New water purification facilities constructed by J.S. Alberici Construction Co., Inc., in Milwaukee, Wisconsin, will ensure the safety of the city's water supply.

The Milwaukee Water Department has taken steps to protect the city's water after more than 100 people died in 1993 from drinking water contaminated with the organism cryptosporidium.

One of the largest steps is the installation of facilities to inject bacteria-killing ozone into the water at two of the plants. Alberici, in conjunction with the design firm Black & Veatch, took on this $48 million design/build project on a fast-track basis and completed the job last July. It is currently the largest retrofit ozone facility in the world and has the ability to treat 425 million gallons of water per day.

At the two plants, Alberici installed facilities that produce ozone to kill the cryptosporidium and inject it into the water supply. New equipment (manufactured by Ozonia, Inc., Lodi, New Jersey) at the plants produce ozone by subjecting liquid oxygen to an electrical charge. The ozone is released into the water basins. Ozone is then removed from the water as it leaves the basins and moves through the treatment process.

In the design/build concept used on this project, the designer and contractor were on the same team from the beginning. This eased the burden on the project owner, who then could deal with a single design/build team rather than separate companies. It smoothed out the permitting process as well, since the designer and contractor approached permitting together.

The team worked with the owner to save money on the project through changes in the design. For instance, at one site working space for construction was tight. The team changed the direction the building faced in order to make access to the site easier.

"Our success on this project demonstrates the effectiveness of the design/build process," said Gary Gossett, Alberici's vice president overseeing the Milwaukee work. "We own our equipment and operate our own steel fabrication facility so we have greater control in staying on schedule."

In other steps to protect the water supply, the water department extended its intake line further into Lake Michigan, lessening the likelihood of pulling in parasites that generally breed close to shore. In addition, sand and gravel filtration at the treatment plants has been replaced with crushed anthracite filters for more effective screening.

The city's health department has been regularly testing the water supply for cryptosporidium. Even so, the absence of the parasite during these tests does not ensure the safety of the water supply. The new facilities should eliminate any uncertainty.