11    INNOVATIVE GROUNDWATER REMEDIATION
SOLUTIONS FOR THE MERCURY AIRCRAFT SITE
Thomas H. Forbes, Project Engineer
Richard H. Frappa, Project Hydrologist
Anne Marie C. McManus, Associate
Malcolm Pirnie, Inc.
Buffalo, New York 14219
INTRODUCTION
Complex hydrogeologic conditions and groundwater contaminated with high concentrations of
chlorinated solvents are common remediation problems at many industrial sites in New York
State. This paper presents the results of an innovative remedial alternative implemented as an Interim Remedial Measure at the Mercury Aircraft site. The densely fractured bedrock conditions
at this site precluded the cost-effective use of traditional individual pumping wells and/or in-situ
groundwater treatment to mitigate the spread of contaminated groundwater. In addition, the high
concentrations of VOCs presented a concern with respect to New York State air emissions limits
for conventional ex-situ treatment technologies. The remedial alternatives evaluated and the
specifics of implementation of the selected alternative are presented along with performance
results.
BACKGROUND
Mercury Aircraft owns a five-acre site including a manufacturing facility located 800 feet from
the western shore of Seneca Lake in the Finger Lakes Region of New York State (see Figure 1).
In 1985, an estimated 300 to 500 gallon trichloroethene (TCE) spill occurred from a vapor de-
greasing process at Mercury Aircraft's manufacturing building. Much of the TCE was recovered
during spill response cleanup operations; however, some TCE migrated through a seam in the
floor of the vapor degreasing area and entered a leaky storm sewer beneath the facility.
After the initial cleanup, the storm water discharge was monitored for TCE and continued to
indicate the presence of TCE in the ppm range. At the direction of the New York State Department of Environmental Conservation (NYSDEC), a preliminary site assessment and a subsequent subsurface site investigation were conducted in 1989 to evaluate the impact to the groundwater at the site. Additional investigative work was conducted in 1992. Investigations including
a qualitative soil gas survey and a monitoring well installation/sampling program identified the
presence of a chlorinated volatile organic groundwater plume downgradient of the Mercury Aircraft building (see Figure 2). The plume contained TCE with its associated degradation products
(1,2-dichloroethene and vinyl chloride), as well as 1,1,1-trichloroethane and 1,1-dichloroethane
at total VOC concentrations exceeding 100 ppm within the water-bearing shale bedrock. An Interim Remedial Measure (IRM) was implemented to quickly control the spread of contaminant
migration and mitigate the potential risk to human health and the environment. The IRM included an evaluation of hydraulic controls and treatment technologies leading to the design and
construction of a groundwater collection and treatment system.
GEOLOGY/HYDROGEOLOGY
Mercury Aircraft is located on the western edge of the glaciated trough of Seneca Lake. The
glacial valley slopes moderately toward the surface of the lake and plunges to a depth of more
50th Purdue Industrial Waste Conference Proceedings, 1995, Ann Arbor Press, Inc., Chelsea. Michigan 48118.
Printed in U.S.A.
97