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HomeMy WebLinkAbout76-3-30AF; Elm Street Extension and Storm Drain Installation; Elm Street Extension & Storm Drain Installation; 1976-04-16PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6717 CONVOY COURT SAN DIEGO, CALIFORNIA 92111 April 16, 1976 TELEPHONE (714) 565-19S5 City of Carlsbad Engineering Department 1200 Elm Avenue Carlsbad, California 92008 Attention: Mr. Joe Spano Gentlemen: This is to transmit to you five copies of our report of Project No. 76-3-30AF, entitled "Soils Investigation, Proposed Elm Street Extension and Storm Drain Installation, Between Valley Street and Donna Drive, Carlsbad, California," dated April 16, 1976. If you have questions concerning any of the data presented in this report, please contact us. Very truly yours, BENTON ENGINEERING, INC. nton, Civil Engineer SOILS INVESTIGATION Proposed Elm Street Extension and Storm Drain Installation Between Valley Street and Donna Drive Carlsbad, California City of Carlsbad Project No. 76-3-30AF April 16, 1976 BENTON ENGINEERING, INC. BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6717 CONVOY COURT SAN DIEGO, CALIFORNIA 92111 PHILIP HENKING BENTON _ „__ PRESIDENT - CIVIL ENGINEER TELEPHONE (714) 56S-1955 SOILS INVESTIGATION Introduction This is to present the results of a soils investigation conducted in the proposed extension section of Elm Street between Valley Street and Donna Drive in Carlsbad, California. It is our understanding that a storm drain and a sewer line will be installed approximately 48 feet below the proposed finished grade of the roadway extension between Valley Street and Monroe Street. It is further understood that the proposed storm drain and sewer line will be installed at a horizontal distance of approximately 10 feet northerly of two existing water mains which are located approximately 5 feet below the proposed finished grade of the roadway surface. The objectives of this investigation are: (1) to determine the general subsurface conditions and certain physical properties of the subsoils at the proposed Elm Street extension between Valley Street and Monroe Street, so that appropriate trenching procedures could be developed for the installation of the storm drain and the sewer line, and (2) to determine the physical characteristics of the subgrade soils immediately beneath the proposed roadway pavement, so that appropriate soil design parameters could be presented for the design thicknesses of the proposed roadway base and pavement. In order to accomplish these objectives, two test borings were drilled at selected locations and both undisturbed and loose soils samples were obtained for laboratory testing. Also, loose samples of the subgrade soils were obtained by hand excavation at two other locations. -2- This investigation was based on the proposed construction plans (Sheets 1 to 7, inclusive) which were prepared by the Engineering Department of the City of Carlsbad under Project No. 74-54. Field Investigation The two borings were drilled, 24 inches in diameter, with a truck-mounted rotary bucket-type drill rig at the approximate locations shown on the attached Drawing No. 1, entitled "Location of Test Borings." The borings were drilled to depths of 50 and 62 Feet below the existing ground surface. A continuous log of the soils encountered in the borings was recorded at the time of drilling and 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 Classification Chart. A simplified description of this classification system is presented in the attached Appendix A at the end of this report. Undisturbed samples were obtained at frequent intervals 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 2100 pounds, and the average drop was 12 inches. The general procedures used in field sampling are described under "Sampling" in Appendix B. Laboratory Tests Laboratory tests were performed on all undisturbed samples of the soils in order to deter- mine the dry density, moisture content, and shearing strength. To determine the shearing strengths of the soils, the soil samples were tested under the normal loads equivalent to their existing overburden pressures which were reduced for water buoyancy for those recovered below water levels. The results of these tests are presented on Drawing Nos. 2 to 8, inclusive. Consolidation tests were performed on representative samples below proposed invert elevations BENTON ENGINEERING, INC. -3- of the storm drain and the sewer line in order to determine the load-settlement characteristics of the soils and the results of these tests are presented graphically on Drawing No. 9, entitled "Consolidation Curves." Direct shear tests were performed on selected undisturbed samples below invert elevations that were all saturated and drained prior to testing. The results of these tests are presented below: Normal Load in kips/sq ft 0.5 1.0 2.0 0.5 1.0 2.0 Maximum Shear Load kips/sq ft 1.65 1.91 4.22 1.78 3.14 3.98 Angle of Internal Friction Degrees 26 40 Apparent Cohesion Ib/sq ft 1420 1370 Boring 1, Sample 12 Depth: 61.0 feet Boring 2, Sample. 11 Depth: 50.0 feet Compaction tests were performed on representative samples of the upper fill soils to establish compaction criteria. The soils were tested according 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 layers in a 4 inch diameter 1/30 cubic foot mold. The results of the tests are presented as follows: Maximum Optimum Mois- Boring Bag Depth Soil Dry Density ture Content No. Sample in Feet Description Ib/cu ft % dry wt 2 2 5.0-6.0 Si I ty fine sand, red brown 123.5 11.0 2 4 15.0-16.0 Clayey fine to medium 129.5 9.4 sand, brown Two R-Value tests were performed on representative subgrade soils in order to determine the soil parameters for pavement design. The tests were performed by Testing Engineers, incorporated of San Diego, and the results are presented on page 4. BENTON ENGINEERING, INC. -4- Depth Below Boring or Existing Ground Soil Tested Sample Location Surface (Feet) Classification "R" - Value Boring 1 12.0-13.0 Silty fine to medium sand 79 with slight clay binder and pockets of fine to medium sand Proposed Elm Street. 0- 1 .0 Silty fine to medium sand 32 Extension at with moderate amount of Station 89+20 clay binder Center Line DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS Soil Strata At Boring 1, a loose silty fine sand topsoil was found in the upper 2.0 feet of the boring. The topsoil was underlain by firm to very firm clayey fine to medium sand soils to a depth of 8.0 feet and then merged to a very firm silty fine to medium sand layer to a depth of 14.0 feet. Between depths of 14.0 feet and 43.0 feet, interbedded layers of compact slightly silty fine to medium sand and compact fine to medium sand were encountered. Between depths of 43.0 feet and 55.5 feet, interbedded layers of very firm clayey fine to medium sand and very firm silty fine to medium sand were encountered. The interbedded layers contained some siltstone fragments. Below 55.5 feet, a very firm siltstone layer was found to 59.0 feet in depth and then merged to very firm silty fine to medium sand to the end of boring at 62.0 feet. White sand lenses were appeared in the soil strata between depths of 55.5 feet and 62.0 feet. Ground water was encountered below a depth of 55.0 feet on March 31, 1976, the day of drilling. At Boring 2, an existing fill was found in the upper 35.0 feet of the boring. The fill soils consisted primarily of medium compact or compact silty sand and clayey sand of various grain sizes except that two loose to medium compact zones were encountered between depths BENTON ENGINEERING, INC. -5- of 4.0 feel- and 7.0 feet and between depths of 13.0 feet and 17.0 feet. Below 35.0 feet, the natural soils consisted of very firm silty fine to medium sand to a depth of 49.8 feet and then merged to very firm siltstone layer to the end of boring at 50.0 feet. Ground water was encountered below a depth of 42.0 feet on April 1, 1976, the day of drilling. Conclusions It is concluded from the results of field investigation and laboratory tests: 1. The soils above proposed invert elevations of sewer pipes and storm drains have favorable strength and consistency characteristics. These soils would provide no particular problems for open excavations if space permits the use of a safe slope ratio or if properly designed shoring is installed in narrow trenches. 2. Ground water was encountered below depths of 59.0 feet and 42.0 feet, respectively, at Borings 1 and 2. Therefore, the proposed storm drains and sewer pipes would be placed below water levels. 3. The soils below the proposed invert elevations have favorable load-settlement characteristics and would provide a good support for the proposed storm drains and sewer pipes from the settlement standpoint. Recommendations 1 . Cut Slopes On Both Sides Of Street Based on the strength characteristics of the tested soil samples, the proposed cut slopes on both sides of the street can be safely constructed up to a maximum height of 35 feet at 1.5 horizontal to 1 vertical slope ratio, and up to a maximum height of 25 feet for a 1 horizontal to 1 vertical slope during construction. BENTON ENGINEERING. INC. -6- 2. Trench Excavations It is understood that the proposed 36 inch diameter storm drains and sewer pipes will be placed at a depth of approximately 48 feet below proposed roadway surface. Therefore, a minimum depth of 48 feet trench will be required. Considering (1) the space limitation for an open excavation, (2) the volumes of earthwork required for an open excavation, (3) the economics of excavations and re compact ion of the open excavation and (4) the presence of ground water above the proposed invert elevations of the pipes, the following two alternatives of trench excavation procedures are suggested: (A) Alternative 1; Trench excavations with anchored sheet piling or a horizontal bracing system: This alternative requires the use of steel sheet piling to protect the trench wall from caving in during construction. The suggested sequences of sheet pile installation and trench excavations are presented below: Step (a): Make open excavations on both sides of the trench in the upper 25 feet of the trench where possible and only in areas where existing utility lines are not in the way. The open excavations may be made at a slope ratio of 1 horizontal to 1 vertical from the existing ground surface to both sides of the trench. The open excavations may be made in sections of 30, 40 or 50 feet in length at a time in order to minimize and to reuse the required sheet pilings. , Step (b): Drill vertical holes, by use of helix auger to the invert elevation along both sides of the trench. The diameter of the holes should be approximately 5 inches less than the widths of the steel sheet piles to be used. The holes should be drilled at alternate intervals not exceeding 1.5 times of the width of each sheet pile. After drilling the vertical holes, steel sheet piles should be driven successively to a depth of at least 12 feet below BENTON ENGINEERING. INC. -7- the proposed invert' elevation. If a high resistance is encountered below the proposed invert elevations, holes may be predrilled to 12 feet below invert elevations to 5 inches less in diameter then the sheet pile to aid in driving to the required depths of penetration. The selected pile section should have a section modulus of at least 39 cubic inch along long axis v/ith an allowable stress of 32,000 pounds per square inches. Step (c): If calculations by the design of shoring requires tie backs, then it is recommended that horizontal holes below the top of sheet piles be drilled at design depths. The horizontal holes are for tie rod installation and should be drilled to a horizontal distance on the order of 35 feet inside of the exposed trench wall. The lengths will depend upon the height above the invert and the horizontal loads to be developed. The horizontal holes should be at least 6 inches in diameter, and drilled at a distance of 6 feet from center to center. After the horizontal holes are drilled, steel tie rods with concrete should be placed in the holes until the concrete has set and gained sufficient strength. Thereafter, concrete deadman, as may be required, shall be constructed at the end of each tie rod. The diameter of the steel tie rod should be at least 2.3 inches in diameter and the deadman should be sized for the assumed design loads. This tie back system may be completely substituted by a horizontal bracing strut or a horizontal jacking system between trench walls at the top of the sheet piles. Step (d): Provide temporary dewatering systems around the sheet pilings. This may be accomplished by drilling deep borings around the sheet piles and to provide a water pump to lower the water levels below invert elevations during construction. To construct the temporary dewatering system, the borings should be drilled at a distance of approximately 5 feet outside of the pilings and be spaced at a distance of not greater than TOO feet. More frequent holes may be drilled as needed. The borings should be drilled to a depth of at least 10 feet below the proposed invert elevations. After drilling, a perforated pipe that is backfilled BENTON ENGINEERING, INC. -8- with a gravel filter should be provided to accommodate wafer pump. The ground water should be lowered below proposed invert elevations by continuous pumping during construction. Step (e): After installation of the sheet piles and lowering of the ground water levels, the trench may be excavated to 2 inches above proposed invert elevations. The remainder of the excavations should then be shaped to accommodate the proper bedding of the pipe. Thereafter, the invert elevations should be uniformly graded to provide a uniform bearing for the pipes. The storm drains and sewer pipes should then be installed. Step (f): Steps (a) to (e) inclusive, may be constructed in a 30, 40 or 50 feet section at a time and then repeated for the next section after pipe installation. (B) Alternative 2; Horizontal Tunnelling This alternative for construction would require open pits to accommodate horizontal auger drilling rigs at a distance of approximately 150 to 200 feet along the proposed trench alignment. The open pits should be excavated and shored with sheet piling as suggested procedures of (a) to (e) inclusive described under Alternative 1 . After open pits are excavated, and dewarering has taken place, a horizontal auger drilling rig may be lowered into the pits for drilling horizontal holes between each two adjacent open pits. The direction and alignment of the horizontal holes should be guided by accurate survey equipment. The steel casing diameter used in the horizontal holes should be large enough (one foot or larger in diameter) to accommodate the sewer pipe and the storm drain with allowance for minor grade adjustments as may be needed and for placing bedding materials at the bottom. The pipes may be installed as horizontal drilling progresses.The space between the pipe walls and the boring walls should then be filled with mortar or concrete soon after pipe installation. Upon completion of one section, the same procedures may be used to install pipes in the next section. BENTON ENGINEERING, INC. -9- 3. Trench Backfilling If Alternative 1 of trench excavation is used, backfilling of trenches should initiate soon after installation of the pipes. After installation of pipelines, pervious backfill materials which conform the following gradations should be placed adjacent to and one diameter in thickness above the pipe: U.S. Sieve Size Percent by Weight Passing 3/4 Inch TOO 3/8 Inch 80-100 No. TOO 0-8 No. 200 0-3 The pervious backfills should be placed in layers to a depth equal to one pipe diameter above the top of the pipe. The pervious backfills should be compacted to at least 85 percent of the maximum dry density per A.S.T.M. D 1557-70 method of compaction. The bedding materials may also consist of the gradations of the pervious backfills. The remainder of the trench should then be backfilled with excavated on site soils that are placed in layers not to exceed 1 foot in compacted thickness and should be uniformly compacted to at least 90 percent of maximum dry density to a depth of 12 inches below the base course materials of the roadway pavement. At least 95 percent of relative compaction should be achieved for the upper 1 foot of compacted fills immediately below the base course materials. If Alternative 2 of trench excavation is to be used, the bedding materials and the pipes should be installed as the drilling progresses.After installation of the pipelines, concrete of sufficient strength should be placed between the top of pipes and the upper periphery of the borings. The concrete may be pumped in by pressure or by injection. The open pits should be backfilled with onsite soils placed in layers not exceeding one foot in thickness and should be uniformly compacted to at least 90 percent of maximum dry density. At least 95 percent of BENTON ENGINEERING, INC. -10- relative compaction should also be attained in all areas of fill and natural soils for the upper 1.0 foot of soils immediately below the base course materials that should be removed and recompacted before pavement construction. 4. Loading On Pipes If trench backfills are placed according to the procedures described under Section 3, "Trench Backfilling" , the 36 inch diameter pipes would subject to an earth load of approx- imately 30,000 pounds per lineal foot. Therefore, special reinforcement of the pipe will be required. 5. Asphaltic Concrete Pavement Sections Using a traffic index of 7.0 and the tested R-Values at the proposed subgrade elevations, the following asphaltic concrete pavement sections may be used: Elm Street Between Elm Street Between Valley Street and Monroe Street and Monroe Street Donna Street a) Asphaltic Concrete Surface 3 3.5 b) Base Course Materials 6 10.0 c) Excavated on site soils compacted to 12 12.0 at least 95 percent of maximum density The base course materials may consist of gravel, well-graded sand, disintegrated granite or crushed rock and conform to the following gradation: U.S. Standard Sieve Size Percent By Weight Passing 2 Inches 100 1 1/2 Inches 90-100 3/4 Inch 50-85 No. 4 25-45 No. 10 15-40 No. 30 10-25 No. 200 Sieve 2-9 In addition, the base course materials should have a minimum R-Value of 70 at 95 percent relative compaction per A.S.T.M. D 1557-70 method of compaction. This method BENTON ENGINEERING, INC. -11- of compaction requires the use of 25 blows of a 10 pound rammer falling from a height of 18 inches on each of 5 layers in a 4 inch diameter, 1/30 cubic foot compaction mold. ) 6. Locations of Underground Utility Lines It is contractor's responsibilty to determine the exact locations of the existing underground utility lines before excavations at the site. ) Respectfully submitted, BENTON ENGINEERING, INC. By ^ S. H. Shu R.C.E. No. 19913 Reviewed by* Philip H. B^nton, Civil Engineer R.C.E. No. 10332 Distr: (5) Addressee SHS/PHB/mr BENTON ENGINEERING. INC. o o (J o u o o u u 8", o m 0 0. 8' 5 «r c"» 3 * q "5._( ^>(t> f SEIf3 £n Q S §Q r-8 rmQm Z I <Q 8 >Tl 2O Zo cP 7* -jo) m oo§oz o-n m CO CDo 5 Zo CO m Z £z om §O >m 5«"s: ) s mO 1- UlUIu. I Q.UIO 0 — 9 3 4- 5 6- 7- 9- 10- 11- 12- 13 14- 15- -SAMPLENUMBER© © 1 SOILCLASSIFICATIONSYMBOL1 I SUMMARY SHEET BORING NO. 1 ELEVATION 192.00-* Brown, Dry, Loose, Topsoil Moist Red Brown, Moist, Firm, with Pockets and Lenses of Fine to Medium Sand Very Firm Red Brown and Gray Brown, Moist, Very Firm, with Slight Clay Binder, and Occasional Pockets of Fine to Medium Sand SILTY FINE SAND CLAYEY FINE TO MEDIUM SAND (Merges) SILTY FINE TO MEDIUM SAND Brown and Yellow Brown, SLIGHTLY SILTY Moist, Compact FINE TO MEDIUM SAND Continued on Drawing C*\ Indicates Undisturbed Drive Sample DRIVE ENERGYFT. KIPS/FT.8.5 14.8 10.6 No. 3 FIELDMOISTURE% DRY WT.9.7 9.4 5.9 DRY DENSITYLBS./CU. FT.110.3 110.5 101.7 SHEARRESISTANCEKIPS/SQ. FT.1.12 1.91 2.03 Indicates Loose Bag Sample * Elevations were obtained by interpolation of the existing ground surface line shown on Sheet 3 of Drawing No. 132-4D prepared by the Engineering Department of City of Carlsbad . PROJECT NO DRAWING NO. -,, ~ onAC BENTON ENGINEERING, INC. 976-3-30AF *• CD O EPTH/FEETQ 15 16 17- 18- 19-. 20^ - 21- 22- 23- 24- 25- 26- 27- 28 _. 29- — 30- - 31 32- 34 3.5 36-SAMPLE INUMBERiT) ^ (5} ^ (£)^ (7^)SOIL !SSIFICATION!SYMBOL Iu^\§§!iv!§S< ^8§i^w N§P| 111 ili$ V<^\V^ 111 111 $v§x ;^^^§S& ^X^'vXNX ^• •. '•' : •' •':' ; SUMMARY SHEET BORING NO. ' Cont. Brown and Yellow Brown, Moist, Compact Gray Brown, Moist, Compact, Little Micaceous Brown, Moist, Compact, with Intermerging Lenses of Silty Fine to Medium Sand Gray Brown, Moist, Compact, Little Micaceous Lense of Silty Fine Sand Light Brown Few Gravel to 1 Inch Moist, Compact, Little SLIGHTLY SILTY FINE TO MEDIUM SAND FINE TO MEDIUM SAND SLIGHTLY SILTY FINE TO MEDIUM SAND (Merges) FINE TO MEDIUM SAND VE ENERGYr. KIPS/FT.cc"-Q 10.6 10.6 12.2 12.2 FIELD/IOISTURE'• DRY WT.3 5 9 5 .3 .1 .2 .4 Y DENSITYBS./CU. FT.D^ 100.4 102.4 110.1 94.7 SHEARESISTANCEIPS/SQ. FT.tt* 2.56 2.75 4.62 3.75 Micaceous PROJECT NO. 76-3-30AF Continued on Drawing No. 4 BENTON ENGINEERING, INC. DRAWING NO 3 UJs mO K 1^DEPTH/FEET37 38- 39- 40_ 41- 42- 43 44 _ 45- 46 47- 48 49- 50- 51- 52 53- 54- J 56- 57-SAMPLENUMBER© @ ©SOILCLASSIFICATIONSYMBOLi H vVater ^^i SUMMARY SHEET BORING NO. ' Cont. Light Brown, Moist, Compact, Little Micaceous With Lenses of Slightly Silty Fine Sand G Le -ay, Moist, Very Firm, with nses of Siltstone Gray, Moist, Very Firm, Little Micaceous 1 Gray, Moist, Very Firm, with Dark Brown Silt Stone Lenses Gray, Moist, Very Firm, with Some Clay Binder Below 54 Feet Brown, Very Moist Saturated Gray, Saturated, Very Firm Co PROJECT NO. 76-3-30AF FINE TO MEDIUM SAND CLAYEY FINE TO MEDIUM SAND SILTY FINE TO MEDIUM | CLAYEY FINE TO MEDIUM SAND SILTY FINE TO MEDIUM SAND SILTSTONE ntinued on Drawing DRIVE ENERGYFT. KIPS/FT.13.3 24.4 39.9 FIELDMOISTURE% DRY WT. |5 31 .6 .5 12 .8 25.4J47 Mo. 5 BENTON ENGINEERING, INC. .3 DRY DENSITYLBS./CU. FT.93.5 92.2 116.3 73.9 SHEARRESISTANCEKIPS/SQ. FT.3.89 7.45 7.09 3.37 DRAWING NO. 4 E I i o i/>i_ D 'o U mO H LU UJU. I Q. HI 5? 58- 59- 60- 61- -SAMPLENUMBER©SOILCLASSIFICATIONSYMBOL11 1 O £l u^ ^ i_! SUMMARY SHEET 2i£ 0SJ5 *": **"-. ^ W J Z *^ << 4 rt BORING NO. 1 Cont. uii ^> gcj ^Hjg H'. *^-O^ V^" t/5^Q^ ^L_ «C^O 1- CO UJE£ s- §^ - Gray, Saturated, Very Firm SILTSTONE Gray, Saturated, Very Firm, with Pockets and Lenses of White Sand Below 59 Feet Jj! ' ,-p......FINETO MEDIUM 34^3 15<3 ni 5 7-45 SAND PROJECT NO. DRAWING NO. 76-3-30AF BENTON ENGINEERING, INC. 5 CDo HUJUJu. I1-Q- UJ 8 ]: 2_ 3- 4- 5- 6- 7 8- 9- 10- 11- 12- 1 Q 14- 15- 16- 17- 18- 19- 20-SAMPLENUMBERhi • 3 | 1 J SOILCLASSIFICATIONSYMBOL1 SUMMARY SHEET BORING NO. 2 ELEVATION 168.4 Red Brown and Light Gray, Me fn Co >ist, Medium Compact to mpact, with Occasional bble to 4 Inches Red Brown, Moist, Loose to Medium Compact Light Gray, Moist, Medium Compact to Compact Brown and Red Brown, Moist, Loose to Medium Compact Medium Compact to Compact Con PROJECT NO. 76-3-30AF CLAYEY FINE TO MEDIUM SAND SILTY FINE SAND CLAYEY FINE TO MEDIUM SAND tinued on Drawing Is DRIVE ENERGYFT. KIPS/FT.4.3 1.1 4.3 1.1 Jo. 7 FIELDMOISTURE% DRY WT.10.8 6.3 12.3 14.6 DRY DENSITYLBS./CU. FT.100.3 94.9 118.2 112.9 UJ jj — (/) -^^ tti 0.88 1.00 2.88 2.14 Fll.L DRAWING NO. BENTON ENGINEERING, INC. 6 Q. LU Q 2Q -"0- Z O ° SUMMARY SHEET BORING NO. 2 Cont . * ecu.o ^ (/)CC CQO 21- 22- 23- 24- 25- 26- 27- 28- 29- 30- 31- 33- 34- 35- 36- 37- 38- 39- 40-] Brown and Red Brown, Moisf, Medium Compact to Compact :% OvxN •\.x X\X ^ Dark Brown, Moist, Compact, Few Roots to 22 Feet PI.Mottled with 20 Percent Red Brown Clayey Fine to Medium Sand $S&N^.^> 7 e) Dark Gray Brown, Moist, Compact, Mottled with Clayey Fine Sand 5S?§^KK\X-VK ^Light Gray, Moist, Compact ^ Light Gray, Moist, Very Firm §§§§ CLAYEY FINE TO MEDIUM SAND 10.6 9.6 125.8 5.28 10.6 9.9 113.1 4.51 SILTY FINE SAND FILL 16.3 14.1 113.2 4.35 SILTY FINE SAND SILTY FINE TO MEDIUM SAND 16.8 10.2 107.2 5.24 SILTY FINE TO MEDIUM SAND 33.3 12.7 118.7 7.40 Continued on Drawing No. 8 PROJECT NO. 76-3-30AF BENTON ENGINEERING, INC. DRAWING NO. 7 H UJ UJLL I 0. UJQ UJ OC_iui Z u SUMMARY SHEET BORING NO. ^ Cont. Z tfl Si *u- OQ S UJ <Z co O 41- 42- 43- 44- 45- 46- 47~ 48- 49- 50 Light Gray, Moist, Very Firm Saturated Gray, Saturated, Very Firm 22.2 14.9 116.8 7.45 SILTY FINE TO MEDIUM SAND 33.3- 18.6-n3.l--6.30 SILTSTONE PROJECT NO. 76-3-30AF BENTON ENGINEERING, INC. DRAWING NO. 8 CONSOLIDATION CURVES eus•t a 0.4 LOAD IN KIPS PER SQUARE FOOT 0.6 0.8 1.0 2 4 8 10 Boring 1 Sample 12 Depth: 61' Boring 2 Sample 10 Deprh: 44' o Indicates percent consolidation at field moisture © Indicates percent consol idation after saturation PROJECT WO. 76-3-30AF BENTOM ENGINEERING, INC. DRAWING NO. 9 o o BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6717 CONVOY COURT SAN DIEGO, CALIFORNIA 92111 PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER TELEPHONE (714) 565-1955 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 tests so that the proposed structures O rnay 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. Q 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 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- O 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 O 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, Q 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. O 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-1557-70 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 l/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 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 having jurisdiction. 4. Placing, Spreading, and Compacting 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 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. (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 scarifying 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-1557-70 modified as described in 2 (d) above. Compaction shall be accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other "approved types of compaction1 equipment, such as vibratory equipment that Is specially designed for certain soil types. Rollers shall be of such design that they will be able BENTON ENGINEERING, INC. o APPENDiX AA - 3 - O to compact the fill material to the specified density. Polling shall be accomplished while the fill material is at the specified moisture content. Rolling 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 areas to be filled shall Q be compacted. (e) Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equip- ment. Compacting operations shall be continued until the slopes are stable but not too dense for planting and until there Is no appreciable amount of loose soil on the slopes. Compacting of the slopes shal! be accomplished by backrolling the slopes in ^ Increments of 3 to 5 feet In elevation gain or by other methods producing satisfactory results. (f) 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 O between tests. Field density tests may be taken at intervals of 6 Inches in elevation gain if required by the soils engineer. The location of the tests In plan shall be so spaced to give the best possible coverage and shal! be taken no farther apart than TOO feet. Tests shall be taken on corner and terrace lots for each two feet In eleva- tion gain. The soils engineer may take additional tests as considered necessary to O check on the uniformity of compaction. Where sheepsfoot rollers are used, the tests shall be taken in the compacted material below the disturbed surface. No additional layers of fill shall be spread until the field density tests Indicate that the specified density has been obtained. Q (g) The fill operation shall be continued In s!x Inch (6") compacted layers, as specified above, until the fill has been brought to the finished slopes and grades as shown on the accepted plans. 5. Inspection. Sufficient Inspection by the soils engineer shall be maintained during the fill- ing and compacting operations so that he can certify that the fill was constructed in accord- ^ ance with the accepted specifications. 6. Seasonal Limits. No fill material shall be placed, spread, or rolled if weather conditions Increase the moisture content above permissible limits. When the work is interrrupted by rain, fill operations shall not be resumed unti! field tests by the soils engineer indicate that O the moisture content and density of the fill are as previously specified. 7. All recommendations presented In the "Conclusions" section of the attached report are a part of these specifications. 0 PHIUP HENKING BENTON PRESIDENT - CIVIL. ENGINEER BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6717 CONVOY COURT SAN DIEGO, CALIFORNIA 92111 APPENDIX A Unified Soil Classification Chart* SOIL DESCRIPTION '• COARSE GRAINED, More than half of material is larger than No. 200 sieve GROUP SYMBOL TYPICAL NAMES TELEPHONE (714) S6S-195S size.' GRAVELS CLEAN GRAVELS More than half of coarse fraction is larger than No. 4 sieve size but smaller GRAVELS WITH FINES than 3 inches (Appreciable amount of fines) SANDS More than half of coarse fraction is smal ler than No . 4 sieve size CLEAN SANDS SANDS WITH FINES (Appreciable amount of fines) IL 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 HIGHLY ORGANIC SOILS GW Well graded gravels, gravel-sand mixtures, little or no fines. GP Poorly graded gravels, gravel-sand mixtures, little or no fines. GM Silty gravels, poorly graded gravel- sand-silt mixtures. GC Clayey gravels, poorly graded gravel - sand-clay mixtures. SW Well graded sand, gravelly sands, little or no fines. SP Poorly graded sands, gravelly sands, little or no fines. SM Silty sancls, poorly graded sand-silt .mixtures. SC Clayey sands, poorly graded sand-clay mixtures. ML Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plasticity. CL Inorganic clays of low to medium plas- ticity, gravelly clays, sandy clays, silty clays, lean clays. OL Organic silts and organic silty-clays of low plasticity. MH Inorganic silts, micaceous or diatornaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity PT 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 FOUNDATIONS PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER 6717 CONVOY COURT SAN DIEGO, CALIFORNIA 92111 APPENDIX B TELEPHONE (714) 565-1958 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 rate of deformation is equal to or less than 1/10000 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 stops. The dial reading is recorded and expansion is recorded until the rate of upward movement is less than 1/10000 inch per hour.