Remediation and Redevelopment Division Michigan Department of Environmental Quality RRD OPERATIONAL MEMORANDUM NO. 2 FREQUENTLY ASKED QUESTIONS July 2005 Addendum This document is an addendum to the RRD Operational Memorandum No. 2 Frequently Asked Questions of February 2005. Terms defined in the Operational Memorandum have the same meaning when used in this document. Chromium VI (Hexavalent Chromium) The MDEQ has reviewed alternative methods available for analyzing hexavalent chromium (other than those already designated in RRD Operational Memorandum No 2, Attachment 1). The MDEQ has concluded that the following methods are considered appropriate for hexavalent chromium analysis, and are approved, provided that analysis conforms to the provisions/stipulations discussed in the following paragraph: • For water, methods 7196A chromium, hexavalent (colorimetric), and 7197 chromium, hexavalent (Chelation/Extraction) • For soil, methods 3060A/7196A and 3060A/7197 The approval for method 7196A chromium, hexavalent (colorimetric) is based upon the provision of method 7196A that addresses the concern of interference. The method of standard additions (see Method 7000, Section 8.7) must be used for the analysis of all extracts, on all analyses. Sections 7.3, 7.4, and 7.5 of method 7196a provide specific direction regarding interferences. However, if interference persists after sample dilution, a different method must be used. It should be noted that because of the limited preparation and holding times for hexavalent chromium analysis (24 hours for waters, and 24 hours after extraction for soils), collection of additional samples may be needed if interferences render the initial alternative analytical method unusable. If this does occur, a different method must be used for future sampling at the facility. The prior approval for method 7197 chromium, hexavalent (Chelation/Extraction) is based on equivalent methodologies used in the U.S. EPA Contract Lab Program (CLP), and methods promulgated for use in the CLP are acceptable alternative methods. Lead Fractions The MDEQ has reviewed concerns raised regarding soil fraction sampling for lead and the associated difficulties with sieving dried “clay” soils. This problem has been evaluated to determine if total lead analysis of clay soils, in lieu of separate fine and coarse fraction analysis, is acceptable for comparison to direct contact and soil particulate inhalation criteria. The MDEQ acknowledges that clay soils often consist primarily of fine materials, and therefore has determined that the use of the total lead concentration is acceptable for comparison to direct contact and soil particulate inhalation criteria, if the following conditions are met: 1. The dried soil sample cannot be sieved (as prescribed in the SOP) to separate out any fraction and/or the volume derived from any fraction is too small for analysis (less than one gram); and 2. The field data/sampling information adequately documents that the soils are, in fact, composed primarily of clay. It should be noted that if the field sampling information documents a clay mixture, another sample may need to be collected to provide a representative sample. In addition, if total lead concentrations are used for comparison to criteria, explanation must be provided to the MDEQ as to why fraction analysis could not be conducted. Elevation of Reporting Limits The MDEQ has reviewed elevated reporting limits to provide guidance as to when elevated reporting limits may be acceptable versus when the use of alternative methods to assure the TDLs are achieved becomes necessary. For numerous contaminants standard methods of analysis may not achieve the designated TDLs. In such situations, the applicability of the resulting data needs to be considered in evaluating whether or not it is necessary to achieve the TDL. If it is determined that the TDL must be achieved, sufficient information must be provided to the laboratory to assure the sampling necessary to achieve the TDL will be implemented. Examples of common site contaminant where standard methods 8260 or 8270 may not achieve the TDLs include: ethylene dibromide (EDB), 1, 2-dibromo-3-chloropropane, pentachlorophenol, hexachlorbutadiene and hexachlorbenzene. Of these, EDB, which has an extremely low Part 201 criterion and Part 213 Risk-Based Screening Level (RBSL) for residential drinking water (0.05 ppb), is probably the most common contaminant that is confronted where standard analytical methods do not achieve the TDLs. This contaminant was widely used from approximately 1940 to 1988 as a “lead scavenger” additive to leaded gasoline. (For additional information see “The Potential for Ground Water Contamination by the Gasoline Lead Scavengers Ethylene Dibromide and 1,2-Dicholorethane,” Ronald W. Falta, Ground Water and Remediation Volume 24, No.3/Summer 2004) The following includes examples of scenarios/situations where achieving the TDL would not likely be necessary: • The contaminant is not likely to have been released at the subject facility. For example, if a release of gasoline was known to have occurred after 1988, or is otherwise known to be an unleaded gasoline release, achieving the TDL for EDB would not be necessary. • The pathway or pathways with low-level TDLs are not relevant. For example, if the drinking water pathway is not applicable or otherwise restricted, the GSI pathway would become the most restrictive criteria and a detection limit for EDB that is greater than 0.05 ppb, but less than the GSI criterion (0.2 ppb) for a surface water that is not a drinking water source, may be acceptable (Note: The GSI criterion for the Great Lakes or an inland drinking water source is the same value as the drinking water standard). Similarly, if the GSI pathway is documented not applicable, an acceptable TDL for hexachlorobutadiene and pentachlorophenol would revert to the drinking water RBSLs for these contaminants. It should be noted that whether or not a pathway is deemed applicable does not preclude the necessity of delineating the extent of contamination to residential criteria. • The purpose of the sample is to identify and/or define source areas, and the source area can otherwise be identified and/or defined by other contaminants. Frequently, source areas contain multiple contaminants that can interfere with the detection of specific contaminants to the applicable TDLs, or otherwise mask the presence of a contaminant, even when alternative methods are used. In the case of EDB, for example, the presence of BTEX and other hydrocarbons, especially in concentrations typically found in source areas, would interfere with the detection of EDB such that it may not be possible to detect EDB with any method. The following includes examples of scenarios/situations where achieving the TDL would likely be necessary: • The purpose of the sample or samples is to delineate the extent of contamination to residential criteria or RBSLs. For example, to define the leading edge of dissolved- phase plume from a leaded gasoline release, it is necessary to achieve the low-level TDL for EDB. However, for such circumstances, there should not be interferences from high concentrations of other hydrocarbons and the low-level TDLs should be achievable. • The samples are for closure verification. Similar to delineation samples, at the point where closure verification samples are collected, concentrations of other contaminants should have diminished to the point where the TDLs would be achievable. Of course, for pathways that are not applicable or otherwise restricted, it may not be necessary to achieve the low-level TDL. • The contaminants of concern (CoCs) for a facility cannot be identified by means other than chemical analysis. For example, if it were unknown whether contamination was from a leaded or unleaded gasoline release, it may be necessary to achieve the TDL for EDB to determine whether EDB is a CoC for this particular facility. • Routine monitoring at the leading edge of a plume or sentinel monitoring. Although it may not be necessary to achieve TDLs for routine monitoring within source areas or within the interior of a plume, it is critical that TDLs be obtained in situations where the purpose of the sample is to monitor the leading edge of a plume or sentinel monitoring of a specific receptor. It is important to recognize that if the TDL must be achieved there may be different collection requirements for an alternative method. Sample collection, preservation, handling, and holding time specifications should be carefully reviewed. Op Memo No. 2 also addresses instances where elevated reporting limits may not be acceptable for contaminants when the TDLs are greater than the most restrictive risk-based criteria. These contaminants are included in Table 6 of Attachment 1. In this situation there are not alternate methods designated to achieve the TDLs and the cause for elevated reporting limits must be carefully evaluated. This may require further actions to reduce interferences (e.g., sample cleanups performed in the laboratory), modifications to lab or field methods, or other actions appropriate to the site conditions. Soil Coring Devices The MDEQ has reviewed documentation submitted for the EnCore™ sample device. The MDEQ acknowledges that there have been scientific studies conducted that demonstrate that the use of this device can result in accurate analytical results for specific volatile organic compounds (VOCs). The MDEQ also acknowledges that there are established procedures for using the device (ASTM D 4547-98). Nevertheless, it is the MDEQs position that if the device is used, site-specific documentation (duplicate or confirmation samples) should be provided to show that the analytical results for samples stored in the EncoreTM device are equivalent to results from samples that are methanol preserved immediately in the field. In particular, this applies if the sample results are used for characterizing the nature and extent of the contamination or for demonstrating compliance with cleanup criteria. (see Operational Memorandum No 2, Attachment 6 page 3 for further details). The MDEQ arrived at this position after reviewing site-specific analytical data that was developed at sites where corrective action was or is being conducted by the MDEQ. This data documents significant discrepancy in analytical results between the two soil sample collection methods referenced above. Accordingly, the MDEQ believes that this requirement is necessary to assure that analytical results are as representative as possible of actual soil contaminant concentrations.
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