In my view the main issues are what does best practice mean and to who? When do you apply Best Practice? Who takes responsibility for the process and the information? Who pays the bill?
You can then add to the Best Practice thought process – who is at risk? Who is responsible for them? How do we best control and minimise risk? Who pays the bill?
As background to my following comments, I have listened to a number of presentations on this topic at offshore conferences to find similar views expressed from clients, consultants and contractors. At one conference in the USA I had lunch with a “÷One Call Deputy’ whose role was to inspect road works and ensure all service location paperwork was in place.
I have monitored developments in:
“¢ Locating and mapping systems development for many years, first looking at equipment like ground probing radar and three dimensional mapping systems in 1995 in the UK;
“¢ The application of bore planning software which can also be used for trench planning;
“¢ Equipment such as vacuum excavation and its applications since 1999; and
“¢ SUE (subsurface utility engineering) documentation and some of the systems developed by the Common Ground Alliance and Witten Technologies who specialise in underground investigation and mapping.
In 2000 I was involved with the establishment of a company to locate and verify trench routes at the time of design, as part of the planning process, rather than at the time of construction. I have also been involved in discussions with service authorities and other agencies who are involved in the underground industry.
How do we protect our business and staff from harm?
Don’t dig a hole!
While this may be the answer, it isn’t a solution because without digging the hole we don’t have a business and people don’t have access to utility services that they have come to expect.
We collectively have to eliminate or minimise the risk to our staff. This can be achieved if we collectively get it right and appropriate people or organisations take their responsibilities seriously and meet their true commitments to get their project built.
From a health and safety perspective, everyone involved in the project has a responsibility for the safety of the employees and others on the worksite. While the employer carries the bulk of the responsibility, the client and the consultant are not excluded from these responsibilities; they have to get it right as well.
This “÷all in’ responsibility concept appears to be foreign to many consultants and clients. Based on my experience to date the consultant and client view would appear to be that existing services are just something that the contractor can deal with as he finds them. Of course this couldn’t be further from the truth, but while this attitude prevails, unnecessary 3rd party damage will continue to occur.
Inaccurate service information is another issue that not only leads to service damage but is a major contributor to additional costs in the form of rework and site delays, amongst other things. How much time does the contractor spend looking for a service which is shown on a plan or marked in the field? It is in these situations that service verification is required because in many instances inaccurate information has a significant potential to cause harm to the workers on the site.
To support these comments, we see many excavation contracts that treat existing services as a non-issue – “÷services are the responsibility of the contractor’. We then get a plan with a green line on it and are asked for a price. If the contractor is smart he will price the green line subject to service clearance but in many cases the consultant is expecting the contractor to verify the trench route as part of the pricing process. They are expecting the contractor to provide an unpaid consulting service, otherwise the contractor simply takes the risk. The consultant wants to be paid for investigation and design services, why shouldn’t the contractor? The consultant gets time to do the necessary leg work and appropriate investigation, if the consultant isn’t going to do what is required but expects the contractor to do it, why shouldn’t the contractor be given sufficient time and an appropriate payment for doing what needs to be done?
If the contractor prices the green line, wins the job, obtains a service mark out and then starts digging he will usually find another service on the same alignment. We have started projects on this basis which have resulted in the new service eventually being relocated to the other side of the road because no one did their homework properly in the first place and there was no space for the green line at their preferred position. The cost is time, saw cutting, some excavation, investigation on the other side of the road, new street opening notice, new TMP, and a lot of frustration.
In our worst case we drilled into a 33 kV cable which wasn’t there, luckily we missed the 200 mm gas main which also wasn’t there according to the plans supplied at the time of the walkover with the client and the property owner.
Best practice starts at route design and it has to include site verification of the service plans that are supplied at the time.
As-built records
Good accurate as-built records that include service depth will minimise investigation costs, construction costs and hazards on site.
While some clients have good accurate as-built information, most don’t, and we have found this is especially so for large private companies on industrial sites such as meat works and dairy companies and other sites such as schools and universities. Many utility owners and business owners need to take more responsibility in this area because they are not keeping as-built records that are suitable for new excavation work, let alone provide sufficient information to make the most of the benefits offered by newer technology.
A case in point is the application of directional drilling and installing pipe without excavation. While as-built service plans indicate position, very few indicate depth and more specifically changes in depth.
If we are drilling and have to cross a service, unless we know how deep it is we will dig it up and check it. I have discussed this aspect with various local authorities, utility companies and Transit NZ but I don’t know if they have looked at changing their as built information requirements.
While we are seeing trenchless solutions being specified more often, the quality of the base information supplied in many cases does not allow the trenchless operator to provide the maximum benefit from the technology.
Best practice
Best practice costs, and at the end of the day the client has to be prepared to pay the bill to get it. From my experience, while the client wants best practice and is prepared to specify it, especially for construction he generally does not appear to be prepared to pay for it, either at the time of design or during construction. If best practice was required, service location companies should be run off their feet, but again from our experience this isn’t the case.
We have invested in top of the line electro magnetic tracking equipment via our Pathfinders Services Company but we only service our own operations because there is no demand from other contractors or clients.
We have continued to monitor GPR, 3 dimensional mapping and vacuum excavation but to date we have not been able to locate clients who are prepared to pay for these extra services so we have not been prepared to invest in them. Our clients know that we will invest in new technology if they want the technology and the levels of service that the technologies can provide but to date there has been no demand.
Best practice also has to consider the people who are involved in this industry and their skill and knowledge levels. The person in the trench with the shovel and the guy on the
digger are not there because they have a degree in rocket science and they may struggle with written instructions and plan reading (not that they will admit it in most cases).
Our company has a hand dig policy within 500 mm either side of a marked service but we have broken services with a shovel in hard ground while looking for them. We have had brain fade from operators who have broken services after they have been exposed. In a recent incident a staff member cut a power cable with a hand saw while cutting into a newly laid PVC duct immediately above it.
While we can minimise the damage with good best practice, including investigation, design, field operations and specialist equipment, damage will still happen because that is the nature of the people we have in the industry and that is the bottom line, next to who will pay the bill. Best practice will not happen on lowest price for the work. It can happen for those who are prepared to pay but they will probably need to change the way they employ their contractors (including designers) by considering pre-registration, partnering and a documented location procedure.
A staged level of quality for service location is very important if costs are to be kept in perspective. Understanding the limitation of the location equipment is very important, for example my understanding of GPR would suggest that there are more limitations than those outlined such as water table depth, certain types of soil conditions, multiple service trenches and the actual survey methodology used.
Service protection is of particular interest to our company and something that gets discussed often by our directors. We have two crews (and sometimes more) digging up city streets full time and we have service strikes. While we appear to have a few (because we are working in this environment all the time) a recent analysis of our strike history over the last three years indicates that we actually damage less than 1 per cent of the services that we cross with an excavation and half of those are not known. We believe this is a very good result and put it down to the systems and procedures we have in place, our version of best practice. However, we can always do better but this would require additional investment in equipment, staff and procedures. From our perspective of the current market there is no opportunity to get a return on that investment, in fact the additional costs would simply price us out of that market altogether.
Recent incidents
A gas service was marked by the gas department with a 1 m envelope but the service was actually 900 mm outside that envelope – as a result, the pipe was broken.
A power service was marked on site by the land owner using a cable locator and because it was on private property the local supply authority had no record of the cables on the site. The actual cable was found 9 m from its marked position and from my knowledge of tracking equipment, it isn’t possible to be that far away, but when our staff could not find the cable in the first instance they asked for a remark and the same position was confirmed. We hit the cable and a staff member received an electric shock which required medical treatment. We checked the site using our equipment and while we found cable where we hit it we could not detect any kind of signal 9 m away where it had been marked incorrectly.
Power service plans supplied for an 11 kV cable featured a hand written warning on the plan stating that there is some doubt about the position of the cable shown on the plan.
A service plan supplied with confusing information – the plan was supplied as a gas service plan and our staff read the bold dimensions as the gas pipe location. Because they were digging to 3.2 m deep, they did not pot hole the services in advance as this creates an unsafe situation in the trench as we get close to the pothole. The gas pipe was broken nearly 3 m away from where we were expecting it to be from interpretation of the supplied plan. We ended up with a major drama on site, with police and the fire brigade called out and house evacuations required. We have since had a long ongoing discussion with the utility owner over who was at fault. The gas dimensions were on the plan but in light grey. The bold dimensions on the plan referred to a power cable, not the gas main as read by our staff. While the dimensions for the cable were shown on the plan the actual dotted cable was left off the plan. This was due to the wrong layers being switched off on the CAD system, a simple error which could be costly.
At the end of the day the contractor is responsible for the safety of his staff, so how much faith can the contractor place in information supplied to him? If he has to do everything from scratch this will increase costs and who pays the bill?
Conclusions
What is industry best practice for dealing with underground services? Underground services have to be dealt with at the time of design. They are not the contractor’s problem at the time of pricing or worse still, construction.
Best practice involves:
“¢ Service plans
“¢ Verification of the information
– electronic location
– sonde location of open pipe networks
– ground probing radar on closed pipe networks.
– pot holing if required (vacuum excavation)
“¢ Site sweep for the unknown service (Multi array ground probing radar)
“¢ 3D mapping of the site to accurately position the services
“¢ Good design based on the above results
“¢ Then to pricing or tender
The contractor has the ultimate responsibility for his staff, the client has the ultimate responsibility to notify the contractor of any hazards on their work site. So why not do it properly? Doing so should reduce the price for the work because it will reduce the risk to the contractor and his staff and it will remove the client’s liability for safety, costly rework and production delays. A win-win for both parties – but the consultant has to put it in place.
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