3.3 OFFSITE MONITORING GROUP

Four two-man teams and one five-man team supervised by the chief
offsite monitor constituted the Offsite Monitoring Group. Before the
detonation, the four two-man teams established monitoring posts in
towns outside the test area. These towns were Nogal, Roswell, Fort
Sumner, and Socorro, all in New Mexico. The five-man team remained at
Guard Post 2 to assist in evacuation of nearby residences if the
TRINITY cloud drifted in that direction. These residences, the Fite
house and the homes in the town of Tokay, were 24 and 32 kilometers
northwest of ground zero, respectively. Since the cloud drifted to
the northeast, evacuation was not required. All offsite monitoring
teams were in radio or telephone contact with personnel at the Base
Camp (11).

Offsite monitoring teams in areas northeast of ground zero encountered
gamma readings ranging from 1.5 to 15 R/h two to four hours after the
detonation. Three hours after the detonation, surveys taken in
Bingham, New Mexico (located 30 kilometers northeast of ground zero)
found gamma intensities of about 1.5 R/h. Radiation readings at the
town of White, nine kilometers southeast of Bingham, were 6.5 R/h
three hours after the detonation and 2.5 R/h two hours later. Another
team monitoring in a canyon 11 kilometers east of Bingham found a
gamma intensity of about 15 R/h. Five hours later, the intensity had
decreased to 3.8 R/h. It was estimated that peak intensities of gamma
radiation from fallout on shot-day were about 7 R/h at an occupied
ranch house in this canyon area (1; 11; 19).

Monitoring teams resurveyed these towns about one month after the
TRINITY detonation. At Bingham, gamma readings of 0.003 R/h and