Geotechnical Engineering

For 50 years, TTL has provided geotechnical engineering services to a consistently growing clientele that includes:

  • Institutional
  • Industrial
  • Commercial
  • State DOT’s
  • City, County, State & Federal Agencies
  • Healthcare providers

TTL’s geotechnical professionals have years of extensive experience in diverse and challenging geotechnical projects, and bring competence, experience and innovation to projects, always seeking to add value and be your consultant of choice.

We assist our clients in implementing cost effective quality assurance programs for construction and developing cost-saving approaches to challenges posed by site conditions and geotechnical restraints.

Seismic Consulting Services

The International Building Code (IBC) that has been adopted by most local governing bodies requires the structural designer to assign a site class (A through F) to every building project. The seismic site class depends on the soil and rock conditions within 100 feet below the site. The site class is most often evaluated using data from soil borings, but the IBC places conservative limits on site class when using boring data. That conservatism can have a significant impact on the structural & mechanical systems used during building construction. The IBC allows evaluation of seismic site class on the basis of the measured or estimated shear wave velocity profile below the site and that method is not subject to the same conservative limits applied to boring data. Measuring the shear wave velocity profile at the site can sometimes improve the seismic site class compared to what boring data may indicate, which can result in a more economical structural & mechanical design and allow an owner to realize a substantial saving in construction costs.

TTL uses a geophysical method (Refraction Microtremor, or ReMi) that does not require drilling or sampling to quickly and cost-effectively measure the shear wave velocity profile below a site.

Often the desire to improve the seismic site class is related to the Seismic Design Category (SDC) that is assigned to every project based on seismic parameters calculated using the seismic site class. It may not always be possible to improve the seismic site class, but it may still be possible to improve the SDC by performing a site-specific seismic analysis (SSSA). The SSSA consists of modeling the ground motions produced at a site by local and distant earthquake sources using knowledge of regional geologic and site-specific soil and rock conditions. TTL performs SSSAs according to requirements of the IBC and ASCE 7 using the programs EZ‑FRISK and SHAKE91. Our extensive experience with these analyses allows us to quickly produce results which most often allow the maximum reduction in seismic parameters and frequently justify an improved SDC. We welcome the opportunity to discuss how our seismic consulting capabilities can assist you with reducing the costs of design and construction of your next project.

Drilling Services

TTL provides our clients with high-quality assistance in obtaining reliable subsurface data. We maintain our own in-house fleet of truck-mounted and all-terrain drilling rigs. TTL’s drill crews are experienced in hollow-stem auger drilling, rotary drilling, and wire-line core drilling. We specialize in the construction and installation of piezometers, monitoring wells, multi-cased wells and large-diameter recovery wells. Our drilling personnel are trained in accordance with 29CFR 1910.120 and are qualified to drill in Level D, C, and B personal protective equipment.