This 2,700 sq. ft. rain garden design with curb cuts along Spring Street was the first of 120 plus parkway rain gardens built in public right-of-ways in Aurora, Illinois. An engineered soil mix (1/3 topsoil, 1/3 compost, and 1/3 sand) was placed above free draining washed gravel used as backfill over new sewer pipes, then planted with a mix of native and horticultural species in a naturalistic arrangement. The rain garden treats the first ???(R)???AE????-inch of runoff from 1.3 acres of adjacent residential street and private property.

Aurora, Illinois (pop. 197,899) is about 42 miles west of Chicago. Aurora's historic nickname, like Paris, is "City of Lights," an official name adopted by Aurora in 1908 to commemorate that in 1881 it became one of the first U.S. cities with all-electric street lighting. The downtown is located on the Fox River, and, like Paris, has a prominent historic island in the river"?uParis has Île de la Cité and Île St. Louis; Aurora has Stolp Island. The city is basically divided into the east/far east (bordering Naperville) and the west side of the river.

Block-long rain gardens constructed in the parkway along East Galena Boulevard complement the entry into McCarty Park. This photo was taken the morning after over two inches of rain fell in Aurora. Sediment deposited by stormwater runoff that accumulates in curb cuts is removed during routine maintenance. Early on, lack of proper maintenance and the engineered soils being too dry for some of the plants was a problem. A new maintenance contract and supplemental plantings of species more suited to the dry conditions resolved those issues. A flow monitor indicates the rain gardens are efficiently infiltrating all of the runoff directed toward them (infiltration rates varied from a low of 6.8 inches per hour to a high of 34.4 inches per hour). Eric Schoeny, PE, drainage and underground coordinator with the city, credits appropriately sized rain gardens to the watershed, and the very permeable sandy-gravelly subsoil below the rain gardens.

In some of the more historic parts of the city the sewer infrastructure dates back to the 1880s. Unlike modern sewers, which separate wastewater and stormwater, these century-old sewers combine sanitary waste with stormwater runoff from streets, rooftops and driveways, sending them both through the same pipes to the Fox Metro Water Reclamation Plant for treatment. Under normal conditions, these vintage combined sewers adequately serve the needs of residents in older parts of Aurora, usually those neighborhoods closest to the Fox River. But during heavy rains the sewers become surcharged. The city averages about 37 inches of rain, and 29 inches of snow. When sanitary wastewater and rainwater exceed the capacity of the pipes, the excess flows into the Fox River, or backs up into basements of homes. As part of their EPA-approved long term control plan (LTCP) for combined sewer overflows (CSOs), Aurora has implemented a system-wide green infrastructure program to infiltrate stormwater runoff whenever possible and keep it out of the combined sewer system. A major component of the green infrastructure program has been construction of rain gardens in the public right-of-way in neighborhoods with combined sewers.

The downtown Downer-Stolp project (on Stolp Island) almost imperceptibly blends green infrastructure into the streetscape. Using the existing downtown plant palette, horticultural varieties such as lantana (an annual in northern Illinois), "Knockout' roses and "Annabelle' hydrangeas were planted in the infiltration beds. Directing runoff into the rain gardens on this urban island setting was more challenging. Engineer Schoeny designed an inverse storm sewer siphon system that allowed traditional inlets along the curb to collect and trap debris and coarse sediment in sumps, while still directing runoff into the rain gardens.

Evolution and Growth of Green Infrastructure and Streetscapes
Aurora's first green infrastructure streetscape project, Spring Street rain gardens, was completed in 2010. This effort involved construction of a nearly one-city block long rain garden in association with a sanitary/storm sewer separation project in a residential neighborhood.

After the combined sewer was replaced with storm and sanitary sewer pipes, Section 319 grant funding from the Illinois EPA and Chicago Metropolitan Agency for Planning (CMAP) went to help design and construct rain gardens. Curb cuts direct flow from the curb line into a series of rain gardens constructed in the parkway between the sidewalk and curb. An engineered soil mix (1/3 topsoil, 1/3 compost, and 1/3 sand) was placed above free draining washed gravel used as backfill over the new sewer pipes. The rain gardens are planted with native and horticultural species in a naturalistic arrangement. The 2,700 square feet of rain gardens fully treat the first ¾-inch of runoff from 1.3 acres of adjacent residential street and private property.

The Downer-Stolp project on Stolp Island also used established downtown hardscape elements: brick soldier courses, historic street lights with hanging baskets, site furnishings and paver crosswalks to further reinforce the sense of place. Carriage walks connect with the sidewalks to keep people parking on the street from trampling through the rain gardens.

The Spring Street rain gardens functioned very well, but there were issues with the plantings. There was little community involvement during project planning, and some local residents were not happy when the turf was replaced with taller plants; some did not appreciate the natural appearance of some of the plants, e.g., Kalm's St. John's wort (a low shrub with bright yellow flowers in small clusters that's considered threatened or endangered in Illinois and Ohio). Ineffective weeding and not mowing of the turf border did not help. Also, the engineered soils were simply too well drained for some of the plants (e.g., the "Obedient' plant) to thrive, leading to the loss of some plants in the first couple years.

McCarty Park Rain Gardens
Aurora received American Recovery and Reinvestment Act (ARRA) funding from the state to construct another one block long rain garden in association with another sanitary/storm sewer separation project. Located only a couple blocks south of Spring Street, the McCarty Park rain gardens, named for the adjacent city park, were completed in 2011. The design closely resembled the Spring Street project, and initially shared some of the same challenges: lack of proper maintenance and the engineered soils being too dry for some of the selected plant materials. However, via a separate natural areas maintenance contract, Aurora found a more knowledgeable maintenance contractor and supplemented the planting with species more suited to the dry conditions. These sites are now looking much better.

Conceptual diagrams and renderings helped explain proposed improvements to east side residents during public meetings. Public understanding of problems associated with combined sewer overflows (CSOs) and how green infrastructure streetscapes could protect water quality in the nearby Fox River and reduce sanitary sewer backups into basements was important in obtaining neighborhood support for the projects.

City engineers fitted a flow monitor to the storm sewer overflow at the downstream end of the McCarty Park rain gardens. No overflow has been detected, indicating the rain gardens are infiltrating all the runoff directed toward them. Eric Schoeny, PE, drainage and underground coordinator with the city of Aurora, credits this to appropriately sizing the rain gardens for the watershed, and the very permeable sandy-gravelly subsoil in the rain gardens.

Performance monitoring of the McCarty Park rain gardens was completed in 2011 with Illinois Sustainable Technology Center and the Fox River Ecosystem Partnership funding. Testing documented high infiltration rates on site, varying from a low of 6.8 inches per hour to a high of 34.4 inches per hour. The variability was consistent with other sites included in the research project, and was thought due to lower infiltration rates found adjacent to structures, such as manholes, and lower infiltration rates near curb cuts where sediments deposit.

An average of three feet of impermeable fill material was removed and replaced with free-draining washed gravel and engineered soil to access sandy/gravelly subsoil as part of the green infrastructure for CSO control projects completed on Aurora's east side.

Downer-Stolp Streetscape
Aurora next started work on a major downtown road and Fox River bridge reconstruction project on Stolp Island. A charrette gave stakeholders the opportunity to offer ideas on how to improve the downtown beyond just the needed road and bridge repairs. The charrette led to the Downer-Stolp streetscape project, funded in part by the Illinois EPA's Illinois Green Infrastructure Grant (IGIG) program, and completed in 2012.

The Downer-Stolp project expanded the downtown streetscape southward, shortened crosswalks, converted Downer Place from one-way to two-way traffic and added rain gardens to infiltrate stormwater runoff in the highly impervious downtown. Aurora's Eric Schoeny designed an inverse storm sewer siphon system, allowing traditional inlets along the curb to collect and trap debris and coarse sediment in sumps, while still directing runoff into rain gardens. Carriage walks keep people from stepping into the gardens.

Precast open-back curb inlets were used to provide a continuous curb line, while still allowing runoff to flow into the rain gardens. Sumps were constructed below the curb inlets to capture coarse sediment and debris, keeping it out of the rain gardens. The sumps will be vacuumed out as part of the city's regular sewer maintenance.

The Downer-Stolp rain gardens needed to complement the traditional streetscape plantings. Massings of single species resulted in a simpler more ordered look. The city's horticulturalist added annuals to help achieve a more formal appearance. A maintenance guide helps the staff and volunteers in caring for the plants. The project has varied paving patterns and materials, plus improved lighting, signage, benches and trash receptacles. Aurora's city hall, only a couple of blocks east of the Downer-Stolp project, was flooded (pun intended!) with compliments.

120+ Rain Gardens
Aurora's ambitious green infrastructure streetscape program has designed and installed over 120 parkway rain gardens in the public right-of-way in primarily residential neighborhoods served by combined sewers on the city's near east and near west sides. This goal was significantly bolstered by a second grant from the state's IGIG program, referred to as Green Infrastructure for CSO (combined sewer overflows) Control. Problems associated with CSOs and the benefits of rain gardens were discussed at public meetings. Residents were invited to vote for different types of vegetation, including trees, shrubs, grasses and perennials. Locations targeted for green infrastructure were primarily intersections with appropriately proportioned contributing watersheds. Curb bump outs were used at intersections to increase the area available to construct rain gardens. The bump outs shortened crosswalks, aided in traffic calming and in meeting accessibility requirements in these mostly residential neighborhoods.

Green infrastructure streetscape improvements included work adjacent to Bardwell Elementary School on Aurora's near east side. Bump outs increased the area available for rain gardens, shortened crosswalks and provided traffic calming near the school. Compacted aggregate backfill was used below sidewalks and curbs, and free draining washed gravel provides a hydrologic connection between the engineered soil and native sandy/gravelly subsoil. Underdrains with cleanouts were installed in case infiltration capacity decreases over time. The underdrains are intentionally blocked and currently not in use.

In fall 2014, most of the 100 plus rain gardens in the public right-or-way on the near east side were constructed. The project locations were either 4-way or 3-way intersections. After completing the curb bump outs, sewer inlets and sidewalk modifications the rain gardens were backfilled with free-draining washed gravel and engineered soil to promote infiltration. Contiguous areas in the parkway were planted in a similar manner as the rain gardens to provide a unified appearance.

Additional Projects Underway
Additional green infrastructure streetscape projects are underway on the west side of Aurora. The first project is construction of parkway rain gardens at an intersection surrounded on all sides by Holy Angels Catholic Church and school property. No bump outs are planned, given the narrow street and existing parking lot driveways. A fall 2015 volunteer planting day is planned after construction is completed. Another project to construct green infrastructure streetscape improvements (intersection curb bump outs and 35 more rain gardens) in neighborhoods on the near-west side is scheduled to be complete in late 2015 or spring 2016.