Mesquite Regional Landfill | Projects

Verdantas performed extensive geotechnical characterization, master planning, materials evaluations, technical design reporting, and final cover engineering for the 2,300‑acre, 600‑million‑ton Mesquite Regional Landfill. This mega‑landfill, designed for waste‑by‑rail operations, required large‑scale subsurface investigations, complex material sourcing studies, and the development of technical documents to support regulatory permitting and long‑term operational design.

Geotechnical Characterization & Master Plan Development

Verdantas conducted one of the most comprehensive geotechnical investigations performed for a West Coast landfill project, including:

167 borings totaling 10,265 linear feet
244 test pits for Master Plan phase design and materials sourcing
Detailed subsurface profiling for future cell development and performance modeling

Master Plan work addressed:

Cell sequencing and development
Liner and leachate collection and removal system (LCRS) design
Stockpile and soil/borrow management
Waste and soil handling processes
Intermediate and final cover systems
Drainage facilities
Landfill gas collection systems
Liquids collection and treatment infrastructure
Rail yard, intermodal facility, access roads, maintenance facilities, and support buildings

Clay Resources Evaluation

Verdantas evaluated both stockpile and in situ clay sources, including:

69 borings up to 100 feet deep
18 test pits for sampling and evaluation
Laboratory hydraulic conductivity testing (ASTM D5084)
Geophysical surveys (resistivity & seismic refraction) to delineate clay limits and estimate rippability

Findings included:

2.2 million cubic yards of suitable clay in stockpiles
15.2 million cubic yards in in situ deposits
Blending and processing recommendations to optimize liner material yield

Sand & Gravel Deposit Evaluations

To support LCRS gravel, road base, concrete aggregate, and LFG trench backfill needs, Verdantas excavated:

51 bucket‑auger borings
47 test pits
24 large‑diameter ring density tests

Material assessments included:

Gradation of coarse materials up to 8 inches
Aggregate quality (soundness, abrasion, petrographic analysis, reactivity)
In situ compressibility under 450 feet of refuse loading
Screening and washing plant sizing and processing yield estimates

Mine Waste & Heap Leach Pad Characterization

Verdantas evaluated:

113.6 million cubic yards of mine‑run material
97.8 million cubic yards of heap‑leach material

This included:

36 borings (1,617 linear feet)
166 test pits
Sonic drilling, gradation testing, and aggregate quality analyses

These materials were examined for use in cover systems, structural fill, and facility construction.

Infrastructure Foundation Engineering

Verdantas provided grading and foundation recommendations for:

Rail spur and intermodal yard
Weigh scales
Administrative, service, and maintenance buildings

Seismic design values were established based on regional seismicity and site investigations.

Technical Memoranda & Technical Design Report (TDR)

Verdantas prepared detailed Technical Memoranda covering every major investigation component, forming the technical foundation for the landfill’s Master Plan.

A full Technical Design Report (TDR) was prepared to secure regulatory approval for the first 8‑acre composite liner cell, including:

LCRS design and equivalency demonstration
Vadose zone monitoring evaluations
Surface drainage design
Alternative cover evaluations

Submitted to:

RWQCB (Colorado River Basin Region)
CIWMB
California DWR

Alternative Final Cover Study

Verdantas led an advanced cover system evaluation intended to replace the approved geosynthetic‑resistive barrier top deck with an evapotranspirative (ET) monocover.

Work included:

Field investigation of stockpiles, leach pads, and alluvial deposits
Laboratory reconstitution of samples to representative gradations
Unsaturated flow modeling for cover percolation
Static and seismic veneer stability analysis
Erosion resistance evaluations

The study permitted the use of large‑size (up to 12‑inch) material for side‑slope cover—a key innovation that received high professional praise and client commendation.

Solution

Engineering

Environmental Science

Expertise

Hydrology, Hydraulics, & Fluids

Natural Resources & Environmental Planning

Site & Roadway Civil Engineering

Geotechnical & Geological Engineering

Environmental Assessment & Remediation

Structural Engineering

Market

Government