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Pawleys Creek: Tests find no hazard in oil seepage
By Charles Swenson
Tests of groundwater along the North Causeway confirmed the presence of petroleum products, but not in amounts that are hazardous to the public, according to state investigators.
The state Department of Health and Environmental Control is continuing to review test data, said Thom Berry, the agency’s media director and one of nine staff members who took groundwater samples in October.
“We’re not walking away from it,” Berry said.
The investigation began in September after Pawleys Island Mayor Bill Otis reported smelling diesel fumes from dark brown stormwater flowing into Pawleys Creek at the outfall of a drainage system installed by Georgetown County earlier in the year.
DHEC and the Coast Guard checked the outfall, but could not confirm it contained petroleum products.
The stormwater flows from the Highway 17 intersection in concrete pipes. A series of drains and catch basins along the North Causeway collect additional runoff. The DHEC team that returned in late October traced the odor with an “organic vapor analyzer” and found the heaviest concentration at the corner of Pawleys Creekside Loop.
In the late 1980s, DHEC received a report of leaks in underground fuel storage tanks at Marlowe’s store on Highway 17, now the site of Frank’s Restaurant. DHEC staff believe that some of that fuel was still in the groundwater and flowed to the corner of Pawleys Creekside Loop because it is a low spot.
The latest tests were done on a sample of groundwater taken 9 feet below the edge of the North Causeway between Pawleys Island Realty and Pawleys Island Supplies.
DHEC is in “the early stages” of reviewing data from those tests, Berry said.
“So far, we have not found anything that would surprise us,” he said. “Yes, there are some residual levels of petroleum-related compounds, which we would expect to find even after a number of years.”
Linwood Altman, an owner of Pawleys Island Realty and the property on the southeast corner of Highway 17 and the North Causeway, said the smell has been around for years. DHEC drilled monitoring wells on his property in 2000 as part of a cleanup of the leaking tanks from Marlowe’s store.
The cleanup involved injecting air into the groundwater to speed up the breakdown of the contaminants. The project tracked amounts of benzene, tolulene, ethylbenzene and xylenes, known collectively as BTEX, along with methyl tert-butyl ether and naphthalenes, all hazardous compounds present in fuel.
DHEC reports show that the amount of dissolved petroleum products had decreased even before the air injections began. However, the levels increased after that and, in 2002, a “bio-nutrient” was injected into the groundwater to help break down the petroleum compounds.
Concentrations of chemicals in the groundwater shifted under the area between the restaurant and the real estate office, according to DHEC maps.
By 2004, when the remediation project ended, DHEC reported that the contamination in the groundwater “does not present a significant threat to human health or the environment.”
But it said the groundwater should not be used for drinking water or for irrigation.
And DHEC noted that any excavation in the area “may encounter petroleum-impacted soil.”
Staff that investigated the odor complaints said construction of the drainage system may have allowed groundwater containing the petroleum compounds to collect in the gravel that supports the pipes. Heavy rains this summer raised the groundwater level, and the odor is still present after a rainfall.
“There’s probably a little residual breakdown,” Berry said. “You’d expect to see this.”
Since the level of contaminants is not high enough to pose a threat, DHEC will continue to monitor the situation but won’t try to confirm the source.
“Everything they’ve tested is below the levels where it’s unfit for human consumption,” Otis said. “They’ve apparently done as much investigating as we could ask them to do.”
Although he was pleased with DHEC’s investigation, the town still has concerns about the drainage project.
The county installed filters known as “Smart Sponges” in the catch basins, but the filters were missing from some of the drains when DHEC staff opened them to trace the odor. The county also acknowledged that one basin was installed too high for the filter to work.
Town Council last week asked Otis to find out how the county plans to fix and maintain the system. There used to be a ditch along the south side of the road. It was replaced with concrete pipe.
“There’s no filtration that the ditch would provide,” Otis said.