MELROSE PARK, Ill. (CBS) — The transformation of Chicago’s McCormick Place is a stark reminder of the strain on hospitals during the COVID-19 pandemic.

A total of 500 beds are on standby at the sprawling convention center to treat mild cases of coronavirus. Now, the work has moved on to transforming buildings that had once been hospitals into treatment center.

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CBS 2’s Steven Graves got an inside look Sunday at how that is coming together in Melrose Park.

Contractors packed the old Westlake Hospital, wearing masks. It is a race against time to assess the mechanics of a building that will provide care for those patients with more serious cases of COVID-19.

“Time is our real driver,” said Col. Aaron Reisinger of the Army Corps of Engineers.

Westlake will be what is called an “alternate care facility.” As recently as last August, it was an active hospital – and now it will strictly treat COVID-19 patients.

“These are not going to be hospitals where you can drive up to the front door and be seen in the emergency room,” Reisinger said.

Instead, the Westlake emergency room has a new setup – and could take in those coming from other hospitals.

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We got an inside look, and saw desks piled up in rooms and trays in walkways. There are areas that need a lot of work, but make an ideal space for treatment.

“There are many rooms that are already piped for med gas for example to be able to bring in inline oxygen which is really important for our moderate to high acute patients,” Reisinger said.

That is what sets the facility apart from McCormick Place that is taking in patients with mild cases.

The Advocate Sherman Hospital campus in Elgin and MetroSouth Medical Center in Blue Island have also joined the list of old medical facilities ready for a revamp. The goal is to treat up to 350 patients at Westlake at its capacity.

The tricky part, again, is time – on a project that could take weeks. Graves asked about the urgency to get patients in as COVID-19 numbers steadily increase.

“Our goal is exactly what you said – try to create some capacity early and turn it over. The challenge is whether or not we can effectively do that, do patient care here, and continue to construct.” Reisinger said. “We’re finding that’s kind of complicated in the other two facilities we’re working on.”

Construction is expected to start on Monday, with an opening date in about three weeks.

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The Federal Emergency Management Agency is paying for the project. The Army Corps of Engineers is also a week into construction at the hospitals in Elgin and Blue Island.