Opti-Tool: A BMP Optimization Tool for Stormwater Management in

EPA Region 1

Mark Voorhees, EPA Region 1

Khalid Alvi, Tetra Tech April 20, 2016

Project Background

• Massachusetts (MA) MS4 General Permit• Phosphorus reduction requirement to meet the Waste Load Allocations for

the impaired watershed

• Phosphorus Control Plan (PCP) • To measure compliance with its phosphorus reduction requirement under

the permit• 3 implementation phases• Reporting on beginning 6 year after the permit effective date • Complete in 20 years

• Opti-Tool• A tool to facilitate storm water engineers to developing Nutrient

Management Plans such as PCP.

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Project Background – cont.

• Proven benefits of optimization techniques in stormwatermanagement • Charles River watershed study

• Practical needs by stormwaterpractitioners• BMP simulation

• BMP optimization

• Independent of ArcGIS

• Simple to use

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Opti-Tool• A spreadsheet-based

BMP optimization tool• Planning Level Analysis

(EPA Region 1 BMP Performance Curves)

• Implementation Level Analysis (EPA SUSTAIN BMP Simulation and Optimization Engine)

• Customized for EPA Region 1

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SUSTAINBMP Simulation

& Optimization

Interface for

data input

Internal data

validation

All inputs

validated?

Post-processing

component

YesNo

Microsoft Excel Environment

Interpreted

optimization results

EXCEL

SOLVER

Interface for

data input

Internal data

validation

All inputs

validated?

BMP

Performance

Curves

YesNo

Interpreted

optimization results

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Opti-Tool: Region Specific Data

• Precipitation conditions • Long-term hourly data at Logan airport (1992 – 2014)

• Land representation• Stormwater monitoring data to calibrate the buildup & washoff processes on

impervious cover

• Long-term landuse specific annual average load export rates

• BMP representation• University of New Hampshire Stormwater Center (UNHSC) BMP monitoring

data to calibrate flow and pollutant loss mechanism in BMPs

• Representative BMP cost information with scaling function

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Opti-Tool: Buildup & Washoff Calibration

• Data used • National Stormwater Quality Database (NSQD)

• Massachusetts and New Hampshire sites

• 100% impervious drainage areas

• Storm events smaller than 1 inch

• Pollutants (TN and TP)

• Buildup & Washoff parameterization• Develop computer codes using GA algorithms to identify the parameter

pattern that best fit the observed data

• Perform sensitivity analysis to identify the robust set of parameters

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Buildup/Washoff: Calibration Plots for TN

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Opti-Tool: Land Use Timeseries Development

• Develop pollutant runoff timeseries• Calibrated SWMM model with selected set of buildup & washoff

parameters

• Regional representative landuse-based pollutant annual average load export rates (kg/ha/yr)

• Buildup parameters adjusted to match the simulated long-term annual average load rate (kg/ha/yr)

• Hourly timeseries (1992 to 2014)

• Compare the simulated EMC distribution against the observed EMC distribution for impervious land use types

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Opti-Tool: BMP Calibration

• Data used • BMP design specifications (from the UNHSC)

• BMP monitoring data (from the UNHSC)

• BMP parameterization• Develop SUSTAIN models

• Represent BMP pollutant loss mechanism (1st order decay and underdrain removal rate)

• BMP hydrologic and water quality performances were calibrated against the observed data

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Hydrology Calibration: Bioretention

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Opti-Tool: BMP Performance Curve

• Data used • Calibrated SUSTAIN model

• Calibrated hourly land use timeseries (1992 to 2014)

• BMP simulation• Run model scenarios for various BMP storage capacity and estimated the

pollutant load reductions

• Develop BMP performance curve (load reduction vs storage capacity)

• Long-term cumulative nutrient load and runoff volume reduction performances for several categories of structural SW controls

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Opti-Tool: BMP Types• Bioretention• Bioretention with internal storage reservoir• Dry Pond• Grass Swale• Gravel Wetland• Infiltration Basin• Infiltration Chambers• Infiltration Trench• Porous Pavement• Sand Filter• Wet Pond

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Opti-Tool: BMP Cost Function

• Combination of the Charles River Watershed Association and UNHSC costs estimates

• Modified capital cost assessment (includes a fixed percentage for Design and Contingency Costs)

• Maintenance hours (from the UNHSC)

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Select Pollutant Type -> TP $3,739,640

Enter Target Load Reduction (%) -> 20.00% 20.00%

Select an option ->BMP Storage

Capacity3,069,121

Enter Land Use Area -> 720.00

Enter Drainage Area -> 250.00

BMP TypeDesign Storage

Capacity (ft3)BMP Cost ($)

Treated

Impervious Area

(ac)

O&M (hr)Load Reduction

(lbs)

Biofiltration with ISR - -$ - - -

Bioretention 72,567 1,061,648$ 50.00 48.64 69.77

Dry Pond - -$ - - -

Grass Swale - -$ - - -

Gravel Wetland 79,639 661,802$ 50.00 39.42 56.00

Infiltration Basin 108,901 643,603$ 50.00 78.03 85.37

Infiltration Chambers - -$ - - -

Infiltration Trench 76,561 904,950$ 50.00 63.83 86.29

Porous Pavement - -$ - - -

Sand Filter - -$ - - -

Wet Pond 72,615 467,638$ 50.00 33.97 48.65

* Note:Only fill in the yellow highlighted cells.

1. Management ObjectiveTotal BMP Cost ($)

Total Pollutant Load Reduction (%)

2. Optimization Target

5. Optimal Solution

Total BMP Storage Capacity (gal)

3. Watershed InformationTotal Impervious Area (ac)

4. BMP InformationTotal Treated Impervious Area (ac)

Planning Level AnalysisThe purpose of this tool is to provide decision-makers a comprehensive overview of stormwater management opportunities in a given watershed. The tool will characterize the watershed characteristics and opportunities for applying a variety of BMP technologies to various source areas based on land use, soils, and impervious cover. There are two approaches of the planning-level analysis tool:

1: BMP Storage Capacity – to evaluate the changes in hydrologic and water quality benefits as the BMP/LID sizes are increased in fixed increments; and2: BMP Drainage Area – to determine how much impervious area would require treatment if specified BMP design capacities are selected for each HRU type to be treated.

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Run Single Scenario

Run Optimize Scenario

Subwatershed

Conduit/stream channel

BMPs

Optimization setup

File operation

Input parameters

with default values

SUSTAIN

input file

SUSTAIN

Optimizer

Post-processing

+

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Opti-Tool: Implementation Level Analysis

Opti-Tool: Bartlett Brook

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• Drains to Lake Champlain, VT

• Impaired waterway on the 2006 Vermont 303(d)

• Sub-watershed land use distribution similar to Bartlett Brook watershed

• Opti-Tool demonstration focus

• Develop cost-effectiveness curve for TP annual average load reduction

Opti-Tool: Model Inputs

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• Subwatershed delineation

• HRU representation• Landuse, soil, slope combination

• Runoff timeseries (flow, pollutant load)

• BMP type and design specification

• BMP cost function

• BMP treatment area delineation

• BMP/Subwatershed routing network

Opti-Tool: Model Setup

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0% 10% 20% 30% 40% 50% 60% 70%

Co

st (

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ion

$)

% Reduction (Annual Average Load)

All Solutions Selected Best Solution

Opti-Tool: Model Results

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Target Reduction

(%)

Solution Total

Cost (Million $)

Solution Reduction

(%)

30.0% 3.24E+00 30.03%

BMP ID BMP Type BMP Area (ft^2)BMP Storage Depth

(ft)

Treated Impervious Area

(ac)

Annual Maintenance

(hours)Cost ($)

BMP1 DRYPOND 5000 10.4 1.23 29.52 353,600

BMP2 DRYPOND 16400 10.4 4 96.00 1,159,808

BMP3 DRYPOND 56 8.4 0.36 8.64 3,199

BMP4 DRYPOND 39100 6.4 10.98 263.52 1,701,632

BMP5 DRYPOND 500 5.85 2.52 60.48 19,890

Summary• Opti-Tool for a wide range of users

• Municipal officials• State and EPA staff (stormwater and nonpoint source programs)• Consultants

• Software requirement• Microsoft Excel

• Customized for EPA Region 1 • Regionally calibrated land use based pollutant runoff timeseries• Regionally calibrated BMP performance curves• Regionally representative BMP cost function

• Results are consistent with loading rates and BMP performance documented in the upcoming EPA Region 1 MS4 permits

• The tool can be readily adapted to represent site specific loading and climate conditions throughout the region

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