Q & A with Robert Edwards and Mark Bruce
At the CGA 811 Excavation Safety Conference & Expo held in Phoenix this past March, a panel of industry leaders came together to explore the concerns of the water and sewer industry and address the most important topics of the day. Moderated by Dr. Samuel Ariaratnam (Arizona State University), the panel included Mark Bruce (Cross Bore Safety Association), Robert Edwards (Citizens Energy Group), Joseph Murphy (North Wales Water), and Monty Zimmerman (City of Lenexa).
Damage Prevention Professional recently talked with two of these experts, Robert Edwards and Mark Bruce, about their contributions to the summit. They shared their responses to several topics under discussion.
ARE WATER OR SEWER SYSTEMS MORE VULNERABLE AND WHY?
Robert Edwards: Within the Citizens Energy Group Water System based in Indianapolis, Indiana there is approximately 4,700 miles of water main. The pipe material of the water system changes constantly in Marion County and the surrounding eight counties Citizens Energy Group serves. Each material type and the method of installation can be very vulnerable to damage from digging excavations, horizontal directional boring and vertical soil boring. All the pipe materials found in Citizens Energy Group’s water system is cast iron with lead poured joints, cast iron with mechanical joints, reinforced concrete, ductile iron, PVC and polyethylene. Each of these pipes need to be treated with care to avoid damage. Water mains are pressurized with 60-100 psi and maintain that pressure with the use of pumping systems. If a water main is damaged, water will flow until main line valves are closed. A water system controlled by a Central Control Station must be notified before closing valves to prevent potentially more damage. Earlier pipe installation dating from 1871 to the twentieth century had either lead poured joints or mechanical joints with bends, tees and hydrants held in place with thrust blocks or concrete kickers. If a contractor digs, trenches or bores near these concrete kickers the integrity of the support system is jeopardized and bends are separated, tees kick out and hydrants blow off causing serious flooding. Just before the end of the twentieth century, restraints for all fittings and pipe joints were developed. Each year, pipe installation technology continues to improve and accidental damages steadily decrease.
Hydrants are not the only asset connected to a water main that is vulnerable to damage. Small service lines (¾-inch to 2-inch) are often a target for damage. Copper service line connected to a PVC main increases the odds that the main will split. Other assets connected to a water main, including blow off assemblies, sample stations, air reliefs, pump outs, pito taps and post indicators, may not always be understood by everyone working near them. It is very important for contractors to understand the operation of these assets and how to work safely near them.
BEST PRACTICES TO HELP PROTECT A WATER MAIN SYSTEM
The number one best practice for contractors to implement is daylighting any utility in conflict with a project. Once the utility is spotted by hand digging or vacuum excavation, mechanical equipment may not be used within two feet of the utility. Once the utility is totally exposed, a spotter can direct mechanical equipment within the two-foot zone. Before choosing a route for new installation of pipes, conduits or cables, always check with utility operators close to the chosen route and agree upon the separation required. Some common mistakes made in the field while determining the elevation of water mains stem from contractors trying to avoid daylighting. Some water mains have several valves connected to the system, and it may seem like an easy checkpoint for elevation knowledge. The fact is, the average person does not know the make of the valve or size. Is it a gate valve, butterfly valve, hydra stop valve, hydrant branch valve installed with a grad-lock, lay down valve or bypass valve? All these valves have varying elevations which are different from the top elevation of the water main.
Lastly, on the topic of valves, while looking into a valve box riser are you checking the elevation of the valve key nut or is this a valve key extension? There are hundreds of valve key extensions within the Citizens Energy Group Water System and they are of all different lengths.
Another common mistake involves trace wire. How was it installed? Where was it installed? Trace wire is installed to help the operator of the water main system locate the pipes and service lines throughout the life of the system. The operator of the water system grants permission to their selected locate company to also use the trace wire. The operator of the water system and the locate company know how and where the trace wire is installed. Many contractors today own a pipe locator and assume they understand how all water systems are installed. The fact is, the trace wire may be installed above or below the pipe, on one side or the other, with the pipe or by itself. Once the signal is homed in on, the pipe locator’s receiver may indicate a depth on the screen. This depth is for the trace wire, NOT the water main or service line. In Indiana, the Dig Law protects utility locate companies on the side-to-side locate marks with a 24-inch buffer on each side of the marks.
Any contractor working near a water main system needs to have a general knowledge of the system. If there are any conflicts, please contact the operator of the system as quickly as possible! After all, we all share the same rights-of-way and easements, so let’s work together to prevent utility damages.
Mark Bruce: Water and sewer systems have always been vulnerable. Typically, sewer mains are lower elevation while shallower sewer laterals are more likely to be damaged by other utility installations such as communication, natural gas distribution and water. Aging infrastructure improvements, including water loss regulations, reduction of sewer inflows to reduce overflows, and requirements for safety and methane release reduction for natural gas distribution are increasing the opportunities for installation damages. Mandates for natural gas distribution system replacement is estimated at more than $300 billion dollars over the next 15 to 20 years. Past and future cross bores from trenchless gas distribution line installations are estimated to result in over 250,000 cross bores of sewers, with more than 80% of those being sewer laterals.
IS THERE CURRENTLY AN ISSUE REQUIRING PROTECTION OF WATER AND SEWER INFRASTRUCTURE? IS THIS REALLY A PROBLEM?
Robert Edwards: The right-of-way is full! After a period of time, the rights-of-way not located in a street are used up by several utilities. Certain utilities like separation or spacing between their utility and others. Many utility companies and internet service providers choose to use directional drilling to install new pipes and cables or replace old pipes or cables. When you compare the cost of restoration, equipment needed, labor, environmental impact and safety between directional drilling and open cutting a trench, directional drilling is the best choice – if it is done right!
After 811 is contacted and the project site is located, a bore route is determined by the directional bore crew. If the portion of the right-of-way not in the street is filled by other utilities, the crew will typically bore over the water or sewer marks as those utilities are typically installed deeper than three feet (especially in Indiana).
This creates a problem for utilities and conduits installed over water mains because all water mains will fail at some point due to their constant pressure, environmental changes underground and the temperature change of water in the pipe. When a water main has a failure due to a joint leak, crack, hole or split, an excavation large enough for a maintenance crew and their shoring system is required. It is very difficult to work with pipes, cables and conduits hanging over your head. Many water main failures damage other utility pipes, cables and conduits due to the pressure of the water leaving the pipe. When mixed with sand and gravel, a sand blasting effect develops that will cut PVC and poly.
Another problem with utilities placed too close to water mains is discovered when a new service line is needed for a customer. Again, an excavation with the proper shoring system is required before the main can be tapped. All water taps four inches and larger require up to six feet of additional room alongside the water main to accommodate a tapping machine.
Another concern with all water systems is the replacement of assets such as hydrants, valves, blow off assemblies, sample stations, air reliefs, meter pits and pump outs. To replace any of these assets (and they will have to be replaced at some time) an excavation with a shoring system installed is needed before the replacement can be completed. Utility pipes, cables and conduits installed around water system assets have forced water operators to take a lot more time to create a safe work site using expensive vacuum excavators and specialized shoring systems to complete an excavation. In some cases, assets must be moved to another location due to crowded underground utility conditions. As you might realize, there is a large amount of unnecessary expense involved.
The answer to overcrowded rights-of-way is to acquire an easement. That is what Citizens Energy Group does to install a water main. The cost of an easement would be less for each internet supplier if they combined resources and hired one contractor to install a conduit large enough to carry several different fiber cables or several different conduits within a single directional drill path. Just a thought!
Mark Bruce: The protection of water and sewer infrastructure remains an ongoing problem. Damage prevention efforts have been greatly successful, but frequent damage continues. Education and exposure to solutions are important drivers as technology allows more economical location of utilities to reduce damages. Attitudes for damage prevention are continuing to improve. Vacuum excavation is widely used to locate existing utilities, but it is expensive and, in itself, damaging to surfaces causing repair efforts. Evolutionary improvements result in better and higher accuracy solutions for continuing reductions in damages. For instance, with improvements to compact multiple antennae, multiple frequency ground penetrating radar has shown success, especially for shallow utilities. Looking ahead, HDD radar research is showing real promise in Europe.