Improvements to Herring Run Interceptor SC No. 856
GMB was retained by the City of Baltimore to to rehabilitate the existing parallel Herring Run Interceptor sanitary sewers and the West Branch Herring Run Interceptor Sewer. As a subconsultant to URS Corporation, GMB provided engineering design services for Sanitary Contract No. 856.
The original Herring Run Interceptor was constructed in the late 1920’s / early 1930’s with a parallel interceptor added in the late 1950’s / early 1960’s. The West Branch Interceptor was constructed in the 1930’s. Much of the length of these interceptors is located in stream valleys making access and maintenance difficult. Due to the age of the pipes and close proximity to streams, the interceptor system experiences infiltration entering the sanitary sewer system at joints and cracks which takes up capacity and increases wastewater treatment costs. In addition to the ever-present infiltration, the system also experiences occasional manhole collapses due to heavy rainfall, causing high stream flows which may damage manholes, thus allowing stream water to enter the system.
SC 856 consisted of rehabilitating approximately 28,500 LF of existing sewers ranging in size from 18” to 33” diameter gravity interceptor using Cured-In-Place Pipe (CIPP) lining, and rehabilitating approximately 125 existing manholes using a resin-based liner. Both products provide a water-tight seal to prevent infiltration from entering the system and provide structural strength enabling the system to withstand the additional structural stresses caused by high stream flows. To further prevent extraneous flows from entering the system, SC 856 also provided water-tight manhole frames and covers to all manholes.
In addition to the sanitary sewer and manhole rehabilitation, the project also includes geomorphic improvements to a section of the West Branch Herring Run stream to protect a section of exposed sewer from further erosion. Maintenance of traffic along Perring Parkway and significant reforestation to offset the trees removed for access were additional design features.