Loading...
HomeMy WebLinkAboutCT 83-19; Calavera Hills Village T; Soils Report; 1989-09-20- - _- - -To CITYOF-E-DEJ?- LnLLmECAZAVERA-T TAMARACRAVENCE CARLSBAD, CALIFOIWIA PREFWED FOR: !lk William Lpn Ccmpany 4330 Id Jolla Village Drive Suite 130 San Diego, California 92122 PREPARED BY: Southem Califomia 5o.i.l and Testing, Incorporated Post Off~ice Box 20627 6280 Riverdale Street San Diego, California 92120 c- - - - - - - - SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 6280 RIVERDALE BT. SAN DIEGO, CALIF. 921zo * TEE 280.4321 * P.O. BOX 20627 SAN DIEGO. CALIF. SZIZD 678 ENTEIIPRISE ST. ESCOND4DO. CALIF. 9zoz5 . TELE 746.4544 September 20, 1989 The William Lyon Company 4330 La Jolla Village Drive Suite 130 San Diego, California 92122 SCS&T 8821142 Report No. 6 SUBJECT: Response to City of Carl&ad Engineering Department Comwnts, Valle Calavera Village T, Tamvack Avenue, Carl&ad, California. m: "Report of Supplemental Soil Investigation, Calavera Hills Villages Q and T"; Southern California Soil and Testing, Inc.; October 6, 1988. Centlanen: In accordance with a request frmn i%. Greg Gallagher, we have provided this report to address consents of the City of Carlsbad Engineering Departnvant regarding the subject report. As part of this report wa have reviewed the grading plans for Village T prepared by Hunsaker and Associates San Diego, Inc. dated June 22. 1989. The majority of the consents relat e to the geology of the site. The purpose of our reference report was to update our "Preliminary Geotechnical Investigation, Calavera Subdivision", dated January 6, 1983. The site geoloqy was discussed in this report, a copy of which is attached herein. The general characteristics of each soil type remain unchanged and can be SOUTHERN CALIFORNIA S0,L AND TESTING, I N c. - - - - - - - - SCS&T 8821142 September 20, 1989 found in said report. Updated items are presented hereinafter. The locations of our subsurface exploration perfomsd at the site to date as wall as the geology mapping of the site has been transferred to the current grading plans and can be found on the attached plates. A geologic cross-section is also attached. Based on a review of the aforementioned grading plans,it is our opinion that the momssndations presented in the preliminary geotechnical report should be inplemented unless new reconmsndations are presented on the supplemental referenced soil report. In such case the supplemntal report zecomnendations should be followed. SITE PRtWAIWCICEi: The bottom of all r-al excavations should be scarified to a depth of 12 inches. Proposed grading plans contemplate the construction of cuts and fills at an inclination of 2:l (horizontal to vertical) or flatter, extending to a maximum height of 25 feet and 46 feet, respectively. It is our opinion that said slopes will possess an adequate factor-of-safety with respect to deep seated rotational failure as well as surficial failure (see attached Plates Number 13 and 14). It is recomended that all cut slopes be observed during construction by a member of our engineering geology staff to ascertain that no adverse or unforeseen conditions are encountered. If necessary, slope stabilization ret-ndations will be provided at that time. It should be recognized that cut slopes constructed in metavolcanic/granitic rack may expose lccalized zones of fractured rock. These areas may require special consideration such as rock anchors. It is recormended that all fill slopes be compacted utilizing a sheepsfoot roller at intervals not exceeding four feet in height. SCS&T 8821142 September 20, 1989 Page 3 MI.STIKFADL,T The northwast trending fault encountered at the site is located at or near the contact between the Eocene-age Santiago Formation and older materials. The only younger mterial overlying the fault are Recent alluvial deposits and/or topsoils which are not faulted. None of the topographic features such as offset drainages or sag ponds com0nly associated with active faulting in California wx-e observed at the site. The available infomation indicates that the fault n-oved subsequent to the deposition of the Santiago Formation (approximately 35 million years ago) but that it has apparently not nrwed during the Holocene Epoch (nest recent 11,000 years). Consequently the fault can be considered to be either inactive or only potentially active according to the criteria of the California Division of Mines and Geology. Subdrain locations are shown on the attached Plates 1 through 11. A subdrain detail is presented on the attached Plate Number 15. A retaining wall s&drain is presented. on the attached Plate Number 16. No groundwater was encountered during our subsurface exploration and wa do not anticipate any major groundwater related problems, either during or after construction. However, it should be recognised that minor groundwater seepage problems may occur after developxsent of a site even where none wxe present before developsent. These are usually minor phenonrana and am often the result of an alteration of the pemxsability characteristics of the soil, an alteration in drainage patterns and an increase in irrigation water. Based on the pemeability characteristics of the soil and the anticipated usage of the developnent, it is our opinion that any seepage problem wfiich my occur will be minor in extent. It is further our opinion that these problesw can be m>st effectively corrected on an individual basis if and when they develop. - - - - - - - - - - - SCS&T 8821142 September 20, 1989 Page 4 If you have any questions regarding this report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, & TESTING, INC. Daniel B. Pdler, R.C.E. x56037 , Curtis R. Burnett, C.E.G. #1090' DBA:CRB:m cc: (3) submitted (3) Hunsaker and Associates San Diegu, Inc. (1) SCS&T, Escondido - - - _- .- - .- -~ - .- - - - LEGEND TRENCH LOCATION (1988) TRENCH LOCATION (SCS6T REPORT l-9-84) TRENCH LOCATION (1982) TRENCH LOCATION (1981) M SEISMIC TRAVERSE LOCATION (1988) c=i SEISMlC TRAVERSE LOCATION (SCS&T REPORT l-9-84) M SEISMIC TRAVERSE LOCATION (1982) w SElSMlC TRAVERSE LOCATION (1973) a BORING LOCATION (1973) *- * -* APPROXIMATE LOCATION OF FAULT Q8l OODI Qu Es TP Kgr/ Jmv JmvlKgr QUATERNARY ALLUVIUM QUATERNARY OLDER ALLUVIUM UNNAMED SANDSTONE EOCENE SANTIAGO FORMATION TERTIARY PALEOSOL CRETACEOUS GRANITIC ROCK/JURASSIC METAVOLCANIC ROCKS JURASSIC YETAVOLCANIC ROCKSlCRETACEOUS GRANITIC ROCKS 8OUTHIRN CALICORNIA CALAVERAS HILLS 8OIL A T~8TINQ,INC. w: DBA/WDW pATEE 9-19-89 JOB WUYDCI): 892’142 PLATE P12 SLOPE STABILITY CALCULATIONS Janbu's Simplified Slope Stability Method \+w , FS-Ncf(+) Assume Homogeneous Strength Parameters throughout the slope 0 (“1 C(psf) W-(pcf) Incl. H (ft) FS 39" 200 132 2:l 30 2.3 42" 200 124 2:l 50 2.3 Where: 0 - Angle of Internal Friction C = Cohesion (psf) Us = Unit weight of Soil (pcf) H = Height of Slope (ft) FS = Factor of Safety 8OUTl48RN CALICORWIA VILLA CALAVERAS VILLAGE T *OIL & T88TIW(I, I NC. FT: DBA DATE: g-20-89 JOI NUYILI): 8821142 Plate No. 13 d .- SURFICIAL SLOPE STABILITY SLOPE SURFACE ASSUMED PARAMETERS z = DEPTH OF SATURATION = 3 ’ a = SLOPE ANGLE = 26.5” iw= UNIT WEIGHT OF WATER = 62.4 pcf 6T= SATURATED UNIT WEIGHT OF SOIL = 144 pcf # = APPARENT ANGLE OF INTERNAL FRICTION ALONG PLANE OF FAILURE = 39” c = APPARENT COHESION ALONG PLAN OF FAILURE = 200 psf FS = c+TTAN(I = c + (XT - ilwb z COS a TAN @ T XT z SIN a COS a FS = 2.2 8OUTHlRN CALIFORNIA VALLE CALAVERAS VILLAGE T SOIL & TI8TIWO,INC. l y: DBA DATE: g-20-89 CANYON SUBDRAIN DETAIL I- DETAIL A FILTER MATERIAL PNTER MATERIAL SHALL BE CLASS 2 PERMEABLE MATERIAL PER STATE OF Ma. 6 1643 , Ma. 30 S-16 PERFORATED PIPE SURROUNDED Ma. SO WITH FILTER MATERIAL No. 200 iz DETAIL OF CANVON SUBDRAIN TERMINAL 6-MIN OVERLAP EQUIVALENT) PERFORATED 4’MIN PIPE I 1 l/P”QRAVEL WRAPPED IN F1LTF.R FABRIC I - SUBDRAIN INSTALLATION:SU~DRAIN PIPE SHALL BE INSTALLED WITH PERFORATIONS DOWN ~~. SUBDRAIN PIPE:SUBDRAIN PIPE SHALL BE PVC OR ABS, TYPE SDR 35 FOR FILLS UP TO 35 FEET DEEP, OR, TYPE SDR 21 FOR FILLS UP TO 100 FEET DEEP SOUTHERN CALIFORNIA CALAVERAS HILLS SOIL 8 TESTING, I NC. - - - - - - - - .-. - - .~. - _- I I ,WATER?ROOf 2ACX Of WALL CL2 s/4 INCtl CRUIHED nocx OR MIRADRAIN 6DDD OR EQUIVALENT QEOfABRIC SETWEEN ROCX AND SOIL 4” DIAMETER CERfORATED CICE .: 3 I /iAD-OM-GRADE , RETAININCI WALL SUBDRAIN DETAIL NO @CALI sOUTW8RW CALlrORnlA VALLE CALAVERAS VILLAGE T SOIL 8 TE8TIWQ*lnc. IV’: DBA Ohtt: g-20-89 JO. WUY~CR: 8821142 Plate No. 16 -, - - - - - - - - - - - - - _- - - - PRELIMINARY GEOTECHNICAL INVESTIGATION CALAVERA HILLS SUBOIVISION CARLSBAU, CALIFORNIA PREPARED FOR: Calavera Hills Company 110 West "C" Street, Suite 1220 San Diego, California 92101 PREPARED BY: Southern California Soil & Testing, Inc. Post Office Box 20627 6280 River-dale Street San Diego, California 92120 - .- - - - - 5G T January 6, 1983 Calavera Hills Company 110 West "C" Street, Suite 1220 San Diego, California 92101 SCS&T 14112 Report No. 1 ATTENTION: Mr. Scott Turpin SUBJECT: Report Hills, ornia. Gentlemen: of Preliminary Geotechnical Investigation for the Calavera Areas El, E2, H, I, K and P Through 22, Carlsbad, Calif- In accordance with your request we have performed a preliminary geotech- nical investigation for the subject project. The findings and recommenda- tions of our study are presented herewith. In general, we found the site suitable for the proposed development pro- vided the recommendations presented in the attached report are followed. If you have any questions regarding this report, or if we may be of fur- ther service, please do not hesitate to contact our office. Very truly yours, IL & TESTING, INC. Charles H. Christian, R.C.E. #22330 CHC:CRB:DBA:mw CC: (6) Submitted (1) SCS&T, Escondido SOUTHERN CAL(FORN,A SOIL ANO TESTING. ! N c. - - - - - - ,-- - _,~ - - - - - TABLE OF CONTENTS PAGE Introduction and Project Description ..................................... 1 Scope of Service ......................................................... 3 Findings ................................................................. 4 Site Description ..................................................... 4 General Geology and Subsurface Conditions ............................ 5 Geologic Setting and Soil Description ........................... 5 Jurassic Metavolcanics and Cretaceous Granitics (Jmv/Kgr) .. ...5 Lusardi Formation (Kl) ..................................... ...7 Tertiary Paleosol (Tp) ........................................ 7 Santiago Formation (Es) ....................................... a Tertiary Volcanic Rock (TV) ................................... 8 Quaternary Sandstone (Qu) ..................................... 9 Older Quaternary (Pleistocene) Alluvium (Qoal) ............. ...9 Younger Quaternary (Holocene) Alluvium (Qyal) .............. ...9 Artificial Fill (Qaf) ......................................... 9 Geologic Conditions for Proposed Villages......................1 0 Tectonic Setting ............................................... 12 Geologic Hazards ............................................... 12 Individual Area Characteristics ................................ 13 Seismic Survey and Rippability Characteristics .......................... 13 General ........................................................ 13 Rippability Characteristics of Granodioritic Rock...................2 2 Rippable Condition (O-4,500 Ft./Set.) .......................... 22 Marginally Rippable Condition (4,500 . 5,500 Ft./Sec.).........2 2 Nonrippable Condition (5,500 Ft./Set. & Greater)...............2 3 Rippability Characteristics of Metavolcanics and Associated Hypabyssal Rocks and Tonalitic Rocks .............................. 23 Rippable Condition (O-4,500 Ft./Set.) .......................... 23 Marginally Rippable Condition (4,500 . 5,500 Ft./Sec.).........2 4 Nonrippable Condition (5,500 Ft./Set. & Greater)...............2 4 Rippabi.lity Characteristics ......................................... 24 Rippability Charts ............................................. 24 - - - - - - - - - - .~. - - - - TABLE OF CONTENTS (continued) PAGE Seismic Traverse Limitations ........................................ 25 Recommendations and Conclusions ......................................... 26 General ............................................................. 26 Site Preparation .................................................... 26 General ........................................................ 26 Subdrains ...................................................... 27 Rock Disposal .................................................. 27 Select Grading ................................................. 28 Undercutting ................................................... 28 Earthwork ...................................................... 29 Slope Stability ..................................................... 29 Slopes for Access Roads ........................................ 29 Additional Slopes .............................................. 29 Foundations ......................................................... 30 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Reinforcing .................................................... 30 Concrete Slabs-on-Grade ........................................ 31 Settlement Characteristics ..................................... 31 Expansive Characteristics ...................................... 31 Earth Retaining Structures .......................................... 32 Ultimate Passive Pressure ...................................... 32 Ultimate Active Pressure ....................................... 32 Backfill ....................................................... 33 Factor of Safety ............................................... 33 Limitations ............................................................. 33 Review, Observation and Testing ..................................... 33 Uniformity of Conditions ............................................ 34 Change in Scope ..................................................... 34 Time Limitations .................................................... 34 Professional Standard ............................................... 35 Client's Responsibility ............................................. 35 Field Explorations ...................................................... 36 Laboratory Testing ...................................................... 37 ATTACHMENTS FIGURE -- - - - - _- PAGE Figure 1, Site Vicinity Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 TABLES Table I, Generalized Engineering Characteristics of Geologic Units......1 0 Table II, Geologic Conditions for Proposed Villages.....................1 1 Table III, Seismic Traverses ......................................... 14-17 Table IV, Soil/Rock Conditions Anticipated...........................18-2 2 PLATES Plate 1 Plate 2 Plate 3-55 Plate 56 Plate 57 Plate 58 Plate 59-62 Plate 63 Plate 64-65 Plate 66 Plate 67 Plate 68 Plot Plan Unified Soil Classification Chart Trench Logs Maximum Density & Optimum Moisture Content Direct Shear Test Results Expansion Test Results Grain Size Analysis and Atterburg Limits Single Point Consolidation Test Results Seismic Results Typical Canyon Subdrain Cross-Section Oversize Rock Disposal Slope Stability Calculations APPENDICES Appendix A, Plates From Previous Report Appendix B, Recommended Grading Specifications and Special Provisions - - - - - .- - - .- - - PRELIMINARY GEOTECHNICAL INVESTIGATION CALAVERA HILLS SUBDIVISION CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of our preliminary geotechnical investiga- tion for areas El, E2, H, I, K, and P through 22 in the Lake Calavera Hills Subdivision, located in the City of Carlsbad, California. The site location is shown on the vicinity map provided as Figure 1. It is our understanding that the site will be presently developed by the construction of access roads such as College Boulevard, Elm Street and Tamarack Avenue. Individual parcels will be later engineered and sold for future development. Although no specific plans exist at this time, com- mercial and residential developments may be anticipated. Grading for access roads will consist of cuts and fills on the order of 255 feet and 40+ feet, respectively. Proposed cut and fill slopes with an inclina- tion of 2:l (horizontal to vertical) will not exceed 30+ feet and 65+ feet in height, respectively. To assist in our investigation, we were provided with two undated topo- graphic maps, improvement and grading plans for Tamarack Avenue (Stations 56+08 to 66+50), Elm Street (Stations 66+50 to 83t81) and College Boule- vard (Stations 82+47 to 91+32), dated January 14, 1980; and an amended master plan dated March 23, 1979. The plans were prepared by Rick Engi- neering Company. In addition, the following documents were reviewed: SOUTHERN CALIFDRNIA s 0 I L AND TESTING. I N 0. -~ ,- - I SOUTHERN CALIFORNIA SOIL & TESTING, INC. . ..0 rn,“ZIIDALI m-?m.rr rnAN 01mm0. CPLIEOr)NII a.,mo Calaveras Hills Carlsbad, California BY DATE SMS 8-6-84 JOB NO. 14112 Figure No. 1 I - SCS&T 14112 January 6, 1983 Page 3 - 1) - 2) -- - 31 - - - - 4) 5) "Soils Engineering and Engineering Geologic Keconnaissance Inves- tigation, Calavera Hills Property", April 29, 1981, Earth Re- search Associates, Inc. Appendix A of Report, San Diego Soils Engineering, Inc., February 18, 1981. "Preliminary Geotechnical Investigation for the Proposed Lake Calavera Hills Units C and A and a Portion of the Extension of Glascow Road", June 30, 1980, Woodward-Clyde Consultants. "Pre-Preliminary Investigation for the Calavera Country Develop- ment", June 7, 1973, Southern California Testing Laboratory, Inc. Related correspondence in our files. Where pertinent, information from said reports was incorporated to this study. The site configuration, approximate topography and location of our subsur- face explorations are shown on Plate Number 1 of this report. SCOPE OF SERVICE This investigation consisted of: surface reconnaissance; seismic refrac- tion survey, subsurface explorations; obtaining representative disturbed and undisturbed samples; laboratory testing; analysis of the field and laboratory data; research of available geological literature pertaining to the site; and preparation of this report. Specifically, the intent of this analysis was to: a) Explore the subsurface conditions to the depths influenced by the anticipated construction. SOUTHERN CALIFORNIA SOIL AND TESTINGr. lWC - .- - - - - SCS&T 14112 January 6, 1983 Page 4 b) cl d) e) f) Evaluate, by laboratory tests, the pertinent engineering pro- perties of the various strata which will influence the develop- ment, including their bearing capacities, expansive characteris- tics and settlement potential. Define the general geology at the site including possible geo- logic hazards which could have an effect on the site develop- ment. Evaluate the rippability characteristics of metavolcanic and granitic rock underlying most of the site. Develop preliminary soil engineering criteria for site grading and provide preliminary design information regarding the sta- bility of cut and fill slopes. Recommend an appropriate foundation system for the type of struc- tures and soil conditions anticipated and develop soil engineer- ing design criteria for the recommended foundation design. FINDINGS SITE DESCRIPTION The subject site consists of 18 separate units (which are designated as "villages") in the Calavera Hills Subdivision in Carlsbad, California. Sixteen of the units are contiguous and comprise the eastern portion of Calavera Hills Subdivision; the remaining two units are separated from the other sixteen and constitute the extreme western portion of the subdivi- sion. The morphology of the site is characterized by bold, rugged hills with well-defined drainage channels. Elevations range from approximately 100 feet (MSLD) on the southern portion of the site to approximately 450 - - - .- - - - -. - .- ,- SCS&T 14112 January 6, 1983 Page 5 feet on the north-central portion. Most of the site is in an undeveloped condition. A large water tank is present on the large hill on the north- central portion of the site and a set of northeast trending power lines is present on the eastern portion of the site. Portions of the site have previously been used for agricultural puposes but the former fields are now fallow. Vegetation consists of a moderate to heavy growth of native grasses, shrubs, and chaparral. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located near the boundary between the Foothills Physiographic Province and the Coastal Plains Physiographic Province of San Diego County and is consequently underlain by materials of both igneous and sedimentary origin. Approxi- mately 70% of the site is underlain by the basement complex rocks consist- ing of Jurassic metavolcanic rocks and Cretaceous granitic rocks. Approx- imately 20% of the site is underlain by the sandstones, siltstones, and claystones of the Eocene Santiago Formation. The remaining 10% of the site is underlain by a variety of materials consisting of Cretaceous sediments, Tertiary paleosol, Tertiary volcanic rock, Pleistocene sand- stone, Pleistocene alluvium, Holocene alluvium, and man-made fill. A brief description of the materials encountered, in general decreasing order of age, is presented below. 1) Basement Complex - Jurassic Metavolcanics and Cretaceous Gran- itics (Jmv/Kgr): The oldest rocks exposed at the site are the Jurassic metavolcanic and associated hypabyssal rocks. The metavolcanic rocks are generally andesite or dacite in composi- tion and the associated hypabyssal rocks are their porphyritic equivalents (ie: diorite porphyry to granodiorite porphyry). The fine grained hypabyssal rocks are considered to be about the same age as the metavolcanics and are consequently older than the _- - - .- - - -- - .- - - - - SCS&T 14112 January 6, 1983 other intrusive rocks found at the site. Both the metavolcanics and the associated hypabyssal rocks weather to dark, smooth hills or jagged, angular outcrops with a clayey, rocky topsoil. The metavolcanic and hypabyssal rocks are generally rippable with conventional earth-moving equipment to depths of only a few feet. The other rocks in the basement complex are the granitic rocks of the Cretaceous Southern California Batholith which have intruded the older rocks and are, to a large degree, mixed with them. The granitic rocks at the project site appear to be both tonalitic and granodioritic in composition. The tonalitic rocks are usu- ally dark gray, fine to medium grained rocks whereas the grano- dioritic rocks are usually yellowish brown to grayish brown, medium to coarse grained rocks. The tonalitic rocks appear to be predominant in the southern and west-central portions of the site and the granodioritic rocks appear to be restricted largely to the northern and northeastern portions of the site. The weather- ing and rippability characteristics of the tonalitic rocks appear to be somewhat similar to those of the metavolcanic/hypabyssal rocks. The tonalitic rocks may be rippable to greater depths than the metavolcanic rocks but ripping may be difficut and time consuming. In addition, it should be noted that the material generated from the tonalitic rocks will have the appearance of the metavolcanic rocks rather than that of good quality "decom- posed granite". In contrast to the weathering characteristics of the metavolcanic/hypabyssal rock and the tonalitic rocks, the granodioritic rocks conunonly weather to rounded outcrops or boulders in a matrix of grus ("decomposed granite"). The grano- dioritic rocks are variable in their excavation characteristics but commonly contain areas which are rippable to depths of seve- ral feet or several tens of feet yet include localized areas of boulders or unweathered rock which are not rippable with conven- tional heavy equipment. - _~.. - - - - - _- - - -- - - SCS&T 14112 January 6, 1983 Page 7 The areas underlain by the respective rock types in the basement complex are differentiated on the accompanying geologic map. It should be noted that the different rock types are mixed and the areas on the map only indicate which rock type is dominant. Where the symbol for the metavolcanic rock is listed first (ie: Jmv/Kgr), the area is characterized largely by metavolcanic and hypabyssal rocks with lesser amounts of granitic rock. Conver- sely, where the symbol for the granitic rock is listed first (ie: Kgr/Jmv), the area appears to be underlain predominantly by granitic rock with lesser amounts of metavolcanic and hypabyssal rocks. 2) Lusardi Formation (Kl): The Lusardi Formation is a Cretaceous conglomerate that rests nonconformably on the basement complex and was deposited on a high-relief surface called the "Sub- Lusardi" unconformity. This formation consists largely of gran- itic and metavolcanic boulders in a matrix of coarse grained sandstone and siltstone. The conglomerate is usually poorly sorted and the clasts are conmnonly angular to subrounded. The only area of Lusardi Formation on the subj.ect site proper which is large enough to map as part of this investigation is on the extreme eastern portion of the site. Other areas of Lusardi Formation may be encountered at other portions of the site in subsequent, more-detailed investigations. 3) Tertiary Paleosol (Tp): A zone of ancient paleosol of possible Paleocene/Early Eocene age is present on the basement complex and the Lusardi Formation in a few scattered areas at the project site. This paleosol is the result of the torrid climate and relatively stable geologic conditions that were present in the San Oiego area during the eary Cenozoic era. The resulting ancient soil (paleosol) is lateritic and consists predominantly ersl,TYCDU rA,,Cn~L,,. --,, 1.,,. -CCT,.,m ,..I- -. - - - _-~ - - .- - SCS&T 14112 January 6, 1983 Page 8 of low expansive clays chemically composed of kaolinite and quartz with a small amount of iron oxides which act as a coloring agent. A thin residual cap of ironstone concretious and sili- ceous pebbles is present on much of the paleosol. The thickness of the paleosol was not determined but probably varies from a few feet to a few tens of feet. Only a few areas of paleosol were sufficiently large to map as part of this investigation. It should be noted that other, smaller areas are present at scatter- ed locations throughout the site. 4) Santiago Formation (Es): The Eocene sediments at the project site are represented by the sandstones, siltstones, and clay- stones of the Santiago Formation. The Santiago Formation in the western portion and northeastern portion of the site appears to be characterized largely by the grayish white sandstones and siltstones with lesser amounts of the dark greenish brown clay- stone. The Santiago Formation on the southern portion of the site appears to be predominantly claystone with lesser amounts of sandstone and siltstone. A well-developed, clayey topsoil is present on most of the Santiago Formation. - - ^_ - .~- - 5) Tertiary Volcanic Rock (TV): Cerro de la Calavera is part of a volcanic neck that has intruded the older rocks in the Carlsbad area. The volcanic rock is usually brown to brownish gray and appears to include both dacite and andesite. The weathering characteristics and excavation characteristics of the Tertiary volcanic rock are similar to those of the Jurassic metavolcanic rocks. The only area of Tertiary volcanic rock of sufficient dimension to map for this project was found on the extreme east- ern portion of the site, just west of Cerro de la Calavera. It is possible that future grading operations or more detailed geologic mapping may reveal more of the Tertiary volcanic rock. .- - SCS&T 14112 January 6, 1983 Page 9 6) Quaternary Sandstone (au): A small area of unconsolidated, grayish brown to yellowish brown, fine to medium grained sand- stone of presumed Pleistocene age was encountered at a portion of the northern boundary of the site. This material unconformably overlies the Santiago Formation and may possiby be reworked Santiago Formation material. It is difficult to distinguish the Quaternary sandstone from the Santiago Formation on the basis of their surficial characteristics. This unit was observed in other areas in the general vicinity and may possibly be encountered at other localities on the project site during grading operations. 7) - - Older Quaternary (Pleistocene) Alluvium (Qoal): Older alluvial deposits consisting of grayish brown to yellowish brown and greenish brown, medium dense, silty sands, clayey sands, and sandy silts were encountered at various locations at the project site. These deposits range in thickness from only a few feet to in excess of ten feet. Areas of sufficient lateral extent to map were encountered on the southeastern corner of the site and in the east-central portion of the site. Smaller, un-mapped areas were encountered at other scattered locations. 8) Younger Quaternary (Holocene) Alluvium (Qyal): Younger alluvial deposits consisting of unconsolidated, loose to medium dense deposits of clay, silt, sand, and gravel are present in the modern stream channels. These deposits range in thickness from less than a foot to over ten feet. Due to their ubiguitous occurrence, the younger alluvial deposits are not delineated on the geologic map except in the larger channels. 9) Artificial Fill (Qaf): Several areas of man-made fill which have been obtained from the on-site native materials or other nearby sources were observed. These area are generally limited to small - - - - -. - - - SCS&T 14112 January 6, 1983 Page 10 Earthen dams, minor roads associated with previous agricultural operations, or the remnants of a previous rock-crusing operation on the eastern boundary. Table No. 1 (below) presents some of the pertinent engineering character- istics of the materials encountered at the site. GEOLOGIC CONDITIONS FOR PROPOSED VILLAGES: Table No. II on Page 11 lists the main geologic units encountered at each proposed village and their approximate extent of surface coverage. TABLE I GENER#*Zm ENGINEER1116 CH&iSMTERI*T*cs OF mLOG,C "NlTS “nit Iale awl syb.01 TOPSOi I I ba%mt Of slop E*panl‘“e Rlppablllty Drerslze IUter,a, Stability/Erosion Capressibtlity Potential Rippable NO.i"dl Modemely to Noderate to High Low to High Highly Erodible Older Rll”“i”m-goal U”“aOWd O”~tET”~~y san*rtone-Q” Tertiary “O,U”iC Rock-i” Santiago FO?matiO”-ES jsandrtone & siltstone, sant,ago Fwmation-ES (n”dsto”e, Tertiary Paleorol-Tp LUlardl Formation-K1 Rippable Rlppable Ri,,pable Nomtnai Nominal NOM"dl Harglnally Rippable to Nonrippable Rippable Moderate to High noninal Rlppable Nominal Rlppable to HdPgl"dlly Rlppable Ripfable LW Lou to Moderate LM to "OdWate noderate to "l$l Moderate to High Granitlc ROLXS- Ge”Wally KY Rippdble to (Granodiorlte) t 1s Feet Granttlc RWkI- MdVJi”ally KY (ronalite, Hippable to Nonrlppable Het.YOIC.“lC .4 Harg4”ally Hypabysral Rippable to Rocks-h” Nonri~pable Moderately to Highly Erodible Moderately EVJdlble Highly Erodible Generally Good Generally Good Generally Poor Moderately ErOdlb,e Good &aerate to High Moderate to ll,gil Moderate to High Low to Hodcrate NO”li”dl LOW Low Low HCd”al Nominal NOM”dl Lou to hi gil iml to noderate NO.i”dl LOW to Hoderdte Moderate to /VI sh Ln Lml Nominal Nanlna, SCS&T 14112 January 6, 1983 Page 11 TABLE II Geologic Percent of Geologic Percent of Village Unit Surface Coverage Village Unit Surface Coverage - - - - El Kgr/Jmv Jmv/Kgr - E2 JmvfKgr _- H Es Qyal - - .- .- I ES 95% Qyal 5% K Jmv/Kgr Kgr/Jmv 60% 40% P2 Jmv/Kgr 50% Kgr/Jmv 50% Q Jmv/Kgr Kgr/Jmv Qyal Rl Kgr/Jmv TP ES Qu Qyal R2 ES 60% s Jmv/Kgr 40% 100% T 90% U 10% 50% 45% 5% 25% 5% 55% 10% 5% 100% Y Zl 22 Kgr/Jmv TP Qoal 20% 30% 5% 45% Jmvfkgr Kgr/Jmv TP 55% 40% 5% Jmv/Kgr Kgr/Jmv Kl TV Qaf 35% 35% 15% 5% 10% Jmv/Kgr Kgr/Jmv 90% 10% KmvjKgr Kgr/Jmv Kl 90% 5% 5% Jmv/Kgr Kl Qoal Qyal 75% 5% 15% 5% Jmv/Kgr 100% Jmv/Kgr 65% Kgr/Jmv 30% Qoal 5% Jmv/Kgr Kgr/Jmv Es TP 40% 35% 20% 5% - SCS&T 14112 January 6, 1983 - .~ - - .- - .- .- - .- .- - TECTONIC SETTING: A few small, apparently inactive faults have been mapped previously at the site. No evidence of faulting was noted in our exploratory trenches for this investigation but it is possible that future grading operations at the site may reveal some of these faults. Due to their status of activity and geometry, these small faults should be of only minor consequence to the project. It should also be noted that several prominent fractures and joints which are probably related, at least in part, to the strong tectonic forces that dominate the Southern California region are present at the site. These features are usually near-vertical and strike in both a general north- westerly direction (subparallel to the regional structural trend) and in a general northeasterly direction (subperpendicular to the regional struc- tural trend). All cut slopes should be inspected by a qualified geologist to assess the presence of adverse jointing conditions in the final slopes. In addition, it should be recognized that much of Southern California is characterized by major, active fault zones that could possibly affect the subject site. The nearest of these is the Elsinore Fault Zone, located approximately 20 miles to the northeast. It should also be noted that the possible extension of the Rose Canyon Fault Zone is located approximately 8 miles west of the site. The Rose Canyon Fault Zone is currently classi- fied as only potentially active, rather than active, according to the criteria of the California Division of Mines and Geology. Due to the current classification of the Rose Canyon Fault Zone, it is our opinion that it should not be used as the design earthquake source for conven- tional residential structures. GEOLOGIC HAZARDS: The project site is located in an area which is rela- tively free of significant geologic hazards. The most likely geologic hazard to affect the site is groundshaking as a result of movement along one of the major, active fault zones mentioned previously. Based on a E”llTYSDN Cn,,l”OM,a =“,I AN” TF9TING~ INC - - - - - - - - -. - - SCS&T 14112 January 6, 1983 Page 13 maximum probable earthquake of 7.3 magnitude along the Elsinore Fault Zone, maximum ground acceleration at the site could be as high as 0.25 g. Conventional commercial and residential structures, four stories or less in height, that are constructed in accordance with the minimum standards of the Uniform Building Code should be able to withstand accelerations of this level without experiencing structural distress. Another potential geologic hazard which may affect the site is the possi- bility of minor slope stability problems associated with either adverse jointing conditions in the various rock units or low strength parameters of the claystones in the Santiago Formation. The effects of this poten- tial hazard can be satisfactorily mitigated through the use of sound geotechnical practices and proper slope maintenance techniques. Other potential geologic hazards such as tsunamis, seiches, liquefaction, or seismic-induced settlement should be considered to be negligible or nonexistent. 1H)IVIDUAL AREA CHARACTERISTICS: For easy identification of the ripp- ability characteristic within the individual villages, the following table summarizes the soil/rock conditions anticipated. SEISMIC SURVEY AND RIPPABILITY CHARACTERISTICS GENERAL: The results of our seismic survey and exploratory trenches indicate that blasting may be required to obtain proposed road cuts. In addition, isolated boulders are anticipated within road cut areas that may require special handling during grading operations. A sumnary of each seismic traverse is presented in the table below and on Plates Number 63 and 64. Our interpretation is based on the rippability characteristics of granitic and metavolcanic rock as described in pages 22 through 25. - - - - - . - . _ _ _ _, . ^ _ . ., _ - - - - . ^ L. ^ -- - - -. - - - - - SCS&T 14112 January 6, 1983 Page 14 TABLE III The second letter of each seismic traverse number identifies the individ- ual village where the traverse was performed. Seismic Traverse No. SE&l Area: E2 Geologic Unit: Metavolcanic and Associated Hypabyssal Rock Interpretation: O-3' Rippable 3'-15' Marginally Rippable + 15' Nonrippable Seismic Traverse No. SE2-2 Area: E2 Geologic Unit: Metavolcanic and Associated Hypabyssal Rock, Fill Interpretation: O-5' Rippable 5'-9' Marginally Rippable 9’-16” Marginally to Nonrippable + 16' Nonrippable Seismic Travers No. Sk-3 Area: K Geologic Unit: Granitic Rock (Tonalite) Interpretation: O-16' Rippable + 16' Nonrippable Seismic Traverse No. SK-4 Area: K Geologic Unit: Metavolcanic and Associated Hypabyssal Rock Interpretation: O-5' Rippable with isolated boulders 5'-9' Marginally Rippable + 9' Nonrippable IrBIITYCDN cA,,Cna&J,a c&n,, &*l” 7CE7,..nc2 IhIP - -. - - -~ - -, - - - - - - - - SCS&T 14112 January 6, 1983 TABLE III (continued) Seismic Traverse No. SK-5 Area: K Geologic Unit: Granitic Rock (Tonalite) Interpretation: O-8' Rippable + 8' Marginally to Nonrippable Related Trench: TK-3 Seismic Traverse No. SP-6 Area: P Geologic Unit: Granitic Rock (Grandiorite) Interpretation: O-15’ Rippable + 15' Nonrippable Related Trench: TP-3 Seismic Traverse No. SQ-7 Area: Q Geologic Unit: Granitic Rock (Granodiorite) Interpretation: O-19’ Rippable f 19' Nonrippable Seismic Traverse No. SQ-8 Area: Q Geologic Unit: Granitic Rock (Granodiorite) Interpretation: O-14' Rippable + 14' Nonrippable Seismic Traverse No. SR-9 Area: R-l Geologic Unit: Granitic Rock (Granodiorite) Interpretation: O-19' Rippable 19’-30’ Rippable to Marginally Rippable + 30' Nonrippable Page 15 -. - _. - - .- - SCS&T 14112 January 6, 1983 Page 16 TABLE III (continued) Seismic Traverse No. SV-10 Area: v Geologic Unit: Granitic Rock (Granodiorite) Interpretation: O-17' Rippable + 17' Nonrippable Seismic Traverse No. SW-11 Area: W Geologic Unit: Metavolcanic and Associated Hypabyssal Rock Interpretation: O-5' Rippable + 5' Nonrippable Seismic Traverse No. SW-12 Area: W Geologic Unit: Metavolcanic and Associated Hypabyssal Rock Interpretation: O-4' Rippable 4'-21' Rippable to Marginally Rippable f 21' Nonrippable Seismic Traverse No. SW-13 Area: W Geologic Unit: Granitic Rock (Tonalite) Interpretation: O-15' Rippable t 15' Nonrippable Seismic Traverse No. SW-14 Area: W Geologic Unit: Granitic Rock (Tonalite) Interpretation: O-14' Rippable 14'-21' Marginally to Nonrippable + 21' Nonrippable c”IITyrm.I -.. *C-“s*la c-II ..I^ - r _ - # .* _ , .I c - SE&T 14112 January 6, 1983 Page 17 TABLE III (continued) - .- .- - -. .- - Seismic Traverse No. SX-15 Area: X Geologic Unit: Alluvium and Metavolcanic/Hypabyssal Rock Interpretation: O-11' Rippable + 11' Nonrippable Related Trench: TX-l Seismic Traverse No. Z-16 Area: z-1 Geologic Unit: Granitic Rock (Tonalite) Interpretation: O-16' Rippable 16'-19' Marginally to Nonrippable f 19' Nonrippable Seismic Traverse No. SZ2-17 Area: 2-2 Geologic Unit: Metavolcanic and Associated Hypabyssal Rock and Granitic Rock Interpretation: Metavolcanic and Associated Hypabyssal Rock O-4' Rippable t4' Nonrippable Granitic Rock (Tonalite) O-19’ Rippable + 19’ Nonrippable e 0 UT Y Fe N c P L , cm D I.j, d 9 n,, & ,., n _ c c -, ., _ , . . - - - - -- - - - _- - - - - SCS&T 14112 January 6, 1983 Page 18 In general, our seismic survey indicated that areas underlain by granitic rock present rippable material to an average depth of 162 feet, with nonrippable material below this depth. In areas underlain by metavolcanic and associated hypabyssal rock, nonrippable material appears closer to the surface at a minimum depth of 4+ feet. In addition, a variable zone of marginally rippable rock usually exists between the rippable and nonrip- pable rock. The generation of fine material during blasting and mining operations is essential due to the characteristics of the on-site rock material. There- fore, "pre-shooting" of nonrippable material before removing the overlying soils and rippable rock is suggested. This procedure often helps to generate more fine material and to facilitate the mixing of soil and rock to be used as fill. TABLE IV Area E-l: This area is underlain by both metavolcanic and grani- tic (tonalitic) rock. Metavolcanic rock is exposed on the southwestern portion of the lot. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Area E-2: Area E2 is underlain predominantly by metavolcanic rock. This material may be nonrippable from a depth of 4+ feet. It also usually presents a variable zone of marginally rippable rock overlying the nonrippable rock. SOUTYFDhl r~,,CnoN,a Fin,, II.ln TCET,L,c led.- - - - .- - - - .- - - - SCS&T 14112 January 6, 1983 Page 19 TABLE IV (continued) Area K-l: This lot is almost evenly divided between granitic and metavolcanic rock with the [majority of the granitic rock underlying its central section. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Area P: Area P is approximately equally divided between meta- volcanic and granitic rock. Most of the metavolcanic rock within Area P appears to be concentrated at the higher elevations of the lot. Granitic rock underlies the western and northern sections of Area P as well as its southeastern corner. It is anticipated that grani- tic rock will be rippable to depths ranging from approx- imately 10 feet to several tens of feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Area Q: Area Q also appears evenly proportioned between meta- volcanic and granitic rock. The metavolcanic rock comprises most of the hillside. It is anticipated that granitic rock will be rippable to depths ranging from 10 feet to several tens of feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usu- ally presents a zone of marginally rippable rock over- lying the nonrippable material. SOUTHERN CALIFDRNIA SOIL AND T E s T I N G. I N c. SCS&T 14112 January 6, 1983 Page 20 TABLE IV (continued) - - - - - - .- - - - - _- -, - - - Area R-l: Granitic rock is present within the southwestern corner of this lot, the rest is underlain by sediments. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Area S: Most of Area S is underlain by older alluvium extending to a maximum depth of at least 12+ feet. The alluvial deposits overlie granitic rock. The majority of the remaining surface rock is also granitic with isolated metavolcanic rock along the southern and eastern edges of the lot. It is anticipated that granitic rock will be rippable to a depth of approximately 10 feet to several tens of feet. Metavolcanic rock may be nonrip- pable from a depth of 4+ feet. It also usually pre- sents a zone of marginally rippable rock overlying the nonrippable material. Area T: Most of Area T is underlain by metavolcanic rock. However numerous small, isolated, granitic rock areas exist throughout this lot. It is anticipated that granitic rock will be rippable to a depth of approxi- mately 10 to 15 feet. Metavolcanic rock may be nonrip- pable from a depth of 4+ feet. It also usually pre- sents a zone of marginally rippable rock overlying the nonrippable material. Area U: The higher section of Area U (above elevation 180+ feet MSL) is underlain by granitic and metavolcanic rock. Granitic rock comprises the south facing canyon hill- side. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. SOUTHERN CALIFORNIA BOIL AND TESTING. INC. - - - ..~_ - - - SCS&T 14112 January 6, 1983 Page 21 TABLE IV (continued) Area V: Area V is primarily underlain by metavolcanic rock, sprinkled with small isolated zones of granitic rock. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavol- canic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Area W: Area W is primarily underlain by metavolcanic rock, sprinkled with small isolated zones of granitic rock. It is anticipated that granitic rock will be rippable to a depth of aproximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Area X: Rock within Area X consists of metavolcanic rock com- prising the northern portion of the lot. In general the rock is encountered above elevation 190+ feet MSL. Area Y: Area Y is underlain by metavolcanic rock. This mate- rial may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable rock. Area Z-l: Metavolcanic rock comprises the northwestern two-thirds of this lot, the rest of Area Z-l is primarily under- lain by granitic rock. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4t feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. SOUTHERN CAL#FORNIA SOIL AND TESTING. INI? - .- - -. - - - SCS&T 14112 January 6, 1983 Page 22 TABLE IV (continued) Area Z-2: The hillside section of this lot is underlain by meta- volcanic rock (above elevation 1002 feet MSL) and granitic rock. It is anticipated that granitic rock will be rippable to a depth of approximately 10 to 15 feet. Metavolcanic rock may be nonrippable from a depth of 4+ feet. It also usually presents a zone of marginally rippable rock overlying the nonrippable material. Areas H & I: These areas are not underlain by rock deposits and are easily rippable to anticipated cut depths. RIPPABILITY CHARACTERISTIC OF GRANODIDRITIC ROCK Rippable Condition (0 -4,500 Ft./Set.): This velocity range indicates rippable materials which may consist of decomposed granitics possessing random hardrock floaters. These materials will break down into slightly silty, well graded sand, whereas the floaters will require disposal in an area of nonstructural fill. Some areas containing numerous hardrock floaters may present utility trench problems. Further, large floaters exposed at or near finish grade may present additional problems of removal and disposal. Materials within the velocity range of from 3,500 to 4,000 fps are ripp- able with difficulty by backhoes and other light trenching equipment. Marginally Rippable Condition (4,500 - 5,500 Ft.Sec.): This range is rippable with effort by a O-9 in only slightly weathered granitics. This velocity range may also include numerous floaters with the possibility of extensive areas of fractured granitics. Excavations may produce material ErlllTYCO*I PAIIC”DUIA En,, hI.8” T5GTl?.l,Y ,NC SCS&T 14112 January 6, 1983 Page 23 - - - - - - - - - - - - that will partially break down into a coarse, slightly silty to clean sand, but containing a high percentage of + l/4" material. Less fractured or weathered materials may be found in this velocity range that would require blasting to facilitate removal. Materials within this velocity range are beyond the capability of backhoes and lighter trenching equipment. Difficulty of excavation would also be realized by gradalls and other heavy trenching equipment. Nonrippable Condition (5,500 Ft./Set. & Greater): This velocity range includes nonrippable material consisting primarily of fractured granitics at lower velocities with increasing hardness of fractured granitics at lower velocities with increasing hardness at higher velocities. In its natural state, it is not desirable for building pad subgrade. Blasting will produce oversize material requiring disposal in areas of nonstruc- tural fill. This upper limit has been based on Rippability Chart No. 3 utilized for this report. However, as noted in the two Caterpillar charts (Nos. 1 and 2), this upper limit of rippability may sometimes be increased to 7,000 to 8,000 fps material using the O-9 mounted #9 Series 0 Ripper. RIPPABILITY CHARACTERISTICS OF METAVOLCANICS AND ASSOCIATED HYPABYSSAL ROCKS AND TONALITIC ROCKS Rippable Condition (o-4.500 Ft./Set.): This velocity range indicates rippable materials which may vary from decomposed metavolcanics at lower velocities to only slightly decomposed, fractured rock at the higher velocities. Although rippable, materials may be produced by excavation that will not be useable in structural fills due to a lack of fines. Experience has shown that material within the range of 4,000 to 4,500 fps most often consists of severely to moderately fractured rock with little or no fines and sizeable quantities of t l/4" material. c .-. ** - - c ” _, - _ . L - - _. _ - -. * . ., - - c = - I LI ,? I al P - - - - - - - - - SCS&T 14112 January 6, 1983 Page 24 For velocities between 3,500 to 4,500 fps, rippability wit11 be difficult for backhoes and light trenching equipment. Marginally Rippable Condition (4,500 - 5,500 Ft./Set.): Excavations in this velocity range would be extremely time consuming and would produce fractured rock with little or no fines. The higher velocities could require blasting. Trenching equipment would not function. Nonrippable Condition (5,500 Ft./Set. & Greater): This velocity range may include moderately to slightly fractured rock which would require blasting for removal. Material produced would consist of a high percentage of oversize and angular rock. Rippability of metavolcanics could be accomplished for higher velocities using the Caterpillar O-9 with the #9 0 Series Ripper. Due to the frac- tured nature of the metavolcanics, ripping might be accomplished in as high as 8,100 fps material. RIPPABILITY CHARACTERISTICS Rippability Charts: L/e are including a rippability chart which applies to the site conditions. The chart is a modification of charts by the Cater- pillar Company and an article in "Road and Streets", September, 1967, which we feel approximately defines rippability with the D-9 using a conventional #9 Single Shank Ripper. D9 Cat - #9 Single Shank Ripper (Conventional) Rippable 0 - 4,500 fps Marginally Rippable 4,500 - 5,500 fps Nonrippable 5,500 + fps - - - - - - - SCS&T 14112 January 6, 1983 Page 25 SEISMIC TRAVERSE LIMITATIONS The results of the seismic survey for this investigation reflect rip- pability conditions only for the areas of the traverses. However, the conditions of the various soil-rock units appear to be similar for the remainder of the site and may be assumed to possess similar characteris- tics. Our reporting is presently limited in that refraction seismic surveys do not allow for predicting a percentage of expectable oversize or hardrock floaters. Subsurface variations in the degree of weathered rock to frac- tured rock are not accurately predictable, but have been indicated where thought to possibly exist. The seismic refraction method requires that materials become increasingly dense with depth. In areas where denser, higher velocity materials are underlain by lower velocity materials, the lower velocity materials would not be indicated by our survey. All of the velocities used as upper limits from Rippability Chart are subject to fluctuation depending upon such local variations in rock condi- tions as: a) Fractures, Faults and Planes of Weakness of Any Kind b) Weathering and Degree of Decomposition cl Brittleness and Crystalline Nature d) Grain Size Further, the range of rippability using Caterpillar equipment may be increased using different equipment. However, it should be noted that ripping of higher velocity materials may become totally dependent on the time available and the economics of the project. Ripping of higher velo- city materials can be achieved but it may become economically infeasible. snUTl4ERN CALL1l3ONNIA SOIL AND TESTINC1. INC SCS&T 14112 January 6, 1983 Page 26 RECOMMENDATIONS AND CONCLUSIONS - .- - - - - - - ,- - .- GENERAL : No geotechnical conditions were encountered which would preclude the development of the site provided the recommendations presented herein are followed. Since no special details are presently known regarding the development of the individual villages, many of the following recoaunenda- tions are general and further geotechnical work may be required once the specific development plans are defined. The main condition affecting site development is the presence of granitic and metavolcanic rock underlying vast portions of the site. This material will require blasting to achieve proposed final grades and will require special handling during grading. Several areas are underlain primarily by metavolcanic and associated hypabyssal rock. It is anticipated that the material generated from the blasting of these materials may contain relatively low amounts of fine soils. Since rock fills require a percentage of fine soil in excess of that anticipated from the mining of the site, importing of fine material or exporting excess rock may be necessary if large cuts are proposed in metavolcanic rock. SITE PREPARATION GENERAL : The majority of the site is covered by a thin layer of topsoil deposits ranging in average thickness from l.O+ foot to 2.0 feet in areas underlain by rock or Santiago Formation deposits, respectively. Due to their porous condition, the topsoils are considered unsuitable for the support of settlement sensitive improvements and will require remedial grading. Alluvial deposits at the site were classified as older and younger alluvium. The older alluvium is overlain by topsoils which should be treated as described above. The older alluvium should provide compe- SOUTHERN C*LLIFOmNoP s.O,L AND TESTING. INC .~~~ - -. - .- -- - - . . - .., - _. SCS&T 14112 January 6, 1983 Page 27 tent foundation support. The upper zone younger alluvium located at the bottom of canyons is generally loose and will require remedial grading as described herein. Existing fill deposits are also unsuitable for the support of settlement sensitive improvements. Site preparation should begin with the removal of all deleterious matter and vegetation. Younger alluvial deposits underlying areas to receive fill and/or structural loads should be excavated to firm natural gound. It is estimated that the maximum depth of removal for road construction will be 5+ feet. This depth may vary in different areas of the site depending upon proposed improvements. Topsoils and fill deposits should be removed in their entirety. Firm natural ground is defined as soil having an in-place density of at least 85% of the maximum dry density as determined in accordance with ASTM test procedure D-1557-78, Method A. The removal of unsuitable soils should extend a minimum horizontal distance of five feet beyond the perim- eter of the improvement or to the property line whichever is more. The exposed natural ground should then be scarified to a depth of 12 inches, moisture conditioned and recompacted to at least 90% of maximum dry den- sity at a minimum moisture content at or slightly above optimum. The overexcavated soils as well as imported fill should then be placed in compacted layers until desired elevations are reached. SUBDRAINS: It is recommended that subdrains be placed along the bottom of canyons to receive fill deposits. The subdrains should be extended from discharge to a point where the overlying fill is at least 10 feet deep. Subdrain details are provided in Plate Number 66. The last 10 feet of subdrain should consist of solid pipe. ROCK DISPOSAL: It is anticipated that large amounts of shot-rock will be generated during grading operations. In addition, isolated boulders are SOUTHERN CALIFORNIA SOIL ANO T E 5 T I l-4 0. I F-4 c. - _- - - - -. - . - ,- .- - .- SCS&T 14112 January 6, 1983 Page 28 expected to occur within the rippable and marginally rippable rock. This oversized material should be placed in accordance with the grading speci- fications provided in Appendix B and the recommendations of Plate Number 67. SELECT GRADING: It is recommended that expansive soils at finish grade elevations be replaced with a 2.5 foot cap of properly compacted, non- detrimentally expansive fill. Areas of expansive soils are further de- fined in the "Expansive Characteristics" section of this report. As an alternate, specially designed foundation and on-grade-slabs may be used when expansive soils will occur within 2.5 feet of finish grade. Additional select grading may be required in order to provide enough fines for rock fills. A primary source within the site are Villages R-l, R-2, I and H which are underlain by sediments. In addition cuts less than 15+ feet deep in areas underlain by granodioritic rock (Villages F-l, P, Q, R-l, S, T and U) should generate select material. If the villages are graded separately, off-site select import soil may be required for areas E-2, K, V, W, X, Y, Z-1 and Z-2 which are primarily underlain by metavol- canic and tonalitic rock. UNUERCUTTING: In order to facilitate foundation excavations within cut areas underlain by hardrock, it is suggested that said areas be undercut to a depth of 12 inches below the bottom of the footing and be replaced with compacted nonexpansive soil. This procedure may also be advantageous for the construction of utility trenches in building pad areas. Since the total areas required should not be large, utility line "alleys" may be created by concentrating the lines in narrow undercut zones. This proce- dure is probably too costly for utility lines in streets. Therefore, blasting should be anticipated for trenches in areas underlain by hard- rock. -^..-..--L. -_. .--- . __., ._,- ----...- *.a- - - .- -- - SCS&T 14112 January 6, 1983 Page 29 EARTHWORK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Recommended Grading Specifications and Special Provisions. All special site preparation recommendations presented in the sections above will supersede those in the standard Recommended Grading Specifications. All embankmensts, struc- tural fill and fill should be compacted to a minimum of 90%. Utility trench backfill within 5 feet of the proposed structures and beneath asphalt pavements should be compacted to a minimum of 90% of its maximum dry density. The maximum dry density of each soil type should be deter- mined in accordance with A.S.T.M. test Method 1557-78, Method A or C. SLOPE STABILITY SLOPES FOR ACCESS ROADS: It is our understanding that 2:l (horizontal to vertical) cut and fill slopes, extending to a height of 30 + feet and 65 + feet, respectively are anticipated for the construction of the proposed access roads. It is further our understanding that said slopes will be constructed in areas underlain primarily by metavolcanic and granitic rock and that only native material will be utilized. It is our opinion that the proposed cut and fill slopes should possess a factor of safety in excess of 1.5 with respect to deep-seated failure. This was determined utilizing Janbu's simplified slopes stability method (see Plate No. 68) and average shear strength parameters for fill soils of $ = 35" and c = 200 psf. These values are consistent with our findings and our experience with similar soil conditions and, are considered to be conservative. ADDITIONAL SLOPES: At the present time no information is available regard- ing other proposed slopes throughout the site. Plate Number 68 presents maximum cut and fill slope heights for slopes constructed in areas under- lain by Santiago Formation deposits. Weak strata were encountered within - - - SCS&T 14112 January 6, 1983 Page 30 - _- - - - this formation during the investigation of the original site, in areas outside the limits of this study. In addition, minor lenses (less than one foot thick) were found in area R-l. Our investigation encountered random, relatively thin lenses of potentially weak siltstones and clay- stones in areas I and H. It is our opinion that this material should not affect the stability of cut slopes within said areas. However, additional studies may be required if large cuts are proposed there. Large cuts in said areas may necessitate the buttressing of cut slopes. FOUNDATIONS GENERAL : Conventional spread footings founded at least 12 inches below lowest adjacent finished grade and having a minimum width of 12 inches are recommended for the support of single story structures. This minimum depth should be increased to 18 and 24 inches for two and three to four story structures respectively. The minimum width should also be increased to 15 and 18 inches for two and three or four story buildings, respec- tively. Such footings may be designed for an allowable soil bearing pressure of 2500 psf. This bearing pressure may be increased by one-third when considering wind and/or seismic loads. It is further recomnended that a minimum setback of eight feet be observed for structures located near the top of slopes. The above recommendations assume a nondetrimen- tally expansive soil condition within 2.5 feet of finish grade. The recommendations provided in this section are general and may be re- vised for specific site development plan once these are available. REINFORCING: It is recommended that minimum reinforcement consist of two continuous No. 4 reinforcing bars, one located near the top of the footing and one near the bottom. It is further recomnended that for footings spanning daylight lines where the fill section exceeds four feet in thick- ness, the minimum reinforcement be increased to four No. 4 bars (two - - -. - SCS&T 14112 January 6, 1983 Page 31 - - - - - - - - - - located at the top and two at the bottom) extending at least 20 feet, both ways, from the daylight line. This reinforcement is based on soil charac- teristics and is not intended to be in lieu of reinforcement necessary to Satisfy structural considerations. CONCRETE SLABS-ON-GRADE: Concrete slabs-on-grade should have a minimum thickness of four inches and be reinforced with a 6"x6"-lo/10 welded wire mesh throughout. Where moisture sensitive floor coverings are planned, the slab should be underlain by a visqueen moisture barrier. A two-inch thick layer of sand should be provided above the visqueen to allow proper concrete curing. SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential settlements for structures may be considered to be within tolerable limts provided the recommendations presented in this report are followed. EXPANSIVE CHARACTERISTICS: Soils encountered throughout our investigation range from nondetrimentally to highly expansive. The foundation recom- mendations provided in this report are based on a nondetrimentally expan- sive soil condition. If expansive soils are encountered within 2.5 feet of finished grade, deeper footings and/or additional reinforcing may be required. In general, moderately to highly expansive soils were encountered in the following areas: a) Thin zones of nearsurface expansive soils (average thickness 2.0+ feet) capping areas underlain by metavolcanic and granitic rock. b) Some alluvial deposits were found to be expansive, primarily in area Z and some of the alluvium in area R-l. Cnll7YCm.I C*lIC-“.*,& cr.,, *..,n TCCTI*Irz ,hlr .- - ..- - .- SCS&T 14112 January 6, 1983 Page 32 cl Random lenses of expansive claystones and siltstones within the Santiago formation deposits. These lenses were encountered in areas H and I extending to a maximum thickness of 4.0+ feet. However, this condition is typical of Santiago Formation deposits and may be also encountered in Area R-l. d) Mudstones of Santiago Formation in Area 22. e) Expansive topsoils and nearsurface zones of expansive weathered material (average thickness 2.0 feet) were encountered in areas underlain by Santiago Formation Deposits. f) Portions of the Quaternary sandstone in area R-l were found to be moderately expansive. - - It is recommended that areas with expansive soils within 2.5 feet of finished grade be undercut and capped with nondetrimentally expansive compacted fill and that in fill areas, no expansive soil be placed within 2.5 feet of finish grade. EARTH RETAINING STRUCTURES ULTIMATE PASSIVE PRESSURE: The passive pressure for prevailing soil conditions may be considered to be 300 pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.43 for the resistance to lateral movement. When combining frictional and passive resistance, the latter should be reduced by one-third. ULTIMATE ACTIVE PRESSURE: The ultimate active soil pressure for the design of earth retaining structures with level backfills may be assumed to be equivalent to the pressure of a fluid weighing 35 pounds per cubic SOUTHERN CALIFORNIA 50,L AND TESTING. INC. - - _- - .- - - - SCS&T 14112 January 6, 1983 Page 33 foot for walls free to yield at the top (unrestrained walls). For earth retaining structures that are fixed at the top (restrained walls), an ultimate equivalent fluid pressure of 45 pounds per cubic foot may be used for a design parameter. These pressures do not consider any surcharge loading (other than the sloping backfill). If any surcharge loadings are anticipated this office should be contacted for the necessary change in soil pressure. All earth retaining structures should have adequate weep holes or a subdrain system to prevent the buildup of hydrostatic pressure behind the wall. BACKFILL: All backfill soils should be compacted to at least 90% relative compaction. Expansive or clayey soils should not be used for backfill material within a distance of 5 feet from the back of the wall. The retaining structure should not be backfilled until the materials in the wall have reached an adequate strength. FACTOR OF SAFETY: The above values do not include a factor of safety. Appropriate factors of safety should be incorporated into the design of all earth retaining structures to reduce the possibility of overturning and sliding. LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. The soil engineer and engineer- ing geologist should review and verify the compliance of the final grading plan with this report and with Chapter 70 of the Uniform Building Code. It is recommended that the soil and foundation engineer be retained to provide continuous soil engineering services during the earthwork opera- - - C”llTYFDM ,TA,,C”abJ,n -“,I AN” TFFT,Nm~ INIZ - - SCS&T 14112 January 6, 1983 Page 34 . - .- - - - - - - - - tions. This is to observe compliance with the design concepts, specifica- tions or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. UNIFORMITY OF CONOITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsur- face soil conditions encountered at the subsurface exploration locations and the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undis- closed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the soils engineer so that he may make modifi- cations if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that it may be determined if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the State-of-the-Art and/or BmUTYcnhl c., ,Cnal.l,n ~-“,I *N” TSCT,l.lC IUP - - -- .- - - -- - - - - - SCS&T 14112 January 6, 1983 Page 35 Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession cur- rently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encoun- tered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations are based soley on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports of findings. CLIENT'S RESPONSIBILITY It is the responsibility of Calavera Hills Company or their representa- tives to ensure that the information and recommendations contained herein are brought to the attention of the engineer and architect for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to ensure that the contractor and his subcontractors carry out such recommendations during construction. !sOLlTYE~LI c*,,ccloM,A can,, ,%&In TSETIr.i#? ,bJc - - - - - - - - - SCS&T 14112 January 6, 1983 Page 36 FIELD EXPLORATIONS Fifty-three subsurface explorations were made at the locations indicated on the attached Plate Number 1 on December 15, 16 and 21, 1982. These explorations consisted of trenches excavated utilizing a rubber-tired backhoe equipped with a 24-inch bucket. In addition, seventeen seismic traverse lines were performed. The field work was conducted under the observation of our engineering geology personnel. The explorations were carefully logged when made. These logs are present- ed on the following Plate Numbers 3 through 55. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart on Plate 2. In addition, a verbal text- ural description, the wet color, the apparent moisture, and the density or consistency are given on the logs. Soil densities for granular soils was given as either very loose, loose, medium dense, dense, or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. Disturbed and undisturbed samples of typical and representative soils were obtained and returned to the laboratory for testing. Fourteen seismic traverses and nine exploratory borings were performed in conjunction with our pre-preliminary soil investigation of June 7, 1973. The results of 11 traverses and 2 borings pertaining to our present study are presented in Appendix A. The logs of 18 bulldozer trenches performed in April, 1981 by Earth Research Associates, Inc. are also included in Appendix A. .- -- - - - .- SCS&T 14112 January 6, 1983 Page 37 LABORATORY TESTING Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (A.S.T.M.) test methods or suggested procedures. A brief description of the tests performed are presented below: a) MOISTURE-DENSITY: Field moisture content and dry density were determined for representative undisturbed sample obtained. This information was an aid to classification and permitted recogni- tion of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the field moisture content is determined as a percentage of the soil's dry weight. The results are summarized in the trench logs. b) CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System. cl GRAIN SIZE DISTRIBUTION: The grain size distribution was deter- mined for representative samples in accordance with ASTM Standard Test D-422. The results of this test are presented on Plate Numbers 59 through 62. d) DIRECT SHEAR TESTS: Direct shear tests were performed to deter- mine the failure envelope based on yield shear strength. The shear box was designed to accomodate a sample having a diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and at saturated moisture content. The shear stress was applied at a constant rate of strain of approximately 0.05 inches per minute. The results of these tests are presented on attached Plate Number 57. SDUTHERN CALLFFORNIP sn,L AND TESTIbID. 1 N c - -. - .- .- - - - SCS&T e 14 1 f) ,112 COMPACTION TEST: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with A.S.T.M. Standard Test D-1557-78, Method A. The Results of these tests are presented on the attached Plate Number 56. EXPANSION TEST: The expansive potential of clayey soils was determined in accordance with the following test procedures and the results of these tests appear on Plate Number 58. Allow the trimmed, undisturbed or remolded sample to air dry to a constant moisture content, at a temperature of 100 degrees F. Place the dried sample in the consolidometer and allow to compress under a load of 150 psf. Allow moisture to contact the sample and measure its expansion from an air dried to saturated condition. 9) CONSOLIDATION TEST: A consolidation test was performed on select- ed "undisturbed" sample. The consolidation apparatus was design- ed to accomodate a 1 inch high by 2.375 inch or 2.500 inch diame- ter soil sample laterally confined by a brass ring. Porous stones were placed in contact with the top and bottom of the sample to permit the addition or release of pore fluid during testing. A load of 5.16 ksf was applied to the sample, and the resulting deformations were recorded. The percent consolidation is reported as the ratio of the amount of vertical compression to the original one-inch sample height. The test sample was inun- dated at some point in the test cycle to determine its behaviour under the anticipated footing load as soil moisture increases. The results of this test are presented on Plate Number 63. January 6, 1983 Page 38 SOUTHERN CAL,FORN,A ea,L Ahl” TFCTIP.d.7 I..,-