We have wonderful city dumps in the San Francisco Bay area.
One is now Shoreline Park. Another is Bair Island a little north of Facebook's headquarters by Dumbarton Bridge. Palo Alto's former dump (where I have unloaded cardboard boxes, batteries, old paint ... more times than I can tell) has more recently been turned into Byxbee Park.
A newly converted dump contains methane. Loads of it. Consequently, former dumps can be recognized by the small vent pipes that are spaced out over the area. I am sure that you appreciate that your morning run doesn't have to be in air that smells from cow farts.
When a dump is converted, the trash is packed in clay to control the methane. It is like a baked Alaska, only you really don't want anybody to break through the meringue into the "ice cream" part of the cake.
So what to do if you want this bleak clay cake to turn into a living habitat for wildlife?
Palo Alto called in Daniel McCormick and Mary OBrien from Watershed Sculpture to improve the area with the "slug" - officially called Foraging Islands - depicted with this post.
From the official description: "Foraging Islands will help to re-establish habitat in the Baylands, allow park visitors to learn and appreciate the importance of diverse habitat types, and introduce the idea that wildlife friendly public art can enhance habitats and visitor experiences."
The idea is to create the basis for insects to nest - their young will feed the critters that in turn will feed owls, hawks, and other carnivores. But it all starts with decaying plant material where the beetles, bees, wasps (even termites?) can lay their eggs. More on this work here.
The group of volunteers got their reward when their efforts were being observed by a small burrowing owl - one of the very species for whom the project was undertaken.
You can read much more about Watershed Sculpture's work in this wonderfully illustrated article.