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Home My WebLink AboutCT 02-07; EMERALD POINT ESTATES; POST TENSION SLAB SOIL DESIGN PARAMETERS; 2005-09-26RWR SAN D~EGO DIVISION • 141 002 GEOTECHNICAL EXPLORATION, INC. SOIL & FOUNDATION ENGINEERING • GROUNDWATER HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY 26 September 2005 RWR HOMES, INC. 2710 Loker Avenue West, Suite 350 Carlsbadr CA 92008 Attn: Mr. Klaus Mendenhall Job No. 97-7189 ~CE117Je1) Subject: . MAY 04 2 Post-Tension Slab Soil Design Paramewl '006 Proposed Emerald Pointe Estates SubdivisIon ENGIN€S Northwest of Cobblestone Drive, East of Laurel Tre~~~"'4:!ff"G Carlsbad, California . I ' .:' "j ~ Dear Mr. Mendenhall: As r-equested, GootechniCll!Ji Exploration ... Inc. is herein providrng post-tension slab and foundation soli design parameters for the subject project. We understand that post tension slabs are Intended for the homes of the proposed subdivision. Mi. Ron Martin of Post-TensIon Design Unlimited has requested from us, with your approval, to piOvld~ soil parameters for the design and construction plans of post- tension slab foundation systems as an alternative to the previously recommended conventional foundation system. At this time, we do not know the expansion index of the soils that will cap the building. pad areas. However, for structural design and cost estim?lte preparation, we provide the following soH parameters for different expansion indices. Category I is for soils with EI less than 50. Category II js for medium expansive soils with EI less than 90; Category III is for highly expansive soils with EI greater than 90 but less than 130, and Category. IV 1s for solis with expansIon indices higher than 130. Preferably, the latter Category IV soils should be excluded from the pad areas or provided with a 4-foot cap of lower expansion soils as a cover. However, if 7420 TRADE STREET a SAN DIEGO. CA 92121 Q (858) 549-7222" FAX: (858) 549-1604 .. E-MAIl..: geotsch@ixpres.com B9 1;>091:6];.'.9898 £9:91 9B00/9l/&9 (:\ --CJ:)....ul ¥1 11/17/2005 12:41 FAX 7609186~ RWR SAN DIEGO DIVISION 141003 Emerald PoInte Subdivision Carlsbad, California Job No, 97-7189 Page 2· Category IV soils are found In these areas after grading Is completed, we recommend that Category IV values be used. ThEL expansive solis should be moistened and compacted during grading with a moisture content at least 5 percent over optimum. After grading completion, the soils should be kept moist by irrigating them with sprinkJers at least 10 minutes every 2 days. Soli moisture content should be verified by our field representative before placing the sand and moisture barrier layers and within 48 hours prior to concrete placement. Bearing values are 2,000 pst for footings in fill and 3,000 psf for fpotlngs in formational soils. Please refer to our "Update Report of Preliminary Geotechnical Investigation" dated April 30, 2002, for other details in soil desJgn parameters. The post-tension foundation systems should.be designed by the structural engineer in accordance with post-tension slab design criteria of the Post-Tensioning Institute or other acceptable method. The post-tension desIgn based on the PTI method silould incorporate the geotechnical parameters presented on the followlng table entItled "Post-TensIon FoundatiQn System Design Criteria" for the particular f,)u.ldation category designated. POST-TENSION FOIJNDATION SYSTEM DESIGN CRITEIUA l'i~*:I::aite Index fI:I~~~;i~l!;~!~o "",,~.,< [L Clay-Type -Montmorillonite . _ l_?~lay Portion (Maximum) ----i--= k~:... D~th to Constant Soli Suction Yes 30% 5.0 ft L~i.:§gn ?lJctlon 1 6, j"'lo!stl.lre Veloclt >!..-.... ".-.-,.. 3.61t 0.7 in mo BEl Yes Yes 500/0 60% 7.0 ft 7.0 ft 3·fUt 3.6 ft 0.7 in ma 0.7 in/m~ t:>09t6fJ98E8 ~20 Yes 70% 7.0 It 3.6 ft 0.7 in/mo 11/17/2005 12:42 FAX 76091867~ Emerald Pointe Subdivision Carlsbad, California 11, Minimum Perimeter footIng Embedment Measured from Lowest Adjacent Grade RWR SAN DIEGO DIVISION ~004 Job No. 97-7189 Page 3, The post-tension slab and foundatIon system may have different steel reinforcing than the minimum reinforcement for conventJonal slabs indicated in our soU reports. However, the neW system should be reinforced at least In accordance with the standards of the industry. We recommend that perimeter and interior stiffener beams be used regardless of whh;:h method Is used for the post-tension slab foundation system. InterIor ribs or fOlJndations should have the bottom of excavation elevation at the same depth as the perimeter foundations. All other recommendations presented in our April 30, 20021 sorl report for this project remaln applicable unless superseded in writing by our finn. Geotechnical Exploration, Inc. should be consulted to provide addltional design parameters as required by the Structural Engineer. During and after completion of grading, building pad solis should have EI tests performed in typical soils encountered in the upper 4 feet of the building pad areas and at finish grade. These tests wlll help classify a weiflhted expansion index of the pad soils. The final foundatJon embl~dment shall be based on a weighted expansion Index for the building pad areas. p9 39\1d < J _. _'_'~~1='1_: 1::.-7_/.:::.2 ~O O:....:5-=-12::..::~4:..3 ...::F-=AX~7--=6~O::.91::..:8..:.6.:...:7 -:..:.::._----=R;;,;:Wc:::.;R-'S~A=N-'D~IF;GO D IVI S ION • 141005 , . Emerald Pointe Subdivision Carlsbad, Californfa Job No. 97-7189 Page 4 This opportunity to be of service is' sincerely appreciated. Should you have any questions regarding this matter, please contact the undersigned. Reference to our J.ob "!~ .. 97-7189 ~1lI help to expedite a response to yo.ur Inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION,. INC. ~= Jaime A. Cerros, P.E. R.C.E. 34422/G.E. 2007 Senior Geotechnical Engineer cc: Addressee 9(3 39'1d I39 PB9t6v989S