HomeMy WebLinkAbout3190; RANCHO SANTA FE RD; AS GRADED REPORT LA COSTA TOWN CENTER, RSF RD, LA COSTA AVE; 2004-04-20I SOIL TESTING, INC.
P H 0 N E P.O. Box 60062 (V
(619) 280-4321 San Diego, CA 92160-0627 I 0 280 Riverdale Street (877) 215-4321 a . A X San Diego, CA 92120
(619) 280-4717 www.scst.com
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V AS-GRADED V
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V GEOTECHNICAL REPORT
I . LA COSTA TOWN CENTER
RANCHO SANTA FE' ROAD- AND -
V V . LA COSTA AVENUE
I CARLp.AD; CALIFORNIA, -
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PREPARED FOR: s .
V V MR. JEFF JENCO
I V LUSARDI CONSTRUCTION
V 1570 LINDA VISTA DRIVE V
. SAN MARCOS, CALIFORNIA 92069
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.• . . V PREPARED BY:
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V V SOUTHERN CALIFORNIA SOIL & TESTING, INC.
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V . 6280 RIVERDALE STREET
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SAN DIEGO, CALIFORNIA 92120 V
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Providing Professional Engineering Seryicés Since 1959 V
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SECTION
TABLE OF CONTENTS
PAGE
1. SUMMARY OF OBSERVATION AND TESTING .......................................................................... 1 *
1.1. PROJECT DESCRIPTION ...... ...................................................... ......... ............................................ I
1.2. SITE PREPARATION ....................................
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.......................... . ........................... .......2 1.2.1. Grading Equipment .............................................................................................................2
1.2.2. .Clearing and Grubbing ............................................................................................................ 2
1:2.3. Site Grading .........................................................................................................................2
1.2:4. Keyways .................................................................................................................................... 3 1.2.5. Fill Slopes .................................... . ................................................................................. ........ 4 1.2.6. Cut Slopes ............
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....................................................................................................................... 4 1.2.7. StormDrain Trench Backfill ................................................................................... . ................ 4 1.2.8. Subdrain ....................... ............................................................................... . .......................... 4
1.3.. FIELD OBSERVATION AND TESTING ...................... . ................... . ................................................. ......5 I.A. LABORATORY TESTS ......................................................................................................................5
1.5. AS-BUILT GEOLOGY ...................................................................................................................
.1.6. REMAINING WORK .................... 6
CONCLUSIONS ............ . ...................................................................................... . ...................... 6
RECOMMENDATIONS ................................................. ................................................................. 7
3.1. FOUNDATIONS ................................................................................................................................ 7 3.1.1. General ..................................................................................... ........................................... 7 3.1.2., Reinforcement ........................................................................................................... . ............ 7 3.1.3. Seismic Design Factors..... ....... . ......... .... ............................... ............................................. .... 7 3.1.4. Foundation Excavation Ob'ervation ........................................... .........................................8 3.1.5... Settlement Characteristics ... .......... ....................................... . .................................................. 8 3.1.6. Expansion Characteristics ............................. . ...... . ..................... ........................................... 8 3.1.7. Foundation Plqn Review'............................... ............... ................. ............................................. 8 3.1.8. Soluble Sulfates ....................................................................................................................... 8
3.2. SLABS-ON-GRADE .................................
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. 3.2;1. Interior Concrete Slabs-on-Grade ....... ................... .................................................. ........... 8 3.2.2. . Extrior Concrete. Slabs-on-Grade. .................................... . ................................................... 9 3.3.. EARTH RETAINING WALLS ........ ..................................
.•......1.0 331 Foundations ..................... .. ...................................................................................................... 10 3.3.2. Passive Pressure .......................... . ........................................................................................ 10 3.3.3. Active Pressure........................................................ .......
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................................ ..................... 10 .3.3.4: Retaining Wall Subd rains and Waterproofing .................... .................................................. 10 3.3.5.. Backfill ................... ........................ ...................................................................................... 10 3.3.6. Factor of Safety.................................................................................................................
4. LIMITATIONS ................................................................................................................................ 11 •
'tSOIL & TESTING.
I April 20, 2004
I. Mr. Jeff Jenco.
Lusardi Construction
/ 1570 Linda Vista Drive
i San Marcos, California 92069
P H 0 N E l P.O. Box 600627
(619) 280-4321' I San Diego, CA 92160-0627
TOLL FREE
(877)215-4321 I 6280 Riverdale Street I
FAX I San Diego, CA 92120
(619) 280-4717 I www.scst.com
SCS&T No. 0411014
Report No. 4
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Subject: -AS-'GRADED GEOTECHNICAL REPORT I - LA COSTA TOWN CENTER
RANCHO SANTA FE 'ROAD,AND LA COSTA AVENUE -
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CARLSBAD, CALIFORNIA
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References: 1) "Existing Storm Drain, La Costa Town Center, Rancho Santa Fe and La Costa
Avenue, Carlsbad, California'; prepared by Southern California Soil and Testing,
Inc.; dated March' 12,'2004 (SCS&T 0411014-3).
"Fill Slope Construction, La Costa Town Center, Rancho Santa Fe and La Costa
Avenue, Carlsbad, California'; prepared by Southern California Soil and Testing, I . Inc.; dated January 20, 2004 (SCS&T 0411014-2).
"Preliminaiy Geotechnical Study Update, Parcels S. E. 13 and 25Acres Easterly
of La Costa Avenue and'Mission Estancia'; prepared by GeoSoils, Inc.; dated I . June 6, 1990. '
Dear Mr. Jenco:
In accordance with your request, this report has been prepared to present the 'results of field
I . observations and testing performed in conjunction with mass grading 'operations at the subject site.
Our services were performed between January 16 and March 19, 2004. The grading .was performed
by Erreca's of El Cajon, California. To assist in determining the locations and 'elevations of our field
I density tests, we were. provided with a set of plans prepared by O'Day Consultahts, dated
December 18, 2003, which define the general extent Of site grading.
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1. SUMMARY OF OBSERVATION AND TESTING
1.1. PROJECT DESCRIPTION' - - •
The project site is located about 1,000 feet to the northeast of the intersection of Rancho Santa Fe
Road and La Costa Avenue in Carlsbad, California. The site is bordered by the existing Rancho
Lusardi Construction ' April20, 2004 La Costa Town Center .' . SCS&TNo. 0411014-4
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Santa Fe Road to the northwest, the new alignment of Rancho Santa Fe Road (currently under
construction) to the south, and the recently completed Paseo Lupino to the east. The recent grading
'operations that are the subject of this report produced a street-graded configuration with drainage
directed toward a. catch basin near the west corner of the site.
The western portion of the site is -bordered by newly-constructed fill slopes up to about 40 feet in
height that descend to the existing and new Rancho Santa Fe Road alignments. The eastern
portion of the site is bordered by cut and fill-over-cut slopes ranging' up to about 25 feet in height,
descending to the new Rancho-Santa Fe Road and Paseo Lupino. All slopes were constructed at
2:1 (horizontal:vertical) ratio. Additional grading will be performed at a later date to achieve final
proposed grades. The 'site.will ultimately be developed with a, retail center, inclUding two' retail
structures and an asphalt parking lot.
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The sheet graded configuration of the site established by the recent mass grading-is depicted on
Plate No. 1 A. .The currently proposed site,developrnent scheme is depicted on Plate No. 1 B.
1.2. . SITE PREPARATION
1.2.1. 'Grading Equipment
The primary' equipment employed for the subject ,grading operations included:
2 -Caterpillar D10 Bulldozer 1 -Water truck . .
1 - Caterpillar 992 Loader', ' , 1 - Excavator
1 Caterpillar D9 Bulldozer' ' 3 - Caterpillar 773 Rock Trucks
I - Caterpillar D8 Bulldozer. . ...
1.2.2. Clearing and Grubbing
Site preparation began with the removal of existing vegetation and organic matter from the area,
to be graded. The detrimental material generated from this operation was exported from the
site.
1.2.3. Site Grading
Existing fill, topsoil and alluvial deposits were removed from the areas to receive proposed
settlement-sensitive improvements. The bottoms of ,the removal areas generally exposed
metavolcanic rock. Pre-existing fill soils associated with the existing and new alignments of
Rancho Santa Fe Road were left in place at the western end of the site. Temporary slopes were
cut intothe fill soils at a 1:1 ratio as removals were made. The fill exposed in the 1:1 slope was
benched as fill operations progressed. Removal depths ranged up to a maximum of about 25
feet'below existing grades. '. . .
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Up to about 55 feet of fill was placed to achieve proposed sheet-graded elevations in the
western portion of the site, while cuts of up to about 25 feet (including over-excavation) were
required in the eastern portion of the site. The proposed building pads were over-excavated to
minimum depths of approximately 5 feet below proposed finish floor elevations. Parking areas
were over-excavated to a minimum of approximately 10 feet below final parking, lot finish grade
elevations. .
Blasting was required to achieve the required cuts in the eastern portion of the site. Much of the
material produced by.blästi'ng consisted of rock fragments up to 2 feet in diameter with adequate
soil matrix material for placement as compacted fill. These rock/soil fills were typically moisture
conditioned and placed-in thedeep fi.11'aieas of the site (at least 10 feet below proposed grade)
in lift's of about 1.5 to 2.0 feet in thickness. Compaction was achieved primarily with rock trucks.
Soil matrix material was added in some cases to provide sufficientfines to fill voids between
rock fragments. Blasted material possessing only limited soil matrix material was generally
renoved and stockpiled in the designated stockpile area to the east of the new Rancho Santa
Fe Road alignment. Occasional boulders larger than 2 feet in diameter were placed within the.
compacted fills, individually or in wirrows,, under observation of SCS&T's soils technician
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Fill placed within the upper 5 feet of the building pads and the upper 10 feet of the parking lot
areas. consisted of select capping material. This material was comprised primarily of. silty
'sand/sandy silt with variable clay and rock fragments generally' not exceeding 6 inches in
rnaximurn' dimension, although occasional boulders larger than 6 inches maybe present. Similar
select soil material was also utilized as compacted fill within the outermost 6 feet of fill slopes.
The select material was obtained from on-site topsoil and alluvial deposits, as well as a borrow
site to the east of Rancho Santa Fe Road.
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Excavation bottoms were generally not scarified due to the rocky nature of the exposed material.
The soils generated frorn the removal operations, on-site cuts, and import fill from the borrow
site were placed in the removed areas as uniformly compacted fill material. Typically, fill soils
were placed in moisture conditioned lifts and compacted until field density tests indicated a
minimum of 90 percent relative compaction. Compaction was achieved primarily by means of a
Caterpillar 992 loader, rock trucks and other heavy construction equipment. This process
continued until designed elevations were reached.
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1.2.4. Keyways
To provide support for the proposed fill and fill-over-cut slopes, keyways were cut' Into dense
métavolcanic rock along the proposed toes Of the slopes. Th&keyways were generally at leat'
15 feet wide and slop'ed back into the existing sloping terrain at an approximate gradient of two
percent.
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1.2.5. Fill Slopes
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Fill and fill-over-cut slopes were constructed at several locations within the subject site. In order
to provide for a uniformly compacted -slope surface, the face of the slopes were track-walked
with a Caterpillar D8 bulldozer. Field density tests taken in the slope surface indicated at least
90 percent relative compaction. . . .
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1.26. Cut Slopes . . .
Cut slopes were observed by an SCS&T geologist and found to be free of significant adverse
geologic conditions. . . . . .
12.7. Storm Drain Trench Backfill .
- Three storm drains were installed for this project. Storm Drain A is located on site and Storm
Drains B and 'C are located east of the new Rancho Santa Fe Road in the borrow site. The
backfill soils for the storm drain trenches were tested by our firm for relative compaction. The
approximate locations of the trench backfill tests for Storm Drain A are noted on Plate No. 1k
The approximate locations of the trench backfill tests for Storm Drains B and Care noted on
Plate No. 2. The storm drain in-place density tests have been labeled "SD". Typically, the soils
generated from the borrow pit were used as backfill material. The backfill material was
compacted to at least 90 percentof maximum dry density determined in accordance with ASTM
D 1557-00 procedures. Compaction was achieved primarily by means of an excavator-mounted
sheepsfoot compaction wheel and other heavy, construction equipment.
1.2.8. Subdèain .
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Groundwater was encountered in the western corner of the subject site at the bottom of the
removal excavation. A subdrain was installed in. this area due to the presence'of the .groundwater. The subdrain- consisted of a 4-inch diameter perforated pipe (SDR735),
surrounded by about 6 cubic feet of crushed rock per lineal foot, wrapped in filter fabric. The
subdrain was connected to an existing storm drain inlet adjacent to the existing Rancho Santa
Fe Road. Approximately 12ieet of fill was placed,prior to construction of the subdrain to
maintain fall into the, storm. drainpipe. The approximate location. and flow line elevations of the
subdrain are indicated on Plate No. 1. s
An abandoned storm drain pipe was encountered in the narrow area at the northeastern corner
of the site. The eastern portion of the pipe was removed. The excavation resulting from the
removal was backfilled with compacted fill. In-place density tests indicated relative compaction
values of 90 percent or greater. The western portion of the storm drain was left in place because
it connected to a live storm drain box slightly to the southeast of existing Rancho Santa Fe
Road. It is our understanding that the southeast terminus of this segment wascapped with,
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concrete at the point where it exits the southeast-facing cut slope. SCS&T did not observe the
I.. capping of the pipe.
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1.3. FIELD OBSERVATION AND TESTING 0
I Field observations and density tests were performed by a represertative of SCS&T during the
grading operations. The density tests were performed according to ASTM D 2922701 (nuclear.
gauge) procedures. Rock corrections were applied as necessary as described in Section 1.4. In-
place density testing was- limited within the rock/soil fills due to excessive rock content. Where
testing was impractical, the fill was observed as it was placed and in potholes to verify.that sufficient
moisture content, 'soil matrix material and uniform compaction effort had been achieved. Test
locations are shown on Plate NOs. 1 and 2, while the test results are shown on Plate Nos. 3 through
6. The accuracy of the in-situ density test locations and elevations-is a.function of the accuracy of
. the survey control provided by others. Unless otherwise noted, their locations and elevations were
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determined by pacing and hand level methods and should be considered accurate only to the
1 .degree implied by the method. used.
As used herein, the term "observation" implies only that we-observed the progress of work we were
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. involved with, and performed field density tests, which in conjunction with our observations were the
- basis for our opinion as to whether the work was performed in substantial conformance with the
geotechnical recommendations and the requirements of the applicable agencies
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1.4. LABORATORY TESTS
Maximum dry density determinations were performed on representative samples of the soils used-in
the compacted fills according to ASTM D 1557-00, Procedure A and C. Procedure A is used wlen
the soil contains 20 percent or less by mass of material retained onthe #4 sieve. This procedure
1 .specifies that a 4-inch diameter cylindrical mold of 1/30 cubic foot volume be used and that the soil
- -tested be placed in 5 equal layers with each layer compacted by 25 blows utilizing a 10-pound
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. hammer with an 18-inch drop. Procedure C is used when the soil contains more than 20 percent by
weight of material. is retained on the 3/8-inch sieve and less than 30 percent by mass is retained on
the 3/4-inch sieve. This procedure specifies that a 6-inch diameter cylindrical mold of 1/13 cubic
I. foot volume be used and that the soil tested be placed in 5 equal layers with each layer compacted
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. by 56 blows utilizing a 10-pound hamther, with an 18-inch drop. The results of these tests, presented
on Plate No. 5, were used in 'conjunction with the'field density tests to determine the degree of
I - relative compaction of the compacted fill.'
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Rock corrections were, applied to the soil samples having not more than' 40 percent by weight
retained on the #4 sieve -or not more than 30 prcent by weight retained on the 3/4-inch sieve
- according to ASTM D 4718-87 (reapproved .1994) procedures. The results of these tests, as
Lusardi Construction April 20, 2004 La Costa Town Center : SCS&T No. 0411014-4
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presented on Plate No.. 5, were used in conjunction with the field density tests to determine the
degree of relative compaction of the compacted fill.
The expansion potential of the prevailing foundation soils was determined using UBC Test Method
18-2. The results of these tests, shown on Plate No. 5 indicate expansion potential ranging from
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medium to high. The recommendations contained herein reflect these conditions.
Results of soluble sulfate tests are.pending.
.. 1.5. AS-BUILT GEOLOGY
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Based on the results of on-site geOlogical observations, the following conclusions are presented:
' 1) The geOlogical conditions exposed atthe site were found to be similar.tô those described in
. . the referenced geotechnical repOrt(s). . .
- 2) Cut slopes were observed and found to be free of significant adverse geologic conditions..
3) All areas which were to receive fill were observed and found to be suitable for the
support of the proposed structural fill and settlement sensitive improvements.
4) To the best of our knowledge, the site is geologically suitable for the proposed
.. construction.
1.6. REMAINING WORK:-.. .- . .
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The following operations remain-to be completed. It is recommended that field observations and
relative compaction tests be performed during these operations to verify that they are performed in
\ accordance with job requirements and local grading ordinances.
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Placement of additional fill to achieve proposed grades;
Backfilling of underground utility trenches. . -
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CONCLUSIONS
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To the best of our knowledge based on our field observations and the in-place density test results,
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the subject grading was performed in substantial accordance with .the recommendations contained
. in the referenced geotechnical reports, the City of Carlsbad Grading Ordinance, and the Uniform.'
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Building Code
A site plan depicting the currently-proposed scheme for the future development of the subject site is
included herein as Plate No. 1 B. The, recommendations presented below are based upon this
development scheme. Any significant changes to- the development scheme should be reviewed by
SCS&T so that recommendations can be modified as necessary. In particular, it is noteworthy that
the building pad undercuts were designed to accommodate the specific building locations and finish
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floor elevations depicted on Plate No. 1B. Modifications to the locations or ele'iations of the
buildings may necessitate additional undercuts, including possible additional blasting.
3. RECOMMENDATIONS . .
3.1. FOUNDATIONS . . ..
3.1.1.General' . . .. . . .. .
Shallow foUndations'mày be utilized for the support of the proposed improvements. The
footings for the proposed structures should have a minimum depth of 24 inches below lowest
adjacent pad grade. Footings for exterior improvements such as retaining walls may have a
minimum depth.of 18 inches. A minimum width of 12 inches and 24 inches is reádfrvé?fdéd for
continuous and isolated footings, respectively. A bearing capacity of 2000 pounds per square
foot (psf)may be assumed for said footings; The bearing capacities maybe increased by 113
when considering wind or seismic forces. Footings adjacent to or within slopes should be
deepened such that a minimum horizontal distance of 7 feet existsbetween the bottom outside
footing edge and the face of the slope.. For retaining wall footings, the minimum distance should
be increased to 10 feet. . .
3.1.2. Reinforcement
Continuous footings should be reinforced with at least two No. 5bars positioned near the bottom
of the footing and at least two No. 5 bars positioned near the top of the footing.. This
reinforcement is based on. geotechnical considerations and is not intended to be in lieu of
reinforcement necessary to satisfy structural considerations.
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3.1.3. Seismic Design Factors
Based upon the 1997 edition of the Uniform Building Code, the following seismic design factors
are considered appropriate for the subject site.
Seismic Zone 4: Z=0.40
Source Fault: Rose Canyon Fault Zone 0
Seismic Source Type: B 0 0 0, 0 Soil Profile Type: .5c
0 Distance to Seismic Source: 11 kilometers 0
Near-Source" Factor N,=1.0-
Near-Source Factor N,=1.0 0 0 0
It is likely that the site will experience the effects of at least one moderate to large earthquake
during the life of the proposed structure.
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3.1.4. Foundation Excavation Observation
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It is recommended that all foundation excavations be approved by a representative from this
office prior to forming Or placing reinforcing steel. S
3.1 5. Settlement Characteristics
The anticipated total and differential settlements may be cohsidered to be within tolerable limits
provided the recommendations presented. in this report are followed. It should be recognized
that minor cracks normally occur in concrete slabs and foundations due to shrinkage during
curing or redistribution of stresses and some cracks may be anticipated. Such cracks are not
necessarily an indication of excessive vertical movements
3.1.6. Expansion Characteristics 0
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Expansion Index tests indicate expansion potentials ranging from medium to high. The
recommendations contained in this report reflect 'a highly expansive conditIon.
3.1.7. Foundation Plan Review
-. Foundation plans should.* hould be submitted to this office for review to ascertain that the
recommendations contained in this report are implemented and no revised recommendations
are necessary due to- changes in the development scheme.
3.1.8. Soluble Sulfates
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Soluble.sulf ate tests are .pending. Appropriate recommendations will be provided as necessary,
once results are available:
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32. SLABS-ON-GRADE
3.2.1. Interior Concrete. Slabs-on-Grade .
Concrete slabs-on-grade should have a minimum thickness of 5 inches and be reinforced with at
least No. 4 reinforcing bars placed at 18 inches onceflter each way. Slab reinforcement should
be placed approximately at mid-height of the slab and should extend. at least 12 inches into the
adjacent footings. Slab sunderlaihby retaining wall backfill should have a minimum thickness of
5 inches. In this case, minimum reinforcement should consist of No.4 bars placed at 18 inches
on center each way. Slabs-bn-gràde should be underlain by 4-inch thick blanket of clean,
poorly graded, coarse sand (sand equivalent = 30 or greater) or, crushed rock. This blanket
should consist of no more than 20 percent and 10 percent passing the #100 and #200 sieves,
respectively. Where moisture sensitive floor coverings are planned., vapor retardant should be
placed over the sand layer.' An -additional 2 inches of sand should be placed over the vapor
retardant'. Typically, visqueen is used as a vapor retardant. If visqueen is'used, a minimum 10-
mil is recommended. 0
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Itis our understanding that the moisture barrier described above will allow the transmission of 6.
to 12 pounds of moisture per 1000 square feet per day through the slabunder normal
conditions. Moisture emissions may vary widely depending upon, factors such. as concrete type
and subgrade moisture conditiOns. If this amount of. moisture is excessive, additional
I recommendations will be pro'iided by this office. It is recommended that moisture emission tests
be performed prior to the placement of floor coverings to ascertain whether moisture emission
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values are within the manufacturer's specifications. In addition, over-àtèring should be
avoided, and good site drainage should be established and maintained to prevent the build-up.of
excess sub-slab moisture..
- 1 3.2.2. Exterior Concrete Slabs-on-Grade
Exterior concrete slabs should have a minimum thickness of 4 inches and should be reinforced
I with at least No. 3 bars at '18 inches on center each way. All slabs should be provided with
weakened plane joints. Joints should be placed where cracks are anticipated to develop
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naturally, and should be in accordance with the American Concrete Institute (Ad) guidelines
Section 3.13. Alternative patterns consistent with ACI guidelines also can be used. The
landscape *,architect can be consulted in. selecting the final joint patterns to improve the
I aesfhetics of the concrete slabs-on-grade,
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A concrete mix with a 1-inch maximum aggregate size and a water/cement ratio of less than 0.6
is recommended for exterior slabs. A lower water content will decrease 'the potential for
(shrinkage cracks. 'It is strongly suggested .that the driveway concrete mix have a minimum
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, compressive strength of 3,000 'pounds per square inch. This suggestion is meant to address
early driveway use prior to full concrete curing. Both coarse and fine aggregate should conform
to the "Standard Specifications for Public Works Construction" ("Greenbook"), prepared by
,Public Works Standards, Inc.
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I It would be prudent to consult with a materials engineer regarding the review of the concrete mix
design,' and to retain 'a registered special inspector to observe the placement of concrete.
Special attention should be.paid tothe method of curing the concrete to reduce the potential for
excessive shrinkage and resultant randomcracking. It should be,recognized that minor cracks
I • occur normally (in concrete' slabs and foundations due to shrinkage
, during curing and
redistributiOn of stresses. Some shrinkage cracks should be expected and are not necessarily
an indication of excessive vertical movement or structural distress.
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I ' • Factors that contribute to the amount of shrinkage that takes 'place in a concrete slab include
joint spacing, depth, and design; concrete mix components; water/cement ratio and surface
finishing techniques According to the undated 'Technical Bulletin" published by the Southern
California Rock Products Association, and Southern "California 'Ready Mixed Concrete
Lusardi Construction April20, 2004 La Costa Tdwn Center SCS& T No. 0411014-4
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Association (see Appendix B), flàtwork formed of high-slump concrete (high water/cement ratio)
utilizing 3/8-inch maximum size aggregate ("Pea Gravel Grout" mix) is likely to exhibit extensive'
shrinkage and cracking. Cracks most often oàcur in random patterns between construction
joints.
EARTH RETAINING WALLS
3.3.1. Foundations
The recommendations presented in the foundation section of this repot are also applicable to
earth retaining structures. -' '•
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3.3.2. Passive Pressure
The passive pressure for retaining wall foundations extending into compacted fill soils may be
considered to be 300 psf per foot of depth, up to a maximum of 1500 psf. This pressure maybe
increased one-third for seismic' loading. The coefficient of frictibn for concrete to soil may be
assumed to be 0.25 for the resistance to lateral movement. When combining frictional and
passive resistance, the friction should be reduced by 1/3. The upper 12 inches'of soil should not
be considered when calculating passive pressures for exterior walls.
3.3.3. Active Pressure
The' active soil pressure for the design of unrestrained and restrained earth retaining structures
With level backfills may be assumed to be equivalent to'the presCure of a fluid weighing 35 and
55 pounds per cubic foot (pcf), respectively.' An additional 15 pcf should be added to the
aforementioned values for 2:1 (horizontal to. vertical) sloping. backfills. These pressures do not
consider any other surcharge- loads. If any are anticipated, this office should be contacted for
the necessary increase in soil pressure. These values also assume a granular and drained,
' backfill' condition.
3.3.4. Retaining Wall Subdrains and Waterproofing, ' S
Retaining wall subdrains should be intalled,in accordance with the detail presented on Plate"
No.7. Waterproofing specifications and details should be provided by the project architect. The
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- Waterproofing have been properly installed. ' •, ' ' '
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3.3.5. Backfill
All backfill soils should be compacted to at least 90 percent relative compaction. Expanive or
• clayey soils shoUld not be used for backfill material. Walls should not be backfilied until the
masonry has reached an adequate strength.
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3.3.6. Factor, of Safety
The above values, with the exception of the'ällowable soil bearing pressure, do not include a
factor of safety. Appropriate factors of safety should be incorporated into the design to prevent
walls from overturning and sliding.
4.' LIMITATIONS
This. report covers only the services performed between January 16-and March 19, 2004., Our
opinions presented herein are based on our observations and the relative compaction test results
and are limited by the scope of'the'services that we agreed to: perform. Our services were
performed in accordance with the currently accepted standard of practice, and in such a manner as
to provide a reasonable measuFe of the compliance of the grading and backfill operations with the
job- requirements. No warranty, express or implied, is given or-intended with respect to the services
which we have performed, and neither the performance of those services nor the submittal of this
report should be construed as 'relieving the contractor of the responsibility to'conform with the job
'requirements.
Our services were generally performed on an "on-call" basis. Therefore, the in-place density tests
performed by our field representative can only be construed as representative of the areas tested
which are shown on the attached plates.
Should you have any questions regarding the contents of this report, or if we, may, be of further
assistance, please contact our office at your convenience.
Respectfully submitted,
SOUTHERN CALIFORNIA SOIL AND TESTING, INC.
i( /L
Daniejp..f&, RCE:37 Michael P. Farr, CEG 1938
Vice Pesidert 4: ' , 'Senior Enineering Geologist
- -
DAB:MPF:sd.i.._'...-'., '
OF
(4) Addressee
(2) Aspen Properties, Attn: Mr. Wayne ,George