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FOR IMMEDIATE RELEASE
WORK CONTINUES ON RUPTURED WASTEWATER LINE AT SAND ISLAND
The City continued its efforts today (March 8, 2004) to access a large, pressurized sewer main that ruptured Thursday, causing a wastewater spill estimated at two million gallons.
Two exploratory excavations were used to locate the force main and its alignment coming up from beneath the Honolulu Harbor entrance channel. Interlocking steel sheet piles 30 and 50 feet in length and approximately four-feet wide were installed on either side of the ruptured pipe to hold back the surrounding soil and to help hold back the groundwater, which exists about five feet below ground surface. The sheet piles extend about 40 feet on either side of the location where the water from the force main was coming up through the ground in the State Park.
Late Sunday, it was decided to use a process called “jet grouting,” which will provide a leak-resistant system that will significantly reduce the amount of groundwater that would have to be pumped out of the excavation site. The jet grout drill rig and its supporting equipment, including a tall bulk cement hopper, are being brought onto the site this afternoon. Once treated with jet grout, the soil will sufficiently cure after five to seven days, holding back the groundwater so the pipe can be exposed and the problem in the pipe can be determined. Possible causes for the break include corrosion, material stress failure, structural damage due to settlement of the pipe, or a combination of these factors.
The City has assembled a team of consultants to review the possible causes of the problem and to start identifying potential fixes that will be strong and durable enough to last many more years. This will take place while the jet grout cures. This will cut down the time of the actual pipe repair, and is aimed at getting the force main back into operation as soon as possible.
For more information, contact City Environmental Services Director Frank Doyle at
|Monday, March 08, 2004|