Glossary of Construction and Engineering Terminology (HEB / N. West AJ -2001)


The following guide is here to assist you with some of the common terms shared amongst the many stakeholders working in the watershed.


Apron: a smooth (generally concrete) surface that is placed between culvert and channel to improve capacity and reduce erosion.

Backwater: to place a culvert or use a weir such that there will always be some depth of water within the culvert.

Bedding: fine gravel or crushed rock placed around culverts to evenly distribute load.

Bottomless: a culvert consisting of an arch with an open bottom such that native streambed is exposed.

Box Culvert: culvert of rectangular cross section, commonly of precast concrete.

CMP: corrugated metal pipe, generally galvanized and/or tarred for corrosion resistance

Cut-off Wall: a collar (metal, concrete etc) placed around a culvert to prevent piping.

Depth of Cover: depth of fill placed atop a culvert.

Directional Drilling: drilling sideways under structures/roadways/streams etc to place pipes, utility lines without excavation. Generally limited to less than 30cm diameter.

Flap Gate: a passive "trap door" device placed on culvert outlets to prevent inflow. The hinge can be on the top or side of the culvert.

Inlet Limited: a condition in which the maximum flow capacity of a culvert is determined by the hydraulic conditions of the inlet. Small changes to the inside of the culvert or outlet structure will have no effect on maximum capacity.

Inlet Structure: An arrangement of wing walls and aprons that smoothes the hydraulic transition from open channel to culvert flow and increases maximum capacity. It may also be the mounting point tor a trash rack.

Invert: the bottom of the culvert.

Headwall: a wall built at top and sides of a culvert end to secure adjacent soil.

Multi-plate: a large culvert made up of segments bolted together on site.

Obvert: interior top of a culvert, equal to the invert plus the culvert diameter

Outlet Structure: An arrangement of apron, wing walls and sometimes energy absorption structure at the end of a culvert.

Pipe Jacking: a process by which a culvert is pushed horizontally through the ground to allow placement of a culvert without excavation.

Pipe Arch: a "squished" CMP culvert that has greater invert width.

Piping: water flowing along the outside of a culvert. This can lead to erosion and failure.

Roughness: of quantifying the degree of drag on flowing water by a surface. Most commonly expressed as a dimensionless Manning's number.

Slope: measurement of the change in elevation with distance.

Sluice Gate: a manually or automatically operated sliding or rotating panel to restrict flow into or out of a culvert.

Surcharge: a condition in which the water elevation at the upstream end of a culvert exceeds the culvert obvert.

Trash Rack: a metal gate placed at the upstream end of a culvert to prevent woody debris, rocks etc from entering the culvert

Wing Wall: a flaring vertical wall on either side of a culvert.

Open Channel Flow

Critical: the flow condition at which point the water velocity equals the wave speed.

Free Board: the vertical distance from water surface to top of channel, dike etc.

Hydraulic Jump: an abrupt transition from super to sub critical -also know as a standing wave. Often used to dissipate energy.

Laminar: flow condition with no waves, eddies etc. Rarely encountered in open channel flow.

Roughness: a way of quantifying the degree of drag on flowing water by a surface. Most commonly expressed as a dimensionless Manning's number.

Slope: measurement of the change in elevation with distance.

Turbulent: flow condition with waves, eddies etc.

Velocity Profile: variation in water velocity vertically and horizontally due to roughness effects.

Weir: structure that spans a channel and controls the local streambed elevation.


Alluvial: native aggregates deposited by water flow.

Boulder: pieces of rock larger than 200mm.

Clay: grains of rock less than 0.001mm.

Clear Crush: crushed and screened rock that contains no fines -very porous.

Cobble: pieces of rock between 60mm and 200mm.

D-X: size that X% of an aggregate sample is smaller than.

Filter Layer: cobble, gravel, etc., placed under riprap to prevent native fines from washing out through the riprap. Geotextile may be used to supplement or replace this layer.

Geo-textile: heavy weight fabric of generally synthetic material used to stabilize aggregates, soil etc. May be of woven or felted composition.

Glacial: aggregates deposited by or through glacial processes.

Gravel: crushed or alluvial rock of size between 2mm and 60mm.

Hog Fuel: crushed, shattered or shredded bark, wood etc.

Loc-Bloc: large precast concrete brick (2.5'x2.5'x5') placed to interlock with others.

Mulch: raw or composted wood chips, leaves etc.

Overburden: native soils overlying aggregate to he mined or subsoils to be constructed upon.

Overs: oversized rocks, boulders etc.

Pit Run: unscreened alluvial aggregates as extracted from a pit.

Porosity: the percentage of open spaces between pieces of gravel cobble etc.

Procter Test: a method to determine the maximum density that can be achieved through wetting and packing for a given aggregate.

Rip Rap: coarse angular rock, generally blasted or crushed. Also known as shot rock.

Road Base: a mixture of gravel, sand and fines that compacts well.

Sand: grains of rock between 0.06mm and 2mm.

Silt: grains of rock between 0.002mm and 0.06mm.

Topsoil: native or manufactured soil with 15-40% organic content.

Well Graded: coarse grained soil with an even distribution of sizes.


Ball & Burlap: packaging method for field grown trees - root balls are wrapped in burlap and bound with string, wire etc.

Caliper: diameter of nursery tree at the butt.

C/C: center to center ~ distance between plants.

Coir: coarse fiber derived from outer husks of coconuts.

Conifer: a tree or shrub (usually evergreen) with seed cones and resinous sap.

DBH: diameter breast high ~ tree trunk diameter at 4-5' off the ground.

Deciduous: tree or shrub that loses its foliage during the winter.

Dibble: rod-like tool used to plant live stakes, plugs etc.

Hydroseed: to spray a mixture of seed (generally grass), fibre and tackifyer (glue) for rapid planting and erosion control.

Fascine: a bundle of live branches (generally willow or cottonwood) placed perpendicular to a slope to form a stable edge.

Hay: cut and dried grass and legumes ~ often with seeds.

Invasive: plants that grow so aggressively that they will dominate an area -generally of imported origin.

Legume: a plant that hosts nitrogen fixing bacteria within its roots such as peas.

Live drain: a bundle of live branches buried within a slope to convey water down the slope and limit erosion

Live whip/stake/pole: dormant branches of a self-rooting woody species used to establish vegetation, stabilize slopes etc.

Pot Size: standard nursery stock sizes expressed in inches diameter or gallons volume.

Plug: small (2-6") plant grown in a multi-celled tray.

Shock: dehydration of plants and trees due to transplanting.

Shrub: small to medium plant of woody character generally with multiple stems.

Snag: standing dead tree.

Soil wrap: geotextile used to enclose topsoil as a means of slope stabilization.

Straw: coarse stalks (generally of grain) without seeds.

Tree: medium to large plant of woody character, generally with a single stem.

Wattle: low retaining wall of live whips/stakes placed on a slope to form a terrace and limit erosion.

Wildlife tree: tree that is topped/killed but much of the trunk left standing (man-made snag).

Wind throw: tree blowdown, often due to removal of adjacent trees.

River Hydrology

Aggrade: to increase channel elevation by sediment accumulation.

Bedload: coarse aggregates carried by flowing water (rolled or bounced, but not suspended).

Confluence: the meeting of two streams.

Debris torrent: a mixture of water, soil, vegetation etc that flows with great speed and force down a channel.

Degrade: to decrease channel elevation by sediment removal (erosion or extraction).

Floodplain: the region flanking a river channel that is subject to periodic inundation.

Headward erosion: localized channel degradation that progresses upstream. Often due to removal of bedload.

Incise: down cutting of a channel, generally without a corresponding down cutting of the floodplain.

Meander: the tendency of a channel to move laterally.

Overland flow: river flow outside of defined channel.

Point bar: accumulation of bedload on the inside of a curve.

Pool: a localized increase in water depth, generally formed by scour processes.

Sinuosity: ratio of total strean1 length to straight line distance.

Riffle: reach of river channel characterized by shallow medium velocity flow over cobble or small boulder.

Run: reach of river characterized by deep medium to high velocity flow.

Scour: localized erosion of substrate and banks by river flow.

Sediment budget: annual volume of sediment transported by a river.

Tail out: riffle at downstream end of pool.

Tributary: smaller stream that contributes to flow of larger stream.

Undercut: a portion of stream channel underneath an overhanging bank, log, rock etc.


Archimedes screw: type of pump that looks like an angled corkscrew.

Axial flow: type of pump that acts like an outboard motor in a casing.

Centrifugal: type of pump that "flings" water outwards and into an exit pipe.

Dynamic head: the total equivalent head drop due to the static head and all friction losses.

Discharge: volume of water pumped at a specific head.

Float switch: float that can be set to turn pump on or off at set water level.

Impeller: the rotational element that actually contacts and moves the water.

Forebay: the structure for a pump, often holds the trash rack.

Static head: vertical distance from inlet water elevation to discharge elevation.

Sump: deep water filled hole that the pump inlet is placed into. Constructed to increase water depth in order to reduce vortex formation and air entrainment.

Fish Passage

Denil: fishway that rectangular in cross section and has many backward facing vanes that cause water to flow black on itself and induce extreme turbulence.

Jump height: vertical distance between water surfaces of two pools.

Jump pool: the "take-off' pool at the base of a fall. Generally must be a minimum of 1.25 x as deep as the jump height for leaping salmonids.

Off set baffles: beams, logs, curbs etc placed on either side of a culvert, flume etc so as to create turbulent flow and ease fish passage.

Orifice: a fishway consisting of stepped pools connected by submerged holes.

Pool and weir: a fishway consisting of stepped pools connected by small falls.

Steep-pass: simplified design of Denil fishway.

Slot: a fishway consisting of stepped pools connected by vertical slots.


At grade: at the local ground elevation.

Bench mark: an elevation reference point.

Chainage: linear distance.

Contour: an imaginary line linking points of equal elevation.

Flag: a piece of survey ribbon.

Geodetic: an elevation correlated to international standard.

GPS: Global Positioning System ... a series of satellites and ground based hardware that allow precision location anywhere on the surface of the globe.

I/P: abbreviation -iron pin (normally used to mark comers of property lots).

Level: horizontal, or: an optical/mechanical device that allows determination of horizontal.

O/S: abbreviation -offset (generally used when a survey stake cannot be placed on the exact point of interest).

Rod: measurement stick used with a level or theodolite.

R/W: abbreviation - right of way.

Stake: wood stake used to mark point of interest.

Theodolite: survey instrument with vertical and horizontal degree gradations.

Traverse: survey circuit.

UTM: Universal Transverse Mercator - standard map projection.


Aggregate: sand, gravel etc mixed with cement to form concrete.

Batch plant: local facility for preparation and distribution of concrete.

Blow out: rupture of concrete forms.

Cast-in-place: construction of forms and filling with concrete at final location.

Cement: aka Portland Cement - a dry powder consisting of burned limestone, gypsum and other chemicals - used the concrete, mortar, grout etc.

Concrete: a mixture of Portland cement, aggregate and water to form a stiff slurry that will chemically react and harden.

Exposed Aggregate: decorative technique for driveways, walks etc that involves washing half set concrete so as to expose gravel aggregate.

Form: wood or metal structure that concrete is poured into.

Grout: a concrete mixture that is made with fine aggregate to achieve a smooth surface or easily pumped mixture.

Light weight: the addition of lightweight aggregates such as pumice.

Precast: concrete products cast at a site remote from the final installation.

Pump: to use a pump to transport wet concrete from truck to form; or in the case of grout, to fill voids by pressure.

Re-bar: ribbed steel bars of various sizes used to give concrete strength in tension.

Slump: the "sloppiness" of wet concrete, generally more slump equals less strength.

Strength: the resistance of a cured core of concrete to crushing ~ expressed in Mpa.

Tilt-up: a method of building construction whereby concrete walls are cast in horizontal forms on site and then tilted to the final vertical position.

Vibrate: to use a mechanical device to vibrate wet concrete within forms to cause it to flow more easily and flow around re-bar etc.


Bar scalping/skimming: to remove a thin layer (1-5') from the top of gravel bars.

Drainage maintenance: to remove sediments and vegetation from ditches/ canals etc in order to improve conveyance.

Dry /wet pit mining: to isolate gravel extraction to a confined hole in a bar. Wet/dry refers to whether it goes below the water table at the time of extraction.


Articulated rock truck: a four-wheel drive dump truck with heavy duty tapered box and pivoting connection between cab and box.

Backhoe: a rubber tired vehicle with loader bucket in front and small excavator bucket at back.

Blast mat: a large heavy mat made from rubber tires used to confine debris during rock blasting.

Bob-cat: trade name for a four wheeled skid steer loader.

Breaker: hydraulic jackhammer, often mounted on an excavator.

Bull dozer: with front mounted blade.

Excavator: generally tracked vehicle with rotating body and front mounted digging ann.

Low bed: Truck tractor and low semi-trailer used to transport large excavators, dozers etc.

Grader: rubber tired vehicle with blade mounted between front and rear axles.

Hiab: Flatbed truck with hydraulic crane for loading and unloading freight.

Loader: or tracked with wide front mounted bucket to serape and load.

Reach: distance that an excavator arm can extend.

Spider: specialized excavator with four legs that can negotiate steep slopes and rivers with minimal impact.

Stone slinger: conveyor belt equipped dump truck than can precision place or "throw" gravel.

Swamp pad: large wood pad used to distribute excavator weight in soft conditions.

Swing: the space required for an excavator to rotate.

Tandem: tandem axle (rear) dump truck.

Thumb: metal beam located opposite an excavator's bucket, used to grip rocks etc.

Tree spade: specialized truck mounted device used to dig and transport large trees.






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