Uploaded March 2015 | Updated September 2026, 2 hours ago

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London Heathrow Airport isn't just planes, runways and duty free, it also has more than 100 hectares of green space, the equivalent of 140 football pitches.

All this land needs to be looked after, and it's not as simple as you'd think, as we discovered when we went to find out about electro-fishing and what happens to the water that runs off the runways.