Ground Improvement and Stabilization

Lateral earth support (LES) is often required with subsurface site development to:

• Provide safe retention of otherwise unstable soils during deep excavations
• Protect or isolate sensitive adjacent structures, or
• Allow downward excavation without encroachment onto adjacent properties.

GeoInsight staff members have consulted on and designed numerous complex LES systems, many in congested urban locations. Our design experience includes numerous temporary and permanent retention techniques, such as:

• Gravity walls (rock, cast-in-place concrete, cribbing, and precast concrete)
• Mechanically-stabilized earth walls
• Soldier beams and lagging
• Sheet piling, and
• Soil nailing.

Often, existing structures require additional support because of actual or potential foundation movement due to excessive settlements or proposed excavation. GeoInsight is familiar with numerous techniques to shore up existing features with piles, cast-in-place concrete underpinnings, and grout. We can identify economical solutions to address proper support of existing foundations and slabs damaged by settlement or movement. We can design underpinning systems and sequences to transfer foundation support to a deeper layer, thereby allowing vertical excavation to occur directly adjacent to an existing foundation.

Projects with cuts into existing natural or constructed slopes usually require slope stability analysis. These assessments may be focused on large-scale slope failures, smaller failures within the slope itself, or sliding of the slope layers. GeoInsight has performed numerous slope stability evaluations associated with:

• Existing dams, embankments, and natural slopes
• Earth removal operation designs to promote a safe sequence of cuts or stable final topography
• Planning of new versus existing grades
• The effects of water (natural seepage versus water introduced by septic systems, for example)
• The introduction of new structures on slopes such as landfill caps, foundation loads, and retaining walls, and

• Seismic forces.

We provide recommendations and designs for slope stability monitoring and improvement, including:

• Slope face treatment (i.e., rip rap) or conturing
• Surface water control (i.e., diversion swales)
• Ground water control (i.e., interceptor trenches or finger drains)
• Hydrostatic pressure relief (i.e., wick drains)
• Deep-slope reinforcement (i.e., soil nailing), and
• Toe-of-slope buttressing.

GeoInsight personnel have recommended and designed numerous weak-ground improvement programs including:

• Foundation surcharge design and monitoring (i.e. preloading)
• Pressure grouting; dynamic compaction of soils
• Feep vibratory compaction, and
• Soil displacement piles. 

We can help you evaluate your densification objectives, and the costs involved, increasing your available options and making an unwelcome site attribute become viable for development.

Often, the most cost-effective solution for your site improvement needs involves overexcavation of existing unsuitable soil and replacement with structural soil, lightweight fills, or aggregate with special properties. We have applied this methodology to hundreds of sites and have a high degree of expertise supporting simple foundation systems. When possible, our assessments include the reuse of existing soils in compacted lifts (with or without mixing with other soils), creating a stable subgrade to support foundations while minimizing the need to import soils.

We test existing site soils as well as material from borrow pits or processors to identify the materials or material blends that will meet the soil support recommendations. We also provide field oversight of installation to ensure that compaction requirements are met.

Geosynthetics are a popular construction material as owners, regulators, and designers gain familiarity with the capabilities, cost savings, and sustainability aspects associated with their use. GeoInsight evaluates, recommends, designs, and installs many types of geosynthetics, including:

• Woven and non-woven fabrics typically used to separate, filter, reinforce, and drain soils
• Flexible membranes used to provide separation and liquid conveyance such as high density polyethylene, very low density polyethylene, chlorosulfonated polyethylene, and polyvinyl chloride
• Three-dimensional geonets to provide drainage channels and gas pathways
• High-strength geogrids for foundation base and slope tensile reinforcement
• Biodegradable mats for erosion control
• Three-dimensional geocells to confine materials for surface reinforcement
• Composite materials, such as bentonite clay-impregnated geotextiles, to provide liquid containment, and
• Synthetic fabrics and mats used to cushion adjacent surfaces or materials.

When water velocity and ground cover are incompatible, erosion can occur. This is especially common during construction, when soils are exposed and controls are needed to comply with storm water regulations. We design practical solutions that are economical, effective, and tailored to your site. Slope armor and erosion solutions include natural and synthetic erosion control blankets, vegetated slopes, rip rap armor, and sloping and mulching.

Erosion and Sediment Control Plans

Our Certified Professionals in Erosion and Sediment Control have prepared many different types of Erosion and Sediment Control Plans. We are familiar with the application, design, and construction of Best Management Practices used to control storm water. We keep abreast of innovative technologies employed for these purposes, and are familiar with performance data and manufacturer’s literature. Our experience and library of templates will result in significant cost and time savings for your project.