News from Downes Wholesale Nursery: Theresa Park Nursery update.

To control the solenoids we have chosen a two wire system. The principal of this system is simple. We have used several kilometers of 2 core cable that joins all solenoids, weather sensors, fertigation and basically any other devices that need controlling. A decoder is attached to the 2 wire cable which acts as switch for solenoids. Rain Birds Site Control software recognises the signal from each decoder where it can then operate the solenoid deriving power from the 2 wire system. It essentially acts like a giant computer network that you can keep plugging devices into. Decoders provide the advantage of easy system expansion, simply splice into the communication line and add additional. Decoders and devices, decoders are underground reducing the risk of accidental damage, and they require up to 80% less wire than a satellite system.

A surge protector has been added to the 2 core wire approximately every 100 metres, If lightning strikes a valve or the ground, damaging the wire, we can easily locate the fault and pull out the damaged wire between the surge protectors.

Each solenoid has had Rain Bird's pressure regulator installed. This provides an excellent means of regulating outlet pressure at the valve regardless of incoming pressure fluctuations. The visible scale makes it a snap to adjust pressure as we are using several types of sprinkler heads and drippers that perform at their best at different pressures.

We have created a series of weirs in the main swale that collects water going back to the dam. The swales are about 500 metres long, and act as settling ponds for silt and debris. They will be planted out shortly with aquatic species, even without planting they are already providing great results. Our current run off is clear by the time it's half way through the swale. As the water moves slowly from weir to weir more debris settles in each one. The base has also been filled with gravel. In about 30 days bacteria will build up on the gravel and act as a biological filter as water flows through it, further helping to improve water quality.

To supplement our water supply we have installed a large submersible pump in the river, which operates at about 25 litres a second. The pump operates automatically with sensors at the full mark and 500mm below full ensuring the dam is always topped up. The pump station was installed with the aesthetic properties of the river in mind. A large concrete block to stabalise the pipe work was placed at the water level. All pipe work placed underground in the bank so its not visible this also helps protect the system during flooding.