Theresa Park Nursery is Open for Business

Downes Wholesale Nursery, Theresa Park is Open for Business!

After 20 months of planning and construction, we are pleased to announce that Downes Wholesale Nursery at Theresa Park is open. Our ‘super’ nursery is 145 Acres and has the capacity to hold several million plants. From the onset of this project our goal has been to create a nursery that will act as a benchmark for others to follow.

We now have around 600,000 plants on the ground and steadily building up by the day. We would like to welcome anyone who would like to come and inspect the site.

Brooks Irrigation have put the finishing touches on Rain Bird SiteControl irrigation control system. SiteControl also has the ability to use a tipping bucket rain sensor to detect and suspend irrigation while measuring rainfall. When rain stops, irrigation resumes with run times reduced according to measured rain saving us precious water. Another outstanding feature of SiteControl is the ability to communicate with the pump station and optimise irrigation, pump station flow rate, pipe sizes and sprinkler types are programmed into the system. SiteControl can then work out how many solenoids it can run together keeping the pump at its maximum flow and efficiency.

Here are some statistics for the site so far: 90,000m3 earth moved, 8km irrigation pipe, 4 acres of Shade cloth, over 3km of racks for 75lt – 400lt trees, 3km communications wire for irrigation, 10 acres of plastic for lining beds, 4000+ m3 gravel, 72m long indoor plant shed.

View Downes Wholesale Nursery
View of Downes Wholesale Nursery 145 acre nursery near Sydney

Here is an overview of the project.
After 6 months of searching, trying to find a suitable property to expand our increasingly busy nursery we located a beautiful 145 ace property with over 1km of river frontage on the Nepean River at Theresa Park.

Before construction could begin we had to work out a number of factors, the biggest being water usage. We wanted to ensure a zero run off policy so we can recycle and purify all water run. One of the biggest obstacles was to control water flow, as the natural lie of the land did not fall as required. We enlisted the help of TRN Earthmoving who were able to achieve a cut/fill balance of approximately 90,000m3 on site hence eliminating the need for expensive fill import/export operations. There are two massive swales over 500m long which were constructed for a wetlands area for water purification.

The next concern was irrigation; pump stations, irrigation controllers, storm watch protection, weather stations, piping etc. As there are few nursery projects of this scale in Australia we had to conduct a lot of testing and research. We came up with a design for one of the largest pump stations I have seen in any nursery in Australia.

A Grundos pump station was chosen with 4 Variable Frequency Drive (VFD) pumps. The biggest advantage of a VFD pump is that it works by gradually winding up each pump in turn increasing pressure to a pre-programmed point and maintaining this pressure as solenoids turn on and off. A storm watch system was installed to protect the pump station from electrical surges, it measure the electrostatic charge in the atmosphere and can detect lightning from up to 5km away. When lightning is detected, it slowly winds the pumps down and then shuts the power off, and disconnecting the contactor switches.

Construction of plant beds further improved our water recycling program. Each plant pad was formed into a shallow dish and lined with plastic to stop water penetrating into the ground.

The dish has been lined with Ag pipe that guides the water to a drain system, leading to our wetlands for recycling and purification. Over the plastic and Ag pipe 100mm of crushed aggregate has been laid down as a base for the pots to sit on, reducing the risk of disease and providing excellent drainage.

We selected the Rain Bird LF1200 impact sprinkler for the majority of our overhead irrigation. This sprinkler is a low flow head and has a good size droplet with no misting. (Next time you see irrigation running, watch it closely and if you see a fine mist rising up above the sprinkler you are wasting water and increasing the humidity.)

To tie the irrigation system together and control the solenoids and weather sensors. We chose Rain Bird’s Site Control system which features an easy to use graphical interface that displays a map of the nursery on the computer and maps of the pipe work and solenoid valves which can simply be clicked on to make adjustments. One thing I have noticed is a lot of nurseries are often unaware of what their pumps are capable of. SiteControl can communicate with the pump station to check on available pressure and either turn on or off extra valves during the irrigation cycle which shortens complete cycle times. SiteControl can also communicate with temperature, anemometer and the rain tipping bucket and make adjustments to the irrigation cycle as needed (i.e. turn on frost control, pause irrigation during rain etc all helping to make sure water is used economically).

To control the solenoids we chose a two wire system, the principal of this system is simple. We used several kilometers of a two core cable that joined all solenoids, weather sensors, fertigation and any other devices that need controlling. A decoder was attached to the two wire cable which acted as a switch for solenoids. Rain Birds Site Control software recognizes the signal from each decoder where it can then operate the solenoid deriving power from the two 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 by simply splicing into the communication line and adding additional decoders and devices. Decoders are underground which reduces the risk of accidental damage as they require up to 80% less wire than a satellite system.