Westminster Parking Lot Plantings

For those concerned about parking lots contributing to stormwater runoff and the urban heat island effect, the new Westminster Choir College parking lot offers an interesting angle. Three previous posts showing its construction, including underground cisterns to hold back stormwater, can be found by typing "westminster" into the search box of this blog.

In the first photo, water from the pavement flows into a raingarden. Though many of the planting choices make sense, e.g. redbud, tupelo, summersweet and switchgrass), the english ivy in the foreground will likely prove regrettable. My forecast is that it will spread over the curb, making for a messy look, and also spread into the rest of the raingarden, competing with the other species.

This retention basin/raingarden appears to be seeded with a "wetland mix" of sedges and rushes, rather than turfgrass planted on higher ground. The seeds are spread in a liquid mix of cellulose that helps shade the ground and keep it moist while the seed sprouts. Beautiful river birches in the foreground dried up for lack of water, but hopefully will survive.

The berm here, planted with hemlock and other evergreens, is meant to screen the parking lot from the neighbors. The neighbors were very outspoken about having a parking lot replace the field they had long been able to look out upon, and this vegetated buffer was the Choir College's response.

Maples and shrub dogwoods are some other native species used. Unfortunately, seven ash trees were planted as part of the project. They'd be great shade trees for the parking lot, except that the Emerald Ash Borer--an exotic insect introduced from Asia that has been spreading rapidly from Michigan eastward--will likely reach Princeton in a few years. When it arrives, we can start saying goodbye to all of our native ash trees, of which there are many thousands in our preserves and along streets. It's a surprise to see landscapers still planting them. Even Princeton University included some in its stream restoration down near Washington Road.

The overall effect of the parking lot on runoff, though, should be neutral, if all the engineers' calculations prove right, and though much of the grassy field was paved, the new plantings may actually provide better habitat than the mowed grass they replace. The project could have used more trees planted near the pavement that could eventually shade most of the asphalt.