Rapid City Water Reclamation Facility - Executive Summary

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Executive Summary 
Accidental release, & emergency response policies 
The City of Rapid City Water Reclamation Division accidental release prevention policy utilizes passive and active mitigation technologies as well as operational and management procedures.  The emergency response plan is designed in accordance with the U.S. Environmental Protection Agency prevention program.  This policy utilizes the Emergency response services available from the Rapid City Fire Department HAZMAT team. 
The stationary source and substances handled 
The Rapid City Water Reclamation facility treats the wastewater from the City of Rapid City and surrounding areas.  The facility is located at 6200 Anderson road five miles East of Rapid City.   Building #8000 houses the facility disinfection equipment.  The building consists of three primary rooms.  The cylinder storage room contains chlorine and sulfur dioxide cylinders plus a chlorine B kit.  The chlorinator room houses the chlorination and dechlorination i 
njectors and pumps.  The laboratory room houses electrical panels and two sets of SCBAs, and an eyewash station. 
The maximum amount of chlorine on site is 6 one ton cylinders.  The maximum amount of sulfur dioxide on site is 4 one ton cylinders. 
The facility is manned from 6:00 to 16:30 on weekdays and from 6:00 to 8:00 on weekends and holidays.  Operators respond to any trouble alarms that may occur. 
Offsite consequence analysis 
Three scenarios are considered for this plan.  One is the worst case scenario for chlorine, and the other two are alternative scenarios, one for chlorine, and one for sulfur dioxide.  The first scenario is defined by EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel... is released as a gas over ten minutes," due to an unspecified failure.  The alternative scenario is defined as "more likely to occur than the worst case scenario. 
The worst-case scenario at the Rapid City Water Reclamation facility inv 
olves a failure of one of the one ton chlorine cylinders.  The offsite consequence analysis was performed utilizing EPA's Off Site Consequence analysis guidance for Chlorine.  Utilizing this document, the worst case analysis scenario determined a toxic end point distance of 2.0 miles. With in this distance a potentially effected residential population of 724 people was obtained. 
Two alternative release scenarios were projected using both the EPA Off Site Consequence Analysis document for Chlorine, and EPA's Risk Management Program guidance for Wastewater treatment plants (For Sulfur Dioxide).  In both scenarios the potential of a sheared off valve was determined to be the greatest risk.  In both cases the end point distance was determined to be 0.3 miles with a potential effected residential population of 3.  
General Release Prevention Program 
The program is based on the following key elements. 
7 Operator training 
7 A comprehensive preventative maintenance program 
7 Use of up to date p 
rocess and safety equipment 
7 Use of written safety procedures 
Accident history 
No accidental releases of chlorine or sulfur dioxide have occurred at this facility in the past five years. 
Emergency Response Program 
The emergency response program has been coordinated with the City of Rapid City Fire Department.  The program contains an emergency response decision tree, and a notification plan.  Emergency operation and response procedures are conducted annually. 
Recommended actions 
Due to the hazardous nature of Chlorine and Sulfur dioxide, the Rapid City Water Reclamation division has implemented best management practices in restricting the amount of chemical on site.  Additionally the division plans to replace the disinfection system with Ultraviolet treatment by the spring of 2001 thus eliminating the hazard entirely.
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