Part I. Basic Audits
Post‐Audit Considerations and Additional Activities
Other factors, such as ill‐suited irrigation piping diameter can also contribute to poor DU. Therefore, if this procedure indicates a zone has a poor DU and all sprinkler heads seem to be functioning correctly and at the same precipitation rate (they are all the same type and brand), additional adjustments to the system design may be necessary.
Some easily remedied factors that lead to a poor DU are tilted, blocked, sunken or clogged sprinkler heads, mismatched heads in a zone, and poor pressure regulation. Simple adjustments, cleaning, or maintenance may improve the DU. During the Irrigation System and Landscape Survey – Basic Audit (page 90), these easily remedied factors (problems with proper sprinkler head function) should have been identified and corrected.
This means you may need to consult an irrigation professional. If so, contact an individual certified by a trade group, such as the Irrigation Association1. Such an individual will be able to evaluate the complete system. The evaluator should not be affiliated with the contractor who would make modifications to the system to avoid possible conflicts of interest. Your facility’s intention to use separate contractors should be made clear and up front. 78
Another factor that can lead to poor DU is the layout of the heads. An irrigation system designed with head‐to‐head coverage will have a very high (efficient) DU. This means the sprinkler heads are spaced so the water from one sprinkler completely covers the distance to the next closest sprinkler (Vickers 2001, SJRWMD 2009) (Figure 30).
Florida Focus The Florida Irrigation Society (www.fisstate.org) can provide a list of certified irrigation system designers and other contractors.
Figure 30. Sprinkler coverage diagrams. a) An irrigation system without head‐to‐head sprinkler coverage (inefficient water application). b) An irrigation system with head‐to‐head sprinkler coverage (highly efficient water application). 1
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www.irrigation.org