About Subsurface Investigation Methodology
The mission of Subsurface Investigation Methodology or (SIM) is to raise the quality of subsurface investigation results in the industry through creation of two specifications, one underground utility and one concrete. These specifications combine the requirements of experienced based training, tested technologies and proven application methods. The combination results in an industry standard for nondestructive investigation of underground utilities and scanning concrete. SIM as a standard will ensure safety, limit damage to underground and structural assets as well as increase location contractor accountability on site.
The need for SIM:
The construction and environmental industries make up the largest user market for the need to nondestructively locate subsurface targets like underground utilities and critical targets in concrete. Typical operations performed in these industries include trenching, soil boring and core drilling or saw cutting of concrete. Without location of the unknown utilities and other subsurface critical targets safety hazards and damages to property is likely to occur.
SIM represents the first comprehensive specification that quantifies the need for highly trained professionals as well as multiple technologies combined with proven field methods to produce the best nondestructive results.
Currently these industries at a minimum utilize a, “Call Before You Dig”, service contracted by local utilities to use as-built drawings and standard pipe location equipment to mark out known underground utilities. This is a free service that has limitations in technology and private property access. The service has been successful in raising awareness and greatly enhancing site safety but is not a full solution.
Additional to the call before you dig contractor these industries can utilize a private contractor that can overcome the shortfalls of the one call free service. Currently there is not a national certification required for utility location companies. There are training programs, best practices and specifications for operating specific technologies but nothing comprehensive in nature.
The SIM specifications allow the general contractor and environmental consultant a system of compliance to get the best results. There are three important pieces to compliance with SIM:
1. Investment in training technicians with an aptitude for puzzle solving. The American Society of Nondestructive testing recommends in “Practice SNT-TC-1A, Personnel Qualification and Certification in Nondestructive Testing Level I “, 8 hours as a minimum for training and a minimum of 60 hours practicing Ground Penetrating RADAR in order to be a certified NDT Level I in Ground Penetrating Radar (GPR).
SIM requires 4 weeks of field mentoring prior to 80 hours of classroom training followed up by an additional 4 weeks of field mentoring prior to release into the field.
2. The investment into multiple technologies as solutions in the field. SIM specification details two primary technologies for investigation. The first being a standard pipe locator but used to it full capabilities not just in a passive mode. The second, Ground Penetrating RADAR (GPR). GPR is briefly explained in the SIM specification supporting white paper. In short, the locating strategy is to incorporate both technologies in the same area thus capitalizing on the possible redundant confirmation of the depth and location of a target. This can be applied to underground utilities or scanning concrete to locate steel reinforcement or conduits imbedded in the concrete slab.
3. The third compliance metric is the applied methods on site. Each technology needs to be utilized systematically to collect subsurface data. This data is then compared with information specific to the site collected in a pre-scan interview with site contacts. SIM practitioners are required to follow a checklist designed to overcome weakness in each technology and achieve the best results for the site conditions.
The need for SIM is to provide clients with the ability to hold location contractors accountable to the three metrics of, required experience based training, multiple location technologies, and applied methods to enhance results as well as overcome weaknesses in the equipment.