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HomeMy WebLinkAboutCT 82-05A; Telescope Point; Soils Report; 1983-08-01- . G-EOC INCORPOFLATED ENGINEERSANDGEOLGGISTS l CONSULTANTS INTHEAPPLIEDEARTH SCIENCES File No. D-2980-JO1 ~Augugust 1, 1983 - - - - I 1 1 - 1 - P - 1 - Westana Builders/Developers 4241 Jutland Drive, Suite 215 San Diego, California 92117 Attention: Mr. Wes Mudge Subject: TELESCOPE POINT CARLSBAD, CALIFORNIA SOIL AND GEOLOGIC INVESTIGATION Gentlemen: ,- I I lb 6 Q-T c3Z-S?4 In accordance with your authorisation and our proposal of June 10, 1983, we have performed a soil and geologic investigation for the subject project. The accompanying report presents the findings from our study and our recommendations based on those findings relative to the geotechnical engineering aspects of developing the project as presently proposed. Should you have questions concerning our report or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON, INCORPORATED (lAJAk--& Andrei E. Farcas RG 3738 u AEF:JEL:lm (6) addressee 1 - 7 a J 4 J J TABLE OF CONTENTS SOIL AND GEOLOGIC INVESTIGATION Purpose and Scope. . . . . . ................ 1 Site and Project Description ................ 1 Field Investigation. . . . . ................ 3 Laboratory Tests . . . . . . ................ 3 Soil and Geologic Conditions ................ 4 Topsoils . . . . . . . . . ................ 4 Alluvium/Slopewash . . . . ................ 4 ,Soil Creep Deposits. . . . . . 5 Marine~Terrace Deposits. . ................ 5 Santiago Formation . . . . ................ 6 Groundwater. . . . . . . . . ................ 7 Geologic Hazards . . . . . . ................ 7 Liquefaction Potential . . . ................ 8 CONCLUSIONS AND RECOMMENDATIONS Page General........................... 9 Grading.. . . . . . . . . . . . . . . . . . . . . . . . . . 10 Slopestability...................... . 11 Foundations. . . . .,. . . . . . . . . . . . . . . . . . . . 12 Concrete Slabs-on-Grade. . . . . . . . . . . . . . . . . . . 13 Site Drainage and Moisture Protection. . . . . . . . . . . . 14 LIMITATIONS AND UNIFORMITY OF CONDITIONS . . . . . . . . . . , . 16 Figure 1, Site Plan. . .~. . . . . . . . . . . . . . . . . . . APPENDIX A Figures A-l - A-4, Logs of Test Borings Figures A-5 - A-8, Logs of Test Trenches APPENDIX B Table I, Moisture-Density and Direct Shear Test Results Table II, Laboratory Compaction Test Results Table III, Expansion Test Results APPENDIX C RECOMMENDED GRADING SPECIFICATIONS GEOCON -- 1 -. I - m - - - - - - - - - - - I - J - II - m - ir File No. D-2980-JO1 August 1, 1983 SOIL AND GEOLOGIC INVESTIGATION Purpose and Scope We have performed a soil and geologic investigation for the proposed residential subdivision. The purpose of our investigation was to evaluate the surface and subsurface soil and geologic conditions at the site and, based on the conditions encountered, to provide recommendations relative to the geotechnical engineering aspects of developing the project as presently proposed. Our investigation consisted of a site geologic reconnaissance, the exca- vation of eight exploratory trenches and the drilling of two exploratory borings. Laboratory tests were performed on selected representative soil samples obtained at various depths in the test trenches to evaluate pertinent physical properties. The conclusions and recommendations that follow are based on an analysis of the data obtained and our experience with similar soil and geologic conditions. Site and Project Description It is our understanding that the 262 acre, irregularly-shaped site located along a narrow ridge oriented approximately north-south between Skyline Road and Neblina Drive in Carlsbad, California will be developed to receive 64 single-family residential lots. One large open space lot is also anticipated. The majority of the anticipated cut and fill slopes will be relatively shallow, however, cut and fill slopes up to 40 feet in height -I- GEOCON INCORPORATED I - . - . . - 1 - . - File No. D-2980-JO1 August 1, 1983 are also proposed. We anticipate that structures will be one- and/or two- story and will be of wood-frame and stucco construction with continuous footings and slabs-on-grade. Recreation areas are also contemplated. Bordering the site to the west and northeast is undeveloped land. The northwesterly, southerly and easterly portions of the site are bordered by residential developments. . - , - 1 1 I . . - 1 - a - Topographically, the site consists of relatively steep-sided divergent ravines separated by narrow ridges with several nearly vertical to vertical bluffs. Elevations on the site range from a high of approximately 32% feet (MSL) at the northwestern corner to a low of approximately 1302 (MSL) along the southern boundary. Natural drainage is presently accomplished through the existing ravines and subsequently through artificial drainage facilities. Vegetation on the site ranges from a moderate to dense growth of chaparral, native weeds and grasses. Man-made features on the site are limited to several dirt roads which cross the property. The locations and descriptions contained herein are based upon a site reconnaissance and review of preliminary development plans prepared by Henry Worley Associates dated February 10, 1982. Should project details vary significantly from those outlined, Geocon, Incorporated should be notified for review and possible revision of recommendations presented herein. - -2- GEOCON File No. D-2980-JO1 August 1, 1983 Field Investigation The field investigation was performed between June 22 and July 26, 1983 and consisted of geologic mapping by our engineering geologist, the excavation of eight investigative trenches and two large-diameter investigative borings at the approximate locations shown on the attached Geologic Map, Figure 1, (end of report, pocket). The borings were advanced to depths ranging from 41 to 60 feet below the existing ground surface. The drilling was accomplished with a rotary type drill rig equipped with a 30-inch-diameter bucket auger. Trenching was performed with a 410 John Deere tractor-mounted backhoe equipped with a 24-inch-wide bucket. During the investigation, the soils encountered in the test excavations were examined, visually classified and logged. Figures A-l through A-8 of Appendix A present the logs of test borings and test trenches which depict the soil types encountered and the locations of samples obtained. Laboratory Tests Laboratory tests were performed in accordance with generally accepted test methods of the American Society for Testing and Materials (ASTM) and other suggested procedures. The maximum dry density, optimum moisture content and shear strength charateristics were determined on remolded represen- tative samples of the probable predominant fill material. In addition, the expansive potential of typical soils was also tested. These test results are presented on Tables I through III of Appendix B. -3- GEOCON a - m _II ga 111 - ai - ’ g# gi gi a’ gt 11 &a Yi r; - ’ && - ’ 21 - II - . L;1’ File No. D-2980-JO1 August 1, 1983 Soil and Geologic Conditions Our geologic mapping, test borings and test trenches indicate that the site is underlain by topsoils, slopewash, alluvium, soil creep deposits, Marine Terrace deposits and the Santiago Formation. The various soil types are discussed below and the approximate area1 extent of each of the soil and/or geologic ~units, with the exception of the topsoils, is shown on the Geologic Map, Figure 1. Topsoils. Topsoils consisting of loose to medium dense, moist to dry, brown to reddish-brown, clayey silty sand and clay were found over most of the site to depths of 1 to 4 feet. Due to their relatively loose condition, the topsoils will require remedial grading during site development in areas where structural fills are proposed. Alluvium/Slopewash. Due to the difficulty in distinguishing between deposits of slopewash or alluvial origin on the site, the combined designation has been used. In addition, only the larger, most significant deposits are shown on the Geologic Map, Figure 1. It should be anticipated that the upper portions of the ravines, as well as some of the natural sloping areas, will also contain some alluvial and/or slopewash deposits. The slopewash deposits are typically composed of loose to medium dense, weakly cemented or cohesionless, clayey sand and cobble that has accumulated near the base of slopes and/or on gently to moderately sloping hillside terrain. The deepest slopewash deposits, which may exceed 15 to .-4- .- -. - File No. D-2980-JO1 August 1, 1983 20 feet in depth, should be expected within the low portion of the site - -. -, _- 1 ~.~ 1 .- 1 J - I .~ # - tJ - a - l u along the eastern property line. The slopewash/ alluvium deposits are generally poorly to moderately consolidated and susceptible to settlement when subjected to an increase in vertical loads as may result from the placement of fill and/or structures. However, it is our understanding that no improvements are planned for the major areas of their occurrence, therefore, no significant remedial grading will be required. Soil Creep Deposits. Soil creep deposits that have accumulated as a result of slow down slope movement of near-surface clayey, organic topsoils and fractured claystones of the Santiago Formation were encountered along the site's southeastern boundary. Due to the their limited extent, it is our opinion that rhe soil creep deposits will not represent a significant constraint for the future development. Marine Terrace Deposits. Relatively recent sandstone and conglomerate deposits overlying the Eocene sediments along a nonconformable contact were found to comprise the hilltops at the site. The grain size distribution within the terrace deposits is variable ranging from very fine, cohesion- less, silty, poorly-graded sands to well-graded, coarse, well cemented sandstones and cobble conglomerate. The hard, well cemented sandstones occur typically above 2952 feet in elevation. Underlying these sandstones, very weakly cemented, cohesionless, silty, fine sands were encountered. Rippability difficulties should be expected within the upper portion of -5- GEOCON INCORPORATED 4, r r r r r r r i il i iI i r r i r r r File No. D-2980-JO1 August 1, 1983 this sequence, however, the need for blasting is considered highly unlikely. The grain size distribution characteristics and lack of significant cohesion render the finely-grained sands of the marine terrace deposits susceptible to erosion, particularly within fill slopes. A well planned and maintained slope planting and irrigation system provided immediately after grading should significantly reduce erosion potential. Based on field data and previous experience, the sandstones within this formation should be suitable for capping building areas which might otherwise contain expansive soils at grade. According to the grading plan provided to us, the majority of the grading operations will be performed within the marine terrace deposits, therefore, it is unlikely that expansive soils will be exposed at finish grades. In addition, these materials typically possess excellent bearing characteristics in both a natural and properly compacted state. Santiago Formation. The Eocene-aged Santiago Formation underlies the marine terrace deposits and consists primarily of fine- to medium-grained, well sorted, light tan, weakly to medium cemented sandstones interbedded with stiff, grayish, light brown siltstones and claystones. This formation is widely known for its inherently weak claystone beds and generally requires slope stabilization measures for cut slopes in the clay rich portions. In addition to possessing relatively low shear strength. the more clayey portions of this formation are highly expansive and typically -6- CmnPnTYT - d i r a r r lj i r 2 i r n 3 ;I ;I i - a I a File No. D-2980-JO1 August 1, 1983 require selective grading or specially designed foundations to nftigate the potential for adverse effects. The general geologic structure apparently is horizontal or dipping gently to the west. It is our understanding that only limited grading within the northeastern portion of the property is being anticipated within the Santiago Formation, hence, the unfavorable geologic conditions discussed above should not adversely affect the proposed development. Groundwater Although groundwater was not encountered during our investigation, the geologic units encountered on the site have permeability characteristics and/or fracture systems that could be susceptible under certain conditions to water seepage. Inasmuch as no springs, seeps, or groundwater occurrences were observed, or are known to occur on the site, it is our opinion that the seepage potential is relatively low. It is our recamxnendation, however, that periodic inspection be made by either our soil engineer or engineering geologist during grading and/or construction for the presence of ground- water. Remedial measures, if any, will then be recommended. Geologic Hazards It is our opinion, based on our site reconnaissance, evidence obtained in the exploratory excavations and a review of published geologic maps and reports, that the site is not located on any known fault trace. In addition, no ancient landslides were observed on the property. Within a -7- GEOCON INCORPOIATED File No. D-2980-JO1 August 1, 1983 limited area near the southeastern corner of the property, soil creep conditions were encountered. As previously mentioned, we believe that this r condition will not represent a significant restraint to site development. i i r 3 YJ r The Rose Canyon Fault zone lies approximately 5 miles to the west of the property, offshore. This fault is considered to be potentially active, meaning that evidences exists for movement within this zone during the Pleistocene age (2 million to ll,OOO+_ years ago) but not during the Holocene age (last ll,OOO+ years). The nearest knownactive fault is the Elsinore Fault zone which lies approximately 24 miles to the northeast. It is our opinion that the site could be subjected to moderate to severe ground shaking in the event of a major earthquake along any of the above ' mentioned faults, however, the seismic risk at the site is not signifi- cantly greater than that of the surounding developments and the Carlsbad r area in general. 3 Liquefaction Potential It is our opinion that due to the high densities of the soils and the lack ri of a high groundwater table, there is no significant potential for seismically induced liquefaction to occur within the subject property .h limits. & -8- GEOCOK LNCORPDRATE~ File No. D-2980401 August 1, 1983 CONCLUSIONS AND RSCOMNENDATIONS General 1. It is our opinion that the site is suitable for the development of the proposed residential subdivision provided the recommendations presented herein are implemented within design and construction. 2. The results of our field observations and laboratory testing indicates that the near-surface soils on the site possess low to moderate expansive potential. It is our opinion that sufficient nondetrimentally expansive soils will be present on the site to cap all building pads. The majority of the lots will be in cut within marine terrace deposits which were found to be of low expansive potential. 3. No springs, seeps or groundwater was encountered during our investiga- .tion or are known to occur onsite. It is, therefore, our opinion that if surface drainage is directed into contained drainage structures, the potential for future groundwater or seepage related problems should be minimal. 4. As previously mentioned, the onsite soils are highly susceptible to runoff erosion. Fill slopes constructed from poorly graded, very fine, silty sands derived from the marine terrace deposits should be planted immediately after the grading operations are completed. -9- GEOCON INCDIPOIATED -.~ ~.. ~.-~ .,._,, I ,_.__. -.-~ ..- ~.~- -~- ..~ J 1 File No. D-2980-JO1 - August 1, 1983 1 - I - 1 - 1 - I .- I -. 1 I I .- a Grading 5. All grading should be performed in accordance .with the "Recommended Grading Specifications" contained in Appendix C and the City of Carlsbad Grading Ordinance. Where the recommendations of Appendix C conflict with this section of the report, the recommendations of this section shall take precedence. 6. Site preparation should begin with removal of all deleterious matter and vegetation. The depth of removal should be such that material to be used in fills is free of organic matter. Material generated during stripping operations and/or site demolition should be exported from the site. 7. Existing topsoils, alluvium and slopewash beneath areas to receive fill, foundations, slabs, pavements and/or other settlement senstive improvements should be removed to firm natural ground. Removal should extend a minimum horizontal distance of at least 5 feet beyond the perimeter of the improvements. 8. All then exposed natural soils which are to receive fill or structural improvements should be scarified, moisture conditioned and recompacted to a depth of 12 inches. i 9. The site should then be brought to final subgrade elevations with structural fill compacted in layers. In general, native site soils are - -lO- -~~__- ,,.. - --_~. d d - 1 - d r - 1 II r - File No. D-2980-JO1 August 1, 1983 suitable for reuse as fill if free from vegetation, debris and other deleterious matter and contain no particles larger than 6 inches in diameter. Layers of fill should be no thicker than will allow for adequate bonding and compaction. All fill (including backfill and scarified ground surfaces) should be compacted to 'at least 90 percent of maximum dry density at optimum moisture or above as determined in accordance with ASTM Test Procedure'D1557-70, Method A or C. 10. Lots which contain cut/fill contact lines in the building pad should have the cut portions of the lot overexcavated to a depth of 30 inches. The overexcavated areas should then be properly filled with nondetrimen- tally expansive soil. 11. If expansive soils are present within 30 inches of pad elevations, they should also be overexcavated to a depth of 30 inches. The resulting excavation should be properly backfilled with nondetrimentally expansive soil. 12. Foundation excavations and prepared subgrades should be wetted as necessary to maintain compaction moisture contents. Slope Stability 13. It is our opinion, based upon the findings of this investigation, that cut and fill slopes constructed at inclinations of 2.0 horizontal to 1.0 vertical, or flatter, will be stable with respect to deep-seated failure to -ll- GEOCON INCORPORATED File No. D-2980-JO1 August 1, 1983 heights of at least 40 feet. Maximum heights were determined by using a factor of safety of 1.5 under static loads and shear strength based on laboratory testing. Foundations 14. The site is suitable for the use of isolated spread footings or continuous strip footings if graded as recommended above. Such footings should be at least 12 inches in width and should extend at least 12 inches below lowest adjacent pad grade. 15. It is recommended that minimum continuous strip footing reinforcement consist of two No. 4 steel reinforcing bars placed horizontally in the footings, one near the top and one near the bottom. 16. The above minimum reinforcement is based on soil characteristics and is not intended to be in lieu of reinforcement necessary for structural considerations. 17. An allowable bearing capacity of 2000 psf may be used for foundations constructed as recommended above. The allowable bearing capacity is for dead plus live loads and may be increased by one-third for transient loads due to wind or seismic forces. 18. As previously stated, in order to minimize the potential for dffferen- tial settlement along daylight lines or cut/fill pads, the cut portion of the pad should be undercut and recoopacted to a depth of 30 inches minimum. -12- GEOCON INCORPORATL~ - 1 J J 1 1. J .- 1 J 1 1 i File No. D-2980-JO1 August 1, 1983 Concrete Slabs-on-Grade 19. Concrete slabs should have a nominal thickness of 4 inches and be underlain by at least 4 inches of clean sand of other suitable soil. Minimal reinforcement should consist of 6x6-10/10 welded wire mesh throughout. Where moisture sensitive floor coverings are planned, an impervious membrane vapor barrier should be utilised and a 2-inch layer of clean sand should be placed between the base of the slab and the membrane to minimise shrinkage cracking and allow proper curing of the concrete. Retaining Walls 20. Retaining wall foundations bearing in the relatively dense marine terrace deposits may be designed for an allowable soil bearing pressure of 3000 psf at a depth of 12 inches below lowest adjacent finish grades. Foundations placed in properly compacted fill soils may be designed for a soil bearing pressure of 2000 psf at a depth of 12 inches below lowest adjacent finish grades. Reinforcement of such foundations should follow the recommendations of the project structural engineer. 21. The earth pressure against project retaining walls will depend upon the degree of restraint, slope inclination of backfill and backfill materials. The following table presents recommended earth pressures for cantilever retaining walls with varying backfill conditions. -13- GEOCON INCORPORATED i iI r .i - 11 - J - J AA File No. D-29GO-JO1 August 1, 1983 Inclination of Backfill Equivalent Fluid Pressure level 30 pcf 2:l 40 pcf Where the retaining wall will be restrained from lateral movement at the top. a uniform pressure of 50 psf should be added to the active soil pres- sure. The above recommendations assume a drained backfill condition with no surcharge loading. 22. The prevention of hydrostatic pressures and the infiltration of water to supporting foundation soils is assumed in the above design criteria. It is, therefore, recommended that the project architect be consulted for appropriate drainage and waterproofing details. 23. Lateral loads may be resisted by “passive” earth pressure. The passive earth pressure against shallow spread-type footings and/or walls poured neat to undisturbed natural soils or in contact with properly compacted backfill, may be considered equal to the forces exerted by a fluid of 300 pcf unit weight. A coefficient of friction of 0.4 may be used between the bases of footings and slabs and the soil for computing resistance to sliding. Site Drainage and Moisture Protection 24. Providing and maintaining adequate site drainage and moisture protec- tion of supporting soils is an important design consideration. Foundation GEOCON INCORPORATED J J, i File No. D-2980-JO1 August 1, 1983 I recommendations presented herein assume proper site drainage will be established and maintained. 25. Under no circumstances should water be allowed to pond adjacent to footings. The site should be graded such that surface drainage flow is directed away from structures and into wales or other controlled drainage facilities. 26. Landscaped areas within parking areas should be designed such that excess irrigation water is positively drained. Ponding of water within these areas could cause localised high moisture within subgrade soil increasing the potential for pavement failure and/or increased maintenance. -15- GEOCON INrnmmnlllPn J: - J - J - 1 J File No. D-29&l-JO1 August 1, 1983 , LIMITATIONS AND UNIFORMITY OF CONDITIONS 1. The recommendations of this report pertain only to the site investi- gated and are based upon the assumption that the soil conditions do not deviate from those disclosed in the investigation. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that planned at the present time, Geocon, Incorporated should be notified so that supplemental recom- mendations can be given. J 2. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the ai - contractor and subcontractors carry out such recommendations in the field. 13 - 3. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, L whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report L is subject to review and should not be relied upon after a period of three - i years. - < -16- L1 GEOCON APPENDIX A 4 -- 4 i - 4 - 4 - 4 ,j i - J 4 - File No. D-2980-JO1 August 1, 1983 m-Pm SAUPLE LOG' * e.wlror,o S-T-r IN MYBER Lx47!ON 4u,m 59 or m‘vsm .54dPLE August 1, 1983 m-Pm SAUPLE LOG' * e.wlror,o IN MYBER Lx47!ON 4u,m 59 or m‘vsm .54dPLE . 0 ._ . 0 ._ : : : ; . . :: : : : ; . . :: ;.,)::I:: . ., ;.,)::I:: . ., . 2- . 2- J:i;~,~~~~: ..:I: J:i;~,~~~~: ..:I: .: .: ::fi:$ . ..'. :I;!{ ::fi:$ . ..'. :I;!{ -4- -4- );. :. :,: 1. );. :. :,: 1. : ; ;: : ; ;: :: .' :: .' \ \ \ \ \ \ - 6- - 6- /j /j /' /' :. : :. : - 8- - 8- -lO- -lO- -12. -12. -14 _ -14 _ -16 - -16 - - - -18 - -22. ---_ - 24- -26- BORING 1 SANTIAGO FORMATION Very dense, damp, tan, coarse, weakly cemented Silty SANDSTONE -- minor SILTSTONE rip-up clasts J-- becomes very coarse with some pebbles f and sparse~cobbles I i,r- unconformable contact I Weathered, moist, light grayish-brown CLAYSTONE with shiny parting surfaces, r- becomes stiff to very stiff I CLAYSTONElSILTSTONE ,r- grades into very dense, massive, moist, whitish-tan, fine Silty SANDSTONE --- Stiff, moist, --- mottled purplish-brown, Silty CLAYSTONE, bedding attitude horizontal - Figure A-l, Log of Test Boring 1 GEOCON INCORPORATED - 1 - 1 I -- I - 1 - I .- 1 - I - - - - File No. D-2980-JO1 August 1, 1983 30 -- BORING 1 CONTINUED 32 - ,34 - stiff, fractured, light brown-gray CLAYSTONE with numerous randomly oriented slickensided shear surfaces, Manganese oxide staining ,36 - minor fault N25'E.80°W 38 - I 40 - grades into light brown, very dense, massive, weakly cemented, very fine, Silty SANDSTONE 42 _ Stiff,-, -- fractured, dark brown 44 - CLAYSTONE with randomly oriented slickensided shear surfaces 46 - / I r- grades into very dense, moist, tan, I weakly cemented, fine Silty SANDSTONE 48 - -:j&---' 50 - .~iiri::;i ..:. .' . . . . . 52 - ::.1::1::1:. ;;$;,:I;': -- --- 54- ' z' Very stiff, hard, lighr brown, Clayey / SILTSTONE/CLAYSTONE, slow drilling / / 56- / / / E 58. / / / 60 / BORING TERYINATED AT 60.0 FEET Figure A-2, Log of Test Boring 1 Continued - GEOCON - I: - 1 - 1 1 - 1 - 1 - 1 - I .- I - - - - - - - - - - File No. D-2980-501 AlrmIl.~t 1 1981 rrrplr Sl”PLE LOO a Pmelairm DEZCRIPT/DN Dl)” YO,S7”#L IN Num.9 IDcdnm &SMma mN*/rr CwrErfr FEE7 OF B/Wsrvl SMW‘Z *..c.fl % w .? BORING 2 0. TOPSOIL Soft, moist, dark grayish-brown, Sandy 2- CLAY SOIL CREEP Soft, moist, tan, sheared Clayey SAND SANTIAGO FORMATION Very stiff, moist, light grayish-brown, Sandy SILTSTONE very dense, massive, tan, medium SANDSTONE bed ------ Stiff, fractured, moist, mottled purplish-gray, Silty CLAYSTONE/ SILTSTONE with shiny parting surfaces and randomly oriented discontinuous sli&kensided shear surfaces 16- grades into very stiff, hard, damp, IIJII I grayish-light brown, Clayey SILTSTONE, 18 - rare minor fractures -c.--- very hard, massive, gray SILTSTONE, slow drilling 22- 24- 26- grades into very dense, massive, moist, ,-- light grayish-tan, weakly cemented, I I medium to coarse-grained, Silty SANDSTONE rLg”re n-2, bug “I lCDL D”LA.LL& L wncmueo next page - - - - - - - - - - - I I- I- I- - I I- File No. D-2980-JO1 August 1, 1983 a-Pm .s.“PLE I” ““A#~~* fE7 .30.- .32- -34- -36s -38 - -4o- -42 - Figure A LOG a wIr,*, OF afP‘E - - ,Eji :., ,.. ..: fj;.$ ($;ii i;jg ,::/;j; :::.._, j$! $ ,‘. ‘.. 1::1q; :::..:...: ,!‘;I;;; ($,;[; - - *efrot,a ~Sfom ,WyIl - .-- - BORING 2 CONTINLIED -- becomes coarse and~very weakly cemented to cohesionless BORING TERMINATED AT 41.0 FEET St Boring 2 Continued GEOCON lNCORPDRATED - I - l a 1 . - . . - a - a - 1 .-. m - I I - m .~. m 1 - rl 1 - I File No. D-2780-501 August 1. 198'3 IN-P“,% LOO a AMmrc.7 OESCmPrmN IN Nuwm Los~I0.v T*,m- D*I uoIsT”m Pa-7 or BlayT) DENslrl cawEN~ SIUP‘E P.C., % “1 0.i ~0 _ TRENCH 1 I" .' :A :..;. . . .:. TOPSOIL 1: ,. . ...; .,..,: Loose, dry, light gray, Clayey SAND/ 2- .,.' :., :'.',.',: :i;:::::: CLAY .::,'.;.::'::.; MARINE TERRACE DEPOSITS 4.. IHl'li:: .\:,.:...:.:: ::I+l:;;: Very dense, hard, moist, reddish-light .:'I ,::: ':I::: brown, well cemented SANDSTONE 6s ~;~j'l:i' i'i$$ SANTIAGO FORMATION Very dense, moist, light whitish-gray, a- ..:. ..::.'.'.; weakly cemented, medium to cosrse- grained, Silty SANDSTONE TRENCH TERMINATED AT 8.0 FEET 0 TRENCH 2 .:.. 1;'. ;,.' ..:.:.: TOPSOIL/SLOPEWASH : .;, 1; :.., Very loose, dry to moist, grayish-brown, 2- y:,;:.. .:..:;:. :.I.'; ...'.,‘.~~':: Sandy CLAY .;. '.'.,‘. . ..) ::..: :,..: 4. '---.---SOIL CREEP, stiff,~moist, highly sheared, fractured, mottled grsyish- / light brown CLAYSTONE 6- 8- 10 _ 12 - TRENCH TERMINATED AT 11.0 FEET rlgure A-3, Log of Test Trenches 1 and 2 GEOCON INCORPOR*TED - I I a 3 1 - al -~ 1 I ii 1 1 1 .-~ ill J 9 As .~, J File No. D-2780-501 August ., 1983 yo _- .2- -4- -6s - 8- _ 0 _- - 2- - 4- -b- _ 8. -10 -- Figure A- Mmfi vm>,,O” WOMV? - SLOPEWASH Very loose, cohesionless, dry, reddish- brown, fine Silty SAND SANTIAGO FORMATION Very dense, moist, pay, weakly cemented Clayey, well graded SANDSTONE .-- t Trenches 3 and 4 TRENCH TERMINATED AT 6.5 FEET SLOPEWASH TRENCH 4 Very loose, dry, cohesionless, dark brown, fine Silty SAND MARINE TERRACE DEPOSITS Dense, orange-red, moist, very weakly cemented, very fine Silty SAND -- becomes very dense, hard, slow trenching \ TRENCH TERMINATED AT 5.5 FEET JI GEOCON INCORPORATED,, - m 4 I I - I ,- i - I .~ I - I I i ..~ i - i - II - Jll - 3 J -. Ll - II ml - il File No. D-2780-501 Auaust 1. 1983 Awr” SAYP‘C IN NllM8EA mr _ 2- -4 _ 5-l -6s v8- - 2. -4- -6. L- LOG * mno, OF WIP‘C - UIOI n&m ,.WVr m <.:, .:y :.;.:.. : : .y:’ ‘?: * ,,. ., :A:..: (,‘, , .:*;;,-; :/. :.y:, ‘.‘. :: . . :.. ./- m - TRENCH 5 MARINE TERRACE DEPOSITS Dense, moist, orange-red, well graded, weakly cemented massive, Clayey SANDSTONE -- becomes very dense, medium cemented, slow trenching TRENCH TERMINATED AT 6.5 FEET TRENCH 6 TOPSOIL Very loose, dry, reddish-dark brown, Clayey SAND \ MARINE TERRACE DEPOSITS Very dense, moist, orange-red, well graded, coarse, medium cemented, Clayey SANDSTONE 1 TRENCH TERMINATED AT 5.5 FEET DRY DENS,*l AC.! Figure A-7, Log of ‘Lest ‘l‘renches 5 and b GEOCON INCORPORATED - IL r - 4 - 4 -~. J - J - J - 1 - J - J 1 - J 111 - 1 - J - 1 J - _i - J La # -1 August 1, lY8J IN-P‘ICE Plw SIMPLE Lob d PmQlmt.m DESCRIP7,ON 'N NUMBER mnmd 4wsmTa Der Mo,*~uRE ET OF Bb.r/ll o.%.smr c&vrEtu SAMP‘E .?.-.I % sry "i 0. TRENCH 7 j,~.ji~:ji; MARINE TERRACE DEPOSITS :.:~j:i.f Loose, cohesionless, dry, yellowish- 2- ..;..: :I' light brown, very fine Silty SAND :.y.: !:'!I; 4- ..:,..---_- --grades into dense, moist, cohesionless, very fine Silty SAND b- - 7-l 8- y,;:!{:j$ :. ., .i.):(ii:; LO - TRENCH TERMINATED AT 10.0 FEET O- TRENCH 8 i':j:ii:ir) SLOPEWASH ., ,. .::I; !;.!i'; Very loose, moist, dark brown, very 2 - fine Silty SAND :.',jliif:', :,,. . ...:. 4- i;l:jJ;:ij; --_--- becomes wet 6. ;:i:j~,,~:- : :.,:, : ;: : ;,:i,; :,:l: .: .,:. 8- +l -1 -1 F O- 2. ,-grades into medium dense, wet, : yellowish-light brown, very fine SAND 4. TRENCH TERMINATED AT 13.0 FEET lgure A-E, Log of Test Trenches 7 and 8 File No. D-2780-501 _ _^^^ J - JI GEOCON INCORPORATED APPENDIX B File No. D-2980-JO1 August 1, 1983 TABLE I Summary of In-Place Moisture-Density and Direct Shear Test Results - 1 - 1 - 1 - -I - -II - I - 1 - J - d - 4 - 4 - d - Sample NO. x5-1 *7-1 Angle of Dry Moisture Unit Shear Density Content Cohesion Resistance pcf % Psf Degrees 113.5 10.3 250 32 103.8 13.3 140 33 TABLE II Summary of Laboratory Compaction Test Results ASTM D1557-70. Maximum Dry Optimum Sample Density Moisture NO. Description PCf % Dry Wt. 5-l Reddish-brown, medium to 126.0 11.2 coarse, Silty SANE 7-l Light reddish-brown, fine, Silty SAND 114.6 13.5 TABLE III Summary of Laboratory Expansion Test Results Moisture Content Expansion (+) Before After or Sample No . 5-l 7-1 Test Test Dry Settlement(-) Density Surcharge % % pcf % Psf 10.1 17.9 107.8 -0.3 144 8.9 19.1 103.2 -1.4 144 *Sample remolded to approximately 90 percent of maximum dry density at near optimum moisture content. GEOCON INCORPORATED APPENDIXC i i i b - b i - i - I - I - i i - i i h i .~ II .~ b i ; File No. D-2980-JO1 August 1, 1983 RECOMMENDED GRADING SPECIFICATIONS 1. Ge*el-al 1.1 1.2 1.3 2. 2.1 2.2 2.3 2.4 These specifications have been prepared for grading of Telescope Point located between Skyline Road and Neblina Drive in Carlsbad, California. They shall be used only in conjunction with the soil report for the project dated August 1, 1983 prepared by Geocon, Incorporated. The contractor shall be responsible for placing, spreading, watering, and compacting the fill in strict conformance with these specifica- tions. All excavation and fill placement should be done under the observation of the Geocon, Incorporated. Geocon, Incorporated, should be consulted if the contractor or owner wishes to deviate from these specifications. The grading should consist of clearing, grubbing, and removing from the site all material the Soil Engineer designates as "unsuitable"; preparing areas to be filled; properly placing and compacting fill materials; and all other work necessary to conform with the lines, grades, and slopes shown on the approved plans. Preparation of Areas to be Graded All trees and shrubs not to be used for landscaping, structures, weeds, and rubbish should be removed from the site prior to commencing any excavating or filling operations. All buried structures (such as tanks, leach lines, and pipes) not designated to remain on the site should be removed, and the resulting depressions should be properly backfilled and compacted prior to any grading or filling operations. All water wells should be treated in accordance with the requirements of the San Diego County Health Department. The owner shall verify the requirements. All vegetation and soil designated as "unsuitable" by the Soil Engi- neer should be removed under his observation. The exposed surface should then be plowed or scarified to a depth of at least 12 inches until the surface is free from ruts, hummocks, or other uneven fea- tures that would prevent uniform compaction by the equipment used. GEOCON INCORPOIATED 2.5 Where the slope ratio of the original ground is steeper than 6.0 horizontal to 1.0 vertical, or where recommended by the Soil Engi- neer , the bank should be benched in accordance with the following illustration. NOTES ,.’ FINIS+cGRACE (1) ORIGINAL GROUND ~~~~~~~~:~~TE z) (2) SOIL ENGINEEF( .KEY 8 (NOTE 1) 2.6 3. 3.1 3.2 3.3 3.4 / The outside of the bottom key should be below the topsoil or slopewash 'and at least 3 feet into dense formational ma- terials. After the areas have been plowed or scarified, the surface should be disced or bladed until they are free from large clods; brought to the proper moisture content by adding water or aerating; and compacted as specified in Section 4 of these specifications. "B" should be 2 feet wider than the com- paction equipment, and should be a min- imum of 10 feet wide. Materials Suitable for Use in Compacted Fill Material that is perishable, spongy, contains organic matter, or is otherwise unsuitable should not be used in compacted fill. Material used for compacted fill should consist of at least 40 percent fines smaller than 3/4-inch diameter. The soil engineer.should decide what materials, either imported to the site or excavated from on-site cut areas, ai-e suitable for use in compacted fills; the Soil Engineer should approve any import material before it is delivered to the site. During grading, the contractor may encounter soil types other than those analyzed for the soil investigation. The Soil Engineer should be consulted to evaluate the suitability of such soils. Any material containing rocks or hard lumps greater than 6 Inches in diameter should be placed in accordance with Section 6 of these specifications. The Soil Engineer should perform laboratory tests on representative samples of material to be used in compacted fill. Such tests should be performed to evaluate the maximum dry density and moisture content of the samples. The tests should be performed in accordance with accepted test methods of the American Society of Testing and Materials (ASTM). GEOCON INCORPORATED II- . . - 11 - rl - 11 - rl - 11 - d - i - 11 4 - 4 - d - d - 4. Placing, Spreading, and Compacting Fill Material 4.1 Unless otherwise specified, fill material should be compacted while at a moisture content near the optimum moisture content and tn a relative compaction of at least 90 percent as determined by accepted ASTM test methods. 4.2 Fill materials should be placed in layers that, when compacted, have : a relative compaction in conformance with the project specifications. ;~ .~:,'%ch layer should be spread evenly and mixed tho,roughly to provide .-~ uniformity of materials in each layer. 4.3 When the moisture content of the fill material is less than that recommended by the Soil Engineer, water should be added until the moisture content is as recommended. When the moisture content of the fill material is more than that recommended by the Soil Engineer, the fill material should be aerated by blading, mixing, or other methods until the moisture content is as recommended. 4.4 After each layer is placed, nixed, and spread evenly, it should be thoroughly compacted to the recommended minimum relative compaction. 4.5 The fill should be compacted by sheepsfoot rollers, multiple-wheel pheumatic-tired rollers, or other types of compacting rollers that are capable of compacting the fill at the recommended moisture content. Each layer should be rolled continuously over its entire area until the recommended minimum relative compaction is achieved throughout the fill. 4.6 The fill operation should be continued in layers, as specified above, until the fill has been brought to the finished slopes and grades shown on the approved plans. 4.7 Fill slopes should be compacted by sheepsfoot rollers, by track- walking with a dozer, or by other suitable equipment. Conpaction operations should continue until~ the slopes are properly compacted (that is, in-place density tests indicate a relative compaction of at least 90 percent at a horizontal distance of 2 feet from the slope face). 5. Observation of Grading Operations 5.1 The Soil Engineer should make field observations and perform field and laboratory tests during the filling and compaction operations, so that he can express his opinion whether or not the grading has been performed in substantial compliance with project recommendations. 5.2 The Soil Engineer should perform in-place density tests in accordance with accepted ASTM test methods; such density tests should be made in the compacted materials below the disturbed surface. When results of tests taken within any layer indicate a relative compaction below that recommended, that layer or portion thereof should be reworked until the recommended relative compaction is obtained. d - d GEOCON INCORPORATED 6. 1-~, 6.1 rl 6.2 - 6.3 I! !! 6.4 fl 7. + 7.1 A - P 7.2 F 9 7Q Y 3 9 .la Oversize Rock Placement "Oversize" rock is defined as material that is greater than 6 inches and less than 4 feet in maximum dimension. Material over 4 feet in maximum dimension should not be used in fills; such material should be exported from the site, broken into acceptably sized pieces, used for landscaping purposes, or placed in areas designated by the Soil Engineer and/or approved by appropriate governing agencies. -:The Soil Engineer should continuously observe the placement of over- .L size rock. Oversize rock should be placed in lifts not. exceeding the maximum dimension of the rock, and should be placed in a manner that will not result in "nesting" of the rocks. Voids between rocks should be completely filled with properly compacted (minimum relative com- paction of 90 percent) , fine granular material. Oversize rock should not be placed within 5 feet of finish pad grade, within 10 feet of street subgrade, or within 2 feet of the bottom of the proposed utility lines, whichever is deeper. Protection of Work During construction, the contractor should grade the site to provide positive drainage away from structures and to prevent water from ponding adjacent to structures. Water should not be allowed to dam- age adjacent properties or finished work on the site. Positive drainage should be maintained by the contractor until permanent drainage and erosion control facilities are installed in accordance with project plans. No additional grading the Soil Engineer. shall be done, except under the observation of GEOCON INCORPORATED