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Options for Estimating BMP Performance

(Load Reductions)

Presentation Overview

Informed implementation

Quantifying load reduction associated with management strategies

BMP evaluation Sources of BMP effectiveness information Determining which BMPs are appropriate

Tools that can be used to support the process

Informed Implementation Determine load reduction necessary to meet objectives Identify opportunities for implementation Review design standards/ordinances that will dictate

techniques Identify and narrow down BMP options based on

objectives Identify scale for comparative analysis of

alternatives/scenarios Quantify BMP options

spreadsheet-based watershed/site-scale model

Evaluate scenarios and select management strategy

Be Sure Objectives Have Been Clearly Defined

Example Objectives: Meets NPDES Phase 1 & 2 stormwater

regulations Protect sensitive species Protect water quality by addressing 303(d)

listing concerns Address detention for the control of

stormwater volume and peaks

Quantifying Load Reduction to Meet Objectives

Sources of load quantification data Watershed modeling/load quantification results

(previously described), TMDL reports, etc. Source and spatial targets for implementation

Table 5-4. Nutrient and BOD baseline and allocation loads by contributing subwatershed for impaired waters of the Cedar Creek watershed (daily averages based on the 2001-2003 meteorological regime).

BOD TN TP Reach ID/Subwatershed Baseline

(lb/day) TMDL

(lb/day) Percent

Reduction Baseline (lb/day)

TMDL (lb/day)

Percent Reduction

Baseline (lb/day)

TMDL (lb/day)

Percent Reduction

1, Lower Cedar Creek 24.74 14.12 43% 31.49 17.51 44% 1.54 0.85 44%

2, Slaughter Creek 4.44 2.74 38% 4.74 2.74 42% 0.20 0.12 41%

3, Slaughter Creek 15.16 9.03 40% 23.76 13.31 44% 0.87 0.49 43%

4, Slaughter Creek 61.40 35.49 42% 97.83 54.47 44% 3.65 2.05 44%

5, Slaughter Creek 17.54 9.98 43% 30.81 17.09 45% 1.12 0.62 44%

6, Slaughter Creek 34.70 23.42 33% 34.38 20.68 40% 1.28 0.76 40%

7, Slaughter Creek 31.19 18.67 40% 47.92 26.91 44% 1.87 1.04 44%

8, Slaughter Creek 52.48 32.26 39% 77.65 43.68 44% 2.99 1.69 43%

Identify Opportunities for Implementation

Impervious analysis

Political constraints and priorities

Physical constraints

Environmental constraints

Review Design Standards/Ordinances, if applicable

Zoning ordinances Subdivision ordinances Sedimentation and erosion ordinances Stormwater/water quality management

ordinances

Examples Minimize the total volume of surface water runoff that flows from any specific site during and following development, in order to replicate pre-development hydrology to the maximum extent practicable

Achieve average annual 85% Total Suspended Solids (TSS) removal for the developed area of a site. Areas designated as open space that are not developed do not require stormwater treatment. All sites must employ Low Impact Development (LID) practices to control and treat runoff from the first inch of rainfall.

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BMP influence on hydrograph

Identify BMP Options

Where can I Access Information on BMPs? National Menu of Stormwater Best Management Practices:

http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm International Stormwater Best Management Practices (BMP)

Database: http://www.bmpdatabase.org/

Feedlots DPRA Inc.1986. An evaluation of the cost effectiveness of agricultural best

management practices and publicly owned treatment works in controlling phosphorus pollution in the Great Lakes basin. Prepared for U.S. Environmental Protection Agency, Washington, DC.

Edwards, W.M., L.B. Owens, and R.K. White. 1983. Managing runoff from a small, paved beef feedlot. Journal of Environmental Quality 12(2).

Edwards, W.M., L.B. Owens, R.K. White, and N.R. Fausey. 1986. Managing feedlot runoff with a settling basin plus tiled infiltration bed. Transactions of the ASAE 29(1):243-247.

Forest Seyedbagheri, K. A. 1996. Idaho forestry best management practices: Compilation

of research on their effectiveness. General Technical Report INT-GTR-339. USDA Forest Service, Intermountain Research Station, Ogden, Utah.

Cropland U.S. Environmental Protection Agency (EPA). 1993. Guidance specifying

management measures for sources of nonpoint pollution in coastal waters. EPA-840-B-92-002. Office of Water, Washington, DC.

Urban Athayde, D.N., P.E. Shelly, E.D. Driscoll, D. Gaboury, and G. Boyd. 1983. Results

of the nationwide urban runoff program - volume I - final report. U.S. Environmental Protection Agency, Washington, DC.

Leeds, R., L.C. Brown, M.R. Sulc, and L.VanLieshout. 1994. Vegetative filter strips: Application, installation and maintenance. AEX-467-94. Ohio State University Extension, Columbus, Ohio. http://ohioline.osu.edu/aex-fact/0467.html

MDEQ (Michigan Department of Environmental Quality). 1999. Pollutants controlled: Calculation and documentation for section 319 watersheds training manual. Michigan Department of Environmental Quality, Lansing, Michigan, USA.

Northeastern Illinois Planning Commission (NIPC). 1994. Model best management practice selection methodology & Lake County decision-making framework. NIPC, Chicago, Illinois.

Schueler, T.R. 1987. Controlling urban runoff: A practical manual for planning and designing urban BMPs. Document No. 87703. Metropolitan Washington Council of Governments, Washington, DC.

Davis, A.P., Shokouhian, M., Sharma, H. and C. Minami. 2001. Laboratory study of biological retention for urban stormwater management. Water Environment Research 73:5-14

Maryland Prince George's County and the U.S. Environmental Protection Agency. 1999. Low-Impact Development Design Strategies: An Integrated Design Approach. http://www.epa.gov/owow/nps/lid/lidnatl.pdf

Where can I Access Information on BMPs?

Identify Specific BMP Options

Narrow Down BMPs Based on Objectives

Quantify BMP Options at a Subwatershed or Watershed Scale

Goals Quantify selected BMP strategies (i.e., individual

BMPs or BMP pairings) Watershed scale Local scale

Compare potential load reductions to target Determine optimal strategy considering

environmental benefits and $$

Available Tools Spreadsheet tools Watershed/site-scale models

What Tool Should I Select? Has a model already been used for load

quantification? What scale is important? Is an annual load reduction estimate sufficient? Should individual storms be evaluated?

Spreadsheet tools Normally good for annual/overall reductions Usually at a watershed scale – sometimes at the site

scale Watershed models

Allow for continuous/long-term simulation Often can be used for storm evaluation Ability to function at all scales – site and watershed

Example Spreadsheet Tool for Evaluation of Agricultural BMPs

Field study of BMP performance determines 75% reduction of pollutant load for a 120 acre site

Watershed loading model determined annual loading rates for multiple sites

Spreadsheet can be used to determine BMP load reductions at all sites

Using Watershed Models to Evaluate BMP Performance

Some watershed models are capable of directly evaluating management strategies Agricultural practices: SWAT, AGNPS, GWLF Urban practices: P8-UCM, SWMM Mixed land use: HSPF

Techniques vary by model Assumed BMP removal efficiencies Simulation of storage and pollutant routing

Pollutant losses (e.g., decay, settling) Volume losses (e.g., infiltration, evaporation)

Example Watershed Model BMP Simulation - GWLF

Often used to estimate existing loads

Different BMPs represented using general model functions

Considerations: Universal Soil Loss

Equation parameters Curve #s Manure/fertilizer

application Septic loads User-specified

removal rates

Example Watershed Model BMP Simulation - SWMM

Often used to estimate existing loads

Different BMP scenarios modeled to determine load reductions

Considerations Street sweeping Flow detention and

pollutant removal Varying hydrologic

and pollutant loading assumptions

Summary of Management Practice Simulation Techniques in Selected Models

Additional Models for Detailed BMP Simulation

Detailed site-scale analysis

Specialize in particular types of BMPs

Example: Prince

George’s County (MD) BMP-DSS

Clinton River Watershed Site Evaluation Tool

BMP Optimization

What is optimum? Minimize cost Maximize pollutant flow and/or load reduction Combination of the above

How does one measure optimum? Minimum cost, long-term flows, and/or

pollutant load Best-fit multi-storm curve with pre-developed

condition

Find optimum BMP placement and selection strategies based on pre-selected potential sites and applicable BMP types

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$0 $200,000 $400,000 $600,000 $800,000 $1,000,000 $1,200,000

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Optimal Solution

Initial Run

Identify Optimal SolutionExample of BMP-DSS Multiple Run Output

Clinton River Watershed Site Evaluation Tool

Evaluate potential benefits of BMPs at the site development scale

Inputs Site characteristics BMP

characteristics Outputs

Peak discharge Annual runoff Pollutant Loads

Nitrogen Rate

Target

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2.00

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18.00

1-yr 24-hr storm

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P ost, no BM P s

Existing

P ost, with BM P s

Why Site Evaluation Tool?

Evaluate flow and water quality impact of proposed residential and commercial development

Identify most cost-effective suite of BMPs Support decision-making activities

Tool used in combination with other data/information to make final management decisions at the site scale

Promote consistency Help with Phase 2 reporting requirements

Who Will Use the Site Evaluation Tool?

Local planning review agencies Help with the evaluation of proposed

projects

Potentially could ask developers to use the tool, too

Example Example

Areal Loading RatesExistingLanduse

Designwithout BMPs

Designwith BMPs Target

Meets Goal?

Total Nitrogen (lb/ac/yr) 0.66 9.56 7.17 6.00 NO!Total Phosphorus (lb/ac/yr) 0.11 1.53 0.92 1.33 YesSediment (ton/ac/yr) 0.011 0.120 0.018

Site is located in Urban Residential Nutrient ZoneTN loading rate is higher than the buy-down range of 3.6 to 6 lb/ac/yr

Nitrogen Rate

Target

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2.00

4.00

6.00

8.00

10.00

12.00

Phosphorus Rate

Target

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0.50

1.00

1.50

2.00

Sediment Rate

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

Areal Loading RatesExistingLanduse

Designwithout BMPs

Designwith BMPs Target

Meets Goal?

Total Nitrogen (lb/ac/yr) 0.66 9.56 3.26 6.00 YesTotal Phosphorus (lb/ac/yr) 0.11 1.53 0.30 1.33 YesSediment (ton/ac/yr) 0.011 0.120 0.001

Site is located in Urban Residential Nutrient ZoneTN loading rate is below the buy-down range of 3.6 to 6 lb/ac/yr

Nitrogen Rate

Target

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2.00

4.00

6.00

8.00

10.00

12.00

Phosphorus Rate

Target

0.00

0.50

1.00

1.50

2.00

Sediment Rate

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

Conclusions Quantifying potential impacts from BMPs is

critical to watershed planning Provides a guide toward achieving load reduction goal Informs selection of a management strategy

Spreadsheet and modeling tools are available Spreadsheet tools

Most useful for watershed-scale analysis Operate on a large time step

Watershed/site-scale models Useful for local scale, as well as watershed-scale Can operate on a short time-step (including individual

storms) Provide a key first step for engineering design

Again, one size doesn’t fit all!