The City of York operates a 26-mgd advanced wastewater treatment plant, providing service to the greater York region. As part of its sludge handling processes, the City employs anaerobic digestion and combusts the accumulated biogas to produce electricity to meet the facility’s needs. To ensure optimal performance of the biogas piping, the City hired RETTEW to design and construct improvements to the valving and instrumentation of the biogas system. RETTEW removed and replaced four biogas header valves, added biogas isolation valves on the roofs of three digesters, installed flow meters for the waste gas flare lines, cleaned header line locations, and created safety procedures for proper venting and purging of accumulated biogas.

With an integrated safety team handling construction oversight, RETTEW developed a detailed staging plan to minimize disruptions to the operation of the anaerobic digestion facilities and ensure proper fire protection during the construction period. Additionally, as a portion of the plan involved venting of uncombusted biogas, RETTEW handled permitting modifications with the Pennsylvania Department of Environmental Protection to ensure all required recordkeeping was executed in conjunction with the improvements.