Downers Grove Sanitary District - Executive Summary
Prevention and Emergency Response Policies |
The Downers Grove Sanitary District (DGSD) goal in implementing the Risk Management Program is to reduce employee and public risk of injury or death from an accidental release of chemicals. DGSD is committed to achieving this goal.
Facility and Chemicals Description
DGSD is charged with the responsibility for wastewater collection and treatment services within its jurisdiction. District boundaries currently encompass approximately 20 square miles of DuPage County, Illinois. The District serves the Villages of Downers Grove, Westmont, Oak Brook, Darien, and Woodridge and adjacent, unincorporated areas in DuPage County.
DGSD currently operates one Wastewater Treatment Center (WWTC) treating an average of 11 million gallons per day (mgd) of wastewater and maintaining 232 miles of sanitary sewer lines. The District also provides other programs related to water resources such as industrial pretreatment programs.
The WWTC uses chlorine prima
rily for disinfection, sand filter cleaning, and activated sludge filamentous control. Sulfur dioxide is used at the WWTC for dechlorination.
The DGSD RMP applies to processes involving the use of chlorine and sulfur dioxide. The covered processes at DGSD meet the RMP Program 3 eligibility requirements.
Worst-case Release Scenario
RMP*Comp software was used to determine the worst-case and alternative release scenarios at DGSD. An EPA document, Risk Management Program Guidance for Wastewater Treatment Plants (40 CFR Part 68), was also used.
The worst-case scenario is the failure of one 2,000 lb cylinder of chlorine. Passive mitigation systems have the effect of containing the released gas. Passive mitigation systems at DGSD include the chlorine storage building, and the diked area in the chlorine storage building.
The storage buildings have the effect of containing the released gas. The concrete diked area around the chlorine tank limits the exposed surface area of a pool and
thus reduces the release rate. Since this facility is located in a populated area, the chlorine gas released in this scenario would reach off-site endpoints and nearby public receptors.
At DGSD, the following systems and procedures make a worst-case release unlikely:
7 container inspection upon receipt from chemical supplier,
7 employee training in up-to-date standard operating procedures,
7 standard system inspections (i.e., daily testing of chlorine and sulfur dioxide leak detectors, and
7 emergency response procedures.
Alternative Release Scenarios
For the analysis of the alternative-case scenarios, the largest quantity of chlorine and sulfur dioxide handled on-site in a single vessel at any one time was considered. This quantity is 2000 pounds for either chemical. According to regulations, an alternative release scenario was submitted for both chlorine and sulfur dioxide.
From review of DGSD operations and history, a possible release scenario for chlorine and sulfur dioxide
would be if a valve broke off of a ton cylinder, resulting in a hole in the vapor space of a cylinder. For both chlorine and sulfur dioxide, the chemcials would be released into the respective storage buildings, which mitigate the release. The toxic endpoints for either chemical reach off-site, but do not reach any off-site receptors.
General Prevention Program and Chemical-specific Prevention Steps
-In addition to the EPA's RMP rule, DGSD also complies with OSHA's Process Safety Management Program.
At DGSD, several practices are important to the prevention program. These practices are:
7 Inspection of the chlorine and sulfur dioxide containers upon receipt.
7 Rigorous inspections twice a day of the chlorine and sulfur dioxide cylinder rooms.
7 Daily tests of the chlorine and sulfur dioxide gas detector alarms.
Five-year Accident History
-DGSD has an excellent chemical handling history. In the five years prior to June 21, 1999, no accidental releases from covered processes
have occurred. No deaths, injuries, or property damage have occurred either on or off-site.
Emergency Response Program
The DGSD wastewater treatment facility will rely initially on community emergency responders in the case of an accidental release of chlorine. Employees are also trained to stop small chemical leaks on-site. This training reduces the hazardous effects of minor releases and the potential for minor releases to have off-site effects.
Planned Changes to Improve Safety
An emergency action training program is being developed and implemented at DGSD. The training program for emergency action will provide employees with guidance on what to do in case of a medical, fire, and/or chemical discharge emergency. This plan has been created with the purpose of protecting public health and the environment. DGSD shall use it when training and preparing for a medical, fire, and/or chemical discharge emergency. DGSD shall update this emergency action, training program on an a
nnual basis, as necessary.
Several DGSD employees will be trained on HazMat response. This training will allow DGSD to quickly and safely handle all releases at the WWTC.