Tennant Way Stormwater Low Impact Development Improvements

Client—City of Longview, Washington

Gibbs & Olson is providing design phase services for this stormwater Low Impact Development (LID) project. The Tennant Way corridor is the gateway approach into the City from Interstate 5 and has the third highest average daily traffic volume in the City. The main objective of this stormwater project is to showcase LID techniques and demonstrate to the public the connection between the built environment and water quality. This project will implement stormwater LID retrofits that will reduce runoff volume, remove stormwater runoff pollutants, and improve corridor aesthetics. Proposed elements of the streetscape design include the conversion of on-street parking areas into bioretention planters and other drainage improvements, replacement of asphalted center medians with green medians, consolidation of driveways, incorporation of pervious sidewalks and ADA ramps as applicable, and replacement of portions of water and sanitary sewer lines.

The Tennant Way corridor is zoned commercial and mixed use commercial/industrial, and a portion serves as a designated truck route. The Longview ditches receive stormwater runoff from the Tennant Way corridor. Water in these ditches is ultimately pumped to the Columbia River. Water quality within the ditches has been identified as problematic and broad adoption of LID stormwater techniques will help improve the area’s water quality.