CITY OF EAST CHICAGO RAW WATER PIPELINE - MICROTUNNELING IN CLEAN SANDS BENEATH THE WATER TABLE

摘要

To meet increasing demand, the City of East Chicago is constructing a new water treatment plant(WTP) designed to treat raw water from Lake Michigan. As part of the overall project a 900-foot gravity pipelinewas required to convey raw water from an intake structure to the new WTP, which has been successfully constructedusing microtunneling techniques. A 72-inch internal diameter Permalok steel casing was utilized for installation ofthe 48-inch internal diameter Hobas carrier pipe. The pipeline was constructed in two separate trenchless driveswith Drive 2 being the longest and most sensitive. Drive 2 was approximately 760 feet in length and completedthrough clean, poorly-graded sand below the groundwater table. The drive passed beneath seven sets of railroadtracks spanning approximately 140 feet; multiple utility lines that included water, electric, gas, andtelecommunications up to 48 inches in diameter; and approximately 300 feet of Indiana Department ofTransportation right-of-way including a highway off-ramp, with associated shallow foundations, and both the northand south bound lanes of Cline Avenue. Due to the propensity for settlement when dealing with running andflowing sands, an extensive geotechnical instrumentation program was conducted during mining. This paper willfocus on the steps taken by the Owner, Engineer, and Contractor to form effective relationships with the utility andrailroad companies to reduce the probability of ground movements, including the use of Drive 1 to troubleshoot andeliminate issues/problems with means and methods before performing Drive 2.