14    GASOLINE CONTAMINATED GROUND WATER
TREATMENT STUDY
A. Rony Joel, Associate
Camp, Dresser & McKee, Inc.
Pittsburgh, Pennsylvania 15106
Peter Gerbasi, Environmental Engineer
Camp, Dresser & McKee, Inc.
Woodbury, New York 11797
INTRODUCTION
In November 1987, groundwater underlying a large marketing and distribution terminal in eastern
New York was found to be contaminated with leaded gasoline (dissolved and free product), methylene
chloride (MC), and trichloroethylene (TCE). The source of the gasoline was determined to be a small
hole in a buried pipeline under a tank loading rack. The source of the MC and TCE was determined to
be a leak in an onsite vapor recovery system which makes use of these chemicals as deicers and
refrigerants to condense gasoline vapors. After finding these leaks, all piping was repaired and
pressure-tested before being returned to service.
Analysis of groundwater samples from monitoring wells in the area show that some are contaminated with gasoline constituents, come with MC and TCE, and some with both. The gasoline-
contaminated water samples contain benzene, toluene, ethylbenzene and xylenes (collectively referred
to as BTEX). The BTEX compounds make up approximately 20% by weight of the constituents in
gasoline. In addition to BTEX, the other major constituents found in the gasoline are ethylene
dichloride (EDC), ethylene dibromide (EDB), methyl tertiary butyl ether (MTBE), and lead.
DISCUSSION
As part of a full-service engineering program for remediation of the contamination. We were
engaged to conduct a treatability study for the purposes of screening various treatment technologies to
demonstrate that they would successfully remove the contaminants, and establishing design criteria
for a full-scale treatment facility.
After the gasoline contamination of the groundwater was discovered, ejector pumps were installed
in several monitoring wells to recover the pure product. To date, some 2 million liters of gasoline have
been recovered. A groundwater recovery well was also installed to intercept the dissolved contaminant
groundwater plume and control the migration of a "finger" of pure product to the west of the
northwest corner of the terminal's leased property. An air stripping tower, with vapor phase activated
carbon units to treat the air discharge, was put on-line as an interim remedial measure to treat the
intercepted groundwater. Currently, the air stripping unit is treating up to 280 liters per minute.
In the contaminated groundwater, the volatile organic chemicals (VOCs) of greatest concern consist
of gasoline components and solvents. The highest concentrations are those of the BTEX compounds.
Present in lower concentrations are the gasoline additives, ethylene dibromide (1,2-dibromoethane, or
EDB), and ethylene dichloride (1,2-dichloroethane, or KEDC). The solvents are methylene chloride
and trichloroethylene (TCE).
The primary component of inorganic contamination are metals, specifically lead, iron and manganese. Based on data from site monitoring, lead appears to be present at levels high enough to
necessitate its removal. Results of the pilot study indicated that iron and manganese would also
require removal. Table I presents the contaminant concentration and effluent limits imposed by the
regulators.
47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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