Rock Fill Layer Management and Maintenance Plan Former BNSF Site 13 Highway 99 Eugene, Oregon

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1 Rock Fill Layer Management and Maintenance Plan 13 Highway 99 Prepared for: Half Moon LLC P.O. Box PBS Project No

2 Rock Fill Layer Management and Maintenance Plan TABLE OF CONTENTS 1.0 INTRODUCTION KEY PERSONNEL SITE INFORMATION Location and Site Description Project Plans Geology and Hydrogeology CURRENT ENVIRONMENTAL CONDITIONS DESCRIPTION OF ROCK FILL LAYER MANAGEMENT OF ROCK FILL LAYER MONITORING OF ROCK FILL LAYER COMPLIANCE... 4 FIGURES Figure 1 Site Location Map Figure 2 Site Plan Figure 3 Cross Section SUPPORTING DATA TABLE Table 1 Key Personnel i Project: No

3 Rock Fill Layer Management and Maintenance Plan 1.0 INTRODUCTION This Rock Fill Layer Management and Maintenance Plan (Plan) has been prepared by PBS Engineering and Environmental Inc. (PBS) on behalf of Half Moon, LLC for use during any future site development activities at 13 Highway 99 in. This plan is intended to provide administrative and technical protocols for inspecting, maintaining, and documenting changes to an existing rock fill layer present at the site that has been shown to prevent exposure to the underlying soil with residual contamination. The measures identified in this Plan are designed to ensure that the rock fill layer remains protective of human health and the environment. This document may be used in conjunction with a Contaminated Media Management Plan (CMMP) prepared for the site. 2.0 KEY PERSONNEL Key personnel for the project are provided in Table 1. Table 1- Key Personnel Company Personnel and Title Contact Information Contractor TBD TBD Owner Paul Bergersen (owner representative) Office: (541) Half Moon, LLC Cell: (541) PBS Engineering and Dennis Terzian, RG Office: (503) Environmental Senior Geologist (Plan Preparer) Cell: (971) SITE INFORMATION 3.1 Location and Site Description The acre property (site or subject property) is listed as tax lots 202 and 203 in Section 36, Township 17 South, Range 4 West of the Willamette Base and Meridian (Figures 1 and 2). The property is bounded to the north by a Burlington Northern and Santa Fe (BNSF) rail line, to the east by Zip-O-Logs (a lumber mill), to the south by Highway 99 North, and to the west by Schnitzer Steel (auto wrecking yard). The site is primarily vacant, with the exception of the eastern portion of the site, which Zip-O-Log leases for lumber storage and loading and employee vehicle parking. The property is zoned I-3 Heavy Industrial. There are multiple paved areas on the site, as well as portable buildings and truck scales, a small building containing a water well, and monitoring wells in the southeast and central portions of the site. A paved access road loops through the central portion of the site, connecting back to Highway 99 North. 3.2 Project Plans No current development plans have been identified for the site. The property is currently being marketed for lease or sale. Zip-O-Log Mills, an adjacent property owner to the east, leases the eastern portion of the site for employee parking and materials storage. 3.3 Geology and Hydrogeology The surface of most of the site is covered by pavement over silty gravel fill or a thin layer of silt overlying silty crushed rock fill. Subsurface soil conditions encountered during previous site assessment activities generally consisted of silts and clay to depths of 8 to10 feet below ground surface (bgs), underlain by gravels to the maximum depth explored at 15 feet bgs. Groundwater was encountered in the boreholes at depths ranging from 3 to 6.5 feet bgs. 2 Project: No

4 Rock Fill Layer Management and Maintenance Plan Suspected fill material, including organic materials, wood pieces, sawdust, and concrete and asphalt pieces, was encountered in numerous soil borings and test pits across the site. Based on field observations, approximately 1 to 2 feet of crushed rock fill is likely to be encountered at locations across the site where the more recent lumber mill operations occurred, with the exception of soil directly underlying former building slab foundations (e.g. former green chain). Crushed rock fill was not encountered in these locations. A cross section depicting an interpretation of site geology based on boring and test pit logs is included as Figure CURRENT ENVIRONMENTAL CONDITIONS Previous site assessment and remedial activities, as well as a summary of site assessment activities performed by PBS in 2012/2013 were summarized in a Site Assessment Report submitted to the Oregon Department of Environmental Quality (DEQ) in July Site contaminants of concern were not identified at concentrations that would pose a risk to construction workers or excavation workers. Residual human health risk at the site is limited to occupational receptors as discussed below. Figure 2 presents historical operational areas identified in the following paragraphs. Dioxins/furans were detected in subsurface locations at areas across the site. The source of these compounds is unknown, but may be related to former lumber mill operations at the site. Concentrations of total dioxins/furans converted to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8- TCDD) toxicity equivalent quotient (TEQ) in shallow soil samples (generally located between 1 to 3 feet bgs) were identified to be in exceedance of the protective risk-based concentrations (RBCs) protective of ingestion, dermal contact, and inhalation pathway for occupation receptors. These concentrations of dioxins/furans occur at multiple locations associated with the former lumber mill operations located on tax lot 202 and 203 including the former green chain located in the center of the site, a wigwam burner area, and the former dip tank area. While the lateral extent of dioxins/furans in these areas has not been determined, it is reasonable to assume that these locations represent the worst-case concentrations of dioxins/furans at the site. Concentrations of benzo(a)pyrene in shallow soil samples (generally located between 1 to 2 feet bgs) exceeded the RBC protective of ingestion, dermal contact, and inhalation pathway for occupational receptors at a location associated with a former log pond on the northeast portion of the site. The lateral extent of benzo(a)pyrene in this area has only been partially delineated. Because a direct source area for these impacts is not evident, concentrations of this contaminant of concern (COC) are assumed to be potentially present within the footprint of a former log pond located in this area. The approximate boundary of the log pond is presented on Figure 2. Pentachlorophenol (PCP) was previously identified in groundwater associated with a former wood treatment dip tank located on the southeast corner of the site. Concentrations of PCP detected in the last four groundwater monitoring events conducted by GeoEngineers, Inc. at the site (between April 2010 and January 2013) indicated that the maximum concentrations of PCP in site monitoring wells MW-4B and MW-5 were below applicable RBCs. All site monitoring wells are anticipated to be decommissioned following regulatory site closure. 5.0 DESCRIPTION OF ROCK FILL LAYER As documented in previous investigations, the surface of most of the site is covered by pavement over a silty gravel fill or a thin layer of silt overlying silty crushed rock fill. It should be assumed that approximately 1 to 2 feet of crushed rock fill is present at locations across the site where the more recent lumber mill operations occurred, with the exception of soil 3 Project: No

5 Rock Fill Layer Management and Maintenance Plan directly underlying former building slab foundations (i.e., former green chain). Crushed rock fill was not encountered in these latter locations. A cross section depicting an interpretation of site geology based on boring and test pit logs is included as Figure 3. As part of the selected remedial alternative option (RAO) for the site, the Department of Environmental Quality (DEQ) agreed with the conclusion that this fill layer provides an adequate layer of protection for potential future exposure for occupational site workers through direct contact (ingestion or dermal contact) to soil contaminated with dioxin/furans and/or petroleum hydrocarbons. A condition of site closure is management and maintenance (as needed) of this layer. 6.0 MANAGEMENT OF ROCK FILL LAYER The rock fill layer at the site should consist of (at a minimum) at least one foot thickness of crushed rock or have an overlying impermeable surface material (e.g., paving or building foundation). During any future excavation activities, crushed rock removed as part of site improvement (e.g., grading, trenching) should be stockpiled separately and utilized for backfill in the same area, if possible. If backfill material is not needed, this material should stockpiled on the site for future use as fill material. Soil removed from below this layer should be managed in accordance with the site CMMP. During future site development activities, if areas are observed that are absent of a crushed rock fill layer or equivalent (e.g. pavement or building foundation), efforts will be undertaken to create a protective layer in these areas that consists of at least one foot of crushed rock or have an overlying impermeable surface (e.g. paved surface or building foundation. 7.0 MONITORING OF ROCK FILL LAYER The effectiveness of the rock cap relies on site inspections to ensure exposure to subsurface contaminated site soils is limited. Inspection, monitoring, and maintenance of the rock fill layer are the responsibility of the Property Owner. Annual inspections should be performed by the property owner to ensure that property tenants or other users are adhering to the management requirements of this plan. Any observed deficiencies should be corrected in a timely manner and should include follow-up inspection(s). At a minimum, the annual inspection should document any areas where the rock fill layer is determined to be absent or damaged, areas of ponding water, areas of soil erosion, and any areas where subsurface excavation has occurred (e.g. new buildings, utilities). 8.0 COMPLIANCE Site tenants and any contractors conducting excavation activities at the site should be provided with a copy of both this Plan and the site CMMP to assist in properly managing both the rock fill layer and any contaminated media encountered below this layer. As a condition of regulatory closure, both the Rock Fill Layer Management and Maintenance Plan and the CMMP will be recorded with the property deed by the property owner. Inspections, improvements and any other changes to the rock fill layer should be documented, including pictures and locations of improvements or changes on a site map. Documentation of these activities should be maintained with a copy of this plan at the site. 4 Project: No

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