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Home My WebLink AboutDSHW-2009-008967 - 0901a0688013be1fATK ALLIANT TECHSYSTEMS ATK Thiokol Inc. P.O. Box 707 Brigham City, UT 84302-0707 Tel 435 863-3511 Fax 435 863-2234 13 December 2005 8200-FY06-033 Mr. Dennis R. Downs, Executive Secretary State of Utah Department of Environmental Quality Division of Solid and Hazardous Waste 288 N. 1460 W. P.O. Box 144880 Salt Lake City, Utah 84114-4880 HAND DELIVERED DEC 1 ^1-2005 UTAH DIVISIOROF SOLID & HAZARDOUS WASTE Dear Mr. Downs ATTENTION: Jeff Vandel Subject: Revised report: Results of Post-Excavation Sampling at M-39 and M636, incorporating comments from UDSHW dated September 13, 2005. ATK Thiokol - Promontory Facility, EPA ID #009081357 In a September 13,2005 letter, your office sent comments regarding the ATK Promontory report entitled "Results of Post-Excavation Sampling at M-39 andM636". These comments have been incorporated in the attached revised version of the report. Please find two copies of the report as well as a list of the Division's comments and responses from ATK. If you have any questions regarding these responses, please direct them to myself at (435) 863- 3344. Sincerely Paul V Hancock, Manager Environmental Remediation RESPONSE TO STATE COMMENTS DATED SEPTEMBER 13,2005: RESULTS OF POST-EXCAVATION SAMPLING AT M-39 AND M.636 1. Comment: The text reports a value of 4,900 mg/kg as the industrial preliminary risk goal (PRG) for silver, but the EPA Region 9 value is 5,100 mg/kg. Please clarify. Response: The value of 4,900 mg/kg was presented in the risk assessment that was part of the 2003 Sampling and Analysis Plan. This is clarified in Section 2.2 of the revised report. 2. Comment: Please modify the second paragraph on page 1 and indicate that the Division recommended additional sampling to determine if the site met the requirements of R315- 101, and that Thiokol agreed with this recommendation and submitted a sampling plan. Response: The second paragraph of page I has been accordingly modified. 3. Comment: Please modify the third paragraph on page 1 and indicate that this document has three purposes; 1) presenting the results of a nature and extent investigation, 2) human health and ecological risk assessment and 3) that an evaluation of the potential for migration of metals contamination from soil to groundwater was presented in the USU study. Response: The third paragraph of page I has been accordingly modified. 4. Comment: Perchlorate sampling is not acknowledged in the field notes in Appendix B, but it is noted that the data in Appendix A show that all samples were collected on the same day. Please provide copies of the chain-of-custody forms used as part of this project. Response: Chain ofcustody forms associated with the sampling event are now provided in Appendix B. 5. Comment: The Division evaluated the data in this report and previously submitted reports with regard to the potential for residual contamination in soil to impact groundwater. Based on this evaluation, the Division believes that groundwater will not be impacted and that Thiokol has satisfied the requirements of R315-101-3 (Principle of Non-degradation). The evaluation completed by the Division is described below: • The USU reports identify several uncertainties with regard to the potential for leaching of metals to groundwater at M-39 and M-636. To further evaluate these uncertainties since completing the removal action and confirmation sampling, the Division compared the recent soil sample results with the EPA Region IX default soil screening values for cadmium (8.0 mg/kg) and silver (34 mg/kg). This comparison indicates that cadmium contamination in the soil is not expected to migrate to groundwater at either site, but silver may migrate to groundwater at both sites. The average silver concentration in the soil is about 125 mg/kg at M- 39 and about 325 mg/kg at M-636. Both values are greater than the EPA default value of 34 mg/kg, but less than the site-specific soil screen value of about 400 mg/kg estimated by the Division. This soil screen value was estimated using the EPA tap water PRG of 0.18 mg/L, default Dilution Attenuation Factor (DAF) of 20 and a site-specific soil-water partition co-efficient (Kd) of 110 L/kg (EP A, I996);(0.I8 mg/L x 20 (unitless) x 110 lAg = 396 mg/kg). Please note that the Kd value used above is based on a soil pH of 8 (assumed limestone provenance and moderate alkalinity of the soil) and that some of the values used in the soil screening equation such as air porosity, water porosity and bulk density become negligible in the estimate of soil screen values for silver. Please note this estimate is site specific and may not be applicable at other sites. Response: The Division's evaluation of the potential for migration of contaminants from soil to groundwater is summarized in Section 3.2.3 of the revised report. For the sake of completeness, the line of reasoning developed in the 2003 Sampling and Analysis Plan, which reached the same conclusion as the Division's assessment, is included in Section 2.1 of the revised report. 6. Comment: Please add a section titled Post-Closure Plans, This section should indicate how groundwater related issues at both sites will be addressed, and that Thiokol will produce a Land-Use Tracking Plan addressing long-term management of soil at M-636. The plan should address tracking to monitor excavation of soil at M-636 and to insure that site use remains compatible with an industrial closure. In addition, a notice on the land deed is needed to acknowledge the soil contamination and land use limitation at the M-636 site. These requirements also applied to the M-508 site, as was stated in the letter regarding the closure of HWMUs M-114 and M-508 that was sent to your office on July 25, 2003. Response: A section on post closure plans has been added as Chapter 4 of the revised report. 7. Comment: The cover letter with this document indicates there is no ecological risk associated with this site, but no data or other information is provided in the report (o support this conclusion. Please provide an ecological risk assessment for each site as required in R315-10I. Response: Ecological risk is addressed in Section 2.3 of the revised report. 8. Comment: Please modify Section 2.2.3 and address accuracy and completeness for the soil sample results. Spike recoveries should be presented and discussed in the report. It appears that all planned samples were collected and that all sample results are usable, thierefore; completeness should be close to 100%, but a project completeness value should be added to the text. Sample representativeness is adequately addressed in the text. An assessment of precision, accuracy, representativeness and completeness (PARC) for the soil gas samples should also be presented. • It is noted that, although several duplicate results have relative percent differences (RPDs) exceeding analytical control limit goals, all of the duplicate sample result are less than the respective PRGs proposed for each site. Please provide additional detail regarding sample collection procedures for duplicates. Response: The quality assurance discussion in Section 3.2.4 ofthe revised report has been updated to address the above concems. The first paragraph of Section 3.2.4 has also been modified to refer to Section 4.1.2 of the 2003 Sampling and Analysis Plan for information conceming procedures used for the collection of duplicate samples. SCANNABLE MATERIALS associated with tliis document have been sent to be processed.