Four Risk Characterization Issues and a Practice Tip from Fiscal Year 2016 NOAF Review 

By: Crista J. Trapp, Human Health Risk Assessor, The Vertex Companies, Inc. and LSPA's Loss Prevention Committee  

Annually, the LSPA's Loss Prevention Committee (LPC) reviews the previous year's Notice of Audit Findings (NOAFs) from MassDEP.  This year the LPC downloaded FY2016 audit and enforcement notices from MassDEP’s eDEP file viewer.  These materials included Level 1 and Level 2 NOAFs, Notices of Noncompliance (NONs), Administrative Consent Orders, and Administrative Consent Orders with Penalties.  In all, over 500 files were downloaded and screened with filtering software. Each file was then assigned to at least one of several categories of concern. A summary of MassDEP findings, observations, and practice tips are presented below for this specific category of concern.

The LSPA’s Loss Prevention Committee (LPC) continues its annual review of Notice of Audit Findings (NOAFs) issued by the Massachusetts Department of Environmental Protection (MassDEP) with a review of NOAFs that discuss Risk Characterization. The protection of health, safety, public welfare, and the environment is one of the main purposes of the Massachusetts Contingency Plan (MCP). The MCP allows remediation decisions to be based on the risk posed by site conditions, as opposed to requiring cleanup to background in all instances. Accordingly, it is extremely important that Licensed Site Professionals (LSPs) include Risk Characterizations that are sufficient to support site cleanup decisions and, at the time of a Permanent Solution Statement (PSS), adequately support the conclusion that site conditions are protective of health, safety, public welfare, and the environment.

The LPC reviewed a total of nine NOAFs and one Administrative Consent Order (ACO) that were categorized as pertaining to Risk Characterization. All of the nine sites receiving NOAFs were issued NONs. Provided below are summaries of the issues that MassDEP noted at these sites.

Please note that this article describes issues identified by MassDEP. The LPC author has not independently reviewed the underlying documents.

Site Information Required for Risk Characterization (310 CMR 40.0904)

Gaps in the site information and the evaluation of contaminant nature and extent evaluation can lead to great uncertainty in the Risk Characterization. In other words, the conclusions of the Risk Characterization are only accurate and defensible if the nature and extent of the release has been properly defined and all relevant media and migration pathways have been considered. Three NONs were issued due to failure to define the extent of the release in all media or failure to adequately characterize the disposal site. All three NONs involved failure to adequately evaluate groundwater.

The first NON was issued for a PSS that was submitted to document the assessment and remediation of a release of fuel oil from a 6,000-gallon storage tank located in the basement of the site building. Remediation consisted of the excavation and disposal of soil performed as a Limited Removal Action, in-situ treatment of petroleum contaminated soil, and post-remediation soil sampling. Groundwater was not assessed for potential petroleum impacts despite water being observed in six shallow hand-dug excavations and on the surface of the dirt floor under the tank. Observations indicated that tank overfills likely occurred and holes were seen in the tank during removal activities. The NON indicated that the assessment of the potential petroleum impacts to groundwater was necessary to ascertain the extent of the release and to determine if potential indoor air impacts exist. Depending on the concentration of dissolved petroleum constituents in groundwater, if present, and in soil, indoor air samples may also be necessary. MassDEP noted that failure to define the extent of the release in all media is a violation of 310 CMR 40.0904(2)(a).

The second NON was issued for a Phase II and PSS that failed to include the bedrock aquifer in the evaluation of the extent of groundwater contamination at the site. Additionally, chlorinated volatile organic compounds were identified in soil near the water table above MassDEP’s S-1/GW-2 standard. MassDEP determined it was unable to verify if the current or prior standards for risk levels were met for the site because of the lack of adequate groundwater sampling. MassDEP stated that although the soil remediation performed at the site near the water table may have reduced vapors in the shallow layers of groundwater, it was possible that dense non-aqueous phase liquid levels could still be present at the site on bedrock, in the rock matrix, or in areas of back diffusion, and thus act as a continuous source. Well placement failed to provide “good” data required for accurate groundwater flow direction. According to the NON, the LSP opined that groundwater flowed south but this was contrary to the northerly directions opined by others in reports for subsequent release tracking numbers issued at the site and in the immediate vicinity. MassDEP decided that the performance standards of both the Phase II and the PSS had not been met due to the presence of TCE and tetrachloroethene (PCE) co-located in soil near the building, the high levels of TCE detected in soil gas samples outside the building, and the failure to fully evaluate the deep groundwater aquifer with respect to the full extent of contamination, groundwater flow characteristics, and contaminant migration along former and current preferential pathways, in light of an unidentified source(s).

The third NON was issued for a PSS in which the LSP opined that a particular water sample was not representative of true groundwater, but rather perched rainwater and surface runoff migrating onto the site from an adjacent property that operates as a drop-off bottle, can, cardboard, paper, and plastic recycling center. In the NON, MassDEP wrote that if, as stated, surface water runoff from the adjacent property was the source of the soil and groundwater contamination at that sample location, then by extension the same contaminated overland surface flow would also have impacted the soil or groundwater located upgradient of that particular sample location, between it and the adjacent property. Because soil and groundwater located upgradient of the sample location in question had not been evaluated for the presence of Contaminants of Concern (COCs), there was insufficient information in the Method 3 Risk Characterization to conclude that the site had achieved a condition of No Significant Risk (NSR), and that a PSS with No Conditions could be filed. Additionally, if contamination at the site was in fact the result of an upgradient source, then the parameters selected for laboratory analysis (e.g., petroleum and metals) may have been insufficient to fully characterize the potential threat to human health caused by the runoff without first sampling the runoff and the soil and groundwater located between the site and adjacent property for other commonly identified contaminants from similar sources (e.g., chlorinated solvents, polychlorinated biphenyls, etc.).

Identification of Exposure Points (310 CMR 40.0924)

Two NONs were issued due to failure to identify appropriate Exposure Points. In accordance with the MCP, all potential Exposure Points must be identified and described in the documentation of the Risk Characterization. Existing water supply wells and monitoring wells must be used to represent current or potential groundwater Exposure Points, and consideration must be given to the identification of Exposure Points that may be located at a distance from the original source of the release, particularly when the migration of oil and/or hazardous material (OHM) may result in Exposure Points in addition to those identified under current conditions.

One of the NONs issued for violation of 310 CMR 40.0924 was for a PSS that documented a condition of NSR at a site with respect to an underground storage tank (UST) release. The PSS relied upon a Method 1 Risk Characterization to evaluate risk to human health, public safety, public welfare, and the environment. According to the NON, the PSS failed to identify a former potable supply well as a potential Exposure Point, even though the PSS determined that the UST release had impacted the well.

The other NON was for a PSS that failed to consider off-site migration potential. Additionally, MassDEP stated that groundwater conditions in the vicinity of the site had not been sufficiently evaluated to verify the assertion of NSR to indoor air.

Calculation of Exposure Point Concentrations (310 CMR 40.0926)

Comprehensive and careful analysis of the data is required to develop appropriate Exposure Point Concentrations (EPCs). In developing the EPC for a site, the objective should be to identify a conservative estimate of the average concentration contacted by a receptor at the Exposure Point over the period of exposure. The method used for calculating EPCs should be clearly stated. The Guidance for Disposal Site Risk Characterization (WSC/ORS-95-141) provides specific guidance on developing EPCs, including using spatial and temporal averaging, determining when average concentrations are not appropriate, and addressing “hot spots.”

There was one violation of 310 CMR 40.0926 in the Fiscal Year 2016 NOAFs which was related to the above-referenced potable supply well that was not identified as an Exposure Point. In the NON, MassDEP stated that the PSS failed to identify a conservative estimate of the average concentration for persons in contact with the potable supply well using data gathered during the release investigation. In this case, the PSS provided no EPC for a potable well that was no longer used, but which had not been removed from service or properly decommissioned and therefore could still be a potable source.

Conduct of Environmental Risk Characterizations (310 CMR 40.0995)

Sometimes an Environmental Risk Characterization (ERC) has not been conducted at all or is inadequate. The MCP requires that a Method 3 Risk Characterization be based upon site-specific exposure information and receptor identification (i.e., both human and environmental receptors). Additionally, each current and potential future exposure pathway must be evaluated in a Stage I Environmental Screening (ES) to determine whether it could result in potentially significant exposure. If current or future exposures to contaminants in any media are not ruled out in a Stage I ES, those exposures are considered to be "potentially significant exposures" and a Stage II ERC is required to determine whether a condition of "no significant risk of harm to the environment exists, or has been achieved.”

Two NONs for Fiscal Year 2016 were issued that were related to inadequate ERCs. For one NON, a revised PSS revealed that the site, or a portion thereof, was located within an area designated by the National Heritage & Endangered Species Program as a Priority Habitat and Rare Wildlife area. Surficial soil samples collected at the site contained elevated concentrations of lead, cadmium, extractable petroleum hydrocarbons, and polycyclic aromatic hydrocarbons. A Stage I ES conducted to evaluate potential risk to ecological receptors focused on the ecological effects of exposure to river sediment, but did not include an assessment of the effects to wildlife from potential exposure to contaminants in surficial soil in the riverfront area. The Stage I ES concluded that significant environmental harm was not readily apparent at the site and therefore a Stage II ERC was not warranted. In the NON, MassDEP stated that, according to MassDEP's Guidance for Disposal Site Risk Characterization (WSC/ORS-95-141), if exposure of state-listed threatened or endangered species or species of special concern is possible, then a Stage II ERC should be conducted. Failure to evaluate current and potential future exposure to state­listed threatened or endangered species to surficial soil in the riverfront area of the site was determined to be a violation of 310 CMR 40.0995.

In the other NON, analytical data indicating the presence of one or more volatile petroleum hydrocarbons (VPH) in three of the sediment samples collected along a brook downstream of the site were detected at concentrations higher than those detected in the background sediment sample. In the NON, MassDEP determined that this VPH contamination appeared to be attributable to the site. Although it has not yet been specifically adopted by MassDEP, the NON recommended the use of the sediment screening values and the process used to develop those screening values provided in the report prepared for MassDEP titled “Sediment Toxicity of Petroleum Hydrocarbon Fractions,” dated September 2007. According to MassDEP, this 2007 report indicates that the levels of VPH detected in these sediment samples may pose "potentially significant exposure." In the NON, MassDEP stated that more sediment sampling would be required to provide additional data, including VPH data more representative of current conditions and organic carbon data to generate a more site-specific sediment screening value.  MassDEP notes that this information is necessary to more conclusively determine whether a condition of potentially significant exposure can be ruled out or a Stage II ERC must be performed.

PRACTICE TIP:  Include a Risk Assessor in Project Planning Stages

As discussed at the start of this article, inadequate delineation of the nature and extent of contamination and incomplete site information can lead to uncertainty in the Risk Characterization, and may result in MassDEP rendering the RC invalid. It certainly leads to many NONs related to nature and extent. One way to help avoid this problem is to involve a risk assessor familiar with the MCP early in the project planning stages. During the first project kick-off meeting, a risk assessor can help identify possible human and ecological receptors and how these receptors may be exposed. This will help the project team plan for human health and environmental protection during the site work as well as appropriate types and locations of sampling. The risk assessor should also participate in the development of the site sampling plan to select an adequate sample size for statistical analysis in developing appropriate EPCs and performing background comparisons to eliminate contaminants as COCs. Additionally, a risk assessor can help identify potential hot spots or Upper Concentration Limit exceedances which, if remediated, could help attain a PSS with No Conditions, thereby avoiding an Activity and Use Limitation.