PWD’s Watersheds blog closes out the year with a list of 11 green missions accomplished in 2011, from innovative stormwater management projects and stream restorations to groundbreaking policy agreements and energy-generating solar arrays.

The images above shows the progress of the stormwater tree trenches and stormwater planters near the intersection of Hunting Park and Castor Avenues. The two tree trenches and seven planters are designed to capture up to 40,000 cubic feet of runoff from surrounding streets, or an estimated total drainage area of 40,000 square feet.

Stormwater planters and tree trenches are soil-water-plant systems that intercept runoff, infiltrate a portion of it into the ground, evaporate a portion into the air, and in some cases release a portion of it slowly back into the sewer system. Reducing or slowing the amount of stormwater that enters our sewers helps protect the rivers and streams that supply Philadelphia’s drinking water by preventing combined sewer overflows.