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HomeMy WebLinkAboutCT 08-01; LA COSTA VIEWS; LIMITED SITE INVESTIGATION; 2001-06-09EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE "I" SANTEE, CALIFORNIA 92071 (619) 258-7901 Fax 258-7902 June 9, 2001 Legacy Development, LLC 6965 El Camino Real, Suite 105-451 Carlsbad, California 92009 Subject: Project No. 01-1147H1(1) Limited Site Investigation Proposed 26-Unit Apartment Complex 4 Vacant Lots, North Side of La Costa Avenue West of Romeria Street City of Carlsbad, California. Ladies! Gentlemen: In accordance with your request, we have performed a limited investigation of the soil conditions at the subject site. The investigation was undertaken to provide the soil engineering criteria for site grading and to recommend an appropriate foundation system for the proposed apartment complex. Our investigation found that the proposed building pads are primarily underlain by undocumented fill soils to a maximum depth of approximately 15 feet below existing grade. Mudstone and sandstone of the Santiago Formation were underlying the undocumented fill. The fill soils generally consist of soft to medium stiff sandy clay exhibiting a moderate expansion potential and a moderate compressibility. It is our opinion that the proposed development is, feasible provided the recommendations herein are implemented during construction. Respectfully submitted, P"a QLrIN, Mamadou Saliou Diaflo, P.E RCE 54071 LEGACY DE VELOPMEiW', LLC PROJECT NO. 01-1147111(1) INTRODUCTION This is to present the findings and conclusions of a soils investigation for a proposed 26-unit apartment complex to be located on the north side of La Costa Avenue, west of Romeria Street, in the City of Carlsbad, California. The objectives of the investigation were to determine the existing soils conditions and provide recommendations for site development. In order to accomplish these objectives, five (5) exploratory borings were drilled to a maximum depth of 31.0 feet; undisturbed and loose bag samples were obtained, and laboratory. tests were performed . SITE DESCRIPTION AND PROPOSED CONSTRUCTION The subject site is located on the north side of La Costa Avenue, west of Romeria Street, in the City of Carlsbad, California. The site was previously graded into 4 relatively level building pads. Priot to the grading operation, the site sloped moderately to the north. Vegetation consists of grass. The proposed development includes the construction of a 26-unit, two-story over garage apartment complex to be founded on caisson footings with a slab- on-grade floor system. FTLT INVESTIGATION Five exploratory borings were drilled with a gas-powered auger to a maximum depth of 31 feet on April 12, 2001 at the approximate locations shown on the attached Plate No. 1, entitled "Location of Exploratory Borings". A continuous log of the soils encountered was recorded at the time of excavation and is shown on Plates No. 2 & 6 entitled "Summary Sheet". The soils were visually and texturally classified according to the filed identification procedures set forth on the attached Plate No. 7 entitled "Uniform Soil Classification Chart. 2 LEGACYDEVELOPMENT, LLC PROJECT NO. 01-1147H1(1) SURFACE CONDITIONS The surface soils encountered during the c o u r s e o f o u r investigation were fill soils consisting of tan sand y c l a y , m o i s t to wet, loose to medium dense to a maximum depth o f f i f t e e n ( 1 5 ) feet. These soils were underlain by mudstone and sa n d s t o n e o f t h e Santiago Formation (Tsa). EXPANSIVE SOILS An expansion test was performed on representative sam p l e s o f t h e fill soils encountered to determine volumet r i c c h a n g e characteristics with change in moisture content. An E x p a n s i o n i n d e x of 61 indicates a moderate potential for expansion. GROUNDWATER Groundwater was not encountered during the cou r s e o f o u r investigation. Groundwater is anticipated at a depth g r e a t e r t h a n 100 feet., We do not expect ground water to affe c t t h e p r o p o s e d development. GEOLOGIC BAZABDS A review of the available geological literature pert a i n i n g t o t h e site indicates the existence of the Rose Canyo n F a u l t Z o n e approximately 10.5 Km to the west. Ground shaking fr o m t h i s f a u l t or one of the major active faults in the region is th e m o s t l i k e l y happening to affect the site. With respect to t h i s h a z a r d , t h e site is comparable to others in the general area. The proposed residential structures should b e d e s i g n e d i n accordance with seismic design requirements of t h e 1 9 9 7 U n i f o r m Building Code or the Structural Engineers A s s o c i a t i o n o f California using the following seismic design criteria: PARAMETER VALUE ' UBC REFERENCE Seismic Zone Factor, Z 0.40 Table 164 Soil Profile Type , SD Table 16-J Seismic Coefficient, Ca 0.44 Table 16-Q Seismic Coefficient, CV 0.64 Table 16-R Near-Source Factor, Na 1.0 . Table 16-S Near-Source Factor, Nv 1.0 Table 16-T Seismic Source B Table 16-1 3 LEGACY DE ViLOPMENT LLC PROJECTNO. 01-1147111(1) Based on the absence of shallow ground water, type and consistency of the underlying soils, it is our opinion that the potential for liquefaction is very low. CONCLUSIONS AND RECOMEIWATIONS The following conclusions and recommendations are based upon the analysis of the data and information obtained from our soil investigation. This includes visual inspection; field investigation; laboratory testing and our general knowledge of the soils native to the site. The site is suitable for the proposed development provided the recommendations set forth are implemented during construction. GRADING AND EARTHWORK Site grading should begin with clearing and grubbing, e.g. the removal of vegetation and deleterious materials. It is our understanding that the four previously graded pads will be graded into two level building pads. Therefore, we recommend that the existing fill soils to a minimum depth of five (5) feet be overexcavated, moisture conditioned 2 to 4 percent ovei\optimum and compacted to a minimum of 90 percent relative density. The compacted fill mat will provide support for the garage slabs, underground utilities, driveway and parking areas. Prior to the f il-i placement, the lower building pads should be overexcavated to a minimum depth of 2 feet, and recompacted as recommended above. The actual depth and extent of removal should be evaluated in the field at the time of excavation by a representative of this firm. Grading should be done in accordance with the attached appendix A. IMPORTED SOILS If imported soils are required to achieve proposed grades, they should be non-expansive, i.e. an expansion index of 20 or less and approved by the soils engineer prior to site delivery. LEGACY DEVELOPMENT, LLC PR OJECT NO. 01-1147H1(1) CAISSON FOUNDATION Due to the presence of undocumented fil l s o i l s t o a m a x i m u m d e p t h of 15 feet, a foundation system cons i s t i n g o f a c o m b i n a t i o n o f caissons and grade beams is recommended. The cast-in--drilled--hole (CIDH) concrete c a i s s o n s a r e a n t i c i p a t e d to be founded in the dense sandstone/ mu d s t o n e o f t h e S a n t i a g o Formation. The allowable static axial l o a d c a p a c i t i e s f o r C I D H concrete caissons may be obtained using t h e f o l l o w i n g T e r z a g h i a n d Peck equation: Quit= 9itCR2 + 27tCARZ Where: Quit = ultimate load capacity in compression C = cohesion in psf R = caisson radius CA = adhesion in psf A 12-inch diameter caisson founded t o a d e p t h o f 1 0 f e e t b e l o w existing grade may be designed for an al l o w a b l e l o a d c a p a c i t y o f 10 kips using a safety factor of 3. The design incorporates both side adh e s i o n a n d e n d b e a r i n g t o provide total pile capacity. It must • b e e m p h a s i z e d t h a t t h e "friction plus end bearing" condition c a n b e c o n s i d e r e d o n l y i f the bottom pile borings are cleaned of a l l l o o s e m a t e r i a l p r i o r t o the placement of steel reinforcement and c o n c r e t e . The load capacities of all caissons may b e i n c r e a s e d b y o n e - t h i r d for short-term transient loadings, s u c h a s w i n d a n d s e i s m i c activities. Resistance to uplift may be o b t a i n e d u s i n g a n a d h e s i o n between shaft and the concrete caisson of 7 5 0 p s f . N o a p p r e c i a b l e settlement is anticipated for caissons d e s i g n e d i n a c c o r d a n c e w i t h the recommendations and founded in the San t i a g o F o r m a t i o n . If caisson spacing is at least three t i m e s t h e c a i s s o n d i a m e t e r , no reduction in load capacity is consid e r e d n e c e s s a r y f o r a g r o u p effect. If structural design indicate s t h a t c a i s s o n s p a c i n g i s critical, the group action can be evalua t e d a f t e r t h e t o t a l c o l u m n load and geometric constraints are dete r m i n e d . It should be noted that the basic form u l a u s e d i s b a s e d o n l o a d transfer to the supporting sOil. Design con s i d e r a t i o n s a l s o s h o u l d be given to the caissons as structural mem b e r s . 5 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(J) The design of caissons to resist lateral loading at the grou n d level may be based on the curves shown on Plate No. 8. If greater deflection can be tolerated, lateral loads can be extrapolated to isolated caissons spaced no closer than 3 caisson diameters on center perpendicular to the line of thrust and 8 diameters on center parallel- to the line of thrust. The lateral resistance of caissons at ground level also depends significantly on the prope r implementation of site preparation. CONSTRUCTION CONSIDERATIONS The proper installation of CIDH caissons will be of critical importance. Since caisson design includes end bearing, it will be necessary to clean all loose material from the bottom of the borings. Caisson borings should be observed and approved by a representative of this firm prior to the placement of reinforcement 1LLO1ThBLE BEARING CAPACITY FOR GRADE BEAMS For the grade beams, an allowable soil bearing capacity of 1500 pounds per square foot may be used when founded a minimum of 12 inches into the compacted fill. This value may be increased by 2 0 percent for each additional foot of width and/or depth to a maximum value of 3000 lb/ft2. CONCRETE SLABS Concrete floor slabs should be a nominal 4 inches thick . Reinforcement should consist of #3 bars placed at 18 inches on center each way. Slab reinforcement should be placed within the middle third of the slab by supporting the steel on chairs or concrete blocks "dobies". The slab should be. underlain by 2 inch e s of clean sand over a 10-mil visqueen moisture barrier. The eff e c t of concrete shrinkage will result in cracks in virtually all concrete slabs. To reduce the extent of shrinkage, the concre t e should be placed at a maximum of 4-inch slump. The minimum ste e l recommended is not intended to prevent shrinkage cracks. LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(1) Where moisture sensitive floor coverings are anticipated over the slab, the 10-mil plastic moisture barrier should be underlain by a capillary break at least 4 inches thick, consisting of 3/4 inch crushed rock. SLOPE SETBACK Proposed structures and other improvements that are located within 8 feet of the face of existing slope could suffer differential movement as a result of the poor lateral stability of these soils. Therefore, caisson footings for the proposed residential development should be placed at least 8 feet back from the top of these slopes. ALTERNATIVE TO CAISSON FOUNDATIONS GRADING AND EARTHWORK Site grading should begin with clearing and grubbing, e.g. the removal of vegetation and deleterious materials. The undocumented fill and mudstone layer should be overexcavated, moisture conditioned 2 to 4 percent over optimum and compacted to a minimum of 90 percent relative density. The maximum depth of overexcavation is anticipated to be approximately 15. The actual depth and extent of removal should be evaluated in the field at the time of excavation by a representative of this firm. Grading should be done in accordance with the attached appendix A. FOUNDATION AND SLAB Continuous footings and/or spread footings are suitable for use and shall extend a minimum of 24 inches for the two story residential family dwellings into the compacted fill soils. Continuous footings should be 15 inches wide and reinforced with four #5 steel bars; two bars placed near the top of the footings and the other two bars placed near the bottom of the footings. Concrete floor slabs should be a minimum 4 inches thick. Reinforcement should consist of #3 bars placed at 12 inches on center each way. Slab reinforcement should be placed within the middle third of the slab by supporting the steel on chairs or concrete blocks "dobies". The slab should be underlain by 2 inches of clean sand over a 10-mil visqueen moisture barrier and another 2 inches of clean sand or gravel not exceeding 3/4 inch in size with no more than 5 percent passing the #200 sieve'. The effect of concrete shrinkage will result in cracks in virtually all concrete slabs. To reduce the extent of shrinkage, the concrete should be 7 LEGACY DEVELOPMENT, LLC PR OJECT NO. 01-1147H1(]) slabs. To reduce the extent of shrinkage, the concrete should be placed at a maximum of 4-inch slump. The minimum steel recommended is not intended to prevent shrinkage cracks. SOIL BEARING VALUE (COMPACTED FILL SOILS) An allowable soil bearing value of 1500 pounds per square foot may be used for the design of continuous foundations and spread footings founded a minimum of 12 inches into the compacted fill soils. This value may be increased by 300 psf for each additional foot of depth to a maximum value of 3000 lb/ft2. LATERAL SOIL PRESSURE Lateral resistance to horizontal movement may be provided by the soil passive pressure and the friction of concrete to soil. An allowable passive pressure of 150 pounds per square foot per foot of depth may be used. A coefficient of friction of 0.25 is recommended. The soils passive pressure as well as the bearing value may be increased by 1/3 for wind and seismic loading. SETTLEMENT Settlement of compacted fill soils is normal and should be anticipated. Based on the consolidation test results, a total settlement up to 0.75 inches across the structural span and a corresponding differential settlement up to 0.50 inches need to be considered in the structural design. UTILITY TRENCH EXCAVATIONS Excavations for on-site utility trenches may be made vertically for shallow depths and must be either shored or sloped at 1H: lv for depths greater than 4 feet. Utilities should. be bedded and backfilled with clean sand or approved granular soil to a depth of at least one foot over the pipe. This backfill shall be uniformly watered and compacted to a firm condition for pipe support. The remainder of the backfill shall be on-site soils or non-expansive imported soils, which shall be placed in thin lifts, moisture-conditioned and compacted to at least 90 % relative compaction. 8 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H](]) DRAINAGE Adequate measures shall be undertaken to properly finish grade the site, after the structures and other improvements are in place, such that the drainage water within the site and adjacent properties is directed away from the foundations, footings, floor slabs and the tops of slopes via surface swales and subsurface drains towards the natural drainage for this area. Proper surface and subsurface drainage will be required to minimize the potential of water seeking the level of the bearing soils under the foundations, footings and floor slabs, which may otherwise result in undermining and differential settlement of the structures and other improvements. LIMITS OF INVESTIGATION The recommendations provided in this report pertain only to the site investigated and based upon the assumption that the soil conditions do not deviate from those disclosed in the borings. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that planned at the present time, East County Soil Consultation and Engineering, Inc. should be notified so that supplemental recommendations can be provided. Plates No. 1 through 8, Pages L-1 through and L-4, References, Appendix A and Appendix C are parts of this report. Respectfully submitted, Mamadou Saliou Diallo RCE 54071 MSD/md - I' \\\- \\\ T' 7 - EAST COUNTY SOIL CONSULTATION & ENGINEERING, INC. 10925 HARThEY RD.. SUITE I, SANTEE, CA 92071 (619) 258-7901 Fax (619)258-7902 44w4 -z47y &2A2,4'ó5 '/-//47//'('1 NO. / LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(1) - 1 R BORING NO. 1 N M L P 0 A S L EQUIPMENT: GAS-POWERED AUGER T I C C I V D L L SAMPLING METHOD: E U E P S S C=CHIJNKSAMPLE D E C A B= BULK SAMPLE, ') F U= UNDISTURBED DRIVE 0 P I L I D N A N E C E T C A N E T F T T S N I E Y I I 1 0 E P 0 SOIL DESCRIPTION T N T E N Y % % o Sc FILL (Qal) - TAN BROWN, MOIST, LOOSE TO MEDIUM DENSE, CLAYEY SAND B - 100.1 21.5 88 2 3 - WET, MEDIUM DENSE 4 5 - 6 7 8 9 10 II SC SANTIAGO FORMATION (Tsa) - BLUEISH GRAY, MOIST TO WET, CLAYEY SAND 12 100.3 23.6 88 13 CL BROWN, MOIST, SOFT TO MEDIUM STIFF CLAY 13. 0'-I3. 5'= 8 BLOWS (SPT) * U - I3.5'-14.0'=I4 BLOWS (SPT) 14 I4.0'-14.5'=2S BLOWS (SPT) - I4.5-I5.0=I3 BLOWS (SPT) 15 15.0'-I5.5'=13 BLOWS (SPT) 105.7 19.6 - SM TAN, MOIST, DENSE, FINE GRAINED SILTY SAND 15. 5'-Ió. 0'=41 BLOWS (SPI) 16 - 103.7 19.3 17 BOTTOM OF BORING IS PLjtTENO.2 DATE LOGGED: APRIL 12,200! LOGGED BY: M. DUNCAN 10 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(1) I R BORING NO. 2. N M L I P 0 A S L EQUIPMENT: GAS-POWERED AUGER I C C T V D L L SAMPLING METHOD: E U E P S S C=CHUNKSAMPLE D E C A B= BULK SAMPLE, Y c P F U= UNDISTURBED DRIVE 0 P L i D N A N E C E T C A N E T F T T S N I E Y 1 1 T 0 P 0 SOIL DESCRIPTION T N T E N . Y % % 0 FILL(Qaf) TAN BROWN, MOIST TO WET, LOOSE TO MEDIUM DENSE, CLAYEY SAND 2 3 4 5 6 7 .8 9 10 12 13 SM SANTIAGO FORMATION (Tsa) - LIGHT TAN, MOIST, DENSE, FINE GRAINED SILTY SAND - -B 14 '5 - BOTTOM OF BORING 16 - 17 Is - PLATE NO. 3 DATE LOGGED: APRIL 12,2001 - LOGGED BY: M. DUNCAN 11 LEGACY DEVELOPMENT, LLC PROJECT NO. O1-1147fIJ(1) R BORING NO N M L P 0 A • EQUIPMENT: GAS-POWERED AUGER D L L SAMPLING METHOD: E U B P S S C=CHUNKSAMPLE D B C A B= BULK SAMPLE, y c U= UNDISTURBED DRIVE D N A N £ C E T C A N E T F T T S N I B Y I I T SOIL DESCRIPTION FILL (QaO o SC TAN BROWN, MOIST, LOOSE TO MEDIUM DENSE CLAYEY SAND 5 9. 0'-9. 5"8 BLOWS (SP7) - -U 10 9.5'40. 0'= 13 BLOWS (SF1) I0.0'-10.5'=4O BLOWS (SPT) 107.0 20,7 94 15 SANTIAGO FORMATION (Tsa) - CL DARK GRAYISH BROWN, MOIST, MEDIUM STIFF CLAY 20 SC- TAN MOIST, MOIST, DENSE CLAYEY SAND - SM 25 - SM TAN, MOIST, DENSE, FINE GRAINED SILTY SAND - BOTTOM OF BORING 30 AO DATE LOGGED: APRIL 12, 2001 LOGGED BY: M. DUNCAN 12 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-114 7 H 1 ( 1 ) I R BORING NO. 4 N M P 0 A S L EQUIPMENT: GAS-POWERED AUGER I C C T V D L L SAMPLING METHOD: E U E P S S C= CHUNK SAMPLE D E B= BULK SAMPLE, Y c U= UNDISTURBED DRIVE D N A N E C E T C A N E T F T T S N I E Y I - I T 0 P 0 . SOIL DESCRIPTION. T N T £ N y FILL (QA o SC TAN BROWN, MOIST, LOOSE TO MEDIUM DENSE; CLAYEY SAND -5 SANTIAGO FORMATION (Tsa) - CL DARK GRAYISH BROWN. MOIST, MEDIUM STIFF CLA Y 10 BROWN, MOIST, MEDIUM STIFF SANDY CLAY 15 20 SC- TAN MOIST, MOIST, DENSE; CLAYEY SAND - SM 25 - SM TAN MOIST, DENSE; FINE GRAINE SILTY SAND 30 8011DM OF BORING 35 PLATE NO.5 DATE LOGGED: APRIL I2;2001 LOGGED BY: M. DUNCAN 13 LEGACY DEVELOPMENT. LLC PR OJECT N O . 0 1 - 1 1 4 7 1 1 1 ( 1 ) I R BOIUNGNO. S N M L S L EQUIPMENT: GAS-POWERED AUGER T D L L SAMPLING METHOD: E U E P S S C= CHUNK SAMPLE D E C B= BULK SAMPLE, Y c U= UNDISTURBED DRiVE D N A N E C B T C A N E I F T T S N - I B Y I I T 0 E P 0 SOIL DESCRIPTION I N T E N V /o % O SC FILL (Qaf) - TAN BROWN, MOIST TO WET, LOOSE TO MEDIUM DENSE, CLAYEY SAND - 2 3 4 5 6 -7 8 9 10 LI 12 CL SANTIAGO FORMATION (Tsa) - BLUEISH GRAY, MOIST, SOFT TO MEDIUM STIFF CLAY 13 14 SM TAN MOIST, DENSE, FINE GRAINED SILTY SAND 15 16 17 170'-17.5'=28 BLOWS (SP'T) - I75'-I&O'=7O BLOWS (SFr) 18 0017GM OF BORING PLATE NO. 6 DATE LOGGED: APRIL 12,2001 LOGGED BY: M. DUNCAN 14 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1 1 4 7 H ] ( ] ) LABORATORY TEST RESULTS PAGE L-1. The maximum dry densities and optimum moisture co n t e n t s o f t h e f i l l m a t e r i a l s a s d e t e r m i n e d b y ASTM D1557-91, Procedure A and B which uses 25 blows of a 10 pound slide hammer falling from a height of 18 inches on each of 5 equal l a y e r s i n a 4 i n c h d i a m e t e r 1 / 3 0 c u b i c f o o t compaction cylinder and Procedure C which uses 56 blows of a 10 pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 6 inch diameter 1/13.3 cubic foo t compaction cylinder are presented as follows: OPTIMUM MAXIMUM MOISTURE DRY DENSITY CONTENT SOIL TYPE/PROCEDURE LB/CU. FT. % DRY WT. BORING NO. I® 1.0'TO 11.0' 1/A TAN BROWN SILTY CLAYEY 114.0 14.8 SAND An expansion test in conformance with UBC 18-2 was p e r f o r m e d o n r e p r e s e n t a t i v e s a m p l e s o f o n - site soils to determine volumetric change charac t e r i s t i c s w i t h c h a n g e i n m o i s t u r e c o n t e n t . T h e recorded expansion of the sample is presented as follo w s : INITIAL SATURATED INITIAL DRY MOISTURE MOISTURE DENSITY EXPANSION CONTENT% CONTENT% LB./CU. FT. INDEX BORING NO.2 @ 1.0' TO 3.5' 13.6 29.7 97.5 61 15 .5 10 30 35 40 KE 91 LATERAL RESISTANCE CAPACITY OF SINGLE CAISSONS ( X KIPS ) in i .4 - An ,- 1/4" caisson tor deflect on Legend.: . H 3H\ __— -\ \ \_ '. -___ — —• \4 H CAFSON \- )iAMç (4 36" — 30" . _:.2" _____ * _L.• •• . . ___ ___ ___ ___ \\ ___ Ar FIGURE 3 ALLOWABLE LATERAL RESISTANCE OF SINGLE DRILLED CAISSONS LEGACY DEVELOPMENT, LLC PROJECT NO. 01.-1147H1(1) REFERENCES 1: "1997 Edition, Uniform Building Code, Volume 2, Structur a l Engineering and Design Provisions". "Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada", Page 0-38, used with the 1997 Edition of the Uniform Building Code, Published by Internationa l Conference of Building Officials. "Geologic Maps of the Northwestern Part of San Diego County, California. Plate No. 2, Geologic Maps of the Encinitas and Rancho Santa Fe 7.5' Quadrangles", by Siang S. Tan and Michael P . Kennedy, 1996. "Soil Mechanics in Engineering Practice, 3rd Edition", by K. Terzaghi, R. B. Peck and G. Mesri, Dated 1996 "Drilled Piers and Caissons II", New York, NY, American Society of Civil Engineers, 153 p., Baker, C-M., Jr., Dated 1985. 16 CLASSIFICATION RANGE OF GRAIN SIZES U.S. STANDARD GRAIN SIZE IN SIEVE SIZE MILUMETERS BOULDERS Above 12 (aches Above 30 COBBLES l2 Inches To3 Inches 305 To 76.2 GRAVEL 3 Inches to No.4 762 to 4.16 Come 3 Inches to Inch 761 to 19.1 Fine 3 Inch to No. 4 19.Ito4.76 SAND No.4 to No. 200 476 to 0.074 Coarse No.4 to No. 10 4.76 to 2.00 Medium No. 10 to No. 40 2.00 to 0.420 Fine No. 40 to No. 200 0.420 to 0.074 SILT AND CLAY Below No. 200 Below 0.074 GRAIN SIZE CHART r12 EMMONS MENNIUM Mr - 0 10 zo 30 40 40 60 7 0 4 0 1 0 1 0 0 LiQUID LT CU.I. PLASTICITY CHART a. C ic MAJOR DIVISIONS SYMBOL DESCRIPTION OW WELL GRADED GRAVELS OR GRAVEL- SAND MIXTURES. LITTLE OR NO FINES OP POORLY GRADED GRAVELS OR GRAVEL-SAND MIXTURES. LITTLE OR NO FINES GRAVELS (MORE r ' OF COARSE FRACTION >140.4 SIEVE GM SILTY GRAVELS, GRAVEL-SAND-SILT MDcr U R E s COARSE SIZE) GRAINED SOILS cc CLAYEY GRAVELS, GRAVEL-SAND-CLAY MI X T U R E S (MORE THAN K OF SOIL> NO. 200 SIEVE SIZE) - SW WELL GRADED SANDS OR GRAVELLY SANDS, LITTLE OR NO FINES SANDS FRACTION <140.4 SIEVE (MORE THAN % OF COARSE SP POORLY GRADED SANDS OR GRAVELLY SANDS, LITTLE OR 140 FINES SM SILTY SANDS, SILT-SAND MIXTURES SIZE) Sc CLAYEY SANDS, SAND-CLAY MIXTURES SILTS & ML INORGANIC SiLTS AND VERY FINE SANDS, R O C K FLOUR. SILTY OR CLAYEY FINE SANDS OR CLAYEY szus WITH SLIGHT PLASTICITY FINE GRAINED SOILS (MORE THAN Yz OF SOIL < NO. 200 SIEVE SIZE) CLAYS LIQUID LIMIT <50 CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY. GRAVELLY CLAYS, SANDY CLAYS, - SILTY CLAYS. LEAN CLAYS OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY SILTS & ME INORGANIC SILTS, MICACEOUS OR DIA T O M A C E O U S FINE SANDY OR SILTY 500.3, EIsnc siurs CE INORGANIC CLAYS OF HIGH PLASTICITY. FAT CLAYS CLAYS LIQUID LIMIT >50 OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTY CLAYS, ORGANIC SILTS HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS CLASSIFICATION CHART (UNWIEDSOIL CLASSIFICATION SYS T E M ) EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. LEGACY DEVELOPMENT LLC PROJEC T 10925RARTLEY ROAD, SUITE "r PROJECT NO. 01-1147111(1) SANTEE, CALIFORNIA 92071 JUNE 8., 2001 U.S.C.S. SOIL CLASSIFICATION PLATE NO. 7 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(J) LABORATORY TEST RESULTS PAGE L-1 The maximum dry densities and optimum moisture contents of the fill materials as determined by ASTM D1557-91, Procedure A and B which uses 25 blows of a 10 pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 4 inch diameter 1/30 cubic foot compaction cylinder and Procedure C which uses 56 blows of a 10 pound slide hammer falling from a height of 18 inches on each of 5 equal layers in a 6 inch diameter 1/13.3 cubic foot compaction cylinder are presented as follows: MAXIMUM MOISTURE DRY DENSITY CONTENT SOIL TYPE/PROCEDURE LB/CU. FT. % DRY WT. BORING NO.1 @ 1.0'TO 11.0' 1/A TAN BROWN SILTY CLAYEY 114.0 14.8 SAND An expansion test in conformance with IJBC 18-2 was performed on representative samples of on- site soils to determine volumetric change characteristics with change in moisture content. The recorded expansion of the sample is presented as follows: INITIAL SATURATED INIllAL DRY MOISTURE MOISTURE DENSITY EXPANSION CONTENT% CONTENT% LBJCU. FT. iNDEX BORING NO. 2 @ 1.0' TO 3.5' 13.6 29.7 97.5 61 15 DIRECT SHEAR SUMMARY 5000 .4500 4000 3500 -t U- U)3000 U) U) Ui. 2500 U) lu 2000 1500 1000 500 0-. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 NORMAL STRESS [PS9 (2 13132" SAMPLE) j 2M (0.545) IL (1.093) 2L (2.185) ANGLE OF COHESION INTERNAL INTERCEPT SAMPLE DESCRIPTION FRICTION (PSF) H5 © 17 Undisturbed 300 300 SOUTHERN CALIFORNIA LEGACY DEVELOPMENT, LLC PROJECT (7 SOIL & TESTING, INC. BY: DBAISD DATE: 04-27-01 IJOB NUMBER01-1147R1(1) - PAGE L-1 I I . _ DIRECT SHEAR SUMMARY 5000 4500 4000 3500 AN 3000 2500 U) tu 2000 1500 1000 500 i I I It 'H 1:. 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 NORMAL STRESS [PS9 (2 13/32" SAMPLE) 2M (0.545) IL (1.093) 2L (2.185) ANGLE OF COHESION INTERNAL INTERCEPT SAMPLE DESCRIPTION FRICTION (PSF) H3 © 9'-10 Undisturbed 22 0 1000. SOUTHERN CALIFORNIA LEGACY DEVELOPMENT, LLC PROJECT - SOIL & TESTING, INC. Y: DBAJSD DATE: 04-27-01 IJOBNUMBER-- 01-1147}11(fl PAGE L-2 4 __•uiii •aaaii ImElml •_ aiiii_________ I .Il•I •uaiii INEEllowmall - _mii____ •siiiu I •iuii— I Nulill -_IIIl 1 •RIIII RIII I _.IIII •uii I •RIIII aaauii _.IIII_________ I •iii _.IIII auaiii •uuiii -auiii •uaiii __________ aiui_________ Rallil RURRI. I _IIII IiIi •iii_________ - RIUfl •uiii 11 0.5 1.0 5.0 10.0 LOAD (kip I sq. ft..) H3 @ 10'-15' SOUTHERN CALIFORNIA LEGACY DEVELOPMENT, LLC PROJECT SJ SOIL & TESTING, INC. BY: DBNKMS IDATE: 04/27101 - IJOBNUMBER--01-1147u1(1 PAGE L-4 LEGACY DEVELOPMENT, LLC PROJECT NO. 01-1147H1(1) REFERENCES 1: "1997 Edition, Uniform Building Code, Volume 2, Structural Engineering and Design Provisions". "Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada", Page 0-38, used with the 1997 Edition of the Uniform Building Code, Published by International Conference of Building Officials. "Geologic Maps of the Northwestern Part of San Diego County, California. Plate No. 2, Geologic Maps of the Encinitas and Rancho Santa Fe 7.5' Quadrangles", by Siang S. Tan and Michael P. Kennedy, 1996. - "Soil Mechanics in Engineering Practice, 3rd Edition", by K. Terzaghi, R. B. Peck and G. Mesri, Dated 1996 "Drilled Piers and Caissons II", New York, NY, American Society of Civil Engineers, 153 p., Baker, C.M., Jr., Dated 1985. 16 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE I SANTEE, CALIFORNIA 92071 (619) 258-7901 APPENDIX A RECOMMENDED EARTHWORK SPECIFICATIONS 1. General Description The intent of these specifications is to obtain uniformity and adequate strength in filled ground so that the proposed structures may be safely supported. The procedures include the clearing and preparation of the land to be filled, processing the fill soils, the spreading, and compaction of the filled areas to conform with the lines and grades as shown on the approved plans. The owner shall retain a Civil Engineer qualified in soil mechanics (herein referred to as engineer) to inspect and test earthwork in accordance with these specifications. The 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. Preparing Areas to be Filled All brush, vegetation and any biodegradable refuse shall be removed or otherwise disposed of so as to leave the areas to be filled free of vegetation and debris. Any uncompacted filled ground or loose compressible natural ground shall be removed unless the report recommends otherwise. Any buried tanks or other structures shall be removed and the depression backfllled to the satisfaction of the engineer. The natural ground which is determined to be satisfactory for the support of the filled ground shall then be plowed or scarified to a depth of at least 12 inches (12"). After the natural ground has been prepared, it shall then be brought to the proper moisture content and compacted to. not less than 90 percent of maximum dry density in accordance with ASTM D1557-91. Where fills are made on slopes greater Than 20 percent, horizontal benches shall be cut into the firm natural ground. The initial bench at the toe of the fill shall be at least 15 feet in width on firm undisturbed natural ground. The width of all succeeding benches shall be at least 6 feet. APPENDIX A 2 3. Fill Materials All material shall be approved by the engineer and shall consist of materials free from vegetable matter, and other lumps greater than 6 inches in diameter. If, during grading operations, soils are found which were not encountered and tested in the preliminary investigation, tests on these soils shall be performed to determine their physical characteristics. Any special treatment recommended. in the preliminary or subsequent soils reports not covered herein shall become an addendum to these specifications. 4. Placing and Compacting Fill Materials When the moisture content of the till material is below that specified, water shall be added until the moisture content is near optimum to assure uniform mixing and effective compaction. When the moisture content of the fill materials is above that specified, the fill material shall be aerated by blading and scarifying or other satisfactory methods until the moisture content is near optimum as specified. After processing, the suitable fill materials shall be placed in layers which, when compacted, shall not exceed six inches (6"). Each layer shall be spread evenly and shall be thoroughly mixed during the spreading insure uniformity of materials and moisture in each layer. After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to not less than the density set forth in paragraph 2 (c) above. Compaction shall be accomplished with approval types of compaction equipment Rolling shall be accomplished while the fill material is at the specified moisture content. In place density tests shall be performed in accordance with ASTM D1556-90. The surfaces of the fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compacting operations shall be continued until the slopes are stable and until there is no appreciable amount of loose soil on the slopes. 5. Inspection Sufficient inspection by our firm or the Soil's Engineer of record and/or his/her representative shall be maintained during the filling and compacting operations so that he/she can verify that the fill was constructed in accordance 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 interrupted by rain, fill operations shall not be resumed until the moisture content and density of fill are as previously specified. All recommendations presented in the attached report are a part of these specifications. 2 EAST COUNTY SOIL CONSULTATION AND ENGINEERING, INC. 10925 HARTLEY ROAD, SUITE I SANTEE, CALIFORNIA 97.071 (619) 258-7901 RECOMMENDED PROCEDURES FOR SLA B F O U N D A T I O N S BASED ON EXPANSION INDEX For soils that are expansive with respect to change in volume with change in moisture content, there is no economical way to absolutely prevent movement if there is a change in moisture content. Therefore, insofar as it is feasible, stable soil moisture content should be established and maintained throughout the life of the structures. Since it is usually not practical to maintain a completely stable soil moisture content, in order to minimize the undesirable effects of the expansive soils on the structures if these soils are placed or allowed to remain within the upper three feet below finish grade, it is recommended that the following special precautions be exercised in design and construction of slabs and foundations. Design of foundations and slabs on expansive soils are presented in Table 1 based on expansion indices and there may be more stringent structural design or agency requirements. As an alternative to conventionally reinforced concrete foundations, post-tensioned structural slab systems, designed by a structural engineer, may be utilized. Footing depth should be measured below lowest exterior finish grade. A reinforced concrete grade beam should be constructed across garage entrances, with similar depth and reinforcement as adjacent perimeter footings for all soils with expansion potential greater than "very low". For soil with a potential expansion greater than "low", interior isolated spread footings are not recommended. Where pre-saturation is recommended beneath interior slabs, the recommended moisture should penetrate to one foot below the depth of the perimeter footings. Pre-saturation should be completed at least 24 hours prior to concrete placement. 1. For soils with an expansive index greater than "low" slab reinfo r c e m e n t s h o u l d b e s t r u c t u r a l l y tied to the footings. APPENDIX C g. In buildings where it is feasible to permit independent movement of sl a b s w i t h r e s p e c t t o foundations, such as in garages and warehouses, these slabs should be separated from the foundations by 1/2-inch thickness of construction felt or equivalent Special care should be exercised to assure that the separation extends to the full depth of the thickened edges of slab and that no appurtenances are attached to the building and also the slabs. Ii. Provide a moisture barrier, such as 1 0-mil visqueen overlain by 2 inches of sand below slabs in areas that receive flooring which might be adversely affected by capillary moisture. Where a base course is recommended beneath interior slabs, it should consist of pea gravel, clean sand, or other acceptable granular material, i.e. a capillary break at least 4 inches thick, consisting of sand, gravel or 3/4 inch crushed rock with no more than 5 percent passing the No. 200 sieve. The above moisture barrier/sand cover requirement may be included as part of the recommended base course thickness. Slab reinforcement should be supported at mid-slab height on chairs or concrete blocks. Provide positive drainage away from all perimeter footings to a horizontal distance of at least five feet outside the building walls. APPENDIX C FOOTINGS SLABS___________ EXPANSION DEPTH BELOW GRADE INDEX REINFORCEMENT THICKNESS REINFORCEMENT PRESATIJRATION BASE UBC 18-2 1-STORY 2-STORY COURSE 12 INCH 18 INCH 2 #5 STEEL BARS #3 BARS® 18" OPTIMUM VERY LOW PERIMETER PERIMETER I TOP 4 INCHES ON CENTER MOISTURE (0-20) 1 BOTTOM NOMINAL EACH WAY LOW 12 INCH 18 INCH (21-50) INTERIOR INTERIOR 4 #5 BARS MEDIUM 24 INCH 24 INCH 2 TOP #3 BARS ® 12" 2 TO 4 PERCENT 4 (51-90) PERIMETER PERIMETER 2 BOTTOM 4 INCHES ON CENTER ABOVE INCHES OR NET EACH WAY OPTIMUM IS INCH 19 INCH 2#6BARS INTERIOR INTERIOR I TOP I BOTTOM 4 #5 BARS HIGH 30 INCH 30 INCH 2 TOP #4 BARS® 16 3105 PERCENT 6 (91-130) PERIMETER PERIMETER 2 BOTTOM 5 INCHES INCHES ON ABOVE INCHES OR NET CENTER EACH OPTIMUM 18 INCH 18 INCH - 2 #8 BARS WAY INTERIOR INTERIOR 1 TOP I BOTTOM 36 INCH 36 INCH 4 #6 BARS #4 BARS® 12 4106 PERCENT 6 VERY HIGH PERIMETER PERIMETER 2 TOP 6 INCHES INCHES ON ABOVE INCHES (>131) 2 BOTTOM NET CENTER EACH OPTIMUM 30 INCH 30 INCH WAY INTERIOR INTERIOR