Pipeline construction avoids forest destruction.
WHEN the State of Indiana needed to install a force sewer main from the Branchville Training Center, a minimum security prison, to Tell City 18 miles away, there were two possible installation routes. One was through Hoosier National Forest, where construction and maintenance of the 87,000-ft pipeline would cause permanent destruction of forestland. The alternative was along the shoulder of Route 37, a "cut and fill" limited-access state highway that bisects the park and continues on to the Tell City wastewater treatment facility.
After reviewing a design study, Indiana approved the $2-million roadside installation of high density polyethylene (HDPE) pipe because it is installed without joint connections and is strong enough to withstand vibrations and pressure from coal trucks and other vehicles that regularly travel the road. The sewer became the first pipeline installed alongside a limited-access Indiana state highway and the longest continuously-pumped force main in the state.
The pipe specified was Phillips Driscopipe|R~ 1000 HDPE pipe (Phillips Driscopipe, Inc., a subsidiary of Phillips Petroleum Company, Richardson, Texas). The Indiana State Department of Transportation was initially worried that leakage at joints, due to corrosion or vibration, could cause damage to the highway, making it dangerous to travelers. However, because its sections are heat fused, the HDPE pipe does not have joints; leakage is prevented and the threat of a road "washout" is eliminated.
Installing the planned 2,500 ft of pipe per day along the roadway required one trenching machine with a single operator, which reduced the costs of the project. Once the trencher had dug a ditch 4 ft deep, it laid 4 in. of stone, then the pipe. Metallic tape was placed over the pipe, to aid in locating the pipe if the road or pipeline need future maintenance.
Eight-in. pipe was used, supplied in 50-ft sections, for the force main. Six-in. connection lines and stub-outs were installed for future connection to development areas. Route 37 remained open throughout the 4 1/2-month project, helping to further reduce worker numbers and costs. Using the smooth-walled HDPE pipe lessened the amount of pumping necessary due to less friction in the pipe, helping to criminate 7 of 12 planned pump stations and saving $50,000 installation costs and $5,000 annual operating costs per station.
The HDPE pipe was also specified because as friction in the smooth-walled pipe is decreased, so is the time the effluent spends in the pipe. This prevents the material from becoming septic and decomposing, avoiding extensive odor generation that must be treated at the pump stations.
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|Title Annotation:||sewer main construction in Indiana|
|Date:||Dec 1, 1992|
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