Harris County WCID #84 - Executive Summary

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The Harris County WCID #84 owns and operates a municipal waste water treatment plant in the Channelview area. This waste water treatment plant is responsible for the treatment of the sanitary waste from several surrounding subdivisions, households and small local businesses.  Harris County WCID #84 contracts the operation of this waste water treatment plant to Muniservice Corporation.  Both Harris County WCID #84 and Muniservice are committed to the safe operation of the waste water treatment plant.  The waste water plant utilizes two substances that are listed on the Environmental Protection Agencies (EPA) hazardous substances list.  These two substances are chlorine and sulfur dioxide.  The chlorine is stored in individual one ton cylinders, and no more than two are ever stored on site at one time.  The chlorine is used to disinfect the waste water prior to release from the treatment plant.  Sulfur dioxide is stored in 150 pound cylinders and no more than ten are stored on site at on 
etime.  The sulfur dioxide is used to dechlorinate the water prior to release from the treatment plant.   While the quantity of sulfur dioxide is below the threshold  levels, it has been included in this plan pro-actively.  As a part of the Risk Management Plan, both a worst case and alternative release scenarios were modeled using an EPA developed and approved dispersion modeling program.  The worst case release scenarios are complete loss of inventory in a ten minute period.  The consequences of such a release would result in offsite impacts for chlorine of 1.9 mile from the facility.  Several households, a school and Cullen Park could be impacted.  The worst case release scenario for sulfur dioxide would result in a 1.1 mile impact from the facility. Several households could be effected.  Leaking valve and rupture disk are typical alternative release scenarios.  The offsite impact for these releases are for chlorine at 0.2 mile and for sulfur dioxide at 0.1 mile from the facility.   
Both these scenarios result in minimal offsite consequences and could effect only a few households close to the facility.  Regardless of the type of release, the treatment plant is equipped with monitors to detect both chlorine and sulfur dioxide.  These monitors sound locally on the plant, and automatically notify the plant manager and operator 24 hours a day of the specifics of a release so that the proper action may be taken.  The facility has had no history of releases of either chlorine or sulfur dioxide.  Harris County WCID #84 has coordinated with local emergency response facilities and fire departments to ensure that in the event of an accidental release, that qualified and trained individuals will respond quickly to minimize offsite impacts.  Both Harris County WCID #84 and Muniservice are committed to the ongoing safe operation and handling of hazardous substances and equipment that are necessary in order to provide the service to the community.
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