87    CENTRALIZED TREATMENT OF NONHAZARDOUS
WASTES; AN ALTERNATIVE MEANS OF LIQUID
WASTE DISPOSAL
Mark W. Miller, Project Engineer
M. Philip Lo, Senior Engineer
Suzanne S. Wienke, Project Engineer
Jay G. Kremer, Head, Industrial Waste Section
Sanitation Districts of Los Angeles County
Whittier, California 90607
NEED FOR NONHAZARDOUS CENTRALIZED WASTE TREATMENT
The days are numbered for the disposal of liquid and semi-solid wastes in municipal landfills.
California State regulations will ban the disposal of both bulk liquid and semi-solid wastes in landfills. Generators of nonhazardous wastes not suitable for direct sewer disposal will be particularly
impacted by these measures and will be forced to seek alternative methods of waste disposal. Moreover, it is important to sewerage agencies that alternative disposal methods be available since a poorly
maintained clarifier or grease trap will allow solids and oil and grease to carry over to the sewer, thus
increasing costs for sewer cleaning and increasing incidents of sewer clogging and sewage overflow.
In California, liquid and semi-solid wastes are effectively banned from all classes of solid waste
landfills by the revised regulation for the discharge of waste to land.> This restriction in the disposal of
liquid and semi-solid wastes affects all three types of landfills in California:
1. Class I—Hazardous Waste Disposal Site. No disposal of liquid wastes without prior
treatment to remove free liquid.
2. Class II— Special Waste Disposal Site. No disposal of waste that contains liquid in excess
of the moisture-holding capacity of the waste in the landfill. However, the
landfill must be equipped as an impoundment to prevent leakages. There are
only a very limited number of these kinds of sites in California.
3. Class III—Municipal Waste Disposal Site. No disposal of liquid or semi-solid wastes
other than dewatered sewage sludges or water treatment sludges.
The revised regulations were adopted in October 1984; however, existing landfills may continue to
operate in accordance with their existing permits until a new permit is issued. All landfills in California are scheduled to be issued new operating permits in conformance with the adopted regulations by
October 14, 1989. At that time, bulk liquid wastes will be generally displaced from solid waste
landfills.
On the Federal level, the draft solid waste regulations under 40 CFR Part 257, Criteria for Municipal Solid Waste Landfills, will also ban liquid wastes from landfills under Subpart C, Section 258.28,
Liquid Restrictions. The draft regulation is expected to be proposed in the spring of 1988 and
finalized in 1989. The ban of liquid waste disposal would be in effect 18 months from the promulgation date in late 1990. Therefore, on the Federal level, liquid wastes will also be displaced from solid
waste landfills.
Sewerage agencies or city public works departments have required grease traps or sand and grease
interceptors for those users of the sewerage system that have the potential for discharging excessive
amounts of grit and/or oil and grease. The purpose of the grease traps or interceptors is to remove the
majority of the sand and grit and oil and grease from the wastewater before it enters the public
sewerage system. Plan and sectional views of the grease trap and the sand and grease interceptor are
given in Figures 1 and 2, respectively. This serves to decrease the frequency of scheduled sewer
cleaning and to minimize emergency cleaning in the event of sewer blockages attributed to grit or oil
and grease accumulation. The grease traps and interceptors must be pumped out periodically to
43rd Purdue Industrial Waste Conference Proceedings, © 1989 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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