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World Environmental and Water Resources Congress 2017 384

side of the central section of the dam,” but Hurlbut’s answers suggest BWWS ignored the issue
of uplift relief on the steeply sloping abutments. It was the two sloping abutments of the dam that
failed catastrophically, not the main section. The enormity of this problem was not revisited in
any significant detail until the untimely failure of the Malpasset arch dam in 1959.

Figure 3. Plan of the dam dated November 1924, with the locations of the 10 test holes that
were converted to uplift relief wells, split into rows of three shallow and seven deeper holes
(LADWP).

Figure 4. Left pane is a maximum cross section through the dam showing the locations of
the 10 uplift relief wells beneath the upstream third (Rogers, 1995). Right pane shows the

likely impact of uplift relief beneath the dam’s main section, prior to caulking of the
transverse shrinkage cracks in early 1928.

World Environmental and Water Resources Congress 2017