CSLB C-27 Landscaping ContractorSite Preparation and DrainageHard
A C-27 contractor is designing a subsurface drainage system for a large, flat lawn area that experiences frequent waterlogging. The plan includes a network of perforated drain pipes. What is the generally recommended maximum spacing between these pipes to ensure effective drainage in most landscape applications?
- A30 feet
- B20 feet
- C10 feet
- D5 feet
Show answer & explanationAnswer & explanation
Correct answer: B. 20 feet
For effective subsurface drainage in a large, flat lawn area, a maximum spacing of 20 feet between perforated drain pipes is generally recommended. This spacing ensures that the entire area benefits from the drainage system, preventing waterlogging without over-engineering or excessive cost. Closer spacing might be needed for extremely heavy clay, but 20 feet is a common landscape standard.
Why the other options are wrong
- A. 30 feet spacing is generally too wide for effective subsurface drainage in areas prone to waterlogging, as the water may not reach the pipes efficiently.
- C. 10 feet spacing is common for moderately heavy soils or areas with persistent water issues, but 20 feet can still be effective in many cases.
- D. 5 feet spacing is typically used for very heavy clay soils or high-value sports fields where rapid drainage is paramount, often overkill for general landscape.
Subsurface Drain Pipe Spacing
The recommended maximum distance between parallel perforated drain pipes in a subsurface drainage system to effectively dewater an area.
- Varies based on soil type and drainage needs.
- Typically 10-20 feet for general landscapes.
- Closer spacing for heavier clay soils.
- Wider spacing for sandy or well-draining soils.
Memory trick: Twenty Feet, Trouble Flees, Turf Thrives.