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HomeMy WebLinkAbout; Civic Operations Center; Soils Report; 1982-06-14- - - - - SOIL INVESTIGATION AND CEOLCGIC RECONNAISSANCE - - - - - CIVIC OPEMTIONS CE!nYER CARLSBAD, CALIFORNIA For CITY OF CARLSBAD Carlsbad, California BY GEOCON, INCORPORATED San Diego, California June, 198.2 -_ .-~~ -. -. -. -_ GEOCON INCORPORATED ENGWEEBSANDGEOLOGISTS l CONSIJLTANTSINTHEAPPLIEDEARTH SCIENCES File No. D-2751-501 June 14, 1982 City of Carlsbad Engineering Department 1200 Elm Avenue Carlsbad, California 92008 Attention: Mr. Larry C. Dossey Subject: CIVIC OPERATIONS CENTER EL CAMINO REAL CARLSBAD, CALIFORNIA SOIL INVESTIGATION ANO GEOLnGIC RECONNAISSANCE Gentlemen: In accordance with your authorization and our proposal of February 4, 1982, we have performed a soil investigation and geologic reconnaissance for the subject project. The accompanying report presents the findings from our study and our recommendations relative to the geotechnical engineering aspects of developing the project as presently proposed. In general, the site was found to be underlain by moderately to high ex- pansive near-surface soils. Therefore, selective grading and/or special foundations will be required. It is our opinion, however, that the site may he developed as presently proposed, provided the recommendations of this report are implemented within design and construction. Should you have questions concerning our report or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, \d AD:PlSC:JEL:lm (6) addressee Staff Geologist n 9530 DOWDY DRIVE l SAN DIEGO, CALIFORNIA 92126 l PHONE (714) 695-2880 TABLE OF CONTENTS Page - - - - - - -. SOIL INVESTIGATION AND GEOLOGIC RECONNAISSANCE Purpose and Scope. ..................... Site and Project Description ................ Field Investigation. .................... Figure 1, Site Plan. .................... Laboratory Tests ....................... Soil and Geologic Conditions ................ Topsoils.. ....................... Point Loma Formation ................... Granitic Rock. ...................... Geologic Hazards ...................... Groundwater. ........................ Faulting and Seismicity. .................. Ancient Landslides ..................... CONCLUSIONS AND RECOMMENDATIONS General ........................... Grading ........................... Foundations. ........................ Concrete Slabs-on-Grade. .................. Site Drainage.and Moisture Protection. ........... LIMITATIONS AND UNIFORMITY OF CONDITIONS ............ APPENDIX A Figure 2, Log of Test Trenches 1 and 2 ........... Figure 3, Log of Test Trenches 3 and 4 ........... Figure 4, Log of Test Trenches 5 and h ........... Figure 5, Log of Test Trenches 7 and 8 ........... Figure 6, Log of Test Borings 1 and 2. ........... Figure 7, Log of Test Boring 3 ............... Figure 8, Log of Test Boring 4 ............... APPENDIX B Table Bl, Compaction Test Results. ............. Table B2, Moisture-Density and Direct Shear Test Results . . Table B3, Expansion Test Results .............. Table B4. County Class III Base Suitability Tests. ..... Tests from Testing Engineers ................ APPENDIX C Recommended Grading Specifications ............. 1 1 3 4 5 5 6 6 6 5 7 8 8 9 10 11 12 13 14 A-l A-2 A-3 A-4 A-5 A-6 A-7 B-l B-2 B-2 R-3 B-4 c- 1 GEOCON - - - - - - - - - - - File No. D-2751-501 June 14, 1982 SOIL INVESTIGATION AND GEOLOGIC REXONMISSANCE Purpose and Scope We have performed a soil investigation and geologic reconnaissance for the proposed City of Carlsbad Civic Operations Center. The purpose of our investigation was to evaluate the surface and subsurface soil and geologic conditions at the site and, based on the conditions encountered, to provide recommendations relative to the geotechnical engineering aspects of devel- oping the site as presently proposed. The investigation consisted of a site geologic reconnaissance, the drilling of four exploratory borings and the excavation of eight exploratory trench- es. Laboratory tests were performed on selected representative soil samples obtained at various depths in the test borings and trenches to evaluate pertinent physical properties. The conclusions and recommenda- tions that follow are based on an analysis of the data obtained and our experience with similar soil and geologic conditions. The irregularly-shaped site consists of approximately 28.9 acres of unde- veloped land generally located in the northeast quadrant of the intersection of El Camino Real and Palomar Airport Road in Carlshad, California. The site is immediately north of the existing County Solid Waste Transfer Station. The majority of the property slopes moderately to - l- Gl3OCON - - -. - - - - - - - - - - - - - - - File No. E-2751-501 June 14, 1982 gently down toward the southwest and is bounded on the north and east by a steep-walled natural drainage course. Vegetation at the site consists of moderate to dense growths of native weeds, grasses and brush. It is our understanding that it is proposed to develop the site to receive police and public works facilities. Additional City related facilities may be added at a later date although specific plans are not available. It is anticipated that the proposed structures would be a maximum of three stories and utilise slab-on-grade construction. No basements will be involved. It is further understood that site grading will consist of a balanced cut/ fill operation resulting in a general sheet grading at 52 percent downward slope to the southwest. The natural drainage ravine within the southeastern area of the site is designated as open space at this time. The maximum anticipated cut and/or fills will be on the order of 15 to 20+ feet. The locations and descriptions contained herein are based upon a site reconnaissance and discussions with Mr. Larry C. Dossey, principal civil engineer, City of Carlsbad. Should project details vary significantly from those outlined, Geocon, Incorporated should be notified for review and pos- sible revision of recommendations presented herein. -2- GIZOCON - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 Field Investigation The field investigation was performed on EZay 24 and 27, 1982 and consisted of a site reconnaissance, the drilling of four exploratory borings and the excavation of eight exploratory trenches at the approximate locations shown on the attached Site Plan, Figure 1. The borings were drilled to depths ranging from 10 to 15 feet below exist- ing grade utilizing a Mobile B-50 truck-mounted rotary drill rig equipped with 6-inch-diameter continuous flight auger. Relatively undisturbed samples were obtained by driving a 3-inch O.D. split tube sampler into the undisturbed soil mass with blows from a 140-pound hammer falling 30 inches. The sampler was equipped with l-inch-high 2-3/8-inch-diameter brass sampler rings to facilitate sample removal and testing. The trenches were advanced to depths ranging from 5 to 15 feet below exist- ing grade using a JD 510 rubber tire backhoe equipped with a 24-inch-wide bucket. Disturbed bulk samples were obtained at selected locations in the trenches and returned to our laboratory for testing. During the investigation, the soils encountered were continuously examined, visually classified and logged. Logs of the exploratory borings and trenches are presented in Appendix A. The logs depict the depth and des- cription of the various soil types encountered and include the depths at which sampling was performed. -3- GBOCON - - - - - - - - - - - - - - - File No. D-2751-JO1 June 14, 1982 /F--j, /- r ; ; ,, --iTe2 { 38 -~+.p%:o /-\ e i/-‘- --. “‘\,,\ .‘. -;/ . -...:I-‘/;/ f4i,/ .\ ----. ~/ d-‘1, ( g3 ‘\,\! \ ,T’\ \ p,,, ,,,,/ @;-J ‘\ 7 L- ,,I / /’ l _)lO----~~-~-. / \ I’ / ,/’ KY T-y ‘\‘Z ---- -“,’ p..-- ,,/’ f, ‘I,,. \ ‘\ .’ \, __~ J” -B-z y-2 . ..\ _.-- 2. \\ \ ‘. -\ \ ‘\ ‘\_ /’ \ ; \ i ,’ -_*c LEGEND ~~~.~dWPROX. LOCATION OF TEST BORING 4~---.APPROX. LOCATlON OF TEST TRENCH Kp..~.-..POINT~LO*IA FORMIOTlON Kqr ______. GRANITIC ROCK SITE PLAN CIVIC OPERATIONS CENTER CARLSBAD, CALIFORNIA VGURE 1 GEOCON, INCORPORATED 1 PAGE 4 GEOCON - - - - - - -. File No. D-2751-501 June 14, 1982 Laboratory Tests Laboratory tests were performed in accordance with ,generally accepted test methods of the American Society for Testing and Materials (ASTM) and other suggested procedures. Selected relatively undisturbed drive samples were tested for their in-place dry density, moisture content and expansive potential. The maximum dry density and optimum moisture content of representative samples of the prevailing site soils were determined in accordance with ASTM Test Procedure D1557-70, Method C. Direct shear and expansive tests were then performed on samples remolded to approximately 90 percent of maximum dry density at near optimum moisture content. In addition, "R" value, sand equivalent and grain size distribution testing was performed on a representative sample of decomposed granitic rock to aid in the evaluation relative to the suitability for use as pavement base materials. The results of our laboratory tests are summarised in tabular form in Ap- pendix B. In-place moisture-density relatlonships are also presented on the logs of test borings, Appendix A. Soil and Geologic Conditions Three soil types were encountered at the site during our investigation: - - -5- GEOCON File No. B-2751-501 June 14, 1982 - - - - topsoils, Cretaceous Point Loma Formation and Cretaceous granitic rocks of the Southern California batholith. Each of the soil types encountered is discussed below. Topsoils. Topsoils consisting of slightly clayey sands to highly ex- pansive clays were encountered in all of our exploratory excavations. The predominant topsoil is characterised by stiff to hard, dark brown, sandy clay which overlie the majority of the site to an average depth of approx- imately 2 feet. These materials are moderately to highly expansive and will require special handling as recommended under "Conclusions and Recom- mendations" hereinafter. Point Loma Formation. Formational mudstones and sandstones of the Point Loma Formation were encountered above an approximate elevation of 365 to 375 feet MSL near the northeastern portion of the site. Bedding within the formation varies from alternating beds of mudstone and fine sandstone to massive mudstone. Conglomeratic lenses were also encountered near the base of the formation. The formational soils are characteristically very dense, and the mudstone facies possesses moderate to high expansive potential. Granitic Rock. Granitic rocks of the Southern California batholith underlie the Point Loma Formation, and outcrops appear locally over the - - -6- - - - - - - - - - File No. E-2751-JO1 June 14, 1982 portion of the site not overlain by Point Loma Formation. The granit its exist at the site in varying states of decomposition, consisting of clayey and silty, well-graded sands near the ground surface, becoming more dense with depth. The results of our trenches and borings indicate that the material will be rippable to the depth of proposed cuts, but local, rela- tively unweathered zones could be encountered, requiring heavy ripping or blasting. In general, however, it is our opinion that blasting will not be necessary if cuts do not exceed 15 feet in depth. Results of laboratory tests performed on samples of decomposed granitic soils from the site indicate that much of the material will be suitable for use as County Class III base rock. Periodic sampling and testing of the material should be performed during excavation to ascertain that it con- forms to the appropriate specifications. Groundwater Although groundwater was not encountered during our Investigation. each of the geologic units, as well as the surficial deposits encountered on the site, have permeability characteristics and/or fracture systems that could be susceptible under certain conditions to water seepage. Inasmuch as no springs, seeps, or groundwater occurrences were observed, or are known to occur on the site, it is our opinion that the seepage potential is rela- tively low. It is our recommendation, however, that periodic inspection be - - - - 7- - - - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 made by either our soil engineer or engineering geologist during grading and/or construction for the presence of groundwater. Remedial measures, if any, will then be recommended. Faulting and Seismicity No active faults are known to exist at the site or in the immediate vicin- ity. The nearest active faults are the Elsinore and San Jacinto Faults which lie approximately 21 miles and 45 miles, respectively, to the north- east. An offshore extension of the potentially active Rose Canyon Fault zone has been mapped approximately 7 miles southwest of the site (Map No. 1, California Division of Mines and Geology); It is our opinion that the site could be subjected to moderate to severe ground shaking in the event of a major earthquake along any of the above mentioned faults. However, the site is not subject to any greater seismic risk than that of the imme- diately surrounding developments. Ancient Landslides No evidence of ancient landslides was observed at the site during our investigation, and no landslides are known to exist at locations which would affect development of the site as presently proposed. -a- - - - - - - - - File No. D-2751-501 June 14, 1982 CONCLUSIONS AND RECOMMENDATIONS General 1. It is our opinion no adverse soil/geologic conditions were encountered during the course of our investigation which would preclude the development of the City of Carlsbad Civic Operations Center as presently proposed, pro- vided the recommendations of this report are followed. 2. The results of our field observations and laboratory testing indicate that the near-surface topsoil over the majority of the site and the soils of the Point Loma Formation encountered above an approximate elevation of 365 to 375 feet MSL possess moderately high to very high expansion poten- tial. Thus, depending on proposed finish grades, unless a selective grading program is adopted, it is anticipated that soils within 3 feet of finish elevation will be sufficiently expansive to warrant special foundation design criteria. A selective grading procedure would place only soil with low expansion potential (3 percent or less) in the upper 3 feet beneath foundations, slabs and other improvements sensitive to differential movements. 3. In general, the underlying decomposed granitic rock was found to be nondetrimentally expansive. In addition, results of laboratory testing indicate that much of the material will be suitable for use as County Class III base rock. - - - -9- - - - - - File No. D-2751-501 June 14, 1982 4. It may be warranted for final site grading plans to consider lowering finished grades in conjunction with the exportation of decomposed granitics from the southern portion of the property such that the expansive onsite soils could be placed within the lower reaches of fills and capped with decomposed granitics cut from the northern site area. 5. Groundwater seepage was not encountered during our investigation. Therefore, no groundwater related problems are anticipated. However, control of surface drainage due to storm runoff and excess irrigation is considered an important design consideration. Foundation recommendations presented herein are contingent upon the implementation of drainamendations. Grading 6. All grading should be performed in accordance with the "Recommended Grading Specifications" contained in Appendix C. Where the recommendations of this portion of the report conflict with those of Appendix C, this sec- tion of the report takes precedence. 7. Site preparation should begin with the removal of all deleterious matter and vegetation. The depth of removal should be such that materials to be used in fills is free of organic matter. - - - -IO- - - - - - - - - - - - File No. D-2751-501 June 14, 1982 8. All ground to receive fill should be scarified to a depth of 12 inches, moisture conditioned and recompacted to specification of structural fill as discussed below. 9. The site should then be brought to final subgrade elevation with structural fill compacted in layers. The upper 3 feet beneath proposed buildings and the upper 1 foot beneath concrete flatwork and asphaltic pavements should consist of nondetrimentally expansive soil. All fill should be free of vegetation, debris and other deleterious materials and contain no particles larger than 6 inches in diameter. Layers of fill should be no thicker than will allow for adequate bonding and compaction. A thickness of 6 to 8 inches may be assumed to be satisfactory for this project. All fill (including backfill) should be compacted to at least 90 percent of maximum dry density at optimum moisture or above as determined in acordance with ASTM Test Procedure D1557-70, Method A or C. - - - Founda&ions 10. The site is suitable for the use of isolated spread and/or continuous strip footings. For foundations as described herein, an allowable bearing capacity of 2000 psf is recommended for design when considering dead plus realistic live loads and may be increased by one-third for transient loads. 11. Where selective grading has been performed as previously discussed, foundations should extend a minimum depth of 12 and 18 inches below adja- -ll- - - - - - - - - - - File No. D-2751-501 June 14, 1982 cent finished pad grade for single-story and two- to three-story struc- tures, respectively. The minimum recommended footing reinforcement should consist of two continuous No. 4 steel reinforcing bars placed horizontally, one near the top and one near the bottom of the footing. 12. Where selective grading has not been performed, the minimum footing depth should be increased to 24 inches and reinforcement should be in- creased to two No. 4 bars top and bottom for all structures. 13. Twelve inches is the minimum recommended footing width. Retaining Walls 14. The earth pressure against project retaining walls will depend upon the degree of restraint, slope inclination of backfill and, backfill mate- rials. The following table presents recommended earth pressures for cantiveler retaining walls with varying backfill conditions. Inclination of Backfill Equivalent Fluid Pressures level 35 pcf 2:l 45 pcf 1.5:1 55 !xf Where the retaining walls will be restrained from lateral movement at the top, a uniform pressure of 7H psf, where H equals the height of the wall in feet, should be added to the active soil pressure. - - - 12- - - - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 The above recommendations assume backfill will consist of properly com- pacted, free-draining granular soils. Lateral Loads 15. Lateral loads may be resisted by passive earth pressure. Passive earth pressures against shallow spread-type footings and/or ~11s. poured neat to undisturbed natural soils or in contact with properly compacted backfill, should be considered being equal to the forces exerted by a fluid of 350 pcf unit weight. A coefficient of friction 0.4 may be used between the bases of footings and slabs and the soil for computing the resistance to sliding. Concrete Slabs-on-Grade 16. Where selective grading has been performed, concrete slabs-on-grade should have a nominal thickness of 4 inches and he underlain hy at least 2 inches of clean sand or gravel. Reinforcement should consist of 6x6-10/10 welded wire mesh placed in the middle to upper third of the slab. Where moisture sensitive floor coverings are planned, the slab should be under- lain by a v&queen moisture barrier. A 2-inch-thick layer of sand or gravel should be provided above the visqueen to allow proper concrete curing. 17. hlwre selective grading has not been prformed as previously dis- cussed, slab reinforcement and bedding thickness should be increased to No. - - -13- GEOCON - File No. E-2751-501 June 14, 1982 3 reinforcing bars at 18-inch center-to-center spacing in each direction and 6 inches respectively. The No. 3 reinforcing bars should be bent at the periphery of the structure and extend down to the bottom of footing excavations. - - - - 18. The use of weakened plane, expansion and construction joints is rec- ommended to assist in controlling cracking in concrete slabs-on-grade. Site Drainage and Moisture Protection 19. Providing and maintaining adequate site drainage and moisture prow& tion of supporting soils is an important design consideration. Foundation recommendations presented herein assume proper site drainage will he estah- lished and maintained. - - - - - - 20. Under no ci&umstances should water be allowed to pond adjacent to footings. The site should be graded such that surface drainage flow is directed away from structures and into swales or other controlled drainage facilities. - - 14- GEOCON - -. - - - - - - - - - - File No. D-2751-301 June 14, 1982 LIMITATIONS AND UNIFORMITY OF CONDITIONS 1. The recommendations of this report pertain only to the site investigation and are based upon the assumption that the soil conditions do not deviate from those disclosed in the investigation. Our investigation was performed, our findings obtained and our recommendations prepared in accordance with generally accepted engineering priciples and practices at this time and location. Thus, it is our professional opinion that the soil/geologic conditions presented in this report are representative of actual site conditions. Our opinion means only that we performed our services in such a manner as to have reasonable certainty that significant conditions have been evaluated. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that planned at the present time, Ceocon, Incorporated should be notified so that supplemental recommendations can be given. 2. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field. 3. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, - - -15- GEOCON -. - - - - - .- - - - - - - - - - File No. D-2751-501 June 14, 1982 whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Where site development as described herein has not commenced within a three-year period from the date of this report, the recommendations presented herein should be re- viewed by a qualified soil engineer to ascertain if modifications are necessary. Where site development has commenced within the three-year period or is proposed for phase development, recommendations presented herein are considered applicable for project duration assuming proposed site development plans remain constant. - - -16- GEOCON - - - - - - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 , moist, dark brown, Silty Sandy CLAY with occasional boulders to 12" e, humid, orange- Ine to coarse SAND , moist, dark brown, Silty Sandy :.igure 2, Log of Test 'Trenches 1 and 2 A-l GEOCON - - -. - - - - - - - - - - - - .- - File No. D-2751-501 June 14, 1982 - *of nr,to ‘d - - - - - - - - - - TRENCH NO. 3 TOPSOIL Stiff, moist, dark brown, Sandy CLAY \ POINT LOMA FORMATION Dense, moist, orange-brown, Clayey Sandy CONGLOMERATE, cobbles to 3" \ diameter, Formation dips 3O-4'SE Hard, humid, gray-brown MUDSTONE (massive) TRENCH TERMINATED AT 15.0 FEET TOPSOIL TRENCH NO. 4 Medium dense, humid, orange-brown, \ slightly Clayey Silty, fine to medium DECOMPOSED GRANITICS Very dense, humid, orange-brown, slightly Clayey Silty, fine to coarse SAND TRENCH TEFUSAL AT 5.5 FEET ON ROCK DR” O.FN.WT, P.C., BULK iAMPLE 'lest 'Wenches 3 and 4 A-2 - - - - - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 - . 0.. - 2- -4- ; - 6- - 8- -4. 1 - 6- T6-1 )' -a- ., - * lo-' Figure 4, L LOG !JCU/Ic OF WPh - 3 y ;iJ$:‘. ,‘fl;:l$ ,.$ : -:I::,$ ::j:. ;gili $& m :.,:.. ., .:. ,: / ::.:; ‘;I: I’[ .; :1:1:j: $ij 1 ., ,: :l.,I’ : ,:I$ :!;;I)! u - plvda LW*ti - - TeS renches 5 and 6 TRENCH NO. 5 TOPSOIL Hard, humid, dark brown, Sandy CLAY \ DECOMPOSED GRANITICS Dense, humid, orange-brown, slightly Clayey Silty, fine to coarse SAND TRENCH REFUSAL AT 7.5 FEET ON ROCK TOPSOIL TRENCH NO. 6 Stiff, moist, dark brown, Sandy CLAY DECOMPOSED GRANITICS Dense, humid, light orange-brown, Silty fine to coarse SAND TRENCH TERMINATED AT 10.0 FEET A-3 BULK IMPLE - - - - - - - - - - - - - - - - - - - File No. D-2751-501 June 14, 1982 - S."F-c 106 * -sm oE*cP,P,,o/ow ," Nuuea Lcc4no~ Rss,- #ES, OF abvam .wMP‘E 0. TRENCH NO. 7 : ;;?$;: TOPSOIL 1.K Medium dense, humid, brown, slightly Clayey Silty SAND I"-P‘"Cf DR" "oI*Tu*~ DENC/TI COYTENT AC., % av d Dense, humid, orange-brown, slightly Clayey Silty, fine to coarse SAND BULK SAMPLE TRENCH TERMINATED AT 9.0.FEET 10- 0 TRENCH NO. 8 I:.'- :,<::..:: TOPSOIL :.;.:;:.. / Medium dense, humid, dark brown, Clayey 2- I' :' ,'..' (>y& SAND C?,b;'.::.: POINT LOU FORMATION 4. g$ Dense, moist, orange-brown, Clayey Sandy CONGLOMERATE, cobbles to 3" diameter 6. $;:$ :.k& a. ",.;:g ,_ i :..:. '. ,,:::,::.:.: DECOMPOSED GRANITICS lo- ..,I: 1:.J" Dense, moist, light orange-brown, '$j'>j. slightly Clayey Silty, fine to coarse / SAND 12- %jjj;.g . . . 14- Xgure 5, Log Of Test Trenches 7 and 8 A-4 - _- -. - - - - - - - -~ - ._ -. .-. - File No. D-2751-501 BORING NO. 1 TOPSOIL Medium dense, dry, light brown, Silty i-EL- -- Hard, moistxdark, Sandy CLAY with rock fragments to 2" diameter .._..._. ,,. - ~. .~ .__. ~~~.-.~--...-~ \ DECOMPOSED GRANITICS Very dense, humid, yellow-olive, Silty, i medium to coarse SAND !--not recovered BORING TERMINATED AT 15.0 FEET TOPSOIL BORING NO. 2 Medium dense, dry, light brown, Silty 2z.L~~~~~ Hard, moist, dark brown, Sandy CLAY \ DECOMPOSED GRANITICS Very dense, humid, yellow-olive, Silty, i fine to coarse SAND L-becomes olive BORING TERMINATED AT 10.0 FEET NO RI BULK JERY jAMPL1 Figure 6, Log of Test Borings 1 and 2 A-5 - - - - - - - - - - - - - - - - - - File No. D-2751-501 1__^^ 1 I. ,001 JULLS I-+, L7YL IN-PUCC wni SlYCLE LOG a Rme671* DEXRIPmw IN MuIIlER LGanm RnsJw DR” MblS~“M fc?7 OF Blanm DENslrl Cov?w~ YUP‘E AC.f % dV vi BORING NO. 3 TOPSOIL Medium dense, humid, orange-brown, 8- 10- 12. 14. 16. Dense, humid, yellow-olive, Silty, medium to coarse SAND $I..':: $$;=z---- hardrock "floater" ;.j.;.$j; ij,jii/: g;,j: :.@j$-‘==---- hardrock "floater" .';ii il<; i BORING TEWINATED AT 15.0 FEET i...__^ 7 r^- -c T.^^& D^__<_^ 7 rgu” I, Lug VI IcaL DurL,lg J A-6 GEDCON File No. D-2751-501 T....,? 1,. 1 OQ)l) - - - - - - - - - - - - - - - - - - - humid, dark gray-brown, Sandy -becomes very moist POINT LOMA FORMATION edium dense, moist, light brown, very layey Silty SAND ------ moist, orange-brown, slightly Clayey, Silty, fine to medium SAND -- Dense, humid, light yellow-olive, slightly Clayey Silty, medium to coarse -hardrock "floater ,I' near refusal rrg:ure 3, Log or l~esc mring 4 A-7 GEOCON - - - - - - - - - - File No. D-2751-501 June 14, 1982 TABLE Bl Summary of Laboratory Compaction Test Results A.S.T.M. D1557-70 Sample NO. Tl-1 Tl-2 T2-1 T3-1 T6-1 Description Maximum Dry Optimum Density Moisture pcf % Dry Wt. Dark brown, Silty Sandy 127.3 CLAY (TOPSOIL) Orange-brown, Silty, fine 126.7 t0 coarse SAND (DECOMPOSED GP.ANITICS) Dark gray-brown, Sandy '100.2 MLJDSTONE (POINT LOMA FORMATION) Dark gray-brown MUDSTONE 97.4 (POINT LOMA FORNATION) Light orange-brown, Silty, 129.5 fine to coarse SAND (DECOMPOSED GRANITIcs) 9.4 10.3 22.6 24.5 9.5 - - - B-l - - - - - - - - - - - - - - - - - File No. D-2751-301 June 14, 1982 TABLE B2 Sumnary of In-Place Moisture-Density and Direct Shear Test Results Sample NO. Tl-1" Tl-2" Tz-l* T3-1* Bl-1 B3-1 B4-1 Sample NO. Tl-l* T2-l* T3-1* Bl-1 B4-1 Dry Depth Density ft. pcf o-3 114.3 5-8 114.3 7-11 90.3 8-12 86.8 2 110.4 - 2 109.4 5 93.3 Moisture Unit content Cohesion % psf 9.5 10.0 22.4 26.0 17.4 18.0 25.7 350 21 420 38 430 32 440 32 TABLE B3 Summary of Laboratory Expansion Test Results Moisture Content Expansion (+) Before After or Test Test Dry Settlement(-) Depth Density Surcharge Angle Of Shear Resistance Degrees -- -- -- Description ft. % % pcf % 150 psf See Table Bl o-3 3.0 19.5 113.8 + 5.0 See Table Bl 5-8 14.7 32.2 90.5 + 5.0 See Table Bl 8-12 11.1 36.7 86.9 + 5.7 See Table Bl 2 2.8 26.6 110.4 +18.9 See Table Bl 5 3.8 34.4 93.3 +13.8 *Sample remolded to approximately 90 percent of maximum dry density at near optimum moisture content as determined in accordance with ASTM Test Procedure D1557-70, Method C. B-2 - - - - File No. D-2751-501 June 14, 1982 TABLE B4 Summary County Class III Base Suitability Tests Sample No.: 7-l Depth: 3 - 6 feet Description: Orange-brown, slightly Clayey, Silty, fine to coarse SAND (DEC~~POSRD GRANITICS) - - - - U.S. Standard Sieve l-112" 1" 314" l/2" 318" No. 4 No. 8 No. 16 No. 30 No. 50 No. 100 No. 200 % Finer By Weight 100 99.1 98.2 97.3 97.0 93.4 66.8 42.8 29.0 20.4 14.2 9.6 County of San Diego Class III Base Specifications 100 go-100 50-100 25-55 5-18 "R" Value (ASTM D2844-69) 73 Sand Equivalent (ASTM D2419-74) 42 30 minimum 73 minimum - - - B-3 I-BOR*TOR” N”YBEl SJj37-1628 REPORT OF SOIL TESTS DATE May 28, 1982 >B D*TA: File #1595-l, Job #D-2751-501 S*WLE DATA: Sample submitted - to the laboratory on May 26, 198 1c :cT: Civic Ops. Complex ‘LIE_NT: Geocon. Inc. 9530.Dowdy Drive San Diego, California 92126 - .R-VALYE DATA A 3L .CTOR PRESS - P.S.I. 350 3,ST e COHPACTION .x 10.5 -- z, IT" - IICU. FT. 126.0 ~"#.L"E - STABILOHETER 75 <"D. PRESSURE - PSI. 330 - r, Tn,clr - FEET 0.36 - XPAN. PRESS. TWCK-FEET 0.03 - 7 , T. I. lASSUHED1 - -- B I c I D 350 I I 350 11.0 1 11.4 1 ;;.3 / ;:"3i CLUB. e 300 l?s.l.Ex"o. . 73 2 q ” EXPANSION PRESSURE - - i 47 EO”ILIBRI”” * 73 YI 32”I”ALENT = CPORTED TV (1) G-con, IX. - - - 'mC:cd i BE*a!Nc VALUE It*LIFO.N,* HlGwvA” METnod COMPACTED AND SOAKED FOUR DA”? COMPAcrIc.N J-En: METHOD-CALIFORNI* BEARINO OPTlU”U MOISTUIIE.. 5 OPrlH”M DR” DENSITv.LBS.IC”. n . . PLASTK C”*R*RERl*lt5: l.lP”lD LlYlT PLASTIC LlMlT PLASTlClTl INDEX - -- - - - - - - File No. D-2751-501 June 14, 1982 RECOMMENDED GRADING SPECIFICATIONS 1. General 1.1 1.2 1.3 2. 2.1 2.2 2.3 2.4 These specifications shave been prepared for grading of the Civic Operations Center located on El Camino Real in Carlshad, California. They shall be used only in conjunction with the soil report for the project dated June 14, 1982, prepared bv Geocon, Incorporated. The contractor shall be responsible for placing, spreading, watering, and compacting the fill in strict conformance with these specifica- tions. A qualified soil engineer, hereinafter called the "Soil Engineer," shall act as the owner's representative. All excavations and fill placement should be done under the observation of the Soil Engineer. The soil engineer shall prepare a report upon completion of grading indicating that the subject project has been graded in conformance with the intent of the recommendations presented in the referenced report. ,'Ihe grading should consist of clearing, grubbing, and removing from the site all material the Soil Engineer designates as "unsuitable"; preparing areas to be filled; properly placing and compacting fill materials; and all other work necessary to conform with the lines, grades, and slopes shown on the approved plans. Preparation of Areas to be Graded All trees and shrubs not to be used for landscaping, structures, weeds, and rubbish should be removed from the site prior to commencing any excavating or filling operations. All buried structures (such as tanks, leach lines, and pipes) not designated to remain on the site should be removed, and the resulting depressions should be properly hackfilled and compacted prior to any grading or filling operations. All water wells should he treated in accordance with the requirements of the San Diego County Health Department. The owner shall verify the requirements. All vegetation and soil designated as "unsuitable" by the Soil Engi- neer should be removed under his observation. The exposed surface should then be plowed or scarified to a depth of at least 12 inches until the surface is free from ruts, hummocks, or other uneven fea- tures that would prevent uniform compaction by the equipment used. - - C-l GEOCON - - - - - - - - - - - - - - - - - 2.5 Where the slope ratio of the original ground is steeper than 6.0 horizontal to 1.0 vertical, or where recommended by the Soil Engi- neer, the bank should be benched in accordance with the following illustration. NOTES (1) FINISH GRACE -\oR,,lNAL GRO”ND SOIL ENGINEER (NOTE ,I 1 2.6 3. 3.1 3.2 3.3 3.4 After the areas have been plowed or scarified, the surface should be disced or bladed until they are free from large clods; brought to the proper moisture content by adding water or aerating; and compacted as specified in Section 4 of these specifications. "B" should be 2 feet wider than the com- paction equipment, and should be a min- imum of 10 feet wide. The outside of the bottom key should be below the topsoil or slopewash and least 3 feet InZ dense formational ma- terials. Materials Suitable for Use in Compacted Fill Material that is perishable, spongy, contains organic matter, or is otherwise unsuitable should not be used in compacted fill. Material used for compacted fill should consist of at least 40 percent fines smaller than 3/4-inch diameter. The soil engineer should decide what materials, either imported to the site or excavated from on-site cut areas, are suitable for use in compacted fills; the Soil Engineer should approve any import material before it is delivered to the site. During grading, the contractor may encounter soil types other than those analysed for the soil i"vestigatio". The Soil Engineer should be consulted to evaluate the suitability of such soils. Any material containing rocks or hard lumps greater than 6 inches in diameter should be placed in accordance with Section 6 of these specifications. The Soil Engineer should perform laboratory tests on representative samples of material to be used in compacted fill. Such tests should be performed to evaluate the maximum dry density and moisture content of the samples. The tests should be performed in accordance with accepted test methods of the American Society of Testing and Materials (ASTM). - - c-2 GEOCON - -~ - _- -_ - - 4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7 5. 5.1 5.2 Placing, Spreading, and Compacting Fill Material Unless otherwise specified, fill material should be compacted while at a moisture content near the optimum moisture content and to a relative compaction of at least 90 percent as determined by accepted ASTM test methods. Fill materials should be placed in layers that, when compacted, have a relative compaction in conformance with the project specifications. Each layer should be spread evenly and mixed thoroughly to provide uniformity of materials in each layer. When the moisture content of the fill material is less than that recommended by the Soil Engineer, water should be added until the moisture content is as recommended. When the moisture content of the fill material is more than that recommended by the Soil Engineer, the fill material should be aerated by blading, mixing, or other methods until the moisture content is as recommended. After each layer is placed, nixed, and spread evenly, it should be thoroughly compacted to the recommended minimun relative compaction. The fill should be compacted by sheepsfoot rollers, multiple-wheel pheumatic-tired rollers, or other types of compacting rollers that are capable of compacting the fill at the recommended moisture content. Each layer should be rolled continuously over its entire area until the recommended minimum relative compaction is achieved throughout the fill. The fill operation should be continued in layers, as specified above, until the fill has been brought to the finished slopes and grades shown on the approved plans. Fill slopes should be compacted by sheepsfoot rollers, by track- walking with a dozer, or by other suitable equipment. Compaction operations should continue until the slopes are properly compacted (that is, in-place density tests indicate a relative compaction of at least 90 percent at a horizontal distance of 2 feet from the slope face). Observation of Grading Operations The Soil Engineer should make field observations and perform field and laboratory tests during the filling and compaction operations, so that he can express his opinion whether or not the grading has been performed in substantial compliance with project recommendations. The Soil Engineer should perform in-place density tests in accordance with accepted ASTM test methods; such density tests should be made in the compacted materials below tbe disturbed surface. When results of tests taken within any layer indicate a relative compaction below that recommended, that layer or portion thereof should be reworked until the recommended relative compaction is obtained. c-3 GEOCON - - - - 6. Oversize Rock Placement 6.1 "Oversize" rock is defined as material that is greater than 6 inches and less than 4 feet in maximum dimension. Material over 4 feet in maximum dimension should not be used in fills; such material should be exported from the site, broken into acceptably sized pieces, used for landscaping purposes, or placed in areas designated by the Soil Engineer and/or approved by appropriate governing agencies. 6.2 6.3 - - - - - - - - 6.4 7. 7.1 7.2 The Soil Engineer should continuously observe the placement of over- size rock. Oversize rock should be placed in lifts not exceeding the maximum dimension of the rock, and should be placed in a manner that will not result in "nesting" of the rocks. Voids between rocks should be completely filled with properly compacted (minimum relative com- paction of 90 percent), fine granular material. Oversize rock should not be placed within 5 feet of finish pad grade, within 10 feet of street subgrade, or within 2 feet of the bottom of the proposed utility lines, whichever is deeper. Protection of Work During construction, the contractor should grade the site to provide positive drainage away from structures and to prevent water from ponding adjacent to structures. Water should not be allowed to dam- age adjacent properties or finished work on the site. Positive drainage should be maintained by the contractor until permanent drainage and erosion control facilities are installed in accordance with project plans. No additional grading shall be done, except under the observation of the Soil Engineer. - - .;, c-4 GEOCON