(A) For the efficient use of water, an irrigation system design plan may be submitted for any project, but is not limited to meeting the requirements listed in this section and the manufacturer’s recommendations. The irrigation system and its related components shall be planned and designed to allow for proper installation, management, and maintenance.
(1) System.
(a) Dedicated landscape water meters are highly recommended on landscape areas smaller than 5,000 square feet to facilitate water management.
(b) Automatic irrigation controllers utilizing either evapotranspiration or soil moisture sensor data shall be required for irrigation scheduling in all irrigation systems.
(c) The irrigation system shall be designed to ensure that the dynamic pressure at each emission device is within the manufacturer’s recommended pressure range for optimal performance.
1. If the static pressure is above or below the required dynamic pressure of the irrigation system, pressure-regulating devices such as inline pressure regulators, booster pumps, or other devices shall be installed to meet the required dynamic pressure of the irrigation system.
2. Static water pressure, dynamic or operating pressure, and flow reading of the water supply shall be measured at the point of connection. These pressure and flow measurements shall be conducted at the design stage. If the measurements are not available at the design stage, the measurements shall be conducted at installation.
(d) Sensors (rain, freeze, wind, and the like), either integral or auxiliary, that suspend or alter irrigation operation during unfavorable weather conditions, shall be required on all irrigation systems, as appropriate for local climatic conditions. Irrigation should be avoided during windy or freezing weather or during rain.
(e) Manual shut-off valves (such as a gate valve, ball valve, or butterfly valve) shall be required, as close as possible to the point of connection of the water supply, to minimize water loss in case of an emergency (such as a main line break) or routine repair.
(f) Backflow prevention devices shall be required to protect the water supply from contamination by the irrigation system. A project applicant shall refer to the applicable local agency code (i.e., public health) for additional backflow prevention requirements.
(g) High flow sensors that detect and report high flow conditions created by system damage or malfunction are recommended.
(h) The irrigation system shall be analyzed to prevent runoff, low head drainage, overspray, or other similar conditions where irrigation water flows onto non-landscaped areas, such as adjacent property, non-irrigated areas, hardscapes, roadways, or structures.
(i) Relevant information from the soil management plan, such as soil type and infiltration rate, shall be utilized when designing irrigation systems.
(j) The design of the irrigation system shall be analyzed with the hydrozones of the landscape design plan.
(k) The irrigation system shall be analyzed with the the irrigation efficiency criteria as described in § 27.3-4 regarding the maximum applied water allowance.
(l) It is highly recommended that the project applicant or local agency inquire with the local water purveyor about peak water operating demands (on the water supply system) or water restrictions that may impact the effectiveness of the irrigation system.
(m) In mulched planting areas, the use of low volume irrigation is required to maximize water infiltration into the root zone.
(n) Sprinkler heads and other emission devices shall have matched precipitation rates, unless otherwise directed by the manufacturer’s recommendations.
(o) Head to head coverage is recommended. However, sprinkler spacing shall be designed to achieve the highest possible distribution uniformity using the manufacturer’s recommendations.
(p) Swing joints or other riser-protection components are required on all risers subject to damage that are adjacent to high traffic areas.
(q) Check valves or anti-drain valves are required for all irrigation systems.
(r) Narrow or irregularly shaped areas, including turf, less than eight feet in width in any direction shall be irrigated with subsurface irrigation or low volume irrigation system.
(s) Overhead irrigation shall be analyzed with any and all adjacent non-permeable surface. Allowable irrigation within the setback from non-permeable surfaces may include drip, drip line, or spray technology. The setback area may be planted or unplanted. The surfacing of the setback may be mulch, gravel, or other porous material. These restrictions may be modified if:
1. The landscape area is adjacent to permeable surfacing and no runoff occurs;
2. The adjacent non-permeable surfaces are designed and constructed to drain entirely to landscaping; or
3. The irrigation designer specifies an alternative design or technology, as part of the Landscape Documentation Package and clearly demonstrates strict adherence to irrigation system design criteria in § 27.3-7. Prevention of overspray and runoff must be confirmed during the irrigation audit.
(t) Slopes greater than 25% shall not be irrigated with an irrigation system with a precipitation rate exceeding 0.75 inches per hour. This restriction may be modified if the landscape designer specifies an alternative design or technology, as part of the Landscape Documentation Package, and clearly demonstrates no runoff or erosion will occur. Prevention of runoff and erosion must be confirmed during the irrigation audit.
(2) Hydrozone.
(a) Each valve shall be analyzed so as to irrigate a hydrozone with similar site, slope, sun exposure, soil conditions, and plant materials with similar water use.
(b) Sprinkler heads and other emission devices shall be selected based on what is appropriate for the plant type within that hydrozone.
(c) Where feasible, trees should be placed on separate valves from shrubs, groundcovers, and turf.
(d) Individual hydrozones that mix plants of moderate and low water use, or moderate and high water use, may be allowed if:
1. Plant factor calculation is based on the proportions of the respective plant water uses and their plant factor; or
2. The plant factor of the higher water using plant is used for calculations.
(e) Individual hydrozones that mix high and low water use plants shall not be permitted.
(f) On the landscape design plan and irrigation design plan, hydrozone areas shall be designated by number, letter, or other designation. On the irrigation design plan, designate the areas irrigated by each valve, and assign a number to each valve. Use this valve number in the Hydrozone Information Table. This table can also assist with the irrigation audit and programming the controller.
(B) The irrigation design plan may contain, without limitation, the following:
(1) Location and size of separate water meters for landscape;
(2) Location, type and size of all components of the irrigation system, including controllers, main and lateral lines, valves, sprinkler heads, moisture sensing devices, rain switches, quick couplers, pressure regulators, and backflow prevention devices;
(3) Static water pressure at the point of connection to the public water supply;
(4) Flow rate (gallons per minute), application rate (inches per hour), and design operating pressure (pressure per square inch) for each station;
(5) Recycled water irrigation systems as specified in § 27.3-14;
(6) The following statement: “I have complied with the criteria of the ordinance and applied them accordingly for the efficient use of water in the irrigation design plan”; and
(7) The signature of a licensed landscape architect, certified irrigation designer, licensed landscape contractor, or any other person authorized to design an irrigation system. (See §§ 5500.1, 5615, 5641, 5641.1, 5641.2, 5641.3, 5641.4, 5641.5, 5641.6, 6701, 7027.5 of the California Business and Professions Code, § 832.27 of Title 16 of the California Code of Regulations, and § 6721 of the California Food and Agricultural Code.)
(Ord. 1005, passed 8-3-2010)