NEW HANOVER COUNTY — At the end of every day at the New Hanover County Landfill, workers are required to cover any new trash at the site with 6 inches of soil. As one could imagine, that ends up being a lot of soil and with a finite amount of dirt on the site the county can mine, it often is looking for ways to supplement its own supply.
With the construction of the North Waterfront Park, the City of Wilmington was hoping to become that supplier and in turn, save some money in disposal fees. But as it turns out, the county is not able to use the soil from the park due to excess volatile organic compounds and heavy metals found in soil samples.
According to the New Hanover County Board of Commissioners’ upcoming agenda, the Environmental Management Department received a request to waive fees for the city to dispose of up to 500-cubic-yards of soil from the North Waterfront Park site. The request itself would cost the county $24,000 if it were approved.
But according to the Director of Environmental Management Joe Suleyman, the county would have been happy to accept the waiver of fees in exchange for the soil but the contamination makes the soil unusable.
“When we get a line on some soil people are trying to get rid of we are going to jump at that opportunity because we have a finite amount of soil we can mine,” he said. “Had it been clean we would have accepted it.”
It might seem confusing — a landfill worried about the cleanliness of dirt — but there is a reason for the county’s pickiness.
Anyone who has seen the landfill knows it is essentially a giant mound, a pyramid shape with a flat top. If the contaminated soil were used just in the center of the landfill, there would be no concerns, Suleyman said. That’s because any rainwater that permeated through the soil would be collected by the landfill’s own collection system, but if the soil was placed on the outside of the landfill runoff could trickle into the stormwater collection system, and that could be a problem.
“If it is inside the landfill there are no environmental issues if we put the soil on the outside of the pyramid any rain will become runoff and end up in our stormwater collection system. We have to monitor our stormwater quality so we can get violations from the state for exceeding those numbers,” he said.
For those wondering about putting a park on top of contaminated land, the project itself took this into consideration and remediation of the land is part of the plan, Suleyman said.
The downtown area of Wilmington has changed over the years from what it is today. From shipbuilding during WWII to other industrial purposes along with dredgings that dumped soil along the banks, the Cape Fear Riverfront was not always a tourist attraction. The majority of the contaminants are leftover from the decades past.
So what exactly was found in the soil samples? Well, the entire report was about 150 pages, so Suleyman helped summarize some of the main contaminants and the amounts.
The first group is RCRA metals, next, he lists aromatic hydrocarbons and organic compounds.
“The Resource Recovery and Conservation Act (RCRA) lists and monitors a group of eight heavy metals which are commonly referred to as the RCRA 8. The reason being, each of these eight metals is extremely toxic at even small concentrations,” according to Hazardous Waste Experts, a waste management service provider.
In the soils from the North Waterfront Park project, arsenic, chromium, lead, and barium were all present.
RCRA METALS:
- Arsenic, 6.3 mg/Kg
- Chromium, 24 mg/Kg
- Lead, 34 mg/Kg
- Barium, 26 mg/Kg
AROMATIC HYDROCARBONS:
- sec-Butylbenzene, 2.1 mg/Kg
- isopropylbenzene (Cumine), 1.2 mg/Kg
- acenaphthene, 1.4 mg/Kg
- fluorene, 2.5 mg/Kg
- flouranthene, 1.8 mg/Kg
- phenanthrene, 4.1 mg/Kg
- pyrene, 1.8 mg/Kg
ORGANIC COMPOUNDS:
- 1-methylnaphthalene, 10 mg/Kg
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