C27 License - C-27 Landscaping Contractor License Irrigation Systems Installation Questions and Answers — Questions and Answers
Question 1: A client notices consistently dry spots in their lawn despite the irrigation system running regularly. The system has mixed types of sprinkler heads (e.g., full-circle, half-circle, and quarter-circle) within the same zone. What is the MOST likely cause of the uneven watering?
- The backflow preventer is malfunctioning.
- The system lacks matched precipitation rates (MPR). (Correct answer)
- The main water pressure to the property is too low.
- The controller is programmed for the wrong season.
Correct answer: The system lacks matched precipitation rates (MPR).
When sprinkler heads with different arcs (full, half, quarter) are on the same zone without adjustments, they apply water at different rates. Matched precipitation rate (MPR) nozzles ensure that all heads in a zone deliver a similar amount of water over a given area, regardless of their spray pattern, preventing wet and dry spots.
Question 2: According to California regulations, what is the minimum requirement for backflow prevention on a new irrigation system connected to a public water supply?
- An atmospheric vacuum breaker (AVB) on each valve.
- A double-check valve assembly (DCVA) at the point of connection.
- A reduced pressure principle (RP) backflow prevention assembly. (Correct answer)
- Annual inspection by a certified tester is sufficient.
Correct answer: A reduced pressure principle (RP) backflow prevention assembly.
California Code of Regulations, Title 17, requires the protection of public water systems from cross-connections. For irrigation systems, which are considered a high hazard, a reduced pressure principle (RP) backflow prevention assembly is typically required at the service connection to provide the highest level of protection against both back-siphonage and back-pressure.
Question 3: Which of the following factors is the PRIMARY determinant of friction loss in an irrigation pipe?
- The brand of the PVC pipe.
- The time of day the system operates.
- The elevation change of the landscape.
- The velocity and volume of water flow. (Correct answer)
Correct answer: The velocity and volume of water flow.
Friction loss is the pressure lost as water moves through a pipe due to friction against the pipe's inner walls. This loss is primarily determined by the velocity of the water (how fast it's moving) and the flow rate or volume (how much water is moving). Higher velocity and greater volume significantly increase friction loss.
Question 4: A landscape contractor is installing an irrigation system in a non-turf area on a slope greater than 25%. Which type of irrigation is required to maximize water infiltration and prevent runoff?
- Impact-drive rotary sprinklers.
- High-efficiency spray nozzles.
- Drip irrigation or other low-volume technology. (Correct answer)
- A hose-end sprinkler moved manually.
Correct answer: Drip irrigation or other low-volume technology.
On steep slopes, applying water slowly is crucial to allow it to soak into the soil rather than running off. Drip irrigation and other low-volume systems apply water directly to the root zone at a very low rate, which is ideal for preventing erosion and water waste on sloped areas.
Question 5: If an automatic irrigation valve fails to shut off after a watering cycle, what is the most common component to investigate first?
- A clogged sprinkler nozzle.
- The master valve.
- A faulty solenoid or debris in the valve diaphragm. (Correct answer)
- A tripped circuit breaker at the controller.
Correct answer: A faulty solenoid or debris in the valve diaphragm.
A valve that stays open is often due to a problem with its activation mechanism. This could be a malfunctioning electrical solenoid that isn't de-energizing or, more commonly, small debris like sand or a pebble lodged in the valve's diaphragm, preventing it from creating a proper seal to shut off the water flow.
Question 6: What is the primary purpose of 'hydrozoning' in irrigation system design?
- To group plants based on their mature height.
- To ensure all pipes used are the same diameter.
- To group plants with similar water requirements onto the same valve circuit. (Correct answer)
- To alternate watering days for different sections of the landscape.
Correct answer: To group plants with similar water requirements onto the same valve circuit.
Hydrozoning is a water-efficient design practice that involves grouping plants with similar water needs together in the landscape. This allows each irrigation zone (controlled by a single valve) to be programmed with a watering schedule that precisely meets the needs of those specific plants, preventing overwatering of some plants and underwatering of others.
C27 License - C-27 Landscaping Contractor License Irrigation Systems Installation Questions and Answers
A client notices consistently dry spots in their lawn despite the irrigation system running regularly.
The system has mixed types of sprinkler heads (e.g., full-circle, half-circle, and quarter-circle) within the same zone.
What is the MOST likely cause of the uneven watering?