Winter Operations : March 1970 / Norbert W. O'Hara ... [et al.].

DIVE REPORT

Date: D1 March 1970
Location: Donald C. Cook Nuclear Plant site, Lake Michigan
Depth: 12 feet Visibility: 4-5 feet Bottom Time: 15 minutes
Wind Direction: NW Wind Speed: 10-15 knots
Sea Height: 2 to 3 feet Direction from: NW
Team: Robert F. Anderson and John Krezoski
Objective: Locate and recover glass plates from two periphyton collectors set
last August in 15 and 30 feet of water on the range established bv the
two red and white barber poles north of the Cook plant site.
Report: Ice conditions at the dive site on 10 March 1970: Open water to
horizon, areas of pack ice also visible on the horizon. Open pack ice
drifting close to shore.
Work was conducted from a 16-foot aluminum boat. Soundings were taken
to determine where to begin a search pattern for the periphyton collector
located in 15 feet of water. Soundings in the area of the 15-foot depth
contour revealed a depression with a depth of 19 feet. Since a lead line
was used for sounding, it was impossible to determine whether this
depression was the base of a shoal or the result of ice scour.
The dive plan was to start a search pattern at a depth of 12 feet and
work out from this point. After positioning the boat on the range poles
we made our descent on the anchor line and conducted a 100-foot circular
search pattern using a sweep line. During our descent a strong current
from the northwest was observed. Bottom type was a medium sand. Irregular
ripple marks were observed on the bottom running parallel to the shoreline.
Small amounts of organic detrital material had collected between the ripple

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