Northbrook Sewer Project

5-19-2020 new SSO signNorthbrook Sewer Project

The sanitary sewer system in the southern portion of Worthington experiences overflows during heavy rain events. The sanitary sewer overflows result in raw sewage overflowing into residential backyards, public parklands, and neighborhood sidewalks and roadways. These sewage overflows ultimately enter Rush Run and the Olentangy River.  In an average year, this sewer shed experiences 7.6 sanitary sewer overflows and 3.6 water in basement events.

The Northbrook Sewer Project was recommended in the Southeast Sewer Shed Study and Master Plan (Study) as the second of three projects recommended to address overflows and water in basements (sewer backups inside buildings) in this sewer shed. 

The first project has already been completed to the west of this project.  The third project is needed to the east and north and cannot be completed until the Northbrook project is completed.  

Background

The City has studied the southeast sewer shed to understand the dynamics of the sewer system and identify improvements that can be made to reduce the likelihood of sewer overflows.  This study was conducted in compliance with orders from the Ohio Environmental Protection Agency (EPA).  

The Study identified several infrastructure projects to be completed, including the replacement of the Northbrook Sanitary Sewer.  This section of the sewer runs from a manhole just northeast of the intersection of Selby Boulevard and Northbrook Drive East to a manhole just east of High Street.  

  • Constructed in 1920
  • The Study determined the peak flow exceeds the existing capacity in the system by 135%.  
  • The existing pipe is 12 inches in diameter, and it needs to be upsized to an 18-inch sewer.
  • The replacement with a larger line is critical to reducing overflows in this section of the sewer shed as well as upstream.   
  • The need for the greater capacity is due to existing buildings (homes and businesses) along the line.
Southeast Sewershed Capacity Improvements

Selected Alignment

The problem with the sewer has been extensively studied by City staff and third-party experts in sewer operation and design who recommended the installation of a larger capacity sewer line in essentially the same alignment as the existing sewer line.  The existing alignment has numerous benefits.  

  • It fits within the overall sewer system and can be connected to existing service laterals without the need for property owners to install new service laterals in their front yards.
  • It flows by gravity, avoiding the need to site and forever maintain a sewer pump station.
  • It minimizes impacts to property owners since the sewer line goes where an existing sewer is already located.  
  • Finally, it complies with modern design standards for sewers, reducing overflows and backups, thus meeting the mandate from the Ohio EPA.

Other alignments were considered for the replacement sewer.  The city and its design engineers considered other alignments that would modify the existing route, including ones that move the sewer alignment to public right of way.  The other routes were deemed to have technical challenges which made them infeasible. Problems such as: 

  • not enough land cover (the sewer would be above ground)
  • inability to flow by gravity
  • insufficient capacity to prevent overflows and backups 
Northbrook Sewer - Proposed Phase II

Modifications to the existing alignment that could reduce impacts to property owners or benefit the public sewer project were incorporated.  These included movement of the sewer line away from an existing building that is near the current sewer line and realignment from one location to another on the same property at the request of a property owner. This adjustment met the engineering needs of the project and was facilitated by the property owner’s dedication of the easement needed for the new alignment.

Environmental Impacts

Olentangy RiverThe primary purpose of the project is to mitigate negative environmental impacts that are currently occurring – raw sewage in backyards, basements, public parks and walkways.

The project intends to utilize boring (tunneling), if possible, beneath an existing wetland along the project route to mitigate impacts to the wetland.  A loss of trees will occur, however the impact to trees was considered when finalizing the alignment.  Some alternatives evaluated had greater tree impacts.  The City’s project plans have been approved by the Ohio EPA for compliance with all applicable environmental protection standards.

Status

The City has obtained all but one of the easements needed to complete the project.   The City has been in discussions with the property owner regarding the remaining easement that is needed.  After several years of unproductive discussions with the property owner, the City filed to acquire the property by eminent domain and is moving through the legal process to do so.  Once the remaining easement is acquired, the City will finalize the design and move toward construction.  The City will communicate with neighbors and the broader community regarding the details of the construction project as the timeline for construction nears.