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Home My WebLink AboutMS 01-02; CALAVERA HILLS VILLAGE R; INTERIM REPORT OF GEOTECHNICAL INVESTIGATION; 1990-04-12INTERIM REPORT OF 1(ICAL fllVESTIGATICN CAIAVERA HEIQflS VULPA R fit EARTHWORK DEPT. PREPARED FOR: Lyon Camimities, Incorporated 4330 La Jolla Village Drive, Suite 130 San Diego, California 92122 PREPARED BY: Southern Cal i fornia Soil & Iting, Inc. Post Office Box 20627 6280 Riverdale Street San Diego, California 92120 ,4'?f 91-0a... SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 6280 RIVERDALE ST. SAN DIEGO. CALIF. 92120 • TELE 2804321 • P.D. Box 20627 SAN DIEGO, CALIF. 92120 678 ENTCRPRISE ST. ESCONOIDO, CALIF. 92025 • TELE 746•4544 April 12, 1990 Lyon Cotmiunites, Incorporated 4330 La Jolla Village Drive Suite 130 SCS&T 9021023 San Diego, California 92122 Report No. 1 TTENrION: Mr. George Haviar SUBJECT: Interim Geotechnical Investigation, Calavera Heights, Village R, Carlsbad, California. Gentlenen: In accordance with your request, we have conpieted an interim geotechnical investigation for the subject project. We are presenting herewith our findings and recc,zmndations. In general, we found the site suitable for the proposed developtent provided the reconnendations presented in the attached report are followed. If you have any questions after reviewing the contents contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respect ly tted, INC.SWnr7IA 67 a t, Daniel B. Mier, R. .E. #36037 #1237 DBA: JRH:nw cc: (2) submitted (4) Hunsaker and Associates (1) SCS&T, Escondido SOUTHERN CALIFORNIA SOIL AND TESTING. INC. Introduction and Project Description .1 Project Scope .............................................................. 2 Findings...................................................................3 SiteDescription.......................................................3 General Geology and Subsurface Conditions..............................3 Geologic Setting and Soil Description.............................3 Tectonic Setting.................................................. GeologicHazards..................................................5 Slope Stability...................................................5 Groundshaking.....................................................5 Groundwater.......................................................6 Conclusions and Recaniendations ............................................ 6 General................................................................6 Grading...........................................................7 Site Preparation..................................................7 SelectGrading....................................................7 Cut/Fill Transition ................................................ 8 InçortedFill.....................................................8 SlopeConstruction.................................................8 SurfaceDrainage ....... . ....................... . .................. 8 Earthwork......................... .... ............ .. .............. 8 SlopeStability.... ................................... . .... . ........... 9 Foundations..... . ... . ....... . ................... . ...................... 9 General............... .. .... . ..................................... 9 Reinforcent............................... ... ............... ...10 InteriorConcrete Slabs-on-Grade ................. . ............... 10 Exterior Concrete Slabs-on-Grade. .... . ........................... 11 Special Lots ....... . ........... ... ............................... 11 Expansive Characteristics ................. . ................ . ..... 11 Settlement Characteristics .............. . ................. . ...... 11 EarthRetaining Walls.. ..... . ............. . ........................... 12 Passive Pressure ...... . .......... . ............................... 12 Active Pressure ....................................... . .......... 12 Ba.cicfill ............................. . ........................... 12 TABLE OF CCW11'S (continued) PAGE Factor of Safety .12 Limitations...............................................................13 Review, Observation and Testing.......................................13 Uniformity of Conditions .............................................. 13 Change in Scope.......................................................13 Tine Limitations.......................................................14 Professional Standard.................................................14 Client's Responsibility ............................................... 14 FieldExplorations........................................................15 LaboratoryTesting .......................................................... 15 TREU Table I The Maxini.un Bedrock Accelerations, Page 5 FIGURE Figure 1 Site Vicinity Map, Follows Page 1 PLAM Plates 1 Plot Plan Plate 2 Unified Soil Classification Chart Plate 3 Plates 4-7 Trench Logs Plates 8-9 Grain Size Distribution Plate 10 Conpaction Test Results Plate 11 Expansion Test Results Plate 12 Direct Shear Suninary Plate 13 Slope Stability Calculations Plate 14 Weakened Plane Joint Detail Plate 15 Retaining Wall Subdrain Detail APPENDIX Recuninanded Grading Specification and Special Provisions 5E~ SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 6280 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 280.4321 • P.O. BOX 20627 SAN DIEGO, CALIF. 92120 670 EPITCRPRISC ST. ESCONOIOO. CALIF. 92025 • T E L E 746•4544 CAI.AVERA HEIGHTS VILLAGE R CARLSBAD, CALIFORNIA This report presents the results of our interim report of geotechnical investigation for Calavera Heights Subdivision, Village R, to be located at the southeastern intersection of Tamarack Avenue and Knollod Drive (both proposed), in the City of Carlsbad, California. The site location is illustrated on the following Figure Number 1. It is our understanding that the site will be developed to receive a residential subdivision with associated paved streets. It is anticipated that the structures will be one and/or two stories high and of wood frane construction. Shallow foundations and conventional slab-on-grade floor systems are proposed. Grading will consist of cuts and fills up to approximately six feet and 30 feet deep, respectively. Cut and fill slopes up to approximately 30 feet and ten feet high, respectively, are also anticipated. All slopes will be constructed at a 2:1 (horizontal to vertical) inclination. Th assist with the preparation of this report, we were provided with an undated tentative plan prepared by Hunsaker and Associates dated January 30, 1990. In addition, we reviewed our "Report of Supplemental Investigation SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 'ARLS BAD I I I t"•'7 - V - I ! , POUTE 78 — -- °'-' *_ ----. - _LJ - •' -- — - •7•• ' • '- , . - •- , 0 - -ç '4 •-.,_/• -:4 0c 11SNA0 't A - — -. /'.. SOUTHIRN CALIFORNIA CALAVERAS HEIGHTS SOIL a TUTINQ,INCU CRBIWDW 'DATE: 4-13-90 JOB NUMBER: 9021023 FIGURE #1 SCS&T 9021023 April 12, 1990 Page 2 Calavera Hills Villages Q and T," dated October 6, 1988 (Reference Number 1) and our "Report of Preliminary Geotechnical Investigation, Calavera Hills Subdivision," dated August 6, 1984 (Reference Number 2). The site configuration, topography and approximate locations of the subsurface explorations are shown on Plates Number 1, 1A and lB of this report. This interim report is based on review of the aforementioned supplemental report for Villages Q and T and the preliminary report for the Calavera Hills Subdivision. A site specific report will be prepared at a later date when further field investigation and analysis of laboratory data has been completed. For the purpose of this report, appropriate field investigation and laboratory test data was extrapolated from the previous report. ttre specifically, the intent of this interim study was to: Describe the subsurface conditions to the. depths influenced by the proposed construction. The laboratory testing performed in the referenced reports was used to evaluate the pertinent engineering properties, including bearing capacities, expansive characteristics and settlement potential, of similar materials which will influence the development of the proposed subject site. Further laboratory testing will be performed on actual on-site materials, once additional field investigation is performed. C) Define the general geology at the site including possible geologic hazards which could have an effect on the site development. d) Develop soil engineering criteria for site grading and provide recoirnendations regarding the stability of proposed cut and fill slopes. SCS&T 9021023 April 12, 1990 Page 3 Address potential construction difficulties and provide recomtndations concerning these problems. Reconitend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the reconitended foundation design. The subject site, designated as Village R in the Calavera Heights development, is an irregular shaped portion of land located at the southeastern intersection of Tamarack Avenue and Knollod Drive (both proposed) in the City of Carlsbad, California. The vacant site covers approximately 5.12 acres and is bounded by undeveloped land. Topographically, the site is comprised of hilly terrain which generally slopes towards the south, southwest and southeast. Elevation differentials range to approximately 70 feet from the northwestern portion to the southern portion of the site. Drainage is acconplished via sheetf low and a well developed drainage swale on the westerly portion of the site. Vegetation is comprised of a noderate to heavy growth of chaparral, shrubs, small trees and grasses. No structures were noted on the site, however a 150-foot-wide SDG&E easement with electrical transmitter towers traverses the site approximately at the middle. Minor amounts of over sized concrete and household debris have been dumped on site. A lake is located south of the site. ILxIC SETTM SOIL DESCRIPrIa: The subject site is located near the boundary between the Foothills Physiographic Province and the Coastal Plains Physiographic Province of San Diego County and is underlain by siltstones and sandstones of the Eocene Santiago Formation, Tertiary Paleosol and surf icial residuum. SCS&T 9021023 April 12, 1990 Page 4 The site is underlain by si1tstons and sandstones of the Santiago Formation deposits. The Santiago Formation at the site appears to be characterized largely by greyish white sandstones with minor siltstones. It should be noted that the Santiago Formation is highly lenticular and substantially different conditions may be encountered at similar elevations within relatively short distances. Some of these conditions may include weak siltstones or claystones sonetines associated with slope stability problems. The topsoils/subsoil horizon associated with the Santiago Formation is conprised of approximately two feet of brown, silty sand topsoil over to to three feet of brown, sandy clay subsoil. A zone of ancient paleosol is present in scattered areas of the project site. This paleosol is the result of the torrid climate and relatively stable geologic conditions that were present in the San Diego area during the early Cenozoic era. The resulting ancient soil (paleosol) is lateritic and consists predominantly of low expansive sandy clays and silty sands. A thin residual cap of ironstone concretions and siliceous pebbles is present on imich of the paleosol. ¶IiuJIC brrr1r: A few small, apparently inactive faults have been mapped previously within the vicinity of the site. No evidence of faulting was noted in our exploratory trenches for the referenced reports but it is possible that future grading operations at the site may reveal some of these faults. Due to their status of activity and geometry, these small faults should be only of minor consequence to the project. It should also be noted that several prominent fractures and joints which are probably related, at least in part, to the strong tectonic forces that dominate the Southern California region are present within the vicinity of the site. These features are usually near-vertical and strike in both a general northwesterly direction (subparaflel to the regional structural trend) and in a general northeasterly direction (subperpendicular to the regional structural trend). All cut slopes should be inspected during grading by a qualified geologist to assess the presence of adverse jointing and bedding conditions in the final slopes. SCS&T 9021023 April 12, 1990 Page 5 In addition, 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 is the Elsinore Fault Zone, located approximately 20 miles to the northeast. It should also be noted that the possible off-shore extension of the Rose Canyon Fault Zone is located approximately eight miles west of the site. The Rose Canyon Fault Zone comprises a series of northwest trending faults that could possibly be classified as active based on recent geologic studies. Recent seismic events along a small portion of the Rose Canyon Fault Zone have generated earthquakes of 4.7 or less magnitude. Other active fault zones in the region that could possibly affect the site include the Coronado Banks and San Clemente Fault Zones to the west, the Agua Blanca and San Miguel Fault Zones to the south, and the Elsinore and San Jacinto Fault Zones to the northeast. (QWGIC IThZA1)S: The site is located in an area which is relatively free of potential geologic hazards. Hazards such as tsunamis, seiches, liquefaction, and landsliding should be considered negligible or nonexistent. SLOPE STABILITY: The siltstone and claystone portions of the Santiago Formation typically have relatively weak shear strengths which may result in potential slope instabilities. The site should be observed for potential geologic hazards during grading by a qualified geologist. JNDSHAK1M: One of the most likely geologic hazards to affect the site is groundshaking as a result of novenent along one of the major, active fault zones mentioned above. The maximum bedrock accelerations that would be attributed to a maximum probable earthquake occurring along the nearest portion of selected fault zones that could affect the site are suninarized in the following Table I. Maximum Probable Bedrock Design Fault Zone Distance Earthquake Acceleration acceleration Rose Canyon 8 miles 6.5 magnitude 0.36 g 0.23 g Elsinore 20 miles 7.3 magnitude 0.25 g 0.17 g Coronado Banks 24 miles 7.0 magnitude 0.18 g 0.12 g San Jacinto 43 miles 7.8 magnitude 0.14 g 0.10 g SCS&T 9021023 April 12, 1990 Page 6 Earthquakes on the Rose Canyon Fault Zone are expected to be relatively minor. Major seismic events are likely to be the result of movement along the Coronado Banks, San Jacinto, or Elsinore Fault Zones. Experience has shown that structures that are constructed in accordance with the Uniform Building Code are fairly resistant to seismic related hazards. It is, therefore, our opinion that structural damage is unlikely if such buildings are designed and constructed in accordance with the minimum standards of the most recent edition of the Uniform Building Code. GROUNDWATER: No groundwater was encountered during our subsurface explorations for the referenced reports. Even though no major groundwater problems are anticipated either during or after construction of the proposed development, seasonal groundwater from precipitation runoff may be encountered within the larger drainage swale during grading for the development. It should be realized that groundwater problems may occur after development of a site even where none were present before development. These are usually minor phenomena and are often the result of an alteration of the permeability characteristics of the soil, an alteration in drainage patterns and an increase in irrigation water. Based on the permeability characteristics of the soil and the anticipated usage of the development, it is our opinion that any seepage problems which may occur will be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when they develop. In general, no geotechnical conditions were encountered which would preclude the development of the site as tentatively planned provided the recommendations presented herein are followed. SCS&T 9021023 April 12, 1990 Page 7 The main geotechnical consideration for site development is the anticipated presence of expansive subsoils underlying the site. These deposits typically extend to a thickness of approximately three feet. This condition will require select grading as described herein. The purpose of this interim report is to provide preliminary recoimendations based on information available from the referenced reports. An additional investigation based on the present development scheme will be performed at a later date. SITE 1 RaTI(1: Site preparation should begin with the removal of any existing vegetation and deleterious matter from proposed improvement areas. Removal of trees should include their root system. Any existing loose surficial deposits in areas to receive settlement-sensitive improvements should be removed to firm ground. It is estimated that the extent of topsoil will be approximately two feet. Firm natural ground is defined as soil having an in-place density of at least 90 percent. Soils exposed in the excavations should be scarified to a depth of 12 inches, moisture conditioned and recompacted to at least 90 percent as determined in accordance with ASTM D 1557-78, Method A or C. The minimum horizontal limits of removal should include at least five feet beyond the perimeter of the structures, and all areas to receive fill and/or settlement-sensitive nç,rovenenis. SELEL"r (DflL: Expansive soils should not be allowed within four feet from finish pad grade. In addition, expansive soils should not be placed within a distance from the face of fill slopes equal to ten feet or half the slope height, whichever is more. Select material should consist of granular soil with an expansion index of less than 50. It is recommended that select soils have relatively low permeability characteristics. In areas undercut for select grading purposes, the bottom of the excavation should be sloped at a minimum of three percent away from the center of the structure. Minimum lateral extent of select grading should be five feet away from the perimeter of settlement-sensitive inprovients. SCS&T 9021023 April 12, 1990 Page 8 CtJ1'/FUL flNITICV: It is anticipated that a transition line between cut and fill soils may run through some of the proposed building pads. Due to the different settlement characteristics of cut and fill soils, construction of a structure partially on cut and partially on fill is not recommended. Based on this, we recommend that the cut portion of the building pads be undercut to a depth of at least three feet below finish grade, and the materials so excavated replaced as uniformly compacted fill. The mininim horizontal limits of these recommendations should extend at least five feet outside of the proposed improvements. IMIV}fl'ED FILL: All fill soil imported to the site should be granular and should have an expansion index, of less that 50. Further, import fill should be free of rock and lumps of soil larger than six inches in diameter and should be at least 40 percent finer than 1/4-inch. Any soil to be imported should be approved by a representative of this office prior to importing. SWPE aGTL'rICxJ: The face of all fill slopes should be compacted by backrolling with a sheepsfoot compactor at vertical intervals no greater than four feet and should be track walked when completed. Select grading should be performed to limit expansive soils within ten feet from face of fill slope or one half the slope height, whichever is greater. Recommendations contained within this report reflect a select grading condition. All cut slopes should be observed by our engineering geologist to verify stable geologic conditions. Should any unstable conditions be found, mitigating measures could be required. SUI AD: It is recommended that all surface drainage be directed away from the structures and the top of slopes. Ponding of water should not be allowed adjacent to the foundations. EARilK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Reconrended Grading Specifications and Special Provisions. All special site preparation recomendations presented in the sections above will supersede those in the SCS&T 9021023 April 12, 1990 Page 9 Standard Recoitu.nded Grading Specificatirns. All embankments, structural fill and fill should be compacted to at least 90% relative compaction at or slightly over optimum moisture content. Utility trench backfill within five feet of the proposed structures and beneath asphalt pavements should be compacted to minimum of 90% of its maximum dry density. The upper twelve inches of subgrade beneath paved areas should be compacted to 95% of its maximum dry density. This compaction should be obtained by the paving contractor just prior to placing the aggregate base material and should not be part of the mass grading requirements. The maximum dry density of each soil type should be determined in accordance with ASTh Method D 1557-78, Method A or C. Proposed cut and fill slopes should be constructed at a 2:1 (horizontal to vertical) or flatter inclination. It is estimated that cut and fill slopes will extend to a maximum height of about ten feet and 30 feet, respectively. It is our opinion that said slopes will possess an adequate factor of safety with respect to deep seated rotational failure and surf icial failure (see Plate Number 13). The engineering geologist should observe all cut slopes during grading to ascertain that no adverse conditions are encountered. It should be noted that the Santiago Formation is highly Lenticular and substantially different conditions may be encountered at similar elevations within relatively short distances. Some of these conditions may include weak siltstones or claystones sometimes associated with slope stability problem. GENERAL: If the lots are capped with nondetrinentally expansive soils, conventional shallow foundations may be utilized for the support of the proposed structures. The footings should have a minimum depth of 12 inches and 18 inches below lost adjacent finish pad grade for one-and-two-story construction, respectively. A minimum width of 12 inches and 18 inches is reconinended for continuous and isolated footings, respectively. A bearing SCS&T 9021023 April 12, 1990 Page 10 capacity of 2000 psf may be assumed for said footings. This bearing capacity may be increased by one-third when considering wind and/or seismic forces. Footings located adjacent to or within slopes should be extended to a depth such that a minimum distance of six feet and seven feet exist between the footing and the face of cut slopes or fill slopes, respectively. Retaining walls in similar conditions should be individually reviewed by this office. If it is found to be unfeasible to cap the lots with nondetrittentally expansive soils as recoimended, special foundation and slab design will be necessary. This generally consists of deepened and more heavily reinforced footings and thicker and xtore heavily reinforced slabs. Reconmendations for expansive soil conditions will be provided after site grading when the expansion index and depth of the prevailing foundation soil is known. REINFO1IMENT: Both exterior and interior continuous footings should be reinforced with at least one No. 4 bar positioned near the bottom of the footing and one No. 4 bar positioned near the top of the footing. This reinforcement is based on soil characteristics and is not intended to be in lieu of reinforcent necessary to satisfy structural considerations. If expansive soils exist within four feet of finish grade, additional reinforcing will be necessary. INTERIOR CONCRETE ON-GRADE SLABS: If the pads are capped with nondetrinentally expansive soils, concrete on-grade slabs should have a thickness of four inches and be reinforced with at least No. 3 reinforcing bars placed at 36 inches on center each way. Slab reinforcement should be placed near the middle of the slab. As an alternative, the slab reinforcing may consist of 6"x6"-W1.4xW1.4 (6"x6"-10/10) welded wire mesh. Hover, it should be realized that it is difficult to maintain the proper position of wire mesh during placement of the concrete. A four-inch-thick layer of clean, coarse sand or crushed rock should be placed under the slab. This layer should consist of material having 100 percent passing the half-inch screen; no ncre than ten percent passing sieve #100 and no nore than five percent passing sieve #200. Where moisture-sensitive floor coverings are SCS&T 9021023 April 12, 1990 Page 11 planned, the sand or rock should be overlain by a visqueen moisture barrier and a two-inch-thick layer of sand or silty sand should be provided above the visqueen to allow proper concrete curing. EMMOR StBS-i-GW: For nonexpansive soil conditions, exterior slabs should have a minim= thickness of four inches. Walks or slabs five feet in width should be reinforced with 6 "x6 "-Wi. 4xW1 .4 (6"x6"-10/10) welded wire mesh and provided with weakened plane joints. Any slabs between five and ten feet should be provided with longitudinal weakened plane joints at the center lines. Slabs exceeding ten feet in width should be provided with a weakened plane joint located three feet inside the exterior perimeter as indicated on attached Plate Number 14. Both traverse and longitudinal weakened plane joints should be constructed as detailed in Plate Number 14. Exterior slabs adjacent to doors and garage openings should be connected to the footings by dowels consisting of No. 3 reinforcing bars placed at 24-inch intervals extending 18 inches into the footing and the slab. SPECIAL LOTS: Special lots are defined as lots underlain by fill with differential thickness in excess of ten feet. The following increased foundation recuuutndations should be utilized for said lots. Footings should be reinforced with two No. 4 bars positioned near the bottom of the footing and two No. 4 bars positioned near the top of the footing. Concrete on grade slabs should be reinforced with at least No. 3 reinforcing bars placed at 18 inches on center each way. Lots with fill differentials in excess of thirty feet should be evaluated on an individual basis. EXPANSIVE CHAR&"1ISTICS: The reconrendat ions contained in this report reflect a nondetrinentally expansive soil condition resulting from a select grading operation. SETflEM212 amRIsrI(: The anticipated total and/or differential settlements for the proposed structures way be considered to be within tolerable limits provided the reconnendations presented in this report are followed. It should be recognized that minor hairline cracks on concrete due to shrinkage of construction materials or redistribution of stresses are normal and my be anticipated. SCS&T 9021023 April 12, 1990 Page 12 PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be considered to be 450 pounds per square foot per foot of depth up to a maximum of 2000 psf. This pressure may be increased one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.35 for the resistance to lateral iitwenent. When combining frictional and passive resistance, the former should be reduced by one-third. The upper 12 inches of exterior retaining wall footings should not be included in passive pressure calculations when landscaping abuts the bottom of the wall. ACTIVE PRESSURE: The active soil pressure for the design of unrestrained earth retaining structures with level backf ills may be assumed to be equivalent to the pressure of a fluid weighing 35 pounds per cubic foot. For 2:1 (horizontal to vertical) sloping backf ills, 14 pcf should be added, to the preceding values. These pressures do not consider any surcharge. If any are anticipated, this office should be contacted for the necessary increase in soil pressure. This value assumes a drained backfill condition. Waterproofing details should be provided by the project architect. A subdrain detail is provided on the attached Plate Number 15. BFUL: All backfill soils should be compacted to at least 90% relative compaction. Expansive or clayey soils should not be used for backfill material. The wall should not be backfilled until the masonry has reached an adequate strength. FIOR OF SAFF.'r!: The above values, with the exception of the allowable soil bearing pressure, do not include a factor of safety. Appropriate factors of safety should be incorporated into the design to prevent the walls from overturning and sliding. SCS&T 9021023 April 12, 1990 Page 13 ,u VW I (1:1 The reconitendations presented in this report are contingent upon our review of final plans and specifications. Such plans and specifications should be made available to the geotechnical engineer and engineering geologist so that they may review and verify their compliance with this report and with Chapter 70 of the Uniform Building Code. It is reconuended that Southern California Soil & Testing, Inc. be retained to provide continuous soil engineering services during the earthwork operations. This is to verify compliance with the design concepts, specifications or reconuendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. LIIiIi.L.j&SI kN 1 1)in1ui The reconnendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and on 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 undisclosed or unforeseen variations in the soil conditions that may occur in the internediate 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 geotechnical engineer so that he may make modifications if necessary. :61, i Ies This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. SCS&T 9021023 April 12, 1990 Page 14 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 Standards-of-Practice 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 recoimEndations. In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encountered at the locations where our trenches, surveys, and explorations are made, and that our data, interpretations, and recoindations are based solely on the information obtained by us. We will be responsible for those data, interpretations, and reconiiendations, but shall not be responsible 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. It is the responsibility of Lyon Communities, Incorporated, or their representatives to ensure that the information and reconundations contained herein are brought to the attention of the structural engineer and architect SCS&T 9021023 April 12, 1990 Page 15 for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out such recormendations during construction. One subsurface trench exploration was made at the locations indicated on the attached Plate Number 1 on December 21, 1982 within the subject site (see Plate Number 3). In addition, Plates Number 4 through 7 extracted from the referenced report (Reference Number 2) contain additional trench excavations on similar soils within the Calavera Heights Subdivision. These explorations consisted of trenches dug by the means of a backhoe. The field work was conducted under the observation of our engineering geology personnel. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart on Plate 2. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are provided. The density of granular soils is given as either very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTh) test methods or suggested procedures. A brief description of the tests performed is presented below: a) aASSIFICATIC: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System. SCS&T 9021023 April 12, 1990 Page 16 b) !.DISIURE-DENSITY: In-place noisture contents and dry densities were determined for representative soil samples. This information was an aid to classification and permitted recognition of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the in-place moisture content is determined as a percentage of the soil's dry weight. The results are summarized in the trench logs. C) QADI SIZE DISflU7YICZ4: The grain size distribution was determined for representative samples of the native soils in accordance with ASTM D422. The results of these tests are presented on Plates Number 8 and 9. rI()1 TEST: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with ASTN Standard Test D-1557-78, Method A. The results of these tests are presented on the attached Plate Number 10. EXPIC1 rrsr: The expansive potential of clayey soils was determined in accordance with the following test procedure and the results of these tests appear on Plate Number 10. Allow the trimmed, undisturbed or renolded sample to air dry to a constant moisture content, at a temperature of 100 degrees F. Place the dried sample in the consolidoneter and allow to compress under a load of 150 psf. Allow noisture to contact the sample and measure its expansion from an air dried to saturated condition. DJ.Kp1'r SHEAR TESTS: Direct shear tests were performed to determine the failure envelope based on yield shear strength. The shear box was designed to accommodate a • sample having a SCS&T 9021023 April 12, 1990 Page 17 diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and a saturated moisture content. The shear stress was applied at a constant rate of strain of approximately 0.05 inches per minute. The average shear strength values for granitic and metavolcarLic rock are presented on attached Plate Number 12. CapT 8 9-40 PUD 892O HDP 89-54 1 GENERAL NOTES: : APN # 168-040-22 TOTAL AREA 5.I2 ACRES DEVELOPED AREA 2.9 ACRES TOTAL OPEN SPACE APPROXIMATELY ACRES NATURAL OPEN SPACE ACRES EXISTING LAUD USE 0S1GWAT1ON - R 11 PROPOSE I) RLJi. EXISTING ZONING PC PROPO5ED 7Ot11HG PC ADJACENT PROPERTY ZONING PC ADJACENT PROPERTY LAND USE RL1, RN, AND RuM. TOTAL, BLDG. COVERAGE. ACHES. TOTAL NUMBER OF RESIDENTIAL LOTS — GENERAL DESIG: ALL STREET DESIGN TO CONFORM TO CITY OF CARLSBAD STANDARDS FOR PUB LIC STREETS. STREET WIDTHS AS SHOWN. EASEMENTS AS REQUIRED BY THE CITY ENGINEER. ALL PROPOSED UTIUTITES TO BE UNDERGROUND SLOPE RATIOS ARE CONTINGENT UPON FUTURE SLOPE ANALYSIS BY SOILS ENGINEER. SLOPES SHALL BE NO STEEPER THAN 2:1. DATE OP TOPOGRAPHY MARCH 20, 1986, BY PHOTO GEODETIC CORPORATION. 6 TREE PLANTING AS REQUIRED BY PARKS DEPARTMENT. 7. GRADING QUANTITIES: CUT FILL '. IMPORT: S. • SOILS INFORMATION WAS OBTAINED FROM SOILS REPORTS BY SOUTHERN CALIFORNIA SOILS AND TESTING DATED JANUARY 10, 1984, AND AUGUST 6, 1984; 9. NO PHASING IS PROPOSED. PUBLIC UTUL.ITIES & cISTRICTS: WATER SUPPLY CITY OF CARLSBAD/CMWD SANITARY SEWER CITY OF CARLSBAD -. GAS AND ELECTRICITY SAN DIEGO GAS AND.ELECtRIC . .. TELEPHONE PACIFIC BELL FIRE PROTECTION CITY OF CRLSBAD SCHOOLS CARLSBAD UNIFIED. SCHOOL DISTRIT CRIPTION: LEGAL DES A PORTION- OF LOT OF RANCHO AGIJA HEDIONDA IN THE CITY OF CARLSBAD, COUNTY OF SAN DIEGO, STATE OF CALIFORNIA, ACCORDING TO THE MAP THEREOF NO. 823, VILLAGE"R" [•I1'i1 I 4jI] :Ja] ITA I I] 1 LEGEND BOUNDARY , LIMB BLDG.NtJKflR PAD ELVATIO)l % SLOP* DIUCTIOM OF FLOW SANITARY S*WIR WATIR MAIN STORK DRAIN GLOPBS FIRE HYDRANT STREET LIGHT STREET SIGN EASEMENT LEGEND LEGEND LYON COMMUNITIES INCIF 4330 LA JOLLA VILLAGE DRIVE SXIJ DIEGO, CA 92122 1819)546-1200 PROJECT INFORIVIAT 10' Mal la TRENCH LOCATION -4 • - fr SOUTHERN CAUFORNA . N!Y OIL&TESTINO, INC. sy DSA/ WOW DATE 4-12-90 Josm 9021023 PLATE #1 t -, PREPARED FOR: PREPARED BY: . - -- DAVID So DAVIS DATE DIRECTOR OF PLANNING LYON COMMUNITIES, INC. unsakef A A A iirc #MLM V flM fl1fl 4330 LA JOLLA VILLAGE 'R' DAVID A. HAMMAR R.C.E. 34757 DATE MY REGISTRATION EXPIRES ON 9/30/91 VILLAGE DR. SUITE 130 ssociate sinDi.ge inc SftEET DATE: - IEET - • - SAN DIEGO, CA . io , Hrs,iw r tins '.trerg. i*Ur jO 4 W.0.# A 6-34 ______________________________________ - 92122 819-546-1200 SCALE: i 100' Liquid Limit CL less than 50 OL SILTS AND CLAYS MH Liquid Limit CH greater than 50 OH HIGHLY ORGANIC SOILS PT SUBSURFACE EXPLORATION LEGEND UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION GROUP SYMBOL IYP!:AL NAMES I. COARSE GRAINED, more than half of material is larger than No. 200 sieve size. GRAVELS CLEAN GRAVELS GW Well grade ;ravels, gravel- More tnan half of sand mixtres, little or no coarse fraction is fines. larger than No. 4 GP Poorly graced gravels, gravel sieve size but sand mixtures, little or no smaller than 3'. fines. GRAVELS WITH FINES GM Silty gravels, poorly graded 'Appreciable amount gravel-sand-silt mixtures. of fines) GC Clayey gravels, poorly graded gravel-sand, clay mixtures. SANDS CLEAN SANDS SW Well graded sand, gravelly More than half of sands, 11::le or no fines. coarse fraction is SP Poorly ;ra sands, gravelly smaller than No. 4 sands, iit:e or no fines. sieve size. SANDS WITH FINES SM Silty sands, poorly graced (Appreciable amount sand and silty mixtures. of fines) SC Clayey sands, poorly graced sand and clay mixtures. Inorganic sits and very fine sands, rock flour, sandy silt or clyey-silt-sand mixtures with slight plas- ticity. Inorganic cl ays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. Organic silts and organic silty clays or low plasticity. Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorqaric clays of high plasticity, fat clays. Organic clays of medium to hign plasticity. Peat and other highly organic soils. II. FINE GRAINED, more than I half of material is smaller than No. 200 sieve size. SILTS AND CLAYS ML r - Water level at time of excavation or as indicated US - Undisturbed, driven ring sample or tube sample SOUTHERN CALIFORNIA SOIL &TESTING,INC. CK - Undisturbed chunk sample BG - Bulk sample SP - Standard penetration sample l L CALAVERAS HEIGHTS VILLAGE R ey: DBA TDAT;~ 4-12-90 JOB NUMBER: 9021023 1 Plate - ass SM 3rown. iisc. :',~dium Dense, .ilt.' 'and (ToosoiL Sc, :'ottlad Brown-ourole-white, oist. ediurn CL Dense to Dense, Clayey Sand/Sandy Clay (Paleosol) .r ) p3.4 : SM Buff White, Moist, Uense, Silty Sand 9 (Santiago Formation) T. 111.6 11.8 10 - ench Ended :it LI Feet SOUTHERN CALIFORNIA SOIL & TESTING I INC. 5550 SIVSRDALS .,mu•T SAN 01500, CA&.IORNIA 50150 Calaveras Hills Carlsbad, California DATE CR 12-16-82 14112 Plate No. 3 TRENCH :.:o. TR1-29 3 ) 7 Class Dpqrrinrinn SM, Brown, Moist, Medium Dense, Clavev SC Silty Sand (Topsoil) CL Green/Cray/Brown, Moist, Stiff, Silty Clay (Weathered Santiago Formation: • SM Buff White, Moist, Medium Dense, : : ....% Silty Sand (Santiago Formation) Dense Yellow-Brown • • • Trench Ended at 10 Feet SOUTHERN CALIFORNIA I Calaveras Hills son.. & TESTING INC. I S•SD RIV•PDALSSTREET I Carlsbad, California SAN 01111010, CALIFORNIA 55150 I 12-16- 14112 Mate No. 4 TRENCH NO. TR1-30 r: 1 asc Description M / Sc, CL Gray-brown, Moist, !edium Dense. Clayey Sand/Sandy Clay(Alluvium) / 102.4 21.5 4.________ SC Gray/Brown/Yellow, Moist, Medium Dense, - Clayey Sand (Weathered Santiago Formation) 106.7 14.5 7 10 93.9 22.2 11 - 12 Trench Ended at 12 Feet SOIL. & TESTING, INC. 1+> SOUTHERN CALIFORNIA 5550 RIVURDALU SINUS? SAN 01500, CALIDMNIA **INC Calaveras Hills Carlsbad, California V CR3 12-16-82 DB NO. 14112 Plate No. 5 C1 cc flerinticn SM Brown, :1oist, Medium Dense, Silty sand (Topsoil) SM Yellow-brown. Moist, Medium Dense, Silty Sand (Weathered Santiago Formation) SM Buff White, Moist, Dense, Silty Sand (Santiago Formation) 4 5 1 b 3 7 E1 108.3 11.7 TRENCH ::o. TR1-1 Trench Ended at 9 Feet SOUTHERN CALIFORNIA BOIL & TESTING INC. ua RIVURDALU •YR•Y AN DIUDD, CALIPDRNIA •iuo Calaveras Hills Carlsbad, California 14112 a'JE 12-i Plate No. 6 RECH ::o. 7R1-32 8 10 rl Q czc npqrrinrinn S! Brown, oist. ediurn Dense, Silty Sand (Topsoil) SN Buff %'hite, Moist. Dense, Silty Sand - I : (Santiago Formation Light Green-brown I: Trench Ended at 10 Feet 3 4 ) 7 115.2 13.7 SOUTHERN CALIFORNIA BOIL & TESTING, INC. Ij' ••o RIVEROALM •TR•SY AN oluQa, CALIPORNIA •uiue Calaveras Hills Carlsbad, California CRB 14112 Plate No. 7 GRAIN SIZE .ANALYSIS AND ATTERBURG LiMITS jTR1-.6 TR1-28 TR1-31 1TR1- 32 7?.g? SAMPLE 6" 4,' 3,' 2" 1, "2 Cl) 14 C 8 Mu cr W U) z U. U #1 8 15 bt #16 I #100 #200 cc .05mm lu .005mm .001 mm TP-20 jTQ-23 100 93.5 89.3 81.6 73.6 100 62.2 99.9 100 79.1 99.9 34.1 . 51.9 99.8 22.8 35.5 99.4 18.8 26.5 42.7 12.1 20.4 48.6 9.8 16.8 . 31.3 99.4 100 83.6 100 i 98.5 69.5 99.5 95.6 48.0 48.1 92.9 30.0 J 80.5 89.3 17.6 J 36.2 61.9 11.0 17.9 I 33.5 I . I LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX I UNIFIED I CLASSIFICATION SM/SW SM ISM/SC SM SM SM .1 SOUTHERN CALIFORNIA SOIL. & TESTING LAB, INC. BY DBA u•ua NIVRDAI.0 RTRUY <iT BAN 01USD, CALIPDRNI* JOB NO. 14112 DATE _1-11-83 Plate Nn. GRAIN SIZE ANALYSIS AND ATTERBURG LIMITS LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX I UNIFIED I CLASSIFICATION I SM SC SM SM/Sc SM SM 'I SOUTHERN CALIFORNIA SOIL & TESTING LAB, INC. ••a RIVSRDALS uy.T AN as•sa, CALIDNIA •i.a DEA JOB NO. 14112 DATE 1-11-83 P1tø Jr 0 MAXIMUM DENSITY & OPTIMUM MOISTU R E C O N T E N T ASTMD.155.7.78 Method;...A............ SAMPLE DESCRIPTION Maximum Density (pcf) Optimum Moisture Cont.(°Io) L-7 @ 8'-9' Buff White, Silty Sand 114.0 14.0 ?-13 @ 2'-3' Yellow-brown, Silty Gravely Sand 114.8 13.8 u'-14 @ 2'-3' Green-brown, Sandy Sitly Clay 114.0 15.0 '-14 @ 4'-5' Yellow/Red-brown, Silty Sand 112.6 14.8 TP-20 @ 3'-4' Gray, Silty Sandy Gravel . 128.4 11.7 1-23 @ 8'-9' Yellow-brown, Silty Sand Sandy Silt 120.0 13.3 :1-28 @ 41-5' Buff White, Silty Sand 126.8 9.9 .1-31 @ 5'-6' Buff White, Silty Sand 117.8 13.5 -38 @ 7'-8' Yellow-Gray-brown, Clayey Silty Sand .128.2 11.5 TT-47 @ 2'-3' Yellow-brown, Silty Sand 122.7 12.0 SOUTHERN CALIFORNIA Calavera Hills SOIL & TESTING LAB, INC. Carlsbad, California .a•o RIV.RDALE STREET SAN DIEQD, CALIFORNIA 55150 BY DBA DATE 1-11-83 JOB NO. 14112 Plate No. 10 EXPANSION TEST RESULTS SAMPLE 11-5 @ 6' P-14 @ 2'-5' TP-14 @ 4'.-5' TP-16 @ 3' TR1-2 M 3 - DN DII ION Remolded and Air Dried Remolded and Air Dried Air Dried Air flrierf Remolded and Air Dried - ITIAL M.C.(°/o) 11.3 16.1 14.8 22.8 8.2 .ITIAL DENSITY03CR 116.8 101.3 101.8 00.6 100.5 NAL M.C. ()/•) 23.5 30.5 26.0 30.3 10.4 NORMAL STRESS(PSF- 150 150 150 150 150 (PANS ION (/.) 14.3 1.0 8.3 111.0 2.6 SAMPLE TR1-27 @ 6' TR1-30 @ 2' TR1-30 @ 6' S-38 @ 7'-8' TS-40 @ 2' DII ION Air Dried Air Dried Air Dried Remolded and Air Dried Air Dried 'ITIAL M.C. (0/s) 21.5 14.5 10.7 15.3 14.8 ...TIAL DENSITYPCF 108.3 102.4 106.7 116.3 109.4 'IAL M.C. 19.7 27.6 22.8 15.8 24.6 NORMAL STRESS (PSF 150 150 150 150 1 150 PANS ION (°/.) 5.3 10.5 10.4 3.6 12.7 SOUTHERN CALIFORNIA lcz SOIL & TESTING, INC. CALAVERA HILLS, CARLSBAD, CALIFORNIA BY: DBA IDATE: 1-11-83 JOB NUMBER: 14112 I Plate No. 11 DIRECT SHEAR TEST RESULTS SAMPLE DESCRIPTION AN OF INTERNAL FRICTION (0) COHESION INTERCEPT (psf) ..! at 9' GREEN BROWN SANDY CLAY, REMOLDED TO NATURAL 19 750 at 6' GREEN BROWN SANDY SILTS CLAY 25 300 TI-7 at 6' BUFF WHITE SILTY SAND 33 200 -7 at 8'-9' BUFF WHITE SILTY SAND, REMOLDED TO 90% 31 300 TO-13 at 2'-3 GREEN BROWN SILTY GRAVELY SAND,REMOLDED TO 90% 40 150 -14 at 2'-3 GREEN BROWN SANDY SILTY CLAY, REMOLDED TO 90% 0 500 -14 at 4'-5 YELLOW BROWN SILTY SAND/SANDY SILT.REMOLDED 90% 11 450 u'-20 at 3'-4 GRAY SILTY SANDY GRAVEL, REMOLDED TO 90% 38 200 -23 at 8'-9 YELLOW BROWN SILTY SAND, REMOLDED TO 90% 43 300 61-28 a*t4'-5'BUFF WHITE SILTY SAND, REMOLDED TO 90% 33 200 L 1-28 at 8' BUFF WHITE SILTY SAND 34 300 L1-31 at5'-6 BUFF WHITE SILTY SAND, REMOLDED TO 90% 29 200 ird-31 at 7' BUFF WHITE SILTY SAND 44 150 -38 at 7'-8'YELLOW-GRAY-BROWN,CLAYEY SrLTYSAND REMOLDED 90 37 250 TT-46 at 5' GRAY BROWN SILTY SAND 39. 200 1 -47 at 2'-5 YELLOW BROWN SILTY SAND, REMOLDED TO 90% 42 200 SOUTHERN CALIFORNIA SOIL At TESTING LAB, INC. CALAVERA HILLS, CARLSBAD, CALIFORNIA SSUC RIVSRDALS STRERY SAN QiS3O, CALIFORNIA 52150 14112 Mate No. 12 SLOPE STABILITY CALCULATIONS Janbu's Simplified Slope Stability Method U Tan& Fs:Ncf( C w ) Assume Homogeneous Strength Parameters throughout the slope 1 (°) C(psf) W(pcf) Incl. H (ft) FS I 29 200 120 2:1 30 1.8 1 L 1 I Where: S Angle of Internal Friction C = Cohesion (psf) I Ws = Unit weight of Soil (pcf) H = Height of Slope (ft) FS = Factor of Safety $OUTHIRN CALIFORNIA CALAVERAS HEIGHTS VILLAGE R SOIL & TI$TINQ,INC. my: DBA DAM 4-12-90 JOB NUNSBS:9O2lO23 Plate No. 13 TRANSVERSE 3 3' WEAKENED - PLANE JOINTS 6 ON CENTER 10' 5•-1O• SLABS IN EXCESS OF SLABS' 5 TO 10 10 FEET IN WIDTH FEET IN WIDTH PLAN NO SCALE TOOLED JOINT 10 1-1/4 #5 REBARS AT 18 ON 1/2 CENTER EACH WAY 5" WEAKENED PLANE JOINT DETAIL NO SCALE SOUTHERN CALIFORNIA SOIL & TESTING, INC. CALAVERAS HEIGHTS VILLAGE R - DBA DATEz.. 4-12-90 NUMBERS 9021023 1 Plate No. 14 6• MAX. 6• WATERPROOF BACK OF WALL PER ARCHITECT'S SPECIFICATIONS 3/4 INCH CRUSHED ROCK OR MIRADRAIN 6000 OR EQUIVALENT GEOFABRIC BETWEEN ROCK AND SOIL 4 INCH DIAMETER PERFORATED PIPE . . . . . . .. . . . . 4 . ... . . p. . . / RETAINING WALL SUBDRAIN DETAIL NO SCALE SOUTHERN CALIFORNIA CALAVERAS HEIGHTS VILLAGE R SOIL & TI$TINQ,INC. I?: DBA JOATI: 4-12-90 m • s NuIPR: 9021023 Plate No. 15 - P\tjD1.11Mi I a f,1;!i]W, f,u sJtj* The intent of these specifications is to establish procedures for clearing, 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 recuitiiendations contained in the preliminary geotechnical investigation 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 geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written connu.inication signed by the Geotechnical Engineer. i (0 Southern California Soil and Testing, Inc., shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him appraised 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 geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further reconlieridations. (R-9/89) SCS&T 9021023 April 12, 1990 appendix, Page 2 If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc.; construction should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content - ?S'flI D-1557-78. Density of Soil In-Place - AS1 D-1556-64 or ASTM D-2922. All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. ARATIcl1 OF AREAS TO RIVE FUL All vegetation, brush and debris derived from clearing operations shall be roved, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soils which possesses an in-situ density of at least 90% of its maximum dry density. (R-9/89) SCS&T 9021023 April 12, 1990 Appendix, Page 3 When the slope of the natural ground receiving fill exceeds 20% (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formatio'nal soils. The lower bench shall be at least 10 feet wide or 1-1/2 tines the the equipment width whichever is greater and shall be sloped back into the hillside at a gradient of not less than t (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 herein for compacted natural ground. Ground slopes flatter than 20% shall be benched when considered necessary by the Geotechnical Engineer. 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 described procedures should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water. lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recoiniendation will be necessary. All water walls which will be abandoned should be backfilled and capped in accordance to the requirements set forth by the Geotechnical Engineer. 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 Geotechnical Engineer and/or a qualified Structural Engineer. (R-9/89) SCS&T 9021023 April 12, 1990 Appendix, Paae 4 Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND a11PKrIc!1 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 compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipTent 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 geotechnical 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 achieved. The maximum size and spacing of rock permitted in structural fills and in non-structural fills is discussed in the geotechnical report, when applicable. (R-9/89) SCS&T 9021023 April 12, 1990 Appendix, Page 5 Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by mans of sheepsfoot rollers or other suitable equipment. Compaction by sheeps foot rollers shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been constructed. 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 the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be stable surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problem arise, the Contractor will be notified that day of such conditions by written coninunication from the Geotechnical Engineer or his representative in the form of a daily field report. 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 cost to the Owner or Geotechnical Engineer. (R-9/89) SCS&T 9021023 April 12, 1990 Appendix, Page 6 [si J,Tsjj The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals 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 Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. Field observation by the Geotechnical 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. Neither the presence of the Geotechnical 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 compaction. 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. (R-9/89) SCS&T 9021023 April 12, 1990 Appendix, Page 7 MMW GRADING SPECIFICATIONS - SPECIAL PRMSIONS REIFIVE 4PPerIc1: The minimum degree of compaction to be obtained in compacted natural ground, conpacted fill, and compacted backfill shall be at least 90 percent. For street and parking lot subgrade, the upper six inches should be compacted to at least 95% relative compaction. EXPAINSM SOUS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-C. OVERSIZED IQLIRIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversize materials should not be placed in fill unless recommendations of placement of such material is provided by the geotechnical engineer. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. NITI(X W1: 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 reconpacted as structural backf ill. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required. (R-9/89) RECEIVED FEB 01 '1 ENGINEERING DEPARTMENT 2 2000