The Midtown Alliance (www.midtownatl.com) and TSW (www.tsw-design.com) will soon begin a test program at the intersection of 5^th Street and Juniper Street to determine if an innovative and sustainable stormwater runoff solution will help alleviate stress on the city’s combined sewer system, while beautifying the neighborhood at the same time.  TSW, an Atlanta-based planning, landscape architecture and architecture firm, has designed two bioswales featuring large basins that capture the first flush of stormwater off the street and sidewalk and treat it naturally with soil, vegetation, and microbes before the water is absorbed into the ground. This design and process will reduce the amount of stormwater entering the city’s combined sewer system and increase groundwater recharge.

“To anyone passing by, the bioswales will look like large, beautiful planters,” said Adam Williamson, TSW principal.  “They were installed by Chattahoochee Group, Inc. as the first phase of an overall improvement and transportation project for Juniper Street.  The bioswales were built out of granite to complement neighboring building facades and streetscape elements, and were planted with native plants adaptive to pollution and wet soils.  TSW also proposed river rock mulch to keep the plants stabilized and attractive.”

TSW has successfully created bioswales in more open areas such as parks and other greenspaces, but this is the first time the firm has designed them for a high-density urban setting.  Williamson says he believes these will be the first urban bioswales in Georgia, so the testing period should be of great interest to city planners.

“The Midtown Alliance is focused on finding innovative, environmentally sustainable solutions to urban issues like stormwater runoff,” said Cladie Washburn, director of capital projects for the Midtown Alliance.  “Especially during heavy rainstorms, the amount of water coming off roofs and streets can overwhelm the combined sewer system and stress the Chattahoochee River, where all of this water eventually ends up.  We are optimistic that bioswales can clean and return some of this water safely back to the soil, and keep it out of the drains.  We hope the testing will demonstrate that they offer an attractive and environmentally-safe solution to the problem,” she said.

“The testing should begin in a few weeks and will be conducted by United Consulting,” said Williamson.  “For the next several months, we’ll study the system to determine the infiltration rate and amount of pollutants that can be removed, and make tweaks to the bioswales, if needed.  We’ll also evaluate the permeable mix of soil and sand, and monitor the plants to be sure they can handle the water moving through the bioswales.  One of the bioswales has an overflow drain built in to the structure, while the other does not.  Based on how well each performs during times of heavy rain, future bioswales may or may not incorporate overflow drains.”

Design and installation of the bioswales is part of a broader project to improve the sidewalk conditions and bicycle facilities as well as the overall environmental function of Juniper Street.  The Midtown Alliance retained TSW to design streetscape improvements on the Juniper Street corridor from 14^th Street to Ponce de Leon Avenue.  The TSW team’s design incorporates a buffered bike lane connected to the City’s existing system to provide alternative transportation and recreation options.  On-street parallel parking will be realigned and no longer restricted to off-peak times, and new trees and more spacious sidewalks will be added.  Additional planters, bike racks and trash and recycling receptacles will tie the street together visually and make it more appealing for all users.  Traffic calming efforts, new signalization and crosswalks will improve safety for pedestrians, cyclists and drivers.  The entire project is expected to be completed by the end of 2017.