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I t. . . -- EXECUTIVES~RY DPRA conducted this Phase II Investigation at the former Arden Hills Public Works Facility (Site) located at 1440 West Highway 96 in Arden Hills, Minnesota, between January 19, and February 11,2005. As part of the investigation, DPRA performed soil screening and sampling during the excavation of 21 test pits and advancement of II soil probes in accordance with DPRA's recommendations to the City of Arden Hills in its Phase I Environmental Assessment Report, dated December 16, 2004. Soil samples were collected from thesubsurface, and submitted to a laboratory for chemical analysis; the range of chemical analyses included: volatile organic compounds (VOCs), gasoline range organics (GRO), diesel range organics (ORO), polynuclear aromatic hydrocarbons (PAHs), RCRA metals, and polychlorinated biphenyls (PCBs). Specific analyses of each sample were based upon the potential contamination source in the area of the soil probes. Soil Conclusions The soil lithology identified with the sampling activities at the Site is consistent with the results from the test pits and the regional geologic information, which consist of up to 8 feet of mixed fill underlain by nati ve sandy clay till to a depth of at least 32 feet bgs. The fill appears to be a remnant of road construction projects and is composed of asphalt, concrete. gravel, crushed rock sand, and other materials such as wood mulch, chips, and tree trimmings, and street sweepings. In addition. a mixture a concrete, scrap metal, glass, electrical cords, metal cans, and wood was uncovered in a relatively isolated area southeast of the maintenance building. P AH constituents, metals, acetone and DRO were detected in the soil and fill materials throughout the Site. DPRA reported the presence of soil contamination to the State Duty Officer on February 18, 2005 in accordance with Minnesota Statute 115.061. The approximate extent of the soil contamination is indicated by the yellow dashed boundary line on Figure 2. To assess the extent and magnitude of the soil contamination, DPRA used the Minnesota Pollution Control Agency (MPCA) established soil reference values (SRVs) and the soil leaching values (SL Vs), which are presented in the MPCA Risk-Based Site Evaluation Guidance. dated November 2, 1999. No individual constituent concentration or benzo(a)pyrene (BaP) equivalent concentration exceeded the SRVs or SLVs in any of the samples collected. DRO concentrations ranged from <3.6 mg/kg to 92 mg/kg. There are no established SRV or SL V for DRO concentrations. GRO was not detected in any soil probe borings at concentrations greater than method detection limits. Although, the complete horizontal and vertical extent of the contaminated soil is undefined; however, the source of contamination appears to have been historical filling and application of used oil on the ground surface for dust suppression. Groundwater Conclusions No groundwater was encountered in any of the soil probe locations. According to other published reports, groundwater in the area of the Site is approximately 90 feet below the ground surface and flows to the southwest. The residual contamination in the on-site soil does not appear to pose a risk of impacting the groundwater at the Site. ~ Phase II Investigation Report .~H]US Former Public Works Facility ~~DPRA