Small pond for a school yard

Hi,
I'd like to build a small pond for a cemented school yard, so it's a hard surface, and I'm looking for ideas / examples of existing ponds, in similar environments.
The idea would be to make a raised pond, with something like a flowform to oxygenate water and make a small waterfall and water re-circulation.

It should host water plants, and even fish, if I manage to find a way for their maintenance/survival even during summer months when the school remains empty
and the heat is high (the school is in a Mediterranean city with very hot summers and very mild winters).

Right now the whole surface of the yard is a cement slab and I am considering filling the space with some 20-30 cm of garden earth, so the pond would be sitting on top of the earth
I am considering also, creating the pond container with a plastic liner (maybe epdm if I find a cheap source) held up by rocks.

One think I need to consider is where the outpput of the pond spillway will go. There is drain hole in the middle of the yard so I guess I might direct the terminal part of the pipe (?) that comes from the spillway till this drainage hole somehow.
Also, this drainage hole needs to be lined/screened to allow the excess water to penetrate but prevent the earth from ending in the hole (any ideas on how to do this well?)

From a micro-climatic point of view most of the yard is in shade all year round (even though there is more hours of shade in winter than in summer) having a NE aspect and having a building preventing the sun from hitting the ground until almost midday in winter and in just a few spots. In order to reduce evaporation in summer it might be better to site the pond in the more shady area, but I am not sure how this can affect the water plants or the fish.
Any idea/pointers welcome.

Howdy Antonio, You talked about the overflow from the pond going to a drain. Where is the water coming from? Will you continually add water to the pond?

The first thing that came to my mind was incorporating some sort of Aquaponics setup into the system. Then you could recirculate the water , help oxygenate it and filter it.

Hi Miles,
Well, as I said the school remains empty during holidays so having an acuaponic system may not be viable...nobody would feed the fish.
So I don't actually know if I can include any fish really, but I would be glad to see existing examples from other schools.
The water would come from the local city grid. Right now there aren't surfaces that we can use for water collection.
Thanks
Antonio

Is it a high school, or an elementary school? If it is an elementary school the pond will require safety measures, such as not deeper than 30-40 cm (water depth),  that will limit your design. Obviously that will also result in great fluctuations in water temp.
I guess I miss the whole point of adding soil on top of hard surface and then building pond on top of all. Why are you not building directly on top of the hard surface? I would build a wooden box from 50mm* 250mm (basically a raised garden bed), fill the bottom 30-50 mm with of sand and put liner on it. You can build it in any shape. I added some photos to give an idea what is on my mind (not as high as in the pictures, and not necessarily so small).
Ponds are very attractive features. Kids will be all over that area. You might want to limit the number of colored fish, such as koi and goldfish to control the attraction.

Hi,
well many thanks for you inputs. I didn't think actually to use wood but it's a really nice idea. The pictures you sent are really inspiring.

How would you include shelves with gravel where to plant marginal plants in these kind of structures?

And no, you are probably right, It can be better to actually build it touching the cement floor, but on the other hand it might be easier for the kids to fall inside it if it is lower.
Regards
Antonio

I don't like to create areas/zones dedicated to plants. It is harder to clean the pond when there are zones. I like to take everything out, clean it and rearrange the layout. So I plant everything in pots. For a deeper pond, I use two pots. I put the first pot upside down (usually a bit bigger and something heavy) and then put the second one on top of the first one. Since the first one is upside down, it doesn't have any sharp edges to cut the liner. You can arrange the total height by the first pot.
Hope it helps!

Thanks!
Don't you think that some kids might topple the pots if they are in an unstable (not fixed/anchored) position? (just asking .... from your experience)
I say this because usually small kids like to touch everything (which is fine)..and usually in nature plants aren't in pots....so from an educational point of view
it might not be so useful to show the plants in pots..just reflecting...
Regards

Absolutely. I have a golden retriever and she likes to sit-swim in the pond 4-6 hours a day. I think adding frogs to the pond was not the wisest decision I have made. She knocks down every unstable pot. That's why I use heavy and unglazed ceramic pots. Glazed pots are way expensive for a "dog-pond". If that is not enough, I put heavy stones in the bottom of the top pot. It works mostly, but she is a dog chasing frogs.
Another idea might be using larger plastic pots. Generally aquatic plants don't have deep roots and thus the bottom layers are usually filled with gravel. The weight of the stones will keep the pots from moving. One option might be 55 gallon drum barrel. You can cut each barrel into two, or any height you want. Alternatively, if you are considering to include an aquaponic demonstration, those barrels might be a good option. There are many youtube videos on the subject.
Have fun with the design and keep us updated!
edited: spell check