remedy feasibility assessment

Remedy Feasibility Assessment

Washington County Landfill Lake Elmo, Minnesota

Prepared for MPCA Closed Landfill Program

SEH No. A-MNPCA0802.00

Effective Date: November 15, 2007

Short Elliott Hendrickson Inc., 418 West Superior Street, Suite 200, Duluth, MN 55802-1512 SEH is an equal opportunity employer | www.sehinc.com | 218.279.3000 | 888.722.0547 | 218.279.3001 fax

November 15, 2007 RE: Remedy Feasibility Assessment Washington County Landfill MPCA Closed Landfill Program Lake Elmo, Minnesota SEH No. A-MNPCA0802.00

Mr. Shawn Ruotsinoja Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, MN 55155 Dear Mr. Ruotsinoja: Short Elliott Hendrickson Inc. (SEH®) is pleased to submit this Remedy Feasibility Assessment report to the Minnesota Pollution Control Agency (MPCA) pertaining to the closed Washington County Landfill located in Lake Elmo, Minnesota. This report has been prepared in general accordance with SEH’s October 5, 2007 Work Plan for Remedy Feasibility Assessment approved by MPCA under Contract No. A90801 (Work Order No. SEH-W40-08-01). SEH has been contracted to independently review the feasibility of the following six possible remedies provided to us by the MPCA related to the landfill contamination at the subject property: No Additional Action Plasma Torch Force Main (Groundwater extraction/off-site disposal) Pump and Treat (Groundwater extraction/treat/infiltrate on-site) Dig and Truck Dig and Line

SEH assessed the proposed remedies in accordance with the two threshold and five balancing criteria described in the United States Environmental Protection Agency (USEPA) publication EPA/540/P-91/001 Conducting Remedial Investigations/Feasibility Studies of CERCLA Municipal Landfill Sites (February 1991). At the direction of the MPCA, SEH did not evaluate the possible remedies against the USEPA’s two modifying criteria: Agency Acceptance and Public Acceptance. If you have any questions regarding the information contained herein, please contact me at 218.279.3022. Sincerely, Colin Reichhoff, PG Project Manager BKO/BLK/GCC/CRR/ls/MJB/CWI c: Ingrid Verhagen, MPCA

Peter Tiffany, MPCA p:\projects\uz\w\widnr\common\wash. co. remedy feasibility assessment\remedy feasibility assess.doc

Washington County Landfill Remedy Feasibility Assessment Date: 11/15/07

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Executive Summary Short Elliott Hendrickson Inc. (SEH®) has prepared this Remedy Feasibility Assessment (RFA) Report for the closed Washington County Landfill at the request of the Minnesota Pollution Control Agency (MPCA). The landfill is located within the city limits of Lake Elmo in Washington County, Minnesota. The original permitted area was 110 acres in size with a fill area of approximately 35 acres.

Perfluorochemicals (PFCs) have been identified in groundwater at levels above the Minnesota Department of Health (MDH) groundwater and toxicological limits known as Health Risk Limits (HRLs). In addition to PFCs, several volatile organic compounds (VOCs) have also been identified in the groundwater at concentrations exceeding their respective HRL. An existing spray irrigation system installed at the site has historically been successful in treating VOC impacted water recovered from the site groundwater extraction wells. However, the spray irrigation system is not providing effective treatment of the PFC constituents.

The RFA provides an independent feasibility review of the six potential remedies selected by the MPCA to address contamination presence and migration related primarily to PFC compounds associated with the site. The six potential remedial options that the MPCA requested SEH evaluate are:

No Additional Action Plasma Torch Force main (groundwater extraction with off-site disposal) Pump and Treat (groundwater extraction with treatment or infiltration on-site) Dig and Truck Dig and Line

Based on available site information, remedial technology evaluations by others, and SEH’s experience at similar municipal landfill sites, SEH has assessed the remedial action options against the following seven evaluation criteria:

Overall protection of human health and the environment Compliance with Applicable or Relevant and Appropriate Requirements Long-term effectiveness and performance Reduction of toxicity, mobility, or volume (TMV) through treatment Short-term effectiveness Implementability Cost

No Additional Action

The “No Additional Action” alternative is evaluated to provide a baseline for public health and welfare and environmental consequences of taking no further remedial action at the site. This alternative was initially labeled by MPCA as the “do nothing” alternative; however, since some remedial activities will continue at the site with this alternative, SEH changed the name to more accurately reflect the approach. It is understood that the existing remedial and monitoring effort would continue; however, further investigation and/or remediation with regards to PFC’s would cease.


Executive Summary (Continued)

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Plasma Torch

This alternative involves excavating the waste material from the landfill and converting the waste onsite to gas and inert slag material using plasma torch technology. Prior to excavating waste the groundwater recovery and infiltration system would be shut down and the private well GAC treatment system program would be expanded. It is assumed that the void created by the waste excavation would be graded to minimize excessive slopes and the landfill cover soils would be re-placed and seeded. The preliminary projection of initial capital and long-term annual costs for this option are approximately $192,300,000 and $87,000 per year, respectively.

Force Main

This remedial alternative involves pumping groundwater and discharging the untreated water to a force main, which would discharge to a waste water treatment facility (MCES). This option would require the construction of more than three miles of new force main from the landfill to the nearest City of Oakdale sanitary sewer. Assuming continuous operation of the groundwater recovery system, the cumulative discharge to the Oakdale sanitary system and MCES treatment plant would be approximately 60 million gallons per year. The preliminary projection of initial capital and long-term annual costs for this option are approximately $7,300,000 and $450,000 per year, respectively.

Pump and Treat On Site

Supplemental treatment is required to remove PFCs to below the applicable HRLs from the recovered groundwater. This option includes treatment of contaminated groundwater by air stripping and iron removal followed by granular activated carbon (GAC) to remove PFC compounds prior to discharge directly to the southeast infiltration basin. The preliminary projection of initial capital and long-term annual costs for this option are approximately $5,800,000 and $700,000 per year, respectively.

Dig and Truck

This alternative would involve excavating the waste from the landfill and transporting and disposing of the waste off site at a licensed solid waste facility. Prior to excavating waste it is assumed that the groundwater recovery and infiltration system would be shut down and the private well GAC treatment system program would be expanded. It is assumed that the void created by the waste excavation would be graded to minimize excessive slopes and the landfill cover soils would be re-placed and seeded. The preliminary projection of initial capital and long-term annual costs for this option are approximately $66,800,000 and $87,000 per year, respectively.

Dig and Line

The alternative would involve moving waste and constructing a lined landfill at the current site. Waste from the existing landfill would be excavated and placed on site while the excavated area of the landfill is lined. The waste would then be placed back in the lined location. Prior to excavating waste it is assumed that the groundwater recovery and infiltration system would be shut down and the private well GAC treatment system program would be expanded. The preliminary projection of initial capital and long-term annual costs for this option are approximately $27,600,000 and $210,000 per year, respectively.


Executive Summary (Continued)

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Comparison of Alternatives

SEH developed a ranking method to allow comparison of one alternative against another within each of the seven USEPA comparative criteria described above. The ranking method provided a balanced system to give equal weight to the seven criteria. The scoring was based upon each alternative’s relative rating when compared to the other alternatives. The relative ranking of the six remedial options follows (lowest score is considered the best):

Option Total Score No Additional Action 27 Plasma Torch 18 Force Main 20 Pump and Treat 16 Dig and Truck 15 Dig and Line 14

Dig and Line appears to be the most feasible remedial action option, followed closely by the Dig and Truck and Pump and Treat options. Additional evaluation of the modifying criteria (agency acceptance and public acceptance) may be required by MPCA prior to selection of a final remedy. Once a final remedy is selected, design studies should be conducted or refined to further define the cost, approach, permit requirements and schedule.


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Remedy Feasibility Assessment

Washington County Landfill Lake Elmo, Minnesota

Prepared for: MPCA Closed Landfill Program

Prepared by: Short Elliott Hendrickson Inc.

418 West Superior Street, Suite 200 Duluth, Minnesota 55802-1512


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I hereby certify that this document and attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information contained in this document. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information; the information contained in this document is, to the best of my knowledge and belief, true, accurate, and complete. Colin Reichhoff, PG Project Manager Cyrus Ingraham, PE Client Service Manager Brian Kent, CHMM Senior Scientist Gloria Chojnacki, CHMM Senior Scientist Bruce Olson, PE Senior Engineer Mark Broses, PE Senior Engineer


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List of Abbreviations/Terms ARAR Applicable or Relevant and Appropriate Requirement ATSDR Agency for Toxic Substances and Disease Registry Barr Barr Engineering Co. bgs below ground surface Btu British thermal unit CERCLA Comprehensive Environmental Response, Compensation and Liability Act CFR Code of Federal Regulations Cost Matrix Washington County Landfill Alternative Selection Matrix-Costs CRA Conestoga-Rovers & Associates CSM Conceptual Site Model GAC Granular Activated Carbon gpm gallons per minute HBV Health Based Value HRL Health Risk Limit LFG Landfill Gas LFGTE Landfill Gas to Energy MCES Metropolitan Council Environmental Services MCL Maximum Contaminant Level MDH Minnesota Department of Health MDNR Minnesota Department of Natural Resources mg/kg-day milligrams per kilogram per day mg/m3 milligrams per cubic meter MGS Minnesota Geological Survey Mn/DOT Minnesota Department of Transportation MPCA Minnesota Pollution Control Agency MSW Municipal Solid Waste MW Megawatt m.y. million years NFPA National Fire Protection Association NMOC Non-Methane Organic Compounds NPDES National Pollutant Discharge Elimination System OMM Operation, Maintenance, and Monitoring OSHA Occupational Safety and Health Administration PFC Perfluorochemical PFBA Perfluorobutanoic Acid PFBS Perfluorobutane Sulfonate PFHxA Perfluorohexanoic Acid PFHxS Perfluorohexane Sulfonate PFOA Perfluorooctanoic Acid PFOS Perfluorooctane Sulfonate PFPeA Perfluoropentanoic Acid ppb parts per billion PVC Polyvinyl Chloride RAL Recommended Allowable Limit RAP Response Action Plan RCL Residual Contaminant Level RFA Remedy Feasibility Assessment RfC Reference Concentration RfD Reference Dose SAC Sewer Access Charge


List of Abbreviations/Terms (Continued)

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SEH Short Elliott Hendrickson Inc. site Washington County Landfill SLV Soil Leaching Value SRV Soil Reference Value subject property Washington County Landfill TBC To Be Considered TLV Threshold Limit Value TMV Toxicity, Mobility or Volume μg/L micrograms per liter URS URS Corporation USEPA United States Environmental Protection Agency VC Vinyl Chloride VOC Volatile Organic Compound

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SEH is a registered trademark of Short Elliott Hendrickson Inc. A-MNPCA0802.00

Table of Contents Letter of Transmittal Executive Summary Title Page Certification Page List of Abbreviations/Terms Table of Contents

Page

1.0 Introduction............................................................................................................ 1-1 1.1 Project Contacts.............................................................................................. 1-2 1.2 Report Format and Organization .................................................................... 1-3 1.3 Site Description............................................................................................... 1-3 1.4 History of Contamination................................................................................. 1-3 1.5 Site Geology ................................................................................................... 1-4 1.6 Current Remedial Actions ............................................................................... 1-5

1.6.1 Landfill Cover System ......................................................................... 1-6 1.6.2 Leachate Management........................................................................ 1-6 1.6.3 Landfill Gas Extraction System ........................................................... 1-6 1.6.4 Gradient Control System (Groundwater Extraction and Treatment) ... 1-7 1.6.5 Groundwater Monitoring System......................................................... 1-7

1.7 Contaminants of Concern ............................................................................... 1-8 1.7.1 PFCs ................................................................................................... 1-8 1.7.2 Benzene .............................................................................................. 1-9 1.7.3 Vinyl Chloride ...................................................................................... 1-9

2.0 Applicable Regulations ......................................................................................... 2-1 2.1 Chemical-Specific Requirements.................................................................... 2-1 2.2 Location-Specific Requirements ..................................................................... 2-1 2.3 Action-Specific Requirements......................................................................... 2-2

3.0 Remedial Action Alternatives ............................................................................... 3-1 3.1 Primary Remedial Action Alternative Development Assumptions................... 3-1 3.2 Evaluation Criteria........................................................................................... 3-1

3.2.1 Overall Protection of Human Health and the Environment.................. 3-2 3.2.2 Compliance with ARARs ..................................................................... 3-2 3.2.3 Long-Term Effectiveness and Permanence........................................ 3-2 3.2.4 Reduction of Toxicity, Mobility, or Volume (TMV) Through

Treatment ............................................................................................ 3-2 3.2.5 Short-Term Effectiveness.................................................................... 3-2 3.2.6 Implementability .................................................................................. 3-3 3.2.7 Cost ..................................................................................................... 3-3

3.3 Detailed Evaluation of Remedial Alternatives ................................................. 3-3 3.3.1 Remedial Alternative: No Additional Action......................................... 3-3

3.3.1.1 Overall Protection of Human Health and the Environment . 3-4

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3.3.1.2 Compliance with ARARs..................................................... 3-5 3.3.1.3 Long-Term Effectiveness and Permanence........................ 3-5 3.3.1.4 Reduction in Toxicity, Mobility, or Volume .......................... 3-5 3.3.1.5 Short-Term Effectiveness ................................................... 3-5 3.3.1.6 Implementability .................................................................. 3-6 3.3.1.7 Costs................................................................................... 3-6

3.3.2 Remedial Alternative: Plasma Torch ................................................... 3-6 3.3.2.1 Overall Protection of Human Health and the Environment . 3-9 3.3.2.2 Compliance with ARARs..................................................... 3-9 3.3.2.3 Long-Term Effectiveness and Permanence...................... 3-10 3.3.2.4 Reduction in Toxicity, Mobility, or Volume ........................ 3-10 3.3.2.5 Short-Term Effectiveness ................................................. 3-10 3.3.2.6 Implementability ................................................................ 3-10 3.3.2.7 Costs................................................................................. 3-10

3.3.3 Remedial Alternative: Force Main ..................................................... 3-11 3.3.3.1 Overall Protection of Human Health and the

Environment...................................................................... 3-13 3.3.3.2 Compliance with ARARs................................................... 3-14 3.3.3.3 Long-Term Effectiveness and Permanence...................... 3-14 3.3.3.4 Reduction in Toxicity, Mobility, or Volume ........................ 3-14 3.3.3.5 Short-Term Effectiveness ................................................. 3-14 3.3.3.6 Implementability ................................................................ 3-15 3.3.3.7 Costs................................................................................. 3-15

3.3.4 Remedial Alternative: Pump and Treat ............................................. 3-15 3.3.4.1 Overall Protection of Human Health and the


3.3.5 Remedial Alternative: Dig and Truck................................................. 3-20 3.3.5.1 Overall Protection of Human Health and the


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Table of Contents (Continued)

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3.3.6 Remedial Alternative: Dig and Line................................................... 3-24 3.3.6.1 Overall Protection of Human Health and the


4.0 Comparison of Alternatives.................................................................................. 4-1 4.1 Overall Protection of Human Health and the Environment ............................. 4-1 4.2 Compliance with ARARs................................................................................. 4-2 4.3 Long-Term Effectiveness and Permanence.................................................... 4-2 4.4 Reduction of Toxicity, Mobility, or Volume ...................................................... 4-3 4.5 Short-Term Effectiveness ............................................................................... 4-3 4.6 Implementability .............................................................................................. 4-3 4.7 Cost................................................................................................................. 4-4

5.0 Remedy Feasibility Assessment Summary......................................................... 5-1 6.0 Standard of Care.................................................................................................... 6-1 7.0 References and Resources................................................................................... 7-1

List of Tables Table 1 Summary of Criteria Evaluation Table 2 Comparison of Remedial Action Alternatives

List of Figures Figure 1 Pictorial CSM Figure 2 Fate and Transport Flow CSM Figure 3 Site Location Map Figure 4 Bedrock Geology

List of Appendices Appendix A Remedy Ranking Criteria Appendix B Preliminary Engineers Cost Projections Appendix C MPCA Cost Matrix Appendix D URS Information Appendix E CRA Information

Section 1 – Introduction

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1.0 Introduction Short Elliott Hendrickson Inc. (SEH®) has prepared this Remedy Feasibility Assessment (RFA) for the closed Washington County Landfill (site or subject property) located in Lake Elmo, Minnesota. This RFA has been prepared at the request of the Minnesota Pollution Control Agency (MPCA) Closed Landfill Program. SEH has been retained by the MPCA to independently review the feasibility of the six potential remedies selected by the MPCA to address contamination presence and migration related primarily to perfluorochemical (PFC) compounds associated with the site. PFCs have been identified in groundwater at levels above the Minnesota Department of Health (MDH) groundwater and toxicologic limits known as Health Risk Limits (HRLs). In addition to PFCs, several volatile organic compounds (VOCs) have also been identified in the groundwater at concentrations exceeding their respective HRL.

The six potential remedial options that the MPCA requested SEH evaluate are:

No Additional Action Plasma Torch Force main (groundwater extraction with off-site disposal) Pump and Treat (groundwater extraction with treatment or infiltration

on-site) Dig and Truck Dig and Line

The option above titled “No Additional Action” was initially presented to SEH as “Do Nothing.” Because this option involves the continued operation of the current remedial action, this remedial alternative is being renamed as “No Additional Action” to more accurately reflect the approach.

The scope of the RFA is to evaluate the above remedial actions in accordance with the two threshold and five balancing criteria described in the United States Environmental Protection Agency (USEPA) publication EPA/540/P-91/001 Conducting Remedial Investigations/Feasibility Studies of CERCLA Municipal Landfill Sites (USEPA, 1991a). The two threshold criteria are: Overall Protection of Human Health and the Environment Compliance with Applicable or Relevant and Appropriate Requirements

(ARARs)

The five balancing criteria are: Long-Term Effectiveness and Permanence Reduction of Toxicity, Mobility, or Volume (TMV) Through Treatment Short-Term Effectiveness Implementability Cost


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As directed by the MPCA, SEH has not evaluated the remedial options against the USEPA’s modifying criteria: Agency Acceptance and Public Acceptance. The remedy ranking method developed by SEH allows comparison of one alternative against another with respect to the seven criteria listed above. Scoring is based upon each alternative’s relative rating when compared to the other alternatives. The remedy ranking method is described in a letter to the MPCA dated October 26, 2007. The method description is included in Appendix A, “Remedy Ranking Criteria.” A Conceptual Site Model (CSM) has been developed for the site to assist in the evaluation of the potential alternatives with regard to elimination of risk due to exposure to contaminant releases from the site. A CSM is a basic schematic of how contaminants enter and contaminate the various media of concern, the mechanisms of contaminant transport, and potential routes of exposure for various populations. It provides a framework for assessing risks, developing remedial strategies, identifying source control requirements, and addressing unacceptable risk. The CSM is a tool to support contaminant management and remediation issues. A pictorial schematic of a typical landfill CSM by the USEPA is included as Figure 1, “Pictorial CSM.” A fate and transport flow diagram of the CSM is presented on Figure 2, “Fate and Transport Flow CSM.”

1.1 Project Contacts

1. Shawn Ruotsinoja Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, MN 55155 651.282.2382

2. Ingrid Verhagen Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, MN 55155 651.296.7266

3. Peter Tiffany Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, MN 55155 651.296.7274

5. Colin Reichhoff, PG, Project Manager Short Elliott Hendrickson Inc. 418 West Superior Street, Suite 200 Duluth, MN 55802-1512 218.279.3022


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1.2 Report Format and Organization The introduction briefly summarizes the existing conditions at the landfill, identifies the contaminants of concern, and provides a brief description of the contaminants.

The remainder of this report summarizes the Remedy Feasibility Assessment and includes the following sections:

Section 2, Applicable Regulations – Summarizes potential applicable or relevant and appropriate requirements

Section 3, Remedial Action Alternatives – Presents a detailed evaluation of remedial action alternatives selected by the MPCA

Section 4, Comparison of Alternatives – Compares remedial action alternatives

Section 5, Remedy Feasibility Assessment Summary Section 6, Standard of Care Section 7, References and Resources

1.3 Site Description

The Washington County Landfill is located within the city limits of Lake Elmo in Washington County, Minnesota. The original permitted area was 110 acres in size with a fill area of approximately 35 acres. The site is further described as being in the south 40 acres of Government Lot 5 of Section 10, 40 acres within the SE ¼ of the SW ¼ of Section 10, and the north 30 acres within the N ½ of the NW ¼ of Section 15, T29N, R21W (MPCA, 2007). The site, approximately nine miles northeast of downtown St. Paul, is depicted on Figure 3, “Site Location Map.”

Land use near the site is primarily residential and recreational. Lake Jane Hills State Park and Sunfish Lake Park are located north and east of the site, respectively. Lake Jane is located approximately ½ mile north of the site. A City of Lake Elmo fire station is located immediately north of the site. The site does not lie within a flood plain and there are no wetlands on the site. Surface water ponding at the site is the result of irregular settlement of the landfill cover and inadequate drainage.

1.4 History of Contamination Prior to its use as a sanitary landfill, the site was mined for sand and gravel. Washington County originally purchased the site in 1968 and designated 40 acres as a sanitary landfill disposal area. The landfill was permitted in 1969 as publicly owned and operated by Washington and Ramsey counties. The landfill accepted mixed municipal and industrial waste from 1969 to 1975. Approximately 2,570,000 cubic yards of waste (excluding cover material) has been placed to an average depth of 30 feet (1.95 million cubic meters). The solid waste is estimated to be comprised of 73 percent residential wastes, 26 percent commercial/industrial waste and 1 percent demolition waste (MPCA, 2007; USEPA, 2004).


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In 1983, nearby private drinking wells to the southwest were found to have concentrations of VOCs near or exceeding the drinking water standards established by the MDH. A remedial action, consisting of the installation and operation of a groundwater gradient control and spray irrigation system, was implemented in 1983 to mitigate groundwater contaminated with VOCs. In 1993, a barrier gas extraction system was installed to mitigate landfill gas migration to the west. Ownership and responsibility for the site was transferred to the MPCA through the Closed Landfill Program in 1996 (MPCA, 2007).

In 2004, the MPCA detected perfluorooctanoic acid (PFOA) in the groundwater of residential wells at concentrations in excess of the MDH Health Based Value (HBV). This resulted in a rescoring and reclassifying of the site in 2005 by the MPCA within the Closed Landfill Program. The MDH laboratories expanded its PFC methods in 2006 to include a greater number of PFCs. As a result, in addition to PFOA, detections of perfluorooctane sulfonate (PFOS) and perfluorobutanoic acid (PFBA) were found in excess of MDH well advisory guidelines within residential wells (MPCA, 2007).

1.5 Site Geology The surficial geology in the vicinity of the Washington County Landfill consists of unconsolidated Pleistocene-aged glacial and fluvial sediments which are associated with the Late Wisconsinan advance of the Superior Lobe. The unconsolidated sediments at the site consist of near surface deposits of silty clay and till associated with the St. Croix Moraine; these fine-grained sediments overlie coarser sand and gravel deposits which likely represent glacio-fluvial outwash deposits. The unconsolidated sediments typically range from 50 feet 150 feet thick and rest un-conformably on Palezoic sedimentary rocks.

The upper bedrock surface has been deeply eroded, the time-span represented by this erosional surface (between the deposition of the bedrock and the overlying glacial deposits) exceeds 500 million years (m.y.). This bedrock surface in places has been incised by bedrock valleys which have been infilled by glacial sediments up to 300 feet thick. A shallow, north-south trending bedrock valley has been identified beneath the Washington County Landfill.

The bedrock underlying the unconsolidated sediments at the site in the center of the bedrock valley is the Ordovian-aged Prairie du Chien Group rocks (505 to 478 m.y.) consisting primarily of dolomitic carbonates with interbedded layers of sandstone and chert. A map (Barr, 2005) depicting the bedrock geology of the Washington County Landfill area is shown in Figure 4, “Bedrock Geology.”

To the west and east of the bedrock valley the upper bedrock unit present is the Upper Ordovician St. Peter Sandstone (approximately 458 m.y.) which consists primarily of fine to medium grained quartz sandstones with interbedded layers of mudstone, siltstone and shale near its base; these fine grained units typically serve as a confining unit restricting the downward flow of water into the rocks of the Prairie du Chien group.


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Underlying the Prairie du Chien Group is the Upper Cambrian-aged Jordan Sandstone (approximately 500 m.y.); in the Twin Cites area this unit is dominated by the Van Oser Member which consists primarily of medium to coarse grained quartz sandstones (Austin, 1972).

In 2007, the Minnesota Geological Survey (MGS) issued a report documenting the findings of a geophysical logging project conducted on 185 residential wells in the area impacted by PFC contamination. This investigation was intended to provide information concerning the subsurface conditions affecting the flow of groundwater in this area. The findings of this investigation indicate that over 95% of the wells studied were pumping water from the lower part of the St. Peter Sandstone aquifer and the remaining wells pumped water from the unconsolidated glacial deposits.

The MGS investigation documented sedimentary beds (fine-grained sandstones and siltstones) occurring in the lower portion of the St. Peter aquifer that could limit the vertical flow of groundwater; however, the effectiveness of these units in restricting flow is greatly reduced in some areas due to secondary features, such as fractures and uncased water supply wells. In addition, similar secondary features were identified in the upper portion of the rocks that comprise the Prairie du Chien aquifer. This report documents the complexly inter-connected nature of the unconsolidated glacial deposits and the bedrock aquifers. These secondary features exist in both large and small scale and result in complex groundwater flow allowing groundwater to move preferentially and rapidly along these pathways (MGS, 2007).

Contamination from the landfill has been identified in all but the Jordan aquifer but is found primarily in the unconsolidated sediments and the Prairie du Chien Group (Barr, 2005).

Groundwater pumping rates and volumes predicted necessary to provide capture of contaminants originating from the landfill are based from multiple hydraulic modeling efforts, but did not appear to include the information provided in the MGS 2007 report discussed above. The model results reviewed by SEH indicate that these models originated from the Metro Model, which is a regional scale model representing the seven county Metro area. It appears that limited site specific data was used in developing the Washington County Landfill model, especially for the aquifers beneath the surficial aquifer. In light of the results of the recent geophysical logging project completed by MGS, further refinement of the model may be warranted, especially if hydraulic control is selected to be a component of the selected remedy for the site.

1.6 Current Remedial Actions The remediation system currently operating at the Washington County Landfill was developed in a Response Action Plan (RAP) approved by the MPCA on October 24, 1984. The purposes of the RAP were:

To capture groundwater impacted by VOCs in the unconsolidated deposits which were migrating off site and to prevent further release of impacted groundwater beyond the landfill limits. The contaminants of concern included acetone, benzene, chloroform, chloromethane,


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cis-1,2-dichloroethene, 1,1-dichloroethane, 1,1-dichloroethylene, dichlorofluoromethane, methylene chloride, trichlorofluoromethane, trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, and xylene

To treat the contaminated groundwater collected on-site through the use of a spray irrigation air-stripping system

To monitor the groundwater quality to evaluate the effectiveness of the remediation system and protect wells used by human receptors down gradient

To provide safe drinking water to residents that may be affected

The systems in place to limit and control groundwater impacts consist of a landfill cover, landfill gas extraction wells, and a series of groundwater extraction wells combined with an onsite treatment system.

1.6.1 Landfill Cover System The Washington County Landfill was capped following closure in 1975 with a two foot thick soil cover. The original soil cover was replaced and upgraded in 1996 to meet applicable standards and consists of a synthetic geomembrane, a drainage layer, 18 inch soil layer providing a vegetative rooting zone, and six inches of top soil. The cover system was intended to limit the amount of infiltration through the waste thereby minimizing the volume of contaminants carried to groundwater. This cover system has undergone differential settling since its installation resulting in the formation of surface depressions that allow ponding of surface water. This settlement can cause premature failure of the synthetic cover system and result in a pathway for infiltration of surface water. This cover system is scheduled for replacement in the next five years by the MPCA.

1.6.2 Leachate Management There is no landfill liner system in place and therefore no system is in place to capture and contain leachate at the site.

1.6.3 Landfill Gas Extraction System The original gas extraction system was designed as a perimeter barrier system intended to prevent the migration of potentially explosive landfill gas off site. This system was replaced in 1996 by a series of 14 gas extraction wells installed in the waste. These gas wells were connected to a blower system which imposed a negative pressure at the wells resulting in capture of the gas. Collected landfill gas is piped to a flare where it is destroyed. The MPCA estimates that 971,000 pounds of methane were destroyed by the flare system during 2006.

The primary purpose of the gas extraction system was to prevent migration of landfill gas (LFG). A likely secondary benefit is the removal of VOCs which can migrate with the gas and may result in groundwater impact some distance from the original contamination source. In 2006, the MPCA calculated that 0.1 pounds of non-methane organic compounds (NMOC) were removed by the collection and treatment of condensate removed from the landfill gas. Based upon the 2006 Annual Report, the gas extraction system has been effective in controlling landfill gas at the site.


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1.6.4 Gradient Control System (Groundwater Extraction and Treatment) The groundwater gradient control system implemented in compliance with the Response Action Plan was designed and installed in 1982 and 1983, and became operational on December 12, 1983. This system began as a single pumping well located near the southwest corner of the site and had a design capacity of 200 gallons per minute (gpm). Water from the system was piped to a spray irrigation system covering approximately 1.9 acres of sandy soils situated at the southeast corner of the site. Water passing through the spray irrigation system becomes aerated and promotes the volatilization of the VOCs dissolved in the groundwater. This system was modified following periodic monitoring and evaluation beginning in 1984, and eventually was expanded to include four groundwater extraction wells with a capacity of 400 gpm. To handle the increased discharge, modifications were made to the discharge area and in 1989 an National Pollutant Discharge Elimination System (NPDES) permit was issued allowing water from one of the wells to discharge to Eagle Point Lake located approximately two miles south of the site.

These four wells continued to operate until 2001 when it was determined that the system could be scaled back with well GC-1 providing contaminant capture. Since 2001, the MPCA has continued to optimize the gradient control system, the optimization includes the installation of an additional gradient control well (GC-5). As of 2006, there were three gradient control wells in use at the site which pumped approximately 57 million gallons of groundwater through the spray irrigation treatment system with discharge restricted to the site. The gradient control system had been considered to be operating effectively until PFCs were detected in monitoring wells at the site at concentrations exceeding the MDH groundwater standards. Evaluation of these chemicals suggest that while the gradient control/treatment system may be able to control the migration of VOCs, the PFCs cannot be effectively treated by air-stripping methods and further treatment will be required to remove these contaminants from the groundwater prior to discharge.

1.6.5 Groundwater Monitoring System. The groundwater monitoring system consists of 43 monitoring wells situated around the site. Groundwater samples are collected from these wells during the Spring, Summer and Fall of each year and the results of the subsequent analyses are evaluated to assess the effectiveness of the remediation system. Following the identification of PFCs as a contaminant of concern at this facility, nearby residential wells were sampled and analyzed to evaluate the potential impact. Over 500 samples were collected and analyzed from 404 locations. As a result of these analyses, municipal water lines have been extended to previously unserved areas and granulated activated carbon (GAC) treatment systems or bottled water has been provided to nearby residents. Currently there are 52 GAC systems in operation, and three residences currently on bottled water may receive a GAC unit in the future.


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1.7 Contaminants of Concern Hazardous substances have been released into soils, groundwater and the ambient air at the site. Based on information contained in the Third Five-Year Review Report (USEPA, 2004), the basis for taking action at the site was detection of VOCs in the soils and groundwater. Parameters in excess of ARARs included arsenic, manganese, benzene, and vinyl chloride. Since the USEPA review, several PFCs have been detected.

In 2007, the Minnesota Legislature established HRLs for PFOS and PFOA at 0.3 µg/L and 0.5 µg/L, respectively (MDH HRL, 10/24/2007). A drinking water well advisory guideline issued by the MDH has established 1 µg/L as a safe concentration for PFBA, perfluoropentanoic acid (PFPeA), and perfluorohexanoic acid (PFHxA). A well advisory guideline of 0.6 µg/L has been issued for perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS) (MDH, 2007a.).

Groundwater concentrations of PFOS have exceeded the HRL at on-site monitoring wells and the concentration of PFOA has exceeded the HRL in groundwater samples collected from both on-site wells and several private wells. PFBA has been detected at concentrations exceeding the drinking water guideline in samples collected from several private wells also. The remaining PFCs are monitored, but have not been detected at concentrations above their respective well advisory guidelines (MPCA, 2007).

The following HRLs have been developed for chemical concentrations found to be in excess of ARARs in the USEPA report: 5 µg/L has been established for benzene; 100 µg/L for manganese; and 0.2 µg/L for vinyl chloride. A HRL has not been issued for arsenic. However, the National Primary Drinking Water Regulations, set by the USEPA through the Safe Drinking Water Act, has established a maximum contaminant level (MCL) of 10 µg/L for arsenic.

Based on information in the Washington County Landfill – 2006 Annual Report (MPCA, 2007), benzene and vinyl chloride concentrations in the groundwater exceeded their respective HRLs at on-site wells; however, they do not appear to be impacting residential wells with the present gradient control system. Arsenic no longer appears to be exceeding the MCL. Manganese groundwater concentrations exceed the established HRL, but the MDH no longer recommends the HRL value (MDH HRL, 10/24/07).

1.7.1 PFCs PFCs are a family of manmade chemicals manufactured for use in household products such as: nonstick cookware, stain repellants, lubricants, pesticides, fire retardants and suppressants and other industrial applications. The chemicals are resistant to heat, oil, stains, grease, and water.

This family of chemicals is very stable and extremely resistant to breakdown in the environment. PFCs may enter the groundwater and travel long distances. PFCs are not easily evaporated into the air from water. They are also not easily absorbed through skin. PFC concentrations in water that are considered protective of human health have been established in the HRLs and drinking water guidelines established by the MDH and Minnesota Legislature as discussed above.


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Based on laboratory studies in animals, high concentrations of PFCs cause harmful changes in the liver, thyroid, immune system, blood, and other organs. Delays in maturation and growth have also been observed in animal studies. PFOA and PFOS in high concentrations have been shown to cause cancer in laboratory animals (MDH, 2007a).

“Reference dose” (RfD) is the daily dose that is unlikely to cause health effects of either a short or very long period of time. This represents a safe daily intake dosage of a chemical. A RfD of 0.00014 mg/kg-day for PFOA and 0.000075 mg/kg-day for PFOS was calculated by MDH (MDH, 2007b).

1.7.2 Benzene Benzene is a clear volatile, highly flammable liquid with a sweet odor. Benzene is formed from both natural processes and human activities. Benzene is used as a constituent in motor fuels, as a solvent for fats, inks, oils, paints, plastics, and rubber, in the extraction of oils from seeds and nuts, and in photogravure printing. It is also a chemical intermediate. Benzene is also used in the manufacture of detergents, explosives, pharmaceuticals, and dyes (Sittig, 1991).

Benzene evaporates into the air very quickly and dissolves slightly in water. Breathing benzene can cause headaches, drowsiness, dizziness, rapid heart rate, confusion, and unconsciousness. Eating or drinking high levels of benzene can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, and death. Long-term benzene exposure causes effects on the bone marrow and can cause anemia and leukemia. It can also cause excessive bleeding and affect the immune system (ATSDR, 2007).

Routes of entry into the body are inhalation of vapor, ingestion and eye contact. Benzene may gain entry into the body to some extent through percutaneous absorption through the skin, although benzene is poorly absorbed through intact skin.

The USEPA and MDH have set the maximum concentration of benzene in drinking water at 5 µg/L. The USEPA has established a chronic oral RfD for benzene at 0.004 mg/kg-day. The reference concentration for chronic inhalation exposure (RfC) for benzene is 0.03 mg/m3. Benzene is characterized as a known human carcinogen from animal studies with an oral slope factor ranging from 0.015 to 0.055 per mg/kg-day, the drinking water unit risk ranges from 4.4 x 10-7 to 1.6 x 10-6 per µg/L (USEPA IRIS, 2007a).

1.7.3 Vinyl Chloride Vinyl chloride is a colorless gas that burns readily and is unstable at room temperature. It has a mild sweet odor and does not occur naturally. It can be formed when other substances such as trichloroethane, trichloroethylene, and tetrachloroethylene are broken down. Vinyl chloride is used as a vinyl monomer in the manufacture of polyvinyl chloride (PVC) and other resins. PVC is used to make a variety of plastic products including pipes, wire and cable coatings, and packaging materials (Sittig, 1991; ATSDR, 2006).

Liquid vinyl chloride evaporates readily. Small amounts of vinyl chloride can dissolve in water. It also evaporates rapidly if near the surface in water or soil. Vinyl chloride in the air breaks down in a few days.


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Breathing high levels of vinyl chloride can cause dizziness of sleepiness. It can also cause you to pass out and can cause death. Long-term exposure over years can cause changes in the liver, nerve damage, and immune reactions. Skin contact with liquid vinyl chloride will cause numbness, redness, and blisters. Animal studies have shown that long-term exposure to vinyl chloride can damage the sperm and testes. Vinyl chloride has been characterized as a known carcinogen by the inhalation route of exposure and a likely carcinogen by the dermal route because it is readily absorbed and acts systemically. The target organ for vinyl chloride is the liver (ATSDR, 2006).

The MDH has set the maximum concentration of vinyl chloride in drinking water at 0.2 µg/L. The USEPA has established a chronic oral RfD for vinyl chloride at 0.003 mg/kg-day. The reference concentration for chronic inhalation exposure (RfC) for vinyl chloride is 0.1 mg/m3. The carcinogenic oral slope factor ranges from 0.72 per mg/kg-day for continuous lifetime exposure during adulthood to 1.5 per mg/kg-day for continuous lifetime exposure from birth. The drinking water unit risk ranges from 2.1 x 10-5 per µg/L for continuous lifetime exposure during adulthood to 4.2 x 10-5 per µg/L for continuous lifetime exposure from birth (USEPA IRIS, 2007b).

Section 2 – Applicable Regulations


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2.0 Applicable Regulations A brief summary of ARARs that may apply to remediation activities at the site are included in this section. The summary includes descriptions of chemical-specific, location-specific, and action-specific requirements for the selected remediation options. Numerous ARARs have been identified in previous documents. The potential ARARs discussed below include those previously identified as well as others SEH has identified that may apply.

2.1 Chemical-Specific Requirements Chemical-specific ARARs are requirements that regulate the release or presence of specific chemical constituents in the environment. These requirements generally establish risk-based concentrations or discharge limits for specific chemicals. The concentrations generally are determined based on human health risks.

For example, in Minnesota, target cleanup levels for specific chemicals in groundwater are established by the MDH as Health Risk Limits (HRLs) for Groundwater. The HRLs are established in Minnesota Rules Parts 4717.7100 to 4717.7800. Soil criteria are evaluated on a risk basis using Tier I and Tier II Soil Reference Values (SRVs) and Soil Leaching Values (SLVs) established by the MPCA.

Chemical specific cleanup levels may also be required for remediation residuals, including off-gases and water. Off-gases will be required to meet air emissions requirements listed in the Minnesota State Air Rules, Chapter 7001 through Chapter 7030. Federal Clean Air Act regulations may also apply to air emissions from remediation activities at the site.

Additional chemical-specific ARARs include, but are not limited to, the following:

MDH HRLs particularly related to PFOA and PFOS MN Statute 116.061 – Air Pollution Emission and Abatement 40 CFR Parts 141-143. National Primary and Secondary Drinking Water

Standards MPCA Guidance Document 4-15 Air Emission Controls for Soil Venting

Systems and Air Strippers

2.2 Location-Specific Requirements Location-specific ARARs are requirements that relate to the geographic location or features of the site. These requirements may affect the remedial action choices or may impose constraints on specific remedial alternatives.

The site is located in the vicinity of residential neighborhoods. Local ordinances may dictate maximum working noise levels, hours of operation, and traffic patterns. Local building, grading or mining permits may be required for excavation work. Certain waste handling activities may be prohibited. As specified in MN Rules ch. 4725, a private well cannot be constructed within 150 feet of a landfill without a regulatory-approved variance.


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Additional location-specific ARARs include, but are not limited to, the following:

County and state road weight restrictions Minnesota Department of Transportation (Mn/DOT), county and city

utility easement permitting MCES sewer expansion and connection approval MN Rule sec. 7077.0105. Modifications to sanitary sewers to provide

new or improved services MN State Building and Fire Code National Fire Protection Association (NFPA) 70, National Electrical

Code

2.3 Action-Specific Requirements Specific remedial activities selected to accomplish site cleanup are regulated or controlled by action-specific ARARs. Action-specific requirements regulate how a selected alternative must be accomplished. Example action-specific ARARs are discussed herein as they may pertain to possible remedial alternatives.

The Federal Occupation Safety and Health Administration (OSHA) includes several regulations regarding remediation, excavation, and construction activities; general facility requirements related to handling wastes; and regulations related to transportation of solid wastes over public highways.

Several State of Minnesota regulations may apply to specific actions potentially implemented at this site. These regulations include, but are not limited to, the series on water quality, air quality, solid waste handling, on hazardous waste and state building safety requirements. Significant portions of these action-specific ARARs include, but are not limited to:

MN Rules ch. 4715. Minnesota Plumbing Code MN Rules ch. 4720. Minnesota Public Water Supply Code MN Rules ch. 4725. Water Well Code MN Rules sec. 7001.0610. Land Treatment of Hazardous Waste MN Rules ch. 7035. Solid Waste

− Section 0450 – Demonstration/Research Projects − Section 0800 – Collection and Transport of Solid Waste − Section 2565 – Groundwater Quality, Surface Water Quality, and Air

Quality and Soil Protection − Section 2610 – Construction Certification − Section 2815 – Mixed municipal solid waste land disposal facilities

MN Rules ch. 7050. Waters of the State MN Rules ch. 7045. Hazardous Waste MN Rules ch. 7090. Stormwater Regulatory Program MN Statute 115 Water Pollution Control; Sanitary Districts 40 Code of Federal Regulations (CFR) Part 122. EPA Administered

Permit Programs: The National Pollutant Discharge Elimination System


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40 CFR Part 260. Hazardous Waste Management System: General 40 CFR 260. Land Disposal Restrictions 49 CFR Parts 171-179. DOT Hazardous Materials Transportation Safety

Act Minnesota Department of Natural Resources (MDNR) Appropriations of

Waters Permit

Section 3 – Remedial Action Alternatives


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3.0 Remedial Action Alternatives This section presents and evaluates the remedial action alternatives that have been selected by the MPCA Closed Landfill Program. The six potential remedial options evaluated include:

No Additional Action Plasma Torch Force Main (groundwater extraction with off-site disposal Pump and Treat (groundwater extraction with treatment or infiltration

on-site) Dig and Truck Dig and Line

3.1 Primary Remedial Action Alternative Development Assumptions

Several assumptions were necessary to develop the different remedial action alternatives and associated cost estimates. Additional assumptions, specific to a remedial action alternative, are presented in the descriptions section of the respective alternative. Common assumptions to each alternative are presented below.

Local roads and highways would be available for transportation of equipment, waste materials, and/or new backfill.

Remediation activities would not be conducted at the spray irrigation infiltration basin.

Workers would utilize appropriate personal protective equipment to minimize the potential for exposures to contaminants.

City, county, state, or federal agencies would not prohibit the actions outlined by the passage of new laws or ordinances, and/or would not formally act to prevent associated variances.

The landfill contents are not considered hazardous wastes. Remedial activities are not required for the ponded surface waters. The community (local residents, businesses, and public interest groups)

would not object to any of the alternatives or associated disruptions, provided that risk issues are addressed properly and work is conducted within normal constraints (work hours, safety issues, noise and odor controls, etc.).

3.2 Evaluation Criteria

Remedial action options are evaluated according to the CERCLA “Threshold” and “Primary Balancing” criteria outlined in 40 CFR Part 300.430(e)(9)(iii)(A-I). As directed by the MPCA, SEH has not evaluated the remedy options against the USEPA’s modifying criteria: Agency Acceptance and Public Acceptance.

The threshold criteria of an option are evaluated according to:

Overall Protection of Human Health and the Environment Compliance with ARARs


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The balancing criteria of an option are evaluated according to:

Long-Term Effectiveness and Permanence Reduction of Toxicity, Mobility, or Volume (TMV) Through Treatment Short-Term Effectiveness Implementability Cost

Each of the criteria is further described below.

3.2.1 Overall Protection of Human Health and the Environment The assessment against this criterion describes how the alternative, as a whole, achieves and maintains protection of human health and the environment. This protection is a result of eliminating, reducing, or controlling exposure risks. The evaluation of remedial alternatives in regard to health risk is conducted in general accordance to the Risk Assessment Guidance for Superfund (RAGS): Volume I – Human Health Evaluation Manual, Part C, Risk Evaluation of Remedial Alternatives (USEPA, 1991b).

3.2.2 Compliance with ARARs Under this criterion, an alternative is assessed in terms of its compliance with federal and state ARARs, unless a waiver can be justified. ARARs are divided into three types:

Chemical Specific (i.e., Minnesota Rules Chapter 4717.75 – HRL Table ) Location Specific (i.e., road weight restrictions) Action Specific (i.e., Landfill Design Criteria)

3.2.3 Long-Term Effectiveness and Permanence

Long-term effectiveness and permanence assesses the degree to which the toxicity, mobility and volume of the contamination are reduced as well as an assessment of long-term human health and ecological impacts, after the remedy is complete. (Based on previous studies and reports, no ecological impacts have been identified; therefore, ecological targets will not be considered in this RFA (USEPA, 2004)).

Long-term human health impacts are those associated with residual contamination, if any, after the remedy is complete, as well as risks associated with the final disposition of relocated wastes.

3.2.4 Reduction of Toxicity, Mobility, or Volume (TMV) Through Treatment This criterion assesses the degree to which each alternative employs permanent reduction of the toxicity, mobility, or volume of substances of concern which pose a threat to human health and the environment.

3.2.5 Short-Term Effectiveness Short term effectiveness includes an assessment of potential short-term human health impacts during implementation of the remedy.

Short term human health impacts include risks to the community, as well as to workers involved in the remediation during implementation of the remedy.


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3.2.6 Implementability Implementability takes into account several factors including:

Constructability Availability of services and materials Reliability of technology Monitoring considerations Ease of undertaking additional remedial action Compliance with ARARs Administrative requirements

3.2.7 Cost

Cost analysis of an option includes the following:

Initial capital costs Annual operations, maintenance, and monitoring (OMM) costs Present worth total costs (including long-term OMM costs calculated to

present worth using a 5% discount factor) Annualized total costs (with initial capital costs amortized over long-

term care period) Unless specified otherwise in each remedial action alternative cost

discussion, long-term OMM costs and amortization schedules are based on a 40-year schedule.

The costs analysis does not consider other less tangible factors which might be associated with either leaving the contamination unabated or with the remedial action disturbances. These factors may include impacts to tourism, future development, real estate valuation, indirect health care, or natural resource degradation.

3.3 Detailed Evaluation of Remedial Alternatives This section details the evaluation of the remedial alternatives the MPCA requested SEH to consider. The alternatives have been evaluated against the criteria described above. A summary of the evaluation is presented on Table 1, “Summary of Criteria Evaluation.”

3.3.1 Remedial Alternative: No Additional Action The “No Additional Action” alternative is evaluated to provide a baseline for public health and welfare and environmental consequences of taking no further remedial action at the site. This alternative was initially labeled as the “Do Nothing” alternative; however, since some remedial activities will continue at the site with this alternative, SEH changed the name to more accurately reflect the approach. It is understood that the existing remedial and monitoring effort would continue; however, further investigation and/or remediation with regards to PFC’s would cease.


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Background Current remedial activities at the site are understood to include groundwater recovery and treatment of VOCs via a spray irrigation system. The VOC treated groundwater is discharged to an infiltration area located near the southeast corner of the landfill. Groundwater is pumped from well GC-1, GC-3, and GC-5. Recovery wells GC-3 and GC-5 were installed in 2006. Based on groundwater flow and contaminant transport modeling results presented by Barr, the MPCA, and others, historic groundwater recovery has been insufficient to capture PFC contaminants released to the groundwater from the landfill, especially with recharging infiltration from the spray irrigation system. The current pumping rates at each well are unknown. It is assumed that the current groundwater recovery program is insufficient to provide capture of the contaminant plume. The spray irrigation system is not believed to be providing treatment of the PFC constituents.

Description The No Additional Action alternative includes continued OMM of the LFG extraction and flare system, routine monitoring of the groundwater monitoring network and regularly scheduled maintenance of the landfill cover system for a forty-year long-term care period. It is assumed for the cost evaluation that a new landfill cover will be installed within five years. The maintenance of existing GAC treatment systems and provision of bottled water at select residences is also assumed to be maintained for a forty-year long-term care period.

3.3.1.1 Overall Protection of Human Health and the Environment This alternative allows for a new landfill cover within five years. Infiltration will continue through the waste until the new cover is constructed. A new cover system reduces or eliminates future infiltration through the waste, potentially slowing the migration of contaminant concentrations through the groundwater. It is likely that migration of PFCs will continue, however, because the bottom of the waste appears to be located within or near the groundwater table.

Risks to human health via groundwater ingestion and dermal contact may be addressed for 40 years for residents receiving GAC treatment or bottled water. This alternative may not account for spreading of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

The spray irrigation system would continue operation under this alternative. The irrigation system addresses the off-site migration of VOCs, but has not prevented the risk of ingestion or dermal contact with PFCs to off-site receptors. The irrigation system may have caused the contamination of surface and subsurface soils in the infiltration basin with PFCs. The spray irrigation system has created a route of exposure to occupational workers and trespassers through incidental ingestion and dermal contact with the surface soils in the infiltration basin area. Construction of a new landfill cover will not eliminate this risk in the short-term or long-term as the irrigation system


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continues operation. This alternative does not address the risk of incidental ingestion and dermal absorption by occupational workers that may have future exposure to subsurface landfill soil and/or groundwater contaminants.

The LFG extraction and flare systems will continue operation under this alternative and appear to be effective in preventing the migration of subsurface gases including explosive methane and VOCs off site, thus reducing the risk of indoor air exposure to residents. This alternative does not address the relatively low risk potential by the migration of volatile contaminants directly from the site to ambient air, providing an exposure pathway to near-by residential and recreational populations and on-site occupational workers and trespassers.

Short-term risk associated with construction of the new landfill cover includes the occupational incidental ingestion and dermal absorption of surface water and soils. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment.

3.3.1.2 Compliance with ARARs This alternative would not meet the ARARs associated with source control for groundwater protection. PFC constituents in several monitoring wells and private wells are above the respective HRLs. This alternative does not provide complete capture of the PFC groundwater contamination beneath the landfill and does not provide PFC treatment for the groundwater collected.

3.3.1.3 Long-Term Effectiveness and Permanence This alternative does not provide long-term effectiveness and permanence. The existing groundwater recovery system is currently not providing complete capture of the groundwater contaminant plume. Groundwater treatment using the spray irrigation system is not effective in removing PFC contamination from the recovered groundwater.

Under this alternative waste would continue to reside in or near groundwater likely resulting in further leaching of contaminants. A new landfill cover may limit infiltration of surface water through waste but migration of contaminants will still occur since the existing landfill does not contain an impermeable liner system.

3.3.1.4 Reduction in Toxicity, Mobility, or Volume This alternative would not reduce the TMV of contaminants or waste at the site. As specified in USEPA’s Conducting Remedial Investigations/Feasibility Studies for CERCLA Municipal Landfill Sites guidance document, technologies that do not provide treatment do not require evaluation under this criterion (USEPA, 1991a).

3.3.1.5 Short-Term Effectiveness There is technically no short-term effectiveness with the No Additional Action alternative as no new remedy is being implemented. However, a new cover system is proposed under this alternative as part of the OMM effort.


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The short-term effectiveness of replacing the landfill cap is moderate given the relative risk to human health and the environment would increase during implementation of the remedy due to extensive site construction activities and likely waste exposure. This risk could be managed accordingly with an appropriate health and safety program and applicable engineering controls.

3.3.1.6 Implementability This option, while technically feasible, is unlikely to be implemented since it does not comply with applicable ARARs.

There are no significant concerns regarding constructability, availability, monitoring, or ease of undertaking additional remedial action.

3.3.1.7 Costs The preliminary projection of initial capital and long-term annual costs for this option are approximately $5,000,000 and $120,000 per year, respectively. Long-term costs include routine OMM of the landfill and ongoing OMM costs associated with the existing private well GAC treatment systems. It is assumed the private well GAC systems would be maintained for at least 40 years since hydraulic control of the groundwater contamination is not provided.

The 40-year present worth cost is approximately $7,100,000. Cost estimate information for the continued level of effort alternative is provided on Table 2, “Comparison of Remedial Action Alternatives.” A detailed cost estimate spreadsheet is provided in Appendix B, “Preliminary Engineering Cost Projections.”

3.3.2 Remedial Alternative: Plasma Torch This alternative involves excavating the waste material from the landfill and converting the waste onsite to gas and inert slag material using plasma torch technology.

Background

The Washington County Landfill Alternative Selection Matrix-Costs (Cost Matrix) prepared by the MPCA included a cost estimate for the plasma torch option. Costs used to derive the total cost number ($450,000,000) were reportedly based on capital costs provided in a Popular Science article (Behar, March 2007). The Cost Matrix is included in Appendix C, “MPCA Cost Matrix.”

SEH contacted John Howard, CEO of Coronal Plasma Gas Solutions, to obtain a better understanding of the technology with respect to site specific considerations. Mr. Howard indicated that the approach discussed in the Popular Science article was geared primarily towards the management of municipal solid waste (MSW) recently generated (new waste). The Popular Science article project involved gasification and use of heat from the combustion process to generate electricity to fuel the plasma torch process. Mr. Howard indicated new MSW would likely be required to supplement the waste removed from the Washington County Landfill to facilitate gasification and electricity generation. New MSW has a higher heat energy potential (measured in British thermal units (Btus)) than aged waste removed


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from a closed landfill since it has not yet been subjected to degradation processes (Howard, 2007).

Mr. Howard did indicate that plasma conversion could be used effectively to “destroy” the waste from the Washington County Landfill without energy recovery. The capital investment associated with this process is much lower than the capital costs presented in the Popular Science article. However, since electricity is not generated to fuel the plasma torch, a large amount of off-site electricity would be needed to complete the process (Howard, 2007). For purposes of evaluating this option for the Washington County Landfill, SEH assumes that new waste would not be used to supplement the waste excavated. SEH’s cost estimate is based on unit costs and capacities provided by Mr. Howard during a telephone conversation.

Description Forty 1.5 Megawatts (MW) plasma torches and 10 plasma vessels are necessary to destroy 2,000 tons of waste, cumulatively, per day. A 2,000 ton/day target was selected as it would result in the management of waste at approximately the same rate presented in the Dig and Truck option. Assuming a 100% operation capacity of the plasma system, it would take approximately 3.5 years to destroy 2,500,000 tons of waste. By-products of the plasma conversion process include syngas (hydrogen and carbon monoxide gas) and slag (obsidian-like glass). The slag is generated from the waste at a ratio of approximately 10:1 (waste : slag) by volume and 5:1 by mass. The slag is reportedly a saleable product. The maximum electric use for each torch is 1.5 megawatts (MW); however, the electric requirement of each torch is dependent on the Btu capacity and density of the waste. Therefore, it is likely that the estimated electricity requirements would be less than 1.5 MW per torch. For purposes of SEH’s evaluation, it was assumed that each torch would require the maximum electric demand.

Prior to excavating waste, the groundwater recovery and infiltration system would be shut down and the private well GAC treatment system program would be expanded similar to the Dig and Line and Dig and Haul alternatives. Landfill cover soils would be removed and stockpiled for future re-placement. Temporary access roads would be installed as the waste excavation progresses. It is assumed that the void created by the waste excavation would be graded to minimize excessive slopes and the landfill cover soils would be re-placed and seeded.

The following assumptions were utilized in evaluating this alternative:

Information prepared and presented by others and/or provided to SEH by MPCA has been accepted in good faith and is assumed to be accurate unless written documentation, available within the scope of this RFA, contradicted it.

Volume of waste at site is 2,500,000 cubic yards. Waste mass is 1 ton/cubic yard.

Supplemental waste would not be provided for Plasma Torch. An energy recovery system is not included. The groundwater recovery and infiltration system would be shut down

for the duration of the project excavation.


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Private well GAC treatment systems and/or bottled water would be provided to residences potentially impacted by the plume migration associated with shutting down the groundwater recovery and infiltration system.

Air emission control systems would not be required. Available portions of the LFG extraction system would be operated

during waste excavation. The LFG barrier vent system would be reactivated. Landfill cover materials would be applied to the open portion of the

existing landfill at the completion of each day of excavation. Leachate pumping, treatment, or disposal would not be required during

waste excavation. Annual OMM effort would be approximately 30% of existing effort

(groundwater monitoring) and would be terminated within 10 years of completion of the waste excavation activities. The decreased effort is due to elimination of routine OMM associated with the landfill and accounts for continued monitoring of existing monitoring wells.

Maintenance of the existing private well GAC treatment systems and bottled water program will continue for a period of 10 years.

A health and safety program relating to the waste excavation would be implemented.

Advantages of this alternative include: Involves contaminant source removal Requires minimal ongoing OMM effort compared to onsite groundwater

treatment Eliminates long-term liability associated with waste relocation

Disadvantages include: Labor intensive technology Not a mature technology with a proven track record May result in plume migration Increased off-site exposure risks Significant on-site exposure risks Substantial electrical service required


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3.3.2.1 Overall Protection of Human Health and the Environment This alternative removes the waste and contaminants from the landfill eliminating release of contaminants to the groundwater and air and off-site migration within a period of three to four years. Because the groundwater recovery and landfill gas management systems would not be in use during waste removal and conversion, off-site releases through groundwater and ambient air migration may occur. For a period of 10 years, risks to human health via groundwater ingestion and dermal contact would be addressed for residents receiving GAC treatment or bottled water. This alternative may not account for further down gradient migration of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

This alternative also does not eliminate the relatively low risk on- or off-site due to volatilization of contaminants directly to the ambient air during the waste conversion period, providing an exposure pathway to near-by residential and recreational populations and on-site occupational workers and trespassers.

Once the waste has been excavated and converted, exposure pathways would not exist, thus permanently eliminating most routes of exposure to the contaminants of concern. This alternative does not address surface and subsurface soils that have become contaminated in the infiltration basin. This contamination source would still remain and continue to present a route of exposure to occupational workers and trespassers.

Short-term risk associated with excavation and the plasma torches includes occupational incidental ingestion and dermal absorption of surface soils and a significant risk due to incidental ingestion and dermal absorption of subsurface soils and groundwater. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment. Landfill excavation also poses an occupational risk due to potential for explosive gases igniting. A risk to occupational workers also exists due to potential exposure to the high voltage required for this alternative.

3.3.2.2 Compliance with ARARs This alternative would meet the ARARs associated with source control for groundwater protection. Removal of waste and destruction using plasma source technology would result in contaminant source control. By removing the waste, contaminant contribution to groundwater should decrease, providing a mechanism to attain ground water quality standards. Since the groundwater recovery system would be shut down during excavation of waste, the potential for contaminant migration would increase. However, residences having the potential to be impacted by an expanded plume would be provided with a private well GAC treatment system.


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This alternative would be designed, implemented, operated, and maintained in accordance with Federal and State ARARs. Variances to the ARARs may be required in the event that the assumptions generated during the evaluation of this alternative are incorrect.

3.3.2.3 Long-Term Effectiveness and Permanence Plasma Torch technology is a relatively new and emerging technology to destroy solid waste. Accordingly, limited information or experience regarding the reliability of the technology is available. The primary focus of this alternative is on the removal of waste, with plasma torch technology being the means of managing the waste. Removal of the source is the most effective method of eliminating on-going contamination and attaining permanence.

3.3.2.4 Reduction in Toxicity, Mobility, or Volume Excavation and destruction of the source is the most effective method to reduce the TMV of its resulting contaminants.

3.3.2.5 Short-Term Effectiveness Short-term human health risks would be increased during implementation of the remedy due to physical hazards and increased potential for exposure to the contaminants. Engineering controls and safety measures would be utilized to limit the potential for increased exposures.

3.3.2.6 Implementability This alternative would likely be implementable due to the landfill’s relatively rural location, compliance with applicable ARARs, and following completion, protectiveness of human health and the environment. However, plasma torch technology is new and emerging with only a few working applications similar to what would be necessary at the Washington County Landfill. Accordingly, implementability and operational uncertainties exist.

Monitoring the effectiveness of Plasma Torch should be relatively routine; however, availability of services and materials may be limited and specialized by comparison to other, more mature technologies. Another concern regarding implementability is the need for a very large electricity source. It is unlikely that this requirement could be fulfilled by the current electric infrastructure at or near the landfill. Accordingly, the necessary infrastructure would need to be constructed. An evaluation of this alternative assumes that this construction is feasible.

3.3.2.7 Costs The preliminary projection of initial capital cost for this option is approximately $192,300,000. Since it is estimated that OMM and electricity requirements for the Plasma Torch system would be necessary for less than 3.5 years, these costs were included as capital costs. The preliminary projections of 10-year long-term care costs are approximately $87,000. Long-term 10-year costs include ongoing OMM costs associated with the expanded private well GAC treatment system network and limited monitoring of the groundwater network following waste excavation.


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The 10-year present worth cost is approximately $193,000,000. Cost estimate information for the Plasma Torch alternative is provided on Table 2. A detailed cost estimate spreadsheet is provided in Appendix B.

3.3.3 Remedial Alternative: Force Main This remedial alternative involves pumping groundwater (much like the Pump and Treat option) and discharging the untreated water to a force main, which discharges to a waste water treatment facility. This option would require the construction of a force main from the landfill to the nearest sanitary sewer.

Background Barr included groundwater removal and disposal to a sanitary sewer in their June 29, 2005 feasibility study for the Washington County Landfill (Barr, 2005). In 2007, URS Corporation (URS) completed a preliminary construction cost estimate for the project assuming the force main would be constructed from Jamaca Avenue North (City of Lake Elmo) to an existing manhole in Granada Avenue North (City of Oakdale) (URS, 2007a). Included with URS’s cost estimates was a clarification of service and disposal fees associated with the project. Recovered groundwater would be pumped to the City of Oakdale’s sanitary system via the force main. Once in Oakdale’s sanitary system the water would discharge to the MCES waste water treatment plant. URS’s cost estimate, Engineers Estimate of Quantities, and clarification of disposal and services fees is provided in Appendix D, “URS Information.”

URS provided cost detail for two alternative approaches to install the force main. One alternative utilizes open cut construction for the majority of the force main length, with directional boring at major road crossings. The second option utilizes directional boring the entire force main length. The cost difference between the two options was presented as $35,500 with the open cut option being the least expensive. It appears that the MPCA prefers the open cut option as the costs associated with this approach were presented on the Cost Matrix (included in Appendix C) provided to SEH. Accordingly, our evaluation assumes that force main construction would be performed using the open cut approach.

Description Based on groundwater flow and contaminant transport modeling results presented by Barr, optimal pumping rates to provide capture of the contaminant plume, without infiltration or injection to the aquifer, would require a pumping rate of at least 65 gpm from GC-1 and 50 gpm from GC-5 (115 gpm cumulative). Assuming continuous operation of the groundwater recovery system, the annual cumulative discharge to the Oakdale sanitary system and MCES treatment plant would be approximately 60.4 million gallons.

URS’s cost estimate letter indicated the City of Oakdale would require a one-time sewer access charge (SAC) to connect the force main to the sanitary system. The connection fee is per SAC unit (1 SAC unit = 274 gallons/day) at a rate of $500 per SAC unit. In addition, the City of Oakdale would assess an annual sanitary usage rate of $2.88 per 1,000 gallons and MCES would


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assess an annual contaminated groundwater charge Add-on Service Charge of $0.84 per 1,000 gallons (2007 rates).



Force main installation would be completed using open cut trench methods.

URS’s preliminary design is appropriate for the current designed flows (115 gpm).

URS’s cost detail did not include estimates for engineering and construction oversight; accordingly, these items were estimated by SEH as a percentage of capital costs.

OMM of the force main and lift station would be conducted for a long term care period of 40 years.

Groundwater recovery wells GC-1 and GC-5 exist and are operable. The conveyance network exists to deliver recovered groundwater to the treatment system.

A groundwater recovery rate of 65 gpm from GC-1 and 50 gpm from GC-5 (115 gpm cumulative) is adequate to provide complete capture of the horizontal and vertical extent of groundwater contamination.

Pre-treatment is not required prior to discharge to MCES. No pre-treatment standards exist for PFCs. Continued OMM of the LFG extraction and flare system will continue

for 40-year long term care period. A new landfill cover system would be installed within 5-years. Continued maintenance of the existing private well GAC treatment

systems and bottled water program for a period of 10-years.

Advantages of this alternative include: Involves gradient control and minimizes the potential for contaminant

migration in the groundwater aquifers. Remedial equipment necessary for this technology readily available with

standard maintenance requirements Requires minimal ongoing OMM effort compared to onsite groundwater

treatment

Disadvantages include: Does not involve contaminant source removal Does not provide mass reduction of contaminants from the environment

as typical WWTP treatment processes do not remove or degrade PFCs Remedial activities likely required indefinitely, or until the source is

removed


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If a leak occurs in the force main it is possible it would go undetected, and result in contamination of a previously non-impacted area.

3.3.3.1 Overall Protection of Human Health and the Environment

This alternative provides gradient control and contaminant removal preventing the future migration of contaminants to off-site receptors through the groundwater. Risks to human health via groundwater ingestion and dermal contact may be addressed for 10 years for residents receiving GAC treatment or bottled water. This alternative may not account for further down gradient migration of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

If the force main fails, contaminants may again be released off site and possibly not be detected. This may result in previously uncontaminated areas becoming impacted. An uncontaminated area would now potentially be subject to exposure risk due to ingestion and dermal contact.

Similarly, if the pumps fail, gradient control may be lost and contaminated groundwater and/or leachate could be released off site. Under this alternative, there would be no additional risk posed if the residents receiving GAC treatment or bottled water are still receiving GAC treatment or bottled water. If the pumps fail after the GAC treatment systems are no longer in use, there may be risk due to ingestion and dermal contact with the groundwater.

This alternative does not address the risk of incidental ingestion and dermal absorption by occupational workers that may have future exposure to subsurface soil and/or groundwater contaminants.

The LFG extraction and flare systems would continue operation under this alternative and appear to be effective in preventing the migration of subsurface gases off site, eliminating the risk of indoor air exposure to residents. This alternative does not address the relatively low risk migration of volatile contaminants directly from the site to ambient air, providing a relatively low risk exposure pathway, to near-by residential and recreational populations and on-site occupational workers and trespassers.

This alternative does not address surface and subsurface soils that may have become contaminated in the infiltration basin. This contamination source would still remain and continue to present a route of exposure to occupational workers and trespassers.

Short-term risk associated with construction of the new landfill cover and force main includes the occupational incidental ingestion and dermal absorption of surface soils. Potential releases to the subsurface soils and groundwater during pressurized testing of the force main results in a risk due to ingestion and dermal contact with groundwater by off-site receptors and response workers. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment.


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3.3.3.2 Compliance with ARARs This alternative would meet the ARARs associated with source control for groundwater protection. PFC contamination in groundwater would be contained under this alternative. It is SEH’s understanding that the MCES does not have pretreatment standards for PFCs discharged to their treatment system; therefore discharge of PFC contaminated groundwater would be in compliance with ARARs. However, it is reasonable to assume that regulations regarding PFC discharges will be forthcoming since it has been determined that most PFC constituents essentially pass through conventional WWTP treatment processes. The pass through of PFC constituents at a WWTP, if it is determined to be detrimental to the treatment process, would be considered an exceedance of an ARAR.

It is assumed the force main alternative would be designed, installed, operated, and maintained in accordance with applicable State and Federal ARARs. These applicable ARARs would likely be identified during the detailed design stage.

3.3.3.3 Long-Term Effectiveness and Permanence The force main alternative would be effective in removing contaminated groundwater from the site, but it does not include the provisions of source control and would likely need to operate indefinitely to prevent further offsite migration of groundwater contamination. Studies indicate that treatment processes employed at WWTP’s have limited success for removal or treatment of PFC in the wastewater. In addition, sludge generated from the treatment process also contains PFCs, which may affect disposal options (MPCA, 2006). In the event pretreatment standards are promulgated for PFCs, the long-term effectiveness and permanence of this alternative would be poor.

Installing a landfill cover would limit infiltration of surface water through waste. However, waste would continue to reside in or near groundwater likely resulting in further leaching of contaminants. As such, some risk remains associated with the long-term effectiveness in preventing off-site migration of groundwater contamination.

3.3.3.4 Reduction in Toxicity, Mobility, or Volume Reduction in TMV of contamination within groundwater results from hydraulic control of the contaminant plume, removal of impacted groundwater, and discharge to the MCES. Reduction of TMV is not accomplished with respect to the source (waste) nor as the result of discharge to the MCES. There is no reduction of TMV for PFCs at MCES.

3.3.3.5 Short-Term Effectiveness The short-term effectiveness of the force main system is moderate given that the relative risk to human health and the environment increases due to off-site construction activities potentially impacting the public. The risks associated with site construction activities can be managed with an appropriate health and safety program and applicable engineering controls.


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A new cover system is proposed under this alternative as part of the OMM effort. The short-term effectiveness for replacing the landfill cap is moderate given that the relative risk to human health and the environment would increase during implementation of the remedy due to extensive site construction activities and likely waste exposure. The risk associated with cover replacement would be managed with an appropriate health and safety program and applicable engineering controls.

3.3.3.6 Implementability This alternative would likely be implementable since it complies with current applicable ARARs.

All components of the alternative are implementable as services and equipment necessary to install, maintain, and monitor this alternative are readily available.

Undertaking further remedial action at this site would be easy for the force main option. Once a new landfill cover is installed on the landfill, implementation of supplemental remedial action on the landfill would become more difficult due to disturbance of the impermeable seal. Otherwise, there are no significant concerns regarding constructability, availability, or monitoring.

3.3.3.7 Costs The preliminary projection of initial capital cost for this option is approximately $7,300,000. The preliminary projections of 10-year and 40-year long-term care costs are approximately $30,000 and $420,000 per year, respectively. Long-term 40-year costs include annual routine OMM of the landfill and OMM for the groundwater pumps, force main, and lift station. Also included with the 40-year costs are annual sewer use and discharge fees. Long-term 10-year costs include ongoing OMM costs associated with the existing private well GAC treatment systems.

The 40-year present worth cost is approximately $14,800,000. Cost estimate information for the force main alternative is provided on Table 2. A detailed cost estimate spreadsheet is provided in Appendix B.

3.3.4 Remedial Alternative: Pump and Treat The existing spray irrigation system installed at the site has historically been successful in treating VOC impacted water recovered from the site groundwater extraction wells. However, the spray irrigation system is not believed to be providing treatment of the PFC constituents. Supplemental treatment is required to remove PFCs to below the applicable HRLs or MDH drinking water well advisories from the recovered groundwater.

Background Conestoga-Rovers & Associates (CRA) conducted several bench and pilot scale tests to attempt to remove PFCs from recovered on-site groundwater. CRA tested the effectiveness of several DOWEX ion exchange resins and GAC in removing PFCs from groundwater. Results of the studies indicated that GAC and several of the DOWEX resins were generally equally effective in removing PFCs, and had similar break through characteristics. CRA


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concluded that GAC was the most viable adsorbent (CRA, August 30, 2007a).

CRA also evaluated the effect pH adjustment had on removal and breakthrough efficiencies of the GAC media. CRA concluded that adsorption capacity of GAC significantly increased by lowering the pH value to three. However, the net mass removal per unit of treatment media was not substantial enough to off-set the additional costs of pre- and post-treatment pH adjustment requirements (CRA, September 14, 2007).

It is SEH’s understanding that CRA’s final recommendation regarding groundwater treatment utilized GAC with no pH adjustment. The treatment system design and costs utilized in SEH’s evaluation are based on CRA’s document titled Appendix D, Revised Cost Estimate for the Groundwater Treatment System at the Washington County Landfill (CRA, August 30, 2007b) minus costs associated with pH adjustment. Treatment design assumptions utilized by CRA include a treatment system influent flow rate of 150 gpm and a PFBA concentration of 485 ug/l. CRA’s design letters and cost estimates are attached in Appendix E, “CRA Information.”

Based on groundwater flow and contaminant transport modeling results presented by Barr (Barr, 2005), optimal pumping rates to provide capture of the contaminant plume would require a pumping rate of at least 90 gpm from GC-1 and 50 gpm from GC-5 (140 gpm cumulative). This scenario assumes treated water infiltration in the southeast infiltration basin continues. The MPCA’s groundwater modeling effort indicated similar results (100 gpm from GC-1 and 45 gpm from GC-5). For purposes of this evaluation it is assumed that a cumulative flow of 150 gpm would be the targeted groundwater recovery flow rate.

Description For the pump and treat option it is assumed that groundwater recovery would occur at GC-1 and GC-5 at the minimum flow rates discussed above. Recovered groundwater would be conveyed to a large equalization tank. Groundwater treatment would be conducted in the equalization tank where bubbling would remove VOCs. CRA’s design indicated water from the equalization tank would pass through two Birm media filters to remove iron precipitate from the groundwater and through two GAC vessels for PFC treatment. Treated groundwater would discharge directly to the southeast infiltration basin. CRA’s design also included a backwash system for the iron removal process, an iron sludge precipitate tank, a sludge holding pond, several pumps, and the instrumentation to operate the treatment and material conveyance process. A detailed description of the system process flow is provided in Appendix E.



The recommended groundwater treatment option utilizes GAC with no pH adjustment.


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OMM of the groundwater treatment system would be conducted for a long-term care period of 40 years.

Groundwater recovery wells GC-1 and GC-5 exist and are operable. The conveyance network exists to deliver recovered groundwater to the treatment system.

A groundwater recovery rate of 100 gpm from GC-1 and 45 gpm from GC-5 (145 gpm cumulative) is adequate to provide complete capture of the horizontal and vertical extent of groundwater contamination.

There are no regulatory issues regarding discharging treated water to the ground surface.

OMM of the LFG extraction and flare system would continue for a 40-year long-term care period.

A new landfill cover system would be installed within 5-years. Maintenance of the existing private well GAC treatment systems and

bottled water program would continue for a period of 10 years. Conveyance piping is in place from GC-1 and GC-5.

Advantages of this alternative include: Involves contaminant removal and gradient control GAC treatment is a mature remedial technology with documented

success. Remedial equipment necessary for this technology is readily available

with standard maintenance requirements. There are numerous GAC vendors available to provide GAC media.

Disadvantages include: No contaminant source removal It is likely that remedial activities would be required indefinitely (at least

40 years), or until the source is removed. Labor and maintenance intensive technology


This alternative provides gradient control and contaminant removal preventing the future migration of contaminants to off-site receptors through the groundwater. Risks to human health via groundwater ingestion and dermal contact may be addressed for 10 years for residents receiving GAC treatment or bottled water. This alternative does not account for further down gradient migration of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

If the Pump and Treat system fails, contaminants may again be released off site, as contaminants will always remain in the waste and the on-site groundwater. Under this alternative, there will be no additional risk posed if the residents receiving GAC treatment or bottled water are still receiving


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private groundwater treatment or bottled water. If the pumps fail after the private groundwater treatment systems are no longer in use, there may be risk due to ingestion and dermal contact with the groundwater.

This alternative does not address the risk of incidental ingestion and dermal absorption by occupational workers that may have future exposure to subsurface soil and/or groundwater contaminants. This alternative also does not address surface and subsurface soils that may have become contaminated in the infiltration basin. This contamination source will still remain and continue to present a route of exposure to occupational workers and trespassers.

The LFG extraction and flare systems would continue operation under this alternative and appear to be effective in preventing the migration of subsurface gases off site, eliminating the risk of indoor air exposure to residents. This alternative does not address the relatively low risk posed by the migration of volatile contaminants directly from the site to ambient air, providing a low risk exposure pathway to near-by residential and recreational populations and on-site occupational workers and trespassers.

Short-term risk associated with construction of the new landfill cover and on-site treatment system includes the occupational incidental ingestion and dermal absorption of surface water and soils. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment.

3.3.4.2 Compliance with ARARs This alternative would meet the ARARs associated with source control for groundwater protection. PFC contamination in groundwater would be contained under this alternative and GAC treatment would remove contaminants in recovered groundwater below applicable regulatory limits.

It is assumed the Pump and Treat alternative would be designed, installed, operated, and maintained in accordance with applicable State and Federal ARARs. These applicable ARARs would likely be identified during the detailed design stage.

3.3.4.3 Long-Term Effectiveness and Permanence The Pump and Treat alternative would be effective in removing and treating contaminated groundwater, but it does not include the provisions of source control and would likely need to operate indefinitely to prevent further offsite migration of groundwater contamination. GAC treatment technology is a mature technology with a proven record of effectiveness.

Installing a landfill cover would limit infiltration of surface water through waste. However, waste would continue to reside in or near groundwater likely resulting in further leaching of contaminants. As such, a level of risk remains associated with the long-term effectiveness in preventing off-site migration of groundwater contamination.


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3.3.4.4 Reduction in Toxicity, Mobility, or Volume Reduction in TMV of contamination within groundwater results from hydraulic control of the contaminant plume, removal of impacted groundwater, and treatment using GAC. Reduction of TMV is not accomplished with respect to the source (waste).

3.3.4.5 Short-Term Effectiveness The short-term effectiveness of the Pump and Treat system is good given that the relative risk to human health and the environment would not significantly increase during implementation of the remedy. All construction activities associated with this alternative will be performed on site. The risks associated with site construction activities can be managed with an appropriate health and safety program and applicable engineering controls.

A new cover system is proposed under this alternative as part of the OMM effort. The short-term effectiveness for replacing the landfill cap is moderate given that the relative risk to human health and the environment would increase during implementation of the remedy due to extensive site construction activities and likely waste exposure. Short-term ecological risks would also increase as the waste is exposed during construction activities. This risk associated with cover replacement would be managed with an appropriate health and safety program and applicable engineering controls.

3.3.4.6 Implementability This alternative would likely be implementable since it complies with applicable ARARs.

All components of the alternative are implementable as services and equipment necessary to install, maintain, and monitor this alternative are readily available.

Undertaking further remedial action at this site would be feasible for the Pump and Treat option. Once a new landfill cover is installed on the landfill, implementation of supplemental remedial action on the landfill would become more difficult due to disturbance of the impermeable seal. Otherwise, there are no significant concerns regarding constructability, availability, or monitoring.

3.3.4.7 Costs The preliminary projection of initial capital cost for this option is approximately $5,800,000. The preliminary projections of 10-year and 40-year long-term care costs are approximately $30,000 and $670,000 per year, respectively. 40-year long-term costs include routine OMM of the landfill and OMM for the pump and treat system. 10-year long-term costs include ongoing OMM costs associated with the existing private well GAC treatment systems.

The 40-year present worth cost is approximately $17,500,000. Cost estimate information for the pump and treat alternative is provided on Table 2. A detailed cost estimate spreadsheet is provided in Appendix B.


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3.3.5 Remedial Alternative: Dig and Truck This alternative involves excavating the waste material from the landfill and transporting and disposing of the waste off site at a licensed solid waste disposal facility.

Background The Cost Matrix (included in Appendix C) prepared by the MPCA included a cost estimate for the Dig and Truck option. Costs used to derive the total cost number ($71,750,000) were based on an estimated $45/ton cost to excavate and dispose (tipping fee) of the waste and a cost of $6 per cubic yard for trucking fees. Based on correspondence with the MPCA, the weight of excavated waste per cubic yard was assumed to be 1000 pounds (1/2 ton) per cubic yard.

SEH contacted Veolia ES Industrial Services (Veolia) to obtain a cost estimate to excavate, transport, and dispose of the waste at the Washington County Landfill. SEH provided Veolia with the volume of waste (2,500,000 cubic yards) reported to exist at the site. Based on Veolia’s and SEH’s previous experience, the mass of waste was estimated to be 2,500,000 tons (1 ton/cubic yard). The additional mass estimate accounts for daily cover materials, natural compaction, and moisture. Veolia’s provided estimated unit costs for the excavation, trucking, and disposal of waste materials (Veolia, 2007).

Description Veolia’s estimate assumed approximately 4,000 tons of waste would be removed daily using two excavators and one bulldozer. SEH included costs to install temporary haul roads to enable direct loading of the waste materials into trucks. Based on the estimated mass and anticipated daily progress, the waste excavation and hauling project would take approximately 625 days. Veolia provided two waste disposal cost estimates; one option involved transporting and disposing of waste at a local licensed municipal solid waste (MSW) landfill and the second option involved transporting and disposing of waste at a Veolia owned industrial waste landfill (Rolling Hills located in Buffalo, Minnesota). Estimated costs associated with waste disposal at the remediation waste landfill are less than one-half the costs associated with disposal at a MSW site. Since waste materials removed from the Washington County Landfill are considered remediation waste, SEH assumed waste would be transported as special/remediation waste to Rolling Hills for this evaluation.

Prior to excavating waste it is assumed that the groundwater recovery and infiltration system would be shut down and the private well GAC treatment system program would be expanded similar to the Dig and Line alternative. Landfill cover soils would be removed and stockpiled for future re-placement. Temporary access roads would be installed as the waste excavation progresses. It is assumed that the void created by the waste excavation would be graded to minimize excessive slopes and the landfill cover soils would be re-placed and seeded.


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Waste removed from Washington County Landfill would be considered special/remediation waste.

The volume of waste at site is 2,500,000 cubic yards. Waste mass is 1 ton/cubic yard.

The groundwater recovery and infiltration system would be shutdown for the duration of the project excavation and construction.

Private well GAC treatment systems and/or bottled water would be provided to residences potentially impacted by the plume migration associated with shutting down the groundwater recovery and infiltration system.


during waste excavation. The LFG barrier vent system would be reactivated. Landfill cover materials would be applied to the open portion of the

existing landfill at the completion of each day of excavation and placement.

Leachate pumping, treatment, or disposal would not be required during waste excavation.

Annual OMM effort would be approximately 30% of existing effort (groundwater monitoring) and would be terminated within 10 years of completion of the waste excavation activities. The decreased effort is due to elimination of routine OMM associated with the landfill and accounts for continued monitoring of existing monitoring wells.



Advantages of this alternative include: Involves contaminant source removal MPCA accepted remediation technology which has proven effective at

other landfill remediation sites Requires minimal ongoing OMM effort compared to onsite groundwater

treatment

Disadvantages include: Labor intensive technology May result in plume migration Significant off-site exposure risks Significant on-site exposure risks


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3.3.5.1 Overall Protection of Human Health and the Environment This alternative removes the waste and contaminants from the landfill eliminating release of contaminants to the groundwater and off-site migration within a period of a little more than one year. Because the groundwater recovery system would not be in use during waste removal, off-site releases through groundwater migration would likely occur. For a period of 10 years, risks to human health via groundwater ingestion and dermal contact would be addressed for residents receiving GAC treatment or bottled water. This alternative does not account for further down gradient migration of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

Once the waste has been excavated, exposure pathways would not exist, thus eliminating the routes of exposure to the contaminants of concern at the Washington County Landfill site. However, releases at a new landfill location may occur with potential risks similar to those attributed to the current site to populations at the new landfill location. This alternative does not eliminate the relatively low risk (on- or off-site) due to volatilization of non-PFC contaminants directly to the ambient air during the waste excavation period, providing an exposure pathway to near-by residential and recreational populations and on-site occupational workers and trespassers.


Short-term risk associated with excavation and trucking of waste to a new location includes occupational incidental ingestion and dermal absorption of surface soils, and a significant risk due to incidental ingestion and dermal absorption of subsurface soils and groundwater. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment. Landfill excavation also poses an occupational risk due to potential explosive gases igniting. In addition, this alternative has a significant risk of off-site exposure due to accidents and releases during trucking.

3.3.5.2 Compliance with ARARs This alternative would meet the ARARs associated with source control for groundwater protection. Removal of waste and placement in an offsite lined landfill would result in contaminant source control. By removing the waste, contaminant contribution to groundwater would decrease, providing a mechanism to attain groundwater quality standards. Since the groundwater recovery system would be shut down during excavation of waste, the potential for contaminant migration would increase. However, residences having the potential to be impacted by an expanded plume would be provided with a private well GAC treatment system.


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This alternative would be designed, implemented, and maintained in accordance with Federal and State ARARs. Variances to the ARARs may be required in the event that the assumptions generated during the evaluation of this alternative are incorrect. For example, for this evaluation it was assumed that the waste excavated from the landfill could be managed as remediation waste and disposed of at a licensed industrial waste landfill. If this proves false, waste would require disposal at a licensed MSW landfill at a significantly higher tipping fee.

3.3.5.3 Long-Term Effectiveness and Permanence Implementation of this alternative has been proven to be a reliable remedial technology at municipal landfills. Removal of the source and containment using a landfill liner is a very effective method of eliminating on-going contamination in the long-term. While placement of waste in a lined landfill is determined to be effective and reliable in the long-term, permanence of a landfill liner is uncertain. While relatively low, the risk of landfill liner failure and subsequent environmental impacts exist. Since this alternative involves re-placement of waste at an off-site facility, ongoing risks to groundwater associated with liner failure would be transferred to the facility which accepted the waste.

Landfills constructed in compliance of applicable State ARARs have proven effective at managing environmental risks. Continued long term OMM of the new landfill cover, leachate management, and landfill gas control systems would assist in maintenance of long-term effectiveness and permanence.

3.3.5.4 Reduction in Toxicity, Mobility, or Volume Excavation of the waste and placement in an off-site lined landfill would result in the removal of TMV of contaminants associated with the waste at the Washington County Landfill site. The Dig and Truck alternative would not reduce the TMV of contaminants already in groundwater or soils beneath the landfill or infiltration basin area. It is assumed the toxicity of contamination within groundwater would reduce via dispersion since the source of contamination is removed and contained.

Waste that is placed at an off-site lined landfill would be contained resulting in a reduction of mobility of the contaminants associated with the waste. Since the waste is not destroyed or treated, reduction in toxicity and volume would not be attained. By containing the waste, the volume and toxicity of waste would be managed with engineering controls (i.e., leachate management, LFG recovery and flare). The permanence of containment is dependent on the effectiveness of the landfill liner. The Dig and Truck alternative is not considered irreversible with respect to containment (containment can be removed) but would be irreversible with respect to impacts at the Washington County Landfill since the waste would be removed from the site.

3.3.5.5 Short-Term Effectiveness Short-term human health risks would be increased during implementation of the remedy due to physical hazards and increased potential for exposure to the contaminants. Increased risks may be posed to a large area of the community during excavation and transportation of the waste off site.


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Engineering controls and safety measures would be utilized to limit the potential for increased exposures.

3.3.5.6 Implementability This alternative would likely be implementable due to the landfill’s relatively rural location, compliance with applicable ARARs (with a variance), and following completion, protectiveness of human health and the environment.

All components of the alternative are implementable as services and equipment necessary to install, maintain, and monitor this alternative are readily available. There are no significant concerns regarding constructability, availability, or monitoring.

3.3.5.7 Costs The preliminary projection of initial capital cost for this option is approximately $66,800,000. The preliminary projections of 10-year long-term care costs are approximately $87,000. Long-term 10-year costs include ongoing OMM costs associated with the expanded private well GAC treatment system network and limited monitoring of the groundwater network following waste excavation. The 10-year present worth cost is approximately $67,500,000. Cost estimate information for the Dig and Truck alternative is provided on Table 2. A detailed cost estimate spreadsheet is provided in Appendix B.

In the event waste cannot be transported and disposed at an industrial waste facility, costs for this alternative were prepared assuming waste transportation and disposal at a MSW facility. The preliminary projection of initial capital cost for this option would be increased to approximately $146,600,000. The 10-year present worth cost would be increased to approximately $147,300,000. The preliminary projections of 10-year long-term care costs for this option are the same as the special waste disposal option. A detailed cost estimate spreadsheet for this option is also provided in Appendix B.

3.3.6 Remedial Alternative: Dig and Line The Dig and Line alternative involves removing the waste in the unlined Washington County Landfill and re-placing the waste in a newly constructed, lined landfill located onsite. Since space is not available at the site to construct a new landfill adjacent to the existing landfill, a new lined landfill would need to be constructed in the same general footprint of the existing landfill. To accommodate this requirement, the construction of a new landfill and subsequent waste excavation and re-placement would need to be conducted in stages to maximize use of available space.

Background URS prepared a detailed draft conceptual design for two alternatives to complete the Dig and Line option. Both alternatives involve excavation, replacement of waste, and landfill construction activities in six stages over the course of five years. Both new landfill construction alternatives would cover a footprint of approximately 30 acres and include a compliant landfill liner system, leachate collection system, leachate recirculation system, landfill gas management system, landfill cover system, and surface water


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management system. Both alternatives also include new access roads, use of the existing LFG blower and flare, leachate and condensate storage, and a leachate load out pad (URS, 2007b). URS’s conceptual design and attachments are provided in Appendix D.

The primary differences between the two Dig and Line alternatives evaluated by URS are as follows:

Alternative 1: The existing landfill was created by filling an old quarry which was excavated to just a few feet above the historic water table elevation. Since the groundwater recovery and spray irrigation infiltration system was started, water table elevations near the southeast portion of the property have increased approximately 20 feet.

Alternative 1 assumes continued operation of the groundwater recovery and infiltration system. To meet the five foot separation distance requirement between waste and the liner, final liner grades would be completed at an elevation between 922 and 934 feet below mean sea level (msl). Waste excavation would be completed in 5 stages and the waste excavation void (approximately 820,000 cubic yards) would be backfilled with common borrow material. Alternative 1 would also require the stockpiling and double hauling of approximately 750,000 cubic yards of waste to enable landfill cell construction in the same general landfill footprint.

Alternative 2: Alternative 2 involves constructing the new landfill liner approximately 17 feet lower than Alternative 1. This would require shutdown of the groundwater recovery infiltration system and a variance to the five foot water/liner separation distance requirement. This alternative assumes that once the groundwater infiltration system is off, groundwater elevations would return to near normal historic levels (900 feet msl). As such, the lowest portion of the Alternative 2 liner would be constructed within a few feet of the anticipated groundwater elevation.

By lowering the liner to near existing waste grades, the requirement of 820,000 cubic yards of common borrow material would be eliminated. It is also estimated that stockpiling and double hauling of waste materials would be reduced to approximately 358,500 cubic yards. URS estimated the cost difference between Alternatives 1 and 2 is approximately $8 million, with Alternative 2 being less expensive.

Description It appears that the MPCA has identified Alternative 2 as the preferred Dig and Line option as the costs associated with this approach were presented on the Cost Matrix (included in Appendix C) provided to SEH. Accordingly, our evaluation assumes the Alternative 2 approach is implemented.

Since Alternative 2 requires shutdown of the groundwater recovery and infiltration system, limited hydraulic control of the contaminated groundwater plume would cease. The MPCA has indicated that the recovery system would be shutdown for at least the duration of the project, which is estimated to take five years. It is understood that prior to shutting the groundwater recovery system down, the private well GAC treatment system and bottled water program would be expanded to provide potentially


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impacted residences with a safe water supply in the event the plume migrates further down gradient.

Alternative 2 would include a leachate recirculation system component for the new lined landfill. Leachate recirculation has been proven to be very effective in maximizing waste degradation and decreasing the time frame to achieve waste stabilization. One consequence of leachate recirculation is the increased production of LFG (methane). While the new landfill would also include a LFG recovery system, the design stage provides an ideal opportunity to include additional LFG recovery infrastructure and design considerations in the event LFG to energy (LFGTE) may be considered in the future. It is very likely that LFGTE would be viable at the Washington County Landfill considering the volume of waste in place. Since LFGTE is only discussed for informational purposes, costs or discussions associated with this technology are not included in SEH’s evaluation.



The Dig and Line option would be completed as described in URS’s Alternative 2.

A variance for the liner/groundwater elevation could be obtained. Groundwater recovery and infiltration system would be shut down

during the duration of the project excavation and construction. Private well GAC treatment systems and/or bottled water would be

provided to residences potentially impacted by the potential plume migration associated with shutting down the groundwater recovery and infiltration system.


during waste excavation. LFG gas barrier vent system would be reactivated. Landfill cover materials would be applied to the open portion of the

existing landfill and new landfill at the completion of each day of excavation and placement.

Leachate pumping, treatment, or disposal would not be required during waste excavation.

Leachate hauled offsite from the lined landfill (during routine OMM) would not require treatment to meet WWTP requirements.

Annual OMM effort and costs associated with the new landfill would increase due to increased LFG extraction and leachate management infrastructure and would continue for a 40-year long-term care period.




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URS’s cost detail did not include estimates for engineering and construction oversight; accordingly, these items were estimated by SEH as a percentage of capital costs.

Advantages of this alternative include: Involves contaminant source containment MPCA accepted remediation technology which has proven effective at

other landfill sites Requires minimal ongoing OMM effort compared to onsite groundwater

treatment

Disadvantages include: Labor intensive technology May result in plume migration Increases off site exposure risks Significant on-site exposure risks


This alternative effectively isolates the waste and contaminants from off-site migration within a period of approximately five years. Because the groundwater recovery system would not be in use during waste removal and re-placement, off-site releases through groundwater migration would occur. For a period of 10 years, risks to human health via groundwater ingestion and dermal contact would be addressed for residents receiving GAC treatment or bottled water. This alternative does not account for further down gradient migration of the PFC contaminant plume or additional residents requiring either bottled water or water treatment systems in the long-term. It is assumed that if the contaminant plume migrates beyond the limits predicted in the groundwater model or if protection is needed for a longer time period, that bottled water or the private water treatment system program will be expanded.

Once the waste has been isolated, exposure pathways and routes of exposure through subsurface migration would not exist, thus eliminating the routes of exposure due to ingestion, dermal absorption, and indoor air inhalation of the contaminants of concern at the Washington County Landfill site. This alternative does not eliminate the relatively low risk on or off site due to volatilization of contaminants directly to the ambient air during the landfill construction period, providing an exposure pathway to near-by residential and recreational populations and on-site occupational workers and trespassers.



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Short-term risk associated with excavation includes occupational incidental ingestion and dermal absorption of surface soils, and a significant risk due to incidental ingestion and dermal absorption of subsurface soils and groundwater. Short-term risks also include standard construction hazards including slips, trips, and falls, construction noise, and hazards associated with heavy equipment. Landfill excavation also poses an occupational risk due to potential explosive gases igniting.

3.3.6.2 Compliance with ARARs This alternative would meet the ARARs associated with source control for groundwater protection. Removal of waste and placement in a lined landfill would result in contaminant source control. By removing the waste, contaminant contribution to groundwater should decrease, providing a mechanism to attain ground water quality standards. Since the groundwater recovery system would be shut down during excavation of waste and construction of the new landfill, the potential for contaminant migration would increase. However, residences having the potential to be impacted by an expanded plume would be provided with a private well GAC treatment system.

It is anticipated that the Dig and Line alternative selected would not be in compliance with the five foot separation distance requirement for the new landfill liner and groundwater. However, it is assumed that a variance would be received to permit construction of the liner with less than five feet of separation.

It is assumed the Dig and Line alternative would be designed, installed, operated, and maintained in accordance with applicable State and Federal ARARs. These applicable ARARs would likely be identified during the detailed design stage.

3.3.6.3 Long-Term Effectiveness and Permanence Implementation of this alternative has been proven to be a reliable remedial technology at municipal landfills. Removal of the source and containment using a landfill liner is a very effective method of eliminating ongoing contamination in the long-term. While placement of waste in a lined landfill is determined to be effective and reliable in the long-term, permanence of a landfill liner is uncertain. While relatively low, the risk of landfill liner failure and subsequent environmental impacts exist.

Landfills constructed in compliance with applicable State ARARs have proven effective at managing environmental risks. Continued long term OMM of the new landfill cover, leachate management, and landfill gas control systems would assist in maintenance of long-term effectiveness and permanence.

3.3.6.4 Reduction in Toxicity, Mobility, or Volume Excavation of the waste and placement in a lined landfill would result in reduction of the mobility of contaminants associated with the waste. Since the waste is not destroyed or treated, reduction in toxicity and volume would not be attained. By containing the waste, the volume and toxicity of waste would be managed by engineering controls (i.e., leachate management, LFG recovery and flare). The permanence of containment is dependent on the


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effectiveness of the landfill liner. The Dig and Line alternative is not considered irreversible with regard to containment.

The Dig and Line alternative would not reduce the TMV of contaminants already in groundwater or soils beneath the landfill or in the infiltration basin area. It is assumed the toxicity of contamination within groundwater would reduce via dispersion since the source of contamination is removed and contained.

3.3.6.5 Short-Term Effectiveness Short term human health risk would be increased during implementation of the remedy due to physical hazards and increased potential for exposure to the contaminants. Engineering controls and safety measures would be utilized to limit the potential for increased exposures.

3.3.6.6 Implementability This alternative would likely be implementable due to the landfill’s relatively rural location, compliance with applicable ARARs (with a variance), and following completion, protectiveness of human health and the environment.

All components of this alternative are implementable as services and equipment necessary to install, maintain, and monitor this alternative are readily available. There are no significant concerns regarding constructability, availability, or monitoring.

3.3.6.7 Costs The preliminary projection of initial capital cost for this option is approximately $27,600,000. The preliminary projections of 10-year and 40-year long-term care costs are approximately $60,000 and $150,000 per year, respectively. Long-term 40-year costs include annual routine OMM of the landfill. Long-term 10-year costs include ongoing OMM costs associated with the expanded private well GAC treatment system network.

The 40-year present worth cost is approximately $30,700,000. Cost estimate information for the Dig and Line alternative is provided on Table 2. A detailed cost estimate spreadsheet is provided in Appendix B.

Section 4 – Comparison of Alternatives


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4.0 Comparison of Alternatives Table 1 provides a summary of the evaluation of each alternative against the seven criteria. Table 2 summarizes the evaluation of each alternative with respect to other alternatives, and utilizes a numerical scoring system for each evaluation criteria. The scoring system provides a balanced system to give equal weight to the seven threshold and balancing criteria outlined in 40 CFR Part 300.430(e)(9)(iii)(A-I). Per the MPCA’s request, the State Acceptance and Community Acceptance criteria were not evaluated.

Scoring was based upon each alternative’s relative rating when compared to the other alternatives. A score of 1 to 5 was possible for each criteria. Low scoring indicates the best alternative in the criteria category. The best possible total score is 7 and the worst possible total score is 35.

This section provides a brief discussion of how each alternative compares to the other alternatives identified for detailed evaluation. To reduce the length and redundancy of the discussion, the following conclusions have been made for presenting this comparison of alternatives:

The No Additional Action alternative is not considered appropriate for this site since it does not provide an acceptable level of protection of human health and the environment; nor does it comply with applicable ARARs.

The Force Main Alternative is not considered appropriate for this site since it does not provide an acceptable level of protection of human health and the environment. While the Force Main Alternative would remove PFC contamination from the site and control groundwater plume migration, the recovered PFC contamination is not treated prior to discharge to the MCES, and also not treated at MCES prior to effluent discharge. While not currently applicable since no pre-treatment standards are established, it is anticipated that these standards would be implemented in the future.

Excluding No Additional Action and Force Main, the remedial alternatives include:

Plasma Torch Pump and Treat Dig and Truck Dig and Line

4.1 Overall Protection of Human Health and the Environment

Overall protectiveness of the Plasma Torch, Dig and Truck, and Dig and Line was rated as good with Pump and Treat receiving a rating of fair.

Once the waste has been excavated and either converted to an inert material, removed to an off-site location or placed within a lined on-site facility, exposure pathways will not exist for the Plasma Torch, Dig and Truck, and Dig and Line alternatives.


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While the Pump and Treat alternative provides protection against exposure through gradient control, this alternative does not provide treatment of the source or a barrier against off-site migration through the groundwater. There is also some uncertainty as to the accuracy of the model with regard to prediction of the contaminant plume capture, specifically under changing conditions within the aquifer.

There will likely be some degree of contaminant plume migration during construction of all alternatives presented above when groundwater recovery and landfill gas management systems are shut off. The Pump and Treat alternative does not present this exposure risk during construction, but poses an on-going exposure risk if gradient control is not achieved.

None of the above alternatives address the surface and subsurface soils that may be contaminated in the spray irrigation infiltration basin area. In addition, all alternatives present a short-term occupational risk due to exposure to contaminated waste during construction activities along with standard construction hazards.

4.2 Compliance with ARARs Each of the remedial alternatives provided above would be implemented in compliance with applicable ARARs. Implementation of the Plasma Torch alternative would be more difficult as it is relatively complex and would likely require multiple permits and approvals from the State and local government entities. Accordingly, this alternative received a good rating rather than very good.

The Dig and Truck and Dig and Line alternatives received very good ratings. Both alternatives are relatively complex, but they utilize a well known and acceptable remedial approach. These complex issues are not anticipated to negatively impact compliance with ARARs.

Pump and Treat received a very good rating as this technology has historically operated at the site for VOCs. This alternative includes modification of the treatment component to include removal of PFCs. It is not anticipated that the permit or approval process for this modification would be difficult, as treatability studies have been completed to confirm that compliance with ARARs would be achieved.

4.3 Long-Term Effectiveness and Permanence The long-term effectiveness for Plasma Torch was rated as very good since it involves waste removal and destruction. This approach is irreversible.

The long-term effectiveness for Dig and Truck and Dig and Line were rated as good. A very good rating was not appropriate due to the residual risk associated with potential landfill liner failure. It is assumed that by removing waste and placing it in an engineered and approved lined system, elimination of TMV is attained, thereby resulting in plume dispersion. However, the effectiveness of the liner system and GAC treatment are reliant on independent requirements being maintained.


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Pump and Treat was rated fair for long-term effectiveness. This alternative would be effective assuming groundwater models predicting capture requirements are accurate and the aquifer does not experience changes which may affect the predictions. Pump and treat does not provide source (waste) containment or control to prevent ongoing impacts to the groundwater.

4.4 Reduction of Toxicity, Mobility, or Volume The reduction of TMV using the Plasma Torch, Dig and Truck, and Dig and Line alternatives is rated as very good. The Plasma Torch alternative involves removal and destruction of the source and utilizes GAC treatment at potentially affected private wells to remove contaminants already in the groundwater. The Dig and Truck and Dig and Line alternatives also include source removal, but achieve TMV reduction via containment using an engineered landfill (liner, cover, LFG extraction, leachate management, and surface water management) and GAC private well treatment systems.

The Pump and Treat alternative was ranked as fair for reduction of TMV. Pump and Treat would provide reduction of TMV for contaminants in recovered groundwater, but would not address the source or its long-term contribution to the groundwater. The existing LFG recovery system would provide reduction of TMV for the volatile components in the source, but would provide minimal TMV reduction for the PFC constituents, particularly those existing in a saturated environment.

4.5 Short-Term Effectiveness The short-term effectiveness for the Plasma Torch, Dig and Truck, and Dig and Line alternatives is rated as fair due to the overall increase of risk to human health and the environment during their respective implementation. Each alternative involves extensive exposure to waste and relatively long-term exposure to construction hazards. In addition, the Dig and Truck alternative would increase off-site exposure risks associated with off-site trucking of waste. The Dig and Line alternative involves stock piling of waste materials onsite for an extended period, thereby increasing exposure risks to onsite personnel and potentially to the off-site general public. The plasma torch alternative utilizes extremely high electric voltage, thereby increasing the potential for electrocution.

The Pump and Treat alternative was ranked as good for short-term effectiveness. With exception of landfill cover replacement, exposures to risks associated with its implementation would be minimal.

4.6 Implementability It is assumed that each of the alternatives presented for this discussion would be implementable as each provides protection of human health and the environment and each would be completed in compliance with applicable ARARs. It has been determined that the materials and equipment required to implement each alternative are readily available. Accordingly, the Plasma Torch, Dig and Truck, Dig and Line, and Pump and Treat alternatives are ranked as good for implementability.


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4.7 Cost Total project costs, as presented as present net worth, ranges from approximately $193,000,000 (Plasma Torch) to approximately $17,500,000 (Pump and Treat). Present net worth is based on a 40-year long-term care period using a 5% discount rate.

As shown on the Preliminary Engineer Cost Projection spreadsheets for each alternative (included as Appendix B), several of the alternatives include a 10-year and 40-year long-term OMM estimate. The 10-year and 40-year long-term OMM estimates were calculated independently then combined to determine net present worth.

Pump and Treat is the least expensive alternative that has been determined to be implementable, and is rated as good. Capital investment for this alternative is mainly attributable to replacement of the landfill cover and purchase of the groundwater GAC treatment system. The largest portion of the present net worth cost is associated with long-term OMM of the groundwater GAC treatment system.

Plasma Torch is rated as very poor for costs due to the large capital investment for equipment purchase and electricity demands necessary to implement this technology. Estimates of electricity usage costs and OMM for the Plasma Torch system are provided as capital costs since it is estimated that they would be incurred for less than 5-years.

The Dig and Truck alternative is rated as poor for cost due to the high capital costs necessary to transport and dispose of the excavated waste at an off-site landfill. The Dig and Line alternative is rated as fair due to the lower costs, when compared to Dig and Truck, associated with placing waste on-site in an engineered landfill.

Section 5 – Remedy Feasibility Assessment Summary


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5.0 Remedy Feasibility Assessment Summary Based on the results of the analyses prepared by others and presented herein, feasible alternatives for remediation of VOC- and PFC-impacted groundwater emanating from the Washington County Landfill have been identified.

SEH developed a ranking method to allow comparison of one alternative against another within each of the seven EPA comparative criteria described above. The ranking method provided a balanced system to give equal weight to the seven criteria. The scoring was based upon each alternative’s relative rating when compared to the other alternatives. Based on the results of the analyses, the relative ranking of the six remedial options follows (lowest score is considered the best):

Option Total Score No Additional Action 27 Plasma Torch 18 Force Main 20 Pump and Treat 16 Dig and Truck 15 Dig and Line 14

Dig and Line appears to be the most feasible remedial action option, followed closely by the Dig and Truck option and Pump and Treat option.

Additional evaluation, including but not limited to consideration of the agency acceptance and public acceptance criteria that were not evaluated by SEH, may be required prior to selection of a final remedy. Once a final remedy is selected, design studies should be conducted or refined to further define the cost, approach, permit requirements and schedule.

Each remedial option has been reviewed and presented as a conceptual approach and costs presented are believed to be conservative. It was not within the scope of this report to present a detailed design approach or estimate of costs or schedule.

Numerous assumptions have been made to support identification and evaluation of potential remedial action options as well as their associated costs. The assumptions result in commensurate uncertainty in the information and estimates provided. SEH has utilized published guidance documents, our experience at other similar sites, our experience utilizing these technologies, and industry accepted cost estimating practices to try to minimize the uncertainty resulting from the following, at a minimum:

Detailed remedial action option designs have not been completed. Implementation of a remedy would not likely commence for several

years and may take several years to complete. Regulatory and community acceptance of the potential remedial action

options presented has not been evaluated herein but is assumed. None of the remedial options address contamination that may be present

in the spray irrigation infiltration area.


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Recently published MGS information regarding geological conditions in the area of the Washington County Landfill suggest potential uncertainty regarding the groundwater assumptions and therefore, the model results used to predict hydraulic control at the site.

Section 6 – Standard of Care


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6.0 Standard of Care SEH’s opinions of probable costs provided herein are made on the basis of SEH’s experience and qualifications and represent SEH’s best judgment as a professional generally familiar with the industry. However, as additional information may become available that may change SEH’s assumptions made herein and since SEH has no control over the cost of labor, materials, equipment or services furnished by others, or over any contractor’s methods of determining prices, or over competitive bidding or market conditions, SEH cannot and does not guarantee that proposals, bids or actual remedy cost would not vary from opinions of probable cost prepared by SEH.

The conclusions and recommendations contained in this report were arrived at in accordance with generally accepted professional engineering practice at this time and location. Other than this, no warranty is implied or intended.

Section 7 – References and Resources


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7.0 References and Resources Air Force Center for Environmental Excellence - Technology Transfer

Division, 1999. Decision Tool for Landfill Remediation, prepared by Mitretek Systems.

ATSDR, 2006. ToxFAQx for Vinyl Chloride. Agency for Toxic Substances & Disease Registry, August 2007. http://www.atsdr.cdc.gov/tfacts20.html

ATSDR, 2007. ToxFAQx for Benzene. Agency for Toxic Substances & Disease Registry, August 2007. http://www.atsdr.cdc.gov/tfacts3.html

Austin, 1972. Austin, G.S . 1972, Paleozoic Lithostratigraphy of Southeastern Minnesota; Geology of Minnesota – A Centennial Volume, p.459-471.

Barr, 2005. Washington County Landfill Feasibility Study Report, June 29, 2005. Prepared by Barr.

Behar, March 2007. The Prophet of Garbage, Popular Science, p.56.

CRA, August 30, 2007a. Appendix B, Column Tests to Develop Breakthrough Curves for Ion Exchange Resins and Activated Carbon, August 30, 2007. Appendix to letter report “Conceptual Design of a Groundwater Treatment System Washington County Closed Landfill, Lake Elmo, Minnesota, March 19, 2007.

CRA, August 30, 2007b. Appendix D, Revised Cost Estimate for the Groundwater Treatment System at the Washington County Landfill, August 30, 2007. Appendix to letter report “Conceptual Design of a Groundwater Treatment System Washington County Closed Landfill, Lake Elmo, Minnesota, March 19, 2007.

CRA, September 14, 2007. Appendix E, Column Adsorption Tests with Activated Carbon at pH 3, September 14, 2007. Appendix to letter report “Conceptual Design of a Groundwater Treatment System Washington County Closed Landfill, Lake Elmo, Minnesota, March 19, 2007.

Howard, 2007. Telephone conversation between Mr. John Howard (Coronal Plasma Gas Solutions) and Mr. Brian Kent on October 30, 2007.

MDH, 2007a. Environmental Health Information, Perfluorochemicals and Health, August, 2007. Minnesota Department of health, Division of Environmental Health, Site Assessment and Consultation Unit.

MDH, 2007b. Health Risk Limits for Perfluorochemicals, Report to the Minnesota Legislature 2007, Interim report, September 30, 2007. Minnesota Department of Health.

MDH HRL, 2007. Minnesota Department of Health Health Risk Limits website on 10-24-07. http://www.health.state.mn.us/divs/eh/groundwater/hrltable.html


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MGS, 2007. The Lake Elmo Downhole Logging Project: Hydrostratigraphic Characterization of Fractured Bedrock at a Perfluorochemical Contamination Site. Minnesota Geological Survey, November 1, 2007. Anthony C. Runkel, John Mossler, Rober Tipping.

MPCA, 2006. Investigation of Perfluorochemical (PFC) Contamination in Minnesota Phase One, Report to Senate Environment Committee.

MPCA, 2007. Minnesota Pollution Control Agency, Closed landfill Program, April 12, 2007. Washington County Sanitary Landfill Annual Report 2006.

Sittig, 1991. Sittig, Marshall, Princeton University (retired), 1991. Handbook of Toxic and Hazardous Chemicals and Carcinogens, Third Edition. Volume 1, Benzene, pg 207-210. Volume 2, Vinyl chloride, pg 1643-1645. Noyes Publications, Park Ridge, New Jersey.

United States Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, 2005, Health Consultation, 3M Chemolite, Perfluorochemical Releases at the 3M Cottage Grove Facility, EPA FID: MND006172969.

URS, June 2007a. Washington County Landfill Sanitary Forcemain Phase II – Preparation of Feasibility-level Cost Estimates, June 22, 2007. URS Corporation memorandum to Shawn Ruotsinoja, MPCA.

URS, August 2007b. 50% Conceptual Design, August 20, 2007. URS Corporation memorandum to Shawn Ruotsinoja, MPCA.

USEPA, 1988. USEPA, Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA (Interim Final) EPA/540/G-89/004, Office of Emergency and Remedial Response, Washington, D.C.

USEPA, 1990. The Feasibility Study: Detailed Analysis of Remedial Alternatives, Directive No.: 9355.3-01FS4, Office of Emergency and Remedial Response, Washington, D.C.

USEPA, 1990, Final Guidance on Administrative Records for Selecting CERCLA Response Actions, OSWER Directive: 9833.3A-1, Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 1991a. Conducting Remedial Investigations/ Feasibility Studies for CERCLA Municipal Landfill Sites EPA/540/P-91/001, USEPA, Office of Emergency and Remedial Response, Washington, D.C.

USEPA, 1991b. Risk Assessment Guidance for Superfund (RAGS): Volume 1 - Human Health Evaluation Manual, Part C, Risk Evaluation of Remedial Alternatives (Interim), December 1991, USEPA Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 1993, Presumptive Remedies: Site Characterization and Technology Selection for CERCLA Site with Volatile Organic Compounds in Soils, PB 93-963346, Office of Emergency and Remedial Response, Washington, D.C.


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USEPA, 1993, Presumptive Remedy for CERCLA Municipal Landfill Sites, EPA 540-F-93-035, Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 1994, Feasibility Study Analysis for CERCLA Municipal Landfill Sites, EPA 540-R-94/081.

USEPA, 1996, The Role of Cost in the Superfund Remedy Selection Process, EPA 540-F-96/018, Office of Emergency and Remedial Response, Washington, D.C.

USEPA, 1997, Landfill Presumptive Remedy Saves Time and Cost, EPA 540-F-96-017, Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 1999, Reuse of CERCLA Landfill and Containment Sites, EPA 540-F-99-015, Office of Emergency and Remedial Response, Washington, D.C.

USEPA, July 2000, A Guide to Developing and Documenting Cost Estimates During the Feasibility Study, EPA 540-R-00-002, Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 2002, Groundwater Remedies Selected at Superfund Sites, EPA 542-R-01-022, Office of Solid Waste and Emergency Response, Washington, D.C.

USEPA, 2004. Third Five-Year Review Report for Washington County Landfill, Lake Elmo, Washington County, Minnesota, April 2004. USEPA – Region 5.

USEPA, 2005, Draft Risk Assessment of the Potential Human Health Effects Associated with Exposure to Perfluorooctanoic Acid and Its Salts, Office of Pollution Prevention and Toxics Risk Assessment Division.

USEPA IRIS, 2007a. Integrated Risk Information System website on 11-5-07, Benzene (CASRN 71-43-2) http://www.epa.gov./iris/subst/0276.htm.

USEPA IRIS, 2007b. Integrated Risk Information System website on 11-5-07, Vinyl chloride (CASRN 75-01-4) http://www.epa.gov./iris/subst/0276.htm.

Veolia, 2007. e-mail correspondence between Mr. Kris Gunderson (Veolia) and Mr. Brian Kent on October 26, 2007.

Tables Table 1 – Summary of Criteria Evaluation

Table 2 – Comparison of Remedial Action Alternatives

Washington County Landfill A-MNPCA0802.00 Lake Elmo, Minnesota

Table 1 Summary of Criteria Evaluation

Criteria No Additional Action Plasma Torch Pump and Treat (Force Main) Pump and Treat On-site Dig and Truck Dig and Line Overall Protection of Human Health and Environment

-New cover system reduces infiltration through the waste -Air stripping removes VOCs but will not remove PFCs -Infiltration on-site may drive contaminants more rapidly off site

-Source removal and destruction removes potential for further groundwater impacts -Emissions from the facility purported to be safe

-Groundwater gradient control prevents migration of contaminants off-site to receptors -Potential for releases if pumps fail

-Groundwater gradient control prevents migration of contaminants off-site to receptors -Potential for releases if pumps fail

-Source removal and disposal off-site removes potential for further groundwater impacts at this site -Potential for releases from new disposal site

-Source excavation and disposal in lined facility on site reduces potential for further groundwater impacts at this site -Potential for releases from new disposal cell

Compliance with potential ARARs and TBCs

-Not in compliance with ARARs for groundwater with respect to PFC HRLs -Potential NPDES discharge issues

-In compliance with ARARs for source control with respect to VOCs and PFCs -Air Permits required for construction and operation -Electrical usage requirements may exceed supply -Groundwater which has escaped the site will not be captured and contaminants will migrate until dispersed -Ambient Air/Odor Control during excavation

-In compliance with ARARs for source control with respect to PFC -Groundwater which has escaped the site will not be captured and contaminants will migrate until dispersed -MCES discharge permit -Future pretreatment standards -City of Oakdale sanitary sewer connection requirements

-In compliance with ARARs for source control with respect to PFC -Groundwater which has escaped the site will not be captured and contaminants will migrate until dispersed

-In compliance with ARARs for source control with respect to PFC -Groundwater which has escaped the site will not be captured and contaminants will migrate until dispersed -Waste designation qualifies as Industrial Waste? -Traffic control plans -Road weight restrictions -Ambient Air/Odor Control during excavation

-In compliance with ARARs for source control with respect to PFC -Groundwater which has escaped the site will not be captured and contaminants will migrate until dispersed -Ambient Air/Odor Control

Long Term Effectiveness -Magnitude of Residual Risk -Risk to groundwater will remain

-New cap will limit infiltration -Waste in groundwater will continue to leach contaminants -PFC contaminants in discharge area may remain as long term source

-Complete destruction removes potential for future exposure -PFC contaminants in discharge area may remain as long term source

-Source remains at site -PFC contaminants in discharge area will remain as long term source

-Source remains at site -PFC contaminants in discharge area will remain as long term source

-Relocation of waste transfers potential risk to a new location/facility -Risk at disposal site is minimized due to current liner requirements -Potential leachate disposal issues at disposal facility -Potential for releases from disposal facility -PFC contaminants in discharge area may remain as long term source

-Source remains at site -Entombment of waste reduces potential risk; risk is minimized due to current liner requirements -PFC contaminants in discharge area will remain as long term source

-Adequacy and Reliability of Controls

-Treatment and hydraulic control is inadequate for PFCs in groundwater -Does not protect occupational exposure at surface or subsurface

-Greatest long-term effectiveness -Groundwater gradient control may not prevent off-site migration -New cap will limit infiltration; however waste may remain in groundwater

-Groundwater gradient control may not prevent off-site migration -New cap will limit infiltration, however waste may remain in groundwater

-Control is adequate for the site -Potential for future releases due to liner failure -Control is adequate for the site


Table 1 (Continued) Summary of Criteria Evaluation

Criteria No Additional Action Plasma Torch Pump and Treat (Force Main) Pump and Treat On-site Dig and Truck Dig and Line Reduction of Toxicity, Mobility and Volume

-Treatment process used and materials treated

-No treatment of PFC, volatilization of VOCs to the atmosphere

-Destruction of waste and source of contamination

-Groundwater treatment at WWTP limits future impacts at the site

-Groundwater treatment limits future impacts

-No treatment proposed, alternative involves relocation of waste source

-No treatment proposed, alternative involves entombment of waste source

-Amount of Hazardous Materials Destroyed or Treated

-No PFCs treated or destroyed -VOCs in groundwater treated by volatilization

-PFCs and VOCs in waste destroyed

-No PFCs destroyed, pass-through to WWTP possible relocation of contamination

-PFCs captured and contained -VOCs in groundwater treated by volatilization

-No treatment or destruction of contamination source

-No treatment or destruction of contamination source

-Expected Reduction in Toxicity, Mobility and Volume

-No reduction of TMV for PFCs -Maximum reduction of TMV -Impacts to groundwater are reduced -Volume of contamination source not reduced

-Impacts to groundwater are reduced -Volume of contamination source not reduce

-Reduction in TMV at this site due to disposal in lined facility offsite

-Reduction in mobility by placing in lined facility -No reduction in toxicity and volume

-Irreversibility of the Treatment -Treatment for PFCs not included in this alternative

-Irreversible, contamination source destroyed

-Groundwater treatment may be reversible

-Groundwater treatment may be reversible

-Treatment not included in this alternative Effect of implementation of alternative is irreversible at this site

-Treatment not included in this alternative -Effect of implementation of alternative may be reversible at this site

-Type and Quantity of Treatment Residual

-Treatment not included in this alternative

-Residual slag assumed inert -Maximum volume reduction of residual

-No treatment on site, no treatment residual

-Groundwater GAC media will need to be disposed of

-All waste relocated to a new facility

-All waste placed in new lined cell on site

Short Term Effectiveness -Protection of Community during remedial actions

-Not effective in short term for PFCs

-Not effective in short term for PFC

-Effective in short term for PFC containment -Potential releases from force main

-Effective in short term for PFC containment

-Not effective in short term for PFC -Off-site exposure due to releases during trucking

-Not effective in short term for PFC

-Protection of workers during remedial actions

-Workers could come in contact with PFCs contaminated soils and water -Construction hazards with cap -Migration of contaminants to ambient air during construction of cap

-Workers could come in contact with VOC and PFC contaminated soils and water -Construction hazards -Migration of LFG to ambient air during excavation -Explosion hazard

-Exposure to PFC and waste minimized -Construction hazards -Confined space hazard -Migration of contaminants to ambient air during construction of cap

-Exposure to PFC and waste minimized -Construction hazards -Migration of contaminants to ambient air during construction of cap

-Workers could come in contact with VOC and PFC contaminated soils and water -Excavation hazard -Explosion hazard -Construction hazards

-Workers could come in contact with PFCs contaminated soils and water -Excavation hazard -Explosion hazard -Construction hazards

-Environmental Impacts -On-going impacts of PFCs in groundwater

-On-going impacts of PFCs in groundwater, increased groundwater impacts by VOCs -Increased fugitive emissions -

-Environmental impacts down gradient of the site are minimized -Potential impacts at WWTP outfall

-Environmental impacts down gradient of the site are minimized

-On-going impacts of PFCs in groundwater, increased groundwater impacts by VOCs -Increased fugitive emissions

-On-going impacts of PFCs in groundwater, increased groundwater impacts by VOCs -Increased fugitive emissions

-Time until Remedial Action Objectives are achieved

-Remedial action objectives for PFCs in groundwater are not achieved

-Source destruction in 35 years Groundwater PFCs dispersed over time

-Containment of groundwater on site in 2 – 3 years -Effective in short term for -Groundwater PFCs dispersed over time

-Containment of groundwater on site in less than 1 year -Groundwater PFCs dispersed over time

-Source removal in approximately 2 years -Groundwater PFCs dispersed over time

-Containment of source in five years -Groundwater PFCs dispersed over time



Criteria No Additional Action Plasma Torch Pump and Treat (Force Main) Pump and Treat On-site Dig and Truck Dig and Line Implementability -Technical Feasibility -Technically feasible -Emerging technology,

technically feasible, but comparably-sized systems are not currently operating

-Technically feasible -Technically feasible -Technically feasible -Technically feasible

-Ability to construct and operate technology

System is already in place and operating

-Constructable, but operational uncertainties exist

-Alternative utilizes proven technology that is readily available

-Alternative utilizes proven technology that is readily available

-Alternative involves excavation and trucking services which are readily available

-Alternative involves excavation and trucking services which are readily available

-Reliability of technology -Not reliable for PFCs -Emerging technology -Reliable and proven for VOCs, unreliable for PFCs

-Reliable and proven based on bench scale testing

-Reliable and proven -Reliable and proven

-Ability to monitor effectiveness of remedy

-Plume expansion will not be monitored

-Waste destruction can be monitored -Air emissions and waste characteristics can be monitored

-Groundwater and effluent quality can easily be monitored

-Groundwater and effluent quality can easily be monitored

-Waste relocation can be easily monitored

-Waste relocation can be easily monitored

-Ease of undertaking additional remedial action, if any

See other options -See other options -See other options -See other options -See other options -See other options

-Availability of Services and Materials

-Materials and services are readily available

-Materials and services are specialized and may not be readily available





-Administered Feasibility –Ability to coordinate and obtain approval from other agencies

-MPCA controls the site -No additional approvals are required

-New facility will require a permit to be issued by the MPCA

-MPCA has regulatory and operational control of the site so no additional approvals are required on site -Disposal permit may be required by MCES

-MPCA has regulatory and operational control of the site so no additional approvals are required on site

-MPCA has regulatory and operational control of the site so no additional approvals are required on site -Disposal site approval required

-MPCA has regulatory and operational control of the site so no additional approvals are required on site



Criteria No Additional Action Plasma Torch Pump and Treat (Force Main) Pump and Treat On-site Dig and Truck Dig and Line Cost Capital Cost $5,000,000 $192,300,000 $7,300,000 $5,800,000 $66,800,000 $27,600,000 Annual Operating and Maintenance Costs (40 years) (10 years)

$120,000

$87,000

$419,000 $30,000

$668,000 $30,000

$87,000

$150,000 $60,000

Present Worth Cost

$7,100,000

$193,000,000

$14,800,000

$17,500,000

$67,500,000

$30,700,000

Table 2Comparison of Remedial Action Alternatives

No Additional Action Plasma Torch Force Main Pump and Treat Dig and Truck Dig and Line

*Rating **Score *Rating **Score *Rating **Score *Rating **Score *Rating **Score *Rating **Score

Overall Protection of Human Health and the Environment Very Poor 5 Good 2 Fair 3 Fair 3 Good 2 Good 2Compliance with ARARs Very Poor 5 Good 2 Fair 3 Very Good 1 Very Good 1 Very Good 1

BalancingLong-Term Effectiveness and Permanence Very Poor 5 Very Good 1 Fair 3 Fair 3 Good 2 Good 2

Reduction of TMV Through Treatment Very Poor 5 Very Good 1 Poor 4 Fair 3 Very Good 1 Very Good 1

Short-Term Effectiveness Fair 3 Fair 3 Fair 3 Good 2 Fair 3 Fair 3

Implementability Fair 3 Poor 4 Good 2 Good 2 Good 2 Good 2

Approximate Initial Capital $5,000,000 $192,300,000 $7,300,000 $5,800,000 $66,800,000 $27,600,000

Cost Annual OMM $120,000 $87,000 $450,000 $700,000 $87,000 $210,000

Net Present Worth $7,100,000 $193,000,000 $14,800,000 $17,500,000 $67,500,000 $30,700,000

27 18 20 16 15 14* Rating System: Ratings (Very Poor, Poor, Fair, Good, Very Good) for specific evaluation criteria take into account several factors as required in 40 CFR Part 300.430(e)(9)(iii)(A-I)**Scoring System: 1 = best rating for specific evaluation criteria, 5 = worst rating for specific evaluation criteria.***The lowest total score is considered the best score, and therefore may be the best option. 7 is lowest possible total score. 35 is highest possible total score.Compiled by: BLK Checked by: BKO

5 2 2 4 31

***Total Score:

Remedial Action Alternatives:

Evaluation CriteriaThreshold

Washington County LandfillLake Elmo, Minnesota A-MNPCA0802.00

Figures Figure 1 – Pictorial CSM

Figure 2 – Fate and Transport Flow CSM

Figure 3 – Site Location Map

Figure 4 – Bedrock Geology

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(Y:\KO\M\MNPCA\080200/DraftReport\Figure1.pdf)

FILE NO.

A-AMNPCA0802.00

DATE 11/14/2007

SITE LOCATION MAP WASHINGTON COUNTY LANDFILL

LAKE ELMO, MINNESOTA

Figure 3

Source: Washington County

Landfill Feasibility Study Report, Barr Engineering Co., June 29,

2005

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FILE NO.

A-MNPCA0802.00

DATE 11/14/2007

Source: Washington County Landfill and Former Oakdale

Disposal Site Groundwater Flow and Solute Transport Modeling,

Barr Engineering Co., December 19, 2005

Figure 4

BEDROCK GEOLOGY WASHINGTON COUNTY LANDFILL

LAKE ELMO, MINNESOTA

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Appendix A Remedy Ranking Criteria

Appendix B Preliminary Engineers Cost Projections

Project Description: Washington County LandfillProject Location: Lake ElmoSEH# MNPCA0802.00

Capital CostsItemNew LFG Cover 5,000,000$

Subtotal: 5,000,000$ Contingency 0% -$ Subtotal: 5,000,000$ Planning and Permitting 0% -$ Engineering 0% -$ Construction Oversight 0% -$ Subtotal:Total Initial Capital Costs: 5,000,000$

Long Term Annual CostsItemAnnual Operations, Maintenance, and Monitoring Costs:GAC/Bottled Water (40 year LTC) 30,000$ Routine OMM (40 year LTC) 90,000$ Subtotal: 120,000$ Contingency 0% -$ Total Annual OM&M Costs: 120,000$

Present Worth Costs:Routine OMM GAC Private Well OMMLong Term Operation Period, n (years) 40 years Long Term Operation Period, n (years) 40 yearsAverage Net Interest Rate, i 5% Average Net Interest Rate, i 5%Present Worth Factor (i, n) 17.159 Present Worth Factor (i, n) 17.159Annual OM&M Costs (40 years): 90,000$

Annual OM&M Costs (40 years) 30,000$ Present Worth Long Term OM&M Costs 1,544,318$ Present Worth Long Term OM&M Costs (40 years) 514,773$ Initial Capital Costs: 5,000,000$ Present Worth Total Costs: 7,059,090$

DetailsCapital CostsItemNew LF Cap Quantity Unit Unit Price Total Price

1 LS 5,000,000$ 5,000,000$

Total 5,000,000$ Long Term Annual CostsItem Quantity Unit Unit Price Total PriceGAC/Bottled Water 1 ls 30,000$ 30,000$ Routine OMM 1 ls 90,000$ 90,000$

Total 120,000$

ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue LF cover costs based on Washington County Landfill Alternative Selection Matrix - Cost provided by MNPCAPrivate well GAC treatment system requirement extended to 40 years since groundwater is not contained or source is not removed

Preliminary Engineer's Cost Projection- No Additional Action


Capital CostsItemPlasma Torch 28,000,000$ Site Preparation 2,283,083$ Waste Excavation/Load into Plasma Torch 8,750,000$

Subtotal: 39,033,083$ Contingency 21% 8,196,947$ Detailed EngineeringEngineering 2% 780,662$ Engineering/Construction Oversight 2% 780,662$ Subtotal: 9,758,271$ Expand GAC/Bottled Water Coverage 307,998$ Plasma Torch OMM (assume 3.5 years) 5,250,000$ Electric Usage (assume 3.5 years) 137,970,000$

Total Initial Capital Costs: 192,319,351$

Long Term Annual CostsItemOMMAnnual Routine LF OMM (assumed 10 year LTC) 27,000$ PW GAC/Bottled Water (assumed 10 year LTC) 60,000$

Subtotal: 87,000$ Contingency 0% -$ Total Annual OM&M Costs: 87,000$

Present Worth Costs:GAC Private Well OMM/Limited LF OMMLong Term Operation Period, n (years) 10 yearsAverage Net Interest Rate, i 5%Present Worth Factor (i, n) 7.722Annual OM&M Costs (10 years) 87,000$

Present Worth Long Term OM&M Costs (10 years) 671,791$

Initial Capital Costs: 192,319,351$ Present Worth Total Costs: 192,991,142$

DetailsCapital CostsItemPlasma Torch Quantity Unit Unit Price Total PriceTorch (2000 ton/day cabability) 40 Each 400,000$ 16,000,000$ Vessels(2000 ton/day cabability) 10 Each 1,200,000$ 12,000,000$

Subtotal 28,000,000$

Site Preparation/Restoration Quantity Unit Unit Price Total PriceMobilization/Bond 1 LS 1,200,000$ 1,200,000$ Temporary Construction Facilities and Utilities 1 LS 20,000$ 20,000$ Demolition and Removals 1 LS 15,000$ 15,000$ Stockpile Existing Cover Material 145050 CY 2.50$ 362,625$ Temp Access Roads 8361 LF 20$ 167,220$ Re-place and Grade Cover Material 145050 CY 2.50$ 362,625$ Restoration and Seeding 57.4 AC 1,200$ 68,880$ 6" Topsoil Outside Limits of Final Cover 16133 CY 2.50$ 40,333$ Install Perimeter Fencing 3450 LF 12$ 41,400$ Site Cleanup and Demob 1 LS 5,000$ 5,000$

Subtotal 2,283,083$

Waste Excavation/Load into Plasma Torch Quantity Unit Unit Price Total PriceExcavation (2.5M yd3=2.5M Ton) 2,500,000 Ton 3.50$ 8,750,000$

Subtotal 8,750,000$

Expand GAC/Bottled Water Coverage Quantity Unit Unit Price Total PriceGAC Units 213 Each 1446 307,998$

Subtotal 307,998$

Total 39,341,081$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceAnnual Routine LF OMM 1 LS 27,000$ 27,000$ PW GAC/Bottled Water 1 LS 60,000$ 60,000$ Annual Plasma Torch OMM 3.5 LS 1,500,000$ 5,250,000$ Annual Electric Usage 1839600 MWhr 75$ 137,970,000$

Subtotal 143,307,000$ Total 143,307,000$

ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue Assumed that long-term routine OMM effort would require approximately 30% existing effort and be terminated within 10 years of waste excavationOMM effort associated with GAC/Bottled Water from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assumes groundwater pumping system would be shut down to eliminate groundwater mound. As a result, the GAC treatment network would be expanded to account for likely expansion of contaminant plumeOMM costs associated with expanded GAC/Bottled Water program from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Cost Estimate does not include Health and Safety Monitoring/SamplingAssume 2,500,000 cubic yards of waste materail in placeAssume weight of excavated waste at 1 ton per cubic yard (2000 lb/yd3)Cost detail for Plasma Torch based on estimates provided by Coronal, LLC. The estimates are intended for budgetary purposes and is sized for 2000 tons/day of waste materials.Cost details based on assumption that 2000 tons/day of waste material would be direct into loaded Plasma Torch. Equipment associated with this effort includes 2 excavators, 1 dozer, and one project manager.Restoration effort assumes only stockpiled cover soils would be used and excavation would not be completely backfilled. No borrow source is assumedAssume energy recovery type system not desired 4 Plasma torches and one vessel required for each 200 ton/day destruction requirement. One Torch =$400,000; One vessel = $1,200,000 (does not include energy recovery via gasification)Maximum power use for one torch =1.5 MW; assumed one kW hr=$0.07540 Plasma Torches max power use= 60 MWhrAnnual OMM effort for 2000 ton/day plasma torch system approximately $1,500,00020% contingency due to lack of operation and performance data for plasma technology and possible high costs to provide suitable electric sourceOMM and electrical use for plasma torch assumed to occur for 3.5-years and considered as capital costCosts associated with daily cover requirements (Minnesota ARAR) included with contingency costsCosts associated with health and safety sampling and monitoring included with contingency costs

Preliminary Engineer's Cost Projection- Plasma Torch


Capital CostsItemOpen Cut Construction 1,283,261$ Lift Station 169,410$

Subtotal: 1,452,671$ Contingency 20% 290,534$ Detailed Engineering/Permits 10% 145,267$ Engineering/Construction Oversight 10% 145,267$ Start up 3% 43,580$ Subtotal: 581,068$ Sewer Access Charge (One time fee) 302,200$ New LF Cap 5,000,000$ Subtotal: 5,302,200$ Total Initial Capital Costs: 7,335,939$

Long Term Annual CostsItemOMMAnnual Routine LF OMM (assumed 40 year LTC) 90,000$ Groundwater recovery OMM (assumes 40 years operation) 50,000$ Annual Long Term Lift Station and Forcemain OMM (assumed 40 year LTC) 53,800$ PW GAC/Bottled Water (assumed 10 year LTC) 30,000$ Annual Sanitary Usage Costs (assumed 40 year LTC) 174,079$ Annual MCES Add-on Service Charge (assumed 40 year LTC) 50,773$


Present Worth Costs:Routine OMM GAC Private Well OMMLong Term Operation Period, n (years) 40 years Long Term Operation Period, n (years) 10 yearsAverage Net Interest Rate, i 5% Average Net Interest Rate, i 5%Present Worth Factor (i, n) 17.159 Present Worth Factor (i, n) 7.722Annual OM&M Costs (40 years) 418,652$

Annual OM&M Costs (10 years) 30,000$ Present Worth Long Term OM&M Costs (40 years) 7,183,680$

Present Worth Long Term OM&M Costs (10 years) 231,652$ Initial Capital Costs: 7,335,939$ Present Worth Total Costs: 14,751,272$

DetailsCapital Costs (URS, June 22, 2007)ItemOpen Cut Construction Quantity Unit Unit Price Total PriceMobilization 1 LS 70,000$ 70,000$ Admin costs 5 Month 500$ 2,500$ Protection of Environment 1 LS 2,000$ 2,000$ Clearing 10 Tree 200$ 2,000$ Grubbing 10 Tree 200$ 2,000$ Test Pitting 16 Hour 100$ 1,600$ Remove Metal Culverts 288 LF 10$ 2,880$ Remove Metal Aprons 6 Each 20$ 120$ Remove Curb and Gutter 670 LF 5$ 3,350$ Remove Bit. Pavement 191 SY 5$ 955$ Remove Bit. Driveway Pavement 149 SY 5$ 745$ Remove Concrete Sidewalk 27 SY 5$ 135$ Saw Bit. Pavement 251 LF 5$ 1,255$ Saw Conc. Pavement 15 LF 10$ 150$ Street Sweeper 40 Hour 100$ 4,000$ Salvage Hydrant 1 Each 700$ 700$ Salvate Gate Valve and Box 1 Each 500$ 500$ Salvage Mail Box Support 13 Each 200$ 2,600$ Salvage Sign 3 Each 400$ 1,200$ Salvage Chain Link Fence 40 LF 5$ 200$ Install Salvaged Hydrant 1 Each 3,000$ 3,000$ Install Salvaged Gate Valve and Box 1 Each 1,000$ 1,000$ Install Salvaged Mail Box Support 13 Each 150$ 1,950$ Install Salvaged Chain Link Fence 40 LF 5$ 200$ Install Salvaged Sign 3 Each 300$ 900$ Agg. Base Class 5 57 CY 20$ 1,140$ Bit. Patch 92 Ton 60$ 5,520$ Bit. Tack Coat 18 Gal 1$ 18$ Conc. Curb and Gutter Design D412 629 LF 15$ 9,435$ Conc. Curb and Gutter Design B618 41 LF 20$ 820$ Concrete Sidewalk 250 SF 5$ 1,250$ 21" CMP Culvert 208 LF 30$ 6,240$ 21" CMP Apron 2 Each 150$ 300$ 24" CMP Culvert 80 LF 40$ 3,200$ 24" CMP Culvert 4 Each 200$ 800$ Connect to Existing San. Sewer 1 Each 1,500$ 1,500$ Air Relief Manhole 1 Each 6,000$ 6,000$ Gate Valve Manhole 2 Each 4,000$ 8,000$ 18" Steel Casing Pipe (jacked) 1270 LF 200$ 254,000$ 4" HDPE San. Sewer 80 LF 42$ 3,360$ 6" HDPE San. Sewer 17248 LF 44$ 758,912$ 4" HDPE San. Sewer Cleanout 2 Each 2,300$ 4,600$ 6" HDPE San. Sewer Cleanout 19 Each 2,500$ 47,500$ 4" Gate Valve Box 2 Each 1,000$ 2,000$ Traffic Control 1 LS 10,000$ 10,000$ Transplant Tree 80 Tree 400$ 32,000$ Silt Fence, Type Machine Sliced 2720 LF 3$ 8,160$ Seeding 7 Acre 300$ 2,100$ Sodding Type Lawn 2322 SY 3$ 6,966$ Mulch Material Type 1 14 Ton 200$ 2,800$ Disk Anchoring 7 Acre 100$ 700$

Subtotal 1,283,261$

Lift Station Quantity Unit Unit Price Total PriceStabilizing Aggreg. 100 Ton 27.40$ 2,740$ Agg. Base Class 5 250 Ton 13.00$ 3,250$ Dewatering 1 LS 4,000.00$ 4,000$ 4" Sch 80 PVC Forcemain 72 LF 80.00$ 5,760$ 6" Sch 80 PVC Forcemain 25 LF 80.00$ 2,000$ Pipe Fittings 729 LB 7.50$ 5,468$ 3" Steel Vent Pipe 1 Each 480.00$ 480$ 4" Flange Gate Valve 2 Each 800.00$ 1,600$ Meter 1 Each 2,500.00$ 2,500$ F&I Lift Station Pump System 1 LS 56,000.00$ 56,000$ F&I Lift Station Electrical System 1 LS 30,000.00$ 30,000$ 72" Lift Station #1 Wet Well w/ Access Hatch 1 LS 25,000.00$ 25,000$ 60" Valve Manhole 1 LS 12,000.00$ 12,000$ 48" Meter Manhole 1 LS 7,000.00$ 7,000$ Concrete Walk Special, 4" Walk 205 SF 8.00$ 1,640$ Temp. Construction Fence 175 LF 3.50$ 613$ Silt Fence Heavy Duty 215 LF 4.00$ 860$ Restoration/Site Grading 1 LS 8,500.00$ 8,500$

Subtotal 169,410$

Sewer Access Charge (One time fee) Quantity Unit Unit Price Total Price$500 per SAC unit (one SAC=274 gal/day) 604.4 SAC 500$ 302,200$ (115 gpm*60min*24hours)/274 gal per day=604.4 SAC Units

New LF Cap Quantity Unit Unit Price Total PriceNew LF cover 1 LS 5,000,000$ 5,000,000$

Subtotal 5,000,000$

Total 6,754,871$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceRoutine OMM (LF) 1 ls 90,000$ 90,000$ Groundwater recovery OMM 1 ls 50,000$ 50,000$ Annual Long Term Lift Station and Forcemain OMM 1 ls 53,800$ 53,800$ PW GAC/Bottled Water 1 ls 30,000$ 30,000$ Annual Sanitary Usage Costs ($2.88 per 1000 gallons) 60444 1000 gallons 2.88$ 174,079$ Annual MCES Add-on Service Charge ($0.84 per 1000 gallons) 60444 1000 gallons 0.84$ 50,773$

Subtotal 448,652$ Total 448,652$

ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue LF cover costs based on Washington County Landfill Alternative Selection Matrix - Cost provided by MNPCA115 gallons per minute sufficient for recovery of water beneath landfill with no infiltration (Barr)Costs do not include additional groundwater recovery wells, if necessaryCosts do not include any additional groundwater recovery capital investmentCost detail based on URS's June 22, 2007 Washington County Landfill Sanitary Forcemain, Phase II - Preparation of Feasibility-level Cost Estimates (Open Cut Option)

Preliminary Engineer's Cost Projection- Forcemain


Capital CostsItemGAC Treatment Process Equipment 358,700$ Non-Component Costs (% of Process Equipment total) 157,828$

Subtotal: 516,528$ Contingency 15% 77,479$ Detailed Engineering/Permits Fixed 120,000$ Engineering/Construction Oversight 10% 51,653$ Start up 5% 25,826$ Subtotal: 249,132$

New LF Cap 5,000,000$ Subtotal: 5,000,000$ Total Initial Capital Costs: 5,765,660$

Long Term Annual CostsItemOMMRoutine OMM (assumes 40 years operation) 90,000$ Groundwater recovery OMM (assumes 40 years operation) 50,000$ GAC Treatment OMM (assumes 40 years operation) 528,000$ PW GAC/Bottled Water (assumes 10 years operation) 30,000$ Subtotal: 698,000$ Contingency 0% -$ Total Annual OM&M Costs: 698,000$




DetailsCapital Costs (CRA: Appendix D, August 30, 2007)ItemGAC Treatment Process Equipment Quantity Unit Unit Price Total PriceEqualization Tank 1 each 14,000$ 14,000$ Birm Media Tanks 2 each 15,000$ 30,000$ Mix Tank 1 0 each 20,000$ -$ Activated Carbon Vessel 2 each 15,000$ 30,000$ Mix Tank 2 0 each 10,000$ -$ Backwash Holding Tank 1 each 6,800$ 6,800$ Sludge Settling Tank 1 each 11,600$ 11,600$ Sludge Tank Stand 1 each 3,700$ 3,700$ Sulfuric Acid Storage Tank 0 each 15,000$ -$ Caustic Storage Tank 0 each 8,000$ -$ Course Bubble Mixing System 1 each 10,000$ 10,000$ Groundwater Feed Pump 2 each 2,000$ 4,000$ Equalization Tank Pumps 2 each 3,500$ 7,000$ Chemical Metering Pumps 0 each 1,800$ -$ Decant Pump 1 each 1,000$ 1,000$ Slude Pump 1 each 1,000$ 1,000$ Backwash Pumps 2 each 5,000$ 10,000$ Containment Well Pump 1 each 1,100$ 1,100$ Magetic Flow Meter 1 each 3,000$ 3,000$ pH Sensors and Indicators 2 each 2,000$ 4,000$ Utrasonic Level Sensors and Indicators 5 each 1,000$ 5,000$ Pressure Transmitters 4 each 1,000$ 4,000$ Building 1 LS 187,500$ 187,500$ Chemical Unloading Station 0 LS 15,000$ -$ Sludge Holding Pond 1 LS 25,000$ 25,000$

Subtotal 358,700$

Non-Component Costs (% of Process Equipment total) Quantity Unit Unit Price Total PricePiping 12% $358,700 43,044$ Electrical 12% $358,700 43,044$ Instrumentation 10% $358,700 35,870$ Site Preparation 10% $358,700 35,870$

Subtotal 157,828$

New LF Cap Quantity Unit Unit Price Total PriceNewLF cover 1 LS 5,000,000$ 5,000,000$

Subtotal 5,000,000$

Total 5,516,528$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceRoutine OMM (LF) 1 ls 90,000$ 90,000$ Groundwater recovery OMM 1 ls 50,000$ 50,000$ GAC Treatment OMM 1 ls 528,000$ 528,000$ PW GAC/Bottled Water 1 ls 30,000$ 30,000$


ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue LF cover costs based on Washington County Landifll Alternative Selection Matrix - Cost provided by MNPCA150 gallons per minute sufficient for recovery of water beneath landfill (Barr/MPCA)Costs do not include additional groundwater recovery wells, if necessaryCosts assume discharge of treated groundwater to surfaceCosts assume that discharge of treated water to surface to not impact effectness of groundwater recovery systemTreatment technology utilizes GAC with no pH adjustmentEquipment, design, and contingency cost based on detail provided in CRA's August 30, 2007 Revised Cost Estimate for the Groundwater Treatment System at the Washington County Landfill (Appendix D) less costs associated with pH adjustmentAnnual OMM costs for GAC treatment based on cost provided in CRA's September 14, 2007 Column Adsorption Tests with Activated Carbon (Appendix E) for no pH adjustment (pH=8)Costs do not include any additional groundwater recovery capital investmentSpent GAC can be landfilled (non-hazardous)

Preliminary Engineer's Cost Projection- Pump and Treat


Capital CostsItemSite Preparation (Veolia) 2,733,083$ Waste Excavation/Load into Trucks (Veolia) 4,625,000$ Waste Transportation and Disposal (Veolia) 50,000,000$

Subtotal: 57,358,083$ Contingency 12% 6,882,970$ Detailed EngineeringEngineering 2% 1,147,162$ Engineering/Construction Oversight 2% 1,147,162$ Subtotal: 9,177,293$ Expand GAC/Bottled Water Coverage 307,998$ Subtotal: 307,998$ Total Initial Capital Costs: 66,843,374$



Present Worth Costs:Routine OMM GAC Private Well OMM/Limited LF OMMLong Term Operation Period, n (years) 40 years Long Term Operation Period, n (years) 10 yearsAverage Net Interest Rate, i 5% Average Net Interest Rate, i 5%Present Worth Factor (i, n) 17.159 Present Worth Factor (i, n) 7.722Annual OM&M Costs (40 years) -$

Annual OM&M Costs (10 years) 87,000$ Present Worth Long Term OM&M Costs (40 years) -$


DetailsCapital CostsItemSite Preparation/Restoration (Veolia) Quantity Unit Unit Price Total PriceMobilization/Bond 1 LS 1,650,000$ 1,650,000$ Temporary Construction Facilities and Utilities 1 LS 20,000$ 20,000$ Demolition and Removals 1 LS 15,000$ 15,000$ Stockpile Existing Cover Material 145050 CY 2.50$ 362,625$ Temp Access Roads 8361 LF 20$ 167,220$ Re-place and Grade Cover Material 145050 CY 2.50$ 362,625$ Restoration and Seeding 57.4 AC 1,200$ 68,880$ 6" Topsoil Outside Limits of Final Cover 16133 CY 2.50$ 40,333$ Install Perimeter Fencing 3450 LF 12$ 41,400$ Site Cleanup and Demob 1 LS 5,000$ 5,000$

Subtotal 2,733,083$

Waste Excavation/Load into Trucks (Veolia) Quantity Unit Unit Price Total PriceExcavation (2.5M yd3=2.5M Ton) 2,500,000 Ton 1.85$ 4,625,000$

Subtotal 4,625,000$

Waste Transportation and Disposal (Veolia) Quantity Unit Unit Price Total PriceHaul and Dispose at Special Waste LF 2,500,000 Ton 20$ 50,000,000$

Subtotal 50,000,000$


Subtotal 307,998$

Total 57,358,083$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceAnnual Routine LF OMM 1 ls 27,000$ 27,000$ PW GAC/Bottled Water 1 ls 60,000$ 60,000$


ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue Assumed that long-term routine OMM effort would require approximately 30% existing effort and be terminated within 10 years of waste excavationOMM effort associated with GAC/Bottled Water extracted from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assumes groundwater pumping system would be shut down to eliminate groundwater mound. As a result, the GAC treatment network would be expanded to account for likely expansion of contaminant plumeOMM costs associated with expanded GAC/Bottled Water program from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assume 2,500,000 cubic yards of waste materail in placeAssume weight of excavated waste at 1 ton per cubic yard (2000 lb/yd3)Cost detail based on estimates provided by Veolia ES Industrial Service. The estimates are intended for budgetary purposes.Cost details based on assumption that 4000 tons/day of waste material would be direct loaded to trucks. Equipment associated with this effort includes 2 excavators, 1 dozer, and one project manager.Restoration effort assumes only stockpiled cover soils would be used and excavation would not be completely backfilled. No borrow source is assumedCosts associated with daily cover requirements (Minnesota ARAR) included with contingency costsCosts associated with health and safety sampling and monitoring included with contingency costs

Preliminary Engineer's Cost Projection- Dig and Truck to Special Waste Landfill


Capital CostsItemSite Preparation (Veolia) 4,833,083$ Waste Excavation/Load into Trucks (Veolia) 4,625,000$ Waste Transportation and Disposal (Veolia) 120,000,000$

Subtotal: 129,458,083$ Contingency 11% 14,240,389$ Detailed EngineeringEngineering 1% 1,294,581$ Engineering/Construction Oversight 1% 1,294,581$ Subtotal: 16,829,551$ Expand GAC/Bottled Water Coverage 307,998$ Subtotal: 307,998$ Total Initial Capital Costs: 146,595,631$



Present Worth Costs:Routine OMM GAC Private Well OMM/Limited LF OMMLong Term Operation Period, n (years) 40 years Long Term Operation Period, n (years) 10 yearsAverage Net Interest Rate, i 5% Average Net Interest Rate, i 5%Present Worth Factor (i, n) 17.159 Present Worth Factor (i, n) 7.722Annual OM&M Costs (40 years) -$

Annual OM&M Costs (10 years) 87,000$ Present Worth Long Term OM&M Costs (40 years) -$


DetailsCapital CostsItemSite Preparation (Veolia) Quantity Unit Unit Price Total PriceMobilization/Bond 1 LS 3,750,000$ 3,750,000$ Temporary Construction Facilities and Utilities 1 LS 20,000$ 20,000$ Demolition and Removals 1 LS 15,000$ 15,000$ Stockpile Existing Cover Material 145050 CY 2.50$ 362,625$ Temp Access Roads 8361 LF 20$ 167,220$ Re-place and Grade Cover Material 145050 CY 2.50$ 362,625$ Restoration and Seeding 57.4 AC 1,200$ 68,880$ 6" Topsoil Outside Limits of Final Cover 16133 CY 2.50$ 40,333$ Install Perimeter Fencing 3450 LF 12$ 41,400$ Site Cleanup and Demob 1 LS 5,000$ 5,000$

Subtotal 4,833,083$

Waste Excavation/Load into Trucks (Veolia) Quantity Unit Unit Price Total PriceExcavation (2.5M yd3=2.5M Ton) 2,500,000 Ton 1.85$ 4,625,000$

Subtotal 4,625,000$

Waste Transportation and Disposal at MSW Landfill (Veolia) Quantity Unit Unit Price Total PriceHaul and Dispose at MSW 2,500,000 Ton 48$ 120,000,000$

Subtotal 120,000,000$


Subtotal 307,998$

Total 129,458,083$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceAnnual Routine LF OMM 1 ls 27,000$ 27,000$ PW GAC/Bottled Water 1 ls 60,000$ 60,000$


ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue Assumed that long-term routine OMM effort would require approximately 30% existing effort and be terminated within 10 years of waste excavationOMM effort associated with GAC/Bottled Water extracted from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assumes groundwater pumping system would be shut down to eliminate groundwater mound. As a result, the GAC treatment network would be expanded to account for likely expansion of contaminant plumeOMM costs associated with expanded GAC/Bottled Water program from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assume 2,500,000 cubic yards of waste materail in placeAssume weight of excavated waste at 1 ton per cubic yard (2000 lb/yd3)Cost detail based on estimates provided by Veolia ES Industrial Service. The estimates are intended for budgetary purposes.Cost details based on assumption that 4000 tons/day of waste material would be direct loaded to trucks. Equipment associated with this effort includes 2 excavators, 1 dozer, and one project manager.Restoration effort assumes only stockpiled cover soils would be used and excavation would not be completely backfilled. No borrow source is assumedCosts associated with daily cover requirements (Minnesota ARAR) included with contingency costsCosts associated with health and safety sampling and monitoring included with contingency costs

Preliminary Engineer's Cost Projection- Dig and Truck to MSW Landfill


Capital CostsItemSite Preparation (Alternative 2 URS-Table 1A) 5,500,764$ Construct New Landfill (Alternative 2 URS-Table 1A) 8,239,288$ Waste Excavation/Placement 7,611,297$

Subtotal: 21,351,349$ Contingency 15% 3,202,702$ Detailed Engineering/Permits 3% 640,540$ Engineering/Construction Oversight 10% 2,135,135$ Subtotal: 5,978,378$ Expand GAC/Bottled Water Coverage 307,998$ Subtotal: 307,998$ Total Initial Capital Costs: 27,637,724$






DetailsCapital Costs (Alternative 2 URS-Table 1A)ItemSite Preparation Quantity Unit Unit Price Total PriceMobilization 1 LS 619,587$ 619,587$ Temporary Construction Facilities and Utilities 6 LS 20,000$ 120,000$ Demolition and Removals 5 LS 15,000$ 75,000$ Stockpile Existing Cover Material 145050 CY 2.50$ 362,625$ Common Excavation 358746 CY 4$ 1,434,984$ Common Borrow 361071 CY 8$ 2,888,568$

Subtotal 5,500,764$

Construct New Landfill Quantity Unit Unit Price Total PriceInstall Liner 29.9 AC 95,550$ 2,856,945$ Install Leachate Collection Piping 5710 LF 50$ 285,500$ Install Leachate Collection Manhole 4 Each 20,000$ 80,000$ Install Leachate Collection Sideslope Riser Pipe 4 Each 10,000$ 40,000$ Install Leachate Collection Riser Vault Structure 4 Each 5,000$ 20,000$ Install Leachate Storage Tank LST-1 1 Each 50,000$ 50,000$ Install Leachate Loadout and Pump 1 Each 20,000$ 20,000$ Install Leachate Forcemain 3881 LF 40$ 155,240$ Install Electric Power Access 1 LS 135,000$ 135,000$ Install Leachate Recirculation System Pumps and Forcemain 1 LS 100,000$ 100,000$ Install Leachate Recirculation System Piping and Dist. Beds 59.8 AC 11,200$ 669,760$ Install LFG Wells 39 Each 5,000$ 195,000$ Install LFG 6" Laterals 2550 LF 27$ 68,850$ Install LFG 12" Header 5736 LF 33$ 189,288$ Install CST-1 2 Each 60,000$ 120,000$ Install LFG Blower/Flare 1 Each -$ -$ Temp Access Roads 8361 LF 20$ 167,220$ Install Access Roads over Landfill 1660 LF 20$ 33,200$ Temp Access Road (patch) 16678 LF 20$ 333,560$ Install Final Cover 30 AC 72,260$ 2,167,800$ Install LFG Wellheads 39 Each 1,500$ 58,500$ Install Berms 4259 LF 30$ 127,770$ Install Culverts 360 LF 50$ 18,000$ Install Riprap 9826 SY 17$ 167,042$ Restoration and Seeding 57.4 AC 1,200$ 68,880$ 6" Topsoil Outside Limits of Final Cover 16133 CY 2.50$ 40,333$ Install Perimeter Fencing 3450 LF 12$ 41,400$ Site Cleanup and Demob 6 LS 5,000$ 30,000$

Subtotal 8,239,288$

Waste Excavation/Placement Quantity Unit Unit Price Total PriceStockpile Waste Material 358,746 CY 2.50$ 896,865$ Excavate/Place Select Waste (min 6-ft prior to Dec 31) 289,432 CY 3.50$ 1,013,012$ Excavate/Place Remaining Waste material 2,280,568 LS 2.50$ 5,701,420$

Subtotal 7,611,297$


Subtotal 307,998$

Total 21,659,347$ Long Term Annual CostsItemOMM Quantity Unit Unit Price Total PriceRoutine OMM (LF) 1 ls 150,000$ 150,000$ PW GAC/Bottled Water 1 ls 60,000$ 60,000$


ASSUMPTIONSAnnual OMM costs per Shawn Ruotsinoja email. Recent historical OMM has ranged from $375K to $390K; however, >$'s due to expanded PFC investigation, which is assumed to not continue Assumed that long-term routine OMM effort associated with lined facility increases from existing effort due to cover maintenance, leachate conveyance OMM, and increased LFG recoveryCost detail based on URS's August 20, 2007 Washington County Landfill Remediation Feasibility Study Cost Estimates (50% Conceptual Design) for Alternative 2OMM effort associated with GAC/Bottled Water from Ingrid Verhagen's September 25, 2007, 2:24 pm email. Assumes groundwater pumping system would be shut down to eliminate groundwater mound. As a result, the GAC treatment network would be expanded to account for likely expansion of contaminant plumeIt does not appear that URS included costs associated with daily cover requirements (Minnesota ARAR); therefore, SEH increased contingency approximately 3% to account for the anticipated costsIt does not appear that URS included costs associated with health and safety sampling and monitoring; therefore, SEH increased contingency approximately 2% to account for estimated costs

Preliminary Engineer's Cost Projection- Dig and Line

Appendix C MPCA Cost Matrix

Appendix D URS Information

Appendix E CRA Information

remedy feasibility assessment

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