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[A printed copy summarizing the results of the U.S. EPA removal action is available at the Riverfront Site data Repository located at the New Haven Public Library]
 Backfilling excavations at OU1 with clean fill. |
A water supply line located in operable unit 1 (OU-1) had to be removed due to the presence of tetrachloroethene (PCE) in water from an outdoor faucet (referred to as the "dog pen faucet") next to the city dog pound and in water from a sink faucet in the public restroom located at the Riverfront Landing parking area. These two locations are unique because they are served by a plastic waterline that ran along the south side of the Riverfront Site (image). |
This contamination was initially detected by the U.S. Geological Survey (USGS) on May 11, 2000. Water from the dog pen faucet was used to wash field sampling equipment. As is standard practice, samples of the rinse water were analyzed by a portable gas chromatograph (GC) to ensure the equipment was not contaminated by the wash water. Following the initial detection, a reconnaissance sampling in late May 2000 of water from fire hydrants, and faucets in nearby homes and businesses indicated that the contamination was restricted to the two faucets served by the plastic waterline. After results of laboratory analysis verified the field reconnaissance, an emergency removal action was initiated by the U.S. EPA to reduce the potential human exposure to PCE. The removal action consisted of replacing the contaminated waterline and removing nearby contaminated soils.
During late June and early July, 2000, the U.S. EPA's Emergency and Rapid Response Services (RACS) contractor was mobilized in the area to perform soil sampling around the waterline and to design its replacement. Plastic is permeable to organic vapors, such as PCE, and the results of the soil sampling indicated that PCE concentrations in nearby soils and in soil vapor, probably were large enough to contaminate the waterline through direct contact or by migration of PCE vapors into the line. The U.S. EPA oversaw the removal of the waterline and the installation of a new ductile-iron waterline with chemical resistant gaskets. On August 7, 2000, water samples were collected at the public restroom sink, the dog pen faucet and, a fire hydrant immediately "upstream" of the new waterline. None of the water samples contained detectable concentrations of PCE, indicating the removal action had been effective.
On August 14, 2000, the excavation of additional PCE contaminated soils beneath Front Street in the vicinity of the waterline (image) brought the total amount of soil removed to 762 tons. Because the site is within 500 ft of the flood protection levee surrounding New Haven, the excavation depths were limited to 8 ft and were required to be backfilled to 95 percent compaction at the conclusion of each work day. The USGS assisted the RACS contractor by providing a mobile laboratory for the characterization of PCE concentrations in the removed soils as the excavations proceeded.
Analysis of f samples from the dog pen faucet collected in October, November, and December 2000 and January 2001 using the portable GC has not detected the presence of PCE or related compounds.
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U.S. Department of the Interior, U.S. Geological Survey
Maintainer: John Schumacher and Rita Choate, Webmaster
Updated: January 13, 2005
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URL: http://mo.water.usgs.gov/epa/nh/WaterLine_Removal_files/index.htm