Date post: | 14-Jun-2015 |
Category: |
Technology |
Upload: | clean-water |
View: | 105 times |
Download: | 1 times |
COST EFFECTIVE PRACTICES FOR CLEAN WATER
Hye Yeong Kwon, Executive DirectorCenter for Watershed Protection, Inc.
• 501c3, started in 1992; offices in MD, VA, PA, NY
What we do• Distill research into practical tools• Provide local watershed services• Train others to manage watersheds• Association/ membership services
Your first source for best practices in watershed/ stormwater management
Stormwater BMP Cost-Effectiveness StudyJames River Basin, VA
• Evaluation of all urban practices• Costs and pollutant removal• Case study in the City of Richmond
Methods: BMP Selection
• 34 urban practices– 26 CBP practices with approved efficiencies– 5 CBP practices with recently approved expert
panel recommendations– 2 CBP practices under review by expert panel– 1 additional practice reviewed: pet waste
programs• Status of CBP BMP review panels available on
Chesapeake Stat website
Methods: Cost Estimates
• King and Hagan (2011): Costs of Stormwater Management Practices in Maryland Counties
• Additional studies, data and assumptions used for pet waste programs, illicit discharge elimination, stormwater retrofits, and urban growth reduction
• Considered 20-year life cycle costs, including:– Design and construction– Land values and financing– Operations and maintenance
Methods: Cost-Effectiveness Formula
Cost effectiveness ($/lb) =Annual pollutant reduction (lbs)
Average annual cost over 20 years ($)
For TN, TP, and TSS:
Results: Most Cost-Effective Practices for Nitrogen Removal
1. Pet waste programs2. Illicit discharge elimination: sewer repair3. Illicit discharge elimination: cross
connections4. Forest buffers5. Urban stream restoration
Results: Most Cost-Effective Practices for Phosphorus Removal
1. Pet waste programs2. Illicit discharge elimination: sewer repair3. Illicit discharge elimination: cross
connections4. Urban stream restoration5. Forest buffers
Results: Most Cost-Effective Practices for Sediment Removal
1. Urban stream restoration2. Illicit discharge elimination: sewer repair3. Urban growth reduction4. Retrofit of existing dry pond (conversion to
wet pond or wetland)5. Vegetated open channels (A/B soils, no
underdrain)
Case Study
Three scenarios developed:1. Old CBP approved practices, no
implementation constraints2. Current CBP approved practices, with
implementation constraints 3. All practices, with implementation
constraints
Case Study
Initial estimates for stormwater pollution reduction in the City of Richmond = $305 million
$84 million$64 million$68 million
Illicit Discharge
A discharge to storm sewer system that is not composed entirely of storm water except permitted discharges and
fire fighting related discharges
Findings from recent studies27-40% of outfalls have dry weather flow
Average Dry Weather Flow "Hit" Frequencyfor 5 Mid-Atlantic Watersheds
0
20
40
60
80
100
120
Any Wastewater Tap water Washwater Bacteria (co-indicator)
Type of Indicator
Per
cen
t
57%
43%
Other activities
Removal of illicit discharges
Estimated percent of required total nitrogen reduction that can be met through removal of illicit discharges in Western Run
*Illicit discharge load estimates based on single grab sample
Sligo Creek required 79% reduction and 17% could met be through illicit discharge elimination
*Assumes 50K per repair for 47 repairs
**Assumes 100% of the water quality volume provided by treating 1" of rainfall
Cost Comparison
$0
$20,000,000
$40,000,000
$60,000,000
$80,000,000
$100,000,000
$120,000,000
Practice
Co
st Total Nitrogen
Total Phosphorus
Illicit discharge elimination is a cost effective approach to nutrient management
Why should governments get credit for something that they are required to do?
• Illicit discharges fall through the cracks of MS4 permits and Consent Decrees
• MS4 permit requirements and guidance for IDDE is deficient
• Pollution load from illicit sources has not been accounted for in the Bay Model – coordinated action and response is needed
• We need more tools in the toolbox
What are gross solids?
• Litter: Human derived trash such as paper, plastic, Styrofoam, metal and glass greater than 4.75 mm
• Organic Debris: Leaves, branches, seeds, twigs and grass clipping greater than 4.75 mm
• Coarse Sediments: Inorganic breakdown products from soils, pavement, or building materials greater than 75 microns (0.075mm), & fragments of litter and organic debris not included in the other two categories
Stormwater Gross Pollutant Filters
Cost Summary ComparisonAnnual cost to remove equivalent annual TN load
The cost-effectiveness of stormwater controls for nitrogen removal.
Practice Type of practice Equivalent Annual cost ($/lb N/IC1 ac)
Bag filter Structural $691
Bioretention (new, suburban) Structural $335-$6342,3
Wet pond (new) Structural $7334
Street sweeping Non-structural $1655
1 Based practice life expectancy of 10-years. 2 Costs for other practices based on King and Hagen (2011) over a 20-year period and an urban loading rate of 14.1 lb TN/acre. 3 Range represents a removal efficiency of 45% and 85% from Simpson and Weammert 2009. 4 20% removal efficiency for TN from Simpson and Weammert 20095 Berretta et al. 2011 expressed as lb N/year
Discharge Flow Types•Pathogenic & toxic discharges
•Sanitary wastewater•Commercial & Industrial discharges
•Nuisance & aquatic life threatening discharges•Landscaped irrigation runoff•Construction site dewatering•Automobile washing•Laundry wastes
•Unpolluted discharges•Infiltrating groundwater•Natural springs•Domestic water line leaks
Other ToolsStream RestorationMaintenance of Stormwater BMPsCrediting New from EPA/ CBPLow Impact Development/
Green Infrastructure