HomeMy WebLinkAboutCT 13-06; La Costa Villas Development; Geotechnical; 2014-09-09i
i
j SMS GEOTECnNICAL SOUITTONS. INC.
^ Consulting Geoteclmical Engineers & Geologists
^ 1645 S Rancho Santa Fe Rd, Suite 208, San Marcos, California 92078
^ 760-761-0799, smsgeosol.inc@gmad.com
^ C\ \3-
\ Project No. GI-9-14-18 ^ft^-^A
November 17, 2014
ACE Engineering
Mr. Mike Massodnia
1645 South Rancho Santa Fe Road, Suite 208
San Marcos, Califomia 92078
SoutheroProperty Margins HiIlsideToeRetainingWalls,Pr^ose^
401. Gibraltar Street At Jerez Court. Carlsbad. California (DWG 483-2A) " C?Cr
i We have received and reviewed the most recent comments from the city of Carlsbad reviewer and
» the revised wall designs (by ANP Engineering dated, November 15,2014) for the southem property
I marginshillsidetoeretainingwallwithaslopingbackfillcondition,proposedincormectio^
• project development. Based on our review and from a geotechnical pomt of view the following are
P appropriate:
? 1 An active lateral earth pressure of 50 pcf (EFP) should be considered for the sloping rear
• hillside condition behind the wall underlain by undisturbed sedimentarj' formational rocks
% (Td), as now used in the revised wall designs.
• 2 A seismic lateral inverted triangular earth pressure of 15H acting at 0.6H (H is the retained
• height) above the base ofthe wall is acceptable to us and may be considered as recommended
i» by Allied Earth Technoiogv (Page 10 ofreport dated June 5,2014, Project No. 13-1147H1).
H It is noteworthy that the subject rear hillside toe retaining walls are site retaimng walls (not
^ building walls) and retain less than 12 feet maximum.
• 3 The rear areas of the project site including the large ascending slope are underlain by
il " siltstone/sandstone formational rock units (Td). An allowable bearing pressure of2000 psf
S may be used for undisturbed competent formational rocks as specified m our report (Project
• No GI-9-14.18), dated September 9,2014. The net allowable bearing pressure can also be
|# increased for additional foot of depth(s) and width(s), and by Vz for short term wind and
1^ seismic loading to the maximum designated value, as specified.
• 4 Rear wall backcut excavations into the ascending hillside will expose natural
it siltstone/sandstone formational rocks (Td) with their engineering properties conside^d^m
~ Page 1 of 2 ICI^A--fi^«
^ DEC 112
^ • "'•-^ ^ ^ •*
the lateral active soil pressure determination. Additional excavations into the ascending
hillside for replacing the natural and competent siltstone/sandstone formational rock
exposures within the wall active zone with select sandy granular soils are not warranted, nor
necessary for rear slope toe retaining walls.
We appreciate this opportunity to be of service to you. If you have any questions or need
clarification, please do not hesitate to contact the undersigned. Reference to our Project No. GI-9-
14-18 will help to expedite our response to your inquiries.
SMS Geotechnical solutions, Inc.
itfl 2835 :ehdi S. Shariat
GE#2885
Distribution: Addressee (1, e-mail)
MBM Development, Mr. Majid Mortazavi (2, e-mail)
ANP Engineering, Mr. Pirouz Etemad (e-mail)
CCH Design Group, Charles Heincy (e-mail)
m m
:
SMS tSEOTECHNICAL SOLUTIONS. livr.
Page 2 of 2
SMS GEOTECHNICAL SOLUTIONS. INC
Consulting Geotechnical Engineers & Geologists
1645 S. Ranciio Santa Fe Rd, Suite 208, San Marcos, California 92078
760-76]-0799, smsgeosol.inc@gmail.com
OX I'h'
Project No. GI-9-14-18 jr> w
October 16,2014 ^^VP^
ACE Engmeering ^
Mr. Mike Massodnia '^?\//^'^
1645 South Rancho Santa Fe Road, Suite 208 ^%^/^ii^'^'*yc/W
San Marcos, Califomia 92078 '^fr^ '
Geotechnical Grading Plan Review And Response to City Review, Proposed La Costa Villas
Development, Lot 401, Gibraltar Street At Jerez Court, Carlsbad, California (DWG 483-2A)
We have received and reviewed the most recent Grading Flans for the proposed 8-iinit La Costa
Villas development at the above-referenced Lot 401 (DWG-483-2A). We have also received and
reviewed the City of Carlsbad review comments of our report entitled "Addendum Geotechnical Flan
Review Update, Proposed La Costa Villas Development, Gibraltar Street At Jerez Court, Carlsbad,
California," Project No. GI-9-14-18, dated September 9,2014.
The purpose of this effort was to review the project grading plans for Lot 401 (DWG-483-2A) from
a geotechnical engineering viewpoint, and provide further information and/or clarifications to the
review comments raised by the City of Carlsbad. Based on our review, the following review
comments, clarifications and additional information are appropriate:
I« Grading Plan Review
Based on our review, the project most current grading plans present a feasible design and is
considered acceptable from a geotechnical viewpoint. All site development, grading and
earthwork recommendations presented in the project soils and geotechnical reports (see report
dated September 9,2014 for a list of pertinent reports and documents) remain valid and should
be considered in the project designs and implemented during the construction phase except
where amended or superseded below.
K- Response to The City Comments
In general, we agree with the city reviewer regarding the total overall wall heights. The
referenced report (dated September 9,2014) refers to the exposed (above ground) wall heights,
while the city reviewer considers the total wall height including the embedded portions beiow
Page 1 of 2
the ground surface necessary to satisfy minimum setback requirements to daylight (sloping
down ground conditions at the toe). The embedded wall portion may be considered in designs
as apart ofthe overall height receiving frill active pressures, as we understand it is the case in this
project.. Aitemative design methods may considered the embedded wall portion as a part of wall
foundations receiving reduced active pressures below the ground surface and fiili active pressures
above the ground surface in conjunction with reduced bearing pressure and reduced passive
resistance due to sloping down ground surface at the toe ofthe wall.
Considering the wall design methodology and modeling, the design wall heights for this project
should be considered as the total heights including the embedded portions below the ground
surfaces, as indicated by the city reviewer.
in. LIMITATIONS
This geotechnical plan review is not a "Plan Check Review" and does not relieve the responsibility
of the project design consultant(s) and contractor(s) to get completely familiarized with the
requirements ofthe project soil report(s) and fiilly incorporate its recommendations into the project
design, plans and construction works, where appropriate, and as applicable. Our review and
comments are for general geotechnical conformance of the project plans with the intent ofthe project
soil report and design recommendations. Review of structural and civil engineering calculations,
architectural intent and structural and civil engineering design modeling and basis, verification of
set back requirements, easements and right-of-ways, as well as code, city and county compliance are
beyond geotechnical engineering services. It is the owner's or his (her) representative's
responsibility to provided copies ofall pertinent soil report(s), updates, addendum letters and plan
review letters to respective design consultant(s), and general contractor and his (her) subcontractor(s)
for full compliance.
We appreciate this opportunity to be of service to you. If you have any questions or need
clarification, please do not hesitate to contact the undersigned. Reference to our Project No. GI-9-
14-18 will help to expedite our response to your inquiries.
S>^ehdi S. Shariat
GE #2885 Si
Distribution: Addressee (1, e-mail) ^^^^^
MBM Development, Mr. Majid M^teSwPt^^ e-mail)
ANP Engineering, Mr. Pirouz Etemad (e-mail)
SMS GEOTECHNICAL SOLVriO.^S. INC
Page 2 of 2
SMS GEOTECHNICAL SOLUTIONS, INC
Consulting Geotechnical Engineers & Geologists
Value Engineering
1645 S. Rancho Santa Fe Road, Suite 208, San Marcos, California 92078
Office: 760-761-0799
Cell: 760-331-8738
smsgeosol. inc@gmail. com
Project No. GI-9-14-18
September 9,2014
ACE Engineering
Mr. Mike Massodnia
1645 South Rancho Santa Fe Road, Suite 208
San Marcos, Califomia 92078
Addendum Geotechnical Plan Review Update, Proposed La Costa Villas Development,
Gibraltar Street At Jerez Court, Carkbad, Califomia ( V 13 -
Pursuant to your request, SMS Geotechnical Solutions, Inc. has completed the follovsdng Addendum
Geotechnical Plan Review Update report for the proposed La Costa Villas development at the above-
referenced property. This letter also serves as our verification that SMS Geotechnical Solutions, Inc,
is now retained as the Geotechnical Engineer of Record (GER) for the above-referenced project. The
undersigned has prior work history on the project while employed at Vinje & Middleton
Engineering, Inc. in 2004, as noted in the references below.
The project property is also designated as Lots 399,400 and 401 of La Costa South Unit No. 5. The
approximate site coordinates are 33.086°N latitude and -117.2475°W longitude.
Project development Plans are available and were reviewed as a part of this effort. Surface and
subsurface geotechnical conditions at the project property were previously studied by prior
consultants who issued the following technical reports outlining their fmdings and recommendations:
1. "Second Update of Preliminary geotechnical bivestigation Update Report, Proposed Multi-
Unit Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, California," prepared by
Allied Earth Technology, Project No. 13-1147H1, dated June 5,2014.
2. "Update of Preliminary Geotechnical Investigation Update Report, Proposed Multi-Unit
Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, California," prepared by Allied
Earth Technology, Project No. 13-1147H1, dated October 10,2013.
3. "Preliminary Geotechnical Investigation Update Report, Proposed Multi-Unit Attached
Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad," prepared by Vinje &
Middleton Engineering, Inc., Job #04-287-P, dated July 7,2004. This report was completed
under the engineering supervision of the undersigned while employed at the Vinje &
Middleton Engineering, Inc.
ACE Engineering
Mr. Mike Massodnia
September 9,2014
Page 2
4. "Preliminary Soil and Geotechnical Investigation, Graded Hillside Property, Gibraltar Street
Near Jerez Court, La Costa Area of Carlsbad, San Diego County, California," Prepared by
MV Engineering, Inc., Job #1017-91, dated Febmary 20,1991.
The referenced reports were reviewed in connection with this effort and copies can be provided upon
request.
Based on the project available plans and reports. Lot 399 is a cut lot underlain mostly by Terrace
Deposits, while Lots 400 and 401 are transition lots with filled ground in the northem frontage areas
and formational bedrock cut surfaces in the southem rear areas. The purpose of this transmittal was
to review the referenced reports and confinn compatibility of the project most cmrent Grading Plans
with the site indicated geotechnical conditions. Revised and/or amended recommendations
consistent with the attached plans, current applicable codes and engineering standards are also
provided in the following sections, and will supplement or superseded those given in the referenced
reports.
Based on our review ofthe referenced reports and project grading plans, development ofthe project
properties for multi-unit attached residential dwelling purposes, substantially as proposed, is feasible
from a geotechnical viewpoint. Geotechnical conditions reported in the referenced reports remain
unchanged. All conclusions and recommendations provided in the referenced reports also remain
valid and should be incorporated into the final designs and implemented during the constmction
phase except where specifically superseded or amended below.
1. Based on our review of the project plans, the southem perimeter site retaining wails are on
the order of 6 feet high maximum, while north-south running site retaining walls separating
individual pads along the east and west sides are minor features less than 3 feet high
maximum. Building basement type retaining walls, parallel and adjacent to the site perimeter
retaining walls, are on the order of 10 feet high maximum, will replace slope conditions and
enlarge tewaced pads upon constmction, where they occur.
2. Adequate setback or deepened foundations shall be required for all foundations constracted
on or near the top of descending slopes to maintain minimum horizontal distances to daylight
or adjacent slope face, as specified. There should be a minimum of 7 feet or one-third ofthe
slope height, whichever is more, horizontal setback from the bottom outside edge ofthe
footing to daylight. The temporary transition slopes wall be removed and replaced with
building basement type retaining walls during the course of project development. The
recommended foundation setback requirement vvdll also provide for a safe fiiture temporary
wall backcut excavation, necessary for the adjacent lower building wall constmction.
ACE Engineering
Mr. Mike Massodnia
September 9,2014
Page 3
3 Based on our review of the project plans, the upper site retaining walls (3 feet high
maximum) appear to maintain adequate set backs with sufficient embedment depths avoiding
surcharging ofthe lower building basement type retaining walls. In general, a downward
projected 1:1 line from edge of the upper wall foundations should not intercept the lower
building basement type wall.
4. The following soil design parameters are based on the available strength tests completed by
others on representative samples of onsite earth deposits and our review of referenced reports:
* Design active soil pressure for retaining stractures = 35 pcf (EFP), level backflll,
cantilever, unrestrained walls.
* Design active soil pressure for retaining stractures = 50 pcf (EFP), 2:1 sloping backfill,
cantilever, unrestrained walls.
* Design at-rest soil pressure for retaining stmctures = 53 pcf (EFP), non-yielding,
restrained walls.
* Design passive soil resistance for retaining stractures = 350 pcf (EFP), level surface at the
toe, compacted fills, soil mass extends 10 feet or 3 times the height of the surface
generating passive resistance.
* Design passive soil pressure for retaining stmctures = 420 pcf (EFP), level surface at the
toe, competent undisturbed bedrock, soil mass extends 10 feet or 3 times the height ofthe
surface generating passive resistance.
* Design coefficient of friction for concrete on compacted fills = 0.35.
* Design coefficient of fiiction for concrete on competent undisturbed bedrock = 0.40.
* Net allowable foundation pressure (minimum 12 inches wide embedded at least 12 inches
into compacted fills) = 1500 psf
* Net allowable foundation pressure (minimum 12 inches embedded at least 12 mches into
imderiying competent undisturbed bedrock) = 2000 psf
Notes;
- An additional seismic force due to seismic increment of earth pressure should aiso be
considered in the project wall designs for building walls with greater than 6-feet soil
differential on each side or retaining walls 12 feet or taller, as appropriate. A seismic
lateral inverted triangular earth pressure of 24 pcf (EFP) acting at 0.6H (H is fhe retained
height) above the base ofthe wall should be considered, where applicable. The seismic
lateral earth pressure should be considered in addition to the specified static earth and
surcharge (due to nearby foundation) pressures.
- When combining passive pressure and fiictional resistance, the passive component should
be reduced by one-third.
ACE Engineering
Mr. Mike Massodnia
September 9,2014
Page 4
- The net allowable foundation pressure provided herein, was detennined for footings
having a minimum width of 12 inches embedded at least 12 inches into the underlying
compacted fills or competent undisturbed bedrock, as approved in the field. The indicated
value may be increased by 20% for each additional foot of depth and 10% for each
additional foot of width to a maximum of 3500 psf for compacted fills and 4500 psf for
undisturbed competent bedrock, if needed. The allowable foundation pressures provided
herein also apply to dead plus live loads and may be increased by one-third for wind and
seismic loading.
LIMITATIONS
The conclusions and recommendations provided herein have been based on all available data
obtained from the review of pertinent geotechnical documents as well as our experience with the
soils and bedrock materials located in the general site areas.
Of necessity we must assume a certain degree of continuity between available exploratory
excavations and/or natural exposures reported bu previous consultants. It is necessaiy, therefore, that
all observations, conclusions, and recommendations are verified during the grading operation. In
the event discrepancies are noted, we should be contacted immediately so that an inspection can be
made and additional recommendations issued if required. The recommendations made in this report
are applicable to the site at the time this report was prepared. It is the responsibility of the
owner/developer to ensure that these recommendations are carried out in the field.
It is almost impossible to predict with certainty the future performance of a property. The fiiture
behavior ofthe site is also dependent on numerous unpredictable variables, such as earthquakes,
rainfall, and on-site drainage pattems.
The fum of SMS Geotechnical Solutions, Inc., shall not be held responsible for changes to the
physical conditions of the property such as addition of fill soils, added cut slopes, or changing
drainage pattems which occur without our inspection or control.
The property owner(s) should be aware that the development of cracks in all concrete surfaces such
as floor slabs and exterior stucco is associated with normal concrete shrinkage during the curing
process. These features depend chiefly upon the condition of concrete and weather conditions at the
time of constraction and do not reflect detrimental ground movement. Hairiine stucco cracks will
often develop at window/door comers, and floor surface cracks up to Ve-inch wide in 20 feet may
develop as a result of nonnal concrete shrinkage (according to the American Concrete Institute).
ACE Engineering
Mr. Mike Massodnia
September 9,2014
Page 5
This report is issued with the imderstanding that fhe owner or his representative is responsible for
ensuring that the information and recommendations are provided to the project architect/stractural
engineer so that they can be incorporated into the plans. Necessary steps shall be taken to ensure that
the project general contractor and subcontractors carry out such recommendations during
constmction.
The project geotechnical engineer should be provided the opportunity for a general review ofthe
projects final design plans and specifications in order to ensure that the recommendations provided
in this report are properly interpreted and implemented. The project geotechnical engineer should
also be provided the opportunity to field verify the foimdations prior to placing concrete. If fhe
project soil engineer is not provided the opportunity of making these reviews, he can assume no
responsibility for misinterpretation of his recommendations.
This report should be considered valid for a period of one year and is subject to review by our firm
following that time. In case of plan revisions including changes in the final pad size, graded
embankments, actual building and improvement locations, lines and grades, and final elevations, this
report should be reviewed and updated by this office for review comments and additional
recommendations based on the plan changes, as appropriate.
We appreciate this opportunity to be of service to you. If you have any questions or need
clarification, please do not hesitate to contact the imdersigned. Reference to our Project No. GI-9-
14-18 vfill help to expedite our response to your inquiries.
SMS Geotechnical Solutions, Inc.
Distribution: Addressee (2, e-mail) '"^'C^CA^^
MBM Development, Mr. M^dMortazavi (2, e-mail)
ANP Engineering, Mr. Pirouz Etemad
SMS GEOTECHNICAL SOLUTIONS, JNC
Consulting Geotechnical Engineers & Geologists
VALUE ENGINEERING
ALLIED EARTH TECHNOLOGY
7915 SILVERTON AVENUE, SUITE 317
SAN DIEGO, CALIFORNIA 92126
PH. (858) 586-1665 FAX (858) 586-1660
(619)447-4747
ROBERT CHAN, P.E.
SECOND UPDATE OF
"PRELIMINARY GEOTECHNICAL INVESTIGATION UPDATE REPORT
PROPOSED MULTI-UNIT ATTACHED DWELLINGS
GIBRALTAR STREET AT JEREZ COURT
LA COSTA, CALIFORNIA
FOR
ACE CIVIL ENGINEERING
PROJECT NO. 13-1147H1
JUNE 5,2014
ALLIED EARTH TECHNOLOGY
7915 SILVERTON AVENUE, SUITE 317
SAN DIEGO, CALIFORNIA 92126
PH. (858) 586-1665 FAX (858) 586-1660
(619)447-4747
ROBERT CHAN, P.E.
June 5, 2014
Ace Civil Engineering
7668 El Camino Real #104-463
Carlsbad, CA. 92009
Attn : Mr. Mike Massoodnia
Subject: Project No. 13-1147H1
Second Update of "Preliminary Geotechnical Investigation Update
Report"
Proposed Multi-Unit Attached Dwellings
Gibraltar Street at Jerez Court
La Costa, Califomia
Dear Mr. Massoodnia:
In accordance •with your request, we have performed geotechnical engineering
i
' services for subject property, more specifically referred to as being Lot Nos. 399 to 401,
inclusive. La Costa South Unit No. 5, in the City of La Costa, State of Califomia.
The purpose of our work is to prepare an update report with current
geotechnical recommendations for the site development as presently proposed. The
scope of our work includes two visits to the site, and a review of the following plans and
documents:
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 2
Gibraltar Street
"Preliminary Soil and Geotechnical Investigation, Graded Hillside Project,
Gibraltar Street near Jerez Court, La Costa area of Carisbad, San Diego County,
Califomia" prepared by MV Engineering, Inc. (Their Job #1017-91, dated
Febmary 20, 1991.)
"Preliminary Geotechnical Investigation Update Report - Proposed Multi-Unit
Attached Dwellings, Gibraltar Street at Jerez Court, La Costa, Carlsbad" prepared
by MV Engineering, Inc. (Their Job #04-287-P, dated July 7,2004).
"Update of Preliminary Geotechnical Investigation Update Report -
Proposed Multi-Unit Attached Dwellings, Gibraltar Street at Jerez Court, La
Costa, Carlsbad" prepared by Allied Earth Technology, dated October 10,
2013.
"Site Grading Plan for La Costa Villas" prepared by ACE Civil
Engineering of Carlsbad, dated May 27,2014.
PROPOSED DEVELOPMENT
It is our understandmg that the site is to be developed to receive 26 townhomes
units. Nine units each will be constracted on Lot Nos. 399 and 400; and eight units on
Lot No. 401. The proposed stmctures will consist of two stories above a two-car garage,
and will be of wood-frame/stucco and slab-on-grade constmction.
FIELD INSPECTION
Inspections of the property on September 24, October 7, 2013, and May 23,2014,
indicate that the site was found to be generally of the same condition when rough grading
was completed in fiie early part of 1970, with the following exception :
A high combined cut/fill slope on the order of 70 feet in maximum was observed
along the rear, south end of the property, ascending to the residential lots to the south.
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 3
Gibraltar Street
This combined cut/fill slope has a slope rafio of 1 '/2: I (horizontal: vertical), with two
drainage ditches at mid-height.
This combined cut/fill slope has been in existence since the early1970's. The
upper portions of this slope, which are within the properties to south, are well maintained
and in good condition. The lower portions ofthe existing high cut/fill slope, which are
wdthin subject property has suffered some erosion and sloughing, due to lack of
maintenance over the decades. The erosion and sloughing were caused by overflow of
surface ranoff from the drainage ditches on the slope, which were had been filled with
debris and vegetation through the decades.
A review ofthe subdivision grading plan indicates that Lot 399 consists of all
cut or natural soils. Lot 400 is a "transition lot", with a maximum of 3 feet of fill soils
along the front portion of the site. Lot 401 is also a "transition lof, with a maximum of
7 feet of fill soils along the front ofthe property.
The fill soils encountered on the property site were derived locally, and consist of
a mixture of light brovra/light gray/dark brown sandy clay, clayey sands and silty sands.
These soils possess low to high expansion potential (Expansion Index of 46 and 98).
SITE GEOLOGY
Reviews of Califomia DMG open-file report 96-02 and CGS geologic map ofthe
Oceanside quadrangle indicate that the property is underiain by two formations : the
ProjectNo. 13-1147H1 Ace Civil Engineering 06/05/14 Page 4
Gibraltar Street
Santiago Formation, and Quatemary terrace deposits per the Department of Mine and
Geology report, or Quatemary Old alluvium, per the Califomia Geologic Survey map.
Both types of Quatemary units are mapped equivalently.
As described in open-file report 96-02, the Santiago Formation is middle Eocene
in age (approximately 49 to 45 million years old). It consists primarily of fine to
medium-grained sandstone interbedded with siltstone and claystone, and localized
coarse-grained sandstone and conglomerate. Bedding attitudes in the Santiago Formation
generally dips westward 5 degrees.
The terrace/alluvium deposits are younger, late to middle Pleistocene
(approximately 1.8 to 1 million years old). They are reddish brown, poorly bedded and
poorly to moderately indurated sandstone, siltstone and conglomerate.
GEOLOGIC HAZARDS
Earthquake Fault Rupture Hazard
San Diego's tectonic setting includes north and northwest striking fault zones, the
most prominent and active of which is the Rose Canyon Fault Zone. Other fault zones lie
in eastem and northem San Diego County.
Fault rapture hazard would affect a property if an active fault trace or traces
traverse the property. The subject property lies approximately 7 miles east of the
offshore Newport-Inglewood Rose Canyon fault zone and 20 miles east of the
offshore Coronado Banks fault zone. The property is approximately 28 miles west of the
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 5
Gibraltar Street
Elsinore fault zone, 57 miles west of the San Jacinto fault zone, and 82 miles west of the
San Andreas fault zone.
The property is outside any State and City designated fault and fault hazard zones
and is therefore not subject to a special fault investigation.
The Rose Canyon Fault Zone is capable of generating a 6.9 magmitude
earthquake. Even though direct ground mpture from faulting directly underneath the
subject property is unlikely, the property will be subjected to considerable
ground acceleration and shaking from an earthquake event along the nearby faults. The
intensity of ground shaking is dependent on distance from faults, earthquake magnitude
and duration, and seismic characteristics of foundation soils and bedrock.
Soil Liquefaction
It is our opinion that due to the relatively high density of the competent natural
and compacted fill soils (after remedial grading recommended herein) prevalent at the
site; the lack of near-surface groundwater and the grain size characteristics of the in-situ
soils, the risk for seismically induced soil liquefaction is very low.
FINDINGS, CONCLUSIONS AND RECOMMENDATIONS
In general, we concur and agree with the findings, conclusions and recommen-
dations presented in the above-mentioned Report and Update, and said fmdings,
conclusions and recommendations are still valid and applicable for the proposed site
development.
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 6
Gibraltar Street
The following addendum recommendations are made, however, as supplement to
the recommendations presented in the subject Report and Update. If there are
discrepancies, the addendum recommendations herein will prevail.
Expansiveness of On-site Near Surface Soils
1. Some of the near-surface soils encountered on the site possess high expansion
potential (Expansion Index = 98).
Earthwork
2. The current grading plans for the project were reviewed. The three building
pads will remain in their current elevations. Prior to commencement of grading,
it is recommended that the site be cleared and grabbed, and all debris and
vegetatiori disposed of offsite.
3. It is recommended that existing fill soils along the front of Lot Nos. 400 and 401
be removed. Maximum depths of fill on these lots are on the order of 3 to 7 feet.
The bottom of the over-excavation should be inspected by our firm, and scarified
to a depth of 12 inches. The removed soils should then be properiy moistened,
and uniformly recompacted to at least 90 percent of maximum dry density in
accordance with A.S.T.M. D1557, until finished grade is achieved..
4. For Lot No. 401, it is recommended that the upper soils below finished grade be
scarified to a depth of 12 inches, properiy moistened and uniformly to at least 90
percent of maximum dry density in accordance with ASTM D1557. All footings
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 7
Gibraltar Street
are to be extended into the underlying competent formation soils or bedrock.
5. Since the maximum depth of fill soils on Lot No. 400 is only 3 feet, and extends
over a relatively small area, it is recommended that the footings of the proposed
stracture be extended through the compacted fill soils at least 12 inches into the
underlying competent formational soils.
6. The upper, surface and near-surface soils on the building pads had been subjected
to weathering for decades. It is recommended that the natural soils on Lot Nos.
399 and 400 be scarified to a depth of 12 inches, properly moistened and
uniformly compacted to at least 90 percent of maximum dry density, in order to
provide adequate support to the concrete slab of the proposed stmctures.
Repair of Surficial Slope Failure
7. It is recommended that the soils loosened by the erosion and sloughing of the
existing slope be removed. The building pads along the toe of the existing
slope will be widened, excavating and removing the loosened soils. A retaining
wall will also be constracted along the bottom of the existing slope.
8. As th^repair work progresses up the existing slope, benches will have to be
provided. The interval and width of the benches required will be determined by
our field personnel during the remedial grading.
9. The surface of the slope should be properly compacted with a sheepsfoot roller.
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 8
Gibraltar Street
In order to fiirther minimize the potential for future surficial slumping, it is
recommended that the slope be planted with deep rooted ground cover and shmbs
at 10 feet on center.
Foundation and Slab
10. It is recommended that a safe allowable soil bearing value of 1,500 pounds per
square foot be used in the design and checking of continuous or spread footings
that are a minimum of 15 and 24 inches in minimum horizontal dimension,
respectively, and are embedded at least 24 inches into the competent natural or
compacted filled ground.
11. The above safe allowable soil bearing value may be fiirther increased by one third
when considering wind and/or seismic forces.
12. The concrete slab for the proposed stractures should be at least 4 '/a inches net in
thickness, and be reinforced with a minimum of #3 rebars at 18 inches on center
in both directions, placed at mid-height of concrete slab. The concrete slab
should be underlain by 4 inches of clean sand and a vapor barrier in moisture
sensitive areas.
13. The continuous footings should be reinforced v^dth a minimum of 4 #5 rebars; two
rebars located near the top, and the other two rebars near the bottom of the
footings. Isolated pier footings should be reinforced with 2 #5 rebars in both
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 9
Gibraltar Street
directions, placed near the bottom of the footings. Please note that the above slab
and foundation reinforcements are based on soil characteristics only, and should
be superceded by the requirements of the project architect or stractural engineer.
14. It is recommended that the moisture content of the subgrade soils beneath the
proposed stmctures be maintained at approximately 120% of optimum moisture
content. However, no flooding of the foundation soils is permitted immediately
prior to the placement of concrete.
15. It is recommended that the foundation for the proposed stmcture be setback at
least 7 feet back from the top ofthe fill slope. Foundations placed closer to the
top of the slope than 7 feet should be deepened such that the outer edge of the
footing along the bottom is at least 7 feet back from the face of slope at that level.
For footings subject to lateral forces, such as those of a retaining wall, the above
setback should be increased to 10 feet.
16. It is further recommended that the foundation trench excavations be inspected by
our firm prior to the placement of concrete. Any loose and/or unsuitable soils
encountered should be removed and/or replaced under our direction.
Retaining Wall Design
1-7. It is recommended that retaining walls be designed to withstand the pressure
exerted by equivalent fluid weights given on the follovsdng page :
ProjectNo. 13-1147H1 Ace Civil Engineering 06/05/14 Page 10
Gibraltar Street
Equivalent
Backfill Fluid
Surface Pressure
(horizontal: vertical) (pcf)
Level 35
2:1 50
1 Vz : 1 58
The above values assume that the retaining walls are unrestrained from
movement, and have a granular backfill. For retaining walls restrained from
movement at the top, such as basement retaining walls, an uniform horizontal
pressure of 7H (where H is the height of the retaining wall in feet) should be
applied in addition to the active pressures recommended above.
18. All retaining walls should be supplied with a backfill drainage system adequate to
prevent the buildup of hydrostatic pressure. The subdrain should consist of one-
inch gravel and a perforated pipe near the bottom of the retaining wall. The width
of this subdrain should be at least 12 inches, and extend at least 2/3 height of the
retaining wall. The subdrain should be enclosed in a geotextile fabric such as
Mirafi MON or equal.
Seismic Earth Pressure
19. Seismic earth pressures can be taken as an inverted triangular distribution with
a maximum pressure at the top equal to 15H pounds per square foot (with H being
the height ofthe retained earth in feet. This pressure is in addition to the static
design wall load. Hie allowable passive pressure and bearing capacity can be
Project No. 13-1147H1 Ace Civil Engineering 06/05/14 Page 11
Gibraltar Sfreet
increased by 1/3 in determining the stability of the wall. A factor-of-safety of 1.2
can be used in determining the stability of the retaining wall under seismic
conditions.
Lateral Loading
20. To resist lateral loads, it is recommended that the pressure exerted by an
equivalent fluid weight of 350 pcf be used for footings or shear keys poured neat
against competent natural or compacted fill soils. The upper 12 inches of material
in areas not protected by floor slabs or pavements should not be included in the
design for passive resistance. This value assumes that the horizontal distance of
the soil mass extends at least 10 feet or three times the height ofthe surface
generating the passive pressure, whichever is greater.
21. A coefficient of sliding friction of 0.35 may be used for cast-in-place concrete on
competent natural or compacted fill soils. Footings can be designed to resist
lateral loads by using a combination of sliding fiiction and passive resistance.
The coefficient of friction should be applied to dead load forces only.
22. All backflll soils behind the retaining wall should consist of soils having low
expansion potential (Expansion Index < 50), and be compacted at least 90 percent
of maximum dry density .
Seismic Coefficients
23. The seismic design factors were determined in accordance with the 2010
ProjectNo. 13-1147H1 Ace Civil Engineering 06/05/14 Page 12
Gibraltar Street
Califomia Building Code, and presented below
Site Coordinates: Latitude 33.0860
Longitude 117.2475
Site Class: D
Site Coefficient Fa 1.040
Site Coefficient Fv 1.565
Specfral Response Acceleration
At Short Periods Ss 1.153
Spectral Response Acceleration
At 1-second Period Sl 0.435
Sms = FaSs 1.200
Smi = FvSl 0.681
Sds = 2/3*Sms 0.800
Sdi = 2/3*Sml 0.454
Preiiminarv Structural Pavement Section Design
23. For preliminary design purposes, it is recommended that a stmctural pavement
section of 3 inches of asphaltic concrete over 6 inches of Class II base material
over compacted subgrade be used.
I 24. The upper 8 inches of subgrade and base material should be compacted to at least
95 percent of maximum dry density.
25. For PCC pavement sections, it is recommended that the pavement section be 5 Vz
inches in thickness, and be reinforced with #3 rebars at 18 inches on center in
both directions, placed at mid-height of concrete slab. Control joints at 12-foot
intervals should also be provided.
ProjectNo. 13-1147HI Ace Civil Engineering 06/05/14 Page 13
Gibraltar Street
Utilitv Trench Backfill
26. It is recommended that any backfill soils placed in utility trenches located within
5 feet of any improvements and deeper than 12 inches, or backfill placed in any
trench located 5 feet out or more from a building and deeper than 5 feet, be
compacted to at least 90 percent of maximum dry density.
Surface Drainage and Lot Maintenance
27. Adequate drainage control and proper maintenance of all drainage facilities are
imperative to minimize infiltration of surface water into the underiying soil mass
in order to reduce settlement potential and to minimize erosion. The building pad
should have drainage swales which direct storm and excess irrigation water away
from the stracture and into the street gutters or other drainage facilities. No
surface runoff should be allowed to pond adjacent to the foundation of stractures.
Concrete Flatwork
28. It is recommended that concrete flatwork be 3 Vi inches in thickness and
reinforced with 6 x6-10/10 welded wire fabric placed at mid-height of slab. One-
i
i
inch expansion joints should be provided at 15-foot intervals; with Vi inch
weakened plane contraction joints at 5-foot intervals.
LIMITATIONS
The opinions and recommendations presented in this report are based upon surficial
observations and logical projections inferred from observed conditions and the
assumption that the soil conditions do not deviate appreciably from those encountered.
Should conditions vary from those presented herein be encountered during the
developmental constmction phase, this firm should be notified immediately so that a
qualified soil engineer can inspect the site conditions and evaluate the potential effects
and present recommendations.
ProjectNo. 13-1147H1 Ace Civil Engineering
Gibraltar Street
06/05/14 Page 14
This report has been prepared in accordance with generally accepted standards of
geotechnical engineering practice at the time of its preparation. No other warranties,
expressed or implied, are made as to the professional consultation and recommendations
contained herein. This report is provided for the exclusive use of the client or his
authorij
Ko.C-24613 ]
Preliminary Geotechnical Investigation
Update Report
Proposed IViulti-Unit Attached Dwellings
Gibralter Street at Jerez Court
La Costa. tlt'ffcOPY
July 7, 2004
Prepared For:
MR. ALVIN WASHINGTON
6479 Paseo Cerro
Carlsbad, California 92009.
Prepared By:
VINJE & MIDDLETON ENGINEERINO, INC.
2450 Vineyard Avenue, Suite 102
Escondido, California i92029
Job #04-287-P
ViNTE &: MIDDLETON ENGINEERING, INC,
Job #04-287.P
July?, 2004
2450 Vineyard Avenue
Escondido. Cilifornia 92029-1229
Phone (760) 743-1214
Fax (760) 739-0343
Mr. Alvin Washington
6479 Paseo Cerro
Carlsbad, California 92009
PRELIMINARY GEOTECHNICAL INVESTIGATION UPDATE REPORT, PROPOSED MULTI-
UNIT ATTACHED DWELLINGS, GIBRALTER STREET, JEREZ COURT, LA COSTA,
CARLSBAD, CALIFORNIA '
Pursuant to your request, Vinje and Middleton Engineering, Inc., has completed the
Preliminary Geotechnical Investigation Report for the subject site.
The following update report summarizes results of our research and review of pertinent
geotechnical reports and documents, current field reconnaissance, and provides
conclusions and recommendations for the proposed development as understood. From
a geotechnical engineering standpoint, it Is our opinion that the site is suitable for the
support of planned multi-unit development and associated improvements provided the
recommendations presented in this report are incorporated into the design and
construction of the project.
The conclusions and recommendations provided in this study are consistent with the site
geotechnical conditions and are intended to aid in preparation of finai development plans
and allow more accurate estimates of development costs.
If you have any questions or need clarification, please do not hesitate to contact this office.
Reference to our Job #04-287-P will help to expedite our response to your inquiries.
We appreciate this opportunity to be of service to you.
VINJE & MIDDLETON ENGINEERING, INC.
Dennis Middleton
CEG #980
DM/jt
•1
TABLE OF CONTENTS
PAGE NO.
I. INTRODUCTION 1
II. PROPOSED DEVELOPMENT 1
III. CONCLUSIONS 1
IV. RECOMMENDATIONS 2
A. Remedial Grading and Earthworks 2
B. Foundations and Slab-on-Grade Floors 8
C. Exterior Concrete / Flatwork 10
p. Soli Design Parameters 11
E. Asphalt and PCC Pavement Design 12
F. General Recommendations .... ^ 13
VIM. LIMITATIONS 16
PLATE NO.
Regional Index Map > 1
Site Plan 2
Retaining Wall Drain Detail 3
Isolation Joints and Re-entrant Corner Reinforcement ,.. 4
Preliminary Soil and Geotechnical Investigation Report APPENDIX A
Graded Hillside Project, Gibraltar Street, near Jerez Court
La Costa, Carlsbad, San Diego County
PROPOSED MULTI-UNIT ATTACHED RESIDENTIAL DWELLINGS
GIBRALTER STREET, JEREZ COURT
LA COSTA, CALIFORNIA
I. INTRODUCTION
The purpose of this report is to update our "Preliminary Soil and Geotechnical
Investigation, Graded Hillside Project, Gibraltar Street, Jerez Court, La Costa, San Diego
County, California," dated February 20,1991. Our efforts in this regard included a detailed
review ofthe referenced report and most recent plans in addition to a site visit conducted
by bur Engineering Geologist. The study property location is shown on a Regional Index
Map enclosed with this report as Plate 1. The referenced report has been reviewed in
connection with this work and a copy of the report is inciuded as Appendix A.
II. PROPOSgP DEVELOPMENT
The scope ofthe planned new development is comparable to the proposed development
addressed in the referenced Geotechnical Investigation. Current plans submitted to us
depict multi-unit attached residential dwellings, extensive retaining walls, and associated
improvements. A copy of the most current Site Plan is enclosed herein as Plate 2.
III. CONCLUSIONS
The site remains substantially unchanged from the original geotechnical investigation and
subsequent referenced report.
Based on our review of drawings made available to us, and from a geotechnical
engineering point of view, the proposed development is in substantial compliance with the
referenced report. The conclusions and recommendations put forth in that report remain
valid and should be implemented during the construction phase except where superceded
in the following sections.
The following comments are also appropriate and should be considered and/or
incorporated into the final plans where appropriate and applicable:
* All grading should be conducted per the referenced Geotechnical Investigation.
The Geotechnical Investigation report should be considered as a part ofthe project
foundation plans.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 2
GIBRALTER STREET, JEREZ COURT. LA COSTA JULY 7, 2004
* All grading operations including removals, suitability of earth deposits used as
compacted fill, and compaction procedures shouid be continuously inspected and
tested by the project geotechnical consultant and presented in the final as-graded
compaction report. The nature of finished subgrade soils should also be confirmed
in the final compaction report at the completion of grading.
* Final foundation plans may also be reviewed by the project geotechnical consultant
for conformance with the requirements ofthe referenced geotechnical investigation
report. More specific recommendations may be necessary and should be given
when final grading and architectural/structural drawings are available.
IV. RECOMMENDATIONS
The following recommendations are consistent with the indicated geotechnical conditions
at the project site and should be reflected on the final plans and implemented during the
construction phase. All following recommendations, where applicable, supercede those
put forth in the previous report. Added or modified recommendations may also be
appropriate and can be provided at the plan review phase when final plans are available:
A. Remedial Grading and Earthworks
Cut-fill and remedial grading techniques should be used in order to achieve final
design grades and improve soil conditions beneath the new structures and
improvements. All ground preparations and project construction should be
completed in accordance with the Appendix Chapter 33 of the Uniform Building
Code, City of Carlsbad Grading Ordinances, the Standard Specifications for Public
Works Construction, and the requirements of the foiiowing sections:
1. Clearing and Grubbing: Existing vegetation, deleterious materials and debris
should be removed from areas to receive new fills, structures, and
improvements plus 10 feet where possible, or as directed in the field. The
prepared ground should be inspected and approved by the project geotechnical
engineer, or his designated field representative prior to remedial grading work.
Abandoned pipes and utility lines should be properly removed and replaced, or
plugged as approved in the field. Voids created by removals ofthe abandoned
underground pipes and structures should be properly backfilled in accordance
with the requirements of this report.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido. California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 3
GIBRALTER STREET. JEREZ COURT. LA COSTA JULY 7, 2004
2. Non-uniform Bearing Soil Transitioning: Non-uniform ground transition from
excavated cut to placed fill should not be permitted underneath the proposed
structures and improvements. Building foundations, floor slabs, improvements,
and retaining wall foundations should be supported entirely on compacted fills
or founded entirely on competent undisturbed cut ground. Transition pads will
require special treatment. The cut portion of the cut-fill pads.plus 10 feet
should be undercut to a sufficient depth to provide fpr a minimum of 3 feet of
compacted fill mat below rough finish grades or at least 12 Jnches of compacted
fill beneath the deepest footing whichever is more. In the roadways, driveway,
parking and on-grade slabs/improvement transition areas there should be a
minimum of 12 inches of compacted soils below rough finish subgrade.
3. Fill Materials and Compaction: Soils generated from on-site removals and
over-excavations will predominantly consist of poor to marginal quality plastic,
moisture sensitive clay-rich deposits. Plastic clayey soils typically require
additional processing, mixing and moisture conditioning efforts in order to
manufacture a unifornn homogeneous mixture suitable for reuse as new
compacted fills.
Project fill soils should be clean deposits free of roots, stumps, vegetation,
deleterious matter, trash, and unsuitable materials as approved by the project
geotechnical consultant.
Unifomi bearing soil conditions should be constructed at the site by the
remedial grading and earthwork operations. Site soils should be adequately
processed, thoroughly mixed, moisture conditioned to 3% to 5% above the
optimum moisture levels or as directed in the field, placed in thin uniform
horizontal lifts and mechanically compacted to a minimum of 90% of the
corresponding laboratory maximum dry density per ASTM D-1557, unless
otherwise specified.
Fill soils placed within areas subject to potential flood inundation should be
mechanically compacted to a minimum of 90% of the laboratory maximum dry
density (ASTM D-1557). Slope protection and erosion control facilities should
be installed as shown on the approved civil drawings.
4. Capping and Select Grading: Final bearing and subgrade soil mixture at the
completion of remedial grading is anticipated to consist of moisture sensitive
potentially expansive deposits with detrimental affects which will require
geotechnical and structural mitigation designs as provided in the following
sections. Select grading and capping ofthe site may also be considered which
will allow more conventional foundations/slab and paving designs. In this case,
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 4
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
the upper 3 feet in the building envelope plus 10 feet, and upper VA feet in the
paving and improvement areas plus 3 feet should be capped with non-
expansive to very low expansive sandy granular import soils (expansion index
less than 21) compacted as specified herein.
Import sandy soils should also be considered for the project wall backfills.
Import soils should be inspected, tested as necessary and approved by the
project geotechnical consultant prior to the delivery to the site.
In the event only the building envelope plus 10 feet is capped with non-
expansive to very low expansive sandy import soils within the upper 3 feet, a
subsurface drainage system consisting of a minimum 2 feet deep by 2 feet wide
trench with 4 inches diameter perforated pipe (SDR 35) surrounded with %-inch
crushed rocks and wrapped in filter fabric (Mirafi 140 N) installed below the
capping soils, will be required as directed in the field.
5. Permanent Graded Slopes: Project graded slopes should be programmed
for 2:1 gradients maximum. Graded fill slopes constructed at 2:1 gradients will
be grossly stable with respect to deep seated and surficial failures for the
anticipated design maximum vertical heights. Graded cut slopes should be
reconstructed as stabilization fill slopes to develop stable embankments, or
retaining walls may be constructed at the toe of the graded cut slope for
additional support,
All fill slopes shall be provided with a lower keyway. The keyway for the
building pad fill slopes should maintain a minimum depth of 10 feet into the
competent bedrock units with a minimum width of 20 feet as approved by the
project geotechnical engineer or his designated representative. The keyway
should expose competent bedrock units throughout with the bottom heeled
back a minimum of 2% into the natural hillside, and inspected and approved by
the project geotechnical engineer. Additional level benches should be
constructed into the.natural hillside as the fill slope construction progresses.
Initial keyway development into the competent and stable formational units
should be inspected and approved by the project engineering geologist prior to
any fill placement. Locally deeper keyway depths should be anticipated.
The keyway for the driveway fill slopes should maintain a minimum depth of 3
feet into the firm native ground with a minimum width of 12 feet as approved by
the project geotechnical engineer or his designated representative. Bottom of
keyway stabilization by placing Geogrid earth reinforcement may also be
necessary and should be anticipated.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, CaIiforni,i 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 5
GIBRALTER STREET. JEREZ COURT, LA COSTA JULY 7, 2004
Fill slopes should also be compacted to 90% (minimum) of the laboratory
standard out to the slope face. Over-building and cutting back to the
compacted core, or backrolling at a minimum of 3 feet vertical increments and
"track-walking" at the completion of grading is recommended for site fill slope
construction. Geotechnical engineering inspections and testing will be
necessary to confirm adequate compaction levels within the fill slope face.
6. Temporary Construction Slopes: Unsupported temporary construction
slopes necessary during the removals, over-excavations and wall constructions
within the project existing fills, topsoil, terrace deposits, highly weathered and
friable formational units should be laid back at 1:1 or flatter gradients as
directed in the field. Elsewhere, temporary slopes less than 10 feet high
maximum developed within the on-site competent formational units may be
constructed at near vertical within the lower 3 feet and laid back at Yz.l
gradients within the upper portions. Trenching within the site upper soils or
weathered friable formational units may be laid back at 2:1 gradients or
provided with temporary shoring support. The new fill wall backfill should be
tightly keyed-in and benched into the temporary slopes as the filling/backfilling
progresses.
Temporary shoring support will also be required for all vertical trenches greater
than 3 feet unless othenwise approved by the project geotechnical consultant.
Any continuous shoring technique which can allow safe and stable excavations
may be considered provided it is approved by the owner or his designated
project consultants.
Minor sloughing of the temporary slope face may occur requiring maintenance
or cleanup. All temporary construction slopes require continuous geotechnical
inspections during the grading and wall construction operations. Additional
recommendations including revised slope gradients, setbacks and the need for
additional shoring support should be given at that time as necessary. The
project contractor shall also obtain appropriate permits, as needed, and
conform to Cal-Osha and local governing agencies requirements for
trenching/open excavations and safety of the workmen during construction.
7. Wall Back Drainage System: All site retaining walls should be provided with
an adequate back drainage system. The wall back drain system should consist
of a minimum 18 inches wide trench excavated to the depths of the wall
foundation level. A minimum 4-inch diameter, Schedule 40 (SDR 35)
perforated pipe surrounded with a minimum of 2.26 cubic feet per foot of
crushed rocks wrapped in filter fabric (Mirafi 140 N), or Caltrans Class 2
permeable aggregate should be used. The perforated drain pipe should be
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, Cahforni.i 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 6
GIBRALTER STREET. JEREZ COURT. LA COSTA JULY 7, 2004
installed at suitable elevations to allow for adequate fall via a non-perforated
solid pipe to an approved outlet. Filter fabric can be eliminated if Class 2
permeable material is used. A typical wall back drain system is depicted on the
enclosed Plate 3. Appropriate waterproofing should be provided behind the
walls. Protect pipe outlet as necessary.
8. Surface Drainage and Erosion Control: A critical element to the continued
stability of the graded building pads is an adequate surface and storm water
drainage control, and the installation of drainage control facilities. This can
most effectively be achieved by appropriate vegetation cover and the
installation of the following systems:
* Periods of prolonged rains can result in flowing surface water within the
swale area of the study site. Storm water and erosion control facilities
should be Installed per approved plans.
* Drainage swales should be provided at the top and toe of the graded slopes
per project civil engineer design.
* Building pad surface run-off should be collected and directed away from the
planned buildings and improvements to a selected location in a controlled
manner. Area drains should be installed.
* The finished slope should be planted soon after completion of grading.
Unprotected slope faces will be subject to severe erosion and should not be
allowed. Over-watering ofthe slope faces should also not be allowed. Only
the amount of water to sustain vegetation should be provided.
* Temporary erosion control facilities and silt fences should be installed during
the construction phase periods and until landscaping is fully established as
indicated and specified on the approved project grading/erosion plans.
9. Engineering Inspections: All grading operations including removals,
suitability of earth deposits used as compacted fills, and compaction
procedures should be continuously inspected and tested by the project
geotechnical consultant and presented in the final as-graded compaction
report. The nature of finished subgrade soils should also be confirmed in the
final compaction report at the completion of remedial grading.
Geotechnical engineering inspections shall include but not limited to the
following:
ViNjB & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 7
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
* Initial Inspection - After the grading/brushing limits have been staked but
before grading/brushing starts,
* Bottom of over-excavation inspection - After the natural ground or competent
|-| formational rock is exposed and prepared to receive fill but before fill is
I placed.
* Excavation inspection - After the excavation is started but before the vertical
depth of excavation is more than 5 feet. Local and Cal-Osha safety
requirements for open excavations apply.
* Fill/backfill inspection - After the fill/backfill placement is started but before
the vertical height of fill/backfill exceeds 2 feet, A minimum of one test shall
be required for each 100 lineal feet maximum with the exception of wall
backfills where a minimum of one test shall be required for each 25 lineal
feet maximum. Wall backfills shall also be mechanically compacted to at
least 90% compaction levels unless othenA/ise specified. Finish rough and
final pad grade tests shall be required regardless of fill thickness.
* Foundation trench inspection - After the foundation trench excavations but
before steel placement.
* Foundation bearing/slab subgrade soils inspection - Prior to the placement
of concrete for proper moisture and specified compaction levels.
* Foundation/slab steel inspection - After steel placement is completed but
before the scheduled concrete pour.
* Subdrain/wall back drain inspection - After the trench excavations but during
the actual placement. All material shall conform to the project material
specifications and approved by the project soils engineer.
* Underground utility/plumbing trench inspection - After the trench excavation,
but before placement of bedding or installation of the underground facilities.
Local and Cal-Osha safety requirements for open excavations apply.
Inspection of pipe bedding may also be required by the project geotechnical
engineer.
* Underground utility/plumbing trench backfill inspection - After the backfill
placement is started above the pipe zone but before the vertical height of
backfill exceeds 2 feet. Testing of the backfill within the pipe zone may also
be required by the governing agencies. Pipe bedding and backfill materials
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 8
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7. 2004
shall conform to the governing agencies requirements and project soils
report if applicable. All trench backfills shall be mechanically compacted to
a minimum of 90% compaction levels unless otherwise specified. Plumbing
trenches over 12 inches deep maximum under the interior floor slabs should
also be mechanically compacted and tested for a minimum of 90%
compaction levels.
* Pavement/improvements subgrade and basegrade inspections - Prior to the
placement of concrete or asphalt for proper moisture and specified
compaction levels,
B. Foundations and Slab-on-Grade Floors
The following recommendations and geotechnical mitigation are consistent with
clay to sandy silty clay (CH/CL), medium to high expansion potential (expansion
index less than 131) foundation bearing soil anticipated at finish grade levels.
Added or modified recommendations may also be necessary and should be given
at the time of the foundation plan review phase. All foundations and floor slab
recommendations should be further confirmed and/or revised as necessary at the
completion of rough grading based on the actual expansion characteristics of the
foundation bearing and subgrade soils. In the event capping of the building pad
with non-expansive to very expansive import soils are considered, this office should
be notified to provide appropriate revised foundations/slab recommendations:
1. Continuous interior and exterior foundations should be sized at least 15 inches
wide and 24 inches deep for single-story and two-story structures. Exterior
spread pad footings, if any, should be at least 30 inches square and 18 inches
deep and structurally tied to the perimeter strip footings with tie beams at least
in one direction. Tie beams should be at least 12 inches wide by 12 inches
deep. Footing depths are measured from the lowest adjacent ground surface,
not including the sand/gravel beneath floor slabs.
Exterior continuous footings should enclose the entire building perimeter.
Flagpole footings also need to be tied together if the footing depth is less than
4 feet below the rough finish grades.
2. Continuous interior and exterior foundations should be reinforced with a
minimum of four-#6 reinforcing bars. Place 2-#6 bars 3 inches above the
bottom ofthe footing and 2-#5 bars 3 inches below the top of the footing. Tie
beams should also be reinforced with 2-#4 bars top and bottom and #3 ties at
, VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, Cahfomia 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 9
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
24 inches on center maximum. Reinforcement details for spread pad footings
should be provided by the project architect/structural engineer.
3. The slab subgrade and foundation bearing soils should not be allowed to dry
prior to pouring the concrete or additional ground preparations, moisture re-
conditioning, and pre-saturation will be necessary as directed in the field.
The required moisture content ofthe bearing soils is apprqximately 3% to 5%
over the optimum moisture content to the depth of 24 inches below slab
subgrade. Attempts should be made to maintain as-graded moisture contents
in order to preclude the need for pre-saturation of the subgrade and bearing
soils.
4. In the case of pre-saturation of the slab subgrade and/or non-monolithic pour
(two-pour) system, dowel the slab to the footings using #4 reinforcing bars
spaced 18 inches on center and extending at least 20 inches into the footing
and 20 inches into slab. The dowels should be placed mid-height in the slab.
Alternate the dowels each way for ali interior footings.
5. After the footings are dug and cleaned, place the reinforcing steel and dowels,
and pour the footings.
6. This office should be notified to inspect the foundation trenches and reinforcing
prior to pouring the concrete.
7. Once the concrete for the footings has cured and underground utilities tested,
place 4 inches of %-inch rock over the slab subgrade. Flood with water to the
top of the 3/6-inch rock, and allow the slab subgrade to soak until moisture
testing Indicates that the required moisture content is present. After the slab
subgrade soils have soaked, notify this office and schedule for appropriate
moisture testing.
8. When the required moisture content has been achieved, place a 10-mil plastic
moisture barrier over the %-inch rock, and place 2 inches of clean sand (SE 30
or greater) on top of the plastic.
If sufficient moisture is present, flooding/pre-saturation will not be required. The
dowels may be deleted, and slab underlayment may consist of 2 inches of
clean sand over a 6 mil-plastic moisture barrier over 2 inches of clean sand,
and the footings and slab may be poured monolithically.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, Cahfomia 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 10
GIBRALTER STREET. JEREZ COURT, LA COSTA JULY 7, 2004
This office should be notified to inspect the sand, slab thickness, and
reinforcing prior to the concrete pour.
9. All interior slabs should be a minimum of 5 inches in thickness reinforced with
#4 reinforcing bars spaced 18 inches on center each way, placed VA inches
below the top of the slab.
10. Interior slabs should be provided with "softcut" contraction/control joints
consisting of sawcuts spaced 10 feet on center maximum each way. Cut as
soon as the slab will support the weight of the saw, and operate without
disturbing the tinal tinish which is normally within 2 hours after final finish at
each control joint location or 150 psi to 800 psi. The softcuts should be a
minimum of %-inch in depth but should not exceed 1-inch deep maximum.
Anti-ravel skid plates should be used and replaced with each blade to avoid
spalling and raveling. Avoid wheeled equipment across cuts for at least 24
hours.
11. Provide re-entrant corner reinforcement for all interior slabs. Re-entrant corners
will depend on slab geometry and/or interior column locations. Plate 4 may be
used as a general guideline.
12. Foundation trenches and slab subgrade soils should be inspected and tested
for proper moisture and specified compaction levels and approved by the
project geotechnical consultant prior to the placement of concrete.
C. Exterior Concrete / Flatwork
1. All exterior slabs (walkways, patios) should be a minimum of 4 inches in
thickness, reinforced with #3 bars at 18 inches on centers in both directions
placed 1 inches below the top of slab. Use 6 inches of 90% compacted clean
sand beneath all exterior slabs.
2. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on
center (not to exceed 12 feet maximum) each way. Tool or cut as soon as the
slab will support weight and can be operated without disturbing the final tinish
which is normally within 2 hours after tinal tinish at each control joint location
or 150 psi to 800 psi. Tool or softcuts should be a minimum of %-inch but
should not exceed 1-inch deep maximum. In case of softcut joints, anti-ravel
skid plates should be used and replaced with each blade to avoid spalling and
raveling. Avoid wheeled equipments across cuts for at least 24 hours.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
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PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 11
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
3. It is recommended to provide a minimum of 8 inches wide by 12 inches deep
thickened edge reinforced with a minimum of 1-#4 continuous bar near the
bottom along the free-ends of all exterior slabs and flatworks supported on
moisture sensitive expansive soils.
4. All exterior slab designs should be contirmed in the final as-graded compaction
report.
5. Subgrade soils should be tested for proper moisture and specified compaction
levels and approved by the project geotechnical consultant prior to the
placement of concrete.
D. Soil Desiqn Parameters
The following soil design parameters are based on tested representative samples
of on-site selected sandy materials. Potentially expansive plastic clayey soils
should not be used for wall backfill soils. All parameters should be re-evaluated
when the characteristics ofthe final soils have been specifically determined:
* Design wet density of soil = 119.0 pcf.
* Design angle of internal friction of soil = 34 degrees.
* Design active soil pressure for retaining structures = 34 pcf (EFP), level backfill,
cantilever, unrestrained walls.
* Design at-rest soil pressure for retaining structures = 53 pcf (EFP), non-
yielding, restrained walls.
* Design passive soil pressure for retaining structures = 421 pcf (EFP), level
surface at the toe.
* Design coefficient of friction for concrete on soil = 0.35.
* Net allowable foundation pressure for certified compacted fill = 1500 psf
(minimum 15-inch wide by 24-inch deep footings).
* Allowable lateral bearing pressure (all structures except retaining walls) for
certified compacted fills = 100 psf/ft.
Notes:
* Good quaiity sandy import soils may be considered for site wall backfill
purposes which will improve the above specified design parameters. Import
soils for wall backfill will require additional laboratory testing.
* Use a minimum safety factor of 1.5 for wall over-turning and sliding stability.
However, because large movements must take place before maximum passive
resistance can be developed, a minimum safety factor of 2 may be considered
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
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PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 12
GIBRALTER STREET. JEREZ COURT. LA COSTA JULY 7, 2004
for sliding stability particularly where sensitive structures and improvements are
planned near or on top of retaining walls.
* When combining passive pressure and frictional resistance the passive
component should be reduced by one-third.
* The net allowable bearing pressure provided herein was determined for
footings having a minimum width of 15 inches and depth of 24 inches. The
indicated value may be increased by 20% for each additional foot of depth and
5% for each additional foot of width to a maximum of 3500 psf. The allowable
foundation pressures provided herein also apply to dead plus live loads and
may be increased by one-third for wind and seismic loading.
* The lateral bearing earth pressure may be increased by the amount of
designated value for each additional foot of depth to a maximum of 1500
pounds per square foot.
E. Asphalt and PCC Pavement Desiqn
Specific pavement designs can best be provided at the completion of rough
grading based on R-value tests ofthe actual finish subgrade soils; however, the
following structural sections may be considered for cost estimating purposes only
(not for construction):
1. A minimum section of 3 inches asphalt on 6 inches Caltrans Class 2 aggregate
base may be considered for on-site asphalt paving surfaces not within the
public or private street right-of-way.
Base materials should be compacted to a minimum of 95% of the
corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath
the asphalt paving surfaces should also be compacted to a minimum of 95%
ofthe corresponding maximum dry density within the upper 12 inches.
2. Residential PCC driveway and parking areas not within the public or private
street right-of-way supported on medium to high expansive subgrade soils,
should be a minimum of 514 inches in thickness, reinforced with #3 reinforcing
bars at 18 inches on centers each way placed 2 inches below the top of slab.
Subgrade soils beneath the PCC parking and driveway should be compacted
to a minimum of 90% of the corresponding maximum dry density within the
upper 6 inches. Use a minimum 560-C-3250 concrete per Standard
Specifications for Public Works Construction (Green Book) standards.
3
3 VINJE &,MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
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PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 13
GIBRALTER STREET, JEREZ COURT. LA COSTA JULY 7, 2004
In order to enhance performance of PCC pavements supported on expansive
subgrade soils, a minimum 8 inches wide by 12 inches deep thickened edge
reinforced with a minimum of 1-#4 continuous bar placed near the botiiom
should be considered along the outside edges.
Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on
center (not to exceed 15-feet maximum) each way. Tool or cut as soon as the
slab will support weight and can be operated without disturbing the final finish
which is normally within 2 hours after final tinish at each control joint location
or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but
should not exceed 11^-inches deep maximi:im. In case of softcut joints, anti-
ravel skid plates should be used and replaced with each blade to avoid spalling
and raveling. Avoid wheeled equipments across cuts for at least 24-hours.
3. Subgrade and basegrade soils should be tested for proper moisture and
specified compaction levels and approved by the project geotechnical
consultant just prior to the placement of the base or asphalt/PCC finish surface.
4. Base section and subgrade preparations per structural section design will be
required for all surfaces subject to traffic including roadways, travelways, drive
lanes, driveway approaches and ribbon (cross) gutters. Driveway approaches
within the public right-of-way should have 12 inches subgrade compacted to a
minimum of 95% compaction levels and provided with a 95% compacted Class
2 base section per the structural section design.
In the case of expansive subgrade soils, provide 6 inches of Class 2 base
under curb and gutters and 4 inches of Class 2 base (or 6 inches of Class 111)
under sidewalks. Base layer under curb and gutters should be compacted to
a minimum of 95%, while subgrade soils under curb and gutters, and base and
subgrade under sidewalks should be compacted to a minimum of 90%
compaction levels.
F. General Recommendations
1. The minimum foundation design and steel reinforcement provided herein are
based on soil characteristics and are not intended to be in lieu of reinforcement
necessary for structural considerations. All recommendations should be further
evaluated based on final as-graded geotechnical conditions and confirmed by
the project architect/structural engineer.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 14
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
2. Adequate staking and grading control is a critical factor in properiy completing
the recommended remedial and site grading operations. Grading control and
staking should be provided by the project grading contractor, or surveyor/civil
engineer, and is beyond the geotechnical engineering services. Inadequate
staking and/or lack of grading control may result in unnecessary additional
grading which will increase construction costs.
3. Footings located on or adjacent to the top of slopes should be extended to a
sufficient depth to provide a minimum horizontal distance of 10 feet or one-third
of the slope height, whichever is greater (need not exceed 40- feet maximum)
between the bottom outside edge of the footing and face of slope. This
requirement applies to all improvements, and structures including fences, posts,
pools, spas, etc. Concrete and AC improvements should be provided with a
thickened edge to satisfy this requirement.
4. Expansive clayey soils should not be used for backfilling of any retaining
structure. All retaining walls should be provided with a 1:1 wedge of granular,
compacted backfill measured from the base ofthe wall footing to the finished
surface,
5. All underground utility and plumbing trenches should be mechanically
compacted to a minimum of 90% of the maximum dry density of the soil unless
otherwise specified. Care should be taken not to crush the utilities or pipes
during the compaction ofthe soil. Non-expansive, granular backfill soils should
be used.
6. On-site soils are potentially expansive moisture sensitive clayey deposits which
will undergo continued swelling and shrinkage upon wetting and drying.
Maintaining a uniform as-graded soil moisture during the post construction
periods is essential in the future perfomnance of site structures and
improvements. In no case should water be allowed to pond or accumulate
adjacent to the improvements and structures.
7. Site drainage over the finished pad surfaces should fiow away from structures
onto the street in a positive manner. Care should be taken during the
construction, improvements, and fine grading phases not to disrupt the
designed drainage patterns. Roof lines ofthe buildings should be provided with
roof gutters. Roof water should be collected and directed away from the
buildings and structures to a suitable location. Consideration should be given
to adequately damp-proof/waterproof the basement walls/foundations and
provide the planter areas adjacent to the foundations with an impermeable liner
and a subdrainage system.
2 VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
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PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 15
GIBRALTER STREET, JEREZ COURT, LA COSTA JULY 7, 2004
8. Based upon the result of the tested soil sample, the amount of water soluble
sulfate (S04) was found to be 0.021 percent by weight which is considered
negligible according to the California Building Code Table No. 19-A-4. Portland
cement Type I or II may be used.
9. Final plans should retiect preliminary recommendafions given in this report.
Final foundafions and grading plans should also be reviewed by the project
geotechnical consultant for conformance with the requirements of the
geotechnical investigation report outlined herein. More specific
recommendations may be necessary and should be given when final grading
and architectural/structural drawings are available.
10. All foundation trenches should be inspected to ensure adequate footing
embedment and confirm competent bearing soils. Foundation and slab
reinforcements should also be inspected and approved by the project
geotechnical consultant.
11. The amount of shrinkage and related cracks that occur in the concrete slab-on-
grades, flatworks and driveways depend on many factors, the most important
of which is the amount of water in the concrete mix. The purpose of the slab
reinforcement is to keep normal concrete shrinkage cracks closed tightly. The
amount of concrete shrinkage can be minimized by reducing the amount of
water in the mix. To keep shrinkage to a minimum the following should be
considered:
* Use the stiffest mix that can be handled and consolidated satisfactorily.
* Use the largest maximum size of aggregate that is practical. For example,
concrete made with %-inch maximum size aggregate usually requires about
40 Ibs more (nearly 5-gal.) water per cubic yard than concrete with 1-inch
aggregate,
* Cure the concrete as long as pracfical.
The amount of slab reinforcement provided for conventional slab-on-grade
construction considers that good quality concrete materials, proportioning,
craftsmanship, and control tests where appropriate and applicable are provided.
12. A preconstrucfion meeting between representatives of this office, the property
owner or planner, city inspector and the grading contractor/builder is
recommended in order to discuss grading/construction details associated with
the site development.
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT PAGE 16
GIBRALTER STREET, JEREZ COURT. LA COSTA JULY 7, 2004
VIII. LIMITATIONS
The conclusions and recommendations provided herein have been based on all available
data obtained from site observations, research and review of pertinent geotechnical reports
and plans, subsurface exploratory excavations, as well as our experience with the soils and
foi^mational materials located in the general area. The materials encountered on the
project site and utilized in laboratory tesfing are believed representative of the total area;
however, earth materials may vary in characteristics between excavations.
Of necessity we must assume a certain degree of continuity between exploratory
excavations and/or natural exposures. It is necessary, therefore, that all observafions,
conclusions, and recommendafions be verified during the grading operation. In the event
discrepancies are noted, we should be contacted immediately so that an inspection can
be made and additional recommendations issued if required.
The recommendations made in this report are applicable to the site at the fime this report
was prepared. It is the responsibility of the owner/developer to ensure that these
recommendations are carried out in the field. It is almost impossible to predict with
certainty the future performance of a property. The future behavior of the site is also
dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site
drainage patterns.
The firm of VINJE & MIDDLETON ENGINEERING. INC.. shall not be held responsible for
changes to the physical conditions of the property such as addition of fill soils, added cut
slopes, or changing drainage patterns which occur without our inspection or control.
The property owner(s) should be aware of the development of cracks in all concrete
surfaces such as floor slabs and exterior stucco associated with normal concrete shrinkage
during the curing process. These features depend chiefly upon the condition of concrete
and weather conditions at the time of construction and do not reflect detrimental ground
movement. Hairiine stucco cracks will often develop at window/door corners, and floor
surface cracks up to Vs-inch wide in 20 feet may develop as a result of normal concrete
shrinkage (according to the American Concrete lnstitute).This report should be considered
valid for a period of one year and is subject to review by our firm foiiowing that fime. If
significant modificafions are made to your tentative development plan, especially with
respect to the height and location of cut and fill slopes, this report must be presented to us
for review and possible revision.
Vinje & Middleton Engineering, Inc., warrants that this report has been prepared within the
limits prescribed by our client with the usual thoroughness and competence of the
engineering profession. No other warranty or representation, either expressed or implied,
is included or intended.
VINJE 8d MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
PRELIMINARY GEOTECHNICAL UPDATE REPORT
GIBRALTER STREET. JEREZ COURT, LA COSTA
PAGE 17
JULY 7, 2004
3
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3
Once again, should any questions arise concerning this report, please do not hesitate to
contact this office. Reference to our Job #04-287-P will help to expedite our response to
your inquiries.
We appreciate this opportunity to be of sen/ice to you.
VINJE & MIDDLETON ENGINEERING, INC.
Dennis Middleton
CEG #980
Steven J. Melzer
RG #6953
DM/SMSS/SJM/jt
Distribufion: Addressee (5)
c:/jl/myfiles/updates.04/04-287-P
4
VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214
Ghmrj Vi
2002 DQLorma. Topo USA ®- Dain copyrfoht of content owner,
www.dslarme.com
RETAINING WALL DRAIN DETAIL
Typical - no scale
droinoge
Waterproofing
Perforated droin pipe
• Granulor, non-expansive ^
backfill. Compocted.;'/
Filter Moferiol. Crushed rock (wropped in
filter fabric) or Closs 2 Permeable Moferjal
(see specifications below)
Competent, approved
soils or bedrock
I t'l I I III II II I it**r**i I
cij^ltjF-iEpiilMlliMlitl!! PMf lll|ir>AL
y.te mHisWHtei
s|ai,ftiil|?|U.^, -t" R*|l!iJii.i:il
. W\\n
M ' . , ' ' •ijfr'iil'u
•p.!,* •, • . •• rfH-tS
ffii.F ; lllr-•!li^
hM.IH* ' "fl f?
hfftirl;" " • D,.?
Hfi; S» •' • • P,':t
CONSTRUCTION SPECIFICATIONS:
1. Provide granular, non-expansive backfill soil In 1:1 gradient Vk^edge betiind wall. Compact backfill to minimum 90% of laboratory
standard.
2. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of wail or back
drain system as outlined beiow.
3. Backdrain should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) wilh perforations down. Drain to suitable outlet ^
at minimum 1 %. Provide V* - VA' cmshed gravel filter wrapped In filter fabric (Mlraft 140N or equivalent), Delete fiiter fabric
wrap If Caltrans Class 2 permeable material Is used. Compact Class 2 material to minimum 90% of laboratory standard.
4. Seal back of wall wilh waterproofing in accordance with architect's specifications.
5. Provide positive drainage to disallow ponding of water above wall. Lined drainage ditch to
minimum 2% flow away from wall is recommended.
' Use 1 Vi cubic fool per fool wrilh granular backflll soil and 4 cubic foot per foot if expansive backfill soli is used.
VINJE & MIDDLETON ENGINEERING, INC.
PLATE 3
ISOLATION JOINTS AND RE-gNTRANT CORNER REINFORCEMENT
Typical - no scale
RE-ENTRANT CORNER—*
REINFORCEMENT
NO.4 BARS PLACED l.s"
BELOW TOP OF SLAB
RE-ENTRANT
CORNER CRACK
NOTES:
1. Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b).
If no isolation joints are used around columns, or If the corners of the isolation joints do not meet the contraction
joints, radial cracking as shown in (c)may occur (reference ACI).
2. In order to control cracking at the re-entrant corners (±270° corners), provide reinforcemeni as shown in (c).
3. Re-entrant corner reinforcement shown herein is provided as a general guideline only and is subject to verification
and changes by the project architect and/or structural engineer based upon slab geometry, location, and other
engineering and construction factors.
VINJE & MIDDLETON ENGINEERING, INC.
PLATE 4
APPENDIX A
i
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3
70
60-i
STREET
Fill (af)-
Terrace Deposit (Qt).
— Formational Rock (Td)
GEOLOGIC
CROSS-SECTIONS
B
90-1
80-
Terrabe^
-120
-100
f FilT?(al
.L I
Formational Rock (Td)
-80
80-
J^Filh(af]^,-
-100
Terr ace
Formational Rock (Td)
A'
120
-80
Scale 1=20
PLATE 2
MV ENGINEERING, INC.
2450 Vineyard Ave., Suite 102
Escondido, CA 92029-1229
619/743-1214 Fax:739-0343
s
Job #1017-91
February 20, 1991
Mr. Hossein Zomorrodi
Zomorrodi Engineering
5983 cirrus Street
San Diego, California 92110
Preliminary Soil and Geotechnical investigation.
Graded Hillside Property, Gibraltar street Near
Jerez Court, La costa Area of carlsbad, San Diego
county. California __
Pursuant to your request, MV Engineering, Inc. has completed the
attached investigation of soils and geotechnical conditions at the
subject site.
The following report summarizes the results of our field
investigation, laboratory analyses, and conclusions, and provides
recommendations for the site development as understood. From a
geotechnical engineering standpoint, it is our opinion thai; the
site is suitable for the proposed development provided the
recommendations presented in this report are incorporated into the
design and construction of the project.
Thank you for choosing MV Engineering, Inc. If you have any
questions concerning this report, please do not hesitate to call
us. Reference to our Job #1017-91 will expedite our response to
your inquiries.
We appreciate this opportunity to^e of service to you.
MV ENGINEERING, INC.
Ralph M. Vxn-jB
GE #853
RMV/kmh
No. 863
Exp. 12-31-93
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
II. SITE DESCRIPTION/BACKGROUND 1
III. PROPOSED DEVELOPMENT 1
IV. SITE INVESTIGATION 2
V. GEOTECHNICAL CONDITIONS 2
A. Earth Materials 2
1. Fill (af) 2
2. Terrace Deposit (Qt) 2
3. Bedrock (Td) 2
B. Laboratory Testing/Results ..... 3
1. Maximum Dry Density and
Optimum Moisture Content 3
2. In-Place Dry Density and
Moisture Content 3
3. Expansion Index Test 4
4. Direct Shear Test 4
C. Geologic Structure 4
2 D. Seismicity ^
E. Slope Stability 5
VI. CONCLUSIONS/RECOMMENDATIONS 5
1^ A. Grading. . ^
^ B. Foundations 6
^ C. Interior Slabs 7
m D. Exterior Slabs 8
IP E. Retaining Walls 8
^ F. Design ^
" G. Drainage/Erosion Control 9
d H. Pavement 10
^ I. Utility Trench Backfill 10
2 J. Plan Review 10
^ K. Geotechnical and Construction
Inspections 10
_ L. Preconstruction Conference 11
2 VII. LIMITATIONS H
(continued)
3
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S
Table of Contents/Page 2
APPENDIXES
APPENDIX "A" - SUBSURFACE INVESTIGATION
Plate
Geotechnical Map 1
Geologic Cross Sections 2
Test Pit Logs (including Key). . . .3-7
Isolation Joints and Re-Entrant
Corner Reinforcement 8
Typical Wall Drainage Detail .... 9
APPENDIX "B" - SPECIFICATIONS FOR CONSTRUCTION OF CONTROLLED
FILLS, AND UNIFIED SOIL CLASSIFICATION
3
3
PRELIMINARY SOIL AND
GEOTECHNICAL INVESTIGATION
GRADED HILLSIDE PROJECT
GIBRALTAR STRBBT NEAR JEREZ COURT
LA COSTA AREA OP CARLSBAD
SAN DIEGO COUNTY, CALIPORNIA
I. INTRODUCTION
The study property consists of three vacant graded sites along the
north side of Gibraltar Street in La Costa. The site location is
depicted on the Vicinity Map included on the Geotechnical Map
attached with this transmittal as Plate 1.
We understand that the property is presently planned to support
several attached dwelling units in separate buildings as shown on
Plate 1. The purpose of this study was to determine geotechnical
conditions in the planned construction areas and their influence
on the planned improvements.
II. SITE DESCRIPTION/BACKGROUND
The study site is located within graded hillside terrain north of
and below La Costa Avenue. Access onto the property is provided
by Gibraltar Street which defines the north property boundary. The
site consists of three level pad surfaces which are surrounded by
graded slopes. Rear areas are terminated by a large cut slope
which ascends as much as 7 0 feet onto off site terrain above.
Smaller side and front slopes define each of the three pads as
shown on Plate 1. Slope gradients are 1^:1 (horizontal to
vertical).
Surface areas are bare or support a light cover of native grass.
Site drainage sheetflows over surface areas toward Gibraltar
Street. Some erosion of front slopes has occurred as a result of
concentrated run-off.
Technical records for the grading are unavailable. Aerial photo-
graphs and topographic maps of the area indicate that site grading
took place between 1960 and 1977.
III. PROPOSED DEVELOPMENT
3
3
3
2
Detailed development plans for the project are presently
^ unavailable. However, we understand that the site is planned to
^ support attached dwelling units as shown on Plate 1. Construction
^ will be conventional wood-frame and stucco supported by continuous
foundations. Slab-on-grade floors are planned for lower units.
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION
GIBRALTAR STREET. LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991
Planned grades (shown on Plate 1) indicate modest cut/fill grading
to establish new, level building surfaces. A maximum cut of
12 feet and a maximum fill of seven feet is planned. Retaining
walls are proposed throughout as shown.
IV. SITE INVESTIGATION
Geotechnical conditions at the site were determined chiefly by
field mapping of available surface exposures and the excavation of
seven exploratory trenches dug with a tractor-mounted backhoe. The
trenches were logged by our project geologist who retained
representative soil/rock samples for laboratory testing. Results
of the testing are tabulated in a following section. Geologic
cross sections and logs of the test trenches are attached as
Plates 2 through 7 (including the Key).
V. GEOTECHNICAL CONDITIONS
A. Earth Materials - The following earth materials were encountered
at the project and will affect site development:
1 Fill (af) - Fill soils occur at the project, particularly
beneath front areas of the graded parcels. The fill consists
chiefly of locally derived sands and silts with included rock
fragments. The fill generally occurs in a loose condition.
w 2. Terrace Deposit (Qt) - Natural Terrace Deposit soils underlie
^ the front portion of the project. These are dark colored
^ clay-silt deposits which mantled lower hillside terrain along
• the southern margin of San Marcos Creek. Deposits at the
site occur in a soft to stiff condition. 3 3. Bedrock (Td) - Formational sedimentary rocks underlie rear
3 areas of the property including the large ascending slope.
The rocks consist of interbedded sandstone and siltstone
units which are widely exposed in local hillside terrain to
• the south. On-site exposures occur in a firm to locally hard
fl condition.
4 Details of the earth materials underlying the pro:) ect are
included on the enclosed logs (Plates 4 through 7). ^ The
approximate distribution of major earth materials is depicted
on Plate 1 and on the Geologic Cross Sections enclosed as
Plate 2.
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 3
GIBRALTAR STREET. LA COSTA AREA QF CARLSBAD FEBRUARY 20, 1991
B. Laboratory Testlna/Results - Excavations of on-site earth
deposits will result in soils which have been grouped into the
following soil types:
SOIL TYPES
Soil/Rock Type
1
2
3
4
soil Description
light brown clayey sand/
sandy clay
light colored silty sand
tan to brown silty sand
dark brown silty to sandy
clay
m m
i
a
The following tests were conducted in support of this study:
1, Maximum Dry Density and Optimum Moisture Content - The
maximum dry density and optimum moisture content of selected
soil types were determined in accordance with ASTM D-1557-
78. The results are tabulated below.
Test
Location
soil
Type
TP 1@5' 2
TP 2@2' 4
TP = Test Pit
Maximum Dry
Density (pcf)
115.7
114.5
Optimiua
Moisture
Content f%)
15.3
15.6
be used during the grading where These results may
applicable.
In-Place Dry Density and Moisture content - In-place dry
densities and moisture content of representative chunk soil
samples were determined using the water displacement method.
Results are presented below.
Test
Location
Soil
Type
Dry Density
focf)
Field Moisture
f%)
TP 1@5' 2 133.8 7.2
TP 1@8« 2 101.1 17.3
TP 1@8' 2 108.4 17.0
TP 1@10' 3 129.8 12.0
TP 1@13' 3 110.1 17.0
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 4
GIBRALTAR STREET. LA COSTA AREA OF CARLSBAD FEBRUARY 20. 1991
3. Expansion Index Test - The potential for on-site soils to
change in volume in response to moisture fluctuations was
determined by expansion index tests. The tests were
performed in accordance with the Uniform Building Code
Standard Procedure 29-2. Results are presented below.
Remolded Saturated
Sample Moisture Moisture Expansion
Location Content (%) content (%) Index
TP 1@8' 19.3 29.3 46
TP 2@2' 12.8 33.6 98
4. Direct Shear Test - A direct shear test was performed on a
representative site soil sample for strength parameters in
the lateral load and bearing capacity calculations. Three
soil specimens were prepared by molding them in 2h-inch
diameter, 1-inch high rings to 90% of the corresponding
maximum dry density and optimum moisture content and soaked
overnight. The specimens were loaded with normal loads of
1, 2, and 4 KSF respectively and sheared to failure in an
undrained shear. The results are presented below.
wet Angle of Apparent
Soil Density Int. Frio. cohesion
Location Tvoe fpcf> <f> fdegree) c. (psf)
TP 1@5» 2 119.0 34 146
C. Geologic Structure - Bedding conditions within on-site bedrock
are poorly developed. However, noted exposures indicate nearly
flat-lying conditions throughout.
Faults or significant shear zones are not in evidence at the
project site.
D. Seismicity - As with most areas of California, the San Diego
region lies within a seismically active zone. However, coastal
areas of the county are characterized by low levels of seismic
activity relative to inland areas to the east. During a 40-year
T period (1934-1974), 37 earthquakes were recorded in San Diego
w coastal areas by the California Institute of Technology. None
d of the recorded events exceeded a Richter magnitude of 3.7 nor
^ did any of the earthquakes generate more than modest ground
2 shaking or significant damages. Most of the recorded events
• occurred along various offshore faults which characteristically
^ generate modest earthquakes.
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION
^?n"gTAR STRE^i^. T.A COSTA AREA QF CARLSBAD FEBRUARY 20, 1991
Historically, the most significant earthquake events which
affect local areas originate along well known, distant fault
zones to the east. Less significant events have been recorded
along off shore faults to the west. The following list
represents the most significant active fault which typically
impact the region.
Fault zone Distant from Site
Elsinore Fault 28 miles
San Jacinto Fault 57 miles
San Andreas Fault 82 miles
Coronado Bank Fault 20 miles
More recently, the number of seismic events which affect the region
appears to have heightened somewhat. Nearly 40 earthquakes of
magnitude 3.5 or higher have been recorded m coastal regions
between January, 1984 and August, 1986. Most of the earthquakes
are thought to have been generated along offshore faults. For the
most part, the recorded events remain moderate shocks which
typically resulted in low levels of ground shaking to local areas.
A notable exception to this pattern was recorded on July 13, 1986.
An earthquake of magnitude 5.3 shook North Coast coastal areas
resulting in $400,000 in damages and injuries to 30 people. The
quake occurred along an offshore fault located nearly 30 miles
southwest of Oceanside. The event resulted in moderate to locally
high levels of ground shaking in areas of the study site. The
increase in earthquake frequency in the region remains a subDect
of speculation among geologists. However, the 1986 event is
thought to represent the highest levels of ground shaking which can
be expected at the study site as a result of seismic activity.
Ground separation during expected earthquake events is not antici-
pated at the study site.
E. Biopa Stability - Existing site slopes do not evidence geologic
instability. Underlying bedrock units are flat-lying, sedi-
mentary rocks which are expected to Perform w^ell in modest
slopes planned for redevelopment. The stability of off-site
slopes is beyond the scope of this transmittal.
VI. CONCLUSIONS/RECOMMENDATIONS
Based upon the foregoing investigation, development of the study
property for residential purposes is feasible from a geotechnical
viewpoint. The property is underlain by old fill and Terrace
Deposit soils which, in their present condition, have a potential
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION ^^^??«f
^^BSAS^AR STREP^- T.A CQSTA APl^A QF CARLSBAD FEBRUARY 20, 1991
for detrimental soil movement. Loose, compressible soils, as well
as expansive soils, are present at the site. Consequently,
?Lrad^ing of near-surface soils is recommended in order to create
safe and stable building surfaces. Recommendations given below are
consilient with site geotechnical conditions and should be incor-
porated into finalized plans.
A. Grading:
1. Grading operations at the property should generally be
conducted in accordance with the enclosed "Specifications for
construction of Controlled Fills" attached with this report
as Appendix "B".
2. Prior to grading, site vegetation and other deleterious
debris should be removed from the property.
3. Near surface soils should be excavated to grade elevations
depicted on Plate 1. The indicated removal depths apply to
the existing plans and the finished elevations given on
P?ate 1 Changes in the plans will likely^ require
modifications in the removal elevations given herein.
4. After completion of the indicated removals, planned grades
should be achieved by on-site soils as properly compacted
fill The fill should be brought to optimum moisture levels
and mechanically compacted in thin, horizontal lifts to a
minimum 90% of the laboratory maximum density value.
5. on-site soils may be re-used in compacted fill. However,
dark colored Terrace Deposit soils represent the most expan-
sive deposits at the site. Consideration should be given to
placing these deposits within the deeper fills as a means of
minimizing the expansive potential of finish grade soils.
B. Foundations - At the completion of rough grading, this office
should confirm by testing the actual e^P;i^^^°J^,P°^/"^^^^^^^
finish grade soils so that more specific foundation/slab
recommendations can be provided. However, based upon site soil
characteristics, it is assumed that expansive soils will be
exposed at fini'sh grade. Consequently, the following founda-
tion/slab recommendations are provided for preliminary design
and estimating purposes.
1. Foundations should be founded a minimum depth of 24 inches
below the lowest adjacent grade (not including sand/gravel
under the slab). Footings should maintain a minimum width
of 12 inches. Isolated square footings are not recommended.
inches above the bottom of the footing.
3 Dowel the slab to the footings using #4 reinforcing bars
spaced 18 inches on center extending 20 inches into the
?oo?ing and slab. The dowels should be Pl/^^<l,f J-^^^f^^
in the slab. Alternate the dowels each way for all interior
footings.
4. After the footings are dug and cleaned, place the reinforcing
steel and dowels and pour the footings.
5. This office must be notified to inspect the footings and
reinforcing prior to pouring concrete.
C. Interior Slabs:
1 All utility trenches under slabs in expansive soils should
be backfilled with sand (S.E. 30 or greater) and flooded with
water to achieve compaction.
2. onoo the concrete for the footings has cured a„d undergroun^
„-nn+-i*P«i tested, place four inches of pea gravei ^^ inuii
?oci) over ?he slab subgrade. Flood with "ater to the top
o? the pea gravel, and allow the slab subgrade to soak for
approximately seven to 10 days.
moisture testing.
NOTE. If sufficient moisture is present, flooding will not
be requirel!^ The dowels may be deleted, and the footings and
slab may be poured monolithically.
3. When the required moisture content It^l^^^l
a 10-mil plastic moisture barrier over the V8-inch rocK ana
place two^ inches of clean sand (SE 30 or greater) on top of
the plastic.
A TTce «3 reinforcing rods spaced 18 inches on center each way
placed one"and onl-half inches below the top of the ^lab.
All Slabs should be a minimum of five inches in thickness.
PRELIMINARY SOIL AND GEOTECHNICAL I^^ESTI^^^^ FEBRUARY2of?Li flIBRALTAR fTWEET. LA pOSTA AREA OF CARLSBAD FEBRUARY 20, 19 9 4
5. This office must be notified to inspect the sand, slab
thickness, and reinforcing prior to concrete pour.
6. provide contraction joints consisting of ^^^^^^^^ ^P^^,!^.?;!
feet on center each way within 72 hours of concrete Pour for
a?rinterior slabs. -Bhe sawcuts must be a minimum of one-
half inch in depth and must not exceed three-quarter inch in
depth or the reinforcing may be damaged.
1^^^»r^or Slabs (patios, walkways, and driyeways) "/l^^^^^^^i^^
slabs (walkways, patios, etc.) must be a minimum of four incnes
?i'thickness Reinforced with 6x6/10x10 welded wire -esh placed
one and one-half inches below the top of the slab. Driveways
mSst be a minimum of five inches in thickness and reinforced
wl?h #3 ?e?nforcrng bars spaced 18 inches on center each way
placed one and one-half inches below the top of the ^lab. Use
six inches of clean sand (SE 30 or greater) beneath all slabs.
?JSviSe contraction joints consisting of sawcuts spaced six feet
on center each way within 72 hours ^ P^'J^l s\\l,^Sln-of the sawcuts should be as described in interior slab rein
forcing, item (6) above.
special attention should be given to any "re-entrant" corners
and curing practices (during and after concrete pour) to limit
c^ackSg? Construction recommendations are given on the
enclosed Plate 8.
The concrete reinforcement recommendations provided herein
should nof be considered to preclude the development of
iTinUl related cracks, etc.; rather these recommendat^^^^
are intended to minimize this potential. 1^.shrinkage cracxs
do develop, as is expected from concrete, reinforcements tend
to limit the propagation of these features. These recommenda-
tLirire beUeved^ to be reasonable and in keeping with the
local standards of construction practice.
Footing and slab designs provided herein are based upon soil
cSarac?eristics only a^nd sLuld not supersede more restrictive
requirements set forth by the architect or the structural
engineer. Please note that minimum requirements set forth by
?Ilr Respective government agencies may also supersede the
recommendations provided in this report.
E. Retaining Walls
1 Expansive clayey soils should not be used for backfilling of
aS retaining structure. All retaining walls, including
those planned to surround the interior gymnasium, should be
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION PAGE 9
GIBRALTAR STREET. LA COSTA AREA OF CARLSBAD FEBRUARY 20, 1991
provided with a 1:1 v/edge of granular, compacted backfill
measured from the base of the wall footing upward to the
finished surface. Retaining walls should be provided with
a backdrainage as outlined on the enclosed Plate 9.
2. Lateral active pressures for sandy soils with a minimum
friction angle of 3 0 degrees and assumed drained backfill
conditions are provided below. These values may be used for
preliminary design estimates only and are to be re-evaluated
when the characteristics qf the backfill soils have been
determined. Revised recommendations should be anticipated.
Passive resistance is also provided.
Active Pressure = 53 pcf equivalent fluid pressure, canti-
lever, unrestrained walls with 2:1 backfill surface.
Active Pressure = 34 pcf equivalent fluid pressure, canti-
lever, unrestrained walls with level backfill surface.
At Rest Pressure = 53 pcf equivalent fluid pressure, re-
strained walls.
•Passive Pressure = 421 pcf equivalent fluid pressure, level
surface condition.
*Note: Because large movements must take place before
maximum passive resistance can be developed, the earth
pressures given for passive conditions should be reduced by
a safety factor of two.
3. A coefficient of friction of 0.35 may be considered for
concrete on soils. This value is to be verified at the
completion of grading when the properties of the subgrade
soils are specifically known.
P. Design - Based upon the nature of on-site soils and the
foregoing recommendations, an allowable bearing value of
1900 pounds per square foot for a 12-inch wide by 24-inch deep
footing may be utilized for design purposes. This value applies
to dead plus live loads and may be increased by one-third for
wind and seismic loading.
G. Drainage/Erosion Control
1, Excessive moisture can adversely impact the stability of
hillside properties. Consequently, finished grades should
provide positive drainage away from structures and site
slopes. Ponding of surface waters should not be allowed at
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION or^igi?
flTBRALTAR STREET. LA CQSTA AREA OF CARLSBAD FEBRUARY 20, 1991
the site. Construction soils should be dispersed in a Proper
manner that will not interfere with positive drainage flow.
2. consideration should be given to providing a suitable plant
growth upon the graded cut slopes around the north perimeter
of the property as a means of controlling surface erosion.
Plants should be broad-leafed, deep-rooted types which
require minimum irrigation as recommended by the project
landscaper.
overwatering of on-site vegetation should i>®. ^^^if^J- ^"i^
the amount of irrigation necessary to sustain plant growth
should be provided.
3. Back-drainage should be provided behind all retaining walls
at the project in accordance with the attached Plate 9.
H. Pavement - AC pavement surfaces should only be placed atop
grLular, non-expansive subgrade soils which have been compact^^
to 95% of the laboratory standard in the upper 12 inches,
specific pavement designs can best be provided at the completion
of rough grading based upon R-value tests of the actual soils.
Howeve?, for preliminary design purposes, a section of two-inch
AC over five inches of compacted Class II base "jay be utilized
for preliminary design purposes. Post grading tests should be
conducted to verify this design.
I. utility Trench Backfill - All underground utility trenches
should be compacted to a minimum of 90% of the maximum dry
density of the'^oil unless otherwise specified ^/J^e respective
agencies. Care should be taken not to crush the utilities or
pipes during the compaction of the soil. Non-expansive,
granular backfill soils should be used.
J. Plan Review - Final grading and foundation plans should incor-
gorate recommendations provided , in this transmittal a^^^^^^
Reviewed and approved by this office. If the final development
plans significantly change, or if they were not available at the
time of this investigation, further investigation and subsoil
study may be required and should be anticipated.
K. geotechnical Construction Inspections - ^fading operations
should be continuously inspected by the project geotechnical
consultant. Testing of fill will assist the contractor to
achieve proper moisture and compaction levels. f^jticular
attention should be given to removal operations and drainage
installation.
consultant.
^. rr—rr—^"" .inference - A Trty'"own'^^^ representatives of t^is^offxce and the ProP/^^^ ^1^,, ^ i3
lli:Zl^.sr Ar^o Ti.J!;%rt.in,/.or,s..natior, details
associated with site development.
VII. T.TyJITATIONS
The conclusions and reco^nendations provided herein^^^^^^^^^
on all available data obtained fit^ the%oLls and
laboratory analyses, as "ejl/f ""^/^P^erafarea! The materials
^-^Kr^a^l^s^ryna^rTfn^cf^^^^^^^^^^^ ~ excavations.
Of necessity „e must ^/-^„\^:,*;,%%V°ls?°f^^
exploratory excavations a"'*/?^ an recoraiendations
«ec\1ln^ III -^':V.:iT^\^^^^'r:^^^ i^^sued if
required.
The recommendations made in this report are applicable to^t^^^^^^
?L*^^n\^?;d^5ilore?°"^t\"Tni:rTt^at fhe^sr-Jeoomm^endations are
carried out in the field.
•1,1^ «r-t.Hic!t with certainty the future It is almost l™P°|"^le to predict with ^ j ^ .^^
^I^fn™n™m\?o"ru"JredI=?able variables, such as earthguakes,
rainfall, and on-site drainage patterns.
The firm of MV ENGipERING INC shall not be heW
iTfm ^oiiro?rhtrglnrd™e patt^^mTw^hich^ occur subsequent
to issuance of this report.
'"^'z ."^sriecrt^o^ r^ivferr out /oTioiirg-^^hV^tir. 'r.
s?^n^lican't'rodiricaUon%" ar\ made to .tentatWe dev lo^^^^^^
^ir'fitrsfofe^s^ "ti>fs rfp^rf m^st^^e fr^fented to us for review
and possible revision.
d
a
3
PRELIMINARY SOIL AND GEOTECHNICAL INVESTIGATION zV'^lgll ^?g""^grSTRE^-^, T.T. PQf^TA AREA OF CARLSBAD FEBRUARY gO, 1991
included or intended.
°?IL;^o-not-hT^^afe^tno^^aS^
Job #1017-91 will expedite response to your inquiries,
we appreciate this opportunity to ..be of service to you.
MV ENGINEERING, INC.
Ralph M. Vinje
GE #863
AL. //nu.
DeYinis Middleton
CEG #980
RMV/DM/kmh
a:1017-91.pre
APPENDIX "A"
GEOLOGIC
CROSS-SECTIONS
-1—. Formational Rock (Td)
. _. -.X
-100
. Formational Rock (Td)
120
-80
Formational Rock (Td)
A'
120
100
-80
PLATE 2
PRIMARY DIVISIONS
eg S
8 1
o o
OJ
Q LU z < tn O
LU W CC
<
O QC o S
_ o
U. Z UJ
O Z N
U. < W
E
X a: Ci
^§
GRAVELS
MORE THAN HALF
OF COARSE
FRACTION IS
LARGER THAN
NO. 4 SIEVE
u. o
o
CO
o
UJ z
<
a lu
UJ QC Z O
E S
< r
z <
X
LU
tn N
UJ (/)
CO «
$2 S
_l CM < .
55
SANDS
MORE THAN HALF
OF COARSE
FRACTION IS
SMALLER THAN
NO. 4 SIEVE
CLEAN
GRAVELS
(LESS THAN
5% FINES)
GRAVEL
WITH
FINES
CLEAN
SANDS
(LESS THAN
5% FINES)
SANDS
WITH
FINES
SILTS AND CLAYS
LIQUID LIMIT IS
LESS THAN 50%
SILTS AND CLAYS
UQUID LIMIT IS
GREATER THAN 50%
HIGHLY ORGANIC SOILS
GROUP
SYMBOL
SECONDARY DIVISIUNS |
GW Well graded gravels, gravel-sand mixtures, lillie or no fines.
GP Poorly graded oravels or gravel-sand mixtures, little or no fines.
GM Silty gravels, gravel-sand-sill mixtures, non-plaslio fines.
GC niavfiv aravels, gravel-sand-clay mixtures, plaslic fines.
SW Well graded sands, gravelly sands, little or no fines.
SP Poorly graded sands or gravelly sands, little or no fines.
• SM Siltv sands, sand-sill mixtures, non-plastic fines.
SC Clavev sands, sand-clay mixtures, plastic fines.
ML
inofoanic slits and very fine sands, rock Hour, silly or ciayey fine 1
'""Tands br clajey silts with slight plasticity.
CL Inorganic clays of lov/ to medium plasticity, gravelly clays, sandy 1
clays, silly clays, lean clays. _ —
OL Organic silts and organic silly clays ol low/ plasliclly.
MH
Inorganic silts, micaceous or diatomaceous fine sandy or silly
soils, elastic silts. . •
CH Inorganic clays of high plasticity, fat clays.
OH Organic clays of medium lo high plasticity, organic sills.
PT Peal and other highly organic soils.
GRAIN'SIZES U.S. STANDARD SERIES SIEVE
200 40 10
CLEAR SQUARE SIEVE OPENINGS
3/4" 3" 12"
SILTS AND CLAYS
SAND
FINE MEDIUM COARSE
GRAVEL
FINE COARSE
COBBLES BOULDERS
RELATIVE DENSITY
CONSISTENCY
SANDS, GRAVELS AND
NON-PLASTIC SILTS
BLOWS/FOOT
VERY LOOSE 0 • 4
LOOSE 4 - 10
MEDIUM DENSE 10 • 30
DENSE 30-50
VERY DENSE OVER 50
CLAYS AND
PLASTIC SILTS
STRENGTH BLOWS/FOOT
VERY SOFT 0 - % 0 • 2
SOFT V* - '/» 2 • 4
FIRM y. -1 4 - 8
STIFF 1 • 2 8 - ie
VERY STIFF 2 • 4 16 • 32
HARD OVER 4 OVER 32
1 Blow count 140 pound hammer falling 30 inches on 2 men u u. -
2. UnconS'compressive strength per SOILTEST pocket penetrometer CL-ZOO
/\ = undisturbed chunk sample
1 I = disturbed sample
= sanct cone test
I 24, = Standard Penetration Test (SPT) (ASTM 0-1586}
I with biow counts per 6 inches
California Sampler with blow counts per 6 inches
MV ENGINEERING. INC.
KEY TO EXPLORATORY BORING LOGS
MnmoH^nilClassifica^^^ System (ASTM D-2487)
ZOMORROBI ENGINEERING
GILBRALTAR STREET NEAR JEREZ COURT, LA_COSTA
PROJECT NO.
1017-91
PLATE KEY
TEST PIT 1
t
?
s
3
TOTAL DEPTH 14'
TEST PIT 2
FILL/TOPSOIL: dark brown clay,
niofst, stiff.
TOTAL DEPTH 5'
PLATE //A
TEST PIT 3
d
3
3
s
a
iBEDROCK (Td): siltstone/
pale brown, sanely,
tieht, massive. .
TOTAL DEPTH
TEST PIT 4
FILL (af): c»ayey slM
Ifght to dark brown,
Includes scattered
bedrock fragment*,
moist, loose.
TOPSOIL: dark brown clay,
moist, soft' to stiff
TERRACE DEPOSIT (Qt): brown silt, weathered, soft,
gradational contact above.
TOTAL DEPTH 6.5'
PLATE #5
TEST PIT 5
m
:
4
3
3
3
3
TOTAL DEPTH 5'
TEST PIT 6
FILL (af): light colored clayey silt, dry,
loose, mottled;
'FILL (af): brown sandy cU
moist, loose.
TOTAL DEPTH 8'
PLATE ite
TEST PIT 7
FILL (af): Hght colored clayey silt to sand,
dry, loose.
ACE DEPOSIT (Ot): broWn clay, soft to stiff^
TOTAL DEPTH 10'
BEDROCK (Td): sandstone, tan brown
damp lo moist, cemented
PLATE #7
T.qOLATION JOINTS AND RE-ENTRANT CORNER REINFORCEMENI
Typical - no scale.
isolacion
joints
contraction joints
re-entrant corner,
reinforcement
No. 4 bars placed
li" below top
of slab
contraction
joints
potential re-entrant
corner crack
(1) Isolation joints around the columns should be either circular as shovm
in lTor diamond shaped as shown in (b) . If no isolation ,oxn s are used
around columns, or If the corners of the isolation joints do not the
contraction joints, radial cracking as shown in (c) may occur (reference ACI).
(2) In order to control cracking at the re-entrant corners (±270° corners), provide
reinforcement as shown in (c).
(3) Re-entrant corner reinforcement shown herein is provided as a general guideline
onlv and is subiect to verification and changes by the project architect and/or
^truc'ral e^g^neer based upon slab geometry, location, and other engineering
and construction factors.
Plate //8
BACK DRABSi DETAIL
6' MIN
OVERLAP
3/4'-1-1/2'
CLEAN QRAVEL*
(31t?yit. MIN.)
4* 0
NON-PERFORATED
PIPEv^
FILTER FABRIC
ENVELOPE (MlflAFt
140N OR APPROVED
EQUIVALENT)*
SEE T-CONNECTlON
DETAIL
a' MIH.
COVER
4- fi
PERFORATED
4' MIN.
BEDDINQ
SUBDRAIN TRENCH DETAIL
PERFORATED
PIPE
NON-PERFORATED
OUTLET PIPE
10' MIN.
EACH SIDE
CAP
T-CONNECTION DETAIL
*I£ Caltrans Class II permeable
mateclal is used in place of
3/4"-!^' gravel, fabric filter
may be deleted.
**SUBDRAIN TYPE - Subdrain type
should be Acrylonitrlle Butadiene
Stryene (A.B.S.), Polyvinyl
Chloride (PVC) or approved equiva-
lent. Class 125, SDR 32.5 should
be used for maximum fill depths
of 35 feet. Class 200, SDR 21
should be used for maximum fill
depths of 100 feet.
SPECIFICATIONS FOR CALTRANS
CLASS II PERMEABLE MATERIAL
U.S. Standard
SiRve Size % Passing
1" 100
3/4" 90-100
3/8" 40-100
No. 4 25-40
No. 8 18-33
No. 30 5-15
No. 50 0-7
No. 200 0-3
Sand Equivalent 75
PLATE # 9
APPENDIX "B"
9
8/88
SPECIFICATIONS FOR
CONSTRUCTION OF CONTROLLED FILLS
flENERAL nESCRIPTION
Report performed by this firm.
ShoSld be done under the ^"P?f7.^^^°" °* i^^al e^^^^^^ should
provided herein are desired by the owner/developer.
3 The construction of controlled fills shall consist of ole^ring
aAd^rJmSvaf o^'existing structures and foundations, /^-paratxon^of
land to be filled all other wo ™k necessary
rrofpiSe^tLTr^^^^^^^^^^
lines, grades, and slopes as shown on the accepted plans.
nT.TlARING ANH PREPARATTHM OF AREAS TO BE FILLED
1 All fill control projects shall have a preliminary soil
of the governing agency and the nature ot rne jou} uy ^
geotechnical engineer prior to grading.
9 All timber trees, brush, vegetation, and other rubbish shall
debris.
-1 Anv soft swampy, or otherwise unsuitable areas shall be
cirJS^tedly'drllnTe'or removal of impressible materia^^^^^
to the depths indicated on the plans and as directed Dy
geotechnical engineer.
uniform compaction by the equipment to be used.
R Mo fill shall be placed until the prepared native ground has
b;en approvedbJ the %oteohnlcal engineer or his representative
on site.
%ofizitii''^o ^^\?Lti>°" !iiiizt^nrai"'bi';,=t?%\irrbr c^^t "i^;i
^5™ 'u°n"d\%^urbed:"^n\\°u^'ll ground. A -^-^-ZZVA°°:JI:LT117I1
«r,^ v^iario wiHth should be cut. The geotechnical engineer snaxi
de?em?n: thfwidth and frequency of all succeeding benches which
will^i^y with the soil conditions and the steepness of slope.
7. After the natural ground has been P^^PJ^f ^i^^^^JJ^f thaHoJ
to the proper moisture content and compacted to not less than 90«
of maximum density per ASTM D-1557-78.
8. Expansive soils may require special compaction specifications
as directed in the preliminary soil investigation by the
geotechnical engineer.
9 In order to reduce the potential for differential settlement for
structures Placed on a transition area of the lot, the cut portion
ShS?d ^rundercut a minimum depth of three feet below the proposed
pad grade or to a minimum depth of twelve inches below the bottom
ofthe footing, whichever is greater and ^^^P^^f^*;^^^^
fill. The undercut should extend a minimum horizontal distance ot
ten feet outside the building perimeter.
10 caution should be used during the grading and trench
exiavationS so that existing adjacent or underground
;??u^?ures/imp?ovements are not . distressed ^y the removals.
Appropriate setbacks will be required and should be anticipated.
All existing utilities on or in the vicinity of the property should
be located prior to any grading or trenching operations These
precautions Jre the responsibility of the owner/contractor. MV
ENG?NEER?S§, ?NC. will not be held responsible for any damage or
distress.
MATERIALS
The fill soils shall consist of select materials, g^^^led s° that
at least 40 percent of the material passes the #4 sieve. The
material may be obtained from the excavation, a borrow pit, or by
mixing soils from one or more sources. The materials used shall
be free from vegetable matter and other deleterious substances,
oversized ro^Lks greater than two feet in maximum ^iajneter should
not be included in fills. Rocks greater than 12 inches (12 ) m
S?ame?er should be properly buried ten feet or more below grade
measured vertically. Rocks should be Pl^^!^„ P^J. Pf
geotechnical engineer or his representative to assure fil^^^"^ °f
all voids with compacted soils. Rocks greater than six inches (6 )
3
in diameter should not be allowed within the upper three feet of
all graded pads. Rock fills require a special inspection and
testing program under direct supervision of the project
geotechnical engineer or his representative.
If excessive vegetation, rocks, or soils with unacceptable Physical
characteristics are encountered these materials shall be disposed
of in waste areas designated on the plans or as directed by the
geotechnical engineer. No material of a perishable, spongy, or
otherwise unstable nature shall be used in the fills. If soils are
encountered during the grading operation which were not reported
in the preliminary soil investigation further testing will be
required to ascertain their engineering properties. Any special
treatment recommended in the preliminary or subsequent soil reports
not covered herein shall become an addendum to these
specifications.
Laboratory tests should be performed on representative soil samples
to be used as compacted fills in accordance with appropriate
testing procedures specified by ASTM in order to determine maximum
dry density and optimum moisture content of the fill soils.
PLACING. SPREADING. AND COMPACTION OF FILL MATERIAL
1. The selected fill material shall be placed in layers which shall
not exceed six inches (6") when compacted. Each layer shall be
spread evenly and shall be thoroughly blade-mixed during the
spreading to insure uniformity of material and moisture in each
layer.
2. When the moisture content of the fill material is below that
specified by the geotechnical engineer water shall be added until
the moisture content is near optimum as determined by the
geotechnical engineer to assure thorough bonding during the
compaction process. This is to take place even if the proper
density has been achieved without proper moisture.
3. When the moisture content of the fill material is above that
specified by the geotechnical engineer the fill material shall be
aerated by blading and scarifying or other satisfactory methods
until the moisture content is near optimum as determined by the
geotechnical engineer.
4. After each layer has been placed, mixed, and spread evenly it
shall be thoroughly compacted to not less than the recommended
minimum compaction requirements per specified maximum density in
accordance with ASTM D-1557-78. Compaction shall be by means of
tamping or sheepsfoot rollers, multiple-wheel pneumatic-tired
rollers, or other types of rollers. Rollers shall be of such
design that they will be able to compact the fill to the specified
density. Rolling each layer shall be continuous over its entire
area and the rollers shall make sufficient passes to obtain the
desired density. The entire area to be filled shall be compacted
to the specified density.
5. Fill slopes shall be compacted by means of sheepsfoot rollers
or other suitable equipment. Compacting of the slopes shall be
accomplished by backrolling the slopes in increments of three to
five feet (3'- 5') in elevation gain or by overfilling and cutting
back to the design configuration or other methods producing
satisfactory results.
If the method of achieving the required slope compaction selected
by the contractor fails to produce the necessary results, the
contractor shall rework or rebuild such slopes until the required
degree of compaction is obtained.
6. Field density tests shall be made in accordance with ASTM Method
D-1556-82 by the geotechnical engineer for approximately each foot
in elevation gain after compaction, but not to exceed two feet (2')
in vertical height between tests.
The geotechnical engineer shall be notified to test the fill at
regular intervals. If the tests have not been made after three
feet of compacted fill has been placed, the contractor shall stop
work on the fill until tests are made.
The location of the tests shall be spaced to give the best possible
coverage and shall be taken no farther than 100 feet apart. Tests
shall be taken on corner and terrace lots for each two feet (2')
in elevation gain. The geotechnical engineer may take additional
tests as considered necessary to check on the uniformity of
compaction. Where sheepsfoot rollers are used, the test shall be
taken in the compacted material below the disturbed surface. No
additional layers of fill shall be spread until the field density
tests indicate that the specified density has been obtained.
7. The fill operation shall be continued in six-inch (6") compacted
layers, as specified above, until the fill has been brought to the
finished slopes and grades as shown on the accepted plans.
SUPERVISION
Supervision by the geotechnical engineer or his representative
shall be made during the filling and compacting operation in order
to verify that the fill was constructed in accordance with the
preliminary soil report or agency requirements.
The specifications and soil testing of subgrade and basegrade
material for roads or other public property shall be done in
accordance with specifications of the governing agency unless
otherwise directed.
It should be understood that the contractor shall supervise and
direct the work and shall be responsible for all construction
means, methods, techniques, sequences, and procedures. The
contractor will be solely and completely responsible for conditions
at the job site, including safety of all persons and property
during the performance of the work. Intermittent or continuous
inspection by the geotechnical engineer is not intended to include
review of the adequacy of the contractor's safety measures in, on,
or near the construction site.
SEASONAL LIMITS
No fill material shall be placed, spread, or rolled during
unfavorable weather conditions. When the work is interrupted by
heavy rain, grading shall not be resumed until field tests by the
geotechnical engineer indicate that the moisture content and
density of the fill are as previously specified. In the event
that, in the opinion of the engineer, soils unsatisfactory as
foundation material are encountered, they shall not be incorporated
in the grading; disposition will be made at the engineer's
discretion.
UNIFIED SOIL CLASSIFICATION
Identifying Criteria
I. COARSE GRAINED (more
than 50% larger than
#200 sieve).
Gravels (more than 50%
larger than #4 sieve
but smaller than 3"),
non-plastic.
Symbol Soil Description
GW
GP
Gravel, well-graded gravel-
sand mixture, little or no
fines.
Gravel, poorly graded,
gravel-sand mixture, little
or no fines.
GM
GC
Gravel, silty, poorly graded,
gravel-sand-silt mixtures.
Gravel, clayey, poorly
graded, gravel-sand-clay
mixtures.
Sands (more than 50%
smaller than #4 sieve),
non-plastic.
SW
SP
SM
Sand, well-graded, gravelly
sands, little or no fines.
Sand, poorly graded gravelly
sand, little or no fines.
Sand, silty, poorly graded,
sand-silt mixtures.
SC Sand, clayey, poorly graded,
sand-clay mixtures.
II. FINE GRAINED (more than
50% smaller than #200
sieve).
Liquid Limit less
than 50. ML
CL
Silt, inorganic silt and
fine sand, sandy silt or
clayey-silt-sand mixtures
with slight plasticity.
Clay, inorganic clays of
low to medium plasticity,
gravelly clays, sandy clays,
silty clays, lean clays.
Unified Soil Classification
Fage 2
II. FINE GRAINED - continued
Liquid Limit greater
than 50.
III. HIGHLY ORGANIC SOILS
OL
MH
CH
OH
PT
Silt, organic, silts and
organic silts-clays of low
plasticity.
Silt, inorganic silts,
micaceous or diatomaceous,
fine sand or silty soils,
elastic silts.
Clay, inorganic, clays of
medium to high plasticity,
fat clays.
Clay, organic clays of
medium to high plasticity.
Peat, other highly organic
swamp soils.
ft
70-
60-
Fill (af)
terrace Deposit (Qt)
— Formational Rock (Td)
GEOLOGIC
CROSS-SECTIONS
-100
Ter race;>^*;»:L_,^-—2^ - -
Formational Rock (Td)
11
120
-80
IE.
lOOH
80
STREET ^'Fill_^(afj^^^^
-100
Formational Rock (Td)
-80
Scale 1=20
PLATE 2