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ASPECT CONSULTING <br />ES-2 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025 <br /> First IA, 2013-2014: Permanent removal and off-site disposal of approximately <br />38,450 tons of contaminated material from the Upland Area. Collection, treatment, <br />and discharge of more than 5.6 million gallons of groundwater, including water <br />with free-phase petroleum product, and confirmational groundwater monitoring <br />following remedial excavations (2014-2016). <br /> Second IA, 2020. Permanent removal and off-site disposal of an additional <br />17,610 tons of contaminated material from the Upland Area. Collection, treatment, <br />and discharge of an additional 2.28 million gallons of groundwater. Inspection, <br />cleaning, and plugging of 19 shoreline pipes. Removal and off-site disposal of <br />252,000 tons of crushed material (CM) and associated monitoring of groundwater <br />pH. The CM, consisting of concrete and brick debris from demolition of mill <br />structures, was previously graded over a portion of the Upland Area where <br />pavement had been removed <br /> Third IA, 2021-2023. Grading and construction of a low-permeability cap, <br />designed to reduce surface water infiltration. Installation of subgrade utilities <br />during earthwork for cap construction. Construction of a new stormwater drainage <br />and conveyance system integrated into the environmental cap, a new chitosan- <br />enhanced sand filtration treatment system for stormwater, and reconstruction of <br />existing stormwater outfalls A and M for discharge of the treated water to the East <br />Waterway. Installation of upgraded security fencing. <br />The three completed IAs successfully removed most of the identified contaminant source <br />materials and then constructed a low-permeability environmental cap to restrict infiltration <br />through soils containing residual low-level contamination. <br />Remedial Investigation <br />Following the removal of contaminated materials during the First and Second IAs and CM <br />removal, concentrations of contaminants in soil are below criteria based on industrial <br />direct contact but some are above conservatively calculated values based on the protection <br />of leaching to groundwater. Soil with total petroleum hydrocarbons (TPH) or PCBs <br />exceeding criteria for the protection of groundwater was left in place beyond practicable <br />excavation limits in localized portions of the Upland Area, including soil located beneath <br />remaining concrete foundational elements and at the top of the shoreline bank. The third <br />IA will reduce infiltration resulting in reduced contaminant leaching to groundwater. <br />Although TPH contamination remains in soil beneath the distribution warehouse at <br />concentrations that exceed criteria for unrestricted land use, the direct contact exposure <br />pathway is incomplete because of the presence of the warehouse building. Residual <br />TPH in soil beneath the warehouse has not resulted in accumulation of free product <br />nor caused dissolved-phase concentrations exceeding groundwater cleanup levels. <br />Hydrocarbon concentrations measured in indoor air and sub-slab soil gas may pose a <br />vapor intrusion risk for potential future commercial or unrestricted use of the warehouse, <br />but not for the current industrial use.