Sep 14, 2015

Retention & Restoration

Virginia county incorporates BMPs to reuse & recycle storm water

This wet pond will be enhanced to increase treatment efficiency and facilitate r
The retrofit design of storm water outfall will improve the quality of water dis

Communities across the U.S. are challenged with meeting multiple regulatory requirements of the Clean Water Act, often while dealing with perennial budget constraints and interdepartmental issues. Identifying the most cost-effective approach to storm water management can be a struggle.

Storm water management has evolved over many decades from a focus on flood control in the 1970s to an understanding of habitat protection and the need to integrate sustainable design and green infrastructure within the last 15 years. Throughout this time, regulations and requirements have also evolved. In response to these requirements, local governments have established wastewater, storm water and drinking water utilities, and they have developed storm water management programs, floodplain management programs and erosion and sediment control programs. Some of these programs have been integrated under watershed management programs.

Due to its location in the Chesapeake Bay watershed, Chesterfield County, Va., is required not only to meet its Municipal Separate Storm Sewer Systems (MS4) permit requirements, but also to comply with stringent total maximum daily loads (TMDLs) and to manage its storm water system within a set budget. This case study presents an example of a holistic approach to regulatory compliance.

Situation

The county’s MS4 and TMDL compliance strategy focuses on sustainability, resiliency and aligning watershed/storm water needs with permit requirements to meet its economic development and infrastructure goals while protecting, preserving and enhancing the natural and built environments. The county’s underlying goal is to have an efficient, reliable and maintainable storm water infrastructure system. Effective management of this system and MS4 permit compliance is allowing the county to address pressing watershed quality and quantity concerns while achieving this goal.

Solution

The project approach to storm water management, permit compliance and watershed management incorporated the following:

  • Viewing storm water as a water resource asset to be managed for surface-water quality enhancement, reuse, irrigation, groundwater recharge and protection of environmental features.
  • Integrating regulatory requirements while leveraging all county activities to maximize credit for all efforts, thereby reducing compliance costs and optimizing environmental protection.

In order to minimize costs and achieve compliance, the county evaluated a combination of best management practices (BMPs) under different scenarios. Countywide pollutant loads and cost estimates were prepared for each scenario.

BMPs for the first permit cycle: Compliance during the first permit cycle (2015 to 2019) included the following baseline BMPs:

  • Existing BMPs completed after June 30, 2009. Any BMP's part of redevelopment can be credited toward Chesapeake Bay TMDL compliance.
  • Planned BMPs recommended through Capital Improvement Program (CIP) projects (FY15 to FY19). These BMPs include stream restoration, storm water outfall retrofits (e.g. sheet flow to vegetated filter) and green storm water retrofits in county-owned property (e.g. bioretention, swales, filtering practices).

These existing redevelopment and planned BMPs allow the county to comply with the load reduction requirements in the first permit cycle. Funding for these BMPs has come from existing programs, state grants from the Virginia Stormwater Local Assistance Fund and the county’s General Fund.

Additional BMPs for second and third permit cycles: Alternative scenarios were also used to estimate CIP project costs required to meet the load reduction requirements. These scenarios included differing mixes of the following BMPs:

  • Primary BMPs—stream restoration of selected portions of degraded streams.
  • Secondary BMP—lake restoration. Retrofit of an abandoned water supply reservoir into a BMP that meets current state criteria.
  • Tertiary BMPs—Various combinations of BMPs that include storm water outfall retrofits, green storm water retrofits and pond retrofits.

Results

The county is evaluating different alternatives to fund these BMPs and to address programmatic compliance requirements. Long-term, reliable funding for storm water programs continues to be a challenge for most local programs.

Scott Smedley, P.E., is director of environmental engineering for Chesterfield County, Va. Smedley can be reached at [email protected] or 804.751.2311. Fernando Pasquel is national director, stormwater & watershed management for Arcadis. Pasquel can be reached at [email protected] or 703.842.5621. Noelle Slater is senior environmental engineer for Arcadis. Slater can be reached at [email protected] or 757.419.3974.

Arcadis

Contact

630 Plaza Drive

Suite 200

Highlands Ranch, CO 80129

United States

Phone: 720.344.3500

Fax: 720.344.3535

http://www.arcadis-us.com

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