North Plant Blower Installation

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

The blowers at the North Plant consisted of two unused 400 horsepower (Hp) blowers installed in 1976 and one 250 Hp blower installed in the early 1990s. TRRWA worked in conjunction with the Cowlitz PUD and Bonneville Power Administration to evaluate the existing facilities and look for possible efficiency improvements and potential savings in operating costs. The installation of a new aeration blower at the North Plant was identified as a way to achieve these goals. Gibbs & Olson reviewed the existing Scope Assessment Report and provided design engineering services to prepare contract documents, technical specifications and design drawings for procurement and installation of the equipment components.

The project included: installing a new 150 Hp direct drive blower with integral variable frequency drive, installing dissolved oxygen (DO) probes and associated control equipment to control the speed and output of the blower based on the amount of DO in the aeration basin cells. Electrical and control system wiring and programming were installed as required to automate the DO control system. The installation also provides user access to adjust setpoints through the plant’s programmable logic control system.