While surface oil spills can often be cleaned up quickly and efficiently using absorbent materials and vacuums, underground accumulations of petroleum product – such as the one in Greenpoint – are typically more difficult to reach and take much longer to recover.
ExxonMobil’s goal is to remediate the petroleum contamination stemming from our historical operations in Greenpoint as quickly and safely as possible. This includes recovery of product, treatment of water, and monitoring and addressing soil vapors.
To date, more than 12.9 million gallons of petroleum products have been recovered and 3.5 billion gallons of water have been treated. ExxonMobil is committed to conducting a thorough and effective recovery, and continues to assess on a regular basis ways to enhance and optimize its recovery operation.
According to the 2007 U.S. Environmental Protection Agency Report, the dual-pump recovery is the most efficient and best sub-surface option for remediating the petroleum contamination underneath a section of Greenpoint. The system recovers product by depressing the water table around the recovery well to create a cone of depression which allows the petroleum products to flow into the recovery well. One pump in the recovery well removes the water, and the other pump removes petroleum products into storage tanks.
Groundwater removed by the dual-pump system is treated to remove contaminants, and tested to ensure its compliance with state and local regulations before being released into Newtown Creek.
- Water entering the system is held in a stabilization tank to allow it to settle.
- Air is injected into the water and passes it through filters that remove iron and magnesium.
- Petroleum components are removed from the groundwater by a process called air stripping. ExxonMobil’s process injects air through the water as it cascades down through a series of trays with holes of decreasing size that strip the contaminants from the water.
- Treated water is piped to one of two discharge points into Newtown Creek.
- During typical operation the recovery system pumps and treats up to 15 million gallons of groundwater each month.
- The discharged groundwater is sampled monthly and results are reported to the New York State Department of Environmental Conservation.
ExxonMobil regularly samples and evaluates subsurface soil vapors in Greenpoint in accordance with New York State Department of Health (NYSDOH) guidance. Air vapor tests were conducted on 52 homes from January to March 2007. No evidence was found of petroleum vapor intrusion from the underground contamination in residential homes.
Results of the New York State Department of Health and New York State Department of Environmental Conservation vapor studies can be found in the Greenpoint Petroleum Remediation Project (Off-Site Plume Area) Vapor Intrusion/Indoor Air Sampling report and in the Agency for Toxic Substances and Disease Registry Letter Health Consultation.
Soil vapor results:
- ExxonMobil’s investigations in residential areas show no unusual soil vapor concentrations above the contaminated area and are similar to background concentration results. These concentrations are also consistent with readings outside the contaminated area, according to a study conducted by the NYSDOH.
- Based on our findings, the contaminated area is not impacting shallow soil vapor beneath the residential area, and shallow soil vapor does not pose a health concern in this area. Scheduled and thorough soil vapor monitoring helps ensure public health.
- In 2005, during ExxonMobil’s bi-annual soil vapor testing of all property near the area of petroleum contamination in Greenpoint, elevated soil vapor concentrations were found in the shallow subsurface in isolated sections of the industrial/commercial area of Greenpoint.
- ExxonMobil took immediate action and did two things: conducted indoor air testing and began a thorough investigation to determine the source of the soil vapors. ExxonMobil continues to sample soil vapor twice each year and report the results to the New York State Department of Environmental Conservation (NYSDEC).
- Indoor air testing: ExxonMobil conducted indoor air testing within offices located in the industrial/commercial area and the investigation indicated there were no indoor air quality impacts associated with vapor intrusion. These findings were submitted and approved by the NYSDEC.
- Soil vapors: When ExxonMobil discovered the soil vapor data, it began a thorough investigation process to determine the source of the elevated soil vapor concentration levels and the precise location of the impacted area. Through the research, ExxonMobil was able to determine the perimeter of the affected area and determine the appropriate remediation strategy. The state has approved the soil vapor remediation plan, which includes creation of a soil vapor treatment facility, and outlines a remediation schedule.
The ExxonMobil Soil Vapor Extraction System for the isolated area at the intersection of Bridgewater, Apollo and Norman Avenues construction has been completed and is currently operating with an interim system as of August 24, 2009. The full system operation is scheduled for the end of the first quarter of 2010.
Air vapor results:
- In 2007, NYSDEC and NYSDOH conducted an air vapor intrusion investigation in the residential area. Samples taken underneath foundation slabs were compared with basement and first floor samples, as well as outdoor samples, with consistent results: no petroleum air vapors have been linked to the underground petroleum contamination based upon the state’s research.
- ExxonMobil monitors street utility manholes throughout the area above the petroleum contamination. No elevated vapor readings have been found.
- ExxonMobil also monitors ongoing and planned construction in both the residential neighborhood and commercial/industrial zones above the underground contamination. We contact parties responsible for construction to ensure that appropriate procedures for digging or excavating are followed.
Read more on the NYSDEC Web site »
Residents who detect petroleum odors are encouraged to contact the New York State Spill Hotline at 800-457-7362.
If you believe you are in the area over the petroleum contamination and are interested in having your home sampled, please contact the NYSDEC’s Project Manager, Edward Hampston at (888) 459-8667 or firstname.lastname@example.org