CSLB C-27 Landscaping ContractorSite Preparation and DrainageHard
A landscape contractor is tasked with installing a new irrigation main line in a residential backyard. The local municipality requires that all main lines be installed below the typical frost line to prevent freezing and damage. If the local frost line is 18 inches, what is the minimum acceptable depth for the top of the irrigation main line?
- A24 inches
- B18 inches
- C20 inches
- D12 inches
Show answer & explanationAnswer & explanation
Correct answer: C. 20 inches
To ensure the top of the main line is below the 18-inch frost line, a minimum depth of 20 inches would be required. This provides a buffer, placing the entire pipe safely below the potential freezing depth, accounting for variations and ensuring system integrity.
Why the other options are wrong
- A. 24 inches would also be acceptable as it is below the frost line, but 20 inches is the minimum that satisfies the requirement.
- B. 18 inches places the top of the pipe exactly at the frost line, which is insufficient as some part of the pipe could still freeze.
- D. 12 inches is above the frost line and would expose the pipe to freezing temperatures.
Irrigation Main Line Depth (Frost Line)
Irrigation main lines must be installed with the top of the pipe below the local frost line, plus a buffer, to prevent freezing and damage.
- Frost line depth varies by geographic location.
- Pipe must be entirely below the frost line.
- A minimum of 2 inches below the frost line is a common buffer.
- Prevents costly repairs due to burst pipes.
Memory trick: Below the frost, the pipe won't be lost!