Wastewater Treatment Plant, Newberg, Oregon - Executive Summary
The City of Newberg is committed to employee safety and health, and the safety and health of the public and the environment. By preparing this Wastewater Treatment Plant Risk Management Plan, the City is continuing its historical and ongoing program to reduce the risk from chlorine use at the facility. |
Risk management planning begins with a strong safety program to prevent or minimize the potential for accidents at the plant. The City's Safety Manual details the safety training, chlorine handling procedures and other accident prevention methods used at the plant. As a result of routine application of this program, the plant has an excellent safety record. In 13 years of operation it has never experienced a chlorine incident.
Chlorine is primarily used to disinfect wastewater at the treatment plant. Chlorine is delivered and stored under pressure in specially manufactured, welded steel cylinders. Each cylinder contains 2000 pounds of chlorine. After delivery, cylinders
are stored on special supports inside a room specifically designed for this purpose. Depending on the amount needed at the plant, up to four cylinders may be stored, plus one in use, at any time.
Chlorine gas contained in these cylinders is transferred to metering equipment where it is dissolved in water. Chlorine in solution is then transferred to points in the treatment plant where it is applied to wastewater for disinfection and other purposes. There is an important safety feature of the equipment used at the treatment plant; namely, chlorine gas is drawn into solution by vacuum, rather than being forced by pressure. As a result, the system will shut down in the event of a chlorine leak.
In preparing the RMP, the City performed an assessment of the potential offsite effects of an accidental release of chlorine at the plant. For planning purposes two release scenarios were evaluated. The worst case scenario is intended to estimate the maximum possible distance
from the treatment plant that chlorine could travel under the worst combination of circumstances. An alternative, more reasonable scenario is also presented.
Under the worst case scenario, it is assumed that a full chlorine cylinder is dropped while being unloaded at the plant's receiving area. As a result, it ruptures and releases its contents to the atmosphere. For this circumstance the estimated distance that chlorine could potentially travel is 1.3 miles from the plant site. Depending on wind direction, this 1.3 miles could be in any direction.
A written protocol is rigorously followed during chlorine deliveries to prevent such an accident from occurring. Nevertheless, for the conditions of the worst case incident, potential off site effects include an area with 4,703 residents, one school, four city parks, 1 hospital and the Smurfit Plant.
A more reasonable scenario assumes that a valve on one of the chlorine cylinders stored in the chlorine room breaks. As a result, chlorin
e gas leaks through the broken valve into the room. In this case, the valve opening and building enclosure retard release to the outside air and reduce the offsite distance that chlorine could potentially travel to 0.1 mile. Again, depending on wind direction, this 0.1 mile could be in any direction. For conditions of the alternative scenario, potential offsite effects include an area with three residents.
Accident Prevention Practices
Many accident prevention practices are in place at the treatment plant, including those specified by Occupational Safety and Health Administration (OSHA) in its Process Safety Management (PSM) standard. Key prevention practices include written protocols which plant personnel rigorously follow when chlorine is delivered to the plant site and when cylinders are connected to metering equipment. Routine inspection and maintenance protocols are also followed to ensure the integrity of the entire chlorine system. A leak detector is provided inside the plant'
s chlorine storage room. Specialized training related to safe handling of chlorine is provided to operators of the chlorine system, and training is verified and documented as part of the accident prevention program.
Emergency Response Plan
The treatment plant's emergency action plan is integrated with the City's community-wide Emergency Operations Plan (EOP). The EOP covers a wide range of potential emergency situations. It identifies the succession of authority, command structure, and evacuation and other procedures to be followed during an emergency.
In the event of a chlorine accident at the plant, plant personnel will immediately call 911 to notify the Fire Department and Police Department. The Fire Department will then contact the hospital and the Safety Director at the Smurfit plant. The Fire Department will request aid from the Tualatin Valley Fire and Rescue Hazardous Materials Response Team to respond to the chlorine release. The Police Chief will provide overall Incide
nt Command during the emergency, and as such will receive full cooperation from all other city departments.
All plant personnel, visitors and contractors will evacuate the treatment plant immediately upon notification of the accident and assemble at a point off the plant site near the entrance gate and upwind of the accident location. Each individual should report to the plant's Emergency Response Coordinator (Operations Supervisor, Utilities Division) who is responsible for accounting for all individuals on site. Individuals are to remain at the assembly location to await further instructions.