Basic Terminology
Backfilling ……………… Placement of excavated soil in the trench after blinding has been completed.
Bedding ………………….. The earth foundation of the trench together with the select material around and over the drain, including envelope and filter material where used.
Berm ………………………… Strip or area of land, usually level, between the spoil bank and the edge of a channel or ditch.
Blinding …………………… Placement of select soil around a drain to prevent damage or misalignment when the trench is backfilled and to allow water to flow freely to the drain.
Coefficient of roughness ……….. Factor expressing the frictional resistance to flow of a channel surface or a drain interior.
Connections …………….Fittings used to join two drain lines.
Continuous pipe …….. Extended length of pipe without perforations or unsealed joints.
Deflection …………………Decrease in vertical diameter of tubing, often influenced by loading.
Ditch ……………………….. Constructed open channel for conducting water. See Drain.
Diversion ……………….. Channel constructed across the slope for the purpose of intercepting surface runoff.
Drain ……………………….. Conduit below the ground surface for removal of surplus ground or surface water. See Ditch.
Drainage area …………. Area from which drainage water is collected and delivered to an outlet. Sometimes referred to as the watershed area for a particular drain.
Drainage coefficient ……The depth of water, in inches, to be removed from an area within 24 hours.
Drainage system ……… Collection of surface ditches or subsurface drains, together with structures and pumps used to collect and dispose of excess surface or subsurface water.
Field ditch …………………. A graded ditch generally crossable with field equipment for collecting excess water from a field.
Grade or gradeline ……..Degree of slope of a channel or natural ground.
Inspection well …………….Opening to surface in drain line to permit observation of flow conditions.
Interceptor line or drain…….Surface ditch or subsurface drain, or a combination of both, designed and installed to intercept flowing water. Also, a line used to intercept several lines to keep the number of crossings at highways and similar locations to a minimum (also called collector lines).
Junction ……………………….Point of intersection of two or more surface ditches or subsurface drains.
Lateral ditch ……………….. Principal channel or ditch that conducts drainage water from the field ditches to an outlet channel.
Lateral drain ……………. Secondary drain that collects excess water from a field.
Main drain ……………….. Principal drain that conducts drainage water from the lateral drains and submains to an outlet.
Outlet channel …………… Channel constructed primarily to carry water from manmade structures such as drain lines, surface ditches, diversions, and terraces.
Pipe ……………………………. A continuous length of non perforated conduit typically used to protect an outlet or to provide additional structural strength.
Pipe drop inlet …………… Type of surface water inlet, fabricated from pipe materials, which lowers surface water to a ditch bottom.
Pumping plant …………… One or more pumps, power units, and appurtenances for lifting drainage water from a collecting basin to a gravity outlet.
Slope …………………………… Degree of deviation of a surface from the horizontal, usually expressed percent or a ratio of horizontal to vertical (i.e., 4:1).
Slot ……………………………….Perforations in plastic tubing. Also, the opening in the ground created by the trench less plow as it lays the tubing.
Spoil bank …………………… Soil excavated from channel, ditch, or other site and placed along the excavation site.
Stretch ………………………… The increase in length of the tubing caused by tension forces during installation. It is expressed as a percent increase of the length prior to installation.
Submain ……………………… Branch drain off the main drain which collects discharge water from laterals or from the field.
Tile ………………………………. Drains made of burned clay, concrete, or similar material, in short lengths, usually laid with open joints to collect and carry excess water from the soil.
Tubing …………………………. A flexible drain that gains part of its vertical soil load-carrying capacity by lateral support from the surrounding soil.
Watershed ……………………. Total land area above a given point on a stream or waterway that contributes runoff to that point.
Useful Conversion Factors
To convert Into Multiply by
acres hectares 0.405
acres square feet 43,560
acres square meters 4,047
acres square yards 4,840
centimeters feet 0.0328
centimeters inches 0.394
centimeters meters 0.01
centimeters yards 0.0109
cubic feet cubic inches 1,728
cubic feet cubic meters 0.0283
cubic feet gallons 7.48
cubic feet liters 28.3
cubic inches cubic feet 0.00058
cubic inches gallons 0.0043
cubic inches liters 0.0164
cubic meters cubic feet 35.3
cubic meters cubic inches 61,023
cubic meters gallons 264.2
cubic meters liters 1,000
feet centimeters 30.48
feet inches 12
feet meters 0.305
feet yards 0.333
gallons cubic feet 0.134
gallons cubic inches 231
gallons cubic meters 0.0038
gallons liters 3.79
hectares Acres 2.47
hectares square feet 107,600
hectares square meters 10,000
hectares square yards 11,956
inches centimeters 2.54
inches feet 0.083
inches yards 0.0278
kilometers feet 3,281
kilometers meters 1,000
kilometers miles 0.62
kilometers yards 1,094
To convert Into Multiply by
Liters cubic feet 0.0353
liters cubic inches 61.02
liters cubic meters 0.001
liters gallons 0.264
meters centimeters 100
meters feet 3.281
meters inches 39.37
meters kilometers 0.001
meters yards 1.094
miles feet 5,280
miles kilometers 1.61
miles meters 1,609
miles yards 1,760
square centimeters square inches 0.155
square centimeters square meters 0.0001
square feet square inches 144
square feet square meters 0.0929
square feet square yards 0.1111
square inches square centimeters 6.45
square inches square feet 0.007
square inches square meters 0.00064
square meters hectares 0.0001
square meters square centimeters 10,000
square meters square feet 10.76
square meters square inches 1,550
square meters square yards 1.2
square yards square feet 9
square yards square inches 1,296
square yards square meters 0.8361
yards centimeters 91.44
yards feet 3
yards inches 36
yards meters 0.914