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Use of Voluntary StormwaterCredit Program for
Encouraging StormwaterSensitive Practices
EPA Region 6
Don McChesney, PE
Aiza Jose, PhD, PE, LEED AP
June 2012
Don McChesney, PE
Aiza Jose, PhD, PE, LEED AP
June 2012
MS4 Operators Conference
Outline
• Background
• New Approach to Stormwater Management
• WQ and LID - iSWMand Fee Credit Policy
• Problem Statement & Objective
• Methodology
• Case Studies2
Background – City of Fort Worth
• Fort Worth population
– 2011 740,000
– 2030 1,200,000, ,
• Low taxes
• Limited regulations
• “All American City”
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Background – Stormwater Funding
• Public safety priority
• Mandatory design it i Fl dcriteria – Flood
Protection
• Voluntary – Water Quality Guidelines
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Background - Stormwater Funding
• Stormwater utility established in 2006 after severe flooding
• Budget
– 2006 $7.6 M
– 2012 $31 M
• Funding
– Fees charged to developed properties (impervious cover)
– Credit System to reward BMPs
• CIP - $40M/yr currently
• Water quality not major driver6
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• 2006 Ordinance created stormwater fee and reference credit program
• Credit Program not
Background - Stormwater Funding
established until 2010
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Stormwater Management Approach
Traditional – Flood control : conveying
Stormwater away from urban i kl iblareas as quickly as possible
– Current issues: increased Stormwater flows (reduced infiltration), velocities, pollutant loading and erosion
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Lake Worth
New Stormwater Management Approach
Future – Holistic approach: address
water quality (pollutant load) and quantity (flood control) i t t h d l lissues at a watershed level
– Consider green infrastructure and Low Impact Development
– Analyze options that achieve multiple benefits
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John Tidwell MS
– Consider local characteristics and specific problematic
– Effective solutions will be site specific: No “one-fits-all” solution
New Stormwater Management Approach
CHALLENGES:
Improving underground drainage systems is difficult
– Streams often conveyed in
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yundersized pipes
– Natural topography ignored
– Large drainage systems
– Upsizing these large trunk lines can be prohibitively expensive
New Stormwater Management Approach
OPPORTUNITIES:
• Look for open space in flood-prone areas
• Make incremental detention improvements over long term as opportunities arise
• Design for multiple purposes– Stormwater: flood protection & water quality
– Amenities: attractive, useful & maintainable
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Water Quality & Sustainable Design
Current Initiatives:• Integrated Stormwater Design
Manual (iSWM)
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• City Credit Policy
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Water Quality & Sustainable Design
• iSWM– State of the art standards
adopted for Low Impact Development (LID) in 2006 –iSWMiSWM
– Use of LID is voluntary
– Water Quality Volume (WQv)
– 85 percentile storm 1.5 in runoff
– 24 h detention
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Fee Credit Policy
• Water quality treatment (25%)
• Channel protection detention
• Industrial Permit Compliance
• Inlet Trash Collection (10%)
Up to 40% Credit for sustainable practices
detention
• Detention maintenance
• Zero Discharge
• Student Education
• Inlet Trash Collection (10%)
• Parking Lot Sweeping(5%)
• Adopt-A- Creek (5%)
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Credit to individual impervious areas, rather than site as a whole
Runoff must be treated to iSWM standards
Water Quality & Sustainable Design
• City Credit Policy – Water Quality– 25% Credit
70% removal TSS– 70% removal TSS
– Performance measured as per iSWM standards
– Still under development for interpretation,credit determined on a site-by-site basis
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Problem Statement
• Water quality and LID are voluntary
• iSWM design criteria and credit policy are still developing
• Limited local experience in design for local engineers and architects
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In response, Fort Worth adopted a proactive approach to promote applications that made sense environmentally, socially and economically using the CREDIT POLICY
Objective
• Promote Sensitive Stormwater Management Practices
– Improve water quality
– Feasible ($)($)
– Functional (O&M)
– Attractive
– Recognize/Reward
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Methodology
• Identification of existing practices through the use of a consultantconsultant
• Minimal retrofitting
• Recognize/Reward
• Refine design criteria & streamline credit policy
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Methodology
• Ideal Candidates Schools
– Large footprints
– Green areas
Outreach opportunity– Outreach opportunity
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Methodology
• Sensitive Practices
– Wet ponds
– Grass channels
– BioswalesBioswales
– Rain Gardens
– Porous pavement
– Grass pavers
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Case Studies
• 9 case studies
– Feasible ($)
Functional & Maintainable– Functional & Maintainable
– Attractive
Wet Pond
Total Credits: 24%Annual Savings: $8,160Timber Creek High School
Dry Pond
Wet Pond
Charles Baxter Middle School
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Total Credits: 25%Annual Savings: $2,138
Dry Pond
Grass Pavers
Dry Pond
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Brewer High School
Wet Pond
Total Credits: 5%Annual Savings: $1,769Additional “Grass Pavers” $2,980
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Cornersone
250-Gal Rain Harvesting Barrels
Grass Channel
Adopt-A-Creek Program
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Cornerstone Baptist Church
Infiltration Trench
Total Credits: 21%Annual Savings: $675
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Green Roof
Grass Sidewalk
Bioswales
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Botanical Research Institute of Texas
Total Credits: 23%Annual Savings: $894Additional (Green Roof, Porous Pavement) $972
Porous Pavement
Grass Pavers
Grass Channel
Wet Pond
Wetland Area
Outfall
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Wetland Area
Dry Pond with Wetland
Grass Swale
John Tidwell Middle SchoolTotal Credits: 25%Annual Savings: $2,414
North Side High School
• Annual Fee :$3,267
• Grass Channel/Bioswale
• Total Credits: 25%
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• New Monthly fee: $2,449/yr
• Annual Savings: $818/yr
A few other case studies…
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Total Credits: 9%Annual Savings: $507Retrofits: $500
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Bioswale
Rain Garden
Rain Garden
Saw Tooth Curbs
Raised Inlets
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Bioswale
Bioswale
Bioswale
Cost Analysis
Cost
• Filter Bed Soil
• Parking Blocks
Savings
• Piping (length & size)
• Curb and Gutter g(Sawtooth Curbs)
• Plants
• Riprap
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Potential Net Savings $100,000•Total Credit: 25%•Annual Savings: $1,345
Curb and Gutter
• Inlets
• Concrete Vault
Questions
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Aiza Jose, PhD, PE, LEED APBrown & Gay Engineers, Inc.