HomeMy WebLinkAboutCT 04-14A; TRAILS END; GEOTECHNICAL DISCUSSION AND REVIEW; 2014-03-20341
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5741 Palmer Way Carlsbad, California 92010 (760) 438-3155 FAX (760) 931JJN51o7w2Ieosoilsinc.com
ME MORAN D UeNu Ljr-VELOPMENT
ENGINEERING
DATE: March 20, 2014 W.O. 6635-A -SC
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Attention:
FROM:
Donna Drive, LLC
5505 Canca De Golf
Rancho Santa Fe, California 920
Mr. Nick Biancomano
John P. Franklin, CEG 1340
Andrew T. Guatelli, GE 2320
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SUBJECT: Geotechnical Discussion and Review, Retaining Wall Drainage and
Permeable Pavement Design/Construction, Proposed, Trails End
Development, Northwest Corner of the Donna Drive and Carlsbad
Village Drive Intersection, Carlsbad, San Diego County, California
References: 1. "Precise Grading Plans For: Trails End Development, CT 04-14," 5 Sheets, Job No. 13136,
dated December 31, 2013, by Masson & Associates, Inc.
2. "Geotechnical Update Evaluation, Proposed Trails End Development, Northwest Corner
of the Donna Drive and Carlsbad Village Drive Intersection, Carlsbad, San Diego County,
California," W.O. 6635-A-SC, dated November 27, 2013, by GeoSoils, Inc.
In accordance with your request and authorization, GeoSoils, Inc. (GSI) is presenting this
geotechnical discussion and review memorandum regarding City comments related to wall
design/construction, and the use of permeable pavements onsite.
Based on our review of the referrenced plans, our referenced geotechnical report, and information
presented and discussed at a team meeting on February 7,2014, the following comments, and/or
additional recommendations are provided:
Retaining Walls
PILO Design and construction recommendations for retaining walls are presented in Reference No. 2.
From a geotechnical viewpoint, retaining wallback drains may be tied into the planned private
storm drain system, provided that wall drains connect into the top of (i.e., drop down into) the
storm drain pipe. Construction sequencing that includes tying wall drainage into an existing private
storm drain (i.e., tapping into an existing pipe), will require the use of a lean (2- to 3-sack slurry)
as backfill around the wall backdrain drop inlet. The civil engineer should show the
backdrain/tightline transition, and tightline outlets going into the storm drains on the plans. GSI
should review these plans prior to construction.
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Permeable Pavement
The permeable pavement specifications shown on Reference No. 1 generally appear suitable for
the intended use, with the following comments and/or additional recommendations:
Based on our review of Reference No. 2, site soils may generally be classified as USCS soil
type SM (silty sand). Based on a review of Plan Sheet 3, Orco Detail Sheet SN-2, a
I minimum base course thickness of 8 inches (for the purpose of fire access roads) should
be used.
All pavement subgrade should be compacted to at least 95 percent relative compaction,
per ASTM 0-1557.
I 3. The minimum diameter 4 inch PVC drain pipe shown on Orco Detail Sheet COM-7
(concrete grade beam detail) should be lowered, and placed at the compacted fill/natural
soil subgrade contact, at the base of the permeable drain rock.
I 4. The deepened curb detail, shown on Plan Sheet 2 of Reference No. 1, superceds the Orco
Detail Sheet COM-1, shown on Plan Sheet 3, where applicable All drainpipes should be
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sized, sloped and design/approved by the project civil consultant.
Soil subgrade supporting "Grasspave" paving systems should be compacted to at least 95
percent relative compaction per ASTM 0-1557.
The thickness of the underlying road base, shown on the Grasspave 2 Detail on Plan Sheet
4 of Reference No. 1 should be at least 8 inches, and consist of new base material.
I 7. Due to a potential permeability contrast between the "grasspave" section and the "Orco"
permeable pavement section (located south of Lot 8), a concrete cutoff wall, extendirjg at
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least 3-4 inches into soil subgrade, with a perforated subdrain located on the "Orco"
pavement side of the cut off wall is recommended. This subdrain may be discharged into
the nearby bioretention basin.
I 8. Similar to retaining walls, the civil engineer should show the subdrain/tightline transition,
and tightliné outlets going into the bioretention basin on the plans. GSI should review these
plans prior to construction.
I Deepened Curb Detail, Sheet 2
I The detail should be modified to show that the slip trench is no more than 4 inches wide, and
backfihled with grout. The sheet plastic should be specified as HDPE.
LE Closure
Unless specifically superceded herein or in our forthcoming report, or by the currently applicable
Building Code, the conclusions and recommendations presented in Reference No. 1 remain
pertinent and applicable, and should be appropriately implemented during project planning,
design, and construction.
I Donna Drive, LLC W.O. 6635-A-SC
Trails End Development, Carlsbad March 20, 2014
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The conclusions and recommendations presented herein 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.
Donna Drive, LLC W.O. 6635-A-SC
Trails End Development, Carlsbad March 20, 2014
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GEOTECHNICAL UPDATE EVALUATION
PROPOSED TRAILS END DEVELOPMENT
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5505 CANCADE GOLF
RANCHO SANTA FE, CALIFORNIA 92091
W.O.6635-A-SC DECEMBER 11, 2013
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I Geotechnical' Geologic. Coastal • Environmental
5741 Palmer Way • Carlsbad, California 92010 • (760)438-3155 • FAX (760)931-0915 • www.geosoilsinc.com
December 11, 2013
W.O. 6635-A-SC
Donna Drive, LLC
5505 Canca De Golf
Rancho Santa Fe, California 92091
Attention: Mr. Nick Biancomano
Subject: Geotechnical Update Evaluation, Proposed Trails End Development,
Northwest Corner of the Donna Drive and Carlsbad Village Drive Intersection,
Carlsbad, San Diego County, California
Dear Mr. Biancomano:
In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the referenced
documents and reports (see Appendix A - References) with respect to existing site
conditions, the currently planned residential development, and current code requirements.
Unless specifically superceded herein, the conclusions and recommendations presented
in GSI (2003 and 2005 [see Appendix A]) remain valid and applicable, and should be
appropriately implemented during the balance of project design and construction.
PROPOSED DEVELOPMENT
Based on the current precise grading plans (see Plate 1), prepared by Masson and
Associates, Inc. ([M&A], 2013), GSI understands that the subject site will be prepared to
receive seven (7) residential duplex structures with an associated private cul-de-sac street,
underground utilities, Concrete Masonry Unit (CMU) retaining walls, and Portland Cement
Concrete (PCC) flatwork. Two (2) community areas (i.e., park site and tot lot) are also
planned. It appears that cut and fill grading will be necessary to achieve the design grades
with maximum planned cuts and fills on the order of approximately 20 feet and 10 feet,
respectively. Grade differentials will betransitioned through the construction of graded cut
and fill slopes, and CMU retaining walls. Maximum height graded cut and fill slopes will
be on the order of 13 feet and 17 feet (including walls), respectively and be inclined at
gradients of 2:1 (horizontal: vertical [h:v]) or flatter. Retaining wall heights will be
approximately 6 feet or less. GSI anticipates that the private cul-de-sac street will be
surfaced with asphaltic concrete (AC), and/or Portland Concrete Cement (PCC) pavement.
Based on our review, pools, spas are not planned at this time.
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The planned residential structures will be two stories and would likely utilize wood frames
I with concrete slab-on-grade floors. Building loads are currently unknown, but assumed
to be typical for such relatively light structures. Sewage disposal will be tied into the
municipal system. Storm water runoff will be treated onsite prior to introduction into the
I municipal system.
I PREVIOUS WORK
GSI performed a preliminary geotechnical evaluation for previous site design concepts in
I 2003 (GSI, 2003). Based on the body of work performed in conjunction with this
investigation, GSI concluded that the then-proposed development concepts were feasible
from a geotechnical standpoint. The most significant geotechnical constraints to the
I formerly proposed development included potentially compressible soils up to
approximately 3 feet thick, the presence of soils with very low to perhaps medium
expansion potentials, and the potential for the site to experience moderate to strong
I, ground shaking from a nearby earthquake.
In 2005, GSI performed ageotechnical review of grading plans fora similar design concept
which included 14 split-level single-family residential structures, a community area, and
associated underground utility and landscape improvements. Based on our review, GSI
concluded that the grading concept reviewed in preparation of GSI (2005) was feasible
I from a geotechnical standpoint. However, we indicated that global stability analyses of
retaining walls and slopes may be warranted based on our review of retaining walls details
and design assumptions.
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UPDATED SEISMICITY EVALUATION
The acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999) has been
incorporated into EQFAULT (Blake, 2000a). EQFAULT is a computer program developed
I by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using
digitized California faults as earthquake sources.
I The program estimates the closest distance between each fault and a given site. If a fault
is found to be within a user-selected radius, the program estimates peak horizontal ground
acceleration that may occur at the site from an upper bound (formerly "maximum credible
I earthquake"), on that fault. Upper bound refers to the maximum expected ground
acceleration produced from a given fault. Site acceleration (g) was computed by
one user-selected acceleration-attenuation relation that is contained in EQFAULT. Based
I on the EQFAULT program, a peak horizontal ground acceleration from an upper bound
event on the offshore segment of the Newport - Inglewood fault may be on the order of
0.55g. This is within the range of accelerations previously indicated in GSI (2003). The
computer printouts of pertinent portions of the EQFAULT program are included within
Appendix B.
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Historical site seismicity was evaluated with the acceleration-attenuation relationship of
I Bozorgnia, Campbell, and Niazi (1999), and the computer program EQSEARCH
(Blake, 2000b, updated to December 2012). This program performs a search of the
historical earthquake records for magnitude 5.0 to 9.0 seismic events within a
I 100-kilometer radius, between the years 1800 through December 2012. Based on the
selected acceleration-attenuation relationship, a peak horizontal ground acceleration is
estimated, which may have affected the site during the specific event listed. Based on the
I available data and the attenuation relationship used, the estimated maximum (peak) site
acceleration during the period 1800 through December 2012 was about 0.23 g. A historic
earthquake epicenter map and a seismic recurrence curve are also estimated/generated
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from the historical data. Computer printouts of the EQSEARCH program are presented in
Appendix B.
I A probabilistic seismic hazards analysis was performed using the 2008 Interactive
Deaggregations (Beta [2012 update]) Seismic Hazard Analysis tool available at the USGS
website (https://geohazards.usgs.gov/deaggnit/2008/) which evaluates the site specific ' probabilities of exceedance for selected spectral periods. Based on a review of these data,
and considering the relative seismic activity of the southern California region, a
probabilistic horizontal ground acceleration (PHGA) of 0.47 g and 0.26 g were calculated.
I These values were chosen as they correspond to a 2 and 10 percent probability of
exceedance in 50 years, respectively. The calculated values are within the range typical
for the southern California region. Probabilistic vertical ground acceleration may be
.I assumed as 50 percent of the PHGA. Printouts from this analysis are also included in
Appendix B.
UPDATED SEISMIC DESIGN PARAMETERS
I Based on the site conditions, the following table summarizes the updated site-specific
design criteria obtained from the 2010 CBC (CBSC, 2010), Chapter 16 Structural Design,
Section 1613, Earthquake Loads. The computer program "U.S. Seismic Design Maps,
I provided by the United States Geologic Survey (USGS, 2013) was utilized for design
(http://geohazards.usgs.gov/designmaps/us/application.php). The short spectral response
utilizes a period of 0.2 seconds.
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2010 CBC SEISMIC DESIGN PARAMETERS
PARAMETER VALUE _F 2010. C BC
REFERENCE
Site class D Table 1613.5.2
Spectral Response - (0.2 sec), S 1.237g Figure 1613.5(1)
Spectral Response - (1 sec), S, 0.468g Figure 1613.5(2)
Site coefficient, F. 1.005 Table 1613.5.3(1)
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2010 CBCSEISMIC DESIGN PARAMETERS
PA RAMETER VALUE 2010 CBC
REFERENCE
Site Coefficient, F,, 1.532 Table 1613.5.3(2)
Maximum Considered Earthquake Spectral 1.243g Section 1613.5.3
Response Acceleration (0.2 sec), Sms (Eqn 16-36)
Maximum Considered Earthquake Spectral 0.716g Section 1613.5.3
Response Acceleration (1 sec), Sm, (Eqn 16-37)
5% Damped Design Spectral Response 0.829g Section 1613.5.4
Acceleration (0.2 sec), (Eqn 16-38)
506 Damped Design Spectral Response 0.478g Section 1613.5.4
Acceleration (1 sec), S,, (Eqn 16-39)
I GENERAL SEISMICDESIGN PARAMETERS
Distance to Seismic Source (Newport-Inglewood 6.1 mi./9.8 km" [Offshore segment])
Upper Bound Earthquake (Newport-Inglewood M 6.9 2VM [OffshoreSegment])
Probabilistic Horizontal Ground Acceleration ([PHGA] 0.26g/0.47g 10% /2% probability of exceedance in 50 years)
- Blake (2000a)
- International Conference of Building Officials (ICBO, 1998)
- Cao, et al. (2003)
SLOPESTABILITY
Based on our review Of GSI (2003) and this evaluation, permanent graded slopes,
p constructed from the onsite materials (i.e., native, or properly compacted fills), to the
heights, grades and configurations shown on the plans (see Plate 1) are considered
grossly and surficially stable, assuming proper surface drainage, landscaping, regular and
I periodic care and maintenance, and normal rainfall. The natural slope upon which the site
is located is generally considered stable given the absence of adverse structures, the soil
strengths evaluated (GSI, 2003), and no evidence of historic instability. Site earth materials
I are also considered erosive. As such, positive surface drainage practices and vegetative
covering should be maintained throughout the life of the project. Temporary slopes for
construction are discussed in subsequent sections of our report. Slope stability should be
I re-evaluated at the 40-scale grading plan review stage.
As indicated in GSI (2005), our slope stability did not include "a review of the details or
I assumptions regarding the parameters utilized in retaining wall design (i.e., design
parameters, surcharge, etc.)." As such, this should be further evaluated during the
40-scale grading plan stage. All fill and cut slopes should be reviewed during grading by
a certified engineering geologist, or the consultant of record.
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UPDATED PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS
Based on our review of the data acquired from previous work (GSI; 2003, 2005), a review
of the precise grading plan (M&A, 2013), and our recent geotechnical analyses, it is our
I opinion that the subject site is suitable for the currently proposed residential development
from a geotechnical engineering and geologic viewpoint, provided that the
recommendations presented in the following sections are incorporated into the design and
I construction phases of site development. The primary geotechnical concerns with respect
to the proposed development and improvements are:
I . Earth materials characteristics and depth to competent bearing material.
Uniform support for the residential foundations.
On-going expansion and corrosion potentials of the onsite soils.
I . Permanent and temporary slope stability.
Erosiveness of site earth materials.
Potential for perched water during and following site development.
I . Perimeter conditions and planned improvements near the property boundary.
Regional seismic activity.
I The recommendations presented herein consider these as well as other aspects of the site.
The engineering analyses performed concerning site preparation and the
recommendations presented herein have been completed using the information provided
I and obtained and reviewed during previous site studies (GSI; 2003, 2005).
In the event that any significant changes are made to proposed site development, the
I conclusions and recommendations contained in this report shall not be considered valid
unless the changes are reviewed and the recommendations of this report verified or
modified in writing by this office. Foundation design parameters are considered
I preliminary until the foundation design, layout, and structural loads are provided to this
office for review.
UPDATED PRELIMINARY EARTHWORK CONSTRUCTION RECOMMENDATIONS
I General
All grading should conform to the guidelines presented in Appendix Chapter J of the
I 2010 California Building Code ([2010 CBC], California Building Standards Commission
[2010]), the City of Carlsbad, and be in accordance with recommendations presented in
GSI (2003), unless specifically superceded herein. When code references are not
I equivalent, the more stringent code should be followed. During earthwork construction,
all site preparation and the general grading procedures of the contractor should be
observed and the fill selectively tested by a representative (s) of GSI. If unusual or
I 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
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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.
Based on our review of GSI (2003), removals of compressible surficial soils are generally
anticipated to be on the order of 1½ to 3 feet across the site. Transition lots and cut lots
should be overexcavated to provide for a minimum of 3 feet of engineered fill below pad
grade elevation or 18 inches of engineered fill beneath the lowest foundation element
(whichever is greater) The maximum to minimum fill thickness across the building pads
should not exceed a ratio of 3:1 (maximum: minimum). The bottom of the overexcavations
should be constructed such that it slopes away from the structure, preferably toward the
private cul-de-sac street, or other approved outlet. The need for subdrains is not
anticipated, but cannot be precluded at this time. Additional grading recommendations
and criteria are presented in Appendix C. The final geoetchncial review of the plans should
be accompanied by multiple civil generated cross sections through the project to assist
with locating cut/fill transitions as well as limit the amount of fill variation under residential
buildings
Perimeter Conditions
It should be noted that the 2010 CBC (CBSC, 2010) indicates that removals of unsuitable
soils be performed across all areas to be graded, under the purview of the grading permit,
not just within the influence of the planned residential structures. Relatively deep removals
may also necessitate a special zone of consideration, on perimeter/confining areas. This
zone would be approximately equal to the depth of removals, if removals cannot be
performed onsite or offsite. On a preliminary basis, any planned settlement-sensitive
improvements located within approximately 1½ and 3 feet from the subdivision boundary
or existing easements would require deepened foundations or additional reinforcement by
means of ground improvement or specific structural design, for perimeter conditions
discussed above. Otherwise, these improvements may be subject to distress and a
reduced serviceable lifespan. This will also require proper disclosure to any owners and
all interested/affected parties should this condition exist at the conclusion of grading.
Based on the available subsurface data and our review of M&A (2013), the planned
retaining walls within approximately 11/2 to 3 feet from the subdivision boundary may
require deepened footings into the unweathered terrace deposits for adequate lateral
bearing support, or alternatively using pier supports, i.e., drilled cast-in-place piers.
Temporary Slopes
Temporary slopes for excavations greater than 4 feet but less than 20 feet in overall height
I should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils, provided
groundwater, seepage, and/or running sands are not present. Temporary slopes, up to
a maximum height of ±20 feet, may be excavated at a 1:1 (h:v) gradient, or flatter,
I provided groundwater, seepage, and/or running sands are not exposed. Construction
materials or soil stockpiles should not be placed within 'H' of any temporary slope where
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'H' equals the height of the temporary slope. All temporary slopes should be observed by
I 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
I temporary slopes conflict with property boundaries, shoring or alternating slot excavations
may be necessary. The need for shoring or alternating slot excavations would be further
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evaluated during the grading plan review stage.
Excavation Observation and Monitoring (All Excavations)
I 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
is planned and executed. We recommend, therefore, that a systematic program of
I observations be made before, during, and after construction to determine the effects
(if any) of construction on existing improvements.
I We believe that this is necessary for two reasons: First, if excessive movements (i.e., more
than ½-inch) are detected early enough, remedial measures can be taken which could
possibly prevent serious damage to existing improvements. Second, the responsibility for
I damage to the existing improvement can be determined more equitably if the cause and
extent of the damage can be determined more precisely.
I Monitoring should include the measurement of any horizontal and vertical movements of
the existing structures/improvements. Locations and type of the monitoring devices should
be selected prior to the start of construction. The program of monitoring should be agreed
I upon between the project team, the site surveyor and the Geotechnical
Engineer-of-Record, prior to excavation.
I 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
I columns for buildings; and surface points on roadways or curbs near the top of the
excavation.
I 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
I permanent backfill has been brought to final grade.
The frequency of readings will depend upon the results of previous readings and the rate
I of construction. Weekly readings could be assumed throughout the duration of
construction with daily readings during rapid excavation near the bottom of the excavation.
The reading should be plotted by the Surveyor and then reviewed by the Geotechnical
I Engineer. In addition to the monitoring system, it would be prudent for the Geotechnical
Engineer and the Contractor to make a complete inspection of the existing structures both
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before and after construction. The inspection should be directed toward detecting any
I signs of damage, particularly those caused by settlement. Notes should be made and
pictures should be taken where necessary.
I 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
I or Geotechnical Engineer will recommend treatment. Please inform GSI at least 24 hours
prior to any required site observation.
PRELIMINARY FOUNDATION RECOMMENDATIONS
I General
The foundation design and construction recommendations, presented herein, are based ' on the laboratory testing previously performed in conjunction with GSI (2003) and recent
engineering evaluations. The following preliminary foundation design and construction
recommendations are presented as minimum criteria from a geotechnical engineering
I viewpoint. Previous expansion index testing performed on representative samples of the
onsite soils indicates expansion indices (E.l.) ranging between less than 5 and 19. This
corresponds to a very low expansion potential. However, soils with low to perhaps
I medium expansion potentials (E.l. = 21 to 90) may occur within the site. Such soil, if
present, would require the use of foundations designed in accordance with
Sections 1808.6.1 or 1808.6.2 of the 2010 CBC.
I GSI is providing preliminary design and construction recommendations for conventional
foundation and slab-on-grade floor systems overlying non-detrimentally expansive soil
I conditions (P.I.<15, E.l.<20), as well as post-tensioned and mat foundation
recommendations for low and medium expansive soil conditions (P.1. <15, E.I. range of 21
to 90). In addition, GSI is providing post-tension and mat foundation systems for
I non-detrimentally expansive soil conditions if higher foundation performance is expected
by the developer.
I This report presents minimum design criteria for the design of foundations, concrete
slab-on-grade floors, and other elements possibly applicable to the project. These criteria
should not be considered as substitutes for actual designs by the structural engineer.
I Recommendations by the project's design-structural engineer or architect, which may
exceed the geotechnical consultant's recommendations, should take precedence over the
following minimum requirements. The foundation systems recommended herein may be
I used to support the proposed residences provided they are entirely founded in engineered
fill tested and approved by GSI. The proposed foundation systems should be designed
and constructed in accordance with the guidelines contained in the 2010 CBC.
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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 structures 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
I modified or approved in writing by this office.
The information and recommendations presented in this section are not meant to
I supercede design by the project structural engineer or civil engineer specializing in
structural design. Upon request, GSI could provide additional input/consultation regarding
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soil parameters, as they relate to foundation design.
General Foundation Design (Very Low Expansive Soil, E.l.<20, P.1<15)
I 1. The foundation systems should be designed and constructed in accordance with
guidelines presented in the 2010 CBC.
l 2. An allowable bearing value of 1,500 psf may be used for the design of footings that
maintain a minimum width of 12 inches and a minimum depth of 12 inches (below
the lowest adjacent grade) and are founded entirely into properly engineered fill.
I This value may be increased by 20 percent for each additional 12 inches in footing
embedment to a maximum value of 2,500 psf. These values may be increased by
one-third when considering short duration seismic or wind loads. Isolated pad
I footings should have a minimum dimension of at least 24 inches square and a
minimum embedment of 24 inches below the lowest adjacent grade into properly
engineered fill. Foundation embedment excludes any landscaped zones, concrete
I slabs-on-grade, and/or slab underlayment.
Passive earth pressure may be computed as an equivalent fluid having a density of
I 250 pcf, with a maximum earth pressure of 2,500 psf for footings founded into
properly engineered fill. Lateral passive pressures for shallow foundations within
2010 CBC setback zones should be reduced following a review bythe geotechnical
I engineer unless proper setbacks can be established.
For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a
I concrete to soil contact when multiplied by the dead load.
When combining passive pressure and frictional resistance, the passive pressure
I component should be reduced by one-third.
All footing setbacks from slopes should comply with Figure 1808.7.1 of the
I 2010 CBC. GSI recommends a minimum horizontal setback distance of 7 feet as
measured from the bottom, outboard edge of the footing to the slope face.
I 7. Footings for structures adjacent to retaining walls should be deepened so as to
extend below a 1:1 projection from the heel of the wall should this condition occur.
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Alternatively, walls may be designed to accommodate structural loads from ' buildings or appurtenances as described in the "Retaining Wall" section of this
report.
I 8. Code-compliant foundations may be conventional-type if soils within the influence
of the foundation have an E.I. of 20 or less and a P.I. less than 15. Otherwise
post-tension or mat foundation systems should be used, in accordance with
Sections 1808.6.1 or 1808.6.2 of the 2010 CBC.
All interior and exterior column footings should be tied to the perimeter wall footings
I in at least one direction, for very low expansive soil conditions, and in two directions
for medium expansive soil conditions. The base of the reinforced grade beam
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should be at the same elevation as the adjoining footings.
Provided the recommendations in this report are properly followed, foundation
systems should be minimally designed to accommodate a total settlement of 11/2
I inches and a differential settlement of at least 1-inch in a 40-foot horizontal span
(angular distortion= 1/480).
PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS
The following foundation construction recommendations are presented as a minimum
criteria from a soils engineering viewpoint. On a preliminary basis, conventional
foundations may be used to support the planned residential structures provided the soils
within the upper 10 feet of pad grade and 7 feet outside the perimeter of the building
possess an E.I. of 20 or less and a P.I. less than 15. Otherwise, post-tension or mat
foundations would be necessary to mitigate expansive soil effects in accordance with
Sections 1808.6.1 or 1808.6.2 of the 2010 CBC.
Conventional Foundations -Expansion Index of 20 or Less with a Plasticity Index Less
Than 15
Exterior and interior footings should be founded into properly engineered fill at a
minimum depth of 12 or 18 inches below the lowest adjacent grade for one- or
two-story floor loads, respectively. For one- and two-story floor loads, footing
widths should be 12 and 15 inches, respectively. Isolated, exterior column and
panel pads, or wall footings, should be at least 24 inches square, and founded at
a minimum depth of 24 inches into properly compacted fill. All footings should be
minimally reinforced with four No. 4 reinforcing bars, two placed near the top and
two placed near the bottom of the footing. Foundation reinforcement layout, design
and evaluations should be performed by the project structural engineer.
2. All interior and exterior column footings, and perimeter wall footings, should be tied
together via grade beams in at least one direction, for very low expansive soil
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conditions (two directions for low to medium expansive soils). The grade beam
I should be at least 12 inches square in cross section, and should be provided with
a minimum of one No.4 reinforcing bar at the top, and one No.4 reinforcing bar at
the bottom of the grade beam. The base of the reinforced grade beam should be
I at the same elevation as the adjoining footings. Foundation reinforcement layout,
design and evaluations should be performed by the project structural engineer.
I 3. A grade beam, reinforced as previously recommended and at least 12 inches
square, should be provided across large (garage) entrances. The base of the
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reinforced grade beam should be at the same elevation as the adjoining footings.
4. A minimum concrete slab-on-grade thickness of 5 inches is recommended.
I 5. Concrete slabs should be reinforced with a minimum of No. 3 reinforcement bars
placed at 18-inch on centers, in two horizontally perpendicular directions (i.e., long
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axis and short axis).
All slab reinforcement should be supported to, ensure proper mid-slab height
positioning during placement of the concrete. "Hooking" of reinforcement is not an
I acceptable method of positioning.
Specific slab subgrade pre-soaking is not required for very low expansive soil
I conditions. However, moisture conditioning the upper 12 inches of the slab
subgrade to at least optimum moisture should be considered.
I 8. Soils generated from footing excavations to be used onsite should be compacted
to a minimum relative compaction of 90 percent of the laboratory standard
(ASTM D 1557), whether the soils are to be placed inside the foundation perimeter
I or in the yard/right-of-way areas. This material must not alter positive drainage
patterns that direct drainage away from the structural areas and toward the street.
I 9. Reinforced concrete mix design should conform to "Exposure Class Cl" in
Table 4.3.1 of ACI-318-08 since concrete would likely be exposed to moisture.
Post-Tensioned Foundations
Post-tension foundations may be used to mitigate the damaging effects of expansive soils
on the planned building foundations and slab-on-grade floors. They may also be used for
increased performance of foundations constructed on non-detrimentally expansive soils.
The post-tension foundation designer may elect to exceed these minimal
recommendations to increase slab stiffness performance. Post-tension (PT) design may
be either ribbed or mat-type. The latter is also referred to as uniform thickness foundation
(UTF). The use of a UTF is an alternative to the traditional ribbed-type. The UTF offers a
reduction in grade beams (i.e., that method typically uses a single perimeter grade beam
and possible "shovel" footings), but has a thicker slab than the ribbed-type.
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The information and recommendations presented in this section are not meant to
supercede design by a registered structural engineer or civil engineer qualified to perform
post-tensioned design. Post-tensioned foundations should be designed using sound
engineering practice and be in accordance with local and 2010 CBC requirements. Upon
I request, GSI can provide additional data/consultation regarding soil parameters as related
to post-tensioned foundation design.
I From a soil expansion/shrinkage standpoint, a common contributing factor to distress of
structures using post-tensioned slabs is a "dishing" or "arching" of the slabs. This is caused
by the fluctuation of moisture content in the soils below the perimeter of the slab primarily
I due to onsite and offsite irrigation practices, climatic and seasonal changes, and the
presence of expansive soils. When the soil environment surrounding the exterior of the
slab has a higher moisture content than the area beneath the slab, moisture tends to
I migrate inward, underneath the slab edges to a distance beyond the slab edges referred
to as the moisture variation distance. When this migration of water occurs, the volume of
the soils beneath the slab edges expands and causes the slab edges to lift in response.
I This is referred to as an edge-lift condition. Conversely, when the outside soil environment
is drier, the moisture transmission regime is reversed and the soils underneath the slab
edges lose their moisture and shrink. This process leads to dropping of the slab at the
l edges, which leads to what is commonly referred to as the center lift condition. A
well-designed, post-tensioned slab having sufficient stiffness and rigidity provides a
resistance to excessive bending that results from non-uniform swelling and shrinking slab
I subgrade soils, particularly within the moisture variation distance, near the slab edges.
Other mitigation techniques typically used in conjunction with post-tensioned slabs consist
of a combination of specific soil pre-saturation and the construction of a perimeter "cut-off'
I wall grade beam. Soil pre-saturation consists of moisture conditioning the slab subgrade
soils prior to the post-tension slab construction. This effectively reduces soil moisture
migration from the area located outside the building toward the soils underlying the
I post-tension slab. Perimeter cut-off walls are thickened edges of the concrete slab that
impedes both outward and inward soil moisture migration.
Slab Subgrade Pre-Soaking
Pre-moistening of the slab subgrade soil is recommended. The moisture content of the
I subgrade soils should be equal to or greater than optimum moisture to a depth equivalent
to the perimeter grade beam or cut-off wall depth in the slab areas (typically 12, 18,24, and
30 inches for very low to low, medium, high, and very high expansive soil conditions,
I respectively).
Pre-moistening and/or pre-soaking should be evaluated by the soils engineer 72 hours
prior to vapor retarder placement. In summary:.
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EXPANSION PAD SOIL MOISTURE CONSTRUCTION SOIL MOISTURE
POTENTIAL METHOD RETENTION
Very Low Upper 12 inches of pad at or Wetting and/or Periodically wet or cover with
(El. = 0-20) above soil optimum moisture reprocessing plastic after trenching.
Evaluation 72 hours prior to
placement of concrete.
Low Upper 12 inches of pad soil Wetting and/or Periodically wet or cover with
(E.I. = 21-50) moisture conditioned to reprocessing plastic after trenching.
2 percent over optimum Evaluation 72 hours prior to
placement of concrete.
Medium Upper 18 inches of pad soil Berm and flood or Periodically wet or cover with
(El. = 51-90) moisture conditioned to wetting and reprocessing plastic after trenching.
2 percent over optimum or Evaluation 72 hours prior to
1.2 times optimum, whichever placement of concrete.
is greater.
Perimeter Cut-Oft Walls
Perimeter cut-off walls should be at least 12 or 18 inches deep for very low to low and
medium expansive soil conditions, respectively. The cut-off walls may be integrated into
the slab design or independent of the slab. The cut-off walls should be a minimum of
6 inches thick (wide). The bottom of the perimeter cut-off wall should be designed to resist
tension, using cable or reinforcement per the structural engineer.
Post-Tensioned Foundation Design
The following recommendations for design of post-tensioned slabs have been prepared
in general compliance with the requirements of the recent Post Tensioning Institute's
(PTl's) publication titled "Design of Post-Tensioned Slabs on Ground, Third Edition"
(P11, 2004), together with it's subsequent addendums (PTI, 2008).
Soil Support Parameters
The recommendations for soil support parameters have been provided based on the
typical soil index properties for soils that are very low to medium in expansion potential.
The soil index properties are typically the upper bound values based on our experience
and practice in the southern California area. The following table presents suggested
minimum coefficients to be used in the Post-Tensioning Institute design method.
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Thornthwaite Moisture Index -20 inches/year
Correction Factor for Irrigation 20 inches/year
Depth to Constant Soil Suction 7 feet
Constant soil Suction (pf) 3.6
Moisture Velocity 0.7 inches/month
Plasticity Index (P.1.) <15-40
Based on the above, the recommended soil support parameters are tabulated below:
EXPANSION POTENTIAL DESIGN
PARAMETERS F VERY LOW TO LOW MEDIUM
(E.I. = 0-501
em center lift 9.0 feet 8.7 feet
em edge lift 5.2 feet 4.5 feet
y center lift 0.4 inches 0.5 inches
ym edge lift 0.7 inch 1.3 inch
Bearing Value 1,500 psf 1,000 psf
Lateral Pressure 250 psf 175 psf
Subgrade Modulus (k) 100 pci/inch 85 pci/inch
Minimum Perimeter
(2) Footing Embedment 12 inches 18 inches
Internal bearing values within the perimeter of the post-tension slab may be increased to 2,000 psf
(1,500 pcf for medium expansive soils) for a minimum embedment of 12 inches, then by 20 percent for
each additional foot of embedment to a maximum of 2,500 psf (2,000 pcf for medium expansive soils).
As measured below the lowest adjacent compacted subgrade surface without landscape layer or
sand underlayment.
Notes: Post tensioned slab design should also be evaluated with respect to potential differential
settlements provided in this report.
The use of open bottomed raised planters adjacent to foundations will require more onerous design
parameters.
The parameters are considered minimums and may not be adequate to represent all
expansive soils and site conditions such as adverse drainage and/or improper
landscaping and maintenance. The above parameters are applicable provided the
structure has positive drainage that is maintained away from the structure. In addition, no
trees with significant root systems are to be planted within 15 feet of the perimeter of
foundations. Therefore, it is important that information regarding drainage, site
maintenance, trees, settlements, and effects of expansive soils be passed on to future all
interested/affected parties. The values tabulated above may not be appropriate to account
for possible differential settlement of the slab due to other factors, such as excessive
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settlements. If a stiffer slab is desired, alternative Post-Tensioning Institute ([PTI] third
1 edition) parameters may be recommended.
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Mat Foundations
In lieu of using a post-tensioned foundation to resist expansive soil effects, the Client may
consider a mat foundation which uses steel bar reinforcement instead of post-tensioned
I cables. The structural engineer may supersede the following recommendations based on
the planned building loads and use. WRI (Wire reinforcement institute) methodologies for
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design may be used.
Mat Foundation Design
' The design of mat foundations should incorporate the vertical modulus of subgrade
reaction. This value is a unit value for a 1-foot square footing and should be reduced in
accordance with the following equation when used with the design of larger foundations.
I This is assumes that a compacted fill layer with an average relative compaction of
90 percent of the laboratory (ASTM D 1557), overlying dense terrace deposits underlies
the footings.
-KR _k[fl
where: Ks = unit subgrade modulus
I KR = reduced subgrade modulus
B = foundation width (in feet)
I The modulus of subgrade reaction (K3) and effective plasticity index (P1) to be used in mat
foundation design for various expansive soil conditions are presented in the following
table.
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VERY LOW TO LOW EXPANSION MEDIUM EXPANSION
(E.I. = 050) (E.I. = 51-90)
I Kg =100 pci/inch, P1 <15 I Kg =85 pci/inch, P1 = 25
Reinforcement bar sizing and spacing for mat slab foundations should be provided by the
structural engineer. Mat slabs may be uniform thickness foundations (UTF) or may
incorporate the use of edge footings for moisture cut-off barriers as recommended herein
for post-tension foundations. Edge footings should be a minimum of 6 inches thick. The
bottom of the edge footing should be designed to resist tension, using reinforcement per
the structural engineer. The need and arrangement of interior grade beams (stiffening
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beams) will be in accordance with the structural consultant's recommendations. The ' recommendations for a mat type of foundation assume that the soils below the slab are
compacted fill overlying dense, unweathered bedrock. The parameters herein are to
mitigate the effects of expansive soils and should be modified to mitigate the effects of the
total and differential settlements reported earlier in this report.
Specific pre-moistening/pre-soaking and moisture testing of the slab subgrade are
I recommended for expansive soil conditions (E.I. > 20 and P.I. of 15 or greater). Slab
subgrade moisture conditioning/pre-soaking should conform to the recommendations
previously provided for post-tension foundation systems.
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AS-GRADED SOIL EXPANSION AND CORROSION
Upon completion of grading, additional testing of soils (including import materials) for
expansion index and corrosion to concrete and metals should be performed prior to the
construction of utilities and foundations.
SOIL MOISTURE TRANSMISSION CONSIDERATIONS
GSI has evaluated the potential for vapor or water transmission through the concrete floor
I slab, in light of typical floor coverings and improvements. Please note that slab moisture
emission rates range from about 2 to 27 Ibs/ 24 hours/1,000 square feet from a typical slab
(Kanare, 2005), while floor covering manufacturers generally recommend about
I 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
I structure so as to cause damage to another building component or to limit the installation
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
I "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
I 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
I 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
I coverings if a thick slab-on-grade floor is used and the time frame between concrete and
floor covering placement is relatively short.
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Considering the E. I. test results presented herein, and known soil conditions in the region,
I 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
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rates without significant distress, the following alternatives are provided:
Concrete slabs should be a minimum of 5 inches thick.
I . Concrete slab underlayment should consist of a 10-15-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 -
I Class A criteria, and be installed in accordance with ACI 302.1R-04 and ASTM
E 1643.
The 10- to 15-mil vapor retarder (ASTM E 1745 - Class A) shall be installed per the
recommendations of the manufacturer, including aU penetrations (i.e., pipe, ducting,
rebar, etc.).
Concrete slabs, including the garage areas, shall be underlain by 2 inches of clean,
washed sand (SE > 30) above a 15- mil vapor retarder (ASTM [-1745 - Class A, per
Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations of the
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/or testing will be
necessary for the cushion or sand layer for moisture content, and relatively uniform
thicknesses, prior to the placement of concrete.
The vapor retarder shall be underlain by 2 inches of sand (SE > 30) placed directly
on the prepared, moisture conditioned, very low expansive subgrade and should
be sealed to provide a continuous retarder under the entire slab, as discussed
above. If low or medium expansive soils are present within the influence of the
foundation and slab-on-grade floor, the vapor retarder should be underlain by a
capillary break consisting of at least 4 inches of clean crushed gravel with a
maximum dimension of 3/4 inch (less than 5 percent passing the No. 200 sieve).
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Concrete should have a maximum water/cement ratio of 0.50. This does not
I 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
I finishing and workablity should be addressed by the structural consultant and a
waterproofing specialist.
I . 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
I are designed and/or treated for more uniform moisture protection.
The owner(s) should be specifically advised which areas are suitable fortileflooring,
I vinyl flooring, or other types of water/vapor-sensitive flooring and which are not
suitable. In all planned floor areas, flooring shall be installed per the manufactures
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recommendations.
Additional recommendations regarding water or vapor transmission should be
provided by the architect/structural engineer/slab or foundation designer and I should be consistent with the specified floor coverings indicated by the architect.
Regardless of the mitigation, some limited moisture/moisture vapor transmission through
the slab 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 foundations
or improvements. The vapor retarder contractor should have representatives onsite during
the initial installation.
WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS
Conventional Retaining Walls
The design parameters provided below assume that either very low expansive soils
(typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite
materials with an expansion index up to 50 are used to backfill any retaining wall. The type
of backfill (i.e., select or native), should be specified by the wall designer, and clearly
shown on the plans. Building walls, below grade, should be water-proofed. The
foundation system forthe proposed retaining walls should be designed in accordance with
the recommendations presented in this and preceding sections of this report, as
appropriate. Footings should be embedded a minimum of 18 inches below the lowest
adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width.
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There should be no increase in bearing for footing width. As indicated previously, any
retaining wall footings near the perimeter of the site will likely need to be deepened into
unweathered terrace deposits for adequate vertical and lateral bearing support.
Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided
upon request, and would be based on site specific conditions.
Restrained Walls
Any retaining walls that will be restrained prior to placing and compacting backfill material
or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid
pressure (EFP) of 55 pounds per cubic foot (pcf) and 65 pcf for select and very low to low
expansive native backfill, respectively. The design should include any applicable
surcharge loading. For areas of male or re-entrant corners, the restrained wall design
should extend a minimum distance of twice the height of the wall (2H) laterally from the
corner.
Cantilevered Walls
The recommendations presented below are for cantilevered retaining walls up to 10 feet
high. Design parameters for walls less than 3 feet in height may be superceded by County
of San Diego regional standard design. Active earth pressure may be used for retaining
wall design, provided the top of the wall is not restrained from minor deflections. An
equivalent fluid pressure approach may be used to compute the horizontal pressure
against the wall. Appropriate fluid unit weights are given below for specific slope gradients
of the retained material. These do not include other superimposed loading conditions due
to traffic, structures, seismic events or adverse geologic conditions. When wall
configurations are finalized, the appropriate loading conditions for superimposed loads can
be provided upon request.
For preliminary planning purposes, the structural consultant/wall designer should
incorporate the surcharge of traffic on the back of retaining walls where vehicular traffic
could occur within horizontal distance "H" from the back of the retaining wall (where "H"
equals the wall height). The traffic surcharge may be taken as 100 psf/ft in the upper 5 feet
of backfill for light truck and cars traffic. This does not include the surcharge of parked
vehicles which should be evaluated at a higher surcharge to account for the effects of
seismic loading. Equivalent fluid pressures for the design of cantilevered retaining walls
are provided in the following table:
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SURFACE SLOPE OF EQUIVALENT EQUIVALENT
RETAINED MATERIAL FLUID WEIGHT P.C.F. FLUID WEIGHT P.C.F.
(HORIZONTAL VERTICAL) (SELECT BACKFILL)2> (NATIVE BACKFILL)3>
IF-Level(')38 45
2tol 1 55 60 11
Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without
a slope for a distance of 2H behind the wall, where H is the height of the wall.
SE > 30, P.I. < 15, E.I. < 21, and < 10% passing No. 200 sieve.
E.I. = 0 to 50, SE > 30, P.I. < 15, E.I. < 21, and < 15% passing No. 200 sieve.
Seismic Surcharge
For engineered retaining walls, GSI recommends that the 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 be an 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 - /2 plane away from
the back of the wall. The 15H seismic surcharge is derived from the formula:
Ph = /8 • a• yH
Where: Ph = Seismic increment
ah = Probabilistic horizontal site acceleration with a percentage of
= total unit weight (115 to 125 pcf for site soils @ 90% relative
compaction).
H = Height of the wall from the bottom of the footing or point of pile
fixity.
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Retaining Wall Backfill and Drainage
Positive drainage must be provided behind all retaining walls in the form of gravel wrapped
in geofabric and outlets. A backdrain system is considered necessary for retaining walls
I that are 2 feet or greater in height. Details 1, 2, and 3, present the backdrainage options
discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS
pipe encased in either Class 2 permeable filter material or 3/4-inch to 1½-inch gravel
I wrapped in approved filter fabric (Mirafi 140 or equivalent). For select backfill, the filter
material should extend a minimum of 1 horizontal foot behind the base of the walls and
upward at least 1 foot. For native backfill that has up to E.I. = 50, continuous Class 2
I permeable drain materials should be used behind the wall. This material should be
continuous (i.e., full height) behind the wall, and it should be constructed in accordance
with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited
1 access and confined areas, (panel) drainage behind the wall may be constructed in
accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain).
Materials with an expansion index (El.) potential of greater than 50 should not be used as
U backfill for retaining walls. For more onerous expansive situations, backfill and drainage
behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail
Clean Sand Backfill).
— Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than
± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, I only, in walls higher than 2 feet, is not recommended. The surface of the backfill should
be sealed by pavement or the top 18 inches compacted with native soil (E.l. !~ 50). Proper
I surface drainage should also be provided. For additional mitigation, consideration should
be given to applying a water-proof membrane to the back of all retaining structures. The
use of a waterstop should be considered for all concrete and masonry joints.
Wall/Retaining Wall Footing Transitions
I Site walls are anticipated to be founded on footings designed in accordance with the
recommendations in this report. Should wall footings transition from cut to fill, the
structural consultant/wall designer may specify either:
A minimum of a 2-foot overexcavation and recompaction of cut materials for a
distance of 2H, from the point of transition.
Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints
or crack control joints) such that a angular distortion of 1/360 for a distance of 2H
I on either side of the transition may be accommodated. Expansion joints should be
placed no greater than 20 feet on-center, in accordance with the structural
engineer's/wall designer's recommendations, regardless of whether or not transition
conditions exist. Expansion joints should be sealed with aflexible, non-shrink grout.
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Structural footing or
settlement-sensitive improvement
i— Provide surface drainage via an
(1) Waterproofing / engineered V-ditch (see civil plans
membrane / for details)
CMU or / 2:1 NO slope
reinforced-concrete
wall Slope or level
±12 inches - — 12ihe •. :: ..
•.. : .:
••. ___ •. : :•(2)Gra...:. •.•••
Proposed grade
sloped to drain : . ...•.: \ per precise civil .. Native backfill
drawings \
.
/ \ (5) Weep hole .. ........... ...
\\\\-\\\> ... •.- :.
•: 1:1 NO or flatter
backcut to be
Footing and wall ........: ;. properly benched
design by other
(6) Footing
Waterproofing membrane.
Gravel: Clean, crushed, 3/4 to iY2 inch.
Filter fabric: Mirati 140N or approved equivalent.
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient sloped to suitable, approved outlet point (perforations down).
Weep hole: Minimum 2-inch diameter placed at 20-toot centers along the wall and placed
3 inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
Footing: If bench is created behind the tooting greater than the tooting width, use
level till or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
G4Jic. RETAINING WALL DETAIL - ALTERNATIVE A Detail 1
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[1 Structural footing or
(1) Waterproofing settlement-sensitive improvement -
membrane (optional) Provide surface drainage via engineered
V-ditch (see civil plan details)
CMU or 24 NO slope reinforced-concrete
wall
6 inches
-
T . .:.. ....: . ••(2).Composite' :.
I . ....-.. .. ........ ..... ... . drain .........:.• \\
(5) Weep hole—
,- Proposed grade
....•.•...
- (3) Filter fabri Native backfill / sloped to drain
/ per precise civil •.: :.. : . .. .
drawings (4) Pipe 11 NO or flatter
backcut to be
Footing and wall properly benched
design by others - . . (6) 1 cubic foot of
3/4-inch crushed rock
(7) Footing
(1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent.
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Drain: Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain
6200 or J-drain 200 or equivalent for waterproofed walls (all perforations down).
Filter fabric: Mirafi 14ON or approved equivalent; place fabric flap behind core.
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with
minimum of 1 percent gradient to proper outlet point (perforations down).
Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed
3 inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
Gravel: Clean, crushed, % to iY2 inch.
Footing: If bench is created behind the footing greater than the footing width, use
level fill or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
G4. Siza. RETAINING WALL DETAIL - ALTERNATIVE B Detail 2
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(1) Waterproofing
membrane
CMU or
reinforced-concrete
wall
I 4
I ±12 inches
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(5) Weep hole —
H 1— Proposed grade
sloped to drain
J per precise civil
drawinqs
Footing and wall
design by others
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Structural footing or
settlement-sensitive improvement
Provide surface drainage
21 NO slope
minimum:. .. •. . . \\
(8) Native backfill
(6) Clean
. sand backfill
- 1:1 NO or flatter
: backcut to be (3) Filter fabric properly benched
(2) Gravel
Heel
dth (4) Pipe
I
(7) Footing
Waterproofing membrane: Liquid boot or approved masticequivalent.
Gravel: Clean, crushed, 3/4 to iY2 inch.
Filter fabric: Mirafi 140N or approved equivalent.
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient to proper outlet point (perforations down).
Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed
3 inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be
densified by water jetting upon approval by geotechnical engineer.
Footing: If bench is created behind the tooting greater than the tooting width, use
level till or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
Native backfill: If E.I. (21 and S.E. )35 then all sand requirements also may not be required
and will be reviewed by the geotechnical consultant.
fQff' RETAINING WALL DETAIL - ALTERNATIVE C Detail 3
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c) Embed the footings entirely into native formational material (i.e., deepened
I footings).
If transitions from cut to fill transect the wall footing alignment at an angle of less than
I 45 degrees (plan view), then the designer should follow recommendation "a" (above) and
until such transition is between 45 and 90 degrees to the wall alignment.
TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS
Expansive Soils and Slope Creep
Some of the onsite soils may be expansive. Expansive soils become desiccated when
allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal
changes in moisture content. Typically in southern California, during the hot and dry
summer period, these soils become desiccated and shrink, thereby developing surface
cracks. The extent and depth of these shrinkage cracks depend on many factors such as
the nature and expansivity of the soils, temperature and humidity, and extraction of
moisture from surface soils by plants and roots. When seasonal rains occur, water
percolates into the cracks and fissures, causing slope surfaces to expand, with a
corresponding loss in soil density and shear strength near the slope surface. With the
passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials
experience a very slow, but progressive, outward and downward movement, known as
slope creep. For slope heights greater than 10 feet, this creep related soil movement will
typically impact all rear yard flatwork and other secondary improvements that are located
within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork,
etc., and in particular top of slope fencss/walls. This influence is normally in the form of
detrimental settlement, and tilting of the proposed improvements. The dessication/swelling
and creep discussed above continues over the life of the improvements, and generally
becomes progressively worse. Accordingly, the developer should provide this information
to all interested/affected parties.
Top of Slope Walls/Fences
Due to the potential for slope creep for slopes higher than about 10 feet, some settlement
and tilting of the walls/fence with the corresponding distress, should be expected. To
mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be
constructed on a combination of grade beam and caisson foundations. The grade beam
should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled
caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on
center, and with a minimum embedment length of 7 feet below the bottom of the grade
beam. The strength of the concrete and grout should be evaluated by the structural
engineer of record. The proper ASTM tests for the concrete and mortar should be
provided along with the slump quantities. The concrete used should be appropriate to
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mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons
I should be in accordance with the recommendations of the project structural engineer, and
include the utilization of the following geotechnical parameters:
Creep Zone: 5-foot vertical zone below the slope face and projected upward
parallel to the slope face.
I Creep Load: The creep load projected on the area of the grade beam
should be taken as an equivalent fluid approach, having a
density of 60 pcf. For the caisson, it should be taken as a
I uniform 900 pounds per linear foot of caisson's depth, located
above the creep zone.
I Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below
the creep zone.
I Passive Resistance: Passive earth pressure of 250 psf per foot of depth per foot of
caisson diameter, to a maximum value of 2,500 psf may be
I used to determine caisson 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 I resistance, should be disregarded.
I Allowable Axial Capacity:
Shaft capacity: 300 psf applied below the point of fixity over the surface
area of the shaft in approved compacted fill (mm. 90%
I relative compaction) or terrace deposits.
Tip capacity: 3,000 psf in approved compacted fill (mm. 90% relative
compaction) or terrace deposits.
1 EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS
I Some of the onsite soils may be expansive. The effects of expansive soils are cumulative,
and typically occur over the lifetime of any improvements. On relatively level areas, when
the soils are allowed to dry, the dessication and swelling process tends to cause heaving
I and distress to flatwork and other improvements. The resulting potential for distress to
improvements may be reduced, but not totally eliminated. To that end, it is recommended
that the developer should notify all interested/affected parties of this long-term potential for
I distress. To reduce the likelihood of distress, the following recommendations are
presented for all exterior flatwork:
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The subgrade area for concrete slabs should be compacted to achieve a minimum
I
90 percent relative compaction, and then be presoaked to 2 to 3 percentage points
above (or 125 percent of) the soils' optimum moisture content, to a depth of
18 inches below subgrade elevation. The moisture content of the subgrade should
I be proof tested within 72 hours prior to pouring concrete.
Concrete slabs should be cast over a relatively non-yielding surface, consisting of
I a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and
level prior to pouring concrete. The layer should wet-down completely prior to
pouring concrete, to minimize loss of concrete moisture to the surrounding earth
I materials. If subgrade soils are very low expansive, the gravel layer may be omitted.
Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and
I approaches should additionally have a thickened edge (8 inches) adjacent to all
landscape areas, to help impede infiltration of landscape water under the slab.
The use of transverse and longitudinal control joints are recommended to help
control slab cracking due to concrete shrinkage or expansion. Two ways to
mitigate such cracking are: a) add a sufficient amount of reinforcing steel,
I increasing tensile strength of the slab; and, b) provide an adequate amount of
control and/or expansion joints to accommodate anticipated concrete shrinkage
I and expansion.
In order to reduce the potential for unsightly cracks, slabs should be reinforced at
I mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each
direction. The exterior slabs should be scored or saw cut, ½ to /8 inches deep,
often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or
I narrow slabs, control joints should be provided at intervals of every 6 feet. The
slabs should be separated from the foundations and sidewalks with expansion joint
filler material.
No traffic should be allowed upon the newly poured concrete slabs until they have
been properly cured to within 75 percent of design strength. Concrete compression
strength should be a minimum of 2,500 psi.
Driveways, sidewalks, and patio slabs adjacent to the residential structures should
be separated from the residences with thick expansion joint filler material. In areas
directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.),
all joints should be additionally sealed with flexible mastic.
Planters and walls should not be tied to the residential structures.
I 8. Overhang structures should be supported on the slabs, or structurally designed
with continuous footings tied in at least two directions.
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9. Any masonry landscape walls that are to be constructed throughout the property
I should be grouted and articulated in segments no more than 20 feet long. These
segments should be keyed or doweled together.
Utilities should be enclosed within a closed utilidor (vault) or designed with flexible
connections to accommodate differential settlement and expansive soil conditions.
Positive site drainage should be maintained at all times. Finish grade on the lots
should provide a minimum of 1 to 2 percent fall to the street, as indicated herein.
It should be kept in mind that drainage reversals could occur, including
I post-construction settlement, if relatively flat yard drainage gradients are not
periodically maintained by the homeowner or homeowners association.
Due to expansive soils, air conditioning (A/C) units should be supported by slabs
that are incorporated into the building foundation or constructed on a rigid slab with
flexible couplings for plumbing and electrical lines. A/C waste water lines should
be drained to a suitable non-erosive outlet.
Shrinkage cracks could become excessive if proper finishing and curing practices
are not followed. Finishing and curing practices should be performed per the
Portland Cement Association Guidelines. Mix design should incorporate rate of
curing for climate and time of year, sulfate content of soils, corrosion potential of
soils, and fertilizers used on site.
PRELIMINARY PAVEMENT DESIGN/CONSTRUCTION
Structural Section
Traffic Indices (TI) were assumed to range from 4.5 to 5.0 for the subject traffic areas, and
should be reviewed by the project civil engineer for comment, and any revisions, as
necessary. An R-value of 20 was assumed for preliminary planning purposes in this study.
The recommended preliminary pavement sections for both asphaltic concrete (A.C.)
pavement over aggregate base (A.B.), and Portland concrete cement pavement (PCCP),
are provided in the following tables:
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APPROXIMATE TRAFFIC SUBGRADE A.C.
THICKNESS
A.B.
THICKNESS (3) TRAFFIC AREA INDEX' R-VALUE2 (INCHES) (INCHES)
Cul du Sac 4.5 20 4.0 (5) 4.0 (5)
Residential Street 5.0 20 4.0 (5) 6.0
(')The TI is an estimation based on the intended use. The TI should be review for comment by the project
civil engineer. Trash disposal areas, entry areas, fire vehicle access may require special design detailing.
Estimate, to be verified prior to grading.
Denotes Class 2 Aggregate Base R >78, SE >25).
Designs should follow City of Carlsbad guidelines for PCCP aprons in front of trash enclosures.
City minimum.
PORTLAND CONCRETE CEMENT PAVE
1.
MENTS (PCCP)
TRAFFIC CONCRETE PCCP TRAFFIC CONCRETE PCCP
AREAS TYPE THICKNESS AREAS TYPE
I
THICKNESS
(INCHES) (INCHES)
520-C-2500 6.0 520-C-2500 8.0
Light Vehicles Heavy Truck Traffic
560-C-3250 5.0 560-C-3250 7.0
NOTE: All PCCP is designed as un-reinforced and bearing directly on compacted subgrade. However, a 4-inch thick
leveling course of compacted aggregate base, or crushed rock may be considered to improve performance. All PCCP
should be properly detailed (jointing, etc.) per the industry standard. Pavements may be additionally reinforced with
#4 reinforcing bars, placed 12 inches on center, each way, for improved performance. Trash truck loading pads shall
be 8 inches per the City standard reinforced accordingly.
All pavement installation, including preparation and compaction of subgrade, compaction
of base material, and placement and rolling of asphaltic concrete, etc., shall be done in
accordance with the County guidelines, and under the observation and testing of the
project geotechnical engineer and/or the County.
I The recommended pavement sections are meant as minimums. If thinner or highly
variable pavement sections are constructed, increased maintenance and repair may be
I needed. The recommended pavement sections provided above are intended as a
minimum guideline. If thinner or highly variable pavement sections are constructed,
increased maintenance and repair could be expected. If the ADT (average daily traffic) or
I ADIT (average daily truck traffic) increases beyond that intended, as reflected by the TI
used for design, increased maintenance and repair could be required for the pavement
section. Consideration should be given to the increased potential for distress from overuse
I of paved street areas by heavy equipment and/or construction related heavy traffic
(e.g., concrete trucks, loaded supply trucks, etc.), particularly when the final section is not
in place (i.e., topcoat). Best management construction practices should be followed at all
times, especially during inclement weather.
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Pervious Pavements
Manufacturer's guidelines for paver installation should be strictly adhered to. GSI should
review such guidelines for comment, prior to construction. Pervious asphaltic concrete
I (A.C.) or Portland Cement Concrete (PCC) pavements should be reviewed for location and
anticipated vehicle loading. Use of the AC or PCC pavement sections for said porous
pavements should not use the sections herein without additional review and analysis by
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I PAVEMENT GRADING RECOMMENDATIONS
I
General
All section changes should be properly transitioned. If adverse conditions are encountered
during the preparation of subgrade materials, special construction methods may need to
be employed. A GSI representative should be present for the preparation of subgrade,
aggregate base, and asphaltic concrete.
I
Subgrade
Within street and parking areas, all surlicial deposits of loose soil material should be
I removed and recompacted as recommended. After the loose soils are removed, the
bottom is to be scarified to a depth of at least 6 inches, moisture conditioned as necessary
and compacted to 95 percent of the maximum laboratory density, as determined by I ASTM D 1557.
Deleterious material, excessively wet or dry pockets, concentrated zones of oversized rock I fragments, and any other unsuitable materials encountered during grading should be
removed. The compacted fill material should then be brought to the elevation of the
I proposed subgrade for the pavement. The subgrade should be proof-rolled in order to
promote a uniform firm and unyielding surface. All grading and fill placement should be
observed by the project geotechnical consultant.
I Aggregate Base
Compaction tests are required for the recommended aggregate base section. Minimum
relative compaction required will be 95 percent of the laboratory maximum density as
determined by ASTM D 1557. Base aggregate should be in accordance to the
"Greenbook" crushed aggregate base rock (minimum R-value=78).
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Paving
I Prime coat may be omitted if all of the following conditions are met:
The asphalt pavement layer is placed within two weeks of completion of aggregate
base and/or subbase course.
Traffic is not routed over completed base before paving
Construction is completed during the dry season of May through October.
The aggregate base is kept free of debris prior to placement of asphaltic concrete.
If construction is performed during the wet season of November through April, prime coat
may be omitted if no rain occurs between completion of the aggregate base course and
paving and the time between completion of aggregate base and paving is reduced to three
days, provided the aggregate base is free of loose soil or debris. Where prime coat has
been omitted and rain occurs, traffic is routed over the aggregate base course, or paving
is delayed, measures shall be taken to restore the aggregate base course, and subgrade
to conditions that will meet specifications as directed by the geotechnical consultant.
Drainage
Positive drainage should be provided for all surface water to drain towards the area swale,
curb and gutter, or to an approved drainage channel. Positive site drainage should be
maintained at all times. Water should not be allowed to pond or seep into the ground,
such as from behind unprotected curbs, both during and after grading. If planters or
landscaping are adjacent to paved areas, measures should be taken to minimize the
potential for water to enter the pavement section, such as thickened edges, enclosed
planters, etc. Also, best management construction practices should be strictly adhered to
at all times to minimize the potential for distress during construction and roadway
improvements.
PCC Cross Gutters
PCC cross gutters should be designed in accordance with San Diego Regional Standard
Drawing (SDRSD) G-12.
Additional Considerations
I To mitigate perched groundwater, consideration should be given to installation of
subgrade separators (cut-offs) between pavement subgrade and landscape areas,
although this is not a requirement from a geotechnical standpoint. Cut-offs, if used, should
I be 6 inches wide and at least 12 inches below the pavement subgrade contact or
12 inches below the crushed aggregate base rock, if utilized.
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ONSITE INFILTRATION-RUNOFF RETENTION SYSTEM
I General
I Should onsite infiltration-runoff retention systems (OIRRS) be planned for Best
Management Practices (BMP's) or Low Impact Development (LID) principles for the
project, some guidelines should/must be followed in the planning, design, and
I 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
I 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 of the designed system (which may
include gravel, sand, mulch/topsoil, 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 of the OIRRS, may require additional infiltration
testing. Locally, relatively impermeable formations include: terrace deposits, claystone,
siltstone, cemented sandstone, igneous and metamorphic bedrock, as well as expansive
fill soils.
Some of the methods which are utilized for onsite infiltration include percolation basins,
dry wells, bio-swale/bio-retention, permeable payers/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 (2007a).
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It is not good engineering practice to allow water to saturate soils, especially near
I slopes or improvements; however, the controlling agency/authority is now requiring
this for OIRRS purposes on many projects.
I . If infiltration is planned, infiltration system design should be based on actual
infiltration testing results/data, preferably utilizing double-ring infiltrometer testing
(ASTM D 3385) to determine the infiltration rate of the earth materials being
I contemplated for infiltration.
Wherever possible, infiltration systems should not be installed within ±50 feet of the I tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where
H equals the height of slope).
I • 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).
I • 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
I 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
extensive root systems). Over-watering landscape areas above, or adjacent to, the ' proposed OIRRS could adversely affect performance of the 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.
Seismic shaking may result in the formation of a seiche which could potential
overtop the banks of an OIRRS and result in down-gradient flooding and scour.
I . If subsurface infiltration galleries/chambers are proposed, the appropriate size,
depth interval, and ultimate placement of the detention/infiltration system should be
evaluated by the design engineer, and be of sufficient width/depth to achieve
I 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
I 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.
I . Infiltrations systems should not be installed within ±8 feet of building foundations
utility trenches, and walls, or a 1:1 (horizontal to vertical [h:v]) slope (down and
I away) from the bottom elements of these improvements. Alternatively, deepened
foundations and/or pile/pier supported improvements may be used.
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Infiltrations systems should not be installed adjacentto pavement and/or hardscape
I improvements. Alternatively, deepened/thickened edges and curbs and/or
impermeable liners may be utilized in areas adjoining the OIRRS.
I . As with any OIRRS, localized ponding and groundwater seepage should be
anticipated. The potential for seepage and/or perched groundwater to occur after
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site development should be disclosed to all interested/affected parties.
Installation of infiltrations systems should avoid expansive soils ([.1. ~!51) or soils
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with a relatively high plasticity index (P.1. > 20).
Infiltration systems should not be installed where the vertical separation of the
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groundwater level is less than ±10 feet from the base of the system.
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
I recommended in Allen, et al. (2011).
Infiltration systems should be designed using a suitable factor of safety (FOS) to
I account for uncertainties in the known infiltration rates (as generally required by the
controlling authorities), and reduction in performance overtime.
As with any OIRRS, proper care will need to 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 of the 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 of the 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.
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Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other
I 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
I 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
I into open-graded gravel backfill layers unless separated from overlying or adjoining
OIRRS by geotextiles and/or slurry backfill.
I • The use of OIRRS above existing utilities that might degrade/corrode with the
introduction of water/seepage should be avoided.
DEVELOPMENT CRITERIA
I Slope Deformation
Compacted fill slopes designed using customary factors of safety for gross or surlicial I stability and constructed in general accordance with the design specifications should be
expected to undergo some differential vertical heave or settlement in combination with
I differential lateral movement in the out-of-slope direction, after grading. This
post-construction movement occurs in two forms: slope creep, and lateral fill extension
(LIFE). Slope creep is caused by alternate wetting and drying of the fill soils which results
I in slow downslope movement. This type of movement is expected to occur throughout the
life of the slope, and is anticipated to potentially affect improvements or structures (e.g.,
separations and/or cracking), placed near the top-of-slope, up to a maximum distance of
I approximately 15 feet from the top-of-slope, depending on the slope height. This
movement generally results in rotation and differential settlement of improvements located
within the creep zone. LIFE occurs due to deep wetting from irrigation and rainfall on
I slopes comprised of expansive materials. Although some movement should be expected,
long-term movement from this source may be minimized, but not eliminated, by placing
the fill throughout the slope region, wet of the fill's optimum moisture content.
I It is generally not practical to attempt to eliminate the effects of either slope creep or LIFE.
Suitable mitigative measures to reduce the potential of lateral deformation typically include:
I setback of improvements from the slope faces (per the 2010 CBC), positive structural
separations (i.e., joints) between improvements, and stiffening and deepening of
foundations. Expansion joints in walls should be placed no greater than 20 feet on-center,
I and in accordance with the structural engineer's recommendations. All of these measures
are recommended for design of structures and improvements. The ramifications of the
above conditions, and recommendations for mitigation, should be provided to all
interested/affected parties.
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Slope Maintenance and Planting
Water has been shown to weaken the inherent strength of all earth materials. Slope
stability is significantly reduced by overly wet conditions. Positive surface drainage away
from slopes should be maintained and only the amount of irrigation necessary to sustain
plant life should be provided for planted slopes. Over-watering should be avoided as it
adversely affects site improvements, and causes perched groundwater conditions. Graded
slopes constructed utilizing onsite materials would be erosive. Eroded debris may be
minimized and surficial slope stability enhanced by establishing and maintaining a suitable
vegetation cover soon after construction. Compaction to the face of fill slopes would tend
to minimize short-term erosion until vegetation is established. Plants selected for
landscaping fills and fill slopes 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 of a sparse plant cover. Utilizing
plants other than those recommended above will increase the potential for perched water,
staining, mold, etc., to develop. A rodent control program to prevent burrowing should be
implemented. Irrigation of natural (ungraded) slope areas is generally not recommended.
These recommendations regarding plant type, irrigation practices, and rodent control
should be provided to all interested/affected parties. Over-steepening of slopes should be
avoided during building construction activities and landscaping.
Drainage
Adequate surface drainage is a very important factor in reducing the likelihood of adverse
performance of foundations, hardscape, and slopes. Surface drainage should be sufficient
to mitigate ponding of water anywhere on the property, and especially near structures and
tops of slopes. 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.
Drainage should not flow uncontrolled down any descending slope. Water should be
directed away from foundations and tops of slopes, and not allowed to pond and/or seep
into the ground. In general, site drainage should conform to Section 1804.3 of the
2010 CBC. Consideration should be given to avoiding construction of planters adjacent
to structures (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 structures 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.
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Erosion Control
Natural and fill slopes will be subject to surficial erosion during and after grading. Onsite
soils have a moderate to high erosion potential. Consideration should be given to
providing hay bales and siltfences forthe temporary control of surface waterfor such soils,
from a geotechnical viewpoint. Thus, properly designed site drainage is necessary in
reducing erosion damage to the planned improvements.
Landscape Maintenance
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
residential 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 of the
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. Graded slope
areas should be planted with drought resistant vegetation. 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.
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 residential 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
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permeabilities may not be precluded from occurring in the future due to site irrigation, poor
I 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.
I 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 of the site,
or trench backfilling after rough grading has been completed. This includes any grading,
utility trench and retaining wall backfills, flatwork, etc.
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 of the subgrade materials would be recommended
at that time. Footing trench spoil and any excess soils generated from utility trench
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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 of the 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 homeowners, etc., that may perform
such work.
Utility Trench Backfill
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.
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.
All trench excavations should conform to CAL-OSHA, state, and local safety codes.
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 of the
structural engineer.
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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 freestanding 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.).
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 developer or 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.
I OTHER DESIGN PROFESSIONALS/CONSULTANTS
The design civil engineer, structural engineer, post-tension designer, architect, landscape
I architect, wall designer, etc., should review the recommendations provided herein,
incorporate those recommendations into all their respective plans, and by explicit
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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.
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, that the proposed foundations and/or improvements
can tolerate the amount of differential settlement and/or expansion characteristics and
other design criteria specified herein.
PLAN REVIEW
I 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
I 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 of the 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.
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Inasmuch as our study is based upon our review and engineering analyses and laboratory
I 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
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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
I services for this portion of the project.
I
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
I Respectfully submitt \0AL G ,
GeoSoils, Inc. ?7i
1 ..(° No. 193
,
CeWied I
-- ErcinCCrir.g
I -
CocOi.
Robert G. Crisman OF Cp.\*O
Engineering Geologist,
OLG I
No lq4O onn '. i-rankIi
( Certified
Engineering Geologist C L134Orir19 GecIojt .-
F RBB/RGC/DWS/JPF/Jh
Geotechnical Engineer, GE 2320
Attachments: Plate 1 - Proposed :Development
Appendix A - References
Appendix B - Seismicity Data
Appendix C - General Earthwork, Grading Guidelines, and Preliminary
Criteria
Distribution: (1) Addressee
(2) Masson and Associates, Inc., Attn: Mr. Bruce Tait (Wet signed)
(1) 4Design Architecture, Attn: Mr. Ken Chriss (via email)
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f.l ~ C !J'I! I ci: t!! I !~a ,;,:! a. t 11, ' MO..O t I-co 'ii ! 1= co > ::, G) al O C•j ~ a , ! • 3i : t...~r I i , ; 21 ii ' ! ~~ v I ! j• : Ii. ,: H ~ ~ BI ! i(. q H q ;1 I g. I
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i ! \; ~ .. ! ! ! D ·•i,
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I APPENDIX A
I REFERENCES
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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 I retarders used in contact with soil or granular fill under concrete slabs.
I , 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: F 1745-97 (Re-approved
2004).
Blake, Thomas F., 2000a, EQFAULT, A computer program for the estimation of peak
horizontal acceleration from 3-D fault sources; Windows 95/98 version.
2000b, EQSEARCH, A computer program for the estimation of peak horizontal
acceleration from California historical earthquake catalogs; Updated to December
2012, Windows 95/98 version.
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.
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California Department of Transportation, 2010, Caltrans, Standard specifications, May
printing.
Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and willis, C.J., 2003, The revised 2002
California probalistic seismic hazard maps, dated June,
http://www.conversation.ca.gov/cqs/rqhm/psha/fault parameters/pdf/documents
/2002 ca hazardmaps.pdf
Carlsbad, City of, 1993, Standards for design and construction of public works
improvements in the City of Carlsbad.
County of San Diego, Department of Planning and Land Use, 2007, Low impact
development (LID) handbook, stormwater management strategies,
dated December 31.
GeoSoils, Inc., 2005, Geotechnical grading plan review, Trails End Development,
northwest corner of the intersection of Donna Drive and Carlsbad Village Drive,
Carlsbad, San Diego County, California, W.O. 3993-Al-SC, dated August 29.
2003, Preliminary geotechnical evaluation, Trails End Development, Northwest
corner of the intersection of Donna Drive and Carlsbad Village Drive, City of
Carlsbad, San Diego County, W.O. 3993-A-SC, dated December 15.
International Conference of Building Officials,l 998, 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.
Masson and Associates, Inc., 2013, Precise grading plans for: Trails End Development,
Sheet 2 of 3, 20-scale, plot dated October 2.
State of California, 2013, Civil Code, Title 7, Division 2, Section 895, et seq.
State of California, Department of Transportation, 2012, Highway design manual of
instructions, dated May 7.
United States Geological Survey, 2013, U.S. Seismic design maps, earthquake hazards
program, http://qeohazards.usqs.qov/designmaps/us/application.php. Version
3.1.0, dated July.
2012, 2008 Earthquake Hazards Program, 2008 interactive deaggregations (Beta),
Earthquake Hazards Program; http://egint.cr.usqs.gov/deaqqint/2008/.
Donna Drive, LLC Appendix A
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I APPENDIX B
I SEISMICITY DATA
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* * * * * * * * * * * * * * * * * * * * * * *
* E Q F A U L T *
* *
* Version 3.00 *
* *
DETERMINISTIC ESTIMATION OF
PEAK ACCELERATION FROM DIGITIZED FAULTS
JOB NUMBER: 6635-A-SC
DATE: 11-19-2013
JOB NAME: DONNA DRIVE, LLC
CALCULATION NAME: 6635
FAULT-DATA-FILE NAME: C:\Program Files\EQFAULT1\CGSFLTE.DAT
SITE COORDINATES:
SITE LATITUDE: 33.1720
SITE LONGITUDE: 117.3307
SEARCH RADIUS: 62.14 mi
ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor.
UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0
DISTANCE MEASURE: cdist
SCOND: 1
Basement Depth: .00 km Campbell SSR: 0 Campbell SHR: 0
COMPUTE PEAK HORIZONTAL ACCELERATION
FAULT-DATA FILE USED: C:\Program Files\EQFAULT1\CGSFLTE.DAT
MINIMUM DEPTH VALUE (km): 3.0
Page 1
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EQFAULT SUMMARY ---------------
I -----------------------------
DETERMINISTIC SITE PARAMETERS
I Page 1
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I IESTIMATED MAX. EARTHQUAKE EVENT
I APPROXIMATE I ------------------------------- ABBREVIATED I DISTANCE I MAXIMUM I PEAK lEST. SITE
FAULT NAME I mi (km) IEARTHQUAKEI SITE JINTENSITY
NEWPORT-INGLEWOOD (Offshore) I 6.1( 9.8)1 7.1 I 0.552 I x
ROSE CANYON I 6.6( 10.6)1 7.2 I 0.549 I x
CORONADO BANK I 22.2( 35.8)1 7.6 I 0.260 I IX
ELSINORE (TEMECULA) I 23.0( 37.0)1 6.8 I 0.147 I VIII
ELSINORE (JULIAN) I 23.3( 37.5)1 7.1 I 0.177 I VIII
ELSINORE (GLEN IVY) I 32.6( 52.5)1 6.8 I 0.102 I VII
SAN JOAQUIN HILLS I 34.9( 56.2)1 6.6 I 0.119 I VII
PALOS VERDES I 36.1( 58.1)1 7.3 I 0.130 I VIII
EARTHQUAKE VALLEY I 43.4( 69.8)1 6.5 I 0.062 I VI
SAN JACINTO-ANZA I 45.5( 73.3)1 7.2 1 0.095 I VII
NEWPORT-INGLEWOOD (L.A.Basin) I 45.6( 73.4)1 7.1 I 0.089 I VII
SAN JACINTO-SAN JACINTO VALLEY I 46.0( 74.0)1 6.9 I 0.077 I VII
CHINO-CENTRAL AVE. (Elsinore) I 46.9( 75.4)1 6.7 I 0.092 I VII
WHITTIER I 50.8( 81.7)1 6.8 I 0.064 I VI
SAN JACINTO-COYOTE CREEK I 51.5( 82.9)1 6.6 I 0.055 I VI
ELSINORE (COYOTE MOUNTAIN) I 57.8( 93.1)1 6.8 I 0.056 I VI
SAN JACINTO-SAN BERNARDINO I 58.7( 94.4)1 6.7 I 0.052 I VI
PUENTE HILLS BLIND THRUST I 60.8( 97.8)1 7.1 I 0.093 I VII *
-END OF SEARCH- 18 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS.
THE NEWPORT-INGLEWOOD (Offshore) FAULT IS CLOSEST TO THE SITE.
IT IS ABOUT 6.1 MILES (9.8 km) AWAY.
LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.5524 g
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PLATE B-2
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T!IC
CALIFORNIA FAULT MAP
DONNA DRIVE, LLC
W.O. 6635-A-SC
PLATE B-3
MAXIMUM EARTHQUAKES
DONNA DRIVE, LLC
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C 0
1.
C.)
C.)
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1 10 100
Distance (mi)
W.O. 6635-A-SC
PLATE B-4
* * * * * * * * * *k * * * * * * * * *
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* Version 3.00 *
ESTIMATION OF
PEAK ACCELERATION FROM
CALIFORNIA EARTHQUAKE CATALOGS
JOB NUMBER: 6635-A-SC
DATE: 11-19-2013
JOB NAME: DONNA DRIVE, LLC
EARTHQUAKE-CATALOG-FILE NAME: ALLQUAKE.DAT
SITE COORDINATES:
SITE LATITUDE: 33.1720
SITE LONGITUDE: 117.3307
SEARCH DATES:
START DATE: 1800
END DATE: 2012
SEARCH RADIUS:
62.1 mi
100.0 km
ATTENUATION RELATION: 11) Bozorgrlia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor.
UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0
ASSUMED SOURCE TYPE: SS [SS=Strike-slip, DS=Reverse-slip, BT=Blind-thrust]
SCOND: 1 Depth Source: A
Basement Depth: .00 km Campbell SSR: 0 Campbell SHR: 0
COMPUTE PEAK HORIZONTAL ACCELERATION
MINIMUM DEPTH VALUE (km): 3.0
Page 1
W.O. 6635-A-SC
PLATE B-S
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EARTHQUAKE SEARCH RESULTS -------------------------
Page 1
I I I TIME I I I SITE ISITEI APPROX.
FILEI LAT. I LONG. I DATE I (uTc) IDEPTHIQUAKEI ACC. I MM I DISTANCE
CODEI NORTH I WEST I I H M Secl (km)l MAG.I g IINT.I mi [km] ----+-------+--------+----------+--------+-----+-----+-------+----+------------
0MG 33.00001117.3000111/22/180012130 0.01 0.01 6.501 0.230 I IX I 12.0( 19.3)
MGI I33.00001117.0000109/21/18561 730 0.01 0.01 5.001 0.049 I VI I 22.5( 36.2)
MGI I32.80001117.1000105/25/18031 0 0 0.01 0.01 5.001 0.038 I V I 28.9( 46.6)
DMG 132.70001117.2000105/27/1862120 0 0.01 0.01 5.901 0.055 I VI I 33.5( 53.8)
PAS 132.97101117.8700107/13/198611347 8.21 6.01 5.301 0.038 1 V I 34.1( 54.9)
T-A I32.67001117.1700112/OO/18561 0 0 0.01 0.01 5.001 0.030 I V I 35.9( 57.7)
T-A I32.67001117.1700110/21/18621 0 0 0.01 0.01 5.001 0.030 I V I 35.9( 57.7)
T-A 132.67001117.1700105/24/18651 0 0 0.01 0.01 5.001 0.030 I V I 35.9( 57.7)
DMG I33.20001116.7000101/01/19201 235 0.01 0.01 5.001 0.030 I V I 36.5( 58.7)
DMG I33.70001117.4000105/13/19101 620 0.01 0.01 5.001 0.029 I V I 36.7( 59.0)
DMG I33.70001117.4000105/15/191011547 0.01 0.01 6.001 0.054 I VI I 36.7( 59.0)
DMG I33.70001117.4000104/11/19101 757 0.01 0.01 5.001 0.029 I V I 36.7( 59.0)
DMG I33.69901117.5110105/31/19381 83455.41 10.01 5.501 0.038 I V I 37.8( 60.9)
DMG I32.80001116.8000110/23/1894123 3 0.01 0.01 5.701 0.041 I V I 40.1( 64.5)
MGI I33.20001116.6000110/12/192011748 0.01 0.01 5.301 0.030 I V I 42.3( 68.0)
DMG I33.71001116.9250109/23/19631144152.61 16.51 5.001 0.024 I V I 43.9( 70.6)
DMG I33.75001117.0000104/21/19181223225.01 0.01 6.801 0.075 I VIII 44.2( 71.2)
DMG I33.75001117.0000106/06/191812232 0.01 0.01 5.001 0.024 I V I 44.2( 71.2)
MGI I33.80001117.6000104/22/191812115 0.01 0.01 5.001 0.023 I IV I 46.0( 74.1)
DMG I33.57501117.9830103/11/19331 518 4.01 0.01 5.201 0.026 I V I 46.8( 75.3)
DMG I33.80001117.0000112/25/189911225 0.01 0.01 6.401 0.053 I VI I 47.4( 76.2)
DMG 133.61701117.9670103/11/19331 154 7.81 0.01 6.301 0.049 I VI I 47.8( 77.0)
DMG I33.61701118.0170103/14/1933119 150.01 0.01 5.101 0.022 I IV I 50.1( 80.6)
GSP I33.52901116..5720106/12/20051154146.5I 14.01 5.201 0.024 I IV I 50.2( 80.8)
DMG I33.90001117.2000112/19/18801 0 0 0.01 0.01 6.001 0.038 I V I 50.8( 81.8)
GSG I33.42001116.4890107/07/20101235333.51 14.01 5.501 0.028 I V I 51.5( 82.9)
PAS I33.50101116.5130102/25/19801104738.51 13.61 5.501 0.027 I V I 52.3( 84.2)
GSP I33.50801116.5140110/31/20011075616.61 15.01 5.101 0.021 I IV I 52.5( 84.5)
DMG I33.50001116.5000109/30/19161 211 0.01 0.01 5.001 0.020 I IV I 53.0( 85.3)
DMG I33.00001116.4330106/04/194011035 8.31 0.01 5.101 0.021 I IV I 53.3( 85.7)
DMG I33.68301118.0500103/11/19331 658 3.01 0.01 5.501 0.026 I V I 54.4( 87.6)
DMG I33.70001118.0670103/11/19331 51022.01 0.01 5.101 0.020 I IV I 55.9( 90.0)
DMG I33.70001118.0670103/11/19331 85457.01 0.01 5.101 0.020 I IV I 55.9( 90.0)
DMG I34.00001117.2500107/23/19231 73026.01 0.01 6.251 0.039 I V I 57.4( 92.3)
MGI I34.00001117.5000112/16/1858110 0 0.01 0.01 7.001 0.064 I VI I 58.0( 93.3)
DMG I33.34301116.3460104/28/19691232042.91 20.01 5.801 0.029 I V I 58.1( 93.4)
DMG I33.75001118.0830103/11/19331 230 0.01 0.01 5.101 0.019 I IV I 58.9( 94.8)
DMG I33.75001118.0830103/11/19331 323 0.01 0.01 5.001 0.018 I IV I 58.9( 94.8)
DMG I33.75001118.0830103/11/19331 910 0.01 0.01 5.101 0.019 I IV I 58.9( 94.8)
DMG I33.75001118.0830103/13/19331131828.OI 0.01 5.301 0.021 I IV I 58.9( 94.8)
DMG I33.75001118.0830103/11/19331 2 9 0.01 0.01 5.001 0.018 I IV I 58.9( 94.8)
GSG I33.95301117.7610107/29/20081184215.71 14.01 5.301 0.021 I IV I 59.3( 95.5)
DMG I33.95001116.8500109/28/19461 719 9.01 0.01 5.001 0.017 I IV I 60.4( 97.2)
DMG I33.40001116.3000102/09/1890112 6 0.01 0.01 6.301 0.038 I V I 61.5( 99.0)
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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PLATE B-6
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-END OF SEARCH- 44 EARTHQUAKES FOUND WITHIN THE SPECIFIED SEARCH AREA.
TIME PERIOD OF SEARCH: 1800 TO 2012
LENGTH OF SEARCH TIME: 213 years
THE EARTHQUAKE CLOSEST TO THE SITE IS ABOUT 12.0 MILES (19.3 km) AWAY.
LARGEST EARTHQUAKE MAGNITUDE FOUND IN THE SEARCH RADIUS: 7.0
LARGEST EARTHQUAKE SITE ACCELERATION FROM THIS SEARCH: 0.230 g
COEFFICIENTS FOR GUTENBERG & RICHTER RECURRENCE RELATION:
a-value= 0.907
b-value= 0.364
beta-value= 0.837
------------------------------------
TABLE OF MAGNITUDES AND EXCEEDANCES:
Earthquake I Number of Times I Cumulative
Magnitude I Exceeded I No. / Year +-----------------+------------
4.0 I 44 I 0.20755
4.5 I 44 I 0.20755
5.0 I 44 I 0.20755
5.5 I 16 I 0.07547
6.0 I 9 I 0.04245
6.5 I 3 I 0.01415
7.0 I 1 I 0.00472
Page 3
W.O. 6635-A-SC
PLATE B-7
100
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—100
—400 -300 —200 —100 0 100 200 300 400 500 600
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EARTHQUAKE EPICENTER MAP
DONNA DRIVE, LLC
W.O. 6635—A—SC
PLATE B-8
W.O. 6635-A-SC
PLATE B-9
100
10
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ss· -1 m -a u 'E
~ > '
~. "" -~/'-
DONNA_DRIVE,_LL Geographic Deagg. Seismic H
for 0.00-s Spectral Accel, 0.2640 g
PGA Exceedance Return Time: 475 year
Max. significant source distance 129. km.
View angle is 35 degrees above horizon
Gridded-source hazard accum. in 45° intervals
Soil site. Vs30(m/s):f= 30
~
~ 0 .--~· ~ Il l A..,.'-II ci llllll I )
8 --c:,
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7.7
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7.1 M 6.8
6.5 6.2
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2013 Nov 19 19:09:12 SIIICoonfl:,117.33033.mD(yelowdilll)V.»r 300..0. Mn 1mUII EllcdRllll .2408EAl3(cotu11111 IMiglll prop. llCI EJIR*). Redcilmondl: lllatoricll ........ , M>6
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~ "
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~
c,~ o>o >median ~~ ~
O<eo <0.5 -"""~ <S>o
<medlan(R,M)
• £o<-2
• -2 < £o<-l
u -1 < Eo <-0.5
• -0.5 <£0 <O •
0.5 < Eo < 1
I <eo<2
2 <ea< 3 200910 UPDATE
PSH Deaggregation on NEHRP D soil
DONNA DRIVE, LL 117.331° W, 33.172 N.
Peak Horiz.-Ground Accel.>=0.2641 g
Ann. Exceedance Rate .21 lE-02. Mean Return Time 475 years
Mean (R,M,£0) 27.3 km, 6.65, 0.65
Modal (R,M,£o) = 12.0 km, 6.61 , 0.19 (from peak R,M bin)
Modal (R,M,e*) = 11.2 km, 6.77, 0 to 1 sigma (from peak R,M,e bin)
Binning: DeltaR 10. km, deltaM=0.2, Deltae= 1.0
~' ,qp
liJffl 2013 Nov 19 19:09: 12 Distance (R). magnffude (M), apalon (ED.El duggregation for a allll on 90D with awrage _.. 300. mis lop 30 m. USOS CGHT PSHA2008 UPOA TE Bins with It 0.09'llo contrib. omitlad
~
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~-.--
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3'1' -I "
i ~ .:::.
'#. 0 N
)
'.;I
'a (.) (I)
33' 1 ti 3 'i:
Cl >
!l
-·
DONNA_DRJVE,_LL Geographic Deagg. Seismic H
for 0.00-s Spectral Accel, 0.4687 g
PGA Exceedance Return Time: 2475 year
Max. significant source distance 109. km.
View angle is 35 degrees above horizon
Gridded-source hazard accum. in 45° intervals
Soil site. Vs30(m/sm= 300.0
11 ~
~ 11 I ., _____ ,
·,
.4
8.1
7.8
7.5
7.2 M 6.9
6.6
6.3
6.0
5.7
• ~--------. ~
11 --~~ ~ . -....-:
il>, g
s· ~,~ c:i
OB D ~ ,8 ~
a B~
El
t:j -"'9 GI D 8 -/ r,. ...... ...._ I D . -D ~
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0 :10 .. 0 , eo
km •
~ q
t-34•
t-33•
2013 Nov 1919:06:53 I S.COOfda:,117.33033.1120 (Yellawchll)Va30s300.0. Maunnu81 Eia:dlblle.AI037E~(cotumn height prop. to EzRale). Red clalnoftla: hllloric;al Ml"llqum!s, M>a
~
0 "U . r m )> 0) -l (,.) mCf
OJ ~ :.,. (/)
(,.) 0
~ "'
~
i ~ :t: I.() ~
~ ~ ~ 8 't u
*
~
G>
Prob. SA, PGA
<medlan(R,M)
I eo<-2
I -2<eo<-t
I -1 < eo <-0.5
I -0.5 <e0 <O
.....-c::> ~
>median , ... ~·
L O<eo<O~~~· . ~ 0.5 < Eo < 1
Ci I <e0 <2
• 2 <e0 <3 200910 UPDATE
PSH Deaggregation on NEHRP D soil
DONNA DRIVE, LL 117.331°W,33.172N.
Peak Horiz.Ground Accel.>=0.4687 g
Ann. Exceedance Rate .400E-03. Mean Return Time 2475 years
Mean (R,M,Eo) 16. 7 km, 6.64, 1.08
Modal (R,M,Eo) = 11.6 km, 6.62, 1.11 (from peak R,M bin)
Modal (R,M,e*) = 11.5 km, 6.63, l to 2 sigma (from peak R,M,£ bin)
Binning: DeltaR 10. km, deltaM=0.2, Delta£= 1.0
ffll'ilJ 2013 Nov 19 19:06 :53 • Distance (R), m11gnltu~ (M), epsilon (EO,E) daaggrt!Qation for a aitlt on aoll with aw,rage YP 300. mll lDp 30 m. USGS CGHT PSHA2008 UPDATE Bina With It OJ)5% contrib. otnlllllld
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I APPENDIX C
I GENERAL EARTHWORK, GRADING GUIDELINES
AND PRELIMINARY CRITERIA
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I General
GENERAL EARTHWORK AND GRADING GUIDELINES
These guidelines present general procedures and requirements for earthwork and grading
as shown on the approved grading plans, including preparation of areas to be filled,
placement of fill, installation of subdrains, excavations, and appurtenant structures or
flatwork. The recommendations contained in the geotechnical report are part of these
earthwork and grading guidelines and would supercede the provisions contained hereafter
in the case of conflict. Evaluations performed by the consultant during the course of
grading may result in new or revised recommendations which could supercede these
guidelines or the recommendations contained in the geotechnical report. Generalized
details follow this text.
The contractor is responsible for the satisfactory completion of all earthwork in accordance
with provisions of the project plans and specifications and latest adopted code. In the case
of conflict, the most onerous provisions shall prevail. The project geotechnical engineer
and engineering geologist (geotechnical consultant), and/or their representatives, should
provide observation and testing services, and geotechnical consultation during the
duration of the project.
EARTHWORK OBSERVATIONS AND TESTING
Geotechnical Consultant
Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer
and engineering geologist) should be employed for the purpose of observing earthwork
procedures and testing the fills for general conformance with the recommendations of the
geotechnical report(s), the approved grading plans, and applicable grading codes and
ordinances.
The geotechnical consultant should provide testing and observation so that an evaluation
I may be made that the work is being accomplished as specified. It is the responsibility of
the contractor to assist the consultants and keep them apprised of anticipated work
schedules and changes, so that they may schedule their personnel accordingly.
I All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and
subdrain installation should be observed and documented by the geotechnical consultant
I prior to placing any fill. It is the contractor's responsibility to notify the geotechnical
consultant when such areas are ready for observation.
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Laboratory and Field Tests
Maximum dry density tests to determine the degree of compaction should be performed
in accordance with American Standard Testing Materials test method ASTM designation
D-1557. Random or representative field compaction tests should be performed in
accordance with test methods ASTM designation D-1 556, D-2937 or D-2922, and D-3017,
at intervals of approximately ±2 feet of fill height or approximately every 1,000 cubic yards
placed. These criteria would vary depending on the soil conditions and the size of the
project. The location and frequency of testing would be at the discretion of the
geotechnical consultant.
Contractor's Responsibility
All clearing, site preparation, and earthwork performed on the project should be conducted
by the contractor, with observation by a geotechnical consultant, and staged approval by
the governing agencies, as applicable. It is the contractor's responsibility to prepare the
ground surface to receive the fill, to the satisfaction of the geotechnical consultant, and to
place, spread, moisture condition, mix, and compact the fill in accordance with the
recommendations of the geotechnical consultant. The contractor should also remove all
non-earth material considered unsatisfactory by the geotechnical consultant.
Notwithstanding the services provided by the geotechnical consultant, it is the sole I responsibility of the contractor to provide adequate equipment and methods to accomplish
the earthwork in strict accordance with applicable grading guidelines, latest adopted codes
I or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient
watering apparatus and compaction equipment should be provided by the contractor with
due consideration for the fill material, rate of placement, and climatic conditions. If, in the
I opinion of the geotechnical consultant, unsatisfactory conditions such as questionable
weather, excessive oversized rock or deleterious material, insufficient support equipment,
etc., are resulting in a quality of work that is not acceptable, the consultant will inform the
I contractor, and the contractor is expected to rectify the conditions, and if necessary, stop
work until conditions are satisfactory.
During construction, the contractor shall properly grade all surfaces to maintain good
drainage and prevent ponding of water. The contractor shall take remedial measures to
control surface water and to prevent erosion of graded areas until such time as permanent
drainage and erosion control measures have been installed.
SITE PREPARATION
All major vegetation, including brush, trees, thick grasses, organic debris, and other
I deleterious material, should be removed and disposed of off-site. These removals must
be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock
materials, as evaluated by the geotechnical consultant as being unsuitable, should be
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removed prior to any fill placement. Depending upon the soil conditions, these materials
I may be reused as compacted fills. Any materials incorporated as part of the compacted
fills should be approved by the geotechnical consultant.
I Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic
tanks, wells, pipelines, or other structures not located prior to grading, are to be removed
or treated in a manner recommended by the geotechnical consultant. Soft, dry, spongy,
highly fractured, or otherwise unsuitable ground, extending to such a depth that surface
processing cannot adequately improve the condition, should be overexcavated down to
firm ground and approved by the geotechnical consultant before compaction and filling
operations continue. Overexcavated and processed soils, which have been properly
mixed and moisture conditioned, should be re-compacted to the minimum relative
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compaction as specified in these guidelines.
Existing ground, which is determined to be satisfactory for support of the fills, should be
scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical
consultant. After the scarified ground is brought to optimum moisture content, or greater
and mixed, the materials should be compacted as specified herein. If the scarified zone
is greater than 6 to 8 inches in depth, it may be necessary to remove the excess and place I the material in lifts restricted to about 6 to 8 inches in compacted thickness.
Existing ground which is not satisfactory to support compacted fill should be I overexcavated as required in the geotechnical report, or by the on-site geotechnical
consultant. Scarification, disc harrowing, or other acceptable forms of mixing should
I continue until the soils are broken down and free of large lumps or clods, until the working
surface is reasonably uniform and free from ruts, hollows, hummocks, mounds, or other
uneven features, whichwould inhibit compaction as described previously.
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical
[h:v]), the ground should be stepped or benched. The lowest bench, which will act as a
key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm
material, and approved by the geotechnical consultant. In fill-over-cut slope conditions,
the recommended minimum width of the lowest bench or key is also 15 feet, with the key
founded on firm material, as designated by the geotechnical consultant. As a general rule,
unless specifically recommended otherwise by the geotechnical consultant, the minimum
width of fill keys should be equal to 1/2 the height of the slope.
Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable
material. Benching may be used to remove unsuitable materials, although it is understood
that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered
for unsuitable materials in excess of 4 feet in thickness.
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All areas to receive fill, including processed areas, removal areas, and the toes of fill
I benches, should be observed and approved by the geotechnical consultant prior to
placement of fill. Fills may then be properly placed and compacted until design grades
(elevations) are attained.
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COMPACTED FILLS
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Fill materials derived from benching operations should be dispersed throughout the fill
area and blended with other approved material. Benching operations should not result in
the benched material being placed only within a single equipment width away from the
fill/bedrock contact.
Oversized materials defined as rock, or other irreducible materials, with a maximum
dimension greater than 12 inches, should not be buried or placed in fills unless the
location of materials and disposal methods are specifically approved by the geotechnical
consultant. Oversized material should be taken offsite, or placed in accordance with
recommendations of the geotechnical consultant in areas designated as suitable for rock
disposal. GSI anticipates that soils to be utilized as fill material for the subject project may
contain some rock. Appropriately, the need for rock disposal may be necessary during
grading operations on the site. From a geotecl-nical standpoint, the depth of any rocks,
rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is
generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and
generally facilitates the excavation of structural fcotings and substructures. Should deeper
excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas,
etc.), the developer may consider increasing the hold-down depth of any rocky fills to be
placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific
hold-down depth for oversize materials placed ir fills. The hold-down depth, and potential
to encounter oversize rock, both within fills, and occurring in cut or natural areas, would
need to be disclosed to all interested/affected parties. Once approved by the governing
agency, the hold-down depth for oversized rock (i.e., greater than 12 inches) in fills on this
project is provided as 10 feet, unless specified differently in the text of this report. The
governing agency may require that these materials need to be deeper, crushed, or
reduced to less than 12 inches in maximum dimension, at their discretion.
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Any earth materials imported or excavated on the property may be utilized in the fill
provided that each material has been evaluated to be suitable by the geotechnical
consultant. These materials should be free of roots, tree branches, other organic matter,
or other deleterious materials. All unsuitable materials should be removed from the fill as
directed by the geotechnical consultant. Soils cf poor gradation, undesirable expansion
potential, or substandard strength characteristics may be designated by the consultant as
unsuitable and may require blending with other soils to serve as a satisfactory fill material.
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To facilitate future trenching, rock (or oversized material), should not be placed within the
I hold-down depth feet from finish grade, the range of foundation excavations, future utilities,
or underground construction unless specifically approved by the governing agency, the
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geotechnical consultant, and/or the developer's representative.
If import material is required for grading, representative samples of the materials to be
utilized as compacted fill should be analyzed in the laboratory by the geotechnical
consultant to evaluate it's physical properties and suitability for use onsite. Such testing
should be performed three (3) days prior to importation. If any material other than that
previously tested is encountered during grading, an appropriate analysis of this material
I should be conducted by the geotechnical consultant as soon as possible.
Approved fill material should be placed in areas prepared to receive fill in near horizontal
layers, that when compacted, should not exceed about 6 to 8 inches in thickness. The
geotechnical consultant may approve thick lifts if testing indicates the grading procedures
are such that adequate compaction is being achieved with lifts of greater thickness. Each
layer should be spread evenly and blended to attain uniformity of material and moisture
suitable for compaction.
Fill layers at a moisture content less than optimum should be watered and mixed, and wet
fill layers should be aerated by scarification, or should be blended with drier material.
Moisture conditioning, blending, and mixing of the fill layer should continue until the fill
materials have a uniform moisture content at, or above, optimum moisture.
After each layer has been evenly spread, moisture conditioned, and mixed, it should be
uniformly compacted to a minimum of 90 percent of the maximum density as evaluated by
ASTM test designation D-1 557, or as otherwise recommended by the geotechnical
consultant. Compaction equipment should be adequately sized and should be specifically
designed for soil compaction, or of proven reliability to efficiently achieve the specified
degree of compaction.
Where tests indicate that the density of any layer of fill, or portion thereof, is below the
required relative compaction, or improper moisture is in evidence, the particular layer or
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portion shall be re-worked until the required density and/or moisture content has been
attained. No additional fill shall be placed in an area until the last placed lift of fill has been
tested and found to meet the density and moisture requirements, and is approved by the
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geotechnical consultant.
In general, per the latest adopted version of the California Building Code (CBC), fill slopes
I should be designed and constructed at a gradient of 2:1 (h:v), or flatter. Compaction of
slopes should be accomplished by over-building a minimum of 3 feet horizontally, and
subsequently trimming back to the design slope configuration. Testing shall be performed
I as the fill is elevated to evaluate compaction as the fill core is being developed. Special
efforts may be necessary to attain the specified compaction in the fill slope zone. Final
slope shaping should be performed by trimming and removing loose materials with
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appropriate equipment. A final evaluation of fill slope compaction should be based on
observation and/or testing of the finished slope face. Where compacted fill slopes are
designed steeper than 2:1 (h:v), prior approval from the governing agency, specific
material types, a higher minimum relative compaction, special reinforcement, and special
grading procedures will be recommended.
If an alternative to over-building and cuffing back the compacted fill slopes is selected,
I then special effort should be made to achieve the required compaction in the outer 10 feet
of each lift of fill by undertaking the following:
An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot
should be used to roll (horizontal) parallel to the slopes continuously as fill is
placed. The sheepsfoot roller should also be used to roll perpendicular to the
slopes, and extend out over the slope to provide adequate compaction to the face
of the slope.
Loose fill should not be spilled out over the face of the slope as each lift is
compacted. Any loose fill spilled over a previously completed slope face should be
trimmed off or be subject to re-rolling.
1. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the
slope at appropriate vertical intervals, subsequent to compaction operations.
After completion of the slope, the slope face should be shaped with a small tractor
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and then re-rolled with a sheepsfoot to achieve compaction to near the slope face.
Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to
achieve compaction to the slope face. Final testing should be used to evaluate
compaction after grid rolling.
Where testing indicates less than adequate compaction, the contractor will be
responsible to rip, water, mix, and recompact the slope material as necessary to
achieve compaction. Additional testing should be performed to evaluate
compaction.
SUBDRAIN INSTALLATION
I Subdrains should be installed in approved ground in accordance with the approximate
alignment and details indicated by the geotechnical consultant. Subdrain locations or
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materials should not be changed or modified without approval of the geotechnical
consultant. The geotechnical consultant may recommend and direct changes in subdrain
line, grade, and drain material in the field, pending exposed conditions. The location of
I constructed subdrains, especially the outlets, should be recorded/surveyed by the project
civil engineer. Drainage at the subdrain outlets should be provided by the project civil
engineer.
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EXCAVATIONS
Excavations and cut slopes should be examined during grading by the geotechnical
consultant. If directed by the geotechnical consultant, further excavations or
overexcavation and refilling of cut areas should be performed, and/or remedial grading of
cut slopes should be performed. When fill-over-cut slopes are to be graded, unless
otherwise approved, the cut portion of the slope should be observed by the geotechnical
consultant prior to placement of materials for construction of the fill portion of the slope.
The geotechnical consultant should observe all cut slopes, and should be notified by the
contractor when excavation of cut slopes commence.
If, during the course of grading, unforeseen adverse or potentially adverse geologic
conditions are encountered, the geotechnical consultant should investigate, evaluate, and
make appropriate recommendations for mitigation of these conditions. The need for cut
slope buttressing or stabilizing should be based on in-grading evaluation by the
geotechnical consultant, whether anticipated or not.
Unless otherwise specified in geotechnical and geological report(s), no cut slopes should
be excavated higher or steeper than that allowed by the ordinances of controlling
governmental agencies. Additionally, short-term stability of temporary cut slopes is the
contractor's responsibility.
Erosion control and drainage devices should be designed by the project civil engineer and
should be constructed in compliance with the ordinances of the controlling governmental
agencies, and/or in accordance with the recommendations of the geotechnical consultant.
COMPLETION
Observation, testing, and consultation by the geotechnical consultant should be
conducted during the grading operations in order to state an opinion that all cut and fill
areas are graded in accordance with the approved project specifications. After completion
of grading, and after the geotechnical consultant has finished observations of the work,
final reports should be submitted, and may be subject to review by the controlling
governmental agencies. No further excavation orfilling should be undertaken without prior
notification of the geotechnical consultant or approved plans.
All finished cut and fill slopes should be protected from erosion and/or be planted in
accordance with the project specifications and/or as recommended by a landscape
architect. Such protection and/or planning should be undertaken as soon as practical after
completion of grading.
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PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS
I The following preliminary recommendations are provided for consideration in pool/spa
design and planning. Actual recommendations should be provided by a qualified
U geotechnical consultant, based on site specific geotechnical conditions, including a
subsurface investigation, differential settlement potential, expansive and corrosive soil
potential, proximity of the proposed pool/spa to any slopes with regard to slope creep and
I lateral fill extension, as well as slope setbacks per Code, and geometry of the proposed
improvements. Recommendations for pools/spas and/or deck flatwork underlain by
expansive soils, or for areas with differential settlement greater than ¼-inch over 40 feet
horizontally, will be more onerous than the preliminary recommendations presented below.
The 1:1 (h:v) influence zone of any nearby retaining wall site structures should be
delineated on the project civil drawings with the pool/spa. This 1:1 (h:v) zone is defined
as a plane up from the lower-most heel of the retaining structure, to the daylight grade of
the nearby building pad or slope. If pools/spas or associated pool/spa improvements are
constructed within this zone, they should be re-positioned (horizontally or vertically) so that
they are supported by earth materials that are outside or below this 1:1 plane. If this is not
possible given the area of the building pad, the owner should consider eliminating these
improvements or allow for increased potential for lateral/vertical deformations and
associated distress that may render these improvements unusable in the future, unless
they are periodically repaired and maintained. The conditions and recommendations
presented herein should be disclosed to all homeowners and any interested/affected
parties.
I General
The equivalent fluid pressure to be used for the pool/spa design should be
60 pounds per cubic foot (pcf) for pool/spa walls with level backfill, and 75 pcf for
a 2:1 sloped backfill condition. In addition, backdrains should be provided behind
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pool/spa walls subjacent to slopes.
Passive earth pressure may be computed as an equivalent fluid having a density of
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150 pcf, to a maximum lateral earth pressure of 1,000 pounds per square foot (psf).
An allowable coefficient of friction between soil and concrete of 0.30 may be used
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with the dead load forces.
When combining passive pressure and frictional resistance, the passive pressure
I component should be reduced by one-third.
Where pools/spas are planned near structures, appropriate surcharge loads need
I to be incorporated into design and construction by the pool/spa designer. This
includes, but is not limited to landscape berms, decorative walls, footings, built-in
barbeques, utility poles, etc.
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All pool/spa walls should be designed as "free standing" and be capable of
supporting the water in the pool/spa without soil support. The shape of pool/spa
in cross section and plan view may affect the performance of the pool, from a
geotechnical standpoint. Pools and spas should also be designed in accordance
with the latest adopted Code. Minimally, the bottoms of the pools/spas, should
maintain a distance H/3, where H is the height of the slope (in feet), from the slope
face. This distance should not be less than 7 feet, nor need not be greater than
40 feet.
The soil beneath the pool/spa bottom should be uniformly moist with the same
stiffness throughout. If a fill/cut transition occurs beneath the pool/spa bottom, the
cut portion should be overexcavated to a minimum depth of 48 inches, and
replaced with compacted fill, such that there is a uniform blanket that is a minimum
of 48 inches below the pool/spa shell. If very low expansive soil is used for fill, the
fill should be placed at a minimum of 95 percent relative compaction, at optimum
moisture conditions. This requirement should be 90 percent relative compaction
at over optimum moisture if the pool/spa is constructed within or near expansive
soils. The potential for grading and/or re-grading of the pool/spa bottom, and
attendant potential for shoring and/or slot excavation, needs to be considered
during all aspects of pool/spa planning, design, and construction.
If the pool/spa is founded entirely in compacted fill placed during rough grading, the
deepest portion of the pool/spa should correspond with the thickest fill on the lot.
Hydrostatic pressure relief valves should be incorporated into the pool and spa
designs. A pool/spa under-drain system is also recommended, with an appropriate
outlet for discharge.
All fittings and pipe joints, particularly fittings in the side of the pool or spa, should
be properly sealed to prevent water from leaking into the adjacent soils materials,
and be fitted with slip or expandible joints between connections transecting varying
soil conditions.
An elastic expansion joint (flexible waterproof sealant) should be installed to prevent
water from seeping into the soil at all deck joints.
A reinforced grade beam should be placed around skimmer inlets to provide
support and mitigate cracking around the skimmer face.
In order to reduce unsightly cracking, deck slabs should minimally be 4 inches
thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab
reinforcement should be supported to ensure proper mid-slab positioning during
the placement of concrete. Wire mesh reinforcing is specifically not recommended.
Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or
pre-soaking of the slab subgrade is recommended, to a depth of 12 inches
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(optimum moisture content), or 18 inches (120 percent of the soil's optimum
moisture content, or 3 percent over optimum moisture content, whichever is
greater), for very low to low, and medium expansive soils, respectively. This
moisture content should be maintained in the subgrade soils during concrete
placement to promote uniform curing of the concrete and minimize the
development of unsightly shrinkage cracks. Slab underlayment should consist of
a 1-to 2-inch leveling course of sand (S.E.>30) and a minimum of 4 to 6 inches of
Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H
is the height of the slope (in feet), will have an increased potential for distress
relative to other areas outside of the H13 zone. If distress is undesirable,
improvements, deck slabs orflatwork should not be constructed closer than H/3 or
7 feet (whichever is greater) from the slope face, in order to reduce, but not
eliminate, this potential.
Pool/spa bottom or deck slabs should be founded entirely on competent bedrock,
or properly compacted fill. Fill should be compacted to achieve a minimum
90 percent relative compaction, as discussed above. Prior to pouring concrete,
subgrade soils below the pool/spa decking should be throughly watered to achieve
a moisture content that is at least 2 percent above optimum moisture content, to a
depth of at least 18 inches below the bottom of slabs. This moisture content should
be maintained in the subgrade soils during concrete placement to promote uniform
curing of the concrete and minimize the development of unsightly shrinkage cracks.
In order to reduce unsightly cracking, the outer edges of pool/spa decking to be
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bordered by landscaping, and the edges immediately adjacent to the pool/spa,
should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge)
extending to a depth of at least 12 inches below the bottoms of the slabs to mitigate
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excessive infiltration of water under the pool/spa deck. These thickened edges
should be reinforced with two No. 4 bars, one at the top and one at the bottom.
Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at
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18 inches on-center, in both directions. All slab reinforcement should be supported
on chairs to ensure proper mid-slab positioning during the placement of concrete.
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16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump
and water-cement ratio are maintained during concrete placement. Concrete
utilized should have a minimum compressive strength of 4,000 psi. Excessive water
I added to concrete prior to placement is likely to cause shrinkage cracking, and
should be avoided. Some concrete shrinkage cracking, however, is unavoidable.
I 17. Joint and sawcut locations for the pool/spa deck should be determined by the
design engineer and/or contractor. However, spacings should not exceed 6 feet on
center.
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Considering the nature of the 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), should be anticipated. All excavations should be observed by a
representative of the geotechnical consultant, including the project geologist and/or
geotechnical engineer, prior to workers entering the excavation or trench, and
minimally conform to Cal/OSHA ("Type C" soils may be assumed), state, and local
safety codes. Should adverse conditions exist, appropriate recommendations
should be offered at that time by the geotechnical consultant. GSl does not consult
in the area of safety engineering and the safety of the construction crew is the
responsibility of the pool/spa builder.
It is imperative that adequate provisions for surface drainage are incorporated by
I the homeowners into their overall improvement scheme. Ponding water, ground
saturation and flow over slope faces, are all situations which must be avoided to
enhance long-term performance of the pool/spa and associated improvements, and
I reduce the likelihood of distress.
Regardless of the methods employed, once the pool/spa is filled with water, should
it be emptied, there exists some potential that if emptied, significant distress may
occur. Accordingly, once filled, the pool/spa should not be emptied unless
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evaluated by the geotechnical consultant and the pool/spa builder.
For pools/spas built within (all or part) of the Code setback and/or geotechnical
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setback, as indicated in the site geotechnical documents, special foundations are
recommended to mitigate the affects of creep, lateral fill extension, expansive soils
and settlement on the proposed pool/spa. Most municipalities or County reviewers
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do not consider these effects in pool/spa plan approvals. As such, where
pools/spas are proposed on 20 feet or more of fill, medium or highly expansive
soils, or rock fill with limited "cap soils" and built within Code setbacks, or within the
I influence of the creep zone, or lateral fill extension, the following should be
considered during design and construction:
I OPTION A: Shallow foundations with or without overexcavation of the
pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low
to low expansive soils (without irreducible particles greater that 6 inches),
I and the pool/spa walls closer to the slope(s) are designed to be free
standing. GSI recommends a pool/spa under-drain or blanket system (see
attached Typical Pool/Spa Detail). The pool/spa builders and owner in this
I optional construction technique should be generally satisfied with pool/spa
performance underthis scenario; however, some settlement, tilting, cracking,
and leakage of the pool/spa is likely over the life of the project.
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OPTION B: Pier supported pool/spa foundations with or without
I overexcavation of the pool/spa shell such that the pool/spa is surrounded by
5 feet of very low to low expansive soils (without irreducible particles greater
than 6 inches), and the pool/spa walls closer to the slope(s) are designed to
I be free standing. The need for a pool/spa under-drain system may be
installed for leak detection purposes. Piers that support the pool/spa should
be a minimum of 12 inches in diameter and at a spacing to provide vertical
and lateral support of the pool/spa, in accordance with the pool/spa
designers recommendations current applicable Codes. The pool/spa builder
and owner in this second scenario construction technique should be more
I satisfied with pool/spa performance. This construction will reduce settlement
and creep effects on the pool/spa; however, it will not eliminate these
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potentials, nor make the pool/spa "leak-free."
The temperature of the water lines for spas and pools may affect the corrosion
properties of site soils, thus, a corrosion specialist should be retained to review all
I spa and pool plans, and provide mitigative recommendations, as warranted.
Concrete mix design should be reviewed by a qualified corrosion consultant and
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materials engineer.
All pool/spa utility trenches should be compacted to 90 percent of the laboratory
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standard, under the full-time observation and testing of a qualified geotechnical
consultant. Utility trench bottoms should be sloped away from the primary structure
on the property (typically the residence).
Pool and spa utility lines should not cross the primary structure's utility lines (i.e.,
not stacked, or sharing of trenches, etc.).
The pool/spa or associated utilities should not intercept, interrupt, or otherwise
adversely impact any area drain, roof drain, or other drainage conveyances. If it is
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necessary to modify, move, or disrupt existing area drains, subdrains, or tightlines,
then the design civil engineer should be consulted, and mitigative measures
provided. Such measures should be further reviewed and approved by the
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geotechnical consultant, prior to proceeding with any further construction.
The geotechnical consultant should review and approve all aspects of pool/spa and
I flatwork design prior to construction. A design civil engineer should review all
aspects of such design, including drainage and setback conditions. Prior to
acceptance of the pool/spa construction, the project builder, geotechnical.
I consultant and civil designer should evaluate the performance of the area drains
and other site drainage pipes, following pool/spa construction.
I 27. All aspects of construction should be reviewed and approved by the geotechnical
consultant, including during excavation, prior to the placement of any additional fill,
prior to the placement of any reinforcement or pouring of any concrete.
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Any changes in design or location of the pool/spa should be reviewed and
I approved by the geotechnical and design civil engineer prior to construction. Field
adjustments should not be allowed until written approval of the proposed field
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changes are obtained from the geotechnical and design civil engineer.
Disclosure should be made to homeowners and builders, contractors, and any
interested/affected parties, that pools/spas built within about 15 feet of the top of a
I slope, and/or H/3, where H is the height of the slope (in feet), will experience some
movement or tilting. While the pool/spa shell or coping may not necessarily crack,
the levelness of the pool/spa will likely tilt toward the slope, and may not be
I esthetically pleasing. The same is true with decking, flatwork and other
improvements in this zone.
I 30. Failure to adhere to the above recommendations will significantly increase the
potential for distress to the pool/spa, flatwork, etc.
Local seismicity and/or the design earthquake will cause some distress to the
pool/spa and decking or flatwork, possibly including total functional and economic
loss.
The information and recommendations discussed above should be provided to any
contractors and/or subcontractors, or homeowners, interested/affected parties, etc.,
that may perform or may be affected by such work.
JOB SAFETY
General
At GSI, getting the job done safely is of primary concern. The following is the company's
safety considerations for use by all employees on multi-employer construction sites.
On-ground personnel are at highest risk of injury, and possible fatality, on grading and
construction projects. GSl recognizes that construction activities will vary on each site, and
that site safety is the prime responsibility of the contractor; however, everyone must be
safety conscious and responsible at all times. To achieve our goal of avoiding accidents,
cooperation between the client, the contractor, and GSl personnel must be maintained.
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of field personnel on grading
and construction projects:
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Safety Meetings: GSI field personnel are directed to attend contractor's regularly
scheduled and documented safety meetings.
Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel,
I at all times, when they are working in the field.
Safety Flags: Two safety flags are provided to GSI field technicians; one is to be
affixed to the vehicle when on site, the other is to be placed atop the
spoil pile on all test pits.
Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing
amber beacons, or strobe lights, on the vehicle during all field testing.
While operating a vehicle in the grading area, the emergency flasher
on the vehicle shall be activated.
In the event that the contractor's representative observes any of our personnel not
following the above, we request that it be brought to the attention of our office.
Test Pits Location, Orientation! and Clearance
The technician is responsible for selecting test pit locations. A primary concern should be
the technician's safety. Efforts will be made to coordinate locations with the grading
contractor's authorized representative, and to select locations following or behind the
established traffic pattern, preferably outside of current traffic. The contractor's authorized
representative (supervisor, grade checker, dump man, operator, etc.) should direct
excavation of the pit and safety during the test period. Of paramount concern should be
the soil technician's safety, and obtaining enough tests to representthe fill.
Test pits should be excavated so that the spoil pile is placed away from oncoming traffic,
whenever possible. The technician's vehicle is to be placed next to the test pit, opposite
the spoil pile. This necessitates the fill be maintained in a driveable condition.
Alternatively, the contractor may wish to park a piece of equipment in front of the test
holes, particularly in small fill areas or those with limited access.
A zone of non-encroachment should be established for all test pits. No grading equipment
should enter this zone during the testing procedure. The zone should extend
approximately 50 feet outward from the center of the test pit. This zone is established for
safety and to avoid excessive ground vibration, which typically decreases test results.
When taking slope tests, the technician should park the vehicle directly above or below the
test location. If this is not possible, a prominent flag should be placed at the top of the
slope. The contractor's representative should effectively keep all equipment at a safe
operational distance (e.g., 50 feet) away from the slope during this testing.
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The technician is directed to withdraw from the active portion of the fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in
a highly visible location, well away from the equipment traffic pattern. The contractor
should inform our personnel of all changes to haul roads, cut and fill areas or other factors
I that may affect site access and site safety.
In the event that the technician's safety is jeopardized or compromised as a result of the
contractor's failure to comply with any of the above, the technician is required, by company
policy, to immediately withdraw and notify his/her supervisor. The grading contractor's
representative will be contacted in an effort to affect a solution. However, in the interim,
no further testing will be performed until the situation is rectified. Any fill placed can be
considered unacceptable and subject to reprocessing, recompaction, or removal.
In the event that the soil technician does not comply with the above or other established
safety guidelines, we request that the contractor bring this to the technician's attention and
notify this office. Effective communication and coordination between the contractor's
I representative and the soil technician is strongly encouraged in order to implement the
above safety plan.
I Trench and Vertical Excavation
It is the contractor's responsibility to provide safe access into trenches where compaction I testing is needed. Our personnel are directed not to enter any excavation or vertical cut
which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of
instability, has any loose rock or other debris which could fall into the trench; or 3) displays I any other evidence of any unsafe conditions regardless of depth.
All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters,
should be shored or laid back. Trench access should be provided in accordance with
Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any
trench by being lowered or "riding down" on the equipment.
If the contractor fails to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify his/her supervisor.
The contractor's representative will be contacted in an effort to affect a solution. All backfill
not tested due to safety concerns or other reasons could be subject to reprocessing and/or
removal.
If GSI personnel become aware of anyone working beneath an unsafe trench wall or
vertical excavation, we have a legal obligation to put the contractor and owner/developer
on notice to immediately correct the situation. If corrective steps are not taken, GSI then
has an obligation to notify Cal/OSHA and/or the proper controlling authorities.
Donna Drive, LLC Appendix C
File:e:\wpl2\6600\6635a.uge GeoSoils, Inc. Page 15
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TYPE A
------------ Natural grade Proposed grade :1
Colluvium and alluvium (remove)
Typical benching
Bedrock or
approved
native material
See Alternate Details
----------- ---
Natural grade Proposed grade
Colluvium and alluvium (remove
::•: Typical benching
Bedrock or
approved
native material
See Alternate Details
Selection of alternate subdrain details, location, and extent of subdrains should be
evaluated by the geotechnical consultant during grading.
G;Jic. 1 CANYON SUBDRAIN DETAIL Plate C-i
6-inch minimum minimum I 6-inch minimum
6-inch minimum
6-inch
A-i B-i
Filter material: Minimum volume of 9 cubic feet per
lineal foot of pipe. FILTER MATERIAL
Sieve Size Percent Passing
Perforated pipe: 6-inch-diameter ABS or PVC pipe or 1 inch 100
approved substitute with minimum 8 perforations 3/4 inch 90-100
(Y4-inch diameter) per lineal foot in /8 inch 40-100
bottom half of pipe (ASTM D-2751, SDR-35, or No. 4 25-40
ASTM D-1527, Schd. 40). No. 8 18-33
No. 30 5-15
For continuous run in excess of 500 feet, use No. 50 0-7
8-inch-diameter pipe (ASTM D-3034, SDR-35, or No. 200 0-3
ASTM D-1785, Schd. 40).
ALTERNATE i: PERFORATED PIPE AND ALTER MATERIAL
\ \_— 6-inch minimum
_L
6 inch
minimum
Filter fabric
6-inch minimum
A-2
---6-inch minimum
6-inch minimum _i 6-inch minimum
B-2
Gravel Material: 9 cubic feet per lineal foot.
Perforated Pipe: See Alternate 1
Gravel: Clean %-inch rock or approved substitute.
Filter Fabric: Mirafi 140 or approved substitute.
ALTERNATE 2: PERFORATED PIPE, GRAVEL., AND ALTER FABRIC
CANYON SUBDRAIN ALTERNATE DETAILS Plate C-2
- - - - - - - - - - - - - - - - - - -
Toe of slope as shown
on grading plan / ..: .:• .
Original ground surface to be /
restored with compacted fill Compàctéd.Pill.
2D - :. ...... •.•.:.
/
D Anticipated removal of unsuitable material
(depth per geotechnical engineer)
Original ground surface
Back-cut varies. For deep removals,
backcut should be made no steeper
than 1:1 (H:V), or flatter as necessary
for safety considerations.
Provide a 1:1 (H:V) minimum projection from toe of
slope as shown on grading plan to the recommended
removal depth. Slope height, site conditions, and/or
local conditions could dictate flatter projections.
FILL SLOPE TOEING OUT ON FLAT ALLUVIATED CANYON DETAIL I Plate C-3
- - - - - - - - - - - - - - - - - - -
Proposed grade
Proposed additional compacted fill
Previously placed, temporary
compacted fill for drainage only
.............. .......
........... . ...... ......./ -
iJnsuitabIe material (to be removed)
Existing compacted fill /
Bedrock or approved
native material
To be removed before placing -
additional compacted fill
REMOVAL ADJACENT TO EXISTING FILL ADJOINING CANYON FILL DETAIL I Plafe C-4
- - - - - - - - - - - - - - - - - -
Drainage per design
civil engineer
Blanket fill (d recommended by
the geotechnical consultant)
Design finish slope
15 foot
minimum
7 10-foot minimum
7 25-foctmaximum
1510ot typicaj
f -
drain spacing /
LL F777
ito 2
2-foot minimum k, Toe key depth
I 15-foot minimum
or H/2 where H is the
I dope height
Buttress or
stabilization fill
Typical
benching
(4-foot
minimum)
'i- Bedrock or
approved native
material
Subdrain as
recommended by
geotechnical consultant
Typical benching
4-inch-diameter non-perforated
outlet pipe and backdrain (see
detail Plate C-6). Outlets to be
spaced at 100-foot maximum
intervals and shall extend 2 feet
beyond the face of slope at time
of rough grading completion. At
the completion of rough grading.
the design civil engineer should
provide recommendations to
convey any outlet's discharge to
a suitable conveyance, utilizing a
non-erosive device.
2-Percent Gradient
Heel
TYPICAL STABILIZATION / BUTTRESS FILL DETAIL Plate C-5
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minimum I
4-inch mim
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2-inch minim
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Pe ............[nm
_:
2-foot • I
minimum 2-toot
I mum
4-mch
mmium— 2-inch
pipe minimum
Filter Material: Minimum of 5 cubic feet per lineal foot of pipe or 4 cubic feet per lineal
feet of pipe when placed in square cut trench.
Alternative in Lieu of Filter Material: Gravel may be encased in approved filter fabric.
Filter fabric shall be Mirafi 140 or equivalent. Filter fabric shall be lapped a minimum of
12 inches in all joints.
Minimum 4-Inch-Diameter Pipe: ABS-ASTM D-2751, SDR 35; or ASTM D-1527 Schedule
40, PVC-ASTM D-3034, SDR 35; or ASTM D-1785 Schedule 40 with a crushing strength
of 1,000 pounds minimum, and a minimum of 8 uniformly-spaced perforations per foot of
pipe. Must be installed with perforations down at bottom of pipe. Provide cap at
upstream end of pipe. Slope at 2 percent to outlet pipe. Outlet pipe to be connected
to subdrain pipe with tee or elbow.
Notes: 1. Trench for outlet pipes to be backfilled and compacted with onsite soil.
2. Backdrains and lateral drains shall be located at elevation of every bench
drain. First drain located at elevation just above lower lot grade. AdditionJ
drains may be required at the discretion of the geotechnical consultant.
Filter Material shall be of the following Gravel shall be of the following
specification or an approved equivalent, specification or an approved equivalent.
Sieve Size Percent Passing Sieve Size Percent Passing
1 inch 100 iY2 inch 100
1/4 inch 90-100 No. 4 50
/8 inch 40-100 No. 200 8
No. 4 25-40
No. 8 18-33
No. 30 5-15
No. 50 0-7
No. 200 0-3
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Gi aC. I TYPICAL BUTTRESS SUBDRAIN DETAIL Plate C-6
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- - - - - - - - . - - - - - - - - - - Proposed grade
Toe of slope as shown
on grading plan \ .-
acted fill Natural slope to Comp
. .
be restored •th
compacted fill
•. :.
7.
.. •• :
Backcut varies or foot minimum
O
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2-foot minum •• . .. E ........ .
Benchwth
in bedrock may vary -.j Bedrock or or
-
3-foot minimum I (4-foot minimum) I approved approved
earth material native material . \ 2-Percent Gradient ---
__\\
-~17.\\\4\ --i
15-foot minimum or
H/2 where H is Subdrain as recommended by
the slope height I geotechnical consultant
NOTES:
Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be
provided by the geotechnical consultant.
The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon
exposed conditions.
FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate C-7
- - - - - - - - - - - - - - - - - - -
Cut/fill contact as
shown on grading plan
___
Proposed grade
Cut/fill contact as \ Maintain \ Compacted fill shown on as-built plan minimum 15-foot-
fill section from
backcut to face . . . . .
of finish slope . .
1 •. H - height of slope - . 4-foot minimum
Original (existing) grade
'- Bench width
-percent —may vary
Cut slope
minimum
key depth I Subdrain as recommended by
I the slope height 1 geotechnical consultant
Bedrock or approved
native material
NOTE: The cut portion of the slope should be excavated and evaluated by the geotechnical consultant prior to
construction of the fill portion.
G" FILL OVER CUT DETAIL Plate C-8
- - - - - - - - - - - - - - - - - - - Natural slope
2 Percent Gradient --
consultant, the remaining cut portion of
the slope may require removal and
replacement with compacted fill.
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- Subdrain as recommended by
geotechnical consultant
NOTES: 1. Subdrains may be required as specified by the geotechnical consultant.
2 W shall be equipment width (15 feet) for slope heights less than 25 feet. For slopes greater than
25 feet, W shall be evaluated by the geotechnical consultant. At no time, shall W be less than H/2,
where H is the height of the slope.
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G4nc. STABLIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN CUT SLOPE DETAIL Plate C-9
- - - - - - - - - - - - - - - - - - - Proposed finish grade Natural grade
-------------------------
minimum
........
H - height of slope .
: 15- t minimum
::.••. see Note 1)
. \\ Bedrock or
-.•
\ \\\ approved
native material 0.
Typical benching
(4-foot minimum)
2-Percent
2-foot minimum _J - key depth 15-foot minimum key widtl p or H12 If H)30 feet I Subdrain as recommended by
geotechnical consultant
NOTES: 1. 15-foot minimum to be maintained from proposed finish slope face to backcut.
2. The need and disposition of drains will be evaluated by the geotechnical consultant based on field conditions.
Pad overexcavation and recompaction should be performed if evaluated to be necessary by the
geotechnical consultant.
IG#F I se. I SKIN FILL OF NATURAL GROUND DETAIL Plate C-10
- - - - - - - - - - - - - - - - - - -
Reconstruct compacted fill slope at 2:1 or flatter Natural grade .
(may increase or decrease pad area) .
Overexcavate and recompact • : .. . I
replacement fill
. .Remov
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Proposed unsuitable atenl.....
Back-cut varies
/
finish grade
p,'.
•. ..:. . : 3-foot minimum fill blanket
Avoid and/or clean up ........
t ... I. I : \ -
spillage of materials on
the natural slope
.....
Bedrock or approved
2-foot minimum native material
key dth
..
... . >.. . Typical benching
- - - - - •. ----. -- 2-percent gradient (4-foot minimum)
----
\
I Subdrain as recommended by
\\)\\\ geotechnical consultant
NOTES: 1. Subdrain and key width requirements will be evaluated based on exposed subsurface conditions and
thickness of overburden.
2. Pad overexcavation and recompaction should be performed if evaluated necessary by the geotechnical
consultant.
DAYLIGHT CUT LOT DETAIL I Plate C-i 1
Natural grade
Proposed pad grade
tw
Mato me
Subrade at 2 percent aradient. drainina toward street
3- to 7-foot minimum*
overexcavate and recompact
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Bedrock or per text of report
approved native
material
Typical benching
CUT LOT OR MATERIAL-TYPE TRANSITION
IProposed pad grade Natural grade
is
Subgrade at 2 percent gradient, draining toward street
\)- 3- to 7-foot minimum. -
overexcavate and recompact
per text of report
* Deeper overexcavat:n may be
recommended by the geotechnical Bedrock or consultant in steep cut-fill transition \ approved native areas, such that the underlying
Typical benching material topography is no steeper than 3:1 (H:V)
(4-foot minimum)
CUT-FILL LOT (DAYLIGHT TRANSITION)
TRANSITION LOT DETAILS Plate C-12
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Bedrock or approved
native material
VIEW NORMAL TO SLOPE FACE
Proposed finish grade
(E)
a(E) Hold-down depth
co Go
I 5-fo0 t I (B)
minimum
co co cD (A)
------ ,,-.
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minimum native material
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VIEW PARALLEL TO SLOPE FACE
Proposed finish grade
(B) (E) Hold-down depth 100-foot .
I maximum I
3-toot minimum 15-foot minimum
- 25-foot minimum
-. )\j from
\YOfl wall
(C)
5-toot —J
minimum
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NOTES:
One equipment width or a minimum of 15 feet between rows (or windrows).
Height and width may vary depending on rock size and type of equipment. Length of windrow
shall be no greater than 100 feet.
If approved by the geotechnical consultant, windrows may be placed direclty on competent
material or bedrock, provided adequate space is available for compaction.
Orientation of windrows may vary but should be as recommended by the geotechnical engineer
and/or engineering geologist. Staggering of windrows is not necessary unless recommended.
Clear area for utility trenches, foundations, and swimming pools; Hold-down depth as specified in
text of report, subject to governing agency approval.
All fill over and around rock windrow shall be compacted to at least 90 percent relative
compaction or as recommended.
After fill between windrows is placed and compacted, with the lift of fill covering windrow, windrow
should be proof rolled with a D-9 dozer or equivalent.
VIEWS ARE DIAGRAMMATIC ONLY AND MAY BE SUPERSEDED BY REPORT RECOMMENDATIONS OR CODE
ROCK SHOULD NOT TOUCH AND VOIDS SHOULD BE COMPLETELY FILLED
G4 w. OVERSIZE ROCK DISPOSAL DETAIL Plate C-13
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ROCK DISPOSAL P118
Fill lifts compacted over
rock after embedment
F
- 2T - - - Granular material
L_.__... .:•:•:•:• Large Rock -----------1
Size of excavation to I
I Compacted Fill be commensurate I
with rock size
ROCK DISPOSAL LAYERS
Granular soil to fill voids, densified by flooding Compacted fill
rock high
Proposed finish grade
Hold-downdepth
ZOvereeizelaye
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PROFILE ALONG LAYER
* Hold-down depth
I Compacted fill
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3-foot
minimum
Fill Slope
. Clear zone TOP VIEW
* Hold-down depth or below lowest utility as specified in text of report subject to governing agency approval.
. Clear zone for utility trenches, foundations, and swimming pools, as specified in text of report.
VIEWS ARE DIAGRAMMATIC ONLY AND MAY BE SUPERSEDED BY REPORT RECOMMENDATIONS OR CODE
IL ROCK SHOULD NOT TOUCH AND VOIDS SHOULD BE COMPLETELY FILLED IN
G*6JJJic. ROCK DISPOSAL DETAIL Plate C-14
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Layer one rock high
,r Existing grade
5-foot-high
impact/debris wall METHOD 1
Pad grade
-
5-foot-high
impact/debris wall METHOD 2
Pad grade
Existing grade
5-foot-wide catchment area
5-foot-high METHOD 3
\ /" impact/debris wa
llPad grade
Existing grade
21 NO slope Fence
J1TI,/ 2:1 NO slope METHOD 4
Pad grade
NOT TO SCALE
[G" J1C.I DEBRIS DEVICE CONTROL METHODS DETAIL Plate C-15
Rock-filled
gabion basket
Existing grade 5-toot minimum or as
recommended by
geotechnical conauftant Proposed grade
Filter fabric Drain rock
Compacted fill
Gabion impact or diversion wall should be constructed at the base of the
ascending slope subject to rock fall. Walls need to be constructed with high
segments that sustain impact and mitigate potential for overtopping, and low
segment that provides channelization of sediments and debris to desired
depositional area for subsequent clean-out. Additional subdrain may be
recommended by geotechnical consultant.
From GSA, 1987
GWbc. ROCK FALL MITIGATION DETAIL Plate C-16
n 4-inch perforated I subdrain pipe I (transverse)
Pool
B'
Direction
of drainage
cRoss SECTION VIEW
NOT TO SCALE
SEE NOTES
Coping
Pool encapsulated in 5-foot
thickness of sand
MAP VIEW
NOT TO SCALE Concrete cut-oft wall SEE NOTES
Top of slope
Gravity-flow, —"
nonperforated subdrain
pipe (transverse)
Toe of slope
4-inch perforated
subdrain pipe
(longitudinal)
A i i coping
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Pool
........................................... ........................................... ...........................................
2-inch-thick
sand layer
Vapor retarder —' \ 6-inch-thick gravel layer
4-inch perforated subdrain pipe
B Coping
-
B'
5 feet
Outlet per
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engineercivil
8
Dwess
7
Pool
t _
gravel layer :•:•:•••.•.•.•.•..•....•...•..•...•..•..•.•:.•.•.•..•.•.
,7 2-inch-thick sand layer
Gravity-flow nonperforated--/Concrete _,/ Vapor retarder subdrain pipe cut-off wall Perforated subdrain pipe
NOTES:
t 6-inch-thick, clean gravel (3% to 1Y2 inch) sub-base encapsulated in Mirafi 140N or equivalent, underlain by
a 15-mil vapor retarder, with 4-inch-diameter perforated pipe longitudinal connected to 4-inch-diameter
perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point
and outlet or to sump pump area.
Pools on fills thicker than 20 feet should be constructed on deep foundations; otherwise, distress (tilting,
cracking, etc.) should be expected.
Design does not apply to infinity-edge pools/spas.
6 as Ec. : TYPICAL POOL/SPA DETAIL Plate C-17
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2-foot x 2-foot x 3-inch steel plate
3tandard 3/4-inch pipe nipple
velded to top of plate
,-inch x 5-foot galvanized pipe,
andard pipe threads top and bottom;
(tensions threaded on both ends and
lded in 5-foot increments
3-inch schedule 40 PVC pipe sleeve, add
n 5-foot increments with glue joints
y Iroposed tinish grade
- -1w----- -- liii I -
1111 ll J-
1rll_- -r
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1711-
51eet 51eet
5 feet
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___,••••.. .
. ....... .. -
_____ / Bottom of cleanout
l foot ________ Provide a minimum 1-foot
bedding of compacted sand
NOTES:
Locations of settlement plates should be clearly marked and readily visible (red flagged) to
equipment operators.
Contractor should maintain clearance of a 5-foot radius of plate base and withiin 5 feet (vertical)
for heavy equipment. Fill within clearance area should be hand compacted to project
specifications or compacted by alternative approved method by the geotechnical consultant (in
writing, prior to construction).
After 5 feet (vertical) of fill is in place, contractor should maintain a 5-foot radius equipment
clearance from riser.
Place and mechanically hand compact initial 2 feet of fill prior to establishing the initial reading.
In the event of damage to the settlement plate or extension resulting from equipment operating
within the specified clearance area, contractor should immediately notify the geotechnical
consultant and should be responsible for restoring the settlement plates to working order.
An alternate design and method of installation may be provided at the discretion of the
geotechnical consultant.
I G4 Go I !,c. SETTLEMENT PLATE AND RISER DETAIL Plate C-18
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Finish grade
3/8-inch-diameter X 6-inch-long
carriage bolt or equivalent
6-inch diameter X
3 to 6 feet 3Y2-inch-long hole
- Concrete backfill
TYPICAL SURFACE SETTLEMENT MONUMENT Plate C-19
SIDE VIEW
Test pit
TOP VIEW
Flag Flag
Spoil pile Test pit
Light
Vehicle
50 feet 50 feet
-100 feet
Ge$Jic. TEST PIT SAFETY DIAGRAM Plate C-20