This project consisted of installing new drainage structures; including catch basins, piping and drywells; in a neighborhood area that regularly saw roadway flooding during runoff events. The new structures were installed along 63rd Avenue, near the intersections of Helena Street, Martin Street, and Crestline Street. The goal of this project was to decrease the frequency and extent of roadway flooding and add sediment storage capacity to increase the required maintenance interval of these drainage structures. Construction of this project was completed by NNAC Inc. under the supervision of Spokane County Stormwater Utility in November 2018.
The existing drywells in this area were found to be in a failed state when flooding conditions persisted after cleaning and other maintenance practices were performed. Seven new double-depth drywells were installed with pipe connections from existing drywells. Three new catch basins were also installed at desirable locations to decrease surface flows and add sediment removal capacity prior to water entering drywells. The existing drywells were left in-place to retain available runoff storage volume and add another layer of sediment storage upstream of the new drywells. Funding for this project was provided by the Stormwater Utility and was completed using Spokane County’s Small Works Roster program.