HomeMy WebLinkAbout5210; Phase III Recycled Water , D-4 Reservoir; GEOTECHNICAL INVESTIGATION; 2019-04-24
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, CA
PROJECT NUMBER: 226816-0000111
NV5 West, Inc.
15092 Avenue of Science, Suite 200
San Diego, CA 92128
GEOTECHNICAL INVESTIGATION
April 24, 2019
Prepared For:
Carlsbad Municipal Water District
Ms. Shadi Sami, PE
5950 El Camino Real
Carlsbad, California 92008-8802
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Ms. Shadi Sami, PE April 24, 2019
Carlsbad Municipal Water District Project Number 226816-0000111
5950 El Camino Real
Carlsbad, California 92008-8802
Subject: Geotechnical Investigation Report
Project: Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Dear Ms. Sami:
As requested, NV5 West, Inc. (NV5) is pleased to submit the results of the geotechnical investigation
for the subject project. The purpose of this investigation was to evaluate the subsurface conditions for
the proposed additional recycled water storage tank at the Carlsbad Municipal Water District (CMWD)
D Tank site in Carlsbad, San Diego County, California.
It is understood that the proposed project will consist of the construction of a new 1.5 MG, steel or
prestressed concrete, recycled water storage tank. The new tank will have a shell height of
approximately 40 feet and a diameter of approximately 86 feet. The proposed reservoir is planned to
be located on an elevated pad at the site.
Based on the subsurface exploration, subsequent testing of the subsurface soils, and engineering
analyses, it was concluded that the construction of the proposed project is geotechnically feasible
provided the recommendations contained herein are appropriately incorporated into the design and
implemented during construction. The results of the geotechnical field explorations, laboratory tests,
and geotechnical engineering recommendations and conclusions are presented herewith.
It is recommended that the forthcoming project specifications, in particular, the earthwork/compaction
sections, be reviewed by NV5 for consistency with our report prior to the bid process in order to avoid
possible conflicts, misinterpretations, and inadvertent omissions, etc.
It should also be noted that the applicability and final evaluation of recommendations presented
herein are contingent upon construction phase field monitoring by NV5 in light of the widely
acknowledged importance of geotechnical consultant continuity through the various design, planning
and construction stages of a project.
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NV5 appreciates the opportunity to provide this geotechnical engineering service for this project and
looks forward to continuing our role as your geotechnical engineering consultant.
Respectfully submitted,
NV5 West, Inc.
Gene Custenborder, CEG 1319 Carl Henderson PhD, GE, 2886
Senior Engineering Geologist CQA Group Director (San Diego)
GC/CH:ma
Distribution: (1) Addressee, via email
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TABLE OF CONTENTS
PAGE
1.0 INTRODUCTION ........................................................................................................................ 1
2.0 SCOPE OF SERVICES .............................................................................................................. 1
3.0 Site and PROJECT DESCRIPTION .......................................................................................... 2
4.0 FIELD EXPLORATION PROGRAM .......................................................................................... 3
5.0 LABORATORY TESTING .......................................................................................................... 3
6.0 GEOLOGY .................................................................................................................................. 4
6.1 Geologic Setting ............................................................................................................................... 4
6.2 Geologic Materials ........................................................................................................................... 4
6.3 Groundwater ..................................................................................................................................... 5
6.4 Faults .................................................................................................................................................. 5
7.0 SEISMIC AND GEOTECHNICAL HAZARDS ............................................................................ 6
7.1 Fault Rupture .................................................................................................................................... 6
7.2 Seismic Shaking ............................................................................................................................... 6
7.3 Liquefaction and Seismically-Induced Settlement ..................................................................... 6
7.4 Landslides and Slope Instability .................................................................................................... 7
7.5 Subsidence ........................................................................................................................................ 7
7.6 Tsunamis, Inundation Seiches, and Flooding .............................................................................. 7
7.7 Expansive Soils ................................................................................................................................. 7
8.0 CONCLUSIONS ......................................................................................................................... 7
9.0 DESIGN RECOMMENDATIONS .............................................................................................. 8
9.1 General ............................................................................................................................................... 8
9.2 Earthwork .......................................................................................................................................... 8
9.3 Utility Trenching and Temporary Excavations .............................................................................. 9
9.4 Dewatering ...................................................................................................................................... 11
9.5 Trench Bottom Stability ................................................................................................................. 11
9.6 Conduit Bedding ............................................................................................................................. 11
9.7 Backfill Placement and Compaction ........................................................................................... 12
9.8 Foundations..................................................................................................................................... 12
9.8.1 Design Parameters .................................................................................................................. 12
9.8.2 Settlement ................................................................................................................................. 13
9.8.3 Foundation Observation .......................................................................................................... 13
9.9 Foundations For Ancillary Structures .......................................................................................... 14
9.10 Seismic Design Parameters ......................................................................................................... 14
9.11 Soil Corrosion .................................................................................................................................. 15
10.0 DESIGN REVIEW AND CONSTRUCTION MONITORING ..................................................... 17
10.1 Plans and Specifications ............................................................................................................... 17
10.2 Construction Monitoring ................................................................................................................ 17
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11.0 LIMITATIONS .......................................................................................................................... 17
12.0 SELECTED REFERENCES ...................................................................................................... 18
FIGURES
FIGURE 1 – SITE LOCATION MAP
FIGURE 2 – GEOTECHNICAL BORING MAP
FIGURE 3 – GEOLOGIC CROSS SECTION
FIGURE 4 – GENERAL GEOLOGIC MAP
FIGURE 5 – REGIONAL FAULT MAP
FIGURE 6 – LATERAL SURCHARGE LOADS
APPENDICES
APPENDIX A – EXPLORATORY BORING LOGS
APPENDIX B – LABORATORY TEST RESULTS
APPENDIX C – TYPICAL EARTHWORK GUIDELINES
APPENDIX D – GBA IMPORTANT INFORMATION ABOUT THIS GEOTECHNICAL REPORT
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1.0 INTRODUCTION
This report presents the results of NV5’s geotechnical investigation for an additional 1.5 MG recycled
water storage tank at the Carlsbad Municipal Water District’s D Tank site in Carlsbad, San Diego
County, California. The approximate location of the project area is shown in Figure 1, Site Location
Map.
The purpose of this study was to evaluate the subsurface conditions and to provide geotechnical
recommendations for the design and construction of the proposed water tank. This report summarizes
the data collected and presents our findings, conclusions and recommendations.
This report has been prepared for the exclusive use of the client and their consultants to describe the
geotechnical factors at the project site which should be considered in the design and construction of
the proposed project. Prospective bidders should consider it only as a source of general information
subject to interpretation and refinement by their own expertise and experience, particularly with regard
to construction feasibility. Contract requirements as set forth by the project plans and specifications
will supersede any general observations and specific recommendations presented in this report.
2.0 SCOPE OF SERVICES
NV5’s scope of services for this project included the following tasks:
Review of preliminary project plans, topographic maps, seismic hazard maps, geotechnical
maps and literature pertaining to the vicinity of the project.
A site reconnaissance to observe the general surficial site conditions and to select specific
boring locations.
Contacting Dig Alert to locate public utilities within the project site.
Coordinating with entities having an interest in the field exploration activities including the
design team, the drilling subcontractor (Baja Exploration), Underground Service Alert and
agencies associated with one-call notification.
Conducting a subsurface investigation, which included the drilling, logging and sampling of two
(2) exploratory borings located within the project area to depths ranging between
approximately27 to 30 ½ feet below ground surface (bgs). Soil samples obtained from the
borings were transported to NV5’s in-house laboratory for observation and testing.
Performing laboratory testing on selected representative bulk and relatively undisturbed soil
samples obtained during the field exploration program to evaluate their pertinent geotechnical
engineering properties.
Performing an assessment of general seismic conditions and geotechnical hazards affecting
the area and potential impacts on the subject project.
Engineering evaluation of the data collected to develop geotechnical recommendations for the
design and construction of the proposed project.
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Preparation of this report including reference maps and graphics, presenting our findings,
conclusions and geotechnical design recommendations specifically addressing the following
items:
o Evaluation of general subsurface conditions and description of types, distribution, and
engineering characteristics of subsurface materials.
o Evaluation of project feasibility including excavatability, trench stability, and suitability of
on-site soils for backfill.
o Recommendations and geotechnical parameters to be used for the design of the project.
3.0 SITE AND PROJECT DESCRIPTION
The project site is located in the southeast quadrant of the CMWD’s D tank site located on the east
side of Black Rail Road in the City of Carlsbad (refer to Figure 1, Site Location Map). The tank site area
is currently a relatively level graded pad at an elevation of approximately 375 feet above mean sea
level.
Based on preliminary information, it is understood that the proposed project will include grading of the
existing pad and construction of a new steel or prestressed concrete, recycled water storage tank at
CMWD’s D Tank site. The capacity of the new tank will be approximately 1.5 million gallons. The new
tank will have a shell height of approximately 40 feet and a diameter of approximately 86 feet. The
proposed water tank will rest on a flat graded pad approximately 8 feet above the existing ground
elevation. It is anticipated that mass grading will be performed to achieve the proposed grade if the
tank pad.
Reference: “Improvement Plans for D Tank Site Recycled Water Reservoir”, prepared by NV5, Inc., undated
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4.0 FIELD EXPLORATION PROGRAM
Before starting NV5’s field exploration program, Underground Service Alert was notified of our drilling
operations so that underground utility marking could be completed at the locations of exploration prior
to excavation. Subsequently, the subsurface conditions were explored on March 1, 2019 by drilling,
logging and sampling two (2) exploratory test borings (labeled B-1 through B-2)to maximum depths
ranging between about 27 to 30.5 feet bgs by Baja Exploration using a CME-75 hollow stem auger drill
rig. The approximate locations of the exploratory borings are presented on Figure 2, Geotechnical
Boring Map.
. The soil conditions encountered in the test borings were visually examined, classified, and logged in
general accordance with the Unified Soil Classification System by an NV5 geologist. The logs of the
exploratory test borings are presented in Appendix A, Exploratory Boring Logs. Bulk and relatively
undisturbed drive samples of the soils obtained from the borings were tagged in the field and
transported to our laboratory for further classification and testing. The drive samples were obtained
using the California Modified Split Spoon and Standard Penetration Test (SPT) samplers, as described
below. Subsequent to logging and sampling, the borings were backfilled with drill cuttings and
bentonite soil chips.
California Modified Split Spoon Sampler
The split barrel drive sampler was driven with a 140-pound hammer allowed to drop freely
30 inches in general accordance with ASTM D1587. The number of blows for the last two of
three 6-inch intervals were recorded during sampling and are presented in the logs of borings.
The sampler has external and internal diameters of approximately 3.0 and 2.4 inches,
respectively, and the inside of the sampler is lined with 1-inch-long brass rings. The relatively
undisturbed soil samples within the rings were removed, sealed, and transported to the
laboratory for observation and testing.
Standard Penetration Test (SPT) Sampler
A split barrel sampler was driven with a 140-pound hammer allowed to drop freely 30 inches
in general accordance with ASTM D1586. The numbers of blows for the last two of three, 6-inch
intervals were recorded during sampling and are presented in the logs of borings (i.e., N-value).
The sampler has external and internal diameters of 2.0 and 1.4 inches, respectively. The soil
samples obtained in the interior of the barrel were measured, removed, sealed and
transported to the laboratory for observation and testing.
5.0 LABORATORY TESTING
Laboratory testing was performed on selected representative bulk and relatively undisturbed soil
samples obtained from the exploratory borings, to aid in the material classifications and to evaluate
engineering properties of the materials encountered (see Appendix B). The following tests were
performed:
In-situ density and moisture content (ASTM D2937 and ASTM D2216);
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Particle size analyses and No. 200-wash (ASTM D422 and ASTM D6913);
Atterberg Limits (ASTM D4318);
Direct Shear tests (ASTM D3080);
Maximum dry density test (ASTM D1557);
R-Value tests (ASTM D2844);
Expansion index (ASTM D4829); and
Corrosivity test series, including sulfate content, chloride content, pH-value, and resistivity
(CTM 417, 422, and 643).
Testing was performed in general accordance with applicable ASTM standards or California Test
Methods. A summary of the laboratory testing program and the laboratory test results are presented
in Appendix B, Laboratory Test Results.
6.0 GEOLOGY
6.1 GEOLOGIC SETTING
The project is located in San Diego County within the coastal section of the Peninsular Ranges
geomorphic province. This province is characterized by northwest-trending mountain ranges bordered
by relatively straight-sided, sediment-floored valleys. The northwest trend is also reflected in the
direction of the dominant geologic structural features, which consist of northwest-southeast trending
faults and fault zones associated with the San Andreas and related fault systems. Two major
northwest-trending fault zones traverse the San Diego metropolitan and the inland county areas: the
Rose Canyon fault zone located to the west and the Elsinore fault zone located easterly of the site.
Typical stratigraphy in the Peninsular Ranges includes Mesozoic (between approximately 250 and
65 million years old) igneous intrusive and metamorphic rocks exposed in the eastern portion of the
province, Cenozoic (less than 65 million years old) marine and non-marine sedimentary units overlying
Mesozoic basement rocks in coastal areas and Quaternary (less than approximately 2 million years
old) alluvial deposits overlying older strata in valleys and larger drainages. The site is underlain at
depth by very old paralic deposits underlain by Tertiary formational sedimentary units (Santiago
Formation), although the Santiago Formation was not encountered at the depth investigated.
6.2 GEOLOGIC MATERIALS
Geologic materials encountered during the subsurface exploration consisted of very old paralic
deposits. Figure 4, General Geologic Map, presents the distribution of geologic units on a regional
scale. Detailed descriptions of the earth materials encountered are presented on the exploratory
boring logs in Appendix A, Exploratory Boring Logs. Generalized descriptions of the units encountered
in the field exploration are provided below:
• Quaternary-aged Very Old Paralic Deposits (Qvop) – Very old paralic deposits were
encountered in both borings, B-1 and B-2, to the total depth explored (maximum of
30.5 feet below the existing ground surface. As encountered, the very old paralic deposits
included a weathered “topsoil” layer consisting of brown, moist clayey sand that varied in
thickness from approximately 3 to 6 feet. The topsoil layer was underlain by the dense
formational materials which consisted of brown to orange brown, moist, medium dense to
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very dense silty sands and clayey sands. Drilling refusal was encountered in the paralic
deposits in borings B-1 and B-2 at depths of 30.5 and 27 feet, respectively.
6.3 GROUNDWATER
Indications of static, near-surface groundwater table were not observed or encountered during the
subsurface exploration to the total depth explored. It is anticipated that groundwater will not be a
constraint during construction. However, experience indicates that near-surface groundwater
conditions or localized seepage zones can develop in areas where no such groundwater conditions
previously existed, especially in areas where a substantial increase in surface water infiltration results
from landscape irrigation, agricultural activity, storage facility leaks or unusually heavy precipitation.
Seasonal variations in the groundwater levels should be anticipated.
6.4 FAULTS
The numerous faults in southern California include active, potentially active, and inactive faults. As
used in this report, the definitions of fault terms are based on those developed for the Alquist-Priolo
Special Studies Zones Act of 1972 and published by the California Division of Mines and Geology (Hart
and Bryant, 1997). Active faults are defined as those that have experienced surface displacement
within Holocene time (approximately the last 11,000 years) and/or have been included within any of
the state-designated Earthquake Fault Zones (previously known as Alquist-Priolo Special Studies
Zones). Faults are considered potentially active if they exhibit evidence of surface displacement since
the beginning of Quaternary time (approximately two million years ago) but not since the beginning of
Holocene time. Inactive faults are those that have not had surface movement since the beginning of
Quaternary time.
Review of geologic maps and literature pertaining to the general site area indicates that the site is not
located within a state-designated Earthquake Fault Zone. Review of the State of California, Special
Studies Zones indicates that the project site does not lie within an identified earthquake fault zone. In
addition, there are no known major or active faults mapped on the project site. Evidence for active
faulting at the site was not observed during the subsurface investigation. The relative location of the
site to known active faults in the region is depicted on Figure 5, Regional Fault Map. The distance from
the site to the projection of traces of surface rupture along major active earthquake fault zones, that
could affect the site are listed in the following Table 1.
Table 1 - Distance from the Site to Major Active Faults
Fault Name Distance From the Site
Newport Inglewood Connected 5.4 miles
Rose Canyon 5.4 miles
Newport-Inglewood (Offshore) 8.9 miles
Coronado Bank 21 miles
Palos Verdes Connected 21 miles
Elsinore 23 miles
Palos Verdes 38 miles
San Joaquin Hills 40 miles
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Earthquake Valley 41 miles
San Jacinto 48 miles
Chino 52 miles
San Andreas 64 miles
7.0 SEISMIC AND GEOTECHNICAL HAZARDS
The principal seismic considerations for most structures in southern California are damage caused by
surface rupturing of fault traces, ground shaking, seismically induced ground settlement and
liquefaction. Potential impacts to the project due to faulting, seismicity and other geologic hazards are
discussed in the following sections.
7.1 FAULT RUPTURE
The project site is not located within an Earthquake Fault Zone delineated by the State of California
for the hazard of fault surface rupture. The surface traces of known active or potentially active faults
are not known to pass directly through the site. The Alquist-Priolo (AP) mapped Newport-Inglewood-
Rose Canyon fault zone is located approximately 5.4 miles to the west and does not trend towards the
Site. Based on the distance to the mapped trace of the fault and the distance to other faults in the
vicinity of the site, the potential for damage due to surface rupture of faults at the project site is
considered low.
7.2 SEISMIC SHAKING
The project alignment is located in southern California, which is considered a seismically active area,
and as such the seismic hazard most likely to impact the site is ground shaking resulting from an
earthquake along one of the known active faults in the region. The seismic design of the project may
be performed using seismic design recommendations in accordance with the 2016 California Building
Code (CBC). Recommended seismic design parameters are presented in Section 9.10 of this report.
7.3 LIQUEFACTION AND SEISMICALLY-INDUCED SETTLEMENT
Liquefaction of soils can be caused by ground shaking during earthquakes. Research and historical
data indicate that loose, relatively clean granular soils are susceptible to liquefaction and dynamic
settlement, whereas the stability of the majority of clayey silts, silty clays and clays are not adversely
affected by ground shaking. Liquefaction is generally known to occur in saturated cohesionless soils
at depths shallower than approximately 50 feet. Dynamic settlement due to earthquake shaking can
occur in both dry and saturated sands.
The project alignment appears to be underlain (beneath anticipated groundwater depths)
predominately by moderately consolidated paralic deposits and formational sedimentary materials
which are not considered to be susceptible to liquefaction. Therefore, the potential for liquefaction and
the associated ground deformation occurring beneath the structural site areas is considered low.
Seismic settlement is often caused when loose to medium-dense granular soils are densified during
ground shaking.The primarily dense natural formational materials encountered in the exploratory
borings are not considered to be susceptible to seismic settlement.
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7.4 LANDSLIDES AND SLOPE INSTABILITY
The proposed tank pad location is located on relatively flat ground. Indications of deep-seated
landslides or slope instability were not observed during our investigation. Additionally there are no
known landslides on or near the project site, and the site is not located in the path of any known
landslides. Graded slopes and hillsides associated with existing residential developments are present
approximately 100 to 150 feet away (laterally) from the southeastern and eastern sides of the
proposed tank site. The geologic materials (formational) that comprise the majority of the hillside and
slope areas are characterized as having a “dense to very dense” apparent density with high shear
strength characteristics and are not known to be prone to landsliding. It is NV5’s opinion that the
potential damage to the proposed project due to landslides, lateral spreading or slope instability is
considered low provided the recommendations provided in this report are followed,
7.5 SUBSIDENCE
The project site is not located in an area of known ground subsidence due to the withdrawal of
subsurface fluids. Accordingly, the potential for subsidence occurring at the site due to the withdrawal
of oil, gas, or water is considered remote.
7.6 TSUNAMIS, INUNDATION SEICHES, AND FLOODING
Elevations along the project alignment range from approximately 350 to 376 feet above mean sea
level and the site is approximately 2 miles inland from the Pacific Ocean. Therefore, tsunamis (seismic
sea waves) are not considered a hazard at the site.
The site is not located near to or downslope of, any large body of water that could affect the site in the
event of an earthquake-induced failure or seiche (oscillation in a body of water due to earthquake
shaking).
7.7 EXPANSIVE SOILS
Improvements including foundations and slabs in contact with earth materials with a high potential for
expansion can be expected to be subject to distress based on the potential for volume change
associated with highly expansive soil. Soils such as these should not be relied upon for foundation
bearing. In addition, expansive soils are not typically suited for use as backfill for underground utilities.
The project alignment is underlain predominantly by moderately consolidated paralic deposits
consisting of silty sands and clayey sands. As evidenced by laboratory test results, these materials are
generally considered to have a very low to low expansion index. The majority of the on-site soils should
be generally suitable for re-use as engineered fill and/or trench backfill material if free of deleterious
materials and brought to near-optimum moisture conditions (either by wetting or drying as-necessary).
8.0 CONCLUSIONS
Based on the data obtained from the subsurface exploration, the associated laboratory test results,
engineering analyses, and experience with similar site conditions, it is NV5’s opinion that construction
of the proposed water tank is feasible from a geotechnical standpoint, provided the recommendations
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in this report are incorporated into the design plans and implemented during construction. The
following sections present detailed recommendations and parameters pertaining to the geotechnical
engineering design for this project.
9.0 DESIGN RECOMMENDATIONS
9.1 GENERAL
Minor amounts of localized topsoil materials consisting of clayey sand and silty sand were encountered
to depths of approximately 3 to 6 feet below the existing ground surface at the proposed project site.
This topsoil material is not considered capable of reliable support of the proposed water tank in its
present condition. Relatively dense, natural, silty and clayey sand materials were encountered below
the existing topsoil layer to the maximum depth explored. These soils are considered suitable for
supporting the proposed water tank and associated improvements. It is our understanding that the
new tank foundation will be constructed on an elevated graded pad. Prior to excavation of the ringwall,
the tank pad should be treated as in accordance with the following:
• To create uniform bearing support for the tank, the existing topsoil materials (encountered
to a maximum depth of 6 feet below the existing ground surface) should be removed and
properly recompacted in accordance with the earthwork recommendations provided in the
following sections.
9.2 EARTHWORK
Project earthwork should be performed in accordance with the following recommendations presented
herein. Site grading should be performed in accordance with the following recommendations and the
Typical Earthwork Guidelines provided in Appendix C. In the event of a conflict, the recommendations
presented herein supersede those of Appendix C.
• Clearing and Grubbing - Prior to grading, the project area should be cleared of all significant
surface vegetation, demolition rubble, trash, debris, etc. Any buried organic debris or other
unsuitable contaminated material encountered during subsequent excavation and grading
work should also be removed. Removed material and debris should be properly disposed
of offsite. Holes resulting from removal of buried obstruction which extend below finished
site grades should be filled with properly compacted soils. Any utilities within tank footprint
should be appropriately abandoned.
• Site Grading - The water tank should be founded entirely on a uniformly compacted fill pad.
A cut-fill transition condition should not be allowed underlying the tank. In order to create a
uniform bearing condition for the proposed water tank, including any adjacent perimeter
hardscape features (i.e., walls, walkways, etc.), all areas to receive surface improvements
or fill soils should be treated as follows:
o Tank Pad: To create uniform bearing support for the tank, the existing topsoil materials
(encountered to a maximum depth of 6 feet below the existing ground surface should
be removed. moisture conditioned to within 2 percent above the optimum moisture
content and placed in uniform lifts, approximately 8 inches in loose thickness and
compacted to a minimum of 95 percent relative compaction based on ASTM D1557.
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The removal should extend at least 5 feet outside of the perimeter of any proposed
fills.
o Excavatability: Based on our subsurface exploration, it is anticipated that the on-site
soils can be excavated by modern conventional heavy-duty excavating equipment in
good operating conditions.
o Structural Fill Placement: Areas to receive fill and/or surface improvements should be
scarified to a minimum depth of 6 inches, brought to near-optimum moisture
conditions, and compacted to at least 95 percent relative compaction, based on
laboratory standard ASTM D1557. Fill soils should be brought to near-optimum
moisture conditions and compacted in uniform lifts to at least 95 percent relative
compaction (ASTM D1557). Rocks with a maximum dimension greater than 4 inches
should not be placed in the upper 3 feet of pad grade. The optimum lift thickness to
produce a uniformly compacted fill will depend on the size and type of construction
equipment used. In general, fill should be placed in uniform lifts not exceeding 8 inches
in loose thickness. Placement and compaction of fill should be observed and tested by
the geotechnical consultant.
o Graded Slopes: Graded slopes should be constructed at a gradient of 2 to 1 (horizontal
to vertical) or flatter. To reduce the potential for surface runoff over slope faces, cut
slopes should be provided with brow ditches and berms should be constructed at the
top of fill slopes.
o Import Soils: If import soils are needed, proposed import should be sampled and
tested for suitability by NV5 prior to delivery to the site. Imported fill materials should
consist of clean granular soils free from vegetation, debris, or rocks larger than
3 inches maximum dimension. The Expansion Index value should not exceed a
maximum of 20 (i.e., essentially non-expansive).
9.3 UTILITY TRENCHING AND TEMPORARY EXCAVATIONS
Excavation of the on-site soils may be achieved with conventional heavy-duty grading equipment.
Temporary, unsurcharged, excavation walls may be sloped back at an inclination of 1:1(H:V) within fill
and natural materials. Utility trench excavations should be shored in accordance with guidelines and
regulations set forth by Cal-OSHA. For planning purposes, the alluvial and formational soils may be
considered a Type C soil, as defined by the current Cal-OSHA soil classification. Stockpiled (excavated)
materials should be placed no closer to the edge of a trench excavation than a distance defined by a
line drawn upward from the bottom of the trench at an inclination of 1:1 (H:V), but no closer than
4 feet. All trench excavations should be made in accordance with Cal-OSHA requirements.
Temporary, shallow excavations with vertical side slopes less than 4 feet high will generally be stable,
although due to the characteristics of the soil materials, there is a potential for localized sloughing. In
these soil types, vertical excavations greater than 4 feet high should not be attempted without proper
shoring to prevent local instabilities. For vertical excavations less than about 15 feet in height,
cantilevered shoring may be used. Cantilevered shoring may also be used for deeper excavations;
however, the total deflection at the top of the wall should not exceed one inch. Therefore, shoring of
excavations deeper than about 15 feet may need to be accomplished with the aid of tied back earth
anchors.
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O.2H
0.2H
0.6H H = Height of Excavation
(feet)
32H
(psf)
The actual shoring design should be performed by a registered civil engineer in the State of California
experienced in the design and construction of shoring under similar conditions. Once the final
excavation and shoring plans are complete, the plans and the design should be reviewed by NV5 for
conformance with the design intent and geotechnical recommendations. The shoring system should
further satisfy requirements of Cal-OSHA. In some areas, shoring may be accomplished with hydraulic
shores and trench plates, soldier piles and lagging and/or trench boxes. The actual method of a
shoring system should be provided and designed by a contractor experienced in installing temporary
shoring under similar soil conditions. If soldier piles and lagging are to be used, we should be contacted
for additional recommendations.
Personnel from NV5 should observe the excavation so that any necessary modifications based on
variations in the encountered soil conditions can be made. All applicable safety requirements and
regulations, including Cal-OSHA requirements, should be met.
Where sloped excavations are used, the tops of the slopes should be barricaded so that vehicles and
storage loads are not located within 10 feet of the tops of excavated slopes. A greater setback may be
necessary when considering heavy vehicles, such as concrete trucks and cranes. NV5 should be
advised of such heavy loadings so that specific setback requirements may be established. If the
temporary construction slopes are to be maintained during the rainy season, berms are recommended
along the tops of the slopes, to prevent runoff water from entering the excavation and eroding the
slope faces.
For design of cantilevered shoring, a triangular distribution of lateral earth pressure may be used. It
may be assumed that the drained soils, with a level surface behind the cantilevered shoring, will exert
an equivalent fluid pressure of 32 pcf. Tied-back or braced shoring should be designed to resist a
trapezoidal distribution of lateral earth pressure. The recommended pressure distribution, for the case
where the grade is level behind the shoring, is illustrated in the following diagram with the maximum
pressure equal to 32H in psf, where H is the height of the shored wall in feet.
Any surcharge (live, including traffic, or dead load) located within a 1:1 (H:V) plane drawn upward from
the base of the shored excavation should be added to the lateral earth pressures. The lateral load
contribution of a uniform surcharge load located across the 1:1 (H:V) zone behind the excavation walls
may be calculated by using Figure 6, Lateral Surcharge Loads. Lateral load contributions of surcharges
226816-0000111 NV5.COM | 11
can be provided once the load configurations and layouts are known. As a minimum, a 2-foot
equivalent soil surcharge is recommended to account for nominal construction loads.
9.4 DEWATERING
Groundwater was not encountered to the maximum depth explored of approximately 30.5 feet below
the existing ground surface. Dewatering is not generally anticipated during the proposed construction.
However, any cases of localized seepage or heavy precipitation should be monitored during
construction. If necessary, dewatering may be achieved by means of excavating a series of shallow
trenches directed by gradient (i.e., gravity) to sumps with pumps. In any case, the actual means and
methods of any dewatering scheme should be established by a contractor with local experience. It is
important to note that temporary dewatering, if necessary, will require a permit and plan that complies
with the State of California San Diego Regional Water Quality Control Board regulations. If excessive
water is encountered, NV5 should be contacted to provide additional recommendations for temporary
construction dewatering. Based on the subsurface exploration the onsite soils maybe considered to
be relatively permeable.
9.5 TRENCH BOTTOM STABILITY
The bottom of onsite excavations may likely expose moderately consolidated silty sands and clayey
sands. These soils should provide a suitable base for construction of pipelines provided design is
based upon the recommendations provided herein. For the design of flexible conduits, a modulus of
soil reaction (E’), of 1,000 pounds per square inch (psi) is recommended.
While groundwater was not encountered, if these soils become wet or saturated they may be prone to
settlement due to construction activities such as placement and compaction of backfill soils. Buried
improvements underlain by these soils could also be damaged or subjected to unacceptable
settlement due to subsidence of these soils. If wet or unusually soft conditions are encountered in the
trench bottom, the bottom of the excavations will need to be stabilized. A typical stabilization method
includes overexcavation of the soft or saturated soil and replacement with properly compacted fill,
gravel or lean concrete to form a "mat" or stable working surface in the bottom of the excavation. There
are other acceptable methods that can be implemented to mitigate the presence of compressible soils
or unstable trench bottom conditions, and specific recommendations for a particular alternative can
be discussed based on the actual construction techniques and conditions encountered.
9.6 CONDUIT BEDDING
It is recommended that conduit bedding materials be placed in the trench to provide uniform support
and protection. This zone shall be compacted to a minimum of 90% relative compaction. Care should
be taken by the contractor during placement of the pipe bedding so that uniform contact between the
bedding and conduit is attained. Bedding should be placed in loose lift thicknesses not exceeding
8 inches and compacted by mechanical means to attain a relative compaction of 90 percent based
on ASTM D1557. There should be sufficient clearance along the sides of the conduits to allow for
compaction equipment. The bedding should be compacted under the haunches and alongside the
conduit. Mechanical compaction and hand tamping should be performed carefully as to not damage
the conduits. Backfill material should be compacted in accordance with the recommendations in
Section 9.2 of this report.
226816-0000111 NV5.COM | 12
9.7 BACKFILL PLACEMENT AND COMPACTION
The majority of the on-site soils should generally be suitable for use as backfill material. Backfill should
be placed in loose lifts not exceeding 8 inches in thickness and compacted to at least 90 percent of
the maximum dry density as evaluated by the latest version of ASTM D1557. Trench backfill should be
compacted in uniform lifts (not exceeding 8 inches in loose lift thickness) by mechanical means to at
least 90 percent relative compaction (ASTM D1557).
Imported backfill should consist of granular, non-expansive soil with an Expansion Index (EI) of 20 or
less and should not contain any contaminated soil, expansive soil, debris, organic matter, or other
deleterious materials. The Sand Equivalent (SE) of the imported material shall be 20 or greater. Import
material should be evaluated for suitability by the geotechnical consultant prior to transport to the site.
The upper 12 inches of subgrade soil and all rock base should be compacted to at least 95 percent.
The moisture content of the backfill should be maintained within 2 percent of optimum moisture
content during compaction. All backfill should be mechanically compacted. Flooding or jetting is not
recommended and should not be allowed.
9.8 FOUNDATIONS
The tank pad foundation should be founded entirely in natural material. Recommendations for the
design and construction of foundation system are presented below.
9.8.1 Design Parameters
The tank pad foundation should be designed using the geotechnical design parameters
presented in the following Table 2. Footings should be designed and reinforced in accordance
with the recommendations of the structural engineer and should conform to the latest edition
of the California Building Code.
226816-0000111 NV5.COM | 13
Table 2 - Geotechnical Design Parameters
Ringwall Footing for Proposed Water Tanks
Ringwall Foundation
Dimensions
Continuous ringwall foundation at least 24
inches in width and at least 24 inches below the
lowest adjacent grade
Allowable Bearing Capacity
(dead-plus-live load)
4,000 pounds per square foot (psf)
A one-third (1/3) increase is allowed for
transient live loads from wind or seismic forces.
Reinforcement Reinforce in accordance with requirements as
provided by the project Structural Engineer.
Allowable Coefficient of
Friction 0.45
Allowable Lateral Passive
Pressure Resistance
(Equivalent Fluid Pressure)
325 pounds per cubic foot (pcf)
One third (1/3) increase in passive pressure
resistance may be used for wind and seismic
loads.
The total allowable lateral resistance may be
taken as the sum of the frictional resistance
and the passive resistance, provided that the
passive bearing resistance does not exceed two-
thirds (2/3) of the total allowable resistance.
9.8.2 Settlement
Estimated settlements will depend on the foundation size and depth, and the loads imposed
and the allowable bearing values used for design. For preliminary design purposes, the total
static settlement for the continuous ringwall foundation loaded to accordance with the
allowable bearing capacities recommended above is estimated to be less than 1 inch.
Differential settlements will depend on the foundation size and depth, and the loads imposed.
However, based on our knowledge of the project, differential static settlements are anticipated
to be 0.5 inch or less
9.8.3 Foundation Observation
To verify the presence of satisfactory materials at design elevations, footing excavations
should be observed by a geotechnical engineer to be clean of loosened soil and debris
before placing steel or concrete and probed for soft areas.
226816-0000111 NV5.COM | 14
9.9 FOUNDATIONS FOR ANCILLARY STRUCTURES
A shallow foundation system may be used for support of relatively lightly loaded ancillary structures,
such as site screen walls, light standards, etc. The foundations for each feature should be supported
entirely in natural soil or on compacted fill prepared in accordance with the recommendations in
Section 9.2 of this report. Footings should be designed and reinforced in accordance with the
recommendations of the structural engineer and should conform to the latest edition of the California
Building Code. Recommendations for the design and construction of these shallow foundations are
presented in the following Table 3.
Table 3 - Geotechnical Design Parameters
Spread Footing Foundations for Ancillary Structures
Foundation Dimensions At least 12 inches below the lowest adjacent
grade and at least 12 inches in width
Allowable Bearing Capacity
(dead-plus-live load)
3,000 pounds per square foot (psf). The
allowable bearing value may be increased by
one-third (1/3) for transient live loads such as
from wind or seismic forces.
Estimated Static Settlement
(Total/Differential) Less than 1-inch/ less than ½-inch
Allowable Coefficient of
Friction 0.45
Allowable Lateral Passive
Pressure Resistance
325 pounds per cubic foot (pcf)
One-third (1/3) increase in passive pressure
resistance may be used for wind and seismic
loads.
The total allowable lateral resistance may be
taken as the sum of the frictional resistance
and the passive resistance, provided that the
passive bearing resistance does not exceed two-
thirds (2/3) of the total allowable resistance.
9.10 SEISMIC DESIGN PARAMETERS
Preliminary seismic parameters were developed for the project site based on the 2016 California
Building Code (CBC) and ASCE 7-10 guidance document. Using the California SEA U.S. Seismic Design
Maps Online Calculator (https://seismicmaps.org/) based on the following site coordinates: Latitude
= 33.111985 degrees, and Longitude = -117.286392 degrees. The earthquake hazard level of the
Maximum Considered Earthquake (MCE) is defined in ASCE 7-10 as the ground motion having a
226816-0000111 NV5.COM | 15
probability of exceedance of 2 percent in 50 years. The preliminary seismic design parameters for the
project site are presented in Table 4 below.
Table 4 - Recommended 2016 CBC Seismic Design Parameters
Design Parameter Recommended
Value Reference
Site Class C ASCE 7-10 Section 11.4.2
Mapped Spectral Accelerations for short
periods, SS 1.088g ASCE 7-10 Section 11.4.3
Mapped Spectral Accelerations for 1-sec
period, S1 0.42g ASCE 7-10 Section 11.4.3
Short-Period Site Coefficient, Fa 1.0 ASCE 7-10 Section 11.4.3
Long-Period Site Coefficient, Fv 1.38 ASCE 7-10 Section 11.4.3
(1) MCER (5% damped) spectral response
acceleration for short periods adjusted for
site class, SMS
1.088g ASCE 7-10 Section 11.4.3
(1) MCER (5% damped) spectral response
acceleration at 1-second period adjusted
for site class, SM1
0.579g ASCE 7-10 Section 11.4.3
Design spectral response acceleration
(5% damped) at short periods, SDS 0.726g ASCE 7-10 Section 11.4.3
Design spectral response acceleration
(5% damped) at 1-second period, SD1 0.386g ASCE 7-10 Section 11.4.3
Seismic Design Category D ASCE 7-10 Section 11.6
(2) MCEG Peak Ground Acceleration
adjusted for site class effects, PGAM 0.427g ASCE 7-10 Section 11.8.3
(1) MCER = Risk-adjusted Maximum Considered Earthquake
(2) MCEG = Geometric-mean Maximum Considered Earthquake
9.11 SOIL CORROSION
The corrosion potential of the on-site materials to steel and buried concrete was evaluated. Laboratory
testing was performed on a representative sample of the existing artificial fills to evaluate pH,
minimum resistivity, and chloride and soluble sulfate content. Table 5 below presents the results of
the corrosivity testing. General recommendations to address the corrosion potential of the on-site soils
are provided below. If additional recommendations are desired, it is recommend that a corrosion
specialist be consulted.
226816-0000111 NV5.COM | 16
Table 5 - Corrosivity Test Results
Test
Location
Material
Type
Depth
(feet) pH
Minimum
Resistivity
(ohm-cm)
Water
Soluble
Sulfate
Content
(ppm)
Water
Soluble
Chloride
Content
(ppm) B-1 Clayey SAND (SC) 3 - 5 7.6 2100 54 64
B-2 Clayey SAND (SC) 8 - 10 5.9 1400 33 64
Caltrans Corrosion Guidelines dated March 2018 considers a site to be corrosive if one or more of the
following conditions exist for the representative soil samples taken at the site:
Chloride concentration is 500 ppm or greater, sulfate concentration is 1500 ppm or greater,
or the pH is 5.5 or less
Based on experience and the Caltrans Corrosion Guidelines, the site soils are not considered corrosive
to steel reinforced concrete foundation elements with respect to sulfate and chloride concentration
and pH.
As indicated in the 2006 edition (second edition) of “Corrosion Basics - An Introduction”, a general
guideline for soil resistivity and corrosion-severity ratings is presented in the following Table 6.
Table 6 - Corrosivity Test Results
Soil Resistivity Corrosivity
<1,000 ohm-cm Extremely Corrosive
1,000 to 3,000 ohm-cm Highly Corrosive
3,000 to 5,000 ohm-cm Corrosive
5,000 to 10,000 ohm-cm Moderately Corrosive
10,000 to 20,000 ohm-cm Mildly Corrosive
>20,000 ohm-cm Essentially Noncorrosive
Soil resistivity is not the only parameter affecting the risk of corrosion damage; and a high soil
resistivity will not guarantee the absence of serious corrosion. For example, the American Water Works
Association (AWWA) has developed a numerical soil-corrosivity scale, applicable to cast-iron alloys. The
soil resistivity test results suggest the potential for soils to be highly corrosive to ferrous pipes.
Any imported soils should be evaluated for corrosion characteristics if they will be in contact with
buried or at-grade structures and appropriate mitigation measures should be included in the structure
design. It is recommended that a corrosion specialist be contacted to determine if mitigation measures
are necessary.
226816-0000111 NV5.COM | 17
10.0 DESIGN REVIEW AND CONSTRUCTION MONITORING
Geotechnical review of plans and specifications is of paramount importance in engineering practice.
Observation and testing of the backfill, subgrade and base will be important to the performance of the
proposed project. The following sections present our recommendations relative to the review of
construction documents and the monitoring of construction activities.
10.1 PLANS AND SPECIFICATIONS
The design plans and specifications will be reviewed and approved by NV5 prior to construction, as
the geotechnical recommendations may need to be re-evaluated in the light of the actual design
configuration. This review is necessary to evaluate whether the recommendations contained in this
report and future reports have been properly incorporated into the project plans and specifications.
10.2 CONSTRUCTION MONITORING
Site preparation, removal of unsuitable soils, assessment of imported fill materials, backfill placement,
and other earthwork operations should be observed and tested. The substrata exposed during the
construction may differ from that encountered in the test borings. Continuous observation by a
representative of NV5 during construction allows for evaluation of the soil/rock conditions as they are
encountered and allows the opportunity to recommend appropriate revisions where necessary.
11.0 LIMITATIONS
The recommendations and opinions expressed in this report are based on NV5’s review of background
documents and on information developed during this study. It should be noted that this study did not
evaluate the possible presence of hazardous materials on any portion of the site. More detailed
limitations of this geotechnical study are presented in GBA’s information bulletin in Appendix D.
Due to the limited nature of our field explorations, conditions not observed and described in this report
may be present on the site. Uncertainties relative to subsurface conditions can be reduced through
additional subsurface exploration. Additional subsurface evaluation and laboratory testing can be
performed upon request. It should be understood that conditions different from those anticipated in
this report may be encountered during the proposed structure construction operations.
Site conditions, including ground-water level, can change with time as a result of natural processes or
the activities of man at the subject site or at nearby sites. Changes to the applicable laws, regulations,
codes, and standards of practice may occur as a result of government action or the broadening of
knowledge. The findings of this report may, therefore, be invalidated over time, in part or in whole, by
changes over which NV5 has no control.
NV5’s recommendations for this site are, to a high degree, dependent upon appropriate quality control
of subgrade preparation, fill/backfill placement, etc. Accordingly, the recommendations are made
contingent upon the opportunity for NV5 to observe grading operations and foundation excavations
for the proposed construction. If parties other than NV5 are engaged to provide such services, such
parties must be notified that they will be required to assume complete responsibility as the
226816-0000111 NV5.COM | 18
geotechnical engineer of record for the geotechnical phase of the project by concurring with the
recommendations in this report and/or by providing alternative recommendations.
This document is intended to be used only in its entirety. No portion of the document, by itself, is
designed to completely represent any aspect of the project described herein. NV5 should be contacted
if the reader requires additional information or has questions regarding the content, interpretations
presented, or completeness of this document.
NV5 has endeavored to perform this study using the degree of care and skill ordinarily exercised under
similar circumstances by reputable geotechnical professionals with experience in this area in similar
soil/rock conditions. No other warranty, either expressed or implied, is made as to the conclusions
and recommendations contained in this study.
12.0 SELECTED REFERENCES
Anderson, J.G., 1979, Estimating the seismicity from geologic structure, for seismic-risk studies:
Bulletin of the Seismological Society of America, v. 69, p. 135-158.
ASTM, 2001, Soil and Rock: American Society for Testing and Materials: vol. 4.08 for ASTM test
methods D-420 to D-4914; and vol. 4.09 for ASTM test methods D-4943 to highest number.
Bird, P., and Rosenstock, R.W., 1984, Kinematics of present crust and mantle flow in southern
California: Geological Society of America Bulletin, v. 95, p. 946-957.
California Department of Conservation, Division of Mines and Geology, 1997, Guidelines for Evaluation
and Mitigation of Seismic Hazards in California: Special Publication 117, 74 pp.
California Department of Conservation, Division of Mines and Geology, 1998, Maps of Known Active
Fault Near-Source Zones in California and Adjacent Portions of Nevada: International
Conference of Building Officials, dated February, Scale 1” = 4 km.
California Department of Transportation, 2018, Corrosion Guidelines. Version 3.0, dated March.
Campbell, K.W., 1997, Empirical Near-Source Attenuation Relationships for Horizontal and Vertical
Components of Peak Acceleration, Peak Ground Velocity, and Psuedo-Absolute Acceleration
Response Spectra: Seismological Research Letters, Vol. 68, No. 1, pp. 154-179.
Campbell, K.W., 2000, Erratum, Empirical Near-Source Attenuation Relationships for Horizontal and
Vertical Components of Peak Acceleration, Peak Ground Velocity, and Psuedo-Absolute
Acceleration Response Spectra: Seismological Research Letters, Vol. 71, No. 3, pp. 353-355.
Dziewonski, A.M., Ekström, G., and Salganick, M.P., 1993, Centroid moment tensor solutions for April-
June 1992: Physical Earth Planet Interiors, v. 77, p. 151-163.
Hart, E.W., and Bryant, W.A., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake
Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of
Conservation, Division of Mines and Geology Special Publication 42, 38 pp.,
226816-0000111 NV5.COM | 19
Idriss, I.M. and Boulanger, R.W., 2008, Soil Liquefaction During Earthquakes, EERI, MNO-12, Oakland,
CA
Ishihara, K., 1985, Stability of Natural Deposits during Earthquakes: Proceedings, 11th International
Conference on Soil Mechanics and Foundation Engineering, Volume 1, pp. 321-376.
Kennedy, M.P., and Tan, S.S., 2007, Geologic Map of the Oceanside 30’ x 60’ Quadrangle, California.
Regional Geologic Map Series, 1:100,000 Scale, Map No. 2.
Petersen, M.D., and Wesnousky, S.G., 1994, Fault slip rates and earthquake histories for active faults
in southern California: Bulletin of the Seismological Society of America, v. 84, no. 5, p. 1,608-
1,649.
Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Lienkaemper, J.J.,
McCrory, P.A., and Schwartz, D.P., 1996, Probabilistic seismic hazard assessment for the State
of California: California Department of Conservation, Division of Mines and Geology Open-File
Report 96-08 (also U.S. Geological Open-File Report 96-706), 33 p.
Seed, R.B., K.O., Cetin, R.E.S., Moss, A., Kammerer, J., Wu, J.M., Pestana, M.F., Riemer, R.B., Sancio,
J.D., Bray, R.E., Kayen, R.E., Faris, A., 2003, "Recent Advances in Soil Liquefaction Engineering:
a unified and consistent framework,” Keynote Address, 26th Annual Geotechnical Spring
Seminar, Los Angeles Section of the GeoInstitute, American Society of Civil Engineers, H.M.S.
Queen Mary, Long Beach, California, USA
Southern California Earthquake Center, 1999, Recommended Procedures for Implementation of DMG
Special Publication 117 Guidelines for Analyzing and Mitigating Liquefaction in California:
dated March, 63 pp.
Southern California Earthquake Center, 2002, Recommended Procedures for Implementation of DMG
Special Publication 117 Guidelines for Analyzing and Mitigating Landslide Hazards in
California: dated March, 127 pp.
Wesnousky, S.G., 1986, Earthquakes, Quaternary faults, and seismic hazards in California: Journal of
Geophysical Research, v. 91, no. B12, p. 12,587-12,631.
226818-0000111 NV5.COM |
FIGURES
Project No:226818-0000111
Drawn:SB
Date:Mar 2019 Figure No. 1
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400 NSite Location Map
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Reference: Google Earth 2019
0 1000 2000 3000 4000 5000
Approximate scale in feet
Approximate Location
Project Site
Project No:226818-0000111
Drawn:SB
Date:Mar 2019 Figure No. 2
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400 NGeotechnical Boring Map
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Reference: Google Earth 2019
MAP SYMBOLS
Approximate location of geotechnical boring B-2
Approximate location of geologic cross section A A’
B-2
B-1
A’
A
Approximate location of proposed water tank
Approximate scale in feet
0 50 100 150 200 250
Project No:226818-0000111
Drawn:SB
Date:Mar 2019 Figure No. 3
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
Geologic Cross Section
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
SYMBOLS
Approximate location of geologic cross section A A’
Approximate location of proposed water tank
Approximate scale in feet
0 50 100 150 200 250
A
350
400
250
300
A’
Trend of Section A - A’ : E 15 S
B-1Projected 10' Northeast
Proposed
Water Tank
B-2Projected 40' Northeast
Qvop
For Schematic Use Only-Not a Construction Drawing
Very old paralic deposits
Existing
Grade
Proposed
Grade
Qvop Qvop
Elevation
(feet)
Figure No. 4
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400 N
MAP SYMBOLS
Reference:Geologic Map of the Oceanside 30' x 60' Quadrangle, San Diego County, California. Kennedy,
K.P., Tan, S.S., 2007. Regional Geologic Map Series, scale 1:100,000. Map No. 2.
General Geologic Map
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Project No:226818-0000111
Drawn:SB
Date:Mar 2019
Approximate scale in feet
0 2000 4000 6000 8000 10,000
Approximate Location
Project Site
For Schematic Use Only-Not a Construction Drawing
Figure No. 5
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
Map of southern California showing the geographic regions, faults and focal mechanisms of the more significant
earthquakes. Regions: Death Valley, DV; Mojave Desert MD; Los Angeles, LA; Santa Barbara Channel, SBC; and San Diego,
SD. Indicated Faults: Banning fault, BF; Channel Island thrust, CIT; Chino fault, CF; Eastern California Shear Zone, ECSZ;
Elsinore fault, EF; Garlock fault, GF; Garnet Hill fault, GHF; Lower Pitas Point thrust, LPT; Mill Creek fault, MICF; Mission
Creek fault, MsCF; Northridge fault, NF; Newport Inglewood fault, NIF; offshore Oak Ridge fault, OOF; Puente Hills thrust,
PT; San Andreas fault (sections: Parkfield, Pa; Cholame, Ch; Carrizo; Ca; Mojave, Mo; San Bernardino, Sb; and Coachella,
Co); San Fernando fault, SFF; San Gorgonio Pass fault, SGPF; San Jacinto fault, SJF; Whittier fault, WF; and White Wolf fault,
WWF. Earthquake Focal Mechanisms: 1952 Kern County, 1; 1999 Hector Mine, 2; 1992 Big Bear, 3; 1992 Landers, 4; 1971
San Fernando, 5; 1994 Northridge, 6; 1992 Joshua Tree, 7; and 1987 Whittier Narrows, 8.
Reference:Plesch, Anndreas et. al., 2007, Community Fault Model (CFM) for
Southern California; in the Bulletin of the Seismological Society of
America, Vol. 97, No. 6. pp. 1793-1802, dated December.
Approximate
Site Location
Regional Fault Map
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Project No:226818-0000111
Drawn:SB
Date:Mar 2019
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200,
San Diego, CA
Tel: (858) 385-0500, Fax: (858) 385-0400
Lateral Surcharge Loads
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, CA
Project No: 226818-0000111
Drawn: SB
Date: Mar 2019 Figure No. 6
226818-0000111 NV5.COM |
APPENDIX A
Exploratory Boring Logs
226818-0000111 NV5.COM |
Logs of Exploratory Borings
Bulk and relatively undisturbed drive samples were obtained in the field during our subsurface
evaluation. The samples were tagged in the field and transported to our laboratory for observation
and testing. The drive samples were obtained using the Modified California Sampler (CAL) and
Standard Penetration Test (SPT) samplers as described below.
Modified California Split Spoon Sampler
The split barrel drive sampler is driven with a 140-pound hammer allowed to drop freely 30 inches in
general accordance with ASTM D1587. The number of blows per foot recorded during sampling is
presented in the logs of exploratory borings. The sampler has external and internal diameters of
approximately 3.0 and 2.4 inches, respectively, and the inside of the sampler is lined with 1-inch-long
brass rings. The relatively undisturbed soil sample within the rings is removed, sealed, and transported
to the laboratory for observation and testing.
Standard Penetration Test (SPT) Sampler
The split barrel sampler is driven with a 140-pound hammer allowed to drop freely 30 inches in
general accordance with ASTM D1586. The number of blows per foot recorded during sampling is
presented in the logs of exploratory borings. The sampler has external and internal diameters of 2.0
and 1.4 inches, respectively. The soil sample obtained in the interior of the barrel is measured,
removed, sealed and transported to the laboratory for observation and testing.
Chart 1
Title:
Project:
Project No: 226818-0000111
Drawn: SB
Date: Mar 2019
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA 92128
Tel: (858) 385-0500, Fax: (858) 385-0400
Boring Log Legend
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Chart 2
Soil Classification
Carlsbad Municipal Water District
Phase III Recycled Water Project
Carlsbad, California
Title:
Project:
Project No: 226818-0000111
Drawn: SB
Date: Mar 2019
NV5
An NV5 West, Inc. Company – Offices Nationwide
15092 Avenue of Science, Suite 200
San Diego, CA 92128
Tel: (858) 385-0500, Fax: (858) 385-0400
6.0'
12.0'
27.0'
30.0'
30.5'
9.7
11.8
11.8
8.5
3.3
7.1
8.6
8.1
9.1
8
13
17
21
21
27
37
50/2"
37
35
45
50/4"
50/6"
Sieve Analysis
Maximum Density
Expansion Index
Atterberg Limits
Moisture Content
Corrosivity
Direct Shear
Moisture Content
Moisture Content
Moisture Content
Moisture / Density
Moisture Content
Moisture / Density
Moisture Content
G- 1
MC- 1
G- 2
SPT- 1
G- 3
MC- 2
SPT- 2
MC- 3
G- 4
SPT- 3
SC
SC
SM
SC
SM
115.8
110.8
104.5
[TOPSOIL] Clayey SAND (SC): Brown, moist
Medium Dense
[FORMATIONAL - Qvop] Clayey SAND (SC): Orange
brown, moist
Dense
[FORMATIONAL - Qvop] Silty SAND (SM): Orange brown,
moist
Very Dense
Very Dense
Color change to brown. Grain size increase. Decrease in fines
Very Dense
[FORMATIONAL - Qvop] Clayey SAND (SC): Brown, moist
[FORMATIONAL - Qvop] Silty SAND (SM): Orange brown,
moist, very dense
El. 370.0'
El. 364.0'
El. 349.0'
El. 346.0'
El. 345.5'
Notes: Drilled using a 6.5" O.D. Hollow Stem Auger. Boring terminated at depth of
30.5'. Groundwater not encountered. Backfilled with cuttings and bentonite
chips. Refusal in dense formational material.
Date
Graphical LogProject Number
Boring Log
B-1
Depth (ft.)Longitude: -117.286392°
Sample Type
Boring No.
Groundwater
G - Bulk / Grab SampleSPT - 2" O D. 1.4" I.D. Tube SampleMC - 3 " O.D. 2.4" I D. Ring SampleNR - No Recovery* - Uncorrected Blow Counts
Started: 3/1/2019
Carlsbad Phase III Recycled Water Project
Latitude: 33.111985°
Sheet 1 of 1
Project
Location: Center of Pad
Hour
Moisture Content (%)Visual ClassificationGroundwaterDepth (ft.)Surface Elevation:PenetrationResistance(Blows per 6 in.)Sample Taken376.0'
Reviewed By: G. Custenborder
Depth (ft)Other Tests
and Remarks
226816-0000111Completed: 3/1/2019
USCS Class.Dry Weight (pcf)Sample IDRig Type: CME-75 (BAJA)Date0
5
10
15
20
25
30
Logged By: S. BurfordHammer Efficiency: 71.2 %NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO - UPDATED.GLB \ CARLSBAD RW TANK - LOGS.GPJ
3.0'
12.0'
27.0'
7.6
8.3
9.8
5.5
6.3
7.2
7.1
7.2
7.2
25
35
37
50/5"
28
18
17
50/6"
37
50/5"
R-Value
Expansion Index
Atterberg Limits
Moisture Content
Moisture Content
Sieve Analysis
Maximum Density
Corrosivity
Moisture Content
Direct Shear
Moisture Content
Moisture Content
Moisture / Density
Moisture Content
Moisture Content
G- 1
SPT- 1
G- 2
MC- 1
SPT- 2
G- 3
MC- 2
G- 4
SPT- 3
SC
SC
SM
109.9
[TOPSOIL] Clayey SAND (SC): Brown, moist
[FORMATIONAL - Qvop] Clayey SAND (SC): Orange
brown, moist
Very Dense
Lenses of gray Bentonite (Clay)
Very Dense
[FORMATIONAL - Qvop] Silty SAND (SM): Orange brown,
moist, trace of clay
Dense
Very Dense
Very Dense
Traces of gravel
El. 372.0'
El. 363.0'
El. 348.0'
Notes: Drilled using a 6.5" O.D. Hollow Stem Auger. Boring terminated at depth of
27.0'. Groundwater not encountered. Backfilled with cuttings and bentonite
chips. Refusal in dense formational material.
Date
Graphical LogProject Number
Boring Log
B-2
Depth (ft.)Longitude: -117.286263°
Sample Type
Boring No.
Groundwater
G - Bulk / Grab SampleSPT - 2" O D. 1.4" I.D. Tube SampleMC - 3 " O.D. 2.4" I D. Ring SampleNR - No Recovery* - Uncorrected Blow Counts
Started: 3/1/2019
Carlsbad Phase III Recycled Water Project
Latitude: 33.111918°
Sheet 1 of 1
Project
Location: Edge of Pad
Hour
Moisture Content (%)Visual ClassificationGroundwaterDepth (ft.)Surface Elevation:PenetrationResistance(Blows per 6 in.)Sample Taken375.0'
Reviewed By: G. Custenborder
Depth (ft)Other Tests
and Remarks
226816-0000111Completed: 3/1/2019
USCS Class.Dry Weight (pcf)Sample IDRig Type: CME-75 (BAJA)Date0
5
10
15
20
25
Logged By: S. BurfordHammer Efficiency: 71.2 %NV5 GEOTECH (SD CQA) \ NV5 LIBRARY_SAN DIEGO - UPDATED.GLB \ CARLSBAD RW TANK - LOGS.GPJ
226818-0000111 NV5.COM |
APPENDIX B
Laboratory Test Results
226818-0000111 NV5.COM |
SUMMARY OF LABORATORY TEST RESULTS
In-situ Moisture and Density Tests
The in-situ moisture contents and dry densities of selected samples obtained from the test borings
were evaluated in general accordance with the latest version of D2216 and D2937 laboratory test
methods. The method involves obtaining the moist weight of the sample and then drying the sample
to obtain it’s dry weight. The moisture content is calculated by taking the difference between the wet
and dry weights, dividing it by the dry weight of the sample and expressing the result as a
percentage. The results of the in-situ moisture content and density tests are presented in the
following table and on the logs of exploratory borings in Appendix A.
RESULTS OF MOISTURE CONTENT AND DENSITY TESTS
(ASTM D2216 and ASTM D2937)
Sample Location Moisture Content (percent) Dry Density
(pounds per cubic foot)
Boring 1 @ 3 - 5 feet 9.7 Density Not Determined
Boring 1 @ 6 - 6.5 feet 11.8 115.8
Boring 1 @ 8 - 10 feet 11.8 Density Not Determined
Boring 1 @ 10 - 11.5 feet 8.5 Density Not Determined
Boring 1 @ 13 - 15 feet 3.3 Density Not Determined
Boring 1 @ 15 – 15.5 feet 7.1 110.8
Boring 1 @ 20 – 21.5 feet 8.6 Density Not Determined
Boring 1 @ 25 - 25.5 feet 8.1 104.5
Boring 1 @ 28 - 30 feet 9.1 Density Not Determined
Boring 2 @ 3 - 5 feet 7.6 Density Not Determined
Boring 2 @ 5 - 6.5 feet 8.3 Density Not Determined
Boring 2 @ 8 - 10 feet 9.8 Density Not Determined
Boring 2 @ 10 - 10.5 feet 5.5 109.9
Boring 2 @ 15 - 16.5 feet 6.3 Density Not Determined
Boring 2 @ 18 - 20 feet 7.2 Density Not Determined
Boring 2 @ 20 - 20.5 feet 7.1 103.8
Boring 2 @ 23 - 25 feet 7.2 Density Not Determined
Boring 2 @ 25 - 26 feet 7.2 Density Not Determined
226818-0000111 NV5.COM |
Classification
Soils were visually and texturally classified in general accordance with the Unified Soil Classification
System (ASTM D2487). Soil classifications are indicated on the logs of the exploratory borings
presented in Appendix A.
Particle-size Distribution Tests
An evaluation of the grain-size distribution of selected soil samples was performed in general
accordance with the latest version of ASTM D6913 (including –200 wash). These test results were
utilized in evaluating the soil classifications in accordance with the Unified Soil Classification System.
Particle size distribution test results are presented on the laboratory test sheets attached in this
appendix.
Atterberg Limits
Atterberg limits tests were performed in general accordance with ASTM D4318 on selected soil
samples. These tests were useful in classification of the soils. Test results are attached in this
appendix and summarized below.
RESULTS OF ATTERBERG LIMITS TESTS
(ASTM D4318)
Location B-1 @ 3 – 5 ft B-2 @ 3 – 5
Material
Type Clayey SAND (SC) Clayey SAND (SC)
Liquid Limit 26 26
Plastic Limit 15 13
Plasticity
Index 11 13
226818-0000111 NV5.COM |
Direct Shear
Direct shear tests were performed on representative relatively undisturbed samples in general
accordance with ASTM D3080 to evaluate the shear strength characteristics of the on-site materials.
The test method consists of placing the soil sample in the direct shear device, applying a series of
normal stresses, and then shearing the sample at the constant rate of shearing deformation. The
shearing force and horizontal displacements are measured and recorded as the soil specimen is
sheared. The shearing is continued well beyond the point of maximum stress until the stress reaches
a constant or residual value. The results of the tests are presented in the following table and attached
in this appendix.
RESULTS OF DIRECT SHEAR TESTS
(ASTM D3080)
Location USCS
Classification
Peak
Friction
(degrees)
Ultimate
Friction
(degrees)
Peak
Cohesion
(psf)
Ultimate
Cohesion
(psf)
Notes
Boring 1 @ 6 - 6.5 ft. SC 43 41 284 118 Relatively
undisturbed
Boring 2 @ 10 - 10.5 ft. SC 34 33 264 263 Relatively
undisturbed
Maximum Dry Density Tests
Maximum dry density testing was performed on samples of the on-site soils. The tests were
performed in general accordance with ASTM D1557. The results of the tests are presented below
and attached in this appendix.
RESULTS OF MAXIMUM DRY DENSITY TESTS
(ASTM D1557)
Location B-1 @ 3 – 5 ft B-2 @ 8 – 10 ft
Maximum Dry
Density 128.5 127.0
Optimum Moisture
Content 9.0 10.7
Material Type Clayey SAND (SC) Clayey SAND (SC)
226818-0000111 NV5.COM |
Resistance “R” Values Tests
An R-Value test was performed on a sample of the on-site soils. The test was performed in general
accordance with California Test Method 301/ ASTM D2844. The result of the test is presented
below and attached in this appendix.
RESULTS OF R-VALUE TESTS
(ASTM D2844 and CTM 301)
Location B-2 @ 3 – 5 ft
“R” Value 15
Material Type Clayey SAND (SC)
Expansion Index Tests
Expansion index tests were performed on samples of the on-site soils. The tests were performed in
general accordance with ASTM D4829. The result of the tests are presented below and attached in
this appendix.
RESULTS OF EXPANSION INDEX TESTS
(ASTM D4829)
Location Material Type
Initial
Moisture
Content,
%
Final
Moisture
Content,
%
Dry
Density,
pcf
Initial
Saturation,
%
Expansion
Index
Potential
Expansion
Boring 1
@ 3 - 5 ft.
Clayey
SAND (SC) 8.3 14.2 117.8 52.0 5 VERY
LOW
Boring 2
@ 3 - 5 ft.
Clayey
SAND (SC) 9.7 23.2 112.1 51.9 13 VERY
LOW
226818-0000111 NV5.COM |
Soil Corrosivity Tests
Water soluble sulfate, chloride, resistivity and pH tests were performed by Clarkson Laboratory and
Supply Inc., in general accordance with California Test Methods 417, 422 and 643 to provide an
indication of the degree of corrosivity of the subgrade soils at locations tested with regard to
concrete and normal grade steel.
RESULTS OF CORROSIVITY TESTS
(CTM 417, CTM 422 and CTM 643)
Sample Location B-1 @3 - 5 ft B-2 @8 - 10 ft
pH 7.6 5.9
Minimum Resistivity (Ohm-cm) 2100 1400
Water Soluble Sulfates (ppm) 54 33
Water Soluble Chlorides (ppm) 64 64
Material Type Clayey SAND
(SC)
Clayey SAND
(SC)
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental
Page1
Natural Moisture & Density Report
(ASTM D2216 & ASTM D2937)
Date:
March 26, 2019
Job Number:
226816-0000111
Client: Carlsbad Municipal Water District Report Number: 7182
Address: 5950 El Camino Real Lab Number: 117824, 117826-117832
Carlsbad, CA 92008 117833-117835
Project: Carlsbad Phase III Recycled Water Project 117837-117841
Project Add: Carlsbad, CA
Sampled By: Sean Burford
Date Sampled: 3/1/2019
Date Rcvd: 3/1/2019
Lab Number 117824 117826 117827 117828 117829
Exploration No. B1 B1 B1 B1 B1
Depth, ft. 3-5 8-10 10-11.5 13-15 15-15.5
Moisture Content, % 9.7 11.8 8.5 3.3 7.1
Dry Density, pcf - - - - 110.8
Lab Number 117830 117831 117832 117833 117834
Exploration No. B1 B1 B1 B2 B2
Depth, ft. 20-21.5 25-25.5 28-30 3-5 5-6.5
Moisture Content, % 8.6 8.1 9.1 7.6 8.3
Dry Density, pcf - 104.5 - - -
Lab Number 117835 117837 117838 117839 117840
Exploration No. B2 B2 B2 B2 B2
Depth, ft. 8-10 15-16.5 18-20 20-20.5 23-25
Moisture Content, % 9.8 6.3 7.2 7.1 7.2
Dry Density, pcf - - - 103.8 -
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental
Page2 Natural Moisture & Density Report
(ASTM D2216 & ASTM D2937)
Lab Number 117841
Exploration No. B2
Depth, ft. 25-26
Moisture Content, % 7.2
Dry Density, pcf -
Respectfully Submitted,
NV5 West, Inc.
Reviewed by:
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
Date:Job Number:226816-0000111
Client:Carlsbad Municipal Water District Report Number:7182
Address:5950 El Camino Real Lab Number:117824 & 117835
Carlsbad, CA 92008
Project :Carlsbad Phase III Recycled Water Project
Project Address:
Material
Color
Sample Location
Date Sampled
Date Submitted
Sampled By
Date Tested
Tested By
Sample ID:117824 117835
Sieve Size
76.2mm (3")100 100
63mm (2 1/2")100 100 Notes:Hardness: H&D = Hard & Durable; W&F = Weathered & Friable
50mm (2")100 100 N.R.: Not Recorded; N/A: Not Available.
37.5mm (1 1/2") 100 100
25mm (1")100 100
19mm (3/4")100 100
12.5mm (1/2") 100 100
9.5mm (3/8")100 100
4.75mm (#4) 100 100
2mm (#10)100 99
850µm (#20)95 97
425µm (#40)77 82
250µm (#60)53 60
150 µm (#100)39 48
75 um (#200) washµ29.6 42.1
Fineness Modulus 0 9 0.7 Respectfully Submitted,
Shape (sand & gravel)N.R.N.R.NV5 West, Inc.
Hardness (sand & gravel)N.R.H&D
Specific Gravity 2.65 2.65
Coef. of Curvature (CC)N.R.N.R.
Coef. of Uniformity (CU)N.R.N.R.
% Gravel 0 0
% Sand 70 58 Carl Henderson, PhD, PE, GE
% Fines 29.6 42.1 CQA Group Director (San Diego)
USCS Class:SC SC
B2 @ 8'-10'
% Passing
Edwin Ocampo
REPORT OF SIEVE ANALYSIS TEST
ASTM D6913 - Soil
Sean Burford Sean Burford
3/12/2019
3/1/2019
3/12/2019
Brown Orange Brown
117824 117835
3/1/2019
March 26, 2019
Carlsbad, CA
Clayey SAND (SC) Clayey SAND (SC)
3/1/2019 3/1/2019
B1 @ 3'-5'
Edwin Ocampo
0
10
20
30
40
50
60
70
80
90
100
0.010.1110100PERCENT FINER BY WEIGHTGRAIN SIZE (mm)
117824
117835
GRAVEL
coarse fine
SAND
coarse finemedium SILT or CLAYCBL
3/81/23/411.522.533.54 4 8 16 30 50 100 20040U.S. SIEVE OPENING (INCHES)U.S. SIEVE NUMBER HYDROMETER
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810
CQA - Infrastructure - Energy - Program Management - Environmental
Date:Job Number:
Client:Carlsbad Municipal Water District Report Number:
Address:5950 El Camino Real Lab Number:
Carlsbad Phase III Recycled Water Project
Project Address:Carlsbad, CA
Brown Clayey SAND (SC)
B1 @ 3'-5'
Date Sampled:
Date Submitted:
SUMMARY OF TEST RESULTS
TEST RESULT USCS
LL PL PI Class Group Name
117824 33 26 15 11 CL
Note:
Reviewed By:
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
%>#40
*For material passing the #40 sieve
*Sandy Lean CLAYB1 @ 3'-5'
SAMPLE ID
Project:
3/1/2019
Sampled By:
Date Tested:
March 26, 2019
Location:
(ASTM D4318)
Carlsbad, CA 92008
Material:
REPORT OF LIQUID LIMIT, PLASTIC LIMIT & PLASTICITY INDEX TESTS
3/1/2019
Sean Burford
3/11/2019
226816-0000111
7182
117824
SOURCE /LOCATION DEPTH
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110PLASTICITY INDEX (PI)LIQUID LIMIT (LL)
MH or OH
ML or OL
CH or OH
CL-ML “A ” Line “U ” Line CL or O
L 15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810
CQA - Infrastructure - Energy - Program Management - Environmental
Date:Job Number:
Client:Carlsbad Municipal Water District Report Number:
Address:5950 El Camino Real Lab Number:
Carlsbad Phase III Recycled Water Project
Project Address:Carlsbad, CA
Orange Brown Clayey SAND (SC)
B2 @ 3'-5'
Date Sampled:
Date Submitted:
SUMMARY OF TEST RESULTS
TEST RESULT USCS
LL PL PI Class Group Name
117833 NR 26 13 13 CL
Note:
Reviewed By:
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
*For material passing the #40 sieve
*Sandy Lean CLAYB2 @ 3'-5'
%>#40
REPORT OF LIQUID LIMIT, PLASTIC LIMIT & PLASTICITY INDEX TESTS
Material:
SOURCE /LOCATION DEPTHSAMPLE ID
Project:
3/1/2019
Sampled By:
Date Tested:
March 26, 2019
Location:
(ASTM D4318)
Carlsbad, CA 92008
3/1/2019
Sean Burford
3/11/2019
226816-0000111
7182
117833
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110PLASTICITY INDEX (PI)LIQUID LIMIT (LL)
MH or OH
ML or OL
CH or OH
CL-ML “A ” Line “U ” Line CL or O
L 15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810
CQA - Infrastructure - Energy - Program Management - Environmental
Project No.226816-0000111 Date:3/26/2019
Client:Carlsbad Municipal Water District Report No.:7182
Proj. Name:Lab No.:117825
Location:Carlsbad, CA Date Rcvd:3/1/2019
Sample date:3/1/2019 Sample Location:6'-6.5'Boring No.B1 Test Date:3/20/2019
TEST DATA:
.5 ksf 1 ksf 2 ksf
Water Content (%)11.8 11.8 11.8
Dry Density 115.8 113.1 120.0 Description:
Saturation (%)69.9 65.1 78.8
Water Content (%)15.4 15.8 14.6 Color:
Dry Density 111.7 109.3 114.4
Saturation (%)82.0 78.9 83.4
500 1000 2000
622 885 1893
861 1064 2219 Tested By:
Respectfully Submitted,
NV5 West, Inc.
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
Orange Brown
DIRECT SHEAR TEST (ASTM D3080)InitialFinalRelatively Undisturbed Sample
Clayey SAND (SC)
Sample ID:
Normal Stress (psf)
Sample Type:
Carlsbad Phase III Recycled Water
Peak Friction,Φ' (deg): 43
Peak Cohesion, C'(psf): 284
Ultimate Shear Stress (psf)
Peak Shear Stress (psf)
Ultimate Cohesion, C'(psf): 118
Ultimate Friction,Φ' (deg): 41
Darrel Delgado
NV5
15092 Avenue of Science, Ste 200
San Diego CA 92128
p. 858 385 0500 f. 858 715 5810
622
885
1893
861
1064
2219
y = 0.8703x + 118
y = 0.941x + 283.5
0
500
1000
1500
2000
2500
0 500 1000 1500 2000 2500Shear Stress, (psf)Effective Normal Stress, (psf)
Linear (Ultimate Strength
Envelope)
Linear (Peak Strength
Envelope)
Peak
Ultimate
0
500
1000
1500
2000
2500
0 0.05 0.1 0.15 0.2 0.25 0.3Shear Stress (psf)Horizontal Displacement (in)
.5 ksf
1 ksf
2 ksf
-0.005
0
0.005
0.01
0.015
0.02
0.025
0 0.05 0.1 0.15 0.2 0.25 0.3Vertical Displacement (in)Horizontal Displacement (in)
.5 ksf
1 ksf
2 ksf
Project No.226816-0000111 Date:3/26/2019
Client:Carlsbad Municipal Water District Report No.:7182
Proj. Name:Lab No.:117836
Location:Carlsbad, CA Date Rcvd:3/1/2019
Sample date:3/1/2019 Sample Location:10'-10.5'Boring No.B2 Test Date:3/22/2019
TEST DATA:
1 ksf 2 ksf 4 ksf
Water Content (%)5.5 5.5 5.5
Dry Density 109.9 113.8 111.7 Description:
Saturation (%)30.0 33.6 31.5
Water Content (%)13.4 11.9 11.8 Color:
Dry Density 103.1 109.2 106.2
Saturation (%)60.6 63.9 58.1
1000 2000 4000
808 1696 2786
820 1758 2870 Tested By:
Respectfully Submitted,
NV5 West, Inc.
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
Orange Brown
DIRECT SHEAR TEST (ASTM D3080)InitialFinalRelatively Undisturbed Sample
Clayey SAND (SC)
Sample ID:
Normal Stress (psf)
Sample Type:
Carlsbad Phase III Recycled Water
Peak Friction,Φ' (deg): 34
Peak Cohesion, C'(psf): 264
Ultimate Shear Stress (psf)
Peak Shear Stress (psf)
Ultimate Cohesion, C'(psf): 263
Ultimate Friction,Φ' (deg): 33
Darrel Delgado
NV5
15092 Avenue of Science, Ste 200
San Diego CA 92128
p. 858 385 0500 f. 858 715 5810
808
1696
2786
820
1758
2870
y = 0.643x + 263
y = 0.6651x + 264
0
500
1000
1500
2000
2500
3000
3500
4000
0 500 1000 1500 2000 2500 3000 3500 4000Shear Stress, (psf)Effective Normal Stress, (psf)
Linear (Ultimate Strength
Envelope)
Linear (Peak Strength
Envelope)
Peak
Ultimate
0
500
1000
1500
2000
2500
3000
3500
0 0.05 0.1 0.15 0.2 0.25 0.3Shear Stress (psf)Horizontal Displacement (in)
1 ksf
2 ksf
4 ksf
-0.03
-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
0 0.05 0.1 0.15 0.2 0.25 0.3Vertical Displacement (in)Horizontal Displacement (in)
1 ksf
2 ksf
4 ksf
Date:
Client:Carlsbad Municipal Water District
Client Address:5950 El Camino Real, Carlsbad, CA Job Number:226816-0000111
Project Name:Carlsbad Phase III Recycled Water Report Number:7182
Project Address:Carlsbad, CA Lab Number:117824
Date Sampled:03/01/19 Sampled By:Sean Burford
Date Submitted:03/01/19 Submitted By:Sean Burford
Sample Location:B1 @ 3'-5'Test Designation:ASTM_D1557
Material Description:Brown Clayey SAND (SC)Method:A
Material Source:NR Method of Sample Preparation:Moist
Oversize Correction?No Type of Hammer Used:Automatic
Sieve Results (Retained %):
3/4":0 3/8":0 #4:0
Respectfully Submitted,
NV5 West, Inc.128.5
9.0
Carl Henderson, PhD, PE, GE Maximum Density, pcf N/A
CQA Group Director (San Diego)N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
3/28/2019
SpGr = 2 6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810
CQA - Infrastructure - Energy - Program Management - Environmental
Date:
Client:Carlsbad Municipal Water District
Client Address:5950 El Camino Real, Carlsbad, CA Job Number:226816-0000111
Project Name:Carlsbad Phase III Recycled Water Report Number:7182
Project Address:Carlsbad, CA Lab Number:117835
Date Sampled:03/01/19 Sampled By:Sean Burford
Date Submitted:03/01/19 Submitted By:Sean Burford
Sample Location:B2 @ 8'-10'Test Designation:ASTM_D1557
Material Description:Orange Brown Clayey SAND (SC)Method:A
Material Source:NR Method of Sample Preparation:Moist
Oversize Correction?No Type of Hammer Used:Automatic
Sieve Results (Retained %):
3/4":0 3/8":0 #4:0
Respectfully Submitted,
NV5 West, Inc.127.0
10.7
Carl Henderson, PhD, PE, GE Maximum Density, pcf N/A
CQA Group Director (San Diego)N/A
Report of Moisture/Density Relationship Test
(ASTM D1557)
Optimum Moisture, %
Optimum Moisture, %
Maximum Density, pcf
Test Results
Oversize Corrected Results
3/28/2019
SpGr = 2 6
SpGr = 2.5
SpGr = 2.7
15092 Avenue of Science Suite 200 - San Diego, CA 92128 - www.NV5.com - Office 858.385.0500 - Fax 858.715.5810
CQA - Infrastructure - Energy - Program Management - Environmental
Date:Job Number:226816-0000111
Client:Carlsbad Municipal Water District Report Number:7182
Address:5950 El Camino Real Lab Number:117833
Carlsbad, CA 92008
Project :Carlsbad Phase III Recycled Water Project
Project Address :Carlsbad, CA
Material:Orange Brown Clayey SAND (SC)
Material Source:NR
Location:B2 @ 3'-5'
Sampled By:Sean Burford
Date Sampled:
Date Received:Tested By: Noah Regalado
Respectfully Submitted,
NV5 West, Inc.
Reviewed By:
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
3/1/2019
15R-VALUE AT EQUILIBRIUM
COMP. FOOT PRESSURE, psi
INITIAL MOISTURE %
MOISTURE @ COMPACTION %
DRY DENSITY, pcf
EXUDATION PRESSURE, psi
STABILOMETER VALUE 'R'
R-VALUE BY EXPANSION
15
122.2
3/1/2019
118.3
(CTM301 Caltrans / ASTM D2844)
0
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental
TEST SPECIMEN
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810
9
D
125.7
RESISTANCE "R" VALUE TEST
480
25
B
130
C
70
6.4
13.9
181
3/26/2019
R-VALUE BY EXUDATION
291
6.4
12.6
14
A
250
6.4
11.7
25
14
9
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
050100150200250300350400450500550600650700750800
Exudation Presure (psi)
EXUDATION PRESSURE CHART
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0 00.10 20 30.40 50.60.70 80 91 01.11 21 31.41 5Cover Thickness By Stabilometer,(ft)Cover Thickness by Expansion Pressure (ft)
EXPANSION PRESSURE CHART
15092 Avenue of Science Suite 200 | San Diego, CA 92128 | www.NV5.com | Office 858.385.0500 | Fax 858.715.5810
Construction Quality Assurance · Infrastructure · Energy · Program Management · Environmental
Expansion Index Test Report
(ASTM D4829)
Date:
March 26, 2019
Job Number:
226816-0000111
Client: Carlsbad Municipal Water District Report Number: 7182
Address: 5950 El Camino Real Lab Number: 117824 & 117833
Carlsbad, CA 92008
Project: Carlsbad Phase III Recycled Water Project
Project Add: Carlsbad, CA
Sampled By: Sean Burford
Date Sampled: 3/1/2019
Date Rcvd: 3/1/2019
Lab Number 117824 117833
Location B1 @ 3’-5’ B2 @ 3’-5’
Material Type Brown Clayey SAND
(SC)
Orange Brown Clayey
SAND (SC)
Initial Moisture Content, % 8.3 9.7
Final Moisture Content, % 14.2 23.2
Dry Density, pcf 117.8 112.1
Initial Saturation, % 52.0 51.9
Expansion Index 5 13
Potential Expansion VERY LOW VERY LOW
Respectfully Submitted,
NV5 West, Inc.
Carl Henderson, PhD, PE, GE
CQA Group Director (San Diego)
L A B O R A T O R Y R E P O R T
Telephone (619) 425-1993 Fax 425-7917 Established 1928
C L A R K S O N L A B O R A T O R Y A N D S U P P L Y I N C.
350 Trousdale Dr. Chula Vista, Ca. 91910 www.clarksonlab.com
A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S
Date: March 12, 2019
Purchase Order Number: 19-0450
Sales Order Number: 43579
Account Number: NV5-SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Brittani Escobedo
Laboratory Number: SO7226-1 Customers Phone: 858-715-5800
Fax: 858-715-5810
Sample Designation:
*-------------------------------------------------*
One soil sample received on 03/08/19 at 12:30pm,
from Phase 111 Recycled Water Project - Carlsbad Job#111,
phase 04, task 4.2 marked as Lab No 117824, Report# 7182,
B1, Depth 3-5.
Analysis By California Test 643, 1999, Department of Transportation
Division of Construction, Method for Estimating the Service Life of
Steel Culverts.
pH 7.6
Water Added (ml) Resistivity (ohm-cm)
10 7400
5 3400
5 2400
5 2500
5 2100
5 2200
5 2400
41 years to perforation for a 16 gauge metal culvert.
54 years to perforation for a 14 gauge metal culvert.
75 years to perforation for a 12 gauge metal culvert.
95 years to perforation for a 10 gauge metal culvert.
116 years to perforation for a 8 gauge metal culvert.
Water Soluble Sulfate Calif. Test 417 0.005 % (54ppm)
Water Soluble Chloride Calif. Test 422 0.006 % (64ppm)
__________________
Rosa Bernal
RMB/ilv
L A B O R A T O R Y R E P O R T
Telephone (619) 425-1993 Fax 425-7917 Established 1928
C L A R K S O N L A B O R A T O R Y A N D S U P P L Y I N C.
350 Trousdale Dr. Chula Vista, Ca. 91910 www.clarksonlab.com
A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S
Date: March 12, 2019
Purchase Order Number: 19-0450
Sales Order Number: 43579
Account Number: NV5-SD
To:
*-------------------------------------------------*
NV5 West Inc
15092 Avenue of Science #200
San Diego, CA 92128
Attention: Brittani Escobedo
Laboratory Number: SO7226-2 Customers Phone: 858-715-5800
Fax: 858-715-5810
Sample Designation:
*-------------------------------------------------*
One soil sample received on 03/08/19 at 12:30pm,
taken from Phase 111 Recycled Water Project - Carlsbad
Job#111, phase 04, task 4.2 marked as Lab No 117835,
Report# 7182, B2, Depth 8-10.
Analysis By California Test 643, 1999, Department of Transportation
Division of Construction, Method for Estimating the Service Life of
Steel Culverts.
pH 5.9
Water Added (ml) Resistivity (ohm-cm)
10 9500
5 3300
5 1600
5 1400
5 1400
5 1500
5 1600
13 years to perforation for a 16 gauge metal culvert.
17 years to perforation for a 14 gauge metal culvert.
24 years to perforation for a 12 gauge metal culvert.
30 years to perforation for a 10 gauge metal culvert.
37 years to perforation for a 8 gauge metal culvert.
Water Soluble Sulfate Calif. Test 417 0.003% (33ppm)
Water Soluble Chloride Calif. Test 422 0.006% (64ppm)
____________________
Rosa Bernal
RMB/ilv
226818-0000111 NV5.COM |
APPENDIX C
Typical Earthwork Guidelines
226818-0000111 NV5.COM |
TYPICAL EARTHWORK GUIDELINES
1. GENERAL
These guidelines and the standard details attached hereto are presented as general procedures for
earthwork construction for sites having slopes less than 10 feet high. They are to be utilized in
conjunction with the project grading plans. These guidelines are considered a part of the
geotechnical report, but are superseded by recommendations in the geotechnical report in the case
of conflict. Evaluations performed by the consultant during the course of grading may result in new
recommendations which could supersede these specifications and/or the recommendations of the
geotechnical report. It is the responsibility of the contractor to read and understand these guidelines
as well as the geotechnical report and project grading plans.
1.1. The contractor shall not vary from these guidelines without prior recommendations by the
geotechnical consultant and the approval of the client or the client's authorized
representative. Recommendations by the geotechnical consultant and/or client shall not
be considered to preclude requirements for approval by the jurisdictional agency prior to
the execution of any changes.
1.2. The contractor shall perform the grading operations in accordance with these
specifications, and shall be responsible for the quality of the finished product
notwithstanding the fact that grading work will be observed and tested by the
geotechnical consultant.
1.3. It is the responsibility of the grading contractor to notify the geotechnical consultant and
the jurisdictional agencies, as needed, prior to the start of work at the site and at any
time that grading resumes after interruption. Each step of the grading operations shall
be observed and documented by the geotechnical consultant and, where needed,
reviewed by the appropriate jurisdictional agency prior to proceeding with subsequent
work.
1.4. If, during the grading operations, geotechnical conditions are encountered which were
not anticipated or described in the geotechnical report, the geotechnical consultant shall
be notified immediately and additional recommendations, if applicable, may be provided.
1.5. An as-graded report shall be prepared by the geotechnical consultant and signed by a
registered engineer and registered engineering geologist. The report documents the
geotechnical consultants' observations, and field and laboratory test results, and
provides conclusions regarding whether or not earthwork construction was performed in
accordance with the geotechnical recommendations and the grading plans.
Recommendations for foundation design, pavement design, subgrade treatment, etc.,
may also be included in the as-graded report.
1.6. For the purpose of evaluating quantities of materials excavated during grading and/or
locating the limits of excavations, a licensed land surveyor or civil engineer shall be
retained.
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2. SITE PREPARATION
Site preparation shall be performed in accordance with the recommendations presented in the
following sections.
2.1. The client, prior to any site preparation or grading, shall arrange and attend a pre-grading
meeting between the grading contractor, the design engineer, the geotechnical
consultant, and representatives of appropriate governing authorities, as well as any other
involved parties. The parties shall be given two working days notice.
2.2. Clearing and grubbing shall consist of the substantial removal of vegetation, brush,
grass, wood, stumps, trees, tree roots greater than 1/2-inch in diameter, and other
deleterious materials from the areas to be graded. Clearing and grubbing shall extend to
the outside of the proposed excavation and fill areas.
2.3. Demolition in the areas to be graded shall include removal of building structures,
foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach
fields, seepage pits, cisterns, etc.), and other manmade surface and subsurface
improvements, and the backfilling of mining shafts, tunnels and surface depressions.
Demolition of utilities shall include capping or rerouting of pipelines at the project
perimeter, and abandonment of wells in accordance with the requirements of the
governing authorities and the recommendations of the geotechnical consultant at the
time of demolition.
2.4. The debris generated during clearing, grubbing and/or demolition operations shall be
removed from areas to be graded and disposed of off site at a legal dump site. Clearing,
grubbing, and demolition operations shall be performed under the observation of the
geotechnical consultant.
2.5. The ground surface beneath proposed fill areas shall be stripped of loose or unsuitable
soil. These soils may be used as compacted fill provided they are generally free of
organic or other deleterious materials and evaluated for use by the geotechnical
consultant. The resulting surface shall be evaluated by the geotechnical consultant prior
to proceeding. The cleared, natural ground surface shall be scarified to a depth of
approximately 8 inches, moisture conditioned, and compacted in accordance with the
specifications presented in Section 5 of these guidelines.
3. REMOVALS AND EXCAVATIONS
Removals and excavations shall be performed as recommended in the following sections.
3.1. Removals
3.1.1. Materials which are considered unsuitable shall be excavated under the
observation of the geotechnical consultant in accordance with the
recommendations contained herein. Unsuitable materials include, but may not
be limited to, dry, loose, soft, wet, organic, compressible natural soils, fractured,
weathered, soft bedrock, and undocumented or otherwise deleterious fill
materials.
226818-0000111 NV5.COM |
3.1.2. Materials deemed by the geotechnical consultant to be unsatisfactory due to
moisture conditions shall be excavated in accordance with the recommendations
of the geotechnical consultant, watered or dried as needed, and mixed to
generally uniform moisture content in accordance with the specifications
presented in Section 5 of this document.
3.2. Excavations
3.2.1. Temporary excavations no deeper than 4 feet in firm fill or natural materials may
be made with vertical side slopes. To satisfy California Occupational Safety and
Health Administration (CAL OSHA) requirements, any excavation deeper than
4 feet shall be shored or laid back at a 1:1 inclination or flatter, depending on
material type, if construction workers are to enter the excavation.
4. COMPACTED FILL
Fill shall be constructed as specified below or by other methods recommended by the geotechnical
consultant. Unless otherwise specified, fill soils shall be compacted to 90 percent relative
compaction, as evaluated in accordance with ASTM Test Method D1557.
4.1. Prior to placement of compacted fill, the contractor shall request an evaluation of the
exposed ground surface by the geotechnical consultant. Unless otherwise
recommended, the exposed ground surface shall then be scarified to a depth of
approximately 8 inches and watered or dried, as needed, to achieve a generally uniform
moisture content at or near the optimum moisture content. The scarified materials shall
then be compacted to 90 percent relative compaction. The evaluation of compaction by
the geotechnical consultant shall not be considered to preclude any requirements for
observation or approval by governing agencies. It is the contractor's responsibility to
notify the geotechnical consultant and the appropriate governing agency when project
areas are ready for observation, and to provide reasonable time for that review.
4.2. Excavated on-site materials which are in general compliance with the recommendations
of the geotechnical consultant may be utilized as compacted fill provided they are
generally free of organic or other deleterious materials and do not contain rock
fragments greater than 6 inches in dimension. During grading, the contractor may
encounter soil types other than those analyzed during the preliminary geotechnical study.
The geotechnical consultant shall be consulted to evaluate the suitability of any such
soils for use as compacted fill.
4.3. Where imported materials are to be used on site, the geotechnical consultant shall be
notified three working days in advance of importation in order that it may sample and
test the materials from the proposed borrow sites. No imported materials shall be
delivered for use on site without prior sampling, testing, and evaluation by the
geotechnical consultant.
226818-0000111 NV5.COM |
4.4. Soils imported for on-site use shall preferably have very low to low expansion potential
(based on UBC Standard 18-2 test procedures). Lots on which expansive soils may be
exposed at grade shall be undercut 3 feet or more and capped with very low to low
expansion potential fill. In the event expansive soils are present near the ground surface,
special design and construction considerations shall be utilized in general accordance
with the recommendations of the geotechnical consultant.
4.5. Fill materials shall be moisture conditioned to near optimum moisture content prior to
placement. The optimum moisture content will vary with material type and other factors.
Moisture conditioning of fill soils shall be generally uniform in the soil mass.
4.6. Prior to placement of additional compacted fill material following a delay in the grading
operations, the exposed surface of previously compacted fill shall be prepared to receive
fill. Preparation may include scarification, moisture conditioning, and recompaction.
4.7. Compacted fill shall be placed in horizontal lifts of approximately 8 inches in loose
thickness. Prior to compaction, each lift shall be watered or dried as needed to achieve
near optimum moisture condition, mixed, and then compacted by mechanical methods,
using sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other appropriate
compacting rollers, to the specified relative compaction. Successive lifts shall be treated
in a like manner until the desired finished grades are achieved.
4.8. Fill shall be tested in the field by the geotechnical consultant for evaluation of general
compliance with the recommended relative compaction and moisture conditions. Field
density testing shall conform to ASTM D1556-00 (Sand Cone method), D2937-00 (Drive-
Cylinder method), and/or D2922-96 and D3017-96 (Nuclear Gauge method). Generally,
one test shall be provided for approximately every 2 vertical feet of fill placed, or for
approximately every 1000 cubic yards of fill placed. In addition, on slope faces one or
more tests shall be taken for approximately every 10,000 square feet of slope face
and/or approximately every 10 vertical feet of slope height. Actual test intervals may
vary as field conditions dictate. Fill found to be out of conformance with the grading
recommendations shall be removed, moisture conditioned, and compacted or otherwise
handled to accomplish general compliance with the grading recommendations.
4.9. The contractor shall assist the geotechnical consultant by excavating suitable test pits for
removal evaluation and/or for testing of compacted fill.
4.10. At the request of the geotechnical consultant, the contractor shall "shut down" or restrict
grading equipment from operating in the area being tested to provide adequate testing
time and safety for the field technician.
4.11. The geotechnical consultant shall maintain a map with the approximate locations of field
density tests. Unless the client provides for surveying of the test locations, the locations
shown by the geotechnical consultant will be estimated. The geotechnical consultant
shall not be held responsible for the accuracy of the horizontal or vertical locations or
elevations.
226818-0000111 NV5.COM |
4.12. Grading operations shall be performed under the observation of the geotechnical
consultant. Testing and evaluation by the geotechnical consultant does not preclude the
need for approval by or other requirements of the jurisdictional agencies.
4.13. Fill materials shall not be placed, spread or compacted during unfavorable weather
conditions. When work is interrupted by heavy rains, the filling operation shall not be
resumed until tests indicate that moisture content and density of the fill meet the project
specifications. Regrading of the near-surface soil may be needed to achieve the
specified moisture content and density.
4.14. Upon completion of grading and termination of observation by the geotechnical
consultant, no further filling or excavating, including that planned for footings,
foundations, retaining walls or other features, shall be performed without the
involvement of the geotechnical consultant.
4.15. Fill placed in areas not previously viewed and evaluated by the geotechnical consultant
may have to be removed and recompacted at the contractor's expense. The depth and
extent of removal of the unobserved and undocumented fill will be decided based upon
review of the field conditions by the geotechnical consultant.
4.16. Off-site fill shall be treated in the same manner as recommended in these specifications
for on-site fills. Off-site fill subdrains temporarily terminated (up gradient) shall be
surveyed for future locating and connection.
5. OVERSIZED MATERIAL
Oversized material shall be placed in accordance with the following recommendations.
5.1. During the course of grading operations, rocks or similar irreducible materials greater
than 6 inches in dimension (oversized material) may be generated. These materials shall
not be placed within the compacted fill unless placed in general accordance with the
recommendations of the geotechnical consultant.
5.2. Where oversized rock (greater than 6 inches in dimension) or similar irreducible material
is generated during grading, it is recommended, where practical, to waste such material
off site, or on site in areas designated as "nonstructural rock disposal areas." Rock
designated for disposal areas shall be placed with sufficient sandy soil to generally fill
voids. The disposal area shall be capped with a 5-foot thickness of fill which is generally
free of oversized material.
5.3. Rocks 6 inches in dimension and smaller may be utilized within the compacted fill,
provided they are placed in such a manner that nesting of rock is not permitted. Fill shall
be placed and compacted over and around the rock. The amount of rock greater than
¾-inch in dimension shall generally not exceed 40 percent of the total dry weight of the
fill mass, unless the fill is specially designed and constructed as a "rock fill."
226818-0000111 NV5.COM |
5.4. Rocks or similar irreducible materials greater than 6 inches but less than 4 feet in
dimension generated during grading may be placed in windrows and capped with finer
materials in accordance with the recommendations of the geotechnical consultant and
the approval of the governing agencies. Selected native or imported granular soil (Sand
Equivalent of 30 or higher) shall be placed and flooded over and around the windrowed
rock such that voids are filled. Windrows of oversized materials shall be staggered so
that successive windrows of oversized materials are not in the same vertical plane.
Rocks greater than 4 feet in dimension shall be broken down to 4 feet or smaller before
placement, or they shall be disposed of off site.
6. SLOPES
The following sections provide recommendations for cut and fill slopes.
6.1. Cut Slopes
6.1.1. The geotechnical consultant shall observe cut slopes during excavation. The
geotechnical consultant shall be notified by the contractor prior to beginning
slope excavations.
6.1.2. If, during the course of grading, adverse or potentially adverse geotechnical
conditions are encountered in the slope which were not anticipated in the
preliminary evaluation report, the geotechnical consultant shall evaluate the
conditions and provide appropriate recommendations.
6.2. Fill Slopes
6.2.1. When placing fill on slopes steeper than 5:1 (horizontal:vertical), topsoil, slope
wash, colluvium, and other materials deemed unsuitable shall be removed.
Near-horizontal keys and near-vertical benches shall be excavated into sound
bedrock or fine fill material, in accordance with the recommendation of the
geotechnical consultant. Keying and benching shall be accomplished.
Compacted fill shall not be placed in an area subsequent to keying and benching
until the area has been observed by the geotechnical consultant. Where the
natural gradient of a slope is less than 5:1, benching is generally not
recommended. However, fill shall not be placed on compressible or otherwise
unsuitable materials left on the slope face.
6.2.2. Within a single fill area where grading procedures dictate two or more separate
fills, temporary slopes (false slopes) may be created. When placing fill adjacent
to a temporary slope, benching shall be conducted in the manner described in
Section 7.2. A 3-foot or higher near-vertical bench shall be excavated into the
documented fill prior to placement of additional fill.
6.2.3. Unless otherwise recommended by the geotechnical consultant and accepted by
the Building Official, permanent fill slopes shall not be steeper than 2:1
(horizontal:vertical). The height of a fill slope shall be evaluated by the
geotechnical consultant.
226818-0000111 NV5.COM |
6.2.4. Unless specifically recommended otherwise, compacted fill slopes shall be
overbuilt and cut back to grade, exposing firm compacted fill. The actual amount
of overbuilding may vary as field conditions dictate. If the desired results are not
achieved, the existing slopes shall be overexcavated and reconstructed in
accordance with the recommendations of the geotechnical consultant. The
degree of overbuilding may be increased until the desired compacted slope face
condition is achieved. Care shall be taken by the contractor to provide
mechanical compaction as close to the outer edge of the overbuilt slope surface
as practical.
6.2.5. If access restrictions, property line location, or other constraints limit overbuilding
and cutting back of the slope face, an alternative method for compaction of the
slope face may be attempted by conventional construction procedures including
backrolling at intervals of 4 feet or less in vertical slope height, or as dictated by
the capability of the available equipment, whichever is less. Fill slopes shall be
backrolled utilizing a conventional sheepsfoot-type roller. Care shall be taken to
maintain the specified moisture conditions and/or reestablish the same, as
needed, prior to backrolling.
6.2.6. The placement, moisture conditioning and compaction of fill slope materials shall
be done in accordance with the recommendations presented in Section 5 of
these guidelines.
6.2.7. The contractor shall be ultimately responsible for placing and compacting the soil
out to the slope face to obtain a relative compaction of 90 percent as evaluated
by ASTM D1557 and a moisture content in accordance with Section 5. The
geotechnical consultant shall perform field moisture and density tests at intervals
of one test for approximately every 10,000 square feet of slope.
6.2.8. Backdrains shall be provided in fill as recommended by the geotechnical
consultant.
6.3. Top-of-Slope Drainage
6.3.1. For pad areas above slopes, positive drainage shall be established away from the
top of slope. This may be accomplished utilizing a berm and pad gradient of
2 percent or steeper at the top-of-slope areas. Site runoff shall not be permitted
to flow over the tops of slopes.
6.3.2. Gunite-lined brow ditches shall be placed at the top of cut slopes to redirect
surface runoff away from the slope face where drainage devices are not
otherwise provided.
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6.4. Slope Maintenance
6.4.1. In order to enhance surficial slope stability, slope planting shall be accomplished
at the completion of grading. Slope plants shall consist of deep-rooting, variable
root depth, drought-tolerant vegetation. Native vegetation is generally desirable.
Plants native to semiarid and mid areas may also be appropriate. Large-leafed
ice plant should not be used on slopes. A landscape architect shall be consulted
regarding the actual types of plants and planting configuration to be used.
6.4.2. Irrigation pipes shall be anchored to slope faces and not placed in trenches
excavated into slope faces. Slope irrigation shall be maintained at a level just
sufficient to support plant growth. Property owners shall be made aware that
over watering of slopes is detrimental to slope stability. Slopes shall be
monitored regularly and broken sprinkler heads and/or pipes shall be repaired
immediately.
6.4.3. Periodic observation of landscaped slope areas shall be planned and appropriate
measures taken to enhance growth of landscape plants.
6.4.4. Graded swales at the top of slopes and terrace drains shall be installed and the
property owners notified that the drains shall be periodically checked so that they
may be kept clear. Damage to drainage improvements shall be repaired
immediately. To reduce siltation, terrace drains shall be constructed at a
gradient of 3 percent or steeper, in accordance with the recommendations of the
project civil engineer.
6.4.5. If slope failures occur, the geotechnical consultant shall be contacted
immediately for field review of site conditions and development of
recommendations for evaluation and repair.
7. TRENCH BACKFILL
The following sections provide recommendations for backfilling of trenches.
7.1. Trench backfill shall consist of granular soils (bedding) extending from the trench bottom
to 1 foot or more above the pipe. On-site or imported fill which has been evaluated by
the geotechnical consultant may be used above the granular backfill. The cover soils
directly in contact with the pipe shall be classified as having a very low expansion
potential, in accordance with UBC Standard 18-2, and shall contain no rocks or chunks of
hard soil larger than 3/4-inch in diameter.
7.2. Trench backfill shall, unless otherwise recommended, be compacted by mechanical
means to 90 percent relative compaction as evaluated by ASTM D1557. Backfill soils
shall be placed in loose lifts 8-inches thick or thinner, moisture conditioned, and
compacted in accordance with the recommendations of Section 5 of these guidelines.
The backfill shall be tested by the geotechnical consultant at vertical intervals of
approximately 2 feet of backfill placed and at spacings along the trench of approximately
100 feet in the same lift.
226818-0000111 NV5.COM |
7.3. Jetting of trench backfill materials is generally not a recommended method of
densification, unless the on-site soils are sufficiently free-draining and provisions have
been made for adequate dissipation of the water utilized in the jetting process.
7.4. If it is decided that jetting may be utilized, granular material with a sand equivalent
greater than 30 shall be used for backfilling in the areas to be jetted. Jetting shall
generally be considered for trenches 2 feet or narrower in width and 4 feet or shallower
in depth. Following jetting operations, trench backfill shall be mechanically compacted to
the specified compaction to finish grade.
7.5. Trench backfill which underlies the zone of influence of foundations shall be
mechanically compacted to 90 percent or greater relative compaction, as evaluated by
ASTM D1557. The zone of influence of the foundations is generally defined as the
roughly triangular area within the limits of a 1:1 (horizontal:vertical) projection from the
inner and outer edges of the foundation, projected down and out from both edges.
7.6. Trench backfill within slab areas shall be compacted by mechanical means to a relative
compaction of 90 percent, as evaluated by ASTM D1557. For minor interior trenches,
density testing may be omitted or spot testing may be performed, as deemed appropriate
by the geotechnical consultant.
7.7. When compacting soil in close proximity to utilities, care shall be taken by the grading
contractor so that mechanical methods used to compact the soils do not damage the
utilities. If the utility contractors indicate that it is undesirable to use compaction
equipment in close proximity to a buried conduit, then the grading contractor may elect
to use light mechanical compaction equipment or, with the approval of the geotechnical
consultant, cover the conduit with clean granular material. These granular materials
shall be jetted in place to the top of the conduit in accordance with the recommendations
of Section 8.4 prior to initiating mechanical compaction procedures. Other methods of
utility trench compaction may also be appropriate, upon review by the geotechnical
consultant and the utility contractor, at the time of construction.
7.8. Clean granular backfill and/or bedding materials are not recommended for use in slope
areas unless provisions are made for a drainage system to mitigate the potential for
buildup of seepage forces or piping of backfill materials.
7.9. The contractor shall exercise the specified safety precautions, in accordance with OSHA
Trench Safety Regulations, while conducting trenching operations. Such precautions
include shoring or laying back trench excavations at 1:1 or flatter, depending on material
type, for trenches in excess of 5 feet in depth. The geotechnical consultant is not
responsible for the safety of trench operations or stability of the trenches.
226818-0000111 NV5.COM |
8. DRAINAGE
The following sections provide recommendations pertaining to site drainage.
8.1. Roof, pad, and slope drainage shall be such that it is away from slopes and structures to
suitable discharge areas by nonerodible devices (e.g., gutters, downspouts, concrete
swales, etc.).
8.2. Positive drainage adjacent to structures shall be established and maintained. Positive
drainage may be accomplished by providing drainage away from the foundations of the
structure at a gradient of 2 percent or steeper for a distance of 5 feet or more outside
the building perimeter, further maintained by a graded swale leading to an appropriate
outlet, in accordance with the recommendations of the project civil engineer and/or
landscape architect.
8.3. Surface drainage on the site shall be provided so that water is not permitted to pond. A
gradient of 2 percent or steeper shall be maintained over the pad area and drainage
patterns shall be established to remove water from the site to an appropriate outlet.
8.4. Care shall be taken by the contractor during grading to preserve any berms, drainage
terraces, interceptor swales or other drainage devices of a permanent nature on or
adjacent to the property. Drainage patterns established at the time of finish grading
shall be maintained for the life of the project. Property owners shall be made very clearly
aware that altering drainage patterns may be detrimental to slope stability and
foundation performance.
9. SITE PROTECTION
The site shall be protected as outlined in the following sections.
9.1. Protection of the site during the period of grading shall be the responsibility of the
contractor unless other provisions are made in writing and agreed upon among the
concerned parties. Completion of a portion of the project shall not be considered to
preclude that portion or adjacent areas from the need for site protection, until such time
as the project is finished as agreed upon by the geotechnical consultant, the client, and
the regulatory agency.
9.2. The contractor is responsible for the stability of temporary excavations.
Recommendations by the geotechnical consultant pertaining to temporary excavations
are made in consideration of stability of the finished project and, therefore, shall not be
considered to preclude the responsibilities of the contractor. Recommendations by the
geotechnical consultant shall also not be considered to preclude more restrictive
requirements by the applicable regulatory agencies.
9.3. Precautions shall be taken during the performance of site clearing, excavation, and
grading to protect the site from flooding, ponding, or inundation by surface runoff.
Temporary provisions shall be made during the rainy season so that surface runoff is
away from and off the working site. Where low areas cannot be avoided, pumps shall be
provided to remove water as needed during periods of rainfall.
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9.4. During periods of rainfall, plastic sheeting shall be used as needed to reduce the
potential for unprotected slopes to become saturated. Where needed, the contractor
shall install check dams, desilting basins, riprap, sandbags or other appropriate devices
or methods to reduce erosion and provide recommended conditions during inclement
weather.
9.5. During periods of rainfall, the geotechnical consultant shall be kept informed by the
contractor of the nature of remedial or precautionary work being performed on site (e.g.,
pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.).
9.6. Following periods of rainfall, the contractor shall contact the geotechnical consultant and
arrange a walk-over of the site in order to visually assess rain-related damage. The
geotechnical consultant may also recommend excavation and testing in order to aid in
the evaluation. At the request of the geotechnical consultant, the contractor shall make
excavations in order to aid in evaluation of the extent of rain-related damage.
9.7. Rain or irrigation related damage shall be considered to include, but may not be limited
to, erosion, silting, saturation, swelling, structural distress, and other adverse conditions
noted by the geotechnical consultant. Soil adversely affected shall be classified as
"Unsuitable Material" and shall be subject to overexcavation and replacement with
compacted fill or to other remedial grading as recommended by the geotechnical
consultant.
9.8. Relatively level areas where saturated soils and/or erosion gullies exist to depths greater
than 1 foot shall be overexcavated to competent materials as evaluated by the
geotechnical consultant. Where adverse conditions extend to less than 1 foot in depth,
saturated and/or eroded materials may be processed in-place. Overexcavated or in-
place processed materials shall be moisture conditioned and compacted in accordance
with the recommendations provided in Section 5. If the desired results are not achieved,
the affected materials shall be overexcavated, moisture conditioned, and compacted
until the specifications are met.
9.9. Slope areas where saturated soil and/or erosion gullies exist to depths greater than 1
foot shall be overexcavated and replaced as compacted fill in accordance with the
applicable specifications. Where adversely affected materials exist to depths of I foot or
less below proposed finished grade, remedial grading by moisture conditioning in-place
and compaction in accordance with the appropriate specifications may be attempted. If
the desired results are not achieved, the affected materials shall be overexcavated,
moisture conditioned, and compacted until the specifications are met. As conditions
dictate, other slope repair procedures may also be recommended by the geotechnical
consultant.
9.10. During construction, the contractor shall grade the site to provide positive drainage away
from structures and to keep water from ponding adjacent to structures. Water shall not
be allowed to damage adjacent properties. Positive drainage shall be maintained by the
contractor until permanent drainage and erosion reducing devices are installed in
accordance with project plans.
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APPENDIX D
GBA - Important Information About This Geotechnical Report
Geotechnical-Engineering Report
Important Information about This
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, clients can benefit from a lowered exposure to the subsurface problems that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed below, contact your GBA-member geotechnical engineer. Active involvement in the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project.
Geotechnical-Engineering Services Are Performed for Specific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Those who rely on a geotechnical-engineering report prepared for a different client can be seriously misled. No one except authorized client representatives should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one – not even you – should apply this report for any purpose or project except the one originally contemplated.
Read this Report in FullCostly problems have occurred because those relying on a geotechnical-engineering report did not read it in its entirety. Do not rely on an executive summary. Do not read selected elements only. Read this report in full.
You Need to Inform Your Geotechnical Engineer about ChangeYour geotechnical engineer considered unique, project-specific factors when designing the study behind this report and developing the confirmation-dependent recommendations the report conveys. A few typical factors include: • the client’s goals, objectives, budget, schedule, and risk-management preferences; • the general nature of the structure involved, its size, configuration, and performance criteria; • the structure’s location and orientation on the site; and • other planned or existing site improvements, such as retaining walls, access roads, parking lots, and underground utilities.
Typical changes that could erode the reliability of this report include
those that affect:
• the site’s size or shape;
• the function of the proposed structure, as when it’s
changed from a parking garage to an office building, or
from a light-industrial plant to a refrigerated warehouse;
• the elevation, configuration, location, orientation, or
weight of the proposed structure;
• the 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. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered.
This Report May Not Be ReliableDo not rely on this report if your geotechnical engineer prepared it:
• for a different client;
• for a different project;
• for a different site (that may or may not include all or a
portion of the original site); or
• before important events occurred at the site or adjacent
to it; e.g., man-made events like construction or
environmental remediation, or natural events like floods,
droughts, earthquakes, or groundwater fluctuations.
Note, too, that it could be unwise to rely on a geotechnical-engineering
report whose reliability may have been affected by the passage of time,
because of factors like changed subsurface conditions; new or modified
codes, standards, or regulations; or new techniques or tools. If your geotechnical engineer has not indicated an “apply-by” date on the report, ask what it should be, and, in general, if you are the least bit uncertain
about the continued reliability of this report, contact your geotechnical
engineer before applying it. A minor amount of additional testing or
analysis – if any is required at all – could prevent major problems.
Most of the “Findings” Related in This Report Are Professional Opinions
Before construction begins, geotechnical engineers explore a site’s
subsurface through various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing were performed. The
data derived from that sampling and testing were reviewed by your
geotechnical engineer, who then applied professional judgment to
form opinions about subsurface conditions throughout the site. Actual
sitewide-subsurface conditions may differ – maybe significantly – from
those indicated in this report. Confront that risk by retaining your
geotechnical engineer to serve on the design team from project start to
project finish, so the individual can provide informed guidance quickly,
whenever needed.
This Report’s Recommendations Are Confirmation-DependentThe recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgment and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions revealed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation.
This Report Could Be MisinterpretedOther design professionals’ misinterpretation of geotechnical-engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a full-time member of the design team, to: • confer with other design-team members, • help develop specifications, • review pertinent elements of other design professionals’ plans and specifications, and • be on hand quickly whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction observation.
Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for informational purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report, but they may rely on the factual data relative to the specific times, locations, and depths/elevations referenced. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may
perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position
to give constructors the information available to you, while requiring
them to at least share some of the financial responsibilities stemming
from unanticipated conditions. Conducting prebid and preconstruction
conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. That lack of understanding has nurtured
unrealistic expectations that have resulted in disappointments, delays,
cost overruns, claims, and disputes. To confront that risk, geotechnical
engineers commonly include explanatory provisions in their reports.
Sometimes labeled “limitations,” many of these provisions indicate
where geotechnical engineers’ responsibilities 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.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
environmental study – e.g., a “phase-one” or “phase-two” environmental
site assessment – differ significantly from those used to perform
a geotechnical-engineering study. For that reason, a geotechnical-
engineering report does not usually relate any environmental findings,
conclusions, or recommendations; e.g., about the likelihood of
encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not yet obtained your own environmental
information, ask your geotechnical consultant for risk-management
guidance. As a general rule, do not rely on an environmental report prepared for a different client, site, or project, or that is more than six months old.
Obtain Professional Assistance to Deal with Moisture Infiltration and Mold
While your geotechnical engineer may have addressed groundwater,
water infiltration, or similar issues in this report, none of the engineer’s
services were designed, conducted, or intended to prevent uncontrolled
migration of moisture – including water vapor – from the soil through
building slabs and walls and into the building interior, where it can
cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront
the risk of moisture infiltration by including building-envelope or mold
specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists.
Copyright 2016 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly
prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent
Telephone: 301/565-2733
e-mail: info@geoprofessional.org www.geoprofessional.org
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