Meeting the Chesapeake Bay TMDL

Transcription

1 Meeting the Chesapeake Bay TMDL Local Stormwater Perspective Presented by Rob Hopper, PE Developed with Mike Morgan, PE September 14, 2015

2 Chesapeake Bay TMDL Local Stormwater Perspective Virginia Stormwater The ChallengeLocal Assistance Fund (SLAF) Required Local Investment Looking Ahead

3 EPA determined pollutant load allocations and reductions needed for each major watershed. Chesapeake Bay TMDL Each state was responsible for developing a Watershed Implementation Plan (WIP) to achieve the reductions.

4 Virginia Implementation Schedule 2005 April 2010 District of Columbia MS4 Permit Feb Dec EPA Establishes Chesapeake Bay TMDL Jul 2013 Dec Arlington County States to meet 1 st Virginia 60% of pollutant Phase I MS4 load reduction Permit Virginia Revised Phase II MS4 Permit Requirements 2025 States to meet 100% of pollutant load reduction

5 Municipal Separate Storm Sewer System (MS4) Permit Cycles to Achieve Full Pollutant Reduction 5% 1 st 5 Year Permit 35% 2 nd 5 Year Permit 60% 3 rd 5 Year Permit

6 Virginia s Estimated Funding Need Source: Report the Virginia Senate Finance Committee (11/18/2011)

7 Typical Pollutant Reduction for Existing Development in Virginia Land Area Pollutant Reduction per 1,000 acres (lb/yr) Impervious 800 TN Pervious 400 Impervious 200 TP Pervious 40 Impervious 133,400 TSS Pervious 8,800

8 Retrofit Options and Removal Rates Conversion Converted to a different BMP with a more effective treatment mechanism Enhancement Increase treatment volume or retention time Schueler, T, C. Lane, Recommendations of the Expert Panel to Define Removal Rates for Urban Stormwater Retrofit Projects. Chesapeake Stormwater Network. Baltimore, MD. Restoration Renew performance through major maintenance, upgrade or replacement

9 Data Collection and Desktop Assessment Existing BMP type and function Tributary area delineation Pervious area Impervious area BMP Volume GIS Existing volume 95% capture volume

10 Candidate Site Selection Site Assessment New Development Utility Impacts Environmental Impacts Utility Impacts

11 Retrofit Options and Removal Rates Pollutant Removal Incremental Removal Existing Proposed Runoff Volume Treated Modified from Recommendations of the Expert Panel to Define Removal Rates for Urban Stormwater Retrofit Projects (2012)

12 Screen options to identify feasible retrofits Impervious tributary area is key Conversions are typically top performers Look for opportunities to increase tributary area Retrofit Recommendations Some sites are not suitable for significant retrofit Prioritize with cost effectiveness Differentiate planning and site specific preliminary design

13 Tributary area Total Area = 179 acres Impervious Area = 119 ac Example 1 Expand Existing Wet Pond Storage Existing 3.6 acre feet 0.4 inches Proposed 8.4 acre feet 0.9 inches

14 Tributary area Existing = 6 acres Proposed = 30 acres Existing IA= 3 acres Proposed IA = 21 acres click Example 2 Convert Small Dry Pond to Wet Pond Storage Existing 0.9 acre feet 3.9 inches Proposed 4.8 acre feet 2.8 inches

15 Tributary area Total Area = 90 acres Impervious Area = 41 acres Example 3 Restore Existing Wet Pond Storage Existing 5.0 acre feet 1.5 inches Proposed 7.7 acre feet 2.3 inches

16 click 530 Linear Feet of Urban Stream Enhancement Example 4 Urban Channel Enhancement 0.6 acres of Riparian Wetland Variable Width Buffer Enhancement

17 Summary of Retrofit Benefits and Costs Site Pollutant Δ Removal (lbs) Example 1 (Enhance) TN 140 TP 30 TSS 11,300 Total Project Cost Cost per Impervious Acre $360,000 $3,030 Example 2 (Convert) TN 90 TP 20 TSS 7,900 $260,000 $8,500

18 Summary of Retrofit Benefits and Costs Site Pollutant Δ Removal (lbs) Example 13 (Enhance) (Restore) TN TP 30 6 TSS 11,300 2,600 Total Project Cost Cost per Impervious Acre $360,000 $230,000 $3,030 $5,680 Example 4 (Stream) TN 3 TP 36 TSS 130,000 $370,000 N/A

19 Large Centralized Solution Holistic Watershed Approach Maximizes Community Benefits Linear Roadway Solution Evaluate Watershed Characteristics Identify Opportunity Areas to provide costeffective solutions Potential Enhancements

20 Identifying Project Opportunities New football stadium, new performing arts center, 24 acres of development could benefit 275 acres of existing development ODU Foreman Field, New football stadium, new performing arts center, 24 acres of development could benefit 275 acres of existing development

21 Virginia Funding by BMP Type (SLAF 2014) Wetland $1,580,000 Bioretention $25,000 $10,085,000 Swale $7,000 GI $980,000 $10,260,000 Bioretention Green Infrastructure Pond Stream Restoration Swale Grant Funding: $22.9 Million Total Project Cost: $45.8 Million Wetland

22 Annual Funding to Treat Existing Developed Areas Estimated Cost ($/yr) $300 $250 $200 $150 $100 $50 Per Household $ Year Per Person *Land acquisition will drive costs even higher

23 Chesapeake Bay TMDL Tracking

24 Data Collection and Desktop Assessment

25 Questions Rob Hopper

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27 Annual Funding to Treat Existing Developed Areas Previous studies: Florida Department of Environmental Protection Center for Watershed Protection Virginia BMP retrofit designs FDEP data: Basis of nutrient removal costs: Total Phosphorus Average cost $25,000 per pound per year for P 50% design, permitting and contingency

28 Ranking Criteria Pollution reduction Cost effectiveness Impaired water bodies Fiscal stress Readiness to proceed Phase II MS4s Pollutant Removal Virginia BMP Clearinghouse Expert Panel Recommendations Virginia Stormwater Local Assistance Fund (SLAF) Stormwater Local Assistance Fund Selection Differentiators Focused on phosphorus removal Funding threshold: $50,000 per pound removed Project Cost Capital Cost O & M Cost Project Lifecycle Cost