This is especially notable in and around major cities where the congestion of existing utilities already buried below our footpaths and streets can cause major problems to asset owners wanting to increase their network by installing additional cables/conduits. As time goes on more and more asset owners are realising that the time, money and effort required too install new infrastructure using open cut methods in these areas is not always worth it.

Opening up a street congested with communication, gas, power, water, sewer and drain pipes can be very daunting to even the most experienced contractor, especially when you also consider the potential destruction of numerous driveways finished off with designer pavers or stensilcrete.

Even if the asset owner wants the new conduit installed below all of the existing utilities, there is still the matter of digging past those utilities without causing any damage. In most cases this would require hand digging, as locating existing utilities is never easy, even with Dial Before You Dig and the newest technology in utility location equipment.

Another factor that can increase the difficulty is the fact that some utilities, such as water pipes, can be fairly old and even just disturbing the surrounding ground can fracture the pipe. Coming across bad work practices used in repairs carried out by inexperienced contractors, which fail once uncovered, is another common problem.

It is true that these problems can occur even when digging an entry or exit pit for HDD, but when these pits are only two square metres in size a much smaller amount of ground is disturbed compared to the open trenching of the complete length of a street.

Other factors influencing the installation method being chosen, and which make HDD all the more attractive, are disturbance caused to local residents and destruction of the environment.

One company that understands the benefits of both open trenching techniques and HDD is Sydney-based Infrastructure Constructions (IC). With many of its projects coming from some of Australia’s biggest utility companies, involved in either water, underground power, communications or sewerage, IC has gathered a vast amount of experience with both methods and is often requested by clients to advise on the preferred method of construction in a given situation.

Since its first HDD machine, IC has quickly increased its percentage of conduit installed using HDD against open trenching. Factors contributing to this fact include the request and innovation of the asset owner, the introduction of polyethylene pipe and advances in HDD technology. Over the last twelve months IC has undertaken a wide range of HDD projects covering an array of different product sizes, distances, ground conditions and multiple conduits. IC has six HDD machines available which are used five to six days a week. These range from the JT4020 which is set up for rock drilling, a 2720AT which is a specified rock machine, 13X and 10X Grundodrills and two JT1720s. Along with these are two mud recycling systems and five vacuum trucks.

Reviewing the type and number of projects completed by IC can be quite staggering. Between September 2005 and August 2006 IC completed a total of 59,738 m of pipe installation using both open trenching methods and HDD. Many of these projects required multiple conduits to be installed in the trench or through the bore hole. Throughout the 12 month period 195,856 m of conduit has been installed - averaging out to 3,766 m of conduit installed each week.

The IC Trenchless Division alone has installed 37,682 metres of conduit over the last 12 months with bores ranging from short 10 m shots through to longer 282 m shots. These ranged from the installation of single Ø40mm sewer pipe through to a multiple installation of nine Ø110mm communication conduits over 170 metres under the railway station at Albury.

This gives the Trenchless Division 63 per cent of all work constructed by IC. What makes this even more amazing is that more than 50 per cent of these works have been through solid rock. This percentage is expected to increase even more throughout the following years as HDD technology improves and the confidence of asset owners in this technology increases.