By Anthony Johnstone, Access Detection
With the new AS5488 standards completed and in some cases already been utilised in the industry, I have been asked many times when training what these standards mean to a locator contractor.
With the new AS5488 standards completed and in some cases already been utilised in the industry, I have been asked many times when training what these standards mean to a locator contractor.
The most important thing about AS5488 is that it gives the locator contractor, the excavation operator and the surveyor a clear understanding of what is below the ground and how this is interpreted. In fact it is a good communication tool between all parties.
The standards for markings are split up into four classes QL-(A) sighted, QL-(B) traced, QL-(C) aligned from surface features, QL-(D) any other method. This allows all operators on the project to understand the accuracy of the site location and map data when carrying out any kind of planning and excavation works. It can reduce costs by pre planning on projects
For example a class (A) marking indicates to the excavation operator that at that point the locator contractor has used a detection device, has excavated down usually with vacuum excavation and has identified the service at that point with a true depth by physically measuring the pipe.
A word of warning when a (A) class marking is found along a pipe or cable route it is only at this point that you can be assured of the position and actual depth of the pipe or cable. It does not allow for variances of the cable route (twists or change in directions and or depth) between two points.
Another factor is that although you have excavated and identified a cast iron pipe, this does not always assure it is a water or sewer pipe. An area in an old estate was mapped, a galvanised pipe was identified through an excavation and was marked as water class (A). This pipe turned out to be an old conduit for the electricity lighting an easy and sometimes dangerous trap if you are not careful with tracing point to point.
A further example is a contractor using GPR to locate an area found two targets but could not confirm if the target was either water or sewer as they ran close together. Unlike a traditional pipe and cable locator were you connect to an actual point for example a hydrant and trace to another hydrant, GPR does not physically hook up to a service so unless a clear visual identification can be seen and a clear indication of the targets running from point to point vacuum excavation would be recommended to bring this type of locate to a class (A). Of course traditional pipe & cable locators can also give you erroneous readings and an operator should be clear in each instruments strengths and training is a key part of the getting the best of these standards.
There are no standards for the type of equipment that can be used to detect services, anything from divining rods, pipe & cable locators to complex GPR antenna arrays can be utilised. The equipment and training dictates the quality achieved. Most professional companies that work to these standards will have an array of equipment at their disposal which can accurately identifies these services.
If you are looking at utilising companies that specialise in the new AS5488 standard a good place to start would be www.nulca.com.au this is an association dedicated to providing professional standards in locating, training and technology, quite a few companies in the association have already implemented the standard.
As a supplier and trainer of detection equipment we are able to assist our clients in selecting the best equipment for their needs. We offer both in house training or can offer fully accredited Australian industry recognised locator courses for our clients.
