City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/30662
the combined sewer system. This third solution is the most environmentally sustainable because it improves water quality and does not have as many long term operational costs. Bioswales are part of Milwaukee’s Green Built Environment Roadway projects. Photo by Scott Baran CPB is caretaker of 5,000 acres of park forests and 85,000 street trees. In 2010, the CPB formed two key partnerships; the agreement with MSD, and secondly, a partnership with the State of Ohio Department of Natural Resources and Hamilton County, to leverage a U.S. Forest Service Grant that funded an urban tree canopy study. The study used high resolution imagery to generate geographic information system (GIS) layers for tree canopy and impervious services, and a CITYgreen analysis measured the benefits provided by our forest canopy for all trees in the urban forest and within parks larger than 20 acres (8 ha). The study found that the overall city canopy has increased over the past decade from 37% to 38.8% and that the urban forest annually abates a volume of stormwater that would require 108,700,000 cubic feet of infrastructure to store and manage and that would cost $28,450,000 annually over a 20-year period to construct. The tree canopy and impervious surface data produced by the study was captured at a 6-inch (15-cm) resolution and its quality is far superior to the imagery used ten years ago. The high quality data allows more accurate modeling and evaluation of best management practices for storm- water control. In Milwaukee, Wisconsin, runoff from the roadway enters the bio- swales through curb cuts and filtrates through two layers of engi- neered soil and crushed stone. Photo by Scott Baran In 2010, the Cincinnati Park Board (CPB) signed a memorandum of understanding with the Cincinnati Metropolitan Sewer District (MSD) to help design, install, and maintain stormwater source control measures using green infrastructure in various key watersheds in Cincinnati. MSD has a consent decree to remove 2 billion gallons of stormwater from the combined sewer overflows (CSO) in the Lower Mill Creek in Cincinnati by 2018. There are three strategies in handling the CSO prob- lem in Cincinnati, which rates in the top five worst cit- ies in the country in overflow events. One is a “gray” solution to build a 1.5 mile (2.4 km), 30-foot (9.1 m) diameter concrete tunnel to hold the excess water. Another is to build more and bigger underground pipes to convey all the storm water. The third is to find green solutions to absorb or slow water before it reaches www.urban-forestry.com Most cities are limited to planting trees in rights-of-way and parks. The partnership with MSD has allowed the CPB to look at many more opportunities for reforesta- tion. Because the MSD has an obligation to reduce source runoff, it has the ability to commit both capital and operational funds to meet the short and long term goals. The CPB is using aerial photography and GIS data to explore reforestation opportunities on surplus city lots and private property to achieve the synergistic goals of beautification, increased tree canopy and associated environmental benefits, and stormwater reduction on blighted urban vacant lots. CPB staff, contractors, and volunteers work together to clear invasive honeysuckle, remove trash, and plant thousands of native tree seed- lings that will serve to improve forest quality and absorb and slow down rainwater. Trees and landscaping can also be incorporated into construction of best management practices. In 2010 the CPB completed two bioinfiltration projects on private property. The largest is the St. Francis Court Apartments property, an assisted-living apart- ment complex. Two large parking lots were removed from a hillside setting and replaced with two 3,800 square foot (353 sq m) bio-infiltration gardens. This serves to absorb and hold water draining from the 35