Subsurface drip systems
Drip irrigation has been used for
many years in agricultural settings but has only been
employed successfully in the United State to distribute
wastewater since the late 1980s. Most of the initial
experience with drip technology has been in the Southeastern
United States. In the past few years the technology
has garnered widespread interest nationally and there
are now a number of states that are conducting research,
developing standards and/or actively permitting these
systems.
A subsurface drip system (SDS) is an efficient pressurized
wastewater distribution system that can deliver small,
precise doses of effluent to shallow subsurface disposal/reuse
fields. SDS distribution piping is small diameter, flexible
polyethylene tubing (dripline) with small in-line emitters
(orifices that can discharge effluent at slow, controlled
rates, usually specified in gallons per hour). Dripline
can be trenched (by hand or with a trenching machine)
into narrow, shallow trenches (see Figure 1 below) or
plowed (with a vibratory plow or other insertion tool)
directly into the soil and backfilled without gravel
or geotextile. Typical installation depth is between
6 and 10 inches.
Advantages of Subsurface
Drip Systems
- Installation of dripline
is less site-intrusive and simpler than installation
of conventional gravel-filled trenches. A backhoe
is not needed, nor is gravel or geotextile.
- Flexible dripline can be
installed in grid or irregular patterns as needed
to accommodate contours on sloped sites, irregularly
shaped areas, difficult site conditions, or
landscape irrigation applications.
- Small diameter dripline
can be pressurized quickly resulting in very
even distribution.
- Low flow rates allow for
longer lateral runs than can be obtained with
conventional piping.
- Shallow placement of dripline
can enhance treatment by maximizing soil depth
and delivering effluent to a point in the soil
profile where there is typically more oxygen
and organic material.
- A vegetative cover
over the dripfield (usually turf) provides additional
treatment and reuse through plant evapotranspiration.
- Slow, controlled emitter
discharge combined with multiple daily dosing
enhances aerobic conditions in the soil and
results in frequent drainfield resting periods.
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To view the
complete Recommended
Standards and Guidance for Performance, Application,
Design, and Operation and Maintenance of the Subusurface
Drip Systems you may follow the following links:
Subsurface
Drip Systems
(Effective Date: January 15, 2002) - in Adobe Acrobat
Format.
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