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Home My WebLink About3184; CANNON ROAD WEST; GEOTECHNICAL INVESTIGATION; 1997-01-23& LEIGHTON AND ASSOCIATES, INC. Geotechnical and Environmental Engineering Consultants GEOTECHNICAL INVESTIGATION, PROPOSED GOLF CART UNDERCROSSINGS, CANNON ROAD AND HIDDEN VALLEY ROAD, CARLSBAD, CALIFORNIA January 23, 1997 Project No. 4930489-013 I. Prepared For: CARLTAS COMPANY 5600 Avenida Encinas, Suite 100 Carlsbad, California 92008-4452 3934 MURPHY CANYON ROAD, SUITE 13205, SAN DIEGO, CA 92123 (619) 292-8030• (800) 447-2626 FAX (6 19) 292-0771 January 23, 1997 Project No. 4930489-013 To: Carltas Company 5600 Avenida Enemas, Suite 100 Carlsbad, California 92008-4452 Attention: Mr. Charlie Kahr Subject: Geotechnical Investigation, Proposed Golf Cart Undercrossing, Cannon Road and Hidden Valley Road, Carlsbad, California Introduction In accordance with your request, we have performed a limited geotechnical investigation at the site of the proposed Golf Cart undercrossings beneath Cannon Road and Hidden Valley Road in Carlsbad, California (see Site Location Map, Figure 1, page 2). The undercrossings will be located at Station 43+00 and Station 43+90 of Cannon Road and Hidden Valley Road, respectively. Leighton and Associates j (Leighton) has previously performed geotechnical investigation for the Cannon Road Golf Cart undercrossing at Station 27+00 and for the Armada Drive Golf Cart undercrossing at Station 3+60. As part-of our study, we have reviewed the referenced reports and plans. Proposed Undercrossing We understand the proposed undercrossings will consist of aluminum structural plates with a width of 15 feet 4 inches, a height of 10 feet and a thickness of 0.125 inches. The Cannon Road tunnel will be 184 feet in length and the Hidden Valley Road tunnel will be 155 feet in length. The arches will be provided with cover of approximately 7 to 10 feet of compacted soil backfill. The base of the structures will be at approximate elevations of 157 and 166 feet mean sea level (msl) for the Cannon Road and Hidden Valley Road tunnels, respectively. It is proposed to install the structural plate undercrossing in an open excavation and place compacted backfill to achieve design grades. Site Investigation r Our site investigation consisted of the excavation of two exploratory borings; one at the Cannon Road location and one at the Hidden Valley Road location. These borings were drilled to depths of 5 to 10 feet below the tunnel invert elevation. Boring B-i was excavated at Station 43+90 on Hidden Valley Road to a depth of 40 feet below existing grade. Boring B-2 was excavated at Station 43+00 on Cannon Road to a depth of 27 feet below existing grade. Both borings were backfilled upon I I \ 1 PROJECT SITES Sbb Base Map: Thomas Bros. GeoFinder for Windows, San Diego County, 1995, Page 1126 CARLTAS COMPANY SITE Golf Cart Undercrossings Hidden Valley Road LOCATION and Cannon Road Carlsbad, California MAP 0 2000 4000 I I Approximate Scale in Feet Project No. 4930489-013 TT Date 1042 889 1-27-96 Figure No. I 4930489-013 completion. The boring logs are attached as Appendix B. The approximate boring locations are indicated on Figures 2 and 3, Boring Location Maps. Geologic Conditions Hidden Valley Road As observed in Boring B-i, the area is underlain by a thin veneer (approximately 2 feet thick) of fill soils, underlain by Quaternary terrace deposits consisting of dense silty sands and at depth (pipe invert elevation) very dense silty sandstone to fine sandy, clayey .siltstone of the Santiago Formation at depth. No ground water seeps were encountered in this boring at the time of our drilling. We anticipate that the bedrock soil conditions will be similar at both ends of the tunnel. However, we anticipate that potentially compressible colluvial materials overlie the bedrock in the vicinity of the eastern end of the tunnel. Due to inaccessibility, we were unable to evaluate the exact extent of the colluvium. During grading, the project geologist should observe the tunnel excavation in this area and evaluate required removal depths if necessary. Cannon Road As observed in Boring B-2, this area is underlain by dense Terrace Deposits. The Terrace Deposits consist of orange-brown to pale gray, damp to moist, dense silty sands. Practical refusal was encountered at a depth of 27 feet below ground surface (bgs) on cobbles/rock materials. These materials are not anticipated to be encountered at the proposed tunnel invert given their depth. Faulting and Seismicity Our discussion of the faults on the site is prefaced with a discussion of California legislation and state policies concerning the classification and land-use criteria associated with faults. By definition, of the JCalifornia Mining and Geology Board, an active fault is a fault which has had surface displacement within Holocene time (about the last 11,000 years). The State geologist has defined a potentially active fault as any fault considered to have been active during Quaternary time (last 1,600,000 years). This definition is used in delineating Earthquake Fault Zones as mandated by the Alquist-Priolo Earthquake Faulting Zone Act of 1972 and as subsequently revised in 1974, 1975, 1976, 1979, 1990, 1991, 1992, and 1993. The intent of this act is to assure that unwise urban development does not occur across the traces of active faults. The subject site is not located within any earthquake fault zones as created by the Aiquist-Priolo Act (Hart, 1994). Our review of available geologic literature indicated that there are no known active or potentially active faults that transect Carlsbad Ranch. However, inactive fault zones were encountered in a number of places within and adjacent to Carlsbad Ranch during previous investigations. Inactive fault zones were encountered in the cut slope along the north side of Palomar Airport Road during previous geotechnical j work performed at the site (Geotechnics, 1992) and in the eastern portion of the site (Weber, 1982 and Leighton, 1991 and 1992). 4930489-013 The location of the proposed development can be considered to lie within a seismically active region, as can all of Southern California. The Rose Canyon Fault Zone which is located approximately 3.5 miles to the west of the site is considered to have the most significant seismic effect at the site from a design standpoint. A maximum probable earthquake of moment magnitude 6.25 on the fault could produce a peak horizontal ground acceleration of approximately 0.30g at the site. For design purposes, an effective ground acceleration of 0.40g based on the Uniform Building Code criteria (ICBO, 1994) may be assumed. Seismic Considerations The principal seismic considerations for most structures in Southern California are surface rupturing of fault traces, damage caused by ground shaking and/or seismically induced liquefaction or dynamic settlement. Theprobability of damage due to ground rupture is considered minimal since active faults are not known to cross the site. Ground lurching. due to shaking from distant seismic events is not considered a significant hazard, although it is a possibility throughout. the Southern California region. Ground Shaking The seismic hazard most likely to impact the site is ground shaking resulting from an earthquake on one of the major regional faults. As discussed above, a maximum credible event on the Rose Canyon Fault Zone (considered the design earthquake for this site) could produce a peak horizontal bedrock acceleration at the site of 0.30g and an effective ground acceleration of 0.40g. Liquefaction/Dynamic Settlement Liquefaction of cohesionless soils can be caused by strong vibratory motion due to earthquakes. Research and historical data indicate that loose granular soils underlain by a near-surface ground water table are most susceptible to liquefaction, while the stability of most silty clays and clays is not adversely affected by vibratory motion. Due to the relatively dense nature of the onsite Terrace Deposits and Santiago Formation and the absence of a near surface ground water table, the potential for liquefaction on the site due to the design earthquake is anticipated to be very low. Laboratory Testing Representative samples of the soils encountered were obtained for laboratory testing. Samples were obtained at the approximate invert of the proposed structures and were tested to evaluate the engineering characteristics of the onsite soils. For soil-bearing values, the soils were judged to be similar to those previously tested during previous investigations of the Carlsbad Ranch. The chemical characteristics of the soils are as follows: -4- 4930489-013 ) Hidden Valley Road Undercrossing: Sample B-I at 22 to 25 feet pH-7.6 Soluble Sulfate Content - <0.005% (negligible sulfate attack per tJBC, 1994) Minimum Resistivity - 380 ohm-cm (severe corrosion potential) Chloride Concentration - 500 ppm = 0.05% (moderate corrosion potential) Cannon Road Undercrossing: Sample B-2 at 22 to 25 feet pH - 7.9 Soluble Sulfate Content - <0.005% (negligible sulfate attack per UBC, 1994) Minimum Resistivity - 7,700 ohm-cm (low corrosion potential) Ch1oride Concentration - 500 ppm = 0.05% (moderate corrosion potential) -.5- 4930489-013 CONCLUSIONS AND RECOMMENDATIONS It is our opinion, the site is suitable to receive the proposed improvements provided the results of this report, project plans, and manufacturer's specifications are adhered to. Hidden Valley Road Undercrossing The results of the geotechnical testing obtained for the Hidden Valley Road undercrossing are not within the acceptable range specified by the manufacturer nor the Caltrans Highway Design Manual. Accordingly, we recommend that an import source be used to backfill this undercrossing. The soils within 5 feet of the bottom of the proposed footings and sides of the proposed undercrossing should be removed and replaced with an import source. This should include removal of the colluvial soils at the eastern end of the tunnel. The import source should be tested and approved by the geotechnical consultant prior to construction. The import soils should have an expansion index less than 50 (per UBC 18-2), have a pH from 5.5 to 8.5, have no sizes greater than 3 inches in maximum size, and have a minimum resistivity greater than 1,500 ohms-cm. Import backfill soils should be compacted to a minimum relative compaction of 95 percent (per ASTM D1557-91). It is our opinion that a source of suitable backfilled material can be obtained on site. Due to the impermeable characteristics of the native soils in the Hidden Valley Road tunnel area and the anticipated use of a granular, free draining material for backfill, we recommend that a subdrain be installed at the bottom of the tunnel excavation (below the invert of the pipe). The subdrain should consist of a 4-inch diameter, Schedule 40 perforated pipe, encased in a minimum of 3-cubic foot of clean 3/4-inch gravel, wrapped in Mirafi 140N geofabric or equivalent. The subdrain should daylight out at the east end (lower end) below the tunnel. Cannon Road Undercrossing The results of the geotechnical testing obtained for the Cannon Road Undercrossing are within acceptable range for backfill soils as stated in the brochure provided by the manufacturer of the Aluminum Structural Plate (Contech, 1991) and the Caltrans Highway Design Manual. We recommend, however, that the manufacturer review, the results of this testing to verify that the chemical characteristics are within acceptable ranges. We also recommend that the manufacturer review the chloride test results to evaluate if. the undercrossing needs a protective coating due to the corrosive chloride environment. For backfill of the Cannon Road undercrossing, the onsite granular soils may be utilized. All backfill on the sides and within 2 feet of the top of pipe should be compacted to a minimum of 95 percent (per ASTM D1557-91). Backfill adjacent to the structure should be compacted with lightweight compaction equipment. All backfill should be placed above the optimum moisture content of the soil. Soil placed from finish grade to within 2 feet of the top of pipe should be compacted to 90 percent as should the pipe bedding area (see Figure 4, Backfill Detail). Backfill soils should be tested to verify conformance with the manufacturer's specifications regarding chemical characteristics. -6- 4930489-013 General Recommendations If utility trenches are proposed over the top of the arch, we recommend that the trenches be backfihled with lightweight hand operated compaction equipment (i.e. wacker) within 5 feet of the top of the arch. For design purposes, a soil-bearing value of 3,000 pounds per square foot may be utilized assuming 1/2-inch of settlement for footings at least 12 inches below tunnel invert level. Some zones of relative cohesionless soils may be encountered during excavation. Therefore, the stability of temporary slope should be evaluated during construction by the geotechnical consultant. All slopes should be constructed in accordance with OSHA guidelines. In general, we recommend that the excavation be laid back at an inclination of no steeper than 1:1. Representatives of Contech stated that an equivalent aluminum corrosion rate of 0.5 mil per year may be utilized (Army Corps of Engineers Study) for non-corrosive soils. This is roughly equivalent to a time to perforation of 250 years for an aluminum thickness of 0.125 inches. Approximately 2 feet of backfill is to be placed at the inside base of the undercrossing to provide a pavement subgrade. The backfill soils should consist of granular soils with a very low to low expansion potential (a less than 50 per UBC .18-2). In order to avoid an accumulation of water, we recommend a subdrain be installed at the low point of the structure. The subdrain should consist of a minimum of 1-cubic foot of clean 3/4-inch gravel wrapped in Mirafi 140N geofabric or equivalent and outlet into a stonndrain or some other collective drainage system. As an alternative, a linear slotted drain may be used at both entrances to the tunnel to intercept surface water provided all tunnel joints are waterproof. Pursuant to our investigation for previous undercrossings (Cannon Road and Armada Drive), the City of Carlsbad expressed concern over the deflection of the arch(s) that may occur as part of site construction. Therefore, we recommend the implementation of a monitoring program during site construction.. This should include monitoring during construction to verify that the observed deflections are within 2 percent of the deflections in accordance with ASTM D798-88 (shape control). Duringinstallation, we recommend that the contractor implement a deflection monitoring program that can be monitored continuously throughout the construction process by the contractor, civil and geotechnical engineer and representative of the City of Carlsbad. In addition, the top of the arch should be surveyed at various locations by the project civil engineer prior to and during backfilling operations. All backfill operations shall be performed to comply with the relative compaction recommendations stated in Figures 4 and 5. After backfill operations are complete and prior to installation of utilities above the arch, we recommend that load testing of the arch be performed. The arch should be loaded to design loading (H-20) and monitored for deflection by the City inspector, civil and geotechnical engineers. The civil engineer will provide tolerable limits for deflection of the proposed utilities on the project plans. Should these deflections be exceeded, additional recommendations to protect the proposed utilities will -7- 0 4930489-013 be warranted. If measured deflections are within acceptable tolerances, installation of the proposed utilities may proceed after written approval is received. It may also be desirable to design all construction seams as watertight joints to minimize the potential for future seepage-related problems. During consction'of the undercrossing, continuous observation and testing of the backfill process should be performed. In addition, prior to backfill, the chemical characteristics of the proposed backfill soils should be tested prior to use to assure conformance with the project specifications and the recommendations provided herein. If you have any questions regarding our report, please contact this office. We appreciate this opportunity to be of service. Respectfully submitted, LEIGHTON AND ASSOCIATES, 9 (Ex co 0 0 Z Jose eG. Franzone, RC 9 No. 39 In Michael R. Stewart~ G 1349* (Exp. 12/31/97) ector of Engineering cc Z Directory of Geology SCB/JGFIMRS/jss Attachments: Figure 1 - Site Location Map Figure 2 - Boring Location Map Figure 3 - Boring Location Map Figure 4 - Typical Backfill Detail, Cannon Road Undercrossing Figure 5 - Typical Backfill Detail, Hidden Valley Undercrossing :. Appendix A - References .. Appendix B - Boring Logs ED G4,04 Distribution: (2) Addressee .8 0 (2) Hunsaker and Associates Q: Attention: Mr. Jeff Mitchell No. 349 CERTIFIED ENGINEERING LP ~A GEOLOGIST OF CA -8- U --- - I - - I J I 4 hfti1 - MEN W-41 a N~Wm A I' I!SJI? A LEGEND I B-2 Approximate boring location TD2T with total depth indicated ! SR.00KS 18x1e,# eR.ATc' fl4LT I /.8 AR.Nco OR. EQUAL SWTTE.D DRIJ BORING LOCATION MAP Golf Cart Undercrossings Hidden Valley Road and Cannon Road Carlsbad, California Project No. _4930489-013 • Scale • 4 0 I Engr IGeol JGFIMRS II Ej_J Drafted By KAM 104588 • flsltA •: •. tin 9 q•i Pedestrian Underpass L 43+00 Cannon Road H. XMCO OK EQUAL SLOTTED 1KAt 1609 1! docs is 15 KATe.D INLET ••- '•- I. 1Ior,cc Z TO DA1Lk44T j H : Project No. 4930489-013 Scie 1'40' Enar.IGeoL JGF/MRS Drafted By KAM 1045 W9 - Date 12796 Fi9Ize No.3 See Figure No. 2 for Legend, BORING LOCATION MAP Golf Cart Undercrossings; Hidden Valley. Road and Cannon Road Carlsbad, California I RR BACKFILL AREA --ALUMINUM STRUCTURAL PLA1E PIPE ARCH 960/0 MIN. Elm RELATIVE RELATIVE 1:1 TEMPORARY CUT SUBDRAIN (SE TX11 NATIVE SOIL OR I- C NEUTRAL SAND BACKFILL cOMPPCTEDFLL \ BEDDING AREA MIN. SO% R.C. AREATOBEJETTEDWTTH SELECT IAL MATERIAL SHALL BE APPROVED BY SOILS ENCHNEER PRIOR TO JETTiNG I Project No. 4930489-013 - TYPICAL BACKFILL DETAIL Scale No scale II Canyon Road Undercrosszng Engr/Geol JGF/MRS Drafted By KAM 1042 889 Date 1-23-96 Figure No. 4 _ NATIVE SOIL UNACCEPTABLE FOR USE AS BACKFILL IMPORT SOURCE 1___— RULAR BACKFILL AREA TO BE APPROVED ByOEOT4ICA1. t AT 90% MIN. R. CONSULTANT PRIOR TO BKFLL.-ALUMINUM STRUCTURAL PLATE PIPE ARCH 96% MN. 96% MN. RELATIVE RELATIVE -, 6'O SUBDRAIN 1•4" (SEE TCT 4 6'- 1" NEUTRAL SAND BACKFILL 14 90%MIN. 2% Pt - 4" DIAMETER, SCHEDULE 40, PERFORATED PVC [J AREA TO BE JETTED WITH SELECT MATERIAL WITH 3 CUBIC FEET OF CRUSHED AGGREGATE MATERIAL SHALL BE APPROVED BY SOILS PER FOOT WRAPPED IN MIRAPI I40N OR EQUIVALENT, ENGINEER PRIOR TO JETTING DISCHARGE TOASUITABLE OUTLET. Project No. 4930489-013 TYPICAL BACKFILL DETAIL Scale No scale Engr~ U FMRS ; Hidden Valley Road Undercrossing 1042 889 Date 1-23-96 Figure No. 5 ..&. - . . A-i 4930489-013 APPENDIX A California, Department of Transportation, 1990, Highway Design Manual, dated July 1, 1990. Contech, 1991, Construction Products, Inc., 1991, Aluminum Structural Plate. Hart, E.W., 1992, Fault-Rupture Hazard Zones in California, Alquist-Pnolo Special Studies Zones Act of 1972 with Index to Special Study Zones Maps: Department of Conversation, Division of Mines and Geology, Special Publication 42. International Conference of Building Officials, .1994, Uniform Building Code. Leighton and Associates, Inc., 1995a, Proposed Undercrossing, Cannon Road and Armada Drive, Carlsbad Ranch, Phase I, Carlsbad, California, Project No. 4930489-09, dated June 13, 1995. 1995b, Geotechnical Investigation, Proposed Golf Cart Uñdercrossing, Cannon Road, Carlsbad, California, Project No. 4930489-09, dated April 26, 1995. 1993, Preliminary Geotechnical Investigation, Units I and II (Lots 1 through 7), Carlsbad Ranch Phase I, Carlsbad, California, Project No. 4930489-01, dated July 22, 1993. ,1992, City of Carlsbad Geotechnical Hazards Analysis and Mapping Study, 84 Sheets, dated November, 1992. 1991, Supplemental Geotechnical Evaluation, Proposed College Business Park, Carlsbad 1 . . Tract 85-17, Carlsbad, California, Project No. 8841363-04, dated January 16, 1991 revised j September 24, 1991. ,No Date, Waterproofing of Cannon Road and Armada Drive Undercrossing, Carlsbad Ranch, Carlsbad, California, Project No. 4930489-008. Weber, 1982, Recent Slope Failures, Ancient Landslides and Relation Geology of the North-Central J . Coastal Area, San Diego County, California, California Division of Mines and Geology, Open File Report 82-12, LA. I GEOTECHNICAL BORING LOG KEY Date Sheet 1 of 1 Project KEY TO BORING LOG GRAPHICS Project No. Drilling Co. Type of Rig Hole Diameter Drive Weight Drop in. Elevation Top of Hole +1- ft. Ref. or Datum cc 0 > +. CL CO •o.o . .0 4d..J .,- 0 Z ! E 30 o 00Q. L . c'.. 0 " _W C.' —d U : w GEOTECHNICAL DESCRIPTION Logged By Sampled By 0 — - - CL Inorganic clay of low to medium plasticity; gravelly clay; sandy clay; silty clay; lean clay CH Inorganic clay of high plasticity; fat clay OL-OH Organic clay, silt or silty clay-clayey silt mixtures ML Inorganic silt; very fine sand; silty or clayey fine sand; clayey silt with low plasticity MH Inorganic silt; diatomaceous fine sandy or silty soils; elastic silt 5— • CL-ML Low plasticity clay to silt mixture ML-SM Sandy silt to silty sand mixture CL-SC Sandy clay to clayey sand mixture : SC-SM Clayey sand to silty sand mixture • 10— SW Well graded sand; gravelly sand, little or no fines SP Poorly graded sand; gravelly sand, little or no fines .1: SM Silty sand; poorly graded sand-silt mixture SC Clayey sand; poorly graded sand-clay mixture GW Well graded gravel; gravel-sand mixture, little or no fines GP Poorly graded gravel; gravel-sand mixture, little or no fines 15— sz GM Silty gravel; gravel-sand-silt mixture GC Clayey gravel; gravel-sand-clay mixture Sandstone Siltstone 20—a Claystone 0-049. Breccia (angular gravel and cobbles or matrix-supported conglomerate) Conglomerate (rounded gravel and cobble, clast-supported) Igneous granitic or granitic type rock Metavolcanic or metamorphic rock N 1.. I 25 III •-. II I Artificial or man-made fill Asphaltic concrete Portland Cement Concrete J 505A(11/77) LEIGHTON & ASSOCIATES GEOTECHNICAL BORING LOG B-i Date 1-7-97 Sheet 1 of 2 Project Carltas Company/Golf Cart Undercrossing, Hidden Valley Road Project No. 4930489-013 Drilling Co. Barges Drilling Service Type of Rig Hollow-Stemg Hole Diameter 8 in. Drive Weight 140 pounds Drop 30 in. Elevation Top of Hole +/- 188 ft. Ref. or Datum Mean Sea Level !- °-E M t GEOTECHNICAL DESCRIPTION Logged By SCB Sampled By SCB 0-7 SM fILL. -. . . @ 0'-2': Gray-brown, damp, medium dense, silty SAND; driller reports hard drilling at 3 feet SM TERRACE DEPOSITS/SANTIAGO FORMATION 185 - 0 : @ 2': Gray-brown, damp, very dense clayey SAND 180 SANTIAGO FORMATION @ 7': Gray-brown to pale-gray, damp, very dense, silty SAND with clay binder 10— 1 1 64/6 107.7 20.6 ML @ 10': Pale gray, damp, very stiff, fine sandy clayey SILTSTONE with black manganese-type staining 175 15- 170 - 0 20- - 2 65!3 124.3 10.6 @ 22': Pale gray to light brown, damp, very stiff, massive fine sandy to clayey 165 0 SII.TSTONE S Bag-3 13.8 @ 25': Pale gray, damp, very dense, slightly silty SANDSTONE SM 160 . 505A(11/77) LEIGHTON & ASSOCIATES GEOTECHNICAL BORING LOG B-i Date 1-7-97 Sheet 2 of 2 Project Caritas Company/Golf Cart Undercrossing, Hidden Valley Road Project No. 4930489-013 Drilling Co. Barges Drilling Service Type of Rig Hollow-Stem Auger Hole Diameter 8 in. Drive Weight 140 pounds Drop 30 in. P1vation Ton of Hole +1- 188 ft. Ref. or Datum Mean Sea Level L GEOTECHNICAL DESCRIPTION IL 0 . 110 IM 0 !' F . Z . .go ' Logged By SCB W ° o Sampled By SCB 30— 4 113.5 8.0 SM @ 30': Same as at 25 feet 155- 35—' 150 40 \@ 40': Same as at 25 feet Total Depth = 40 Feet - No Ground Water Encountered at Time of Drilling - Hole Backfilled with Soil Cuttings on January 7. 19917 145- 45' 140 50- 135 55- 130 505A(11/77) LEIGHTON & ASSOCIATES GEOTECHNICAL BORING LOG B-2 Date 1-8-97 Sheet 1 of 1 Project Carltas Company/Golf Cart Undercrossing, Cannon Road Project No. 4930489-013 Drilling Co. Barges Drilling Service Type of Rig Hollow-Stem Agç Hole Diameter 8 in. Drive Weight 140 pounds Drop 30 in. Elevation Top of Hole +1- 178 ft. Ref. or Datum Mean Sea Level GEOTECHNICAL DESCRIPTION h h. 12 Z ' : Logged By SCB W IL U Sampled By SCB SM TERRACE DEPOSITS - : @ 0'-15': Orangebrown, damp, medium dense to dense silty SAND 175 5. 170 - 10 1 50/4" 111.4 9.7 @ 10': Orange-brown, damp, very dense, medium to coarse grained silty SAND 165 @ 15': Pale gray, moist, dense silty clayey SAND 160 20— - 2 96/9" 98.4 4.6 SW/SP @ 22': Pale gray, damp, very dense, poorly graded coarse-grained SAND 155- 2.5— Bag-3 4.2 - 22'-2 - - :•.: - \@ 27': Practical refusal encountered on cobble/rock rial 0 - 150 - 0 . Total Depth = 27 Feet No Ground Water Encountered at Time of Drilling - Hole Backfilled on January 8, 1997 with Soil Cuttings 505A(11/77) .-. LEIGHTON & ASSOCIATES 1; 00•0., •j2 4930489-013 APPENDIX C Laboratory Testing Procedures and Test Results Expansion Index Tests: The expansion potential of selected materials was evaluated by the Expansion Index Test, U.B.C. Standard No. 18-2. Specimens are molded under a given compactive energy to approximately the optimum moisture content and approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared 1-inch thick by 4-inch diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap Water until volumetric equilibrium is reached. The results of these tests are presented in the table below: Compacted Dry Expansion Expansion Sample Location Sample Description Density (pci) Index Potential B @ 22' - 25' Fine sandy silt with clay 106.7 103 High B2 @ 22'-- 25' Well graded sand 116.0 0 Very Low .• ,• • •• •