Upload
temple
View
29
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Water Quality Management Program Staff Training. Agenda. Why is this change necessary? Program rationale Describe new BMPs Plans review process Operation and Maintenance Plan Design examples. NPDES Phase 2 regulations:. 6 Minimum Control Measures - PowerPoint PPT Presentation
Citation preview
Civil & Environmental Consultants, Inc.
Water Quality Management Program
Staff Training
Civil & Environmental Consultants, Inc.
• Why is this change necessary?Why is this change necessary?
• ProgrProgram rationaleam rationale
• Describe new BMPsDescribe new BMPs
• Plans review processPlans review process
• Operation and Maintenance PlanOperation and Maintenance Plan
• Design examplesDesign examples
AgendaAgenda
Civil & Environmental Consultants, Inc.
• 6 Minimum Control Measures6 Minimum Control Measures
• Post construction storm water quality Post construction storm water quality treatmenttreatment
• “…“…treat storm water to the maximum treat storm water to the maximum extent practicable…”extent practicable…”
• All new developments and All new developments and redevelopments disturbing 1+ acresredevelopments disturbing 1+ acres
NPDES Phase 2 regulations:NPDES Phase 2 regulations:
Civil & Environmental Consultants, Inc.
Steps Taken to Date: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 Developed plan review and permitting processesprocesses
• TrainingTraining
Civil & Environmental Consultants, Inc.
ScheduleSchedule
• Effective date = March 31Effective date = March 31
• If plan has been platted and has approved If plan has been platted and has approved SWMP, no additional storm water quality SWMP, no additional storm water quality treatment required.treatment required.
Civil & Environmental Consultants, Inc.
About the program…About the program…
Civil & Environmental Consultants, Inc.
Program rationaleProgram rationale
• Step 1: Define “Maximum Extent Step 1: Define “Maximum Extent Practicable” (MEP) for Bowling Green.Practicable” (MEP) for Bowling Green.
• Step 2: Establish how much treatment is Step 2: Establish how much treatment is enough.enough.
• Step 3: Develop a “doable” program.Step 3: Develop a “doable” program.
Civil & Environmental Consultants, Inc.
Identify pollutant of concern (303d lists, TMDLs)Identify pollutant of concern (303d lists, TMDLs) Establish pollutant load reduction goalEstablish pollutant load reduction goal
– Based upon accepted research, other communitiesBased upon accepted research, other communities– No need to reinvent the wheel…No need to reinvent the wheel…
Develop design features and practices that work Develop design features and practices that work for the Cityfor the City– Treatment volume based on impervious surfacesTreatment volume based on impervious surfaces– Consider local limitations (karst, groundwater table)Consider local limitations (karst, groundwater table)
How the City DefinesHow the City Defines MEP: MEP:
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 Many other programs using TSS as pollutant of concernpollutant of concern
• KYR10000 – references 80% TSS KYR10000 – references 80% TSS reductionreduction
• Sediment is no. 1 pollutant in nationSediment is no. 1 pollutant in nation
Pollutant of ConcernPollutant of Concern
Civil & Environmental Consultants, Inc.
Impervious CoverImpervious Cover
• TSS loading is higher from impervious TSS loading is higher from impervious covercover
• Impervious cover…Impervious cover…
Civil & Environmental Consultants, Inc.
Roads
Parking
Buildings
Sidewalks
Driveways
Civil & Environmental Consultants, Inc.
Establish treatment goals/limitsEstablish treatment goals/limits• Water Quality Treatment required for sites that disturb 1 ac or Water Quality Treatment required for sites that disturb 1 ac or
more AND add 10,000ftmore AND add 10,000ft2 2 or more new impervious surfacesor more new impervious surfaces
• WQv WQv = [(= [(P RvP Rv)()(AA)]/12)]/12
• Where,Where,• WQv WQv is the water quality treatment volume (ac-ft)is the water quality treatment volume (ac-ft)• P P is the average rainfall in inches, (in the case of Bowling Green, is is the average rainfall in inches, (in the case of Bowling Green, is
1.1 inches);1.1 inches);• Rv Rv is the volumetric runoff coefficient, which is:is the volumetric runoff coefficient, which is:• Rv Rv = 0.05 + 0.009(= 0.05 + 0.009(II), where I is the percent impervious cover;), where I is the percent impervious cover;• and and A A is the area in acresis the area in acres
• Set treatment goal based upon pollutant of concern…Set treatment goal based upon pollutant of concern…
Civil & Environmental Consultants, Inc.
A “Doable” ProgramA “Doable” Program
• Presumptive program:Presumptive program:– IF you IF you designdesign as described in BMP Manual as described in BMP Manual– IF you IF you installinstall per the approved plans per the approved plans– ANDAND– IF you IF you maintainmaintain the BMP per the Operation & the BMP per the Operation &
Maintenance PlanMaintenance Plan– THENTHEN– You are in compliance.You are in compliance.
• Discharge influent/effluent testing not required Discharge influent/effluent testing not required (for now…)(for now…)
Civil & Environmental Consultants, Inc.
BBestest MManagement anagement PPracticesractices
• Mitigate storm water Mitigate storm water quality and quantity quality and quantity damages from damages from developmentdevelopment
Wetlands Wet Ponds Dry Ponds
Bioretention areas
Water quality swales
Infiltration trench
Sand filter Water quality units
Manufactured devices
Civil & Environmental Consultants, Inc.
PondsPonds
• Dry pondsDry ponds– Outlet Outlet
structurestructure– Dry storage Dry storage
areaarea– 60% TSS 60% TSS
reductionreduction
Civil & Environmental Consultants, Inc.
PondsPonds
• Wet pondsWet ponds– Outlet Outlet
structurestructure– Permanent Permanent
poolpool– 80% TSS 80% TSS
reduction reduction
Civil & Environmental Consultants, Inc.
PondsPonds
• VariationsVariations– MicropoolMicropool– Extended Extended
detentiondetention– Multiple pondsMultiple ponds– Pocket pondsPocket ponds
Civil & Environmental Consultants, Inc.
WetlandsWetlands
• Outlet structureOutlet structure• Shallow wet Shallow wet
treatment areatreatment area• Upland dry storageUpland dry storage• Plants are keyPlants are key• Length of flow Length of flow
(residence time) key(residence time) key• 75% TSS reduction75% TSS reduction
Civil & Environmental Consultants, Inc.
Civil & Environmental Consultants, Inc.
Civil & Environmental Consultants, Inc.
Bioretention areasBioretention areas
• Outlet structureOutlet structure– Small storm & large Small storm & large
stormsstorms
• Dry treatment areaDry treatment area– Depressed planting Depressed planting
areaarea– Specific soilsSpecific soils– Under drainUnder drain
• 80% TSS reduction80% TSS reduction
Civil & Environmental Consultants, Inc.
Civil & Environmental Consultants, Inc.
Civil & Environmental Consultants, Inc.
Open Channel SystemsOpen Channel Systems
• Simple outlet Simple outlet systemsystem
• Treatment areaTreatment area• Dry Dry
– good in most all land good in most all land use applicationsuse applications
– Underdrain systemUnderdrain system• Wet Wet
– Not well accepted in Not well accepted in residentialresidential
– Long wetlandLong wetland
Civil & Environmental Consultants, Inc.
Civil & Environmental Consultants, Inc.
Sand filtersSand filters
• Many variationsMany variations• Best suited for Best suited for
non-residentialnon-residential• Typically Typically
undergroundunderground• Must receive Must receive
drainage from only drainage from only impervious impervious surfacessurfaces
Civil & Environmental Consultants, Inc.
Infiltration trenchesInfiltration trenches
• Limited application Limited application due to karst due to karst topographytopography
Civil & Environmental Consultants, Inc.
Manufactured BMPsManufactured BMPs
• Treatment mechanisms different Treatment mechanisms different from non-manufactured BMPsfrom non-manufactured BMPs
• Must provide 3Must provide 3rdrd party testing to party testing to verify pollutant removal to get verify pollutant removal to get approved for useapproved for use
• Nashville has similar program – will Nashville has similar program – will use Nashville’s list of approved use Nashville’s list of approved BMPs and reduction capabilitiesBMPs and reduction capabilities
Civil & Environmental Consultants, Inc.
Summary tableSummary table
Civil & Environmental Consultants, Inc.
WQMPsWQMPs
• Trigger: 1 ac or more disturbance and Trigger: 1 ac or more disturbance and 10,000 ft2 new impervious surfaces10,000 ft2 new impervious surfaces– Or part of a larger common plan of Or part of a larger common plan of
developmentdevelopment
• DPW is point of contact for info on WQMPDPW is point of contact for info on WQMP– P&Z will have checklists and general infoP&Z will have checklists and general info
Civil & Environmental Consultants, Inc.
Conservation SubdivisionConservation Subdivision
• WQMP = WQMP = – Clearly defined clearing limitsClearly defined clearing limits– Total impervious surfaces for development Total impervious surfaces for development
cannot exceed 15%cannot exceed 15%– Minimum lot sizes – 1 acreMinimum lot sizes – 1 acre– Disconnected roof drainsDisconnected roof drains– Stabilized sinkhole basinsStabilized sinkhole basins
• No additional WQ treatment requiredNo additional WQ treatment required
Civil & Environmental Consultants, Inc.
Hot Spot LandusesHot Spot Landuses
• Pretreatment required for following landuses:Pretreatment required for following landuses:1.1. Automotive Fueling FacilitiesAutomotive Fueling Facilities
2.2. Automotive Repair FacilitiesAutomotive Repair Facilities
3.3. Restaurants with grease collection and disposalRestaurants with grease collection and disposal
4.4. Other landuses as determined to have a high Other landuses as determined to have a high potential of pollutant discharge into the MS4 as potential of pollutant discharge into the MS4 as determined by the City Engineerdetermined by the City Engineer
• Typically, oil grease separators, hydrodynamic Typically, oil grease separators, hydrodynamic separators, etc.separators, etc.
Civil & Environmental Consultants, Inc.
Asbuilt CertificationAsbuilt Certification
• Need to verify Need to verify – That BMP was installed per That BMP was installed per
approved plansapproved plans– That WQv treatment goals That WQv treatment goals
being metbeing met
• Engineer and surveyorEngineer and surveyor• Asbuilt must be approved Asbuilt must be approved
before:before:– Bonds released (S/D)Bonds released (S/D)– CO issued (non-S/D)CO issued (non-S/D)
Civil & Environmental Consultants, Inc.
MaintenanceMaintenance
• City to maintain BMPs in City to maintain BMPs in – residential areasresidential areas– on public ROWs on public ROWs
• Landowner to maintain all other BMPsLandowner to maintain all other BMPs
• All BMPsAll BMPs– O&M PlanO&M Plan– Routine inspectionsRoutine inspections– Annual inspection certificationAnnual inspection certification
Civil & Environmental Consultants, Inc.
O&M PlanO&M Plan
• Includes the following:Includes the following:– BMP Maintenance AgreementBMP Maintenance Agreement
• Privately owned BMPs onlyPrivately owned BMPs only
– BMP location mapBMP location map– BMP schematics BMP schematics – BMP maintenance and inspection templatesBMP maintenance and inspection templates– Annual BMP report templateAnnual BMP report template
• Recorded with the deedRecorded with the deed• Privately owned BMPs onlyPrivately owned BMPs only
O&M PlanO&M PlanLashlee LandingsLashlee Landings
- Agreement- Agreement- Location map- Location map- Schematics- Schematics
- Inspection checklists- Inspection checklists
Civil & Environmental Consultants, Inc.
Detention Pond
Bioretention #1
Bioretention #2
Drainage Easement
Access Easement
Drainage Easement
BMP Location MapBMP Location Map
Civil & Environmental Consultants, Inc.
BMP SchematicsBMP Schematics
18” storage
2.5’ planting media
6” #57 stone
4” perforated plastic pipe
Geotextile fabric
Redbud, 10’ O.CDaylilies, 2’ O.C.
Civil & Environmental Consultants, Inc.
BMP SchematicsBMP Schematics
Civil & Environmental Consultants, Inc.
Storm Water Bioretention Area Inspection Checklist for BMP Owners Site name: ___________________________________________________________________________________ BMP Number: _________________________________________________________________________________ Owner Change since last inspection? Y N Owner Name__________________________________________________________________________________ Address______________________________________________________________________________________ Phone Number ___________________________ Location: ____________________________________________ Inspection Date: ______________________________________ Time:__________________________________ Inspector: ___________________________________________________________________________________ Weather Conditions:____________________________________________________________________________ Was flow observed: If so, what was the appearance of the water (i.e. color, sheen, estimated flow rate, etc.)? ____________________________________________________________________________________________
Maintenance Item
Insp
ecte
d?
(Yes
/No)
Mai
nten
ance
ne
eded
? (Y
es/N
o)
Comments
Treatment area (Inspect after major storm events)
1. Evidence of drainage (Is water ponding less than 24 hrs after rain event?)
2. Signs of erosion noted (in contributing watershed or in bioretention area?)
3. Mulch condition – thin or decomposing? 4. Sediment deposits noted in treatment area?
5. Vegetation condition 6. Overflow spillway in good condition? 7. Other (describe)
Note: If any inspection items were checked “yes” for maintenance needed, list maintenance actions and dates completed below.
Maintenance Action Needed
Date
D
ue
Com
-ple
ted?
Y/N
Inspector signature: ____________________________________________________________________________
City of Bowling Green Storm Water Contact Information: 270-393-3628
BMP Inspection ChecklistsBMP Inspection Checklists
Civil & Environmental Consultants, Inc.
Residential Example: Residential Example: Lashlee LandingLashlee Landing
Civil & Environmental Consultants, Inc.
Site Data - 51 SingleFamily LotsArea = 38 ac.
Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops
WQv=[(P Rv)(A)]/12Rv = 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% TSSDA1, DA2, DA3 routed to pond
1
21
1
2211
)...(
)...(%
n n
n nn
AAA
ATSSATSSATSSTSS
Single Drainage AreaSingle Drainage Area
Civil & Environmental Consultants, Inc.
Site Data - 51 SingleFamily LotsArea = 38 ac.
Impervious Area = 13.8 ac 36% 3 ac in roadway and driveways, 10.8 ac in roof tops2 drainage basinsEach has to treat WQv; weighted TSS reduction goalDrainage Area (DA) 1Area = 7.6 ac.Imp Area = 2.25 ac; I = 2.25/7.6 = 30.0%Drainage Area (DA) 2Area = 30.4 ac.Imp Area = 11.55 ac; I = 11.55/30.4 = 38.0%
WQv=[(P Rv)(A)]/12Rv = Rv = 0.05 + 0.009(I)
DA1 Rv = 0.05 + 0.009(30) = 0.32WQv = [(1.1*0.32)*7.6]/12 = 0.22 ac-ftDA2 Multiple Drainage AreasMultiple Drainage AreasRv = 0.05+0.009(38) = 0.39WQv = [(1.1*0.39)*30.4]/12 =1.09 ac-ft
Civil & Environmental Consultants, Inc.
DA1 Rv = 0.05 + 0.009(30) = 0.32WQv = [(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
DA2Rv = 0.05+0.009(38) = 0.39WQv = [(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 okayMultiple Drainage AreasMultiple Drainage Areas
Civil & Environmental Consultants, Inc.
Treatment TrainTreatment Train
• When one BMP discharges into anotherWhen one BMP discharges into another• Discharge from upstream BMP will be “clean” so Discharge from upstream BMP will be “clean” so
downstream BMP TSS reduction will be less effectivedownstream BMP TSS reduction will be less effective
Bioretention80% TSS
Dry Detention60% TSSFlow Flow
TSS reduction = 80+60 – (80x60)/100 = 92%
100
)( BABATSStrain
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
DA1DA1
DA2DA2
Bioretention areas to dry
detention
Dry Swales
TSStotal = ([10ac x 60] + [15ac x 92] + [13ac x 90]) / 38 = 82.8% TSS
DA2 %TSS reduction
= 80+60 – (80x60)/100 = 92%
Civil & Environmental Consultants, Inc.
Commercial Example:Commercial Example:Creekwood VillageCreekwood Village
Civil & Environmental Consultants, Inc.
Creekwood Village S/DCreekwood Village S/D• Multi-familyMulti-family• Dry regional detention Dry regional detention
facilityfacility• Goal - Regional WQMP:Goal - Regional WQMP:
– Provide regional WQ Provide regional WQ BMPsBMPs
– Establish builtout Establish builtout imperviousness per lotimperviousness per lot
• Problem:Problem:– Assume 15 acres, 40 Assume 15 acres, 40
lots w/80% lots w/80% imperviousness per lot, imperviousness per lot, 1500 linear ft of 1500 linear ft of roadway.roadway.
– What is WQv?What is WQv?– What BMPs might What BMPs might
work?work?– Where?Where?
Civil & Environmental Consultants, Inc.
Lots 6 and 7Lots 6 and 7
• Regional WQMPRegional WQMP– Review against Review against
restrictionsrestrictions– If above restrictions, If above restrictions,
require additional on require additional on lot treatmentlot treatment
• Individual WQMPIndividual WQMP– Develop WQMPs as Develop WQMPs as
unit (lots 6-7) or unit (lots 6-7) or separatelyseparately
Civil & Environmental Consultants, Inc.
Dry Pond
Bioretention #1
Bioretention #2
Drainage Easement
Drainage EasementAccess
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?
Civil & Environmental Consultants, Inc.
Questions and DiscussionQuestions and Discussion