MIL-HDBK-1011/1
e) Exercise care to ensure that debris from the trees does not
build up on roof surfaces and in roof drains, gutters and downspouts. Salt
spray and strong winds, common to coastal areas, contribute to corrosion of
metal building material and uncomfortable living conditions. Such conditions
may be reduced by planting windbreaks. Windbreaks consist of tight groupings
of plants that can withstand salt spray and strong winds. Proper root
anchoring systems are essential. Several rows of planting material may be
required to achieve maximum results. Wind may be reduced along the ground for
a distance of up to twenty times the height of the windbreak.
f) Periods of intensive rainfall often cause severe erosion to
slopes and embankments, and to unvegetated sites. Ground covers and grasses
which have good binding root systems are of primary importance in preventing
erosion and can be applied fairly economically by methods such as hydro
mulching. Trees and shrubs may also be used but do not substitute for the
ground cover/grass protection.
2.6.3
Landscape Irrigation System. An irrigation system is often used to
maintain ornamental landscaping in coastal and mid-elevation areas.
a) Generally, irrigation is necessary for areas receiving less
than 50 inches of rainfall per year. Evaluate each site separately before
making a decision regarding the use of an irrigation system. The amount of
seasonal rainfall and the precipitation rate of soil at the site are important
considerations.
b) Irrigation systems may range from an automatic sprinkler system
to a series of hose bibs that are manually operated. The automatic system is
the most desirable. It allows the system to be activated late at night,
thereby avoiding the higher evaporation rates associated with daylight hours,
and will not interfere with daytime activities. A precipitation rate of 1 to
1.75 inches of water per week is appropriate for most landscapes in tropical
regions. Also, analyze soil permeability to determine the exact watering
schedule. In valleys and at higher elevations, irrigation is less of a
priority.
c) Irrigation systems consisting of PVC pipes and irrigation heads
are highly recommended due to their resistance towards corrosive elements,
cost efficiency, and simplicity in repair/modification.
d) PVC pipes will deteriorate due to exposure to ultra-violet
light and may be easily damaged when used above grade. Install them at 12 to
18 inch depth. Use "pop-up" sprinkler heads in grass areas to avoid conflict
with foot traffic, and mowing equipment. Other areas such as ground cover or
shrubbery beds may be irrigated with fixed risers. This detail includes a
flex riser and a PVC coupler to facilitate any replacement due to breakage. A
swing joint detail may be used to further ensure against damage to the system.
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