Attachment K - HSTP Design

5.2

Spray Irrigation (utilizing fixed outlets).

Spray Irrigation systems shall

be managed to ensure the even distribution of treated effluent across the
designated Land Application Area

have boundary delineation designed to deter grazing livestock, animals, vehicles
and casual access by humans

be constructed to prevent effluent ponding or run-off within or from the surface
of the land application area

allow no spray to reach areas normally occupied by humans or animals

control the droplet size, throw and plume height so that aerosol dispersion and
wind drift is negligible. The plume height shall not be more than 500mm above
the natural surface of the irrigation area and must not exceed 2m diameter

have a semi flexible robust system of pipes/fittings permanently buried and fixed
have sufficient spray fittings to distribute the applied effluent evenly and
efficiently (determined by the plume size). The number of, and hydraulics of the
final number of spray outlets may require the use of a indexing/dosing valve
mechanism

have pipes and fittings rated to withstand a minimum of 150% of the shut-off
head of the irrigation pump

ensure the effluent does not come into contact with people, domestic or farm
animals or any crops intended for human consumption

have pipes buried to a depth of at least 100mm and the irrigation system shall be
permanently installed

have warnings, complying with AS/NZS 1319, at the boundaries of the
designated area in at least two places, clearly visible to property users with
wording such as “Recycled Water — Avoid Contact DO NOT DRINK”

have the presence of the buried supply lines indicated using underground marking
tape (to AS/NZS 2648.1:1995) or appropriately marked purple striped pipe.

Polyethylene complying with AS/NZS 4130:2009 and AS/NZS 4129:2008 (Int), PVC Class 12
complying with AS/NZS 1477:2017 is suitable for the header and main pump pipework.
UPVC pipes and fittings and garden hoses and fittings are not suitable. Optimum
performance from drip irrigation systems is obtained using high quality secondary treated
effluent, or better, having BOD; and suspended solids of 20/20 g/m’ to 15/15 g/m’.

Pump Systems shall

have a separate effluent pump chamber/tank volume of at least 200It with an
additional emergency storage volume of 24 hours flow rate

match the electrical starting requirements of the irrigation pump motor

have performance characteristics that match the hydraulic characteristics of the
irrigation system

have a discharge of at least 50% greater than the maximum 30 minute flow rate
have a visual and audible alarm system (with muting ability) for breakdown
notification

not be located adjacent to bedrooms, living rooms or recreational areas of
neighbouring properties

be contained in an acoustic chamber to reduce noise emission of all equipment to
a level not exceeding 40 dB (measured as fast response at a distance of 1m).

 

Unearthed Geotechnical P/L. 9 Design Report 023-038