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Home My WebLink AboutCT 01-16; CASA LAGUNA; UPDATE SOILS INVESTIGATION; 2002-08-07NORTH coariTY COMPACnON ENGINEERING. INC. August 7.2002 Project No. CE-6687 The Merit Group, Inc. 2171 EI Camino Real Suite 202 Oceanside, CA 92054 Subject: Update Soils Investigation/Inspection Proposed Condominium Development 670 Laguna Drive Carlsbad, Califomia Reference: "Geotechmcal Report" prepared by Agra Earth & Environmental dated August 24,2000 Dear Mr. Buckmaster: the purpose of updating the above referenced geotechmcal report. •1 Per your request, we have inspected the subject site and performed a subsurface investigation for - N I FIELD INVESTIGATION The field investigation was performed on July 31,2002 and included an inspection of the site and the excavation of two exploratory trenches, with a backhoe to depths of 9 feet Location of test pits are shown on the attached Plate No. One, entitled "Test Pit Location Plan". As excavation proceeded, representative bulk samples were collected. In place natural densities and moisture contents were determined at different depths in the excavations and are included on Plate No.'s Two and Three. Subsequent to obtaining soil samples, om: exploratory excavations were backfilled. SOIL CONDmONS Loose surficial soils (silty-sands) consisting of old fill/plowed ground were found to be 4 feet . and VA feet in depth in Test Pit No.'s One and Two, respectively. Underlying native soils were stiff silty and sandy clays (colluvium) succeeded by medium dense silty-sandstones and clayey- sandstones. . .^-j\'": '^^ . ^ . :-\:^ --V^^-JV--''..H ivjj^i^'s 0.50X302002^ ESCONDIDO, CA 92030 (760) 430-1116 FAX (760) 741-6563 MORTHCOaiiTY COMPACTION ENGINEERING, INC. Project No. CE-6687 Page 2 The upper mantle of fill soils were found to have an expansion index of 11 and are classified as being "very low" in expansion potential. The underlying silty and sandy clays (colluvium) were foimd to have an expansion index of 115 and are classified as being "very high" in expansion potential. Groimdwater was not encountered at the time of our investigation. However, groundwater seepage was encountered in the geotechnical report by Agra at 15 feet to 18'A feet below the existing ground surface. In our opinion, groundwater encountered at this depth will not cause significant problems during and after grading. Due to the depth of groundwater, soil cohesion characteristics and a relatively high density of colluvium soils and formational soils underlying the site, it is our opinion that soil liquefaction occurring at the site will be unlikely. LABORATORY SOIL TESTING All laboratory test were performed on typical soils in accordance with accepted test methods of the American Society for Testing and Nfaterials (ASTM). Tests conducted include: ' •^ H A) . Optimum Moisture & Maximum Density (ASTM D-1557) B) . Direct Shear (Remold) (ASTM D-3080) C) . Sieve Analysis (ASTM D-421) D) . Field Density & Moistiire (ASTM D-1556) E) . Expansion Potential (FHA Standard) Test results are tabulated on the attached Plate No.'s Two through Four entitied "Exploration Log" and "Tabulation of Test Results". CONCLUSIONS Briefly, our updated investigation revealed that soil conditions at the site remain as presented in the geotechmcal report by Agra. Therefore, we are updating their report It is our understanding, that the post tetision slab and foundation alternative presented in the r^ Agra will be incorporated into the subject dweUing um'ts. Therefore, if a post tension foundation system is utilized, lime treatment of soil during grading will not be required. All other reconunendations presented in the report should be considered valid and be incorporated into the j planning design, grading, and construction phase ofthe subjectproject MORTH COCIMTY COMPACTION ENGINEERING. INC. Project No. CE-6687 Page 3 We should be contacted to review the project foundation plans and grading plans upon their completion to assure recommendations presented in the report by Agra Engineering were properly incorporated into them. In addition, the soils engineer declaration and general notes on the project grading plan should reference the report by Agra Engineering as well as this updated report If you have any questions, please do not hesitate to contact us. This opportunity to be of service is sincerely appreciated. Respectfully submitted. North County COMPACTION ENGINEERING, INC. f Ronald K. Adams ;Presfdent ,, ' -it* DaieR-Regli^ Registered Civi' Geotechnical Engini "14 RKA:paj cc: (4) submitted 1 i NORTH COCINTY COMPACTION ENGINEERING. INC. EXPLORATION LEGEND UNIFIED SOIL CLASSMCATION CHART .son. DESCRIPTION GROUP SYMBOL TYPICAL NAMES I. COARSE GRAINED; More than half of material is larger than No. 200 sieve size. GRAVELS CLEAN GRAVELS More than half of coarse fraction is larger than No. 4 sieve size, but smaller than 3". GRAVELS WITH FINES (Appreciable amount of fines) SANDS CLEAN SANDS More than half of coarse fraction is smaller than No. 4 sieve size. SANDS WTTH FINES ! (appreciable amount of fines) .1: n. FINE GRAINED: Morethan half of material is jailer than No.200 sieve size. SILTS AND CLAYS Liquid Limit less than SO SILTS AND CLAYS Liquid Limit greater than SO HIGHLY ORGANIC SOILS GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Well graded gravels, gravel-sand mixtures, littie or no fines. Pooriy graded gravels, gravel sand mixtures, littie or no fines. Silty gravels, pooriy graded gravel- sand-silt mixtures. Clayey gravels, poorly graded gravd-sand, clay mixtures. WeU graded sarid, gravely sands, littie or no fines. Pooriy graded sands, gravely sands, Uttie or no fines. Silty sands, pooriy graded sand and sih mixtures. , ; Clayey sands, poorfy graded sand ;.andcl^imxtures. .' Inorganic silts and very fine sands, rock flour, sandy sih or clayey- sih-sand mixtures with sUght plasticity. Inorganic days of low to medium plastidty, gravdy days. lean days. Organic silts and oiganic sihy days of low plastidty. Inorganic silts, micaceous or diatomaceous find saaiy or silty soils, dastic sihs. Inorganic days of high plasticity, fiit clays. Organic days of medium to high plastidty. Peat and other highly organic soils. us - Undisturbed, driven ring sanq)Ie or tube sample CK - Undisturbed chunk sample BG-Bulksample ^ ' . V - Water level at time of excavation or as indicated APPENDIX *A' A NORTH COUNTY COMPACHON ENGINEERING. INC. SOIL TESTING & INSPECnON SERVICES TEST PIT LOCATION PLAN I PROPOSED CONDOMINIUM DEVELOPMENT LAGUNA STREET CARLSBAD, CALIFORNIA B-5 TD=2r NCCEI TEST PIT #2 TD»21.5'i I . B-3 TD=2r 4^ Tippraxlniate location of Existing Residence NCCEI TEST PIT it .[ TD=21' TD=21' LAGUNA DRIVE =^ .•-. 1/ * PROJECT NO. PLATE NO. ONE NORTH COUNTY COMPACTION ENGINEERING. INC. EXPLORATION LOG 1 PROJECT NAME: LAGUNA STREET. CARLSBAD DATE LOGGED: 07/31/02 ELEVATION: EXISTING GRADE TEST PIT NO. ONE Depth (Feet) Sample Type Dry Density (pcf) Mdsture Content (%) Passing #200 Sieve Sample Depth Soil Classi- fication Description & Remarks SM Red Brown, Humid, Loose Silty-Sand 1-(Old Fill) (Remove and Recontpact) 2-BG 24.9 2' ^ow Expansion) 3- 4-4- CL Grey Brown, Moist, Stiff Sand-Clay 5-• • • (Furm Natwe - CoHuvium) 6- 7- (Ifigh E}q}anaon) 6- 7- SC Grey Yellow, Moist, Medium Dense Clayey-Sandstone (Fonnation) 8-8- Bottom of Test Pit * ''^ >' "f.'l* 111 "-..'.j-j-J PROJECT NO. CE-6687 PLATE NO. TWO NORTH COCINTY COMPACTION ENGINEERING. INC. EXPLORATION LOG PROJECT NAME: LAGUNA STREET, CARLSBAD DATE LOGGED: 07/31/02 ELEVATION: EXISTING GRADE TESTPITNO._rWQ_ •-•p-^^-^s, Depth (Feet) 2- t .^4-5—' 7- 8- Sample Type Dry Density (pcf) BG : 105.4 Moisture Content (%) 19.6 Passing #200 Sieve 70.1 Sample Depth 3' 5' Soil Classi- fication SM CL SC Description & Remarks Grey Brown, Dry, Loose Silty-Sand (Old Fill) (Remove and Recon^act) ^w Expansion) Grey Brown, Wet, Stiff Sandy-Clay (Fum Native - Colluvium) (High Expansion) Grey Yellow, Moist, Medium Dense Clayey-Sandstone (Formation) Bottom of Test Pit - i PROJECT NO. rE-6687 PLATE NO.__JIHBEE NORTH COCINTY COMPACTION ENGINEERING. INC. TABULATION OF TEST RESULTS OPTIMUM MOTSTITRH/MAXIMTJM DENSITY son. DESCRIPTION Red Brown Silty-Sand Grey Brown Sand-Clay TYPE MAX. DRY DENSITY gg. CU, FT) Pl@2' 126.3 P2@3' 118.0 EXPANSION POTENTIAL SAMPLE NO. Pl (q). 2' P2(a).y CONDITION . Remold 90% Remold 90% INTTIAE MOISTURE (%) 9.5 13.5 AIRDRY MOISTURE (%) 3.1 9.1 FINAL MOISTURE (%) . . 16.6 32.2 DRY DENSITY (PCF) 113.7 106.2 LOAD (PSF) 150 150 SWELL (%) 1.1 15.0 EXPANSION INDEX 11 115 OPT. MOISTURE (%DRYWT) 10.1 14.0 •:' il SAMPLE NO- DIRECT SHEAR P1<g).2' CONDITION Remold 90% ANGLE INTERNAL FRICTION 31 COHESION INTERCEPT (PCF) 100 PROJECT NO. CE-6687 PLATE NO. FOUR