The City of Boise's Digestion and Dewatering Project: Making the Most Out of Your Existing Assets, How to Maximize Your Existing Digestion, and Dewatering Facilities and Eliminate the Need to Build New Infrastructure

Many utilities today are faced with the responsibility of operating and maintaining facilities while deciding where to best apply limited capital resources to aging facilities. The question of 'Do we build a new facility that we will own and operate for the next 20 to 50 years or do we consider upgrading the existing infrastructure/technologies?' is one we all grapple with as limited funds are allocated to capital projects. The effective utility management strategies used here will be of use to other municipalities and utilities considering major capital improvement projects while making the most out of their existing assets. With an initiative to make well informed financial decisions, what started out as a project to construct a new digester changed into an effort to analyze the root process problems and identify several alternative approaches to upgrade the existing digestion and dewatering process, thus postponing the need for a fourth digester for the foreseeable future. However, constructing a new, green field digester and making the connections to the existing digestion system at the end of the project may cause much fewer disruptions to the operations of the facilities compared to a surgical approach of retrofitting and improving the existing system. Under these conditions, it was paramount to develop a team approach that identify early any impacts to operations due to the systems component's removal from service, and the need to maintain operations and permit requirements while making significant modifications to the existing digestion system.