eric strecker3

1

1

Eric W. Strecker, [email protected]

Overview of Unit Processes Approach for BMP Selection and

Design

BMP Overview

Overview of Unit Processes Approach for BMP Selection and

Design

BMP Overview

2

Dry Extended Detention BasinsDry Extended Detention Basins

3 4

5 6

Dry Extended Detention Basins (cont.)Dry Extended Detention Basins (cont.)

DescriptionPonds without a permanent pool of water that are designed to detain the runoff from a water quality design storm and completely drain within 36 - 72 (typically 48) hours

DescriptionPonds without a permanent pool of water that are designed to detain the runoff from a water quality design storm and completely drain within 36 - 72 (typically 48) hours

Flood control potentialRecreational multi-use potentialHydromodification control potential

2

7


Major Treatment ProcessesFlow attenuationSome volume reductionSedimentationSome aeration / volatilization

Primary Pollutants RemovedSedimentParticulate-bound nutrients and metalsPetroleum hydrocarbons

Major Treatment ProcessesFlow attenuationSome volume reductionSedimentationSome aeration / volatilization


8


Critical Design ParametersStorage capacity (including sediment)Length-to-width ratioStage-discharge relationship (outlet design)Flow rate diversion for off-line facilities

Critical Design ParametersStorage capacity (including sediment)Length-to-width ratioStage-discharge relationship (outlet design)Flow rate diversion for off-line facilities

9


Max Elevation of Extended Detention Pool Emergency

Spillway

Outfall

Low Flow Channel

Sediment Forebay

Inflow

Maintenance Access Rd

Safety Bench

10


Outfall Erosion Protection

Embankment

Riser Pipe

Forebay

Influent Pipe

WQ Elevation

11


Forebay

Influent Pipe Overflow Spillway

Flood Control

Water Quality Control

Hydromodification ControlEnergy Dissipation

Energy Dissipation

Critical Flow Outlet Pipe

Infiltration

Multi-Stage Orifice Outlet Structure

Vegetated Low-flow Channel

Combination Facility

Forebay

Flood Control

Water Quality Control

Hydromodification Control

Infiltration

Perforated Riser Pipe Outlet Structure

Vegetated Low-flow Channel

Energy Dissipation

12

Dry Extended Detention Basins (cont.)Outlet Design

25-yr Outlet Design

2-yr Design Outlet

Emergency Spillway

Perforated Riser Water Quality Outlet

3

13

Routine Maintenance ActivitiesTrash and debris removalSediment removal from inlet/forebay and outletVegetation upkeep (e.g. mowing and pruning), removal of woody vegetation and noxious weedsVector controlPump or valve maintenanceFrequencies dictated by condition of pond (monthly, quarterly, or annually)

Routine Maintenance ActivitiesTrash and debris removalSediment removal from inlet/forebay and outletVegetation upkeep (e.g. mowing and pruning), removal of woody vegetation and noxious weedsVector controlPump or valve maintenanceFrequencies dictated by condition of pond (monthly, quarterly, or annually)


14

Infrequent Maintenance ActivitiesSediment removal from main pond areaBank or berm stabilization/erosion repair, if neededEnergy dissipator repairRegrading and revegetationFrequency dictated as needed (10 – 20 years)

Infrequent Maintenance ActivitiesSediment removal from main pond areaBank or berm stabilization/erosion repair, if neededEnergy dissipator repairRegrading and revegetationFrequency dictated as needed (10 – 20 years)


15

Vegetated SwalesVegetated Swales

16

Vegetated Swales (cont.)Vegetated Swales (cont.)

DescriptionShallow, open channels with low-lying vegetation covering the side slopes and bottom.

DescriptionShallow, open channels with low-lying vegetation covering the side slopes and bottom.

Easily integrated into site landscaping Perfect application for roadsCan potentially replace storm drain infrastructureSome hydromodification control potential

17


Major Treatment ProcessesFiltrationSome volume reduction (infiltration)Some sedimentationSome soil adsorption and plant uptake




18


Critical Design ParametersHydraulic retention timeMinimum lengthMaximum widthFlow rate, velocity, & depthSlope

Critical Design ParametersHydraulic retention timeMinimum lengthMaximum widthFlow rate, velocity, & depthSlope

4

19

Check Dam

Outlet

Inlet

Flow Spreader

Roadway

Energy Dissipater

Low-flowUnderdrain

Side Slope


20


Bottom Width(recommended 2 ft min,channel divider if >10ft)

Roadway Surface

Topsoil / Mulch

Water Quality DepthFlood Flow Depth

Grass height exceeds design flow by 2”

Freeboard

Shoulder

Swale Vegetation:Small plants, tall grasses and

shrubs

Underdrain if slope < 1.5%

21

Routine Maintenance ActivitiesTrash and debris removalVegetation upkeep (e.g. mowing, pruning) and removal of noxious weedsVector control

Infrequent Maintenance ActivitiesSediment removal at inletRegrading and revegetation if erosion occurs or standing water is presentUnderdrain clean out or replacement (if present)


Infrequent Maintenance ActivitiesSediment removal at inletRegrading and revegetation if erosion occurs or standing water is presentUnderdrain clean out or replacement (if present)


22

Filter StripsFilter Strips

Source: Caltrans

23

Filter Strips (cont.)Filter Strips (cont.)

DescriptionMildly sloping vegetated slopes that receive sheet flow runoff from adjacent impervious surfaces.

DescriptionMildly sloping vegetated slopes that receive sheet flow runoff from adjacent impervious surfaces.

Easily integrated into existing landscapingApplicable to roads and parking lots

24






5

25


Critical Design ParametersSheet flow retention timeMinimum lengthFlow rate, velocity, & depth

Critical Design ParametersSheet flow retention timeMinimum lengthFlow rate, velocity, & depth

26


Pavement Surface

Flow Spreader (gravel) Filter Strip

Topsoil / Compost Mix

Length “L”1’ Min

Collector Ditch / Swale

Optional trench drain or perforated underdrain

27


Filter Strip

Flow Spreader Extending Entire Length of Pavement

Collector Ditch/ Storm Drain

Pavement Surface 150’ Max Recommended

Filter Strip Length “L”

1’ Min.

Width “W”

28

Filter Strip (cont.)Filter Strip (cont.)

Pavement

Compost / Mulch Mix

Perforated underdrain pipe

Grass/vegetation

Filter fabric

Gravel backfill; depth depends on storage requirements

Gravel trench in no-vegetation zone

Enhanced Filter Strip / Bioslope

Source: Low Impact Development Center

29


Infrequent Maintenance ActivitiesSediment removalRegrading and revegetationUnderdrain clean out or replacement (if present)


Infrequent Maintenance ActivitiesSediment removalRegrading and revegetationUnderdrain clean out or replacement (if present)


30

BioretentionBioretention

6

31

Bioretention (cont.)Bioretention (cont.)

32


33


DescriptionVegetated (i.e., landscaped) shallow depressions with amended soils that retain, infiltrate, and evapotranspire runoff.

DescriptionVegetated (i.e., landscaped) shallow depressions with amended soils that retain, infiltrate, and evapotranspire runoff.

Easily integrated into site landscapingSome recreational multi-use potentialHydromodification control potential

34


Major Treatment ProcessesFiltration and sedimentationVolume reduction (infiltration & evapotranspiration)Soil adsorption and plant uptakeMicrobial decomposition

Primary Pollutants RemovedSedimentNutrients (total and some dissolved nitrogen and phosphorus)Metals (total and some dissolved)Petroleum hydrocarbonsPathogens

Major Treatment ProcessesFiltration and sedimentationVolume reduction (infiltration & evapotranspiration)Soil adsorption and plant uptakeMicrobial decomposition

Primary Pollutants RemovedSedimentNutrients (total and some dissolved nitrogen and phosphorus)Metals (total and some dissolved)Petroleum hydrocarbonsPathogens

35


Critical Design ParametersPonding depthEngineered soil depth and specificationPresence or absence of an underdrainNative soil infiltration rate if no underdrain present

Critical Design ParametersPonding depthEngineered soil depth and specificationPresence or absence of an underdrainNative soil infiltration rate if no underdrain present

36


Overflow Catch Basin

Parking Lot Sheet Flow

Curb Stops

Outlet

Underdrain Collection System

Stone Diaphragm

Optional Sand Layer

Grass Filter Strip

Gravel Curtain Drain Overflow

7

37


Gravel Curtain Drain

Optional Sand Filter Layer

Curb StopStone Diaphragm

Underdrain Bioretention Soil Media

38


Infrequent Maintenance ActivitiesSediment removalRegrading and revegetationUnderdrain clean out or replacement


Infrequent Maintenance ActivitiesSediment removalRegrading and revegetationUnderdrain clean out or replacement


39

Buckman Heights Apartments

Buckman Heights Apartments

40

Buckman Heights ApartmentsBuckman Heights Apartments

41

Apartment Courtyard Biofiltration System

Apartment Courtyard Biofiltration System

Runoff is directed to center planter and either infiltrates or overflows into small inlets

42Figure I.6.12

Buckman Heights ApartmentsBuckman Heights Apartments

8

43

Hydrological Source Control –Stormwater Planter Boxes

Hydrological Source Control –Stormwater Planter Boxes

44

Portland Ultra Urban Biofiltration

Portland Ultra Urban Biofiltration

45 46

47

Portland Version of Green StreetsPortland Version of Green Streets

48

Portland Version of Retro-fit Green StreetsPortland Version of Retro-fit Green Streets

9

49

Planting/Storage MediaPlanting/Storage Media

The planting media placed in the cell shall be highly permeable and high in organic matter (e.g., loamy sand mixed thoroughly with compost amendment) and a surface mulch layer.Planting media shall consist of 60 to 70% sand, 15 to 25% compost, and 10 to 20% clean topsoil. The organic content of the soil mixture should be 8% to 12%; the pH range should be 5.5 to 7.5.Sand should be free of stones, stumps, roots or other similar objects larger than 5 millimeters, and have the following gradation:

The planting media placed in the cell shall be highly permeable and high in organic matter (e.g., loamy sand mixed thoroughly with compost amendment) and a surface mulch layer.Planting media shall consist of 60 to 70% sand, 15 to 25% compost, and 10 to 20% clean topsoil. The organic content of the soil mixture should be 8% to 12%; the pH range should be 5.5 to 7.5.Sand should be free of stones, stumps, roots or other similar objects larger than 5 millimeters, and have the following gradation:

Particle Size (ASTM D422) % Passing

#4 100 #6 88-100 #8 79-97 #50 11-35 #200 5-15

50

Planting/Storage MediaPlanting/Storage Media

Compost should be free of stones, stumps, roots or other similar objects larger than ¾ inches; have a particle size of 98% passing through ¾” screen or smaller; and meet the following characteristics:Soluble Salt Concentration: < 10 mmhos/cm (dS/m)pH: 5.0-8.5Moisture: 30-60% wet weight basisOrganic Matter: 30-65% dry weight basisStability (Carbon Dioxide evolution rate): >80% relative to positive controlMaturity (Seed emergence and seedling vigor): >80% relative to positive controlPhysical contaminants: < 1% dry weight basis

Compost should be free of stones, stumps, roots or other similar objects larger than ¾ inches; have a particle size of 98% passing through ¾” screen or smaller; and meet the following characteristics:Soluble Salt Concentration: < 10 mmhos/cm (dS/m)pH: 5.0-8.5Moisture: 30-60% wet weight basisOrganic Matter: 30-65% dry weight basisStability (Carbon Dioxide evolution rate): >80% relative to positive controlMaturity (Seed emergence and seedling vigor): >80% relative to positive controlPhysical contaminants: < 1% dry weight basis

Importance of “Engineering” the SoilsImportance of “Engineering” the Soils

51 52

53

Vegetated Roofs – Detention and EvapotranspirationVegetated Roofs – Detention and Evapotranspiration

Gap World Headquarters, San Bruno, CA

Parking Garage, Oakland, CA

54

City of Portland -Simplified ApproachCity of Portland -Simplified Approach

10

55 56

57

Hamilton Ecoroof westside rainfall and runoffJune 28-29, 2002 storm event 0.73“

Hamilton Ecoroof westside rainfall and runoffJune 28-29, 2002 storm event 0.73“

-20

0

20

40

60

80

100

0

Time - hours

Gal

lons

Rain

Flow

Total catchment 3,692 sf, ecoroof 2,690 sf, * impervious surfaces 527 sf, pavers on sand base 475 sf *If the 239 gallons of rainfall from the impervious surfaces is removed then no runoff would have occurred

Total catchment 3,692 sf, ecoroof 2,690 sf, * impervious surfaces 527 sf, pavers on sand base 475 sf *If the 239 gallons of rainfall from the impervious surfaces is removed then no runoff would have occurred

Hydrological Source Control-

ET Losses

58

Portland RoofPortland Roof

59

Infiltration FacilitiesInfiltration Facilities

Source: Wisconsin Department of Natural Resources

Source: Low Impact Development Center

Infiltration Basin

Infiltration Trench

60

Infiltration Facilities (cont.)Infiltration Facilities (cont.)

Source: Portland Bureau of Environmental Services

11

61

WetpondsWetponds

Source: UDFCD 62

Stormwater WetlandsStormwater Wetlands

63

Stormwater Wetlands (cont.)Stormwater Wetlands (cont.)

DescriptionConstructed, natural treatment system consisting of a sediment forebay and permanent micro-pools with aquatic vegetation covering a significant portion of the basin.

DescriptionConstructed, natural treatment system consisting of a sediment forebay and permanent micro-pools with aquatic vegetation covering a significant portion of the basin.

Flood control potentialRecreational multi-use potentialHydromodification control potential

64


Major Treatment ProcessesSedimentation (incl. natural flocculation)Microbial decomposition/transformationSome volume reduction (evapotranspiration)Soil adsorption and plant uptake

Primary Pollutants RemovedCoarse and fine sedimentTotal and dissolved metals Nutrients, but may also be a source during dormant periods if the plants are not cut backPetroleum hydrocarbons

Major Treatment ProcessesSedimentation (incl. natural flocculation)Microbial decomposition/transformationSome volume reduction (evapotranspiration)Soil adsorption and plant uptake

Primary Pollutants RemovedCoarse and fine sedimentTotal and dissolved metals Nutrients, but may also be a source during dormant periods if the plants are not cut backPetroleum hydrocarbons

65


Critical Design ParametersRetention timeDepth distributionLength to width ratioBase flow

Critical Design ParametersRetention timeDepth distributionLength to width ratioBase flow

66


Shallow water with emergent Cattails Shallow water with

emergent Bulrush

Open water areas

Inlet

Outlet structure

Open water pool, depth = 4-6 ft.

Shallow water depth = 1-2 ft

Small storm water quality pool, depth ~3-4 ft.

12

67


Routine Maintenance ActivitiesTrash and debris removalPerimeter landscape maintenanceVector control

Infrequent Maintenance ActivitiesSediment removal from inlet and outletRemoval of algal mats and control of fringe vegetation

Routine Maintenance ActivitiesTrash and debris removalPerimeter landscape maintenanceVector control

Infrequent Maintenance ActivitiesSediment removal from inlet and outletRemoval of algal mats and control of fringe vegetation

68

Sand FiltersSand Filters

Source: UDFCD

69

Sand Filter (cont.)Sand Filter (cont.)

DescriptionBasin or vault system with a thick sand filter bed and an extensive underdrain.

DescriptionBasin or vault system with a thick sand filter bed and an extensive underdrain.

Recreational multi-use potential

70

Sand Filters (cont.)Sand Filters (cont.)

Major Treatment ProcessesFiltrationSome adsorptionSome surface sedimentation

Primary Pollutants RemovedCoarse and fine sedimentParticulate-bound metals, nutrients, and pathogensPetroleum hydrocarbons

Major Treatment ProcessesFiltrationSome adsorptionSome surface sedimentation

Primary Pollutants RemovedCoarse and fine sedimentParticulate-bound metals, nutrients, and pathogensPetroleum hydrocarbons

71


Critical Design ParametersMaximum emptying timeMedia depth and particle gradationUnderdrain flow capacity

Critical Design ParametersMaximum emptying timeMedia depth and particle gradationUnderdrain flow capacity

72


Routine Maintenance ActivitiesTrash and debris removalSurface scraping (top 2 to 4 inches)Vector Control

Infrequent Maintenance ActivitiesVegetation managementSand replacementUnderdrain clean out or replacement

Routine Maintenance ActivitiesTrash and debris removalSurface scraping (top 2 to 4 inches)Vector Control

Infrequent Maintenance ActivitiesVegetation managementSand replacementUnderdrain clean out or replacement

13

73


Recreational Multi-Use Sand Filter

74

Cartridge FiltersCartridge Filters

StormFilter™™

CDS Media Filtration System Source: CDS Technologies, Inc.

75

Hydrodynamic SeparatorsHydrodynamic Separators

CDS UnitSource: CDS Technologies, Inc.

VortechnicsSource: Stormwater 360o, Inc.

76

Proprietary BiotreatmentProprietary Biotreatment

Filterra®®

Source: AmericastSource: Americast

StormTreat™™Source: StormTreat System, Inc.Source: StormTreat System, Inc.

77 78

Low Impact DevelopmentExample Project OverviewLow Impact DevelopmentExample Project Overview

New club house and restaurant and relocation of the golf course operationsA new hotel, restaurant, & spa located where existing club house and golf operations areaTourist-serving fractionalized ownership condominiums

New club house and restaurant and relocation of the golf course operationsA new hotel, restaurant, & spa located where existing club house and golf operations areaTourist-serving fractionalized ownership condominiums

ReRe--development and New Developmentdevelopment and New Development

14

79

Client Specified Desired Project Water Quality and Hydrology Goals

Client Specified Desired Project Water Quality and Hydrology Goals

No changes in pre/post in hydrology

No increase in runoff volume

No increase in infiltrationShow an improvement in water quality

No irrigation runoff

Eliminate all runoff to Morning Canyon

No changes in pre/post in hydrology

No increase in runoff volume

No increase in infiltrationShow an improvement in water quality

No irrigation runoff

Eliminate all runoff to Morning Canyon

80

Why These Goals?Why These Goals?

Project drains to a State defined “Area of Special Biological Significance” – Crystal Cove

Morning Canyon has had erosion problems from increased runoff

Seeps downstream of the site are a concern

Client wanted quick permitting process and environmental community acceptance

Project drains to a State defined “Area of Special Biological Significance” – Crystal Cove

Morning Canyon has had erosion problems from increased runoff

Seeps downstream of the site are a concern

Client wanted quick permitting process and environmental community acceptance

81

No Change in Hydrology!No Change in Hydrology!

Manage the “ET” Sponge

Necessitated a detailed analysis of precipitation, runoff, shallow soil soaking and drying, and deeper infiltration

to ascertain what conditions to match

Manage the “ET” Sponge

Necessitated a detailed analysis of precipitation, runoff, shallow soil soaking and drying, and deeper infiltration

to ascertain what conditions to match

82

Pre- and Post-Hydrology No BMPsPre- and Post-Hydrology No BMPs

Water BalanceExisting Conditions

12%

83%

5%

Water Balance Developed Conditions

51%46%

3%

Runof f Evap & Trans Groundw ater

About 83% Evapotranspiration

Pre-Development!

83

Evaluated “Standard” LID ApproachEvaluated “Standard” LID Approach

How much of the site would we have to have in biofiltration areas to meet goals?

With:Various depths of amended, moisture holding soils and

Limited infiltration.

Result: 30% of site would have to be in bioswales to meet project goals!

How much of the site would we have to have in biofiltration areas to meet goals?

With:Various depths of amended, moisture holding soils and

Limited infiltration.

Result: 30% of site would have to be in bioswales to meet project goals!

84

stormwater treatment system includes:

Biofiltration

Cisterns to capture runoff from all developed areas of the project of the equivalent of 1.26” of rainfall over the project impervious areas.

Use of the irrigation storage reservoirs to store the cistern outflow from all area of the Project

Plan BPlan B

15

85

What to do with

the water?

What to do with

the water?

Golf Golf CourseCourse

(of (of course)!course)!

86

Water Balance for All Years ModeledWater Balance for All Years Modeled

Water Balance w/ 10 Day Cisterns & Reservoirs

6.23

113.91

2.94

Water BalanceExisting Conditions

7.22

50.65

3.49

Water Balance Developed Conditions

32.27

88.06

2.74

Runof f Evap & Trans Groundw ater

87

Average Annual TSS & Nutrient Loads Average Annual TSS & Nutrient Loads

Modeled Constituent - Loads TSS TP TKN Nitrate-N

Modeled Area Site Conditions

(tons) (lbs) (lbs) (lbs)

Existing 0.903 6.30 48.5 10.6

Developed w/o PDFs 2.51 25.7 197 32.6

Dev w/ PDFs 0.410 4.94 33.8 7.02

Pelic

an P

oint

Pro

ject

A

rea

(49.

7 ac

res)

% Change -55% -22% -30% -34%

88

SummarySummaryLow Impact Development Techniques Can Reduce hydrological changes

Possible to match pre-development surface hydrology

More difficult if desire is to match surface and sub-surface hydrology

EPA and other manuals have oversold some of the benefits based upon flood design hydrology approach used to estimate hydrological performance

Low Impact Development Techniques Can Reduce hydrological changes

Possible to match pre-development surface hydrology

More difficult if desire is to match surface and sub-surface hydrology

EPA and other manuals have oversold some of the benefits based upon flood design hydrology approach used to estimate hydrological performance

89

ConclusionsConclusions

eric strecker3

Technology

bmp selection

detainthe runoff

designbmp overvieweric

water qualitydesign

permanent pool ofwater