The 35,252 -acre Oak Ridge Reservation (ORR), in the western portion of the
Appalachian Valley and Ridge province in Tennessee, has been a nuclear production and
development facility for 50 years. Contaminants in the many waste sites on the ORR
include heavy radioactive isotopes as well as many organic and inorganic compounds.
The locations, geometry, and contents of many of these waste sites are reasonably well
known, while others are poorly known, and some may be unknown. To better
characterize the known sites and locate and characterize additional environmentally
hazardous sites, a two-phase aerial survey of the ORR was begun in April, 1992. Phase
I, which began in April, 1992, consisted of aerial radiation, multispectral scanner, and
photographic surveys. Phase II, which began in November, 1992 and is described in this
presentation, consisted of a helicopter electromagnetic (HEM), magnetic, and radiation
survey. Targets of the survey were both man-made (drums, trench boundaries, burn pits,
well heads) and geologic (fractures, faults, karst features, geologic contacts).
The Phase II survey has three components: testing, reconnaissance, and high-resolution
data acquisition. To date, the testing and reconnaissance data acquisition have been
completed, and part of the data have been processed. They indicate that: 1) magnetic
and HEM data are complementary, and do not always highlight the same anomaly; 2)
under favorable circumstances, helicopter magnetometer systems are capable of detecting
groups of 4 or more 55-gallon drums at detector altitudes of 15 m or less, 3) HEM data
provide data which compare favorably with surface data collected over burial trenches, 4)
well casings seem to be related to magnetic monopole anomalies, as would be expected,
5) Changes in EM and magnetic anomaly character are related to lithologic changes and
might be used to track contacts between known outcrops.
