Loading...
HomeMy WebLinkAboutCT 74-21; Carlsbad Oaks; Soils Report; 1981-11-12." Project No. 51218G-SI01 - SOIL AND GEOLOGICAL INVESTIGATION FOR THE PROPOSED CARLSBAD OAKS CARLSBAD, CALIFORNIA (CT 74-21) for Techbilt Construction Santa Fe Company P.O. Box 80036 San Diego, California cow. 92138 L- L I 3467 Kurt2 Street San Dlego Calllor68a 921 10 714-224-2911 V!aoadward=Clyde Consultants November 12, 1981 Project No. 51218G-SI01 Techbilt Construction COD. - Santa Fe Company P.O. Box 80036 San Diego, California 92138 Attention: Mr. Paul Tchang SOIL AND GEOLOGICAL INVESTIGATION FOR THE PROPOSED CARLSBAD OAKS CARLSBAD, CALIFORNIA (CT 74-21) Gentlemen: We are pleased to provide the accompanying report, which pre- sents the results of our soil and geological investigation for the subject project. , This study was performed in accordance with our proposal dated August 6, 1981 and your authorization of August 13, 1981. The report presents our conclusions and recommendations per- taining to the project, as well as the results of our field explorations and laboratory tests. Our engineer and geologist assigned to this project are Messrs. Peter Dilks and Jeffrey Brown, respectively. If you have any questions or if we can be of further service, please give us a call. Very truly yours, WOODWARD-CLYDE CONSULTANTS R.E. 18352 C.EIG. 1033 SFG/DS/PD/JB/pjk (2 ) Santa Fe Company (4) Rick Engineering Attention: Barry Bender San Marcos Office Consult~ng Engineers. Geolog~sls ana Enwonmenla* ScienliSlS Ofllces In Other Princlpal Cllles I - Project No. 51218G-SI01 Woodward.clyde Consultants TABLE OF CONTENTS Page - PURPOSE AND SCOPE OF INVESTIGATION - DESCRIPTION OF THE PROJECT FIELD AND LABORATORY INVESTIGATION Geologic Setting Topography and Surface Conditions Subsurface Conditions Structure Faulting and Seismicity Landslides Ground Water DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS Geologic Hazards Ground Water Slopes Soil and Excavation Characteristics Grading Foundations Settlements Pavements OFFSITE CONSIDERATIONS I. RISK AND OTHER CONSIDERATIONS 1 2 8 8 10 11 12 12 14 15 15 16 18 i Project No. 51218G-SI01 Table of Contents (Continued) FIGURES 1. Site Plan 2. Geologic Cross Sections 3. Settlement Curve 4. Wedge Failure Configuration Page APPENDIXES A. Field Investigation Figures A-1. Key to Logs A-2 through A-41. Logs of Test Borings B. Laboratory Tests Figures B-1 and B-2. Grain Size Distribution Curves B-3 and B-4. Results of Confined Compression Tests C. Guide Specifications for Subsurface Drains D. Guide Specifications for Controlled Fill ATTACJ3MENT 1. Copy of January 8, 1974 Report A-1 B-1 c-1 D-1 ii Project No. 51218G-SI01 1. " .- I " I SOIL AND GEOLOGICAL INVESTIGATION FOR THE PROPOSED CARLSBAD OAKS (CT 74-21) CARLSBAD, CALIFORNIA This report presents the results of our soil and geologic investigation at the approximately 187-acre site of the pro- posed Carlsbad Oaks Industrial Complex. The site is north of and adjacent to Palomar Airport Road, approximately one mile east of its intersection with El Camino Real in the City of Carlsbad, California. The subject site is the extreme southern portion of a larger, approximately 600-acre area. PURPOSE AND SCOPE OF INVESTIGATION The purpose of our investigation was to assist Santa Fe Company and its consultants in evaluating the 187-acre site and in project design. This report presents our conclusions and recommendations regarding: General subsurface soil and geologic conditions Potential geologic hazards including landslides Presence and effect of loose or porous alluvial soils Expansive soils Slopes General site grading Pavements bearing pressures. Types and depths of foundations and allowable soil Additionally, we are presenting a preliminary opinion regarding feasibility of constructing fill pads along the toe Project No. 51218G-SI01 I - L area of an ancient landslide and conclusions regarding settle- ment characteristics of the canyon areas. Both of these areas are offsite in relation to the 187-acre site. DESCRIPTION OF THE PROJECT For our study, we have discussed the project with Mr. Barry Bender of Rick Engineering Company, and we have been provided with a site plan entitled IICarlsbad Airport Business Center, Tentative Map of C.T. 74-21," prepared by Rick Engi- neering Company (scale 1" = 200' ), initially dated September 12, 1974 with the latest revisions dated August 3, 1981. In addition, we have reviewed the following reports and photographs: 0 Disposal Systems, Carlsbad Oaks Industrial Center, "Feasibility Study for the Use of Individual Effluent San Diego County, California," prepared by Shepardson Engineering Associates Inc., dated September 21, 1978, 0 "Preliminary Rippability and Fault Location Studies, Loker Property, Carlsbad, California,If prepared by Woodward-Gizienski & Associates, dated January 8, 1974 (Project No. 73-281). Property, City of Carlsbad and San Diego County, Ca1ifornia,lt prepared by Woodward-Gizienski & Asso- ciates, dated November 27, 1973 (Project No. 73-281). Rick Engineering Company, dated July 24, 1981. Stereographic aerial photographs supplied to us by 0 ItPreliminary Engineering Geologic Study, Loker 0 We understand that the proposed project will include mass grading of the site to produce access roads, parking areas and approximately 38 level lots for the construction of one-story and two-story moderate-weight industrial buildings. We further 2 Project No. 51218G-SI01 i t I . .. 1 understand that minor regrading may occur on a lot by lot basis as the industrial complex is developed. Specific grading plans for the site are being prepared at this time. Preliminary plans indicate that cut slopes with heights of up to 40 feet have been tentatively proposed. We assume that cut slopes will have maximum inclinations of l+:l (horizontal to vertical). Proposed fill slopes are not clearly defined on the tentative map. Maximum fill slope heights of approximately 115 feet are anticipated. We assume that the proposed fill slopes will be designed with maximum inclinations of 2:l. The tentative map indicates maximum cut and fill depths of approximately 50 feet and 100 feet, respectively. This project represents the initial phase of a large industrial development which involves an additional approxi- mately 400 acres directly north of the site. The entire area has been the subject of previous preliminary soil and geologic studies by our affiliated firms. We understand that portions north of the boundary of the initial phase will require offsite grading in connection with the currently proposed project. FIELD AND LABORATORY INVESTIGATIONS Our field investigation included making a geologic recon- naissance of the existing surface conditions, making 11 small diameter auger borings, 9 large diameter borings, and 9 backhoe test pits between August 5 and September 8, 1981, and obtaining representative soil samples. The test pits and borings were advanced to depths ranging from 3% to 81% feet. The locations of the borings and test pits are shown on Figure 1. A Key to Logs is presented in Appendix A as Figure A-1. Logs of the borings are presented in Appendix A as Figures A-2 through A-41. The descriptions on the logs are based on field 3 Project No. 51218G-SI01 Wodward.Clyde Consultants I - I logs, sample inspection, and laboratory test results. Results of laboratory tests are shown at the corresponding sample loca- tions on the logs and in Appendix B. The field investigation and laboratory testing programs are discussed in Appendixes A and B. Geologic Settinq The subject site lies within the western San Diego County coastal region. This area is generally characterized by ero- sional remnants of gently westward dipping Cretaceous through Quaternary age sedimentary deposits that overlie and abut Jurassic age metavolcanic and Cretaceous age crystalline rocks to the east. Topography and Surface Conditions The site is bounded on the south by Palomar Airport Road and on the north by the south wall of a major east-west trend- ing canyon. A deeply incised northerly-trending canyon splits the site in half, producing two gently rolling mesa surfaces that are currently being cultivated. Elevations within the site range from approximately 470 feet (MSL Datum) at the high point of the east mesa surface, to less than 300 feet at the bottom of the canyon. Vegetation on the site consists of extensive agricultural cultivation and a moderate to heavy growth of brush and grasses in the drainages and along steep ridge slopes. Exposed man-made features on the site consist of a network of dirt roads and assorted support buildings fox the current agricultural activity. Subsurface utilities noted on the site during our investi- gation were shallow farm irrigation lines. An underground sewer pipeline exists on the southern side of the east-west trending canyon just north of the site. 4 Project No. 51218G-SI01 woodward.Clyde Consultants I The site is within the 50 to 1 flight path of nearby Palomar Airport. Subsurface Conditions The site is underlain by uncompacted fill soils, surficial topsoils, Quaternary age alluvium, and the Eocene age Santiago Formation. These units are underlain at depth by Cretaceous age granitic rock which is exposed to the north of the site. The onsite soils are described below; their areal extent, with the exception of the uncompacted fill soils and surficial top- soils is approximately shown on Figure 1. The geologic map symbol for each unit is given after the formal name for the unit. Uncompacted Fill Soils (Unmappedl. Silty sand and sandy to silty clay fill soils are present in the dirt roads through- out the site. These soils are in an uncompacted and compress- ible state, and are generally underlain by compressible allu- vial soils where the roads cross canyons and gullies, and by loose, uncompacted soil in side-hill road cut situations. Boring 20 indicates that the loose fill soils can be up to 20 feet deep. Topsoils (Unmapped). A topsoil layer, composed of porous silty sands to silty clays, is present over most of the site. We estimate that these soils are generally from 1 to 3 feet in thickness, although locally they may extend to a depth of up to 8 feet. Agricultural cultivation has loosened the surface soils to a depth of 4 to 1 foot on the flatter mesa surfaces. Alluvium (Qal). Recent alluvial deposits appear to be confined to the natural drainage channels on the site. The alluvial materials generally consist of sandy clays with some layers of clean sands. Based on our field investigation, we estimate that these deposits are on the order of 10 feet in maximum thickness in the canyons within the site limits and up to 25 feet thick in the east-west canyon to the north. 5 Project No. 51218G-SI01 woodward-Clyde Consultants I - I I t- I - 1- Santiago Formation (Tsr. Beneath the overburden soils, the site is underlain by the Eocene age Santiago Formation. This unit appears to be divided into two zones with silty to clayey sands dominating the section above an elevation of about 380 feet and silty to sandy clays prevailing below this ele- vation. Lenses and interfingerings of the clays and sands are common to both zones. The clayey section of the Santiago For- mation is expansive and is equivalent in age and in engineering characteristics to the Del Mar Formation and as such is sus- ceptible to landsliding. Structure In general, the bedding attitudes of the undisturbed Eocene age sediments in the study area range from essentially horizontally stratified to shallow dips (usually less than 5'). Information from our large diameter test borings indicates that the western mesa is characterized by southerly trending dips on the order of 5O, and the eastern mesa is characterized by northerly trending dips of approximately the same magnitude. Faulting and Seismicity A limited fault location study was performed on the site in November of 1973. The results of the study were presented in the Woodward-Gizienski & Associates report of January 8, 1974 (Attachment I). The locations of test trenches excavated for that study are shown on the Site Plan, Figure 1. In that investigation, one fault zone was discovered on the site rough- ly corresponding to a suspected fault lineation as construed from aerial photographs. The fault trace, found in Trench 2, did not appear to offset topsoils. In our recent test explorations on the site, an unmapped feature interpreted to be a minor fault trace was observed in Test Boring 12 at a depth of 31 feet. At that point the fault 6 Project No. 51218G-SI01 Woodward*clyde Consultants L trace trends in a northeasterly direction, dips approximately 40 degrees toward the northwest, and has a measurable offset of 12 inches. No nearby surface expression of the fault was observed in our reconnaissance or in our study of recent aerial photographs. The nearest known active fault along which earthquakes of magnitude 4 or greater have occurred is in the Elsinore Fault zone, mapped some 22 miles northeast of the site. The closest significant faulting is the northern extension of the Rose Canyon Fault zone, which is mapped offshore approx- imately 9 miles west of the site. No magnitude 4 or larger earthquakes have been recorded on the Rose Canyon Fault zone. Landslides Information from our large diameter test borings, geo- logical reconnaissance, and review of recent aerial photographs indicates that a large ancient landslide is present on the north-facing slope of the east mesa surface. Additionally, our information indicates areas of suspected landslides on either side of the known slide, and on the ridge in the vicinity of the northwest site boundary (see Figure 1). Ground Water Water was noted flowing in the bottom of the east-west trending canyon north of the site boundary, and at the lower elevations in the deeply incised northerly-trending canyon. Water seepage was present in several of our large diameter test borings, generally above elevation 300 feet. No other areas were noted in our geological reconnaissance that indicated abnormal wet or marshy areas. 7 Project No. 51218G-SI01 DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS The discussions, conclusions and recommendations presented in this report are based on the results of our field and lab- oratory studies, analyses, and professional judgment. Geologic Hazards Faulting and Seismicity. Our review of the geologic literature did not disclose the presence of known faults on the site. The fault traces encountered at depth in Test Boring 12 and at near-surface in Test Trench 2 of the previous study are not known to significantly offset the Tertiary age strata in the general area. In our opinion, the presence of these fault traces will have a negligible impact on the proposed grading. Landslides. Our data indicate the presence of a large, deep-seated ancient landslide along the northern slope of the eastern mesa surface. A dominant fracture was found at ap- proximate elevation 364 feet in Boring 9, and a remolded clay seam dipping at approximately 38'N was found at approximate elevation 294 feet in Boring 6. A geologic cross section (Figure 2) extending from the mesa rim to the canyon bottom indicates that this slide may extend to depths of 70 feet in the graben area. We were unable to physically locate the graben of this slide because of extremely steep terrain and thick brush, however, our cross section and recent information about proposed grading in this area indicate that the graben may extend to the toe area of the fill slope proposed for this area. We recommend that this area be closely examined by an engineering geologist from our firm during brushing operations to more accurately locate the graben area. Recommendations for relocating the toe of the proposed fill slope, if necessary, may be made at that time. Additionally, because of the prox- 8 Project No. 51218G-SI01 ! - i - imity of the slide and suspected slides in the area, we recom- mend that structures built on Lots 27, 29 and 31 be set back a minimum of 25 feet from the proposed' daylight cut line. Offsite grading is tentatively planned along the lower portion of this large slide. More detailed discussion of that grading is included under the heading Offsite Considerations. Although our large diameter test borings did not disclose remolded clay seams outside the area of the large slide in the east section of the site, topographic features and the dis- turbed and fractured appearance of subsurface soil lead us to suspect that landslides are present in north-west and north- east areas of the eastern half of the site. Current maps indicate that these areas are offsite. They are discussed under Offsite Considerations. Remolded clay seams dipping slightly into the slope were observed at depths of S+ feet and 18% feet in Boring 13 on the western mesa surface (see Figure 1). The in-slope dips of these seams indicate that they were possibly formed by bedding plane adjustments or regional tectonic movements. Topographic features and nearby test borings indicate that similar planes of weakness may exist in the adjacent easterly knoll. Plans indicate that fills up to a maximum depth of about 50 feet will be placed in this area. We recommend that an engineering geologist from our firm closely examine pad excavations and the fill slope toe key excavations in this area. Although we do not anticipate more adverse geologic conditions than we sus- pect, mitigating recommendations can be presented during grad- ing if necessary. Liquefaction. The Santiago Formation soils underlying the site are dense to very dense and there is no apparent shallow permanent ground water table within these formational soils. In our opinion, the formational soils do not have a potential for liquefaction. The loose, compressible alluvial soils in 9 Project No. 51218G-SI01 Hlbodward.Cly& Consultants " L the canyons bottoms have a low potential for liquefaction in their present state. In our opinion, this potential will be mitigated by densification as recommended under Grading. Ground Water Surface water is present in the alluvial soils in both the northerly-trending canyon in the center of the site and the east-west trending canyon offsite to the north. Seepage was also noted in several of our large diameter borings. The source of water seepage in the test borings is uncertain, however, we believe it to be the result of agricultural irriga- tion at the site and cultivated areas south of the site. Based on this information, we believe that there is a potential for ground water seepage from cut slopes and in canyon bottoms. We recommend that all cut slopes be observed by an engineering geologist from our firm during site grading. Specific loca- tions of slope seepage can be identified at that time. We recommend that one of the seepage control methods of the at- tached Guide Specifications for Subsurface Drains (Appendix C) be used to control cut slope seepage. Because of the seepage potential, we recommend subsurface drains be installed in the canyon bottoms in accordance with Appendix C and at the locations indicated on Figure 1. We recommend that positive measures be taken to properly finish grade each lot after structures and other immprovements are built so that drainage waters from the lots and adjacent properties are directed off the lots to the streets and away from building foundations, floor slabs, and slope tops. Even with these provisions, experience has shown that a shallow ground water or surface water condition can and may develop in areas where no such water condition had existed prior to site development. This is particularly true where a substantial increase in surface water infiltration results from landscape irrigation. 10 Project No. 51218G-SI01 I - L Slopes We evaluated soil strength parameters based on experience with similar soils on nearby projects and based on the plas- ticity characteristics of representative on-site soils from cut areas. Based on our evaluation, we selected the following soil parameters for our slope stability analysis: Soil C' (psfl y (pcfl Cut slope Ts clayey soil 25' 300 125 Cut slope Ts sandy soil 30' 200 125 Fill Slope Fill soil 30' 400 125 We performed stability analyses for the proposed slopes using the Janbu method. The results of these analyses indicate that slopes constructed in accordance with the following recom- mendations have calculated factors of safety in excess of 1.5 against deep seated failure under static conditions: Slope Soil - Slope Ratio Cut Ts (clayey) 1%: 1 Cut Ts (clayey) Cut Ts (sandy) 2:l 2:l Fill 2:l Allowable Height (feet) 40 25 115 50 Stability analyses require using parameters selected from a range of possible values. There is a finite possibility that slopes having calculated factors of safety, as indicated, could become unstable. In our opinion, the probability of slopes becoming unstable is low. We recommend that all slopes be constructed at slope inclinations no steeper than 2:l. Slopes constructed at in- clinations steeper than 2:l are particularly susceptible to shallow sloughing in periods of rainfall, heavy irrigation, and upslope runcff. Periodic slope maintenance may be required, 11 Project No. 51218G-SI01 including rebuilding the outer 18 to 36 inches of the slope. Sloughing of fill slopes can be reduced by over-building at least 3 feet and cutting back to the desired slope. To a lesser extent, sloughing can be reduced by backrolling slopes at frequent intervals. As a minimum, we recommend that fill slopes be backrolled at maximum &foot fill height intervals. Additionally, we recommend that all fill slopes be trackwalked so that a dozer track covers all surfaces at least twice. Soil and Excavation Characteristics Fill material generated from planned cuts will consist of expansive clays, sandy clays, clayey sands and silty to clean sands. The small diameter borings indicate that the less expansive material is in the upper zones of cut. These borings also indicate the probability of expansive soil at finish grade between approximate elevations 380 to 370 feet. Drilling characteristics of the small diameter borings in- dicate that excavation to proposed finish grades can be accom- plished with moderate effort using conventional grading equip- ment. Grading We recommend that we review the grading plans prior to their finalization to assess whether our recommendations have been incorporated. We recommend that a pre-grading conference be held at the site prior to the start of any grading. The owner or devel- oper, design engineer, grading contractor, and soils engineer should be in attendance. Questions concerning grading opera- tions can be resolved at that time. We recommend that all grading be done in accordance with the attached Guide Specifications for Controlled Fill (Appen- dix D). All grading should be observed by and compacted fills tested by our firm. 12 Project No. 51218G-SI01 Compressible soils consisting of loose cultivated soil, loose topsoil, uncompacted fill, and loose alluvial soil are present throughout the site. We' recommend that cultivated soils, topsoils, and uncompacted fill not removed during plan- ned grading be removed, brought to the proper moisture content, and recompacted prior to placing additonal fill or building structures. Our test borings and backhoe test pits indicate that compressible alluvial soils range from 2 feet deep in the upper reaches of the canyons to over 21 feet deep at the lower elevations of the site. We recommend that loose alluvial soils in the upper reaches be excavated, properly moisturized, and recompacted prior to the placement of additional fill. We anticipate that ground water will interfere with exca- vation and recompaction of alluvial soils in the lower eleva- tions of the major canyons on site. Plans indicate that fills ranging from about 20 feet to 100 feet are planned in these areas. For this case, we recommend that all loose soils, such as slopewash and uncompacted fill, be removed, the alluvial soil be scarified, and fill placed and compacted in accordance with specifications. Settlements will occur under the fill loads. Estimated magnitudes and settlement times are discussed under Settlements. Our small diameter borings indicate the probability of expansive soils at or near finish grade elevations in the western half of the site. We recommend that expansive soils, where encountered within 3 feet of finish grade, be excavated and replaced with nonexpansive soil to a minimum depth of 3 feet below bottoms of floor slabs and at least 12 inches 12 inches below the lowest footings proposed for each lot. We recommend the limits of undercut include the building dimen- sions plus an additional 5 feet on all sides. Since the exact building limits are unknown at this time, we recommend that any undercut limits be clearly defined on the grading plans at the conclusion of mass grading. 13 Project No. 51218G-SI01 woodward-Clyde Consultants We recommend that the upper 3 feet of material in fill lots consist of properly compacted nonexpansive finish grade soils. Nonexpansive soils are defined as those swelling less than 3 percent when recompacted to a minimum of 90 percent of maximum laboratory density, placed under an axial load of 160 pcf, and soaked in water. Foundations In our opinion, the proposed one-story or two-story moder- ate-weight industrial buildings may be founded on conventional spread or continuous footings. We recommend allowable soil bearing pressures of 2,000 psf and 3,000 psf, respectively, for footings founded a minimum of 12 inches and 24 inches below lowest adjacent grade in nonexpansive natural ground or non- expansive, properly compacted fill. Footings should be a minimum of 12 inches wide for 2,000 psf and 18 inches wide for 3,000 psf. The soil bearing pressures are for dead-plus-live loads, and may be increased up to a minimum of one-third for transient loads produced by wind or seismic forces. We recommend that structures that will not tolerate dif- ferential settlement (such as foundations, concrete decks, walls, pools, etc.) not be located within 8 feet of the top of slopes. In those areas where it is necessary to locate foot- ings in this zone, we recommend that they be extended in depth until the outer bottom edge of the footing is at least 8 feet horizontally from the outside face of the slope. We recommend that structures built on Lots 27, 29 and 31 be set back a minimum of 25 feet from the proposed daylight cut line. As each lot is developed, we recommend that finish grading and fowdation plans be reviewed by our office prior to final- izing. Additional recommendations for unusual foundation loading or expansive soil conditions can be presented in an addendum report for each individual lot, if required. 14 Project No. 51218G-SI01 " Settlements Typically, settlement rates in loose alluvial soils are dependent on material porosity, degree of saturation, pore pressure dissipation, and rate of applied load, such as com- pacted fill. The magnitude of settlement is generally depen- dent on the depth of loose material and the weight of the applied load. Laboratory tests indicate the soils are wet and should not be adversely affected by future introduction of water. We analyzed settlement characteristics of typical samples of alluvial soils from deeper than 10 feet. The re- sults of these analyses indicate that settlements of up to 19 inches could occur under fills of 100 feet for alluvial soils of thicknesses on the order of 25 feet. Figure 3 presents these results in graphical form. Because the rate of settle- ment is not instantaneous, we recommend settlement monuments be installed during grading and that monitoring continue after grading. No building should be built until settlement is completed. Pavements For our preliminary design we assumed Traffic Indexes of 4.5 €or car parking area, 5.5 for driveways and truck traffic areas, and 6.0 for the streets within the site. We also as- sumed R-values of the on-site soil would range from 10 to 30. We used the California Department of Transportation method for flexible pavement design and an R-value of 78 for Class 2 aggregate base material. calculated pavement sections are pre- sented in the following table: Traffic Index Asphalt Concrete Thickness (inches) Thickness (inches) R=lO R=30 R=lO R=30 Class 2 Base 4.5 6.0 5.5 3 3 3 3 3 3 7 11 4 7 12 8 15 I Project No. 51218G-SI01 We recommend 6-inch thick Portland Cement Concrete slabs with appropriately spaced control be used in trash dumpster and loading dock areas. We also recommend that R-value tests be performed on actual subgrade soils when they become apparent after grading is completed and utilities are in place. Modi- fications to pavement sections may be made at that time if necessary. The subgrade should be compacted for a depth of at least 6 inches to at least 95 percent of maximum dry density as determined by ASTM D1557-70. Class 2 aggregate base should conform to State of California Standard Specifications (1978), Section 26-1.02B. We recommend that asphalt concrete be pro- vided and placed in accordance with Section 39 of the above- mentioned California Department of Transportation Specifica- tions. We recommend that mix designs for asphalt concrete be made by an engineering company specializing in this type of work, and that the paving operations be inspected by a quali- fied testing laboratory. We recommend providing adequate surface drainage to reduce ponding and infiltration of water into the subgrade materials. Typical pavement surface slope requirements in the San Diego area are 1 to 1% percent. OFFSITE CONSIDERATIONS Highlands to the north of the east-west trending canyon are mainly composed of Cretaceous age granitic rock (Kgr) in varying stages of decomposition. The decomposition is irregu- lar and varies from very dense sands to angular cobbles and boulders to unweathered rock. We understand that the more weathered areas may be used as a borrow source for filling operations on the site. Jf oversize rocks are generated from borrow areas (rocks larger than 6 inches in maximum dimen- 16 Project No. 51218G-SI01 WoudwardmClyde Consultants sions), we recommend that they not be used in fills on the site. We suggest that any oversize rocks generated be stock- piled for possible use as riprap during future development. It is our understanding that approximately 7 acres of fill lots are proposed along the lower portion of the northern slope of the east mesa. Preliminary plans indicate that these lots will be constructed on the toe area of the existing slide. We were asked by Mr. Tchang to preliminarily evaluate the stabil- ity of the slide mass after fill was placed for the lots. For our analysis, we used our computer-based Morgenstern-Price method for wedge analysis. Based on information from our test borings, we selected a failure surface and analyzed the stabil- ity of the slide mass by itself, the slide mass with proposed fill, and the slide mass with proposed fill and buttress key. Figure 4 illustrates the configurations analyzed. Based on the assumed soil parameters, failure surface and fill configura- tions, our preliminary analysis indicates that it is feasible to construct the fill with the indicated buttress key. More detailed information is necessary prior to fill construction in order to provide a final evaluation of stability. This infor- mation should include locating the definite limits of the slide, the depth of any remolded clay seams at the buttress key, and undisturbed samples of the slip plane for more de- tailed strength evaluation. Alternate solutions to the existing slide area are: com- plete removal and recompaction of the disturbed soil; or permit no construction in the vicinity of the slide. Preliminary es- timates of complete removal indicate that approximately 700,000 cubic yards of soil are involved. Preliminary plans indicate that an access road may be constructed in the suspected slide Rrea of the northeast slope of the east mesa surface. We recommend that the access road not be constructed in this area: however, if it is necessary to 17 Project No. 51218G-SI01 Woodward-Clyde Consultants locate it there, we recommend that further in-depth investiga- tions be conducted in order to better define the actual extent of adverse geologic conditions. Preliminary plans also indicate that the access road will cross the graben area of the suspected slide on the northwest slope of the east mesa surface. We recommend that trenching operations to expose the actual geologic conditions of this area be conducted during brushing and grading. If this is an actual slide, we recommend that it be removed and recompacted prior to constructing any road or pad fill. Preliminary esti- mates indicate that approximately 80,000 to 100,000 cubic yards of soil could be involved in removal. RISK AND OTHER CONSIDERATIONS Our borings and test trenches represent only a small portion of the pertinent soil and ground water conditions when compared to the overall area of the site. The recommendations made herein are based on the assumption that soil conditions do not deviate appreciably from those found during our field investigation. If the plans for site development are changed, or if variations or undesirable geotechnical conditions are encountered during construction, we should be consulted for further recommendations. We recommend that we review the foundation and grading plans to verify that the intent of the recommendations pre- sented herein has been properly interpreted and incorporated into the contract documents. We further recommend that we observe the site grading, subgrade preparation under concrete slabs and paved areas, and foundation excavations. It should be understood that California, including San Diego, is an area of high seismic risk. It is generally con- sidered economically unfeasible to build totally earthquake- resistant structures; therefore, it is possible that a large or nearby earthquake could cause damage at the site. 18 Project No. 51218G-SI01 Woodward.Clyde Consultants Professional judgments presented herein are based partly on our evaluations of the technical information gathered, partly on our understanding of the proposed construction, and partly on our general experience in the geotechnical field. Our engineering work and judgments meet current professional standards. We do not guarantee the performance of the project in any respect. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's opera- tions, and we cannot be responsible for the safety of personnel other than our own on the site; therefore, the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. Contractual arrangements with the grading contractor should contain the provision that he is responsible for exca- vating, placing and compacting fill in accordance with the job specifications. Inspection by the geotechnical engineer during grading should not relieve the grading contractor of his pri- mary responsibility to perform all his work in accordance with the specifications. 19 i - 1- 0 0 0, 0 VI 0 0 0 Y) 0 0 f m m 1 " I. Project No. 51218G-SI01 APPENDIX A FIELD INVESTIGATION Woodward.Clyde Consultants For our investigation, twenty exploratory test borings and nine Figure 1. test pits were made at the approximate locations shown on Nine of the test borings were made with a truck-mounted bucket auger, and representative samples were secured. Eleven addi- tional borings were drilled using a 6-inch diameter, continuous flight power auger. Samples of the subsurface materials were obtained from these small-diameter borings using a modified California drive sampler (2-inch inside diameter and 2+inch outside diameter) with thin brass liners. The sampler was generally driven 18 inches into the material at the bottom of the hole by a 140-pound hammer falling 30 inches. The brass liner tubes containing the sample were removed from the sam- pler, sealed to preserve the natural moisture content of the sample, and returned to the laboratory for examination and testing. Bag samples were also taken of representative mater- ials. The test pits were made with a John Deere model 450-C trackhoe and disturbed samples were obtained from the exposed materials. The locations of the test excavations and the elevation of the ground surface at each location were estimated from the plan prepared by Rick Engineering Company. A- 1 Location Boring Number Elevation IT 12 110 65 1 nnERIUYCLE EST? NUMBER I SOIL DESCRIPTION ,a I Very dense, damp, brown silty sand (SM) 1 2 WATER LEVEL SOIL CLASSIFICATION At tim of drilling or as indicated. Soil CJIficatianr we bard on me Unified Soil CJanification Svatem and indude calor. moisture md ConaisenLy. Field dsrsriptwna have been modif& to nflcn rwlts of labaratow mdvm rr)len .Dprwiate. - DISTURBED SAMPLE LOCATION ObtVrud bv collecting me auper wttiw in a PIrstiC or cloth baa. - DRIVE SAMPLE LOCATION MODIFIED CALIFORNIA SAMPLER Ymple with mded bla par foot ws &tic4 with a Modified California drive ~mpler (I' lnrldr diamtsr. 2.5 ouulds dmmterl lined with YmpIe tubn. The umpln we% driwn into the mil at fhe bonom of the hole rrnh a 140 pound k.mmI Ialling 33 indIer INDICATESSAMPLE TESTED FOR OTHER PROPERTIES GS - Grain Size Dirtrlbvtlon CT - Conrolidntion Test LC - L.boratorv Compenmn UCS - Unmnlinad Compraaion Test PI - Attarberg Limits Teat OS- Dnut Shear Test ST - Loaded Swell Test CC- Contmd Cwnpmaion 'R'- R-value TX- Trirrial Comprmsion Test Test SDS -Slow Dirm Shear Test Tmt NOTE: In this column the r.wlu of thm testa MY b. recorded hre .ppliubla. BLOW COUNT DRY DENSITY Number 01 blow ded to advance aamplcr OM fwt or aa indicated. Pounds par Cubc Foot MOISTURE CONTENT brant 01 Dry Wemht NOTESON FIELD INVESTIGATION 1. REFUSAL wdicat" the irvbility toexNfd exCw.tion. Pr.sliullv. with Dqyopmnt being umd in th. inmtlgnlon. KEY TO LOGS CARLSBAD OAKS DRAWN my: ch I O)CEKED BV: pu I PROJECT WO: 51218G-SI01 I DATE: 8-13-81 I FIGURE MOA-1 WOODWARD-CLYDE CONSULTANTS Boring 1 6" H.S.A. Approximate El. 425' NUMBER -LE SOIL DESCRIPTION I Flrm, moist, dark brown silty clay (CH) yellow brown clayey sand (SC) SANTIAGO FORMATION 1-1 TOPSOIL 1-2 1-3 1-4 1-5 1-6 1-7 1-8 Very hard, moist, pale yellow brown to olive sandy clay (CL) SANTIAGO FORMATION sand (SM) SANTIAGO FORJlATION 1-1 moist, mottled light olive gray o dark yellowish brown silty to clayey sand SANTIAGO FORMATION .. ... .... :. clayey sand (SM-SC) .. . . SANTIAGO FORMATION YellW sandy Clay (CL) SANTIAGO FORMATION Very hard, moist, mottled, light olive reddish A clayey sand (SM-S *FW brsripiion 01 .ymb~tr. see Fipurr A-1 Continued on Next Page MG OF TEST BORING 1 CARLSBAD OAKS DRAWNIV: sh 1 CMECKE0IV:W 1 PRDJECTNO: 51218G-SI01 I DATE: 8-14-81 I FIQUREIK): A-2 , WOODWARD-CLYDE CONSULTANTS Boring 1 (continued) I. SOIL DESCRIPTION 1 Continued very dense, moist, pale Olive gray silty'to clayey sand (SM-SC) L SANTIAGO FORMATION Bottom of Hole DRAWNOY: sh I CnECKED0Y:pD 1 ?RDJECTN0:51218G-S101 I DATE: 8-14-81 I FlQUREI(O:A-3 WOOOWARD-CLYDE CONSULTANTS I " " T D1 'DD - 1 Boring 2 6'' H.S.A. Approximate El. 446' SAMPLE YVMBER SOIL DESCRIPTION I Very dense, moist to wet, pale olive gray silty uniform sand (SM-SP) SANTIAGO FORMATION Very dense, moist, pale olive yellow silty to clayey sand (SM-SC) SANTIAGO FORMATION . .... .. .. . ...... :..;'\ Very dense, moist, pale brown silty to clayey ..... sand (SM-SC) SANTIAGO FORMATION ..:.:. ... .... ,.. . .:.:.. j.:.;$d (SM) SANTIAGO FORMATION Very dense, moist, light olive gray silty to clayey sand (SM-SC) SANTIAGO FORMATION Very dense to very hard, moist, motrled olive gray and light reddish brown clayey sand to sandy clay (SC-CL) SANTIAGO FORMATION SANTIAGO FORMATION *For &uription of wn-bols. re Fwre A-1 Continued on Next Page LOG OF TEST BORING 2 CARLSBAD OAKS DRAWNBV: sh I CnECKE0BV:pD I WOJECTNO5~218G-SIOl I DATE: 8-14-81 I FIQURE NO:A-4 WOODWARD-CLYDE CONSULTANTS Boring 2 (Continued) I SOIL DESCRIPTION Very,dense, moist, light gray brown silty to clayej, sand (SM-SC) SANTIAGO FORMATION Very dense, moist, olive gray, clayey sand (SC) SANTIAGO FORMATION Very dense, moist, light olive gray silty sand (SM) SANTIAGO FORMATION Bottom of Hole 1 .For d.uription oi wmbols. we Fipure A-1 LOG OF TEST BORING 2 (Continued) CARLSBAD OAKS DRAWNBY: sh I CHECKEDBY:PD I PRWECTN0:51218G-SI01 I DATE: 8-14-81 I FIQURE W:A-5 - WOOOWARO*CLYDE CONSULTANTS 6" H.S.A. Boring 3 Approximate El. 405' LE SOIL DESCRIPTION I Loose, dry to damp, dark brown sandy clay (CH) ,I TOPSOIL Stiff to hard, moist, dark olive, silty clay (CH) SANTIAGO FORMATION " I: f. 1- c L- L _. 1 I I. . .. l;: ... Very dense, moist, yellowish brown clayey ~:. sand (SC) SANTIAGO FORMATION Very hard, moist, pale olive gray sandy clay (CL) SANTIAGO FORMATION SANTIAGO FORMATION SANTIAGO FORMATION SANTIAGO FORMATION *For ckrniption of sv~olr, LC Fwrt A-1 ZC)G OF TEST BORING 3 CARLSBAD OAKS DRAWNW: sh I CMECKEDBV:PD I CRDJECTNO 51218G-SI01 I DATE: 8-14-81 I FIOURE LK):A-6 WOODWARD-CLYDE CONSULTANTS T- Boring 3 (Continued) SOIL DESCRIPTION I I\ sand .with shells (SM) SANTIAGO FORMATION Continued very dense, moist to wet, gray silty \ sand (SM) Very dense, moist to wet, blue gray, silty SANTIAGO FORMATION Bottom of Hole LOG OF TEST BORING 3 (Continued) CARLSBAD OAKS DRAWNBV: sh I CHECKEDBV: PD 1 CRWECINO 51218G-SI01 I DATE: 8-14-81 I flOURE MD: A-7 WDODWARD-CLYDE CONSULTANTS k. I " I 1 5 i 40 Boring 4 6" H.S.A. Approximate El. 435' SAMPLE NVMBER SOIL DESCRIPTION 1 4-1 4-2 4-3 silty sand (SM) Very dense, moist, gray to pale reddish yellow Very dense, moist, gray white silty sand ISM) SANTIAGO FORMATION SANTIAGO FORMATION Color change to pale yellow tan Hard to very hard, moist, olive gray to olive silty clay (CH) SANTIAGO FORMATION ANTIAGO FORMATION 4 sandy clay (CL-CH) SANTIAGO FORMATION Very hard to dense, aoist, mottled, olive yellow sandy clay (CL) to very dense, moist, pale gray with yellow streaks silty sand (SM) Continued on Next Page SANTIAGO FORMATION .For &scriptoon of symbolr,re Fipure A-1 " b LOG OF TEST BORING 4 CARLSBAD OAKS DRAWNBV: sh I CHECKEDBV: pD I CRDJECTNO: 51218G-SI01 I DATE: 8-14-81 I FlOURLIK): A-8 WOODWARD-CLYDE CONSULTANTS Boring 4 (Cont'd) SOIL DESCRIPTION (Continued) very hard to dense, moist, mottled olive yellow sandy clay (CL) yellow streaks, silty sand (SY) to very dense, moist, pale gray with SANTIAGO FORMATION Very hard, moist, grayish purple with rust stains, silty clay (CL) SANTIAGO FORMATION Bottom of Hole *For dmacrtp~om ot symbols. LI Ftgure A-1 . LOG OF TEST BORING 4 (CONT'D) CARLSBAD OAKS DRAWN BY: ch I CHECKED BY: I PRWECT NO: 51218G-SI01 I DATE: 8-14-81 I FlOURE 110: A-9 WOODWARD-CLYDE CONSULTANTS Boring 5 6" H.S.A. Approximate El. 460' Color change to pale yellow Color change to orange Color change to pale yellow green Color change to orange Color change to ?ale orange to yellow clayey Color change to orange SANTIAGO FORMATION h ,-- SANTIAGO FORMATION " - OTHEi rEm - S,PI S,P1 - *For huription of syymbolr, me Fiwre A-1 Continued on next page LOG OF TEST BORING 5 CARLSBAD OAKS I WOODWARD-CLYDE CONSULTANTS .- " - WLE MER - Boring 5 (Cont'd) SOIL DESCRIPTION I dark gray to black, sandy Silty Clay (Cantinued) very dense to very hard, moist, (ML-CL) SANTIAGO FORMATION Very dense, moist, dark gray black, silty sand (SM) SANTIAGO FORMATION Bottom Of Hole .For dercriptton of rymbolr. ).e Fiwrc A-1 r LOG OF TEST BORING 5 (CONT'D) I CARLSBAD OAKS DllAWNW: ch I CHECKEDgV:PD I PROJECTNO 51218GS101 I DATE: 8-14-81 1 ClOURL110: A-11 WOODWARD-CLYDE CONSULTANTS Locntion Boring Number Elevation F -~ ;AMPLE JUMBER DESCRIPTION I 1 DISTURBED SAMPLE LOCATION 0bI.h.d by Cowkp IH MtW* h a plulk 0 Wh D.P KEY TO LOGS CARLSBAD OAKS WDDDYYARD-CLYDE CONSULTANTS .- I i - Boring 6 30" Diameter Bucket Auger Approximate El. 360' DESCRIPTION 1 Stiff, moist, dark brown, sandy clay (CL) TOPSOIL Medium dense, moist, pale yellowish brown, silty sand (SM) LANDSLIDE MATERIAL %"-l" silty claystone bed (CL) N80E 40s Silty clay bed N80E 42s Thinly laminated, olive, hard, silty claystone bed ~85E 345 ~~~~~~~ ~ ~ ~~~~ Medium dense, moist, gray to yellowish brown to yellowish orange, silty to clayey sand (SII-SC) very disturbed LANDSLIDE MATERIAL Silty clay interbed N85W 475 Silty clay interbed N85W 525 Very disturbed claystone bed Medium dense, moist silty sand bed (SM) Boring 6, (cont'd) DESCRIPTION (Continued) medium dense, moist, silty sand bed (SM) Base of silty sand N65W 555 material very disturbed with many open voids along Medium dense, damp, yellowish brown, silty sand (SM) fractures LANDSLIDE MATERIAL -4 c -5 I: -6 c -7 c 8-8 [ 1"-2" gray to brown silty clay interbe2 N58W 255 7 Slow water seep Medium dense to dense, gray, moist to wet, Clayey sand to sandy clay (SC-CL) LANDSLIDE MATERIAL Bedding attitude N76W 205 Grades into clayey sand Thin remolded fracture N71W 725 Medium dense, moist yellowish brown, Silty to clayey sand (SM-SC) LANDSLIDE MATERIAL 1' thick, firm organic rich layer above slip plane 1"-2" thick remolded clay basal Slip plane Ii52E 38N Hard, moist, dark gray, Silt to clay (ML-CL) SANTIAGO FORMATION Bottom of Hole I LOG OF TEST BORING 6 (Continued) CARLSBAD OAKS I DRAWN BY: Ch 1 CHECKEDBY:~D I CRWECTNO: 51218C-SI01 I DATE: 8-19-Cl 1 FIGURE NO:A-14 WOODWARD-CLYDE CONSULTANTS Boring 7 30" Diameter Bucket Augex ADDTO DESCRIPTION Stiff, moist, light brown silty clay (CHI TOPSOIL Dense, moist, light olive to pale yellowish brown mottled silty to clayey sand (SM-SC) SANTIAGO FORMATION -Cemented shell bed Stiff to hard, moist, olive silty clay (CL-CH) with yellowish oragne stains Light brown silty clay interbed Bedding attitude N65'E 3ONW Brown silty clay interved N65'E SoNW Stiff to hard, moist, gray with yellowish orange stains mottled silty to sandy clay (CL) SANTIAGO FORMATION Dark brown slightly cemented shell bed N80°E 8"N Continued on Next Page Boring 7 (Cont'd) t' - I. I - I DESCRIPTION 1 orange stains, mottled silty to sandy clay (CL) (Continued) stiff to hard, moist, gray with yellowish SANTIAGO FORMATION Dense to very dense, moist, brown to yellowish brown to gray mottled clayey to silty sand (SC-SM) SANTIAGO FORMATION Slow water seep from sand bed . Thinly laminated silty sand bed - N65'E 3-N Stiff, moist, brown silty to sandy clay (CL) SANTIAGO FORMATION End of Downhole log One hour after drilling Hard, moist, dark gray silty clay (CL) SANTIAGO FORMATION Very dense, saturated, brown medium grained clean sand (SP) SANTIAGO FORMATION Bottom of Hole * - Confined aquifer.water rose to 58' in about one hour *For dewrioroon of syhls. see Fiplre A-12 I LOG OF TEST BORING 7 (Continued) CARLSBAD OAKS I ._ " - I 'I - TESTS - Boring 8 30" Diameter Bucket Auger Approximate El. 350' DESCRIPTION Firm, moist, brown silty clay (CHI TOPSOIL Medium dense, moist, yellowish brown to olive mottled clayey sand (SC) SANTIAGO FORMATION Sand bed with concretion N70°E 7'N Irregular sand bed N68'W 15'N Shell bed N40'W 9'NE Shell bed N37'E 7ONW Stiff, moist, brown to yellowish brown silty to sandy clay (CL) SANTIAGO FORMATION Stiff, moist, gray to yellow brown silty clay (CL-CH) SANTIAGO FORMATIOX Sand bed Friable sand bed with shells at base N55'W SONE Yellowish brown silty sand bed (SM) with shells Wet near base, friable Silty gray to rust friable sand bed .For dmmiption of rymbclc,re Fwm A-12 Continued on Next Page 1 LOG OF TEST BORING 8 CARLSBAD OAKS DRAWN81: ah I CHECKED W:PI\ I PROJECT NO:53218G-SI01 I DATE: 8-19-81 1 FIGURE NOA-17 WOODWARD-CLYDE CONSULTANTS Boring 8 (Cont'd) I I - - TESTS - DESCRIPTION 1 (Continued) stiff, moist, gray to yellowish brown silty clay (CL,-CH) SANTIAGO FORMATION Hard, moist, olive gray silty clay (CL-CH) SANTIAGO FORMATION Bottom of Hole DRAWNBV: sh I CHECKEDBV:Pb I PROJECT NO:51218G-S101 I DATE: 8-19-81 FIGURE NO:A-18 WOODWARD4LYDE CONSULTANTS Boring 9 30" Diameter Bucket Auger Approximate El. 394' DESCRIPTION Medium dense, damp, brown clayey sand (SC) " 1- - " 40 " Medium dense, moist, yellowish brown silty sand (SM) LANDSLIDE MATERIAL Medium dense, moist, light brown clayey sand (SC) SANTIAGO FORMATION Mottled, light gray, yellow brown, pale brown to brown silty sand (SM) SANTIAGO FORMATION Dense, damp, light gray to brown silty sand (SM) SANTIAGO FORMATION -Pockets and discontinuous lenses of Olive Silty Clay 1 Bedding Attitude N63'W 18" Hard, damp, olive silty to sandy clay (CH) Dominant fracture - attitude N25'E 50"E - $ Continued on Next Page Boring 9 (Cont'd) p EOLOGl LMPL UMBE DESCRIPTION 1 (Continued) hard, damp, olive silty to sandy clay (CH ) SANTIAGO FORMATION Stiff to very stiff, damp, brown silty clay (CHI SANTIAGO FORMATION Color change to brown to olive Water seepage below 53%' ~ ~~ Hard, damp, dark gray silty to sandy clay (CH) Cemented sand bed SANTIAGO FORMATION 7 . 10" of water after 2 hours Bottom of Hole .For d.ylipim of svmbol*. see Foplrt A-12 I LOG OF TEST BORING 9 (Continued) CARLSBAD OAKS WOODWARD-CLYDE CONSULTANTS Boring 10 30" Diameter Bucket Auger Approximate El. 380' DESCRIPTION Medium dense, damp, brown, porous, clayey sand (sc) ! MPSOIL L RESIDUAL CLAY Hard, damp, brown sandy clay (CL) Dense, damp, light gray to light yellowish brown silty sand (SM) LANDSLIDE " I=-z -7" " = "" - " " 40 TEST8 ~ Medium dense, light brown silty sand (SM) Contact attitude N2OW 12'N 1" to 8" thich olive gray clay (CHI dip of 15" to NE LANDSLIDE Local bedding dips of 20-30°, cross bedding Bedding attitude N63"E 15'5 SANTIAGO FORMATION Hard, damp, light olive sandy clay (CL-CH) Very dense. damp, light olive silty to clayey sand (SM-SC) lenses of sandy clay (CL) Bedding attitude N51°W 15OS SANTIAGO FORMATION Hard, damp, gray silty to sandy clay (CL-CH) SANTIAGO FORMATION Hard, damp, brown silty clay (CH) SANTIAGO FORMATION Color change to olive -1 7 Continued on Next Page *For devrimion of svmaolr, *e Flwrc A __ I LOG OF TEST BORING 10 CARLSBAD OAKS I WOODWARD-CLYDE CONSULTANTS Boring 10 (Cont'd) I I - 1 \--- " " -7 "" " " = " - " "- "= " 45 "- 83 1 TESTS DESCRIPTION (Continued) hard, damp, brown silty clay (CHI SANTIAGO FORMATION Color change to brown and olive r Color change to olive Brown clay bed N48OE lOoS Dense, wet, brown silty sand (SM) with shell fragments SANTIAGO FORMATION - Hard, damp, brown silty clay (CH) SANTIAGO FORMATION Hard. damp. dark gray silty clay (CH) with shell fragments SANTIAGO FORMATION r Color change to dark olive gray Cemented sand bed Bottom of Hole LOG OF TEST BORING 10 (Continued) CARLSBAD OAKS WOODWAROXLYDE CONSULTANTS Boring 11 30" Diameter Bucket Auger Approximate El. 368' DESCRIPTION Hard, damp, light olive silty to sandy clay (CL-CH) SANTIAGO FORMATION (Estimate upper 2' including topsoil removed by grading) " " - 40 / Thinly laminated sandy clay Bed of silty sand N29'W 5'5 r Olive, less sandy " - - - GRADES TO - - - - - - - - Very stiff, moist, brown silty cla (CH) Irregular bed of yellow and brown silts SANT~AGO FORMATION Hard, damp, brown sandy clay (CH) Dense, moist, light olive silty sand (SM) ~~~ SANTIAGO FORMATION SANTIAGO FOREV+ATION \""" - GRADES TO - - - - - - - - Hard, damp, olive silty to sandy clay (CH) SANTIAGO FORMATION Continued on Next Page I I - - - - - - GRADES TO - - - - - - - Dense, moist, pale brown silty sand (SM) SANTIAGO FORMATION ""_ GRADES TO " - - "- Hard, damp, brown silty clay (CH) SANTIAGO FOWIATION - - - GRADES TO - - - - - - __ Dense, moist, pale brown clayey sand (SC) Very dense, moist, pale olive to pale brown silty sand (SM) . 5- .-5 SANTIAGO FORMATION 1-6 c - Thin layers of brown silty clay Hard, damp, brown silty clay (CH) SANTIAGO FORMATION color change to mottled brown and gray Hard, damp, dark gray sandy clay (CH) SANTIAGO FORMATION fragments SANTIAGO FORMATION Water seepage < Dense, moist, brown silty sand (St!) with shell Hard, damp, dark gray sandy clay (CHI SANTIAGO FORMATIO?I Bottom of Hole *Fordeuriptmn ot wmbals.rc F~plrr A-12 I LOG OF TEST BORING 11 (continued) 1 I CARLSBAD OAKS I DIAWNBV: sh I CWECKEDBY: Pb I CRWECTNO:51218G-S101 I DATE: 8-19-81 I FIGURE NO. A-24 WOOOWARO~CLYOE CONSULTANTS I - I/ Boring 12 30” Diameter Bucket Auger ate F1. 79R‘ DESCRIPTION I Hard, dry, brown sandy clay (CH) Very stiff, moist, brown silty. clay (CH) ”” ””” GRADES TO Very stiff, mottled, olive and yellow brown silty clay (CH) Bed of firm, moist clay, dips 5% Hard, moist, olive gray clay (CH) - Sandier Dense, damp, pale olive clayey sand (SC) Contact attitude N67’E 8”N Bed of hard, damp, olive silty Clay Hard. damp, olive sandy clay (CL) - Horizontal contact Bed of olive clayey sand Hard, damp, olive silty clay (CH) Dense, mist, olive brown clayey sand (SC) Fault, N56’E 40°N with thin remolded Clay, 1‘ Of displacement Very dense to hard, damp, olive clayey sand to silty clay (SC-CH) Hard, damp, gray to gray brown silty clay (CHI SANTIAGO FORMATION Continued on Next Page I CARLSBAD OAKS DRAWN BV: sh I CHECKED BV: QD I PROJECT NO: 51218G-SI01 I DATE: 8-19-81 I FIGURENO A-25 WOODWARD.CLYD€ CONSULTANTS Boring 12 (Cont'd) " I i - -5: -6t DESCRIPTION 1 (Continued) hard, damp, gray to gray brown silty clay (CH) Wet zone Color change to dark olive gray, harder drilling 1 Sandier Bottom of Hole Boring 13 30" Diameter Bucket Auger ADDro-e El. 363' DESCRIPTION I " I " Loose, dsy to damp, brown sandy clay (CH) CULTIVATED SOIL I (CL) Very stiff, damp, light olive to light brown sandy clay CULTIVATED SOIL Hard, damp, olive gray silty clav (CH) Bed of brown clayey sand N52'W 3'N at 33' Remolded clay seam at 54' 6" bed of white limey clay between 5t' to 6' with scattered shell fragments Dense, damp to moist, light brown silty sand (SM) =TIAGO FORMATION Dense, moist, light olive to pale brown silty to clayey sand (SM-SC) Light red brown silty sand at 10' SANTIAGO FORNATION Bed of light olive silty clay N14'E 3"s Stiff to very stiff, moist, olive silty clay (CH) Dense, moist, brown silty sand (SM) Remolded clay seam N25'E 4's Very dense, moist, light olive to pale brown silty to clayey sand (SM-SC) SANTIAGO FORMATION SANTIAGO FORMATION \ \ i S- SANTIAGO FORMATION t Highly cemented sand bed Banded sand N29'E 3'5 Coarse sands and shell fragnents Cemented sand bed Hard damp, olive silty clay (CHI \ SANTIAGO FORMATION Contact attitude: N48'E 8OS Sand lense Continued on Next Page CARLSBAD OAKS DRAWNIIV: sh 1 CHECKED6Y:PD I PRDJECTN0:51218G-S101 1 DATE: 8-19-81 I FIGURE NO: A-27 - .. .. .. WOODWARD-CLYDE CONSULTANTS Boring 13 (Cont'd) " EOLOG - 70 75 81.5 /!q . . . .- -. -_ " " . .. - AMPLI KJMBEl - 3-7c 3-8E 3-9[ DESCRIPTION I (Continued) hard, damp, olive silty clay (CH) SANTIAGO FORMATION Sand lense Hard, damp. brown to gray brown silty clay (CH) thinly laminated SANTIAGO FORMATION Hard, damp, olive gray silty clay (CH) Sandier at 52' SANTIAGO FORMATION r Color change to dark gray I ~~ ~~~~ Very dense, moist, pale olive clayey sand (sc) SANTIAGO FORMATIO!J Hard, damp, gray black silty clay (CH) Cemented sand bed Very dense, damp, gray sandy silt (ML) with scattered shells SANTIAGO FORMATION r Sandier SANTIAGO FORUSION - - - - - - GRADES - - - - - - - - Water seepage Very dense, damp, gray clayey silt (ML) SANTIAGO FORMATION LOG OF TEST BORING 13 (Continued) CARLSBAD OAKS 1 Boring 14 30" Diameter Bucket Auger Approximate El. 383' AMPLE WBER DESCRIPTION \ Loose, dry to damp, brown silty clay (CH) CULTIVATED SOIL Very stiff, moist, brown silty clay (CH) Dense, damp, pale olive to light brown clayey sand SANU (SCt SANTIAGO FORMATION Sandy clay seam at 5' Silty sand with shell fragments at 7' 14- Dense, moist,light olive to pale brown silty sand (SM) \ \ \ Contact attitude N21°W 3"s SANTIAGO FORMATION : SANTIAGO FOF34A ION laminated SANTIAGO FORMATION Dense, moist, brown silty to clayey sand (SM-SC) Hard, moist, light olive sandy clay (CL) Contact attitude N36'W 4's SANTIAGO FORMATION 14-2 ~ Dense, moist, pale olive silty sand (SM) Pale yellow sand bed N30'W 3'5 at 19' 14- Hard, damp, olive silty clay (CHI SANTIAGO FORMATION - ~~~ Dense, moist, pale olive silty to clayey sand (SM-SC) Stiff, moist, olive gray silty clay (CH) \ SANTIAGO FORMATION 14-4- Firm, moist, very weak clay at 263' (2" layer) 14- Hard, moist, olive sandy clay to clayey sand (CL-SM) SANTIAGO FORMATION Hard, damp, olive silty to sandy clay (CHI SANTIAGO FORNATION 'For dewription of svmbols. YI Fwre A-12 r""" Continued on Next Page LOG OF TEST BORING 14 CARLSBAD OAKS DFAWNBY: sh I CMECKED0Y:PD I PROJECTNO: 51218~-~101 I DATE:8-19-81 1 FIGURE NO: A-29 WOODWARD-CLYOE CONSULTANTS Boring 14 (Cont'd) DESCRIPTION (Continued) hard, damp, olive silty to sandy clay (CH) SANTIAGO FORMATION Hard, damp, brown silty clay (CH) thinly laminated SANTIAGO FORMATION Hard, damp, olive gray sandy clay (CH) Sandier ~~ SANTIAGO FORMATION Sandier Very dense, moist, gray silty sand (SM) SANTIAGO FORMATION Bottom of Hole .For dewrimion 01 wmbols. Y. Ftpurr ~-12 I LOG OF TEST BORING 14 (Continued) CARISBAD OAKS 1 WOODWARD-CLYDE CONSULTANTS - SAhWL NUMB€ - 15-1 15-2 15-3 15-4 - Boring 15 6" H.S.A Approximate El. 287' r Sol L DESCRIPTION 3 :\ Y I I Soft, saturated, dark gray, silty to sandy clay (CH-CL) ALLUVIUM Water flowing in canyon bottom 1 I ! i Stiff, wet, pale yellowish brown, silty Clay (CH) ALLWIUM I Stiff, moist, yellowish brown to olive to light gray, silty clay (CL-CH) SANTIAGO FORMATION ~ ~~ Bottom of Hole - SAMPLt NWBEI 16-1 16-2 Boring 16 Approximate ~l. 264' SOIL DESCRIPTION r\ Soft to firm, moist, dark gray, silty to' sandy clay (CH) ALLUVIUM Water flowing in canyon bottom Firm, moist, yellowish brown to olive to gray, mottled silty clay (CHI ALLUVIUM mottled sandy clay (CL) Stiff, moist, yellowish brown to gray, / SANTIAGO FORMATION medium sand (SM) SANTIAGO FORMATION Very dense, moist, olive gray, silty Bottom of Hole WOODWARD-CLYDE CONSULTANTS .- . .. - BC - 11 15 32 53 'O/ 4 " JTHEI 'ESTY AMPLE UMBER .7-1 I .7-2 I .7-3 1 .7-4 I Boring 17 Approximate El. 251' SOIL DESCRIPTION Soft, moist, dark brown, silty Clay (CH) ALLWIUM I Material becoming more yellowish brown to gray mottled colored, some organic debris Medium dense, saturated, yellowish gray, silty sand (SM-SP) ALLWIUM Very dense, moist, gray, silty to clayey sand (SM-SC) SANTIAGO FORMATION Bottom of Hole 'Far drrcriptmn of rvrnbolr. see Fwre A-1 LOG OF TEST BORING 17 CARLSBAD OAKS I DRAWNBY: ch 1 CnECKE0EY:~D I CRDJECTNO: 5121%-SI01 1 DATE: 10-7-81 I FIGURENC A-33 WOOOWARD.CLYOE CONSULTANTS - 4 WC - - 10 30 46 io/ 6' NUMBEI SAMPLf 18-1 18-2 18-3 - 18-4 Boring 18 Approximate El. 249' SOIL DESCRIPTION I Soft to firm, moist to wet, dark brown, I sa;& clay (CL-CH) ALLWIUM ! 1 Material becomes more yellowish brown colored with a few thin silty sand interbeds Water in sands at 8'1' Medium dense, saturated, gray, silty sand (SM-SP) ALLWIUM Very dense, moist to wet, gray, silty to clayey sand (SM-SC) SANTIAGO FORMATION Bottom of Hole DRAWN BY: ch I CHECKED BY: PD I PROJECT NO: 51218G-SI01 I DATE: 10-7-81 I FIGURE NO: A-34 , ..--._.I WOODWARD-CLYDE CONSULTMTS 9 19 10 53/ 6" - WMPLE WMBER 19-1 19-2 19-3 19-4 Boring 19 Approximate El. 256' SOIL DESCRIPTION w : .:.. .I x . . . /.:. .. . . .. .... . .,. . . . . .. .. . ..... Loose, saturated, gray, silty to clayey .. . sand EM-SC) ALLUVIUM .. . .. . .. ::: .. ... ... . .. . ... ..;. . . .. .. .. ,..:. . I. . .. ., . j.. $..:...!I :.q Very dense, moist, gray, silty to clayey . .... sand (SM-SC) SANTIAGO FORMATION Bottom of Hole WOODWARD-CLYDE CONSULTANTS - BC - 7 14 10 9 35 - t SAMPLE lUMEEl 20-1 20-2 20-3 20-4 20-5 - Boring 20 Approximate El. 320' SOIL DESCRIPTION 1 Uncompacted, damp, pale yellowish brown to gray mottled silty sand FILL Material becomes more clayey and moist and colored Soft, moist to Wet, dark brown to black sandy clay (CL-CH) ALLWIUM . stiff, moist, yellowish brown to gray. mottled, silty to sandy clay (CL-CH) SANTIAGO FORMATION I Bottom of Hole DEPTH 3THLI lEITE - SAMPLE NWBER 21-1 21-2 [ - Test Pit 21 Approximate El. 335' SOIL DESCRIPTION 1 Stiff, moist, dark brown silty clay (CL) ALLWIUM Stiff, moist, olive silty clay (CL) SANTIAGO FORMATION 1 Bottom of Hole Test Pit 22 Approximate El. 293' i SOIL DESCRIPTION I Soft, saturated, black to light brown silty to sandy clay (CL) ALLUVIUM Water flowing in canyon bottom \ silty sand (SM) SANTIAGO FOPAATION Dense, wet, gray to pale yellowish brown Bottom of Hole WOODWARD-CLYDE CONSULTANTS Test Pit 23 i. 4 FEET .= li 15 :_I DEITH 15 l- T DATA DTHEl rEm - Approximate El. 308' 1 MPLE IWER I SOIL DESCRIPTION I Soft, wet, brown silty clay (CL-CH) ALLUVIUM Water flowing in canyon bottom Finn, moist to wet, mottled yellowish brown to gray to olive, silty clay (CL-CH) ALLWIUM Stiff, moist to wet, mottled yellowish brown to gray to olive silty clay (CL-CHI \ SANTIAGO FORMATION Bottom of Hole Test Pit 24 Approximate El. 286' Bottan of Hole *Ford.rcriplion of symbolr.vm Fipure ~-1 L LOG OF TEST PITS 23 AND 24 CARLSBAD OAKS DRAWNBY: mrk I CHECKEDBY: pB I CRDJECTNO: 51218G-SI01 I DATE: 9-9-81 1 FIGURENO: A-38, WOOOWARO-CLYOE CONSULTANTS Test Pit 25 Approximate El. 325' SOIL DESCRIPTION 1 Stiff, moist, brown silty to sandy clay (CL'-CH) ALLWIUM .. DECTM ~ E FEET 5 I T DATA - WPLE IVkgER - 25-1[ Dense, moist, pale olive silty sand (SM) SANTIAGO FORMATION .. . Bottom of Hole Test Pit 26 SOIL DESCRIPTION Loose to medium 'dense, moist to wet, dark brown sandy clay (CL) ALLWIUM .. .... .. Loose, saturated, light brown silty sand (SM) water flowing rapidly from layer 4 ALLWIUM n Dense, wet, olive gray silty to clayey sand (SM-SC) SANTIAGO FORMATION *For description of symbols. we Figure ~-1 LOG OF TEST PITS 25 AND 26 CARLSBAD OAKS DRAWN BV: mrk I CHECKED BY: [ PRDJECT NO: 51218G-SI01 I DATE: 9-9-61 I FIGURE IK). A-39 WOODWARD-CLYDE CONSULTANTS 7 FEET *w CLLT 15 t 3THER lESTS Test Pit 27 Approximate El. 248' 1 SOIL DESCRIPTION Loose, saturated, dark olive gray silty to alayey sand (SM-SC) ALLmuM Hole caving 7 - Loose, saturated, mottled dark yellowish brown to olive, silty to clayey sand (SM-SC), water flowing in rapidly Bottom of Hole Test Pit 28 Approximate El. 248' ALLWIUM olive gray clayey sand (SC) WWIUM *For dercrlptton 01 symbols. see Fwre I LOG OF TEST PITS 27 AND 28 CARLSBAD OAKS I DRAWN BY: mrk I CHECKEDEY:?~ I PROJECTNO: 51218G-SI01 I DATE: 9-9-81 FIGURE WO: A-40 WOODWARD-CLYDE CONSULTANTS Test Pit 29 " MPLE MBER Approximate El. 300' 1 SOIL DESCRIPTION I Very dense, damp, light reddish brown silty sand (SM) DECOMPOSED GRANITE Bottom of Hole (Digging very slow) DRAWN BY: mrk 1 CHECKEDBY:PD 1 PRDJECTNO: 51218G-SI01 1 DATE 9-9-81 1 FIGURENO:A-41 WOODWARD-CLYDE CONSULTANTS Project No. 51218G-SI01 APPENDIX B LABORATORY TESTS The materials observed in our test excavations were visually classified and evaluated with respect to strength and swelling characteristics, dry density, and moisture content. The clas- sifications were substantiated by performing grain size analy- ses and evaluating plasticity characteristics of representative samples of the soils. Confined compression tests were per- formed to evaluate settlement characteristics of the alluvium. The results of tests on drive samples are shown with the pene- tration of the sampler at the corresponding sample location on bution curves are shown on Figures B-1 and B-2. Results of the logs, Figures A-2 through A-41. The grain size distri- confined compression tests are shown on Figures B-3 and B-4. B-1 GRAVEL I SAND Caarse I Fine ICoerrel Medium I Fine I SILT and CLAY 1 krh Opening - Ins Sieve Sires Hydrometer Analysis I I I 1 *U - Liquid Limit .PI - Plasticity index GRAIN SIZE DISTRIBUTION CURVES CARISBAD OAKS WOODWARD-CLYDE COWSULTAWTS 'I "L 1.. " i ' "^ " " COBBLES BRAVEL I SAND brr8e I Fine ICoarsel Medium I Fine I SILT and CLAY 1 k8h Opening - Ins Sieve Sires Hydrometer Analysis t 1 I I 0 . W: W 10 m m BO 10 90 0 100 10.0 bo I BRAIN SIZE IN MILLIMETERS *U - Liquid Limit .PI - Plasticity Index I GRAIN SIZE DlSTRlBLITlON CURVES CARLSBAD OAKS DRAWNBY: ch I CHECKEDBY:pg PRQ)ECTN0:51218G-S101 I DATE: 8-25-81 I FIGURE NO:B-2 WOODWARD-CLYDE CONSULTANTS RESULTS OF CONFINED COMPRESSION TESTS Water onten1 ituratio % - 100 Carpress ion .- RESULTS OF CONFINED COMPRESSION TESTS Initial kter mten % _= 23 lturatior % - 97 lens i ti Dry ==3 pcf 105 - Fiml kter mtent - Bturatiol x - 100 ressure Carpress ion psf I % of Initial Heigh I - 3000 3.5 4 5 I CONFINED COMPRESSION TESTS CAFUSBAD OAKS DRAWN BY: ch CHECKED BY: p~ I PROJECT NO: 51218G-SI01 I DATE: 10-19-81 I FIGURE NO: B-3 WOODWARD-CLYDE CONSULTANTS - 6. . .. I: L " Project NO. 51218G-SI01 APPENDIX c GUIDE SPECIFICATIONS FOR SUBSURFACE DRAINS I. DESCRIPTION gravel enclosed in filter fabric with perforated pipe shall Subsurface drains consisting of Filter gravel or clean be installed as shown on the plans in accordance with these specifications, unless otherwise specified by the engineer. 11. MANUFACTURE Subsurface drain pipe shall be manufactured in accordance with the following requirements. Perforated corrugated ADS pipe shall conform to ASTM Designa- tion F405. Transite underdrain pipe shall conform to ASTM Designation C-508 (Type 11). Perforated ABS and PVC pipe shall conform to ASTM Desginations 2751 and 3033, respect- ively, for SDR35; and to ASTM Designations 2661 and 1785, respectively, for SDR21. The type pipe shall conform to the following table. Pipe Material Maximum Height of Fill (feet) ADS (Corrugated Polyethyiene) 8 Transite 'underdrain' 20 PVC or ABS: SDR35 SDR21 100 35 111. FILTER MATERIAL Filter material for use in backfilling trenches around and over drains shall consist of clean, coarse sand and gravel ments. or crushed stone conforming to the following grading require- Sieve Size 3/4" 3/8" 1 " 4 8 30 200 50 Percentage Passing Sieve 100 90 - 100 40 - 100 25 - 40 18 - 33 5 - 15 0- 7 0- 3 This material generally conforms with Class I1 permeable material in accordance with Section 68-1.025 of the Standard Spccifications of the State of California, Department of Transportation. c-1 IV. FILTER FABRIC Filter fabric for use in drains shall consist of Mirafi 140 (Cclanese), Typar (DuPont), or equivalent. The aggregate aggregate. Filter fabric shall completely surround the shall be 3/4-inch to l-l/Z-inch maximum size, free draining aggregate. V. LAYING Trenches for drains shall be excavated to a minimum width of 2 feet and to a depth shown on the plans, or as directed by the engineer. The bottom of the trench shall then be covered full width by 4 inches of filter material or with filter fabric and 4 inches of aggregate, and the drain pipe shall be laid with the perforations at the bottom and sections shall be joined with couplers. The pipe shall be outlet or storm drain. laid on a minimum slope of 0.2 percent and drained to curb After the pipe has been placed, the trench shall be back- filled with filter material of l-l/Z-inch maximum size agqregate if filter fabric is used to the elevation shown on the plans, or as directed by the engineer. c-2 r- - I. TYPICAL SUBSURFACE DRAItIS FOR LOCAL SEEPAGE Typical Seepage ilter I4aterial or Filter Fabric 6" Perforated Pipe Drain to Curb Outlet or Storm Draic Line ,-Compacted Native Soil ypical Seqa~s Line Filter l4aterial or Filter Fabric Drain to Curb Outlet or Storm Drain c-3 - -. TYPICAL SECTION SUBSURPACE DRAINS IN DRAWS (DRAIN PIPE IN TRENCH FILLED WITH FILTER MATERIAL) 1 ORIGINAL GROUND MATERIAL PIPE ADS (CORRUGATED POLYETHYLENE) TRANSITE UNDERDRAIN PVC or ABS: SDR 35 SDR 21 ABOVE BOTTOM OF ALLUVIAL CLEANOUT (FT.) MAXIMUM HEIGHT OF FILL 8 20 35 100 c-4 I - 1 TYPICAL SECTION SUBSURFACE DRAINS IN DRAWS (DRAIN PIPE IN TRENCH FILLED WITH CRUSHED ROCK ENCASED IN FImR MATERIAL) 1 ORIGINAL GROUND PIPE MATERIAL ADS (CORRUGATED POLYETHYLENE) TRANSITE UNDERDRAIN PVC or ABS: SDR 35 SDR 21 ABOVE BOTTOM OF ALLUVIAL CLEANOUT (FT.) MAXIMUM HEIGHT OF FILL 20 8 100 35 c-5 PROJECT NO. 51218G-SI01 APPENDIX D GUIDE SPECIFICATIONS FOR CONTROLLED FILL “a M r- .I .e I I. GENERAL These specifications cover preparation of existing surfaces to receive fills, the type of soil suitable for use in fills, the control of compaction, and the methods of testing compacted fills. It shall be the contractor’s responsibility to place, these specifications. A soil engineer shall be the owner’s spread, water and compact the fill in strict accordance with vation and the placing of fill shall be under the direct representative to observe the construction of fills. Exca- observation of the soil engineer, and he shall give written notice of conformance with the specifications upon completion permitted only upon written authorization from the soil of yrading. Deviations from these specifications will be engineer. A soil investigation has been made for this project; any recommendations made in the report of the soil investiga- tion or subsequent reports shall become an addendum to these specifications. 11. SCOPE The placement of controlled fill by the contractor shali in- clude all clearing and grubbing, removal of existing unsatis- spreading and compaction of fill in the areas to be filled, and factory material, preparation of the areas to be filled, all other work necessary to complete the grading of the filled areas. I I I. MATERIALS imported or excavated from the cut areas that, in the opinion 1. Materials for compacted fill shall consist of any material of the soil engineer, is suitable for use in constructing fills. The material shall contain no rocks or hard lumps of material smaller than +-inch in size. (Materials greater greater than 24 inches in size and shall contain at least 40% than 6 inches in size shall be placed by the contractor so thay they are surrounded by compacted fines; no nesting of rocks otherwise improper nature s.h.all be used in filling. shall be permitted.) No material of a perishable, spongy, or 2. Material placed within 36 inches of rough grade shall be select material that contains no rocks or hard lumps greater ted as hereinafter specified for compacted fill and soaked than 6 inches in size and that swells less than 3% when compac- under an axial pressure of 160 psf. D- 1 I i a M , ,I lo P -4 I - I 3. Representative samples of material to be used for fill shall be tested in the laboratory by the soil engineer in order to determine the maximum density, optimum moisture content, and classification of the soil. In addition, the soil engineer shall determine the approximate bearing value of a recompacted, saturated sample by direct shear tests or other tests applic- able to the particular soil. 4. During grading operations, soil types other than those analyzed in the report of the soil investigation may be en- countered by the contractor. The soil engineer shall be con- sulted to determine the suitability of these soils. COMFACTED FILLS General Unless otherwise specified, fill material shall be com- pacted by the contractor while at a moisture content near the optimum moisture content and to a density that is not less than 90% of the maximum dry density determined in accordance with ASTM Test No. D1557-70, or other density test methods that will obtain equivalent results. Potentially expansive soils may be used in fills below a depth of 24 inches and shall be compacted at a moisture content greater than the optimum moisture content for the material. Clearing and Preparing Areas to be Filled All trees, brush, grass and other objectionable material posed of by the contractor so as to leave the areas that shall be collected, piled, and burned or otherwise dis- have been cleared with a neat and finished appearance free from unsightly debris. All vegetable matter and objectionable material shall be removed by the contractor from the surface upon which the fill is to be placed, and any loose or porous soils shall be removed or compacted to the depth shown on the plans. The surface shall then be plowed or scarified to a minimum depth of 6 inches until the surface is free from uneven the equipment to be used. features that would tend to pr,event uniform compaction by Where fills are constructed on hillsides or slopes, the slope of the original ground on which the fi1.l is to be placed shall be stepped or keyed by the contractor as shown on the figure on Page 4 of these specifications. The steps shall extend completely through the soil mantle and into the underlying formational materials. D- 2 (d) After the foundation for the fill has been cleared, plowed or scarified, it shall be disced or bladed by the contrac- tor until it is uniform and free from large clods, brought to the proper moisture content, and compacted as specified for fill. 3. Placing, Spreading, and Compaction of Fill Material (a) The fill material shall be placed by the contractor in layers that, when compacted, shall not exceed 6 inches. Each layer shall be spread evenly and shall be thoroughly mixed during the spreading to obtain uniformity of mater- ial in each layer. (b) When the moisture content of the fill material is below that specified by the soil engineer, water shall be by the contractor until the moisture content is as specified. (c) When the moisture content of the fill material is above that specified by the soil engineer, the fill mat- other satisfactory methods until the moisture content is shall be aerated by the contractor by blading, mixing, or as specified. (d) After each layer has been placed, mixed and spread evenly, it shall be thoroughly Compacted by the contractor to the specified density. Compaction shall be accomplished by sheepsfoot rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of acceptable compacting equipment. Equipment shall be of such design that it will be able to compact the fill to the specified density. Compaction shall be continuous over the entire sure that the desired density has been obtained throughout area, and the equipment shall make sufficient trips to in- the entire fill. (e) The surface of fill slopes shall be compacted and there shall be no excess loose soil on the slopes. V. INSPECTION 1. Observation and compaction tests shall be made by the soil he can state his opinion that the fill was constructed in ac- engineer during the filling and compacting c2erations so that cordance with the specifications, 2. The soil engineer shall make field density tests in ac- cordance with ASTM Test No. 0155664. Density tests shall be made in the compacted materials below the surface where the D-3 surface is disturbed. When these tests indicate that the den- sity of any layer of fill or portion thereof is below the specified density, the particular .layer or portion shall be re- worked until the specified density has been obtained. " VI. PROTECTION OF WORK 1. During construction the contractor shall properly grade all excavated surfaces to provide positive drainage and prevent ponding of water. He shall control surface water to avoid damage to adjoining properties or to finished work on the site. The contractor shall take remedial measures to prevent erosion of freshly graded areas and until such time as permanent drain- age and erosion control features have been installed. 2. After completion of grading and when the soil engineer has finished his observation of the work, no further excavation or filling shall be done except under the observation of the soil engineer. Strip as specified ,. - . . Original ground .. . L sliding does not occur See Note NOTES : The outside edge of bottom key llA1l shall be below topsoil or loose surface material. The minimum width IIBlr of bench shall be 2 feet wider &an the compaction equipment, and not less than 10 feet. Keys are required where the natural slope is steeper than 6 horizontal to 1 vertical, or where specified by the soil engineer. D- 4 - Project No. 51218G-SI01 I Woodward-clyde Consultants ATTACHMENT I lha kK land Oeurlopnt -any Sola Beach. Callfornia 92075 P. 0. Box AG Attmtlon: Mr. A1 Kern - PRELIMINARY RIPPABILITY AND FAULT LOCAT10;1 STUDIES LOKIR PROPERTY URLSBAD. CALIFORNIA tapany. we have made additional studies at the subject site. The purpose In accordance with the request of Mr. Lyle Qbrielson of Rick Enginnrlnp of the studies was to provide preliminary rippability characteristics at rrlrted locations in the aranitics on the northern half of the site and to rake a limited investigation of possible faults In the southeast purrtw of the site. TRe mgineering reismgraph traverses wee made at the approxlnate locations lndluted on the attached Figure 1. on Hovder 28 and 29. 1973, under the supervision of 6 project Englr.eer!n- pt,k.$~;. l?o:ul:: of ttc:: tram%: are reported in the attached Table 1. 6ur interpretation of the results bared on our experience with nom1 heavy grading equipment In there types of =terials are smmrized kla for your convenience. . . Traverse No. DcDth-Fwt Smeral RiDpabilit~ ST-1 0-9 9-26 26+ Rippablr brdtrline Blast ST-2 O-28* ST-) 0-9 9-28* ST-) 0-55 . ST4 0-27* I ST-6R ST4 n-7 n4 0-17 17-w* 0-26* 0-26* 0-1 6 Rippabl, Rippable brdcrllne Rippable Rippablr Rlppabla brdrrlinr Rippable Rippablr Rlpprblr '. mts bta Indttate that *re IS a mlatlvely iaqe varlatlm tn UN &th rtwlals withln a depth of approximtely 25 feet or greater an eltHr of rfppable material across the site. In gmeral tt appears that the. rl able or borderllne. It has been our experience that the zones indlutd u To rdcrllm may or my not be excavated with nom1 heavy gradlng quipmt. This Is generally a functlon of the quallty of the quipnnt used, the stn and nadcr of rippers and the operator technlqw. Qlr experience has also been that granitlcs. sinilrr to those encountend rn tk northern half of the site. yield large dlameter unweathered boulders vpon exav&tlon. It Is suggested that the grading plans Include a nthod md location for disposal of these boulders. For exaple. boulders up to rppruximately 4 feet in slze could be placed in compacted fills under controlled conditlons by isolatlng the boulders such that there Is rwm for conpaction qulprnt to compact the roll around each boulder, and provlde proper Capactlon of the solls; boulders that are larger than 4 feet in slze could elthcr be placed In dlsposal areas of nonstructural fills or could k wed for decoratlon on lots. Three test trenches were mde O!I Nomber 30. 1973 under the dlrection of a project engineering geologfst at the approxlmte locations Indicated on the attached figure 1. There tnnchcr were made for the purpose of rcqulring additlonal infonnation as to the presence of faults. As dlrcussed In our report dated November 27. 1973. the aerial photographs give strong lndlcatlons that three possible faults exist on the property. The approxlnute p).ISence of faults us encountered in Trench 1 and Trench 3; however. a locations are indicated on the attached figure. No infornution raparcing test trenches 1s represented graphlcally on the attached Logs of Tart Trenches. fault was encountered in Trencn 2. lhe wterials as encountered In the wide. It 1s polnted out that this fault docs not appear to offset the Flgure 2. The Log of Trench 2 shows a fault zone of aDpmximately 2 fwt toprolls at.the trench lacatton. Thts fault has a trend of approximtely north 5 de rees east and dlps toward the east at approximately 67 degncs. The genera s alignment is In concordance with the anticipated locatlon from will need to be done regardlng the faults, their allgnncnt and their activlty inspection of the aerlal photographs. It is our oplnion that more work in the soil invertigatlon phase of studles on the site. It Is polnted out horrwr. that the County of kn Olego map entitled 'Faults and Epicentm" dltrd Novanber. 1973, shows no faults in this area. If you have any questions or if we can be of further senlce. please call at your convenience. Ihc kK Land kveloprnt -any Rick Engineering Carprny If L