Limited Site Investigation Report Twin Cities Army Ammunition Plant 585 Acre Transfer Property Leak Number Arden Hills, Minnesota

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1 Environment Prepared for: Prepared by: MN Pollution Control Agency AECOM St. Paul, Minnesota Minneapolis, MN Project November 2011 Limited Site Investigation Report Twin Cities Army Ammunition Plant 585 Acre Transfer Property Leak Number Arden Hills, Minnesota

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3 Investigation Report Form Guidance Document 4-06 Complete this form to document site investigation activities, including Limited Site Investigations (LSIs) and Remedial Investigations (RIs). Do not revise or delete any text or questions from this report form. Include any additional information that is important for making a site management decision. If only an LSI is necessary, some questions do not need to be answered and have been identified in the form. Highlighted text contains instructions and references to related guidance documents for that section or question. Refer to Minnesota Pollution Control Agency (MPCA) Guidance Document 1-01 Petroleum Remediation Program General Policy for the overall site investigation objectives and to other MPCA guidance documents for details on investigation requirements and methods. MPCA Site ID: Leak Date: November 11, 2011 Responsible Party Information Name: United States (U.S.) Army Phone #: (651) Responsible Party Contact: Mr. Mike Fix, Commanders Representative Mailing Address: 470 Highway 96, Suite 100 City: Shoreview Zip Code: The MPCA is Conducting Site Responses for Leak under the Fund Financed Petroleum Remediation Program (PRP). MPCA Contact: Mr. Mark Koplitz Phone #: (651) Leak Site Information Leak Site Name: Twin Cities Army Ammunition Plant (TCAAP) Phone #: (651) Leak Site Address: 4700 Highway 10 City: Arden Hills Zip Code: County: Ramsey Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program F Minnesota Pollution Control Agency

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5 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 3 Emergency and High Priority Sites A. Is an existing drinking water well impacted or likely to be impacted within a two-year travel time? B. Is a hydrogeologically sensitive aquifer impacted that is tapped by water wells that are within 500 feet from the release source? If YES, explain below. C. Has the public water supply risk assessment concluded that the site is a high priority site with respect to a public water supply well (see Guidance Document 4-18 Public Water Supply Risk Assessment at Petroleum Remediation Sites)? Yes Yes Yes No No No The Site is located within the New Brighton Drinking Water Supply Management Area (DWSMA). The City of New Brighton obtains its municipal water supply from ten (10) supply wells set in the Prairie du Chien/Jordan and Mount Simon/Hinckley aquifers. The Minnesota Department of Health (MDH) Source Water Assessment (SWA) indicates that the aquifer sensitivity is low to medium for the City of New Brighton municipal supply wells as these wells meet the well construction standards and do not present a pathway for contamination to readily enter the water supply. Groundwater contamination consisting of chlorinated solvent compounds associated with the TCAAP Site was detected in the Prairie du Chien/Jordan resource aquifer and in City of New Brighton municipal supply wells. New Brighton municipal water obtained from wells set in the Prairie du Chien/Jordan aquifer where chlorinated contamination exists is treated to remove chemical solvent contamination and naturally occurring iron and manganese prior to distribution. The Site is located outside the City of Mounds View s DWSMA. The City of Arden Hills purchases treated water for municipal supply from the Saint Paul Regional Water Services. Information obtained for the public water supply risk assessment is included in Appendix L. D. Is there an existing surface water impact as indicated by 1) a petroleum sheen on the surface water or 2) a petroleum sheen or volatile organic compounds in the part per million range observed in a ground water sample collected close to the surface water? E. Has free product been detected at the site? If YES, attach Guidance Document 2-03 Free Product Recovery Report Worksheet in Section 6. F. Are there any existing field-detectable vapor impacts (photoionization detector, explosimeter, odors, etc.) to a receptor? Yes Yes Yes No No No G. Did the vapor intrusion assessment detect contaminants in excess of acute intrusion screening values (see Guidance Document 4-01a Vapor Intrusion Assessments Performed during Site Investigations)? Yes No NA Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

6 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 4 A vapor intrusion assessment was not requested by the MPCA for Leak as part of this Limited Site Investigation (LSI) scope of work. No inhabited receptors were located within 500 feet of the release area(s) at the time of the LSI work. If you answered YES to any of questions A through G above, describe below the actions taken to date to reduce or eliminate the risk posed by the release. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

7 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 5 Section 1: Site Assessment Site and Release Information Complete Guidance Document 1-03a Spatial Data Reporting Form, Guidance Document 2-05 Release Information Worksheet if 3-02 General Excavation Report Worksheet was not completed, and include in Section Describe the land use and pertinent geographic features (e.g., topographic changes, surface waters, etc.) within 1,000 feet of the site. Illustrate these features using the Site Location Map, aerial photographs, and Sanborn Fire Insurance Maps for the various time periods they are available in Section 4. The project site (Site) consists of approximately 585 acres of land along the western portion of the larger Twin Cities Army Ammunition Plant (TCAAP) facility located in the City of Arden Hills, Ramsey County, Minnesota. The approximate Site location boundary is illustrated on the attached Figure 1. An aerial photograph depicting the Site area is included as Figure 2. The Site was identified as the 585-acre transfer property by the current property owner, the United States Government, and this term is used to reference the investigation Site throughout this document. The Site at the time of the LSI activities completed by AECOM in December 2010 through May 2011 contained vacant manufacturing and support buildings, roadways and parking lot areas. Remediation system structures and components associated with ongoing remedial activities were also present at the Site. A mix of residential and commercial properties is located west of the Site across Highway 35/Highway 10 and south of the Site across Highway 96. State of Minnesota properties including the Minnesota Department of Transportation (MnDOT) Arden Hills truck station, a Department of Motor Vehicles (DMV) license and road test facility, Minnesota State Patrol Training Center and Minnesota Department of Fleet and Admin Surplus Services are located directly north of the Site. Residential properties are located approximately 1,000 feet north of the Site across County Road I. The adjacent property directly east of the Site consists of the Arden Hills Army Training Site (AHATS). Rice Creek flows through the northwestern portion of the Site and a small unnamed surface water feature is located along the northern portion of the Site. Round Lake is located approximately 1,000 feet to the south. The topographic land surface elevation varies from a low of approximately 880 feet above mean sea level in the northern portion of the Site to a high of approximately 1000 feet above mean sea level in the southeastern portion of the Site. The Site was previously divided into smaller sections for the Plexus Scientific (Plexus) Phase I/II Environmental Site Assessment (ESA) Report in order to facilitate the review of historical documentation and to reduce the Site reconnaissance and field activities into manageable sections. AECOM is utilizing the previously established system of section designation by Plexus for this LSI report for consistency and referencing between Site areas. A Site Diagram illustrating the section designations is included as Figure 3. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

8 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page Briefly describe the history of the site and any past site investigation work that may have been completed. If a Phase I or Phase II report has been prepared for this site, include a copy in Section 6. Brief Site History The following brief Site history is based on information provided in the Plexus Phase I/II ESA Report, dated February 24, The 585-acre transfer property (Site) was included in a land purchase by the United States (U.S.) Army in The entire TCAAP Site occupied approximately 2,370 acres. A Site Location Diagram illustrating the 585-acre transfer property is included as Figure 1 and an aerial photograph of the Site is included as Figure 2. The Site property was previously owned by private landowners with the main Site uses including residential, farming and agricultural. One former gas station (former Phillips 66 Station) was identified in the southwest portion of the Site. The former location of the gas station is likely under the current Interstate 35W/Highway 10 ramp. A former Oil Filling Station was located in the southwest portion of Section 3008 in 1941 according to the Plexus Phase I/II ESA. The Site was operated under the Government-Owned Contractor-Operated (GOCO) war materials production program established by the War Department during World War II. Construction of the plant was initiated in August 1941 and small arms ammunition production began in February The plant was temporarily idle after the Victory over Japan Day (September 2, 1945). The plant was put back in service by the U.S. Army in 1946 for the Korean conflict and remained in operation until The plant was re-opened in 1965 during the Vietnam War for manufacturing small arms ammunition and was returned to standby status in Federal Cartridge Company was the prime operating contractor at the Site from 1941 into the 1990 s. The Site was placed on modified caretaker status in Portions of the Site were leased to private companies for various uses including ATK (formerly Honeywell, Inc.) Numerous petroleum products were utilized at the Site during plant operation including: heating oil (diesel and No. 6 fuel oil), vehicle fuels (No. 1 diesel, leaded and unleaded gasoline), quench oil, waste oil and hydraulic oil. Descriptions of the small arms production processes conducted at the Site are included in the Plexus Phase I/II ESA. Past Site Investigation Work Numerous Site investigations have been completed at the Site associated with multiple possible contaminant sources including: petroleum compounds, chlorinated compounds, metals, polychlorinated biphenyls (PCBs), energetic material (explosives, propellants, tracer and igniter compounds), radiological materials and herbicides. The focus of this LSI is on petroleum related contamination; therefore, the following summary of past Site investigation work is generally limited to past petroleum related Site investigations. Significant additional Site investigation and remediation work was completed at the Site to determine the extent and magnitude of non-petroleum related contamination. Three historic petroleum release sites (Leak Numbers 3635, 4852 and 6996) were identified and investigated within the 585-acre transfer property Site. The historic petroleum release site locations are illustrated on Figure 2. A summary of the historic petroleum leak site locations by Leak number is provided in the paragraphs below. The MPCA Petroleum Remediation Program (PRP) established Leak number as a new Leak number to encompass the entire 585-acre transfer property Site and to investigate the Site as a whole. Leak encompasses potential petroleum release source Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

9 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 7 areas where no investigation work has been completed or where additional investigation was required based on existing Site data including the former release Sites. The Site was also entered into the Petroleum Brownfield Program (PBP) under Site number 3668 associated with potential Site redevelopment. Leak number 3635 is located within Section 2003 near Building 59 where a 715 gallon heating oil aboveground storage tank (AST) was removed in MPCA closed Leak 3635 on February 10, 1992 based on soil samples and soil borings completed to determine the extent of petroleum impacts. Leak number 4852 is located within Section 1012 and portions of Section 1009 in an area where numerous underground storage tanks (USTs) and ASTs were formerly located in a tank farm area. MPCA closed Leak 4852 on December 18, 1996 based on Site investigation activities completed in this area. Leak number 6996 is located within Section 1010 where numerous USTs and ASTs were formerly located in a tank farm area. The MPCA closed Leak 6996 on May 31, 1996 based on Site investigation activities completed in this area. Eleven petroleum Leak sites were identified within the original TCAAP property boundary but outside of the 585-acre transfer property including Leak numbers 2593, 2803, 3188, 3609, 5753, 13336, 13461, 13886, 14688, and The locations of these leak sites are illustrated on Figure 2. Leak numbers 2593, and are associated with the MnDOT Arden Hills Truck Station located north of the Site. Leak 2803 is associated with the MnDOT Training Facility located north of the Site and Leak 13461is associated with the State of Minnesota Administration Surplus Services facility located north of the Site. Leak 3188 is located on the far southeastern portion of the TCAAP property at Highway 96 and Lexington Avenue at the Army Reserve facility. Leaks 3609 and 5753 are located at the National Guard Combined Organization Maintenance facility on Highway 96 and Hamline Avenue east of the Site. Leak is located directly east of the 585-acre transfer property and is likely associated with former ASTs in the vicinity of Building 515. Leak is associated with the Arden Hills Waste Oil Disposal site east of the Site. Leak is located at the Ramsey County Public Works facility on 1425 Paul Kirkwold Drive east of the Site. Leak is identified as a TCAAP leak site; however, the physical location of the release is identified as off the TCAAP property. The site address listed for Leak is 5th Street NW in New Brighton which is adjacent to the public works facility at 700 5th Street NW. This site is the location of the Plume Groundwater Recovery System (PGRS) installed in 1993 for the City of New Brighton. Leak was associated with soil contamination encountered during installation of the plume groundwater recovery well, Municipal Well Number 13 (unique #520931) for the PGRS. The well log for Municipal Well Number 13 is included in Appendix K. Other pertinent site assessment/investigation reports associated with the TCAAP property include: Environmental Site Assessment Phase I and Phase II Report Final, Twin Cities Army Ammunition Plant, Arden Hills, Ramsey County, Minnesota 774-Acre Parcel. By: Plexus, dated February 20, The Phase I/II ESA included site investigation at seventeen former UST and AST locations as well as former production areas not directly associated with storage tanks. A copy of the Phase I/II ESA is on file at the MPCA. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

10 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 8 Addendum Report for Phase I and Phase II Environmental Site Assessment, TCAAP. By: TWISS, dated February Supplemental Remedial Investigation (RI), Field Sampling Plan, TCAAP 585-Acre Transfer Property. By: Tetra Tech, dated September Fiscal Year 2009 Annual Performance Report, New Brighton/Arden Hills Superfund Site, by Wenck Associates, Inc., dated May List other potential petroleum sources within 500 feet of the site and identify them on the Potential Receptor Map in Section 4. Other petroleum release sites identified within the original TCAAP property boundary are discussed in Section 1.2 above and their locations are illustrated on Figure 2. No other potential petroleum sources were identified within 500 feet of the release sites. 1.4 Describe the status of the tank system(s) including current and former tanks, piping, and dispensers. Summarize the status and characteristics of all past and present tanks in Table 1 and identify all components on a Site Map. A total of sixty-three (63) former petroleum storage tanks were identified within the 585 acre transfer property. A summary of the petroleum storage tank information is included on Table 1. The locations of the former tanks are illustrated on Figure 9. Tank information was obtained from the Plexus Phase I/II ESA as well as the MPCA tanks database. AECOM also interviewed Mr. Mike Fix (U.S. Army) regarding the status of tanks at the Site. Mr. Fix indicated that to the best of his knowledge, all petroleum storage tanks were removed from the Site. He was not aware of any remaining petroleum storage tanks at the Site. Documentation information including removal dates was not identified for eleven (11) ASTs including tank numbers: 3, 4, 5, 6, 17, 18, 37, 42, 55, 56 and 75. ASTs with a capacity of 500 gallons or less are exempt from MPCA AST regulations. Nine (9) of the 11 AST tanks including Tanks 3, 4, 5, 6, 17, 18, 37, 55 and 56 had a capacity of 500 gallons or less and were therefore likely not registered storage tanks. Tank 42 was a 20,000 gallon cutting oil AST that was installed in 1941 and may have been removed prior to implementation of the current AST regulations regarding tank documentation. Tank 75 was reportedly a 550 gallon gasoline AST installed in 1985 approximately 45 feet northwest of Building 502 in Section Soil boring SI-4008-B1 was completed in the immediate vicinity of the former Tank 75 location and no evidence of the AST was identified. AECOM did not observe the presence of petroleum ASTs during the Site investigation work. Tank numbers 17 and 18 were reportedly located within structures (Buildings 115 and 117A, respectively). AECOM did not observe the inside of existing structures for the presence of tanks or tank systems. 1.5 Briefly describe the known or suspected source(s) of the release and how it was discovered. The suspected sources of the releases are historic spills and/or releases from numerous petroleum storage tank systems (USTs and ASTs) located throughout the Site and the general Site use as an industrial facility for the manufacturing of small arms ammunition. 1.6 When did the release occur (if known)? Unknown 1.7 What was the volume and type(s) of petroleum product released (if known)? Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

11 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 9 Unknown gallons Released product type(s): Unknown When a tank has been excavated, refer to Guidance Documents 3-01 Excavation of Petroleum Contaminated Soil and Tank Removal Sampling and 3-02 General Excavation Report Worksheet for reporting requirements. If a tank has been excavated or if contaminated soil was removed for offsite treatment prior to this investigation, include Guidance Document 3-02 in Section Was soil excavated for off-site treatment? Yes No* *Soil excavation was not conducted as part of the Site investigation work completed by AECOM. Petroleum contaminated soil was removed at multiple locations during various historic tank removals as noted on Table 5-2 from the Plexus Phase I/II ESA. Historic soil removal information is included on Table 1 under the Location and Description column. Date(s) soil was excavated: Total volume removed: cubic yards Volume of total soil removed that was petroleum saturated: cubic yards Soil treatment method: Land treatment Thermal treatment Composting/Biopiling Other ( ) Name and location of treatment facility: If you checked Other, describe how the soil was treated and attach applicable documentation at the end of the reporting form. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

12 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 10 Site-Specific Geology and Hydrogeology 1.9 Discuss the soil borings drilled and provide rationale for their locations. Include boring logs in Section 6. Boring logs must include all the information required in Guidance Document 4-01 Soil and Ground Water Assessments Performed during Site Investigations. AECOM completed a total of sixty-seven (67) soil borings and fifty-seven (57) surface soil assessment borings to further determine the extent and magnitude of petroleum contamination at the Site. The soil boring locations are illustrated on Figures 3 through 8. Soil boring logs are included in Appendix E. Soil boring locations were selected based on areas where historic petroleum storage tanks were identified but not previously investigated or where additional investigation was required based on evidence of petroleum contamination including the presence of DRO soil concentrations above 50 mg/kg identified in previous Site assessments/investigations including the Plexus Phase I/II ESA and Tetra Tech Supplemental RI. Other portions of the Site investigated by AECOM include non-tank areas where evidence of petroleum impacts was identified during previous Site assessments/investigations completed by others. Groundwater analytical sampling was completed in Sections 2003 and 1017 by installing temporary wells in soil borings. Section 2003 consisted of the former housing area where numerous fuel oil ASTs and a fuel oil UST (Tank 59) were located. A petroleum release (Leak 3635) associated with Tank 59 was previously investigated and was closed by the MPCA. Three petroleum ASTs (Tanks 3, 4 and 5) were located in Section Groundwater sampling was conducted around Tank 5 after evidence of petroleum contamination was identified in the soil boring completed in the vicinity of this former tank location. Following is a summary of soil borings and surface soil assessment borings completed by AECOM for the LSI by Section. Section 1001 (Building 101 Figure 6) Five soil borings (SI-1001-B28 through SI-1001-B32) were completed in Section 1001 to further define the extent of soil contamination previously identified beneath the slab in the northeast portion of Building 101 during the Plexus Phase I/II ESA. Section 1002 (Building 108 Figure 6) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1003 (Building 102 Figure 6) One soil boring (SI-1003-B34) and two surface soil assessment borings (SI-1003-SS39 and SI SS40) were completed on the east side of Building 102 to further define diesel range organic (DRO) soil contamination previously identified in a surface soil sample (SS ) collected during the Plexus Phase I/II ESA at this location. Section 1004 (Building 151 Figure 6) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1005 (Former Building 504 Figure 6) One soil boring (SI-1005-B22) was completed in the immediate vicinity of former Tank 22 (265 gallon diesel AST) to determine the potential of a petroleum release associated with this AST. No historic Site investigation work associated with tank 22 was identified. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

13 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 11 Section 1006 (Figure 7) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1007 (Figures 6 and 7) Two soil borings (SI-1007-B20 and SI-1007-B33) and four surface soil assessment borings (SI SS31 through SI-1007-SS34) were completed in Section Soil boring SI-1007-B20 and surface soil assessment borings SI-1007-SS31 through SI-1007-SS34 were conducted in the immediate vicinity of Tank 21 to determine the extent of impacts around the former diesel AST. The surface soil assessment borings were completed based on the presence of DRO soil contamination identified in a surface soil sample (RI ) collected during the 2007 Tetra Tech Remedial Investigation (RI). Soil boring SI B33 was completed in the immediate vicinity of Tanks 19 and 20 (265 gallon diesel ASTs) to determine the potential of a petroleum release from these tanks. Section 1008 (Building 111 Figure 6) Five soil borings (SI-1008-B23 through SI-1008-B27) were completed in Section 1008 to further determine the extent of DRO contamination identified in soil boring RI conducted near an underground sewer line during the 2007 Tetra Tech RI. DRO contamination was detected in the Tetra Tech soil boring at depths of one foot and eight feet below grade. Section 1009 (Building 115 Figure 6) Two soil borings (SI-1012-B38 and SI-1012-B39) were completed in Section 1009 but were associated with the former fuel farm area in Section See Section 1012 for more detail on these borings. The Plexus Phase I/II ESA did not identify significant petroleum contamination associated with three former ASTs (Tanks 6, 17 and 83) located in Section Section 1010 (Buildings 112 and 114 Figure 4) Ten former USTs (Tanks 7, 8, 9, 10, 12, 13, 14, 15, 16 and 81) and one AST (Tank 11) were located in Section These tanks were associated with a tank farm area which was investigated under MPCA Leak #6996. Leak #6996 was closed by the MPCA on May 31, An RI soil boring (RI ) completed by Tetra Tech in 2007 indicated the presence of DRO contaminated soil south of Building 114. Five soil borings (SI-1010-B43 through SI-1010-B47) were completed by AECOM to further determine the extent of petroleum contamination in Section Section 1011 (Building 105 Figure 7) No former USTs or ASTs were identified in Section 1011 and no significant evidence of a petroleum release was identified in this Section based on the Plexus Phase I/II ESA. A surface soil sample (RI ) conducted by Tetra Tech in 2007 indicated the presence of DRO contamination northwest of Building 105. AECOM completed one soil boring (SI-1011-B21) to determine the vertical extent of petroleum contamination in the vicinity of RI AECOM also completed four surface soil assessment borings (SI-1011-SS35 through SI-1011-SS38) to determine the horizontal extent of surface soil contamination. Section 1012 (Former Fuel Farm Figure 6) Five former USTs (Tanks 25, 26, 27, 28 and 29) and four former ASTs (Tanks 30, 31, 32 and 44) were located in Section These tanks were associated with a tank farm area which was investigated under MPCA Leak #4852. Leak #4852 was closed by the MPCA on December 18, Additional Site work completed by Tetra Tech in 2007 indicated the presence of DRO contaminated soil east of Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

14 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 12 Building 158 (former oil pump house) and near former Tank 25. AECOM completed five soil borings (SI-1012-B35 through SI-1012-B39) to further determine the extent of soil contamination in the former tank farm area. Section 1013 (Building 103 and IRP Site K Figure 4) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1014 (Building 157 Figure 6) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1015 (Building 104 Figure 6) No former USTs or ASTs were identified in this section and no significant evidence of a petroleum release was identified based on the Plexus Phase I/II ESA results. Surface soil sampling conducted by Tetra Tech in 2007 (RI ) indicated DRO contamination near the northwest corner of Building 104. AECOM completed one soil boring (SI-1015-B40) and four surface soil assessment borings (SI SS40 through SI-1015-SS43) to further determine the extent of DRO contamination. Section 1016 (Figures 4 and 6) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 1017 (Figure 4) Three former ASTs including Tanks 3, 4 and 5 were located in the southern portion of Section Tanks 3 and 4 consisted of 500 gallon gasoline ASTs and Tank 5 consisted of a 300 gallon number 1 diesel fuel AST. No Phase II ESA activities associated with the former ASTs were completed by Plexus in Section AECOM completed six soil borings (SI-1017-B48, SI-1017-B49, SI-1017-B50, SI-1017-B65, SI B66 and SI-1017-B67) to determine the extent of contamination associated with the former ASTs. Groundwater samples were collected from temporary monitoring wells completed in the soil borings (SI-1017-B48A, SI-1017-B65 through SI-1017-B67) around Tank 5 based on the presence of petroleum contaminated soils encountered in SI-1017-B48 at the shallow water table interface of one to two feet below ground surface. Section 2001 (Building 189 Figure 4) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 2002 (Rice Creek Figure 4) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 2003 (Former Housing Area Figure 4) Fourteen former ASTs (Tanks 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70 and 71) and one UST (Tank 59) were located in Section ASTs 57, 58 and 60 through 71 consisted of 265 gallon heating Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

15 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 13 oil ASTs which were located in the basements of the residential houses. Tank 59 consisted of a 715 gallon heating oil UST. Tank 59 was investigated under Leak number 3635 and the Site was closed by the MPCA on February 10, AECOM completed seven soil borings (SI-2003-B58 through SI-2003-B64) to determine the potential for a release associated with the former heating oil ASTs and collected groundwater samples from temporary monitoring wells completed in soil borings SI-2003-B58, SI-2003-B61 and SI-2003-B64. Section 3001 (Building 190 Figure 5) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 3002 (Building 717 Figures 5 and 6) No former USTs or ASTs were identified in this Section. A surface soil sample (SS ) collected during the Plexus Phase I/II ESA indicated the presence of DRO contamination. AECOM completed one soil boring (SI-3002-B42) and four surface soil assessment borings (SI SS52 through SI-3002-SS55) to determine the extent of petroleum contamination. Sections 3003 to 3006 (135 PTA Area Figure 5) No former USTs or ASTs were identified in these Sections. No soil borings were completed in these Sections for the LSI. Section 3007 (Figure 5) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 3008 (IRP Site C Figure 5) An Oil Filling Station was located in the southwest portion of Section 3008 in 1941 according to the Plexus Phase I/II ESA report. No information regarding USTs or ASTs was identified associated with the former Oil Filling Station. The results of a temporary well/soil boring (SS/SB/GW ) conducted by Plexus indicated DRO present in the groundwater at this location. The Plexus boring also indicated shallow groundwater at approximately 5 feet at this location. Soil boring RI conducted by Tetra Tech in 2007 in the general vicinity of the former Oil Filling Station indicated DRO soil contamination at a depth of 5 feet to 6 feet. AECOM completed five soil borings (SI B51 through SI-3008-B55) to determine the extent of contamination near the former Oil Filling Station. DRO contamination was detected in two Tetra Tech surface soil samples (RI and RI ) and a subsurface soil sample (RI (5-6 )) northeast of the former Oil Filling Station area. AECOM completed one soil boring (SI-3008-B56) and four surface soil assessment borings (SI SS44 through SI-3008-SS47) in the vicinity of RI to further determine the extent of petroleum contamination at this location. AECOM also completed one soil boring (SI-3008-B57) and four surface soil assessment borings (SI-3008-SS48 through SI-3008-SS51) in the vicinity of RI to further determine the extent of petroleum contamination at this location. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

16 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 14 Section 4001 (Building 116 Figure 6) Two former ASTs (Tanks 18 and 33) were located in the northeast portion of Section Tank 18 consisted of a 265 gallon, number 1 diesel fuel AST. Tank 33 consisted of a 265 gallon home heating oil AST. A surface soil sample and soil boring (SS/SB ) was completed during the Plexus Phase I/II ESA in the vicinity of Tank 33. No significant evidence of petroleum contamination was identified near Tank 33 based on the Plexus investigation. AECOM completed one soil boring (SI-4001-B41) in the immediate vicinity of Tank 18 to determine the potential of a petroleum release at this location. Section 4002 (Figure 6) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 4003 (Figure 7) No former USTs or ASTs were identified in this Section. No soil borings were completed in this Section for the LSI. Section 4004 (Building 594 Figure 7) No former USTs or ASTs were identified in Section Building 594 was completed in 1942 as a machine maintenance building. DRO contamination was detected in surface soil sample SS collected during the Plexus Phase I/II ESA. AECOM completed one soil boring (SI-4004-B19) and three surface soil assessment borings (SI SS28 through SI-4004-SS30) to further determine the extent of petroleum contamination. Section 4005 (Building 503 Figure 7) No former USTs or ASTs were identified in Section DRO was detected in three surface soil samples collected by Plexus including SS , SS and SS AECOM completed three soil borings (SI-4005-B16 through SI-4005-B18) and nine surface soil assessment borings (SI-4005-SS19 through SI-4005-SS27) to further define the extent of petroleum contamination in Section Section 4006 (Former Buildings 557 and 587 Figure 7) One former tank (Tank 51) consisting of a 2,170 gallon gasoline/diesel fuel number 2 UST was located in Section Plexus completed a soil boring (SS/SB ) at this location to a depth of 25 feet. DRO contamination was detected in the soil sample collected from this boring at a depth of 3 feet to 5 feet. A soil sample collected from this boring at a depth of 8 feet to 10 feet was non-detect for DRO indicating the vertical extent of DRO contamination was defined. AECOM completed three soil borings (SI-4006-B13 through SI-4006-B15) to further determine the extent of petroleum contamination. Section 4007 (Former Building 501 Figure 8) Two former USTs (Tanks 38 and 39) and two former ASTs (Tanks 35 and 36) were located in Section Tank 38 consisted of a 2,750 gallon waste oil UST and Tank 39 consisted of a 2,100 gallon heating oil UST. Tanks 35 and 36 consisted of 27,200 gallon quench oil ASTs. Plexus completed soil boring SB in the location of former Tanks 35 and 36 and no evidence of a petroleum release Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

17 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 15 was identified at this location. Plexus completed soil boring SB in the location of former Tank 38 and no evidence of petroleum contamination was identified at this location. Plexus completed soil boring SB in the location of former Tank 39 and no evidence of a petroleum release was identified at this location. DRO contamination was detected in four surface soil samples collected during the Plexus Phase I/II ESA including SS , SS , SS and SS AECOM completed four soil borings (SI-4007-B8, SI-4007-B9, SI-4007-B10 and SI-4007-B12) and nine surface soil assessment borings (SI-4007-SS10 through SI-4007-SS18) were completed to further determine the extent of petroleum contamination in Section Section 4008 (Building 502 and IRP Site I Figure 8) One former UST (Tank 40) and six former petroleum ASTs (Tanks 41, 42, 55, 56, 75 and 82) were located in Section Tank 40 consisted of a 2,180 gallon gasoline UST. Tank 41 consisted of a 265 gallon number 1 diesel fuel AST, Tank 42 consisted of a 20,000 gallon cutting oil AST, Tanks 55 and 56 consisted of 300 gallon gasoline ASTs, Tank 75 consisted of a 550 gallon gasoline AST and Tank 82 consisted of a 2,000 gallon hydraulic oil AST. Plexus completed one soil boring (SB ) in the vicinity of Tanks 40, 41 and 75 to a depth of 20 feet. No evidence of petroleum contamination was identified by Plexus in the soil boring conducted based on field evidence and no laboratory analytical samples for soil or groundwater were collected from this boring. Seven soil borings (SI-4008-B1 through SI-4008-B7) and eleven surface soil assessment borings (SI-4008-SS1 through SI-4008-SS9, SI-4008-SS4A and SI-4008-SS5A) were completed by AECOM to further determine the extent of petroleum contamination in Section 4008 associated with the UST and ASTs and possible petroleum soil contamination (DRO) detected in surface soil samples collected by Tetra Tech in Section 4009 (IRP Site J Figure 8) One former AST (Tank 37) was located in Section Tank 37 consisted of a 265 gallon heating oil AST. No Phase II investigation sampling was conducted by Plexus in the vicinity of Tank #37. One soil boring (SI-4007-B11) was completed by AECOM in the immediate vicinity of Tank 37 to determine the potential for a release associated with the former AST Indicate the locations and depths of soil samples submitted for grain size analysis. Grain size analysis samples were not requested by the MPCA under this scope of work. The Site hydrogeology was determined based on historic Site assessment/investigation work completed at the Site Discuss in detail the site geology based on soil boring data, grain size analyses, cross sections, geologic logs of nearby water wells, and available published information. Include detailed descriptions of more porous lenses or stringers within tighter soil types. Quaternary soils at the Site consist primarily of glacial drift associated with the Superior Lobe and Grantsburg Sublobe glaciations. The unconsolidated glacial deposits in the vicinity of the Site are subdivided into four major formations including: the Hillside Sand, overlain by either the Arsenal Sand or Twin Cities Formation, followed by Lacustrine Deposits (Plexus Phase I/II ESA, 2004). The Hillside Sand consists primarily of poorly sorted, medium to coarse-grained sand associated with a proglacial outwash deposit based on the Surficial Geology of the New Brighton Quadrangle, Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

18 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 16 Minnesota by John E. Stone, dated 1966 (Stone, 1966). The Arsenal Sand is comprised of gray to brown, well sorted, fine to coarse-grained sand. These two sand units range in thickness from approximately 40 feet to 320 feet (Plexus Phase I/II ESA, 2004). The Twin Cities Formation consists of a mixture of light gray to very pale brown till and reddish-brown till and ranges in thickness from approximately 30 feet to 110 feet. The overlying Lacustrine Deposits consist of varying amounts of sand, silty sand and clayey silt sediments deposited by the marginal lakes of the retreating Grantsburg Sublobe and range in thickness from approximately 0 to 60 feet (Stone, 1966). Depth to bedrock in the area ranges from approximately 150 feet to approximately 400 feet (Depth to Bedrock Map, Mossler & Cleland, 1992). The bedrock units encountered at the Site include the Prairie du Chien Group overlying the Jordan Sandstone Formation followed by the St. Lawrence and Franconia Formations. The Prairie du Chien is present beneath the majority of the Site; however, narrow and steep-sloped bedrock valleys are present on the northern portion of the Site and just east of the Site where the Prairie du Chien is absent and the Jordan Sandstone and St. Lawrence/ Franconia Formations are the first encountered bedrock units. Soils observed in the borings completed by AECOM generally ranged from fine to coarse sand and silty sand associated with Lacustrine Deposits over sandy, silty clay likely associated with the Twin Cities Formation. Soils observed in the northern and central portions of the Site consisted predominantly of shallow fine sand and silty sand over clay. The southern portion of the Site consisted predominantly of fine to coarse sand to depths of up to approximately 50.5 feet (soil boring SI B1) with local areas of sandy, silty clay. Soils encountered in the northwestern portion of the Site (Section 2003) consisted of fine sand with silt lenses to approximately 30 feet. Fill soils including fine to medium sand, sandy clay and silty sand were encountered in numerous soil borings across the Site. The fill soils were generally encountered within the upper ten feet of the soil borings. A cross-section alignment and cross-section diagrams illustrating the stratigraphy observed in the soil borings completed for the LSI are included in Figures 10A through 10D Discuss in detail the local and regional hydrogeology based on geologic logs of nearby water wells and available published information. Previous investigations at the Site have categorized the Quaternary deposits and bedrock units into four hydrologic units. Unit 1 consists of all the Lacustrine deposits above the Twin Cities Formation. Groundwater in Unit 1 is generally perched and discontinuous, and exhibits seasonal fluctuations (Plexus Phase I/II ESA, 2004). Unit 2 includes the Twin Cities Formation and is generally comprised of a clay aquitard with interbedded sand and gravel lenses that may contain water. Unit 3 is comprised of the Hillside and Arsenal sands located beneath the Twin Cities Formation and above the bedrock. Unit 4 consists of the Prairie du Chien Group and Jordan Sandstone bedrock units. The most widely utilized hydrogeologic units in the area for water supply consist of the Prairie du Chien/Jordan aquifer followed by the Mt. Simon/Hinckley aquifer. The Prairie du Chien aquifer beneath the Site and immediately down-gradient of the Site is contaminated with chlorinated volatile organic compounds (cvocs). The City of New Brighton has municipal supply wells installed in the Prairie du Chien/Jordan Sandstone; however, the water is treated at their large permanent granular activated carbon water treatment facility (PGACWTF) prior to distribution to remove contaminants of concern (COCs). The treatment system also acts as groundwater remediation for the contaminated bedrock aquifer and reduces the migration of COCs in the down-gradient direction. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

19 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 17 The hydrogeologic units encountered in the soil borings conducted for this LSI consisted of Unit 1 (Lacustrine Deposits) and Unit 2 (Twin Cities Formation). Groundwater was generally not encountered in soil borings conducted in the southeastern portion of the Site (Sections 4005 through 4009). The deepest soil boring completed in this area was SI-4008-B1 to a depth of 50.5 feet and no evidence of groundwater was encountered at this location. Groundwater as shallow as one foot below grade was encountered in the north-central portion of the Site in Sections 1017 and The average depth to groundwater in the northwestern portion of the Site (Section 2003) was approximately 16 feet below grade Discuss site ground water flow direction using soil boring data, monitoring well data if collected, plume geometry, and available published information. Groundwater flow in Unit 1 (Lacustrine deposits) is generally to the west towards Rice Creek in the northern portion of the Site and to the southwest in the southern portion of the Site. Limited groundwater flow occurs in Unit 2 (Twin Cities Formation) as this unit is generally an aquitard; however, groundwater migration is likely vertical through the unit or horizontal along sand and gravel lenses. In Units 3 (Hillside and Arsenal Sands) and 4 (Bedrock Aquifers), groundwater flow is predominantly horizontal and directed to the southwest and west (Plexus Phase I/II ESA, 2004) Describe any evidence of a fluctuating water table or a seasonal high water table (e.g., mottling, saturated soil color or gleyed soils, monitoring well observations). Also, from other sources of information describe the range of natural water table fluctuations in the area. Groundwater levels vary widely across the Site based on the Quaternary soil distribution. Perched groundwater was encountered as shallow as 1 to 2 feet below ground in the north central portion of the Site (Section 1017). Groundwater fluctuation likely occurs in Unit 1 (Lacustrine deposits) in connection with significant recharge events (precipitation and snow melt) based on direct surface water infiltration. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

20 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 18 Extent and Magnitude of Soil Contamination 1.15 Were soil borings conducted in or adjacent to the following source areas? Dispensers yes no not present Piping yes no not present Transfer areas yes no not present Remote fill pipes yes no not present UST basins yes no not present Valves yes no not present AST basins yes no not present Known spill areas yes no not present 1.16 Horizontal Definition: Based on requirements described in Guidance Document 4-01, were a sufficient number of soil borings completed to define the horizontal extent of soil contamination in all directions? Yes No 1.17 Vertical Definition: Based on requirements described in Guidance Document 4-01, were all soil borings completed to the required depth? Yes No 1.18 Site Stratigraphy: Based on requirements described in Guidance Document 4-01, was the stratigraphy boring completed to the required depth? Yes No If you answered NO to any of the four previous questions, explain why the borings were not conducted in the required locations or to the required depths. See Guidance Document 4-01 Soil and Ground Water Assessments Performed during Site Investigations regarding exceptions and MPCA approval for depth of drilling Describe the vertical and horizontal extent and magnitude of soil contamination based on field observations, soil headspace measurements (Table 2), and soil analytical results (Tables 3 and 4). If non-petroleum contaminants are present, discuss the possible sources of these compounds. Provide a map and two cross sections that illustrate both soil headspace and laboratory analytical results in Section 4. Include laboratory analytical reports and soil sampling methodology in Section 6. No field evidence (soil staining, elevated (above 10) PID readings or petroleum saturated soils) or laboratory analytical evidence of petroleum contaminated soil was identified in Sections 1001, 1003, 1005, 1007, 1011, 1015, 2003, 4001, 4004, 4005, 4006 and 4009 based on the Site investigation work completed by AECOM in December 2010 and January/May Field evidence and/or laboratory analytical evidence of petroleum contaminated soil was identified in Sections 1008, 1010, 1012, 1017, 3002, 3008, 4007 and PID headspace readings collected from soil borings are summarized on Table 2 and are listed on the soil boring logs attached in Appendix E. A summary of the detectable petroleum compounds and sample locations are also shown on Figures 4 through 8. The extent and magnitude of petroleum contaminated soil encountered during the LSI is discussed by Section below. Section 1008 (Building 111 Figure 6) Possible petroleum soil contamination consisting of DRO was identified during the Tetra Tech RI in 2007 near an underground sewer line. AECOM completed five soil borings (SI-1008-B23 through Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

21 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 19 SI-1008-B27) to a depth of 15 feet in the immediate vicinity of the underground sewer line to determine the extent and magnitude of possible petroleum contamination. No field evidence of petroleum contamination was identified in soil borings SI-1008-B23 through SI-1008-B27. Analytical soil samples were collected from each boring from just above the observed water table interface (3.5 ft to 7 ft) for analysis of VOC, GRO and DRO. No VOC, GRO or DRO compounds were detected in soil samples SI-1008-B23 (6 ft), SI-1008-B24 (3.5 ft), SI-1008-B25 (7 ft) and SI-1008-B27 (5 ft). DRO was detected in soil sample SI-1008-B26 (5.5 ft) at a concentration of 16.4 mg/kg. Section 1010 (Buildings 112 and 114 Figure 4) Five soil borings (SI-1010-B43 through SI-1010-B47) were completed to further determine the extent and magnitude of petroleum contamination in the former tank farm area previously investigated under Leak number Soil boring SI-1010-B47 was advanced just south of Building 114 where possible petroleum contamination was identified by Tetra Tech in Four soil borings (SI B43 through SI-1010-B46) were advanced around SI-1010-B47 within the former tank farm area to define the horizontal extent of petroleum contamination. Soil boring SI-1010-B47 was advanced to a depth of 35 feet to determine the vertical extent of contamination. Soil borings SI-1010-B43 through SI-1010-B45 were advanced to depths of 11 feet and soil boring SI-1010-B46 was advanced to 7 feet. No field evidence of petroleum contamination was identified in the five soil borings completed by AECOM in Section No VOC, GRO or DRO compounds were detected in soil samples collected from soil borings SI-1010-B43, SI-1010-B45 and SI-1010-B46. No VOC or GRO compounds were detected in soil samples from borings SI-1010-B44 and SI-1010-B47. DRO was detected in soil samples SI-1010-B44 (6 ft) and SI-1010-B47 (5.5 ft) at concentrations of 11 mg/kg and 16.3 mg/kg, respectively. Section 1012 (Former Fuel Farm Figure 6) Five soil borings (SI-1012-B35 through SI-1012-B39) were completed to further determine the extent and magnitude of petroleum contamination in the former fuel farm area previously investigated under Leak number Investigation by Tetra Tech in 2007 identified possible petroleum contamination east of Building 158 (former oil pump house) and near former Tank 25. Soil boring SI-1012-B37 was advanced to a depth of 35 feet to determine the vertical extent of contamination. Soil borings SI-1012-B35, SI-1012-B38 and SI-1012-B39 were advanced to 11 feet and soil boring SI-1012-B36 was advanced to a depth of 15 feet. No field evidence of petroleum contamination was identified in the five soil borings completed by AECOM for the former fuel farm area. Analytical soil samples were collected from just above the observed water table interface for analysis of DRO. No DRO was detected in soil samples SI-1012-B35 (5 ft), SI-1012-B37 (5 ft), SI-1012-B38 (4 ft) and SI-1012-B39 (4.5 ft). DRO was detected in soil sample SI-1012-B36 (4.5 ft) at a concentration of 4,440 mg/kg. The down-gradient horizontal extent of petroleum contamination is generally defined by soil boring SI-1003-B34 located approximately 300 feet down-gradient (southwest) of soil boring SI-1012-B36. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

22 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 20 Section 1017 (Figure 4) Six soil borings (SI-1017-B48(A), SI-1017-B49, SI-1017-B50 and SI-1017-B65 through SI-1017-B67) were completed to determine the extent and magnitude of impacts associated with three former ASTs (Tanks 3, 4 and 5). Soil boring SI-1017-B48(A) was advanced to a depth of 18 feet in the immediate vicinity of Tank 5. Soil borings SI-1017-B49 and SI-1017-B50 were advanced to depths of 8 feet in the immediate vicinity of Tanks 4 and 3, respectively. Elevated PID headspace readings were observed from 2 feet to 4 feet (81 PID units) and 4 feet to 6 feet (122 PID units) in soil boring SI-1017-B48. A soil sample (SI-1017-B48 (6 ft)) collected from the highest PID reading had a GRO concentration of 870 mg/kg and a DRO concentration of 3,750 mg/kg. Sec-butyl benzene (1.31 mg/kg), p-isopropyltoluene (1.31 mg/kg), n-propylbenzene (0.131 mg/kg), 1,2,4-trimethylbenzene ( mg/kg) and 1,3,5-trimethylbenzene (0.410 mg/kg) were also detected in soil sample SI-1017-B48 (6 ft). No other VOC compounds were detected in soil sample SI-1017-B48 (6 ft). AECOM returned to the Site on May 12, 2011 to further define the extent of petroleum contaminated soil around SI-1017-B48 by completing three additional soil borings (SI-1017-B65 through SI B67). Soil borings SI-1017-B65 through SI-1017-B67 were advanced to depths of 15 feet. No field evidence of petroleum contamination was observed in soil borings SI-1017-B65 through SI-1017-B67 and no BTEX, GRO or DRO compounds were detected in the soil samples (SI-1017-B65 (1.8 ft), SI-1017-B66 (4 ft) and SI-1017-B67 (1 ft) collected from the definition borings. No field evidence of petroleum contamination was observed in soil borings SI-1017-B49 and SI B50. No VOC, GRO or DRO compounds were detected in soil samples SI-1017-B49 (3 ft) and SI B50 (3 ft). Section 3002 (Building 717 Figures 5 and 6) No former USTs or ASTs were identified in Section Surface soil sampling conducted during the Plexus Phase I/II ESA identified DRO contamination in the northeast corner of this Section. AECOM completed one soil boring (SI-3002-B42) to a depth of 7 feet to determine the vertical extent of impacts and four surface soil assessment borings (SI-3002-SS52 through SI-3002-SS55) to determine the horizontal extent of soil contamination. No field evidence of petroleum contamination was observed in the soil boring or the four surface soil assessment borings. No VOC or GRO compounds were detected in soil sample SI-3002-B42 (1 ft). DRO was detected at 176 mg/kg in soil sample SI-3002-B42 (1 ft). The extent of petroleum contamination in Section 3002 appears to consist of low level DRO in the upper one foot of soil in the vicinity of soil boring SI-3002-B42. Section 3008 (IRP Site C Figure 5) A former oil filling station was located in the southwest portion of Section 3008 in 1941 according to the Plexus Phase I/II ESA and the Tetra Tech 2007 RI indicated possible shallow (5 ft to 6 ft) DRO petroleum contamination in the vicinity of the former oil filling station. AECOM completed five soil borings (SI-3008-B51 through SI-3008-B55) to a depth of 11 feet to determine the extent and magnitude of petroleum contamination in this area. No field evidence of petroleum contamination was observed in soil borings SI-3008-B51 through SI-3008-B55. Soil samples were collected from each boring just above the water table for analysis of VOC, GRO and DRO. No VOC or GRO compounds were detected in the soil samples. No DRO Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

23 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 21 compounds were detected in soil samples SI-3008-B53 through SI-3008-B55. Low level DRO was detected in soil samples SI-3008-B51 (4.5 ft) and SI-3008-B52 (5.5 ft) at concentrations of 63.1 mg/kg and 23.3 mg/kg, respectively. Possible petroleum soil contamination (DRO) was encountered during the 2007 Tetra Tech RI at two locations north and northeast of the former oil filling station. AECOM completed two soil borings (SI B56 and SI-3008-B57) and eight surface soil assessment borings (SI-3008-SS44 through SI SS51) to determine the extent of petroleum soil contamination in Section No field evidence of petroleum contamination was identified in soil borings SI-3008-B56 and SI B57 or in surface soil assessment borings SI-3008-SS44 through SI-3008-SS51. No VOC or GRO compounds were detected in soil samples SI-3008-B56 (4 ft) and SI-3008-B57 (3 ft). Low level DRO was detected in SI-3008-B56 (4 ft) and SI-3008-B57 (3 ft) at concentrations of 33.3 mg/kg and 81.1 mg/kg, respectively. The extent of petroleum soil contamination in Section 3008 consists of low level DRO impacts in the upper 5 feet of soils in the vicinity of soil borings SI-3008-B51, SI-3008-B52, SI-3008-B56 and SI B57 based on Site investigation completed to date. Section 4007 (Former Building 501 Figure 8) Two former USTs (Tanks 38 and 39) and two former ASTs (Tanks 35 and 36) were located in Section The former UST and AST locations were investigated during the Plexus Phase I/II ESA and no evidence of petroleum contamination was identified at the UST and AST locations. The Plexus Phase I/II ESA identified DRO above 50 mg/kg in four surface soil samples collected around former Building 501. AECOM completed a soil boring in the immediate vicinity of each of the four surface soil sample locations where DRO above 50 mg/kg was identified during the Plexus Phase I/II ESA. Soil boring SI-4007-B8 was completed to a depth of 25 feet by AECOM off of the southwest corner of the former building slab along with three surface soil assessment borings (SI-4007-SS11 through SI-4007-SS13). No field evidence of petroleum contamination was identified in the soil boring or surface soil assessment borings. Analytical soil sample SI-4007-B8 (25 ft) was non-detect for VOCs, GRO and DRO. Soil boring SI-4007-B9 was completed to a depth of 26 feet within the footprint of former Building 501 within an approximately 12 foot by 18 foot opening in the concrete floor slab containing soil and vegetation at the same approximate grade elevation as the floor slab. The opening in the floor slab was possibly a former quench oil pit. An elevated PID headspace reading of 26 PID units was observed at a depth of 4 to 6 feet in soil boring SI-4007-B9. The vertical extent of petroleum contamination based on field evidence was 6 feet. Analytical soil samples were collected from the highest PID reading zone (SI-4007-B9 (4.5 ft)) and at the base of the boring (SI-4007-B9 (25 ft)). Soil sample SI-4007-B9 (4.5 ft) had detections of DRO (134 mg/kg), GRO (13.6 mg/kg), naphthalene (0.356 mg/kg) and styrene ( mg/kg). No VOC, GRO or DRO compounds were detected in the soil sample collected from the base of the soil boring (SI-4007-B9 (25 ft)). Soil boring SI-4007-B10 was completed to a depth of 19 feet off the western corner of the former building slab along with three surface soil assessment borings (SI-4007-SS14 through SI-4007-SS16). No field evidence of petroleum contamination was identified in the soil boring or surface soil Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

24 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 22 assessment borings. Analytical soil sample SI-4007-B10 (19 ft) was non-detect for VOCs, GRO and DRO. Soil boring SI-4007-B12 was completed to a depth of 16 feet off the northwestern corner of the former building slab along with three surface soil assessment borings (SI-4007-SS10, SI-4007-SS17 and SI-4007-SS18). No field evidence of petroleum contamination was identified in the soil boring or surface soil assessment borings. Analytical soil sample SI-4007-B12 (16 ft) was non-detect for VOCs, GRO and DRO. Section 4008 (Building 502 and IRP Site I Figure 8) One former UST (Tank 40) and six former petroleum ASTs (Tanks 41, 42, 55, 56, 75 and 82) were located in Section Seven soil borings (SI-4008-B1 through SI-4008-B7) and eleven surface soil assessment borings (SI-4008-SS1 through SI-4008-SS9, SI-4008-SS4A and SI-4008-SS5A) were completed by AECOM to further determine the extent of petroleum contamination in Section 4008 associated with the UST and ASTs and possible petroleum soil contamination (DRO) detected in surface soil samples collected by Tetra Tech in Soil boring SI-4008-B1 was advanced to a depth of 50.5 feet in the immediate vicinity of Tank 82. No field evidence of petroleum soil contamination was observed in soil boring SI-4008-B1 and no VOC, GRO or DRO compounds were detected in soil sample SI-4008-B1 (50 ft). Soil boring SI-4008-B2 was completed to a depth of 23 feet off the east side of Building 502 along with three surface soil assessment borings (SI-4008-SS1 through SI-4008-SS3). No field evidence of petroleum contamination was identified in the soil boring or surface soil assessment borings. Analytical soil sample SI-4008-B2 (23 ft) was non-detect for VOCs, GRO and DRO. Five surface soil assessment borings (SI-4008-SS4, SI-4008-SS4A, SI-4008-SS5, SI-4008-SS5A and SI SS6) were completed off the southeast corner of Building 502. Surface soil assessment borings SI-4008-SS4 and SI-4008-SS6 had PID readings greater than 10 PID units at 24 and 11 PID units, respectively. Petroleum/chemical odors were also detected in the surface soils for assessment borings SI-4008-SS4 and SI-4008-SS5. Analytical soil samples were collected from SI-4008-SS4, SI-4008-SS5 and SI-4008-SS6 for DRO analysis based on elevated PID readings and/or odors observed. DRO was detected in SI-4008-SS4 at 1,340 mg/kg, in SI-4008-SS5 at 763 mg/kg and in SI-4008-SS6 at 29.2 mg/kg. Soil boring SI-4008-B3 was advanced to a depth of 22 feet in the immediate vicinity of SI-4008-SS4 to determine the vertical extent of impacts at this location. No elevated PID readings were observed in soil boring SI-4008-B3; however, a chemical odor was detected at a depth of 3 feet in this boring and an analytical soil sample collected from 2 feet at this location had a DRO concentration of 2,330 mg/kg. A soil sample collected at a depth of 22 feet in soil boring SI-4008-B3 was non-detect for DRO as well as benzene, toluene, ethylbenzene and xylenes (BTEX). Cis-1,2-dichloroethene ( mg/kg), 1,1,1- trichloroethane (0.246 mg/kg) and trichloroethene (0.689 mg/kg) were detected in soil sample SI B3 (22 ft). AECOM returned to the Site on May 11, 2011 to further determine the horizontal extent of surface soil contamination in Section Two surface soil assessment borings (SI-4008-SS4A and SI SS5A) were completed east and south of SI-4008-SS4 and SI-4008-SS5, respectively. No evidence of surface soil contamination was observed in surface soil assessment borings SI-4008-SS4A and SI SS5A. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

25 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 23 Laboratory Analytical Summary for Soil Samples Laboratory analytical soil samples were analyzed for VOC, GRO and DRO. Laboratory analytical results for the soil samples collected are summarized on Tables 3 and 4. Laboratory analytical reports are included in Appendix F. No BTEX or MTBE compounds were detected in the soil samples analyzed from the Site for the LSI. GRO was detected in three soil samples including SI-1017-B48 (870 mg/kg), SI-4007-B9 (13.6 mg/kg) and SI-4008-B7 (12.4 mg/kg). DRO was detected in fifteen soil samples including SI-4008-SS4 (1,340 mg/kg), SI-4008-SS5 (763 mg/kg), SI-4008-SS6 (29.2 mg/kg), SI-4008-B3 (2,330 mg/kg), SI-4007-B9 (134 mg/kg), SI-1008-B26 (16.4 mg/kg), SI-2012-B36 (4,440 mg/kg), SI-3002-B42 (176 mg/kg), SI-1010-B44 (11 mg/kg), SI B47 (16.3 mg/kg), SI-1017-B48 (3,750 mg/kg), SI-3008-B51 (63.1 mg/kg), SI-3008-B52 (23.3 mg/kg), SI B56 (33.3 mg/kg) and SI-3008-B57 (81.1 mg/kg). 1,2,4-trimethylbenzene (0.286 mg/kg) and 1,3,5-trimethylbenzene (0.410 mg/kg) were detected in soil sample SI-1017-B48 (6 ft.) along with sec-butylbenzene (1.31 mg/kg), p-isopropyltoluene (1.31 mg/kg) and n-propylbenzene (0.131 mg/kg). Naphthalene (0.356 mg/kg) and styrene ( mg/kg) were detected in soil sample SI-4007-B9 (4.5 ft.). Cis-1,2 dichloroethene (DCE) was detected in soil sample SI-4008-B7 at a concentration of mg/kg which is above the Tier 1 soil leaching value (SLV) of 0.14 mg/kg and in soil sample SI-4008-B3 (22 ft.) at a concentration of mg/kg. Trichloroethene (TCE) was detected in soil sample SI-4008-B3 (2 ft.) at a concentration of mg/kg and in soil sample SI-4008-B3 (22 ft.) at a concentration of mg/kg which is above the established Tier 1 SLV of 0.14 mg/kg. The presence of non-petroleum compounds is likely associated with historic small arms ammunition manufacturing processes conducted at the Site Is contaminated soil in contact with ground water? Yes No Contaminated soil was identified at the approximate groundwater interface (saturated soil conditions) in Sections 1010, 1012, 1017, 3002 and 3008 based on analytical soil samples collected from soil borings and field evidence of petroleum contamination. The depth to ground water in these Sections ranged from one foot in Sections 1017 and 3002 to approximately six feet in Section If YES, or if ground water contamination appears likely, then complete the Aquifer Determination section below. If NO, complete question a) What is the distance separating the deepest contamination from the surface of the water table? Not Applicable contaminated soil is in contact with groundwater at the Site. b) Was this distance measured during site activities, referenced from geologic information, or estimated based on professional opinion during a site visit? Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

26 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 24 c) In your judgment, is there a sufficient distance separating the petroleum contaminated soil from the underlying aquifer to prevent contamination of the aquifer? Yes No Please explain in detail. In your explanation, consider the site-specific geology, the data in this section, and the nature of the petroleum release (i.e., volume, age, released product type). If YES, the Aquifer Determination is not necessary as part of the LSI. If NO, complete the Aquifer Determination section below Is contaminated surface soil (0-2 feet) present at the site? Yes No If YES, delineate the extent of contaminated surface soil, identify the extent(s) of contaminated surface soil on a Site Map, and propose a corrective action in Section 3 to mitigate the impacts. If borings were used to define the extent, complete Table 5. See Guidance Document 3-01 Excavation of Petroleum Contaminated Soil and Tank Removal Sampling for more information regarding contaminated surface soil identification, delineation, and excavation. AECOM completed surface soil assessment borings at 57 locations throughout the Site. The surface soil assessment locations are illustrated on Figures 3 through 8. Surface soil assessment borings consisted of sampling the upper 2 feet of soil with a push probe. Information obtained at the surface soil assessment borings as well as the upper 2 feet of the soil borings included PID headspace readings, field screening for visual evidence of soil staining and dead vegetation and completion of a petroleum sheen test in accordance with MPCA Guidance Document 4-04 to determine if soils were petroleum saturated. The results of the petroleum sheen tests did not indicate the presence of petroleum saturated soils at the surface soil sample locations. A summary of surface soil assessment results is included on Table 5A and surface soil assessment results for the soil borings is included on Table 5B. No evidence of surface soil contamination was observed in Sections 1001, 1003, 1005, 1007, 1008, 1009, 1010, 1011, 1012, 1015, 1017, 2003, 3008, 4001, 4004, 4005, 4006, 4007 and Contaminated surface soil was encountered in the southeast portion of Section 4008 off of the southeast corner of Building 502 and near a former rail line (see Figure 8). Surface soil assessment borings SI-4008-SS4 and SI-4008-SS6 had PID readings greater than 10 PID units at 24 and 11 PID units, respectively. Petroleum/chemical odors were also detected in the surface soils for assessment borings SI-4008-SS4 and SI-4008-SS5. Analytical soil samples were collected from SI-4008-SS4, SI SS5 and SI-4008-SS6 for DRO analysis based on elevated PID readings and/or odors observed. DRO was detected in SI-4008-SS4 at 1,340 mg/kg, in SI-4008-SS5 at 763 mg/kg and in SI-4008-SS6 at 29.2 mg/kg. Soil boring SI-4008-B3 was advanced in the immediate vicinity of SI-4008-SS4 to determine the vertical extent of impacts at this location. No elevated PID readings were observed in soil boring SI-4008-B3; however, a chemical odor was detected at a depth of 3 feet in this boring and an analytical soil sample collected from 0 to 2 feet at this location had a DRO concentration of 2,330 mg/kg. A soil Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

27 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 25 sample collected at a depth of 22 feet in soil boring SI-4008-B3 was non-detect for DRO as well as BTEX and MTBE. AECOM returned to the Site on May 11, 2011 to further determine the horizontal extent of surface soil contamination in Section Two surface soil assessment borings (SI-4008-SS4A and SI SS5A) were completed east and south of SI-4008-SS4 and SI-4008-SS5, respectively. No evidence of surface soil contamination was observed in surface soil assessment borings SI-4008-SS4A and SI SS5A. The approximate area of surface soil contamination observed in Section 4008 is illustrated on Figure 8. DRO (176 mg/kg) was detected at a depth of one foot below ground in soil boring SI-3002-B42. The soil sample was collected at the water table interface (one foot) and soils encountered at this location consisted of organic silts. No elevated PID readings, soil staining or petroleum saturated soils were observed at this location. Four surface soil assessment borings (SI-3002-SS52 through SI-3002-SS55) were completed in the immediate vicinity of soil boring SI-3002-B42 and no evidence of surface soil contamination was observed. The initial round of investigation work was completed in December 2010 when the ground surface was covered with snow. AECOM returned to the Site on May 9, 2011 to conduct a walking surface soil assessment to observe for the presence of surface soil staining or areas of dead or stressed vegetation which may be indicative of a surface soil release. AECOM observed the ground surface at each soil boring and surface soil boring location completed for the LSI. A lack of vegetation was observed in the immediate vicinity of AECOM soil boring SI-4008-B48 which was completed near former Tank 5 (300 gallon diesel AST). A lack of vegetation was observed south of boring SI-1012-B36 located in the former tank farm area in Section No elevated PID readings or soil staining were observed in the surface soil sample collected at this location. The ground surface around soil boring SI-1005-B22 had limited vegetation consisting mostly of moss. No elevated PID headspace readings or soil staining was observed at this location. No evidence of a surface release including soil staining, elevated PID headspace readings or dead or distressed vegetation was observed at the other investigation areas observed by AECOM. Corrective action associated with petroleum contaminated surface soils encountered at the Site is not recommended at this time based on the current Site use as a vacant industrial property. The Site is currently vacant and Site access is secured and controlled by the U.S. Army. The risks associated with identified petroleum contaminated surface soils are low based on the extent and magnitude of contamination identified and the current Site usage. Corrective action associated with petroleum contaminated surface soils may be required if the Site usage changes. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

28 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 26 Aquifer Determination Grain size analysis for aquifer determination was not conducted under this scope of work. The two hydrogeologic units likely encountered during the LSI borings included Unit 1 (Lacustrine Deposits) and Unit 2 (Twin Cities Formation). Unit 1 and Unit 2 at the Site do not meet the MPCA definition of an aquifer based on the calculated transmissivity values (see Section 1.12 below). The primary resource aquifers utilized for water supply in this area consist of the Prairie du Chien/Jordan and Mount Simon/Hinckley bedrock aquifers. See Section 1.12 for a discussion regarding the local and regional hydrogeology. Complete this section if ground water has been contaminated or may become contaminated based on questions 1.20 and Aquifer determination is made during the LSI. It is based upon the stratigraphy and a hydraulic conductivity measurement calculated from grain size analyses. The site stratigraphy gives the context within which the hydraulic conductivity measurement can be interpreted. Please refer to Guidance Document 4-01 Soil and Ground Water Assessments Performed during Site Investigations for methods and requirements. Provide the results of grain size analyses, calculations, and other information used for the determination of hydraulic conductivity in Section 6. Determine the aquifer thickness (b) from geologic logs of soil borings, water well logs, and available published information Calculate an average hydraulic conductivity value (K). Unit 1 (silty sand, fine sand) - K = 10-4 cm/sec = ft/day Unit 2 (clay) - K = 10-5 cm/sec = ft/day Indicate the calculation method (e.g. Hazen, Masch and Denny, Kozeny-Carmen, etc.). The hydraulic conductivities were referenced from Applied Hydrogeology, 3 rd Edition, by: C.W. Fetter, 1994 based on a soil type of fine sand, silty sand (Unit 1) and clay (Unit 2) Calculate a range for aquifer transmissivity (T) using the equation T = Kb, where b is the thickness of the aquifer. For Unit 1 - Lacustrine Deposits T High = ft/day*40 ft = 11 ft 2 /day- thickness (b) is the estimated maximum thickness of saturated Unit 1 from published information (Stone, 1966) and observed water levels in the LSI borings. T Low = ft/day*10 ft = 3 ft 2 /day- thickness (b) is the estimated minimum thickness of saturated Unit 1 from published information (Stone, 1966) and observed water levels in the LSI borings. For Unit 2 - Twin Cities Formation T High = ft/day*110 ft = 3 ft 2 /day thickness (b) is the estimated maximum thickness of the Twin Cities Formation from published information (Stone, 1966). T Low = ft/day*30 ft = 1 ft 2 /day - thickness (b) is the estimated minimum thickness of the Twin Cities Formation from published information (Stone, 1966). Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

29 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 27 If the transmissivity of a contaminated hydrogeologic unit is greater than 50 ft 2 /day, it is considered an aquifer for the purpose of the Petroleum Remediation Program. If the hydrogeologic unit meets the definition of an aquifer, then monitoring wells are required if any of the following conditions are met: 1) ground water is impacted at or above Minnesota Department of Health (MDH) Health Risk Limits (HRLs) or 1,000 µg/l GRO or DRO; 2) ground water is impacted below the HRLs but levels are likely to reach the HRLs; or 3) there is an insufficient distance separating the petroleum contaminated soil (or an impacted non-aquifer) from an underlying aquifer. If monitoring wells were installed complete the Aquifer Characterization section below as part of an RI. The estimated transmissivity values for hydrogeologic Unit 1 (Lacustrine Deposits) and Unit 2 (Twin Cities Formation) are less than 50 ft 2 /day. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

30 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 28 Aquifer Characterization Aquifer Characterization was not Completed Under the MPCA Requested Scope of Work 1.25 Discuss the drilling and installation of monitoring wells including the rationale for their locations. Summarize their construction in Table 9. Attach boring logs, well construction diagrams, and well logs in Section Is there a clean or nearly clean (below HRLs) downgradient monitoring well located along the longitudinal axis of the contaminant plume (approximately 20 degrees plus or minus the axis)? 1.27 Is there a worst case well completed through the source area(s) of the release? Yes Yes No No If you answered NO to any of the above two questions, please explain why a well was not completed in the required location Provide an estimate of the longitudinal length of the dissolved contaminant plume: feet Calculate ground water flow velocity (based on Darcy's Law) using the average hydraulic conductivity (K), average horizontal hydraulic gradient (dh/dl), and effective porosity (n). Provide documentation and show calculations in Section 6. Hydraulic conductivity (K) = ft/day (Method if different than that used in 1.23: ) Porosity (n) = method/reference Average horizontal gradient (dh/dl) = (unitless) Calculated ground water velocity (v) = ft/day 1.30 Using the calculated ground water flow velocity from question 1.29, is there a receptor(s) located within a five-year travel time from the source area? If YES, describe the location and type of receptor(s) Were any deep monitoring wells completed at the site? Yes No If YES, list them and indicate their depths: Yes No Contact the MPCA project hydrologist before installing a deep monitoring well. A deep monitoring well may be necessary if: 1) contamination exists more than 10 feet below the water table or 2) the impacted aquifer is a drinking water aquifer or is hydraulically connected to the aquifer(s) presently used by a water supply well located within 500 feet of the release source. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

31 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 29 If contamination is present at depth in the aquifer or in deeper aquifers, additional deep wells may be required. Provide the following information if deep wells were installed: Vertical gradient (dv/dl) Inferred ground water flow direction Provide the following information for the deep aquifer unit if it appears to be hydrogeologically distinct from the upper unit. Porosity (n): Hydraulic conductivity (K) ft/day Submit this RI report after completing a minimum of two quarterly sampling events. Quarterly ground water monitoring and sampling should continue until MPCA response is received. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

32 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 30 Extent and Magnitude of Ground Water Contamination 1.32 Describe the extent and magnitude of ground water contamination based on the analytical results of samples collected as part of an LSI (Tables 6, 7, and 8) and, if applicable, monitoring well samples collected as part of an RI (Tables 10, 11, and 12). Provide Site Maps that illustrate both the laboratory analytical results and, if applicable, ground water gradients in Section 4. Groundwater sampling for the LSI was limited as significant groundwater investigation and contaminant delineation were conducted at the Site during previous Site investigations. AECOM collected groundwater samples from temporary monitoring wells in Sections 1017 and 2003 (see Figure 4A). Groundwater analytical results are summarized on Tables 6, 7 and 8 and summarized on Figure 4A. Temporary well/soil boring locations are illustrated on Figures 3 and 4A. Groundwater sampling methodologies and procedures are described in Appendix G. Sampling information forms documenting the groundwater sampling activities are included in Appendix H. Results of groundwater sampling are summarized by Section below. Section 1017 No groundwater sampling was proposed for Section 1017; however, field and laboratory evidence of petroleum contamination was identified in the shallow Site soils at soil boring SI-1017-B48 in the location of a former 300 gallon diesel AST (Tank 5). Contaminated soil (approximately 2 to 6 feet below ground) was in direct contact with groundwater at soil boring SI-1017-B48 and no evidence of previous groundwater investigation was identified at this location. AECOM discussed the petroleum impacts identified with the Mr. Mark Koplitz (MPCA Project Manager) and Mr. Tom Higgins (MPCA Project Hydrogeologist) and the MPCA requested additional temporary wells/soil borings to determine the extent and magnitude of groundwater as well as soil contamination at this location. AECOM returned to the Site on May 11-12, 2011 to advance four temporary monitoring wells/soil borings (SI-1017-B48A, SI-1017-B65, SI-1017-B66 and SI-1017-B67) to determine the extent and magnitude of soil and groundwater contamination around Tank 5. The extent of groundwater petroleum contamination identified above established health risk limits (HRLs), health based values (HBVs) and risk assessment advice (RAA) was limited to temporary well/soil boring SI-1017-B48(A) located in the immediate vicinity of Tank 5. Groundwater analytical results for Section 1017 are summarized below. Groundwater Sample SI-1017-B48A - GRO (1,140 µg/l) and DRO (3,300 µg/l) were detected above the established HBV for total petroleum hydrocarbons (TPH) of 200 µg/l. Naphthalene (99 µg/l) was detected above the established HBV for this compound of 70 µg/l. 1,2,4 trimethylbenzene (105 µg/l) was detected above the established RAA for this compound of 100 µg/l. Ethylbenzene (20.0 µg/l), total xylenes (36.0 µg/l), 1,3,5 trimethylbenzene (65.7 µg/l), isopropylbenzene (7.5 µg/l), n-butylbenzene (9.2 µg/l), n-propylbenzene (14.4 µg/l), p-isopropyltoluene (14.5 µg/l), sec-butylbenzene (10.5 µg/l) and tertbutylbenzene (1.1 µg/l) were identified at concentrations below established HRLs, HBVs or RAAs for these compounds if available. Groundwater Sample SI-1017-B488 (duplicate of SI A) This duplicate sample had comparable results to sample SI-1017-B48A. GRO (1,330 µg/l) and DRO (4,000 µg/l) were detected above the established HBV for TPH of 200 µg/l. Naphthalene (81.2 µg/l) was detected above the established HBV for this compound of 70 µg/l. Ethylbenzene (14.4 µg/l), total xylenes (27.2 µg/l), 1,2,4- trimethylbenzene (89.5 µg/l), 1,3,5 trimethylbenzene (58 µg/l), isopropylbenzene (6.1 µg/l), n- Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

33 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 31 butylbenzene (8.6 µg/l), n-propylbenzene (12.2 µg/l), p-isopropyltoluene (12.9 µg/l) and secbutylbenzene (9.3 µg/l) were identified below established HRLs, HBVs or RAAs for these compounds if available. Groundwater Sample SI-1017-B65 - No VOC, GRO or DRO compounds were detected above laboratory reporting limits in groundwater sample SI-1017-B65. Groundwater Sample SI-1017-B66 - DRO (140 µg/l) was detected below the established HBV of 200 µg/l for TPH. No VOC or GRO compounds were detected above laboratory reporting limits in groundwater sample SI-1017-B66. Groundwater Sample SI-1017-B67 - Trichloroethene (4.1 µg/l) was detected below the established HRL of 5 µg/l for this compound. No petroleum VOC compounds, GRO or DRO compounds were detected above laboratory reporting limits in groundwater sample SI-1017-B67. Section 2003 (Former Housing Area) Three temporary wells/soil borings (SI , SI and SI ) were completed in the former housing area to determine the potential for petroleum contamination to groundwater associated with 14 ASTs (Tanks 57, 58 and 60 through 71) and 1 UST (Tank 59) formerly located in this area. The former housing area is located up-gradient of a nearby surface water receptor (Rice Creek). The groundwater samples (SI (W), SI (W) and SI (W)) were analyzed for VOCs and DRO as the UST and ASTs in this area historically contained heating oil. No VOC or DRO compounds were detected in the groundwater samples collected from Section The risks associated with petroleum groundwater contamination in Section 2003 appear low based on the results of the groundwater sampling completed by AECOM If non-petroleum contaminants are present, discuss the possible sources of these compounds. Trichloroethene was detected in groundwater sample SI-1017-B67 below the established HRL. Chlorinated solvents were historically utilized at the Site during production of small arms ammunition. The extent and magnitude of chlorinated solvent contamination at the Site was investigated and ongoing groundwater remediation is being conducted associated with chlorinated compound contamination Provide a discussion on QA/QC, including information on the samples collected and laboratory analyses performed. Include laboratory analytical reports and ground water sampling methodology in Section 6. A blind duplicate groundwater sample (SI ) was collected at temporary monitoring well/soil boring SI A for analysis of VOC, GRO and DRO. The analytical results of the blind duplicate sample were generally comparable to the results of the original groundwater sample (SI A). A trip blank was analyzed for VOC during the December, 2010 groundwater sampling and for VOC and GRO during the May, 2011 groundwater sampling. No VOC or GRO compounds were detected in the trip blank samples from either groundwater sampling event. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

34 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 32 The equipment used to collect groundwater samples was disposable and new sampling equipment (i.e. peristaltic tubing) was used at each groundwater sample location. Therefore, no field equipment blanks were obtained during the groundwater sampling Laboratory certification number: Pace Analytical - MDH Certification # Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

35 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 33 Evaluation of Natural Attenuation Natural Attenuation Evaluation was not Conducted Under the MPCA Requested Scope of Work Refer to the Guidance Document 4-03 Assessment of Natural Attenuation at Petroleum Release Sites. Note: Evaluation of natural attenuation is not required unless requested by MPCA staff Discuss the results of the natural attenuation assessment (Table 13). Specifically, compare the concentrations of the inorganic parameters inside and outside the plume and whether the data indicate natural biodegradation is occurring at the site If active remediation is anticipated, discuss reasons why natural attenuation (including biodegradation) cannot adequately remediate the contaminants to acceptable risk levels. Extent and Recovery of Free Product If free product is encountered during the investigation, include Guidance Document 2-03 Free Product Recovery Report Worksheet in Section 6. See Guidance Document 2-02 Free Product: Evaluation and Recovery for additional information If free product was encountered during the site investigation, describe the work completed to delineate the extent of the free product zone and what efforts were or are being completed to recover it. Tabulate the volume of product recovered in Table 14. Illustrate the estimated horizontal extent of the free product zone on a Site Map in Section 4. No visible or measurable free product was observed and no evidence of petroleum saturated soils based on the MPCA petroleum sheen test (Guidance Document 4-04) were observed during the LSI performed by AECOM. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

36 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 34 Section 2: Risk Assessment Well Receptors List all properties located within 500 feet of the site in Table 15. Identify all properties listed in Table 15 on the Potential Receptor Map in Section 4. List all wells located within 500 feet of the site and any municipal or industrial wells within ½ mile in Table 16. All water wells within 500 feet of the release source must be listed even if construction information was not obtained or available. Include all available water supply well logs obtained from Minnesota Geological Survey, MDH, drillers, or county well management authorities, and any other well construction documentation in Section 6. Identify all wells listed in Table 16 on the Well Receptor Survey Map in Section Were all property owners within 500 feet of the site successfully contacted to determine if water wells are present? If NO, please explain. Yes No 2.2 Discuss any physical limitation to the inspection of properties within the 500-foot survey radius. No physical limitations to the inspection of the property were encountered. 2.3 Discuss the results of the ground water receptor survey. Comment on the risks to water supply wells identified within 500 feet from the site as well as the risk posed by or to any municipal or industrial wells found within ½ mile. Specifically indicate whether identified water supply wells use the impacted aquifer. (Note: an impacted aquifer separated from another aquifer by a clay lens may not be considered a separate aquifer). AECOM reviewed the MDH county well index (CWI) database along with previous reports for the Site and interviewed representatives from the U.S. Army (Mr. Mike Fix), the City of New Brighton (Mr. Dave Olson) and the City of Arden Hills (Mr. Terry Maurer) to determine the location and status of water supply wells in the vicinity of the Site. Seven abandoned industrial supply wells (unique numbers , , , , , and ) associated with former TCAAP operations were identified on or near the 585-acre transfer property. Unique well (TCAAP AM-4) is listed as a commercial well on the MDH well log and was located on the western portion of the Site on the northeast quadrant of County Road H and Highway 35W. Well number was sealed by Keys Well Drilling Co. on June 11, 1987 according to a Well Abandonment Report prepared by Keys (attached in Appendix K). An MDH well sealing record for this well was not identified. Unique well number (Federal Cartridge Co.) is listed as a domestic well according to the MDH well log and was located north of the Site but on TCAAP property. Unique well was sealed on December 17, Unique well (ST-14- U3/03U014) is listed as a domestic well on the MDH well log and is located east of Section 4006 on TCAAP property. The well was installed in 1982 and is utilized as a monitoring well according to U.S. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

37 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 35 Army records. The former locations of the water supply wells are illustrated on Figure 12. Copies of the well logs and available well sealing records for the above wells are included in Appendix K. A public supply non-community transient well (Unique number ) associated with the Big Ten Supper Club (Big Ten) is located approximately 500 feet southwest of the TCAAP Gate 4 entrance across Highway 10. The Big Ten well is 286 feet deep and is cased to a depth of 250 feet below ground. The risks to Unique well from Leak appear low based on the extent and magnitude of petroleum contamination and the well construction information. A copy of the water supply well log for Unique number is included in Appendix K. Two public supply/non-community water supply wells (Unique numbers and ) associated with the Arden Manor Mobile Home park were located approximately 1,000 feet southwest of the Site across Highway 10. U.S. Army records indicate that the U.S. Army provided the property owner for Arden Manor Mobile Home park assistance in sealing the water supply wells and connecting the property to the City of Arden Hills municipal water supply in October, Unique well is listed as abandoned on the MDH well log. Well sealing records for unique wells and were not identified. The well logs for these wells are included in Appendix K. No municipal supply wells were identified within 1/2 mile of the release Site(s). The nearest City of New Brighton municipal supply well (Well #12, Unique number ) is located approximately 1.5 miles west to southwest of the Site. A City of Mounds View municipal supply well (#5, Unique number ) is located approximately 1 mile west of the Site at 5100 Long Lake Road in Mounds View. The City of Arden Hills purchases treated water for municipal supply from the Saint Paul Regional Water Services. The risk to municipal supply wells in the area from Leak appears low based on the identified extent and magnitude of petroleum contamination and the well construction for the municipal supply wells. Water supply wells in the area generally utilize the Prairie du Chien/Jordan or Mt. Simon/Hinckley resource aquifers. The risk to the Prairie du Chien/Jordan and Mt. Simon/Hinckley resource aquifers from Leak appears low based on the extent and magnitude of petroleum contamination identified. 2.4 If water samples were collected from nearby water wells, discuss the analytical results below and tabulate them in Tables 11 and 12. Water samples from nearby water wells were not collected as part of the LSI. 2.5 Is municipal water available in the area? Yes No 2.6 Based on the public water supply risk assessment, is the site located in a Source Water Assessment Area or Drinking Water Supply Management Area (see Guidance Document 4-18 Public Water Supply Risk Assessment at Petroleum Remediation Sites)? Yes No If YES, provide the name of the area and include the required documentation in Section 6. The Site is located within the City of New Brighton DWSMA. The MDH Source Water Assessment information and DWSMA diagram for New Brighton are included in Appendix L. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

38 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page Are there any plans for ground water development in the impacted aquifer within ½ mile of the site or one mile downgradient of the site if the aquifer is fractured? Yes No Provide the name, title and telephone number of the person that was contacted for this information. Name: Mr. Dave Olson Title: City of New Brighton Public Works Superintendent Telephone: (651) The City of New Brighton has no plans for groundwater development within one mile of the Site according to Mr. Dave Olson, the City of New Brighton Public Works Superintendent. Name: Mr. Terry Maurer Title: City of Arden Hills Public Works Telephone: (651) Arden Hills currently has no plans for groundwater development within one mile of the Site according to Mr. Terry Maurer of the City of Arden Hills Public Works Department. The City of Arden Hills purchases treated water for municipal supply from the Saint Paul Regional Water Services. Name: Ms. Tracy Juell Title: City of Mounds View Water Superintendent Telephone: (763) The City of Mounds View has no plans for groundwater development within one mile of the Site according to Ms. Tracy Juell, the City of Mounds View Water Superintendent. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

39 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 37 Surface Water Receptors 2.8 Are there any surface waters or wetlands located within ¼ mile of the site? Yes No If YES, list them along with their distance and direction from the site in Table 17. Rice Creek flows from north to south near the northwest portion of the Site east and south of the former housing area (Section 2003). An unnamed surface water feature is located in the northeastern portion of the Site adjacent to Section Round Lake is located approximately 600 feet southwest of the Site. The potential surface water receptor locations are illustrated on Figure 11. Also, list below any potential pathways such as ditches, drain tiles, storm sewers, etc., that may lead to the identified surface water features. 2.9 If surface water is present downgradient of the site, is there a clean downgradient soil boring or monitoring well located between the site and the surface water? Yes No NA If YES, identify the clean downgradient boring or well, distance to the surface water feature, and discuss the contamination risk potential. The risks to surface water features identified within 1/4 mile associated with petroleum contamination at the Site are low based on the extent and magnitude of petroleum contamination identified and the proximity of the surface water features to identified release areas. Shallow groundwater contamination was observed in soil boring SI-1017-B48 located up-gradient of Rice Creek in Section Soil borings SI-1017-B66 and SI-1017-B67 were completed between SI B48A and Rice Creek. DRO (140 µg/l) was detected below the established HBV for TPH (200 µg/l) in the groundwater sample collected from SI-1017-B66. No BTEX or GRO compounds were detected in groundwater sample SI-1017-B66. No BTEX, DRO or GRO compounds were detected in groundwater sample SI-1017-B67. No field or analytical evidence of petroleum contamination was detected in the seven soil borings (SI-2003-B58 through SI ) located in Section 2003 north and west of Rice Creek including groundwater samples collected at temporary wells/soil borings SI-2003-B58, SI-2003-B61 and SI B64. The unnamed surface water feature is located in Section 3007 where no evidence of USTs or ASTs was identified and no investigation work was completed by AECOM. The unnamed surface water feature is located up-gradient from identified petroleum contamination areas of the Site. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

40 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 38 No field or analytical evidence of petroleum contamination was detected in soil borings SI-4008-B4 through SI-4008-B6, SI-4007-B8 or SI-4007-B10 located in the southwest portion of the Site up-gradient from Round Lake. If NO, and ground water from a downgradient boring or well is contaminated, we assume that contamination discharges to the surface water. Therefore, provide the following information: Name of receiving water: Plume width, (W): feet Plume thickness, (H): feet Hydraulic conductivity, (K): gal/day/ft 2 Horizontal gradient, (dh/dl): (unitless) Discharge, (Q) = H*W*K*(dh/dl)/1440 gal/min Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

41 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 39 Utilities and Subsurface Structures 2.10 Compare the relationship between the distribution of contaminant phases (soil, ground water, vapor, and non-aqueous phase liquid) to the location of all underground utility lines, utility service lines, and nearby basements and sumps. Include all identified utilities in Table 18. Show all utilities, utility service lines, and other subsurface structures on applicable cross sections in Section 4. Vacant buried utility lines remain at the Site including steam lines, electric lines, storm sewer, sanitary sewer, natural gas lines and communication lines. The risks associated with petroleum contamination migrating to underground utility lines is low based on the limited extent and magnitude of petroleum contaminated soil and groundwater and the lack of receptors associated with the vacant utilities at the Site. The deepest identified evidence of petroleum contamination based on soil and groundwater analytical samples was at a depth of 6 feet in soil boring SI The deepest identified evidence of petroleum contamination based on field evidence (petroleum odors) was to a depth of 12 feet in soil boring SI-4008-B7. No evidence of free product or petroleum contaminated groundwater migrating along utility corridors was identified. Existing groundwater remediation utility lines are located in the southwestern portion of the Site as part of the ongoing Boundary Groundwater Recovery System (BGRS) associated with the deep chlorinated groundwater contamination Is there any evidence that free product or contaminated ground water may be traveling off site within the utility corridors? Yes No If YES, a utility backfill investigation is required (refer to Guidance Document 4-01). Discuss the investigation rationale and results Is there a history of field-detectable vapor impacts in the vicinity of the site? Yes No If YES, describe: Conduct a vapor survey if the vapor receptor survey and risk evaluation indicate a risk of vapor impact or an infiltration risk from contaminated ground water or free product to utilities or subsurface structures. See Guidance Document 4-02 Potential Receptor Surveys and Risk Evaluation Procedures at Petroleum Release Sites. Identify all vapor monitoring locations on the Vapor Survey Map by labeling each monitoring location with a number that corresponds to vapor monitoring locations listed in Table 19. Vapor monitoring methods, including instruments used, must be discussed in Section Provide a detailed description of each vapor monitoring location and indicate if vapors were detected. A vapor survey was not completed under this scope of work. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

42 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 40 Vapor Intrusion Receptors When vapor intrusion receptors are present, a preliminary vapor intrusion risk assessment must be completed (see Guidance Document 4-01a Vapor Intrusion Assessments Performed during Site Investigations). If completed, include the Vapor Intrusion Assessment Map in Section 4 that identifies all vapor intrusion samples and receptors at and within the 100-foot preliminary assessment area Was a preliminary vapor intrusion risk assessment completed? If NO, explain why. Yes No Petroleum vapor intrusion assessment was not requested by the MPCA under this scope of work. The Site is currently vacant with no inhabited receptors within 100 feet of the identified release areas Do any of the soil gas samples from locations near inhabited buildings exceed the ISVs by ten times (10X) for petroleum related compounds? If you answered YES, is additional characterization of the vapor intrusion pathway needed for these buildings (e.g. sub-slab soil gas, an indoor building survey, or indoor air sampling)? If YES, complete question 3.4. If NO, explain why Have sufficient data been collected to propose a Conceptual Corrective Action Design for buildings that are likely to be impacted by petroleum vapors? If YES, describe your justification for corrective action Based on the horizontal extent of impacted ground water or free product from the release, is additional soil gas sampling required beyond the 100-foot preliminary assessment area near inhabited buildings? If YES, describe your proposal for additional vapor intrusion sampling. If NO, explain why Were recommended field sampling procedures and laboratory QA/QC from Guidance Document 4-01a followed? If NO, explain why and discuss implications on data quality. Yes Yes Yes Yes Yes No NA No NA No NA No NA No NA Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

43 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 41 Site Conceptual Model Discussion 2.19 Provide a detailed site conceptual model (SCM). The SCM should integrate site-specific geology, hydrogeology, and the contaminant distribution with respect to identified exposure pathways (well receptors, surface water receptors, utilities and subsurface receptors, and vapor intrusion receptors). For additional information on SCM development, see Guidance Document 1-01 Petroleum Remediation Program General Policy. Localized areas of petroleum contaminated soil and groundwater were identified at the Site associated with historic Site usage as an industrial small arms manufacturing facility. A total of 22 USTs and 41 ASTs utilized for petroleum product storage were identified at the Site based on U.S. Army records dating back to Petroleum contamination was identified in the vicinity of former petroleum UST/AST areas as well as non-tank areas likely associated with historic industrial activities. Petroleum Contaminated Soil The extent and magnitude of petroleum contaminated soil identified at the Site appears limited based on the Site investigation activities completed to date. The petroleum soil contamination consists primarily of DRO and GRO compounds. No BTEX or MTBE compounds were identified in the soil samples collected during the LSI. The lack of extensive volatile petroleum compounds identified in the soil is likely indicative of the age of the releases and in some areas the type of petroleum product released. The deepest identified evidence of petroleum contamination based on soil analytical sampling was at a depth of 6 feet in soil boring SI The deepest identified evidence of petroleum contamination based on field evidence (petroleum odors) was to a depth of 12 feet in soil boring SI-4008-B7. Petroleum contaminated surface soil was identified in Section 4008 off of the southeast corner of Building 502. The risks associated with petroleum contaminated soil and surface soil appears low based on the current Site usage as vacant industrial. The sources of petroleum contamination (USTs/ASTs) have reportedly been removed according to U.S. Army records. Petroleum Contaminated Groundwater Groundwater investigation for petroleum contamination was limited for the LSI. Extensive groundwater investigation was completed for the TCAAP Site associated with chlorinated compounds. An active remediation system is operating at the Site along with ongoing groundwater monitoring to address chlorinated compound contamination in the resource aquifer. Groundwater sampling for the LSI was limited to Section 2002 (former housing area) and Section 1017 (petroleum ASTs). No evidence of petroleum contaminated groundwater was identified in Section 2002 based on the groundwater sampling conducted for the LSI. Petroleum groundwater contamination in Section 1017 was identified in the immediate vicinity of a former 300 gallon diesel AST (Tank 5) in soil boring SI-1017-B48A. Groundwater contamination above HRLs/HBVs/RAAs at this location consisted of HBV exceedances for GRO, DRO and naphthalene. The petroleum contaminated groundwater plume was generally defined by three additional temporary wells/soil borings in Section The risks associated with petroleum contaminated groundwater identified in Section 1017 appear low based on the extent and magnitude of the petroleum contamination and the lack of identified water supply well receptors within 500 feet of the identified release areas. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

44 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 42 Water Well Receptors The risks to water supply well receptors from Leak appear low based on the extent and magnitude of petroleum contamination identified. No water supply wells were identified within 500 feet of the identified release areas. An existing public supply non-community transient well (Unique number ) was identified directly down-gradient of the Site at the Big Ten Supper Club. This well is set in the Jordan Sandstone formation at a depth of 286 feet and is cased to a depth of 250 feet. Municipal supply wells identified in the area are located at least one mile from the Site and are set in the Prairie du Chien/Jordan or Mt. Simon/Hinckley resource aquifers. Supply wells identified at the Site were sealed. Surface Water Receptors Potential surface water receptors identified within 1/4 mile of the petroleum release areas include Rice Creek, an unnamed surface water feature in Section 3007 and Round Lake located south of the Site across Highway 96. The risk to these surface water features from Leak appears low based on the extent and magnitude of petroleum contamination identified and the location of these surface water features in relation to the identified release areas. Groundwater contamination was identified up-gradient of Rice Creek in Section 1017 near former Tank 5 (SI-1017-B48A). The extent of groundwater contamination in this area was generally defined by three additional temporary wells/soil borings (SI-1017-B65, SI-1017-B66 and SI-1017-B67). Utility Receptors Buried utility lines remain on the property. The risk to buried utility lines from Leak appears low based on a lack of inhabited receptors on the Site and the extent and magnitude of petroleum contamination identified. No visible or measurable free product was identified and no BTEX compounds were identified in the soil samples collected during the LSI. No vapor intrusion assessment or vapor survey work was completed during the LSI; however, the lack of extensive volatile petroleum compounds identified in the soil samples collected indicates that the potential for vapor migration along buried utility lines is limited. Vapor Intrusion Receptors There are currently no inhabited vapor intrusion receptors within 100 feet of the identified release areas at the Site. The current Site use is Vacant Industrial. The vapor intrusion risk associated with Leak appears low based on the magnitude and extent of petroleum contamination identified and the current Site use as a vacant industrial property. If the Site is redeveloped, a Development Response Action Plan (DRAP) should be prepared to address potential vapor intrusion issues based on the proposed Site usage Discuss any other Site concerns not included in the above discussion Site concerns are discussed in the previous section(s). Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

45 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 43 Section 3: Site Management Decision The site management decision should be based on the Program s objectives described in Guidance Document 1-01 Petroleum Remediation Program General Policy. 3.1 Recommendation for site: site closure additional ground water monitoring additional field-detectable vapor monitoring additional soil gas/vapor intrusion investigation corrective action 3.2 If closure is recommended, summarize significant investigative events and describe how sitespecific exposure pathways identified in question 2.19 have been adequately addressed. Site closure is recommended for Leak based on the Site investigation activities completed to date. The extent and magnitude of identified petroleum contamination is limited to localized release and/or spill areas associated with former petroleum storage tanks and the general industrial Site usage as a small arms ammunition manufacturing facility. Risks to specific exposure pathways are summarized below. The risks to water supply wells from petroleum contamination appear low based on a lack of supply wells identified within 500 feet of the release areas and no municipal supply wells identified within 1/2 mile of the release areas. The risks to down-gradient municipal supply wells from Leak in the City of New Brighton appear low based on the extent and magnitude of petroleum contamination identified and the well construction for these municipal wells. The groundwater from City of New Brighton supply wells is also treated for chlorinated compound contamination prior to distribution. The risks associated with vapor intrusion appear low based on the current Site use as a vacant industrial property and the lack of inhabited receptors within 100 feet of release areas. The risks associated with petroleum contaminated surface soil appear low based on the current Site usage as vacant industrial. The risks to surface water features appear low based on the extent and magnitude of soil and groundwater contamination identified and the locations of the identified petroleum contamination in relation to the surface water features. No visible or measurable free product was identified during the LSI. Significant Site investigation activities are summarized below. Leak number 3635 was associated with a UST removal in 1987 in Section The release was investigated and closed by MPCA in February Leak number 4852 was identified in November 1991 associated with a former tank farm area in Sections 1009 and Leak 4852 was closed by MPCA in December 1986 based on an excavation report and contaminated soil removal. Leak number 6996 was identified in October 1993 associated with a former tank farm area in Section A remedial investigation was completed and MPCA closed the Site in May A Phase I and Phase II Environmental Site Assessment for the 774-acre transfer property was completed by Plexus Scientific, report dated February The Phase I/II ESA included Site Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

46 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 44 investigation at 17 former UST and AST locations as well as former production areas not directly associated with storage tanks. A Supplemental Remedial Investigation (RI), Field Sampling Plan was prepared by Tetra Tech dated September The laboratory analytical data reports were not provided with the Tetra Tech Supplemental RI; therefore, the laboratory analytical data has not been reviewed or approved by the MPCA. The results of the Supplemental RI were only used as a reference for scoping potential additional investigation areas for the LSI. 3.3 If additional ground water or field-detectable vapor monitoring is recommended, indicate the proposed monitoring locations, sampling frequency, and target analytes. Conduct quarterly ground water monitoring and sampling until the MPCA responds to this report. No additional groundwater or field-detectable vapor monitoring is recommended for Leak based on the Site investigation activities completed to date and the current Site usage as a vacant industrial property. 3.4 If additional vapor intrusion investigation is recommended, provide details of proposed activities such as completing an indoor building survey, sub-slab vapor sampling, indoor air sampling, or locations for additional soil gas sampling. No additional vapor intrusion investigation is recommended for Leak based on the Site investigation activities completed to date and the current Site usage as a vacant industrial property. 3.5 If corrective action is recommended, provide a conceptual approach by completing Guidance Document 4-19 Conceptual Corrective Action Design Worksheet and include in Section 6. See Guidance Document 4-10 Elements of the Corrective Action Design for more information on the corrective action design process and other requirements. (Note: MPCA staff will review this report at a higher-than-normal priority to determine if corrective action is required.) Corrective action is not recommended for Leak based on the results of the Site investigation work completed to date and the current Site usage as a vacant industrial property. Corrective action may be required if the Site is redeveloped based on the redevelopment use. Site redevelopment activities should be conducted under a Development Response Action Plan (DRAP) to address any areas where remaining petroleum contaminated soil, soil vapor and groundwater is encountered in accordance with all MPCA rules and regulations and in accordance with the proposed Site usage. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

47 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 45 Section 4: Figures Attach the following figures in order of discussion in the text. All figures must include a north arrow, scale, and legend. Approximate scales are not acceptable. Figure 1 - Site Location Map, U.S. Geological Survey 7.5 minute quadrangle Figure 2 Aerial Photograph of Site Figure 3 Soil Boring and Surface Soil Assessment Location Diagram Figure 4 Soil Boring and Surface Soil Assessment Location Diagram Figure 4A Groundwater Analytical Results Figure 5 Soil Boring and Surface Soil Assessment Location Diagram Figure 6 Soil Boring and Surface Soil Assessment Location Diagram Figure 7 Soil Boring and Surface Soil Assessment Location Diagram Figure 8 Soil Boring and Surface Soil Assessment Location Diagram Figure 9 - Petroleum Storage Tank Location Diagram Figure 10A Cross Section Alignment Figure 10B Cross Section A-A Figure 10C Cross Section B-B Figure 10D Cross Section C-C Ground water gradient contour maps (for sites with monitoring wells) for each gauging event. Figure 11 Surface Water Receptor Diagram Figure 12 - Well Receptor Survey Diagram Vapor Survey Map showing utilities and buildings with basements and monitoring locations within 500 feet (if a survey was required). If the survey area has been expanded beyond 500 feet, adjust the map to encompass the entire surveyed area. Vapor Intrusion Assessment Map showing all vapor intrusion samples and receptors at and within the 100-foot preliminary assessment area. If the assessment area has been expanded beyond 100 feet, adjust the map to encompass the entire assessment area. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

48 TCAAP 585-Acre Transfer Property County Rd. I Lexington Avenue Highway ,000 2,000 q Highway 35W Highway 10 LEGEND Feet Approximate Property Boundary Source: Aerial Photograph from ArcGIS Resource Center Cheshire Ln N Suite 500 Minneapolis, MN T: F: Copyright 2010 By: AECOM SITE LOCATION DIAGRAM Twin Cities Army Ammunition Plan (TCAAP) 585-Acre Transfer Property Leak Arden Hills, Minnesota Drawn: Approved: Scale: PROJECT NUMBER FIGURE NUMBER TJG 10/27/11 RLD 10/27/11 1" = 2000'

49 LEAK #'S 2593, 13336, LEAK # 2803 LEAK # TCAAP 585-Acre Transfer Property CO. RD. I LEAK # 3635 LEAK # 4852 LEAK # 6996 Lexington Avenue LEAK # LEAK # LEAK #'s 3609 & 5753 Highway 96 LEAK # LEAK # 3188 qfeet 0 1,000 2,000 Highway 35 W Highway 10 LEGEND Approximate Property Boundary Source: Aerial Photograph from ArcGIS Resource Center Cheshire Ln N Suite 500 Minneapolis, MN T: F: Copyright 2010 By: AECOM AERIAL PHOTOGRAPH Twin Cities Army Ammunition Plan (TCAAP) 585-Acre Transfer Property Leak Arden Hills, Minnesota Drawn: Approved: Scale: PROJECT NUMBER FIGURE NUMBER TJG 10/27/11 RLD 10/27/11 1" = 2000'

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51 SI-1017-B48 6 ft. GRO 870 DRO 3750 SI-1010-B ft. GRO <5.3 DRO 16.3 SI-1010-B44 6 ft. GRO <5.7 DRO 11

52 SI-2003-B58(W) B <1 T <1 E <1 X <3 MTBE <1 GRO NA DRO <110 SI-2003-B64(W) B <1 T <1 E <1 X <3 MTBE <1 GRO NA DRO <110 SI-2003-B61(W) B <1 T <1 E <1 X <3 MTBE <1 GRO NA DRO <100 SI-1017-B48A SI-1017-B488 (Duplicate) B <1 <1 T <1 <1 E X MTBE <1 <1 GRO DRO SI-1017-B66 B <1 T <1 E <1 X <3 MTBE <1 GRO <100 DRO 140 SI-1017-B65 B <1 T <1 E <1 X <3 MTBE <1 GRO <100 DRO <100 SI-1017-B67 B <1 T <1 E <1 X <3 MTBE <1 GRO <100 DRO <100

53 SI-3008-B57 3 ft. GRO <5.8 DRO 81.1 SI-3008-B56 4 ft. GRO <5.4 DRO 33.3 SI-3008-B ft. GRO <6.6 DRO 23.3 SI-3008-B ft. GRO <5.6 DRO 63.1 SI-3002-B42 1 ft. GRO <5.8 DRO 176

54 SI-1012-B ft. GRO NS DRO 4440 SI-1008-B ft. GRO <5.6 DRO 16.4

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56 SI-4007-B9 4.5 ft. GRO 13.6 DRO 134 SI-4008-B7 4 ft. GRO 12.4 DRO <10.4 SI-4008-SS4 0-2 ft. GRO NS DRO 1,340 SI-4008-SS6 0-2 ft. GRO NS DRO 29.2 SI-4008-SS5 0-2 ft. GRO NS DRO 763 SI-4008-B3 2 ft. GRO <5.4 DRO 2,330

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62 Rice Creek TCAAP 585-Acre Transfer Property Unnamed Surface Water Feature q Round Lake LEGEND 0 1,000 2,000 Feet Approximate Property Boundary Source: Aerial Photograph from ArcGIS Resource Center Cheshire Ln N Suite 500 Minneapolis, MN T: F: Copyright 2010 By: AECOM SURFACE WATER RECEPTOR DIAGRAM Twin Cities Army Ammunition Plan (TCAAP) 585-Acre Transfer Property Leak Arden Hills, Minnesota Drawn: Approved: Scale: PROJECT NUMBER FIGURE NUMBER TJG 10/27/11 RLD 10/27/11 1" = 2000'

63 TCAAP 585-Acre Transfer Property # TCAAP 1 # TCAAP # TCAAP # # TCAAP 7 # TCAAP 8 # Big Ten Supper # TCAAP 9 # , Arden 0 1,000 2,000 q Feet LEGEND Source: Aerial Photograph from ArcGIS Resource Center Cheshire Ln N Suite 500 Minneapolis, MN T: F: Copyright 2010 By: WATER WELL RECEPTOR SURVEY Twin Cities Army Ammunition Plan (TCAAP) 585-Acre Transfer Property Leak Arden Hills, Minnesota Approximate Property Boundary Active Water Supply Well Location Abandoned Water Supply Well Location Drawn: Approved: Scale: PROJECT NUMBER FIGURE NUMBER TJG 10/27/11 RLD 10/27/11 1" = 2000'

64 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 46 Section 5: Tables Table Number and Name Table 1. Tank Information Table 2. Results of Soil Headspace Screening Table 3. Analytical Results of Soil Samples Table 4. Other Contaminants Detected in Soils (Petroleum or Non-petroleum Derived) Table 5. Contaminated Surface Soil Results Table 6. Water Level Measurements and Depths of Water Samples Collected from Borings Table 7. Analytical Results of Water Samples Collected from Borings Table 8. Other Contaminants Detected in Water Samples Collected from Borings (Petroleum or Non-petroleum Derived) Table 9. Monitoring Well Completion Information Table 10. Water Level Measurements in Wells Table 11. Analytical Results of Water Samples Collected from Wells Table 12. Other Contaminants Detected in Water Samples Collected from Wells (Petroleum or Non-petroleum Derived) Table 13. Natural Attenuation Parameters Table 14. Free Product Recovery Table 15. Properties Located within 500 feet of the Release Source Table 16. Water Supply Wells Located within 500 feet of the Release Source and Municipal or Industrial Wells within ½ mile Table 17. Surface Water Receptor Information Table 18. Utility Receptor Information Table 19. Vapor Survey Results Table 20. Results of Soil Gas Sampling for Vapor Intrusion Screening Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

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90 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 47 Section 6: Appendices Attach all required or applicable appendices in the following order. Indicate those appendices that are included in this report by marking the check box. All reproduced data must be legible. Reports missing required documentation are subject to rejection. Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Appendix H Appendix I Appendix J Appendix K Appendix L Appendix M Guidance Document 3-02 General Excavation Report Worksheet. Guidance Document 1-03a Spatial Data Reporting Form. Guidance Document 2-05 Release Information Worksheet. Copies of applicable Phase I and Phase II reports or supplemental sampling information such as aboveground storage tank (AST) upgrading and decommissioning sampling. Geologic Logs of Soil Borings, Including Construction Diagrams of Temporary Wells. Laboratory Analytical Reports for Soil and Ground Water. Methodologies and Procedures, Including Field Screening of Soil, Other Field Analyses, Soil Boring, Soil Sampling and Water Sampling. Sampling Information Forms for Groundwater Sampling of Temporary Monitoring Wells. Grain Size Analysis, Hydraulic Conductivity Measurements, and Other Calculations. Guidance Document 2-03 Free Product Recovery Report Worksheet. Copies of Water Supply Well Logs with Legible Unique Numbers. Results of the Public Water Supply Risk Assessment. If the Site is within a designated source water protection area, include a copy of the MDH Source Water Assessment and a map from the MPCA Petroleum Remediation Program Maps Online website. Guidance Document 4-19 Conceptual Corrective Action Design Worksheet. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

91 TCAAP 585-Acre Transfer Property, Leak AECOM Project Page 48 Web pages and phone numbers MPCA staff MPCA toll free Petroleum Remediation Program web page MPCA Info. Request MPCA VIC program MPCA Petroleum Brownfields Program MPCA SRS guidance documents MDH HRLs MDH DW hotline Petrofund Web Page &agency=Commerce Petrofund Phone or State Duty Officer or Upon request, this document can be made available in other formats, including Braille, large print and audio tape. TTY users call 651/ or Greater Minnesota (voice/tty). Printed on recycled paper containing at least 10 percent fibers from paper recycled by consumers. Guidance Document c-prp4-06: September 2008 Petroleum Remediation Program Minnesota Pollution Control Agency

92 AECOM LSI Report Environment TCAAP 585 Acre Transfer Property, Leak Appendix E Geologic Logs of Soil Borings APPENDIX DIVIDERS.DOCX November 2011

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