The company doing work on a Rehoboth Beach outfall pipe that will dump treated wastewater into the Atlantic Ocean claims to have encountered a problem while drilling a hole underneath the seafloor.
According to engineering firm GHD, which is managing the project, Manson Construction drilled a hole 3,800 feet below the seafloor to safely install pipe.
Manson tried to put steel casing in the hole, but claims it hit cobble about 700 feet in. The casing got stuck and they abandoned it to drill a hole 10 feet south.
GHD principal and Rehoboth outfall project manager Kelvin George says the issue is pending. Manson already drilled a second hole and is more than 1,100 feet into installing casing - past the point where the previous casing got stuck.
“They have decided to weld the joints now, in the event that they hit something hard again in this new hole, that there would be a little bit more resiliency to the steel casing,” George said.
GHD had hired geotechs to take several samples along the seafloor at various locations that would’ve indicated cobble or other obstacles. The samples they took at the time did not indicate cobble.
“Does that mean that cobble doesn’t exist or couldn’t exist? No. It’s really a function of the way the samples are taken,” George said. “You’re not going to be able to take a sample every 10 feet along a 6,000 foot land section for that matter. It becomes too costly.”
George says construction has been set back and Manson is waiting for good weather, but they still anticipate completing the ocean work by the permit deadlines - March 31.
Manson Construction could not be reached for comment.
Krys Johnson, a spokeswoman for the City, says work has begun on a 24 inch force main that will help treated wastewater travel to the ocean outfall.
A-Del Construction of Newark is handling that portion of the project.