Grading and Drainage Flashcards

What is the minimum recommended slope for lawn areas to ensure proper drainage away from structures?

Answer: 2%

A 2% minimum slope (approximately 1/4 inch per foot) is the industry standard for directing surface water away from buildings.

What does 'finish grade' refer to in landscape design?

Answer: The final elevation of the soil surface after all grading work is complete

Finish grade is the final elevation of the ground surface after all grading, soil amendments, and topsoil placement are complete.

Which drainage structure collects surface water through a grated inlet and directs it into underground pipes?

Answer: Catch basin

A catch basin is a below-grade structure with a grated surface inlet that intercepts runoff and channels it into an underground pipe system.

What is a swale in landscape design?

Answer: A shallow, vegetated channel designed to convey and filter stormwater runoff

A swale is a shallow, broad channel that conveys stormwater runoff while allowing infiltration and filtration through vegetation and soil.

What percentage of slope is typically required for a paved patio surface to drain effectively?

Answer: 1–2%

Paved surfaces like patios require a 1–2% slope to drain water effectively while remaining comfortable and safe for users.

What does 'positive drainage' mean in landscape grading?

Answer: Grading the land so water flows away from structures toward appropriate collection points

Positive drainage means the site is graded so all surface water naturally flows away from buildings and toward designated drainage outlets, preventing water intrusion.

In a grading plan, what do drainage flow arrows indicate?

Answer: The intended direction of surface water movement across the graded site

Drainage flow arrows on a grading plan show the intended direction surface water will travel across the finished grade toward collection points or outlets.

What is a French drain?

Answer: A gravel-filled trench containing a perforated pipe that redirects groundwater away from an area

A French drain is a subsurface drainage solution consisting of a gravel-filled trench with a perforated pipe that collects and redirects groundwater away from problem areas.

What is the primary purpose of a retaining wall in landscape grading?

Answer: To hold back soil and resist lateral earth pressure on graded or terraced slopes

Retaining walls are structural elements engineered to hold back soil and resist lateral earth pressure when significant changes in grade must be maintained.

What term describes water that flows across the soil surface rather than infiltrating into the ground?

Answer: Runoff

Runoff is water that flows over the ground surface when precipitation exceeds the soil's infiltration capacity or when the surface is impervious.

What does 'daylighting' a drain mean in landscape design?

Answer: Extending a drainage pipe until it opens to the surface at a lower elevation

Daylighting refers to extending an underground drainage pipe to the surface at a lower point so water can exit the system by gravity into a vegetated area or waterway.

What is the primary function of a dry well in a landscape drainage system?

Answer: To provide a subsurface reservoir that allows collected water to slowly percolate into surrounding soil

A dry well is an underground structure designed to temporarily hold stormwater and allow it to gradually infiltrate into the surrounding native soil.

Which instrument is most commonly used to establish and verify grades on a landscape site?

Answer: Transit level or laser level

A transit level or laser level projects a horizontal reference plane across a site, allowing accurate measurement and verification of grade elevations.

What does 'cut and fill' mean in landscape grading operations?

Answer: Excavating soil from high areas and relocating it to fill low areas to achieve the desired grade

Cut and fill is a grading technique where soil excavated from elevated areas (cut) is moved and compacted into lower areas (fill) to achieve the target finished elevation.

What is a berm in landscape design?

Answer: A mound of soil built up above the surrounding grade

A berm is a compacted mound of soil raised above the surrounding grade, used to redirect drainage, provide visual screening, or add topographic interest.

What is the minimum recommended slope for surface drainage in planted landscape areas?

Answer: 1%

A minimum 1% slope is recommended for planted areas to ensure water moves away from structures and does not pool around plant root zones.

What is a culvert used for in landscape drainage?

Answer: A pipe or structure that allows water to flow under a road, path, or other obstruction

A culvert is a conduit that allows a drainage channel or stream to continue flowing beneath a road, pathway, or embankment without interruption.

What is a 'spot elevation' on a grading plan?

Answer: A specific point on the plan showing the exact finished elevation at that location

A spot elevation is a numerical label placed at a specific point on a grading plan indicating the exact finished ground elevation at that location.

What is a bioswale?

Answer: A vegetated channel that slows, filters, and infiltrates stormwater using plants and engineered soils

A bioswale is a stormwater management feature that uses vegetation, compost, and porous soils to slow runoff velocity, filter pollutants, and promote groundwater recharge.

Which information is typically shown on a grading plan?

Answer: Existing and proposed contour lines, spot elevations, drainage flow arrows, and slopes

A grading plan shows existing and proposed contour lines, spot elevations, drainage flow arrows, percent slopes, and key drainage structures to document how a site will be shaped.