City of Altamonte Springs Regional WRF - Executive Summary
FACILITY DESCRIPTION |
The City of Altamonte Springs operates a regional wastewater treatment plant located in the southern part of the City, just north of the Orange County border. The function of this plant is to treat sewage. Through the use of screening, primary clarification, nitrification, secondary clarification, filtration, and disinfection, domestic and commercial wastewaters are treated for reuse and, with dechlorination, are acceptable for release to the river.
Chlorine gas, a hazardous and toxic chemical, is used for disinfection because it provides the best balance of disinfection ability, ease of use, relatively low cost, and residual disinfecting power for the water treated and public served. Typically, the City will store up to 8,000 pounds of chlorine at the plant for current and future use.
Sulfur Dioxide, a hazardous and toxic chemical, is utilized to remove excessive residual chlorine from the treatment plant effluent when the plant is discharging to the Little Wek
iva River (periodically during year).
The City has used chlorine in the treatment process since the inception of the plant, and sulfur dioxide since the late 1980s.
The entire plant grounds are maintained 24 hours per day by a trained, licensed staff. The plant perimeter is protected against intrusion by a perimeter fence. Chlorine is stored and used in a specialized storage area at the southeast portion of the plant. The area is protected by a gas detection system and is secured against intrusion. Sulfur dioxide is stored and used in a sealed room near the center of the facility and is secured against intrusion.
ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES:
The City's overall policy with respect to chlorine and sulfur dioxide gas is based around the need for conscientious storage, handling, and use of the chemical. The City has a comprehensive program of procedures related to these chemicals designed to minimize the likelihood of exposure to our employees as well
as the residents. Procedures in place for the Wastewater Treatment Plant mandate the use of a specialized team of employees who are the only persons allowed to handle the containers or equipment.
The procedures are based, in part, on the most stringent requirements of the OSHA Process Safety Management rule.
Emergency response, in the event of a release, is handled through a formal Emergency Response Plan enacted by the City several years ago. The City of Altamonte Springs Fire Department serves as the initial responder in the case of all emergency calls from a Utility facility, including the wastewater plant. In the event that a hazardous release has occurred, the Fire Department will mobilize the Seminole County Hazardous Materials (HAZMAT) response unit. The County HAZMAT team will perform coordination of response, public communication, recovery and cleanup activities.
CHEMICAL RELEASE SCENARIOS:
As part of the procedure to prepare this Risk Management Plan (RMP), the City has un
dertaken a rigorous review of the required worst-case and alternate release scenarios for chlorine and sulfur dioxide at the wastewater plant. These scenarios are reviewed to determine the offsite impact, if any, of such a release.
The "worst-case" scenario involves the loss of all the contents of the largest chemical container (a one-ton container of chlorine or 900 pound rack of sulfur dioxide cylinders), which are the largest single storage unit held by the City. Under regulatory requirements, this scenario assumes that the worst possible combination of release rate, weather conditions, and release location occur. If a release were to occur in this "worst-case" mode, an area outside the plant site would be affected.
The City believes that the risk associated with such a scenario is negligible, since the conditions leading to this type of release are considered to be extremely rare. The City, as part of its Accident Prevention Program, requires that the persons delivering chlorine
or sulfur dioxide to the wastewater plant be trained in the safe handling of containers and cylinders. The chemical producers, through their professional trade associations, have developed packaging, inspection, and transportation standards designed to maximize the safe handling of chlorine and sulfur dioxide in public areas.
The most likely form of release involves a container leak as a result of a severely corroded container or a faulty supply valve. Chemical industry standards provide protection against corroded containers and it is the City's policy to reject any container or cylinder exhibiting traits of a defective valve. The City's procedures mandate that the connection of containers or cylinders be performed only during daylight hours with a specifically-trained staff providing the service. In the event of a leak, the gas concentration detectors would sound an alarm. The alarm, in turn, will activate the City's emergency response protocols.
The City considered an alternate re
lease scenario for this RMP. The alternate release scenario assumes that a lesser amount of gas is released than during the worst-case scenarios. Under these alternates, a relatively small amount of gas would escape leading to a small area of offsite impact.
FIVE-YEAR ACCIDENT HISTORY:
Over the last five years, the City of Altamonte Springs has not experienced an accidental release of chlorine or sulfur dioxide.
ACCIDENTAL RELEASE PREVENTION PROGRAM:
As mentioned earlier, the City has implemented a strict level of safety procedures and policies, as required by state and federal rules. Specifically, the City is implementing a program designed to minimize the likelihood, and potential impact, of accidental releases. Specific elements of the program include regular process hazard analysis, training, contractor safety programs, regular review and updating of operating procedures, maintenance programs to enhance mechanical integrity, self-administered compliance reviews, and management
Each of the individual elements is supported by an organization framework in which key employees are given responsibility for RMP elements. This management program includes mandatory review and documentation procedures to ensure future safety as the plants and processes change.