Serving Maine, New Hampshire, Massachusetts, Connecticut, Rhode Island, & Vermont

Geotechnical Services

Understanding underground conditions and how your facility might be affected is important for project reliability, sustainability, and resiliency. Our collective staff experience includes construction of a wide variety of facilities from buildings, airports, bridges, tanks, pipelines, and landfills, to waterfront structures and marine facilities.

Our geotechnical services can help you identify opportunities and manage uncertainties and risks related to soil, groundwater, and bedrock. Uncertainties are often associated with construction costs such as bedrock excavation, unsuitable soil removal, and foundation type, and with service life performance such as maintenance and repair needs of buildings, roads, pipelines, machines, runways, and marine structures.

We'll help you build a project of higher quality, better value, and less risk.

Foundation and Site Evaluations

Geotechnical due diligence during the preconstruction phase increases your team's ability to influence final project costs, quality and schedule. For example, some parts of a site might be suitable for less expensive foundation types compared to other areas that may need a more expensive foundation or ground improvement . Understanding subsurface conditions early can help verify land development opportunities, and provide an opportunity to adjust design and budget before significant at-risk time and financial resources are committed. Examples of some areas we can help you with are:

  • Site feasibility
  • Spread, continuous, and mat foundations
  • Deep foundations including driven piles and drilled piers
  • Re-use of existing foundations
  • Onshore and sub-marine environments
  • Soil and rock exploration including borings and test pits
  • Borehole and well camera surveys
  • Geophysical seismic and subsurface obstruction surveys
  • Ground improvement techniques
  • Construction hazard correction
  • Settlement evaluations and remediation evaluations
  • Construction and post-construction performance monitoring
  • Field instrumentation including vibrating wire piezometers, settlement platforms, inclinometers, and seismographs
  • Soil resistivity testing for electrical grounding and corrosivity potential
  • Low Impact Development

Slope Stability/Landslides

Strength and safety of earthen slopes and embankments are issues common to site design in steep slope areas.

  • Coastal, marine, and riverbank shorelines
  • Earth and rock fill embankments
  • Natural and excavated rock slopes
  • Mechanically stabilized earth slopes and walls
  • Cast-in-place retaining walls
  • Short-term and service life stability
  • Landslide risk assessments

Pavement Design and Evaluation

Effectively designed and constructed pavements are safer, are easier to maintain and repair, are better for the environment, and leave a lasting impression about your community, facility and organization. Whether the pavement is for a local road or highway, runway or taxiway, or for a temporary construction road, reconstruction and repair can be costly and disruptive.

R.W. Gillespie & Associates can help design new pavements and develop strategies for pavement rehabilitation, taking into account variables such as:

  • Soil and groundwater conditions
  • Performance expectations and service life
  • Porous or non-porous pavement type
  • Bituminous or Portland concrete
  • Climate
  • Vehicle type and frequency
  • Local availability of construction materials
  • Local construction practice and methods

Construction Consultation

Issues related to geotechnical engineering, geology, geohydrology, or environmental science are often encountered during construction. Our construction consultation services (several are listed below) can help owners and contractors develop and evaluate alternative methods to achieve project design requirements in a timely and cost-effective manner.

  • Lightweight fill (geofoam, cellular concrete, crushed stone)
  • Specialty foundation construction such as soil and rock anchors, mini piles, underpinning, and tiebacks
  • Slurry trenches, and composite barrier liners and covers
  • Rock excavation
  • Pre-blast surveys and vibration monitoring
  • Dewatering and slope stability
  • Management of contaminated soils and groundwater
  • Pile capacity, wave equation, and load testing
  • Monitoring the effects of construction including settlement, lateral displacement, and groundwater impacts

Coastal Shoreline and Channel Protection

  • Geotechnical aspects of seawalls, bulkheads, and revetments
  • Wave height evaluations
  • Wave run-up and overtopping evaluations
  • Slope stabilization
  • Armor stone sizing
  • Channel erosion and stabilization evaluations
  • Culvert inlet and outlet protection

Resource Evaluations

Use of locally available soils and re-use of on-site materials are important to a project's sustainability, effect on the environment, and financial viability. We can help evaluate potential sources of sand, gravel, quarry rock, and clay liner soil. Tools we use to explore and evaluate potential sites include:

  • Site reconnaissance
  • Geologic mapping
  • Aerial photography
  • Test pits and borings
  • Material quality assessments
  • Groundwater level and flow evaluations
  • Laboratory testing including sieve analyses, California Bearing Ratio, LA Abrasion, Soundness

Forensic Assessments/Peer Review

  • Foundation types
  • Building crack damage and distortion
  • Building and pavement settlement
  • Pavement failure include rutting and crack damage
  • Sinkholes
  • Landslides and slope failures
  • Seismograph vibration monitoring and damage assessments
  • Pre-blast surveys
  • Earthwork construction
  • Hydraulics and hydrology

Dam Safety

  • Geotechnical investigations for design of dams and diversion structures
  • Dam failure investigations
  • Seepage and stability enhancement