Upgrading of a Railroad Yard Wastewater
Treatment Facility — A Case History
ALBERT C. GRAY, JR., Manager
JAMES G. HANEY, Engineer
Gannett, Fleming, Corddry, & Carpenter, Inc.
Harrisburg, Pennsylvania 17105
INTRODUCTION
It is a widely recognized fact that the railroad industry in the United States is facing a
multitude of problems at this time. Not the least of these is the charge of cleaning up its
wastewaters to conform to the increasingly stringent standards mandated by an
environmentally conscious public. The results of environmental pollution from railroad
operations are no more catastrophic than are those of many industrial effluents, but they
are more visible than most. One of the principal contaminants of wastewaters arising from
railroad maintenance operations is oil, and oil at very low concentrations can readily be
observed when discharged to natural waters. A visible oil slick will result from oily surface
loadings as low as 25 gallons per square mile (1). This quantity of oil can easily be produced
by a few thousand gallons of wastewater from a railroad yard even if that wastewater is
relatively clean (i.e. 50 to 100 mg/1 oil). Compounding the problems are the other less visible
contaminants of concern to the regulatory agencies and commonly characterizing
wastewaters from the railroad industry such as BOD5, ammonia nitrogen, suspended solids,
phosphorus, ABS (detergents), and various trace metals.
Railroads additionally face some logistical problems associated with waste treatment
which are somewhat atypical of industrial waste sources in general. Since a railroad
company may own and operate over several hundred miles of track, its maintenance
facilities may be distributed over a large area. Therefore, elaborate waste collection and
transfer systems may be required, or, more likely, a number of waste treatment facilities will
be employed. Even a single maintenance or freight transfer location may extend for several
miles and produce several wastewaters of differing characteristics depending upon the
operations performed. Also to be considered is the non-point source drainage which may
flow into a watercourse adjacent to a railroad right of way. To date this pollutional source
has been given little attention but it may well become an important facet of the railroad
waste problem.
Since free oil has been the major pollutant of concern to the railroad industry most of
the existing treatment facilities were designed principally for oil separation. Commonly
employed are tanks with surface skimming devices such as the oil separators recommended
by the American Petroleum Institute (2). Where a significant fraction of the oil has become
emulsified some method, usually chemical flocculation, must be implemented to break the
emulsion prior to surface skimming. As the regulatory agencies become more exacting with
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