Rehoboth approves outfall route

The Rehoboth Beach commissioners have made it official: the route of the city’s ocean outfall pipe will run along Henlopen Avenue before ending 6,000 feet off Deauville Beach.

City officials and engineers have long said the proposed route – from the wastewater treatment plant off State Road along the banks of the Lewes-Rehoboth Canal under Grove Park and then down Henlopen Avenue – is the most practical and cost-efficient way of pumping treated effluent to the ocean.

In a presentation to the city commissioners Jan. 20, engineers Lee Mayers and Rip Copithorn of GHD said an alternative route going along State Road and then under the Rehoboth Avenue/Fifth Street intersection and down Columbia Avenue was considered, but dismissed.

Mayers cited reasons ranging from the numerous underground utilities that would have to be avoided, the narrow right-of-way along Columbia and a potentially negative impact on businesses when construction crossed Rehoboth Avenue.

The advantages of the Henlopen Avenue route, Mayers said, are fewer utility lines, a wider street and no commercial areas along the route.

The outfall pipe will be built largely using open-trench cutting, but horizontal directional drilling will also be used.

Directional drilling can go deeper into the ground than open trench. Mayers said open cut is cheaper than directional drilling, but the latter is more advantageous when trying to avoid traffic problems or environmental issues, including saving trees. He said open cut will be used whenever possible to keep the project cost-efficient.

Mayers said open-cut construction would be used along Henlopen Avenue and would take a month or two. During this phase, he said, 100 to 200 feet of pipe will be installed per day. He said after each day’s construction, state law mandates the trenches be backfilled and covered with steel plates, to avoid anyone falling in.

Directional drilling will also take one to two months from behind the Park Place condominiums along the canal to the northeast corner of Grove Park.

Mayers said the minimum depth for directional drilling is 10 feet, but most drillers try to stay 10 to 15 feet underground. Open cut is typically only four to five feet deep, he said.

Mayor Sam Cooper said choosing the alignment now was a way to tell the public where the pipe would go and why the Henlopen Avenue route was chosen. He said sometime in mid-March, the city will hold a public hearing on the environmental impact statement on the outfall. Cooper said the statement would be available for public view 30 days before the hearing.

The city was required to prepare the statement as a requirement to secure state and federal funding for the $30 million project through the state’s Clean Water Revolving Fund.