123 Locate It was recently engaged to locate underground pipes and other underground assets at a large industrial plant in Brisbane. Whilst the current plant has been in operation since the mid-1990s, the site itself is quite old, having had a number of prior owners. The underground infrastructure location and type was unknown.

The issues reported from the client:

  • There is an extensive large-volume underground fire system; type of pipe unknown.
  • There is a major fire booster pumping system and a separate sprinkler system. The fire system requires mandatory annual testing of fire line integrity. This year, it failed the test.
  • Fire jacking pumps were randomly running without a known cause.
  •  Some new works were required. However, our client could not design changes without knowing where the original pipes lay.
  •  Originally the fire lines were supplied by river water; it was unknown if the old system had been properly decommissioned.
  • The integrity of existing valves was unknown.
  •  It was unknown if there were old cross-connections between the potable water lines and the fire main and our client suspected some wear.

Scope of works

Asset locating and identification, including valves, of all underground services located within the 4-kilometre area of the plant; followed by leak detection of the fire system.

Identified Site Issues

  • 24-7 site operation
  • Noise
  • Continuous heavy-vehicle traffic and moving plant close to work site
  • Vast work area – 4 km
  • Varying ground types; concrete £1.5mm thick; bitumen over concrete; concrete slabs on top of older slabs; building built over old pipes
  • Old hydraulic drawings missing, inaccurate or changed without updates
  • How to locate water pipes underground when types of pipes unknown (asbestos, ductile and PVC believed to be on site)

Mitigation Strategies

Our work was carried out whilst the large industrial site was fully operational, as the plant operates 24-7. As the fully-operational plant is very busy with trucks entering and exiting continuously through the day, and other plant moving about, it was necessary to have a lookout for the entirety of the project to ensure the safety of our technicians. The Lookout’s sole responsibility is to keep a continuous watch for approaching plant and traffic to warn technicians and their equipment to be moved to a position of safety.

It is not a simple exercise for any underground pipe locator to locate pipes without relevant information. Besides accurate hydraulic drawings, there are numerous external factors that contribute to the underground service locators ability to find underground pipes.

Ambient noise, surface cover, pipe construction, ground or substrate type, depth, length and diameter of pipe, number of valves, joins in pipes, pipe repairs; and water pressure are all factors that affect the frequency and amplitude of the sound wave in the case of leak detection; or the signal strength for GPR and electromagnetic locations, which the technician uses to interpret the location of a leak. Therefore, there is a dramatic increase in the degree of difficulty in locating pipes, then finding the water leaks when there are numerous variables and unknowns.

No single technology or method covers all bases – each has benefits, but with its own shortcomings, meaning that the area will need to be covered repeatedly to build an interpretation of the buried infrastructure. For example, ambient noise affects acoustic detection equipment; and electromagnetic underground cable locator detection (quicker than GPR, therefore less cost to the client) does not work on concrete surfaces, cannot locate non-metallic lines, such as asbestos and PVC, suspected of being present.

Methodology

Starting at know points (hydrants, valves, booster pumps etc) 123 Locate It used a combination of Ground Penetrating Radar, Concrete Scanning, In-Pipe cameras/traceable sondes and Radio Frequency Detection technologies to locate, permanently mark and map the location of the fire mains. This was a tedious task, made harder by limited access. Using concrete cutting equipment and vacuum excavation, any unconfirmed pipes were safely located. The client engaged surveyors to map the locations for future reference.

Once the locations of the pipes were known, 123 Locate It then traversed the whole system with sensitive metal detection equipment, attempting to locate long-covered valves and in-ground hydrants. Many were located. Some old hydrants required replacement by the client.

Old valves were then ‘exercised’ by 123 Locate It technicians, using our mechanical valve tensioners to attempt to make them serviceable. Some were unable to be operated, despite many attempts. These required replacements by the client.

When all possible information on pipe and valve locations were established, 123 Locate It commenced leak testing of the entire fire main system.

Calibrated digital logging pressure gauges were deployed around the system. These gauges are remotely monitored in real time by our technicians on site. When pumped to test pressure, we noted a steady drop in pressure.

Initially, acoustic testing by 123 Locate It technicians identified that old valves at the end of the system were passing, allowing water pressure to escape into the old river feedline, which had not been deleted. These valves were removed and replaced and the old pipes to the river were finally deleted.

The pipe was again pressurised, and still, a constant (but reduced) pressure loss was noted,

123 Locate It technicians deployed digital correlating acoustic loggers to 30 points around the system. This allowed us to check the whole system in one overnight deployment, without the need to leave staff on site, dramatically reducing costs for the client. Several leaks were located on old mechanical fittings on the pipes. These were subsequently rectified by plumbers.

123 Locate It recommended the addition of some new valves to allow isolation of sections of the pipe for maintenance/testing. We also acoustically tested all old valves using pressure differentials to determine in any would not shut off. Some original valves required replacement. Some were cleared of debris by 123 Locate It technicians.

Again, the system was pumped to test pressure and again there was a pressure drop. Step pressure tests of the system were then carried out, shutting off individual sections of the pipe to establish which sections were leaking.

Once leaking sections were identified, acoustic data logging was utilised to locate the last remaining leaks which were rectified.

Outcomes

  • The client now has a fully operable and compliant system.
  • There is full knowledge of the fire mains.
  • Future expansions can be designed with certainty.
  • There are no cross-connections or unused lines.

123 Locate It – underground pipe location services and asset location services.  Only 123 Locate It has the expertise, experience and the technologies to carry out this complex project.

 


 

Let our qualified and experienced underground service locators help you find underground pipes.

Call 123 Locate It on 0421 624 794 or send us an email.