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Search the ASTT technical archive.
Papers, case studies, standards and webinars covering trenchless methods across Australia and New Zealand.
459 results (298 ASTT documents, 161 ISTT technique descriptions) · showing 361–384
Investigation / Assessment
In addition to the work undertaken to actually install or rehabilitate an underground utility, there are significant investigation, inspection and planning phases that must be accomplished before the detailed design work and the construction work can be undertaken. This category of trenchless technologies is concerned…
ISTT
Joint Grouting
Grouting can reduce or eliminate inflow and infiltration of sewer lines and manholes by stabilizing and sealing defects and leaky joints together with the adjacent soil. This is most effective where the defects are not severe and the surrounding soil is stable enough to retain the grout. Grout can be applied over a…
ISTT
Keyhole Drilling
The Keyhole Drilling method uses the trenchless techniques of coring, potholing and horizontal directional drilling (HDD) to install pipes underground. A core is cut out of the road, a pothole is excavated, and the drilling machine is inserted into the pothole. A horizontal pilot bore is drilled, then the pipe is…
ISTT
Laser / LIDAR
The detailed pipeline dimension can be obtained by the laser profiling in open pipes and the sonar profiling in water filled pipes. Dimensional analysis using these technologies reveals and quantifies absolute diameters, ovality, offsets, cracks and discontinuities in a pipe structure that effect the life and…
ISTT
Lateral / Small Pipe Inspection
Small pipe inspection can be accomplished using nozzle cameras that are pushed through the pipe to be inspected or cameras attached to other devices that are inserted in the pipe to be studied. The image from the camera is typically forward-facing along the pipe and automatic orientation of the image with respect to…
ISTT
Lateral Junction CIP Repair
(Also known as CIP(P) Lateral Connection Repair, Connection Liner, Cured in Place Repairs (CIPR) for local defects and lateral connection repairs. Sometimes referred to as Top Hats.) This uses Cured-in-Place (CIP) technology to create a lateral junction liner that is designed to repair, seal and reinforce pipe…
ISTT
Leak Detection (Pressure Pipes)
There are a number of methods for surveying and locating leaks in pressurized pipes. Methods vary from simple hand-held acoustic receivers operated above ground to in-pipe, free-swimming leak detectors. The system most suited for the job will depend on the type of utility service to be investigated, the area of…
ISTT
Leak Signature Detection
The most common leak signature detection method tracks the acoustic signature of a leak (see acoustic detection). However, there may be other changes brought about by leakage in a pipe system that can be observed or searched for. Examples include vegetation changes above a leaking water pipeline or chemical traces in…
ISTT
Loose-fit or Close-fit Lining
Some lining approaches may be designed to be loose-fit or close-fit according to project needs. Lining approaches that were developed to provide only close-fit solutions are grouped separately. A loose-fit liner is one for which the outside diameter of the inserted liner is significantly smaller than the inside…
ISTT
Mainline Pipe / Tunnel Inspection
The most common visual pipe inspection devices are Closed Circuit Television (CCTV) video cameras. These cameras are mounted on small tractor devices or sleds and are driven or pulled through the sewer to inspect repairs and to assess the condition of sewer systems. The basic CCTV system includes the camera and…
ISTT
Manhole / Chamber Inspection
Manhole/chamber inspection can be accomplished using person-entry techniques but, to avoid the safety protocol implications of confined space entry, remote inspections using techniques such as zoom cameras or laser surveys may be used to gather initial data.
ISTT
Manhole Rehabilitation
Introduction While not generally termed “trenchless technology”, manhole rehabilitation methods use minimal excavation, if any, and minimise the surface disturbance, disruption of street activities and work in confined spaces. The technologies for rehabilitating manholes are used to renovate deteriorating…
ISTT
Maxi-HDD
Maxi HDD involves large-scale equipment for long-distance and/or large diameter installations. Drilling/Steering Mechanism For smaller bores in soil, the slant-face spade bit is most commonly used as indicated in the general method description. For larger and deeper bores and in rock and hard soils, a different…
ISTT
Mechanical Seals
Mechanical seals are available to repair pipe defects at joints or over short distances along the pipe. Mechanical seals are used to seal defective pipe joints and other pipe defects. Mechanical seals typically consist of a rubber gasket sized to the dimensions of the pipe and secured by stainless steel retaining…
ISTT
Melt-in-Place-Pipe (MIPP)
In this category of close-fit lining, a principally thermal approach to creating the lining is used by what is termed a “Melt-in-Place-Pipe” (MIPP) lining process. This process is applicable for both water mains and sewers. The process involves winching a liner tube, made from an intimately woven fabric of…
ISTT
Method scale
As indicated in the general method description, HDD principles are used for installations of vastly varying sizes and distances. The change in scale from a small street crossing for a fiber optic cable to the installation of a large pipeline across a major river requires major changes in the equipment used, the…
ISTT
Midi-HDD
As the name implies, midi-HDD represents a mid-range of applications for HDD.
ISTT
Mini-HDD
Mini-HDD represents the smallest scale of HDD applications involving compact equipment installing small diameter pipes or cables over short distances (such as across roadways or residential yards).
ISTT
Mini-trench / Micro-trench
Generally mini-trench and micro-trench methods of underground pipe or cable installation are categorised as trenching methods with a limited surface impact. The narrow trenches significantly minimise the amount of excavated material and surface reinstatement. In addition, the operation avoids the normal hazards…
ISTT
Mole Ploughing
Mole ploughing and narrow trenching are not trenchless technologies but they both create narrow temporary trenches for installing small diameter services that minimize the adverse impact associated with traditional underground construction methods requiring wide trenches. These two techniques use plows, cutter chains,…
ISTT
Muck Cart
A muck cart is a traditional way of moving excavation spoil from the tunnel face to the starting shaft or entry point. Typically the cart is moved on rails and the tunnel is preferably excavated with a slightly uphill grade to aid in moving the loaded muck cart. Muck car systems are used in person-entry size tunnel…
ISTT
New Installation
This class of methods is focused on the installation of new utilities using directional (steerable) drilling, microtunneling and other trenchless techniques. Also, for completeness, other methods of avoiding or limiting surface disturbance are introduced here under "allied techniques."
ISTT
Non-adhered hose
In this inserted hose lining variant, the inserted hose is laid loosely within the host pipe. When the pipe is depressurized temporarily – for maintenance or due to some unforeseen circumstance – the hose liner is likely to deflate within the host pipe and it is necessary that it should be able to…
ISTT
Non-Person-Entry
A non-person-entry scale for pipe jacking represented an important part of the traditional definition of microtunnelling. The limitations presented by non-person-entry do have important implications for the tunnelling process - most importantly that there is no access to the face for changing cutter heads and…
ISTT