HomeMy WebLinkAboutCT 16-04; HIGHLAND VIEW HOMES; FINAL SOILS REPORT; 2018-03-23r
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AS-GRADED GEOTECHNICAL REPORT
Proposed Eight-Unit Residential Development
3758 -3794 Highland Drive
Carlsbad, California
HETHERINGTON ENGINEERING, INC.
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HETHERINGTON ENGINEERING, INC.
SOIL & FOUNDATION ENGINEERING • ENG INEER ING GEOLOGY • HYDROGEOLOGY
Carlsbad Coastal Views, LLC
3 7 5 8 Highland Drive
Carlsbad, California 92008
Attention: Mr. Brian Sullivan
Subject: AS-GRADED GEOTECHNICAL REPORT
Proposed Eight-Unit Residential Development
3758 -3794 Highland Drive
Carlsbad, California
References: Attached
Dear Mr. Sullivan:
March 23, 2018
Project No. 8047.2
Log No. 19732
In accordance with your request, we have performed geotechnical services in conjunction
with grading for the proposed construction of an eight-unit residential development at the
subject site. Our services consisted generally of the following:
• Geologic observation during remedial grading.
• Observation and density testing during the placement of compacted fill.
• Engineering and geologic analyses.
• Laboratory testing.
• The preparation of this report, which presents the results of our testing and
observations, and our conclusions and recommendations.
GRADING OPERATIONS
Grading was performed during the period January 2018 through February 2018. Grading
consisted generally of 2 to 3-feet of overexcavation of existing fill, alluvium and
disturbed terrace deposits down to approved terrace deposits and placement of compacted
fill to design site grades. The attached Plot Plan, Figure 1 indicates the approximate limits
of grading addressed by this report. The earthwork was performed by JC Grading, Inc.
utilizing grading plans prepared by Pasco Laret Suiter & Associates, dated December 12,
2017 (Reference 2).
5365 Avenida Encinas, Suite A • Carlsbad, CA 92008-4369 • (760) 93 1-1917 • Fax (760) 931-0545
333 Thi rd Street, Suite 2 • Lagu na Beach, CA 92651-2306 • (949) 715-5440 • Fax (760) 931-0545
www.hetheringtonengineering.com
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AS-GRADED GEOTECHNICAL REPORT
Project No. 8047.2
Log No. 19732
March 23, 2018
Page2
SITE PREPARATION
The site was cleared of existing surface obstructions, vegetation and debris, which were
disposed of offsite. Prior to fill placement, existing loose fill, alluvium and disturbed
terrace deposits were removed to expose competent terrace deposits. The depth and
extent of removals were determine in the field by an Engineering Geologist or Engineer
from this office. The approximate elevations of removal bottoms are shown on the
accompanying As-Graded Geotechnical Map, Plate 1. Alluvial soils were encountered
on the eastern portion of the site, trending north-south. Alluvial soils were removed with
removal depths up to 12-feet. In the areas where groundwater was encountered crushed
rock and/or broken concrete was used for stabilization prior to placing fill. Following
removals, the exposed terrace deposits were scarified to a depth of 6 to 8-inches, brought
to near optimum moisture conditions and compacted to at least 90-percent relative
compaction as determined by ASTM: D 1557.
SOIL TYPES
The soil utilized as fill consisted of on-site and import soils. The on-site soils were
derived from alluvium and terrace deposits. The on-site soils consisted generally of silty
sand. The import soils generally consisted of well graded sand with gravel and silty sand.
FILL PLACEMENT
Fill soils were placed in 6 to 8-inch thick, near horizontal lifts, moisture conditioned to
near optimum moisture content, and compacted to at least 90-percent relative compaction
as determined by ASTM: D 1557. Compaction was achieved by mechanical means using
a CAT D8N dozer, CAT D6H dozer, and a towed drum sheepsfoot roller. A water truck
was used for moisture conditioning.
Density tests were performed in accordance with ASTM: D 6938 (Nuclear 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 As-Graded Geotechnical Map, Plate 1. Maximum dry density/optimum
moisture content determinations are presented on the attached Summary of Maximum
Dry Density/Optimum Moisture Content Determinations, Table II.
CONCLUSIONS AND RECOMMENDATIONS
Based on our observations and the results of our testing, it is our opinion that the grading
of the site has been performed in general conformance with our recommendations and the
HETHERINGTON ENGINEERING, INC.
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REFERENCE
1) "Geotechnical Investigation, Proposed Eight-Unit Residential Development, 3758-
3794 Highland Drive, Carlsbad, California," by Hetherington Engineering, Inc., dated
September 30, 2016.
2) "Grading Plans for: Highland View Hornes", prepared by Pasco Laret Suiter &
Associates, dated December 12, 2017.
HETHERINGTON ENGINEERING, INC.
Project No. 8047.2
Log No. 19732