Section Eight
VOLATILE ORGANIC CHEMICALS
60    CONTROL AND REMEDIATION OF SOLVENT
POLLUTION IN THE DRY CLEANING INDUSTRY: A
TECHNOLOGICAL ASSESSMENT
John R. Johnston, Associate Professor
Department of Civil and Surveying Engineering and Construction
California State University
Fresno, California 93711
George Tchobanoglous, Professor Emeritus
Department of Civil and Environmental Engineering
University of California, Davis
Davis, California 95616
George P. Hanna, Jr., Director
Engineering Research Institute and Professor Emeritus
California State University
Fresno, California 93711
INTRODUCTION
Dry cleaning is the commercial laundering of clothes using organic solvents rather than water.
The most popular solvent, used in about 85% of the 4,800 dry cleaning establishments in California, is PCE (perchloroethylene, also known by the more precise name of tetrachloroethylene
or the abbreviation, "PERC").1 PCE is a colorless, organic, nonaqueous-phase liquid (NAPL)
that is nonionic, nonpolar, and exhibits negligible photoreactivity. It is heavier than water (specific gravity of 1.6), relatively insoluble in water (solubility of 150 mg/L), and relatively volatile.
PCE is also a Class C (possible) human carcinogen.
In recent years, PCE has come under increasingly stringent regulation in California and other
states. PCE is classified as a toxic air pollutant and it has been found in groundwater in many locations. In California's Central Valley, for instance, a number of public water supply wells contain PCE in excess of the drinking water Maximum Contaminant Level of 5 ppb. PCE is used as
an industrial solvent and can even be found in some household products, but the dry cleaning industry accounts for 60% of the PCE sold in California.2 Dry cleaning establishments have been
identified as a source of fugitive atmospheric emissions and it is thought that dry cleaners are an
important contributor to groundwater contamination in many locations.
Recognizing the environmental problems associated with the dry cleaning industry, the California legislature enacted Assembly Bill 2370 in 1992, which created the California Dry Cleaning Industry Task Force, comprised of representatives from regulatory agencies, the dry cleaning
industry, the Legislature, and concerned citizens. A technical background report on the pollution
problems of California's dry cleaning industry was prepared for the Task Force by researchers
from California State University Fresno and the University of California, Davis. This paper is
extracted from that report.3
Pollution problems in the dry cleaning industry fall into two categories. The first concerns the
containment and control of dry cleaning solvents to minimize fugitive losses to the environment
from existing operations. The second category concerns the mitigation or cleanup of soil and
50th Purdue Industrial Waste Conference Proceedings, 1995, Ann Arbor Press, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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