draft chesapeake bay tmdl action plan public meeting

A Fairfax County, VA, publication

Department of Public Works and Environmental Services

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Draft Chesapeake Bay TMDL Action PlanPublic Meeting

December 14 and 15, 20161

Draft Chesapeake Bay TMDL Action Plan

Key Definitions and Acronyms• MS4 – Municipal Separate Storm Sewer System

– Area draining to stormwater outfalls owned or operated by the County that discharge to surface waters

– Subject to an MS4 permit under state and federal law– Issued for five-year terms, although may be administratively extended; the most recent permit was

issued April 1, 2015• Impaired Waterbody

– A waterbody that does not meet water quality standards based on monitoring data– Listed in accordance with Section 303(d) of the federal Clean Water Act

• TMDL – Total Maximum Daily Load– The maximum amount of a pollutant that a waterbody can receive and still meet water quality

standards– A TMDL generally establishes the existing load and the target load. It then allocates the load

reduction among sources– The allocation is divided into a load allocation (LA) and a wasteload allocation (WLA)

• TMDL Action Plan– The MS4 permit requires the County to develop plans for how it intends to achieve the required

pollutant load reductions

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Example MS4 Components

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1 Downspout2 Untreated runoff

5 Stormwater outfall6 Urban stream

3 Storm drain4 Sewer system

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Stormwater Management

Bay TMDL Background – A Long, Winding Road

• Voluntary interstate effort formalized by 1983 Chesapeake Bay Agreement

• Shift from voluntary to regulatory – lawsuit and 2010 Chesapeake Bay TMDL

• Pollutants of Concern (POCs): nitrogen, phosphorus, and sediment

• Means and methods in place to clean up the Bay by 2025



Impacts of Nutrients and Sediment on the Bay

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Algae Bloom Caused by Excess Nutrients

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Sediment from Hurricane Isabel

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Chesapeake Bay TMDL

“The TMDL – the largest ever developed by EPA – identifies the necessary pollution reductions of nitrogen, phosphorus and sediment across Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia and sets pollution limits necessary to meet applicable water quality standards in the Bay and its tidal rivers and embayments.”

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Virginia’s Plan for the Chesapeake Bay

• Virginia Watershed Implementation Plan (WIP) Phase I and II• Allocates POC reduction targets based on the Bay Model:

– Wastewater– Agriculture– Urban/suburban stormwater– Onsite wastewater (septic systems)– Forest lands– Resource extraction– Federal facilities

• Virginia’s challenge – it can only require reductions for entities subject to permits or regulations.

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Fairfax County’s Two-Pronged Approach

• Meet the MS4 permit requirements:– Delineate MS4 service area as of 2009 (base year for reductions)– Delineate impervious and pervious surfaces within the service area– Use information to calculate required POC reductions

• WIP milestones: 5% of reduction targets by 2020; 40% by 2025 and 100% by 2030

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11Stormwater Management


Fairfax County’s MS4



Bottom Line – Required POC Reductions

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Nitrogenlbs/year

Phosphoruslbs/year

Sedimentlbs/year

5% by 2020 2,959.42 323.42 263,865.57

40% by 2025 23,675.36 2,587.36 2,110,924.56

100% by 2030 59,188.4 6,468.4 5,277,311.4



Before there were specific Bay TMDL requirements…

• Fairfax County developed watershed management plans for each of the County’s 30 watersheds

• Plans identify and address issues affecting water quality

• Include policies and projects• Many of projects in the plans

have been leveraged to meet the Chesapeake Bay TMDL

• Plans can be found at www.fairfaxcounty.gov/dpwes/watersheds/

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Key Components of the Action Plan

• Detailed guidance provided by the Virginia Department of Environmental Quality (DEQ Guidance Memo 15-2005)

• New development:– No net increase in phosphorus load:

Fairfax County Stormwater Management Ordinance (July 1, 2014)

– Address increases from 2009 to 2014– Make up for increases from

grandfathered projects• Means and methods to reduce POCs

from existing development

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2009-2014 Development – A funny thing happened…

• MS4 permit requirement – offset increase over 16% impervious cover (0.45 lbs/phosphorus/acre/year)

• County requirements during this time period:– 40% phosphorus removal for new development County-wide– 50% for new development in the Water Supply Protection Overlay District– 10% for redevelopment County-wide– Exemptions for large lot subdivisions and infill development

• What does that all mean?

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Pollutant TN(lbs/year)

TP(lbs/year)

TSS(lbs/year)

Increase from New Impervious Cover 1,202.69 174.30 81,782.93Reduction from Stormwater Facilities 1,610.69 404.12 196,603.22Net Reduction (Credit) 408.00 229.82 114,820.29Percent Total (Year 2030) Target 0.7% 3.5% 2.2%

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Means and Methods – Key Considerations• The County has been preparing for a while!

– Stormwater retrofits since 2009– Stream restorations since 2010

• Credit for past actions not captured in the Bay Model– 2006 to 2009 stormwater facilities

• Credit for going above regulatory minimums– Nutrient management plans– Single family residential development under one acre

• Project selection process:– Watershed management plans and other inputs– Technical feasibility– Community support– Ability to address local impairments– Cost-benefit ratio

• MOU with Herndon and Vienna



Historic BMPs – 2006 to 2009

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 5,705.48 670.27 577,628.02Percent Total (Year 2030) Target 9.6% 10.3% 10.9%



Stormwater Retrofit Projects

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TP(lbs/year)

TSS(lbs/year)



Click icon to add picture


Stream Restoration

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 17,446.58 5,438.31 1,832,406.33Percent Total (Year 2030) Target 29.4% 84.0% 34.7%



Land Use Change

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 37.27 0.54 207.31Percent Total (Year 2030) Target 0.1% <0.1% <0.1%



In-Lake Forebay Projects

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TP(lbs/year)

TSS(lbs/year)




Redevelopment

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) Coming Soon Coming Soon Coming SoonPercent Total (Year 2030) Target NA NA NA



Single Family Residential Under One Acre

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 135.32 22.09 11,977.54Percent Total (Year 2030) Target 0.2% 0.3% 0.2%



Septic Conversion

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 1,806.85 -- --Percent Total (Year 2030) Target 3.0% 0.0% 0.0%



Nutrient Management Plans

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TP(lbs/year)

TSS(lbs/year)

Net Reduction (Credit) 89.58 1.82 --Percent Total (Year 2030) Target 0.2% <0.1% 0.0%



Other Means and Methods

• Additional means and methods that the County may take credit for in the future:– Parking lot sweeping– Off-site nutrient credits (purchased or transferred from wastewater

treatment facilities)– Home owner practices such as downspout disconnection, tree planting,

rainwater harvesting, nutrient management plans, etc.

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Current Permit Compliance Snapshot

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Total Nitrogen (lbs/year)

Total Phosphorus (lbs/year)

Total Suspended Solids (lbs/year)

Required Reductions from Existing Sources 2,959.42 323.42 263,865.57+ Required New Source

Offsets -408.00 -229.82 -114,820.29+ Required Grandfathered

Offsets 56.27 8.11 3,727.09= Total Required Reductions and Offsets for Current Permit Cycle

2,607.69 101.71 152,772.37

- Means and Methods from Section 5 36,874.71 7,076.57 3,294,038.21

= Reductions Remaining for Current Permit Cycle -34,267.02 -6,974.86 -3,141,265.84Credit Applied to Next Permit Cycle 34,267.02 6,974.86 3,141,265.84



Total Compliance – Year 2030 Target

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TN

TP

TSS

0.0% 20.0% 40.0% 60.0% 80.0% 100.0% 120.0%Structural Retrofits Stream Restoration 2006-2009 Redevelopment SFR 2009-2014

SFR Post 2014 PL 566 Dams Septic Conversion Off-Site Credits NMPs

Land Use Change Other New Source Credits

63.0%

112.8%

64.6%

203020252020

Cost To-Date = ~$79 Million



Uncertainties, Challenges, and Next Steps

• Remaining POC Reductions– Still must achieve additional ~40% reduction in nitrogen and sediment– Several projects in-design or being scoped– Fewer easily accessible stream restoration projects

• 2017 Mid-Term Assessment and WIP Phase III– Changes in POC reduction targets?– Changes in target dates?

• Local TMDL Action Plans for Sediment– Higher local reduction targets– Bull Run, Difficult Run, and Popes Head Creek

• Project Maintenance– Credits will expire if projects are not maintained

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Next Steps

• Public comment period will run through January 23, 2017• Draft plan and responses to comments will be presented to

the Board of Supervisors’ Environmental Committee on February 7, 2017

• Plan must be submitted to the Virginia Department of Environmental Quality by March 31, 2017

• Draft plan is available at: http://www.fairfaxcounty.gov/dpwes/stormwater/chesapeake-bay-tmdl.pdf

http://www.fairfaxcounty.gov/dpwes/stormwater/chesapeake-bay-tmdl.pdf

http://www.fairfaxcounty.gov/dpwes/stormwater/chesapeake-bay-tmdl.pdf

Additional Information and Comments

For additional information or to submit comments

www.fairfaxcounty.gov/dpwes

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Kate Bennett, MS4 Program Coordinator(703) 324-5500

Mailing address: MS4 Program Coordination SectionStormwater Planning Division, Fairfax County DPWES12000 Government Center Parkway, Suite 449, Fairfax, VA 22035-0052

E-mail address: [email protected]

mailto:[email protected]

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