City of California City WWTP - Executive Summary |
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The California City Wastewater Treatment Facility is an extended air, tertiary wastewater treatment plant with a maximum design capability of one million gallons per day and an instantaneous flow of two million gallons per day. The current inflow average is 260,000 gallons per day. Preliminary treatment consists of two submersible chopper pumps in a wet well, an automatic bar screen with washer compactor and flow indicator. The Secondary treatment consists of two aeration basins with surface aerators, two secondary clarifiers with a return activated sludge/waste activated sludge wet well station and chopper pumps. Tertiary treatment consists of a influent filter/pump station, flocculation unit, filters, and a chlorine contact chamber with a 2 hour contact time. The RMP/CalARP regulated portion of the wastewater treatment facility is the chlorine storage, injection system, chlorine scrubber and piping. In principal, the control system monitors flow downstream of the Influent Pump s to correctly meter the injection of chlorine at the in-flow of the Chlorine Contact Tank. Chlorine is stored in 1 Ton D.O.T. cylinders in the Chemical Feed Building. A maximum of two cylinders are connected to the injection system with one cylinder in operation. Chlorine gas is extracted from the cylinders under vacuum by virtue of chlorine vapor pressure and the venturi created by the Chlorine Injection Submersible Pump located at the in-flow of the Chlorine Contact Tank. The City of California City Wastewater Treatment Plant was commissioned in 1993 and the Chlorine Injection System in 1995. The process is regulated by Cal OSHA Process Safety Management of Acutely Hazardous Materials, Title 8 California Code of Regulations 5189 and Title 19 California Code of Regulations 2735 California Accidental Release Prevention Program. This is a RMP/CalARP Program Level 3 facility. The facility has implemented the prevention program described below. The prevention program is based on the requirements of 40 CFR Part 68 and Title 19 CCR 2735 and includes the following: Employee Participation, Process Safety Information, Process Hazard Analysis, Operating Procedures, Training, Contractor Evaluation, Contractors and Visitor Orientation, Pre-Job Start-Up Review, Mechanical Integrity, Code of Safe Work Practices (Hot Work Permit, Control of Hazardous Energy), Management of Change, Incident Investigation, Emergency Planning and Response, and Compliance Audits. Training includes employee responsibilities in the process safety management program, emergency response, hotwork permit procedure, code of safe work practices, and operating procedures. Planned changes to improve safety have been established based on compliance with process safety management audits, every three years, and revalidation of the process hazard analysis, every five years. The facility stores and unloads chlorine. There are 4 - one ton DOT cylinders with a capacity of 2000 pounds each. The tanks a re administratively controlled to hold 95% maximum capacity. Only one tank is operating at any given time; therefore the worst case toxic scenario is based on a 2,000 pound release. The DOT cylinders are stored in a service structure. The City of California City maintains an emergency response plan in compliance with local emergency response agencies. In the event of an accidental release, the facility operators are trained to shut off the source, activate one of the emergency shutdown devices, activate the chlorine scrubber, contact 9-1-1 and secure the area. The chlorine injection system is housed in a secure building with an emergency chlorine scrubber unit in the event of a release. Based on the criteria set forth in 40 CFR 68.10 and 19 CCR 2735.4, this facility has not had an accidental release. This information was verified by the reviewing of records from the Kern County Environmental Health Department - Certified Unified Program Agency. The worst case release scenario is based on the guidance document provided by the Environmental Protection Agency Guidance for Wastewater Treatment Plants. The worst case scenario and alternate release scenario were based on chlorine as the modeled substance. The worst case release of 2,000 pounds of chlorine gas and indicates a 3 ppm end point distance of 2.3 miles. This distance impacts public receptors of an adjacent farm, chemical storage facility and a resident population of 453. The Alternative Release Scenario for this process is a break in chlorine injection transfer connection. This scenario could result in release of 825 pounds of liquids over a ten-minute period. The maximum distance for this scenario is 0.4 miles. The process maintains mitigation measures consisting of relief valves, check valves, manual shutoff valves, startup and operating procedures, grounding equipment, and chlorine scrubber unit. The City of California City has a commitment to employee and public safety. This commitment is demonstrated by the resources invested in accident prevention, such as training personnel and considering safety in design, installation, operation, and maintenance of covered processes. City of California City's policy is to implement reasonable controls to prevent foreseeable releases. However, if a release does occur, trained personnel will respond to control and contain the release. |