HomeMy WebLinkAboutSDP 09-05; Palomar Commons; Site Development Plan (SDP) (7)0^^^Z7 GeoteMcdSEnvlramnenlal Solutions
November 21, 2011
Revised November 28,2011
Mr. Mark Radeiow
Vice President/Senior Project Manager
Sudbeny Properties, Inc.
5465 Morehouse Drive, Suite 260
San Diego, CA92121
Subject: Geotechnical Parameters for Design of Proposed MSE Walls
Proposed Retail Development-Palomar Airport Commons
Palomar Airport Road and El Camino Real
Carlsbad, San Diego County, California
EEI Project No. SUD-70986.7
Reference: EEI, 2010, Geotechnical Evaluation, Proposed Retail Development, Palomar Airport
Commons, SWC of Palomar Airport Road and El Camino Real, Carlsbad, California, EEI
Project No. SUD-70986.4, dated January 13,2010.
EEI, 2011, Geotechnical Geotechnical Update and Review of Grading Plans, Proposed
Retail Development- Palomar Airport Commons, Palomai- Aiiport Road and El Camino
Real, Carisbad, San Diego County, Califomia, EEI Project No. SUD-70986.4, dated
August 1,2011.
Dear Mr. Radeiow:
Pursuant to your request and authorization, we are providing herewith the recommended geotechnical
parameters for use in the design ofthe proposed mechanically stabilized earth (MSE) walls at the project
site. This letter should be considered as an addendum to our referenced geotechnical evaluation report
and the referenced geotechnical update report.
We understand that three MSE walls (currently designated as Walls D, E, and F) are planned at the
project site. The geotechnical design paiameters are provided below for the three MSE walls (i.e..
Keystone, Loffel, Earthstone, Geogrid, etc.).
2195 Paraday Avenue, Suite K, Carisbad Califomia 92008-7207 Ph: 760-431-3747 Fax: 760-431-3748 wnv.eeitiger.com
Geotechnical Parameters for Design of Proposed MSE Walls November 21,2011, (Rev. November 28,2011)
Palomar Airport Commons, Carlsbad, CA EEI Project No. SUD-70986.7
Recommended Strength Parameters
Based on the geoteclmical data and recommendations presented in our referenced reports and our past
experience with similar soils in the general vicinity of the project site, we recommend that the following
soils parameters be used for design of the proposed reinforced earth walls:
MSE Walls D and F
Soil Parameters
Internal
Friction
Angle
(Degrees)
Cohesion
(psf)
Moist Unit
Weight (pcf) Soil Type
Reinforced Soil 32 0 120 Compacted select SP-SM
materials with PI<10.
Retained Soil 23 200 120 Compacted onsite SC-CL
materials.
Foundation Soil 23 200 120 Compacted onsite SC-CL
materials.
MSE Wall E
Soil Parameters
Internal
Friction
Angle
(Degrees)
Cohesion
(psf)
Moist Unit
Weight (pcf) Soil Type
Reinforced Soil
(Sta. 1+80 to 4+37) 34 0
0
120 Compacted select SP-SM
materials with PI<10.
Reinforced Soil
(Sta. 1+80 to 4+37) 32
0
0 120 Compacted select SP-SM
materials with PI<6.
Retained Soil 32 0 120 Compacted select SP-SM
materials with PI<10.
Foundation Soil 32 0 120 Compacted select SP-SM
materials with PKIO.
The backfill materials should be placed in lifts no greater than 8-inches in thickness and
compacted at 90 percent relative compaction at optimum moisture content or higher as
determined by ASTM test procedure D 1557-00.
Allowable Bearing Capacity
An allowable bearing capacity of 2,500 pounds per square foot, including both dead and live loads, may
be used for Walls D and F if footings are founded at a minimum of 12-inches below finish grade into
properiy compacted fill or dense weathered sedimentary fonnational materials. An allowable bearing
capacity of 4,000 pounds per square foot, including both dead and live loads, may be used for Wall E if
footings are founded at a minimum of 12-inches below fmish grade into properiy compacted select fill as
indicated in the above table. The allowable bearing may be increased by one-third when considering
short-term live loads (e.g. seismic and wind loads).
Geotechnical Parameters for Design of Proposed MSE Walls November 21,2011, (Rev. November 28,2011)
Palomar Airport Commons, Carlsbad, CA EEI Project No. SUD-70986.7
Seismic Design Parameters
Maximum considered ground motion maps provided in the California Building Code (CBC, 2010) were
utilized with coordinates of 33.1278° north latitude and 117.2695° west longitude, to determine the site
seismic parameters. EEI utilized seismic design criteria provided in the CBC (2010).
In accordance with the guidelines of the CBC (2010), the spectral parameters for the site (based on a Site
Class B soil) are estimated to be Sj = 1.140g and Si = 0.43 lg. Based on our review of the geotechnical
data obtained during our referenced subsurface exploration (particularly with respect to the observed
depth of the Tertiary-age Santiago Formation), it is our opinion that the site can be classified as Class C
per the CBC (Table 1613.5.2). Consequently, Site Coefficients Fa= 1.0 and Fy = 1.369 appear to be
appropriate for the site. Based on this infonnation, the adjusted maximum considered earthquake spectral
response parameters SMS= 1.140g and SMI = 0.59 Ig are recommended for seismic design of the project.
Assuming an occupancy category of II (Table 1604A.5), an SDS value of 0.760g and an SDI value of
0.394g, proposed cominercial buildings at the site can be assigned a seismic design category of D [Table
1613.5.6 (1) and (2)]. Final selection of the appropriate seismic design coefficients should be made by
the structural consultant based on the local laws and ordinances, expected building response, and desired
level of conservatism.
In keeping with the 2010 CBC (2009 IBC seismic design) criteria, when dividing the above SDS value by
2.5, a peak ground acceleration of 0.30g is obtained. A peak ground acceleration of 0.30g may be used
for seismic design puiposes.
Utilizing the Mononobe-Okabe method of analysis and incorporating the estimated peak ground
acceleration listed above, we estimate the seismic resultant of lateral pressure for a wall with level
backfill to be I4rf lbs, where H is the retained height in (feet).
The seismic resultant is expected to be exerted in addition to the lateral earth pressures presented above.
The seismic resultant may be assumed to be applied at a height of 0.6H above the wall base. The
magnitude and location of the seismic resultant are based on the assumption that the walls are constnicted
in accordance with the recommendations contained herein and in our referenced reports.
Back Drainage
Retaining walls should be provided with an adequate back drainage system in accordance with the
recommendations contained in our referenced report and as required by the wall manufacturer/designer.
Proper back drainage can reduce the potential for the accumulation of hydrostatic pressures behind the
walls. Location of proposed onsite storm water facilities (i.e., BMP's) in the vicinity of the walls and the
potential for increased hydrostatic pressures should be considered in design of the walls.
Temporary Backcuts
Temporaiy excavations or backcuts within the onsite materials should be stable at 1H:1V inclination for
short durations during construction but should not exceed 15 feet in height.
Geotechnical Parameters for Design of Proposed MSE Walls
Palomar Airport Commons, Carlsbad, CA
November 21,2011, (Rev. November 28,2011)
EEI Project No. SUD-70986.7
Construction Obsei'vations and Testing
All foundation excavations and wall backfilling should be observed and tested by a representative of this
office to check for compliance with the recommendations of this report and the referenced reports, and to
check that the soil conditions are consistent with those stated herein.
Other Considerations
All other recomraendations, terms and conditions presented in our referenced reports remain applicable to
the project and are included by reference herein.
Limitations
This letter has been conducted in accordance with generally accepted geotechnical engineering principles
and practices. Findings provided heiein have been derived in accordance with the current standards of
practice, and no warranty is expressed or implied. Standards of practice are subject to change with time.
This letter has been prepared for the sole use of Sudbeiry (Client) within a reasonable time from its
authorization. This letter should not be relied upon by other parties without the express written consent of
EEI and the Client. This letter contains information which may be used in the preparation of contract
specifications; however, the report is not designed as a specification document, and may not contain
sufficient information for use without additional assessment. EEI assumes no responsibility or liability
for work or testing performed by others (including that performed during constiuction).
EEl appreciates the opportunity of be of continued sei-vice. Please do not hesitate to contact either one of
the undersigned if you have any questions or if you require additional information.
Respectfully submitted,
EEl
William R. Morrison, G.E. 2468
Senior Engineer
rr»*- 'St"
/ '
//Senior Geologist
Distribution: (2) Addressee
(2) Fuscoe Engineering, Attention: Greg Lang, one via electronic copy
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