In most zoological exhibits or gardens, water is utilized as one of the
main features or a focal point of the exhibit. This water feature can
be an architectural element in the form of a waterfall, pond, or river
and it may also be a habitat with fish, water birds, turtles, plants or
some type of ecosystem. Almost always it is an expensive artificially
constructed system with a liner and layers of concrete, shotcrete, and
steel or a combination of these materials. The finished product is often
an excellent replica of a natural system reflecting the geology of a specific
“value engineering” during the design process or simply because
there wasn’t enough money in the budget, the finished product may
be less then optimum from a design or a functional point of view. Perhaps
an existing pool or river is being redesigned as a new exhibit and changes
need to be made. With budgets always being tight, efficient and cost effective
methods are desired.
Jungle Island (PJI) there was a need to cover a percentage of the water
because the intense direct sunlight causes the water to heat up and dense
algae, both planktonic and filamentous, becomes a problem for the mechanical
life support system to remove. It also got impossible to view the fish.
The efficient way to control these algae was to cover or shade the water
through the use of plants. However with fish and turtles in the water,
floating plants were not a good option; they would end up as food for
the inhabitants of the water.
construction of PJI (the park has been open for less than two years) I
had the opportunity to work very closely with the site engineering subcontractor.
This contractor did all of the site excavation and drainage work. One
of the materials extensively used onsite for drainage was corrugated high
density polyethylene pipe (HDPE) pipe. It was easily cut with a chain
saw, very strong, and lightweight. When I was trying to come up with a
solution for the installation of plants in our waterway, I remembered
the HDPE pipe and did some research.
cut and cleaned pots ready for the waterways
click to enlarge
HDPE is the
most chemically inert of all commodity plastic raw materials. Engineers
have specified HDPE pipes for years in chemically active acidic or alkaline
site conditions. “Corrugated polyethylene pipe is the preferred
choice for installations that are subjected to acidic mine runoff, aggressive
landfill leachate or strong acids with a pH as low as 2.0. Plastics withstand
the effects of most basic and acidic chemicals, and polyethylene is one
of the most chemically stable plastics used in drainage pipe applications”
information in hand it seemed that HDPE pipe could work as planters and
I would not have to worry about the eventual release of toxins into the
water that could affect the fish and other animals. I called the superintendent
of the site engineering contractor and asked if they were working on a
project utilizing HDPE pipe and would they part with their scrap pieces?
The company eventually had a project with a large amount of scrap pipe
that ranged in size from 24” to 48” in diameter. We picked
up several van loads of pipe and then proceeded to turn them into planters.
planted pots with Leather Leaf fern
click to enlarge
the plan was to cut the pipe so that the planter would rise above the
water surface at most a few inches. The bottom of the planter had either
galvanized wire or plastic construction fencing attached by Zip-ties.
A liner of some sort of fabric was then placed on top of the wire. The
intent of this was to hold in the sand as we dumped it into the pot (it
already being in the water) so the sand would not spill out of the bottom.
Silica sand was used so the alkalinity of the water would not be affected.
Smaller pipe sizes were attached together in groups of three using Zip-ties;
larger pipe sizes, 42” and 48” were left as individual planters.
This was to make sure of a large heavy base so when the plants get bigger
they won’t be blown over by the wind.
of the planters have Leather Fern, Acrostichum danaeifolium planted
in them. We eventually left some planters up to a foot above the water
surface and planted them with palms. The palm species being used are Macarthur
Palm, Ptychosperma macarthurii, Paurotis Palm, Acoelorrhaphe
wrightii, and Licuala peltata. Other palm species will be
used as they become available in our nursery i.e. Red Sealing Wax, Cyrtostachys
renda and Nypa fruticans. Some other plant species used
are Pandanas sp, Philodendron sp, Anthurium sp,
and Alocasia odora.
Director of Horticulture
Parrot Jungle Island