Page 17 - Efficient Irrigation and Landscape Design Standards

IRRIGATION AUDIT
Jurisdictions should consider requiring irrigation systems be designed to a high distribution uniformity. Designers will be forced to create water-efficient designs, but this will then be confirmed after construction with a certified irrigation audit. The audit is a process where the system is turned on and water is captured in measuring devices to calculate uniformity.

An in-depth evaluation of the performance of an irrigation system shall be conducted by a certified landscape irrigation auditor. An irrigation audit includes, but is not limited to: inspection, system tune-up, system test with distribution uniformity or emission uniformity, reporting overspray
or runoff that causes overland flow, and preparation of
an irrigation schedule. The audit must be conducted
in a manner consistent with the Irrigation Association’s Landscape Irrigation Auditor Certification program or other U.S. Environmental Protection Agency “WaterSense” labeled auditing programs.
5.2 WATER BUDGET
ALLOWANCE
A Water Budget Allowance is a tool that allows regulators to verify water efficient measures are being employed during design. Calculations compare a baseline design, typically the entire site in turf with inefficient irrigation, and an efficient design. The water budget is established as an allowable percentage of the baseline design or a required amount of water savings.
Sprinkler heads shall be selected based on a distribution uniformity low quarter of 0.65 or higher using the protocol defined in American Society of Agricultural and Biological Engineers’/International Code Council’s (ASABE/ICC) 802- 2014 “Landscaped Irrigation Sprinkler and Emitter Standard.
The proposed Florida irrigation code, and City of Allen, Texas irrigation plan checklist included in the appendices include additional examples.
A catch can test is used to determine how long to run an irrigation system and how well the water is distributed over the landscape.
To provide for efficient use of water, a water
budget and irrigation schedule should be
developed and managed to utilize the minimum
amount of water required to maintain plant
health. The water efficient irrigation and landscape
ordinance should include requirements for
irrigation to be regulated by automatic irrigation
controllers and, at a minimum, rain sensor overrides should be provided to ensure irrigation is delayed during and immediately following rain events. The water efficient irrigation and landscape ordinance may establish allowable hours for irrigation, with irrigation scheduled for the evening hours when evaporation and evapotranspiration are minimized. The local jurisdiction should limit scheduled irrigation during the day, and may consider appropriate time limitations (in the range of 7:00pm – 10:00am). Exceptions may be permitted for performing audits of irrigation systems. It should be noted that switching to night-time watering typically results in at least 10% water savings so runtimes should be reduced accordingly.
EFFICIENT IRRIGATION & LANDSCAPE DESIGN STANDARDS 17