Lightweight pipe fills heavy-duty need in Racine

It's not every year that a city in southern Wisconsin undertakes an $80-million expansion of its wastewater treatment plant (WWTP), but that's what the Racine Water and Wastewater Utilities system has done.

RACINE, Wis., Oct. 13, 2003 -- It's not every year that a city in southern Wisconsin undertakes an $80-million expansion of its wastewater treatment plant (WWTP), but that's what the Racine Water and Wastewater Utilities system has done. Racine, with its picturesque lakefront and harbor, is located on Lake Michigan between the Milwaukee and Chicago metropolitan areas.

The Racine treatment facility also serves outlying communities including Mt. Pleasant and Caledonia, towns that are growing, creating the need for this expansion.

"The other towns are already contributing to us, and we just signed a new contract that allows them to expand in their communities," said Joe Mandala, superintendent of the Racine treatment plant. "With additional money from those two communities, we are able to expand. It's currently the largest wastewater treatment plant expansion in the state."

With the $80 million, Racine has been building an extensive list of new structures and piping, including a 2.7-million gallon above-ground stormwater storage tank, an underground storage tank, a new solids processing building, a new ultraviolet light disinfection system, an anaerobic digester, three new clarifiers and more.

HOBAS Selected

The extensive new pipeline work at the plant uses various sizes of HOBAS centrifugally cast, fiberglass reinforced, polymer mortar (CCFRPM) pipe. One $3.95-million contract includes a 1,180-foot-long HOBAS pipeline, 72 inches in diameter, SN 36, to carry effluent from the big storage tank southward to a chlorination facility. Other HOBAS pipes in that contract are sections 84 inches and 54 inches in diameter.

Earth Tech Inc., of Sheboygan, Wis., is the engineer for the $3.95-million contract. "We gave the contractor an option for prestressed concrete pipe or HOBAS," said Steve Peterson, a senior project director with Earth Tech. "And the contractor chose HOBAS pipe.

"I used HOBAS on one other project and we liked it very well," Peterson added. "We get a good installation, and it meets our qualifications for exfiltration and infiltration. And with the 20-foot pipe lengths, the contractor seems to get satisfactory production rates."

Jeff Weakly, president of Super Excavators Inc., of Menomonee Falls, Wis., the contractor, said the firm chose HOBAS because it was less expensive than prestressed concrete pipe. Super Excavators had used HOBAS pipes on previous, highly successful projects, but this would be their first using direct bury.

Meeting Tough Conditions

Located along the banks of Lake Michigan, the excavation ranged from 15 to 19 feet deep. The conditions were treacherous because of the high water table, the presence of native sandy materials and an abundance of soil fill.

Super Excavators installed a dewatering well on the low end. To shield the trench, they used a trench box and drove large steel plates outside of it on each side. "That way, when we pull the plates, the trench box on the inside helps to hold the soil in place," explained Gregg Rehak, field superintendent with Super Excavators.

In spite of the difficult conditions, the pipe was successfully installed and exceeded the engineer's requirements.

How did the HOBAS pipe work? "It was nice because it was a lighter pipe to work with," said Rehak. "We're not dealing with the heavy concrete. If we had to nudge the pipe over to make an alignment, you could move it by hand. If it had been concrete it would require a machine. I also like the 20-foot pipe joints that speed installation."

Typical of most WWTP installations, the Racine project included a number of fittings such as elbows and tees. HOBAS also provided FWC wall rings to fit the HOBAS pipe into the walls of structures. These serve as the water stop connections between the manholes and the pipe.

HOBAS manufactured all of the fittings with the same material as the pipes to provide the same benefits. The fittings are joined to the pipeline with push-together FWC couplings which are factory assembled to one end of each pipe or fitting for ease of installation.

Typical of most WWTP retrofit installations, numerous fittings including elbows and tees were required for several reasons including abrupt direction changes through the existing structures. However, HOBAS pipe made it much easier for the contractor to accommodate two radius S curves in the 72-inch pipe. These gradual direction changes were handled by slightly offsetting individual pipe sections to adjust the angle without the need for fittings.

"I've seen HOBAS pipe used in Caledonia, but this is the first time we've used it at the Racine plant." said Mandala. The City is pleased with the HOBAS pipe. "We concurred that HOBAS was the way to go."

HOBAS pipe is manufactured in sizes from 18 inches to 110 inches in pressure and non-pressure classes. For more information, please contact HOBAS at 800-856-7473, 281-821-2200 or e-mail at info@hobaspipe.com. Facts are also available at www.hobaspipe.com.

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