NCD003162542_Badin Business Park_Corrective Action_20220815

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ATTACHMENT 1
Former Ball Field Area Screening–Level Ecological Risk Assessment
Badin Business Park Badin, North Carolina NCD 003 162 542
The “Former Ball Field Area Screening–Level Ecological Risk Assessment” (April 26, 2021) has
been reviewed in support of an assessment of the completeness for decision making of the screening–level ecological risk assessment (SLERA) for the Former Ball Field Area (the Site). The following recommendation is made:

Using the lines of evidence outlined herein and in Section 4.0 (Lines of Evidence Preview), revise the Scientific Management Decision Point (SMDP) to conclude that ecological risks are negligible and, therefore, further investigation or remediation of the Site on the basis of ecological risk is not needed.

Based on independent review of the SLERA, ecological risk to terrestrial receptors at the Site is minimal and acceptable. This determination is supported by an adequate data set (both in terms of geographic coverage of samples and number of samples), an extensive chemical of concern (COC) list, and a conservative comparison of data to media-based screening levels. However,
the Former Ball Field Area Screening–Level Ecological Risk Assessment, dated April 26, 2021
(Ball Field SLERA), concludes that “the information indicates a potential for adverse ecological effects and a more thorough assessment is warranted.” This conclusion appears to be inconsistent with the general findings of the SLERA and the lines of evidence presented in Section 4.0 (Lines of Evidence Preview). While additional analysis of toxicity studies and
refinement of the toxicity reference values could be conducted in Step 3a of the ecological risk
assessment (ERA) process as proposed in the Ball Field SLERA, it appears that sufficient data and information are currently available to finalize the SLERA as–is. Discussion points that support finalization of the ERA process are as follows: 1) data gaps were not identified; 2) data are of sufficient quality and quantity for decision making; 3) there is no connection between Site
activities and detected concentrations at the former ball field (i.e., there is no indication of a
source); 4) isolated exceedances of COCs are not indicative of Site–wide contamination (detected at low concentrations and/or infrequently); and 5) COCs are not present at concentrations that would cause ecological risk. These discussion points are consistent with the lines of evidence presented in Section 4.0 (Lines of Evidence Preview).

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ATTACHMENT 2
Screening Level Ecological Risk Assessment Report for the Alcoa/Badin Landfill
Badin Business Park Badin, North Carolina NCD 003 162 542
A technical review has been conducted of the “Screening Level Ecological Risk Assessment
Report for the Alcoa/Badin Landfill” (December 2021). Below are General and Specific Comments based on the technical review of the document. GENERAL COMMENTS
General Comment 1. The screening level ecological risk assessment (SLERA) (Steps 1 and 2) presents select elements of a conceptual site model (CSM) and an analytical data screening process, but it does not present a comprehensive CSM which connects potential sources (historical and current), media of interest, transport mechanisms, exposure routes, and
potential ecological receptors; nor does it include a complete data screening (e.g., data analysis)
using the available analytical data. In addition, there is not a presentation of data gaps or a complete evaluation of data quality. Revise the Screening Level Ecological Risk Assessment Report for the Alcoa/Badin Landfill, dated December 2021 (Landfill SLERA) to: (1) present a comprehensive CSM; (2) present the basis for the chemicals of potential concern (COPCs), and
identify which sample locations were included in the SLERA data set; (3) develop a data gaps
section that addresses data gaps in the nature and extent of sampling; (4) identify major uncertainties in the sample coverage and/or data quality issues; and (5) present a basis for Step 3 of the ecological risk assessment process.
General Comment 2. The Landfill SLERA uses sample data from various reports (see
Appendix E, Excerpts from Published Reports – Sampling Location Maps) but does not present a figure that consolidates all sample locations and connects them with the potential source areas (historical and/or ongoing) and ecological receptors. Provide a figure or figures which depict the locations of all samples evaluated in the Landfill SLERA to demonstrate that sample coverage in
the areas of interest (both source areas and those areas that reflect potential COPC transport or
accumulation) is sufficient. It is noted that Figure 2 (Site Features Map) could be used as a base figure. General Comment 3. There is a 2008 statewide fish consumption advisory in place for
mercury, and as of February 2009, a fish consumption advisory is in place for Badin Lake (both
Stanly and Montgomery counties) for polychlorinated bipnenyls (PCBs). It is unclear if contamination from the Alcoa/Badin Landfill (also known as Solid Waste Management Unit No. 2) and the adjacent Little Mountain Creek and floodplain (the Site) could contribute to the need for the fish advisories. Address the potential for the Site to contribute COPCs to fishable water
bodies included in the fish consumption advisories.
General Comment 4. The SLERA does not include a lines–of–evidence analysis for each exposure area, including a comparison of Site data to background concentrations, analysis of
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frequency of detection of COPCs, and an analysis of the applicability of the ecological screening levels. For example, the text states in Section 3.3.3, Screening Criteria, that few aquatic
invertebrates were observed in Little Mountain Creek and, therefore, ecological screening values
based on protection of benthic invertebrates may not be applicable. However, this discussion should be expanded to include a review of the aquatic resources in Little Mountain Creek, applicable receptors, the outcome of the screening, data gaps and a recommendation to focus the Step 3 analysis on Little Mountain Creek. Revise the Landfill SLERA to include a lines–of–
evidence analysis for each exposure area.
SPECIFIC COMMENTS
Specific Comment 1: Section 2.1.2, Regional Ecological Summary, Pages 8-13 and Section 2.1.3.5, Habitat Evaluation, Pages 22-25. Section 2.1.2 presents information on the ecoregion, vegetation communities, and an assessment of protected species. Section 2.1.3.5 presents information relevant to the Site area; however, there is no recommendation regarding what species/habitats should be considered in the next phases of the ecological risk assessment
process. Identify if special status species or critical habitats could be impacted by Site
contaminants and if additional sampling is needed to address risk to these species or habitats. Specific Comment 2: Section 2.2, Fate and Transport, Pages 25-27. The Landfill SLERA evaluates surface soil, surface water and sediment data, but does not clearly explain how these
media were contaminated and if there are any on-going sources of contamination. The text states
that the landfill and releases from equipment at nearby electrical substations are potential sources, but it is unclear how historical operation of the landfill specifically lead to releases of contaminants. Revise the Landfill SLERA to explain how operations at and/or releases from the landfill and electrical substations resulted in contamination of soil, surface water, and sediment.
In addition, clarify if there are any on-going sources of contamination.
Specific Comment 3: Section 2.2, Fate and Transport, Page 26. The first full paragraph on page 26 is the first place where Site-related COPCs are presented (cyanide, fluoride, metals, semivolatile organic compounds and PCBs) based on industrial waste managed
at the landfill and the nearby electrical substations. While there is some discussion of
contaminants identified during previous investigations on page 8, there is no clear presentation of all COPCs expected based on the Site history. Revise the Landfill SLERA to include a comprehensive discussion of COPCs based on the Site history and past investigations.
Specific Comment 4: Section 2.2, Fate and Transport, Pages 26-27. The last paragraph on
page 26 states that the seep collection system is effective, and the landfill is “not believed to represent an active source of dissolved phase COPCs to the floodplain.” However, the text subsequently states that “Groundwater discharge to surface water occurs in the floodplain” and that “the groundwater within the floodplain has the potential to represent an active source of
dissolved phase COPCs.” These cited statements appear to contradict one another, and several
issues were identified: (1) the source of COPCs in groundwater is unclear; (2) it is unclear if there a defined contaminant plume; (3) it is unclear under what conditions groundwater discharges to surface water (e.g., following heavy rain events); and, (4) it is unclear where
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groundwater discharges specifically (e.g., upwelling into the wetlands). Revise Section 2.2 to address each of these issues by including a discussion of the sources, nature, and extent of
groundwater contamination. In addition, describe the hydrogeology of the Site and evaluate the
mechanism of groundwater-to-surface water discharge. Finally, identify any data gaps and uncertainties in the understanding of the hydrogeology of the Site. Specific Comment 5: Section 2.3.1, Receptors, Page 28. Section 2.3.1 presents a detailed
discussion of receptors, but does not discuss where these receptors are relevant. For example, it
is unclear where there is relevant terrestrial habitat since the landfill has been covered and is “not believed to represent an active source of particulate and dissolved phase COPCs.” Add a discussion in Section 2.3.1 that clearly identifies the areas being investigated in the SLERA and which receptors are relevant in the various exposure areas.
Specific Comment 6: Section 3.3.1, Data Evaluation, Pages 32-33. This section describes the number of samples collected from various investigation and reporting efforts. The summary of the sample numbers per media is somewhat misleading. For example, the text states that groundwater data are available from between 1 and 80 samples depending on the analyte
analyzed; however, Table 7, Groundwater Screening and Hazard Calculation, shows that only 1
to 4 samples were analyzed for the majority of analytes. Twenty–seven and 80 samples were analyzed for cyanide and fluoride, respectively. Revise the text to more accurately reflect the number of samples evaluated in the SLERA.
Specific Comment 7: Section 3.3.1, Data Adequacy, Page 38. The evaluation of the
adequacy of the sample data should be expanded, both in terms of spatial coverage across the exposure areas and data quality. The screening methodology requires an assessment of the method detection limits, but the SLERA also should present an evaluation on the strength of the data set to represent ecological exposure. For example, Section 3.3.1 states, “soil samples were
not analyzed for all constituents identified as COPCs (HQ [hazard quotient] > 1).” This
discussion should be expanded to clarify to which COPCs the statement is referring, why the CSM indicates that exposure to these COPCs may be occurring, and if/where additional sampling is warranted. Expand Section 3.3.1 to evaluate the quality of the data, spatial coverage, representativeness of the data set for ecological exposure, and identify data inadequacies.
Specific Comment 8: Section 3.4, Scientific Management Decision Point (SMDP), Page 40. The Scientific Management Decision Point (SMDP) should be expanded to recommend the next steps in the ecological risk assessment process. This could be organized by exposure area and could include recommendations such as additional sampling and analysis for a limited COPC
list, and further evaluating if protected species should be considered in the next phase of the risk
assessment. Expand the SMDP to include recommendations for the Step 3 ecological risk assessment by exposure area. Specific Comment 9: Tables 3, 5, and 7. Table 3, Sediment Screening and Hazard
Calculation, lists nine sediment samples analyzed for PCBs, all results are listed as not detected;
however, a total PCB value of 0.0927 milligrams per kilogram (mg/kg) is listed in the table. Table 5, Surface Water Screening and Hazard Calculation, identifies 19 samples as being non-detect for PCBs, but there is a total maximum detected value of 0.0035 mg/kg listed in the table.
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Similarly, Table 7, Groundwater Screening and Hazard Calculation, lists three samples as non-detect for PCBs, but there is a total maximum detected value of 0.00175 mg/kg listed in the
table. It is unclear how these total PCB concentrations were derived. Revise the Landfill
SLERA to discuss the derivation of the total PCB concentrations in sediment, surface water, and groundwater. Specific Comment 10: Table 4 and Table 6. Based on a review of Table 4, Sediment
Congener Screening and Hazard Calculation, and Table 6, Surface Water Congener Screening
and Hazard Calculation, surface water and sediment data were analyzed for PCB Aroclors and congeners, yet there is no discussion of these data in the Landfill SLERA. The following issues were identified: (1) it is unclear what the congener analysis indicates regarding how the PCBs are weathering; (2) it is unclear if dioxin-like congeners are present; (3) it is unclear if there is a
potential transport mechanism for PCBs to surface water bodies where they can accumulate in
biota; (4) no discussion on the solubility of PCBs in water is presented; (5) it is unclear if the substations represent on-going sources of PCB contamination; and, (6) it is unclear if total PCB data should be discussed in Section 3.1.3, Summed Concentrations. Revise the Landfill SLERA to include an analysis of the PCB Aroclors and congener data, and further develop the CSM
specific to PCBs (i.e., evaluate the source(s), transport mechanisms, and understanding of
concentrations in the exposure areas). As part of this, ensure each of the aforementioned issues is addressed.