The goal of any utility locate is to identify the buried service or services in a given area so that they can be protected during excavation or taken into account during the design phase of a civil engineering project.
The best possible outcome of that locate is no utility strikes during the dig and no surprises when construction is underway.
There are many factors which can influence the outcome of a given locate. You can control some, while others are environmental and you can do little to overcome them.
Despite a certain number of uncontrollable factors, many can be managed by the client or project Locator.
Here are five you as a client can do, based on my experience as a professional Locator, that will help you get the best locate outcome, reduce the risk of service strikes, and prevent you spending a dollar more than is necessary.
Tip # 1 - Plan Ahead
Never leave your underground service locate until the last minute. A quality utility locate requires preparation.
You should always aim to have the locate done well in advance of whatever project is underway.
If you have a 40-ton excavator arriving on site next Monday morning, don't call to arrange your cable locate at 3:00 pm on Friday.
Sure, there will always be emergencies that require a quick response, but they should be exceptions.
Utility location is a vital part of the excavation process and is not an "I almost forgot" task to be squeezed in at the last minute
It is never OK to start digging without having all the public utility records available. Most countries, or states, such as in the USA and Australia, have "one call" services. In New Zealand it's beforeUdig.
The one-call service puts each requestor in touch with the Utility's, like the power and gas companies, to have them send you a copy of the underground service records for your area of interest. They may also arrange locates by their internal staff if requested, but only for their assets.
By organising your cable locate in plenty of time, you immediately reduce the risk of a utility strike or damage to an underground service.
Underground asset information will not always be available before you're ready to start if you leave it too late. Some Utility's do not have automated response systems. For many, it is a totally or partially manual process.
Poor planning can mean excavation starts before all the information is back from the stakeholder asset owners, and the Locator arrives to find work has already got underway.
All professional Locators will be able to accommodate the occasional last-minute rush. If you make a habit of it, and you rely on the excellent service of your go-to Locator, they may eventually run out of patience.
Remember, "Proper preparation prevents poor performance" - James Baker.
Tip #2 - Be Clear on Scope
When engaging your professional Locator, be precise about the scope of work you have for them.
You need to be clear about the physical area that needs to be covered by the locate, what underground services you need to be found and marked, and what you expect as the final deliverable.
For most locates, the time it takes will have been estimated based on the scope of works received from the client.
Workload sizing helps with planning and allows the utility location business to arrange jobs based on mobilisation time, the time expected on site, and any post-field-work reporting.
If you book your Locator to check 100 square meters of a greenfield site, they will have some idea of the time it's likely to take. Arriving on site to have the area doubled to 200 square meters is going to make the job that much more significant.
If you asked to have a low voltage power cable located, but decide when your Locator gets there that they might as well do the phone cable and gas line, then that's going to add extra time to the job.
If you asked to have on-ground painted mark-up but then decide you need a survey-grade CAD drawing prepared, the job is going to take longer and be more complicated.
The risk in not precisely communicating your scope of work when you book the job, or well ahead of your Locator arriving on site, is that they will be unable to complete all your work on the day you need it.
With other jobs booked after yours, the Locator may need to leave the job incomplete and return when they have the next free slot.
If your locate is not unfinished, you may have to delay your excavation, or worse, if you choose to start digging anyway, have a higher risk of a utility strike.
All professional Locators will try to accommodate minor changes in scope, but won't thank you if it's significant and it disrupts the work plan they have established for the day or week.
Tip #3 - Be Patient
Locating underground services takes time, skill and effort.
Your professional Locator will follow a thorough process for the lowest risk possible of mislocated services or discovering unknown services during excavation.
One of the most often discussed problems amongst experienced Locators is having contractor crews standing around waiting to start digging while the locate is underway.
If you have followed tip # 1, then this shouldn't happen.
However, if the locate is last minute the Locator will likely arrive on site to find;
- the excavator operator sitting in his cab,
- contract staff waiting around in trucks,
- a project manager itching to get started, and
- several lorries parked up waiting to take away spoil.
This is not a good situation for any Locator to find themselves in. Your professional Locator will have a process and to do a quality job they have to follow it.
Having an entire construction crew watching their every move can be stressful even for hardened veterans.
In situations like this, be patient.
Let your Locator complete their process and try not to push them to get the job done quickly. A professional Locator will work efficiently, but they will resist being pressured into a quick once-over just so site works can get back on track.
A rushed job is a risky job. Follow tip number 1 or if you've missed out doing that, at least be patient and allow your Locator to finish.
Tip #4 - Declutter the Site
One of the most challenging sites for a Locator to deal with is a cluttered one.
Experienced and professional Locators will have dealt with all manner of sites, from an open paddock in the middle of nowhere to the restricted spaces found in sprawling industrial campuses.
Worksite clutter will negatively impact on the locate result you have requested.
If you've asked for your locate well ahead of actual excavation, the site may still be in active use. Stacks of pallets, shipping containers, rubbish, and parked up heavy machinery all make a locate more difficult.
Clutter can have a very negative effect on the work your Locator is doing.
It prevents easy access around the site and hinders scanning for buried services.
Large metallic objects in the area are also likely to distort the magnetic field radiating from a conductive source. Any distortion introduces error in the horizontal position and depths of detected services.
Clutter may also obscure ground-level infrastructure features that your Locator uses as visual clues on services in the work area.
Using Ground Penetrating Radar (GPR) in cluttered or restricted space is also challenging.
The type of smaller GPR unit favoured by professional Locators scans a single line of ground about half a meter wide. This requires several passes over the area of interest in at least two directions and if being done to a high standard, in the two diagonal directions as well.
GPR works best when passing over an underground feature at 90 degrees. At other angles, the feature is often less evident. Being able to scan through a full area with as few above-ground obstacles as possible will give the best result.
On behalf of all professional Locators everywhere, I'm going to ask you to get your locate done before temporary work site fencing gets erected. If there is one structure that gives more problems than any other, it is temporary construction fencing.
Often erected just on or just outside the property boundary it usually sits over at least a few underground services in the footpath or berm. Long runs of temporary fencing can have a substantial negative impact on the accuracy of conductive services being located.
Using GPR also becomes a problem because the fencing prevents crossing over anything directly underneath it. A professional Locator may well open up panels in the fence to get around this issue, but this takes time and imposes limits on how much of the area can they can scan.
Tip # 5 - Get a Debrief
When your Locator has finished, you need to get a debrief from them.
The debrief may take different forms depending on what you asked your Locator to provide as the final deliverable. This goes back to tip number 2, being clear on the scope of works.
At the very least, your Locator should speak to you after the fieldwork has finished.
Many jobs have a few curly situations, and these need to be communicated to the client and then passed on to the staff doing the excavation. These cases might include;
- unknown services that can't be attributed to an identifiable asset owner,
- known services that could not be positively located,
- the presence of high hazard services in the area such as 11,000 volt buried cables,
- places within the work area that might have a high level of uncertainty, or
- unusual or strange features identified with the GPR. Many a long-forgotten buried underground storage tank (UST) has been found while locating services in older areas.
If you have requested something more complex like a survey-grade as-laid CAD plan or GIS input file, then it is likely you will get a full report provided by the locating company or the lead Locator.
Irrespective of the scope of works you set initially, having followed tip number 2, you should still get a debrief from the Locator when they have finished.
If you don't get a call or speak to your Locator while they were on site, make sure you follow it up before site excavation gets underway.
Innes Fisher is the founder and Managing Director of Utility Location Services New Zealand. He is a professional certified Locator active in the field and the New Zealand damage prevention community. Past President of Nulca New Zealand, international speaker and author.