OFF GRID Rainwater Harvesting – Part 1 concrete foundation

Excavating the Site for the Tank

So the real work starts with shovel and wheelbarrows — with the occasional break to pet a cat.

excavating a level place for the rain tank

When this spot is flat and level I then dig a trench for a drain.

levelling a spot in the garden for the tank
OFF-GRID Rainwater Harvesting - digging a drain trough

Water that accumulates inside the curb walls needs to drain away. This trench will move water from under the tank and to a dry well where it will absorb into the ground — more on that later.

Build the Forms

making the concrete forms from 1x8 lumber

I’ll build the forms from 1×8’s. With the inside form walls made in two pieces.

making the concrete forms from 1x8 lumber

They have a 45 degree cut to make stripping the inside forms easier.

making the concrete forms from 1x8 lumber

A mending board across this cut will hold the form together during the pour.

Building the Outer Form Walls

assembling the concrete forms

Cleats added to these 1×8’s will make attaching stakes easier as well as clamping the forms together on the ends.

assembling the concrete forms

And then I can screw the outside form walls together.

Rainwater Harvesting System - locating the forms off the pavilion

And I’ll line up this wooden box to the pavilion piers.

Secure Form Walls with Stakes

setting concrete forms in place and securing with stakes hammered into the ground

Then pound in stakes and screw them to the form cleats.

OFF GRID Rainwater Harvesting System - levelling forms for concrete

Checking and adjusting for level and square as I go along.

squaring forms with a tape measure corner to corner

Then the inside walls are clamped then screwed together.

assembling the concrete forms

Inner Walls added, Squared, and Levelled

They are levelled and squared and temporary spacers added.

OFF GRID Rainwater Harvesting System - levelling forms for concrete

Some of the stakes were too tall so I trimmed them with a hand saw.

sawing the form spikes down

With the forms in place I then add the pipes to the dry well.

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