City of Bunkie Waste Water Treatment Plant - Executive Summary
Executive Summary |
LADEQ Facility ID Number 19907. This Risk Management Plan has been developed for The City of Bunkie Waste Water Treatment Plant in accordance with 40 CFR part 68. This facility is subject to the requirements of this program due to the usage and storage of chlorine in an amount greater than 2,500 lbs.
The facility is located within the city limits of Bunkie, LA on the corner of E. Oak St. and Frazier Rd. The area surrounding the plant is mostly farmland with a residential area to the southwest. The latitude and longitude of the facility was obtained using a hand-held Garmin 75 GPS device with an accuracy of +/- 100 meters. The facility is easily visible on the USGS quadrangle map entitled Bunkie, LA.
The facility treats waste water from residential and commercial entities within in Bunkie, LA. This treatment includes the chlorination of the waste water prior to being discharged. A continuous rate of chlorine is mixed with water in the injection room. Once t
he chlorine is injected into the water it is diluted to an amount which is less than 1% chlorine by weight. Therefore, the process that is subject to the RMP requirements begins with the chlorine supply (3-1 ton cylinders) and ends at the point of injection with the water. The facility purchases the pre-filled chlorine cylinders from Harcros Chemicals, Inc. approximately once every 25 days. The waste water plant stores a maximum of three-one ton cylinders (6,000 lbs.) at any one time. The tanks are within a metal shed that is open on the east and south sides.
The worst-case release scenario would involve the release of the greatest amount from a single vessel as required by 40 CFR part 68.25 (b)-Determination of worst-case release quantity. This type of release may occur as a result of catastrophic natural or other unforeseen disaster. A release of 2,000 lbs. for a duration of 10 minutes results in a 1.3 mile distance to the toxic endpoint. This endpoint is the location where m
inimal effects of exposure to the toxic substance are likely to occur as determined by the American Industrial Hygiene Association. This distance encompasses a majority of the city of Bunkie from Bayou Dulac Rd. to US Hwy 71 at Bayou Huffpower and from Hwy. 29 E. 115 at Tanner Lake to Shirley Rd. (Hwy 1177) at Sweet Briar Dr. According to a January 1999 publication of July 1, 1998 population estimates the population of Bunkie is approximately 5,075.
An alternative case or a more likely release of chlorine could occur as a result of a valve, regulator seal, or gasket leak, or from a small amount of liquefied chlorine being trapped between the valve of the cylinder and the equipment line attachment. The plant is equipped with a leak detection system with sensors located near the chlorine cylinders and in the injection room. If a 1 ppm leak is detected an alarm will sound and an automatic call to the plant operator and the Bunkie Fire Department is made. The injection system is als
o equipped with a device that automatically closes the valves at the cylinders if a loss in pressure within the injection line is detected. According to facility personnel, it would take less than 1 minute to respond by closing the flow valve and thus stopping the leak if employees are on-site at the time of the leak detection. The plant is manned an average of 12 hrs. per day. If the alarm sounds at a time when no personnel are on-site, it would take approximately 15 minutes for personnel to arrive on-site and stop the leak. Assuming the chlorine flashes to the atmosphere at a rate of 0.5 ft3/min (1.5 lbs. of chlorine) for a maximum of 15 minutes the distance to the toxic endpoint is less than 0.1 mile. The area within 0.1 mile of the facility extends along E. Oak St. from Cottonwood St. to 0.1 mile north of the plant and from Cottonwood St and Frazier to Gum St. and Balsa St. Based on a maximum population density of 8,268 p/mi2, the population within 0.1 mile of the facility i
s approximately 65. However, based on information obtained from USGS topographic map of Bunkie, LA and knowledge of the surrounding area the actual population within the alternative-case release circle is approximately 30. This type of release is expected to impact only those persons in the immediate vicinity of the chlorine cylinders. There are no environmental receptors within this area.
The facility has not experienced a release which caused on or off site injury, death or property damage within the past five years.
Facility employees are properly trained in the operating and maintenance procedures. These procedures are kept on-site in the O & M Manuals developed by Domingue-Szabo & Associates, Inc. Records of inspections, testing, and maintenance are also kept on file at the facility. In addition to the leak detection system the process is also equipped with an automatic shut-off system. If a change in pressure within the injection line is detected the system automatica
lly closes the flow valve at the chlorine tank.
Written emergency response procedures are kept on file at the facility. The emergency response procedures describe actions for incidental response for facility personnel in the event of a relatively small leak or release that does not pose an immediate safety or health hazard. If incidental response activities do not halt the release or the release poses an immediate safety or health hazard, specially trained response personnel are contacted to take over response activities. In the event of a chlorine leak or release, employees are instructed to asses the situation and to determine if it is safe to discontinue the leak without the help of emergency responders. If there are any doubts as to the safety of the release, the employees are to initiate the written notification procedures.
Current safety features at the facility include a leak detection system which activates the phone notification system and an automatic shut-off feature.
Inspections of the process and associated equipment are conducted on a regular basis to avoid failure and detect normal wear and tear of equipment parts. Also, the metal shed protects the chlorine cylinders from the heating effects of direct sunlight.