Green alley reconstruction focuses on reducing the volume of stormwater in the watershed. Traditional concrete, asphalt and packed gravel surfaces used to construct driveways, alleys and sidewalks are impervious. An impervious surface does not allow stormwater to soak into the ground. Instead, these types of surfaces create run-off that can exceed the capacity of the storm sewer system contributing to flooding during major rain events.
To reduce the amount of impervious surfaces, approximately 240 alleys in the watershed will be converted to green alleys. Twenty-three alleys were completed in 2014, 28 alleys were completed in 2015, and 21 alleys were completed in 2016. One alley will be converted in 2017. The remaining alleys in the Bee Branch Watershed are scheduled to be reconstructed between 2024 and 2038. This conversion is expected to reduce stormwater runoff within the Bee Branch Watershed by up to 80 percent.
How Does It Work? Green alleys feature permeable pavement. Permeable pavement has pores or openings that allow water to pass through the surface and filter gradually into the soil below. It comes in the form of permeable asphalt, permeable concrete, and permeable pavers. For this project, specially designed interlocking concrete pavers will be utilized. In short, the volume of runoff will be reduced by allowing stormwater to soak into the ground. The alleys are “pitched” or graded so that stormwater that does not pass through the surface will run to the center of the alley, flow to the street, and then into the storm sewer system.
More About Green Alleys In addition to reducing stormwater run-off, permeable pavement surfaces replenish ground water and help prevent pollutants on roadways from running off into the storm sewer system and ultimately to our rivers. Green alleys are being used successfully throughout the country and were tested in several downtown Dubuque locations before being selected for the Bee Branch Watershed Project. Other communities using permeable surfaces to address stormwater management include: Charles City and West Union, Iowa; Chicago, Ill.; St. Louis, Mo.; Seattle, Wash.; and Portland, Ore.
Green Alley FAQs Click here for answers to frequently asked questions such as how long will construction last, where can I park, where will trash and recycling be picked up, what will happen to my landscaping and flowers, and what type of maintenance will the City provide in the future.
Interactive Story Map
Click the image below to view the story map.
The interactive story map pictured above features side-by-side before and after photos of the reconstructed green alleys.
Green Alley List and Map
• Green Alley List(To search this document for your street name, press Ctrl F and use the search function in the top right corner of your computer screen.) • Green Alley Map (All 240 alley locations)
Cost The conversion of approximately 240 green alleys is expected to cost $57.4 million. As with most projects funded in part by state and federal programs, a “local match” is provided. In this case, Dubuque’s local match includes stormwater utility funds and special assessments to property owners.
The City of Dubuque does not plow alleys including the new permeable green alleys that have been reconstructed as part of the Bee Branch Watershed Flood Mitigation Project. Snow removal is the responsibility of the abutting property owners.
Snow removal for green alleys is the same as conventional pavement including shoveling, snow blowing, and plowing. Plow blades do not require rubber tips or rollers. Sand should not be applied to the green alleys because it will compromise the permeable nature of the surface. To improve long-term durability we also ask that you minimize your use of salt. New concrete is very susceptible to the harmful effects of salt. If using salt becomes necessary, sweep the slush and salt off the concrete as soon as possible and rinse the concrete in the spring.
If while removing snow from the alley a paver becomes dislodged or damaged, the person removing the snow is not liable for the costs associated with repairing or replacing the paver. The City asks that you report any damaged pavers to the Public Works Department by calling (563) 589-4250.
If you have questions, please call (563) 690-6068. Thank you!