HomeMy WebLinkAboutCT 08-01; LA COSTA VIEWS; ADDENDUM TO LIMITED SITE INVESTIGATION UPDATE; 2007-11-06EAST COUNTY SOIL CONSULTATION
AND ENGINEERING, INC.
10925 HARTLEY ROAD, SUlTfr" CJ\fEED
SANTEE, CALIFORNIA 9071
(619) 258-790J/34, Jkl
Fax 258-79(O"
' YOFCARLSBAD
Mr. Steve Grady ,/ PLAN?K9PP 07
The Focus Group, LLC Project No.01-I 141fl1(1E)
7938 Ivanhoe Avenue, Suite "B"
La Jolla, California 92037
dJSubject: Addendum To Limite ite estigation Update
Two Proposed 8-Unit ential Buildings
North Side of La Costa Avenue, West of Romeria Street
City of Carlsbad, California
-,
U-RReferences: See Attached
Dear Mr. Grady: )ça
OL
In accordance with your request, this addendum has been prepared to address tie proposed
residential development at the subject site. We have reviewed the prelimiarfite-grading pin
for the referenced project, prepared by Masson & Associates, Inc. and dat1ei September 6, 2007.
It is our understanding that the new proposed construction will inc1ud>IW o4unit..resideitial Jk
buildings; both structures will be two-story over basement garages. As previously discussed, the
major factors affecting the proposed development are the stability of the adjacent 80-foot high
steep slope to the north, the expansion potential of the subgrade soils and settlement of poorly
compacted fill soils. Based upon these geotechnical constraints, the cast-in-drilled-hole caisson
and grade beam foundations recommended in the referenced soils report (Reference No. 5) are
still valid for the proposed construction. Caissons depths are anticipated to be approximatly 15 _k
feet below basement grade in the upperdand 20 feet iii'theower pad. Overexcavation and (f1
recompaction of floor slab areas toit minimum depth of: feet i recommended. The following
additional recommendations shoul&bç incorporated mthe design and construction
Permanent Slopes -
Permanent cut and fill slopes are anticipated to be less tad, 15 feet in height and may, b
constructed at a maximum slope ratio of 2:1 (hor. to vert. kto the heights indicated plans.
Slopes constructed in such a manner are anticipated to be grossly stable. Due t !legranular nature
of the on-site soil materials, surficial erosion is a common
resistant vegetation be planted on,these slopes as soon as practical to enhance théii stability.
THE FOCUS GROUP, LLC PROJECT NO. 01-1147H1(JE)
Temporary Slopes
For the excavation of basement garages or utility trenches, temporary vertical cuts to a maximum of
4 feet may be constructed in fill or natural soil. Any temporary cuts beyond the above height
constraints shouldbe shoredor further laidbackfollowinga 1:1 (hor.tovert. ) slope ratio. OSHA
guidelines for trench excavation safety should be implemented during construction.
Retaining Walls
Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 38 psffft (38
pcf EFP) for approved granular backfill and level backfill conditions. Where cantilevered walls
support 2:1 (horvert) sloping backfill, the equivalent active fluid pressure should be increased to 58
pcf. Cantilever walls subject to uniform surcharge loads should be designed for an additional
uniform lateral pressure equal to one-third (113) the anticipated surcharge pressure.
Restrained walls should be designed uti1i7ng an Ufl earth pressure of 60 psf7ft (60 pcf EFP)
for approved granular and level backfilL Restrained walls subject to uniform surcharge loads should
be designed for an additional uniform lateral pressure equal to one-half (112) the anticipated
surcharge.
East County Soil Consultation and Engineering, 'Inc. appreciates the opportunity to continue our
role as geotechnical consultant. If we can be of thither assistance, please do not hesitate to
contact our office.
Respectfully Submitted,
Mamadou Saliou Diallo
RCE 54071, GE 2704
MSDfmd
Cc: Addressee (3)
Dee Landers, Howes, Weiler & Associates (1)
Dan Masson, Masson & Associates (1)
2
THE FOCUS GROUP, LLC PROJECTNO. 01-1147H1(1E)
REFERENCES
I. "Limited Site Investigation Update, Proposed 26-Unit Residential Development, North
Side of La Costa Avenue, West of Romeria Street, City of Carlsbad, California", Project
No. 01-1247G1(1D), Prepared By East County Soil Consultation and Engineering, Inc.,
Dated March 5, 2007.
"Drainage Swale Clarification, Proposed Apartment Complex, Units No. 4 and 5, North
Side of La Costa Avenue, West of Romeria Street, City of Carlsbad, California", Project
No. 01-1247G1(1C), Prepared By East County Soil Consultation and Engineering, Inc.,
Dated February 17, 2004.
"Drainage Swale Assessment, Proposed 5-Unit Apartment Building, Lot 409, North Side
of La Costa Avenue, West of Romeria Street, City of Carlsbad, California", Project No.
01-1247G1(1B), Prepared By East County Soil Consultation and Engineering, Inc., Dated
December 8, 2001
"Addendum to Limited Site Investigation, Slope Stability Analysis and Drainage Swale
Location, Proposed 26-Unit Apartment Complex, 4 Vacant Lots, North Side of La Costa
Avenue, West of Romeria Street, City of Carlsbad, California", Project No. 01-
1247G1(1A), Prepared By East County Soil Consultation and Engineering, Inc., Dated
May 20, 2003.
5.. "Limited Site Investigation, Proposed 26-Unit Apartment Complex, 4 Vacant Lots, North
Side of La CostaAvenue, West of Romeria Street, City of Carlsbad, California", Project
No. 01-1247G1(1), Prepared By East County Soil Consultation and Engineering, Inc.,
Dated June 9, 2001.