Virtually the entire site is flat and covered with buildings or pavement. The surrounding neighborhood is primarily industrial and commercial, with some residential properties within a few blocks. To the south, across 12th Street, the New York City Board of Education maintains a two story office and supply building. Across 2nd Ave to the east is a municipally owned garbage truck maintenance facility. An active commercial property borders the site to the north, and the Gowanus Canal borders on the west. The site was occupied by a large manufactured gas plant (MGP) from the late 1800s to the 1930s. The MGP converted coal and petroleum products to gas, which was used for heating, cooking, and lighting purposes in the surrounding areas. The process produced large amounts of coal tar wastes which have heavily contaminated the soils beneath the site. The western third of the site (where the actual gas plant was located) is now occupied by a multi-story brick commercial building including a Pathmark grocery store. The remainder of the site, (which housed gas purification and storage facilities and three large gas holders) was redeveloped under DEC's Voluntary Cleanup Program in 2003 and now houses a large Lowe's building supply store. The US Postal Service Gowanus operated until 2000, when it was demolished for redevelopment. During the demolition and regrading of the site, the MGP gas holders were discovered, full of tar mixed with construction debris. Remediation included removal of the contents of the gas holder foundations and grossly contaminated soils in the surrounding areas to depths ranging from 4 to 16 feet. Tar contamination has penetrated deeper than this, down to depths of 60-80 feet; however, this material could not be reached by conventional excavation techniques and presents little danger of exposure. Some of the tar which was left behind at depth remains mobile in the subsurface. A series of passive tar recovery wells remain in service and continue to recover tar as of June, 2007. Tar is collected on a monthly basis, and shipped off site for proper treatment and disposal. No evidence of tar contamination entering the Gowanus Canal from this site has been found to date. However, tar contamination from a similar site nearby (Carroll Gardens) has been found entering the canal, and investigation of tar migration at this site remains incomplete. The remaining portion of the site (beneath the Pathmark store), and off site areas where tar and contaminated groundwater have migrated, were beyond the scope of the Voluntary Cleanup Agreement, and will be the responsibility of National Grid. Negotiations for a consent order are under way.
Site Environmental Assessment
The principal waste disposed on the site was MGP tar, which is a brown, oily liquid that is slightly denser than water. Large amounts of this tar escaped from the foundation of the gas holders, and appear to have migrated off site to the south and west of the site. The tar contains high levels of BTEX and PAH compounds. Both groups of compounds have been found in site groundwater. Soils and groundwater at the site are heavily impacted by BTEX and PAH compounds. The impacted soils are found at depths of 8-16 feet and greater beneath the Lowe's portion of the property; contaminated soils above this elevation were removed and replaced with clean backfill during the remedial action in 2002. No information is available on the Pathmark portion of the site. However, gross contamination was found within a few feet of the Pathmark foundation and it is likely that significant amounts of soil and groundwater contamination are present in this area also. Soil and groundwater contain BTEX and PAH compounds at levels far in excess of SCGs. These exceedances represent a significant threat to the environment. The adjacent portion of the Gowanus Canal is heavily contaminated from a variety of sources, but specific impacts from this MGP site have not been identified. The off site tar migration appears to be taking place at depths below the bottom of the canal. Site Health Assessment
Further investigation is needed to assess the nature and extent of site-related contamination and the potential for exposure to site contaminants. The site currently has several buildings and a paved parking lot, therefore, contact with subsurface contamination is unlikely. Exposure to site-related contaminants in groundwater is not expected because the area is served by public water. NYSDOH and NYSDEC will evaluate the need for additional investigations to determine the potential for soil vapor intrusion on the site. Contaminants of Concern
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