Argonne Rd - Wellesley Ave to Upriver Dr Drywell Retrofit
Stormwater Retrofit Project
Spokane County Stormwater Utility's Argonne Road Stormwater Retrofit Project took place in the spring of 2015. The project was a water quality project and is located in east Spokane County (north of the town of Millwood) in a highly urbanized area within a high ADT (24,854) Urban Principal Arterial roadway., The start of the 3/4 mile project is located approximately 400 feet from the Spokane River.
The project involved installing treatment structures, in the form of sand filters, ahead of existing drywells in a portion of Argonne Road where untreated stormwater was being intercepted and directly injected into the sandy subsoils below the drywells in a highly susceptible aquifer protection zone. The new treatment takes stormwater runoff from the roadway, sidewalks and hydraulically connected driveways. 15 drywells were retrofitted with 16 new sand filters, intercepting approximately 4 acres of pollutant generating impervious surface (PGIS) to provide pretreatment of stormwater.
Pretreatment of stormwater runoff benefits our community by helping to purify runoff that may ultimately reach the Spokane/Rathdrum Prairie Aquifer, the sole source of drinking water in our region.