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L. McMahan <br /> June 15, 2018 <br /> Page 3 of 3 <br /> Regardless, PFAS are identified COPCs, and their absence from the GMWP will <br /> hinder a HHRA. HERO reiterates our original comment and recommend adding <br /> PFAS to the analytical suite for samples collected at Site 3. <br /> 4. Response to HERO's May 1, 2018 General Comments #6 and #7 — HERO <br /> recommended providing information on how the groundwater monitoring results <br /> will be used in the future. HERO also recommended that the method detection <br /> limits (MDL) not exceed risk based screening levels to ensure the results could <br /> be used in a future HHRA. <br /> The Port of Stockton's response states that the monitoring results will be used to <br /> monitor the extent of VOCs and TPH in groundwater and may be used in the <br /> future for the remedial investigation (RI)/ feasibility study (FS). The 2018 third <br /> quarter monitoring results are not planned to be used for risk assessment. <br /> HERO considers the Port's response to be internally inconsistent. In order to <br /> complete the RI/FS, the data will need to be usable for a risk assessment. <br /> HERO strongly recommends ensuring the groundwater data from this sampling <br /> event be usable for a risk assessment. Please ensure that the MDLs do not <br /> exceed risk based screening levels. HERO recommends using the more health <br /> protective between DTSC's HHRA Note #3 screening levels <br /> (http://www.dtsc.ca-gov/AssessingRisk/ui)load/HHRA-Note-3-January-2018 pdf) <br /> and US EPA's regional screening levels (httr)s://www.epa..qov/flsk/regional- <br /> screening-levels-rsls-generic-tables). <br /> CONCLUSIONS: <br /> HERO has reviewed the responses to HERO's May 1, 2018 comments on the <br /> Groundwater Monitoring Work Plan for Rough and Ready Island, Port of Stockton, as it <br /> relates to human health risk assessment. HERO has found the Port of Stockton's <br /> comments to be unacceptable. We recommend addressing our comments prior to <br /> finalizing the work plan. We look forward to your response. <br /> REFERENCES: <br /> Geosyntec (2017) "PFAS Groundwater Sampling Work Plan, Site 3, West Complex, <br /> Rough and Ready Island, Port of Stockton. Stockton, California." December. <br /> Reviewed by: Valerie Hanley, Ph.D. <br /> Staff Toxicologist <br /> Concur by: Thomas Booze, M.S., Ph.D. <br /> Senior Toxicologist, DSMO <br />