HomeMy WebLinkAboutCT 04-26; ROBERTSON RANCH PA 16, 17 & 18; GEOTECHNICAL UPDATE; 2011-01-31() Geotechnical . Geologic . Coastal' flironmental
5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915wwSoilThC.00m
January 31, 2011
W.O. 5949-5SC
Brookfield Homes
12865 Pointe Del Mar, Suite 200
Del Mar, California 92014
Attention: Ms. TeriMcHugh
Subject: Geotechnical Update for Planning area 16, Production Phase 4, Lots 166
through 172, and 180 through 183, Robertson Ranch, East Village, Carlsbad
Tract 04-26, Drawing 453-8C, City of Carlsbad, San Diego County, California
References: 1. "Supplemental Discussion of Slab Subgrade Pre-Wetting, Planning Area 16 of Robertson
Ranch, City of Carlsbad, California," W.O. 5949-C-SC, dated August 17, 2010, by GeoSoils,
Inc.
"Discussion of Building Slab Subgrade Pre-Wetting Plan ningAreaJ6 of_Robertson
Ranch, City of Carlsbad, California," W.O. 5949-C-SC, edOctobef200byGeoSoils,
"Report of Rough Grading, Planning Area 16 of Robertson Ranch, East Village (Lots 44
through 63, 89 through 99, 117 through 140, and 160 through 189), Carlsbad Tract 04-26,
Drawing453r8ACarlsbad San Diego County California" W.O. 5353-B1-SC dated
GeoSoils, Inc.
Dear Ms. McHugh:
In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the referenced reports
and plans with respectto as-graded site conditions and has prepared this summary update
report. Grading and processing of original ground within the subject building pads was
observed and selectively tested by a representative of GSI during the earthwork phase of
development for the subject property (see Reference No. 3). Based on our observations
and testing, the subject lots are considered suitable for their intended residential use.
Geotechnical observations and testing completed by this office during site grading are
summarized in Reference No. 3. As of this date, the site has not changed significantly
since the completion of grading and the issuance of Reference No. 3; thus, the findings,
conclusions, and recommendations presented in that report are generally considered valid
and applicable with respect to the construction and development of the subject building
pads. Based on the duration of time following pad completion, pre-wetting, and/or surficial
processing is recommended, as indicated in Reference No. 1 and Reference No. 2.
David W. Skelly %
47 Civil Engineer, RC ."
Respectfully sut
GeoSoils, I
Robert G. Crism
Engineering Geo
LIMITATIONS
Inasmuch as our study is based upon our review, engineering analyses, and laboratory
data, these conclusions and recommendations are professional opinions. These opinions
have been derived in accordance with current standards of practice, and no warranty is
express or implied. Standards of practice are subject to change with time. GSI assumes
no responsibility or liability for work or testing performed by others, or their inaction, or
work performed when GSI Js •not requested to be onsite to evaluate if our
recommendations have been properly implemented. Use of this report constitutes an
agreement and consent by the user to all the limitations outlined above, notwithstanding
any other agreements that may be in place. In addition, this report may be subject to
review by the controlling authorities.
The opportunity to be of service is greatly appreciated. If you have any questions, please
do not hesitate to call our office.
RGC/DWS/J PF/jh
Distribution: (4) Addressee
Brookfield Homes W.O. 5949-B-SC
Production Lots Ph. 4, PA-16, Robertson Ranch January 31, 2011
File: e:\wp9\5900\5949b. pal 6.gu4 Page 2
GeoSoils, Inc.
12/13/2010 12:13 FAX 17606342415 BURTECH iJ 015
12/13/2618 11:62 6195615526 NORTH COUNTY GUNITE PAGE 15/15
ibl
I).r.I%.lir 1000 air-eicr&t1ning
'Willix(VIV i.. fully effxtivc and
tsiitp.ttihle iii iiiwrct with other
.WmINrtIr. EACH ADMIX-
TURE, IIUWIVER. SHOULD
(* Al)I)Itfl TO THLCON-
(:RlFl SlI';\RATEL.Y.
Thery is n, srindard addition rate
Ior Daravair 10(R) air-entraining
&iJiuixrairi. Tlw •amounc to he
d will b..piid upon the
iinutint I if air required for lob
usually in the range of
4 to H,. Typical fictors which
might iii fluncc the amount of air-
en(rulniug admixture required
arc, rciup.r&inirc, cement, sand
grudatkiii and the use of extra
tIne mnareilals such as fly ash and
n,Icrmbsilid. Typical Daravair
I 01)4) addition rates range from
30 to 24)4) in 11100 kg (141 to
.; 1 oV1100 Ills) oFceiient.
lntsrIng of concrete should he
perfornicd to comm firm dosage
rares reqL;ired to achieve desired
omicrery pirfnrniance.
The atr•cntralnlngcapactry of
Daravair 1000 is usually
increased when other concrete
admixtures are contained in the
concrete, particularly water-
reducing admixtures and water-
reducing retarders. This may
allow up to a two-thirds reduc-
tion in the amount of Daravair
1000 required.
MI.', Adjustrnnt
Entrained air will increase the
volume of the concrete making it
necessary to adjust the mix pro-
portions to maintain the cement
factor and yield. This may be
accomplished by a rcductlon in
water requirement and aggregate
convent.
-. .ri&i;ing Equipment
A complete line of accurate auto-
matic dispensing equipment is
available. Thcsc dispensers can
he located to discharge into
the water line, the mixer, or on
the sand.
Packaging
Daravair 1000 air-entraining
admixture is available in bulk,
delivered by mercrcd tank trucks
and in 210 L (55 gal) drums.
Daravair 1000 will freeze at
about -1°C (30°F) but its air-
entraining properties are com-
pletely restored by thawing and
thorough mechanical agitation.
ArchltRcts' Specifications
Concrete shall be air entrained
concrete, containing 4 to 8%
entrained air. The air contents in
the concrete shalt be determined
by the pressure method (ASTM
Designation C 231) or volumetric
method (ASTM Designation C
173). The air-entraining admix-
ture shall be a completely neutral-
ized rosin solution, such as
Daravair 1000, as manufactured
by Grace Construction Products,
or equal, and comply with
standard specification for air-
entraining adrnixvures (ASTM
Designation C 260). The air-
entraining admixture shall be
added at the concrete mixer or
batching plant at approximately
30 to 200 mL/100 kg (½ to
3 fl oz/100 Ibs) of cement, or In
such quantities as to give the
specified air contents.
North Amertcen Customer Carvica: 1477.4A0.MIX1 (1.971-4234491)
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12/13/2010 MON 11:00 (TX/RI NO 53451 9 015