HomeMy WebLinkAboutTract Map 3334 Lot 23 Additional Geotechnical Investigation 11-11-97
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John R. B4erh.~
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November 11, 1997
The Spanos Companies
5029 La Mart Drive, Suite A-2
Riverside, California 92507
Rpt. No.: 5118
File No.: S-8939
Attention: Jack Sorenson
Subject: Proposed Tuscany Ridge Apartments, Margarita Road, East of Moraga Road,
Temecula, California; Slope Stability Analyses
Reference: Additional Geotechnical Investigation, John R. Byerly, Inc., Rpt. No. 4976,
September 29, 1997
Gentlemen:
. The referenced report presents the results of our supplementary geotechnical investigation for
the Tuscany Ridge Apartments in the city of Temecula. As part of the proposed development,
a 2:1 (H:V) fill slope up to 38 feet in height is planned for the southeasterly property perimeter.
It is proposed to construct this slope without the installation of a mid-slope drainage terrace.
Required at this time are surficial and gross slope stability analyses for the proposed slope.
In order to obtain. strength parameters for the stability analyses, soil samples encountered
during the referenced investigation were remolded to 90 percent relative compaction (ASTM D
1557). Subsequent to saturation, direct shear testing was conducted on these samples. The
results of the direct shear testing are presented on Enclosure 1.
In order to evaluate the gross stability, static and psuedo-static (seismic factor of 0.15g) slope
stability analyses for this slope using the Bishop's Method of Slices and the Geosoft STABRG
computer program were conducted. The results are presented on Enclosure 2. The factor of .
safety against gross failure exceeds 1.5. A surficial slope stability analysis was also performed.
As shown on Enclosure 2, this analysis revealed a safety factor of 1.7.
It is our opinion that these safety factors reveal that the proposed slope will be stable with
respect to gross and surficial stability.
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Slopes should be constructed no steeper than 2:1 (H:V). Fill slopes should be overfilled during
construction and then cut back to expose fully compacted soil. A suitable alternative would be
to compact the slopes during construction, and then roll the final slope to provide a dense,
erosion resistant surface.
GEOTECHNICAL ENGINEERS. TESTING AND INSPECTION
2257 South Lilac Ave, Bloomington, CA 92316-2903
Bloomington (909) 877-1324 Riverside (909) 783-1910 Fax (909) 877-5210
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The Spanos Companies
November 11, 1997
Page 2
Rpt. No.: 5118
File No.: S-8939
The surface of the site should be graded to provide positive drainage away from the structures
and slope faces. A berm or brow ditch should be constructed at the top of all slopes that will
contain the water flow and control the surface run-off. Drainage should be directed to
established swales and then to appropriate drainage structures to minimize the possibility of
serious erosion. Slopes constructed with soils that have a high erosion potential should be
planted as soon as practical subsequent to construction. It is recommended that plants used
for slope cover require a minimal use of irrigation.
We appreciate this opportunity to be of continuing service. Should there be questions, please
do not hesitate to contact this office.
Respectfully submitted,
JOHN R. BYERLY, INC.
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. Glenn S. Fraser, Civil Engineer
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John R. Byerly, Geotechnical Engineer
President
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Enclosures: (1) Direct Shear Test Data
(2) Slope Stability Analyses
Copies: (3) Client
(1) Rick Engineering
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DIRECT SHEAR TESTS
(Remolded to 90 Percent Relative Compaction)
Soil Type
Angle of Internal
Friction {OJ
Cohesion
(PSF)
Silty fine to coarse sand with clay
Silty fine to medium sand
30
29
250
180
Enclosure 1
Rpt.No.: 5118
File No.: S-8939
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I 151.6 9U 300.0 160.0 3.035 1.615
2 20,5 au JIO.o 160,0 !.5H 2.168
1 W.2 8U ]20,0 160.0 2.1l! 1,9H
I m.o au m.D 160.0 \.863 J,113
; 239.9 19,9 HO.O 160.0 1.711 1.616
6 m.o 19.0 350,0 160.0 I.m 1.111
1 HO.O 10.0 HO.O 110.0 Lm 1.60
, 2J;.8 8U HO.O 150.0 1.738 l.SH
, 239.3 1U m.o 16n.D 1.76D LOil
10 Ho.O 15,0 Ho.O 165.0 1.70 \.622
" 140.8 ~O. a W.O 160.0 !,1H 1.612
" 2JU H.9 HO.D 155.0 1.731 1.621
" 239.3 8U 315.11 155.0 1.136 Utll
" HO.? 85.1 uu 155.0 1.181 1.660
" m.8 ~u HO.o m.o 1.138 J.6H
16 2J9.1 19.1 W.O 160.0 I.m 1.663
11 W.8 80.8 m.o 160.0 1.1H UH
" !l0.6 iO.6 m.o 150.0 1.800 1.613
" m.l 8U W,O 150,0 1.TH 1.631
2' m.o 89.0 350.0 150.0 1.192 1.111
!I m.3 ~c.J 30.0 11S.0 l.1U I.6H
12 m.o 9LO 350.0 W.o 1.163 I.m
!3 !JU 9U HO.O [0.0 1.150 1.6SI
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25 139.0 89.0 m.o 150.0 1.192 1.111
" m.8 n.8 JU.o 150.0 I.7n I.6H
!I 139.1 99.1 HO.O m.o 1.161 1.613
n m.o 99.0 m,o HO.O ].7CI 1.669
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Enclosure 2
Rpt.No.: 5118
File No.: S-8939
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