2    IN-SITU REMEDIATION OF A HYDROCHLORIC ACID SPILL
Kenneth H. Kastman, Senior Associate
Saad Ghalib, Project Engineer
Stanislaus J. Zagula, Chemical Engineer
Woodward-Clyde Consultants, Chicago, IL
INTRODUCTION
This paper summarizes a hydrochloric acid wastewater spill incident and the immediate response
taken. The paper describes the field investigations conducted at the site in order to identify the extent
of spill, the remedial actions taken and the follow-up investigations performed to confirm the success
of these remedial actions.
The hydrochloric acid (HC1) wastewater spill was discovered in May 1990 after two surface soil
depressions were noticed at the northeast and northwest corners of a sump pumping station. The
surface soil depressions at the sump corners were about 2 ft deep and 2 to 4 ft in diameter. The
hydrochloric acid wastewater sump was part of the industrial facility wastewater treatment system.
Upon visual inspection, it appeared that the spill occurred from the unlined concrete bottom of the
dry well side of the sump rather than the wet well side which was lined with acid resistent brick
materials.
The facility orally reported the spill incident to the appropriate State Agency immediately upon
discovery and followed with a written report within 14 days. The spilled fluid contained approximately 8 percent HC1 (by weight) and trace concentrations of non-hazardous constituents related to
facility operations.
After removal from service, both the dry and wet well sumps were filled with service water to
confirm and measure the loss of fluid. Monitoring of the water level drop over several hours indicated
that the wastewater outflow rate was approximately 8 gallons per minute (gpm). Calculating back to
when the spill may have occurred resulted in an estimated spill volume of 35,000 gallons of lost
fluids.
GENERAL SITE CONDITIONS
Previous geotechnical investigations for site buildings indicated that the industrial facility is in a
flood plain of a deep glacial filled valley of a major midwestern river. The general ground surface is
approximately 70 ft above the normal river level. The depth to bedrock is approximately 130 ft below
the general ground surface. The subsurface conditions are comprised of glacially deposited outwash
sands and gravel, generally fining upward. The industrial facility uses ground water for processing,
drawing water from wells that pump up to 1,000 gpm from the lower portions of the outwash
materials.
FIELD INVESTIGATION
A field investigation was initiated the day following discovery of the spill. A soil boring (SB-MW1)
was drilled to an 85 ft depth and soil samples collected. A 2-in. diameter PVC monitoring well (MW1)
was installed within 4 ft of the dry well sump. The field investigation was conducted under a modified
Level D Health and Safety protection program.
Soil Investigation
Soil samples were collected continuously by driving a 2-in. O.D. split spoon sampler prior to
advancing the boring by hollow stem auger methods. A total of 42 split spoon samples were collected
and 14 of the samples were sent to a laboratory for analytical testing. Split spoons were decontaminated with an Alconox solution wash and deionized water rinse before each sample was collected.
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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