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

1%

Answer

5%

Answer

10%

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

The initial rough grading of a site

Answer

The grade of the subsoil before topsoil application

Answer

The slope ratio of a retaining wall

Question 3

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

Accepted Answer

Catch basin

Answer

French drain

Answer

Swale

Answer

Bioswale

Question 4

What is a swale in landscape design?

Accepted Answer

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

Answer

A type of retaining wall used on slopes

Answer

A deep trench filled with gravel for subsurface drainage

Answer

A raised planting bed for water-loving plants

Question 5

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

Accepted Answer

1–2%

Answer

0.5%

Answer

5%

Answer

8%

Question 6

What does 'positive drainage' mean in landscape grading?

Accepted Answer

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

Answer

Using pumps to move water uphill to an outlet

Answer

Installing pressurized underground pipe systems

Answer

Adding soil berms around the perimeter of a property

Question 7

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

Accepted Answer

The intended direction of surface water movement across the graded site

Answer

The direction of prevailing winds across the site

Answer

The location of underground drainage pipes

Answer

The orientation of irrigation heads