Subsurface Utility Engineering (SUE) is a specialty practice of Civil Engineering’s Utility Engineering branch that includes the investigation, analysis, judgment, and documentation of existing utility networks. SUE focuses on underground networks but can also include aspects of above-ground networks. Lawrence Arcand, from 4Sight, was on the committee developing the new updates to the ASCE 38 Standard and therefore has a solid knowledge of how to use it effectively.
Traditional project deliverables typically include a SUE report and CAD drawing. 3D models that adhere to the quality level requirements are now becoming more common place. 4Sight has the ability to handle all sizes of SUE investigations.
Quality Level Definitions direct from ASCE - UESI Standard 38 proposed updates.
Quality Level A (QLA): A value assigned to that portion (x, y, and z geometry) of a Utility Segment or subsurface Utility Feature that is directly exposed and measured, and whose location and dimensions are tied to the Project Survey Datum. Other measurable, observable, and judged Utility Attributes are also recorded. If obtained by means of a Test Hole observation, a verification effort is made and professional judgment used to assert that the exposed infrastructure is indeed the sought target. The Utility Segment or subsurface Utility Feature shall be tied to the Project Survey Datum with an accuracy of 0.1 feet (30-mm) vertical and to 0.2 feet (60-mm) horizontal for the measurements of the outside limits of the Utility Feature or Utility Segment that is exposed. The assignment of QLA conveys the lowest level of relative (non-quantifiable) uncertainty of measurable and judged Attributes, and location. QLA is more certain than QLB, QLC or QLD.
Quality Level B (QLB): A value assigned to a Utility Segment or subsurface Utility Feature whose existence and horizontal position is based upon Geophysical Methods combined with professional judgment and whose location is tied to the Project Survey Datum. A QLB value is assigned to a Utility Segment when the following conditions are met: (a) the Utility Segment was detected through the application of appropriate Geophysical Methods; and (b) the geophysical signal was judged to be reliable; (c) the interpreted position was judged based upon knowledge and use of geophysical science, Utility design and installation practices, available records, visual features, and influence of site conditions; and (d) the source Designation has been tied to the Project Survey Datum with an accuracy of 0.2 feet horizontally. QLB is more uncertain than QLA and more certain than QLC or QLD.
Quality Level C (QLC): A value assigned to a Utility Segment not visible at the ground surface whose estimated position is judged through correlating Utility records or similar evidence to Utility Features, visible above and/or below ground. The Utility Anchor Point on the Utility Features shall be tied to the Project Survey Datum with an accuracy of 0.2 feet (60-mm) horizontal. A QLC value judgment is assigned to a Utility Segment by using visible Utility Features to approximate the position of a Utility Segment between or in proximity to the visible Utility Features and in context with other achieved Utility Quality Levels. QLC only pertains to the underground Utility Segment(s), not the Utility Feature(s). QLC data is more uncertain than QLB and QLA.
Quality Level D (QLD): A value assigned to a Utility Segment or Utility Feature, not visible at the ground surface, whose estimated position is judged through Utility records, information from others, or from visual clues such as pavement cuts, obvious trenches, or existence of service. A QLD data Attribute is assigned to a Utility Segment or Utility Feature after review and compilation of existing records, oral recollections, One-Call or “private-locate” markings, managed data repositories, context with other achieved Utility Quality Levels, and/or other evidence of existence. QLD data is more uncertain than QLC, QLB, and QLA. QLD data is less uncertain than utilities documented without any Utility Quality Level barring a Professional’s statement of fact to the contrary.
Following SUE processes is the best way to produce a comprehensive, reliable map of your underground and aerial utilities on your project, however, it is not the only way. If you are interested in taking on some of the investigation process and responsibility yourself, 4Sight will work with you to cost effectively get you the information needed to manage your Utility Risks.