Well done on doing your research and then heading to this forum to ask your questions. I apologise for our delay in responding to you.
I believe I can answer your questions based on discussions with our partner contact at CfAT, however let me know if you have any further questions and we can assist you with finding the answers as best we can.
Firstly, it would be useful for you to read project opportunity ‘5.2 Mobile solar-powered bore pumps’ in the Water management design area page and associated photos and resources if you haven’t already, including an interactive with further technical information on an example solar bore pump in Cape York.
To answer your questions:
– The bore would be 100m deep at least ideally
– This would be a fairly reliable water source however making the bore deeper would increase reliability in case the ground water level drops or the pump reaches silting at the bottom, as the submerged pump floats with the water level. Often there are backup water supply sources and systems on Cape York where water is needed at all times, such as rainwater tanks or river water pumps if there is an appropriate water source nearby. So you might consider a backup system – whether water, or e.g. high pressure air, if the bore water fails.
– Maintenance of the bore you should be able to determine as best you can by looking at the interactive mentioned above on the solar powered bore example on Cape York, based on the technology it uses in the images and text information provided about how it works. There will likely be elements that local workers e.g. rangers could maintain or check for the washdown station, and as a guess perhaps every 1-3 years it might need a specialist. Or, you can also research what maintenance is required for fixed bore pumps with similar parts to inform this. I suggest considering how you will communicate to local workers how to use and maintain it as part of your solution – whether it be training or diagrams on the bore to assist with this to reduce external involvement and costs and large delays for this.
– Our contact at CfAT said that bores with PVC piping can last up to 20 years before they need to be replaced.
– Our contact at CfAT said solar bore pumps cost around $10,000 – however you will need to add on labour as well as maintenance. As mentioned above, the cost of maintenance will be determined by the key elements of the bore and you should be able to estimate this depending on who will maintain those parts (e.g. rangers, external specialists) and how frequently. Keep in mind that maintenance budgets are also heavily dependent on who the key stakeholder is that you are suggesting implements the solution and how much money they have to put aside.
I hope this helps answer your questions, but as mentioned feel free to follow up to clarify by commenting here.
Best of luck with your project,