City of Allegan

Allegan Water Treatment Plant

Project Description

The City of Allegan considered retrofitting or rehabilitating its water treatment plant for years, but struggled with the cost and complications of improving its lime-softening system within the confines of an old building. In addition, the site of the water plant, which drew the area’s water supply from three wells, was in a floodplain that flooded frequently.

Despite these challenges, Allegan built a new water plant — Michigan’s fist lime-softening to Reverse Osmosis (RO) conversion project.

Design Challenges

Allegan’s existing treatment system used lime softening. P&N studied the situation and recommended that Allegan construct a new Reverse Osmosis plant on the same site. The new 2.3 MGD plant uses reverse osmosis and iron removal for treatment. It includes a new 0.5 MG ground storage tank, a solar panel roof, and an on-site mixed oxidant generation system.

The new plant was constructed on the same site as the former plant, but unlike its predecessor, it rests above the 500-year flood plain. The MDEQ approved P&N’s proposal to raise the site four feet to prevent future flooding in exchange for removing lime lagoons on the site and extending the floodplain.

An asset of the plant’s site is its proximity to the Kalamazoo River, which is the discharge location for the RO concentrate, a byproduct of the RO treatment process. Allegan also renewed its NPDES discharge permit as part of the project.

The final plant design included three iron filters, three RO skids, five high-service pumps, and five chemical feed systems. A new well was drilled on the site, and the existing wells were retrofitted with submersible pumps.

The Result

“We got a state-of-the-art water treatment facility for a fraction of its value and a much-improved site,” said Ray Berkin, Allegan Water Treatment Plant Superintendent.


Mark Prein, PE
Project Manager


In 2008, local pharmaceutical manufacturer Perrigo announced plans to expand its facility, which would require additional water supply. Because this addition would bring more jobs to the area, P&N used the situation to help Allegan acquire a $3.7 million EDA grant for a new water plant.

The remainder of the $10 million project was funded through a low-interest loan from Michigan’s Drinking Water Revolving Fund program. Allegan also received 40% loan forgiveness on this loan through the federal stimulus program.


American Council of Engineering Companies (ACEC) of Michigan Merit, 2012