Aerated Sludge Holding Tanks

The Charles County Government, through its DPW - Capital Project Management division, is soliciting design services for critical upgrades to the Aerated Sludge Holding Tanks at the Mattawoman Wastewater Treatment Plant, which serves portions of Charles and Prince George’s Counties. The existing tanks, originally designed as aerobic digesters, currently function as flow equalization units and lack sufficient capacity to meet the county’s requirement for three days of storage at the plant’s 20 million gallons per day average daily flow. The project requires a qualified, multi-disciplined engineering firm to deliver fully permitted, bid-ready design documents and construction engineering services to reconfigure and expand the tank system to achieve this capacity target. Key technical upgrades include replacing existing blowers with new positive displacement blowers, installing a CAMix aeration system, repurposing Tank 2 for scum storage and Tank 5 for thickened sludge, installing a new digested sludge pump, applying self-priming polyurethane coatings for structural integrity, and integrating new controls and sensors into the SCADA system. All design work must comply with county specifications and include acquisition of necessary permits, development of construction documents, and oversight through the construction phase. The contract is structured into three main phases—Design, Bid, and Construction—with separate pricing for each, and includes a $150,000 design contingency and allowances for test pits and a topographic survey. The solicitation, numbered 26-041, is open to electronic submission only via the OpenGov Procurement portal, with proposals due by July 13, 2026, and must be accompanied by technical documentation on SF330 forms and a separate cost proposal with all pricing rounded to the nearest cent and inclusive of overhead, profit, and transportation. Proposals must demonstrate proven experience with at least four to five similar wastewater treatment projects over the past ten years, including one completed aerated sludge holding tank design of similar scale and another constructed project with a total cost exceeding $10 million. The award will be based on a weighted evaluation of price (40%), key staff experience (30%), project understanding (15%), and firm capability (15%), with no guarantee of award to the lowest bidder. Contractors must provide performance and payment bonds, labor and materials bonds, and carry insurance including $5 million umbrella coverage, $2 million environmental liability, $1 million pollution liability, and cyber insurance with $1 million per occurrence limits, along with professional liability coverage