San Miguel Electric Cooperative, Inc. - Executive Summary

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San Miguel Electric Cooperative, Inc. (San Miguel) was created on February 17, 1977 under the Rural Electric Cooperative Act of the State of Texas, for the purpose of owning and operating a 400 MW mine-mouth, lignite-fired generating plant and associated mining facilities which furnish power and energy to Brazos Electric Power Cooperative, Inc. (Brazos), and South Texas Electric Cooperative, Inc. (STEC). 
Brazos and STEC initiated construction of the plant as a joint venture in 1974. San Miguel purchased the plant and related mining facilities upon receiving long-term financing in 1978. Commercial operation of the plant began on January 7, 1982. 
The generating plant is located in a rural area approximately six miles southeast of Christine, Texas in Atascosa County. The plant is fueled with lignite, which is mined from deposits in Atascosa and McMullen Counties. 
The cooling system for the power station's turbine-generator and it 
s auxiliaries utilizes a single mechanical draft cooling tower. The tower is constructed of wood and has eighteen cells. Biological fouling in the open recirculating, heat transfer system can be caused by excessive growth and development of algae, fungi, and bacteria. These types of biological deposits can severely reduce heat transfer efficiency if not controlled. Chlorine (Cl2), an oxidizing biocide is utilized to control the biological growth in the tower and associated heat exchangers. Chlorine is fed through a distribution header into the cooling tower basin at approximately 10.5 lbs./hour.   
San Miguel keeps five each one ton cylinders of chlorine on hand. The cylinders are kept on a storage rack located outside of the chlorine feed building. Only one cylinder is in service at a time. A new shipment of chlorine is ordered when the last cylinder is put into service.  
The chlorine feed building is equipped with a chlorine gas monitor that will alarm the 24 hour per day staffed co 
ntrol rooms in the event of a chlorine leak. In the event of an alarm, lab personnel are contacted and are responsible for evaluating the severity of the leak and securing the area. A leak that occurs beyond the chlorine cylinder will be isolated by closing the valve on the cylinder that is in service. The maximum quantity of chlorine released in the above scenario is in section 3 of the RMP, and is calculated to be 317 pounds. There would be no off-site impacts due to the 0.56 mile distance to endpoint. Modeling was obtained from the EPA's RMP Guidance For Waste Water Treatment Plants Reference Tables Or Equations. 
The worst case release scenario modeling, also obtained from EPA's RMP Guidance For Waste Water Treatment Plants Reference Tables Or Equations, is calculated releasing the total quantity of the cylinder, 2,000 lbs. within a ten minute period. The distance to endpoint in the worst-case release is three (3) miles. There is one residence within the three-mile radius of t 
he cylinder storage area. Atascosa County's Emergency Management Coordinator will be contacted in the event of a worst case release. 
There have been no chlorine releases within the last five years.
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