IrrigationNZ urges post EQ check on irrigation

IrrigationNZ urges post EQ check on irrigation systems

With the extent of damage to irrigation wells, pipelines and systems yet to be fully revealed in the wake of the 7.1 magnitude earthquake that struck Canterbury at the weekend, IrrigationNZ cautions farmers to take extreme care.

As power is restored there is potential for real danger in irrigation electrical systems, and this concern has farmers calling INZ for advice.

To some extent in respect to water it will be a case of “suck it and see”, however extreme care needs to be taken with electrical systems and if any obvious damage has occurred a qualified technician should be called for advice, INZ technical spokesperson Stephen McNally said.

McNally advises a few simple checks conducted prior to running systems would give some assurance around the integrity of bores, pumps and pipe networks ahead of the irrigation season.

Depending on the nature of ground disturbance bores may yield more or less than previously, and artesian bores may have a lowered static head.

“Expect the unexpected with regard to water flows,” McNally said.

Farmers with specific concerns or in need of technical support with their system to get it back up and running, and for help with assessing damage for insurance purposes, can contact INZ

Irrigation system checks post earthquake:

Below are guide-lines on to how to check you irrigation system and find out the extent of damage that may have been caused. IrrigationNZ recommends calling in specialist technicians to check out irrigation systems. Other points of contact for advice include the local irrigation supplier, IrrigationNZ at its national office on 03 3793820, or directly to INZ board members Stephen McNally stephen.mcnally@opus.co.nz or Ian McIndoe i.mcindoe@aqualinc.co.nz)

Power-Electricity:

Electricity is dangerous so assume live power.

Beware of surface water around electrical hardware and fallen lines or any other unusual observations. Turn off at mains if power cut, unless factors above make this too dangerous. If in doubt, do not touch.

Check for obvious damage, cut or obstructed lines, misaligned motors, switch boards, transformers and poles.

Call an electrician to check out properly before turning power back on.

Diesel-Petrol:

Look for obvious damage – leaks, broken fuel lines, damaged, misplaced and/or damaged motor or tanks.

Be aware of the presence of fumes. Petrol fumes in an enclosed space could be explosive.

Pumps-Motors:

Check for obvious misalignment or breakage between pump and motor, pump and pipe-work. Ensure all elements of the pump and surrounding above ground pipe-work are secure and cannot “fly off” on start up.

Starting pumps – start against closed head or as slowly as possible. Listen for unusual noises and stop if any are detected. Check for leaks on suction and delivery.

Check performance of pump for any obvious loss of performance in terms of the pressure and flow delivered.

Bore casings:

Using a test rod really requires the pump to be pulled and if the bore is of any depth a test rod could be very heavy. If the pump is not lifted then there will also be the issue of a test rod catching the rising column joints. CCTV (camera) is an option but may encounter murky water.

If the pump runs okay then the casing is probably satisfactory enough until a well driller can be brought on site. The key will be watching the water quality at the headworks and if any increase in sand is noticed in samples then pumping should stop.

Boreholes:

If possible discharge to waste at head-works rather than into pipes directly.

Check quality of water. Early indication is that water could be milky. Fill a glass with the milky water and let it stand, if it is air entrainment (micro bubbles) the water should slowly clear from the bottom up with no sediment at all. Fine particulates can also induce milky coloured water but these will generally settle downwards. If this is the case it is probably preferable to run to waste until it clears – if sandy then well will need to be redeveloped.

Head-works-valves-filters – check all above ground pipe, valves and filters for obvious misalignment and damage

Rivers:

Check ground around pump station and intake, intake structures, suction pipe and river channel.

Storage Dams:

Carefully check suction pipe particularly if through dam wall, look for signs of seepage.

Check integrity of dam as a whole, look for signs of seepage.

Pipe-work:

Run pump against closed valves to a test pressure of at least normal operating pressure and check for loss of pressure after the pump is stopped.

Big leaks – the system will be unlikely to reach cut-off pressure and somewhere in the system there will be evidence of surface leaking.

Small leaks – the system will reach cut-off pressure but over a quite short period of time the pressure will reduce.

No leaks – the system will hold its pressure.

Irrigators and Pivots:

Check irrigators for signs of stress damage, misalignment or damage to electrical wiring. Have a service technician make any necessary repairs.

Check control system wiring and irrigator automation equipment operation for faults.

Other systems: fixed sprinklers and drip-line –run system and identify and fix faults.

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