(A) For the efficient use of water, an irrigation system shall meet all 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. An irrigation design plan meeting the following design criteria shall be submitted as part of the landscape documentation package.
(1) System.
(a) To facilitate water management, dedicated landscape water meters are highly recommended on landscape areas smaller than 5,000 square feet.
(b) Weather-based irrigation controllers, soil-moisture-based controllers or other self-adjusting irrigation controllers 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.
(2) Sensors (rain, freeze, wind, and the like), either integral or auxiliary, that suspend or alter irrigation operation during unfavorable weather conditions, such as rain or a freeze, 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.
(3) Manual shut-off valves (such as a gate valve, a ball valve or a 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.
(4) Backflow-prevention devices shall be required to protect the water supply from contamination by the irrigation system. A project applicant shall refer to the City Code, the City Public Works Design Standards, the Oregon Plumbing Specialty Code (latest version) and the Oregon Health Authority rules (OAR 333, Div 61), regarding cross-connection and backflow-prevention requirements.
(5) High-flow sensors that detect and report high-flow conditions created by system damage or malfunction are recommended.
(6) 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.
(7) Relevant information from the soil management plan, such as soil type and infiltration
rate, shall be utilized when designing irrigation systems.
(8) The design of the irrigation system shall conform to the hydrozones of the landscape design plan.
(9) The irrigation system must be designed and installed to meet irrigation efficiency criteria. For the purpose of determining maximum applied water allowance, average irrigation efficiency is assumed to be 0.71. Irrigation systems shall be designed, maintained and managed to meet or exceed an average landscape irrigation efficiency of 0.71.
(10) 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.
(11) In mulched planting areas, the use of low-volume irrigation is required to maximize water infiltration into the root zone.
(12) Sprinkler heads and other emission devices shall have matched precipitation rates, unless otherwise directed by the manufacturer’s recommendations.
(13) Head-to-head coverage is recom-mended. However, sprinkler spacing shall be designed to achieve the highest possible distribution uniformity using the manufacturer’s recommendations.
(14) Swing joints or other riser-protection components are required on all risers subject to damage that are adjacent to high-traffic areas.
(15) Check valves or anti-drain valves are required for all irrigation systems.
(16) Long, narrow or irregularly-shaped areas, including turf, less than 8 feet in width in any direction, shall be irrigated with subsurface irrigation or low-volume irrigation technology.
(17) Overhead irrigation shall not be permitted within 24 inches of any nonpermeable 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:
(a) The landscape area is adjacent to permeable surfacing and no overspray or runoff occurs; or
(b) The adjacent nonpermeable surfaces are designed and constructed to drain entirely to landscaping; or
(c) 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. Prevention of overspray and runoff must be confirmed during irrigation audit.
(B) Hydrozone.
(1) Each valve shall irrigate a hydrozone with similar site, slope, sun exposure, soil conditions and plant materials with similar water use.
(2) Sprinkler heads and other emission devices shall be selected, based on what is appropriate for the plant type within that hydrozone.
(3) Where feasible, trees shall be placed on separate valves from shrubs, groundcovers and turf.
(4) Individual hydrozones that mix plants of moderate- and low-water-use or moderate- and high-water-use may be allowed if:
(a) Plant factor calculation is based on the proportions of the respective plant water uses and their plant factor; or
(b) The plant factor of the higher-water-using plant is used for calculations.
(5) Individual hydrozones that mix high- and low-water-use plants shall not be permitted.
(6) On the landscape design plan and the irrigation design plan, hydrozone areas shall be designated by number, letter or other designation. On the irrigation design plan, the areas irrigated shall be designated by each valve, and a number shall be assigned to each valve. This valve number shall be used in the hydrozone information table. This table can also assist with pre-inspection and final inspection of the irrigation system, and in programming the controller.
(7) Irrigation design plan specifications. Irrigation systems shall be designed to be consistent with hydrozones. The irrigation design plan shall be drawn on project base sheets. It shall be separate from, but use the same format as, the landscape design plan. The irrigation design plan shall accurately and clearly identify:
(a) Location and size of separate water meters for the landscape.
(b) Location, type and size of all components of the irrigation system, including automatic controllers, main and lateral lines, valves, sprinkler heads, moisture-sensing devices, rain switches, quick couplers, and backflow-revention devices.
(c) Static water pressure at the point of connection to the public water supply.
(d) Flow rate (in gallons per minute), application rate (in inches per hour) and design operating pressure (psi) for each station.
(8) At a minimum, the irrigation design plan submitted to the local agency shall follow standard industry practices and applicable local agency requirements, including:
(a) Location and size of separate water meters for landscape;
(b) 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;
(c) Static water pressure at the point of connection to the public water supply;
(d) Flow rate (in gallons per minute), application rate (in inches per hour) and design operating pressure (psi) for each station;
(e) The signature of a licensed landscape architect, certified irrigation designer, irrigation consultant, licensed landscape contractor or any other applicable landscape professional or person, licensed or unlicensed, authorized to design an irrigation system.
(f) Irrigation schedules satisfying the following conditions shall be submitted as part of the landscape documentation package.
(g) An annual irrigation program, with monthly irrigation schedules, shall be required for the plant establishment period, for the established landscape, and for any temporarily irrigated areas.
(C) Maintenance schedules. A regular maintenance schedule satisfying the following conditions shall be submitted as part of the landscape documentation package:
(1) Landscapes shall be maintained to ensure water efficiency.
(2) A regular maintenance schedule shall include, but not be limited to, checking, adjusting and repairing irrigation equipment; resetting the automatic controller; aerating and dethatching turf areas; replenishing mulch; fertilizing; pruning and weeding in all landscaped areas.
(Ord. 2021-12-01, passed 1-11-2022)