Aerated Sludge Holding Tanks

Charles County Board of Commissioners is requesting proposals for engineering design services for aerated sludge holding tank upgrades at the Mattawoman Wastewater Treatment Plant, with proposals due July 13, 2026 at 11:00 a.m. A mandatory site visit is scheduled for June 18, 2026 at 10:00 a.m. at 5310 Hawthorne Road, La Plata, Maryland 20646, and a non-mandatory pre-proposal meeting is June 17, 2026 at 11:00 a.m. via teleconference. Questions are due June 26, 2026 at 11:00 a.m.

The scope requires a qualified multi-disciplined engineering firm to prepare complete contract drawings and specifications, obtain all applicable permits, and provide construction engineering services to upgrade the tanks to achieve three days of storage capacity at 20 million gallons per day average daily flow. The design consultant must complete work within 420 consecutive calendar days from Notice to Proceed, progressing through 30%, 60%, 90%, and 100% design phases plus bid-phase and construction-phase services. Construction-phase services include 24 monthly progress meetings, 16 site visits, substantial and final completion inspections, review of 120 shop drawing submittals, 50 Requests for Information, and 15 Proposed Change Orders over an estimated 24-month construction period. All work must comply with NFPA 820 standards and applicable county and regulatory requirements.

The estimated total project cost is $1.5 million, with initial FY 2026-2027 phase estimated at $350,000. Funding splits 85% Charles County and 15% WSSC. The cost proposal comprises three lump-sum base items (Design Phase Services, Bid Phase Services, and Construction Phase Services on hourly basis), a $150,000 Design Services Contingency, and allowance items totaling $25,000 for test pits and topographic survey. Progress payments cap at 90% of contract amount with the remaining 10% upon final completion.

Offerors must demonstrate design of a minimum of four relevant projects over the past ten years with at least one completed detailed design of aerated sludge holding tanks of similar capacity and at least one completed through construction, each with total construction cost exceeding $10 million. Required key personnel include a Principal (15 years engineering experience, PE Maryland), Project Manager (10 years, PE Maryland), Architect (10 years, AIA registered Maryland), Senior Design Engineer (12 years, PE Maryland), Design Engineer (7 years, EIT or PE Maryland), and Process Engineer (15 years WWTP design experience, PE Maryland).

Proposals are evaluated on project understanding (15 points), experience of key staff (30 points), firm experience and representative projects (15 points), and price (40 points). Proposals remain valid for 120 days from due date. GHD is ineligible due to prior County engagement. Submissions are electronic via the County's eProcurement Portal at https://procurement.opengov.com/portal/charlescountymd.