Ecology Stormwater Retrofits

The City of Sumner was awarded two Department of Ecology’s Stormwater Grants to design and construct a system retrofit to Basin J, which is a 770 acre mixed commercial and residential area tributary to the White River, along with Basin A2, and a 170 acre residential area that includes a portion of SR 510 that is a tributary to the Puyallup River.

When it was determined that an end-of-pipe treatment was not feasible, due to the lack of available right of way and funding, a detailed basin assessment determined that both upstream drainage basins had treatment facilities installed with previous development. This allowed KPG to complete a site evaluation and prioritization analysis that focused on roadway and sub-basin retrofits.

Our work included stormwater sampling to target possible sources of contamination for treatment. In addition, all listed filtration devices were evaluated based on construction costs, overall facility size and annual maintenance needs. This work allowed KPG to provide preliminary and final design of an arterial stormwater retrofit along 2,600 LF of E Valley Highway in northeast Sumner in Basin J and a media filter system constructed on Maybell Street to treat runoff from a 94 acre tributary area in Basin A2. The final design included 18 Filterra units and three 10 foot x 20 foot and two 8 foot x 16 foot Modular Wetland units.

KPG also provided construction management services for this project under a separate contract.