Council approves amendment to advance combined‑sewer separation feasibility work; study identifies multi‑phase approach
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Summary
Mount Vernon approved Supplement No. 5 to Wilson Engineering's agreement to expand alternatives analysis and preliminary design for a combined‑sewer separation feasibility study that aims to remove an estimated 3–6 megagallons per day of peak flow from combined sewer to stormwater.
The Mount Vernon City Council on March 25 approved an amendment (Supplement No. 5) to a professional‑services agreement with Wilson Engineering LLC to provide additional alternatives analysis and preliminary design for the city's combined‑sewer separation feasibility study.
Frank Reinhardt described the two primary alternatives the consultant explored and said further analysis supported a preferred approach: construct a new stormwater system while repurposing portions of the combined sewer for wastewater conveyance. The work includes a phased capital‑improvement plan consisting of up to 10 phases meant to reduce peak combined‑sewer flows by an estimated 3 to 6 megagallons per day.
Reinhardt said the amended scope is intended to avoid building additional utility footprints across private properties where possible by locating new storm infrastructure in public rights of way and to minimize the need for new easements. Council approved the supplement by voice vote.
The action authorizes further design and alternatives work; additional council approvals will be required for construction and property‑rights actions once the study defines preferred designs and phasing.
