DOUBLE PULLING HEAD

  Over a period of approximately 10 years, the City of Vancouver has been replacing laterals and services by utilizing pipe bursting technology.   This system employs continuous lengths of HDPE pipe, which is not only very durable but is resistant to root infiltration which is of particular importance to the City because of the large number of trees and shrubbery planted along our boulevards.  Using this type of pipe has helped considerably in reducing the number of flooding claims made against the City. 

  While this method brings certain gains to our operation, the difficulty arises when a single combined line is to be replaced with 2 new separate pipelines.  In this application, standard pipe bursting technology becomes essentially unusable and subsequently, we become restricted in our installation methods, reverting to traditional open cut techniques, that is until the arrival of the FALCON double pulling head. 

  Until recently, the City contended with added trenching costs when installing two pipes as separate services, as well as the added complication of trees planted in conflicting locations along the boulevard.  It therefore seemed logical to mimimize trench work required by developing a bursting head, which would lay two new pipes in place while being pulled through a single existing pipe.  In a concerted effort involving both operating and administrative staff, a design was conceived and a prototype later manufactured in the City’s Machine Shop.   After testing the new head over approximately twenty jobs, it was proven to negotiate bends and maintain grade without twisting or crossing over of the second pipe.

  This innovation has now been extended to performing repair work whereby we are now able to install a second dedicated storm connection to the property for future use when relaying a damaged combined service is required.  This “extra” work is recorded with the intention of recuperating our costs for the second pipe at the time the property is redeveloped.

  Since the Falcon’s introduction, the work is being performed more efficiently and service to the taxpayers has improved by minimizing the impact of construction in the business districts and residential neighbourhoods throughout Vancouver.

Submitted by: Gregg Lowes, Superintendent, Sewer Maintenance