HomeMy WebLinkAboutCT 02-19; BRESSI RANCH PA 11; AS-GRADED GEOTECHNICAL COMPLETION LETTER; 2011-03-08cT
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Leighton and. Associates, Inc.
A LEIGHTON GROUP COMPANY
March 8, 2011
(Revised March 16, 2011)
Project No. 042458-003
To: Manolia Partners, LLC
1094 Cudahy, Suite 212
San Diego, California 92110
Attention: Mr. John Colucci
Subject: As-Graded Geotechnical Completion Letter for Lots 7 and 13, Magnolia Estates,
Bressi Ranch, PA- 11, Carlsbad, California
References: Leighton, and Associates, 2010, Geotechnical Update Letter, Magnolia Estates,
Bressi Ranch, PA-11, Carlsbad, California, Project No. 042458-001, dated
February 10, 2010
Leighton and Associates, 2004, As-Graded Report of Rough and Fine Grading,
Lots. 1 through 25, Planning Area PA- 11, Bressi Ranch, Carlsbad Tract No. 00-
06, Carlsbad, California, Project No. 971009-014, dated October 8, 2004
In accordance with your request and authorization, Leighton and Associates, Inc. (Leighton) has
performed geotechnical observations and testing services during the fine grading (i.e., restoration
or re-processing the residential building pads) of Lots 7 and 13 at Magnolia Estates, Bressi Ranch
(PA-i 1), in Carlsbad, California. This letter summarizes our geotechnical observations, field and
laboratory test results, and the geotechnical conditions encountered during the grading activities.
The fine grading operations were performed by C&C Equipment Rental, between February 23
and March 4, 2011. During the grading, geotechnical observation and testing was performed by a
representative of Leighton. Based on our observations and testing services, it is our professional
opinion that the subject pad grading was performed in general accordance with the
recommendations of the project geotechnical report and update letter (Leighton, 2004 and 2010).
3934 Murphy Canyon Road, Suite B205 • San Diego, CA 921234425
858.292.8030 • Fax 858.292.0771
042458-003
and recommendations made during the course of grading. The geoteclmical conditions
encountered during grading were generally as anticipated.
In summary, the fine grading for the building pads consisted of clearing and grubbing of weeds,
and re-processing the upper 1-foot of on-site soils. The surface soil was scarified a minimum
depth of 12 inches, moisture conditioned to above the optimum moisture content, and compacted
to at least 90 percent relative compaction based on ASTM Test Method D1557. In addition, the
existing driveway approach on Lot 13 was relocated. The previous driveway area was filled in
with approximately 7 to 8 feet of fill. The fill was placed and compacted in 6 to 8 inches lifts. All
fill soils were compacted to a minimum 90 percent relative compaction (based on ASTM Test
Method Dl 557) with moisture contents above the optimum moisture content. A summary of the
field density tests is attached. Note that the soil on Lots 7 and 13 were previously tested for
expansion potential and determined to be a medium (Leighton, 2004). In addition, soluble sulfate
content tests of representative finish grade soils on building pads were previously performed in
accordance with ASTM Test Method D4829 and standard geochemical methods, respectively. The
laboratory test results indicate the building pads finish grade soils possess severe and moderate
soluble sulfate content, Lot 7 and Lot 13, respectively (Leighton, 2004).
It is our professional opinion that the building's pad is suitable for the intended use provided the
recommendations included in the project geotechnical report and update letter (Leighton, 2004
and 2010) are incorporated into the design and construction of the structures and associated
improvements.
Please note that the presence of our field representative at the site was intended to provide the
owner with professional advice, opinions, and recommendations based on observations of the
contractor's work. Although the observations did not reveal obvious deficiencies or deviations
from project specifications, we do not guarantee the contractor's work, nor do our services relieve
the contractor or his subcontractor's work, nor do our Services relieve the contractor or his
subcontractors of their responsibility if defects are subsequently discovered in their work. Our
responsibilities did not include any supervision or direction of the actual work procedures of the
contractor, his personnel, or subcontractors. The conclusions in this report are based on test results
and observations of the grading and earthwork procedures used and represent our engineering
opinion as to the compliance of the results with the project specifications.
-2- Leighton
042458-003
If you have any questions regarding our letter, please do not hesitate to contact this office. We
appreciate this opportunity to be of service.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
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NO. 2457
CERTIFIED
(( NNG INEERING
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Mike D. Jensen, CEG 2457
Project Geologist
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William D Olson, RCE 45283
Associate Engineer
Attachment: Summary of Field Density Tests
Distribution: (3) Addressee
Leighton
S
SUMMARY OF FIELD DENSITY TESTS
Test Test Test Location Test Soil Dry Density Moisture (%) Relative (%)
No. I Date Of Lot # Elev (ft) Type Field Max Field Opt. Compaction Remarks
• 2/24/11 CF Lot 13 (D-W) 307.0 27 113.9 118.5 16.0 14.0 96
2 2/24/11 CF Lot 13(D-W) 309.0 27 111.9 118.5 15.6 14.0 94
3 2/24/11 FG Lot 7(Pad) 0.0 27 111.4 118.5 14.2 14.0 94
4 2/24/11 FG Lot 7(Pad) 0.0 27 109.7 118.5 14.9 14.0 93
5 2/24/11 FG Lot 7(Pad) 0.0 27 110.6 118.5 15.1 14.0 93
6 2/25/11 CF Lot 13(D-W) 310.5 17 102.8 114.0 15.3 14.5 90
7 2/25/11 CF Lot 13(D-W) 312.5 17 106.9 114.0 15.2 14.5 94
8 3/4/11 FG Lot 13(D-W) 0.0 27 107.7 118.5 14.8 14.0 91
9 3/4/11 FG Lot 13 (Pad) 0.0 27 112.7 118.5 16.4 14.0 95
10 3/4/11 FG Lot 13 (Pad) 0.0 27 109.0 118.5 14.9 14.0 92
11 3/4/11 FG Lot 13 (Pad) 0.0 27 109.6 118.5 15.4 14.0 92
Project Number: 042458-003 0 Project Name: Bressi Ranch/PA-1 1
Project Location: 0
Client: 0 Page 1 of 1 . .
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