Planning for green infrastructure (GI) frequently presents unique challenges and constraints, yet it can often open the door to exciting design opportunities. In many cases, GI takes on the aesthetic of a natural place and therefore can be designed to integrate with the other natural public open spaces in our communities. It also provides a dynamic space in its topography and hydrology, and its usefulness can be highlighted, celebrated, and creatively integrated within the landscape.

The integration of GI facilities can bring new funding sources to communities that may not have the budgets for new open space creation. These new "green" stormwater facilities, diverging from the traditional model of far-reaching collection systems and centralized downstream treatment facilities, are de-centralized in nature and positioned directly within the communities that they serve.


Project Clean Lake Green
Infrastructure Plan
In 2011, the Northeast Ohio Regional Sewer District (NEORSD) entered a consent decree with the U.S. EPA, Ohio EPA, and the Department of Justice to implement a 25-year, long-term control plan to reduce combined sewer overflow (CSO) events to Lake Erie and its tributaries.

To meet the goals of this plan, four billion gallons of CSO volume will be removed annually through grey infrastructure improvements. Furthermore, a green infrastructure plan was implemented to remove an additional 44 million gallons of CSO volume annually. This GI plan was a part of the East 140th Street Consolidation and Relief Sewer project (E140CRS) and Union/Buckeye Green Infrastructure (UBGI) project in Cleveland, Ohio. The architecture firm CDM Smith was selected as the design team.

Challenges and Opportunities

 
A common challenge when designing GI for an owner that is outfitted mainly for maintaining grey infrastructure is accommodating new operations and maintenance regimes in a way that does not add unnecessary complexity. For this project, the decision was made to plant basin slopes and floors entirely with custom, native wetland and upland seed mixes. These mixes deliver a diverse, self-organizing, and cost-effective planting scheme that can be maintained with bi-annual mowing and weeding maintenance routines. This provides an approachable maintenance process, reduces wear and tear on the facility, and reduces overall exposure for maintenance crews.

East 140th Street Consolidation
and Relief Sewer
This project consisted of large, tunneled consolidation sewers as well as three dispersed bioretention basin sites intercepting newly separated storm sewers from a 223-acre portion of a larger 1,930-acre separated sewershed. The combined basin sites are designed to capture 48.3 million gallons of stormwater annually. The basins were constructed on previously vacant properties in relatively flat locations. Strategically situated along the route of a newly proposed separated storm sewer system, they utilize this sewer to convey large quantities of stormwater to each of the three basins.

With relatively high-volume requirements and lower floor elevations due to storm sewer invert depths, these basins required a deeper profile to maximize storage volumes. Picket style fencing, cantilevered sliding gates, and retractable bollards restrict vehicular access to the site and pedestrian access to the basin depression itself.

Opportunities to integrate site amenities presented themselves in the peripheral space surrounding these basins and are community-specific where possible. All sites include new accessible loop pathways, sidewalks, and access points within the right of way. Other common features include open passive lawn space, picnic seating areas, and park bench seating ideally located at viewpoints throughout.

Union/Buckeye Green Infrastructure
This project encompasses one bioretention basin site, four interconnected bioretention basin sites, and one subsurface storage facility. Preliminary design presented challenges to implementing large-scale separated storm sewer redirection to these facilities in a cost-effective way, but an alternative analysis presented an option for utilizing overland flow collection and limited storm sewer redirection to achieve eight million gallons of annual stormwater detention and discharge back to the combined sewer at a controlled release rate to reduce peak flows.

The Union/Buckeye Green Infrastructure basins' properties are situated within a high profile and heavily trafficked location. With relatively low stormwater volume requirements and challenging topography, these basins took on a shallow, interconnected, cascading profile that required maximizing the usable space within their lots and relegated community improvements mainly to the right-of-way. Due to the shallow ponding depths and reduced risk to the public, the team decided against fencing for these facilities, greatly changing the aesthetic.

Site amenity opportunities include greatly improved and new accessible sidewalks within the right-of-way, open passive recreation space, park bench seating throughout, a bicycle pull-off area and connection to Union Avenue with bike racks and picnic-style seating. A triangular site known as "Gateway" was selected for its existing suitability to install a deep subsurface storage and infiltration system in the excavated shale geology. The system maximized stormwater storage volume on this relatively small parcel and transformed the surface of the site into an inviting, highly visible community gathering place.

Open-space programming of the site included an outdoor seating area, a custom exposed aggregate plaza space with undulating seat walls situated above the subsurface storage unit, a ribbon of buffer/shade plantings running throughout the site, and an on-site rain garden to treat stormwater runoff from new impervious areas.

Community Involvement
It was during design of the Buckeye facilities, and specifically the Gateway site, that the opportunity to work with local fabricators and poets presented itself. Concrete curbs, seat wall caps, and sculpture pads were, with the help of a local precast concrete manufacturer, inlaid with cast poetry inscriptions.

A local artist and metal fabricator developed sculptural elements, including a water tower and splash-themed bicycle rack. Custom water drop grates with "Buckeye" inscriptions were fabricated for all trench drain inlets on the cascading upstream basins. The end result is an incredibly personal touch to these sites, adding proud ownership to the space, inspired by and representing members of the local community.

The Upshots
With an emphasis on community co-benefits and inclusion, these facilities work to balance the needs of a complex new generation of stormwater collection and treatment networks with investment toward improved quality of life and opportunity for historically economically challenged communities.

Intense collaboration between the interdisciplinary CDM Smith design team, the NEORSD, contractors, and local artists resulted in stormwater facilities that have become a catalyst for community revitalization with a special emphasis on connection, recreation, and shared space.