what we do


Developing best management practices

Stormwater management practices and regulations have advanced rapidly in recent years. To reduce the impact of built areas, Parametrix uses low impact development (LID) principles and practices. Our solutions optimize the use of on-site natural features to improve water quality, protect habitat and wildlife, reduce life-cycle costs, and enhance communities. We apply the latest technologies to provide clients better ways to manage stormwater.

Manchester Stormwater Retrofit | Parametrix
Manchester Stormwater Retrofit
Manchester, Washington
Client: Kitsap County

An empty lot in Manchester now does double duty as a pleasant community space and a workhorse to clean polluted runoff for Puget Sound. The Manchester Stormwater Park is the Puget Sound area’s first stormwater park, and one of only a few such combined treatment/recreation facilities in the nation. The project was initially designed to replace an aging and undersized outfall. However, Kitsap County recognized a unique opportunity to treat a larger drainage area and correct some flooding issues as well as enhance the community. The Stormwater Park treats stormwater from roads, parking lots, commercial property, and residential areas from approximately 100-acres upland of downtown Manchester to today’s strict standards through innovative Green Stormwater Solutions (GSS) using soil and plants. Treatment cells located around the perimeter of the park process storm flows through engineered filter media and plants that can tolerate periods of inundation, and also clean the runoff using filtration and absorption processes. A unique design feature of the park is a spiral rain garden that intercepts low flows from groundwater and very light storms and treats it through bioretention soil mix and plants in the rain garden. Because the rain garden intercepts the relatively constant low flows, the life of the more expensive engineered treatment media in the treatment cells will be extended. Treated water is collected in a lower drainage system and subsequently discharged to a new outfall at the beach in Pomeroy Park.

  • 1st Place, Small Population Category, NAFSMA, 2016
  • Vision 2040 Award, Puget Sound Regional Council, 2016
  • Honor Award, ACEC 2016
  • Project of the Year - Environmental Less than $5M, APWA Washington Chapter, 2016
  • Gold Award, Waste and Storm Water, ACEC Washington, 2016



  • Manchester Stormwater Retrofit | Parametrix

    Manchester Stormwater Retrofit

  • NPDES Stormwater Management Program  | Parametrix

    NPDES Stormwater Management Program

  • Surface Water Comprehensive Plan Update | Parametrix

    Surface Water Comprehensive Plan Update

  • Newberg-Dundee Bypass | Parametrix

    Newberg-Dundee Bypass

  • Duwe’ig Stormwater Treatment Wetlands | Parametrix

    Duwe’ig Stormwater Treatment Wetlands

  • Parametrix Stormwater - SR 520 Bridge Replacement and HOV Program, Seattle to Redmond, Washington

    SR 520 Bridge Replacement and HOV Program


"Over the past year I have had the pleasure of working with the Parametrix team on the City's Storm and Surface Water Utility Comprehensive Plan Update. This has truly been a collaborative effort... working alongside city staff from a variety of departments and programs in addressing policy, regulatory and natural resources challenges."

Brian Ward, PE, Utilities Engineer, City of Bellevue, Washington