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HomeMy WebLinkAbout; La Costa Valley Unit 5; Soils Report Preliminary; 1970-01-16PHl‘IP HENKING eENTON PRISIDEHT ClVlL ENGIHEF” BENTON ENGINEERING; INC. APPLIED 501L MECHANICS ~~- FOIJNDATIONS 6741 EL CAJON BOULEVARD 8AN DIEGO. CALIFORNIA 92115 January 16, 1970 SAN DIEGO: 5ss-565* LA MESA: 469.5654 La Costa Land Company Rwte I, Box 2550 Encinitas, Colifornia Subject: Project No. 69-l I-l4BC Preliminary Soils Investigation La Costa Valley Unit No. 5 Northeast of Alicante Road South of Alga Road San Diego County, California Gentlemen: CONCLUSIONS It is concluded from the field investigation and laboratory test resulk that: 1. The firm to very firm natural soils ore suitable for support of the proposed fills and residential structures. However, expansive cloy soils may occur near the proposed finished gmde in some of the areas and specially designed footirgs and slabs are reccmmended where these expansive soils are allowed to remain in place at depths of less than 3 feet below the final grade. 2. It is recommended that the deposits of soft cloy soils near the surface be removed by excavating horizontol benches in on the firm underlyirrg notural grwrd and placed in layers and compacted during gradirrg . It is concluded from the results of the laboratory tesk that the natural soils such OS those found below 2 .O feet in Boring 2 have a safe beariw capacity of 2300 pounds per square foot for one foot wide continuous footigs placed at a depth of 10 inches below the adjacent mtural grode on firm undisturbed natural soil. The settlement of a one foot wide continuous footi- loaded to 2308 pounds per lineal foot and founded on suitable undisturbed natural soils as described above is estimated to be on the order of l/8 inch. 3. The results of the laboratory expansion tests indicate that the silty cloy and sandy clay soils encountered on this unit would be considered OS “expansive” type soils. Mere these “expansive” soils ore allowed to remain within the upper 3 feet below finished grade, then it is recommended that footings and slabs be specially designed. The required special design will be dependent upon the degree of expansion potential of the soil, the thickness of the layer, and the location of the expansive layer with respect to the footings or slabs. The iok requiring specially designed footiws and slabs will be listed upon the completion of gradiw . Project No. 69-11-l4BC La Cost0 Volley Unit No. 5 -2- January 16, 1970 4. All of the soils may be satisfactorily compacted in the fill areas and, when com- pacted to at least 90 percent of maximum dry derulty, hove a safe beoritg capacity of 2500 povnds per square foot for one foot wide footitqs placed at a depth of IO inches below the compacted ground surface. The settlement of a one foot wide continuws footirg placed on fill soils uniformly compacted to 90 percent of maximum dry density is estimoted to be less than I /8 inch. Recommendations for the placement of filled ground ore presented in the attached Appendix AA, entitled “Standard Specifications for Placement of Compacted Filled Ground .‘I 5. It is concluded from the test data that the proposed cuts may be safely excavated on o slope rotio of 1 l/2 horizontol to 1 vertical too maximum height of 55 feet with a 6 feet wide bench ot 27 feet vertically from the top of slope. The fill soils, when uniformly ccmpacted toot least 90 percent of maximum dry denity in accordance with the approved specification, will be stable for heighk up to 55 feet when constructed on o 1 l/2 horizontal to 1 vertical or flatter slope with a 6 feet wide bench at 27 feet vertically from the top of slope. The slope stability analysis for the cut and fill slopes is presented on Drawing No. Il. The above conclusions include a seismic factor of 0.1 g ond o factor of safety of at lecst 1 .5 and assume that suitable erosional control and proper drainage will be provided to prevent surfclce water from runnig over the top of exposed slopes. These conclusions also apply to the proposed cut bank along Aliconh Road between La Cc&a Volley Unit No. 5 and ik inter- section with Algo Road. 6. It is recommended that the old existirg fills and soft alluvium formig the old reservoir at the easterly end of the project be removed and reccmpacted in accordonce with Appendix AA attached hereto prior to placing additional filled grcund over them. If any soil types ore encountered durirq the groditq operation that were not tested in this invest- igation, odditioml laboratory tesk will be conducted in order to determine their physical chomct- eristics, and supplemental repork and recommerdatiora will outomaticolly become a part of the specifications. The doto presented on the attached pages ore o part of this report. Respectful I y submitted, BENTON ENGINEERING, INC. . B$- - William G. Catlin, Civil Erqineer Reviewed by Philip H. Bent&, Civil Engineer Distr: (4) 81 Addressee Ranch0 La Cata, Inc. Attention: Mr. Burton L. Kramer Rick Ergineerirg Company Attention: Mr. Bob Lodwig 2-27-70 SENTON Mr. John Durham 7-15-71 Project No. 69- 1 l- l4BC Lo Costa Volley Unit No. 5 -3- kmuory 16, 1970 DISCUSSION A preliminary soils investigation has been completed on the proposed Lo Costa Volley Unit No. 5 located northeast of Alicante Rood and south of Alga Road in Section 25 and 36 T12S R4W SBB 8 M in Son Diego County, Colifornia. The obiectives of the investigation were to determine the existirg soil conditiora and to provide information for design of safe and econ- omical slopes and foundations and to comply with the requiremenk of the loan guarantee agencies and the governmental agencies having jurisdiction. In order to accomplish these objectives, four borings were drilled, undisturbed ond lo-e bag samples were obtained, and labomtory task were performed on these sunples. The general topography of the area may be described as moderately to steeply slopiw . The notuml drainage is from the higher northcentral portion of the area to the southeast, south, and southwest. Future drainage will be into streek and storm drain. Accordig to the “Soil Map” prepared by the U. S. Deportment of Agriculture, the upper soils in the area ore described as Las Posos loamy fine sand, ond Diablo cloy. Las Posas loamy fine sand is indicated OS 0.5 foot of friable stony fine sandy loom, I .O foot of slightly compact cloddy stony fine sandy loam, I .O to 2.0 feet of moderotely compact stony fine sandy loam with bedrock below. Diablo cloy is indicated as 0.5 to I .O foot of cloddy cloy, I .5 to 3 .O feet of cloddy moderately compact cloy with bedrock below. The soils encountered in the exploration borlgs were primarily silty cloys, sandy cloys, and some clayey sands. Certain layers of these soils were found to be cemented. Field Investigation The four borings were drilled with buckek rorpig in size from 24 inches to 36 inches in diometer by a truck-mounted rotary bucket-type drill rig at the approximate locations shown on the attached Drawiw No. I, entitled “Location of Test Borings.” The boriqs were drilled to depths of 5.0 to 48 .O feet below the existing ground surface. A continuws Is, of the soils encountered In the baigs was recorded at the time of drilling and is shown in detail on Drawirg Nos. 2 to 9, inclusive, each entitled “Summary Sheet,” The soils were visually classified by field identification procedures in accordonce with the Unified Soil Classification Chart. A simplified description of this classification system is pre- sented in the ottoched Appendix A at the end of this report. Undisturbed samples were obtained at frequent intervals ohead of the drilliw . 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 overage drop was I2 inches. The general procedures used in field sampli~ ore described under “Sanpli~” in Appendix B. Loose bclg samples were also obtained of the representative soils which may be used in compacted filled ground areas. Laboratory Tesk Loboratory tests mre performed on all undisturbed wmples of the soils in order to determine the dry density and moisture content. The resul k of these tesk ore presented on Drawiw Nos. 2 to 9, inclusive. Consolidation tesk were performed on representative samples in order to determine the food-settlment characteristics of the soils and the resutk of these tests ore presented graph- ically on Drawirg No. 10, entitled “Coreolidotion Curves.” BENTON ENGINEERING. INC Project No. 69-ll-l4BC Lo Cost0 Volley Unit No. 5 -4- January 16, 1970 In addition to the above labomtory task, expansion tests were performed on some of the clayey soils encountered to determine their volumetric change characteristics with chorrge in moisture content. The recorded expansion of the samples ore presented or follows: Boriq Sample No. No. 4 5 B-3* B-1’ 2 Depth of Sample, in Feet 20.0 25.0 7.0-8.0 6.0-7.0 8.0 B-l* 6.0-7.0 Percent Expansion Percent Exporrion Under Unit Load of Under Unit Load of 150 Pwnds per Square 500 Pounds per Square Soi I Foot from Field Foot from Air Dry Description Moisture to Soturotion to Saturation Light olive 3.94 silty clay Light olive 5.63 silty cloy Light 01 ive 7.80 silty cloy Light olive 10.87 silty cloy Light olive- 3.57 gray very fine sandy cloy Light olive- 6.02 gray very fins sondy cloy ’ lndlcates sample WQ remolded to 90 percent of maximum dry density. The general procedures used for the laboratory tesk ore described briefly in Appendix B. Compaction tesk were performed on representative samples of the soils to be excavated to establish compaction criteria. The soils wre tested occordirg to the A.S.T.M. D 1557667 method of compaction which uses 25 blows of a 10 pcund hammer droppiw 18 inches on each of 5 layers in o 4 inch diameter l/30 cubic foot mold. The resufk of the tesk ore presented OS follows: Maximum Optimum Mois- Borig b Depth Soi I Dry Density ture Content No. Sample in Feet Description Ib/cu ft % dry wt 1 1 .O- I .O Dark gray cloy (topsoil) 114.0 16.1 1 2 2 .O- 3.0 Light olive, silty very 118.3 12.2 fine sond 1 3 7.0- 8 .O Light olive, silty cloy 122.1 II.2 2 1 6.0- 7.0 Light olive, silty cloy 117.0 13.7 with silktone 2 2 18.0-19.0 Light olive-grey silty 121.8 11.6 fine to medium sand 4 1 6 .O- 7 .O Light olive-grey, very 122.3 10.2 fine sandy cloy mENTON ENOINEERING. INC. Project No. 69-ll-14BC La Costa Valley Unit No. 5 -5- January 16, 1970 Atterberg limit tesk were performed on selected samples of the soil and the resufk ore presented below: Liquid Plastic Plasticity Group Limit Limit Index Symbol Borilrg l,Sample 1 47.6 14.6 33.0 CL Depth 5.0 feet 8orig 1, Sample 4 37.5 15.8 21.7 CL Depth 20.0 feet Borirg I, Sanple 5 40.0 14.9 25.5 CL Depth 25 .O feet Bori rg 2, Sample 1 54.8 14.5 40.3 CH Deprh 5.0 feet Direct shear tesk were performed on saturated and drained samples in order to determine the minimum orgle of internal friction and apparent cohesion of the voriws soils the tests were as follows: Borlrg 1, Sample 3 Depth: 15.0 feet Boring 1, Sample 5 Depth: 25.0 feet Boring 2, Sample 1 Depth: 5.0 feet Boriw 2, Beg l* Depth: 6.0-7.0 feet Bait-g 2, Bag 2’ Depth: 11 .O feet Normal Sheariw Load In Resistonce kips/sq ft kip/sq ft 0.5 1.66 1.0 5. I3 2.0 4.23 0.5 2.35 1.0 5.74 2.0 6.74 0.5 1.0 2.0 0.5 1 .o 2.0 0.5 1.0 2.0 I.10 1.49 1.72 1.73 1.95 2.25 0.76 1 .15 1.95 Argle of Internal Friction Degrees 45** Apparent Cohesion lb/sq ft 800 45** 800 14 17 38.5’ 975 1550 375 The resuf k of l Indicates tesk were performed on samples melded to 90 percent of maxlmum dry det&ty . l * Arbitrarily reduced to allow for local cementation. BENTQN ENGINEERING. INC. Proiect No. 69- I I- 14BC Lo Costa Valley Unit No. 5 -6- January 16, 1970 Normal Sheoritg Load in Resistonce kips/sq ft kips/sq ft Bcrig 4, Bag I’ 0.5 Depth: 6.0-7.0 feet 1.0 2.0 Borig 4, Sample 3 1.0 Depth: 13 .O feet 2.0 Borig 4, Sample 5 0.5 Depth: 23 .O feet 2.0 1.05 1.22 1.84 3.34 5.51 I. 10 3.64 Argle of I nhrnal Friction Degrees 28 Apparent Cohesion lb/sq ft 725 45** 1000 45” 275 * Indicates lurk ware performed on samples melded ta 90 percent of maximum dry density ** Arbitrarily reduced to allow for local cement&ion Usirg the lower values of the argle of internal friction ond apparent cohesion, and the Terzoghi Formula for local shear failure, the safe ollowoble bearirrg pressures fcr the soils ore determined as follows: Local Shear Formulo: Q’d = 28 (2/3 c N’, + Y Df Nlq + Y BN’y) Assumptiofl: (I) Continuous footig 1 foot wide = 28 (2) Depth of footiw = 0.83 = Df Undisturbed natural soils Firm soils as Boriw 2, Sample I @ = 140 c = 975 I b/sq ft Y = 120 Ib/cu ft N’c = 10.0 Nlq = 4.0 N’y=2.0 QId = (2/3 x 975 x 10 + 120 x .83 x 4.0 + 120 x 0.5 x 2 .O) = 7020 lb/sq ft Q’d f Factor of Safety2 3 Use maximum of 2300 Ib/sq ft Fill soils canpacted to 90 percent of maximum dry demity @=2E” c = 725 lb/sq ft Y = 120 Ib/cu ft N’, = 17.0 Nlq = 8.0 Nly =4.8 Q’d =(2/3x725x l7.0+ 120x .83x 8.0+120x 0.5x4.8)=9310lb/sq ft Q’d + Factor of Safety, 3.0 Use maximum of 2500 Ib/sq ft BENTON ENaINEERING. INC. SUMMARY SHEET Sllahtlv Moist. SILTY VERY FINE SAND SILTY CLAY rg No. 3 G&rued on D&vi ~a - ‘IndIce& U*t+&ed Drive Sample ’ ” 0 -, lndlcahr Loaw W’Saple II.: 18.2 12.8 06 22 18 l -, The elwqtlofir ahown on these Sumnary Sheets were obtoincd by interpolation of th&.contoun on a Tentotive Map of La Costa Valley .:,: Unit No. 5 prepared by Rick E~ineerig Compony ,, ,, ~;” \ si,,: :L ?-JI$~&~:- ~.’ BENTW ” E+INE$W, wyCs, DRAWING NO. ,: ~.,. I ;>,;i ,:, ,” ~,,~ ;, e; ;: ,.,,, ._ ::;.-,:, : *, m.mj--iii!; ~,. I .: ,;::q ‘Y./. b,;$i:‘“: ,.,,! ,,‘., t, ~;;,. ,< ^;: :,:: $,.; ,, ,_ ,. * i:.; * :~;, S,,~~. ,g j g; (2,: - :1.: 13. - 3.i - ~* .: :, :1 ,’ ~. ,,, :, ,:. :,;’ i ,~ ;‘h ;:g -k z IL tit : -O- l- 2- 3- 4- 5- 6- 7- 8- 9- 10 11: 12- 13- 14- 15- 16 ,‘E SUMMARY SHEET OP 5: BORING NO.Lv. “2 ELEVATION 1u Contlnud on C ;RAVELLY CLAY CLAY SILTY CLAY - 8.1 t . p j: ‘> ;z > A - CH PROJECT NO. 69-l 1-14BC I BENTON ENGINEERING, INC. DRAWING NO. 4 SUMMARY SHEET BORING NO.-11S;Pnt.) 18 Light Olive-gmy, Molrt, Very Firm, Lightly Cemented waGnted Sandstone SILTY CLAY l!!!mid- SlLTY FlNE TO MEDIUM SAND 59.0 i0.8 - z; i& :EC =,! - 10.2 10.3 : ; ; a ; : ’ > ! a c 1 1 ! 11 17, 09. - PROJECT NO. DRAWING NON 69-1 l-14BC BENTON ENGINEERING, INC. 5 = - c FE z !!is SUMMARY SHEET 5i ,<tti Eti Pm. Et ng; wz ;;- 2: BORING NO. 3 E g 222 g 2 $33 Y Y -- 0 “Z ELEVATION 45.0’ $k LOO > ~ i j;$? 0 L$ n 4 zg - CLAYEY FINE Medium Firm, Scattered Grovel iEi 2 .‘. . . g&4 . . G( A, i Gray, Molat, Very Firm, GRAVELLY FINE 20 Percent Gmvel to 2 Inches TO MEDIUM r16.hl5.5tll4.6i 5 warown, Moist, Veii Firm 1 SANDY CLAY / --.-I ---I ~--I NE TO \. 1 MEDIUM SAND ’ Brown, Moist, Very Firm, 1 CLAYEY FINE TO lCLAYEY FII to b0 Per&t Gkvel & MEDIUM SANDY 3 Inches, Cobbles to 8 Inches PROJECT NO. 69-11-14BC BENTON ENGINEERING, DRAWING NO. INC. 6 SUMMARY SHEET BORlNG NO.4 ELEVATION 9 1.0’ -0 1 2 3 Light Gmy-brown, Molst, Very Firm 4 I;;;; E J if---- “’ “” ‘. Light Olive-gmy, Moist, ..,. F ..’ (. :::I Very Firm, With Some c-~ :.: , ,,,,.: ‘/‘$‘:‘/ Alternating Layrrs of Silty Clay to 10 Feet 1 1 1 1 Continued OtlC FINE SANDY CLAY tLAYEY FINE TO MEDIUM SAND VERY FINE SANDY CLAY (M-a4 VERY FI NE SANDY SILT wig No. 8 14.6 15.7 19.0 !9.2 12. 12. Il. i 3; CI 0. s ( i a 1 1: 1 11 i 61 08.: 20.4 19.t 19.: - - - - PROJECT NO. 69- 1 l- 14BC BENTON DRAWING NO. ENGINEERING,. INC. 7 I I I I I 1 SUMMARY SHEET BORING NO.-t!.&ont .) Ii ! ; Ls I- 5: El: “i; it: 3 - - 9.5 : / 2 : ! _ ; ! - 13 :: I;.: 22 :i+::: PA 23 24 v, 25 26 Thin Soft Plastic Clay Seam, Dlpr Down 28’ at Bearlw Red-brown, Brown and Gray Moist, Very Firm Continued on Dmwirg No. 9 VERY FINE SANDY SILT (Memos) SLIGHTLY XAYEY FINE TO MEDIUM SAND SILTY CLAYSTONE C :LAYEY FINE SAND 5.0 0.0 5.0 0.4 9.4 8.5 7.1 t m 10 - 17, - - - - PROJECT NO. 69-11-14BC BENTON DRAWING NO. ENGINEERING, INC. 8 UJ 0 .t 3 > 0 = 3 j 3 I j 3 2 2 ! z SUMMARY SHEET c EE !!f; k’ P 3 z -1 BORING NO..rl.lCont.) a*. I I “” . . . . . M Red-brown, Brow and Gray, 41 . . . . . 42 ft;;f El .+. 43 I..:: CLAYEY FINE SAND PROJECT NO. 69- 1 l- 14BC BENTON DRAWING NO. ENGINEERING, INC. 9 I - 6.6 I 1 6.0 6.2 17.7 17.7 I.- + ._ s 1 E c. c -g : CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT I ! + t 1 t t + T 1 t -1 i .A o Indicates percent consolidation at field moisture l Indicates percent consolidation after saturation t PROJECT NO. DRAWING NO. rn 1, ,.OP BENTON ENGINEERING, INC. 10 i ~ ---- ~ 1 fq 11 -A-.- ~ +, -y-~~~ i / j I li~i/ j ei i t-i ! 1 t --J -... ++.. /_- / j I iI / \. /\ i / .?w ST 4 d/.g&=” * t3 T. r-Lo . “t . w, - ers: rz.z & yzo _ ::,;\F 90 % ZAO x,?JJ e 50. SL- +9 ad. r*r- 6 = /I)5 I,?.0 - /A0 /so ~6.2 Ur’ =p k b.6 . I ‘L-0 4O.G 36.6 /Z.‘? We ./‘ s&i I ,*.o ,‘ZO ‘, /SC+ ,6.4 s /72.4 /c7,7,7 F;r. G;&J _ v- 2.53’ /7&P 7-q .za o -~2~7Z~;I. 9/c99/3 .&pox. /-=v 7 x%7 L - 725 %w- p-/c* L BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS - FO”NDATIONS 6717 CONVOY COURT SAN DIEGO. CALIFORNI* 92111 PHlLlP “ENKlNO BENTON ,“LS,DLHI ClYlL ENe3lNlLI APPENDIX AA TLLEPHDHF (71.3, Li6S.IBSB 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 tests 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 ond 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 responsibility 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”), 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 provide 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 eleva- tion 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 -2- (d) 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 meld of a 1/30th cubic foot volume. 3. Materials and Special Requirements. The fill soils shall consist of select materials so graded that at least 40 percent of the material passes a No. 4 sieve. This may 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 streqth 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 ihe 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 rights-of-way shall be in accordance with those of the governmental agency havirg jurisdiction. 4. Placing, Spreading, and Compactiw Fill Materials. (a) 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. (b) When the moisture content of the fill material is bellow that specified by the soils ewineer, 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. (c) 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 scarifyirg or other satis- factory methods until the moisture content is near optimum as specified by the soils engineer. (d) 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 fill material to the speclfled density. Rolling shall be accomplIshed while the fill materlal is it the speclfled moisture content. Rollirg of each layer shall be continuous over lk entire area ond the roller shall make sufficfent trips to insure that the desired density has been obtained. The entire areas to be ff lled 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 omount of loose soil on the slopes. Compacting of ihe slopes shall be accompllshed by backrolliq the slopes in Increments of 3 to 5 feet in elevation gain or by other methods producing satisfactory results, (fJ Field density tests shall betaken by ihe soils ergineer 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 ergineer. The location of the tesk In plan shall be so spaced to give the best pastble coverage and shall be token no farther apart than 100 feet. Tests shall be taken on corner and terrace lok for each two feet in elevation gain. The solls ewgtneer may take additional tests as considered necessary ta check on the uniformity of compactlon. Where sheepsfoot rollers ore used, the tests shall be taken in the com- pacted materlal below the dIsturbed surface. No additional layers of fill shall be spread until the field density tests indicate that the specified density has been obtolned. (9) The fill operation shall be continued in six inch (6”) compacted layers, as specified above, until the fill has been brought to the flnlshed slopes and grades as shown on the accepted plans. 5. Inspection. Sufffctent Inspection by the soils engineer~shall be maintained durfllg ihe fillip and compacti- operations so that he con certify that the fill was constructed in accordance with the accepted specificotlons. 6. Semoncd Limits. No fill materiol sholl be placed, spread, or rolled if weather condltlons increase the moisture content above permissible llmik. When the work is interrupted by rain, fill operations shall not be resumed until field tests by the soils ellglneer indicate that the moisture content and density of the fill ore as previously specified. 7. Limitlw Values of Nonexpansive Soils. Those soils that expand 2.5 percent or less from air dry to saturation under a unit load of 500 pounds per square foot are considered to be nonexpcmslve . 8. All recommendations presented in he “Conclusions” secHon of the attached report ore a part of ihere speclflcatlons. BEFiTON ENGINEERING, INC. APPLIED SOIL MEC”ANICS - FO”NDAT,ONB 8717 CONVOY EOVRT BAN DIEGO. CALIFORNIA 92111 PHlLlP HLNKINO BENTON C”I.IDIHI CIVIL LNGlNLLl APPENDIX A Unified Soil Classification Chart* SOIL DESCRIPTION GROUP SYMBOL I. COARSE GRAINED, More than half of material is b than No. 200 sieve size.** GRAVELS CLEAN GRAVE LS s half of coarse fraction is larger than No. 4 sieve size but SmallerGRAVELS WITH FINES than 3 inches (Appreciable amount of fines) SANDS CLEAN SANDS More than half of coarse fraction is smaller than No. 4 sieve size SANDS WITH FINES (APP reciable amount of fines) II. FINE GRAINED, More than half of material is smaller than No. 200 sieve size.** 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 or 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 graded 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. Inorganic clays of low to medium plas- ticity, gravelly clays, sandy clays, silty clays, lean clays. Organic silts and organic silty-clays of low plasticity. Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorganic clays of high plasticity, fat clays. Organic clays of medium to high plasticity PT Peat and other highly organic soils. TYPICAL NAMES TFLEPI”ONE ,714, ,115-,8SS * Adopted by the Corps of Engineers and Bureau of Reclamation in January, 1952. ** All C~PVP ci~m nn this rhnrt ore LJ. 5. Standard. BENTON ENGINEERING, INC. *PPLIED BOIL MECHANICS - FOUND*T,ONS 6717 CONVOY COURT SAN DIEGO. C*LIFORN,* BZ,,, PHlLlP “ENWNG BENTON CIISID~N, CIYIL LNDlNIL” TELLS-HONE (714, 58s-18es 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 cutting 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 moisture 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 secured. 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 rote 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 mode until downward movement stops. The dial reading is recorded and expansion is recorded until the rate of upward movement is less than l/10000 inch per hour.