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Phase I Environmental Site Assessment Old Snelling Avenue & County Road E Improvements WSB Project No. 015447-000 Page 1 1. Summary WSB was retained by the City of Arden Hills (City) to conduct a Phase I Environmental Site Assessment (ESA) for the proposed Old Snelling Avenue and County Road E Improvements project located in Arden Hills, Minnesota (the Project Corridor). The objective of the assessment was to identify Recognized Environmental Conditions (RECs) associated with the Project Corridor according to ASTM E1527-13 “Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessments”. The Project Corridor is a north-south segment of Old Snelling Avenue in Arden Hills, Ramsey County, Minnesota. The Project Corridor is approximately 0.8 miles long, extending from north of County Road E (approximately Arden Oaks Drive) at the north end to Trunk Highway (TH) 51 at the south end, including a proposed roundabout intersection at County Road E. The Project Corridor is in the western half of Section 34, Township 30N, Range 23W and in the southwest corner of Section 27, Township 30N, Range 23W. Land use surrounding the Project Corridor consists primarily of single-family dwellings with a commercial building at the north end. A Project Corridor Location map and a Project Corridor Details map are included as Figure 1 and Figure 2, respectively. WSB has performed this Phase I ESA in conformance with the scope and limitations of ASTM Practice E1527-13. Exceptions to or deletions from this practice are described in Section 2.3 of this assessment. This Phase I ESA has been prepared exclusively for the City. No additional parties may rely on the contents of this report unless written authorization is obtained from WSB. This Phase I ESA has identified two (2) RECs, no historical recognized environmental conditions (HRECs), and no controlled recognized environmental conditions (CRECs) in connection with the Project Corridor (see Figure 3). The following RECs were identified: REC-1: Contaminated Soils Encountered During Bridge Replacement Contaminated soil was encountered in 2018 during the replacement of Bridge 62J17 located on the southern portion of the Project Corridor. Soil samples collected from three stockpiles generated during construction identified benzo(a)pyrene (BaP) equivalent concentrations above the Minnesota Pollution Control Agency (MPCA) Screening Soil Leaching Value (SLV) and diesel range organics (DRO) above the MPCA’s criteria for unregulated fill. Based on the analytical results, a total of 486 cubic yards of polycyclic aromatic hydrocarbon (PAH)- and DRO-impacted soil was removed during bridge construction and disposed offsite at a certified landfill. It is possible that contaminated soil remains in this area. The former and/or current presence of PAH- and DRO- impacted soil in the vicinity of Bridge 62J17 is considered a REC. REC-2: Petroleum Odor Noted During Geotechnical Investigation At total of 15 geotechnical soil borings were advanced along the Project Corridor in 2019 in preparation for roadway improvements. The borings were advanced to 14.5 feet below grade and approximately every 400 linear feet along the Project Corridor. While completing the borings, an “apparent hydrocarbon odor” was noted in 11 of the 15 boring locations at depths ranging from 0.3 to 14.5 feet below grade. No analytical soil samples were collected during the geotechnical investigation. The presence of petroleum odors noted throughout the Project Corridor during the 2019 Geotechnical Investigation is considered a REC. Additionally, the following items of environmental note were identified: Spill Listings Multiple Spills and Historical Spills incidents were listed at the Project Corridor and/or at sites located adjacent to the Project Corridor. The reported spills were surficial in nature and did not impact soil or groundwater. All reported Spills / Historical Spills listings have been issued closure by the MPCA. It is possible that documented and/or undocumented spills may be encountered during roadway improvements.