Development Standards | Design Standards—Landscaping and Irrigation
with groups including landscape professionals and water purveyors. c. The water budget will be calculated upon the total area of the site in landscape areas and in landscape water features (such as decorative ponds, pools or fountains) that are fed by irrigation water. For the purpose of calculating the water budget, “landscape area” shall mean the entire parcel, less:
f. The irrigation water use may be monitored by the water purveyor after the date of release of the performance bond. g. Alternative water sources such as recycled wastewater or rainwater are encouraged. Such water sources shall not be subject to the limits of the water budget.
3. Water use – Estimated water use calculated
The estimated water use shall be calculated using the following provisions. a. Estimated water use (EWU) shall be calculated for each hydrozone by using the following formula:
i. Sensitive areas and their buffers;
ii. The building footprint;
iii. Driveways;
iv. Paved portions of parking lots; and
EWU = (Eto) x (PF) x (HA) x (CF)
v. Hardscapes (e.g., decks, patios, sidewalks, and other nonporous areas). d. Areas such as playgrounds, sport fields, golf courses, school yards, or other recreational spaces where the turf provides a playing surface or serves other recreational purposes may be allowed additional water beyond the calculated water budget. In order to receive additional water for such turf areas, the applicant shall submit a statement designating such turf areas for recreational purposes and specifying additional water needs above the water budget. This additional water need will be based upon the Eto information for the turfgrass species or species mix used in such turf areas. e. Landscape water features shall not use potable water unless the water feature recirculates water used in its operation.
IE
Eto: Referenced evapotranspiration rate (net seasonal irrigation requirement in inches. See table in SDC 21.06.020J.2.)
PF: Plant factor value (see subsection 3.b. of this section)
HA: Hydrozone area (square feet)
CF: Conversion factor value of 0.62 (Eto inches to gallons per square foot)
IE: Irrigation efficiency value
b. Plant factor values shall be as follows, but may be adjusted pursuant to subsection 3. of this section:
0 to 0.3 for low water use plants
320 | Title 21: Sammamish Development Code
Effective | January 1, 2022
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