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Annex J5 - Infiltration Worksheet user manual

1. Figure 3 5 Attenuation in Saturated Zone worksheet H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 29 Table 3 5 Summary of data requirements for Attenuation in Saturated Zone worksheet blue cells Effective porosity of the aquifer Dry Bulk density of the aquifer material Half life for degradation of substance Time since substance entered groundwater Contaminant specific value Ka which describes the partitioning of a substance between the aquifer matrix and surrounding water Soil water partition coefficients will typically be derived from laboratory column experiments or field data where comparison with a conservative tracer is possible If a substance is conservative for example it coefficient In fissured and dual porosity Soil water partition Kg should be set to zero Input parameter o Units Comment Distance to compliance X m The distance from the point source to the point at which compliance with an environmental standard is required Ow fraction aquifers the effective porosity may be assumed to be the fissure porosity ane cael See Section 5 0 does not sorb to aquifer materials the Kd value Fraction of organic carbon foc Expressed as a fraction between 0 and 1 Organic carbon partition Koc Contaminant specific value coefficient which describes the partitioning of a substance between organic matter and water H1 Annex J5 Infiltration Worksh
2. Attenuation factor drainage blanket AFy2 Attenuation factor unsaturated zone AF Attenuation factor saturated zone Cs Compliance value mg l for example water quality standard or MRV You should regard any discharge limit values that are calculated using the InfWS as provisional We may need to take additional information such as variability of leachate quality type of treatment process and assumptions in choice of parameter values into account in defining the discharge limit values that will be specified as part of the environmental permit H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 10 3 1 General The InfWS incorporates 10 worksheets which have the following functions Table 3 1 Function of worksheets Title of worksheet Function of worksheet Introduction Brief instructions entry of site details assessor details substance and environmental standard used and its origin to derive the compliance value for transfer to subsequent sheets Infiltration System Data entry for infiltration system including infiltration rate and area of drainage field Attenuation_unsatzone Data entry for calculating attenuation in the drainage layer and the unsaturated zone Data entry for calculating dilution factor and substance concentration in groundwater immediately down gradient of the drainage field Attenuation_satzone Data entry for calculating attenuation factor in the satura
3. Environment Le Agency How to comply with your environmental permit Additional guidance for Groundwater risk assessment for treated effluent discharges to infiltration systems Annex J5 Infiltration Worksheet User Manual v2 0 We are the Environment Agency It s our job to look after your environment and make it a better place for you and for future generations Your environment is the air you breathe the water you drink and the ground you walk on Working with business Government and society as a whole we are making your environment cleaner and healthier The Environment Agency Out there making your environment a better place Published by Environment Agency Horizon House Deanery Road Bristol BS1 5AH Tel 0117 934 4000 Email enquiries environment agency gov uk www environment agency gov uk Further copies of this report are f available from our publications Environment Agency catalogue http publications environment All rights reserved This document may be agency gov uk or our National Customer Contact Centre Tel 03708 reproduced with prior permission of 506506 the Environment Agency H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 2 Groundwater risk assessment for treated effluent discharges to infiltration systems 1 Annex J5 Infiltration Worksheet User Manual V2 0 c s ccccceceeeeeeessseeeseeeeesesesssneneeeess 1
4. H1 Environmental Risk Assessment Annex j groundwater Environment Agency 2013 Groundwater protection Principles and practice GP3 H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 43 rish Environment Protection Agency 2005 An investigation into the performance of subsoils and stratified sand filters for the treatment of wastewater from on site systems Final Report for project 2000 MS 15 M1 The Hydraulic Performance and Efficiencies of Different Subsoils and the Effectiveness of Stratified Sand Filters Environmental RTDI Programme 2000 2006 Xu M amp Eckstein Y 1995 Use of weighted least squares method in evaluating the relationship between dispersivity and field scale Groundwater 33 6 H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 44 Appendix A Guidance for assessing appropriate input parameters for the InfWS v2 0 Worksheet Introduction Infiltration System Attenuation Unsatzone Factor Section Information to be completed for each assessment Concentration of substance in discharge Type of Treatment Specify Discharge Q1 or Q2 Area of Drainage Field and Hydraulic Loading Drainage Layer Infiltration Rate Thickness of drainage field Water filled porosity Bulk density of drainage material Option to Select Degradation pull dow n Half Life for Degradation of Substance days Soil Water Partition Coef
5. AFu for the drainage layer or unsaturated zone can be calculated from AFu 1 exp a on 1 aan Equation 8 2a 2a where Vu retarded contaminant velocity through the drainage layer or unsaturated zone m vur Inf R Equation 9 a longitudinal dispersivity m 3 5 Dilution worksheet The Dilution worksheet Figure 3 4 allows users to e Calculate a dilution factor to account for dilution by groundwater flow below the drainage field Box 3 3 e Determine the concentration of the substance in groundwater immediately down gradient of the drainage field and e calculate a provisional discharge limit value This limit may be superseded if attenuation in the saturated zone is taken into account Section 3 6 Project information data for example site and substance details and unsaturated zone attenuation factor are automatically transferred to this worksheet H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 23 Figure 3 4 Dilution worksheet Dilution Substance Compliance value or environmental standard Source concentration Concentration at base of unsaturated zone Input Parameters Standard entry Infiltration Area of drainage field Entry for groundwater flow below site Length of drainage field in direction of groundwater flow Saturated aquifer thickness Hydraulic Conductivity of aquifer in which dilution occurs Hydraulic gradient of water table Width of drainage
6. Fromintroduction sheet Contaminant Compliance value or environmental standare CT Concentration of substance in substance in discharge entering infiltration system Ce mgA Frominfiltraton sheet Input Parameters Variable Value Unit Source of parameter value Drainage Layer Infiltraton rate Inf md Frominfitraton sheet Thickness ofdrainage laye S1 m Water filled porosity 6 fraction Bulk density p g cm Calculated dispersivity calculated Option to select degradatio days Halflife for degradation of substance calculated very low value set if no days y degradation Calculated decay rate A PEO Seep a en ase eee ee a no EES Soil water partition coefficient used in assessmen Kd Retardation factor Rfut for organic chemicals ee a 28 Unretardedtraveltime no dispersion tut d Unretarded traveltime with dispersion tut d Retarded traveltime with dispersion t1 d Attenuation factor AFut Unsaturated Zone Thickness ofunsaturated zone below drainage fek S2 m Water filled porosity 62 fraction Bulk density of unsaturated zone p2 g cm Calculated dispersivity calculated Option to select degradatio Halflife for degradation of substance calculated very low value set if no days degradation Calculated decay rate 12 fraction Fraction of rapid fow through unsaturated zone ARO TRE O een ent A aa cae Entry if specify patton coefficient option perep a
7. Infiltration Worksheet user manual V2 0 c ccccesesseesceceeeeeeseeessenaneeeeeeeeseesesscaeseeseeeenseeeeanes 3 Obtaining and installing the INfWS sisccisccsacsssccciavevesiacviscsacniiscsntiisicesacednesaanteausdavsuvedacbascecasmenvisnss 4 RO SOV SPV NC Warina oa idasevanecaetecc sicutestacsveuseestaaiisecauectezivesttaeni daavtzaanes 5 2 0 The risk assessment approach and the site conceptual model ccssssseeeceteeeeees 8 2 1 Discharge limit val s sccsstecsisesinacsiicssknedvansnandanuarevansnncessasndvennsunsexdnsnnecssseunveveaninectucewixenterdeen 9 3 0 Using the individual worksheets ssaassunnnuunnuunnnunnnnnnnnnnnnnunnnnunnnunnnunnnnnnnnnnnnnunnnnnn ennnen nnna 11 3 1 eee cre eee errr a a a erm pe rte 11 3 2 INCTFOCUCTION WONKSIMGCE weit seiesssisteves i sxvresclisectetiaveds auasccbeveaeeti ts tase tectel aa a 12 3 3 Infiltration System WOPKSS CE aiisiscinssiscsnsssisvercsssstcssicesaieajecsncssaceansscessanstesaasectaveesiaganennete 13 3 4 Attenuation in Unsaturated Zone wWorksShee t cccssseeeeseseeeeeeeeseseeeeeseseeeseeseeeeeeeneees 18 3 5 Dilution WOMSNGGE oo 050s cccssescecceesccceevscecescececeseendaseadedcdenseaesesevstlacsscededeseuse saceceades sesndedease 23 3 6 Attenuation in the Saturated Zone worksheet cccssecccessseeeeeseesseeeeeeseeeeeeeeeeeensesesees 27 3 7 ACU ae Oh parame CON Seta gtt cicero ect nt raa i ri eae 28 3 8 Summary calculations WOMseet wissicssisicssse
8. and dilution Cow Ce AF uz AFuz DF Equation 2 iii Down gradient borehole attenuation in unsaturated and saturated zone and dilution non hazardous pollutants only Cacp Ce AFur AFu2 AFs DF Equation 3 where Cacp Concentration at down gradient compliance point mg l Concentration should be below compliance value Cow Concentration immediately down gradient of drainage field point mg l Cwm Concentration at base of unsaturated zone mg l Ce Concentration of substance in treated effluent discharge mg l AF Attenuation factor drainage blanket AF y2 Attenuation factor unsaturated zone DF Dilution factor AF Attenuation factor saturated zone H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 9 Box 2 2 Discharge limit values Discharge limit values DCL can be calculated as follows i Attenuation in drainage layer and unsaturated zone only DCL AFy AFy2 Ce Equation 4 ii Attenuation in unsaturated zone and dilution DCL DF DCL Equation 5 iii Attenuation in unsaturated and saturated zone and dilution non hazardous pollutants only DCL3 AF DCL Equation 6 Where DCL 3 Discharge limit value these will vary depending on whether compliance point is DCL base of unsaturated zone DCLz groundwater immediately down gradient of drainage field DCL groundwater down gradient of drainage field DF Dilution factor AF
9. been corrected This may have resulted in minor errors Obtaining and installing the InfWS You can download the InfWS version 2 0 from the Horizontal guidance environmental permitting on the gov uk website We have prepared and tested the InfWS in Microsoft Excel 2002 on the Microsoft 95 2000 XP operating systems The file comprises about 570 KB and should not require any significant additional computing capability beyond that needed to run Microsoft Excel 2002 We recommend that a blank copy is saved as a master file and that each simulation is saved as a distinct file In order to enable the InfWS a number of capabilities are required in Microsoft Excel 2002 that may not automatically be set The InfWS calculates error functions and complimentary error functions Before use you will need to add these capabilities by clicking the following from the pull down Tools menu Tools gt Add ins gt Analysis ToolPak and Analysis ToolPak VBA You must also Enable Macros when prompted to do so lf you are working in Microsoft Excel 2007 you will need to add these capabilities by clicking the Office Button and then the following from the pull down Tools menu Excel Options Add Ins gt Analysis ToolPak and Analysis ToolPak VB A 1 Irish Environment Protection Agency 2005 An investigation into the performance of subsoils and stratified sand filters for the treatment of wastewater from on site systems Final Report for
10. field perpendicular to groundwater flow Background concentration of substance in groundwater up gradient of site Define mixing zone depth by specifying or calculating depth using pull down list Enter mixing zone thickness Calculated mixing zone thickness Groundwater flow mixing zone below drainage field Dilution factor and discharge consent limit Cr Ce Cm Variable Inf Ammonium From introduction sheet 3 90E 01 mg l From introduction sheet 6 00E 01 mg l From infiltration sheet 1 64E 01 mg l From atten_unsatzone sheet Value Unit 7 20E 02 mid 1 25E 02 m 1 25E 01 m 2 00E 01 m 5 00E 00 m d fraction 1 00E 01 m 0 00E 00 mg l Calculate 0 00E 00 8 57E 00 Source of parameter value From infiltration sheet From infiltration sheet m Dilution Factor Unsaturated zone attenuation factor 1 95E 00 3 65E 00 From infiltration sheet Concentration in groundwater below drainage field Discharge limit value 8 41E 00 or 2 78E 00 The worksheet provides the following option brown cells Mixing Zone thickness Two options are provided 1 Specify the thickness of the mixing zone 2 Calculate thickness of the mixing zone see Box 3 3 A summary of the data requirements blue cells for this worksheet is given in Table 3 4 Depending on the options selected the worksheet will automatically grey out cells for which data entry is not required The Dil
11. of assessment and identifying run number are automatically transferred to each of the subsequent data entry sheets These details cannot be amended H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 12 within the subsequent worksheets and can only be modified by changing the entry on the Introduction worksheet The Introduction worksheet also includes brief instructions on the use of the worksheet and a reminder that Microsoft Excel 2002 Tools must be enabled to allow it to calculate error functions and complimentary error functions The worksheet will not calculate attenuation factors unless Microsoft Excel is set up to calculate these mathematical functions It is necessary to undertake a separate simulation for each substance in the treated effluent You can find guidance on selecting an appropriate environmental standard which are typically based on background water quality Minimum Reporting Values MRVs drinking water standards DWS or environmental quality standards EQS in Environment Agency 2011a and 2011b See also Box 1 1 Figure 3 1 Data entry required on Infiltration Introduction Worksheet Details to be completed for each assessment Site Name Enter site name Site Address Enter site address Completed by Enter user name Date Enter date Version X XX Substance Chemical Environmental Standard C 0 mg l Origin of C Specify basis for standard e g MRV EQS DWS 3 3 Inf
12. review of text layout and references H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 2 Infiltration Worksheet user manual v2 0 We have prepared this user manual to assist users of our Infiltration Worksheet v2 0 InfWS This document describes the functionality of the InfWS and gives guidance on its use including some simple tips for using and interpreting the results The InfWS provides a means of carrying out some of the calculations behind the framework on Annex J4 Groundwater risk assessment for treated effluent discharges to infiltration systems Environment Agency 2011a which forms a technical annex to our H1 Environmental Risk Assessment Annex J groundwater Environment Agency 201 1b More general information on our approach to risk assessment and the underlying regulatory context and our position are set out in the following documents e Groundwater Protection Principles and practice GP3 Environment Agency 2013 or as updated e Guidelines for environmental risk assessment and management The Stationery Office DETR et al 2000 We strongly recommended that you read and become familiar with the relevant sections of these documents before using the InfWS We have developed the InfWS to help determine the risk to groundwater from discharges of treated sewage effluent via infiltration systems such as a drainage field designed to British Standards and it should only be used in this conte
13. some sites the model results may be insensitive to these changes for example where there is a thin unsaturated zone or low groundwater flow rates and other factors may need to be considered for example relocating drainage field reviewing distance to compliance point increasing the thickness of drainage layer It should be noted that in some cases increasing L may reduce the influence of lateral dispersion on the model results and may lead to the model calculating lower permit limits which can be counter intuitive In these cases the sensitivity of the model to dispersion should be investigated including the choice of the Xu and Eckstein option or dispersivity based on pathway length Distance to the compliance point In some cases the analysis may indicate that changing the distance by 10 m may result in an acceptable concentration at the compliance point and therefore the current location may be reasonable Hydraulic conductivity This parameter will influence the dilution and attenuation factors in the saturated zone Site specific data are unlikely to be available and sensitivity analysis will be help to establish whether this is a key input parameter Effluent concentration This may help to establish whether additional treatment should be considered Dispersion co efficient For small drainage fields the model results can be sensitive to lateral and vertical dispersivity Therefore the influence of changing these parameters should be examin
14. 1 where A drainage layer or unsaturated zone decay constant d H Half life for degradation of substance d Vertical dispersivity in the drainage layer and unsaturated zone is calculated from 0 1 S Equation 2 S thickness of drainage layer S4 or unsaturated zone S2 below the drainage field m Soil water partition coefficient Kd is calculated for non polar organics from K Gen en Equation 3 where Koc Organic carbon partition coefficient l kg foc fraction of organic carbon Box 3 2 continued Retardation Factor in the drainage layer or unsaturated zone Rfu is calculated from Rfu 1 Kd p 0 Equation 4 where H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 22 6 water filled porosity of the drainage layer or unsaturated zone 2 fraction p dry bulk density of the drainage layer p or unsaturated zone p g cm The unretarded travel time tu through the drainage layer or unsaturated zone is calculated from tu S 0 Inf Equation 5 where Inf Infiltration rate through the infiltration system m d The retarded travel time tr through the drainage layer or unsaturated zone is calculated from tr tu Rfu Equation 6 The above calculation for unretarded travel times ignores dispersion if dispersion is taken into account the travel time is calculated from tu S a 6 Inf Equation 7 An attenuation factor
15. 2 0 7 2 0 The risk assessment approach and the site conceptual model The tools selected to model a site should be appropriate to the conceptual model and the quality of the available data Guidance on these issues is provided in e Guide to good practice for the development of conceptual models and the selection and application of mathematical models of contaminant transport processes in the subsurface National Groundwater and Contaminated Land Centre report NC 99 38 2 Solihull Environment Agency 2001a e Benchmarking and guidance on the comparison of selected groundwater risk assessment models National Groundwater and Contaminated Land Centre report NC 00 14 Solihull Environment Agency 2001b You should only employ the InfWS where a robust conceptual model has been developed and you are satisfied that the calculations performed are relevant to the processes described within that conceptual model The development of a robust conceptual model is perhaps the most important aspect in the process of successfully estimating and evaluating environmental risks The use of any mathematical modelling tool without first developing a robust conceptual model is likely to result in meaningless output and poor decision making The conceptual model should be supported by valid data Good quality site specific data is always preferred If you use generic data it should be reliable and relevant to the site You should document the provenance
16. DF would be expected to be in the range 1 to 2 if higher values are calculated then you should check the thickness of the mixing zone and the hydraulic conductivity to see if they are reasonable Dilution factors of greater than 10 should be treated with caution Attenuation Factor AFu drainage blanket values in range 1 to 5 are reasonable higher values indicate degradation rates may be too rapid and input values should be checked Attenuation factor AFu unsaturated zone values in range 1 to 3 are reasonable higher values indicate degradation rates may be too rapid and input values should be checked although may be reasonable if there is a thick unsaturated zone Attenuation factor AFs saturated zone values in range 1 to 3 are reasonable higher values indicate degradation rates may be too rapid and input values should be checked Higher values may be associated with higher porosity aquifers and or where distances to the compliance point of greater than 100m have been used Have conservative attenuation rates been used particularly for the unsaturated and saturated zone Half lives of less than 2 years should be treated with caution if justification is not provided half lives of 2 to 5 are likely to be reasonable and half lives of greater than 5 years are likely to be precautionary Dispersion co efficients for intergranular aquifers the Xu and Eckstein option is recommended for fractured aquifers the 10 option is recommended For sm
17. Infiltration Worksheet user manual December 2014 version 2 0 33 Figure 3 6 Calculated concentrations in the Attenuation in the Saturated Zone worksheet 1 0E 01 9 0E 00 8 0E 00 7 0E 00 6 0E 00 5 0E 00 4 0E 00 Concentration mg l 2 m 2 0E 00 1 0E 00 0 0E 00 30 Distance m 3 8 Summary calculations worksheet The Summary worksheet Figure 3 7 requires no input as it presents data from previous worksheets and provides Calculated concentrations for distance concentration graph From calculation sheet Distance m 0 2 5 5 0 7 5 10 0 12 5 15 0 17 5 20 0 22 5 25 0 27 5 30 0 Concentration mg l 7 7E 00 7 48E 00 7 28E 00 7 09E 00 6 90E 00 6 72E 00 6 54E 00 6 37E 00 6 20E 00 6 03E 00 5 88E 00 5 72E 00 5 57E 00 5 42E 00 5 28E 00 5 14E 00 5 00E 00 4 87E 00 4 74E 00 4 62E 00 4 49E 00 e Asummary of compliance point data dilution and attenuation factors e Calculated substance concentration at different points along the pathway base of unsaturated zone groundwater immediately down gradient of drainage field and groundwater down gradient of the drainage field e Provisional discharge limit values for different points along the pathway The Summary worksheet also includes a chart that summarises calculated concentrations between the source and the down gradient compliance point H1 Annex J5 Infiltration Worksheet user manual December 2014 ver
18. all drainage fields then lateral dispersion may be significant and in this case sensitivity testing is recommended See Section 6 Predicted concentrations at the compliance point should be compared with the target concentration as this may help to establish whether the discharge represents a significant risk or that further analysis would help to ascertain whether simple modifications to the design or location if the drainage field may reduce the risk to an acceptable level For degradation the option Degradation occurs sorbed and dissolved phases should only be used where there is field evidence to support the degradation rates used Where there is limited or no evidence no attenuation should be assumed See Appendix A for further advice on the selection of appropriate input values H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 40 6 0 Sensitivity analysis The InfWS uses a deterministic approach in the calculation of contaminant concentration and discharge limit values they assign a single value for each parameter which implies a high degree of confidence in that value In practice there will be uncertainty Sensitivity analysis is therefore recommended as part of the risk assessment process especially where there is not a high degree of confidence in the single value assigned for each parameter It is also useful in cases where the initial assessment indicates that the proposed permit limit for a su
19. and relevance of all data included in an assessment using the InfWS and include this in any report s submitted to us for consideration The InfWS should only be used when adequate site specific data have been obtained For further guidance on sources of information and which site specific data are required the reader should refer to Environment Agency 2011a and 201 1b The following guidance on reviewing assessments may also be of use in preparing reports for submission as part of any application e Guidance on the assessment and interrogation of subsurface analytical contaminant fate and transport models National Groundwater and Contaminated Land Centre report NC 99 38 1 Solihull Environment Agency 2001c H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 8 2 1 Discharge limit values Box 2 1 contains a summary of the basic calculations to determine the concentration of a substance at different points along the contaminant pathway Figure 1 1 Box 2 2 illustrates how the discharge limit values are derived Box 2 1 Summary calculations for determining the concentration at different compliance points Concentration at compliance point The concentrations of substances at different points along the pathway can be calculated as follows i Water table attenuation in unsaturated zone only Cwt Ce AFy AF y2 Equation 1 ii Borehole adjacent to infiltration system attenuation in unsaturated zone
20. ane chemicals option Soil water partition coefficient used in assessmen Kd2 Retardation factor Rfu2 S O Ikg Specified value 73 Unretardedtraveltime no dispersion tu2 d Unretarded tavel me with dispersion tu2 d Retarded traveltime with dispersion tr d Attenuation factor AFu2 Total unretarded travel time tu tu2 d Totalretarded travel time tr tr2 d Attenuation factor and discharge consent limit H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 20 ASummary of data requirements for the Attenuation in the Unsaturated Zone worksheet is provided in Table 3 3 Table 3 3 Summary of data requirements for the Attenuation in the Unsaturated Zone worksheet blue cells Drainage layer thickness S S gt m Essential to have site Must be and unsaturated zone specific measurement input thickness below the drainage field Water filled porosity of the Ow fraction Expressed as a fraction Must be drainage layer and the Owe between 0 and the total input unsaturated zone porosity value The water filled porosity value can be derived from water or moisture content measurement and density measurements Dry bulk density of Pu p2 g cm Must be drainage layer and input unsaturated zone material Half life for degradation of ti days See Section 5 0 Separate Dependent substance entry for drainage layer and on option unsaturated zone selected Percent rapid flow
21. ated Zone worksheets but not the effective porosity as used in the Attenuation in the Saturated Zone worksheet H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 37 The water filled porosity is calculated from Ow Or Ga Equation 1 Equation 2 Equation 3 Equation 4 Equation 5 6 water filled porosity fraction 0a air filled porosity fraction 6 total porosity fraction p dry bulk density of unsaturated zone g cm d particle density g cm MC moisture content weight S initial saturation Vr void ratio fraction It is important to note that these equations cannot be used to calculate the effective porosities used for the saturated zone attenuation assessment worksheet H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 38 The rate of degradation used for the unsaturated and saturated zone is likely to have a significant influence on calculated concentrations in groundwater and calculated discharge limit values Guidance on the selection of degradation rates is given in Environment Agency 2011b and additional information on transformation rates for ammonium is given in Environment Agency 2003 Contaminant decay is modelled as a first order reaction and degradation is defined by a half life expressed in days Decay rates should be based on field observation of contaminant destruction in groundwater or on conservative li
22. bstance is lower than its concentration in the treated effluent Such testing may help to inform whether further data collection is warranted the site should be relocated or the design modified Understanding how the magnitude of risks varies with changes in input parameter values is essential to understanding the certainty that can be placed on any prediction By varying selected input parameters in turn and observing the effect on the calculated concentrations you can determine which parameters have the greatest effect on the results If you then consider the likely range of values that apply to those parameters you can assess whether more data is needed to reduce uncertainty in the final result The alternative is to adopt conservative values for the sensitive parameters and accept that this may result in higher calculated discharge limit values Whichever approach is taken you should ensure that your assumptions are sufficiently protective of the environment Another common means of taking account of parameter variability is the use of probabilistic methods such as Monte Carlo analysis This InfWS is password protected and this may prevent the use of common commercial tools such as Crystal Ball and Risk to undertake Monte Carlo analysis If Monte Carlo analysis is required it is recommended that an alternative assessment tool such as ConSim Environment Agency 2004 is used Further guidance on assigning values to uncertain paramet
23. cient 1 00E 00 I kg Retardation factor of pollutant Groundwater flow velocity 1 16E 05 m s 1 00E 00 3 65E 02 m year Time for groundwater to reach receptor t GW 8 64E 06 seconds 1 00E 02 2 74E 01 years Rate of groundwater flow through aquifer Q 2 89E 03 m s 2 50E 02 9 13E 04 m year Contaminant flow velocity v contam 6 09E 07 m s 5 26E 02 1 92E 01_ m year Time for contaminant to reach receptor t contam 1 64E 08 seconds 1 90E 03 5 21E 00 years 4 2 Ammonium Conversion worksheet This Ammonium Conversion worksheet allows conversion between different laboratory analyses of ammonium The ammonium ion NH is typically the dominant ion at neutral pH However in more alkaline water the ammonia NH3 ion becomes increasingly dominant Laboratories may report the analysis for ammonium as NH or as N NH N In some cases the laboratory may have reported the result as Total ammonia as NH3 or as Total ammonia as N Total ammonia is likely to include ammonium NH and ammonia NHs In this case NH may be converted to NHs 4 3 Porosity Calculator worksheet Water filled porosities can be difficult parameters to measure directly at a site area but can be estimated from soil bulk density wet or dry particle density and moisture content The calculations presented in the Porosity Calculator worksheet Box 4 1 are suitable for inclusion within the Attenuation in the Unsatur
24. e selected to allow the assessor to select a predefined option Yellow cells should be used to record the origin or source of any data used in the worksheet Although failure to populate the Source of parameter value cells with appropriate text will not affect the spreadsheet calculations it is good practice to complete this task We will expect submitted reports to include these details Grey cells contain the results of each simulation reen cells contain information derived trom anotner part of the worksheet If you move the cursor over the red triangles at the corner of certain cells further information is revealed on the data required or equations solved Please also refer to Figure 3 2 3 2 Introduction worksheet When starting a new assessment you must complete details on the Introduction worksheet first Figure 3 1 This worksheet is displayed for all assessment options Data required in blue boxes on the Introduction worksheet include name and address of the site being assessed name of assessor date that assessment was completed and run version number name of substance environmental standard used to derive the compliance value and basis for environmental standard for example EQS DWS MRV background quality You must complete all blue cells on the Introduction worksheet before moving onto any other worksheets Data entered for the substance name environmental standard site name assessor s name date
25. e the Area of the Drainage Field depending on what option is selected H1 Annex J5 Infiltration Worksheet user manual 15 December 2014 version 2 0 Box 3 1 Standard equations for the Infiltration System worksheet The hydraulic loading or infiltration rate Inf is calculated from Inf Equation 1 where Inf Infiltration rate through the infiltration system m d Q discharge rate to drainage field m d A area of drainage field m see below Note The infiltration rate nf should not exceed the maximum infiltration rate from BS 6297 2007 A1 2008 This would indicate re design of the drainage field was necessary For some infiltration systems the design may include for storage to deal with peak flows in these cases the infiltration rate should be set as the maximum infiltration rate The discharge rate Q is calculated as follows Q pW x 1 000 m day to litres Equation 2 where Q discharge rate to drainage field m d p number of people served by the septic tank or package treatment plant W water use per person litres person day The area of a drainage field A for domestic premises is calculated from BS 6297 2007 A1 2008 A 0 25 p Vp for septic tanks Equation 3 A 0 20 p Vp for package treatment plants Equation 4 where A area of drainage field m p number of people served by the septic tank or package treatment plant V percolation rate determined from perc
26. ed This can be undertaken by noting the values calculated using the Xu amp Eckstein or 10 option and then entering these using the user specified option and then modifying e g 20 as part of the sensitivity analyses 7 0 Assessment of results In summary the factors that should be examined in carrying the risk assessment and which will influence our decision to reject or accept the application are Predicted concentration at the compliance point Input parameters and calculated factors for example DF AF and whether these are reasonable Results of sensitivity testing and whether changes to the design and or location would result in a reduction in risk The InfWS can be used through the use of scoping calculations and sensitivity analysis to identify how the proposed discharge could be modified to result in an acceptable discharge for example treatment to reduce the concentrations of substances increasing the area and thickness of the drainage layer or relocating the discharge to an area with a greater unsaturated zone thickness H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 42 References BS 6297 2007 A1 2008 Code of practice for the design and installation of drainage fields for use in wastewater treatment British Water 2014 Flows and Loads 4 DETR Environment Agency and Institute for Environment and Health 2000 Guidelines for environmental risk assessment and management The Stati
27. eet user manual 30 December 2014 version 2 0 Must be input Must be input Must be input Dependent on option selected Dependent on option selected Dependent on option selected inpatparameter Unie Comment Longitudinal transverse and vertical dispersivity aa az H1 Annex J5 Infiltration Worksheet user manual 31 December 2014 version 2 0 Values for dispersivity Dependent may be obtained from on option tracer testing or selected experience of local hydrogeological conditions Acheck should be undertaken to ensure that the modelled effects of vertical dispersion are not so great as to simulate a plume that extends beyond the base of the aquifer The worksheet will post a warning if this occurs Dispersed plume thickness exceeds aquifer thickness Reduce vertical dispersivity In these cases the value for vertical dispersivity should be reduced This can only be achieved under the option to enter dispersivity values Box 3 4 gives an overview of the equations used in the Attenuation in the Saturated Zone worksheet Box 3 4 Standard equations for Attenuation in Saturated Zone worksheet Decay rate A is calculated from A 1n 2 H Equation 1 where A unsaturated zone decay constant d H t half life days Soil water partition coefficient Kd is calculated from Ki Koad where Koc Organic carbon partition coefficient l kg foc fraction of
28. ength of drainage field in direction of groundwater flow Hydraulic conductivity of aquifer in which dilution occurs Width of drainage field perpendicular to groundwater flow Background concentration of substance in groundwater up hydraulic gradient of the site Mixing zone thickness of saturated aquifer below drainage field H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 Saturated aquifer thickness ee Hydraulic gradient of water fraction table 26 See comment on width of drainage field Must be input Must be input Must be input Must be input The worksheet automatically Must be multiplies L Wd and compares this with the area of the drainage field If they are the same the worksheet flags this w L does not equal area A of drainage field check parameters used This may be OK if drainage field is at angle to flow direction and no change in input parameters may be necessary The thickness of the mixing zone cannot exceed the saturated thickness of the aquifer If a value greater than the saturated aquifer thickness is entered the worksheet posts a warning that mixing zone exceeds saturated thickness Generally the full thickness of the aquifer will not be available for mixing of contaminants and a lesser thickness may be derived from evidence of high permeability zones from borehole logs annual water table fluctuation from input D
29. ependent on option selected hydrographs or local experience Many UK aquifers are layered systems with significant vertical heterogeneity that limits the potential for vertical mixing 3 6 Attenuation in the Saturated Zone worksheet The Attenuation in Saturated Zone worksheet Figure 3 5 allows users to e Calculate an attenuation factor for the saturated zone if degradation occurs see Box 3 4 e Determine the concentration of the substance at a compliance point located down gradient of the drainage field see Box 3 4 and e Calculate a provisional discharge limit value see Box 2 2 Project information data such as site and substance details and dilution factor are automatically transferred to this worksheet from the previous sheets green cells The worksheet provides the following options brown cells 1 Degradation Three options are provided 1 No degradation occurs In this case the attenuation factor will be set as 1 2 Degradation occurs in the dissolved phase only degradation measured in the aqueous phase such as in aqueous laboratory experiments and the user will need to enter a half life for degradation This half life is likely to overestimate the rate of degradation in groundwater and therefore it is corrected by multiplying it by the retardation factor 3 Degradation occurs in the dissolved and sorbed phase degradation measured from field observations or laboratory experiments of the whole
30. ers in subsurface contaminant fate and transport modelling is provided in Environment Agency 20014 Factors to be considered in a sensitivity analysis are 1 Degradation rates Where sensitivity testing shows the derived permit limit is highly sensitive to the degradation rate the use of a half life of less than 2 years shows there is a need for robust justification to support the assessment 2 Thickness of the unsaturated zone For example relocating the drainage field if practical new discharges to an area characterised by a thicker unsaturated zone may result in an acceptable reduction in risk 3 Thickness of the drainage blanket Changing the design of the drainage blanket may result in an acceptable reduction in risk 4 Investigate the area dimension and orientation of the drainage field in relation to groundwater flow Increasing the area of the drainage field will decrease the rate of infiltration which may increase the potential for attenuation for example increased travel time through the unsaturated zone and dilution at the water table Changing the dimensions of the drainage field and or its orientation to groundwater flow for example increasing the length L of drainage field in direction of groundwater flow will increase H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 41 dilution although a check should be made that the dimensions are consistent with the area of the drainage field For
31. ficient Unsaturated Zone Thickness of unsaturated zone below drainage field Water filled porosity Bulk density of Unsaturated Zone Option to Select Degradation pull dow n Half Life for Instructions Enter the site details chemical water quality standard for example 0 5 mg l for Ammoniacal N user date and version The chemical information is taken through to subsequent sheets For Ammoniacal Nitrogen input 50 mg l for septic tanks 20 mg l for package treatment plants PTPs Select type from pull dow n list septic tank package treatment plant treatment plant or other Select User Specified if the discharge volume is available from the applicatant or if not select Calculated from the list If using the latter input Number of Persons Water Use litres person activity day using Flows and Loads 4 and Percolation Rate Vp to be provided by applicant from Percolation Test to British Standard BS 6297 2007 A1 2008 If you wish to proceed with the assessment whilstwaiting for the Percolation Test to be done assume Vp 50 Use the pull dow n to select Calculated or Specified If the applicant has a design for the drainage field and can specify the area Map provided by applicant together with NGR in Section 2c select Specified and enter value into Enter Area of Drainage Field To calculate the area Vp and Number of Persons will be required from p
32. h septic tanis and package treatment plants Number of persons lf the assessor moves the cursor over the red triangles at the corner of certain cells further information is revealed T T on the data required or equations solved Water use Percolation rate Discharge rate Calculated discharge Area of drainage fied and hydraulic loading Specify area of drainage field or calculate based on percolation rate Enter area of drainage field Calculated area of drainage field Calculated infiltration rate Data in green cells is automatically transferred from previous sheets Click on the brown cells and use pull down menus for other options The source of each value should be documented in the yellow cells on the worksheet and in any associated reports Ammonium From introdugtfon sheet Cr 3 90E 01 _ mg l From intrg uction sheet Varia Value Unit urce of parameter value c 6 00E 01 i e Septic tank p 5 00E 01 1 80E 02 litres person day Vp 1 00E 01 s mm Calculated discharge Q2 at 0 00E 00 md Q2 9 00E 00 m d Calculate A 0 00E 00 m A 1 25E 02 m Inf 7 20E 02 m d The outputs from each worksheet are provided in the dark grey cells Cells not used in the calculation are shaded out Figure 3 2 Examples of the main functionality The Infiltration System worksheet which has been used as an example here calculates the discharge and infiltration rates It can also calculat
33. hen call us on 03708 506 506 Mon Fri 8 6 Calls to 03 numbers cost the same as calls to standard geographic numbers i e numbers beginning with 01 or 02 email enquiries environment agency gov uk or visit our website www environment agency gov uk incident hotline 0800 80 70 60 24hrs floodline 0845 988 1188 amp Environment first Are you viewing this on screen Please ae consider the environment and only print if absolutely necessary If you are reading a paper copy please don t forget to reuse and recycle if possible
34. iltration System worksheet The Infiltration System worksheet Figure 3 2 allows you to specify the concentration of the substance in the treated effluent and to enter details of the infiltration system Project information data site and pollutant details are automatically transferred to this worksheet from the Introduction worksheet The Infiltration System worksheet provides the following options brown cells 1 Specify the type of treatment plant Four options are provided 1 Septic tank 2 Package treatment plant 3 Treatment plant 4 Other H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 13 For septic tanks and package treatment plants you can input the following information e Number of persons p Number of individuals served by the system This information is used to calculate total discharge and the area of the drainage field e Water use litres oerson day Typical rates of sewage generation in litres per person per day are given in British Water Flows and Loads 4 British Water 2014 e Percolation rate Vp The percolation rate should be taken from percolation tests undertaken according to BS6297 2007 A1 2008 This rate is used together with the number of persons to calculate the area of the drainage field See Box 3 1 2 Discharge rate Two options are provided 1 Enter the discharge rate 2 Calculate discharge rate this option is only available for septic tanks and
35. in the Saturated Zone worksheet will calculate the following e Attenuation factor for the saturated zone e Concentration of substance at a compliance point located down hydraulic gradient from the drainage field and e Provisional discharge limit value DLs Additionally e Decay rate for degradation e Hydraulic gradient the hydraulic gradient entered in the previous worksheet is corrected to ensure that groundwater fluxes up and down gradient of the drainage field balance e Soil water partition coefficient for non polar organics e Retardation factor e Groundwater flow velocity and rate of contaminant flow due to retardation e Graph Figure 3 6 showing variation in contaminant concentrations down gradient of the source It may be necessary to manually change the graph axes by clicking on the graph and selecting for format selected axes option scale in Excel and e Table giving calculated concentrations in groundwater between the source and the compliance point H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 28 This sheet calculates attenuation factor for the saturated zone substance concentration Attenuation in saturated zone at downgradient compliance point and discharge consent limit Input Parameters Variable Value Source Enter method of defining partition co efficient using pull down list User specified value for partition coefficient Substance Ammonium From int
36. l Calculations worksheet The hydrogeological calculations worksheet Figure 4 1 allows you to calculate a range of standard calculations that are frequently used by hydrogeologists Data requirements for some of the calculations are described in the comments boxes noted by a red tick in the corner of relevant cells The calculations performed are summarised below Table 4 1 Hydrogeological calculations These are independent of the worksheet calculations vv ci Groundwater flow velocity Time for GW to reach to receptor tew n x distance K i Volume of GW flowing through aquifer Q K A xI where A b x Retardation factor R R 1 Ka p n Contaminant flow velocity Veontam K i n R Time for contaminant to reach receptor teontam N Ri distance K 1 H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 36 Figure 4 1 Hydrogeological calculations worksheet Simple hydrogeological calculations hese calculations are provided to allow additional hydrogeological calculations to be undertaken if required Parameter symbol unit justification Hydraulic conductivity 1 00E 01 m d Hydraulic gradient i 1 00E 02 unitless Effective porosity of aquifer 1 00E 01 fraction Thickness of saturated aquifer 5 00E 01 Width of aquifer perpendicular to flow Distance to receptor 1 00E 02 m Bulk density of aquifer materials 1 80E 00 g cm Soil water partition co effi
37. ndwater flow w Background concentration of substance in groundwater Mixing zone thickness Concentration in groundwater at base of unsaturated zone Option to Select Degradation Half Life of Substance Bulk Density of Saturated Aquifer Materials Effective Porosity of Saturated Zone Option to Select Time Soil Water Partition Coefficient Cell L9 Define Dispersivity Distance to Compliance Point For most sites assume no by pass For Ammoniacal Nitrogen suggest value beween 0 5 and 2 I kg This is brought through automatically from Attenuation_unsatzone worksheet Specify from applicant s design f this is provided Assumed based on know ledge of aquifer for example 25 30 m for chalk 5 10 m for sandstone Enter using local know ledge or literature values examples sandstone 0 5 4 md chalk 1 to 30 md see also Aquifer Properties Manual Measure in GIS if Area groundwater contour shape files are available or assume 0 005 Check w hether w L is equivalent to the area of the drainage field although they may differ if the drainage field is at an angle to the flow direction For Ammoniacal Nitrogen assume 0 unless there is a known sewage discharge up gradient and you have confidence in anticipated background concentration For other substances refer to Regional GQMN data if appropriate Suggest use option to calculate mixing zone thickness This is brought through automatically f
38. olation tests undertaken according to BS6297 2007 A1 2008 sec mm H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 16 Concentration of substance in treated effluent discharge Number of persons Water use litres person day Percolation rate Discharge rate Area of drainage field H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 17 Measured or taken from an agreed reference Number of people served by the septic tank or package treatment plant Information on typical rates of sewage generation can be obtained from British Water 2014 Rate should be determined as set out in BS6297 2007 A1 2008 Measured or calculated based on number of persons or water use Measured or calculated based on number of persons and percolation rate Must be input Dependent on option selected Dependent on option selected Dependent on option selected 3 4 Attenuation in Unsaturated Zone worksheet The Attenuation in Unsaturated Zone worksheet Figure 3 3 allows you to e calculate an attenuation factor if degradation occurs for the drainage layer if present e calculate an attenuation factor if degradation occurs for the unsaturated zone e determine the concentration of the substance at the base of the unsaturated zone and e calculate a provisional discharge limit value This limit may be superseded if dilution and attenuation in the
39. onery Office Environment Agency 2000 Guidance on the assessment and monitoring of natural attenuation of contaminants in groundwater R amp D Publication 95 Environment Agency 2001a Guide to good practice for the development of conceptual models and the selection and application of mathematical models of contaminant transport processes in the subsurface National Groundwater and Contaminated Land Centre report NC 99 38 2 Solihull Environment Agency 2001b Benchmarking and guidance on the comparison of selected groundwater risk assessment models National Groundwater and Contaminated Land Centre report NC 00 14 Solihull Environment Agency 2001c Guidance on the assessment and interrogation of subsurface analytical contaminant fate and transport models NGWCLC report NC 99 38 1 Solihull Environment Agency 2001d Guidance on assigning values to uncertain parameters in subsurface contaminant fate and transport modelling National Groundwater amp Contaminated Land Centre report NC 99 38 3 Solihull Environment Agency 2003 Review of ammonium attenuation in soil and groundwater NGWCLC report NC 02 49 Solihull Environment Agency 2004 ConSim Contamination impact on groundwater Simulation by Monte Carlo method Prepared by Golder Associates UK Ltd Environment Agency 2011a H1 Environmental Risk Assessment Groundwater risk assessment for treated effluent discharges to infiltration systems Environment Agency 2011b
40. or inorganics such as metals and ammonium 2 Calculate partition coefficient non polar organic substances only based on fraction of organic carbon and organic carbon partition coefficient see Box 3 2 This option applies to the drainage layer and the unsaturated zone H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 18 A summary of the data requirements blue cells for this worksheet is given in Table 3 3 Depending on the options selected the worksheet will automatically grey out cells for which data entry is not required The worksheet will calculate the following See also Box 3 2 Attenuation factor for the drainage layer Attenuation factor for the unsaturated zone Concentration of substance at base of the unsaturated zone and Provisional discharge limit value DL Additionally the worksheet will calculate Dispersivity taken as 10 of the thickness of the unsaturated zone Decay rate for degradation Soil water partition coefficient for non polar organics Retardation factor Unretarded travel time of substance through the drainage layer and unsaturated zone with no dispersion Unretarded and retarded travel time through the drainage layer and unsaturated zone with dispersion H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 19 Figure 3 3 Attenuation i in Unsaturated Zone worksheet Attenuation unsaturated zone Fromintroduction sheet mgA
41. organic carbon of aquifer material Equation 2 IC Retardation Factor Rf in the saturated zone is calculated from Rf 1 Kd n p Equation 3 where n effective porosity of aquifer material fraction if fissure porosity used the partition coefficient should be set as 0 p dry bulk density of aquifer g cm Values for dispersivity are calculated using either 1 Xu and Eckstein a 0 83 log x 4 Equation 4 a 0 01x and a 0 001x or 2 a 0 1x and a 0 01x and a 0 00 lx Equation 5 where x Az y longitudinal transversal and vertical dispersivity m X distance to down gradient compliance point m The worksheet adjusts the hydraulic gradient i as follows DF a ladjusted 7 H DF DF dilution factor Equation 6 This adjustment is undertaken to ensure that groundwater fluxes up and down gradient of the drainage field balance H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 32 Box 3 4 continued The unretarded groundwater velocity v through the saturated zone is calculated from v Ki n Equation 7 The retarded groundwater velocity u through the saturated zone is calculated from u v R Equation 8 K hydraulic conductivity of aquifer in which dilution occurs m d The attenuation factor AFs for the saturated zone is calculated from where erf and erfc are error function and complementary error functions respectively H1 Annex J5
42. package treatment plants see Box 3 1 3 Area of drainage field Two options are provided 1 Enter the area of the drainage field 2 Calculated area of the drainage field this option is only available for septic tanks and package treatment plants see Box 3 1 A summary of the data requirements blue cells for this worksheet is given in Table 3 3 Depending on the options selected the worksheet will automatically grey out cells for which data entry is not required The Infiltration System worksheet calculates the following results e Discharge rate m day based on the number of persons and water use this option is only available for septic tanks and package treatment plants e Area of the drainage field m based on the number of persons and percolation rate derived from testing this option is only available for septic tanks and package treatment plants e Infiltration rate m day over the discharge area This rate is used in subsequent calculations H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 14 Complete each of the blue cells the cells coloured blue will vary depending what other parameters are selected Infiltration System Substan Compliance value or environmental standard Input Parameters Standard entry Concentration of substance in substance in discharge entering infiltration system Type of treatment plant Water use and percolation rate for use only wit
43. project 2000 MS 15 M1 The Hydraulic Performance and Efficiencies of Different Subsoils and the Effectiveness of Stratified Sand Filters Environmental RTDI Programme 2000 2006 The worksheet is currently being tested for use on later versions of Microsoft Excel and other Microso operating systems ft M H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 4 1 0 Overview An illustration of a typical setting for which the InfWS could be used is given in Figure 1 1 Figure 1 1 Discharge of treated effluent to infiltration systems and application of the InfWS Drainage Field Width of Drainage W gt Field Downgradient Compliance Point SECTION i Downgradient Length of Drainage Field Distance to Compliance Point Compliance L x gt Point hickness of Infiltration Unsaturated Inf Zone Mixing Zone Thickness Groundwater Flow gt You can use the InfWS to e calculate the area of the drainage field e calculate the average infiltration rate over the drainage field e determine attenuation within the drainage blanket and the unsaturated zone and calculate the concentration of the substance of concern at the water table H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 5 e determine the dilution factor for non hazardous pollutants and calculate their concentration in groundwater immediately down gradient of the drainage field e dete
44. revious step This is carried through automatically from Infiltration Systemw orksheet May be indicated by applicant For a British Standard use a value of 0 3 m Suggest a value of between 20 and 30 Suggest a value of 1 75 g cm Select Degradation Occurs Solid and Dissolved Phases Although for an initial conservative assessment suggest select No degradation option Suggested half life of 1 to 2 years for ammonium For Ammoniacal Nitrogen suggest value beween 0 5 and 2 I kg Enter thickness between drainage field base and water table Figure 1 Enter using local know ledge or literature values examples sandstone 0 15 15 chalk 0 02 2 Enter literature values Suggest value of 1 75 g cm Select Degradation Occurs Solid and Dissolved Phases Although for an initial conservative assessment suggest select No degradation option Suggest haf life of 2 to 5 yearsfor ammonium H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 45 Dilution Attenuation_satzone Degradation of Substance days Fraction of Rapid Flow through unsaturated zone Soil Water Partition Coefficient Concentration at base of unsaturated zone Length of drainage field in direction of groundwater flow L Saturated Aquifer Thickness m Hydraulic Conductivity of Aquifer Hydraulic gradient of water table Width of drainage field perpendicular to grou
45. rge with the aim of preventing the input of hazardous substances to groundwater or pollution due to the input of non hazardous pollutants The dilution factor describes the amount of dilution of the discharge by groundwater flow and is calculated from the ratio of groundwater below the drainage field and the discharge to the drainage field The attenuation factor in the drainage blanket can be calculated as the ratio between the concentration of the substance in the treated effluent and the predicted concentration at the base of the drainage blanket The attenuation factor in the unsaturated zone can be calculated as the ratio between the concentration of the substance at the base of the drainage blanket and the predicted concentration at the base of the unsaturated zone The attenuation factor in the saturated zone can be calculated as the ratio between the concentration of the substance in groundwater below the drainage field and the predicted concentration at a point down gradient of the drainage field H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 6 Box 1 1 continued Environmental standard The environmental standard used to derive the compliance values will depend on a whether the substance is a hazardous substance or a non hazardous pollutant and b the use of the receptor for example a potable abstraction or surface water Examples of environmental standards are e Limits of detection or
46. rmine attenuation within the saturated zone for non hazardous pollutants and calculate their concentration at a point down gradient of the drainage field and e determine provisional discharge limit values Box 1 1 contains a definition of some of the main terms used in this document Box 1 1 Definition of standard terms Compliance point Compliance value Discharge limit value Dilution factor Attenuation factor drainage blanket Attenuation factor unsaturated zone Attenuation factor saturated zone Acompliance point is a suitable point along the substance pathway between the source and a receptor at which a compliance value can be set The compliance point may be a virtual point for the purpose of predictive assessments or it may be a physical monitoring point such as aborehole In some cases the compliance point may be the receptor itself This is a concentration at the compliance point that should not be exceeded Depending on the level of assessment a compliance value may take account of some or all of the dilution and attenuation processes along the substance pathway to the receptor s The purpose of the selected compliance value is to provide protection to a down gradient receptor provided the compliance value is met the relevant environmental standard for the receptor s should also be met A discharge limit value is a value set as a condition in the permit to control a specified substance in the discha
47. roduction sheet Compliance value or environmental standard Cr 3 90E 01 From introduction sheet Entry if specify partition coefficient option Source concentration Ce 6 00E 01 From infiltration sheet Soil water partition coefficient 2 00E 00 Vkg Dilution Factor DF 1 95E 00 from dilution sheet Entry for organic chemicals option Unsaturated zone attenuation factor 3 65E 00 From atten_unsatzone sheet Fraction of organic carbon in aquifer 2 oe fraction Organic carbon partition coefficient V kg Soil water partition coefficient 2 00E 00 Vkg Variable Value Unit Source of parameter value Concentration in groundwater below drainage field Cgw 8 41E 00 mg l from dilution sheet Option to select degradation Degradation occurs sorbed and dissolved phases _ ine di ivity click brown cell and use pull down list Half life for degradation of substance tie 7 30E 02 days if Dispersivity based on Xu amp Eckstein 1995 Calculated decay rate 2 9 50E 04 days calculated very low value set if no degradation Width of drainage field 1 00E 01 m from dilution sheet Enter value Calc value Xu amp Eckstein Mixing zone thickness 8 57E 00 m from dilution sheet Longitudinal dispersivity m Bulk density of aquifer materials 1 80E 00 g cm Transverse dispersivity m Effective porosity of aquifer 1 00E 01 fraction Vertical dispersivity m Hydraulic gradient 4 10E 02 fraction from dilution sheet adjus
48. rom Dilution w orksheet Select Degradation Occurs Solid and Dissolved Phases Assume 1850 days 5 years for Ammoniacal Nitrogen See also Small Sew age Discharges SSDs SPZ1 risk assessment approach Enter using local know ledge or literature values examples 1 65 g cm for Chalk Enter using local know ledge or literature values examples 0 02 for Chalk 0 10 for Sherwood Sandstone Select Steady State For Ammoniacal Nitrogen suggest value beween 0 5 and 2 I kg For intergranular aquifers select Xu amp Eckstein for fissured aquifers select 10 option This factor is significant in its effect on compliance If site is inside SPZ1 for sensitivity select 50 minitially to do assessment then enter the actual distance measured in GIS to the vulnerable receptor the PWS source spring or watercourse based on location provided by applicant Map provided by applicant together with NGR in Section 2c of Permit application form combined with GIS measurement to nearest receptor H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 46 Concentration at This will provide the calculated concentration at the compliance point and state Compliance whether the application meets or exceeds the threshold Point output of assessment H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 47 Would you like to find out more about us or about your environment T
49. saturated zone are taken into account Project information data Such as site and substance details and infiltration rate are automatically transferred to this worksheet The Attenuation in Unsaturated Zone worksheet provides the following options brown cells 1 Degradation Three options are provided 1 No degradation occurs In this case the attenuation factor will be set as 1 2 Degradation occurs in the dissolved phase only degradation measured in the aqueous phase such as in aqueous laboratory experiments and the user will need to enter a half life for degradation This half life is likely to overestimate the rate of degradation in groundwater and therefore it is corrected by multiplying it by the retardation factor 3 Degradation occurs in the dissolved and sorbed phase degradation measured from field observations or laboratory experiments of the whole system that is both the dissolved and sorbed phases and the user will need to enter a half life for degradation This half life will be used in the calculation of an attenuation factor This option applies to the drainage layer and the unsaturated zone It is essential that you should be able to support the case for degradation Please refer to Section 5 0 If no evidence for degradation is provided you should select the option No degradation occurs 2 Soil water partition coefficients Two options are provided 1 Specify partition coefficient typically used f
50. sion 2 0 34 Summary of calculations for concentration of substance in groundwater No input required values taken from previous worksheets Summary of compliance data attenuation and dilution factors Substance Effluent concentration Compliance value or environmental standard Distance to compliance point Attenuation factor unsat zone Dilution Factor Attenuation factor sat zone Predicted concentrations at compliance point Concentration at base of unsaturated zone Concentration in groundwater below drainage field Concentration in groundwater at compliance point Provisional discharge limit values Based on attenuation in unsaturated zone Based on attenuation in unsaturated zone and dilution Based on dilution and attenuation in unsaturated and saturated zone Ammonium 6 00E 01 0 39 50 00 3 65E 00 1 95E 00 3 54E 00 1 64E 01 8 41E 00 2 38E 00 1 43E 00 2 78E 00 9 84E 00 Predicted concentration 1 000 000 100 000 10 000 1 000 0 100 Log Concentration mg I 0 010 0 001 Effluent Base unsat zone Dilution Compliance borehole H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 35 Attenuation in unsaturated zone only Dilution taken into account Attenuation in saturated zone taken into account 4 0 Additional worksheets 4 1 Hydrogeologica
51. system that is both the dissolved and sorbed phases and the user will need to enter a half life for degradation This half life will be used in the calculation of an attenuation factor It is essential that you should be able to support the case for degradation Please refer to Section 5 0 If no evidence for degradation is provided you should select the option No degradation occurs 2 Partition coefficients Two options are provided 1 Specify partition coefficient typically used for inorganics such as metals and ammonium H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 27 2 Calculate partition coefficient non polar organic substances only based on fraction of organic carbon and organic carbon partition coefficient see Box 3 2 3 Dispersivity Three options are provided 1 Enter user defined dispersivity values 2 Calculate dispersivity based on length of flow path see Box 3 4 3 Calculate dispersivity using Xu and Eckstein 1995 see Box 3 4 4 Time Two options are provided 1 Steady state Use this to determine discharge limit values 2 Enter time Use this to validate the assessment if monitoring data are available A summary of the data requirements blue cells for this worksheet is given in Table 3 5 Depending on the options selected the worksheet will automatically grey out cells for which data entry is not required 3 7 Calculated parameters The Attenuation
52. ted Note values of dispersivity must be gt 0 Hydraulic conductivity of saturated aquifer 5 00E 00 m d from dilution sheet Distance to compliance point 5 00E 01 m Xu amp Eckstein 1995 report ax 0 83 log ox az ax 10 ay ax 100 are assumed Option to select time Use steady state recommended _ For calculated value assumes ax 0 1 x az 0 01 x ay 0 001 x Enter time 1 00E 02 days time variant options only Time since pollutant entered groundwater 1 00E 99 Parameters values determined from options Partition coefficient Kd 2 00E 00 l kg see options Longitudinal dispersivity ax 2 98E 00 m see options Transverse dispersivity az 2 98E 01 m see options Vertical dispersivity ay 2 98E 02 m see options Calculated Parameters Variable Value Unit Groundwater flow velocity v 2 05E 00 m d Retardation factor Rf 3 70E 01 fraction Decay rate used 9 50E 04 g Hydraulic gradient used in aquifer flow down gradient icore 4 10E 02 fraction Rate of contaminant flow due to retardation u 5 54E 02 mid Attenuation factor AFs 3 54E 00 fraction Attenuation and Dilution factors and discharge consent limit Dilution Factor DF 1 95E 00 Unsaturated zone attenuation factor AFu 3 65E 00 Saturated zone attenuation factor AFs 3 54E 00 Concentration in groundwater at compliance point Cacp 2 38E 00 or Discharge limit value DL 9 84E 00 Distance to compliance point 50
53. ted zone and substance concentration in groundwater down gradient of the drainage field Additional calculations Data entry and computation of simple hydrogeological calculations Summary Summary of results of calculations of impact of the discharge on groundwater and provisional discharge limit values Ammoniumcalculator Data entry and conversion for different laboratory analysis of ammonium Porosity calculator Data entry and calculation of water filled porosities Attenuation Calculation of attenuation factor in the saturated zone calc_sat_zone Data entry is only possible in eight of the worksheets as highlighted in blue in Table 3 1 Each of these eight worksheets also presents the results of each calculation The calculations themselves are carried out in the remaining worksheets which are provided for reference H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 11 Each worksheet is password protected and data may only be entered in specific cells The cells are colour coded as detailed in Table 3 2 Table 3 2 Colour scheme for the worksheets Blue cells require data to be entered to either perform a specified calculation or to record site details Data may take the form of either site details as text on the Introduction sheet or values for identified parameters on all other sheets All blue cells must be completed for each assessment type Brown cells are pull down menus where options can b
54. terature values where their application is supported by field data Any literature used must relate to the behaviour of the chemical under similar environmental conditions for example redox pH contaminant concentrations temperature presence of other substances etc Guidance on assessing contaminant attenuation is given in Environment Agency R amp D Publication 95 Guidance on the assessment and monitoring of natural attenuation of contaminants in groundwater Environment Agency 2000 If you are assessing contaminants that are not subject to degradation such as heavy metals non radioisotopes and chloride or there is no evidence of degradation from field data you should select the No degradation occurs option For preference you should obtain the degradation rates from studies which give a degradation rates that apply to both water and soil If you have derived degradation rates from laboratory experiments based on water as the only phase this will overestimate the rate of degradation in groundwater in which case you should select either the option No degradation occurs or Degradation occurs in the dissolved phase only H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 39 5 0 epean of ea There are a number of critical factors for which there can be limited supporting literature or field data In such cases the user is recommended to consider the following factors 1 Dilution Factors
55. through fraction Set as 0 if no by pass Must be the unsaturated zone input Fraction of organic carbon foc Expressed as a fraction Must be for the drainage layer and foc between 0 and 1 input when unsaturated zone non polar organic chemicals option is selected Organic carbon partition Koc Contaminant specific value Must be coefficient of substance Kocs which describes the input when partitioning of a substance non polar between organic matter and organic water chemicals option is selected Soil water partition Kd Describes the partitioning of Dependent coefficient for movement of Kd a substance between water on option contaminant through and the soil matrix in the selected drainage layer and unsaturated zone Soil unsaturated zone water partition coefficients will typically be derived from literature sources H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 21 laboratory column experiments or field data where comparison with a conservative tracer is possible If a literature source is used it is important to ensure that it is relevant to the unsaturated zone material For conservative contaminants the Kd value should be set at zero Box 3 2 gives an overview of the standard equations used in the Attenuation in the Unsaturated Zone worksheet Box 3 2 Standard equations for Attenuation in Unsaturated Zone worksheet Decay rate A is calculated from A In 2 H Equation
56. ution worksheet will calculate the following see Box 3 3 e Dilution factor to account for dilution by groundwater flow below the drainage field e Concentration of substance in groundwater immediately down gradient of the drainage field and e Provisional discharge limit value DL H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 24 Box 3 3 Standard Equations for the Dilution worksheet The dilution factor DF for groundwater below the drainage field can be calculated from Gw Inf A Ci Gw Cu Inf A C DF Equation 1 and Gw K i wa Mz Equation 2 where Gw groundwater flow mixing zone below drainage field m d K hydraulic conductivity m day i hydraulic gradient wa width of disposal field perpendicular to flow direction m M mixing zone thickness m Inf infiltration rate m day A area of drainage field m Environmental standard used to derive compliance value mg l C background concentration of substance in groundwater immediately up gradient of discharge field mg l The mixing zone thickness can be calculated as follows M VO0 01120 tadji opf EME Equation 3 LAA where L length of drainage field parallel to groundwater flow m da aquifer thickness m H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 25 Table 3 4 Summary of data requirements for the Dilution worksheet blue cells L
57. vesiacstscsssenicsatenisendccesncsctacsasncacssacestbacsecasseevsee 34 4 0 Additional worksheets cccceeeseeseeessseeceeeeesesnesssceeceeeeeeeesesssaceeseseeeenaesssanaeseeseess 36 4 1 Hydrogeological Calculations worksheet ccsccseeeceseeeeeeeeeeseseeeseseeeeeseeeenseeeeeeeeeeees 36 4 2 Ammonium Conversion worksheet cccccecessessesscseceeeeeeeseessssneeeeseeesneenessssanenees 37 4 3 Porosity Calculator WOMSINCCE isieiicns cis scniseccsninscanscsaanncsnnccuindnscasawsandeuseicnsusssnasetacnstianssd 37 Poh OU co gs 70 epee no ne PP ne ee ne eee ene renee t 39 5 0 LEVEY OPS tation of res liSnsnsusnsssnn a a a a 40 6 0 Sensitivity ANOIVSIS amra E a 41 7 0 Assessment of results cccscccseeceescsseesssseeeceeeeesesseescaeeeseeeseeeasessscaeeeseeesasnasessaneeseeseess 42 Refere meeS aer a e eete ce cy escueupustcecs cyeisensuavadeeeestieeeessditecce 43 Pesola D e E E E A E E A E A E E E E E 45 H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 1 Below is a summary of changes made to this Annex since the launch in February 2011 Annex Date Change Template version version 1 2 Nov 2011 Reformatting to respond to general H1 April 2011 issues raised in the 2010 H1 public consultation Minor review of text and layout 2 0 Dec 2014 Infiltration worksheet tool amended H1 April 2011 to represent drainage layer Error in dilution factor calculation fixed Minor
58. where applicable a Minimum Reporting Value MRV MRVs are typically used to assess the discernibility of hazardous substances as a basis for deciding whether their input has been prevented Natural background up gradient quality This might be used to assess the discernibility of hazardous substances where background concentrations are higher than detection limits or the MRV Alternatively it might be used for non hazardous pollutants where the natural background concentration exceeds the relevant standard such as a drinking water standard DWS or environmental quality standard EQS DWS Drinking Water Standard or EQS Environmental Quality Standard In some cases it will be appropriate to use lower concentrations than the DWS or EQS to provide satisfactory protection to a receptor For example it may be suitable to apply a safety factor to provide greater security to an existing drinking water supply Such as 0 75 x DWS In other cases where the DWS or EQS represents a significantly higher concentration than the natural background quality use of such values might represent a significant level of deterioration for example a DWS of 250 mg l of chloride compared to a background concentration of for example 30 mg l In these cases you may need to discuss this with us and derive a more suitable value between the MRV or background concentration and the EQS or DWS H1 Annex J5 Infiltration Worksheet user manual December 2014 version
59. xt It is appropriate to use the InfWS for larger discharges 15m day or more or those which have been identified as needing to progress to a higher level of assessment Level 2 prior examination The InfWS should only be used by suitably experienced hydrogeologists or those fully conversant with our approach to groundwater risk assessment and the relevant legislation and guidance The InfWS can also be used as a tool to help refine the location of the discharge the design of the structure and the level of treatment of the effluent prior to discharge This can be supported by the use of sensitivity analysis The previous version of the InfWS version 1 2 has been updated as follows 1 The drainage blanket within an infiltration system drainage field is now represented which allows attenuation in the drainage blanket and unsaturated zone to be considered separately This modification was based on research by the Irish H1 Annex J5 Infiltration Worksheet user manual December 2014 version 2 0 3 Environment Protection Agency that suggests attenuation mainly occurs within the drainage blanket 2 Acheck has been added to flag any inconsistency between the area of the drainage field entered or calculated in the Infiltration sheet and the area calculated in the Dilution sheet see Table 3 4 3 An appendix has been added which gives guidance on input values 4 The equation used to calculate the dilution factor has

Annex J5 - Infiltration Worksheet user manual

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