specs

Geotechnical Investigation South River Place, Gasser Drive, Napa 29 December 2010
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Settlement
Our investigation of the site included an evaluation of consolidation settlement of the subsurface
soil materials. The current and previous test borings and pits indicate that settlement of the near
surface fill materials will occur if not mitigated prior to development. The anticipated settlement
from the proposed fill material and weight of the structures is considered excessive. Therefore,
the near-surface fill materials should be mitigated/densified prior to development to minimize
total and differential settlements. The fill materials can be mitigated by removal and
recompaction or by in-situ densification.
In addition to the potential for settlement of the near surface existing fills, we evaluated the
potential for settlement due to consolidation of the native subsurface clay soils. We performed
two consolidation tests which revealed that the clayey materials in the vicinity of Borings 2 and 3
are currently under-consolidated and subject to settlement. Our settlement analysis of the underconsolidated
materials indicates that 0.5 to 1.2 inches of long-term total settlement may occur
after the buildings are constructed. Differential settlement can be assumed to be one-half of the
total settlement, or up to 0.6 inches.
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KC ENGINEERING COMPANY Project No. VV3200 Page 13 of 123