1. Civil & Environmental Consultants, Inc. Water Quality Management Program Staff Training

2. Civil & Environmental Consultants, Inc. Why is this change necessary?Why is this change necessary? Program rationaleProgram rationale Describe new BMPsDescribe new BMPs Plans review processPlans review process Operation and Maintenance PlanOperation and Maintenance Plan Design examplesDesign examples Agenda

3. Civil & Environmental Consultants, Inc. 6 Minimum Control Measures6 Minimum Control Measures Post construction storm water quality treatmentPost construction storm water quality treatment “…treat storm water to the maximum extent practicable…”“…treat storm water to the maximum extent practicable…” All new developments and redevelopments disturbing 1+ acresAll new developments and redevelopments disturbing 1+ acres NPDES Phase 2 regulations:

4. Civil & Environmental Consultants, Inc. Steps Taken to Date: Ordinance with post construction languageOrdinance with post construction language BMP storm water stakeholder groupBMP storm water stakeholder group BMP Manual revisedBMP Manual revised Ordinance revisedOrdinance revised Developed plan review and permitting processesDeveloped plan review and permitting processes TrainingTraining

5. Civil & Environmental Consultants, Inc. Schedule Effective date = March 31Effective date = March 31 If plan has been platted and has approved SWMP, no additional storm water quality treatment required.If plan has been platted and has approved SWMP, no additional storm water quality treatment required.

6. Civil & Environmental Consultants, Inc. About the program…

7. Civil & Environmental Consultants, Inc. Program rationale Step 1: Define “Maximum Extent Practicable” (MEP) for Bowling Green.Step 1: Define “Maximum Extent Practicable” (MEP) for Bowling Green. Step 2: Establish how much treatment is enough.Step 2: Establish how much treatment is enough. Step 3: Develop a “doable” program.Step 3: Develop a “doable” program.

8. Civil & Environmental Consultants, Inc. Identify pollutant of concern (303d lists, TMDLs) Identify pollutant of concern (303d lists, TMDLs) Establish pollutant load reduction goal Establish pollutant load reduction goal –Based upon accepted research, other communities –No need to reinvent the wheel… Develop design features and practices that work for the City Develop design features and practices that work for the City –Treatment volume based on impervious surfaces –Consider local limitations (karst, groundwater table) How the City Defines MEP:

9. Civil & Environmental Consultants, Inc. Sediment or total suspended solids (TSS)Sediment or total suspended solids (TSS) Available BMP researchAvailable BMP research Many other programs using TSS as pollutant of concernMany other programs using TSS as pollutant of concern KYR10000 – references 80% TSS reductionKYR10000 – references 80% TSS reduction Sediment is no. 1 pollutant in nationSediment is no. 1 pollutant in nation Pollutant of Concern

10. Civil & Environmental Consultants, Inc. Impervious Cover TSS loading is higher from impervious coverTSS loading is higher from impervious cover Impervious cover…Impervious cover…

11. Civil & Environmental Consultants, Inc. Roads Parking Buildings Sidewalks Driveways

12. Civil & Environmental Consultants, Inc. Establish treatment goals/limits Water Quality Treatment required for sites that disturb 1 ac or more AND add 10,000ft 2 or more new impervious surfacesWater Quality Treatment required for sites that disturb 1 ac or more AND add 10,000ft 2 or more new impervious surfaces WQv = [(P Rv)(A)]/12WQv = [(P Rv)(A)]/12 Where,Where, WQv is the water quality treatment volume (ac-ft)WQv is the water quality treatment volume (ac-ft) P is the average rainfall in inches, (in the case of Bowling Green, is 1.1 inches);P is the average rainfall in inches, (in the case of Bowling Green, is 1.1 inches); Rv is the volumetric runoff coefficient, which is:Rv is the volumetric runoff coefficient, which is: Rv = 0.05 + 0.009(I), where I is the percent impervious cover;Rv = 0.05 + 0.009(I), where I is the percent impervious cover; and A is the area in acresand A is the area in acres Set treatment goal based upon pollutant of concern…Set treatment goal based upon pollutant of concern…

13. Civil & Environmental Consultants, Inc. A “Doable” Program Presumptive program:Presumptive program: –IF you design as described in BMP Manual –IF you install per the approved plans – AND –IF you maintain the BMP per the Operation & Maintenance Plan – THEN –You are in compliance. Discharge influent/effluent testing not required (for now…)Discharge influent/effluent testing not required (for now…)

14. Civil & Environmental Consultants, Inc. B est M anagement P ractices Mitigate storm water quality and quantity damages from developmentMitigate storm water quality and quantity damages from development WetlandsWet PondsDry Ponds Bioretention areas Water quality swales Infiltration trench Sand filterWater quality units Manufactured devices

15. Civil & Environmental Consultants, Inc. Ponds Dry pondsDry ponds –Outlet structure –Dry storage area –60% TSS reduction

16. Civil & Environmental Consultants, Inc. Ponds Wet pondsWet ponds –Outlet structure –Permanent pool –80% TSS reduction

17. Civil & Environmental Consultants, Inc. Ponds VariationsVariations –Micropool –Extended detention –Multiple ponds –Pocket ponds

18. Civil & Environmental Consultants, Inc. Wetlands Outlet structureOutlet structure Shallow wet treatment areaShallow wet treatment area Upland dry storageUpland dry storage Plants are keyPlants are key Length of flow (residence time) keyLength of flow (residence time) key 75% TSS reduction75% TSS reduction

19. Civil & Environmental Consultants, Inc.

21. Bioretention areas Outlet structureOutlet structure –Small storm & large storms Dry treatment areaDry treatment area –Depressed planting area –Specific soils –Under drain 80% TSS reduction80% TSS reduction

22. Civil & Environmental Consultants, Inc.

24. Open Channel Systems Simple outlet systemSimple outlet system Treatment areaTreatment area DryDry –good in most all land use applications –Underdrain system WetWet –Not well accepted in residential –Long wetland

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26. Sand filters Many variationsMany variations Best suited for non-residentialBest suited for non-residential Typically undergroundTypically underground Must receive drainage from only impervious surfacesMust receive drainage from only impervious surfaces

27. Civil & Environmental Consultants, Inc. Infiltration trenches Limited application due to karst topographyLimited application due to karst topography

28. Civil & Environmental Consultants, Inc. Manufactured BMPs Treatment mechanisms different from non-manufactured BMPsTreatment mechanisms different from non-manufactured BMPs Must provide 3 rd party testing to verify pollutant removal to get approved for useMust provide 3 rd party testing to verify pollutant removal to get approved for use Nashville has similar program – will use Nashville’s list of approved BMPs and reduction capabilitiesNashville has similar program – will use Nashville’s list of approved BMPs and reduction capabilities

29. Civil & Environmental Consultants, Inc. Summary table

30. Civil & Environmental Consultants, Inc. WQMPs Trigger: 1 ac or more disturbance and 10,000 ft2 new impervious surfacesTrigger: 1 ac or more disturbance and 10,000 ft2 new impervious surfaces –Or part of a larger common plan of development DPW is point of contact for info on WQMPDPW is point of contact for info on WQMP –P&Z will have checklists and general info

31. Civil & Environmental Consultants, Inc. Conservation Subdivision WQMP =WQMP = –Clearly defined clearing limits –Total impervious surfaces for development cannot exceed 15% –Minimum lot sizes – 1 acre –Disconnected roof drains –Stabilized sinkhole basins No additional WQ treatment requiredNo additional WQ treatment required

32. Civil & Environmental Consultants, Inc. Hot Spot Landuses Pretreatment required for following landuses:Pretreatment required for following landuses: 1.Automotive Fueling Facilities 2.Automotive Repair Facilities 3.Restaurants with grease collection and disposal 4.Other landuses as determined to have a high potential of pollutant discharge into the MS4 as determined by the City Engineer Typically, oil grease separators, hydrodynamic separators, etc.Typically, oil grease separators, hydrodynamic separators, etc.

33. Civil & Environmental Consultants, Inc. Asbuilt Certification Need to verifyNeed to verify –That BMP was installed per approved plans –That WQv treatment goals being met Engineer and surveyorEngineer and surveyor Asbuilt must be approved before:Asbuilt must be approved before: –Bonds released (S/D) –CO issued (non-S/D)

34. Civil & Environmental Consultants, Inc. Maintenance City to maintain BMPs inCity to maintain BMPs in –residential areas –on public ROWs Landowner to maintain all other BMPsLandowner to maintain all other BMPs All BMPsAll BMPs –O&M Plan –Routine inspections –Annual inspection certification

35. Civil & Environmental Consultants, Inc. O&M Plan Includes the following:Includes the following: –BMP Maintenance Agreement Privately owned BMPs onlyPrivately owned BMPs only –BMP location map –BMP schematics –BMP maintenance and inspection templates –Annual BMP report template Recorded with the deedRecorded with the deed Privately owned BMPs onlyPrivately owned BMPs only O&M Plan Lashlee Landings - Agreement - Location map - Schematics - Inspection checklists

36. Civil & Environmental Consultants, Inc. Detention Pond Bioretention #1 Bioretention #2 Drainage Easement Access Easement Drainage Easement BMP Location Map

37. Civil & Environmental Consultants, Inc. BMP Schematics 18” storage 2.5’ planting media 6” #57 stone 4” perforated plastic pipe Geotextile fabric Redbud, 10’ O.C Daylilies, 2’ O.C.

38. Civil & Environmental Consultants, Inc. BMP Schematics

39. Civil & Environmental Consultants, Inc. BMP Inspection Checklists

40. Civil & Environmental Consultants, Inc. Residential Example: Lashlee Landing

41. Civil & Environmental Consultants, Inc. Site Data - 51 Single Family Lots Area = 38 ac. Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops WQv=[(P Rv)(A)]/12 Rv = Rv = 0.05 + 0.009(I) WQv = [1.1*(0.05+0.009*36)*38]/12 = 1.30 ac-ft Scenario 1: Wet pond = 80% TSS DA1, DA2, DA3 routed to pond Single Drainage Area

42. Civil & Environmental Consultants, Inc. Site Data - 51 Single Family Lots Area = 38 ac. Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops 2 drainage basins Each has to treat WQv; weighted TSS reduction goal Drainage Area (DA) 1 Area = 7.6 ac. Imp Area = 2.25 ac; I = 2.25/7.6 = 30.0% Drainage Area (DA) 2 Area = 30.4 ac. Imp Area = 11.55 ac; I = 11.55/30.4 = 38.0% WQv=[(P Rv)(A)]/12 Rv = Rv = 0.05 + 0.009(I) DA1 Rv = 0.05 + 0.009(30) = 0.32 WQv = [(1.1*0.32)*7.6]/12 = 0.22 ac-ft DA2 Multiple Drainage Areas Rv = 0.05+0.009(38) = 0.39 WQv = [(1.1*0.39)*30.4]/12 =1.09 ac-ft

43. Civil & Environmental Consultants, Inc. DA1 Rv = 0.05 + 0.009(30) = 0.32 WQv = [(1.1*0.32)*7.6]/12 = 0.22 ac-ft - 2 Dry WQ Swales - provides 0.11 ac-ft of WQv in each - Dry WQ Swales = 90% TSS reduction DA2 Rv = 0.05+0.009(38) = 0.39 WQv = [(1.1*0.39)*30.4]/12 =1.09 ac-ft - Wet pond - provides 1.09 ac-ft of WQv - TSS reduction = 80% %TSS = (7.6*90)+(30.4*80)/38ac = 82% TSS Therefore, site okay Multiple Drainage Areas

44. Civil & Environmental Consultants, Inc. Treatment Train When one BMP discharges into anotherWhen one BMP discharges into another Discharge from upstream BMP will be “clean” so downstream BMP TSS reduction will be less effectiveDischarge from upstream BMP will be “clean” so downstream BMP TSS reduction will be less effective Bioretention 80% TSS Dry Detention 60% TSS Flow TSS reduction = 80+60 – (80x60)/100 = 92%

45. Civil & Environmental Consultants, Inc. Scenario 2: DA1 = Dry detention = 60% TSS DA1 = 10ac @60% TSS DA2 = 15ac @80% TSS then 60% (treatment train) DA3 = 13 ac @90% TSS DA1DA2 Bioretention areas to dry detention Dry Swales TSS total = ([10ac x 60] + [15ac x 92] + [13ac x 90]) / 38 = 82.8% TSS DA2 %TSS reduction = 80+60 – (80x60)/100 = 92%

46. Civil & Environmental Consultants, Inc. Commercial Example: Creekwood Village

47. Civil & Environmental Consultants, Inc. Creekwood Village S/D Multi-familyMulti-family Dry regional detention facilityDry regional detention facility Goal - Regional WQMP:Goal - Regional WQMP: –Provide regional WQ BMPs –Establish builtout imperviousness per lot Problem:Problem: –Assume 15 acres, 40 lots w/80% imperviousness per lot, 1500 linear ft of roadway. –What is WQv? –What BMPs might work? –Where?

48. Civil & Environmental Consultants, Inc. Lots 6 and 7 Regional WQMPRegional WQMP –Review against restrictions –If above restrictions, require additional on lot treatment Individual WQMPIndividual WQMP –Develop WQMPs as unit (lots 6-7) or separately

49. Civil & Environmental Consultants, Inc. Dry Pond Bioretention #1 Bioretention #2 Drainage Easement Access Easement Problem: Lot 7 – 0.67 ac total, 25% impervious cover Lot 6 – 1.1 ac total, 23% impervious cover Problem: What is the WQv? Does this WQMP meet the TSS reduction goal if developed as one WQMP?

50. Civil & Environmental Consultants, Inc. Questions and Discussion