terrain + construction quiz 1

vocab

Contour Line

An imaginary line on a plan connecting all points of equal elevation. Contours never cross, split, or touch (except at vertical surfaces like cliffs or walls), and they always close on themselves.

Contour Interval

The vertical distance in elevation between two adjacent contour lines. Common intervals in site work are $1\,\text{ft}$ or $2\,\text{ft}$, while smaller intervals ($0.5\,\text{ft}$ or less) are used for tight, detailed grading.

Index Contour

A heavier or bolder contour line, typically every 5th line, labeled with its elevation to help the reader orient quickly without counting every line.

Intermediate Contour

The lighter-weight contour lines between index contours. They represent the same interval but are not labeled, relying on the index contour for reference.

Spot Elevation

A single labeled point giving the exact elevation at a specific location, used at high points, low points, doorways, walk intersections, and other locations too precise to leave to contour interpretation alone.

Existing (Natural) Grade

The elevation and shape of the ground surface before any construction or grading work begins, shown with dashed contour lines.

Proposed (Finish) Grade

The elevation and shape of the ground surface after grading is complete, shown with solid contour lines.

Top of Curb (TOC)

The spot elevation at the top edge of a curb, used to establish the grade relationship between paving, curb, and adjacent surfaces.

Bottom of Curb (BOC)

The spot elevation at the base of a curb, typically at the gutter or pavement surface it meets. The difference between TOC and BOC equals the curb's exposed height (commonly $6\,\text{in.}$).

Top of Wall (TOW)

The spot elevation at the top of a retaining or freestanding wall, marking the finished grade or cap elevation on the high side.

Bottom of Wall (BOW)

The spot elevation at the base of a retaining wall, marking the finished grade at the wall's footing or low side. The difference between TOW and BOW indicates the exposed wall height.

Finished Floor Elevation (FFE)

The elevation of the top of a building's finished floor surface, used as the key reference point for grading around a structure to ensure proper drainage and freeboard.

Breakline

A line on a grading plan marking an abrupt change in slope direction or rate — such as the top or bottom of a slope, a ridge, or a swale — where the surface is not a smooth continuous grade.

Ridge

An elongated landform higher than surrounding terrain on two opposing sides. Indicated by contours forming a V or U shape that points downhill, away from high ground.

Knoll

A small, rounded hill — a compact, low-relief version of a hill, generally without the sharp topographic prominence associated with true summits.

Mound

A constructed or natural rounded rise, generally freestanding rather than connected to a ridge system, represented by concentric closed contour loops increasing in elevation toward the center.

Berm

A constructed linear mound of earth, typically used for screening, directing drainage, defining edges, or separating uses, distinguished from a mound by its elongated, linear form.

Plateau

A broad, relatively flat elevated area with at least one steep side dropping to lower terrain.

Promontory

A prominent point of high ground that projects out from the surrounding landform, often overlooking lower ground on three sides.

Terrace

A relatively flat, level area created by cutting and/or filling a sloped site into a stepped series of platforms, usually retained by walls or sloped banks between levels.

Depression

A low area surrounded by higher ground on all sides with no natural outlet, represented by closed contour loops decreasing in elevation toward the center.

Swale

A shallow, elongated depression designed to convey stormwater runoff along a low path, indicated by contours forming a V or U shape pointing uphill into high ground.

Valley

A larger, often naturally occurring elongated low area between two ridges or areas of higher ground, generally carrying a watercourse or drainage path.

Saddle

A low point along a ridge line, situated between two areas of higher ground on either side where two ridges and two valleys meet at a shared low point.

Basin

A broad depression, natural or constructed, often designed to collect and hold or slowly release stormwater.

Ditch

A utilitarian, steeper-sided excavated channel, often unlined or lined for higher-volume conveyance, contrasted with a shallow, gently sloped swale.

Slope

The steepness of a surface, expressed as a ratio (e.g., $3:1$, meaning $3\,\text{ft}$ horizontal for every $1\,\text{ft}$ vertical) or as a percentage ($\text{rise} \div \text{run} \times 100$).

Grade

Used as a noun for the elevation or slope of the ground surface, and as a verb for the act of shaping the ground surface through cutting and filling.

Cut

Excavation of existing material to lower the ground surface to the proposed grade.

Fill

Placement of material to raise the ground surface to the proposed grade.

Cut/Fill Balance

A grading design goal where the volume of material cut from the site approximately equals the volume needed for fill, minimizing the need to import or export soil.

Positive Drainage

Grading designed to ensure water moves away from a structure or area at a sufficient slope (commonly a $2\%$ minimum near buildings) to prevent ponding.

High Point (HP)

A labeled spot elevation marking a local peak in the grading plan, from which water drains away in multiple directions.

Low Point (LP)

A labeled spot elevation marking a local low point in the grading plan, toward which water drains.

Drainage Divide (Watershed Divide)

An imaginary line along a ridge that separates areas draining to different watersheds or drainage systems.