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West Coast Drilling is a General Engineering Contractor specializing in CIDH Concrete Piles, Drilled Concrete Soldier Piles, Tiebacks. Micro-Piles, Soil Nails, Design Build Shoring and Design Build Earth Retaining Structures. WCD is a union contractor, a certified DBE, WMBE and SBE, and we have been in business since 1975 performing public and private drilling work for foundations and earth retaining structures.
Micropiles/Tiedown Anchors are deep foundation elements constructed using high strength, small diameter steel casing and/or threaded bars. Micropiles can be installed with larger drilling equipment, or they can be installed with smaller equipment that can pass through doorways and operate in headroom of 10’, making micropiles ideally suited to structural upgrades, seismic retrofit and underpinning of existing structures.
Soil Nails are fully threaded steel bars, placed into pre-drilled holes and grouted to keep them in place. Soil nails are placed horizontally into the soil and provide support to a soil mass by transferring tensile loads throughout the ground area. Soil Nails are place in a close grid pattern of 5’ – 6’ horizontally and vertically. The face of the wall is usually done in 6’ staged lifts and mira drain, wire mesh reinforcement and shotcrete are applied during each 6’ lift. Soil nails can be installed with larger drilling equipment, or they can be installed with smaller equipment in tight spaces where access and noise control may be an issue.
Ground Anchor / Tieback
A tieback is a structural, sub horizontal element installed in soil or rock to transfer applied tensile load into the ground. Typically in the form of a bar or strand, a tieback is commonly used along with other retaining systems (e.g. soldier piles, sheet piles, secant and tangent walls) to provide additional stability to cantilevered retaining walls. With one end of the tieback secured to the wall, the other end is anchored to a stable structure, such as a concrete deadman which has been driven into the ground or anchored into earth with sufficient resistance. The tieback-deadman structure resists forces that would otherwise cause the wall to lean, as for example, when a seawall is pushed seaward by water trapped on the landward side after a heavy rain.
Tiebacks are drilled into soil using a small diameter shaft, and usually installed at an angle of 15 to 45 degrees. They can be either drilled directly into a soldier pile, or through a wale installed between consecutive piles. Grouted tiebacks can be constructed as steel rods drilled through a concrete wall out into the soil or bedrock on the other side. Grout is then pumped under pressure into the tieback anchor holes to increase soil resistance and thereby prevent tiebacks from pulling out, reducing the risk for wall destabilization.
Secant Pile Wall
Secant pile walls are constructed by drilling in a series of alternating primary (drilled first) and secondary (drilled second) overlapping shafts to perform a continuing secant wall. Secant pile walls are used when sensitive structures are located behind the wall and when controlling the flow of groundwater is necessary. Tiebacks are drilled into soil using a small diameter shaft, and usually installed at an angle of 15 to 45 degrees. They can be either drilled directly into a soldier pile, or through a wale installed between consecutive piles. Grouted tiebacks can be constructed as steel rods drilled through a concrete wall out into the soil or bedrock on the other side. Grout is then pumped under pressure into the tieback anchor holes to increase soil resistance and thereby prevent tiebacks from pulling out, reducing the risk for wall destabilization.
Drilled Shafts – CIDH Piles
Drilled shafts are machine drilled piles that were developed for the transfer of high loads and as an alternative to driven piles. West Coast Drilling has an extensive fleet of drill rigs such as limited access, long reach, portable, low overhead, and large diameter piers. Our variety of equipment allows us to successfully complete diverse projects safely and expediently.
Helical piles are wound into the ground much like a screw into wood and are installed using a wide variety of earth moving equipment fitted with rotary hydraulic attachments. Helical piles are advantageous due to lack of spoils, vibrations, and dewatering and are used in tight access or low overhead situations.
Soldier Piles are wide flange steel beams set in drilled shafts space at 6’ – 8’ on center, filled with concrete and or lean concrete. Wood lagging, precast concrete lagging, CIP concrete or shotcrete is place in between the flanges of the soldier piles to act as soil support. They are typically used for retaining walls and are suitable for many retaining wall applications.
Design Build Excavation Shoring
Design build shoring systems would be designed by WCD and would utilize soldier piles, secant piles, tiebacks with wood lagging or soil nails and shotcrete depending on the soil conditions and site access. These shoring systems can be priced based on a preliminary design put together by WCD, so the General Contractor can include the excavation shoring costs in their proposal to the owner. Engineered stamped shoring designs would be provided after award of the contract.