An experienced underground-utility locator has dished the dirt on common mistakes people make when excavating, and given some tips on how to dig down safely.
Geelong Cable Locations Director Ben Minutoli has been protecting underground assets for 18 years, and is on the National Utility Locating Contractors Association committee.
Minutoli says damage to underground assets is still far too common. With excavators financially liable for damage, mistakes can have a costly, and sometimes dangerous, outcome – just ask the EnergyAustralia contractor who caused extensive damage to Telstra assets in the middle of Sydney in 2009. Thousands of homes and businesses in the CBD were without telephones and internet for at least one day.
Telstra made a video detailing the damage, which involved a trench digger hitting eight fibre optic cables, plus three major copper cables totalling 10,000 pairs of wire.
“Even though there’s a heap of locators out there, even though Dial Before You Dig (DBYD) is free, even though there’s a lot of education, there’s still far too much damage occurring,” Minutoli says.
DBYD is a national referral service designed to prevent damage and disruption to Australia’s vast pipe and cable networks. It passes requests for plans on to the affected asset owners, which then provide plans directly to the excavator.
Minutoli says, besides excavators being either too complacent or impatient, using insufficiently trained staff to read DBYD plans was a common recipe for disaster.
“It is a very common one among councils, road crews and other construction companies – the guys in the office sometimes don’t understand what it’s like out in the field,” he says.
“There are a lot of people who don’t understand the plans. It’s just down to experience and training. I could probably train someone how to read plans in half an hour – it’s not hard, but you do need someone to explain it.”
With locator technology now readily and cheaply available, Minutoli says many organisations are relying on inexperienced staff to locate underground assets.
“There’s a lot of council workers now who have gone through a basic locating course, and think that they can locate utilities. If a council employed a staff member to only do locating, and he went and did every locating job for them, they’ll probably be able to gain enough experience and would be fine.
“However, it’s far more common to have a different guy in every crew doing it. They buy a locator, but they don’t understand how to use it properly and they don’t understand the details of the plan.”
What to do when you dig
DBYD recommends the four Ps when excavating:
Plan: Plan your job. Use the DBYD service at least two business days before your job is due to begin to ensure you have the correct information you need to carry out a safe project.
Pothole: Potholing (hand digging) is a method to assist in establishing the exact location of all underground infrastructure.
Protect: Protecting and supporting the exposed infrastructure is the responsibility of the excavator. Always erect safety barriers in areas at risk to protect underground networks.
Proceed: Only when you have planned, potholed and put the protective measures in place.
Because not all underground asset owners are DBYD members, Minutoli says it pays to be aware of what may not be on the plans.
“In Melbourne, if you do a DBYD request, there will be stuff in the ground from Vic Roads that aren’t on the plans,” he says.
Plans to be used as a guide, not gospel
“What people don’t understand is DBYD is a relatively new thing,” Minutoli says. “A lot of these plans that have been drawn up are 40, 50 years old. The plans were drawn for the organisation. All the Telstra plans that were drawn up were drawn solely for Telstra’s internal use, as with Jemena, Melbourne Water etc. Some scale, some don’t, there’s no uniformity to the plans at all.
“And that’s the big issue with DBYD – a lot of people say to me, ‘The DBYD plans are wrong’. Some do have errors, but not often. Of all the plans I see, less than 10% have errors.
“You’ve just got to understand that they’re not to scale – they’re given as an assistance for you to locate assets. All the utilities want you to dig down by hand or use a hydro excavator to pothole and expose their assets. The plans are given as a guide.”
NBN fibre optic cables: A recipe for disaster?
The National Broadband Network (NBN) is being rolled out around Australia, with more than 1,390,000 premises ready for the service as of October 2015. Minutoli believes the plans lack sufficient detail and fears they will continue to create problems for excavators.
“The new plans coming out from NBN are absolutely disgraceful – they’re the worst I’ve ever seen,” Minutoli says. “There’s almost literally nothing on them, it’s a line on a map and that’s all. You can’t tell where you can hook on to it, you can’t tell if its laid by itself or with other cables, what size conduit it is in, there’s no details on it.”
Minutoli says he has encountered numerous issues relating to the plans, and has contacted NBN Co on a number of occasions.
“Everyone is aware of how bad they are. They are going to be a major problem,” he says.
An NBN Co spokesman says new information will be added to the plans, including detailing under-construction assets, to clearly identify all NBN owned assets.
“As NBN’s underground assets are primarily contained within Telstra ducting, our DBYD diagrams show only our own cable routes and not those owned by Telstra,” he says. “NBN recommends the usage of additional accredited locators to perform a further on-site search for any underground assets.”
“NBN is continually evaluating feedback from a wide range of industry partners to update and improve our DBYD plans and provide additional details,” he added.
“In terms of potholing, there’s a few different methods,” Minutoli says. “The traditional one that’s been around for years is hand-digging. Shovel only, no crowbars, and dig down until you see the utility.”
Minutoli recommends digging parallel to the utility, to minimise the risk of damage. “If the cable’s running north-south, you’re standing on the east or west side digging down, so that when you get to the utility, the shovel is more likely to rub around, over the top or underneath it, and the worse thing it will hopefully do is pick it up,” he adds.
“These days, non-destructive digging (NDD), or hydro-excavation or vacuum-excavation is the way we all do it. Most guys have trucks that use high-pressure water to break up the dirt, and then a high-velocity vacuum to suck up all the mud.
“Each authority will have recommendations on how close you can dig to it, what you can do, what you can’t do, and that all gets sent out to you with the DBYD plans.
“If you can’t locate anything that’s on the plan or you need more detailed help, that’s when you call a professional locater in. There’s a hundred-odd locators that can come out and offer you a professional service.”
DBYD is now offering certification for locators working with DBYD asset owners and contractors, which recognises locators with a high level of understanding and practical expertise. Minutoli says the certification will be a “game changer” for the industry, and make it easier to choose a locator with the necessary skills.
Ground penetrating radar
Minutoli recommends utilising ground penetrating radar (GPR) technology for every job.
“GPR has probably been around for about 10 years or more, but it’s only in the last five that it’s become better,” he says. “It’s also getting cheaper – the first one we bought cost $50,000, the last one cost $30,000. GPR is not big in Victoria due to the inconstant soil conditions, compared to what it’s like in say WA, where everyone uses it over there because it is a lot easier to penetrate the soil with the radar waves through the GPR.”
Image 1: Three separate power cables, exposed via hydro excavation by Geelong Cable Locations.
Image 2: DBYD power plans for Sacramento St, Wallington
Image 3: DBYD NBN plans for Sacramento St, Wallington
Image 4: Geelong Cable Locations using ground penetrating radar to locate the underground services at a petrol station.