Subsurface drip dispersal systems are designed to hydraulically accomplish two objectives:
Deliver a set volume of wastewater to the receiving soil or media and
Flush the interior of the drip tubing network to remove accumulated biological slimes or “re-growth”.
Most drip dispersal design manuals call for two distinctly different cycles – a dose cycle and a flush cycle. The two cycles are distinguishable by the position of a flush valve. When the flush valve is closed, the system will dose effluent into the dripfield at arelatively high inlet pressure and low flow. When the flush valve is open, the system will flush the piping network at a low inlet pressure and high flow rate.
In addition to the two types of cycles, there are two traditional ways to accomplish the flush cycle: automatically or manually. Automatic flushing is accomplished using complex control equipment and electronic valves, synchronized with the pump. Flushing occurs automatically at prescribed time intervals. Manual flushing is accomplished with the use of simple ball valve(s) and requires an operator to periodically open and close the valve(s). A third option is called “continuous flush”.
With “continuous flushing”, both the minimum pressure for dosing and the minimum flow for flushing are achieved during every dose cycle, simultaneously. (The emitters used in this application must be pressure compensating. Pressure compensating means that within a given pressure range (7 to 60 psi) each emitter will discharge at the same rate, within a very narrow range. The flush valve position is static and does not require any adjustment between the dosing and flushing cycles. Flushing velocities can vary from each system design from 1 to 3 ft/sec. Differing velocities can be used depending on the cleanliness of the effluent or other design consideration.
Regardless of the flushing method (manual, automatic, or continuous) all systems must be designed to accomplish a dose and flush cycle. The number of emitters, zones, laterals within each zone and lateral lengths are all factors that determine the pump and supply line size and can affect the system’s ability to adequately prevent or remove slime build-up from the interior walls of the piping network.
The Lowridge continuous flush process has several basic parameters for design and operation. For virtually all single-family residence designs, the same headworks, pump, and dripline 0.42 gph Netafim Bioline® are used.
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Reverse Flush Headworks
When Lowridge Onsite Technologies developed the LOWeFLOW™ system, there were many design challenges to overcome. The number one challenge was how to cost effectively protect the drip emitters from clogging. The methodology we discovered we call “Reverse Flush”. We standardized the electrical controls and headworks that allow for an efficient reverse flushing of the disc filtering device and a forward flush of the drip tubing.
Custom controls and headworks
Lowridge engineers can provide any project with custom controls and headworks. We provide consultation services for all aspects of sub-surface drip design, at no charge. After the design parameters are established, Lowridge can manufacture the controls and headworks as specified.