A. Department of Toxic Substances Control Barbara Lee, Director Matthew Rodriquez 8800 Cal Center Drive Edmund G. Brown Jr. Secreta for . . Governor Sacramento, California 95826-3200 April 13, 2017 Ms. Stephanie Jennings NEPA Document Manager US. Department of Energy 4100 Guardian Street, Suite 160 Simi Valley, California 93063 DEPARTMENT OF TOXIC SUBSTANCES COMMENTS ON THE DEPARTMENT OF DRAFT ENVIRONMENTAL IMPACT STATEMENT FOR REMEDIATION OF AREA IV, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA Dear Ms. Jennings: The Department of Toxic Substances Control (DTSC) has completed its review of the Department of Energy?s (DOE) draft Environmental Impact Statement for Remediation of Area IV and the Northern Buffer Zone of the Santa Susana Field Laboratory (SSFL) and would like to thank DOE for the opportunity to provide the following comments. We summarize our key concerns with DEIS in this cover letter, and include a more thorough discussion of specific concerns in the attachment to this cover letter. Key Concerns with DEIS 1. The DEIS fails to only include alternatives that describe how DOE will comply with the 2010 Administrative Order on Consent (AOC). This is inconsistent with earlier statement describing the cleanup?s purpose and need. Given this, we must reiterate that DTSC will hold DOE accountable for complying with the A00. 2. The DEIS fails to provide sufficient information or analysis for DTSC to determine if any of the alternatives would comply with the AOC. Ms. Stephanie Jennings April 13, 2017 Page 2 3. The DEIS describes at length a number of challenges to implementing of the AOC, however, it fails to take a hard look at how to overcome those challenges, including: a. Inadequate survey, analysis, and use of agreed upon processes to identify potential options for acquiring clean back?ll soil. DOE will use this soil to achieve cleanup standards and restore the land?s natural contours following the removal . of contaminated soil. Conclusory statements about inability to achieve the preliminary cleanup standards, which are contained in the project?s ?Look-Up Table? (LUT), without a thorough examination of available options for overcoming those challenges. 4. The assumes habitat for protected plants and animals is exempted from cleanup, but fails to explain how DOE proposes to utilize the process of conferring with state and federal agencies on site?speci?c decisions to protect habitat. 5. The DEIS proposes to rely on the natural process of degradation (monitored natural attenuation) to reduce levels of certain contaminants to achieve cleanup standards, which may take decades and therefore violate the prohibition on leaving contamination where it is found. Moreover, the DEIS fails to examine ways to accelerate the natural degradation process. 6. The DEIS assumes trucks will use 2019 air pollution control technology over the estimated 15-year timeline for the cleanup. This fails to account for the use of improved air pollution control technologies over time, which in turn undercuts the analysis needed of the project?s potential air pollution impacts. The DEIS Appears to be Inconsistent with Established Purpose and Need for the Cleanup Project The National Environmental Policy Act (NEPA) compels DOE to analyze the environmental impacts of this cleanup project, and establishes certain requirements when DOE conducts its analysis. One such requirement is that DOE must describe the purpose and need for taking this action. This Purpose and Need Statement explains the reason DOE is proposing the cleanup, what DOE expects to achieve with the cleanup, and provides the basis for DOE's development of a reasonable range of alternatives in its NEPA document for the cleanup. DOE issued a Notice of Intent (NOI) to prepare an Environmental impact Statement for this cleanup in February of 2014. This NOI contained a revised purpose and need for Ms. Stephanie Jennings April 13, 2017 Page 3 the cleanup project that stated, needs to complete remediation of SSFL Area IV and the Northern Buffer Zone to comply with applicable requirements for radiological and hazardous contaminants. These requirements include regulations, orders, and agreements, including the 2007 Consent Order, as applicable, and the 2010 In our April 1, 2014 letter regarding DTSC emphasized the importance that alternatives must comply with the ADC and applicable State laws and regulations for the soil cleanup. The draft identi?es four possible soil cleanup alternatives: 1. No Action Alternative 2. Cleanup to AOC Look-up Table (LUT) Values 3. Cleanup to Revised LUT Values 4. Conservation of Natural Resources Based on the information provided in the DEIS, the alternatives appear to be inconsistent with Purpose and Need Statement. It appears that alternatives 3 and4 do not meet the AOC requirements. In addition, while DOE states that alternative 2 does meet the AOC requirements, the data and analysis in the DEIS do not suf?ciently support an AOC cleanup. - The DEIS Fails to Provide Suf?cient Information to Determine if any Alternatives Comply with the A00 The DEIS fails to completely justify the interpretation of areas that contain protected biological and cultural resources that may qualify for an exception to the cleanup requirement. DOE has failed to justify the-seexception areas, as de?ned in the AOC, for a? alternatives. Similarly, DOE identi?es monitored natural attenuation of waste that is overly broad given the potential time needed to complete degradation. There is uncertainty about whether this process can achieve suf?cient degradation to comply with the Because alternatives 1, 3, and 4 do not, on their face, comply with the AOC, they are not feasible for analysis. Therefore, DTSC did not comprehensively review those alternatives and has provided only limited comments related to these three alternatives. Ms. Stephanie Jennings April 13, 2017 Page 4 The DEIS Focuses on Technical Challenges Without Suf?ciently Analyzing Options to Overcome Those Challenges The DEIS identi?es a number of areas where it claims that implementing the AOC poses technical challenges, but does not suf?ciently pursue possible solutions. By overlooking solutions to these challenges, DOE is making the case that it cannot implement the A003 in an effective manner. DTSC is committed to require that DOE comply with the A00, and DOE must pursue solutions to achieve that compliance. For example, assertion that it is not possible to ?nd backfill that will meet the LUT values is not fully supported. Whether the goal is to meet the LUT values or biological needs for successful mitigation, the composition of the back?ll is a very important factor. While DOE did find back?ll areas that had values exceeding the LUT values, DOE did not adequately explore areas for potential ?ll that had similar lithology and chemical makeup. In addition, DTSC has neither been engaged in, nor aware of any efforts DOE has made to coordinate its efforts with US EPA as speci?ed in the AOC. Finally, the Con?rmation Protocol, Attachment of the AOC, includes the following: If an onsite or offsite source of back?ll soils that achieves all Look-up Table values cannot be reasonably found, then DTSC, DOE and USEPA shall enter a consultation process and DTSC shall determine the best available source of back?ll. Please note that, while DOE provided limited information to DTSC in a December 21, 2016 letter regarding back?ll material, as of this writing there has not been any follow?up with DTSC about this consultation process. DOE makes a number of conclusive criticisms of the LUT values. DTSC does not accept all of DOE's conclusions. For example, while DEIS has identified the technical false "positive, and achieving the Minimum Detection Concentrations (MDCs) as issues associated with implementation, DOE has not proposed speci?c resolutions. There are a number of concepts that DTSC believes may help resolve these issues, - such as the following: 0 Improving speci?c cleanup data quality objectives. 0 Examining multiple laboratories? capacity to achieve M003. 0 Evaluating methods to improve biphenyl detection issues. The A00 Confirmation Sampling Protocol refers to comparing the ?contaminants of concern observed in the confirmation samples? to LUT values. Developing a more precise list of contaminants of concern that more accurately reflects the most indicative Ms. Stephanie Jennings April 13,2017 Page 5 chemicals at the site, rather than all of the possible chemicals, would reduce both the likelihood of false positives, and focus attention on the impacted'areas. The DEIS Assumes Habitat is Exempt from Cleanup Without Explaining how DOE will Confer with State and Federal Wildlife Agencies Responsible for Assessing Protected Habitat - . The identification of areas subject to no cleanup through the application of biological exceptions, as de?ned in the AOC, is far too generalized. These determinations will require speci?c and final input and opinions from both the US Fish and Wildlife Service and California Department of Fish and Wildlife. DTSC is not endorsing the areas DOE identified as exceptions in the DEIS. As they represent preliminary estimates, DTSC will oversee and approve the ?nal determination regarding exceptions as de?ned in the AOC when there is suf?cient data and area speci?c analysis to support a ?nal decision. The DEIS Presumes the Natural Degradation of Certain Contaminants will Achieve AOC Cleanup Standards Without Suf?cient Support or' Analysis In the DEIS, DOE referenced the use of in-situ biotreatment of soil. DTSC recommends that DOE explore methods and technologies that can accelerate the degradation of key contaminants such as total petroleum hydrocarbons and aromatic hydrocarbons in order to shorten cleanup timeframes and reach the goals of the AOC with greater certainty. DTSC retains authority and jurisdiction to direct additional actions over any areas where monitored natural attenuation or biotreatment is part of the proposed remedy. DTSC will consider the cleanup actions ability to achieve the cleanup values and timeliness to complete cleanup when evaluating cleanup methods. The DEIS Fails to Appropriately Analyze Vehicles? Use of Air Pollution Control Technologies that Improve Over Time The DEIS discusses mitigation measures designed to minimize the project?s potential harmful impacts on air quality. A key mitigation measure is the assumption that DOE will require trucks, which haul soil to and from Santa Susana, to use 2019 emission control technologies over estimated 15-year timeline for the cleanup project. This fails to recognize that air pollution control technology improves over time. Since construction of the project will probably take several years, DTSC recommends that final EIS specify, for each year of the project, the earliest allowable model year of trUck that DOE Ms. Stephanie Jennings April 13, 2017 Page 6 will use during construction. Relatedly, the final should also analyze the air pollution control benefits related to this revised mitigation measure. Please note that additional section-specific comments are attached. Again, DTSC appreciates the opportunity to comment on DEIS for this site and we look forward to working with DOE in achieving the cleanup in a manner consistent and in compliance with the AOC. If you have questions regarding the comments, please contact me at Mohsen.nazemi@dtsc.ca.gov, or one of my staff, Ray Leclerc at Ray.Lecrlerc@dtsc.ca.gov. (916-225-3582), or Mark Malinowski at Mark.Malinowski@dtsc.ca.qov, (916-225-3717). Sincerely, Mohsen azemi, M.S., P.E. Deputy Director Brownfield Environmental Restoration Program Department of Toxic Substances Control Attachment: DTSC Speci?c Comments cc: (via email) Mr. John Jones Federal Project Director DOE-ETEC John.Johns@emcbc.doe.gov Mr. Ray Leclerc Division Chief Brownfields Environmental Restoration Program Department of Toxic Substances Control Ray.Leclerc@dtsc.ca.qov Ms. Stephanie Jennings April 13, 2017 Page 7 cc: (Via email) Mr. Mark Malinowski Branch Chief Santa Susana Field Laboratory and Northern California School Branch Department of Toxic Substances Control Mark.Malinowski@dtsc.c.aqov Ms. Nancy Bothwell, Senior Staff Counsel Department of Toxic Substances Control Nancy.Bothwell@dtsc.ca.qov Mr. Roger Paulson Unit Chief Santa Susana Field Laboratory Team Department of Toxic Substances Control Roger.Paulson@dtsc.ca.qov Ms. Laura Rainey Senior Engineering Geologist Department of Toxic Substances Control Laura.Rainev@dtsc.ca.gov The Department of Toxic Substances Control?s Detailed Comments on the Department of Energy?s (DOE) draft Environmental Impact Statement (DEIS) for Remediation of Area IV and the Northern Buffer Zone of the Santa Susana Field Laboratory (SSFL) (January 2017). Main Comments 1: Chapter 1: Project Approach: DTSC strongly reiterates that the completed soils cleanup in Area IV and the Northern Buffer Zone (NBZ) will ultimately require full compliance with the 2010 Administrative Order on Consent (AOC) requirements and this must be re?ected in EIS. Also, the EIS must make it clear that key elements of the proposed soil remediation alternatives must comply with the AOC requirements. For example, Section 7.11 of the AOC states ?All actions taken pursuant to this Order by DOE shall be undertaken in accordance with applicable local, State, and federal laws and regulations?. DTSC recognizes that evaluation of the Soil No Action Alternative is required by Council on Environmental Quality National Environmental Policy Act (CEQ NEPA) regulations. Ultimately however, the cleanup remedy selected must comply With the A00. The EIS must include a clearer discussion of potential use of the alternatives analysis in various phases of the cleanup, and clarify that ultimate requirement of full compliance with the A00 is necessary. Section 1.3, Page 1-7, 2010 A00 Text Box: The last sentence in the text box indicates ?Per the 2010 A00, the schedule shall ensure that the identi?ed activities can be accomplished by 2017 or sooner?. To clarify, the DTSC- approved Soils Remedial Action Implementation Plan (SRAIP) will include a schedule for implementation of the planned remedial actions. Section 7.17 of the AOC states that all plans, schedules, and reports that require DTSC approval and are submitted by DOE pursuant to the Order and are not subject of dispute resolution under Section 7.19.1 through 7.19.9 are incorporated in the Order upon approval by DTSC. The schedule contained in the DTSC-approved SRAIP decision document will be the DTSC approved schedule, under the Order. Section 2.2.1, Page 2-4: DOE states their expectation, that in order for implementation of any alternative to be consistent with the AOC, changes to the AOC would be required. Please note that as mentioned earlier, DTSC is committed to fully enforcing the 2010 A00 requirements. Section 2.2.3, Page 2-12: DOE states if an area with chemicals or radionuclides exceeding AOC LUT values is inaccessible for safety reasons, the AOC allows exemptions of up to 5 percent of the total volume of soil above AOC Look-Up Table (LUT) values. This exemption is described in Attachment ?Final Page 1 of 7 Agreement In Principle? of the AOC. However example for use of this exemption (safety Issues due to inaccessibility) is subject to DTSC approval In the ?nal cleanup decision documents . Section 2.3.2, Page 2-22 and Appendix D, Page 0-45 Concerns about Locating Back?ll Material Meeting AOC. LUT Values: The Final Agreement in Principle of the AOC states that back?ll/replacement soils must not exceed local background levels, but if back?ll that meets the LUT values cannot be reasonably found, then after consultation between DTSC, DOE and USEPA, DTSC shall determine the best available source of back?ll. The following concepts are potential systematic approaches for working within the framework of the point-by?point comparison process with the LUT for chemicals, and for managing the uncertainty that may lead towards generation of false positives. Ultimately, DTSC will need more data to evaluate the acceptability of off~site back?ll soils, as well as the ability to verify these results. Since the ?rst proposed project involves priority cleanup of radionuclides to LUT values with cleanup of nearby chemicals to these suggested steps for determining if pctential backfill exceeds local background for chemicals may be of lesser priority . . Develop Constituents of Concern. 0 Sample results used for comparison to AOC LUT values should be at or above the Method Reporting Limit (MRL). . Sample analyses and results should consider and minimize to the extent possible, analytical challenges for low levels of TPH and naturally-occurring organic materials. 0 Sample analyses should consider, and minimize to the extent possible, analytical challenges for pesticides, herbicides and PCBs. 0 Sampling of potential source should be designed to minimize sampling error. a Back?ll should be assessed for biological suitability. . Section 2. 3. 3, Page 2-25: Third ngh: This section indicates, ?The 2010 A00 cOn?rmation protocol addresses and compares every soil sample with the AOC LUT values for 116 chemicals and 16 radionuclides. The A00 5 Con?rmation Protocol (Attachment C) states that ?The concentrations of radiological and chemical contaminants of concern (COCs) observed in the confinnation samples will be compared directly to the concentrations listed in the ?Look-up? Tables of radiological and chemical cleanup levels.? Con?rmation sampling can potentially utilize COCs to represent the key contaminants of interest for purposes of making con?rmation decisions. The ADC requirements refer to 0003 in the confirmation sampling process. . Section 2.4.1, Page'2-31, Cleanup to Revised LUT Values Alternative: As previously stated, this Alternative does not appear on its face to Comply with the Page 2 of 7 AOCs. Regarding phased approaches to cleanup, any soil with contamination above the LUT values at the end of the ?rst phase would need to be remediated to comply with the A003 in the second phase. Page 2-33, Conservation of Natural Resources Alternative: The ?rst paragraph in this section states that under this alternative, Area IV soils would be cleaned up to Suburban Residential risk-based screening levels for chemicals. Radionuclides would be remediated "to levels as low as reasonably achievable (ALARA) below the DOE standard of 25 millirem per year (DOE Order 458.1) to the hypothetical suburban resident." However, the AOC states that soil cleanup is to be to Background levels. The Natural Resources Alternative does not comply with the AOC. Section 3.4.2.1, Pg. 3-41, 4. The text in the draft EIS states: ?The purpose of the is to collect data on aquifer properties, remove some contaminants mass, and possibly control plume migration for locations within that exceed 1, 000 parts per billion TCE in groundwater. For Area V, this de?nition applies to To clarify, DTSC stated that ?groundwater extraction should be initiated at all groundwater monitoring wells within source zones, de?ned as any monitoring wells where the reported concentrations of TCE have been 1,000 ug/L or higher and/or any monitoring wells where TCE concentrations and water levels are trending higher since shut-down of groundwater extraction wells.? The text in the EIS should be modi?ed to accurately re?ect the purpose of the Groundwater lnterim Measures (GWIM). '10.Section 4.1.1, Page 4-8: Please con?rm the statement regarding zoning for the 11. Northern Buffer Zone and other areas of Santa Susana for consistency with Ventura County?s zoning designations, including the county?s General Plan. Table 6-2 (Potential Mitigations), Page 6-17: Mitigation Measure AQ-1 states ?For on-road trucks, a ?eet of trucks no more than 5 years old.? In order to minimize the air quality impacts of the project, DTSC recommends that the final EIS specifies the use of the earliest allowable model year of trUck during construction, which may expand over several years. DOE should also specify which model year haul trucks will be used in each year during construction phase of the project, in Final EIS. Relatedly, the final EIS should also analyze the air pollution control bene?ts related to this revised mitigation measure. Page 3 of 7 Specific Comments 12. Section 2.6.3, Page 2-52: Text states ?The Metals Clari?er TCE plume and the RMHF TCE plume concentrations are less than 10 parts per million?. Units should be corrected to parts per billion. 13.Section 2.8.1.4, Page 2-106, 3 (Climate Change): Text indicates, ?Peak annual emissions of 002 would range from about 3,000 to 8,900 metric tons?. The upper range for the cleanup to revised LUT scenario (17,000 metric tons) is higher than the upper range for the LUT scenario (8,900 metric tons). Please correct or explain these values. 14.Section 3.1.1, Page 3?3, 5: Text indicates that Runkle Canyon is to the northeast, but it actually is to the northwest of SSF L. Please clarify or correct. 15. Figure 3-13, Page-3-23: Features described in the legend are not consistent with what is depicted in the Figure. For example, underground storage tanks are listed in the key, but are not shown in the ?gure. In addition, some RFI sites shown in the ?gure are not listed under the key. Please address for consistency. 16'. Section 3.2.5.3, Page 3-27, 4: The reference cited for ?Rocketdyne, 2000? does not appear on DOE's website list of references for Chapters 1 through 8. 17.Section 3.2.5.4, Page 3-29: The ?rst paragraph of this section indicates, ?The 2010 A00 (DTSC 2010a) addresses soil and bedrock containing chemicals and radionuclides exceeding LUT values." To clarify, section 1.8.4 of the AOC includes weathered bedrock within the de?nition of ?soils?. 18 Section 3. 4. 2. 8, Page 3-45: The cited reference for 2008' IS presumably intended to address Building 4100, yet the document makes no mention of this building. Please clarify. 19. Section 3.9.2, Page 3-103, (Public Radiation Exposure): The second paragraph in this section states that DOE collects air samples and monitors radiation at locations in and around Area IV and the Northern Buffer Zone (NBZ). Please indicate how long DOE has been collecting such radiation monitoring data, and where the public can access it. 20. Section 3.10.2, Page 3-122: Last ngh: To clarify for the RMHF, an interim status Part A application was accepted and unit was granted interim status, and thus subject to RCRA regulations for Interim Status, which are similar to or more prescriptive than RCRA regulations for permitted units. Reference to is likely a typographical error, and likely should be HWMF. 21. Section 4.3.1.2, Page 4-39: Last ngh: Refers to rainfall season of December through May, yet section 3.3.1 in the EIS refers to a different period (see page 3- 31 of Chapter 3). Please clarify or correct. Page 4 of 7 22. Section 4.4.3, Page 4-48, 3: The text states ?The three groundwater remediation alternatives?Groundwater No Action, Groundwater Monitored Natural Attenuation, and Groundwater Treatment?would all positively affect the quatity of groundwater resources.? This statement may be the result of the standard language used in the Draft EIS, however the determination that the No Action alternative has any effect, let alone a positive effect, is not supported. The statement should be modi?ed. 23.Section 4.11, Page 165, 2 -This paragraph fails to mention that DTSC would have discretion (in coordination with the SSFL Native American Council - NAC) over whether a listed or eligible resource would be handled under the exemption. 24. Section 4.11, Page 165, 4 Please indicate if all resources overlapping with clean up areas were tested such that eligibility for each listing could be determined. 25. Section 4.11, Page 165, 5 Please revise the text to include that NASA has determined this resource to constitute a Traditional Cultural Property (TOP). 26. Section 4.11.1, Page 166, Table 4-75 (Archaeology Cleanup Alternatives) - No historic properties affected for archaeology means that there will be no eligible or listed archaeological sites impacted whatsoever. The text should acknowledge that DTSC has discretion in applying the exemption. Also, the assertion that there will be no impacts to archaeological resources is contradicted in the TCP entries where it states there is potentialdiscovery of unanticipated archaeological sites. 27. Section 4.11.1.2, Page 167, 2 - According to records not all sites within clean up areas were subject to testing. Please con?rm or correct. 28. Section 4.11.1.2, Page 167, 4 The text mischaracterizes the AOC, which allows DTSC, in coordination with the NAC, to exercise discretion. It is not a blanket exception. Please revise the text. 29.8ection 4.11.1.2, Page 167, 4 - Archaeological resources should be evaluated under more than just Criterion especially in the context of a TOP. This evaluation of eligibility is insuf?cient for Section 106 and CEQA. 30. Section 4.11.1.2, Page 167, 4 - This section (Cleanup to AOC LUT Values) fails to address archaeological resources discoveries. Please revise the text. 31.Section 4.11.1.2, Page 168, 1 The text infers that archaeological resources could be evaluated on information potential alone. This would be an error in approach. Please revise the text. Page 5 of 7 32. Section 4.11.1.3, Page 168, 2 The text largely dismisses the potential for archaeological discoveries and follows with statement that "No historic properties would be affected". Provide explanation on how this is possible. . 33. Section 4.11.2.2, Page 170, 3 - NEPA requires analysisof impacts to ."cultural resources" whether they qualify as "historical properties" under the NHPA or not. The State Historic Preservation Officer?s concurrence under 106 does not change this NEPA requirement. 34. Section 4.11.2.2, Page 170, 5 - Same as previous. Section is analyzing only impacts to "historic properties". This does not meet the NEPA requirement. 35. Section 4.11.5, Page 174 - Which similar criteria for NEPA requires consideration of ?cultural resources" not limited to the NHPA. 36. Section 4.11.5, Page 174 The documents should acknowledge that resources may not be able to be avoided, both those we already know about and those that may be discovered. Coordination with the NAC will be of critical importance to address the issue. 37. Table 6-1 Measures to Minimize Impacts of Demolition and Remediation Activities at Santa Susana Field Laboratory and the Northern Buffer Zone; Item 3-2. ?The long-term groundwater monitoring program will be similar to the interim groundwater monitoring program now in place.? Although the DTSC does not currently anticipate extensive changes in the existing groundwater monitoring program, there will be modifications based on the ?nal remedies selected for the site. The extent of these modi?cations is unknown and will be determined based on the long term data needs only after ?nal groundwater remedies are selected. ?The site contractor will verily these actions to in semiannual groundwater - monitoring reports submitted by The text needs to include a statement that although the current groundwater monitoring program requires semiannual groundwater monitoring reports, this can be modi?ed as needed and directed by DTSC. 38. Section 7.2.3, page 7-17; 1st Pg ph: Text States: ?All the soil remediation action altematives, the Building Removal Altematives, and the Groundwater Treatment Altemative would require replacement of soil with backtill (including topsoil) obtained from offsite sources.? The text should specify if soil replacement would be necessary for the Groundwater Treatment Alternative. Appendix states, ?There would be no soil disturbance from the installation of groundwater treatment systems. Treatment systems would be constructed primarily on existing concrete pads and asphalted Page 6 of 7 ground. Any required piping (for groundwater or pressurized air) would be above ground.? 39. 3.2.3.2 Methods Used to Analyze and Quantity Impact; 3-8; 14: The text states, ?There would be no high?pressure injection of treated groundwater or groundwater amendments.? All groundwater remediation technologies need to be evaluated in the Corrective Measures Study, therefore this statement should be removed. 40. 3.2.3.2 Methods Used to Analyze and Quantify Impact; 1St ngh: The text states, ?The soil immediately above the strontium-QO-impacted sandstone would be removed, stockpiled, and replaced as backfill after the contaminated sandstone is removed. The basis for determining that the excavated soil will be consistent as backfill under the AOC needs to be provided. 41 . Page C1 -9. The following is stated in the table, ?Install long-term monitoring wells, including at the base of the Santa Susana Mountains where they intersect with the Simi Valley alluvium to detect migration of contaminants. Should this state ?at the base of Simi Hills? instead of ?Santa Susana Mountain?? 42.Table 0-3, Page D-12: Footnote 5 of this table states, ?For locations where TPH is the sole constituent, a cleanup strategy will be considered based on the findings of a soil treatability study, and the soil will be cleaned to the 5 milligrams per kilogram LUT value?. Based on findings of the Soil Treatability Studies, it was concluded that TPH analytical limitations plus the presence of naturally occurring organic materials at the LUT level (5 may make cleanup to this level very difficult. Biotreatment to accelerate natural degradation of these constituents may prove useful, however DTSC retains authority and jurisdiction to direct additional actions over any areas where monitored natural attenuation or biotreatment is part of the proposed remedy. DTSC will consider the cleanup actions ability to achieve the cleanup values and timeliness to complete cleanup when evaluating cleanup methods. 43.Section 0.6.1, Page D-37: The past paragraph indicates that commercial laboratories have indicated to DOE that they could meet USEPA Laboratory A MDCs, but would have difficulty achieving Lab MDCs. While no documentation is cited, it is noted that Laboratory MDCs are an analytical target, and USEPA recommended a process for procuring analytical laboratories that includes a rigorous demonstration for achieving measurement quality objectives and programmatic needs (HGL 2012). 44. RMHF Leach Field Bedrock Excavation, page 0-62: There is no mention of using overburden soil as backfill as stated previously in the document. This should be addressed in the document. Page 7 of 7