Treschwig Central Wastewater Treatment Plant - Executive Summary
The Treschwig Central Wastewater Treatment Plant (WWTP) is a publicly owned wastewater treatment facility in north Harris County. The facility serves Tattor Road Municipal Utility District, Harris County Municipal Utility District No. 43, Harris county Water Control & Improvement District No. 136, Postwood Municipal Utility District and Aldine Independent School District. Each of these entities participates in the Treschwig Joint Powers Board, which has authority to make all policy and procedural decisions for the facility. A contract operations company operates the facility. |
Treschwig Central WWTP utilizes two toxic chemicals, chlorine and sulfur dioxide, to disinfect treated plant effluent. Chlorine and sulfur dioxide are stored on site in 2,000-pound steel cylinders. The chemical feed equipment is used to measure and apply the chemicals to the treated effluent for disinfection. There are no administrative controls or active mitigation systems in place at Treschwig Central WWT
P that would affect consideration of the release scenarios discussed below.
As part of the Risk Management Program, Treschwig Central WWTP has established a prevention program to identify potential hazards and implement operational and maintenance procedures to reduce the risk of an accidental release. The facilities used at Treschwig Central WWTP are designed and constructed in accordance with applicable ANSI, ASTM, and ASME standards. The prevention program includes annual hazard reviews, on-going safety training for personnel, daily equipment inspection and annual preventative maintenance. A system has been established to investigate any hazardous incident related to the chemical storage and feed system. Treschwig Central WWTP has also established a compliance audit team to review the on-going prevention program and update the program as necessary to provide continued protection to the facility employees and the surrounding community.
The Treschwig Central WWTP has not had any
accidental releases of a regulated toxic substance that caused any on-site or offsite effects within the past five years.
As part of the Risk Management Program, Treschwig Central WWTP has developed three scenarios to evaluate the possible effects of an accidental release and assist emergency personnel to respond appropriately. The "worst-case scenario" and the two "alternative release scenarios" were developed using the EPA's "RMP Guidance for Wastewater Treatment Plants."
The worst-case scenario for the facility is based on the release of an entire 2,000-pound cylinder of chlorine over a period of 10 minutes. This scenario could have hazardous effects up to 1.3 miles downwind of the vessel. Within 1.3 miles of the facility, there are homes, schools, businesses, recreation areas and day care centers that could be affected by the worst-case release.
The alternative scenario for a chlorine release is based on a 1/2-inch diameter vandalistic gun shot to a chlorine storage vessel.
This scenario could have hazardous effects up to 0.4 miles downwind of the vessel. The alternative sulfur dioxide release is based on the failure of a 1/2-inch diameter pressure valve on a sulfur dioxide storage vessel. This scenario could also have hazardous effects up to 0.4 miles downwind of the release point.
The Spring Volunteer Fire Department (VFD) is the local emergency responder responsible for handling an accidental chemical release at Treschwig Central WWTP. The emergency contact number for this agency is 911. Treschwig Central WWTP has coordinated and provided a copy of the Risk Management Program for the facility to the Spring VFD and the Harris County Local Emergency Planning Committee (LEPC) for Unincorporated Areas.