HomeMy WebLinkAboutCT 82-24; Sea Gate Village; Soils Report; 1991-12-17-
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ENGINEERING DEPT. LIBRARY
City of Carlsbad 2075 Las Palms Drive
Carlsbad, CA 92009-4859
qh3cl5B a+ ofi AS-GRADED GEOTECHl< CAL REPORT SURFICIAL SLOPE FAILURE REPAIR
Slope Adjacent to Building No. 27
North End of Sea Cliff Drive Sea Gate Village
Carlsbad, California
12-n - 41
m 323-M
7% 2.41.247
HETHERINGTON ENGINEERING, INC.
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HETHERINGTON ENGINEERING, INC.
GEOTECHNICAL CONSULTANTS
December 17, 1991 Project No. 384.2
Sea Gate Village
6555 Seagate Road
Carlsbad, CA 92009
Attention: Ms. Brenda Wright
Subject: AS-GRADED GEOTECHNICAL REPORT SURFICIAL SLOPE FAILURE REPAIR
Slope Adjacent to Building No. 27
North End of Sea Cliff Drive
Sea Gate Village Carlsbad, California
References: 1) "Surficial Slope Failure, Slope Adjacent to
Building No. 27, North End of Sea Cliff Drive, Sea
Gate Village, Carlsbad, California," by
Hetherington Engineering, Inc., dated March 12,
1991.
2) "Grading Plans for Seagate Slope Repair," by Hetherington Engineering, Inc., dated June 27,
1991.
Dear Ms. Wright:
In accordance with your request, we have performed geotechnical
services in conjunction with grading to repair a surficial slope failure at the subject site. The grading was performed in November
and December 1991. The purpose of the grading was to remove slope failure debris and replace the materials as compacted fill to pre- failure grades. Our services consisted of density testing and observation during grading, laboratory testing and the preparation of this report which presents the results of our testing and
observations, and our conclusions and recommendations.
SITE PREPARATION
Prior to grading, the site was cleared of surface obstructions and vegetation. The existing failure debris was removed to expose bedrock and/or undisturbed compacted fill. A fill key was
excavated at the bottom of the failed area. The key extended at least 2 feet into bedrock and/or undisturbed compacted fill and had
the
width of at least 10 feet. The approximate limits of the key and
approximate elevations of the bottom of key are indicated on
the accompanying Plot Plan, Plate 1.
5245 AVENIDA ENCINAS l SUITE G . CARLSBAD, CALIFORNIA 92006 l (619) 931.1917
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AS-GRADED GEOTECHNICAL REPORT SURFICIAL SLOPE FAILURE REPAIR
Project No. 384.2
December 17, 1991
Page 2
The soils exposed in the bottom of the key were scarified to a
depth of 6 to S-inches, brought to near optimum moisture conditions and recompacted to at least 90 percent relative compaction as
determined by ASTM: D 155744.
SLOPE TYPES
The soils utilized as fill consisted of the on-site materials
composed of the red and way to tan silty to clayey sand, and
imported material consisting of tan clayey sand with gravel.
FILL PLACEMENT
Fill soils were placed in 6 to B-inch thick, near horizontal lifts, moisture conditioned to near optimum moisture content, and
compacted by mechanical means to a minimum of 90 percent relative
compaction as determined by ASTM: D 155JA. The approximate limits
of fill are shown on the attached Plot Plan, Plate 1. Compaction was achieved by track rolling with a Caterpillar 935C Trak Loader and a sheepsfoot. Soil was moisture conditioned using a fire hose connected to an on-site fire hydrant.
Density tests were performed in accordance with ASTM: D 1556 (Sand- Cone Method). The results of the density tests are presented on the attached Summary of Field Density Tests, Table I. The approximate locations of the field density tests are indicated on the accompanying Plot Plan, Plate 1. Optimum moisture
content/maximum dry density determinations of soils utilized as
fill are presented on the attached Summary of Maximum Dry Density/Optimum Moisture Content Determinations, Table II.
CONCLUSIONS AND RECOMMENDATIONS
1. General
Based on our observations and the results of our testing, it is our opinion that the subject grading has been performed in general conformance with the recommendations contained in the referenced report and the requirements of the City of Carlsbad,
California.
2. The slope should be landscaped as soon as possible to minimize the potential for future erosion.
HETHERINGTON ENGINEERING, INC.
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AS-GRADED GEOTECHNICAL REPORT
SURFICIAL SLOPE FAILURE REPAIR Project No. 384.2 December 17, 1991
Page 3
3.
4.
If
Irrigated areas should not be over-watered. Irrigation should
be limited to that required to maintain the vegetation.
Additionally, automatic systems should be seasonally adjusted
to minimize over-saturation potential particularly in the winter (rainy) season.
Area drains should be periodically checked to verify they are not blocked and flow properly. This may be accomplished either
visually or, in the case of subsurface drains, placing a hose
at the inlet and checking the outlet for flow.
there are any questions regarding this report, please feel free to call. We appreciate this opportunity to be of service.
Sincerely,
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HETHERINGTON ENGINEERING, INC.
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TABLE I
SUMMARY OF FIELD DENSITY TESTS
Note: Test locations are shown on accompanying Plot Plan, Plate 1
Comments and Moisture Relative
Test Test Soil Test Elevation Dry Density Content Compaction
NO . Date Type (feet) (Pcf) (%) (%)
1 11/25/91 2 11/25/91 3 11/26/91 4 11/26/91 5 11/26/91 6 11/27/91 7 11/27/91 a 12/2/91
9 12/2/91 10 12/3/91
11 12/4/91 12 12/4/91
13 12/4/91 14 12/5/91 15 12/5/91
16 12/5/91
17 12/6/91 la 12/6/91
19 12/g/91
20 12/13/91
21 12/13/91
1
4
3 3
3
3
3 3
3
3
3
57.0, Key
58.0, Key
60.5
62.5
64.0
66.5
69.5
71.5 73.5
75.0
78.0
al.0 80.5 82.5 82.5
Retest of #14
82.5 Retest of #15
74.5, Slope Face 75.0, Slope Face Retest of #17
84.0
75.0, Slope Face Retest of #la
86.0, Berm
111.1 16.2 95
113.4 15.3 97
111.9 15.9 96
114.3 11.6 92
106.5 15.0 91
112.9 16.5 91
113.3 13.2 90
111.4 13.3 90
112.5 13.6 91
111.2 16.7 90
104.5 15.4 90
122.0 12.3 93
112.2 15.8 91
108.7 17.6 88
105.6 15.1 86
113.2 15.4
105.5
104.9
ill.8
ill.8
111.4
16.4 17.5
92
86 a5
15.9 15.9
13.6
91
91
91
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TABLE II
SUMMARY OF MAXIMUM DENSITY/OPTIMUM MOISTURE DETERMINATIONS
(ASTM: D 1557A)
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- Optimum Maximum Moisture Soil Density Content - Type Description (pcf) (%)
1 Gray to tan silty sand with clay 116.5 13.0 -
2 Gray to tan slightly clayey silty 124.0 11.5
sand -
3 Tan clayey sand with gravel (import) 123.0 12.0
- 4 Red-brown sand silty 131.5 9.0
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