HomeMy WebLinkAboutCT 00-16; Poinsettia Properties; Geotechnical Investigation; 2001-10-16GEOTECHNICAL INVESTIGATION
POINSETTIA PROPERTIES
SEWER PUMP STATION
CARLSBAD, CALIFORNIA
Kr'"
PREPARED FOR
JOHN LAING HOMES
NEWPORT BEACH, CALIFORNIA
OCTOBER 16, 2001
GEOCON
INCORPORATED
Project No. 06514-52-03
October 16, 2001
John Laing Homes
895 Dove Street, Suite 110
Newport Beach, California 92660
Attention: Mr. Pablo Leon
Subject:POINSETTIA PROPERTIES
SEWER PUMP STATION
CARLSBAD, CALIFORNIA
GEOTECHNICAL INVESTIGATION
GEOTECHNICAL CONSULTANTS
Gentlemen:
In accordance with your request and authorization of our proposal dated September 17, 2001
(Proposal No. LG-01474), we have performed a geotechnical investigation for the subject project.
The accompanying report presents the findings of our study and the conclusions and
recommendations based on those findings.
Geotechnical considerations related to shallow groundwater will impact the design and construction
of the project, however, the site may be developed as proposed, provided the recommendations of this
report are followed.
If you have any questions regarding this report, or if we may be of further service, please do not
hesitate to contact the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
CEG 1778
AS:KPA:dlj
(6) Addressee
(3/del) Nolte & Associates
Attention: Mr. Cark Sepponen
(2/del) Project Design Consultants
Attention: Mr. Curtis Turner
#1778
. , CERTIFIED
* l ENGINEERING
6960 Flanders Drive • San Diego, California 92121-2974 • Telephone (858) 558-6900 • Fax (858) 558-6159
TABLE OF CONTENTS
1. PURPOSE AND SCOPE 1
2. SITE AND PROJECT DESCRIPTION 1
3. SOIL AND GEOLOGIC CONDITIONS 2
3.1 Topsoils (Unmapped) 2
3.2 Alluvium (Qal) 2
3.3 Terrace Deposits (Qt) 2
3.4 Santiago Formation (Tsa) 3
4. GROUNDWATER 3
5. GEOLOGIC HAZARDS 3
5.1 Faulting and Seismiciry 3
5.2 Liquefaction 4
6. CONCLUSIONS AND RECOMMENDATIONS 5
6.1 General 5
6.2 Excavation Characteristics and Dewatering 5
6.3 Corrosion 6
6.4 Grading 7
6.5 Seismic Design Criteria 8
6.6 Foundations-Generator and Transformer Buildings 8
6.7 Foundation-Pump Structure 9
6.8 Lateral Earth Pressures-Retaining Walls 9
6.9 Lateral Earth Pressures-Main Structure 10
6.10 Lateral Load Resistance '. 11
6.11 Site Drainage 11
6.12 Foundation and Grading Plan Review 11
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Site Plan
APPENDIX A
FIELD INVESTIGATION
Figure A-l-A-2, Logs of Borings
APPENDIX B
LABORATORY TESTING
Table B-I, Summary of Laboratory Maximum Dry Density Optimum Moisture
Content Test Results
Table B-E, Summary of Laboratory Water-Soluble Sulfate Test Results
Figure B-l and B-2, Gradation Curves
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of a geotechnical investigation for the proposed Poinsettia Properties
Sewer Pump Station located in Carlsbad, California (see Vicinity Map, Figure 1). The purpose of the
investigation was to evaluate the surface and subsurface soil and geologic conditions at the site, and
based on the conditions encountered, provide recommendations pertaining to the geotechnical aspects
of developing the pump station site as presently proposed. Specific geotechnical parameters required
for design were provided to us via facsimile prepared by Nolte & Associates dated October 5, 2001.
The scope of the field investigation included a geologic site reconnaissance, advancing one exploratory
boring, and sampling the subsurface soils. Due to existing underground utilities, the exploratory boring
was performed just east of the proposed pump station footprint. Additionally, a review of aerial
photographs and relevant soil and geological literature concerning the site was performed. This
included a review of the geotechnical investigation report for the Poinsettia Properties project entitled
Update Geotechnical Investigation, Poinsettia Property, Carlsbad, California, prepared by Geocon
Incorporated, dated July 20, 2000, and the plans entitled Grading and Erosion Control Plans for
Poinsettia Properties, Planning Areas 2, 3 & 4, prepared by Project Design Consultants, progress print
dated August 20, 2001.
Laboratory tests were performed on selected soil samples obtained at various depths in the exploratory
boring to evaluate pertinent physical properties. Details of the field investigation and laboratory tests
are presented in Appendices A and B, respectively. The recommendations presented herein are based
on an analysis of the data obtained from the exploratory boring, laboratory tests, information obtained
from the above referenced investigation report dated July 20, 2000, and our experience with similar soil
and geologic conditions.
2. SITE AND PROJECT DESCRIPTION
The proposed pump station will be constructed on Lot 225 of the Poinsettia Properties project, a
residential development of approximately 220 single-family homes, located north of Poinsettia Lane and
west of Avenida Encinas in Carlsbad, California (see Vicinity Map, Figure 1). Specifically, Lot 225 is
within the southwestern-most corner of the project, adjacent to Poinsettia Lane. The pump station will
consist of a concrete/masonry building which houses the wet well, electrical/mechanical equipment, and
associated sewer mains (see Figure 2, Site Plan).
Project No. 06514-52-03 - 1 - October 16,2001
The lowest part of the structure (wet well) will be located at approximately 30 feet below existing grade.
Limited grading is anticipated for the building pad however, some cut/fill may be required for the
surrounding improvements.
The locations and descriptions contained herein are based upon a site reconnaissance and the Site Plan
referenced above. If project details vary significantly from those outlined, Geocon Incorporated should
be notified for review and possible revision of the recommendations presented herein prior to final
design submittal.
3. SOIL AND GEOLOGIC CONDITIONS
Two surficial soil types and two formational units were encountered during our field investigation. The
surficial units consist of topsoils and alluvial soils and is underlain by formational soils consisting of
Terrace Deposits and the Santiago Formation as discussed below. The approximate lateral extent of the
geologic units is presented on Figure 3, Geologic Map.
3.1 Topsoils (Unmapped)
Topsoils consisting of loose, dry to moist, fine silty sand and sandy silt cover the area of Lot 225. The
topsoils average 2 to 3 feet in thickness and generally exhibit low expansion characteristics. Removal
and recompaction of topsoils will be required in areas to receive settlement sensitive structures.
3.2 Alluvium (Qal)
Alluvial soils were found at the surface within the eastern portion of Lot 224 and extending to a depth
within the exploratory boring of approximately 4 feet. These soils are characterized as loose to medium
dense, moist to saturated, brown, clayey to silty sand and sandy clay to silt. Due to the unconsolidated
condition, alluvial soils are potentially compressible when subjected to an increase in loading. All
alluvial soils should be removed and replaced with compacted fill in areas of planned development. The
proposed pump station however, is located within Lot 225, west of the contact between alluvium and
the Terrace Deposits. The proposed pump station is not located in an area where alluvium is mapped.
3.3 Terrace Deposits (Qt)
Underlying the alluvial soils in Lot 224 and below the topsoil within Lot 225 is dense Quaternary-age
Terrace Deposits. The deposits encountered consist of fine- to medium-grained sand with some clay.
The Terrace Deposits in their present condition are suitable for support of compacted fill soils and loads
from the proposed development.
Project No. 06514-52-03 - 2 - October 16, 2001
3.4 Santiago Formation (Tsa)
The Tertiary-age Santiago Formation is present below the Terrace Deposits at a depth on the order of
25 feet below the existing ground surface. The formation as encountered consists of dense to very
dense, fine- to medium-grained sand with some clay and traces of silt. The Santiago Formation is
suitable for support of compacted fill soils and loads from the proposed development.
4. GROUNDWATER
Groundwater was encountered in the exploratory boring at a depth of approximately 13 feet below the
existing ground surface. Groundwater will have a significant impact on the design and construction of
the pump station. The contractor will likely have to implement an appropriate dewatering system.
Furthermore, a buoyancy factor, hydraulic head pressure, and the use of an appropriate waterproof
sealant/coating will be a consideration in the design of the structures anticipated to be below the water
table.
5. GEOLOGIC HAZARDS
5.1 Faulting and Seismicity
Based on our reconnaissance, and a review of published geologic maps and reports, the site is not
located on any known active or potentially active fault trace. The nearest known active fault is the
northern extension of the Rose Canyon Fault located approximately 4 miles to the west. Major
earthquakes occurring on the Rose Canyon Fault, or other regional active faults located in the southern
California area, could subject the site to moderate-to-severe ground shaking within the life span of the
proposed structures.
In order to determine the distance of known faults to the site, the computer program EQFAULT (Blake,
2000) was utilized. In addition to fault location, EQFAULT was used to estimate ground accelerations
at the site for the maximum credible and maximum probable seismic events. Attenuation relationships
presented by Sadigh et al. (1997) were used in the analysis to estimate site accelerations.
The results of the deterministic analysis indicate that the Rose Canyon Fault zone, the Offshore Zone of
Deformation, and Coronado Banks Fault Zone are among the dominant sources for potential ground
motion occurring at the site. The "maximum credible earthquake" is defined as the maximum
earthquake that appears capable of occurring under the presently known tectonic framework (California
Division of Mines and Geology Notes, Number 43). The estimated maximum credible ground
acceleration was determined to be approximately 0.48g for the Rose Canyon Fault. Presented on the
following table are the earthquake events and site accelerations for faults considered most likely to
subject the site to ground shaking.
Project No. 06514-52-03 - 3 - October 16,2001
It is our opinion that the site could be subjected to moderate to severe ground shaking in the event of a
major earthquake along any of the faults mentioned in Table 5.1; however, the seismic risk at the site is
not considered significantly greater than the surrounding area.
TABLE 5.1
Fault Name
Rose Canyon
Newport Inglewood
Coronado Bank
Elsinore-Julian
Elsinore-Temecula
Distance
From
Site (miles)
3/2
7/2
19/2
26
26
Maximum
Credible
Event
6.9
6.9
7.4
7.1
6.8
Maximum
Credible Site
Acceleration (g)
0.48
0.32
0.17
0.10
0.08
5.2 Liquefaction
Dense, formational soils of the Terrace Deposits underlie the site to a depth of approximately 23 feet
followed by the Santiago Formation. Liquefaction occurs in loose cohesionless soils located beneath the
water table that are subjected to large accelerations during strong earthquakes. Due to the dense nature
of the formational units, it is our opinion that the potential for liquefaction of the site subsoils is low to
remote.
Project No. 06514-52-03 -4-October 16, 2001
6. CONCLUSIONS AND RECOMMENDATIONS
6.1 General
6.1.1 It is our opinion that no soil or geologic conditions were encountered during the course of the
investigation that would preclude the construction of the proposed structures provided the
recommendations of this report are followed.
6.1.2 Subsurface conditions indicated by the exploratory boring may be extrapolated to reflect
general soil/geologic conditions; however, some variations between locations should be
anticipated.
6.1.3 Grading to achieve design finish grades for the pump station and associated improvements is
anticipated to be relatively minor with cuts and fills on the order of one foot. The construction
of cut or fill slopes are not planned for the project.
6.1.4 The proposed pump station and associated improvements will be founded in dense formational
units. Conventional continuous and isolated spread footings are suitable for the proposed
structures.
6.1.5 A relatively shallow groundwater condition exists at the site. Dewatering will be required
during construction of the below-grade improvements. Other considerations may impact site
development including sloping the sides of excavations as discussed below.
6.2 Excavation Characteristics and Dewatering
6.2.1 It is understood that the deepest floor slab of the below-grade portion of the structure (wet
well) will be located on the order of 30 feet below the adjacent finish grade. Therefore, with
the presence of shallow groundwater, dewatering and the stability of slopes excavated at or
below the water level are important considerations during construction.
6.2.2 Based on our experience with the Terrace Deposits, we anticipate the soils to possess
relatively moderate to high permeability. Therefore, it is our opinion that a well point system
or a "cut off trench in which water may be pumped from may be suitable for dewatering
construction excavations. The dewatering system, by any method, is considered the
responsibility of the contractor including the design and implementation. Dewatering systems
should be implemented by the contractor to provide safe and workable conditions within the
temporary excavations. The contractor should consider any discharge permits and/or
requirements of governing agencies.
Project No. 06514-52-03 - 5 - October 16, 2001
6.2.3 It is our opinion that the soils on the site, in general, can be excavated with conventional
heavy-duty grading equipment. Saturated soils excavated from below the groundwater level
will require drying back to suitable moisture content prior to replacement as backfill or
mixing with dry soils, if available.
6.2.4 Temporary excavations should be sloped back during construction of the underground
facilities. These slopes should have an inclination no steeper than 1:1 (horizontal: vertical) in
order to provide an adequate factor of safety and the groundwater should be lowered below
the bottom of the excavation. It should be the contractor's responsibility to provide sufficient
and safe support for the excavation, as well as nearby utilities, structures and other
improvements that could be damaged by earth movements. The maximum inclination value
assumes that no surcharge loading will encroach within a horizontal distance from the top of
the excavation equal to the depth of excavation. If vertical temporary excavations are
required, the contractor should provide appropriate sheet piling or shoring systems such as
soldier piles with lagging. Temporary excavations should be in compliance with the
applicable governing agency regulations. Design and implementation piling or of shoring
systems are the responsibility of the contractor. The slopes should be monitored by a
contractor representative familiar with applicable governing agency safety regulations. At
any time, if soil sloughing or slope movement is noted, the excavation should be evacuated of
personnel and the soils consultant contacted for further evaluation.
6.2.5 If an open excavation is restricted (such as by the existing utilities or property boundaries)
other alternatives such as shoring/bracing or sheet-piling system may be utilized in lieu of the
temporary excavations and dewatering. The contractor is considered responsible for design
and implementation of any alternative system. However, the soils engineer should be
consulted for supplemental soil design parameters.
6.3 Corrosion
6.3.1 Laboratory tests were performed on soil anticipated to be encountered to determine the
percentage of water-soluble sulfate present. The test results indicate that concrete structures
exposed to soils at the locations tested have a "negligible" water-soluble sulfate exposure as
defined in the 1997 UBC Table 19-A-4. No special concrete design requirements are set forth
in the UBC due to concrete exposed to "negligible" amount of sulfate. The results to the
laboratory sulfate tests are presented in Appendix B, Table B-EL
8.3.2 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, if
improvements that could be susceptible to corrosion are planned, it is recommended that
further evaluation by a corrosion engineer be performed.
Project No. 06514-52-03 -6- October 16,2001
6.4 Grading
6.4.1 All anticipated grading for site development should be performed in accordance with the
Recommended Grading Specifications contained in Appendix C, and in accordance with
pertinent ordinances of the City of Carlsbad. Where recommendations of Appendix C conflict
with this section of the report, the recommendations of this section shall take precedence. All
earthwork, including fill and retaining and below grade wall and utility trench backfill,
should be observed by, and all compacted fill tested by, representatives of Geocon
Incorporated.
6.4.2 Site preparation should begin with the removal of all deleterious matter and vegetation in
areas to be improved. The depth of removal should be such that the material to be used as fill
is free of organic matter. Materials generated during stripping operations should be exported
from the site to an approved location. In addition, the topsoil materials will require remedial
grading to adjust moisture content and compact to specified relative compaction.
6.4.3 All backfilling operations should be performed to achieve subgrade elevations by compacting
structural fill in layers. In general, native soils are suitable for reuse as fill if free from
vegetation, debris and other deleterious matter. Layers of fill should be not thicker than will
allow for adequate bonding and compaction. In areas of proposed improvements, all fill
(including backfill and scarified ground surfaces) should be compacted to at least 90 percent
of maximum dry density at or slightly above optimum moisture content in accordance with
ASTM Test Procedure D1557-91.
6.4.4 Excavated soils that are saturated or overly wet of optimum will need to be dried back to a
suitable moisture content. This may be accomplished by grading and aerating or mixing with
drier materials, if available. Overly wet soils will be cause for rejection as suitable fill at the
discretion of the soils engineer.
6.4.5 If existing underground utility lines are to be abandoned, they should be removed and the
resulting excavation backfilled with properly compacted soil.
6.4.6 The design earth pressures provided herein for the below-grade pump station walls assume
no additional loading resulting from compacting of backfill soils placed against the walls. We
recommend that these soils be placed in shallow lifts and compacted with manually operated
equipment. Consideration may be given to backfilling the zone adjacent to the walls with a
clean granular material that would require less compaction effort.
Project No. 06514-52-03 - 7 - October 16, 2001
6.5 Seismic Design Criteria
The following table summarizes site-specific seismic design criteria obtained from the 1997
Uniform Building Code (UBC). The values listed in Table 6.5 are for the Rose Canyon Fault
(located approximately 4 miles west of the site) that is identified as a Type B fault and is
more dominant than the nearest Type A fault due to its close proximity to the site.
TABLE 6.5
SEISMIC DESIGN PARAMETERS
Parameter
Seismic Zone Factor, Z
Soil Profile Type
Seismic Coefficient, Ca
Seismic Coefficient, Cv
Near-Source Factor, Na
Near-Source Factor, Nv
Seismic Source
Value
0.40
SD
0.44
0.74
1.0
1.2
B
UBC Reference
Table 16-1
Table 16-J
Table 16-Q
Table 16-R
Table 16-S
Table 16-T
Table 16-U
6.6 Foundations-Generator and Transformer Buildings
6.6.1 The generator and transformer buildings can be supported on continuous strip footings and
slab-on-grade founded on formational soils as previously discussed.
6.6.2 It is recommended that continuous strip footings have a minimum width of 12 inches and
have a minimum depth of 12 inches as measured from the lowest adjacent finish grade. At
that depth and width, strip footings may be designed with an allowable soil bearing pressure
of 2,000 psf. This soil bearing pressure is for dead plus live loads and may be increased by
one-third when considering transient loads due to wind or seismic forces.
6.6.3 Steel reinforcement for the footings should be designed by the project structural engineer,
however, it is recommended that minimum reinforcement for continuous strip footings
consist of four No. 4 reinforcing bars, two placed within the top of the footing and two placed
near the bottom of the footing.
6.6.4 Concrete slabs for the structure should have a minimum thickness of 4 inches and be
underlain by at least 4 inches of clean sand. Reinforcement, as a minimum, should consist of
No. 3 reinforcing bars placed at 18 inches in both directions. Slab thickness and reinforcing
Project No. 06514-52-03 October 16, 2001
should be reviewed by the structural engineer and design modifications specified if heavy or
concentrated floor loading is anticipated.
6.6.5 All slabs expected to receive moisture sensitive floor covering or where moisture migration
through the slab is undesirable should be underlain by a vapor barrier covered with 2 inches
of the clean bedding sand recommended above.
6.6.6 All footing excavations should be observed by a representative of Geocon Incorporated prior
to placing steel reinforcement or concrete. If unanticipated soils are encountered in the
excavations, foundation modifications may be required.
6.7 Foundation-Pump Structure
6.7.1 It is our opinion that the main pump station structure can be supported on a reinforced
concrete mat foundation founded on formational material and/or properly compacted fill.
6.7.2 An allowable soil bearing pressure of 3,000 psf may used in design of the mat foundation. A
modulus of subgrade reaction, k, equal to 150 pci may also be assumed. Hydrostatic pressure
exerted upward should be accounted for in design of the mat. An upward pressure of
1,650 psf may be used in design.
6.7.3 The concrete mat should be underlain by 6 inches of crushed rock. The thickness and
reinforcing of the concrete mat should be designed by the structural engineer considering
vertical loading as well as the hydrostatic (buoyant) pressures due to the presence of the
shallow groundwater at an elevation above the floor level.
6.7.4 The excavation for the pump station structure should be observed by a representative of
Geocon Incorporated prior to placing the gravel bedding, steel, or concrete. If anticipated
soils are encountered in the excavation, foundation modifications may be required.
6.8 Lateral Earth Pressures-Retaining Walls
6.8.1 Retaining walls (at grade) not restrained at the top and having a level backfill surface should
be designed for an active soil pressure equivalent to the pressure exerted by a fluid density of
30 pounds per cubic foot (pcf). Where the backfill will be inclined at no steeper than 2:1, an
active soil pressure of 40 pcf is recommended. These soil pressures assume no surcharge at
that the backfill materials within an area bounded by the wall and a 1:1 plane extending
upward from the base of the wall possess an Expansion Index of less than 50.
Project No. 06514-52-03 - 9 - October 16, 2001
6.8.2 Unrestrained walls are those that are allowed to rotate more than 0.001 H at the top of the
wall. Where walls are restrained from movement at the top, an additional uniform pressure of
7H psf (where H equals the height of the retaining wall portion of the wall in feet) should be
added to the above active soil pressure.
6.8.3 The above pressure assumes that the retaining walls will be provided with a drainage system
adequate to prevent the buildup of hydrostatic forces and are waterproofed as required by the
project civil engineer or architect. The use of drainage openings through the base of the wall
(weep holes, etc.) is not recommended where seepage could be a nuisance or otherwise
impact the property adjacent to the wall. A drainage system behind the wall is recommended
consisting of perforated pipe and the gravel encased in geotextile fabric (Mirafi 140N or
equivalent).
6.8.4 In general, retaining wall foundations having a minimum depth and width of one foot may be
designed for an allowable soil bearing pressure of 2,000 psf, provided the soil within 3 feet
below the base of the wall has an Expansion Index of less than 90. The proximity of the
foundation to the top of a slope steeper that 3:1 could impact the allowable soil bearing
pressure. Therefore, Geocon Incorporated should be consulted where such a condition is
anticipated.
6.9 Lateral Earth Pressures-Main Structure
6.9.1 The below grade walls of the pump station structure should be designed to withstand earth
and hydrostatic pressures. It is assumed that the walls will be laterally supported by floor
beams, therefore, they have been analyzed as nonyielding walls. It is recommended that these
walls be designed to withstand a lateral pressure exerted by an equivalent fluid weight of 80
pcf, plus an additional uniform pressure of 7H psf (where H equals the below grade height of
the wall).
6.9.2 Design of the wall should also account for any loading due to the presence of adjacent
structures, if present, hi these areas, an additional uniform pressure should be applied in the
design equal to 0.5q where q is the equivalent uniform surcharge loading of the adjacent
structure in pounds per square foot (psf). Where a traffic surcharge occurs within a horizontal
distance less than two-thirds the height of the wet well/pump room wall, an additional
uniform horizontal pressure of 70 psf should be applied to the above lateral pressures.
6.9.3 Waterproofing and/or concrete design to mitigate migration of water through the walls should
be specified by the design engineer.
Project No. 06514-52-03 - 10 - October 16, 2001
6.10 Lateral Load Resistance
6.10.1 Lateral loads may be resisted by passive earth pressure and friction. Allowable passive earth
pressures against shallow spread or continuous strip footings poured neat against properly
compacted fill soils or to undisturbed formational soils should be considered as being equal
to the forces exerted by a fluid unit weight of 300 pcf. A coefficient of friction of 0.40 may
be used between the base of footings and slabs and the soil for computing resistance to
sliding. The friction coefficient may be combined with the allowable passive earth pressure
when determining total resistance to lateral loads.
6.11 Site Drainage
6.11.1 Adequate drainage provisions are imperative. Under no circumstances should water be
allowed to pond adjacent to footings. The site should be graded and maintained such that
surface drainage is directed away from structures and the top of the slopes into swales or
other controlled drainage devices. All roof and pavement drainage should be directed into
splash block or into conduits which carry runoff away from the proposed structure.
6.12 Foundation and Grading Plan Review
6.12.1 Geocon Incorporated should review the grading plans, as well as any retaining wall plans,
and foundation plans prior to final design submittal to determine if additional analysis/
recommendations are required.
Project No. 06514-52-03 -11 - October 16, 2001
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. The recommendations of this report pertain only to the site investigated and are based upon
the assumption that the soil conditions do not deviate from those disclosed in the
investigation. If any variations or undesirable conditions are encountered during construction,
or if the proposed construction will differ from that anticipated herein, Geocon Incorporated
should be notified so that supplemental recommendations can be given. The evaluation or
identification of the potential presence of hazardous or corrosive materials was not part of the
scope of services provided by Geocon Incorporated.
2. This report is issued with the understanding that it is the responsibility of the owner, or of his
representative, to ensure that the information and recommendations contained herein are
brought to the attention of the architect and engineer for the project and incorporated into the
plans, and the necessary steps are taken to see that the contractor and subcontractors carry out
such recommendations in the field.
3. The findings of this report are valid as of the present date. However, changes in the
conditions of a property can occur with the passage of time, whether they be due to natural
processes or the works of man on this or adjacent properties. In addition, changes in
applicable or appropriate standards may occur, whether they result from legislation or the
broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly
or partially by changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
Project No. 06514-52-03 October 16, 2001
V
SOURCE: 2001 THOMAS BROTHERS MAP
SAN DIEGO COUNTY, CALIFORNIA
REPRODUCED WITH PERMISSION GRANTED BY THOMAS BROTHERS MAPS.
THIS MAP IS COPYRIGHTED BY THOMAS BROS. MAPS. IT IS UNLAWFUL TO COPY
OR REPRODUCE ALL OR ANY PART THEREOF, WHCTHER FOR PERSONAL USE OR
RESALE, WITHOUT PERMISSION
N
NO SCALE
GBOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
VICINITY MAP
POINSETTIA PROPERTIES
SEWER PUMP STATION
CARLSBAD, CALIFORNIA
KA/RSS DSK/DOOOD DATE 10-16-2001 PROJECT NO. 06514 - 52 - 03 FIG. 1
1GVICMAP
WET WELL/
DRY PITSTRUCTURE
LOT 225
TRANSFORMER-
LOT 224
NO SCALE
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
SITE PLAN
POINSETTIA PROPERTIES
SEWER PUMP STATION
CARLSBAD, CALIFORNIA
KA/RSS DSK/DOOOD DATE 10-16-2001 PROJECT NO. 06514 - 52 - 3 FIG. 2
6514KA/RSS
«i
LEGEND
" ® APPROX. LOCATION OF BORING
Oaf FILL
Qal/Qt ALLUVIUM OVER TERRACE DEPOSIT
Qt TERRACE DEPOSIT
"*-•— — • APPROX. GEOLOGIC CONTACT
M
SCALE :1"« 80'
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
GEOLOGIC MAP
POINSETTIA PROPERTIES
SEWER PUMP STATION
CARLSBAD, CALIFORNIA
KPA/RSS DSK/EOOOO DATE 10-16-2001 PROJECT NO. 06514-52-03 FIG. 3
6514KA1/RSS
APPENDIX
APPENDIX A
FIELD INVESTIGATION
The field investigation was performed on September 26, 2001, and consisted of a site reconnaissance
and the excavation of one exploratory boring. The approximate location of the boring is shown on
Figure 3, Geologic Map.
The exploratory boring was advanced to a depth of 46 feet below existing grade utilizing a truck-
mounted Ingersoll-Rand, A-300 drill rig equipped with an 8-inch-diameter hollow-stem auger.
Relatively undisturbed samples were obtained from the borings by driving a three-inch O.D. tube
sampler 12 inches into the undisturbed soil mass with a 140-pound hammer falling 30 inches. Standard
Penetration Tests (SPT) were also performed at various depths in the borings. Bulk samples were also
collected. The soils encountered in the excavation were visually examined and logged. The log of
boring is presented in Figures A-l and A-2.
Project No. 06514-52-03 October 16, 2001
PROJECT NO. 06514-52-03
DEPTH
IN
FEET
rvU
- 2 -
A~ 4
- 6 -
- 8 -
- 10 -
- 12 -
-
- 14 -
- 16 -
- 18 -
-
- 20 -
-
- 22 -
- 24 -
—
- 26 -
- 28 -
SAMPLE
NO.
1
1
Bl-1 I
§Bl-2 I
1L
Bl-3 1
Bl-4 I
P
Bl-5
Bl-6
Bl-7
iso
oI
H
~"
1 ' "•'•[{•'
j-H .
-•h'-'j j- '
l:-.-"-:-vfe;vK:A1i
v.-V.'-fS
>•'/!'.'£
>.-v!>j:-:
•1- !-"'•-J.-I-
~'l\'-'It .: <-.iJ -
',- */. •''•'.•
-• V "- '"'•'
v.-v!".^.-
o:in
<n
Q
o
U)
I
SOIL
CLASS
(USCS)
SM
SC
SM
SC
T* y"V"¥"* TTk.T^~^ T* •<BORING B 1
ELEV. (MSL.) 49 DATE COMPLETED 9/26/01
EQUIPMENT IR A-300
MATERIAL DESCRIPTION
ALLUVIUM
Loose, dry to damp, light reddish-brown, Silty, fine
to medium SAND with little clay
-Becomes medium dense, damp to moist
TERRACE DEPOSITS
Medium dense, damp, light yellow tan, fine to
medium SAND with some clay
-Becomes dense
Dense, saturated, light yellow-tan, Silty, fine to
medium SAND
-Becomes coarse-grained
-Becomes light gray with some yellow fine-grained
sand
SANTIAGO FORMATION
Dense, wet, light gray-white, fine to medium SAND
with some clay
ZQJ^
U. 2|
^E tT \
Q- tfi U)
uiHo
Lu^mQ_ut-N^
21
14
71
41
43
44
>-
m *
gjj
Q •
ce^a
113.7
107.2
123.0
104.2
^fV^
frz
HHEo0
7.7
5.9
10.1
24.3
Figure A-l, Log of Boring B 1 PPR
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL C . . . STANDARD PENETRATION TEST •... DRIVE SAMPLE (UNDISTURBED)
... DISTURBED OR BAG SAMPLE ... CHUNK SAMPLE f. . . . WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06514-52-03
DEPTH
IN
FEET
30
_
- 32 -
- 34 -
- 36 -
- 38 -
- 40 -
- 42 -
- 44 -
- 46 -
SAMPLE
NO.
Bl-8 1
f
Bl-9
Bl-10
Bl-11
CDO
O
|—
H
\
•'.'•'.'
- " . -
.-'_-"
s /
(Ytu
<t
a
— io(VCO
SOIL
CLASS
(USCS)
SP-CL
ML
BORING B 1
ELEV. (MSL.) 49 DATE COMPLETED 9/26/01
EQUIPMENT IR A-300
MATERIAL DESCRIPTION
Becomes very dense, moist to very moist, light
grayish-white, fine to medium SAND with some
interbeds of clay and some coarse sand
-Becomes white with trace of silt and trace of clay
Becomes hard, moist, light gray, Clayey SILT
BORING TERMINATED AT 46.5 FEET
Groundwater encountered at 13 feet
ow~°y^«1^
£«T
Ul^CD
0.°^*-'
91
-
57
-
86
-
74
>
H~
^ •
o:w
a
119.2
~
Qi^
M[~Q!Z£
a
16.0
Figure A-2, Log of Boring B 1 PPR
SAMPLE SYMBOLS O... SAMPLING UNSUCCESSFUL C... STANDARD PENETRATION TEST •... DRIVE SAMPLE (UNDISTURBED)
S3 ... DISTURBED OR BAG SAMPLE B ... CHUNK SAMPLE f. ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
APPENDIX
APPENDIX B
LABORATORY TESTING
Laboratory tests were performed in accordance with generally accepted test methods of the American
Society for Testing and Materials (ASTM) or other suggested procedures. Selected samples were
tested for their in-place density and moisture content, direct shear strength, and water-soluble sulfate
content. The results of these tests are summarized on the boring log, Figures A-l and A-2, and
Tables B-I and B-H.
TABLE B-I
SUMMARY OF LABORATORY DIRECT SHEAR TEST RESULTS
ASTM D 3080-98
Sample No.
Bl-6
Bl-8
Dry Density
(pcf)
104.2
119.2
Moisture Content
(%)
24.3
16.0
Unit Cohesion
(psf)
860
130
Angle of Shear
Resistance (degrees)
30
46
TABLE B-ll
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No.
Bl-3
Bl-8
Water Soluble Sulfate (%)
0.007
0.003
Sulfate Expose
Negligible
Negligible
Project No. 06514-52-03 October 16, 2001
APPENDIX
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
for
POINSETTIA PROPERTIES SEWER PUMP STATION
CARLSBAD, CALIFORNIA
PROJECT NO. 06514-52-03
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
1.1. These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon Incorporated. The recom-
mendations contained in the text of the Geotechnical Report are a part of the earthwork and
grading specifications and shall supersede the provisions contained hereinafter in the case
of conflict.
1.2. Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be
employed for the' purpose of observing earthwork procedures and testing the fills for
substantial conformance with the recommendations of the Geotechnical Report and these
specifications. It will be necessary that the Consultant provide adequate testing and
observation services so that he may determine that, in his opinion, the work was performed
in substantial conformance with these specifications. It shall be the responsibility of the
Contractor to assist the Consultant and keep him apprised of work schedules and changes
so that personnel may be scheduled accordingly.
1.3. It shall be the sole responsibility of the Contractor to provide adequate equipment and
methods to accomplish the work in accordance with applicable grading codes or agency
ordinances, these specifications and the approved grading plans. If, in the opinion of the
Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture
condition, inadequate compaction, adverse weather, and so forth, result in a quality of work
not in conformance with these specifications, the Consultant will be empowered to reject
the work and recommend to the Owner that construction be stopped until the unacceptable
conditions are corrected.
2. DEFINITIONS
2.1. Owner shall refer to the owner of the property or the entity on whose behalf the grading
work is being performed and who has contracted with the Contractor to have grading
performed.
2.2. Contractor shall refer to the Contractor performing the site grading work.
2.3. Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer
or consulting firm responsible for preparation of the grading plans, surveying and verifying
as-graded topography.
GI rev. 8/98
2.4. Consultant shall refer to the soil engineering and engineering geology consulting firm
retained to provide geotechnical services for the project.
2.5. Soil Engineer shall refer to a California licensed Civil Engineer retained by the Owner,
who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be
responsible for having qualified representatives on-site to observe and test the Contractor's
work for conformance with these specifications.
2.6. Engineering Geologist shall refer to a California licensed Engineering Geologist retained
by the Owner to provide geologic observations and recommendations during the site
grading.
2.7. Geotechnical Report shall refer to a soil report (including all addenda) which may include
a geologic reconnaissance or geologic investigation that was prepared specifically for the
development of the project for which these Recommended Grading Specifications are
intended to apply.
3. MATERIALS
3.1. Materials for compacted fill shall consist of any soil excavated from the cut areas or
imported to the site that, in the opinion of the Consultant, is suitable for use in construction
of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as
defined below.
3.1.1. Soil fills are defined as fills containing no rocks or hard lumps greater than 12
inches in maximum dimension and containing at least 40 percent by weight of
material smaller than 3/4 inch in size.
3.1.2. Soil-rock fills are defined as fills containing no rocks or hard lumps larger than 4
feet in maximum dimension and containing a sufficient matrix of soil fill to allow
for proper compaction of soil fill around the rock fragments or hard lumps as
specified in Paragraph 6.2. Oversize rock is defined as material greater than 12
inches.
3.1.3. Rock fills are defined as fills containing no rocks or hard lumps larger than 3 feet
in maximum dimension and containing little or no fines. Fines are defined as
material smaller than 3/4 inch in maximum dimension. The quantity of fines shall
be less than approximately 20 percent of the rock fill quantity.
GI rev. 8/98
3.2. Material of a perishable, spongy, or otherwise unsuitable nature as determined by the
Consultant shall not be used in fills.
3.3. Materials used for fill, either imported or on-site, shall not contain hazardous materials as
defined by the California Code of Regulations, Title 22, Division 4, Chapter 30, Articles 9
and 10; 40CFR; and any other applicable local, state or federal laws. The Consultant shall
not be responsible for the identification or analysis of the potential presence of hazardous
materials. However, if observations, odors or soil discoloration cause Consultant to
suspect the presence of hazardous materials, the Consultant may request from the Owner
the termination of grading operations within the affected area. Prior to resuming grading
operations, the Owner shall provide a written report to the Consultant indicating that the
suspected materials are not hazardous as defined by applicable laws and regulations.
3.4. The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of
properly compacted soil fill materials approved by the Consultant. Rock fill may extend to
the slope face, provided that the slope is not steeper than 2:1 (horizontal:vertical) and a soil
layer no thicker than 12 inches is track-walked onto the face for landscaping purposes.
This procedure may be utilized, provided it is acceptable to the governing agency, Owner
and Consultant.
3.5. Representative samples of soil materials to be used for fill shall be tested in the laboratory
by the Consultant to determine the maximum density, optimum moisture content, and,
where appropriate, shear strength, expansion, and gradation characteristics of the soil.
3.6. During grading, soil or ground water conditions other than those identified in the
Geotechnical Report may be encountered by the Contractor. The Consultant shall be
notified immediately to evaluate the significance of the unanticipated condition
4. CLEARING AND PREPARING AREAS TO BE FILLED
4.1. Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of
complete removal above the ground surface of trees, stumps, brush, vegetation, man-made
structures and similar debris. Grubbing shall consist of removal of stumps, roots, buried
logs and other unsuitable material and shall be performed in areas to be graded. Roots and
other projections exceeding 1-1/2 inches in diameter shall be removed to a depth of 3 feet
below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to
provide suitable fill materials.
GI rev. 8/98
4.2. Any asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility. Concrete fragments which are free of reinforcing
steel may be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3
of this document.
4.3. After clearing and grubbing of organic matter or other unsuitable material, loose or porous
soils shall be removed to the depth recommended in the Geotechnical Report. The depth of
removal and compaction shall be observed and approved by a representative of the
Consultant. The exposed surface shall then be plowed or scarified to a minimum depth of
6 inches and until the surface is free from uneven features that would tend to prevent
uniform compaction by the equipment to be used.
4.4. Where the slope ratio of the original ground is steeper than 6:1 (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Finish Grade Original Ground
Finish Slope Surface
Remove All
Unsuitable Material
As Recommended By
Soil Engineer Slope To Be Such That
Sloughing Or Sliding
Does Not Occur Varies
"B"
See Note 1 See Note 2 -
No Scale
DETAIL NOTES:(1) Key width "B" should be a minimum of 10 feet wide, or sufficiently wide to
permit complete coverage with the compaction equipment used. The base of the
key should be graded horizontal, or inclined slightly into the natural slope.
(2) The outside of the bottom key should be below the topsoil or unsuitable surficial
material and at least 2 feet into dense formational material. Where hard rock is
exposed in the bottom of the key, the depth and configuration of the key may be
modified as approved by the Consultant.
GI rev. 8/98
4.5. After areas to receive fill have been cleared, plowed or scarified, the surface should be
disced or bladed by the Contractor until it is uniform and free from large clods. The area
should then be moisture conditioned to achieve the proper moisture content, and compacted
as recommended in Section 6.0 of these specifications.
5. COMPACTION EQUIPMENT
5.1. Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel
wheeled rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of
acceptable compaction equipment. Equipment shall be of such a design that it will be
capable of compacting the soil or soil-rock fill to the specified relative compaction at the
specified moisture content.
5.2. Compaction of rock fills shall be performed in accordance with Section 6.3.
6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL
6.1. Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with
the following recommendations:
6.1.1. Soil fill shall be placed by the Contractor in layers that, when compacted, should
generally not exceed 8 inches. Each layer shall be spread evenly and shall be
thoroughly mixed during spreading to obtain uniformity of material and moisture
in each layer. The entire fill shall be constructed as a unit in nearly level lifts.
Rock materials greater than 12 inches in maximum dimension shall be placed in
accordance with Section 6.2 or 6.3 of these specifications.
6.1.2. In general, the soil fill shall be compacted at a moisture content at or above the
optimum moisture content as determined by ASTM D1557-91,
6.1.3. When the moisture content of soil fill is below that specified by the Consultant,
water shall be added by the Contractor until the moisture content is in the range
specified.
6.1.4. When the moisture content of the soil fill is above the range specified by the
Consultant or too wet to achieve proper compaction, the soil fill shall be aerated by
the Contractor by blading/mixing, or other satisfactory methods until the moisture
content is within the range specified.
GI rev. 8/98
6.1.5. After each layer has been placed, mixed, and spread evenly, it shall be thoroughly
compacted by the Contractor to a relative compaction of at least 90 percent.
Relative compaction is defined as the ratio (expressed in percent) of the in-place
dry density of the compacted fill to the maximum laboratory dry density as
determined in accordance with ASTM D1557-91. Compaction shall be continuous
over the entire area, and compaction equipment shall make sufficient passes so that
the specified minimum relative compaction has been achieved throughout the
entire fill.
6.1.6. Soils having an Expansion Index of greater than 50 may be used in fills if placed at
least 3 feet below finish pad grade and should be compacted at a moisture content
generally 2 to 4 percent greater than the optimum moisture content for the material.
6.1.7. Properly compacted soil fill shall extend to the design surface of fill slopes. To
achieve proper compaction, it is recommended that fill slopes be over-built by at
least 3 feet and then cut to the design grade. This procedure is considered
preferable to track-walking of slopes, as described in the following paragraph.
6.1.8. As an alternative to over-building of slopes, slope faces may be back-rolled with a
heavy-duty loaded sheepsfoot or vibratory roller at maximum 4-foot fill height
intervals. Upon completion, slopes should then be track-walked with a D-8 dozer
or similar equipment, such that a dozer track covers all slope surfaces at least
twice.
6.2. Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance
with the following recommendations:
6.2.1. Rocks larger than 12 inches but less than 4 feet in maximum dimension may be
incorporated into the compacted soil fill, but shall be limited to the area measured
15 feet minimum horizontally from the slope face and 5 feet below finish grade or
3 feet below the deepest utility, whichever is deeper.
i
6.2.2. Rocks or rock fragments up to 4 feet in maximum dimension may either be
individually placed or placed in windrows. Under certain conditions, rocks or rock
fragments up to 10 feet in maximum dimension may be placed using similar
methods. The acceptability of placing rock materials greater than 4 feet in
maximum dimension shall be evaluated during grading as specific cases arise and
shall be approved by the Consultant prior to placement.
GI rev. 8/98
6.2.3. For individual placement, sufficient space shall be provided between rocks to allow
for passage of compaction equipment.
6.2.4. For windrow placement, the rocks should be placed in trenches excavated in'
properly compacted soil fill. Trenches should be approximately 5 feet wide and 4
feet deep in maximum dimension. The voids around and beneath rocks should be
filled with approved granular soil having a Sand Equivalent of 30 or greater and
should be compacted by flooding. Windrows may also be placed utilizing an
"open-face" method in lieu of the trench procedure, however, this method should
first be approved by the Consultant.
6.2.5. Windrows should generally be parallel to each other and may be placed either
parallel to or perpendicular to the face of the slope depending on the site
geometry. The minimum horizontal spacing for windrows shall be 12 feet
center-to-center with a 5 -foot stagger or offset from lower courses to next
overlying course. The minimum vertical spacing between windrow courses shall
be 2 feet from the top of a lower windrow to the bottom of the next higher
windrow.
6.2.6. All rock placement, fill placement and flooding of approved granular soil in the
windrows must be continuously observed by the Consultant or his representative.
6.3. Rock fills, as defined in Section 3.1.3., shall be placed by the Contractor in accordance with
the following recommendations:
6.3.1. The base of the rock fill shall be placed on a sloping surface (minimum slope of 2
percent, maximum slope of 5 percent). The surface shall slope toward suitable
subdrainage outlet facilities. The rock fills shall be provided with subdrains during
construction so that a hydrostatic pressure buildup does not develop. The
subdrains shall be permanently connected to controlled drainage facilities to
control post-construction infiltration of water.
6.3.2. Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock
trucks traversing previously placed lifts and dumping at the edge of the currently
placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the
rock. The rock fill shall be watered heavily during placement. Watering shall
consist of water trucks traversing in front of the current rock lift face and spraying
water continuously during rock placement. Compaction equipment with
compactive energy comparable to or greater than that of a 20-ton steel vibratory
roller or other compaction equipment providing suitable energy to achieve the
^ 8/gg
required compaction or deflection as recommended in Paragraph 6.3.3 shall be
utilized. The number of passes to be made will be determined as described in
Paragraph 6.3.3. Once a rock fill lift has been covered with soil fill, no additional
rock fill lifts will be permitted over the soil fill.
6.3.3. Plate bearing tests, in accordance with ASTM Dl 196-64, may be performed in
both the compacted soil fill and in the rock fill to aid in determining the number of
passes of the compaction equipment to be performed. If performed, a minimum of
three plate bearing tests shall be performed in the properly compacted soil fill
(minimum relative compaction of 90 percent). Plate bearing tests shall then be
performed on areas of rock fill having two passes, four passes and six passes of the
compaction equipment, respectively. The number of passes required for the rock .
fill shall be determined by comparing the results of the plate bearing tests for the
soil fill and the rock fill and by evaluating the deflection variation with number of
passes. The required number of passes of the compaction equipment will be
performed as necessary until the plate bearing deflections are equal to or less than
that determined for the properly compacted soil fill. In no case will the required
number of passes be less than two.
6.3.4. A representative of the Consultant shall be present during rock fill operations to
verify that the minimum number of "passes" have been obtained, that water is
being properly applied and that specified procedures are being followed. The
actual number of plate bearing tests will be determined by the Consultant during
grading. In general,-at least one test should be performed for each approximately
5,000 to 10,000 cubic yards of rock fill placed.
6.3.5. Test pits shall be excavated by the Contractor so that the Consultant can state that,
in his opinion, sufficient water is present and that voids between large rocks are
properly filled with smaller rock material. In-place density testing will not be
required in the rock fills.
6.3.6. To reduce the potential for "piping" of fines into the rock fill from overlying soil
fill material, a 2-foot layer of graded filter material shall be placed above the
uppermost lift of rock fill. The need to place graded filter material below the rock
should be determined by the Consultant prior to commencing grading. The
gradation of the graded filter material will be determined at the time the rock fill is
being excavated. Materials typical of the rock fill should be submitted to the
Consultant in a timely manner, to allow design of the graded filter prior to the
commencement of rock fill placement.
GI rev. 8/98
6.3.7. All rock fill placement shall be continuously observed during placement by
representatives of the Consultant.
7. OBSERVATION AND TESTING
7.1. The Consultant shall be the Owners representative to observe and perform tests during
clearing, grubbing, filling and compaction operations. In general, no more than 2 feet in
vertical elevation of soil or soil-rock fill shall be placed without at least one field density
test being performed within that interval. In addition, a minimum of one field density test
shall be performed for every 2,000 cubic yards of soil or soil-rock fill placed and
compacted.
7.2. The Consultant shall perform random field density tests of the compacted soil or soil-rock
fill to provide a basis for expressing an opinion as to whether the fill material is compacted
as specified. Density tests shall be performed in the compacted materials below any
disturbed surface. When these tests indicate that the density of any layer of fill or portion
thereof is below that specified, the particular layer or areas represented by the test shall be
reworked until the specified density has been achieved.
7.3. During placement of rock fill, the Consultant shall verify that the minimum number of
passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant shall
request the excavation of observation pits and may perform plate bearing tests on the
placed rock fills. The observation pits will be excavated to provide a basis for expressing
an opinion as to whether the rock fill is properly seated and sufficient moisture has been
applied to the material. If performed, plate bearing tests will be performed randomly on
the surface of the most-recently placed lift. Plate bearing tests will be performed to provide
a basis for expressing an opinion as to whether the rock fill is adequately seated. The
maximum deflection in the rock fill determined in Section 6.3.3 shall be less than the
maximum deflection of the properly compacted soil fill. When any of the above criteria
indicate that a layer of rock fill or any portion thereof is below that specified, the affected
layer or area shall be reworked until the rock fill has been adequately seated and sufficient
moisture applied.
7.4. A settlement monitoring program designed by the Consultant may be conducted in areas of
rock fill placement. The specific design of the monitoring program shall be as
recommended in the Conclusions and Recommendations section of the project
Geotechnical Report or in the final report of testing and observation services performed
during grading.
GI rev. 8/98
7.5. The Consultant shall observe the placement of subdrains, to verify that the drainage devices
have been placed and constructed in substantial conformance with project specifications.
7.6. Testing procedures shall conform to the following Standards as appropriate:
7.6.1. Soil and Soil-Rock Fills:
7.6.1.1. Field Density Test, ASTM D1556-82, Density of Soil In-Place By the
Sand-Cone Method.
7.6.1.2. Field Density Test, Nuclear Method, ASTM D2922-81, Density of Soil and
Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
7.6.1.3. Laboratory Compaction Test, ASTM D1557-91, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound Hammer
and 18-Inch Drop.
7.6.1.4. Expansion Index Test, Uniform Building Code Standard 29-2, Expansion
Index Test.
7.6.2. Rock Fills
7.6.2.1. Field Plate Bearing Test, ASTM Dl 196-64 (Reapproved 1977) Standard
Method for Nonrepresentative Static Plate Load Tests of Soils and Flexible
Pavement Components, For Use in Evaluation and Design of Airport and
Highway Pavements.
8. PROTECTION OF WORK
8.1. During construction, the Contractor shall properly grade all excavated surfaces to provide
positive drainage and prevent ponding of water. Drainage of surface water shall be
controlled to avoid damage to adjoining properties or to finished work on the site. The
Contractor shall take remedial measures to prevent erosion of freshly graded areas until
such time as permanent drainage and erosion control features have been installed. Areas
subjected to erosion or sedimentation shall be properly prepared in accordance with the
Specifications prior to placing additional fill or structures.
8.2. After completion of grading as observed and tested by the Consultant, no further
excavation or filling shall be conducted except in conjunction with the services of the
Consultant.
GI rev. 8/98
9. CERTIFICATIONS AND FINAL REPORTS
9.1. Upon completion of the work, Contractor shall furnish Owner a certification by the Civil
Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of
elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot
horizontally of the positions shown on the grading plans. After installation of a section of
subdrain, the project Civil Engineer should survey its location and prepare an as-built plan
of the subdrain location. The project Civil Engineer should verify the proper outlet for the
subdrains and the Contractor should ensure that the drain system is free of obstructions.
9.2. The Owner is responsible for furnishing a final as-graded soil and geologic report
satisfactory to the appropriate governing or accepting agencies. The as-graded report
should be prepared and signed by a California licensed Civil Engineer experienced in
geotechnical engineering and by a California Certified Engineering Geologist, indicating
that the geotechnical aspects of the grading were performed in substantial conformance
with the Specifications or approved changes to the Specifications.
GI rev. 8/98