B&N is helping the City of Columbus, Ohio, take a new, greener approach to remedy sanitary sewer overflows (SSOs) caused by inflow and infiltration (I/I) from stormwater runoff from private sources, such as roof runoff and sewer laterals.
To lessen the impact of SSOs on the environment, the City is operating under directives from the Ohio EPA using a multi-step approach to address the SSOs. Blueprint Columbus is the City’s pilot program to reduce SSOs and is founded on four pillars: lateral lining, roof water redirection, sump pumps and Green Infrastructure (GI).
GI helps manage stormwater runoff so that it doesn’t flow into the sanitary sewer. SSOs can cause raw sewage to back up into a home or a water supply, threatening private property and causing public health concerns. B&N is leading a Blueprint Columbus project in the Grandview Heights neighborhood to evaluate, develop, design and implement GI solutions to prevent SSOs.
Using a PCSWMM model for a hydrologic and hydraulic (H&H) model of the study area, B&N determined the total suspended solids (TSS), nutrient treatment performance and GI alternatives. Based on these findings, B&N designed bio-basins, also known as rain gardens, within the neighborhood right-of-way between the curb and property boundary or sidewalk.
Openings in the roadway curb route the stormwater runoff into the bio-basins, which filter the runoff through a top layer of permeable, engineered soil, plants and gravel. These features filter certain pollutants before the stormwater reaches the sewer, such as roadway grime, grit, metals or trash, improving the quality of stormwater being discharged into streams.
Bio-basins also provide additional storage for the stormwater runoff. An underdrain at the bottom routes the runoff to the storm sewer. This controls the quantity of water going into the storm sewer, reducing the likelihood of overflow.
Key features of the Blueprint Columbus project include: