Boston, Mass. -- EPA has completed the second five-year review of the remedial actions previously implemented at the Pine Street Canal Superfund Site located in Burlington, Chittenden County, Vermont. Five-year reviews are mandated under the Comprehensive Environmental Response, Compensation and Liability Act (commonly known as “Superfund”).
This second five-year review concluded that while the remedy at Pine Street Canal is protective for most pathways of exposure to contaminants, a protectiveness determination of the remedy at the Site cannot be made until further information is obtained to evaluate potential vapor intrusion impacts at the existing Burlington Electric Department building. The vapor instruction study will also examine how to consider the potential for future vapor intrusion on the undeveloped parcels near the Site. Once the data are collected, they will be assessed and a determination will be made as to whether or not additional measures are necessary to ensure protection of human health. It is expected that these actions will take approximately 12 months to complete, at which time a protectiveness determination will be made. The Second Five-Year Review Report was signed on December 22, 2011.
In addition, in order for the remedy to be protective in the long-term, provisions of an Explanation of Significant Differences (ESD) issued by EPA in September 2011 must be implemented. The ESD calls for certain enhancements to the containment remedy to protect Lake Champlain from potentially being impacted by the migration of contaminated groundwater and coal tar left on site. Design work for this containment is underway and construction is expected to start in the summer and be completed by the end of the calendar year.
The Pine Street Canal Site consists of an abandoned barge canal and turning basin, surrounding vegetated wetlands, and upland areas. It is hydraulically connected to Lake Champlain and is subject to flooding from the lake. The Site has been used for various industrial and commercial purposes since the mid-1800s. Around 1895, Burlington Gas Works, a manufactured gas plant, was constructed on Pine Street, just north of what is now the Burlington Electric Department. The plant used a coal gasification process to manufacture gas for the city. Burlington Gas Works reportedly disposed of large quantities of coal gasification wastes, such as coal tar, fuel oil, cyanide, contaminated wood chips, iron oxide, cinders, and metals at its former location along Pine Street and in the wetlands behind the plant. These waste materials are the primary source of contamination at the Site.
The selected remedial action for the Site in the 1998 Record of Decision included capping contaminated sediments within the canal, turning basin and certain emergent wetland areas where an unacceptable ecological risk was found, effectively isolating the contamination below the biologically-active zone. A weir was constructed at the mouth of the turning basin; aquatic and wetland habitat restoration is being conducted; and stormwater management features were enhanced. The remedy also included establishing institutional controls to prevent the use of on-site groundwater for drinking water, prevent or limit the migration of existing contamination, and prevent certain land uses that could result in unacceptable human-health risks. Additionally, the remedy included long-term performance monitoring of groundwater, surface water, stormwater, sediments, as well as the cap. In 2009, EPA issued an Explanation of Significant Differences (ESD) that called for modifications to the sand cap; an amended cap was constructed in 2011.