HomeMy WebLinkAboutCT 07-05; LA COSTA GREENS NEIGHBORHOOD 1.03; INTERIM REPORT OF TESTING & OBSERVATION FOR RETAINING WALL; 2009-02-04GEOCON
INCORPORATED
Project No. 06403752-32A
February 4,. 2009
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EOTECHN!CAL CONSULTANTS )
CoiRich
4747 Morena Boulevard, Suite 100
San Diego, California 92117 . . .
Attention: Ms. Teri Shusterman
Subject: VILLAGES OF LA COSTA THE GREENS
NEIGHBORHOOD 1.03
VERDURA WALL NOS. A THROUGH D
INTERIM REPORT OF TESTING AND .QBSERVATION SERVICES FOR
SEGMENTAL (GEOSYNTHETIC REINFORCED) RETAINING WALL
References: 1. Update Geotechnical Report, Villages of La Costa, The Greens, Neighborhood 1.03,
Lots 1 through 38, Carlsbad, California, prepared by Geocon Incorporated, dated
February 7, 2008 (Project No. 06403-52-32): .
Consultation - Geotechnical Parameters for Segmental Retaining Wall, Villages of.
La Costa - The Greens, Neighborhood 1.03, Lots 1 through .38, Carlsbad,
California, prepared by Geocon Incorporated, dated 'October, 6, 2008 (Project
No. 06403-52-32A);
"erdura Segmental Retaining Walls, .La Costa Greens, Neighborhood 1.3, Carlsbad,
California, prepared by Southern California'Geotechnical, dated October 13, 2008,
(Project No: CT07-05, Drawing No. 457-8A).
Dear Ms. Shusterman:
In accordance with the request of your onsite superintendent, Mr. Larry Willis, we have provided
compaction jesting, and observation services during the construction of the segmental retaining wall
(SRW) atihe subject project. We will prepare a final report 'subsequent to the completion of the
remaining retaining walls. • ,
We, prformed our services on January 2, 2009 through January 21, 2009. The scope of our services
included:'
Performing testing and observation services during the installation of the subject wall.
Providing geotechni'cal consultation during wall construction.
6960 Flanders Drive • San Diego California 92121-2974 0 Telephone (858) 558.6900 • Fax (858) 558-6159
Performing laboratory tests on soil'used for wall backfill to aid in evaluating the compaction
characteristics (maximum dry density and optimum moisture content), shear strength,
Atterberg Limits, and sieve analysis..
Preparing this report of geotechnical services performed during wall backfill operations.
The Verdura segmental retaining walls with maximum height of approximately 7 feet were constructed
along the southern portion of the subject site. The wall contractor was Soil Retention Design
Incorporated. Prior to placing the wall units, a representative of Geocon Incorporated observed the
footing excavations along the base of the wall. Our observations indicate the soil conditions exposed in
the footings consisted of properly compacted fill or formational materials. The bearing strata at the
base of the excavations are considered suitable for the. support of the retaining wall and the soil
conditions encountered are consistent with those described in the referenced geotechnical report and
letter.
A wall drain, consisting of a 4-inch-diameter perforated drainpipe embedded in 3%-inch gravel and
wrapped in filter fabric (Mirafi 140N or equivalent), was installed at the base of the backcut along the
length of the wall and outlet at 50-foot intervals through the face of-the wall in substantial conformance
with the referenced wall plans. The drain should be connected to an approved outlet or drainage
system.
Backfill material was placedand compacted in layers to the design elevations. In addition, the geogrid
reinforcement was placed at locations in accordance with the referenced retaining wall plans. The
geogrid reinforcement consisted of Mirafi SXT.
During the backfill operations, we observed compaction procedures and performed in-place density
tests using a nuclear gauge in substantial conformance with ASTM Test Procedure D 2922. Results of
the field tests are summarized in Table I. In general, the in-place dry density test results indicate wall
backfill materials possess a dry density of least 90 percent of the laboratory maximum dry density near
to slightly above optimum moisture content at the locations tested.
We performed laboratory tests on the, material used for backfill Jo evaluate moisture-density
relationships, maximum dry density and optimum moisture content (ASTM D 1557), direct shear
(ASTM D 3080), Atterberg Limits (ASTM D 4318), and particle size/sieve analysis (ASTM D 422).
Laboratory test results are presented on Tables II through V.
From a geotechnical engineering standpoint, it is the opinion of Geocon Incorporated the Verdura
segmental retaining wall system was constructed in general conformance with the project plans and
specifications.
Project No. 06403-52-32A -2- February 4, 2009
Should you have any questions regarding this report, or if we may be of further service, please contact
the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Michael C. Ertwine Sad awn Weedon
Senior Staff Geologist EG 1778 GE 2714
MCE:AS:SW:dmc 0
(2) Addressee 'VO JA W
del) ColRich Job Site AU
Attention: Mr. Larry Willis R 01 CO cc 0 No. 2714
IL No. 1778 Exp. 06/30109 m
Project No. 06403-52-32A 0 -3- February 4, 2009
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Test No. Date Location
Elev.
or
Depth
t)
Curve
No.
Plus
3/4"
Rock
(%)
Field
Dry
Dens.
(pCf)
Field
Moist.
Cont.
Field
Rel.
Comp.
Reqd.
Re!.
Comp.
VW 1 01/02/09 Wall C - Footing Area 10+75 307 5 0 102.0 16.9 90 90
VW 2 01/02/09 Wall C -Footing Area ll+65 309 4 0 105.8 16.1 91 90
VW 3 01/05/09 WallC10+40 306 1 0 113.3 12.0 91 90
VW 4 01/05/09 WallC11+00 310 1 0 111.9 12.8 90 90
VW 5 01/05/09 Wall C11+55 310 I 0 112.6 14.3 91 90
VW 6 01/05/09 Wall C10+70
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
310 1 0 112.1 12.1 90 90
VW 7 01/06/08 Wall C11+75 311 1 0 111.8 11.6 90 90
VW 8 01/06/08 Wall Cl0+40 311 1 0 114.7 11.2 92 90
VW 9 01/06/08 Wall CIO+95 311 1 0 115.8 14.0 93 90
VW 10 01/06/08 Wall C11-s-35 312 1 0 116.0 12.0 93 90
VW iF 01/06/08 Wall C11+90 312 1 0 116.0 12.0 93 90
VW 12 01/06/08 Wall C10+55 310 1 0 113.0 12.4 91 90
VW 13 01/06/08 Wall C11+00 311 1 0 112.0 13.0 90 90
VW 14 01/08/09 Wall C10+95 311 1 0 113.4 15.0 91 90
VW 15- 01/08/09 WaliC 10+60 , 310 1 0 112.4 15.3 90 90
VW 16 01/08/09 Wall CII+45 313 1 0 111.6 12.8 90 90
VW 17 01/08/09 Wall C12+00 312 1 0 111.9 13.4 90 90
VW 18 01/09/09 Wall B - Footing Area 10+40 294 1 0 114.5 12.5 92 90
VW 19 01/09/09 Wall 10+65 292 1 0 111.8 13.3 90 90
VW 20 01/08/09 Wall B10+20 . 296 1 0 113.6 12.1 91 90
VW 21 01/12/09 WailA - Footing Area 10+60
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
293 1 0 111.5 12.6 90 90
VW 22 01/12/09 Wall A1O-i-30 297 1 0 109.1 13.6 88 90
VW 22A 01/12/09 Wall A1O-i-30 297 1 0 113.2 12.9 91 90
VW 23 01/12/09 Wall Ai0+60 294, 1 0 111.9 11.7 90 90
VW 24 01/12/09 Wall A10+35 299 1 0 112.4 14.1 90 90.
VW 25 01/13/09 Wall A10+55 294 1 0 111.8 11.6 90 90
VW 26 01/13/09 Wall AIO+20 301 1 0 115.0 12.4 93 90
VW 27 01/13/09 Wall A10+60 302 1 0 112.2 13.7 90 90
VW 28 01/13/09 Wall B- Footing Area l0+35 283 1 0 113.6 12.1 91 90
VW 29 01/13/09 Wall 10+15 286 1 0 114.7 11.8 92 90
VW , 30 01/14/09 Wall B 10+25 285 1 0 107.4 13.0 86 90
VW 30A 01/14/09 Wall 10+25 .285 1 0 112.5 13.8 91 90
VW 31 01/14/09 Wall 10+05 285 1 0 112.8 12.4 91 90
VW 32 01/14/09 Wall BIO+30 286 1 0 112.9 12.8 91 90
VW 33 01/14/09 Wall 10+15 . 287 1 0 112.4 12.4 90 90
VW 34 01/14/09 Wall B10+30 288 1 0 112.9 12.8 91 90
VW 35 01/15/09 WailD - Footing Area 10+10 299 1 0 113.1 13.2 91 90
VW 36 01/15/09 Wall D- Footing Area lO+15 301 1 0 111.7 11.8 90 90
VW 37 01/16/09' Wall. D- Footing Area lO+20 301 2 0 117.4 10.2 92 90
VW 38 01/16/09 Wall D10+45 303 2 . 0 118.6 11.3 93 90
VW 39 01/16/09 Wall Dl0+25 303 1 0 113.3 13.1 91 90
VW 40 01/16/09 Wa1lD10+40 304 1 0 111.9 12.6 90 90
VW 41 01/16/09 Wall D10+80 305 2 0 115.9 11.3 91 90
VW 42 01/16/09 Wall D11+20 307 1 0 114.7 11.4 92 90
VW 43 01/16/09 Wall D10+35 305 1 0 112.0 12.5 90 90
Project No. 06403-52-32B February 4, 2009
TABLE!
SUMMARY OF FIELD DENSITY TEST RESULTS
Elev. Plus Field Field Field Reqd.
or 3/4 Dry Moist. Re!. Rel.
Depth Curve Rock Dens. Cont. Comp. Comp.
Test No. Date Location (t) No. (%) (D
VW 44 01/20/09 Wall D 10+55 306 1 0 107.4 12.3 86 90
VW, 44A 01/20/09 Wall D10+55 306 1 0 113.4 12.9 91 90
VW 45 01/20/09 Wall 11+00. 308 2 0. 116.1 11.8 91 90
VW 46 01/20/09 Wall D11+30 309 2 0 114.7 13.2 90 90
VW 47 01/20/09 Wall D10+85 309 2 0 114.9 12.5 90 90
VW 48 01/21/09 Wall DIO+30
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
306 1 0 111.5 13.0 90 90
VW 49 01/21/09 Wall D!l+05 310 1 0 112.8 11.5 91 90
VW 50 01/21/09 Wall 16+55 309 1 . 0 112.0 12.0 90 90
.VW 51 01/21/09 Wall Dl0-i-95 312 1 0 .114.0 13.9 92 90
VW 52 01/21/09 Wall D11+25
.
312 2 0 118.2 10.6 93 90
C
/
Project No. 06403-52-32B February 4, 2009
TABLE I -
EXPLANATION OF CODED TERMS
- TEST SUFFIX
A, B, C,. . . : Retest of previous density test failure, following moisture conditioning and/or recompaction.
- TRll(E-OUT—
Fill in area of density test failure was removed and replaced with properly compacted fill soil.
- PREFIX CODE DESIGNATION FOR TEST NUMBERS
VW - Verdura Wall Backfill
-CURVE NO.
Corresponds to curve numbers listed in the summary of laboratory maximum dry density and optimum
moisture content test results table for selected fill soil samples encountered during testing and observation.
- ROCK CORRECTION
For density tests with rock percentage greater than zero, laboratory maximum dry density and optimum
moisture content were adjusted for rock content. For tests with rock content equal to zero, laboratory
maximum dry density and optimum moisture content values are unadjusted.
TYPE OF TEST
SC: • Sand Cone Test (ASTM D1556)
NU: Nuclear Density Test (ASTM D2922)
OT: Other
- ELEVATION/DEPTH
Test elevations/depths have been rounded to the nearest whole foot.
- LOCATION DESCRIPTION
(IP): Indicates in-place tests Where (IP) appears in the location description, the compaction procedures
were not observed by a representative of Geocon. Tests were taken at the surface or in test pits after
placement of the fill. The results of these tests are indicative of the relative compaction at the location of
the test only and may not be extrapolated to adjacent areas. Geocon has no opinion regarding the relative
compaction of fill in adjacent areas.
Project No: 06403-52-32B
0
February 4, 2009
TABLE II
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND
OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D1557
Sample No. Description Maximum Dry
Density (pcf)
Optimum
Moisture
Content (%)
1 Olive brown, Silty SAND 124.2 11.0
2 Brown, Clayey SAND 127.4 10.2
4 I Light yellowish brown, Silty SAND 116.5 13.3
5 Light brown to reddish brown , Silty to Clayey SAND 113.4 15.0
TABLE III
SUMMARY OF LABORATORY DIRECT SHEAR TEST RESULTS
ASTM D3O8O
Sample No. Dr y Density
(pet)
Moisture Content (°) Unit Cohesion
(psf)
Angle of
Shear Resistance
(degrees) Initial Final
1 .110.1. 12.5 I 23.4 270 32
2 114.2 10.4 18.4 225 33
Samples were remolded to approximately 90 percent of laboratory maximumdry density at near optimum moisture
content. -
- . TABLE IV
SUMMARY OF LABORATORY ATTERBERG LIMITS TEST RESULTS
ASTM 04318
Sample No. Liquid Limit Plastic Limit Plasticity Index
1. .37 18 19.'
2 . 112 36 18
TABLE -
SUMMARY OF LABORATORY PARTICAL SIZE/SIEVE ANALYSIS
TEST RESULTS ASTM D 422
Sieve Size Sample No. 1
(% passing)
Sample No. 2
(% passing)
1 inch 100 . . 100
3/4 inch 99 98
3/sinch 99 95
No.4 . 99 94
No.8 99 89
No. 30 . 90 . 78
No. 50 84 68
No. 200 34 34
i Project No. 06403-52-32A . February 4, 2009