| Term |
Definition |
|
| Tailwater |
The water just downstream from a structure. |
| Target shaft/pit |
See reception/exit shaft/pit. |
| Taxpayer |
Contributions through taxation to utilities to fund supplied services. |
| TBM |
See Tunnel Boring Machine. |
| Teeth |
See bits. |
| Televise |
Process by which a sewer line or lateral is inspected with a Closed-Circuit television camera. |
| Tensile Strength |
The pulling stress in psi that is required to elongate a given specimen to the breaking point. |
| Tensile Strength At Yield |
The measured tensile stress required to initiate permanent deformation in a sample under the conditions described in ASTM D 638. |
| Test Medium |
The fluid or gas inside the main being tested. |
| Thermal Conductivity |
The ability of a material to conduct heat; a physical constant for the quantity of heat that passes through a unit cube of material in a unit of time when the temperature difference is 1?/font> F. |
| Thermal Expansion/Contraction |
The fractional change in length of a material subjected to a unit change in temperature. |
| Thermal stabilizers |
Compounds added to the plastic resins when compounded that prevent degradation of properties due to elevated temperatures. |
| Thermography |
The recording of temperature variations; a technique to assist in the detection of voids around pipelines. |
| Thermoplastic |
A material, such an polyethylene, that will repeatedly soften when heated and harden when cooled. |
| Thermoset |
A material, such as epoxies, that will undergo or has undergone a chemical reaction by the action of heat, chemical catalyst, ultraviolet light, etc., leading to an infusible state. |
| Threading |
The process of installing a slightly smaller pipe or arch within a failing drainage structure. |
| Throttle |
Controls power, speed. |
| Thrust |
Force applied to a pipeline or drill string to propel it through the ground. |
| Thrust block |
A manual or remote operated locking mechanism that engages stations in the track to provide a thrusting base for the machine to advance and retract. |
| Thrust block pin |
See dogs. |
| Thrust boring |
A method of forming a pilot bore by driving a closed pipe or head from a thrust pit into the soil which is displaced. Some small diameter models have steering capability achieved by a slanted pilot-head face and electronic monitoring. Back reaming ma |
| Thrust jacking method |
Method in which a pipe is jacked through the ground without mechanical excavation of material from the front of the pipeline. |
| Thrust package |
The bottom section of a split boring machine containing the cylinders and thrust block. |
| Thrust pit |
See drive pit. |
| Thrust Ring |
A fabricated ring that is mounted on the face of the jacking frame. It is intended to transfer the jacking load from the jacking frame to the thrust bearing area of the pipe section being jacked. |
| Thrust/travel controls |
Those controls that control the advance and retraction of the tool. |
| Tile (VT) |
Used to describe products (sewer pipe and block) manufactured from fired hydrous alumina silicate clay. |
| Tool diameter (d) |
Maximum diameter of tool body |
| Tool length |
Distance between tip and end of tool, not including whip hose. |
| Torque |
The rotary force available at the drive chuck. |
| Torque limiter |
A rotary slip clutch used to protect the final drive. |
| Track |
A set of longitudinal rails mounted on cross members that support and guide a boring machine. |
| Track brake |
A mechanical device to provide a limited resistance to movement between the machine and the track. |
| Track pins |
Steel pins to be driven through holes in the track into the base of the pit. |
| Track roller |
See cam follower. |
| Transmission |
A gear reduction unit located between the power source and final drive. |
| Transportation System |
the excavated spoil from the tunnel face to the surface. |
| Travel |
Changes travel speed. |
| Trench box |
A preconstructed set of side plates and adjustable cross members to prevent the walls of the pit from collapsing. |
| Trenching |
See open cut or conventional trenching. |
| Trenchless technology |
Techniques for utility line installation, replacement, rehabilitation, renovation, repair, inspection, location and leak detection, with minimum excavation from the ground surface. |
| Trunk sewer |
A sewer into which at least two branch sanitary, combined or stormwater sewers connect. It conveys the flow to the Interceptor sewer. The trunk sewer is the longest connection sewer in any drainage basin. Also sometimes known as a "main" sewer. |
| Tuberculation |
Localized corrosion at scattered locations resulting in knob like mounds. |
| Tunnel |
An underground conduit, often deep and expensive to construct, which provides conveyance and/or storage volumes for wastewater, often involving minimal surface disruption. |
| Tunnel boring machine (TBM) |
(1) A full-face circular mechanized shield machine, usually of Man-Entry diameter, steerable and with a rotary cutting head. For pipe installation it leads a string of jacked pipes. It may be controlled from within the shield or remotely. (2) (Mole, |
| Tunneling |
A construction method of excavating an opening beneath the ground without continuous disturbance of the ground surface and of large-enough diameter to allow individuals access and erection of a ground support system at the location of material excava |
| Two speed control |
A hydraulic valve that increases the flow of oil to the cylinders to provide rapid low power motion of the machine. |
| Type "K" barrier rail |
A portable concrete fence or barrier that is made in the vague shape of the letter "K". |
