ESA: Large Trucking Facility

Project Description

The nature of the business at the project site required storage of bulk motor oil, hydraulic oil, waste oil, antifreeze, batteries, and smaller quantities of hazardous materials. The subject property historically operated numerous underground storage tanks (USTs), production water wells, underground injection control (UIC) structures, and cesspools. Prior to operation as a trucking facility, the subject property was used to manufacture pipe and finished materials were shipped via an adjacent railroad spur. Historical operations as a pipe manufacturer resulted in impact from polychlorinated biphenyls (PCBs) associated with large power transformers and chlorinated solvent impact to the Troutdale Aquifer located 50 feet below land surface (BLS).

A focused Phase II Environmental Site Assessment (ESA) conducted at the site included a geophysical survey over the majority of the site using primarily a magnetometer, a ground penetrating radar (GPR) system, and electromagnetic tracers and pipe locators. The geophysical survey helped to confirm and identify the location of potential UST cavities, former excavations, dry wells, cesspools, septic tanks, utility lines, abandoned wells, and to provide clearance for push probe sampling locations. In late 2007, 28 push probe borings were installed near areas of concern or Recognized Environmental Conditions (RECs) identified by the geophysical survey and in the Phase I ESA to facilitate sample collection activities. Push probe borings were placed in the areas of former UST cavities, identified sumps and dry wells, near the wash rack, adjacent to the paint booth, within the footprint of the former pipe manufacturing building, and in the area of former sandblasting and a magnetic anomaly (i.e., possible buried drum).

The results of the focused Phase II ESA documented soil and groundwater impact predominantly by diesel-range and heavy oil-range total petroleum hydrocarbons (TPH), and to a lesser extent, polynuclear aromatic hydrocarbons (PAHs), gasoline-range TPH, volatile organic compounds (VOCs), chlorinated solvents, and metals. PCBs were not detected in any of the soil and groundwater samples analyzed. Despite minimal human-health risks associated with residual contamination, consideration was given to in-place treatment or removal of “source” soils in the vicinity of the service area sump, wash rack, and loading dock dry well to reduce concentrations of detected contaminants in those areas. Detected contaminants in those areas represent an environmental liability for the subject property associated with future facility improvements (e.g., future soil excavation associated with subsurface and near-surface utility and infrastructure construction projects), apart from regulatory review and opinion. Upon completion of a Feasibility Analysis, which evaluated four (4) potential remedial alternatives for contaminant reduction in source areas, the potential data gaps and/or areas requiring additional characterization were recognized near the service shop sump, near the wash rack, and in the north portion of the site near several push probes.

In addition to the data gaps associated with these areas, new information was provided following completion of the focused Phase II ESA that identified the location of former PCB containing transformers at the subject property. This area, and other areas of concern to the potential buyer, were then added to the scope of an expanded Phase II ESA of the subject property. In early 2008, 17 additional push-probe borings were installed at the subject property. As part of the expanded investigation, soil samples were collected from each of the soil borings. Groundwater samples were collected from 10 of 17 push probe borings as agreed upon by the potential buyer. As further quantified by completion of the expanded Phase II ESA, the subject property has apparently been impacted by leaking infrastructure associated with disposal sumps (north shop area), a diesel spill, and improper handling, management and control of petroleum products and petroleum waste. Contaminants in soil appeared to be limited to primarily diesel-range and heavy oil-range TPH. Low concentrations of a few TPH related VOCs, tetrachloroethene (PCE), and PAH compounds were also identified.

Groundwater contamination appeared to be limited to diesel-range TPH, heavy oil-range TPH, and PAHs west and northwest of the service shop, presumably associated with dry well storm sewer system infiltration in this portion of the subject property. Minimal VOC and PCE contamination was detected in groundwater in this area. However, low levels of PCE in groundwater appear to extend over much of the south and southwestern portions of the site beneath the footprint of the former pipe manufacturing building.

To evaluate potential environmental liability and human-health risk posed by detected contamination in soil and groundwater, documented contaminant concentrations were compared to the risk-based concentrations (RBCs) developed by the Oregon Department of Environmental Quality (DEQ) in the guidance document titled Risk-Based Decision Making (RBDM) for the Remediation of Petroleum-Contaminated Sites. Where RBCs were not available, EPA’s Region 9 Preliminary Remediation Goals (PRGs) were used as reference levels. Based on current and likely future land use and zoning of the subject property, appropriate non-residential RBCs were used for potentially complete exposure pathways and receptor scenarios.