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Building Yet Another Concrete Pond in Panamá

by Carla Black, Volcán, Chiriquí
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This was the year of grand landscaping schemes in our yard. We were tired of the patchwork of "fruit" trees that never produced, and decided to make an ornamental garden of the flat area near the house. The photo below left was taken from the roof of the house before changes started. The work and compost-making shed is where the future pond will go, and the transverse vegetable beds are heaped with a cover crop, blocking easy access to the area.

A bit more than a year later, the vegetable beds are expanded into a round shape and allow access beyond. The shed is moved, and the new big pond hole is dug. The huge Musa thomsonii gave way to a manageable patch of Musella lasiocarpa - thanks to one little pup from Marie Fisher a few years ago! In the photo at the right you can catch a glimpse of a small pond on the right; it is nestled into the hillside and has a window in one wall so you can see the secret life of a pond under water. More on that next time! 


 
The pond is 40' (12m) in diameter and 2' (.6m) deep at the edge, sloping to 3' (1m) deep in the center. The concrete blocks define the level of the edge; on the right side the edge is at ground level, on the left, the blocks formed a wall before backfilling the walkway. We kept the pond hole wet with a sprinkler during dry weather previous to plastering.
 

 

Unseasonably strong afternoon rains had us worried for the whole week before the concrete plastering job began. We started work on day one with a double crew at 6:00 am to beat the daily downpour, and rounded up large sheets of plastic as insurance against rain. Eight cubic meters of sand had been sifted in the previous days and was ready to mix. One hundred sacks of cement were close at hand. 


The first idea was to plaster a layer of cement onto the wall and press the metal lathing into it. That plan didn't really work in practice, so the mesh was tacked onto the wall and set into the first layer of cement on the floor.
 

It was important to bend the wall mesh onto the floor to unite the floor and wall, which is a joint vulnerable to cracking. The cement was troweled on, and passed through the mesh satisfactorily.


Once the wall was done, the floor work went as fast as the cement came out of the mixers.
 

One hundred sheets of metal lathing help make the pond one
single ferro-cement unit, very resistant to cracking.


The other important step in making the pond watertight was in troweling each layer in one go. If we had left off half way and started again the next day, the resulting seam would have been difficult to seal. The workers are pinning down unruly corners of metal with dabs of cement and rocks. 
 

At the end of day one the pond has one entire coat of cement with lathing pressed into it. Because of the preparation and big crew, we finished work at 11:00 am, covered the pond with sheets of plastic, and survived the deluge that began at noon!


The next day Ivan was at work at dawn brushing and sweeping away loose bits of cement that could form pockets as the second coat of cement went on.
 

The crews worked in from the side, putting on an even (and supposedly) rather thin coat of cement. A thick layer of cement is no stronger than a thin one.


Again we were done before noon on day two, and the pond looked official.
 

The tropical downpour started right on the mark of 12:00, and we rushed to drape the plastic over the fresh cement to keep it from rinsing down the center drain.


The following day, 24 hours after finishing the cement work, we began to fill the 22,000 gallon pond with two garden hoses. It took all night, all day, and all night! We drained the pond after a week to rinse away cement residue and to paint any visible cracks with flexible water-seal paint. We also painted the juncture of concrete with PVC at the inlets and drain tubes. The paint we have used successfully is Drylok from UGL; Watertite from Zinsser is a similar product.
 

I've been dividing lilies in preparation for planting the pond and it gobbled up 30 plants set in plastic washbasins. I have a warm tank in the house now with baby Victoria 'Longwood Hybrids', one of which will have all the room it needs to grow in our new pond.
Now it is only a matter of time!

Building a Concrete Pond in Panamá, First Edition

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