Cistern to use seasonal creek to irrigate lawn

Jeff in Poway

Greetings,

I have a seasonal creek that runs the length of my 160' back lot line. Normally the creek has water flowing from November tthu June. I'm restoring the creek bed - and as part of this project, I want to iinstall a cistern tank intended for bulk storage of this run-off water. I plan to bury a 850 gallon poly underground cistern - rated for this and will place a pump and float valve system on top - tie it into my existing irrigation system with proper valving to operate either system.

My question/concerns lies in the fact I just discovered that the seasonal creek is also the water table. My neighbor poured footings for a retaining wall on his side of the creek in july, well afer the creek has run dry, and a little water seeped into the footing area.

My questions: 1] If I put a cisten in below ground level how do I prevent the cistern from 'popping up' during periods of high water level? 2] Should I collect creek run-off via a screened duct into the top of the cistern, or should I create a bottom or side hole and then allow the water to percolate into the tank? Will both work? 3] If I top fill, then should I just keep it 30% full all of the time? 4] If I bottom fill the water tank, how do I prevent roots from clogging 5] Should I place the cistern in a gravel bed?

All for now.

Bondo

Ayuh,... I'll admit,... I've never Tried what you're proposing,....
But,...
I'd Think that you'd keep the cistern absolutely Full,.. Whenever there's Any flow from the creek,..
And when it's Full, it shouldn't try to lift up.....

I'd also Think that if you Bottom fill the tank, You'd have what's known around here as a "Shore Well".... Not a cistern at all....
And I can tell you that when the water goes down, or in your case the creek stops flowing,....
Shore Wells usually go Dry.....
But, if the water table is as High as you say,... It just might work...

Btw,....
No Matter What you do,... Tree Roots will follow the Water.....

Jeff in Poway

Thanks for your input Bondo - anyone else care to share experience or knowhow here?

I think I'll buy a 850 gallon tank, but limit usage to 500 gallons (i.e. limitsprinkler use @ 18GPM for 25 minutes and set the float switch height in the tank accordingly). I'll need to make bouyancy force calculations to see if the residual weight will off set the BF, but i need to factor in the weight of gravel or dirt on top as well, and could drop the tank low enough to put 1-2 fett of dirt on top.


Comments anyone?