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NAWC West Trenton - Site Description
The former Naval Air Warfare Center (NAWC) was a U.S. Navy jet engine testing facility for military aircraft from the mid-1950ís until the late 1990ís. As a result of the activities at the facility, tricholoethlylene (TCE), jet fuel, and other chemicals have leaked into the subsurface. The NAWC covers 67 acres and has large jet-engine test buildings, associated service buildings, hangers, and scores of smaller support structures all interconnected with a vast network of aboveground and underground service lines.
NAWC was decommissioned on October 15, 1998 and has been divided and sold. It is bordered by the Trenton-Mercer Airport on the east, north, and west and by Parkway Avenue on the south. Commercial and industrial firms occupy the south side of Parkway Avenue. Freight train tracks separate the eastern from the western part of the base.
Investigations of the groundwater contamination at the site began in the late 1980's. By the mid-1990's, the pump and treat facility was in operation. The Navy demonstrated to the EPA that the pump and treat facility remedy was operating properly and successfully, limiting the migration of TCE and its degradation byproducts cis-1,2-dichloroethene (DCE) and vinyl chloride (VC).
on cross section to download a
The NAWC lies within the Newark Basin and is characterized by Triassic-age clastic sedimentary rocks, predominately mudstone in the Lockatong Formation, and sandstone in the Stockton Formation.
The general strike and dip is about N50oE and 30oNW. A fault with an approximate strike and dip of N50oE and 60oSE separates rocks of the Lockatong and Stockton Formations.
The natural topography in the area is characterized by low rolling hills; however, much of the base has been leveled and terraced to accommodate the NAWC and the airport runway.
The rocks are heavily weathered from land surface to a depth of about 5 ft and as a result, the bedrock behaves like an unconsolidated aquifer. Bedrock from 5 to 50 ft ranges from very weathered to unweathered. Water is transmitted in heavily weathered zones and in succinct fractures and partings. At depths greater than 50 ft below land surface, the bedrock is generally unweathered and water is transmitted via succinct fractures or partings. The unstressed regional hydraulic gradient in the bedrock aquifer is southward toward the west branch of Gold Run, but the groundwater flow direction is westward toward the spring. The cone of depression caused by pumping of contaminant and recovery wells at the site is asymmetric with a ratio of at least 4:1. The preferential flow directions in the bedrock aquifer are along bedding, strike, and dip.
TCE and jet fuel in the Site 1 area leaked onto land surface between building 40 and 41. Some of the TCE and the jet fuel were intercepted by storm sewer lines and discharged to a local creek, a tributary to the Delaware River. The remaining TCE evaporated, sorbed onto the sediments, and flowed downward into the fractured bedrock aquifer. The remaining jet fuel infiltrated to the water table. TCE that intercepted spilled jet fuel began to biodegrade rather rapidly. TCE that flowed deeply into the fractured bedrock did not biodegrade rapidly.
The following maps and sections show TCE, DCE, and VC concentrations at the NAWC.
(Click above images
for full-size versions)
A spring in the wooded area near the southwest corner of NAWC flows nearly all year. The spring forms the headwater of the west branch of Gold Run. Sometime before 1940, the west branch of Gold Run was diverted to the culvert constructed under the eastbound lanes of Parkway Ave., and in the 1970ís, a second culvert was built under the westbound lanes of Parkway Avenue. The two culverts carry surface- and groundwater discharge to the main stem of Gold Run.
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