Title  : McMurdo's Wastewater-dispersion
Type   : Antarctic EAM
NSF Org: OD / OPP
Date   : March 01, 1991
File   : opp93025


                                       DIVISION OF POLAR PROGRAMS
                         OFFICE OF SAFETY, ENVIRONMENT AND HEALTH
                                                     202/357-7766
MEMORANDUM

   Date:  March 1, 1991

   From:  Environmental Officer, DPP

Subject:  Environmental Action Memorandum (Information on
   Dispersion of McMurdo Station's Wastewater

     To:  Files (S.7 - Environment)


Mr. Steven F. Railsback of the Environmental Sciences Division at
Oak Ridge National Laboratory has submitted the paper,  "Dis-
persion Characteristics of a Submerged Wastewater Outfall at
McMurdo Station", to the Journal of Cold Regions Engineering.
Also, he has submitted an abstract on his McMurdo wastewater
modelling effort for the special session on "Measuring the Fate,
Behavior and Effects of Contaminants in Polar Environments" being
planned for the First International Ocean Pollution Symposium to
be held April 28 to May 2, 1991, in Puerto Rico.

The paper and abstract illustrate one type of assessment that the
U.S. Antarctic Program's Facilities Engineers and Environmental
Engineers will find useful in implementing environment goals
related to the management of wastewater at antarctic coastal
installations.  Below you will find a copy of the abstract for
use in future work.  When the paper is published, I will provide
you with a copy.


         Dispersion and Fate of Wastewater Released from
 Submerged and Surface Discharges at McMurdo Station, Antarctica

                      Steven F. Railsback


     Domestic wastewater at McMurdo Station has historically been
discharged directly to the ice-covered ocean surface, the common
practice at Antarctic stations.  As part of a program to reduce
environmental effects of McMurdo's wastewater, a submerged
outfall was recently installed.  Prior to construction of the
outfall, a dispersion model was used to predict its impacts.
                               -2-


     Input data on flow rate, salinity, and temperature of both
the discharge and the receiving waters were obtained from past
studies and additional measurements.  McMurdo Station's effluent,
a combination of domestic sewage and desalinator brine, is pre-
dicted to be buoyant under all foreseeable conditions.  The
dispersion model predicted that the effluent plume would rise to
the surface while being diluted with ambient water to 1/100 to
1/500 of its original concentration.  The model predicts greater
mixing when the effluent flow rate is low and the ambient current
is fast.  Additional mixing can be obtained with minor design
changes in the outfall.

     Models of dispersion from discharges to the surface of
ice-covered waters are not available for comparison.  Field data
and a conceptual model indicate, however, that the historic
surface discharge probably mixes relatively little with ambient
water before the effluent spreads along the shoreline and
underneath the ice.  The submerged discharge is predicted to
significantly reduce effluent concentrations at the ice-water
surface.



                                Sidney Draggan


cc:  Safety, Environment and Health Officer, DPP
     Facilities Engineering Projects Manager, DPP
     Environmental Engineer, DPP