Garden City and Hempstead residents questioned state officials who they say failed to alert them of a former utility gas plant site in Hempstead that has apparently produced a gigantic groundwater plume through the residential area.
KeySpan, owners of the site, along with New York State Department of Environmental Conservation (NYSDEC) officials, attempted to ease residents' concerns of possible vapor intrusion and water contamination during a meeting June 28 at Adelphi.
The Hempstead Intersection Street former manufactured gas plant site in Garden City/Hempstead.
According to Karen Young, a KeySpan representative, the former Hempstead Intersection Street manufactured gas plant (MGP) spawned a groundwater plume that is flowing generally south from the site and is approximately 600 feet wide and extends for about 3,800 feet. It starts at a depth of between approximately 24 feet and 30 feet beneath the ground surface -this depth provides some buffer between the ground surface and the surface of the groundwater, Young added.
Investigations and exposure assessments have indicated there are "no open pathways between the potentially harmful materials associated with the site and the people who live and work nearby. Any risk of health effects would be directly related to the presence of such open pathways."
Residents were not at ease, however, questioning why they weren't told of the plume and the ongoing efforts to clean it up. According to Young, KeySpan officials met with villages of Garden City and Hempstead and have since kept them informed about the status of the investigations and the site since entering into an Order on Consent with the NYSDEC back in 1999.
Further, approximately 400 property owners received a mailing with information about the site and a questionnaire to gather data to determine whether there were any private wells in the plume path. Only four active groundwater wells were identified as a result of the mailing. These four wells, however, are actually outside of the plume area, Young said, and are not used for drinking water but rather for irrigation or air conditioning.
The area of the site-related groundwater plume is bounded approximately within Second Street to the north, Sealy and Terrace Avenue to the east, Hilton Avenue, Kensington Court and Cathedral Avenue to the west and Front Street to the south.
The final remedial investigation report found the presence of BTEX (benzene, toluene, ethylbenzene and xylene), PAHs (polycyclic aromatic hydrocarbons) and total cyanide, materials typically associated with gas manufacturing, in both soil and groundwater. According to the report, "most of the materials were found either in shallow soils in the upper 8 feet of the site near where the actual MGP operations were located and/or in a zone approximately 24-34 feet below grade both on and off-site."
The investigation also showed non-KeySpan related, off-site sources that are contributing chemicals to the plume path. The NYSDEC is responsible for ensuring that all responsible parties address these non-KeySpan related sources.
Despite these findings, chemical constituents from the site "have not adversely impacted the drinking water supply wells serving the nearby communities and are not expected to adversely affect those wells based on anticipated normal pumping rates," the report stated.
"There is no risk of exposing people to potentially hazardous materials," Young assured, adding that a cleanup could not be initiated on a complex site until the NYSDEC, New York State Department of Health and KeySpan fully understood the environmental conditions that needed to be addressed. Now that those conditions are fully defined, a feasibility study is currently being prepared to present the recommended remedial action plan and an interim remedial measure is planned for the fall.
This next phase of the project will attempt to differentiate the non-KeySpan contaminants to the off-site plume. A supplemental soil vapor investigation is also planned.
Routine water testing is being conducted in accordance with Nassau County Health Department oversight. As a precaution, property owners on the plume path should consult with their village's building department in the event they plan to dig more than 20 feet below the ground surface.
"The site and its underground plume - which is heading away from Garden City - are wholly contained within the Village of Hempstead," Garden City village spokesperson Brad O'Hearn said. "Because the site is adjacent to Garden City water wells on Hilton Avenue, the village retained water consultant H2M Group to investigate. It advised that there is no danger of contamination to village water supplies. The village will continue to monitor its water supplies and the activities of KeySpan and the State Department of Environmental Conservation to assure the safety of village residents."
The 7.5-acre Hempstead Intersection Street former MGP site is primarily located within the Village of Garden City. The site's border between Garden City and Hempstead is located "just within" the site's southern property boundary and only a small portion is located within Hempstead. Residential properties are located north of the site, along Second Street in Garden City.
The MGP began operations in the early 1900s, originally producing coal gas but was later converted to a carbureted water gas process after 1910, according to the NYSDEC. Following the arrival of natural gas, the site served as a "peak/emergency facility to ensure gas supply until all MGP operations ceased in the mid-1950s." Soon after, the plant was demolished.
LILCO acquired the site in the early 1930s. Later, in 1998, when LILCO merged with Brooklyn Union Gas, KeySpan Corporation was formed and became owners of the site. KeySpan entered into a Consent Order with the NYSDEC in 1998 to conduct a remedial investigation, which was completed in accordance with the scope of work presented in the investigation work plan, dated June 2000, and the Phase II investigation work plan, dated June 2001. In 2003, the NYSDEC accepted a remedial investigation report but then required supplemental remedial investigation work (which included more soil and water testing and further evaluation of public water supply wells and a private groundwater well survey), which is included in the final remedial investigation report the NYSDEC approved this year.
The final remedial investigation report, along with other documents regarding the Hempstead Intersection Street site are available for review at the Garden City Public Library (located at 60 Seventh Street) and the Hempstead Public Library (located at 115 Nichols Court). If residents have questions regarding possible vapor intrusion concerns, they are urged to contact Sharon McLelland of the NYSDEC at 631-444-0241.