2004-9109 G Ar D
j GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
12 May 2004
(Revised 28 May 2004)
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
C/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Rear Yard Cut Slope Re-grading
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with your request and our proposal of April 27, 2004, we are
providing general recommendations for re-grading of the existing upper cut slope
located in the northwest corner of your rear yard. As discussed in our letter of April
21, 2004, excavation for proposed yard area retaining walls resulted in temporary
cuts 6 to 8 feet in height along the west side of your home. We understand that
you wish to eliminate the higher, 8-foot cut that crosses the upper northwest corner
of your yard, if feasible, through a cut and fill grading operation. Based on our site
review as well as the site plan by Conway and Associates, Inc., it is our opinion that
minor cut and fill grading can be utilized to eliminate the temporary cut slope.
Refer to the Vicinity Map, Figure No. I, for the approximate site location.
We have provided Figure No. II to depict the areas of proposed cutting and filling
and Figure No. III to illustrate how such grading will eliminate the existing near-
vertical 8-foot slope. As shown on the figures, the upper cut slope should be re-cut
at approximately 1.0 horizontal to 1.0 vertical and the lower fill slope that will
retain the lower half of the existing vertical cut can be placed at approximately 2.0
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
horizontal to 1.0 vertical. The retaining wall design values presented in our letter
of April 21, 2004, are still valid for any wall location with a level or gently sloping
backfill. At locations where a 1.5:1.0 (horizontal to vertical) slope is to be retained,
the wall should be designed utilizing an equivalent fluid weight of 52 pcf.
Fill soils must be properly placed and compacted to a minimum degree of
compaction of 90 percent and be tested by our staff, in accordance with ASTM
D1557. This information should be provided to your civil engineers for inclusion on
the grading plan.
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC. ���CD y ��
D.
1 . REED
Leslie D. Reed r sident c i r'-D
C.E.G. 999[exp. 3-31-05]/R.G. 3391
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Wm. D. Hes er, G.E. o R ID 11 X
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R.C.E. 26222/G.E. 396
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4rp4 SOIL GEOTECHNICAL EXPLORATION, INC,
&FOUNDATION ENGINEERING - GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT - ENGINEERING GEOLOGY
31 August 2004
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
c/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Response to City Review
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we are responding to comments and questions by the Geotechnical
Reviewer for the City of Encinitas in his memorandum dated August 12, 2004. The
reviewer's questions regarding the geologic conditions in the area of the proposed
cuts were addressed in our report dated April 21, 2004, which was not provided to
him. We are enclosing a copy of that report for submission with this letter.
We are also attaching the summary results of stability analyses for the proposed
1:1 cut slope, which indicate a factor of safety greater than 1.5. The stability
analysis was performed using XSTABLE Version 5.2 to back-calculate the cohesion
exhibited by the existing near vertical. The back-calculated cohesion was then used
to analyze the stability of the 1:1 cut slope.
In addition, we have reviewed the preliminary, undated grading plans prepared by
Conway and Associates for the proposed grading and retaining wall construction.
In our opinion, the plans have incorporated our recommendations. We recommend,
however, that retaining wall detail 5 on sheet 2 be revised to delete the "rock
7420 TRADE STREET - SAN DIEGO, CA 92121 - (858)549-7222 - FAX: (858)549-1604 - E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
pocket" and PVC subdrain pipe and be revised to indicate Miradrain 6200 or
equivalent with a bottom section of Quickdrain or equivalent. The top of the
Miradrain should terminate at least 12 inches below the finish grade surface.
Surface drains should not flow into the subdrain system.
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted, wow G(r��
LOLM
0.
GEOTECHNICAL EXPLORATION, INC. RM
110.4®A �
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slie D. Reed, President .gP oaf
C.E.G. 999[exp. 3-31-os]/R.G. 3391
� 4G.E. QWm. D. Hes er, �� ID
R.C.E. 26222/G.E. 396 � �•
3 0 96 m
UP. 3/31/2006
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PROFIL FILE: VANK2 8-30-** 13 : 30 ft
VanCleve existing near vertical
5 5
100 . 0 283 . 0 110 . 0 283 . 0 1
110 . 0 283 . 0 110 . 1 291 . 0 1
110 . 1 291 . 0 115 . 2 295 . 0 1
115 . 2 295 . 0 118 . 7 296 . 0 1
118 . 7 296 . 0 125 . 5 298 . 0 1
SOIL
1
115 . 0 125 . 0 305 . 0 . 00 . 000 . 0 0
RANDOM
1 2000
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. 0 . 0 . 0 . 0
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PROFIL FILE : VANK3 8-30-** 14 : 09 ft
VanCleve 1 : 1 cut slope in Torrey
4 4
100 . 0 282 . 0 110 . 0 287 . 0 1
110 . 0 287 . 0 118 . 7 296 . 0 1
118 . 7 296 . 0 125 . 5 298 . 0 1
125 . 5 298 . 0 138 . 0 300 . 0 1
SOIL
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115 . 0 125 . 0 305 . 0 . 00 . 000 . 0 0
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110 . 0 110 . 0 120 . 0 135 . 0
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1rIE-j j GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING - GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT - ENGINEERING GEOLOGY
21 April 2004
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
c/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Retaininci Wall Design, Geotechnical Criteria
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we have reviewed the existing excavations placed to accommodate
retaining wall construction along the western and north side rear yard of your
home. The property, currently improve with a two-story, single-family home, is
accessed by a concrete driveway off the west side of Lake Drive. The property is
further defined by APN 260-523-17.
Prior to our visit, we received a grading plan showing the proposed wall
improvements. The plan also showed the new pool and spa locations. Guniting of
the pool and spa had been completed at the time of our visit.
During the site review, our Certified Engineering Geologist noted that vertical cuts 6
to 8 feet in height, as well as initial footing excavations, had been placed along the
proposed wall alignment. The cuts expose dense, light brown, fine- to medium-
grained Torrey Sandstone of Eocene age. Due to the density and moderately
cemented nature of the Torrey Sandstone, the cuts are considered stable and
7420 TRADE STREET - SAN DIEGO, CA 92121 - (858)549-7222 - FAX: (858)549-1604 - E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
acceptable as temporary construction slopes. Wall construction should, however,
proceed as soon as possible.
Although the existing footing excavations extend into the Torrey Sandstone, which
has excellent bearing characteristics, they appear to be undersized and will require
redigging after an engineered wall design is completed.
We recommend that the wall be designed utilizing footing foundations that extend
at least 18 inches into the undisturbed formational sandstone. At the
recommended depth, the footings may be designed for allowable bearing pressures
of 3,500 pounds per square foot (psf) for combined dead and live loads, and 4,700
psf for all loads including wind or seismic. The footings should, however, have a
minimum width of 12 inches. In order for us to offer an opinion as to whether the
footings are founded on soils of sufficient load bearing capacity, it is essential that
our representative inspect the footing excavations prior to the placement of
reinforcing steel or concrete. All loosened, disturbed formational soils should be
removed from the excavations to expose dense, undisturbed sandstone.
Lateral load resistance for the walls supported on footing foundations may be
developed in friction between the foundation bottoms and the supporting subgrade.
An allowable friction coefficient of 0.35 is considered applicable. An additional
allowable passive resistance equal to an equivalent fluid weight of 350 pounds per
cubic foot acting against the foundations may be used in design provided the
footings are poured neat against the adjacent undisturbed formational sandstone
materials. These lateral resistance values assume a level surface in front of the
footing for a minimum distance of three times the embedment depth of the footing
and any shear keys and are based on a factor of safety of 1.5.
The subject retaining walls consists of a combination of curvilinear layouts and
straight segments that terminate with right-angle return sections. The curvilinear
Pl"-
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 3
segments, as well as the straight segments extending 10 feet each way from the
angle points, should be designed for a restrained condition. The remainder of the
straight line segments may be designed for an unrestrained condition. We
recommend that the unrestrained (cantilever) wall sections be designed for an
equivalent fluid pressure of 35 pounds per cubic foot (pcf). Cantilever conditions
are defined as walls capable of horizontal movements of at least 0.005H at the top
of the wall, where H is the height of the wall, in feet. We recommend that the
restrained wall sections be designed for an equivalent fluid weight of 35 pcf plus an
additional uniform lateral pressure of 5H pounds per square foot, where H is the
height of the backfill above the top of the wall footing, in feet.
The preceding design pressures are based on sufficient drainage behind the walls to
prevent the build-up of hydrostatic pressures from surface water infiltration.
Adequate drainage may be provided by means of weepholes with permeable filter
material installed behind the walls.
Backfill placed behind the walls should be compacted to a minimum degree of
compaction of 90 percent using light compaction equipment. If heavy equipment is
used, the walls should be appropriately temporarily braced.
LIMITATIONS
Our assessment has been limited to providing the geotechnical criteria required for
design of the proposed western and northern yard area retaining walls. Verification
by our staff that footings have been properly cleaned of all loose material is
required prior to placement of steel reinforcing or concrete. It is not within the
scope of our assignment to address waterproofing or drainage behind the walls or
geotechnical conditions beyond the areas of the proposed western and northern
yard area improvements.
4r,
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 4
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC. _
L E'fy��rf) GF,
f' '; IE Q(
Les ie Reed, President J r" =
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 4
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC. _
r \ �Or'
LiE
Les ie Reed, President / F--7=D 1
C.E.G. 999[exp. 3-31-05]/R.G. 3391
C_R1! !c^
Wm. D. Hesp , G.E.
R.C.E. 26222/G.E. 396
W " No.396
cc a
Exp. 3/31/2006v
s!'FOTfCFIN��'P�Q
9�0F CAL1E���
Arp4Djl GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
j HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
27 September 2004
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
c/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014 (_—� >
Attn: Ms. Nancy Patterson
I
Subject: Response to City Review
Van Cleve Residence _ SEP
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we are responding to requirements by the Geotechnical Reviewer for
the City of Encinitas in his memorandum dated September 23, 2004. The reviewer
indicates the City will not approve slopes that are steeper than 1.5 horizontal to 1.0
vertical. In addition, the City requires mass and surficial stability calculations.
The mass stability analysis was performed using XSTABLE Version 5.2 to back-
calculate the cohesion exhibited by the existing near vertical cut. The back-
calculated cohesion was then used to analyze the mass stability of the 1.5 to 1.0
cut slope. For surficial stability calculations, we have utilized a reduced cohesion
value of 200 psf and an angle of internal friction of 32 degrees to represent the
saturated strength of the Torrey Sandstone cut. In our opinion, a saturated depth
of 1 foot is conservative for the proposed cut slope. The results of our stability
analyses are attached and indicate a factor of safety in excess of 1.5 for both mass
and surficial stability.
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
s �0
3 ✓ L`SUS '�
l�
GEO HNICAL EXPLORATIO C.
P �; t D
j 0 .9
a7r
CERl! _'D
L ie D. Reed, resident c_1. ,,", a�
C.E.G. 999[exp. 3-31-os]/R.G. 3391 `�1� '0� CA0F
Wm. D. Hespel , G.E. ' oP�\C HA
R.C.E. 26222/G.E. 396
3 No.396
* Exp. 3/31/2006 v
`rl0 CHN��Q►�Q
OF CALIF.
XSTABL File: VANK2 9-24-** 14:49
* XSTABL
*
* Slope Stability Analysis
* using the
* Method of Slices
* *
* Copyright(C) 1992-96
* Interactive Software Designs, Inc.
* Moscow,ID 83843,U.S.A.
* *
* All Rights Reserved
* *
* Ver. 5.200 96- 1358
******************************************
Problem Description : VanCleve existing near vertical back calculation
-----------------------------
SEGMENT BOUNDARY COORDINATES
-----------------------------
5 SURFACE boundary segments
Segment x-left y-left x-right y-right Soil Unit
No. (ft) (ft) (ft) (ft) Below Segment
l 100.0 283.0 110.0 283.0 1
2 110.0 283.0 110.1 291.0 1
3 110.1 291.0 115.2 295.0 1
4 115.2 295.0 118.7 296.0 1
5 118.7 296.0 125.5 298.0 1
--------------------------
ISOTROPIC Soil Parameters
--------------------------
1 Soil unit(s)specified
Soil Unit Weight Cohesion Friction Pore Pressure Water
Unit Moist Sat. Intercept Angle Parameter Constant Surface
No. (pcf) (pcf) (psf) (deg) Ru (psf) No.
1 115.0 125.0 305.0 .00 .000 .0 0
A critical failure surface searching method,using a random
technique for generating IRREGULAR surfaces has been specified.
2000 trial surfaces will be generated and analyzed.
2000 Surfaces initiate from each of 1 points equally spaced
along the ground surface between x= 110.0 ft
and x= 110.0 ft
Each surface terminates between x= 112.0 ft
and x= 124.5 ft
Unless further limitations were imposed,the minimum elevation
at which a surface extends is y= .0 ft
* * * * * DEFAULT SEGMENT LENGTH SELECTED BY XSTABL
5.0 ft line segments define each trial failure surface.
---------------------
ANGULAR RESTRICTIONS
---------------------
The first segment of each failure surface will be inclined
within the angular range defined by
Lower angular limit:= -45.0 degrees
Upper angular limit:_ (slope angle-5.0)degrees
Factors of safety have been calculated by the
* * * * * SIMPLIFIED JANBU METHOD
The 10 most critical of all the failure surfaces examined
are displayed below-the most critical first
Failure surface No. 1 specified by 6 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 114.63 284.89
3 118.96 287.39
4 122.23 291.17
5 124.49 295.64
6 124.49 297.70
** Corrected JANBU FOS= 1.014 ** (Fo factor= 1.085)
Failure surface No. 2 specified by 6 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 114.34 285.48
3 118.20 288.66
4 121.86 292.06
5 124.24 296.46
6 124.24 297.63
** Corrected JANBU FOS= 1.037 ** (Fo factor= 1.063)
Failure surface No. 3 specified by 6 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 113.85 286.19
3 117.68 289.40
4 121.43 292.71
5 124.13 296.92
6 124.13 297.60
** Corrected JANBU FOS= 1.067 ** (Fo factor= 1.044)
Failure surface No.4 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 113.86 286.17
3 11739 289.72
4 120.46 293.66
5 122.94 297.25
** Corrected JANBU FOS= 1.1 16 ** (Fo factor= 1.032)
Failure surface No. 5 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 113.85 286.19
3 117.04 290.04
4 120.48 293.67
5 122.90 297.24
** Corrected JANBU FOS= 1.118 ** (Fo factor= 1.024)
Failure surface No. 6 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 114.07 285.90
3 117.18 289.82
4 120.15 293.84
5 123.42 297.39
** Corrected JANBU FOS= 1.122 ** (Fo factor= 1.033)
Failure surface No. 7 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 113.81 286.24
3 117.20 289.92
4 120.46 293.70
5 122.56 297.14
** Corrected JANBU FOS= 1.124 ** (Fo factor= 1.027)
Failure surface No. 8 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 113.81 286.23
3 117.49 289.62
4 120.42 293.67
5 123.03 297.27
** Corrected JANBU FOS= 1.125 ** (Fo factor= 1.035)
Failure surface No. 9 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 1 14.39 285.38
3 117.87 288.98
4 120.54 293.20
5 123.19 297.32
** Corrected JANBU FOS= 1.134 ** (Fo factor= 1.054)
Failure surface No.10 specified by 5 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 283.00
2 114.27 285.61
3 1 17.92 289.02
4 120.84 293.08
5 123.26 297.34
** Corrected JANBU FOS= 1.135 ** (Fo factor= 1.053)
The following is a summary of the TEN most critical surfaces
Problem Description :VanCleve existing near vertical
Modified Correction Initial Terminal Available
JANBU FOS Factor x-coord x-coord Strength
(ft) (ft) (lb)
1. 1.014 1.085 110.00 124.49 6.103E+03
2. 1.037 1.063 110.00 124.24 6.102E+03
3. 1.067 1.044 110.00 124.13 6.102E+03
4. 1.116 1.032 110.00 122.94 5.903E+03
5. 1.118 1.024 110.00 122.90 5.890E+03
6. 1.122 1.033 110.00 123.42 6.048E+03
7. 1.124 1.027 110.00 122.56 5.802E+03
8. 1.125 1.035 110.00 123.03 5.931E+03
9. 1.134 1.054 110.00 123.19 6.067E+03
10. 1.135 1.053 110.00 123.26 6.070E+03
* * * END OF FILE * * *
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XSTABL File: VANK313 9-27-** 10:07
* XSTABL
*
* Slope Stability Analysis
* using the
* Method of Slices
* *
* Copyright(C) 1992—96
* Interactive Software Designs, Inc.
* Moscow, ID 83843,U.S.A.
* *
* All Rights Reserved
* *
* Ver. 5.200 96— 1358
******************************************
Problem Description : VanCleve 1.5 cut slope in Torrey
-----------------------------
SEGMENT BOUNDARY COORDINATES
-----------------------------
3 SURFACE boundary segments
Segment x-left y-left x-right y-right Soil Unit
No. (ft) (ft) (ft) (ft) Below Segment
1 100.0 282.0 110.0 287.0 1
2 110.0 287.0 126.5 298.0 1
3 126.5 298.0 138.0 300.0 1
--------------------------
ISOTROPIC Soil Parameters
--------------------------
1 Soil unit(s)specified
Soil Unit Weight Cohesion Friction Pore Pressure Water
Unit Moist Sat. Intercept Angle Parameter Constant Surface
No. (pcf) (pcf) (psf) (deg) Ru (psf) No.
1 115.0 125.0 305.0 .00 .000 .0 0
A critical failure surface searching method,using a random
technique for generating CIRCULAR surfaces has been specified.
1000 trial surfaces will be generated and analyzed.
1000 Surfaces initiate from each of 1 points equally spaced
along the ground surface between x = 110.0 ft
and x = 110.0 ft
Each surface terminates between x= 129.0 ft
and x = 137.0 ft
Unless further limitations were imposed, the minimum elevation
at which a surface extends is y = 287.0 ft
* * * * * DEFAULT SEGMENT LENGTH SELECTED BY XSTABL
2.0 ft line segments define each trial failure surface.
---------------------
ANGULAR RESTRICTIONS
---------------------
The first segment of each failure surface will be inclined
within the angular range defined by
Lower angular limit :_ -45.0 degrees
Upper angular limit :_ (slope angle- 5.0)degrees
Factors of safety have been calculated by the
* * * * * SIMPLIFIED JANBU METHOD
The 10 most critical of all the failure surfaces examined
are displayed below-the most critical first
Failure surface No. 1 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.02
3 11 3.99 287.17
4 115.98 287.45
5 117.93 287.85
6 119.86 288.38
7 121.75 289.03
8 123.60 289.81
9 125.39 290.70
10 127.12 291.70
11 128.78 292.82
12 130.36 294.04
13 131.87 295.36
14 13328 296.77
15 134.60 29837
16 135.62 299.59
** Corrected JANBU FOS= 1.923 ** (Fo factor= 1.070)
Failure surface No. 2 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.03
3 113.99 287.20
4 115.97 287.48
5 117.93 287.90
6 119.86 288.43
7 121.74 289.09
8 123.59 289.87
9 125.38 290.76
10 127.11 291.77
11 128.77 292.88
12 130.36 294.10
13 131.86 295.41
14 133.28 296.82
15 134.61 298.32
16 135.60 299.58
** Corrected JANBU FOS = 1.936 ** (Fo factor= 1.069)
Failure surface No. ; specified by 16 coordinate points
Point x-surf �-surf
No. (ft) (ft)
I 110.00 287.00
2 112.00 287.04
3 113.99 287.20
4 115.97 287.49
5 117.93 287.90
6 119.86 288.44
7 121.74 289.10
8 123.59 289.88
9 125.38 290.77
10 127.11 291.77
11 128.77 292.89
12 130.36 294.10
13 131.86 295.42
14 133.28 296.82
15 134.61 298.32
16 135.60 299.58
** Corrected JANBU FOS= 1.937 ** (Fo factor= 1.069)
Failure surface No.4 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.04
3 113.99 287.21
4 115.97 287.50
5 117.93 287.91
6 119.85 288.45
7 121.74 289.11
8 123.59 289.89
9 125.38 290.78
10 127.11 291.78
11 128.77 292.89
12 130.36 294.10
13 131.87 295.41
14 133.30 296.81
15 134.63 298.30
16 135.65 299.59
** Corrected JANBU FOS = 1.940 ** (Fo factor= 1.068)
Failure surface No. 5 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.06
3 113.99 287.23
4 115.97 287.53
5 117.92 287.96
6 119.85 288.50
7 121.74 289.16
8 123.58 289.93
9 125.37 290.82
10 127.11 291.81
11 128.78 292.91
12 130.38 294.11
13 131.90 295.41
14 133.34 296.80
15 134.69 298.27
16 135.78 299.61
** Corrected JANBU FOS= 1.950 ** (Fo factor= 1.067)
Failure surface No. 6 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.06
3 113.99 287.25
4 115.97 287.55
5 117.92 287.98
6 119.85 288.52
7 121.74 289.17
8 123.58 289.94
9 125.38 290.82
10 127.12 291.80
11 128.80 292.89
12 130.41 294.07
13 131.95 295.36
14 133.40 296.73
15 134.77 298.19
16 135.99 299.65
** Corrected JANBU FOS= 1.953 ** (Fo factor= 1.066)
Failure surface No. 7 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.08
3 113.99 287.27
4 115.96 287.58
5 117.92 288.01
6 119.84 288.55
7 121.73 289.20
8 123.58 289.97
9 125.38 290.84
10 127.12 291.82
11 128.81 292.90
12 130.42 294.08
13 131.97 295.35
14 133.43 296.71
15 134.82 298.16
16 136.10 299.67
** Corrected JANBU FOS = 1.960 ** (Fo factor= 1.065)
Failure surface No. 8 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.08
3 113.99 287.27
4 115.96 287.58
5 117.92 288.01
6 119.84 288.56
7 121.73 289.21
8 123.58 289.98
9 125.37 290.86
10 127.12 291.85
11 128.79 292.93
12 130.41 294.11
13 131.95 295.39
14 133.41 296.76
15 134.78 298.21
16 135.99 299.65
** Corrected JAN BU FOS= 1.963 ** (Fo factor= 1.066)
Failure surface No. 9 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.09
3 113.99 287.30
4 115.96 287.62
5 117.91 288.06
6 119.83 288.61
7 121.72 289.28
8 123.56 290.06
9 125.36 290.94
10 127.09 291.93
11 128.77 293.02
12 130.38 294.21
13 131.92 295.49
14 133.38 296.86
15 134.75 298.31
16 135.86 299.63
** Corrected JANBU FOS= 1.980 ** (Fo factor= 1.065)
Failure surface No.10 specified by 15 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 110.00 287.00
2 112.00 287.03
3 113.99 287.19
4 1 15.97 287.50
5 117.92 287.95
6 119.83 288.54
7 121.69 289.26
8 123.50 290.11
9 125.25 291.09
10 126.92 292.19
11 128.50 293.41
12 130.00 294.74
13 131.40 296.17
14 132.69 297.70
15 133.84 299.28
** Corrected JANBU FOS= 1.985 ** (Fo factor= 1.072)
The following is a summary of the TEN most critical surfaces
Problem Description : VanCleve 1.5 cut slope in Torrey
Modified Correction Initial Terminal Available
JANBU FOS Factor x-coord x-coord Strength
(ft) (ft) (lb)
1. 1.923 1.070 110.00 135.62 9.046E+03
2. 1.936 1.069 110.00 135.60 9.030E+03
3. 1.937 1.069 110.00 135.60 9.030E+03
4. 1.940 1.068 110.00 135.65 9.040E+03
5. 1.950 1.067 110.00 135.78 9.066E+03
6. 1.953 1.066 110.00 135.99 9.122E+03
7. 1.960 1.065 110.00 136.10 9.144E+03
8. 1.963 1.066 110.00 135.99 9.113E+03
9. 1.980 1.065 110.00 135.86 9.065E+03
10. 1.985 1.072 110.00 133.84 8.527E+03
* * * END OF FILE
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SURFICIAL STABILITY CALCULATIONS
I
d
Slope FZ- - - --Potential Failure Surface
\�e5
0
F
F.S. c + Ybd cos 2 (3 tan
$
YS d sin cos R
Where = angle of internal friction
c = apparent cohesion
Y s = saturated unit weight
Y b = bouyant unit weight
p = slope angle = 33.7 degrees
d = depth to potential failure surface
F.S. = Factor of Safety
Boring Depth c Y Y d
No. (ft) (degrees) (pso (pcf) (pcf) (ft) F.S.
N/A 32 200 125 62.6 1 19
N/A 32 200 125 62.6 2 2.2
N/A 32 100 125 62.6 1 2.0
Surticial Stability 11CL11a11011S
GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
05 November 2004
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
c/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Proposed Cut and Fill Slopes
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we are responding to recent comments by the Geotechnical Reviewer
for the City of Encinitas in his memorandum dated October 29, 2004. Although
revised grading plans are not available at this time, it is our understanding that the
current intent is to utilize 1.5 horizontal to 1.0 vertical cut and/or fill slopes.
Attached are mass stability calculations for 1.5 horizontal to 1.0 vertical cut and/or
fill slopes up to 30 feet in total height. The mass stability analysis, as well as the
attached surficial stability analysis, was performed using XSTABLE Version 5.2. In
our analysis we have utilized a cohesion value of 200 psf and an angle of internal
friction of 32 degrees to represent the saturated strength of the Torrey Sandstone
cut as well as the strength of well-compacted fill soils derived from the Torrey. In
the event imported fill soils are required, they should consist of silty to slightly
clayey sands that possess equal or greater strength than the Torrey materials. In
our opinion, a saturated depth of 2 feet is conservative for the proposed cut and/or
fill slopes. The results of our stability analyses are attached and indicate a factor of
safety in excess of 1.5 for both mass and surficial stability. The City, however, has
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
indicated that they will require that fill slopes steeper than 1.5 to 1.0 incorporate
geotextile reinforcing fabric to enhance the surficial stability. Accordingly, we
recommend that Mirafi 600x or equivalent reinforcing fabric be incorporated in the
fill slopes at 3-foot vertical intervals. The fabric should extend 3 feet horizontally
from the face of the slope.
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
QROFESS�pN
1D HFSA l�
Wm. D. Hes r Senior Geotechnical Engineer v 3� No.396 rn R.C.E. 26222/G.E. 396
� EXP. 3/31/2006 �
CHN�GP�Q'
9lF�F CA Xi
XSTABL File:VAN1X 11-04-** 16:56
* XSTABL
* *
* Slope Stability Analysis
* using the
* Method of Slices
* *
* Copyright(C) 1992-96
* Interactive Software Designs, Inc.
* Moscow. ID 83843, U.S.A.
* *
* All Rights Reserved
* `
* Ver. 5.200 96- 1358
Problem Description • VanCleve 1.5 to 1 fill/cut to 30'
-----------------------------
SEGMENT BOUNDARY COORDINATES
-----------------------------
3 SURFACE boundan segments
Segment x-left %-left x-right }-right Soil Unit
No. (tt) (ft) (ft) (ft) Below Segment
1 .0 100.0 10.0 100.0 1
2 10.0 100.0 55.0 130.0 1
3 55-0 130.0 80.0 130.0 1
--------------------------
ISOTROPIC Soil Parameters
--------------------------
I Soil unit(s)specified
Soil Unit Weight Cohesion Friction Pore PreSSurc Water
Unit Moist Sal. Intercept Angle Parameter Constant Surface
No. (pct) (pct) (pst) (dc(-,) Ru (pst) No
-
I 1 15.0 125.0 200 0 32.00 .000 0 0
A critical failure Surface searching method_using a random
technique for generating CIRCULAR Surface,has been specified.
900 trial Surtaces kill be generated and anah zed
-
30 Surfaces initiate tom each of' 30 points equally spaced
along the ground Surface between x= 5.0 tt
and x= 15.0 ft
Fach Surface terminates bet%%een x= 50.0 it
and x= 80.0 ft
Unless further limitations�ccre imposed.the minimum ekcation
at%%hich a Surface extends is \ = 0 ft
* * * * * DEFAULT SECiAIENT LEN6 HI SELECTED BY'XSTABL
4 0 If line segments define each trial failure Surface
---------------------
ANGULAR RESTRICTIONS
---------------------
The tint segment ofeach tailure Surtace X011 be inclined
��ithin the angular range defined b%
1_o%\cr angular limit:_ -4511 degrees
Upper angular limit (slope angle-5;,m degree,
Factors of safety have been calculated by the
***** SIMPLIFIED JANBU METHOD
The 10 most critical of all the failure surfaces examined
are displayed below-the most critical first
Failure surface No. I specified by 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 10.17 100.11
2 14.17 100.06
3 18.16 100.33
4 22.12 100.91
26.02 101.81
6 29.84 103.00
7 33.55 104.50
8 37.12 106.29
9 4055 108.35
10 43.80 110.68
11 46.86 113.26
12 49.71 116.07
13 52.32 119.10
14 54.68 122.32
15 %.79 125.73
16 58.61 129.29
17 58.91 130.00
** Corrected J 1NBl FOS= 1.704 ** (Fo factor= 1-0611
Failure surface No 2 specified by 17 coordinate point;
Point x-surf N-surf
No. (a) (ft)
1 8.10 100.00
2 12.07 99.51
3 16.07 99.38
4 20.07 99.19
5 24.02 100.16
6 27.92 101.08
7 31.72 102.33
8 35-39 10391
9 38.91 105.81
I tl 42.25 108.02
11 45.38 1 10.51
12 48,28 113.26
13 50.92 116.26
14 53?9 119.49
15 55.'7 122.90
16 57.14 126.49
17 58.50 130.00
** Corrected JAN13L7 FOS= 1,722 ** (Fo factor= 1 068)
Failure surface No 3 specified b\ 16 coordinate points
Point \-surf c-surf
No (ft) (ft)
1 10.17 100.11
2 14.1(1 100.40
3 18 12 100.97
4 22-03 10L81
5 25.88 102.91
6 29.64 104.28
7 ;2 9 105.90
8 36 8 107.77
9 40 23 109.88
10 4,47 112 22
11 46 55 114.77
12 49.44 11754
1 52-14 120.49
Id 54.62 123.61
15 56.88 126.93
16 58.69 130.00
* Corrected JANBU FOS= 1.723 "' (Fo factor=1.053)
Failure surface No.4 specified b} 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 11.90 101.26
2 15.89 101.07
3 19.89 101.20
4 23.86 101.66
5 27.78 102.41
6 31.63 103.55
7 35.37 104.97
8 38.98 106.69
9 42.43 108.71
10 45.71 111.00
11 48.79 113.56
12 51.64 116.36
13 54.26 119.39
14 56.61 122.62
15 58.70 126.03
16 60.49 129.61
17 60.65 130.00
** Corrected JANBIJ FOS= 1.725 ** (Fo factor= 1.062)
Failure surface No 5 Specified by 18 coordinate points
Point x-surf c-surf
No. (lt) (ft)
1 6.38 100.00
2 10.34 99.47
3 14.34 99.27
4 18.34 99.39
i 22.31 99.84
6 2624 100.60
7 30.09 101.68
8 33.84 103.07
9 37.47 104.76
10 40.94 106.74
11 4425 10899
12 47.36 11150
13 5026 11426
14 52.93 117.24
15 55.34 120.43
16 57.49 123.80
17 59.36 127.34
18 60.50 130.00
** Corrected JANB('FOS= 1 728 "* (Fo factor= 1 066)
Failure surface No 6 specified by 17 coordinate points
Point c-Surf c-surf
No. (tt) (ft)
1 9.48 100.00
2 13.44 99.43
3 17.44 9923
4 21.43 99.42
i 25.39 99.99
6 29.28 100.93
7 3 3.0 6 l02 24
8 36.69 103.91
9 40.15 10091
10 43.41 108.24
11 46.42 11087
12 49.18 113.77
13 51.64 116.92
14 53.79 130.30
15 55.61 123.86
16 57.08 127.58
17 57.77 130.00
** Corrected JAN BU FOS= 1.729 ** (Fo factor=1.071)
Failure surface No.7 specified by 18 coordinate points
Point x-surf y-surf
No. (ft) (ft)
l 10.52 100.34
2 14.51 100.17
3 18.51 100.28
4 22.49 100.68
5 26.43 101.37
6 30.31 102.34
7 34.11 103.59
8 37.81 105.11
9 4139 106.90
10 44.83 108.95
11 48.11 111.23
12 51.21 113.75
13 5=4.13 116.49
14 56.84 119.43
15 59.33 122.56
16 6L58 125.87
17 63.59 12933
18 63.92 130,00
** Corrected JANBI'FOS= 1.729 ** (Fo factor=1.060)
Failure Surface No.8 specified b\ 18 coordinate points
Point x-surf s-surf
No. (ft) (tt)
1 6.38 100.00
2 10.35 99.5'
3 14.35 99.36
4 18.34 99 54
i 22.31 100.05
6 2622 100.88
7 30.05 102.04
8 3177 103.51
9 37.36 105-18
10 4079 10734
11 44.03 109.68
12 47.07 112,28
13 49.89 115.1'_
14 52.46 118.18
I5 54.77 121.45
16 56.80 12-1.89
17 58.54 1'_8 50
18 59.12 13000
**
Corrected JANBI FOS= 1.729 ** (Fo factor= 1 067)
Failure Surface No 9 specified bN 18 coordinate points
Point x-Surf -Surf
No. (ft) (t
1 9.14 1i�'00
2 1112 99.58
3 17.11 9945
4 21.11 90.68
5 21.08 loo 20
6 2899 10[03
7 32.83 W' 16
8 36.56 lo" 59
9 40.18 Ius?u
10 43-65 107.29
11 46.95 I,i0.55
1 2 50.06 1 1 2 06
13 52.97 114.80
14 55.66 117.77
15 58.11 120.93
16 60.30 124.28
17 62.22 127.78
18 63.22 130.00
** Corrected JANBU FOS= 1.729 ** (Fo factor= 1.064)
Failure surface No 10 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
l 12.59 101+72
2 16.57 101.42
3 20.57 101.46
4 24.56 101.85
5 28.49 102.58
6 32.34 103.66
7 36.09 105.06
8 39.69 106.79
9 43.14 108.82
10 46.39 111.14
11 49.43 113.74
12 52.24 116.60
13 54.78 119.68
14 57.05 122.98
15 59.02 126.46
16 60.63 130.00
** Corrected JANBL'FOS= 1.738 ** (Fo factor= 1-064)
** Out ofthe 900 Surfaces generated and anal%zed by SS I ABI- "
** 71 surfaces"ere found to have M1SLEADING FOS value; `*
The following is a summary of the TEN most critical surfaces
Problem Description : VanCleve 1.5 to 1 fill/cut to 30'
Modified Correction Initial Terminal :\ ailable
JANBU FOS Factor x-coord x-coord Strength
(It) (ft) (1 b)
I 1.704 1.061 10.17 58.91 3 803E+04
2, 1.722 1.068 8.10 58.50 4_'SUE+04
3 1.723 1.053 10.17 58.69 :.359F-04
4 1.725 1.062 1 1.90 60.65 4 015E+04
5_ 1.728 1.066 638 60 50 4 547E+04
6. 1.729 1.071 9.48 57.77 4340E+04
7- 1.729 1.0t)o 10.53 63-92 4667E+04
8 1.729 1+067 638 ;9.12 4260E+04
9. 1.729 1.064 9.14 63-„ 4 953E+04
10- 1.738 1.0x,4 12.59 60-63 4-055F+04
* * * END OF FILE:
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GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
12 May 2004
(Revised 21 June 2004)
Mr. and Mrs. Derek & Mona Van Cleve Job No. 04-8651
C/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Rear Yard Cut Slope Re-grading
Van Cleve Residence I
1972 Lake Drive
Encinitas, California
iDear Mr. and Mrs. Van Cleve:
In accordance with your request and our proposal of April 27, 2004, we are
providing general recommendations for re-grading of the existing upper cut slope
located in the northwest corner of your rear yard. As discussed in our letter of April
21, 2004, excavation for proposed yard area retaining walls resulted in temporary
cuts 6 to 8 feet in height along the west side of your home. We understand that
you wish to eliminate the higher, 8-foot cut that crosses the upper northwest corner
of your yard, if feasible, through a cut and fill grading operation. Based on our site
review as well as the site plan by Conway and Associates, Inc., it is our opinion that
minor cut and fill grading can be utilized to eliminate the temporary cut slope.
Refer to the Vicinity Map, Figure No. I, for the approximate site location.
We have provided Figure No. II to depict the areas of proposed cutting and filling
and Figure No. III to illustrate how such grading will eliminate the existing near-
vertical 8-foot slope. As shown on the figures, the upper cut slope should be re-cut
at approximately 1.0 horizontal to 1.0 vertical to approximately 9 feet in height and
the lower fill slope that will retain the lower half of the existing vertical cut can be
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech @ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
placed at approximately 2.0 horizontal to 1.0 vertical. The retaining wall design
values presented in our letter of April 21, 2004, are still valid for any wall location
with a level or gently sloping backfill. At locations where a 1.0:1.0 (horizontal to
vertical) slope to a maximum of 5 feet in height is to be retained, the wall should
be designed utilizing an equivalent fluid weight of 52 pcf.
Fill soils must be properly placed and compacted to a minimum degree of
compaction of 90 percent and be tested by our staff, in accordance with ASTM
D1557. This information should be provided to your civil engineers for inclusion on
the grading plan.
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, I C.
ie D. Reed, President cF'""�``J
ENGI^;EE R, %G
C.E.G. 999[exp. 3-31-05]/R.G. 3391
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- Van Cleve Residence
1972 Lake Drive
Encinitas, CA.
Figure No. I
Job No. 04-8651
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E"11 EOTE
CHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
21 April 2004
Mr. and Mrs. Derek & Mona Van Clev
c/o URBAN SOLUTIONS, INC. Job No. 04-8651
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Retaining Wall Design Geotechnical Criteria
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we have reviewed the existing excavations placed to accommodate
retaining wall construction along the western and north side rear yard of your
home. The property, currently improve with a two-story, single-family home, is
accessed by a concrete driveway off the west side of Lake Drive. The property is
further defined by APN 260-523-17.
Prior to our visit, we received a grading plan showing the proposed wall
improvements. The plan also showed the new pool and spa locations. Guniting of
the pool and spa had been completed at the time of our visit.
During the site review, our Certified Engineering Geologist noted that vertical cuts 6
to 8 feet in height, as well as initial footing excavations, had been placed along the
proposed wall alignment. The cuts expose dense, light brown, fine- to medium-
grained Torrey Sandstone of Eocene age. Due to the density and moderately
cemented nature of the Torrey Sandstone, the cuts are considered stable and
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX:(858)549-1604 • E-MAIL:geotech @Ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
acceptable as temporary construction slopes. Wall construction should, however,
proceed as soon as possible.
Although the existing footing excavations extend into the Torrey Sandstone, which
has excellent bearing characteristics, they appear to be undersized and will require
redigging after an engineered wall design is completed.
We recommend that the wall be designed utilizing footing foundations that extend
at least 18 inches into the undisturbed formational sandstone. At the
recommended depth, the footings may be designed for allowable bearing pressures
of 3,500 pounds per square foot (psf) for combined dead and live loads, and 4,700
psf for all loads including wind or seismic. The footings should, however, have a
minimum width of 12 inches. In order for us to offer an opinion as to whether the
footings are founded on soils of sufficient load bearing capacity, it is essential that
our representative inspect the footing excavations prior to the placement of
reinforcing steel or concrete. All loosened, disturbed formational soils should be
removed from the excavations to expose dense, undisturbed sandstone.
Lateral load resistance for the walls supported on footing foundations may be
developed in friction between the foundation bottoms and the supporting subgrade.
An allowable friction coefficient of 0.35 is considered applicable. An additional
allowable passive resistance equal to an equivalent fluid weight of 350 pounds per
cubic foot acting against the foundations may be used in design provided the
footings are poured neat against the adjacent undisturbed formational sandstone
materials. These lateral resistance values assume a level surface in front of the
footing for a minimum distance of three times the embedment depth of the footing
and any shear keys and are based on a factor of safety of 1.5.
The subject retaining walls consists of a combination of curvilinear layouts and
straight segments that terminate with right-angle return sections. The curvilinear
Orp
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 3
segments, as well as the straight segments extending 10 feet each way from the
angle points, should be designed for a restrained condition. The remainder of the
straight line segments may be designed for an unrestrained condition. We
recommend that the unrestrained (cantilever) wall sections be designed for an
equivalent fluid pressure of 35 pounds per cubic foot (pcf). Cantilever conditions
are defined as walls capable of horizontal movements of at least 0.005H at the top
of the wall, where H is the height of the wall, in feet. We recommend that the
restrained wall sections be designed for an equivalent fluid weight of 35 pcf plus an
additional uniform lateral pressure of 5H pounds per square foot, where H is the
height of the backfill above the top of the wall footing, in feet.
The preceding design pressures are based on sufficient drainage behind the walls to
prevent the build-up of hydrostatic pressures from surface water infiltration.
Adequate drainage may be provided by means of weepholes with permeable filter
material installed behind the walls.
Backfill placed behind the walls should be compacted to a minimum degree of
compaction of 90 percent using light compaction equipment. If heavy equipment is
used, the walls should be appropriately temporarily braced.
LIMITATIONS
Our assessment has been limited to providing the geotechnical criteria required for
design of the proposed western and northern yard area retaining walls. Verification
by our staff that footings have been properly cleaned of all loose material is
required prior to placement of steel reinforcing or concrete. It is not within the
scope of our assignment to address waterproofing or drainage behind the walls or
geotechnical conditions beyond the areas of the proposed western and northern
yard area improvements.
rpp.
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 4
If you have any questions concerning this matter, please contact our office.
Reference to our .lob No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
E ER D G,
G LESLIE 0G'i�,
Les Ie Reed, President RD,
r D
C.E.G. 999[exp. 3-31-05]/R.G. 3391 ru0. C?9
CERI IFIED
ENGINEERING
GEOLOGIST
Wm. D. Hes , G.E. FoF caL�
R.C.E. 26222/G.E. 396
QROf /0
�`►�OPV1D Ftl��
No.396
� CExp. 3/31/2006v
OTFCHN��'P�
FCA
�"
I j GEOTECHNICAL EXPLORATION, INC.
54N
SOIL&FOUNDATION ENGINEERING-- GROUNDWATER
HAZARDOUS MATERIALS MANA( EWNT,y ENGINEERING GEOLOGY
j
05 November 2004
Mr. and Mrs. Derek & Mona Van Cleve, - 3ob No. 04-8651
c/o URBAN SOLUTIONS, INC.
1049 Camino del Mar, Suite 11
Del Mar, CA 92014
Attn: Ms. Nancy Patterson
Subject: Proposed Cut and Fill Slop
Van Cleve Residence
1972 Lake Drive
Encinitas, California
Dear Mr. and Mrs. Van Cleve:
In accordance with the request of Nancy Patterson with Urban Solutions, Inc., on
your behalf, we are responding to recent comments by the Geotechnical Reviewer
for the City of Encinitas in his memorandum dated October 29, 2004. Although
revised grading plans are not available at this time, it is our understanding that the
current intent is to utilize 1.5 horizontal to 1.0 vertical cut and/or fill slopes.
Attached are mass stability calculations for 1.5 horizontal to 1.0 vertical cut and/or
fill slopes up to 30 feet in total height. The mass stability analysis, as well as the
attached surficial stability analysis, was performed using XSTABLE Version 5.2. In
our analysis we have utilized a cohesion value of 200 psf and an angle of internal
friction of 32 degrees to represent the saturated strength of the Torrey Sandstone
cut as well as the strength of well-compacted fill soils derived from the Torrey. In
the event imported fill soils are required, they should consist of silty to slightly
clayey sands that possess equal or greater strength than the Torrey materials. In
our opinion, a saturated depth of 2 feet is conservative for the proposed cut and/or
fill slopes. The results of our stability analyses are attached and indicate a factor of
safety in excess of 1.5 for both mass and surficial stability. The City, however, has
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech @Ixpres.com
Van Cleve Residence Job No. 04-8651
Encinitas, California Page 2
indicated that they will require that fill slopes steeper than 1.5 to 1.0 incorporate
geotextile reinforcing fabric to enhance the surficial stability. Accordingly, we
recommend that Mirafi 600x or equivalent reinforcing fabric be incorporated in the
fill slopes at 3-foot vertical intervals. The fabric should extend 3 feet horizontally
from the face of the slope.
If you have any questions concerning this matter, please contact our office.
Reference to our Job No. 04-8651 will help to expedite a response to your
inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
F ESS/p,,
` ID H�A��y
Wm. D.�Hesp r, Senior Geotechnical Engineer J: i
No.396
R.C.E. 26222/G.E. 396
C p. 3/31/2006
`r. F0 CHN�G���'
� OF CALW
XSTABL File:VAN1X 11-04-** 16:56
******************************************
* XSTABL
* *
* Slope Stability Analysis
* using the
* Method of Slices
*
* Copyright(C) 1992—96
* Interactive Software Designs,Inc.
* Moscow,ID 83843,U.S.A.
*
* All Rights Reserved
* *
* Ver. 5.200 96— 1358
Problem Description : VanCleve 1.5 to 1 fill/cut to 30'
-----------------------------
SEGMENT BOUNDARY COORDINATES
-----------------------------
3 SURFACE boundary segments
Segment x-left y-left x-right y-right Soil Unit
No. (ft) (ft) (ft) (ft) Below Segment
1 .0 100.0 10.0 100.0 1
2 10.0 100.0 55.0 130.0 1
3 55.0 130.0 80.0 130.0 1
--------------------------
ISOTROPIC Soil Parameters
--------------------------
I Soil unit(s)specified
Soil Unit Weight Cohesion Friction Pore Pressure Water
Unit Moist Sat. Intercept Angle Parameter Constant Surface
No. (pcf) (pcf) (psf) (deg) Ru (psf) No.
1 115.0 125.0 200.0 32.00 .000 10 0
A critical failure surface searching method,using a random
technique for generating CIRCULAR surfaces has been specified.
900 trial surfaces will be generated and analyzed.
30 Surfaces initiate from each of 30 points equally spaced
along the ground surface between x= 5.0 ft
and x= 15.0 ft
Each surface terminates between x= 50.0 ft
and x= 80.0 ft
Unless further limitations were imposed,the minimum elevation
at which a surface extends is y= .0 ft
***** DEFAULT SEGMENT LENGTH SELECTED BY XSTABL
4.0 It line segments define each trial failure surface.
---------------------
ANGULAR RESTRICTIONS
---------------------
The first segment of each failure surface will be inclined
within the angular range defined by:
Lower angular limit:_ -45.0 degrees
Upper angular limit:_ (slope angle-5.0)degrees
Factors of safety have been calculated by the
***** SIMPLIFIED JANBU METHOD
The 10 most critical of all the failure surfaces examined
are displayed below-the most critical first
Failure surface No. l specified by 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 10.17 100.11
2 14.17 100.06
3 18.16 100.33
4 22.12 100.91
5 26.02 101.81
6 29.84 103.00
7 33.55 104.50
8 37.12 106.29
9 40.55 108.35
10 43.80 110.68
11 46.86 113.26
12 49.71 116.07
13 52.32 119.10
14 54.68 122.32
15 56.79 125.73
16 58.61 129.29
17 58.91 130.00
** Corrected JANBU FOS= 1.704 ** (Fo factor= 1.061)
Failure surface No.2 specified by 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 8.10 100.00
2 12.07 99.51
3 16.07 99.38
4 20.07 99.59
5 24.02 100.16
6 27.92 101.08
7 31.72 102.33
8 35.39 103.91
9 38.91 105.81
10 42.25 108.02
11 45.38 110.51
12 48.28 113.26
13 50.92 116.26
14 53.29 119.49
1s 5537 122.90
16 57.14 126.49
17 58.50 130.00
** Corrected JANBU FOS= 1.722 ** (Fo factor= 1.068)
Failure surface No.3 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 10.17 100.11
2 14.16 100.40
3 18.12 100.97
4 22.03 101.81
5 25.88 102.91
6 29.64 104.28
7 33.29 105.90
8 36.83 107.77
9 40.23 109.88
10 43.47 112.22
11 46.55 114.77
12 49.44 117.54
13 52.14 120.49
14 54.62 123.63
15 56.88 126.93
16 58.69 130.00
** Corrected JANBU FOS= 1.723 ** (Fo factor=1.053)
Failure surface No.4 specified by 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 11.90 101.26
2 15.89 101.07
3 19.89 101.20
4 23.86 101.66
5 27.78 102.44
6 31.63 103.55
7 35.37 104.97
8 38.98 106.69
9 42.43 108.71
10 45.71 111.00
11 48.79 113.56
12 51.64 116.36
13 54.26 119.39
14 56.61 122.62
15 58.70 126.03
16 60.49 129.61
17 60.65 130.00
** Corrected JANBU FOS= 1.725 ** (Fo factor= 1.062)
Failure surface No.5 specified by 18 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 6.38 100.00
2 10.34 99.47
3 14.34 99.27
4 18.34 99.39
5 22.31 99.84
6 26.24 100.60
7 30.09 101.68
8 33.84 103.07
9 37.47 104.76
10 40.94 106.74
11 44.25 108.99
12 47.36 111.50
13 50.26 114.26
14 52.93 117.24
15 55.34 120.43
16 57.49 12180
17 59.36 127.34
18 60.50 130.00
** Corrected JANBU FOS= 1.728 ** (Fo factor= 1.066)
Failure surface No.6 specified by 17 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 9.48 100.00
2 13.44 99.43
3 17.44 99.23
4 21.43 99.42
5 25.39 99.99
6 29.28 100.93
7 33.06 102.24
8 36.69 103.91
9 40.15 105.91
10 43.41 108.24
11 46.42 110.87
12 49.18 113.77
13 51.64 116.92
14 53.79 120.30
15 55.61 123.86
16 57.08 127.58
17 57.77 130.00
** Corrected JANBU FOS= 1.729 ** (Fo factor=1.071)
Failure surface No.7 specified by 18 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 10.52 100.34
2 14.51 100.17
3 18.51 100.28
4 22.49 100.68
5 26.43 101.37
6 30.31 102.34
7 34.11 103.59
8 37.81 105.11
9 41.39 106.90
10 44.83 108.95
11 48.11 111.23
12 51.21 113.75
13 54.13 116.49
14 56.84 119.43
15 59.33 122.56
16 61.58 125.87
17 63.59 129.33
18 63.92 130.00
** Corrected JANBU FOS= 1.729 ** (Fo factor= 1.060)
Failure surface No.8 specified by 18 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 6.38 100.00
2 10.35 99.52
3 14.35 99.36
4 18.34 99.54
5 22.31 100.05
6 26.22 100.88
7 30.05 102.04
8 33.77 103.51
9 37.36 105.28
10 40.79 107.34
11 44.03 109.68
12 47.07 112.28
13 49.89 115.12
14 52.46 118.18
15 54.77 121.45
16 56.80 124.89
17 58.54 128.50
18 59.12 130.00
** Corrected JANBU FOS= 1.729 ** (Fo factor=1.067)
Failure surface No.9 specified by 18 coordinate points
Point x-surf v-surf
No. (ft) (ft)
1 9.14 100.00
2 13.12 99.58
3 17.11 99.48
4 21.11 99.68
5 25.08 100.20
6 28.99 101.03
7 32.83 102.16
8 36.56 103.59
9 40.18 105.30
10 43.65 10729
11 46.95 109.55
12 50.06 112.06
13 52.97 114.80
14 55.66 117.77
15 58.11 120.93
16 60.30 124.28
17 62.22 127.78
18 63.22 130.00
** Corrected JANBU FOS= 1.729 ** (Fo factor=1.064)
Failure surface No.10 specified by 16 coordinate points
Point x-surf y-surf
No. (ft) (ft)
1 12.59 101.72
2 16.57 101.42
3 20.57 101.46
4 24.56 101.85
5 28.49 102.58
6 32.34 103.66
7 36.09 105.06
8 39.69 106.79
9 43.14 108.82
10 46.39 111.14
11 49.43 113.74
12 52.24 1 16.60
13 54.78 119.68
14 57.05 122.98
15 59.02 126.46
16 60.63 130.00
** Corrected JANBU FOS= 1.738 ** (Fo factor= 1.064)
######f#k#####kk##k####kkf f######ff#k#####kk##k#f#######kk##k##f###k
** Out of the 900 surfaces generated and analyzed by XSTABL, **
** 71 surfaces were found to have MISLEADING FOS values. **
kk ##
The following is a summary of the TEN most critical surfaces
Problem Description : VanCleve 1.5 to 1 fill/cut to 30'
Modified Correction Initial Terminal Available
JANBU FOS Factor x-coord x-coord Strength
(ft) (ft) (lb)
I. 1.704 1.061 10.17 58.91 3.803E+04
2. 1.722 1.068 8.10 58.50 4.250E+04
1 1.723 1.053 10.17 580; 3.359Ey-04
4. 1.725 1.062 11.90 60.65 4.015E+04
5. 1.728 1.066 6.38 60.50 4.547E+04
6. 1.729 1.071 9.48 57.77 4.340E+04
7. 1.729 1.060 10.52 63.92 4.667E+04
8. 1.729 1.067 6.38 59.12 4.260E+04
9. 1.729 1.064 9.14 63.22 4.953E+04
10. 1.738 1.064 12.59 60.63 4.055E+04
*** END OF FILE
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