City Council last month awarded a $572,000 design services contract associated with a planned multimillion-dollar upgrade of the city’s water treatment plant on Westfield Avenue.

The governing body approved AR-207-13 at its Oct. 15 regular meeting, awarding the contract to Hatch Mott MacDonald. The Iselin firm was chosen over two others that submitted Requests for Proposals: CDM Smith, $488,600 and GPM Associates, $271,000.

The city solicited five Requests for Proposals (RFPs) and received three. Hatch Mott MacDonald was recommended by the city’s engineers, Bohler Engineering, over the two other firms after a review process based on the firm’s knowledge of the plant, experience in designing membrane systems and expiernce with filtering systems.

The engineering firm presented plans last summer to address the city’s century-old water treatment plant and the looming water capacity deficit.

Funds for the professional services contract will come out a $1.4-million capital ordinance approved in August specifically for preliminary work on the improvements. The $16.6-million upgrade the plant will be paid off through interest-free financing via the state’s Environmental Infrastructure Trust, water rate increases to pay off the debt coupled with declining payments on the remaining years of the lease with United Water.