HomeMy WebLinkAboutCDP 13-30; De Anda Residence; Coastal Development Permit (CDP) (7)GEpT-ECUNICAL UPDAIE.AND REV^LEW
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1409 TURQUOISE DRIVE
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W.O. 6612-A-SC OCTOBER 28, 2013
Geotechnical • Geologic • Coastal • Environmental
5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com
October 28, 2013
W.O. 6612-A-SC
Ms. Veronica De Anda
1409 Turquoise Drive
Carlsbad, California 92011
Subject: Geotechnical Update and Review, Proposed Developmentof 2425 Jefferson
Street (APN 155-140-41), Carlsbad, San Diego County, California
Dear Ms. De Anda:
In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the referenced
documents and reports (see Appendix - References) with respect to existing site
conditions, planned additional construction/innprovements and current code requirements.
Unless specifically superceded herein, the conclusions and recommendations presented
in the updated preliminary report (GSI, 2008) remain valid and applicable.
SITE CONDITIONS/PROPOSED DEVELOPMENT
The property is a roughly rectangular-shaped lot bounded by Jefferson Street on the east,
and adjacent residential properties to the south and north (under construction). Buena
Vista Lagoon is located along the western edge of the property. The property itself
consists of a relatively level pad area adjacent to Jefferson Street and a large natural slope,
which descends approximately 50 feet westward from the pad area to Buena Vista Lagoon.
Between the pad elevation of approximately 65 feet Mean Sea Level (MSL) and an
elevation of approximately 25 feet MSL, the slope descends at an approximate gradient of
272:1 (horizontal: vertical [h:v]). From an elevation of 25 feet MSL to the lagoon level, the
slope flattens to a gradient of approximately 472:1 (h:v).
Existing improvements to the property consist of remnants of an old foundation system
(concrete slab) and seepage pit, located in the northern portion ofthe existing pad area.
Vegetation on the property in the vicinity of the pad area consists of some small trees and
scattered grasses. Vegetation on the slope consists of primarily grasses. Drainage within
the property is predominately by sheet flow directed toward Jefferson Street or down the
slope face toward Buena Vista Lagoon. A site visit, completed in preparation of this report,
has evaluated that conditions have not substantially changed from those previously
evaluated.
It is our understanding that the existing foundation will be demolished. The proposed site
development will consist of preparing the pad for construction of a new, split level
residential structure, including a lower level pool on the west side ofthe structure. Cut and
fill grading techniques would be utilized to create design grades for the proposed
single-family residential structure and pool. It is anticipated that the residential
development will consist of a two-story structure with slab-on-grade and continuous
footings, utilizing masonry and/or wood-frame construction. Building loads are assumed
to be typical for this type of relatively light construction. The need for import soils is
unknown. It is anticipated that sewage disposal will be tied into the regional municipal
system.
PREVIOUS WORK
Previous geotechnical investigations and site work were completed by this office
(GSI; 1993, 2003), with an updated evaluation completed in 2008 (GSI, 2008). These
studies included surface observations and subsurface explorations, laboratory testing,
engineering and geologic analysis, and the development of recommendations for
earthwork and foundation design and construction, based on previously planned site
development schemes. Based on our review of previously proposed development, it
appears that site development concepts are similar to the currently proposed construction;
however, standards of practice and Codes change with time.
EARTHWORK CONSTRUCTION RECOMMENDATIONS
General
All grading should conform to the guidelines presented in Appendix Chapter J of the
2010 California Building Code ([2010 CBC], California Building Standards Commission
[2010]), the City of Carlsbad, and as recommended by this office, in GSI (2008). When
code references are not equivalent, the more stringent code should be followed. During
earthwork construction, all site preparation and the general grading procedures ofthe
contractor should be observed and the fill selectively tested by a representative(s) of GSI.
If unusual or unexpected conditions are exposed in the field, they should be reviewed by
this office and, if warranted, modified and/or additional recommendations will be offered.
All applicable requirements of local and national construction and general industry safety
orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act
should be met. It is GSI's understanding that the site is currently at, or very near, plan
grades, and that additional grading will likely consist of the surficial remedial
grading/processing recommended herein. Unless specifically superceded herein, the
conclusions and recommendations presented in GSI (2008) remain valid and applicable.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad _ October 28,2013
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REMEDIAL EARTHWORK
General
A review of GSI (2008) generally indicated that unsuitable surficial deposits of existing fill,
colluvium are to be removed to suitable formational soil and replaced with compacted fill.
For the uniform support of structures, a 5-foot thick blanket of compacted fill was
recommended. The minimum fill cap thickness may be revised to a minimum thickness
of 4 feet, or 2 feet below the bottom of footing, whichever is greater.
Alternatively, foundations for portions of the buildings foundation constructed within the
existing, west facing descending slope may be deepened into the underlying formational
soil, provided that all fill supporting the building pad is compacted to at least 95 percent
relative compaction per ASTM D-1557. All building foundations should satisfy the setback
requirements per Section 1808.7.2.
Swimming Pool
Based on the location ofthe pool, foundation support for the proposed swimming pool
should be derived from suitable, underlying bedrock material. Foundation systems
bearing on the existing sedimentary bedrock should consist of drilled pier foundations.
Recommendations for a pier and grade beam foundation system are presented herein.
However, the use of conventional foundations, sufficiently embedded into suitable
formational soil, may be considered upon further review.
Temporary Slopes
Temporary slopes for excavations greater than 4 feet but less than 20 feet in overall height
should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils, provided
water or seepage is not present. Temporary slopes, up to a maximum height of ±20 feet,
may be excavated at a 1:1 (h:v) gradient, or flatter, provided groundwater and/or running
sands are not exposed. Construction materials or soil stockpiles should not be placed
within 'H' of any temporary slope where 'H' equals the height of the temporary slope. All
temporary slopes should be observed by a licensed engineering geologist and/or
geotechnical engineer prior to worker entry into the excavation. Based on the exposed
field conditions, inclining temporary slopes to flatter gradients or the use of shoring may
be necessary if adverse conditions are observed. If temporary slopes conflict with property
boundaries, shoring or alternating slot excavations may be necessary. The need for
shoring or alternating slot excavations should be further evaluated.
Excavation Observation and Monitoring (All Excavations)
When excavations are made adjacent to an existing improvement (i.e., utility, wall, road,
building, etc.) there is a risk of some damage even if a well designed system of excavation
Ms. Veronica De Anda W.O. 6612-A-SC
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is planned and executed. We recommend, therefore, that a systematic program of
observations be made before, during, and after construction to determine the effects
(if any) of construction on existing improvements.
We believe that this is necessary for two reasons: First, if excessive movements (i.e., more
than y2-inch) are detected early enough, remedial measures can be taken which could
possibly prevent serious damage to existing improvements. Second, the responsibility for
damage to the existing improvement can be determined more equitably if the cause and
extent ofthe damage can be determined more precisely.
Monitoring should include the measurement of any horizontal and vertical movements of
the existing structures/improvements. Locations and type ofthe monitoring devices should
be selected prior to the start of construction. The program of monitoring should be agreed
upon between the project team, the site surveyor and the Geotechnical
Engineer-of-Record, prior to excavation.
Reference points on existing walls, buildings, and other settlement-sensitive improvements.
These points should be placed as low as possible on the wall and building adjacent to the
excavation. Exact locations may be dictated by critical points, such as bearing walls or
columns for buildings; and surface points on roadways or curbs near the top of the
excavation.
For a survey monitoring system, an accuracy of a least 0.01 foot should be required.
Reference points should be installed and read initially prior to excavation. The readings
should continue until all construction below ground has been completed and the
permanent backfill has been brought to final grade.
The frequency of readings will depend upon the results of previous readings and the rate
of construction. Weekly readings could be assumed throughout the duration of
construction with daily readings during rapid excavation near the bottom ofthe excavation.
The reading should be plotted by the Surveyor and then reviewed by the Geotechnical
Engineer. In addition to the monitoring system, it would be prudent for the Geotechnical
Engineer and the Contractor to make a complete inspection ofthe existing structures both
before and after construction. The inspection should be directed toward detecting any
signs of damage, particularly those caused by settlement. Notes should be made and
pictures should be taken where necessary.
It is recommended that all excavations be observed by the Geologist and/or Geotechnical
Engineer. Any fill which is placed should be approved, tested, and verified if used for
engineered purposes. Should the observation reveal any unforseen hazard, the Geologist
or Geotechnical Engineer will recommend treatment. Please inform GSI at least 24 hours
prior to any required site observation.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad , October 28, 2013
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Preliminarv Grading Plan Review
The preliminary grading plan prepared by Sampo Engineering, Inc. (SEI, 2013) has been
reviewed with respect to the intent of the soils report and current site conditions. Based
on our review, the plans appear to be in general accordance with the intent of the
geotechnical report, provided that the conclusions and recommendations presented in this
update evaluation are properly incorporated into the design and construction of the
project.
PRELIMINARY RECOMMENDATIONS - FOUNDATIONS/WALLS
General
Foundation design and construction shall be per the 2010 edition of the CBC (CBSC,
2010). Please note that GSI (2008) referenced the 2007 Code; however, while some
section numbers have changed from the 2007 Code to the 2010 CBC (see following
text/table, and CBSC [2010]), the geotechnical design parameters indicated in GSI (2008)
are the same. Additional recommendations regarding peak horizontal ground acceleration
and seismic surcharge are provided in the following sections.
Foundation design should be re-evaluated at the conclusion of site grading/remedial
earthwork for the as-graded soil conditions. Although not anticipated, revisions to these
recommendations may be necessary. In the event that the information concerning the
proposed development plan is not correct, or any changes in the design, location or
loading conditions of the proposed structure are made, the conclusions and
recommendations contained in this report shall not be considered valid unless the
changes are reviewed and conclusions of this report are modified or approved in writing
by this office.
The information and recommendations presented in this section are not meant to
supercede design by the project structural engineer or civil engineer specializing in
structural design. Upon request, GSI could provide additional input/consultation regarding
soil parameters, as related to foundation design. Unless specifically superceded herein,
the conclusions and recommendations presented in GSI (2008) are considered applicable.
Residence
Based on the expansive potential of onsite soils, recommendation presented in GSI (2008)
for conventional type foundation systems are provided. As indicated in GSI (2008)
remedial earthwork shall consist of undercutting the building pad and placing the entire
foundation system on a layer of compacted fill. Alternatively, foundations for portions of
the buildings foundation constructed within the existing, west facing descending slope may
be deepened into the underlying formational soil, provided that all fill supporting the
Ms. Veronica De Anda W.O. 6612-A-SC
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building pad is compacted to at least 95 percent relative compaction per ASTM D-1557.
All building foundations should satisfy the setback requirements per Section 1808.7.2.
Swimming Pool
Minor cuts and fills are anticipated in order to create the pool pad area. Based on the
location of the pool, foundation support for the proposed swimming pool should be
derived from suitable, underlying bedrock material using a pier and grade beam foundation
system. Recommendations for a pier and grade beam foundation system are presented
herein. The use of conventional type foundations may be considered, upon further review
and grading plan development.
Pool foundations will require embedment into suitable formational soil and require
setbacks to the face of slope per Section 1808.7.3 of the 2010 CBC (CBSC, 2010). Based
on the overall height ofthe slope, and the depth to suitable formation beneath the slope
face, setbacks on the order of 10 to 15 feet from the face of slope may be recommended.
Retaining Walls
Recommendations for the design and construction of retaining walls are presented in
GSI (2008). For perimeter retaining walls located within the existing slope areas,
foundation support may be derived from the underlying formational soil, as an alternative
to removal and recompaction, and supporting foundations on a fill blanket. For wall
foundations deepened into formation, all removal of unsuitable surficial soils shall be
performed behind the wall(s) and any fills shall be compacted to at least 95 percent relative
compaction per ASTM D-1557. All Wall foundations should satisfy the setback
requirements per Section 1808.7.2.
Seismic Shaking Parameters
Based on the site conditions, the following table summarizes the site-specific design
criteria obtained from the 2010 CBC (CBSC, 2010), Chapter 16 Structural Design,
Section 1613, Earthquake Loads. The computer program Seismic Hazard Curves and
Uniform Hazard Response Spectra, provided by the United States Geologic Survey
(U.S.G.S.) was utilized for seismic design values. The short spectral response utilizes a
period of 0.2 seconds. This application also produces seismic hazard curves, and uniform
hazard response spectra.
Ms. Veronica De Anda W.O. 6612-A-SC
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CBC SEISMIC DESIGN PARAMETERS
PARAMETER VALUE 2010 CBC
REFERENCE
Site Class D Table 1613.5.2
Spectral Response - (0.2 sec), S^ i.30g Figure 1613.5(1)
Spectral Response - (1 sec), S, 0.49g Figure 1613.5(2)
Site Coefficient, 1.0 Table 1613.5.3(1)
Site Coefficient, F^ 1.51 Table 1613.5.3(2)
Maximum Considered Earthquake Spectral
Response Acceleration (0.2 sec), S^g
1.30g Section 1613.5.3
(Eqn 16-36)
Maximum Considered Earthquake Spectral
Response Acceleration (1 sec), S^^
0.74g Section 1613.5.3
(Eqn 16-37)
5% Damped Design Spectral Response
Acceleration (0.2 sec), Spg
0.86g Section 1613.5.4
(Eqn 16-38)
5% Damped Design Spectral Response
Acceleration (1 sec), S^^
0.49g Section 1613.5.4
(Eqn 16-39)
GENERAL SEISMIC DESIGN PARAMETERS
Distance to Seismic Source
(Rose Canyon fault zone)
7.5 mi.
(12.0 km)
Upper Bound Earthquake
(Rose Canyon fault zone) Mw6.9**
Probabilistic Horizontal Ground Acceleration ([PHGA]
10% and 2% probability of exceedance in 50 years) 0.30g/0.39g
** International Conference of Building Officials (ICBO, 1998)
Conformance to the criteria above for seismic design does not constitute any kind of
guarantee or assurance that significant structural damage or ground failure will not occur
in the event of a large earthquake. The primary goal of seismic design is to protect life, not
to eliminate all damage, since such design may be economically prohibitive. Cumulative
effects of seismic events are not addressed in the 2010 CBC (CBSC, 2010) and regular
maintenance and repair following locally significant seismic events (i.e., M^^5.0) will likely
be necessary.
Peak Horizontal Ground Acceleration
A probabilistic peak horizontal ground acceleration (PHGA) of 0.30 g was evaluated forthis
site (GSI, 2008). This value was chosen as it corresponds to a 10 percent probability of
exceedence in 50 years (or a 475-year return period). Per the 2010 CBC (CBSC, 2010),
a PHGA of 0.39 was also evaluated. This value was chosen as it corresponds to a
2 percent probability of exceedence in 50 years (or a 2,475-year return period).
Ms. Veronica De Anda
2425 Jefferson Street, Carlsbad
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Seismic Surcharge for Retaining Walls
For engineered retaining walls that may pose ingress or egress constraints within 6 feet of
a structure, GSI recommends that such walls be evaluated for a seismic surcharge (in
general accordance with 2010 CBC requirements). The site walls in this category should
maintain an overturning Factor-of-Safety (FOS) of approximately 1.25 when the seismic
surcharge (increment), is applied. For restrained walls, the seismic surcharge should be
applied as a uniform surcharge load from the bottom of the footing (excluding shear keys)
to the top of the backfill at the heel of the wall footing. This seismic surcharge pressure
(seismic increment) may be taken as 15H where "H" for retained walls is the dimension
previously noted as the height of the backfill to the bottom of the footing. The resultant
force should be applied at a distance 0.6 H up from the bottom of the footing. For the
evaluation of the seismic surcharge, the bearing pressure may exceed the static value by
one-third, considering the transient nature of this surcharge. For cantilevered walls the
pressure should bean inverted triangular distribution using 15H. Reference for the seismic
surcharge is Section 1802.2 of the 2010 CBC. Please note this is for local wall stability
only.
The 15H is derived from a Mononobe-Okabe solution for both restrained cantilever walls.
This accounts for the increased lateral pressure due to shakedown or movement of the
sand fill soil in the zone of influence from the wall or roughly a 45° - cj)/2 plane away from
the back ofthe wall. The 15H seismic surcharge is derived from the formula:
Ph = % • ah • YtH
Where: Pj, = Seismic increment
ai, = Probabilistic horizontal site acceleration with a
percentage of "g"
Y, = total unit weight (115 to 125 pcf for site soils @ 90%
relative compaction).
H = Height ofthe wall from the bottom ofthe footing or point
of pile fixity.
SOIL MOISTURE TRANSMISSION CONSIDERATIONS
GSI has evaluated the potential for vapor or water transmission through the concrete floor
slab, in light of typical floor coverings and improvements. Please note that slab moisture
emission rates range from about 2 to 27 lbs/24 hours/1,000 square feet from a typical slab
(Kanare, 2005), while floor covering manufacturers generally recommend about
3 lbs/24 hours as an upper limit. The recommendations in this section are not intended
to preclude the transmission of water or vapor through the foundation or slabs.
Foundation systems and slabs shall not allow water or water vapor to enter into the
structure so as to cause damage to another building component or to limit the installation
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of the type of flooring materials typically used for the particular application (State of
California, 2013). These recommendations may be exceeded or supplemented by a water
"proofing" specialist, project architect, or structural consultant. Thus, the client will need
to evaluate the following in light of a cost vs. benefit analysis (owner expectations and
repairs/replacement), along with disclosure to all interested/affected parties. It should also
be noted that vapor transmission will occur in new slab-on-grade floors as a result of
chemical reactions taking place within the curing concrete. Vapor transmission through
concrete floor slabs as a result of concrete curing has the potential to adversely affect
sensitive floor coverings depending on the thickness of the concrete floor slab and the
duration of time between the placement of concrete, and the floor covering. It is possible
that a slab moisture sealant may be needed prior to the placement of sensitive floor
coverings if a thick slab-on-grade floor is used and the time frame between concrete and
floor covering placement is relatively short.
Considering the prior E.I. test results, and known soil conditions in the region, the
anticipated typical water vapor transmission rates, floor coverings, and improvements
(to be chosen by the Client and/or project architect) that can tolerate vapor transmission
rates without significant distress, the following alternatives are provided:
Concrete slabs, including garage slabs, should be a minimum of 5 inches thick.
• Concrete slab underlayment should consist of a 15-mil vapor retarder, or equivalent,
with all laps sealed per the 2010 CBC and the manufacturer's recommendation.
The vapor retarder should comply with the ASTM E 1745 - Class A criteria, and be
installed in accordance with ACI 302.1 R-04 and ASTM E 1643.
The 15-mil vapor retarder (ASTM E 1745 - Class A) shall be installed per the
recommendations ofthe manufacturer, including all penetrations (i.e., pipe, ducting,
rebar, etc.).
• Concrete slabs, including the garage areas, should be underlain by 2 inches of
clean, washed sand (SE >^ 30) above a 15-mil vapor retarder (ASTM E-1745 - Class
A, per Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations
ofthe manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The
manufacturer shall provide instructions for lap sealing, including minimum width of
lap, method of sealing, and either supply or specify suitable products for lap sealing
(ASTM E 1745), and per code.
ACI 302.1 R-04 (2004) states "If a cushion or sand layer is desired between the
vapor retarder and the slab, care must be taken to protect the sand layer from
taking on additional water from a source such as rain, curing, cutting, or cleaning.
Wet cushion or sand layer has been directly linked in the past to significant
lengthening of time required for a slab to reach an acceptable level of dryness for
floor covering applications." Therefore, additional observation and/ortesting will be
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necessary for the cushion or sand layer for moisture content, and relatively uniform
thicknesses, prior to the placement of concrete.
• For very low to low expansive soil conditions, the vapor retarder should be
underlain by 2 inches of sand (SE > 30) placed directly on the prepared, moisture
conditioned, subgrade and should be sealed to provide a continuous retarder under
the entire slab, as discussed above.
Concrete should have a maximum water/cement ratio of 0.50. This does not
supercede Table 4.3.1 of Chapter 4 of the ACI (2008) for corrosion or other
corrosive requirements. Additional concrete mix design recommendations should
be provided by the structural consultant and/or waterproofing specialist. Concrete
finishing and workablity should be addressed by the structural consultant and a
waterproofing specialist.
• Where slab water/cement ratios are as indicated herein, and/or admixtures used,
the structural consultant should also make changes to the concrete in the grade
beams and footings in kind, so that the concrete used in the foundation and slabs
are designed and/or treated for more uniform moisture protection.
The owner should be specifically advised which areas are suitable for tile flooring,
vinyl flooring, or other types of water/vapor-sensitive flooring and which areas are
not suitable for these types of flooring applications. In all planned floor areas,
flooring shall be installed per the manufactures recommendations.
Additional recommendations regarding water or vapor transmission should be
provided by the architect/structural engineer/slab or foundation designer and
should be consistent with the specified floor coverings indicated by the architect.
Regardless ofthe mitigation, some limited moisture/moisture vapor transmission through
the slab cannot be entirely precluded and should be anticipated. Construction crews may
require special training for installation of certain product(s), as well as concrete finishing
techniques. The use of specialized product(s) should be approved by the slab designer
and water-proofing consultant. A technical representative of the flooring contractor should
review the slab and moisture retarder plans and provide comment prior to the construction
of the foundation or improvement. The vapor retarder contractor should have
representatives onsite during the initial installation.
DRILLED PIER AND GRADE BEAM FOUNDATION RECOMMENDATIONS
Due to the proposed location of the swimming pool on the slope face, and in order to
minimize potential settlements, the pool foundation should be supported by a drilled,
cast-in-place, concrete pier and grade beam system (drilled piers). If desired, the entire
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building foundation may also be supported by drilled piers. Actual pier design should be
finalized by the project's structural engineer and the structural capacity ofthe pier(s) used.
The structural strength of the piers should be checked by the structural engineer or civil
engineer specializing in structural analysis.
The grade beam should be at a minimum of 24 inches by 24 inches in cross section and
supported by drilled piers, a minimum of 24 inches in diameter which are placed at a
maximum spacing of 8 feet on center and a minimum of 3 pier diameters apart and
supporting all structural columns. The design ofthe grade beam and piers should be in
accordance with the recommendations ofthe project structural engineer, and utilize the
following geotechnical parameters. Pier and any grade beam design and construction
shall minimally conform to the applicable sections contained in the 2010 CBC (CBSC,
2010).
Foundations Design Criteria - Drilled Piers
The drilled pier foundation for the pool should gain vertical support from friction and end
bearing in the existing terrace deposits underlying the site. Drilled piers for residential
foundations are intended to resist vertical and lateral loads due to imposed structural loads
and not provide lateral stability/stabilization of slopes. The drilled pier(s) should be at least
24 inches in diameter and should extend at least 10 feet into suitable terrace deposits. The
effects of pier groups should be evaluated when the preliminary foundation drawings are
made available. Soil parameters to be used in pier and grade beam design are provided
below. All the parameters provided are computed based on soil strength only, structural
strength of the piers should be checked by the structural engineer or civil engineer
specializing in structural analysis.
Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below
grade.
Passive Resistance: Passive earth pressure of 250 psf per foot of depth, to a
maximum value of 2,500 psf may be used to determine drilled
pier depth and spacing, provided that they meet or exceed the
minimum requirements stated above. To determine the total
lateral resistance, the contribution of the creep prone zone
above the point of fixity, to passive resistance, should be
disregarded. No contribution from soil/concrete friction on the
bottom of slabs should be included in passive calculations.
The upper 12 inches of passive resistance for the drilled piers
should be neglected unless confined by slabs or pavement.
Additional lateral resistance may be obtained from lateral pile
deflection. For a inch lateral pile deflection, a lateral load of
10 percent of vertical capacity can be utilized. A more refined
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lateral load capacity may be provided when the pier head
conditions (fixed, free), layout and elevations are provided by
the structural consultant and/or architect on this project.
Allowable Axial Capacity:
Shaft capacity : 450 psf applied over the surface area of the shaft within
bedrock deposits only. Note that some down drag of 250 psf
may be realized for settlement of fill soils up to 1 inch. For fill
settlements of less than 1 inch, use the full cohesion value of
the fill soil and consult with the geotechnical consultant.
Tip capacity: 3,500 psf. Assumes clean dense tip condition. Evaluated in
the field by the geotechnical consultant.
Pile/Fill Settlement: V2 inch between heavy and lighter loaded piles, and should be
less than V^t inch for post construction static and dynamic
settlement. Outside of the pile supported structures, the
potential settlement of any unmitigated fill left in place will likely
be more than what was noted previously for remediated fill.
CIDH (Drilled Pier) Construction
1. The excavation and installation of the drilled piers should be observed and
documented by the project geotechnical engineer to verify the recommended
depth.
2. The drilled hole(s) should be cased, specifically below the water table to prevent
caving. The bottom of the casing should be at least 4 feet below the top of the
concrete as the concrete is poured and the casing is withdrawn. Dewatering may
be required for concrete placement if significant seepage or groundwater is
encountered during construction. This should be considered during project
planning. The bottom ofthe drilled pier should be cleared of any loose or soft soils
before concrete placement.
3. The exact depths of pier(s) should be determined during the final precise grading
plan review.
4. Proper low slump concrete should be used and should be delivered through tremie
pipe. We recommend that concrete be placed through the tremie pipe immediately
subsequent to approved excavation and steel placement. Care should be taken to
prevent striking the walls of the excavations with the tremie pipe during concrete
placement. Vibration of concrete to reduce the potential for segregation should be
performed.
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5. All footing excavations should be observed and approved by the geotechnical
consultant prior to placement of concrete forms and reinforcement.
6. Drilled pier steel reinforcement cages should have spacers to allow for a minimum
spacing of steel from the side of the pier excavation. All reenforcing bars should be
epoxy coated due to the corrosive environment. The need for epoxy coated steel
in below grade walls and grade beams should be evaluated by a structural
consultant.
7. During pier placement, concrete should not be allowed to free fall more than 5 feet.
8. Concrete and steel used in the foundation should be tested by a qualified materials
testing consultant for strength, bar arrangement, and mix design.
Corrosion and Concrete Mix
Upon completion of grading, laboratory testing should be performed of site materials for
corrosion to concrete and corrosion to steel. Additional comments may be obtained from
a qualified corrosion engineer at that time. It is assumed by the project architect that all
steel will evaluate the need for epoxy-coated, or other, corrosion protection for pier steel
reinforcement.
ONSITE INFiLTRATION-RUNOFF RETENTION SYSTEMS
General
Onsite infiltration-runoff retention systems (OIRRS) may be required for Best Management
Practices (BMP's) or Low Impact Development (LID) principles for the project. To that end,
some guidelines should/must be followed in the planning, design, and construction of such
systems. Such facilities, if improperly designed or implemented without consideration of
the geotechnical aspects of site conditions, can contribute to flooding, saturation of
bearing materials beneath site improvements, slope instability, and possible concentration
and contribution of pollutants into the groundwater or storm drain and/or utility trench
systems.
A key factor in these systems is the infiltration rate (often referred to as the percolation rate)
which can be ascribed to, or determined for, the earth materials within which these
systems are installed. Additionally, the infiltration rate ofthe designed system (which may
include gravel, sand, mulch/topsoii, or other amendments, etc.) will need to be considered.
The project infiltration testing is very site specific, any changes to the location of the
proposed OIRRS and/or estimated size ofthe OIRRS, may require additional infiltration
testing. GSI anticipates that relatively impermeable terrace deposits will occur near the
surface at the conclusion of grading.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carisbad . October 28,2013
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Some of the methods which are utilized for onsite infiltration include percolation basins,
dry wells, bio-swale/bio-retention, permeable pavers/pavement, infiltration trenches, filter
boxes and subsurface infiltration galleries/chambers. Some of these systems are
constructed using native and import soils, perforated piping, and filter fabrics while others
employ structural components such as stormwater infiltration chambers and
filters/separators. Every site will have characteristics which should lend themselves to one
or more of these methods; but, not every site is suitable for OIRRS. In practice, OIRRS are
usually initially designed by the project design civil engineer. Selection of methods should
include (but should not be limited to) review by licensed professionals including the
geotechnical engineer, hydrogeologist, engineering geologist, project civil engineer,
landscape architect, environmental professional, and industrial hygienist. Applicable
governing agency requirements should be reviewed and included in design
considerations.
The following geotechnical guidelines should be considered when designing onsite
infiltration-runoff retention systems:
On a preliminary basis, the onsite soils are considered to fall into Hydrologic Soil
Group (HSG) "D" as defined in County of San Diego (2007).
It is not good engineering practice to allow water to saturate soils, especially near
slopes or improvements; however, the controlling agency/authority is now requiring
this for OIRRS purposes on many projects.
• Wherever possible, infiltration systems should not be installed within ±50 feet ofthe
tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where
H equals the height of slope).
Wherever possible, infiltrations systems should not be placed within a distance of
H/2 from the toes of slopes (where H equals the height of slope).
• Impermeable liners and subdrains should be used along the bottom of bioretention
swales/basins located within the influence of slopes such as exists onsite. Due to
the proximity of the planned bioretention basin to an adjacent, offsite slope and
retaining wall, the basin should be provided with an impermeable liner around the
entire basin. The 30 mil thick PVC liner should meet the following specifications:
specific gravity (ASTM D792); 120 (min.), tensile strength (ASTM D 882);
73 (Ib/in-width, min.), elongation at break (ASTM D D882): 380 (%min.), modulus
(ASTM D 882): 30 (Ib/in-width, min.), tear resistance (ASTM D1004): 30 (lb/in, min.).
The landscape architect should be notified of the location of the proposed OIRRS.
If landscaping is proposed within the OIRRS, consideration should be given to the
type of vegetation chosen and their potential effect upon subsurface improvements
(i.e., some trees/shrubs will have an effect on subsurface improvements with their
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad , October 28, 2013
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extensive root systems). Over-watering landscape areas above, or adjacent to, the
proposed OIRRS could adversely affect performance ofthe system.
Areas adjacent to, or within, the OIRRS that are subject to inundation should be
properly protected against scouring, undermining, and erosion, in accordance with
the recommendations of the design engineer.
If subsurface infiltration galleries/chambers are proposed, the appropriate size,
depth interval, and ultimate placement ofthe detention/infiltration system should be
evaluated by the design engineer, and be of sufficient width/depth to achieve
optimum performance, based on the infiltration rates provided. In addition, proper
debris filter systems will need to be utilized for the infiltration galleries/chambers.
Debris filter systems will need to be self cleaning and periodically and regularly
maintained on a regular basis. Provisions for the regular and periodic maintenance
of any debris filter system is recommended and this condition should be disclosed
to all interested/affected parties.
Infiltrations systems should not be installed within ±8 feet of building foundations
utility trenches, and walls, or a 1:1 (h:v) slope (down and away) from the bottom
elements of these improvements. Alternatively, deepened foundations and/or
pile/pier supported improvements may be used.
Infiltrations systems should not be installed adjacentto pavement and/or hardscape
improvements. Alternatively, deepened/thickened edges and curbs and/or
impermeable liners may be utilized in areas adjoining the OIRRS. Appropriate
setbacks from the bio retention area should be provided for settlement sensitive
improvements.
As with any OIRRS, localized ponding and groundwater seepage should be
anticipated. The potential for seepage and/or perched groundwater to occur after
site development should be disclosed to all interested/affected parties.
Installation of infiltrations systems should avoid expansive soils (E.I. >51) or soils
with a relatively high plasticity index (P.I. > 20).
Where permeable pavements are planned as part of the system, the site Traffic
Index (T.I.) Should be less than 25,000 Average Daily Traffic (ADT), as
recommended in Allen, et al. (2011).
Infiltration systems should be designed using a suitable factor of safety (FOS) to
account for uncertainties in the known infiltration rates (as generally required by the
controlling authorities), and reduction in performance overtime.
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2425 Jefferson Street, Carlsbad . October 28, 2013
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As with any OIRRS, proper care will need to be provided. Best management
practices should be followed at all times, especially during inclement weather.
Provisions for the management of any siltation, debris within the OIRRS, and/or
overgrown vegetation (including root systems) should be considered. An
appropriate inspection schedule will need to adopted and provided to all
interested/affected parties.
Any designed system will require regular and periodic maintenance, which may
include rehabilitation and/or complete replacement ofthe filter media (e.g., sand,
gravel, filter fabrics, topsoils, mulch, etc.) or other components utilized in
construction, so that the design life exceeds 15 years. Due to the potential for
piping and adverse seepage conditions, a burrowing rodent control program should
also be implemented onsite.
All or portions of these systems may be considered attractive nuisances. Thus,
consideration ofthe effects of, or potential for, vandalism should be addressed.
Newly established vegetation/landscaping (including phreatophytes) may have root
systems that will influence the performance of the OIRRS or nearby LID systems.
The potential for surface flooding, in the case of system blockage, should be
evaluated by the design engineer.
Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other
subsurface utilities) located within or near the proposed area of the OIRRS may
become saturated. This is due to the potential for piping, water migration, and/or
seepage along the utility trench line backfill. If utility trenches cross and/or are
proposed near the OIRRS, cut-off walls or other water barriers will need to be
installed to mitigate the potential for piping and excess water entering the utility
backfill materials. Planned or existing utilities may also be subject to piping of fines
into open-graded gravel backfill layers unless separated from overlying or adjoining
OIRRS by geotextiles and/or slurry backfill.
The use of OIRRS above existing utilities that might degrade/corrode with the
introduction of water/seepage should be avoided.
A vector control program may be necessary as stagnant water contained in OIRRS
may attract mammals, birds, and insects that carry pathogens.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad _ October 28, 2013
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DEVELOPMENT CRITERIA
Drainage
Adequate surface drainage is a very important factor in reducing the likelihood of adverse
performance of foundations and hardscape. Surface drainage should be sufficient to
mitigate ponding of water anywhere on the property, and especially near the structure.
Surface drainage should be carefully taken into consideration during fine grading,
landscaping, and building construction. Therefore, care should be taken that future
landscaping or construction activities do not create adverse drainage conditions. Positive
site drainage within the property should be provided and maintained at all times. Surface
water should be directed away from foundations, and not allowed to pond and/or seep into
the ground. In general, site drainage should conform to Section 1804.3 ofthe 2010 CBC.
Consideration should be given to avoiding construction of planters adjacent to structures
(i.e., buildings, pools, spas, etc.). Building pad drainage should be directed toward the
street or other approved area(s). Although not a geotechnical requirement, roof gutters,
down spouts, or other appropriate means may be utilized to control roof drainage. Down
spouts, or drainage devices should outlet a minimum of 5 feet from the structure or into a
subsurface drainage system. Areas of seepage may develop due to irrigation or heavy
rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas
of seepage develop, recommendations for minimizing this effect could be provided upon
request.
Erosion Control
Onsite earth materials have a moderate to high erosion potential. Consideration should
be given to providing hay bales and silt fences forthe temporary control of surface water,
from a geotechnical viewpoint.
Landscape Maintenance
Water has been shown to weaken the inherent strength of all earth materials. Only the
amount of irrigation necessary to sustain plant life should be provided. Over-watering the
landscape areas will adversely affect proposed site improvements. We would recommend
that any proposed open-bottom planters adjacent to proposed structures be eliminated
for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be
utilized. An outlet placed in the bottom ofthe planter, could be installed to direct drainage
away from structures or any exterior concrete flatwork. If planters are constructed adjacent
to structures, the sides and bottom of the planter should be provided with a moisture
barrier to prevent penetration of irrigation water into the subgrade. Provisions should be
made to drain the excess irrigation water from the planters without saturating the subgrade
below or adjacent to the planters. Plants selected for landscaping should be light weight,
deep rooted types that require little water and are capable of surviving the prevailing
climate. Jute-type matting or other fibrous covers may aid in allowing the establishment
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2425 Jefferson Street, Carlsbad . October 28, 2013
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of a sparse plant cover. Utilizing plants other than those recommended above will increase
the potential for perched water, staining, mold, etc., to develop. Consideration should be
given to the type of vegetation chosen and their potential effect upon surface
improvements (i.e., some trees will have an effect on concrete flatwork with their extensive
root systems). From a geotechnical standpoint leaching is not recommended for
establishing landscaping. If the surface soils are processed for the purpose of adding
amendments, they should be recompacted to 90 percent minimum relative compaction.
A rodent control program to prevent burrowing should be implemented.
Gutters and Downspouts
As previously discussed in the drainage section, the installation of gutters and downspouts
should be considered to collect roof water that may otherwise infiltrate the soils adjacent
to the structures. If utilized, the downspouts should be drained into PVC collector pipes
or other non-erosive devices (e.g., paved swales or ditches; below grade, solid tight-lined
PVC pipes; etc.), that will carry the water away from the house, to an appropriate outlet, in
accordance with the recommendations of the design civil engineer. Downspouts and
gutters are not a requirement; however, from a geotechnical viewpoint, provided that
positive drainage is incorporated into project design (as discussed previously).
Subsurface and Surface Water
Subsurface and surface water are not anticipated to affect site development, provided that
the recommendations contained in this report are incorporated into final design and
construction and that prudent surface and subsurface drainage practices are incorporated
into the construction plans. Perched groundwater conditions along zones of contrasting
permeabilities may not be precluded from occurring in the future due to site irrigation, poor
drainage conditions, or damaged utilities, and should be anticipated. Should perched
groundwater conditions develop, this office could assess the affected area(s) and provide
the appropriate recommendations to mitigate the observed groundwater conditions.
Groundwater conditions may change with the introduction of irrigation, rainfall, or other
factors.
Site Improvements
If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the
site, recommendations concerning the geological or geotechnical aspects of design and
construction of said improvements could be provided upon request. Pools and/or spas
should not be constructed without specific design and construction recommendations from
GSI, and this construction recommendation should be provided to all interested/affected
parties. This office should be notified in advance of any fill placement, grading ofthe site,
or trench backfilling after rough grading has been completed. This includes any grading,
utility trench and retaining wall backfills, flatwork, etc.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad ^ October 28,2013
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Tile Flooring
Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small
cracks in a conventional slab may not be significant. Therefore, the designer should
consider additional steel reinforcement for concrete slabs-on-grade where tile will be
placed. The tile installer should consider installation methods that reduce possible
cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane
(approved by the Tile Council of America/Ceramic Tile Institute) are recommended
between tile and concrete slabs on grade.
Additional Grading
This office should be notified in advance of any fill placement, supplemental regrading of
the site, or trench backfilling after rough grading has been completed. This includes
completion of grading in the street, driveway approaches, driveways, parking areas, and
utility trench and retaining wall backfills.
Footing Trench Excavation
All footing excavations should be observed by a representative of this firm subsequent to
trenching and prior to concrete form and reinforcement placement. The purpose of the
observations is to evaluate that the excavations have been made into the recommended
bearing material and to the minimum widths and depths recommended for construction.
If loose or compressible materials are exposed within the footing excavation, a deeper
footing or removal and recompaction ofthe subgrade materials would be recommended
at that time. Footing trench spoil and any excess soils generated from utility trench
excavations should be compacted to a minimum relative compaction of 90 percent, if not
removed from the site.
Trenching/Temporary Construction Backcuts
Considering the nature ofthe onsite earth materials, it should be anticipated that caving
or sloughing could be a factor in subsurface excavations and trenching. Shoring or
excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees
[except as specifically superceded within the text of this report]), should be anticipated.
All excavations should be observed by an engineering geologist or soil engineer from GSI,
prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA,
state, and local safety codes. Should adverse conditions exist, appropriate
recommendations would be offered at that time. The above recommendations should be
provided to any contractors and/or subcontractors, or homeowner(s), etc., that may
perform such work.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad _ October 28, 2013
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utility Trench Backfill
1. All interior utility trench backfill should be brought to at least 2 percent above
optimum moisture content and then compacted to obtain a minimum relative
compaction of 90 percent of the laboratory standard. As an alternative for shallow
(12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of
30 or greater may be utilized and jetted or flooded into place. Observation, probing
and testing should be provided to evaluate the desired results.
2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane
projected from the outside bottom edge of the footing, and all trenches beneath
hardscape features and in slopes, should be compacted to at least 90 percent of
the laboratory standard. Sand backfill, unless excavated from the trench, should
not be used in these backfill areas. Compaction testing and observations, along
with probing, should be accomplished to evaluate the desired results.
3. All trench excavations should conform to CAL-OSHA, state, and local safety codes.
4. Utilities crossing grade beams, perimeter beams, or footings should either pass
below the footing or grade beam utilizing a hardened collar or foam spacer, or pass
through the footing or grade beam in accordance with the recommendations ofthe
structural engineer.
SUMMARY OF RECOMMENDATIONS REGARDING
GEOTECHNICAL OBSERVATION AND TESTING
We recommend that observation and/or testing be performed by GSI at each of the
following construction stages:
During grading/recertification.
• During excavation.
During placement of subdrains or other subdrainage devices, prior to placing fill
and/or backfill.
• After excavation of building footings, retaining wall footings, and free standing walls
footings, prior to the placement of reinforcing steel or concrete.
Prior to pouring any slabs or flatwork, after presoaking/presaturation of building
pads and other flatwork subgrade, before the placement of concrete, reinforcing
steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor retarders (i.e., visqueen,
etc.).
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson street, Carlsbad , October 28, 2013
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During retaining wall subdrain installation, prior to backfill placement.
During placement of backfill for area drain, interior plumbing, utility line trenches,
and retaining wall backfill.
During slope construction/repair.
When any unusual soil conditions are encountered during any construction
operations, subsequent to the issuance of this report.
When any homeowner improvements, such as flatwork, spas, pools, walls, etc., are
constructed, prior to construction.
A report of geotechnical observation and testing should be provided at the
conclusion of each of the above stages, in order to provide concise and clear
documentation of site work, and/or to comply with code requirements.
OTHER DESIGN PROFESSIONALS/CONSULTANTS
The design civil engineer, structural engineer, post-tension designer, architect, landscape
architect, wall designer, etc., should review the recommendations provided herein,
incorporate those recommendations into all their respective plans, and by explicit
reference, make this report part of their project plans. This report presents minimum
design criteria for the design of slabs, foundations and other elements possibly applicable
to the project. These criteria should not be considered as substitutes for actual designs
by the structural engineer/designer. Please note that the recommendations contained
herein are not intended to preclude the transmission of water or vapor through the slab or
foundation. The structural engineer/foundation and/or slab designer should provide
recommendations to not allow water or vapor to enter into the structure so as to cause
damage to another building component, or so as to limit the installation of the type of
flooring materials typically used for the particular application.
The structural engineer/designer should analyze actual soil-structure interaction and
consider, as needed, bearing, expansive soil influence, and strength, stiffness and
deflections in the various slab, foundation, and other elements in order to develop
appropriate, design-specific details. As conditions dictate, it is possible that other
influences will also have to be considered. The structural engineer/designer should
consider all applicable codes and authoritative sources where needed. If analyses by the
structural engineer/designer result in less critical details than are provided herein as
minimums, the minimums presented herein should be adopted. It is considered likely that
some, more restrictive details will be required.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad _ October 28, 2013
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If the structural engineer/designer has any questions or requires further assistance, they
should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate
potential distress, the foundation and/or improvement's designer should confirm to GSI
and the governing agency, in writing, thatthe proposed foundations and/or improvements
can tolerate the amount of differential settlement and/or expansion characteristics and
other design criteria specified herein.
PLAN REVIEW
Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.),
should be reviewed by this office prior to construction, so that construction is in
accordance with the conclusions and recommendations of this report. Based on our
review, supplemental recommendations and/or further geotechnical studies may be
warranted.
LIMITATIONS
The materials encountered on the project site and utilized for our analysis are believed
representative ofthe area; however, soil and bedrock materials vary in character between
excavations and natural outcrops or conditions exposed during mass grading. Site
conditions may vary due to seasonal changes or other factors.
Inasmuch as our study is based upon our review and engineering analyses and laboratory
data, the conclusions and recommendations are professional opinions. These opinions
have been derived in accordance with current standards of practice, and no warranty,
either express or implied, is given. Standards of practice are subject to change with time.
GSI assumes no responsibility or liability for work or testing performed by others, or their
inaction; or work performed when GSI is not requested to be onsite, to evaluate if our
recommendations have been properly implemented. Use of this report constitutes an
agreement and consent by the user to all the limitations outlined above, notwithstanding
any other agreements that may be in place. In addition, this report may be subject to
review by the controlling authorities. Thus, this report brings to completion our scope of
services for this portion ofthe project. All samples will be disposed of after 30 days, unless
specifically requested by the client, in writing.
Ms. Veronica De Anda W.O. 6612-A-SC
2425 Jefferson Street, Carlsbad , October 28, 2013
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The opportunity to be of service is greatly appreciated. If you have any questions
concerning this report, or if we may be of further assistance, please do not hesitate to
contact any of the undersigned.
Respectfully submitted^xO
GeoSoils, Inc. / 3L§'
\ Cerii
Robert G. Crisman
Engineering Geologist, CE
RGC/DWS/JPF/jh
Attachment: Appendix - References
Distribution: (4) Addressee
//(3^3'rr-
tit "\ln
David W. Skelly cf::;:^^^
Civil Engineer, RCE 4785^;^:;^^^
Ms. Veronica De Anda
2425 Jefferson Street, Carlsbad
File:e:\wp9\6600\6612a.upg GeoSoils, Inc.
W.O. 6612-A-SC
October 28, 2013
Page 23
APPENDIX
REFERENCES
Allen, v., Connerton, A., and Carlson, C, 2011, Introduction to Infiltration Best
Management Practices (BMP), Contech Construction Products, Inc., Professional
Development Series, dated December.
American Concrete Institute, 2004, Guide for concrete floor and slab construction:
reported by ACI Committee 302; Designation ACI 302.1 R-04, dated March 23.
American Concrete Institute Committee 318, 2008, Building code requirements for
structural concrete (ACI 318-08) and commentary, dated January.
American Concrete Institute Committee 360, 2006, Design of slabs-on-ground
(ACI 360R-06).
American Concrete Institute Committee 302, 2004, Guide for concrete floor and slab
construction, ACI 302.1 R-04, dated June.
American Concrete Institute Committee on Responsibility in Concrete Construction, 1995,
Guidelines for authorities and responsibilities in concrete design and construction
in Concrete International, vol 17, No. 9, dated September.
American Society for Testing and Materials, 2004, Standard specification for water vapor
retarders used in contact with soil or granular fill under concrete slabs.
, 1998, Standard practice for installation of water vapor retarder used in contact with
earth or granular fill under concrete slabs. Designation: E 1643-98 (Re-approved
2005).
, 1997, Standard specification for plastic water vapor retarders used in contact with
soil or granular fill under concrete slabs. Designation: E 1745-97 (Reproved 2004).
Beery Group Architecture, 2013, Architectural plans for: the De Anda residence. Job No.
1309, dated August 19.
California Building Standards Commission, 2010, California Building Code, California Code
of Regulations, Title 24, Part 2, Volume 2 of 2, Based on the 2009 International
Building Code, 2010 California Historical Building Code, Title 24, Part 8; 2010
California Existing Building Code, Title 24, Part 10.
GeoSoils, Inc.
Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and wiilis, C.J., 2003, The revised 2002
California probalistic seismic hazard maps, dated June,
http://www.conversation.ca.gov/cqs/rghm/psha/fault parameters/pdf/documents
/2002_ca_hazardmaps.pdf
County of San Diego, Department of Planning and Land Use, 2007, Low impact
development (LID) handbook, stormwater management strategies,
dated December 31.
GeoSoils, Inc., 2008, Updated preliminary geotechnical evaluation, APN 155-140-41,
Carlsbad, San Diego County, California, W.O. 5763-A-SC, dated October 15.
, 2003, Update preliminary geotechnical evaluation, APNs 155-140-37 and
155-140-38, City of Carlsbad, San Diego County, California, W.O. 3213-A-SC, dated
September 18.
, 1993, Preliminary geotechnical evaluation. Parcel 155-140-09, Carlsbad, California,
W.O. 1624-SD, dated November 2.
International Conference of Building Officials, 1998, Maps of known active fault near-source
zones in California and adjacent portions of Nevada.
Kanare, H., 2005, Concrete floors and moisture, Portland Cement Association, Skokie,
Illinois.
Sampo Enginering, Inc, 2013, Preliminary grading plan for: De Anda residence, APN 155-
14-41 Job No. 13-109, dated August 14.
State of California, 2013, Civil Code, Title 7, Division 2, Section 895, et seq.
United States Geological Survey, 2012, 2008 Earthquake Hazards Program,
2008 interactive deaggregations (Beta), Earthquake Hazards Program;
http://eqint.cr.usgs.qov/deaqgint/2008/.
, 2011, Seismic hazard curves and uniform hazard response spectra, NEHRP Option,
Version 5.1.0, dated February 10.
, 2007, Working Group on California Earthquake Probabilities, 2008, The uniform
California earthquake rupture forecast, version 2 (UCERF2); U.S. Geological Sun/ey
Open-File Report 2007-1437, and California Geological Survey Special Report 203,
http://pubs.usgs.qov/of/2007/1437/.
Ms. Veronica De Anda _ Appendix
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