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HomeMy WebLinkAboutDSHW-2017-004922 - 0901a068807109cc DSHW-2017-004922 195 North 1950 West • Salt Lake City, UT Mailing Address: P.O. Box 144880 • Salt Lake City, UT 84114-4880 Telephone (801) 536-0200 • Fax (801) 536-0222 • T.D.D. (801) 536-4284 www.deq.utah.gov Printed on 100% recycled paper State of Utah GARY R. HERBERT Governor SPENCER J. COX Lieutenant Governor Department of Environmental Quality Alan Matheson Executive Director DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL Scott T. Anderson Director June 19, 2017 Kris Blauer, Manager Environmental Services ATK Launch Systems – Promontory P.O. Box 707 Brigham City, UT 84302-0707 RE: Human Health Risk Assessment for Groundwater ATK Launch Systems – Promontory Facility UTD009081357 Dear Mr. Blauer: The Division of Waste Management and Radiation Control has completed its review of ATK’s responses to our comments on the Human Health Risk Assessment for Groundwater. Based on our review, ATK has adequately addressed most of the comments. However, there are a number of issues that still need to be resolved or clarified. These issues are discussed in the enclosed document. Only the comments that have not been fully addressed by ATK are discussed. Once ATK has had the opportunity to review our responses, the Division proposes that a meeting be held to talk about the issues and reach an agreement on how the revised risk assessment will be conducted. If you have any questions, please call Jeff Vandel at (801) 536-0257. Sincerely, Scott T. Anderson, Director Division of Waste Management and Radiation Control (Over) STA/JV/jr Enclosure: Comments on the Draft Human Health Risk Assessment for Groundwater c: Grant Koford, EHS, Environmental Health Director, Bear River Health Department Lloyd C. Berentzen, MBA, Health Officer, Bear River Health Department Moye Lin, USEPA Region 8 Paul Hancock, ATK Launch Systems EVALUATION OF ATK’S RESPONSES TO THE DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL’S COMMENTS ON THE DRAFT HUMAN HEALTH RISK ASSESSMENT FOR GROUNDWATER AT THE ATK LAUNCH SYSTEMS, PROMONTORY FACILITY, PROMONTORY, UTAH Below is an evaluation of responses to comments on the Draft Human Health Risk Assessment (HHRA) for Groundwater at the ATK Launch Systems (ATK), Promontory Facility. Only those comments which have not been fully addressed are discussed. Please refer to ATK’s Response to Comments document for background and context on the issues discussed. The comments are organized by March, 2010 Conference Call General Topics, General Key Topics and Specific Comments. There are a number of key issues that the Division would like to discuss (identified below) with ATK prior to the revision of the risk assessment. March 11, 2010 Conference Call General Topics: 1. Bullet #1 - It is stated in the first bullet that ATK will evaluate each groundwater contamination plume separately and estimate the risks for each plume. It has been determined that groundwater contamination at Promontory will be evaluated by exposure unit. Just for clarification, does ATK consider each exposure unit to be an individual plume? 2. Bullet #2 - Our understanding from the March 11, 2010 meeting was that ATK would not evaluate a farmer exposure scenario, but would evaluate the ingestion of homegrown produce watered with contaminated groundwater as part of the current off-site residential scenario and future potential residential scenario. However, ATK indicates on p. 1 of the Responses (and throughout the Response document) that the current potential off-site resident scenario will not include the evaluation of plant uptake or other secondary exposure uptake pathways because of the high level of total dissolved solids (TDS) which precludes vegetable gardens or rearing animals. Exposures associated with a home garden scenario are unlikely to contribute substantially to the overall estimates of risk and hazard, but do represent a viable set of exposures (cattle do ingest water at Pipe and Shotgun Springs). The Division would like to see these secondary exposure pathways evaluated in the quantitative assessment (exposure assumptions and parameters could be discussed) since they are located off-site and could potentially exist at some point in the future. If this secondary exposure pathway is not evaluated quantitatively, ATK will need to support not doing it with TDS data and other documentation to demonstrate that the expected levels of TDS that could apply to the off-site exposure area evaluated precludes vegetable gardens or the rearing of animals. 3. Bullet #3 – The Division would like to review the screening process that will be used to select COCs and the handling of non-detect compounds prior to ATK’s revision of the risk assessment. In addition, please update Table 2-3 of the HHRA Report as needed so that the most current MCL or RSL is used. 4. Bullet #5 - There may be some chemicals that have low detection frequencies that are not artifacts of the analytical process (e.g. RDX). Could ATK provide a list of the chemicals that it suspects are artifacts and will be addressed in the uncertainty section? 5. Bullet #6 – Hexavalent chromium that has been detected in the M-508 wells is a contaminant that has been released and should be included in the quantitative evaluation. If the other metals that are included in the Groundwater Protection Standard Table in the Post-Closure Permit are evaluated qualitatively, ATK needs to provide supporting evidence for that approach for each metal. 6. Bullet #7 – The Division has no plans to investigate potential mechanisms for elevated arsenic concentrations. 7. Bullet #8 - The March 11, 2010 meeting did not reach a final agreement on whether modeled concentrations or actual measured on-site groundwater data, absent any modeling, would be used to evaluate either an off-site current resident or a future hypothetical resident. While the groundwater model has been approved by the Division, it is recommended that at least one residential exposure scenario be evaluated in the revised HHRA that is solely predicated on current measured groundwater data, absent any modeling or attenuation (i.e., use of concentrations at the center of the existing plume to conservatively represent future potential off- site concentrations, assuming no attenuation). This assessment basis will provide the Division with an upper-bound estimate of potential risks or hazards. While this assessment basis may not be the selected platform for remediation decisions, it may provide a bounding estimate and the demonstrated need for additional scrutiny/oversight. The Division recommends further discussion on this issue. 8. Bullet #9 – The Division agrees that vapor intrusion should be re-evaluated in the revised risk assessment by following the US EPA 2002 vapor intrusion guidance for applicable locations (where groundwater is shallower than 100 feet). However, in regard to the use of the Johnson- Ettinger model (JEM), while it may be used to support the need for a vapor intrusion assessment, where groundwater screening criteria are exceeded, the Division would like to remind ATK that the JEM is not defensible as a single line of evidence to disprove vapor intrusion potential where groundwater exceedances have been recorded. For additional information, or a reminder, please see Additional Comment #3 (page 34, ATK Response to Comments Document, October 11, 2010). The Division would like to discuss the use of the JEM for screening candidate buildings as was proposed by ATK in your response to this comment. 9. Additional Bullet - The Division understood from the March 11, 2010 meeting that non-detected compounds would be evaluated on the basis of their Sample Quantitation Limits (SQLs) rather than the Method Detection Limits (MDLs). However, it appears that ATK plans to use MDLs to evaluate non-detected compounds. Please clarify why ATK prefers to use MDLs over SQLs. If MDLs will be used to evaluate non-detected compounds, the uncertainty analysis will need to present and describe any uncertainties associated with analysis variability, including instances where the MDL approaches (i.e., is within an order of magnitude) the most relevant health-based screening criterion. Please ensure that MDLs or SQLs are low enough for evaluating non- detected compounds. EVALUATION OF THE RESPONSES ON THE GENERAL KEY TOPICS Evaluation of the General Response, Pages 3 through 5: ATK’s General Responses given on pages 3 through 5 are discussed below: 1) Each Groundwater Plume will be a separate Exposure Unit The Division would like to discuss Table 1- Preliminary Exposure Units and issues related to the data that will be used for the calculation of exposure concentrations. 2) Detection Limits and the Chemical of Potential Concern Selection Process Non-detected compounds should be evaluated on the basis of the Sample Quantitation Limits (SQLs) rather than Method Detection Limits (MDLs) (see Conference Call General Topic #9). If MDLs (rather than SQLs) will be compared to Regional Screening Levels (RSLs) in the revised HHRA, please ensure that the uncertainty analysis describes any uncertainties associated with analysis variability, including instances where the MDL approaches (i.e., is within an order of magnitude) the most relevant health-based screening criterion. 3) Background Metals and High Metals in Groundwater All inorganics that exceed applicable risk-based screening criteria should be carried forward in the risk assessment. The uncertainty analysis may then include a refinement of the total risk by expressing total risk as background risk and site-related risk. Please ensure that all risks and hazards are quantified for all inorganics that exceed applicable risk-based screening criteria. Arsenic, barium, beryllium, chromium, cobalt, molybdenum, perchlorate and nitrate are all included in the Post-Closure Permit, Groundwater Protection Standard and need to be addressed in the HHRA on some level. Chromium and some of the other metals detected appear to be from the degradation of stainless steel. However, chromium and hexavalent chromium detected in the M-508 area is a contaminant released by ATK that should be included in the quantitative evaluation. The Division proposes further discussion on how metals will be evaluated. 4) Residential Exposure, Groundwater Modeling and Future Potential Groundwater Contaminant Concentrations See the evaluations of Conference Call General Topics #2 and #7 above. 5) Vapor Intrusion See the evaluation of Conference Call General Topic #8 above. EVALUATION OF THE RESPONSES TO ORIGINAL GENERAL AND SPECIFIC COMMENTS Evaluation of the Response to Specific Comment 4, p. 7: The Division would like to discuss how the data sets will be generated for the Exposure Units. From a HHRA perspective, the most current data from the wells that represent the center of the contaminant plumes is preferred for developing exposure point concentrations. Evaluation of the Response to Specific Comment 7, p. 9: As discussed in General Key Topic #3 above, the Division agrees, in general, that elevated concentrations of chromium and molybdenum observed are due to the degradation of stainless steel well parts. However, the elevated concentrations of hexavalent and total chromium detected in the M-508 wells are the result of contamination released from building M-508 and should be evaluated in the quantitative section of the HHRA Report. Inorganics should not be eliminated from the quantitative assessment on the basis of background. All inorganics that exceed applicable risk-based screening criteria should be carried forward in the risk assessment. The uncertainty analysis may then include a refinement of the total risk by expressing total risk as background risk and site-related risk. In addition, potentially elevated concentrations of beryllium were detected in wells G-6, G-7 and G-8 and beryllium is included in the Groundwater Protection Standard table in ATK’s Post-Closure Permit. Beryllium needs to be evaluated in the HHRA on some level. Evaluation of the Response to Specific Comment 8, p. 10: The Division agrees that contaminants should be re-screened for each EU to determine if they exceed the most current RSLs. There have been many detections of cis-1,2-DCE, some off-site, that exceed the current tap water RSL. Cis-1,2-DCE should not be excluded as a COC from the quantitative assessment. Evaluation of the Response to Specific Comment 9, p. 10: HMX and RDX are included in Table IV- 1, Constituents and Groundwater Protection Standard, of the Post-Closure Permit and have been detected in groundwater monitoring wells at Promontory in the past. As shown in the table below, RDX has been detected in wells A-8, B-2D, B-3 and C-5 at concentrations that exceed the EPA Regional Screening Level for tap water. Therefore, RDX and HMX (other explosives?) should be included in the selection of chemicals of potential concern (COPC) for the applicable exposure units (EUs). The Division recommends that a review of existing explosives data be conducted. Is the existing data adequate or should additional samples be collected so that current site conditions are represented? Have wells A-3 or D-1 been sampled for explosives? ATK – Promontory Detections of RDX and HMX – 2001 to 2010 Evaluation of the Response to Specific Comment 10, p. 11: The statement given in the response “The risk assessment submitted to the Division included the risks under baseline conditions” is not understood since “baseline conditions” refers to evaluating site conditions in the absence of remediation, institutional or engineering controls. On-site groundwater at Plant 3 was evaluated in the HHRA assuming exposure after wellhead treatment. Evaluation of the Response to Specific Comment 11, p. 11: The Exposure Units and associated data sets that will be used in the revised risk assessment should be discussed prior to the revision of the HHRA. Well RDX (ug/L) HMX (ug/L) Date A-2 < det. 1.44 10/25/2001 A-2 < det. < det. 10/6/2008 A-2 < det. < det. 12/11/2008 A-5 <det. 0.547 10/25/2001 A-8 1.11 2.43 11/26/2001 B-2D 2.54 4.12 11/26/2001 B-3 2.11 2.51 10/10/2008 B-3 1.94 2.7 6/2/2010 C-1 < det. < det. 10/25/2001 C-1 <det. 1.73 10/14/2008 C-1 < det. 2.77 10/24/2008 C-5 0.867 1.69 11/26/2001 RSL - Tapwater 0.7 1000 May 2014 Summary Table Evaluation of the Response to Specific Comment 26, p. 16: The Division agrees that data adequacy for soil and sediments at each of the springs should be discussed. Soil and sediment samples at the springs will likely become an issue in the ecological risk assessment. Evaluation of the Response to Specific Comment 31, p. 17: Please see the Evaluation of ATK’s Response on General Key Topic, #2. Evaluation of the Response to Specific Comment 35, p. 18: The Division is in general agreement with ATK regarding chemicals that are laboratory artifacts or are not site-related. However, there may be some chemicals that have low detection frequencies that are not artifacts of the analytical process (e.g. RDX). We propose further discussion on the chemicals that would be excluded. The uncertainty analysis should present sufficient justification for why such chemicals are artifacts or are not site- related. Evaluation of the Response to Specific Comment 38, p. 19: The response indicates that Fork and Conner Springs are beyond the boundary of the approved model, and then indicates that these springs will be included in the risk assessment, but are un-impacted by groundwater constituents at ATK. Please clarify how Fork and Conner Springs will be evaluated in the HHRA given that they are beyond the boundary of the approved model. The Division recommends that ATK continues to monitor these springs periodically. Evaluation of the Response to Specific Comment 39, p. 19: Please see the Evaluation of the Response to Specific Comment #35. Evaluation of the Response to Specific Comment 40, p. 19: Please see the Evaluation of the Response to Specific Comment #26. Evaluation of the Response to Specific Comment 42, p. 20: The response indicates previous agreement that, based on the poor groundwater quality, only direct exposure to groundwater would be included in the risk assessment process for residential exposure. While it was agreed during the March 11, 2010 meeting that a farmer scenario would not be evaluated, it was noted by the Division, as discussed above in Conference Call General Topic #2, that ingestion of homegrown produce should be evaluated for current off-site and future potential residents. Evaluation of the Response to Specific Comment 44, p. 21: Please refer to the Evaluation of the Response to Specific Comment 42. Also, note that groundwater west of the facility near drain field M-153 may have been used for agricultural purposes in the past (as noted in Specific Comment 46). Given that a farmer scenario will not be evaluated in the revised HHRA, please ensure that the uncertainty analysis supports this approach. Evaluation of the Response to Specific Comment 46, p. 21: Please refer to the Evaluation of the Response to Specific Comment 44. Evaluation of the Response to Specific Comment 53, p. 23: Please refer to the Evaluation of ATK’s General Response and Responses to Specific Comments 42 and 44. Evaluation of the Response to Specific Comment 57, p. 24: The response states, “The recalibrated model will be used to calculate the risks for Promontory. Because the model affects all future potential exposures, the recalibrated model will be used to estimate future risks for.” The Division agrees that the recalibrated model should be used to estimate future risks for on-site exposure, including vapor intrusion, and off-site exposure including residential exposure pathways at the Springs. However, as discussed in Conference Call General Topic #7, it is recommended that at least one residential exposure scenario be evaluated in the revised HHRA that is solely predicated on current measured groundwater data, absent any modeling or attenuation (i.e., use of concentrations at the center of the existing plume to conservatively represent future potential off-site concentrations, assuming no attenuation). This assessment basis will provide the Division with an upper-bound estimate of potential risks or hazards. The Division recommends further discussion on this issue. Evaluation of the Response to Specific Comment 60, p. 25: Please use the cancer slope factor provided for 1,1-dichloroethane in EPA’s May 2010 RSL Table of 5.7E-03 (mg/kg-day)-1. This value was established by California’s Office of Environmental Health Hazard Assessment, CalEPA: http://www.oehha.org/risk/ChemicalDB/cancerpotency.asp?name=1%2C1%2DDichloroethane&number =75343 . Evaluation of the Response to Specific Comment 62, p. 25: Please refer to the discussion in Conference Call General Topic #2. Evaluation of the Response to Specific Comment 66, p. 26: The Division would like to discuss in more detail how exposure point concentrations will be calculated for exposure units on and off site before the risk assessment is revised. Evaluation of the Response to Specific Comment 70, p. 26: The Division agrees with ATK’s response. However, please note that when evaluating inorganics, the background statistical analyses used to determine the upper tolerance limits (UTLs) for inorganics should remove outlier data. EVALUATION OF THE RESPONSES TO ADDITIONAL COMMENTS The Division is in agreement with ATK’s responses to the Additional Comments. EVALUATION OF THE RESPONSES TO SUPPLEMENTAL COMMENTS Evaluation of the Response to Supplemental Input on Specific Comment 25, p. 41: Please refer to Conference Call General Topic #9. Evaluation of the Response to Supplemental Input on Specific Comment 71, p. 42: Please refer to Conference Call General Topic #7.