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HomeMy WebLinkAbout; Worthing - Jones Residences; Solis Report; 1984-10-01GEOTECHNICAL INVESTIGATION YORTHING-JONES RESIDENCES 1644 TAHARACK AVENUE CARLSBAD, CALIFORNIA PREPARED FOR 6. T. W. 690 Elm Avenue, Suite 204 Carlsbad, California 92008 PREPARED BY Southern California Soil & Testing, Inc. Post Office Box 20627 6280 Riverdale Street San Diego, California 92120 October 1, 1984 G. T. W SCS&T 25170 690 Elm Avenue Report No. 1 Suite 204 Carlsbad, California 92008 Attention: Brooks Worthing SUBJECT: Report of Geotechnical Investigation, Worthing-Jones Residences, 1644 Tamarack Avenue, Carlsbad, California. Gentlemen: In accordance with your request, we have completed a geotechnical investi- gation for the proposed project. We are presenting herewith our findings and reconunendations. The findings of this study indicate that the site is suitable for the proposed development provided the special site preparation and foundation recommendations presented in the attached report are complied with. If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC. a?+< ,I-,&+ Curtis R. Burdett, C.E.G. #lo90 RRR:CRB:mw cc: (6) Submitted (1) SCS&T, Escondido SOUTHERN CALIFORNIA SOIL AND TESTINCi, I N 0. TABLE OF CONTENTS PAGE Introduction and Project Description ..................................... 1 Project Scope ............................................................ 1 Findings ................................................................. 2 Site Oescription ..................................................... 2 General Geology and Subsurface Conditions ............................ 3 Geologic Setting and Soil Description ........................... 3 Tectonic Setting ................................................ 3 Geologic Hazards ..................................................... 4 Groundwater ..................................................... 4 Recommendations and Conclusions .......................................... 5 Site Preparation ..................................................... 5 Deleterious Materials ........................................... 5 Corrective Grading .............................................. 5 Surface Drainage ................................................ 5 Earthwork ....................................................... 5 Foundations .......................................................... 6 General ......................................................... 6 Lateral Resistance .............................................. 6 Settlement Characteristics ...................................... 6 Expansive Characteristics ....................................... 6 Limitations .............................................................. 6 Review, Observation and Testing ...................................... 6 Uniformity of Conditions ............................................. 7 Change in Scope ...................................................... 7 Time Limitations ..................................................... 8 Professional Standard ................................................ 8 Client's Responsibility .............................................. 8 Field Explorations ....................................................... 9 Laboratory Testing ....................................................... 9 ATTACHMENTS Plate 1 Plot Plan Plate 2 Unified Soil Classification Chart Plate 3-4 Trench Logs Plate 5 Direct Shear Test Results Maximum Dry Density and Optimum Moisture APPENDIX Recommended Grading Specification and Special Provisions GEOTECHNICAL INVESTIGATION WORTHING-JONES RESIDENCES 1644 TAMARACK AVENUE CARLSBAD, CALIFORNIA INTRODUCTION AN0 PROJECT DESCRIPTION This report presents the results of our geotechnical investigation for two proposed residences which are to be located at and adjacent to 1644 Tama- rack Avenue in the City of Carlsbad, State of California. A brief legal description of the site is Parcel 2 and 3 of P.M. 12830 in the City of Carlsbad. It is our understanding that two, one or two-story, wood-framed structures with slab-on-grade construction are planned for this site. It is our understanding that some grading will be necessary to develop the site and that the maximum cuts and fills planned are in the order of 5 feet or less. This information was taken from the grading plan prepared by Brian Smith Engineers. The site configuration and exploration loca- tions are shown on Plate Number 1. PROJECT SCOPE This investigation consisted of: surface reconnaissance; subsurface explorations; obtaining representative disturbed and undisturbed samples; laboratory testing; analysis of the field and laboratory data; research of SOUTHERN CALIFORNIA SO!L AND TESTINE. INC. SCS&T 25170 October 1, 1984 Page 2 available geological literature pertaining to the site; and preparation of this report. Specifically, the intent of this analysis was to: a) b) cl d) e) f) Explore the subsurface conditions to the depths influenced by the proposed construction. Evaluate, by laboratory tests, the pertinent engineering prop- erties of the various strata which will influence the develop- ment, including their bearing capacities, expansive characteris- tics and settlement potential. Define the general geology at the site including possible geo- logic hazards which could have an effect on the site development. Develop soil engineering criteria for site grading. Determine potential construction difficulties and provide recom- mendations concerning these problems. Recommend an appropriate foundation system for the type of struc- tures anticipated and develop soil engineering design criteria for the recommended foundation design. FINDINGS SITE DESCRIPTION The project site is a nearly rectangular shaped lot, approximately 100 feet wide by 210 to 220 feet deep, that is located adjacent to and north of Tamarack Avenue in the City of Carlsbad. The site is bounded on the east and west by developed residential lots and on the north by vacant land. The lot slopes gently to the south with elevations ranging from SOUTHERN CALIFORNIA SOIL AND TEEjTINCi. INC. SCS&T 25170 October 1, 1984 Page 3 approximately 175 feet to 183 feet. An existing lo-foot wide drainage easement is present along the eastern property line. Vegetation consists of a moderate growth of grasses, shrubs, and trees. No structures cur- rently occupy the site but a substantial amount of end-dumped fill is present in the central portion of the site. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County and is underlain by Quaternary-age alluvial deposits and artificial fill. Specific soils conditions as encountered in our exploratory trenches consisted of brown to reddish brown and dark brown, medium dense, porous, silty sands. End- dumped fill soils also consisting of brown to reddish brown, silty sands are present in the central portion of the site. TECTONIC SETTING: A review of available geologic maps indicates the subject site to be located approximately 5 miles east of the Rose Canyon Fault Zone. The Rose Canyon Fault Zone is a series of northwest trending faults of Quaternary age that is currently classified as potentially active, rather than active according to the criteria of the California Division of Mines and Geology. This classification is based on the lack of conclusive evidence to verify Holocene movement along this fault zone. No fault traces have been mapped through, or ismediately adjacent to, the subject site and a surface reconnaissance yielded no evidence of faulting at the site. It should be recognized that much of Southern California is characterized by major, active fault zones that could possibly affect the subject site. The nearest of these are the,Elsinore Fault Zone, located approximately 25 miles to the northeast, and the Coronado Banks Fault zone, located approxi- mately 20 miles to the southwest. SOUTHERN CALIFORNIA SOIL AND T E 5 T , N G. I N c. SCS&T 25170 October 1, 1984 Page 4 GEOLOGIC HAZARDS The subject site can be considered to be relatively free of geologic hazards. Potential hazards such as tusnamis, seiches, liquefaction, or landsliding should be considered to be negligible or nonexistent. The most likely major geologic hazard to affect the site is groundshaking as a result of movement along one of the major active fault zones men- tioned previously. The maximum bedrock accelerations that would be attri- buted to a maximum probable earthquake occurring along the nearest portion of selected fault zones that could affect the site are sumnarized in the following table. TABLE I Maximum Probable Maximum Bedrock Fault Zone Classification Distance Earthquake Acceleration Rose Canyon Potentially 5.0 miles 6.0 magnitude 0.38 g Active Elsinore Active 25 miles 7.3 magnitude 0.20 g Coronado Banks Active 20 miles 6.0 magnitude 0.12 g Based on the current fault zone classification and the maximum bedrock accelerations capable of developing, it is recommended that the Elsinore Fault Zone be considered the design earthquake source for the subject development. Construction in accordance with the minimum standards of the Uniform Building Code and the governing agency should minimize potential damage due to seismic activity. GROUNDRATER: No groundwater was encountered during our subsurface explora- tion and we do not anticipate any major groundwater related problems, either during or after construction. SOUTHERN CALIFORNIA SOlI. AND TE57,NG. INC. SCS&T 25170 October 1, 1984 Page 5 RECOMMENDATIONS AND CONCLUSIONS SITE PREPARATION DELETERIOUS MATERIALS: All deleterious materials generated from the clearing and grubbing operations should be legally disposed of off-site. CORRECTIVE GRADING: We recommend that the existing fill soils and loose native soils be removed to firm natural ground and be stockpiled for future use. Firm natural ground is defined as native soil which possesses an in-situ density equal to or greater than 85% of its maximum dry den- sity. The soils exposed at the base of these excavations should then be scarified 12 inches, be moisture treated to at least 2% over optimum and densified to a minimum of 90% relative compaction. The stockpiled soils may then be replaced in eight inch lifts, moisture treated and compacted as indicated above. Based on the findings of this study, it appears that the maximum depth of removal and recompaction will be on the order of 2 to 3 feet. SURFACE DRAINAGE: We recommend that all surface drainage should be direc- ted away from the proposed structures and that ponding of water not be allowed adjacent to their foundations. EARTHWORK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Recomnended Grading Specifications and Special Provisions. All special site preparation recomnendations presented in the sections above will supersede those in the standard Recommended Grading Specifications. All embankments, struct- ural fill, and fill should be compacted to a minimum of 90%. Utility trench backfill within 5 feet of the proposed structures and beneath asphalt pavements should be compacted to a minimum of 90% of its maximum dry density. The maximum dry density of each soil type should be deter- mined in accordance with A.S.T.M. Test Method 1557-78, Method A or C. SOUTHERN CALIFORNIA SCIIL AND TESTING. INC. SCS&T 25170 October 1, 1984 Page 6 FOUNDATIONS GEWERAL: It is our opinion that the proposed structure may be supported by spread footings. All footings should be founded at least 12 inches ' below lowest adjacent finished grade with a minimum width of 12 inches. An allowable soil bearing pressure of 1800 pounds per square foot may be used for foundation design. We further reconmend that all continuous footings be reinforced with at least one No. 4 bar top and bottom. LATERAL RESISTANCE: Resistance to lateral loads may be provided by fric- tion at the base of the footing and by passive pressure against the adja- cent soil. For concrete footings on compacted soil, a coefficient of friction of 0.38 may be used. For calculating passive pressure, an equiva- lent fluid unit weight of 250 pounds per cubic foot may be used. Passive pressure should not exceed 1,500 pounds per square foot. When combining frictional and passive resistance, the latter should be reduced by one- third. SETTLEMENT CWARACTERISTICS: The anticipated total and/or differential settlements for the proposed structure may be considered to be within tolerable limits provided the recommendations presented in this report are followed. EXPANSIVE CHARACTERISTICS: The prevailing foundation soils were found to be nondetrimentally expansive and will not require special consideration and/or design. LIMITATIONS REVIEW, OBSERVATION AND TESTING The recomnendations presented in this report are contingent upon our review of final plans and specifications. The soil engineer and engineer- SOUTHERN CALIFORNIA 501L AND TESTING. INC SCS&T 25170 October I, 1984 Page 7 ing geologist should review and verify the compliance of the final grading plan with this report and with Chapter 70 of the Uniform Building Code. It is recornnended that Southern California Soil and Testing, Inc. be retained to provide continuous soil egineering services during the earth- work operations. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from that anticipated prior to start of construction. UNIFWIITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsur- face soil conditions encountered at the subsurface exploration locations and the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undis- closed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the soils engineer so that he may make modifi- cations if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that it may be determined if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. SOUTHERN CALIFORNIA 50,L AND T E 5 T, N 0. I N c. SCS&T 25170 October 1, 1984 Page 8 TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the State-of-the-Art and/or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession cur- rently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encoun- tered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations are based solely on the information obtained by US. We will be responsible for those data, interpretations, and recommendations, but shall not be respon- sible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY It is the responsibility of 6. T. W., or their representative to ensure that the information and recommendations contained herein are brought to SOUTHERN CALIFORNIA SOIL AND TESTINCi. INC SCS&T 25170 October 1, 1984 Page 9 the attention of the engineer and architect for the project and incorpo- rated into the project's plans and specifications. It is further their responsibility to take the necessary measures to ensure that the contrac- tor and his subcontractors carry out such recommendations during construc- tion. FIELD EXPLORATIONS Two subsurface explorations were made at the locations indicated on the attached Plate Number 1 on September 14, 1984. These explorations con- sisted of trenches dug by means of a backhoe. The field work was con- ducted under the observation of our engineering geology personnel. The explorations were carefully logged when made. These logs are presen- ted on the following Plate Numbers 3 and 4. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart on Plate Number 2. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are presented. The density of granular material is given as either very loose, loose, medium dense, dense or very dense. Disturbed and "undisturbed" samples of typical and representative soils were obtained and returned to the laboratory for testing. LABORATORY TESTING Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (A.S.T.M.) test methods or suggested procedures. A brief description of the tests performed is presented below: SOUTHERN CALIFORNIA 501L AND TESTING. INC SCS&T 25170 October 1, 1984 Page 10 a) b) cl d) MOISTlJRE-DENSITY: Field moisture content and dry density were determined for representative undisturbed samples 'obtained. This information was an aid to classification and permitted recogni- tion of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the field moisture content is determined as a percentage of the soil's dry weight. The results are sununarized in the trench logs. CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System. DIRECT SHEAR TESTS: Direct shear tests were performed to deter- mine the failure envelope based on yield shear strength. The shear box was designed to accomodate a sample having a diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and at saturated moisture content. The shear stress was applied at a constant rate of strain of approximately 0.05 inches per minute. The results of these tests are presented on attached Plate Number 5. CDHPACTION TEST: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with A.S.T.M. Standard Test O-1557-70, Method A. The results of these tests are presented on the attached Plate Number 5. SDUTHERN CALIFORNIA SOIL AND T E 5 T I N G. I N c. ,:. h .i? 6 5 .T’.L” ‘p co1.z cues,~, ---- - 4 c-&L: SCALE i%40’ LEGEND: m TRENCH LOCATION SOUTHERN CALIFORNIA SOIL & TESTING,INC. sv: SHS DATE: g-26-84 JOB NUMBER: 25170 Plate No. 1 SUBSURFACE EXPLORATION LEGEND .*. UNIFIED SOIL cLASS*FIcATION Cx4RT .son. DESCRIPT*ON GROUP SynaO‘ TYPIC~ NAXES 1. COARSE GRAIYED, “ore elIan half Of material is &gqg than No. 200 sieve *it*. m CLEAN GIUVELS GH we11 graded gravels, gravel- More than half OL sand mixtures, little or no coarse fnction is fines. larger than Ha. 4 GP Poorly graded gravels, gravel *ieve size but sand mixtures, little or no *ma11rr than 3". - fines. GP.AvET.S WITH FINES GN ;si1ey qrave1r. pOor1y gr&a ,*ppreci?L& amoY@.t gravel-sand-silt mixtures. of fines) .GC Clayey gravr1a. paxly graded gravel-**rd. clay mixture,, . CLEAN SA.NDS SW we11 graded ran&ave11y nor* than half or *and*, little oFno fill**. co*rs* fraction is SP Poorly graded .an~.,gra"elly smaller than NO. 4 **"ds, little or "0 co**. sieve *ink. SANDS WITH FINES SM si1ey rands, paor1y gr*ded mDereci*blc amount *ana *Iv3 silt mixture*. . . of fines) SC Clayey sands, poorly graded sand and clay mixtures. 11. -PME G?.AINm, “ore than half of material 11 *mailer than NO. 200 ricvc .ile. SILTS ANO CLAYS .: Liquid Limit less than 50 STLT.5 Am MYS ML. Inormmic silts *nd V*N tina~sands, rock rl."r,-.andv *ilC or clayey-silt-sand nixeurer with slight plaat- i&b Inor&tnic clays of lud to medium plasticity,gravelly clays, sandy cla**,silty clay.. lean e1ayr. Organic stlta and organic silty clays of 1s~ plasticity IInorgnnic silts. micacaous or diaenoaceous tine *andy or silty roils, elastic Liquid'Limit .*ilts. pi Inorganic clays of high greater than* 50 , pkat1city. tat e1aya. -.a-! Organic clay* of medium to high plas+city. HJGi(LY ORGANIC SOILS IT Peat *n* other highly organic roils. f ‘:. __. - Water level at rime of.ex:avation or as indicated us - lJndisturbecl,,dri;en ring samole 6r tube sample CK =_ .,., Undisturb<d cl&~< sample ' BS - Bulk sample SOUTHERN CALIFORNIA SOIL & TESTING, INC. mm-0 q ,“LmDAL= STRIZET IAN D1.00, CIILlEOEINlA rnP,DO BY OATE g-26-84 JOB NO. 25170 Plate No. 2 : ii 2 c TRENCH NUMBER 1 I- w c;* z &Iii 2 7 = Jo’ EC tzc YI~V) iii = ,ws =z cct;z z- :* s: ‘I: c iI ELEVATION i “,” kfi “5. 2;;: “0; -P z; ; :: “,=a 6; LGa iz :, z “,” 2 =z 0 0 DESCRIPTION : SM Reddish Brown, Silty Dry Loose Sand (Fill) 1 CK SM - BG Brown To Reddish Brown, Humid Medium 114.5 4.5 z- Silty Sand Dense (Native) 3- CK 101.1 3.1 4- 5- 5- 7- _ CK 3- 3- 1r lr- SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG SOIL & TESTlNG,lNC. LOGGED BY: CRB DATE LOGGED:9-14-B4 JOB NUMBER: z E E ; TRENCH NUMBER 2 k” kc> E ii ; : zzb w- = ,z :z Luyu) Ej : ;; cc+2 z- Y 5; 0 G. ELEVATION “,” 5; <I?u E i ;t zw mii 2”O -0 :,” 6: ig i 2 z +? o 2 O * EO =0 ci 0 DESCRIPTION 0 SM Reddish Brown, Silty Dry Loose To Medium 1- Sand Dense _ CK z- BG 3- CK 4 - CK SM Dark Brown, Silty Sand Humid Medium 96.4 5.5 5- BG -Dense 6- CK 96.2 5.7 7- CK B- 9- UJ- li- SOUTHERN CALIFORNIA SUBSURFACE EXPLORATION LOG SOIL & TESTING,INC. LOGGED BY: DATE LOGGED: g-14-84 RR JOB NUMBER: pj170 Plate No. 4 DIRECT SHEAR TEST RESULTS DESCRIPTION MAXIMUM DENSITY and OPTIMUM MOISTURE CONTENT ASTM 1557 - 78 A METHODS DESCRIPTION SOUTHERN CALIFORNIA BOIL 6 TESTINGI, INC. . ..O II”.“PAL. .T”..T ..N m.00. CALICOmNIA ..,.)O BY RRR DATE 10-2-84 JOB NO. 25170 Plate No. 5 . m stonaora s/eves Uydromet er 2. I. Y$ % YO e?a wl llBLl fMlnu/L?Sl Groin Sfze fmnd PARTICLE SIZE LIMITS I I eCuLDER~COEeLES GRAVEL I SAND SILT OR CLAY , GJar*a Fine cmrra Medium Fill* (12 in.) I 3 in. 3/4 la No.4 NalO NO43 No. 200 u. s. ST4NDARD .SICVE SIZE SAMPLE T-l (h l-2 SCS&T 25170 October 1, 1984 Appendix, Page 1 WORTHING-JONES RESIDENCES, 1644 TAMRACK AVENUE, CARLSBAD RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS GENERAL INTENT The intent of these specifications is to establish procedures for clear- ing, compacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary soil investiga- tion report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the soil report for which they are a part. No deviation from these specifications will be allowed, except where specified in the soil report or in other written communication signed by the Soil Engineer. OBSERVATION AND TESTING Southern California Soil & Testing, Inc. shall be retained as the Soil Engineer to observe and test the earthwork in accordance with these speci- fications. It will be necessary that the Soil Engineer or his representa- tive provide adequate observation so that he may provide an opinion that the work was or was not accomplished as specified. It shall be the re- sponsibility of the contractor to assist the soil engineer and to keep him apprised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary soil report are encountered during the grading operations, the Soil Engineer shall be contacted for further recommendations. SCS&T 25170 October 1, 1984 Appendix, Page 2 8 If, in the opinion of the Soil Engineer, substandard conditions are en- countered, such as; questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., he will be empower- ed to either stop construction until the conditions are remedied or cor- rected or recommend rejection of this work. Test methods used to determine the degree of compaction should be per- formed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content - A.S.T.M. D-1557-78. Density of Soil In-Place - A.S.T.M. D-1556-64 or A.S.T.M. D-2922. All densities shall be expressed in terms of Relative Compaction as deter- mined by the foregoing A.S.T.M. testing procedures. PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished apperance, free from unsightly debris. Any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above des- cribed procedures should be backfilled with acceptable soil that is com- pacted to the requirements of the Soil Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, SDUTNERN CALIFORNI* 501L AND TESTING. I N c. SCS&T 25170 October 1, 1984 Appendix, Page 3 storm drains and water lines. Any buried structures or utilities not to be abandoned should be investigated by the Soil Engineer to determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth in the Geotechnical Report. The top of the cap should be at least 4 ~feet below finish grade or 3 feet below the bottom of footing whichever is'greater. The type of cap will depend on the.diameter of the well and should be determined by the Soil Engineer and/or a qualified Structural Engineer, When the slope of the natural ground receiving fill exceeds 20% (5 hori- zontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent soil condition. The lower bench shall be at least 10 feet wide or 1 l/2 times the equipment width which ever is greater and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified hereinbefore for compacted natural ground. Ground slopes flatter than 20% shall be benched when considered necessary by the Soil Engineer. After clearing or benching, the natural ground in areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture con- tent, compacted and tested for the minimum degree of compaction in the Special Provisions or the recommendation contained in the preliminary soil investigation report. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in--situ density of at least 85% of its maximum dry density. SOUTHERN CALIFORNIA SOIL AND TESTINO. I N c. SCS&T 25170 October 1, 1984 Appendix, Page'4 FILL MATERIAL Materials placed in the fill shall be approved by the soil engineer and shall be free of vegetable matter and other deleterious substances. Gran- ular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks, expansive and/or detrimen- tal soils are covered in the soils report or Special Provisions. Expan- sive soils, soils of poor gradation, or soils with low strength character- istics may be thoroughly mixed with other soils to provide satisfactory fill material, but only 'with the explicit consent of the soil engineer. Any import material shall be approved by the Soil Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compac- tion effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the minimum speci- fied degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary soil investigation report. When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is SOUTHERN C*LIFORNI* 501l. AND TESTINO. 1 N 0. SCS&T 25170 October 1, 1984 Appendix, Page 5 achieved. The maximum size and spacing of rock permitted in structural fills and in non-structural fills is discussed in the soil report, when applicable. Field observation and compaction tests to estimate the degree of compac- tion of the fill will be taken by the Soil Engineer or his representative. The location and frequency of the tests shall be at the Soil Engineer's discretion. When the compaction test indicates that a particular layer is less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Soil Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot rollers shall be at vertical intervals of not greater than four feet. In addition, fill slopes at ratios of two horizontal to one vertical or flatter, should be track- rolled. Steeper fill slopes shall be over-built and cut-back to finish contours. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90% of maximum dry density or that speci- fied in the Special Provisions section of this specification. The compac- tion operation on the slopes shall be continued until the Soil Engineer is satisfied that the slopes will be stable in regards to surficial stabil- ity. Slope tests will be made by the Soils Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Soil Engineer in the form of a daily field report. SOUTHERN CAL,FORNIA SO!L AND TESTING. I N c. SCS&T 25170 October 1, 1984 Appendix, Page 6 If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no additional cost to the Owner or Soils Engineer. CUT SLOPES The Engineering Geologist shall inspect all cut slopes excavated in rock or lithified formational material during the grading operations at inter- vals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Soil Engi- neer to determine if mitigating measures are necessary. Unless otherwise specified in the soil and geological report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Soil Engineer or his representative shall be made during the filling and compacting operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. The presence of the Soil Engineer or his representative or the observation-and testing shall not release the Grading Contractor from his duty to compact all fill material to the specified degree of compac- tion. S”I,TUEC)N C.LIFDRNIA 50,L AND TESTING. INC SCS&T 25170 October 1, 1984 Appendix, Page 7 SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS-SPECIAL PROVISIONS The minimum degree of compaction to be obtained in compacting natural ground, in the compacted fill, and in the compacted backfill shall be at least 90 percent. Detrimentally expansive soil is defined as soil which will swell more than 3 percent against a pressure of 150 pounds per square foot from a condi- tion of 90 percent of maximum dry density and air dried moisture content to saturation. Oversized fill material is defined as rocks or lumps over 6 inches in diameter. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. Transition Lots: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfill. SOUTHERN CALIFORNIA SOIL AND T E 5 T 0 N 0. I N c.