Opti-Tool for Stormwater and Nutrient Management - NEIWPCC

Opti-Tool for Stormwater and Nutrient ManagementMark Voorhees, US Environmental Protection Agency, Region 1 ([email protected])

What is Opti-Tool?Opti-Tool (Stormwater Management Optimization Tool) is a spreadsheet-based optimization tool that provides both a planning level and implementation level analysis. The tool helps planners determine the best mix of BMPs to provide the greatest benefit for achieving water resources goals while balancing costs.

The Planning Level Analysis provides maximum possible load reduction for all feasible BMP opportunities or cost-effective single solution that meets the numeric load reduction target. The Implementation Level Analysis provides optimal combination of different BMP types, sizes and spatial locations or cost-effective solutions for a range of load reduction targets.

Benefits of Opti-Tool Accessible to all users with Microsoft Excel 2013 software;

Represents actual regional precipitation conditions;

Incorporates best available information on stormwater urban

runoff nutrient quality;

Incorporates best available information for estimating long-term

cumulative nutrient load and runoff volume reduction

performances for 11 categories of structural stormwater controls;

Incorporates representative stormwater control units cost

information with scaling function to account for specific site

conditions and development density;

Includes flexibility to conduct either watershed planning level or

detailed site specific design-level analyses; and

Performs optimization analyses to determine most cost-effective

selection of structural stormwater controls for achieving

pollutant loading and runoff flow related reduction targets.

Regional Specific DataMultiple datasets required as input for Opti-tool were customized for EPA Region 1.

1.Regionally calibrated BMP performance curves were developed based on University of New Hampshire Stormwater Center (UNHSC) BMP monitoring data. The BMP data was utilized to calibrate BMPs.

2.Charlies River Watershed Association and the UNHSC provided BMP cost estimates.

3.Compared weather stations from major urban areas across the New England states to determine Boston Logan Airport station is a representative precipitation data set for Region.

4.Long-term pollutant runoff time series for typical land uses in the region were updated. Storm water monitoring data was used to calibrate the buildup and washoff processes on impervious cover.

Landuse TypeImpervious/

PerviousAgriculture ImperviousForest ImperviousHighway ImperviousIndustrial ImperviousCommercial ImperviousHigh Density Residential ImperviousMedium Density Residential ImperviousLow Density Residential ImperviousOpen Land ImperviousAgriculture PerviousForest PerviousDeveloped A PerviousDeveloped B PerviousDeveloped C PerviousDeveloped C/D PerviousDeveloped D Pervious

Planning Level AnalysisThe required information is separated into four different sections: management objective, optimization target, watershed information, and BMP information.

The Run Single Scenario analysis can estimate the BMP Storage Capacity for any given runoff treatment depth from the BMP impervious drainage areas. The RunOptimize button will begin the performance optimization process. The optimization analyses are performed through Excel Solver.

The different scenario approaches calculates the BMP storage capacity (ft3), BMP cost ($), treated impervious area (ac), annual operation and maintenance hours (hr), and pollutant load reduction (lbs) for the BMP defined with drainage area, from the BMP information step.

Implementation Level AnalysisThe Implementation Level Analysis allows users to enter watershed and BMP design information through a series of customized forms and tables. The steps are tabled in order on the Implementation Level analysis interface.

Target Reduction (%)

Solution Total

Cost (Million $)

Solution Reduction

(%)

52.1% 84.53 52.10%

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

(ft)

Treated Impervious Area

(ac)Annual Maintenance (hours) Cost ($)

BMP1 INFILTRATIONBASIN 690000 2.0005 653.85 NOT ASSESSED 17,226,706



BMP4 BIORETENTION 432 1.768 0.22 4.55 23,616

BMP5 BIORETENTION 52360 1.768 33.12 685.58 2,862,341



BMP8 ENHANCEDBIORETENTION 100800 2.28 89.08 NOT ASSESSED 7,175,105

BMP9 SUBSURFACEGRAVELWETLAND 85200 3.2 107.58 2334.49 4,787,558

The user is responsible for defining the number of subbasins, junctions, land uses, BMPs, and pollutants under Watershed Information step. Then, throughout the step by step process, the user defines characteristics of each component.

The View Results option allows users to provide a target value, and Opti-Tool searches for the nearest solution and provides the solution reduction percentage and the total cost. It also provides the BMP information for the BMPs defined in the project. The BMP information includes: BMP Type, BMP Area (ft2), BMP Storage Depth (ft), Treated Impervious Area (ac), Annual Maintenance (hours), and BMP Cost($).

The Cost-Effectiveness curve references the output files and provides the user an opportunity to have a meaningful interaction with the simulation results. Implementation level analysis yields a graph of all solutions and identification of the “best” solutions in a cost vs. % reduction graph.

Cost saving of $47.5 million (56%) by lowering 10% of the numeric target (42.1%).

S T O R M W A T E R is a leading cause of poor water quality. Rain or melted snow runs down driveways, sidewalks and streets carrying oil, dirt and other pollutants into nearby waterways. Polluted runoff, which can cause erosion and flooding, runs into waterways and degrades plants, f ish, shellf ish and other wildlife. In water used for recreation, the runoff can lead to illness, and people who eat contaminated fish can also become sick. Untreated stormwater can also contaminate drinking

water sources.

U . S . E P A | S T O R M W A T E R O U T R E A C H I N M A S S A C H U S E T T S

t printed on 100% recycled paper, with a minimum of 50% post-consumer waste, using vegetable-based inks

March 2016

cont inued >

This summer, EPA Region 1 will complete work on Opti-Tool. Opti-Tool is a spreadsheet-based stormwater best management practices optimization tool. Opti-Tool is designed for use by municipal SW managers and their consultants to assist in developing technically sound and optimized cost-effective SW management plans.

Controlling and treating discharges of SW runoff, especially from highly developed urban areas, can be technically difficult and costly. Opti-Tool is designed to help SW managers navigate and overcome the planning and assessment challenges associated with retrofitting SW controls into existing developed landscapes. These SW controls are for the dual purposes of reducing pollutant loads of nutrients (TP, TN), sediments (TSS), and zinc (a surrogate for metals most commonly found in SW runoff), as well as addressing hydrologic imbalances.

Benefits of the tool• Accessible to all users with Microsoft Excel 2013 software.

• Represents actual regional precipitation conditions (long-term hourly data, 1992-2014).

• Incorporates best available information on SW runoff nutrient quality, including build-up/wash off processes, especially important in New England where storms are predominantly small events (e.g., 50% < 0.3 in.; 70% < 0.6 in.; 80% < 0.8 in.; and 90% < 1.2 in.).

• Incorporates best available information for estimating long-term cumulative nutrient load and runoff volume reduction performances for 11 categories of structural SW controls - UNHSC is one of the best sources of data.

• Uses information which is being shared with other regional tool developers to promote the use of consistent and high quality data.

• Incorporates representative SW control units cost information with scaling function to account for site specific conditions and development density.

• Includes flexibility to conduct either watershed planning level or detailed site specific design-level analyses.

• Performs optimization analyses to determine most cost-effective selection of structural SW controls for achieving pollutant loading and runoff flow related reduction targets.

Stormwater Managementwith Opti-Tool

MVOORHEE

Sticky Note

Marked set by MVOORHEE

• Provides results consistent with phosphorus source load rates and SW control reduction values in EPA Region 1’s new small MS4 general permits.

What a User needs to doThe user defines the targeted geographic area, land use distribution by impervious and pervious cover, pollutants of concern (or runoff volume), and follows user-friendly screen prompts for choices on characterizing watershed study area, soil, BMP types and hydraulic network/conduit information.

Results After a given scenario simulation has run successfully, results are provided depending on the user’s selection of a cost-effectiveness curve or a flow duration curve. Planning level scenarios yield “optimal solution” tables of different BMP types/sizes/O&M

costs/and corresponding load reduction. Implementation level analysis yields a graph of all solutions and identification of the “best” solutions in a cost vs. % reduction graph.

Coming Soon: A separate but compatible BMP Tracking and Accounting Tool (BATT) is being designed for use by small MS4 permittees for accounting, tracking and reporting on nutrient load reductions associated with BMP SW controls implemented and to demonstrate compliance with nutrient reduction requirements in EPA Region 1’s new stormwater permits for Massachusetts and New Hampshire.

Microsoft Mention of commercial products, services or organizationsdoes not constitute an endorsement by the U.S. EPA

TetraTech, Inc. Developed by TetraTech, Inc. for the U.S. EPA under contract.

Historical OverviewCharles River P TMDLs,

(Lower 2002–2007

Upper/Middle 2006-2011)

Residual

Designation

Petition,~2007

Sustainable

Funding Study

&

EPA Updated

Optimization

Analysis, 2010-11

Draft

Residual

Designation

Permit, ~2010

SW Control

Performance

Analyses

2007-10

Accounting System

Phosphorus Source

Loads & Credible

SW Control

Reduction Credits

~2010-16

Low Cost SW

Control

Performance

Analyses

~2013

MS4 Permits

with TMDL

Related

Reductions

Requirements

MA Final (2016)

NH Draft

(2013,15)

BMP Performance Curve: Gravel Wetland

Land Use: Commercial

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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Depth of Runoff Treated (inches)

Po

llu

tan

t R

em

oval

TSS TP Zn

Stormwater

Management

Optimization

Analysis, 2010-11

Permitting Tools: Stormwater Management Optimization Tool “Opti-Tool”

(2013-16), and BMP Accounting and Tracking Tool “BATT” (2015-2016)

SW Management in Developed Landscapes: Technical & Economic Feasibility Challenges/Opportunities

CONCEPTS

• Comprehensive watershed planning vs. project by project

• Credible best estimates: • IC source loadings

• SW Control cumulative reductions (all sizes)

• Costs

• Accounting System for planning & compliance

• Every little bit counts

• Optimization analyses

Stormwater Phosphorus & Nitrogen

Phosphorus Highly associated with

very fine particles ~ 40 microns

Fine particles readily washed from impervious surfaces with smallamounts of rainfall

Stormwater controls must have filtration component to be effective

Nitrogen N Oxides are readily

washed off in early portion of rain events

Organic nitrogen can be a significant part of N load

High removals of SW nitrogen may require de-nitrification

Mass loading for DRO, Zn, NO3, TSS as a function of normalized storm volume for two storms: (a) a large 2.3 in rainfall over 1685 minutes; (b) a smaller 0.6 in storm depth over 490 minute. DRO=diesel range organics, Zn= zinc, NO3= nitrate, TSS= total suspended solids

(Source: Dr. James Houle, UNHSC)

4

90% of DIN mass

in first 0.2 in

runoff or 20% of

WQV

VISR/WQV =0.2

100% of DIN mass

in first 0.1 in

runoff or 10% of

WQV

VISR/WQV =0.1

New England Region- Cumulative Precipitation, Runoff Volume, Total Nitrogen Load Delivery from Impervious Cover

5

0%

16.2%

29.1%

55.7%

74.6%

95.0%

0%

28.4%

45.1%

75.9%

97.3% 98.0%

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Cu

mu

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ve P

erc

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)

Runoff Depth from Impervious Cover (IC), inchesRunoff volumes calculated by assuming initial abstraction of 0.1 inch of rainfall depth per event

Estimated Cumulative Percent (%) Runoff Volume and Total Nitrogen Load Delivery from Impervious Cover (IC)

Based on Hourly Precipitation Data - Boston, MA (1992-2014) and Median TN EMC data for Commercial/Industrial from NSQD - Rainfall Regions 1 & 2 (Pi

cumulative % average annual runoff from IC

cumulative % average annual TN Load from IC

Importance of Impervious Area (IA) in SW Pollutant Loading

• Impervious cover (IC) generates much greater runoff volume than pervious areas, therefore in developed landscapes IC is typically the most significant contributor of overall SW pollutant loading and retrofits should focus on IC

Calculated annual phosphorus load export rates (PLER) based on various hydrologic conditions for a range of stormwater total phosphorus (TP) concentrations

Watershed surface

DescriptionAnnual Runoff

Yield, MG/ha/yr

Annual Phosphorus Load Export (PLE), kg/ha/yr

Flow weighted SW TP conc., mg/L ----->

0.10 0.20 0.30 0.40 0.50 1.00

Impervious surface impervious surface 2.59 0.98 1.96 2.94 3.92 4.90 9.79

Pervious area HSG A well drained soils 0.07 0.03 0.05 0.08 0.10 0.13 0.25

Pervious area HSG Bmoderately drained

soils0.21 0.08 0.16 0.24 0.32 0.40 0.79

Pervious area HSG C limited permeability 0.41 0.15 0.31 0.46 0.62 0.77 1.54

Pervious area HSG D poorly drained soils 0.69 0.26 0.52 0.78 1.04 1.30 2.60

Annual Runoff yield by SWMM for hourly rainfall - Boston MA (1998-2002), Flow-weighted SW TP conc. = total annual P load divided by total annual runoff volume.

HSG= Hydrologic Soil Group, MG= million gallons, ha = hectare (1 ha= 2.47 acres)

Typical range of urban

SW TP concentrations

EPA Region 1’s Proposed Phosphorus Load Export Rates for use in Stormwater Permitting Process

Table 1: Average Annual Phosphorus Load Export Rates for use in the MA MS4 Permit

Phosphorus Source Category by Land Use

Land Surface CoverPhosphorus Load

Export Rate, Kg/ha/yr

Comments

Commercial (Com) and Industrial (Ind)

Directly connected impervious 2.0 Derived using a combination of the Lower Charles USGS Loads study and NSWQ

dataset. This PLER is approximately 75% of the HDR PLER and reflects the difference in the distributions of SW TP EMCs between Commercial/Industrial and Residential.

PerviousSee* DevPERV

Multi-Family (MFR) and High-Density Residential (HDR)

Directly connected impervious 2.6 Largely based on loading information from Charles USGS loads, SWMM HRU modeling, and NSWQ data setPervious See* DevPERV

Medium -Density Residential (MDR)Directly connected impervious 2.2 Largely based on loading information from Charles USGS loads, SWMM HRU modeling,

and NSWQ data setPervious See* DevPERV

Low Density Residential (LDR) - "Rural"

Directly connected impervious 1.7 Derived in part from Mattson Issac, HRU modeling, lawn runoff TP quality information from Chesapeake Bay and subsequent modeling to estimate PLER for DCIA (Table 14) to approximate literature reported composite rate 0.3 kg/ha/yr.


Highway (HWY)

Directly connected impervious 1.5 Largely based on USGS highway runoff data, HRU modeling, information from Shaver et al and subsequent modeling to estimate PLER for DCIA for literature reported composite rate 0.9 kg/ha/yr.

Pervious See* DevPERV

Forest (For)

Directly connected impervious 1.7 Derived from Mattson & Issac and subsequent modeling to estimate PLER for DCIA that corresponds with the literature reported composite rate of 0.13 kg/ha/yr (Table 14) Pervious 0.13

Open Land (Open)

Directly connected impervious 1.7 Derived in part from Mattson Issac, HRU modeling, lawn runoff TP quality information from Chesapeake Bay and subsequent modeling to estimate PLER for DCIA (Table 14) to approximate literature reported composite rate 0.3 kg/ha/yr.


Agriculture (Ag)

Directly connected impervious 1.7 Derived from Budd, L.F. and D.W. Meals and subsequent modeling to estimate PLER for DCIA to approximate reported composite PLER of 0.5 kg/ha/yr.Pervious 0.5

*Developed Land Pervious (DevPERV)-Hydrologic Soil Group A

Pervious0.03

Derived from SWMM and P8 - Curve Number continuous simulation HRU modeling with assumed TP concentration of 0.2 mg/L for pervious runoff from developed lands. TP of 0.2 mg/L is based on TB-9 (CSN, 2011), and other PLER literature and assumes unfertilized condition due to the upcoming MA phosphorus fertilizer control legislation.

*Developed Land Pervious (DevPERV)-Hydrologic Soil Group B

Pervious0.13

*Developed Land Pervious (DevPERV) -Hydrologic Soil Group C

Pervious

0.24

*Developed Land Pervious (DevPERV) -Hydrologic Soil Group C/D

Pervious0.33

*Developed Land Pervious (DevPERV) -Hydrologic Soil Group D

Pervious

0.41

Accounted for in Opti-

Tool

SW Control Long-term Cumulative Performance Curve Concept

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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Ru

no

ff V

olu

me

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du

cti

on

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mu

lati

ve

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os

ph

oru

s L

oa

d R

em

ova

l

Physical Storage Design Capacity, Impervious Surface Runoff Depth (inches)

SW Control Performance Curves Surface Infiltration Practices

rain gardens, swales, basins, etc.(Saturated Soil Infiltration Rate 0.52 in/hr)

TP Volume

Small Rain Garden http://www.flickr.com/photos/cdwilliams1/2915660835/

Larger Stormwater Basin http://www.flickr.com/photos/leonizzy/6232922661/


Tool

http://www.flickr.com/photos/cdwilliams1/2915660835/

http://www.flickr.com/photos/leonizzy/6232922661/

Unit Cost information for Various SW Controls

SW Control TypeCost ($/ft3) –2016 dollar

Bioretention $ 14.63

Dry Pond $ 6.44

Enhanced Bioretention $ 14.77

Infiltration Basin $ 5.91

Infiltration Chamber $ 60.4

Infiltration Trench $ 11.82

Porous Pavement (Asphalt) $ 5.03

Porous Pavement (Concrete) $ 17.1

Sand Filter $ 16.97

Subsurface Gravel Wetland $ 8.31

Wet Pond $ 6.44

SW Control Development TypeCost

Adjustment Factor

New BMP in Undeveloped Area 1.00

New BMP in Partially Developed Area 1.50

New BMP in Developed Area 2.00

Difficult Installation in Highly Urban Settings 3.00

9

Unit cost is based on control’s storage capacity (ft3) to hold water (e.g., pond volume

+ void space volume) making it straight forward to integrate cost and performance

information, (e.g., $ per pound of P removed).


Tool

Estimates of hours of level of effort for Operation

& Maintenance (O&M) has been estimated for each

of the SW control types.

Demonstration Project: Optimization Analysis for 3 Upper Charles Towns

• Conducted by Tetra Tech to evaluate broad SW Management Strategies to inform Permit Development

• Big Picture Key Findings:• The range in estimated costs for implementation of SW controls watershed-wide to achieve a

set phosphorus reduction target is HUGE

• Standardize sizing of controls (one size fits all) will be much more expensive (administrative ease may be unaffordable and unwise)

• Comprehensive optimization process will help identify the best combination of controls, design capacities and locations to achieve required load reduction at least cost

Demonstration Project: Optimization Analysis for 3 Upper Charles Towns

Example Results

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0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00%

Annual average TP load reduction

To

tal c

os

t (m

illio

n $

)All scenarios evaluated

52%, 26.08

52%, $98 Million

52%, $26 Million

10/25/2016 12

$193,788,094

$151,722,468

$114,715,944

$104,004,002

$97,826,021$85,902,399

$50,000,000

$100,000,000

$150,000,000

$200,000,000

$250,000,000

60% 70% 80% 90% 100%

Esti

mat

ed

Co

nst

ruct

ion

Co

st, $

incl

ud

es

a 3

5%

fo

r e

ngi

ne

eri

ng

and

co

nti

nge

nci

es

Percentage of Impervious Area Treated in Charles River Watershed of Milford, Bellingham & Franklin, MA

Estimated Construction Costs for Structural Stormwater Controls to Achieve a 40 % Reduction in Phosphorus Load form the Charles River Watershed in

Milford, Bellingham & Franklin based on Amount of Impervious Area Treated

10/25/2016 13

1.40

0.91

0.68

0.470.43 0.39

0.29

0.00

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0.80

1.00

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50% 60% 70% 80% 90% 100%

We

igh

ted

ave

rage

cap

acit

y o

f st

ruct

ura

l co

ntr

ols

–in

che

s o

f ru

no

ff f

rom

imp

erv

iou

s co

ver

Percentage of Impervious Area Treated in CRW of Milford, Bellingham, & Franklin MA

Average Capacity of structural controls needed to achieve a phosphorus load reduction of 40% in the Charles River Watershed of Milford, Bellingham &

Franklin, MA based on the treatment of varying amounts of impervious area

10/25/2016 14

1277

14291516

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1848

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al r

un

off

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e r

ech

arge

d b

y In

filt

rati

on

pra

ctic

es

M

G/y

r

Percentage of impervious area treated in CRW of Milford, Bellingham & Franklin MA

Estimated annual stormwater recharge volume by infiltration practices for varying amounts of impervious area treated associated with achieving a 40% phosphorus

load reduction from the Charles River Watershed within Milford, Bellingham & Franklin, MA

2548 MG/yr -Average annual potable water consumption for Milford, Bellingham and Franklin, MA

Opti-Tool: IntroductionOverview of the planning and implementation options

Khalid AlviEnvironmental EngineerTetra Tech, Incorporated

Fairfax, Virginia

Project Background

• Small MS4 General Permit for MA and NH• 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

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

Management Plans such as PCP.

16

Project Background – cont.

• Proven benefits of optimization techniques in stormwater management • Charles River watershed study

• Practical needs by stormwater practitioners• BMP simulation

• BMP optimization

• Independent of ArcGIS

• Simple to use

17

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

18

Excel Inputs

Planning Level Input:

Target pollutant load reduction

Watershed land use area

BMP drainage area

Optimization method

Implementation Level Input:

Watershed, land use, pollutants

Potential BMPs representation

BMP treated area

Management objective

Output Postprocessor:

Cost-effectiveness solution

Optimal management options• BMP size and cost

• Treated impervious area

Output Postprocessor:

Cost-effectiveness curve

Optimal management options

• BMP type, size, and cost

Excel Outputs

Excel Solver

SUSTAIN Optimization

Engine

InputText File

BMP Performance

Curve

Opti-Tool: Planning and Implementation Options

Opti-Tool: Example Applications

• Planning Level Analysis• Maximum possible load reduction for all feasible BMP opportunities

• Watershed scale and/or site scale

• Aggregated BMP representation (grouping same BMP types as one unit)

• No BMP nesting (parallel BMPs)

• Cost-effective single solution meeting the numeric target

• Implementation Level Analysis• Optimal combination of different BMP types, sizes, and spatial locations

• Watershed scale and/or site scale

• Aggregated and/or distributed BMP representation

• simple to complex BMP routing network (BMPs in parallel and/or in series)

• Cost-effective solutions (CE-curve) for a range of load reduction targets

Opti-Tool: Region Specific Data

• Precipitation Representation• 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

21

Opti-Tool: Precipitation Analysis

• Data Used • 12 weather stations from major urban areas

• Represents climate regions in New England states

• NCDC hourly weather records

• Summary Results• Average annual precipitation varies from 34 in.

to 46 in. with average value of 42.3 in.

• Similar precipitation frequency distribution• 48 percent of the events are < 0.1 inch

• 45 percent of the events are 0.1 to 1.0 inch

• 7 percent are > 1.0 inch

• Boston Logan Airport station is representative22

Opti-Tool: Buildup & Washoff Calibration

• Data Used • National Stormwater Quality Database (NSQD)

• Massachusetts and New Hampshire sites

• 100% impervious drainage areas

• Storm events smaller or equal than 1 inch

• Pollutants (TP and TN)

• Buildup & Washoff Parameterization• Developed computer codes using GA algorithms to identify the parameter

pattern that best fit the observed data

• Calibrated 21 sets of parameters representing different initial conditions

• Performed sensitivity analysis to identify the robust set of parameters

23

Buildup/Washoff: Calibration Plots for TP

24Reference: Technical Memos.pdf

Opti-Tool: HRU Timeseries Development

• Data Used• Selected robust set of pollutant buildup & washoff parameters in

calibrated SWMM model

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

• Hourly precipitation and PET timeseries (1992 to 2014)

• Summary Results• Adjusted buildup parameters to match the simulated long-term

annual average pollutant loading rate (kg/ha/yr)

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

• Developed HRU hourly timeseries for flow, TP, TN, and TSS 25

26Reference: Technical Memos.pdf

Opti-Tool: HRU Types

27

1. Commercial/Industrial

2. High-Density Residential

3. Medium-Density Residential

4. Low Density Residential

5. Highway

6. Open Land

7. Forest

8. Agriculture

9. Forest Pervious10. Agriculture Pervious11. Developed Land Pervious –

Hydrologic Soil Group A12. Developed Land Pervious –

Hydrologic Soil Group B13. Developed Land Pervious –

Hydrologic Soil Group C14. Developed Land Pervious –

Hydrologic Soil Group C/D15. Developed Land Pervious –

Hydrologic Soil Group D

Opti-Tool: BMP Calibration

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

• BMP monitoring data: flow and water quality (from the UNHSC)

• BMP Parameterization• Developed SUSTAIN models

• Calibrated water quality parameters (1st order decay and underdrain removal rate)

• Compared simulated BMP hydrograph and water quality performance against the observed BMP hydrograph and observed BMP efficiency

• Calibrated structural stormwater BMPs for flow, TP, TN, and TSS

28

Bioretention: Hydrology Calibration

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2:2

0

2:4

0

3:0

0

Time

Flo

w (

gp

m)

Observed inflow

Generated inflow to bio-retention area

Observed outflow

Calibrated BMPDSS outflow

29

Opti-Tool: BMP Performance Curve

• Data Used • Calibrated SUSTAIN model• Calibrated hourly HRUs timeseries (1992 to 2014)

• BMP Simulation• Run BMP scenarios for a range of storage capacity and estimated the

pollutant load reductions• Developed BMP performance curve (pollutant load reduction vs storage

capacity)

• Developed long-term cumulative pollutant load and runoff volume reduction performances for several categories of structural stormwater controls

30

31

Opti-Tool: BMP Types

32

1. Bio-filtration

2. Enhanced Bio-filtration with Internal Storage Reservoir3. Dry Pond

4. Grass Swale5. Gravel Wetland6. Infiltration Basin7. Infiltration Chambers8. Infiltration Trench9. Porous Pavement10. Sand Filter11. Wet Pond

Opti-Tool: BMP Cost Function

33

• 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)

Reference: Technical Memos.pdf

BMP Type Cost ($/ft3) – 2016

Bioretention $ 15.46

Dry Pond $ 6.8

Enhanced Bioretention $ 15.61

Infiltration Basin $ 6.24

Infiltration Chamber $ 67.85

Infiltration Trench $ 12.49

Porous Pavement (Porous Asphalt Pavement) $ 5.32

Porous Pavement (Pervious Concrete) $ 18.07

Sand Filter $ 17.94

Subsurface Gravel Wetland $ 8.78

Wet Pond $ 6.8

Opti-Tool: Interfaces

Planning Level: Two Approaches

• BMP Storage Capacity • Evaluate the BMP performance for a design criterion (e.g., capture 1 inch

storm size)• Evaluate the changes in water quality benefits as the BMP sizes are changed • Identify the most cost-effective BMP storage capacity that meets the target

pollutant load reduction

• BMP Drainage Area• Determine how much impervious drainage area would require treatment if

specified BMP design capacities were selected• Identify the extent of impervious area to be treated that can provide the

target pollutant load reduction• In this approach, both the BMP storage capacity and BMP cost are fixed.

Opti-Tool: Planning Level

Opti-Tool: Interfaces

Opti-Tool: Implementation Level

38

Opti-Tool: Model Results

• Cost $84.53 million to meet 52.1% average annual TP load reduction target

• Cost saving of $47.5 million (56%) by lowering 10% of the numeric target (42.1%)

0

20

40

60

80

100

120

140

160

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

Co

st (

Mill

ion

$)

% ReductionAnnual Average Load

All Solutions Best Solutions Target Solution

Target Reduction (%)

Solution Total

Cost (Million $)

Solution Reduction

(%)

52.1% 84.53 52.10%

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

(ft)

Treated Impervious Area

(ac)Annual Maintenance (hours) Cost ($)




BMP4 BIORETENTION 432 1.768 0.22 4.55 23,616




BMP8 ENHANCEDBIORETENTION 100800 2.28 89.08 NOT ASSESSED 7,175,105

BMP9 SUBSURFACEGRAVELWETLAND 85200 3.2 107.58 2334.49 4,787,558

Benefits of Opti-Tool

• Accessible to all users with Microsoft Excel 2013 software

• Represents actual regional precipitation conditions

• Incorporates best available information on stormwater urban runoff nutrient quality

• Incorporates best available information for estimating long-term cumulative nutrient load and runoff volume reduction performances for 11 categories of structural stormwater controls

• Uses Information which is being shared with other regional tool developers to promote the use of consistent and high quality data

Benefits of Opti-Tool – cont.

• Incorporates representative stormwater control units cost information with scaling function to account for specific conditions and development density

• Includes flexibility to conduct either watershed planning level or detailed site specific design-level analyses

• Performs optimization analyses to determine most cost-effective selection of structural stormwater controls for achieving pollutant loading and runoff flow related reduction targets

Flexible to Adapt for Other EPA Regions

• Develop local weather data• Hourly precipitation

• Daily temperature (min and max)

• Run SWMM model (provided in the installation package)• Local weather data input

• SWMM hourly HRU timeseries output

• Run HRU utility tool (provided in the installation package)• SWMM hourly HRU timeseries input

• Opti-Tool hourly HRU timeseries output

• Update default data (provided in the installation package)• HRU timeseries and local BMP cost function (optional)

Feedback and Other Presentations

• Questions or comments?• Mark Voorhees ([email protected])

• Links to other presentations• https://www.epa.gov/npdes/npdes-stormwater-webcasts

Documents

Opti-Tool for Stormwater and Nutrient Management - NEIWPCC