clipped from: news.com.com 
Also part of Olympic Forest Park will be this porous concrete, which allows water to percolate through instead of running off. This way, the ground can stay moist, and requires less watering. Some Olympic athletic events, including tennis, archery and hockey, are expected to take place in the massive park.
The Olympic park is supposed to be a model for the sustainable city and water management. It's due to be completed next year.
Credit: Michael Kanellos/CNET News.com