HomeMy WebLinkAbout3151; Palomar Airport Road; Palomar Airport Road; 1987-05-22( I
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Testing Engineers—San Diego
A Division ol United Stales Testir/g Company. Inc.
3467 Kurtz St., P.O. Box 80985, San Diego, Ca. 92138 (619) 225-9641
2956 Industry Street, Oceanside, California 92054 (619) 757-0248
City of Carlsbad
•Community Development
2075 Las Palmas Drive
Carlsbad, California 92008
Attention; Mr. Al Virgilio
May 22, 1987
Job No. 7092-1
RECElViiD
"f/iAY 2? 1937
MUNICIPAL PROJECTS
DIVISION
Subject; Supplementary Geotechnical Consulting Services
Palomar Airport Road
East of Paseo Del Norte
Carlsbad, California
Gentlemen:
This report presents results of our additional soil
investigation and pavement section design of the subject site.
The purpose of the soil investigation was to retain bulk soil
samples to be used in the laboratory for "R"^value tests. These
actual "R"-value test results were then used to estimate the
various pavement sections presented herewith.
Subsurface conditions were explored by drilling ten 8-inch
diameter test borings with a Mobile B-61 drill rig, to 4 to 20
feet depths. A staff geologist from our office was present
during the drilling of the test borings. The sample locations
and soil types with the respective "R"-value results are
presented in Table I.
316
Palomar Airport Road
East of Paseo Del Norte
Carlsbad, California
Page No. 2
May 22,. 1987
Job No. 7092-1
TABLE I
Bore
Hole No,
Bore
Hole
Location
Sample
Depth
Feet
Soil
Type R-Value
1 30+00 8 Sandy clay 12
2 32+50 13 Sandy clay 13
3 36+00 12-15 Sandy clay 9
4 36+00 18-20 Sandy clay 8
5 40+00 7 Gravelly
Refusal @ 7 ft.
6 42+00 7 Sandy clay 6
7 50+00 2-4 Silty sand 47
8 53+00 4-6 Clayey sand 21
9 72+50 5 Silty sand 57
10 85+00 . 6-8 Silty clay 27
CJ • • O
Palomar Airport Road Page No. 3
East of Paseo Del Norte May 22, 1987
Carlsbad, California Job No. 7092-1
ASPHALTIC CONCRETE DESIGN
Based on the R-value results and a T.I. value of 9 for primary
arterial, as required by the City of Carlsbad, alternate
structural sections are computed. For purposes of section
design, "R"-value results have been separated to represent three
zones of the alignment. The results are summarized and
presented on Table II.
The design assumes a minimum asphaltic concrete thickness of 6
inches and processed Class II aggregate base course. If the
three layer conventional system is preferred, we recommend
disintegrated granite (D.G.) with minimum "R"-value of 50 to be
used as select import for a subbase course.
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Palomar Airport Road Page No. 4
East of Paseo Del Norte May 22,. 1987
Carlsbad, California Job No. 7092-1
TABLE NO. II
RECOMMENDED SECTION DESIGN ALTERNATIVES
Materials are referenced to Cal Trans Standard Specifications
for aggregate subbase, aggregate base, and asphaltic concrete.
Zone 1: Station 27+00 to Station 32+50
Basement Soil R-Value 12
Traffic Index (Prime Arterial) 9
Minimum a.c. Thickness, ft. (inch) 0.5' (6")
Minimum cover required (GE) ft. (inch) 2.55
Alternative 1: Conventional 3 Layer System;
Actual Gravel
Equivalent (GE)
Course (Gf) Feet
Asphaltic Concrete 1.80 0.90
Class II Agg. Base 1.10 0.91
Agg. Subbase (R=50) 1.00 0.75
2.56
Thickness
Feet Inch
0.50 6
0.83 10
0.75 9
2.08 25
Alternative
0.50 6\
1.50 18 /
2.00 24/
Asphaltic Concrete 1.80
Class II Agg. Base 1.10
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Palomar Airport Road Page No. 5
East of Paseo Del Norte May 22,.1987
Carlsbad,.California Job No. 7092-1
Zone 2: Station 32+50 to Station 50+00
Basement Soil R-Value 6
Traffic Index (Prime Arterial) 9
Minimum a.c. Thickness, ft. (inch) 0.5' (6")
Minimum cover required (GE) ft. (inch) 2.70
Alternative 1: Conventional 3 Layer System;
Actual Gravel
Thickness Equivalent (GE)
Feet Inch Course (Gf) : Feet
0.50 6 Asphaltic Concrete 1.80 0.90
0.83 10 Class II Agg. Base 1.10 0.91
0.92 11 Agg. Subbase (R=50) 1.00 0.92
2.25 27 2.73
Alternative 2: Conventional 2 layer System;
0.50 6. Asphaltic Concrete 1.80 0.90
1.67 20 Class II Agg. Base 1.10 1.83
2.17 C2i^'' 2.73
Note: Based on the "R"-value results and
uniform soil type at Station 36+00, either of
the above asphaltic pavement sections can be
utilized at 17 feet road level. The "R"-value
shown on Table I should be verified after
grading.
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Palomar Airport Road
East of Paseo Del Norte
Carlsbad, California
Page No..6
May 22, 1987 '
Job No. 7092-1
Zone 3; Station"50+00 to Station 85+00
Basement Soil R-Value
Traffic Index (Prime Arterial)
Minimum a.c. Thickness, ft. (inch)
Minimum cover required (GE) ft. (inch)
21
9
0.5' (6")
2.28
Alternative 1; Conventional 3 Layer System:
Actual
Thickness
Feet Inch Course (Gf)
Gravel
Equivalent
Feet
(GE)
0.50 6 Asphaltic Concrete 1.80 0.90
0.50 6 Class II Agg. Base 1.10 0.55
0.83 10
1.83 22
Agg. Subbase (R=50) 1.00 0.83
2.28
Alternative lA;
Actual
Thickness
Feet Inch Course (Gf)
Gravel
Equivalent
Feet
(GE)
0.50 6 Asphaltic Concrete 1.80 0.90
0.83 10 Class II Agg. Base 1.10 0.91
0.50 6 Agg. Subbase (R=50) 1.00 0.50
1.83 22 2.31
Alternative 2: Conventional 2 layer System:
0.50 6 Asphaltic Concrete 1.80 0.90
1.25 15
1.75 21
Class II Agg. Base 1.10 1.38
2.28
Palomar Airport Road Page No. 7
East of Paseo Del Norte May 22, 1987
Carlsbad, California Job No. 7092-1
The samples taken are assumed to be representatives of the
material which will be immediately under the planned structural
section. The design is based on the lowest "R"-value for that
zone since it represents the lowest quality material
encountered.
The asphaltic pavement sections recommended reflect our best
estimate of the project requirements based on an evaluation of
the subsurface soil conditions encountered at the exploration
locations and the assumption that the soil conditions do not
deviate appreciably from those encountered.
Any unusual conditions, not covered in this report, encountered
during site development, should be brought to the attention of
the soil engineer. The "R"-value results should also be
verified before construction, so that modifications can be made
if necessary.
This office should be advised of any changes in the project
scope or proposed site grading so that it may be determined if
the recommendations contained herein are appropriate.
Palomar Airport Road
East of Paseo Del Norte
Carlsbad, California
Page No. 8
May 22, 1987
Job No. 7092-1
We appreciate the opportunity to be of service to you on this
project and look forward to a continued association on this and
future projects. If you have any questions, please do not
hesitate to contact our office.
Almaz FWS eha
Project Engineer
Respectfully submitted,
TESTING ENGINEERS-SAN DIEGO
1Thomas H. Chapman, RCE 34228
^ Vice President
THC/AF/eh
Addressee (2)
cc: Jay F. Olsen
Testing Engineers—San Diego
A Division ol United States Testing Company, Inc. •.
3467 Kurtz St., P.O. Box 80985, San Diego, Ca. 92138(619) 225-9641
2956 Industry Street, Oceanside, California 92054 (619) 757-0248
April 22, 1987
Job No. 7092
City of Carlsbad
Community Development
2075 Las Palmas Drive
Carlsbad, California 92008
Attention: Mr. Al Virgilio
Subject: Geotechnical Consulting
Clarification of Elements
Regarding Palomar Airport Road
Widening Report
Carlsbad, California
Referenced
Report:
"Geotechnical Consulting
Palomar Airport Road Widening
Carlsbad, California," by
Testing Engineers-San Diego,
dated March 3, 1987
Referenced
Letter:
"Geotechnical Consulting
Palomar Airport Road Widening,"
by Pountney and Associates, Inc.,
dated March 30, 1987
Palomar Airport Road Widening Page No. 2
Carlsbad, California April 22, 19817
Dear Mr. Virgilio:
This is in response to the referenced letter written by Pountney
& Associates, Incorporated regarding our report on the project.
During the process of study, limited contact was made between
Testing Engineers and the other company in discussing the items
to be considered, and its general format. As a result, Pountney
and Associates wrote the letter asking fbr clarification and the
following is discussed for each of the items:
SECTION 1.1
1. "The near surface, saturated, alluvial soil,
whenever encountered, should be removed to a
minimum depth of three feet" is a general
construction recommendation.
SECTION 1.2
2. "Soil adjacent to. the roadway should be
excavated and recompacted. The excavation
should extend to at least ten feet (10') from
the outside edges of the roadway". A roadway
is in this definition the pavement section,
from curb to curb. This excavation and
recompaction is intended to give lateral
support to the soil under the pavement, to
provide protection from erosion and reduce
water seepage, as explained in the report.
Palomar Airport Road Widening Page No.. 3
Carlsbad, California April 22, 1987
SECTION 1.3
3. The Benching requirement refers to downslope
fills.
SECTION 1.4
4. The soil removal is mentioned in the two
sections. Section 1.1 is refering to the
excavation of local pockets of soft and
saturated soils wherever encountered. Section
1.4 is referring to loose and/or compressible
existing top soil which is to be removed
uniformely. Unless the soil is saturated,
removal should be limited to two foot
thickness.
SECTION 1.8
5. Permanent cut and fill slopes should be
inclined at no steeper than 2 to 1 (horizontal
to vertical).
SECTION 2.2
6. In our rough draft of the report, two
alternatives including a retaining wall and a
crib wall were mentioned. Prior to issuance
of our final report, we deleted the crib wall
alternative without deleting the "above
alternatives".
SECTION 3.1
7. We understand there was no specific
requirement that the pavement be designed for
a Traffic Index (TI) value of 9. La Costa.
Avenue, another important project was designed
for a T.I. value of 8. So we assumed the same
for Palomar Airport Road.
Palomar Airport Road Widening Page No. 4
Carlsbad, California April 22, 1987
If TI of 9 is to be used, then an asphalt
concrete thickness and crushed aggregate base
of 6 inches and 15 inches, repectively, could
be used. The City of Carlsbad requires a
minimum section of 6 and 18 inches,
respectively.
A detour pavement section of 4 inches asphalt
concrete and 8 inches of aggregate base may be
used.
SECTION 3.2
8. This section was included because we
understand that grading would generate excess
material and we suggested that the clay be
exported and the on-site granular soil be used
in the roadway.
We had a discussion about all the above items with Mr. Jay F.
Olsen in our meeting on April 10, 1987 and have come to a better
understanding. In summary, we feel that the overall
recommendations in the report cover most of the necessary design
parameters as well as construction techniques. All of the above
questions could have been clarified easily with better
communication. We hope our contact will improve in the future.
Palomar Airport Road Widening Page No. 5
Carlsbad, California April 22, 1987
The opportunity to be of service is appreciated, and if you have
any additional questions regarding this project, please do not
hesitate to contact us at your convenience.
Respectfully submitted,
TESTING ENGINEERS-SAN DIEGO
Almaz FesTseha
Project Engineer
AF/eh
Addressee (2)