Design Guide

Slopes
Driplines should be located parallel to the contour of slopes
whenever possible. Since dripline runoff occurs on areas with a
slope of greater than 3%, consideration must be given to dripline
density from the top to the bottom of the slope. The dripline on the
top two-thirds of the slope should be placed at the recommended
spacings for the soil type and plant material in use. On the lower
one-third, the driplines should be spaced 25% wider. The last drip-
line can be eliminated on slopes exceeding 5%. For areas exceeding
ten feet in elevation change, zone the lower one-third of the slope
separately from the upper two-thirds to help control drainage.
Elevation Differences
When utilizing non-pressure-compensating dripline, elevation dif-
ferences of five feet or more require separate zones or individual
pressure regulators for each six-foot difference on uniform slopes
(see detail number 17, p. 31).
When working with rolling landscapes with elevation differences of
five feet or more within a zone, it is best to use pressure-compensat-
ing dripline to equalize pressure differentials created by the eleva-
tion differences.
Though vacuum relief valves aren’t necessary when installing Toro
dripline at-grade - even when mulching over - all subsurface irriga-
tion zones must have a vacuum relief valve at the highest point in
order to eliminate the vacuum created by low-line drainage, which
causes soil ingestion. This is especially crucial when the dripline
laterals are placed perpendicular to the contour of the slope as in
street medians. All subsurface dripline laterals within the elevated
area must be connected with an air relief lateral (see detail number
12, p. 28).
In-line spring-check or swing-check valves should be used on slopes
where low-line drainage could cause wet areas in the lowest areas of
an irrigation zone (see detail number 23, p. 34).
Landscape Dripline Design _____________________________________________________________
■ General Design Parameters
NOTES:
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