WorldWide Drilling Resource

36 JULY 2021 WorldWide Drilling Resource ® From Contamination to Remediation Compiled by Editorial Staff, WorldWide Drilling Resource ® One of the largest and most complex groundwater remediation projects in our nation’s history is underway. In New York, Bethpage’s Navy-Grumman Plume is 4.3 miles long, 2.1 miles wide, and as much as 900 feet deep. It sits in an aquifer which is the only drinking water source for the densely populated region. The complex pollution is composed of two dozen contaminants, includ- ing multiple carcinogens. Most significant is the potent metal degreaser trichloroethylene, present in the pretreated water at levels thousands of times above state drinking standards. Eleven public water supply wells are impacted by the groundwater contamination, and 16 public water supply wells are threatened by the south-southeast migration of the groundwater plume. Quite a few expensive treatment systems have already been installed to remove contaminants from public wells within the plume. The New York State Department of Environmental Conservation’s comprehensive plan to contain and treat water from the plume estimates it will take $585 million over the first 30 years alone. Near total eradica- tion of the contamination will not come for 110 years. The state’s published remediation procedures call for full hydraulic containment of the groundwater plume, including the instal- lation of 24 groundwater extraction wells - eight in the interior of the plume and 16 along the margins. In total, the extrac- tion wells will withdraw approximatedly 12,100 gallons per minute (17.5 million gallons per day) of contaminated water from the aquifer. Using air stripping technology, the extracted groundwater will be treated at one of five groundwater treatment plants. Treated water will be used in one of three ways: returned to the aquifer system, reused for irriga- tion purposes, or reused to augment surface water flow in Massapequa Creek. Northrop Grumman’s work plan included drilling profile borings and monitoring wells to support the contain- ment wells in the east-central portion of the plume. The Navy’s work plans included installation of recovery wells at four spots along the leading edge of the plume, as well as two recovery wells in the plume’s interior. Using an existing recovery well in the plume’s interior, they are also designing an interim groundwa- ter extraction system, targeted to be oper- ational by this month. Northrop Grumman is still constructing its first comprehensive off-site system of wells to remove plume contaminants, joining one the Navy oper- ates and another it is planning. Full con- tainment of this groundwater plume will prevent the further spread of contamina- tion to water supplies in neighboring communities and provide peace of mind to local residents. Drill rig used for vertical profile boring. Photos courtesy of New York Department of Environmental Conservation. ENV Fast track drilling of a groundwater extraction well.