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Implementing Advanced Site Characterization Tools

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About ITRC
Navigating this Website
1 Introduction
1 Introduction Overview
1.1 Purpose and Scope
1.2 Technologies
1.3 How to Use this Document
2 ASCT Implementation
2 ASCT Implementation Overview
2.1 Tool Selection
2.2 Tool Application
3 Direct Sensing
3 Direct Sensing Overview
3.1 How to Select and Apply Direct Sensing Tools Using this Document
3.2 Membrane Interface Probe
3.3 Optical Image Profiler
3.4 Laser-Induced Fluorescence
3.5 Cone Penetrometer Testing
3.6 Hydraulic and Groundwater Profiling Tools
3.7 Electrical Conductivity (EC) Probe
3.8 Flexible Liners
4 Borehole Geophysics
4 Borehole Geophysics Overview
4.1 How to Select and Apply Borehole Geophysical Tools Using this Document
4.2 Fluid Temperature
4.3 Fluid Resistivity
4.4 Mechanical Caliper
4.5 Optical Televiewer
4.6 Acoustic Televiewer
4.7 Natural Gamma Logging
4.8 Borehole Flow Meters
4.9 Advanced Borehole Logging Tools
5 Surface Geophysics
5 Surface Geophysics Overview
5.1 How to Select and Apply Surface Geophysical Tools Using this Document
5.2 Electrical Resistivity Imaging
5.3 Ground Penetrating Radar
5.4 Seismic Methods
5.5 Electromagnetic Surveys
6 Remote Sensing
6 Remote Sensing Overview
6.1 How to Select and Apply Remote Sensing Tools Using this Document
6.2 Drones
6.3 Visible Spectrum Camera
6.4 Camera Features
6.5 Photogrammetry
6.6 Sample Collection and Monitoring using Drones
6.7 Cost Considerations
6.8 Case Studies
7 Stakeholder and Tribal Perspectives
8 Regulatory Perspective
8 Regulatory Perspective Overview
8.1 Challenges and Solutions
9 Case Studies
9 Case Studies Overview
9.1 MIP Boring Data Allow On-Site Decisions to Fill Data Gaps and Reduce Uncertainty during Triad Approach Evaluation at Five South Dakota Sites
9.2 MIP Allows Real-Time Identification and Delineation of DNAPL Plume at a Former Naval Air Station in California
9.3 OIP-Green Probe Delineates Extent of Coal Tar NAPL at a Former Gas Manufacturing Plant in Kansas
9.4 LIF Survey with UOVOST® Provides More Accurate Representation of LNAPL Plume at a Former Bulk Petroleum Storage Facility in New Hampshire
9.5 UVOST Differentiates LNAPL Types to Allocate Financial Liabilities at a Retail Petroleum Facility in Tennessee
9.6 TarGOST Determines DNAPL Extent and HPT Confirms Site Lithology at a Former Creosote Facility in Louisiana
9.7 CPT Borings and Hydropunch Sampler Optimize Site Characterization at an Aviation Industrial Complex in California
9.8 Waterloo APS, CPT, and LIF Data Update CSM and Help Optimize Selected Remedy at a Former Refinery in Oklahoma
9.9 Conceptual Site Model Development Using Borehole Geophysics at the Savage Municipal Water Supply Superfund Site in New Hampshire
9.10 ERI Provides Data to Improve Groundwater Flow and Contaminant Transport Models at Hanford 300 Facility in Washington
9.11 Surface and Borehole Geophysical Technologies Provide Data to Pinpoint and Characterize Karst Features at a Former Retail Petroleum Facility in Kentucky
9.12 GPR Data Show Location of Buried Debris and Piping Associated with a Former Gas Holder in Minnesota
9.13 Resistivity, Seismic Exploration, and GPR Provide Data to Evaluate Clay Reserves at a Commercially Mined Pit
9.14 Seismic Refraction, Electric Resistivity, and Multichannel Analysis of Seismic Waves Provide Data to Locate Monitoring Well Locations in a Mixed-Use Area in Northern Virginia
9.15 Surface Geophysical Methods Provide Data to Identify Prospective Utility Waste Landfill Sites in Karst Terrain in Missouri
9.16 Airborne Time-Domain Electromagnetic Method Maps Sand Distribution along the Illinois Lake Michigan Shore
9.17 Drone Technology Expedites and Streamlines Site Characterization at a Former Golf Course in Missouri
9.18 High-Resolution and Thermal Aerial Images Identify Mine Openings at an Abandoned Colorado Mine
9.19 RPAS Collects Water Samples to Avoid Safety Concerns at Montana Tunnels Mine
Additional Information
Appendix A. Tool Tables and Checklists
Glossary
References
Acronyms
Acknowledgments
Team Contacts
Document Feedback

 

Click for Selection Tool Click for Summary Tables Click for Tool Descriptions Click for Case Studies Click for Checklists Click for Training Videos Click for Home

9.12 GPR Data Show Location of Buried Debris and Piping Associated with a Former Gas Holder in Minnesota

Jennifer Jevnisek
Minnesota Pollution Control Agency
St. Paul, MN
[email protected]

In 2014, the City of Duluth formally enrolled a vacant city lot in the state’s Voluntary Remediation Program. The site, which was planned for redevelopment, is located on a 3.10-acre vacant lot northwest of the intersection of Jay Street and 41st Ave in Duluth, Minnesota (see Figure 9‑42).

Figure 9‑42. Site location of former gas holder in Duluth, MN.

A Phase I Environmental Site Assessment (ESA) (BayWest 2013) noted that the site was previously occupied with a gas holder (a facility used to provide storage in connection with manufactured gas plants). The gas holder was on-site from approximately 1923 until 1960 when the facility was demolished and the associated equipment may have been partially buried on site. Historical documents indicate that the location of the actual manufacturing gas plant site was located miles away. Exact building specifications and demolition information of the gas holder are unknown.

A Phase II ESA, conducted to prepare a Response Action Plan (RAP) for the project, noted that site geology consists primarily of sand and gravel with layers of silty sand, sandy silt, silty clay, and silt. The report also noted that bedrock was not encountered in borings placed as deep as 20 ft below ground surface. Investigation work encountered groundwater at depths ranging from 3 ft to 17 ft below ground surface.

In October 2013, a site reconnaissance was conducted as part of due diligence efforts. (BayWest 2013) noted building debris in the wooded area directly north of a former boiler and an area of elevated ground surface consistent with the description of where chimney debris associated with the former gas holder would have been buried. Because the extent of buried debris and demolition material was unknown, a limited GPR investigation (see Figure 9‑43) was conducted in November 2013 to assess the location of this material. GPR was selected based on its ability to noninvasively provide images of man-made objects in the near subsurface.

Figure 9‑43. GPR investigation area, as presented in report from contractor.

Scans were collected with the GPR unit in parallel lines approximately 3 ft on center. The GPR unit was able to detect to approximately 4 ft below ground surface. The assessment revealed two locations with possible buried debris at depths of 2 ft to 4 ft below ground surface (see Figure 9‑44 and Figure 9‑45) near test pits TP-03 and TP-06 (see Figure 9‑42 for test pit locations). The data images in Figure 9‑45 for TP-06 were from scans performed just east of the former boiler room. The GPR equipment consistently picked up images of either fill material or disturbed soil in this area. The cost of this assessment was $3,200.

Figure 9‑44. GPR scan and input from GPR contractor. Location pertains to TP-03.

Figure 9‑45. GPR scan near TP-06 (see Figure 9‑42 for location of TP-06).

A subsequent test pit investigation was performed in January 2014 to confirm the findings of the GPR assessment (BayWest 2014). The investigation confirmed the presence of debris at TP-03 at a depth of 2 ft to 6 ft below ground surface. The GPR assessment also identified a pipe connecting the former gas holder to the former boiler at approximately 2 ft to 2.5 ft below ground surface (see Figure 9‑46); its presence was confirmed at test pit TP-02 where it was encountered at approximately 2 ft below ground surface.

Figure 9‑46. GPR scan and photo near TP-02 (see Figure 9‑42 for location of TP-02).

Data obtained from the GPR assessment and test pit excavation were used in conjunction with supplemental soil and groundwater data to develop a RAP, (BayWest 2016). Response actions included soil stabilization, excavation, and disposal, removal of concrete and asbestos containing material, and the removal of debris comingled with soil (BayWest 2016).

The city representative noted that while the tool was effective at identifying features in the survey area, a significant amount of material had been overlooked and was discovered during redevelopment (BayWest 2016). The suspicion was that overlooked material was not due to technology failure, but because a portion of the site had not been investigated with the tool. The discovery of overlooked material and associated costs resulted in project overruns and a fair amount of bad will among project stakeholders.

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