Shade trees grow best in boulevards at least 8 feet wide where there is adequate soil volume. In boulevards that have less than 8 feet of width, there is not enough soil volume to support a healthy mature tree. Tree roots continue to grow beyond the small space and push into adjacent sidewalks, curbs, sewer and water lines. Unfortunately, very few streets in South St. Paul have boulevards that are at least 8 feet wide. Most of South St. Paul’s boulevards are 7 feet or less in width and many boulevards are only 3 feet in width.
Boulevard trees are an important part of South St. Paul’s community character and the City’s 2040 Comprehensive Plan calls for trees along all residential streets where boulevard widths allow. Based on tree root research, there are several small and medium tree species that grow well in a boulevard as narrow as 5 feet. Unfortunately, these trees need more soil volume than a 3- or 4-foot boulevard can provide over their life span. There simply is not enough room for their root systems, and there will be conflicts with infrastructure.
As trees grow and their root systems expand, the City’s curb and gutter, sidewalk, and underground utilities are damaged, and tree root systems are damaged in the process of repairing them, making the trees more susceptible to being tipped over by wind. The City is required to ensure sidewalks are accessible to all users and estimates approximately $1,000,000 in infrastructure improvements are needed due to existing tree root conflict in boulevards less than 5 feet.