After two big wastewater spills Tuesday, officials are monitoring tidal water bacteria levels west of the Ashley in the Wappoo Cut and east of the Cooper in three creeks and a pond near the Isle of Palms Connector.
Preliminary test results show that 500,000 gallons of wastewater that flowed from a broken pipe on Rifle Range Road has been contained in ponds at Seaside Farms.
“I can’t tell you what the test results are going to be in the next two to three days,” said Clay Duffie, Mount Pleasant Waterworks general manager.
Three Seaside Farms ponds are interconnected. The third pond is tidal, and tests there have not indicated a problem with wastewater release into the marsh, he said.
Water samples were taken Thursday of nearby Hamlin, Inlet and Swinton creeks. Test results take 18 hours, he said.
Meanwhile, officials will be monitoring fecal coliform bacteria levels after 24,000 gallons of wastewater overflowed Tuesday in the Byrnes Down neighborhood, said Jenny Hagen, spokeswoman for the Charleston Water System.
Heavy rains on Tuesday caused the wastewater system to back up at Lyttleton and Nicholson streets. “Rainwater can find its way into sewer pipes lots of different ways,” she said.
Equipment was dispatched to contain the spill, she said, but wastewater overflowed into the storm drain which discharges into Wappoo Cut connecting the Ashley and Stono rivers.
Signs at Seaside Farms on Thursday advised homeowners and visitors to avoid contact with pond water. Ponds there drain into tidal creeks that feed into shellfish grounds, officials said.
The Rifle Range Road spill occurred when a main pipe carrying wastewater sprang a leak, resulting in a small geyser of sewage in the road. The rains, in addition to corrosion, are cited as reasons for the failure of the 25-year-old wastewater pipe.
About 100 feet of metal “force main” pipe failed. Large holes could be seen Wednesday in a section of the 20-inch pipe as it was being removed. A report filed with state health officials said the pipe failure was caused by a combination of corrosion and increased pumping pressure due to extremely heavy rains.
Repairs to the ruptured Rifle Range Road pipe were completed Thursday. Rifle Range Road from Isle of Palms Connector to Franke Drive was reopened. Seaside Farms-area residents and businesses were advised to not use drainage pond water for irrigation until it is determined to be safe. Residents have been advised to avoid all pond and surface water.
Residents of Seaside Farms to Porcher Bluff Road were told Thursday they could resume normal use of the wastewater system. About 10 subdivisions were affected.
Crews worked around the clock to replace the failed 20-inch steel pipe with a more durable PVC pipe. Hydrogen sulfide tends to corrode metal pipes over time and causes failures such as the one that happened Tuesday, officials said.
As officials monitor the water-quality situation, Dave Belanger said he was ordered to stop commercial harvesting of clams behind Dewees Island and at Capers Inlet on Thursday because of poor water quality that he thinks is related to the 500,000 gallon sewage spill.
Belanger, who has a 25-acre mariculture operation growing clams and oysters, said recent heavy rains that typically wash pollution into tidal waters could have played a role in the water-quality problems.
A state official contacted Belanger by phone to tell him to stop harvesting clams for at least a week because of the water-quality issue, he said.
The state Department of Health and Environmental Control initially confirmed Thursday morning that there was a shellfish-harvesting closure in the area, but further information on the extent of the closure, the location, the cause and how long it would last was unavailable.
In a week, Belanger’s business typically harvests and ships 15,000 clams to restaurants around the country. Each clam brings 40 cents on the retail market, he said. He said another commercial clammer who works at Breach Inlet was ordered to halt harvesting. He could not be contacted for confirmation.