Client: Simpson Timber Company, Shelton, WA.

Project Specifications: Simpson Timber Company operates sawmills in Washington and California producing dimension lumber. This project at the company’s 400-acre Shelton facility involved two key on-site improvements at the Simpson Mill #5 and log-sorting yard. The first was mitigation of localized flooding affecting the areas around the mill during heavy rains. The second was ensuring that the facility as a whole met Department of Ecology stormwater discharge standards.

To meet those goals, Hatton Godat Pantier provided full stormwater retrofit design services, including engineering of detention, treatment and conveyance systems.

Key Challenge: Although the Simpson Timber sawmill’s production technology was “cutting-edge,” the ground adjacent to the log yard often turned into a mud pit during heavy rains. The runoff drained into a storm pond, which emptied out into a local creek. Though serviceable, the system was at risk of running afoul of state environmental regulations and needed to be significantly upgraded.

The Point of Difference: “We engineered a system using large settling ponds and a ‘decanting’ process to settle out suspended particulates – i.e., mud,” said Steve Hatton. “After the redesigned system was engineered and constructed, the client was able to meet strict state and federal NPDES guidelines for stormwater discharge.”