Suffolk County has joined in an effort to conduct new tests of groundwater wells around a toxic plume in Bay Shore after elevated toxins were found in water pumped from beneath a resident's home last month.
Suffolk said it is testing water from the sump pumps of two residents' homes, and from seven other wells it has drilled in the area.
The work follows the discovery of increased toxin levels at a home that had recently installed a sump pump beneath its basement. As Newsday reported last week, when groundwater levels began to rise in December, the system started pumping -- and odors infiltrated the resident's home and yard. Tests of that water showed elevated levels of naphthalene, a possible human carcinogen, and other toxins from former manufactured-gas plants, said the homeowner, who declined to be identified.
The state Department of Environmental Conservation, which is overseeing the remediation, Monday said it was "directing National Grid to aggressively respond to this new finding of shallow groundwater contamination" in the westernmost plume.
Environmental workers on Friday were at the home adjacent to the one that reported the contamination, drilling a new monitoring well.
At the same time, crews for National Grid, which is responsible for the cleanup, were installing a new gas main line on the same street after residents last week complained of strong gas odors in the neighborhood.
National Grid spokeswoman Wendy Ladd said the gas-main work is "unrelated to the groundwater sampling."
Groundwater samples were taken from wells on Union Boulevard, Lanier Lane and Cooper Lane on Monday.
For neighbors who have been dealing with odors, construction trucks and reports of new contaminants, the news has been unsettling.
"We, in this area, are not as confident in the success of the results," resident Bill Sullivan wrote to the DEC. "In fact, the results as well as the data that has been collected are suspect to the residents. The process that has been used here causes us all great concern."
DEC spokeswoman Lisa King said the agency was working to determine if the discovery of the new toxins was isolated. A map of the cleanup progress distributed by the DEC last fall shows the plume had entirely retreated around the house that reported the toxins.
"We have begun to evaluate whether this new finding is localized and whether it is related to the effects of Hurricane Sandy or some other change in groundwater flow conditions," King wrote in an email. "Based on field observations during DEC's inspection of neighboring properties this past week, the problem appears to be localized; however, laboratory results of samples taken during the inspection are pending."
King said the agency "remains confident" that a separate, larger plume has been "effectively addressed" by the remediation.
In a statement, Grace Kelly-McGovern, spokeswoman for Suffolk County's Department of Health Services, did not explain why the tests were being done, but said Suffolk staffers were invited by state officials "to address homeowner concerns" at the site.
Bay Shore was once the site of a plant that over a century made vaporous gas for heating and cooking before the era of natural gas. The facility, and hundreds like it across the state, left legacies of toxins beneath them.