1999-6113 GNoText
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GEOTECHNICAL EXPLORATION, INC.
SOIL & FOUNDATION ENGINEERING. GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT. ENGINEERING GEOLOGY
29 September 1 998
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Windsor LL C
6027 Firwood Row
La Jolla, CA 92037
Attn: Mr. Hamid Kazerouni
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Job No. 98-7343
Subject:
Plan Review Comments
Parcel 3
1 243 Windsor Road
Encinitas, California
Dear Mr. Kazerouni:
As requested, and as required by the City of Encinitas plan checklist dated August
20, 1998, we are herein addressing the pertinent items.
BACKGROUND INFORMATION
Our firm explored the soils on the subject site, which includes three lots.
The
findings, conclusions and recommendations of that soil exploration were presented
in our "Report of Soil Investigation...," dated August 20, 1998, Job No. 98-7343.
In our soils report we recommended that at least the upper 3 to 3 Y:z feet of on-site
soils be excavated, mixed with soils of lower expansion potential, moisture
conditioned at a moisture content higher than the optimum, and recompacted. In
addition, we recommended that the continuous and isolated foundations be
embedded at least 1 5 inches into properly prepared ground.
The allowable soil
bearing capacity for soils prepared in a proper manner (as described in the soils
report) and for footings embedded at least 1 5 inches below lowest adjacent grade
7420 TRADE STREET. SAN DIEGO, CALIFORNIA 92121 . (619) 549-7222 . FAX: (619) 549-1604
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REPORT OF SOIL INVESTIGATION
3-Lot Residential Development
1243 Windsor Road
Encinitas, California
JOB NO. 98-7343
20 August 1998
Prepared for:
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Mr. Hamid Kazerouni
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~~~~D GEOTECHNICAL EXPLORATION, INC.
D SOIL & FOUNDATION ENGINEERING. GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT. ENGINEERING GEOLOGY
20 August 1998
WINDSOR LLC
6027 Firwood Row
La Jolla, CA 92037
Attn: Mr. Hamid Kazerouni
Job No. 98-7343
Subject:
Report of Soil Investigation
3-Lot Residential Development
1 243 Windsor Road
Encinitas, California
Dear Mr.Kazerouni:
In accordance with your request and our proposal of July 16, 1998, Geotechnical
Exploration, Inc. has performed an investigation of the soil conditions at the
location of the proposed 3-lot residential project at the subject vacant lot sites. The
field work was performed on August 10, 1998.
It is our understanding that new pre-manufactured single-family residential
structures will be erected at the 3-lot site. The new structures will be of standard-
type building materials, utilizing slab-on-grade floors, and continuous concrete
perimeter foundations.
Our investigation revealed that the site is underlain by 1 foot of poor quality, loose
sandy topsoil overlying 2 to 3 feet of expansive sandy clay topsoil of varying
density overlying silty, clayey and fine to medium sand terrace soils. The
formational terrace soils have good-bearing strength characteristics, are of very low
expansion potential and are suitable for support of the proposed new structures.
The encountered topsoils are of poor quality and they are not suitable for Support of
the new homes in their existing condition. These topsoils will need to be excavated
and recompacted to be utilized as support of the new foundations. If clayey
topsoils are encountered at a higher expansion potential than those encountered
during our investigation, foundations and slabs will require additional size and
reinforcement.
7420 TRADE STREET. SAN DIEGO, CALIFORNIA 92121 . (619) 549-7222 . FAX: (619) 549-1604
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In our opinion, if the conclusions and recommendations presented in this report are
implemented during site preparation, the site will be suited for the proposed new
improvements.
This opportunity to be of service is sincerely appreciated. Should you have any
questions concerning the following report, please do not hesitate to contact us.
Reference to our Job No. 98-7343 will expedite response to your inquiries.
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Respectfully submitted,
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GEOTECHNICAL EXPLORATION, INC.
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Jaime A. Cerros, P.E.
R.C.E. 34422/G.E. 2007
Senior Geotechnical Engineer
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TABLE OF CONTENTS
PAGE
I. SCOPE OF WORK
II. SITE DESCRIPTION
III. FIELD INVESTIGATION
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IV. DESCRIPTION OF SOILS
, V. GROUNDWATER
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VI. LA80RA TORY TESTS AND SOIL INFORMATION
VII. CONCLUSIONS AND RECOMMENDATIONS
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V/IL GRADING NOTES
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IX.
LIMITATIONS
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FIGURES
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I. Plot Plan
lIa-c. Exploratory Logs
/II. Laboratory Soil Data
IV. Consolidation-Pressure Curve
APPENDICES
A.
8.
Unified Soil Classification System
General Earthwork Specifications
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REPORT OF SOIL INVESTIGATION
Proposed 3-Lot Residential Development
1 243 Windsor Road
Encinitas, California
JOB NO. 98-7343
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The following report presents the findings and recommendations of Geotechnical
Exploration, Inc. for the subject project.
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I. SCOPE OF WORK
It is our understanding, based on communications with Mr. Hamid Kazerouni, that
the vacant 3-lot site will be developed with three pre-manufactured single-family
homes.
Continuous concrete perimeter footings and slab-on-grade garage floors
will be used. At the time of preparation of this report, no plans were available for
our review.
With the above in mind, the Scope of Work is briefly outlined as follows:
1 .
Identify and classify the surface and subsurface soils to depths, in confor-
mance with the Unified Soil Classification System (refer to Appendix A).
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2.
Recommend site preparation procedures.
3.
Recommend the allowable bearing capacity and wall active and passive
pressures for the existing soils.
4.
Estimate the anticipated settlement of the on-site soils under any new
proposed structural loads.
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3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 2
The scope of this investigation did not include geologic and seismic studies for the
site. Additionally, our work was limited to where access allowed.
II. SITE DESCRIPTION
The property is known as: Assessor's Parcel Nos. 260-191-44, 260-191-45, and
260-191-46, per Parcel Map No.1 0441, in the City of Encinitas, County of San
Diego, State of California.
The site is located just north of and adjacent to 1261 Windsor Road, in the City of
Encinitas. The 3-lot property is currently undeveloped (i.e., vacant). The property
is bordered on the south, north and east by developed single-family residential lots,
and on the west by Windsor Road (a city street). Freestanding masonry walls exist
along or near the east property line on top of a small slope which rises from the
subject vacant lot.
An asphaltic concrete (AC) driveway bounds the southern
property line.
This driveway provides access to several single-family homes,
including a flag lot, south of the subject sites.
Vegetation on the site consists primarily of dried grass, several mature eucalyptus
trees on the south property line, and a thick growth of large shrubs on the north
property line.
The property slopes down gently to the west from the rear (east) portion of the lot
and is 3 to 4 feet higher than Windsor Road.
Survey information concerning actual elevations across the subject lots was not
available at the time of this investigation.
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3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 3
III. FIELD INVESTIGATION
Three exploratory trenches were placed across the lot where access allowed, one in
each parcel. The trenches were logged by our field representative, and samples
were taken of the predominant soils throughout the field operation. Excavation logs
have been prepared on the basis of our observations, and the results have been
summarized on Figure No. II.
The predominant soils have been classified in
conformance with the Unified Soil Classification System (refer to Appendix A).
Bulk and in-place soil samples were obtained.
IV. DESCRIPTION OF SOILS
In general, the subject site is underlain by formational soils overlain by varying
thicknesses of topsoils.
These materials were encountered in all our exploratory
trenches. Minor thicknesses of fill may exist along the south property line near the
asphalt-paved driveway and on or near the east property line where a small slope
supports the freestanding masonry walls.
TODSOi/: These materials were encountered in all of our exploratory trenches. The
encountered topsoils ranged in thickness from 3 to 3 Yz feet. They consist of an
upper orange-brown to gray-brown, silty sand up to 1 foot thick over a 2- to 2 Yz-
foot thick sandy clay sand which grades downward into silty clayey and fine to
medium sand. They range in consistency from loose (where primarily silty sand) to
stiff (clayey soil). The silty materials have marginal bearing strength characteristics
which may vary across the site and the clay topsoils have a low to medium
potential expansion index. Refer to Figure Nos. I, II, and III.
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3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 4
Terrace Soils:
These soils were encountered in all of our exploratory trenches.
They are overlain by topsoils. The encountered terrace soils consist of gray-brown
to light brown silty sand, fine to medium sand, and silty clayey sand. These soils
have good bearing-strength characteristics and have a very low potential expansion
index. Refer to Figure Nos. I, II, and III for details regarding these soils.
V. GROUNDWATER
No groundwater was encountered during the course of our relatively shallow field
investigation and we do not expect groundwater problems to develop in the future -
if the property is developed with proper drainage and that proper drainage is
maintained on the property.
It should be kept in mind, however, that any required grading operations may
change surface drainage patterns andlor reduce permeabilities due to the
densification of compacted soils.
Such changes of surface and subsurface
hydrologic conditions, plus irrigation of landscaping or significant increases in
rainfall, may result in the appearance of minor amounts of surface or near-surface
water at locations where none existed previously. The damage from such water is
in general, expected to be minor and cosmetic in nature, if good positive drainage is
implemented at the completion of construction. Corrective action should be taken
on a site-specific basis if, and when, it becomes necessary.
VI. LABORATORY TESTS AND SOIL INFORMATION
Laboratory tests were performed on the disturbed and relatively undisturbed soil
samples in order to evaluate their physical and mechanical properties and their
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 5 .
ability to support the proposed deck structures.
conducted on the sampled soils:
The following tests were
1. Moisture/Density Relations (ASTM D1557-91, Method A)
2. Expansion Test (UBC Standard 29-C)
3. Mechanical Analysis (ASTM 0422-90)
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The relationship between the moisture and density of undisturbed soil samples
gives qualitative information regarding soil strength characteristics and present soil
conditions.
Based on our experience and laboratory testing, the on-site terrace sands in general
have a very low expansion potential, with an Expansion Index (EI) of 10 per UBC
Table 29-C. The tested on-site clay topsoil materials have an EI of 46.
Based upon the above laboratory test data, observations of the primary soil types
on the project, and our previous experience with laboratory testing of similar soils,
our Geotechnical Engineer has utilized conservative values for friction angle and
cohesion to those terrace soils which will have significant lateral support or bearing
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functions on the project.
These values have been utilized in recommending the
allowable bearing value as well as the active and passive earth pressures for wall
and footing designs.
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The Mechanical Analysis Test was used to aid in the classification of the soils
according to the Unified'Soil Classification System.
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Encinitas, California
Job No. 98-7343
Page 6
VII. CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations are based upon the field
investigation conducted by our firm (and resulting laboratory tests), in conjunction
with our knowledge and experience with the soils in this area of the City of
Encinitas.
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Our investigation revealed that the proposed single-family residential sites are
underlain by 3 to 3 Y:z feet of variable quality silty sand and clay topsoils. These
soils are underlain by medium dense sand terrace materials. We recommend that
the clay topsoils be excavated, mixed with soils of lower expansive potential,
moisture conditioned, and ,ecompacted. Final elevations planned for the project þ:
should take thi.S. .'..equ. ired fill. removal into account. Should grading be li~ite~ to a (
~inimum, th,~proposed foundations should penetrate at least 1 foot into the v-..
terrace material.
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A.
Preparation of Soils for Site Development (Utilizing Conventional Grading
Methods)
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Existing site topsoils shall be removed in the building pad area prior to the
preparation of the building pads andlor areas to receive structural or rigid
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improvements. We recommend the clay topsoil be mixed with soils of lower
expansion potential, moisture-conditioned, and be properly recompacted.
To provide a more uniform, firm soil base for the proposed structure and
associated improvements, the final grade natural terrace soils shall be
scarified at least 6 inches and moisture conditioned up to at least 5 feet
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 7
outside the limits of the new structure area (when feasible), as per
indications of our field technician.
On-site soils and any imported fill soils (if utilized) shall be watered to at least
4 percent above Optimum Moisture content, and compacted to at least 90
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percent of Maximum Dry Density (MDD). Areas to receive new fill or that
will support rigid improvements or proposed retaining structures should be
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prepared in a like manner with all newly placed fill soils compacted to a
minimum of 90 percent of MDD.
Some topsoils and fill soils may be
encountered in unexplored areas during the grading operation. As such, the
exposed soils should be observed and proof-rolled with heavy equipment to
disclose areas with soft soils or tested by our field technician.
If
encountered, these areas will require removal and recompaction and shall be
prepared as previously described for new fill soils.
All on-site soils with
medium expansion potential shall be compacted with a moisture content at
least 4 percent above the optimum.
3.
No uncontrolled fill soils shall remain on the site after completion of any
future site work. In the event that temporary ramps or pads are constructed
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of uncontrolled fill soils during the grading operation, the loose fill soils shall
be removed andlor recompacted prior to completion of the grading operation.
4.
Any buried objects or particular soft soil areas which might be discovered on
the site shall be removed and the excavation shall be properly backfilled with
approved on-site or imported fill soils. If imported soils are used, they shall
be low-expansive and shall then be compacted to at least 90 percent of
Maximum Dry Density.
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
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5.
Any backfill soils placed in utility trenches or behind retaining walls which
support structures and other improvements (such as patios, sidewalks,
driveways, pavements, etc.) shall be compacted to at least 90 percent of
Maximum Dry Density for low expansive soils.
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B.
Design Parameters for Foundations and R.,taining Wall!¡
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6.
The recommended allowable soU bearing value for design of foundations for
the proposed new structure is 2,000 pounds per square foot (psf).
This
allowable soil bearing capacity may be utilized in the design of continuous
foundations and spread footings when founded a minimum of 15 inches into
the properly prepared natural materials or properly compacted fill, measured
from the lowest adjacent grade at the time of foundation construction and a
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width of at least one foot. An additional 500 psf may be allowed for every
additional foot in width and 800 psf for every foot in depth below 1 5 inches
for the basic allowable bearing capacity, not to exceed 4,500 psf. This
vertical allowable soil bearing capacity may be further increased one-third for
design. analysis that include wind or seismic loads. If imported soils are
required to bring the site to grade, the imported soils should be low
expansive and be obtained from an approved off-site borrow area (E.!. less
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than 50).
Based upon our laboratory test results and our experience with the soil types
on the subject site, the underlying formational materials and all properly
compacted fill should experience a total settlement of less than 1 inch and a
differential settlement in the magnitude of approximately 3/4-inch, under a
3-Lot Residential Development
Encinitas, California
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Job No. 98-7343
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structural load within the allowable bearing capacity. The angular rotation
due to differential settlement is anticipated to be less than 1/300.
Due to numerous reasons, footings and slabs occasionally crack. Footings
and slabs should therefore contain at least a nominal amount of reinforcing
steel to reduce the separation width of cracks, should they occur.
A minimum of steel for continuous footings up to 1 5 inches deep
should include at least four No.5 steel bars continuous, with two bars
3 inches from the bottom of the footing and two bars near the top.
More steel would be required for larger footings. Reinforcing shall be
provided per the structural engineer's drawings.
Isolated square footings should contain, as a minimum, a grid of No.4
steel bars on 12-inch centers, in both directions, with no less than
three bars each way.
Garage floor slabs on-grade should be a minimum of 4 inches actual
thickness and be reinforced with at least No.3 steel bars on 15-inch
centers, in both directions, placed at midheight in the slab.
~ A 4-inch (minimum) base layer shaJl be provided under any new slabs
of the driveway and garage to help provide a uniform surface on which
to place the fresh concrete.
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Areas with raised wood floors (if utilized) shall be provided with either
isolated piers embedded not less than 1 5 inches into the graded,
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 10
properly compacted soils or with continuous footings similarly
embedded into the compacted soils. Surface piers shall not be used.
Perimeter walls shall be supported by continuous foundations, also
embedded at least 15 inches into properly compacted soil.
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We recommend the project Civil/Structural Engineer incorporate
isolation joints and sawcuts to at least one-fourth the thickness of the
slab in any floor designs. The joints and cuts, if properly placed,
should reduce the potential for and help control floor slab cracking. In
no case, however, shall control joints be spaced farther than 20 feet
apart. Re-entrant corners shall also be provided with control joints or
additional steel reinforcing. Due to a number of reasons (such as base
preparation, construction techniques, curing procedures, and normal
shrinkage of concrete), some cracking of slabs can still be expected.
Control joints shall be placed within 12 hours after concrete
placement. For large slabs, the reinforcing shall have every other bar
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interrupted at control joints for an effective weak plane result.
To
prevent moisture infiltration, all exterior slab joints shall be sealed with
elastomeric seal material.
The sealant shall be inspected every six
months and be properly maintained.
Furthermore, the slabs may be
designed
with
sufficient
steel
reinforcement
and
shrinkage
compensating concrete so that no joints are required.
NOTE: The project Civil/Structural Engineer shall review all reinforcing
schedules. The reinforcing minimums recommended herein are not to
be construed as structural designs, but primarily as minimum
safeguards to reduce possible crack separations. The actual
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3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 11
reinforcing schedule shall be as per the direction of the Civil/Structural
Engineer.
8.
As a minimum for protection of on-site improvements, it is recommended
that all non-structural, non-vehicular concrete slabs (such as patios,
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walkways, etc.) be underlain by properly compacted on-site soil, include 6x6-
6/6 welded wire mesh at midheight of the slab, and contain adequate
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isolation and control joints. The isolation joints and control joints shall be
provided with a flexible joint filler which should be periodically inspected and
be properly maintained. Spacing of control joints shall be 15 feet or the
width of the slab, whichever is less. Furthermore, control joints shall be
placed at re-entrant corners.
Improvements such as adjacent sidewalks
should be provided with a drainage slope of at least 2 percent. It should be
noted that standard concrete improvements may not perform well on the
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existing loose surface soils, slab cracking under such conditions should be
anticipated. As such, each improvement should be designed to tolerate the
on-site conditions, or if a higher risk for damage is not acceptable to the
owner, the subgrade soils up to a depth of 2 feet (as a minimum) should be
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removed and recompacted. The performance of on-site improvements can
also be greatly affected by soil base preparation and the quality of
construction, and is therefore the responsibility of the designer and the
contractor installing the improvements.
We recommend that the slab and
footing subgrade soils be checked for proper moisture and compaction by our
representative within 48 hours prior to concrete pouring.
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Job No. 98-7343
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c.
Retaining Walls
9.
The active earth pressure (to be utilized in the design of any cantilever walls,
allowed to rotate) shall be based on an EquiValent "ufdWeight of 38 pounds
per cubic foot (for level backfill only and low to non-expansive imported
soils). For walls with sloping backfill, the equivalent fluid active weight is 62
pcf for 2.0: 1.0 slopes, and 70 pcf for 1.5: 1.0 slopes.
In the event that a new retaining wall is to be designed for a restrained
condition (such as basement walls), a uniform pr,ssure equal to 9xH (nine
times the total height of retained wall, considered in pounds per square foot)
shall be considered as acting everywhere on the back of the walt in addition
to the design Equivalent Fluid Weight. Any other surcharge loads applied
within a horizontal distance measured from the face of the wall equal to its
height shall be considered in the structural design.
The passive earth pressure of the encountered medium dense, natural-ground
soils and any recompacted fill soils (to be used for design of shallow
foundations and footings to resist the lateral forces) shall be based on an
Equivalent Fluid Weight of 276 pounds per cubic foot. This passive earth
pressure shall only be considered valid for design if the ground adjacent to
the foundation structure is essentially level for a distance of at least three
times the total depth of the foundation and is properly compacted or dense
native soil.
A Coefficient of Friction of 0.40 times the dead load may be used between
the bearing soils and concrete foundations, walls, or floor slabs.
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Encinitas, California
Job No. 98-7343
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D.
Site Drainage Considerations
12.
Adequate measures shall be taken to properly finish-grade the site after the
new structure and other improvements are in place. Drainage waters from
this site and adjacent properties are to be directed away from foundations,
floor slabs, footings, and slopes, onto the natural drainage direction for this
area or into properly designed and approved drainage facilities. Roof gutters
and downspouts should be installed on the structure, with runoff directed
away from the foundations via closed drainage lines. Proper subsurface and
surface drainage will help reduce the potential for waters to seek the level of
the bearing soils under the foundations, footings, and floor slabs. Failure to
observe this recommendation could result in undermining, uplifting and
differential settlement of the structure of other improvements on the site.
Currently, the Uniform Building Code requires a minimum 2 percent surface
gradient for proper drainage of building pads, unless waived by the building
official. Concrete pavement may have a minimum gradient of 0.5 percent.
In addition, appropriate erosion-control measures shall be taken at all time
during construction to prevent surface runoff waters from entering footing
excavations and ponding on finished building pads or pavement areas.
Due to the possible buildup of groundwater (derived primarily from rainfall
and irrigation), excess moisture is a common problem in below-grade
structures or behind retaining walls. These problems are generally in the
form of water seepage through walls, mineral staining, mold growth and high
humidity. In order to reduce the potential for moisture-related problems to
develop at the site, proper ventilation and waterproofing shall be provided for
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 1 4
below-ground areas and the backfill side of all accessible, exposed structure
retaining walls should be properly waterproofed and drained.
A layer of
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Miradrain 6000 or J-drain layer, plus protective board, and a subdrain system
plus waterproofing shall be placed for building retaining walls. Crawl space
perimeter walls (if utilized) shall also be waterproofed and drained if they act
as building retaining walls.
Furthermore, proper and sufficient cross
ventilation shall be provided to crawl spaces.
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Retaining walls (if utilized) shall be provided with waterproofing and a
subdrain system at the bottom of the wall. The subdrain shall consist of a
perforated Schedule 40 PVC pipe or SDR35, placed in an envelope of
crushed rock smaller than 1-inch in diameter, and be wrapped with geofabric
such as Mirafi 140N or equivalent. The subdrain bottom shall be placed at
least 1 foot below the bottom of the slab-on-grade or soil surface being
protected. The subdrain shall outlet in an approved drainage facility or into a
sump pump pit.
14.
Planter areas, flower beds, and planter boxes shall be sloped to drain away
from the foundations, footings, and floor slabs. Planter boxes shall be
constructed with a closed bottom and a subsurface drain, installed in gravel,
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with the direction of subsurface and surface flow away from the
foundations, footings, and floor slabs, to an adequate drainage facility.
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Any planter areas adjacent to the building or surrounded by concrete
improvements shall be provided with sufficient area drains to help for quick
runoff disposal. No water shall be allowed to pond adjacent to the building
or other improvements.
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Encinitas, California
Job No. 98-7343
Page 1 5
E.
General Recommendations
15.
Where not superseded by specific recommendations presented in this report,
trenches, excavations, drilled holes, and temporary slopes at the subject site
shall be constructed in accordance with Title 8, Construction Safety Orders,
issued by OSHA. This office should be contacted for additional recommen-
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dations if shoring is required. For basement level walls, the temporary cuts
can be made at a slope ratio of at least 3/4 horizontal to 1 vertical. Removal
of adjacent fences and/or extension of the excavations may require
permission from adjacent neighbors. Shoring may be required, depending on
the extent of excavations and the neighbors cooperation to construction of
this project.
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16.
In order to reduce any work delays at the subject site during site
development, this firm should be contacted 24 hours prior to any need for
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observation of footing excavations or field density testing of compacted fill
soils. Placement of formwork and steel reinforcement in footing excavations
should not occur prior to our observation of the excavations; in the event
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that our observations reveal the need for deepening or redesigning foundation
structures at any locations, any formwork or steel reinforcement in the
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affected footing excavation areas would have to be removed prior to
correction of the observed problem (i.e., deepening the footing excavation,
recompacting soil in the bottom of the excavation, etc.).
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Job No. 98-7343
Page 1 6
VIII. GRADING NOTES
Any required grading operations shall be performed in accordance with the General
Earthwork Specifications (Appendix B) and the requirements of the City of Encinitas
Grading Ordinance.
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17.
Geotechnical Exploration, Inc. recommends that we be asked to verify the
actual soil conditions revealed during site grading work and footing
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excavations to be as anticipated in this "Report of Soil Investigation."
In
addition, the compaction of any fill soils placed during site grading work
must be tested. It is the responsibility of the grading contractor to comply
with the requirements on the grading plans and the local grading ordinance.
18.
It is the responsibility of the owner and/or developer to ensure that the
recommendations summarized in the report are carried out in the field
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operations and that our recommendations for design of the project are
incorporated in the building and grading plans. It is recommended that we
review the grading and foundation plans prior to construction operations to
verify that our recommendations are incorporated in the plans, and to verify
that any additional or modified recommendations that are warranted are
included in the plans.
19.
This firm does not practice or consult in the field of safety engineering. We
do not direct the contractor's operations, and we cannot be responsible for
the safety of personnel other than our own on the site; the safety of others
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is the responsibility of the contractor.
The contractor should notify the
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3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 1 7
owner if he considers any of the recommended actions presented herein to
be unsafe.
IX. LIMITATIONS
Our conclusions and recommendations have been based upon all available data
obtained from our field investigation and laboratory analysis, as well as our
experience with the soils and native materials located in this area of the City of
Encinitas. Of necessity, we must assume a certain degree of continuity between
exploratory excavations andlor natural exposures. It is, therefore, necessary that
all observations, conclusions, and recommendations be verified at the time grading
operations begin or when footing excavations are placed. In the event
discrepancies are noted, additional recommendations may be issued, if required.
The work performed and recommendations presented herein are the result of an
investigation and analysis which meet the contemporary standard of care in our
profession within the County of San Diego.
This report should be considered valid for a period of two (2) years, and is subject
to review by our firm following that time. If significant modifications are made to
the building andlor grading plans, especially with respect to the height and location
of the proposed structure, this report must be presented to us for immediate review
and possible revision.
The firm of Geotechnical Exploration, Inc. shall not be held responsible for changes
to the physical condition of the property, such as addition of fill soils or changing
3-Lot Residential Development
Encinitas, California
Job No. 98-7343
Page 1 8
drainage patterns, which occur subsequent to issuance of this report, or any work
done without our observations and testing.
This opportunity to be of service is sincerely appreciated.
Should you have any
l
questions, please feel free to contact our office. Reference to our Job No. 98-7343
will help expedite a reply to your inquiries.
! ~-
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
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Donald C. Vaugh
Project Coordina r
Jaime A. Cerros, P.E.
R.C.E. 34422/G.E. 2007
Senior Geotechnical Engineer
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NOTE: This Plot Plan is not to be used for legal
purposes. Locations and dimensions are approxi-
mate. Actual property dimensions and locations
of utilities may be obtained from the Approved
Building Plans or the "As-Built" Grading Plans.
REFERENCE: This Plot Plan was prepared
from an existing San Diega County Assessor's
Parcel Map provided by the client and fram
on-site field reconnaissance preformed by GEl.
PLOT PLAN
WINDSOR 3 LOT
RESIDENTIAL DEVELPMENT
1243 WINDSOR ROAD
ENCINITAS, GA.
JOB NUMBER 98-7343
f~&ii GEOiECHNICAL
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TEST P IT LOG
JOB NAME
LOCATION
Windsor 3-Lot De\
1243 Windsor Roac
Encinitas. CA
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DIMENSION AND
TYPE OF EXCAVATION
0
9' X 4t' X 2' Trench
2
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GEOTECHNICAL
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PARTICLE-SIZE ANAL YSIS OF SOILS
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NO. DEPTH
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Encinitas. CA
DIMENSION AND
ìYPE OF EXCAVATION
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JOB NUMBER 98-7343 EXPlORATION INC.
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JOB NUMBER 98-7341
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Site Terrace
Materia1s
RING DIAMETER 2.375 (inches)
FIGURE NUMBER III c
JOB NUMBER 98-7343
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APPENDIX A
UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION
COARSE-GRAINED
More than half of material la larger than a No. 200 sieve
GRAVELS, CLEAN GRAVELS
More than half of coarse fraction is larger than GW Well-graded gravels, gravel and sand mix-
No.4 sieve size. but smaller than 3" tures. little or no fines.
GP Poorly graded gravels, gravel and sand mix-
tures, little or no fines,
GRAVELS WITH FINES
(appreciable amount)
GM Silty gravels. poorly graded gravel-sand-silt
mixtures,
GC Clay gravels. poorly graded gravel-sand-silt
mixtures,
SANDS, CLEAN SANDS SW Well-graded sand, gravelly sands. little or no
More than half of coarse fraction is smaller than a no fines,
No.4 sieve.
SP Poorly graded sands. gravelly sands, little or
no fines.
SANDS WITH FINES
(appreciable amount)
SM Silty sands, poorly graded sand and silty
mixtures.
SC Clayey sands, poorly graded sand and clay
mixtures.
FINE-GRAINED
More than half of material la smaller than a No. 200 sieve
SILTS AND CLAYS
ML Inorganic silts and very fine sands. rock flour,
sandy silt and clayey-silt sand mixtures with
a slight plasticity,
CL Inorganic clays of low to medium plasticity,
gravelly clays, sandy clays, silty clays, clean
clays.
Liquid Limit Less Than 50
OL Organic silts and organic silty clays of low
plasticity.
Liquid Limit Greater Than 50,
MH Inorganic silts, micaceous or diatomaceous
fine sandy or silty soils. elastic silts'.
CH Inorganic clays of high plasticity. fat clays.
OH Organic clays of medium to high plasticity.
HIGHLY ORGANIC SOilS
PT
Peat and other highly organic soils.
APPENDIX B
GENERAL EARTHWORK SPECIFICATIONS
General
The objective of these specifications is to properly establish procedures for the clearing and preparat
of the existing natural ground or properly compacted fill to receive new fill; for the selection of the
material; and for the fill compaction and testing methods to be used.
Scope of Work
The earthwork includes all the aetivities and resources provided by the contractor to construct in a go
workmanlike manner all the grades of the filled areas shown in the plans. The major items of we
covered in this section include all clearing and grubbing, removing and disposing of materials, prepari.
areas to be filled, compacting of fill, compacting of backfills, subdrain installations, and all other we
necessary to complete the grading of the filled areas.
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Site Visit and Site InvestigatioQ
1. The contractor shall visit the site and carefully study it, and make all inspections necessary
order to determine the full extent of the work required to complete all grading in conformance wi-
the drawings and specifications. The contractor shall satisfy himself as to the nature, locatioi
and extent of the work conditions, the conformation and condition of the existing ground surfacf
and the type of equipment, labor, and facilities needed prior to and during prosecution of the worl
The contractor shall satisfy himself as to the character, quality, and quantity of surface an
subsurface materials or obstacles to be encountered. Any inaccuracies or discrepancies betwee
the actual field conditions and the drawings, or between the drawings and specifications, must b
brought to the engineer's attention in order to clarify the exact nature of the work to b
performed.
2.
A soils investigation report has been prepared for this project by GEL It is available for review anc
should be used as a reference to the surface and subsurface soil and bedrock conditions on thi~
project. Any recommendations made in the report of the soil investigation or subsequent report~
shall become an addendum to these specifications.
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Authority of the Soils Engineer and Engineering Geologist
The soils engineer shall be the owner's representative to observe and test the construction of fills.
Excavation and the placing of fill shall be under the observation of the seils engineer and his/her
representative, and he/she shall give a written opinion regarding conformance with the specifications
upon completion of grading. The soils engineer shall have the authority to cause the removal and
replacement of porous topsoils, uncompacted or improperly compacted fills, disturbed bedrock materials,
and soft alluvium, and shall have the authority to approve or reject materials proposed for use in the
compacted fill areas,
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The soils engineer shall have, in conjunction with the engineering geologist, the authority to approve the
preparation of natural ground and toe-of-fill benches to receive fill material. The engineering geologist
shall have the authority to evaluate the stability of the existing or proposed slopes, and to evaluate the
necessity of remedial measures: If any unstable condition is being created by cutting or filling, the
engineering geologist and/or soils engineer shall advise the contractor and owner immediately, and
prohibit grading in the affected area until such time as corrective measures are taken.
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1. After preparing the areas"to be filled, the approved fill material shall be placed in approximately
horizontal layers, with lift thickness compatible to the material being placed and the type of
J equipment being used. Uniess otherwise approved bV the soils engineer, each laver spread for
compaction shall not exceed 8 inches of loose thickness. Adequate drainage of the fill shall be
provided at all times during the construction period.
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9.
83
Fill and Backfill Material
Unless otherwise specified, the on-site material obtained from the project excavations may be used as f
or backfill, provided that all organic material, rubbish, debris, and other objectionable material containe
therein is first removed. In the event that expansive materials are encountered during foundatic
excavations within 3 feet of finished grade and they have not been properly processed, they shall t:
entirely removed or thoroughly mixed with good, granular material before incorporating them in fills. N
footing shall be allowed to bear on soils which, in the opinion of the soils engineer, are detrimentall
expansive -- unless designed for this clayey condition.
However, rocks, boulders, broken Portland cement concrete, and bituminous-type pavement obtainec
from the project excavations may be permitted in the backfill or fill with the following limitations:
1.
The maximum dimension of any piece used in the top 10 feet shall be no larger than 6 inches.
2
Clods or hard lumps of earth of 6 inches in greatest dimension shall be broken up befon
compacting the material in fill.
3.
If the fill material originating from the project excavation contains large rocks, boulders, or hare
lumps that cannot be broken readily, pieces ranging from 6 inches in diameter to 2 feet ir
maximum dimension may be used in fills below final subgrade if all pieces are placed in such ê
manner (such as windrows) as to eliminate nesting or voids between them. No rocks over 4 feet
will be allowed in the fill.
4.
Pieces larger than 6 inches shall not be placed within 12 inches of any structure.
5.
Pieces larger than 3 inches shall not be placed within 12 inches of the subgrade for paving.
Rockfills containing less than 40 percent of soil passing 3/4-inch sieve may be permitted in
designated areas. Specific recommendations shall be made by the soils engineer and be subject to
approval by the city engineer. .
Continuous observation by the soils engineer is required during rock placement.
Special and/or additional recommendations may be provided in writing by the soils engineer to
modify, clarify, or amplify these specifications.
During grading operations, soil types other than those analyzed in the soil investigation report may
be encountered by the contractor. The soils engineer shall be consulted to evaluate the suitability
of these soils as fill materials.
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2.
When the moisture content of the fill material is below that specified by the engineer, water sh
be added to it until the moisture content is as specified.
3.
When the moisture content of the fill material is above that specified by the engineer, resulting
inadequate compaction or unstable fill, the fill material shall be aerated by blading and scarifying
other satisfactory methods until the moisture content is as specified.
4.
After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted:
not less than the density set forth in the specifications. Compaction shall be accomplished wit
sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other approved types of acceptabi
compaction equipment. Equipment shall be of such design that it will be able to compact the f;
to the specified relative compaction. Compaction shall cover the entire fill area, and th
equipment shall make sufficient trips to ensure that the desired density has been obtainer
throughout the entire fill. At locations where it would be impractical due to inaccessibility c
rolling compacting equipment, fill layers shall be compacted to the specified requirements by hanG
directed compaction equipment.
5.
When soil types or combination of soil types are encountered which tend to develop denseh
packed surfaces as a result of spreading or compacting operations, the surface of each layer of fil
shall be sufficiently roughened after compaction to ensure bond to the succeeding layer.
6.
Unless otherwise specified, fill slopes shall not be steeper than 2.0 horizontal to 1.0 vertical. Ir
general, fill slopes shall be finished in conformance with the lines and grades shown on the plans.
The surface of fill slopes shall be overfilled to a distance from finished slopes such that it wil
allow compaction equipment to operate freely within the zone of the finished slope, and then cut
back to the finished grade to expose the compacted core. Alternate compaction procedures
include the backrolling of slopes with sheepsfoot rollers in increments of 3 to 5 feet in elevation
gain. Alternate methods may be used by the contractor, but they shall be evaluated for approval
by the soils engineer.
Unless otherwise specified, all allowed expansive fill material shall be compacted to a moisture
content of approximately 2 to 4 percent above the optimum moisture content. Nonexpansive fill
shall be compacted at near-optimum moisture content. All fill shall be compacted, unless
otherwise specified, to a relative compaction not less than 95 percent for fill in the upper 12
inches of subgrades under areas to be paved with asphalt concrete or Portland concrete, and not
less than 90 percent for other fill. The relative compaction is the ratio of the dry unit weight of
the compacted fill to the laboratory maximum dry unit weight of a sample of the same soil,
obtained in accordance with A.S.T.M. 0-1557 test method.
The observation and periodic testing by the soils engineer are intended to provide the contractor
with an ongoing measure of the quality of the fill compaction operation. It is the responsibility of
the grading contractor to, utilize this information to establish the degrees of compactive effort
required on the project. More importantly, it is the responsibility of the grading contractor to
ensure that proper compactive effort is applied at all times during the grading operation, including
during the absence of soils engineering representatives.
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Trench Backfill
1. Trench excavations which extend under graded lots, paved areas, areas under the influence t
structural loading, in slopes or close to slope areas, shall be backfilled under the observations ar
testing of the soils engineer. All trenches not falling within the aforementioned locations shall t
backfilled in accordance with the City or County regulating agency specifications.
2.
Unless otherwise specified, the minimum degree of compaction shall be 90 percent of th
laboratory maximum dry density.
3.
Any soft, spongy, unstable, or other similar material encountered in the trench excavation upo'
which the bedding material or pipe is to be placed, shall be removed to a depth recommended b'
the soils engineer and replaced with bedding materials suitably densified.
Bedding material shall first be placed so that the pipe is supported for the full length of the barre
with full bearing on the bottom segment. After the needed testing of the pipe is accomplished
the bedding shall be completed to at least 1 foot on top of the pipe. The bedding shall be properl~
densified before backfill is placed. Bedding shall consist of granular material with a sane
equivalent not less than 30, or other material approved by the engineer.
4.
No rocks greater than 6 inches in diameter will be allowed in the backfill placed between 1 foot
above the pipe and 1 foot below finished subgrade. Rocks greater than 2.5 inches in anv
dimension will not be allowed in the backfill placed within 1 foot of pavement subgrade.
5.
Material for mechanically compacted backfill shall be placed in lifts of horizontal layers and
properly moistened prior to compaction. In addition, the layers shall have a thickness compatible
with the material being placed and the type of equipment being used. Each layer shall be evenly
spread, moistened or dried, and then tamped or rolled until the specified relative compaction has
been attained.
Backfill shall be mechanically compacted by means of tamping rollers, sheepsfoot rollers,
pneumatic tire rollers, vibratory rollers, or other mechanical tampers. Impact-type pavement
breakers (stompers) will not be permitted over clay, asbestos cement, plastic, cast iron, or
nonreinforced concrete pipe. Permission to use specific compaction equipment shall not be
construed as guaranteeing or implying that the use of such equipment will not result in damage to
adjacent ground, existing improvements, or improvements installed under the contract. The
contractor shall make his/her own determination in this regard.
Jetting shall not be permitted as a compaction method unless the soils engineer allows it in
writing.
Clean granular material shall not be used as backfill or bedding in trenches located in slope areas
or within a distance of 1.0 feet of the top of slopes unless provisions are made for a drainage
system to mitigate the potential buildup of seepage forces into the slope mass.
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Observations and Testing
1 . The soils engineers or their representatives shall sufficiently observe and test the gradin
operations so that they can state their opinion as to whether or not the fill was constructed i
accordance with the specifications.
2.
The soils engineers or their representatives shall take sufficient density tests during the placemer
of compacted fill. The contractor should assist the soils engineer and/or his/her representative b'
digging test pits for removal determinations and/or for testing compacted fill. In addition, th
contractor should cooperate with the soils engineer by removing or shutting down equipment fro IT
the area being tested.
3.
Fill shall be tested for compliance with the recommended relative compaction and moisturE
conditions. Field density testing should be performed by using approved methods by A.S.T.M.
such as A.S.T.M. 01556, 02922, and/or 02937. Tests to evaluate density of compacted fil
should be provided on the basis of not less than one test for each 2-foot vertical lift of the fill, bu:
not less than one test for each 1,000 cubic yards of fill placed. Actual test intervals may vary as
field conditions dictate. In fill slopes, approximately half of the tests shall be made at the fil:
slope, except that not more than one test needs to be made for each 50 horizontal feet of slope if,
each 2-foot vertical lift. Actual test intervals 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 soils engineer.
Site Protection
It shall be the grading contractor's obligation to take all measures deemed necessary during grading to
maintain adequate safety measures and working conditions, and to provide erosion-control devices for
the protection of excavated areas, slope areas, finished work on the site and adjoining properties, from
storm damage and flood hazard originating on the project. It shall be the contractor's responsibility to
maintain slopes in their as-graded form until all slopes are in satisfactory compliance with the job
specifications, all berms and benches have been properly constructed, and all associated drainage devices
have been installed and meet the requirements of the specifications.
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All observations, testing services, and approvals given by the soils engineer andlor geologist shall not
relieve the contractor of his/her responsibilities of performing the work in accordance with these
specifications.
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After grading is completed and the soils engineer has finished his/her observations and/or testing of the
work, no further excavation or filling shall be done except under his/her observations.
Adverse Weather Conditions
1 . Precautions shall be taken by the contractor during the performance of site clearing, excavations,
and grading to protect the worksite from flooding, ponding, or inundation by poor or improper
surface drainage. Temporary provisions shall be made during the rainy season to adequately direct
surface drainage away from and off the worksite. Where low areas cannot be avoided, pumps
should be kept on hand to continually remove water during periods of rainfall.
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