Curlew Flooding Evaluation and Stormwater Improvements
Spokane, WA
When it Rains, it Pours. But when it Really Pours, Varela Determines how to Handle the Stormwater.
On May 2, 2016, the Indian Trail residential neighborhood in northwest Spokane experienced an unusually heavy rainfall that overwhelmed the City’s drainage system, resulting in extensive flooding and severe localized erosion to residential properties. The heavy rainfall and lack of adequate drainage caused property damage including loss of backyard property and landscaping, basement flooding, damage to a backyard pool as well as damage to City streets and the drainage system. Neighborhood residents met with the City to develop an action plan.
Recommendations Based on Observation and Modeling
Curlew experienced stormwater flooding at several locations along River Street in downtown Curlew. The flooding over the years has damaged multiple properties; including the Ansorge community building and the Riverside Restaurant. Sandbags were routinely used to keep storm water from entering buildings; and often ponding would reduce available parking and was a constant nuisance for the community. Additionally, stormwater runoff would routinely overflow untreated into the Kettle River adjacent to Curlew.
Varela conducted a stormwater flooding evaluation and recommended improvements that include: installation of stormwater collection system; grading and road improvements; and installation of a treatment system to treat stormwater runoff. Multiple treatment configurations and options were evaluated; the selected method included a ConTech stormwater filter treatment unit system. The stormwater evaluation was completed in accordance with the Stormwater Management Manual for Eastern Washington (SMMEW).
The improvements recommended were funded through Ferry County Federal RTPO funding. The project and improvements were coordinated with Curlew’s sewer collection system construction project. Partnership between the two allowed for a single contractor to complete both projects. Shared costs allowed for a cost-effective project within Ferry County’s available budget.
Project elements include:
Field reconnaissance and historical highwater and flooding assessment
Stormwater evaluation and hydrological modeling; conveyance and treatment recommendations
New stormwater collection system for the downtown area
Design of a modular stormwater treatment system sized to accommodate tight space requirements in the downgradient area of downtown Curlew
Construction of the stormwater improvements coordinated with Curlew’s sewer collection system project for cost savings
After construction of the improvements: In 2018, Ferry County experienced one of its largest flooding events in nearly 100 years. Curlew Community reports the improvements installed as part of this project were a lifeline and prevented significant damage and issues for the community.
Key Project Staff: Daniel Cowger
