A study commissioned by the U.S. Army Corps of Engineers (USACE) has identified problems with the groundwater in the vicinity of the Pearce Creek Confined Disposal Facility, a site the Corps seeks to utilize for maintenance dredge sediment from the Chesapeake and Delaware Canal southern approach channels.
The U.S. Geological Survey (USGS), which collected field data over a period of two years, found problems with the taste and odor of water samples taken from the disposal facility and the surrounding area and, more significantly, the presence of several elements, including beryllium and arsenic, in amounts that exceed the federal Environmental Protection Agency's health advisory levels.
The commander of the USACE Philadelphia District, which operates the canal, thanked the USGS for its work and welcomed the report as the next stage in identifying what can be done to bring area residents safer and more palatable water and what steps are necessary before the Pearce Creek facility can be safely reopened.
"We have a better idea now of what the problems are, which is why we commissioned the study in the first place," said Lt. Col. John C. Becking. “Now we can move ahead, and, working with the residents, the Maryland Port Administration and the Maryland Department of the Environment, work out solutions that will address the water issues and allow us to reopen this important disposal site."
The Corps is exploring with its partners the possibility of new wells for residents and is working on the construction of a barrier within the disposal site to preclude any additional influence on the local groundwater.
The USGS took samples from 50 wells --- 35 of them within the disposal area, and 15 in nearby residential areas. It found that nearly all the samples had problems with water, taste or color --- what the Environmental Protection Agency calls "secondary" water problems.
More seriously, it discovered that 71 percent of the samples had a problem with manganese, nickel, sodium, sulfate, strontium or zinc. The samples contained one or more of these elements in amounts that exceed the EPA's heath advisory levels.
Furthermore, 15 percent of the samples exceeded the EPA's health advisory levels for beryllium; and two percent of the samples exceeded the levels for arsenic, cadmium or thallium.
These maximum contaminant levels are enforceable for public water supplies but not for private wells. Well owners can and do install filters and other commercially available treatment systems that are able to remove the aforementioned elements and restore water quality to acceptable levels.
The Chesapeake and Delaware Canal connects the Delaware River with the Chesapeake Bay and enables ships to cut close to 300 miles off the trip from Philadelphia to Baltimore. Keeping it and its approaches free of shoaling and clear to a depth of 35 feet requires periodic dredging.
The Pearce Creek site was used for the placement of dredge material from the C&D canal southern approach channels from 1937 to 1992. After 1992 the Pooles Island open-water placement site was used until it was closed in 2010 in accordance with Maryland State law. With the closing of the Pooles Island site, USACE looked to re-use Pearce Creek and commissioned the USGS to study the impact of the site on groundwater.
Engineers and geologists from the USACE, utilizing the USGS report and carrying out their own research and design, have developed a plan to deal with the groundwater situation within the disposal site. It calls for the construction of an impermeable barrier within the disposal site that would effectively seal its contents off from the residential areas.
Before the Corps can reopen Peace Creek the Maryland Department of the Environment must evaluate the environmental integrity of the USACE’s plans for the use of the site and grant permission, issuing what is called a "Water Quality Certificate."
The USGS studies identified problems with water samples taken from two relatively shallow aquifers underlying the disposal site and residential areas. But it found no problem with a deeper aquifer, about 200 feet beneath the surface, into which the new wells could be sunk.
Tim Kelly, the Army Corps' project manager for the C&D Canal, expressed hope that the issues will be resolved. Kelly said that the only long- term alternative to Pearce Creek is Poplar Island, an artificial island in the Chesapeake Bay, but that the increased cost of transporting the dredge material is significant and Poplar Island is already needed to handle dredge material from the southern access channels to the Port of Baltimore.
The report Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area and Vicinity, Cecil County, Maryland, 2010-2011 is now available