HomeMy WebLinkAboutCT 2017-0004; SIX ON MADISON; STABILITY FOR TEMPORARY EXCAVATION; 2019-09-10ALLIED EARTH TECHNOLOGY
7915 SILVERTON AVENUE, SUITE 317
SAN DIEGO, CALIFORNIA 92126
TEL: (858) 586-1665 (619) 447-4747
E-MAIL: ROBERTAET@AOL.COM
ROBERT CHAN, P.E.
September 10, 2019
Oak & Madison LLC
7851 Mission Center Court
San Diego, CA. 92108
Attn: Mr. Mehran Saberi
Subject: Project No. 18-1106135
Stability of Temporary Excavation
Proposed Six-Unit Condominium Building Site
3095 Madison Street
Carlsbad, California
Dear Mr. Saberi:
Reference is made to our geotechnical investigation report, same Project Number as above, dated
November 20, 2018.
It is our understanding that, as part of the site development, excavations for the proposed car lift
will be required. Along the alley side, the outer face of the subterranean car lift will be 6.00 feet
from property line. Vertical excavations on the order of 7 feet will be required to construct the
basement retaining walls of the car lift.
In the above geotechnical investigation report, late to middle Pleistocene Old Paralic Deposits Unit
6-7 were encountered on site in the form of medium dense to dense brown fine sands. The Old
Paralic Deposits were overlain by a 6 - 12 inch layer of loose topsoil.
Based on the on-site subsurface soil conditions, it is recommended that excavation for the
subterranean car lift be accomplished at a vertical inclination for a height of 5 feet. Above a
height of 5 feet, the slope inclination should be flattened to a slope ratio of 1 : 1 (horizontal
vertical).
Project No. 18-1106E5 Oak & Madison LLC 09/10/19 Page 2
3095 Madison Street
The temporary excavation configuration is shown on Section D on Sheet 2 of the grading plan.
After the subterranean car lift basement wall has been constructed and properly backfilled, the
building wall and concrete slab can then be constructed.
The temporary excavation will be adjacent to the existing alley. The light, sparse vehicular traffic
along the alley will not affect the stability of the temporary excavation.
Since the temporary excavation configuration can be safely accomplished within subject
property, without encroachment into the City right-of-way, no temporary shoring was
recommended by our firm, or required.
Respectfully ubrni
,,,
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ALLIED EA LOGY
itROBERT AN, P E