Document QgN5rLvKOdkxDOVdMY5JnYz7R
Vista Polymers Inc. A Subsidiary of . Vista Chemical Company
November 18, 1986
Highway 25 Post Office Box 91
Aberdeen, Mississippi 39730 Phone (60?) 369-8111
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Mr. Jerry Banks, P.E. North Air Emissions Section Mississippi Department of Natural Resources Bureau of Pollution Control P. 0. Box 10385 Jackson, MS 39209
Dear Mr * Banks:
In our October 29, 1986 meeting, we discussed an emergency relief valve discharge which occurred June 27, 1986, and a leak which occurred August 8, 1986. This letter provides Information as to why both these instances are not violations of the National Emission Standards for Hazardous Air Pollutants: Vinyl Chloride (NESHAP).
The June 27, 1986 release was from the fresh VCM receiver in reactor module number two. The details of this incident are provided in Mr R. A. Frohreich's letter to you dated July 3, 1986.
In our meeting, you asked us to provide data comparing the frequency of relief valve discharges at our plant compared to that of the PVC industry in general. The EPA conducted a review study of relief valve discharges experienced by PVC plants prior to issuing the proposed rule to the NESHAP on January 9, 1985. The results of this study are summarized in the preamble to the proposed rule beginning on page 1186 of the Wednesday, January 9, 1985, Volume 50 No. 6, Federal Register. A copy of the preamble and the proposed rule are attached.
In the study the EPA first evaluated and then visited five PVC plants which were intended to represent plants with good relief valve discharge records. The preamble states, "In general, the EPAfs evaluation of these plants indicates that each has adopted the combination of equipment, operational procedures, and attitude toward prevention of relief valve discharges intended by the current standard, and that their resulting performance is consistent with compliance with the current standard. The EPAfs evaluation found that a few discharges may continue to occur from some plants that comply with the standard. This observation is consistent with the expectation held by EPA when the standard was written."
VAB.0001115018
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Mr. Jerry Banks 11/18/86 Page 2
In their evaluation study* the EPA separated relief valve discharge
performance data by source (reactor vs. non-reactor) and by resin
type. Based on the performance of the five plants with good relief
valve discharge records* the EPA determined numerical limits to show
compliance with the relief valve discharge standard. The EPA
determined that a suspension PVC resin plant would be in compliance
with the relief valve discharge standard if reactor relief valve
discharges did not exceed 0.035 discharges per 100 batches and if
non-reactor relief valve discharges did not exceed 0.025 discharges
per 100 batches. The performance of our plant since 1980 is shown below:
Frequency
Year
Nmber of Batches
Nunber of Relief Valve Discharges Reactor Non-Reactor
Discharges Per 100 Batches
Reactor Non-Reactor
1980
6540
1
2
0.015
0.030
1981 6527 0 3 0 0.046
1982
7576
1
2
0.013
0.026
1983 8894
2
0
0.022
0
1984
8948
0
00 0
1985 10,213 0 0 0 0
1986(1)
8693
0
_L_ 0
0.012
TOTAL 57,301
4
8
0.007
0.014
This tabulation illustrates the effectiveness of the programs implemented in the plant to prevent relief valve discharges. The one relief valve discharge in the last three years is a very significant reduction from the eight relief valve discharges the three previous years. Our frequency for the total period of 0.007 reactor relief valve discharges per 100 batches is much less than the numerical limit of 0.035 established by the EPA. Also our frequency for the total period of 0.014 non-reactor relief valve discharges per 100 batches is much less than the numerical limit of 0.025 established by the EPA. During the last three years, our frequency for reactor relief valve discharges is zero and for non-reactor relief valve discharges is 0.004. These frequencies are dramatically less than the frequencies established by EPA to demonstrate compliance with the relief valve standard.
A
(1) January 1 to November 1.
VAB.0001115019
Mr. Jerry Banks 11/18/86
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In document EPA-450/3-86-004 (2) on page 2-15, the EPA*s response to
a comment concerning redundant Instrumentation preventative measures was "Generally, at least one level of redundancy for key instrumentation and equipment affecting relief valve discharge incidence is considered by EPA to be necessary for proper operation and maintenance". The June 27 emergency relief valve discharge did occur from a vessel with redundant level instrumentation.
The June 27 emergency relief valve discharge is not a violation of the NESHAP because the plant has taken the following measures to prevent relief valve discharges:
1. Operating Procedures 2. Operator Training 3. Redundant Instrumentation 4. Strong Attitude Towards Preventing Relief Valve Discharges
These are the preventative measures the EPA deems essential to having a good relief valve discharge record. These procedures and attitudes at the plant are very effective in the prevention of relief valve discharges as shown by the historical data presented in the above table. This emergency relief valve discharge does not violate the standard because the plant has taken all appropriate preventative measures and the frequency of relief valve discharges at the plant is much less than the EPA expected for plants to be in compliance when the standard was written.
The leak on August 8, 1986, occurred after charging an experimental batch in reactor 742. The details of this incident are provided in Mr. R. A. Frohreichfs letter to you dated August 14, 1986.
In the September 30, 1986, revisions to the NESHAP a leak is defined as follows:
"Leak"
any of several events that indicate
interruption of confinement of vinyl chloride within
equipment. Leaks include events regulated under
Subpart V of this part such as: (1) An instrument reading
of 10,000 ppm or greater measure according to Method 21
[see Appendix A of 40 CFR Part 60]; (2) indications of
liquid dripping; (3) a sensor detection of failure of a
system, failure of a barrier fluid system, or both;
and (4) detectable emissions as indicated by an instrument
reading of greater than 500 ppm above background for
equipment designated for no detectable emissions measured
according to Test Method 21 [see Appendix A of 40 CFR Part
60]. Leaks also include events regulated under 61.65
(b)(8)(i) for detection of ambient concentrations In
excess of background concentration. A relief valve
discharge is not a leak.
Vinyl Chloride Standards: Responses $o Comments on January 1985 Proposed Revisions, September 1976.
L VAB.0001115020
Mr. Jerry Banks 11/18/86 Page 4
The August event occurred because of the unintentional interruption of confinement of vinyl chloride within process equipment. The leak occurred due to the momentary unexpected opening of the colloid valve on 742 reactor which was immediately closed by the panel operator. The emissions were detected by the fixed point monitoring system portion of the plant's Leak Detection and Elimination Plan. Changes were made to the programmable controls before the next batch was charged to prevent a recurrence of this unusual, unanticipated incident.
This event was a leak and thus not a violation of the NESHAP because:
1. The emissions resulted from the interruption of the confinement of vinyl chloride in process equipment.
2. The emissions were detected by the fixed point monitoring system.
3. Corrective action by the panel operator to stop the leak and the modification to the programmable controller to prevent a recurrence meets the requirements of the Leak Detection Elimination Plan to repair leaks.
Sincerely,
R. A. Frohreich Director of Environmental Control
rah
attachment
cc: JF, JWW, VEM, WLM, JCL, H. J. Neeld
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VAB.0001115021
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