As of August 2010, National Grid has competed about 80% of the installation work for oxygen delivery system #2, located from Mirschel Park to Kensington Court. The oxygenation system will treat the groundwater plume associated with the Hempstead former Manufactured Gas Plant (MGP) Site by accelerating the rate of natural bioremediation within the groundwater plume. National Grid has completed the installation of the wells and oxygen lines in Mirschel Park, on private property at 158 Hilton Avenue, along the right-of-way on the east side of Hilton Avenue, and on the south side of Kensington Court.  Please see the attached figure showing the location of the treatment systems. 

Remaining work planned for system #2 during August and September 2010 includes completion of the installation of new groundwater monitoring wells, testing the performance of the oxygen injection wells, and continuing the restoration of the vegetated and paved surfaces disturbed during system installation.  Additionally, National Grid will install the oxygen generation enclosure that will generate the oxygen for the delivery wells.

Starting in September or October, National Grid plans to start installing a similar oxygenation system (System #1) along Smith Street, the inactive LIRR right of way, and a short section along Hilton Ave.  This system will require approximately three to four months for installation.  As with the first system, excavating equipment will be used for digging piping trenches. Based on the completed environmental investigations in the area, the shallow soils to be excavated are not contaminated from the former MGP Site. Each day, after wells and lines are installed, the trenches will be secured. After all of the work is done, the areas will be fully restored.

The work will be conducted with oversight from the New York State Department of Environmental Conservation, the New York State Department of Health, and the Nassau County Department of Health.

National Grid has also made progress with the plans for remediating the residual MGP materials located at the former site itself, and under the parking lot immediately to the south of the MGP Site.  This soil remediation work will use solidification with cement and other additives to encapsulate the MGP residuals in these areas.  National Grid intends to solicit bids for this work phase during the Fall of 2010, and commence work on this phase of the program in 2011. 

Should you have any questions or concerns about the work, please use National Grid’s Hempstead Intersection Street Project Hotline at 516 545 6161. Additional information about the investigation and remediation of the Hempstead Intersection Street former MGP Site is also available on the project website at www.hempsteadintersectionstreetmgpsite.com

Thank you for your cooperation as we continue to make progress addressing the environmental issues associated with the Hempstead former Manufactured Gas Plant Site.

Soil Treatment and Groundwater Treatment Systems Map.pdf