Long Quarters Force Main Outfall

longquartersVerified Structural Lining; An Engineered Solution for Force Main Outfall Manholes.

Long Quarters Force Main Outall; Baltimore County Bureau of Public Works, Towson, MD.
A two mile 36”/27” force main that carries sanitary flow from a major pump station servicing one of the county’s largest population hub of retail and commercial areas.  The pump station hammer pressure produces extreme air and water pressures at the head of the flow.  This head pressure had led to the complete structural failure of several brick structure outfall manholes in terms of dislodging bricks from the manhole barrel and chimney sections.  The failure in these manhole structures cause the surrounding earth to enter these structures causing major sinkholes to develop in the area.  This type of manhole failure is determined to be a mode of structural degradation known as “fully deteriorated host structure” in engineering terms.
The solution to rectify these manhole structural failures as determined by the bureau’s civil engineering staff required trenchless rehabilitation capabilities that address two priority capabilities.  The first capability specified for a lining system approval is the ability of the system to provide a verified structural design for lining thickness based on third party verified physical structural strengths.  The capability to provide a structural thickness that will be designed utilizing the engineering calculations found in the ASTM f1216 designate for structural design of polymer reinforcement of buried circular composites.  The second requirement of the cured-in-place polymer lining system to be used will have the capability for immediate reinstatement of the sanitary flow to the polymer system as it is applied.  Bypass of this force main flow is not feasible and the wet well capacity at the pump station will only allow for a two hour shutdown.