REMEDIAL INVESTIGATION REPORT FOR OPERABLE ...W.O. No.: 20083.500.006 1 Remedial Investigation...

VOLUME I of VIII: TEXT

REMEDIAL INVESTIGATION REPORT FOR OPERABLE UNIT ONE

VELSICOL CHEMICAL CORPORATION SUPERFUND SITE ST. LOUIS, GRATIOT COUNTY, MICHIGAN

Prepared for:

MICHIGAN DEPARTMENT OF ENVIRONMENTAL QUALITY REMEDIATION AND REDEVELOPMENT DIVISION

SUPERFUND SECTION Constitution Hall 3rd Floor SW

525 West Allegan Street Lansing, Michigan 48913

Prepared by:

Weston Solutions of Michigan, Inc. 2501 Jolly Road, Suite 100 Okemos, Michigan 48864

November 2006

W.O. No.: 20083.500.006

1

Remedial Investigation Report for Weston Solutions of Michigan, Inc. OU-1 – Velsicol Chemical Corporation Superfund Site

TABLE OF CONTENTS

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TABLE OF CONTENTS

VOLUME I OF VIII

Section Page

ES EXECUTIVE SUMMARY ........................................................................................ ES-1 1 INTRODUCTION.......................................................................................................... 1-1 1.1 PROJECT SCOPE AND OBJECTIVES............................................................. 1-2 1.1.1 Purpose and Scope of Project .................................................................. 1-2 1.1.2 RI Objectives ........................................................................................... 1-3 1.2 SITE INFORMATION ........................................................................................ 1-5 1.2.1 Site Location ............................................................................................ 1-5 1.2.2 Site History .............................................................................................. 1-6 1.3 REGIONAL SETTING ..................................................................................... 1-10 1.3.1 Climate................................................................................................... 1-10 1.3.2 Ecology .................................................................................................. 1-11 1.3.3 Topography............................................................................................ 1-11 1.3.4 Surface Water......................................................................................... 1-12 1.3.5 Geology.................................................................................................. 1-13 1.3.5.1 Surface Soil............................................................................. 1-13 1.3.5.2 Unconsolidated Deposits ........................................................ 1-14 1.3.5.3 Bedrock ................................................................................... 1-15 1.3.6 Hydrogeology ........................................................................................ 1-16 1.3.7 Previous Site Investigation Work .......................................................... 1-18 1.3.8 Other Related Investigations.................................................................. 1-25 1.3.8.1 Pine River Investigations ........................................................ 1-26 1.3.8.2 Former Burn Area Investigations............................................ 1-26 1.3.9 Previous Environmental Response Activates ........................................ 1-27 2 SUMMARY OF SITE INVESTIGATION ACTIVITIES ......................................... 2-1 2.1 PHYSICAL INVESTIGATION ACTIVITIES ................................................... 2-1 2.1.1 Phase I Investigation................................................................................ 2-1 2.1.1.1 Historic Data Review................................................................ 2-1 2.1.1.2 File Management Support......................................................... 2-2 2.1.1.3 Topographic Surveys ................................................................ 2-3 2.1.1.4 Thermal Infrared Survey........................................................... 2-4 2.1.1.5 Slurry Wall Location Activities ................................................ 2-5 2.1.1.6 VAS Borings and Piezometer Installations............................... 2-6 2.1.1.7 Residual Contamination Borings .............................................. 2-8 2.1.1.8 October 2001 Seep Sampling Activities ................................... 2-9 2.1.1.9 Slurry Wall Vertical Borings .................................................. 2-10 2.1.1.10 Groundwater Flow Evaluation................................................ 2-10 2.1.1.11 City of St. Louis Municipal Well Sampling ........................... 2-11 2.1.2 Phase II Investigation............................................................................. 2-11

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TABLE OF CONTENTS (Cont’d)

VOLUME I OF VIII

Section Page

2.1.2.1 Historic Data Review.............................................................. 2-11 2.1.2.2 Supplemental Slurry Wall Evaluation .................................... 2-11 2.1.2.3 Till Unit Evaluation ................................................................ 2-17 2.1.2.4 Monitoring Well Installation................................................... 2-19 2.1.2.5 Site-Wide Groundwater Flow Evaluation............................... 2-22 2.1.2.6 Hydraulic Conductivity Testing.............................................. 2-23 2.1.2.7 Additional Phase II Activities................................................. 2-26 2.1.2.8 NAPL Extent Evaluation ........................................................ 2-29 2.1.2.9 Topographic Surveys .............................................................. 2-30 2.1.3 Phase III Investigation ........................................................................... 2-31 2.1.3.1 Former Burn Area Investigation ............................................. 2-31 2.1.3.2 Shallow Outwash Unit Investigation ...................................... 2-35 2.1.3.3 Monitoring Well Installation................................................... 2-40 2.1.3.4 Groundwater Sampling/Depth to Water Measurements ......... 2-42 2.1.4 Additional Investigation for ERA and HHRA....................................... 2-44 2.1.4.1 Soil Gas................................................................................... 2-45 2.1.4.2 Surface Water.......................................................................... 2-46 2.1.4.3 Sediment ................................................................................. 2-46 2.1.4.4 Biota........................................................................................ 2-49 2.2 ANALYTICAL PROGRAM............................................................................. 2-53 2.2.1 Field Procedures..................................................................................... 2-53 2.2.1.1 Analytical Laboratory Procedures .......................................... 2-54 2.2.1.2 Field QA/QC Samples ............................................................ 2-55 2.2.2 Laboratory.............................................................................................. 2-55 2.2.2.1 Laboratory Certification.......................................................... 2-55 2.2.2.2 Laboratory QA/QC Methods .................................................. 2-56 2.2.3 Analytical Data Management ................................................................ 2-56 2.2.3.1 Data Reduction, Validation, and Reporting............................ 2-56 2.2.3.2 Data Management and Geographical Information System

(GIS) Support......................................................................... 2-57 2.3 INVESTIGATION DERIVED WASTE HANDLING ..................................... 2-58 3 RESULTS ....................................................................................................................... 3-1 3.1 LOCAL GEOLOGY AND HYDROGEOLOGY................................................ 3-1 3.1.1 Local Geology.......................................................................................... 3-1 3.1.1.1 Unconsolidated Deposits .......................................................... 3-1 3.1.1.2 Bedrock ..................................................................................... 3-5 3.1.2 Hydrostratigraphic Units.......................................................................... 3-6 3.1.2.1 Shallow Outwash Unit Water-Producing Intervals................... 3-6 3.1.2.2 Till Unit Water-Bearing Intervals............................................. 3-7

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Section Page

3.1.2.3 Lower Outwash Unit Water-Producing Intervals ..................... 3-8 3.1.2.4 Bedrock Unit............................................................................. 3-9 3.1.3 Local Groundwater Flow ......................................................................... 3-9 3.1.3.1 Shallow Outwash Unit Water-Producing Intervals................. 3-10 3.1.3.2 Till Unit Water-Bearing Intervals........................................... 3-11 3.1.3.3 Lower Outwash Unit Water-Producing Intervals ................... 3-12 3.1.3.4 Hydraulic Gradients ................................................................ 3-13 3.1.3.5 Groundwater Velocities .......................................................... 3-18 3.1.3.6 Aquifer Performance Results.................................................. 3-21 3.2 CONTAINMENT SYSTEM CHARACTERISTICS........................................ 3-27 3.2.1 Slurry Wall............................................................................................. 3-27 3.2.2 Till Unit.................................................................................................. 3-29 3.3 ANALYTICAL RESULTS ............................................................................... 3-31 3.3.1 Former Plant Site and Adjacent or Nearby Properties Soil Results....... 3-34 3.3.1.1 VOCs....................................................................................... 3-36 3.3.1.2 SVOCs .................................................................................... 3-38 3.3.1.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-40 3.3.1.4 Inorganics................................................................................ 3-44 3.3.2 Former Burn Area Soil Results.............................................................. 3-49 3.3.2.1 VOCs....................................................................................... 3-50 3.3.2.2 SVOCs .................................................................................... 3-50 3.3.2.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-51 3.3.2.4 Inorganics................................................................................ 3-52 3.3.3 Residential Surface Soil Analytical Results .......................................... 3-54 3.3.4 Former Plant Site and Adjacent or Nearby Properties VAS Results ..... 3-56 3.3.4.1 VOCs....................................................................................... 3-57 3.3.4.2 SVOCs .................................................................................... 3-60 3.3.4.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-62 3.3.4.4 Inorganics................................................................................ 3-66 3.3.5 Former Burn Area VAS Analytical Results........................................... 3-72 3.3.5.1 VOCs....................................................................................... 3-72 3.3.5.2 SVOCs .................................................................................... 3-73 3.3.5.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-73 3.3.5.4 Inorganics................................................................................ 3-73 3.3.6 Former Plant Site and Adjacent or Nearby Properties Monitoring Well Sampling Results........................................................................... 3-75 3.3.6.1 VOCs....................................................................................... 3-77 3.3.6.2 SVOCs .................................................................................... 3-83 3.3.6.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-85

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Section Page

3.3.6.4 Inorganics................................................................................ 3-89 3.3.7 Former Burn Area Monitoring Well Sampling Analytical Results ....... 3-92 3.3.7.1 VOCs....................................................................................... 3-93 3.3.7.2 SVOCs .................................................................................... 3-95 3.3.7.3 Pesticides, PCBs, and Specialty Chemicals. ........................... 3-96 3.3.7.4 Inorganics................................................................................ 3-98 3.3.8 October 2001 Seep Sampling Results.................................................. 3-100 3.3.9 NAPL and Manhole Sampling Analytical Results .............................. 3-100 3.3.10 Sediment Pore Water and Surface Water Analytical Results .............. 3-103 3.3.11 Municipal Well and Residential Well Sampling Analytical Results ... 3-103 3.3.12 Water Quality Parameters Analytical Results...................................... 3-105 3.3.13 Radiological Analyses ......................................................................... 3-107 3.3.14 Dioxin Analytical Results .................................................................... 3-109 3.3.15 PBDE Analyses.................................................................................... 3-110 3.3.16 pCBSA Analyses ................................................................................. 3-111 3.3.17 Tritium Analytical Results................................................................... 3-112 3.3.18 Additional Analytical Results for Ecological and Human Health

Risk Assessments................................................................................. 3-114 3.3.18.1 Soil Gas................................................................................. 3-114 3.3.18.2 Surface Water........................................................................ 3-115 3.3.18.3 In-stream Sediment ............................................................... 3-117 3.3.18.4 Floodplain Sediment ............................................................. 3-119 3.3.18.5 Aquatic Biota ........................................................................ 3-120 3.3.18.6 Terrestrial Biota .................................................................... 3-122

4 RISK EVALUATION.................................................................................................... 4-1 4.1 HHRA .................................................................................................................. 4-1 4.2 ERA...................................................................................................................... 4-8 5 DISCUSSION ................................................................................................................. 5-1 5.1 SITE HYDROGEOLOGY................................................................................... 5-1 5.1.1 Significant Influences on Groundwater Flow.......................................... 5-1 5.1.2 Slurry Wall............................................................................................... 5-4 5.1.3 Sand Lenses within the Till Unit ............................................................. 5-4 5.1.4 Lower Outwash Unit Water-Producing Intervals .................................... 5-5 5.1.5 City of St. Louis Municipal Wells ........................................................... 5-5 5.2 NATURE AND EXTENT OF CONTAMINATION.......................................... 5-7 5.2.1 Nature and Extent of Contamination in Soil............................................ 5-7 5.2.1.1 VOCs .......................................................................................... 5-8 5.2.1.2 SVOCs........................................................................................ 5-9 5.2.1.3 Pesticides, PCBs, and Specialty Chemicals ............................. 5-11

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5.2.1.4 Inorganics ................................................................................. 5-12 5.2.1.5 Radionuclides ........................................................................... 5-14 5.2.2 Nature and Extent of Contamination in Groundwater ........................... 5-14 5.2.2.1 Shallow Outwash Unit Water-Producing Intervals .................. 5-15 5.2.2.2 Till Unit Water-Bearing Intervals ............................................ 5-21 5.2.2.3 Lower Outwash Unit Water-Producing Intervals..................... 5-23

5.2.2.4 Other Compounds Detected and Analyzed for in Groundwater ............................................................................. 5-26

5.2.3 Extent of Contamination in Sediment Pore Water and Surface Water...................................................................................................... 5-28 5.2.3.1 Seep Sampling.......................................................................... 5-28 5.2.3.2 VOCs ........................................................................................ 5-28 5.2.3.3 SVOCs...................................................................................... 5-28 5.2.3.4 Pesticides, PCBs, and Specialty Chemicals ............................. 5-29 5.2.3.5 Inorganics ................................................................................. 5-29 5.3 NAPL OBSERVATIONS.................................................................................. 5-29 5.3.1 NAPL Characteristics ............................................................................ 5-30 5.3.2 NAPL Boring Investigation Area .......................................................... 5-31 5.3.3 NAPL Extent.......................................................................................... 5-31 5.4 SOURCES OF CONTAMINATION ................................................................ 5-32 5.4.1 Residual Fill Materials........................................................................... 5-32 5.4.2 Disposal Area and Debris Refuse Yard ................................................. 5-33 5.4.3 NAPL Area ............................................................................................ 5-33 5.4.4 Former Petroleum Release Area ............................................................ 5-33 5.5 FATE AND TRANSPORT................................................................................ 5-33 5.5.1 Contaminant Migration Pathways.......................................................... 5-34 5.5.1.1 Soil and Sediment..................................................................... 5-34 5.5.1.2 Groundwater ............................................................................. 5-36 5.6 CONTAMINANT TRANSPORT CHARACTERISTICS FOR COCs ........... 5-37 5.6.1 Conceptual Model of Contaminant Migration....................................... 5-38 5.6.2 Fate and Transport Characteristics......................................................... 5-39 6 CONCLUSIONS AND RECOMMENDATIONS....................................................... 6-1 6.1 CONCLUSIONS.................................................................................................. 6-1 6.1.1 Containment System ................................................................................ 6-1 6.1.1.1 Cap.............................................................................................. 6-1 6.1.1.2 Slurry Wall ................................................................................. 6-1 6.1.1.3 Till Unit ...................................................................................... 6-2 6.1.2 Hydrogeology .......................................................................................... 6-3

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Section Page 6.1.2.1 Shallow Outwash Unit Water-Producing Intervals .................... 6-3 6.1.2.2 Till Unit Water-Bearing Intervals .............................................. 6-4 6.1.2.3 Lower Outwash Unit Water-Producing Intervals....................... 6-5 6.1.3 COCs ...................................................................................................... 6-7 6.1.4 Extent of Contamination .......................................................................... 6-7 6.1.4.1 Source Areas and Extent of Soil and Groundwater Contamination ............................................................................ 6-7 6.1.4.2 Extent of Soil Contamination ................................................... 6-10 6.1.4.3 Shallow Outwash Unit Water-Producing Intervals .................. 6-10 6.1.4.4 Till Unit Water-Bearing Intervals ............................................ 6-12 6.1.4.5 Lower Outwash Unit Water-Producing Intervals..................... 6-12 6.1.4.6 NAPL........................................................................................ 6-13 6.2 RECOMMENDATIONS................................................................................... 6-14 6.2.1 Former Plant Site and Adjacent or Nearby Properties........................... 6-14 6.2.2 Former Burn Area .................................................................................. 6-15 7 REFERENCES............................................................................................................... 7-1

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LIST OF TABLES

VOLUME II OF VIII

Title Table 2-1 Soil Boring Summary

Table 2-2 Monitoring Well and Piezometer Construction Summary

Table 2-3a Phase I Groundwater Elevation Summary

Table 2-3b Phase II Groundwater Elevation Summary

Table 2-3c Phase III Groundwater Elevation Summary

Table 3-1 Vertical Hydraulic Gradients

Table 3-2 Summary of Geotechnical Results

Table 3-3 Fluorimetric Analysis Results

Table 3-4 Project Analyte List

Table 3-5 Contaminants of Potential Concern (COPCs)

Table 3-6 Soil Sample Summary

Table 3-7 Phase I and II Soil Analytical Results: VOCs

Table 3-8 Phase III Grid Soil Analytical Results: VOCs

Table 3-9 Phase III Residential Geoprobe Investigation Soil Analytical Results

Table 3-10 Phase I and II Soil Analytical Results: SVOCs

Table 3-11 Phase III Grid Soil Analytical Results: SVOCs

Table 3-12 Phase I and II Soil Analytical Results: Pesticides, PCBs, and Specialty Chemicals Table 3-13 Phase III Grid Soil Analytical Results: Pesticides, PCBs, and Specialty Chemicals Table 3-14 Phase I and II Soil Analytical Results: Inorganics

Table 3-15 Phase III Grid Soil Analytical Results: Inorganics

Table 3-16 Phase III Former Burn Area Soil Analytical Results

Table 3-17 Burned Material Piles Sample Analytical Results

Table 3-18 Phase III Residential Surface Soil Analytical Results

Table 3-19 Residential Surface Soil Analytical Results – Previous Investigations

Table 3-20 VAS Sample Summary

Table 3-21 Phase I and II VAS Analytical Results: VOCs

Table 3-22 Phase III Grid VAS Analytical Results: VOCs

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LIST OF TABLES (Cont’d)

VOLUME II OF VIII

Title Table 3-23 Phase III Deep Monitoring Well Installation VAS Analytical Results

Table 3-24 Phase III Residential Geoprobe VAS Analytical Results

Table 3-25 Phase I and II VAS Analytical Results: SVOCs

Table 3-26 Phase III Grid VAS Analytical Results: SVOCs

Table 3-27 Phase I and II VAS Analytical Results: Pesticides, PCBs, and Specialty Chemicals

Table 3-28 Phase III Grid VAS Analytical Results: Pesticides, PCBs, and Specialty Chemicals

Table 3-29 Phase I and II VAS Analytical Results: Inorganics

Table 3-30 Phase III Grid VAS Analytical Results: Inorganics

Table 3-31 Phase III Former Burn Area VAS Analytical Results

Table 3-32 Groundwater Sample Summary

Table 3-33 Groundwater Analytical Results: VOCs

Table 3-34 Groundwater Analytical Results: SVOCs

Table 3-35 Groundwater Analytical Results: Pesticides, PCBs, and Specialty Chemicals

Table 3-36 Groundwater Analytical Results: Inorganics

Table 3-37 Former Burn Area Groundwater Analytical Results

Table 3-38 October 2001 Seep Sample Analytical Results

Table 3-39 NAPL and Manhole Sample Results

Table 3-40 Sediment Pore Water and Surface Water Analytical Results

Table 3-41 Municipal and Residential Well Analytical Results

Table 3-42 Phase I and II VAS Analytical Results: Water Quality Parameters

Table 3-43 Phase I and II Groundwater Analytical Results: Water Quality Parameters

Table 3-44 Phase III Groundwater Analytical Results: Water Quality Parameters

Table 3-45 Phase I, II, and III Radionuclide Analytical Results

Table 3-46 Phase I and II Dioxin Analytical Results

Table 3-47 Phase III Grid VAS Dioxin Analytical Results

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LIST OF TABLES (Cont’d)

VOLUME II OF VIII

Title Table 3-48 Polybrominated Diphenyl Ether Analytical Results

Table 3-49 pCBSA Analytical Results

Table 3-50 Phase III Groundwater Tritium Analytical Results

Table 3-51 Methane Soil Gas Survey Results

Table 3-52 Active Soil Gas Analytical Results

Table 3-53 Surface Water Sample Analytical Results

Table 3-54 St. Louis Impoundment Sediment Analytical Results

Table 3-55 Downstream Sediment Analytical Results

Table 3-56 Floodplain 1 Sediment Analytical Results

Table 3-57 Floodplain 3 (Reference Area) Soil Analytical Results

Table 3-58 Bass, Carp, and Sucker Tissue Analytical Results

Table 3-59 Downstream Aquatic Biota Tissue Analytical Results

Table 3-60 St. Louis Impoundment Forage Fish Analytical Results

Table 3-61 Downstream Terrestrial Biota Analytical Results

Table 5-1 Characteristics of Selected Chemicals of Potential Concern

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LIST OF FIGURES

VOLUME III OF VIII

Title Figure 1-1 Site Location Map

Figure 1-2 Aerial Photograph (April 2003) and Property Boundaries

Figure 1-3 Former Site Conditions (1950/1975)

Figure 1-4 Monitoring Well Location Map

Figure 1-5 Surface Water Drainage Network

Figure 1-6 Soil Boring Location Map

Figure 1-7 Generalized Stratigraphic Column

Figure 1-8 Generalized Cross Section and Fence Diagram Location Map

Figure 1-9 Generalized Cross Section A-A’

Figure 1-10 Generalized Cross Section B-B’

Figure 1-11 Generalized Geologic Fence Diagram

Figure 2-1 NAPL Investigation Area Map

Figure 2-2 City Well Location Map

Figure 2-3 Dye Study Map

Figure 2-4 Reference Area 1 Sample Locations

Figure 2-5 St. Louis Impoundment, Former Burn Area and Former Plant Site Sample Locations

Figure 2-6 Floodplain 1 and DS-1 Sample Locations

Figure 2-7 Floodplain 1 Sample Locations

Figure 3-1 Detailed Cross Section Location Map

Figure 3-2 Geological Cross Section C-C’

Figure 3-3 Geological Cross Section D-D’

Figure 3-4 Geological Cross Section E-E’

Figure 3-5 Geological Cross Section F-F’

Figure 3-6 Geological Cross Section G-G’

Figure 3-7 Top of Till Elevation Contour Map

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LIST OF FIGURES (Cont’d)

VOLUME III OF VIII

Title Figure 3-8 Shallow Outwash Water-Producing Intervals 24 May 2005 Groundwater Flow Map

Figure 3-9 Shallow Outwash Water-Producing Intervals 12 September 2005 Groundwater Flow Map

Figure 3-10 Shallow Outwash Water-Producing Intervals 30 September 2005 Groundwater Flow Map

Figure 3-11a Upper Till Water-Bearing Intervals 24 May 2005 Groundwater Flow Map

Figure 3-11b Lower Till Water-Bearing Intervals 24 May 2005 Groundwater Flow Map

Figure 3-12a Upper Till Water-Bearing Intervals 12 September 2005 Groundwater Flow Map Figure 3-12b Lower Till Water-Bearing Intervals 12 September 2005 Groundwater Flow Map Figure 3-13a Upper Till Water-Bearing Intervals 30 September 2005 Groundwater Flow Map Figure 3-13b Lower Till Water-Bearing Intervals 30 September 2005 Groundwater Flow Map Figure 3-14 Lower Outwash Water-Producing Intervals 24 May 2005 Groundwater Flow Map

Figure 3-15 Lower Outwash Water-Producing Intervals 12 September 2005 Groundwater Flow Map

Figure 3-16 Lower Outwash Water-Producing Intervals 30 September 2005 Groundwater Flow Map

VOLUME IV OF VIII

Figure 3-17a Former Plant Site Soil Samples – North Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Drinking Water Protection Criteria

Figure 3-17b Former Plant Site Soil Samples – South Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Drinking Water Protection Criteria

Figure 3-17c Former Burn Area and Residential Soil Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Drinking Water Protection Criteria

Figure 3-18a Former Plant Site Soil Samples – North Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Surface Water Interface Protection Criteria

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VOLUME IV OF VIII

Title Figure 3-18b Former Plant Site Soil Samples – South Detected VOCs, SVOCs, Pesticides,

PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Surface Water Interface Protection Criteria

Figure 3-18c Former Burn Area and Residential Soil Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Surface Water Interface Protection Criteria

Figure 3-19a Former Plant Site Soil Samples – North Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Soil Volatilization to Indoor Air Inhalation Criteria

Figure 3-19b Former Plant Site Soil Samples – South Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Soil Volatilization to Indoor Air Inhalation Criteria

Figure 3-19c Former Burn Area and Residential Soil Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Soil Volatilization to Indoor Air Inhalation Criteria

Figure 3-20a Former Plant Site Soil Samples – North Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Direct Contact Criteria

Figure 3-20b Former Plant Site Soil Samples – South Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Direct Contact Criteria

Figure 3-20c Former Burn Area and Residential Soil Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Direct Contact Criteria

Figure 3-21 Phase III Vertical Aquifer Sampling Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Drinking Water Criteria

Figure 3-22 Phase III Vertical Aquifer Sampling Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Surface Water Interface Criteria

Figure 3-23 Phase III Vertical Aquifer Sampling Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Volatilization to Indoor Air Inhalation Criteria

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VOLUME IV OF VIII

Title Figure 3-24 Phase III Vertical Aquifer Sampling Detected VOCs, SVOCs, Pesticides, PCBs,

and Specialty Chemicals MDEQ Part 201 Groundwater Contact Criteria

Figure 3-25 October 2005 Groundwater Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Drinking Water Criteria

Figure 3-26 October 2005 Groundwater Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Surface Water Interface Criteria

Figure 3-27 October 2005 Groundwater Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Volatilization to Indoor Air Inhalation Criteria

Figure 3-28 October 2005 Groundwater Samples Detected VOCs, SVOCs, Pesticides, PCBs, and Specialty Chemicals MDEQ Part 201 Groundwater Contact Criteria

VOLUME V OF VIII

Figure 5-1 4-4’-DDT Soil Isoconcentration Map Figure 5-2 Residential Surface Soil (0-0.5 feet bgs) 4,4’-DDT Soil Isoconcentration and PBB

Results Map

Figure 5-3 Shallow Outwash Water-Producing Intervals May/June 2005 Benzene Groundwater Isoconcentration Map

Figure 5-4 Shallow Outwash Water-Producing Intervals October 2005 Benzene Groundwater Isoconcentration Map

Figure 5-5 Shallow Outwash Water-Producing Intervals May/June 2005 Chlorobenzene Groundwater Isoconcentration Map

Figure 5-6 Shallow Outwash Water-Producing Intervals October 2005 Chlorobenzene Groundwater Isoconcentration Map

Figure 5-7 Shallow Outwash Water-Producing Intervals May/June 2005 Trichloroethene Groundwater Isoconcentration Map

Figure 5-8 Shallow Outwash Water-Producing Intervals October 2005 Trichloroethene Groundwater Isoconcentration Map

Figure 5-9 Shallow Outwash Water-Producing Intervals May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Map

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Title Figure 5-10 Shallow Outwash Water-Producing Intervals October 2005 1,2-Dichloroethane Groundwater Isoconcentration Map

Figure 5-11 Shallow Outwash Water-Producing Intervals May/June 2005 Vinyl Chloride Groundwater Isoconcentration Map

Figure 5-12 Shallow Outwash Water-Producing Intervals October 2005 Vinyl Chloride Groundwater Isoconcentration Map

Figure 5-13 Geological Cross Section C-C’ May/June 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-14 Geological Cross Section C-C’ October 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-15 Geological Cross Section C-C’ May/June 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-16 Geological Cross Section C-C’ October 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-17 Geological Cross Section C-C’ May/June 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-18 Geological Cross Section C-C’ October 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-19 Geological Cross Section C-C’ May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-20 Geological Cross Section C-C’ October 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-21 Geological Cross Section D-D’ May/June 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-22 Geological Cross Section D-D’ October 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-23 Geological Cross Section D-D’ May/June 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-24 Geological Cross Section D-D’ October 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-25 Geological Cross Section D-D’ May/June 2005 Trichloroethene Groundwater Isoconcentration Contours

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VOLUME V OF VIII

Title Figure 5-26 Geological Cross Section D-D’ October 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-27 Geological Cross Section D-D’ May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-28 Geological Cross Section D-D’ October 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-29 Geological Cross Section E-E’ May/June 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-30 Geological Cross Section E-E’ October 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-31 Geological Cross Section E-E’ May/June 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-32 Geological Cross Section E-E’ October 2005 Chlorobenzene Groundwater Isoconcentration Contours

VOLUME VI OF VIII

Figure 5-33 Geological Cross Section E-E’ May/June 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-34 Geological Cross Section E-E’ October 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-35 Geological Cross Section E-E’ May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-36 Geological Cross Section E-E’ October 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-37 Geological Cross Section F-F’ May/June 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-38 Geological Cross Section F-F’ October 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-39 Geological Cross Section F-F’ May/June 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-40 Geological Cross Section F-F’ October 2005 Chlorobenzene Groundwater Isoconcentration Contours

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VOLUME VI OF VIII

Title Figure 5-41 Geological Cross Section F-F’ May/June 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-42 Geological Cross Section F-F’ October 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-43 Geological Cross Section F-F’ May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-44 Geological Cross Section F-F’ October 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-45 Geological Cross Section G-G’ May/June 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-46 Geological Cross Section G-G’ October 2005 Benzene Groundwater Isoconcentration Contours

Figure 5-47 Geological Cross Section G-G’ May/June 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-48 Geological Cross Section G-G’ October 2005 Chlorobenzene Groundwater Isoconcentration Contours

Figure 5-49 Geological Cross Section G-G’ May/June 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-50 Geological Cross Section G-G’ October 2005 Trichloroethene Groundwater Isoconcentration Contours

Figure 5-51 Geological Cross Section G-G’ May/June 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-52 Geological Cross Section G-G’ October 2005 1,2-Dichloroethane Groundwater Isoconcentration Contours

Figure 5-53 Shallow Outwash Water-Producing Intervals October 2005 pCBSA Groundwater Results Isoconcentration Map

Figure 5-54 Till Water-Bearing Intervals October 2005 pCBSA Groundwater Results Isoconcentration Map

Figure 5-55 Lower Outwash Water-Producing Intervals October 2005 pCBSA Groundwater Results Isoconcentration Map

Figure 5-56 Geological Cross Section C-C’ October 2005 pCBSA Groundwater Isoconcentration Contours

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VOLUME VI OF VIII

Title Figure 5-57 Geological Cross Section D-D’ October 2005 pCBSA Groundwater Isoconcentration Contours

Figure 5-58 Geological Cross Section E-E’ October 2005 pCBSA Groundwater Isoconcentration Contours

Figure 5-59 Geological Cross Section F-F’ October 2005 pCBSA Groundwater Isoconcentration Contours

Figure 5-60 Geological Cross Section G-G’ October 2005 pCBSA Groundwater Isoconcentration Contours

Figure 5-61 Shallow Outwash Water-Producing Intervals Tritium Groundwater Results Map

Figure 5-62 Till Water-Bearing Intervals Tritium Groundwater Results Isoconcentration Map

Figure 5-63 Lower Outwash Water-Producing Intervals Tritium Groundwater Results Isoconcentration Map

Figure 5-64 Potential Contaminant Transport Pathways

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LIST OF APPENDICES

VOLUMES VII and VIII OF VIII

(INCLUDED ON CD)

Title Appendix A Boring Logs/Well Construction Diagrams

Appendix B Historical Photographs

Appendix C Survey Data

Appendix D Site Photographs

Appendix E Geotechnical Data

Appendix F Dye Study Data

Appendix G Transducer Data

Appendix H Hydraulic Conductivity Testing

Appendix I Aquifer Performance Testing

Appendix J Laboratory Data Validation Reports

Appendix K Laboratory Data

Appendix L Human Heath and Ecological Risk Assessments

Appendix M Groundwater Sampling Forms

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GLOSSARY OR ACRONYMS AND ABBREVIATIONS

µg/Kg micrograms per kilogram

µg/L micrograms per liter

Abrams Abrams Aerial Survey Corporation

ALTA Alta Analytical

APT Aquifer Performance Tests

ASTM American Society for Testing and Materials

ATV All-Terrain Vehicle

BAFs Bioaccumulation Factors

BERA Baseline Ecological Risk Assessment

bgs below ground surface

BHC Alpha-hexachlorocyclohexane

CAD Computer Aided Design

CDD Chlorinated Dibenzo-p-dioxin

CDF Chlorinated Dibenzofuran

CDM Camp, Dresser, and McKee

CJ Consent Judgment

CLP Contract Laboratory Program

cm/s centimeters per second

COC Contaminant of Concern

COPC Contaminants of Potential Concern

CRA Conestoga-Rover & Associates Limited

Crawford Crawford Hydrology Laboratory at the Center for Cave and Karst Studies

CRL Central Regional Laboratory of Chicago

CSA Containment System Assessment

CW City Well

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GLOSSARY OR ACRONYMS AND ABBREVIATIONS (Cont’d)

DBCP 1,2-dibromo-3-chloropropane

DC Direct Contact

1,2-DCA 1,2-Dichloroethane

4,4’-DDD Tetrachlorodiphenylethane

4,4’-DDE Dichlorodiphenyldichloroethane

DDT Dichlorodiphenyl trichloroethane

DI Deionized

DNAPL Dense Non-Aqueous Phase Liquid

DO Dissolved Oxygen

DOE Department of Energy

DW Drinking Water

DWP Drinking Water Protection

Dynecol Dynecol, Inc.

EDD Electronic Deliverable Document

E&E Ecology and Environment

EM Electromagnetic

email electronic mail

EPCs Exposure Point Concentrations

ERA Ecological Risk Assessment

ERD Environmental Response Division

FP-1 Floodplain 1

FP-3 Floodplain 3

FS Feasibility Study

ft feet

ft/day feet per day

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ft2/day square feet per day

ft/ft feet per foot

GC Groundwater Contact

GIS Geographic Information System

GSI Groundwater-Surface Water Interface

GSIP Groundwater-Surface Water Interface Protection

GVIAI Groundwater Volatilization to Indoor Air Inhalation

HBB Hexabromobenzene

HHRA Human Health Risk Assessment

HQ Hazard Quotient

HSA Hollow-Stem Auger

I Hydraulic Gradient

ID Inner Diameter

IDW Investigation Derived Waste

In-Situ In-Situ, Inc.

JSAP Joint Sampling and Analysis Plan

K Hydraulic Conductivity

LNAPL Light Non-Aqueous Phase Liquid

LOAEL Low Observed Adverse Effect Level

LTMP Long Term Monitoring Program

MCC Michigan Chemical Corporation

MDEQ Michigan Department of Environmental Quality

MDNR Michigan Department of Natural Resources

MEC Memphis Environmental Center, Inc.

mg/m3 milligrams per cubic meter

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mg/kg milligrams per kilogram

mg CaCO3/L milligrams of calcium carbonate per liter

MH Manhole

ml/min milliliters per minute

MNA Monitored Natural Attenuation

MS/MSD Matrix spike/matrix spike duplicate

msl Mean Sea Level

MTBE Methyl tertiary butyl ether

NAPL Non-Aqueous Phase Liquid

NAS National Academy of Sciences

NAVD North American Vertical Datum

n℮ Effective Porosity

NEA Northeast Analytical Labs

NEIC National Enforcement Investigation Center

ng/Kg nanograms per kilogram

NOAEL No Observed Adverse Effect Level

O&M Operation and Maintenance

ORP Oxidation Reduction Potential

OU-1 Operable Unit One

OU-2 Operable Unit Two

OW Observation Well

PBB Polybrominated biphenyls

PBDE Polybrominated diphenyl ether

PCBs Polychlorinated biphenyls

pCBSA para-Chlorobenzene Sulfonic Acid

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PCE Tetrachloroethene

pCi/g picoCuries per gram

pCi/L picoCuries per liter

pg/L picograms per liter

PM Project Manager

PPE Personal Protection Equipment

ppm parts per million

PRG Preliminary Remediation Goals

PRP Potential Responsible Party

PSI Professional Services Industries, Inc.

PSQ Principal Study Questions

PVC Polyvinyl Chloride

QA/QC Quality Assurance/Quality Control

QAPP Quality Assurance Project Plan

R-1 Reference Area 1

R-2 Reference Area 2

RAGS Risk Assessment Guidance for Superfund

RI Remedial Investigation

RRD Remediation and Redevelopment Division

RSCC Regional Sample Control Center

SCEM Site Conceptual Exposure Model

SLERA Screening Level Ecological Risk Assessment

SMI Source Migration Investigation

SOP Standard Operating Practices

Southwest Southwest Laboratory of Oklahoma

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SOW Scope of Work

SP Self Potential

STL Severn Trent Laboratories

SVIAI Soil Volatilization to Indoor Air Inhalation

SVOC Semi-Volatile Organic Compound

SW Stilling Well

T-IR Thermal Infrared

TCE Trichloroethene

TCRA Time Critical Removal Action

TEF Toxicity Equivalence Factor

TINOPAL TINOPAL CBS-X

Tri-Matrix Tri-Matrix Laboratories, Inc.

TRIS Tris (2,3-Dibromopropyl) Phosphate

TRVs Toxicity Reference Values

TU Tritium Unit

U.S. EPA United States Environmental Protection Agency

USDA United States Department of Agriculture

USGS United States Geologic Survey

UV Ultraviolet

V Linear Groundwater Velocity

VAS Vertical Aquifer Sampling

Velsicol Velsicol Chemical Corporation

VOC Volatile Organic Compound

WTP Water Treatment Plant

WESTON® Weston Solutions of Michigan, Inc.

25


EXECUTIVE SUMMARY

ES-1

ES final rev 11-06.doc 3/9/2009

EXECUTIVE SUMMARY Weston Solutions of Michigan, Inc. (WESTON®) has prepared this Remedial

Investigation (RI) Report for Operable Unit One (OU-1) of the former Velsicol Chemical

Corporation (Velsicol) Site located in at 500 Bankson Street, St. Louis, Gratiot County,

Michigan. For the purposes of this report the Site (OU-1) is defined as the Former Plant

Site, the Former Burn Area, and the adjacent or nearby properties. This work was

completed at the request of the Michigan Department of Environmental Quality (MDEQ),

Environmental Response Division (ERD) (now the Remediation and Redevelopment

Division [RRD], Superfund Section), under the Federal Level of Effort contract between

the State of Michigan and WESTON (Contract No. 2012).

The RI objectives were to confirm the presence of releases from the Site, evaluate the

nature and extent of contamination originating from the Site, assess the fate and transport

of contaminants, and evaluate potential risk to human health and the environment at the

Site.

The primary activities conducted to accomplish the RI objectives included: soil and

groundwater sampling to define the nature and extent of contaminants of potential

concern (COPCs) and aqueous and non-aqueous phase liquids (NAPL); groundwater

monitoring to evaluate groundwater flow within the shallow outwash unit water-

producing intervals, till unit water-bearing intervals, and lower outwash unit water-

producing intervals; a slurry wall investigation to evaluate groundwater flow and

contaminant migration through the till unit and slurry wall; preparation of a Human

Health Risk Assessment (HHRA) and Ecological Risk Assessment (ERA); collection of

active soil gas samples to supplement the HHRA data set; and collection of surface soil

samples in the residential areas east and south of the Former Plant Site to evaluate the

nature and extent of pesticide contamination.

The Former Plant Site encompasses approximately 50 acres and is bordered on the west

and north by the Pine River (St. Louis Reservoir). The Former Plant Site has been used

26


EXECUTIVE SUMMARY

ES-2


for industrial operations since the mid-1800s, including a lumber mill, oil refinery, salt

plant, and chemical plant. Products produced included various salts, magnesium oxide,

rare earth (radioactive) chemicals, fire retardants (polybrominated biphenyls [PBB]), and

pesticides (hexabromobenzene [HBB], dichlorodiphenyl trichloroethane [DDT], and tris

(2,3-dibromopropyl) phosphate [TRIS]). The Velsicol plant was closed and operations

ceased in 1977.

In addition to the Former Plant Site, Velsicol operated an industrial waste burning and

disposal site (the Former Burn Area) that was located across the Pine River and to the

north of the Former Plant Site, currently within the property boundaries of the Hidden

Oaks Golf Course. The Former Burn Area accepted solid and liquid waste from the

Former Plant Site as well as solid waste from the City of St. Louis. The waste liquids

were destroyed weekly by burning in an open pit in the Former Burn Area. The Former

Burn Area was the focus of remedial activities in 1982 when approximately 68,000 cubic

yards of contaminated material was excavated by Velsicol and placed on the Former

Plant Site for disposal.

In 1982 Velsicol entered into a Consent Judgment (CJ) with the United States

Environmental Protection Agency (U.S. EPA) and MDEQ. The CJ required installation

of a 2-foot-thick, low-permeability slurry wall around the 50-acre Former Plant Site and

the installation of a cap over the area to control water infiltration. Velsicol completed

construction of the containment system in 1984.

Generally, three units of unconsolidated materials exist below the Site: a shallow outwash

unit, a till unit, and a lower outwash unit. The shallow outwash unit is a complex variety

of deposits consisting of fill, alluvium, and lacustrine deposits. However, these soils also

contain construction debris (concrete, wood, pipe,) resulting from both the operation of

and demolition of the Former Plant within the boundaries of the slurry wall. The shallow

outwash unit typically comprises the upper 20 feet (ft) of soils at the Site, but in some

areas extend to a depth of 30 ft below ground surface (bgs). The till unit is described as

sandy silt with variable amounts of sand, gravel, and cobbles. Sand and gravel seams

within the till unit range from a few inches to several feet in thickness. The thickness of

27


EXECUTIVE SUMMARY

ES-3


the till unit ranges from 30 to 80 ft. The lower outwash unit consists of interbedded sand,

gravel, silt, and clay that extends from the base of the till unit to the top of bedrock. The

elevation of the top of bedrock in the vicinity of the Site is reported to be approximately

280 ft bgs.

Groundwater flow in the shallow outwash unit water-producing intervals is influenced by

several factors, including the Pine River, the St. Louis dam, ground surface elevation, and

the presence of the slurry wall. Groundwater flow below the Former Plant Site generally

radiates outward towards the Pine River.

Groundwater flow in the lower outwash unit water-producing intervals is influenced by

several factors, including the shallow outwash unit groundwater elevations, till unit

groundwater elevations, regional flow conditions, local geology, and municipal well

usage. The primary groundwater flow directions are to the northeast in the northern

portion of the Former Plant Site and southeast in the southern portion of the Former Plant

Site in the general direction of City of St. Louis municipal water supply wells, CW-7 and

CW-8. In the Former Burn Area the groundwater flow direction is predominantly to the

southeast.

WESTON conducted soil sampling of the shallow outwash unit and conducted

groundwater gauging and sampling of the shallow outwash, till, and lower outwash units

at the Site. Groundwater samples were also collected from the City of St. Louis

Municipal water supply wells.

The soil sampling results indicate that significant contamination from volatile organic

compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, specialty

chemicals, and inorganics exists in the shallow outwash unit at the Site. Elevated

concentrations of 1,2-dichloroethane (1,2-DCA), bromomethane, and benzene were

detected in the Former Burn Area soils. Concentrations of 4,4’-DDT exceeding direct

contact (DC) criteria were detected in soil samples collected from residential properties.

The areas with the highest concentrations of contaminants and the most contaminant

detections were in the shallow outwash unit soils on the Former Plant Site.

28


EXECUTIVE SUMMARY

ES-4


The groundwater sampling results indicate that significant contamination from VOCs,

SVOCs, pesticides, specialty chemicals, and inorganics exists at the Site within the

shallow outwash unit water-producing intervals. VOCs are the predominant

contaminants present in terms of the frequency detected and the concentrations observed.

Chlorobenzene, benzene, 1,2-DCA and trichloroethylene (TCE) were the most frequently

detected and most widely dispersed VOCs on the Site. SVOCs, pesticides, and

inorganics exist, but were typically observed at fewer locations than VOCs and were

generally detected within the extent of VOC contamination in the shallow outwash unit

groundwater. VOC contamination is widespread at the Former Plant Site, with the

highest concentrations and most MDEQ criteria exceedances in the northeast and western

portions of the Former Plant Site. In addition, evidence indicates that contaminated

groundwater exceeding MDEQ criteria migrates vertically from the shallow outwash unit

into the till unit.

Groundwater within the till unit water-bearing intervals (sand seams) is contaminated

with VOCs, pesticides, and specialty chemicals at several locations on the Site. It is also

likely that significant contamination is present within the till unit in the northeast portion

of the Former Plant Site where elevated concentrations of VOCs, SVOCs, pesticides,

specialty chemicals, and inorganics were observed in the shallow outwash unit; however,

no monitoring wells are located within the till unit in this area.

The source of the contamination in the till unit water-bearing intervals is from soil and

groundwater contamination sources typically located directly above the till unit in the

unsaturated zone and in the shallow outwash unit water-producing intervals.

Contamination was detected within the till unit groundwater in the Former Burn Area;

however, concentrations are typically below MDEQ criteria.

The groundwater in the upper portion of the lower outwash unit water-producing

intervals is known to be contaminated at two locations; along the western portion of the

property (WMW-19D) and northern portion of the Former Plant Site (WMW-21D). It is

also likely that significant contamination is located in the lower outwash unit in the

northeast portion of the Former Plant Site where elevated concentrations of VOCs,

29


EXECUTIVE SUMMARY

ES-5


SVOCs, pesticides, specialty chemicals, and inorganics were observed in the shallow

outwash unit. However, no monitoring wells are located in the lower outwash unit in this

area. In addition, para-Chlorobenzene Sulfonic Acid (pCBSA) was detected in several

City of St. Louis municipal water supply wells. This indicates that there is a potential for

contamination to migrate from the Site to nearby city municipal wells.

Contamination present or suspected in the lower outwash unit in the northeastern and

western portions of the Former Plant Site appears to originate from the soils and

groundwater within the shallow outwash unit. The contaminants exceeding criteria are

typically the same as those detected in the overlying shallow outwash and till units at

these locations. The highest contaminant concentrations are generally detected in the

shallow outwash unit and progressively decrease through the till and the lower outwash

units. Contamination was detected in the lower outwash unit in the Former Burn Area;

however, the concentrations detected were below MDEQ criteria.

Concurrent with the preparation of this RI, an HHRA and an ERA were completed by

Camp, Dresser, and McKee, Inc. (CDM) through a subcontract agreement with

WESTON. The HHRA and ERA were prepared to identify and quantify risk associated

with human and ecological receptors. This risk evaluation was conducted for each

chemical group (VOCs, SVOCs, polychlorinated biphenyls [PCBs], specialty chemicals,

and inorganics) and media (soil, groundwater, surface water, air, and sediment).

The risk evaluations (HHRA and ERA) identified a significant number of chemicals of

concern (COCs), consisting of VOCs, SVOCs, pesticides, PCBs, specialty chemicals, and

inorganics, for the various media. The results of these risk evaluations indicate that

significant risks exist for human receptors and ecological receptors at the Site.

In addition to the VOCs, SVOCs, pesticides, PCBs, specialty chemicals, and inorganics,

NAPL was documented in the northeast portion of the Former Plant Site and in two

monitoring wells located at the Former Burn Area. The NAPL at the Former Plant Site

has been identified inside the containment system, outside the containment system

between the existing slurry wall and the Pine River, and in the till unit below the Pine

30


EXECUTIVE SUMMARY

ES-6


River. The NAPL is primarily composed of VOCs and pesticides including

chlorobenzene, benzene, 1,2-DCA, TCE, and DDT isomers. However, the NAPL

composition differs by location and includes other contaminants such as 1,2-dibromo-3-

chloropropane (DBCP), 1,2-dichlorobenzene, 1,4-dichlorobenzene, gamma-chlordane,

carbon tetrachloride, chloroform, 1,2-dichloropropane, and 1,4-dichloropropane.

Based on the findings and conclusions of the RI, sufficient evidence exists to support the

recommendation that remedial activities are required at the Site to mitigate the soil and

groundwater contamination present. In order to support remedial decisions for the Site, it

is recommended that a feasibility study (FS) be prepared. In addition, a pre-design

investigation should be performed to better define the current groundwater flow and

contaminant migration information, and to further characterize soil contamination due to

the risk to human health and the environment as documented in the HHRA and ERA.

31


INTRODUCTION

1-1 Section 1 final rev 11-06.doc 3/9/2009

SECTION 1

INTRODUCTION

Weston Solutions of Michigan, Inc. (WESTON®) has prepared this Remedial Investigation (RI)

Report for Operable Unit One (OU-1) of the former Velsicol Chemical Corporation (Velsicol)

Site located in St. Louis, Gratiot County, Michigan (Figure 1-1). OU-1 (the Site) is defined as

three sub-areas for the purposes of this RI Report: the Former Plant Site, the Former Burn Area,

and the adjacent or nearby properties (including residential properties, the Former Creamery

Warehouse, and Velsicol Property Number 1). The residential areas were included in the

investigation based on evidence indicating that surface soil and groundwater contamination

potentially related to the Former Plant Site existed. This work was completed at the request of

the Michigan Department of Environmental Quality (MDEQ), Environmental Response Division

(ERD) (now the Remediation and Redevelopment Division [RRD], Superfund Section), under

the federal Level of Effort contract between the State of Michigan and WESTON (Contract

No.2012). The RI was completed following MDEQ’s approval of the following documents:

Final Work Plan for the Phase I Evaluation of the Velsicol Superfund Site Slurry Wall, dated January 2002.

Work Plan for the Phase II Evaluation of the Velsicol Superfund Site, Operable Unit One, dated June 2002.

Work Plan Letter for the Phase IIB Evaluation of the Velsicol Superfund Site, Operable Unit One, dated August 2002.

Work Plan Letter for the Phase IIC Evaluation of the Velsicol Superfund Site, Operable Unit One, dated January 2003.

Work Plan Addendum for the Phase III Evaluation of the Velsicol Superfund Site, Operable Unit One, dated October 2004.

The United States Environmental Protection Agency (U.S. EPA) was also provided copies of the

Work Plans prior to or at the beginning of some work efforts for review and comments.

This RI Report presents the data collected and the conclusions drawn during the Phase I, II, IIB,

IIC, and III activities; documents any deviations in the execution of the scope from the

procedures detailed in the respective Work Plans for Phase I, II or III activities; incorporates the

32


INTRODUCTION


findings and conclusions of the Phase I and II investigation with the Phase III findings; and

provides conclusions and recommendations for the Feasibility Study (FS) to be prepared for the

Site. This RI Report presents data obtained during Phase I, II, IIB, IIC, and III and reflects a

dynamic Scope of Work (SOW). The investigation evolved to answer questions regarding the

soil cap, the slurry wall, and the Former Burn Area, and to further evaluate the nature and extent

of releases from the Site. Periods of investigative work performed at the Site are detailed below:

Phase I: January through March 2002 Phase II: July 2002 Phase IIB: September 2002 Property Transaction Geoprobe Investigation: December 2002 Phase IIC: February through March 2003 Phase III: October 2004 through October 2005

In order to clearly present the activities and findings, this RI Report consists of:

Section 1 – Introduction. Section 2 – Summary of Site Investigation Activities. Section 3 – Results. Section 4 – Risk Evaluation. Section 5 – Discussion. Section 6 – Conclusions and Recommendations. Section 7 – References.

Although the Guidance for Conducting Remedial Investigations and Feasibility Studies Under

CERCLA, dated October 1988, was used during preparation of this RI Report, some deviations

exist. The most significant deviation is the placement of the Risk Evaluation section after

presentation of the investigation results rather than after the recommended section, Contaminant

Fate and Transport. This decision was made to support the description of the risk assessment

process, beginning with selection of contaminants of potential concern (COPCs) through

development of contaminants of concern (COCs).

1.1 PROJECT SCOPE AND OBJECTIVES

1.1.1 Purpose and Scope of Project

The information obtained and conclusions reached during completion of the RI will facilitate the

development of a FS that will be used to support a Record of Decision for OU-1. Operable Unit

33


INTRODUCTION


Two (OU-2) consists of contamination in sediments and biota in the St. Louis Reservoir and the

Pine River; U.S. EPA is currently managing sediment removal in OU-2, which is not part of this

RI.

The scope of the project includes RI activities at or associated with OU-1. The investigative

activities included the completion of sampling at nearby or adjacent properties that were at one

time owned by Velsicol, including the Former Creamery Warehouse, the Former Burn Area,

Former Velsicol Parking Lot, and Velsicol Property Number 1. The approximate boundaries of

these properties are shown in Figure 1-2. Investigative results obtained for the Former Creamery

Warehouse, the Former Burn Area, and Velsicol Property Number 1 are discussed as they are

related to contamination originating from the Site.

1.1.2 RI Objectives

The overall RI objectives are to confirm the presence of releases from the Site, evaluate the

nature and extent of contamination originating from the Site, evaluate potential environmental

impacts of the Former Plant Site and Former Burn Area properties, and assess the fate and

transport of contaminants. A phased approach, described below, was used to accomplish these

objectives. The data generated, evaluated, and interpreted for each phase of work was used in the

development of subsequent phases of work.

The primary objectives of the Phase I RI activities were as follows:

Locate the slurry wall.

Characterize the soil and groundwater chemistry immediately inside and outside of the slurry wall.

Provide an initial evaluation regarding the integrity of the slurry wall.

The primary objectives of the Phase II site investigation were as follows:

Further evaluate the effectiveness of the existing containment system components (i.e., slurry wall and underlying till unit) related to ongoing releases from the Former Plant Site.

Define the nature and extent of COPCs, including aqueous and non-aqueous phase liquids (NAPL) along the perimeter of the Former Plant Site.

34


INTRODUCTION


Evaluate the hydraulic conductivity of the slurry wall and till unit at Former Plant Site using water and Site NAPL samples.

Evaluate groundwater flow and water quality within the shallow and lower outwash unit water-producing intervals, and groundwater/contaminant flow through the till unit and slurry wall.

Assess the interaction of precipitation, groundwater, and surface water in the Pine River.

The primary objectives of the Phase IIB site investigation were as follows:

Determine the vertical and horizontal extent of COPCs, including dissolved contamination and NAPL (if present) identified during the Phase I and II investigation activities within the shallow and lower outwash unit water-producing intervals at OU-1.

Evaluate groundwater flow and hydrogeologic properties within the shallow and lower outwash unit water-producing intervals at OU-1 and immediately across the Pine River.

The primary objectives of the Phase IIC site investigation were as follows:

Obtain further information regarding groundwater flow in the shallow and lower outwash unit water-producing intervals.

Obtain additional groundwater chemistry data east and south of the Former Plant Site.

The primary objectives of the Phase III site investigation were as follows:

Determine the nature and extent of soil and groundwater contamination at the Former Burn Area, if present, in the shallow outwash unit water-producing intervals, till unit water-bearing intervals, and the upper portion of the lower outwash unit water-producing intervals.

Collect and analyze soil gas (methane screening) and shallow soil samples from OU-1 for use in the preparation of a Site Ecological Risk Assessment (ERA) and Human Health Risk Assessment (HHRA).

Conduct a soil and groundwater investigation of the shallow outwash unit at OU-1.

Characterize the till unit water-bearing intervals and the lower outwash unit water-producing intervals at OU-1.

Evaluate possible contaminant migration within the shallow outwash unit water-producing intervals, till unit water-bearing intervals, and lower outwash unit water-producing intervals towards the residential area east of OU-1.

During the evaluation of Phase III data collected by U.S. EPA and MDEQ, additional tasks were identified. These included:

35


INTRODUCTION


Collect perimeter soil and groundwater samples outside the slurry wall.

Collect active soil gas samples to supplement the HHRA.

Collect surface soil samples in the residential areas east and south of the Site to evaluate the nature and extent of pesticide contamination.

In addition to the above activities, a Property Transaction Geoprobe Investigation was conducted

on the four parcels owned by the Velsicol Custodial Trust. These parcels were either located on

the Former Plant Site that were not highly developed (M-46 Corridor and the former Research

and Development Area) or parcels in the nearby or adjacent properties that were used by

Velsicol for ancillary operations (Former Creamery Warehouse and Velsicol Property Number

1). The primary objectives of the Property Transaction Geoprobe Investigation were to evaluate

potential environmental impacts to soil and/or groundwater at these various parcels as described

in WESTON’s Property Transaction Geoprobe Investigation Report, dated 4 August 2003.

1.2 SITE INFORMATION

1.2.1 Site Location

The Former Plant Site is located at 500 Bankson Street, St. Louis, Gratiot County, Michigan.

The property is located near the center of Section 24, Township 12 North, Range 3 West

(Figure 1-1). The Former Plant Site encompasses approximately 50 acres and is bordered on the

west and north by the Pine River (St. Louis Reservoir); on the east by Watson Street; and on the

south by Washington Avenue and North Street. For the RI, the boundary of the Former Plant

Site adjacent to the river is considered to be the edge of the Pine River. Velsicol operations were

also conducted on three nearby parcels (the Former Creamery Warehouse, Former Burn Area,

and Velsicol Property Number 1). These properties were included in the Site investigation and

have been included in the sub-group “adjacent or nearby properties” along with the residential

properties to the south and east of the Former Plant Site. The Former Creamery Warehouse is

located south of the Former Plant Site and Washington Avenue (M-46), the Former Burn Area is

located north of the Former Plant Site across the Pine River within the boundaries of the Hidden

Oaks Golf Course, and Velsicol Property Number 1 was used as a parking lot located south of

the main entrance at North and Bankson Streets. Figure 1-2 shows the Former Plant Site

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boundaries, approximate boundaries of the Former Creamery Warehouse, the Former Burn Area,

Velsicol Property Number 1 parcels, and current Site layout.

1.2.2 Site History

The Former Plant Site had been used for industrial operations since the mid-1800s, including a

lumber mill, oil refinery, salt plant, and chemical plant. Michigan Chemical Corporation (MCC)

purchased the Former Plant Site in 1935 and operated a chemical manufacturing business until

1977, when MCC merged with Velsicol. MCC manufactured a wide variety of products at the

Former Plant Site from 1936 through 1977. These products included various salts, magnesium

oxide, rare earth (radioactive) chemicals, fire retardants (polybrominated biphenyls [PBB]), and

pesticides (hexabromobenzene [HBB], 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane or

dichlorodiphenyl trichloroethane [DDT], and tris (2,3-dibromopropyl) phosphate [TRIS]).

Former Plant Site features included numerous manufacturing plant buildings, maintenance and

warehouse buildings, offices, research and development laboratories, dozens of aboveground

storage tanks, underground storage tanks, process piping, railroad sidings, lagoons, and parking

areas (Figure 1-3). While many of the raw materials for the chemical manufacturing operations

were shipped to the Former Plant Site via rail or truck, brines were also extracted for use as

process makeup water from two bedrock wells on and near the Former Plant Site

(Subsection 1.3.5.3). The exact locations of these deep wells, with the exception of well 13, are

not known, nor is it known if they were ever used for re-injection. The possible location of well

13 is shown on Figure 1-3 in the northern portion of the Former Plant Site; however, it is not

known if this well was ever used for re-injection. The plant was closed in 1977 and

decommissioning activities were initiated in 1978.

Velsicol operated an industrial waste burning and disposal site (the Former Burn Area) that was

located on the Hidden Oaks Golf Course, across the Pine River from the Former Plant Site. The

Former Burn Area accepted solid and liquid waste from the Former Plant Site as well as solid

waste from the City of St. Louis. The waste liquids were destroyed weekly by burning in an

open pit in the Former Burn Area. The Former Burn Area was the focus of previous

investigative and remedial work resulting in the removal of approximately 68,000 cubic yards of

contaminated material in 1982. This work was performed by Velsicol under state and federal

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oversight. This material was moved to the Former Plant Site, spread on the property, and buried

beneath a soil cap (described below). A full description of this work is contained in the Final

Report, Summary of Remedial Action, Securement of Waste Burning and Disposal Area, Golf

Course Site, dated August 1982, prepared by Conestoga-Rovers and Associates Limited (CRA).

Velsicol disposed of groundwater recovered during previous remedial actions conducted at the

Former Plant Site by injecting the water into a deep well previously located on the Crumbaugh

property. The exact location of the injection well has not been identified. The Crumbaugh

property is located across the Pine River from the Former Plant Site and is adjacent to the

Hidden Oaks Golf Course.

In 1982, a Consent Judgment (CJ) was entered into by Velsicol, the U.S. EPA, and the Michigan

Department of Natural Resources (MDNR) now known as the MDEQ. Under the CJ, Velsicol

constructed and implemented the “Main Plant Site Containment Program and Golf Course Site

Remedial Program.” Between 1981 and 1984 and in accordance with the CJ, Velsicol submitted

plans and specifications for the construction and installation of a containment system at the

Former Plant Site for U.S. EPA and MDNR review and approval. During the development of

these plans and specifications, Velsicol conducted field sampling and laboratory-testing

programs in accordance with the CJ to confirm that the construction specifications established

for the components of the containment system would be met. The results of these sampling and

laboratory programs were reviewed and approved by the U.S. EPA and MDNR as the design

progressed.

The remedy selected and implemented for the Former Plant Site generally consisted of isolating

the area by installation of a 2-foot thick, low-permeability slurry wall around the 50-acre main

plant facility and the installation of a cap (18 to 36 inches in thickness) over the area to control

water infiltration. Under the CJ, Velsicol was required to maintain groundwater levels within the

slurry wall and beneath the cap (“containment system”) to a maximum allowable elevation.

Velsicol completed construction of the containment system in 1984.

Construction of the containment system included the following:

Placement along the entire boundary of the Former Plant Site of a continuous containment wall that was reportedly keyed a minimum of 30 inches into the underlying

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clay till unit and that was to achieve a permeability of 1 x 10-7 centimeters per second (cm/s).

Construction of a cap 36 inches (18 inches in some areas) thick over the Former Plant Site and compacted to achieve a permeability of 1 x 10-7 cm/s.

Maintenance of the water table elevation within the containment system to no greater than 724.13 feet (ft) above mean sea level (msl), as calculated from the average water table elevations of 14 monitoring wells located on the Former Plant Site.

The CJ also provided for periodic testing of the containment wall for 3 years after its installation.

During the implementation of the Former Plant Site closure program in 1983 and 1984, Velsicol

was required to conduct a comprehensive quality assurance/quality control (QA/QC) sampling

program to monitor the installation of the various components of the containment system.

QA/QC samples were collected and evaluated to ensure that the construction specifications

established within the CJ would be met. According to the March 1984 QA/QC Testing

Containment Wall Construction Report prepared by CRA for Velsicol, the containment system

components were installed according to the specifications set forth in the CJ.

All of the tasks outlined within the CJ were completed by 1986 under state and federal oversight.

The Former Plant Site was then subject to an Operation and Maintenance (O&M) Program

prepared by Velsicol and approved by U.S. EPA and MDNR (now MDEQ). The O&M program

was implemented after state and federal review. According to the Summary of Post-Construction

Containment Wall Monitoring December 1983 to September 1986, prepared by CRA for

Velsicol, subsequent periodic testing in the 3 years following construction of the containment

system indicated the system was constructed as designed.

Water levels inside the containment system (slurry wall and cap) were maintained below the

level set by the CJ through 1998. Maintenance of the water levels was accomplished, in part, by

the extraction of groundwater (i.e., 1.25 million gallons in 1993 and 1.28 million gallons in

1994). The majority of the extracted groundwater was injected in the off-site Crumbaugh deep

injection well with some of the water transported to the City of St. Louis Waste Water Treatment

Plant. Extraction of groundwater from the containment area was stopped after the Crumbaugh

injection well could no longer be used.

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Due to increasing water levels within the containment system in 1993, U.S. EPA and MDEQ

became concerned about what effect, if any, the water levels might have upon the integrity of the

containment system. Because of these concerns, Velsicol agreed to assess the effectiveness of

the conta

REMEDIAL INVESTIGATION REPORT FOR OPERABLE ...W.O. No.: 20083.500.006 1 Remedial Investigation...

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