HomeMy WebLinkAboutCUP 12-05; Alps Innovation Staybridge Suites & Holiday Inn; Conditional Use Permit (CUP) (4)GEOTECHNICAL UPDATE INVESTIGATION,
PROPOSED BRESSI RANCH HOTELS,
LOT 1 OF CARLSBAD TRACT CT-06-20
(PL7\NNING AREA PA-4, BRESSI RANCH),
CARLSBAD, CALIFORNIA
Prepared For
PRIME GROUP CONSTRUCTION, INC.
PO Box 800521
Santa Clarita, CA. 91380
RECEIVED
MAR 1 1 7m
CITY OF CARLSBAD
PLANNING DIVISION
Project No. 603446-001
May 15, 2012
Leighton Consulting, Inc.
A LEIGHTON GROUP COMPANY
Leighton Consulting, Inc.
A LEIGHTON GROUP COMPANY
May 15, 2012
Project No. 603446-001
To: Prime Group Construction, Inc.
PO Box 800521
Santa Clarita, CA. 91380
Attention: Mr. Joey Blagg
Subject: Geotechnical Update Investigation, Proposed Bressi Ranch Hotels, Lot 1
of Carlsbad Tract CT-06-20 (Planning Area PA-4, Bressi Ranch),
California
In accordance with your request and authorization, we have conducted a geotechnical
update investigation for the proposed Bressi Ranch Hotels on Lot 1 of Carlsbad Tract
CT-06-20 (Planning Area PA-4, Bressi Ranch), California. Based on the results of our
study, it is our professional opinion that the site is suitable for the proposed commercial
development and associated improvements. The accompanying report presents a
summary of our update investigation and provides preliminary geotechnical conclusions
and recommendations relative to the proposed site development.
If you have any questions regarding our report, please do not hesitate to contact this
office. We appreciate this opportunity to be of service.
Respectfully submitted,
LEIGHTON CONSULTING, INC.
William D. Olson, RCE 45283
Associate Engineer
Distribution: (4) Addressee
Mike Jensen, CEG 2457
Project Geologist
3934 Murphy Canyon Road, Suite B205 • San D\ego7Cf(^ 23-4425
858.292.8030 • Fax 858.292.0771
603445-001
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION 1
1.1 PURPOSE AND SCOPE 1
1.2 SITE LOCATION AND DESCRIPTION 1
1.3 PROPOSED DEVELOPMENT 2
2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING 3
3.0 SUMMARY OF GEOTECHNICAL CONDITIONS 4
3.1 GEOLOGIC SETTING 4
3.2 AS-GRADED GEOLOGIC CONDITIONS 4
3.3 SITE-SPECIFIC GEOLOGY 4
3.3.1 Artificial Documented Fill (Map Symbol-Af) 5
3.3.2 Santiago Formation (Map Symbol-Tsa) 5
3.4 SURFACE AND GROUND WATER 6
3.5 GRADED SLOPES 6
4.0 FAULTING AND SEISMICITY 7
5.0 CONCLUSIONS 9
6.0 RECOMMENDATIONS 10
6.1 EARTHWORK 10
6.1.1 Site Preparation 10
6.1.2 Mitigation of Cut/Fill Transition Conditions 11
6.1.3 Mitigation of High to Very High Expansive Soils at Finish Grade 11
6.1.4 Excavations 12
6.1.5 Fill Placement and Compaction 12
6.2 FOUNDATION DESIGN CONSIDERATIONS 13
6.2.1 Moisture Conditioning 14
6.2.2 Foundation Setback 15
6.2.3 Anticipated Settlement 15
6.3 LATERAL EARTH PRESSURES 16
6.3 LATERAL EARTH PRESSURES 16
6.4 FENCES AND FREESTANDING WALLS 18
6.5 CONCRETE FLATWORK 19
6.6 PROPOSED SWIMMING POOLS 19
6.6.1 Pool Deck Recommendations 20
6.7 GEOCHEMICAL CONSIDERATIONS 21
6.8 PRELIMINARY PAVEMENT DESIGN 21
6.9 CONTROL OF SURFACE WATER AND DRAINAGE 23
6.10 SLOPE MAINTENANCE GUIDELINES 24
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TABLE OF CONTENTS fContinuedl
Section Page
6.11 LANDSCAPING AND POST-CONSTRUCTION 25
6.12 CONSTRUCTION OBSERVATION AND TESTING 26
7.0 LIMITATIONS 27
TABLES
TABLE 1 - PRESATURATION RECOMMENDATIONS BASED ON FINISH GRADE
SOIL EXPANSION POTENTIAL - PAGE 14
TABLE 2 - MINIMUM FOUNDATION SETBACK FROM DESCENDING SLOPE FACES - PAGE 15
TABLE 3 - LATERAL EARTH PRESSURES - PAGE 17
TABLE 4 - PRELIMINARY PAVEMENT SECTION DESIGNS - PAGE 22
FIGURE
FIGURE 1 - SITE LOCATION MAP - AT END OF TEXT
PLATE
PLATE 1 - GEOTECHNICAL MAP - IN POCKET
APPENDICES
APPENDIX A - REFERENCES
APPENDIX B - LEIGHTON 2006 TEST PIT LOGS
APPENDIX C - LEIGHTON 2006 LABORATORY TESTING PROCEDURES AND TEST RESULTS
APPENDIX D - GENERAL EARTHWORK AND GRADING SPECIFICATIONS
APPENDIX E-ASFE
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1.0 INTRODUCTION
1.1 Purpose and Scope
This report presents the results of our geotechnical update investigation for
proposed Bressi Ranch Hotels on Lot 1 of Carlsbad Tract CT-06-20 (Planning
Area PA-4, Bressi Ranch), California (Figure 1). The purpose of our geotechnical
update investigation was to evaluate existing geotechnical conditions present at
the site and to provide preliminary geotechnical conclusions and
recommendations relative to the proposed commercial development.
As part of our update investigation ofthe site, we performed the following:
• Review of available pertinent, published and unpublished geotechnical
reports, geologic literature, and maps (Appendix A).
• Field reconnaissance ofthe existing onsite geotechnical conditions.
• Compilation and analysis of the geotechnical data obtained from the field
investigation and laboratory testing.
• Preparation of this report presenting our findings, conclusions, and
geotechnical recommendations (including General Earthwork and Grading
Specifications presented as Appendix D) with respect to the proposed design,
site grading, and general construction considerations.
1.2 Site Location and Description
The site for proposed hotel consists of a rectangular shaped property bordered
on the north by Palomar Airport Road, on the west by Innovation Way. The total
area of the proposed project is 9.2 acres and covered with vegetation consisting
of native grasses and weeds. As background, the mass grading operations for
overall area. Planning Area PA-4 and the associated streets was performed
between September 2003 and May 2004 (Leighton, 2004c). The rough grading
resulted in a generally southwest sloping sheet-graded pad. The mass graded
pad elevation ranged from approximately 374 feet mean sea level (msl) in the
southwest portion ofthe site to 403 feet msl in the northeast portion. The grading
operations were performed by Nelson and Belding while Leighton and
Associates performed the geotechnical observation and testing services.
Grading of the site included: 1) the removal of potentially compressible
desiccated older fill soils, undocumented fill soils, topsoil, colluvium, alluvium,
and weathered formational material; 2) the excavation of fill slope and stability fill
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keys; 3) preparation of areas to receive fill; 4) the placement of a subdrain in the
canyon bottom; 5) excavation of formational material; and 6) the placement of
compacted fill soils.
In 2006 and 2007, the site was partially fine graded for proposed commercial
building pads and improvements associated with the construction of The Towers
at Bressi Ranch, a commercial development project that is located immediately
south of the subject site. The fine-grading of the site included: 1) overexcavation
of the cut/fill transitions; 2) preparation of areas to receive fill; 3) construction of fill
over cut slopes, fill slopes, and a replacement fill slope along the west side of Colt
Place; 4) excavation of cut material, and 5) the placement of compacted fill. The
approximate bottom elevations density tests, and limits of fill for the previously
proposed building pad areas are presented on the Geotechnical Map (Plate 1).
1.3 Proposed Development
The overall proposed development is anticipated to consist of two three-story
hotel buildings, two pools, driveways, parking areas, underground utilities, minor
slopes, and associated open areas or landscaped areas (Prime, 2012). We
understand that the proposed buildings will be wood framed structures (Type V-A
construction) with concrete slab-on-grade foundations. Currently, precise grading
plans were not available; however, we anticipate that the proposed site grades
will remain close to existing grades (i.e., relatively minor cuts and fills to achieve
site grade and a balanced site).
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2.0 SUBSURFACE EXPLORATION AND LABORATORY TESTING
In 2006, our subsurface investigation of PA-4 included the excavation of 25 exploratory
test pits across to depths ranging from approximately 5 to 9 feet below the existing
ground surface (bgs) of which 7 test pits (TP- 1 through TP-7) were performed on the
subject site. The purpose of these excavations was to evaluate the engineering
characteristics of the onsite soils with regard to the proposed development. The test
pits allowed evaluation of the onsite soils, including those likely to be encountered at
the proposed foundation elevations and provided representative samples for laboratory
testing. Logs ofthe 7 test pits (TP-1 through TP-7) are presented in Appendix B.
The exploratory excavations were logged by a geologist from our firm. Representative
bulk samples were obtained at selected intervals for laboratory testing. The
approximate locations of the test pits are shown on the Geotechnical Map (Plate 1).
Subsequent to logging and sampling, the test pits were backfilled with native soils and a
compactive effort was applied utilizing a backhoe with a sheeps foot wheel, and wheel
rolling to achieve the desired compaction. The compactive effort was observed by a
representative from our firm, however no testing was performed.
Laboratory testing for the 2006 subsurface investigation of PA-4 was performed on
representative samples to evaluate the R-value, expansion potential, soluble sulfate
and chloride contents, and minimum resistivity and pH tests. A discussion of the
laboratory tests performed and a summary of the laboratory test results are presented
in Appendix C.
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3.0 SUMMARY OF GEOTECHNICAL CONDITIONS
3.1 Geologic Setting
The subject site is located in the coastal section of the Peninsular Range
Province, a geomorphic province with a long and active geologic history
throughout Southern California. Throughout the last 54 million years, the area
known as the "San Diego Embayment" has undergone several episodes of
marine inundation and subsequent marine regression, resulting in the deposition
of a thick sequence of marine and nonmarine sedimentary rocks on the
basement rock ofthe Southern California batholith.
Gradual emergence of the region from the sea occurred in Pleistocene time, and
numerous wave-cut platforms, most of which were covered by relatively thin
marine and nonmarine terrace deposits, formed as the sea receded from the
land. Accelerated fluvial erosion during periods of heavy rainfall, coupled with the
lowering of the base sea level during Quaternary time, resulted in the rolling hills,
mesas, and deeply incised canyons which characterize the landforms we see in
the general site area today.
3.2 As-graded Geologic Conditions
The geologic or geotechnical conditions encountered during our current update
study of the site were essentially as anticipated. A comprehensive summary ofthe
geologic conditions (including geologic units, geologic structure, and faulting) are
presented below.
3.3 Site-Specific Geology
The geologic units encountered during our previous investigation and site
grading consisted of artificial documented fill soils and the Santiago Formation.
The approximate limits of the geologic units encountered are presented on the
Geotechnical Map (Plate 1) and discussed (youngest to oldest) below.
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3.3.1 Artificial Documented Fill ^Map Svmbol-Af)
Documented fill soils placed during the prior grading operations that were
observed and tested by Leighton and Associates are generally located
along the western perimeter, a central section and in the southeast corner
of the site (as indicated on Plate 1). In addition to the fill limits, the
elevations of the bottom of the fill are provided on the geotechnical map so
that potential fill differentials across the site can be identified. Note that the
older fill associated with original mass grading of Bressi Ranch was
designated using "Afo".
The field density test results presented in the as-graded geotechnical report
for the project (Leighton, 2004c and 2007) indicated the fill soils were
placed and compacted to at least a 90 percent relative compaction with
moisture contents at or near the optimum moisture content.
During our update study, the upper portion of the fill soils was found to be
desiccated and minimal removals and/or scarification and recompaction will
be necessary prior to the placement of additional fill or structural
improvements. The fill soils typically consisted of silty sands, clayey sands,
and to a lesser extent sandy to silty clays. Based on our review of the as-
graded geotechnical report (Leighton, 2004c and 2007), the fill soils on this
site are up to approximately 6 feet in depth at various locations.
3.3.2 Santiago Formation (Mao Svmbol-Tsa)
The Tertiary-aged Santiago Formation, as encountered during our update
study, consisted primarily of massively bedded sandstones, and to a
lesser extent claystones and siltstones. The sandstone generally
consisted of orange-brown (iron oxide staining) to light brown, damp to
moist, dense to very dense, silty very fine to medium grained sandstone.
The siltstones and claystones were generally olive-green, damp to moist,
stiff to hard, moderately weathered, and occasionally fractured and
moderately sheared.
Several well-cemented fossiliferous sandstone beds and clay seams were
encountered during the mass grading (Leighton, 2004c) at the site. The
clay seam generally trending in a north-south direction is present in the
eastern portion ofthe site (as indicated on Plate 1). Subsequently, the clay
seam (which is a relatively thin 1 to 2 inch thick plastic clay bed) was
mitigated by overexcavating during the fine grading for the previously
proposed commercial buildings. Currently, the clay seam is not
anticipated to be beneath the proposed eastern building footprint or within
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the upper 3 feet of a proposed surface grades, and is not considered a
constraint to development at this time. The well-cemented fossiliferous
sandstone beds may be present in the Santiago Formation near the
surface or at depth. Deep excavations should be anticipated the well-
cemented beds and be prepared to utilized larger excavations, breakers,
and single-shank ripper to excavate trenches.
3.4 Surface and Ground Water
No indication of surface water or evidence of surface ponding was observed site
visit or during our previous fine grading of the site (Leighton, 2007). However,
surface water may drain as sheet flow across the site during rainy periods and
accumulate in lower elevations and in the on-site desilting basin. Ground water
was not observed in the test pits during our investigation or during our previous
fine grading of the site (Leighton, 2007); however, perched ground water levels
may develop and fluctuate during periods of precipitation and after initial
landscaping and irrigation has been installed.
3.5 Graded Slopes
Graded and natural slopes within the developed portion of the tract are considered
grossly and surficially stable from a geotechnical standpoint. Manufactured cut and
fill slopes within the tract were surveyed by the civil engineer are understood to
have been constructed with slope inclinations of 2:1 (horizontal to vertical) or
flatter.
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4.0 FAULTING AND SEISMICITY
Our discussion of faults on the site is prefaced with a discussion of California legislation
and state policies concerning the classification and land-use criteria associated with
faults. By definition of the California Mining and Geology Board, an active fault is a fault
that has had surface displacement within Holocene time (about the last 11,000 years).
The State Geologist has defined a potentiallv active fault as any fault considered to have
been active during Quaternary time (last 1,600,000 years) but that has not been proven to
be active or inactive. This definition is used in delineating Fault-Rupture Hazard Zones as
mandated by the Alquist-Priolo Earthquake Fault Zoning Act of 1972 and as most recently
revised in 2007. The intent of this act is to assure that unwise urban development does
not occur across the traces of active faults. Based on our review of the Fault-Rupture
Hazard Zones, the site is not located within any Fault-Rupture Hazard Zone as created by
the Alquist-Priolo Act (Bryant and Hart, 2007).
San Diego, like the rest of southern California, is seismically active as a result of being
located near the active margin between the North American and Pacific tectonic plates.
The principal source of seismic activity is movement along the northwest-trending
regional fault zones such as the San Andreas, San Jacinto and Elsinore Faults Zones,
as well as along less active faults such as the Rose Canyon Fault Zone. As indicated in
the Supplemental Geotechnical Report for the Bressi Ranch project (Leighton, 2001),
there are no known major or active faults on or in the immediate vicinity of the site. The
nearest known active fault is the Rose Canyon Fault Zone, which is located approximately
7.0 miles (11.2 kilometers) west of the site.
As discussed above, evidence of active faulting was not encountered within the site
during the mass grading operations in 2003-2004 (Leighton, 2004b). However, several
minor inactive faults were encountered within the limits of the Bressi Ranch development
that are not considered a constraint to development of Planning Area 2. Geologic
mapping of the onsite minor faults, where topsoil was encountered over the faults,
indicated that the faults did not extend into or offset the topsoil, suggesting that the faults
are not active.
Because of the lack of known active faults on the site, the potential for surface rupture at
the site is considered low. Shallow ground rupture due to shaking from distant seismic
events is not considered a significant hazard, although it is a possibility at any site.
However, due to the presence of slopes on-site, lurching and associated ground
cracking near the tops of slopes is possible.
Liquefaction and dynamic settlement of soils can be caused by strong vibratory motion
due to earthquakes. Both research and historical data indicate that loose, saturated,
granular soils are susceptible to liquefaction and dynamic settlement. Liquefaction is
typified by a loss of shear strength in the affected soil layer, thereby causing the soil to
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act as a viscous liquid. This effect may be manifested by excessive settlements and
sand boils at the ground surface. The fill and formational materials underlying the site
are not considered liquefiable due to their fine-grained nature, dense physical
characteristics, and unsaturated condition.
The following seismic design parameters for the site have been determined in
accordance with the 2010 California Building Code (CBC) and the USGS Ground
Motion Parameter Calculator (Version 5.10).
Seismic Design Parameters
Description Values CBC Reference
Site Class D Table 1613.5.2
Short Period Spectral Acceleration Ss 1.133 Figure 1613.5(3)
1-Second Period Spectral Acceleration Si 0.422 Figure 1613.5(4)
Short Period Site Coefficient Fa 1.055 Table 1613.5.3(1)
1-Second Period Site Coefficient Fv 1.578 Table 1613.5.3(2)
Adjusted Short Period Spectral Acceleration SMS 1.175 Equation 16-36
Adjusted 1 -Second Period Acceleration SMI 0.666 Equation 16-37
Design Short Period Spectral Response
Parameter SDS 0.783 Equation 16-38
Design 1-Second Period Spectral Response
Parameter SDI 0.444 Equation 16-39
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5.0 CONCLUSIONS
Based on the results of our update geotechnical study of the site, it is our professional
opinion that the proposed commercial development is feasible from a geotechnical
standpoint, provided the following conclusions and recommendations are incorporated
into the project plans and specifications.
The following is a summary of the geotechnical factors that may affect development of
the site.
• Based on our site visit, the near-surface fill soils are locally disturbed (i.e., the upper
1 to 2 feet). These soils are not considered suitable for support of additional fill soils,
structural loads or surface improvements in their present condition. Remedial
grading measures such as scarification, removals and recompaction will be
necessary to mitigate this condition if the disturbed soils are not removed by the
proposed excavation. In addition, building and settlement sensitive structures
located on cut/fill transition will require remedial grading to minimize potential
differential settlements and/or expansion potential.
• Cut/fill transition conditions present beneath proposed buildings will need to be
mitigated by the overexcavation of the cut portion of the building pad to at least 2
feet below the proposed footing bottoms. Once final civil plans are completed an
additional review will need to be performed to evaluate cut/fiil transitions.
• Based on previous laboratory testing and visual classification, the fill soils on the site
generally possess a very low to medium expansion potential.
• Laboratory test results indicate the fill soils present on the site have a negligible to
severe potential for sulfate attack on normal concrete, and are moderately to
severely corrosive on buried metal pipes and conduits.
• The existing onsite soils appear to be suitable material for reuse as fill provided they
are relatively free of organic material, debris, and rock fragments larger than 8
inches in maximum dimension.
• Near surface ground water or seepage was not encountered during our investigation
however, perched ground water and seepage may develop during periods of
precipitation and after site irrigation.
• Although foundation plans have not been finalized nor building loads developed, we
anticipate that conventional foundation system, consisting of continuous and spread
footings with slab-on-grade flooring supported by competent fill or formational
materials, will be used.
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6.0 RECOMMENDATIONS
6.1 Earthwork
We anticipate that future earthwork at the site will consist of site preparation, fine
grading, utility trench excavation and backfill, small retaining wall backfill, and
driveway and parking area pavement section preparation and compaction. We
recommend that the earthwork on site be performed in accordance with the
following recommendations, the General Earthwork and Grading Specifications
for Rough Grading included in Appendix D, and the City of Carlsbad grading
requirements. In case of conflict, the following recommendations shall supersede
those in Appendix D. The contract between the developer and earthwork
contractor should be worded such that it is the responsibility of the contractor to
place the fill properly and in accordance with the recommendations of this report
and the specifications in Appendix D, notwithstanding the testing and
observation of the geotechnical consultant.
6.1.1 Site Preparation
During future grading, the areas to receive structural fill or engineered
structures should be cleared of surface obstructions, potentially
compressible material (such as desiccated fill soils or weathered
formational material), and stripped of vegetation. Vegetation and debris
should be removed and properly disposed of off site. Holes resulting from
removal of buried obstructions that extend below finish site grades should
be replaced with suitable compacted fill material. Areas to receive fill and/or
other surface improvements should be processed to a minimum depth of 12
to 24 inches, brought to optimum moisture condition, and recompacted to at
least 90 percent relative compaction (based on ASTM Test Method D1557).
If the length of time between the completion of grading and the construction
of the hotel buildings is longer than six months, we recommend that the
building pads be evaluated by the geotechnical consultant and, if needed,
the finish grade soils on the building pads should be scarified a minimum of
12 inches, moisture-conditioned to optimum moisture-content and
recompacted to a minimum 90 percent relative compaction (based on
ASTM Test Method D1557).
It should be noted that if any building or movement sensitive structures
are proposed for eastern portion of the site within the vicinity of the clay
seam, we recommend further evaluation of the clay seam location be
performed during the fine grading operations to determine the need for
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appropriate mitigation. Based on the current site plans (used as the base
map for our Geotechnical Map, Plate 1), the clay seam is located east of
the proposed improvements.
6.1.2 Mitigation of Cut/Fill Transition Conditions
In order to reduce the potential for differential settlement of the proposed
buildings in areas of cut/fill transitions, we recommend the entire cut portion
of the building pad be overexcavated and replaced with properly compacted
fill.
Where the fill thickness is greater than 5 feet in depth, the overexcavation
of the cut portion of the building pad should be made a minimum of 2 feet
below the lowest planned footing elevation and should extend laterally at
least 10 feet beyond the building perimeter or footprint.
Where the anticipated fill thickness is less than 5 feet in depth, the
overexcavation of the cut portion of the building pad should equal the same
thickness of the maximum fill beneath the pad to a maximum
overexcavation depth of 1 foot below the lowest planned footing elevation.
These overexcavations should also extend laterally at least 10 feet beyond
the building perimeter or footprint. The building pads where these conditions
will occur cannot be determined until the final footing elevations of the
buildings relative to the existing site grades are determined.
In order to minimize perched ground water in the overexcavation, we
recommend that the overexcavation bottom be tilted a minimum of 2-
percent toward the fill side of the building pad. Additional or revised
recommendations may be warranted based on the configuration and size of
the proposed buildings.
6.1.3 Mitigation of High to Verv High Expansive Soils at Finish Grade
Although high to very high expansive soils were not encountered during our
update investigation, theses soils have been encountered in other portion of
Planning Area PA-4 and the adjacent planning areas. Should high to very
high expansive soils be encountered during the future fine grading
operations, we recommend that these soils be removed below the planned
finish grade of the proposed buildings and other movement sensitive
improvements. If these expansive soils are removed, the removal depth
should be a minimum of 3 feet below the lowest planned footing elevation
or until lower expansive sandy soils are encountered. We also recommend
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that the overexcavation bottom be tilted a minimum of 2-percent toward the
fill side of the building pad or toward the street/driveway in order to minimize
perched ground water conditions. The resulting excavation should be
replaced with properly compacted fill possessing a lower expansion
potential. The actual location of the claystones and siltstones at or near
finish grade at the site should be evaluated during the future fine grading
operations.
6.1.4 Excavations
Excavations of the on-site materials may generally be accomplished with
conventional heavy-duty earthwork equipment. It is not anticipated that
blasting will be required or that significant quantities of oversized rock (i.e.
rock with maximum dimensions greater than 8 inches) will be generated
during future grading. However, localized cemented zones within the cut
areas and oversized rock placed within the compacted fill may be
encountered on the site that may require heavy ripping and/or removal. If
oversized rock is encountered, it should be placed in accordance with the
recommendations presented in Appendix D, hauled offsite, or placed in
non-structural or landscape areas. Deep excavations should anticipate well-
cemented sandstone bed across the site. Larger excavations, breakers,
and single-shank ripping may be required in deep utility and in-grading
excavations.
Due to the relatively dense characteristics of the on-site soils, temporary
excavations such as utility trenches in the on-site soils should remain stable
for the period required to construct the utility, provided they are constructed
and monitored in accordance with OSHA requirements.
6.1.5 Fill Placement and Compaction
The on-site soils are generally suitable for use as compacted fill provided
they are free or organic material, debris, and rock fragments larger than
8 inches in maximum dimension. We do not recommend that high or very
high expansive soils be utilized as fill for the building pads or as retaining
wall backfill.
All fill soils should be brought to 2-percent over the optimum moisture
content and compacted in uniform lifts to at least 90 percent relative
compaction based on the laboratory maximum dry density (ASTM Test
Method D1557). The optimum lift thickness required to produce a uniformly
compacted fill will depend on the type and size of compaction equipment
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used. In general, fill should be placed in lifts not exceeding 8 inches in
compacted thickness. Placement and compaction of fill should be
performed in general accordance with Appendix D, the current City of
Carlsbad grading ordinances, sound construction practices, and the
geotechnical recommendations presented herein.
6.2 Foundation Design Considerations
The foundations and slabs for the proposed buildings should be designed in
accordance with structural considerations and the following preliminary
recommendations. These preliminary recommendations assume that the soils
encountered within 5 feet of finish pad grade will have a very low to medium
potential for expansion. If highly expansive soils are encountered within 5 feet of
the proposed finish grade elevations during site grading, these expansive soils
should be removed and replaced with lower expansive soils. If replacement of
the expansive soils is not feasible, additional foundation design will be
necessary.
The proposed buildings may be supported by conventional, continuous or
isolated spread footings. Footings should extend a minimum of 24 inches
beneath the lowest adjacent soil grade. At these depths, footings may be
designed for a maximum allowable bearing pressure of 2,500 pounds per square
foot (psf) if founded in properly compacted fill soils or formational material. An
allowable capacity increase of 500 psf for every 6 inches of additional
embedment may be used to a maximum of 3,500 psf. The allowable pressures
may be increased by one-third when considering loads of short duration such as
wind or seismic forces. The minimum recommended width of footings is 18
inches for continuous footings and 24 inches for square or round footings.
Footings should be designed in accordance with the structural engineer's
requirements and have a minimum reinforcement of four No. 5 reinforcing bars
(two top and two bottom).
The slab-on-grade foundation should be at least 5 inches thick and be reinforced
with No. 4 rebars 18 inches on center or No. 5 rebars at 24 inches on center,
each way. All reinforcing should be placed at mid-height in the slab. Slabs should
be underlain by a 2-inch layer of clean sand (sand equivalent greater than 30),
which is in-turn underlain by a minimum 10-mil plastic sheeting (moisture barrier)
and an additional 2 inches of clean sand. We recommend that control joints be
provided across the slab at appropriate intervals as designed by the project
architect. Some moisture sensitive flooring may require additional measures to
mitigate moisture migration through the slab as designed by the project architect.
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The potential for slab cracking may be reduced by careful control of
water/cement ratios. The contractor should take appropriate curing precautions
during the pouring of concrete in hot weather to minimize cracking of slabs. We
recommend that a slipsheet (or equivalent) be utilized if grouted tile, marble tile,
or other crack-sensitive fioor covering is planned directly on concrete slabs. All
slabs should be designed in accordance with structural considerations. If heavy
vehicle or equipment loading is proposed for the slabs, greater thicknesses and
increased reinforcing may be required as determined by the structural engineer.
6.2.1 Moisture Conditioning
The slab subgrade soils underlying the foundation systems of the
proposed structures should be presoaked in accordance with the
recommendations presented in Table 1 prior to placement of the moisture
barrier and slab concrete. The subgrade soil moisture content should be
checked by a representative of Leighton and Associates prior to slab
construction.
Table 1
Presaturation Recommendations Based on Finish Grade Soil Expansion
Potential
Presaturation
Criteria
Expansion Potential
Presaturation
Criteria
Very Low
(0-20)
Low
(21-50)
Medium
(51-90)
Minimum
Presoaking Depth
(in inches)
6 12 18
Minimum
Recommended
Moisture Content
Near
optimum
moisture
1.2 times
optimum
moisture
1.2 times optimum
moisture
Presoaking or moisture conditioning may be achieved in a number of
ways, but based on our professional experience, we have found that
minimizing the moisture loss of pads that have been completed (by
periodic wetting to keep the upper portion of the pad from drying out)
and/or berming the lot and flooding if for a short period of time (days to a
few weeks) are some of the more efficient ways to meet the presoaking
requirements. If flooding is performed, a couple of days to let the upper
4 -14-Leighton
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portion of the pad dry out and form a crust so equipment can be utilized
should be anticipated.
6.2.2 Foundation Setback
We recommend a minimum horizontal setback distance from the face of
slopes or adjacent retaining walls for ail structural foundations, footings, and
other settlement-sensitive structures as indicated on Table 2. This distance
is measured from the outside bottom edge of the footing, horizontally to the
slope face and is based on the slope height and type of soil. However, the
foundation setback distance may be revised by the geotechnical consultant
on a case-by-case basis if the geotechnical conditions are different than
anticipated.
Table 2
Minimum Foundation Setback from Descending Slope Faces
Slope Height Minimum Recommended Foundation
Setback
Less than 5 feet 5 feet
5 to 15 feet 7 feet
Please note that the soils within the structural setback area possess poor
lateral stability, and improvements (such as retaining walls, sidewalks,
fences, pavements, etc.) constructed within this setback area may be
subject to lateral movement and/or differential settlement. Potential distress
to such improvements may be mitigated by providing a deepened footing or
a pier and grade beam foundation system to support the improvement. The
deepened footing should meet the setback as described above.
6.2.3 Anticipated Settlement
Settlement is anticipated to occur at varying times over the life of the
project. Short-term settlement typically occurs upon application of the
foundation loads and is essentially completed within the construction
period. Long-term (hydroconsolidation) settlement typically occurs in deep
fills upon additional water inflitration into the flII soils (even in properly
compacted fill soils and even with subdrains provided). This settlement
-15-4
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typically occurs over many years. Long-term settlement values and the
affects on the foundations should be evaluated after the site is graded and
the actual fill thicknesses beneath the proposed foundafions known.
However, for preliminary planning purposes, total future settlement is
expected to be order of 1 inch and differential settlement is estimated to
be on the order of 1/2 inch in 50 feet.
6.3 Lateral Earth Pressures
The recommended lateral pressures for the onsite very low to low expansive soil
(expansion index less than 50) or medium expansive soil (expansion index
between 51 and 90) and level or sloping backfill are presented on Table 3. High to
very high expansive soils (having an expansion potenfial greater than 91) should
not be used as backfill soils on the site.
Embedded structural walls should be designed for lateral earth pressures exerted
on them. The magnitude of these pressures depends on the amount of
deformafion that the wall can yield under load. If the wall can yield enough to
mobilize the full shear strength of the soil, it can be designed for "active" pressure.
If the wall cannot yield under the applied load, the shear strength of the soil cannot
be mobilized and the earth pressure will be higher. Such walls should be designed
for "at rest" conditions. If a structure moves toward the soils, the resulting
resistance developed by the soil is the "passive" resistance. The above noted
passive resistance assumes an appropriate setback per Section 6.2.2.
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Table 3
Lateral Earth Pressures
Conditions
Equivalent Fluid Weight (pcf)
Conditions
Very Low to Low Expansive Soils Medium Expansive Soils
Conditions Expansion Index less than 50 Expansion Index between 51
and 90 Conditions
Level 2:1 Slope Level 2:1 Slope
Active 35 55 60 70
At-Rest 55 65 70 80
Passive 350 150 350 150
For design purposes, the recommended equivalent fluid pressure for each case for
walls founded above the static ground water and backfilled with soils of very low to
low expansion potenfial or medium expansion potenfial is provided on Table 3. The
equivalent fluid pressure values assume free-draining condifions. If condifions
other than those assumed above are anticipated, the equivalent fluid pressures
values should be provided on an individual-case basis by the geotechnical
engineer. The geotechnical and structural engineer should evaluate surcharge-
loading effects from the adjacent structures. All retaining wall structures should be
provided with appropriate drainage and appropriately waterproofed. The outlet pipe
should be sloped to drain to a suitable outlet. Typical wall drainage design is
illustrated in Appendix D.
For sliding resistance, the fricfion coefficient of 0.35 may be used at the concrete
and soil interface. In combining the total lateral resistance, the passive pressure or
the frictional resistance should be reduced by 50 percent. Waii footings should be
designed in accordance with structural considerations. The passive resistance
value may be increased by one-third when considering loads of short duration
including wind or seismic loads. The horizontal distance between foundation
elements providing passive resistance should be minimum of three times the depth
of the elements to allow full development of these passive pressures. The total
depth of retained earth for the design of cantilever walls should be the vertical
distance below the ground surface measured at the wall face for stem design or
-17-4
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measured at the heel of the foofing for overturning and sliding. All wall backcuts
should be made in accordance with the current OSHA requirements.
The granular and native backfill soils should be compacted to at least 90 percent
relative compacfion (based on ASTM Test Method D1557). The granular fill should
extend horizontally to a minimum distance equal to one-half the wall height behind
the walls. The walls should be constructed and backfilled as soon as possible after
backcut excavafions. Prolonged exposure of backcut slopes may result in some
localized slope instability.
Foundations for retaining walls in competent formafional soils or properly
compacted fill should be. embedded at least 24 inches below lowest adjacent
grade. At this depth, an allowable bearing capacity of 2,000 psf may be assumed.
6.4 Fences and Freestanding Walls
Footings for freestanding walls should be founded a minimum of 24 inches below
lowest adjacent grade. To reduce the potential for unsightly cracks in freestanding
walls, we recommend inclusion of construcfion joints at a maximum of 15-foot
intervals. This spacing may be altered in accordance with the recommendations of
the structural engineer, based on wall reinforcement details.
Our experience on similar sites in older developments indicates that many walls
on shallow foundations near the top-of-slopes tend to tilt excessively over time
as a result of slope creep. If the effects of slope creep on top-of-slope walls are
not deemed acceptable, one or a combination of the opfions provided in the
following paragraphs should be ufilized in the design of such structures, based
on the desired level of mitigation of creep-related effects on them.
A relatively inexpensive option to address creep related problems in top-of-slope
walls and fences is to allow some degree of creep damage and design the
structures so that filfing or cracking will be less visually obvious, or such that they
may be economically repaired or replaced. If, however, a better degree of creep
mifigafion is desired, the walls and fences may be provided with the deepened
footings to meet the foundation setback criteria, or these structures may be
constructed to accommodate potential movement.
Under certain circumstances, an effecfive solution to minimize the effects of creep
on top-of-slope walls and fences is to support these structures on a pier-and-
grade-beam system. The piers normally consist of minimum 12-inch diameter cast-
in-place caissons spaced at a maximum of 8 feet on center, and connected
together by a minimum 12-inch-thick grade beam at a shallow depth. The piers are
typically at least 10 feet deep for medium or high expansive soil. The steel
4
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603446-001
reinforcement for the system should be designed with consideration of wall/fence
type and loading. Walls or fences aligned essenfially perpendicular to the top of
the slope are normally supported on the pier-and-grade-beam system for at least
that part of the wall that is within 15 feet from the top-of-slope. Caisson support is
recommended for all top-of-slope walls where slopes are greater than 10 feet in
height and/or the soil on and adjacent to the slope consists of high to very high
expansive soils.
6.5 Concrete Flatwork
Some of the on-site soils possess a high expansion potenfial. If possible,
selected grading should be performed to reduce the amount of expansive soil
placed at subgrade elevations in the areas of concrete flatwork. Based on the
anficipated condifions and experience the adjacent commercial development, we
recommend that the upper 24 inches of subgrade soils be pre-saturated to at
least 5 percent above opfimum moisture content prior to placement of concrete
flatwork. For areas previously graded that require reprocessing, we recommend
that the upper 18 inches of subgrade soils be scarified and moisture condifioned
and lightly re-compacted prior to placement of the concrete flatwork. The
reprocessed subgrade soils should be moisture-condifioned to at least 5 percent
above optimum moisture content and compacted to around 90 percent relative
compaction based on American Standard of Testing and Materials (ASTM) Test
Method D1557. Note that these recommendafions are for sidewalks and other
concrete flatwork only and are not applicable to concrete pavement areas
subject to traffic loading.
We also recommend that the sidewalk and/or concrete flatwork be at least 4
inches thick and be reinforced with No. 3 rebars at a minimum spacing of at least
18 inches, each way. In addifion, the sidewalk secfions should be doweled into
the adjacent curbs at a spacing of 36 inches on center and doweled into
adjacent existing sidewalk secfions at a minimum spacing of 18 inches on
center. Note that our representative should also observe and test the compacfion
of the reprocess subgrade soil prior to placement of the reinforcement for new
sidewalk secfions.
6.6 Proposed Swimming Pools
The swimming pools and water elements, if any, should be designed by a
structural engineer to resist the forces lateral earth pressures soils and
differential settlement of the fill. The following items should be taken into
consideration in the design and construction of the swimming pools and water
elements:
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The pool contractor should provide a sufficient level of inspection and control
to assure that approved pool plans and specificafions are implemented
during construction.
Observations and tesfing should be performed by a geotechnical consultant
during pool excavafion and backfill operafions to verify that exposed soil
condifions are consistent with the design assumpfions.
6.6.1 Pool Deck Recommendations
We recommend that the upper 24 inches of subgrade soils be pre-
saturated to at least 5 percent above optimum moisture content prior to
placement of concrete flatwork. For areas previously graded and requiring
reprocessing, we recommend that the upper 18 inches of subgrade soils
be scarified and moisture condifioned and lightly re-compacted prior to
placement of the concrete flatwork. The reprocessed subgrade soils
should be moisture-condifioned to at least 5 percent above optimum
moisture content and compacted to around 90 percent relative
compacfion based on American Standard of Testing and Materials
(ASTM) Test Method D1557.
We also recommend that the pool deck be a minimum of 4-inches thick,
reinforced with No. 3 rebars at 18 inches on center each way. The
perimeter of the decking should be constructed with a perimeter foofing a
minimum of 6 inches wide and deep. The deck should have appropriate
crack control and expansion joints. In general, the construcfion joints
should be a minimum of 5 feet on center (each way) and extend to a
depth of at least 1/3 of the concrete thickness. The joints should not cut
the rebar reinforcement. Special attenfion should be given to ensure that
the joint between the pool decking and pool coping is properly sealed with
a flexible, watertight caulking to prevent water infiltration. The concrete
decking should be sloped to area drains with sufficient gradient to
maintain acfive flow.
4
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6.7 Geochemical Considerations
Geochemical screening of the representative onsite soils was performed as part
of our original study and the results presented in Appendix C. As indicated in
Appendix C, the results of our limited tesfing and our professional knowledge of
similar soils in other portions of the Bressi Ranch project, indicates that concrete
in contact with the on-site soils should be designed in accordance with the
"severe" category. In addition, the onsite soils are anticipated to have a corrosive
environment for buried metal pipes or uncoated metal conduits. Laboratory
testing should be performed on the soils placed at or near finish grade after
completion of site grading to ascertain the actual corrosivity characterisfics.
6.8 Preliminan/ Pavement Design
The preliminary R-Value test results of representative on-site soils range from 5 to
34 (as indicated in Appendix C). These results are similar to the results of the R-
Value testing performed on the adjacent streets (i.e. Gateway Road and
Innovation Way). The appropriate Asphalt Concrete (AC) and Class 2 aggregate
base (AB) pavement secfions will depend on the type of subgrade soil, shear
strength, traffic load, and planned pavement life. Since an evaluation ofthe actual
subgrade soils cannot be made at this fime, we have conservatively assumed an
R-value of 5 and Traffic Indexes (Tl) of 4.0, 5.0, and 6.0. The pavement sections
presented on Table 4 should be used for preliminary planning purposes only.
The pavement sections based on a Tl of 6.0 and 5.0 should be assumed for the
onsite, truck and vehicle driveways, respectively. The pavement secfions for
vehicle parking stalls should be based on a Tl of 4.0. Final pavement designs
should be completed in accordance with the City of Carlsbad design criteria after
R-value tests have been performed on the actual subgrade materials.
4
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603446-001
Table 4
Preliminary Pavement Section Designs
Traffic
Index
Assumed
R-Value
Preliminary Pavement Sections Traffic
Index
Assumed
R-Value AC and Base Section Full Depth AC Section
4.0 5 4 inches AC over 5 inches Class 2
Aggregate Base
6.5 inches AC over native
subgrade soils
5.0 5 4 inches AC over 8 inches Class 2
Aggregate Base
8.0 inches AC over native
subgrade soils
6.0 5 4 inches AC over 12 Inches Class
2 Aggregate Base
10 inches AC over native
subgrade soils
Asphalt Concrete (AC) and Class 2 aggregate base should conform to and be
placed in accordance with the latest revision of California Department of
Transportafion Standard Specificafions. Prior to placing the pavement section,
the subgrade soils should have a relative compacfion of at least 95 percent to a
minimum depth of 12 inches (based on ASTM Test Method D1557). Aggregate
Base should be compacted to a minimum of 95 percent relative compaction
(based on ASTM Test Method D1557) prior to placement of the AC.
For areas subject to unusually heavy truck loading (i.e., trash trucks, delivery
trucks, etc.), we recommend a full depth of Portland Cement Concrete (PCC)
secfion of 7 inches with steel reinforcement (number 4 bars at 18-inch centers,
each way) and crack-control joints at a minimum spacing of 10 feet. We
recommend that sections be as nearly square as possible. A 3,500-psi mix that
produces a 600-psi modulus of rupture should be ufilized. The actual pavement
design should also be in accordance with City of Carlsbad and ACI design
criteria.
If pavement areas are adjacent to heavily watered landscaping areas, we
recommend some measures of moisture control be taken to prevent the subgrade
soils from becoming saturated. It is recommended that the concrete curbing,
separating the landscaping area from the pavement, extend below the aggregate
base to help seal the ends of the secfions where heavy landscape watering may
have access to the aggregate base. Concrete swales should be designed if
asphalt pavement is used for drainage of surface waters.
-22-4
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6.9 Control of Surface Water and Drainage
Regarding Low Impact Development (LID) measures, we are of the opinion that
infiltration basins, and other onsite storm water retention and infiltration systems
can potentially create adverse perched ground water condifions. In addition, the
existing onsite soils are anficipated to provide relafively low or minimal infiltration
rates for the surface water. Therefore, given the site geologic condifions, relatively
low infiltration rate, and project type, infiltration type LID measures are not
considered to be appropriate for this site and project.
Surface drainage should be carefully taken into consideration during precise
grading, landscaping, and building construcfion. Positive drainage (e.g., roof
gutters, downspouts, area drain, etc.) should be provided to direct surface water
away from structures and towards the street or suitable drainage devices. Ponding
of water adjacent to structures should be avoided; roof gutters, downspouts, and
area drains should be aligned so as to transport surface water to a minimum
distance of 5 feet away from structures. The performance of structural foundations
is dependent upon maintaining adequate surface drainage away from structures.
Water should be transported off the site in approved drainage devices or
unobstructed swales. We recommend that the minimum flow gradient for the
drainage be 1-percent for area drains and paved drainage swales; and 2-percent
for unpaved drainage swales. We recommend that where structures will be
located within 5 feet of a proposed drainage swale, the surface drainage
adjacent to the structures be accomplished with a gradient of at least 3-1/2
percent away from the structure for a minimum horizontal distance of 3 feet.
Drainage should be further maintained by a swale or drainage path at a gradient
of at least 1-percent for area drains and paved drainage swales and 2-percent for
unpaved drainage swales to a suitable collection device (i.e. area drain, street
gutter, etc.). We also recommend that structural footings within 4 feet of the
drainage swale flowline be deepened so that the bottom of the footing is at least
12 inches below the flow-line ofthe drainage swale. In places where the prospect
of maintaining the minimum recommended gradient for the drainage swales and
the construction of addifional area drains is not feasible, provisions for specific
recommendafions may be necessary, oufiining the importance of maintaining
positive drainage.
The impact of heavy irrigation or inadequate runoff gradient can create perched
water condifions, resulting in seepage or shallow groundwater condifions where
previously none existed. Maintaining adequate surface drainage and controlled
irrigation will significantly reduce the potential for nuisance-type moisture problems.
To reduce differential earth movements (such as heaving and shrinkage due to the
change in moisture content of foundafion soils, which may cause distress to a
4
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603446-001
structure or improvement), the moisture content of the soils surrounding the
structure should be kept as relafively constant as possible.
All area drain inlets should be maintained and kept clear of debris in order to
function properly. Reroufing of site drainage patterns and/or installation of area
drains should be performed, if necessary. A qualified civil engineer or a landscape
architect should be consulted prior to rerouting of drainage.
6.10 Slope Maintenance Guidelines
It is the responsibility of the owner to maintain the slopes, including adequate
planting, proper irrigation and maintenance, and repair of faulty irrigafion
systems. To reduce the potenfial for erosion and slumping of graded slopes, all
slopes should be planted with ground cover, shrubs, and plants that develop
dense, deep root structures and require minimal irrigation. Slope planfing should
be carried out as soon as pracfical upon complefion of grading. Surface-water
runoff and standing water at the top-of-slopes should be avoided.
Oversteepening of slopes should be avoided during construcfion activities and
landscaping. Maintenance of proper lot drainage, undertaking of property
improvements in accordance with sound engineering pracfices, and proper
maintenance of vegetafion, including regular slope irrigation, should be
performed. Slope irrigafion sprinklers should be adjusted to provide maximum
uniform coverage with minimal of water usage and overlap. OvenA/atering and
consequent runoff and ground saturafion should be avoided. If automafic
sprinklers systems are installed, their use must be adjusted to account for rainfall
condifions.
Trenches excavated on a slope face for any purpose should be properly
backfilled and compacted in order to obtain a minimum of 90 percent relative
compacfion, in accordance with ASTM Test Method D1557. Observafion/tesfing
and acceptance by the geotechnical consultant during trench backfill are
recommended. A rodent-control program should be established and maintained.
Prior to planting, recently graded slopes should be temporarily protected against
erosion resulfing from rainfall, by the implementing slope protection measures
such as polymer covering, jute mesh, etc.
4
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603446-001
6.11 Landscaping and Post-Construcfion
Landscaping and post-construction practices carried out by the owner(s) and their
representative bodies exert significant influences on the integrity of structures
founded on expansive soils. Improper landscaping and post-construction pracfices,
which are beyond the control of the geotechnical engineer, are frequently the
primary cause of distress to these structures. Recommendafions for proper
landscaping and post-construcfion practices are provided in the following
paragraphs within this section. Adhering to these recommendafions will help in
minimizing distress due to expansive soils, and in ensuring that such effects are
limited to cosmetic damages, without compromising the overall integrity of
structures.
Initial landscaping should be done on all sides adjacent to the foundation of a
structure, and adequate measures should be taken to ensure drainage of water
away from the foundation. If larger, shade providing trees are desired, such trees
should be planted away from structures (at a minimum distance equal to half the
mature height of the tree) in order to prevent penetrafion of the tree roots beneath
the foundation of the structure.
Locafing planters adjacent to buildings or structures should be avoided as much as
possible. If planters are utilized in these locafions, they should be properly
designed so as to prevent fluctuations in the moisture content of subgrade soils.
Planfing areas at grade should be provided with appropriate positive drainage.
Wherever possible, exposed soil areas should be above paved grades. Planters
should not be depressed below adjacent paved grades unless provisions for
drainage, such as catch basins and drains, are made. Adequate drainage
gradients, devices, and curbing should be provided to prevent runoff from adjacent
pavement or walks into planfing areas.
Watering should be done in a uniform, systematic manner as equally as possible
on all sides of the foundafion, to keep the soil moist Irrigation methods should
promote uniformity of moisture in planters and beneath adjacent concrete fiatwork.
Ovenwatering and undenwatering of landscape areas must be avoided. Areas of
soil that do no have ground cover may require more moisture, as they are more
susceptible to evaporation. Ponding or trapping of water in localized areas
adjacent to the foundations can cause differential moisture levels in subsurface
soils and should, therefore, not be allowed. Trees located within a distance of 20
feet of foundations would require more water in periods of extreme drought, and in
some cases, a root injection system may be required to maintain moisture
equilibrium. During extreme hot and dry periods, close observafions should be
carried out around foundations to ensure that adequate watering is being
undertaken to prevent soil from separafing or pulling back from the foundafions.
4
'^^ Leighton
603446-001
6.12 Construction Observation and Testing
Construction observation and tesfing should be performed by the geotechnical
consultant during the remaining grading operafions, future excavations and
foundation or retaining wall construction on the graded portions of the site.
Additionally, foofing excavafions should be observed and moisture determination
tests of subgrade soils should be performed by the geotechnical consultant prior to
the pouring of concrete. Foundation design plans shouid also be reviewed by the
geotechnical consultant prior to excavations.
4
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7.0 LIMITATIONS
The conclusions and recommendafions presented in this report are based in part upon
data that were obtained from a limited number of observafions, site visits, excavafions,
samples, and tests. Such informafion is by necessity incomplete. The nature of many
sites is such that differing geotechnical or geological condifions can occur within small
distances and under varying climatic conditions. Changes in subsurface conditions can
and do occur over fime. Therefore, the findings, conclusions, and recommendafions
presented in this report can be relied upon only if Leighton has the opportunity to
observe the subsurface condifions during grading and construcfion of the project, in
order to confirm that our preliminary findings are representative for the site.
4
Leighton
FIGURE
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LEGEND
Afo AimnciAL nu. PLACED DURING THE BRESSI RANCH ROUGH GRADING. 2004
Tw TERTIARY-AGED SANTIAGO FORMATION, CIRCLED WHERE BURIED
Af ARTinCIAL HLL PLACED DURING CURRENT FINE GRADING OPERATONS. 2007
T-25 SB APPROXIMATE TEST PfT LOCATION. 2006
_4,— A . . T APPROXIMATE LOCATION OF CLAY SEAM. DOHED WHERE BURIED. QUERIED
WERE UNCERTAIN
. .7. APPROXIMATE GEOLOGIC CONTACT. DOHED WHERE BURIED. QUERIED WHERE
UNCERTAIN
1LJJ--LL- APPROXIMATE UMITS OF FILL, 2007
APPROXIMATE LOCATION OF FIELD DENSITY TEST (CF=COMPACTED FIU.
FG=FINICH GRADE. SF=SLOPE FACE). 2007
riiSl APPROXIMATE ELEVATION OF REMOVAL BOHOM. 2007
Y////\ APPROXIMATE LOCATION OF FIU SLOPE KEY. 2007
CF-33 • r398 I .
. - CF-36.A -i^-'
Af •
Refefence Site Pl»i. Holiday Inn Stay Brdge SMta Za-vaeA. By Pnina Grouo ShMl AS^IOl, d*«l4-12-12
PLATE 1 GEOTECHNICAL MAP
BRESSI RANCH HOTELS
CARLSBAO. CALIFORNIA
Leignton
GEOTECHNICAL MAP
BRESSI RANCH HOTELS
CARLSBAO. CALIFORNIA
Leignton
Proj: 603446-001 Eng/Geol: WDO/MDJ
Leignton Scale: rsSff Date: 05/2012
APPENDIX A
REFERENCES
603446-001
APPENDIX A
REFERENCES
California Division of Mines and Geology (CDMG), 1995, Landslide Hazards in the
Northern Part of the San Diego Metropolitan Area, San Diego County, California,
Open-File Report 95-04.
, 1996, Probabilistic Seismic Hazard Assessment for the State of California,
Open-File Report, 96-08.
, 1998, Maps of Known Active Fault Near-Source Zones in California and
Adjacent Portions of Nevada, dated February 1998.
California Building Standards Commission (CBSC), 2010, California Building Code,
Volume I and Volume II.
California Geological Survey, 2003, The Revised California Probabilistic Seismic Hazard
Assessment Maps, June 2003.
Hannan, D., 1975, Faulfing in the Oceanside, Carlsbad and Vista Areas, Northern San
Diego County, California jn Ross, A. and Dowlens, R.J., eds.. Studies on the
Geology of Camp Pendleton and Western San Diego County, California: San
Diego Associafion of Geologists, pp. 56-59.
Hart, E.W. and Bryant W.A., 2007, Fault-Rupture Hazard Zones in California, Alquist-
Priolo Special Studies Zones Act of 1972 with Index to Special Studies Zones
Maps: Department of Conservation, Division of Mines and Geology, Special
Publication 42.
Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, with Locafions
and Ages of Recent Volcanic Eruptions: California Division of Mines and Geology,
California Geologic Data Map Series, Map No. 6, Scale 1:750,000.
Kennedy, M.P. and Welday, E.E., 1980, Character and Recency of Faulfing Offshore
Metropolitan San Diego, California: California Division of Mines and Geology
Map Sheet 40.
A-l
603446-001
APPENDIX A (confinued)
Leighton and Associates, Inc., 1997, Preliminary Geotechnical Investigation, Bressi
Ranch, Carlsbad, California, Project No. 4971009-002, dated July 29, 1997.
, 2001, Supplemental Geotechnical Investigation for Mass Grading, Bressi
Ranch, Carlsbad, California, Project No. 971009-0015, dated March 14, 2001.
, 2002, Geotechnical Conclusions Concerning the Mass Grading
Recommendafions Relative to Proposed Fine Grading and Review of the 40-
Scale Tentative Maps, Bressi Ranch, Carlsbad, California, Project No. 971009-
007, dated September 12, 2002.
, 2003a, Geotechnical Grading Plan Review of the Mass Grading Plans,
Bressi Ranch, Carlsbad, California, Project No. 971009-007, dated January 17,
2003.
, 2003b, Preliminary Residential and Commercial Foundafion Design
Recommendafions, Bressi Ranch, Carlsbad, California, Project No. 971009-007,
dated February 5, 2003.
, 2004a, Summary of the As-Graded Geotechnical Conditions and Partial
Complefion of Rough and Fine Grading, Planning Areas PA-1 Through PA-5,
Bressi Ranch, Carlsbad, California, Project No. 971009-014, dated January 20,
2004.
, 2004b, Geotechnical Maps, Planning Areas PA-4 and PA-5, Bressi Ranch,
Carlsbad, California, Project No. 971009-014, dated April 15, 2004.
, 2004c, As-Graded Report of Mass Grading, Planning Areas PA-4 and PA-
5, Innovafion Way and a Portion of Gateway Road, Carlsbad Tract No. 00-06,
Bressi Ranch, Carlsbad, California, Project No. 971009-014, dated May 25,
2004.
, 2004d, Addendum to the As-Graded Reports of Mass Grading Concerning
the Completion of Settlement Monitoring, Planning Areas PA-1 through PA-5,
Bressi Ranch, Carlsbad, California, Project No. 971009-014, dated October 11,
2004.
, 2006, Geotechnical Update Invesfigafion, Lots 24 through 28 of Planning
Area PA-4, Bressi Ranch, Carlsbad, California, Project No. 971009-041, dated
February 3, 2006
A-2
603446-001
APPENDIX A (confinued)
Leighton and Associates, Inc., 2007, As-Grade Report of Fine Grading, The Towers at
Bressi Ranch, Lots 24 through 28 of Planning Area PA-4, Carlsbad Tract No. CT
02-15, Carlsbad, California, Project No. 971009-045, dated February 23, 2007.
Prime Group Construcfion, 2012, Conceptual Site Plan, Holiday Inn / Staybidge Suites
Site Carlsbad, California, dated April 12, 2012.
A-3
APPENDIX B
LEIGHTON 2006 TEST PIT LOGS
LOG OF TRENCH: T-1
Proiect Name: Rvan/Bressi PA-4 T naoed hv: ATR
Proiect Number! Q7innQ.n41 PWatinn- ^X/i' ENGINEERING PROPERTIES
Equipment: Rarkhnp 4inn.CAX. , Location/Grid:—tmRnilHing A Equipment: Rarkhnp 4inn.CAX. , Location/Grid:—tmRnilHing A
GEOLOGIC
ATTITUDES DATE: 12/15/05 DESCRIPTION: GEOLOGIC
UNIT USCS
Sample
No.
Moisture
(%)
Density
(pcO ARTIFICIAL FILL Af CH B-1
A @ O'-l .5': Sandy CLAY: Olive-brown, moist, medium dense; medium to
high plasticity
TERTIARY SANTIAGO FORMATION
Tsa SC
0'-1.5'
B @ 1.5'-2.8': Slightly clayey SANDSTONE: Light olive, moist, dense;
calcium carbonate blebs throughout, oxidized zones, massive
C @2.8'-4': CLAYSTONE: Olive, moist, hard; oxidized zones, medium
plasticity
D @ 4'-5.4': Fine to medium grained slightly clayey SANDSTONE: Light
olive, moist, dense; calcium carbonate blebs throughout, oxidized zones,
massive
CL
SC
GRAPHICAL REPRESENTATION: W WaU SCALE: r'=5' SURFACE SLOPE: 0° TREND: NS
B A
-_-^-c
Total Depth = 5.4 Feet
No Ground Water Encountered
Backfilled: 12/15/05
LOG OF TRENCH: T-?
Project Name: Ryan/Rressi PA-4
Project Number: Q7l 000-041
Equipment: Rarkhr^. 4^01^ TAT
Logged by:
Elevation:_
.AIB-
GEOLOGIC
ATTITUDES
Location/Grid: NWR..iM;ngf>
DATE: 12/15/05 DESCRIPTION:
ARTIFICIAL FILL
A @ 0'-5': Slightly clayey SAND: Light gray-brown, moist, loose to medium
dense; rootlets present
TERTIARY SANTIAGO FORMATION
B @ .5'-3.9': Sandy CLAYSTONE/SILTSTONE: Olive, moist, firm to hard;
oxidized blebs, grades to sandier at base of unit, medium plasticity
C @ 3.9'-5': Fine grained slightly clayey SANDSTONE: Light olive moist,
dense; yellow staining
GEOLOGIC
UNIT
Af
Tsa
GRAPHICAL REPRESENTATION: W Wall
ENGINEERING PROPERTIES
USCS
SC
CL/
ML
SC
SCALE: 1"=5' SURFACE SLOPE: 0°
A
Sample
No.
Moisture Density
(pcf)
TREND: NS
Total Depth = 5 Feet
No Ground Water Encountered
Backfilled: 12/15/05
LOG OF TRENCH:
Project Name:, Ryan/Bresf^i PA-4
Project Number: Q7lonQ-04i
Equipment: Rg^i-hn^A^onrAT
Logged by:.
Elevation:_
.AIE.
GEOLOGIC
ATTITUDES
Location/Grid: NF. RnilHing F
DATE: 12/15/05 DESCRIPTION:
ARTIFICIAL FILL
A @ 0'-.5': Slightly clayey SAND: Light olive, moist, loose to medium dense;
rootlets present
TERTIARY SANTIAGO FORMATION
B @ .5'-5': Silty CLAYSTONE: Olive, moist, hard; oxidized zones and
gypsum present
GEOLOGIC
UNIT
Af
Tsa
ENGINEERING PROPERTIES
USCS
SC
CL
Sample
No.
GRAPHICAL REPRESENTATION: W Wall SCALE: r'=5' SURFACE SLOPE:
Moisture
(%)
Density
(pcf)
TREND: NS
A
-> -
Total Depth = 5 F(
No Ground Water
Backfilled: 12/15
set
Encountered
'05
LOG OF TRENCH: T-4
Project Name: Ryan/Bressi PA-4 1 .ngged hy A.m
Project Number: 971009-041 Flevation: ^X4' ENGINEERING PROPERTIES
Equipment: Rarkhnp.41flD CAT location/Grid: Equipment: Rarkhnp.41flD CAT location/Grid: SW R.nlHma A
GEOLOGIC
ATTITUDES DATE: 12/15/05 DESCRIPTION: GEOLOGIC
UNIT USCS
Sample
No.
Moisture
(%)
Density
(pcf)
ARTIFICIAL FILL Af SM
A @ 0-.5': Silty SAND: Light brown, moist, loose to medium dense
TERTIARY SANTIAGO FORMATION Tsa ML
B @ .5'-2.5': Clayey SILTSTONE: Olive, moist, dense; oxidized and calcium
carbonate blebs throughout, blocky
C @ 2.5'-4.5': Silty CLAYSTONE: Olive, moist, hard; massive, oxidized blebs CL
D @ 4.5'-5': Fine-grained slightly clayey SANDSTONE: Light gray, moist,
dense; oxidized blebs, massive
SC
GRAPHICAL REPRESENTATION: W Wall SCALE: 1"=5' SURFACE SLOPE: 0°
A
4-
C
D
TREND: NS
Total Depth = 5 Feet
No Ground Water Encountered
Backfilled: 12/15/05
LOG OF TRENCH: T.5
Project Name:, Ryan/Rres.«ii PA-4
Project Number:
Equipment:
971009.041
Logged by:.
Elevation:—
-AIB_
187'
RarVhn^4^0r>rAT
GEOLOGIC
ATTITUDES
Location/Grid: sw RnilHmg r
DATE: 12/15/05 DESCRIPTION:
ARTIFICIAL FILL
A @ 0'-.5': Silty SAND: Light brown, moist, loose to medium dense; rootlets
present
TERTIARY SANTIAGO FORMATION
B @ .5'-5': Clayey SILSTONE: Olive, moist, dense; oxidized blebs, blocky
GEOLOGIC
UNIT
Af
T.sa
ENGINEERING PROPERTIES
USCS
SM
ML
Sample
No.
B-1
@
.5'-5'
Moisture
(%)
Density
(pcf)
GRAPHICAL REPRESENTATION: W Wall SCALE: 1"=5' SURFACE SLOPE: 0° TREND: NS
-A
B
Total Depth = 5 Feet
No Ground Water Encountered
Backfilled: 12/15/05
LOG OF TRENCH: T-ft
Project Name:. Ryan/Bressi PA-4
Project Number: 971009-041
Equipment: Rar.khnp 4100 CAT
Logged by:.
E!evation:_
AJB
194'
Location/Grid: sWRiniHmgP
GEOLOGIC
ATTITUDES DATE: 12/15/205 DESCRIPTION: GEOLOGIC
UNIT
ENGINEERING PROPERTIES
USCS
Sample
No.
Moisture
(%)
Density
(pcf)
ARTIFICIAL FILL
A
Af SM
@ 0'-.5': Silty SAND: Light gray, moist, loose to medium dense; rootlets
present
TERTIARY SANTIAGO FORMATION
B @ .5'-4.5': Fine to medium grained silty SANDSTONE: Light gray, moist,
dense to very dense; oxidized blebs, few laminated beds
Tsa SM
GRAPHICAL REPRESENTATION: W Wall SCALE: 1"=5' SURFACE SLOPE: 0° TREND: NS
A
-i-
B
Total Depth = 4.5 Feet
No Ground Water Encountered
Backfilled: 12/15/05
LOG OF TRENCH: T-7
Project Name: Ryan/Rres.si PA-4
Project Number: 97100Q-041
Equipment: Rarkhnp. 4100 CAT
Logged by:,
Elevation:—
AJB
198'
Location/Grid: SF Rnilding F
GEOLOGIC
ATTITUDES DATE: 12/15/05 DESCRIPTION: GEOLOGIC
UNIT
ENGINEERING PROPERTIES
Sample
USCS No.
Moisture
'0/
Density
(pcQ
ARTIFICIAL FILL
A @0'-.3': Silty SAND: Light brown, moist, firm; rootlets present
TERTIARY SANTIAGO FORMATION
B @ .3'-4.7': Silty CLAYSTONE: Dark brown, moist, hard; yellow staining
and gypsum throughout
C @4.7'-5': Silty CLAYSTONE: Dark gray-brown, moist, hard; gypsum
present
Af
Tsa
SM
CL
GRAPHICAL REPRESENTATION: W Wall SCALE: 1"=5' SURFACE SLOPE: 0°
B-1
@
.3'-4.7'
TREND: NS
•
A
-B--
/
C Total Depth = 5 Feet
No Ground Water Encountered
Backfilled: 12/15/05
APPENDIX C
LEIGHTON 2006
LABORATORY TESTING PROCEDURES AND TEST RESULTS
603446-001
APPENDIX C
Laboratory Tesfing Procedures and Test Results
Expansion Index Tests: The expansion potential of selected materials was evaluated by
the Expansion Index Test, ASTM Standard D4829. Specimens are molded under a given
compactive energy to approximately the optimum moisture content and approximately 50
percent saturation. The prepared 1-inch thick by 4-inch diameter specimens are loaded to
an equivalent 144 psf surcharge and are inundated with water unfil volumetric equilibrium
is reached. The results of these tests are presented in the table below:
Sample Location Sample Descripfion Expansion
Index
Expansion
Potential
Test Pit T-1 Brown fat CLAY 67 Medium
Test Pit T-7 Brown lean sandy CLAY 26 Low
Minimum Resistivity and pH Tests: Minimum resistivity and pH tests were performed in
general accordance with Caltrans Test Method CT643 for Steel or CT532 for concrete
and standard geochemical methods. The results are presented in the table below:
Sample Locafion Sample Descripfion pH
Minimum
Resistivity (ohms-
cm)
Test Pit T-1 Brown fat CLAY 7.9 440
Chloride Content: Chloride content was tested in accordance with Caltrans Test Method
CT422. The results are presented below:
Sample Locafion Chloride Content, ppm Chloride Attack
Potenfial*
Test Pit T-1 240 Threshold
'Per City of San Diego Program Guidelines for Design Consultant, 1992.
c-1
603446-001
APPENDIX 0 (Confinued)
Soluble Sulfates: The soluble sulfate contents of selected samples were determined by
standard geochemical methods (Caltrans Test Method CT417). The test results are
presented in the table below:
Sample Locafion Sulfate Content (%) Potenfial Degree
of Sulfate Attack
Test Pit T-7 0.20 Severe
"R"-Value: The resistance "R'-value was determined by the California Materials Method
CT301 for base, subbase, and basement soils. The samples were prepared and
exudation pressure and "R"-value determined. The graphically determined "R"-value at
exudation pressure of 300 psi is reported.
Sample Location Sample Descripfion R-Value
Test Pit T-1 Brown fat CLAY 5
C-2
APPENDIX D
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
1.0 General
1.1 Intent
These General Earthwork and Grading Specifications are for the grading and
earthwork shown on the approved grading plan(s) and/or indicated in the
geotechnical report(s). These Specifications are a part of the recommendations
contained in the geotechnical report(s). In case of conflict, the specific
recommendations in the geotechnical report shall supersede these more general
Specifications. Observations of the earthwork by the project Geotechnical
Consultant during the course of grading may result in new or revised
recommendations that could supersede these specifications or the
recommendations in the geotechnical report(s).
1.2 The Geotechnical Consultant of Record
Prior to commencement of work, the owner shall employ the Geotechnical
Consultant of Record (Geotechnical Consultant). The Geotechnical Consultants
shall be responsible for reviewing the approved geotechnical report(s) and
accepting the adequacy ofthe preliminary geotechnical findings, conclusions, and
recommendations prior to the commencement of the grading.
Prior to commencement of grading, the Geotechnical Consultant shall review the
"work plan" prepared by the Earthwork Contractor (Contractor) and schedule
sufficient persormel to perform the appropriate level of observation, mapping, and
compaction testing.
During the grading and earthwork operations, the Geotechnical Consultant shall
observe, map, and docvmient the subsurface exposures to verify the geotechnical
design assumptions. If the observed conditions are found to be significantly
different than the interpreted assumptions during the design phase, the
Geotechnical Consultant shall inform the owner, recommend appropriate changes
in design to accommodate the observed conditions, and notify the review agency
where required. Subsurface areas to be geotechnically observed, mapped,
elevations recorded, and/or tested include natural ground after it has been cleared
for receiving fill but before fill is placed, bottoms of all "remedial removal" areas,
all key bottoms, and benches made on sloping ground to receive fill.
The Geotechnical Consultant shall observe the moisture-conditioning and
processing of the subgrade and fill materials and perform relative compaction
testing of fill to determine the attained level of compaction. The Geotechnical
Consultant shall provide the test results to the owner and the Contractor on a
routine and frequent basis.
-1-
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
1.3 The Earthwork Contractor
The Earthwork Contractor (Contractor) shall be qualified, experienced, and
knowledgeable in earthwork logistics, preparation and processing of ground to
receive fill, moisture-conditioning and processing of fill, and compacting fill.
The Contractor shall review and accept the plans, geotechnical report(s), and
these Specifications prior to commencement of grading. The Contractor shall be
solely responsible for performing the grading in accordance with the plans and
specifications.
The Contractor shall prepare and submit to the ovmer and the Geotechnical
Consultant a work plan that indicates the sequence of earthwork grading, the
number of "spreads" of work and the estimated quantities of daily earthwork
contemplated for the site prior to commencement of grading. The Contractor
shall inform the ovraer and the Geotechnical Consultant of changes in work
schedules and updates to the work plan at least 24 hours in advance of such
changes so that appropriate observations and tests can be plarmed and
accomplished. The Contractor shall not assume that the Geotechnical Consultant
is aware of all grading operations.
The Contractor shall have the sole responsibility to provide adequate equipment
and methods to accomplish the earthwork in accordance with the applicable
grading codes and agency ordinances, these Specifications, and the
recommendations in the approved geotechnical report(s) and grading plan(s). If,
in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as
unsuitable soil, improper moisture condition, inadequate compaction, insufficient
buttress key size, adverse weather, etc., are resulting in a quality of work less than
required in these specifications, the Geotechnical Consultant shall reject the work
and may recommend to the ovraer that construction be stopped until the
conditions are rectified.
2.0 Preparation of Areas to be Filled
2.1 Clearing and Grubbing
Vegetation, such as brush, grass, roots, and other deleterious material shall be
sufficiently removed and properly disposed of in a method acceptable to the
owner, goveming agencies, and the Geotechnical Consultant.
The Geotechnical Consultant shall evaluate the extent of these removals
depending on specific site conditions. Earth fill material shall not contain more
than 1 percent of organic materials (by volume). No fill lift shall contain more
than 5 percent of organic matter. Nesting of the organic materials shall not be
allowed.
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
If potentially hazardous materials are encountered, the Contractor shall stop work
in the affected area, and a hazardous material specialist shall be informed
immediately for proper evaluation and handling of these materials prior to
continuing to work in that area.
As presently defined by the State of Califomia, most refined petroleum products
(gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents
that are considered to be hazardous waste. As such, the indiscriminate dumping
or spillage of these fiuids onto the ground may constitute a misdemeanor,
punishable by fines and/or imprisormient, and shall not be allowed.
2.2 Processing
Existing ground that has been declared satisfactory for support of fill by the
Geotechnical Consultant shall be scarified to a minimum depth of 6 inches.
Existing ground that is not satisfactory shall be overexcavated as specified in the
following section. Scarification shall continue until soils are broken down and
free of large clay lumps or clods and the working surface is reasonably uniform,
flat, and free of uneven features that would inhibit uniform compaction.
2.3 Overexcavation
In addition to removals and overexcavations recommended in the approved
geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy,
organic-rich, highly fractured or otherwise unsuitable ground shall be
overexcavated to competent ground as evaluated by the Geotechnical Consultant
during grading.
2.4 Benching
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to
vertical units), the ground shall be stepped or benched. Please see the Standard
Details for a graphic illustration. The lowest bench or key shall be a minimum of
15 feet wide and at least 2 feet deep, into competent material as evaluated by the
Geotechnical Consultant. Other benches shall be excavated a minimum height of
4 feet into competent material or as otherwise recommended by the Geotechnical
Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or
otherwise overexcavated to provide a flat subgrade for the fill.
2.5 Evaluation/Acceptance of Fill Areas
All areas to receive fill, including removal and processed areas, key bottoms, and
benches, shall be observed, mapped, elevations recorded, and/or tested prior to
being accepted by the Geotechnical Consultant as suitable to receive fill. The
Contractor shall obtain a written acceptance from the Geotechnical Consultant
-3-
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
prior to fill placement. A licensed surveyor shall provide the survey control for
determining elevations of processed areas, keys, and benches.
3.0 Fill Material
3.1 General
Material to be used as fill shall be essentially free of organic matter and other
deleterious substances evaluated and accepted by the Geotechnical Consultant
prior to placement. Soils of poor quality, such as those with unacceptable
gradation, high expansion potential, or low strength shall be placed in areas
acceptable to the Geotechnical Consultant or mixed with other soils to achieve
satisfactory fill material.
3.2 Oversize
Oversize material defined as rock, or other irreducible material vsdth a maximum
dimension greater than 8 inches, shall not be buried or placed in fill unless
location, materials, and placement methods are specifically accepted by the
Geotechnical Consultant. Placement operations shall be such that nesting of
oversized material does not occur and such that oversize material is completely
surrounded by compacted or densified fill. Oversize material shall not be placed
within 10 vertical feet of finish grade or within 2 feet of future utilities or
underground construction.
3.3 Import
If importing of fill material is required for grading, proposed import material shall
meet the requirements of Section 3.1. The potential import source shall be given
to the Geotechnical Consultant at least 48 hours (2 working days) before
importing begins so that its suitability can be determined and appropriate tests
performed.
4.0 Fill Placement and Compaction
4.1 Fill Layers
Approved fill material shall be placed in areas prepared to receive fill (per
Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness.
The Geotechnical Consultant may accept thicker layers if testing indicates the
grading procedures can adequately compact the thicker layers. Each layer shall
be spread evenly and mixed thoroughly to attain relative uniformity of material
and moisture throughout.
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specificafions
4.2 Fill Moisture Conditioning
Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to
attain a relatively uniform moisture content at or slightly over optimum.
Maximum density and optimum soil moisture content tests shall be performed in
accordance with the American Society of Testing and Materials (ASTM Test
Method D1557).
4.3 Compaction of Fill
After each layer has been moisture-conditioned, mixed, and evenly spread, it shall
be uniformly compacted to not less than 90 percent of maximum dry density
(ASTM Test Method D1557). Compaction equipment shall be adequately sized
and be either specifically designed for soil compaction or of proven reliability to
efficiently achieve the specified level of compaction with uniformity.
4.4 Compaction of Fill Slopes
In addition to normal compaction procedures specified above, compaction of
slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at
increments of 3 to 4 feet in fill elevation, or by other methods producing
satisfactory results acceptable to the Geotechnical Consultant. Upon completion
of grading, relative compaction of the fill, out to the slope face, shall be at least
90 percent of maximum density per ASTM Test Method D1557.
4.5 Compaction Testing
Field-tests for moisture content and relative compaction of the fill soils shall be
performed by the Geotechnical Consultant. Location and frequency of tests shall
be at the Consultant's discretion based on field conditions encountered.
Compaction test locations will not necessarily be selected on a random basis.
Test locations shall be selected to verify adequacy of compaction levels in areas
that are judged to be prone to inadequate compaction (such as close to slope faces
and at the fill/bedrock benches).
4.6 Frequency of Compaction Testing
Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or
1,000 cubic yards of compacted fill soils embankment. In addition, as a
guideline, at least one test shall be taken on slope faces for each 5,000 square feet
of slope face and/or each 10 feet of vertical height of slope. The Contractor shall
assure that fill constmction is such that the testing schedule can be accomplished
by the Geotechnical Consultant. The Contractor shall stop or slow down the
earthwork constmction if these minimxmi standards are not met.
-5-
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
4.7 Compaction Test Locations
The Geotechnical Consultant shall document the approximate elevation and
horizontal coordinates of each test location. The Contractor shall coordinate with
the project surveyor to assure that sufficient grade st8ikes are established so that
the Geotechnical Consultant can determine the test locations with sufficient
acciu-acy. At a minimum, two grade stakes within a horizontal distance of 100
feet and vertically less than 5 feet apart from potential test locations shall be
provided.
5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical
report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may
recorrunend additional subdrains and/or changes in subdrain extent, location, grade, or
material depending on conditions encoimtered during grading. All subdrains shall be
surveyed by a land surveyor/civil engineer for line and grade after installation and prior
to burial. Sufficient time should be allowed by the Contractor for these surveys.
6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the
Geotechnical Consultant during grading. Remedial removal depths shovra on
geotechnical plans are estimates only. The actual extent of removal shall be determined
by the Geotechnical Consultant based on the field evaluation of exposed conditions
during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope
shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement
of materials for constmction of the fill portion of the slope, unless otherwise
recommended by the Geotechnical Consultant.
7.0 Trench Backfills
7.1 Safetv
The Contractor shall follow all OSHA and Cal/OSHA requirements for safety of
trench excavations.
-6-
LEIGHTON CONSULTING, INC.
General Earthwork and Grading Specifications
7.2 Bedding and Backfill
All bedding and backfill of utility trenches shall be performed in accordance with
the applicable provisions of Standard Specifications of Public Works
Constmction. Bedding material shall have a Sand Equivalent greater than 30
(SE>30). The bedding shall be placed to 1 foot over the top of the conduit and
densified. Backfill shall be placed and densified to a minimum of 90 percent of
relative compaction fi'om 1 foot above the top of the conduit to the surface.
The Geotechnical Consultant shall test the trench backfill for relative compaction.
At least one test should be made for every 300 feet of trench and 2 feet of fill.
7.3 Lift Thickness
Lift thickness of trench backfill shall not exceed those allowed in the Standard
Specifications of Public Works Constmction unless the Contractor can
demonstrate to the Geotechnical Consultant that the fill lift can be compacted to
the minimum relative compaction by his alternative equipment and method.
7.4 Observation and Testing
The densification of the bedding around the conduits shall be observed by the
Geotechnical Consultant.
-7-
RLL SLOPE
PROJECTED PLANE 1:1
(HORIZONTAL: VERTICAL)
MAXIMUM FROM TOE
OF SLOPE TO
APPROVED GROUND
EXISTING
GROUND SURFACE
BENCH HEIGHT
(4 FEET TYPICAL)
REMOVE
UNSUITABLE
MATERIAL
2 FEET MIN.
KEY OEPTH
LOWEST
BENCH (KEY)
HLL-OVei-CUT SLOPE
EXISTING
GROUND SURFACE
aiappJi BENCH I L-BENCH HEIGHT
(4 FEET TYPICAL)
REMOVE
UNSUITABLE
MATERIAL
CUT-OVB^-RLL SLOPE
-CUT FACE
SHALL BE CONSTRUCTED PRIOR TO
FILL PLACEMENT TO ALLOW VIEWNG /
OF GEOLOGIC CONDITIONS . ^
, /
EXISTING
GROUND
SURFACE
OVERBUILD AND
TRIM BACK
PROJECTED PLANE
1 TO 1 MAXIMUM
FROM TOE OF SLOPE
TO APPROVED GROUND
UT FACE SHALL BE
CONSTRUCTED PRIOR
TO FILL PLACEMENT
DESIGN SLOPE- j^^gRP*^^_[
BENCH
2 FEET MIN.-"
KEY DEPTH
REMOVE
UNSUITABLE
MATERIAL
I
:-:-:-2^"ijlM^$:-:"/
15 FEET MIN.
LOV\€ST
BENCH (KEY)
BENCH HEIGHT
(4 FEET TYPICAL)
BENCHING SHALL BE DONE WHEN SLOPE'S
ANGLE IS EQUAL TO OR GREATER THAN 5:1.
MINIMUM BENCH HEIGHT SHALL BE 4 FEET
AND MINIMUM FILL WIDTH SHALL BE 9 FEET.
KEYING AND BENCHING
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL A 4
-FINISH GRADE
SLOPE FACE i
^ .... . ..^wy^neamv:
OVERSIZE WINDROW
OVERSIZE ROCK IS LARGER THAN
8 INCHES IN LARGEST DIMENSION.
EXCAVATE A TRENCH IN THE COMPACTED
FILL DEEP ENOUGH TO BURY ALL THE
ROCK.
BACKFILL WITH GRANULAR SOIL JETTED
OR FLOODED IN PLACE TO FILL ALL THE
VOIDS.
DO NOT BURY ROCK WITHIN 10 FEET OF
FINISH GRADE
WINDROW OF BURIED ROCK SHALL BE
PARALLEL TO THE FINISHED SLOPE.
GRANULAR MATERIAL TO BE'
DENSIFIED IN PLACE BY
FLOODING OR JETTING.
DETAIL
-JETTED OR FLOODED
GRANULAR MATERIAL
TYPICAL PROFILE ALONG WINDROW
OVERSIZE ROCK
DISPOSAL
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL B 4
BENCHING
REMOVE
UNSUITABLE
MATERIAL
SUBDRAIN
TRENCH
SEE DETAIL BELOW
CALTRANS CLASS 2 PERMEABLE
OR |2 ROCK (9FT"3/FT) WRAPPED
IN FILTER FABRIC //
FILTER FABRIC
(MIRAFI UON OR APPROVED
EQUIVALENT)'
MIN. BEDDING
COLLECTOR PIPE SHALL
BE MINIMUM 6" DIAMETER
SCHEDULE 40 PVC PERFORATED
PIPE SEE STANDARD DETAIL D
FOR PIPE SPECIFICATIONS
SUBDRAIN DETAIL
DESIGN FINISH
GRADE
NONPERFORATED 6"0 MIN
PERFORATED
6" 0 MIN. PIPE
FILTER FABRIC
(MIRAFI UON OR APPROVED
EQUIVALENT)
CALTRANS CLASS 2 PERMEABLE
OR 12 ROCK (9FT''3/FT) WRAPPED
IN FILTER FABRIC
DETAIL OF CANYON SUBDRAIN WTIET
CANYON SUBDRAINS GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL C 4
15' MIN.
OUTLET PIPES
4" 0 NONPERFORATED PIPE.
100' MAX. O.C. HORIZONTALLY,
30' MAX O.C. VERTICALLY
BACK CUT
1:1 OR FLATTER
SEE SUBDRAIN TRENCH
DETAIL
LOWEST SUBDRAIN SHOULD
BE SITUATED AS LOW AS
POSSIBLE TO ALLOW
SUITABLE OUTLET
-KEY DEPTH
(2' MIN.)
KEY WIDTH
AS NOTED ON GRADING PLANS
(15' MIN.) 12" MIN. OVERLAP
FROM THE TOP HOG
RING TIED EVERY
6 FEET
CALTRANS CLASS II
PERMEABLE OR #2
ROCK (3 FT"3/FT)
WRAPPED IN FILTER
FABRIC
r-4" 0
\ NON-PERFORATED
\ OUTLET PIPE
T-CONNECTION
FOR COLLECTOR
PIPE TO OUTLET PIPE
6" MIN.
COVER
4" 0
f I PERFORATED
_L PIPE
PROVIDE POSITIVE
SEAL AT THE
JOINT
FILTER FABRIC
ENVELOPE (MIRAFI
140 OR APPROVED
EQUIVALENT)
4" MIN,
BEDDING
SUBDRAIN TRENCH DETAIL
SUBDRAIN INSTALLATION - subdroin collector pipe Shod be inslolled wilh perforation down or.
unless otherwise designoted by the geotechnicol consultant Outlet pipes shoH be non-perforoled
pipe The subdroin pipe sholl hove ot leost 8 perforotions uniformly spoced per foot. Perforotion
sholl be 1/4" to 1/2" if drill holes ore used. All subdroin pipes sholl hove a qrodieht of ot
leost 2% towords the outlet.
SUBDRAIN PIPE - Subdroin pipe sholl be ASTM 02751. SOR 23.5 or ASTM D1527. Schedule 40. or
ASTM 03034, SDR 23.5. Schedule 40 Polyvinyl Chloride Plostic (PVC) pipe.
All outlet pipe sholl be ploced in o trench no wider than twice the subdrain pipe.
BUTTRESS OR
REPLACEMENT
FILL SUBDRAINS
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL D 4
CUT-FILL TRANSITION LQT OVEREXCAVATION
REMOVE
UNSUITABLE
3R0UND•
OVEREXCAVATE
AND RECOMPACT
UNWEATf-ERED BEDROCK OR MATERIAL APPROVED
BY THE GEOTECHNICAL CONSULTANT-
TRANSITION LOT FILLS
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL E 4
SOIL BACKFILL, COMPACTED TO
90 PERCENT RELATIVE COMPACTION
BASED ON ASTM D1557
RETAINING WALL-
WALL WATERPROOFING
PER ARCHITECT'S
SPECIFICATIONS
WALL FOOTING
FILTER FABRIC ENVELOPE
(MIRAFI UON OR APPROVED
EQUIVALENT)"
-3/4" TO 1-1/2" CLEAN GRAVEL
-4" (MIN.) DIAMETER PERFORATED
PVC PIPE (SCHEDULE 40 OR
EQUIVALENT) WITH PERFORATIONS
ORIENTED DOWN AS DEPICTED
MINIMUM 1 PERCENT GRADIENT
TO SUITABLE OUTLET
COMPETENT BEDROCK OR MATERIAL
AS EVALUATED BY THE GEOTECHNICAL
CONSULTANT
NOTE: UPON REVIEW BY THE GEOTECHNICAL CONSULTANT,
COMPOSITE DRAINAGE PRODUCTS SUCH AS MIRADRAIN OR
J-DRAIN MAY BE USED AS AN ALTERNATIVE TO GRAVEL OR
CLASS 2 PERMEABLE MATERIAL. INSTALLATION SHOULD BE
PERFORMED IN ACCORDANCE WITH MANUFACTURER'S
SPECIFICATIONS.
RETAINING WALL
DRAINAGE
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL F 4
ACTIVE
ZONE
Gf^AVEL -
DRAINAGE FILL
MIN 6" BELOW WALL
MIN 12" BEHIND UNITS
FILTER FABRIC
REINFORCED
ZONE
FILTER FABRIC
WALL SUBDRAIN
BACKDRAIN
TO 70% OF
WALL HEIGHT
rFOUNDATION SOILSl
REAR SUBDRAIN:
4" (MIN) DIAMETER PERFORATED PVC PIPE
(SCHEDULE 40 OR EQUIVALENT) WITH
PERFORATIONS DOWN. SURROUNDED BY
1 CU. FT/FT OF 3/4" GRAVEL WRAPPED IN
FILTER FABRIC (MIRAFI 140N OR EQUIVALENT)
OUTLET SUBDRAINS EVERY 100 FEET, OR CLOSER,
BY TIGHTLINE TO SUITABLE PROTECTED OUTLET
GRAVEL DRAINAGE FILL: '
SIEVE SIZE % PASSING
1 INCH
3/4 INCH
NO. 4
NO. 40
NO. 200
100
75-100
0-60
0-50
0-5
NOTES:
1) MATERIAL GRADATION AND PLASTICITY
REINFORCED ZONF
SIEVE SIZE % PASSING
1 INCH 100
NO. 4 20-100
NO. 40 0-60
NO. 200 0-35
FOR WALL HEIGHT < 10 FEET, PLASTICITY INDEX < 20
FOR WALL HEIGHT 10 TO 20 FEET, PLASTICITY INDEX < 10
FOR TIERED WALLS, USE COMBINED WALL HEIGHTS
WALL DESIGNER TO REQUEST SITE-SPECIFIC CRITERIA FOR WALL HEIGHT > 20 FEET
2) CONTRACTOR TO USE SOILS WITHIN THE RETAINED AND REINFORCED ZONES THAT MEET THE STRENGTH REQUIREMENTS OF WALL DESIGN.
3) GEOGRID REINFORCEMENT TO BE DESIGNED BY WALL DESIGNER CONSIDERING INTERNAL, EXTERNAL, AND COMPOUND STABILITY.
3) GEOGRID TO BE PRETENSIONED DURING INSTALLATION.
4) IMPROVEMENTS WITHIN THE ACTIVE ZONE ARE SUSCEPTIBLE TO POST-CONSTRUCTION SETTLEMENT. ANGLE a 45+*/2, WHERE <C IS THE
FRICTION ANGLE OF THE MATERIAL IN THE RETAINED ZONE.
5) BACKDRAIN SHOULD CONSIST OF J-DRAIN 302 (OR EQUIVALENT) OR 6-INCII Tl lICK DRAINAGE FILL WRAPPED IN FILTER FABRIC. PERCENT
COVERAGE OF BACKDRAIN TO BE PER GEOTECHNICAL REVIEW.
SEGMENTAL
RETAINING WALLS
GENERAL EARTHWORK AND
GRADING SPECIFICATIONS
STANDARD DETAIL G 4
APPENDIX E
ASFE
mportant Iniormation about Your
Geotechnical Engineering Report
Subsurface problems are a principal cause of consfruction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
Geotechnical Services Are Performeii for Specific Purposes, Persons, and Projects
Geotechnical engineers structure ttieir services to meet ffie specific needs of
their clients. A geotechnical engineering study conducted for a civil engi-
neer may not fulfill the needs of a construction contractor or even another
civil engineer. Because each geotechnical engineering study is unique, each
geotechnical engineering report is unique, prepared so/e/yfor the client. No
one except you should rely on your geotechnical engineering report without
first conferring with the geotechnical engineer who prepared it. And no one
—not even you—should apply the report for any purpose or project
except the one originally contemplated.
Read tiie Fuii Report
Serious problems have occurred because those relying on a geotechnical
engineering report did not read it all. Do not rely on an executive summary
Do not read selected elements only
A Geoteciinical Engineering Report is Based on A Unique Set of Project-Specific Factors
Geotechnical engineers consider a number of unique, project-specific fac-
tors when establishing the scope of a study Typical factors include: the
client's goals, objectives, and risk management preferences; the general
nature of the structure involved, its size, and configuration; the location of
the structure on the site; and other planned or existing site improvements,
such as access roads, parking lots, and underground utilities. Unless the
geotechnical engineer who conducted the study specifically indicates
otherwise, do not rely on a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specific site explored, or
• completed before important projecf changes were made.
Typical changes that can erode the reliability of an existing geotechnical
engineering report include those fhat affect:
• the function of the proposed structure, as when it's changed from a
parking garage to an office buiiding, or from a light industrial plant
to a refrigerated warehouse.
• elevation, configuration, location, orientation, or weight of the
proposed structure,
• composition of the design team, or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
changes—even minor ones—and request an assessment of their impact,
Geotechnical engineers cannot accept responsibility or liability for problems
that occur because their reports do not consider developments of which
they were not informed
Sulisurf ace Conditions Can Cliange
A geotechnical engineering report is based on conditions that existed at the
time the study was performed. Do not rely on a geotechnical engineering
repo//whose adequacy may have been affected by: the passage of time; by
man-made events, such as construction on or adjacent to the site; or by
natural events, such as floods, earthquakes, or groundwater fluctuations.
Always contact the geotechnical engineer before applying the report to
determine if it is still reliable, A minor amount of additional testing or
analysis could prevent major problems.
Most Geoteciinicai Findings Are Professionai Opinions
Site exploration identifies subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. Geotechnical engi-
neers review field and laboratory data and then apply their professional
judgment to render an opinion about subsurface conditions throughout the
site. Actual subsurface conditions may differ—sometimes significantly—
from those indicated in your report. Retaining the geotechnical engineer
who developed your report to provide construction observation is the
most effective method of managing the risks associated with unanticipated
conditions,
A Report's Recommendations Are AArf Finai
Do not overrely on fhe construction recommendations included in your
report. Those recommendations are not final because geotechnical engi-
neers develop them principally from judgment and opinion, Geotechnical
engineers can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. The geotechnical
engineer who developed your report cannot assume responsibility or
liability for the report's recommendations if that engineer does not perform
construction observation.
A Geoteciinicai Engineering Report is Subject to Misinterpretation
other design team members' misinterpretation of geotechnical engineering
reports has resulted in costly problems. Lower that risk by having your geo-
technical engineer confer with appropriate members of the design team after
submitting the report. Also retain your geotechnical engineer to review perti-
nent elements of the design team's plans and specifications. Contractors can
also misinterpret a geotechnical engineering report. Reduce that risk by
having your geotechnical engineer participate in prebid and preconstruction
conferences, and by providing construction observation.
Do Not Redraw tiie Engineer's Logs
Geotechnical engineers prepare final boring and testing logs based upon
their interpretation of field logs and laboratory data. To prevent errors or
omissions, the logs included in a geotechnical engineering report should
never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable, but recognize
that separating logs from the report can elevate risl(.
Give Contractors a Compiete Report and Guidance
Some owners and design professionals mistakenly believe they can make
contractors liable for unanticipated subsurface conditions by limiting what
they provide for bid preparation. To help prevent costly protilems, give con-
tractors the complete geotechnical engineering report, i;yf preface it with a
clearly written letter of transmittal. In that letter, advise contractors that the
report was not prepared for purposes of bid development and that the
report's accuracy is limited; encourage them to confer with the geotechnical
engineer who prepared the report (a modest fee may be required) and/or to
conduct additional study to obtain the specific types of information they
need or prefer. A prebid conference can also be valuable. Be sure contrac-
tors have sufficient time to perform additional study Only then might you
be in a position to give contractors the best information available to you,
while requinng them to at least share some of the financial responsibilities
stemming from unanticipated conditions.
Read Responsibiiity Provisions Cioseiy
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering is far less exact than other engineenng disci-
plines. This lack of understanding has created unrealistic expectations that
have led to disappointments, claims, and disputes. To help reduce the risk
of such outcomes, geotechnical engineers commonly include a variety of
explanatory provisions in their reports. Sometimes labeled "limitations"
many of these provisions indicate where geotechnical engineers' responsi-
bilities begin and end, to help others recognize their own responsibilities
and risks. Read these provisions closely Ask questions. Your geotechnical
engineer should respond fully and frankly
Geoenvironmentai Concerns Are Not Covered
The equipment, techniques, and personnel used to perform a geoenviron-
mentai s[u6\/ differ significantly from those used to perform a geotechnical
study For that reason, a geotechnical engineering report does not usually
relate any geoenvironmentai findings, conclusions, or recommendations;
e.g., about the likelihood of encountering underground storage tanks or
regulated contaminants. Unanticipated environmental problems have led to
numerous project failures. If you have not yet obtained your own geoenvi-
ronmentai information, ask your geotechnical consultant for nsk manage-
ment guidance. Do not rely on an environmental report prepared for
someone else.
Obtain Professionai Assistance To Deai with Mold
Diverse strategies can be applied during building design, construction,
operation, and maintenance to prevent significant amounts of mold from
growing on indoor surfaces. To be effective, all such strategies should be
devised for the express purpose of mold prevention, integrated into a com-
prehensive plan, and executed with diligent oversight by a professional
mold prevention consultant. Because just a small amount of water or
moisture can lead to the development of severe mold infestations, a num-
ber of mold prevention strategies focus on keeping building surfaces dry
While groundwater, water infiltration, and similar issues may have been
addressed as parf of the geotechnical engineering study whose findings
are conveyed in this reporf, the geotechnical engineer in charge of this
project is not a mold prevention consultant; none of tlie services per-
formed in connecbon wiOi the geoteciinicai engineer's study
were designed or conducted for ttie purpose of mold preven-
tion. Proper implementation of tlie recommendattons conveyed
in tliis report wiil not of itself be sufficient to prevent mold from
growing in or on tlie structure involved.
Rely on Your ASFE-Member Geotechnical Engineer for Additional Assistance
Membership in ASFE/The Geoprofessional Business Association exposes
geotechnical engineers to a wide array of risk management techniques that
can be of genuine benefit for everyone involved with a construction project.
Confer with your ASFE-member geotechnical engineer for more information.
THE GEOPROFESSIONAL
BUSINESS ASSOCIATION
8811 Colesville Road/Suite G106, Silver Spring, MD 20910
Telephone: 301/565-2733 Facsimile: 301/589-2017
e-mail: info@asfe,org www,asfe,org
Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, Is strictly prohibited, except with ASFE's
specific written permission. Excerpting, quoting, or othen//ise extracting wording from this document is permitted only with the express written permission of ASFE, and only for
purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other
firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation.
IIGER01115.0MRP