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HomeMy WebLinkAbout; La Costa Valley Unit 5 Arroyo Villas; Soils Report; 1973-04-12I’--” e *I’ ‘-7~ PHlLlP HENKING BENTON PRESI”eNT. CSVIL EHTI(ICER BENTON ENGINEERING, INC. APPLIE” SOIL MECHANICS ~~~ FO”NDA1IONS 6717 CONVOI COURT SAN “IEGO. CALIFORNIA 82111 April 12, 1973 American General Finance Corporation Suite 205 111 Elm Street San Diego, California 92101 Attention: Mr. Peter Baborovich Vice President Gentlemen: - This is to transmit to you five copies of our report of Project No. 73-3-26A entitled, ‘up,,- osed Arroyo Villas Condominium, Lot 245 of La Costa Valley Unit No. 5, Ranch0 La Costa, - Co&bad, California,” dated April 12, 1973. -~ - We ore transmitting under separate cover one copy to G.F.D.S. Engineers, 1620 Montgomery Street, San Francisco, Califomio 94111, to the Attention: Mr. Ed Dickmann, per your request. If you should have any questions concerning any of the data presented in this report, please contact us. Very truly yours, - BENTON ENGINEERING, INC. - - - - - SlOlO .17.93 SOILS INVESTIGATION - - - - - - - - - Proposed Arroyo Villas Condominium Lot 245 of La Costa Volley Unit No. 5 Roncho La Costa Carlsbad, California American General Finance Corporation Project No. 7%3-26A April 12, 1973 BENTON ENGINEERING. INC, BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS -~~- FOUNO*TIcJN* 6717 CO~“OY COURt SAN DIEGO. CALIFORNIA 82111 PHILIP HENKING BENTON PIILBILXNT ClYlL ENGINLER SOILS INVESTIGATION TELEPHONE (714) 5654955 - - -~ - -. - - - - Introduction This is to present the results of o soils investigation conducted at the proposed Anoyo Villa Condominium site located easterly of the intersection of Altisma Way and Coringa Way on Lot 245 of Lo Costa Volley Unit No. 5, Ranch0 La Costa, Carlsbod, Cnlifomio. The propcxed construction includes three building units at different pad elevations. The proposed finished grades of the northernmost units will be at Elevations 78.5 to 80.7 feet with subterranean garage floors at Elevations 69.5 to 71.7 feet. A retaining wall up to approximately 5.6 feet in height will be constructed along the north property line. Also, o swlmming pool is being planned in the northernmost unit of structure. In the middle portion of the site, the build- ing will have finished floor elevations varying from 73.4 to 79.0 feet and subterranean garage floors at Elevations 64.4 to 70.0 feet. In the southernmost of the site, the proposed garage floor elevations will be ot Elevotionr 65.0 to 74.0 feet with subterranean building floors al Elevations 47.0 to 56.0 feet. In order to bring the site to the proposed finished grades, excavations up to approximately 10 feet will be required in the northern portion of the site and excavation up to approximately 14 feet of compacted filled ground will be required in the southern portion of the site. Also, o new fill up to 14 feet in thickness will be required between the central building and the south building. The objectives of this investigation were to determine the existing subrurfoce conditions of the site and to determine the major physical properties of the soils, SO that representative soi1 -2- design parameters could be presented for on economical and safe design ond constructlon of the bullding foundations and retaining walls. -, In order to accomplish these objectives, three borings were drllled at selected locatiom, and undisturbed and loose soil sanples were obtalned far laboratory testlng. This study was based on the groding plan prepared by Tri State Engineering Canpony, of Fullerton, Califomio and doted January 29, 1973. The plan also contalned working drawings made by Aesthetfka, the project Architectural ond Planning Consultants and dated ‘January 2, 1973. The plan was provided to us by the American General Finance Corporation of Son Diego, California. - Field Investigation The three borings were drilled with o truck-mounted rotary bucket-type drill rlg at the approximate locations shown on the attached Drawfng No. 1, entitled “Location of Test Borings.” - The borings were drllled to depths of 23.0 to 47.0 feet below the existing ground surface. A continuous log of the soils encountered in the borings was recorded at the time of drilling ond is - shown in detail on Drawing Nos. 2 to 8, inclusive, each entitled “Summary Sheet.” - The soils were visually classified by field identification procedures in accordance with the - Unified Soil Classiflcotion Chart. A simplified description of this classification system is presented In the ottoched Appendix A at the end of this report. Undisturbed samples were obtained ot frquent intervals, where possible, in the gravel free soils aheod 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 overage drop was 12 inches. - The general procedures used in field sampling ore described under “Sampling” In Appendix B. Laboratory Tests Laboratory tests were performed on all undisturbed samples of the soils in order to determine the dry density and moisture content. The results of these tests ore presented on Drawing Nos. 2 to - BENTON ENGINEERING. INC, -3- 8, inclusive. Consolidotlon tests were performed on representotive sanples in order to determine the load-settlement characteristics of the soils and the results of these tests are pmsented graphically on Drawing No. 9, entitled “Consolidattan Curves.” The general procedures used for the laboratory tests are described brfefly In Appendix B. In addition to the above labomtory tests, expansion tests were performed on representa- tive clayey fine sand and clayey silt soils encountered to determine their volumetric change characteristics with change in moisture content. The recorded expansions of the samples are presented 01 follows: Depth of Boring Sample Sample, No. No. in Feet 1 5 13.0 2 2 3.0 2 4 12.0 2 5 17.0 Soil Description Silty clay Mixed clayey fine sand and sandy clay Clayey silt Clayey silt Percent Exponslon Under Percent Expansion Unft Loads of 150 And Under Unit Lood of 2ooO Pounds per Square 150 Pounds per Square Foot from Field Foot from 2 Days Dry Moisture to Saturation to Saturation 0.15% At 2000 p.s.f. 4.50% At 150 p.s.f. 1.004h At 150 p.s.f. 0.46% At 2000 p.s.f. 8.68 9.80 Direct sheor tests were performed on selected undisturbed samples that were all sotumted ond drained prior to testing. The results of these tests are presented below: - Boring 1, Sample 1 Depth: 1.5 feet Normal Load in kips/sq ft 0.5 1.0 2.0 Moxlmum Shear Load kips/sq ft 0.87 0.73 1.14 Angle of lntemol Friction Degrees 21.5 Apparent Cohesion Ib/sq ft 330 Boring 1, Somple 4 Depth: 10.0 Feet 0.5 0.73 31.5 420 1.0 1.04 2.0 1.84 BENTON ENGINEERING. INC. -4- - - - - - - - .- - - - Normal Lood in kips/sq ft Boring 2, Sample 4 0.5 Depth: 12.0 Feet 1.0 2.0 Boring 3, Sample 4 6.5 Depth: 16 .O Feet 1.0 2.0 Maximum Shear Load kips/sq ft 2.13 2.33 2.63 Angle of Internal Friction Degrees 18.0 Apparent Cohesion Ib/sq ft 1970 1.40 t 1.81 14.5 * Not enough undisturbed sample to test at this normal lood. A compaction test was perfcrmed on a representotlve sample of the existing fill soils in order to estobllh the maximum density at optimum moisture content. The soils were tested occord- ing to the A.S.T.M. D 1557-70 method of compaction which uses 25 blows of a 10 pound rammer dropping 18 inches on each of 5 loyers in a 4 inch diameter l/30 cubic foot meld. The results of the tests are presented as fol lam: Maximum Boring Bag Depth SolI Dry Density No. Sample In Feet Description I b/cu ft 1 2 9.0-10.0 Silty very fine to 124.4 fine sand Optlmum Mofs- turn Content % dry wt 9.7 DISCUSSIONS, CONCLUSIONS AND RECOMMENDATIONS Soil Strata At Boring 1, an existing fill was found throughout the depth of the boring. The fill soils consisted of a soft clayey fine sand to a depth of 0.5 foot, that merged to fhm between 0.5 foot and 8.0 feet of depth. Below 8.0 feet, the fill solls consisted of firm silty very fine to fine snarl to_l,!,,t5V2&o firm silty clay to 18.5 feet, a gravelly clay and clayey fine to medium sand to 21 .O feet and o firm clayey fine to medium sand with mottled loyen of fine to medium sandy clay~t6 32.0 feet, a firm and gravelly clayey fine to medium sand to 35.0 feet and a firm clayey fine,to medium sand with mottled layers of fine to medium sandy cloy to theend of boring at 47.0 feet. BENTON ENGlNEERING. INC. - - - - - - - - -5- At Boring 2, an existing clayey fine sand fill with fine sandy cloy was encountered to a depth of 7.0 feet. The upper 1 .O foot of fill soils worn soft that.meged to firm between 1 .O foot and 7.8 feet. Below 7.0 feet, a firm and groveily clayey fine to,medium sand with approximately 30 percent of grovel and cobbles to 6 inches in diameter was found to a depth of 10.0 feet and then merged to firm clayey silt to the end of boring at 23.0 feet. At Boring 3, a clayey flne to medium sand fill mixed with sandy clay was found to a depth of 3.5 feet that wos soft to one foot and then very firm. A very firm clayey fine to coarse sand was found to a depth of 9.5 feet. Below 9.5 feet, o 1.5 foot thickness of gravelly clayey fine to medium sand was underlain by a very compact slightly clayey fine to medium sond to a depth of 15.0 feet and by a very compact alternating layers of silty fine sand, slightly clayey fine to medium sand and slightly silty fine to medium sand to o depth of 20.0 feet. A very compact slightly silty fine to medium sand was then found to the end of boring at 31 .O feet. No gmund water was encountered in any of the three borings. conclusloN It is concluded from the results of laboratory tests and field explorations that the existlng fills found between the depths of proposed finished grades in Boring 1 area hove fovorable densities shearing strengths ond lood-settlement chomcteristics. However, the mixed clayey sand,ond sandy cloy, silty clay and gravelly clay fills between 0 and 8.0 feet ond between 11.5 ond 21 .O feet are highly expansive. Also, the upper 7.0 feet of mixed clayey sond and sandy clay soils and the in-place clayey silt found 10 feet below existing ground surface within the proposed garage floor elevations In-20 is moderately . Therefore, the footings and concrete slab-at-grade for the north unit building and control unit building should be specially desIgned for expansive soil conditions with exception thot when footings are to be placed ot Elevations 68 or 69 feet in Boring 1 area, then no special design is required provided 2.5 feet or greater thickness of non-expansive silty sand soil is found to unifcrmly exist beneath these footings. - REN70N ENGINEERIN(i. tNC, -6- - - - - - - The horizontal limits of this layer are unknown, therefore, to be on the safe side oil foundations should be designed for expansive conditions. For south unit building, the in-place slightly clayey fine to medium sand found below the depth of 11 .O feet and the cltemoting layers of slightly clayey sand and silty and slightlysilty sond found below thee depth of 15 feet in Boring 3 oreo hove fovoroble physical charoctertstic% These soils may be used to support the building foundations and concrete slabs-at-grade without special design where the foundations ond slobs are to be placed below Elevation 54.5 feet on the gravelly clayey fine to medium sand or slightly clayey sand soils. For those wlth proposed finished grodes at Elevation 54.5 feet or higher in Boring 3 area, special design of footings and concrete slobs-at-grade will be required for expansive soil conditions because of the potentially expansive clayey ftne to medium sand found in the upper 9.5 feet of Boring 3. Recommendations 1. Allowable Bearing Values The allowable bearing volues that may be used in foundation designs for the propased three units of building are presented below: North and Central Buildings South Building 2-Foot Wide I-Foot Wide 2-Foot Wide l-Foot Wide Square Footing Continuous Footing 5quare Footing Continuous Foottng ** * ** l l * l ** ca Case (B) Case (A) Case (B) Core (A) Core (B) Case (A) Case (B) Recommended 2 1 2 1 2 1 2 1 Minimum Depth Below Lowest Adjacent Undisturbed Grodes (Feet) Allowable 3700 4ooo 3008 4ooo 3700 3808 3000 3000 Beoring Values At Minimum Depths (Ib/sq ft) Note: * Case (A) for footings in expansive soils ** Case (B) for footings in non-expansive soils - - BENTON ENGINEERING. INC. -7- North and Centml Buildings South Building 2-Foot Wide Square Footing Gas: (A) k: (B) Allowable 370 1000 Increase For Each Additional Foot of Depth Below Minimum - Depth (lb/sq ft) Allowable 130 400 lncreose For Each Additional Foot Of Width At - Some Elevoticn W&q ft) Reccmmended 5OOU 6000 - Maximum Value Wxl ft) 1 -Foot Wide 2-Foot Wide l-Foot Wide Continuous Footing l l * ?uare Fyiing Continuous !Fting Case (A) Case (B) Case (A) Case (B) Case (A) Case (B) 370 1000 370 180 370 180 160 500 130 40 160 50 4500 6000 5000 8000 4500 6000 Note: l Case (A) for footings in expansive soils ** Case (B) for footings in non-exponsive sofls The values presented for continuous footings may also be used for retaining wall footings. These values ore for dead plus live loads ond may be increased one third for cambined, dead, live, wind and seismic loadlngs. The one-third increase may also be allowed for edge pressures of a retaining wall footings. It is assumed that all footings will be placed at least 5 feet inside of ony final expcsed sloping ground surface. 2. Settlements - - - - - The estimated maximum total settlements of footings of vorious widths and loaded to 5000 and 4000 pounds per square foot for square footings and continuous footings, respectively, were estimated ta be as follows: ESENTON ENGINEERING. INC. -8- - - - - - - - - - - - - - Estimated Settlements (Inches) North and Central Buildings South Building Footing Widths (Ft) Square Footing (5000 Ib/sq ft) Continuous Footing Square Footing Continuous Footing WJO It&q ft) (5000 ib/sq ft) (4000 Ib/sq ft) 1 0.08” - 0.09” 2 0.14” 0.16” 0.14” 0.17” 3 0.18” 0.20” 0.19” 0.21” 4 0.22” 0.25” 0.23” 0.26” 5 0.26” 0.29” 0.27” 0.30” 6 0.28” 0.32” 0.30” 0.33” if concrete slobs, loaded to 150 pounds per square foot, and footings loaded to 2000 pounds per square foot are placed in the exponslve soils the following upword movements could result if the foundation bearing soils am saturated. From Field Moisture Condition From Air Dried Conditions ‘All Buildings All Buildings Square Footing Concrete Slob Square And Concrete And Continuous Footings on Grode Continuous Footing Slob (2000 Ib/sq ft) (150 Ib/sq ft) (2000 Ib/sq ft) (150 lb/sq ft) 0.16” 0.36” 0.75” 2.5” to 3.5” 3. Earth Pressures For Retaining Wall Design The active earth pressures that may be used for designing both restrained type of bosement walls and cantilever type retaining walls ore presented OS follows: All Buildings (A) No Pervious Backfills Immediately behind The Walls Restrained Wail (Ib/sq ft)” Cantilever Wall (Ib/cu ft equivalent fluid density) 37 H p.s.f. (CJ) Level Backfill 58 (b) 1.5 horizontal: to 1 vertical sloping bockfill p.c.f. 120 p.c.f. * The pressure intensities ore assumed acting uniformly in the middle 60 percent of the height of wall ond diminishing to zero at both restrained points. H is the height of wall in feet. BElrrO;” LNGINL:ERI, “, Ih -9- All Buildings (B) With Pervlaus Backfills At Least 2’ In Thickness Immediately Behind the Walls Restrained Wall (Ib/sq ft) l Cantilever Wall (Ib/cu ft equivalent fluid density) (a) Level Backfil I (b) 1.5 harlzontal to 1 vertical sloping backfill 19 H p.s.f. 30 p.c.f. 57 p.c.f. - * The pressure Intensities are assumed acting uniformly in the middle 60 percent of the height of wall and diminishing to xera at bath restrained points. H Is the helght of wall in feet. It is assumed that proper drainage devices will be installed behind the walls so that no - hydrostatic pressures will be developed In the retained earth behind the walls. If any surcharge loads, such traffic loadings or permanent live loads, are to be placed behlnd the walls, the pressures due ta these surcharge loads should be added to the values shown above. Where pervious backfills at least 2.0 feet in thickness are ta be placed behind the walls, the pervious backfill may consist of clean sand or crushed gravel or rocks. If clean sand is to be used, it should be compacted ta at least 90 percent of the maximum dry density per A. S.T.M. - D 1557-70 method of cunpaction described in Section 9 under “Site Grading.” If crushed gravel or rocks are to be used, these should be compacted to the densest state passible. - 4. Swimming Pool Design In that moderately to highly expansive soils were found below the proposed swimming pool in the north building area, it is recommended that a minimum thickness of 6 inches crushed rock - be placed below the concrete bottom and that provisians for a drainage sump and outlet be pro- - vided beneath the pool. If the walls of the pools are double-formed, a grovel or crushed rock backfill is recommended between the pool walls and the soils. - The pool walls should cast dfrectly against the expansive soils should be designed for an - equivalent fluid pressure of at least 60 pounds per cubic foot. BENTON ENGINEERING. INC, -lO- 5. Lateral Rssistance Design The allowable passive pressures and the friction coefficient that may be used for determin- ing the resistances of foundatlon bearing soils against lateral forces such as wind and sekmic loadings are presented as follm: Case (A) Allowable Passive Pressures At The Depth of 1 .O Foot Below the Lowest Adjacent Undisturbed Grade of Bearing Soils (Ib/sq ft) Allowable Increase of the Above Values For Each Additional Foot of Depth Below 1.0 Foot (lb/sq ft) Frictional Coefficient All Buildings 600 130 0.3 Case (B) Non-expansive Soils North And Central Buildings SC&h Building 900 1100 190 90 0.4 0.4 6. Excavation Slopes And Erosion Control The allowable maximum heights of cut slopes that could stand safely with an adequate factor of safety along the south and the north boundaries of the site is 20 feet, a 1.5 horizontal to 1 vertical slope. If existing conditions differ from those indicated above, the slopes should be changed to a flatter slope. It is recommended that adequate drainage devices and suitable erosion control &vices be provided atop of the cu’t slope and around the whole site in order to prevent surface runoff from sheeting over the cut slopes. In that the subject property is located in the downslope side of an existing canyon, the drainage dev~ices should be large enough to cal-ry the surface runoff from all contributary areas adjacent to the property. excavallons should be made In conformance with the Construction Safety Orders of the Skate of California Department of IndusMal Relatiom and it shall be the sole mspomlblllty of the Contractor to provide adequate safety precautiom. BENTON ENGINEERING. INC - -ll- 7. Mlnimum Recommendation for Expamive Sail Design Wherever potentially expansive sandy clay, silty clay and clay sail mixture exists below finished grade, it is recommended that the foundations and slabs be specially designed in order to minimize the adverse effeck of differential movements of the potentially expansive soils: d. Avold the use of isolated interior footings. Use continuous interconnected reinforced footings throughout, and place these at a minimum depth of two feet below the lowest adjacent un- disturbed exterior final ground surface. b. Reinforce and interconnect continuously with steel bars all interior and exterior footings with at least one #5 bar at 3 inches above the bottom of all footings and at least one #5 bar placed 1 l/2 inches below the top of the sterna of the footings. C. Reinforce all concrete slobs with at least 6 x 6 - lo/10 welded wire fabric. d. Provide a minimum of 4 inches of crushed rock 3/4 inch to 1 inch in size beneath al I concrete slabs. Provide a moisture vapor barrier 2 inches below slobs under living areas and two inches of sand between the vapor barrier and concrete slob to allow for proper curing. 0. Separate garage slobs from perimeter footings by l/2 inch thickness of construction felt or equivalent, to allow independent movement of garage slobs relative ta perimeter footings. Assure complete separation by extending the camtruction felt over the full depth of the front thickened edge of the garage slab. Cut off garage door stops at least l/2 inch above the garage slab. Provide positive drainage away from all perimeter footings tu a horizontal distance of at least 5 feet outside the house walls. - - - BENTON ENGINEERING. INC. -12- 8. Concrete Floor Slabs At Grade One alternative far concrete floor slab design is ta remove the existing soils underlying the proposed slabs-on-grade areas to a depth of 2.0 feet below the subgrade soils. The excavated soils should then be replaced by select nonexpansive import soils properly compacted to the sub- grade elevations by the procedures described in the following section under “Site Grading.” If this olternotive is used, the concrete floor slabs in the north building and central building areas may be placed directly upon the compacted nonexpansive soils. The selected nonexpansive mat- erials should either be silty sand, clayey sand or sandy soil type that cartalns less than 40 percent passing the No. 200 sieve size. Also at least 50 percent of the soils should pass the No. 4 sieve size ond it shall contain no grwel larger than 3 inches in diometer. The expansion of a one inch high sample of the minus No. 10 material remolded to 90 percent of the maximum dry density and then air dried for two days at lOsoF, then loaded to 150 pounds per square foot and saturated, shall not exceed two percent. If concrete floor slabs at grade are to be constructed below Eleva- tion 54.5 Feet in the area of the southernmost unit of building, the concrete floor slobs may be placed directly upon thein-ploce gravelly, clayey fine to medium sand, slightly clayey fine to medium sand or slightly clayey fine to medium sand alternating with layers of silty fine sand and slightly silty fine ta medium sand found below the depth of 9.5 feet in Boring 3 area provided the subgrade soils are not disturbed during gmding . If the concrete floor slab at grade are to be constructed above Elevation 53.0 in the upper 9.5 feet of clayey fine to medium sand, then the concrete floor slab should be specially designed for expansive soil conditions as mentioned above. - - BENTON ENGlrwLRINO. INC. -13- 9. Site Grading - - -~ - - - Presently, the subject site is covered with loose and soft top solls of various thicknesses along with seveml piles of untested loose fills containing trash and large boulders. The loose and soft top soils were found to the depths of 0.5 foot, 1 .O foot and 1 .O t&t in the areas of Borings 1, 2 and 3 respectively, These loose and soft top soils should be entirely excavated at the time of grading and the loose top soils may either be compacted 3 feet below flnished $&de and may b8 replaced by a nonexpansive soils or if nonexpansive these may be recom- pacted within the upper 3 feet. The trash and large size of cobbles found in the existing piles of soils on the site should be removed and disposed of offsite before these piles of soils can be used for compacted ftlls. It is best to use these piles of soils as non-structural fills, In !ho em betw8en the central building and the scuth buildings where new fills are to be placed, The areas to receive the fills should be scarified to 0.5 foot below existing grade, moistened or dried as nec- essary to an optimum moisture content before placement of new fills. It is recommended that all grading opemtions be performed under continuous inspection and be in accordance with the op- plicable sections of the attached Appendix AA entitled, “Standard Specifications for the Place- ment of Compacted Filled Ground.” All new fills to be placed within the subiect property should be compacted to at least 90 percent of the maximum dry density obtained by the A.S.T.M. D1557- 70 method of compaction that uses 25 blows of a 10 pound rammer falling from a height of I8 in- ches on each of 5 layen in a 4 inch diameter meld. Respectfully submitted, BENTON ENGINEERING,INC. BYA&KI 5. H. Shu, Civil Engineer Reviwed by Distr: (5) Addressee il, G.F.D.S. Engineers 1620 Montgomery Street Son Fmncisco, California 94111 Attention: Mr. Ed Dickmann BENTON ENGINEERING. INC. - - - - - - - - - - - - S&V D/EGO GAS 8 ELECJBK COh9PANY EASEMENJ 4 &- PADPtRJY LINE @ Indicates Location of Test Boring DATE: 4-5-73 DRAWN: R.W. SCALE: l”=BO LOCATION OF TEST l.K!Rli~:GZ ARROYO VILLAS CONDOMINIUM EASTERLY OF ALTISMA WAY AND CARINGA WAY CARLSBAD, CALIFORNIA PROJECT NO. 73-3-26A BENTON ENGINEERING, INC. DRATNO N0. - - - - - R 3 - i SUMMARY .sH.EET z< 55 .zc: Q z* us % g; 92, !& BORING NO. 1 WY zix ylx ELEVATION 77.0’ * > Y”E E.t a ‘Pr pj %g Gmy-Brown, Maist, Soft, I\ Mottled With Fine Sandy Clay, CLAYEY Occasional Pockets of Silty Fine to Medium Sand and Silty 6.5 12.8 111.4 FINE Continued on Dmwing No. 3 - Indicates Undisturbed Drive Sample Indicates Loose Bag Sample * - Elevations shown were obtained by Interpolation between contour lines on Tri-State Engineering Company Job No. 010 1557 Sheet I, Doted January 29, 1973. PROJECT NO. I DRAWNG NO. 73-3-26A BENTON ENGINEERING, INC. 2 - - - - - - - - - - - - SUMMARY SHEET BORING Nb. 1 (&,,j) Lenses of Silty Fine Sand GRAVELLY CLAY MEDIUM SANDY AYEY FINE TO -~ - - - - - - - - - t3 > 9. r - 2 4 - PROJECT NO. DRAWING NO. 73-3-26A BENTON ENGINEERING, INC. 4 CLAYEY FINE TO MEDIUM SAND WITH MOTTLED LAYERS OF FINE TO MEDIUM SANDY CLAY 16.; 22.1 14.2 I 5.3 109.; - - - - - - - - - 2 s Lt YE Cd 550 SUMMARY SHEET : gfi ; $2 2 SE; BORING NO. 2 t?u, ELEVATION 80.0' 0 2 -Brown, Very tdaist, sat?, CLAYEY Occasional ?qskets of Silty 0.8 22.0104.2 FINE SAND WITH CLAYEY SILT 24.3 17.6 116.0 - - - - - - - - SUMMARY SHEET BORING NO. 2(COnf) pyjf:gg~ I I DRAWING NO. BENTON ENGINEERING, INC. 6 -. - - - - i - - ‘- > s - f < - SUMMARY SHEET eORlNG NO. 3 ELEVATION 64.0' SANDY CLAY Brown, Moist, Very Firm, Few Coarse Grains CLAYEY FINE Brawn, Moist, Very Compact AND SLIGHTLY SILTY FINE TO MEDIUM SAND Continued on Drawing No. 8 BENTON ENGINEERING INC SUMMARY SHEET BORING NO. 3(cont) PROJECT NO. DRAWING NO. 73-3-26A BENTON ENGINEERING, INC. a CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT I I I l--t--l-l 1. I I IY I IlIll 2 3 ---L- \ . \ . \. 0 INDICATES PERCENT CONSOLIDAlION Al FIELD YO,ST”IE PROJECT NO. 73-3-26A . INDICATES PERCENT CONSOLlDATlON AFTER SATURATION DRAVINB NO. BENTON ENGINEERING, INC. 9 BENTON ENGINEERING, INC. APPLIED SOlI. MECHANICS - FO”NDATIONG - 6717 CONVOl COURT SAN DIEGO. CALIFORNIA 9*111 PHlLlP HENKING BENTON P”L,,DEHT ClYlL ENGINEER APPENDIX AA STANDARD SPECIFICATIONS FOR PLACEMEN OF COMPACTED FILLED GROUND - TELEPHONE (714, 66!%18SS 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 oreas 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 ony unsatisfactory conditions ore 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 oreas to be filled free of vegetotion 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 o 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. k) Where fil Is 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 horizontol 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. - - - -~ - - - - - - ,- - - - - 3. 4. Placirrg, Spreading, and Compacting Fill Materials. 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 I8 inches on each of 5 layers in a 4” diameter cylindrical mald of a 1/30th cubic foot volume. 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 ony other approved sources and by mixi% 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 rights-of-way shall be in accordance with those of the governmental agency havirg jurisdiction. . (4 b) (cl (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 spreadiw to insure uniformity of mate&l at-d 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 compactirrg process. Men the moisture content of the fill material is above that specified by the soils engineer, the fill material shall be aerated by blading and scarifyiw or other satis- factory methods until the moisture content is near optimum as specified by the soils erlgineer. 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 rpecifled density. Rolling shall be acccmpllshed while the fill material is at the specified moisture content. Rolllrg of each layer shall be continuous over Its entire area and the roller shall make sufficient trips to insure that the desired density has been obtained. The entire oreas to be filled 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 roll on the slopes. Compacting of the slopes shall be accomplished by backrollig the slopes In increments of 3 to 5 feet in elevation gain or by other methods producing satisfactory results. - - 0-l - Field density tests shall be taken by the soils engineer for approximately each foot in elevation gafn 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 ewineer . The location 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. Tests shall be taken on corner and terrace lok for each two feet In elevatlon gain. The rolls ergIneer may take additional tests as considered necessary to check on the uniformity of compaction. Where sheepsfoot rollers ore used, the tests shall be taken in the com- pacted material below the disturbed surface. No addi tlonal layers of fill shal I be spread until the ffeld density tests indicate that the specified density has been obtained. - (g) The fill operatlon shall be continued In six inch (6”) compacted layers, as specified above, untfl the fill has been brought to the flnlshed slopes and grades as shown on - the accepted plans. 5. Inspection. Sufflclent inspection by the solls er\gineer.shall be maintained during the - fllllrg and compactfng operations so that he can certify that the fill was constructed in accordance with the accepted specifications. 6. Seasonal Limlk . No fill material shall be placed, spread, or rolled if weather conditions Increase the moisture content above permissible limits. When the work is interrupted by roln, RII operations shall not be resumed until field tests by the soils engineer Indicate that - the moisture content and density of the fi II are as previously specified. 7. Limltlrg 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 nonexpansive. .- a. All recommendotlons presented in the “Conclusions” section of the attached report are a port of these speclftcations. esuraN LULIIYLIIIIICI. INC, - - - - - - - - - - - - - - - - PHlLlP HENKING BENTON PllSIDINT CIYIL LNT,NLE.I1 BEtiTON ENGINEERING. INC. APPLIED BOIL MECHANICS - FO”NDAT,ON* 0717 CONVO” COURT BAN OIEOO. CALIFORNIA 9211, APPENDIX A Unified Soil Classification Chart* SOIL DESCRIPTION GROUP SYMBOL I. COARSE GRAINED, More than half of material is &thon No. 200 sieve size.** GRAVE LS CLEAN GRAVE LS - holf of coarse fraction is larger than No. 4 sieve size but SmallerGRAVELS WITH FINES than 3 inches (Appreciable amount of fines) SANDS CLEAN SANDS -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 materiol is smaller than No. 200 sieve size.** SILTS AND CLAYS Ill. Liquid Limit Less than 50 SILTS AND CLAYS Liquid Limit Greater than 50 HIGHLY ORGANIC SOILS GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT TYPICAL NAMES TLLEP”ONE 171.) ,eJs.,oss Well graded grovels, 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 grovels, poorly graded grovel- sand-cloy mixtures. Well graded sand, gravelly sonds, little or no fines. Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly graded sand-silt mixtures. Clayey sands, poorly graded sond-clay mixtures. Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plasticity. Inorganic cloys of low to medium plas- ticity, gravelly cloys, sandy cloys, silty cloys, lean clays. Organic silts and organic silty-cloys 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 Peat and other highly organic soils. * Adopted by the Corps of Engineers and Bureau of Reclamation in January, 1952. ** All sieve sizes on this chart are U. S. Standard. - BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS - ,=O”HD*T,ON8 6717 CONYOY COURT SAN DIEGO. C*LIFORNI* 0*111 - - - - - - - - - PHlLlP HENKINC) BENTON nr*nor*r ElYlL LN.aI*IIL” TELLS-HONE ,714, 5(1s.,ese APPENDIX B Sompl ing 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 o steel barrel 3.0 inches outside diameter, with a special cutting tip on one end and o 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 o 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, ofter 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 d riving energy is calculated as the overage 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 ore 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 ot selected time intervals - for each increment. Generally, each increment of load is mointoined 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 oddition 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 ore 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.