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HomeMy WebLinkAboutCT 73-08; Carlsbad Palisades; Soils Report; 1973-03-03I, 1 ,,, !, I smo.9.g7 SOIL INVESTIGATION FOR THE PROPOSED RANCH0 AGUA HEDIONDA - 63 ACRE SITE CARLSBAD, CALIFORNIA / for ;,. ,..~_ .-~~ '----y &+glas Pacific ,.Corporation PozX OTEce-'60x 1207 San Clemente. California 92672 by WOODWARD-GIZIENSKI & ASSOCIATES Consulting Soil and Foundation Engineers and Geologisis (An Affiliate of Woodward-Clyde Consultants) ! I I I 1~ i i TRAJSMITTAL LETTER SCOPE FIELD INVESTIGATION LABORATORY TESTS TABLE OF CONTENTS Page SITE, SOIL AND GEOLOGIC CONDITIONS Topography and Surface Features Description o-f Soil and Geologic Units Overburden Soils Quaternary Alluvial Deposits Quaternary Terrace Deposits Tertiary Marine Sediments Geologic Structure Mineral Resources Ground Water RECOMMENDATIONS AND CONCLUSIONS LIMITATIONS FIGURE 1 - SITE PLAN FIGURE 2 - LOG OF TEST BORING 1 FIGURE 3 - LOG OF TEST BORING 2 FIGURE 4 - LOG OF TEST BORING 2 6 7 8 8 12 FIGURE 5 - LOG OF TEST BORING 3 FIGURE 6 - LOG OF TEST BORING 3 FIGURE 7 - LOG OF TEST BORING 4 FIGURE 8 - LOG OF TEST BORING 4 FIGURE 9 - LOG OF TEST BORING 5 FIGURE 10 - LOG OF TEST BORING 6 FIGURE 11 - LOGS OF TEST BORINGS 7 AND 8 . . 1 ,,-A., 1 . : ‘: 1 FIGURE 12 - LOG OF TEST BORING 9 FIGURE 13 - LOG OF TEST BORING 10 FIGURE 14 - LOG OF TEST BORING 11 FIGURE 15 - GRAIN SIZE DISTRIBUTION CURVES FIGURE 16'- FILL SUITABILITY TESTS FIGURE 17 - RESULTS OF LOADED SWELL TESTS ATTACHMENT I - STABILITY ANALYSIS ATTACHMENT II - SPECIFICATIONS FOR CONTROLLED FILL WOODWARD - GIZIENSKI & ASSOCIATES CcmSULTlNG SOlI. AND FcI"NDAT,ON ENGINEERS AND GEOLOGISTS An affilinte of W'oniltmrd - Cl& Consolfnnk 3467 K”*tr street San Diego California 92110 “141 224.2911 March 3, 1973 Project No. 73-130 Douglas Pacific Corporation Post Office Box 1207 San Clemente, California 92672 Attention: Mr. Jerry J. Johnston In accordance with your request and letter dated February 1, 7973, we have investigated the existing'soil and geologic conditions at the site of a proposed subdivision to be located on a 63 acre site in Ranch0 Agua Hedionda, Carlsbad, California. The accompanying report represents the results of this subsurface exploration and the laboratory tests, as well as the conclusions and recommendations pertaining to this site. The engineer assigned to this project is Richard P. While of our firm. . WOODWARD-GIZIENSKI & ASSOCIATES RPW/LJL/mf (26) Douglas Pacific Corporation (1) Environmental Impact Profiles Attention: Mr. Bfollansdee \\ . . j , :' ' I' Project No. 73-130 i SCOPE This report describes an investigation of the surface and underlying soil and geologic conditions at the site of a proposed subdivision to be located on a 63 acre parcel in Ranch0 Agua Hedionda. The site is situated between Skyline Road and El Camino Real and east of the terminus of Birch and McArthur Avenues in Carlsbad, Calif- ornia. The purpose of the investigation is to determine the surface and subsurface soil conditions, including the presence and effect of fills, loose or porous soils and potentially expansive soils, the availability of select fill material and the characteristics of exca- vation in the proposed. cut area; to make recommendations regarding grading including any required treatment of fill foundations, loose or porous soils, the potentially expansive soils, the requirement of blasting hard rock, if any, the amount of compaction required in the fills,'and guidelines for the design of cut and fill slopes; to de- terming the most suitable types and required depths of foundations for the support of the proposed structures and the allowable soil 'bearing pressures to be used in the design of the foundations on the compacted fill and natural native soil. In addition, comments on mineral resources, ground water and seismic risk are also presented. It is our understanding that the proposed subdivision is to be limited to residential wood-frame structures supported on con- tinuous footings or a pier and grade-beam foundation with a rai~sed wooden floor or a slab-on-grade floor. At the time of this writing no plans were available designating the proposed grading or layout I of structures. A tentative earthwork distribution plan, a topographic VlOODWARD - GIZIENSKI & ASSOCIATES coNl"LTlMo SOIL ANO Fo"flD*lm~ UICWLII), *no 06OLWlS~ Project No. 73-130 Page 2 I ,' ' , map of the 63 acre site, and a road layout were provided for our studies. A preliminary engineering and geological reconnaissanceaas made on February 5, 1973, the results of wfiich were reported to you in a letter dated February 13, 1973. FIELD INVESTIGATION ; . During the period between February 19 and 21, 1973, four bucket excavations and six small diameter auger test borings were made ranging in depth from approximately 50 ft to 70 ft and 10 ft to 25 ft, respectively, below the ground surface. The bucket excavations were made with a 30-in. diameter bucket auger rig and,the small diameter borings were made with a 6-in. diameter truck-mounted, power auger at the approximate locations shown on the Site Plan, Fig. 1. The test borings were located in the field with the aid of an undated untitled topographic map of the general area provided us by Douglas Pacific Corporation. 1~ The drilling was conducted under the supervision of a project geologist from our firm. Field logs were prepared by the geologist on the basis of an inspection of the samples secured and of / the excavated material. The Logs of Test Borings shown on Figs. 2 through 14 are based on a visual inspection of the s‘amples in the laboratory,~the laboratory test results and the field logs. The . vertical position of each sample is shownon the Logs of Test Borings. LABORATORY TESTS The soils encountered were visually classified and evaluated with respect to strength, swelling and compressibility characteristics, dry density, and moisture content. The classification was substan- tiated by grain size analysis and determination of plasticity character- istics of representative samples of the finer grained soil. Fill . WOODWARD- GIZIENSKI b ASSOCIATES co*s"Lm*~ OOlL UIP m""DA"c.Y IhCmIL*s mo CTOLOC>SR Project No. 73-130 Page 3 suitability tests, including compaction tests, direct shear tests, : expansibility characteristics and grain size analyses were performed on samples of the anticipated predominant fill soils. Strength and compressibility characteristics were evaluated by direct shear and un- confined compression tests on selected relatively undisturbed samples and by consideration of the density and moisture content of the samples and the penetration resistance of the sampler. The geologic character- istics of the soils were also considered in this regard. Expansion characteristics were determined by loaded swell tests on undisturbed ,and compacted samples. The results of the moisture content, dry density, un- confined compression and direct shear tests on relatively undisturbed drive samples are shown with the penetration resistance of the sampler at'the corresponding sample location on the Logs of Test Borings. The results of a grain size analyses are shown on Fig. 15, the results of the fill suitability tests are presented on Fig. 16, and the results of the loaded swell tests are reported on Fig. 18. A slow direct shear test on a recompacted sample of claystone is currently under- way at this time. The results of this test will be forwarded in an addendum as soon as possible. SITE, SOIL, AND GEOLOGIC CONDITIONS Topography and Surface Features - The subject property is located south and west of El Camino Real approximately 2000 ft south of the Chestnut Avenue intersection. The northern part of the western boundary is adjacent to a residential * area along Skyline Dirve and the south end of the property is immediately w WOOOWARD - GIZIEHSKI & ASSOCIATES co**"LTIM fOll AND TouNOATKn4 siCw+TZlf .Lo CrOLOClll¶ Project No. 73-130 Page 4 / I I I I / 1. / , ! I ! / I I ! north of a residenti,al development along Kelly Drive. The site is of moderate to steep hilly topography (side slopes range in inclination between 4 and 20 to 1) between the approximate elevations of 50 and 330 fL(plan datum). The si.te lies on the slopes of an old eroded mesa remnant surface. The slopes are eroded into drainage swales and easterly extending ridges, with minor badland topography present on some of the upper slopes. The lower portion of the site is generally covered by a sparse growth of native chaparral grasses and ground cover. The upper area, above approximate elevation 230 ft, isdefined by an existing old fence line and is generally covered by moderate to heavy chaparral and a ground cover. In the lower elevations of the site,on a relatively flat area next to El Camino Real, a small area exists where offsite fill was placed during grading of an adjacent subdivision. The fill was placed and compaction was observed by Woodward-Gizienski & Associates and a report is currently being prepared to cover this fill. Also. present on the site are several dirt trails and dozer trails with their associated cuts and fills. Description of Soil and Geologic Units Our investigation indicates that the, subsurface materials on the subject site can be divided into four main grpups or units. These are in increasing age: overburden soils, quaternary alluvial deposits, Quaternary terrace deposits, and Tertiary marine sediments. The group designated as overburden soils comprise the residual soil mantle which is generally considered to be nonformational in character. w WOODWARD - GIZIENSKI & ASSOCIATES COWI"LTI"C IOlL ANO *o"*orno~ m4cI*lrlll AND cT.aLow,m Project No. 73-130 Page 5 ’ ! t Overburden Soils A residual soil mantle covers the mesa surface and.side hill areas and has developed over the Quaternary alluvial desposits in the lower portions of the site. This topsoil cover consists of 1 to 3 ft of loose yellow-brown silty sand, overlying the Quaternary terrace deposit, and up to 1 ft of dark brown silty sand underlain by 4 to 5 ft of gray-brown silty to sandy clay, overlying the Tertiary sediments. A 1 to 2 ft cover of brown to dark brown silty sand overlies the Quaternary alluvial deposits in the upper. drainage areas; the lower areas are generally cover- ed by 1 ft of very dark gray-brown sandy clay to clayey sand. Quaternary Alluvial Deposits These deposits are found in the wide drainage areas and the lower part of the site and were present to a maximum depth of 42 ft in Boring 1. The deposits consist of interbedded layers and lenses of silty and clayey sands, silty and sandy clays, and gravel. The upper 6 to 10 ft of the sandy materials are con- sidered loos~e ,and/or porous in nature., The amount of clayey material within the deposits was found to be greater in borings made in the lower part of the site (below elevation 150 ft). Quaternary Terrace Deposits Below the residual soil mantle on the remnants of the old mesa surface, formational soils exist consisting of dense red brown s,;ilty sand with occassional layers and lenses of clayey sand and, gravel. This material is found above an approximate elevation of 260 ft, but has a somewhat irregular contact with the underlying Tertiary sediments due to the undulating surface upon which the terrace materials were' deposited. The probable age of this unit is late Pleistocene. Tertiary Marine Sediments I Below the Quaternary terrace material, the alluvial deposits described above, and extending to significant depths on the site WOODWARD - GIZIENSKI b ASSOCIATES CONSULTIN(I SOIL LNCI Fo"llo."o* ~"SW~LRI AN0 CIOLOCII" ,' Project No. 73-103 Page 6 Y’ j is found interbedded layers and lenses of very dense whitish-gray silty sand, hard gray-green sandy clay, hard brown si?ty.clay, and very dense gray silty to clayey sand. Whitish-gray silty sand occurs directly beneath the terrace material and at depth this material grades into a sandy to silty claystone interbedded with silty and clayey sands. These latter soils underlie the intermediate to lolwer portion of the site and are generally found belob!, an elevation of 225 ft. As indicated in Test Borings 4 and 10, the easterly extending ridges found within the central part of the site are underlain predominately by the clayey and sandy material. The upper sandy portion of this unit is described further north as the Torrey Formation of Eocene Age, which would make the probable age of this unit as Eocene. Geoloqic Structure The Tertiary geologic unit, as observed in the bucket holes and adjacent road cuts, exhibit a homoclinal dip to the west and have an apparent regional dip of approximately 5". Our investigation indicates that there are no landslides or landslide associated features within the property. No faults, shear zones, or other weak structural features,were revealed by our borings or during the reconnaissance of the site. Faulting was observed in a road cut south of the site, but the faults were confined to the Tertiary sediments and exhibit no offset of the Holocene Age residual soil mantle. It is our opinion that no active faults exist on the site. A review of the existing geologic literature, including the Department of Water Resources Bulletin No. 116-2, entitled "Crustal Strain and Fault Movement Investigation," indicates that the closest active fault along which epicenters of Magnitude 4 or greater have . WOODWARD - GIZIENSKI & ASSOCIATES co*I"LTI*a SOlL WD ro"*c..no* r.HCl"E~I, **o cmLocI,ll i,,: , ” . Project No. 73-130 Pwge 7 been recorded is the Elsinore fault zone located approximately 19 miles northeast of the subject site. Our earthquake (active fault) evaluation of the site revealed that, as indicated by C. F. Richter's regionalization map, the Carlsbad area has been historically an area of relatively low activity. Flaps, on which earthquakes Magnitude 5 and over between 1934 and the present, and Magnitude 4 and over from 1934-1961 period (Department of Water Resources Bulletin), revealed that most of the earthquakes have occured some~distance from the property and appear to be associated with known active fault zones. As previously indicated, the closest active fault on which repeated epicenters have occured is along the Elsinore fault zone situated some 19 miles from the subject site. In this regard, the paper prepared by McEuen and Pinckney concludes that based on current available data, "A Richter Magnitude 7.3 earthquake on the Elsinore fault having a statistical repeat interval of 60 years appears to be the 'maximum probable' earthquake for San Diego." For most construc- tion the 'maximum probable' earthquake is recommended for design. Mineral Resources A review of "Mines and Mineral Resources of San Diego County, California," California Division of Mines and.Geology County Report No. 3, 1963, indicates that the mineral resources present on the pro- perty are limited to the upper portions of the Tertiary age sediments which contain a quartz rich feldspathic sandstone. This sandstone is potentially a commercial grade specialty sand. Our field investigation . reqealed that on this site it is of a limited quanity and generally WOODWARD - GIZIENSXI & ASSOCIATES Project No. 73-130 Page 8 is overlain by a thick overburden of terrace materials and soil mantle. Ground Water No ground water was encountered in any of the test borings at the time of excavating. In addition, no springs, water seeps, / swampy or marshy areas, or water loving plants were noted'during our % reconnaissance of the site. Due to the genera7 absence of these features and the elevation of the site above the adjacent valleys, it is unlikely that ground water will be encountered at significant depth ! on the site. 'RECOMMENDATIONS AND CONCLUSIONS Among the items which should be considered in the development of a subdivision are the stability of cut and fill slopes, the volume change characteristics of the soils, the rippability of materials, in I I ,! 1 cut areas, the fill suitability characteristics of the anticipated fill material, and the presence, if any, of potential slide areas. .These factors have been evaluated and our conclusions are the following: (1) The results of our soil and geologic investigation have not revealed any major adverse soil or geologic conditions which would I preclude further development of the site. However, potentially highly expansive soils exist at depths in the Formational soils and selective I. grading may have to be employed in order to arrive at satisfactory I. finish grade soil condition. (2) Our investigation did not reveal the presence of land- slides in areas that were previously suspect as reported in our pre- liminary engineering:geology study. , (3) The ground which will receive fill and/or residential WOODWARD - GIZIENSKI & ASSOCIATES co"l"LIWP IOIL AND rounorno" mu*rrat "wa 5EO1c.04~~ Project No. 73-130 Page 9 , structures will, in our opinion, have an adequate bearing value to ,. safely support the,proposed loads when treated as described in the following paragraphs and in the attached "Specifications for Controlled Fill." Footings for, structures placed on properly compacted nonexpan- sive fill or undisturbed nonexpansive firm native materials may be designed for a soil bearing pressure of 2503 lb/ft' ata'depth of 12 in. below rough lot grade. All footings should have a minimum width of 12 in. It should be noted that San Diego County Building Inspections Department currently requires a minimum depth of 18 in. and a width of 15 in. for footings supporting two-story residential structures unless the footings are structurally designed and special inspection is provided during concrete pouring. (4) The soils on the site range from essentially nonexpan- sive to highly expansive in nature. The formational whitish gray sandstone and the red- brown terrace sands are nonexpansive to low in potential expansion. The topsoils and the clayey soils within the alluvium appear to be low to moderate in potential expansion. The ., claystone portion of the Tertiary sediments are potentially highly expansive in nature. (5) It is recommended that the following table be used as a preliminary guide in designing cut and fill slopes at the subject site. WOODWARD .CIZIENSKt & ASSOCIATES cnIt*"Lllllo SOIL AlID Fo"ND.no* WCIPaLL"1 UC. ELOLccl~m I / ! / I I 1 / I TV Project No. 73-130 Page 10 Allowable Height of Slope Slope Inclination Slope Inclination Material l-1/2 : 1 .2:1 v) : Sandstone Predominate .35 60 5; .u J Predominate Claystone 35 55 Fill Slopes 30 50 The above table is based on a minimum:factor of safety of 1.8 under static conditions as determined by the Janbu method of analysis (Attachment I). Soil parameters used in our analysis are based on the results of direct shear tests performed for this inves- tigation, on similar samples in adjacent areas, and our experience with the formations in the subject area. Higher cut of fill slopes may be allowable, but will require more detailed analysis and possibly additional laboratory tests. In this regard, it is recommended that grading plans be reviewed by our office prior to finalizing. Very often the stability of cut slopes depends on geologic factors. It is further recommended that all cut slopes be ,examined I . during and at the completion of grading to verify geologic conditions. Should adverse conditions such as water seepage, fractured claystone or clay seams become apparent, buttressing may be required. All slopes should be planted, drained and properly maintained to help control erosion. , (6) It is our opinion that the soils in the subject area - I ! WOODWRRD - GlZlENSKl & ASSOCIATES coNI"LllNa sot1 ANm Io"*olno" CHm*LL"s A"0 CEDLml,n Page 11 / Project No. 73-130 , ! can be excavated with normal heavy grading equipmen-t. Our test borings were . drilled to approximate depths ranging from 15 ft to 80 ft without refusal. This indicates the subsurface conditions at the specific locations of the test borings; holwever, based upon the test borings and our experience in similar soils in adjacent areas, no "hard rock" is anticipated on this site within anticipated depth of excavation. (7) It should be anticipated that potentially expansive soils will be encountered in the following areas: (a) Where shallow cut or fills are made in the clayey surface ~soils. (b) Where Tertiary claystone his exposed at finished grade in deep cuts. (c) Where clays within the alluvial deposits are exposed at finished grade in deep cuts. 1 t It is recommended that potentially expansive soils be replac- ed within the entire level pad area to a minimum of 3 ft below rough lot grade with properly compacted~nonexpansive soil available at the site. This will require selective grading and possibly stockpiling of select soils for later use. Low to moderately expansive soils, i.e. the clayey sand portion of the ,topsoils, alluvial soil and ter- tiary sediments, may be utilized at finish grade providing footings and slabs are reinforced. (8) During grading, it is recommended that loose and/or porous surface soils and any existing uncompacted frills, not removed by grading operations be,excavated, replaced and compacted before new fills, footings or slabs are placed. The surface of loose and/or .- WOODWARD - GIZIENSKI & ASSOCIATE! coNl"LII(ID MIL Mm Fo"*D.wo* I"ClNELR, wo TCOLOC,,~ 1.: Project No. 73-130 Page 12 b 7. I i, I I porous materials has a variable thickness, but appears to range from 1 to 10 ft across the site. Due to the anticipated variations in depth of the existing loose materials, the depth of excavation and compaction should be controlled in the field by a qualified soil engineer upon visual examina~tion of the exposed materials. (9) A set of 'Specifications for Controlled Fill" is attached, The recommendations made as a part of this soils report shall become a part of the "Specifications for Controlled Fill". LIMITATIONS The conclusions and recommendations made in this report are based onthe assumption that the soils conditions do not deviate appreciably from those disclosed by the test borings. Uhen grading plans are available, they should be reviewed by our office so that -additional re~commendati.ons may be made, as required. Also, if vari- ations are encountered during construction, we should be notified so that we may make supplemental recommendations, if this should be required. Evaluations and utilizations of soil materials and rock formations for support of structures includes.investigation of the subsurface conditions, analysis, formulations of recommendations and inspections during grading. The soil investigation is not completed until the soil engineer has been able to examine the soil and rock in excavations or cut slopes so that he can make the necessary mcdi- fications, if needed. We emphasize the importance of the soil engineer continuing his services through the inspection of grading, including r construction of fills and foundation excavations. c WOODWARD-GUIENSXI & ASSOCJATES coNS"LTI"~ 501L MuI ro"woInol ENCINrLnY AND CEOLOOSTS >/ ! ! I %.I I ~ 1 ! bring I Dense, aDist, yellox-brokn clayey yellow to Porous to 7' dep-tn Fran 7ft. to SDft. - interbedded with silty fine sand (SW') and sil-ty to sandy clay (&-CH) KxJijun~ dense, dzxrp, gray fine to cnarsn sand (SP) with chunks of clayey sand Partially porous Some layers of clean coarse sand with pebbles and gravel For Legend, see Figure 4. LJ.sG DATD DATD Redid:: - de r I Topsoil Tertiary Sedinsnts 6 I LOG OF TEST BORltiG i 63 ACRE SITE - RANCH0 AGUA HEDIONDA !&WJlRD - GIZIENSKI h ASSOCIATES CQWSULTIKG SOIL b#D FOUNnATrON UIGIHEERS &ND GEOLOGIST3 SAN DIEM. CALlFORnlA OR. BY: ALS i AOPPOX. SCALE: 1' = 5' po0.J fjr). 7?-I30 CK'D BY: ,/.?,I DATE: 3-l-73 I ilPr>i HO: 2 I I i ,. i I 0. 5' IO. 15' 2J)- 25. 30. 357 3 - Y 6 - 7 - 8 9 - IO - Boring 2 b!ediLm dense, rroist, black clayey f $~,~s~~~i 2iv;d-br;;o;ndy Tonsoil (JW:PrXiry Alluvium , Medium dense, rroist, light brow to light yellow-brow silty ~fine sand (S&f) with layers of sandy clay (CL) and 5o(ile clean sand Porous scatter& pebbles zy,d gravel 5: ,~ Interbedded dense, mist, gray clayey fine sand (SC) and hard, ,~ rroist, brwm silty clay (CH) continued on next page For Legend, see Figure 4. l- LOG OF TEST BORING 2 63 ACRE SITE - RANCH0 AGUA HEDIONDA CONSULTIXG SOlL dN0 FOUNOdTION WGINEERS AIiD GEULOGlSrS ~;~ 1 . : / I I ! 1 I~ i I I - bring 2 continued 35 - 4;3- 49 - -T =---------- Kerr saw as tefore LEGEND __---- Tertiary Sedinrnts v DATD = Dry at time of drilling. WC = Water Content in percent of dry weight. DD = Dky Density in pcf. BC = N&ber of blows by 180 pound hammer fall ing 30 inches to drive sampler 12 inches. Sampler Data: ID = 2.0”, OD = 2.5". UCS .= Unconfined Compressive Strength in psf. DS = Direct Shear Test Data: 8 = Angle of Apparent Friction in degrees. C = Apparent Cohesion in psf. LL = Liquid Limit in percent. PI = Plasticity Index. (34) = Group classification s'ymbol in accordance with the Unified Soil Classification System. 4 = Sample Number. LOG OF TEST BORING 2 63 ACRE SITE - RANCH0 AGUA HEDIONDA kXIt%lARD - UILIUIJI\I n - CI7IcxICVI 9 jygg)(-,ATES NEERS AWD GEOLOGISTS COOWSULTI#G SOIL A#0 FOUNDATIOW WGI SAN DIEa). CALIFOR CR. BY: ALS 1 dPPRQX. SCALE: 1"=5 Fw3 J, PO: 73-130 1 I ICK'D au:..'t( I DATE: 3-i-73 I F!CI!QE~ti:::~~.~~_"_. , ) r t ! , .-. , I ‘i @rina 3 0. IO. 15. 20' co- 55- Dense, da?p, red-brr%n silty medium NC= qv clayey sand (SC) Clay bed (~CL) Hard, mist, gray-green sandy clay (CH) Very dense, damp, light gray silty fine sand (%) trace clay Dense, clayey with depth continued on next page Pleistocene Terrace material Tertiary Sediments sandstone with sane clay stone Y .--I- For, Legena, see pigwe it. LOG OF TEST BORING 3 I 63 ACRE SITE - RANCH0 AGUA HEDIONDA COWSULTIWG SOIL Ml0 FOUHDATIOX ENGINEERS A;;D GEOLOGISTS ~ I j I ! , 1 1 / I 1 I I t ! I . 60 65 70 - 75 - 80 - I bring 3 continued ---- --_--_ ---_--- Very dense, dmp, light gray silty Tertiary fine sand (94) For Le@nd, see Figure 4. LOG OF TEST BORING 3 63 ACRE SITE - RANCH0 AGUA HEDIONDA GX#3CbJARD -GIZIEI4SKI & ASSOCIATES CDXWLTIHG SOIL b.YD FDUH3ATlOl! EHGIWEERS AN0 GEOLOGISTS SAN DIESO. CALIFORHIA DR. BY: ALS 1 APPROX. SCALE: I" = 5' 1 p7QJ, HO: 73-130 _~ , I ICX'O BY:~",r 1 DATE: 3-l-13 I ., F!GI!JE po: 6 1~ I / I I / I 1 j TV / I I ! . / 0 5 IO I5 a 25 30 35 'x, Boring 4 Graded Cut Pad Hard, dar;p, light gray-bmm silty clav 1C3) - ‘1 ‘Q tlard, dmp, gray-brow sandy to silty clay (Gl) -lit-- \ Hard, mist, brom silty clay (CH) kw Hard. mist. at-w fine ssndv clav Very dense, mist, light gray silty fine sand (34) Trace clay Very dense, damp, light gray clayey Tertiary Sediments Cl aystone with SOW? sandstone --- continued 0) next page For Legend, see Figure 9. - --- I. LOG OF TEST BORING & 63 ACRE SITE - RANCH0 AGUA. HEDIONDA WXIWARD -GIZIENSKI h ASSOCIATES C~NSJLTIHG SOIL b#o FOUH~ATION ENGINEERS AND GEOLOGISTS SAN DIEM. CALIFORHIA DR. BY: ALS f APPROX. SCALE: 1’1 q jr p’fl J, rip: 7?-1% CK'D BY:~~~';:, D_I_TE;-__ 3-l-73 -. F L&J"- -L-- 1.’ I , / 1 I i I 1 I I 1’ I j I Earing 4 continwl ------- ----- Very dense, damp, light gray clayey Tertiary Sdinents SSndStOX with some mudstone Very dense, rwist, gray silty medium to fine sand (34) chtink of hard clay chtink of hard clay hard clay bed 'Y:~ 'Y:~ p hard clay bed DATD DATD For Legend, see Figure 4. LOG OF TEST BORING '+ 63 ACRE SITE - RANCH0 AGUA HEDIONDA hG0iWARD - GIZIEXKI & ASSOCIATES CONSULTING SOIL AMI FOUNDATION ENGINEERS AXD GEOLOGISTS SdN DIEM. CdlIFOSilA DR. EY: ALS AppR*x. SCALE: I" = 5' F??,~,). 'I?: 73-130 1 I I I / / 1 ! I I I / ?~ 0 5 % IO 2 t 8 e 2 -z 15 z 0 g, z 5 2 20 25 30 34 . Medium dense, waist, yellob.Lbrom silty sand (S4) (Porous) with trace of clay Slightly Porous t4edium dense, moist yello+bro~ silty medium to fine sand (34) Slightly Porats Sane layers of clayey sand (Sp) Dense, moist, brown silty fine sand (%) with chunks of clay (CL) 1/_ g,d Hard, mJist, I_ .,,, n,. (cL) Topsoil Quaternary Alluvium Y - Tertiary Sediments \ Claystone For Legend, see Figure 4. LOG OF TEST BORING 5 63 ACRE SITE - RANCH0 AGUA HEDIONDA hCfIMARD - GIZIENSKI h ASSOCIATES MXSULTING SOIL AYD FOUNDATIOX WGINEERS AND GEOLOGISTS Faring 6 Very loose, moist, black clayey sand (SC1 Porous Loose to medium dense, mist, yellow brchn silty medium to fine sand (SY) sane layers of cl2y (CL) Porous 5 I BC = 30 Very stiff, mist, dark brown s.andy clay (CL) Slightly porous IO I - 6 ~,~ ,:::: EC= 26 ~~~~:, l-$i 'with gravel 15 ~,, Itedium dense, damp, bran clayey sand (SC) Slightly porous 20- 25- Hard, nnist, gray sandy clay (CL) Oense, mist, light gray clayey Oense, mist, light gray clayey sand [SC) &coxing sandier with depth sand [SC) &coxing sandier with depth 'wi th gravel For Legend, s= Figure 4. Topsoil I Tertiar Sedimen s yt I LOG OF TEST BORING 6 63 ACRE SITE - RAtlCHO AGUA HEDIONDA MliSJLTl~G SOIL MD FOUND4TIOI( WGlNEERS AND GEOLOGISTS i __,. -. --. _ _ _ O- 5- 10-- IS-- bring 7 -%xpacted, mist, gray-brow clayey FILL fine sand 1 Hard, rimist, blac!x sandy clay (CL) Old Topsoil slightly porous Kdium dslse, rrc~ist, gray-brow clayey sand (SC) saxe clay chunks slightly -pmus -I_i..----- se, voist, black silty to ne sand fSCl Topsoil Ouaternary Alluvium DATD For Legend, see Figure V. LOGS OF TEST BORINGS 7 AND 8 63 ACRE SITE - RANCH0 AGUA HEDIONDA COHSULTING SOIL AXD FGWDATION EIGIHEERS AND GEOLOGISTS ~~ ,j I I , ) , ! I t / ;;; ,\6” EC= 4 ucs =1765 '7 BC = 26 -$ BC= 19 y Poring 9 Loose, mis~t, gray-brow clayey sand (SC) with layers of sandy clay Topsoil @Jaternary Alluvium kdium dense, dsmp, yellow-brown fine sand (SP) with interbeds of sandy clay hGrave1 :, ': ,,,. ',: Medium dezxe, dailp, gray-brom ,,. clayey .sand ,(SC) scme silty sand 1%) ,,, kdium dense, mist, black clayey sand (SC) to hard sandy clay (CL) For Legend, see Figure 4. I LOG OF TEST EORING 9 63 ACRE SITE - RANCH0 AGUA.HEDIONDA WJMJARD - GIZIENSKI h ASSOCIATES COHSJLlIHG SOIL MD FOUHDATICH EnGl#EERS AHD GEOLOGISTS Sdii DIEGO, CALIFOEYIA APPROX. SCALE: r I ‘TV I I / 1 I / I ! bring IO 111 I V&Y loose. mist, dark brow silty tc kayey sand (&SC) Porous . __- Very stiff, mist, gray-brow sandy Hard, damp, brow sardy clq (CH) BC = 60 BC = 301 - DATD Topsoil Tertiarv Sedimen'ts For Legend, see Figure 4. LOG OF TEST BORING 10. UQDWARD -GIZIENSKt b ASSOCIATES COXSULTli(G SOIL AJD FOU#DATIO!i ENGINEERS AND GEOLOGISTS { I I I I I / / 1. I 1 0. 5. IO. 15. 20' 25‘ . lx= 3 -y VIC = 6 2 DD = II2 ;:q z "3; ,c= 0 I- BC = 31 y BC = 54 -$! brinq II Very Icose, mist, dark brow silty fine sand (W) Porous I\ Dense, dmp, bro,fl to yello+brc+n silty fine sand (S,i-SP) slightly porous Partially cemented with gravel ,- with gravel ,- IClay interbeds Hard, mist, gray-brolm clay (CH) For Legend, see Figure It. Topsoil i Quaternary Alluvium Tertiary Sediments Claystone LOG OF TEST EORIHG II 63 ACRE SITE - RAtlCHO AGU,$ HEDIONDA WH)L%lARD - GIZIENSKI b, ASSOCIATES CCWLTING SOIL AYD FOU!lDATlON EXGIHEERS A:ID GEOLOGISTS SAN DIEGO. CALIFORNIA G?AVEL s.Ano COSELES SILT and CLAY coarse Fix *is. lkdiilr~l Fin3 I Mesh Owning - ins. Sieve Sizes Hydrweter Anzlrsis I I I 1 .3, 2 It ;, , hs IO 16 m 5cso ,EO 80 IS0 m r 3l m IO 80 __ 10.0 5.0 1.0 0.1 0.05 0.01 o.rn5 0.001 GRAIN SIZE IN MILLIHETERS *LL = Liquid Limit *PI = Plasticity index GRAIN SIZE D-ISTRIBUTION CURVES 63 ACRE SITE - RANCH0 AGUA HEDIONDA WOODILJARD - GIZIENSKI h ASSOCIATES ~ CCMULTING SOIL AH0 FOtlHOATlOH EHGINEERS AND GEOLOGISTS SAN OIEGO. CALIFO?tIA DR. ay: as APPROX. SCALE: - - - - PROJ. HO: 73-130 CK'D SY: 1 DATE: 312173 FIC'!X n10: I', ,i : / I / - IW, 3 3 '&IO 110 ml 'l--l I;;~E~~I~~J"' DATA m[ ,= 8. 1 i ' ' '> ' ' 0 I40 low I09 IO 1.0 0.1 0.01 O.ooI GRAII! SIZE I:: NILLIHETERS COsRLES GRAVEL I s,t:io c fclr, i SILT B CLAY PLASTICITY CT,ARACTERISTICS I 2 3 Liquid Limit, -- Plasticity Index. % -- Classification by Unified Soil - -- Classification System CL SWLL TEST DATA I2 3 Initial Dry Casity. pcf - - --. __ _---- Initial Water Content. 5 - _-~ -.-.- -- - _ Percent SheI 1 - -- SPECIFIC GRAVITY ZERO AIR VOIDS CURVES NOTE: Specimen Specimen Specimen I = 2= 3= Sample Its Sanple E-5 Sanple 6-2 IABRMORY 'XWACTI'3'4 TEST IAWRATORY COWACTIWI TEST METHOD: AST!&D 1557-70 FILL SUITABILITY TESTS 63 ACRE SITE - RAliCHO AGUA HEDlOilDA hOOCiJARD - GIZINSKI h ASSOCIATES UWSULTING SOIL AW FCLWATICrY ENGIXEERS ko0 G:OLOG,STS SAW OIEGG, CALIFG%llA fil. BY: ALs (A??ROX. SCALE: - - - PZOJ. Nl,: 73-135 ,;_CX'D BY:,,"-.' jOATE: 3-l-73 FI@!'jE E'I: 16 pa.--:- -.--- ! I ?’ I 1 ’ --- -.-. .^1_- w-11- ---. _. RESULTS GF LCADED WLL TESTS smpl~ Number 8- I IO- 2 lnitizl -r Dry Water knsity Content n I 13.' 16 93 28 Saturatioi 4 85 95 - --- Final Volume Change Dry Water Pressure Air Saturate knsity Content Satumtion Diy pcf $ "i? ps-f - _-_ $ of Initial Heiqh --- .__ 112 15 85 160 -1.6 1.0 68 33 IO3 160 -0. I I 5. I Diameter of Smples: 1.94 inches Height of Smples: 0.528 inches I RESULTS OF LOADED SWELL TESTS '63 ACRE SITE - RAIICHO AGUA HEDIONDA huODk4RD - GIZIENSKI 6 ASSOCIATES COHSULTING SOIL AND FOKiDATION EHGINEERS AND GEOLOGISTS SAN DIECZI, CALIFORNIA OR. BY: ALS iAPF?OX, SCALE: - - - 1 PR&J. )O: 73-130 CX'D Yi:6 ':/ DATE: 3-l-73 FlGII?E 3": 17 ! I t- ! . Project No. 73-130 STABILITY ANALYSIS CUT SLOPE IN PREDOMINANTLY SANDSTONE Assumptions: (1) Maximum height of slopes, H = (2) Maximum slope inclination, (3) Unit v1eigh.L of soil, (4) Apparent angle of internal friction, Y = (5) Apparent cohesion, Q = C = (6) No seepage forces. Attachment I Page 1 of 3 , Case a Case b 60 2:1 _t_ l-$:1 1ZOpcf 120pcf 3O?lZf 3O$lif References: : (1). (2) Analysis: Janbu, N., "Stability Analysis of Slopes with Dimensionless Parameters", Harvard Soil Mechanics Series No. 46, 1954. Janbu, N., "Dimensionless Parameters for Homogeneous Earth Slopes", JSMFD, No. SX6, November, 1967. Safety Factor, F.S. = Ncf 2 yH ,, Where Ncf is the stability No. Case a for slopes with both c and +.. x cf = yHtan4 = C 120 x 35 x tan'35 = 9 B 300 From Figure 10 'of Reference 2 Ncf = 25 25 x 300 F*s* = 120 x 35, - =m 'Case b , ' Xcf = x H tan + = C 120 x3;: x tan 35 =,16.8 N cf = 46 46 x 300 F.s*=120x6D = _ 1.91 WOODWARD. GIZIEIISKI & ASSOClAlf coNr"lTlur lcsL 1.40 ,o"*DlnoY E*GI*Tem, ‘"I) CIOLYEI5 , N ‘! . I p I I , 1 ! ,\ ! I .’ / ) 1 - I I Project No. 73-130 STADILITY ANALYSIS CUT SLOPES IN PREDOMINANTLY CLAYSTONE Assumptions: Attachment I Page 2 of 3 Maximum height of slopes, H = MaXilMill slope inclination, UnVt weight of soil, Y = Apparent angle of internal friction, Q = Apparent cohesion, c = No seepage forces. Case a Case 55 7 l-13;:, 2:l 120pcf 12opc 0 6002&f 64"; References: (1) Janbu, N., "Stability Analysis ~of Slopes with Dimensionless Parameters", Harvard Soil iilechanics Series NO. 46, 1954. (2) -J;,,". a "Dimensionless Parameters for Homogeneous Earth , JSMFD, No: Si"16, November, 1967. Analysis: Safety Factor, F.S. = Ncf -$ k'here Ncf is the stability No. for slopes with both c and Q.. Case a h = yHtan$ 120 x 35 x tan 25 = = cf C 600 3 2g From Figure 10 of Reference 2 Ncf = 13 F-S- = 13 x 600 120 x 35 = 1.86 Case .b , x H tan 9 120 x 55 x tan 25 , Xcf = = 5.13 C 600 N cf = 20 F.S. = 20 x 600 120 x 55 = 1.85 - WOODWARD - GIZIENSKI R ASSOCIATE Co"*",It"C ,aII .*,, *.-","n.<ln" c"a."..a- ..I r.n.-r,c Project No. 73-130 1 , t.‘I ! _. . Attachment I Page 3 of 3 STABILITY ANALYSIS FILL SLOPES Assumptions: (1) E'iaximum height of slop'es, (2) Maximum slope inclinstion, (3) Unit weight of soil, (4) Apparent angle of internal (5) Apparent cohesion, (6) No seepage forces. References: : (1)’ (2) Analysis: Janbu, N., "Stability Analysis of Slopes with Dimensionless Parameters', Har,vard Soil Mechanics Series No. 46, 1954. Janbu, N., "Dimensionless Parameters for Homogeneous Earth Slopes", JSMFD, NO. SiS, November, 1967. Safety Factor, P.S.~= Ncf --!?- yH.. Where Ncf is the stability No. for slopes with both c and 0.. Case a A z yHtan+ = cf 120 x 30 x tari 27 = 4 o8 C 450 ~. . From Figure 10 of Reference 2 Ncf = 15 = 15 x 450 = .- F-S- 120 x 30 1.88. Case b * I = xHtan$ 120 x 50 x tan 27 x = ,= 6 8 cf C 450 N cf = 25 F . s . = 25 x 450 120 x 50 = .1.88 WOODtYARD _ ClZlE~lSXI & ASSOCIAT Cc,NS"LTIN(I IOn A"0 ‘o"*D.rm* I*cI*LIII Ah" CLDLO‘ I. .II. III. _- Project No. 73-130 H~Lacnrileit L I I Page 1 of 4 . . , SPECIFICATIONS FOR COF!TROLLED FILL GENERAL These specifications cover preparation of existing surfaces to receive fills; the type of soil suitable for USE in fills; the control of corn-- pact-ion and the methods of testing compacted fills. It shall be the Contractor's responsibility to place, spread, k!ater and compact the fill in strict accordance with these specifications. A Soil Engineer shall be the Owner's representative to inspect the construction of fills. Excz- vation and the placing of fill shall be under the direct inspection of the Soil Engineer and hc shall give written notice of conformance with the specifications upon completion of grading. Deviations from these speci~?ications v/ill be permitted only upon witten authorization from tlhe Soil Engineer. A soil investigation has been made for this project; any recommendations made in the report of the soil investigation or subsequent reports shall bncom e an addendum to these specifications. SCOPE The placement of controlled fill by the Contractor shall include all clearing and grubbing, removal of existing unsatisfactory material, preparation of the areas to be fil~led, sprea'ding and compaction of fill in the areas to be filled, and all other work necessary to complete the grading of thSfilled areas. MATERIALS 1. Materials for compacted fill shall consist of any material imported or excavated from the cut areas that, in the opinion of the Soil Engineer, is suitable for use,in constructing fills. The material shall contain no rocks or hard lumps greater than 6 inches in size and shall contain at least 40% of material smaller than l/4 inch in size. No material of a perishable, spongy, or otherwise improper nature shall be used in filling. 2. blaterial placed within 24 inches of rough lot grade shall be select material that contains no rocks or hard lumps greater than 6 inches in size and that s,~ells less than 3% i~;hen compacted as hereinafter specified for compacted fill and when subjected to an axial pressure of 160 psf. 3. Representative samples of material to be.used for fill shall be tested in the laboratory by the Soil Engineer in order to determine the maximum density, optimum moisture content and classification of the soil. In addition, the Soil Engineer shall determin e the approximate bearing value of a recon- pacted, ,saturated sample by direct shear tests or other tests applicable to the particular soil. 4. During grading operations, soil types other than those analyzed in the report of the soil investigation may b, 0 encountered by the Contractor. The Soil Engineer shall be consulted to determin- 0 the suitability of these soils. WOOD~~!J?D -GIZIENSKI & ASSOCI Ms"L.tl* L(YL All.2 .o"*mrIcu .*bl*ll"* Ano 010 rl‘“JeLL I”“. Ia-!.I” Page 2 of 4 ~ IV. COXPACTCD FILLS t I I ! - ,l. 2. 3. . General (a) Unless otherwise specified, fill material shall be compacted by the Contractor v;ilile at a moisture content near the optimum moisture content and to a density that is not less than 90X of the maximum density determined in accordance v!;th ASTM Test No. Dl557-70T, or other density methods that will obtain equivalent results. (b) Potentially expansive soils may be used in fills below a depth of 24 inches and shall b.e compacted at a moisture content qreater than the optimum moisture content for the material. Clearinc~ and Preparinq Areas to be Filled - -.__-- (a) All trees, brush, grass and other objectiotiable material shal be collected, piled and burned or othewise disposed of by the Con tractor so as to leave the areas that have been cleared with a nea finished appearance free from unsightly debris. 1 t (b) All vegetable matter and objectionable material shall be removed by the Contractor from the surface upon vrnich the fill is to be placed and any loose and porous soils shall be removed.or compacted to the depth shown on the plans. The surface shall then be pTolv)ed or scarifif:: to a minimum depth of 6 inches until the surface is free from uneven features that would tend,to prevent uniform compaction by the equipmen: to be used. (c) blhere fills are constructed on hillsides or slopes, the slope of the original ground on which the fill is to be placed shall be steppe<: or keyed by the Contractor as sholvrn on the attached figure. The steps shall extend completely through the soil mantle and into the underlyil::: formaticn materials. (d) After the foundation for the fill has been cleared, @lowed or scarified, it shall be.disced or bladed by the Contractor until it i:: uniform and free from clods, brought to the proper moisture content .)I;: compacted as specified for fill. Placinq, Spreading, and Compaction Fill Material (a) The fill material shall be placed by the Contractor in layers t,ll'b- when compacted shall not exceed 6 inches. Each layer shall be spreila! evenly and shall be thoroughly mixed during the spreading to obtain uniformity of material in each layer. (b) Glhen the moisture content of-the fill material is above that specified by the Soil Engineer, the fill material shall be aerated i,,, .by the Contractor by blading, mixing or other s.atisfactory methods l::= the moisture content is as specified. WOODWARD. GIZIENSKI R I"~' CO”I”LIIHC SOL, 1hD FQ”*DlTlO” INElNll .- Project No. 73-130 I. . . Attachment II Page 3 of 4 (c) I:hen the moisture content of the fill material is below that - specified by the Soil Engineer, v;ater shall be added by the Con- tractor until the moisture content is as specified. (d) After each layer has been placed, mixed and spread evenly, it shill be thoroughly,, compacted b, *I the Contractor to the specified density. Compaction shall be accomplished by sheepsfoot rollers, vibratory roller, multiple-wheel pneumatic-tired rollers or other types of acceptable compac.ting equipment. Equipment shall be of such desicn that it :?iTl be able to compact the fill to the specified densi'ty. Co:ilp;ctiofl shall be continuous over the entire area and the equipwnt shall make sufficient trips to insure that the desired density has been obtained throughout the entire fill. (e) Surface of fill slopes shall be compacted and thereshall be no loose soil on the slopes. v. INSPECTION 1. Observations and compaction tests shall be made by the Soi! Engineer during the filling and compaction operations so that he can state his opinion that the fill was constructed in accordance with the specifications '2. The Soil Engineer shall make field density tests in accordance with ASTY Test I!o. D-155G-64-T. Density tests shall be made in the compacted materials below the surface where the surface is disturbed. Mhen these tests indicate that the density of any layer o f fill or portion thereof is below the speci.fi-ed density, the particular layer or portions shall be reworked until the specified density has been obtained. VI. PROTECTION OF UORK 1. During construction. the contractor,shall properly grade all excavated surfaces to provide positive drainage and prevent ponding of water. He shall control surface water to avoid damage to adjoining properties. or to finished work on the site. The Contractor shall take remedial measures to prevent erosion of freshly graded areas and until such time as permanent draina,ge and erosion control measures have been installed. 2. After completion of grading and the Soil Engineer has finished his observations of the work, no further excavation or filling shall be done except under the observation of the Soil .Engineer. WOODWARD - GIZIENSKI & ASSOC[I EOM*YLIt*0 1011 **m ‘o"*L)*',o* E"ClMLRI A*= ctm .- M t !!H .~ .-pm . .&- q .,-- Strip 11s Speci ficd - Original Ground Slope ant?.0 = N E : Slope to be such Sloughing or Sliding does not occur Remove all. Topsoil NOTES The minimum width ‘73’” of key shal.1 be 2 feet wider than the compaction equiprr.ent, and not Less than 10 feet. The outside edge of bottom key shall be below topsoil or loose surface material. Keys are required where the natural slope is steeper than 6 horizontal to 1 vertical, or where spec:ified by Soil Engineer. Note -. -n m.-c__- . _ __r__FTz--- , ” _ WOODWARD - GIZIEMSKI & ASSOCIATES CONSULTlNG SOlI. AND FOUNDATION ENGINEERS *ND GEOLOG,STS AIL diilkre of Wood~cd Cl& C~n~dtd~ 3461 Ku** street San mego California 92110 (714) 224.2'111 October 1, 1973 Project No. 73-130 Douglass Pacific Southwest Corporation Post Office Box 38 Oceanside, California 92054 Attention: Mr. Frederick K. Musser RECOMMENDATIONS FOR BUTTRESSING OF ' SLOPES AND FILL FOUNDATION TREATMENTS CARLSBAO PALISADES CARLSBAD, CALIFORNIA In accordance with the request of Mr. Dick Slayter of Rick Engineering Company, we have made additional slope stability analyses of the subject site. These analyses are based on a review of the latest grading plan provided us by Rick Engineering Company on September 19, 1973. A pre- liminary investigation of the site was made by our firm and the results presented in a report dated March 3, 1973. An addendum letter concerning additional soil studies of the site including additional borings and laboratory tests is dated May 16, 1973. The data in these soil reports provide the basis for our slope analyses. The recent grading plan provided us indicates the following cut and fill slope configurations: Type of Slope Approximate Inclination* Approximate Maximum Height cut l-1/2 to 1 74 ft Fill l-1/2 to 1 60 ft Cut-Fill l-1/2 to 1 67 ft (predominantly cut) Cut-Fill l-1/2 to 1 73 ft (predominantly fill) * In slopes over 50 feet in height a bench is provided at approximate mid-height. I ( Douglass Pacific Southwest Corporation Project No. 73-130 . October 1, 1973 Page 2 Our studies included the establishment of soil parameters for use in slope stability analyses; these parameters are based on laboratory tests contained in the preliminary report, additional laboratory tests (including slow direct shear tests performed under saturated conditions) and our experience with similar soils in adjacent areas. Based on our analyses, we have arrived at revised genera7 slope criteria for the subject site. The criteria is based on a minimum factor of safety against deep-seated slope failure of 1.5 under static conditions. The follow- ing table presents these criteria: Slope cut. cut Fill Fill Material Material 1 I Ha= allowable slope height for Ha= allowable slope height for l-1/2 to 1 inclination l-1/2 to 1 inclination t Sandstone Claystone Compacted fill of any suitable on- site soil Compacted Sandstone 25 ft 50 ftk 30 ft 60 ft * * NOTE: Compacted fill slopes over 60 feet in height should have the outer 50 feet compacted to an average relative compaction of 93percent with a minimum compaction of 91 percent. As an alternate, the slope should be reduced to 2 to 1 inclination. Several of the proposed slopes, according to the most recent grading plan fall outside of the criteria listed above. In addition, several of the cut- fill slopes in our opinion that fall within the height limitations, do not have adequate safety factors against slope failure. These slopes are shown on the attached Site Plan, and recommendatirns for fill foundation treatment and/or buttressing are presented below: Cut Slopes Composed of Claystone over 50 feet in Overall Height It 'is recommended that this entire cut slope be buttressed with compacted sandstone in accordance with the following sketch. ~compattion 15' Mtn. as necessary to achieve adequate / , during construction. WOODWARD. GIZIENSKI & ASSOCIATES CIISYLTIIO JmL ANO ,ou*nAna L”alIIUI **o SiMcu,ls Douglass Pacific Southw2st Corporation ,.' Project No. 73-130 . . .,* October 1, 1973 Page 3 Slopes Composed of Compacted Fill over 30 feet and less than 60 feet in Overall Height. It is recommended that all fill slopes greater than 30 feet in. height be constructed in accordance with the following typical sketch: fill material Excavate and recompacted if claystone in key Remove all overburden from key area for inspectjon .ite compacted Cut-Fill Slopes with Claystone in Cut Portion It is recommended that special treatment be employed in the cut portion of these slopes in accordance with the following sketch: Compacted- s.nr(s+nnn Suitable on site compacted It is~gen.erally recommended that the natural overburden soils be benched through and into formational soils as the fill progresses up slope. In many cases, the stability of claystone slopes will depend on the actual geologic conditions exposed in the slc?e. Criteria to be considered'include intense fracturing, jointing or faultin?, weak clayseams within the claystone, bedding attitudes and water seeps. These criteria can best be evaluated by a geologic examination of.the cuts duri::: "rading. Some of the lower cut slopes, falling within our criteria a?ove, !-a:/ have to be buttressed depending on the presence or absence of the adverse seologic features. , WOODWARD-CIZJENSKI 8 ASSOCIATES co*sYLIt*~ se+, mm rcu*DAno* c*Ol"lrr, At.0 CLOLDc~%~T( _’ Douglass Pacific Southwest Corporation >.', 1 ProJect No. 73-130 ., . - October 1, 1973 ,.',. I :I.. Page 4 In regard to landscaping the slopes, whether a particular species of vegetation would be more suitable than another, can be best determined by the landscape architect. It is recommended, however, that controls be placed on irrigating the slope such that excessive wetting of the slope does not occur that would cause saturation of the outer portions of the slope and possible subsequent sloughing. Careful consideration should be given to the design of the irrigation system such that the possibility of leakage and breakage of water lines are minimized. It is recommended that the lots above slopes be properly drained and/or bermed as required and that no ponding of water occur in the pad near the rear slope. It is recommended that final grading plans be reviewed by our office prior to final submittal. If there are any questions concerning our recommendations above or any other part of the project, please call or write at your convenience. WOODWARD-GIZIENSKI & ASSOCIATES LJL/RPW/mf (4) Douglass Pacific Southwest Corporation Attention: Frederick Musser (2) Rick Engineering Company Attention: Dale Gleed Attachment WOODWARD - GlZlENSXl 6 ASSOCIATES CO*f"LT,*O aa, YID ,w*ol,,oN r*ol*L*"3 A"0 OCOLOLII"