3815_PGSF WMVD Pkg 2_Vol 4-2_03.03.2026_BXWA_Certified

ASPECT CONSULTING PROJECT NO. AS190583A-08  MAY 21, 2025 FINAL 31 and Tidewater/Associated Oil Company facilities on K-C property) and south of it (on ExxonMobil/American Distributing Company [ADC] site) to assess whether the historical facilities contributed to petroleum hydrocarbon contamination documented at the CSO line. In the Phase 1 ESA for the mill property (AECOM, 2011), the facilities on the K-C property constituted Recognized Environmental Condition (REC) 2, whereas the facilities on the ExxonMobil/ADC Site constituted REC 1. The 1998 investigation consisted of advancing 17 soil borings; collecting and analyzing soil samples from three borings based on field screening; collecting and analyzing reconnaissance groundwater samples from 14 borings; completing two borings as groundwater monitoring wells inside of the K-C warehouse; and collecting groundwater samples from the wells. Concentrations of TPH and BTEX detected in the three soil samples were well less than unrestricted soil screening levels (TPH less than 150 mg/kg, and negligible BTEX). The highest groundwater concentrations of diesel-range plus oil-range TPH (91,000 to 100,000 µg/L) were detected in groundwater samples collected from two locations adjacent to the CSO line. Those two groundwater samples also contained gasoline-range TPH (327 µg/L and 736 µg/L, respectively), but BTEX concentrations were less than groundwater screening levels for marine protection and VI protection. Much lower groundwater TPH concentrations (nondetect to 430 µg/L) were detected at the two wells located within the footprint of the K-C warehouse. These low, dissolved- phase groundwater concentrations are not indicative of free-phase petroleum product in the vicinity. As such, the data indicated that the source of TPH encountered along the CSO line did not migrate from beneath the K-C warehouse to the north. TPH concentrations exceeding respective screening levels were detected in selected wells located in the area of the Associated Oil Company fuel facilities, and to the west along a Bunker C fuel-oil pipeline that reportedly ran from the slip shoreline to the tank farm. No PAH analyses were conducted in the investigation. The cover letter transmitting the PEG (1998) report to Ecology states, “Based on the results of this investigation, we believe it is impossible to conclude that the free product found in the CSO Line is the result of operations at the Chevron and Tidewater properties, now owned by Kimberly-Clark. In addition, fuel fingerprinting analysis, conducted during the CSO Line repairs, showed a strong correlation between the fuel oil from the CSO Line and the free product recovered from wells at the Mobil/American Distributing site. Based on these results, we believe there is no reason to maintain any link between the bulk plants and the Mobil/American Distributing/CSO problem” (Texaco, 1998). 3.1.9 PCB Decontamination of Substations (1995-2004) K-C removed PCB-containing equipment from the mill between 1995 and 2004 (AECOM, 2011). After cleaning concrete pads beneath electrical transformers 5 and 6 within Screen/Bleach Unit 2, the concrete was found to contain residual PCB concentrations greater than the EPA cleanup level based on wipe sampling. The concrete was removed, and soils beneath them sampled for PCBs. PCB concentrations in the subgrade soils contained 1.4 and 3.4 mg/kg, greater than the 1 mg/kg unrestricted soil screening level and