Landscape Design Grading and Drainage

Question 1

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

Accepted Answer

2%

Answer

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

Question 2

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

Accepted Answer

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

Answer

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

Question 3

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

Accepted Answer

Catch basin

Answer

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

Question 4

What is a swale in landscape design?

Accepted Answer

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

Answer

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

Question 5

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

Accepted Answer

1–2%

Answer

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

Landscape Design Practice Test