HomeMy WebLinkAboutSDP 05-18; ECR CORPORATE CENTER; UPDATE GEOTECHNICAL REPORT; 2007-03-24j 4)
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UPDATE
GEOTECHNICAL REPORT
VILLAGES OF LA COSTA -
THE GREENS
NEIGHBORHOOD 1.01
ECR CORPORATE CENTER L. P.
CARLSBAD, CALIFORNIA
PREPARED FOR
CARLTAS INVESTMENTS, LLP
CARLSBAD, CALIFORNIA a
MARCH 23, 2007
PROJECT NO. 06403-52-31 cw
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
Project No. 06403-52-31
1 March 23, 2007
Caritas Investments, L. P.
5600 Avenida Encinás, Suite 100
Carlsbad, California 92008
Attention: Mr. John C. White
Subject: VILLAGES OF LA COSTA - THE. GREENS
NEIGHBORHOOD 1.01
ERC CORPORATE CENTER L.P.
CARLSBAD, CALIFORNIA
UPDATE GEOTECHNICAL REPORT
Dear Mr. White:
In accordance with your authorization of our Proposal No. LG-07064 dated February 22, 2007, we
have prepared this update geotechnical report for the subject site. The accompanying report presents
the results of our study and our conclusions and recommendations pertaining to the geotechnical
aspects of project development.
We understand the existing sheet-graded pad will be fine graded to support two, two-story structures
along with associated improvements. The buildings are anticipated to consist of concrete tilt-up
structures supported by conventional continuous and/or isolated spread footings with slab-on-grade
construction. Based on the results of this study, it is our opinion that the site can be developed as
planned, provided the recommendations of this report are followed.
Should 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 INCORPORATED
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ENGINEERING
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No. 66915
(6/del) Addressee
6960 Flanders Drive • Son Diego, California 92121-2974 • Telephone (858) 5586900 5 Fax (858) 558-6159
TABLE OF CONTENTS
PURPOSE AND SCOPE .1
PREVIOUS SITE DEVELOPMENT .............................................................................................. 1
SITE AND PROJECT DESCRIPTION...........................................................................................2
SOIL AND GEOLOGIC CONDITIONS ........................................................................................2
4.1 Compacted Fill (Qcf).............................................................................................................2
4.2 Undocumented Fill (Qudf)....................................................................................................2
4.3 Lindavista Formation (Qln) ..................................................................................... . ............. 3
4.4 Santiago Formation (Ts)........................................................................................................3
GROUNDWATER..........................................................................................................................3
GEOLOGIC HAZARDS .................................................................................................................3
6.1 Faulting and Seismicity.........................................................................................................3
6.2 Liquefaction...........................................................................................................................4
6.3 Landslides..............................................................................................................................4
CONCLUSIONS AND RECOMMENDATIONS...........................................................................5
7.1 General .................................................................................................................................... 5
7.2 Soil and Excavation Characteristics ....................................................................................... 5
7.3 Grading .................................................................................................................................. 5
7.4 Seismic Design......................................................................................................................7
7.5 Corrosive Potential................................................................................................................8
7.6 Subdrains...............................................................................................................................8
7.7 Slopes .................................................................................................................................... :8
7.8 Foundation Recommendations ............................................... . ....................... . ...................... 9
7.9 Concrete Slabs-on-Grade Recommendations ....................................................................... 10
7.10 Retaining Walls and Lateral Loads ....... . ............................................................................... 11
7.11 Preliminary Flexible Pavement Recommendations.............................................................12
7.12 Slope Maintenance ............................................................................................................... 13
7.13 Site Drainage.......................................................................................................................14
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Typical Retaining Wall Drain Detail
Figure 3, Wall/Column Footing Dimension Detail
Figure 4, Retaining Wall Drain Detail
APPENDIX A
LABORATORY RESULTS
Table A-I, Summary of Finish Grade Expansion Index Test Results
Table A-H, Summary of Laboratory Water-Soluble Sulfate Test Results
APPENDIX B
RECOMMENDED GRADING SPECIFICATIONS
UPDATE GEOTECHNICAL REPORT
1. PURPOSE AND SCOPE
This report presents the results of an update geotechnical study for the proposed development of the
of Neighborhood 1.01 located in the Villages of La Costa - The Greens in Carlsbad, California (see
Vicinity Map, Figure 1). The purpose of this update report was to evaluate the soils and geologic
conditions within the site and provide specific geotechnical recommendations pertaining to the
ultimate development of the property as proposed.
The scope of the study included a site visit to observe whether the lot is essentially the same as it was
upon the completion of mass grading operations and review of the following reports and plan
associated with the site:
Final Report of Testing and Observation Services Performed During Site Grading, Villages
of La Costa - The Greens, Neighborhoods 1. 01, Carlsbad, California, prepared by Geocon
Incorporated, dated March 13, 2006 (Project No. 06403-52-22).
Update Soil and Geological Investigation, Volume I and II, Villages of La Costa - The
Greens, Carlsbad, California, prepared by Geocon Incorporated, dated June 25, 2001
(Project No. 06403-12-03).
Preliminary Grading Plan, TRI City Wellness Center, ECR Corporate Center, prepared by
RBF Consulting, dated March 7, 2007
The descriptions of the soil and geologic conditions and proposed development described herein are
based on .review of the referenced reports and plan, and observations made during mass grading
operations for Neighborhood 1.01 of the Villages of La Costa - The Greens development.
2. PREVIOUS SITE DEVELOPMENT
Mass grading for the site occurred between December 2005 and January 2006. The grading was
performed in conjunction with the compaction testing and observation services of 'Geocon
Incorporated. Test results as well as professional opinions pertaining to the mass grading are
summarized in the referenced geotechnical report (Reference No. 1). The As-Graded geologic
conditions in Neighborhood 1.01 consist of compacted fill, undocumented fill, and Santiago
Formation exposed at grade.
Figure 2 (Geologic Map, map pocket) is a copy of the development plan showing the sheet-graded
pad and proposed development. The map has been modified to include the as-graded geologic
information presented in the referenced geotechnical report dated March 13, 2006. This exhibit was
the basis for our evaluation and recommendations pertaining to project development.
Project No. 06403-52-30 - 1- Much 23, 2007
SITE AND PROJECT DESCRIPTION
The irregular-shaped site consists of a previously graded vacant lot. Neighborhood 1.02 and
undeveloped land bound the site on the south and east, respectively. El. Camino Real borders the
-
property to the west. Bressi Ranch is located to the north of the project. Prior to grading, topography
within the subject neighborhood varied from gently sloping to moderately steep hillside terrain.
Fill slopes were constructed with a maximum height of 35 feet. Topographically, the sheet-graded
pad slopes to southeast with elevations varying from approximately 308 above Mean Sea Level
(MSL) to approximately 302 MSL.
The referenced site plan indicates the site will be developed to support building pads and
infrastructure improvements. It is anticipated that the structures will be founded on conventional
continuous and isolated spread foundations with slab-on-grade floors. The majority of parking lot
traffic is anticipated to consist of cars and light trucks. Grading is expected to consist of cuts and fills
generally less than 3 feet to create level building pads.
The descriptions contained herein are based upon the site reconnaissance and a review of the
referenced reports and plan. If project details vary significantly from those outlined herein, Geocon
Incorporated should be notified for review and possible revisions to this report prior to final design
SOIL AND GEOLOGIC CONDITIONS
Compacted fill, undocumented fill, the Santiago Formation, and Lindavista Formation underlie the
site. The as-graded geology is presented on Figure 2. The soil types and geologic units are discussed
below.
4.1 Compacted Fill (Qcf)
Fill materials comprise the eastern and southern margins half of the site and generally consist of silty
sand. The maximum fill thickness is approximately 25 feet. Fill soil was placed in conjunction with
the observation and testing services of Geocon Incorporated, which are summarized in the above-
referenced geotechnical report dated March 13, 2006. The compacted fill soil is considered suitable
for support of the proposed structure and ancillary improvements.
4.2 Undocumented Fill (Qudf)
Undocumented fill associated with an existing (in service) 30 inch, high pressure gas line is located
along the western boundary, adjacent to El Camino Real. Previous grading in this vicinity was limited
due to the presence of the gas line. The undocumented fill is approximately 2- to 5-feet-thick and is
Project No. 06403-52-31 -2- March 23, 2007
considered unsuitable for support of settlement sensitive improvements. These soils are located
p beyond planned development and are not anticipated to impact the project as presently proposed.
4.3 Lindavista Formation (QIn)
The majorityof the Lindavista Formation was removed during the mass grading operation, except
within the vicinity of the existing high-pressure gas line, along the western boundary. The Lindavista
Formation generally consists of dense to very dense, silty sandstone and is considered suitable for the
support of the proposed development.
4.4 Santiago Formation (Ts)
The Eocene-age Santiago Formation, consisting of dense, massive, white to light green, silty, fine to
coarse sandstones with occasional interbeds of hard, greenish-gray to brown claystones and siltstones,
is exposed at finish grade within the western and southeastern portions of the site, and underlies the
compacted fill. The Santiago Formation is considered suitable for the support of the proposed
development.
5. GROUNDWATER
Groundwater was not encountered during grading operations of the site. It is not uncommon for
groundwater or seepage conditions to . develop where none previously existed. Groundwater
elevations are dependent on seasonal precipitation, irrigation, and land use, among other factors, and
vary as a result. Proper surface drainage of irrigation and rainwater will be important to future
performance of the project.
6. GEOLOGIC HAZARDS
6.1 Faulting and Seismicity
Based on the field investigation and review of aerial photographs, published geologic maps, and
previous geotechnical reports; the site is not located on any active or potentially active fault trace as
defined by the California Geological Survey (CGS).
The distance of known faults to the site was determined from the computer program. EQFAULT
(Blake, 2000). The program estimates ground accelerations at the site for the maximum seismic
events based upon distances from the site to known California active faults that have been digitized in
an earthquake catalog.
The results of the deterministic analysis indicate that the Rose Canyon Fault is the dominant source of
potential ground shaking at the site. The Rose Canyon Fault is estimated to have the capability to
Project No. 06403-52-31 -3 - March 23, 2007
generate a maximum earthquake event of Magnitude 7.2. The estimated maximum peak site
acceleration was calculated to be 0.32 g. Presented on Table 6.1 are the earthquake events and
calculated peak site accelerations for the faults most likely to subject the site to significant ground
shaking.
TABLE 6.1
DETERMINISTIC SITE PARAMETERS FOR SELECTED FAULTS
Fault Name Distance from Site
(miles)
Maximum
Earthquake
Maximum Site
Acceleration (g)
Rose Canyon 7 7.2 0.32
Newport-Inglewood (Offshore) 10 7.1 0.25
Coronado Banks Fault Zone 22 7.6 0.17
Elsinore-Julian 23 7.1 0.13
Elsinore-Temecula 23 6.8 0.10
Elsinore-Glen Ivy 37 6.8 0.06
Earthquake Valley 40 65 0.04
Palos Verdes 41 7.2 1 0.06
San Jacinto-Anza 46 7.2 1 0.06
It is our opinion the site could be subjected to moderate to severe ground shaking in the event of an
earthquake along any of the faults listed on Table 6.1 or other faults in the southern California/
northern Baja California region. We do not consider the site to possess a greater risk than that of the
surrounding developments. While listing peak accelerations is useful for comparison of the potential
effects of fault activity in the region, other considerations are important in seismic design, including
the frequency and duration of motion and the soil conditions underlying the site. We recommend that
seismic design of the structures be performed in accordance with the California Building Code (CBC)
guidelines and/or those currently adopted by the City of Carlsbad.
6.2' Liquefaction
Liquefaction typically occurs when a site is located in a zone with seismic activity, on-site soil is
cohesionless, groundwater is encountered within 50 feet of the surface, and soil relative densities are
less than about 70 percent. If all four previous criteria are met, a seismic event could result in a rapid-
pore water pressure increase from the earthquake-generated ground accelerations. Due to 'the
relatively dense nature of the compacted fill and formational materials and lack of permanent
groundwater table, the potential for liquefaction occurring at the site is considered to be very low.
6.3 Landslides
No landslides are known to affect the subject site.
Project No. 06403-52-31 - - -4- March 23, 2007
7. CONCLUSIONS AND RECOMMENDATIONS
7.1 General
7.1.1 No soil or geologic conditions were encountered during previous geotechnical
investigations or grading operations that, in our opinion, would preclude the continued
development of the property as presently planned, provided that the recommendations of
this report are followed.
7.1.2 The on-site geologic units have permeability characteristics and/or fracture systems that are
conducive to water transmission, natural or otherwise (e.g., landscape), and may result in
future seepage conditions. It is not uncommon for groundwater or seepage conditions to
develop where none previously existed, particularly after landscape irrigation is initiated.
The occurrence of induced groundwater seepage from landscaping can be greatly reduced
by implementing and monitoring a landscape program that limits irrigation to that
sufficient to support the vegetative cover without over watering. Shallow subdrains may be
required in the future if seeps occur after rainy periods or after landscaping is installed.
7.2 Soil and Excavation Characteristics
7.2.1 The finish-grade soils tested during the mass grading operations indicate that the prevailing
soil conditions within 3 feet of grade have an Expansion Index less than 20 and are
classified as having a very low expansion potential as defined by CBC Table 18-I-B.
Expansion Index test results are presented on Table A-I.
7.2.2 The existing compacted fill soil should generally require light to moderate effort to
excavate using conventional heavy-duty grading equipment. Excavations into Santiago
Formation (exposed at grade and underlying the compacted fill soils) will likely require
moderate to heavy ripping. In addition, concretionary lenses or layers may exist within the
Santiago Formation that may cause difficult excavation and potentially may generate
oversize material (fragments greater than 6 inches in maximum dimension).
7.3 Grading
7.3.1 Grading should be performed in accordance with the Recommended Grading Specifications
in Appendix B and the City of Carlsbad Grading Ordinance. Where the recommendations
of this report conflict with Appendix B, the recommendations of this section take
precedence.
Project No. 06403-52-31 - - 5 - March 23, 2007
7.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with
the owner or developer, grading contractor, civil engineer, and geotechnical engineer in
attendance. Special soil handling and the fine grading plans can be discussed at that time.
- 7.3.3 Site preparation should begin with the removal of all deleterious material and vegetation, if
present. The depth of removal should be such that material exposed in cut areas or soil to
be used as fill is relatively free of organic matter. Material generated during stripping.
and/or site demolition should be exported from the site.
7.3.4 Areas to receive fill should be scarified to a depth of at least 12 inches, moisture
conditioned as necessary, and compacted to at least 90 percent relative compaction prior to
placing additional fill. In areas where proposed cuts into existing fills are less than 12
inches, the resulting finish-grade soils should be scarified, moisture conditioned as
necessary, and compacted to a minimum dry density of 90 percent of the laboratory
maximum dry density. NearLsurface soils may need to be processed to greater depths
depending on the amount of drying or.wetting that has occurred within the soils since the
initial sheet-grading of the pad. The actual extent of remedial grading should be determined
in the field by the geotechnical engineer or engineering geologist. Overly wet surficial
materials will require drying and/or mixing with drier soils to facilitate proper compaction.
7.3.5 The site should then be brought to final subgrade elevations with structural fill compacted
in layers. In general, the on-site soils are suitable for re-use as fill if free from vegetation,
debris and other deleterious material. Layers of fill should be no thicker than will allow for
adequate bonding and compaction. All fill, including wall and trench backfill, the upper 12
inches of hardscape areas, and scarified ground surfaces, should be compacted to at least 90
percent of the maximum dry density generally at or above optimum moisture content, as
determined in accordance with ASTM Test Procedure D 1557-02. The project geotechnical
engineer may consider fill materials below optimum moisture content unacceptable.
7.3.6 To reduce the magnitude of potential differential settlement of the compacted fill soil, the
cut portion of cut-fill transitions beneath building structures should be over-excavated
(undercut) a minimum of three• feet and replaced with compacted low expansive
(Expansion Index less than 50) soil fill. Cut-fill transitions are comprised of compacted fill
and formational material within 3 feet of finish grade. The undercut should extend at least 5
feet horizontally outside the limits of the building footprint area:.
7.3.7 Based on a review of the site preliminary grading plans and existing underlying fill
geometry, it is anticipated that the building pads for Building A will result in a
fill/formational transition and will likely require undercutting. The need for undercutting
Project No. 06403-52-31 - 6 - March 23, 2U07
should be determined subsequent to establishing finish grades on the grading plans and/or
during the grading.
7.3.8 It is recommended that excavations be observed during grading by a representative of
Geocon Incorporated to verify that soil and geologic conditions do not differ significantly
from those anticipated.
7.3.9 Oversize material (fragments greater than 6 inches in maximum dimension), if generated,
should not be placed within 3 feet of finish grade in pad areas and 12 inches of subgrade in
driveways. Material greater than 6 inches in maximum dimension, if generated, should be
placed in deeper fill areas. Due to the absence of large areas of available fill volume, it is
unlikely that all of the oversize material could be placed as compacted fill during the
grading operation; hence, the oversize material may require exportation.
7.3.10 It is the responsibility of the contractor to ensure that all excavations and trenches are
properly shored and maintained in accordance with applicable OSHA rules and regulations
in order to maintain safety and maintain the stability of adjacent existing improvements.
7.3.11 Import fill soil, if necessary, should consist of 6 inch minus granular materials with a "low"
expansion potential (El of 50 or less) and be free of deleterious material. Geocon
Incorporated should be notified of the import soil source and should perform laboratory
testing of import soil prior to its arrival at the site to determine its suitability as fill material.
In addition, the imported soil should be certified as being free of hazardous contaminants
as well as chemical properties that could adversely impact proposed construction material.
7.4 Seismic Design
7.4.1 Table 7.4 summarizes site-specific seismic design criteria obtained from the California
Building Code (CBC). The values listed on Table 7.4 are for the Julian segment of the
Elsinore Fault (located approximately 23 miles northeast of the site), which is identified as
a Type A fault and the Rose Canyon Fault (located approximately 7 miles west/southwest
of the site), which is identified as a Type B fault.
Project No. 06403-52-31 -7- March 23, 2007
TABLE 7.4
SITE SEISMIC DESIGN CRITERIA
Parameter Value UBC Reference
Seismic Zone Factor 0.40 Table 16-I
Soil Profile S Table 16-J
Seismic Coefficient, C. 0.40 Table 16-Q
Seismic Coefficient, C 0.56 Table 16-R
Near-Source Factor, Na 1.0 Table 16-S
Near-Source Factor, N 1.0 Table 16-T
Seismic Source AIB Table 16-U
7.5 Corrosive Potential
7.5.1 Samples obtained for expansion testing were also subjected to water-soluble sulfate testing
to assess whether the soil contains high enough sulfate concentrations that could damage
normal Portland Cement concrete. Table A-il summarizes the sulfate test results. The
results of the tests indicate a negligible sulfate rating based on Table 19-A-4 of the
California Building Code (CBC). CBC guidelines should be followed in determining the
type of concrete to be used. The presence of water-soluble sulfates is not a visually
discernible characteristic; therefore, other soil samples from the site could yield different
concentrations. Additionally, over time, future landscaping activities (e.g., addition of
fertilizers and other soil nutrients) may affect the concentration.
7.5.2 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.
7.6 Subdrains
7.6.1 Due to a lack of appreciable depressions in the natural topography within the site and
proposed shallow fills (anticipated to be generally less than 3 feet thick), subdrains are not
anticipated.
7.7. Slopes
7.7.1 Based on the referenced geotechnical reports for Villages of La Costa - The Greens
development, existing fill slopes at the site (constructed at 2:1 inclinations) possess a factor
of safety greater than 1.5 against deep-seated and surficial failure.
Project No. 06403-52-31 -8- March 23. 2007
7.7.2 No significant new slopes are planned during this phase of grading.
7.7.3 All slopes should be landscaped with drought-tolerant vegetation, having variable root
depths and requiring minimal landscape irrigation. In addition, all slopes should be drained
and properly maintained to reduce erosion.
7.8 Foundation Recommendations
7.8.1 The project is suitable for the use of continuous strip footings, isolated spread footings, or
appropriate combinations thereof, provided the preceding grading recommendations are
followed.
7.8.2 Foundations for the structures should consist of continuous strip footings and/or isolated
spread footings. Continuous footings (exterior and interior) should be at least 12 inches
wide and extend at least 18 inches below lowest adjacent pad grade and be founded entirely
on either properly compacted fill or Santiago Formation. Isolated spread footings should be
at least 2 feet wide, extend at least 24 inches below the lowest adjacent pad grade, and be
founded entirely on either properly compacted fill or Santiago Formation. Minimum steel
reinforcement for continuous footings should consist of at least four No. 4 steel reinforcing
bars placed horizontally in the footings; two near the top and two near the bottom. The
project structural engineer should provide recommendations for reinforcement of isolated
spread footings. A wall/column footing dimension detail is presented on Figure 3.
7.8.3 The foundation dimensions and concrete reinforcement recommended above are based on
soil characteristics only and are not intended to be used in-lieu of those necessary to satisfy
structural loading. The project structural engineer should design actual reinforcement of the
foundations.
7.8.4 The recommended allowable bearing capacity for foundations designed as recommended
above is 2,000 pounds per square foot (psf) for foundations in properly compacted fill
material or Santiago Formation. The allowable soil bearing pressure may be increased by
an additional 500 psf and 300 psf for each additional foot of depth and width, respectively,
to a maximum allowable bearing capacity of 4,000 psf. The values presented above are for
dead plus live loads and may be increased by one-third when considering transient loads
due to wind or seismic forces.
7.8.5 The use of isolated footings, which are located beyond the perimeter of the building and
support structural elements connected to the building, are not recommended. Where this
Project No. 06403-52-31 - 9 - March 23, 2007
condition cannot be avoided, the isolated footings should be connected to the building
foundation system with grade beams.
7.8.6 Total and differential settlements under the imposed allowable loads are estimated to be 1/2
inch.
7.8.7 No special subgrade presaturation is deemed necessary prior to placing concrete, however,
the exposed foundation and slab subgrade soils should be moistened as necessary to
maintain a moist soil condition as would be expected in any such concrete placement.
7.8.8 Foundation excavations should be observed by the Geotechnical Engineer (a representative
of Geocon Incorporated) prior to the placement of reinforcing steel and concrete to check
that the exposed soil conditions are consistent with those expected and have been extended
to appropriate bearing strata. If unexpected soil conditions are encountered, foundation
modifications may be required.
7.9. Concrete Slabs-on-Grade Recommendations
7.9..1 Concrete slabs-on-grade not subjected to vehicular traffic should be at least 5 inches thick.
Minimum slab reinforcement should consist of No. 3 steel reinforcing bars placed
18 inches on center in both horizontal directions and positioned near the slab midpoint. The
concrete slabs-on-grade should be underlain by at least 3 inches of clean sand (Sand
Equivalent greater than 30) and, where moisture-sensitive floor coverings are planned or
used to store moisture sensitive materials should be underlain by a vapor inhibitor covered
with at least 2 inches of clean sand. Where floor slabs will be subject to concentrated
loading, such as heavy stacked warehouse shelving, the slab thickness should be increased
to accommodate anticipated loading and be designed by the project structural engineer.
7.9.2 Exterior concrete flatwork not subject to vehicular traffic should be constructed in
accordance with the following recommendations. Slab panels should be a minimum of
4 inches thick and when in excess of 8 feet square should be reinforced with
6 x 6 - W2.9/W2.9 (6 x 6 - 6/6) welded wire mesh to reduce the potential for cracking. In
addition, all concrete flatwork should be provided with crack control joints to reduce and/or
control shrinkage cracking. Crack control spacing should be determined by the project
structural engineer based on the slab thickness and intended usage. Criteria of the
American Concrete Institute (AC!) should be taken into -consideration when establishing
crack control spacing. Subgrade soils for exterior slabs not subjected to vehicle' loads
should be compacted in accordance with criteria presented in the grading section prior to
concrete placement.
Project No. 06403-52-31 - _10- March 23, 2007
7.9.3 Where exterior flatwork abuts the structure at entrant or exit points, the exterior slab should
be dowelled into the structure's foundation stemwall. This recommendation is intended to
reduce the potential for differential elevations that could result from differential settlement
or minor heave of the flatwork. Dowelling details should be designed by the project
structural engineer.
7.9.4 The recommendations presented herein are intended to reduce the potential for cracking of
slabs and foundations as a result of differential movement. However, even with the
incorporation of the recommendations presented herein, foundations and slabs-on-grade
will still exhibit some cracking. The occurrence of concrete shrinkage cracks is
independent of the soil supporting characteristics. Their occurrence may be reduced and/or
controlled by limiting the slump of the concrete, the use of crack control joints and proper
concrete placement and curing. Crack control joints should be spaced at intervals no greater
than 12 feet. Literature provided by the Portland Concrete Association (PCA) and
American Concrete Institute (AC!) present recommendations for proper concrete mix,
construction, and curing practices, and should be incorporated into project construction.
7.10 Retaining Walls and Lateral Loads
7.10.1 Retaining walls 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
35 pounds per cubic foot (pcf). Where the backfill will be inclined at no steeper than 2 to 1
(horizontal:vertical), an active soil pressure of 50 pcf is recommended, pressures assume
that 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. Where
backfill materials do not conform to the above criteria, Geocon Incorporated should be
consulted for additional recommendations.
7.10.2 Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equals
the height of the retaining wall portion of the wall in feet) at the top of the wall. Where
walls are restrained from movement at the top, an additional uniform pressure of 7H psf
should be added to the above active soil pressure. For retaining walls subjected to vehicular
loads within a horizontal distance equal to two-thirds of the wall height, a surcharge
equivalent to 2 feet of soil (250 psf) should be added.
7.10.3 All retaining walls should be provided with a drainage system adequate to prevent the
buildup of hydrostatic forces and should be waterproofed as required by the project
architect. The use of drainage openings through the base of the wall (weep holes, etc.) is
not recommended where the seepage could be a nuisance or otherwise adversely impact the
property adjacent to the base of the wall. A typical retaining wall drainage system is
Project No. 06403-52-31 - 11 -- March 23, 2007
presented on Figure 4. The above recommendations assume a properly compacted granular
(Expansion Index less than 50) backfill material with no hydrostatic forces or imposed
surcharge load. If conditions different than those described are anticipated, or if specific•
drainage details are desired, Geocon Incorporated should be contacted for additional
recommendations.
7.10.4 In general, 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 than 3:1 could impact the allowable soil bearing
pressure. Therefore, Geocon Incorporated should be consulted where such a condition is
anticipated.
7.10.5 For resistance to lateral loads, an allowable passive earth pressure equivalent to a fluid
density of 300 pcf is recommended for footings or shear keys poured neat against properly
compacted granular fill soil or undisturbed natural soil. The allowable passive pressure
assumes a horizontal surface extending at least 5 feet or three times the surface generating
the passive pressure, whichever is greater. The upper 12 inches of material not protected by
floor slabs or pavement should not be included in the design for lateral resistance. An
allowable friction coefficient of 0.4 may be used for resistance to sliding between soil and
concrete. This friction coefficient may be combined with the allowable passive earth
pressure when determining resistance to lateral loads.
7.106 The recommendations presented above are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 8 feet. In the event that
walls higher than 8 feet or other types of walls (such as crib-type walls) are planned,
Geocon Incorporated should be consulted for additional recommendations.
7.11 Preliminary Flexible Pavement Recommendations
7.11.1 Preliminary pavement recommendations provided are based on our experience with similar
soil conditions. For driveways and parking areas, design and construction criteria should
conform to City of Carlsbad standards. We assume the pavement surface will have
automobile and light-duty truck traffic. We have also assumed an R-value of 15 for the
proposed subgrade soils. The following preliminary pavement recommendation is for
planning and estimating purposes only, and not for construction.
Project No. 06403-52.31 -12- March 23, 2007
TABLE 7.11
PRELIMINARY PAVEMENT SECTION
Location Assumed Assumed Asphalt Concrete Aggregate Base
Traffic Index R-Value (inches) Material (inches)
Driveways and 5.0 15 4 6 Parking Areas
7.11.2 The following recommendations should also be implemented:
The upper 12 inches of the subgrade supporting the structural section should be
scarified, moisture conditioned, and compacted to a dry density of at least 95
percent of the laboratory maximum dry density near to slight over optimum
moisture as determined by ASTM Test Method D 1557-02. The upper 12 inches of
subgrade supporting hardscape areas should be processed and compacted per
recommendations provided in Section 7.3.5.
Aggregate base material should be properly moisture conditioned and compacted
to a dry density at least 95 percent of the laboratory maximum dry density at near
to slightly above optimum moisture content per ASTM D 1557-02.
Asphalt concrete should be compacted to at least 95 percent of the Hveem density
as determined by ASTM D 2726-05A.
Asphalt concrete should conform to Section 203-6 of the Standard Specifications
for Public Works Construction (Greenbook). Aggregate base (Class II) materials
should conform to Section 26-1.02A of the Standard Specifications of the State of
California, Department of Transportation (Caltrans) or approved equivalent.
Additionally, all materials should conform to City of Carlsbad specifications.
7.112 Slope Maintenance
7.12.1 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 3 feet of a portion 'of the slope and usually
does not directly' impact the improvements on the pad areas above or below the slope. The
occurrence of surficial instability is more prevalent on fill slopes and is generally preceded
by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage.
The disturbance and/or loosening of the surficial soil, as might result from root growth, soil
expansion, or excavation for irrigation lines and slope planting, may also be a significant
contributing factor to surficial instability. It is therefore recommended that, to the
maximum extent practical: (a) disturbed/loosened surficial soil be either removed or
properly recompacted; (b) irrigation systems be periodically inspected and maintained to
eliminate leaks and excessive irrigation; and (c) surface drains on and adjacent to slopes be
Project No. 06403-52-31 -13- March 23. 2007
periodically maintained to preclude ponding or erosion. 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.
7.13 Site Drainage
7.13.1 Adequate drainage is critical to reduce the potential for differential soil movement, erosion,
and subsurface seepage. Under no circumstances should water be allowed to pond adjacent
to footings or behind retaining walls. The site should be graded and maintained such that
surface drainage is directed away from structures and the top of slopes into swales or other
controlled drainage devices. Roof and pavement drainage should be directed into conduits
that carry runoff away from the proposed structure.
7.13.2 All underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks for early detection of water infiltration and detected leaks should be
repaired promptly. Detrimental soil movement could occur if water is allowed to infiltrate
the soil for a prolonged period of time.-
7.13.3 Landscaping planters adjacent to paved areas are not recommended due to the potential for
surface or irrigation water to infiltrate the pavement's subgrade and base course. We
recommend that drains to collect excess irrigation water and transmit it to drainage
structures or impervious above-grade planter boxes be used. In addition, where landscaping
is planned adjacent to the pavement, we recommend construction of a cutoff wall along the
edge of the pavement that extends at least 6 inches below the bottom of the base material.
Project No. 06403-52-31 - - -14- March 23, 2007
LIMITATIONS AND UNIFORMITY OF CONDITIONS
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 pan of the scope of
services provided by Geocon Incorporated.
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 that the necessary steps are taken to see that the contractor and subcontractors
carry out such recommendations in the field.
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 are 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. 06403-52-31 March 20, 2007
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SOURCE: 2006 THOMAS BROS. MAP
SAN DIEGO COUNTY, CALIFORNIA
REPRODUCED WITH PERMISSION GRANTED BY THOMAS BROS. MAPS.
THIS MAP IS COPYRIGHT BY THOMAS BROS. MAPS. IT IS UNLAWFUL TO COPY
OR REPRODUCE ALL OR ANY PART THEREOF, WHETHER FOR PERSONAL USE OR
RESALE, WITHOUT PERMISSION.
GE000N 400 INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
PHONE 853 558-6900 - FAX 858 558-6159
AS/AML DSKIE0000
GEOTEG/PSATEJGJ,4PDWG/
I N
NO SCALE
VICINITY MAP
VILLAGES OF LA COSTA -. THE GREENS
NEIGHBORHOOD 1.01 ECR CORPORATE CENTER
CARLSBAD, CALIFORNIA
DATE 03-23-2007. 1 PROJECT NO. 06403 - 52 - 31 1 HG. 1
WALL FOOTING
CONCRETE SLAB
I... -. ••4. - . t . .............:
A
SAND ;• PAD GRADE
-...J n C9 VISQUEEN
00 00 LL LL.
I L
' WIDTH
COLUMN FOOTING
CONCRETE SLAB
...., .:::.':
44 1 . 4.'
SAND
VISQUEEN_-J
-.Z___________ .
a '
• /
D Lu
FOOTING WIDTH*
*SEE REPORT FOR FOUNDATION WITDH AND DEPTH RECOMMENDATION
I WALL/ COLUMN FOOTING DIMENSION DETAIL I
N GE000N
INCORPORATED low
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA92121-2974
PHONE 858 558-6900 - FAX 858 558-6159
FKIAML bsK/E0000
couooTzcwG,.,
VILLAGES OF IA COSTA - THE GREENS
NEIGHBORHOOD 1.01 ECR CORPORATE CENTER
CARLSBAD, CALIFORNIA
I DATE 03-23-2007 I PROJECT NO. 06403 - 52 - 31 I FIG. 3
RETAINING WALL
GROUND
17 MIN. SURFACE
U
-3I4 CRUSHED I GRAVEL
H MIRAF1 140N 4--- FILTER FABRIC
OR EQUIVALENT
4 DIA. PERFORATED r SCHEDULE 40 PVC PIPE
NOTES:
I......PREFABRICATED DRAINAGE PANELS SUCH AS MIRADRAIN 6000 OR EQUIVALENT
MAY BE USED IN LIEU OF PLACING GRAVEL
2......DRAIN SHOULD BE UNIFORMLY SLOPED AND MUST LEAD TO A POSITIVE GRAVITY
OUTLET OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING.
WALL DRAINAGE DETAIL
NO SCALE
VILLAGES OF LA COSTA - THE GREENS
NEIGHBORHOOD 1.01 ECR CORPORATE CENTER
CARLSBAD, CALIFORNIA
DATE 03-23-2007. 1 PROJECT NO. 06403 - 52 - 31 74
WAL4NC
APPENDIX A
LABORATORY RESULTS
FOR
VILLAGES OF LA COSTA -
THE GREENS
NEIGHBORHOOD 1.01
ECR CORPORATE CENTER L.P.
CARLSBAD, CALIFORNIA
PROJECT NO. 06403-52-31
TABLE A-I
SUMMARY OF FINISH GRADE EXPANSION INDEX TEST RESULTS
VILLAGES OF LA COSTA, THE GREENS - NEIGHBORHOOD 1.02
Sample at Finish Grade Expansion Index USC Classification
El-A 19 Very Low
El- C 1 Very Low
TABLE A-Il
SUMMARY OF WATER-SOLUBLE SULFATE LABORATORY TEST RESULTS
CALIFORNIA TEST 417
Water-Soluble Sulfate Sulfate Exposure
Sample No. (%) USC Table 19-A-4
El-A 0.047 Negligible
El-C 0.045 Negligible
I'
P
Project No. 06403-52-31 - March 23, 2007
APPENDIX
APPENDIX B
RECOMMENDED GRADING SPECIFICATIONS
FOR
VILLAGES OF LA COSTA -
THE GREENS; NEIGHBORHOOD 1.01,'
ECR CORPORATE CENTER
CARLSBAD, CALIFORNIA
PROJECT NO. 06403-52-31
RECOMMENDED GRADING SPECIFICATIONS
p 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
recommendations 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. The Consultant should provide adequate testing and observation services so
that they may assess whether, in their 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 them 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, 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 grading 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. 10/06
2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm
I 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 Contracto?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
I
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 % 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 filb 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 34 inch in maximum dimension. The quantity of fines shall be
less than approximately 20 percent of the rock fill quantity.
GI rev. 10/06
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 Samples of soil materials to be used for fill should 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 /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.
'I
GI rev. 10/06
4.2 Any asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility. Concrete fragments that 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 and other unsuitable material, loose or
porous soils shall be removed to the depth recommended in the Geotechnical Report. The
depth of removal and compaction should 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 5:1 (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
FinishGrade Ground
2
Finish Slope Surface
Remove All -
Unsuitable Material
As Recommended By
Consultant Slope To Be Such That
Sloughing Or Sliding
Does Not Occur
See Note 1 See Note2
No Scale
DETAIL NOTES: Key width "B" should be a minimum of 10 feet, 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.
The outside of the key should be below the topsoil or unsuitable surflcial
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. 10/06
II
4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture
conditioned to achieve the proper moisture content, and compacted as recommended in
Section 6 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 D 1557-02.
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. 10/06
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.
P 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 D 1557-02. Compaction shall be continuous
over the entire area,and compaciin equipment shall make sufficient passes so that
the specified minimum relative compaction has been achieved throughout the
entire fill.
6.1.6 Where practical, soils having an Expansion Index greater than 50 should be 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. 10/06
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 Rock placement, fill placement and flooding of approved granular soil in the
windrows should be continuously observed by the Consultant.
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). 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. 10/06
required compaction or deflection as recommended in Paragraph 6.3.3 shall be
utilized. The number of passes to be made should 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 D 1196-93, may be performed in
both the compacted soil fill and in the rock fill to aid in determining the required
minimum number of passes of the compaction equipment. If performed, a
minimum of three plate bearing tests should 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 should be present during rock fill operations to
observe 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.
6.3.5 Test pits shall be excavated by the Contractor so that the Consultant can state that,
in their 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.
6.3.7 Rock fill placement should be continuously observed during placement by the
Consultant.
GI rev. 10/06
7. OBSERVATION AND TESTING.
7.1 The Consultant shall, be the Owner's 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 should be placed without at least one field density
test being performed within that interval. In addition, a minimum of one field density test
should be performed for every 2,000 cubic yards of soil or soil-rock fill placed and
compacted.
7.2 Thç Consultant should perform a sufficient distribution of field density tests of the
compacted soil or soil-rock fill to provide a basis for expressing an opinion 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 should observe that the minimum number of
passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant
should 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. When observations 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.
7.5 The Consultant should 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:
GI rev. 10/06
I
7.6.1 Soil and Soil-Rock Fills:
P 7.6.1.1 Field Density Test, ASTM D 1556-02, Density of Soil In-Place By the
Sand-Cone Method.
7.6.1.2 Field Density Test, Nuclear Method, ASTM D 2922-01, Density of Soil
and Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
7.6.1.3 Laboratory Compaction Test, ASTM D 1557-02, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound
Hammer and 18-Inch Drop.
7.6.1.4. Expansion Index Test, ASTM D 4829-03, Expansion Index Test.
7.6.2 Rock Fills
7.6.2.1 Field Plate Bearing Test, ASTM D 1196-93 (Reapproved 1997)
Standard Method for Nonreparative 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. 10/06
9. CERTIFICATIONS AND FINAL REPORTS
p
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.
0! rev. 10/06
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