BMP Training Module 4BMP Training Module 4

Extended Dry Detention Basin Extended Dry Detention Basin and Infiltration Practicesand Infiltration Practices

Sponsored by: MARCSponsored by: MARCPresenters: Presenters:

Andy Sauer, P.E. (CDM)Andy Sauer, P.E. (CDM)Brenda Macke, P.E. (CDM)Brenda Macke, P.E. (CDM)

February 20, 2009

AgendaAgenda Lecture 1: Review of Module 1Lecture 1: Review of Module 1

Review Module 1 and WQv definitionReview Module 1 and WQv definition Overview of Extended Dry Detention Basin (EDDB)Overview of Extended Dry Detention Basin (EDDB)

10-Minute Break10-Minute Break Lecture 2: Extended Dry Detention Basin (EDDB)Lecture 2: Extended Dry Detention Basin (EDDB)

Design ExampleDesign Example Design ActivityDesign Activity

10-Minute Break10-Minute Break Lecture 3: Infiltration BMPsLecture 3: Infiltration BMPs

Infiltration BasinsInfiltration Basins Infiltration TrenchesInfiltration Trenches Porous PavementPorous Pavement

Lecture 1Lecture 1 OverviewOverview

Review watershed planning and BMP value rating process Review watershed planning and BMP value rating process (Module 1)(Module 1)

Overview of extended dry detention basins (EDDB) Overview of extended dry detention basins (EDDB)

Best Management Practice Best Management Practice (BMP)(BMP)

BestBest – State of the Practice – State of the Practice No definitive answerNo definitive answer Past experience, testing, research, Past experience, testing, research, Unique to siteUnique to site

ManagementManagement – Responsible Parties – Responsible Parties Improve water quality, meet NPDES Phase IIImprove water quality, meet NPDES Phase II Jurisdictional specificJurisdictional specific Meet specific requirements of a regionalMeet specific requirements of a regional

PracticePractice – Action or Implementation – Action or Implementation Practice = defined to carry out, apply, or to Practice = defined to carry out, apply, or to

do or perform often. do or perform often.

Basic BMP PrinciplesBasic BMP Principles

PlanPlan for stormwater management for stormwater management Sustainable and “be green”Sustainable and “be green” Provide a level of serviceProvide a level of service Improve water qualityImprove water quality

MimicMimic natural hydrology natural hydrology Increase initial abstraction Increase initial abstraction Promote infiltration, retention & ETPromote infiltration, retention & ET

““Treat”Treat” the stormwater runoff the stormwater runoff Natural processesNatural processes Treatment trainsTreatment trains

BMP Evaluation ProcessBMP Evaluation Process

Extended detention (40 hours) to increase treatment and decrease peak flows

PLAN

MIMIC

TREAT

Detention and TreatmentDetention and Treatment

Structural BMPs Structural BMPs detain runoffdetain runoff

Extended Detention Extended Detention BasinsBasins

• WetWet• DryDry

Extended Detention Extended Detention WetlandsWetlands

Infiltration basinsInfiltration basins

Typically used as Typically used as larger, centralized larger, centralized facilitiesfacilities

TREAT

Example siteExample site

Main Channel

Bridge

Streambank Biostabilization

CulvertRoadway

Grass Swale

Dry Detention

Commercial Building

Bio-Filters

Design Documents

– APWA 5600– BMP Manual– Watershed Master Plans

TREAT

Structural BMP ConsiderationStructural BMP Consideration

Pollutant removal efficiencyPollutant removal efficiency Water quality volumeWater quality volume Site suitabilitySite suitability Tributary area Tributary area Dimensions (depth, length-width ratio)Dimensions (depth, length-width ratio) OutletOutlet Emergency spillwayEmergency spillway Maintenance easementMaintenance easement Routine and non-routine maintenanceRoutine and non-routine maintenance

BMP EvaluationBMP EvaluationGeneral RuleGeneral Rule

Wat

er Q

ualit

y Water Q

uantity

Aesthetics/Amenity

BMP ManualBMP ManualDRAFT – In Progress

BMP ManualBMP ManualLevel of ServiceLevel of Service

Reduce VolumeReduce Volume• Infiltration Infiltration • Evapotranspiration (ET)Evapotranspiration (ET)

Remove total suspended solids (TSS) Remove total suspended solids (TSS) • SettlingSettling

Temperature Reduction Temperature Reduction • Urban heat islandUrban heat island

Remove oils and FloatablesRemove oils and Floatables• Screening and netting Screening and netting

Value Rating System – Value Rating System – Based on BMP GoalsBased on BMP Goals

Condensed Table 5Condensed Table 5

BMP value table is based on the 4 goals of BMP value table is based on the 4 goals of BMPsBMPs

BMP

Median Expected Effluent

EMC TSS

Water Quality Value

Volume Reduction

Temperature Reduction

Oils/Floatables Reduction

Overall Value

Vegetation N/A 5.25 2 1 1 9.25Rain Garden < 10 4 2 1 2 9.0Infiltration Practices < 10 4 2 1 2 9.0Bioretention < 10 4 1.5 1 2 8.5Pervious or Porous Pavement 10 - 20 3 1.5 1 2 7.5Extended Detention Wetland < 10 4 2 0 1 7.0Media Filtration Practices < 10 4 0 0 2 6.0Wetland Swale 10 - 20 3 1.5 0 2 6.5Bio-Swale 10 - 20 3 1.5 0 2 6.5Extended Wet Detention 10 - 20 3 2 -1 1 5.0Native Vegetation Swale 10 - 20 3 1 0 0 4.0Extended Dry Detention Basin 20 - 50 2 1 0 1 4.0Turf Grass Swale 10 - 20 3 0 0 0 3.0

Value Ratings

Post Development BMP Post Development BMP SelectionSelection

BMP

Median Expected Effluent

EMC TSS

Water Quality Value

Volume Reduction

Temperature Reduction

Oils/Floatables Reduction

Overall Value

Vegetation N/A 5.25 2 1 1 9.25Rain Garden < 10 4 2 1 2 9.0Infiltration Practices < 10 4 2 1 2 9.0Bioretention < 10 4 1.5 1 2 8.5

Pervious or Porous Pavement 10 - 20 3 1.5 1 2 7.5

Extended Detention Wetland < 10 4 2 0 1 7.0Media Filtration Practices < 10 4 0 0 2 6.0Wetland Swale 10 - 20 3 1.5 0 2 6.5Bio-Swale 10 - 20 3 1.5 0 2 6.5Extended Wet Detention 10 - 20 3 2 -1 1 5.0Native Vegetation Swale 10 - 20 3 1 0 0 4.0Extended Dry Detention Basin 20 - 50 2 1 0 1 4.0

Turf Grass Swale 10 - 20 3 0 0 0 3.0

Value Ratings

BMP Selection FlowchartBMP Selection Flowchart

Level Of Service

BMP Value Rating

Water Quality Volume/sizing

Placement, maintenance

Water Quality Volume (WQv)Water Quality Volume (WQv)

Water Quality Volume Water Quality Volume (WQv): The storage needed (WQv): The storage needed to capture and treat 90% of to capture and treat 90% of the average annual storm the average annual storm runoff volumerunoff volume

Water Quality Storm: The Water Quality Storm: The storm event that produces storm event that produces ≤ ≤ 90% volume of all daily 90% volume of all daily storms in a year storms in a year

Extended dry detention Extended dry detention basin design and infiltration basin design and infiltration system design is based on system design is based on the WQvthe WQv

WQv

2003 Kansas City Precip events

05

1015202530354045

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

Daily Precipitation (in)

# o

f d

ays

> o

r=

Kansas City Water Quality Kansas City Water Quality StormStorm

Water Quality Storm = 1.37 in

Young and McEnroe

(http://kcmetro.apwa.net)

Why Use the WQv to size Why Use the WQv to size BMP?BMP?

Retain runoff long enough to get Retain runoff long enough to get water quality benefitswater quality benefits InfiltrateInfiltrate Maintain vegetationMaintain vegetation

Reducing erosive flows from Reducing erosive flows from smaller runoff eventssmaller runoff events Less applicableLess applicable

Water Quality Volume Water Quality Volume CalculationCalculation

Two methodsTwo methods Short-Cut MethodShort-Cut Method

• Sites < 10 acresSites < 10 acres

• Only 1 predominant cover typeOnly 1 predominant cover type

Small Storm Hydrology MethodSmall Storm Hydrology Method• Larger or more heterogeneous drainage Larger or more heterogeneous drainage

areasareas

WQv Short-cut ExampleWQv Short-cut Example

GivenGiven Tributary area (ATributary area (ATributaryTributary) = 2.5 acres) = 2.5 acres %impervious = 80%%impervious = 80%

WQv = 1.37in * [0.05 + (0.009 * 80%)] = 1.06 in WQv = 1.37in * [0.05 + (0.009 * 80%)] = 1.06 in

Multiply by AMultiply by ATributaryTributary to get volume to get volume

1.06 * 1ft/12in * 2.5 acres = 1.06 * 1ft/12in * 2.5 acres = 0.22 ac-ft0.22 ac-ft

If only 50% impervious If only 50% impervious WQv = WQv = 0.14 ac-ft0.14 ac-ft

WQv CalculationWQv Calculation

Small Storm Hydrology MethodSmall Storm Hydrology Method

WQv = P*Weighted RvWQv = P*Weighted Rv

Weighted Rv = Weighted Rv = ΣΣ(Rv(Rvii*Ac*Acii)/Total area (ac))/Total area (ac)

RvRvii = Volumetric runoff coefficient for = Volumetric runoff coefficient for

impervious cover type (table)impervious cover type (table) AcAcii = Area of impervious cover type i (ac) = Area of impervious cover type i (ac)

Rv TableRv Table

BMP MANUAL SECTION 6, TABLE 5VOLUMETRIC COEFFICIENTS FOR URBAN RUNOFF FOR

DIRECTLY CONNECTED IMPERVIOUS AREAS(CLAYTOR AND SCHUELER 1996)

Rainfall Rainfall (inches)(inches)

Flat roofs and Flat roofs and large unpaved large unpaved

parking lotsparking lots

Pitched roofs and Pitched roofs and large impervious large impervious

areas areas (large parking lots)(large parking lots)

Small Small impervious impervious areas and areas and

narrow narrow streetsstreets

Silty Silty soils soils

HSG-BHSG-B

Clayey Clayey soils HSG-soils HSG-

C and DC and D

0.750.75 0.820.82 0.970.97 0.660.66 0.110.11 0.200.20

1.001.00 0.840.84 0.970.97 0.700.70 0.110.11 0.210.21

1.251.25 0.860.86 0.980.98 0.740.74 0.130.13 0.220.22

1.371.37 0.870.87 0.980.98 0.750.75 0.140.14 0.230.23

1.501.50 0.880.88 0.990.99 0.770.77 0.150.15 0.240.24

Note: a reduction factor may be applied to the Rv values for disconnected surfaces, consult the BMP manual hydrology section

WQv Small Storm ExampleWQv Small Storm Example

Given: AGiven: ATributaryTributary = 26 ac = 26 ac

Cover TypeCover Type RvRv Area (acres)Area (acres)

Flat roofsFlat roofs 0.870.87 1.61.6

Parking lotsParking lots 0.980.98 8.88.8

Narrow streetsNarrow streets 0.750.75 3.33.3

Silty soilSilty soil 0.140.14 12.312.3

( )∑ =××+×+×+×=××= inPAreaTotal

AcRvWQv ii 749.037.1

26

3.1214.03.375.08.898.06.187.0

Multiply by AMultiply by ATributaryTributary to get volume to get volume

Overview of Extended Dry Overview of Extended Dry Detention BasinDetention Basin

Extended Dry Detention Extended Dry Detention Basin (EDDB)Basin (EDDB)

Why the term “Extended” Why the term “Extended” Detention?Detention?

Extended: Designed to release the WQv over a period of 40 hours Extended: Designed to release the WQv over a period of 40 hours

Allows time for more particles and associated pollutants to Allows time for more particles and associated pollutants to settle outsettle out

Reduces the downstream velocity and erosive conditionsReduces the downstream velocity and erosive conditions More closely imitates natural release rates and durationMore closely imitates natural release rates and duration

Geomorphic Effects of Geomorphic Effects of Uncontrolled Urban RunoffUncontrolled Urban Runoff

0.1

1

10

100

1000

§� · q· B Ú y·

Exceedance Frequency for Exceedance Frequency for DetentionDetention

7-yr

2/yr

20/yr

Storm Return Interval more frequent than 1-yr

1-yr 10-yr 100-yr2-yr

Undeveloped

DevelopedUncontrolled

6/yr

F

low

40-Hour Drawdown Impacts40-Hour Drawdown Impacts

Storm Return Interval

more frequent than 1-yr

1-yr 10-yr 100-yr2-yr

F

low

Undeveloped

DevelopedUncontrolled

DevelopedControlled

0.80 psf

0.26 psf

0.1

1

10

100

1000

0.01 0.1 1 10 100

•10-year control•1-year control•WQv – extended detention with 40 hr drawdown

March 2008 ManualMarch 2008 ManualExtended DetentionExtended Detention

Water Quality (40-hr)Water Quality (40-hr) Pollutant removal throughPollutant removal through

• SettlingSettling• Biological uptake (more for Biological uptake (more for

wetland)wetland)• Detain and promote Detain and promote

infiltrationinfiltration

Stream Sustainability (40-hr)Stream Sustainability (40-hr) Mimic undeveloped Mimic undeveloped

conditions for full range of conditions for full range of hydrologyhydrology

Can meet flood control Can meet flood control objectivesobjectives

EDDB Major ComponentsEDDB Major Components

EDDB Inlet/ForebayEDDB Inlet/Forebay

Forebay

Traps sediment and trash and slows inflow velocitiesTraps sediment and trash and slows inflow velocities Forebay (optional) should be at least 10% of WQv and Forebay (optional) should be at least 10% of WQv and

separated from the main basin by an acceptable barrier. separated from the main basin by an acceptable barrier. Use energy dissipaters at inlets to reduce scour potentialUse energy dissipaters at inlets to reduce scour potential

EDDB Inlet/ForebayEDDB Inlet/Forebay

EDDB Pilot ChannelEDDB Pilot Channel

Pilot Channel

EDDB Pilot ChannelEDDB Pilot Channel

Conveys low flows Conveys low flows to the outlet to the outlet

Recommend lining Recommend lining with riprap with riprap

Olathe, KS

EDDB Main BasinEDDB Main Basin

Main Basin

EDDB Main BasinEDDB Main Basin

Designed to hold the WQv Designed to hold the WQv with a depth of 2 to 5 ftwith a depth of 2 to 5 ft

Does not maintain a Does not maintain a permanent poolpermanent pool

Shallow basins with larger Shallow basins with larger surface area have higher surface area have higher performanceperformance

Basin bottom should be at Basin bottom should be at least 2 ft above the wet least 2 ft above the wet season water tableseason water table

For KC Metro, can be used for For KC Metro, can be used for limited passive recreation limited passive recreation such as trailssuch as trails

EDDB Outlet StructureEDDB Outlet Structure

Outlet

EDDB Outlet StructureEDDB Outlet Structure

Release the WQv over a Release the WQv over a period of 40 hrperiod of 40 hr

Protected by well screens, Protected by well screens, trash racks or gratestrash racks or grates

Located as far from inlet as Located as far from inlet as possiblepossible

Various outlet structure Various outlet structure typestypes Single OrificeSingle Orifice

Perforated Riser or PlatePerforated Riser or Plate

V-notch Weir V-notch Weir Source: Hubbard Brook LTER

EDDB OutfallEDDB Outfall

Outfall

EDDB Outfall and Emergency EDDB Outfall and Emergency SpillwaySpillway

Used to convey Used to convey flood flows safely flood flows safely without overtopping without overtopping the basinthe basin

Required unless Required unless main outlet is main outlet is designed to pass designed to pass 1% design storm 1% design storm

Olathe, KS

EDDB Maintenance AccessEDDB Maintenance Access

Maintenance Access

EDDB Vegetation EDDB Vegetation

Function of facility Function of facility determines determines vegetation selection vegetation selection

Vegetation typesVegetation types Native grasses Native grasses

(preferred)(preferred) TurfTurf

EDDB Vegetation EDDB Vegetation

USDA-NRCS PLANTS

Database / Hitchcock, A.S.

Buffalo Grass

Robert H. Mohlenbrock @

USDA-NRCS PLANTS Database

Woodland Sedge

Jennifer Anderson @ USDA-

NRCS PLANTS Database

Big Bluestem

EDDB Site Selection EDDB Site Selection

Soil permeability will Soil permeability will impact performanceimpact performance

Clay soils with low Clay soils with low depths to bedrock pose depths to bedrock pose siting limitationssiting limitations

Basin bottom must be Basin bottom must be at least 1-2 ft above wet at least 1-2 ft above wet season groundwater season groundwater tabletable

Backfilling with high Backfilling with high permeable soil should permeable soil should be consideredbe considered

EDDB Site Selection EDDB Site Selection

Off-line, outside of Off-line, outside of stream corridorstream corridor

Can be located within Can be located within larger flood control larger flood control facilitiesfacilities

Not on fill sites or steep Not on fill sites or steep slopes (unless slopes (unless enhanced)enhanced)

Use fences and Use fences and landscaping to impede landscaping to impede access access

Olathe, KS

WQv

Flood Control Volume

Incorporating Flood Control Incorporating Flood Control BenefitsBenefits

WQv

slotted weir for control of WQvx-section 100-yr pool

outlet pipe sized tocontrol 100-yr outflow

EDDB AdvantagesEDDB Advantages

Relatively easy to construct Relatively easy to construct and inexpensiveand inexpensive

Settling of suspended Settling of suspended solids solids

Flood control via peak Flood control via peak discharge attenuationdischarge attenuation

Control of channel erosion Control of channel erosion by reducing downstream by reducing downstream flow velocitiesflow velocities

Recreational benefits Recreational benefits (mainly trails)(mainly trails)

California Stormwater Quality Association

EDDB DisadvantagesEDDB Disadvantages

Not as aesthetically Not as aesthetically pleasing as other pleasing as other BMPs BMPs

Not effective at Not effective at removal of soluble removal of soluble pollutantspollutants

Difficult to identify Difficult to identify sites with sufficient sites with sufficient infiltration capacityinfiltration capacity

Questions?

10 minute break

Lecture 2: EDDB Design Lecture 2: EDDB Design Example and ActivityExample and Activity

Water quality storage volumeWater quality storage volume Outlet structureOutlet structure

Orifice Orifice Perforated riser or plate Perforated riser or plate V-notch weirV-notch weir

Trash rackTrash rack Basin shapeBasin shape Forebay (Optional)Forebay (Optional) Side SlopesSide Slopes VegetationVegetation

Design ExampleDesign Example

Design an EDDB for a 26-acre commercial development. Design an EDDB for a 26-acre commercial development. Size the EDDB to capture the WQv.Size the EDDB to capture the WQv. Size an outlet structure to release the WQv over 40 Size an outlet structure to release the WQv over 40

hours.hours.

Step 1:Step 1: Calculate Water Calculate Water Quality Storage Volume WQvQuality Storage Volume WQv

Two methodsTwo methods Short-Cut MethodShort-Cut Method

• Sites < 10 acresSites < 10 acres• Only 1 predominant cover typeOnly 1 predominant cover type

Small Storm Hydrology MethodSmall Storm Hydrology Method• Larger or more heterogeneous drainage Larger or more heterogeneous drainage

areasareas

As tributary area is 26 acres, Small Storm As tributary area is 26 acres, Small Storm Hydrology Method will be used.Hydrology Method will be used.

Equation: WQvEquation: WQv

Small Storm Hydrology MethodSmall Storm Hydrology Method

WQv = (P)*(Weighted Rv)WQv = (P)*(Weighted Rv)

Weighted Rv = Weighted Rv = ΣΣ(Rv(Rvii*Ac*Acii)/Total area (ac))/Total area (ac)

• RvRvii = Volumetric runoff coefficient for cover type (Table = Volumetric runoff coefficient for cover type (Table

7)7)

• AcAc ii = Area of cover type i (ac) = Area of cover type i (ac)

Rv TableRv TableTABLE 7

VOLUMETRIC COEFFICIENTS FOR URBAN RUNOFF FORDIRECTLY CONNECTED IMPERVIOUS AREAS

(CLAYTOR AND SCHUELER 1996)

Rainfall Rainfall (inches)(inches)

Flat roofs and Flat roofs and large unpaved large unpaved

parking lotsparking lots

Pitched roofs and Pitched roofs and large impervious large impervious

areas areas (large parking lots)(large parking lots)

Small Small impervious impervious areas and areas and

narrow narrow streetsstreets

Silty Silty soils soils

HSG-BHSG-B

Clayey soils Clayey soils HSG-C and HSG-C and

DD

0.750.75 0.820.82 0.970.97 0.660.66 0.110.11 0.200.20

1.001.00 0.840.84 0.970.97 0.700.70 0.110.11 0.210.21

1.251.25 0.860.86 0.980.98 0.740.74 0.130.13 0.220.22

1.371.37 0.870.87 0.980.98 0.750.75 0.140.14 0.230.23

1.501.50 0.880.88 0.990.99 0.770.77 0.150.15 0.240.24

Note: a reduction factor may be applied to the Rv values for disconnected surfaces, consult the BMP hydrology section

Water Quality Control Water Quality Control Volume Volume

Cover TypeCover Type RvRv Area (acres)Area (acres)

Flat roofsFlat roofs 0.870.87 1.61.6

Parking lotsParking lots 0.980.98 8.88.8

Narrow streetsNarrow streets 0.750.75 3.33.3

Silty soilSilty soil 0.140.14 12.312.3

( )∑ ∑ =×

×+×+×+×=××= inP

AreaTotal

AcRvWQv ii 749.037.1

26

3.1214.3.375.8.898.6.187.

Water Quality Storage Water Quality Storage VolumeVolume

Convert WQv from inches to ac-ft by converting Convert WQv from inches to ac-ft by converting inches to feet and multiplying by the tributary areainches to feet and multiplying by the tributary area

Add 20 percent to account for silt and sediment Add 20 percent to account for silt and sediment depositiondeposition

= (0.749)*(1ft/12in)*26ac = 1.62*1.20

Step 2:Step 2: Determine Outlet Determine Outlet StructureStructure

Single Orifice

Perforated Riser or Plate

V-notch Weir

Outlet StructureOutlet Structure

Outlet sized to release Outlet sized to release WQWQvv (ac-ft) within 40 (ac-ft) within 40

hourshours Locate outlet as far away Locate outlet as far away

from inlet as possiblefrom inlet as possible Avoid short-circuitingAvoid short-circuiting

The facility must bypass The facility must bypass 1% storm event1% storm event

Provide at least 1ft of Provide at least 1ft of freeboard above WQfreeboard above WQVV

stage stage

Option 1:Option 1: Single Orifice Outlet Single Orifice Outlet

Single Orifice OutletSingle Orifice Outlet

i.i. Depth of water quality volume at outlet (ZDepth of water quality volume at outlet (ZWQWQ)) Dependent on site conditions – designer determinedDependent on site conditions – designer determined

ii.ii. Average head of WQv over invert of orifice, HAverage head of WQv over invert of orifice, HWQ WQ (ft)(ft)

HHWQWQ = 0.5*Z = 0.5*ZWQWQ

iii.iii. Average water quality outflow rate, QAverage water quality outflow rate, QWQWQ (cfs) (cfs)

QQWQWQ = (WQ = (WQVV * 43,560) / (40 * 3,600) * 43,560) / (40 * 3,600)

Single Orifice OutletSingle Orifice Outlet

= 0.5*3.0ft

= (1.62*43,560)/(40*3600)

Single Orifice Outlet CSingle Orifice Outlet Coo

iv. Set orifice coefficient (Co) depending on orifice plate thickness

� Do must be > or = 4 inches to prevent clogging

� Co = 0.66 if plate thickness is < Do

� Co = 0.80 if plate thickness is > Do

Single Orifice Outlet Single Orifice Outlet

v.v. Orifice diameter (DOrifice diameter (Doo) must be greater than 4 ) must be greater than 4 inches, otherwise use weir or riserinches, otherwise use weir or riser

( )WQoWQo H * g * 2 * * C / Q * 2 * 12 D π=

Single Orifice Outlet SizingSingle Orifice Outlet Sizing

Do=12*2*(0.49/(0.66*π*(2*32.2*1.5)0.5))0.5

Option 2: Option 2: Perforated Riser or Perforated Riser or Plate OutletPlate Outlet

Photo taken by Larry Roesner

Photo taken by Larry Roesner

Perforated Riser or Plate Perforated Riser or Plate OutletOutlet

Calculate outlet area per row of Calculate outlet area per row of perforations (Aperforations (Aoo))

AAoo (in (in22) = WQ) = WQvv / (0.013 * Z / (0.013 * ZWQWQ22 + 0.22 * Z + 0.22 * ZWQWQ – 0.1) – 0.1)

Assuming a single column calculate the Assuming a single column calculate the diameter of a single perforation for each diameter of a single perforation for each rowrow

DD11 = (4 * A = (4 * Aoo / / π)π)1/21/2

If DIf D11 is greater than 2 inches add more is greater than 2 inches add more

columnscolumns

nc = 4

Perforated Riser or Plate Perforated Riser or Plate OutletOutlet

= 1.62/(0.013*3.02+0.22*3.0–0.1)

= (4*2.4/π)1/2

Perforated Riser or Plate Perforated Riser or Plate OutletOutlet

Use number of columns to determine exact Use number of columns to determine exact perforation diameterperforation diameter

DDperfperf = (4 / = (4 / ππ * A * Aoo / n / ncc))1/21/2

Using a 4” center to center vertical spacing and Using a 4” center to center vertical spacing and ZZWQWQ, determine number of rows (n, determine number of rows (nvv))

nnvv = Z = ZWQWQ / 4 / 4

nv = 5

Perforated Riser or Plate Perforated Riser or Plate OutletOutlet

= 1.62/(0.013*3.02+0.22*3.0–0.1)

= (4*2.4/π)1/2

= (4/π*2.4/1)1/2

= (ZWQ*12in)/4

Option 3:Option 3: V-Notch Weir Outlet V-Notch Weir Outlet

Dr. Robert Pitt Source: Hubbard Brook LTER

V-Notch Weir Outlet DesignV-Notch Weir Outlet Design

i.i. Depth of water quality volume at outlet (ZDepth of water quality volume at outlet (ZWQWQ)) Dependent on site conditions – designer determinedDependent on site conditions – designer determined

ii.ii. Calculate HCalculate HWQWQ over weir notch over weir notch

HHWQWQ=0.5*Z=0.5*ZWQWQ

iii.iii. Calculate the average water quality pool outflow Calculate the average water quality pool outflow rate Qrate QWQWQ (cfs) (cfs)

QQWQWQ = (WQv * 43,560)/(40 * 3,600) = (WQv * 43,560)/(40 * 3,600)

V-Notch Weir Outlet ExampleV-Notch Weir Outlet Example

= 0.5*3.0ft

= (1.62*43,560)/(40*3600)

V-Notch Weir Outlet DesignV-Notch Weir Outlet Design

Calculate required v-notch weir angleCalculate required v-notch weir angle

θ = 2 * (180 / π) * arctan (Qθ = 2 * (180 / π) * arctan (QWQWQ/(C/(Cvv * H * HWQWQ5/25/2))))

CCVV = V-notch weir coefficient = 2.5 = V-notch weir coefficient = 2.5

If θ is <20º set θ to 20ºIf θ is <20º set θ to 20º

Calculate top width of v-notch weir Calculate top width of v-notch weir (W(WVV))

WWvv = 2 * Z = 2 * ZWQWQ * Tan ( * Tan (θ / 2)θ / 2)

Convert θ to radians to calculate WConvert θ to radians to calculate WVV

Source: Hubbard Brook LTER

θ

V-Notch Weir Outlet ExampleV-Notch Weir Outlet Example

= 2*(180/π)*actan(0.49/(2.5*1.55/2))

Since Since θθ < 20º set < 20º set θθ to 20º to 20º

= 2*3.0*tan(20º*π/(2*180))

20º

1.1

Step 3:Step 3: Basin Shape Basin Shape

California Stormwater Quality Association

3W

W

Step 4: Step 4: Forebay (Optional)Forebay (Optional)

Volume (VolVolume (VolFBFB) should be at least 10% of WQv) should be at least 10% of WQv

Sides and bottom paved or hardenedSides and bottom paved or hardened

Surface area (ASurface area (AFBFB):):

AAFBFB = Vol = VolFBFB / Z / ZFBFB

Forebay (Optional)Forebay (Optional)

= 0.10*6.23

= 0.62/3.0

EDDB Design ActivityEDDB Design Activity

ActivityActivity

Design an extended dry detention basin (EDDB) to capture the Design an extended dry detention basin (EDDB) to capture the WQv from a 52-acre development. Design a single orifice WQv from a 52-acre development. Design a single orifice outlet to release the WQv over 40-hours.outlet to release the WQv over 40-hours.

Cover Type Area (acres)

Commercial Center

Flat Roofs 5

Large Paved Parking Lots 6

Clayey Soils 1

Streets 2

Medium Density Residential

Pitched Roofs 15

Paved Driveways 7

Clayey Soils 11

Streets 5

Totals 52

Activity SolutionActivity Solution

Questions?

10 minute break

Lecture 3: Infiltration BMPsLecture 3: Infiltration BMPs

Infiltration basinInfiltration basin Infiltration trenchInfiltration trench Pervious pavement Pervious pavement

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I’Lan Park, Leawood, KS

Infiltration Practices Infiltration Practices

AdvantagesAdvantages

Provides 100% load reduction for captured runoff Provides 100% load reduction for captured runoff volumevolume

Flood control via peak discharge attenuationFlood control via peak discharge attenuation

Control of channel erosion by reducing Control of channel erosion by reducing downstream flow velocitiesdownstream flow velocities

DisadvantagesDisadvantages

Sediment can clog an infiltration facilitySediment can clog an infiltration facility

Tributary area should be stabilizedTributary area should be stabilized

Not suitable in areas with high water table (1-Not suitable in areas with high water table (1-2 feet from ground surface)2 feet from ground surface)

Soils must have a minimum saturated Soils must have a minimum saturated hydraulic conductivityhydraulic conductivity

Risk of contaminating groundwaterRisk of contaminating groundwater

Infiltration Practices Infiltration Practices

CautionCaution

Infiltration capacity of soils in the MARC region Infiltration capacity of soils in the MARC region is general low (<0.5 in/hr)is general low (<0.5 in/hr)

High water tables are also a common concern High water tables are also a common concern related to these practicesrelated to these practices

Be very careful in site selection for infiltration Be very careful in site selection for infiltration basins or trenchesbasins or trenches

Infiltration BasinInfiltration Basin

Vegetated basin floor

Emergency Spillway

Pretreatment

Outfall

OutletBackup Drain

Infiltration BasinInfiltration Basin

WQv

Infiltration Basin PretreatmentInfiltration Basin Pretreatment

Pretreatment

Used to remove as many Used to remove as many of the suspended solids of the suspended solids as possibleas possible

Various typesVarious types Grit Chambers Grit Chambers Swales with Check DamsSwales with Check Dams Filter Strips Filter Strips Sediment ForebaysSediment Forebays

Vegetated basin floor

Infiltration Basin FloorInfiltration Basin Floor

•Basin floor should be as level as possible for even distribution

Infiltration BasinInfiltration Basin

Emergency Spillway

Outfall

Outlet

Infiltration Basin Infiltration Basin Outlet/Overflow StructuresOutlet/Overflow Structures

Must pass flood flows Must pass flood flows without damaging the without damaging the structurestructure

OptionsOptions WeirWeir Overflow pipeOverflow pipe

Portland OR (www.lowimpactdevelopment.org)

Infiltration Basin Backup Infiltration Basin Backup DrainDrain

Backup Drain

Used to Used to drain the drain the basin if basin if ponding ponding persists for persists for more than more than 72 hours72 hours

Infiltration BasinInfiltration Basin

Infiltration Basin Key Design Infiltration Basin Key Design CriteriaCriteria

Maximum of 2 acre tributary Maximum of 2 acre tributary areaarea

Off line, outside of stream Off line, outside of stream corridors corridors

Where soil permeability Where soil permeability and water table is suitableand water table is suitable

Minimum of 150 ft from Minimum of 150 ft from drinking water wellsdrinking water wells

Minimum 10 ft downgradient Minimum 10 ft downgradient and 100 ft upgradient from and 100 ft upgradient from building foundations building foundations

Infiltration Basin Infiltration Basin Key Design CriteriaKey Design Criteria

Use a length to width Use a length to width ratio of at least 3:1ratio of at least 3:1

Grade basin bottom as Grade basin bottom as flat as possibleflat as possible

Side slopes not to Side slopes not to exceed 3:1exceed 3:1

Install pretreatment Install pretreatment device device (forebay/swale/filter strip)(forebay/swale/filter strip)

Design: Design: Infiltration Basin Infiltration Basin DepthDepth

Calculate ponding depth (d) Calculate ponding depth (d)

d = f * td = f * t Where:Where:

• f = percolation rate of surrounding soil (in/hr)f = percolation rate of surrounding soil (in/hr)• t = retention time (hr)t = retention time (hr)

72-hour maximum ponding time (24-hr 72-hour maximum ponding time (24-hr recommended)recommended)

Depth should be less than 2 feetDepth should be less than 2 feet

Design:Design: Infiltration Basin Infiltration Basin AreaArea

Calculate bottom area (A) Calculate bottom area (A)

A = 12 * V / (f * t), A = 12 * V / (f * t), Where Where

• V = volume to be infiltrated (ftV = volume to be infiltrated (ft33))V = WQv(ac-ft) * 43,560V = WQv(ac-ft) * 43,560

Design:Design: Infiltration Basin Infiltration Basin ExampleExample

Size an infiltration basin to treat a WQSize an infiltration basin to treat a WQVV of 0.15 ac-ft of 0.15 ac-ft

over 72 hours, if the surrounding soil percolation over 72 hours, if the surrounding soil percolation rate is 0.35 in/hrrate is 0.35 in/hr

d = (0.35 * 72) / 12 = 2.1 ftd = (0.35 * 72) / 12 = 2.1 ft Set d =Set d = 2.0 ft 2.0 ft t = 12 * d / f = 12 * 2.0 / 0.35 =t = 12 * d / f = 12 * 2.0 / 0.35 = 68 hours 68 hours A = (12 * 0.15 * 43560) / (0.35 * 68) = A = (12 * 0.15 * 43560) / (0.35 * 68) = 3,300 ft3,300 ft22

Infiltration Basin VegetationInfiltration Basin Vegetation

Plant native vegetation on side slopes and Plant native vegetation on side slopes and bottom of infiltration basinbottom of infiltration basin Can increase infiltration rateCan increase infiltration rate

Use plants listed in the BMP Manual Appendix A Use plants listed in the BMP Manual Appendix A “Recommended Plant Materials for BMPs”“Recommended Plant Materials for BMPs”

Select species that can withstand drought and Select species that can withstand drought and long periods of ponding long periods of ponding

DO NOT use sodDO NOT use sod

Infiltration Basin Infiltration Basin MaintenanceMaintenance

Inspect at least twice a year Inspect at least twice a year Initially inspect more frequently Initially inspect more frequently

Look for sustained pondingLook for sustained ponding Maintain vegetation Maintain vegetation Remove sedimentRemove sediment

Infiltration Basin MaintenanceInfiltration Basin Maintenance

Regular inspectionsRegular inspections Preferably once per monthPreferably once per month Assess length of time water is ponded following a Assess length of time water is ponded following a

stormstorm Stabilize areas of erosion in tributary areaStabilize areas of erosion in tributary area Remove trash and debris at beginning and end of Remove trash and debris at beginning and end of

wet seasonwet season Remove dry sediment from basin Remove dry sediment from basin

Use light equipment Use light equipment Wait until sediment Is cracking and readily Wait until sediment Is cracking and readily

separating from bottomseparating from bottom Weed trimming to maintain plantsWeed trimming to maintain plants

Infiltration TrenchInfiltration Trench

Infiltration Trench Plan ViewInfiltration Trench Plan View

Vegetated Channel

Infiltration Trench

Overflow

Bypass Structure

Pretreatment

Infiltration Trench Infiltration Trench PretreatmentPretreatment

Pretreatment

Infiltration Trench Infiltration Trench PretreatmentPretreatment

Pretreatment increases the life of the trenchPretreatment increases the life of the trench Remove as much of the suspended solids as Remove as much of the suspended solids as

possiblepossible Grit ChambersGrit Chambers Swales with check damsSwales with check dams Filters stripsFilters strips Sediment ForebaysSediment Forebays

Infiltration Trench Bypass & Infiltration Trench Bypass & OverflowOverflow

Overflow

Bypass Structure

Convey flows over Convey flows over the WQv around or the WQv around or over the trench over the trench safelysafely

Prevent erosionPrevent erosion

Infiltration Trench Infiltration Trench

Infiltration Trench

Infiltration TrenchInfiltration Trench

Designed to Infiltrate the WQv within 72 hours (24 Designed to Infiltrate the WQv within 72 hours (24 hours recommended)hours recommended)

Filled with clean stone 1.5-2.5 inches in diameterFilled with clean stone 1.5-2.5 inches in diameter Lined with filter fabricLined with filter fabric Under drain can be incorporated Under drain can be incorporated

Infiltration Trench Filter Infiltration Trench Filter FabricFabric

Use non-woven filter fabric layer close to the surface Use non-woven filter fabric layer close to the surface to prevent majority of substrate from getting clogged to prevent majority of substrate from getting clogged with sedimentwith sediment

Line the trench walls and bottom with filter fabricLine the trench walls and bottom with filter fabric

Infiltration Trench Infiltration Trench Monitoring WellMonitoring Well

Used to monitor the Used to monitor the infiltration rateinfiltration rate

Determine if trench Determine if trench needs cleaningneeds cleaning

4 to 6 inch diameter 4 to 6 inch diameter PVCPVC

Anchored to bottom of Anchored to bottom of trenchtrench

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OutletOutlet

Commercial Area DrainageCommercial Area Drainage

Riprap covered outlet

Overflow Weir

Infiltration Trench ExampleInfiltration Trench Example

Infiltration Trench ExampleInfiltration Trench Example

Portland OR (www.lowinpactdevelopment.org)

Infiltration Trench Design Infiltration Trench Design ConsiderationsConsiderations

Tributary area must be less than 5 acresTributary area must be less than 5 acres If runoff comes in as sheet flow orient the trench If runoff comes in as sheet flow orient the trench

perpendicular to the flowperpendicular to the flow If runoff is channelized orient the channel parallel If runoff is channelized orient the channel parallel

to the channelto the channel Don’t use limestone or shale as backfill materialDon’t use limestone or shale as backfill material Surrounding soil should be less than 40% claySurrounding soil should be less than 40% clay

Design:Design: Infiltration Trench Infiltration Trench VolumeVolume

Calculate the volume of the trench (VCalculate the volume of the trench (VTRTR) )

VVTRTR = WQv / n = WQv / n

where:where:

WQv = water quality volume (ftWQv = water quality volume (ft33) ) n = void space in trench media (0.4 for clean n = void space in trench media (0.4 for clean

stone, 1.5-2.5in diameter)stone, 1.5-2.5in diameter)

Design:Design: Infiltration Trench Infiltration Trench AreaArea

Calculate bottom area (A) Calculate bottom area (A)

A = 12 * WQv / (f * t)A = 12 * WQv / (f * t)

where:where: WQv = water quality volume (ftWQv = water quality volume (ft33) ) f = percolation rate of surrounding soil (in/hr)f = percolation rate of surrounding soil (in/hr) t = retention time (hr)t = retention time (hr)

Design:Design: Infiltration Trench Infiltration Trench DepthDepth

Calculate trench depth (D) Calculate trench depth (D)

D = VD = VTRTR / A / A

where:where:

VVTRTR = volume of the trench (ft = volume of the trench (ft33)) A = area of the trench (ftA = area of the trench (ft22))

The depth should be 3 to 8 ftThe depth should be 3 to 8 ft

Infiltration Trench Design Infiltration Trench Design LengthLength

If WQv enters as sheet flow position the If WQv enters as sheet flow position the trench perpendicular to the flow trench perpendicular to the flow

If stormwater enters as channel flow orient If stormwater enters as channel flow orient parallel to flow parallel to flow

Maximize the length of the trench for both Maximize the length of the trench for both flow typesflow types

Design:Design: Infiltration Trench Infiltration Trench ExampleExample

Size an infiltration trench to treat a WQSize an infiltration trench to treat a WQVV of 0.15 of 0.15

ac-ft over 48 hours, if the surrounding soil ac-ft over 48 hours, if the surrounding soil percolation rate is 0.35 in/hrpercolation rate is 0.35 in/hr

VVTRTR = (0.15 ac-ft * 43,560) / 0.4 = = (0.15 ac-ft * 43,560) / 0.4 = 16,335 ft16,335 ft33

A = (12 * 0.15 * 43560) / (0.35 * 48) = A = (12 * 0.15 * 43560) / (0.35 * 48) = 4,667 ft4,667 ft22

Assuming a sheet flow width of 250ft Assuming a sheet flow width of 250ft

LLtrenchtrench = = 250ft250ft

WWtrenchtrench = 7,780/250 = = 7,780/250 = 19ft19ft

Infiltration Trench Infiltration Trench MaintenanceMaintenance

Regular inspectionsRegular inspections Preferably once per monthPreferably once per month Assess length of time water is ponded following a Assess length of time water is ponded following a

storm (monitoring well)storm (monitoring well) Stabilize areas of erosion in tributary areaStabilize areas of erosion in tributary area Remove trash and debris at beginning and end of Remove trash and debris at beginning and end of

wet seasonwet season

Infiltration Trench Infiltration Trench MaintenanceMaintenance

If sediment is visible in top layer, remove top If sediment is visible in top layer, remove top layer of stone, filter fabric and sediment layer of stone, filter fabric and sediment Wash stoneWash stone Reinstall filter fabric and washed stone Reinstall filter fabric and washed stone

If standing water persists for more than a few If standing water persists for more than a few daysdays Remove and clean or replace all stone aggregate Remove and clean or replace all stone aggregate Replace filter fabricReplace filter fabric

Pervious PavementPervious Pavement

Pervious PavementPervious Pavement

www.oregon.gov/ODOT/TD/TP_RES/docs/2006_NWTC/2C_Cahill.pdf

Pervious surface

Pervious Pavement TypesPervious Pavement Types

Permeable Permeable Interlocking Interlocking Concrete PaversConcrete Pavers

Concrete Grid Concrete Grid PaversPavers

Pervious ConcretePervious Concrete Pervious Asphalt Pervious Asphalt

Cast-in-PlaceCast-in-Place Plastic Turf Plastic Turf

ReinforcingReinforcing GeowebsGeowebs

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Pervious PavementPervious Pavement

Design to infiltrate the Design to infiltrate the WQvWQv

Concrete Promotions Demo

I’lan Park, Leawood KS

Pervious PavementPervious Pavement

AdvantagesAdvantages Reduce flooding potentialReduce flooding potential Can be more aesthetically pleasingCan be more aesthetically pleasing

DisadvantagesDisadvantages May cost moreMay cost more Can be a more uneven driving surface Can be a more uneven driving surface

Pervious PavementPervious Pavement

Cast-In-Place Concrete Cast-In-Place Concrete SlabsSlabs

Reinforced slab, suitable Reinforced slab, suitable for heavy loadsfor heavy loads

Poured on sitePoured on site

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Precast Concrete GridsPrecast Concrete Grids

Permeable Concrete Permeable Concrete pavers with void areas pavers with void areas separating piecesseparating pieces

Higher percentage of Higher percentage of permeable surfaces permeable surfaces

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Modular Unit PaversModular Unit Pavers

Pavers themselves are impermeable Pavers themselves are impermeable Porous material places in gaps between paversPorous material places in gaps between pavers

Concrete Promotions Demo

GeowebsGeowebs

Traditionally used for soil Traditionally used for soil stabilizationstabilization

Pervious Pavement Pervious Pavement ConsiderationsConsiderations

System must be able to sustain traffic loadSystem must be able to sustain traffic load 15% Void space with infiltration rates > 12in/hr15% Void space with infiltration rates > 12in/hr Subbase – 36 to 42% voids compacted at 95 Subbase – 36 to 42% voids compacted at 95

proctorproctor Subbase – ¾ inch clean rock with < 2% passing Subbase – ¾ inch clean rock with < 2% passing

#200 sieve#200 sieve A minimum subbase thickness of 8 inchesA minimum subbase thickness of 8 inches Use non-woven geotexile fabric between subbase Use non-woven geotexile fabric between subbase

and soiland soil Use a uniform grade material to maximize voidsUse a uniform grade material to maximize voids

Pervious Pavement Design Pervious Pavement Design CriteriaCriteria

Only use certified ready-mix companiesOnly use certified ready-mix companies Request certified contractor orRequest certified contractor or

Require test placement (4 ydRequire test placement (4 yd33) to verify mix and ) to verify mix and installation proceduresinstallation procedures

Do not use pervious pavements in areas where Do not use pervious pavements in areas where heavy trucks will turnheavy trucks will turn

2:1 impervious to pervious area is good rule of 2:1 impervious to pervious area is good rule of thumbthumb

Use an underdrain to dewater subbase for events Use an underdrain to dewater subbase for events greater than the water quality eventgreater than the water quality event

Design:Design: Pervious Pavement Pervious Pavement

Design volume (DDesign volume (Dvv) )

DDVV= WQ= WQvv / n / n

where WQwhere WQvv = volume (ft = volume (ft33))

n = void spacen = void space

Design:Design: Pervious Pavement Pervious Pavement

Calculate the minimum required surface area Calculate the minimum required surface area (SA(SAminmin) to infiltration the WQv into the soil) to infiltration the WQv into the soil

SASAminmin = 12 * WQv / (f * t) = 12 * WQv / (f * t)

where:where:• WQv = water quality volume (ftWQv = water quality volume (ft33) ) • f = percolation rate of surrounding soil (in/hr)f = percolation rate of surrounding soil (in/hr)• t = retention time (hr)t = retention time (hr)

Design: Design: Pervious Pavement Pervious Pavement ExampleExample

Size a permeable pavement parking area to Size a permeable pavement parking area to capture and infiltrate a WQcapture and infiltrate a WQvv 0f 1.37 inches over a 0.5 0f 1.37 inches over a 0.5

acre tributary areaacre tributary area Assume 100% impervious tributary areaAssume 100% impervious tributary area Short-cut MethodShort-cut Method

WQv = (1.37in)*(0.05+0.009(100%)) = WQv = (1.37in)*(0.05+0.009(100%)) = 1.3in1.3in

Water quality volume to be infiltrated in 12 hrs into Water quality volume to be infiltrated in 12 hrs into subsurface soils with infiltration rate of 0.35 in/hrsubsurface soils with infiltration rate of 0.35 in/hr

Design: Design: Pervious Pavement Pervious Pavement ExampleExample

Using the previous example: WQv = 1.3inUsing the previous example: WQv = 1.3in

WQv (1.3 / 12)*0.5*43,560 = WQv (1.3 / 12)*0.5*43,560 = 2,360ft2,360ft33

DDVV = 2,360 ft = 2,360 ft33 / 0.4 = / 0.4 = 5,899 ft5,899 ft33

SASAminmin = 12 * 2,360 ft = 12 * 2,360 ft33 / (0.35 in/hr * 12 hrs)= / (0.35 in/hr * 12 hrs)= 6,742 ft6,742 ft22

6,742 ft6,742 ft22 / 43,560 = / 43,560 = 0.15 ac0.15 ac ( < 2:1 ratio) ( < 2:1 ratio)

Depth for the WQv = 5,899 ftDepth for the WQv = 5,899 ft33 / 6,742 ft / 6,742 ft22 = = 0.88 ft0.88 ft

Pervious Pavement Pervious Pavement MaintenanceMaintenance

Stabilize areas of erosion in tributary areaStabilize areas of erosion in tributary area

Don’t salt the 1Don’t salt the 1stst year year

Street sweeping with vacuum truckStreet sweeping with vacuum truck 3 times per year3 times per year

April, July, and NovemberApril, July, and November

Inspect underdrain outlets annuallyInspect underdrain outlets annually

Snow plowing acceptable but need to educate Snow plowing acceptable but need to educate operatorsoperators

Pervious Pavement Pervious Pavement ResourcesResources

Center for Transportation Research and Center for Transportation Research and Education, Iowa State UniversityEducation, Iowa State University

• www.ctre.iastate.eduwww.ctre.iastate.edu

Concrete PromotionsConcrete Promotions• www.concretepromotion.comwww.concretepromotion.com

Univeristy of Missouri – Kansas CityUniveristy of Missouri – Kansas City John Kevern, Ph.D. John Kevern, Ph.D.

BMP Subcommittee Update this GuidanceBMP Subcommittee Update this Guidance

Design Phase

– Erosion and sedimentation controls– Post-construction BMPs– Flood control improvements

Construction Phase

– Inspect and maintain BMPs for construction activities

– Construct Post Construction BMPs

– Maintain agreements for post-construction BMPs

DesignerDesigner

Planning Phase

– Environmental Site Assessment– Select Post Construction BMPs– Flood Control Study– Establish Long-term Maintenance Agreements

Review Team

PlanningEngineering

Parks & RecreationEnvironmental Specialists

Attorney Review Team

PlanningEngineering

Parks & RecreationEnvironmental SpecialistsOperations & Maintenance

Review Team

PlanningEngineering

Code ComplianceInspectors

Plat Approval

Occupancy Permit

Building Permit

Questions?Questions?

Comments.Comments.

Thank YouThank You