Overholser Water Treatment Plant - Executive Summary |
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The Overholser Water Treatment Plant (OWTP) has adopted this Program 3 Risk Management Plan (RMP) in order to comply with federal requirements in 40 C.F.R. 68 regulating risk management of highly hazardous chemicals. This plan will help prevent the occurrence of, or minimize the consequences of, catastrophic releases by stating policies and procedures for the management of process hazards in start-up, operation, inspection, maintenance, and the other matters addressed in the federal standard. The OWTP plan calls for employee participation and includes all the elements of the employee participation provisions of the standard. At a minimum, OWTP employees will: (1) participate in the development and implementation of the site specific Process Safety Management (PSM) and RMP programs; (2) participate in conducting the chlorine and ammonia process hazard analysis; (3) be trained annually on the PSM and RMP programs and made aware of any interim changes to the program or process systems; (4) work with management to develop additional programs or procedures relative to chlorine and ammonia process safety; and, (5) participate in periodic audits of the chemical processes and the PSM Program. Accidental Release Prevention and Emergency Response Policies Preventative maintenance is the key to minimizing the potential for accidental releases. Standard Operating Procedures (SOPs) have been reviewed and revised, as necessary, to enable the employees to perform their work in a safe and efficient manner. The OWTP has chosen to be a non-responding facility in the event of an emergency. Responsibility for emergency response to an accidental release has been given to the Oklahoma City Police and Fire Departments and the State and Local Emergency Planning Committees. Stationary Sources and Regulated Substances. The OWTP utilizes chlorine and ammonia for disinfection of treated water. The maximum inventory and threshold quantities for these chemicals are shown below. Chem ical Maximum Inventory (lb.) Threshold Quantity (lb.) Chlorine 22,800 2,500 Ammonia 24,000 10,000 The threshold quantity for ammonia is above the maximum inventory for the OWTP. OWTP is therefore not subject to the RMP requirements for ammonia other than those in the General Duty Clause. These requirements are 1) to inform and coordinate with local emergency responders about the presence of the substance on site and to provide a safe environment through adequate process safety. The OWTP meets those requirements for ammonia. An alternative case scenario model was run in case future on site maximum inventory exceeds the regulatory threshold ceiling. Worst-Case and Alternative Release Scenarios The Offsite Consequence Analysis (OCA) evaluated a worst-case release and an alternative release scenario. A dense gas dispersion model (SLAB) was used to determine endpoint distances for both scenarios. The model input parameters and assumptions fulfilled 40 CFR Part 68 requirements and are summarized in the following table SLAB Input Parameters Worst-Case Scenario Alternative Scenario Chlorine / Ammonia End Point Concentration (mg/l) 0.0087 0.0087 / 0.14 Windspeed (m/s) 1.5 3.0 Atmospheric Stability Class F D Temperature (0 F) 77 77 Humidity (%) 50 50 Height of Release (m) 0.00 0.01 Surface Roughness (m) 0.02 0.09 Impact Radius (miles) 6.2 0.40 / 0.43 Affected Population (persons) 247,000 1436 / 1660 The results of the air dispersion model are summarized in the table along with estimated populations within the impact areas. The population data was estimated using the Land-view block uniform density group method. The OWTP is located in a predominantly urbanized area and no environmental receptors such as national and state parks, forests, monuments, wildlife preserves or wilderness areas were identified within the radius of impact for either scenario. General Accidental Release Prevention Program The OWTP has acquired knowledge regarding process safety and hazard assessment. Under Program 3, OWTP has used this information to implement policies and procedures related to operations, training, mechanical integrity, incident investigations, compliance audits, management of change, pre-start review, contractors, employee participation, and hot work permits in order to create a safe workplace . Chemical - Specific Prevention Steps The completion of the Hazard Assessment resulted in the recognition of preventive steps to eliminate or minimize the possibility for accidental releases and employee exposure to chemical risk. Process Safety Management Program OWTP has compiled a Process Safety Management program to minimize releases. This Program includes safety information related to the covered chemicals, hazard review, operating and maintenance schedules, training, compliance audits, incident investigations, and emergency response procedures. Five-year Accident History In the last 5 years, there have not been any accidental releases from the chemical processes that resulted in deaths, injuries, evacuations, sheltering-in-place, property damage, or environmental damage. |