About the Dangman former MGP Site

There are no photographs of the Dangman Manufactured Gas Plant which operated between before 1895 and sometime between 1906 and 1930. Above is a photograph of a plant believed to be similar to the Dangman facilities, operating in about the same period.

The former Dangman Park Manufactured Gas Plant (MGP) site (“the Site”) is located at 486 Neptune Avenue, Brooklyn, New York.  The Site is located approximately 1,300 feet southeast of Coney Island Creek and approximately 2,400 feet north of New York Bay.  The Site is generally flat.  

The Site is located in the Coney Island community district of Brooklyn on approximately 1 acre of land, and is contained within modern Tax Lots 1 and 25 of Block 7273, which are bounded by Neptune Avenue to the north, W. 5th Street to the east, a residential parcel to the south, and a commercial parcel to the west.  Currently, the Site is developed with a shopping center and its parking lot, and a parking lot for an adjacent apartment building.

The Site was operated by the Brooklyn Borough Gas Company, which was a predecessor company to National Grid.

Based on a review of available historical information, the Site was used as an MGP from prior to 1895 until sometime between 1906 and 1930, probably about 1914.  The 1895 Sanborn map shows two gas holders, a retort house, two oil tanks, a tar tank, an engine room, a purifying house and a shed.  By 1906, an additional gas holder, generating house and cistern had been constructed, and the retort house and tar tank were no longer present.  The MGP structures were removed sometime between 1906 and 1930.  By 1930, all the MGP structures had been removed from the surface, and the Site was occupied by a club house.  By 1966, the Trump Village Shopping Center occupied the northern and central portions of the Site. 

National Grid conducted a Site Characterization (SC) in 2009-2010 and a Remedial Investigation (RI) in 2011-2013.  The investigations determined the extent of MGP-related constituents of concern (COCs), and determined that there were no complete exposure pathways to the COCs for commercial workers, patrons, or residents based on current land use. Based on the data collected, the following are the findings and conclusions:

  • Soil samples were collected from various depths beneath the Site.  The principal contaminant of concern is coal tar.  Coal tar contains compounds known as volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs); the concentrations of these compounds correlates with the observations of coal tar in the soils.  These compounds are frequently associated with former MGP operations.  Cyanide, metals, polychlorinated biphenyls (PCBs), and pesticides were detected in soil, but not identified as COCs.  These constituents may be present at the Site due to the placement of fill material after the closure of the MGP.  The lateral and vertical extent of the soil impacts has been determined by the RI.
  • In addition to coal tar contamination, some petroleum contamination was detected in the subsurface soil.  The origin of this contamination is not fully defined – it may have originated at the MGP, or it may have come from subsequent land uses in the roughly 100 year period since the MGP closed.  Some combination of these two sources is also possible.  The observed petroleum contamination is not uncommon in urban environments with industrial histories, such as the NYC area.

    • People are not expected to come in direct contact with contaminated soils because the entire site is covered with buildings or paved parking lots.  People may be exposed to contaminated soils if excavation occurs.  The NYSDEC must be notified if excavation work is anticipated on the site so that the appropriate controls can be put in place to manage the soils safely.
  • Groundwater samples were collected from monitoring wells installed at the Site.  The primary VOCs and SVOCs that were detected in groundwater are consistent with the compounds detected in the soil.  Cyanide, metals, PCBs and pesticides were not identified as COCs in groundwater.  The lateral and vertical extent of the groundwater impacts has been determined by the RI.

    • People are not drinking the contaminated groundwater because the area is served by a public water supply that is not affected by this contamination.

    • Contaminant concentrations in groundwater decrease rapidly with increasing distance from the former MGP location.
  • Gasoline, fuel oil, coal tar, other petroleum products, and solvents are examples of non-aqueous phase liquids (NAPLs).  No NAPLs were detected in any of the monitoring wells.
  • Soil vapor is the gas (e.g., air, and potential COCs) that fills space between soil particles.  Soil vapor samples were collected from beneath the shopping center parking lot, beneath the apartment building grass area, and beneath the floor slab of the shopping center building; and indoor air quality samples were collected from inside the shopping center building.  Soil vapor intrusion is the process by which volatile organic compounds can migrate from the subsurface into the indoor air of overlying buildings.

    • MGP-related contaminants were detected in vapor samples beneath the floor slab of the shopping center.  However, it does not appear that these contaminants are migrating into the overlying buildings at levels that require action to address exposure.  MGP-related contaminants detected in indoor air were consistently below typical background indoor air concentrations.  In addition, some of these same chemicals are used in cleaners and household products present in the shopping center.

    • Non-MGP-related constituents, including chlorinated hydrocarbon vapors, were detected in sub-slab soil vapor and indoor air samples, above typical background indoor air concentrations in some of the indoor air quality samples. Chlorinated VOCs are not associated with the former MGP operations.

  • The hydrocarbon product identification data from soil samples suggest that fuel oil impacts of unknown origin are present at the water table across the entire area that the former MGP occupied, and that coal tar impacts are present at the water table across the central and eastern portion of the area that the former MGP occupied.

  • The former MGP gas holders, tar tank, and cistern are all likely sources of the tar releases from the former MGP.  Tar-impacted soils were observed in the glacial outwash deposits underlying the Site.  The extent of tar-impacted soil has been horizontally and vertically delineated.