Glossary of Terms

Glossary of Terms used with permission from the North American Society for Trenchless Technology. For the full listing of terms, please click here.

Abrasion
Removal of material due to a frictional contact.

Adapter Ring
In microtunneling, a fabricated ring usually made from steel that serves to mate the microtunneling machine to the first pipe section. This ring is intended to create a waterproof seal between the machine and the spigot of the first joint.

Additive
A substance added in a small amount, usually to a fluid, for a special purpose such as to reduce friction, corrosion, etc.

Advance
The motion of the machine in a direction toward the face wall of the entrance pit.

Advance rate
Speed of advance of a pipe jack or other trenchless installation through the ground, generally expressed as either millimeters per minute or meters per day.

Agreement
The written agreement between the owner and the contractor covering the work to be performed; the contract documents are attached to and made a part of the agreements. Also designated as the contract.

Angle of Repose
The angle which the sloping face of a bank of loose earth, gravel, or other material, makes with the horizontal.

Annular filler
Material for grouting the annular space between the existing pipeline and the lining system.

Annulus
Free space between the existing pipe and any lining.

Approval
Accept as satisfactory.

ASCE
American Society of Civil Engineers.

Asset
A valuable resource.

ASTM
American Society of Testing and Materials, technical organization formed for the development of standards on characteristics and performance of materials, products, systems and services, and the promotion of related knowledge.

Auger
A flighted drive tube having hex couplings at each end, to transmit torque to the cutting head and transfer spoil back to the machine.

Auger boring
A technique for forming a bore from a drive pit to a reception pit, by means of a rotating cutting head. Spoil is removed back to the drive shaft by helically wound auger flights rotating in a steel casing. The equipment may have limited steering capability.

Auger machine
A machine used to drill earth horizontally by means of a cutting head and auger or other functionally similar device. The machine may be either cradle or track type.

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Back reamer
A cutting head attached to the leading end of a drill string to enlarge the pilot bore during a pull-back operation to enable the carrier or sleeve or casing to be installed.

Backstop
Reinforced area of the entrance pit wall directly behind the track.

Band
A ring of steel welded at or near the front of the lead section of casing to cut relief and strengthen the casing.

Barrel
The vertical section in a manhole between the cone and the bench wall.

Base
The slab structure which supports a manhole.

Bentonite
Colloidal clay sold under various trade names that form a slick slurry or gel when water is added. Also known as driller’s mud. See drilling fluid.

Berm
The space between the toe of a slope and excavation made for intercepting ditches or borrow pits.

Bid
The offer or process of the bidder submitted on the prescribed form setting forth the prices for the work to be performed.

Bidder
Any person, firm, or corporation submitting a bid for the work.

Biological Corrosion
Corrosion that results from a reaction between the pipe material and organisms such as bacterial, algae, and fungi.

Bits
Replaceable cutting tools on the cutting head or drill string.

Bonds
Bid, performance and payment bonds and other instruments of security furnished by the contractor and his surety in accordance with the contract documents and in accordance with the law of the place of the project.

Bore
A generally horizontal hole produced underground primarily for the purpose of installing services.

Boring
(1) The dislodging or displacement of spoil by a rotating auger or drill string to produce a hole called a bore. (2) An earth-drilling process used for installing conduits or pipelines. (3) Obtaining soil samples for evaluation and testing.

Boring machine
A mechanism to drill earth.

Box
See female hex connector.

Branch sewer
A sewer into which at least two sanitary, combined or storm water sewers connect.

Breakout
Controls the joint make and/or break mechanism.

Budgets
An amount of money needed or allocated for a specific use.

Building combined sewers
A small diameter pipe that conveys both wastewater and drainstormwater from a single property to a combined sewer.

Building sanitary drain
A small diameter pipe that conveys wastewater from a single property (e.g. domestic home) to a sanitary sewer.

Building Sewer
The conduit which connects building wastewater sources, to the public or street sewer, including lines serving homes, public buildings, commercial establishments, and industry structures.

Bypass
An arrangement of pipes and valves whereby the flow may be passed around a hydraulic structure or appurtenance. Also, a temporary setup to route flow around a part of a sewer system.

Bypass Pumping
The transportation of sewage which flows around a specific sewer pipe/line section or sections via any conduit for the purpose of controlling sewage flows in the specified section or sections without flowing or discharging onto public or private property.

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Caisson
A watertight box or cylinder used in excavating for foundations or tunnel pits to hold out water so concreting or other construction can be carried.

Can
A principal module which is part of a shield machine as in microtunneling or tunnel boring machines (TBMs). Two or more may be used, depending on the installation dimensions required and the presence of an articulated joint to facilitate steering.

Capital
A sum of money used to implement projects.

Carrier pipe
The tube which carries the product being transported and which may go through casings at highway and railroad crossings. It may be made of steel, concrete, clay, plastic, ductile iron, or other materials.

Cased bore
A bore in which a pipe, usually a steel sleeve, is inserted simultaneously with the boring operation. Usually associated with auger boring or pipe jacking.

Casing
A pipe used to line bore holes through which a pipe(s) called carrier pipes or ducts are installed. Usually not a product pipe.

Casing adapter
A circular mechanism to provide axial and lateral support of a smaller diameter casing than that of the casing pusher.

Casing pipe
A pipe installed as external protection to a product pipe.

Catch basin
A small buried structure to divert overland storm water flow into sewer flows.

CCTV
Closed circuit television used to carry out internal inspection and survey of pipelines.

Centerline
The vertical distance between the center of the drive chuck and the ground plane.

CFM
Cubic Feet per Minute; a measure of flow volume. One CFM equals 0.472 liters per second.

Change Order
A written order to the contractor authorizing an addition, deletion or revision in the work, within the general scope of work of the agreement, authorizing an adjustment in the agreement price or agreement time.

Channel
A prepared flow route within the bench of a manhole that conveys the incoming flow to the downstream pipe.

Chemical grouting
Method for the treatment of the ground around a shaft or pipeline, using non-cementitious compounds, in order to facilitate or make possible the installation of an underground structure.

CIP
Cast Iron Pipe

Cleaning
An action of a boring machine to remove spoil that occurs when the auger is rotating while axially stationary.

Closed face
The ability of a tunnel boring machine to close or seal the facial opening of the machine to prevent or slow the entrance of soils into the machine. Also may be the bulk heading of a hand dug tunnel to slow or stop the inflow of material.

Closed-Circuit Television Inspection (CCTV)
Inspection method utilizing a closed circuit television camera system with appropriate transport and lighting mechanisms to view the interior surface of sewer pipes and structures.

Cofferdam
A barrier built in the water so as to form an enclosure from which the water is pumped to permit free access to the area within.

Cohesive Soil
A soil that when unconfined has considerable strength when air-dried, and that has significant cohesion when submerged.

Collapse
Critical failure of a pipeline when its structural fabric disintegrates.

Collection system
A network of sewers which serves one or more catchment areas.

Collector sewer
A sewer located in the public way collects the wastewaters discharged through building sewers and conducts such flows into larger interceptor sewers and pumping and treatment works. (Referred to also as "street sewer.")

Colloidal
Very small insoluble non diffusible particles that remain in suspension.

Combined sewer system
A single network of sewers designed to convey storm water as well as sanitary flows.

Compaction
The densification of a soil by means of mechanical manipulation.

Compressed air method
General term which, in trenchless technology, refers to the use of compressed air within a tunnel or shaft in order to balance ground water and prevent ingress into an open excavation.

Compression gasket
A device which can be made of several materials in a variety of cross sections and which serves to secure a tight seal between two pipe sections (e.g., "O" rings).

Compression ring
A ring fitted between the end bearing area of the bell and spigot to help distribute applied loads more uniformly. The compression ring is attached to the trailing end of each pipe and is compressed between the pipe sections during jacking.

Conduit
A broad term that can include pipe, casing, tunnels, ducts or channels. The term is so broad that it should not be used as a technical term in boring or tunneling.

Cone
The section between the top of a manhole wall and chimney or the frame. The diameter of the manhole is reduced over the cone section to receive the frame. The cone section may be concentric or eccentric.

Consolidation
The gradual reduction in the volume of a soil mass resulting from an increase in compaction.

Contract documents
The Agreement, Addenda, Instructions to Bidders, Contractor's Bid, the Bonds, the Notice of Award, the General Conditions, the Supplementary Conditions, Special Conditions, Technical Conditions, the Specifications, Drawings, and Drawing Modifications.

Contract price
The total moneys payable to the contractor under the contract documents.

Contract time
The number of calendar days stated in the agreement for the completion of the work.

Contractor
The person, firm or corporation with whom the owner has executed the agreement.

Control Console
An electronic unit inside a container located on the ground surface that controls the operation of the microtunneling machine. The machine operator drives the tunnel from the control console. Electronic information is transmitted to the control console.

Control lever
A handle that activates or deactivates a boring machine function.

Conventional tunnelling
Methods of tunnel construction ranging from manual excavation to the use of self propelled tunnel boring machines. Where a lining is required bolted segmental rings are frequently used.

Corrosion
The destruction of a material or its properties because of a reaction with its (environment) surroundings.

Corrosion Resistance
Ability of a material to withstand corrosion in a given corrosion system.

Corrugated pipe
Pipe with ridges (corrugations) going around it to make it stiffer and stronger. The corrugations are usually in the form of a sine wave a+B181nd are usually made of galvanized steel or aluminum.

Cover
The lid at the top of the manhole which can be removed when access to the interior of the manhole is required.

Cracks
Fracture lines visible around the circumference and/or along the length of a sewer.

Crew
The number of persons required for the performance of work at a site as determined by the contractor in response to task difficulty and safety considerations at the time or location of the work.

Critical sewers
Sewers with the most significant consequences in the event of structural failure.

Cross members
The lateral supports under the track of a boring machine.

Crossing
Pipeline installation in which the primary purpose is to provide one or more passages beneath a surface obstruction.

CSO
Combined Sewer Overflow; a hydraulic relief point within combined sewer systems designed to discharge excess flows during wet weather to receiving waters.

Cut and Cover
See Open Cut.

Cutterhead
Any rotating tool or system of tools on a common support that excavates at the face of a bore. Usually applies to mechanical methods of excavation.

Cutting bit (cutter head)
The actual teeth and supporting structure that is attached to the front of the lead auger, drill stem or front face of the tunnel boring machine.

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Data logger
(Also field data logger.) Keyboard-type device used to electronically record inspection data.

Dead man
A fixed anchor point used in advancing a saddle or cradle type boring machine.

Debris
Accumulation of material consisting of organic (human waste, food wastes, etc.), (sand, gravel, wood, etc.), grease or roots.

Dewater
Any method used to lower the water table in the vicinity.

Diameter of reamer (d2)
Largest diameter of reamer.

Diameter of standard bit (d1)
Maximum outside diameter of standard bit.

DIP
Ductile Iron Pipe

Directional drilling
A steerable system for the installation of pipes, conduits and cables in a shallow arc using a surface launched drilling rig. Traditionally the term applies to large scale crossings in which a fluid-filled pilot bore is drilled using a fluid-driven machine.

Discharge point
The point where the flows in a sewer are discharged.

Discount
A reduction in the calculated price.

Diverting
Modifying the normal wastewater flow to allow access to some specific sewer structure; often includes bypass pumping.

Dogs
Moveable protrusions in the thrust block that engage holes or blocks in the track.

Drill string
1) The total length of drill rods/pipe, bit, swivel joint etc. in a drill bore-hole. 2) System of rods used with cutting bit or compaction bit attached to the drive chuck.

Drilling fluid/mud
A mixture of water and usually bentonite and/or polymer continuously pumped to the Cutting Head to facilitate cutting, reduce required torque, facilitate the removal of cuttings, stabilize the borehole, cool the head and lubricate.

Drive/entry shaft/pit
Excavation from which trenchless technology equipment is launched for the installation of a pipeline, conduit or cable. It may incorporate a thrust wall to spread reaction loads to the soil.

Drop connection manhole
A manhole in which the influent pipe enters from above the effluent invert depth. If the drop occurs in the manhole itself, it is called an "internal" drop manhole. If the drop occurs a few feet upstream of the manhole, it is referred to as a "external” drop manhole.

Drop manhole
If the upstream pipe is at a greater elevation than the manhole invert then two inlet connections to the manhole are made. One is through the wall at the same grade as the upstream pipe, the other is at the invert so to direct flows through the channel.

Dry bore
Any drilling or Rod Pushing system not employing drilling fluid in the process. Usually associated with guided Impact Moling, but also some rotary methods.

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Earth piercing
(1) Term commonly used in North America as an alternative to impact moling. (2) The use of a tool which comprises a percussive hammer within a suitable casing, generally of torpedo shape. The hammer may be pneumatic or hydraulic.

Earth pressure balance (EPB) machine
Type of microtunneling or tunneling machine in which mechanical pressure is applied to the material at the face and controlled to provide the correct counter-balance to earth pressures in order to prevent heave or subsidence.

Earth pressure balance shield
Mechanical tunnelling shield which utilizes a full face to support the ground in front of the shield and usually employs an auger flight to extract the material in a controlled manner.

Easement
A liberty, privilege, or advantage without profit which the owner of one parcel of land may have in the hand of another. In this agreement, all land, other than public streets, in which the owner has sewer system lines or installations.

Easement Access
Areas within an easement to which access is required for performance of work.

Effluent
A generic term used to indicate the relative strength of sewer flows; from storm water to wastewater to industrial effluent, for example.

Embankment (or fill)
A bank of earth, rock or other material constructed above the natural ground surface.

Emergency controls
Those controls that stop power to machine or components.

Emergency repair
A repair that must be made while the main is pressurized, or flowing.

Emergency stop
A red manually operated push button that, when activated, stops all functions of the machine.

Engineer
The person, firm or corporation named as such in the contract documents; the "Engineer of Record".

Entrance pit
1) An opening in the earth of specified length and width for placing the machine on line and grade. 2) See boring pit.

Entry ring
See Launch Seal

Entry/exit angle
Angle to the ground surface at which the drill string enters or exits in forming the pilot bore in a directional drilling/guided boring system.

Environment
The surroundings or conditions (physical, chemical, mechanical) in which a material exists.

EPA
United States Environmental Protection Agency

EPB
Earth Pressure Balance

Epoxy
Resin formed by the reaction of bisphenol and Epichlorohydrin.

Erosion
Deterioration of a surface by the abrasive action of moving fluids. This is accelerated by the presence of solid particles or gas bubbles in suspension. When deterioration is further increased by corrosion, the term "Corrosion-Erosion" is often used.

Exit pit
An opening located at the exit of the cutting head or casing.

Exit shaft
See Reception Shaft.

Expander
A tool which enlarges a bore during a pull-back operation by compression of the surrounding ground rather than by excavation. Sometimes used during a thrust boring process as well as during directional drilling/guided boring pull-back.

Extension track
An additional section of track used in front of the master track.

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Face
Wall of the entrance pit into which the bore is made.

Face stability
Stability of the excavated face of a tunnel or pipe jack.

Feet
US customary unit for measuring length. One foot equals 304.8 mm; or 0.3048 meters. (ft.).

Feet per second
US customary unit for velocity. One foot per second equals 304.8 millimeters per second; or 0.3048 meters per second. (ft/s).

Field data logger
See data logger.

Filter
Granular material placed around a submarine pipe to facilitate drainage and at the same time strain or prevent the admission of silt or sediment.

Flexible
Readily bent or deformed without permanent damage.

Flight
The spiral plates surrounding the tube of an auger.

Flow
(1) Turns drilling fluid flow on. (2) Turns air on.

Flow control
A method whereby normal sewer flows or a portion of normal sewer flows are blocked, retarded, or diverted (bypassed) within certain areas of the sewer collection system.

Flow reduction
The process of decreasing flows into a collection system or of removing a proportion of the flow already in a collection system.

Force main
A pipeline that conveys sanitary combined or storm water flow under pressure from a pumping (or lift) station to a discharge point.

Fractures
Cracks visibly open along the length and/or circumference of the conduit with the pieces still in place.

Frame
A cast iron unit at the ground surface that provides entry into the manhole.

Frame ring
In a manhole, it is the metal frame which supports the cover.

Free boring
To bore or drill without the use of casing installed at the same time as the hole is cut. Not recommended for use with augers.

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Gallons per minute
US customary unit to measure liquid volume discharge rate. One gallon per minute equals 0.063 liters per second. (abbrev. GPM).

Grade
The elevations shown on plans and/or survey grade stakes for the installation of the carrier pipe. It is occasionally to give elevations for casing. In most cases, it is given to the flow line but can also be given to the top of the pipe or casing.

Granular
Technical term referring to (the uniform size on grains of crystals in rock.

Gravity sewer
A sewer that is designed to operate under open channel conditions (below pipe full capacity) up to a maximum design flow at which point it will become surcharged.

GRC
Glass fiber Reinforced Concrete; a rehabilitation lining.

Ground rod
This is a copper/brass rod which is hand driven into the ground and is connected to the drill rack and mats to provide adequate grounding of unit and personnel.

Ground rod cable
Cable connecting the mats and drill rig to the ground rod.

Ground water table (or level)
Upper surface of the zone of saturation in permeable rock or soil (when the upper surface is confined by impermeable rock, the water table is absent).

Groundwater table
See reference groundwater level.

Grout
(1) Material used to seal pipeline and manhole cracks; also used to seal connections within sewer structures. (2) A material, usually cement based, used to fill the annulus between the existing pipe and the lining; and also to fill voids.

Grouting
(1) Filling of the annular space between the Host pipe and the Carrier Pipe. Grouting is also used to fill the space around laterals and between the new pipe and manholes. Other uses of grouting are for localized repairs of defective pipes.

Guard
A protective device fitted to the machine to minimize the possibility of inadvertent contact with hazards.

Guidance system
The guidance system continuously confirms the position of the MBTM.

Guided auger boring
A term applied to auger boring systems which are similar to microtunneling, but with the guidance mechanism actuator sited in the drive Shaft (e.g. a hydraulic wrench which turns a steel casing with an asymmetric face at the cutting head).

Guided boring
Method for the installation of pipes, conduits and cables using a surface-launched drilling rig. A pilot bore is drilled using a rotating drill string and is then enlarged by a back reamer to the size required for the product pipe.

GWI
Groundwater Infiltration; results from the movement of groundwater in the saturated zone into the collection system through defects in the components of the system located below the water table.

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Hand excavation
The technique used to remove the material (rock, dirt, sand, etc.) by hand held tools (pick, shovel, etc.) from the tunnel face or open ditch.

HDPE
High Density Polyethylene, see polyethylene

Head (Static)
The height of water above any plane or point of references (The energy possessed by each unit of weight of a liquid, expressed as the vertical height through which a unit of weight would have to fall to release the average energy posed.)

Heaving
Process in which the ground in front of a pipe jack may be displaced forward and upward causing a lifting of the ground surface.

Height of Cover (HC)
Distance from crown of a culvert or conduit to the finished road surface, or ground surface, or the base of the rail.

High Density Polyethylene
A plastic resin made by the copolymerization of ethylene and a small amount of another hydrocarbon. The resulting base resin density, before additives or pigments, is greater than 0.941 gins/cc.

Hold down
A hinged or removable assembly that secures the boring machine to the track.

Horizontal directional drilling (HDD)
See directional drilling.

Horizontal earth boring
(Auger Boring, Boring & Jacking) The use of auger boring machines to prepare holes by the installation of a casing whereby the spoil is removed by the use of augers.

Horizontal earth boring machine
A machine used to bore horizontally through the earth by means of a rotating tool, or non-rotating pushing or piercing tool.

Hydraulic Cleaning
Techniques and methods used to clean sewer lines with water e.g.: water pumped in the form of a high velocity spray and water flowing by gravity or head pressure. Devices include high velocity jet cleaners, cleaning balls, and hinged disc cleaners.

Hydraulics
That branch of science or engineering which treats water or other fluid in motions.

Hydrocarbons, Gaseous
An organic compound made up of the elements of carbon and hydrogen that exists as a gas at ambient conditions.

Hydrocarbons, Liquid
An organic compound made up of the elements of carbon and hydrogen that exists as a liquid at ambient conditions.

Hydrogen Sulfide
An odorous gas sometimes found in sewer systems. Recognizable by a rotten egg odor. Chemical formula is H2S.

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Impact ramming
See pipe ramming.

Inert material
A material which is not very reactive, such as a noble metal or plastic.

Infiltration
(1) Penetration of freshwater or groundwater into the sewer system through cracks, defective joints in the pipeline, and holes, or through lateral connections, manholes or inspection chambers. (2) All extraneous waters (storm water and ground water).

Infiltration/Inflow (II)
The total quantity of water from both infiltration and inflow without distinguishing the source.

Inflow
Water discharged into a sewer system and service connections from sources on the surface.

Input parameter for electrical drive
Maximum continuous rated voltage and amperage.

Input parameter for hydraulic or pneumatic drive
Maximum continuous rated torque and shaft speed.

Input parameter for mechanical drive
Maximum continuous rated torque and shaft speed.

Inspector
The owner's on-site representative responsible for inspection and acceptance, approval, or rejection of work performed as set forth in these specifications.

Interceptor sewer
A sewer that conveys flow from a trunk sanitary sewer or dry weather flow plus a small volume of storm water from a trunk combined sewer to a wastewater treatment plant.

Interjack pipes
Pipes specially designed for use with an Intermediate Jacking Station.

Interjack station
See Intermediate Jacking Station.

Intermediate jacking method
Pipe jacking method to redistribute the jacking force by the use of intermediate jacking stations.

Intermediate Jacking Station
A fabricated steel cylinder fitted with hydraulic jacks that are incorporated into a pipeline between two pipe segments. Its function is to distribute the jacking load over the pipe string on long drives.

Internal corrosion
Corrosion that occurs inside a pipe because of the physical, chemical, or biological interactions between the pipe and the water as opposed to forces acting outside the pipe, such as soil, weather, or stress conditions.

Internal erosion
Abrasion and corrosion on the inside diameter of the pipe or tubing due to the fluid that is being transported.

Internal inspection
Means of ascertaining the condition of pipelines, either by visual inspection for man-entry size or by the use of remote control instrumentation.

Internal pipe inspection
The television inspection of a sewer line section. A CC-TV camera is moved through the line at a slow rate and a continuous picture is transmitted to an above ground monitor (see also PHYSICAL PIPE INSPECTION).

Invert
(1) The lowest point on the pipe circumference; also the defined channel in the manhole platform that directs flow from inlet pipe to outlet pipe. (2) The inside bottom, lowest elevation, of a sewer pipe.

Invert level (elevation)
The level (elevation) of the lowest portion of a liquid-carrying conduit, such as a sewer, which determines the hydraulic gradient available for moving the contained liquid.

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Jacking
The actual pushing of pipe or casing in an excavated hole. This is usually done with hydraulic cylinders (jacks), but has been done with mechanical jacks, air jacks and just about anything else that man could imagine.

Jacking force
Force applied to pipes in a pipe jacking operation.

Jacking frame
A structural component that houses the hydraulic cylinders used to propel the microtunneling machine and pipeline. The jacking frame serves to distribute the thrust load to the pipeline and the reaction load to the shaft wall or thrust wall.

Jacking pipes
Pipes designed to be installed using pipe jacking techniques.

Jacking pit
The excavation that the machinery is set into to install a casing or tunnel. (in years past, it has also been known as a Glory Hole).

Jacking shaft
Excavation from which trenchless technology equipment is launched for the installation or renovation of a pipeline, conduit or cable. May incorporate a thrust wall to spread reaction loads to the ground.

Jacking shield
A fabricated steel cylinder from within which the excavation is carried out either by hand or machine. Incorporated within the shield are facilities to allow it to be adjusted to control line and grade.

Jacking station (IJS)
See Immediate Jacking station.

Jet cutting (jetting)
(1) A type of Directional Drilling or Guided Boring technique using pressurized fluid jets to provide the soil cutting action. (2) A process using high pressure water to wash out the face of a utility crossing without any mechanical or hand excavation.

Joint sealing
Method in which an inflatable packer is inserted into a pipeline to span a leaking joint, resin or grout being injected until the joint is sealed and the packer then removed.

Joints
The means of connecting sectional lengths of sewer pipe into a continuous sewer line using various types of jointing materials. The number of joints depends on the lengths of the pipe sections used in the specific sewer construction work.

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Keepers
See hold down.

Kip
A stress unit equal to 1000 pounds.

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Lateral
A service line that transports wastewater from individual buildings to a main sewer line.

Lateral connection
The point at which the downstream end of a building drain or sewer connects into a larger diameter sewer.

Launch pit
Also known as Drive Pit, but more usually associated with "launching" an Impact Moling tool.

Launch seal
A mechanical seal, usually comprised of a rubber flange that is mounted to the wall of the drive shaft. The flange seal is distended by the MTBM as it passes through creating a seal to prevent water or lubrication inflow into the shaft during tunneling.

lb/ft
US customary units for weight per unit length. One lb/ft equals 1.488 kilograms per meter.

Line
(1) The specified direction of the proposed bore in a horizontal plane. (2) (Path) The shortest distance between two points as laid out by a survey crew for the installation of pipelines and their bores and tunnels.

Liner plate
A proprietary product, used to line tunnels instead of casing, and comes in formed steel segments. When these segments are bolted together they form a structural tube to protect the tunnel from collapsing. The segments are made so that they may be bolted together.

Lining
A rehabilitation process where a length of material is introduced to extend the life of the existing sewer. The lining may or may not utilize some structural strength from the existing sewer; and it may or may not function as a structural enhancement.

Live insertion
Installation of a liner whilst the product pipe remains in service.

Localized (spot) repair
Repair work on a pipe, particularly sewerage, to an extent less than the run between two access points.

Locator
An electronic instrument used to determine the position and strength of electro-magnetic signals emitted from a transmitter in the pilot head of a boring system, in an impact moling tool or from existing underground services.

Lubrication
A fluid, equal to 1000 pounds.

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Major blockage
A blockage (structural defect, collapse, protruding service connection, debris) which prohibits manhole-to-manhole cleaning, TV inspections pipe flow, or rehabilitation procedures.

Male hex connector
See shank.

Man-accessible
Description of a pipe or excavation which can be physically entered by an operative.

Man-entry
Describes any trenchless technology process which requires an operative to enter a pipe, duct or bore. OSHA has no minimum size limit for Man-Entry; however, they address a much broader concept of "confined space" in Title 29 Code of Federal Regulations.

Manhole
A structure that allows access to the sewer system.

Maximum allowable operating pressure
The highest working pressure expected and designed for during the service-life of the main.

Mechanical cleaning
Methods used to clean sewer lines of debris mechanically with devices such as rodding machines, bucket machines winch-pulled brushes, etc.

Microtunnel boring machine (MTBM)
The microtunnel boring machine (MBTM) refers to the microtunnel shield jacked through the earth which excavates the ground in advance of the pipe being installed.

Microtunneling
A trenchless construction method for installing pipelines. Microtunneling uses all of the following features are utilized during construction: (1) Remote controlled - The microtunneling boring machine (MTBM) is operated from a control panel.

Million gallons per day (mgd)
US customary unit for flow measurement. One MGD equals 43.81 liters per second.

Mixed face
A soil condition that presents two or more different types of material in the path of the bore.

Modifications
(1) A written amendment of the contract documents signed by both parties. (2) A change order. (c) A written clarification or interpretation issued by the engineer in accordance with the terms of the contract. (d) A written order for a minor change.

Muck
As a noun, it means the same as spoil. As a verb, it means to dig as in "muck out the hole."

Multistage new installation
To plan and undertake projects with regard to a phased/milestone schedule.

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Nominal size
Size of pipe or shaft used to define the internal working diameter.

Non-man entry
Size of pipe, duct or bore less than that for man-entry.

Notice of award
The written notice by owner to the apparent successful bidder stating that upon compliance with the conditions precedent to be fulfilled by him within the time specified, the owner will execute and deliver the agreement to him.

Notice to proceed
NTP, a written notice given by the owner to the contractor (with a copy to the engineer) fixing the date on which the contract time will commence to run and on which contractor shall start to perform his obligations under the contract documents.

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Obstruction
Any object or feature that lies completely or partially within the cross section of the microtunnel and prevents continued forward progress.

Open cut
The method by which access is gained to the required level underground for the installation, maintenance or inspection of a pipe, conduit or cable. The excavation is then backfilled and the surface restored. See conventional trenching.

Open face shield
Shield in which manual excavation is carried out from within a steel tube at the front of a pipe jack.

Organic debris
Production waste and other material that accumulates in sewers or manholes.

OSHA
Occupational Safety and Health Administration.

Outfall
An outlet to a sewer system.

Overcut
The annular space between the excavated hole and the outside diameter of the jacking pipe.

Overflow
(1) The excess water that flows over the ordinary limits of a sewer, manhole, or containment structure. (2) An outlet, pipe, or receptacle for the excess water.

Owner
A public body of authority, corporation as partnership, or individual for whom the work in to be performed.

Oxidation
Loss of electrons, as when a metal goes from the metallic state to the corroded state.

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Packer
See Compression ring.

PE
Polyethylene; a form of thermoplastic pipe.

Percent (%)
A dimensionless number with the ratio of one (1) to one hundred (100). In the construction industry, it is mostly used to give the rise or fall of a pipe line, or road, in feet per 100 feet.

Perched water table
In hydrology, the upper surface of a body of free ground water in a zone of saturation, separated by unsaturated material from an underlying body of ground water in a differing zone of saturation.

Permeability
Penetrability.

Physical pipe inspection
The crawling or walking through manually accessible pipe lines. The logs for physical pipe inspection record information of the kind detailed under TELEVISION INSPECTION. Manual inspection is only undertaken when field conditions permit this to be done.

Piling
Rigid supports, driven vertically to provide wall support in the pit.

Pilot bore
The action of creating the first (usually steerable) pass of any boring process which later requires back-reaming or similar enlarging. Most commonly applied to Guided Boring, Directional Drilling and 2-pass microtunneling systems.

Pilot Tube Method
A multi-stage method of accurately installing a product pipe by use of a guided pilot tube and followed by upsizing to install the product pipe.

Pipe
A long tube of clay, concrete, steel, metal, wood, etc., for conveying water, gas, oil or other materials.

Pipe bursting
A replacement method. A technique for breaking the existing pipe by brittle fracture, using force from within, applied mechanically, the remains being forced into the surrounding ground.

Pipe jacking
A system of directly installing pipes behind a shield machine by hydraulic jacking from a drive shaft such that the pipes form a continuous string in the ground.

Pipe lubricant
See Lubrication.

Pipe pulling
Method of replacing small diameter pipes where a new product pipe is attached to the existing pipe which is then pulled out of the ground.

Pipe pusher
A machine that pushes or pulls a rod or pipe to produce a bore by means of compaction without rotation or impact.

Pipe ramming
A non-steerable system of forming a bore by driving an open-ended steel casing using a percussive hammer from a Drive Pit. The soil may be removed from the casing by augering, jetting, or compressed air.

Pipe segment
A specific portion of the sewer system piping; usually runs between two structures (e.g., manhole, trap tanks, sumps); identified with unique sewer structure ID number.

Pipeline (also pipe)
Portions of the sewer system that are constructed of piping as opposed to manholes and other structures (e.g., trap tank, sumps, etc.).

Pipeline reconstruction
The repair of an existing pipeline that has suffered loss of pressure integrity or has been structurally damaged. The liner becomes the principal pressure containment or structural element of the composite pipe structure.

Pipeline rehabilitation
The repair of an existing pipeline, which has become corroded or abraded, by insert renewal of a liner which rehabilitates the bore of the pipeline but does not contribute significantly to increased pressure capability or increased structural capability.

Pipeline system
Interconnecting pipe network for the conveyance of fluids.

Planner
Individual who defines and schedules maintenance (including inspection) activities and provide coordination between operations and work groups.

Plastic
Any of a variety of thermoplastic and thermoset material used in sewer construction (e.g., high-density polyethylene, polypropylene, PVC, fiberglass reinforced plastics, polyester felt reinforced pipe, epoxy and polyester mortars, etc).

Plate
A flat-rolled iron or steel product.

Point source repair
See localized repair.

Polyethylene
A ductile, durable, virtually inert thermoplastic composed by polymers of ethylene. It is normally a translucent, tough solid. In pipe grade resins, ethylene-hexene copolymers are usually specified with carbon black pigment for weatherability.

Ponding
Jetting or the use of water to hasten the settlement of an embankment - requires the judgment of a soils engineer. In hydraulics, pending refers to water backed up in a channel or ditch as the result of a culvert of inadequate capacity or design.

Potholing
Digging of a hole to locate a utility.

Power package
The engine and drive section of a split boring machine or the remote engine and hydraulic pumps of a power unit.

Power requirements
Manufacturer’s recommend maximum flow and pressure.

Precipitation
Process by which water in liquid or solid state (rain, sleet, snow) is discharged out of the atmosphere upon a land or water surface.

Pressure
Changes the drilling fluid pressure.

Pressure rating
Estimated maximum internal pressure that allows a high degree of certainty that failure of the pipe will not occur.

Pressurized
To pump or force a liquid at a higher rate than that achievable under normal open channel or free surface conditions.

Preventative
Routine maintenance designed to prevent sewer system maintenance problems.

Primary pipe
The basic conduit when used in conjunction with a "protective liner"; when inspected and evaluated it is the basic or primary pipe which must meet the fit-for-use criteria.

Privatize
To take out of public operation or ownership; to instigate private sector participation in the financing and/or operation and/or maintenance and/or ownership of public assets, such as treatment plants and collection systems.

Product Pipe
Permanent pipeline for operational use. Pipe for conveyance for water, gas, sewage, and other products.

Profile
Anchor pattern on a surface produce by abrasive, blasting or acid treatment.

Project
The entire construction to be performed as provided in the contract documents.

Protruding
To be projecting outward.

PSI
Pounds per Square Inch. US customary unit for pressure. One PSI equals 6.896 Kilonewtons per square meter.

Pull back
That part of a guided boring or directional drilling operation in which the drill string is pulled back through the bore to the entry pit or surface rig, usually installing the product pipe at the same time.

Pull back force
The tensile load applied to a drill string during the pull back process. Guided boring and directional drilling rigs are generally rated by their maximum pull-back force.

Pull-in piping
Also referred to as insert renewal; installation procedure whereby pipe is pulled inside old mains and service lines to provide the new main or service line.

Push block
See thrust block.

Push package
See thrust package.

PVC
Polyvinyl Chloride; a form of thermoplastic Pipe.

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Rainfall
Precipitation in the form of water (usage includes snow).

Ramming
A percussive hammer is attached to an open end casing, which is driven through the ground. The spoil within the casing is removed to leave an open casing.

Receiving pit
(1) See exit pit. (2) An opening in the earth located at the expected exit of the cutting head or casing. (3) (Come out hole, Come out pit) The pit that is dug at the end of the bore, opposite the Jacking pit.

Receiving shaft
See Reception Shaft.

Reception shaft
Excavation into which the microtunneling equipment is driven and recovered.

Reception/exit shaft/pit
Excavation into which trenchless technology equipment is driven and recovered following the installation of the Product Pipe, conduit or cable.

Rehabilitation
(1) All methods for restoring or upgrading the performance of an existing pipeline system. (2) Methods by which the performance of a length of sewer is improved by incorporating the original sewer fabric, but excluding maintenance operations.

Reinforcement
The provision of an additional sewer which in conjunction with an existing sewer increases overall flow capacity.

Remote control system
The remote control system monitors and controls the MBTM, the automated transport system, and the guidance system from a location not in the MTBM.

Renewal
Construction of a new sewer, on or off the line of an existing sewer. The basic function and capacity of the new sewer being similar to the original.

Renovation
Methods of rehabilitation in which all or part of the original fabric of a pipeline are incorporated and its current performance improved.

Repair
Rectification of damage to the structural fabric of the sewer, or the reconstruction of short lengths, but not the reconstruction of a whole pipeline.

Replacement
Construction of a new sewer, on or off the line of an existing sewer. The function of the new sewer will incorporate that of the old, but may also include other improvements or development work.

Restoration
The backfilling, compaction and re-surfacing of any excavation in order to restore the surface and underlying structure to enable it to perform its original function.

Retract
The motion of the machine away from the face of the entrance pit.

Reverse
The counter-clockwise rotation of the auger as viewed from the machine end.

Rip rap
Rough stone of various sizes placed compactly or irregularly to prevent scour by water or debris.

Riser
A thin ring located between the frame and cone of a manhole. Used to bring the frame and cover final grade. Commonly, several risers are present in a manhole.

Rod pushing
Method of forming a pilot bore by driving a closed pipe head with rigid attachment from a launch pit into the soil which is displaced. Limited steering and monitoring capability may be provided, usually in conjunction with a locator. See thrust boring.

Rods
Either flexible poles, fiberglass or wood for example, for removing blockages in sewers; or graduated measuring devices for estimating internal sewer dimensions.

Roller cone bit or reamer
A bit or reamer in which the teeth rotate on separate, internal shafts that are usually aligned perpendicular to line. Used for boring rock.

Rotation controls
Those controls that control the direction and/or the rotation of the tool.

Rotation speed
The speed at which the rod turns.

RPM
Reinforced Plastic Mortar; a form of thermoset plastic pipe

Runoff
That part of precipitation carried off from the area upon which it falls. Also, the rate of surface discharge of the above. That part of precipitation reaching a stream, drain or sewer. Ratoride; a form of thermoplastic pipe.

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Safety factor
As used in determining re-inspection interval; a fractional multiplier, based on priority rating, to ensure sewer segment re-inspection prior to becoming not fit for use.

Safety glasses
Eye protection to be worn at all times.

Samples
Physical examples which illustrate materials, equipment or workmanship and establish standards by which the work will be judged.

Seal
A water-tight bond.

Sediment
Particles that settle on the pipe invert, causing a reduction in cross sectional area.

Sediment debris
Specifies the extent of the problem (defect) based on the judgment of the field crew.

Seepage
Water escaping through or emerging from the ground along rather extensive line or surface, as contrasted with a spring, the water of which emerges from a single spot.

Segmental concrete tunnel liner
Used the same way as Liner Plate except that they are tunnel liners made of concrete.

Segmental lining
The use of prefabricated segments in Man-Entry work to form a new lining within a defective pipe. The segments are usually sealed at the joints and the annulus is grouted. See lining with pipe segments.

Separate system
A system that uses sanitary sewers to convey the wastewater and storm water sewers to carry the storm water.

Serviceability of the piping system
Continued service life with a high degree of confidence that a failure will not occur during its long-term service.

Settlement
See Subsidence.

Sewage
Wastewater transported in a sewer.

Sewer
An underground pipe or conduit for transporting storm water and/or wastewater.

Sewer cleaning
The utilization of mechanical or hydraulic equipment to dislodge, transport, and remove debris from sewer lines.

Sewer Inspection
Computer database used to store information about the Information Center sewer system.

Sewer interceptor
A sewer which receives the flow from collector sewers and conveys the wastewaters to treatment facilities.

Sewer lateral
A building sewer (sometimes referred to as a sewer lateral or house lateral) is the pipeline between the County sanitary sewer line, which is usually located in the street, and the indoor plumbing. County sanitary sewer lines have a pipe inside diameter.

Sewer pipe
A length of conduit, manufactured from various materials and in various lengths, that when joined together can be used to transport wastewaters from the points of origin to a treatment facility. Types of pipe are: Acrylonitrile-butadiene-styrene (ABS).

Sewer structure
Any portion of the industrial sewer system including pipeline segments, trap tanks, sumps and other structures; each are assigned a unique number.

Shaft
A pit or wall sunk from the ground surface into a tunnel for the purpose of furnishing ventilation or access to the tunnel.

Sheet piling
See piling.

Sheeting
A wall of metal plates or wood planking to keep out water, soft or runny materials.

Shield
A steel cylinder at the face of a utility tunnel or casing, which may sometimes employ the use of a mechanical excavator and may be steerable, and provide hazard protection from the area covered.

Shield tunneling method
Method of excavation in the front of a tunnel or pipe jack using a shield.

Shop drawings
All drawings, diagrams, illustrations, brochures, schedules, and other data which are prepared by the contractor, a subcontractor, manufacturer supplier or distributor and which illustrate the equipment, materials or some portion of the work.

Shoring
See piling.

Site
Any location where work has been or will be done.

Site access
An adequately clear area of a size sufficient to accommodate personnel and equipment required at the location where work is to be performed, including roadway or surface sufficiently, unobstructed to permit conveyance of vehicles.

Skin friction
Resistance to thrust caused by soil pressure around the casing.

Sleeve pipe
A pipe installed as external protection to a product pipe.

Slide
Movement of a part of the earth under force of gravity.

Slipline
A rehabilitation technique covering the insertion of one pipe inside an existing pipe.

Sliplining
(1) General term used to describe methods of lining with continuous pipes and lining with discrete pipes. (2) Insertion of a new pipe by pulling or pushing it into the existing pipe and grouting the annular space.


Slurry
A fluid, normally water, used in a closed loop system for the removal of spoil and for the balance of groundwater pressure during microtunneling.

Slurry Chamber
Located behind the cutting head of a slurry microtunneling machine. Excavated material is mixed with slurry in the chamber for transport to the surface.

Slurry Line
A series of hoses or pipes that transport tunnel muck and slurry from the face of a slurry microtunneling machine to the ground surface for separation.

Slurry Separation
A process where excavated material is separated from the circulation slurry.

Slurry shield method
Method using a mechanical tunnelling shield with closed face which employs hydraulic means for removing the excavated material and balances the ground water pressure. See also Earth Pressure Balance Machine.


Social costs
Costs incurred by society as a result of collection system works. These include business losses due to road closures, and the cost of extended journey times due to traffic delays and diversions.

Sonde housing
This integral unit is the direction drill head which also houses the sonde radio sending unit.

Spacer block
Device used to extend the distance that the hydraulic rams within a jacking system can propel the pipeline.

Spacers
See Compression ring.

Spalling
(1) A process that describes the flaking, or slitting away of the surface layer. (2) The spontaneous chipping, fragmentation, or separation of a surface or surface coating.

Special Conditions
When included as a part of the contract documents. Special conditions refer only to the work under this contract.

Specifications
Those portions of the contract documents consisting of written technical descriptions of materials, equipment, construction systems, standards and workmanship as applied to the work.

Speed controls
Those controls that control the speed of the engine, rotation of the tool, travel of tool, and forward or lateral movement of the machine.

Speed reducer
See final drive.

Spillway
A low-level passage serving a dam or reservoir through which surplus water may be discharged; usually an open ditch around the end of a dam, a gateway, or a pipe in a dam. - An outlet pipe, flume or channel serving to discharge water from a ditch.

Spiral weld pipe (casing)
Pipe made from coils of steel plate by wrapping around a mandrail in such a manner that the welds are a spiral helix.

Spoil (muck)
Earth, rock and other materials displaced by a tunnel or casing, and removed as the tunnel or casing is installed. In some cases, it is used to mean only the material that has no further use.

Spoil ejector door
A door that partially or completely closes the spoil opening when at rest.

Spot repair
See localized repair.

Springline
(1) Also Springing. An imaginary horizontal line across the sewer that passes between the points where the sewer has its greatest cross sectional width. (2) Midpoint of sewer pipe. (The line equal distance between the crown and the invert of the pipe).

SSBS
Sanitary Sewer Bypasses; structures to relieve hydraulic overload on nominally sanitary sewers, leading to flooding and or pollution of a watercourse. Typically occurring during wet weather.

SSES
Sewer System Evaluation Survey; mainly for inflow and infiltration (I/I) surveys to determine the degree and location of flows entering the collection system.

Stabilization
See Chemical Stabilization.

Stabilizer
An ingredient used in the formulation of some plastics to assist in maintaining the physical and chemical properties of the materials at their initial values throughout the processing service life of the material.

Steering head
A moveable lead section of casing that can be adjusted to steer the bore.

Stoppage
A blockage in the sewer line that prevents the passage of wastewater.

Storm
A rainfall event. (See also - catastrophic rainfall event.)

Storm mains
Primary collector pipelines in the storm water collection system.

Storm sewer
A sewer intended to carry only storm waters, surface runoffs, street wash waters, and drainage.

Storm water sewer
A sewer that conveys storm water runoff from two or more properties and storm water runoff from roofs, paved areas and roads within the catchment area of the sewer.

Stress
The load applied per unit area of material. Often expressed as pounds of force per square inch (psi).

Stress relieve
The decrease in imposed stresses at a constant strain. In thermoplastic materials it occurs as a property of the material with time.

Structural
Physical adequacy to support imposed loads.

Structure ID
A number that defines a component of the sewer system.

Subcontractor
An individual, firm or corporation having a direct contract with contractor or with any other subcontractor for the performance of a part of the work at the site - or - An individual, firm or corporation having direct contract with the contractor.

Sub grade
The surface of a portion of the roadbed on which paving, or railroad track ballast, or other structure is placed.

Subsidence
The settlement of the ground, pipeline or other structure. The effects may not be evenly distributed and differential settlement may occur.

Sump
A depression in the pit to allow for the collection of water and the installation of a pump for water removal.

Supplier
Any person or organization who supplies materials or equipment for the work, inducing that fabricated to a special designs, but who does not perform labor at the site.

Surcharge
When the sewer flow exceeds the hydraulic carrying capacity of the sewer line.

Surcharged sewer
A gravity sewer that is overloaded beyond its pipe full flow capacity such that the flow becomes pressurized.

Surety
The corporate body which is bound with the contractor and which engages to be responsible for the contractor and his acceptable performance of the work.

Surface hardness
A measure of the net increase in depth as an indented load is increased from a minor load to a major load and then returned to a minor load. This is used as an indication of relative hardness among like materials.

Survey tools
Down hole equipment and instruments used to determine the position of a bore in directional drilling or in site investigation.

Swivel pulling
Used to attach service (to be pulled into drilled hole) to drill pipe.

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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.

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 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.

Torque
The rotary force available at the drive chuck.

Track
A set of longitudinal rails mounted on cross members that support and guide a boring machine.

Travel
Changes travel speed.

Trench box
A pre-constructed 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 storm water 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.

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)
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.

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 excavation.

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Uncased bore
Any bore without a lining or pipe inserted, i.e. self-supporting, whether temporary or permanent.

Underground utility
Active or inactive services or utilities below ground level.

Upsizing
Any method that increases the cross sectional area of an existing pipeline by replacing with a larger diameter pipe.

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Valve
Mechanism that controls the volume or direction of flow Can be closed, partially open, or fully open.

VCP
Vitrified Clay Pipe

Virgin soils
Soils which have not previously been excavated.

Voids
(1) Holes on the outside of the pipe in the surrounding soil or material. (2) A term generally applied to paints to describe holidays, holes, and skips in the film. Also used to describe shrinkage in castings or welds.

Volume
The amount of drilling fluid flow.

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Wall
Also riser. The vertical section between the bench and the cone of a manhole.

Wastewater
The liquid conveyed in sewer system.

Water jetting
Method for the internal cleansing of pipelines using high pressure water jets.

Water level
An instrument that uses a tube filled with water to indicate the elevation of the lead section of casing.

Water table
(1) The elevation of the ground water. (2) The upper limit of the portion of ground wholly saturated with water.

Waterline
Maximum liquid level in a sewer pipe/structure during normal operating cycles.

Winch
Mechanical device used to pull the CCTV cameras or cleaning tools through a sewer pipe.

Wing cutters
Appendages on cutting heads that will open to increase the cutting diameter of the head when turned in a forward direction, and close when turned in a reverse direction. They are used to cut clearance for the casing pipe.

Work
Any and all obligations, duties and responsibilities necessary to the successful completion of the project assigned to or undertaken by contractor under the contract documents, including all labor, materials, equipment and other incidentals.

Written Notice
The term "notice" as used herein shall mean and include all written notices, demands, instructions, claims, approvals, and disapproval required to obtain compliance with contract requirements. Written notice shall be deemed to have been duly served.

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Zones
Different areas in manholes and other structures which are used for defect evaluation.