16    DEVELOPMENT OF A STANDARD SAMPLING SYSTEM
FOR THE DETECTION OF VOLATILE COMBUSTIBLE
MATERIALS IN INDUSTRIAL DISCHARGES TO
PUBLIC SEWERAGE SYSTEMS
Linda M. Shadier, Project Engineer
Thomas E. Knapp, Project Engineer
Ross C. Caballero, Head, JWPCP Research Section
Paul C. Martyn, Head, Monitoring Section
County Sanitation Districts of Los Angeles
Whittier, California 90607
INTRODUCTION
The County Sanitation Districts of Los Angeles County (Districts) are a group of special districts
serving the wastewater and solid waste management needs of over four million people and 8,500
industrial users in Los Angeles County. The Districts own and operate eleven wastewater treatment
plants which treat over 1.9 million m3/d (500 mgd) of wastewater. Ninety-five percent of this flow is
transported and treated in the Joint Outfall System (JOS), which consists of six treatment plants,
1,900 kilometers (1,200 miles) of trunk line sewers and fifty pumping plants. The treated effluents
from the JOS are discharged to the ocean or to inland surface waters, and are used for irrigation,
groundwater recharge or industrial process water.
In 1972, Districts adopted a Wastewater Ordinance to protect and finance the operation of collection and treatment facilities. The Ordinance established the Industrial Waste Permit Program. The
Permit Program requires industrial dischargers to obtain a discharge permit for each industrial
wastewater connection to the sewerage system. Over 8,500 permits have been issued to date, for
industrial discharges totaling 269,000 m3/d (71 mgd). As part of the permit approval, dischargers
must provide plans that detail all monitoring and pretreatment facilities required by Districts. To
maintain a valid permit, dischargers must comply with all federal, state and local effluent limitations,
and all policies and guidelines for the measurement, monitoring or restriction of wastewater flows and
prohibited materials.
In 1971, Chicago, Illinois, instituted a plan to eliminate explosive conditions in their sewerage
system, after an explosion caused by a spill of coking wastes. Following the February 1981 explosion
of spilled hexane in the Louisville, Kentucky, sewerage system, in which four people were injured and
damages amounted to $51 million, there were attempts nationwide and at the Districts to implement
some form of industrial combustibles monitoring program. The Districts' response was the issuance of
the Combustible Gas Monitoring System (CGMS) Guidelines which require all significant potential
dischargers of flammable substances to install and maintain an accurate CGMS to protect downstream Districts' facilities and the local environment.
In August 1988, an explosion resulted from gasoline dumping in the Gloucester, Massachussetts,
sewerage system. The downtown area was evacuated for a time and several homes received minor
damage but no one was injured.
Although the federal government took no action in 1981, in 1988, the Environmental Protection
Agency proposed several amendments to the general pretreatment regulations (40 CFR 403) for
industries which discharge to publicly owned treatment works (POTW). The proposed regulations
included provisions for the prohibition of any discharge with a closed cup flash point of less than
60°C (140°F) or which causes concentrations greater than 10 percent of the Lower Explosive Limit
(LEL) as methane anywhere in the POTW. The proposed regulation may also require POTWs to
develop numerical limits or other controls to eliminate discharges which could produce "toxic gases,
vapors, or fumes within a POTW in a quantity that may cause acute worker health and safety
problems."
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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