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Underground Mine Engineering

Mine Subsidence
Investigation &
Mitigation

Western-EGI is one of one of Wyoming's most experienced firms in abandoned mine subsidence investigation and mitigation support — with continuous engagement since 2015 as a subconsultant on Wyoming's largest active AML program, and a decade of forensic subsidence work across the state.

10+
Years AML Program Experience
$40M+
AML Programs Supported
2015
AML 17.6 — Continuous Since
Our Process Technical Expertise Forensic & Litigation Representative Projects
Western-EGI drill crew on subsidence investigation
Mine Subsidence Investigation · Southwest Wyoming
End-to-End Delivery

From Archive to
As-Built

Mine subsidence mitigation is not a single service — it is a multi-phase engineering program requiring specialized knowledge at every step. Western-EGI has provided technical services across every phase of this process, from single-site forensic investigations to multi-year, multi-contract AML programs.

01

Mine Map Research & Archival Investigation

Comprehensive research of historical mine records, MSHA archives, WDEQ/AML databases, and proprietary mapping to establish the three-dimensional geometry of underground workings. The quality of this work determines the efficiency of every subsequent phase — and it is where Western-EGI's regional knowledge is most valuable.

02

Exploratory Drilling & Geophysical Logging

Strategic borehole siting, drilling coordination, electronic log (e-log) interpretation, and void characterization. Western-EGI designs exploration programs for maximum information yield at minimum cost — drawing on a decade of regional experience interpreting subsurface conditions across Wyoming's coal and evaporite sequences.

03

Grout Mix Design & Laboratory Testing

Western-EGI developed flyash grout alternative mixes for the AML 17.6 series — innovations that reduced material costs without compromising structural performance. All grout mixes are designed and tested in our AASHTO-certified Rock Springs laboratory before field deployment.

04

Production Drilling & Grouting Operations

Technical inspection and QC support for grouting operations: borehole layout review, grout plant monitoring, injection pressure observation, grout take records, and field reporting. Western-EGI provides inspection and technical services during production drilling and grouting programs managed by the prime contractor.

05

As-Built Documentation & Regulatory Reporting

Comprehensive as-built records, grout take summaries, borehole logs, closure reports, and regulatory submittals fully compliant with WDEQ/AML requirements. Western-EGI has supported program-close documentation on multiple state and federal subsidence programs.

$132M+
AML 17.6 Series — Wyoming's largest active subsidence mitigation program. Western-EGI has provided technical inspection and support services since 2015 as a subconsultant to BRS Inc.

Technical Service Scope

Western-EGI provides technical services across the full range of subsidence program phases — from archival research and forensic investigation through inspection, lab testing, and regulatory support.

  • Mine map research & archival investigation
  • Borehole siting & exploratory drilling coordination
  • E-log interpretation & void characterization
  • Grout mix design & laboratory testing
  • Flyash alternative development
  • Production drilling inspection & QC support
  • Grout take records & pressure monitoring
  • WDEQ/AML regulatory submittals
  • As-built documentation
  • Forensic investigation & litigation support

WDEQ/AML Contract History

Western-EGI holds an established working relationship with Wyoming's Abandoned Mine Lands program, serving as a subconsultant on multiple MOMSAO, MOMSAO-II, and WMSIP contract vehicles. Our principals have worked directly with WDEQ/AML program staff for over a decade — a relationship that accelerates approvals and reduces administrative friction on every program.

What Sets Us Apart

No Other Firm in Wyoming
Brings This Depth.

Subsidence mitigation requires a rare combination of geotechnical engineering, geology, drilling engineering, laboratory science, and regulatory knowledge. Western-EGI has built this capability through more than a decade of continuous involvement in Wyoming AML programs and forensic subsidence investigations.

🗺️
Mine Map Interpretation
Decades of archived records, inconsistent coordinate systems, partial surveys, and undocumented workings — our team has navigated all of it. Accurate mine geometry reconstruction is the foundation of every sound mitigation program.
🧪
In-House Grout Testing
Our AASHTO-certified laboratory designs and tests grout mixes before they go into the ground. Western-EGI developed flyash grout alternatives that reduced material cost on the AML 17.6 series without compromising structural performance.
📡
E-Log Interpretation
Electronic geophysical logging of boreholes provides critical data on void locations, fill quality, and subsurface conditions. Our geologist and engineers have interpreted e-logs on dozens of subsidence boreholes — building a regional pattern library no other firm possesses.
🏛️
WDEQ/AML Regulatory Knowledge
Wyoming's AML program has specific documentation, submittal, and reporting requirements that differ from standard geotechnical practice. Our decade of AML contract history means we know exactly what the program requires — reducing revision cycles and accelerating approvals.
💡
Grout Alternative Innovation
Conventional cement-based grouts are often expensive and not always the best technical solution. Western-EGI has innovated flyash-based alternative mixes — developed and tested in our lab — that deliver cost savings to program owners without sacrificing performance.
⚖️
Forensic & Expert Testimony
When subsidence causes property damage and litigation follows, Western-EGI principals have served as expert witnesses and provided litigation-grade technical analysis in complex cases involving multiple parties, regulatory agencies, and legal counsel.
Beyond Mitigation

Forensic Investigation
& Litigation Support

When subsidence causes damage — to homes, infrastructure, or public land — the engineering questions become legal questions. Western-EGI has the technical depth and expert witness experience to support counsel, insurers, and government agencies through the most complex subsidence disputes.

Forensic subsidence work demands a different kind of rigor than mitigation engineering. Data must be collected and documented to litigation standards. Technical opinions must be defensible under cross-examination. Reports must communicate complex geotechnical concepts clearly to non-technical audiences — judges, juries, and insurance adjusters.

Western-EGI's principals have provided expert testimony and technical analysis in subsidence cases involving abandoned coal mines, gypsum mines, and other underground workings — across multiple states, with damage claims ranging from individual property losses to multi-party class action contexts.

Our in-house laboratory capability is particularly valuable in forensic work: samples can be tested, results documented, and chain-of-custody maintained entirely within our organization — with no third-party lab introducing questions about handling or methodology.

150+

Homes — Hideaway Hills Forensic Investigation

Western-EGI has been retained since 2020 to provide forensic subsidence investigation and litigation support for a case involving 150+ residential homes affected by surface collapse over an abandoned gypsum mine in Blackhawk, South Dakota. The project involves multi-party litigation, ongoing site monitoring, and expert technical analysis. Client: Fox Rothschild LLP (Kathleen Barrow). Estimated impact: ~$34M.

Rock core boxes Drill crew operation Soil sample liner
Selected Work

Representative
Subsidence Projects

Wyoming AML — Engineer of Record — Ongoing
$132M+
AML 17.6 Series — Wyoming's Largest Active Subsidence Program
Western-EGI has served as a subconsultant to BRS Inc. on the AML 17.6B, C, and D contracts since 2015 — Wyoming's largest active subsidence mitigation program. Western-EGI's services include mine map research, exploratory drilling support and coordination, flyash grout alternative development, grout mix design and testing, field inspection, e-log interpretation, and technical reporting. Continuous engagement now spanning over a decade. Client: BRS Engineering (Harold Hutson).
10+
Drill & Grout Projects
$40M+
Total Subsidence Portfolio
2015
Continuous Since
Ongoing
Active Program Status
Forensic — Gypsum Mine — Ongoing
~$34M
Hideaway Hills — Blackhawk, SD
Forensic subsidence investigation and litigation support involving 150+ homes above an abandoned gypsum mine. Expert analysis, ongoing site monitoring, and technical reporting in support of complex multi-party litigation. Client: Fox Rothschild LLP (Kathleen Barrow). Active since 2020.
Wyoming AML — Active
~$3M
AML 68-NC
Abandoned mine lands subsidence mitigation project under Wyoming's AML program. Western-EGI providing engineering and field services. Active since 2024.
Wyoming AML — WMSIP
~$400K
AML Wyoming Mine Subsidence Investigation Program
WMSIP contract — geotechnical investigation, subsurface characterization, and mitigation engineering under Wyoming's statewide AML framework. Active since 2024.

Facing a Subsidence
Challenge?

Whether you need forensic investigation, technical inspection support for an active AML program, or litigation support — Western-EGI has the regional experience, laboratory capability, and regulatory familiarity to deliver. Contact Rob Gerrard, PE to discuss your project.

Email Rob Gerrard, PE Call (307) 362-5180