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Our Expertise . . .

Overcoring Stress Determinations Since 1994

• Mining Engineering

• Ventilation Engineering

• Highwall Mining

• Blasting & Explosives Eng.

• Solution Mining

• Rock Mechanics

• Rock Testing

• Stress Measurements

• Forensic Engineering

• Geology & Drilling Management

Year

Client

Number of Successful Runs

2007

2

Acres International, Robert Moses Niagara Power Project

U.S. Bureau of Reclamation, Seminoe Dam

19

FMC, Westvaco Mine

12

OCI Wyoming, L.P., Big Island Mine

18

2002

OCI Wyoming, L.P., Big Island Mine

6

Dravo Lime Co., Black River Mine

15

Project Summaries - Mineral

2000

Mountain Coal Company, West Elk Mine

8

• Base Metals

• Coal

• Fertilizer Minerals

• Gold

• Limestone

• Oil Shale

• Trona

• Other

(click to view overcoring output)

OCI Wyoming, L.P., Big Island Mine

40

NIOSH, Tanoma Mine

2

CDC, Norton Energy Project

6

1999

CDC, Norton Energy Project

2

Stone & Webster Engineering, Santeetlah Dam (Fall '99)

15

Solvay Minerals

35

Stone & Webster Engineering, Santeetlah Dam (Winter '99)

15

1998

Stone & Webster Engineering, Santeetlah Dam (Fall '98)

67

OCI Wyoming, L.P., Big Island Mine

25

Energy West, Deer Creek Mine

5

Bowie Resources, Bowie #2 Mine

8

Stone & Webster Engineering, Santeetlah Dam (Spring '98)

68

1997

OCI Wyoming, L.P., Big Island Mine

14

Stone & Webster Engineering, Santeetlah Dam

20

Energy West, Deer Creek Mine

20

1996

Solvay Minerals

9

1995

Solvay Minerals

72

1994

Sandia National Laboratories, DNA

9

Project Summaries - Capability

Acres International, Robert Moses Niagara Power Project, Amherst, New York, USA
   Agapito Associates, Inc. was contracted to perform all aspects of an overcoring stress determination project designed by Acres International.  The object of the project was to determine the current stress condition in specific areas of the Robert Moses Niagara Power Project dam and power generation facility, and to provide a summary report.  The project included six holes drilled vertically down in the concrete, two holes drilled perpendicular to the downstream face of the dam and one hole vertically down in the rock beneath the concrete.  A total of 17 overcore runs were completed in concrete and 3 in rock.

   All drilling activities required recirculation and proper disposal of the drill water and drill cuttings.  Drilling was all done with AAI's CP-65 drill.  All drill water hauling and containment was accomplished with AAI equipment to meet operating and environmental constraints.  The project was completed without accidents or incidents within strict security procedures and strict environmental requirements.

Collecting overcore data at the Robert Moses Niagara Power Project (click to view larger photo)

• Backfill

• Block Caving

• Directional Drilling

• Forensics

• Geologic Studies

• Longwall

• Mine Reclamation

• Resource/Reserve Evaluation

• Slope Stability

• Solution Mining

• Subsidence

Preparing a biaxial test to establish rock modulus of elasticity (click to view larger photo)

FMC Corporation, Alkali Chemicals Division, Absolute Stress Determinations, Green River, Wyoming, USA
   Agapito Associates, Inc. was retained by FMC Corporation to determine absolute vertical stress levels at two locations previously instrumented with vibrating wire stress meters.  The USBM borehole deformation gage and overcoring method was to be used for the stress determination.  The measurements served two purposes:  (1) to quantify load transfer and (2) to establish a stress baseline in the pillars.  AAI provided all drilling equipment, two technicians, overcoring equipment, and specialized tools and supplies required for operation, calibration, and maintenance of the gages and equipment.

   Two horizontal holes 45 ft deep with six overcore runs each were completed.  The holes were drilled perpendicular from two 9-ft-high by 15-ft-wide entries mined with a bore miner.  The project was completed in 11 days with no accidents or incidents.  Mobilization into and demobilization out of the mine were expedited by the ability to hoist AAI's loaded trailer, saving several manual transfers of the equipment and supplies required to complete the project.

   A report of the details of the project and stress determination results was completed and submitted to FMC.
 

Stone & Webster Engineering, Santeetlah Dam, Robbinsville, North Carolina, USA
   The Santeetlah Dam, a concrete arch dam near Robbinsville, North Caroline, was constructed in 1928.  Ten years later, two large buttresses were constructed on the downstream side of the dam.  The owner was concerned that an alkaline-aggregate reaction might be occurring in the buttresses and that expansion of the buttresses caused by the reaction might be pushing the top of the concrete arch upstream.

   In order to determine if the dam was experiencing bending due to the expansion of the buttresses in 1981, stress determinations were conducted in the concrete arch.  Overcoring holes were drilled from the upstream side of the dam, just above the water level.  Three holes, at different angles, were drilled opposite each buttress and one overcoring hole was drilled in the center of the arch.  Stresses determined at these locations indicated that the dam was not experiencing significant bending stresses due to expansion of the buttresses.

   Subsequent work by AAI for Stone & Webster since 1997 included stress measurements in over 200 locations to establish the absolute stresses in the dam prior to installation of stress monitoring devices.  Slotting and tie-downs have been added to improve stability of the dam.
 

U.S. Bureau of Reclamation, Seminoe Dam, Wyoming, USA
   In August 2003, Agapito Associates, Inc. was contracted to supply the specialized equipment and personnel required to make overcore stress determinations at the USBR Seminoe Dam, located near Rawlins, Wyoming.  AAI provided the USBR with a summary report of the stress determinations and details of the overcoring activities.

   The project consisted of two vertical holes drilled from the crest of the dam and two horizontal holes drilled from the downstream face of the dam.  Eleven stress determinations were completed from 49 to 75 ft deep in the two vertical holes.  Nine stress determinations were completed in the two horizontal holes from 10 to 30 ft deep.

   All of the  drilling was done by the USBR Great Plains Regional Office personnel and equipment.  USBR drill rigs, a Sprague and Henwood 142-C and a Longyear LF-70, were set up on the two vertical holes and a Diamec 232, on the horizontal hole prior to AAI mobilizing to the site.  Each of the rigs had drilled to the depth of the first overcore run.  Upon arrival, the AAI technician worked with the USBR drillers to complete the stress determinations.  AAI supplied the USBM borehole deformation gages, gage cables, gage placement tools, strain indicators, calibration equipment, and specialized tools and supplies required for operation, calibration, and maintenance of the gages.

Overcoring with Diamec 232 core drill on downstream face of Seminoe Dam (click to view larger photo)

Drill rigs used for overcoring on crest of Seminoe Dam (click to view larger photo)