Clark's Creek Outfall Retrofit

Clark's Creek Targeted Outfall Retrofits - Completed 2016

The Clark's Creek Targeted Outfall Retrofit project addresses water quality improvements through installation of sedimentation and filtration devices at selected stormwater outfalls to reduce pollutant loading into the creek.

Clark's Creek, a three-plus mile creek, meanders through Puyallup and Pierce County. As a true urban stream, it is not able to maintain its health as a natural forested stream would. Clark's Creek has been identified to have high levels of sediment deposits, low dissolved oxygen, high fecal coliform, and elevated water temperatures. To solve these problems, plans called Total Maximum Daily Load (TMDLs) have been developed by Washington Department of Ecology the EPA. These plans require the City, Pierce County, and other involved groups to take action to make the waters in Clark's Creek better. For Puyallup, this means reducing untreated stormwater flows into the creek.

Funded in part by a Washington Department of Ecology water quality grant, this project installed a total of four water quality devices, effectively treating over 40 acres of residential stormwater runoff. Please read on to learn about the three Modular Wetland Systems installed in this project. The 4th water quality device, an EcoStorm Plus, was installed as part of the Meeker Creek Restoration project.

Project Details

Installation of the 1st of 3 of the city's Modular Wetland Systems (MWS) (stormwater biofiltration system) began in early February 2016 and completed in April 2016. This project installed water quality treatment devices in 3 locations along 7th Avenue SW, funded by a Department of Ecology grant and using stormwater utility funds for the required grant match. These 3 units treat over 30 acres of residential lot and street stormwater runoff, each year reducing (based on modeling data) annual pollutant loading to the stormwater system by:
  • 2 tons of sediment
  • 4 pounds of phosphorus
  • 50 pounds of nitrogen
  • 150 lbs of biological oxygen demand
Of the 3 units, 2 include above-ground plantings whose root systems support increased functionality of the systems.

Basin 4 in Place

This unit will have no above-ground plants.
Basin 4 in Place

Basin 1 MWS

This MWS will have above-ground plants.
Basin 1 Modular Wetland System