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Home My WebLink AboutCT 76-15; Palisades Point Lots 128-130; Soils Report; 1983-12-12- ( ENGINEERING - ,- - - -- - - - - - ~OllX- C0NSLKTANl-S December 12, 1983 W.O. 386905 Mola Development 808 Adams Avenue Huntington Beach, California 92648 Attn: Mr. Chris Christie Mr. John Millet Gentlemen: Subject: Proposed 1.5:1 Fill Slope Lots 128, 129 and 130 Palisades Point Project Carlsbad, California Pursuant to your request, we have investigated the subject area to determine its suitability for accepting the proposed fill. This additional study became necessary when it came to our attention that an existing 1.5:1, thirty (30') foot high slope located at the toe of the proposed slope was placed as a fill during grading of adjacent property. Two items of particular concern are the affects the proposed fill will have on the existing fill slope and the height of the slope at a ratio of 1.5 horizontal to 1 vertical. The scope of this investigation consisted of review of grading records for the adjacent subdivision; drilling, logging and sampling of an exploratory boring; laboratory testing; stability aalculations; consultation with the project geologist, Baseline Consultants; and preparation of this report. Three sources of information regarding placement of the existing fill slope were investigated: public files at the City of Carlsbad; reports by the project geotechnical consultant, Woodward-Clyde Consultants; and records of the project engineer, Rick Engineering. In each case, the information, while helpful, was incomplete. Compaction testing by Woodward-Clyde Consultants show results of ninety (90%) percent or more of the maximum density. 1630-G South Sunk&d St.. Anaheim, Ca. 92806 (213) 852-4710 (714) 634.2092 - - - - - - - - - - - - - - - ‘"*"La "r"rL"plellL Page 2 W.U. ~OOYU~ More detailed investigation required drilling of an exploratory boring to a depth of forty (40') feet to examine the existing fill and under- lying bedrock materials. In summary, the boring encountered ten (10') feet of compacted fill underlain by thirty (30') feet of sandstone bedrock. Densities of core samples in fill when compared to the maximum dry density show a relative compaction of ninety (90%) percent or more. Boring logs are attached and the boring location is shown on Plates A and B. Shear tests results are presented on Plate B and other pertinent data is presented on the attached Boring Logs. Consultation with Baseline Consultants, project geologists, indicates bedrock structures are favorable. Based on the generated parameters, stability calculations were performed and are attached as Plates C through H. Calculations were reviewed and accepted by Baseline Consultants. GRADING RECOMMENDATIONS It is recommended that grading of the subject slope be carried out as depicted on Plates A and B and as described below. A twenty-eight (28') foot wide bench should be established at the toe of the proposed fill, with a tilt-back into the slope of not less than one (1') foot. Bottom materials should be scarified and brought up to approximately optimum moisture. Fill should be composed of sandstone derived material mixed with two (2%) percent cement by weight, and extend vertically from the proposed toe of the slope to an elevation of twenty (20') feet below finish pad grades. Within twenty (20') vertical feet of pad grades, fill may be composed of compacted soil, with the outer slope face composed of sandstone derived material. As fill is placed, vertical benches not less than four (4') feet in height should be cut into the bedrock material. 1630-G South Sunkist Street Anaheim, California 92606 (714) 634-2092 (213) 852-4710 Mola Development W.O. 386905 - Page 3 :- - - - - - - - During construction of lot 130, it will also be necessary to examine the cut at the rear of the lot and at the rear of lot 131 to determine if mudstone bedrock will provide adequate stability. Should adverse conditions such as jointing or low strength materials be encountered, a stabilization fill composed of soil derived from sandstone materials may be necessary. We trust this letter will meet your needs. If there are any questions, please feel free to contact our office. Respectfully submitted: ACTION GEOTECHNICAL CONSULTANTS &&flA/ BRUCE A. PACKARD RCE 13801 VICE PRESIDENT - ENGINEERING GW:ss attachments: Plates A through H Summary Sheets - Boring #I 1630-G South Sunkist Street Anaheim,California 92806 (714)634-2092 (213) 852-4710 - GRADING DETAILS - LAB RESULTS - - ,- - - - - - - - - - - - (‘0 76 dpe .’ -= SHEAR TEST RESULTS LJ-+h B 9 orir, AA. 2 i 3’ 8’ /2’ aye Cemet7f ra’” 35 34 35 35 35 35* \-----L-L...- ,I&4 c 0 400 /OO 550 300 0 /loo * pLa7-E 23 ..~ - - - - - - - - ,-- .~ i- -.~ - - - STABILITY ANALYSIS py/a me ers : f i- %c e /?eq Ld w+ c&x) M0 ti cos Lx ul& # A? ’ A 4’8d 5.f 50 L3 4J9. 0 5/ .5 L/s/ c 620 .o 50.4 33 D 400.0 48.0 a E 44.0 13.7 a3 f 387.5 46.5 w G //a 0 13.2 7 3.7 37.0 e.3 Y3./ /2 .L -%/ 134 /%. 9 +J.Y /f 35.g 36 a7.v ay al.0 aa 5.P’ 6 N.2 86 /.6 20 fc%G? PLATE c STABILITY ANALYSIS - - -. t7.y. = (BL/ 9.vf- 35) f kdf. 55) = , ho 46.0 OK - .- ,_ S/de &ea zd L%J~(k/jlJ~. d" ddco3ff LaL&& -4' . A 39.0 9.7 95 3.3 3.3 20 - d3 /to. 0 /9.2 3 /5./ j/.-J’ 26 c 2m.o 29.0 33 la./ 134 aq D 69.0 8.3 28 7.3 3-9 7 E d62,5 31.5 8/ a.9 /I.3 87 - F BU .o /o./ /5 1.7~ 2.6 a/ 8’tt 9 46,O - - - - - - -- - - .-- - - - - STABILITY ANALYSIS ~‘Lc @A 2) f& 35) f 30 (* 5s) , ,= 15.2 = 2*38 0-c \ l\ \ \ c= 550 p-f B,c,D- gff-35” c= op,sP /“Z 20’ d%CQ Area d M/d&3) c=ie L4k?&lu c%!!H -9’ R 3v.5 4.1 39 3.3 a.5 30 & 35.0 3.6 32 3.1 /.a 7 c k53.0 /B Y . w /d.Z 8.6 29 0 50.0 6,~ a/ 5d a.2 d4 2f. 2 /5.2 &A?-& E - STABILITY ANALYSIS - - - - - - - - AL - - GD Is! = \\ A. ,,l;Yo 35) f (45wJ)fi 55) /n9 d”J-.- r w7 -= /*‘iz OK, @ &c e Afu2 13 at (2l)nS) cd6 Nt)Cb;ld &!,Jo( A 5Y 6.5 50 Y.d 5-o -p/ 15 d $80 33.6 39 ah/ a/./ 27 c J50 3f.8 c?y 3l.f /s/.2 Pm35 0 /5J Ab.0 13 17.5 4.0 /5 f &s q.3 5 Y.3 P.t’ /2 83.9 44.7 STABILITY ANALYSIS - - - - ~- - - Fs I .= & Plko 35) f 09) 6 5501 = / Bti dY../ , d,X. Para m&A=-r5 A,&- Jzf=35O c= 0 --- _ c, 0 - la’= 3s.O c = 5sops~ /“= 20’ J&e a.. * &L &0.5) &Jo timo( d&A4 J2’ /? 90 /o. B 44 7. e 7-5 31 6 /PO d/.6 3/ &x5 j/J w c /OS Id.6 d/ 17, B q-5 /6 0 32,5 3.9 15 3.8 j.0 13 4-z 9 La/ - STABILITY ANALYSIS ,- Fill Sandstone -5edrock - - - - I /- - - - - - Mola Development - - 117 92 0.0 124 97 5.6 94 121 7 295 7 2 S”RF &GE ELEY. Bucket f DUIP. Auger "Dif Dhr, 24” - : d; 8: “ci g: 3; - LOttED~Y Gary Wallace - lE3C-G Scjrh S;%is! S::eel Ar.a:e;m~ Cal:‘j,r..i 51836 (7:4; 634~3092 (213:8:?-4710 8 0 2 4 6 8 0 2 4 ~6 - - -T- fWCt)lEERw: cLrSS~~IC~lIoh’tt*:9,.,,D~ HITE, slightly clayey SAND ill DTTLED WHITE AND REDDISH ROWN, slightly clayey SAND ith BLACK SAND CLAY HITE, slightly clayey ANDSTONE emented Layers @ 18' to 20' ,IGHT BUFF. silty SANDSTONE ith cemenfed lasers, very lense MITE, slightly clayey, ledium to coarse SANDSTONE JGHT BUFF, silty SANDSTONE, lith cemented layers, very iense - P’OJECT LLDLOGICAL oEs:RIFTIO~~ - - - - - - - - -- Mola Development -I- - t rl . L E 22 kg - - 36. 38, 40. - - i I. 2 0 1. 0: Zf se JO -- T BOR!M,t Na. 1 SLarrtE ELCY. Bucket foutp. Auger wD;E DII 24” LOGCED2v Gary Wallace a08 wo. DA7-l SdECT 3869 1114183 P 2 - 153D.G Swttr S-%;s: S::eel Ar.~>~;rn~ Cal”>r,;a 9i~B36 (714: 634-3092 (513: 1352-C71D - - JXITE SANDSTONE Znd @ 40' Jo Groundwater Encountered lo Caving Occurred