CLA CLA Grading & Drainage 3

Question 1

What ADA requirement applies to cross-slopes of accessible pedestrian routes?

Accepted Answer

Maximum 1:50 (2%)

Answer

The ADA Standards require cross-slopes on accessible routes to be no steeper than 1:50 (2%) to prevent wheelchair tipping.

Question 2

Which instrument is traditionally used in the field to measure elevations and set grades during landscape construction?

Accepted Answer

Automatic level (builder's level)

Answer

An automatic level (builder's level) with a rod is the classic instrument for measuring elevation differences and setting finish grade.

Question 3

A site has an impervious cover of 80%. Under the Rational Method, what coefficient (C) value would be most appropriate for runoff calculation?

Accepted Answer

0.75

Answer

A C value of approximately 0.70–0.85 is typical for heavily paved commercial areas with 80% impervious cover.

Question 4

What grading element is used along the back of a curb to prevent water from flowing onto adjacent property?

Accepted Answer

Interceptor swale

Answer

An interceptor swale (or diversion swale) catches upslope runoff and redirects it before it reaches adjacent properties or structures.

Question 5

Which contour interval would be most appropriate for detailed grading design on a relatively flat site (0–5% slopes)?

Accepted Answer

1 foot

Answer

A 1-foot contour interval provides the detail needed to show subtle grade changes on flat terrain critical for drainage design.

(CLA) Certified Landscape Architect Practice Test