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HomeMy Public PortalAboutStormwater Tree Trenches - DPWCity of Watertown, MA  ARPA Project Proposal Submitted by: Gregory St. Louis Submitted on: May 25, 2023 Request Number: ARPA-16 Project Name: Stormwater Tree Trenches Proposal Type: City Department Department of Public Works Recommended Project Manager: Gregory St. Louis Project Summary: This green infrastructure project will support the installation of 50 stormwater tree trenches. The stormwater tree trenches will be designed to reduce and treat stormwater runoff and recharge groundwater.  In Watertown, phosphorus is a pollutant of concern for the Charles River.  By filtering and infiltrating runoff, phosphorus loading to the River will be reduced.  The project will also support the City’s efforts and goals of its Stormwater Management Plan under the Environmental Protection Agency’s Municipal Separate Storm Sewer System permit program.  It will also support the City’s municipal vulnerability program. Green infrastructure mimics natural processes to capture, infiltrate, and treat rainfall and stormwater runoff. Stormwater runoff is rain or snow melt that soaks into the soil and recharges groundwater, naturally drains into waterbodies, or is conveyed through a series of pipes until it is discharged into a nearby waterbody. Stormwater runoff, if not properly treated, can carry pollutants into waterbodies and be harmful to public health and safety. With precipitation events becoming increasingly intense due to climate change, much of the stormwater infrastructure designed decades ago is now undersized, which can also cause stormwater flooding. Flooding can also occur in areas where the City’s stormwater system becomes overwhelmed due to high amounts of impervious surfaces. Through the installation of tree trenches, we will be able to enhance groundwater recharge in highly paved neighborhoods, remove pollutants such as phosphorus before water is discharged into the Charles River, and improve air quality. For example, trees absorb pollutants such as nitrogen dioxide and sulfur dioxide and produce oxygen. Trees also absorb carbon dioxide, helping to sequester climate-warming pollutants and lessen Watertown’s contribution to global climate change. Amount of ARPA Funds Requested: $1,000,000 Minimum Funds Needed: $500,000 Matching funds available? Don't Know Other funds available? Don't Know Project Narrative: I will use the form to enter narrative Narrative description of the project: This green infrastructure project will support the installation of 25 stormwater tree trenches. The stormwater tree trenches will be designed to reduce and treat stormwater runoff and recharge groundwater. In Watertown, phosphorus is a pollutant of concern for the Charles River. By filtering and infiltrating runoff, phosphorus loading to the river will be reduced. The project will also support the City’s efforts and goals of its Stormwater Management Plan under the Environmental Protection Agency’s Municipal Separate Storm Sewer System permit program. It will also support the City’s municipal vulnerability program. Detailed Project Budget: The total cost per unit is $20,000. This will cover all the costs related to excavation, installation of a crushed stone base, perforating the pipe, back filling, connection to either the existing or a new catch basin, and loam and seed for each unit. Timeline for the project: Design Completed - December 2023 Construction Start - April 2024 Construction Completed - December 2024 Resources required in addition to the ARPA funding: N/A Metrics for success of the project: Reduction in flooding Reduced phosphorus levels Improved air quality Outputs / outcomes: Reduction in flooding Reduced phosphorus levels Improved air quality Increased tree plantings What will be the overall benefit? With precipitation events becoming increasingly intense due to climate change, much of the stormwater infrastructure designed decades ago is now undersized, which can also cause stormwater flooding. Flooding can also occur in areas where the City’s stormwater system becomes overwhelmed due to high amounts of impervious surfaces. Through the installation of tree trenches, we will be able to enhance groundwater recharge in highly paved neighborhoods, remove pollutants such as phosphorus before water is discharged into the Charles River, and improve air quality. For example, trees absorb pollutants such as nitrogen dioxide and sulfur dioxide and produce oxygen. Trees also absorb carbon dioxide, helping to sequester climate-warming pollutants and lessen Watertown’s contribution to global climate change. Green infrastructure mimics natural processes to capture, infiltrate, and treat rainfall and stormwater runoff. Stormwater runoff is rain or snow melt that soaks into the soil and recharges groundwater, naturally drains into waterbodies, or is conveyed through a series of pipes until it is discharged into a nearby waterbody. Stormwater runoff, if not properly treated, can carry pollutants into waterbodies and be harmful to public health and safety.