HomeMy WebLinkAboutCDP 02-13; MCELROY RESIDENCE ADDITION; Coastal Development Permit (CDP)11/17/2005 12:41 FAX 760918679)^, RWR SAN UIEGO DIVISION Igl002
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SOJL & FOUNDATION ENGINEERING » GROUNDWATER
H-VTNRDOUS iV{Al-ER!AI..S MANAGEMENT » ENGINEERING GEOLOGY
25 September 2005
RWirHOM.E.S, INC. 3(ah 97-7189
2710 Loker Avenue West, Suite 350
Carisbad, CA 92008
Attn: Mr. Kbus Mendenhall
Subject: PssS£ESflSll211..SiilLMMlM§Sklil^^
Proposed Emerald Pointe Estates Subdivision
Northwest of Cobblestone Dilve, East of Laurel Tree RoacHAY 04 2/)/)/;
Carlsbad, Caiifomia
Dear Hr. Mendenhall: ' "'^"7TI
As requested, GBOtscimlcai ExpMrssdkm, Xmb, is herein providing post-tension
slab and foundation soil design parameters for the subject project. We understand
that post tension slabs are Intended for the harries of the proposed subdivision. Mr.
Ron Martin of Post--Ten.sion Design Unlimited has requested from us, with your
approval, to provide soil parameters for the design and construction plans of post-
tanslon slab foundation systems as an alternative to the previously recommended
conventional foundation system.
At this time, ws do nc-t know the expansion isidax of the soils that will cap tha
building, pad areas. However, for structural design and cost estimate preparation,
we provide the following soil parameters for different expansion indices. Category i
is for soils v/ith EI lass than 50. Category II .is for medium exp.ansive soils with EI
less than 90; Category III is for highly exparisive soils with EI greater than 90 but
less than 130, and Category. IV is for soils vvlth expansion indices higher than 130.
Preferably, the latter Category IV soils should be excluded from the pad areas cr
provided with a 4-foot cap of lower expansion solis as a cover. However^ if
7.420 TTfADS STOSCT » SAN DIESO. CA 92121 « CS53) 549-7222 I^AX; (85B) 549-1604 » E-MAii.; gaotechSSbcpfeS-Corn QJOP 0*2,-61 ^
139 f09X6l?SOS8 E.iSST 603S/S2/69 20 39Wd
11/17/2005 i;;:41 FAX 760918679 EWR SAN iriEGO DIVISION
Emerald Pointe Subdivision
Carisbad, California Job No. 97-7189
Paqe 2-
Categoi-y IV soils are found in tiiese areas after gnading is cornpleted, vva
recommend that Category IV values be used.
Th^,«xpansive soils should ba moistened and compacted during grading with a
moisture content at least 5 percerit over optimum. AFcer grading completion, the
soils should be kapt rnoist by Irriciatlng them v^lth sprinklers at least 10 rrifnutes
every 2 days. Soil moisture content should be vertned by our Raid representative
before placing the sand and moisture barrier layers and within 48 hours prior to
concrete placement.
Beanng values are 2,000 psf for footings in rill and 3,000 psf i'or fpodngs in
formatron-aJ soils. Please refer to our "Update Report of Prelirnlnan/ Geotechnical
Inv^jstigatlon" dated April 30, 2002, for other details in soil design parameter's.
The post-tension foundation systems shou,ki.be designed by the structural ??ng[neer
in accordance with post-tension slab design cxlterls of the Post-Tenslonlng Institute
or other acceptable method. The post-tension d.eslgn bas-ad on the PTI method
should incorporate the geotechnical parameters pressnted on the following table
entitled 'Tost-Tenslon Foundation System Design Criteria" for the particular
foundation categon/ designated.
posT-rmsioM FomDAiioBi SYSTSM. DESIGN CRTrER:m
.1. Thomthwaite Index .1. Thomthwaite Index -20 -20 "20 -20
2. Clay Type •• Montmorillonite . Yes Yes Ye-s Yes
; 3. ciay_Portion jMaximum) 30% 50% 60%-70%
i 4. Danth to Constant Soil Suction 5.0 ft' 7.0 ft 7.0 ft 7.0 ft'
1 5, So!} Sijctlon 3,G ft 3.5 ft 3.5 ft 3,6 ft
\ fs. Moisture Velocity 0,7 in/rno 0.7 in/mo 0.7 in/mo 0.7 in/rtio
139 £0 :2I S396/SZ:/B0
11/17/2005 12:4;.^ FM 7G0<)ia67g RWR SAM DTEGO DIVISION i]004
Emerald Pointe Subdivision
Carisbad, California
Job No. 97-7189
Page 3,
^nM::ia.?:'i:?=''SSj!iiptl^^
7. Edge Lift Moisture Variation
Dls.tance
2.5 ft 2.7 ft 2.S ft 3.0 ft
8. Edge Uft 0.25 In' 0.87 in 1.10 In ..-.l-SO in
6"o ft" 9. Center Lift Moisture Variation
Distance
4,8 ft 5,20 ft 5.8 ft
..-.l-SO in
6"o ft"
10. Center Lift 1.05 tn f 3,07 in 5.19 fn 6,76 in
11, Minimum Psirimeter Footing
Embedment Measured from Lowest
Adjacent Grade
1.05 tn
18" 24" 30"
The post-tension slab and foundation system rnay have different steel reinforcing
than the minimum ralnforcement foi" conventional slcdos Indicated in our soil repori;s.
However, Uva nevV system s'nould ba reinforced at least In accordanC'B witii the
standards of the industry. We recommend that perimeter and interior stiffenar
boams be used regardless of wlilph rriethod is used for the post--t.en5ion sSab
foundation system. Interior ribs or foundations should have tiie bottom of
excavation elevation at the same depth as the perimeter fbundatlons. Al! other
recornrnendations presarited in oiir April 30, 2002, soil report for this project remain
applicable unless superseded in writing by our firm. <?«<7fecfe«lc»l ^pi&ramn,
X»c. should be consulted to provide additional design parameters as required by the
Structural Ent^lneer.
During and after completion of grading, building pad soils should have EI tests
performed in typical soils aincount-sred in tha upper 4 feet of the fjuildsng pad areas
-and at finish grade. These tsats vM help classify a weighted e>cpansion index of tho
pad soils. The final foundation embedment shall be based on a v/eighted expansion
Index for the building pad areas.
\yQ 3SKld 139 tJBaTS'pssije £0:21 9mz/s.zm
11/17/2005 12:4;i FAX 760918679 RIYR SAN DIEGO OIVISION
Emerald Pointe Subdivision
Carlsbad, California Job No. 97-7189
Page 4
This opportunity to be of service is sincerely appreciated. Should you have any
que.stions regarding this matter, please contact the undersignad. Reference to our
3'Ob fig, •97-71B9 will help to expedite a response to your inquiries.
ft G s p e c tf u 11 y s u b rn i It e d,
r0 -"ii ?
Jaime A. Cerros, P.E.
R.C.E. 34422/G.E. 2007
Senior Geotechnical Engineer
cc: Addressee
, S f No. 002007' I S I
S(3 33Vcl 133 t^Baxsi^sssa £0:51 SBSS/ss/Ga