Document e5YpyNa5peLaXnxggEQVKwD3e

(conoco) Conoco Chemicals Company Conoco Inc. P. O. Box 91, New Highway 25 Aberdeen, Mississippi 39730 (SOI) 369-6111 December 9, 1983 Mr. Jerry B. Banks, P. E. Mississippi Department of Natural Resources Bureau of Pollution Control P. 0. Box 10385 Jackson, MS 39204 1 * iflfc. Dear Mr. Banks: This letter is to confirm my phone conversation with you on December 6, 1983 in which I reported an incident that occurred in our plant on that day. The old reactor module was down and part of the recovery system was being prepared for maintenance. There was very little VCM in the recovery system. Any liquid VCM that had previously been condensed had been transferred immediately from the recovered VCM collect tank to the recovered VCM receivers by the transfer pump which was operating contin uously. To prepare for the maintenance work, the lines from the recovered VCM collect tank to the recovered VCM receivers were isolated and the transfer pump was shut down. At approximately 7:50 a.m., plant personnel who were working in the area noticed the presence of VCM vapor in the area. They discovered that there was a small amount of liquid coming from the weep hole on the relief valve stack on the recovered VCM collect tank. The system had become full of water and the collect tank was hydrostatically overpressured to 151 PSIG presumably by the high pressure service water system. The relief valve was intermittently opening, relieving small amounts of liquid and then reseating. Plant personnel opened valves on the lines connecting the collect tank to"- the recovered VCM receiver and thq prq^ure. 1>n the collect tank immediately fell. The relief valve, which was set to relieve at 150 PSIG, did not release any more material after this. Plant personnel who observed the discharge said that the time from when the presence of VCM was detected until the situation was corrected was less than 20 minutes. They also noted that when the situation was discovered, small amounts of vapor were observed coming from the relief valve stack. The vapor was not blowing out of the stack but appeared to be weathering or bubbling from liquid in the stack (the stack is 3" pipe about 3 feet long). Later, but before the situation was corrected, liquid which appeared to be water was coming from the stack with no signs of vapor. DTH 000071920 Mr. Jerry B. Banks, P. G. December 9, 1983 Page 2 This discharge is not regulated by the National Emission Standard for Vinyl Chloride (40 CFR, Part 61, Subpart F) because at the time of the discharge the vessel was not in VCM service as defined by the standard. The vessel contained a liquid that was less than 10 weight per cent vinyl chloride. When the discharge valves to the collect tank were closed, the vessel contained only vapor as the vessel was kept empty by the transfer pumps. The total amount of VCM in the collect tank at this time was approximately 27 pounds as shown in the attached calculation. As the vessel was filled with cold water, the VCM condensed until there was no vapor space at the time of the discharge with the vessel at a pressure of 160 PSIG. The vessel contained a maximum of 0.5 weight percent vinyl chloride at the time of the release. This release was reported to the National Response Center under the Costprehensive Environmental Response Compensation and Liability Act of 1980. i By the attached calculation, the maximum amount of VCM that could have been released is 27 pounds. However, it is unlikely that all of this amount was released. By the description given by these observing the release, we believe the amount of the release is approximately 5-10 pounds. If you have any questions, please call me at 601-369-8111, extension 2331 Veldon E. Messick Senior Process Engineer bis be: JF, RAF, DLM, JCL ' r i ptH OOOOT1921