HomeMy WebLinkAboutE2016-0337 - SoilsCOAST GEOTECHNICAL, INC.
1200 W. Commonwealth Avenue, Fullerton, CA 92833 * Ph: (714) 870-1211 * Fax: (714) 870-1222 * E-mail: coastgeotec@sbcglobal.net
October 15, 2019
Mr. and Mrs. John Manly
2612 Mesa Drive
Newport Beach, CA 92660
References:
W.O. 557918-03
Subject: Rough Grade Compaction Report for
Additions at 2612 Mesa Drive, Newport
Beach, California
Geotechnical Engineering Investigation of Proposed Additions, 2612 Mesa Drive, Newport
Beach, California; by COAST GEOTECIINICAL, INC., W.O. 557918-01, dated August 21,
2018.
Response to Geotechnical
Newport Beach, California
December 5, 2018.
Dear Mr. & Mrs. Manly:
Report Review for Proposed Additions at 2612 Mesa Drive,
by COAST GEOTECBNICAL, INC., W.O. 557918-02, dated
Forwarded herewith is the rough grade compaction report for the subject site. Our observations
and testing were performed periodically, as requested. The grading operation for the residential
development consisted of grading the pad area to provide uniformly compacted fill soils for
support of the residence. The grading operation was conducted from October 7, 2019 through
October 11, 2019.
PLACEMENT OF FILL
Compacted fill material was placed to provide adequate support for the proposed structure.
The over -excavation of the building pad area extended into competent native material. The depth
of over -excavation was approximately three to five feet below the original grade. The proposed
finish grade varies from two feet above to two feet below original grade. The exposed surface
was scarified, moisture conditioned, and compacted to a minimum of 90% relative compaction.
Subsequent fills were placed in six to eight inch loose lifts, moisture conditioned as needed, and
compacted to a minimum of 90% relative compaction by track rolling. This process was
followed to finish grade.
Hardscape areas outside the building pad were over -excavated about 12 inches and recompacted
to final grade to a minimum of 90% relative compaction. The driveway area was only partially
graded. The remainder of the driveway will be graded at a later date.
Limits of grading are shown on the attached Plate 1.
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 2 W.O. 557918-01
Rough Grade Compaction Report October 15, 2019
Equipment used for the compaction of fill soils consisted of a Cat 953 track loader. Soils were
moisture conditioned by a water hose. Earthwork was by JD Demolition & Grading.
TESTING
Maximum density optimum moisture relationship determinations were performed for each soil
type encountered during grading operations. Test results were as follows:
Laboratory Standard: (ASTM:D-1557)
4-inch diameter mold; 1/30 ft3 volume;
5 layers at 25 blows per layer;
10 lb. hammer dropped 18 inches
Soil Type
Classification
Optimum Moisture, %
Max. Dry Density, lbs/ft3
1
Orange Brown Silty Clayey
9.5
125.0
Sand
II
Orange Brown Silty Clayey
9.0
127.0
Sand
Compaction tests were performed a minimum of every two feet and/or 500 cubic yards of
compacted fill soils placed. These tests were performed in accordance with an ASTM test
method. The test results are summarized in Table 1. The approximate test locations are shown on
Plate 1.
FOUNDATIONS IN COMPACTED FILL
The proposed additions may be supported by conventional foundations system deriving support
from new engineered fill soil where feasible.
Conventional foundations may consist of spread footings or isolated pads placed a minimum
depth of 24 inches below lowest adjacent grade utilizing an allowable bearing value of
1,800 pounds per square foot. This value is for dead plus live load and may be increased 1/3 for
total including seismic and wind loads where allowed by code. The footing width shall be at least
15 inches for the proposed two-story addition.
Isolated pad footings shall be tied by grade beams to continuous footings.
It is recommended that all footings be reinforced with a minimum of four #5 bars (two top and
two bottom). The structural engineer's reinforcing requirements should be followed if more
stringent.
Footing excavations shall be observed by a representative of COAST GEOTECHNICAL, Inc.,
prior to placement of steel or concrete to verify competent soil conditions. If unacceptable soil
conditions are exposed mitigation will be recommended.
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 3 W.O. 557918-01
Rough Grade Compaction Report October 15. 2019
FOUNDATIONS INTO COMPETENT NATIVE EARTH MATERIAL
Where grading is not performed new foundations may be supported by competent native earth
material utilizing the following design.
Continuous footings placed a minimum of 12 inches into competent native earth material and at
least 24 inches below lowest adjacent grade, whichever is deeper, may utilize an allowable
bearing value of 1,800 psf. This value is for dead plus live load and may be increased by 1/3 for
total including seismic and wind loads where allowed by code.
Isolated pads placed a minimum of 12 inches into competent native earth material and at least 24
inches below lowest adjacent grade, whichever is deeper, may utilize an allowable bearing value
of 1,800 psf This value is for dead plus live load and may be increased by 1/3 for total including
seismic and wind loads where allowed by code. Isolated pads shall be tied into adjacent
foundations with designed grade beams in at least two directions.
Minimum geotechnical reinforcement of foundations shall be four #5 bars, two top and two
bottom. Structural design may require additional reinforcement.
Foundation excavations shall be observed by the project soil engineer to verify embedment
requirements into competent earth material and compliance with project geotechnical
requirements. Dependent on conditions exposed the project soils engineer may require the
foundation excavations to be extended deeper or mitigation performed.
LATERAL DESIGN
Lateral restraint at the base of footings and on slabs may be assumed to be the product of the
dead load and a coefficient of friction of .30. Passive pressure on the face of footings may also be
used to resist lateral forces. A passive pressure of zero at the surface of finished grade, increasing
at the rate of 300 pounds per square foot of depth to a maximum value of 3,000 pounds per
square foot, may be used for compacted fill and native soils at this site. If passive pressure and
friction are combined when evaluating the lateral resistance, then the value of the passive
pressure should be limited to 2/3 of the values given above.
EXPANSIVE SOILS
Results of expansion tests indicate that the near surface soil at the completion of grading has a
medium expansion potential. Irrigation should be controlled, limited and directed away from
foundations.
SOLUBLE SULFATES
Typical on -site soils showed a soluble sulfate content of 33 ppm. This sulfate exposure is
negligible. Type II concrete with minimum 2,500 psi compressive strength may be used and
designed per the CBC and ACI.
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 4 W.O. 557918-01
Rough Grade Compaction Report October 15, 2019
FLOOR SLABS
Where a slab on grade is utilized, the slab shall be supported on engineered fill compacted to a
minimum of 90% relative compaction.
Minimum geotechnical recommendations for on grade slab design are five inches actual
thickness with #4 bars at twelve inches on center each way.
Subgrade soil should be kept moist prior to casting the slab. However, if the soils at grade become
disturbed during construction, they should be moisture conditioned to 3% to 4% over optimum
moisture, and compacted to a minimum of 90% relative compaction prior to placing concrete.
COAST GEOTECHNICAL, Inc. will need to verify adequate mitigation.
The capillary break material shall comply with the requirements of the local jurisdiction and
shall be a minimum of four inches in thickness. The city of Newport Beach requires the use of
four inches of gravel (1/2-inch or larger clean aggregate). If gravels are used, a heavy filter
fabric (Mirafi 140N) must be placed over the gravels prior to placement of the recommended
vapor barrier to minimize puncturing of the vapor barrier. Additionally, a vibratory plate should
be used over the gravels prior to placement of the recommended filter fabric to smooth out any
sharp protuberances and consolidate the gravels.
Slab areas should be underlain by a vapor retarder consisting of an engineered plastic film (as
described by ASTM:E-1745). In areas where a moisture sensitive floor covering will be used
and/or where moisture infiltration is not desirable, a vapor barrier with a permeance of less than
0.01perms (consistent with ACI 302.2R-06) such as 15 mil. Stego Wrap Vapor Barrier, or
equivalent should be considered, and a qualified water proofing specialist should be consulted.
The vapor barrier should be underlain by the above described capillary break materials and filter
cloth. The capillary break materials should be compacted to a uniform condition prior to
placement of the recommended filter cloth and vapor barrier. The vapor barrier should be
properly lapped and sealed, and in contact with the slab bottom.
UTILITY LINE BACKFILLS
All utility line backfills, both interior and exterior, shall be compacted to a minimum of
90% relative compaction and shall require testing at a maximum of two -foot vertical intervals.
Underground pipes shall be shaded with a minimum of one foot of sand.
Where utility lines enter structures the utility trench shall have an impermeable plug of backfill
placed to mitigate the potential migration of waters through the backfill zone underneath the
slab.
Utility lines shall be placed at appropriate depths. Shallow pipes can be damaged by the forces
imposed by compacting backfill soils. If shallow pipes are not capable of withstanding the forces
of backfill compaction, slurry backfill will be recommended.
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 5 W.O. 557918-01
Rough Grade Compaction Report October 15, 2019
HARDSCAPE AND SLABS
Hardscape slab subgrade areas shall exhibit a minimum of 90% relative compaction and
moisture content near optimum moisture content to a depth of at least one foot. Deeper removal
and recompaction may be required if unacceptable conditions are encountered. These areas
require testing just prior to placing concrete.
The followings recommendations will minimize cracking and offsets, but will not eliminate
concrete cracks. Minimum geotechnical recommendations for slab design are 4 inches actual
thickness with #3 bars at twelve inches on center each way.
As an alternative to rigid hardscape or brickwork, flexible pavers may be utilized.
DRAINAGE
Positive drainage should be planned for the site. Drainage should be directed away from
structures via non -erodible conduits to suitable disposal areas. The structure should utilize roof
gutters and down spouts tied directly to yard drainage.
Unlined flowerbeds, planters, and lawns should not be constructed against the perimeter of the
structure. If such landscaping (against the perimeter of a structure) is planned, it should be
properly drained and lined or provided with an underground moisture barrier. Irrigation should
be kept to a minimum.
While the current CBC recommends 5% slope away from structures for landscape areas, 2% slope
is allowable where justified. Our justification is the use roof drains tied into area drains, the use of
area drains, and site grading which will mitigate the potential for moisture problems beneath a slab
on grade. Hardscape areas shall be sloped a minimum of 2% where within ten feet of the residence
unless allowed otherwise by the building official.
We do not recommend the use of bottomless trench drains to conform with infiltration best
management practice (BMP) such as infiltration trenches, infiltration basins, dry wells,
permeable pavements or similar systems designed primarily to percolate water into the
subsurface soils within ten feet of foundations. If infiltration system cannot be located away from
foundations, from a geotechnical viewpoint surface drainage should be directed to the street or
approved area in accordance with the Civil engineer.
POST -GRADING SERVICES
During construction of the residence, it is recommended, and at times required by the regulatory
agency, the following be observed and/or tested by the geotechnical engineer:
• Excavation of foundations
• Backfill of interior trenches
• Backfill of interior slab areas
• Backfill of exterior utility trenches
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 6 W.O. 557918-01
Ron& Grade Compaction Report October 15 2019
Hardscape subgrade
It is the responsibility of the developer to schedule the required observations and testing.
REGULATORY COMPLIANCE
I hereby certify that the subject grading was observed by a representative from this office, and
the work was done in full compliance with the Grading Ordinance of the City of Newport Beach
and in accordance with the best accepted practices of the applicable chapter of the California
Building Code.
All cuts, fills or processing of original ground under the purview of this report have been
completed under the observation of and with selective testing by COAST GEOTECHNICAL,
INC. and found to be in compliance with the Grading Code of the City of Newport Beach. The
completed work has been observed by COAST GEOTECHNICAL, INC., and is considered
adequate for the development. Our findings were made and recommendations prepared in
accordance with generally accepted professional engineering practices, and no further warranty
is implied nor made.
This report is subject to review by the controlling authorities for this project.
We appreciate this opportunity to be of service to you.
Respectfully submitted:
COAST GEOTECHNICAL, INC.
Ming-Tarng Chen
RCE54011 Q�p�ARNC
No.54011
Exp. 12/31 /19
Darnel E. ere
Staff Geologist
COAST GEOTECHNICAL, INC.
Mr. & Mrs. Manly 7 W.O. 557918-01
Rough Grade Compaction Report October 15, 2019
COMPACTION TEST RESULTS
TABLE 1
Test
No.
Location
Below
Proposed
Grade (ft)
Moisture
Content
%
Dry Unit
Weight
(lbs/fti)
Soil
Type
Relative
Compaction
%
Date
1
Pad Area
3.0-3.5
7.5
115.6
I
92.5
10/7/19
2
Pad Area
3.0-3.5
8.0
118.0
I
94.4
10/7/19
3
Pad Area
2.0-2.5
10.5
116.3
I
93.0
10/8/19
4
Pad Area
1.0-1.5
9.8
117.5
I
94.0
10/8/19
5
Pad Area
0.5-1.5
11.9
116.7
I
93.4
10/8/19
6
Pad Area
3.0-3.5
11.5
116.3
I
93.0
10/8/19
7
Pad Area
3.0-3.5
12.8
115.1
I
92.1
10/8/19
8
Pad Area
1.5-2.0
13.1
115.2
1
92.2
10/8/19
9
Pad Area
1.5-2.0
11.4
117.5
1
94.0
10/8/19
10
Pad Area
0.5-1.0
10.0
117.6
1
94.1
10/9/19
11
Pad Area
0.0-0.5
10.0
117.4
I
93.9
10/9/19
12
Pad Area
1.0-1.5
15.1
114.2
I
91.4
10/9/19
13
Pad Area
1.0-1.5
13.7
118.7
H
93.5
10/10/19
14
Pad Area
0.0-0.5
15.1
114.0
I
91.2
10/10/19
15
Pad Area
0.5-1.0
9.9
119.3
II
93.9
10/10/19
16
Pad Area
F.G.
12.9
118.6
H
93.4
10/11/19
17
Pad Area
F.G.
13.2
119.3
H
93.9
10/11/19
P19 18
Pad Area
F.G.
12.5
117.7
II
92.7
10/11/19
Pad Area
F.G.
13.4
118.4
II
93.2
10/11/19
F.G. Final Grade
L EXIST PR' SEWEAJ
IYATEL
L
Approximate
Compaction
L Test Location
SITE PLAN, Partial
.0,a-w-0- weal
-i- - -! - - -\ - - ----- Scale 1" = 30'
ti
. 7
Approximate
Limits of Grading
For Hardscape
COAST GEOTECHNICAL, INC.
EXIST HOUSE
TO REMAIN