Efficient, Economical Grout Solution For Downers Grove

Reducing Sewer Line I/I With Grouting Allows Sanitary District To Avoid Major Expense
April 2014, Vol. 69 No. 4

The Downers Grove Sanitary District (DGSD) is located in Downers Grove, IL, a community located 25 miles west of Chicago. The District serves 20,000 residential and business customers in Downers Grove and surrounding communities.

Like many Midwestern communities that were founded in the 1800s and grew over the succeeding century, its sewer system contains pipes of a wide variety of ages, from as old as 109 years to much more recent additions made as the service area grew. Replacements have been made as the existing infrastructure has aged. Today the DGSD system covers 20 square miles with 252 miles of sewer (consisting mainly of eight-inch vitrified clay pipe) and nine lift stations, and is designed to handle a peak flow rate of 110 million gallons per day.

When the American Recovery and Reinvestment Act of 2009 (ARRA) made funds available for “shovel-ready” infrastructure projects, the DGSD proposed a project to seal, by means of chemical grouting, a part of its system to reduce infiltration and inflows (I/I). The targeted 15 basins include 112,000 linear feet of eight- to 24-inch unlined pipe. The goal of the project was to seal 24,600 mainline joints, 3,100 lateral connections and 440 manholes. Work on the project began in December 2009 and was completed in August 2010.

Sewer stress

All parts of a sewer system – main sewers, laterals and manholes – are subject to the normal stresses of ageing and wear on materials and stresses on joints that lead to increasing I/I of storm water and ground water into the system. Materials carried into the sewer by the incoming water reduce the working diameter of the pipes at the same time that the I/I is increasing the volume of water that flows through the sewer. The result is increased stress on the capabilities of the sewer system and increased cost of treatment to system users.

Sewers are also subject to external, less predictable extreme stresses such as excessive flows during heavy storms that overload storm sewers. Overflows from storm sewers added to the increased pressure of ground water increase inflows into wastewater sewers, but also direct water into supporting trenches that erodes the supporting earth and gravel under sewer lines.
Supporting material is washed away, either into the sewer itself or along the supporting trench.
“Without proper support, pipes can then begin to shift,” states Frank Aguilar, vice president, customer service and operations of Avanti International, manufacturer of the grout used in the project, “causing gaps at joints and even failure of the pipes themselves.”