HomeMy WebLinkAbout06244-12-01; Rancho Carlsbad Detention Basin; Rancho Carlsbad Detention Basin; 2000-07-06I
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GEOTECHNICAL INVESTIGATION
RANCHO CARLSBAD
DETENTION BASIN
CARLSBAD, CALIFORNIA
PREPARED FOR
RICK ENGINEERING COMPANY
SAN DIEGO, CALIFORNIA
JULY 2000
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
Project No. 06244-12-01
July 6, 2000
Rick Engineering Company
5620 Friars Road
San Diego, California 92110
Attention:
Subject:
Mr. Wayne Chang
RANCHO CARLSBAD
DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOTECHNICAL INVESTIGATION
Gentlemen:
In accordance with our Proposal Number LG-98272 and your authorization, we have performed a
geotechnical investigation of the proposed detention basin embankment and its associated culvert.
This study also included a limited subsurface investigation at the confluence of Calaveras and Agua
Hedionda Creeks to characterize the soils at that location for future channel improvements.
The proposed embankment is located within the flood plain of Calaveras Creek, northeast of the
intersection of El Camino Real and Calaveras Drive in Carlsbad, California. The accompanying
report presents the results of the study and conclusions and recommendations pertaining to the
geotechnical aspects of constructing the proposed detention basin embankment and its associated
culverts. It is our opinion that the detention basin embankment may be constructed as proposed
provided that the recommendations contained herein are followed.
If you have any questions regarding this report, or if we may be of further service, please contact the
undersigned at your convenience.
Very truly yours,
GEOCON INCORPORA'
ICE 22527
AS:DFL:lek
(4) Addressee
(I/del) Recon
Attention: Mr. Gerald A. Scheid
iSadr
CEG 1778
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 DESCRIPTIONS 1
3. SOIL AND GEOLOGIC CONDITIONS 2
3.1 Alluvium (Qal) 2
3.2 Santiago Formation (Ts) 3
4. GROUNDWATER 3
5. GEOLOGIC HAZARDS 3
5.1 Faulting and Seismicity 3
5.2 Soil Liquefaction Potential 4
6. SETTLEMENT CONDITIONS 5
7. EMBANKMENT STABILITY 5
8. CONSTRUCTION PROCEDURES 7
8.1 Remedial Grading 7
8.2 Culvert Construction 7
9. CONCLUSIONS AND RECOMMENDATIONS 8
9.1 General 8
9.2 Channel Improvements 8
9.3 Grading 9
9.4 Slope Stability 10
9.5 Slope Maintenance 10
9.6 Grading Plan Review 11
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map
Figure 3, Cross Section A-A'
Figure 4, Cross Section B-B'
Figure 5, Magnitude Settlement Curve
Figure 6, Surficial Slope Stability Analysis
APPENDLX A
FIELD INVESTIGATION
Figures A-l-A-10, Logs of Borings
TABLE OF CONTENTS (Continued)
APPENDIX B
LABORATORY TESTING
Table B-I, Summary of Direct Shear Test Results
Table B-n, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Test Results
Figures B-l-B-2, Gradation Curves
Figures B-3-B-8, Consolidation Curves
Figures B-9-B-15, Time Rate Curves
APPENDIX C
SLOPE STABILITY ANALYSIS
Figures C-l-C-5
APPENDIX D
RECOMMENDED GRADING SPECIFICATIONS
GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the findings of a geotechnical investigation for the construction of the proposed
detention basin embankment and associated culverts in Carlsbad, California (see Figure 1, Vicinity
Map). The purpose of the investigation was to evaluate surficial and subsurface soil and geologic
conditions and provide conclusions and recommendations regarding the stability of the proposed
embankment and culverts. In addition, the soils in the vicinity of the confluence of Agua Hedionda
and Calaveras Creeks were evaluated regarding potential erosion characteristics for consideration in
future channel improvements.
The scope of the investigation consisted of a site reconnaissance and the excavation of 6 small-
diameter exploratory borings. With the exception of Boring B-l, the approximate locations of the
borings are indicated on the enclosed Geologic Map (Figure 2). Boring B-l was excavated
approximately 50 feet west of the confluence of Agua Hedionda and Calaveras Creeks and is not
shown on Figure 2.
Laboratory tests were performed on selected soil samples obtained from the small-diameter borings
to evaluate pertinent geotechnical characteristics. Details of the field investigation and the laboratory
testing are presented in Appendices A and B, respectively.
In addition to the field investigation and laboratory testing, a review of pertinent reports and maps on
file and/or previously prepared by Geocon Incorporated was conducted, including: Generalized
Geologic Map, Calavera Hills Phase II, EIR Exhibit, prepared by Geosoils, dated October, 1999.
The recommendations contained herein are based on an analysis of the data obtained from the field
investigation, laboratory testing, the referenced documents and experience with similar soil and
geologic conditions.
2. SITE AND PROJECT DESCRIPTIONS
The subject site consists of partially developed and agricultural land located within the Rancho
Carlsbad area in Carlsbad, California (see Figure 1, Vicinity Map). The area is marked by a canyon
trending north to south through the site. To the south is a mobile home park. The proposed
improvements are part of the mitigation required to prevent flooding of the adjacent mobile home
park.
Project No. 06244-12-01 - 1 - July 6, 2000
Grading is planned at the confluence of Agua Hedionda Creek and Calaveras Creek to establish a
proper hydraulic channel profile. Grading plans were not available at the time of our study.
A soil berm detention basin is planned for Calaveras Creek, just north of the existing mobile home
park. The soil berms are planned to have a height of approximately 12 feet and side slopes of 2:1
(horizontal:vertical). In addition, the northwest to southeast trending berm will be extended to the
southeast to cross and dam the existing creek bed. A 9-foot-diameter corrugated arch and a 6-foot-
diameter reinforced concrete pipe are planned to convey storm water runoff from the detention basin
and the dammed creek bed southward to the main Calaveras Creek channel.
It is our understanding that a live water line and sewer line exist just east of Calaveras Creek which
may be impacted by the construction of the embankment fills. It is further understood that the
detention basin embankments may be ultimately replaced by embankments constructed for the
proposed extensions of College Boulevard and Cannon Road. These much higher embankments (up
to 30 feet) will directly overlie the proposed outlet culverts. The impact of the future road
embankments on the detention basin and the culverts is not included in this report.
The locations and descriptions of the site and proposed development are based upon a site
reconnaissance, and a review of the referenced plans. If project details vary significantly from those
described above, Geocon Incorporated should be contacted for review and additional analysis and/or
recommendations as required.
3. SOIL AND GEOLOGIC CONDITIONS
The mitigation area is underlain by alluvium and in rum by the Tertiary-aged Santiago Formation.
The approximate areal extent of these geologic units is indicated on the enclosed Geologic Map,
Figure 2. Geologic cross-sections are shown on Figures 3 and 4. Each of these soil units is described
below.
3.1 Alluvium (Qal)
Alluvial deposits were encountered in the canyon throughout the project area. The alluvium extended
to depths varying from approximately 46 feet near the center of the canyon in Boring B-3 to 19 feet
in Boring B-4. The consistency of the alluvium varied from clean, fine to coarse sand to sandy to
silty clay and clayey sand. The alluvium was generally soft and unconsolidated and therefore subject
to settlement under the increased load of the planned embankment. Portions of the alluvium may
also be subject to liquefaction during a seismic event. Settlement and liquefaction are addressed later
Project No. 06244-12-01 - 2 - July 6, 2000
in this report. Recommendations are included herein for remedial grading of the upper portion of the
alluvium.
3.2 Santiago Formation (Ts)
Siltstones and claystones of the Eocene-aged Santiago Formation were encountered underlying the
alluvium within the project's area. This unit was typically very stiff to hard and laminated in places.
The Santiago Formation should provide adequate support for additional loading from the planned fill
embankments.
4. GROUNDWATER
Groundwater was observed in all of the exploratory borings, as indicated on Table 4. Groundwater
conditions may vary considerably with seasonal precipitation and the resulting development of
perched water conditions within the alluvium and proposed fill soil.
TABLE 4
GROUNDWATER DATA
Borehole ID
B-l
B-2
B-3
B-4
B-5
B-6
Approximate Depth of Groundwater
Below Existing Ground Surface (feet)
3.5
8.5
9.0
11.0
11.0
8.0
Approximate Elevation of Groundwater
Above Mean Sea Level (feet)
33.5
51.5
58.0
58.0
54.0
52.0
5. GEOLOGIC HAZARDS
5.1 Faulting and Seismicity
A review of geologic literature, experience with the soil and geologic conditions in the general area,
and observations during the field investigation indicate that no active or potentially active faults
are located at the site. The nearest known "active" fault is the Rose Canyon Fault, located
approximately 7 miles west of the site. "Maximum credible" and "maximum probable" seismic
events of Magnitude 6.9 and 5.7, respectively, are postulated for the Rose Canyon Fault.
Corresponding maximum credible and maximum probable peak site accelerations of 0.30 g
Project No. 06244-12-01 -3-July 6, 2000
and 0.15 g, respectively, are estimated. Seismic parameters for the Rose Canyon Fault and other
regional faults were determined utilizing the computer program EQFAULT (Blake 1997) and are
summarized below.
TABLE 5.1
DETERMINISTIC SITE PARAMETERS FOR SELECTED FAULTS
Fault Name
Rose Canyon
Newport - Inglewood (offshore)
Elsinore - Julian
Elsinore - Temecula
Coronado Bank
Elsinore - Glen Ivy
Palos Verdes
Distance
From Site
(miles)
7
8
22
22
23
34
39
Maximum Credible Event
Maximum
Credible
(Mag.)
6.90
6.90
7.10
6.80
7.40
6.80
7.10
Peak Site
Acceleration
(g)
0.30
0.27
0.13
0.11
0.16
0.07
0.07
Maximum Probable Event
Maximum
Probable
(Mag.)
5.70
5.80
6.40
6.30
6.30
6.30
6.20
Peak Site
Acceleration
(g)
0.15
0.14
0.08
0.07
0.07
0.04
0.03
The site could be subjected to moderate to severe ground shaking from a seismic event on the Rose
Canyon Fault or other regional faults in the greater Southern California or northern Baja California
area.
5.2 Soil Liquefaction Potential
Liquefaction is a phenomenon in which loose, saturated, and relatively cohesionless sands lose shear
strength during strong ground motions. Liquefaction is typified by a total loss of shear strength in the
affected soil layer or layers due to a rapid buildup in pore water pressure. Liquefaction may result in
settlement, sand boils and/or rupture at the ground surface. Primary factors controlling the
development of liquefaction include:
The occurrence of a major earthquake
Intensity and duration of the earthquake
Magnitude of the ground acceleration at the site
Grain size characteristics of the subsurface soils
Relative density of subsurface soils
Saturation of subsurface soils
Project No. 06244-12-01 -4-July 6, 2000
The majority of the loose and soft alluvial deposits present below the groundwater table consisted of
sandy clays and clayey sands with fines content greater than 40 percent by mass. These cohesive
soils are not considered liquefiable. Loose, saturated sand layers were encountered in Borings B-3,
B-4, B-5, and B-6. These layers are generally considered liquefiable but are limited in thickness and
areal extent. Furthermore, consolidation and densification of the near-surface layers due to
embankment construction will significantly reduce the potential for liquefaction. Therefore, in the
event of a major seismic event in the vicinity of the site, isolated areas of liquefaction may result in
minor localized settlement but catastrophic failure due to liquefaction is not considered likely at
this site.
6. SETTLEMENT CONDITIONS
The settlement analyses of the alluvial soils is based on the general compressibility characteristics of
the soils encountered within the small-diameter borings. The determination of anticipated
magnitudes of settlement is subject to numerous interpolations and simplifying assumptions.
The amount of anticipated settlement that could occur is a function of thickness of the compressible
layers, and the compressibility characteristics of the layer and the amount of vertical load that will be
imposed on the compressible layer.
To aid in understanding the magnitude of settlement estimated to occur in developing the area,
Figure 5, Magnitude Settlement Curves, has been prepared. The curves on the figure present the total
settlement that would be expected for each boring location and for planned fill as well as potential
additional fill due to the road embankments. Theoretically, the alluvial deposits underlying the
proposed embankments (12 feet) will settle up to 6 to 8 inches. Based on our experience with similar
materials, the actual settlement may range from 50 to 80 percent of calculated settlement, due to
sample disturbance, laboratory testing methods and the variable nature of the alluvial deposits. The
time require for primary settlement is estimated to be approximately three to four months for soil
conditions within the area of Boring No. B-3. It should be noted, however, that the magnitude of
total settlement and associated time rate will not be uniform due to the variable thickness of the
underlying compressible materials.
7. EMBANKMENT STABILITY
Embankment stability was analyzed for both the upstream and downstream slopes of the proposed
detention basin embankments utilizing soil parameters developed from the field investigation,
Project No. 06244-12-01 -5- July 6,2000
laboratory testing and previous experience in the project area. These parameters are presented below.
It should be noted that the source of the material to be used in construction of the embankment fill is
not known at this time. However, it is anticipated that the source would be from the nearby Terrace
Deposits or the Santiago Formation.
TABLE 7.1
SLOPE STABILITY SOIL PARAMETERS
Soil Type
Compacted Fill (Qcf)
Alluvium (Qal) (clayey sand)
Alluvium (Qal2) (sandy clay)
Santiago Formation (Ts)
Unit Weight
(pcf)
130
130
130
130
Angle of Internal
Friction (degrees)
25
20
10
30
Cohesion
(psf)
250
200
300
500
The computer program SLOPE/W was utilized to analyze slope stability for the upstream and
downstream slopes. The approximate slope configurations analyzed are shown on Figures 3 and 4.
It is assumed that the recommended remedial grading will be performed as described herein. Both
slopes were analyzed for both static conditions and with a dynamic load generated by a bedrock
acceleration of 0.15g. Additionally, the upstream slopes were analyzed for a rapid drawdown
condition with the pool elevation at the highest anticipated water level. No steady-state seepage
analysis was performed as the maximum anticipated water retention period is 14 hours. The results
of the stability analyses are presented in Table 7.2. Details of the stability analyses and computer-
generated output are contained in Appendix C.
TABLE 7.2
SLOPE STABILITY ANALYSES — FACTORS OF SAFETY
Condition
Static
Seismic
Rapid Drawdown
Proposed Detention Basin Embankment
Upstream
1.96
1.28
1.57
Downstream
2.58
1.64
—
The stability analyses summarized above are for post-construction stability of the embankment as
proposed assuming that the recommended remedial grading measures are implemented. It is
Project No. 06244-12-01 -6-July 6, 2000
anticipated that stability will increase as the underlying alluvial deposits are densified by
consolidation.
8. CONSTRUCTION PROCEDURES
8.1 Remedial Grading
To reduce the magnitude of potential settlement and shorten the duration of the consolidation
process, it is recommended herein that the upper 6 to 8 feet of alluvial soil (approximately 3 feet
above water table) be removed and replaced prior to embankment construction. Remedial grading
should extend beyond the toe of the proposed embankment. The excavation for removals may begin
at approximately 12 to 16 feet beyond the embankment toe and slope at a 1:1 inclination until the
total removal depth is reached (see Figure 4). It is the contractor's responsibility to ensure excavation
stability. Remedial grading should extend around the entire perimeter of the proposed culvert,
including the headwall and outlet.
8.2 Culvert Construction
Conventional granular bedding materials will not be appropriate for RCP culvert construction; i.e.,
the pipe should be founded directly on the compacted fill. Therefore, in zones where compacted soil
fill cannot be properly placed, the pipe should be backfilled to the spring line with a lean concrete
grout with at least 2 sacks of cement per cubic yard of grout. The civil engineer should include
seepage rings in the design per regional standards.
Project No. 06244-12-01 - 7 - July 6, 2000
9. CONCLUSIONS AND RECOMMENDATIONS
9.1 General
9.1.1 No soil or geologic conditions were observed during the investigation or noted in the
review of the referenced documents that would preclude the construction of the proposed
detention basin embankment provided the recommendations of this report are followed.
9.1.2 A review of the log of Boring No. B-l, drilled west of the confluence of Agua Hedionda
and Calaveras Creeks, indicates a relatively shallow water table of 3.5 feet. It also shows
the presence of cohesionless sand near the surface. These soils are considered unsuitable
for the channel slopes due to the high potential for erosion.
9.1.3 The proposed embankment site is underlain by soft, saturated alluvial deposits subject to
settlement under surcharge load. Remedial grading of the upper portion of the alluvium is
recommended to decrease the magnitude of potential settlement and increase the stability
of the proposed embankment.
9.1.4 The construction of the proposed 72-inch culverts flowing to the south from the proposed
basin will require special design and construction considerations due to potential
settlement underlying its alignment. Recommendations for culvert design and construction
are included herein.
9.1.5 Groundwater was encountered in the area of the proposed embankments at elevations
ranging from approximately 51 to 58 feet above Mean Sea Level (MSL). Fluctuations in
the groundwater level should be anticipated due to seasonal precipitation. Special grading
recommendations are included herein to address constraints associated with high
groundwater levels.
9.1.6 The existing sewer and water lines should be protected against the potential settlement of
the underlying compressible alluvium. Further analysis may be needed in accordance with
the agency's requirements for the protection of the lines.
9.2 Channel Improvements
9.2.1 Information from the limited subsurface investigation indicated the presence of
cohesionless sands that may be exposed with channel slopes during improvements planned
Project No. 06244-12-01 - 8 - July 6, 2000
at the confluence of the two creeks. These granular materials are highly susceptible to
erosion during high water events.
9.2.2 Improvement plans should include the requirement for slope protection where these
materials are encountered. Mitigation procedures would include removal and replacement
with fine-grained (clayey) soils or placement of riprap stone with an underlying filter
blanket or filter fabric.
9.3 Grading
9.3.1 All grading should be performed in accordance with the Recommended Grading
Specifications contained in Appendix D and with applicable City of Carlsbad grading
ordinances. Where the recommendations of Appendix D conflict with this section of the
report, the recommendations of this section shall take precedence. All earthwork should be
performed in conjunction with the testing and observation services of Geocon
Incorporated.
9.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with
the Owner, Grading Contractor, Civil Engineer and Geotechnical Engineer in attendance.
Special soil handling, grading plans and instrumentation and monitoring programs can be
discussed at that time.
9.3.3 Grading should begin with the removal and exportation of vegetation and deleterious
matter from the area to be graded. Material to be used as fill should be free of organic
matter.
9.3.4 Prior to placing fill soil for the embankment, it is recommended that the upper portion of
the alluvium underlying the embankment alignment be removed to approximately 3 feet
above groundwater table and replaced by granular fill soil. Removals are estimated to be
approximately 6 to 8 feet below existing grade and should extend 12 to 16 feet beyond the
toe of the proposed embankments including headwalls. Removal excavations may be
limited to a maximum inclination of 1:1 (horizontal:vertical) (see Figure 3). Excavation
stability should be the responsibility of the grading contractor.
9.3.5 Saturated, clayey, alluvial soils excavated during site preparation should not be used
within the embankment fill unless mixed with on-site granular soils and dried to suitable
moisture content. The embankment fill should be constructed with soils meeting the
minimum strength requirements of 250 psf of cohesion and an angle of internal friction of
Project No. 06244-12-01 ^T July 6,2000
25 degrees. Grading operations should anticipate that excavated soils will require drying
by aeration and/or mixing with any drier near-surface soils. Embankment fill soils should
be approved by the soil engineer.
9.3.6 The proposed embankments may then be constructed with structural fill compacted in
layers. Layers of fill should be no thicker than will allow for adequate bonding and
compaction. All fill soil placed at the site, including fill soil outside of the embankments,
should be compacted to a minimum 90 percent relative compaction at or above optimum
moisture content in accordance with ASTM D 1557-91.
9.3.7 Granular bedding material is not considered suitable for RCP culvert construction. The
pipe should be founded directly on compacted fill. The zone around the pipe haunches
should be backfilled to the spring line with a lean concrete mix consisting of 2 sacks of
cement per cubic yard of grout. The civil engineer should include seepage rings in the
design per regional standards.
9.4 Slope Stability
9.4.1 Post-construction stability of the proposed embankments was analyzed for static and
seismic loading conditions and found to be adequately stable for both the upstream and
downstream slopes, provided that the recommended remedial grading is accomplished as
described herein. The upstream slope was also analyzed for a rapid-drawdown condition
and found to be adequately stable. Details of the stability analyses were previously
described in this report.
9.4.2 Surficial slope stability analysis indicates that the embankment slopes will have a factor of
safety in excess of 1.5 for the design heights (see Figure 6).
9.5 Slope Maintenance
9.5.1 Slopes that are steeper than 3:1 (horizontal:vertical) may, under conditions that are both
difficult to prevent and predict, be susceptible to near surface (surficial) slope instability.
The instability is typically limited to the outer three feet of a portion of the slope and does
not directly impact the improvements above or below the slope. The occurrence of
surficial instability is more prevalent on fill slopes and is usually preceded by a period of
heavy rainfall, excessive irrigation, or the migration of subsurface seepage. The
disturbance and/or loosening of the surficial soils, as might result from root growth, soil
expansion, excavation for irrigation lines and slope planting, or burrowing animal
Project No. 06244-12-01 - 10 - July 6, 2000
activities, may also be a significant contributing factor for surficial instability. It is,
therefore, recommended that, to the maximum extent practical: (a) disturbed/loosened
surficial soils be either removed or properly recompacted, (b) irrigation systems be
periodically inspected and maintained to eliminate leaks and excessive irrigation, (c)
surface drains on and adjacent to slopes be periodically maintained to preclude ponding or
erosion, and (d) rodent control. It should be noted that although the incorporation of the
above recommendations should reduce the potential for surficial slope instability, it will
not eliminate the possibility, and, therefore, it may be necessary to rebuild or repair a
portion of the project's slopes in the future.
9.6 Grading Plan Review
9.6.1 The soil engineer and engineering geologist should review the grading plans prior to
finalization to verify their compliance with the recommendations of this report and
determine the need for additional comments, recommendations and/or analysis.
Project No. 06244-12-01 -11 - July 6, 2000
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. 06244-12-01 July 6, 2000
SOURCE: 2000 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, WHETHER FOR PERSONAL USE OR
RESALE. WITHOUT PERMISSION
N
NO SCALE
GEOCON O
INCORPORATED ^SKr
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
PD/JMW DSK/DOOOD
VICINITY MAP
CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
DATE 07-06-2000 PROJECT NO. 06244 - 12 - 01 FIG. 1
X/R14/1DRAFTING/430/CARLBDB1
N50E
RANCHO CARLSBAD
DETENTION BASIN
CARLSBAD, CALIFORNIA
A
100' -i
< 50'-
ILI_1
UJ
0'-
B-3
CROSS-SECTION B-B1
SEE FIG. 4
GROUND SURFACE
PROPOSED FINISH GRADE B-4
Qal
Ts
Qal Qal
A'
r 100'
zo
I-
50' <
UJ
UJ
L 0'
LEGEND
Qal ALLUVIUM
7S SANTIAGO FORMATION
tee
SCALE : 1" = 50' (HORIZ. = VERT.)
CROSS-SECTION A-A'
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
PROJECT NO. 06244-12-01
FIGURE 3
DATE 07-06-2000
6244AS2 / RSS
RANCHO CARLSBAD
DETENTION BASIN
CARLSBAD, CALIFORNIA
B
80'-i
70'-
LU
_J
LU
60'-
50'-I
PROPOSED FINISH GRADE
100 YEAR PONDED WATER LEVEL
-GROUND SURFACE ••-:-'V.^ :•.•;.-/,-,:,; :v:::;.-,;o:v::7>^^:V-:vv^:V;--:vv^:r:;-:vv^:VvX-^>^
ALLUVIUM
WATER TABLE LEVEL WILL VARY SEASONALLY T
B1
-80'
-70'm
oz
L50'
SCALE : 1" = 10' (HORIZ. = VERT.)
CROSS-SECTION B-B'
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALFORNIA 92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
PROJECT NO. 06244-12-01
FIGURE 4
DATE 07-06-2000
6244AS / RSS
20
16
O
12
UJ
UJ
UJ
UJ
10 20 30
TOTAL HEIGHTS OF FILL (FEET)
50
GEOCON ®>
INCORPORATED ^SKr
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
AS / RSS DSK/EOOOO
MAGNITUDE SETTLEMENT CURVE
RANCHO CARLSBAD
DETENTION BASIN
CARLSBAD, CALIFORNIA
DATE 07-06-2000 PROJECT NO. 06244 - 12 - 01 FIG. 5
6422AS1 / RSS
Project No. 06244-12-01
ASSUMED CONDITIONS:
Slope Height
Depth of Saturation
Slope Inclination
Slope Angle
Unit Weight of Water
Total Unit Weight of Soil
Angle of Internal Friction
Apparent Cohesion
H = Infinite
Z = 3 feet
2:1 (Horizontal:Vertical)
i = 26.5 degrees
yw = 62.4 pounds per cubic foot
Yt = 130 pounds per cubic foot
c|) = 25 degrees
C = 250 pounds per square foot
Slope saturated to vertical depth Z below slope face.
Seepage forces parallel to slope face.
ANALYSIS:
ytZsm. icos i = 2.1
REFERENCES
(1) Haefeli, R. lite Stability of Slopes Acted Upon by Parallel Seepage,
Proc. Second International Conference, SMFE, Rotterdam, 1948, 1,
57-62.
(2) Skempton, A. W., and F. A. Delory, Stability of Natural Slopes in
London Clay, Proc. Fourth International Conference, SMFE, London,
1957,2,378-81.
SURFICIAL SLOPE STABILITY ANALYSIS - FILL SLOPES
DETENTION BASIN - RANCHO CARLSBAD
CARLSBAD, CALIFORNIA
Figure 6
APPENDIX A
FIELD INVESTIGATION
The field investigation was performed on April 13 and 14, 2000, and consisted of the excavation of 6
small-diameter hollow-stem-auger borings. The approximate locations of the exploratory borings,
except for Boring B-l, are shown on Figure 2, Geologic Map. Boring B-l was excavated
approximately 50 feet west of the confluence of Agua Hedionda and Calaveras Creeks.
The small-diameter borings were advanced to depths ranging from 26 to 51/4 feet below existing
grade. Relatively undisturbed samples were obtained by driving a 3-inch outside-diameter, split-tube
sampler into the "undisturbed" soil mass with blows from a 140-pound hammer falling a distance of
30 inches. The sampler was equipped with 1-inch- by 21/2-inch-diameter brass sample rings to
facilitate sampling and laboratory testing. Standard Penetration Tests (SPT) were performed at
selected intervals. SPT samples were obtained by driving a 2-inch split-tube sampler into the
"undisturbed" soil mass with blows from a 140-pound hammer falling 30 inches.
The soils encountered in the borings were visually examined, classified, and logged in general
accordance with American Society for Testing and Materials (ASTM) practice for Description and
Identification of Soils (Visual-Manual Procedure D 2844).
Logs of the borings are presented as Figures A-l through A-10. The logs indicate the general soil
types encountered, the depth at which samples were obtained and the laboratory determined in-place
dry density and moisture content of selected samples.
Project No. 06244-12-01 July 6, 2000
PROJECT NO. 06244-12-01
DEPTH
IN
FEET
U
_
- 2 -
-
- 4 -
- 6 -
- 8 -
- 10 -
- 12 -
- 14 -
- 16 -
- 18 -
- 20 -
- 22 -
—
- 24 -
~ —
SAMPLE
NO.
Bl-1
Bl-2
Bl-3
Bl-4
Bl-5
Bl-6
//
/
'
/
/
•'_
/
-
cr
z
s
//
/
//
/
./
/
//
/
/
-
)
1
<1
/ /
/
, /
/ •
•'-
-
•X
/
//
K.HI
<T
Q
Oa:CD
I
SOIL
CLASS
(USCS)
ML
SP
CL
SP
ML
BORING B 1
ELEV. (MSL.) 37 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Soft, moist, moderate yellowish-brown, Clayey
SILT/Silty CLAY, some fine sand
-Groundwater at 3.5 feet
Loose, wet/saturated, dark yellowish-brown, poorly
graded, fine to medium SAND
Stiff, wet to saturated, dark yellowish-brown, CLAY
with fine to medium sand; caliche stringers
Medium dense, wet, pale yellowish-brown, poorly
graded fine to medium SAND
SANTIAGO FORMATION
Hard, moist, pale olive to grayish-green, SILT, trace
fine sand
BORING TERMINATED AT 26 FEET
Sui^
^C *^ \Q™ r*"* oj
0_^N^
_
"
-
-
8
-
-
12
-
-
28
-
8
"-
—
"82/11"
>-
\~tS*t,
ft\ *
gjj^ •
o:~a
110.3
109.3
~
III *^a:~
?£
*-ou
18.9
20.1
Figure A-l, Log of Boring B 1 RCDB
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL E . . . STANDARD PENETRATION TEST •... DRIVE SAMPLE (UNDISTURBED)
... DISTURBED OR BAG SAMPLE ... CHUNK SAMPLE Y. ... 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. 06244-12-01
DEPTH
IN
FEET
U
- 2 -
-
- 4 -
- 6 -
- 8 -
1U
- 12 -
- 14 -
- 16 -
- 18 -
- 20 -
- 22 -
24
- 26 -
- 28 -
SAMPLE
NO.
B2-1 1
B2-2 I
1
B2-3
B2-4
B2-5 1
CDo
O
t—H_J
-
. -
- . • .
%?
\fy
'$A-$
•-. --j
:•]•.
";•-}"
::j-
- {-i-
- -|. .%
^
a:
^p-i
i
0
g
^
SOIL
CLASS
(USCS)
ML
CL-SM
SP-SM
CL
BORING B 2
ELEV. (MSL.) 60 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Firm, dry to damp, dark yellowish-brown, Sandy
SILT
Firm, damp, very pale orange and grayish-orange
CLAY, alternating with Silty SAND and Sandy SILT
-Groundwater table at 8.5 feet
Medium dense, wet/saturated, grayish-orange, poorly
graded, slightly Silty, fine to medium SAND
-Runs up inside augers
Very firm, wet to saturated, pale and dark
yellowish-brown and light olive-gray CLAY, some
fine sand
ZlU~Si CJ i *t 2T|
Sfcco
ijj'~'o
Lu^oQ- ^
16
30
35
34
26
>-
^™^NJ"J *
211-
h>J ^
^ ft_
S^
113.9
115.9
*
^L|ftr*^^
SzHygg
U
16.7
17.9
Figure A-2, Log of Boring B 2 RCDB
SAMPLE SYMBOLS HI... SAMPLING UNSUCCESSFUL E... STANDARD PENETRATION TEST •... DRIVE SAMPLE (UNDISTURBED)
... DISTURBED OR BAG SAMPLE EU . . . CHUNK SAMPLE Z ... 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. 06244-12-01
DEPTH
IN
FEET
• 30
- 32 -
-
- 34 -
- 36 -
-
_ -30 _
SAMPLE
NO.
B2-6
B2-7 LITHOLOGY//^////
///
y///,H//
/ /
/ /
/ /GROUNDUATER ISOIL
CLASS
(USCS)
CL
CL
BORING B 2
ELEV. (MSL.) 60 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM (Cont.)
Very stiff, wet, light olive-gray, moderate
yellowish-brown and yellowish-gray CLAY, with
laminae of Sandy CLAY
SANTIAGO FORMATION
Hard, damp, mottled pale olive and light olive-brown,
CLAY
-Refusal ^
BORING TERMINATED AT 38 FEET PENETRATIONRESISTANCE(BLOWS/FT.)29
—
-
-
50
-DRY DENSITY(P.C.F.)101.1 MOISTURECONTENT (X)25.5
Figure A-3, Log of Boring B 2 RCDB
SAMPLE SYMBOLS D ... SAMPLING UNSUCCESSFUL
§1 ... DISTURBED OR BAG SAMPLE
B . . . STANDARD PENETRATION TEST • ... DRIVE SAMPLE (UNDISTURBED)
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.
PROJECT NO. 06244-12-01
DEPTH
IN
FEET
- 2 -
- 4 -
—
- 6 -
- 8 -
-
- 10 -
-
- 12 -
- 14 -
- 16 -
- 18 -
-
- 20 -
- 22 -
-,
- 24 -
-
- 26 -_
- 28 -
SAMPLE
NO.
B3-1
B3-2
B3-3
B3-4
B3-5
>-CDo
O
(—
H_l
^
)
}
<J
(
/
)
J
)/\/y
/i/vA/yMsM/'Yy'YYM/'YY\
:1.
:-.;-
•ij..-. •
-' - . "
o:LUi—
3a
oa:CD
<!
\
((/
^}
(i
(iii
yyy
\-
(
(
SOIL
CLASS
(USCS)
ML
CL
SM
ML
SP
BORING B 3
ELEV. (MSL.) 67 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Very stiff, damp, dark yellowish-brown SILT, some
fine to medium sand
-Groundwater table at 9 feet
-6" thick Silty SAND
Firm, damp, pale to dark yellowish-brown Silty
CLAY, with fine sand
Medium dense, moist to wet, dark yellowish-brown,
Silty, fine SAND
Firm, damp, dark yellowish-brown SILT
Medium dense, moist to wet, pale yellowish-brown,
poorly graded SAND
z /-*oW •
In Ho
u^cdQ. ^
18
5
18
8
- 2^
^,i—^
|u
g~
113.6
106 4
^
luSCK
= 1-cogj
^^ ^»^~ 1^o
18.7
21 4
Figure A-4, Log of Boring B 3 RCDB
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL D ... STANDARD PENETRATION TEST I... DRIVE SAMPLE (UNDISTURBED)
H ... DISTURBED OR BAG SAMPLE B ... CHUNK SAMPLE I ... 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. 06244-12-01
DEPTH
IN
FEET
30
- 32 -
_ _
- 34 -
- —
- 36 -
- 38 -
- 40 -
- 42 -
- 44 -
-
- 46 -
-
- 48 -
- 50 -
SAMPLE
NO.
B3-6
B3-7
B3-8
B3-9
B3-10
>-cso
o
H_1
-
- " „
/t/j/F/yyv/y/y
xi/T/T/
x/%
/j/j/y
/yVy
W/W//\A/\/W/W(X,' Yy //vyyA/Vy
W
W
AAA,
//
s
-/ '/
'//-
/
//-
a:
<r
a
oa:
SOIL
CLASS
(USCS)
SP
CL
CL/SC
If* y*VT^ YTk. T^""1 T* ^BOREVG B 3
ELEV. (MSL.) 67 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM (Cont.) r> Medium dense, wet, pale to moderate /l
t yellowish-brown, poorly graded SAND '
Very stiff, damp, pale to moderate yellowish-brown,
Silty CLAY, some fine sand
-Mottled dark yellowish-orange
-Yellowish-gray to light olive-gray
SANTIAGO FORMATION
Hard, damp, yellowish-gray to light olive-gray, Sandy
CLAY/Clayey SAND
BORING TERMINATED AT 51.5 FEET
GROUNDWATER ENCOUNTERED AT 9 FEET
Z s*-
go,.!!&jS
UjHo
LUJJJCQ
13
-
_
~
19
"
-
19
-
43
-
-
~26/9"
j_
h- ^
tn *
gjj
™~ •
^__CL
0£~^O
112.5
^uj^53,_
HiiiEg
CJ
19.5
- Figure A-5, Log of Boring B 3 RCDB
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL C... STANDARD PENETRATION TEST I... DRIVE SAMPLE (UNDISTURBED)
[Si ... 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.
PROJECT NO. 06244-12-01
DEPTH
IN
FEET
U
- 2 -
- 4 -
6
- 8 -
- 10 -
- 12 -
14
- 16 -
- 18 -
- 20 -
- 22 -
- 24 -
-
- 26 -1
SAMPLE
NO.
B4-1
B4-2
B4-3
B4-4
B4-5
-
-
-'
-
-
•
ti
\\////
ii(-
i
H
'
\
N
•
-
-
-I
]
j
-
1
H%1I$
11
-11
1
•r
.
. -
1- '1.r.-fl%i
%.%i/\<
ffLUt—<T
a
Oce
CD
T
SOIL
CLASS
(USCS)
SM
ML
SM
CL
ML/CL
BORING B 4
ELEV. (MSL.) 69 DATE COMPLETED 4/13/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Loose, wet, light olive-gray to dark yellowish-brown,Silty, fine to medium SAND
Becomes soft, Sandy SILT, dark yellowish-brown
-Groundwater table at 1 1 feet
Loose, saturated, dark yellowish-brown, Silty SAND
-Clay at tip
SANTIAGO FORMATION
Hard, moist, light greenish-gray, Sandy CLAYSTONE
Hard, moist, light greenish-gray, very thinly bedded
to laminated SILT/CLAYSTONE, with sand in places
BORING TERMINATED AT 26.5 FEET
z ^>O(j •
Ilk
^ H4rt
u^mQ. ^
-
5
—
-
19
-
11
—
35
-
-
32
-
^.
k~
fc
"^ •
^ ^_
a
114.2
1 1| ^
wgj
Eou
19.5
Figure A-6, Log of Boring B 4 RCDB
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL E ... STANDARD PENETRATION TEST
H ... DISTURBED OR BAG SAMPLE B ... CHUNK SAMPLE
... DRIVE SAMPLE (UNDISTURBED)
... 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. 06244-12-01
DEPTH
IN
FEET
A —U
- 2 -
- 4 -
-
- 6 -
-
- 8 -
- 10 -
- 12 -
14
- 16 -
- 18 -
- 20 -
_
- 22 -
- 24 -
- 26 -
-
SAMPLE
NO.
B5-1
B5-2
B5-3
B5-4
B5-5
>-COo
O
1—Hi
" 1 " "I
ri
:l}'l"
4 "" . I-•i j- !
'\]\}i.
J:}-i-
;•)]-[•
m§••'/vVvA/yV/yVy/yvy<i%
X/i-L/r
ytyT
ir ~y
i/l y/i t/[t/l -y
A- l/l"X- ',-/f /
%.
•
ryLUi—<r
Q
iorv
CO
T
SOIL
CLASS
(USCS)
SM
CL
VIL/CL
SM
SM
BORING B 5
ELEV. (MSL.) 65 DATE COMPLETED 4/14/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Medium dense, damp, moderate yellowish-brown,
Silty, fine to medium SAND
-Silt, 6" thick
Stiff, saturated, dark yellowish-brown, Sandy CLAY
-Groundwater table at 1 1 feet
Becomes stiff, saturated, dark yellowish-brown
SILT/CLAY, some fine sand
Becomes firm, saturated, grayish-orange to moderate
yellowish-brown Silty, Clayey SAND with fine
SAND, laminated in places
Medium dense, saturated, grayish-brown
-Becomes Clayey SAND
SANTIAGO FORMATION
Z s*Ro.*M^h-
^C *^ \Q£ //* WJ
u^mQ- ^
_
-
15
-
-
15
_
-
15
-
8
—
—
30
-
-
^i— /^
iH^ «Q_
a
113.3
110.0
/•N
fc*HrH
^~ ^^u
20.2
20.3
Figure A-7, Log of Boring B 5 RCDB
SAMPLE SYMBOLS D ... SAMPLING UNSUCCESSFUL
H ... DISTURBED OR BAG SAMPLE
C ... STANDARD PENETRATION TEST • ... DRIVE SAMPLE (UNDISTURBED)
B ... CHUNK SAMPLE 3E ... 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. 06244-12-01
DEPTH
IN
FEET
- 30
- 32 -
-
- 34 -
- 36 -
SAMPLE
NO.
BS-6 1
J LITHOL06Ym,Y/MWJb.
•» pfM GROUNDUATERSOIL
CLASS
(USCS)
CL
BORING B 5
ELEV. (MSL.) 65 DATE COMPLETED 4/14/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
SANTIAGO FORMATION
Hard, moist, yellowish-gray to very pale orange Sandy
CLAYSTONE
-Becomes gravelly
-Difficulty drilling from 30-35 feet
BORING TERMINATED AT 36 FEET PENETRATIONRESISTANCE(BLOWS/FT.)34
-
-
-
68/11"
kgot MOISTURECONTENT OC>«. Figure A-8, Log of Boring B 5 RCDB
SAMPLE SYMBOLS D ... SAMPLING UNSUCCESSFUL B ... STANDARD PENETRATION TEST • ... DRIVE SAMPLE (UNDISTURBED)
H ... 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.
PROJECT NO. 06244-12-01
DEPTH
IN
FEET
f\0
- 2 -
- 4 -
- 6
- 8 -
-
- 10 -
- 12 -
- 14 -
-
16
- 18 -
- 20 -
- 22 -
_
- 24
_
- 26 -
-
- 28 -
SAMPLE
NO.
B6-1 1
B6-2 I
B6-3
B6-4 1
B6-5
>-
o
o
H_1
•Vh\ \--\\-\\-\
i
/i- 1/• j/T •
.'\A •A i/
r A
\A '/
I:}i
.:i-[;
1-1•y\.
]]:
n•b'\\.
- - -
%/i/T/AA/AA/AA/A\A/A//
•
•
Y/\Y
Y
Y•
-
-
•
t
t-
?/
Y,
(KLU
<T
a
oa:CD
=
SOIL
CLASS
(USCS)
SM
ML/CL
SM/ML
SM
SP
ML-CL
BORING B 6
ELEV. (MSL.) 60 DATE COMPLETED 4/14/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
ALLUVIUM
Loose, damp, pale yellowish-brown, Silty, fine to
medium SAND
Firm to stiff, moist, dark yellowish-brown
SILT/CLAY, with fine sand
-Groundwater table at 8 feet
Stiff/medium dense, moist to wet, pale
yellowish-brown, Silty SAND/Sandy SILT
-6" thick, plastic clay
Loose, saturated, moderate yellowish-brown, Silty,
fine to medium SAND
-Becomes medium dense
Medium dense, wet, moderate yellowish-brown,
poorly graded, fine to medium SAND
SANTIAGO FORMATION
Very stiff, moist, light olive-gray, SILT/CLAY, some
fine sand
Z f^O f* •
^C •* \Q£ tin WJ
j"T |_ ji*
LjJ JW ^Q
tL ^
-
7
11
5
24
14
g
^t—^
tn *
gjjj
O ^>i
109.7
^^
iij-*ty
l_^
M|^|
gg
U
21.0
Figure A-9, Log of Boring B 6 RCDB
SAMPLE SYMBOLS D ... SAMPLING UNSUCCESSFUL E ... STANDARD PENETRATION TEST • ... DRIVE SAMPLE (UNDISTURBED)
... DISTURBED OR BAG SAMPLE ... CHUNK SAMPLE JL ... 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. 06244-12-01
DEPTH
IN
FEET
30
- 32 -
34
SAMPLE
NO.
CDo
o
H_1
B6-6 |||P[HH
B6-7 I
y$M
w/%,
a:HI
<r
3
CD
SOIL
CLASS
(USCS)
VIL-CL
BORING B 6
ELEV. (MSL.) 60 DATE COMPLETED 4/14/00
EQUIPMENT CME 55
MATERIAL DESCRIPTION
SANTIAGO FORMATION (Cont.)
Becomes hard, moist, light olive-gray, Silty
CLAYSTONE
BORING TERMINATED AT 34 FEET
iu~
i|
|£s
24
~50/5"
>
^^^%
gj
!~
111.7
~
^J0£.
|l
°|
CJ
18.6
Figure A-10, Log of Boring B 6 RCDB
SAMPLE SYMBOLS D... SAMPLING UNSUCCESSFUL C... STANDARD PENETRATION TEST I... DRIVE SAMPLE (UNDISTURBED)
® ... 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 B
LABORATORY TESTING
Laboratory tests were performed in general accordance with test methods of the American Society
For Testing and Materials (ASTM) or other suggested procedures. Selected samples were tested for
their in-place dry density, moisture content, shear strength, consolidation, compaction and gradation.
The results of our laboratory tests are presented in tabular and graphical forms hereinafter. The
in-place dry density and moisture content characteristics are presented on the logs of the exploratory
borings.
TABLE B-l
SUMMARY OF DIRECT SHEAR TEST RESULTS
Sample No.
Bl-2
B6-2
Dry Density
(pcf)
112.4
109.7
Moisture Content
(%)
18.1
21.0
Unit Cohesion
(psf)
60
1050
Angle of Shear
Resistance (degrees)
42
10
TABLE B-ll
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557-91
Sample
No.
Bl-1
Description
Yellowish brown, Clayey SAND
Maximum
Dry Density
(pcf)
128.1
Optimum
Moisture Content
(% dry wt.)
8.6
Project No. 06244-12-01 July 6, 2000
PROJECT NO. 06244-12-01
3
80
I 7R5 70
HUJ
CQ
uj 50
HU_
£ 40
uj 30
20
10
0
III
. A
GRAVEL
COARSE FINE
1-1/2" 3/4" 3/8'
1
SAND
:OARSE
4
f-^|l
MEDIUM FINE SILT OR CLAY
U. S. STANDARD SffiVE SIZE
16 30 500 | 20 40 60 100 200
N:
^^
4.
^
S S
•«
A
••
S
\^
•4
V
X
\
^B
i\
\\>
i
-x
v\
\V
'!
1
.
'v
h
^v.
\s\,
^S
>k •v x^^x^>!
10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
SAMPLE
B2-3
B3-2
B3-4
Depth (ft)
15.0
10.0
20.0
CLASSD7ICATION
(SP-SM) Grayish-orange, slightly Silty SAND
(CL) Yellowish-brown Silty CLAY
(SM) Yellowish-brown, Silty SAND
»JATWC LL PL PI
GRADATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-l
PROJECT NO. 06244-12-01
3
100
on7<O
80
I 70
H111: ™CD
| 50
HU.
H 40
LU
g 30
20
10
0
GRAVEL
COARSE FINE
' 1-1/2" 3/4" 3/£"r-5*^'
SAND
COARSE
4
fl
am fl
MEDIUM FINE SILT OR CLAY
U. S. STANDARD SDZVE SIZE
16 30 503 20 40 60 100 200
^1s ^i^r
iitS
^^
Ls'
i
k
Vs
\
;
\
i;
\
10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
•IX
A
SAMPLE
B3-8
B5-2
B5-4
Depth (ft)
40.0
10.0
20.0
CLASSIFICATION
(CL) Yellowish-brown, Silty CLAY
(CL) Yellowish-brown, Sandy CLAY
(SM) Grayish-brown, Silty SAND
*ATWC LL PL PI
GRADATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-2
PROJECT NO. 06244-12-01
PERCENT CONSOLIDATION®rv> Qcoo)*.rosw*»SAMPLE NO. B2-2
» ^.•• •—•^•^•«• i
t
i
•••
^ta
•«
««
*»
^
•H
^
"I
ta
\
"— '
X
*• ..
N
"« -»
x
~~-
s
^ta s•VMa*i
1 1 10 100
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
113.9
16.7
Initial Saturation (%)
Sample Saturated at (ksf)
96.8
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-3
PROJECT NO. 06244-12-01
PERCENT CONSOLIDATION^ i_t ii<s>ro ocoo>-p»ruQru*>SAMPLE NO. B2-5
*^
"^•^1
1
^m
^
^-i
•••
^
•••••
*i
•N
\1
^-^
^,
*
N
i*^*«
\
•**,
S
••.
L\
•«,^1
1 1 10 100
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
115.9
17.9
Initial Saturation (%)
Sample Saturated at (ksf)
100+
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-4
PROJECT NO. 06244-12-01
PERCENT CONSOLIDATIONi_> >-> iiroscoo)*»ruoro*»SAMPLE NO. B3-3
•^-— .*--».
— — .-4
I
**i
— .
^
•••
*•
•*•
•«
*«
"1
^
"^N
---^
N \
•*-.
\
••••
s
**^*^,V1
0.1 1 10 100
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
113.6
18.7
Initial Saturation (%)
Sample Saturated at (ksf)
100+
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA•w
RCDB Figure B-5
PROJECT NO. 06244-12-01
SAMPLE NO. B3-7
PERCENT CONSOLIDATION10 100
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
112.5
19.5
Initial Saturation (%)
Sample Saturated at (ksf)
100+
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALD7ORNIA
RCDB Figure B-6
PROJECT NO. 06244-12-01
<Ea
otn
ou
LUCJce
UJa.
SAMPLE NO. B4-2
-4
-2
0
6
10
10
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
114.2
19.5
Initial Saturation (%)
Sample Saturated at (ksf)
100
100+
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-7
PROJECT NO. 06244-12-01
oen
I
LUUce
UJ0.
SAMPLE NO. B5-3
-4
-2
8
10
120.1
\
10
APPLIED PRESSURE (ksf)
Initial Dry Density (pcf)
Initial Water Content (%)
113.3
20.2
Initial Saturation (%)
Sample Saturated at (ksf)
L00
100+
.5
CONSOLIDATION CURVE
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
RCDB Figure B-8
I i i
Sample B2-2 (TR 4000)
-2750
-2850
10
Square Root Time (min)
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCONIMOOBTOBATMD • PROJECT NO.IDATEOT-oeaxx
06244 -12 - 016«o FUH»J MM - UN MOO. cuKMk na-»»IHCMI5155HK» • FAX in UMW SHEET 1 OF 7 lB-9
I i I I 1
Sample B2-5 (TR 4000)
-2650
o>c'•5
8 -2700
-2750
Square Root Time (min)
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON i"o7-06-200C
06244 -12 - 01
SHEET 2 OF 7 B-10
I i I i I I II
Sample B3-3 (TR 2000)
-2400
-2500
4 6
Square Root Time (min)
10
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON
IMOO*»0»AT»B
IDATE
07-06-2
06244 -12 - 01
- UM OKO. CUMMH naiint 1B-11
I i i i I i I I i I i i i t
Sample B3-3 (TR 4000)
-2450
-2500
D)C
ra
5
-2550
-2600
10
Square Root Time (min)
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON
1HOO»FO»AT»D
1*07-06-2000
• PROJECT* 06244-12-01 \fauK
I CUCCT A r»c t 1B-12
Sample B3-7 (TR 4000)
-1275
-1375
10
Square Root Time (min)
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GBOCON I°07-O6-2000
06244 - 12 - 01
-13
Sample B4-2 (TR 2000)
-1750
-1850
4 6
Square Root Time (min)
10
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON IDATE
07-06-200O
06244 -12 - 01 FIGURE
14
i I
Sample B5-3 (TR 4000)
-1700
-1750
D)C
Bra0)o:
"n
5
-1800
-1850
10
Square Root Time (min)
TIME RATE GRAPH
RANCHO CARLSBAD DETENTION
CARLSBAD/CALIFORNIA
GEOCON AIHOOBFOKATaD ^^
««0 HAtOU DM • UN MOO. OintMt MU1-H74moMut amm • MX «» «M»
BASIN
"" 107-06-2000
P""CTNO 06244
SHEET? OF 7
-12-01 FKM"
B-16
APPENDIX C
SLOPE STABILITY ANALYSES
Slope stability analyses for the proposed detention basin embankments were performed utilizing the
SLOPE/W computer program. The critical cross-section was determined for the embankment slope
and analyzed under static, seismic, and rapid drawdown conditions (upstream slopes). In determining
embankment stability, it is assumed that the remedial grading recommended herein will be
accomplished.
Cross-sections were based on the referenced plans provided (Figure 2) and data obtained during the
field investigation. The critical cross-section utilized in the analyses is depicted as Figure 4 Cross-
Section B-B'. Soil parameters were developed from data collected during the field investigation and
from the laboratory testing. The water levels were set at the design elevations given on the
referenced grading exhibit. Analyses were performed for the upstream and downstream slope for
static conditions and with a seismic load generated from a bedrock acceleration of 0.15g. The
upstream slope was analyzed under rapid drawdown conditions. The cross-sections analyzed and the
analyses results are graphically depicted on Figures C-l through C-5.
Project No. 06244-12-01 July 6, 2000
i i I i
CO
_o
0
100
90
80
70
60
50
40
30
20
10
0
•2.333
Rancho Carlsbad
Detention Basin
downsteam slope
static
Ts
-10-4 2 8 142026323844505662687480869298104
distance(ft)
SLOPE STABILITY ANALYSIS
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON
GKHKIMCAL OCNUUHnmo tumaa MM • UK woo.ma* isi sswai. FAX in UMW
107-06-2000
"agc™a 06244-12-01 I""8
|C-1RHFFT 1 DF 5 I
i i i till f
03
jy
CD
100
90
80
70
60
50
40
30
20
10
0
1.637
Ranchp Carlsbad
Detention Basin
downsteam slope
seismic loading
Ts
-10-4 2 8 142026323844505662687480869298104
distance(ft)
SLOPE STABILITY ANALYSIS
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON iPftOJECT NO.06244
»w nuccu MM - SAN Moo. cufotMk ma -tnt
07-06-2000
-12-01 I"5"*lr.9
I i t 1 I I 1
100
90
Ranchp Carlsbad
Detention Basin
upstream slope
static
-10-4 2 8 142026323844505662687480869298104
distance(ft)
SLOPE STABILITY ANALYSIS
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCONIMP oapomAT»B IDATE
07-06-2
06244-12-01 |F1GURE
lC-3
fill
c
03
_0)
CD
100
90
80
70
60
50
40
30
20
10
0
Ranchp Carlsbad
Detention Basin
upstream slope
seismic loading
Ts
-10-4 2 8 142026323844505662687480869298104
distance(ft)
SLOPE STABILITY ANALYSIS
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON I SCALE io7-06-2000
IP^CTMO Q6344.12.Q1 |»a«E
I „ C-4
I i I I f I 1 I i I i I: 1 I I I i 1 I J I I I l
03
0)
CD
100
90
80
70
60
50
40
30
20
10
0
Ranchp Carlsbad
Detention Basin
upstream slope
Rapid Drawdown
Ts
-10-4 2 8 142026323844505662687480869298104
distance(ft)
SLOPE STABILITY ANALYSIS
RANCHO CARLSBAD DETENTION BASIN
CARLSBAD, CALIFORNIA
GEOCON 10ATE
_07-06-2QOQ
06244-12-01 r
monANniNM-uMMaoiouicMtnBi-im •IHQMiSil»MOa.FAXU>S9Mm I CUCCT c n=C-5
^t^lfi^^^!lj^'?>*"|^
APPENDIX D
RECOMMENDED GRADING SPECIFICATIONS
FOR
RANCHO CARLSBAD—DETENTION BASIN
CARLSBAD, CALIFORNIA
PROJECT NO. 06244-12-01
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 (horizontahvertical) 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 groundwater 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"
SeeNoteT See Note 2-
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 die maximum laboratory dry density as
determined in accordance with ASTM Dl557-91. 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.
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
GI rev. 8/98
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 D1196-64, 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.
7.62. 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 O.S 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