HomeMy WebLinkAboutCDP 2017-0021; OCEAN STREET RESIDENCE; ADDENDUM TO LIMITED GEOTECHNICAL INVESTIGATION; 2018-07-08Alan Shafran
EAST COUNTY SOIL CONSULTATION
AND ENGINEERJNG, INC.
10925 HARTLEY ROAD, SUITE "I"
SANTEE, CALIFORNIA 92071
(619) 258-7901
Fax (619) 258-7902
1673 Amante Court
Carlsbad, California 92011
Subject: Addendum to Limited Geotechnical [nvestigation
Proposed Single-Fa111ily Residence
2680 Ocean Street ,
City of Carlsbad, California 92008
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AUG O 2 2018
LAND DEVELOPMENT
CNGINEERING
July8,2018
Project No. 17-110605
pr~~e-i tD: CDP2011 -002(
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Reference: "Limited Geotechnical Investigation. Proposed Single-Family Residence, 2680 Ocean
Street, City of Carlsbad, California," Project No. 17-1106D5, Prepared by East County Soil
Consultation and Engineering, Inc., Dated March 2. 2017.
Dear Mr. Shafran:
In accordance with your request, we have prepared this addendum to address the retaining walls
for the proposed single-family residence at the subject site.
The grading plans prepared by Pacific Overland Engineering & Surveying of Vista, California
indicate the existing retaining wall at the rear of the property will be replaced with a new one. The
new wall will have a maximum height of 5 .33 feet and a setback of 10 inches from the rear property
line. Questions have been raised regarding the type of backfill and the proposed 6-foot high vertical
cut behind the wall to facilitate construction.
Based on the dense consistency of the underlying terrace deposits, it is our opinion that a temporary
vertical cut up to 6 feet will be stable. Due to the setback limitation, the retaining wall backfill may
consist ofa I-inch maximum open-graded aggregate (drain rock) wrapped in a Miraft 140N filter
fabric or equivalent.
Cantilevered retaining walls should be designed for an "active" lateral earth pressure or 35 pstlft
(35 pcf EFP) for approved granular and level backfill conditions. Where the walls support 21 I: 1 V
sloping backfill, the equivalent active fluid pressure should be increased to 45 pcf. Walls subject
to uniform surcharge loads should be designed for an additional uniform lateral pressure equal to
one-third (1/3) the anticipated surcharge pressure.
Another additional lateral earth pressure due to earthquake motions of 26 pcf EFP may be applied
using an inverted triangular distribution if required.
Soil design criteria, such as bearing capacity, passive earth pressure and sliding resistance as
recommended under the Foundation and Slab recommendations section of the referenced
geotechnical report may be incorporated in the retaining wall design.
Footings should be reinforced as recommended by the structural engineer and appropriate back
drainage provided to avoid excessive hydrostatic wall pressures. As a minimum, we recommend a
fabric-wrapped crushed rock and perforated pipe system.
If we can be of any further assistance, please do not hesitate to contact our office.
Mamadou Saliou Diallo, P.E.
RCE 54071, GE 2704
MSD\md