Green Infrastructure
Contents
1. eee SediSand Filter to activate the associated ia hyperlink or hover over the associated text to view the cell comment boxes These efficiencies can be updated to reflect local practices Please note that green roof efficiencies are currently set to City of Austin best practices which require that green roofs be attached to a rainwater harvesting system for which 100 pollutant efficiency is assumed Building pollutant loads are assumed to be completely treated by green roofs and water harvesting when those controls are selected If rainwater harvesting for a parking area is selected in the app physical inputs section the app will assume all parking pollutant loads will be treated by rainwater harvesting Otherwise if more than one control type is used building parking and landscaping loads are assumed to be treated by biofiltration rain gardens and conventional controls according to the percentage of water captured by each control See the Treatment Allocations for Landscape Devices section in the app These removal loads can be viewed in the calculation tables Treated by 9 Area sf Annual Load Ibs Green Roof GreenRoofwiCistern Water Harvesting Biofiltration Rain Gardens Sed Sand Filter Total Ibs 30 3 18 17 0 0 0 C mal Area st ol Ug 1 Bnei eer E E 32 437 97 onar Wr i 2 178 98 93 100 od C mg l Area sf Annual Load Ibs Green Roof GreenRoofwiCistern Water Harvestin2. enewtits or otner eco OgiCal services First 3 mm of Runoff Rho Sediment Trap 0 46 m 0 61 m Send Filter Underdrain with i mo Geotechnical Filter Cloth http environment fhwa dot gov ecosystems ultraurb 3fs8 as City of Austin Urban Design Division 8 Envision Tomorrow Green Infrastructure App Prototype Builder Preset Buttons To select the methods for handling water quality requirements in the Prototype Builder the user may choose from four pre set buttons on the Green Infrastructure tab No green infrastructure assumes conventional controls such Green Infrastructure Presets as the sedimentation sand filter previously described will be used noi No Green to treat the minimum volume of stormwater required to be are captured Minimum Green Infrastructure will automatically select green oo Minimum Green infrastructure controls depending on the site configuration in the Infrastructure Prototype Builder in order to satisfy the minimum water quality capture volumes If there is enough landscaping area set aside rain gardens will be selected followed by biofiltration rainwater harvesting and finally green roofs connected to a cistern when there is not enough landscaping to accommodate other less expensive controls The app will determine the necessary size of No water quality controls amp No fee in lieu the green infrastructure control based on commonly used default depths and
3. Dietz Michael 2007 Low Impact Development Practices A Review of Current Research and Recommendations for Future Directions Springer Science Business Media B V http link springer com article 10 1007 s11270 007 9484 z Gregoire Bruce and Clausen John 2011 Effect of a modular extensive green roof on stormwater runoff and water quality Ecological Engineering 37 http clear uconn edu projects tmdl library papers Gregoire Clausen 2011 pdf Grey Mark et al Feb 13 2013 The Costs of LID Low impact development BMP installation and operation and maintenance costs in Orange County CA Stormwater http www stormh20 com SW Articles 20426 aspx page 1 Guildford County North Carolina Guildford County Innovative Stormwater Device Fact Sheet Green Roof http www co guilford nc us watershed_ cms bulletins Green 20Roof 20Factsheet pdf Hardin and Wanielista 2007 Designing cisterns for green roof in Florida University of Central Florida Stormwater Management Academy http www stormwater ucf edu conferences 9thstormwaterCD documents DesigningCisterns pdf International Stormwater BMP Database December 2010 Pollutant Category Summary Fecal Indicator Bacteria http www bmpdatabase org Docs BMP 20Database 20Bacteria 20Paper 20Dec 202010 pdf Li Ming Han et al July 2010 Bioretention for stormwater quality improvement in Texas pilot experiments Texas Transportation Institute http d2dtl5nnlpfrOr cloudfront net tti tamu edu d
4. Inputs The only inputs required for this section are annual rainfall and in the case of the national model the percentage of annual rainfall producing runoff the default is ninety percent Because the amount of pollutants removed is reported as a percentage in the summary in the Prototype Builder the amount of annual rainfall may not appear to have an impact in the summary however it will impact the total annual pounds reported as building types are aggregated across scenarios in the Scenario Builder City of Austin Urban Design Division 12 Envision Tomorrow Green Infrastructure App Prototype Builder Load Calculations The app uses the Simple Method to calculate Annual Runoff the pollutant loads While there are more 1 eee eee complex models this method has been shown ae to produce reasonable results This method RR ee ace ane ae considers the annual rainfall the runoff ee Pe ere mil coefficient the pollutant concentration and the l Ce ee a a area in acres The runoff coefficient which is ee based on the amount of impervious cover was 695 Total Nitrogen smn C mail Area sf previously calculated to estimate required at lads voit volumes whether for the National stormwater model or the locally calibrated model Varying pe C mgA EER a levels of pollutant concentrations are n i ze 0 009 associated with different types of land uses je Based on the land use types selected on
5. including reducing building energy requirements reducing air pollution and sequestering and reducing carbon emissions all of which are measured approximately in the Scenario Builder They also provide an aesthetically appealing amenity and potential habitat Green roofs that are not designed to be occupied are called extensive and feature a thinner substrate and lower construction costs Intensive green roofs involve a thicker substrate and are designed to accommodate eS recreational use by residents serving as rooftop open space http winterstreetarchitects files wordpress com 2010 08 intensive green re Some green roofs are also used for rooftop gardening Green Roof Connected to Rainwater Harvesting System Green roofs can be connected to cisterns to Fh mame improve water collection efficiencies and provide a water source for the green roof between storm events In the case of Austin Texas the region experiences long periods with minimal rainfall punctuated by large storms combined with hot summers and a high rate of evaporation City best practices recommend a green roof tied to a cistern that captures a much higher portion of stormwater approximately 65 This stored water is used to re irrigate the rooftop with all captured water ultimately being processed through the system Because of this pollutant treatment efficiencies of a green roof with cistern are assumed Design Stanley Studio dite i
6. A EE T A E A E E E A E E E eee 22 R CNC SS i E S E E N E yan ee sanuaeeavenneas 25 City of Austin Urban Design Division i ENVISION COMOlOW Green Infrastructure App Introduction The Green Infrastructure App allows the user to consider water quality needs when developing a building prototype in the Envision Tomorrow Plus tool The resulting benefits particularly from green infrastructure are also measured across a planning area in the Scenario Builder component of the tool During a storm event generally the initial runoff from impervious surfaces parking lots sidewalks roofs is the most polluted For this reason many communities require a minimum volume of water be captured and treated before release into a stormwater system creeks rivers and the surrounding environment The Green Infrastructure App calculates the volume of water typically required to be treated and allows the user to choose either conventional or green infrastructure water quality controls to meet those treatment needs The app will also calculate the costs of the chosen controls and the estimated removal for key pollutants When green infrastructure controls are chosen the annual benefits are quantified in the Scenario Builder according to the Center for Neighborhood Technology guide The Value of Green Infrastructure Green infrastructure frequently referred to as Low Impact Development LID principally uses plants and soil to remove pollutants from runoff
7. IR CSIC a esetecaedetesettpellc scm RAR a ee dE reer on eS eA 118 13 120 Industrial Total Mitroges mgl Building Tape Mational simple method i Mational simp i Mational Pesidential OR MA A A A a A a N earciteoser ements Rea OTIC EI osiesciesinsesastsetvntsientnsnectee a E A E E E eee 124 125 126 Lead Pb mgl Building 127 28 Residential Industrial Type Mational simple method i ational simp i Mational 123 Comme i aL 130 131 132 F Coli 1 000 colosies ml Building 133 134 Residential Industrial Type ational simple method i Mational simp i Mational 135 Commercial oe pee cayerech ise bcesuiesna sn esnir sar A REE REE TE REET Ree EERE Ea CT EEE Tr SEE Pa CER ae are a ee ieee i aE En EA ene oe Ta Ree OAOE E eR E O RSET City of Austin Urban Design Division 13 Envision Tomorrow Green Infrastructure App Prototype Builder Once the pollutant loads are estimated the app will estimate the amount of pollutants removed by the various stormwater controls selected using treatment efficiencies listed in the following table and based on a literature 139 Treatment Efficiencies oss tm cot review specified in the app reference Section For More WHO GICER ROOF l ren 0 eae ie ee Me Q 141 information on specific CERNE S O 1 O 1 cman coccoeneddt wee Aan ae f O O ee A fe efficiencies click on the cell
8. a Prototype Builder Physical Inputs Percent of building footprint used as a Green Roof Green roof media depth Green roof capture efficiency Green roof connected to Rainwater Harvesting system Green roof water harvesting depth Green roof water harvesting efficiency equivalent T X 3 5 cisterns Green roof area needed for harvested water Percent of building footprint uzed for Rainwater Harvesting not inluded in green roof rainwater harvesting Rainwater harvesting depth Rainwater harvesting efficiency Rainwater harvesting of parking area structure equivalent T x 8 5 cisterns enter percentage 20 enter percentage Landscaping area needed D square feet Percent of landscaping open space used for Biofiltration Biofitration media depth Biofitration capture efficiency Percent of landscaping open space used for Rain Gardens Rain garden depth enter percentage 0 enter percentage 945s enter percentage Rain garden capture efficiency of site required for Conventional Facility Underground Conventional Facility Capture Efficiency gag enter percentage retention Please note the rainwater harvesting depth refers to the depth of the harvesting area and NOT the cistern depth For conventional facilities a depth of four feet is assumed Additional inputs include the option to collect rainwater from parking areas and or structures and to connect gre
9. capture efficiencies Green Infrastructure Medley will assign a mix of rain gardens rainwater harvesting and green roofs attached to a cistern Rainwater falling on fifty percent of the building footprint will be treated by a green roof attached to a cistern with the remaining half captured by other cisterns Fifty percent of the landscaping area will accommodate rain gardens This setting will generally exceed the minimum required volume of stormwater with the accompanying environmental and aesthetic benefits as well as the additional water available for irrigation between storm events No water quality controls amp No fee in lieu will ignore any water quality needs for the building prototype by setting Fee in lieu to yes and setting the fee amount to SO See Stormwater Costs for more information When calculating the square footage of a control and the volume of water treated by the control the app uses its capture efficiency either as defined by the preset button or customized by the user This information can be viewed in the dashboard of the Green Infrastructure tab by selecting the first sign to the left to expand the Green Infrastructure Outputs section To the right is a pie chart detailing the percentage of the site occupied by each type of green infrastructure control 12 a B C D E p 1 Green Infrastructure Stats m P B o6 Site Layout with Stormwater Features 3 Water quality capture depth in
10. efficiencies found in the Treatment Efficiencies lookup table The default values are based on a literature search with specific sources listed for each efficiency but these values can be adjusted to reflect local practices Pollutants removed annually TSS TN and TL bs 0 226 Annual Runoff in Pollutant Concentration according to lookup table mg l Applicable Area sf 43 560 sf acre Captured Volume Assumed Treated Control Treatment Efficiency as listed in lookup table Pollutants removed annually F Coli billions of colonies 103 Annual Runoff in Pollutant Concentration according to lookup table mg l Applicable Area sf 43 560 sf acre Captured Volume Assumed Treated Control Treatment Efficiency as listed in lookup table Captured Volume Assumed Treated default 92 NOTE The app sizes controls by taking into consideration their water capture efficiency and presumes formulas used for calculating required water quality volumes capture annual runoff City of Austin Urban Design Division 16 Envision Tomorrow Green Infrastructure App Prototype Builder Appendix B Prototype Builder Local Customization Changing the Local Stormwater Model If local water quality required volumes are based on impervious cover and runoff coefficients the Green Infrastructure app can be customized to reflect local standards for water quality capture Initially calibrated for Austin Texas the app references two sets of requirement
11. the e a Physical Inputs tab of the Prototype Builder and es SMe the stormwater model selected the app will look up pollutant concentration levels for building types and associated landscaping and parking Using the square footages calculated across the site in the Physical Outputs tab the app will calculate pollution loads across the site The pollutant concentration lookup tables list national levels found in various studies as noted in the New York State Stormwater Management Design Manual Local pollutant levels are currently calibrated to those found in the City of Austin Environmental Criteria Manual These values may be updated to reflect other local criteria Please note since residential pollutant loads are typically based on the single family building type the app will only categorize single family and townhouse selections on the Physical Inputs tab as Residential Unless Industrial is indicated all other land use types will be categorized as Commercial for the purposes of pollutant estimation by the app To view these calculations and the lookup tables click on the expansion button l below the pollutant summary 13 Lookap Tables 114 Total Saspemded Solids mgil Building Lasd caping Parking 15 Type National simple method i National simp in Mational simple method HUES Rezidential cacessastacasciceeleactvdeiestl snes RR eR eee ree UE OT eS en Ore tert Ann een een eel ete
12. to be one hundred percent The app will estimate the area of 5 TTT E E green roof needed to drain down the cistern and will flag the City of Austin Urban Design Division 6 Envision Tomorrow Green Infrastructure App Prototype Builder user if the selected green roof area combined with the landscaping area is not sufficient To give a sense of the amount of water collected the app will also calculate the number of cisterns needed measuring 7 feet in diameter by 8 5 feet high however cisterns can be designed in many shapes and sizes Rainwater Harvesting Rainwater harvesting is collecting rain that falls on rooftops and structures and storing it for pollutant removal efficiency currently in the app assume that rainwater will be used for landscaping irrigation to achieve a 90 removal rate of key pollutants The app will calculate the landscaping area PE OEE ETT needed to drain down the EEE aaa A necessary volume in the cisterns within five days allowing cisterns to capture runoff during the next storm event and will flag the user when there is not sufficient landscaping area In such case the user should consider increasing the landscaping area or using the water internally in the building To give a sense of the volume of water collected the app will also calculate the number of cisterns needed measuring 7 feet in diameter and 8 5 feet high Cisterns can be designed in many shapes and sizes in tanks or c
13. 0 91 E Landscape area no stormwater 4 Water quality capture volume required gal 24 573 feature 5 Green Infrastructure Outputs Square feet Gallons Captured E Above ground conventional facility 6 Landscape area no stormwater feature ee 7 Above ground conventional facility ee eee 8 Parking area next to building m Building Footprint w nogreen 9 Building Footprint w no green infrastructure infrastructure 10 Green roof E Green roof 11 Green roof water harvesting area 12 Rainwater harvesting area Ramaer eS oe 13 a m Biofittration 114 Rain gardens 145 Total green infrastructure water capture o 28 573 E Rain gardens 16 Conventional water quality facility ee Ce City of Austin Urban Design Division 9 Envision Tomorrow Green Infrastructure App Manual Entry If preferred the user may manually enter design specifications for the various stormwater controls in the fields to the left of the preset buttons Green roofs and rainwater harvesting systems are calculated according to the percentage of building footprint they cover The app will flag the user if the total of both exceeds 100 of the building footprint Biofiltration and rain gardens are limited to a percentage of the total landscaping entered on the Physical Inputs tab of the Prototype Builder If the total of both exceeds the allotted landscaped area the app will flag the user All green infrastructure controls have inputs for depth and efficiency of water an
14. 054 y Ll true USEPA national rate For more localized 0 001437 rates see GRID htt USEFA national rate For more localized 0 00525 rates see eGRID http USEFA national rate For more localized O 0000007 21 rates see eGRID http USEPA national rate For more localized D O00000266 rates see eGRID 191 Electricity Emmission rates NO2 Ibs KWh 192 Electricity Emmission rates 02 Ibs KWh 193 Natural Gas Emmission rates NO2 Ibs BTU 194 Natural Gas Emmission rates 02 Ibs BTU 195 US Forest Service NO2 5 lb Recommendations 196 US Forest Service 03 5 Ib Recommendations 197 US Forest Service 02 5 Ilb Recommendations US Forest Service PM 10 5 Ib 198 Recommendations 199 Green Infrastructure Climate Change Inputs Ave amount of carbon sequestered by plants General study for 200 Ibs SF 0 0332 http www cnt org species in midwest USEPA national rate For more localized 1 32935 rates see eGRID USEPA national rate For more localized O 0008229 rates see eGRID 201 Electricity Emmission rate COZ IbsiCo2tk wh 202 Matural Gas Emmission rate CO lbsiCo2 BTI EU Emissions Trading System Price of CO ilb 203 lower bound 204 205 City of Austin Urban Design Division 21 Envision Tomorrow Green Infrastructure App Outputs All outputs of the Green Infrastructure App in the Scenario Builder can be found on the Summary New tab The annual indicators calculate totals and p
15. Cistern Harvesting 142 Biofiltration 143 Rain gardens 1440 Water Harvesting 145 Sed S and Filter Changing the Stormwater Control Costs The defa u It sto rmwater co ntrol costs are based 59 Stormwater amp Green Infrastructure Cost per Gallon eum Gteeniool eee Fe total on a literature review See the hyperlinks g Bisitan de cue 0 0 S282 total f 62 Frain gardens dO 58 643 total below the cost section and the accompanying g3 Rainwaterharvesting OO f ttl 64 Conventional abowe ground total text boxes fo r m o re i nfo rm ati O n M O re loca ly ee ee ee eae qeneueaan new EA aaa ATAA T A ea i aaa a e EE OEA E E i 2 ee l AT e E a S et appropriate values may be input into the Be total cost Stormwater amp Green Infrastructure Cost per Gallon table rows 59 67 City of Austin Urban Design Division 18 Green Infrastructure App in the Scenario Builder Overview The Green Infrastructure App uses the information calculated in the Prototype Builder to measure the effects of water quality controls across scenarios In particular the benefits of green infrastructure controls selected in building prototypes are quantified using the methodology recommended by the Center for Neighborhood Technology CNT in its publication The Value of Green Infrastructure Additionally the app also creates a stormwater facility profile for each scenario modeled indicating how stormwater from a water qua
16. Gl_ Recharge Zone yes 1 8 GI_ Impervious __ Cover 0 6 0 5 GI_Impervious_Cover 0 2 Update the runoff coefficient cells to Runott Coer icient reflect impervious cover runoff coefficient curves You may need to do a curve fit to create the formula If using two tiers input your special district by adjusting the coefficients and operators highlighted below F B29 A200 IF 0 05 0 9 GI_Impervious_Cover lt 0 2 0 2 0 05 0 9 GI_ Impervious Cover IF Gl_Recha rge_Zone yes 0 6072 GI_ mpervious_Cover42 0 2899 GI_ mpervious_Cover 0 0075 0 5463 GI_ m pervious _Cover 2 0 328 GI_ Impervious Cover 0 0296 Input the rest of standards as highlighted below Note If not using a second tier enter the same coefficients and operators in the section highlighted above F B29 A200 1F 0 05 0 9 GI_Impervious_Cover lt 0 2 0 2 0 05 0 9 GI_ Impervious Cover IF Gl_Recha rge_Zone yes 0 6072 GI_Impervious_Cover42 0 2899 GI_Impervious_Cover 0 0075 0 5463 GI_Im pervious_Cove r 2 0 328 G _Impervious_Cove r 0 0296 City of Austin Urban Design Division 17 Envision Tomorrow Green Infrastructure App Prototype Builder Changing the Local Pollution Concentrations amp Removal Efficiencies To adjust pollutant load concentrations for your area change values in the Lookup Tables rows 113 136 under columns associated with Local numbers re ee oe Loo ET PTs J on mae Total Saspeaded Solids mgri Gauildiag Land
17. SBNVISION 2 COMOorrowW H Green Infrastructure App City of Austin Urban Design Division February 2014 ENVISION COMOlOW Green Infrastructure App Table of Contents WTAE OCI C1 NO Neenee es cauieresevsvvaynnsiseces nada ug nants eed oaesnnouundasaaa we eased aed rentonri sos eio eee eet 2 Green Infrastructure App QUICK Start Guide 20 ceeeccccsssseeceeceeseececceeseeceecseseeceeseuaaseceesseaseceesueuseeeesuanseeessuaaeeeessaansess 3 Green Infrastructure App in the Prototype Builder cccccccccccsssseccecceseccesseesececeaensecceseeaseceeseeaecessaenseceesauaeeessaganees 5 SEO FY AEST NOE a pease E oauissdican scat a EEE T E 5 Stormwater Contro lS cemiterio EE ee ee 6 RR OO ise cates E E E EE ET E T A 6 Green Roof Connected to Rainwater Harvesting System cccccsssssecccccessececeeeesecceeeaeeceesseeeceessueaeeeesseeaeseessaees 6 EEE EIE E A EE E A E A E E A PE E E E E 7 Biofiltration Systems cao cuganenjeese vse encesdaanssecas eas cueeaevaces so eedueoesaueuseamenasysqentargan bn auesansateesaamsauceneusudeneundestqamearscneaceress 7 FAN A NSS AE E E E EE E E EA E ueiu aaean E E 8 OV Ci Oe F a N ee EE E E EEEE EEE NE 8 POSOL BUNTON meren E E E O E 9 PING EEN UB S U ea E EE E suited aeedsecsatiiniver eon 9 Minim m Green Infrastructure sasurasane E EEE EEA E a 9 Green Infrastructure Medley sptececeetncensav sac cceuseqensentscansautacentesovaeeedeyeqandantaceactuecoensaeoncseseetanensantvarenceisquntantansat
18. Urban Design Division adis B rh l m Te ba Aa P at AN g ns as ns seneo 5 22 Envision Tomorrow Green Infrastructure App Scenario Builder Additional charts can be created from the calculated values found in the following Summary New tables CNT Annual Indicators of Green Infrastructure Benefits Runoff Reduction gal yr Energy Savings k wiyr Energy Savings fyr Air Pollutant Reduction Ibsfyr Value of Pollutant Reduction fyr i i CO2 Reductions Ibstyr 108 874 Climate Benefit Value of CO2 Reductions i i 823 Green Roof acres Biofiltration acres Conventional Facility water Quality Capture Green Infrastructure water Quality Capture Additional Green Infrastructure Capture Remaining Volume Requiring Treatment Turbidity Indicator Total Suspended Solids FR Nutrient Indicator Nitrogen Reduction Ibs Contaminant Indicator Lead Reduction Ibs Bacteria Indicator f Coli Reduction 1 000 col To view CNT annual indicators by an individual scenario as it is painted see the corresponding scenario tab t City of Austin Urban Design Division 23 Envision Tomorrow Green Infrastructure App Scenario Builder Many thanks to Donald Jackson for researching and assisting with this project Thanks also for assistance from the City of Austin Watershed Protection Department in particular from Matt Hollon For questions and suggestions
19. al No water quality controls amp No fee in lieu and aesthetic benefits e No water quality controls amp No fee in lieu will ignore any water quality needs for the building prototype by setting Fee in lieu to yes and setting the fee amount to SO 3 Customize design parameters of stormwater controls if needed If you know the specific design Percent of building footprint used for Rainwater Harvesting not inluded in green roof rainwater ee 44 Rainwater harvesting depth 0 10 F Beal Ranwa haves cies of Footprint for Water Harvest Dinca a Cell highlighted when the total green roof ps 46 Rainwater harvesting of pal and water harvesting percentages exceed 47 equivalent T x 6 5 cisterns 100 of the total building footprint 48 Landscaping area needed Percent of land caping ope 49 6 Biofiltration g0 Biofitration media depth 4 00 Fe enter percentage parameters of the controls you ve selected such as depth and efficiency you can customize them in the Physical D square feet Inputs section There are numerous pop up boxes that give more information enter percentage about specific defaults To activate them click on the adjoining text box City of Austin Urban Design Division 3 Envision Tomorrow Green Infrastructure Quick Start Guide Prototype Builder 4 Input annual rainfall under Pollutant Loads In order to get an accu
20. and a growing medium Their designs vary often ed resembling a smaller model of a biofiltration system or a short bioswale Rain gardens are often preferred for their flexibility and aesthetic potential in site design They are also often referred to or categorized as a bioretention systems in the stormwater literature but are listed as a separate control in the Building Prototype a a Rain garden at One Texas Center Austin Texas SUBGRADE City of Austin Environemental Criteria Manual 1 6 7 H 3 Conventional Facility The app assumes that if no green infrastructure facilities are selected the required water quality volumes will be treated with a conventional facility such as a sedimentation sand filter assuming fee in lieu is not selected Sedimentation sand filters are commonly used in Austin Texas and generally employ a sedimentation chamber and a sand filtration basin which uses a thick layer of fine grain sand on top of gravel to filter pollutants out of stormwater http www esf edu ere endreny GICalculator SandFilterl r v yyy ntro html Yay Wy An underground filter is used in physically restrained yey areas and can include a large storage vault where stormwater is stored while filtering through the system Though it is an effective system it has lower retention and pollutant removal capabilities than many green infrastructure systems and does not offer secondary cl benefit th logical i ii
21. and has many advantages over conventional grey systems It generally removes more pollutants than conventional controls and often allows for water infiltration into the soil more closely resembling natural patterns With greater infiltration the base flows of streams erosion and riparian health are less likely to be negatively impacted by increases in impervious cover associated with development Green infrastructure such as green roofs biofiltration and rain gardens are also generally more aesthetically appealing than the concrete basins frequently used in conventional controls Other numerous benefits included decreased energy costs improved air quality reduced heat island effect reduced carbon dioxide emissions and potential open space and habitat Because the water captured by cisterns is typically used to irrigate landscaped areas or for other onsite water needs rainwater harvesting is also considered green infrastructure This guide will first provide quick start instructions for using the Green Infrastructure App in the Prototype Builder followed by more detailed descriptions of both the Prototype Builder and the Scenario Builder components of the Green Infrastructure App including customization for local standards and conditions Conventional water quality control Green infrastructure Rain garden City of Austin Urban Design Division 2 Green Infrastructure App Quick Start Guide 1 Select the appropriate stormwater mo
22. anning and Management Island Press Rowe Bradley 2010 Green roofs as a means of pollution abatement Environmental Pollution Volume 159 Issue 8 9 http www sciencedirect com science article pii SO269749110004859 Rusciano and Opropta 2007 Bioretention column study fecal coliform and total suspended solids reductions American Society of Agricultural and Biological Engineers http www prairieswine com pdf 3049 pdf Stormwater Manager s Resource Center The simple method to calculate urban stormwater loads Center for Watershed Protection http www stormwatercenter net monitoring 20and 20assessment simple 20meth simple htm Stormwater Manager s Resource Center Water quality sizing Center for Watershed Protection http www stormwatercenter net Manual Builder Sizing Criteria Water 20quality Options 20for 20Water 20Quality 20 Volumes htm University of Florida IFAS Extension 2008 Florida field guide to low impact development Biorentention Basins Rain Gardens http buildgreen ufl edu Fact sheet Bioretention Basins Rain Gardens pdf US Environmental Protection Agency Clean Energy eGRIDweb _http cfoub epa gov egridweb US Environmental Protection Agency September 1999 Storm water technology fact sheet sand filters http water epa gov scitech wastetech upload 2002 06 28 mtb _ sandfltr pdf US Environmental Protection Agency September 1999 Storm water technology fact sheet bioretention http water epa gov scitech was
23. atter in each control with the amount air pollutant emissions avoided because of energy savings and associated decrease in power generation The Criteria pollutants addressed are nitrogen dioxide NO2 ozone O3 sulfur dioxide SO2 and particulate matter PM 10 Annual CO2 reductions is calculated by adding the amount of carbon sequestered by vegetative matter in each control with the amount of avoided CO2 emissions due to energy savings and the associated decrease in power generation Reductions in CO2 reductions translate to reduced impacts to global climate change Potential Open Space and Habitat is calculated by delineating the acreage of biofiltration and green roofs Open space can be defined in many ways and not all green infrastructure controls will meet open space requirements defined in local standards For example an extensive green roof is not intended to be occupied Habitat for local fauna can be enhanced when green infrastructure controls are planted with native species Of the types of green infrastructure considered in the app green roofs will contribute to all five indicators because of their insulating effect and the resulting reductions in energy use and associated pollutants They are also generally the most expensive type of green infrastructure but may provide a reasonable choice particularly in confined areas given the many ecological and social benefits they can provide The Green Infrastructure app will also ag
24. d lower associated treatment costs fewer pollutants entering waterways and improved soil infiltration which can improve base stream flows improve riparian health reduce erosion and improve groundwater recharge Note The CNT guide recommends monetizing this value by using the avoided stormwater treatment costs however in areas where a combined stormwater sewer systems is not used this cost does not apply Identifying the cost of avoided public stormwater infrastructure may be an area for future exploration Annual energy savings is calculated by multiplying the reduction in energy use due to the insulating effect of green roofs with the cost for energy The insulating effect of green roofs is determined from the annual number of cooling heating degree days and the difference in the heat transfer coefficient between a conventional roof and a green roof The insulating effect of green roofs can reduce both heating and cooling costs as well as reduce the heat island effect found in urban areas by lowering the ambient temperature beyond the green roof environs A reduction in the heat island effect also reduces the likelihood of ozone formation directly impacting air quality This effect however is not measured by the app City of Austin Urban Design Division 19 Envision Tomorrow Green Infrastructure App Scenario Builder Annual air pollutant reductions is calculated by adding the amount of criteria air pollutants absorbed by vegetative m
25. del Green Infrastructure amp Stormwater Inputs Select National simple method on the Green 2g Stormwater Model National Infrastructure tab of the Prototype Builder unless the og Select model 30 app has been customized to your local conditions e ee eas Currently customized to Austin TX 2 2 Click on the appropriate preset button e No green infrastructure assumes conventional controls will ait Green Infrastructure Presets be used to treat the minimum volume of stormwater required to be captured No Green e Minimum Green Infrastructure will automatically select Infrastructure green infrastructure controls depending on the site configuration in the Prototype Builder in order to satisfy the minimum water quality capture volumes If there is enough landscaping area set aside rain gardens will be selected Minimum Green followed by biofiltration rainwater harvesting and finally Infrastructure green roofs connected to a cistern when there is not enough landscaping to accommodate other less expensive controls Green infrastructure controls will generally provide more environmental and aesthetic benefits Green Infrastructure e Green Infrastructure Medley will assign a mix of rain gardens Medley rainwater harvesting and green roofs attached to a cistern This setting will generally exceed the minimum required volume of stormwater with the accompanying environment
26. down times may not apply Check local standards for more information Green roof area needed for harvested water sf Green roof water harvesting Gallons Captured 7 48 gal cu ft 0 005 ft hr soil conductivity 120 hours drain down time 12 hours lag time Landscaping area needed for harvested water sf Rainwater harvesting Gallons Captured 7 48 gal cu ft 0 005 ft hr soil conductivity 120 hours drain down time 12 hours lag time Pollutant loads are calculated according to land uses selected on the Physical Inputs tab and square footage calculations found on the Physical Outputs tab for building footprint landscaping and parking areas Pollutant concentration levels on the lookup tables are derived from national or local studies Local values are currently calibrated for Austin Texas but can be adjusted to reflect other local studies Annual Runoff National simple method in Annual Rainfall in of annual rainfall producing runoff 90 default Runoff Coefficient Annual Runoff Local Austin in Annual Rainfall in Runoff Coefficient Annual load TSS TN and TL bs 0 226 Annual Runoff in Pollutant Concentration according to lookup table mg l Applicable Area sf 43 560 sf acre Annual load F Coli billions of colonies 103 Annual Runoff in Pollutant Concentration according to lookup table mg l Applicable Area sf 43 560 sf acre Pollutant removal calculations refer to control treatment
27. efficiency of a conventional facility and if the facility is underground This will impact the cost of the facility and the overall project cost since underground facilities are more expensive than surface controls Please note if no green infrastructure controls are selected by inputting a corresponding percentage of building footprint and or landscaped area the app will automatically assume that a conventional control will meet necessary water quality volumes and will size it appropriately according to that volume Likewise if the size of green infrastructure controls is not sufficient to meet required water volumes the remaining volumes will be assumed to be handled by an appropriately sized conventional control The app will flag the user when a City of Austin Urban Design Division Envision Tomorrow Green Infrastructure App Prototype Builder conventional control is used To view the volume of water handled by each selected control refer to the dashboard at the top of the tab under Green Infrastructure Outputs Click on the first expansion button on the left if needed to view these cells Stormwater and Green Infrastructure Costs The utility also calculates the cost of each system based on a price per gallon function and incorporates the cost into the overall project costs calculated by the Prototype Builder These prices were determined through a literature review links to which are listed at the bottom of this secti
28. en roofs to a rainwater harvesting system Green roofs efficiencies generally improve when connected to a cistern City of Austin best practices recommend a green roof tied to a cistern which can capture a much higher portion of stormwater approximately 65 total compared to just 20 with the green roof alone Since cisterns generally must be emptied or sufficiently depleted in between storm events in order to be available for the next storm event the water collected typically irrigates landscaped areas or is used internally in the building as greywater The app will estimate the square footage of a landscaped area needed in order for the cisterns to drain down within 120 hours after a storm event assuming no water is released from the cistern for the first 12 hours after a storm event This calculation assumes a soil hydraulic connectivity of 0 005 feet per hour This value may differ for different soil types and is intended only as a general indicator If the areas are not sufficiently large for the volume of water collected to drain down within 120 hours the app will flag the user Please note that if more than the required minimum volume of water is being collected the drain down requirement may not apply and water may potentially be stored for longer term irrigation of landscaped areas Please refer to local standards for more information on drain down times and requirements Finally the user may also indicate the capture
29. eneeas 9 No water quality controls amp No fee in lieu eesssssssseeessssereesssreresssrerssssrrrssssrrrsssreresssrerosserressserresssreressereresseeee 9 Manaa ETI oa E E E E EE 10 Stormwater and Green Inirastruct re COSES sersrrroraoeire rinne nnne aaa EEE AEE EAEE 11 POUNER E ON e E E E E E T E EAS 12 Key PolUtaN Seians E NE E EE E 12 DTE ee E AE A E E E T E E E AT 12 OS CACAO ee E E E E E E G 13 Appendix A Green Infrastructure App Prototype Builder Formulas ccccccccsssseccecceeseccceeeeeeeeessaeeeeessaeeeeeeees 15 Appendix B Prototype Builder Local CUStOMIZAtTION ccccccsssccccssececceneecceeseccssuscesseeeesaueessauecessaeeeesaaeseeseneeess 17 Changing the Local Stormwater Model sccutsisaavadennennssyvceooadsid snedadeciiennedsaontievideadeaitnoondaa dnnoadsismnoen vansaeesivnnoetoeieanas teal 17 Changing the Local Pollution Concentrations amp Removal EffiCci NCieS cccccseeccccssececeeecceeeseceeeeseceeaeeceeseneeess 18 Changing the Stormwater Control Costs ccsccccccssssecccceessccccceesseececseeaseccesaeaseceesseeeeceeseaeeeeesseaaecessaueeeessages 18 Green Infrastructure App in the Scenario Builder cccccesccccccsssecccccesseccecceeseccecasaeaeeecssseaseeeesauaeeceesaanecessageeeesseees 19 COVE VIC WW orep onn a ETE negevaieaessanetctaeraauennsaunvangoauatGeqehaatiausreaieoap nun A EE EE 19 ATEND a no AAS E A A E E E E A A E E E A A A A O E A A E EO E A 21 UATE ME E A E E E
30. er acre values across scenarios according to the formulas found in the CNT The Value of Green Infrastructure guide Five charts graph several of these values across scenarios e Runoff reduction gal yr e Energy savings kW yr most associated with green roofs e Air pollutant reductions lbs yr most associated with green roofs e CO2 reductions lbs yr most associated with green roofs e Potential open space amp habitat acres from green roofs and biofiltration including rain gardens The app also summarizes several values from the Prototype Builder that are aggregated across scenarios The Stormwater Facility Profile characterizes the method used to accommodate required water quality volumes through conventional facilities and green infrastructure as well as required volumes that are not captured The chart also graphs additional capture beyond required volumes depicting possible opportunities to use additional capacity to meet water quality needs by hydrologically connecting sites or using district wide controls within the same scenario planning area The app also compares the percentage reduction of four key pollutants that act as indicators for e Turbidity total suspended solids TSS Affects water clarity and sedimentation e Nutrient loading total nitrogen TN Linked to algae blooms and other ecological problems e Contaminants total lead TL Harmful to human and health e Bacteria fecal colif
31. g Biofiltration Rain Gardens Sed Sand Filter U 1 Te TTE TTET 32 437 0 076 0 000 0 035 0 031 0 000 0 000 0 000 E andsa E a a a 2 178 0 009 0 000 0 007 0 000 104 i 0 034 0 000 0 027 0 000 0 000 Area st colonies 32 437 2233 2 178 12815 8 945 1008 City of Austin Urban Design Division 14 Envision Tomorrow Green Infrastructure App Prototype Builder Appendix A Green Infrastructure App Prototype Builder Formulas The following formulas guide the operation of the water volume and sizing functions of the app Variables listed in red text are inputs by the user Those in bold refer to other formulas defined in this document Italics indicate unit of measurement Impervious Cover Physical Outputs BuildingFootprint sf Physical Outputs Parking sf Physical Inputs SiteArea sf Water quality capture volumes can be calculated using numerous techniques The simple method used to estimate required volumes also called the 90 rainfall event method is based primarily on impervious cover More sophisticated methods consider the intensity of rainfall soil conditions and other factors If local stormwater capture requirements are based on impervious cover and runoff coefficients they can be used to customize the local formulas in the Green Infrastructure app See Appendix B for more details Water quality capture depth National simple method in Runoff Coefficient Design storm rainfall depth in Design storm rainfall dep
32. gregate selections made in the Prototype Builder across the selected planning area in the Scenario Builder The Stormwater Facility Profile identifies the method used for meeting water quality needs whether by green infrastructure conventional controls or through fee in lieu and if excess Capacity may be available to address unmet needs Sites with additional capacity and those with unmet needs would need to be hydrologically connected The profile is intended to give an initial snapshot of potential district wide water quality controls To review the calculations for water quality volumes please refer to app description in the Prototype Builder portion of this document The app also summarizes the percentage removal of four key pollutants across a scenario Please refer to the Pollutant Removal section in the Prototype Builder section of this document for more information on calculation of these values Each key pollutant indicates a type of pollutant total suspended solids TSS indicates turbidity total nitrogen TN indicates nutrient loading associated with algae blooms and other ecological problems total lead TL refers to contaminants general harmful to human and animal health and fecal coliform indicates bacteria associated with disease The overall performance for these four water quality indicators can be compared across scenarios City of Austin Urban Design Division 20 Envision Tomorrow Green Infrastructure App Scenario B
33. he percentage reduction of four key pollutants Key Pollutants The app focuses on four key pollutants that indicate four different types of substances that can impact ecological and human health 72 Pollutant Loads To Annual Rainfall 74 Of annual rainfall producing runoff To Total Sususpended Solids TSS reduction TG Total Nitrogen TN reduction Total ead Ey reacbon a eeen AE TG F Coli Reduction 79 Total key pollutants removed TSS TN TL lbsiyr Total Suspended Solids TSS measured in pounds are an indicator of the turbidity of the water and the potential sedimentation of waterways Many other pollutants are frequently attached to TSS and removing TSS will frequently remove other pollutants Total Nitrogen TN measured in pounds indicates the level of excessive nutrients associated with algae blooms and other ecological problems Total phosphorous is also a common nutrient found in excess but not measured by the app Total Lead TL measured in pounds is an indicator of contaminants found in stormwater that are harmful to human and animal health Levels of copper and zinc in stormwater are also frequently measured but not considered by the app Fecal Coliform measured in billions of colonies is also approximated by the app and is among several bacteria linked to disease Fecal streptococci is another bacteria sometimes measured to gauge stormwater quality but not considered by the app
34. isterns for use in landscaping irrigation horticultural irrigation or building greywater Rainwater harvesting has tremendous potential for reducing the amount of outdoor water used in landscaping It also serves the same function of capturing and treating stormwater flows as other Best Management Practices BMPs The defaults Rool Catchment Area Conveyance System Pump System for Irrigation Max 120 hr Drawdown Time Irrigation Area Profile SS Conveyance System Plan View City of Austin Environmental Criteria Manual 1 6 7 D 4 Biofiltration Systems Biofiltration systems also referred to as bioretention capture and filter stormwater oa r M gt _ oe Eee x Ai ty through vegetation and growing medium and are generally used for larger sites than rain gardens The sedimentation chamber and filtration basin are not unlike conventional systems but the addition of organic matter generally leads to more stormwater being treated than in sand h perbo filters which without the benefit of plant roots are prone to clogging PE http keepaustinbeautiful org KABAwards2011 City of Austin Urban Design Division Underdrain Piping net City of Austin Environmental Criteria Manual 1 6 7 C 1 Envision Tomorrow Green Infrastructure App Prototype Builder Rain Gardens Rain gardens are small bioretention systems designed to catch and hold stormwater that is filtered by vegetation
35. late required water quality volumes the simple method has proven to yield reliable ballpark figures and is appropriate for planning purposes The amount of runoff can vary depending on local soils and conditions If there is more localized information available on the amount of runoff expected as a function of impervious cover the app can be customized to reflect the local conditions Currently the local stormwater model appears as Local Austin and is calibrated to the City of Austin s Environmental Criteria Manual at the time of development of this app in 2013 For information on customizing the app please refer to Appendix B The sizing used in the simple method is also called the 90 Rainfall Event method called such because controls are sized to Design storm rainfall depth __1 00 in capture 90 of average annual stormwater runoff volume If the user chooses this stormwater model the user may adjust the design storm rainfall depth Generally between 1 and 1 5 inches it is the depth of stormwater that should be captured to account for 90 of the annual pollutant load The default is 1 inch For a list of values for 90 rainfall events for select US cities refer to the Center for Watershed Protection Stormwater Manager s Center City of Austin Urban Design Division 5 Envision Tomorrow Green Infrastructure App Prototype Builder If the local model is chosen the user has the opportunity to 28 Stormwater Model select from o
36. lity perspective is handled across the scenario planning area It will also aggregate the removal of four key water pollutants by stormwater controls across the scenarios The CNT guide outlines eight areas in which green infrastructure can provide benefits reduced runoff reduced energy use reduced air pollutants reduced atmospheric CO2 reduced urban heat island effect community livability habitat improvement and public education Not all of these areas are easily quantifiable in some cases due to as yet an insufficient body of research literature Of the areas identified in the CNT guide the Green Infrastructure App quantities five areas in the Scenario Builder according to CNT formulas reduced stormwater runoff reduced energy use reduced air pollutants reduced atmospheric CO2 and potential habitat acreage The values produced are intended as rough estimates and can be informative through the comparative nature of the Scenario Builder For the purposes of the CNT measures rain gardens and biofiltration controls used in the Prototype Builder are aggregated into one biofiltration category in the Scenario Builder Annual reduced runoff is calculated by multiplying annual rainfall the area of the green infrastructure control the drainage area in the case of the water harvesting and its retention efficiency It applies to all control types Reduced runoff can translate into reduced incidents of combined sewer stormwater overflows an
37. ne of two models assuming the app has been Local austin Local Austin correspondingly customized In the case of Austin Texas See eee water quality requirements are greater over the sensitive Runoff Coefficient Barton Springs Zone located above the porous karst Edwards Aquifer By selecting yes for this cell the Water quality capture volume required gal cell is correspondingly adjusted For more information on customizing the app to local formulas please refer to Appendix B Using the impervious cover calculated by Green Infrastructure Stats the Prototype Builder and the chosen 1 stormwater model the app will calculate 7 e e the required water quality capture 3 Water quality capture depth in 0 91 4 Water quality capture volume required gal 24 573 volume in the dashboard at the top of the tab Stormwater Controls The app allows the user to select from several green infrastructure controls to treat the required stormwater capture volumes green roofs green roofs connected to rainwater harvesting systems rainwater harvesting biofiltration and rain gardens If none are selected by inputting design features the app assumes treatment will be handled by a conventional system typically a sedimentation sand filter Green Roof Green roofs use vegetation and a growing medium instead of conventional roofing materials In CSS di addition to treating stormwater they offer many benefits
38. o cost per gallon and entered in this section of the app The app also offers the option to include additional fees under Mitigation fee Fee in lieu If water quality controls are used and a mitigation fee is required select no and enter the fee to the right If fee in lieu is used with no water quality controls to be constructed for the project select yes and input the amount in the adjacent cell If there is no consideration for water quality controls as is sometimes the case in infill situations then select yes and enter SO The same inputs may be set automatically by selecting the fourth preset button No water quality controls amp No fee in lieu City of Austin Urban Design Division 11 Envision Tomorrow Green Infrastructure App Prototype Builder Pollutant Removal Stormwater controls remove a wide array of pollutants and pollutant levels vary according to land use a single family home will have different pollutant levels from an industrial site Within a site pollutant levels will also vary with parking areas differing from landscaped and building roof areas The Green Infrastructure App estimates the amount of pollution expected given the land uses selected by the user on the Physical Inputs tab and the amount of land dedicated to building parking and landscaping as calculated by the Prototype Builder Based on the efficiencies of each type of stormwater control selected the app will then estimate t
39. ocuments 0 5949 2 pdf Minnesota Pollution Control Agency 8 November 2013 Minnesota Stormwater Manual Requirements recommendation and information using green roofs as a BMP in the MIDS calculator http stormwater pca state mn us index php Requirements recommendations and information for using green roofs as Narayana Arvind and Pitt Robert June 18 2006 Costs of Urban Stormwater Control Practices http www water ca gov irwm grants docs Archives Prop84 Submitted Applications P84 Round1 Implementation San 20 Diego 20County 20Water 20Authority Bannock 20Ave Tecolote 20Watershed 20Protection Arvind and Pitt_stormwat er cost report pdf New York State Department of Environmental Conservation New York State Stormwater Management Design Manual Appendix A The Simple Method to Calculate Urban Stormwater Loads http www dec ny gov docs water_ pdf simple pdf New York State Department of Environmental Conservation New York State Stormwater Management Design Manual Chapter 4 Unified Stormwater Sizing Criteria http www dec ny gov docs water_pdf chapter4p18 pdf Prince George s County Maryland Environmental Services Division Department of Environmental Resources December 2007 Bioretention Manual http www aacounty org DPW Highways Resources Raingarden RG Bioretention PG 20CO pdf City of Austin Urban Design Division 25 Envision Tomorrow Green Infrastructure App Scenario Builder Randolph John 2004 Environmental Land Use Pl
40. on For more information on particular costs click on the accompanying text cell to view a pop up box 59 Stormwater amp Green Infrastructure Cost per Gallon 60 Green roof 61 Biotitration I total 62 Rain gardens 63 Rainwater harvesting 64 Conventional above ground 65 Conventional underground ll an Dera E E a 66 Mitigation fee Fee in leu onh 67 Total cost total total total total total enter amount 110 578 Default green infrastructure costs are based on the study The Costs of LID Low impact development BMP installation and operation and maintenance costs in Orange County CA which lists costs at 2011 values Please note that the current default for green roofs is for an extensive roof i e non occupiable Intensive green roofs occupiable roofs will vary from 46 to 64 per gallon treated according to the same study Default costs for convention controls sedimentation sand filters are based on the study The Costs of Urban Stormwater Control Practices and have been adjusted to 2011 values Default cost for underground controls sedimentation sand filters where more difficult to determine and are based on interpolating costs adjusted to 2011 values provided in both The Costs of Urban Stormwater Control Practices and Sand and Organic Filters In all cases if local construction costs for stormwater controls are available they should be normalized t
41. orm f coli Linked to disease Scenario Builder Runoff Reduction from Green infrastructure E Bua Scenario i Tenio 3 Soerarig d Sterner l E Rait durt gan yh Energy Savings from Green Infrastructura z cor Boog xou i non Seeriarla I Senani 1 kerana J Seenan 4 r Leary dosing fey eel Air Pollutant Reduction from Green Infrastructure izt LI bana enata 1 engm 2 eneio Y Pernai 4 2 Mi Forse bo aye CO2 Reductions from Green Infrastructure bad oe op So E io 2555 aw d L E A Sconaran Scena i cenario inip i S001 Ar Potential Open Space amp Habitat from Green Infrastructure Scenario l canai j Senario i Scenaria 4 MGShaha liso Daaa Rood an Stormwater Facility Profile Char Are Senario 4 keimai keriari J kenara J Dent ora aen Aar y Spt Grids kijuu Wita Dakia ea ey ee ee TH E eraria 5 kerari 5 Terai 5 icenac 5 E Rue 4 nk 4 Gut Lote 4 n 2 e Soenark 3 keiric i s 1842 atl Giidi te Pato n a SS 5 Water Quality Pollutant Load Reductions TILLILLLIF Senso 3 Scenario 4 Tart ly hOcow Tap baem bed Seb ds Reduction Br a Nut ere beduster Met age Rodat er ee enano l Scenario 2 Siomin Eny sem Sed cto ey Baneve ino ame H Cot Aegumen i OO esas Please see the section on key pollutants in this document for more information City of Austin
42. r harvesting Gallons Captured Rainwater harvesting of building footprint Physical Outputs BuildingFootprint sf Physical Outputs Parking sf if selected Rainwater harvesting depth ft Rainwater harvesting efficiency 7 48 gal cu ft Biofiltration Gallons Captured Biofiltration of landscaping area Physical Outputs Landscaping sf Biofiltration media depth ft Biofiltration capture efficiency 7 48 gal cu ft Rain gardens Gallons Captured Rain garden of landscaping area Physical Outputs Landscaping sf Rain garden depth ft Rain garden capture efficiency 7 48 gal cu ft Conventional water quality facility Square Feet Remaining required water quality volume gal 7 48 gal cu ft 4 ft depth Conventional facility capture efficiency City of Austin Urban Design Division 15 Envision Tomorrow Green Infrastructure App Prototype Builder Irrigation areas needed for harvested water depend on required drain down times for cisterns in order to make them available for the next storm event The app assumes that the required drain down time is 120 hours and that draining of cisterns begins 12 hours after the storm event Soil conductivity will vary for different soils but is assumed to be 0 005 feet per hour in the app Drain down times and soil conductivity can be adjusted in the cell formula to reflect local conditions If a storage cistern is provided or water is harvested beyond the required minimum required drain
43. rate reflection of the amount of pollutants removed particularly when aggregating building prototypes across scenarios in the Scenario Builder enter the amount of annual rainfall in inches 7 Pollutant Loads To Annual Rainfall 76 Total Nitrogen TN reduction ff Total Lead TL reduction TS F Coli Reduction 32 5 in 74 o of annual rainfall producing runoff To Total Sususpended Solids TSS reduction 0 enter percentage 79 Total key pollutants removed TSS TN TL btu 5 Review stormwater dashboard 1 2 B E D E 1 Green Infrastructure Stats Site Layout with Stormwater Features 2 Impervious Cover 95 3 Water quality capture depth in 0 91 a area no stormwater 4 Water quality capture volume required gal 24 573 P aj R conventional facility 5 Green Infrastructure Outputs square feet Gallons Captured 4s Total green infrastructure water capture 24873 ee 16 Conventional water quality facitty m Building Footprint w nogreen 17 Financial Stats infrastructure m Green roof 48 Rental Residential and Commercial Target Return Actual Return 19 Cash on Cash After Year 3 P woo Rainwater harvesting area 0 20 IRR on Project Cost UnleveragedReturn 420 42 2 aa 24 Owner Residential EA 25 Project Rate of Return 250 MA m Rain gardens 26 Return to Equity At the top of the Green my B c 1 Green Infrastructure Stats Infrastructure tab you can 2 OEE 95 re
44. regarding the Green Infrastructure App or this document please contact Sylvia Leon Guerrero Senior Planner URBAN DESIGN City of Austin Planning and Development Review Department 505 Barton Springs Road 8 floor Austin TX 78704 Email Sylvia LeonGuerrero Qaustintexas gov City of Austin Urban Design Division 24 Envision Tomorrow Green Infrastructure App Scenario Builder References Alsup et al April 2013 Green roof systems as sources or sinks influending heavy metal concentrations in runoff Journal of environmental Engineering http ascelibrary org doi abs 10 1061 ASCE EE 1943 7870 0000601 Berndtsson Justyna Czemiel April 2010 Green roof performance towards management of runoff water quantity and quality A review Ecological Engineering http www sciencedirect com science article pii S0925857410000029 Center for Neighborhood Technology 2010 The Value of Green Infrastructure http www cnt org repository gi values guide pdf City of Austin Environmental Criteria Manual Section 1 6 http austintech amlegal com nxt gateway dll Texas environ section1 waterqualitymanagement f templatesSfn default htmS3 0Svid amlegal austin environmentSanc JD 1 6 9 3 Clary Jane et al May June 2008 Can Stormwater BMPs remove bacteria New finding f from the international stormwater BMPS database Stormwater Magazine http www udfcd org downloads pdf tech_ papers Can 20Stormwater 20BMPs 20Remove 20Bacteria pdf
45. s that can also be adapted to reflect other two tiered standards Because of the sensitive karst aquifer in the area the Edwards Aquifer the city has more stringent requirements for areas in the Barton Springs Zone which are hydrologically connected to the aquifer 1 Change the local reference Go to cell A199 These rows may need to Menu Data Do Not Alter oo amp yes be unhidden Changing the cell contents from Local Austin to your Wee no local reference will reflect throughout the app 199 _ Local Austin 200 National simple method an Located in Barton Springs zone ne not have a two tiered system conditional formatting is suggested to hide these cells Update the local special zone by going to cell A30 and modifying the text If you do Update the water quality depth cells to 3 Water quality capture depth in 0 91 reflect local requirements Go to cell C3 and change the formula to reflect local standards If using two tiers input your special district by adjusting the coefficients and operators highlighted below F B29 A200 GI_Runoff_Coefficient GI_rainfall_depth IF GI_Recharge_Zone yes 1 8 GI_Impervious_ Cover 0 6 0 5 GI_Impervious_Cover 0 2 Input the rest of the standards as highlighted below Note If not using a second tier enter the same coefficients and operators in the section highlighted above IF B29 A200 GI_Runoff_Coefficient GI_ rainfall depth IF
46. scaping Parkis Type simple method i simple method i simple method Residential Commercial Industrial Total Hitrogta mgt Type simple method i simple method Residential Commercial Industrial Lead Pb mgl Type simple method i simple method Residential Commercial Industrial F Coli 1 000 colosiesiel Typs simple method i i simple method Residential Commercial Industrial The default values for the effectiveness of various control types in removing pollutants are based on a survey of academic and professional literature as well as City of Austin standards Some treatment efficiencies vary widely according to the type of growing media used and the design of the control particularly for green roofs Because of the wide variation the default efficiencies for green roofs and green roofs connected to cisterns are set to City of Austin suggested practices in which green roofs are connected to cisterns and collected water is then circulated back onto the green roof resulting in a removal efficiency of 100 For more information on specific efficiencies click on the appropriate cell in the Treatment Efficiencies table to activate the hyperlinks to the source material or hover over the associated text to view comment boxes If more locally appropriate values are available they may be input into the Treatment Efficiencies table 129 Treatment Efficiencies 140 Green Rook 141 Green Root with
47. so uses other site information calculated or input into the Prototype Builder to determine anticipated pollution levels and the effectiveness of the water quality controls selected to remove those pollutants The water quality controls available in the Green Infrastructure App are green roofs green roofs with attached cisterns rainwater harvesting biofiltration systems rain gardens and a conventional water quality control a sedimentation sand filter The costs for selected water quality controls are then incorporated into the overall cost of the building as calculated by the Prototype Builder Stormwater Model To use the app the user must first select the appropriate stormwater model a standardized national model that uses the simple method also called the 90 rainfall event or a more localized model 22 Stormwater Model 79 Select model National simple method 34 Design storm rainfall depth gt 327 Runoff Coefficient There are a number of ways to determine the volume of stormwater that should be captured to remove the majority of pollutants from the first flush of a storm event The green infrastructure app allows the user to choose from two stormwater models the simple method listed as National simple method or a local customized version Both are calculated from the amount of impervious cover as determined by the Prototype Builder While there are more sophisticated and precise methods to calcu
48. tetech upload 2002 06 28 mtb _biortn pdf US Environmental Protection Agency National Pollutant Discharge Elimination System July 2012 Sand and Organic Filters http cfoub epa gov npdes stormwater menuofbmps index cfm action browse amp Rbutton detail amp bmp 73 US Environmental Protection Agency 2012 Stormwater Management http www epa gov oaintrnt stormwater index htm US Federal Highway Administration Stormwater best management practices in an ultra urban setting selection and monitoring fact sheet surface sand filters http environment fhwa dot gov ecosystems ultraurb 3fs8 asp US National Climatic Data Center Heating amp cooling degree day data National Oceanic and Atmospheric Administration http www ncdc noaa gov oa documentlibrary hcs hcs html US Energy Information Administration April 2010 Annual Energy Outlook 2010 with projections to 2035 http www eia gov oiaf aeo pdf 0383 2010 pdf City of Austin Urban Design Division 26
49. th default 1 in For values for select US cities see the EPA Stormwater Manager s Center Water quality capture depth Local Austin in 0 5 Impervious Cover 0 2 Water quality capture depth Local Austin Barton Springs Zone in 1 8 Impervious Cover 0 6 Water quality capture volume required gal Water quality capture depth in 12 in ft Physical Inputs SiteArea sf 7 48 gal cu ft Runoff coefficient formulas typically are curve fits of runoff coefficients plotted against impervious cover for a particular area Curves will vary according to the soils and conditions receiving runoff Currently the app is locally calibrated to Austin values but can be customized to reflect other local conditions Runoff Coefficient National simple method 0 05 0 9 Impervious Cover NOTE Minimum 0 2 Runoff Coefficient Local Austin 0 5463 Impervious Cover 0 328 Impervious Cover 0 0296 Runoff Coefficient Local Austin Barton Springs Zone 0 6072 Impervious Cover 0 2899 Impervious Cover 0 0075 Green roof Gallons Captured Green roof of building footprint Physical Outputs BuildingFootprint sf Green roof media depth ft Green roof capture efficiency 7 48 gal cu ft Green roof water harvesting Gallons Captured Green roof of building footprint Physical Outputs BuildingFootprint sf Green roof harvesting depth ft Green roof harvesting efficiency 7 48 gal cu ft Rainwate
50. uilder Inputs All of the inputs for the Green Infrastructure indicators can be found on the Project Info tab Many of the defaults are found in the Center for Neighborhood Technology guide The Value of Green Infrastructure In some cases a national reference value is listed with a corresponding hyperlink available for look up of more regional applicable values 177 Green Infrastructure Water Inputs 178 Average annual rainfall in 179 Green Infrastructure Energy Inputs 130 Annual Cooling degree days cde noaa cov oa documentlibrary hes hes html 181 Annual Heating degree days 182 R conventional SF Fhrs BTU 183 R green roof SF F hrs Btu ncdc noaa cov oa documentlibra US EIA 2010 national 184 Cost per kWh electricity cooling 5 kWh 0 0959 rate eia cov oiaf aeo pdf 0383 2010 pdf US EIA 2010 national 185 Cost per BUT natural gas heating 5 Btu 0 0959 rate eia 2ov oiat aeo pdt 0383 2010 pdt 186 Green Infrastructure Air Quality Inputs 187 Avg Annual NO2 uptake depositions Ibs SF 185 Ave Annual 03 uptake depositions Ibs SF 189 Avg Annual 02 uptake depositions Ibs SF 190 Avg Annual PM 10 uptake depositions Ibs SF flink springer com article 10 100792Fs11252 008 0054 y Ll true flink springer com article 10 1007962Fs11252 008 005 4 y Ll true i flink springer com article 10 1007 962Fs11252 008 0054 y Ll true flink springer com article 10 1007962 Fs11252 008 0
51. view the various outputs of 3 e ee 4 Water quality capture volume required gal 24 573 your selections such as the 5 Green Infrastructure Outputs 6 Landscape area no stormwater feature square footage of each control Fa Above ground conventional facility selected and the volume of water 8 aS a l E Building Footprint wino green infrastructure treated by clicking the first 10 Green roof 4 Green roof water harvesting area sign 12 Rainwater harvesting area gt 13 Biofittration 14 Rain gardens 2 053 15 Total green infrastructure water capture 24573 16 Conventional water quality faciity oo City of Austin Urban Design Division Green Infrastructure App in the Prototype Builder The Envision Tomorrow Prototype Builder is essentially a pro forma allowing the user to build a project quantitatively and investigate the physical and financial aspects of a new building The user enters physical characteristics such as site size number of stories parking requirements use and setbacks as well as financial information such as acquisition and construction costs and expected revenues from rent or sale From these inputs the Prototype Builder calculates a wide array of values from building footprint to return on investment The Green Infrastructure App uses the impervious cover calculated by the Prototype Builder to determine the volume of stormwater typically required to be captured for treatment for a given site It al
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