Combined Waste Treatment at
Grand Island, Nebraska
W, R. GIBBS, Parmer
HENRY BENJES, JR., Sanitary Engineer
Black & Veatch Consulting Engineers
Kansas City, Missouri
INTRODUCTION
During the spring and summer of 1962, investigations and studies were made
of the condition and adequacy of the existing sewerage facilities at Grand Island,
Nebraska, and a long-range plan of improvements to meet the future sewerage
service requirements in the 15 square mile study area was developed. It was
found that the greatest needs faced by the City was for extension of sewers into
new development areas, for relief of certain overloaded sewers in the older areas
of the City, and for upgrading of various sewage pumping stations and the existing
sewage treatment plant.
There are two characteristics of the area which had caused problems in the
development of the existing sewage collection system. The terrain is quite flat
with no well defined watercourses inside the developed area, and the City is underlain with alluvial sands and gravels containing a high water table connected
hydraulically with the underflow of the Platte River. Due to the unavailability of
good pipe joints in past years, an effort to keep all sewers at shallow depths above
the water table and the flatness of the terrain resulted in the construction of many
subsystems, each with its own lift station. The design of many of the lift stations
had created operating problems. The existing activated sludge sewage treatment
plant, with a capacity of six MGD, was old but it was concluded that it could be
made to serve for about 10 years with only minor improvements.
The sewage treated was essentially domestic although it was anticipated that
wastes from a small milk processing plant would receive treatment five to 10 years
in the future. The treated effluent was discharged to a ditch leading to the Wood
River approximately two miles distant. Condenser cooling water from the nearby
municipal steam-electric generating station also discharged to the same ditch and
normally provided a 10 to one dilution ratio. From the ditch, the combined effluent and cooling water flowed through the channel of the Wood River, an intermittent stream, about three miles to the Platte River. Seasonal wastes from a
sugar beet processing industry were pretreated at the source and did not receive
treatment in the municipal sewage treatment facilities. These beet wastes did
contribute to the water pollution problem in the area as they were discharged
separrtely to the Wood River.
The general developmental plan proposed included initially the construction
of new gravity sewers both to serve new construction areas and as relief sewers
where necessary, the abandonment of certain lift stations, improvements to various lift stations and the sewage treatment facilities, and the construction of one
new lift station. The second stage of construction would follow in about 10 years
with extension of the gravity outfalls to a new sewage treatment plant to be constructed at a more remote downstream site on the Wood River about one and one-
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