During the reconstruction project of two water transmission mains for the City of Akron,rnOhio, contaminated groundwater was discovered in an open trench. This incident delayed therncontinuation of the project until a method could be developed and plans prepared to complete thernconstruction of this portion of these vital mains. The following paper describes the design,rnmaterials, and procedure used to successfully replace a pair of antiquated steel transmissionrnmains through a 160 m (525 ft) long area containing heavy petroleum contamination.rnCompletion of this section of mains restored full operation of the water transmission mainrnsystem and allowed the replacement project to continue. Prior to the design of all majorrntransmission main projects, it is recommended that environmental exploratory studies bernperformed.rnAkron's water supply treatment facility is located at Lake Rockwell, about 18 km (11 mi)rnaway from the city. Three parallel large-diameter transmission mains, one 900 mm (36 in), onern1,200 mm (48 in) and one 1,350 mm (54 in) diameters, deliver over 152 million liters (40 mg) arnday to the city's intown reservoirs. Peak summertime pumpage is usually about 213 millionrnliters (56 mg) a day. Akron also sells water wholesale to two smaller communities from thesernmains along their routes. With these constraints, only one transmission main can be taken out ofrnservice at a time for replacement or emergencies while continuing to meet the city's water needs.rnTwo of the three transmission mains, the 900 mm (36 in) and the 1,200 mm (48 in), werernsteel and constructed parallel to each other between 1913 and 1921. A third transmission main,rnof prestressed concrete, was installed between the plant and the city along a different routernbetween 1955 and 1965. By the 1970s, a former electrified railway, aggressive soils, and roaddeicingrnsalts had caused extensive pitting on the steel mains, resulting in hundreds of leaks.rnRepairs were frequent and troublesome.rnIn 1982, after physically examining and evaluating both steel mains, a consultant reportedrnthe pipe's poor condition to be a threat to the city's continuity of water supply and recommendedrnthat 11.3 km (7 mi) be replaced. The city immediately undertook a major capital program tornrebuild the worst portions of mains within Akron and its neighboring community, Tallmadge, inrnfive successive phases. Plans for the first phase of parallel 1,200 mm (48 in) prestressedrnconcrete mains, mostly along roadway edges, were prepared. Later, bids were let, a contractor
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