Geotechnical Drilling Projects, Drilling Contractor Holt Services, Inc., Seattle / Edgewood, WA

With a diverse fleet of drilling equipment and drillers with extensive geotechnical drilling experience, we enable organizations to gather vital construction-related data. Here's a sampling of recently completed geotechnical drilling projects.

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CHEHALIS DAM, PHASE II, PE ELL, WA
Geotechnical drilling to obtain data related to design and construction of a potential dam in Western WA.

Nineteen borings were drilled to depths of up to 350 feet using the direct mud rotary drilling method.

PQ and HQ3 coring was performed in selected zones. Split spoon samples were collected every five feet in the overburden materials. Packer testing was performed in 10 foot over-lapped intervals using an HQ wire line, packer assembly. The drilling crew assisted with suspension and tele-viewer logging.

Eight 2.75 inch inclinometers with vibrating wire piezometers (VWP) were installed in addition to 11 VWPs without inclinometers.

Surface completions were 12-inch flush monuments.

Formations consisted of weathered zones of basalt, fractured basalt, with interbeds of siltstone.

Challenging site conditions included: site access, drilling through landslide debris, surface cobbles, and wood debris.

Client: State of Washington
Drill Rig: Mobile B-54 track mounted
Drilling Method: Mud Rotary
Duration: 3 months
Completed: April 2015

GEOTECHNICAL DRILLING, HISTORIC COWLITZ RIVER BRIDGE CROSSING, CASTLE ROCK, WA
Perform geotechnical drilling to facilitate the design of both railroad bridge replacement abutments.

Two 6 inch mud rotary boreholes were drilled to a depth of 150 feet. Split spoon samples taken at 5 foot intervals in over burden materials to a depth of 83 feet. Drilling continued using HQ3 coring tools with diamond core bits to core competent rock to 150 feet.

All drilling was done in environmentally sensitive areas adjacent to waterways and wetlands requiring best management practices to minimize intrusions.

Access to the existing historic bridge abutments was made possible via a crane lift from the main-line tracks down to each drill location.

Client: BNSF Railroad
Drill Rig: Mobile B-54 track mounted rig
Drilling Method: Mud Rotary
Duration: 1 week
Completed: April 2015

KACHESS DROUGHT RELIEF PUMPING PLANT, KACHESS RESERVOIR, WA
Identify and sample along the proposed Kachess Inactive Storage Alternatives.

Identify and sample overburden and bedrock materials along the proposed Kachess Inactive Storage Alternatives to better characterize subsurface conditions.

Sonic drilling and sampling methods of the overburden material provided high production rates and quality/quantity of samples for testing. Retrieval of HQ3 cored bedrock was used for classification and determination of material strengths.

Land borings up to 330 feet
Overwater borings up to 200 feet below mud line in up to 150 feet of water, from anchored barge

Collect, bag, and box continuous sonic core to bedrock, then HQ3 diamond core to total depth. Collect SPT drive samples at select intervals in overburden for classification and gradation determination. Perform continuous packer testing in bedrock. Assist with downhole suspension and tele-viewer logging. Construct 2-inch PVC monitor wells.

Client: Bureau of Reclamation, Yakima Basin Integrated Plan
Drill Rig: TSi 150CC limited access, rubber track mounted rig
Drilling Method: Sonic
Duration: 2013 - 2014
Completed: 2014

SOUND TRANSIT EAST LINK TUNNEL ALIGNMENT GEOTECHNICAL STUDY, BELLEVUE, WA
Investigative drilling to confirm an anomaly discovered in a construction excavation.

Perform investigative drilling to confirm an anomaly discovered in a large construction excavation near the tunnel alignment for a new section of Sound Transit's East Link transportation corridor.

Two of the three boreholes drilled made contact with the formation of concern and the data obtained helped to mitigate potential impacts due to the tunneling operations in the immediate area.

Holt Services, Inc.'s TSi 150CC Compact Crawler rubber track mounted sonic drill rig met the challenges of conducting drilling operations with a small footprint on a paved area in busy urban environment. The sonic drilling method also provided quality formation samples at a 45-degree angle and the ability to install three vibrating wire piezometers (VWP).

Client: Golder Associates
Drill Rig: TSi Sonic 150CC limited access, rubber track mounted rig
Drilling Method: Sonic Drilling
Duration: 2 weeks
Completed: October 2013

SOUND TRANSIT EAST LINK, CONTRACT E-330, DOWNTOWN BELLEVUE, WA
Install inclinometers in tunneling vicinity to detect unstable conditions resulting from tunneling operations.

Install 20 inclinometers up to 90 feet, 9 multi-point-borehole-extensometers (MPBX) up to 50 feet and 5 observation wells up to 85 feet.

The inclinometers are placed near the outside limits of the tunnel sides while the MPBX's are placed near the crown of the tunnel. The scientific instrumentation provides data for quality control purposes to determine if unstable conditions are resulting from the tunneling operations.

Challenging conditions included: drilling in an urban area on city streets, sidewalks with pedestrians, and busy city traffic. All drilling locations were potentially riddled with utilities that needed positive locating. The surface was cored and an air knife vacuum truck was used at every location prior to drilling to safely locate underground utilities.

Client: Geo Instruments
Drill Rig: Mobile B-59
Drilling Method: Mud Rotary
Duration: 3 months
Completed: October 2016