520 Lafayette Road 520 Lafayette Road St. Paul, Minnesota St. Paul, Minnesota

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1 February 4, 2015 Ms. Shanna Schmitt, Project Manager Ms. Amy Hadiaris, Technical Analyst Minnesota Pollution Control Agency Minnesota Pollution Control Agency VIC Program VIC Program 520 Lafayette Road 520 Lafayette Road St. Paul, Minnesota St. Paul, Minnesota Subject: Proposed Actions Letter and Request for No Association Determination Arden Hills, Minnesota MPCA Site ID: VP22892/PB4687 Bay West Project No. J Dear Ms. Schmitt and Ms. Hadiaris: Bay West LLC (Bay West) has prepared this letter to describe the proposed actions to be taken by Ramsey County (the County) in regards to mass grading, road construction, utility installation and other infrastructure improvements at the former Twin Cities Army Ammunition Plant (TCAAP) located at 2020 Highway Avenue, Arden Hills, Minnesota, in Ramsey County (the Site). The County is seeking the protection of a No Association Determination (NAD) under the Minnesota Environmental Response and Liability Act (MERLA) with respect to the identified releases of hazardous substances at the property. This NAD request is intended as a supplement to the Proposed Actions Letter/Request for No Association Determination submitted on behalf of Ramsey County by Wenck Associates, Inc. (Wenck) dated September 16, 2014 (September 16 PAL/NAD Request). As is noted in the September 16 PAL/NAD Request, the County seeks issuance of a No Association Determination for the proposed actions described below, as well as concurrence from the U.S. EPA and the Army with those proposed actions. BACKGROUND The Site consists of approximately 427 acres of the former TCAAP located in portions of Section 9 and 16, Township 30 North, Range 23 West. The County currently owns 397 of the 427 acres comprising the Site. The County has leased the remaining 30 acres of the Site from the United States (Leased Property). The Leased Property was known to contain areas of contamination in excess of the Minnesota Pollution Control Agency (MPCA) Tier II Soil Reference Values for industrial land use (Tier II SRVs). The County was to function as a response action contractor to complete the soil response action activities on the Leased Property on behalf of the United States Army (Army) to satisfy the Army s obligations under the

2 Proposed Actions Letter Federal Facilities Agreement. The County will take title to the Leased Property once the remediation is complete. The County entered into an agreement with Carl Bolander & Sons, Inc. (Bolander) to complete hazardous material abatement, demolition of Site improvements, and remediation of releases of hazardous substances and petroleum to the soil at the Site. The scope of remediation activities under Bolander s agreement with the County required remediation of all soil located above the unconfined water table aquifer with identified contamination exceeding MPCA Tier 1 SRVs for residential land use. Remediation work commenced at the Site in May 2013 and is scheduled to be complete by October Once the Site remediation is complete, the County will request that the MPCA issue a Commissioner s Certificate of Completion for soil, and request amendment of the Operable Unit 2 (OU2) Land Use Control Remedial Design (LUCRD) and associated environmental covenants to allow residential use throughout the Site. IDENTIFIED RELEASE The identified release at the Site includes all hazardous substances identified and described in the MPCA s file, including, without limitation, heavy metals (e.g., antimony, arsenic, barium, copper, chromium, manganese, mercury, lead, thallium and vanadium), polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and volatile organic compounds (VOCs). The Identified Release refers to contamination of all affected media at the Site including soil, groundwater, soil gas, and any other affected media. PROPOSED ACTIONS We request that the MPCA issue a NAD to the County with respect to the Identified Release for the following proposed actions: Excavation, grading, movement, and stockpiling of soil located above the unconfined water table aquifer as these activities relate to construction site preparation, road construction, mass grading, utility installation and other infrastructure improvements. A figure illustrating the proposed spine road alignment and associated sewer and water utilities is attached as Exhibit A. Excavation, movement, stockpiling, and appropriate disposal of soil located below the unconfined water table aquifer when these activities occur in areas of known groundwater contamination and are completed in accordance with an MPCA-approved Response Action Plan (RAP). These areas are depicted on Exhibit B from the September 16 PAL/NAD request and Exhibit C, the grading plan for Rice Creek. Excavation, grading, movement, and stockpiling of soil located below the unconfined water table aquifer when these activities occur in areas with no known groundwater contamination. Page 2

3 Proposed Actions Letter Construction of surface water management features, stormwater retention and infiltration basins, mitigated wetlands, and the new channel for Rice Creek in areas with no known contamination in the unconfined water table aquifer. These areas are depicted on Exhibit B from the September 16 PAL/NAD request and Exhibit C, the grading plan for Rice Creek. Construction of surface water management features, stormwater retention basins, mitigated wetlands, and the new channel for Rice Creek in areas with known contamination in the unconfined water table aquifer when these activities are completed in accordance with an MPCA-approved RAP. These areas are depicted on Exhibit B from the September 16 PAL/NAD request and Exhibit C, the grading plan for Rice Creek. Ramsey County will seek the concurrence of MPCA, Army, and USEPA prior to construction of stormwater management features in these areas to ensure they do not alter the groundwater flow regime in areas affected by historical solvent releases. Dewatering of excavation areas and discharge of water to an on-site infiltration basin when this work is completed in areas of the Site with no known contamination in the unconfined water table aquifer. Dewatering of excavation areas and discharge of water to the local POTW when this work is completed in areas of the Site with known or suspected contamination in the unconfined water table aquifer and is completed in compliance with a discharge permit. Sampling, excavation, segregation, stockpiling, and appropriate disposal of previously unidentified contaminated media in accordance with an MPCA-approved Construction Contingency Plan (CCP). All other actions of the County and its contractors and subcontractors associated with acquiring, maintaining, and preparing the Site for sale and redevelopment consistent with the Master Plan approved by the County and City of Arden Hills, including without limitation construction, installation and/or relocation of roads, utilities, sewers, water lines and other infrastructure. If you have any questions regarding this request, please contact either me or Donovan Hannu using the contact information provided below. Respectfully yours, Rick Van Allen, PG Donovan Hannu, PE Senior Project Manager Project Manager Page 3

4 Proposed Actions Letter Attachments Exhibit A - TCAAP Preliminary Spine Road and Utility Plan Exhibit B Figure 1 from the Wenck September 2014 PAL/NAD Exhibit C - Rice Creek channel excavation and meander cc: Heather Worthington, Ramsey County Beth Engum, Ramsey County Rick Kubler, Gray Plant Mooty Page 4

5 Exhibit A Department of Public Works ENGINEERING/OPERATIONS RAMSEY COUNTY 1425 Paul Kirkwold Drive Arden Hills, MN (651) (FAX) (651) SITE GRADING AND INFRASTRUCTURE IMPROVEMENTS JANUARY 2015

6 Exhibit B Legend Subject Property Areas Excluded from Stormwater Reintroduction Site K TCE, Building 102 (All VOC) Plumes Site K, associated with former Building 103 Building 102 Plume Site I, associated with former Building Aerial Photograph (Source: ESRI) Feet ± Path: L:\1382\0001\mxd\TASK 03 Stormwater Prelim Design\Site I and K Location.mxd Date: 9/16/2014 Time: 9:06:04 AM User: ShuJC0243 Source: Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community RAMSEY COUNTY TCAAP: 427-acre Redevelopment Infiltration Engineers - Scientists Business Professionals Wenck 1800 Pioneer Creek Center Maple Plain, MN AUG 2014 Figure 1

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