Jill: Can you tell me a little bit about the sustainable features of the High Line and how you tried to work toward designing features for environmental sustainability?
James: This is an extremely hostile and very difficult environment to build a landscape. We have a soil depth that is very thin – maybe 15 inches typically – it’s very hot in the summer, it’s freezing cold in the winter, there are issues with providing plants adequate water and nutrients – it’s a very difficult environment. Most of the plants up on the High Line are stress tolerant. They’ve been drawn from the prairie or from other difficult environments and most of them will hopefully succeed in survival. We’ll learn from those that don’t make it, take them out and replace them with those that have done well. There is also a dynamic aspect to how the landscape is managed. One of the greatest features of the High Line is the paving, which has been designed to crack open and allow plants to come through. It also has open joints so that when it rains the water falls through the joints and is collected, stored and then allowed to seep slowly into the planting beds. I think we can demonstrate that 80 to 90 percent of all the water that falls on the High Line stays on the High Line.
Jill: That’s impressive.
James: One could boast that there’s going to be some carbon reduction with the amount of greenery that we’ve brought there. There’s certainly an ambient cooling effect with the shade that’s provided. All the materials are recyclable or come from sustainable sources, so there’s nothing here that’s ostentatious or out of place. Overall I think it’s a very sustainable project.
Jill: So just to clarify, are you expecting plants to grow up through the cracks at some point?
James: No. It’s really what we call tapers or the combs. There’s an idea of trying to comb the paving so we don’t really have clearly defined edges between path and garden but really that the path bleeds into the garden, and likewise, the garden bleeds into the path. Obviously there are parts where it’s a little harder – for the main pathways, for maintenance, for emergency vehicles and this sort of thing – but the overall visual effect is to try to create an edge to edge effect of a rail bed landscape that has some paving and a lot of planting around the rails. It really is a wall-to-wall landscape rather than the typical garden path adjacent to planting beds.