The operators of the Millersville Landfill have rejected recommendations that the county dig up and move 250,000 cubic yards of trash to prevent further ground water contamination.
GeoSyntec Inc., an Atlanta-based consultant, said the county should consider consolidating four of the landfill's five oldest disposal areas, which were abandoned nearly a decade ago. After they are combined, the three remaining mounds should be covered with an impermeable cover that prevents rain from seeping through the trash, carrying pollutants into the water below, the consultant said.
The consultant recommended that the county combine cells 1 West and 1 East, as well as cells 3 and 4. It would consolidate about 54 acres of trash into 36 acres, making construction of environmental safeguards easier, GeoSyntec said.
Those safeguards, which would include a carbon-filter system to cleanse contaminated water, could cost as much as $6.5 million and require about one year to install, GeoSyntec said.
Utilities Director Thomas H. Neel said yesterday that the county will not dig up any trash unless ordered to by the state.
"We're not going to mine those [mounds]," said Neel, whose department manages the county's solid waste, sewerage and water facilities. "You can't just open them up and mine them in one day. By disturbing them, you open up the chance of additional problems."
GeoSyntec's recommendation follows a May 29 report by another county consultant who said the county should not excavate cells 5, 6 and 7 -- dubbed "Mount Trashmore" by Neel and neighboring residents -- because it would pose grave health risks.
The county has combined cells 5, 6 and 7 into a single, 225-foot-high mound. The Maryland Department of the Environment asked the county to consider lowering the height by 48 feet to comply with state law.
GBB, a Falls Church, Va., consultant, said excavating those cells -- including an estimated 3,080,000 cubic yards of trash and dirt -- could cost $155 million and take at least four years. Exposing the trash, especially to rain, would increase the risk of ground water contamination and generate severe odors, GBB said.
GeoSyntec acknowledges "potential adverse impacts" of combining the older cells, but said the problems can be mitigated because of the "relatively small quantities of waste" involved.
The MDE is reviewing the recommendations of both consultants and the county. The county hired both GeoSyntec and GBB three years ago to help redesign the 567-acre landfill and secure a new operating permit.
"The problem is, the [GeoSyntec] report doesn't say enough," Neel said. "GBB did a good job of delineating the problems with mining trash. Although they are good at designing landfills, GeoSyntec really doesn't have any experience at mining sites."
Neel said GeoSyntec believed that relocating some of the trash would free up space for a yard waste composting facility. But, Neel said, that could create additional problems with neighboring residents who say the county has broken promises it made when Millersville opened 18 years ago.
Neel said he would like to keep a county pledge to convert those areas into parkland.
"I want it to be a recreational site, and I've been told it can be done," he said. Specific park proposals will be made public by this fall, he said.
Toxic chemicals associated with household and industrial degreasers have been found in the ground water near cell 4 since 1985. Similar pollutants also have been found in the water near cell five since 1990.
GeoSyntec says the contamination has not moved much beyond the vicinity of those cells.
"The apparent sources of the contamination are unlined cells 4 and 5," it says.
In April, the county discovered four tainted residential wells near cells 1 East and West. However, GeoSyntec said evidence is inconclusive if those pollutants also came from the landfill.
Whether or not the cells are combined, the GeoSyntec study recommends that the county cap the abandoned disposal areas with an impermeable cover to prevent further contamination. The report also suggests the county dig ground-water recovery wells along the northern edge of cells 1 through 4. The collected water would be cleansed at a "carbon absorption ground water treatment system" and then released back into the ground.
In an alternative plan, the county could construct a "slurry wall" -- a 30-foot deep trench filled with porous clay and water -- to keep water contaminated by the trash from flowing away from the site. The captured water would be pumped and treated as before.
Under both options, the consultant recommends the county dig 10 additional ground water monitoring wells.
The first option, "Alternative G," would cost about $6 million initially and $200,000 annually to operate, the study said. The second, "Alternative H," would cost $6.5 million initially, and about $200,000 for annual expenses.
Other options considered included replacement of about 50 residential wells, which lie in the same ground water zone as the waste in cells 1 through 7 and, therefore, are more likely to be contaminated.