(A) Irrigation system requirements. This section applies to landscaped areas requiring permanent irrigation, not areas that require temporary irrigation solely for the plant establishment period. For the efficient use of water, an irrigation system shall meet all the requirements listed in this section and the manufacturers' recommendations. The irrigation system and its related components shall be planned and designed to allow for proper installation, management and maintenance. An irrigation design plan meeting the following design criteria shall be submitted as part of the Landscape Documentation Package:
(1) System.
(a) Landscape water meters, defined as either a dedicated water service meter or private
submeter, shall be installed for all nonresidential irrigated landscapes of 1,000 square feet and residential irrigated landscaped of 5,000 square feet or greater. A landscape water meter may be either
1. A customer service meter dedicated to landscape use provided by the local water purveyor; or
2. A privately owned meter or submeter.
(b) Automatic irrigation controllers utilizing either evapotranspiration or soil moisture sensor data utilizing non-volatile memory shall be required for irrigation scheduling in all irrigation systems.
(c) If the water pressure is below or exceeds the recommended pressure of the specified irrigation devices, the installation of a pressure regulating device is required 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.
(g) Flow sensors that detect high flow conditions created by system damage or malfunction are required for all non-residential landscapes and residential landscapes of 5,000 square feet or larger.
(h) Master shut-off valves are required on all projects except landscapes that make use of technologies that allow for the individual control of sprinklers that are individually pressurized in a system equipped with low pressure shut down features.
(i) The irrigation system shall be designed to prevent runoff, low head drainage, overspray or other similar conditions where irrigation water flows onto non-targeted areas, such as adjacent property, non-irrigated areas, hardscapes, roadways or structures.
(j) Relevant information from the soil management plan, such as soil type and infiltration rate, shall be utilized when designing irrigation systems.
(k) The design of the irrigation system shall conform to the hydrozones of the landscape design plan.
(l) The irrigation system must be designed and installed to meet, at a minimum, the irrigation efficiency criteria as described in § 153.160.110 regarding the Maximum Applied Water Allowance.
(m) All irrigation emission devices must meet the requirements set in the American National Standards Institute (ANSI) standard, American Society of Agricultural and Biological Engineers'/International Code Council's (ASABE/ICC) 802-2014 "Landscape Irrigation Sprinkler and Emitter Standard", All sprinkler heads installed in the landscape must document a distribution uniformity low quarter of 0.65 or higher using the protocol defined in ASABE/ICC 802-2014.
(n) It is highly recommended that the project applicant 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.
(o) In mulched planting areas, the use of low volume irrigation is required to maximize water infiltration into the root zone.
(p) Sprinkler heads and other emission devices shall have matched precipitation rates, unless otherwise directed by the manufacturer's recommendations.
(q) Head to head coverage is recommended. However, sprinkler spacing shall be designed to achieve the highest possible distribution uniformity using the manufacturer's recommendations.
(r) Swing joints or other riser-protection components are required on all risers subject to damage that are adjacent to hardscapes or in high traffic areas of turf grass.
(s) Check valves or anti-drain valves are required on all sprinkler heads where low point drainage could occur.
(t) Areas less than ten feet in width in any direction shall be irrigated with subsurface irrigation or other means that produces no runoff or overspray.
(u) Overhead irrigation shall not be permitted within 24 inches of any non-permeable surface. Allowable irrigation within the setback from non-permeable surfaces may include drip, drip line or other low flow non-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.
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 § 153.160.100(A)(1)(h). Prevention of overspray and runoff must be confirmed during the irrigation audit.
(v) Slopes greater than 25% shall not be irrigated with an irrigation system with an application 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 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 shall be placed on separate valves from shrubs, groundcovers and turf to facilitate the appropriate irrigation of trees. The mature size and extent of the root zone shall be considered when designing irrigation for the tree.
(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.
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 which is required in the Water Efficient Landscape Worksheet. This table can also assist with the irrigation audit and programming the controller.
(B) Irrigation design plan requirements. The irrigation design plan, at a minimum, shall contain:
(1) The point of connection to the public water supply, and location and size of separate water meters for landscape.
(2) Location, type, size and manufacturer 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 § 153.160.190.
(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."
(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 Cal. Bus. & Prof. Code §§ 5500.1, 5615, 5641, 5641.1, 5641.2, 5641.3, 5641.4, 5641.5, 5641.6, 6701 and 7027.5, §832.27 of Title 16 of the California Code of Regulations and Cal. Food & Agric. Code § 6721.)
(Am. Ord. 1379, passed 11-4-15)