The City of Warner Robins (City) owns the 9 million-gallon-per-day (mgd) Sandy Run Creek WPCP. In May 2008, the City received a new NPDES permit for the facility with significantly lower effluent limits, including BOD and ammonia. The City initiated the process to select a consultant to design the upgrades to the WPCP and, using a competitive procurement process, selected a large national engineering firm. However, the City was not happy with the recommended improvements, the treatment process, and the costs, resulting in the dismissal of the consultant.
In June 2010, the City contacted Constantine Engineering to prepare a new Design Development Report (DDR) and permitting documents to upgrade the WPCP and to evaluate an expansion of the plant to a capacity of12 mgd. During the DDR development, which was completed by July 2010, it became very clear that an expansion of the WPCP was necessary since the facility was operating at greater than 80% capacity. The new DDR included the costs to upgrade and expand the WPCP to 12 mgd, and included 3-stage biological nutrient removal process that included treatment to remove ammonia and total phosphorus. The estimated costs to expand the WPCP were $29.5-million, and included the new BNR process and deep bed sand filters.
Constantine contracted with the City in June 2011 to develop 30% design documents and to manage a construction manager at risk (CMAR) procurement process. The final design and construction contract was completed and construction began in August of 2012. Construction was substantially complete by December 2015 and the final construction cost was $30.7 million, a number that included additional scope items.