Delivering a Critical Raw Water Transmission Line Using Design-Build; The Perspective from Gilbert of Gilbert, AZ

摘要

The Town of Gilbert, AZ, needed to meet the potable water demands of their existing and future customers. One water resource strategy was to utilize their Colorado River water allocation and build a new water treatment plant (WTP). This entailed constructing a 13-'/2 mile, 48-inch diameter pipeline to convey raw water from the Central Arizona Project (CAP) Canal to the San Tan Vista WTP. Gilbert's major challenges included:1.Complete the project within 30 months to allow the WTP to be commissioned prior to the 2009 warm weather, high water use season.2.Only one mile of the pipeline could be routed within Gilbert's boundaries; the remainder required use permits, right-of-way (ROW), or easements from over 200 public agencies and private landowners in adjacent communities.3.Meet the budget agreed to by Gilbert and the City of Chandler, an equal partner in the project.To complete the $37 million pipeline on schedule, Gilbert chose Design-Build (DB) as the project delivery method. Gilbert also selected a Project Management/Construction Management (PM/CM) consultant to lead the project. This method proved successful for Gilbert and included several innovative elements:4.Task the DB Team to take the lead in obtaining the necessary right-of-entry, ROW, and/or easements from over 200 public and private landowners.5.Negotiate multiple guaranteed maximum prices (GMP) with the DB Team to provide flexibility in executing the work to meet the schedule while providing the best value for Gilbert and Chandler.6.Empower the DB Team to use their creativity to obtain the best value. This included (1) completing a pipeline routing study that determined the preferred alignment using both monetary and non-monetary criteria, and (2) using Ductile Iron Pipe (DIP) instead of an alternate with a 27% lower material cost because DIP resulted in a lower installed cost.