FOR IMMEDIATE RELEASE
CONTACT: WSSC Communications
(301) 206-8100
communications@wsscwater.com
LAUREL, MD, May 20, 2009:
A forensic investigation of the rupture of a 66-inch water main on River Road in Bethesda last December has traced the failure of the pre-stressed concrete cylinder pipe (PCCP) to improper installation 44 years ago. The main burst early morning on December 23, 2008, in the 8500 block of River Road.
The four-month investigation showed that the pipe manufactured in 1965 was installed directly on rock which led to cracks and corrosion. “The installation contractor failed to remove rock and fill the trench bottom with selected material to provide uniform and continuous bearing support for the pipe in accordance with Washington Suburban Sanitary Commission (WSSC) specifications in force in 1965,” according to a forensic analysis statement by Lewis Engineering and Consulting Inc. of Gainesville, Florida.
Teresa D. Daniell, WSSC Interim General Manager, said: “Though I am satisfied we have a clear finding as to the cause of the water main break, the analysis is by no means the conclusion of WSSC’s investigation. We now have to determine how this could have happened and determine if there are any additional problems similar to this.” WSSC is now retrieving paper records from 1965 when the pipeline was installed. These records are not at WSSC headquarters, but in a storage facility.
“The techniques used today to inspect pipe today versus ten years ago have improved,” said Gary Gumm, WSSC Chief Engineer. “With today’s technology, we should be able to discern this type of breach.”
Laboratory testing of materials removed from the intact portion of the failed pipe did not find “any apparent or confirmed deficiencies in the construction of the pipe” manufactured by the Interpace Corporation, according to the analysis.
After contractors removed the broken pipe, a WSSC inspection showed internal cracks in three additional sections of pipe in close proximity to the failed section. A fifth section of pipe did not have cracks or other visible signs of distress, but it was removed to expedite removal and replacement of the damaged sections.
During FY ’09, WSSC is inspecting 10.8 miles of PCCP 36” and larger and installing acoustic monitoring. About 20 miles of PCCP pipe have been inspected in the last four years. WSSC has approximately 150 miles of PCCP water mains in its system that are 36” and larger.
The complete consultant’s analysis is available on WSSC’s Web site at www.wsscwater.com
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