Design and Construction of a Covered Concrete Reservoir

Abstract

Eugene, Oregon, with a population of about 22,000 gets its water from the McKenzie River, a stream with a minimum flow of 1500 second feet and a drainage area of about 1000 square miles above the water supply intake. It has its source high in the Cascade mountains near the base of the snow clad Three Sisters. The water is conveyed to the city through a 30-inch steel conduit seven miles long and is delivered to the filtration plant by gravity. The water is soft and of good quality and although it is Coli negative a fairly large percentage of the time, it can not be used with safety without chlorination. During storm periods, amounting to a total of 10 to 15 days each winter, the water is of such high turbidity as to require treatment by coagulation and rapid sand filtration. Throughout the remainder of the year no coagulant is used and the water passes through the filters which act only as strainers for the removal of floating and suspended matter. The resulting effluent is of excellent quality and is under the control of a bacteriologist at the University of Oregon. The reservoir which is the subject of this paper was constructed in 1926 on the site of an older and much smaller one which was built in 1887 and had been in continuous use from that time until its destruction in clearing the ground for the erection of the new one. Its location is on an elevation known as Skinner's Butte, named for Eugene Skinner, the first white settler on the ground now occupied by the City of Eugene and after whom the city also is named. This Butte was owned by the local water company from whom the city purchased the water system in 1908 and the title to this property, about 60 acres, at the end of the main street and about one-half mile from the center of the business district was acquired by the city at that time. A few years later by a vote of the people it was taken