Document JvvZ4DaV7V3NXZeeXoJkaoQge

t A INCORPORATED October 2,1990 Mr. Joseph R. Ganc Process Engineer Vista Polymers, Inc. P.O. Box 91 Aberdeen, MS 39730 Dear Mr. Ganc: I am writing to provide you the additional information that you requested in your letter September 28,1990 concerning Trinity's air quality capabilities. Specifically, you asked for clarification concerning Trinity's ability to assist you in three areas related to the VCM cancer risk modeling analysis that you recently had performed for your facility. These three areas are addressed below. MODELING ASSESSMENT As indicated in my letter dated September 17,1990, Trinity can review the modeling that has already been performed for your facility. This review will verify die appropriateness of the dispersion model used, the meteorological data, and the modeling procedures. After this is done, we can make suggestions as to what can be done to reduce the calculated concentrations. A simple review of the modeling should take no more than 16 hours of labor. However, if it is determined that additional modeling must be performed to evaluate alternate configurations, additional costs would be incurred. As a rough estimate of what costs might be incurred to remodel the situation, a complete modeling analysis using 5 years of meteorological data usually costs between $5,000 and $8,000 to complete. TOXICITY ASSESSMENT As stated previously. Trinity can compare the VCM unit risk factor that Mississippi currently uses with those of other stales to determine its appropriateness. However, we have no in-house expertise to challenge this unit risk factor if it turns out to be different than that used elsewhere. It is unlikely that Mississippi will overturn this unit risk factor if they have drta that supports it unless you are able to provide strong evidence that it is incorrect. RISK ASSESSMENT As we have discussed, it may be appropriate to calculate the cancer risk at areas beyond the fenceline (i.e. at the nearest residence) to arrive at a more representative idea of the actual cancer risk. This would require additional modeling such as that discussed above. However, calculating the cancer risk at population centroids to determine cumulative cancer risk probably would not be 12801 N. CENTRAL EXPRESSWAY, SUITE 1200, DALLAS, TEXAS 75243 U.S.A. (214)661-8100 * FAX: (214)385-9203 TELEX: 265193 TRNTY UR * OTHER OFFICES: AUSTIN, TEXAS, RATON ROUGE, LOUISIANA & OVERLAND PARK, KANSAS VAB.0001125630