Sewer Vactor Dumping & Drying Bed Facility

Client—Three Rivers Regional Wastewater Authority (TRRWA), Washington

The Three Rivers Regional Wastewater Authority selected Gibbs & Olson to design a new vactor dumping and biosolids storage facility at the regional wastewater treatment plant. The vactor dumping and dewatering portion is a regional facility that serves Cowlitz County, the cities of Kelso and Longview, Beacon Hill Water & Sewer District, and can be utilized by private entities The new facility includes: a five bay vactor dumping station with appropriate containment facilities to accommodate an annual estimated 500,000 pounds of dry material; drain and pump system to convey all runoff to the treatment plant; and two biosolids mixing and storage bays. The entire facility is covered by an 80 foot by 120 foot pre-engineered metal building. Gibbs & Olson provided design and construction phase services including siting, sizing and layout of the dumping bays and biosolids storage bays.

The new dumping bays include a sloped reinforced concrete floor accessible by a front end loader to remove the dry solids material. The sloped floor conveys water that drains out of the spoil materials to a drainage collection system. The drainage is then pumped via a submersible pump station to the existing drainage system for the plant which then directs flows to the headworks. Reinforced concrete push walls will be utilized around the sides and back of the drying beds to keep material from spreading or flowing off the drying bed area when a vactor truck is emptied.