Centerville council advances wastewater plant upgrade design, schedules work session on outfall options

The Centerville Town Council on Aug. 7 approved a $2,446,672 contract amendment to fund full design of an upgraded wastewater treatment plant and heard staff updates on studies for a proposed outfall into the Corsica River.

The project team presented a preferred membrane bioreactor (MBR) technology and preliminary results from a computer mixing study for a proposed outfall extension. Council and staff agreed to hold a work session at 5:30 p.m. on Sept. 4 to review irrigation‑versus‑outfall alternatives, funding scenarios, and implications for an in‑progress rate study.

Neil, a KIPP representative who presented the technical update, said the town had submitted an amended preliminary engineering report (PER) to the Maryland Department of the Environment (MDE) after MDE asked for additional justification of the selected alternative. He told the council the project team completed cold‑weather water‑quality sampling on the Corsica River and is doing warm‑weather sampling now, and that a computer mixing model has produced preliminary (not final) results on bacteria and temperature impacts of a proposed 1 million‑gallon‑per‑day outfall alignment.

Why it matters: the council is weighing two broad approaches to reducing permit exceedances and meeting future demand — expanding the plant and extending an outfall into the Corsica River versus land‑based irrigation or farm reuse. The outfall has materially different permitting and cost consequences; the MBR produces lower bacterial concentrations in effluent, and model results will inform whether an outfall location can provide adequate dilution while avoiding impacts to restricted shellfish areas.

Key details from the presentation and council discussion: - Technology and studies: presenters recommended a membrane bioreactor (MBR) on technical and public‑perception grounds, noting the MBR’s fine filtration substantially reduces bacteria levels before discharge. The team has completed cold‑weather baseline sampling and is conducting warm‑weather sampling; a Corsica River mixing model is near completion and will be reviewed with MDE and Maryland DNR in the coming 6–8 weeks. Neil said the team could not publicly release final mixing results until they are finalized and reviewed with agencies. - Cost estimates: the PER includes separate cost lines for the treatment upgrade and a potential outfall extension. The presentation noted an overall estimated program figure that can exceed $50 million if an outfall is included; the outfall alone was described as being in the range of “$14 million plus” in the materials presented. Staff said the presentation includes a 30% contingency customary for this stage of preliminary design and used a 4% annual escalation estimate for out‑year cost inflation. Presenters noted the outfall and plant construction are separate permitting and engineering efforts. - Funding and schedule: the council approved amendment No. 4 to the engineering contract with Whitman, Requhart and Associates (design firm name in packet: Whitman Reichardt and Associates) for $2,446,672 to complete the design phase. Staff said $2,155,000 of that amount will be covered by a congressionally directed spending grant and that the town must provide a 20% match (approximately $431,000) to be budgeted in FY27, potentially from a combination of town and state funds. The design phase was presented with an estimated 14‑month schedule and a proposed start date of Sept. 1, 2025 if approved. - Alternatives and next steps: several council members pressed for continued evaluation of irrigation/land application alternatives and for a holistic comparison (land purchase, conveyance pipelines, pump costs, and long‑term operations). Staff agreed the farm/irrigation option remains under consideration but noted that irrigation also requires conveyance infrastructure and has distinct permitting/engineering implications. Council members emphasized urgency because the town recently approved a rate study and because an impending turnover in council seats in October will leave new members to review technical material.

Council action and schedule: the council voted to award contract amendment No. 4 (design only) to Whitman Reichardt and Associates for up to $2,446,672, funded primarily from a congressional earmark with a required town match. The council also scheduled a work session at 5:30 p.m. on Sept. 4 to dive deeper into alternatives (outfall vs. irrigation), grant opportunities, and rate impacts before the next regular meeting.

What council did not decide tonight: no final decision was made on the outfall alignment, the final mixing study results remain under agency review, and the council deferred a more detailed comparison of irrigation/land application versus an outfall to the Sept. 4 work session. Staff repeatedly described some cost figures as preliminary and subject to change as designs and agency feedback progress.

The council said staff and its lobbyist will continue pursuing state and federal funding, and staff will return with more detailed agency feedback after the MDE/DNR review of the mixing study.