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Home My WebLink AboutCT 83-18; CALAVERA HILLS VILLAGE H; PROPOSED CUT SLOPE; 1983-11-034S. C SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 6200 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 280-4321 • P.O. BOX 20627 SAN DIEGO, CALIF. 92120 74-B31 V E L I E WAY PALM DESERT, CALIF. 92260 • TEL -E 346-1070 670 ENTERPRISE ST. ESCONDIDO, CALIF. 92025 • T E L E 746-4544 November 3, 1983 Cesco Development Corporation SCS&T 14112 - 110 West "C'1 Street, Suite 1220 Report No. 3 San Diego, California 92101 • Attention: Mr. Scott Turpin SUBJECT: Buttress Recommendations for Proposed Cut Slope, Calavera Hills Village I, Carlsbad, California. References: 1) "Supplementary Geotechnical Investigation, Calavera Hills Subdivision", by Southern California Soil & Test- ing, Inc., July 29, 1983. 2) "Report of Preliminary Geotechnical Investigation for the Calavera Hills, Areas El, E2, H, I, K and P through Z2", by Southern California Soil & Testing, January 6, 1983. Gentlemen: - In accordance with your request, we have performed an additional geotech- nical study at the subject project. The purpose of this study was to provide recommendations regarding the stability of a proposed cut slope in Village I that is contiguous to the proposed alinement of Elm Avenue. It is our understanding that said slope will extend along Elm Avenue a distance of about 1,560 feet and will have a maximum height of 45- feet. .The anticipated • slope inclination will range from 1.6:1 (horizontal to vertical)-to 1.8:1. S • SOUTHERN CALIFORNIA SOILAND TESTING, INC. S -• 'S • .. SCS&T 14112 November 3, 1983 Page 2 FIELD EXPLORATIONS .. 'Three subsurface explorations were made at the locations indicated on the attached Plate Number 1 on October 20 and 27, 1983. These explorations . . . consisted of two borings drilled utilizing a bucket drill rig and a trench excavated utilizing a rubber-tired backhoe equipped with a 24-inch bucket. The field work was conducted under the observation of our engineering geology personnel. . . The explorations were carefully logged when made. These logs are presen- ted on the following Plate Numbers 6 through 12. Trench numbers 'are con- secutive to those of previous investigations.. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart on Plate Number 5. Inaddition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are presented. The density of granular material is given as either very 'lOoe, loose,, medium dense,-'.dense or very dense. The, consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. . . Distrubed samples of typical and representative soils were obtained and returned to the laboratory for testing. , ' LABORATORY TESTING 41 Laboratory tests were performed in accordance with the generally accepted American 'Society' for Testing and Materials (A.S.T.M.) test methods or other suggested procedures. The results' of these tests are presented on Plates Number 13 through-15..'. , • '• '' ' " '• , ' '. • ' ' . ' • ''' " 'FINDINGS The project site is underlain by Tertiary sediments and associated tap- soils and colluvial deposits The Tertiary materials consist of alternat- • SOUTHERN CALIFORNIA SOIL AND TESTING., INC. . . . . S. : . "•. '"' .' S SCS&T 14112 . S November 3, 1983 '. "' Page 3 thy and i.nterfingering .1 ayers of marine sediments that range from sand- stones through clayey sandstones and si"ltstones to. claystones. The top- soil/colluvial zone is approximately two 'to .three feet thick and is com- prised of sandy, silty clays. Underlying the topsoil/colluvial' zone is a zone characterized by weathered and/or . fractured 'sediments that ranges from approximately three to five feet thick and has apparently been affect- ed by soil creep. A relatively thin (less than one foot and commonly less than one inch) layer of apparently remol'ded clay was encountered during our investigation. This layer has relatively low strength parameters and will require mitigating measures when exposed in final slopes. It is . possible that further investigation may reveal the presence of other, thin weak clay seams at other locations. RECOMMENDATIONS General: Our analysis was based on a maximum anticipated slope ratio of 1.5:1. A slope stability computer analysis utilizing the Simplified Bishop's method was performed on two cross sections with a cut slope at - this inclination and derived from a preliminary' development map prepared by Dale Naegle FAIA, Architecture and Planning, Inc., dated June 1983 (See Plates Numbers 2 and 3). A review of an updated grading plan prepared by Charles W. Christensen and Associates, printed November 2, 1983 indicates • that although the slope heights remain the same the actual proposed inch- nation ranges from 1.6:1 to 1.8:1. No additional slope stability computer O analysis was performed with these .revised slope ratios since flattening the slopes results in higher factors of safety and therefore makes our analysisconservative for the actual conditions. . S Slope Stability: Based 'on the results of •our computer :slope stability analysis, it is our opinion that the proposed cut 'slope should'be buttres- sed in its entirety. The buttress' configuration and dimensions are pro- vided in Plate Number 4. The lower 2,5, feet of the buttress should be 0 SOUTHERN CALIFORNIA SOIL AND TESTING. INC. SCS&T 14112 . November 3, 1983 •. . Page 4 constructed with a select material consisting of native silty sand (aver- age strength parameters. = 350 c = 200 psf). Nonselect material consist- ing of on-site sand, silt and clay mixtures (average strength parameters = 260 , c = 200 'psf) may be utilized for the remainder of the buttress. All buttress materials should be approved by our representative at the site. Subdrain: Two subdrains should be provided within the buttress, one at the intersection with the shear plane zone and one at the bottom of the buttress. The subdrains should consist of a 4-inch diameter perforated plastic pipe encased in at. least 3 cubic foot of crushed rock wrapped on filter fabric. Subdrain locations are provided on Plate Number 4. If you have any questions regarding this letter please contact office. Respectfully submitted, S . . SOUTHERN CALIFORNIA SOIL & TESTING, INC. Charles H. Christian, R.C.E. #22330 Curtis R. Burdett, C.E.G. #1090 CHC:CRB:DBA:mw cc: (6) Submitted S S (1)SCS&T, Escondido S S S S S S • .S 55 5 5 . 5 SOUTHERN CALaFORNIA SOIL AND TESTINO. INC. A SECTION AA 320 310 -- 300 EXISTING GRADE FILL 280 CL Ø=26 C=200 270 I3eeo - 60 CL 0=26 C=206 CL 27 C=400 33 C100 5C 240 - SECTION BB EXISTING GRADE 310 B2 -BUTTRESS 4$r - 300 ,- C=200 FIL.1 • 290 SM 0=38 C=150 - . - CLØ=26c=200 - - - - - 280 -.- - ___________________________________ 270 - 02 Lc?F - - - GRADE - 200 v/PROPOSED 260 - a 0=33 C=1 SG CL Ø21 C=200 - 250 _____ a."\ SOUThERN CALIFORNIA - SOIL & TESTING, INC. - - 2401.- SMS (OA1-E 11-3-83 14112 PLATE NO 3 ( 4 - ELM AVE. NONSELECT FILL - (MIN. C=200 - 0=26) SHEAR FORMATIONA L R DPlPE SUBDRAIN .. SELECT. FILL AREA 1% (NATIVE SIILT.YSAND.S WITH S - \MIIIORCLAYSTONES & SI.LTSTONES, MIS. C=200Ø=35) BUTTRESS CROSS-SECTIGN SOUTHERN CALIFORNIA CALAVERA HILLS UNIT I SOIL & TESTING, INC. BY: SMS • DATE: 11-3-83 JOB NUMBER: 14112 Plate No. 4 - rA. 1 5'I SUBSURFACE EXPLORATION LEGEND UNIFIED SOIL. CLASSIFICATION CHART SOIL DESCRIPTION GROUP SYMBOL TYPICAL NAMES 1. COARSE GRAINED, More than half of material is larger than No. 200 sieve size. GRAVELS CLEAN GRAVELS GW Well graded gravels, gravel- More than half of sand mixtures, little or no coarse fraction is larger than No. 4 GP fines. Poorly graded gravels, gravel sic-:e size but sand mixtures, little or no smaller than 3". fines. GRAVELS WITH FINES GM Silty gravels, poorly graded (Appreciable amount gravel-sand-silt mixtures. of fines) GC Clayey gravels, poorly graded gravel-sand, clay mixtures. SANDS CLEAN SANDS SW Well graded sand,gravelly More than half of sands, little or no fines. coarse fraction is SP Poorly graded sands,gravelly smaller than No. 4 sands, little or no fines. sieve size. SANDS WITH FINES SM Silty sands, poorly graded (Appreciable amount sand and silt mixtures. of fines) SC Clayey sandá, poorly graded sand andclay mixtures. 11. FINE GRAINED, More than half of material is smaller than No. 200 sieve size. SILTS AND CLAYS ML Inorganic silts and very jo I. Liquid Limit CL less than 50 OL SILTS AND CLAYS MH Liquid Limit. CH greater than SO OH HIGHLY ORGANIC SOILS PT 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 low 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. - Water level at time of excavation or as indicated US - Undisturbed, driven ring sample or tube sample - Undisturbed chunk sample B - Oulk sample I SOUTHERN CALIFORNIA +.sc... BOIL &TESTING, INC. CALAVERA HILLS UNIT I I BUO PIVERDALE STREET 4 SAN DIEGO, CALIFORNIA E120 - BY DATE CRB- 10-20-83 JOB NO. 14112 Plate No 5 -10 An i]U 19 i. ,. BORING NUMBER i ' w' z >- w Z. I LU o — . ELEVATION . Z LU LUU) cc (/) z - z << _ U) Z LU - - Z - - - CL LU a. o. - <U) a. -. <-LU a.U)0 U)-.. LU - C3 Q. Q. (I) LU - -. < () . '0 • 4 U) U)40 ' a.-O Z. cr zU w w - CC 0 0 z w (L -J DESCRIPTION a. - 0 o 0- o . - - SM BROWN SILTY SAND (TOPSOIL) HUMID MEDIUM . . .. DENSE - - SC! RED BROWN SANDY CLAY! MOIST MEDIUM CL CLAYEY SAND (WEATHERED DENSE! SANTIAGO FORMATION) STIFF CL GREEN BROWN SILTY CLAY MOIST VERY - . (SANTIAGO FORMATION) STIFF - HARD - . - - DENSE - SM BUFF & YELLOW BROWN SILTY MOIST V 7 ' SAND ' . TO VERY . -. DENSE 8--------- CL MOIST HARD RED BROWN & GREEN BROWN - SILTY SAND 9- 10--' US SM BUFF SILTY SAND MOIST DENSE - TO VERY - 11 DENSE - - - CL GREEN BROWN SILTY CLAY MOIST HARD - - V " - . '• . • - - - SM BUFF SILTY SAND DENSE —t MOIST VERY [ENSE 15 - - 'J\ SOUTHERN 'CALIFORNIA SUBSURFACE EXPLORATION LOG LOGGED BY: CRB DATE LOGGED:10-20-83 SOIL &TESTING, INC. <~ Is, > - - JOB NUMBER: 14112 - Plate No. 6 - - LU . BORING NUMBER 1 -w ..>- - z• w. •• Z. w (1) Z_ i-z. <<o U) Z .T .1- ELEVATION - cc u,z ...• LU CL ui a. oU. U) . -: 4 CO a. - 0 a. <-LU. a. (I,0 I-U)'.- - •. U. a. U) W —. i- 4 Q . .j . 4 (J) U) 4 . . 4 • <00' LUUJ.o - 0 -z 0 w a. -J DESCRIPTION - ci 0 15 0~ CL GREEN BROWNREMOLDED CLAY WITH fl US K TINY ROOTS, INCH THIC .10 16 CL RED BROWN &GREEN BROWN MOIST HARD SILTY CLAY 17- CK . . . 18- - • • . • . . . . . -. -US .. ..•. • .7 21 - :• • ... . . 22- 23- 24 us SM BUFF WITH GREEN TINT SILTY MOIST DENSE . SAND . TO VERY - 25- • . . • . DENSE 26r .. . . J-BAG . . . • . . . - 271 . . . • . . .. 28- 29- 30 SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG Q CU SOIL &TESTING, INC LOGGED BY CRB DATE LOGGED 10-20-81 JOB NUMBER 14112 Plate No 7 — • — t1. ;BORING NUMBER 1 i.u• - -; >- .. w w -. Z cr. LU Z_ — Z. <4 Z . I- >0 .- - , _ ELEVATION cc cc Cl) LU - Z U) cn a.CL <U) 4 -LU a. Cl) 0 - cn— W.- 0u 0. (I) W. - 4 0 -j 4 0 4 Cl) (I) 4 a. 0 < a.z <00 z.Cn WW >. 0 0 cr w a.. -J DESCRIPTION . 0 a. 0 0 o - 0 30- - SM BUFF WITH GREEN TINT SILTY MOIST DENSE SAND TO VERY - . DENSE - - GREEN BROWN SANDY CLAY CL & MOIST T1b7 32- SC GRADING INTO CLAYEY SAND DENSE 33-- - , SM BUFF WITH GREEN TINT SILTY MOIST DENSE .24 SAND .... . TO VERY - 34- . . DENSE • . . - 35 - 36 - . 37- . • . - 38- - 39- 40 - • • : • • • S. • S. - US. 21. - 4 — — • . S. • - 47 • .. • 0 - • - US S - 22. • - .48- - . _________________ S • : • . - BORING ENDED AT 48' : • . SOUTHERN CALIFORNIA . SUBSURFACE EXPLORATION LOG SOIL &TESTING, I NC. LOGGED BY: CRB DATE LOGGED:10-20-83 T.10 > JOB NUMBER: 14112 Plate No. 8 LU a. BORINGNUMBER 2 >-z - 2 LU : W>- - X 'I- LU <' 0' z Z_ -z U) I- 0 - — ELEVATION, , •. cn z LU LU 0. 0. <U). °- - -W 'U), I-U)- LU 00 a Cl) LU <0 O < Cl) < . S 0.0 < 0.z' 4'0X z" ' UJ w r - cr 0 z 0 w Q. -J S DESCRIPTION 5 0 0 cc - 0 0 0 5 0- 0 SM! BROWN TO RED BROWN CLAYEY HUMID MEDIUM - SC SILTY SAND (FILL) , , DENSE - SM! BROWN TO RED BROWN HUMID MEDIUM SC (TOPSOIL) DENSE - SC BUFF CLAYEY SAND (WEATH- MOIST MEDIUM ERED SANTIAGO FORMATION) DENSE 5_______ , - SM BUFF SILTY SAND (SANTIAGO MOIST DENSE S FORMATION) S 5 10— MOIST HARD CL GREEN BROWN SILTY CLAY, CALICHE NEAR CONTACT -US ., S , .. 5 5 12- 13- 14 15- '/\ SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG ;NCU > SOIL & TESTING, INC. LOGGED BY: CRB DATE LOGGED: 10-20-83 JOB NUMBER: '14112 , Plate No. 9 - - BORING NUMBER 2 (U - . 2 U Z w S 1 (U 4 5 5 5 5 S . Z cc w Z. - WU) 4< Z 'o Z cc - > - 0 - — - ELEVATION U, Z w Z Z a. . :5.- S 5 5 4. U) -. 4 - (U r" U, — u 0. U) UJ - 4 J 0 4 S o < U) U) S 0 0 4 0. z 40 CC 0: WW U) >. - cc 0 z 0 w cc o:. —J DESCRIPTION 0. - 0 0 • 0 .15- 0 - CL GREEN BROWN SILTY CLAY MOIST HARD - 16---- • US SC GREEN BROWN CLAYEY SAND MOIST DENSE S S - 5 5 S 5 21---- CL MOIST .HARD - - GREEN BROWN SILTY CLAY 22 S BAG S : 24- 25 5 S S - US 5 7 - 0 5 5 30-- S - - -- Lm S J\ SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG - SOIL & TESTING, INC < ~*U LOGGED BY CRB DATE LOGGED 10-20-8 I >S JOB NUMBER: 14112 . Plate No.10 - - BORING NUMBER 2 -:w uj w. I Ui 4 0 Z Ui Z w - W._U) z <<0 (./) Z - > Q - ELEVATION i- Z ui _ Z - - 0.CL - Cl)(,. - - <(l) 0. -. < - Ui 0.Cfl. LU- 0.- ui - i... <o ...j 0 C/, 0 42 0. Z 00 z Cl) ui Ui0 >. - 0 z 0 w- 0 -J DESCRIPTION 0 0. - 0 0 0 30- 0 CL GREEN BROWN SILTY SANDY MOIST HARD - CLAY 31- 32- 33 SC MOIST DENSE GREEN BROWN CLAYEY SAND TO VERY 34_ DENSE - 35 - SM! LIGHT GREEN BROWN CLAYEY MOIST DENSE - SC SILTY SAND TO VERY 36- DENSE 37- 38- - SM BUFF SILTY SAND DENSE MOIST - TO VERY 39.. 0 DENSE US 10 40- 0• 41-- US CL GREEN BROWN SILTY SANDY HARD MOIST - CLAY. :42 43-- SC MOIST - DENSE GREEN BROWN CLAYEY SAND -- TOVER 0 - DENSE 49 L I IBORING ENDED AT 49' I I I I I SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG Z*U > . SOIL &TESTING, INC. LOGGED BY: CR8 DATE LOGGED:102083 -. JOB NUMBER: 14112 Plate No. 11 5 ~,~A`CL GREEN BROWN SILTY CLAY MOIST VERY STIFF (WEATHERED SANTIAFOR ' 0 6 FORMATION) SM BUFF TO YELLOW BROWN SILTY MOIST, DENSE 7 SAND, APPARENT DIP 5° TO EAST - SOUTHEAST (SANTIAGO 8 FORMATION) CL RED'BROWN AND GREEN BROWN MOIST HARD 9 SILTY CLAY CK VERY THIN REMOLDED SEAM AT 10 9 FEET, APPARENT DIP 4b .TO,60 ' CK TO EAST - SIUTHEAST BAG 11 0 TRENCH ENDED AT 11' 0 0 SOUTHERN CALIFORNIA SOIL & TESTING, INC.' BY CRB DATE 10-27-83 JOB NO. 14112 ' Plate No. 12 DIRECT SHEAR SUMMARY; LL IJ Of Lfl 3 Bl at 16' B2 at 17 0 SAMPLE B] at 16' B2 at 17' 2M 2L - NORMAL STRESS, KSF - ANGLE OF INTERNAL COHESION INTERCEPT DESCRIPTION FRICTION (°) (psf) Undisturbed, Slow Shear 27 400 Undisturbed, Slow Shear 28 250 ~*U SOUTHERN CALIFORNIA SOIL & TESTING, INC. CALAVERA HILLS UNIT I BY: DBA DATE: 10-20-83 J08 NUMBER. 14112 Plate No. 13 ______ 2 I_ 11_ 11RECT SHEAR SUMMARY i.1i 'Id'!!!!ai'' 17iJJ ir It hub..: I. ____ TT,1T 11441 Laff1[IT. B2 at 40' B2 at 22'-24' B2 at 31' 0 2M L 2L - NORMAL STRESS, KSF ANGLE OF INTERNAL COHESION INTERCEPT SAMPLE DESCRIPTION FRICTION (°) (psf) 82 at 22 1 -24' Remolded to 90%, Slow Shear 20 200 Maximum Dry Density: 104.7 Optimum Moisture Content: 20.3 B2 at 31' Undisturbed, Slow Shear. 20 200 82 at 40' Undisturbed 38 150 SOUTHERN CALIFORNIA CALAVERA HILLS UNIT I BY: DBA DATE: 102083 SOIL & TESTING, INC. jo NU MBER. .14 112 Plate No. 14 - DIRECT SHEAR SUMMARY I!•jT11r Ii11 .' T 1111 r ill] dl:::' IT IL Ii'tl1i B2 at 42' 0 2M L 2L NORMAL STRESS, KSF ANGLE OF INTERNAL COHESION INTERCEPT SAMPLE DESCRIPTION FRICTION (°). (psf) B2 at 42' Undisturbed, Slow Shear 28 250 SOUTHERN CALIFORNIA CALAVERA KILLS UNIT I 3YU SOIL & TESTING, INC. BY: DBA DATE: 10-20-83 JOB NUMBER: 14112 Plate No. 15 H