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Home My WebLink About; Terramar Unit 7; Soils Report; 1968-09-06- - - RECEIVED OCT 23 1% CITY OF CARLSBAD Engineering Departnznt September 6, 1968 Mr. Joe Hughes Post Office Box 1216 Carlsbad, California Job No. 7-172 SUBJECT: Soils Investigation for Terramar, Unit No. 7, Carlsbad, California. Dear Sir: SUMMARIZING THE ATTACHED F.H.A. PRELIMINARY SOILS INVESTIGATION, IT IS THE OPINION OF THE SOUTHERN CALIFORNIA TESTING LABORATORY, INC., BASED UPON FIELD INVESTIGATIONS AND LABOPATORY TESTS, THAT THE FOLLOWING STATEMENTS APPLY TO THE SUBJECT SUSDIVISION: 1. 2. - 3. 4. - .,,,~ .~ 5. A portion of the subdivision contains loose fill which will need to be recompacted to 90% to provide adequate bearing value to safely support either additional fill and/or structures. The natural, undisturbed soil has adequate bearing capacity to safely support the proposed loads. The loose fill after recompacting to 90% and the undisturbed natural ground possess low settlement and low expansive characteristics. Therefore, no detrimental movement will re- sult from these characteristics. The natural undisturbed soils and the loose fill when recom- pacted to 90% will have a safe bearing value exceeding 1840 pounds per square foot for one or two story dwellings. Cut slopes of 1 l/2 horizontal to 1 vertical and fill slopes of 2 horizontal to 1 vertical are stable for the material native to the site. ENGINEERING DEPT. LIBRARY City of Carlsbad 2075 Las palmas Drive Carlsbad, CA 92009-4859 .,-~e “,S 3 ,~ ,,,-, ,~, ;. .A ~..~, ,. .., ~I .~, .~ - .~,. ,. ..,j .’ - - .- - - -.~ - Soils Investigation for Terramar, Unit No. 7, Carlsbad, California. Job NO. 7-172 September 6, 1968. Page (2) 6. It is the recommendation of the Southern California Testing Laboratory, ,Inc., that the questionable fills be excavated to firm natural ground and the soil so removed be stockpiled off of the site for future use. Prior to replacing the fill, the base of the excavation shall be prepared in accordance with the attached grading specifications. The fills taken from the cuts made on the site shall then be placed in accord- ance with the attached Grading Specifications. All oversized material (larger than six (6) inches in diameter) shall not be placed in the compacted fills. The limits of the above recommended excavation and recompac- tion shall extend to the side yard property line and behind the required building setback line, to a line located not more than ten (10)feet in front of the rear property line. 7. The Southern California Testing Laboratory, Inc. realises that there are additional fill areas on the site. Upon completion of the clearing of the site, fill areas will be tested to ascertain whether they comply with Federal Housing Administra- tion Specifications 79G. Lots with questionable fill shall be treated as specified in Paragraph No. 6 listed above. 8. Any additional imported fill should be compacted to 90% and checked to insure that it is non-expansive, possesses low settlement characteristics, and has sufficient strength to provide the bearing value and stability stated in Paragraphs 4 and 5 above. If you have any questions after reviewing our report, @lease do not hesitate to contact this office. This opportunity to be of service is sincerely appreciated. - - Respectfully submitted, SOUTHERN CKCFORNIA TESTING LAB., INC. - - . .- CHW/am C. H. Wood, R.C.E~. 10778 cc: (4) submitted (4) Ranch0 Santa Fe Engineering -. - _- - - September 6, 1968 Mr. Joe Hughes Post Office Box 1216 Carlsbad, California Job No. 7-172 SUBJECT: Soils Investigation for Terramar Unit No. 7, Carlsbad, California. Dear Sir: In accordance with your request, we have performed a soils investigation of the conditions at the above subject site. We are transmitting here- with a report of this investigation. The analysis of our findings is intended to provide the required in- formation to determine the suitability of the site for residential development. - In general, we found the site will be suitable provided that existing loose fill be removed, replaced and compacted to 90%. - .- .- .- - -. If you have any questions after reviewing our report, please do not hesitate to contact this office. This opportunity to be of service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA TESTING IAB.. INC. CBW/am C. H. Wood, R.C.E. .10778 cc: (4) submitted (4) Ranch0 Santa Fe Engr. - INSPECTION * TESTING * RESEARCH * D;“ELO&ENT - 6280 Riverdale St. l San Diego, California 92120 l Phone 283 -6134 L\LL ILeo”TS A”r *“aUIT*Io AI I”(L cc.UmDw4IIA\L P”OPL”T’I 0, CLlmdI.. .m*011zATIO* TO” ,“mL,C.,,OY 0, 0”” “ICOIT,. CO*CLY*,OU,. 0” *xT”.CI, rIou 011 RTGA”DI”C 1la” IS “ls=“YID PrzYDIMT 0”” v”lnl* ..l”D”AL AS I ““l”.L ,Io,IcIIo* TO CLIL*,*. ,“L ,“.L,C AND O”“SE:L”I,, -. - - -. -. -. - - -. .- - _- - -. REPORT OF SOILS INVESTIGATION TERRAMAR,~ UNIT NO. 7 CARLSBAD, CALIFORNIA SCOPE: This report presents the results of our soils investigation for the subject development which is a subdivision of a portion of Lot H, Rho Aqua Hedionda, City of Carlsbad, County of San Diego, State of California. It is our understanding that 16 lots are planned for the site. It is further understood that conventional one or two story residences are planned for the site. A Plot Plan is presented on the attached Figure No. 1. The soils investigation was undertaken to: 1. Determine the phys ical characteristics of the prevailing subsoils. 2. Determine the supporting capacities,and consolidation or settle- ment characteristics of the in-situ soils. 3. Provide design information regarding the site preparation and foundations. 4. Determine potential construction difficulties and provide re- commendations concerning these difficulties. SUMMARY: For your convenience, a summary of our findings and conclusions are presented as follows: - - - - - - - Soils Investigation for Terramar, Unit No. ?, Carlsbad, California. Job No. 7-172 September 6, 1968. Page (2) 1. The subject site is located on the east-facing slope of an elongate hill which trends northwest to southeast. Elevations range from 38 feet to 44 feet above ~Mean Sea Level. A considerable quantity of loose end-dumped fill exists as a cap' over the northeast and southeast margins of the site, and varies in depth from about ten feet on the edge of the lake to about four feet forty or fifty feet west of the top of the lake bank. Additional older fill exists to a depth of at least seven feet beneath Lot No's. 212, 123, 214, 215 and 216. All fill materials encountered are uncompacted and exhibit high consolidation characteristics when allowed to contact water. 2. Due to the conditions described above, it is recommended that all loose fill be removed, replaced and compacted for its full depth. The alternative to this recommendation is to support all portions of the structures (including floors, slabs, and patios) on foundations which are extended into the firm, undisturbed natural soils. 3. The expansive characteristics of the soils found on-site will not require special consideration and/or design so that structural damage is not likely to occur. 4. The allowable bearing pressures for the indicated soil conditions may be expressed by the following formulas for continuous and square footings: Soil Condition I: Undisturbed Natural Soils. Continuous Footings: q = 1.44 + 0.46 x D + 0.24 x B Square Footings: q = 1.93 + 0.46 x D + 0.19 x B Soil Condition II: Native Soils Recompacted to 90%. Continuous Footings: q = 1.15 Square Footings: q = 1.49 Where q = Allowable soil bearing foot for full live and D = Minimum footing depths + 0.50 x D + 0.19 x B + 0.50 x D + 0.15 x B pressure in Kips per square dead loads. below adjacent grade.in feet. B = Footing width for continuous or square footings in feet. - .- - - - - - ~-~ - - - - Soils Investigation for Terramar, Unit NO. ?, Carlsbad, California. Job No.7-172 September 6, 1968. Page (3) 5. 6. 7. 8. 9. 10. The above allowable loads may be increased by l/3 for wind and/or seismic loading and should be decreased by l/4 for dead load only. It is recommended that the allowable bearing pressures as deter- mined by the above formulas be limited to 3,000 pounds per square foot for both soil condition I and II. It is recommended that conventional spread footings designed in accordance with the above recommended bearing pressures be founded a minimum of 1.0 foot below adjacent grade and have a minimum width of 1.0 foot. It is further recommended that adjacent footings founded at different bearing levels be so located that the slope from bearing level to bearing level be flatter than 1.0 horizontal to 1.0 vertical. . . It has been determined that the undisturbed natural soils will support the proposed fills. The proposed fill slopes will be stable with relation to deep seated failure if constructed at or flatter than 2 horizontal to 1 vertical. Cut Slopes, if required, will be stable if excavated at or flatter than 1 l/2 horizontal to 1 vertical. Estimated maximum settlement ~provided that the loose uncontrolled fill is recompacted will be less than 3/8 inch. Z4lowable passive pressures of the soils in either their native or recompacted state may be assumed to be 240 pounds per square foot at the surface and increasing at a rate of 130 pounds per square foot per foot of depth. These passive pressures may be increased l/3 for wind and/or seismic loading. Active soil pressures for the design of basement walls or retaining structures for a level backfill condition and no surcharge pressures may be assumed to be equivalent to the pressure of a fluid weighing 37 pounds per cubic foot. For retaining wall backfill, sloping at a slope ratio of 2:l the active pressure may be assumed to be equivalent to the pressure of a fluid weighing 46 pounds per cubic foot. Earthwork and grading contemplated for the site preparation should be accomplished in accordance with the attached Recommended Grading Specifications. Structural backfill should be compacted to 90%. - - - - - - - - - - - - - - - Soils Investigation for Terramar, Unit No. 7, Carlsbad, California. Job No. 7-172 September 6, 1968. L Page (41 FIELD EXPLORATIONS: Three borings were drilled at the locations indicated on the attached Figure No. 1, by means of a rotary-bucket type drill rig on August 8, 1968. The borings were conducted by an independent contractor working under the direct supervision of our personnel. Logs of the borings were recorded at the time of drilling and are pre- sented on Figure No's. 2 and 3. The soils are described in accordance with the Unified Soils Classification system as illustrated on the.attached chart. Soil densities for granular soils are given as very loose, loose, medium dense, dense, or very dense. ,Consistency of cohesive soils are given as very soft, soft, medium stiff, stiff, very stiff and hard. Representative core samples were obtained by means of a 2 l/2" I.D. x 3 l/4" O.D. split tube sampler driven into the soil by means of the "kelly bar" of the drill rig. The energy required to drive the split tube sampler 12 inches into the soil is indicated on the boring logs as the "penetra- tion resistance". The core samples were carefully removed, sealed and re- turned to the laboratory for testing. LABORATORY TESTS: Laboratory tests were performed in accordance with generally accepted American Society for Testing and Materials test methods. Tests were per- formed on representative samples in order to determine their shear strength, natural density and moisture content. The results of these tests are pre- sented on the attached copy of boring logs. In addition, the gradations, atterburq limits, maximum densities, angles of internal friction and - ,- - - - - - - - - - - Soils Investigation for Terrama Job No. 7-172 ,r, Unit No. Page (5) 7, Carlsbad, California. September 6, 1968. cohesion were determined for typical samples. The results of these tests are presented in tabular form on attached Figure No. 4. Consolidation tests were performed on 5 samples. The results of these tests are presented on attached Figure NO'S. 5 and 6. GEOLOGY: The entire site is underlain by medium dense light reddish brown silty fine sand of a Quaternary marine terrace deposit, which is probably equivalent to the Pleistocene Linda Vista Formation. - - - - - - - - - - - - - - - - - - 45 f4 ;I:.! fgt, ,: .:‘“. f-..; :...... _...? 4.. --.: ,. +: l TEST BORING LOCATION f$# UNCONTROLLEC) NLL 6280 RIVERDALE STREET SAN DIEGO. CALIFORNIA 92120 714283.6134 TERRAMAR UNIT NO. 7 Portion of Lot "H" Agua Hedionda City of Carlsbad, California SCALE 1"=200' PLOT PLAN BY G.M. DATE 8-13-68 'OS No' 7-172 ~~ FIGURE NO. 1 - - - - - - - - - - - - - - - - - - - BORING NO. 1 0 E Y M S Relative Density of 76.7%. 2 (SW 13.0 98.5 3.5 0.99 8 :: 4 4 3 Moist SLIGHTLY SILTY F SAND. Un- controlled fill. Relative Density (SM/SW) 3.0 87.4 2.8 1.06 Er: 2 6 ; 8 E z 10 E 6.5 108.7 8.5 1.88 SILTY F SAND 3 2 I2 Terrace Deposit. E 5 I4 Medium dense. # 13.0 109.1 9.1 2.64 !i a LEGEND = Sample Location. E = Sampler penetration resistance in feet-kips per foot. Y = Dry density in pounds per cubic foot. M = In-situ moisture content in percent of dry weight. S = Shear strength in kips per square foot. TERRAMAR, UNIT NO. 7 6280 RIVERDALE STREET SAN OIEGO. CALIFORNIA 92120 714-283~613-4 BORING LOG - - - - - - - - - - - - - - .- - -. BORING NO. 2 E 0 Y M S Dense SILTY F SAND Natura 2 (SM) Mediums Dense SILTY F SAND (SM) 13.0 104.8 4.1 2.10 4 6 Terrace Deposit ---- 8 7.1 107.6 5.6 1.09 8 2 10 --- % cl 3 I2 2 i BORING NO. 3 w" 0 E z 2 17.5 111.4 4.0 0.70 6 2 4 2 6 7.3 1.07 8 !i 8 E 10 SILTY F. SAND Terrace Deposit (SM) E 14.4 1.76 12 See Figure No. 2 For Legend 6280 RIVERDALE STREET TERRAM?+R,LJbTIT NO. 7 SAN DIEGO. CALIFORNIA 92120 714-283.6134 .,~ - - -. - - - - - .- - - - - - - - .- GRAIN SIZE DISTRIBUTION ATTERBERG U. S. Standard Sieves Hydrometer LIMITS 05 .005 .OOl SAMPLE #4 #8 #16 #30 #SO #100 #200 'mm mm mm LL PL PI Bl@ 2.0' 100 99 97 89 56 32 22 19 11 7 16 NP - B2@ 3.5' - 100 99 93 61 45 27 23 13 8 18 NP - MAXIMUM DENSITY AND OPTIMUM MOISTURE CONTENT Per A.S.T.M. 1557-66T, Method A Sample Description Bl @ 1.5-2.5' Lt. Reddish Brown Silty F. Sand Bl @ 5.0-6.0' Yellowish Brown Slightly Silty F. Sand Maximum Optimum Density Moisture (PCf) Content 128.5 8.9% 115.3 10.3% DIRECT SHEAR TESTS (All Samples Saturated and Drained) Cohesion Internal Sample Description (Psf) Friction B3 @ 2.8' Undisturbed Topsoil 250 32.2O Bl @ 1.5'-2.5' Remolded to 90% 180 39.6O Bl @ 5.0'-6.0' Remolded to 90% 200 37.0° TERRAMAR, UNIT NO. 7 6280 RIVERDALE STREET .~~ .- .,. -__- - - - - - .- -r -. - 6 ’ (KIPS/SQ. FT.) io SOUTHERN CALIFORNIA TESTING Consolidation vs. Pressure LABORATORY, INC. _ TERRAMAR, UNIT NO. '7 6280 RIVERDALE STREET SAN DIEGO. CALIFORNIA 92120 714-283-6134 :-I”2 -.. _ .,.-. Fig. No. 5 -- ~~~~~~~ 0 -2 3 4 2 az 2 5 3 w 0 c / 2 0 cl RE/YouLoEo 70. % 3 s s2 3 02 LOAD i io (KIPVSQ. FT.) _ SOUTHERN CALIFORNIA TESTING Consolidation vs. Pressure. LABORATORY, INC. Project -MAR, 6280 RIVERDALE STREET UNIT NO. 7 SAN DIEGO. CALIFORNIA 92120 714.283.6134 Job No. l-172 Fig. No. 5 -. -. - - - - - - - - - - - - - RECOMMENDED GRADING SPECIFICATIONS . GENERAL PROVISIONS GENERAL INTENT: The intent of these specifications is to establish procedures for . . clearing, compacting natural ground, preparing areas to be filled and placing and compacting fill soil to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary soils investigation report and)or the attached special provisions, are a part of the recommended grading specifications and shall supercede the pro- visions contained hereinafter in the case of conflict. INSPECTION AND TESTING: A qualified soil engineer shall be employed to supervise, inspect and test the earthwork in accordance with these specifications. It will be the soil engineer's responsibility to provide adequate supervision, so that he may certify that the work was accomplished as specified. If, in the opinion of the soil engineer, substandard conditions are en- countered, such as questionable soil, poor moisture control, inadequate compaction, adverse weather, etc., he will be empowered to stop construction until the conditions are remedied or corrected. Soil tests used to determine the degree of compaction will be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density and Optimum Moisture Content. A.S.T.M.D1556-64T Density of Soil In-Place. A.S.T.M. D1557-64 - RECOMMENDED GRADING SPECIFICATIONS. GENERAL PROVISIONS. .- - - - - - - Page (2) PREPARATION OF AREAS TO RECEIVE FILL: All vegetation, brush and debris shall be removed, piled and burned or otherwise disposed of. After clearing, the natural ground shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the minimum density specified in the special provisions or the recommendations contained in the preliminary soils in- vestigation report. When the slope of the natural ground receiving fill exceeds 20% (5 Horizon- tal to 1 Vertical), the original ground shall be stepped or benched. Benche: shall be cut to a firm consistent soil condition. The lower bench shall be at least 10 feet wide and all other benches at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified hereinbefore of or compacting natural ground. Ground slopes flatter than 20% shall be benched when considered necessary by the soil engineer. - FILL MATERIAL: Materials placed in the fill shall be approved by the soil engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids.~ The definition and disposition of oversized rocks, expansive and/or detrimental soils are covered in the special provisions. Expansive soils, soils of poor gradation or strength characteristics may be thoroughly mixed width other soils to provide satisfactory fill material, but only with the explicite consent of the soil engineer. - . - -. - - - - - - - - - - - - - RECOMMENDED GRADING SPr.<IFICATIONS. GENLaAL PROVISIONS Page (3) PLACING AND COMPACTION OF FILL: Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compactive effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the minimum specified density with adequately sized equipment, either specifically designed for'soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the special provisions or the recommendations contained in the preliminary soils investigation report. Field density tests to check the degree of compaction of the fill will be taken by the soil engineer or his representative. The location and frequency of the tests shall be at the soil engineer's discretion. In general, the density tests will be made at an interval not exceeding 2 feet in vertical rise and/or 500 cubic yards of fill placed. SEASON LIMITS: Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill has been achieved. Damage resulting from weather shall be repaired before accept- ance of the work. UNFORESEEN CONDITIONS: In the event that conditions are encountered during the site preparation and construction that were not encountered during the preliminary soils RECOMMENDED GRADING SPECIFICATIONS. Page (4) GENERAL PROVISIONS - investigation, Southern California Testing Laboratory, Inc. shall be notified immediately. Southern California Testing Laboratory, Inc. - assumes no responsibility for conditions encountered which differ from the conditions encountered and described in the preliminary soils in- - vestigation report. - - - - - - - - - - - - - - - - RECOMMENDED GRADING SPECIFICATIONS SPECIAL PROVISIONS The minimum degree of compaction to be obtained in compacting natural ground and in the compacted fill shall be 90%. Detrimentally expansive soil is defined as soil which will swell more than 3% against a pressure of 150 pounds per square foot from a condi- tion of 90% density and optimum moisture content to saturation. In addition, those soils which have a liquid limit exceeding 30 or a plasticity index exceeding 15 will be expansive. Oversized fill material is defined as rocks or lumps over 6 inches in diameter. At least 40% of the fill soil shall pass through a No. 4 U.S. Standard Sieve. Imported Fill shall be select, non-expansive fill. In addition it shall have a minimum angle of internal friction of 32' and cohesion of 225 pounds per square foot when tested in direct shear and compacted to 90% and in a saturated and drained condition. - - - - - - - .- -- - - - - - - - , * UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION GROUP SYMBOL 1. COARSE GRAINED, More than half of material is larqer 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 WITH FINES (Appreciable amount of fines) 11. FINE GRAINED, More than half of material is smaller than No.,200 sieve size. SILTS AND CLAYS Liquid Limit less than 50 SILTS AND CLAYS Gw GP GM GC SW SP sn SC ML CL OL MH Liquid Limit greater than 50 CH OH HIGHLY ORGANIC SOILS PT TYPICAL NAMES Well graded gravels, gravel- sand mixtures, little or no fines. Poorly graded gravels, gravel sand mixtures, little or no fines. Silty gravels, poorly graded aravel-sand-silt mixtures. Clayey gravels, poorly graded gravel-sand, clay mixtures. Well graded sand,gravelly sands, little or no fines. Poorly graded sands,qravelly sands, little or no fines. Silty sends, poorly graded sand and silt Clayey sands, sand and clay mixtures. pooxly graded mixtures. Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plast- icity Inorganic clays of low to medium plasticity,gravelly clays, sandy clays,silty clays, lean clays. Organic silts and organic silty clays of law plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorganic clays of high plasticity, fat clays. Organic clays of medium to high plasticity. Peat and other highly organic soils. SOUTHERN CALIFORNIA TESTING LABORATORY