Rehoboth’s public works director says stormwater is polluting the ocean off Rehoboth Avenue in part because a critical pumping system has not worked in up to two years.
Two months ago, a study showed that after big storms, Rehoboth’s aging stormwater infrastructure is sending rainwater with high levels of biocontaminants into the ocean.
Public Works Director Kevin Williams, who has been on the job since June, said he still doesn’t know all the sources of pollution, but they have figured out at least one problem – the pumping system for the Rehoboth Avenue draining vault isn’t working.
During a commissioners workshop July 9, Williams said the system is designed to pump the first inch of stormwater, which contains most of the liquid contaminants and small trash items washed into the system, to the wastewater plant for treatment. He said he was told the system hasn’t worked in up to two years.
Instead of pumping that water away, it remains in the vault area, becoming a breeding area for contaminants. During a big storm, the vault fills and flushes into the ocean, Williams said.
In May, international engineering firm GHD reviewed with commissioners the results of a $250,000 state-mandated study into the city’s stormwater system. The study’s data showed in the six hours immediately following six major storms during the study period, ocean water near the city’s five stormwater outfalls from Grenoble Place south to Delaware Avenue averaged nearly 2,000 colony-forming units of enterococcus per 100 milliliters. The recommended level of colony-forming units is zero to 60.
The Department of Natural Resources and Environmental Control issues swimming advisories when enterococcus levels are greater than 104 colony-forming units per 100 milliliters. Enterococcus is found in the gut of all warm-blooded animals.
As part of the study, GHD provided a water-flow model showing that keeping the ocean waters near the shoreline below 60 units all the time would require extending four of the five stormwater outfalls 1,200 feet, at an estimated cost of $15 million. Less-effective remedies also included 175,000 square feet of permeable pavement on Rehoboth Avenue at $2 million, engineered sand filters at $740,000, and flushing 36,000 linear feet of pipe at $144,000.
During the recent workshop, Williams said, the Rehoboth Avenue pumping system, installed when John Hughes was mayor during the 1980s, would be fixed after an evaluation to see if specific parts or the whole system should be replaced.
In addition, Williams said the drainage vault of Rehoboth Avenue and the sand filter for Wilmington Avenue would be cleaned frequently. He said they’ve been getting cleaned once a year, but that would change to at least once every 60 days.
At the time of the workshop, Williams said the reason the pump wasn’t working has not been determined, but he said he would know by the July 20 commissioners meeting.
Williams said before he recommends anything in the way of stormwater outfall extensions, the system should be inventoried, and a public outreach campaign should occur.
Williams also said it was going to be important to reach out to the businesses along Rehoboth, Baltimore and Wilmington avenues to remind them of the proper disposal methods.
Commissioner Jay Lagree said it was important to remember there were no water samples actually taken out in the ocean for the study. He strongly encouraged Williams to get out into the water to take real-time water samples.
Following the meeting, Krys Johnson, Rehoboth spokeswoman, said the city became aware of problems with the Rehoboth Avenue stormwater pump when GHD was sampling the stormwater infrastructure. She said the vault was cleaned out in the spring, but the pumps were not repaired because the city was waiting for the final stormwater report.