Design Considerations for Water Supply Intakes on the Great Lakes

Intake facilities have more impact on the operation, maintenance, and value of a water system than any other component. The location, type of inlet structure, and conveyance conduit directly controls water quality and quantity, which controls the design of the treatment and delivery facilities. Further, intake facilities typically represent the largest unit cost ($/MGD capacity) than any other component in a water supply system. Before any consideration can be given to the intake location and design, the water quality and quantity parameters must be determined. For the Great Lakes’ intakes, water quality is usually a more significant issue than the available quantity, and the best source of water may not be the closest. Intake facilities include three primary components: the inlet structure, pipeline, and shore facilities. A case study will be presented to illustrate the challenges, such as icing, ship traffic, invasive mollusks, and marine construction. This new intake system consisted of 6,900 feet (2,103 m) of pipe, two submerged timber cribs, and two stop-log chambers. Approximately 2,000 feet (610 m) of the pipeline was installed by tunneling with the remaining installed by trenching.