Public meeting about groundwater contamination near the North Wake Landfill

If you were to excavate the trash of the late 1980s and early 1990s, you might find cracked Rubik’s Cubes and soiled Pampers, broken televisions and half-empty paint cans, crushed nozzles of roach foggers and bottles of weed killer.

Beginning in 1986, for more than 10 years, Wake County residents tossed their garbagesome innocuous, some hazardousin bins that sanitation workers then hauled to the North Wake Landfill, which, when it closed in 1997, held 1.4 million tons of trash.

That particular 44-acre landfilllater there were three on the site near Durant Road, north of I-540was unlined, as the construction of lined landfills wasn’t required by the state until 1998. So the lead in the TV tubes, the cypermethrin in the pesticides, the vinyl chloride in paint and the 2,4-D in the herbicides could leak and over the years worm its way into the fractured bedrock and eventually into the groundwater, which can move several yards or, depending on the geology, several miles.

“It’s unfortunate, but not uncommon,” said Tommy Esqueda, Wake County director of environmental services. “Now we have programs for electronics, paint, herbicides and pesticides so they don’t go in the landfill, but not then.”

Wake County and state environmental officialsand citizens themselvesare paying the wages of previous environmental sins. Several years ago, low levels of contaminationalthough higher than the state’s allowable levels for groundwaterwere detected in monitoring wells near the old landfill.

State and local environmental officials say the contamination, which, according to county documents, includes lead, mercury, beryllium, cadmium, herbicides and pesticides, hasn’t reached a nearby creek. Nor does it threaten drinking water, they say, because nearby residents are on city water and not well. Nonetheless, the cleanup could cost upward of $800,000 and take as long as 30 years.

County officials are hosting a public meeting Friday to tell residents about the contamination, explain the cleanup options and receive feedback about the plan. After the meeting, county staff will choose a cleanup option, which must be approved by the N.C. Department of Environment and Natural Resources (N.C. DENR).

State and county officials are recommending using monitored natural attenuation (MNA) and air sparging to reduce the amount of contamination in the groundwater. Under MNA, monitoring wells will be sampled semiannually to detect any change in the amount or type of contamination, as well as its path. Air sparging, explains Esqueda, injects air into the groundwater system. Oxygen creates an environment that helps break down the materials.

According to Wake County documents, capital costs for the two methods combined is an estimated $436,000. Operating and maintenance costs are projected at $426,000 over 30 years, not accounting for inflation.

The cleanup won’t affect Wake County and Raleigh’s plan to convert part of the 116-acre landfill site, primarily the buffer area, into parkland, including walking trails. The unlined landfill is fenced and locked, and no portion of the park will be in that area, county officials said.

Most of the state’s 128 unlined landfills leak, said Ed Mussler, permitting branch supervisor for the solid waste section of the N.C. Department of Environment and Natural Resources’ Division of Waste Management. About half of those landfills remain open.

A more immediate threat occurred at the unlined landfill in December 2007, when higher than allowable concentrations of potentially explosive methane gas was detected in gas monitoring wells. An explosion could devastate nearby subdivisions and schools. Subsequently, the county installed a ring of gas extraction wells that decreased the methane concentrations and routed the gas next door to pharmaceutical company Tyco, which uses it to supplement natural gas in operating its boilers.

Shortly before the unlined landfill closed, Wake County opened a 70-acre lined landfill on the same land. It contained 4.85 million tons of trash when it closed in 2008. A five-acre landfill for construction and demolition debris, the smallest of the three, operated from 2000 to 2003 and held 120,000 tons.

Wake County trash now is hauled to the South Wake Landfill near Holly Springs.