Benefits of Using Subsurface Utility Engineering for HDD Projects
June 30, 2017Historically, the word “utilities” was considered a four letter word to many engineers, designers and contractors simply because conflicts with buried utilities accounted for the majority of the cost and scheduling over-runs on construction projects.
Robert L. Clemens Jr. wrote this article, which originally appeared in the 2011 Trenchless Technology HDD Guide. As we are celebrating our 25th anniversary, we’re going back and posting a variety of articles from past issues .
Over the years, this stigma has slowly changed for the better with advancements in technology and the further development of subsurface utility engineering (SUE) and horizontal directional drilling (HDD) processes.
The use of subsurface utility engineering during HDD projects — whether it is during design or the actual construction — has become a normal operating procedure or a requirement for many departments of transportation (DOTs), municipalities and utility owners. This is due to the fact that subsurface utility engineering accurately maps the horizontal and vertical location of underground utilities providing the necessary data to avoid damage to underground facilities.
The marriage of HDD and subsurface utility engineering allows a driller to maneuver around existing underground utilities or avoid them all together. This significantly minimizes the risk of a utility strike and, often, eliminating unnecessary utility relocations. Breaking ground can be risky business; knowing what’s underneath the surface and where it is helps to minimize this risk.
Subsurface utility engineering has evolved from a test hole (ASCE Quality Level A) focus to a stronger designating (ASCE Quality Level B) focus and work efforts have gone from 99 percent in the design phase of a project to a three to one ratio of design and construction. This swing is in part due to the cost associated with right of way acquisition and owners doing more within a limited space. This change has lead to more drilling within rights of way by utility owners. The ability to do less with more is also due to the development of a more sophisticated drilling method — HDD. Instead of drilling straight down or at a linear angle, advanced technology allows drill operators to maneuver the head through a maze of utility facilities.
In many states, contacting the one-call system is a required step prior to construction or breaking ground. This valued system has its place providing the “approximate” horizontal location of utilities prior to construction. However, drilling and avoiding the approximate horizontal location of a utility can be hazardous to the driller, the public and any buried facility in the corridor. Because of this, most if not all, HDD installers field verify the utilities to the best of their ability prior to drilling. When subsurface utility engineering is used prior to construction the need for field verification goes away as both the horizontal and vertical component of a buried utility is provided to the contractor or engineer by the subsurface utility engineering provider. When projects used subsurface utility engineering early in the design or construction process, the project plans depict highly accurate utility locations that provide a road map for horizontal directional drilling.
The requirement for completing ASCE Quality Level A subsurface utility engineering prior to starting a horizontal directional drill has almost become mandatory to reduce risk in many areas around the country. The contractor completing the HDD is financially responsible for any damage to other facilities (drainage, utilities and other equipment) during the drill operation. If during the HDD, a contractor damages a facility, it could actually cause additional damage to other facilities and compromise the structural integrity of a road, highway or vertical structure. This utility damage has the potential to cause voids or fissures and damage to roadways increasing repair costs, all of which becomes the financial responsibility of the contractor or their insurance carrier. Frequent claims to a contractor’s insurance causes an increase in premiums, which makes ASCE Quality Level A subsurface utility engineering (at a minimum) prior to starting a HDD an apparent necessity.
In some states when subsurface utility engineering is not completed or required during the design phase, SUE providers are often called in during construction. This is especially evident on compensable interest projects where the state or owner is paying utility costs. Instead of paying downtime to the contractor, while utility companies decide where they are and why they are in conflict, subsurface utility engineering can be completed to minimize the delays. The same holds true for the HDD effort, if a contractor damages a major utility system then construction operations could be interrupted resulting in work delays/non-budgeted financial costs for the owner.
In today’s economy more than ever, there is an increased need to ensure that damage to buried facilities that result in financial hardship to a contractor, the public, utility owners or engineer is held to a minimum. The benefits of completing subsurface utility engineering during the design or construction of a HDD project has proved time and time again to far outweigh the cost. These savings of time, money and effort are evident in the projects listed below.
An example of a subsurface utility engineering provider’s ability to quickly mobilize resources for a HDD installation in construction is the Ohio DOT West Avenue Emergency Project (PID No. 23062). Cardno TBE provided approximately 500 lf of designating (ASCE Quality Level B) and three test holes (ASCE Quality Level A) on the existing Level 3 Communication’s fiber-optic line within the project limits. This project was already under construction when Cardno TBE began its subsurface utility engineering work. The project contractor needed to know the location of the existing fiber-optic line so a directional sewer bore could be completed. Coordinating with Level 3 Communication, Cardno TBE field crews successfully located the fiber-optic line. A 12-in. diameter, 15-ft PVC pipe was placed in the test hole so the contractor was able to physically see the fiber-optic line during directional boring operations. Because of Cardno TBE’s quick response to this emergency project, the contractor’s downtime was minimal prior to completing the installation.
The utility owners have also used these services. The Ameritech Phone Co. was in its relocation operations in Bloomington for an Indiana DOT project when Cardno TBE was called upon to provide approximately 2,500 lf of designating (ASCE Quality Level B) and eight test holes (ASCE Quality Level A). Cardno TBE placed 12-in. diameter, 8-ft long cardboard cylinders in the test holes so the HDD contractor was able to see the buried phone and fiber-optic lines during construction. With months in between Cardno TBE’s services and highway construction, this helped maintain the integrity of the utility as opposed to traditional PVC piping used on projects where there is a shorter timeframe.
Applied early in the design or construction phase, subsurface utility engineering minimizes risk and saves time and money for all parties involved with HDD projects. The recognized benefits include: time savings for the HDD installer, a true clear window available for drilling operations, minimized damage to utility facilities and the owner’s ability to continue minimizing his or her right of way acquisition needs. Subsurface utility engineering can also reduce project impacts to construction schedules, the traveling public and business owners within the construction zone.
Robert L. Clemens Jr. is a vice president of Cardno TBE with more than 30 years of experience. He has managed/directed the successful completion of more than 1,400 subsurface utility engineering and utility coordination projects of various size and scope in nearly 25 states.