HomeMy WebLinkAboutX2014-1817 - SoilsNorCal Engineering
Soils and Geotechnical Consultants
10641 Humbolt Street Los Alamitos, CA 90720
(562) 799-9469 Fax (562) 799-9459
August 9, 2016
Gary Edwards
c/o Western Realco
500 Newport Center Drive, Suite 630
Newport Beach, California 92660
)(206 4 A17
S 62 9 50(15d ,40 0 Dr
Project Number 17201-13
RE: Report of Geotechnical Observation and Testing of Rough Grading
and Backfill Operations - Proposed Residential Development - Located
at 3621 Sausalito Drive, Corona del Mar, in the City of Newport Beach,
California
Dear Mr. Edwards:
Pursuant to your request, this firm has provided this geotechnical report to summarize
the observation and testing performed during rough grading and backfill operations at
the above referenced project. The geotechnical aspects were conducted in accordance
with our report titled "Geotechnical Investigation", dated January 21, 2014, Project
Number 17201-13. Our geotechnical services pertaining to the grading of the project
development are summarized in the subsequent sections of this report.
Site Gradina
The purpose of)the grading and backfill operations was to provide structural support of
the proposed development. All vegetation and demolition debris was stripped and
removed. The upper low density surface soils were removed to competent native soils.
The exposed surface was scarified, moisture conditioned and then recompacted to a
minimum of 90% relative compaction. Fill soils placed in the ground fllor areas east and
west of the basement were compacted to a minimum 90% of the laboratory standard in
lifts not in excess of eight inches in thickness. The maximum depth of fill soils placed
was approximately 3'/z feet.
August 9, 2016 Project Number 17201-13
Page 2
Wall Backfill
A drain system was installed behind the basement retaining walls. The drain consisted
of 4 -inch diameter perforated PVC pipe and % inch gravel wrapped with filter fabric.
The gravel was capped with approximately two feet of compacted fill soils. Backfill soils
placed beyond the gravel zone were compacted to a minimum of 90% relative
compaction with a maximum depth of approximately 9 feet. Additional gravel was
placed north and south of the basement. The gravel was overlain with filter fabric and
capped with approximately 1'/z feet of fill soils.
Hand operated compaction equipment was utilized for compaction control. A water
hose provided moisture control. Our services did not include any surveying of
excavation bottoms, building corners, or subgrade elevations during grading operations.
Laboratory/Field Testina
The relative compaction was determined by Sand Cone Method (ASTM: D1556-07) and
by the Drive Tube Method (ASTM: D 2937-10). The maximum density of the on-site
soils was obtained by the laboratory standard (ASTM: D1557-12) and results are shown
on Table I. Tests were performed a minimum of every 500 cubic yards placed and
every two feet in depth of fill placed. A summary of the compaction tests of the rough
grading operations are described in Appendix B with locations shown on the
accompanying plan.
A. Expansion index tests in accordance with ASTM D 4829-11 were performed on
remolded samples of the upper soils to determine the expansive characteristics
and to provide any necessary recommendations for reinforcement of the slabs -
on -grade and the foundations. Results of these tests are provided on Table II in
Appendix A.
B. Soluble sulfate tests in accordance with California Test Method 417 were
performed on representative soils samples to estimate the potential for corrosion
of concrete in contact with the on-site soils. Results are provided on Table III in
Appendix A.
NorCal Engineering
August 9, 2016
Page 3
Project Number 17201-13
Foundation Design
Foundations for new structures may be designed utilizing an allowable soil bearing
capacity of 1,800 psf for a minimum embedded depth of 24 inches below lowest
adjacent grade into compacted fill. A minimum of 3 feet of recently placed compacted
fill soils shall underlie all new house foundations. A one-third increase may be used
when considering short term loading from wind and seismic forces. Foundations near
top of slope shall be embedded to maintain a horizontal slope setback distance equal to
or greater than 1/3 the overall height of slope.
All continuous foundations shall be reinforced with a minimum of two #5 bars, top and
two bottom. Additional reinforcement due to soil expansion or proposed loadings may
be necessary and shall be determined by the project engineers and/or architect. A
representative of this firm shall observe all foundation excavations prior to pouring
concrete.
Slab Design
Concrete floor slabs -on -grade and any exterior slabs shall be a minimum of 5 inches in
thickness and reinforced with #4 bars at 16 inch spacing, each way, positioned in the
center of the slab. An effective plasticity index of 25 should also be used in slab design.
Soils beneath all exterior and interior slabs shall be brought to approximately 3% above
optimum levels to a depth of 18 inches as verified by the soil engineer prior to
placement of concrete.
Additional reinforcement requirements and an increase in thickness of the slabs -on -
grade may be necessary based upon soils expansion potential and proposed loading
conditions in the structures and should be evaluated further by the project engineers
and/or architect. Design of exterior slabs should take into consideration the information
contained in the attached Expansive Soils Guidelines.
NorCal Engineering
August 9, 2016 Project Number 17201-13
Page 4
A vapor retarder should be utilized in areas which would be sensitive to the infiltration of
moisture. This retarder shall meet requirements of ASTM E 96, Water Vapor
Transmission of Materials and ASTM E 1745, Standard Specification for Water Vapor
Retarders used in Contact with Soil or Granular Fill Under Concrete Slabs. The vapor
retarder shall be installed in accordance with procedures stated in ASTM E 1643,
Standard practice for Installation of Water Vapor Retarders used in Contact with Earth
or Granular Fill Under Concrete Slabs.
The moisture retarder may be placed directly upon 4 inches of compacted granular,
non -expansive soils and overlain with 1 inch of sand placed in a dry condition. The
moisture retarder is required only in interior floor slab areas or beneath slabs where the
infiltration of moisture is deemed undesirable.
Expansive Soil
The upper on-site soils have a moderate expansion potential. When soils are
expansive, special attention should be given to the project design and maintenance.
The attached Expansive Soil Guidelines should be reviewed by the engineers,
architects, owner, maintenance personnel and other interested parties and considered
during the design of the project and future property maintenance.
Corrosion Design Criteria
Representative samples of the surficial soils revealed negligible sulfate concentrations.
Therefore, all concrete in contact with on site soils shall be designed in accordance with
Table 4.3.1 of ACI 318 Building Code and Commentary. Sulfate test results may be
found on the attached Table III.
Limitations
It should be noted that our work does not warrant or guarantee that the contractor
responsible for each phase of the project has performed his work in accordance with the
project specifications.
NorCal Engineering
August 9, 2016 Project Number 17201-13
Page 5
We appreciate this opportunity to be of service to you. If you have any further
questions, please do not hesitate to contact the undersigned.
Respectfully submitted, ,---: ,
NORCAL ENGINEERING ,i�la JI" rcc Cly
r Lr 1,41
�L C�
Keith D. Tucker is
Project Engineer `A� c A
R.G.E. 841
NorCal Engineering
Walter K. Mott
Project Manager
August 9, 2016
Page 6
Expansive Soil Guidelines
Project Number 17201-13
The following expansive soil guidelines are provided for your project. The intent of
these guidelines is to inform you, the client, of the importance of proper design and
maintenance of projects supported on expansive soils. You, as the owner or other
interested party, should be warned that you have a duty to provide the
information contained in the soil report including these guidelines to your design
engineers, architects, landscapers and other design parties in order to enable
them to provide a design that takes into consideration expansive soils.
In addition, you should provide the soil report with these guidelines to any property
manager, lessee, property purchaser or other interested party that will have or assume
the responsibility of maintaining the development in the future.
Expansive soils are fine-grained silts and clays which are subject to swelling and
contracting. The amount of this swelling and contracting is subject to the amount of
fine-grained clay materials present in the soils and the amount of moisture either
introduced or extracted from the soils. Expansive soils are divided into five categories
ranging from "very loud' to "very high". Expansion indices are assigned to each
classification. If the expansion index of the soils on your site, is 21 or higher, you have
expansive soils. The classifications of expansive soils are as follows:
Classification of Expansive Soil*
Expansion Index
Potential Expansion
0-20
Very Low
21-50
Low
51-90
Medium
91-130
High
Above 130
Very High
"From Table 18A -1-B of California Building Code (1988)
When expansive soils are compacted during site grading operations, care is taken to
place the materials at or slightly above optimum moisture levels and perform proper
compaction operations. Any subsequent excessive wetting and/or drying of expansive
soils will cause the soil materials to expand and/or contract. These actions are likely to
cause distress of foundations, structures, slabs -on -grade, sidewalks and pavement over
the life of the structure. It is therefore imperative that even after construction of
improvements, the moisture contents are maintained at relatively constant levels,
allowing neither excessive wetting or drying of soils.
NorCal Engineering
August 9, 2016 Project Number 17201-13
Page 7
Evidence of excessive wetting of expansive soils may be seen in concrete slabs, both
interior and exterior. Slabs may lift at construction joints producing a trip hazard or may
crack from the pressure of soil expansion. Wet clays in foundation areas may result in
lifting of the structure causing difficulty in the opening and closing of doors and windows,
as well as cracking in exterior and interior wall surfaces. In extreme wetting of soils to
depth, settlement of the structure may eventually result. Excessive wetting of soils in
landscape areas adjacent to concrete or asphaltic pavement areas may also result in
expansion of soils beneath pavement and resultant distress to the pavement surface.
Excessive drying of expansive soils is initially evidenced by cracking in the surface of
the soils due to contraction. Settlement of structures and on -grade slabs may also
eventually result along with problems in the operation of doors and windows.
Projects located in areas of expansive clay soils will be subject to more movement and
"hairline" cracking of walls and slabs than similar projects situated on non -expansive
sandy soils. There are, however, measures that developers and property owners may
take to reduce the amount of movement over the life the development. The following
guidelines are provided to assist you in both design and maintenance of projects on
expansive soils:
• Drainage away from structures and pavement is essential to prevent
excessive wetting of expansive soils. Grades of at least 3% should be
designed and maintained to allow flow of irrigation and rain water to
approved drainage devices or to the street. Any "ponding" of water adjacent
to buildings, slabs and pavement after rains is evidence of poor drainage; the
installation of drainage devices or regrading of the area may be required to
assure proper drainage. Installation of rain gutters is also recommended to
control the introduction of moisture next to buildings. Gutters should
discharge into a drainage device or onto pavement which drains to roadways.
• Irrigation should be strictly controlled around building foundations, slabs and
pavement and may need to be adjusted depending upon season. This
control is essential to maintain a relatively uniform moisture content in the
expansive soils and to prevent swelling and contracting. Over -watering
adjacent to improvements may result in damage to those improvements.
NorCal Engineering makes no specific recommendations regarding
landscape irrigation schedules.
• Planting schemes for landscaping around structures and pavement should
be analyzed carefully. Plants (including sod) requiring high amounts of water
may result in excessive wetting of soils. Trees and large shrubs may actually
extract moisture from the expansive soils, thus causing contraction of the
fine-grained soils.
NorCal Engineering
August 9, 2016
Page 8
Project Number 17201-13
Thickened edges on exterior slabs will assist in keeping excessive moisture
from entering directly beneath the concrete. A six-inch thick or greater
deepened edge on slabs may be considered. Underlying interior and exterior
slabs with 6 to 12 inches or more of non -expansive soils and providing
presaturation of the underlying clayey soils as recommended in the soil
report will improve the overall performance of on -grade slabs.
Increase the amount of steel reinforcing in concrete slabs, foundations and
other structures to resist the forces of expansive soils. The precise amount
of reinforcing should be determined by the appropriate design engineers
and/or architects.
Recommendations of the soil report should always be followed in the
development of the project. Any recommendations regarding presaturation
of the upper subgrade soils in slab areas should be performed in the field
and verified by the Soil Engineer.
NorCal Engineering
APPENDICES
(In order of appearance)
Appendix A — Laboratory Tests
Table I — Maximum Density Tests
Table 11— Expansion Index
Table III - Sulfate Tests
Appendix B — Summary of Compaction Tests
Site Plan
Summary of Compaction Tests
NorCal Engineering
Appendix A
NorCal Engineering
August 9, 2016 Project Number 17201-13
Page 9
TABLE
MAXIMUM DENSITY TESTS
(ASTM: D1557-12)
Optimum Maximum Dry
Sample Classification Moisture Density (lbs./cum
I Clayey sandy SILT 12.5 116.0
II Clayey sandy SILT 13.5 114.5
TABLE II
EXPANSION INDEX TESTS
(U.B.C. STD. 4829-11)
Expansion
Sample Classification Index
Pad Subgrade Clayey sandy SILT 58
TABLE III
SULFATE TESTS
Sample
Pad Subgrade
Sulfate (% by Weight)
0.010
NorCal Engineering
Appendix B
NorCal Engineering
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r August 9, 2016 Project Number 17201-13
Page 10
**Retest of failing tests after area reworked
S= Sand Cone Method
D= Drive Tube Method
NorCal Engineering
SUMMARY OF COMPACTION TEST RESULTS
Date of
Test
Percent
Unit Wt.
Relative
Soil Test
Test
No.
Location
Depth
Moisture
lbs./cu.ft.
Compaction
Type S/D
6/1/16
101
Slab Subgrade
0.0-0.5
14.1
105.8
91
1 D
6/3/16
102
Slab Subgrade
0.0-0.5
14.4
108.9
94
1 S
6/23/16
103
Wall Backfill
4.0-4.5
13.9
107.5
93
1 D
6/23/16
104
Wall Backfill
3.0-3.5
13.4
105.6
91
1 D
6/24/16
105
Wall Backfill
1.0-1.5
13.1
107.8
93
I D
6/27/16
106
Wall Backfill
1.0-1.5
14.5
106.6
93
II S
6/27/16
107
Wall Backfill
1.0-1.5
13.2
105.4
91
1 D
6/28/16
108
Wall Backfill
0.0-0.5
12.7
106.4
92
1
7/1/16
109
Wall Backfill
0.5-1.0
12.2
104.6
91
If S
7/1/16
110
Wall Backfill
7.0-7.5
12.5
106.7
92
1 D
7/1/16
111
Wall Backfill
5.0-5.5
12.2
106.4
92
1 D
7/5/16
112
Wall Backfill
3.0-3.5
11.4
109.5
94
1 D
7/6/16
113
Wall Backfill
1.0-1.5
11.0
105.2
91
1 S
' 7/6/16
114
Wall Backfill
0.0-0.5
11.2
107.0
92
1 D
7/6/16
115
Wall Backfill
0.0-0.5
11.6
108.4
93
1 D
7/7/16
116
Site Grading
3.5-4.0
12.4
107.7
94
11 D
7/8/16
117
Site Grading
1.5-2.0
12.2
108.3
93
1 S
7/8/16
118
Site Grading
0.0-0.5
11.8
107.0
92
1 D
7/8/16
119
Site Grading
0.0-0.5
11.6
108.4
93
1 D
7/11/16
120
Site Grading
3.0-3.5
12.2
105.2
91
1 D
7/11/16
121
Site Grading
1.0-1.5
11.9
105.3
94
II S
7/11/16
122
Site Grading
0.0-0.5
11.5
108.3
93
1 D
8/5/16
123
Garage Slab
0.0-0.5
14.0
105.3
91
1 D
**Retest of failing tests after area reworked
S= Sand Cone Method
D= Drive Tube Method
NorCal Engineering
NorCal Engineering
Soils and Geotechnical Consultants
10641 Humbolt Street Los Alamitos, CA 90720
(562) 799-9469 Fax (562) 799-9459
August 17, 2018
Gary Edwards
c/o Western Realco
500 Newport Center Drive, Suite 630
Newport Beach, California 92660
Project Number 17201-13
RE: Geotechnical Grading Report - Proposed Residential Development -
Located at 3621 Sausalito Drive, Corona del Mar, in the City of Newport
Beach, California
Dear Mr. Edwards:
Pursuant to your request, this firm has provided this geotechnical report to summarize
the observation and testing performed during rough grading and backfill operations at
the above referenced project. The geotechnical aspects were conducted in accordance
with our report titled "Geotechnical Investigation", dated January 21, 2014, Project
Number 17201-13. Our geotechnical services pertaining to the grading of the project
development are summarized in the subsequent sections of this report.
Site Grading
The purpose of the grading and backfill operations was to provide structural support of
the proposed development. All vegetation and demolition debris was stripped and
removed. The upper low density surface soils were removed to competent native soils.
The exposed surface was scarified, moisture conditioned and then recompacted to a
minimum of 90% relative compaction. Fill soils placed in the ground fllor areas east and
west of the basement were compacted to a minimum 90% of the laboratory standard in
lifts not in excess of eight inches in thickness. The maximum depth of fill soils placed
was approximately 3'/2 feet.
August 17, 2018 Project Number 17201-13
Page 2
Wall Backfill
A drain system was installed behind the basement retaining walls. The drain consisted
of 4 -inch diameter perforated PVC pipe and % inch gravel wrapped with filter fabric.
The gravel was capped with approximately two feet of compacted fill soils. Backfill soils
placed beyond the gravel zone were compacted to a minimum of 90% relative
compaction with a maximum depth of approximately 9 feet. Additional gravel was
placed north and south of the basement. The gravel was overlain with filter fabric and
capped with approximately 1'/2 feet of fill soils.
Hand operated compaction equipment was utilized for compaction control. A water
hose provided moisture control. Our services did not include any surveying of
excavation bottoms, building corners, or subgrade elevations during grading operations.
Laboratory/Field Testing
The relative compaction was determined by Sand Cone Method (ASTM: D1556-07) and
by the Drive Tube Method (ASTM: D 2937-10). The maximum density of the on-site
soils was obtained by the laboratory standard (ASTM: D1557-12) and results are shown
on Table I. Tests were performed a minimum of every 500 cubic yards placed and
every two feet in depth of fill placed. A summary of the compaction tests of the rough
grading operations are described in Appendix B with locations shown on the
accompanying plan.
A. Expansion index tests in accordance with ASTM D 4829-11 were performed on
remolded samples of the upper soils to determine the expansive characteristics
and to provide any necessary recommendations for reinforcement of the slabs -
on -grade and the foundations. Results of these tests are provided on Table II in
Appendix A.
B. Soluble sulfate tests in accordance with California Test Method 417 were
performed on representative soils samples to estimate the potential for corrosion
of concrete in contact with the on-site soils. Results are provided on Table III in
Appendix A.
NorCal Engineering
August 17, 2018 Project Number 17201-13
Page 3
Foundation Design
Foundations for new structures may be designed utilizing an allowable soil bearing
capacity of 1,800 psf for a minimum embedded depth of 24 inches below lowest
adjacent grade into compacted fill. A minimum of 3 feet of recently placed compacted
fill soils shall underlie all new house foundations. A one-third increase may be used
when considering short term loading from wind and seismic forces. Foundations near
top of slope shall be embedded to maintain a horizontal slope setback distance equal to
or greater than 1/3 the overall height of slope.
All continuous foundations shall be reinforced with a minimum of two #5 bars, top and
two bottom. Additional reinforcement due to soil expansion or proposed loadings may
be necessary and shall be determined by the project engineers and/or architect. A
representative of this firm shall observe all foundation excavations prior to pouring
concrete.
In addition, foundation excavations observed and approved by a representative of this
firm prior to pouring concrete were embedded into competent bearing material.
Slab Design
Concrete floor slabs -on -grade and any exterior slabs shall be a minimum of 5 inches in
thickness and reinforced with #4 bars at 16 inch spacing, each way, positioned in the
center of the slab. An effective plasticity index of 25 should also be used in slab design.
Soils beneath all exterior and interior slabs shall be brought to approximately 3% above
optimum levels to a depth of 18 inches as verified by the soil engineer prior to
placement of concrete.
Additional reinforcement requirements and an increase in thickness of the slabs -on -
grade may be necessary based upon soils expansion potential and proposed loading
conditions in the structures and should be evaluated further by the project engineers
and/or architect. Design of exterior slabs should take into consideration the information
contained in the attached Expansive Soils Guidelines.
NorCal Engineering
August 17, 2018 Project Number 17201-13
Page 4
A vapor retarder should be utilized in areas which would be sensitive to the infiltration of
moisture. This retarder shall meet requirements of ASTM E 96, Water Vapor
Transmission of Materials and ASTM E 1745, Standard Specification for Water Vapor
Retarders used in Contact with Soil or Granular Fill Under Concrete Slabs. The vapor
retarder shall be installed in accordance with procedures stated in ASTM E 1643,
Standard practice for Installation of Water Vapor Retarders used in Contact with Earth
or Granular Fill Under Concrete Slabs.
The moisture retarder may be placed directly upon 4 inches of compacted granular,
non -expansive soils and overlain with 1 inch of sand placed in a dry condition. The
moisture retarder is required only in interior floor slab areas or beneath slabs where the
infiltration of moisture is deemed undesirable.
Drain Line Trench
Backfill soils placed within the drain line trench along the north side of the property were
compacted to a minimum of 90% relative compaction. Hand operated equipment was
utilized for compaction control. The approximate location of this trench is shown on the
attached plan.
Expansive Soil
The upper on-site soils have a moderate expansion potential. When soils are
expansive, special attention should be given to the project design and maintenance.
The attached Expansive Soil Guidelines should be reviewed by the engineers,
architects, owner, maintenance personnel and other interested parties and considered
during the design of the project and future property maintenance.
Corrosion Desian Criteria
Representative samples of the surficial soils revealed negligible sulfate concentrations.
Therefore, all concrete in contact with on site soils shall be designed in accordance with
Table 4.3.1 of ACI 318 Building Code and Commentary. Sulfate test results may be
found on the attached Table III.
NorCal Engineering
August 17, 2018
Page 5
Project Number 17201-13
Limitations
It should be noted that our work does not warrant or guarantee that the contractor
responsible for each phase of the project has performed his work in accordance with the
project specifications.
We appreciate this opportunity to be of service to you. If you have any further
questions, please do not hesitate to contact the undersigned.
Respectfully submitted,
NORCAL ENGINEERING
Keith D. Tucker
Project Engineer
R.G.E. 841
NorCal Engineering
Michael A. Barone
Project Manager
August 17, 2018
Page 6
Expansive Soil Guidelines
Project Number 17201-13
The following expansive soil guidelines are provided for your project. The intent of
these guidelines is to inform you, the client, of the importance of proper design and
maintenance of projects supported on expansive soils. You, as the owner or other
interested party, should be warned that you have a duty to provide the
information contained in the soil report including these guidelines to your design
engineers, architects, landscapers and other design parties in order to enable
them to provide a design that takes into consideration expansive soils.
In addition, you should provide the soil report with these guidelines to any property
manager, lessee, property purchaser or other interested party that will have or assume
the responsibility of maintaining the development in the future.
Expansive soils are fine-grained silts and clays which are subject to swelling and
contracting. The amount of this swelling and contracting is subject to the amount of
fine-grained clay materials present in the soils and the amount of moisture either
introduced or extracted from the soils. Expansive soils are divided into five categories
ranging from "very low" to "very high". Expansion indices are assigned to each
classification. If the expansion index of the soils on your site, is 21 or higher, you have
expansive soils. The classifications of expansive soils are as follows:
Classification of Expansive Soil*
Expansion Index
Potential Expansion
0-20
Very Low
21-50
Low
51-90
Medium
91-130
High
Above 130
Very High
*From Table 18A -1-B of California Building code (196ts)
When expansive soils are compacted during site grading operations, care is taken to
place the materials at or slightly above optimum moisture levels and perform proper
compaction operations. Any subsequent excessive wetting and/or drying of expansive
soils will cause the soil materials to expand and/or contract. These actions are likely to
cause distress of foundations, structures, slabs -on -grade, sidewalks and pavement over
the life of the structure. It is therefore imperative that even after construction of
improvements, the moisture contents are maintained at relatively constant levels,
allowing neither excessive wetting or drying of soils.
NorCal Engineering
August 17, 2018 Project Number 17201-13
Page 7
Evidence of excessive wetting of expansive soils may be seen in concrete slabs, both
interior and exterior. Slabs may lift at construction joints producing a trip hazard or may
crack from the pressure of soil expansion. Wet clays in foundation areas may result in
lifting of the structure causing difficulty in the opening and closing of doors and windows,
as well as cracking in exterior and interior wall surfaces. In extreme wetting of soils to
depth, settlement of the structure may eventually result. Excessive wetting of soils in
landscape areas adjacent to concrete or asphaltic pavement areas may also result in
expansion of soils beneath pavement and resultant distress to the pavement surface.
Excessive drying of expansive soils is initially evidenced by cracking in the surface of
the soils due to contraction. Settlement of structures and on -grade slabs may also
eventually result along with problems in the operation of doors and windows.
Projects located in areas of expansive clay soils will be subject to more movement and
"hairline" cracking of walls and slabs than similar projects situated on non -expansive
sandy soils. There are, however, measures that developers and property owners may
take to reduce the amount of movement over the life the development. The following
guidelines are provided to assist you in both design and maintenance of projects on
expansive soils:
Drainage away from structures and pavement is essential to prevent
excessive wetting of expansive soils. Grades of at least 3% should be
designed and maintained to allow flow of irrigation and rain water to
approved drainage devices or to the street. Any "ponding" of water adjacent
to buildings, slabs and pavement after rains is evidence of poor drainage; the
installation of drainage devices or regrading of the area may be required to
assure proper drainage. Installation of rain gutters is also recommended to
control the introduction of moisture next to buildings. Gutters should
discharge into a drainage device or onto pavement which drains to roadways.
Irrigation should be strictly controlled around building foundations, slabs and
pavement and may need to be adjusted depending upon season. This
control is essential to maintain a relatively uniform moisture content in the
expansive soils and to prevent swelling and contracting. Over -watering
adjacent to improvements may result in damage to those improvements.
NorCal Engineering makes no specific recommendations regarding
landscape irrigation schedules.
Planting schemes for landscaping around. structures and pavement should
be analyzed carefully. Plants (including sod) requiring high amounts of water
may result in excessive wetting of soils. Trees and large shrubs may actually
extract moisture from the expansive soils, thus causing contraction of the
fine-grained soils.
L
NorCal Engineering
�I
August 17, 2018
Page 8
Project Number 17201-13
Thickened edges on exterior slabs will assist in keeping excessive moisture
from entering directly beneath the concrete. A six-inch thick or greater
deepened edge on slabs may be considered. Underlying interior and exterior
slabs with 6 to 12 inches or more of non -expansive soils and providing
presaturation of the underlying clayey soils as recommended in the soil
report will improve the overall performance of on -grade slabs.
Increase the amount of steel reinforcing in concrete slabs, foundations and
other structures to resist the forces of expansive soils. The precise amount
of reinforcing should be determined by the appropriate design engineers
and/or architects.
Recommendations of the soil report should always be followed in the
development of the project. Any recommendations regarding presaturation
of the upper subgrade soils in slab areas should be performed in the field
and verified by the Soil Engineer.
NorCal Engineering
APPENDICES
(In order of appearance)
Appendix A — Laboratory Tests
Table I — Maximum Density Tests
Table II — Expansion IndexTests
Table III — Sulfate Tests
Appendix B — Summary of Compaction Tests
Site Plan
Summary of Compaction Tests
NorCal Engineering
Appendix A
NorCal Engineering
August 17, 2018
Page 9
Sample
I
I
III
TABLE
MAXIMUM DENSITY TESTS
(ASTM: D1557-12)
Classification
Clayey sandy SILT
Clayey sandy SILT
Crushed Miscellaneous Base
TABLE II
;PANSION INDEX TES'
(U.B.C. STD. 4829-11)
Sample Classification
Pad Subgrade Clayey sandy SILT
TABLE III
SULFATE TESTS
Sample
Pad Subgrade
Project Number 17201-13
Optimum
Maximum Dry
Moisture
Density (lbs./cu.ft.)
12.5
116.0
13.5
114.5
8.5
122.5
Expansion
Index
58
Sulfate (% by Weight)
0.010
NorCal Engineering
Appendix B
NorCal Engineering
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LOCATION OF COWACTION TESTS
August 17, 2018
Page 10
Project Number 17201-13
SUMMARY OF COMPACTION TEST RESULTS
Date of
Test
Percent
Unit Wt.
Relative
Soil Test
Test
No.
Location
Depth
Moisture
lbs./cu.ft.
Compaction
Tvoe S/D
6/1/16
101
Slab Subgrade
0.0-0.5
14.1
105.8
91
1 D
6/3/16
102
Slab Subgrade
0.0-0.5
14.4
108.9
94
1 S
6/23/16
103
Wall Backfill
4.04.5
13.9
107.5
93
1 D
6/23/16
104
Wall Backfill
3.0-3.5
13.4
105.8
91
1 D
6/24/16
105
Wall Backfill
1.0-1.5
13.1
107.8
93
1 D
6/27/16
106
Wall Backfill
1.0-1.5
14.5
106.6
93
11 S
6/27/16
107
Wall Backfill
1.0-1.5
13.2
105.4
91
1 D
6/28/16
108
Wall Backfill
0.0-0.5
12.7
106.4
92
1
7/1/16
109
Wall Backfill
0.5-1.0
12.2
104.6
91
II S
7/1/16
110
Wall Backfill
7.0-7.5
12.5
106.7
92
1 D
7/1/16
111
Wall Backfill
5.0-5.5
12.2
106.4
92
1 D
7/5/16
112
Wall Backfill
3.0-3.5
11.4
109.5
94
1 D
7/6/16
113
Wall Backfill
1.0-1.5
11.0
105.2
91
1 S
7/6/16
114
Wall Backfill
0.0-0.5
11.2
107.0
92
1 D
7/6/16
115
Wall Backfill
0.0-0.5
11.6
108.4
93
1 D
7/7/16
116
Site Grading
3.5-4.0
12.4
107.7
94
II D
7/8/16
117
Site Grading
1.5-2.0
12.2
108.3
93
1 S
7/8/16
118
Site Grading
0.0-0.5
11.8
107.0
92
1 D
7/8/16
119
Site Grading
0.0-0.5
11.6
108.4
93
1 D
7/11/16
120
Site Grading
3.0-3.5
12.2
105.2
91
1 D
7/11/16
121
Site Grading
1.0-1.5
11.9
105.3
94
II S
7/11/16
122
Site Grading
0.0-0.5
11.5
108.3
93
1 D
8/5/16
123
Garage Slab
0.0-0.5
14.0
105.3
91
1 D
12/8/17
124
Drain Line
0.0-0.5
10.4
109.6
94
1 D
12/8/17
125
Drain Line
0.0-0.5
11.8
106.4
92
1 D
12/8/17
126
Drain Line
0.0-0.5
11.0
105.4
91
1 D
12/8/17
127
Drain Line
0.0-0.5
11.4
108.0
93
1 S
2/27/18
128
Pool Bottom
0.0-0.5
15.5
104.6
91
II D
2/27/18
129
Pool Bottom
0.0-0.5
15.4
106.8
93
II S
6/13/18
130
Sidewalk Subgrd
0.0-0.5
12.9
109.0
94
1 D
6/13/18
131
Driveway Base
0.0-0.5
8.5
116.5
95
III S
"Retest of failing tests after area reworked
S= Sand Cone Method
D= Drive Tube Method
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