LARE Section 3 key terms

The maximum load a soil can support per unit area without failing or settling excessively. Footings, retaining walls, and paving bases are sized against it.

The working soil pressure a designer may use, equal to ultimate bearing capacity divided by a factor of safety. It governs footing width for walls, columns, and pavilions.

Uneven downward movement of a structure's supports, causing cracking, tilting, or ponding. Landscape structures such as walls, steps, and paving are especially vulnerable at transitions between soil types.

Soil with high shrink-swell potential that expands when wet and contracts when dry. It damages paving, foundations, and retaining walls unless moisture is controlled or soil is amended or over-excavated.

The relative proportions of sand, silt, and clay particles in a soil. Texture controls drainage, water-holding capacity, and workability, and is described by the soil textural triangle.

The arrangement of soil particles into aggregates or peds, creating pore space. Good granular structure improves infiltration, aeration, and root growth, while compaction destroys it.

Densification of soil by removing air voids through mechanical pressure. It is required under paving and footings but harmful in planting areas because it restricts roots, water, and air.

The speed at which water moves through soil, often measured in inches per hour. It determines whether a site can accept stormwater infiltration and how large a treatment practice must be.

The highest elevation groundwater reaches during the wettest part of the year. It constrains infiltration practices, footings, and planting selection, and is often estimated from soil mottling.

Shaping land so that grade lines follow consistent elevations, creating level terraces or swales across a slope. It slows runoff, reduces erosion, and defines usable outdoor spaces.

Earthmoving that removes soil from high areas (cut) and places it in low areas (fill) to reach a design grade. Balancing cut and fill on site reduces hauling cost and import or export of soil.

A drawing using spot elevations, contours, or both to show proposed surface drainage and elevations. It is the primary construction document for ensuring water flows away from buildings.

A point-specific ground elevation noted on a grading plan, often at building corners, walks, and inlets. Spot elevations supplement contours where precise control of drainage or transitions is needed.

A shallow, vegetated channel that conveys and infiltrates stormwater. A bioswale adds engineered soil and plants to slow flow and filter pollutants before discharge or infiltration.

The downward entry of water from the surface into soil. Designers use it to reduce runoff volume, but its feasibility depends on percolation rate, water table depth, and pollutant loading.

Temporary storage of runoff in basins, tanks, or on surfaces, released slowly at a controlled rate. It reduces peak flows and downstream flooding compared with immediate discharge.

Storage of runoff that does not discharge to a downstream system, instead infiltrating, evaporating, or being reused. Retention reduces both peak flow and total runoff volume.

A surface such as pavement, roof, or compacted ground that prevents water from entering the soil. Its area drives runoff volume and is a standard basis for stormwater regulation.

A dimensionless ratio of runoff to rainfall for a given surface, used in the rational method. Higher values indicate less infiltration, as with asphalt compared with lawn or woodland.

A line on a map connecting points of equal elevation. Spacing indicates slope steepness: closely spaced contours mean steep terrain, widely spaced contours mean gentle terrain.

The ratio between a drawing dimension and the corresponding real-world dimension. Correct use of graphic and verbal scales is essential for measuring distances and calculating quantities.

An orthographic projection looking straight down at a site or object. Plans show layout, dimensions, and horizontal relationships; they do not show vertical relief without contours or elevations.

A drawing cut through an object or site to show internal or vertical relationships. Sections communicate grade changes, wall construction, and planting soil profiles.

An enlarged drawing of a small portion of a project showing how components fit and are assembled. Details specify materials, fasteners, and dimensions not visible at plan scale.

Drawings and written specifications that define the work for bidding and building. They are legally binding and must be coordinated so plans and specifications do not conflict.

Written requirements describing materials, workmanship, and performance standards for a project. Specifications supplement drawings and govern quality where drawings cannot convey it.

The complete package of drawings and specifications issued to contractors for pricing. It should be coordinated and complete, since changes after bidding often increase cost.

A structure that holds back soil at a change in grade. Its design depends on soil lateral pressure, wall height, drainage, and surcharge loads; drainage is critical to prevent failure.

A small opening in a retaining wall or wall base that lets accumulated water drain out. Without drainage, hydrostatic pressure can overturn or crack the wall.

A continuous, unobstructed path meeting minimum width, slope, surface, and clearance requirements so people with disabilities can travel. It must connect site arrival points to usable spaces and building entrances.

The gradient measured along the direction of travel on a walk or ramp. It is distinct from cross slope and is limited by accessibility standards for routes and ramps.

The gradient measured perpendicular to the direction of travel, used to shed water from walks and paving. Excessive cross slope makes routes difficult or unsafe for wheelchair users.

The unobstructed horizontal distance available for travel between edges, walls, or objects. It is measured at the narrowest point and must remain free of encroachments.

A sloped surface connecting two elevations, subject to limits on slope, length, landings, and handrails when part of an accessible route. Ramps require more space than stairs but provide access.

A level platform at the top, bottom, or between segments of a ramp or stair. Landings provide rest, turning space, and door maneuvering clearance.

A detectable, truncated-dome surface placed where pedestrians transition to a hazard such as a street or platform edge. It warns people who are blind or have low vision.

A sloped transition between a sidewalk and a street crossing, with detectable warnings and a level landing. It must align with the crossing and fit within the walk width.

Designing environments usable by the widest range of people without adaptation or specialized design. It goes beyond minimum accessibility compliance to consider usability across the lifespan.