Breaking ground
Due to limited access a three tonne excavator was used to clear the
ground and remove the spoil. Existing retaining walls and concrete bases
were removed using a hydraulic “pecker”. The concrete was found to be
double wired with A393 mesh and proved to be stubborn to be removed.
Persistence prevailed and after 12 days we had a hole. Levels were taken
from our datum point and checked against excavation depths, where any
adjustments that needed to be made, were necessary. In total 350 tonne
of spoil was removed from the site.
12000 Gallon Koi Pond Project - Construction
Outlined over the pages
below is a detailed description of how Reflections constructed a
12,000 gallon Koi pond.
Prime Base
On this project our chosen filtration system dictated what kind of
concrete base would be deployed. We will go into these considerations
later. Two bottom drains were needed to give us two 4” outlets, these
drains were also to be aerated via diffuser membranes. A 300 mu Visqueen
sheet was laid to the whole excavation – this has two benefits:
1/ to keep the water in the concrete for initial cure
2/ to keep the entire construction dry for GRP application
Two 225mm discharge sumps with 4” lines were installed into prepared
channels and concreted to correct locations and levels. Reinforcing bar
was added to the sump locating concrete which would then tie to the main
pond base.
A C35 Kn base was then laid to the entire area. This concrete was
compacted using a 1.5” vibrating poker. The base was levelled using an
aluminium tamp.Many thanks go to Precision Poured Concrete for getting
the concrete to a difficult location. Wall Construction
Our chosen method for constructing this Koi pond was to lay dense
concrete blocks. The blocks were to be laid flat which gives a 225mm
wide wall x 100mm course. The Koi pond TPR & mid water filter feed were
located into this block work and the pipe work was left as “stubs” to be
utilised when the final connections were necessary. The entire perimeter
of the pond wall was backfilled with 10mm pea shingle which allows
drainage and also protection of the pipe work. Render
A render mix of three sand : one cement : 1.5 kilo of cem FIL fibre was
used to render the blockwork to provide a suitable finish for the GRP
(fibreglass) to be applied. The cem FIL is a special alkali resistant
fibre that when utilised correctly will provide an ideal mechanical key
for the GRP. All the walls were coated with a primer prior to the render
application.
The Koi pond base required that falls be laid to each Koi pond drain to
facilitate waste removal. The base dishing was accomplished using 6m3 of
ready mixed flooring screed, this screed also had the fibres added.
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