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Surviving the Transition to Environmental Site Design in Maryland
ESD Practices and Tools to Verify On-site Compliance
May 13, 2010Brought to you by the Chesapeake Bay Trust and the
U of MD Mid-Atlantic Water Program
Webcast Agenda
1. Why ESD is Important to the Bay
2. The New Design Sequence and Spreadsheet
3. Using Alternative Surfaces and Credits
4. Design of Micro- ESD Practices
5. Getting to Compliance
Speaker Info
Tom SchuelerChesapeake Stormwater Network
117 Ingleside AvenueBaltimore, MD 21228
Webcast Caveats & Ground Rules
The opinions in this webcast are exclusively those of CSN and do not necessarily reflect those of MDE
Check with your local reviewing authority for other differences
Redevelopment will not be covered today, but will be the focus of June 10 webcast
Still some gray areas, will produce a tech bulletin to resolve them based on your feedback today
No whining or wind-bagging
The Bay Stormwater Problem
Stream habitat and biodiversity degraded in 10,000 stream miles in the Bay watershed
Major ecological impacts in small estuaries and coastal creeks
Fastest growing nutrient load source in the Bay watershed
Bacteria violations in runoff close streams, beaches and shellfish beds Pesticides detected in 95% of
urban streams and fish tissues sampled
Metals, PCBs and hydrocarbons in tidal sediments
Our traditional stormwater practices have not solved these problems
The New Maryland ESD Regulations
You are not alone..tougher stormwater regulations are on the horizon in all Bay states: See Resource 1
Maximum Extent Practicable is defined as maintaining predevelopment site runoff to “woods in good condition.” The resulting ESD volume typically ranges between 1.7 and 2.6 inches, depending on soils and development intensity
Features of the CSN ESD to MEP Compliance Spreadsheet
Automatically Calculates ESD Target Volume
Accounts for all of the credits, alternative surfaces, micro-ESD practices and conventional practices in a step-wise fashion
Simultaneously tracks ESD volume and Critical Area 10% requirements
Easy to verify compliance
Status of Compliance Spreadsheet
Spreadsheet and Users Guide are provided in Resources 2 and 3
This is a test version for review Other spreadsheets have been developed Will produce “final” spreadsheet in June to
fix any bugs
Before You Get Started
Site Recon (understand the site) Environmental mapping (protected areas) Define small drainage areas and flow paths ID locations of most permeable soils Develop site plan that shows impervious
and pervious cover footprints
Site mapping and stormwater concept plans are mandated at the earliest stages of development plan review
Mapping Requirements
• Wetlands
• Major Water Ways
• Floodplains
• Critical Areas
• Wetland Buffers
• Perennial Streams
• Stream Buffers
• Forest Stand Delineation
• Steep slopes
• Springs and seeps
• Highly erodible soils
• Topography
• Existing drainage area
• Hydrologic Soil Groups
• Zero-order streams
CSN Tip: Its not just about what‟s off-limits
Step 1 ESD Site Planning Checklist
Must answer 12 questions related to ESD site and stormwater planning
Should be able to answer “Yes” or “does not apply”
Show on the site plan If answer is “No”, must provide a written
narrative as to why it could not have been used
.
ESD Implementation Checklist Check all of the Following ESD Practice That Were Implemented at Site Yes No N/A
Environmental Mapping Was Conducted at Site Prior to Layout XNatural Areas Were Conserved (e.g., forests, wetlands, steep slopes, floodplains)
X
Stream, Wetland and Shoreline Buffers Were Reserved XDisturbance of Permeable Soils Was Minimized XNatural Flow Paths Were Maintained Across the Site XBuilding Layout Was Fingerprinted to Reduce Clearing and Grading at Site XSite Grading Promoted Sheetflow From Impervious Areas to Pervious Ones
X
Site Design Was Evaluated to Reduce Creation of Needless Impervious Cover
X
Site Design Was Evaluated to Maximize Disconnection of Impervious Cover
X
Site Design Was Evaluated to Identify Potential Hotspot Generating Area for Stormwater Treatment
X
Erosion and Sediment Control Practices and Post Construction Stormwater Management Practices Were Integrated into a Comprehensive Plan
X
Tree Planting Was Used at the Site to Convert Turf Areas into Forest X
The basic idea is that a compliant plan is one without any no‟s (either a yes or not applicable)
Step 2 Calculate Site IC and WQv
Four Basic Inputs: Site Area Existing Site Impervious Cover Area Proposed Site Impervious Cover Area WQv Rainfall Depth (0.9 or 1.0)– Impervious cover is measured as any area
without vegetative or pervious cover
.
Step 2: Calculate Site Imperviousness and Water Quality Volume, WQv
Site Area, A (acres) 38
Existing Impervious Surface Area (acres) 0
Proposed Impervious Surface Area (acres) 13.8
Existing Imperviousness, Ipre 0.0%
Proposed Imperviousness, Ipost 36.3%
Development Category New Development
Rainfall Depth, P (in) 1.0
Runoff Coefficient, Rv 0.38
Water Quality Volume, WQv (ac-in) 14.32
Water Quality Volume, WQv (cf) 51,982
CSN Tip: Break sites up into 2 to 5 acre sub-drainage areas, define natural flow paths, and make best estimate of IC (and increase it by 15%)
Step 3 Compute MD Critical Area Phosphorus Removal Requirement *
Automatically calculates the phosphorus removal requirement, depending on whether the site is classified as new development or redevelopment (>15% IC)
.
* This requirement applies to Intensely Developed Areas in the 1000 ft Critical Area
Step 4Enter Pre-development Soil Data
Enter Percent Site Area in Hydrologic Soil Group A, B, C or D
Automatically computes ESD rainfall Target Volume, and the Recharge Volume
Your HSGs will determine your ESD strategy
.
% Soil Type A 0%
% Soil Type B 60%
% Soil Type C 40%
% Soil Type D 0%
Pre-Developed Condition, RCNwoods 61
New Development
Soil Type A ESD Rainfall Target, PE (in) 0.00
Soil Type B ESD Rainfall Target, PE (in) 1.08
Soil Type C ESD Rainfall Target, PE (in) 0.72
Soil Type D ESD Rainfall Target, PE (in) 0.00
Site ESD Rainfall Target, PE (in) 1.80
ESD Runoff Depth, QE (in) 0.68
ESD Runoff Volume, ESDv (cf) 93,567
Required Recharge Volume, Rev (ac-ft) 0.25
Required Recharge Volume, Rev (cf) 10,812
Output From Spreadsheet in this Step
Step 5 Select Alternative Surfaces
Look at areas at Site where Green Roof or Permeable Pavers Can be Used
Enter area and thickness The spreadsheet then reduces the ESD
Rainfall Target volume and adjusts the Phosphorus removal rate accordingly
.
Alternative Surfaces
Contributing
Drainage Area (ac) Thickness Effective RCN
Green Roof (on Soil Type A) 0
Green Roof (on Soil Type B) 0
Green Roof (on Soil Type C) 0
Green Roof (on Soil Type D) 0
Permeable Pavement (Soil Type A) 0
Permeable Pavement (Soil Type B) 0
Permeable Pavement (Soil Type C) 0
Alternative Surfaces: Permeable Pavements
Permeable PaverESD Sizing and Applicability
Effective RCNs for Permeable Pavements
Hydrologic Soil Group
Subbase A B C D
6” 76 84 93 ─
9” 62 65 77 ─
12” 40 55 70 ─
Design shall include overdrain (inv. 2” below pavement base)
If sub-base is greater than 12”or under drains are used on D soils, then skip this step, and enter as an upgraded BMP later on
MDE Guidance on Permeable Pavers
Not allowed on D soils or Fill Soils Porosity = 30% More than 10,000 sf = must have tested
infiltration rate of more than 0.52 in/hr Under-drain OK for smaller projects
CSN Tip: Detailed paver design spec available atwww.chesapeakestormwater.net
Paver Design ModificationEnhanced Filter
Source: Hunt and Collins, 2008
Enhanced Filters The stone reservoir volume is equal to the
surface area multiplied by depth divided by the porosity (n) of the stone
Used to address Rev for the contributing impervious area using the percent volume method.
When coupled with other properly designed structural or micro-scale practices, the combined system will address the ESD sizing criteria.
Reinforced Turf
Post development RCN‟s for reinforced turf applications should reflect the surfacing material used (e.g., “open space in good condition” for grass).
Alternative Surfaces: Green Roof
CSN Tip: Design spec available on CSN website –www.chesapeakestormwater.net
Green Roof Sizing
Only Used to Reduce Curve Number No direct reduction of ESD volume Rev must be provided separately
Effective RCNs for Extensive Green Roofs
Roof Thickness (in.): 2 3 4 6 8 Effective RCN: 94 92 88 85 77
Step 6Utilize Disconnection and Filtering
Credits
Three broad credits Rooftop Disconnection Non-rooftop Disconnection Expanded Conservation Area
Enter the CIDA (contributing impervious drainage area) and a few simple design parameters
Must also enter the predominant pre-development HSG of the filter path to compute the TP reduction
.
Step 6: Select Nonstructural Practices to Treat the ESD Rainfall Target
Nonstructural PracticesPE Credit
Description
Contributing
Impervious
Cover (ac)
Direct ESDv
Received by
Practice (cf)
ESDv
from
Upstream
Practices
(cf)
Practice Specific
Parameter(s)
PE
Credit
(in)
ESDv
credit
(cf)
Runoff
Volume
Remaini
ng (cf)
Enhance
d Filter
Volume
(cf)
Rev
(cf)
Disconnection of Rooftop
Runoff (A/B Soils)
Up to 1 inch credit
provided based upon
disconnection flow
length. 3 18,622 0
Flow Path (ft) East/West
1 10,346 8,276 10,34675
Western
Shore
Disconnection of Rooftop
Runoff (C/D Soils)
Up to 1 inch credit
provided based upon
disconnection flow
length. 0 0 0 0 0 0
Disconnection of Non-Rooftop
Runoff (A/B Soils)
Up to 1 inch credit
provided based upon
disconnection and
contributing flow
lengths. 0 0
Disconnection
Length (ft)
Contributing
Length (ft)
(Impervious)
0.4 0 0 075 150
Disconnection of Non-Rooftop
Runoff (C/D Soils)
Up to 1 inch credit
provided based upon
disconnection and
contributing flow
lengths. 0 0 0 0 0 0
Sheetflow to Conservation
Areas (A/B Soils)
Up to 1 inch credit
provided based upon
conservation area
width. 0 13437
Minimum
Width (ft)
1 7,465 -7,465 7,465100
CSN Tip: Connect CIDA “blobs” with pervious “blobs” on plan and check distances/slopes. OK to aggregate acceptable credits in the spreadsheet
Lots of opportunity to boost the hydrologic
function of urban turf through ESD Credits
Our Turf Is Not Very Pervious and is Ineffective in Treating Stormwater
• Top Soil is Stripped• Soil Structure is Lost• Subsoils are Compacted• Reduced Water Holding
Capacity • Low Infiltration Rate• High Nutrient
Concentrations• Runon to Impervious
Cover
MDE Simple Disconnection
Min. 15 feet length 10 feet lateral setback to IC Max Filter Path 0f 75 ft Max of 500 sf of IC per disconnect (1000 for non-
rooftop) Max 5% slope w/o infiltration berms A, B and C soils OK, soil amendments may be needed on
D soils or disturbed soils Flows shall be non-erosive for two year storm
Rooftop DisconnectionMDE Sizing and Applicability
Applies to all development types of low to moderate intensity
ESD Sizing Factors for Rooftop Disconnection
Disconnection Flow Path Length (ft.)
Western Shore 15 30 45 60 75
Eastern Shore 12 24 36 48 60
PE (in.) = 0.2 0.4 0.6 0.8 1.0
Disconnect to Grass Filter Strip ESD Sizing
Non-Rooftop Disconnection
Ratio of Disconnection Length to Contributing Length
Impervious Ratio 0.2:1 0.4:1 0.6:1 0.8:1 1:1
PE (in.) = 0.2 0.4 0.6 0.8 1.0
CSN Design Guidelines for Grass Filter Strip
Soil and Ground Cover Amended Soils and Dense Turf Cover
Construction Stage Prevent Soil Compaction by Heavy Equipment
Typical Application Treat Small Areas of Impervious Cover Close To Source (max of 5000 square feet)
Compost Amendments Yes
Boundary Spreader Gravel Diaphragm at Top of Filter Permeable Berm at toe of filter
Boundary Zone At 25 feet of level grass
Concentrated Flow? Not Recommended
Entrance Slope Less than 2% in first ten feet of strip
Maximum Overall Slope
5%
Sheet flow to Conservation Area (CA)
MDE Conservation Area Rules
Max Slope of 5% in CA Max IC length of 75 ft to CA CA must be at least 20,000 square
feet in area CA must have min. width of 50 ft No managed turf in CA
Sheetflow to Conservation Area Sizing Factors
Min. Width (ft) = 50 75 100
PE (in.) = 0.6 0.8 1.0
CSN Supplemental Guidelines for Conservation Filters
Soil and Ground Cover Undisturbed Soils and Native Vegetation
Construction Stage Located Outside the Limits of Disturbance and Protected by ESC Perimeter Controls
Typical Application Adjacent Drainage to Stream Buffer or Forest Conservation Area
Compost Amendments No
Boundary Spreader Infiltration Berm at Top of Filter
Boundary Zone 10 feet of Level Grass
Concentrated Flow? Runoff should enter the boundary as sheetflowfor the one-inch storm or use concrete engineered level spreader
Max Entrance Slope Less than 4% in the first ten feet of filter
Site Reconnaissance Site visit to confirm topography, slope, and soil conditions prior to design
Critical Area Buffer General rule is to keep stormwater treatment out of the
100 foot buffer OK to use bioretention and filter strip at boundary
Exceptions: Use of regenerative conveyance wetlands through the
buffer in zero-order streams or ditches Use bioretention or other practices with trees in
buffer exception areas ?
CSN Tip: Provide a Credit for Soil Restoration and
Reforestation
Examples of Qualifying Criteria
• Minimum area of 5000 sf
• Stormwater or conservation easement
• Long term forest plan
• Achieve 75% forest canopy in 10 years
• Show on all ESC drawings
Credits Are Easy to Show on Plan
But Will They Actually Show Up at the Site?
Four Stage Review:
1. Evaluate Feasibility During Concept Design
2. Confirm Area in Final Design
3. Protect During Construction inspection
4. Verify as Part of Final Stormwater Acceptance
Step 7Apply ESD Micro-Practices
100% IA to micro-practices Enter CIDA, and specific design
parameters for each micro-practice selected
Can select a downstream practice to which runoff will flow to
HSG are used to make sure that the Micro-practices are properly applied to the right soil, and adjust TP removal rate
.
The List of Micro-ESD Practices
Rainwater Harvesting Submerged Gravel Wetland Micro-Infiltration (Infiltration) Rain Garden * Micro-bioretention (Bioretention) * Landscape Infiltration Grass Swales Bioswales) (Dry Swales) * Wet Swales Enhanced Filters are add on to * practices
Micro practices should be used to achieve entire ESD volume, or at least the entire water quality volume
Step 7: Select Micro-Scale Practices to Treat the ESD Rainfall Target
Micro-Scale
Practices PE Credit Description
CDIA
(ac)
Direct ESDv
Received
by Practice
(cf)
ESDv
from Up
Practice
s (cf)
Practice Specific
Parameter(s) PE
ESDv
credit
(cf)
Enhance
d Filter
Volume
(cf) Rev (cf)
Downstream
Practice
Rainwater
HarvestingPE credit is based on design
volume 0 0
Design
Volume (cf)
0.00 0 0 0
Submerged
Gravel
WetlandsPE credit is based on design
volume 0 0
Surface Area
(sf) Depth* (ft)
0.00 0 0 02.2
Micro-
InfiltrationPE credit is based on design
volume 5 31,037 0
Surface Area
(sf) Depth* (ft)
1.02 17,600 13,437 17,600
Sheetflow to
Conservation Areas
(A/B Soils)11,000 1.6
Rain Gardens
(A/B Soils)PE = 10" x Surface Area /
Drainage Area 0 0
Surface Area
(sf)
0.00 0 0 0
Rain Gardens
(C/D Soils)PE = 10" x Surface Area /
Drainage Area 0 0 0 0.00 0 0 0
Bioretention
(A/B Soils)PE = 15" x Surface Area /
Drainage Area 5 31,037 0
Surface Area
(sf)
1.38 23,750 7,287 23,750
Grass Swales (A/B
Soils)20,000
Bioretention
(C/D Soils)PE = 15" x Surface Area /
Drainage Area 0 0 0.00 0 0 0
Landscape
InfiltrationPE = 20" x Surface Area /
Drainage Area 0 0
Surface Area
(sf)
0.00 0 0 00
Grass Swales
(A/B Soils)PE = 10" x Surface Area /
Drainage Area 0.8 4,966 7287
Surface Area
(sf)
0.49 3,325 1,641 3,3254,200
Grass Swales
(C/D Soils)PE = 10" x Surface Area /
Drainage Area 0 0 0 0.00 0 0 0
Bio-swales (A/B
Soils)PE = 15" x Surface Area /
Drainage Area 0 0
Surface Area
(sf)
0.00 0 0 00
Bio-swales (C/D
Soils)PE = 15" x Surface Area /
Drainage Area 0 0 0 0.00 0 0 0
Wet SwalesPE credit is based on design
volume 0 0
Surface Area
(sf) Depth* (ft)
0.00 0 0 00 1.0
It seems complex, but only a few inputs are needed
ESD PRACTICE HSG A HSG B HSG C HSG DPermeable Paver X X X
Rainwater Harvesting X X X X
Submerged Gravel Wetlands
X X
Micro-infiltration X X
Rain Garden X X X
Bioretention X X X
Landscape Infiltration X X
Grass Swales X X X
Bioswales X X X X
Wet Swales X X
Enhanced Filters X X
X= may be suitable depending on depth to water table, bedrock and slope
Your HSG‟s Determine Which Micro-Practices Are Feasible
Comparing the Micro-PracticesESD PRACTICE ESD
Efficiency Max
CDA (sf)Upgrade
Size?Rainwater Harvesting 20+ ~20,000 Yes
Gravel Wetlands ~10 < 1 acre No
Micro-infiltration 15 500 Yes
Rain Garden 10 2,000 No
Micro-Bioretention 15 20,000 Yes
Landscape Infiltration 20 20,000 No
Grass Swales 10 > 1 acre No
Bioswales 10 > 1 acre Yes
Wet Swales 15 > 1 acre ?
Enhanced Filters ~6 n/a No
An Example of ESD Upgrading
Landscape Infiltration
.
Four layer System
Surface ponding12 inch of planting soil 12 inch of gravel 12 inch of sand
Landscape Infiltration
Restricted to A & B soils Max CDA of 10,000 sf (w/o soil testing and
pretreatment)• This has the best ESD reduction of any
micro-ESD practice per square foot of practice surface area
.
Essentially an infiltrating bioretention facility w/o underdrain
Submerged Gravel Wetland
Submerged Gravel Wetland
C or D Soils High Water Tables and Eastern Shore Minimum CDA of 1 acre 18 to 48 inches of gravel Pretreatment required Updated design guidance available from
UNH as Resource 5
Submerged Gravel Wetland Sizing
PE for the contributing drainage area is based on the volume captured by submerged gravel wetlands.
Assume about 10 inches
Dry Well = Micro-infiltration
Dry-Well (Micro-Infiltration) ESD Sizing
A PE value based on the ESDv captured and treated shall be applied to the contributing drainage area.
The storage area for the ESDv includes the sand and gravel layers in the bottom of the facility.
Assume about 15 inches
Dry Well = Micro-infiltration
A and B Soils Max CDA of 500 sf Above this shift to normal infiltration
trench design Pretreatment Bottom sand layer 10 feet setback from foundations
Rainwater Harvesting
Rainwater HarvestingESD Sizing and Applicability
Not a lot of design constraints Spreadsheet available to determine the
ESD volume actually captured based on indoor and outdoor demand
Rain barrels and cisterns shall be designed to capture at least 0.2 inches of rainfall from the contributing rooftop area.
A PE value based on the ESDv captured and treated shall be applied to the contributing rooftop area.
Micro-Bioretention
CDA should not exceed 0.5 acres Must store at least 75% of ESDv OK for all soil types Temp ponding of 12 inches Filter bed between 2 and 4 feet deep
Rain Garden
Rain-gardens CDA should not exceed
2000 sf (residential) 10,000 sf (other applications)
Must store at least 75% of ESDv Preferred for A & B Soils Restricted for C & D Soils Temp ponding of 6 inches Filter bed between 12 and 18 inches deep No underdrain
Grass Channels
At least its not a credit anymore!
ESD Sizing for Grass Channels
The maximum flow velocity for the ESDv shall be less than or equal to 1.0 fps.
Grass Channels
OK for A, B & C Soils For roads not parking lots Swale length = road length Max slope of 4% * Max ESD flow depth of 4 inches Checkdams or infiltration berms Swale bottom at least 2% of CDA* Max CDA of 1 acre *
* applies to all three designs
CSN Design Guidelines for Grass Channel
1. Explicitly prohibit for parking Lots
2. Minimum bottom width of 4 feet
3. One foot of restored soil along channel bottom required for C and D soils and mass graded B soils
4. No more than 3% slope in any 50 foot segment (low check dams)
5. May need initial biodegradable geo-fabric
6. Be non-erosive for 10 year storm
Wet Swales For C and D Soils Non-residential applications Useful in flat terrain with high water table
Wet SwaleSizing
Wet swales shall be designed to store at least 75% of the ESDv.
A PE value equivalent to the volume captured and treated shall be applied to the contributing drainage area.
Assume about 8 to 12 Inches
CSN Wet Swale Design Criteria
1. Average dry weather ponding depth no more than 6 inches
2. Max. dry weather ponding of 18 inches
3. Multiple cell system, at least every 50 ft
4. Wetland planting plan (emergent or forested)
5. Have hydraulic capacity for 10 year storm
Bio-Swales = Dry Swales
Bio-Swale ESD Sizing and Applicability
OK for all soil types Follow standard swale criteria Surface area 2% of CDA
Questions and Answers
Step 8Check for ESD Compliance and Go Back
Minimum ESD For Full WQv Entire Rev Zero TP removal requirement
Must Attempt to Provide ESD for Full ESD Target Volume .
ESDv Treated (cf) 62,485 Total Rev (cf) 62,485
PE achieved (inches) 1.20
WQv Requirements Met Through Environmental Site Design? YES
WQv Remaining? (cf) 0
Entire ESDv Treated Through Environmental Site Design? NO
ESDv Remaining? (cf) 31,082
Rev Requirements Met Through Environmental Site Design? YES
Rev Remaining? (cf) 0
Several iterations are needed to get too compliance
Strategies to Achieve Compliance
Adjust site layout to reduce IC or increase forest cover. Make sure that all the „No‟s “ are addressed
Consider more alternative surfaces (most designers will have skipped this step initially)
Expand site area subject to credits (e.g., more disconnection, improve soil and slope conditions within filter strip, accept concentrated flows w/ level spreader)
Strategies to Achieve Compliance (continued)
Add more Micro-ESD practices to pick up addl. untreated CIDA
Change ESD practices to get higher runoff reduction (e.g., go from grass channel to bio swale, or from rain garden to micro-bioretention
Add an Enhanced Filter to the bottom of select micro-ESD Practices
Strategies to Achieve Compliance (continued)
UPGRADE: Substitute Larger ESD practices such as Bioretention, Dry Swales and Infiltration that pick up more CIDA or have higher runoff reduction
Do more soil infiltration testing to find best sites
ESD basins Use bioretention within ED or flood control pond (at smaller sites)
Subarea Over-control As long as they drain to same area, OK to over control in one DA to compensate for under-control in another
Step 9 Compute reduced RCN for CPvCalculations
Automatically calculates a new runoff curve number (RCN) to calculate the remaining storage volume needed for channel protection that reflects the final combo of ESD practices employed.
The RCN can also be used in hydrologic models for peak discharge calculation
. Reduced RCN for Type A Soils 42
Reduced RCN for Type B Soils 63
Reduced RCN for Type C Soils 77
Reduced RCN for Type D Soils 81
Composite Reduced RCN 69
Q (in) 0.45
CPv Treatment Required (cf) 62,511
Step 10Apply Structural Practices for
remaining Compliance
Only after you have exhausted your ESD opportunities
Conventional practices can be used to obtain any remaining Rev, Cpv, WQv or TP removal for site compliance
Simplified List: Ponds, Wetlands, Filters These practices are independently sized
and designed .
Structural Practices
Contributing
Impervious
Cover (ac)
Direct ESDv
Received by
Practice (cf)
ESDv from
Upstream
Practices (cf)
Treatment
Volume (cf)
Enhanced
Filter
Volume
(cf) Rev (cf)
Phosphor
ous
Removal
Efficiency
Load
Reducti
on
(lbs/yr)
Stormwater Ponds (Level 1) 0 0 0 50% 0.00
Stormwater Ponds (Level 2) 0 0 0 75% 0.00
Stormwater Wetlands (Level 1) 0 0 50% 0.00
Stormwater Wetlands (Level 2) 0 0 75% 0.00
Stormwater Filtering Systems
(Level 1) 0 0 0 60% 0.00
Stormwater Filtering Systems
(Level 2) 0 0 0 65% 0.00
Stormwater Infiltration (Level 1) 0 0 60% 0.00
Stormwater Infiltration (Level 2) 0 0 90% 0.00
Total structural CPv
provided 0
Total Load Reduction (lbs P /
year) 24.12
CPv Requirement Met? NO Total Load Reduction Remaining (lbs P / yr) 0.00
CPv Remaining 62,511
Total Rev provided (cf) 62,485
Rev Requirement Met? YES
Rev Remaining? (cf) 0
Note Level 1 and 2 Design for Critical Area
Step 11Additional Concept Design Work
Site plan showing CIDA and surface area of individual ESD practices
Site testing to confirm feasibility of ESD practices (e.g., water table, slopes, sheet flow distances, infiltration rates, etc).
Analyze system of ESD practices for safe conveyance of the 10 year storm
ESC plan that shows how ESD practices will be protected during construction
.
ESD PRACTICE InstallAfter Con.
Avoid or Protect
Do not use as ESC
Restore Soil
Disconnect/Filter credits X X X X
Permeable Paver X X X X
Rainwater Harvesting X
Gravel Wetlands X X X X
Micro-infiltration X X X X
Rain Garden X X X X
Bioretention X X
Landscape Infiltration X X X X
Grass Swales X X
Bioswales X X
Wet Swales X X
Enhanced Filters X X X X
CONSTRUCTION CONSTRAINTS FORESD MICRO-PRACTICES
Step 12Final design and installation
This is where the rubber meets the road!
.
Session Resources
• R-1 Comparison of Stormwater Regs in the Bay States
• R-2 ESD to MEP Compliance Spreadsheet
• R-3 ESD to MEP Spreadsheet Users Guide
• R-4 Link to Permeable Paver Spec
• R-5 Link to Green Roof Spec
• R-6 Link to Disconnect and Filter Strips Specs
• R-7 Link to UNH Submerged Gravel Wetland Spec
• R-8 Link to Rainwater Harvesting Design Spreadsheet Model
To learn how you can have access to: Discounted Webcasts
Free One-day design workshopsIntensive master stormwater design seminars
Direct On-site technical assistance Self guided web-based learning modules
Visit: www.cwp.org/CBSTP
Upcoming Webcasts – for 2010
• June 13 Stormwater Design for Redevelopment Projects
in MD (Register thru MAWP)
• August 18 Permeable Pavement Design, Installation, and
Maintenance *
• October 20 Rooftop Disconnection, Filter Strips &
Rainwater Harvesting *
* Register at http://www.cwp.org/Webcasts
Thanks
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