2012 Cherry Street Silva Cell: Urban Tree Canopy Sustainability and Stormwater Reduction Project (Under Construction May 2013)
Maintaining and increasing the urban tree canopy is an important part of reducing stormwater runoff in the City of Burlington as trees intercept rainfall within their canopy and allow the water to evaporate back into the atmosphere rather than reaching our drainage systems. Additionally, tree planting beds that are designed to provide the tree with sufficient un-compacted soil volume (and thereby encourage large, healthy canopies) can also be used to soak up stormwater. The water is available for irrigation of the tree which, in return, will pull the water into its roots and evapotranspirate it back to the atmosphere. Excess amounts of water are filtered through the soil media and returned slowly back to the drainage system. It is the perfect partnership!
The challenge hinges on providing the tree with the necessary uncompacted soil volume in a highly urbanized environment where the soil is compacted due to the need for pavement systems that can support traffic,. However, some technologies have emerged which can provide the structural support necessary for the urban environment while maintaining uncompacted soils for the tree and for stormwater storage and filtration.
The Burlington Stormwater Program and the Department of Parks are working together to install a tree based stormwater system on Upper Cherry Street using Silva Cell technology. This modular frame/deck system supports the pavement systems and allows utilities to pass through the soil and frame structure.
The total cost is approximately $40K, and is funded through the Burlington Stormwater Management Program (supported by Stormwater User Fees) and a 319 Grant through the VT Dept. of Environmental Conservation ($26K).
2011-2013 Stormwater Infrastructure Mapping Update Project Work continues on the infrastructure mapping update project . As of the end of 2012, locations of all known manholes, catch basins, water valves and hydrants have been collected. See here for an example of what the draft data looks like. Additionally, elevation measurements of manholes in the Englesby Watershed have been collected for future modeling purposes.
We are currently working to resolve discrepancies in the area of the City with trickier mapping. Discrepancy resolution is a common step in these types of updates as there are places where it is not clear how infrastructure flows or is connected.
We have also set up a database associated with our GIS mapped features where inspection information collected for our infrastructure can be tracked through time. This is a very exciting component of the project as it will allow us to better prioritize our maintenance activities.
As part this project, several divisions within the Department of Public Works, along with the Department of Parks & Recreation pooled funding to acquire a highly accurate GPS unit so that we can continue to collect additional points that were not located during this update and can collect new points as they are added (new manholes, hydrants etc).
This project is made possible, in part, due to a grant from the Vermont Agency of Transportation which reimburses the City for 80% of its costs, up to $80K.
2011 - 2012 Blanchard Beach Wetland Restoration and Water Quality Improvement Project (Completed)
This project goals were to evaluate the sources of pollutants in the watershed for the small "Oakledge" tributary that drains to the south section of Blanchard Beach (map), to restore the small wetland that is at the mouth of the tributary's outfall, and to make overall water quality improvements which improve water quality in the wetland area and at Blanchard Beach.
Based on the feasibility study, City staff and our consultants, Lakeside Environmental Group, selected a number of water quality improvements and developed a restoration plan for a section of the wetland. The water quality improvements involve the stabilization of the eroding swale along the east side of the Oakledge entrance, the installation of a swirl separator, which will remove sediment and other sediment bound pollutants (oils, bacteria, nutrients) from the runoff coming from the paved surfaces in Oakledge and for much of the lower section of Flynn Avenue. Portions of the wetland were restored by removing some of the accumulated material that has been deposited over the years and creating small micro-pools with wetland plantings (see Blanchard Beach Project Plans). Like natural wetlands, we anticipate that this restored wetland will have increased water quality mitigation functions compared to the degraded system that currently exists, further improving the water quality at Blanchard Beach.
This project was constructed in Fall of 2012. Please click here for the final report and other documents.
This project was funded, in part, by grants from the Lake Champlain Basin Program ($25K) and VT Dept. of Environmental Conservation Ecosystem Restoration Program ($45K). Its total cost, including design, materials, construction and construction oversight was $142K.