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  • Green infrastructure - combating climate change one project at a time

    May 17, 2019 | Read More News
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    File: Shannon Gardens Green Infrastructure ProjectA dash of green will return to former farmland as part of a Pima County collaboration designed to meet the challenge of climate change.

    Experts from six County agencies - Community Development and Neighborhood Conservation, Environmental Quality, Flood Control, Natural Resources, Parks and Recreation, Sustainability and Conservation, and Transportation - teamed with Watershed Management Group on Shannon Gardens, a new Green Infrastructure project in Flowing Wells.

    Named for the Shannon Gardens neighborhood just to the east, the project sits on what once was the farm of Gene Shannon, who grew corn and alfalfa on 360 acres south of Rillito Creek. After development overtook agriculture in the area, the County acquired the parcel as right-of-way for Shannon Road between Palmyra and Sahara Streets. Except for gravel covering the first few feet of the shoulder, the once-fertile soil was a barren strip of compacted, nearly impermeable dirt that contributed to localized flooding.

    WMG designed the layout of channels, basins and berms and selected the locations for the plants: 58 trees, 150 cacti and other succulents and dozens of stands of grasses and shrubs from the Pima County Native Plant Nursery.

    "Ideally, what we do is we get the community really involved and excited about projects like this, and try to get volunteers who will come out almost weekly and pick up trash and pull buffelgrass and other invasive species. We want them to be invested in it," WMG River Restoration Biologist Trevor Hare, the project manager said.

    The design also calls for covered curb cuts and other features that will channel the water off the roadway and into the project's retention basins.

    Neighbors welcome the work. Before, water would form massive pools in many yards and driveways that would persist for days, allowing mosquitoes and other pests to proliferate. Keith Clark, who lives next to the job site, served as an unofficial night watchman for project.

    File: Shannon Gardens Green Infrastructure Project"I've been here since 1984. Water didn't have anywhere to go. When it rained good, there would be a massive puddle, 18-inches deep, across the road," Clark said. "I love this. When the trees come in, it will make my house a whole lot cooler."

    Shannon Gardens is one of 43 current projects identified as part of the County's Green Infrastructure Action Plan which involved input from ten Pima County departments and experts from other local governments, non-profit groups and consultants. It builds on existing County efforts to restore riparian areas and watersheds. Marie Light, Environmental Quality's Principal Hydrologist, oversees the County's Green Infrastructure Program.

    "The goal of green infrastructure is to keep water higher in the watershed for a longer period of time," Light said. "Development has meant that we've taken out needed vegetation and replaced it with 'hardscape' - buildings and driveways and roads - so now half of a given area sheds any rainfall immediately. Where once it could fall and soak into the ground and plants could use it or it would go into the water table, now it just runs downstream and creates more serious flooding downstream."

    Project planners vetted sites using the Flood Control District's Autocase modeling software, which compared the green infrastructure design to a “do nothing” scenario. Major criteria included a lack of existing vegetation, relatively high surface temperatures, the potential for flooding and the socio-economics of the neighborhood and the potential increase in property values. The Shannon Gardens neighborhood scored high in those last two categories. A high number of relatively small, individually-owned lots there marked it as a location with an above-average number of homeowners who would benefit from the improvements.

    "With lots of useful data from the County and the Pima Association of Governments, it became pretty easy to identify our location," Community Development and Neighborhood Conservation Community Planner Ryan Stephenson said. “The more criteria that is included in identifying an appropriate project, the narrower the opportunities.”

    Green infrastructure brings a host of benefits. By using an array of products, technologies, and practices, GI projects use natural or engineered systems that mimic natural processes to slow stormwater runoff, protects people and property and allow more of the region's most valuable resource to recharge local aquifers. It also creates wildlife habitat, shades and cools streets and buildings, reduces air and noise pollution and encourages residents to get outdoors and engage in physical activity.

    It helps Pima County's bottom line too. Moody's Investors Service, a leading provider of bond credit ratings, now considers exposure to climate risk when evaluating municipalities' creditworthiness. 

    The overall objective is to complete all 43 projects by 2025, to meet the goals of the Paris Agreement as mandated by a pair of Climate Change resolutions passed by the Board of Supervisors in 2017 that require the County implement the new Sustainable Action Plan for Pima County Operations to reduce greenhouse gas emissions by 40 to 42 percent below current levels and undertake key climate adaptation efforts like green infrastructure. Climate Science makes plain the urgency of the Green Infrastructure Action Plan. By some predictions, surface temperatures in the southwestern United States could rise by another 11 to 16 degrees Fahrenheit by 2050 in urban areas. At the same time, climatologist expect less winter rainfall and increased flooding from more extreme summer storms.

    File: Shannon Gardens Green Infrastructure Project"I'm very concerned about climate change and the effect it will have here," Light said. "What does that mean for people who can't drive, for people have to ride a bicycle or take the bus when it's 120 degrees out? How do you do grocery shopping, how do you get exercise? What if we have a widespread power outage in the middle of the summer? More green infrastructure cools things down and will help the community endure."

    WMG, for now, will focus on helping the plants from the first phase of Shannon Gardens establish themselves with weekly watering and site maintenance. Hare plans to wait until summer to begin work in the remaining sections, using the Monsoon to give those plants a boost. WMG will continue to cover maintenance of the Shannon Gardens green space for several years under terms of its contract with Community Development and Neighborhood Conservation.

    High-priority green infrastructure projects in the works include building water harvesting features at White Elementary and Pistor Middle Schools, adding irrigation and water harvesting along sections of the Chuck Huckelberry Loop's Santa Cruz River Park, and planting trees and replacing concrete with more porous material at the Kino Service Center. If all goes to plan, the Green Infrastructure Program will plant 4,684 trees around 27 public buildings, 101 parks, 3,061 rights-of-way and 235 other sites countywide.