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Underground Rock Mechanics Aessessment Project

Battle Mountain, Nevada

Echo Bay Minerals Company

WSMC made an assessment of the underground mining feasibility of a small high grade vein in an existing pit wall. The assessment was made primarily from a rock mechanic perspective. A review of geologic information, and cores from the target zone was conducted to determine preliminary rock parameters. Recommendations for rock support, and opening designs were made based on these results. A review of several proposed mining plans was also done for rock mechanics compatibility. Sources of aggregate for backfill were also scoped, and a preliminary estimate of aggregate size distribution made.

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Slope Stabilization Project

Weber Canyon, Utah

Amoco Pipeline Company

WSMC designed and constructed a stabilization system for slope failure that was endangering several pipelines. A geotechnical assessment of the slope was made to determine the mechanism of slope failure. An active resistance system using tensioned bolts and geogrid mat was designed to stabilize the area above the failure. This would act to protect the overlying pipeline right of way. WSMC acted as general contractor for construction of the stabilization system. Local subcontractors were used for labor on the project. Construction included drilling and bolting on a very steep slope, during winter conditions. The geogrid mat was laid and bolts tensioned, actively clamping the soil layer to the underlying bedrock. The surface was then seeded to US Forest Service specifications.

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Pond 4 Rehabilitation

Sweetwater County, Wyoming

General Chemical Corporation

David H. Scriven was construction manager for the rehabilitation of the Pond 4 embankments. The embankments were severely eroded from wave and wind action. The assignment included determining the physical characteristics of the fill material and measuring compaction of replaced fill. Construction management also included making major design changes for the upstream slope protection.

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Pond 5 Enlargement

Sweetwater County, Wyming

General Chemical Corporation

David H. Scriven was project manager for the design modification, permitting and construction for the enlargement of Pond 5. The design modifications included designing a chimney drain, realignment of the embankment, design of spillway and upstream slope projection. Permitting included State Engineer's Permit, and construction permits from the Wyoming Department of Environmental Quality, Water Quality Division. Construction management included all construction surveying, compaction testing, construction review, and development of as-built drawings.

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Tailings Cell D Modification

Sweetwater County, Wyoming

General Chemical Corporation

David H. Scriven was project manager and project engineer for modification of the Tailings Disposal Cell D Reservoir. The modification project included several phases of construction of a retrofit on an existing tailings disposal facility using upstream and downstream construction methods. The assignment included design, permitting and construction management for the project. Permitting included application for the State Engineer's Permit and Construction Permit from the Water Quality Division, Wyoming Department of Environmental Quality. The first phase of this project was completed in 1990, a second phase in 1992, a third phase in 1996. The fourth phase is scheduled for 2000 and the final phase for 2004. The designs include a rotating multi-point discharge to facilitate the use of sub-aerial deposition and the design of decant structures.

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Railroad Design Project

Eagle Butte Mine

Amax Coal West, Inc.

WSMC was in charge of the design of a Loop Track Extension and an Engine Storage Spur at the Eagle Butte Mine. The project included surveying the existing main line track into the plant site, design of 4800 feet of parallel track to the existing line, design of a 400 foot spur track for engine storage, development of construction specifications for both projects, preparation of all bid documents and the completion of an engineering cost estimate for each project.

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Mine Stability Evaluation

Sweetwater County, Wyoming

General Chemical Corporation

Scott P. Carlisle was the project engineer for the mine-wide stability evaluation of the Alchem Trona Mine. The evaluation considered mine layout, extraction, subsidence, rock strengths and in situ stresses. Numerical models of the mine were developed to estimate pillar stability. Areas were identified from this study for further investigation by field testing and instrumentation to quantify pillar conditions.

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Christensen Ranch Mine

Casper, Wyoming

Cogema Mining Company

WSMC was the geotechnical and structural foundation consultant in the design of a groundwater restoration facility for Cogema Mining Company, Christensen Ranch Mine. Working closely with Cogema process engineers a facility was designed to house the uranium recovery columns, reverse osmosis filters, pumps and piping to be used for cleanup of groundwater from the in-situ mine operations. The facility was located in difficult unstable soil conditions. WSMC was responsible for the geotechnical site investigation, piping layout and design of a deep foundation system. The foundation design used a deep pier foundation with slab and beam flooring to minimize the quantity of concrete required at the remote site location.

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Grouting Project

Spencer, South Dakota

Spencer Quarries Inc.

WSMC was asked to make an assessment of a substantial water inflow into a quartzite quarry operated by Spencer Quarries Inc. WSMC followed up the assessment with a design to grout off the inflow using chemical grouting techniques. The design called for drilling of a curtain wall and installation of sleeve port pipes for grout injection. WSMC also acted as general contractor for construction of the grout curtain. Denver Grouting and a local drilling contractor were used as subcontractors for this project. Grouting of the inflow was only partially effective. The grout curtain acted to contain the inflow but did not stop it. WSMC provided additional designs to excavate into the highwall along the inflow and construct an underground bulkhead too further contain and control the inflow.

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AML Projects 16-A, 16-D and 16-E-2; Gas Hills Uranium Reclamation

Cheyenne, Wyoming

Wyoming Department of Environmenta; Quality/Land Quality Division

David H. Scriven was the geotechnical consultant for the reclamation of the John Gunnel, Veca Pit, B Pits, and Tee Pits and a radiometric consultant for the reclamation of the B and Tee Pits. He was responsible for the subsurface geotechnical and radiometric investigations, the stability analyses of the highwalls and the surface radiometric survey of the spoil piles and surrounding areas. As part of the Design Investigation Report, he coordinated the geotechnical testing program and performed the analysis associated with the backfill operations of the reclamation plan and prepared radiometric isopach maps of the spoils and areas surrounding the pits showing various levels of radium 226 contamination.

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Riley Pass Reclamation Project

Hardin County, South Dakota

Custer National Forest

David H. Scriven was project manager for the investigation and design for the reclamation of the Riley Pass Uranium Mine, Hardin County, South Dakota. He managed a team of soil scientists, geomorphologists, biologists and health physicists to develop design alternatives for the project. The Riley Pass Mine was a surface mine, circa late 1950's, mining uranium associated with a thin coal seam overlying the rimrock. Spoil material was pushed over the rimrock creating an unstable and highly erosive surface. Several highwalls were left standing and ponded areas were created in the spoil piles. The project included the development of several reclamation alternatives. The alternatives were presented to the client to determine the one most suitable to their needs. Final design and bid documents were then prepared for the reclamation.

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Surface Drainage Design and Landslide Stabilization; Seneca No. 1 Mine Reclamation Project

Routt County, Colorado

Colorado Department of Natural Resources/Mined Land Reclamation Division

Several final pits in the Seneca No. 1 Surface Coal Mine were abandoned in the 1960's without being reclaimed. In addition, a progressive landslide aggravated by the abandoned mine land conditions threatened a county road, private property and a major stream course. The reclamation design included the routing of storm runoff through the reclaimed areas which were typically situated in steep terrain. The construction of numerous drop structures, rip rap lined channels, subsurface drains and compacted dikes was required. Approximately 200,000 cubic yards of earthwork was involved in the project. David H. Scriven was staff engineer for the field investigations, analysis and designs for stabilization of the landslide and the reclamation of the mined-out areas and also help prepare the construction bid documentation (drawings and specifications) and assisted the State of Colorado in the pre-bid conferences and bid evaluation (the project was divided into two construction contracts). Mr. Scriven was on the project's construction management team.

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Northside Mine Subsidence Study

Gallup, New Mexico

Alan K. Kuhn, Consultant and Abandoned Mine Land Bureau, State of New Mexico

David H. Scriven was the subsidence investigation specialist on the A.K. Kuhn team for the Northside Mine Subsidence Study in Gallup, New Mexico. His assignment included interviews/workshops with citizens; assistance to the State in locating subsurface investigation boreholes; assistance in structure investigations; drilling supervision and borehole logging; data analysis to define subsidence risk areas and subsidence mechanisms; evaluations of remedial actions.

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Glenrock Subsidence Control Project 8A

Converse County, Wyoming

Wyoming Department of Environmental Quality/Land Quality Division

The Town of Glenrock is underlain by two abandoned underground coal mines which are causing subsidence events on the surface. This project included a report of investigation to determine the most cost-effective approach to subsidence control, the design of a slurry backfill system to pump a sand/water mixture into the mine voids through boreholes, the generation of bid documentation and construction specifications and the construction management of the project for the State of Wyoming. The project also included design and construction management of an extensive grouting program for protection of structures and roadways in subsidence-prone areas where hydraulic backfilling would not be effective. The grouting applications follow:

• Development of grouted gravel columns, through boreholes, in the mains to contain the slurry backfill.
• Development of a cement-fly ash grout curtain around the perimeter of an apartment complex to contain weak backstow material in the underlying mine workings.
• Development and execution of a grouting program utilizing various drilling equipment and procedures and various grout mixtures to stabilize developed commercial and residential properties, streets and utilities that were threatened by subsidence.
• Stabilization of 1200 feet of State Highway 20-25 that was undermined and a very high subsidence risk.

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Superior AML Project 6B

Sweetwater County, Wyoming

Wyoming Department of Environmental Quality/Land Quality Division

The Town of Superior is located in a major turn-of-the-century coal mining district in southwestern Wyoming. Several hazards to the public associated with the abandoned underground coal mines had to be addressed. Our work included the following investigations, design, development of construction documents and construction management:

• Subsidence control by grouting beneath commercial structures and an undermined public school. A specialized grouting technique and grout mixture were used beneath the school because of the nature of the trough-type rock collapse and the weakened soils. The ground improvement involved the use of Tube-a-Manchette grout casing which allows for considerable control of the "zone" in which the grout is injected. The cement-fly ash grout base was designed for the special ground and injection conditions by incorporation of admixtures for strength (silica fume), fluidity and plasticity (polyethylene glycol), and set retardant (sugar).
• Closures for 32 abandoned coal mine openings (exposed adits and inclines, sink holes into mine workings).
• Reclamation of four coal waste areas.
• Closure of a concrete lined ventilation shaft.

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Geotechnical, Hydrological and Mining Engineering Support

Clear Creek/Central City Site RI/FS

Camp Dresser & McKee Inc. (CDM)

D.H. Scriven was staff engineer for the geotechnical subcontractor to CDM on the Remedial Investigation/Feasibility Study at five Superfund sites in Clear Creek and Gilpin Counties, Colorado. The sites included mine waste rock and tailings dumps, several adjacent to perennial streams. Mr. Scriven performed subsurface investigations (borehole drilling and sampling), piezometer installations, sample selection for physical testing, analysis of laboratory results and slope stability analysis. Stable configurations were determined and alternative remedial methods were evaluated. A comprehensive geotechnical report was prepared in support of and complementary to CDM's RI/FS efforts.

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Tailings Pond 4 Modification

Rhone-Poulenc of Wyoming Company; Big Island Mine

Jacobs Engineering Group

WSMC provided tailings dam design expertise to Jacobs Engineering for the Debottlenecking Project at the Rhone Poulenc of Wyoming Company Big Island Mine. We designed, permitted and provided construction review for the modification of Pond 4 to construct an interior tailings deposition area. The project included construction of two tailings cells each with decant tower and discharge pipe and embankments utilizing both upstream and downstream construction methods. The assignment included identification and testing of suitable borrow materials from within the already disturbed areas.

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Pond 1 Modification

Green River, Wyoming

Tenneco Soda Ash Company

WSMC provided design and permitting services for Tenneco Soda Ash Company to modify their evaporation pond and increase its storage capacity. The assignment included design of two auxiliary embankments with cementacious grout curtains for seepage control, a five to six foot downstream raise of the main embankment including installation of a chimney drain, and the design of two interceptor trenches and pumpback system. The modification constructed during the summer of 1992, added approximately 1300 acre feet of storage capacity to the facility. Project also included installation of eight monitor wells around the perimeter of the facility and five piezometer wells in the embankment.

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Laboratory Rock Mechanics Testing

Meeker, Colorado

Kennecott Colowyo Coal Company

Scott P. Carlisle was the project engineer on a rock mechanics laboratory investigation for a potential underground coal mine. Tests conducted were unconfined compressive strengths, triaxial strengths, brazil tensile strength, bulk density, porosity, and slake durability. Data from the seam, roof, and floor were collected and reduced to establish rock properties for mine development and longwall design.

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Rock Bolt Field Testing

Sweetwater County, Wyoming

Rhone-Poulenc-Big Island Mine

Scott P. Carlisle was the project engineer on a rock bolt evaluation program. The program evaluated different anchor horizons, and rock anchors with respect to the two beds in the mine. This work included rock bolt pull testing, torque testing, borescoping, and statistical analysis of the results. The results were given to the operator for consideration of changes in the rock support used at the mine.

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Field Instrmentation; Yucca Mountain Tunnel Project

Las Vegas, Nevada

N/A

Scott P. Carlisle was the project engineer for an extensive tunnel instrumentation project. This work included instrumentation selection and installation to achieve construction monitoring goals required by nuclear facility regulators. It also included selection and installation of data acquisition systems to facilitate instrument reading. Instrumentation included stress monitoring gages, convergence stations, borehole extensometers, rock bolt load cells, instrumented rock bolts, and steel set strain gages. Other aspects of the project included blast vibration monitoring for blast evaluation, and structural response to blasting and tunnel rock quality estimation for ground support selection.

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Subsidence Analysis

Hazard County, Kentucky

Whitaker Coal Company

Scott P. Carlisle was the senior engineer on a subsidence evaluation for a proposed underground coal mine. The mine was to be located under existing structures including residential buildings, power lines, gas wells and pipe lines. Estimates were made regarding stresses and displacements to these structures due to mine subsidence. Recommendations for protection of structures from subsidence were also included. This work was included as part of an overall mine feasibility project.

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Tunnel Design and Construction

Trementina, New Mexico

International Ground Support Systems

Scott P. Carlisle was the project engineer and construction superintendent for an underground records storage facility. This project included design and excavation of a shotcrete lined tunnel, installation of ventilation, lighting, and security, and design and construction of surface facilities. A preliminary design and site evaluation for a second facility using cut and cover tunnel techniques was also conducted for the client.

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Rock Mechanics

Lucky Friday and Star Mines

Hecla Mining Co.

Scott P. Carlisle was the rock mechanics engineer for these mines. Projects included rock support and opening design for high stress conditions, stope sequencing using numerical modeling, microseismic system design and installation, rock burst monitoring, and smooth wall blast design.

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Pond 3 North Embankment Dewatering Project

Green River, Wyoming

Texas-Gulf Soda Ash

Mike C. Hawks was the project hydrogeologist obtaining geologic and hydrologic data for the design of a dewatering/pumpback wellfield system for capture of seepage from Tailings Pond #3. The seepage was causing damage to local flora and creating areas of standing water near the toe of the dike impeding heavy equipment access for a proposed 8 ft lift on the dike. An extensive drilling and coring program coupled with aquifer pump tests was conducted to evaluate subsurface geologic conditions and aquifer properties. The dewatering/pumpback system dewatered the surface seeps allowing for pond expansion and increased soda ash production.

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Groundwater Restoration Facility Design; Coal Blending Conveyor Project

Glenrock, Wyoming

Glenrock Coal Company

WSMC was the design firm for the coal blending conveyor project for Glenrock Coal Company. The project included site layout and engineering for a feeder breaker, transfer conveyor and stockpile system to be used for blending pit run coal. A geotechnical investigation was conducted for the component sites. Designs were developed for the foundations of the feeder breaker and conveyor towers. Dump and stockpile retaining walls and a transfer tunnel escapeway were also included in the design package. Design drawings, technical specifications, and a bid package was prepared for purchase of the conveyor and for site construction and erection of the conveyor.