1 Answer

The City of Stillwater owns and operates two (2) 36-inch diameter steel pipelines – a raw
water transmission main line that transfers raw water approximately 36 miles from Kaw Lake to the City
water treatment plant and a finished water pipeline that transfers treated water from the water treatment
plant approximately 7 miles to the area near the Oklahoma State University water treatment plant.
The 36-inch diameter pipeline was designed by Williams Brothers Engineering Company in 1979 and
constructed by the Willbros Energy Service, Inc. in 1981. The pipeline is made up of 0.312 inch thick
steel pipe, imported from Italy in 1981. The portions of the line that pass under the Arkansas River at
two locations and under the OG&E (Sooner) reservoir are 0.500 inch thick steel pipe. The pipe under
the Arkansas River has a 4-inch thick concrete exterior coating and the pipe under the OG&E reservoir
has a 2-inch thick concrete exterior coating. The pipe is internally and externally protected with coal tar
enamel throughout and the external surface is also tape wrapped. In addition to the coatings, the pipe
is externally corrosion protected with an impressed current cathodic protection system. The pipeline has
been in operation for approximately 30 years. There are no in-line valves or surge protection devices on
either pipe lines.
The raw water flows by gravity through a 48-inch conduit from the base of the Kaw dam to the City
owned and operated Kaw pump station. Three 200 hp pumps were installed originally and two 1000 hp
pumps have been added to boost the pumping capacity. Normal operation is to have one, two or three
of the smaller pumps in operation. To date, the City’s water demand has not created the need to
operate the two big pumps simultaneously. Furthermore, the larger pumps are never operated in
tandem with the smaller pumps. The table below illustrates the flow rates and pressure in the 36-inch
diameter raw water steel pipe based on the typical pump operations. The pressure at the pump station
is monitored by a SCADA system which records transient pressures during changing pump operations.
The scale of measurement is from 0 to 200 pounds per square inch-gage (psig). With the present
instrumentation set-up, any start-up pressure occurrence in excess of 200 psig is not being recorded.