Angle of Repose

The maximum angle of a stable slope of a granular material determined by friction, cohesion, and the shapes of the soil particles.

Backsight

The reading on a rod held at a point of known or assumed elevation.

Bench Mark (BM)

A relatively permanent object, natural or artificial, bearing a marked point whose elevation above or below the adopted datum is known or assumed.

Closure Error

The difference between a measured or calculated elevation and the true or established elevation.

Coarse Grained Soil

Soil in which 50 percent or more, by weight, of the soil is retained on the Number 200 sieve. In other words, 50 percent or more of the sample is composed of sand and/or gravel.

A land survey that provides points and elevations for building civil engineering projects. Often called engineering survey.

Control Survey

Survey that establishes a network of horizontal and vertical monuments that serve as a reference framework for other surveys.

Datum

Any surface to which elevations are referred (for example, mean sea level).

Design Storm

A selected storm event, described in terms of the probability of occurring once within a given number of years, for which drainage or flood control improvements are designed and built.

Detention Pond (Dry Pond)

A pond that collects storm water, temporarily stores, and then slowly releases the water into the municipal storm water system.

Differential Leveling

The process of determining the difference in height between a plane of sight and a point.

Duration

The period of time over which rain is measured. For example in the case of annual rainfall measurements, the duration is one year.

Egress

Exit or a way out.

Elevation

The vertical distance from a datum to a point or object.

Field Notes

A complete record of all measurements made during the survey with sketches and narration, where necessary, to clarify the notes.

Fine Grained Soil

Soil in which more than 50 percent, by weight, of the soil passes the Number 200 sieve. In other words, more than 50 percent of the soil is composed of silt and/or clay.

Finish Grade

The final elevation of the ground surface after excavating or filling.

Foresight

The reading on a rod held at a point whose elevation is to be determined.

Geodetic Survey

Surveys to determine relative positions of widely spaced points which require consideration of the size and shape of the Earth.

Grading

The process of changing the topography of a property for a purpose.

Height of Instrument

The vertical distance from the datum to the line of sight of the instrument.

Ingress

Entrance or means to enter.

Initial Point

The starting point for a survey.

Land Surveying

The science of determining relative positions of points on or near the Earth’s surface.

Liquid Limit

The minimum moisture content, expressed as a percentage of the oven dry soil weight, at which the soil will begin to flow when subjected to a small shearing force. The liquid limit is determined using a standard liquid limit device.

Low Impact Development

A storm water management approach that uses green space, native landscaping, and techniques that mimic a site’s pre-development water cycle.

Plane Survey

Surveys for which the curvature of the Earth is ignored and measurements are treated as if taken on a plane surface.

Plastic Limit

The minimum moisture content at which the soil can be rolled into a thread one-eighth of an inch in diameter without crumbling and is determined by trial and error.

Plasticity Index

The difference between the liquid limit and the plastic limit.

Poorly Graded

A soil that does not contain a good representation of all particle sizes. A poorly graded soil may contain a narrow range of particle sizes (uniformly graded) or may not contain one or more ranges of particle sizes (gap graded).

Property Survey

A land survey that establishes property corners, boundaries, and areas of land parcels. Also called land surveys, cadastral surveys, and boundary surveys.

Rainfall Intensity

The ratio of the total amount of rain (rainfall depth) falling during a given period to the duration of the period.

Retention Pond (Wet Pond)

A permanent on-site pond used to manage storm water in which pollutants are allowed to settle out or be removed by biological activity.

Return Period

The length of time, on average, over which an event (or an event of greater magnitude) is expected to occur not more than one time. For example, a Category 3 hurricane may have a return period of 100 years, which means that a Category 3 hurricane (or stronger) is expected to occur no more than one time, on average, within one hundred years.

Rod Intercept

The difference between the rod readings at the stadia wires.

Runoff Coefficient

A number that indicates the portion of rainwater that will be discharged by a particular surface.

Stadia

Two horizontal cross wires that are equidistant from the center crosshair in the sight.

Storm Water Wetlands

A permanent shallow pool of diverted rainwater that incorporates wetland plants. Pollutants are removed through settling and biological activity.

Topographic Survey

A land survey used to prepare maps showing location of natural and man-made features and elevations of points on the ground.

Well Graded

A soil that displays a good representation of all particle sizes. For instance, well-graded sand will contain a fairly even distribution of coarse, medium, and fine sand.