MSD has posted signs at all combined sewer overflows, retrofitted deep sewer-access holes with locking lids and found substitutes for cleaning agents judged to pose potential risk to housekeepers.

Federal OSHA (Occupational Safety & Health Administration) rules require MSD (and many other local industries) to do "process safety management." PSM calls for preventing or reducing the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals. PSM must be done for any process involving a chemical at or above the certain "threshold quantities" listed in Appendix A of the rule.

The Morris Forman Wastewater Treatment Plant (MFWTP) historically used  90-ton tank cars of chlorine for disinfection. The West County Wastewater Treatment Plant (WCWTP) used one-ton cylinders of chlorine for the same purpose. Both quantities exceed the threshold quantity of 1500 pounds for chlorine.

Exposure to chlorine can cause coughing and breathing difficulties. Heavy exposure can irritate, burn or severely damage skin, eyes and lungs, requiring prompt medical attention. Gross over-exposure can cause death.

MSD has safety systems in place at both MFWTP and WCWTP to prevent chlorine releases. We haven’t had an accidental release of chlorine beyond plant boundaries in over a decade.

Despite this exceptional safety record, MSD converted from chlorine to sodium hypochlorite for disinfection in June, 1999. This conversion eliminated the potential of a catastrophic release of chlorine. Typical of pollution prevention strategies, this conversion provides many benefits: improved worker safety, eliminated public risk, improved "Good Neighbor" status, reduced energy costs and reduced air pollution.

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