Document Edw478qQyedj105KjYZk3d6mb

T-^iPW-- liinniti iiM IHlMfll 10/02/90 iW|HMIMU 15:42 122,:.4 385 9203 G^niultSits | INCORPORATED I i October 2.1990 TR'YITY CONS wm A Mr. Joseph R. Ganc Process Engineer Vista Polymers, Inc. P.0, Box 91 Aberdeen, MS 39730 Dear Mr. Ganc: I am writing to provide you the additional information that you requested in your letter dated 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. 4 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 the 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 configuration:, addition^ 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 previously. Trinity can compare the VCM unit risk factor that Mississippi currently uses with those of other states to determine its appropriateness. However, we have no in-housc expertise to challenge this unit risk factor if it tutus out to be different than that used elsewhere. It is unlikely that Mississippi will overturn this unit risk factor if they have data 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 fencelinc (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 12801N CENTRAL EXPRESSWAY. SUITE 1200, DALLAS, TEXAS US.A. (2h)6Al>KIQQ FAX: (214)3^5-9201 VAB.0001125622 26S193TRNTYUR OTHER OFFICES: AUSTIN. TEXAS. BATON ROUGE. LOUISIANA & OVERLAND PARK. KANSAS 051 'trw'* ........ .... 'si;1 - 10/02/90 IlfWWUffB lliPMIi<WtM 15:43 '-AHi---..... ..................................... ..................... UT.A 385 9203 CONS V* Mr. Ganc - 2 October 2, 2990 r i - U acceptable to Mississippi since their air toxics guidelines arc not expressed that way. In addition, statistical analyses would probably not be useful since they do not fit these guidelines either. I hope that this letter clarifies are capabilities in the areas which you have outlined. I believe that the most efficient thing to do at this point would be to have us perform the initial review of the modeling already performed. We will then be able to better determine if additional modeling is necessary, and give you a cost estimate for what additional work may be done. Please call me at 9214) 661'8100 if you have any additional questions. Sincerely, TRINITY CONSULTANTS. INC. Scott R. Humphrey Project Manager I i i i i i i i i t r i i r ( r 1 VAB.0001125623