Cresthill engineer updates council on Grand Prairie Water Commission timetable, route and financing

City Engineer Ron Wiedemann told the Cresthill City Council on July 21 that the Grand Prairie Water Commission’s alternate water source program is moving from design and land-acquisition into construction planning, with local work along Gaylord and Cedarwood drives expected to begin in staged segments beginning in mid‑2026 and extending into 2029. The update focused on schedule, route, permitting, financing and city-level system improvements required to accept treated Lake Michigan water.

Wiedemann said the commission selected treated water from the City of Chicago and is transferring the 05/01/2023 Chicago–Joliet water supply agreement to the Grand Prairie Water Commission. “We are on track to bid the project out the first quarter of 2026,” he said, and described bidding and construction timing for the large transmission mains and receiving facilities that must tie into Cresthill’s system.

The update matters because Cresthill’s existing supply relies on eight shallow wells that have shown contaminants; the council joined the commission to obtain higher-quality, long-term supply and to address PFAS. Wiedemann said municipal work will include new receiving stations, booster pump stations and a 2.5-million-gallon ground storage tank the city must construct to meet acceptance criteria.

Wiedemann gave these financing details: the Grand Prairie share of construction is currently presented at about $1,446,000,000 (not including the City of Chicago portion, which brings the total closer to $1.5 billion), with planned financing from a federal loan closing this September (rate assumptions locked at about 4.5 percent for baseline calculations), Illinois SRF/state revolving funds at near 2 percent, and revenue bonds to be sold later. He said Shorewood provided a $20 million upfront contribution to the commission.

On local system work, Wiedemann said communities must provide at least two days of storage (an IEPA requirement) and do distribution upgrades, corrosion-control studies and nonrevenue‑water audits. He said some corrosion-control testing can take months and that the city will test how Lake Michigan water behaves in Cresthill pipes before decommissioning the existing well system.

The presentation described an expected construction method mix: “Most of it is open cut. There’s a few locations that will be bored underneath,” Wiedemann said, adding the project will be performed in short closed sections rather than closing entire corridors at once. He said the construction footprint in Cresthill will primarily run down Gaylord and Cedarwood drives and that the commission will acquire roughly 400 temporary and permanent easements and require permits or coordination with more than 250 agencies.

Council members asked technical questions including whether the main would cross under Renwick and how residents would be kept informed; Wiedemann and City Administrator Blaine Wing said the commission and the city are preparing outreach, including online construction maps and periodic social media updates. Wing said staff plan to post biannual updates specific to Cresthill to keep residents informed.

The council also approved a related procedural item: a resolution appointing City Administrator Blaine Wing as the alternate delegate to the Grand Prairie Water Commission’s Technical Advisory Committee so the city has a named backup representative for engineering meetings. The resolution passed on a roll call vote (see actions list). The engineer said the first tunnel extension work has a notice to proceed and excavation began in June for a 10‑foot diameter tunnel that will be about 120 feet below grade and scheduled for completion at the end of 2026.

Wiedemann and the mayor cautioned the council the large, multiyear project will present “hiccups” in construction, and they asked for continued intergovernmental coordination as land acquisition, easements and permits move forward.