Landscaping (C-27) · Lesson 3 of 7

Irrigation Design Checks: Setbacks, Narrow Strips, Slopes, and Meters

"Irrigation Design Checks: Setbacks, Narrow Strips, Slopes, and Meters" is lesson 3 of 7 in the Landscaping (C-27) Learning Hub. It opens with "The Irrigation Design Plan Carries Rules, Not Just Pipe" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. The Irrigation Design Plan Carries Rules, Not Just Pipe
  2. Setbacks and Narrow Areas
  3. Slopes: Rise Divided by Run
  4. Required Hardware: Meter, Controller, Sensors, Valves
  5. Program the Controller Inside the Watering Window

The worked example in the course applies this lesson to a realistic job in 5 steps.

What you'll be able to do

  • Explain the main idea of "Irrigation Design Checks: Setbacks, Narrow Strips, Slopes, and Meters" in plain language you can use on the exam.
  • Apply this step with confidence: "Slopes: Rise Divided by Run".
  • Apply this step with confidence: "Required Hardware: Meter, Controller, Sensors, Valves".
  • Apply this step with confidence: "Program the Controller Inside the Watering Window".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Irrigation Design Checks (MWELO Sec. 492.7)PLAN: BED ALONG 60 FT OF SIDEWALK (not to scale)SIDEWALK (non-permeable)24 in. setback: drip onlyoverhead spray zone (beyond 24 in.)60 ft x 2 ft = 120 sq ft drip-only strip24 in. = 2 ftSLOPE CHECK: BACK BANKrun = 20 ftrise = 6 ft6 / 20 x 100 = 30%THE FIVE CHECKS1 Overhead near pavementNone within 24 in. of a non-permeable surface(492.7(a)(1)(U))2 Narrow stripsUnder 10 ft wide: subsurface or no-overspray(492.7(a)(1)(T))3 Slope over 25%Max 0.75 in./hr; no turf at toe by hardscape(492.7(a)(1)(V), 492.6(a)(1)(D))4 Meter + flow sensorResidential irrigated area 5,000 sq ft or more(492.7(a)(1)(A), (G))5 Watering windowOverhead 8:00 p.m. to 10:00 a.m. = 14 hr(492.10(a)(2))6,200 sq ft: meter + flow sensor. Bank = 30% (over 25%): 0.75 in./hr cap.7 stations x 25 min = 2 h 55 min: fits the 14-hour window.Source: MWELO (23 CCR Div. 2, Ch. 2.7) Sec. 492.6(a)(1)(D), 492.7(a)(1), 492.10(a)(2).CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: The Irrigation Design Plan Carries Rules, Not Just Pipe

MWELO Sec. 492.7 applies to areas that need permanent irrigation (not areas irrigated only during plant establishment). The plan must show the meter, every component, the static pressure at the point of connection, and the flow rate (gpm), application rate (in./hr) and design pressure (psi) for each station, with a signed statement of compliance from a licensed landscape architect, certified irrigation designer, licensed landscape contractor or other person authorized to design irrigation (Sec. 492.7(b)). A C-27 contractor is on that list, so these checks are yours.

Step 2: Setbacks and Narrow Areas

Overhead irrigation is not permitted within 24 inches of any non-permeable surface; drip, drip line or other low-flow non-spray technology may be used in that setback, which may be planted or unplanted and surfaced with mulch, gravel or other porous material (Sec. 492.7(a)(1)(U)). Areas less than 10 feet wide in any direction must be irrigated with subsurface irrigation or other means that produces no runoff or overspray (Sec. 492.7(a)(1)(T)). The whole system must be designed to prevent runoff, low-head drainage and overspray onto adjacent property, hardscape, roadways or structures (Sec. 492.7(a)(1)(I)).

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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