Corridor Analysis of a Raw Water Transmission Pipeline

The City of Enid (City) is located in Northwest Oklahoma and services a population of over 50,000 residents. The City of Enid water supply infrastructure relies completely on an existing groundwater supply. Like many municipalities, aging public works infrastructure and increasing customer demands require continuous infrastructure maintenance, improvement, and expansion. The City of Enid proactively initiated a surface water supply program to supplement the existing ground water supply in order to meet increasing demands and diversity its water portfolio. In 2015, the City of Enid authorized Garver, LLC and Freese and Nichols, Inc. to perform a raw water transmission study and hydraulic analysis to deliver raw water from Kaw Lake to Enid’s proposed water treatment plant, approximately sixty-eight (68) miles away. This paper will focus on the major analysis methods and lessons learned during the corridor study of the raw water transmission pipeline. The study includes data gathering from several public and private agencies. Preliminary corridor alternatives were produced on the basis of minimizing known potential environmental and archeological impacts, potential impact to landowners, constructability concerns, topographic characteristics that negatively impact hydraulic profile, and maximizing permanent easement access. The preliminary corridors were broken up by length into geographical classifications that represent specific construction challenges. A corridor evaluation matrix was developed utilizing geographical, environmental, maintenance, and installation characteristics to classify sections of the corridor as a means of comparing the alternatives. Hydraulic models of the recommended corridor were developed based on Kaw Lake water level data, contour data obtained, and previously developed flow requirements. These models were used to determine pumping alternatives, and potential pipeline sizing. A pipeline optimization analysis was performed to compare the capital cost of various pipeline sizes to the annual pumping (power) costs over a twenty-five (25) year span. Cost estimating was included in the study based on corridor characteristics linked with data obtained on recent market trends.