Middle Potomac Watershed Plan Implementation

Dead Run Stream Restoration Project

Public Meeting

McLean Community Center

April 23, 2014

Stormwater Planning DivisionDepartment of Public Works and Environmental Services

Meeting Outline

• Fairfax County Stormwater Management• Countywide Watershed Plan Implementation• Project Introduction and Objectives• Existing Conditions• Proposed Improvements - Options• Example Projects• Questions?

Fairfax County Department of Public Works and Environmental Services (DPWES)Department of Public Works and

Environmental Services

Land Development

Services

CapitalFacilities

Solid Waste Stormwater

Stormwater Planning Division

Maintenance and Stormwater

Management Division

Wastewater

Stormwater Infrastructure

• Conveyance System– 1,600 miles of pipe and

paved channel– 43,000 structures– 6,800 outfalls

• Management Facilities– 1,540 county maintained – 3,720 privately maintained

• State Regulated Dams

A typical outfall

A dam in Fairfax County

Service Drivers

In response to The Clean Water Act of 1972

National Pollutant Discharge Elimination System (NPDES)

Virginia Stormwater Management Program (VSMP) Regulations

Municipal Separate Storm Sewer Permit (MS4)

Total Maximum Daily Loads (TMDLs)Chesapeake BayLocal Streams

Countywide Watershed Planning

“Healthy Watersheds, Healthy Communities”

• 30 Designated Watersheds

• All 15 watershed plans have been adopted by Fairfax County

http://www.fairfaxcounty.gov/dpwes/watersheds/

Middle Potomac Watershed Plan

• Watershed Characterization– Water Quality Monitoring– Land Use Change– Pollutant Loading

• Structural Project– 25 Year Plan

• Non-Structural Practices– Policy and Regulationshttp://www.fairfaxcounty.gov/dpwes/watersheds/

Dead Run Watershed Plan

• Dead Run has a drainage area just over 3 square miles

• 24 priority projects identified in the watershed management plan• Pond retrofits• LID Stormwater Enhancements• Stream Restoration• Neighborhood Stormwater

Improvementshttp://www.fairfaxcounty.gov/dpwes/stormwater/projects/project_list.htm

Approximately one third of the roof is covered with vegetation. The benefits of a “living roof” include:

• Reduces the amount of stormwater runoff• Absorbs air pollution and carbon dioxide• Reduces the energy needed to cool the building in summer

Partnership: LID Stormwater EnhancementsDolley Madison Library

Vegetated Roof- Delosperma and Allium plants in bloom

Partnership: LID Stormwater EnhancementsDolley Madison Library

Sustainable Site Design

Dead Run – Before and After

Drainage Area(acres)

Phosphorous Removal(lbs/yr)

Nitrogen Removal(lbs/yr)

Sediment Removal(tons/yr)

415 15 283 3

Stream Restoration

Dead Run – Stream Restoration

Stream Monitoring Program

Study Objectives

1. Generate long-term monitoring data.

2. Evaluate relations between observed conditions/trends and BMP implementation.

3. Transfer the understanding gained to other less-intensively monitored watersheds.

http://va.water.usgs.gov/projects/ffx_co_monitoring.htm

Dead Run Stream Restoration

Dead Run Stream Restoration

Segment 1 – Dominican Retreat• 2,000 Linear Feet

• Extends to Old Dominion Drive

• Residential lots along Merrimac Drive and Van Ness Court

Dead Run Stream Restoration

Segment 2 – McLean Central Park• 800 Linear Feet

• Completely in Park

• Starts below previously restored section near library

Dead Run Stream Restoration

Segment 3 – McLean Central Park

• 1,500 Linear Feet

• Extends to Churchill Road

• Residential lots along Elizabeth Drive and Carol Rayes Street

Next Steps

• Conceptual Design• Land Acquisition/Coordination• Preliminary Design• Public Meeting• Final Design• Project Construction

• Funding FY2016 and FY2017• Community Coordination: Pardon Our Dust

• Maintenance and Operation

Natural Channel Design

Background and Design Approach

Stream Design Approaches Natural Channel Design

3 design approaches 1)Analog 2)Empirical 3)Analytical

Segment 1

Dominican Retreat

Segment 2 & 3

Mclean Central ParkDead Run Stream Valley Park

Alternative Access

Alternative Access

Instream Structures

Looking upstream at boulder rock toe and constructed riffle

Looking upstream at boulder rock toe – 2 and 3 courses

Modified Cross Vane

Modified Cross Vane

Cross Vane Cross Vane

Cross Vane

Step Pool

Infill mix comprised of cobbles, gravels, sand, silt, topsoil

Larger material, usually cobble

Constructed Riffle(aka Reinforced Streambed)

Riffle

Access

During May 2010

BeforeFeb. 2010

AfterSept. 2010

John Palmer

John.Palmer@fairfaxcounty.gov

Dipmani Kumar Dipmani.Kumar@fairfaxcounty.gov

Matt Meyers

Matthew.Meyers@fairfaxcounty.gov

Stormwater Planning Division

Department of Public Works and Environmental Services

Fairfax County12000 Government Center Parkway, Suite 449

Fairfax, Virginia 22035

Questions ?

Contact Information

A Fairfax County Publication, April 2014

To request this information in an alternate

format call 703-324-5500, TTY 711

www.fairfaxcounty.gov/dpwes/stormwater

Thank You!