Stormwater Program Support for Tumwater

Herrera developed a plan to guide the City of Tumwater’s stormwater program for the next 5 to 10 years. We evaluated the City’s existing program, then made recommendations to ensure it would comply with regulations and to position the City for future permit requirements. We also reviewed the City’s list of stormwater capital improvement projects (CIPs), completed field assessments of problem areas, and developed designs and cost estimates for new CIPs. With our project partner, we assessed program implementation costs and developed a utility rate structure that meets the City’s most urgent needs. While developing the stormwater plan, Herrera revised the City’s stormwater design manual, bringing it to current standards. The manual includes robust requirements for LID, simplified submittal requirements, and additional wellhead protection measures—and addresses several elements unique to Tumwater, such as seasonally high groundwater, unmanaged impervious surface, and cumulative stormwater effects of multiple developments.