Day Three - 16th September 2016
It’s been two days since my last visit and I can’t
believe the progress the build team has made. Not only has the concrete base of
the cistern been set, but the walls of the cistern are up, and the metal work
for the “gorro” or cap is laid out on the ground.
Cement is applied first in one direction
(horizontal), then after a short period for layer-one cement to set up, a
second layer is overlaid in the opposite direction (vertical).
The
bidirectional application makes for tough and water-tight walls. I am amazed to
learn that, when full, the walls flex. Okay, the walls don’t actually bulge,
but the ferro-cement expands dynamically under the weight of the water.
The
“masa” or concrete mud for the gorro is mixed at a ratio of four parts cement
to one-part sand, and significantly stiffer than the walls because the wet mix
is applied directly to the metal mesh without the aid of plywood backing.
The gorro is equipped with an access door to permit
maintenance on the interior of the cistern.
And the exterior of the cistern is fitted with a clever, but commonsense water level gauge. A clear plastic hose will be connected between the water spigot at the bottom of the cistern and a narrow diameter pipe protruding from the top of the cistern. As the interior water level is drawn down, there is a corresponding drop in the water level in the transparent hose.
Recommended cistern maintenance consists of two primary elements: 1) yearly brushing of interior walls, and 2) if the catchment roof surface is of any material other than concrete or tin, then it must be repainted annually.
Next stop, the final
finish work.
Guest post by Roger Brudno.
