The NL1 Pump Station Value-based Design Review involved investigation of various options for replacing the NL1 pump station. The NL1 pump station was initially installed as a temporary service facility to regulate flows while downstream tunnels were being constructed as a part of the North Edmonton Sanitary Trunk (NEST) and had reached the end of its service life. NEST was proposed in 1994 as a solution to the capacity issues facing the northern part of the City of Edmonton. The NL1 tunnel, part of NEST, employed a pump station that was in very poor condition.

The station was wedged into the boulevard, which affected pedestrian/bicycle traffic and ease of access for Drainage Operations as well as creating constructability challenges. Dealing with various options for locating the new pump station, each with their own set of disadvantages, was problematic and required a systematic approach.

SMA was retained to conduct a value-based design review for options for replacement of the NL1 pump station, using the Analytical Hierarchy Process to evaluate the options, and coming up with a functional value, which was then divided by cost, yielding a clear quantitative result. The value engineering analysis included hydraulic modelling of flows, life cycle cost estimates, risk assessments, and operability and safety analysis.

The work plan used by SMA involved a multi-phase process of data collection and background information review and modelling, and system performance evaluation, incorporating hydro-technical assessment, erosion assessment, geotechnical investigation, and cost estimation into the traditional value engineering approach.

The original location’s history of odor and construction noise complaints translated into the need to include stakeholder/public acceptance high on the list of criteria for choosing the final option. The option ultimately chosen was one which allowed for ease of access for both construction and operations and maintenance, had greatest stakeholder support, and which delivered the highest value.