TABLE 2-4 Reductions in Los Angeles County Wastewater Influent Loadings from 1975 to 1995

Constituent

Percent Reduction

Arsenic

68

Cadmium

92

Chromium

95

Copper

58

Lead

92

Mercury

46

Nickel

77

Zinc

73

Cyanide

95

Total identifiable chlorinated hydrocarbons

99

 

SOURCE: County Sanitation Districts of Los Angeles County, 1995.

tibility of the Hookers Point AWT facility to an upset due to an industrial user's release of chemicals to the sanitary sewer system (CH2M Hill, 1993). Of the service area's 45 industrial users, 31 already had emergency provisions to divert a catastrophic chemical release away from the sewers. A detailed evaluation was made of the 14 remaining industrial users with floor-drain connections to the sewer system to determine the potential for accidental spills. Evaluations were made of emergency response plans and the potential effects of a chemical spill on the AWT facility. It was concluded that the AWT facility was well protected from plant upset, pass-through, or interference due to an accidental spill of chemicals at an industrial user's facility. This type of vulnerability assessment can be quite useful for gathering the information necessary for emergency contingency planning as well as to provide safety assurance for the technical operation of potable reuse. (Chapter 6 contains a discussion of treatment plant reliability.)

Table 2-5 summarizes the concentrations of certain priority organic pollutants following secondary biological treatment in four different municipal districts as of 1987: Washington, D.C.; Orange County, California; Phoenix, Arizona; and Palo Alto, California. The Palo Alto system receives wastewater from a typical residential/commercial community as well as from a major university and from several electronics industries. Its wastewater contains high concentrations of chlorinated solvents. The Orange County wastewater comes from a variety of industries as well as municipal and commercial activities; it contains relatively high concentrations of petroleum-related chemicals, including various aromatic hy-



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement