ALERT: AMEC Load Estimation and Reduction Tracking

Esri UC2013 .

2013 Esri International User Conference July 8–12, 2013 | San Diego, California

Restoring the Chesapeake Bay

with ArcGIS

Tools for Planning Stormwater Treatment

Thomas Williams, EIT, LEED AP

AMEC Environment & Infrastructure

Esri UC2013 .

The Chesapeake Bay

• Largest Estuary in the US

• Drains over 64,000 mi2

- 6 States, plus Washington, DC

• 2009 Executive Order:

- Declared the Bay a National

Treasure

- Called for a renewed effort to

restore and protect the Bay

- Paved the way for the

Chesapeake Bay TMDL

Restoring the Chesapeake Bay with ArcGIS

Esri UC2013 .

The Chesapeake Bay TMDL

• What is a TMDL?

- Total Maximum Daily Load

- EPA-established “pollution diet.”

- Maximum amount of pollution a

water body can receive and still

remain healthy.

• The Chesapeake Bay TMDL

focuses on three pollutants:

- Nitrogen

- Phosphorus

- Sediment


Image Credit: 1

Esri UC2013 .

Urban Stormwater in the Bay Watershed


• Urban stormwater pollution is a major aspect

of the Chesapeake Bay TMDL.

• The Bay TMDL is affecting Municipal

Separate Storm Sewer System (MS4)

operators throughout the Bay Watershed.

• There are many existing tools for stormwater

planning, but most are non-spatial.

• How can we use GIS to…

• evaluate stormwater treatment options?

• track TMDL compliance?

• make watershed planning easier?

Image Credit: 2

Esri UC2013 . Restoring the Chesapeake Bay with ArcGIS

ALERT

• AMEC developed a set of Python tools for ArcGIS, called

ALERT

• AMEC Load Estimation and Reduction Tracking

• Initially designed around Virginia’s draft regulations to

implement the Chesapeake Bay TMDL.

• ALERT framework has since been updated and expanded to

apply outside of Virginia and the Chesapeake Bay.

• Built to help communities:

• plan stormwater projects

• quickly evaluate different scenarios

• estimate the cost of compliance

!

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ALERT Process Diagram


Water Quality Plan

Start / Finish

ArcGIS

Silverlight

Analyze water quality scenarios in ArcGIS

Estimate total remaining effort required to achieve water quality goals

Non-Spatial results guide further GIS analysis

Landuse Data

Calculate

Baseline Load

Develop

Projects

Calculate

Reduced Load

Non-Spatial

Analysis

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ALERT Process: Calculate Baseline Loads


Calculate

Baseline Loads

Landuse Data

• Polygon layer attributed

with pollutant loading

and runoff information.

• lbs/ac/yr

(Loading Rates)

• mg/L

(Event Mean

Concentrations)

Baseline Loads

• Total annual pollutant

loads (lbs/yr) are

calculated.

• Simple Method

calculations consider:

• Impervious area

• Runoff coefficients

• Annual precipitation

either

Esri UC2013 .

ALERT Process: Develop Project Database


Project

Database

etc…

Water Quality Projects:

Pond Retrofit, 65 acres

Nitrogen Efficiency: 15%

Runoff Reduction: 0%

Cost: $275,000

Bioretention, 5 acres



Cost: $110,000

Redevelopment, 10 acres



Cost: Undetermined

Stormwater BMPs

Landuse Changes

• Treatment area

polygons

• Pollutant removal

and runoff reduction

efficiencies

• Other relevant

information

Esri UC2013 .

ALERT Process: Calculate Load Reductions


Iterates through project database, calculating and tracking pollutant and runoff reductions.

Baseline Loads

Reduced Loads (new polygon layer)

Detailed Results (pollutant reductions from each project)

Project

Database

Calculate

Load Reductions

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Baseline Loads

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Reduced Loads

Treatment

Area


Landuse

City of Alexandria, VA Potomac River Basin

15.4 square miles

Population: 144,301 (2011)


Landuse (MS4)

Identified areas draining to the

City’s Municipal Separate Storm

Sewer System (MS4).


Baseline Loads


Baseline Loads BMPs

Proposed BMPs included pond

retrofits, new ponds, bioretention,

and projected redevelopment.


Reduced Loads BMPs


Reduced Loads

Esri UC2013 .

ALERT Process: Non-Spatial Analysis


Baseline Loads

Reduced Loads Reductions

Non-Spatial

Analysis

• Results from GIS analysis

can feed into a non-spatial

component.

• Non-spatial ALERT tools are

used to roughly estimate the

remaining effort needed to

meet water quality goals.

• Project needs

(acres of treatment)

• Capital and annual

maintenance costs

• Total area of required

additional treatment is back-

calculated based on pollutant

reduction targets.

Esri UC2013 .

ALERT Process: Non-Spatial Analysis


1. Project Mix % by Area

Bioretention 10%

Filtration 10%

New Ponds 30%

Pond Retrofits 50%

2. Target

Pollutant Phosphorus

3. Results

Treatment Area 145 acres

Initial Cost $3.5 m

Annual Maint. $81,000

Baseline

Target

Reduced

Phosphorus

Baseline

Target

Reduced

Nitrogen

Baseline

Target

Reduced

Sediment

Pollutant Loads (lbs/yr)

Results are used to guide further GIS analysis.

Esri UC2013 .

Closing Thoughts

1. GIS tools make planning

stormwater treatment:

• Easier

• More cost-effective

• More reality-based

2. Non-spatial analysis can be

informative, but requires

verification.

• Results should be regarded

as approximations.

• Ouputs guide further GIS-

based planning.

Esri UC2013 .

Thomas Williams, EIT, LEED AP

Water Resources Engineer

AMEC Environment & Infrastructure

[email protected]

More Information:

Image Credits

1. http://www.flickr.com/photos/particlem/

3733639670/sizes/o/in/photostream/

2. http://www.flickr.com/photos/thirteenofclubs/

3383558429/sizes/o/in/photostream

…

ALERT: AMEC Load Estimation and Reduction Tracking

Technology

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