wastewater disposal and water supply preliminary report woodlane

2.2.2 Irrigation
Class B treated effluent from the wastewater treatment plant is pumped to
irrigate a woodlot through an inline dripper system with sight glass and
manifolds. The land for the woodlot is currently owned by Council, including the
adjacent open field between the woodlot and the treatment plant, approximately
1.6km from the river and at an AHD of approximately 50m.
Initial design documentation implied that a supplementary water supply would
be required during the early growth period of the woodlot, by utilising the
sewerage system to pump river water to the site. This is also shown on
Drawing 91632/P01 (for tender only) with a temporary line connected into the
flushing manifolds on the western side of the woodlot. No other details such as
the temporary period required, the supply route and type, and location of
provision point are available on any drawings.
Site investigation reveals the presence of a few PE pipes near the woodlot, with
a 60mm dia. pipe entering the woodlot from the south-western corner, similar to
what is shown on Drawing 91632/P01 (see Appendix P Photos 22 and 24),
possibly suggesting that this could be the temporary water supply line. The two
flushing valves on the downstream of the supply line have also been located on
site, however they were found to be disconnected at the time of investigation
(see Appendix P Photos 20 and 21).
What isn’t shown on the drawing is the presence of another 40mm dia. pipe
which tees off from the 60mm dia. pipe at the south-western corner of the
woodlot, and it appears that it eventually also enters the woodlot at
approximately mid-way along the western perimeter (see Appendix P Photo
22). A water meter was also found at the upstream of the tee-junction along the
60mm dia. pipe with reading 003909 m 3 at the time of inspection, dated 13
December 2007 (see Appendix P Photo 23). An isolation valve for each pipe is
also present downstream after the junction. The exact origins of these two
pipes are unclear as they are buried further upstream.
Interestingly a second 40mm dia. pipe was found to run parallel with the first
one, also buried upstream but was seen to continue to run along the western
and northern perimeters of the woodlot, before going onto the western side of
Woodlane Wastewater Disposal and Water Supply Preliminary Report
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