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When ‘Old School’ is the Right School: Combined Grout, CIPP Effective Solution For Illinois City
The American Bottom, or Bottoms, is a Southern Illinois area of 175-square miles in the flood plain of the Mississippi River, protected from flooding by a system of levees and canals. The cities in the American Bottom, such as Granite City, IL (population 30,000), have to contend with seasonally high, fluctuating groundwater, which can have a disastrous effect on underground facilities like sewers.
“As the groundwater changes from high to low and back, it can actually shift sewers around,” explains Steve Osborn, P.E. of Juneau Associates, Granite City’s engineering consultants, “If there’s no flow, for example, sewers can float up and in very wet weather they can be compressed.”
The results have been dramatic for Granite City. “The fluctuation has had a drastic effect here, and sewer repairs have been needed for some time,” says Osborn, “High groundwater in the last two years has created sewer failures, sinkholes and even a few blocks of collapsed roads.”
Compounding the problem is the age of the sewers. Many of the larger diameter pipes haven’t had any major work done since installation, about 100 years ago. This all added up to a huge financial burden. Between 1970 and 1985, for example, Granite City spent an average of $600,000 annually on sewer repairs. “Our city had a $10 or $11 million budget at the time,” says former mayor Von Dee Cruse, as quoted in the April 1993 Municipal Review. “The sewer repairs just devastated us. Sometimes a single joint repair would cost $50,000, and then we would have to turn around and repair the same spot a few months later.”
So, with partial funding from the Environmental Protection Agency, Granite City recently completed a massive sewer rehabilitation project. Granite City Sewer Lining and Rehabilitation Project B rehabilitated 15,600 lineal feet of large diameter concrete pipe ranging from 72-inches up to 108-inches in diameter.
The smaller diameter sewer, up to 54-inches in diameter, was repaired with cured-in-place-pipe (CIPP) lining as part of Project A. But Project B, the large diameter pipe, was rehabilitated exclusively with chemical grouting at failing joints. “That’s unusual for this region,” says James Bohn, Walden Associated Technology Inc., the grouting contractor for the project, “Sewer grouting is sometimes considered ‘old school’ because more lining is being done these days. This is the first big grouting job in this area in about 15 years.”