We stabilize infrastructure and enhance excavation safety with innovative earth retention systems.
Earth retention systems play a crucial role in protecting nearby infrastructure during excavation, preventing soil movement around critical infrastructure, and containing the movement of contaminated soil. These systems are essential for stabilizing slopes, supporting existing walls, creating highway bridge abutments and wing walls, building approach embankments, and supporting adjacent structures during excavation. They help stabilize lateral earth pressures, control movement, and drain potential groundwater, making them indispensable for both temporary excavations and permanent structures such as basement walls for large buildings.
Our comprehensive construction approach ensures that we effectively stabilize lateral earth pressures, control soil movement, and manage potential water pressure. We apply these systems across various applications to protect nearby foundations, enhance excavation safety, and mitigate slope instability.
At Forgen, we provide alternative delivery methods including early contractor involvement (ECI) in the project planning stages. By collaborating closely with clients from the outset, we can assess all relevant factors, provide expert guidance, and recommend the most suitable retention systems for specific site conditions. This proactive approach helps identify and mitigate potential challenges, streamline the decision-making process, and deliver tailored solutions that address project complexities effectively, ensuring a smooth and efficient path from concept to completion. For more information on the benefits of early involvement, please refer to our page on alternative delivery.
Earth Retention Capabilities
Sheet piles are driven or vibrated into the ground along a predetermined alignment, creating a continuous earth support wall. Cantilever walls are common, but sheet piles can also be laterally braced with tiebacks or internal supports to meet specific site needs. Manufactured from high-strength materials, these walls ensure excellent quality control and structural reliability.
At Forgen, we frequently implement sheet pile earth retention systems when the retained soil cannot be de-watered. We commonly use sheet pile walls for temporary excavation support, groundwater flow cutoffs, seawalls, cofferdams, and bulkheads. Cantilever walls typically require penetration depths of at least two times the height of the excavation. For example, for a 10-foot-high sheeted excavation, the sheet is driven at least 20 feet below the bottom. For excavation depths exceeding 10 to 15 feet or where wall surcharge loads are high, we incorporate tiebacks (anchors) or internal bracing to meet earth retention requirements.
Our expertise ensures the effective application of sheet pile walls for a variety of projects, delivering robust and reliable earth retention solutions.
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Soil-mixed retention walls are constructed by blending in-situ soil with cementitious binders to create a stable, impermeable barrier. This method is used for excavation support, groundwater cutoff, and slope stabilization. Soil-mixed retention walls provide excellent strength and durability, even in challenging soil conditions, while minimizing environmental impact. They are commonly employed in urban areas or confined spaces where conventional retaining methods may not be feasible.
Forgen uses soil mixing techniques to create earth-retaining structures that prevent groundwater flow. These structures stabilize loose soil, reducing the likelihood of settlement and structural damage.
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Tiebacks and anchors are tensioned steel tendons drilled and grouted into soil or rock to provide lateral support for retaining walls, basements, and bridge abutments. These systems stabilize excavation faces and transfer loads to deeper, more stable strata. They are highly adaptable to site constraints and offer long-term stability for retaining structures subjected to lateral forces.
Tiebacks, also referred to as anchors, are engineered tensile elements used for temporary or permanent lateral support in earth retention systems such as sheet pile walls, soldier pile and lagging walls, secant pile walls, and slurry walls. A typical tieback consists of a steel bar or tendon drilled and grouted into a predrilled hole, ensuring precision and efficiency in modern earth retention applications.
Secant pile walls are formed by overlapping reinforced concrete piles to create a continuous, watertight barrier for earth retention and groundwater control. These walls are widely used in deep excavations, tunnels, and basement construction due to their strength, stability, and adaptability to various soil and groundwater conditions. Their durability makes them a preferred choice for complex and high-risk projects.
Secant piles are particularly effective for excavations near critical infrastructure, such as adjoining buildings. Engineers utilize secant pile walls for multiple purposes, including temporary or permanent earth support, foundation support, and groundwater and seepage control.
Forgen reinforces every second shaft with a steel beam or reinforcing cage and fills intermediate shafts with lean concrete for most applications. For circular shaft excavations, vertical steel reinforcement is typically unnecessary, as the secant piles form a concrete compression ring.
Forgen employs secant piles for earth retention to provide structural stiffness, minimize settlement concerns, and offer alignment flexibility. The modular nature of secant pile wall installation allows for versatile layouts, accommodating complex geometries and project requirements.
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Soldier Pile and Lagging (SP&L) earth retention systems use closely spaced vertical steel piles with horizontal lagging installed between them. To install soldier piles, steel H-piles or drilling steel pipes are driven or vibrated into the ground before excavation. The piles are placed at close spacings, typically aSoldier pile walls consist of vertical steel H-piles driven into the ground, with timber, steel, or concrete lagging placed between them to retain soil. This system is commonly used for temporary excavation support in urban construction projects. Soldier pile walls are cost-effective, quick to install, and adaptable to varying site conditions. They provide reliable earth retention for shallow to moderate excavation depths while minimizing disturbance to adjacent structures
Soldier Pile and Lagging (SP&L) earth retention systems use closely spaced vertical steel piles with horizontal lagging installed between them. The piles, typically spaced about four to eight feet apart, are driven or vibrated into the ground before excavation begins. Excavation and lagging installation proceed in small vertical segments, usually about 2 to 4 feet at a time. Timber is the most common material for lagging, installed horizontally between the vertical piles as excavation deepens.
Once Forgen completes the pile installation, we begin the lagging installation and excavation work. The excavation proceeds in conjunction with the lagging installation in small segments, typically about 2 to 4 feet vertically. Forgen installs the lagging, usually made of timber, horizontally between the vertical piles. This segmental process continues as the total excavation depth increases.
Forgen often uses the SP&L system as a cantilever for shallow excavations. For deeper excavations or increased stability, we incorporate tiebacks or internal bracing. The SP&L systems offered by Forgen provide several advantages, including:
This modular and adaptable approach ensures effective earth retention solutions for a wide range of excavation projects.
Cofferdams are temporary, watertight enclosures used to retain soil and water, allowing construction activities to proceed in dry conditions. They are typically constructed using sheet piles, braced frameworks, or a combination of both. Cofferdams are essential for marine construction projects, including bridge piers, docks, and foundations in water bodies. They offer flexibility in design, rapid installation, and robust performance, ensuring safety and efficiency in challenging environments.
To create a dry work area, cofferdams are built by driving sheet piles into the bed to form a mostly watertight barrier. Water is pumped out to expose the bottom, enabling construction. To minimize groundwater seepage, Forgen drives piles to a depth specified by the design and engineering team. Pumps are used to manage any slow seepage that may occur during construction, maintaining dry and stable conditions throughout the project.
Project Experience
Alternative Delivery
We specialize in delivering projects through alternative contracting methods, aiming to improve quality, reduce costs, enhance efficiency, and manage risks. Our expertise in heavy civil, geotechnical construction, and environmental remediation allows us to provide innovative solutions with agility. Early stakeholder engagement ensures alignment of project goals, fostering transparency and accountability. By combining technical expertise with innovative problem-solving and strong client communication, we tailor our services to meet each project’s unique challenges, ensuring successful outcomes.
