Subsurface Utility Engineering (SUE)
SUE provides a better method of acquiring subsurface utility information and eliminates the need to “find out the hard way” that plotted utility data was incorrect.
Benefits of using U.L.L.S., Inc.’s SUE services:
- Accurate and Verifiable Utility Information
- Reduced risk of utility strikes
- Improved site safety
- Reduced project delays due to unexpected conflicts
- Significant reduction in project costs due to costly utility relocations
The ability to obtain reliable underground utility information has
long been a troublesome problem for site owners, engineers and contractors. Subsurface Utility Engineering
(SUE) combines several technologies, including surface geophysics, vacuum excavation and utility mapping to
obtain reliable, accurate and up-to-date “quality level” information about the location, type, size, material
and condition of underground utilities.
Underground Utility Information Quality Levels
Quality levels may be thought of as degrees of risk, or how much information is really needed to adequately design and construct a project.
Quality level information may also be used to certify on project plans that a certain level of accuracy
and comprehensiveness has been provided.
There are four recognized quality levels of underground utility information ranging from Quality Level (QL) D (the lowest level) to Quality Level A (the highest level):
- QL-D is the most basic level of information for utility locations (i.e. existing utility records or verbal recollections, both typically unreliable sources). It may provide an overall “feel” for the congestion of utilities, but is often highly limited in terms of comprehensiveness and accuracy.
- QL-C is the most commonly used level of information. It involves surveying visible utility facilities (i.e. valve boxes, manholes, etc.) and correlating this information with existing utility records (QL-D information). When using this information, it is not unusual to find that many underground utilities have been omitted or erroneously plotted.
- QL-B involves the application of surface geophysical methods to determine the existence and horizontal position of virtually all utilities within the project limits. This activity is called “designating”. The information obtained in this manner is surveyed to provide project control. It addresses problems caused by inaccurate utility records, abandoned or unrecorded facilities and lost references. The proper selection and application of surface geophysical techniques for achieving QL-B data is critical.
- QL-A also known as “locating” is the highest level of accuracy presently available and involves the full use of the subsurface utility engineering services. It provides information for the precise plan and profile mapping of underground utilities through the nondestructive exposure of underground utilities, and also provides the type, size, condition, material and other characteristics of underground features.
The American Society of Civil Engineers (ASCE) recommendation for improving the level of utility locating and record keeping is to combine and use information from existing utility records, survey visible surface utility facilities, locate underground utilities using geophysical techniques, and pothole to verify and document the type, size, depth, condition and number of utilities present.