Subsurface Investigation Methodology


First and foremost, Subsurface Investigation Methodology, or SIM, is a process all successful subsurface inspection companies must follow in order to create a safe, secure job site. The SIM method entails a set of steps to prevent accidental and unwanted damages when drilling or digging underground. The SIM Specification standard is the industry-leading, metrics-based guideline for the underground locating and concrete scanning industries. More importantly, the SIM method contains three main elements that make it the go to process for industry professionals.



The SIM standard specifies that a professional locating contractor must utilize multiple locating technologies. In the field, GPRS alternates between ground penetrating radar (GPR) and electromagnetic pipe locators (EM). By using multiple technologies during the locating process, it allows Project Managers to capitalize on each tool’s strength, creating a redundant confirmation when designating and investigating subsurface elements.



All GPRS Project Managers are required to complete a minimum of 8 weeks of field mentoring, overlooked by an expert GPRS field staff member, in addition to 2 weeks of classroom training to become prepared for their mentorship. GPRS’ extensive SIM-standard training helps our Project Managers feel confident in their role and perform their duties to the highest standards for our clients.



Training and technology are only as good as the process that follows. SIM addresses a step-by-step approach to collecting subsurface data to ensure that the results are repeatable and accurate. SIM-qualified practitioners must follow a checklist that is designed to ensure optimal results for every situation encountered in the field.

The combination of all three elements permits Project Managers and field personnel to ensure safety on all construction project sites. The SIM method then helps subsurface contractors to establish a well-constructed ground disturbance plan for their clients. Furthermore, the implementation and creation of the SIM Standard is backed by proven accuracy. In 2019, there was a reported 99.8% accuracy rate out of 70,000+ projects completed, further proving that the elements of SIM are proven to help project sites avoid costly delays and unwanted injuries during the pre and post construction phases.

A safe ground disturbance plan includes the following:

  1. Information about sub-surface hazards should be gained by examining existing records, drawings, or oral collections.
  2. Obtaining information about utility or reinforcement whereabouts by visually examining above ground features.
  3. Hiring a locating/scanner contractor that follows a strict specification for training, equipment, and methodology.
  4. Determine precise horizontal and vertical location of utilities and reinforcement prior to excavation, coring, or drilling.