GBI can prepare and deliver accurate mapping of existing underground utilities to assist project managers, engineers and designers during design phase and manage risk due to unexpected buried utilities during construction phase.
Subsurface Utility Engineering (SUE) is generally defined as the engineering analysis and process for determining the precise location of existing utilities within a given area and mapping the information obtained. The SUE process is composed of four (4) distinct Quality Levels:
Quality Level D (QL-D) is the most basic level of information for utility locations and is derived from record information, site conditions and verbal recollections from those familiar with a certain area. The data is compiled and mapped on a drawing with the QL-D designation. QL-D utility information is primarily used during the planning phase of projects and consists of the least accurate utility information.
Quality Level C (QL-C) involves the surveying of visible utility appurtenances (fire hydrants, valves, manholes, etc.). QL-C SUE produces a more accurate product because it takes surveyed data and correlates it with the QL-D record information.
Quality Level B (QL-B) involves designating the existing utilities (searching for the utilities using various types of electronic, sonic, acoustical, magnetic, radar, etc. equipment) and the processing and engineering analysis for determining if the information collected is correct) and marking the position of the utilities in the field. The field marks are then surveyed. This information is correlated with QL-D and QL-C data to produce a fairly accurate depiction of the location of underground utilities within a certain projects limits.
Quality Level A (QL-A) is the highest level of accuracy in the SUE process. QL-A involves the exposure of the utility, at specific points, through non-destructive excavation processes (vacuum/hydro/hand excavation). These exposures are called Test Holes. By exposing or “daylighting” a certain utility, accurate depths, size, material and condition can be observed and recorded. Test Hole Reports are prepared and the Test Hole locations are surveyed and plotted on the drawings.