CLA CLA Grading & Drainage

Question 1

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

Accepted Answer

2%

Answer

A minimum 2% slope is generally recommended for lawn areas to direct stormwater away from buildings.

Question 2

A spot elevation of 102.50 is shown at the top of a swale and 100.00 at the bottom over a 50-foot run. What is the slope percentage?

Accepted Answer

5%

Answer

Slope % = (rise/run) × 100 = (2.50/50) × 100 = 5%.

Question 3

Which type of inlet is typically used at the low point of a parking lot to collect surface runoff?

Accepted Answer

Catch basin

Answer

Catch basins are standard at low points in paved areas because they collect surface water and trap sediment below the outlet pipe.

Question 4

What grading technique uses a series of flat terraces separated by steep risers to manage slopes on hillsides?

Accepted Answer

Bench grading

Answer

Bench grading creates level planting terraces on steep slopes, reducing erosion and allowing access.

Question 5

On a grading plan, a dashed contour line typically indicates:

Accepted Answer

Proposed grade

Answer

Dashed contour lines represent proposed (finished) grade, while solid lines represent existing grade.

(CLA) Certified Landscape Architect Practice Test