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Home My WebLink AboutCT 76-06; ROYAL HOMES; SOILS REPORT; 1980-01-14DUCO· e Engineering, Inc. FOUNDATION 8: GEOLOGIC INVESTIGATIONS FILL CONTROL -SOIL TESTING 1170 CENTRE DRIVE, SUITE F . WALNUT, CALIFORNIA 91789 (213) 964-3440 . 964-3449 REP 0 R T o F SOl L S I N V EST I GAT ION T R ACT NUMBER 76-6 W EST SID E o F CHI N QUA PIN A T S Y M E D R I V E CARLSBAD, CAL I FOR N I A AVENUE FOR: Carlsbad Development Corp. P.O. Box B . Carlsbad, Ca. 92008 Job No.: 9-2.77 January 14, 1980 Page One ~ January 14, 1980' Job No.: 9-277 Introduction This report presents the results of a soils investigation for a proposed 15 lot residential subdivision, Tract No. 76-6 to be developed on the west side of Chinquapin Ave. at Syrne Dr., in the City of Carlsbad, County of San Diego, ,California. Figure No. 1 presents a plot plan of the site showing the surface features and soils data pertinent to this report. The geologic conditions pertaining to the development of this site as proposed are'contained in the Geologic Study dated 1-2-80, prepared by Bob Di~key, submitted as a part of this report. The object of this investigation was to gather information and data regarding the surface and subsurface soils conditions upon which to base our recommendations for site preparation, grading and construction of the proposed residential structures. The results of our field and laboratory investigations which form the basis for our recommendations are included 'as a part of this report. Site Conditions The subject site occupies a rectangular shaped parcel of property bounded oy Chinquapin Ave. on the west and by houses and rural property on the remaining three sides. At the time of our field investigation the site contained a residential structure, on proposed Lot No.5, with associated trees, shrubs, lawns and a shed along the north property line. The remaining portion of the site is presently a producing tomato and squash field. The natural soils encountered consisted of firm to dense silty fine to medium sands. Current drainage of the site 1S qy sheetflow from the east to the west. No ground water or caving of the test hole side walls were encountered in any of the test holes to the depths excavated. Field Investigation The subsurface soils conditions were explored by excavating five (5) engineering test holes to depths of 6 to 10 feet using a backhoe with an 18 inch wide bucket. The app.roximate locations of the test holes are shown along with the surface features and pertinent soils data on Figure No.1. Both relatively undisturbed and disturbed bulk samples of the typical soils encountered in the test holes were recovered to be subjected to laboratory testing and analysis. A continuous log of each test hole was kept in the field at the time of excavation. These test hole logs, reflecting the condition and classification of each soil strata encountered, based on the Unified System of Soil Classification, are attached to this report as Figures 2 through 6. Page Two January 14, 1980 Job No.: 9-277 Laboratory Investigation In-situ moisture and density tests were performed on the undistur'bed samples an~ the results of' these tests are shown on tl)e appropriate test hole' log at the depth sampled~ Also shown are ,the results of tests made to determine the relative compaction of the samples compared to the maximum density determined ~ith ASTM test method D1557-70. The expansion potential of the typical onsite soils were determined in accordance with the U.B.C. test standard 29-2. The result of the laboratory tests performed on the bulk samples of the typical soils are summarized as follows: Soil Type A Silty fine to B -Silty fine to C -Clayey sand Hole No. I 2 4 med. med. Max. sand 127.0 sand 127.5 131.4 Depth, Ft. 8.0 2.0 2.5 Conclusions and Recommendations Den. P.C.F. " " Opt. Moist. Expan~ Index 9:7 % 3 8.5 % 4 8.2 O. Shear Angle Cohesion, P.S.F. 320 75 340 150 380 50 Development of the site, as proposed, is considered feasible from a soils engineer- ing standpoint based on the implementation and incorporation of the recommendations which follow ipto the site preparation, grading and construction of the proposed residential structures. Site Preparation and Grading Prior to the start of grading; the existing trees not to remain shall be removed and hauled offsite. The organic debris resulting from the tree removal and all surface vegetation shall be stripped and hauled offsite to the satisfaction of the soils engineer. Any remaining roots encountered during the grading operation shall be picked and removed from the site. The existing structures not to remain shall be demolished and hauled offsite. A search shall be made to locate any underground private sewage disposal systems. Any such systems encountered shall have the septic tanks removed and the cesspool pumped as necessary and filled to within 5 feet of finished grade with clean sand and, gravel jetted in place with water. The top 5 feet of the cesspool shall be removed and ,the excavation brought to grade with compacted f~ll along with any other excavation resulting from demolition or removal of a subsurface structure. Prior to the placing of any fill soils, the surface of the natural ground to receive fill shall be rerp.oved or windrowed t() a depth of 12 inches, watered as necessary to obtain opti~um moisture content and precompacted to the minimum requirements. A,similar grading procedure shall be implemented upon the finished grade surface where proposed cuts to, create building, pads are less than 12 inches in depth. Page Three January 14, 1980 Job No. 9-277 Site Preparation and Grading (con't.) F'ill soils shall be spread in 6 inch loose lifts, watered as necessary and compacted to in excess of 90% of the maximum density as determined by ASTM test method D1557-70. The anticipated subsidence in the surface soils due to processing of the natu~al ground to receive fill, tree removal and processing of the surface of the shallow. cut pads· is expected to be on the order of 2.0 inches. The anticipated shrinkage in soil volume from cut to fill is expected to be on the order of 10 to 15%. Expansive Soils The results of the laboratory test performed on the typical soils types encountered on the site indicate the soils are nonexpansive to very lowly expansive in nature. Based on the results of these tests it is our opinion that no remedial construction measures will be necessary providing that the proposed imported soils are also of a nonexpansive nature. All import soils should be approved prior to reaching the site. Foundations Based on provisions of the foregoing recommendations, the proposed residential structures may be supported on conventional continuous and square footings designed to obtain the required soil bearing at a minimum depth of 12 inches below the lowest adjacent finished ground surface. The recommended soil bearing value for footings imbedded as recommended into compacted fill or firm natural ground shall be 1500 P.S.F. The foregoing values are for dead and live loads and may be increased 1/3 for temporary horizontal forces. Cut and Fill Slopes o The recommended maximum graded angle for cu~ and fill slopes ,shall, he 1~:1 (@34 )., Slopes constructed' at this angle are deemed grossly stable to the designed heights. The recommendations contained in this report are based on the results of our field and laboratory investigations combined with the principles of modern soil mechanics and sound engineering judgement. Should any unusual conditions arise during the design or construction of this project, this firm shall be notified in order that proper modifications to the recommendations contained herein may be made as d~emed necessary . . Should you have any questions with regard to this report or the recommendations ,contained herein, please contact this office. Respectfully submitted, DUCO ENGINEERING, INC. Approved by: .~ak Ronald Cobine 10863 RC:mw . e e -.@ ~J I , i 0 CD ~s- -~ tt: NO GRAJ)/NG ~2 I:::\ ;7 lli S- '" A U) I I ~ a ~ I @ (j) , . ~3 .. ~4 CHINQUAPIN AVE. , DUCO ENGINEERING ~ (9 LOCATION OF SCALE I": 60 ' : ,. J TEST HOLE JOB NO. 9-277 , 1170 CENTRE DR., SUITE F, WALN UT, CALIF. FIGURE No.1 DATE DRILLED 12-28-79 Depth In Feet o - · - 5 - - - -I- I .o- lD - - - - 15 - - - · · 20 - - - - - 25 A 108.0 8.8 DUCO .Engineering, Inc. LOG OF BORING NO. 1 PROJECT NO. 9 .... 277 FlELD CLASSIFICATION Silty fine to medium sand ~ brown -firm -damp Material becomes reddish brown in color and moist 85.0 FIGURE NO. DATE DRILLED 12-28-79 Depth In Feet o - ~ 1 -- - 5 - - - .-- -' 10 - - - - 15 - - - - 20 - - - - - 25 B 115.7 8.6 --- DUCO Engineering, Inc. e LOG OF BORING NO. 2 PROJECT NO. 9"-277 FJELD CLASS1FICATlON Silty fine to medium sand -brown -firm -damp 90.7 Material becomes reddish brown in color and moist FIGURE NO. DUCO Engineering, Inc. e DATE -DRILLED 12-28-79 LOG OF BORING NO. 3 PROJECT NO. 9-277 ° A ~o... ~ ~ ~ ~ 0 th Dep In Feet ~~ q,'" ;:;.Cj ..,v ~o ~.,.... ~o~"" ~«¢(/ ° N A 'Y4I ~ ~v .$' '" A v"'>o ....,,'Y 'Y<' ~ ~~ O~ ~ -o'S. ..,-$' ~o O~ FJELD CLASSIFICATION Cj/'Y...." ° C; Silty fine to medium sand -brown -firm -moist o -~---_. --._".-.-.---~------- Silty fine to medium sand -tan -firm to dense - moist 1 C 109.4 6.8 83.3 ,---. ----.. --~. _. ---'"--._----~-.----* .. -------------. -_.-. --. -.- Silty fine to medium sand -reddish brown -firm ,--moist 5 - - - --- .;. " i'''' , 10 - - - - ( - 15 -. - - - - 20 - - - - - 25 FIGURE NO. 4 DATE DRILLED 12-28-79 Depth In Feet o --. 1 B . - 5 - 108.9 5.3 85.4 ----.----.-------+---l - - 10 - - - - - 15 - - - - - 20 - - - - - 25 DUCO Engineering, Inc. LOG OF BORING NO. 4 PROJECT NO. 9-277 FJELD CLASSIFICATION Sil ty fine to medium sand ,.., brown --firm -moist Material becomes reddish brown 1n color ~-I . ';.~ - FIGURE NO. 5 DATE DRILLED 12-28-79 Depth In Feet o - . - 5 - 1 --- - - - 10 - - - - - 15 - - - . - 20 - - - - - 25 A 109.8 6.3 ------------ 81.5 ----- DUCO Engineering, Inc. LOG OF BORING NO. 5 PROJECT NO. 9-277 FlELD CLASSIFICATION . Silty fine to medium £and -brown -fairly soft - dry Gravel leach line @ ·2 feet Material becomes reddish brown in color -firm - moist FIGURE NO_ 6 Sob .ckey GeotecBAical Incorporated 32145Via Carlos P.O. Box694 San Juan Capistrano, California Duco Engineering 1170 Centre Suite F Walnut, California 91789 Attention: Mr. Ron Cobine (714) 496-6102 January 2~ 1980 Subject: Geologic Review of Proposed Carlsbad Tract 76-6, Royal Home~ No.7, Syme Drive at Chinquapin Avenue. Carlsbad, County of San Diego. (Duco Engineering Project No. 9-27-7) Dear Sir; This report has been prepared at your request to provide geologic data for design and construction of the subject tract in Carlsbad. Work for this study has included an office review of pertinent published geologic literature" fi.eld reconnaissance of the site, review of trench logs by Duco, and report, preparation. This study has been based upon the 40-scale Grading Plan for Carlsbad Tract No. 76-6 dated November 30, 1979. Geologic Findings The subject tract is considered to be geologically feasible for develop- ment as planned, provided the recommendations of this and the s,")ils engineers report are considered during construction. 1) No bedrock is present on or near the property. Eocene sands have been projected at depth beneath the site. These are not significant to the development. 2) Surficial materials on the property consist of silty fine ~o medium grained sands which have been designated as Quaternary terrace deposits. These materials are probably marine in origin. They were-penetrated to depths in excess of ten feet. The s~ds are quite massive. with no significant geologic struCture. 3) No geologic hazards, such as faults. landslides, mass wastage, accel- erated erosion, soil slumps or groundwater were encountered on or near the site. Ground rupture from faulting is unlikely qn the property. Nearby potentially active faults include the South Coast Offshore Fault a few miles off the coast at Car.lsbad and the more distant Chino-Elsinore Fault to the northeast. These faults should be expected to host' earthquakes during the life of the structures. With the relative distances to active faults and the known seismicity record of this region, the _site is probably below average in its exposure to frequency and Royal Homes -Syme live<Duco #9-277) January 2, 1980 Page Two . . severity.of ground shaking. Building design in accordance with normal Zone 3 seIsmic loading values is considere'd to be appropriate'. 4) Grading ,should be in conformance with recommendations of the soils engineer. Further geologic input to this project is unwarranted. Thank you for this opportunity to be of continued service. This study has been conducted in accor'dance with generally accepted practice in the field of Engineering Geology. No further warranty is 'offered or implied. Please call (714) 496-6102 if there are any questions. ' Respectfully submitted, BOB DICKEY GEOTECHNICAL INCORPORATED EG914, RCE26945 Attachment: Topograhic Index Map Dist: Or~ginal to addressee BOB DICKEY GEOTECHNICAL I j i i ',M L < Royal Homes -Sym~rive(DUCO #9-277) January 2. 1980 Page Three TOPOGRAPHIC INDEX MAP scale: \ \ \ ".. \". ',' '~~i', ;; Base map from a portion of San Luis Rey Quadrangle. USGS Floqd Prone Areas Series~ 1971 BOB DICKEY GEOTECHNICAL