LCA Sanitary Sewer Manhole Inspection and Rehabilitation

Lehigh County Authority, which obtained a long term lease of the water and sewer systems of the City of Allentown, retained Barry Isett & Associates from 2014 through 2016 to develop a program to inspect and coordinate the rehabilitation of manholes within the City of Allentown’s wastewater system. The manholes were determined by members of Lehigh County and the City to be existing or potential sources of inflow and infiltration (I&I) into the wastewater system and the city is under a Consent Order and Agreement with the US EPA to reduce sources of I&I into the system. Portions of the sewer collection system date to the early 20th Century. The system consists of 283 miles of pipes and 7,500 manholes, the vast majority of which are primarily of brick construction.

Initially, the Authority designated approximately 50 manholes within the system that were suspected to be in need of repair and asked Isett to conduct inspections of 10 of the manholes.  Isett devised a system to allow for the inspection of all 50 manholes within the time frame allotted for the inspection of 10.

Isett developed a device which was lowered into each manhole to photograph inlets and pipes; video and still images were saved to a disc and supplied to the client.  Isett also documented the exterior of each manhole cover.

Following that initial inspection and in subsequent years, Isett was tasked with conducting inspections of the approximately 75 to 100 manholes for possible I&I issues, compile a list of rehabilitation recommendations and prepare a cost estimate for the repair of designated manholes in each annual project. The inspections were used by the Authority, the City and Isett to determine which manholes needed to be rehabilitated utilizing a Cured-in-Place-Pipe lining system and/or if the existing frame and cover to be replaced, or some other alternate method could be used to secure the existing frame and cover such a strap system or concrete collar. In the manholes recommended for rehabilitation, conditions ranged from evidence of inflow to small cracks to gaps in the bricks. Various rehabilitation alternatives were explored, examining different processes, materials and costs.

Based upon client preferences, Isett prepared construction documents, assisted with bidding and provided construction administration and observation in the field.

In cooperation with the City of Allentown and the Lehigh County Authority, Isett was able to prioritize the extent and method of the manhole rehabilitation in the most cost effective manner to further eliminate inflow from the sanitary sewage collection system.