Back in the July issue T&TI’s Trenchless Technology focus highlighted various new installation techniques within the No-Dig family. Whilst the new installation side of trenchless technology may often appear to be the ‘sexy’ side of the industry with the high-tech equipment, laser/electronic guidance systems, com-puter controls and everything else that comes with it, there is the other side of the industry that, although not as ‘sexy’, is equally as important and covers several major growth areas. This is the asset management, rehabilitation and replacement sectors.
With increasing emphasis by utility companies, local authority owners and service providers on ensuring pipeline networks are fit-for-purpose, there is an in-creasing demand for technologies that will enable these organisations to fulfil their obligations in these work sectors in the most economic, technically feasible and yet socially acceptable way. The following is an overview of some of the more recent developments, but probably not all, in the field of asset management, as without this technology engineers would have difficulty in understanding where the problem that needs to be solved is located in the first place.
Asset management
Condition assessment of pipelines is a science in itself, with the various standard CCTV, lateral connection and 360° survey systems as well as sonar systems and the assessment software and, often individual, assessment requirements that goes with it. As such an extensive topic area in itself this will not be covered in this issue.
Over the past few years, and particularly the past 18 months or so, there have been some major innovations and advances in the field of asset management in terms of locating and tracing.
One of the aspects of asset management that is becoming increasingly important with the wider use of trenchless technology in general is establishing where any existing asset is. For many years one of the consis-tent complaints from buried service contractors and engineers, and particularly users of trenchless technology, has been that existing pipeline and cable network plans are not accurate enough.
Whilst this situation is improving slowly over time, on any particular worksite it is still wise to map the buried services before starting a project, whether this is for new installation or rehabilitation. Knowing where the target service is or will run is important as much due to its potential proximity to other services as for its own sake. When pipe bursting for instance, if a pipeline being replaced is closer to an adjacent service in reality than it is on the plan, there is potential for significant, and expensive, third party damage.
To avoid this situation there are several remote sensing systems that can be used to accurately determine the route and depth of existing services. These include cable/pipe tracing/locating systems and ground probing radar. These use inherent or generated electromagnetic signals to pinpoint buried services.
Pipe and cable tracers, as they are commonly known, comprise an antenna that is designed to respond to the electro-magnetic effects created by a current passing through a cable or to that generated by a signal generator coupled to a metallic pipe being traced. Where plastic pipe is being traced a signal generating pipe probe or sonde can be passed through a pipe from a known access point and followed on surface.
One of the more recent launches of equipment into this sector was from Charles Machine Work (CMW), which manufactures Ditch Witch underground construction equipment. The Ditch Witch 150R/T/B is an easy-to-use, inexpensive pipe and cable avoidance system that detects common, active, passive, and beacon frequencies. Consisting of a receiver, transmitter, and an optional beacon, the 150R/T/B system is configured with the customer’s choice of frequency at the time of purchase. Available frequencies are 640Hz, 30kHz and 83kHz. The new 150R/T/B system has been designed with the small contractor in mind.
From Cable Detection, the EziSYSTEM claims to be a step up from the older more traditional CATs in the marketplace. Products making up the range include the EziCAT 100, The EziCAT 200, the EziTRACE and a variety of accessories to enable operators to trace the more difficult services. These products have only been on the market a short time but are already generating a lot of interest across the utilities, construction and surveying sectors. Key features include: Automatic Pinpointing – for faster location of services; four tracing modes for more flexibility on site (Power, Radio, 33kHz and 8kHz); switch on at maximum sensitivity and in power mode; and depth indication with the EziCAT 200 in conjunction with the EziTRACE in 33kHz mode.
RIDGID has also launched a new line of locating equipment to meet the demanding needs of the locating professional. Built to make even difficult locates easy, SeekTech is the only line locator that uses omni-directional antennas, guidance arrows and an easy to read mapping display to quickly and accurately locate the target. The antennas power the large mapping display which provides all the information required to locate underground utilities. Proximity Signal and Signal Strength indicators help the operator centre the locator closer to the target for more confident locates.
Available Active Line Trace Frequencies include 128Hz, 1kHz, 8kHz and 33kHz as well as Sonde Frequency options of 16Hz, 512Hz and 33kHz. The Continual Depth facility increases productivity by showing depth changes in real time and with the Current Strength capability the unit identifies current on the target line for faster diagnosis of complex locates. There is also a Mapping Display which ‘virtually’ maps the utility to help guide operators down the line, which shows signal distortion and line turns in real time. The system can also operate with a Passive Power Trace at 50Hz and 60Hz as well as with a Passive Radio Trace at frequencies of <4kHz, 4kHz-15kHz and 15kHz-38kHz.
Developed from equipment originally aimed at the market for precise mapping of HDD bores, PipeTrack is a new mapping system from UK-based Infotec. PipeTrack offers accurate, simple and flexible 3D mapping of a pipeline providing pinpoint data of not just its route in plan view but also its depth, to an accuracy of 0.25% in the horizontal plane and 0.1% in the vertical plane from a single pass survey, a vital consideration given current thinking on asset management and reme-diation of utilities.
Designed to complement more conventional and traditional pipeline locating technologies, the unit is easy to use and requires no tracing or tethering or umbilical connection to the surface, yet gives the precise ‘centreline’ position of the pipeline being surveyed.
Using the PipeTrack unit, up to 500m of pipeline can be mapped in a single stretch in less than one hour, minimising service interruption. The PipeTrack unit records data autonomously using an on-board storage system which means no restrictions on depth of working or length of survey.
One other aspect that might be mentioned here is that all of these asset management tools are not only applicable to utility location for shallower works and projects, but they also have a role to play in large bore tunnelling works, particularly those in urban areas. PipeTrack was recently employed in London to locate and accurately plot buried services above the proposed route of a new rail tunnel, so that planners could accurately predict where any conflict might occur and act accordingly.
In terms of ground probing radar, Italy-based manufacturer, IDS Ingegneria dei Sistemi recently introduced a new dual frequency antenna to the ground investigation and utility location system known as the IDS Detector Duo. Using dual search frequencies of 250MHz and 700MHz, the new unit offers simultaneous display of deep and shallow targets on the one display.
Easy to interpret real time results locate the exact position of pipes, cables and bedrock, using a system that is designed to be compact, easy to transport and deploy.
The dual antennae means there is no need to swap antenna or cover the same site twice to achieve the required results making for a very efficient survey procedure.
GPR
One of the more recent entrants into the GPR market is Ditch Witch with its new 2150GR ground penetrating radar which is designed to detect and locate both metallic and non-metallic pipes and cables to depths of up to 6m, depending on soil conditions and antenna selection. With the ability to survey in both forward and reverse directions, and with survey speeds that are claimed to be up to four times faster than competitive systems, the Subsite 2150GR can map subsurface structures very efficiently.
Whilst offering digitally controlled radar for faster survey speeds and better images the earth-engaged antenna provides better contact on uneven terrain and reduces signal loss. Two interchangeable antenna options are available to customise the unit for project conditions. The system can also operate in a variety of languages including English, French, German, Spanish, Italian, Portuguese and Chinese, and surveys a 500mm wide path using antenna frequencies of 250 or 700MHz. Collected data is stored directly to a laptop hard drive. With the 250MHz antenna depth of probe is between 0.2 and 2.5m, with a maximum depth capability of 6m depending on soil conditions. With the 700MHz antenna the working depth is be-tween 0.1 and 1.5m, with a maximum soil dependent depth of 2.5m.
Vacuum excavation
Another area of the asset management sector that has seen some major growth recently is that of Vacuum Excavation. Whilst these systems have been used extensively for water and slurry removal in a site support role, these systems can also use high pressure air or water jets to breakdown soils in a very small area. The spoil is then sucked away with a vacuum into a holding tank from which it can be off loaded and dumped or recycled as required. The use of these systems in asset management has been largely based around the excavation of small potholes to confirm the underlying buried service structure and route and to excavate around existing services when accessing target buried services without causing damage to adjacent ones.
Whilst the industry sector is becoming increasingly more established across the globe some manufacturers have recently made major changes in the way they approach the market.
For example Vermeer Manufacturing Company and McLaughlin have joined forces to introduce a new range of vacuum excavators that are capable of hydro-excavation, retrieving both wet and dry spoil. The most recent launches have included the 946 l, V250 unit, which is claimed to be a lower cost vacuum excavator that is suitable for contractors and municipalities looking to identify and locate utilities; the V500LT small footprint, 1,893 l capacity unit, which at full vacuum operates at up to 16.3m3/min, and the V500LTHD, which offers the same features as the V500LT but is equipped with a 36.5kW diesel engine for increased power in the same small package to offer a vacuum blower pump that delivers 26.9m3/min. The MTS range of vacuum systems has been manufactured in Germany for some time, but recently in the UK, U Mole Ltd add the range to its existing Vac-Tron vacuum excavation capability. The MTS family comprises the DINO range of vacuum excavation systems that includes the DINO 2, the DINO 3 and the DINO 4 models. Each is available in a standard and ‘MEGA’ version with single or double vacuum generation turbines respectively.
As well as these ‘standard’ models U Mole also offers the MTS DINO 4 MEGA VAC. This is a high power (400kW) system that is designed specifically for the more arduous tasks sometime required of vac uum excavation systems, such as removal of heavier spoils or work at greater depths.
The standard units offer: a high maintainable suction from 25,000m3/hour up to 36,000m3/hour air volume; up to 50% vacuum of between 17,000 and 34,000Pa negative pressure and large spoil capaci-ties of up to 12m3. To show just how quickly the vacuum excavation market is moving one of U Mole’s clients John Mee Construction Ltd recently doubled it Vac-Tron based Vac.Ex. fleet.
TT UK offers Suction Excavation Technology that has been specially designed for excavation and specialist construction activities in urban and suburban areas. It assures instant operability and fast excavation without the risk of affecting or damaging any unforeseen buried utilities. The unit offers utility contractors excavation capacities of around 45m3 day based on a 26t Suction Excavator with a 7m3 container.
Of course once the position of the service in question is known and its condition established, a decision then has to be made about how to deal with it. Normally this means either replacing it or renovating it.
Now the engineer knows where his problems are the decision now has to be made as to how to solve it.
The latest developments in replacement and renovation technologies that are now available to achieve this will be covered in the next issue of T&TI.
The PipeTrack system, from Infotec being launched from a manhole The Ditch Witch 150R/T/B pipe and cable avoidance tool The new IDS Detector Duo ground probing radar system The Subsite 2150GR ground probing radar system from Ditch Witch The new V500LT vacuum excavation unit from Vermeer/McLaughlin An MTS Dino 3 vacuum excavation unit operating in the UK Suction Excavation Technology from TT UK
