Part II of Low Impact Development Conference presentations on New York City’s Green Infrastructure Maintenance.
Miki Urisaka, New York City Department of Environmental Protection, and Shandor Szalay, AKRF, spoke about how the city is studying green infrastructure operations and maintenance during the Low Impact Development Conference in Portland, Maine, in August.
How do you know that 3,000 distributed green infrastructure stormwater bioswales are functioning as intended? New York City is scaling their green infrastructure program quickly. About 700 bioswales have been built since 2011 with another 2,500 under construction. How can city staff ensure functionality as the city scales up over the next two to three years?
“Assets enter the [maintenance] program after the two-year contractor guarantee period,” Shandor said. A big issue is that contractors don’t maintain the facilities once construction is completed; “they don’t come back.”
The city, working with AKRF is undertaking research to determine how best to deploy staff and resources. Research will take a look at tying maintenance to asset performance. For instance, do clippings from pruning need to be removed or is performance better with higher organic matter? They also want to understand how maintenance influences plant health. Are diverse plantings more resilient to stresses? Among the hypotheses being tested are that weeding doesn’t impact performance and that irrigation isn’t necessary to support plant health. They’ll also be looking at how groundcover affects stormwater retention, infiltration performance and plant health.
In addition to research, the work will quantify information from ride-alongs with staff performing maintenance. Currently, bioswales are visited twice a week by city parks workers, which may not be sustainable in the long run. Maintenance is primarily driven by trash build up. Routine maintenance also includes sediment removal, weeding, replanting, pruning and watering as needed. Part of the answer going forward is to provide latitude to field staff within standard operating procedures, while at the same time being cognizant of cost and optimum level of maintenance service.
Demonstrating to city employees there’s an opportunity to advance is important. For instance, creating a career path for seasonal Parks Department workers to become gardeners.
Ride-alongs help understanding of field level decision making, while benchmarking will develop time and materials metrics, as well inform a quantitative assessment of the condition of the bioswales. Even though bioswales may be virtually identical, they all look different, Shandor said.
February 15, 2017 NewTerrain