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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
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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)
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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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TABLE OF CONTENTS (Cont’d)
VOLUME I OF VIII
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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TABLE OF CONTENTS (Cont’d)
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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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TABLE OF CONTENTS (Cont’d)
VOLUME I OF VIII
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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LIST OF FIGURES (Cont’d)
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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LIST OF FIGURES (Cont’d)
VOLUME V OF VIII
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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LIST OF FIGURES (Cont’d)
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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LIST OF FIGURES (Cont’d)
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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LIST OF FIGURES (Cont’d)
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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GLOSSARY OR ACRONYMS AND ABBREVIATIONS (Cont’d)
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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GLOSSARY OR ACRONYMS AND ABBREVIATIONS (Cont’d)
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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GLOSSARY OR ACRONYMS AND ABBREVIATIONS (Cont’d)
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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GLOSSARY OR ACRONYMS AND ABBREVIATIONS (Cont’d)
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.
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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
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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
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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.
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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,
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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
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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.
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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
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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
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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.
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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:
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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