"We harvest over 30,000 gallons (114,000 liters) of roof runoff in tree basins to passively shade & cool the building from which we harvest the water.
This was created in 1996 by 2 people in 2 hours, only using hand shovels. We worked in the rain, because that is the funnest time & you get instant feedback from the water flow. No materials were purchased, imported, or exported—we just used what was freely available on site.
Every year we maintain the system by building up the berms, digging the basins deeper (to get the dirt for the berms), or filling in any blow outs in the berm. We do this during or just after a rain when its nice and cool & the soil is soft & workable.
The planting of rain & trees was done in the public right-of-way between the auto parts store/warehouse & the street after we got the permission from the auto parts store manager.
We could have also planted multi-use native understory plants at the same time we planted the trees, as we do in all new installations."
https://www.harvestingrainwater.com/video/harvesting-30000-gallons-of-roof-runoff-in-tree-basins-for-free/