The Effect of pH Neutralization of
A Power Plant Effluent on
The Clinch River
JOHN S. CROSSMAN, Biologist
Teledyne Brown Engineering
Huntsville, Alabama 35807
JOHN CAIRNS, JR., Professor
Biology Department and Center for Environmental Studies
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
INTRODUCTION
The Appalachian Power Company operates a 700 megawatt steam power generating
plant at Carbo, Virginia. During the past five years this plant has been responsible for two
major industrial spills that have resulted in fish kills and other biological damage to the
Clinch River. The first spill occurred in June 1967 when the dike surrounding a fly ash
settling pond collapsed. This spill involved the release of an estimated 130 million gallons of
fly ash waste which had a pH between 12.0 and 13.0 (1). Three years after the alkaline spill,
June 1970, another accidental spill occurred when the pH controlling unit at one of the
plant's cooling towers failed. This failure resulted in the release of an undetermined amount
of sulfuric acid which killed fish and other biological organisms for a distance of
approximately 13.0 miles (2).
Preventative measures taken to avoid the occurrence of another fly ash pond spill were
to remove the ash slurry return pipe from the dike, the rip-rap along the outer face of the
dike wall was removed and a five foot wide filter zone of crushed rock was placed along the
entire length of the dike to prevent erosion, and a three foot layer of rip-rap was replaced on
the outside slope of the dike, up to approximately 14 feet, for flood protection (1). Action
was also taken to prevent pH problems such as the one that occurred in June 1970. This
preventative measure involved the installation of a new waste water treatment system
designed to control the pH of all waters discharged from the power plant to the river.
Besides controlling the pH the unit was designed to settle out grit and suspended solids,
thereby eliminating another possible environmental problem.
After the new waterwater treatment system became operational a one year instream
biological monitoring program was undertaken to determine what effects its discharges
were having upon the receiving stream's macroinvertebrate communities.
Macroinvertebrates were studied because they are: 1) relatively sessile organisms that
cannot quickly avoid environmental stresses as fish are often able to do; 2) they have rather
long and complex life histories and their presence or absence reflects the history of the
environment; 3) sampling techniques for bottom fauna are more reliable than techniques
for fish; 4) in a lotic environment with a detrivore food chain this group becomes the single
most important trophic level since all the other trophic levels depend upon them for food;
and 5) this group of organisms had been extensively studied since 1969 by the senior author.
MATERIALS AND METHODS
When the instream biological monitoring system was set up, four stations were
sampled on a monthly basis except when high stream discharges prevented it in January,
February, and May. The four stations were divided into one upstream reference station.
Station 4, and three downstream stations, stations 7, 8, and 10. These stations were located
2.0 km above the power plant and 1.1,4.7, and 18.8 km downstream of the power station,
respectively.
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