Montana Administrative Register Notice 17-300 No. 12   06/24/2010    
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In the matter of the amendment of ARM 17.56.506, 17.56.507, 17.56.607, 17.56.608 pertaining to reporting of confirmed releases, adoption by reference, and release categorization










            TO:  All Concerned Persons


            1.  On January 14, 2010, the Department of Environmental Quality published MAR Notice No. 17-300 regarding a notice of public hearing on the proposed amendment of the above-stated rules at page 12, 2010 Montana Administrative Register, issue number 1.


            2.  The department has adopted the rule amendments exactly as proposed.  The department has adopted the Montana Tier 1 Risk-Based Corrective Action Guidance for Petroleum Releases with only one general modification.  It has come to the department's attention that on pages 14, 15, and 16 of the proposed Montana Tier 1 Risk-Based Corrective Action Guidance for Petroleum Releases, the explanatory narrative incorrectly indicates that certain numeric screening levels are based on beneficial use (aesthetic) protection.  However, the tables themselves clearly indicate that no screening level is based on beneficial use protection.  Therefore, the department corrected this language in the narrative.  All screening levels are adopted as proposed.


            3.  The following comments were received and appear with the department's responses:


            COMMENT NO. 1:  The commentor opposes the addition of Table D-RCRA Metals Screening Levels on page 12 of Montana Tier 1 Risk-Based Corrective Action (RBCA) Guidance for Petroleum Releases.  The commentor believes further evaluation of petroleum releases based upon exceedances of the aforementioned screening levels could add significant cost to petroleum release site assessments due to the need for additional laboratory analyses.  The commentor states that it is unnecessary to include screening levels for all the RCRA metals when the only metal of concern at petroleum release sites is lead.  The commentor further asserts that, if the cleanup process must include removal of all lead contaminants, it will take longer, require more resources, subject both tank owners and the Petroleum Tank Release Cleanup Fund to additional costs, and that the department is over-reaching by incorporating screening levels for RCRA metals in Montana Tier 1 RBCA Guidance for Petroleum Releases.

            RESPONSE:  The department elected to incorporate screening levels for RCRA metals in Montana Tier 1 RBCA based on historical occurrences of metals in waste oil, and documented past practices of disposing of non-petroleum waste in facility waste oil tanks.  The inclusion of Table D in RBCA does not suggest that all eight RCRA metals need to be analyzed in all sampling conducted in response to all petroleum releases at all facilities.  For example, sampling for RCRA metals is not indicated when the source of contamination is known and it is not from a used/waste oil tank.  When analytical results from screening samples at sites with known or suspected waste oil contamination do not detect RCRA metals above the Table D screening levels, additional sampling for the listed RCRA metals will not be required. Upon exceedance of a screening level for one or more RCRA metals, the department must be consulted to determine whether further evaluation for RCRA metals is appropriate.

            Table A in Montana Tier 1 RBCA states RCRA metal analyses are required when assessing facilities contaminated with used (waste) oil or unknown oil sources.  RCRA metals are not normally anticipated at typical petroleum storage tank facilities, and the department does not require metal analyses when there is no indication that metals may be present.  Previous versions of RBCA contained these testing requirements, but did not specifically list screening levels for RCRA metals, now listed in Table D.  The department finds it necessary to list screening levels for the eight RCRA metals in the Montana Tier 1 RBCA document so that when RCRA metals are analyzed at used/waste oil sites or at sites contaminated with oil from unknown sources, the screening levels are available in one place.


            COMMENT NO. 2:  The commentor objects to the department's representation that modeling parameters used to establish screening levels are based on statewide conditions.  As an example, the commentor refers to the department's statements that the Montana Tier 1 RBCA Guidance for petroleum releases provides risk-based screening levels relied upon by the department to confirm the existence of a release of petroleum, and RBCA sets soil screening levels using input modeling parameters "representative or estimated statewide conditions."  The commentor points out that the model actually relies on top horizontal boundary percolation rates of 2.5x10-4 meters per day, and that this percolation rate corresponds to Kalispell, which is not representative of estimated statewide conditions.  See Montana Tier 1 RBCA, Appendix D, Soil Leaching to Groundwater Modeling.  The commentor then points out that percolation rates were examined for six Montana cities (Billings, Great Falls, Havre, Helena, Kalispell, and Miles City), which resulted in a range of rates from 8.3 cm/yr (Kalispell) to 3.8 cm/yr (Helena).  The department chose the most conservative of these percolation rates, not a rate that is representative of statewide conditions.  The commentor states that this is one of many modal parameters for which a conservative parameter was used to arrive at a tabulated risk-based screening level and not a parameter that is "representative of estimated statewide conditions."  The commentor states that "if the department is representing to the public that they are using parameters representative of estimated statewide conditions, then that, in fact, is what they should be using."  The commentor agrees that parameters should be representative of statewide conditions so that more representative screening levels may be developed and used to screen and address petroleum contamination in the state.

            RESPONSE:  It is true that the current and proposed Montana Tier I RBCA screening levels were established using input modeling parameters representative of estimated statewide parameters.  In other words, the department estimated the data for the various conditions that exist around the state.  However, this does not mean that the department then averaged the estimated data.  Rather, to establish the screening levels, the department used the most protective estimates to avoid underestimation of the risk to receptors.  Only by using this conservative methodology can the screening levels achieve their purpose--to provide a level of contamination that can be applied to a site anywhere in the state to determine that there is not an unacceptable risk at the site.

            It is true that the risk at some sites will be overestimated.  However, when appropriate, and with department approval, petroleum storage tank owners and operators may use parameters that are tailored to specific site conditions to evaluate risks.  See ARM 17.56.607(4)(b)(ii) of these rule amendments.


            COMMENT NO. 3:  The commentor opposes using screening levels for carcinogens that are based on 1x10-6.  The commentor states that the department is developing a rule that is more stringent than the statutory requirement at 75-5-301, MCA, that state water quality standards for protection of human health must not exceed 1x10-5 for carcinogens other than arsenic.  The commentor states that the department has provided no evidence demonstrating that chemical constituents found in petroleum products produce a cumulative carcinogenic risk.  The commentor recommends that the department establish screening levels based on a risk level of 1x10-5 for carcinogens so as to be consistent with 75-5-301, MCA, and avoid risking level challenge of the proposed rules.

            RESPONSE:  When cleanup levels are calculated, ARM 17.56.607(4)(b) allows for an increased cumulative cancer risk level of 1x10-5.  This is consistent with 75-5-301, MCA, which provides that state water quality standards for protection of human health must not exceed 1x10-5 for carcinogens other than arsenic.  However, at the initial stage of evaluating a site, it is appropriate to use screening levels based on a 1x10-6 risk level to determine whether a site warrants further evaluation or response because at the time that screening is done, it is probable that the department will not know how many carcinogenic substances exist at the site.  Therefore, comparing each hazardous or deleterious substance against a 1x10-6 screening level will help ensure that the cumulative risk from the site does not exceed 1x10-5 and is consistent with acceptable risk levels established by statute.


            COMMENT NO. 4:  The commentor believes the department is attempting to establish guidance for "vapor intrusion" which has not yet been established by the Environmental Protection Agency for potential releases of petroleum.  The department should not establish standards that are more stringent than what the federal guidance may be.  This could result in huge costs to the Petroleum Tank Release Compensation Fund through increased sampling and analysis requirements. The commentor recommends that the department not establish vapor intrusion standards until the EPA has published its guidance to the states.

            RESPONSE:  The proposed RBCA does not set vapor intrusion standards.  The department currently uses inhalation risk factors to determine whether the vapor intrusion exposure pathway is complete and, if so, whether it may pose an unacceptable risk to human health.  A complete pathway means that humans are exposed to vapors originating from site contamination, either from volatilization from impacted soil, impacted ground water, or both.  Calculations to assess the risks to human health from this exposure pathway have been incorporated in previous versions of RBCA.  However, the method has been modified in the current version to be consistent with EPA's approach presented in "Risk Assessment Guidance for Superfund, Volume I:  Human Health Evaluation Manual (Part F, Supplemental Guidance for Inhalation Risk Assessment) (EPA, January 2009)."


Reviewed by:                                     DEPARTMENT OF ENVIRONMENTAL





/s/ James M. Madden                          By:  /s/ Richard H. Opper                        

JAMES M. MADDEN                                   RICHARD H. OPPER, DIRECTOR

Rule Reviewer


            Certified to the Secretary of State, June 14, 2010.


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