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HomeMy WebLinkAboutCT 73-03; 20 Unit Residential Community; Soils Report; 1972-12-20BENTON ENGINEERING, INC. c7-73-3 APPLIED SOlL MECHANICS ~~ FOUNDATIOHS e 6741 EL CAJON BOULEVARD IAN DIEGO. C*LIFORNI* 92115 PHlLlP “ENKlNG BENTON PREI,I)EhT ClYiL EWGINFLR December 20, 1972 s*Pd DIEGO: 583.5654 LA MESA: 469.5654 Robert D. Miller, Architect 6741 Magnolta Riverside, Calffornia 92502 Gentlemen: This Is to transmit to you two copies of our report of Ptuject No. R-2-26A entitled, “Soils Investigation, 20 Unit Residential Community, West of Ocean Street Between Grand Avenue and Elm Avenue, Carlsbad, California, ” dated December 19, 1972. We are transmitting under separate cover two copies of our report ta Johnsan 8 Nielsen Associates, Consulting Structural Engineers. IF you should have any questions concerning any of the data presented in this report, please contact us. Very truly yours, BENTON ENGINEERING, INC. .-.J A~)f -. i, .I ,c M. V. Pothler, Civil Engineer MVP/pw JAN $ 1913 CITYOF CAXSEAD BuiXng Dcpx:m:;;; ENGINEERING DEPT. LIBRARY City of Carisbad 2075 Las Palmas Drive Cart&a4 CA92009459 ,?li’ ‘, ” SOILS INVESTIGATION 20 Unit Residential Community West of Ocean Street Between Grand Avenue and Elm Avenue Carlsbad, Callfomla For Robert D. Miller Architect Johnson 8 Nielsen Associates Consulting Structural Engineers Proiect No, R-2-26A December 19. 1972 BENTON ENGINEERING. INC. i, :I,‘; :i ,::: .- :*,ir ,.: ., ~: ~,. ~.,.. *HILIP HENKlN.2 BENTOt. PRESIDENT ClVlL ENG,IIEEI BENTON ENGINEERING. INC. APPLIED 501L MECHANICS ~~~ FOUNDATlONS 6741 EL CAJON BOULEVARD *AN DIEGO. CALIFORNIA 92115 s**I DIEGO: 583.5654 LA MESA, 469-565* SOILS INMSTIGATION Introduction This is to present the results of a soils investigation conducted at the site of a proposed 20 Unit Residential Community located westerly of Ocean Street and easterly of the Pacific Ocean between Grand Avenue and Elm Avenue, in Carlsbad, California. The proposed main structures, to be oriented parallel to the beach, will consist of two 3 story wood Frame buildings located on the western portion of the site. In addition, an the Ocean Street side of the site, proposed construction will consist of a smaller 2 story wood Frame building and, on both sides of this, double level parking Facilities with the lower level below street elevation. It is understood that present plans call For raising the elevation of certain portions of she with imported Fill sail. The objectives of the investigation were to dotermine the existing subsurface conditions and physical properties, of the soils in order that recommendations could be presented For the design of an economical and safe Foundation to support structures located on this site. In order to accomplish these objectives, seven borings wem drilled and mpmsentative undisturbed and loose soil samples wem obtained For laboratory testing. At the time of drilling, the site was an ice plant covered area which sloped dawn westerly at a rate of 3.8 Feet horizontal to 1.0 Foot vertical. The diffemnce in elevation between the east property line and the west property line was approximately 37.0 Feet. During drilling operations, the ocean water level was about 8.0 to 10.0 Feet below the existing s&ace along the west property Ilne and was approximately 47.0 to 70.0 Feet away From it. It should be noted that at the time of exploration, the total property contemplated For use included the northernmost end lot adjacent to Grand Avenue. It is our understanding that this lot, having 110 Feet of Frontage on Ocean Street, is no longer to be considered as part of the property limits. This lot is still indicated on revised Drawing No. 1 to show the location of the new property limits in relation to those borings drllled. The Geological Discussion included in this mpart is based on a mconnaissance of the pmviously proposed site which included the northernmost end lot; however, the discussion is still pertinent to the presently proposed site. In addition, some laboratory testing was performed For the previously expected excavation, but this has na bearing on the conclusions and recommendations as stated in this Final report. Finally, it should be understood that a prior report was submitted For the subiect site concerning a pmvlously contemplated development. This report was entitled “Carlsbad Condominiums West of Ocean Street Between Grand Avenue and Elm Avenue, Carisbad, CaliFomia” and was 5 transmitted and dated October 30, 1972. q t? Field investigation Seven borings wem drilled with a truck-mounted rotary bucket-type drill rig at the oppraximate locations shown on the attached revised Drawing No. 1, entitled “Location of Test Borings. ” The borings wem drilled to depths of 25.0 to 54.0 Feet below the existing ground surface. A continuous log of the soils encountemd in the borings was recorded at the time of drilling and is shown in detail on Drawing Nos. 2 to 19, inclusive, each entitled “Summary Sheet. ” Water and driller’s “mud” wem added to all the borings drilled in the caving omas and below water table levels, in order to pmvent the exposed sails From cwing in either From extemoi hydrostatic pressure or From their natural state or dry looseness. Moderate to heavy sloughing and cwing were encountered in all the exploratory borings at various depths, generally within the upper portions. sENTON ENGINEERING. INC The sails worn visually classified by Field identification procedures In accordance with the Unified Soil Classification Chart. A simpliFied description of this classification system is presented in the attached Appendix A at the end of this report. Undisturbed samples worn obtained at Frequent intervals, when, possible, in the soils ahead of the drilling. The drop weight used For driving the sampling tube into the soils was ’ the “Kelly” bar of the drill rig which weighs 1623 pounds, and the weroge drop was 12 inches. The general procedures used in Field sampling am described under “Sampling” in Appendix B. Labomtory Tests Laboratory tests were performed an all undisturbed samples of the soils in order ta deter- mine the dry density, maistum content, and shearing strength. The sails above the water table wem sheared at existing overburden pressures, except in Borings 3 and 5 whem the deeper sails worn sheared under normal loads mduced For a previously proposed depth of 9 Feet of excavation. The soils above the water level wem sheared at existing Field moisture condition and saturated and drained conditions, and those below the water table, were sheamd under saturated and undrained conditions and under normal loo& allowing for submerged densities below the water level. The results of these tests are pmsented on Drawing Nos. 2 to 19, inclusive. Consolidation tests wem performed on repmsentative samples In order to determine the load-settlement character- istics of the soils and the msults of these tests am presented graphically on Drawing Nos. 20 to 30, inclusive, each entitled “Consalldation Curves. ” The general procedures used For the laboratory tests are described briefly in Appendix B. In addition to the above laboratory tests, compaction tests wem performed on same loose soil samples in order to establish compaction criteria. The soils wem tested according to the A.S.T.M. D 1557-66T method of compaction which uses 25 blows of a 10 pound rammer dropping 18 inches on each of 5 layers In a 4 inch diameter l/30 cubic Foot mald. The msults of the tests am pmsented on the Foilowing page. BENTON ENGINELR8NG. INC. :.p :,. i .~ : ,: ,,(: ‘r:ri, ,~C:, L ,,.:, ,,,,, ,..; *:,.. ..,. ~ :,,I in ,.I.,.., ,.:A:,~‘;: ,.,A :‘~ in,,, ...p:’ ; .~.?W .‘“, .,: : .;, -4- Maximum Optimum Mais- Boring Bag Depth Soil Dry Density turn Content No. Sample in Feet Description Ib/cu Ft % dry wt 6 1 1 .O-2.0 Fine sand with slight 125.1 9.1 clay binder, light reddish brown 6 2 4.5-5.5 Fine sand with slight 116.0 12.9 clay binder, light gray 7 1 O-l .o Fine sand, light gray 109.8 15.4 Direct shear tests wem performed on selected loose sail samples mmalded ta 90 percent of maximum dry density that wem all satumted and drained prior to testing. The results of these tests am presented as Follows: Normal Load in kh’w fi Maximum Shear Load kips/sq Ft ~!Za~’ Apparent Friction Cohesion Degmes Wrq fi Boring 6, Bag Sample 1 Depth: 1 .O’-2.0’ 0.5 0.36 42.5 90 1.0 1 .Ol 2.0 1.85 Boring 6, Bag Sample 2 0.5 0.33 37 65 Depth: 4.5’-5.5’ 1.0 0.83 2.0 1.52 Boring 7, Bag Sample 1 0.5 0.37 38 0 Depth: O-l .O’ 1.0 0.71 2.0 1.54 Consolidation tests wum also performed an selected loose soil samples mmolded ta 90 percent of maximum dry density in order ta determine the load settlement characteristics of the compacted soils and the results of the test am presented an Drawing No. 29. Geologic Dlscussion This site including the northernmost end lot next to Grand Avenue consists of apprax- imately 1 .l acres on the beach Front of Carl&ad, California. It is bounded by the PaciFlc Ocean on the west, Ocean Street on the east, and is located behveen the weshvard pm/ections of Gmnd and Elm Avenues. BENTON ENGINEERING. INC The scope of this Geologic Investigation consisted of two study phases - visual site examination and library research. On April 21, 1972, a visual site examination was made and surrounding amas wem inspected ta serve as relative points of reference. Available literatum was searched For data on geology and geologic hazards in the ama, and the logs of our seven borings at this site wem examined to aid in our geologic interpretation. The condominium site is situated on the cwstal plain of northwestern San Diego County. This plain is compased of dissected mesa-like termces and low rolling hills underlain chiefly by nearly Flat lying sedimentary rocks, mainly shale, sandstone and conglomemte. This semi-arid land mcelves about 12 inches of annual rainFall and supports annual grasses and a sparse cover of low brush. Two geologic formations wem Found exposed at the gmund surface. The easterly two thirds OF the site is underlain by Quaternary termce deposits (approximately 1 million years b&m present) which slope gently oceanward. The westerly one third of the site is underlain by Recent beach deposits (approximately 0 ta 10,000 years before present) which am being constantly moved and changed by surf action. Thickness of the Quaternary termce deposits at this location varies From 15 Feet to mom than 27 Feet (see the upper portions of borings 2, 3, 5 and 6 on Drawing Nos. 5, 6, 7, 13, 16 and 17). Thickness of the recent beach deposih varies Fram 10.5 to 11.75 Feet (see the upper portions of Borings 1, 4 and 7 on Drawing Nos. 2, 10 and 18). These younger surface deposits should not be used to support large high-rise buildings, hovmver, these upper stmta may be used to support smaller structums with properly designed Feotings. One t&mation was Found at depth beneath the twa surface fonnations. This formation which underlies the entim site consish of Eocene clayey sandstone with interbeds of sandy and silty clay (appmximately 50 million years before pmsent). This older formation was ancountemd in Boring 1 at 11 Feet, Boring 3 at 15 Feet, boring 4 at 10 Feet, boring 5 at 16.5 feet, Baring 7 BENTON ENGINEERING. INC ):-+< ,, “.’ ,Y?i.j. ,Prj,,::.,:::.~ : .$,, ~, .:; 4 L,: : C~, :<,:, ,, ‘~, .~~~~~-z ,~’ .:,.::; .,. >,,. i ,A/: ~. .,.:_.;.* ,i ,,,,: ,,,, ,-a ,,I ,:._ ~,,~~‘.+y.:i{ .‘y’ee:~ij .~,, ,: ,,,;,; -6- at 10.5 feet, and was not found at all in Borings 2 and 6, which stopped at 25 and 27 Feet, respectively, in Quaternary terrace deposits (see Drawings 2 to 19, inclusive, and Drawing No. 1A). The thickness of this Eocene Formation is at least seveml hundred feet, and lies on even older geologic formations at depth. Southern California lies in a seismically active area and has been placed in seismic risk pmbabiiity zone No. 3. This cormepondr ta the probability of being wb/ected to earthquake intensities of VIII or greater on the MadiFled Mercalii scale, In an area subjected to earthquake induced M.M. scale intensity VIII acceleratians, damage may be anticipated ta be slight in specially designed structures; considemble in ordinary substantial buildings, and gmat in poorly built structures. For M.M. scale intensities greater than VIII, damage may be anticipated ta be correspondlngiy greater. A passable empirical relation between Modified Mercalli intensities and acceiemtion is: Log a =I- l/2, where a is in crq/sec2, and1 is intensity 5 From this relationship it cp1 be found that M.M. saaie VIII cormspondr ta an acceiem- tion of approximately 146 c#sec2. Therefore, it is evident that this portion of Southern Cali- fornia may expect to be subjected ta earthquake caused ground acceleratians of 146 cr+sc2 (appmximately 0.146 g) or mom. The closest large active Fault is the Elsinom, located 25 miles northeasterly, and the most active Large t&tit is the San Jacinto, located 47 miles northeasterly. The clasest maror earthquakes ta the Carl&ad area have occurred to the northeast along the San Jacinta fault and to the northwest along the Newport-lngiewood Fault. A Richter magnitude 6.0 earthquake occurred on the San Jacinta Fault on March 25, 1937, near the town of Anxa, appmximately 50 miles east-no&e& of Carisbod. A Richter magnitude 6.8 .earthqu& occurmd an the San BENTQN ENGINEERING. INC. Jacinto Fault on April 21, 1918, near the town of Hemet, approximately 47 miles north-northeast of Co&ad. And a Richter magnitude 6.3 earthquake occurred on the Newport-lnglewood fault on March 11, 1933, near the town of Newport Reach, approximately 48 miles northwesterly of Carl&ad. By these examples, moderate earthquakes may be anticipated in this ama of Southern California, however, if a proper seismic Factor is used in structural design, then no unusual risk DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS Soil Stmta Soil stmta encountered at Borings 1, 4 and 7 consisted primarily of a I- to compact Fine sandsto depths of 6.5 to 6.8 Feet, immediately underlain by a layer of compact gravelly Fine sand. Beneath this a very firm clayey sand was fovnd with two sepamte interbedded layers of very firm silty clay. Under the lower layer of silty clay the soil varied From very Finn sandy clay, to clayey sand, to silty clay and then ta sandy clay at the depth of explomtion. Medium compact Fine sand FTil soil was found at the location of Borings 2 and 4 to depths of 2.8 and 1.2 Feet, respectively. In Borings 2 and 6 the natuml soil encountered was a fine sand ta the depth of explomtion except for the last 3 feet of Boring 2 when, the sand gmin size changed From Fine ta Rne ta medium. The consistency of these sands was medium compact in the upper stratum changing ta compact For the deeger sands. The upper soils Found in Borings 3 and 5 were primarily interbedded layers of fine and Fine to medium sand, slightly clayey Fine to medium sand, very fine sand and gravelly sand. Beneath 15 feet, very Firm clayey fine ta medium sand, silty clay and sandy clay soils were encauntemd ta the depths of expiomtion. Ground water was encountemd at the time of drilling at the Following depths blow the existing ground surface: Boring 1 - 9.2 Feet1 goring 3 - 11 .O Feet; Boring 4 - 10.0 Feet; Boring 7 - 9.0 Feet. No ground water was encountered in Borings 2, 5 and 6. BENTON ENGINEERING. INC. The revised Drawing No. lA, attached, presents a graphical cross section of the sail prafiies For three sections taken through the site at the locations indicated on Drawing No. I. Conclusions It is concluded From the Field investigation and the results of laboratory testing that the medium compat to compact natural Fine sand Found below 3.0 Feet in Boring 2 and below 2.0 Feet in Borings 4, 6, and 7 and the compact natural fine and Fine to medium sand encountemd below 2.5 Feet in Borings 3 and 5 am suitable For use as load bearing sails. The possibility of a high tide and a moulting saturated soil condition will mquire using values based on a submerged soil condition when designing certain Footings in the western beach Front buildings, in the vicinity of Borings 4 and 7. In addition, the possible hiah tide condition will require erosion control in the area of the sail covering the Footing line on the west side of the beach Front buildings. The level of thegewatar some amos of the proposed site will limit the depth at which the Footings can be placed. The excavations For Footings am recommended ta be sloped back an a slope ratio of 1 2 horizontal to 1 Foot vertical or Flattqr, ta prevent excessive sloughing into open excavations, I All clean Fill materials and loose natural soils should be removed and recompacted prior to placing additional compacted Fill and/or pouring concmte slabs. All organic materials and dirty Fill should be mmoved and wasted off the site. Recommendations Foundation Support For Footings Located in Natuml Soils Two Level Parking Facllitles It is mcommended that the Footing along the eastern side of these Facilities be placed at a minimum depth of 4 feet below the existing ground surface with the bottom of the Footing BENTON ENGINEERING. INL- ,,,~ ,,,.-i~,;,--C,:‘~;... ,_, ;;i,i,;.:,~l. ,,ji ,,,, i,, ,,,, I;;i i. ;>,, j_ :, -9- located ot least 1 foot into the natural medium compact to compact load bearing soils. One foot ‘wide continuous footings so located Into the recommended load bearing soils moy be designed for an allowable bearing value of 825 pounds per square foot. For each additional foot increase of footing depth, as measured from the lowest adjacent final sol1 l levotlon, this value may be Increased by 560 pounds per square foot. For each addltional foot Increase of footing wldth, this value may be increased by 265 pounds per square foot. The maximum bearing value mcommended, considering all increase allowances for Increased depth and/or width, is 2500 pounds per square foot. These bearing values am for dead plus live loads and may be increased by one-third for combined dead, live and seismic loads. The settlement of a 2 feet wide continuous footing in this area placed at a depth of 4 feet below the adjacent ground surface and loaded to 2.0 kips per lineal foot is estimated to be less than 3/16 inch. Residential Units Eastern Footing Line - It is mcommended that the foundatlons along the eastern side of these buildings be placed at o minimum depth of 3.5 feet below the existing noturol ground surface with the bottom of the footing located at least I. 0 feet into the natural compact load bearing soils. One foot wide continuous footings so located into the recommended load bearing soil may be deslgned for on allowable bearing value of 1365 pounds per square foot. For each additional foot increase of footing depth, as measured from the lowest adiacent final soil elevvotlon, this value may be increased by 320 pounds per squam foot. For each additional foot increase of footlng width, this value may be incmased by 130 pounds per square foot. The maximum bearing value recommended, considering all increase allowances for increased depth and/or width, is 2500 Founds per squam foot. These bearing values are for dead plus live loods and may be incmased by one-third for combined deod, live ond seismic loads. BENTON ENGINEERING. INC. 1: ,;;,::: :.:‘...,‘,,%,, .,,t,~~;;>~: ~: : i ., -lO- The settlement of a 2.5 feet wide continuous footing in this area placed ot a depth of 3.5 feet below the adjacent ground surface and looded to 4 kips per Ilneol foot is estimated to be less than i/4 inch. Western Footlng Line - It is recommended that the foundations along the western side of these buildings be placed at a minimum depth of 3 feet below the existing natural ground surface with the bottom of the footing ot least 1 foot into the noturol medium compact load bearing soils. One foot wide continuous footings so located Into the recommended load bearing soils may be designed for on allowable bearing value of 400 pounds per square foot assuming submerged conditions after construction. For each additional foot increase of footing depth, as measured from the lowest adjacent soil elevation, this volue may be increased by 270 pounds per square foot. For each additional increase In footing width, this value may be increased by 125 pounds per square foot. The maximum bearing value recommended, considering all increase allowances for increased depth and/or width, is 1500 pounds per square foot. Also, these footings should be located no deeper than 5 feet below the existing ground surface or above an elevation equal to the elevation of the ground water plus the width of the Footing which ever is the shallower depth. These bearing values am for dead load only and may be increased by one-third for combined deod, live and seismic loads. The settlement of a 4 feet wide continuous footing placed at o depth of 4.0 feet below the adjacent ground surface and loaded to 4 klps per lineal foot is estimated to be less than l/8 inch. Retaining Walls - It is recommended that the ratalning walls to be located adiocent to the eostern side of the residential units be designed using the same allowable bearing values os mcommended for the eastern footing line of those buildings. BENTON ENGINEERINO. INC. ::‘i, ,, ‘~;r;+::‘*,;,~; ‘, ,. ,:~~ ,,., :;.;<#,i:,i:‘;, I:‘,~ .,,,,,: -ii ;, ,, ~~ :, ,, ; ,~ ,, ,F,‘...:, ~,j ,(./ -.*.~;f’..,~ ;ir*, ,<.; ,,i .,., ,‘. ,~ -ll- Slab Support Concrete slobs may be poured directly onto thr medium compact and compact notural fine and fine to medium sand soils. Concrete for floor slobs may also be poured on compacted filled ground where the fill is uniformly compacted at optimum moisture content to at least 90 percent of maximum dry density In accordonce wlth A.S.T.M. Test Method D 1557-70. Foundation Support For Footings Located In Compacted Fill The foundations for part or all of those structures located generally on the eastern half of the site may be supported by inported fill soil so long as this soil is suitable and properly placed. Fill employed OS structural support for foundations should meet the following speclflcatlons: a) It shall be a silty, clayey sand or sand soil type. b) It shall have no more than 40 percent posslng the No. 200 sieve size. Also, at least 50 percent shall pars the No. 4 sieve and it shall contain no grovel larger than 3 inches in diameter. 4 The expansion of a one inch high sample of the minus No. 10 material remolded to 95 percent of maximum dry density and then air dried for two days at 105“ F, then loaded to 500 pounds per square foot and saturated, shall not exceed 0.5 percent. 4 The soil when compacted to at Ieost 90 percent or greater of maximum dry density shall have an allowable bearing value of not less than 1000 pounds per square foot for footings placed 1 foot below the lowrst adiacent finbl compacted ground surface. This additional fill should be placed and compacted in accordance with the attached Appendix AA, “Standard Specifications For Placement Of Compacted Filled Ground” as modified in the preceding paragraphsu Allowable bearing value recommendations for footings placed in the imported fill will be provided when a suitoble Import soil is selected and can then be tested. In addition, when a structure Is to be supported by both fill and natuml soils, the settlement charocterlstfcs of the fill BENTON ENGINEERING. INC will be determined to see If they ore commensurate with those of the natural soil. These recommendotlons will then become o port of this final report. Footing Excavation Due to the general lock of cohesion and the overoll low moisture content in the upper sand soils, it is mcommended thot, in order to keep caving and sloughing to a minlmum, the slopes for the excovotion of footings be ot a slope rotio of 1 horizontol to 1 vertlcol or flatter. This slope rotio should allow the top of slope for excovotlon of the continuous footing on the eost side of the two level parking facilities odiocent to Ocean Street to remoln within the eastern property boundory Ilne. Core should be token to insure thot no surcharge loods ore placed on or neor the top of these slopes in order to preclude unnecessary coving or sloughing. It is recommended that all footlngs be inspected to verify that depth of excwation will place the footlng at the proper depth Into the lood bearing soils, that these have been excavated to the correct dimensions and that the excavations ore clean of cdl disturbed soils prior to place- ment of relnforcing steel and concrete. Pressures Against Retaining Walls Where retaining walls om pmposed for construction against the existing notural soils, the walls moy be desigr#d to resist on active lateral pressure equlvolent to thot developed by a fluid with a donrity of 38 pounds per cubic foot. These values assume o level surface behind the walls without superimposed surcharge loads and a non-satumtod soil condition. If surcharge loads ore added to the level retained soil, then the unit active pressures should be Increased os mqulred. In odditlon, if the retoinlng walls ore not constructed with weep holes to allow drainage then surface water should be controlled to be kept from rdumting the soil behind the walls. If this is not feasible, then perforated pipe ond pea grovel should be placed at the base of ond behind the walls to allow drolnoge out from behind ond to other controlled drainage systems. If imported clean sand or silty sand is used as compacted fill behind retaining walls, BENTON ENGINEERING. INC. the walls moy be designed to resist on active loteral pressure equivalent to that developed by o fluld with a density of 30 pounds per cubic foot when the fill is compacted at optimum moisture content to 90 percent of maximum dry density bored on A.S.T. M. Test Method D 1557-70. Loteral Resistonce Lateral forces exerted on the structures by wind and siesmic forces moy be resisted by sliding friction on the bottom of the foundation and/or by passive pressures developed by the soils. The sofe passive resistonce on the side of footings cost against the natural soils may be assumed to be equal to thot developed by o fluid with densities OS follows: In the oreo of the eastern footing line of the residential units, 80 pounds per cubic foot and in the orea of the western footing line of the msidential units, 48 pounds per cubic foot. For friction on the bottom of the foundations, a coefficient of 0.4 is recommended for the frictional resistance between ad + soil and the concrete. Erosion Control With the pouibilitv of hiah tide conditions, the soil cover over the western footing line of the residential units should be protected from eroding wave action which could transport the soil over these footings mvoy and consequently decrease the soil boring value. One possible protective construction method is to place riprafon the surface of the bockfill soil on the ocean side of this outer footing line. To prevent underminlngr a 1 foot minimum layer thickness ofu gw (moxtmum size 2 l/2 inch diameter) should be embedded between the riorap and the hoc * yl_loil to act os a filter layer. The riprop layer should extend out from the footing line o minimum horizontal distance of 10 feet. This protective materiol can then be covamd with sand or sodded and planted, if so desired. Depending on the expected occurmnce mte of the high tide condition ond the severity of the wove action, additional protective construction could be Installed. Another possible BENTON ENGINEERING. INC. method is embedding either timbers or precast concrete sheet pile sections vertically into the beach, leaving 2 to 3 feet above ground, and backfilling with beach sand to provide a small seawali structure and assist in breaking the wave action and thus reduce the eroding forces. Respectfully submitted, BENTON ENGINEERING, INC. By-&L@L y‘ G;;,,, thier, Civil Engineer Distrr (2) Robert D. Miller, Architect Attention: Mr, Hardy Lewis (2) Johnson & Nielsen Consulting Structuml Engineers Attontion: Mr. Per Ron DF l&VP/pm BENTON ENGINEERING. INC. SUMMARY SHEET BORlNO NO. 1 ELiVATlON 49.0’ l . ---- Gray, Moist, Medium 1.6 3.0 05.9 0.33 0.4 Gray with Light Groy, Gray and Light Gmy, Moist, Compoct, Bits of Shells, 40 to 50 Percent Gravel and Cobbles to 6 inches Light Gmy, Sotutoted, Very Firm, Layers with Coarse Sand Grains, Layers with Gravel Indicates undisturbed drlvo ramp10 indicates loose bag somple Indicator undisturbed drlvo sample - mplo net retained tothetackandtagi 2.0 feet above existi round surface In the atum = E Ievation 68. ,_ ..,,, ~., ..; ,..,, ~,I :,:, ,, ,,. ,~, ;~ L z > “6 t YE FA 522 SUMMARY SHEET :* g= gk ? $; $ $3 k -2 OE:5 BORING NO. 1 (Cont.) ;z it&>, ig & “@ YY > >a gig 4 16” . ..“... zt “pz a E’ ZY Light Gray, Saturated, Very Finn, Layors wth Coorse Sand Groins, Layon with CLAYEY FINE Grovel to 1 Inch TO MEDIUM SAND Light Gray, Saturated, Very Finn, Layers with Coarse Sand Groins, Layers with Grovel to 1 Inch DRAWING NO. BENTON ENGINEERING, INC. 3 ,:“~.y,m:J- .:i;‘ig*~ II,‘i-,,?X /, ~., ,., ,,,: ,,,, ~-:,:‘: y:;‘~-<~.;,, ,; ‘,: ,; ~: SUMMARY SHEET BORING NO. 1 (cent .) . . I I z I Light Gmy, Sotumted, Vary Fim, with Very Fine ta Fitm Sand SILTY CLAY 19.2 - ‘1.5 i.44 ; 1 . c - - - FINE SANDY CLAY 26.4 ‘.50 i.76 -+ - - El Light Gray, Soturotcd, Vary Finn I CLAYEY FINE TO MEDIUM SAND 21.t SILTY CLAY - - 2, 53.8 .29 FINE SANDY CLAY - - L -- PROJECT NO. 72-2-26A ~~~-1 ORAWNG NO. BENTON ENGINEERING, INC. 4 1 1 1 1 1 1 1 1 1 1 : : SUMMARY SHEET BORlNG NO. 2 ELEVATION 97.0’ P.C. Concrete to 2 Inches i:-.-*, :i: J’~‘i~ ;‘.:‘: ,‘, : 7 : i c! : : i , 1: I L ?I$ g f 2;: SUMMARY SHEET gg Kg: 5 k fJ?z 8% BORING NO. 2 (Cont.) : 21 2 ,l’,i:j;;jj:i Light Gmy, Dry, Firm, :,.:_... FINE SAND 22- :;:).:;.:;;,I. Slightly Micaceous MEDIUM BENTON ENGINEERING, INC. y*, v,; .,.~,, “. ~, ,:, ,- ., _ ._,,, ,, ,: %, .~:‘.s :, ~_ ,,. ./I~,, ~ ,,, >,,_.,” ‘<,‘,.,$ .~~ ~4 : SUMMARY SHEET BORING NO. 3 ELEVATION 9.7 2.2 98.1 0.41 0.21 WITH LAYERS OF VERY FINE TO FINE SAND AND VERY FINE TO ompact, Very Micaceovs, 40 to 50 Percent Gravel and 16.2 12.3 118.6 1.7T 22.7 12.6illE.O 2.23* Continued on Draw BENTON ENGINEERING, INC. i:r:‘~i)~i-~.:-::::: T .,. ?; 7~::. ‘_.:-r .’ ~‘~s ~-7: : ,, -. . . . . . . . . . __ Light Gmy, Slightly Moist, 22 - Very Firm, With 1 l/2 Inch IIZZI Layers of 40 to 50 Percent 23 Gmvol to 1 Inch, Layers With Medium tu Coarse Sand 37- 38- 39- :I0 :LAYEY FINE TO MEDIUM SAND 16.6 4.5 2.5 - :: 12; %; 52 - 3.r l.E 4.5 1 .5 - 18 I6 16 !4, - .8 !.X i.l( i.3c i.12 II I Continued on Dmwing No. 9 PROJECT NO. DRAWING NO. 72-2-26A BENTON ENGINEERING, INC. 8 i n. .: ,i~ ,>a-?..,:~ ;_ ,;, ?,. ;, ,, :5- . . ~. ,.: _‘. Y., iii $~‘:c,, \ > ;?: “.:,&(;~,,f<.$; ‘-$,.:,:, i, >: SUMMARY SHEET BORING NO. 3 (Cont.) l Indicates samples were sheared under nermal loads reduced for 9 frt of l xcavd I z, t SUMMARY SHEET =t a!; z BORING NO. 4 ;iJ luy d!$ zt ELEVATION 67.0’ ;i LSO I% 2 aa “$ gj 0 I 2,” 3 Inch Layer of Organic FINE SAND FIL 1.6 2.6 98.5 0.34 0.5 FINE SAND 1.6 4.2 92.3 0.52 0.4 7 Gmy, Moist, Compact, 40 to 1 8 9 IO I.?. 50 Percent Gravel and )kz$$>; CZhZF to 6 Inches, Bits of GRAVELLY FINE SAND CLAYEY FINE T( MEDIUM SAND 16.2 1.1 - - 13.0 - - - 27.6~-15.~ 16.P1.75 Light Gray, Moist, Very Firm, 19.5 12.2 120.0 4.05 With Fine Sand, Lenses of Clayey Fine to Medium Sand CII TV ,-I AV II I Continued on Drawing No. 11 i I I PROJECT NO. DRAWING NO. 72-2-26A BENTON ENGINEERING, INC. 10 . __. <,‘tm~,~’ ,~ .,,. i. in. ,c_ ), “‘ ‘:.,dI-.?;,rl.‘r,,, ,,,, ,:,.,, 1,,~ l;s, i “>,Z& .,, . ,,* ,::‘~:T, /_ .,J”,.~ ,_;yi II _“.., ~?j ,~_(; SUMMARY SHEET GORING NO.-.) PROJECT NO. DRAWING NO. ,” Sji.,,‘.~,~,. ,.~,,r..:,:, :e. ,_, ,,, ‘7<,, ~. ,,T.. -,.i,,,:,: ,e; . I, ,I. 1, ~, “., : ;. * _.. ..~ SUMMARY SHEET BORING NO. 4 (c&.) 72-2-26A I BENTON ENGINEERING, INC. I 12 SUMMARY SHEET BORING NO. 5 ELEVATlON 79.0’ Very Firm, Slightly Cenmn’ted, Lenses of Fine to Medium ALTERNATING VERY FINE TO FINE TO MEDIUM BENTON ENGINEERING, INC. SUMMARY SHEET BORING NO.-*) 2 Inch Layers of Fine to Medium Sandy Clay, Patches l Indicates samples were sheared under normal loads reduced for 9.0 feet of excaw BENTON ENGINEERING, INC. 14 Ion. ;:: p’.: ,A:.~ ;L? .‘c.‘.p ,~’ ,.: ,_i:,?;~ . ,~, ,: SUMMARY SHEET BORING NO. 5 (Cont.) FINE TO MEDIU SANDY CLAY Brown Stains Along Fractures l Indicates samples wwu sheared under normal hods reduced for 9.0 foot of ~XC(IY< DRAWING NO. on. ~,:.~, ~. ;~ ‘),i..;‘:, ‘.!, _‘ ,,:.~ :ij+*, j. -i,w& ;_j,ivl,i .I; .,., ~.- .,‘>< ,.(~,l~, _ ,1 BORING NO. rj ELEVATION 97 .O’ PROJECT NO. DRAWING NO. 72-2-26A BENTON ENGINEERING, INC. I 16 SUMMARY SHEET BOR,NG NO. 6 (Cpnt.) FINE SAND ,.,:-:::.: !5- ..:: _... . . . . ..‘,.,. ;..:y::.,: 39.0 20.7 100.3 3.62 PROJECT NO. DRAWING NO. ~, 72-2-26A BENTON ENGINEERING, INC. 17 j 76 Am [~ii,ii,-.i:::,. [ Light Gmy and Gmy, Dry, Loose Slighhy Moist, Medium : .‘. : : ;; :: : ‘. .‘.‘. ::.. I: ; . . ;:: ._: .,. . :;. : :‘: . Light Gmy and Gray, Slightly Molst, Compact, Some Medium Gmlns, 40 to 50 Percent Gravel and to 6 Inches, Bits of 16.2 - 89.’ 96.8 FINE SAND GRAVELLY FINE SAND 8 CLAYEY FINE TO MEDIUM SAND -w 16- l7- +j I SILTY CLAY Light Gray, Moist, Very Firm Light Gray, Slightly Moist, Very Firm, Layers With Medium to Coarse Grains l8- CLAYEY :INETODMEDIU/ IO.8 13.2 21-. Continued an Dmwitq No. 19 I PROJECT NO. DRAWING NO. 72-2-26A BENTON ENGINEERING, INC. 18 : i 7 ; : 4 0 ? ; i (1 I 28 29 SUMMARY SHEET BORING NO. 7 (Cont.) 30 . . . . . 51 f.1;;: El . . . . .^ I u-j [ii::” : : f l/2 inch Lenses of Silty Clay $3 .‘. w .‘. ta I -I /-, 1::; .:.~.,,:,I Light Gmy, Moist, Very Firm 1 \ y(@ :.: :.~.. l8-l 7 i PROJECT NO. 72-2-26~ CLAYEY :lNE TO MEDIUM SAND 60.C FINE SANDY CLAYEY FINE TO MEDIUM /ERY FINE TO :INE SANDY SILTY CLAY /ERY FINE TO 10.5 j124.C I ,. , BENTON ENGINEERING, INC. 3.80 6.19 DRAwiNG NO. j ! 19 I CONSOLIDATION CURVES LOAD IN KIPS PER SPUARE FOOT @f 0.4 0.6 0.6 1.0 2 4 6 8 IO 16 I I I I I I I I I I I I I I Rn.:nn 1 0 G& I1 1 -o--..- ,, Depth 2’ -* ) L 0 INDICATES PERCENT CONSOLIDATION AT FIELD YO,ST”RE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. DRAWlNO NO. 72-2-26A I BENTON ENGINEERING, INC. I 20 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FDDT 0.6 0.6 1.0 2 4 6 3 4 2 =5 5 ; I- +4 !Ls 5 ;f +3 Z 0 0 F 2 i % I f! 2 I I //I I /Ill 0 INDICATES PERCENT CONSOLIDATION AT FIELD LlD,ST”RE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 72-2-26A I BENTON ENGINEERING, INC. I DRAWlNO NO. 21 ; ( : : : . c : : CONSOLIDATION CURVES LOAD IN KIPS PER SOUARE FOOT I?& 0.4 0.6 0.6 1.0 2 4 6 6 I I IIIII I I I I Borina? 4 :: i 5 f 6 2 i I 7 2 8 t : % 9 F 10 a i 8 0 ; 1 2 3 0 INDICATES PERCENT CONSOLIDATION AT FIELD YOlSTURE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 72-2-26A I BENTON ENGINEERING, INC. I DRAWINQ NO. 22 ! :q ,$ z” I1 k 2 2 : k3 CONSOLIDATION CURVES LOAD IN NIPS PER OQUARL FOOT .- 0 INDICATES PERCENT CONSOLIDATION AT FIELD MOlSTURE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 72-2-26A DRAWINS NO. BENTON ENGlNEERlNG, INC. 23 ,,,_ ‘,,( ‘~1 : ‘i, ,, ‘.,~ :, .~,. :,, 1, ‘~ ,,i ,~, .: ~; ,;,: ‘. ‘/, ., .+.. I ~I :,,~ :~:~ .~, ~. : ,,, CONSOLIDATION CURVES LOAD IN KIPS PER SPUARE FOOT oQZ 0.4 0.6 0.6 1.0 2 4 6 8 10 I6 1 I I I 1 B--!-- 9 1 2 3 0 ti = z 1 z 2 !I 0 PROJECT NO. 72-2-26A Cl INDICATES PERCENT CONSOLIDATION AT FIELD YO,STURE . INDICATES PERCENT CONSOLIDATION AFTER SAtURATION DRAWINS NO. BENTON ENGINEERING, INC. 24 ~,,, ~:,;,;,!) j A~; ,) ,, .,.. 3 ! I (I , I ( 7 ., , 0 : i : I : (1 I CONSOLIDATION CURVES LOAD IN KIP5 PER SPUARE FOOT 0.4 0.6 0.6 1.0 2 4 6 4 -- -- 1 a= n,...*l. 12’ z z ; 5 ; 5 u u z z i-1 i-1 !i !i % % b: 0 b: 0 k k 1 1 I I F’-- A PROJECT NO. 72-2-26A 0 INDICATES PERCENT CON50LtDATION AT FIELD YOlSTURE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION DRAWIN NO. BENTON ENGINEERING, INC. 25 ,A,,“, :, ;, ,: i:,,a.c .jl;gyj ?L.‘i’y:,i+* ~l~,j:,;b”‘~:i’ ,;,,. ,~ C!.,,~/~ ., ,, ‘, 4 2 w z O 0 E 1 Ll % 12 k 3 5 iii % 4 :5 E ? 26 3 7 CONSOLIDATION CURVES LOAD IN KIPS PER SOUARE FOOT ..a AZ ,.a I,l I) _ . e e .^ 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,...... . . . . . . . . . . . . . . . . . . . . . . ,I, ,,,,.,.,./.,.,,,.,.,.,.,.,,,,,,,.,.,, .,.,.,.,;,.,.,., I./.,: ,./.,.,. .,j,., ,.,.,.,.,.,.,. Bori 5 - -4\ Samp e 7 “c1 Depth 21’ - k, ., _ .h 0 INDICATES PERCENT CONSOLIDATION AT FIELD YOlSTURE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 72-2-26A I BENTON ENGINEERING, INC. I DRAWIN@ NO. 26 _, ,,,,,, ~:~ .‘,,,, CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT 3- ‘\ 4- \, ‘Ir, :: .L \ = E 5 --------- E 0 INDICATE5 PERCENT CONSOLIDATION AT FIELD LlOlSTURE . IND1CATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 72-2-26A I BENTON ENGlNEERlNG , INC. I DRAWINQ NO. 27 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT I I - -, - ,-. -. - D.6 1 i -~: t I 2 4 6 IO ( &ring 6 16 I I lIII~?o14 I 0 INDICATES PERCENT CONSOLIDATION AT FIELD YOlSTURE . INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. DRAWlNO NO. i2-2-26A BENTON ENGINEERING, INC. 28 .? I I l 7 : 4 E : : , 1 c I 1 2 3 4 2 r5 ..,... 0 .,.... z ::.... 0 !tl : S1 ~ CONSOLIDATION CURVES LOAD IN KIPS PER SOUARE FOOT PROJECT NO. 72-2-26A ueprn: ” ro I Remolded to 90% - ---t--+ -.,-.- --_ 0 INDICATES PERCENT CONSOLIDATION AT FIELD MOISTURE . INDICATES PERCENT CON6OLlOATlON AFTER SATURATION DRAWlNO NO. BENTON ENGINEERING, INC. 29 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT Is?3 1 0.4 0.6 0.0 I.0 2 4 6 6 IO I6 !:qe’2 Depth 4’ E 0 0 c’ 1 !3 % a 2 I I I I I bin 7 Samp e 9 9 0 INDICATE5 PERCENT CONSOLIDATION AT FIELD YO,STURE . INDICATES PERCENT CONSOLlDATlON AFTER SATURATION PROJECT NO. 72-2-26A I BENTON ENGINEERING, INC. BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS - FOVNDATIONS 67.1 EL CAJON BOVLEVARD SAN DIEGO. CALIFORNIA eza15 P”lLlPHo4KING BENTON .“ISIDIHT ClVlL LNT,NTL” SAN DIEGO: 5as-5.ss4 I.* Mrs*: 4e*.s.ss. APPENDIX AA STANDARD SPECIFICATIONS FOR PLACEMENT OF COMPACTED FILLED GROUND 1. General Description. The objective is to obtain uniformity and adequate internal strength in filled ground by proven engineering procedures and tesk so that the proposed structures may be safely supported. The procedures include the clearing and grubbing, removal of existing structures, preparation of land to be filled, filling of the land, the spreading, and compaction of the filled areas to conform with the lines, grades, and slopes as shown on the accepted plans. The owner shall employ a qualified soils engineer to inspect and test the filled ground as placed to verify the uniformity of compaction of filled ground to the specified 90 percent of maximum dry density. The soils engineer shall advise the owner and grading contractor immediately if any unsatisfactory conditions are observed to exist and shall have the authority to reject the compacted filled ground until such time that corrective measures are taken necessary to comply with the specifications. It shall be the sole responsiblllty of the grading contractor to achieve the specified degree of compaction. 2. Clearing, Grubbing, and Preparing Areas to be Filled. (a) All brush, vegetation and any rubbish shall be removed, piled, and burned or other- wise disposed of so as to leave the areas to be filled free of vegetation and debris. Any soft, swampy or otherwise unsuitable areas shall be corrected by draining or removal, or both . (b) The natural ground which is determined to be satisfactory for the support of the filled ground shall then be plowed or scarified to a depth of at least six inches (6’7, and until the surface is free from ruts, hummocks, or other uneven features which would tend to prevent uniform compaction by the equipment to be used. c=) Where fills are made on hillsides or exposed slope areas, greater than 10 percent, horizontal benches shall be cut into firm undisturbed natural ground in order to pro- vide both lateral and vertical stability. This Is to provide a horizontal base so that each layer is placed and compacted on a horizontal plane. The initial bench at the toe of the fill shall be at least 10 feet in width on firm undisturbed natural ground at the elevation of the toe stake placed at the natural angle of repose or design slope. The soils engineer shall determine the width and frequency of all succeeding benches which will vary with the soil conditions and the steepness of slope. APPENDIX AA (4 -2- After the natural ground has been prepared, it shall then be brought to the proper mois- ture content and compacted to not less than ninety percent of maximum density in accordance with A.S.T.M. D-1557-66T method that uses 25 blows of a 10 pound hammer falling from 18 inches on each of 5 layers in a 4” diameter cylindrical mold of a 1/30th cubic foot volume. 3. Materials and Special Requirements. The fill soils shall consist of select materials so graded &at at least 40 oercent of the material oasses a No. 4 sieve. This mav be obtained from the excavation of banks, borrow pits of any other approved sources and by mixing soils from one or more sources. The material uses shall be free from vegetable matter, and other de- leterious substances, and shall not contain rocks or lumps of greater than 6 inches in diameter. If excessive vegetation, rocks, or soils with inadequate strength or other unacceptable physical characteristics are encountered, these shall be disposed of in waste areas as shown on the plans or as directed by the soils engineer. If during grading operations, soils not encountered and tested in the preliminary investigation are found, tests on these soils shall be performed to determine their physical characteristics. Any special treatment recommended in the preliminary or subsequent soil reports not covered herein shall become an addendum to these specifications. The testing and specifications for the compaction of subgrade,subbase, and base ,materials for roads, streets, highways, or other public property or righk-of-way shall be in accordance with those of the governmental agency havirg jurisdiction. 4. Placing, Spreading, and Compacting Fill Materials. (b) Cc) (4 The suitable fill material shall be placed in layers which, when compacted shall not exceed six inches (6”). Each layer shall be spread evenly and shall be throughly mixed during the spreading to insure uniformity of material and moisture in each layer. When the moisture content of the fill material is below that specified by the soils engineer, water shall be added until the moisture content is near optimum as specified by the soils engineer to assure thorough bonding during the compacting process. When the moisture content of the fill material is above that specified by the soils engineer, the fill material shall be aerated by blading and scarifying or other satis- factory methods until the moisture content is near optimum as specified by the soils engineer. After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to not less than ninety percent of maximum density in accordance with A.S.T.M. D-1557-66T modified as described in 2 (d) above. Compaction shall be accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other approved types of compaction equipment, such as vibratory equipment that is specially designed for certain soil types. Rollers shall be of such design that they will be able APPENDIX AA -3- to compact the ffll material to the speclfled density. Rolling shall be accomplished while the fill material is at the specified moisture content. Rolllrg of each layer shall be continuous over lk entire area and the roller shall make sufficient trips to insure that the desired density has been obtained. The entire areas to be fllled shall be compacted. (e) Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compacting operations shall be continued until the slopes are stable but not too dense for plantlw and until there is no appreciable amount of loose soil on the slopes. Compacting of the slopes shall be accomplished by backrollirg the slopes In Increments of 3 to 5 feet in elevation gain or by other methods producing satisfactory resutk. Field density tests shall be taken by the soils engineer for approximately each foot in elevation gain after compaction, but not to exceed two feet in vertical height between tests. Field density tests may be taken at intervals of 6 inches in elevation gain If required by the soils erglneer , The locatlon of the tests in plan shall be so spaced to give the best possible coverage and shall be taken no farther apart than 100 feet. Tesk shall be taken on corner and terrace lok for each two feet In elevation gain. The soils ewgfneer may take addltional tests as considered necessary to check on the uniformity of compac Hon. Where sheepsfoot rollers are used, the tesk shall be taken In the com- pacted material below the disturbed surface. No addi tlonal layers of fill shall be spread until the ffeld density tests indicate that the specified density has been obtalned. (g) The fill operation shall be continued In SIX Inch (6”) compacted layers, as specifTed above, until the fill has been brought to the flnlshed slopes and grades as shown on the accepted plans, 5. lnspectlon. Sufficient Inspection by the solls ergineer.shall be maintalned durlflg the fllli~ and compactlrg operations so that he can certify that the fill was constructed in accordonce with the accepted specifications. 6. Seasonal Limits. No fill material shall be placed, spread, or rolled lf weather conditions Increase the moisture content above permissible limits. When the work IS Interrupted by rain, fill operations shall not be resumed until field tests by the soils erglneer lndlcate that the moisture content and density of the fill are as previously specified. 7. Limitfw Values of Nonexpansive Soils. Those soils that expand 2.5 percent or less from air dry to saturatfon under a unit load of 500 pounds per square foot are considered to be nonexpansive. 8. All recommendations presented in the “Conclusions” section of the attached report are a part of these specitlcatIons. PCYI”nl .YlmYl!L”llm~ INC. BENTON ENGINEERING. INC. APPLIEO SOIL UECHlNlCS -~~ FO”NDAT,ONS (17.1 EL CAJON llOULE”ARD 51N DlEGO. CALIFORNIA *21,, APPENDIX A Unified Soil Classification Chart* SOIL DESCRIPTION GROUP SYMBOL I. COARSE GRAINED, More than half of materral IS larger than No. 200 sieve size.** - GRAVELS CLEAN GRAVELS s half of coarse fraction is larger than No. 4 sieve size but smallerGRAVELS WITH FINES thon 3 inches (Appreciable amount of fines) SANDS CLEAN SANDS -than half of coarse fraction is smaller than No. 4 sieve size SANDS WITH FINES (Appreciable amount of fines) II. FINE GRAINED, Mae than half of materiblisr than No. 200 sieve sire.** SILTS AND CLAYS Liquid Limit Less than 50 SILTS AND CLAYS Liquid Limit Greater than 50 Ill. HIGHLY ORGANIC SOILS GW GP GM GC Well graded gravels, gravel-sand mixtures, little a no fines. Poorly graded gravels, gravel-sand mixtures, little or no fines. Silty gravels, poorly graded gravel- sand-silt mixtures. Clayey gravels, poorly graded gravel- sand-clay mixtures. SW SP SM SC Well graded sand, gravelly sands, little or no fines. Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly groded sand-silt mixtures. Clayey sands, poorly graded sand-clay mixtures. ML CL OL MH CH OH Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plasticity. lncrgonic clays of low to medium plas- ticity, gravelly cloys, sandy cloys, silty cloys, lean cloys. Organic silts and organic silty-cloys of low plasticity. Inorganic silts, micaceous cr diatama- ceous fine sandy or silty soils, elastic silts. lnagonic clays of high plasticity, fat clays. Organic clays of medium to high plasticity. PT Peat and other highly organic soils. TYPICAL NAMES 8.N D1100: ~,I-,*~. LA YE**: 46#-S6S. * Adcpted by the Carps of Engineers and Bureau of Reclamation in January, 1952. ** .I, -: -.._ .?--. - +I.:. ,k”& “,.a I I t Clnnrlnrrl. BENToN ENGINEERING. INC. APPLIED SOlL MECHANICS FOUNDATIONS 6741 EL CAJON BOULEVARD SAN OIEGO. CALIFORNIA 92115 P”ILIP HENKING BENTON PICS,OLf,T ClYlL LUGINESE APPENDIX B Sampling The undisturbed soil samples are obtained by forcing a special sampling tube into the undisturbed soils at the bottom of the boring, at frequent intervals below the ground surface. The sampling tube consists of a steel barrel 3.0 inches outside diameter, with a special cut- ting tip on one end and a double ball valve on the other, and with a lining of twelve thin brass rings, each one inch long by 2.42 inches inside diameter. The sampler, connected to a twelve inch long waste barrel, is either pushed or driven approximately 18 inches into the soil and a six inch section of the center portion of the sample is taken for laboratory tests, the soil being still confined in the brass rings, after extraction from the sampler tube. The samples are taken to the laboratory in close fitting waterproof containers in order to retain the field mois- ture until completion of the tests. The driving energy is calculated as the average energy in foot-kips required to force the sampling tube through one foot of soil at the depth at which the sample is obtained. Shear Tests The shear tests are run using a direct shear machine of the strain control type in which the rate of deformation is approximately 0.05 inch per minute. The machine is so designed that the tests are made’without removing the samples from the brass liner rings in which they are se- cured. Each sample is sheared under a normal load equivalent to the weight of the soil above the point of sampling. In some instances, samples are sheared under various normal loads in order to obtain the internal angle of friction and cohesion. Where considered necessary, samples are saturated and drained before shearing in order to simulate extreme field moisture conditions. Consolidation Tests The apparatus used for the consolidation tests is designed to receive one of the one inch high rings of soil as it comes from the field. Loads are applied in several increments to the upper surface of the test specimen and the resulting deformations are recorded at selected time intervals for each increment. Generally, each increment of load is maintained on the sample until the rate of deformation is equal to or less than l/10000 inch per hour. Porous stones are placed in contact with the top and bottom of each specimen to permit the ready addition or release of water. Expansion Tests One inch high samples confined in the brass rings are permitted to air dry at 105°F for at least 48 hours prior to placing into the expansion apparatus. A unit load of 500 pounds per square foot is then applied to the upper porous stone in contact with the top of each sample. Water is permitted to contact both the top and bottom of each sample through porous stones. Continuous observations are made until downward movement s,tops. The dial reading is recorded and expansion is recorded until the rate of upward movement is less than l/10000 inch per hour.