PERMFILE64662

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 14A Landslide Study Geo-Hydro Consultants 1980
• Media Type: D
• Archive: No

- 13 -

eliminated and replaced by a cut slope 2 1; at the same time,
the potential for saturation should be eliminated to achieve
long-term stability. i
I
~; The following conclusions can be made and recommendations
formulated for the proposed construction:
~. 1. It is evident that any unsupported excavation at .the ~
steep slopes such as the one above the entry 5 would result
~ in a slope failure if the soils are saturated. In dry con-
. ditions, the excavation may be temporarily stable; saturation ~
at some later date would cause a failure. In order to avoid
the risk of failure, any excavations in steep slopes should be i
carefully dewatered prior to the excavation. i
2. Excavations at flatter slopes such as the slopes above
the entries 1, 2, 3, and 4 might be temporarily stable even if
~~ saturated. For Iong-term stability, the potential for saturation
should be avoided.
3. It is impractical to design any retaining structure to
resist a potential slide; retaining structures could be designed
using conventional design methods only if effective drainage is
' implemented in the slope portion behind the structure. LIe
recommend that an effective underground drainage system be
utilized to prevent the saturation of the surficial layer; thick-
~ Hess of the same should equal at least the height of the struc-
~'.
~~ tore (including the below ground portioa). The thickness should
be at least 10 feet. For a slope configuration and height
i of the retaining wall such as indicated on Plate 8, the drainage
should be effective at some 100 - 120 feet behind the structure;
~' it could be proportionally shorter for a lower structure.
I
4. The analysis of
the
entry 3 shows
that
the retaining
• wall could be eliminated and replaced by a cut. Factors of
ow+,rso mwunm..c