Hayden Bridge Water Filtration Plant - Executive Summary |
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POLICY The Eugene Water & Electric Board (EWEB) is a public utility, and as such, it is incumbent upon the utility protect its employee's and the community from dangers inherent in the operation of providing reliable electricity and steam, and safe drinking water. EWEB's Hayden Bridge Water Filtration Plant (Water Plant) has been, and intends to continue to be in compliance with EPA and OSHA requirements for prevention and response of chemical releases. The Water Plant staff annually reviews and drills with its Process Hazards Analysis (PHA), Process Safety Management (PSM) plan and Emergency Action Plan (EAP). In addition, EWEB's Water Plant is annually inspected by the local emergency responders (City of Springfield Fire & Safety) and used as a drill practice site. REGULATED PROCESSES The Water Plant uses two toxic gases (chlorine and sulfur dioxide) in the processing of safe drinking water. To disinfect the raw water from the McKenzie River, chlorine gas is mixed with water at a concentration of up to 3.0 parts per million (ppm). After filtration, sulfur dioxide is used to dechlorinate the water to approximately 0.6 ppm chlorine. The levels of chlorine in the water drop in the distribution system, and normally the chlorine level in residences is between 0.2 and 0.25 ppm residual chlorine. The Federal Safe Drinking Water Act requires that drinking water contain a minimum of 0.20 ppm residual chlorine in the distribution system. The Hayden Bridge containment facility can hold up to twelve one-ton cylinders of chlorine gas (24,000 pounds) and up to four one-ton cylinders of sulfur dioxide (8,000 pounds). FACILITY DESIGN The Water Plant has taken several measures to protect the public in the event of a toxic gas release. Since it started operation in 1950, there have been no releases to the public: EWEB recently built a containment structure for chlorine and sulfur dioxide. The storage/process rooms have a redundant system of detectors. If a release is detect ed, the system closes the vents from the outside, and the gases are blown into a scrubber unit that is designed to neutralize the release. The scrubber is sized to handle a one-ton release of either chlorine or sulfur dioxide. The building is built to earthquake codes. The system has been checked and all of the computerized components are Y2K compliant. The chlorine and sulfur dioxide are fed through a vacuum system. In the event of a line break in the plant, the line loses its vacuum and the feeders shut down, preventing a release. In addition, EWEB has purchased its own one-ton cylinders so that we can be assured of, and monitor the integrity of the containers. One-ton cylinders are one of the safest methods for transporting and storing chlorine and sulfur dioxide. WORST CASE SCENARIO (to establish a public dialog area) The Water Plant's worst case scenario assumes that a 1-ton cylinder (the largest single container) stored inside the containment building released its entire cont ents in 10 minutes. After leaving the building and with 1.5 meter per second wind, the chlorine gas would travel an estimated 0.9 miles before its concentration was diluted to a safe concentration (0.0087 milligrams per liter). Using 0.9 miles as a radius, the estimated population that could be affected by a release is 1,650. Primarily the surrounding community is a mixture of agricultural, residential, heavy commercial and light industrial uses. No schools or hospitals are within the worst-case scenario radius. However, Briggs and Yolanda schools are just beyond the worst-case radius. ALTERNATIVE CASE SCENARIO (a realistic scenario to be used for accident prevention and response planing) Alternative release scenarios were evaluated for both chlorine and sulfur dioxide at Water Plant. The most likely scenario, with the largest potential impact would be a fuse-plug blowing out of either a chlorine or sulfur dioxide cylinder, causing the release of a large amount of the cylinders conte nts. Because of the containment buildings scrubber neutralization system, EWEB believes that any release from building would be at or below a safe concentration (0.0087 mg/L). However, for the purposes of the RMP, the calculated effectiveness of the scrubber unit was lowered to 95%. With a 1.5 meter per second wind, a plume would go 0.2 miles before it was at a safe concentration (0.0087 mg/L). The alternative case radius is just beyond the Water Plant boundaries, and includes several residences and one industrial facility. THE FIVE-YEAR ACCIDENT HISTORY The Water Plant has had one accident in the last five years. The accident involved a small release (about 1/3 pound) of sulfur dioxide that was a residue in a line that was disconnected. This was a design flaw in the old system which has been eliminated by the new vacuum feed system. The operator walked into the release (instead of away from it) and reported the inhalation exposure. The employee was taken in for a medical evaluation. The evaluation concluded that the exposure did not cause any harm, and the employee returned to work. ERROR MESSAGES There may be some error messages associated with this site. All of the error messages are "required field missing" errors. The reasons follows. Section 3 - Toxics: Alternative Scenario 2, fields 3.5 to 3.12: EWEB conducted the alternative release scenario for chlorine and sulfur dioxide, and both have the same results. The EPA's RMP*Submit program did not hold the data when it was entered for sulfur dioxide. Section 7 - Prevention Program 3, field 7.13: EWEB's Water Plant does not allow hot work (e.g., welding) in areas that would require a hot work permit. Therefore this field was intentionally left blank. |