Rehoboth ocean outfall work on schedule

Work on Rehoboth Beach’s ocean outfall is on a tight schedule that may become even tighter based on permits from the U.S. Army Corps of Engineers.

Thanks to a long run of good weather, Seattle-based Manson Construction, the firm handling the installation of the outfall pipe, has already completed about 40 percent of the work, but the firm may need to move even faster to meet environmental deadlines.

“They’re moving quickly, but there’s lots to be done,” said Kelvin George, project manager for city engineers GHD.

Sam Jung, GHD’s on-site engineer, said Manson has already dredged the trench on the ocean floor where the outfall pipe will be placed. He said about one-third of the pipe has already been fused together at a site near Roosevelt Inlet.

“This is really good progress,” George said. “It’s looking good so far.”

Jung said the pipe will be floated out to the trench in sections. Weights will be attached to each section of pipe as it is sunk into the trench. Once the pieces are in the trench, divers will fuse the sections together, Jung said.

How long Manson will have to finish the work is an open question. George said Manson based its bid around a permit granted by Delaware Department of Natural Resources and Environmental Control, stating that work in the ocean must be completed by March 15. But after the contract was awarded, the U.S. Army Corps of Engineers granted permits that state Manson must be finished by Feb. 28.

“Two weeks is a lot of time,” George said. “With good weather, you can get a lot done in two weeks.”

George said GHD is trying to get an extension from the regulatory agencies to ensure that Manson can complete the job. The contractor is working from 6 a.m. to 6 p.m., six days a week, and has also requested to work on Sundays to meet its deadline.

Meanwhile, George said the first two change orders from Manson have saved the city nearly $2 million. The first change order was for $1.34 million for changes to the construction method, including using concrete mattresses instead of stone to cover the trench once the pipe is installed. Jung said using stone was in GHD’s original specifications, but when Manson came on board, the contractor recommended concrete mattresses as a cheaper alternative that would also save time.

Jung said the mattresses will lie flat on the ocean floor and then be covered with sand to restore the bottom.

Using concrete mattresses requires a trench that is shallower and less wide than originally planned, saving the city $100,000.

The second change order is a $600,000 modification to a diffuser that will disperse treated effluent into the ocean. These two credits brought down Manson’s contract from $27 million to $25 million.

George said contractor Allan Myers has just mobilized for work on the effluent pump station and upgrades to the city’s wastewater treatment plant. The pump station will be built on-site at the plant and will pump the treated effluent through the force main. The plant upgrades include new clarifiers and screening equipment. George said Allan Myers’ equipment should all be on-site in early December.

“That work is off to a little bit of a slow start but we should be able to catch up with that,” George said, explaining that the delays were caused by changes to the pump station design.

The final element to the project is construction of the force main pipe to take treated effluent from the plant to the outfall pipe. George said contractor A-Del Construction has nearly completed work on Roosevelt Street, with 1,600 linear feet installed.

Jung said construction should reach State Road in two to three weeks. He said construction will not reach Rehoboth Avenue - where the pipe will be drilled under the road and under Grove Park out to Henlopen Avenue - until the begininng of next year.

George said in two to three weeks, a second A-Del crew will begin installing pipe, starting near Deauville Beach. The two crews will work toward each other, possibly meeting near Grove Park. George said it will take three or more weeks for the second crew to get to Henlopen Avenue, but residents will be notified when force main construction could impact them.

“The plan is to have the contractor, as well as GHD, knocking on doors at least a week ahead of time,” he said.

Boats warned to stay clear of outfall area

City officials are urging recreational and commercial boaters to use caution when operating their vessels near the area where the outfall construction is taking place.

Manson Construction requests all vessels to remain a quarter-mile away from the crane barge as the mooring system is made up of four anchor lines that extend from the barge to the ocean floor. Rehoboth spokeswoman Krys Johnson said the mooring anchor lines may exceed 2,000 feet beyond the crane to help stabilize the barge’s position.