April 2018 Vol. 73 No. 4
Features
Modern Utility Investigations to Eliminate Some Project Risk
Editor’s Note: This is the final installment of an exclusive four-part series outlining the risks of modern underground utility infrastructure construction and rehabilitation work.
In Part 1, we introduced the concepts of underground uncertainties in infrastructure work. In Part 2, we looked specifically at how contract language allocates the resolution of risks of underground uncertainties of existing conditions (geotechnical data, utilities, and Constituents of Concern) between the engineer, contractor, and project owner. In part 3, we looked at how Geotechnical Baseline Reports are used to avoid disputes over differing site conditions and “base-lining” bids. This last article looks at how ASCE 38, Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data, serves as a template to perform adequate modern utility investigations that can be used to eliminate some amount of project risk during project development, and assist the design and utility engineer in managing the remaining risks.
The concept of a utility investigation ranges from doing virtually nothing; to investigating the current underground conditions; to using every conceivable method to try to find out the presence, location and condition of underground utilities. But the ends of the spectrum are not normal. With study after study showing that one of the top reasons for project delay claims is that utilities are not shown correctly on plans, we need to bring our technology and practices up to date to solve the problem. Many utility investigation techniques and methods are mired in practices that may have been relevant in the 1980s, but should have limited use in today’s world.
What are the last century’s practices? Mostly, they are reliance upon information from others that cannot be controlled as to quality and comprehensiveness, and excavation at select points to try to either confirm this information from others, or maybe get lucky and find something new. We see this procedure many times on design-build projects, where utility records and One-Call marks are used, along with many test holes, to accomplish the utility investigation. Utility records are notoriously inaccurate, incomplete, missing, never made, not available, difficult to interpret and not referenced to a recoverable datum. Test holes are destructive, expensive, time-consuming, disruptive to traffic and only give information at a spot location.
What is the solution? Basically, it is applying competent geophysical techniques as early in the project development process as possible. Geophysical techniques have had major improvements in hardware and software continuously since the 1970s and, yet, these techniques are rarely applied by the project owners and their engineers. When used to any extent, it’s generally by persons with little to no training in geophysics or the instrumentation. Most of the time, these services are applied by multiple parties, with no coordination between them to fully cover the project limits or ranges of conditions. I’m talking about One-Call services, developed and used for damage prevention for known utilities, and maybe GPR services performed by untrained people.
Advances
Advances in geophysical technologies for detecting utilities are taking place around the world. The European Union had its
ORFEUS (Optimizing Radar to Find Everything Under the Street) program. England had the Mapping the Underworld Project. And the United States had its Strategic Highway Research Program that developed multi-channel GPR and Time-Domain Electromagnetics specifically geared towards utility detection. Pipe and cable locating devices are some of the most sophisticated geophysical tools on the planet in recent years, and yet very few technicians know or are taught to use their full range of capabilities, or have a full range of frequencies and antennas available to them.
ASCE recognized the principles of a good utility investigation back in 1996 when it started its standards committee to develop ASCE 38. This standard has stood the test of time, but is still used only sporadically by project owners and engineers, mostly because of ignorance or a desire to gamble that utilities will not be an issue on their project. ASCE 38 basically says: a thorough utility investigation takes the results of a comprehensive, big-toolbox geophysical search for known and unknown utilities, and integrates them with existing records and physical evidence. Test holes are performed only where needed, virtually eliminating the issues of “dry” holes. It’s that simple.
All of the utility investigation takes place under the direct responsibility of a licensed professional engineer with training and working knowledge of surface geophysics, engineering surveying, utility construction and design principles, utility conflict identification and resolution, and utility risks as they pertain to the project. This professional is becoming defined as a utility engineer, and is one of the reasons for the genesis of ASCE’s Utility Engineering and Surveying Institute.
ASCE 38
Studies by Purdue, Penn State, University of Toronto and others consistently show a large return on investment for projects using ASCE 38. Knowledgeable contractors say they can provide better bid estimates when the results of utility investigations are displayed using ASCE 38 “Utility Quality Level” values. Use of ASCE 38 appears to be increasing rapidly as the industry shakes out the poor performers. In fact, Colorado has introduced legislation to make ASCE 38 mandatory for certain projects, just like a building code incorporates ASCE 7.
The competent use of ASCE 38 finds most of the utilities on a project, whether there are records or not. Applying a “Utility Quality Level” value attached to discrete utility segments allows users to understand the relative uncertainty of a utility’s depiction in its location and attributes. “QLA” means that utility was exposed at that exact spot and the uncertainty of its location is zero, although there is a risk that the utility may not be the one it was thought to be, so a small amount of uncertainty always exists. “QLB” means that geophysics was the method used to search for and find a particular utility segment. QLB is more uncertain due to errors in geophysics, interpretation and positioning. “QLC” is where only records and visible features are able to determine the best-judged position of a utility because the geophysics didn’t work, while “QLD” has no data other than records or One-Call marks, and are the most uncertain depiction.
Projects end up with a mixture of utility quality levels based on what was achieved and integrated during the geophysical, records and site-visible features investigation. This depiction of utility segments uses their judged relative uncertainty which allows the design engineer to make informed decisions on placement and type of design elements, and other project parameters.
The underground is uncertain when we can’t see it, and when accurate, comprehensive records are not available and guaranteed. We have come a long way in technology, contracts and case law, and practices to attempt to manage these uncertainties. There is continuous improvement, with the occasional back-sliding as technology claims by researchers and manufacturers don’t live up to new promises. Yet we so desperately want them to work that we try them in a project setting and discover the limitations. We have made progress since we started trying to tame uncertainty in the 1970s. There is more to go.
About the Author:
Jim Anspach is technical practice lead for Cardno Inc.’s Utility Engineering and Survey Practice. He serves as ASCE’s Utility Engineering and Surveying Institute President for 2018. He is the incoming chair for EJCDC, and chairs the ASCE 38 Standard Committee. He is also a member of ASCE’s Board Committee on Claims Reduction and Management.
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