With more than 14,000 miles of underground facilities, Detroit Edison cannot afford unnecessary dig-ins. The utility has taken steps to lessen the number of dig-ins associated with nicking or cutting an underground electric line. Detroit Edison (DECo; Detroit, Michigan, U.S.) employees have become active in the damage-prevention industry public education initiatives and field best practices to reduce utility damages.

On the national level, DECo represents the electric power industry by having members on the board of directors of the Common Ground Alliance. DECo also is active in shaping best practices for damage prevention, including a proposed National “3-Digit Number” initiative for call center notification.

DECo is heavily involved in Michigan’s “Raise the Flags and Dig Safely” educational program, informing residents of the potential dangers when digging into the ground as well as the preventative action required by the state of Michigan. Raise the Flags is the public awareness campaign of the Michigan Damage Prevention Board, a partnership of Michigan utilities and MISS DIG System Inc.

Statewide one-call systems are considered the cornerstone of damage prevention. DECo receives more than 400,000 facility-locating requests each year from MISS DIG Systems Inc., Michigan’s 24/7 one-call center.

Last year in Michigan, more than 10,000 incidents of damages to underground utilities were recorded. DECo and Michigan Consolidated Gas Co. (MichCon), DTE Energy’s gas subsidiary, along with MISS DIG Systems Inc., SBC, Association of Underground Contractors, Michigan’s Heavy Construction Association, the Michigan Public Service Commission and other utilities and telecommunication companies, formed the Michigan Damage Prevention Board to develop and implement best practices and educational programs with the goal of reducing dig-in accidents.

The Expense of Cable Cuts
In the power-delivery business, when an underground cable gets cut, our customers know it immediately. Line cuts also have a major impact on the power companies reputation, the lives of those involved in the dig-in may be endangered, and the cost to restoration and repair the facilities is significant.

When a cut occurs resulting in an outage, the customer calls our 800 hot-line number and reports the power interruption, which is entered into our graphical outage management system. The call is then “automatically” analyzed to reflect the service, and locates the transformer or primary protective device feeding the location of the interruption. Next, the closest or first-available splicing crew is dispatched to the outage location to assess the damage and make the necessary repairs. After the repair is complete, the crew processes a damage claim to recover the cost of the work. Last year, DECo processed in excess of 2000 underground damage claims, down from more than 3000 in 1999.

Prevention is Key
DECo believes the best way to handle underground cable damage is to prevent events before they occur. Linemen, who are stereotyped as climbing poles and operating out of buckets high in the air, are also fully trained on the four Dig Safety rules. Whether they are setting poles or installing cable, the four guidelines are taught and followed by all field personnel.

The Dig Safety Rules include:

• Call before you dig
• Wait the required amount of time
• Respect the marks
• Dig with care, which includes hand digging to expose utility lines.

Population Problems
MISS DIG customer representatives receive notifications of excavation at the call centers in Pontiac and Gladstone. If DECo’s facilities are affected by excavation, the utility is electronically notified via the call center Internet Web site of the proposed excavation and the start date. Michigan has a three-day waiting period with the exception of national holidays. This is the time allotted for locators to mark existing underground facilities. There are also provisions for emergency situations.

Finding and properly identifying other utilities in the metropolitan areas is one of DECo’s biggest challenges, especially when most utilities are buried in close proximity in a common right-of-way corridor which includes cable television and telephone cable. Water and sewer may also be in the right of way, but usually are buried much deeper because of Michigan’s cold winters. With the advent of competition in the telecom industry, many competitors vie for limited space in the rights-of-way to install fiber-optics and coaxial cable, creating a major concern for any utility wishing to rebuild, upgrade, or repair cable or pipe in these congested corridors.

Our company uses both outsourced contract locators, who are under multi-year agreements to locate gas and electric lines for us, and in-house locators from MichCon. Locators carry maps and drawings on laptop computers that have wireless connection for constant updates during field locating and marking of our electric and gas facilities.

Standard color-coding practices (blue – water, yellow – gas, red – electric and orange – other buried equipment) are used to mark the area where cable, pipelines and conduit are located. Underground facility owners, such as DECo, stake the approximate location of their equipment with flags and/or paint. The safe zone in Michigan is 60 inches and refers to the area in which excavators must stay outside when digging, boring or driving stakes, unless hand digging or using nonabrasive excavation equipment.

The Biggest Nightmare
All too often, underground cables are only slightly damaged and do not result in an immediate outage. The damage can range from slicing into the insulation, without cutting the cable or jacket, to merely placing a nick in the insulation, which is often the case with directional boring. The individual or crew may not know they caused damage, but invariably will backfill the location and leave the scene after completing their work. When this type of damage happens, it can be days, weeks, months or even years before an interruption occurs as a result of exposure to the elements and corrosion.

Nicks to cable that result in outages are the most expensive to repair because of the time needed to troubleshoot, then dig up the area and ultimately “try” to track down the individual or company responsible for the damage. Unlike a dig-up that results in an immediate interruption, a nick generally does not have an easily recognizable location of excavation. With these types of hits, it is hard to locate the actual failure point. Accordingly, splicers spend a great deal of time and effort to troubleshoot the suspected cable using a thumper on primary or a Dynatel on secondary, and then hand dig the damaged cable to make the repairs.

Recently, an excavator using directional boring hit a 120-kV high-pressure nitrogen transmission line. The failure occurred after the contractor left the site, but resulted in a significant outage to key facilities in downtown Detroit. The cost of repair of this instance was in excess of $100,000. Another series of events happened in a suburban community having telecommunication and cable television installations. Subcontractors provided directional boring installations. A few failures occurred during the installation, with significant failures occurring weeks, months and years following the work. Ultimately, the subcontractor could not be found.

No Warning, No Clues
When an unexplained failure occurs, the first thing workers must determine is if any excavation has been performed in the area. In some cases, a new fiber-optic cable was installed in the same right-of-way a year or more prior. When checking this possibility, look for a nicked cable that has been deteriorating since the damage occurred a year ago. To rub salt in the wound, there is often the added problem of tracking down the excavator, who, in many cases, was a subcontractor and is no longer working in the area with no way to reach for reimbursement.

Consequences
Damages to underground facilities have an adverse affect on customer reliability, endanger those who cause the damage and are extremely expensive to restore and repair. The best way to handle underground damage is to prevent it before it occurs. The best practices established through the Common Ground Alliance study of 1999 have had a significant impact on the decreasing number of underground damages. Since adopting the best practices in 2000, DECo’s damages have dropped an average of 8% each year. These numbers support the need for the combined efforts of facility owners, one-call centers, locators and excavators in getting the word out on best practices through advertising campaigns, such as Raise the Flags, trade journals, association support and working together cooperatively.

Alan J. Yonkman is director of Service Center Operations for Detroit Edison. He represents the electric power industry in the U.S. on the executive board of the Common Ground Alliance (www.commongroundalliance.com). yonkmana@dteenergy.com

The author would like to thank Robert Barrette, manager of power delivery and a member of Michigan’s Damage Prevention Council, for his contributions to this article. For more information about Dig Safely, visit www.digsafely.com.