Rainwater tank - backfilling and first collection!

Thursday, June 11: The beginning of another day of major transformation. Before.





Ferrying more gravel down the site...





The overflow pipe in place.



Once sufficiently covered in pea stone, the cistern is completely swaddled.





The inflow pipes are put in place.











It was raining as we hooked up the pipes... which meant the instant gratification of getting water in the cistern right away!
(this inflow setup was obviously temporary).
On the right, you can see the trickle of water coming from the filter overflow.



The gravel over and around the cistern is complete.



.. the final grading, at last. 2" of rigid insulation (4' wide) went in over the length of the inflow pipe - you can just see it peeking out at the far left.




Big thanks to our project sponsors:

Unit Precast for donating their labour (co-ordinating and installating the pump system)

ZCL for donating the massive fibreglass tank!

...

and to our excavators and earthmovers, Alltask Property Improvement.

Rainwater Tank Hookups

The plumber and electrician met on site with the folks from Unit Precast / RH20 to co-ordinate their systems. On the left (below) is the filter chamber, and on the right is the tank access manhole.







the pump



installing the inflow pipe



looking down into the tank



the tank outflow connection, through which water is sent back to the building



Here is the filter system in place. The white pipes are the overflow . The upper pipe is an overflow at the filter - about 5% of the inflow water drains away immediately, to get rid leaves and any other matter that might find its way along the eavestrough. The lower pipe is an overflow directly out of the tank. (Inflow pipes still to come.)



Big thanks to our project sponsors:

Unit Precast for donating their labour (co-ordinating and installating the system)

ZCL for donating the massive fibreglass tank!

The Patch

After some back-and-forth, it was decided that it would be most expedient to get the tank fixed by a local marine repair person rather than the Quebec-based manufacturer, ZCL. Our retired professor (and expert boat-builder) Mike Elmitt graciously stopped by to assess the damage and explain the basics of fibreglass work. Then one fine Saturday morning Mark and Bill came in to get the job done.



They built up three layers of glass fibre and resin to level out the break.





... and then topped it off with two layers a large patch over the whole area.









... and we were ready to go again.

The Backfilling .. and the Stall ...

Tuesday, May 20th > The slow backfilling process began. Pea gravel was layered in 18" thick around the tank, followed by the filter fabric, then 'a' gravel. Gravel was ferried down site scoop-by-scoop in the excavator's shovel. Native soil was only used to fill in the far corners.







Everything went swimmingly ...



... until right at the end of the day when, after much careful work, the excavator's bucket clipped the fibreglass tank, cracking it.





Luckily, the puncture was not big, and was above the overflow: an area that will never have water directly against it. Not a serious wound, but a stall in the process until we could figure out how best to get it fixed.

Craning in the tank; how the rainwater system works

The rainwater tank arrives!

. . . divertimento . . .

A brief description of the tank and rainwater collection system:

Tank Construction: Fibreglass
Capacity: 25 000 l.
Dimensions: 19'8" long x 8'6" dia.
Supplier: ZCL Composites (donation)

The system: All of the eavestroughs on the house run to a single point at the north east corner of the building. From here, rainwater drops into an 8" inflow pipe that runs underground toward the tank. The large diameter of the pipe is to prevent it from freezing up in winter. Near the filter, the 8" pipe breaks into two 4" pipes, which feed into the filter.

A submersible pump sits in the tank to move the rainwater into the house. The pump intake draws in water from within the middle of the water volume (not directly from the bottom of the tank). A layer of sediment may collect right in the bottom of the tank, and can be cleaned out periodically.

The rainwater will be used for flushing toilets and for outdoor watering. In the future, we hope to be able to use it for laundry and showers. Regulations don't currently permit these uses.
If the tank level drops too low (although this is unlikely, given its size), a float in the tank tells a solenoid valve in the house to switch over to city water, until the rainwater levels are replenished.

The rainwater collection system is also an important part of our site storm water management strategy. No storm water is sent off-site to city sewers. We have maintained permeable surfaces throughout the site; swales direct rainwater and allow for infiltration. The small amount of overflow from the cistern moves through a shallow swale and percolates into the ground.

. . . now, back to the feature presentation . . .

Unit Precast's craning truck snuck the tank through the canopy and brought it down site as far as it could reach ...













Then, the excavator picked it up and very carefully swung it into place.













...and everyone breathed a sigh of relief to see it settled in!

Big thanks to our project sponsors:

Unit Precast for donating their labour (co-ordinating and installating the system)

ZCL for donating the massive fibreglass tank!