42    IN-SITU REMOVAL OF PURGEABLE ORGANIC
COMPOUNDS FROM VADOSE ZONE SOILS
Frederick C. Payne, President
Midwest Water Resource, Inc.
Charlotte, Michigan 48813
Charles P. Cubbage, President
Cubbage Environmental Control
Milford, Michigan 48042
Galen L. Kilmer, District Engineer
Groundwater Quality Division
Michigan Department of Natural Resources
Plainwell, Michigan 49080
Laurence H. Fish, Vice President
Custom Products, Inc.
Stevensville, Michigan 49127
INTRODUCTION
Our test site is located in Stevensville, Michigan, 0.9 miles east of the Lake Michigan shoreline, 18
miles north of the Indiana-Michigan border. During mid-1984, a purgeable organic contamination
plume was discovered in a useable aquifer, covering approximately 51 acres. Testing showed perchlo-
roethylene as the principal contaminant, reaching levels in excess of 100 ppb in domestic water wells
and levels of 800 ppb in nearby industrial production wells. Two light manufacturing facilities were
identified by the Michigan Department of Natural Resources as potentially responsible parties
(PRP's) under provisions of the Michigan Environmental Response Act.
Custom Products, Inc., one of the two PRP's identified by MDNR, had used PERC as a degreasing
solvent prior to discovery of groundwater contamination in the area. The company retained Water
Quality Investigators and Midwest Water Resource, Inc. to conduct soil and hydrogeological studies
in the vicinity of its sheet metal forming facility.
Soil surface samples were collected in February 1985 for analysis of purgeable aromatic and
chlorinated solvents. These tests showed three potential loading points for volatile organic compounds into the soils and groundwater: 1) a location outside the building where solvents had been
stored; 2) an interior drywell which drained the paint spray booth; and 3) a location outside an
exterior wall where a pipe once exhausted PERC tank sludge which recycling haulers would not
accept. The sludge discharge location later proved to be the major loading point and showed 110 mg/
kg PERC in the February 1985 soil surface sampling.
A 9-point triangular grid pattern was established for soil borings outside the building (Figure 1).
This grid had a 5-point base leg (A-E) with 25-foot separation between boring points; the center point
on the base leg (C) was placed at the sludge discharge point. A second tier of three borings (F-H) was
placed parallel to the base leg 25 feet from the wall with 25-foot separation between points. A final
boring (I) was placed 50 feet from the wall perpendicular to the known discharge point. Three
additional borings (J-L) were placed through the floor of the building, 20 feel from the exterior wall.
The soil borings were conducted with a hollow-stem auger with split-spoon samples taken at 5-foot
intervals. Soil samples were placed in Teflon-capped VOA bottles, stored on ice, and carried to
Canton Analytical Laboratory, Ypsilanti, Michigan for immediate analysis of purgeable aromatics
and purgeable halocarbons. Two borings showed measureable levels of purgeables — the boring
located at the sludge discharge point (C), and one of the three borings within 25 feet of the discharge
point (B). Table I gives the results of laboratory analysis for these two borings.
All borings showed fine sand throughout the vadose zone, which extended to the 30-foot depth.
The volume of contaminated soil was estimated lo be between 1,000 and 2,000 cubic yards. More
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