City of Piqua Wastewater Plant - Executive Summary |
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Exective Summary for The City of Piqua Wastewater Plant The Piqua Waste Water Treatment Plant is a 4.5 MGD activated sludge treatment facility which operates as a department under the jusisdiction of the City of Piqua. The plant is located on the east side of the Miami River. As a city department, the Wastewater Treatment Plant is part of the city's Emergecy Preparedness Plan. This plan which was written in 1985 and upgraded in 1988 is a comprehensive document which outlines the City's role and procedures for handling all levels of emergencies that might impact residence of the City or surrounding communities. Presently this Emergency Preparedeness Plan is in the process of being updated. Section 15 of the city's Emergency Response Plan contains the individual unit plans for the departments within the City of Piqua. Specifically, Section 15.05C deals with Emergency Operation Plan for the Wastwater Plant which operates as a subunit of the Department of Public Works. As stated in the City's Emergency Preparedness Plan, up to 4 one ton cylnders of chlorine may be stored on site at any given time but only one cylinder is actually in use at any given time. The physical state of the chorine can best be described as chlorine gas liquefied by pressure. TOXIC WORST POSSIBLE SCENARIO In the development of the worst possible scenario accident it is assumed that a 2000 pound tank of chlorine would rupture and discharge the total contents to atmosphere. Although the likelihood of this occuring would be unlikely, it is possible that a structural failure of the tank itself could possibly cause and event like this to occur. Of course, there is even the more remote possibility that a natural disaster such as a tornado could cause all of the tanks of chlorine that are in storage to be destroyed thus the potential for a release of up to 8000 pounds could be possible. However, the worst possible scenario for the purposes of this document is to be calculated on a releas e of the largest container of the hazardous material on site, thus a release of only 2000 pounds was used. TOXIC ALTERNATE SCENARIO In the development of an alternate scenario it is assumed that the most likely event that would occur would involve an operator error in which case the discharge of chlorine gas would occur through a 5/16 inch line located at the top of the tank. In fact, experience has show us that in the accident of 6-20-98 this was the case and the discharge that resulted was in the form of chlorine gas. The calculaions for the Toxic Alternate Release Scenario was based on this type of failure. RMP Comp was used to calculate the endpoints for both this and the Toxic Worst Case. The Piqua Waste Water Treatment Facility is located in an Urban Area in the City of Piqua, Ohio. Many Trees, residences and businesses fall well with a 1/2 mile radius of the facility. During the normal operation hours of 7am to 3pm monday thru friday the facillity is fully staffed. Howev er, during the following hours only one empoyee is on duty: 3pm to 11pm seven days a week, 11pm to 7 am seven days per week, 7am to 3pm on Sunday. Two operators are on duty on Saturday 7am to 3pm. DESCRIPTION OF EMERGENCY PROCEDURES EMERGENCY EQUIPMENT ON HAND Dynamation Combo Gas Detectors (2) 1 in office, 1 in vehicle S-10 Bio-Pac 30 Self Contained Breathing Apparatus (1) Hallway east of lunchroom Emergency Life Supporting System (ELSA) 5 minute Vehicle S-10 breathing apparatus Chlorine Emergency Kit "B" for Ton Cylinders (1) Garage Workshop Area Torso Safety Harness (2) 1 Vehicle S-10 1 Vehicle S-19 Fresh Air Blower (1) Garage Workshop Area Motorola Portable Radios (2) 1 Lunchroom 1 Office 3 inch Trailer Mounted Trash Pump* Blower Room 2 inch Portable Pump* Garage Workshop Area *Hoses for pumps are located in blower intake room The Emergency Perparedness Plan for the City of Piqua outlines the procedure to be used in the event of a chlorine leak at the Piqua Wastewater Treatment Plant. This procedure cn be found in Sectin 15.05c-13 of the plan and reads as follows: CHLORINE LEAK All operators are instructed not to change chlorine cylinders alone. They are trained in detecting small leaks that may occur during a routi ne cylinder change. In the event of a major leak (i.e. ruptured line, cylinder, or broken valve) the following procedures should be followed: 1. Evacuate Chlorine Building area Immediately. Stay upwind. 2. Contact Fire Department (2011) 3. DO NOT attempt to repair the leak alone. 4. A "Chlorine Emergency Kit B for ton cylinders is located in the Piqua Fire Department. 5. Depending on wind velocity and direction certain areas around the plant may need to be evacuated. In addition to the above procedures it is understood that the OHIO EPA would be notified in the event of a major release of contaminants to the air, land, or water. 5 YEAR ACCIDENT HISTORY DESCRIPTION On June 20, 1998 at 2:00 pm while changing a chlorine gas cylinder a leak occured with 80 pounds left on the scale. The builiding was immediatley evacuated and the local fire department was called. The fire department was already suited-up when they arrived and they entered the chlorine room and shut off the v alve stopping the leak. After the incident the reading on the scale was 20 pounds. Consequently, the leak discharged approximately 60 pounds of chlorine gas to atmosphere. |