HomeMy WebLinkAbout3883; JEFFERSON STREET SIDEWALKS; PAVEMENT RECOMMENDATIONS; 2002-07-17¶b: S4Z LAA-4
July 17, 2002
Project No. 104669002
Ms. Mariel Cairns
PBS&J
175 Calle Magdaiena
Encinitas, California 92024
Subject: Pavement Recommendations
Jefferson Street North
Carlsbad, California
Dear Ms. Cairns:
In accordance with your request and authorization, we have performed sampling and laboratory testing of
subgrade soils at the Jefferson Street North project in Carlsbad, California. Subgrade soils were collected
from two locations and tested for R-value. The laboratory test results are attached. Based on the results
of our subsurface evaluation, laboratory tests, and our experience with soils similar to those encountered
at and near the site, we have assumed an R-value of 68 for the preliminary basis for design of flexible
pavements at the project site. Actual pavement recommendations should be based on R-value tests per-
formed on bulk samples of the soils that are exposed at the finished subgrade elevations across, the site
prior to paving. . .
We understand that this portion of Jefferson Street is considered a local street. Based on a Traffic Index
(TI). of 5.0. we recommend a pavement section consisting of 3 inches of asphalt concrete over 6 inches of
Caltrans Class II aggregate base. If this portion of Jefferson Street is considered a collector street, we
would recommend a TI of 6.0 be used and a pavement section consisting of 4 inches of asphalt concrete
over 6 inches of Caltrans Class II aggregate base. We recommend that the geotechnical consultant re-
evaluate the pavement design, based on the R-value of the subgrade material exposed at the time of con-
struction. We recommend that the upper 12 inches of the subgrade be compacted to a relative
compaction of 95 or more percent of the maximum dry density as evaluated by ASTM D 1557-00. The
above pavement sections should provide an approximate pavement life of 20 years. If traffic loads are
different from those assumed, the pavement design should be re-evaluated.
If you have any questions regarding this letter, please call at your earliest convenience. We appreciate the
opportunity to be of service.
Sincerely,
Erik Olsen, G.E.
Chief Geotechnical Engineer
EO/Rlleo
Attachment: Laboratory Test
Distribution: (2) Addressee
IL all
Randal L. Irwin, C.E.G.
J Chief Engineering Geologist
57 10 Ruffin Road • San Diego, California 92123 • Phone (858) 576-1000 • Fax (858) 576-9600
San Diego • Irvine • Ontario • Los Angeles • Oakland • Las Vegas, • Salt Lake City • Phoenix
R-VALUE TEST RESULTS
SAMPLE LOCATION SAMPLE DEPTH SOIL TYPE RVALUE
C-i 0.5-2.0 Silty SAND 68
C-2 1.6-3.6 Silty SAND 71
PERFORMED IN GENERAL ACCORDANCE WITH ASTM 0 2544-94
I.fin,o I R-VALUE TEST RESULTS
I Jefferson Street North.
Carlsbad, California
( PROJECT NO. DATE 'iGURE
104669002 7/02 '., I
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