Decision-Support Tools and Databases to Inform Regional Stormwater Utility Development in New England

Decision-Support Tools and Databases to

Inform Regional Stormwater Utility

Development in New England

Detenbeck, N.E.1_{, A. Morrison}2_{, J. Morgan}2_{, V. Zoltay}3_{, R. Abele}4_{, J. LeClair}4_{, and T. Garrigan}4

1 _{U.S. Environmental Protection Agency, Atlantic Ecology Division, Narragansett,RI} 2 _{ORISE interns at US EPA Atlantic Ecology Division}

3 _{Abt Associates, Inc., Cambridge, MA} 4 _{US EPA Region 1, Boston, MA}

March 25, 2015

…Our Decision Support Tools &

Databases…

• Assess

stormwater contributions:

 Cost-effective methods for assessing impervious

cover at the parcel scale

• Track

progress:

 New England database of green infrastructure

stormwater BMPs

• Analyze

Costs and Benefits

:



EPA’s Watershed Management Optimization

Support Tool (WMOST)

 Putting co-benefit estimates to good use: potential

partnerships

Assessing stormwater runoff

contributions

Types of Utility Fee Structures Currently in Use

( Western Kentucky University Stormwater Utility Survey 2014 )

Equivalent Residential Unit* Fixed Rate

Tier System

Residential Equivalence Factor (some use Intensity Development Factor based on % impervious area)

Two Level System (Residential/Commercial) Fee Per Parcel Area

Water Meter Unique Fee

By Water Usage

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*

An Equivalent Residential Unit (ERU) is usually the average impervious area on a single family residential parcel, although some communities define it as the average of all residential parcels. Fees for non-residential properties are proportional to the ratio of the parcel impervious area to the ERU.

Data sources for impervious area

in New England

Data source Resolution Year(s) NLCD 30 m 2006, 2011 CT 1m (select watersheds) 2010 MA 1m (statewide) 2005 ME 5m (statewide) 1m (select towns) 2004 2010 NH 30m (Coastal and York County)

1m (organized towns) 1m (select towns) 1990, 2000, 2005, 2010 2003-2007 change 2010 RI 1m (statewide) 2003/2004, 2011 VT 1m (Lake Champlain Basin) 2008, 2011

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NLCD vs. Classified 1m NAIP

1m NAIP imagery

Classified 1m NAIP data 30m NLCD data

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Simplified Impervious

Cover Analysis

• Developed a cost-effective

protocol using readily available

4-band NAIP* data

• Supervised classifications in

GeniePro

– Uses genetic algorithms to

incorporate texture, shape, and

proximity into traditional spectral

inputs

– Provide training pixels using

paintbrush tool, can edit large

areas quickly and easily

* National Agricultural Imagery Program

Simplified Impervious

Cover Analysis

• Pre-processing in ArcGIS

– Add in NDVI and LiDAR

Intensity Bands (where

available)

• Post-processing in ArcGIS

– Add in ancillary E911 Road

data

• Site scale can be classified

in minutes

• $700 for license vs. $$$ for

other more complicated

programs

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Before Road Data

After Road Data

New Impervious Cover

estimates in VT and RI

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¯

(not to scale) Assess

• Stormwater rebates

• Compliance with MS4 permits

• Best Management Practice (BMP) inventory

for maintenance

• Watershed planning and adaptive

management

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Why track treated impervious cover?

Incentives for Low Iimpact

Developement Installation

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• MassDEP gives credits that allow

reduction or elimination of

traditional BMPs used to treat and

infiltrate stormwater.

• Credits given for:

– directing runoff from roads and

driveways to vegetated open areas – directing rooftop runoff to

landscaped or undisturbed areas, – preserving open space with a

conservation restriction

* Information collected by each organization varied widely in attributes,

details and scale

Data sources for Green Infrastructure

BMPs in New England

Source Type of data provided Locational Data

319 Grants Description of project Maps, description of location

ARRA Description of project Maps, description of location

BWSC Type of installation (oil separator, dry well, or grit chamber

Street address Town of Coventry, CT None Street address Connecticut DEEP Site Name, Type of

Installation,

None

Green Roof Database Area of green roof Street address International BMP Database Type of Installation Latitude/longitude of

installation MA UIC Facility Name Street Address MA MS4 Description of project Maps, description of

location ME UIC Description of project Street address ME MS4 Description of project Maps, description of

location NEMO Type of Installation Street Address NH UIC Facility Name Latitude/longitude of

installation and Street Address

New Hampshire Alteration of Natural Terrain Permits

Area disturbed, Impervious Area, Undisturbed Area, Length of roadway, Name of Receiving Water, Type of treatment

Polygon Shapefile

RI UIC Facility Name Street Address RI MS4 Description of project Maps, description of

location UNH Stormwater Database Type of Installation Street Address Vermont Water Quality

Database

Impervious Area, Impervious Area Treated, Name of Receiving Water, Type of treatment Latitude/longitude of installation • Procedure: • Query sources • Map BMPs • Determine IA treated* • Aggregate IA treated across catchments and watersheds Track

Aggregate BMPs*

% Treated IC by

watershed

% Impervious Cover (IC) by watershed

*Data will be made available on EPA’s EDM application (www.epa.gov/edm)

Easy strategies for updating a

stormwater BMP inventory

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California Storm Water Multiple Application and Report Tracking System – SMARTS Part of online application for Construction Permit Notice of Intent

https://smarts.waterboards.ca.gov/smarts/faces/SwSmartsLogin.jsp

WMOST: Cost-benefit analysis tool for

integrated water resource management

WMOST facilitates integrated watershed management

at the municipality scale by asking,

“What is the optimal set of actions to achieve water

quantity related management goals at least cost?”

– Municipalities can Select Goals:

• Meet demand for water or wastewater services

• Achieve minimum and/or maximum in-stream flows to

reduce flooding risks/costs

• Protect fish communities…

– WMOST Functions Support Management Decisions:

• Screen management actions/practices for water and

water-related resources within a watershed context for an

optimal mix

• Provide insight on costs, benefits and trade-offs

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Cost-Benefit

WMOST Optimization Tool

Optimization Capabilities Output Support

Desired

Characteristics

Elements

Generic

Familiar, Accessible Software Natural hydrologic cycle

Human hydrologic system Interaction points and processes

Management practices

Decision support system

Comprehensive & Integrated Framework

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Cost-Benefit

• Stormwater with up to 15 practices evaluated

• Land conservation

• Demand management via pricing and direct measures such as

rebates and incentives

• Change use of existing infrastructure

• Increase capacity of existing infrastructure

• Repair infrastructure

• Build new infrastructure

• Interbasin transfer of water or wastewater

Infrastructure = gw and sw pumping, water treatment, wastewater treatment, water reuse, aquifer storage and recharge

WMOST Management Practices

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Cost-Benefit

Adapted from Limbrunner et al., 2005 Recharge Recharge Recharge Runoff Recharge Runoff Runoff

Runoff and recharge rates:

•

Baseline

•

Detention pond

•

Swale

Generalization of land-use and BMP effects

using Hydrologic Response Units*

HRU 1

*HRU = Combination of land-use and soil type 17

Cost-Benefit

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Sources for WMOST runoff

and infiltration time series

Pawtuxet SWAT w CC NE Coastal SWAT w CC

CT HSPF

Upper Merrimac HSPF Lake Champlain Basin SWAT

Cost-Benefit

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HRU = Hydrologic Response Unit, unique combination of soil type and land-use

Number of management scenarios including baseline

WMOST Main Screen

Specifying Stormwater Practices

• Add a “managed land use set” for each practice

• Practice = structural BMP, multiple structural BMPs, LID (e.g.,

lower IS), LID + BMP

Feasible land area

Costs • Initial = all inclusive

implementation cost • O&M = annual upkeep

through lifetime BMP description

BMP is not permitted on undeveloped land uses

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Cost-Benefit

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WMOSTv2

HSPF model

output d’base

50-year

climate record

FEMA HAZUS

model SOPs

Flooding cost curve

SUSTAIN SWMM

User input:

Mgt options Climate scenario (avg,dry,wet) BMP scenarios Runoff w/out BMPs Runoff w BMPs - Flow -Optimal mgt actions -Avg or current -Wet -Dry - Cost Runoff Infiltration series by HRU

Climate variability module

Flooding module BMP module $0 $15,000 $30,000 $45,000 $60,000 $75,000 $90,000 -100 100 300 500 Dam a g e Cost ( th o u sa n d s o f d o ll a rs)

Recurrence Interval (years)

Potential Building Damage-Cost

Integration of WMOST with other models

Flood Depth and

Damage Assessment

• Determine flood

elevations along

stream reaches

– User-defined options

• FEMA Flood Information Study (FIS) profiles and flood elevations • Elevation data

– Input into ArcGIS

• Subtract surface

elevations from flood elevations

– Compute flood depth

grid

Cost-Benefit

Flood Depth and

Damage Assessment

• Obtain building data

– Building footprints – Parcel data

– Zoning data

• Input flood depth grid and

building data into

HAZUS-MH

Cost-Benefit

Flood Depth and

Damage Assessment

• HAZUS output

– Thematic maps by census block – Infrastructure losses

– Site-specific building losses

Cost-Benefit

Flooding within Plymouth County, MA

Potential

Building Damage

10 Year

Flood

50 Year

Flood

100 Year

Flood

500 Year

Flood

10-Year Flood Depth Grid

500-Year Flood Depth Grid 100-Year Flood Depth Grid

50-Year Flood Depth Grid

Building Count Commercial ₈₃ Industrial ₂₇ Residential ₆₅₇ Total Buildings 767 Building Count Commercial ₂₄₀ Industrial ₆₀ Residential ₁₄₇₆ Total Buildings 1776 Building Count Commercial ₁₃₅ Industrial ₃₉ Residential ₉₃₇ Total Buildings 1111 Building Count Commercial ₁₅₉ Industrial ₄₈ Residential ₁₁₆₁ Total Buildings 1368 Cost-Benefit

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( Western Kentucky University

Stormwater Utility Survey 2014 )

$0 $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 0 100 200 300 400 500 Damage Cost for Residential

Structures (Plymouth County) *thousands of dollars

Average Cost per Residential

Unit= $48,415

Putting costs

into

context

Cost-Benefit

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Quantifying benefits of green infrastructure

BMPs provides information to support

public-private partnerships

Cost-Benefit

Demonstrations can be arranged

GeniePro Impervious Cover Analysis

EDM application data downloads

Watershed Optimization Support Tool +

HAZUS

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