Aggregates disperse clouds solution appreciably Class 3 Aggregates slake sma
14. Texture Claseiteaton 12 5 227 Soil Structure EE 13 5 2 3 Soil Permeability Determination ccccceccceeceeeeeeeeceeeeeeaeeeeaaeeeceeeesaaeeeeaaeseeeeeseaeessaeeesaeeeeeees 14 5 2 4 Colour Description 22 ccaveit edie iy ieee ited edd ge 14 5 2 5 Assessment of Coarse Fragments nnt 14 5 2 6 Field pH EE EEN 15 5 2 7 Dispersive Class Modified Emerson Aggregate test c ccccsceceeeceseeeeeeneeseeeeeseaeeeseaeeeeenees 15 5 3 Site Constraints and Possible SolutionS sssenssensseunnsunnnnunnnnnnnnnnnnnnnnnnunnnnnnnnnnnnnnnnnnnn nn 15 6 CHOOSING A TREATMENT SYSTEM ccccssccssseeeeseeseeeseseeeenseeeeeaeseseeeenseeesseeesaesaaneeeeeeeeseaeseseeeenseeeess 18 Dk SOUFCS COMMU ET secs ee hits he ates cated cae east hah eels ctl clea eat ca 18 6 1 1 Water Saving EE 18 6 1 2 Waterless Compost Toilets 0 cccccccccceceeeceeeeeceeeeeceeeeecaaeeeseaeeseaeeeeeaeeesaaesdeneeseaeeesaeeseaaeseneees 18 6 25 le EN E E EE 19 N SSptiG iT EE 19 EEN EE 19 612 39 sEffluent EE 19 6 3 Secondary A Partial Secondary Treatment cccscseeeeeeeseeeeeeeeseeeeeeeeeeneeeeeneeeeeeeeneeeeees 20 6 3 1 Aerated Wastewater Treatment Systems WT 21 Ee Sand Filters tisk i ai nea ee ees ial eG ed ta a ea eee 22 6 3 3 Subsurface Flow Reed Beds Constructed Wetande 22 6 4 T rti ry TreatMent euer eeerhde Geesse Eed 22 GE ND RE EE 22 6 5 VEER ele 23 6 5 1 Maximisation of Effluent Take up by Plate 23
15. This section describes some of the constraints and possibilities in relation to each of these elements macrophytes eee Swivel pipe level control inlet Outlet box LC D D I WT ENE NANA a ie PRE Ss SC connector Large stones Impermeable inlet amp outlet structures ee full bed width ae Removable end Caps Figure A5 Elevation and plan views of a simplified reed bed showing major components A4 3 Containment Device Liner The purpose of the reed bed liner also termed skin or under skin is to prevent the loss of wastewater and the penetration of macrophyte roots from the bed while excluding surface water groundwater adjacent soil and weeds It therefore needs to be impermeable durable and resistant to penetration by macrophyte roots Materials that have been used on the NSW North Coast include fabricated reinforced concrete slabs ferro cement stainless steel polyethylene cattle troughs fibreglass troughs sealed concrete blocks laid on concrete slab and flexible liner membranes Of these problems have been frequently encountered getting good seals in stainless steel bases and many more problems have been found sealing and maintaining the integrity of light weight flexible plastic liners Moulded polyethylene troughs are available on the market in a number of sizes and are considered highly suitable for reed bed and sand filter liners due to their robustness and ease of maintaining a seal on t
16. and demarcating inlet and outlet structures limiting the clogging growth of reed roots into the structures A4 9 Reed bed shape Having determined the total area of the bed or beds using Table A2 or the OSMS Design Model the next step is to decide on its actual shape Rectangular plans while not always the most aesthetically pleasing will be more hydraulically efficient less likely to have dead zones than curved configurations Aspect ratios length to width for rectangular beds of 3 1 down to 1 1 i e square are generally favoured in the literature The wider the bed the less likely it is to clog On sloping ground a long thin bed may be desirable for structural reasons In such cases a longer section of large stones should be installed at the front end of the bed Where multiple tubs are to be used to provide sufficient reed bed size designers have a choice to place the tubs in parallel or series Parallel options are generally preferred but require a reliable means of distributing effluent evenly e g with tipping buckets Placing one tub after another in series may be an acceptable alternative but designers must include hydraulic calculations to confirm that the hydraulic loads can be handled by the first tank noting that this same first tank is liable to clog due to the higher sedimentation and nutrient loads that it is likely to accept A5 Waterless Compost Toilets Dry composting toilets may be either constructed individually o
17. be located below the bottom point in each field If return lines are to be provided to the septic tank they must be inserted below the crust level so as not to disturb the crust gt Discharge rates from emitters should be matched to the permeability of the soil gt Pump out volumes shall be sufficient to charge pipe system for durations of between 15 and 30 minutes twice to four times per day Maintenance requirements for SDI systems including annual maintenance checks are provided in Appendix G B4 2 SURFACE SPRAY IRRIGATION Within the Byron Shire the use of surface spray irrigation even of disinfected effluent is discouraged due to public health risks NSW Health and the much higher risks of uncontrolled run off of effluent or effluent contaminated rainfall Consideration for surface spray irrigation will be given for those on site systems on large acreage where the dispersal area is a considerable distance from dwellings Other possible applications might be for flat sites on heavy clay soils provided that sufficient isolation from residents and neighbours can be demonstrated The system must be designed in accordance with AS NZS1547 2000 recommendations and installed by a suitably qualified person refer Appendix G for care and maintenance requirements If used above ground irrigation should be by heavy droplet sprinklers placed in soil conditioned garden beds with appropriate warning signs to keep children and others away Detail
18. chlorine should be considered in these cases Other ways to avoid this problem is to use non drain emitters or emitters which release miniscule doses of poison to prevent root intrusion and reduce biomass production in the immediate vicinity of the emitter e g Wasteflow Netafim Some AWTSs include an activated sludge process that enables the breakdown of sludge and a theoretically better effluent quality without the need for periodic de sludging The aerated section of the AWTS oxidises the wastewater and organic matter is consumed A clarification process is carried out through secondary settling of solids All AWTSs are accredited by the NSW Health Department pursuant to Clause 43 1 of the Local Government Approvals Regulations 1999 The AWTS must be installed in accordance with their accreditation conditions issued by NSW Health Inlet from house To pump and land application area SES ES Disinfection eturn Chamber Figure A2 Cross Section of an AWTS When functioning correctly AWTS provide a significantly higher level of treatment than simple septic tanks The Byron OSMS Design model assigns a nitrogen reduction capacity of 20 to AWTS s Appendix A to Design Guidelines Treatment Systems Page A4 Byron Shire Council OSMS Design Guidelines Appendix A 487879 A3 Sand Filters Sand filtration systems typically consist of one or more layers of sand or fine gravel contained within an impermeable structure a
19. components year flood contour must be out of 1 100 year flood Flooding Potential OR zone consider SDI with wet Treatment system below 1 in 100 year weather storage or raised flood contour application area e g mounds If due to shading trim trees or find Site Drainage Signs of surface dampness alternative area If due to stormwater adjust surface drainage Swales or diversion drains to Vegetation indicating Presence of sedges etc that indicate control drainage improve waterlogging waterlogged soil treatment expand application area or use raised mounds Surface Condition Bare ground or cracking ee solls Attempt to find alternative area or replace fill with stable compacted Land application area contains fill mixture of sand and clay soil Ensure geotechnical stability will not be compromised by effluent Promote vegetation growth Erosion Mass Movement Rills slips improve drainage get geotechnical advice The following table provides a summary of common soil problems which may be encountered in Byron Shire with an indication of when the soil characteristic may limit on site effluent dispersal and possible amelioration measures for constrained land application areas Enhanced treatment of effluent expand land application area ensure that drainage is diverted around land application area Design Guidelines for On Site Sewage Management for Single Households Page 16 Byron Shire Council Doc 491166 Table 7
20. do not substantially reduce nitrogen and the Byron OSMS Design Model does not therefore allocate any nitrogen reduction in its calculations for septic only systems In all but greywater only systems partial secondary treatment will usually be required after primary treatment in septic tanks Advice on care and maintenance of septic and sullage tanks is provided in Appendix G A1 1 Effluent Filters An effluent filter is a simple plastic filter which is fitted into the outlet of the septic tank Effluent filters are used to reduce the potential carry over of suspended solids This will improve the efficiency and longevity of the land application system or secondary treatment device It should be noted that an effluent filter does not provide partial secondary treatment of the effluent Types of effluent filter successfully used in the Byron area include Biotube Taylex Zoeller and Zabel filters It is recommended that the effluent filter should be of a robust type and preferably fitted to the outside of the tank so that owners do not have to place their hands in the tank and for ease of maintenance One means of doing this is by fitting a U trap on the outlet another is to Appendix A to Design Guidelines Treatment Systems Page A3 Byron Shire Council OSMS Design Guidelines Appendix A 487879 install a type of filter that can be cleaned by jetting water through it whilst still in place using a suitable hose attachment
21. i e a hose wand A2 Aerated Wastewater Treatment Systems AWTSs Aerated wastewater treatment systems AWTSs provide a relatively simple solution to OSMS selection These systems are scaled down sewage treatment plants and usually include both anaerobic and aerobic zones and a number of pumps AWTSs typically settle solids and float scum in an anaerobic chamber much like a septic tank and then aerate the effluent in a second chamber Figure A2 The aerobic process usually consists of injecting compressed air into the effluent to promote the growth of aerobic bacteria for treatment Failure or a sustained interruption in any part of the system e g as a result of power interruptions or when a tourist dwelling is unoccupied during the off season can lead to a period of poor treatment performance until sufficient micro organisms are once again restored to adequately treat the effluent Disinfection in AWTS is generally required as part of NSW Health s accreditation procedures and usually consists of chlorination in the final collection chamber Byron Shire Council is aware that some people choose not to disinfect their effluent in subsurface applications and agree that this is largely a matter of choice and warranty obligations Homeowners should be aware that sub surface emitters may tend to get blocked if high nutrient loads cause a build up of biomat in the soil pores surrounding the emitters and that at least periodic dosing of
22. if required will be town tanker deliveries The main home as well as the studio will connect all domestic water using facilities to the treatment system The property owners regard the plentiful bore water supply as sufficient to service both the main dwelling and studio at a rate to suit their needs without the installation of water conservation measures or appliances Soil sampling revealed a shallow 0 9m to weathered parent material stony red brown well structured clay loam on the upper slopes Changes in the soil profile are gradual but reveal a strongly structured light clay 0 45m below the surface Sedges growing in down slope pockets indicate intermittent water logging The soil of the surrounding area is shallow and boulder strewn but well structured red and brown krasnozem on basalt parent material The soil is classified by Morand DLWC 1994 as soil unit Rosebank ro A permanent creek runs along the south easterly boundary approximately 75m from a likely wastewater land application area After discussing the situation with the client the consultant s recommended wastewater treatment is to be septic secondary sized reed bed followed by subsurface drip irrigation to distribute the final treated effluent Method Starting at the top of the Design Model worksheet blue tab the development details are entered in the appropriate cell reference or selected from list boxes in a series of clearly identified steps Pre
23. maintenance or de sludging The rocks 50 100 mm around the inlet reduce clogging and allow easy access for maintenance and removal of intruding roots A4 7 Outlet Structure A simple outlet structure design incorporates a PVC pipe spanning the reed bed width and drilled with holes of approximately 15 mm diameter and surrounded by larger stones up to 100 mm Figure A5 shows an outlet structure option consisting of a series of 150 mm diameter capped vertical towers spaced evenly across the width of the bed Effluent enters the towers via 15 25 mm diameter holes surrounded by stones gt 50 mm diameter Access to the towers is available should clogging of the holes occur The reed bed is connected to an outlet box containing a device such as a swivel pipe which can be used to adjust the water level in the reed bed A series of variable length stand pipes can achieve the same result In this way the wetland can be temporarily flooded to help control terrestrial weeds during establishment If doing so extreme care should be taken to avoid contact with the effluent by people and pets Controlled water level lowering can encourage downward root penetration promoting oxygenation of the lower level of the bed and thereby enhancing treatment at that level Being able to lower the water level may therefore be useful for maintenance or repair work if required in the future A4 8 Baffles Baffles can improve reed bed designs by lengthening flow paths
24. new sand filter installations An optimal media in sand filtration systems is one in which abundant surface area for microbial growth is combined with adequate pore space to facilitate the movement of water and oxygen through the filter If the sand filter media is too coarse wastewater percolates rapidly through the system without allowing sufficient time for the pollutants to undergo treatment On the other hand if the filter media is too fine pore spaces between the particles easily clog reducing hydraulic conductivity and oxygen transfer rates It should be noted that not all of the washed coarse sand available from local suppliers on the North Coast is suitable for use in sand filters in some cases it will require additional washing and grading Sand media used in filters may be characterised through its effective size ES and uniformity coefficient UC Equations 1 and 2 ES dho 1 UC Geld 2 where ES effective size of sand UC uniformity coefficient of sand dio screen size through which no more than 10 by weight of the sand passes deo screen size through which no more than 60 by weight of the sand passes US EPA 1999 recommends that media have ES gt 0 25mm and lt 0 75mm and UC lt 4 0 Lienard et al 2000 concur with these specifications for media and add that fines lt 80 um should not exceed 3 by weight Containment of the substrate can be achieved using a variety of materials Byron Council recomm
25. or massive Ksat 0 5 1 5mjc Clay loams high mod structured Ksat 0 5 1 Smile Clay loams weakly structured Ksat 0 12 0 5m Clay loams massive structured Ksat 0 06 0 12mjc Light clays strongly structured Ksat 0 12 0 5mjc Light clays moderately structured Ksat 0 06 0 12mjc Light clays weak structured or massive Ksat lt 0 06m Med to heavy clays strong struct Ksat 0 06 0 5m Med to heavy clays mod structured Ksat lt 0 06m Med to hvy clays weak struct or massive Ksat lt 0 06m DISPERSIVE soil Modified Emerson Aggregate test Appendix C User Manual for OSMS Design Model Page C9 Byron Shire Council Doc 487794 Step 11 Select dispersal area slope type from list box level bed with grass this refers to the irrigation design for the orchard area Step 12 Select soil texture in root zone from list box loam clay loam silf it is assumed that the surrounding surface soil will be used Step 13 Select land application type from list box SSTP subsurface irrigation of the banana planting Step 14 Click on the Calculate button This will transfer the information to the Design Model sheet and within a few seconds a minimum land application area 490 m will appear in the box below the calculate button Step 15 The print button at the bottom of the page allows the full list of parameters that have been entered into the model to be print
26. or occupiers must now nominate a designated person to apply to operate the sewage management system associated with the residence or activity on the land owned or occupied by them An approval to operate requires the operator to take all reasonable steps to prevent transmission of disease and spread of foul odours pollution of water and degradation of land any discharge to a watercourse and Appendix G to Design Guidelines System Management Plan Page G9 Byron Shire Council OSMS Design Guidelines Appendix G 487883 any discharge to land other than the approved effluent application area that may occur as a result of on site sewage management activities Council approval to operate a system of sewage management is personal and does not run with the land It is the activity of sewage management not the facilities which is the subject of the approval The approval process establishes a relationship between Council and the owner to improve awareness of environmental and health risks and also the maintenance and operating requirements for their system Over 3 000 on site systems were registered in 2001 2002 and when affected properties have changed ownership the new owners have been requested to reapply for an updated Approval to Operate Anyone who owns a dwelling which is not connected to a reticulated town sewerage system is required to apply immediately for an Approval to Operate that system For mor
27. remove the black water component by installing a composting toilet This option would achieve a reduction from 443m to 379m Note also that the implications of various reed bed sizes on required application areas can be investigated in the Design Model worksheet by inserting suggested values in the macro box from H14 to 115 Appendix C User Manual for OSMS Design Model Page C14 Byron Shire Council OSMS Design Guidelines Appendix D 487906 Design Guidelines for On site Sewage Management for Single Households APPENDIX D Native local plants suitable for Land Application Areas Appendix D to Design Guidelines Plants suitable for land application areas Page D1 Byron Shire Council OSMS Design Guidelines Appendix D 487906 Native local plants suitable for Land Application Areas The following list of plants is a selection of native plants that would be suitable to be grown in or around the edges of most land application areas in Byron Shire Council does not require that plants are selected exclusively from the following list nor does it require that plants used in OSMS land application areas must be exclusively natives or native to the region though for the sake of maintaining biodiversity in the shire Council does support the use of any local natives which are able to super accumulate nitrogen and phosphorus into luxury growth Plants to be specifically avoided are those which are best grown on sand or san
28. required in their design and installation to ensure that effluent is soread evenly over the entire bed space Design Guidelines for On Site Sewage Management for Single Households Page 24 Byron Shire Council Doc 491166 Owners of ETA beds should maintain appropriate vegetation on the beds Mowed grass is the preferred vegetation cover although shrubs and trees can be planted suitable distances away from the edge of ETA beds see Appendix B3 for details 7 3 SUB SURFACE DRIP IRRIGATION SDI Sub surface drip irrigation SDI also commonly referred to as sub surface irrigation SSI is a good means of distributing treated effluent because it can distribute small measured doses to evenly spaced centres in relatively undisturbed soil This ensures a very reliable distribution available for rapid root uptake and minimises the risk of the irrigation field becoming saturated during extended rainfall Sub surface irrigation is particularly appropriate where there are site or soil limitations or limitations such as steep slopes on heavy impermeable often termed puggy soils and can even be used with care on highly permeable sandy soils Sub surface irrigation systems must be designed and installed by suitably qualified persons and must be flushed to remove sediment slime at least once per year and preferably quarterly by a qualified professional as part of the maintenance requirements Suitably located pressure release valves and f
29. the principles and requirements set out in these Design Guidelines The OSMS Design Model which comprises a 3 megabyte file in a Microsoft Excel Workbook in 3 spreadsheets is available for free download on Council s website www byron nsw gov au or for a cost recovery fee on CD Rom from Council s offices in Mullumbimby The model s theory and operation are described in Appendix C User Manual for Byron OSMS Design Model Designers will also soon be able to apply to Council for a copy of a more comprehensive document which describes how the Design Model works and how default parameters have been derived In essence Byron Shire Council s philosophy for land applications areas is to make them big enough to ensure that the treated effluent will have sufficient opportunity for plants within the area to take up all of the water and all of the nutrients applied Council s OSMS Design Model deliberately includes some risk based allowances for nitrogen for example increasing the required land area where systems are built close to creeks and reducing the required land area where systems are built on very large blocks in which the vegetated areas around the land application area can be safely assumed to take up any excess nitrogen before it reaches the property boundary refer Appendix C Phosphorus tends to be adsorbed to clay particles and is therefore much less mobile and so the philosophy with this nutrient is to calculate the capacity of the soi
30. the reduced buffers 1 minimum buffer distance of one hundred 100 metres from the nearest edge of permanent watercourses including rivers creeks wetlands dams or lakes Design Guidelines for On Site Sewage Management for Single Households Page 9 Byron Shire Council Doc 491166 2 minimum buffer of forty 40 metres from the centre line of ephemeral water courses e g intermittent waterways drainage channels and dry gullies 3 minimum buffer of 250 metres to downstream or cross gradient domestic groundwater well and at least 50 m from upstream groundwater well 4 minimum buffer distances between the treatment and or land application area LAA other than ETA beds and a building or property boundary are as follows i for sites with slopes less than 10 5 7 degrees a three 3 meters when the building or boundary is up gradient of the LAA and b six 6 meters when the building or boundary is down gradient from the LAA and c 1 5 meters between adjoining subsurface application systems e g ETA beds and d six 6 meters from a swimming pool driveway building or property boundary 5 minimum buffer distances between the treatment and or land application area LAA for ETA beds should be double those listed above e g 6 m if building or property boundary is up gradient of the LAA and 12 m if it is down gradient from the LAA 6 effluent dispersal fields distribution networks i e pipes gravel etc should be l
31. volume of water used in the house 6 2 1 Septic Tanks The septic tank operates as a small anaerobic digester Septic tank effluent is much lower in settled solids than the raw influent but is still concentrated in nutrients and biochemical oxygen demand and generally requires some level of secondary treatment before it is suitable for land application refer Section 6 3 Additional information regarding the function sizing and management of septic tanks is provided in Appendix A Operation and maintenance advice is provided in Appendix G 6 2 2 Greywater Treatment Greywater or sullage is the term used for all household wastewater excluding toilet wastes for example the wastewater generated in a house with only composting toilets Greywater generally contains lower nutrients but can still contain significant levels of pathogens e g from showering and nappy washing NSW Health requires that greywater be disposed of below ground level unless it has been adequately disinfected Greywater must be collected in an in ground sullage tank sized in accordance with NSW Health requirements refer Appendix A where primary treatment can occur before being dispersed into the soil Where the site is unconstrained it can be piped directly from the sullage tanks into a suitably sized sub surface land application system refer Appendices B and C but it should be understood that this is likely to reduce the operational life of the land applicati
32. 166 Dispersive soil a soil that tends to disperse and erode especially in presence of high sodicity effluent Durable aggregate aggregate metal or stones which are graded to AS 2758 1 for single size coarse aggregate for nominal sizes usually ranging from 20mm to 50mm Effluent filter a device placed in the outlet of septic or greywater tanks to prevent or reduce solids entering the effluent dispersal area or next treatment step Effluent filters are not considered partial secondary treatment and do not provide secondary treatment defined below Effluent Liquid which has passed through a treatment system Evaporation the transfer of water from a liquid to a gas Evapotranspiration natural process transfers water from soil by evaporation and from plants by transpiration Evapotranspiration absorption ETA bed a specially prepared bed or area which promotes evaporation transpiration and absorption of effluent Faecal Coliforms a type of bacteria that live only in the gut of warm blooded animals Can be detected in the general environment if that environment is contaminated with mammalian excreta and therefore can act as an indicator of recent faecal contamination possibly by humans Geotextile a water permeable fabric used mainly to retain and stabilise soils Care must be taken to ensure that suitable geotextile spacing sizes and thickness are selected for the particular task Greywater the component of domestic sewag
33. 6 52 Phosphorus Removals ze euekn geen EEE E jena EENS ee 23 Design Guidelines for On Site Sewage Management for Single Households Page iii Byron Shire Council Doc 491166 6 5 3 Wet Weather Giorage 6 5 4 Holding Tanks PUMP Wells AA 6 5 5 Component Overtlows cece eeeaaeeeeeeeseeaeeeeaaesseaeeceaeeesaaeeseaaeseeeeeseaeeesaeeseeeeseas 656 Pittor Rain Tollel renerrien Eu ech thvep rte ieeevas thie atibeep RER aE de ETN 7 CHOOSING A LAND APPLICATION SYSTEM uu csccccseesssseeesseeeeseeeseneseseeeensneeeseaeseseaeenseeeeseeeesseeseseeneneeees ZE Absorption TRENCH CS eege ges AEEREERA Ae esos ERC ora naaa aaia E eaka 7 2 EvapoTranspiration Absorption ETA Beds ccccccccssseeeeneeeeeeeeeseeeeeeneneeeeeeeeeenneneees 7 3 Sub surface Drip Irrigation SDI cccccessseeeseeeeeeeeeeeeeeeeeeeneeeeeeeseeeeeeeeeeeeeeseeeeeeeeeeeneeeees T4 Spray irrigati niiin ee ee 7 5 Surface Dripper Under Mulch Irrigation cccseeccsseeeeeeeesseeeeeeeseneeeeeeeeeeeeeeeeeeeeeenseeeees 7 6 Special Components Used in Land Application Areas cccessecceesseeeeeeeeeeeeeneeeeeees POA ANGexing Valves scncscek tain i han charter tte F6 2 gt DOSING SIPHON EE 8 CALCULATING THE LAND APPLICATION AREA cccseesseesseesseesseesseesee seen eesaeseaeeeeeseseseenseenasenenans 9 DETAILS REQUIRED IN OSMS DESIGN REPORTS ccsseesseesseesseesseesseeseeeeeeeeeceseeaeeneeseseseensneneeenenae 10 INSTALLERS
34. 7 of AS1546 The NSW Health Department Register certifies manufacturers of the septic tanks and collection wells The sizing of pump wells shall be in accordance with the advice provided by NSW Health in their Septic Tank and Collection Well Accreditation Guideline refer Section 1 4 of Design Guidelines for download address Septic tank sizes are nominated for domestic flows of up to 14 000 L per week or daily flows of 2000 L The serviceable life of the tank is stated as 15 years The suggested minimum tank sizes unless NSW Health Guidelines mandate larger tank are set out in Table A1 If the correct size of tank is not available locally Byron Council requires that the next largest available tank be installed Table A1 Conventional Septic Tank Capacities Litres Type of Wastewater 1 3 Bedrooms 4 Bedrooms 5 Bedrooms 6 Bedrooms All wastewater 3 000 3 500 4 000 4 500 Greywater only 1 800 2 100 2 400 2 700 Blackwater only 1 500 1 800 2 100 2 500 Source AS1547 2000 Appendix 4 3A The location of the septic tank must be at a greater distance than 1 5m from any building and the base of the tank must not be within 45 angle of repose from the base of any footing or foundation Allowances must also be made for easy access to the tank in order for the pumping contractor to get a truck near the septic tank so that the contents of the tank can be periodically pumped out desludging the tank Septic tanks
35. A or s68 Approval No and date s approved Date installed Service provider and contract details G1 Details of Your Sewage Management System A domestic on site sewage management system is made up of various components which if properly designed installed and maintained allow the treatment and utilisation of wastewater from a house within the boundaries of the property Homeowners should acquaint themselves with what sewage management system is installed at your property and how it works If in doubt consult your service provider or Byron Council Your OSMS has been designed to cater for people and L day of effluent based on the understanding that the following water saving devices are installed If you are aware that more people are regularly using the system or if you wish to install extra water consuming devices e g additional bathroom or installation of a spa please consult Council to ensure that your system is capable of managing the wastewater loads The OSMS installed at your property comprise the following elements designers to add or delete information to make description relevant and accurate System Component Number Details e g manufacturer size relevant details Water saving devices Treatment System Composting toilet Septic sullage tank Outlet filter Aerated wastewater treatment system Sand filter Reed bed Appendix G to De
36. Byron Shire Council Design Guidelines for On site Sewage Management for Single Households Protecting the Environment and Health of Byron Shire 1 December 2004 Byron Shire Council Doc 491166 Foreword On site sewage management in Byron Shire Management of human wastes is an important issue affecting the water quality of Byron Shire especially in the more densely inhabited catchment areas Stricter environmental and public health requirements imposed by State and Federal government authorities as well as rising community expectations within the shire dictate the need to reassess and where necessary improve the on site management of household wastes In March 1998 changes were announced to the sewage management regulations A working group of government agencies including the NSW Department of Local Government the NSW Environment Protection Authority the NSW Department of Health the NSW Department of Land and Water Conservation and the NSW Department of Urban Affairs and Planning developed a set of guidelines EHP 1998 which requires that all major environmental and health issues are considered in on site sewage management in NSW Under these new regulations and guidelines councils and landowners must ensure that surface and ground water resources are protected degradation of land and vegetation systems is prevented public health risks are prevented natural resources are reused effluent irrigation compost and
37. Care should be taken to ensure that contact with sewage can be kept to an absolute minimum during routine maintenance and that no residents or neighbours will be exposed to pathogens during normal operation of the OSMS Appendix A to Design Guidelines Treatment Systems Page A12 Byron Shire Council OSMS Design Guidelines Appendix B 487903 Design Guidelines for On site Sewage Management for Single Households APPENDIX B Land Application Systems Appendix B Land Application Systems Page B1 Byron Shire Council OSMS Design Guidelines Appendix B 487903 Appendix B Land Application Options The E amp HP Guidelines 1998 and AS NZS1547 2000 describe the various systems that are available for land application areas in some detail The intention of this section is not to reproduce information that is readily available elsewhere but to expand and highlight points that are particularly relevant to the Byron Shire Byron Shire features large variability in micro climates and soil conditions and much of it overlies vulnerable groundwater resources DLWC Groundwater Vulnerability Map 1997 and different land application systems will be more appropriate in different localities Subsurface land application systems are preferred as they minimise the potential for human contact and rapid release to the environment Stewart et al 1983 Evapotranspiration mechanisms are considered the most environmentally means of managing t
38. Ecologically Sustainable Development is promoted and activities that are dependent on waterways are not adversely impacted e g swimming tourism and oyster growing eee e eo Councils also have specific responsibility under local government legislation to maintain a register of approvals granted for on site sewage management systems and prepare annual updates of State of the Environment reports for their areas showing details of polluted areas and on site sewage management policies performance of on site sewage management systems and the cumulative impacts of those systems on catchments within the council s area Every council is now required to prepare an on site sewage management strategy suitable for its local area Byron Shire Council s On Site Sewage Management Strategy was adopted in 2001 and is available from the Council Council has also produced a booklet for landowners giving a plain English overview of responsibilities and options The Home Owners Guide to On Site Sewage Management is also available from the Council for a small fee or without charge from Council s website www byron nsw gov au Front cover photo Sleepy Ck Bangalow photo by Cal MacKinnon Lush Photographics DISCLAIMER Byron Shire Council provides the information provided in this booklet in good faith as a guide only to Council and State Government requirements for on site sewage management for single households in Byron Shire All reasonab
39. G1 SOURCE TREATMENT DEVICES LAND APPLICATION AREA Secondary treatment Collection improves effluent Primary quality prior to land ee treatment application Evapo transpiration e g subsurface irrigation ETA beds Kitchen f f Bathroom Septic tank Sand filter Absorption Enge Greywater AWTS e g absorption y tank AWTS Reed bed Disposal irenches ETA beds Reuse Figure G1 Major Components of On Site Sewage Management Systems OSMSs Appendix G to Design Guidelines System Management Plan Page G3 Byron Shire Council OSMS Design Guidelines Appendix G 487883 G2 3 Source Reduction of Wastewaters and Nutrients G2 3 1 Recommendations for saving and managing water Reducing water usage will lessen the likelihood of problems such as overloading with your septic system Overloading may result in wastewater backing up into your house contamination of your yard with improperly treated effluent and effluent from your system contaminating groundwater or a nearby waterway On site systems generally work best when the wastewater load is minimised and shock loads e g sudden heavy loads such as when large numbers of people use the system for a short or uneven periods are avoided Spread heavy water use activities such as laundry over the week Replace single flush toilets with dual flush Install low flow shower roses Replace internal taps with low flow designs Purchase a front loading washing machine
40. Guidelines for On Site Sewage Management for Single Households Page 34 Byron Shire Council Doc 491166 On site sewage management system OSMS includes all types of human waste storage and treatment facilities e g septic tanks cesspits compost toilets urinals Also includes the wastewater application dispersal area e g absorption trenches irrigation fields OSMS Design Model a computer model based on a Microsoft Excel workbook which can be used to estimate appropriate sizings for land application areas and reed beds Pan Evaporation the loss of water by evaporation measured in a Class A pan The nearest weather station collecting Pan Evaporation data is at Alstonville Partial Secondary Treatment Post primary treatment not necessarily designed to achieve secondary treatment quality see below is more generally referred to in these Design Guidelines as partial secondary treatment In Byron Shire partial secondary treatment methods must be able to demonstrate that they can reduce contained nitrogen by at least 20 to be acceptable for blackwater inclusive systems Designers should also note that an ability to provide partial secondary treatment does not necessarily mean that these effluents will be suitable for all forms of irrigation without further filtration and an irrigation specialist should be consulted Pathogens micro organisms that may potentially cause disease or sickness These include but are not limited to bact
41. Households Page iv Byron Shire Council Doc 491166 1 INTRODUCTION In situations where it is not feasible to connect to a reticulated centralised sewage treatment system e g in unsewered rural areas wastewater generated from households must be managed on site In other cases even those who are connected to sewerage may wish to utilise at least some of their household wastewaters on site An on site sewage management system OSMS generally consists of three main components the wastewater source household treatment device s and final reuse or disposal of treated effluent via land application This document offers guidance for applicants owners and developers to plan the selection design installation operation and maintenance of on site sewage management systems OSMSs for single households in Byron Shire In particular it provides guidance for the appropriate selection and design of treatment system s and the application of effluent into the land The NSW Environment and Health Protection Guidelines E amp HP Guidelines 1998 referred to in the Foreword provide the statutory requirements and guidance for design of on site sewage management systems for single households in NSW Australian Standard AS NZ1547 2000 also provides important additional technical information on the subject These Design Guidelines for On Site Sewage Management for Single Households 2004 hereon referred to as the Design Guidelines provide local interpret
42. ICATION AREA Secondary Collection treatment Primary improves effluent Evapo transpiration treatment quality prior to land R e g subsurface t application euse irrigation ETA beds Flush toilet Wes TH Penal Septic tank Sand filter Absorption G E Greywater AWTS e g absorption unary tank AWTS Reed bed Disposal trenches ETA beds Figure 1 Major Components of On Site Sewage Management Systems OSMSs The process of designing an OSMS involves gathering interpreting and reporting information relevant to each part of the treatment train Thus designing a suitable OSMS requires a good understanding of the soils and other physical variables of the site e g slope aspect and shape of the land the wastewater generating activities of the household and an extensive knowledge of the available treatment and land application options 2 1 RECOMMENDED DESIGN STEPS A number of steps are involved in successfully designing an OSMS in Byron Shire as summarised in Table 1 Generally once preliminary information has been gathered via desktop search a detailed site and soil assessment is carried out to identify any potential constraints and limitations of the site for managing effluent Once the site limitations are known suitable treatment and land application options can be identified that will address any constraints appropriately Table 1 should be used as a checklist when preparing an OSMS design report for submission to Council Reference
43. Install a waterless composting toilet Do not install spa baths unless this has been specifically accounted for in the OSMS design If a spa bath has been installed use sparingly and release the water slowly See ee e e Additional information to be added by system designer as appropriate G2 4 What can my OSMS cope with G2 4 1 Detergents The use of detergents low in phosphorus and sodium is recommended for use in households with on site systems Detergents high in sodium can lead to soil degradation in the land application area leading to a reduction in permeability a consequent risk of surcharging sewage and the need for early replacement of the application area Note Concentrated and liquid detergents often contain much less phosphorus and sodium than equivalent powder detergent products Potassium based liquid soaps eg Castile soap are also recommended G2 4 2 Food and Cooking Oils It is anticipated that some food and cooking oils will be washed into wastewater treatment devices and all systems discussed in Appendix A of the Design Guidelines are capable of handling a limited amount of these However most systems other than very large septic tanks are likely to become overloaded if large volumes of food and or cooking oils enter them For this reason the following broad guidelines should be followed to protect your OSMS Food and cooking oils should be kept to a reasonable minimum by keeping food strainers in kitchen
44. Model Worksheet Despite its more visually complex layout the Design Model can be run in the same uncomplicated mode as the Designer Input Sheet The easy to use 14 step process described above for the Designer Input Sheet is with the exception of the sequential order of steps 1 4 replicated on the Design Model worksheet The main difference between the two models is the increased level of interactivity in the Design Model resulting from options to overwrite some of the model default values and the option to consider varying sizes of reed bed treatment available in the Design Model worksheet As with the Designer Input Sheet some preparation and data gathering is required prior to running the Design Model Several extra output parameters are included in the Design Model and these include The minimum land application area and the ability to compare the areas required for phosphorus and nitrogen dispersal Nitrogen Report ETA trench configuration C1 6 Design Model Example The following example applies the model to a second situation which might typically be encountered in Byron Shire A family of four are to build a three bedroom home plus a self contained single bedroom studio to be leased under permanent occupation The two hectare 20 000m south easterly facing property lies in a fertile valley several kilometres south west of Mullumbimby The property has a water bore which yields drinking quality water supplementary water
45. REQUIREMENTS csccessceseseesseesseneeseeeseeeseeesneessneeseeessnessaescaeeeaeeeaeseeeseeeaeenadanensenasanenanes 11 GLOSSARY AND ACRONYMS 0 o ccccscesceseeeeeeseeesenessnessneeseesseeesueeseesnessaeecaeecaeeeaeseeesaeeaaenasanessensaenenanes 12 FREFERENGES eege reese SEENEN du LIST OF TABLES Table 1 Steps required in preparation of an OSMS design report for Page 5 submission to Byron Shire Council Table 2 Soil Landscapes in Byron Shire showing likely limitations Page 10 for effluent dispersal and phosphorous sorption Table 3 Soil Texture Grades Page 11 Table 4 Soil structure according to degree of pedality Page 12 Table 5 Abundance a and Size b of Coarse fragments Page 13 Table 6 Limiting Site Conditions for Land Application Areas and Page 14 Suggested Solutions Table 7 Soil limitations and suggested solutions Page 15 Table 8 Strengths and weaknesses of secondary treatment options Page 18 LIST OF APPENDICES APPENDIX A Treatment Systems 487879 APPENDIX B Land Application Systems 487903 APPENDIX C User Manual for the OSMS Design Model 487794 APPENDIX D Native plants suitable for Land Application Areas 487906 APPENDIX E OSMS Treatment System Checklist 422469 APPENDIX F OSMS Land Application System Checklist 459030 APPENDIX G OSMS Management Plan Pro Forma 487883 See also Byron Shire Council OSMS Design Model 487846 Design Guidelines for On Site Sewage Management for Single
46. Sandy Waterlogging high watertables low CEC 1 000 Podzolic Wollongbar wo Red Basaltic High permeability 10 000 5 2 1 Soil Texture Classification Soil texture may be measured by the behavior of a small amount of soil incrementally moistened and kneaded into a small ball bolus then manipulated between the thumb and forefinger to form aribbon The soil is then categorised from the behavior of the moistened bolus and the length the squeezed ribbon achieves before shearing or failing There are six broad texture categories which are used to classify the likely permeability of soil as set out in Table 3 Each texture group and any change in texture group within the soil profile Design Guidelines for On Site Sewage Management for Single Households Page 12 Byron Shire Council Doc 491166 should be recorded The following table is provided to assist in determining the soil texture category Table 3 Soil Texture Grades Source Northcote 1979 and AS NZS1547 2000 Soil Category Texture Group Grade of Soil Texture Behavior of moist bolus Indicative ribbon length before failure mm nil to very slight coherence won t mould Sand single grains adhere to fingers Ee 1 Gravels amp Loamy sand slight coherence lt 6 35 sands slight coherence sticky when wet many Clayey sand sand grains stick to fingers discolours 6 35 13 fingers wit
47. Soil limitations and suggested solutions SES S Suggested solutions Soil Feature Examples of limiting conditions to limitations Soils in proposed land application area found to be dispersive i e Class 3 or 4 in Table 4 1 1 of AS1547 2000 sodic or prone to shrink swell characteristics Coarse Fragments Coarse Rock fragments occupy gt 20 of soil fragments rocks boulders volume impede absorption Field pH Dispersive or swelling Soils using modified Emerson Aggregate test Add gypsum or otherwise amend soil Improve or increase second stage treatment and or increase application areas Increase size of land application area proportionally Improve or increase second stage treatment Conditioning with lime may assist if pH lt 5 5 pH lt 5 5 or gt 8 pH extremes inhibit plant growth Design Guidelines for On Site Sewage Management for Single Households Page 17 Byron Shire Council Doc 491166 6 CHOOSING A TREATMENT SYSTEM This section provides information to assist in selecting the most suitable treatment system that will satisfy the needs of the given homeowner and adequately deal with any site constraints such as close proximity to waterway or small block size For each treatment system general information is given regarding its function and form and important information relevant to the operation and maintenance of each system is provided More detailed information for use in the design and siz
48. aerobic conditions Septic tank treatment process comprise sedimentation of settleable solids flotation of oils and fats and anaerobic digestion of sludge Sewage Untreated or partially treated human wastes generated from toilets baths sinks lavatories laundries and other plumbing fixtures in places of human habitation employment or recreation Design Guidelines for On Site Sewage Management for Single Households Page 35 Byron Shire Council Doc 491166 Sewage management facility a human waste storage facility or a waste treatment device intended to process sewage including a drain connected to such a facility or device Sewerage The network of collection drains carrying domestic wastewater or effluent away from properties for off site treatment Sewerage work for the purposes of Council approvals sewerage works include the construction alteration extension disconnection removal ventilation flushing or cleansing of any sewerage service pipes or fittings or fixtures communicating or intended to communicate directly or indirectly with Council s sewerage system Single Households these Design Guidelines apply to single households which is defined here as the domestic residence of a single family or small group of people lt 10 persons Sludge mainly organic semi solid product produced by wastewater treatment processes Sub surface Irrigation pressurised effluent dispersal system Irrigation lines are buried 100m
49. age evapotranspiration gt Shrubs are recommended to be planted no closer than one 1 metre from the sidewall of the ETA bed or trench and small trees no closer than five 5 metres Large trees such as eucalypts figs or mangoes should be planted a minimum of 20 metres from the beds to avoid root damage in the distribution system and reduce shading of the ETA beds gt On sloping sites of up to 10 ETA beds shall be terraced along the slope and reinforced as required to ensure that they will be stable in the long term Qualified geotechnical advice should be sought if beds are to be installed on slopes of greater than 10 or on unstable soils gt Adequate run on diversion mounds or trenches must be provided to prevent run on onto the beds On highly sloping or constrained sites Byron Council further recommends that a swale be constructed downstream of the beds and planted with vetiver grass or other high nutrient loving plants to assimilate any occasional surcharges from the beds Maintenance requirements for ETA beds including annual maintenance checks are provided in Appendix G B4 Irrigation Dispersal Systems The most dependable and most popular means of dispersing effluent in a way that maximises uptake by plants within the land application area is by means of pumped irrigation Appropriate design of pumped irrigation systems for domestic wastewaters requires a good understanding of pumps pipes and emitters For this reason s
50. aids the uptake of water vapour through transpiration and evaporation processes It is worth noting that meteorological stations are invariably located in positions fully exposed to sun and wind The daily water balance model recommended in these Design Guidelines Appendix C and OSMS Design Model which are based on Alstonville climate records would not be representative of a damp shaded area Any such areas should be marked on the site plan and avoided in the selection of the land application area Refer to AS NZS1547 2000 for further advice 5 1 5 Boulders Floaters Rock Outcrops Boulders floaters or rock outcrops may reduce the effectiveness of effluent polishing mechanisms in the soil Rocks make installation more difficult and may also restrict infiltration and allow sewage to short circuit the dispersal field and more rapidly enter waterways Refer also AS NZS1547 2000 Proposed application areas should be traversed on foot and the presence of any boulders floaters or rock outcrops should be recorded in the site plan Note The definition of a boulder is a rock whose middle dimension is at least 600mm see Glossary Shallow bedrock is a significant constraint because it greatly limits the natural assimilation capacities which might otherwise be provided by clay soils and may provide a much faster and much more poorly filtered conduit to groundwater resources Where investigations indicate that the C horizon weathered bedrock lie
51. al agricultural or industrial applications etc Until this document is prepared these applications will need to be designed by specialists in the field in consultation with Council officers Finally Byron Shire Council also offers a plain English version of on site sewage management options called The Home owners guide to on site sewage management This is a greatly simplified version of the Design Guidelines and if any ambiguities arise between the two documents the advice in these Design Guidelines shall prevail 1 2 GUIDING PRINCIPLES Byron Shire Council s On site Sewage Management Strategy aims to protect our local waterways and their capacity to assimilate and transform wastes without altering the quality of their ecosystems The Strategy also advocates the reuse of nutrients and hydraulic loads from sewage preferably to achieve some beneficial outcome such as the diversion of high quality potable water resources from garden watering duties In order to achieve the aims of the Strategy these Design Guidelines provide guidance and information to ensure sites are adequately assessed and on site sewage systems are designed and installed in a manner that does not threaten public health or the downstream environment The Design Guidelines adopt the precautionary principle in attempting to ensure that the long term environmental impacts of OSMSs are minimised through the implementation of current best practice sewage management approaches
52. and may be used to deliver effluent to sand filters and or ETA beds They are recommended in sloping sites where a fall of over at least two meters exists between system elements refer to product literature for more detailed advice Design Guidelines for On Site Sewage Management for Single Households Page 26 Byron Shire Council Doc 491166 8 CALCULATING THE LAND APPLICATION AREA Once the site and soil assessment has been completed and an assessment made on what effluent treatment and dispersal options are available the next step is to calculate the size of land application area that would be required for each option This is often an iterative process as greater treatment will enable the installation of a smaller application field and vice versa Consultation with your plumber or other professionals may also assist in determining the most sustainable and cost effective solution for your situation In accordance with recommendations in EPHG 1998 reserve application fields are required for new systems A computer model is available from Byron Shire Council to calculate the area required for the land application area and to test the relative benefits of the various treatment systems referred to herein as the Byron OSMS Design Model or more simply as the Design Model Designers are welcome to submit designs based on any other model or rationale provided that the calculations and parameters are sufficiently justified and are consistent with
53. and media in recirculating sand filters need to be coarser than that used in single pass varieties due to the higher loading rates Unless the sand filter has been designed to ensure that an anaerobic zone will be present treatment in single pass sand filters is likely to be almost exclusively by aerobic treatment Aerobic only sand filters typically produce very good TSS and BOD removal but may achieve little or no removal of total nitrogen If an anaerobic zone or many anaerobic micro sites can be sustained within the sand filter however some denitrification can also be reliably achieved Denitrification rates in sand filters tend to be limited by having insufficient carbon available in the effluent for the conversion from nitrate to nitrous gas One solution to this design issue is to direct a proportion of 1 4 to 1 3 of the nitrified sand filter effluent via an indexing valve for example back Appendix A to Design Guidelines Treatment Systems Page A5 Byron Shire Council OSMS Design Guidelines Appendix A 487879 to the primary treatment tank taking care not to disrupt the crust in the tank The plentiful organic carbon and anaerobic conditions available in the tank will promote the removal of nitrogen in a gaseous form through the process of denitrification Based on literature reviews Byron Shire Council expects that a reduction of around 30 nitrogen can be achieved either by a suitably sized and intermittently dosed single pa
54. and preferably quarterly by a qualified professional as part of the maintenance requirements Suitably located pressure release valves and flush pits must be provided to allow this regular flushing maintenance without causing pollution There are a number of different types of proprietary SDI systems on the market Council requires that all new installations use pressure compensated emitters and strongly prefers the use of non drain varieties Non drain emitters have the dual advantage of not draining out after the pump cycle has finished and are also much less prone to root invasion The following design features shall be integrated into SDI designs unless sufficient justification is provided for alternative designs gt Design and installation must comply with the requirements of AS NZS1547 2000 gt The maximum size for a single sub surface irrigation field is 500 m If a bigger application area than this is required to reliably disperse the household effluent it should be broken up into smaller fields and the effluent load should be alternated through the fields via an indexing valve refer Section 4 6 gt Pumps must be sized to match the hydraulic characteristics and requirement of the irrigation system including friction losses through pipes and filters gt Flushing velocity in all flush lines shall be between 0 8 m s and 2 m s gt Gravel filled flushing pits should be adequately sized to accept design flush loads and
55. appropriately experienced service providers and most other systems require an annual service by a similar provider refer to Council s Conditions of Approval for detailed requirements It will be a requirement of all Approvals to Operate that a form similar to those provided in Appendices E for Treatment System Service Form and or F Irrigation System Service Form is to be submitted to Council within 7 days of servicing the system or component Inspections Land application areas are to be planted out in accordance with the approval and or effluent report prior to occupation of the dwelling suitable plants for effluent application fields are provided as Appendix D Permission to occupy will be generally refused should the nominated land application area and planting schedule not be completed Inspections of external drainage lines and the whole effluent dispersal system can only be carried out by Council Officers Private certifiers or designers do not have authority to inspect any aspect of on site sewage installations or drainage It is a requirement that the installer contacts Council prior to back filling any sub surface installation so that the system can be inspected and tested It is necessary to provide a minimum of 48 hours notice for a Council inspection Consultant s reports and Council Approvals indicating that land application areas on a specific site are to include the application of lime loam gypsum sand dosing or
56. asia brisbaniensis 1m Cunjevoi Lily Alpinia caerulea 1 5m Native Ginger Appendix D to Design Guidelines Plants suitable for land application areas Page D2 Byron Shire Council OSMS Design Guidelines Appendix D Recommended Plants 487906 Callistemon pachyphyllus 1m Wallum Bottlebrush Cordyline rubra C petiolaris 3m Palm Lilies Crinum pedunculatum 1m River Lily Enydra fluctuans 50cm Helmholtzia glabbristylis 1m Stream Lily Melastoma affine 50cm Blue Tongue Persicaria spp 50cm Knotweeds Philydrum lanuginosum 1m Frogsmouth Pipturua argenteus 50cm White Nettle Tetragonia tetragoniodes 50cm Warrigal Greens Ferns Blechnum indicum 1m Bungwall Blechnum cartilagineum 1m Gristle Fern Christella dentata 1m Binung Cyathea australis 3 5m Tree Fern Cyclorus interruptus 80cm Shrubs Small trees Banksia ericifolia 3 5m Heath Banksia Banksia robur 1 3m Swamp Banksia Callistemon salignus 5m White Bottlebrush Callistemon viminalis 5m Weeping Bottlebrush Evodiella Muelleri 3m Little Evodia Ficus coronata 5m Creek Sandpaper Fig Hibiscus diversifolius 1 5m Swamp Hibscus Leptospermum flavescens 3m Common Ti Tree Leptospermum liversidgeli 1m Lemon Ti Tree Melaleuca nodosa 3m Paperbark Melaleuca stypheloides 5m Prickly leaved Paperbark Myoporum acuminatum 3 5m Mangrove Boobialla Omalanthus n
57. ation The model calculates an annual total phosphorus budget based on TP input soil adsorption potential and crop uptake Default values for TP input and crop phosphorus uptake is 0 6kg person yr and 20 kg ha yr respectively The adsorptive capacity of the soil is considered to be finite and is based on predicted soil adsorption capacity for soil type default values for known soil types are listed in the model data base The soil adsorptive capacity is reduced by both depth to rock or water table minus a default 0 5m water table buffer The design life of the land application area is restricted to 50yrs in the case of the phosphorus calculation The model considers the treatment disposal process in a series of compartments or sub models which can be described as Appendix C User Manual for OSMS Design Model Page C4 Byron Shire Council Doc 487794 P loss in Source disposal re use area P loss during Household Treatment Soil Adsorption phosphorus Crop Uptake output Loss To Drainage accepted as zero unless sandy soil Figure C2 Phosphorus balance sub model within OSMS Design Model The equation for the phosphorus application area is Area m 10 000 x Pioaa Pessrg VW B 7 Tet Peetop eincancecsccastosazascnsketess sseceniaetaanoedenatasteters Eqn 1 Where Area land application area required for soil plant P removal 10 000 conversion factor from hectares to m Pioad dwelling P output less a
58. ation of the treated effluent The information gained from the site and soil assessment will ultimately be used to determine the type size and location of the land application system and the level of treatment required to overcome any constraints Different situations require different levels of assessment especially where there are limitations to be surmounted It is stressed that site and soils assessment are specialised disciplines and it is not possible to include in these Design Guidelines all the relevant and necessary information that professional assessors are required to understand refer Section 1 3 for further information The following sections explain in detail the various parameters required for a site and soil assessment If constraints are found during the site and soil investigations designers should examine options for ameliorating these constraints refer Table 6 5 1 SITE EVALUATION PROCEDURES Most of the following information is drawn from the Australian Standard AS NZS1547 2000 The information below will help you evaluate your site s capacity to manage on site sewage Table 9 5 1 1 Slope Angle Refer also AS NZS1547 2000 The slope of the site especially the proposed application area s should be determined in the field through the use of such instruments as an inclinometer over at least 20 m distance or through a formal survey of the site Slopes greater than 15 8 5 degrees are regarded as severely li
59. ations of these state and federal guidelines for Byron Shire but do not replace or diminish their importance System designers must be familiar with all of the above guidelines if they intend to submit an OSMS design to Byron Shire Council 1 1 SCOPE AND APPLICABILITY These Design Guidelines are intended to provide guidance for those designing and installing on site sewage management facilities for single domestic dwellings in Byron Shire They provide information on preparing an on site sewage management report the design of OSMSs in sewered and unsewered areas Byron Shire Council s on site sewage management objectives and guiding principles and aglossary of technical terms used in the industry These Design Guidelines do not specifically apply to systems servicing more than a single household or dwelling Package treatment plants and systems designed to cater for more than one household will be covered by separate guidelines and until these are available will be dealt with on a case by case basis Further these Design Guidelines do not provide specific information on designs for subdivision of land off site sewage management systems specific advice for OSMS in urban areas multiple dwelling combined or package sewage management systems agricultural commercial and industrial developments or patented sewage treatment systems ee e e e Nevertheless these Design Guidelines may provide useful information w
60. be split along strict greywater black water lines A combined system is less costly due to the need to purchase only one tank and install one disposal field particularly if an AWTS is used As the minimum size for a septic tank is 3000L the separation of treatment is less economic On the other hand a separate system provides a slightly longer retention time hence better treatment as two separate tanks have a greater combined capacity than one A8 Disinfection There are a number of options for effective long term disinfection for on site systems the most common being chlorination and UV radiation Disinfection through a UV lamp can be fairly cheaply achieved and is preferred by Council as there is no need to use harsh chemicals Chlorination disinfection is used with many AWTS installations Any form of disinfection generally requires a well clarified effluent low in organic matter and suspended solids i e secondary treated in order to be effective Subsurface irrigation does NOT require disinfection of effluent unless it is a specific requirement of the manufacturer or NSW Health but does require at least partial secondary treatment For surface spray or dripper under mulch irrigation systems the effluent must be disinfected as well as partial secondary treated refer Section 6 3 of Design Guidelines In designing any OSMS it is important that the risks to householders and system maintainers from pathogens in sewage and solid wastes
61. characteristics to the primary field shall be designated and set aside in all new applications The reserve field may be required if the primary application field fails over time due to for example reductions in permeability caused by interactions with sodic effluent or the soil s capacity to absorb phosphorus becomes super saturated 7 1 ABSORPTION TRENCHES The traditional absorption trench is the archetypal disposal only system Because there is little opportunity for reuse or treatment through plant uptake and because it is difficult to distribute effluent evenly in a way that does not pollute in the long term traditional trenches are discouraged in new OSMS installations Systems which rely on soil absorption as the principal mechanism e g absorption trenches generally do not comply with the requirements of these Design Guidelines or the NSW EHP Guidelines 1998 p119 On some highly constrained lots where insufficient space is available for any other form of land application absorption trenches may be the only viable option for effluent dispersal In these cases Byron Shire Council would generally expect that absorption trenches be preceded by at least secondary treatment and that all necessary efforts would be made to disperse effluent evenly over the entire length of the trenches e g by pumping or intermittently dosing On highly permeable soils which are located a sufficient distance above the standing water table benea
62. considered an acceptable or sustainable form of long term land application system in Byron Shire Because absorption trenches offer almost no opportunity for vegetation to pump out and reuse nutrient rich effluents comprehensive justification and secondary effluent treatment prior to dispersal would need to be provided should an absorption system be proposed Even with secondary treatment Council generally views absorption trenches as only a short term solution to an existing problem If trench designs are to be submitted they should as a minimum be designed in accordance with AS1547 2000 On highly permeable soils which are located a sufficient distance above the standing water table beneath it may sometimes be acceptable to use a discharge control trench in which the trench beneath the distribution pipe is deepened and filled with washed sand A standardised design for this type of trench is provided in AS1547 2000 B2 Mound Systems Mounded systems are effluent dispersal devices constructed above the land surface from imported fill material usually sand capped with soil These raised beds are used in situations where drainage of the natural soil is a problem or where the underlying groundwater seasonally reaches a height of less than 1 2 m below ground level or areas where flooding occurs periodically Water dispersal is by evapotranspiration and some soil absorption Denitrification can be achieved within mounded land applicatio
63. ctor contractor to contractor to contractor to required service service service Construction cost High High High Moderate Nitrification Good Good Good Poor to moderate Nitrogen removal Low Low Good Moderate to good Intermittent dosing No Yes Yes No needed Tolerance to peak Low Low Moderate Very good loads Tolerance to low loads Low OK OK OK holidays Visual impact Low unless Can be hidden Can be hidden Moderate can above ground be landscaped Awareness Does the No No No Yes device invite user participation amp hence awareness commitment 6 3 1 Aerated Wastewater Treatment Systems AWTS Aerated wastewater treatment systems AWTS have become popular in recent years and a range of proprietary systems is available on the market AWTS s are small scale package treatment plants that are conceptually similar to large scale sewage treatment facilities They typically produce an effluent which with sufficient filtering can be distributed straight into a subsurface dispersal system i e partial secondary effluent quality with 20 nitrogen reduction AWTS s depend on steady state microbiological conditions reliable electrical supply and regular maintenance of mechanical and electronic components to sustain reliable treatment Failure or a sustained interruption in any part of the system e g as a result of power interruptions or when a tourist dwelling is unoccupied during the off season can lead to a defini
64. d level Council or the NSW Department of Public Works may be able to supply flood height records in some areas 5 1 9 Site Drainage The frequency and duration of seasonal shallow waterlogging should be noted Signs of poor drainage include hard packed soils vegetation growth characteristic of damp sites and pooling of water It is not recommended that land application areas be installed within sites with poor drainage The location of channeled concentrated runoff on site as well as any runoff likely to move onto neighboring properties should be noted on the site plan refer also AS NZS1547 2000 and avoided in the siting of the Land Application Area 5 1 10 Vegetation Indicating Waterlogging While wetland species such as bulrushes etc are obvious signs of frequent waterlogging other less obvious species such as sedges and buffalo grass can in this region indicate seasonal Design Guidelines for On Site Sewage Management for Single Households Page 10 Byron Shire Council Doc 491166 waterlogging The presence of these or other moisture loving species should be noted in the site plan 5 1 11 Surface Condition Note cracks hardness previous compaction patterns dampness and the location of seepage areas refer also AS NZS1547 2000 5 1 12 Fill The location depth and type of any fill should be noted on the site plan as shown in AS NZS1547 2000 Clean fill consisting of soil which has settled and is on a stable site
65. del designers are expected to use their skills and knowledge to reject or modify designs that will not work over the required minimum fifteen year design lifetime of the system C4 Using The Model Case Study Examples Once the workbook file has been downloaded from the web the model is ready to use within a Microsoft Excel environment The model opens to the default Data Input worksheet identified by the green worksheet tab at the bottom left of the page Users will see two further worksheets listed by colour tabs in the lower left corner of the screen the Council Report Page red tab and the Designer Model blue tab It is anticipated that most designers will find it easiest to use only the Data Input and Council Report pages One peculiarity of the Excel spreadsheet should be highlighted up front each input value must be entered by entering the value and hitting the Enter button on the keyboard otherwise the Calculate function and list boxes will remain inoperable Should a dialogue box appear offering to debug the model users are advised to hit No or Cancel and proceeding on C5 Examples Using the Data Input Worksheet of Design Model The Designer Input Sheet is an easy to use 14 step process that will compute the minimum land application area required for your on site wastewater system Before running the model some preparation and data gathering is required You will need to find out what type of soil exi
66. dix G to Design Guidelines System Management Plan Page G7 Byron Shire Council OSMS Design Guidelines Appendix G 487883 e Ensure that urine is able to drain from the compost it will quickly turn septic if the compost is kept too wet Manually clean the pedestal regularly Do not use bleach cleansers or dispose of poisonous cleaning agents into the toilet Remove compost when it builds up or appears full Bury compost for three months before use Use compost only on trees etc and not on vegetable gardens Use gloves or wash hands thoroughly after each handling do not allow small children to have access G3 1 7 Pump Wells Pump wells are in ground sealed chambers which enable collection of effluent for intermittent pumping to the land application system or next treatment process If installed pump wells must be checked by the service provider as part of the annual maintenance check This annual maintenance should include servicing of pumps and electrical components and a check that the float switches are correctly set and operating The home owner is also encouraged to regularly check that the high level alarm switch is operating and that there are no significant sludge build ups or other problems Additional information should be added by system designer as appropriate to the above sections G3 2 Land Application Dispersal Systems Common to all land application systems are the following maintenance principles to pro
67. dstone nutrient poor soils If in doubt ask your nurseryman or a horticulturalist Macrophytes suitable for use in reed beds are listed in Appendix A4 5 Scientific name Height Common name Sedges Rushes Reeds Baumea articulata 1m Jointed Twigrush Baumea rubiginosa 1m Rush Bolboschoenus fluviatilis 2m Club Rush Carex appressa 1m Sedges Carex fasicularis 1m Tassel Sedge Carex gaudichaudiana 1m Sedge Cyperus exaltatus 1m Sedge Eleocharis equisetina 1m Spike Rush Fimbristylus spp 50cm Gahnia clarkei G sieberiana 1 5m Sawsedge Juncus polyanthemos J usitatus 1m Reed Juncus krausii 1m Salt Rush Lepironia articulata 2m Grey Sedge Lomandra hystrix 1m Creek Mat Rush Lomandra longifolia 1m Long Leaf Mat Rush Scirpus mucronatus 50cm Triangular Club Rush Schoenoplectrus validus 1m Typha orientalis 1 5m Bulrush Grasses Ground covers climbers Bacopa monniera Centella asiatica 20cm Pennywort Oplismenus ameulus 30cm Grass Oplismenus imbecillis 30cm Grass Paspalum distichum 50cm Water Couch Pollia crispata 80cm Pollia Pseuderanthemum variable 50cm Pastel Flower Themeda triandra 80cm Kangaroo Grass Vetiveria filipes 1m Native Vetiva Viola betonicifolia 30cm Arrow leaved Violet Viola hederaceae 30cm Native Violet Penniselum clandestinum exotic 30cm Kikuyu Setaria spacelata exotic 30cm Setaria species Forbs Small plants Aloc
68. e information about approvals contact Byron Shire Council G4 1 ATO application fees Application fees for approvals to operate are spent on the cost of processing applications development and implementation of Council s on site sewage management strategy provision of advice and assistance to owners of existing systems and enforcement of legislative provisions Appendix G to Design Guidelines System Management Plan Page G10 Byron Shire Council OSMS Design Guidelines Appendix G 487883 _ 1 How to check the sludge and scum depth of your tank 1 Take a metal or plastic stick eg electrical conduit about 4m long Wrap it tightly from end to end with towellina or cloth 2 Wearing rubber gloves remove the inspection cover inlet end and insert dip stick all the way to the bottom of the tank Health amp Fire Hazard Always wear gloves don t smoke and keep naked flames away 3 Withdraw it completely observe the size and position of the scum mark 4 Compare the marks on the dip stick with the diagnostic illustrations on the next page bottom and the sludge mark top Health caution Put the cioth strip in a waste bag and burn or place in the garbage Wash down the stick and place in sunlight out of reach for a few days Dispose of the gloves or soak them in a mild bleach solution and wash your hands and arms thoroughly Appendix G to Design Guideli
69. e 5 4 ESTIMATING WASTEWATER GENERATION scceseeeseseeesneeenseeeeeseeescaeseneeeeneeeessaesasaaesaseeeeeeeeeseaeseseneeeees 6 4 1 Predicted Hydraulic Elo ei re regg esgecngseggdbaggdh ebeeeugd Sege edd geet 6 4 2 Nutrients and Fategieng2 ussere ees eebe EENS EENEG 6 SC RM Tree 6 4 2 2 Pathogens IN SCwWaGe EE E 6 5 SITE AND SOIL ASSESSMENT wcsccocisdeccesccaccclieevece sagececcncde stacey ccndesscseeccaueducecvateescaaeyctudesdhecesnacessucteassstescueseecu 8 5 1 Site Evaluation Procedures ccccssseccccesseeeeeeeeeeeeeeeseeeeeeeseseeeeeeeeseeeeeseesseeeeeeseeneeeeneesenees 8 5 1 1 Slope Angle Refer also AS NZS1547 20001 8 E ele 8 eS GAS POC eege se dear sa den cues ee E duce a talaga tenets ae ayes talaga me ae ud 9 ep Me 9 5 1 5 Boulders Floaters ROCK Outcrops sssseesesssesssesrietesttiestnntnnnttnntnutnnntnnntnnssnnnnnnntnnsnnnnenn nnt 9 5 1 6 Butter DIstanCes moesie urania iiai d iiie aiaia a ia a adao adiada ee deeg 9 5 1 7 Run on and Upslope Geepnage nnt 10 51 8 Flooding Potential ENEE ieni oeei apee a diag de adia aata e i Gd 10 51 9 Site Drainag E Eegeregie edd aai a iaki deed eae dea Bae 10 5 1 10 Vegetation Indicating Waterlogging ceeeseeeeeeeeeeeeeeneeeeeeaeeeseeaaaeeeeeeaaeeeeeeaaeeeseenaeeeeeeaaes 10 SATI Surface Oploe ereecht deet Gen ae 11 CHE BE eege E eegeedegt d neie EEN Eeer eege 11 5 1 13 Erosion Mass Movement 11 UE WAU AE LOIN EE 11 5 2 1 Soil
70. e been used in reed beds throughout the world with species from the genera Phragmites Schoenoplectus and Typha being the most commonly used Macrophytes that have been successfully used in this region are Schoenoplectus validus river club rush Typha orientalis bull rush Phragmites australis common reed Bolboschoenus fluviatilis marsh clubrush Lepironia articulata grey rush Baumea articulata jointed twigrush Lomandra hystrix not longifolia Carex bichenoviana and For the reasons discussed above Phragmites australis should never be planted if flexible plastic or stainless steel liners are to be used Tube stock for most wetland plant species may be purchased from nurseries that specialise in wetland plants These plants can also be propagated vegetatively by dividing root clumps obtained from existing constructed wetlands An initial planting density of at least 3 plants m is required for new installations A4 6 Inlet structure The inlet structure for small reed beds usually trench arch or a slotted 100 mm diameter PVC spreader pipe should extend almost the full width of the reed bed and should be placed below the gravel surface with large stones placed around it Appendix A to Design Guidelines Treatment Systems Page A9 Byron Shire Council OSMS Design Guidelines Appendix A 487879 Inlet areas of wetlands are prone to accumulation of sludge so it is important that the inlet is accessible and monitorable for
71. e household water source will be e g tank water or reticulated supply and whether water saving devices are installed Note that Council will need to confirm that any water saving devices claimed in the design are installed when it inspects the OSMS refer Section 10 The daily volume of household effluent that the OSMS will need to cater for is then estimated by multiplying the number of persons expected to reside there see above with the expected effluent generation rate from AS1547 2000 These calculations are performed within a subroutine of the Byron OSMS Design Model refer Appendix C 4 2 NUTRIENTS AND PATHOGENS Besides the volume of water there are two other components of domestic sewage which need to be closely considered by the OSMS designer nutrients e g carbon nitrogen and phosphorus and pathogens 4 2 1 Nutrients in Sewage The often high levels of nutrients found in sewage can be either a potential source of pollution if they are allowed to reach surface or groundwaters or a resource in sustaining the growth of lawns and gardens As indicated in the Guiding Principles Section 2 1 the challenge for the OSMS designer is to reduce the nutrient levels and spread those that remain in the effluent in such a way that they will virtually all be taken up by plants in the land application area and virtually no excess nutrients will reach the groundwaters or neighbouring surface waters It is expected that compliance with these
72. e to the line B block size Equations 2 amp 3 are re arranged within the nitrogen sub model to calculate land application thus Area m 1 Nim Nireat Naenit X Nireat Naenit Norop X EE Eqn 4 Nitrogen Calculation amp Creek Buffers Reductions from the recommended minimum buffer distances to waterways restricts the nitrogen calculation by reducing the allowable nitrogen release to the environment The nitrogen sub model does this as a simple linear reduction i e if the buffer distance between the proposed land application area is 50m where the guidelines require 100m then the effective block size is reduced by 50 Essentially the model increases land application areas by reapportioning the entered block size value C1 5 Conclusion Land application areas must be able to accommodate all three processes in order to protect surface and ground water human health and ecosystems Designers should understand that neither guidelines nor computer models can replace professional knowledge and experience In some cases the current draft OSMS model may suggest impractical options that may not be technically feasible e g sub surface irrigation may be of a computed size but irrigation will only work if the effluent is sufficiently filtered to not clog the emitters or environmentally desirable As Appendix C User Manual for OSMS Design Model Page C6 Byron Shire Council Doc 487794 well as using the guidelines and mo
73. e which excludes toilet and urinal wastes Groundwater the body of water held in the soil and rock pores includes water above unsaturated conditions and below saturated conditions the water table and seepage from springs etc Indexing Valve a device also called a K rain valve which allows for up to 6 separate land application areas to irrigated in sequence Irrigation Systems pressurised effluent dispersal systems such as proprietary Wasteflow or Netafim which deliver treated effluent to the sub surface typically 100 mm depth of the application area via valves pipes and emitters Infiltration the downward passage of water into the soil Land Application Area the land area over which treated sewage is applied Long Term Acceptance Rate LTAR the average sustainable rate effluent can be absorbed over the long term into a particular soil expressed in litres per square metre per day This rate is influenced by effluent water quality method of dosing the soil permeability and by the slime layer which builds up at the interface with the receiving soil Nutrients chemical elements that are essential for sustained plant or animal growth The major nutrients essential for plant growth are nitrogen phosphorus and potassium in excess nitrogen and phosphorus are potentially serious pollutants encouraging nuisance growths of algae and aquatic plants in waters and in the case of nitrate posing a direct human health risk Design
74. ecialised field Treatment performance is largely dictated by the time termed residence time that the primary treated effluent spends in the reed bed as this determines the contact time with the bacteria coated gravel and roots in the bed Installers and home owners should be made aware that installation of a reed bed will generally necessitate one more Council inspection with associated fees than other OSMS systems due to the delay in establishing the reeds The following provides a brief summary of the main aspects of design that need to be considered when designing and constructing a reed bed for on site treatment of effluent A4 1 Minimum surface areas for Secondary and Partial secondary Treatment Due to the detailed level of monitoring data available for reed beds Davison et al 2002 Headley 2003 Council s OSMS Design Model permits the designer to install reed bed sized to achieve either secondary standard refer Section 6 3 of the main report or partial secondary effluent quality with the difference in treatment level related to the size of the reed bed According to the approach adopted by Council in the accompanying guidelines the area required for land application can be reduced by treating the effluent to a higher quality Reed beds which are not big enough to provide secondary standard effluent can be assigned an expected nitrogen reduction factor from the OSMS Design Model starting at a minimum of 20 nitroge
75. ected and maybe disabled by these medications Some types of pathogens e g viruses and helminths are able to survive outside the body for months refer for example to DLG 2001 OSRAS Handbook Appendix F Although soil often performs as a very good filter for pathogens there always remains some risk that pathogens can be transmitted from carelessly treated or inappropriately applied land application systems Based on available published information Byron Council expects that adherence to these Design Guidelines will ensure that risks posed to home owners and neighbours are kept to acceptably low levels However where designers have cause to reduce the recommended buffer distances refer Section 5 1 6 or where above ground application of effluent is proposed refer Section 7 designers are required to provide additional written consideration to the risks of pathogenic transport and potential infection by householders neighbours or downstream water users Design Guidelines for On Site Sewage Management for Single Households Page 7 Byron Shire Council Doc 491166 5 SITE AND SOIL ASSESSMENT Correct and accurate site assessment is critical to developing appropriate and sustainable sewage management systems The main aims of the site and soil assessment are to identify any constraints that may potentially limit the ability of the site to adequately deal with effluent and to determine the amount of suitable land available for land applic
76. ed stormwater controls must be installed and effluent will require adequate disinfection before being sprayed above ground B4 3 SURFACE DRIPPER UNDER MULCH IRRIGATION Surface dripper under mulch options are considered appropriate in some agricultural applications for example where dripper lines can be usefully placed under mulch between rows of trees in a Appendix B Land Application Systems Page B5 Byron Shire Council OSMS Design Guidelines Appendix B 487903 location remote from the house and waterways In these cases drippers are placed on the ground surface at the tree base organic mulch is placed over the dripper lines and a mound is usually placed around each tree to keep the water at the roots In some instances owners have also used this type of system to regenerate bushland areas Such situations even with appropriate warning signs are not suitable for children to play in In plantations provision should also be made to allow for disconnecting the irrigation line in times of heavy machinery use on the plantation to minimise pipe damage Surface dripper under mulch options may also be considered for rural domestic situations in Byron Shire In these cases higher maintenance and monitoring conditions than sub surface irrigation options will be required to ensure that the mulch remains in place over the drippers and that casual access by children vehicles and livestock is restricted by a vegetative border fence or similar
77. ed and submitted to Council as part of the on site system design Step 11 Select Disposal Area Slope Type Mounded bed Level bed with grass Step 12 Select Soil Texture In Root Zone oarse Sand C E Fine sand Sandy loams Loams Clay loams Silt Clay obt med beau Step 13 Select Land Application Type Step 14 Select Calculate Button Below Calculate Minimum Land Application Area i e Figure 4 Steps 11 15 Designer Input Sheet The calculated minimum land application area of 490m is based on the chosen input values The main factors which affect the land application area size are the number of people source inputs particularly from the toilet size of the block and treatment selected Appendix C User Manual for OSMS Design Model Page C10 Byron Shire Council Doc 487794 Significant reductions in land application area can be achieved by reducing source inputs e g composting toilet and by improving treatment especially where nitrogen is reduced e g by adding a reed bed or re circulating sand filter By utilising all of the source input reductions listed above the model will return a value of 192 m as a minimum final land application area Note though that in this eventuality your irrigation designer would need to consider whether to disperse the effluent using an ETA bed rather than SSI as such a small SSI field might be likely to become over saturated C6 Examples Using the Data Design
78. ed as a basis by the system designer to prepare an individualised management plan for each system Management plans shall include operation maintenance and service requirements of all components of the proposed sewage management system This information must be specific to the particular system proposed and provide all necessary instructions for the occupier owner or service personnel to manage the system properly including an emergency action plan in the event of a breakdown Generic reports irrelevant to the site or type of system installed will be rejected A clear maintenance schedule shall be included in the Management Plan stipulating the type of system and its components including treatment device and land application area the system Responsibilities for undertaking inspection and maintenance tasks i e owner or servicing agent and specific time frames or conditions for servicing the various components must be provided Where possible component manufacturers and the service agents who will be responsible for maintenance of the system must also be nominated along with contact details It will be a condition of approval that the completed management plan shall be stored and or displayed in an appropriate place for the benefit of current and future occupiers owners and service personnel A final inspection will not be granted unless the service schedule is displayed and applications which do not provide management plans will be rejected
79. ed to accompany composting toilets involves the greywater being collected in a collection tank minimum size 1800 Litres before being dispersed in a sub surface evapo Appendix A to Design Guidelines Treatment Systems Page A11 Byron Shire Council OSMS Design Guidelines Appendix A 487879 transpiration absorption ETA bed The size of the greywater land application area will vary depending on wastewater loading and treatment level and is to be calculated using Council s OSMS Design Model In general the size of land application area required for greywater will be less than that required for combined blackwater and greywater systems due to the lower nutrient and hydraulic loadings of greywater alone this can be adjusted as an input in the OSMS Design Model A7 Separate Systems versus Combined Systems There are differing views on the desirability of separate or combined on site wastewater treatment and disposal systems The usual split separates greywater from blackwater Some experts advocate an all waste system in preference to separately treated greywater and blackwater because of the increased clogging which occurs with greywater alone due to its higher C N ratio generating polysaccharides Laak 1986 cited in Patterson 1994 The use of compost toilets presupposes a separate greywater system There are situations where the design of the structure and the characteristics of the land require two systems which may or may not
80. ed to the treatment system Reduced water consumption has been assumed and the dwelling will be fitted with standard water saving devices Recent soil sampling revealed a deep well structured clay loam and the water table was not detected during site investigations despite a sampling bore depth of 3m The surrounding area is mapped Morand DLWC 1994 as deep well structured red krasnozem soils on basalt parent material No permanent or intermittent waterways lie within 100m and there are no licensed bores within 250m of the proposed dispersal area Wastewater treatment is to be AWTS and subsurface irrigation is to be installed to distribute the treated effluent to a small banana planting on the property Appendix C User Manual for OSMS Design Model Page C7 Byron Shire Council Doc 487794 Method Starting at the top of the Designer Input Sheet the above details are entered in the appropriate cell reference or selected from list boxes in a series of clearly identified steps see Figures 1 4 Step 1 Enter the number of bedrooms 4 at cell ref M3 Step 2 Enter the property size 10 000 at cell ref M4 Step 3 Do not change waterway buffer type in select box because in this instance there is no nearby waterway Step 4 Leave enter within buffer distance cell ref M9 at default value 100m this value would only be changed if the distance from a nearby waterway is less than the default value In th
81. either by boring or trenching If significant differences are found in the first two profiles more sampling should be undertaken in order to establish the approximate boundaries of the various soil types Soil profiles should be examined to a depth of at least 1 2 m or deeper if changes in soil colour or texture are still being noted at the base of the hole Unless there are less permeable layers found during the profiling samples from around 0 4 m depth and around 1 0 m should be collected for detailed textural assessment either by an independent geotechnical laboratory or by a skilled practitioner A single sample from around 0 8 m depth in the centre of the proposed land application area may be acceptable in deep krasnozems sands or particularly evenly graded soils Soil texture and structure determine the soil s ability to accept effluent which in turn determines the appropriate effluent loading rate For example highly dispersive soils are problematic due to the damaging effect that excessive sodium can have in destroying the soil structure leading to a decrease in soil permeability and very low effluent loading rates are therefore recommended for highly dispersive soils refer Section 8 Designers should also be aware that even though they are not classified as highly dispersive krasnozem and many other volcanic derived soils in this area are prone to exhibiting reduced permeability after prolonged contact with highly sodic sewage effluen
82. em Maintenance Reporting Checklist 1 AWTS Systems Name and Contact Details of Service Provider Client Name Client Address Client Phone No Type of System Installed Components Installed AWTS sand filter etc Date installed commissioned if known Date of Service AWTS Service General Odours Access OK Restrictions Caps fitting Electrical Electrical circuitry Working Signs of wear Enclosures adequate Plugs and leads OK Alarm Systems Lights and or buzzer functioning Level sensors Air blower s Pressure in Kpa working adequately below original pressure setting Overheating y n Noisy y n Air filters blocked and cleaned functioning need replacing Vents and valves clear clear partially blocked all blocked Aeration pattern even restricted Transfer pumps Sludge return pump good pressure low pressure not functioning Irrigation pump good pressure low pressure not functioning Pump 3 good pressure low pressure not functioning n a Bearings OK Seals OK Septic Chamber Sludge Accumulation High med low Pumpout required Inlet junction clear y n Sludge Return system working slightly blocked blocked Odour none low strong Activated Sludge Systems SV30 test pH Water clarity clear coloured turbid Decanter operating yes no comments Disinfection Chamber Tablets remaining Tablets added Free chlorine measured mg L Problems noted and action taken
83. ends the use of solid polyethylene troughs for sand filters Unreinforced and or light weight flexible plastic liner e g builders plastic will not be accepted due to the high failure rates Appendix A to Design Guidelines Treatment Systems Page A6 Byron Shire Council OSMS Design Guidelines Appendix A 487879 and relatively short life expectancy commonly experienced with sand filters founded on these types of liners Finally sand filters are prone to clogging in their upper layers depending on effluent quality dosing rates and the coarseness and cleanliness of the sand media It is essential that sand filters are able to be accessed for regular maintenance Byron Council also strongly recommends that sand filter designs incorporate a means of monitoring the effluent level and quality A4 Reed Beds Constructed Wetlands Constructed wetlands or reed beds comprise a sealed basin containing gravel in which primary treated effluent is kept slightly below the surface of the gravel substrate The effluent is biologically treated as it moves slowly through the root zone of densely planted wetland plants usually reeds rushes but can also be shrubs or trees in gravel In order to minimise the risk of infection and disease through contacting the effluent reed beds should be constructed in a way that keeps the top of the effluent at least 5 cm below the top of the gravel bed The design of reed beds for sewage treatment is a sp
84. eria protozoa and viruses Percolation a general term describing the downward rate of water movement through a soil or through a biological mat within an effluent dispersal system Permeability a calculated value derived from the rate at which a head of liquid is absorbed into soil usually measured in m d as Saturated Hydraulic Conductivity Ksat Primary Treatment In on site sewage management primary treatment is taken to mean the initial reduction of suspended solids and organic matter from the household by means of settlement anaerobic digestion and or floatation in septic tanks or the primary settling chambers of AWTS Reed beds see Constructed Wetlands Run on surface water flowing on to an irrigation area because of run off occurring higher up the slope Scum the floating material which accumulates above the more liquid layer in a septic tank or other primary treatment device Scum forming material includes oils grease soaps and plastics Secondary Treatment For the purposes of these Design Guidelines the term secondary treatment applies to systems which can produce effluents containing no more than e 20mg L BOD e 30mg L Total Suspended Solids e 30 mg L Nitrogen e 10 mg L Phosphorus Septage The semi liquid material that is pumped out of septic or interceptor tanks consisting of liquid scum and sludge Septic Tank effluent storage container in which primary treatment of household effluent occurs under an
85. ers are seasonally close to the ground surface Besides the generic advice above the edges of mounds should be regularly checked to make sure that effluent is not breaking out of the mound edges rather than through the base Where the mound is fitted with observation ports the levels of effluent within the mound should be regularly checked to ensure that it is not building up and that the effluent is being evenly distributed within the mound Appendix G to Design Guidelines System Management Plan Page G8 Byron Shire Council OSMS Design Guidelines Appendix G 487883 G3 2 3 Evapotranspiration Absorption ETA Beds Evapotranspiration absorption ETA beds are essentially shallow trenches which encourage much better uptake of wastewaters and nutrients by plants grown into the bed ETA beds should be regularly harvested and plants replaced if required at regular intervals e g by mowing or pruning to encourage young growth G3 2 4 Sub surface Drip Irrigation Systems Sub surface drip irrigation SDI is a form of pressurised effluent dispersal in which the irrigation lines are buried 100 mm below the ground surface and effluent is emitted through spaced emitters SSI systems need to be flushed and maintained at no more than three monthly intervals using the checklist provided in Appendix F as a guide Annual servicing must include flushing of lines to remove solids that may block emitters G3 2 5 Surface Irrigation Syste
86. esign life of 15 years and or c the owners prefer to follow a philosophy of total reuse and sustainability and the designer believes that the land application area is not sufficient to provide this A separate document is being prepared by Byron Shire Council to provide a detailed explanation of how the Design Model works In the meantime it is suggested that most users will find sufficient information in the following description and worked examples to understand how to apply the model to proposed applications C3 Model Function Description The model calculates the minimum land application area required based on Hydraulic loading Total Phosphorous TP loading Total Nitrogen TN loading The largest of these areas is selected as the minimum sustainable area in which the soil crop will continue to polish and re use water amp nutrients in the effluent The model considers the treatment disposal process in a series of compartments or sub models This can be described as shown in Figure C1 Appendix C User Manual for OSMS Design Model Page C3 Byron Shire Council Doc 487794 Primary Treatment e g Septic or sullage tank AWTS Disposal Source re use area e g Household ETA beds hydraulic amp SDI fields Tertiary Treatment e g UV disinfection nutrient output Secondary Treatment e g AWTS Sand filter Reed bed Figure C1 Schematic of typical On site Sewage Management S
87. et periods These Design Guidelines do not therefore mandate that wet weather effluent storage must occur in single domestic installations but designers should consider wet weather storage a useful potential tool for improving environmental security on highly constrained sites e g flood prone lands or those over shallow groundwaters 6 5 4 Holding Tanks Pump Wells Many modern OSMS systems require pumping effluent to or from various components and this generally necessitates either an internal or external pump well Pump wells also commonly referred to as holding tanks or collection wells enable the storage of effluent until it reaches a pre set level in the tank at which time a pump is activated and the accumulated effluent is pumped through to the next component or the land application system The sizing of pump wells shall be in accordance with the advice provided by NSW Health in their Septic Tank and Collection Well Accreditation Guideline refer Section 1 4 for download address and provide sufficient storage space for at least seven days accumulated effluent in case of pump failure or blockage Smaller holding tanks are acceptable for dosing siphons which have no opportunity for mechanical break down Audio and or visual alarms must be installed in a manner that will alert the homeowner to the presence of a high level condition in the tank Backflow prevention devices must also be installed where appropriate 6 5 5 Component Ove
88. f the service An owner funded contract should exist between the Council authorised service provider and the owner of the AWTS G3 1 4 Sand Filters Sand filters work by dosing an enclosed sand column with effluent As the effluent moves past the sand grains it is treated through contact with the micro organism which coat the sand grains Operation amp Maintenance e Service provider to check and service pumps and other mechanical parts every twelve months e Home owner and service provider to check for slime or algae build up in intermittent single pass sand filters and remove if necessary every three months Appendix G to Design Guidelines System Management Plan Page G6 Byron Shire Council OSMS Design Guidelines Appendix G 487883 e For most heavily used systems or those working under adverse circumstances sand may need to be replaced every decade or so check manufacturer s recommendations G3 1 5 Reed beds Constructed Wetlands Reed beds comprise tubs filled with gravel into which reeds or in some cases shrubs are planted Effluent is biologically treated as it moves slowly through the root zone of the reeds Providing reed beds are properly designed and constructed they require minimal maintenance Harvesting of reeds while not absolutely necessary does promote fresh green growth and thus enhance a reed bed s aesthetic appeal whilst at the same time increasing nutrient removal This job is easily perfo
89. ghly Waterlogged impermeable soils high 10 000 reactive watertables Eltham el Red Basaltic Locally waterlogged flood hazard proximity to 10 000 streams Ewingsdale ew Red Basaltic High permeability but mass movement hazard 10 000 near drainage lines waterlogging on lower slopes Mount Burrel mb Red Basaltic Dark Steep slopes mass movement May need 10 000 Basaltic benching and or SDI on slopes Minyon mi Sandy Clayey Steep slopes rockiness seasonal 8 000 Duplex waterlogging and shallow soils all localised Mullumbimby mu Alluvial clays Flood hazard seasonal waterlogging high 10 000 watertables May need mounds Myocum Alluvial clays Flood hazard seasonal waterlogging high 10 000 watertables May need mounds North Casino jnc Alluvial highly Shrink swell soils localised waterlogging and 10 000 reactive high watertables Nightcap ni Varied includes Red Steep slopes mass movement rockiness 8 000 Basaltic Clayey Duplex Nimbin Rocks Nr Steep thin volcanic Severe limitations for development on cliff soils footslopes Not suitable for OSMS Rosebank Ro Red Basaltic Steep slopes mass movement May need 10 000 benching and or SDI on slopes Terania te Alluvial varied not Close to watercourse flooding stream bank 10 000 highly reactive and eroslon slumping doesn t easily fit Great Soil Group or profile categories Tuckean tu Humic Gley Unsuitable for effluent dispersal Tyagarah ty Alluvial
90. h clay stain bolus just coherent v sandy to touch SSES SSC sand grains ee visible E bolus coherent fine sand can be felt and 2 Sandy loams Fine sandy loam heard when manipulated clearly seen 13 25 under hand lens Light sandy clay strongly coherent bolus sandy touch med 20 25 loam size sand grains easily visible bolus coherent spongy smooth not sandy EECH silky feel when manipulated SH bolus coherent and slightly spongy fine Loam fine sandy sand can be felt and heard when 25 3 Loams manipulated coherent bolus very smooth to silky when Silt loam manipulated 25 strongly coherent bolus sandy touch med Sandy clay Igam size SCH grains in finer malri aapa Clay loam coherent plastic bolus smooth 38 50 EE Silty clay loam oe smooth bolus plastic and silky to 38 50 Fine sandy clay coherent bolus fine sand can be felt and 38 50 loam heard when manipulated Sandy clay plastic bolus fine to med sands seen felt 50 75 or heard in clayey matrix lastic bolus smooth and silky to 50 75 any clay Ronit lastic bolus smooth to touch slight 50 75 SES Light clay E to shearing between eh and forefinger plastic bolus smooth to touch slightly 75 Light medium clay greater resistance to shearing between thumb and forefinger plastic bolus like plasticine amp can be gt 75 Medium clay moulded into rods without fracture some 6 Medium to resistance to ribboning shear heavy clays Smooth plastic bolus like stiff plasticine
91. he base and around inlet and outlet fittings Rectangular troughs are preferred due to the minimisation of dead spots where little effluent circulation occurs however they are less stable on steeply sloping sites Round troughs are stronger and better on steeply sloping land The edge lip of the reed bed liner needs to be raised and constructed in such a way that upslope surface runoff is diverted around the bed A minimum lip height of 100 mm above ground level is usually required in reed beds in Byron Shire in order to prevent ingress of runoff Diversion drains or swales may also be required A stronger higher lip 150 mm is required for systems installed in Appendix A to Design Guidelines Treatment Systems Page A8 Byron Shire Council OSMS Design Guidelines Appendix A 487879 slopes of gt 10 Internally Council requires a minimum free board of at least 100 mm from the lip of the liner to the gravel surface with effluent remaining a further 50 mm below the gravel surface to provide emergency storage for wet weather periods or pump failures A4 3 1 Hydrostatic Testing of Liners Reed bed systems often fail due to leaks in the liner In many cases a slow leak is not detected until household inputs cease for a protracted period e g when the homeowners go on holiday for a couple of weeks and return to find that their reeds have all died To avoid this situation Byron Shire Council strongly recommends that a 24 hour hydrosta
92. he purposes of these Design Guidelines the term secondary treatment applies to systems which produce effluents containing less than e 20mg L BOD e 30mg L Total Suspended Solids e 30 mg L Nitrogen e 10 mg L Phosphorus Source Dept Natural Resources Interim Code of Practice for On site Sewerage Facilities 1999 It is noted that the above performance standard is from Queensland and that the equivalent design standard in NSW does not provide criteria for nutrients but the above criteria is nonetheless offered in these Design Guidelines for additional guidance Council acknowledges that there are smaller treatment system options e g smaller scale reed beds which will significantly improve the quality of effluent but wouldn t necessarily reach the secondary performance standards listed above For the purpose of these Design Guidelines these options are termed partial secondary treatment systems refer Glossary for definitions The minimum standard of treatment generally accepted for blackwater inclusive OSMSs in Byron Shire is to a partial secondary standard which achieves a 20 reduction in total nitrogen The choice of a treatment system to achieve secondary or partial secondary effluent quality at any given property will involve balancing the strengths and weaknesses of the available treatment options summarised in Table 8 and discussed in more detail in Appendix A Constrained land application areas e g withi
93. hen assessing the above and related issues The Design Guidelines rely heavily on both the NSW Environment and Health Protection Guidelines 1998 and Australian Standard AS NZS 2000 and designers are expected to understand and follow these two documents closely Where conflicts or ambiguities arise between the two external documents and these Design Guidelines the advice in the Design Guidelines shall prevail Design Guidelines for On Site Sewage Management for Single Households Page 1 Byron Shire Council Doc 491166 For further advice on providing for appropriate OSMS on subdivisions designers are required to refer to the Byron Shire Rural Settlement Strategy BSC 1998 if ambiguities arise between these two documents the Settlement Strategy takes precedence over these Design Guidelines There are particular difficulties involved in developing on site wastewater solutions in urban areas and these are recognised in Council s Policy 5 59 On site Sewage Management Systems in Urban Areas If a home owner wishes to treat or utilise sewage in an urban area these Design Guidelines should be followed in conjunction with the the above named Policy If ambiguities or conflicts arise between the two documents regarding an application in an urban area the advice set out in the Policy shall take precedence Council has not yet developed design guidelines for larger on site sewage management systems e g for cluster dwellings commerci
94. ia gov au NSW Department of Local Government at www dig nsw gov au an overview of the Department e on site sewage management programs to improve health and environment A very useful document provided by DLG is the On site Sewage Risk Assessment System which is available on line from www dlg nsw gov au dlg dighome dig_osras asp NSW Department of Health at www health nsw gov au public health ehb general Information on the accreditation of sewage management facilities by NSW Health is available on www health nsw gov au public health ehb general wastewater wastewater html Byron Shire Council website at http www byron nsw gov au health_and_ compliance Byron Shire Council s On Site Sewage Management Strategy 2001 available from Council website cited above Byron Shire Councils Home owners guide to on site sewage management 2001 A simplified or plain English version of the design guidelines available from Council website cited above BSC s Byron Rural Settlement Strategy 1998 Design Guidelines for On Site Sewage Management for Single Households Page 3 Byron Shire Council Doc 491166 2 STEPS REQUIRED FOR PREPARING AN OSMS DESIGN An OSMS generally consists of three main parts the wastewater source treatment components and a land application area for the final reuse or disposal of the treated effluent These components are represented graphically in Figure 1 SOURCE TREATMENT DEVICES LAND APPL
95. immediately Additional information should be added by system designer as appropriate Appendix G to Design Guidelines System Management Plan Page G5 Byron Shire Council OSMS Design Guidelines Appendix G 487883 G3 Maintenance and Care For Your System G3 1 Treatment Systems G3 1 1 Septic Sullage Tanks A septic blackwater and greywater or sullage greywater only tank operates as a stilling pond and anaerobic digester When the wastewaters enter the tank they are allowed time to settle out solids which fall downwards to join the sludge on the base of the tank and oils and greases which rise up to form part of the crust at the top of the water column For this to happen it is vitally important that sufficient liquid volume is maintained in the tank by pumping it out regularly and that the microorganisms in the tank are not killed off through inappropriate inputs Operation amp Maintenance e The householder should check the depth of the crust and the sludge regularly at least once or twice per year refer attached sheet for instructions e The sludge which builds up in the tank must be pumped out when it occupies more than a third of the tank s volume usually every 3 to 5 years e Do not flush tampons condoms or other indigestible inorganic material into a septic tank Avoid introducing bleach and chemicals harmful to the anaerobic microorganisms e f crust above the fluids becomes thinner than 2 3 cm or thic
96. ing of each treatment system is provided in Appendix A Designers are also strongly encouraged to do further reading and research e g Crites amp Tchobanoglous 1998 Metcalf amp Eddy 2002 to ensure that they understand all relevant aspects of all treatment systems under consideration Applications based on innovative designs or emerging technologies are encouraged provided sufficient technical justification can be provided to support their stated performance expectations Designers and prospective owners should be aware that each system will require some monitoring and maintenance specified by Byron Shire Council in the Approval to Operate for that sewage management system refer Appendix G Highly mechanised systems such as aerated wastewater treatment systems and sub surface irrigation fields generally have quarterly maintenance requirements whilst most other systems need to be checked and maintained by a suitably skilled service provider at least once a year Designers and prospective owners should ensure that they are aware of the monitoring and maintenance requirements and consider their costs when choosing the system 6 1 SOURCE CONTROL 6 1 1 Water Saving Devices The size and cost of treatment and land application systems are directly related to the volume of effluent that must be dealt with Thus activities or devices that minimise the generation of effluent at the source can often bring about a significant reduction in the cost a
97. ing of effluent For these reasons ETA beds are discouraged in Byron Shire If ETA beds are to be installed the following design features are required unless sufficient justification is provided for alternative designs gt Design and installation must comply with the requirements of AS NZS1547 2000 gt Distribution of effluent is to be via a minimum of two distribution pipes per 1 5 m wide bed with one extra pipe required for each additional metre in width gt Distribution pipes are NOT to have geotextile socks fitted to them as this may lead to the pipes clogging gt The beds must be installed completely flat and checked by means of laser level or super saturating the ground and adjusting any puddle areas gt Maximum length of each bed shall be 20m and central feed systems are preferred gt The distribution system must be designed and installed to ensure even distribution throughout the beds Splitter boxes must be accessible and stably installed Distribution pipes must be installed absolutely flat and should be drilled on the sides rather than the bases so that effluent wells out evenly rather than seeps out the first few holes gt Monitoring ports e g slotted and capped PVC pipe must be installed in at least 2 locations per bed Appendix B Land Application Systems Page B3 Byron Shire Council OSMS Design Guidelines Appendix B 487903 gt Beds must be mounded and grassed to reduce rainfall penetration and encour
98. ir poor nitrogen removing performance though good nitrifying capacity This can be remedied either by deepening the filter to ensure an anaerobic zone or by recirculating a proportion of the highly nitrified sand filter effluent back over the sand filter or into the carbon rich septic tank for rapid denitrification USEPA 2003 Recirculating sand filters usually provide better N removing capability and better overall treatment performance than single pass sand filters However they are more expensive and complicated to construct and require additional pump power More detail on the design and performance of sand filters is provided in Appendix A Operation and maintenance requirements for sand filters are provided in Appendix G 6 3 3 Subsurface Flow Reed Beds Constructed Wetlands Constructed wetlands or reed beds comprise a constructed impermeable basin in which water or effluent is kept slightly below the surface of a gravel substrate which supports the growth of wetland plants usually reeds but can also be shrubs or trees The effluent is biologically treated as it moves slowly through the root zone of the wetland plants Reed beds are an increasingly popular type of secondary treatment device due to their aesthetic appeal their reliable treatment performance capacities once the reeds are fully established and their somewhat lower construction costs and maintenance requirements compared to other options They are also passive devices n
99. is instance there is no nearby waterway SI File Edit View Insert Format Tools Data Window Help tab color D Gebai la 2 B S MP Be Zu Ae WI ei a l Times New Roman Ca B 7 U 2 P S amp S Bs g ER SEI e A amp d N14 X i E F G H I J K ie M Byron OSMS Design Model Disposal Area Calculator Step 1 Enter Number Of Bedrooms gt gt d 4 W8 Step 2 Enter Blocksize gt gt gt 10000 Step 3 Select Waterway Buffer Buffer to permanent water Buffer to intermittant water 9 gt ae Step 4 Enter Within Buffer Distance gt gt gt 100 Figure 1 Steps 1 4 Designer Input Sheet Gol IO Ilka lb Win Step 5 Select water supply from list box roof water harvesting std water saving devices 115L pp day 115L pp day is the predicted water use factor where rain water is harvested water conservation devices are fitted and all facilities are connected to the treatment system Step 6 Select facilities water usage from list box tick each of the facilities in the list box in this example Step 7 Select treatment method from list box AWTS Appendix C User Manual for OSMS Design Model Page C8 Byron Shire Council Doc 487794 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 sc aT Step 7 Select Treatment Method Figure 2 Steps 5 7 Designer Input Sheet Step 8 Reticulated supply bore spring creek 180L p d Step 5
100. is provided for the proposed system and application area Whatever method is used to design the OSMS system and regardless of the model used to calculate the land application area size the designer remains responsible for using their knowledge and experience to reject or modify any systems which will not adequately treat and disperse the effluent over the fifteen year design lifetime of the system C1 1 Model Availability amp Features A standard 3Mb or Zipped 0 7Mb version of the model can be downloaded from Byron Shire Council s website at www byron nsw gov au The Design Model sits within a Microsoft Excel Workbook and comprises three linked spreadsheets a simple data input worksheet a data report worksheet and the model worksheet The first worksheet allows users to record relevant site parameters and run the model including the print out from the data report page without needing to work through the more complex model spreadsheet Experienced OSMS Designers can apply to Council for an unlocked version of the model on CD Rom which allows more direct manipulation of certain elements of the model In all cases designers can experiment with different treatment methods and land application options to achieve the desired results However deviation from standard parameters e g volumes of household effluent generation default nutrient reduction rates for particular technologies must be declared by designers with justification whe
101. ken On Site Sewage amp Wastewater Management Strategy E3 Byron Shire Council OSMS Design Guidelines Appendix E Treatment Service Checklist 422469 On Site Sewage amp Wastewater Management Strategy E4 Byron Shire Council OSMS Design Guidelines Appendix F_Land Application Service Checklist 459030 APPENDIX F Land Application System Service Checklist On Site Sewage amp Wastewater Management Strategy F1 Byron Shire Council OSMS Design Guidelines Appendix F_Land Application Service Checklist 459030 Appendix F OSMS Land Application System Maintenance amp Reporting Checklist Name and Contact Details of Service Provider Client Name Client Address Client Phone No Type of System Installed Components Installed AWTS sand filter etc Date installed commissioned if known Date of Service Absorption Trenches ETA Beds Odours Evidence of surcharging Fluid levels OK Distributor system OK Stormwater diversion system functioning Irrigation Systems Pump s Control System Filters Irrigation field Pressure OK Bearings OK Electrical system OK Enclosures adequate Plugs and leads OK Level sensors clean and operating well Alarm light and or buzzer OK Cartridges cleaned and or replaced Pressure gauges installed working Filter loss lt 70 KPA Location of irrigation field accurately known marked Scour valves opened and flushed gt 5 minutes Latera
102. ker than 10 15 cm investigate causes e g thin crust could be due to high throughflow of effluent or toxic materials in influent e Do not smoke near the septic tank when undertaking maintenance work due to possible risks from build up of flammable gases such as methane in confined spaces G3 1 2 Effluent Filters An effluent filter is a coarse screen filter that sits in the outlet of a primary treatment tank Effluent filters need to be maintained regularly to ensure that they function effectively An effluent filter which is not regularly cleaned will clog and potentially cause the tank to back up and overflow or otherwise might be responsible for high levels of solids being carried over to the next treatment component Effluent filters should be cleaned by the householder every few months and cleaned and serviced by a service provider at least once per year check manufacturer s recommendations Care should be taken when cleaning an effluent filter to avoid contact with the effluent and to clean hands and any affected clothes afterwards G3 1 3 Aerated Wastewater Treatment Systems AWTS s In accordance with NSW Health accreditation requirements most AWTS s require quarterly maintenance and servicing by a qualified service contractor usually the firm that supplied the unit A copy of a maintenance report based on the examples shown in Appendices E and F must be completed by the service provider and sent to Council within 14 days o
103. l lines open and flushed gt 5 minutes Evidence of blockages or surcharging Evidence of poor or excessive vegetation growth Warning signs in place Problems noted and action taken On Site Sewage amp Wastewater Management Strategy F2 Byron Shire Council OSMS Design Guidelines Appendix G 487883 Design Guidelines for On site Sewage Management for Single Households APPENDIX G Looking After Your On Site Sewage System OSMS Management Plan for Byron Shire Council OSMS Design Guidelines Appendix G 487883 On Site System Management Plan This section is designed to be used as a basis for On site Sewage Management System OSMS designers to provide a management plan for the homeowner s permanent use It is intended that the OSMS designer will fill in the appropriate sections remove any irrelevant components and add any relevant comments to make the management plan as comprehensive and useful as possible to the future homeowners It will be a requirement of consent that a management plan is provided with each design successfully submitted and a further condition of the Approval to Operate that s copy of the Management Plan is stored in an appropriate location within the home The following information is to be provided at the front of each management plan Street address Lot Deposited Plan Council reference no s if known Author and date of OSMS design document submitted to Council D
104. le care has been taken to ensure the information contained in this booklet is accurate No warranty is given that any of the information contained in this booklet is free from error misdescription or omission nor is any warranty is given that any component or system referred to in this booklet will meet any standard of performance or use Council expressly disclaims all liability in respect of anything done or omitted to be done by any person in reliance upon the contents of this booklet Any reliance on the information contained in this booklet shall be at the sole risk of the user and this information must not be relied upon in reaching a decision to purchase property Design Guidelines for On Site Sewage Management for Single Households Page ii Byron Shire Council Doc 491166 TABLE OF CONTENTS Lk INTRODUCTION Seege eseu EES deed DEENEN 1 1 1 Scope and Applicability es icctceee cece ciecee lected hednecbanceelecidl ria alot nnmn 1 4 2 G iding Princ ples ege ieee sec eebe 2 1 3 NSW Health Accreditation of OSMS Facilities ccccceeeeesseeeeeeeeseeeeeeeeeeeeeeeeneeeeeeeeneeeees 3 1 4 MORE ITOPIMAUION sisi tege caccunscdanctec nentaraaiaunadeauedsanzdauhcatenwcetatacbantcbansasunncuiviaasandandudesiadia 3 2 STEPS REQUIRED FOR PREPARING AN OSMS DESIGN ccccescessseeeeseeeeeeeeeseeeseseeeenseeeseeeseseeeenseeeeeiees 4 2 1 Recommended Design Steps ergeet gege 4 32 DESKTOP RESEARCH EE ar aa pea ame re a a oaa ea aaa a geg
105. liminary Step 1 Cells highlighted in blue or green may be altered by the user Blue cells are reserved for data entry of parameters most likely to vary between designs Cells highlighted in green are for data entry parameters unlikely to vary between applications so called default parameters Cells which are not for data entry but merely display calculation results are left un highlighted in black Some cells contain red dots these exact cells being reserved as data entry boxes to overwrite the calculation result in the adjacent box This allows users to perform limited customized calculations Appendix C User Manual for OSMS Design Model Page C11 Byron Shire Council Doc 487794 Select the Set Defaults button to return all previously entered data to model default values Step1 Select bedrooms from the persons bedrooms select box in this instance we know how many bedrooms the development will have 3 bedrooms in main home 1 bedroom for studio Step 2 Enter the number of bedrooms 4 at cell ref B5 for the main dwelling studio do not change default value at B6 Step 3 Select buffer to permanent waterway in select box because in this instance there is a permanent stream nearby Change buffer distance at cell ref D6 to 75 the default value is to be changed because at this stage of design the distance of a possible land application area from a nearby waterway is less than the default value of 100m
106. lines 1998 On Site Sewage Management for Single Households Dept of Local Govt Environmental Protection Authority NSW NSW Health Dept Land and Water Conservation Dept of Urban Affairs and Planning Emerson W W 1967 A classification of soil aggregates based on their coherence in water Aust J Soil Res 5 47 57 Gersberg R M Elkins B V Lyons R Goldman C R 1986 Role of aquatic plants in wastewater treatment by artificial wetlands Water Research 20 pp 363 367 Grant N and Griggs J 2001 Reed beds for the treatment of domestic wastewater CRC London Headley T 2003 Design models for the removal of BOD and Total Nitrogen in Reed Beds Proceedings On site 03 Conference University of New England Australia Edited by Robert A Patterson and Malcolm J Jones Metcalf and Eddy 2002 Wastewater Engineering Treatment and Reuse 4 Edition McGraw Hill publishers Morand D T 1994 Soil Landscapes of the Lismore Ballina 1 100000 Sheet DCLM Sydney Morand D T 1994 Soil Landscapes of the Tweed 1 100000 Sheet DCLM Sydney NDLG 2000 The Easy Septic Guide Developed by Social Change Media for the NSW Department of Local Government Northcote K H 1979 A Factual Key for the Recognition of Australian Soils Rellim Technical Publications PO Box 1619 Coffs Harbour NSW 2450 Patterson R 1998 Soil Capabilities for On Site Wastewater Treatment and Disposal Lanfax Laboratories Armidale NSW Reed S C Cri
107. ller aggregates particles fall off the original aggregate Class 4 No change to aggregate therefore non dispersive If any of the replicates are in Classes 3 or 4 then the soil shall be considered dispersive and the Soil Category should be considered Grade 6 as though for a Texture Grade of Medium to Heavy Clays refer Table 3 above and AS NZS1547 2000 for further information In such cases gypsum will need to be worked into the land application area at a predetermined rate in order to prevent soil structure degradation Further ameliorative measures such as the expansion of the land application area or provision of a larger reserve field is also likely to be required to compensate for the likely long term reduction in permeability in the land application area 5 3 SITE CONSTRAINTS AND POSSIBLE SOLUTIONS The information in preceding sections should be used to make an assessment of the proposed land application area s and to identify any constraints for treatment or dispersal of effluent Should any site or soil limitations be found applicants or their consultants must clearly report them in the assessment report highlighting all limitations and detailing the appropriate mitigation measures intended to be taken to address these limitations Tables 6 and 7 show some common site and soil constraints and the measures which might be employed to overcome them or ameliorate their effects Design Guidelines for On Site Sewage Management for Si
108. ls with the land application area to adsorb phosphorus over 50 years minus that expected to be taken up by plants refer Appendix C The land application areas calculated using these Design Guidelines and the Byron OSMS Design model assume that the site is not significantly constrained refer Section 5 Where OSMSs are to be installed on blocks which are constrained by one or more factors refer Section 5 ameliorative actions such as providing additional treatment or larger land application areas are likely to be required refer Tables 6 and 7 Note that very high treatment levels can in some circumstances enable the OSMS Design model to allow very small land application areas To ensure that enough area is allocated to safely disperse the treated effluent without leading to periodic super saturation a minimum area of 15 m bedroom 10 m person must be allocated for greywater only systems and 22 5 m bedroom 15 m person must be allocated for systems treating combined effluents including blackwater Note that these minimum land application areas are based on the assumption that the site has suitable soils light clays that the black water effluents are treated to at least partial secondary standard and that no constraints apply to the site If these conditions are not met a larger land application area will be required to provide an equivalent level of environmental security If using Councils Design Model the input worksheet output Co
109. lthough a number of systems using media other than sand e g styrofoam balls are available on the market Wastewater is applied to the surface of the sand or similar bacterial growth media through which it percolates vertically to a collection system at the base of the filter Figure A3 Micro organisms attach themselves as a biomat around each grain and biological treatment happens as the effluent contacts the biomats whilst trickling downwards through the media TO APPLICATION AREA Figure A3 Schematic of a typical sand filter installation There are two types of sand filter 1 single pass or 2 recirculating Single pass sand filters are those in which the effluent passes through the sand media only once before collection for dispersal Single pass sand filters may be designed with the effluent entering the sand filter passively under gravity i e whenever wastewater is generated in the dwelling or preferably intermittently applied by a pump or dosing siphon Recirculating sand filters are so named because the effluent is collected from the base and recirculated back through the sand greatly improving treatment and the opportunity for denitrification Recirculating sand filters usually exhibit significantly better N removing capabilities and good performance overall However they are more expensive and complicated to construct than the single pass sand filter require more power and are not yet widely known in our region S
110. lush pits must be provided to allow this regular flushing maintenance without causing pollution There are a number of different types of proprietary SDI systems on the market Council requires that all new installations use pressure compensated emitters and strongly prefers the use of non drain varieties Additional details regarding design and operation of subsurface irrigation systems is provided in Appendix B4 and operation and maintenance requirements are provided in Appendix G 7 4 SPRAY IRRIGATION Above ground spray irrigation requires prior tertiary disinfection of sewage NSW Health Within the Byron Shire spray irrigation of effluent is not favored due to public health risks from aerosol transmitted pathogens and the particular need to add toxic substances such as chlorine to disinfect the effluent before above ground release There may be some circumstances e g on larger agricultural holdings in which the proposed land application area is a considerable distance from any houses where spray irrigation may be accepted Refer Appendix G for maintenance requirements 7 5 SURFACE DRIPPER UNDER MULCH IRRIGATION Byron Shire includes productive farming area where effluent reuse can be particularly beneficial The irrigation of effluent by above ground drippers in plantations may be appropriate in some rural and reafforestation applications Surface dripper under mulch options may be considered for domestic situations in Byron Shi
111. m below the ground surface and effluent is emitted slowly and widely Sullage another term for greywater see definition above Tertiary treatment For the purpose of these Design Guidelines tertiary treatment involves disinfection of secondary treated effluent but may also include further post secondary treatment filtration and nutrient removal Transpiration the transfer of water to the atmosphere through plants Design Guidelines for On Site Sewage Management for Single Households Page 36 Byron Shire Council Doc 491166 12 REFERENCES AS NZS1547 2000 Australian New Zealand Standard On site domestic wastewater management Standards Australia amp Standards New Zealand Strathfield NSW 2135 amp Wellington NZ 6020 Beavers PD and Gardner EA 1993 Prediction of virus transport through soils In AWWA 15 Annual Convention Proceedings Gold Coast BSC 2003 Home Owners Guide to On site Sewage Management including Self Assessment Guidelines and Minimum OSMS Component Specifications Byron Shire Council Mullumbimby Crites R and Tchobanoglous G 1998 Small and Decentralised Wastewater Management Systems McGraw Hill Davison L Bayley M Kohlenberg T and Craven J 2002 Performance of Reed Beds and Single Pass Sand Filters with Characterisation of Domestic Effluent NSW North Coast NSW Department of Local Government s Septic Safe Scheme Lismore City Council Lismore Water Lismore NSW E amp HP Guide
112. may be used for effluent application However other types of fill with coarse fragments and located on steep sites are unsuitable for land application of effluent 5 1 13 Erosion Mass Movement The location and details of existing mass movement and erosion such as gullies slips and rills should be recorded on the site plan refer AS NZS1547 2000 To protect against future erosion adequate drainage controls must be undertaken to ensure that effluent is not concentrated within one location and upslope runoff is diverted around the land application area Particular attention should be paid to ensuring that on site systems in steep areas will not lead to slumping on slopes If in doubt seek suitably qualified advice 5 2 SOIL EVALUATION The relevant soil properties of each proposed land application area should be investigated and assessed in accordance with AS1547 and these Design Guidelines by a suitably skilled and qualified independent practitioner The assessment must contain an accurate estimation of the soil and sub soil characteristics The three key tests to be performed are e the manual bolus or ribbon test to determine soil texture e the visual test to determine soil structure e the modified Emerson Aggregate test to determine soil dispersiveness Soil evaluation needs to be focused on the proposed land application area as recommended in AS1547 2000 At least two soil profiles should be examined in each land application area
113. ment for land application areas for improved treatment Conversely the guidelines and model responds to higher development density by increasing the land application area requirements In effect the guidelines and model reflect the reduced environmental risk on larger allotments and it is therefore not as important to provide highly treated effluent on larger blocks There may be other reasons why high quality treatment is required in a particular situation e g public health risk but this is beyond the scope of the model and unusual circumstance need to be assessed on a case by case basis BSC acknowledges that this notion deviates somewhat from the principle of maximum re use espoused by the State Government guidelines E amp HP 1998 However BSC believes that the higher reliance on effluent polishing mechanisms in the soils surrounding the actual effluent dispersal area on suitable i e well buffered blocks is acceptable in view of the greatly reduced risks these applications pose to the environment The size of the Land Application Area allowed by the OSMS Design model should be seen as a minimum size for otherwise unconstrained sites and designers are encouraged to expand the size of the land application area or improve the effluent quality if a site constraints will reduce the overall environmental or public health security of the OSMS b they believe that the land application system will not be able to operate for a minimum d
114. miting the installation and operation of land application systems refer Table 6 5 1 2 Slope shape The shape of the slope may either assist or hinder drainage as shown in the following diagrams Best water shedding shape convex Worst water shedding shape concave Source AS NZS1547 2000 Concave shaped slopes are much more likely to have problems with effluent dispersal than convex shaped slopes because of the way groundwater is concentrated in them Additional cut off drains and diversion bunds may be used to ameliorate poor drainage conditions The reader is referred to the Australian Standard AS1547 2000 for more detailed diagrams of the various types of slope shape and their implications for OSMS Design Guidelines for On Site Sewage Management for Single Households Page 8 Byron Shire Council Doc 491166 It is strongly recommended that the site be surveyed to aid landform and slope assessment A minimum distance of 20 meters will be required to measure and determine the degree of slope and variations in slope around relevant parts of the property should be marked on the plan 5 1 3 Aspect Use a compass to ascertain the dominant direction that the proposed irrigation area faces North and northeast facing slopes are preferred due to greater exposure to sunlight hence higher evapo transpiration rates Refer to AS NZS1547 2000 for further advice 5 1 4 Exposure High exposure to sunlight and prevailing winds greatly
115. ms Surface irrigation systems are generally discouraged in domestic situations due to the ease of contact between effluent and humans or pets who may contact humans Besides the generic maintenance principles outlined above particular attention must be paid to ensuring that people especially children are not able to contact the effluent Unless prior agreements have been specifically made with Council refer to attached Council Approval effluent must be suitably disinfected before above ground irrigation occurs G3 2 6 Surface Irrigation Under Mulch Systems Surface irrigation under mulch systems are a type of hybrid between the two irrigation systems described above These systems are generally only appropriate in agricultural or remote locations when they are installed under dense tree plantings including orchards Besides the generic maintenance instructions described above it is important that the mulch covering the irrigation lines is regularly renewed to reduce the risk of plastic pipes moving or breaking down under the effect of ultra violet deterioration Particular attention must also be paid to ensuring that people especially children are not able to contact the effluent G4 Your Approval to Operate your OSMS Council approval to operate a system of sewage management is required under Section 68 F 10 of the Local Government Act 1993 and clause 45 of the Local Government Approvals Regulation 1999 Landowners
116. n be used with care and greater spacing on highly permeable sandy soils The sub surface drip irrigation dispersal method is discussed in the E amp HP Guidelines 1998 and AS NZS1547 2000 Pages 122 126 in some detail On some small and highly constrained sites it is sometimes advantageous to distribute effluent in carefully laid micro trenches These micro trenches comprise narrow shallow gravel filled trenches in which sub surface irrigation pipes are installed The advantages of micro trenches is that by shallowly laying them along the contour they can distribute effluent reliably evenly and intermittently using a dosing siphon or pump Assuming that stormwater is adequately diverted micro trenches provide a good opportunity for reuse by plants and only a low risk of effluent surcharging during wet periods Appendix B Land Application Systems Page B4 Byron Shire Council OSMS Design Guidelines Appendix B 487903 Laterals in gravel filled trenches are to be spaced 600mm apart unless otherwise justified Sub surface irrigation which is installed without the benefit of distribution trenching will be required to have a dripper spacing of 300 mm and will typically need to have three times the density of and linear length of pipework compared to trench based designs Sub surface irrigation systems must be designed and installed by suitably qualified persons and must be flushed to remove sediment slime at least once per year
117. n reduction Larger application areas are required for lesser treated effluents in Councils OSMS Design Model refer Appendix C Recent studies on the North Coast Davison et al 2002 indicate that a reed bed with a 5 day residence time will provide secondary treatment i e achieving BOD lt 20mg L TSS lt 30 mg L N lt 30 mg L A reed bed with a 5 day residence time will be also be assumed to remove a default value of 40 of the total nitrogen loading from applied effluent in Byron Council s computer model Reed bed designers are encouraged to seek higher default nitrogen reduction values for use in Councils OSMS Design Model by providing detailed monitoring results from installed systems Alternatively systems designed using the Kadlec and Knight DLWC Wetlands Manual 1998 methods will be accepted A reed bed with a 7 day residence time would be considered more appropriate in constrained sites e g application systems over shallow groundwaters or within 100 m of a waterway refer Table 8 Site Limitations Appendix A to Design Guidelines Treatment Systems Page A7 Byron Shire Council OSMS Design Guidelines Appendix A 487879 A4 2 Reed Bed Construction There are essentially five functional elements to a reed bed as shown in Figure A5 These are e the containment system also termed liner or skin the substrate or porous medium the macrophytes or aquatic plants the inlet structure and the outlet structure
118. n site owner built following a specific design plan or commercial units such as the Clivus Multrum Nature Loo and the Rota Loo purchased off the shelf All compost toilets in NSW must meet the NSW Health Department Waterless Composting Toilet Approval Guideline 1997 There are two basic types batch and continuous flow systems A diagram of a continuous flow type compost toilet is given in Figure A6 Appendix A to Design Guidelines Treatment Systems Page A10 Byron Shire Council OSMS Design Guidelines Appendix A 487879 Vent above roof line Room ventilated when seat open Pedestal Floor Compost Access Door through heap Excess Moisture Figure A6 Cross section schematic of a continuous flow type compost toilet Dry composting toilets require a carbon rich bulking agent such as wood shavings shredded leaves shredded paper or preferably a mixture of these which needs to be applied after each use of the toilet This bulking agent also covers the faecal material and aids in reducing any odours from the compost The toilets must be vented and some have mechanical ventilation to ensure good air flow around the compost heap After a period of time faecal and bulking material is decomposed into a friable humus like compost material which is removed from a door at the base of the toilet The use of a compost toilet will remove the toilet component from the wastewater flow of a dwelling or developmen
119. n stated buffer distances Section 5 1 1 or on poor soils or steep slopes will generally require higher levels of treatment or larger land application areas to ensure that pollution of waterways is avoided By reducing the concentration of nutrients and suspended materials the level of effluent treatment has a proportional impact on the size of the land application area required as calculated by the OSMS Design Model see Appendix C Homeowners and system designers have the option to choose better quality e g secondary treatment and small land application areas or lesser quality partial secondary treatment combined with larger application areas provided that the partial secondary treatment option achieves at least a 20 reduction in total nitrogen for blackwater inclusive systems Design Guidelines for On Site Sewage Management for Single Households Page 20 Byron Shire Council Doc 491166 Table 8 Strengths and weaknesses of secondary treatment systems Source Davison 2003 Reed bed Single pass Recirculating Performance criterion horizontal sand filter sand filter flow wetland Power required Yes Pump needed on Yes No flat ground Fall of site Any 1m fall if no Any Flat to pump moderate slope Surface area Small 4m person lt 3m person 4 6m person Maintenance High Owner can do Owner can do Owner can do quarterly checks annual checks annual checks annual conta
120. n systems by using intermittent loading Appendix B Land Application Systems Page B2 Byron Shire Council OSMS Design Guidelines Appendix B 487903 Careful consideration needs to be given to the installation of this type of effluent dispersal system due to the high rainfall of this region difficulties in construction and the adverse environmental consequences of system failure Poor success rates have been experienced with mounded dispersal systems in Byron Shire and for this reason Byron Shire Council does not recommend their use If a mounded application bed is proposed the design and sizing of each mound shall be in strict accordance with AS NZS 1547 recommendations If they are to be used mounded beds must be carefully constructed and turfed to prevent erosion and to maximise shedding of rainfall off the bed The down hill side of the mound should not exceed a slope of 1 in 3 83 which can become difficult to achieve even on moderately sloping sites To enhance maintenance capabilities and to assess the risk of surcharging or other forms of failure Byron Shire Council requires that observation ports e g made from capped and slotted 50 mm PVC riser pipes are placed in at least 4 positions per mound to enable regular evaluation during maintenance visits B3 Evapotranspiration Absorption Beds ET amp ETA beds An evapotranspiration ET bed disperses effluent somewhat like a sand and gravel sponge with a large surface area a
121. n the design is considered for approval by Council The OSMS Design Model offers common tools and features such as list boxes check boxes and buttons from which input values may be chosen Some of these features are reproduced in this text and in many cases the text of the attached Design Guidelines We recommend that the examples provided in Section C3 be attempted by all users in order to become familiar with the operation of the model C2 Model Philosophy The following sections of Appendix C provide a description of the model philosophy as well as details of model function including data required for correct model operation In designing an OSMS it is important that the designer understands the approach used to estimate the sustainable application rates of treated effluent and the nutrient loads contained in the effluent As discussed in Section 1 2 of the attached Design Guidelines a core objective of the National Water Quality Management Strategy 1997 which all State and Local Government water management is required to follow is to enhance individual and community well being and welfare by following a path of economic development that also safeguards the welfare of future generations The Strategy NWQMS 1997 further requires that the need to develop a strong growing and diversified economy which can enhance the capacity for environmental protection should be recognised In developing its On Site Sewage Manageme
122. nd shallow depth sealed at the base and sides to prevent absorption into surrounding soils Whilst sealing the base is potentially advantageous because it limits pollution of neighbouring soils and underlying groundwater the high rainfall and limited evapotranspiration experienced in the North Coast region means that sealed base ET beds are prone to becoming over filled and periodically surcharging over downstream areas during the wet season Evapo transpiration absorption ETA beds are essentially the same as ET beds but are not sealed at the base and sides ETA beds allow effluent to be taken up by evaporation and transpiration mechanisms above the bed as well as allowing some of the effluent to percolate through the permeable base of the bed As well as providing treatment and reuse of a proportion of the effluent through evapo transpiration ETA beds can be quite robust and needing relatively little maintenance when properly designed and installed However ET and ETA beds are relatively expensive and difficult to install properly and they consume large volumes of non renewable imported resources particularly sand gravel and transportation energy In operation it is extremely difficult to achieve even distribution of effluent over the full width and length of the bed for maximum uptake by plant roots and both ET and ETA beds also suffer from a propensity to fill up with rain water during wet periods with consequent risk of periodic over topp
123. nd size of the OSMS Careful consideration should therefore be given to the water consuming appliances used in the household e g washing machines flush toilets shower heads leaking plumbing Installing water efficient fittings and appliances in the household to minimise wastewater generation rates can achieve significant reductions in the size and cost of treatment and land application components of OSMS Installing composting toilets rather than flushing toilets can achieve the greatest single reduction The designer is then required to refer to AS1547 2000 to determine appropriate wastewater generation rates based on what the household water source will be e g tank water or reticulated supply and whether water saving devices are installed Note that Council will need to confirm that any water saving devices claimed in the design are installed when it inspects the OSMS refer Section 10 The daily volume of household effluent that the OSMS will need to cater for is then estimated by multiplying the number of persons expected to reside there see above with the expected effluent generation rate from AS1547 2000 These calculations are performed within a subroutine of the Byron OSMS Design Model refer Appendix C 6 1 2 Waterless Compost Toilets Compost toilets significantly reduce the amount of treatment required for sewage by eliminating faeces and urine from the wastewater stream at the source By eliminating the need for toilet fl
124. nes System Management Plan Page G11 Byron Shire Council OSMS Design Guidelines Appendix G 487883 Tank diagnosis Healthy tank Scum mark Sludge mark Sick tank Bacteria have died Needs pumping out filling with clean water and addition of lime Absent scum mark Sludge mark Sick tank Needs pumping out and trench may be blocked or waterlogged or failed Scum mark Sludge mark Appendix G to Design Guidelines System Management Plan Page G12
125. ngle Households Page 15 Byron Shire Council Doc 491166 Table 6 Limiting Site Conditions for Land Application Areas and Suggested Solutions Suggested solutions to limitations Enhanced treatment sub surface Slope irrigation over larger area Irrigation For steeper ground use Slopes gt 15 with wider spaced SDI emitters narrow ETA beds or SSI along contour for very steep or highly constrained sites Stormwater diversion bunds above Landform Ge drainage concentrating concentrating areas larger P application area Pos GE Land application area faces SW or GE Shade plants trimmed often p R quadrants and or trees sheltering from expand land application area or to sun enhances sun wind improve effluent evapotranspiration rates Site Feature Examples of limiting conditions lt 100m to permanent surface water OR lt 250m to domestic groundwater wells OR lt 40m to other waters e g farm dams intermittent waterways dry gullies and Distance to Water Body drainage channels and man made features OR Potential for polluting lt 6m if up gradient and lt 3m if down downstream waters or gradient of property boundaries neighbouring properties swimming pools driveways and buildings In the case of ETA beds lt 12m if up gradient and lt 6m if down gradient of property boundaries but 6m 3m as above for pools etc upstream lands Application Area subsurface drainage Land application area below 1 in 20 Pump and electrical
126. nt Strategy Byron Council is making a genuine effort to reflect the principles set out in the National Water Quality Management Appendix C User Manual for OSMS Design Model Page C2 Byron Shire Council Doc 487794 Strategy within the OSMS Design Model balancing environmental public health and economic imperatives Council recognises that many waterways with Byron Shire are stressed by higher than natural nutrient levels and that there is a need to reduce current pollution loads from many sources including on site sewage agricultural inputs and centralised sewerage outfalls Council also recognises that safely treating and dispersing household effluent tends to be an expensive but vitally important process the risks posed by each system in a catchment must be weighed against the economic costs of sewage treatment and dispersal of household sewage for that system as well as cumulative pollution loads in that catchment Although ensuring that good treatment and dispersal of on site wastewaters is achieved the proximity of individual sewage systems to waterways and to adjacent systems also plays a part in the cumulative risk posed by that OSMS Systems close together and close to waterways pose more risks to the environment and public health because there is less opportunity for polishing of the effluent by natural processes on and in the soil BSC in their OSMS Design Guidelines and model provide incentives i e a smaller require
127. ny removal during treatment kg yr Dam soil P adsorption capacity kg ha m depth B buffer to water table default 0 5m T time to max soil adsorption limit default 50yrs Porop annual crop P uptake capacity kg ha Default in model is set at 10 kg ha year C1 4 Nitrogen Calculation As with the phosphorus calculation the model calculates the land application area size for nitrogen based on an annual nitrogen budget for the site Unlike the phosphorus cycle the nitrogen cycle has an additional gas phase that helps reduce the TN load to the terrestrial environment Again the model considers the treatment disposal process in a series of compartments or sub models which can be described as Source N loss during disposal re use area Household Treatment nitrogen output Soil Denitrification Crop Uptake Loss To Drainage Figure C3 Nitrogen balance sub model within OSMS Design Model Model assumptions for the nitrogen calculations are 1 20 of the TN arriving at the land application area will rapidly cycle through to the gaseous N phase and vent to the atmosphere 2 The default value for TN production is 4 2kg person yr 3 Plant N uptake is 200 kg yr unless otherwise justified Appendix C User Manual for OSMS Design Model Page C5 Byron Shire Council Doc 487794 The basic model function for the nitrogen calculation is described by the equation Area m U Nisaai EC X TEE Eqn 2 Where Area
128. ocated a minimum of 1200 millimeters above the top of the natural ground water table This depth may need to be increased to account for highly permeable soils low quality effluent and or potential sensitive environmental impacts 6 areas of high water table i e less than 1 2 m below ground surface groundwater recharge highly permeable soils and or containing rock outcrops shallow bedrock acid sulfate sodic or saline soils are considered major limitations to onsite effluent dispersal 7 treatment and application systems should be kept at least 100 m from Cattle Tick Dip Sites or other known contaminated sites unless detailed soil sampling confirms that there are no contaminated soils in the treatment or application areas 5 1 7 Run on and Upslope Seepage Any known run on or upslope seepage which might affect the application areas must be recorded on the site plan refer AS NZS1547 2000 The presence of flood debris and silt deposits may assist in identifying run on flowpaths If stormwater cannot be reliably controlled by the construction of a catch drain a diversionary swale or an interception trench above the dispersal field then an alternative location must be chosen 5 1 8 Flooding Potential The flooding potential of the site must be determined especially for low lying areas and flood plains All land application areas should be above the 1 in 20 year flood height and treatment systems should be above the 1 in 100 year floo
129. omponent of a soil sample by using a 2 mm sieve This is a difficult process when a soil is moist and heavy in which case a field estimate using abundance charts is acceptable A visual estimate of abundance should be recorded along with the size range of rock fragments and their corresponding amounts using Table 5a and 5b Table 5 Abundance a and Size b of Coarse fragments Source AS NZS1547 2000 of coarse Size of coarse A fragments EE fragments mm Very few lt 2 Fine gravel 2 6 Few 2 10 Medium gravel 6 20 Common 10 20 Coarse gravel 20 60 Many 20 50 Cobbles 60 200 Abundant 50 90 Stones 200 600 Profuse gt 90 Boulders gt 600 Design Guidelines for On Site Sewage Management for Single Households Page 14 Byron Shire Council Doc 491166 Where coarse fragments occupy more than 20 of soil volume and larger pores correspondingly accompany these coarse fragments the flow of water is not expected to be impeded Where coarse fragments occupy more than 20 of the soil volume but large pores accompanying the larger fragments are not present the water flow is expected to be impeded and the Soil Category should be increased by one class e g a Clay Loam should be classed as a Light Clay for permeability estimation purposes Where there are more than 20 cobbles stones and boulders this can impede surface preparation and excavation and contribute to trench collapse 5 2 6
130. on system Byron Council therefore recommends that effluent from the sullage tank be further filtered and or treated before land application e g in a reed bed or sandfilter The size of the application area required to safely disperse of greywater depends on effluent volumes and household inputs and may be calculated using Byron Shire Council s OSMS Design Model refer Appendix C The minimum allowable size for a greywater dispersal bed must be calculated based on the nutrient uptake and hydraulic capacity of the land application system but in no cases shall it be smaller than 10 m per person in the household This minimum figure is based on hydraulic dispersion capabilities of most soils and would only be considered appropriate for at least partial secondary treated greywater refer Section 6 3 6 2 3 Effluent Filters An effluent filter is a coarse screen filter that fits into the outlet of a primary treatment tank Effluent filters reduce Total Suspended Solids TSS carry over and thereby extend the operational life of land application components Effluent filters are required to be fitted on the outlets of both septic and greywater tanks Homeowners shall be made aware of the frequency and mode of cleaning before a particular filter is selected refer Appendix G Design Guidelines for On Site Sewage Management for Single Households Page 19 Byron Shire Council Doc 491166 6 3 SECONDARY amp PARTIAL SECONDARY TREATMENT For t
131. oroughly any fruit or vegetables which could have contacted the effluent Don t extract untreated groundwater for cooking and drinking Don t allow any foreign materials such as nappies sanitary napkins condoms and other hygiene products to enter the system Chemicals in cleaning agents disinfectants shampoos and bleaches etc can be detrimental to treatment systems minimise or avoid their use Vinegar lemon juice vegetable oil based soaps and hydrogen peroxide could be considered as alternatives Do not empty paint petrol pesticides medications or chemicals down sinks Disposable nappies sanitary napkins paper towels plastics etc block treatment systems Dispose of these separately Additional information should be added by system designer as appropriate G2 6 Problem solving All on site systems need to be regularly maintained in order to function well If particular problems are found such as gurgling or unusual toilets slow draining wastewaters unusual odours unusually noisy pumps or other components surcharging effluent from any treatment or land application systems or poor vegetation growth in irrigated areas ee e e e these symptoms should be investigated by your service provider as soon as possible Many systems include a light and or sound alarms to alert the homeowner of any overload problems If one of these alarms goes off the householder must contact the relevant service provider
132. ot necessarily reliant upon power or pumps and therefore economical to operate in the long term Details of reed bed design requirements are provided in Appendix A Sizing options for secondary and partial secondary quality effluents is incorporated into the OSMS Design Model Operation and maintenance requirements for sand filters are provided in Appendix G 6 4 TERTIARY TREATMENT In domestic on site sewage management tertiary treatment is generally taken to mean disinfection of secondary treated effluent but it may also include additional secondary treatment filtration and or nutrient removal 6 4 1 Disinfection There are a number of options for effective long term disinfection for on site systems Chlorination is commonly used with AWTS s Some systems use bromine UV light or ozone to disinfect For surface spray or dripper under mulch irrigation systems the effluent must be disinfected after partial secondary treatment Subsurface irrigation requires partial secondary or secondary treatment but does not require disinfection NSW Health regulations require that disinfection of AWTS effluent occurs in most cases even for sub surface applications Design Guidelines for On Site Sewage Management for Single Households Page 22 Byron Shire Council Doc 491166 6 5 OTHER CONSIDERATIONS 6 5 1 Maximisation of Effluent Take up by Plants Land application areas calculated by the OSMS Design Model or similar means should be conside
133. rd solution for all sites Each site and each owner have specific requirements that must be addressed The following step by step guide will assist designers and owners in selecting and designing the most suitable options for their specific sites 1 3 NSW HEALTH ACCREDITATION OF OSMS FACILITIES Under the provisions of Division 6 Clauses 42 and 43 Local Government Approvals Regulation 1999 a local council must not approve of the installation of certain sewage management facilities unless they have been accredited by the NSW Department of Health Details of which sewage management facilities are affected by this legislative requirement and the process for gaining accreditation are provided along with other relevant information on NSW Health s website at http Awww health nsw gov au public health ehb general wastewater wastewater html 1 4 MORE INFORMATION There exists in the literature a wealth of information regarding on site sewage management Those seeking further detail than is provided within this document are referred to the following for example Environment and Health Protection Guidelines On site Sewage Management for Single Households 1998 available from the NSW Department of Local Government This document can be downloaded from www dig nsw gov au Australian Standard AS NZS 1547 2000 On site domestic wastewater management Available from Standards Australia PO Box 1055 Strathfield NSW 2135 or www standardsaustral
134. re but higher maintenance and monitoring conditions will be required to ensure that the mulch remains in place over the drippers and that casual access by children vehicles and livestock is restricted by a vegetative border fence or similar device Disinfection of effluent is generally required Refer Appendix G for other maintenance requirements 7 6 SPECIAL COMPONENTS USED IN LAND APPLICATION AREAS Besides the components described above and in Appendix B there are a number of important auxiliary components which are generally found in land application systems 7 6 1 Indexing Valves Indexing valves allow for up to six 6 separate land application areas beds or irrigation areas to be used The indexing valve will apply a set volume of effluent to the first application area after Design Guidelines for On Site Sewage Management for Single Households Page 25 Byron Shire Council Doc 491166 which the pump turns off and the valve automatically switches to the next application area where the process is repeated 7 6 2 Dosing Siphons Gravity driven dosing siphons are becoming more popular in the North Coast region These are unpowered devices that ensure effluent reaches the treatment or dispersal system in a periodic slug rather than a constant dribble thus providing more even distribution and more successful treatment and or dispersal of effluent Siphons are generally located after the collection tank grey or blackwater
135. reated effluent because of the ability of the plants to reduce pollution loads while at the same time enhancing the beauty of the locality The subtropical climate allows a large range of plants to be selected for this purpose compared to other parts of NSW refer Appendix D Land application systems can get overloaded with effluent and fail over time and an alternate land application area must be designated and set aside for future use should the primary application field become less able to accept effluent or its contained nutrients over time It is recognised that some existing properties do not have sufficient room for an alternative application area In these cases it is important that a higher level of effluent treatment be performed and preferable to be able to alternate the available land application areas thereby allowing each area to rest in an unsaturated state for significant periods each day B1 Absorption Trenches Absorption trenches rely on infiltration of effluent into the ground beneath Historically this was the only wastewater dispersal method used in the region irrespective of the soil type Absorption trenches do not provide for substantial re use as the effluent is concentrated below the root zone forcing most of the water downwards to potentially pollute underlying groundwaters They are also prone to failure due to clogging and hydraulic overloading For these reason traditional absorption trenches are not generally
136. red minimum requirements only Council encourages all applications to maximise re use of effluent into the filtering matter of plants and any alternative applications that achieve a higher re use than is required to comply with these design Design Guidelines are encouraged Those wishing to distribute effluent in a manner that best serves their garden and still complies with Council and State guidelines are welcome to submit plans for consideration by Council that will better meet this objective 6 5 2 Phosphorus Removal Land application areas located on sandy soils may need suitable soils to be imported into the land application area to aid in phosphorus removal Filters specifically designed to remove phosphorus may be incorporated into secondary treatment devices e g through the use of media with a high phosphorus sorption capacity The media in such systems will need to be replaced once it becomes saturated with phosphorus 6 5 3 Wet Weather Storage The NSW guidelines E amp HPG 1998 highlight the desirability of not irrigating effluent during wet weather as this may lead to occasional surcharging and contamination of run off waters with effluent Byron Shire Council agrees with this sentiment but believes that for single domestic applications the expense difficulty and increased risks to householders of contacting the effluent often outweigh the potential health and environmental risks of effluent contaminated run off during very w
137. rflows If overflows occur it is important that effluent is not contacted by residents but also that the overflow is visible and cannot be readily ignored for sustained periods Council encourages the installation of appropriately sized emergency overflow trenches provided that inlets from the component are not sub surface connections 6 5 6 Pit or Pan Toilets Due to the risk these types of toilets pose to human health and the environment simple pit or pan toilets are now required to be upgraded to more suitable toilets such as composting toilets with greywater treatment Design Guidelines for On Site Sewage Management for Single Households Page 23 Byron Shire Council Doc 491166 7 CHOOSING ALAND APPLICATION SYSTEM Effluent quality plus site and soil specific parameters largely determine the appropriate land application system for any given situation but cost and maintenance requirements are also clearly relevant in making the necessary choices The strengths and weaknesses of various land application systems are summarised in Tables 4 2B1 and 4 2B2 of AS NZS1547 2000 whilst a brief description of each option is provided in the following sections Greater detail of each land application system may be found in Appendix B and maintenance requirements are provided in Appendix G The sizing of the land application area may be calculated using the OSMS Design Model as outlined in Appendix C Reserve application areas with equivalent
138. rmed using a sharp knife sickle or whipper snipper January after the spring summer growth flush and May prior to dormancy are probably the optimum harvest times from the perspective of both nutrient removal and aesthetics The reeds are cut back to approximately 20cm in height The cut material should be removed from the bed and can be used as mulch elsewhere During macrophyte establishment weeding of the bed may be necessary Weeds can be pulled out very easily from the wet gravel Strategic flooding may also be periodically used to drown out terrestrial weeds Because substrate blockage is the primary failure mode of reed beds steps should be taken to minimize carryover of solids from the primary treatment device The septic tank should have an effective outlet filter fitted This filter should be cleaned regularly sludge and scum levels checked and when necessary tank pumpout conducted Where blockage has already occurred lowering of the water level can sometimes lead to recovery Reed bed Operation amp Maintenance e The person nominated in the Approval to Operate is to check fluid levels are correct and that inlets outlets are clear of root blockages every three months Weeds should be removed regularly e A service contractor should perform a system check every twelve months e The reeds should be harvested at least once per year contractor or owner G3 1 6 Composting Toilets Composting toilets work by encouraging solid h
139. rms drains or gullies that might divert run off onto or around effluent application areas o buffers surrounding the effluent application areas Layout of land application area This may be either a detailed plan or if stated in the application a conceptual diagram with a detailed design to be provided and approved before installation commences Full specifications and engineering details of proposed Treatment System s Details of the chosen systems along with justification for the choice and proposed sizings of system components Where relevant calculations used in the design shall be submitted to allow Council to assess all individual components of the sewage management system including construction installation operation and maintenance Printout of all calculations and input parameters used to calculate land application area and OSMS component sizings f using Councils OSMS Design Model the input worksheet output Council Report worksheet and the Design Model worksheet must all be submitted with the application Justification must be provided if any non default values have been used as inputs to the model Completed site and soil assessment forms shall be appended Plans of management designed to be extracted from report and kept in a logical location for easy future reference by the resident home owner A pro forma for household OSMS management plans is provided as Appendix G Council recommends that this pro forma be us
140. s reason it is permissible to provide a conceptual plan of the application field clearly stating the size type and approximate layout of the proposed irrigation system with the Design Report If Council approves the proposed system a detailed irrigation design in accordance with the relevant Approved Drawing will need to be submitted for approval prior to application for a Permit to begin the installation Alternately the detailed irrigation design may be submitted with the Design Report to save processing time All detailed irrigation designs are to be produced by a person with suitable experience in irrigation design Irrigation designs submitted to Council are to include the information set out in the Irrigation Design Check List Appendix F Design Guidelines for On Site Sewage Management for Single Households Page 29 Byron Shire Council Doc 491166 Site Plans All reports are to include two site plans as follows 1 a small scale contoured location plan extending to surrounding areas and 2 alarger scaled plan showing the location of the following components o the proposed sewage treatment components o pegged out effluent application areas including soil analysis bore locations o water supply wells and bores o driveways buildings and facilities o environmentally sensitive areas including permanent or seasonal waterways o major landforms around the site including steep and flat areas built and natural bunds be
141. s to the relevant sections of the Design Guidelines are provided in Table 1 where appropriate A computer based model using MS Excel has also been developed by Byron Shire Council to assist in the design and sizing of effluent treatment and land application systems refer Appendix C Note that the requirements that must be met by installers of OSMS once an OSMS design has received Council approval are provided in Section 10 page 31 Design Guidelines for On Site Sewage Management for Single Households Page 4 Byron Shire Council Doc 491166 Table 1 Steps required in preparation of an OSMS design report for submission to Byron Shire Council Relevant section of Design Step Task Guidelines to refer to 1 Undertake desktop research Section 3 0 page 5 2 Identify wastewater sources and water utilising devices Section 4 0 page 6 Appendix and estimate hydraulic loads C OSMS Design Model 3 Conduct detailed site and soil assessment to identify Section 5 0 page 8 Appendix potential limitations of the site and soil for accepting B and H effluent 4 Identify suitable treatment and land application options Section 4 5 Appendices A amp B and consult with client to determine preferred options 5 Design treatment system Appendices A and C OSMS Design Model 6 Determine the most suitable method of land application Appendices B and C OSMS system and calculate the size of the land applica
142. s within 1 5m of the soil surface the depth to bedrock should be entered into LAA calculations e g in cell B14 in Byron OSMS Design Model and amelioration measures should be considered to compensate for the constraint refer Table 6 5 1 6 Buffer Distances Accurate distances to certain critical features must be recorded as described below Appropriate setback distances are determined by the E amp HP Guidelines 1998 or the Beavers and Gardner method described in their published paper Beavers and Gardner 1993 It is likely that there will be difficulties in obtaining the necessary parameters i e accurate estimations of soil permeability to use the Beavers and Gardner method however in which case the default setback distances set out below should be used Byron Council accepts that the following buffer distances cannot always be met Where it is necessary or for some reason highly desirable to reduce the one or more of the buffer requirements greater attention shall be paid to improving quality of the effluent or expanding the size of the land application area Refer Table 6 Where it is proposed to place the treatment system or land application area within the following buffer distances the designer must provide a written evaluation of the potential risks for the transfer of pathogens from the OSMS to residents or neighbours refer Section 4 2 2 and proposed amelioration measures to be taken to reduce health and environmental risks in
143. sign Guidelines System Management Plan Page G2 Byron Shire Council OSMS Design Guidelines Appendix G 487883 Holding tanks Pumps Filters Alarms light siren Other Land Application System Absorption trenches Mound system Evapotranspiration beds Sub surface irrigation Surface irrigation Other A detailed plan and technical details of the various components should be appended to this report G2 Advice for Home Owners G2 1 Background Information Wastewater may be blackwater toilet waste or greywater water from showers sinks kitchens and washing machines or a combination of both Greywater sullage can have a high percentage of the same pollutants as blackwater but composting toilets are strongly encouraged due to the overall reduction in water used and nutrients which need to be taken up Additional information to be added by system designer as appropriate G2 2 How does my OSMS work The components listed above collectively treat and disperse the household wastes within your property refer attached plan The following section provides a brief overview on how the components work together to achieve this An OSMS generally consists of three main parts the wastewater source treatment components and a land application area for the final reuse or disposal of the treated effluent These components are represented graphically in Figure
144. similar are to be complied with Certification of such activities shall be provided by the plumber installer and submitted to Council Final inspection will not be approved until such certification is submitted to Council Failure to obtain an inspection in accordance with an Approval by Council is an Offence under the Local Government Act 1993 Persons breaching this legislation are liable to prosecution or infringement notices which will result in a monetary penalty Variations Council expects systems to be installed in strict accordance with the plans which it has approved If it becomes necessary for any reason to substantially alter the design or configuration Design Guidelines for On Site Sewage Management for Single Households Page 31 Byron Shire Council Doc 491166 of the treatment and or land application systems a s96 for systems approved as part of the D A or s106 for systems approved under s68 of Local Government Act application will need to be sought and approved before proceeding with the amended installation Where the necessary amendments are of a very small or insubstantial nature check with Council if unsure it is permissible to install the altered system provided that a Works as Executed diagram is provided within two weeks of the installation The Works as Executed diagram must clearly show the size of all OSMS components and their position relative to major features e g house driveway and or waterways
145. sinks at all times and by tipping larger volumes of oils or fats into garden Insinkerators or similar types of in sink macerators should not be installed unless these have been specifically addressed and accounted for in the OSMS designs Where large volumes of oil or grease are likely to be flushed down sink a grease trap should be installed and regularly maintained Additional information to be added by system designer as appropriate Appendix G to Design Guidelines System Management Plan Page G4 Byron Shire Council OSMS Design Guidelines Appendix G 487883 G2 5 What should avoid Almost all sewage treatment systems use microorganisms to treat and break down the sewage components Regardless of the system type it is therefore vitally important that the health of the micro organisms that perform the treatment be protected Any materials or fluids which are toxic to animals e g bleaches disinfectants whiteners nappy soakers and spot removers fuels etc can be presumed to be toxic to microorganisms Many medicines e g antibiotics contraception pills can also have harmful effects on the microorganisms in the treatment system or the broader environment and should not be flushed into the household wastewater system Besides not placing poisons in your system the following should be avoided Don t let children or pets play on land application areas Don t water root vegetables with effluent and clean th
146. ss sand filter with anaerobic zones or by carefully recirculating between a third and a quarter of the sand filter effluent back into the primary treatment tank or 25 without the return Fully recirculating sand filters in which at least 75 of the treated effluent is recirculated back over the sand which are suitably sized and operating correctly can expect to reduce nitrogen by at least 40 These values are reflected as defaults in the Byron OSMS Design Model used to size treatment and dispersal systems in the shire refer Appendix C but system designers are encouraged to provide submissions based on other nitrogen reduction values if they can justify these values with independent monitoring results from installed systems Domestic sand filters which are available off the shelf by retail are required to accredited by NSW Health Two important aspects to understand about sand filter design is the type and character of media used and ensuring that effluent is evenly and intermittently spread to ensure that maximum contact with all the available sand in the filter is achieved Passive sand filter designs that dribble directly from the septic tank into the sand filter are not expected to achieve high levels of treatment due to the poor distribution of effluent over the filter surface and reduced contact opportunities with the bacteria laden sand grains Therefore intermittent loading using a dosing siphon or a pump is generally required for
147. stry as preferred and affordable approaches In domestic on site sewage management current best management practice generally includes partial secondary treatment and broadly dispersed application of effluent to soils in the root zone Biochemical Oxygen Demand BOD the amount of oxygen required for the biological decomposition of organic matter usually measured over a period of 5 days BODs Blackwater human excreta and water grossly contaminated with human excreta for example toilet wastewater Boulder a rock with middle dimension greater than 600mm Compost Toilet a treatment unit which breaks down faeces and organic material into a compost like material through the action of micro organisms and invertebrates See AS NZS1547 2000 Constructed wetland also known as Reed Beds these comprise a constructed basin in which water or effluent is kept at or near the surface of the gravel substrate The effluent is treated as it moves slowly through the root zone of densely planted water plants usually reeds Crop factor a value utilised in water balance modeling to estimate variations in evapotranspiration due to crop type seasonal conditions and age of crop Design Loading Rate the rate at which effluent is to be applied based on the Long Term Acceptance Rate LTAR see definition below reduced by a factor of safety Design Guidelines for On Site Sewage Management for Single Households Page 33 Byron Shire Council Doc 491
148. sts in the proposed dispersal area how deep the soil is and how the soil changes at depth You will also need to measure the distance the proposed dispersal area is from permanent or intermittent waterways and any nearby springs or bores In addition you will need to consider what type of system will be selected as a treatment option as well as which of the domestic water using facilities are to be connected to the treatment system Property size and potential locations for wastewater treatment and land application areas also need to be measured so that the options can be considered in the model This simplified application of the model is designed to provide guidance in estimating minimum land application area sizing for commonly occurring site characteristics The main benefit of the simplified model is that it allows the user to experiment with a range of water usage patterns in combination with various treatment and land application options to arrive at a site suitable sewage management system Example 1 The following example applies the model to a situation which might typically be encountered in Byron Shire A family of five wish to build a four bedroom home on their north facing one hectare 10 000m property located on rolling hills fifteen kilometres West of Byron Bay The owners will capture rain water as their preferred water supply but will supplement this with tanker deliveries All domestic water using facilities are to be connect
149. t However the household greywaters and the liquid wastes from the composting toilet will still need to be collected and treated in an appropriate manner The reduced flow rates are incorporated into Councils OSMS Design Model Greywater can be treated in conventional septic tanks AWTSs reed beds or in systems specifically designed and approved for greywater Leachate from the compost toilet must be directed to the greywater tank or its own designated trench This can actually help the biological process in the greywater tank by adding valuable bacteria If a reedbed is used the nutrients in the leachate help promote reed growth Leachate management must be included in any treatment design that involves the use of a compost toilet It is important to ensure that flies and rodents are excluded from the interior of the toilet Thus stainless steel fly wire should be placed over any exposed ventilation openings and the toilet lid kept closed when not in use It is also important to minimise the introduction of excessive moisture to the heap by hosing or cleaning Care and maintenance requirements for composting toilets are provided in Attachment G A6 Greywater Systems Greywater is the wastewater produced from sinks washing machines showers and dishwashers while blackwater is that produced from a flush toilet Currently there are no treatment systems approved by NSW Public Health solely for greywater treatment The basic greywater system expect
150. t flood levels in some areas and local information may need to be sought Design Guidelines for On Site Sewage Management for Single Households Page 5 Byron Shire Council Doc 491166 4 ESTIMATING WASTEWATER GENERATION 4 1 PREDICTED HYDRAULIC FLOW For existing dwellings fitted with a water meter an accurate estimate of household sewage volumes can be obtained by monitoring the meter readings over a number of weeks when little or no outside watering is occurring or examining water usage reported on previous water bills during wet periods For new houses or where no meter readings are available effluent generation rates should be based on the potential maximum number of people that may inhabit the dwelling at any one time In Byron Shire this is calculated on the basis of the number of bedrooms multiplied by 1 5 persons per bedroom unless there is information to suggest that more people will be or are living there in which case the higher number should be used Installing water efficient fittings and appliances in the household to minimise wastewater generation rates can achieve significant reductions in the size and cost of treatment and land application components of OSMS Installing composting toilets rather than flushing toilets can achieve the greatest single reduction In consultation with the home owner the OSMS designer is required to refer to AS1547 2000 to determine appropriate wastewater generation rates based on what th
151. te health and environmental risk until sufficient microorganisms are once again restored to adequately treat the effluent Furthermore AWTS s require regular quarterly maintenance to ensure that adequate disinfection via chlorination is maintained if this is required by their NSW Health Accreditation This is why Byron Shire Council will usually only approve sub surface irrigation as the land application method connected to an AWTS The sometimes high up front and quarterly monitoring and maintenance costs associated with AWTS must also be considered when choosing an AWTS Maintenance requirements for AWTSs are detailed in Appendix G Design Guidelines for On Site Sewage Management for Single Households Page 21 Byron Shire Council Doc 491166 6 3 2 Sand Filters Sand filters or derivations using other media are an alternative type of secondary treatment device popular in the Europe and North America Sand filters are generally of two types single pass and recirculating Sand filters work best when the effluent is spread in even pulsed doses over the top of the sand bed This can be achieved under gravity using a dosing siphon if sufficient static head fall is available or more commonly by electric pump Adequate primary treatment and good filtering must be maintained to prevent too much carry over of suspended solids and consequent clogging of the upper layers of sand media A disadvantage of some single pass sand filters is the
152. tect land application areas e A suitable service provider using the maintenance checklist provided as Appendix F as a guide must service all land application systems at least once per year e Most AWTS depending on their NSW Health accrediation must be maintained quarterly by a suitably qualified and experienced independent service provider and all pumped irrigation systems must be flushed at least once every three e Maintain stormwater diversion devices e g swales drains to ensure that stormwater does not run on to land application area e Do not drive over land application areas except with ride on mowers e Keep stock e g cattle and horses away from land application areas e The corners of each land application area should be clearly demarcated and casual access by children vehicles and livestock should be restricted This may be achieved by means of low fencing or preferably with low vegetative borders that don t greatly shade out the area e Keep grass short and trim the vegetation when necessary to let sunlight in promote plant uptake and remove nutrients from the land application area G3 2 1 Absorption Trenches Besides the above generic maintenance advice absorption trenches should be regularly checked to ensure that they are not surcharging G3 2 2 Mounds Raised effluent application systems such as Wisconsin Mounds are sometimes used where natural soils are extremely permeable and or underlying groundwat
153. ternatively AS 1547 2000 provides indicative permeabilities based on textural and structural soil characteristics refer Appendix 4 2 of AS1547 cited above 5 2 4 Colour Description The colour of a soil is often a good indicator of state of saturation of the soil in turn reflecting the oxygen availability in the soil For example red or brown colours generally indicate well aerated soils lying above the standing water table while grey or white soils are often found in saturated or periodically saturated soils A detailed colour description of the soil profile should therefore be conducted during the soil assessment The soils should be described in the moist condition by the following colours black white grey red brown orange yellow green or blue The classification can be modified as required by the words pale dark or mottled Transitional colours may be described as a combination of these colours e g red brown When a soil horizon has a predominant colour with mottles of another colour it is described in the form predominant colour mottled secondary colour e g grey mottled red brown Where two colours are present in roughly equal proportions the colour description is described in the form mottled first colour and second colour e g mottled brown and red brown 5 2 5 Assessment of Coarse Fragments Coarse fragments include hard rock material and nodules or segregations These may be separated from the fine earth c
154. tes R W and Middlebrooks E J 1995 Natural Systems for Waste Management and Treatment McGraw Hill New York United States Environmental Protection Agency 1999 Wastewater Technology Fact Sheet Intermittent Sand Filters EPA Office of Water Washington D C EPA 832 F 99 067 Design Guidelines for On Site Sewage Management for Single Households Page 37 Byron Shire Council OSMS Design Guidelines Appendix A 487879 Design Guidelines for On site Sewage Management for Single Households APPENDIX A OSMS Treatment Systems Byron Shire Council OSMS Design Guidelines Appendix A 487879 Appendix A Treatment Systems There are a number of different treatment systems available in the North Coast area and the performance of these can vary due to climatic conditions population characteristics loading cycles human dietary habits and influent quality Only the main options are discussed in the following sections but designers are encouraged to monitor and take advantage of innovative technologies as they emerge The following design constants are applicable to all treatment systems e Adequate access must be kept available to safely maintain the system e A means of monitoring the vital elements of each treatment component must be provided e If overflow occurs from any component the predicted overflow points must be visible and in as safe a position as possible to reduce or eliminate casual contact A1 Septic amp S
155. th it may sometimes be acceptable to use a discharge control trench in which the trench beneath the distribution pipe is deepened and filled with washed sand refer AS NZS1547 2000 for design details On other types of highly constrained site e g where only very small land application area is available it is sometimes appropriate to distribute effluent in micro trenches These micro trenches comprise narrow shallow gravel filled trenches in which sub surface irrigation pipes are installed The advantages of micro trenches is that by shallowly laying them along the contour and pumping the effluent into them they can distribute effluent reliably evenly and intermittently Assuming that stormwater is adequately diverted micro trenches provide a good opportunity for reuse by plants and only a low risk of effluent surcharging during wet periods 7 2 EVAPOTRANSPIRATION ABSORPTION ETA BEDS EvapoTranspiration ET and EvapoTranspiration Absorption ETA beds are wider and shallower than traditional absorption trenches thereby providing a much greater opportunity for uptake by plants and reduced dependence on infiltration and soil assimilation capacities to treat the effluent ET and ETA beds have a number of limitations discussed in some detail in Appendix B3 Due to these limitations and their relatively high expense ET and ETA beds are not encouraged in Byron Shire If they are required to be installed a great deal of care is
156. tic test is performed before the reeds are planted in which the installed liner is filled with water to a specific level and is checked again 24 hours later A4 3 2 Flexible Liners The use of flexible liner membranes is strongly discouraged in the Byron Shire due to the common failure to achieve a water tight seal during installation indications that the liner will not last 15 years as required under legislation and the potential to be easily penetrated by macrophyte rhizomes if not designed and installed correctly Pharagmites australis has a particularly penetrative rhizome and has been known to penetrate flexible plastic liners frequently and even to penetrate the seals of stainless steel liners A4 4 Substrate The choice of wetland substrate will depend on the type and quality of influent the desired quality of effluent and the need to minimise the risk of clogging Gravel of 10mm diameter is preferred but up to 20 mm diameter is acceptable As a rule media consisting of larger particles will have higher hydraulic conductivities and be less prone to clogging but smaller particles provides more treatment surfaces and is easier to spread It is essential to place larger stones rocks gt 50mm around the inlet and outlet pipes to allow for ease of checking for root intrusion However these coarser substrates inhibit plant growth and therefore should not be used throughout the entire reed bed A4 5 Macrophytes Various macrophytes hav
157. tion area Design Model 7 Measure and peg out proposed land application area Section 8 page 27 Compile a diagram showing layout of proposed land application area 8 Compile the above information in a detailed design report Section 8 page 27 including preparation of OSMS Management Plan for homeowners Appendix G 9 Submit 2 copies of the report to Council for approval Section 8 page 27 Once design has been approved requirements for Section 10 page 32 installation by licensed plumber are set out in Installers Requirements 3 DESKTOP RESEARCH Desktop research must be undertaken to determine the approval status of any existing systems Deposited Plan DP and Lot numbers or BSC Parcel Numbers when known flooding depths and frequency risk of disturbing acid sulphate soils geology and soils of the area see Table 4 using for example Soil Landscapes of the Lismore Ballina 1 100 000 Sheet by Morand 1994 and other references as necessary All designers are urged to come to the Byron Shire Council counter in Mullumbimby to get a copy of a selective GIS image of the subject property ask for OSM Layer small fee applies This will show the approximate buffer distances to waterways proximity to registered water bores and cattle tick dip sites and slopes greater than 10 Approximate flood levels are usually available but unfortunately Council s mapping is not accurate enough to confidently predic
158. tions Reports are to accurately indicate the distances of dry gullies watercourses or any other environmental features in relation to the land application area Should a proposed system need to be located within the relevant buffer distance Section 5 1 1 or should a site be determined to possess environmental limitations upfront acknowledgement of the limitation and explanation of how it is proposed for the limitation to be managed is to be reported e g by maximising the distance from waterways improving treatment such as with a reed bed sand filter AWTS etc or increasing the size of the proposed application area It is unacceptable for important relevant issues to be dealt with implicitly or to not be commented upon Owner s Acknowledgement Effluent management reports are to include a statement by the owner that they are aware of the type of system being nominated in the report and of the maintenance schedule required to be carried out for the nominated system Reports without acknowledgement by the owner that they understand what is being proposed and are willing to commit to the recommended maintenance schedule will be rejected Irrigation Design Reports Irrigation design is a specialised field Should subsurface irrigation be nominated as the proposed land application system it may be appropriate to have the detailed irrigation design performed by a specialist other than the one performing the soil and site evaluation For thi
159. ts Patterson 1998 An indication of the broad soil category of a site can be obtained from Soil Landscapes of the Lismore Ballina or Tweed 1 100 000 Sheet Morand 1994 However soil parameter values within any one soil type can be highly variable As part of the initial desk top study the soil unit from this Design Guidelines for On Site Sewage Management for Single Households Page 11 Byron Shire Council Doc 491166 text should be ascertained in order to identify ikely site and soil limitations as well as indicate likely phosphorous sorption rates Table 2 will assist in this process Table 2 Soil Landscapes in Byron Shire showing likely limitations for effluent dispersal and phosphorous sorption Sources Morand 1994 P sorption analyses by EAL Southern Cross University 1998 Soil Unit Code Broad Soil Type Likely limitations Morand Asterisk indicates comments from Morand Morand 1994 1994 1994 P sorption kg ha m Morand 1994 Bagotville Sandy Duplex Flood prone footslopes 8 000 Bangalow Bg Red Basaltic Steep shallow May need benching and or 10 000 SDI on slopes Billinudgel Bi Yellow and red Acidic hardsetting soils mod CEC 10 000 podzols Black Rock Br Sandy podzol Waterlogging high watertables low CEC 1 000 Coolamon Co Red Basaltic Dark Steep shallow stony soils mass movement 10 000 Basaltic Disputed Plain Dp Alluvial hi
160. ub surface irrigation SSI spray irrigation or surface irrigation under mulch systems submitted to Council for approval are to be designed by a person with suitable experience in irrigation design Byron Shire Council recommends that designers of pumped irrigation systems should be accredited by holding a Certified Irrigation Designer Agriculture Micro certificate Irrigation designs are to include all the information set out in the Irrigation Design Check List Appendix E Sub surface irrigation spray irrigation or surface irrigation under mulch designs are to be installed by a suitably qualified person with experience in irrigation installation All effluent dispersal by irrigation including subsurface surface drip or spray is to be maintained on a regular basis in accordance with their conditions of approval for the installation An Irrigation Maintenance Report refer Appendix F is to be submitted by the service provider to Council within 7 days of servicing the irrigation area B4 1 SUB SURFACE DRIP IRRIGATION SDI Sub surface drip irrigation SDI systems also commonly referred to as sub surface irrigation SSI are the preferred means of dispersing effluent in the Byron Shire due to their precise and even distribution capabilities Sub surface drip irrigation is particularly appropriate where there are site or soil limitations or limitations such as steep slopes or on heavy impermeable often termed puggy soils and can eve
161. ullage Greywater Tanks The septic tank used for single houses is a small anaerobic settlement and digestion plant which reduces suspended solids from the wastewater and breaks them down to smaller particles The resultant effluent is lower in settled solids but still high in biological oxygen demand BOD nutrients and pathogens Septic tank effluent requires further biological treatment before release to the environment Modern septic tanks have been greatly improved by the installation of at least one internal buffer to reduce solids carry over Figure A1 by ensuring that the tanks are large enough to provide sufficient opportunity for settlement of solids and making the tanks water tight Inspection Openings To pump out CES further treatment or land application Sludge Scum Figure A1 Cross section of a typical septic tank When the effluent from the house reaches the septic tank most solids settle to the bottom commonly termed sludge whilst most fats oils and greases float to form a crust at the top and the middle zone is occupied by effluent which has a chance to settle before overflowing to the secondary treatment system The addition of enzymes or other proprietary additives may sometimes have short term benefits in reducing smells and blockages but are not strongly encouraged because they can increase solids carry over and should not be relied on to maintain functionality of the tank On the other hand the
162. uman wastes faeces to compost in a chamber beneath the toilet pedestal The subtropical climate of Byron Shire is suitable for compost toilets all year round The process is biological and involves micro organisms digesting the faecal heap and gradually composting the material to humus The time taken to reduce the material to humus is variable and the operator of a compost toilet must recognise that the compost heap is a living thing and needs to be cultivated and protected There are texts available for those wishing to use a compost toilet and these should be read and understood so that the compost process is encouraged by the household activities Dry composting toilets require a carbon rich bulking agent such as wood shavings shredded leaves shredded paper or preferably a mixture of these which needs to be applied after each use of the toilet This bulking agent also covers the faecal material and aids in reducing any odours from the compost The toilets must be vented and some have mechanical ventilation to ensure good air flow around the compost heap After a period of time faecal and bulking material is decomposed into a friable humus like compost material which is removed from a door at the base of the toilet Operation amp Maintenance e After each visit add some carbonaceous bulking agent e g mixture of paper straw woodchips e Poke flatten the compost pile to reduce height if a large cone of material forms Appen
163. uncil Report worksheet and the Design Model worksheet must all be submitted with the application The model s input parameters Design Guidelines for On Site Sewage Management for Single Households Page 27 Byron Shire Council Doc 491166 should all be determined from the evaluation carried out by the designer for that specific application and should all be justified in the accompanying report The OSMS Design Model will not allow operation for Soil Category 6 Medium to Heavy Clays or dispersive or shrink swell soils To calculate the effluent dispersal area in this situation it will generally be necessary to provide secondary treatment of effluent and to ameliorate soil conditions if they are dispersive then to apply the computer model as though the site had a weakly structured Light Clay soil with DLR value of 5mm day OSMS designers must be aware that computers models will not do all the thinking for the them professional judgment must be used at all times For example a system designer needs to think whether the quality of the effluent is suitable for a given land application system regardless of the area which the model calculates to be suitable Design Guidelines for On Site Sewage Management for Single Households Page 28 Byron Shire Council Doc 491166 9 DETAILS REQUIRED IN OSMS DESIGN REPORTS Once all of the necessary investigations site soil assessments and design calculations have been completed the information m
164. used Step 13 Select SS from land application type list box Step 14 Click on the Calculate button If input correctly the model should return a required application area of 443 m Step 15 The print button at the bottom of the page allows the full list of parameters that have been entered into the model to be printed and submitted to Council as part of the on site system design Light clays moderately structured Ksat 0 06 0 12mjd Light clays weak structured or massive Ksat lt 0 06m c Med to heavy clays strong struct Ksat 0 06 0 5m c Med to heavy clays mod structured Ksat lt 0 06m Med to hvy clays weak struct or massive Ksat lt 0 06m Level bed with grass lt DISPERSIVE soil Modified Emerson Aggregate test Soil as in root zone Coarse Sand z Fine sand Sandy loams es Avail Water Capacity Loams Clay loams Silt 0 37 AWC of root zone 0 15 Clay light med heavy Land EE STEP 14 STEP 15 Calculate or Cntl Print Council Page l Figure 8 Steps 11 15 Design Model Unlike the previous example using the Designer Input Sheet the size of the land application area here is increased by the high water table which reduces the capacity of the soil to adsorb phosphorus In this example there are fewer options to decrease the land application Although a high level of treatment is being used in this case it does little to remove phosphorus The principal option in this case would be to
165. ushing they also reduce household water usage by as much as 30 Consequently the size and complexity of the treatment component of the OSMS can be significantly reduced as only greywater is generated by the household Nevertheless it should be noted that compost toilets still Design Guidelines for On Site Sewage Management for Single Households Page 18 Byron Shire Council Doc 491166 generate a small amount of leachate that will need to be directed to the greywater management system or a small trench Details regarding the design and functioning of composting toilets are provided in Appendix A5 Operation and Maintenance advice is provided in Appendix G All compost toilet installations shall be strictly in accordance with the requirements of the Local Government Act 1993 6 2 PRIMARY TREATMENT Primary treatment refers to the physical removal of solids and organic matter through settling and sedimentation Collection tanks i e septic and greywater tanks for raw effluent provide significant primary treatment through settlement and anaerobic digestion of organic solids by microbes Primary treatment results in an effluent that is lower in suspended solids and biochemical oxygen demand organic matter but does not significantly reduce nutrient levels The level of primary treatment depends on the residence time of the sewage in the tank which in turn depends on the size of the tank the volume occupied by scum and sludge layers and the
166. ust be compiled into a detailed OSMS Design Report Two 2 copies of the report to must be submitted to Council as part of the Application to Install or Alter a Sewage Management Facility The report will need to be submitted with a Section 68 form available from Byron Shire Council Assessment and inspection fees will be payable for new or previously unassessed systems but fee exemptions currently apply where an upgrade is being proposed to an existing approved OSMS without being tied to an upgrade or extension to the house The details required in all consultants OSMS reports supporting an application to Council are as follows Proposed system A summary of the proposed system components is to be presented in the report on or near the first page so that the type and size of system to be installed is clear to Council officers owners and installers Number of residents This is calculated to be the number of bedrooms times 1 5 unless the actual number of people residing in the dwelling is greater in which case the number of expected residents should be used refer Section 2 3 Site Specific Information Reports are to be specific succinct and with information relevant to the site under review Justification of the type and sizing of system nominated is to be clearly set out in the report Reports must state the date s that site inspections were conducted and who conducted them with qualifications if relevant Site Limita
167. utans 3 5m Bleeding Heart Trees Note that large trees should not be grown directly on land application areas and should be set back a minimum distance of their projected height to avoid shading of the land application area Acacia melanoxylon 15 20m Blackwood Acmena smithii 5 10m Lilly Pilly Archontophoenix cunninghamiana 10 15m Bangalow Palm Casuarina glauca 10 15m Swamp Oak Commersonia bartramia 5 10m Brown Kurrajong Glochidion sumatranum 5 10m Umbrella Cheese Tree Hibiscus tiliaceus 5 10m Cottonwood Hibiscus Livistona australis 15 20m Cabbage Palm Lophostemon suaveolens 5 10m Swamp Box Melaleuca quinquenervia 10 15m Broad leaved Paperbark Melicope elleryana 10 15m Pink Euodia Syzygium australe 5 10m Scrub Cherry Tristaniopsis laurina 10 15m Water Gum Waterhousea floribunda 5 10m Weeping Lilly Pilly Exotic grass species BSC does not particularly promote the use of exotic grasses However if these grasses are already on site then they can be utilised in the land application area Doc 486497 Appendix D to Design Guidelines Plants suitable for land application areas Page D3 Byron Shire Council OSMS Design Guidelines Appendix E Treatment Service Checklist 422469 APPENDIX E OSMS Treatment System Service Checklist On Site Sewage amp Wastewater Management Strategy E1 Byron Shire Council OSMS Design Guidelines Appendix E Treatment Service Checklist 422469 Appendix E1 OSMS Treatment Syst
168. ystem components C1 2 Hydraulic Calculation The model performs a daily soil water moisture calculation to provide a baseline for the soil s capacity to absorb the next day s water input The calculation is based on rainfall infiltration hydraulic load from the household crop evapotranspiration from grass in this case and deep percolation drainage Rainfall and Class A Pan Evaporation Data for the 21yr period to 2003 was accessed from the Alstonville Agricultural Research Station and is considered to be representative of rainfall patterns likely to occur in this region Soil texture and structure both assessed in the field determine the permeability of the soil Predicted soil percolation values have been taken from AS NZS 1547 2000 and applied in the model where soil type is identified and selected The required land application area for the hydraulic load is the land area in m which will accept the volume of applied effluent for 95 of the time i e the 95 percentile for the 21yr data base Of the 5 of days that fall outside the soil capacity to accept this volume of water effluent contaminated runoff might theoretically occur It is assumed however that during these unusually high rainfall periods when some daylighting of effluent might occur almost all of the runoff would consist of rain water and that actual contamination would be so low and diluted that the overall effects would be negligible C1 3 Phosphorus Calcul

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