HomeMy WebLinkAbout34165-01 Preliminary Geotechnical Investigation AA GWA 5-5-20 DL
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May 5, 2020 File No. 34165-01
Julie Laughton Design Build 28885 Woodspring Circle
Trabuco Canyon, CA 92679 Attention: Ms. Julie Laughton Subject: PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed residential development 1616 West Oceanfront Newport Beach, California Dear Ms. Laughton:
In accordance with your request, American Geotechnical performed a geotechnical investigation of the subject site. The purpose for the investigation was to evaluate the geotechnical conditions at the site and provide soil design parameters and earthwork recommendations for the project. This report is prepared in
general conformance with our proposal dated December 5, 2019, and your written authorization.
The results of the investigation indicate that the proposed development is feasible provided the
recommendations contained herein are incorporated into the project plans and specifications. This report should be reviewed in detail by all parties involved with the construction prior to proceeding further with the planned development and should be considered part of the construction documents. Should you have any
questions regarding the information contained herein, please do not hesitate to contact our office. When formal plans become available, they should be forwarded to our office for review and comment before being submitted to the permitting authority.
We appreciate the opportunity to be of service. Should you have any questions regarding the information contained in this report, please do not hesitate to contact us.
Sincerely, AMERICAN GEOTECHNICAL, INC.
Arumugam Alvappillai, Ph.D. Gregory W. Axten Principal Engineer Principal Engineer/CEO
G.E. 2504 G.E. 103 Enclosures: Appendix A – Boring Logs
Appendix B – Summary of Laboratory Data Appendix C – Liquefaction Analysis Appendix D – Geotechnical Guidelines for Grading Projects Distribution: Addressee (Email: Julie@julielaughton.com)
wpdata/OC/34165-01 – Preliminary Geotechnical Investigation – AA GWA 5-5-20 DL
File No. 34165-01 May 5, 2020 Page 2
1.0 INTRODUCTION
1.1 PURPOSE
The purpose of this investigation was to evaluate the site geotechnical conditions and to provide geotechnical
recommendations for design and construction of the proposed development.
1.2 SCOPE OF SERVICES
The scope of the work performed during this investigation involved the following:
• Research and review of available pertinent geotechnical literature.
• Site reconnaissance to observe general site conditions.
• Subsurface exploration consisting of drilling two (2) small-diameter borings, AGSB-1 and AGSB-2,
in the area of the proposed construction.
• Sampling and logging of the subsurface soil.
• Laboratory testing of select soil samples collected from the exploratory boring to determine the
engineering properties of the soil.
• Engineering and geologic analyses of the field and laboratory data.
• Preparation of this report summarizing our findings, conclusions, and recommendations for the
proposed construction.
1.3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION
The site is located within the Balboa Peninsula of the City of Newport Beach. The property is relatively flat, a
roughly rectangular lot, and is presently occupied with a two- story residential structure and the associated
appurtenant improvements. The property is bounded by West Oceanfront in the north, beach front in the
south, and similar residential properties to the east and west. A City owned asphalt paved walkway exists in
the south portion of the property. A site location map is shown in Plate 1 and an aerial view is presented in
Plate 2.
As we understand, the proposed construction includes demolishing all existing improvements including the
structure and constructing a new three-level residential building. The new building will be constructed at an
approximately same lot elevation of the existing building and will incorporate a pickleball ball court and a pool
in the lower and roof levels of the structure, respectively. It is our understanding that data obtained from this
investigation will be used in the development of grading and foundation plans. When grading and foundation
File No. 34165-01 May 5, 2020 Page 3
plans for the specific type(s) of construction become available, the plans must be submitted to this office for
review and comment. The recommendations provided herein may be revised upon our review of the
grading/construction plan(s) and further site analyses.
2.0 INVESTIGATION
2.1 FIELD EXPLORATION
A subsurface investigation was performed at the subject site on February 27, 2020 and
March 11, 2020, and consisted of drilling two (2) small-diameter hollow-stem auger borings, AGSB-1and
AGSB-2. AGSB-1 was drilled in the north side of the property under the covered carport using a tri-pod drilling
equipment. The boring AGSB-2 was drilled in the south side patio area using limited access drilling rig. The
purpose of the exploratory borings was to determine the existing subsurface conditions and to collect
subsurface data in areas of anticipated new construction.
The borings were drilled to a maximum depth of 50 feet below the existing ground surface. The materials
encountered within all our borings consisted of poorly graded beach sand. Groundwater was encountered at
6.5 to 7 feet from the ground surface in both borings. The exploratory borings were logged by field personnel
using both visual and tactile means. Bulk and relatively undisturbed drive samples, considered representative
of subsurface material, were collected and forwarded to the laboratory for testing. Drive samples from the
exploratory borings were obtained with:
1. A 2.5-inch inside diameter (3.0-inch outside diameter) split barrel, thin-wall sampler equipped with brass
liner rings.
2. A standard split-spoon sampler with dimensions in accordance with ASTM D1586.
Both samplers were driven with a 140-pound weight falling 30 inches. The blow counts to drive the thin-wall
sampler were corrected and the equivalent Standard Penetration Test ("N") values are indicated on the boring
logs. The Standard Penetration Test values were obtained with the standard split-spoon sampler and are also
shown on the logs.
The approximate location of the borings is shown on Plate 2. The logs of the exploratory borings are
presented in Appendix A.
File No. 34165-01 May 5, 2020 Page 4
2.2 LABORATORY TESTING
Laboratory testing was performed on representative samples obtained during our field exploration. Samples
were tested for the purpose of estimating material properties for use in subsequent engineering evaluations.
Testing included in-situ moisture and density, gradation, chemical soil testing, and strength testing. A
summary of laboratory test results is included in Appendix B.
3.0 GEOLOGY AND SEISMICITY
3.1 GEOLOGY
The site is located on the Balboa Peninsula behind the modern beach strand of Newport Beach. The elevation
at the site is about 10 feet above mean sea level. The site is underlain by unconsolidated, beach sand and
eolian sand of latest Holocene age. Geotechnical characteristics of earth materials encountered in subsurface
exploration completed on site are described in previous sections of this report.
Groundwater
Groundwater was encountered in the exploratory borings at a depth of 6.5 to 7 feet below the ground surface.
The groundwater table appears to be roughly coincident with sea level.
Landslides
No known landslides are mapped on or adjacent to the site based on regional geologic maps. The site is not
located in a State of California Seismic Hazard Zone for Earthquake Induced landslides.
3.2 SEISMICITY
A risk common to all areas of southern California that should not be overlooked is the potential for damage
resulting from seismic events. There are no known faults cross or project into the site based on regional
geologic maps; however, the site is located within the surface expression of the Newport-Inglewood Fault
Zone. The site is not located in a State of California Earthquake Fault Hazard Zone. The active portion of the
fault is located about 3 miles northwest of the site.
3.2.1 Fault Rupture
Surface rupture occurs when movement on a fault breaks through to the surface. The rupture almost always
follows preexisting faults, which are zones of weakness, and may occur suddenly during an earthquake or
File No. 34165-01 May 5, 2020 Page 5
slowly in the form of fault creep. Sudden displacements are more damaging to structures because they are
accompanied by shaking.
The project area is not located within an Alquist-Priolo Earthquake Fault Zone, and no active faults are mapped
to pass through the project site. Therefore, the risk of ground surface fault rupture at the project site is low.
3.2.2 Ground Shaking
The intensity of the seismic shaking or strong ground motion at the project site during an earthquake depends
on the distance between the project area and the epicenter of the earthquake, the magnitude of the
earthquake, and the geologic conditions underlying and surrounding the site. Earthquakes occurring on faults
closest to the project site would most likely generate the largest ground motions within the project area.
Seismic design parameters regarding the ground shaking are presented in Section 4.3.
3.2.3 Liquefaction and Seismic Settlement
The site is located within an area identified as having a potential liquefaction hazard. Liquefaction is a
phenomenon in which saturated granular sediments temporarily lose their shear strength during periods of
earthquake-induced strong ground shaking. The susceptibility of a site to liquefaction is a function of the
depth, density, and water content of the sediments and the magnitude of an earthquake. Saturated,
unconsolidated silts, sands, silty sands, and gravels within 50 feet of the ground surface are most susceptible
to liquefaction. Typical effects of liquefaction include loss of bearing strength, lateral spreading, and
settlement.
In order to determine the liquefaction potential at the site, a site-specific liquefaction analysis was performed
using the computer program LiquefyPro and the subsurface data collected in our boring AGSB-2. Using the
USGS Earthquake Hazard Tool as well as site specific ground motion procedures outlined in the code, a
design earthquake magnitude of 6.7 and site peak ground acceleration (PGAM) of 0.718g were selected for our
analysis. A depth to groundwater of 5 feet was used. The results of our liquefaction analyses (see Appendix
C) indicate that most of the soil layers under the groundwater are potentially liquefiable. Our analyses also
predicted about 0.4 inch of liquefaction settlement during the design seismic event. The potential differential
settlement from liquefaction is approximately half of the total settlement (i.e., about 0.2 inches).
File No. 34165-01 May 5, 2020 Page 6
3.2.4 Tsunami
The site is in a California Geological Survey Tsunami Inundation Zone.
4.0 CONCLUSIONS & RECOMMENDATIONS
4.1 BASIS
Conclusions and recommendations contained in this report are based upon information provided, information
gathered, laboratory testing, engineering and geologic evaluations, experience, and judgment.
Recommendations contained herein should be considered minimums consistent with industry practice. More
rigorous criteria could be adopted if a lower risk of future problems is desired. Where alternatives are presented,
regardless of what approach is taken, some risk will remain, as is always the case. Usually the lowest risk is
associated with the greatest cost.
4.2 SITE SUITABILITY
Geotechnical exploration, analyses, experience, and judgment result in the conclusion that the proposed
development is geotechnically feasible. It is our opinion that the site can be improved without hazard of
landslide, slippage, or damaging settlement, and improvement can occur without similar adverse impact on
adjoining properties. Realizing this expectation will require adherence to good construction practice, agency
and code requirements, the recommendations in this report, and possible addendum recommendations made
after plan review and at the time of construction.
4.3 SEISMIC DESIGN CONSIDERATION
4.3.1 CBC Design Parameters
Based on the available information about the fault zone closet to the site and the soil conditions, the following
seismic design parameters are recommended according to the 2019 Edition of the California Building Code
(CBC)/ ASCE 7-16. Final selection of the appropriate seismic design coefficients should be made by the
structural consultant based on the local laws and ordinances, expected response of the proposed structure and
desired level of conservatism.
File No. 34165-01 May 5, 2020 Page 7
TABLE 1
Seismic Hazard Response Parameters and Design Parameters
Latitude: 33.607° - Longitude: -117.923°
Seismic Parameter Symbol Value
Site Class - F
Risk Category - II
Spectral response acceleration parameter at short periods adjusted for site
class effects SMS 1.827g
Spectral response acceleration parameter at a period of 1 s adjusted for site
class effects SM1 1.108g
Design spectral response acceleration parameter at short periods SDS 1.218g
Design spectral response acceleration parameter at a period of 1 s SD1 0.739g
Peak Ground Acceleration adjusted for site class effects PGAM 0.718g
Notes: 1. The site is located within a liquefaction zone and as such a site Class of F should be used in the design. 2. The above design parameters are determined based on site class D and using Southern California Earthquake Center (SCEC) UGMS MCER Tool. Per ASCE 7-16, Section 20.3, site class D can be utilized for structures that have fundamental periods of vibration equal to or less than 0.5s. If the fundamental period is more than 0.5s, above parameters should not be used and a site response analysis should be performed.
It should be realized that the purpose of the seismic design utilizing the above parameters is to safeguard against
major structural failures and loss of life, but not to prevent damage altogether. Even if the structural engineer
provides designs in accordance with the applicable codes for seismic design, the possibility of damage cannot be
ruled out if moderate to strong shaking occurs as a result of a large earthquake. This is the case for essentially
all structures in Southern California.
4.3.2 Liquefaction Potential
As discussed before, the site is located within a liquefaction zone. A total and differential liquefaction
settlement of approximately 0.4 and 0.2 inches, respectively are predicted based on a design earthquake
magnitude of 6.7 and site peak ground acceleration (PGAM) of 0.718g. A groundwater depth of 5 feet below
ground surface was assumed in the analysis under these conditions. Since the predicated liquefaction
settlement is not very significant, no special mitigation methods are recommended.
File No. 34165-01 May 5, 2020 Page 8
4.4 Grading
General
Grading is required for the proposed construction. When grading is conducted, it should be done in
accordance with good construction practices, minimum code requirements, and the recommendations to
follow. General guidelines for grading projects are also provided in Appendix D.
Site Preparation and Grading
Prior to the start of grading operations, utility lines within the project area, if any, should be located and marked
in the field so they can be rerouted or protected during site development. All concrete, debris and perishable
material within the area of construction should be removed from the site. The concrete foundation for the
existing building should be entirely removed from the site.
Based on the information obtained from our investigation, a minimum over-excavation of 4 feet is
recommended throughout the pad area for the proposed building addition. The actual removal depth may be
locally increased based on the soil conditions encountered during grading. The over-excavation should also
provide for a minimum of 2 feet of a properly compacted fill blanket below the bottom of the foundation system.
In areas where less critical improvements such as walkways and pavements are planned, minimum depth of
over-excavation and re-compaction is 2 feet.
Based on our exploration at the site, the material present on-site can be easily excavated with conventional
construction equipment. A representative of the geotechnical engineer should be present to review all
excavations prior to placing fill. Except at fixed boundary conditions, such as the property boundaries, the
limits of remedial grading should extend a minimum of 5 feet beyond the footprint of the proposed
improvements. In the area where the construction abuts the property line walls or existing buildings, it is
recommended that a temporary 1.5:1 (horizontal to vertical) backcut be made to help mitigate potential
damage to existing structure. When excavations deeper than 4 feet are made, the contractor should provide
temporary construction slopes and/or shoring as necessary. Temporary construction slopes should be no
steeper than 1.5:1 (horizontal to vertical). It should be realized that the site is underlain by sand that are
subjected to sloughing and caving. Sheeting and bracing should be provided by the contractor, as necessary,
to protect workers in the excavation.
File No. 34165-01 May 5, 2020 Page 9
Where excavations undermine existing improvements, such as the existing walls, etc., temporary structural
support should be provided to reduce the risk of damage resulting from undercutting. Even though not
anticipated at this time, any permanent cut and fill slopes should not be constructed steeper than 2:1, and
should be considered subject to review by the geotechnical consultant at the time of grading. These slopes
should possess sufficient compacted fines to limit erosion risk. If upon construction, relatively clean,
cohesionless sands are encountered, reconstruction by blending in fines to compacted fill and/or flattening of
slopes will be advised.
Where fill is to be placed, the upper 6 to 8 inches of the surface exposed by the excavation should be scarified,
moisture-conditioned to 2 to 3 percent over optimum moisture content, and compacted to 90 percent relative
compaction.1 If localized areas of relatively loose soil prevent proper compaction, over-excavation and re-
compaction will be necessary. The on-site soil is generally suitable for use as compacted fill and backfill,
provided that any cobbles or rock fragments greater than 4 inches are screened and removed from the soil prior
to placement and compaction. A limitation of particle size to 2 inches is preferred.
All grading should be conducted in accordance with the applicable codes, agency requirements, the
aforementioned recommendations, and the grading guidelines that accompany this report as mentioned above.
Import Fill Material
The import fill material, if utilized, should meet the following criteria:
1. No particles larger than 4 inches in largest dimension (limit to 2 inches is preferred).
2. Free of perishable material.
3. Plasticity Index of 20 or less and Liquid Limit of 40 or less.
4. Expansion Index of 20 or less.
4.5 Preliminary Foundation Recommendations
General
Minimum criteria for the design of foundations applicable to the project are provided below. The criteria should
not be considered a substitute for design by a structural engineer. The structural engineer should analyze the
1 Relative compaction refers to the ratio of the in-place dry density of soil to the maximum dry density of the same material as obtained by the "modified proctor" (ASTM D1557) test procedure.
File No. 34165-01 May 5, 2020 Page 10
actual soil-structure interaction and consider, as needed, bearing, strength, stiffness, and deflections in the
various slab, foundation, and other elements of the proposed structure to develop appropriate, design-specific
details. Other influences may have to be considered as conditions dictate. The structural engineer should
consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer
result in less critical details than are provided herein as minimums, the minimums presented herein should be
adopted. It is likely that some more restrictive details will be required. If the structural engineer has any
questions or requires further assistance, please do not hesitate to call or otherwise transmit the engineer's
requests.
Foundation Design
The proposed building addition can be supported on a conventional shallow foundation system on compacted
fill. A minimum 2 feet of compacted fill blanket below the bottom of the footing is recommended. Allowable
design parameters for foundations are provided below.
Minimum exterior and interior footings embedment into compacted fill
(measured from lowest adjacent grade) ....................................................... 24 inches Minimum footing width .................................................................................. 18 inches Allowable Bearing pressure
a. Sustained loads (pounds per square foot) .............................................. 2,000 psf b. Total loads (including wind or seismic, increase by one-third)................. 3,000 psf Resistance to lateral loads
a. Passive soil resistance (pounds per cubic foot) within compacted fill .................................................................................. 200 pcf b. Coefficient of sliding friction ............................................................................ 0.45
Subgrade Plate Test Modulus .......................................................................... 100 pci Subgrade Wide Area Modulus ............................................................................ 60 pci The allowable bearing pressures are for dead plus long-term live loads and include a factor-of-safety of at least
3.0. The allowable bearing pressure indicated above can be increased by 500 psf for every additional foot of
embedment, but not to exceed 3,000 psf. It should be noted that a minimum 2 feet of uniform fill blanket below
File No. 34165-01 May 5, 2020 Page 11
the footing bottom is recommended above. As such, if the footing depth is increased, the minimum depth of
removal and recompaction should also be increased accordingly.
Footings can be designed to resist lateral loads by using a combination of sliding friction and passive
resistance. The coefficient of friction should be applied to dead load forces only. The upper 1-foot of passive
resistance should be neglected where the soil is not confined by slabs or pavements.
Footings designed and constructed in accordance with the foregoing criteria are expected to settle less than 1-
inch. Differential settlement of approximately half of the total settlement is expected over a distance of about
50 feet.
Building Slab-on-Grade
The slab-on-grade in the interior of the addition should be a minimum of 6 inches thick and reinforced with
No. 4 bars at 12 inches on center, both ways. The structural engineer should provide final slab detailing as
necessary based on the overall foundation design. The slab should be underlain by 15-mil Stego wrap
membrane. The Stego membrane splices should be staggered between layers. The membrane should be
sealed at all splices, around plumbing, and at the perimeter of slab areas. Every effort should be made to
provide a continuous barrier and care should be taken not to puncture the membrane. Below the membrane and
on top of the subgrade, an approximately 4-inch thick layer of free-draining crushed rock base (e.g., 3/4-inch
rock) is suggested. The crushed rock should have no more than 10 percent passing the 3/4-inch sieve or more
than 3 percent passing the No. 200 sieve. To protect the Stego membrane from the angular corners of crushed
rock, a layer of Mirafi 140N should be placed on the rock subgrade with 8-inch laps at splices.
4.6 Retaining Walls
Wherever retaining walls are planned, they should be designed to resist an equivalent fluid pressure of 45
pounds per cubic foot (pcf) for level backfill. Appropriate allowances should be made for anticipated surcharge
loading. It is assumed that the project engineer will incorporate an appropriately designed wall backdrain
system for the purpose of mitigating potential for hydrostatic and/or seepage forces. It is also assumed that a
predominantly granular, non-expansive backfill is provided. The minimum widths recommended for granular
backfill are 1.5 feet at the base of the wall and 0.6 times that height of the wall at the top. The uppermost 1.0
to 1.5 feet preferably should be backfilled with more cohesive material to minimize surface infiltration.
File No. 34165-01 May 5, 2020 Page 12
If walls are restrained against free movement by structural detailing, the active values given above should be
increased. Although actual increase depends on the degree of restraint, 50 percent is recommended for
design purposes. Walls designed without this restraint-related surcharge should anticipate wall rotation
between about 0.002 to 0.01H.
For walls with retaining height of more than 6 feet, seismic earth pressure should be added to the static earth
pressures given above. The recommended seismic earth pressure for the site is 28 pcf. For simplicity, the
seismic earth pressure can be applied as a uniform pressure equal to 14 times H, where H is the retained
height.
It should be pointed out that the use of heavy compaction equipment in close proximity to the retaining walls
can result in excess wall movement and/or soil loadings exceeding the design values. In this regard, care
should be taken during the backfilling operations.
Groundwater/Waterproofing
Groundwater was encountered within about 6.5 to 7 feet of the ground surface. Groundwater could be higher
at times in the future. We recommend that the designer consider groundwater as high as 2 feet from the
ground surface. Accordingly, any below grade rooms will require design and construction with “boat-like”
waterproofing and waste slab concrete sufficient to offset the buoyant uplift.
If retaining walls form portions of the building interiors, very special consideration should be given to
waterproofing of the walls to prevent damage to the building interior. Unless dampness is acceptable on
exterior wall faces, waterproofing should also be incorporated into the exterior retaining wall design.
Even though groundwater is not expected to be a problem for at grade construction at this site, extreme care
should be exercised in sealing walls against water and water vapor migration. Where retaining walls are
planned against the interior space, continuity should be provided between the aforementioned wall moisture
proofing on the back of the retaining wall and the moisture barrier typically placed under the slab areas. This
waterproofing is necessary to prevent the foundation concrete acting as a wick through which moisture
migrates to the interior space despite the wall moisture proofing. The architect or structural engineer should
develop the actual waterproofing details.
File No. 34165-01 May 5, 2020 Page 13
4.7 Exterior Flatwork
If the exterior flatwork is considered, it should be placed over newly placed compacted fill. The new exterior
flatwork should be at least 6 inches thick with No. 4 bars at 12 inches on center, each way. As recommended for
interior slabs, a four-inch thick crushed rock base under the slab and above the subgrade is also suggested. At
least two No. 4 bars should be planned within the perimeter 6 inches and within 6 inches of planned control
joints. Control joints should be planned at not more than 12-foot spacing for larger concrete areas such as the
driveway and patio areas. Narrower areas of flatwork such as walkways should have control joints planned at
not greater than 1.5 times the width of the walkway. Additionally, it is also recommended that at least 12-inch
deepened footings be constructed along the edges of the patio slab and larger concrete flatwork.
Movement of exterior slabs adjacent to structures can be mitigated by doweling slabs to perimeter footings.
Doweling should consist of No. 4 bars bent around exterior footing reinforcement. Dowels should be extended at
least 2 feet into planned exterior slabs. Doweling should be spaced consistent with the patio reinforcement
schedule. With doweling, 3/8-inch minimum thickness expansion joint material should be provided. Where
expansion joint material is provided, it should be held down about 3/8 inch below the surface. The expansion
joints should be finished with a color matched, flowing, flexible sealer (e.g., pool deck compound) sanded to add
mortar-like texture. As an option to doweling, an architectural separation could be provided between the main
structures and abutting appurtenant improvements.
4.8 Concrete
We recommend that low-permeable concrete be utilized for the project. For this purpose, the water-to-cement
ratio in the concrete should be limited to 0.45 (0.42 preferred). A minimum concrete compressive strength of
4,500 is also recommended. Use of utilizing Type V cement is also preferred. Limited use (subject to approval
of mix designs) of a water-reducing agent may be included to increase workability. The concrete should be
properly cured to minimize risk of shrinkage cracking. One-inch hard rock mixes are recommended. Pea-
gravel mixes are specifically not recommended but could be utilized for relatively non-critical improvements
(e.g., flatwork) and other improvements provided the mix designs consider limiting shrinkage.
Contractors/other designers should take care in all aspects of designing mixes, detailing, placing, finishing, and
curing concrete. The mix designers and contractor are advised to consider all available steps to reduce
cracking. The use of shrinkage compensating cement or fiber reinforcing should be considered. Mix designs
proposed by the contractor should be considered subject to review by the project engineer.
4.9 Corrosion Potential
File No. 34165-01 May 5, 2020 Page 14
In addition to sulfate tests, Chloride, pH, and resistivity tests on near-surface site soil were performed. Results
of these tests are presented in Appendix C. Appropriate design considerations should be made for the risk of
damage from corrosion. The use of STHD style strap anchors should not be permitted unless stainless steel.
Perimeter anchor bolts should be hot-dipped galvanized or epoxy coated. More advice on corrosion risk can
be provided, if needed.
4.10 Plan Review
When detailed grading and structural plans are developed, they should be forwarded to this office for review
and comment.
4.11 Field Construction Review
During construction, a number of reviews by this office are recommended to verify the site geotechnical
conditions and conformance with the intentions of the recommendations for construction. Although not all
possible geotechnical observation and testing services are required by the City, the more site
reviews requested, the lower the risk of future problems. The following site reviews are advised, some of
which will probably be required by the agencies.
Preconstruction/pregrading meeting ............................................................... Advised
Soil and geologic observation and testing during any grading ....................... Required
Foundation excavation .................................................................................. Required
Subgrade preparation for slabs ..................................................................... Required
Reinforcement for slab/foundations ................................................................ Advised
Unless otherwise agreed to in writing, all supplemental consulting services will be provided on an as-needed,
time-and-expense fee schedule basis.
5.0 REMARKS
Only a portion of subsurface conditions have been reviewed and evaluated. Conclusions, recommendations,
and other information contained in this report are based upon the assumptions that subsurface conditions do
not vary appreciably between and adjacent to observation points. Although no significant variation is
anticipated, it must be recognized that variations can occur.
File No. 34165-01 May 5, 2020 Page 15
This report has been prepared for the sole use and benefit of our client. The intent of the report is to advise
our client on geotechnical matters involving the proposed improvements. It should be understood that the
geotechnical consulting provided and the contents of this report are not perfect. Any errors or omissions noted
by any party reviewing this report, and/or any other geotechnical aspect of the project, should be reported to
this office in a timely fashion. The client is the only party intended by this office to directly receive the advice.
Subsequent use of this report can only be authorized by the client. Any transferring of information or other
directed use by the client should be considered "advice by the client."
Geotechnical engineering is characterized by uncertainty. Geotechnical engineering is often described as an
inexact science or art. Conclusions and recommendations presented herein are partly based upon the
evaluations of technical information gathered, partly on experience, and partly on professional judgment. The
conclusions and recommendations presented should be considered "advice." Other consultants could arrive at
different conclusions and recommendations. Typically, "minimum" recommendations have been presented.
Although some risk will always remain, lower risk of future problems would usually result if more restrictive
criteria were adopted. Final decisions on matters presented are the responsibility of the client and/or the
governing agencies. No warranties in any respect are made as to the performance of the project.
File No. 34165-01 May 5, 2020
REFERENCES
California Geological Survey Staff, 1998, Official Seismic Hazard Zone Map, Newport Beach
quadrangle: California Geological Survey, Official Map of Seismic Hazard Zones, scale 1:24,000.
California Division of Mines and Geology staff, 2001, Seismic Hazard Zone Report for the Anaheim and
Newport Beach 7.5-minute quadrangles, Orange County, California: California Division of Mines and
Geology, Seismic Hazard Zone Report 003, scale 1:24,000.
California Geological Survey Staff, 3/15/09, Tsunami Inundation Map for Emergency Planning Newport
Beach Quadrangle, scale 1:24,000.
Morton, P.K., Miller, R.V., and Evans, J.R., 1976, Environmental geology of Orange County, California.:
California Division of Mines and Geology, Open-File Report 79-08, scale 1:48,000.
SITE LOCATION MAP
34165-01MAY 2020N.T.S
PLATEAMERICAN GEOTECHNICAL, INC.122725 Old Canal Road, Yorba Linda, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
TITLE:
1616 West Oceanfront, Newport Beach, CA
FILE NO.:DATE:SCALE:
AERIAL VIEW/ BORING LOCATION MAP
34165-01MAY 2020N.T.S
PLATEAMERICAN GEOTECHNICAL, INC.222725 Old Canal Road, Yorba Linda, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
1616 West Oceanfront, Newport Beach, CA
FILE NO.:DATE:SCALE:
Legend AGSB-2
AGSB-2
Approximate location of boring
AGSB-1
N
1616 West
Oceanfront
File No. 34165-01 May 5, 2020
APPENDIX A
Boring Logs
File No. 34165-01 May 5, 2020
APPENDIX B
Summary of Laboratory Data
File No. 34165-01 May 5, 2020
APPENDIX C
Liquefaction Analysis
File No. 34165-01 May 5, 2020
APPENDIX D
Geotechnical Guidelines for Grading Project
22725 Old Canal Road, Yorba Linda, CA 92887 - (714) 685-3900 - FAX (714) 685-3909
2640 Financial Court, Suite A, San Diego, CA 92117 - (858) 450-4040 - FAX (858) 457-0814
3100 Fite Circle, Suite 103, Sacramento, CA 95827 - (916) 368-2088 - FAX (916) 368-2188
5600 Spring Mountain Road, Suite 201, Las Vegas, NV 89146 - (702) 562-5046 - FAX (702) 562-2457
GEOTECHNICAL GUIDELINES FOR GRADING PROJECTS
22725 Old Canal Road, Yorba Linda, CA 92887 - (714) 685-3900 - FAX (714) 685-3909
2640 Financial Court, Suite A, San Diego, CA 92117 - (858) 450-4040 - FAX (858) 457-0814
3100 Fite Circle, Suite 103, Sacramento, CA 95827 - (916) 368-2088 - FAX (916) 368-2188
5600 Spring Mountain Road, Suite 201, Las Vegas, NV 89146 - (702) 562-5046 - FAX (702) 562-2457
TABLE OF CONTENTS
A. GENERAL ........................................................................................................................................... 1
B. DEFINITIONS OF TERMS .................................................................................................................. 2
C. OBLIGATIONS OF PARTIES ............................................................................................................. 6
D. SITE PREPARATION ......................................................................................................................... 7
E. SITE PROTECTION ............................................................................................................................ 8
F. EXCAVATIONS ................................................................................................................................ 10
F1 UNSUITABLE MATERIALS .................................................................................................. 10
F2 CUT SLOPES ....................................................................................................................... 10
F3 PAD AREAS ......................................................................................................................... 11
G. COMPACTED FILL ........................................................................................................................... 12
G1 PLACEMENT ........................................................................................................................ 12
G2 MOISTURE ........................................................................................................................... 14
G3 FILL MATERIAL .................................................................................................................... 14
G4 FILL SLOPES ....................................................................................................................... 16
G5 OFF-SITE FILL ..................................................................................................................... 19
H. DRAINAGE ....................................................................................................................................... 20
I STAKING .......................................................................................................................................... 21
J. MAINTENANCE ................................................................................................................................ 22
J1 LANDSCAPE PLANTS ......................................................................................................... 22
J2 IRRIGATION ......................................................................................................................... 22
J3 MAINTENANCE .................................................................................................................... 22
J4 REPAIRS .............................................................................................................................. 23
K. TRENCH BACKFILL ......................................................................................................................... 24
L STATUS OF GRADING .................................................................................................................... 25
STANDARD DETAILS NOS. 1-9
1 CANYON SUBDRAIN
2 FILL OVER NATURAL/ CUT SLOPE
3 STABILIZATION/ BUTRESS FILL
4 STABILIZATION FILL
5 FUTURE CANYON FILL
6 TRANSITION LOT OVEREXCAVATION
7 ROCK DISPOSAL
8 MINOR SLOPE REPAIR
9 LOT DRAINAGE
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 1
GEOTECHNICAL GUIDELINES FOR GRADING PROJECTS
A. GENERAL
Al The guidelines contained herein and the standard details attached hereto represent this
firm's standard recommendations for grading and other associated operations on
construction projects. These guidelines should be considered a portion of the project
specifications.
A2 All plates attached hereto shall be considered as part of these guidelines.
A3 The Contractor should not vary from these guidelines without prior recommendation by the
Geotechnical Consultant and the approval of the Client or his authorized representative.
Recommendations by the Geotechnical Consultant and/or Client should not be considered to
preclude requirements for approval by the controlling agency prior to the execution of any
changes.
A4 These Standard Grading Guidelines and Standard Details may be modified and/or
superseded by recommendations contained in the text of the preliminary geotechnical report
and/or subsequent reports.
A5 If disputes arise out of the interpretation of these grading guidelines or standard details, the
Geotechnical Consultant shall provide the governing interpretation.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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B. DEFINITIONS OF TERMS
Bl ALLUVIUM - unconsolidated detrital deposits resulting from flow of water, including
sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes and
estuaries.
B2 AS-GRADED (AS-BUILT) - the surface and subsurface conditions at completion of grading.
B3 BACKCUT - a temporary construction slope at the rear of earth retaining structures such as
buttresses, shear keys, stabilization fills or retaining walls.
B4 BACKDRAIN - generally a pipe and gravel or similar drainage system placed behind earth
retaining structures such as buttresses, stabilization fills and retaining walls.
B5 BEDROCK - a more or less solid, relatively undisturbed rock in place either at the surface or
beneath superficial deposits of soil.
B6 BENCH - a relatively level step and near vertical rise excavated into sloping ground on which
fill is to be placed.
B7 BORROW (Import) - any fill material hauled to the project site from off-site areas.
B8 BUTTRESS FILL - a fill mass, the configuration of which is designed by engineering
calculations to stabilize a slope exhibiting adverse geologic features. A buttress is generally
specified by minimum key width and depth and by maximum backcut angle. A buttress
normally contains a backdrain system.
B9 CIVIL ENGINEER - the Registered Civil Engineer or consulting firm responsible for
preparation of the grading plans, surveying and verifying as-graded topographic conditions.
B10 CLIENT - the Developer or his authorized representative who is chiefly in charge of the
project. He shall have the responsibility of reviewing the findings and recommendations
made by the Geotechnical Consultant and shall authorize the Contractor and/or other
consultants to perform work and/or provide services.
B11 COLLUVIUM - generally loose deposits usually found near the base of slopes and brought
there chiefly by gravity through slow continuous downhill creep (also see Slope Wash).
B12 COMPACTION - is the densification of a fill by mechanical means.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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B13 CONTRACTOR - a person or company under contract or otherwise retained by the Client to
perform demolition, grading and other site improvements.
B14 DEBRIS - all products of clearing, grubbing, demolition, contaminated soil material
unsuitable for reuse as compacted fill and/or any other material so designated by the
Geotechnical Consultant.
B15 ENGINEERING GEOLOGIST - a Geologist holding a valid certificate of registration in the
specialty of Engineering Geology.
B16 ENGINEERED FILL - a fill of which the Geotechnical Consultant or his representative, during
grading, has made sufficient tests to enable him to conclude that the fill has been placed in
substantial compliance with the recommendations of the Geotechnical Consultant and the
governing agency requirements.
B17 EROSION - the wearing away of the ground surface as a result of the movement of wind,
water and/or ice.
B18 EXCAVATION - the mechanical removal of earth materials.
B19 EXISTING GRADE - the ground surface configuration prior to grading.
B20 FILL - any deposits of soil, rock, soil-rock blends or other similar materials placed by man.
B21 FINISH GRADE - the ground surface configuration at which time the surface elevations
conform to the approved plan.
B22 GEOFABRIC - any engineering textile utilized in geotechnical applications including
subgrade stabilization and filtering.
B23 GEOLOGIST - a representative of the Geotechnical Consultant educated and trained in the
field of geology.
B24 GEOTECHNICAL CONSULTANT - the Geotechnical Engineering and Engineering Geology
consulting firm retained to provide technical services for the project. For the purpose of
these guidelines, observations by the Geotechnical Consultant include observations by the
Soil Engineer, Geotechnical Engineer, Engineering Geologist and those performed by
persons employed by and responsible to the Geotechnical Consultants.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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B25 GEOTECHNICAL ENGINEER - a licensed Civil Engineer who applies scientific methods,
engineering principles and professional experience to the acquisition, interpretation and use
of knowledge of materials of the earth's crust for the evaluation of engineering problems.
Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics,
rock mechanics, geology, geophysics, hydrology and related sciences.
B26 GRADING - any operation consisting of excavation, filling or combinations thereof and
associated operations.
B27 LANDSLIDE DEBRIS - material, generally porous and of low density, produced from
instability of natural or man-made slopes.
B28 MAXIMUM DENSITY - standard laboratory test for maximum dry unit weight. Unless
otherwise specified, the maximum dry unit weight shall be determined in accordance with
ASTM Method of Test D 1557-78.
B29 OPTIMUM MOISTURE - test moisture content at the maximum density.
B30 RELATIVE COMPACTION - the degree of compaction (expressed as a percentage) of dry
unit weight of a material as compared to the maximum dry unit weight of the material.
B31 ROUGH GRADE - the ground surface configuration at which time the surface elevations
approximately conform to the approved plan.
B32 SITE - the particular parcel of land where grading is being performed.
B33 SHEAR KEY - similar to buttress, however, it is generally constructed by excavating a slot
within a natural slope in order to stabilize the upper portion of the slope without grading
encroaching into the lower portion of the slope.
B34 SLOPE - is an inclined ground surface the steepness of which is generally specified as a
ratio of horizontal:vertical (e.g., 2:1).
B35 SLOPE WASH - soil and/or rock material that has been transported down a slope by mass
wasting assisted by runoff water not confined by channels (also see Colluvium).
B36 SOIL - naturally occurring deposits of sand, silt, clay, etc. or combinations thereof.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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B37 SOIL ENGINEER - licensed Civil Engineer experienced in soil mechanics (also see
Geotechnical Engineer).
B38 STABILIZATION FILL - a fill mass, the configuration of which is typically related to slope
height and is specified by the standards of practice for enhancing the stability of locally
adverse conditions. A stabilization fill is normally specified by minimum key width and depth
and by maximum backcut angle. A stabilization fill may or may not have a backdrain system
specified.
B39 SUBDRAIN - generally a pipe and gravel or similar drainage system placed beneath a fill in
the alignment of canyons or former drainage channels.
B40 SLOUGH - loose, noncompacted fill material generated during grading operations.
B41 TAILINGS - non-engineered fill which accumulates on or adjacent to equipment haul-roads.
B42 TERRACE - relatively level step constructed in the face of a graded slope surface for
drainage control and maintenance purposes.
B43 TOPSOIL - the presumably fertile upper zone of soil which is usually darker in color and
loose.
B44 WINDROW - a string of large rock buried within engineered fill in accordance with guidelines
set forth by the Geotechnical Consultant.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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C. OBLIGATIONS OF PARTIES
C1 The Geotechnical Consultant should provide observation and testing services and should
make evaluations to advise the Client on geotechnical matters. The geotechnical Consultant
should report his findings and recommendations to the Client or his authorized
representative.
C2 The Client should be chiefly responsible for all aspects of the project. He or his authorized
representative has the responsibility of reviewing the findings and recommendations of the
Geotechnical Consultant. He shall authorize or cause to have authorized the Contractor
and/or other consultants to perform work and/or provide services. During grading the Client
or his authorized representative should remain on-site or should remain reasonably
accessible to all concerned parties in order to make decisions necessary to maintain the flow
of the project.
C3 The Contractor should be responsible for the safety of the project and satisfactory
completion of all grading and other associated operations on construction projects, including,
but not limited to, earth work in accordance with the project plans, specifications and
controlling agency requirements. During grading, the Contractor or his authorized
representative should remain on-site. Overnight and on days off, the Contractor should
remain accessible.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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D. SITE PREPARATION
D1 The Client, prior to any site preparation or grading, should arrange and attend a meeting
among the Grading Contractor, the Design Engineer, the Geotechnical Consultant,
representatives of the appropriate governing authorities as well as any other concerned
parties. All parties should be given at least 48 hours notice.
D2 Clearing and grubbing should consist of the removal of vegetation such as brush, grass,
woods, stumps, trees, roots of trees and otherwise deleterious natural materials from the
areas to be graded. Clearing and grubbing should extend to the outside of all proposed
excavation and fill areas.
D3 Demolition should include removal of buildings, structures, foundations, reservoirs, utilities
(including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining
shafts, tunnels, etc.) and other man-made surface and subsurface improvements from the
areas to be graded. Demolition of utilities should include proper capping and/or rerouting
pipelines at the project perimeter and cutoff and capping of wells in accordance with the
requirements of the governing authorities and the recommendations of the Geotechnical
Consultant at the time of demolition.
D4 Trees, plants or man-made improvements not planned to be removed or demolished should
be protected by the Contractor from damage.
D5 Debris generated during clearing, grubbing and/or demolition operations should be wasted
from areas to be graded and disposed off-site. Clearing, grubbing and demolition operations
should be performed under the observation of the Geotechnical Consultant.
D6 The Client or Contractor should obtain the required approvals from the controlling authorities
for the project prior, during and/or after demolition, site preparation and removals, etc. The
appropriate approvals should be obtained prior to proceeding with grading operations.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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E SITE PROTECTION
El Protection of the site during the period of grading should be the responsibility of the
Contractor. Unless other provisions are made in writing and agreed upon among the
concerned parties, completion of a portion of the project should not be considered to
preclude that portion or adjacent areas from the requirements for site protection until such
time as the entire project is complete as identified by the Geotechnical Consultant, the Client
and the regulating agencies.
E2 The Contractor should be responsible for the stability of all temporary excavations.
Recommendations by the Geotechnical Consultant pertaining to temporary excavations
(e.g., backcuts) are made in consideration of stability of the completed project and, therefore,
should not be considered to preclude the responsibilities of the Contractor.
Recommendations by the Geotechnical Consultant should not be considered to preclude
more restrictive requirements by the regulating agencies.
E3 Precautions should be taken during the performance of site clearing, excavations and
grading to protect the work site from flooding, ponding or inundation by poor or improper
surface drainage. Temporary provisions should be made during the rainy season to
adequately direct surface drainage away from and off the work site. Where low areas cannot
be avoided, pumps should be kept on hand to continually remove water during periods of
rainfall.
E4 During periods of rainfall, plastic sheeting should be kept reasonably accessible to prevent
unprotected slopes from becoming saturated. Where necessary during periods of rainfall,
the Contractor should install checkdams, desilting basins, rip-rap, sand bags or other devices
or methods necessary to control erosion and provide safe conditions.
E5 During periods of rainfall, the Geotechnical Consultant should be kept informed by the
Contractor as to the nature of remedial or preventative work being performed (e.g., pumping,
placement of sandbags or plastic sheeting, other labor, dozing, etc.).
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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E6 Following periods of rainfall, the Contractor should contact the Geotechnical Consultant and
arrange a walkover of the site in order to visually assess rain related damage. The
Geotechnical Consultant may also recommend excavations and testing in order to aid in his
assessments. At the request of the Geotechnical Consultant, the Contractor shall make
excavations in order to evaluate the extent of rain related-damage.
E7 Rain-related damage should be considered to include, but may not be limited to, erosion,
silting, saturation, swelling, structural distress and other adverse conditions identified by the
Geotechnical Consultant. Soil adversely affected should be classified as Unsuitable
Materials and should be subject to overexcavation and replacement with compacted fill or
other remedial grading as recommended by the Geotechnical Consultant.
E8 Relatively level areas, where saturated soils and/or erosion gullies exist to depths of greater
than 1.0 foot, should be overexcavated to unaffected, competent material. Where less than
1.0 foot in depth, unsuitable materials may be processed in-place to achieve near-optimum
moisture conditions, then thoroughly recompacted in accordance with the applicable
specifications. If the desired results are not achieved, the affected materials should be
overexcavated, then replaced in accordance with the applicable specifications.
E9 In slope areas, where saturated soil and/or erosion gullies exist to depths of greater than 1.0
foot, they should be overexcavated and replaced as compacted fill in accordance with the
applicable specifications. Where affected materials exist to depths of 1.0 foot or less below
proposed finished grade, remedial grading by moisture conditioning in-place, followed by
thorough recompaction in accordance with the applicable grading guidelines herein may be
attempted. If the desired results are not achieved, all affected materials should be
overexcavated and replaced as compacted fill in accordance with the slope repair
recommendations herein. As field conditions dictate, other slope repair procedures may be
recommended by the Geotechnical Consultant.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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F. EXCAVATIONS
F1 UNSUITABLE MATERIALS
F1.1 Materials which are unsuitable should be excavated under observation and
recommendations of the Geotechnical Consultant. Unsuitable materials include, but
may not be limited to, dry, loose, soft, wet, organic compressible natural soils and
fractured, weathered, soft bedrock and nonengineered or otherwise deleterious fill
materials.
F1.2 Material identified by the Geotechnical Consultant as unsatisfactory due to it's
moisture condition should be overexcavated, watered or dried, as needed, and
thoroughly blended to a uniform near optimum moisture condition prior to placement
as compacted fill.
F2 CUT SLOPES
F2.1 Unless otherwise recommended by the Geotechnical Consultant and approved by
the regulating agencies, permanent cut slopes should not be steeper than 2:1
(horizontal: vertical).
F2.2 If excavations for cut slopes expose loose, cohesionless, significantly fractured or
otherwise unsuitable material, overexcavation and replacement of the unsuitable
materials with a compacted stabilization fill should be accomplished as
recommended by the Geotechnical Consultant. Unless otherwise specified by the
Geotechnical Consultant, stabilization fill construction should conform to the
requirements of the Standard Details.
F2.3 The Geotechnical Consultant should review cut slopes during excavation. The
Geotechnical Consultant should be notified by the contractor prior to beginning slope
excavations.
F2.4 If, during the course of grading, adverse or potentially adverse geotechnical
conditions are encountered which were not anticipated in the preliminary report, the
Geotechnical Consultant should explore, analyze and make recommendations to
treat these problems.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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F2.5 When cut slopes are made in the direction of the prevailing drainage, a non-erodible
diversion swale (brow ditch) should be provided at the top-of-cut.
F3 PAD AREAS
F3.1 All lot pad areas, including side yard terraces, above stabilization fill or buttresses
should be overexcavated to provide for a minimum of 3 feet (refer to Standard
Details) of compacted fill over the entire pad area. Pad areas with both fill and cut
materials exposed and pad areas containing both very shallow (less than 3 feet) and
deeper fill should be overexcavated to provide for a uniform compacted fill blanket
with a minimum of 3 feet in thickness (refer to Standard Details). Cut areas exposing
significantly varying material types should also be overexcavated to provide for at
least a 3-foot thick compacted fill blanket. Geotechnical conditions may require
greater depth of overexcavation. The actual depth should be delineated by the
Geotechnical Consultant during grading.
F3.2 For pad areas created above cut or natural slopes, positive drainage should be
established away from the top-of-slope. This may be accomplished utilizing a berm
and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-
slopes of 2 percent or greater is recommended.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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G. COMPACTED FILL
All fill materials should be compacted as specified below or by other methods specifically
recommended by the Geotechnical Consultant. Unless otherwise specified, the minimum degree of
compaction (relative compaction) should be 90 percent of the laboratory maximum density.
G1 PLACEMENT
G1.1 Prior to placement of compacted fill, the Contractor should request a review by the
Geotechnical Consultant of the exposed ground surface. Unless otherwise
recommended, the exposed ground surface should then be scarified (six inches
minimum), watered or dried as needed, thoroughly blended to achieve near optimum
moisture conditions, then thoroughly compacted to a minimum of 90 percent of the
maximum density. The review by the Geotechnical Consultant should not be
considered to preclude requirement of inspection and approval by the governing
agency.
G1.2 Compacted fill should be placed in thin horizontal lifts not exceeding eight inches in
loose thickness prior to compaction. Each lift should be watered or dried as needed,
thoroughly blended to achieve near optimum moisture conditions then thoroughly
compacted by mechanical methods to a minimum of 90 percent of laboratory
maximum dry density. Each lift should be treated in a like manner until the desired
finished grades are achieved.
G1.3 The Contractor should have suitable and sufficient mechanical compaction
equipment and watering apparatus on the job site to handle the amount of fill being
placed in consideration of moisture retention properties of the materials. If
necessary, excavation equipment should be "shut down" temporarily in order to
permit proper compaction of fills. Earth moving equipment should only be
considered a supplement and not substituted for conventional compaction
equipment.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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G1.4 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1
(horizontal: vertical), horizontal keys and vertical benches should be excavated into
the adjacent slope area. Keying and benching should be sufficient to provide at least
six-foot wide benches and a minimum of four feet of vertical bench height within the
firm natural ground, firm bedrock or engineered compacted fill. No compacted fill
should be placed in an area subsequent to keying and benching until the area has
been reviewed by the Geotechnical Consultant. Material generated by the benching
operation should be moved sufficiently away from the bench area to allow for the
recommended review of the horizontal bench prior to placement of fill. Typical
keying and benching details have been included within the accompanying Standard
Details.
G1.5 Within a single fill area where grading procedures dictate two or more separate fills,
temporary slopes (false slopes) may be created. When placing fill adjacent to a false
slope, benching should be conducted in the same manner as above described. At
least a 3-foot vertical bench should be established within the firm core of adjacent
approved compacted fill prior to placement of additional fill. Benching should
proceed in at least 3-foot vertical increments until the desired finished grades are
achieved.
G1.6 Fill should be tested for compliance with the recommended relative compaction and
moisture conditions. Field density testing should conform to ASTM Method of Test
D1556-64, D2922-78 and/or D2937-71. Tests should be provided for about every
two vertical feet or 1,000 cubic yards of fill placed. Actual test interval may vary as
field conditions dictate. Fill found not to be in conformance with the grading
recommendations should be removed or otherwise handled as recommended by the
Geotechnical Consultant.
G1.7 The Contractor should assist the Geotechnical Consultant and/or his representative
by digging test pits for removal determinations and/or for testing compacted fill.
G1.8 As recommended by the Geotechnical Consultant, the Contractor should "shut down"
or remove grading equipment from an area being tested.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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G1.9 The Geotechnical Consultant should maintain a plan with estimated locations of field
tests. Unless the client provides for actual surveying of test locations, the estimated
locations by the Geotechnical Consultant should only be considered rough estimates
and should not be utilized for the purpose of preparing cross sections showing test
locations or in any case for the purpose of after-the-fact evaluating of the sequence
of fill placement.
G2 MOISTURE
G2.1 For field testing purposes, "near optimum" moisture will vary with material type and
other factors including compaction procedure. "Near optimum" may be specifically
recommended in Preliminary Investigation Reports and/or may be evaluated during
grading. As a preliminary guideline "near optimum" should be considered from one
percent below to three percent above optimum.
G2.2 Prior to placement of additional compacted fill following an overnight or other grading
delay, the exposed surface or previously compacted fill should be processed by
scarification, watered or dried as needed, thoroughly blended to near-optimum
moisture conditions, then recompacted to a minimum of 90 percent of laboratory
maximum dry density. Where wet or other dry or other unsuitable materials exist to
depths of greater than one foot, the unsuitable materials should be over excavated.
G2.3 Following a period of flooding, rainfall or overwatering by other means, no additional
fill should be placed until damage assessments have been made and remedial
grading performed as described under Section E6 herein.
G3 FILL MATERIAL
G3.1 Excavated on-site materials which are acceptable to the Geotechnical Consultant
may be utilized as compacted fill, provided trash, vegetation and other deleterious
materials are removed prior to placement.
G3.2 Where import materials are required for use on-site, the Geotechnical Consultant
should be notified at least 72 hours in advance of importing, in order to sample and
test materials from proposed borrow sites. No import materials should be delivered
for use on-site without prior sampling and testing by the Geotechnical Consultant.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 15
G3.3 Where oversized rock or similar irreducible material is generated during grading, it is
recommended, where practical, to waste such material off-site or on-site in areas
designated as "nonstructural rock disposal areas". Rock placed in disposal areas
should be placed with sufficient fines to fill voids. The rock should be compacted in
lifts to an unyielding condition. The disposal area should be covered with at least
three feet of compacted fill which is free of oversized material. The upper three feet
should be placed in accordance with the guidelines for compacted fill herein.
G3.4 Rocks 12 inches in maximum dimension and smaller may be utilized within the
compacted fill, provided they are placed in such a manner that nesting of the rock is
avoided. Fill should be placed and thoroughly compacted over and around all rock.
The amount of rock should not exceed 40 percent by dry weight passing the 3/4-inch
sieve size. The 12-inch and 40 percent recommendations herein may vary as field
conditions dictate.
G3.5 During the course of grading operations, rocks or similar irreducible materials greater
than 12 inches maximum dimension (oversized material), may be generated. These
rocks should not be placed within the compacted fill unless placed as recommended
by the Geotechnical Consultant.
G3.6 Where rocks or similar irreducible materials of greater than 12 inches but less than
four feet of maximum dimension are generated during grading, or otherwise desired
to be placed within an engineered fill, special handling in accordance with the
accompanying Standard Details is recommended. Rocks greater than four feet
should be broken down or disposed off-site. Rocks up to four feet maximum
dimension should not be placed in the upper 10 feet of any fill and should not be
closer than 20 feet to any slope face. These recommendations could vary as
locations of improvements dictate.
Where practical, oversized material should not be placed below areas where
structures or deep utilities are proposed. Oversized material should be placed in
windrows on a clean, overexcavated or unyielding compacted fill or firm natural
ground surface. Select native or imported granular soil (S.E. 30 or higher) should be
placed and thoroughly flooded over and around all windrowed rock, such that voids
are filled. Windrows of oversized material should be staggered so that successive
strata of oversized material are not in the same vertical plane.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 16
The Contractor should be aware that the placement of rock in windrows will
significantly slow the grading operation and may require additional equipment and/or
special equipment.
G3.7 It may be possible to dispose of individual larger rock as field conditions dictate and
as recommended by the Geotechnical Consultant at the time of placement.
G3.8 Material that is considered unsuitable by the Geotechnical Consultant should not be
utilized in the compacted fill.
G3.9 During grading operations, placing and mixing the materials from the cut and/or
borrow areas may result in soil mixtures which possess unique physical properties.
Testing may be required of samples obtained directly from the fill areas in order to
verify conformance with the specifications. Processing of these additional samples
may take two or more working days. The contractor may elect to move the operation
to other areas within the project, or may continue placing compacted fill pending
laboratory and field test results. Should he elect the second alternative, fill placed is
done so at the Contractor's risk.
G3.10 Any fill placed in areas not previously reviewed and evaluated by the Geotechnical
Consultant, and/or in other areas, without prior notification to the Geotechnical
Consultant may require removal and recompaction at the Contractor's expense.
Determination of overexcavations should be made upon review of field conditions by
the Geotechnical Consultant.
G4 FILL SLOPES
G4.1 Unless otherwise recommended by the Geotechnical Consultant and approved by
the regulating agencies, permanent fill slopes should not be steeper than 2:1
(horizontal: vertical).
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
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G4.2 Except as specifically recommended otherwise or as otherwise provided for in these
grading guidelines (Reference G4.3), compacted fill slopes should be overbuilt and
cut back to grade, exposing the firm, compacted fill inner core. The actual amount of
overbuilding may vary as field conditions dictate. If the desired results are not
achieved, the existing slopes should be overexcavated and reconstructed under the
guidelines of the Geotechnical Consultant. The degree of overbuilding shall be
increased until the desired compacted slope surface condition is achieved. Care
should be taken by the Contractor to provide thorough mechanical compaction to the
outer edge of the overbuilt slope surface.
G4.3 Although no construction procedure produces a slope free from risk of future
movement, overfilling and cutting back of slope to a compacted inner core is, given
no other constraints, the most desirable procedure. Other constraints, however,
must often be considered. These constraints may include property line situations,
access, the critical nature of the development and cost. Where such constraints are
identified, slope face compaction on slopes of 2:1 or flatter may be attempted as a
second-best alternative by conventional construction procedures including
backrolling techniques upon specific recommendation by the Geotechnical
Consultant.
Fill placement should proceed in thin lifts, (i.e., six to eight-inch loose thickness).
Each lift should be moisture conditioned and thoroughly compacted. The desired
moisture condition should be maintained and/or re-established, where necessary,
during the period between successive lifts. Selected lifts should be tested to
ascertain that desired compaction is being achieved. Care should be taken to extend
compactive effort to the outer edge of the slope.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 18
Each lift should extend horizontally to the desired finished slope surface or more as
needed to ultimately establish desired grades. Grade during construction should not
be allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the
outer edge of the slope. Slough resulting from the placement of individual lifts should
not be allowed to drift down over previous lifts. At intervals not exceeding four feet in
vertical slope height or the capability of available equipment, whichever is less, fill
slopes should be thoroughly backrolled utilizing a conventional sheepsfoot-type
roller. Care should be taken to maintain the desired moisture conditions and/or
reestablishing same as needed prior to backrolling. Upon achieving final grade, the
slopes should again be moisture conditioned and thoroughly backrolled. The use of
a side-boom roller will probably be necessary and vibratory methods are strongly
recommended. Without delay, so as to avoid (if possible) further moisture
conditioning, the slopes should then be grid-rolled to achieve a relatively smooth
surface and uniformly compact condition.
In order to monitor slope construction procedures, moisture and density tests should
be taken at regular intervals. Failure to achieve the desired results will likely result in
a recommendation by the Geotechnical Consultant to overexcavate the slope
surfaces followed by reconstruction of the slopes utilizing over-filling and cutting back
procedures and/or further attempt at the conventional backrolling approach. Other
recommendations may also be provided which would be commensurate with field
conditions.
G4.4 Where placement of fill above a natural slope or above a cut slope is proposed, the
fill slope configuration as presented in the accompanying Standard Details should be
adopted.
G4.5 For pad areas above fill slopes, positive drainage should be established away from
the top-of-slope. This may be accomplished utilizing a berm and pad gradients of at
least 2 percent in soil areas.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 19
G5 OFF-SITE FILL
G5.1 Off-site fill should be treated in the same manner as recommended in these
specifications for site preparation, excavation, drains, compaction, etc.
G5.2 Off-site canyon fill should be placed in preparation for future additional fill, as shown
in the accompanying Standard Details.
G5.3 Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for
future relocation and connection.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 20
H. DRAINAGE
H1 Canyon subdrain systems specified by the Geotechnical Consultant should be installed in
accordance with the Standard Details.
H2 Typical subdrains for compacted fill buttresses, slope stabilizations or sidehill masses,
should be installed in accordance with the specifications of the accompanying Standard
Details.
H3 Roof, pad and slope drainage should be directed away from slopes and areas of structures
to suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, concrete
swales).
H4 For drainage over soil areas immediately away from structures, (i.e., within four feet) a
minimum of 5 percent gradient should be maintained. Pad drainage of at least 2 percent
should be maintained over soil areas.
H5 Drainage patterns established at the time of fine grading should be maintained throughout
the life of the project. Property owners should be made aware that altering drainage patterns
can be detrimental to slope stability and foundation performance.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 21
I STAKING
I1 In all fill areas, the fill should be compacted prior to the placement of the stakes. This
particularly is important on fill slopes. Slope stakes should not be placed until the slope is
thoroughly compacted (backrolled). If stakes must be placed prior to the completion of
compaction procedures, it must be recognized that they will be removed and/or demolished
at such time as compaction procedures resume.
12 In order to allow for remedial grading operations, which could include overexcavations or
slope stabilization, appropriate staking offsets should be provided. For finished slope and
stabilization backcut areas, we recommend at least a 10-foot setback from proposed toes
and tops-of-cut.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 22
J. MAINTENANCE
J1 LANDSCAPE PLANTS
In order to enhance surficial slope stability, slope planting should be accomplished at the
completion of grading. Slope planting should consist of deep-rooting vegetation requiring
little watering. Plants native to the southern California area and plants relative to native
plants are generally desirable. Plants native to other semi-arid and arid areas may also be
appropriate. A Landscape Architect would be the best party to consult regarding actual
types of plants and planting configuration.
J2 IRRIGATION
J2.1 Irrigation pipes should be anchored to slope faces, not placed in trenches excavated
into slope faces.
J2.2 Slope irrigation should be minimized. If automatic timing devices are utilized on
irrigation systems, provisions should be made for interrupting normal irrigation during
periods of rainfall.
J2.3 Though not a requirement, consideration should be given to the installation of near-
surface moisture monitoring control devices. Such devices can aid in the
maintenance of relatively uniform and reasonably constant moisture conditions.
J2.4 Property owners should be made aware that overwatering of slopes is detrimental to
slope stability.
J3 MAINTENANCE
J3.1 Periodic inspections of landscaped slope areas should be planned and appropriate
measures should be taken to control weeds and enhance growth of the landscape
plants. Some areas may require occasional replanting and/or reseeding.
J3.2 Terrace drains and downdrains should be periodically inspected and maintained free
of debris. Damage to drainage improvements should be repaired immediately.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 23
J3.3 Property owners should be made aware that burrowing animals can be detrimental to
slope stability. A preventative program should be established to control burrowing
animals.
J3.4 As a precautionary measure, plastic sheeting should be readily available, or kept on
hand, to protect all slope areas from saturation by periods of heavy or prolonged
rainfall. This measure is strongly recommended, beginning with the period of time
prior to landscape planting.
J4 REPAIRS
J4.1 If slope failures occur, the Geotechnical Consultant should be contacted for a field
review of site conditions and development of recommendations for evaluation and
repair.
J4.2 If slope failures occur as a result of exposure to periods of heavy rainfall, the failure
area and currently unaffected areas should be covered with plastic sheeting to
protect against additional saturation.
J4.3 In the accompanying Standard Details, appropriate repair procedures are illustrated
for superficial slope failures (i.e., occurring typically within the outer one foot to three
feet of a slope face).
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 24
K. TRENCH BACKFILL
K1 Utility trench backfill should, unless otherwise recommended, be compacted by mechanical
means. Unless otherwise recommended, the degree of compaction should be a minimum of
90 percent of the laboratory maximum density.
K2 As an alternative, granular material (sand equivalent greater than 30) may be thoroughly
jetted in-place. Jetting should only be considered to apply to trenches no greater than two
feet in width and four feet in depth. Following jetting operations, trench backfill should be
thoroughly mechanically compacted and/or wheel rolled from the surface.
K3 Backfill of exterior and interior trenches extending below a 1:1 projection from the outer edge
of foundations should be mechanically compacted to a minimum of 90 percent of the
laboratory maximum density.
K4 Within slab areas, but outside the influence of foundations, trenches up to one foot wide and
two feet deep may be backfilled with sand and consolidated by jetting, flooding or by
mechanical means. If on-site materials are utilized, they should be wheel-rolled, tamped or
otherwise compacted to a firm condition. For minor interior trenches, density testing may be
deleted or spot testing may be elected if deemed necessary, based on review of backfill
operations during construction.
K5 If utility contractors indicate that it is undesirable to use compaction equipment in close
proximity to a buried-conduit, the Contractor may elect the utilization of light weight
mechanical compaction equipment and/or shading of the conduit with clean, granular
material, which should be thoroughly jetted in-place above the conduit, prior to initiating
mechanical compaction procedures. Other methods of utility trench compaction may also be
appropriate, upon review by the Geotechnical Consultant at the time of-construction.
K6 In cases where clean granular materials are proposed for use in lieu of native materials or
where flooding or jetting is proposed, the procedures should be considered subject to review
by the Geotechnical Consultant.
K7 Clean granular backfill and/or bedding are not recommended in slope areas unless
provisions are made for a drainage system to mitigate the potential build-up of seepage
forces.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 25
L STATUS OF GRADING
Prior to proceeding with any grading operation, the Geotechnical Consultant should be notified at
least two working days in advance in order to schedule the necessary observation and testing
services.
L1 Prior to any significant expansion or cut back in the grading operation, the Geotechnical
Consultant should be provided with adequate notice (i.e., two days) in order to make
appropriate adjustments in observation and testing services.
L2 Following completion of grading operations and/or between phases of a grading operation,
the Geotechnical Consultant should be provided with at least two working days notice in
advance of commencement of additional grading operations.
Geofabric
Minimum
15% open
area;
EOS = 40 - 70
1ft. min. overlap.
24"
min.
Nominal 2-3"
24"
min.
Geof abric Alternative
Geofabric Alternative
Backhoe Trench
Dozer Trench
Filter Material
9ft. / ft.3
24"
min.
12" min.
3
, , etc. or 1 "
open graded
rock; 6 ft. /ft.
38 12 12 Filter
material - 9ft. /ft.3
6" min.*
12" min.
**
CANYON SUBDRAIN
Drains along canyon walls
as recommended by the
geotechnical consultant.
Install as - needed per
buttress backdrain detail.
Removal ofunsuitablematerial
Proposed Grading
Bedrock
Bench:Vertical 4ft. min.
Horizontal 6ft. min.Canyon
Subdrain
Compacted FillNatu
r
a
l
G
r
o
u
n
d
Notes:
1- Pipe be 4" min. diameter, 6" min. for runs of 500ft to 1000ft, 8" min. for runs of 1000ft. or greater.
2- Pipe should be schedule 40 PVC or similiar. Upstream ends should be capped.
3- Pipe should have 8 uniformly spaced 3/8" perforations per foot placed at 90 oset on underside
of pipe. FInal 20 foot of pipe should be nonperforated.
4- Filter material should be Calif. Class 2 Permeable Material.
5- Appropriate gradient should be provided for drainage; 2% minimum is recommended.
6- For the Geofabric Alternatives and gradients of 4% or greater, pipe may be omitted from the upper
500ft. For runs of 500, 1000, and 1500ft or greater 4", 6", and 8" pipe, respectively, should be provided.
o
Nominal 2-3"
Separation
6" min.
STANDARD DETAIL NO. 1
H/2 or 15ft min
H/2 or 15ft min
HRecontour, slope
to drain or
provide paved
drainage swales
and down drains
Fill Slo
p
e
Fill Slo
p
e
Remove uns
u
i
t
a
b
l
e
m
a
t
e
r
i
a
l
Remove
u
n
s
u
i
t
a
b
l
e
m
a
t
e
r
i
a
l
H
Backcut not steeper
than 1:1
Backcut not steeper
than 1:1
1 - If overfilling and cutting back to
grade is adopted, 15ft. min. fill
width may be reduced to 12ft. min.
In no case should the fill
width be less than 1/2 the
height of fill remaining.
2 - Backdrain as recommended by
geotechnical consultant per
buttress backdrain detail.
Bench: Vertical 4ft min.
Horizontal 6ft min.
Bench: Vertical 4ft min.
Horizontal 6ft min.
Notes:
STANDARD DETAIL NO. 2
cut slope
FILL OVER NATURAL SLOPE
slope
Natural
FILL OVER CUT SLOPE2 ft. min.
key depth at toe;
tip key 1ft. nominal
or 4% into slope
*
*
*
Backcut 1:1 max.
maintain 15ft. min. width
Fill Slope 2:1
or flatter
Dt
Compacted
Fill
3ft. min. cap
HFill Slope 2:1
or flatter (1)
Compacted
Fill
Backcut 1:1 max.
maintain 15ft. min.
fill width
15ft.
min.
H/2 or 15ft.
min.
Bench: Vertical 4 ft. min.
Horizontal 6 ft. min.
Backdrain system if
recommended by geotechnical
consultant.3 ft. min.2 ft. min.
H
3ft. min. cap (2)
STABILIZATION FILL
BUTTRESS FILL
W
Dh
Bench: Vertical 4ft. min.
Horizontal 6ft. min.
Backdrain System per
Standard Details
15ft.
min.
Bedding planes or other
adverse geological
condition.
- If overfilling and cutting back to grade is adopted,
15ft. may be reduced to 12ft. In no case should
the fill width be less than 1/2 the fill height remaining.
- A 3ft. blanket fill shall be provided above stabilization
and buttress fills. The thickness may be greater as
recommended by the geotechnical consultant.
- W = designed width of key.
- Dt = designed depth of key at toe
- Dh = depth of key at heel; unless
otherwise specified, Dh = Dt + 1ft.
Notes:
STANDARD DETAIL NO. 3
2
1
34 5
2
1
3
4
5
Conventional Backdrain
STABILIZATION FILL
STANDARD DETAIL NO. 4
3ft.
nominal
4in. min.
3ft.
nominal
H
4%
2 ft. nominal
1ft. nominal 12.5 ft. nominal
interval *
* For H 18 ft.
additional upper
drain may be
omitted.
<_
Horizontal spacing of
outlets should be
limited to about
100 ft.
Geofrabic Alternative
Geofabric: Minimum
15% open area
EOS = 40 - 70; 1ft.
min. overlap.
See details below
Blanket Fill, 3ft. min.
Notes:
1 - Pipe should be 4 inch diameter
Schedule 40 PVC or similiar.
2 - Gradients should be 4% or greater.
3 - Cap all upstream ends
4 - Trenches for outlet pipes
should be backfilled with
compacted native soil.
5 - Backdrain pipe should have
8 uniformly spaced perforations
per foot placed 90 offset on
underside of pipe. Outlet pipe should
be nonperforated.
6 - For the geofrabric alternative the
backdrain pipe may be omitted
provided at least 20 feet (i.e. 10 ft
each side of outlet) of perforated
pipe is provided to lead into
each outlet.
7 - At each outlet the geofabric
should be appropriately overlapped
(1ft.) at cuts in fabric or otherwise
sealed or taped around the pipe.
o
2ft. min.
4in. min.
2ft. min.
Clean, open graded rock; pea gravel
3/8, 1/2, 3/4 or 1-inch; 3ft /ft. min.3
Calif. Class 2 Permeable
material 3ft 3/ft. min.
View Along Canyon
Proposed Future Grade
FUTURE CANYON FILL
STANDARD DETAIL NO. 5
View of Canyon Sidewall
Future limit of
engineered fill
Future limit of
engineered fill
Future Benching
Natur
al grade
up ca
n
y on
Bedro
c
k
Futur
e
r
e
m
o
v al of
unsui
t
a
b
le ma
t
e
r
ial
Survey end of subdrainsubdrain trench
Bedrock
Proposed Future Grade
Future
Removal
Current limit of
engineered fill
Tempory Grade to Provide Drainage Natur al g r ade
up can y on
Future extension
of subdr ain
Unsuitable
material (e.g.
alluvium, topsoil,
colluvium)
Bedrock
Existing
Engineered Fill
Existing
Engineered Fill
1
1 1
1
1 1
TRANSITION LOT OVER-EXCAVATION
STANDARD DETAIL NO. 6
Cut Lot
Cut-Fill Lot
Or iginal Gr ade
Fir m Natur al Groun
d
per grading
plan
Removal, of topsoil,
colluvium, weathered
bedrock
Engineered
Fill
per grading
plan.
Engineered Fill pergrading plan.
Overexcavate and replace asengineered fill.6 inch. min. scarificationin place and recompaction
Finished Grade
Bench: Vertical 4ft. min. Horizontal 6ft. min.
Removal ofunsuitable
materials
6 inch. min. scarificationin place and recompaction
Finished Grade
3ft. min.
Overexcavate and replace asengineered fill.
Bench: Vertical 4ft. min. Horizontal 6ft. min.
5ft.
min.
Or iginal Gr
ade
Fir m Natur al Grou
n
d
1 - Topsoil, colluvium, weathered bedrock and otherwise unsuitable materials
should be removed to firm natural ground as identified by the geotechnical
consultant.
2 - The minimum depth of overexcavation should be considered subject to review
by the geotechnical consultant. Steeper transitions may require deeper
overexcavation.
3 - The lateral extent of overexcavation should be 5 feet minimum, but may
include the entire lot as recommended by the geotechnical consultant.
4 - The contractor should notify the geotechnical consultant in advance of
achieving final grades (i.e. within 5 ft.) in order to evaluate overexcavation
recommendations. Additional staking may be requested to aid in the
evaluation of overexcavations.
Notes:
5ft.
min.
ROCK DISPOSAL
STANDARD DETAIL NO. 7
Windrow Section
Windrow Profile
Fill Slope
Place
m
e
n
t
Limit
o
f
r
o
c
k
Utility
Finished Grade
Stagger Locations
of rock windrows
20ft. nominal spacing
Bedrock or Firm Natural Ground
Fill surface during grading
Fill surface during grading
Compacted Fill
Rock should be placed end to end.
Rock should not be nested.
5ft. Vertical Separation
3ft. min.
10ft.
10ft.
20ft.
Dozer V-ditch or fill thoroughly
compacted to a smooth unyielding
condition (e.g. by wheel rolling.)
Place rock on 3 to 6 inches granular
as recommended for flooding *
1 - Following placement of rock, flooding of granular material, and
placement of compacted fill adjacent to windrow, each windrow
should be thoroughly compacted from the surface.
2 - The contractor should provide to the geotechnical consultant plans
prepared by survey documenting the location of buried rock.
3 - Disposal in streets may be subject to more restrictive
requirements by the governing authorities.
Notes:
3ft. max.20ft. nominal spacing
* clean grandular material
(S.E. 30) should be
thoroughly flooded to
fill voids around rock.
>_
MINOR SLOPE REPAIR STANDARD DETAIL NO. 8
Tensar CE3 Erosion Control Grid
pinned on slope face; 4ft. each way;
Gr id of 12in. min. galvanized anchor pins
Keep chimney
drains 2 - 3ft.
below grade.
Slope
4 M Tensar SS-2 geog rid at 2ft.
vertical spacing; tip at 10%
roll out along slope to
provide continuous layers.
Chimney drain system
30ft. O.C.
Typical backdrain: 12.5ft. max.
vertical spacing; tip out of slope
at 4%; place at as low an elevation
as possible to allow for outletting.
Existing firm natural ground
or compacted fill
2ft. min.
key depth
Soil slump
1ft. min.
Bench 4ft.+_
Key width
controlled
by geogrid
(14ft. )+_
2
1
3
4
5
1
3
2Overfill slope and
cut back to compacted
core exposing edge
of geogrid.
*
*
MINOR SLOPE REPAIR STANDARD DETAIL NO. 8A
Tensar CE3 Erosion Control Grid
pinned on slope face; 4ft. each way;
Grid of 12in. min. galvanized anchor pins
Keep geofabric
drains 2 - 3ft.
below grade.
Slope
4 M Tensar SS-2 geogrid at 2ft.
vertical spacing; tip at 10%
roll out along slope to
provide continuous layers.
Geofabric drainagesystem, 15ft. o.c.
Typical backdrain: place at as low anelevation as possible to allow for
outletting through curb.
Existing firm natural ground
or compacted fill
2ft. min.
key depth
Soil slump
1ft. min.
Bench 4ft.+_
Key width
2
1
3
4
5
1
3
2Overfill slope and
cut back to compacted
core exposing edge
of geogrid.
*
*
LOT DRAINAGE
2%
2%
2%
2%
2%
2%
2%
2%
2%
2%
2%
Alternative A
Gutters and downspouts
to yard drains where
roof sections slope
to side yards.
Yard drains at 1% or greater
4 inch minimum pvc pipe
or similiar to suitable
disposal area (e.g. curb outlet.)
1 - Drainage into swale areas should be at 2% gradient.
Directly away from buildings drainage should be at 5%.
Notes:
STANDARD DETAIL NO. 9