Glossary of Construction and Engineering Terminology

HEB / N. West
Compiled by: Al Jonsson - 2001
Click Here for Streamkeepers Glossary
| Culverts | Open Channel Flow | Aggregates | Vegetation | River Hydrology |
| Pumps | Fish Passage | Surveying/mapping | Concrete | Activities |
| Equipment |


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 galvanised 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 apron that smoothes the hydraulic transition from open channel to culvert flow and increases maximum capacity. It may also be the mounting point for 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: 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.

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 grate 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.


Top of Page

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 disapait 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.


Top of Page


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 semi composted wood chips, leaves etc

Overburden: native soils overlying aggregate to be 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.


Top of Page


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

Calliper: 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


Top of Page

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 innundation.

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

Incise: downcutting of a channel, generally without a corresponding downcutting 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 stream 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.


Top of Page


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 inlet 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.


Top of Page

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 1.25x 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.


Top of Page


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 corners 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.


Top of Page


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 in the manufacture of 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.

Top of Page


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.

Top of Page


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: tracked vehicle with front mounted blade.

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

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: wheeled or tracked vehicle with wide front mounted bucket to scrape and load trucks.

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.