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Engineers detail Rehoboth outfall project

Contractors to mobilize Oct. 1 for massive trenching, drilling operation
September 25, 2017

An army of construction contractors is set to descend on Rehoboth Beach to build the city’s $52.5 million ocean outfall.

To prepare residents for the invasion, the city’s engineers and contractor representatives held a town hall meeting Sept. 16 to lay out the battle plan.

Brandon Gott, engineering project manager for construction managers GHD, said contractors are permitted to work from 7:30 a.m. to 6 p.m., Monday through Thursday. Gott said crews will not work Fridays to accommodate extra beach traffic on good weather days. 

Two top topics of discussion were the force main, which will take treated effluent from the city’s wastewater treatment plant to the ocean outfall staging area at the Deauville Beach parking lot, and the outfall pipe itself, which will be drilled from the beach to a diffuser site 6,000 feet offshore.

Gott said the force main work will start at Roosevelt Street, the main road to the water treatment plant, and then go down State Road to Canal Street. Once contractor A-Del Construction gets to Rehoboth Avenue, Gott said, the construction method will switch from open trench to jack-and-bore. A-Del will dig a pit and then drill a hole underneath Rehoboth Avenue and Grove Park. A second pit will be dug outside Grove Park and the pipe will be threaded through the hole to the second pit. Once A-Del workers have gone past Grove Park, Gott said, they will go back to an open trench cut down Henlopen Avenue to the Deauville Beach parking lot. He said all roads will be repaved and the shoulder along both sides of Henlopen Avenue will be restored with new gravel. 

Jake Yohe, project manager for A-Del Construction, said road closures will occur as the project moves along; closures will be noted on the city website, he said. The open trench will be covered with steel plates at night, and signs will direct drivers and others around the work site. Yohe said there is no specific timetable for closing sections of the roadway because crews may discover various problems underground that could slow work. Gott said A-Del will likely average about 50 to 80 feet per day.

In addition to the force main, City Manager Sharon Lynn said the city would also install a new water main along Henlopen Avenue. Lynn said the water main in place now has been there since the 1940s. Mitch Seitz, regional manager for A-Del Construction, said work on the water main would likely begin in November. The crew constructing the force main would still be working on the south end of town, so Seitz said a second crew would be brought in to install the water main and have it close to finished before force main construction gets to Henlopen Avenue. 

Regarding the jack-and-bore process under Grove Park, Yohe said it would take about two months to bore about 360 feet of pipe. Gott said Canal Street would be closed at Rehoboth Avenue, but drivers will have access to Canal Street from State Road. Rick Kirchhoff, owner of the Canalside Inn on Canal Street, asked city officials to have good signage on the road in that area; Kirchhoff’s business is right near the pathway of the force main. Mayor Paul Kuhns said he and members of the public works department would meet with Kirchhoff when construction got closer to figure out the most appropriate places for signs.

All told, Gott said the force main pipe trench would be 5 to 6 feet wide and 4 to 20 feet deep, depending on what section A-Del is working on. 

Gott said the Deauville Beach parking lot will be the main staging area for the outfall pipe installation. The public will have access to Deauville Beach and the nearby tennis courts, but there will be no parking, as the staging area will be fenced off for safety reasons, Gott said. A pit will be dug to install a drill that will bore down to the ocean floor. GHD project manager Kelvin George said the pipe will go as far as 80 feet down under the sea floor and then come back up at the end, where a diffuser will be attached to disperse treated effluent.

Contractor Manson Construction will have a barge in the ocean at the end of the pipe, where the diffuser will be located.   Gott said the timeline for the ocean work is limited by environmental regulations from Oct. 15 until March 1. 

“They’re working straight through unless weather impacts,” he said.

 

 

 

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