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06-3801 (CSCS) Geotechnical Investigation Reportr. GEOTECHNICAL EXPLORATION REPORT PROPOSED RETAIUCOMMERCIAL DEVELOPMENT NEC of HIGHWAY 111 & DUNE PALMS ROAD LA QUINTA, CALIFORNIA ... - .. .. a ._. .... .. .. .. ...... ... _ [DATE Y OF LA QUINTA DING & SAFETY DEPT. OFMdr -, woo OP 710 �tl dL� OCT 2 4 2006 ay February 1, 2005 Mr. Chris Caras Newmark 725 S. Figueroa Street, Suite 2440 Los Angeles, CA 90017 Re: Geotechnical Exploration Report Proposed Retail/Commercial Development NEC of Highway 111 & Dune Palms Road. La Quinta, California PSI Project No. 056-55001 Dear Mr. Caras: Professional Service Industries, Inc. is pleased to submit our Geotechnical Exploration Report for the referenced project. This report presents the results of our field investigation, laboratory testing, and our engineering analysis for preparing recommendations for site preparation, and foundation and pavement design. Enclosed please find two (2) copies of the report. Copies have also been sent to those listed at the bottom of this letter, as requested. We appreciate the opportunity to. perform this Geotechnical Study and look forward to continued participation during the design and construction phases of this project. If you have any questions pertaining to this report, or if we may be of further service, please contact our office. Respectfully submitted, PROFESSIONAL SERVICE INDUSTRIES, INC. Stephanie Montgomery Staff Geologist Enrique A. Riutort, RCE. District Manager RCE 58623 Exp. 12/31/06 Reviewed by: James W. Niehoff Senior Technical Professional Cc: (1) Jeff Lowden . (1) Mark Giles, KKE o ' (i GEOTECHNICAL EXPLORATION REPORT Proposed Retail/Commercial Development NEC of Highway 111 & Dune Palms Road La Quinta, California PSI File No. 056-55001 PREPARED FOR Mr. Chris Caras Newmark 725 S. Figueroa Street, Suite 2440 Los Angeles, CA 90017 February 1, 2005 BY PROFESSIONAL SERVICE INDUSTRIES, INC. 3960 GILMAN STREET LONG BEACH, CALIFORNIA 90815 TABLE OF CONTENTS EXECUTIVE SUMMARY................................................................................................1 PROJECT INFORMATION............................................................................................. 4 • Project Authorization............................................................................................ 4 Project Description................................................................................................ 4 • Purpose and Scope of Services..' .........................:............................................... 4 SITE_ AND SUBSURFACE CONDITIONS...................................................................... 5 • Site Location and Description............................................................................... 5 • Subsurface Conditions......................................................................................... 5 • Groundwater Information...................................................................................... 6 SEISMICITY...............................................................................................I..................... 7 •Seiismicity and.Faulting_................................................................. • Earthquake Design ParaMUM—meters............................................................................ g,,, GEOTECHNICAL EVALUATION.................................................................................10 EARTHWORK RECOMMENDATIONS........................................................................10 • Site Preparation.................................................................................................. 11 • Shrinkage/Swell Factors..................................................................................... 12 t Temporary Excavations........................................................... 12 FOUNDATION AND SLAB RECOMMENDATIONS.....................................................13,. •�- Structural Foundations_....................................................................................... 1-3y • Interior Floor Slab..................................................................................:............ 14, • Static Settlement................................................................................................ 14 • Soil Sulfate Content............................................................................:............... 14 •�av_emen ,Recommendations............................................................................ , NSTRUCTION CONSIDERATIONS........................................................................16 •s Moisture Sensitive Soils/Weather Rel-ate_d_ C_oncerns......................................... J 1,6 • Drainage and Groundwater_Considerations....................................................... 17 Excavations............................................................. 17 • Trench_ Backfill..................................................................................................... ADDITIONALSERVICES.............................................................................................19 REPORTLIMITATIONS...............................................................................................19 FIGURES • Figure 1: Site Vicinity Map • Figure 2: Boring Location Map APPENDICES • Appendix A: References • Appendix B: Exploration Logs •. Appendix C: Laboratory Test Results • Appendix D: Seismic Analysis - Computer Output • Appendix E: Standard Guidelines For Grading Project 1 EXECUTIVE SUMMARY For your convenience, the following paragraphs and tables present the major findings and provide recommendations for the proposed retail/commercial development in La Quinta, California. To provide for uniform support of the new structure, overexcavation and recompaction of near-surface soils is recommended for both slab and foundation support. The existing fill materials should be completely removed .within the building pad area. Provided the overexcavation is performed, the structure can be supported on shallow spread footing foundations. The recommended depth -of overexcavation is approximately 36 inches below the bottom of proposed footings. The recommended depth of overexcavation for parking areas is 12 inches below existing grade. The native soils may represent a moderately corrosive environment with respect to concrete.' Type 11 cement with a maximum water-cement ratio of 0.50 is minimally recommended for concrete in contact with the ground. The final concrete mix design should be evaluated after sulfate testing is performed on actual subgrade materials. The regional seismicity is comparable to the rest of southern California. The nearest potentially active fault is the San Andreas Fault — Southern Segment, located approximately 5.1 miles (8.2 km) from the site. The site is not located within a currently established Alquist-Priolo Earthquake Study Zone. The site is not located within a seismic- hazard zone for liquefaction potential. The Uniform Building Code should be followed with respect to seismic design. Table 1 presents a summary of our recommendations. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 2 TABLE 1 SUMMARY OF RECOMMENDATIONS Design Item Recommended Design Parameter FOUNDATIONS: Allowable Bearing Pressure 2,000 psf Minimum Footing Width 15 inches continuous footing 24 inches isolated spread footing Minimum Footing -Embedments 18 inches Minimum Reinforcement Structural engineer to design for low expansion potential Estimated Foundation Settlement 1 inch total/ 1/2 inch differential Cement Type & Water -Cement Ratio Type II & 0.50 PAVEMENTS: Asphalt Concrete Pavement: Parking Areas 3.0" over 4.0" Class 2 AB Heavy Traffic 3.0" over 6.0" Class 2 AB PCC Pavement: Light Traffic 5.0" over 4.0" Class 2 AB Heavy Traffic 6.0" over 4.0" Class 2 AB CONCRETE SLABS: Interior/Exterior: Slab Subgrade Preparation As recommended in report text Minimum Reinforcement Structural engineer to design for low expansion potential PROJECT SITE CONDITIONS: Soil Sulfate Content Moderate Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. u Design Item Recommended Design Parameter Expansive Nature Of Site Soils Low expansion potential Groundwater Depth Encountered Not encountered r Proposed Retail/Commercial Development, La Quinta, CA 3 Professional Service Industries, Inc. PROJECT INFORMATION Project Authorization 4 Professional Service Industries, -Inc. (PSI) has completed a geotechnical exploration for a proposed retail/commercial to be located on the northeast corner of Highway 111 and Dune Palms Road, in La Quinta, California. Authorization for the geotechnical services was issued by Chris Caras of Newmark on January 15, 2005. Project Description Project information in the form of a conceptual site plan and oral discussion was provided by Newmark. Based on our review of the provided information, we understand the proposed construction will include the following: Construction of four single -story, slab -on grade buildings between 8,600 and 10,000 square foot in plan in the northern three acres, A paved parking lot; Underground utilities and other associated improvements. The presently vacant six -acre parcel will be developed as northern and southern portions, each three acres. The northern three acres will be developed with the four proposed buildings and parking and driveway areas: The southern three acres will be developed in the future. Preliminary plans call for the proposed buildings to be supported by conventional shallow foundations with maximum column and wall loads on the order of 120 kips and 3.5 kips per linear foot, respectively. The geotechnical recommendations presented in this report are based on the provided project information, proposed building location, and the subsurface materials described -in this report. - If any of the noted..information is incorrect, please inform PSI in writing so that we may amend recommendations presented in this report if appropriate. PSI will not be responsible for its recommendations when it is not notified of changes in the project. Purpose and Scope of Services The purpose of this study was to explore the subsurface conditions at the site to enable_ an evaluation of acceptable foundation systems for the proposed construction. This report briefly outlines the testing procedures, describes the site and subsurface conditions, Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 5 and presents geotechnical recommendations for foundation design and for general site development. Our scope of services included drilling seven test borings at the site. Additional work included appropriate laboratory testing and preparation of this geotechnical report. This report briefly outlines the testing procedures, presents available project information, describes the site and subsurface conditions, and presents preliminary recommendations regarding the following: • Grading procedures for site development; • Foundation types, depths, allowable bearing capacities, and an estimate of potential settlement; - • Comments regarding factors that will impact construction and performance of the proposed construction. Our scope of services did not include an environmental assessment for determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, bedrock, surface water, groundwater, or air on or below, or around this site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes. SITE AND SUBSURFACE CONDITIONS Site Location and Description The proposed buildings will be located within an existing commercial area at the northeast comer of Highway 111 and Dune Palms Road, in the City of La Quinta. The site is currently vacant of structures. The site is bounded by Highway 111 to the south, Dune Palms Road to the•west, -an irrigation channel to the north, and existing retail/commercial properties to the east. Subsurface Conditions The subsurface conditions at the site were explored with seven soil test borings. Four of the borings were drilled within the proposed building pads for the buildings in the northern three acres and the remaining three borings were drilled within the southern three acres, with one boring in each acre. The borings within the building pads were drilled to approximate depths ranging between 20 and 50 feet below existing grade, and the borings within southern three acres were drilled to an approximate depth of 20 feet below existing Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. C:9 grade. All the test borings were advanced using hollow stem auger drilling methods and representative undisturbed soil samples were collected. Drilling and sampling techniques were accomplished generally in accordance with ASTM procedures. As observed in our exploratory borings, the subject site is mantled by alluvial deposits, which extend at least to the maximum explored depth of approximately 50 feet below existing site grade. The alluvium consisted of light and dark brown sands (SP), silty sands (SM) and silts (ML). These materials were noted to be dry to slightly moist and very loose/stiff to very. dense/hard at the time of our exploration. The near -surface soils are considered to have a low expansion potential (UBC 18-2). The above subsurface description is of a generalized nature to highlight the major subsurface stratification features and material characteristics. The boring logs included in the Appendix should be reviewed for specific information at individual boring locations. These records include soil descriptions, stratifications, penetration resistances, locations of the samples and laboratory test data. The stratifications shown on the boring logs represent the conditions only at the actual boring locations at the time of our exploration. Variations may occur and should be expected between boring locations. The stratifications indicated on the boring logs represent the approximate boundaries between subsurface materials. The actual transitions may be gradual. Water level information obtained during field operations is also shown on these boring logs. The samples which were not altered by laboratory testing will be retained for approximately 60 days from the date of this report and then will be discarded. Select soil samples were tested in the laboratory to determine materials properties for our evaluation. Laboratory testing was accomplished generally in accordance with ASTM procedures. A brief discussion of the laboratory tests performed and the results of our testing are presented in Appendix C. Groundwater Information Groundwater was not encountered during our field exploration to the maximum explored depth of approximately 50 feet below ground surface. It should be noted, however, that seasonal fluctuations in groundwater levels may occur. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. SEISMICITY Seismicity and Faulting 7 Regional Seismicity — Generally, seismicity within California can be attributed to faulting due to regional tectonic movement. This includes the San Andreas Fault and other sub=parallel strike -slip faults, as well as normal and thrust faulting within the State. The area of the subject site is considered seismically active. The subject site is situated in the UBC Seismic Zone 4. Seismic hazards within the site can be attributed to. potential ground shaking resulting from earthquake events along nearby or more distant faulting.. - According to the. regional geologic literature, the closest known Late Quaternary fault is the San Andreas Fault — Southern Segment, located approximately 5.1 miles (8.2 km) from the site. Several potentially active and Pre -Quaternary faults also occur within the regional vicinity. Seismic Analysis — The seismicity of the site was evaluated utilizing deterministic methods for active Quaternary faults within the regional vicinity. According to the Alquist- Priolo Special Studies Zones Act of 1972 (revised 1993) Quaternary faults have been classified as active faults which show apparent surface rupture during the last 11,000 years (i.e., Holocene time). This site is not within a currently mapped Earthquake Fault Zone (Hart and Bryant, 1992). Deterministic seismicity at the site was evaluated with the Eqfault computer program (Blake, 1995), which . utilizes a digitized map (updated 1998) of known Late Quaternary earthquake faults, a catalog of the estimated credible and potential earthquakes for each fault, and a user specified attenuation relationship (Campbell & Bozorgnia, 1997). The fault database includes additional Quaternary faults that may be potentially active according to some researchers, although these faults may not be considered • active -as'-determined by the 1997 Uniform Building Code. Output -from the. - Egfault program is presented in Appendix D. Historical Seismicity — Three significant historical events (7.1 M or greater) have affected the site vicinity during this century. They are as follows: • Hector Mine Event - On October 16, 1999 a magnitude 7.1 ML earthquake occurred -within the Bullion Mountains (Toppozada 2000). • Landers Event - On June 28, 1992, the Yucca Valley was subjected to the largest seismic event to strike Southern California in 40 years. The Landers earthquake had a main shock magnitude MS 7.5 (7.3 MW). Surface rupture occurred just Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. A south of the town of Yucca Valley and extended some 70 km (43 mi.) towards Barstow along portions of Camp Rock -Emerson, Johnson Valley, and Homestead Valley Fault systems. Surface horizontal offsets attained a maximum of 21 feet (OSMS 1992). • Big Bear Event - Some three hours after the Landers event of June 28, 1992, a magnitude 6.6 MS event occurred 10 mi southeast of Big Bear Lake. The earthquake occurred on a previously unknown fault trending northeast from the San Andreas Fault in the San Bernardino Mountains (OSMS 1992). . Seismic Hazard Assessment :- Although earthquake predictions of time, place, and magnitudes have not been scientifically developed, significant geologic information and statistical analysis have been compiled, intensely analyzed, and published by various agencies over the past 25 years. The primary seismic source nearby to the project site is the San Andreas Fault — Southern and Coachella Segments, which lie approximately 5.1 to 5.5 miles (8.2 to 8.8 km) from the site. • Ground motion: The primary seismic hazard at the project site is strong ground motion from earthquakes along nearby active faults. The Maximum Credible Earthquake is defined as the maximum earthquake that appears capable of occurring under the presently known tectonic framework. Based on our analysis, the site is subject to an MCE magnitude of 7.4 along the San Andreas Fault — Southern Segment with a corresponding median Peak Ground Acceleration of 0.42g, and 84th percentile (one standard deviation) PGA of 0.62g. The Design Basis Earthquake (DBE) is based on 10% probability of exceedance in - 50 years. Based on CGS seismic ground motion analysis for the latitude -longitude at the site, the ground motions representing the DBE are shown in the table below: 10%PE in 50 yr PGA 0.593 0.2 sec SA 1.329 1.0 sec SA 0.772 PGA = Peak Ground Acceleration PE = Probabilistic Exceedance SA = Spectral Acceleration period length. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. E Lurching and Shallow Ground Rupture: The project site does not lie within a State of California, Alquist-Priolo Earthquake Fault Zone. Fault rupture is not anticipated to occur at the project site because of the well -delineated fault lines through this region. However, due to the active seismicity of California, this possibility cannot be completely ruled out. In this light, the unlikely hazard of lurching or ground -rupture should not preclude consideration of "flexible" design for on-site utility lines and connections. Landsliding: Seismically induced landsliding is not considered a hazard on, or adjacent to the site. This conclusion is primarily based on the lack of hillsides or slopes on. or adjacent to the site. No evidence of prior landsliding was .observed on the site during our investigation, despite several historic seismic events. Liquefaction and Seismically Induced Settlement: Liquefaction and seismically induced settlement typically occur in loose granular soils with groundwater near the ground surface. During an earthquake, ground shaking causes the soil to collapse and the groundwater to rapidly rise to the surface, resulting in a sudden loss of soil bearing strength. Fine-grained soils are not generally susceptible to liquefaction or to short-term settlement due to seismic loads. Groundwater was not encountered during our field exploration to the maximum explored depth of approximately 50 feet below ground surface. Tsunamis and Seiches: Inundation by tsunamis (seismic or "tidal waves") or seiches ("tidal waves" in confined bodies of water) are not considered to be a significant threat to the subject site due to the absence of proximal large bodies of water. Earthquake Design Parameters A review of the 1997 Uniform Building Code Maps of Active Fault Near -Source Zones indicates that the nearest fault is the San Andreas Fault — Southern Segment, located approximately 2.0 miles (3.3 km) away. Ground shaking from this fault and the other potentially active and Pre -Quaternary faults in the region is the most likely event that will affect the site. The site is located within UBC Seismic Zone 4. In conjunction with the soil classifications provided in Table 16-J of the 1997 UBC, our field exploration indicates that the geologic subgrade at the subject site can be characterized as soil profile type SD. The proposed structure should be designed in accordance with seismic design requirements of the UBC 1997 edition, Volume II, Chapter 16, utilizing the following criteria: Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. '`✓ UBC Chapter 16 Seismic Parameter Value Table 16-1 Seismic Zone Factor, Z 0.4 Table 16-J Soil Profile Type Spm,,, Table 16-Q Seismic Coefficient, Ca 0..47x. Table 16-R Seismic Coefficient, C„ 0.86. Table 16-S Near Source Factor, Na 1...1 Table 16-T Near Source Factor, N„ 1_3 Table 16-U Seismic Source Type A � 10 In addition, design of structures should of the governing jurisdiction's building codes and standard practices of the Structural Engineers Association of California. GEOTECHNICAL EVALUATION As previously discussed, the primary geotechnical issue at the site that will affect the construction of the proposed structure is the presence of some loose material across the proposed building pads and parking areas. Based upon the assumed column loads, the proposed structure can be supported on conventional shallow foundations, provided that they are entirely supported by properly compacted fill. The existing fill materials should be excavated, moisture conditioned, then replaced as uniformly compacted fill to provide for uniform bearing across the building pad. The recommended depth of overexcavation is approximately 36 inches below bottom of footings. The recommended depth of overexcavation for parking areas is 12 inches below existing grade or finished grade, which ever is deeper. EARTHWORK RECOMMENDATIONS The proposed construction at the site should be performed in accordance with the following recommendations and the standard guidelines for grading projects included in Appendix E. In case of conflict, the following recommendations should supersede those in r the Appendix. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 11 Site Preparation Initially, all existing structures, pavements, utilities and deleterious material should be removed from areas proposed for construction. Stripping operations should extend a minimum of 10 feet beyond the proposed building limits, where practical. To assist in the mitigation of potentially compressible layers and also to provide for a more uniform foundation base, it is recommended that the existing near -surface soils be removed and replaced as properly compacted fill in areas that are to receive buildings or other settlement sensitive structures. Based upon the results of our subsurface exploration, the required excavation is anticipated- to extend approximately 36 inches below.the bottom of footings. The required excavation for parking areas is 12 inches below existing grade or finished grade. The exposed subgrade below the removal depth should be moisture conditioned, proof rolled and densified using a heavy vibratory drum roller. The removed soils should be moisture conditioned to at least 3 percent above optimum moisture content, or more as needed to achieve at least 90 percent relative compaction (based on ASTM Test Method D1557) until design finish grades are reached. This earthwork should extend laterally at least four feet beyond the building limits, whenever practical. The first layer of fill material should be placed in a relatively uniform horizontal lift and be adequately keyed into the stripped and scarified (to at least 12 inches) subgrade soils. Fill materials, including import soil, should be free of organic or other deleterious materials, have a maximum particle size of 3 inches or less and should possess an expansion index of less than 20 (UBC 18-2). Most of the on sites soils appear to be reusable as structural fill. During the course of grading operation, oversized material (particles greater than 3 inches) may be generated. These materials should not be placed within the compacted fill. Structural fill should be compacted to at least 90 percent of the maximum dry density as determined by ASTM Designation D1557. Fill should be placed in maximum loose lifts of 8 inches and should be moisture conditioned and compacted to at least 3 percent above the optimum moisture content, or more as needed to achieve 90 percent relative compaction. If water must be added, it should be uniformly applied and thoroughly mixed into the soil by disking or scarifying. Each lift of compacted -engineered fill should be tested by a representative of the geotechnical engineer prior to placement of subsequent lifts. The edges of compacted fill should extend 1.0 feet beyond the edges of buildings prior to sloping. Non-structural fill adjacent to structural fill should be placed in unison to provide lateral support. Backfill along building walls must be placed and compacted with care to Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. minimize the ' development of excessive unbalanced lateral pressures. The type of fill material placed adjacent to below grade walls must be properly tested by the geotechnical engineer with consideration for the lateral earth pressure used in the wall design. As discussed in the Subsurface Conditions section of this report, alluvial deposits underlie the site. As such, it is anticipated that shallow to moderate excavations can generally achieved with conventional earthmoving. equipment. In pavement areas, the upper 12 inches of finish subgrade should be removed / scarified; moisture conditioned to at least 3 percent above optimum moisture and -compacted to at least 95 percent relative compaction based on Test Method D1557. The upper 12 -inch densification should be performed immediately prior to the placement of base material and not during the initial grading operation. All grading operations should be performed in accordance with the requirements of the Uniform Building Code (1997 edition), PSI's Standard Guidelines for Grading Projects (Appendix E), and local governmental standards which have jurisdiction over this project. Shrinkage/Swell Factors Shrinkage and swell factors are a preliminary estimate of the volume change of the excavated onsite materials, upon recompaction as engineered fill. The actual shrinkage/swell factors are dependent on soil type, location, and compactive effort. As discussed in the Subsurface Conditions section of this report, alluvium deposits underlie 'the site. Based on a comparison between in-situ densities and the laboratory maximum density (ASTM D1557-00), the soils are estimated to undergo shrinkage on the order of 2 to 4 percent during grading operations, with no appreciable swell expected. Temporary Excavations Temporary construction excavations may be cut to a near vertical grade without shoring to a maximum depth of 4 feet. For deeper cuts, the surface above 4 feet should be properly sloped back to a grade of at least 1 to 1 (horizontal to vertical) or flatter.. Groundwater is not expected to pose a problem during grading. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 3 FOUNDATION AND SLAB RECOMMENDATIONS Structural Foundations Conventional continuous and isolated spread footings are suitable for structural support of the proposed one-story structure loads. Footings are anticipated to be entirely supported by properly compacted fill materials. Continuous footings which are at least 15 inches e wide_ and -supported_ at _a _depth of at ' least 18 inches below the lowest, adjacent fin-1_ishgrade, may be designed for an all5wa6leb�earing,pressureof_2,000,psf. Isolated spread footingswhich=are atleast 24`inches wide and also supported at_a depth of at_least o mcnes peiow me io__we� sia facent..graae, may also ae designed for an allowable bearing pressure of 2,OO psf. The allowable soil bearing values may be increased by one-third for y loads of short duration, including wind and. seismic forces. Appropriate 'foundation reinforcement should be provided in accordance with the Structural Engineer's design based upon a low expansion potential. Resistance to lateral loads may be calculated by any rational method that incorporates sliding friction and/or passive earth pressure. An allowable friction coefficient of 0.35 may be utilized at the concrete -soil interface. The design may incorporate an allowable passive earth pressure of 250 psf/ft below a depth of 1 foot, provided that the footing concrete is poured tightly against properly compacted fill materials. No reductions are necessary when combining the frictional and passive resistance of the soils to determine the total lateral resistance. The foundation excavationsshouldbe observed by a representative of PSI prior to steel or concrete placement to assess that thefoundations rr aterials "are apable of supporting the design loads and are consistent with the materials discussed in this report. Soft or loose soil zones encountered at the bottom of the foundation excavations should be removed as directed by the geotechnical engineer. Cavities formed as a result of excavation of soft or loose soil zones should be -backfilled with lean concrete or -dense graded compacted crushed stone. After opening, foundation excavations should be observed and concrete placed as quickly as possible to avoid exposure of the foundation bottoms to wetting and drying. Surface run-off water should be drained away from the excavations and not be allowed to pond. If possible, the foundation concrete should be placed during the same day the excavation is made. If it is required that foundation excavations be left open for more than one day, they should be protected to reduce evaporation or entry of moisture. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 4 Interior Floor Slab The floor slab should be supported on properly compacted structural fill. The slab section may be designed by the structural engineer using a coefficient of subgrade reaction of 70 pci and assuming a low expansion potential (UBC 18-2) for the near -surface soils at the site. Based on geotechnical considerations, -it is recommended that the interior slabs be at least 5 inches in nominal thickness, and rein orced in accordance wi h the structural engineer's requiremen s. Slabs should be underlain by a capillary break of a thickness of at least_4 nchesI consisting of clean sand or fine. gravel with a 10 -mil visqueen sheet placed midheight within the capillary break material. The visqueen s eet s ould be sealed along the edges to prevent lateral migration of soil moisture from adjacent non-visqueen areas. Prior to placement of clean sand and slab -on -grade, the visqueen sheet should be thoroughly inspected for cracks, punctures, tears, and holes. If necessary, the visqueen should be replaced or patched to assure a fully functional entity. Some minor cracking of slabs can be expected due to shrinkage. The potential for this slab cracking can be reduced by careful control of water/cement ratios in the concrete. The contractor should take appropriate curing precautions during the pouring of concrete in hot weather to minimize the cracking of slabs. We recommend that a slipsheet (or equivalent) be utilized if grouted fill, tile, or other crack -sensitive floor covering is planned directly on concrete slabs. All slabs should be designed in accordance with structural considerations. Static Settlement Based on the known subsurface conditions and site geology, and our experience, we anticipate that properly designed and constructed foundations supported on the recommended compacted -fill •materials should experience maximum total and differential static settlements of less than 1 -inch and Y2- inch, respectively. While settlement of this magnitude is generally considered tolerable for structures of the type proposed, the design of masonry walls should include provisions for liberally spaced, vertical control joints to minimize the effects,of cosmetic "cracking". Soil Sulfate Content A representative sample of onsite soils was tested in our laboratory for sulfate content. Results of testing indicate that the onsite soils may have"negli i� ble; sulfate content with - respect to concrete corrosion. For preliminary design purposes, we Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 15 recommend a minimum of Type II cement and a maximum water -cement ratio of 0.50 (by weight), for concrete in contact with on-site soils. Final concrete mix design should be evaluated after sulfate tests have been performed on the actual subgrade material. Concrete mix design should follow the minimum requirements of Table 19-A-4 of the 1997 Uniform Building Code. Pavement Recommendations The recommended thicknesses presented below are considered typical and minimum for the assumed parameters. We understand that budgetary. considerations sometimes warrant thinner pavement sections than those presented. However, the client, the owner, and the project principals should be aware that thinner pavement sections might result in increased maintenance costs and lower than anticipated pavement life. The appropriate pavement section depends' primarily upon the type of subgrade soil; shear strength, traffic load, and planned pavement life. For preliminary purposes, we have assumed traffic indices of TI=5.0 for parking areas and TI=6.5 for those driveway and truck lanes subject to relatively heavy traffic. These assumed traffic indices should be verified by the project -civil engineer prior to construction. For preliminary purposes, we have assumed an R -value of 30 for the near -surface soils within pavement areas. Since an evaluation of the characteristics of the actual soils at pavement subgrade can only be provided at the completion of grading, the following pavement sections should be used for planning purposes only. Final pavement designs should be evaluated after R -value tests have been performed on the actual subgrade material. Pavement Loading Conditions. Assumed Traffic Index Preliminary Pavement Section Parking Areas 5.0 3.0 inches A.C. over 4.0 inches Class 2 Aggregate Base 3.0 inches A.C. over 6.0 inches Heavy Traffic 6.5 Class 2 Aggregate Base Where rigid concrete pavements are planned to support vehicular traffic, the following minimum sections are recommended: Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries. Inc. 16 Pavement Loading Conditions Assumed Traffic Index Preliminary Pavement Section Light Traffic 5.0 5.0 inches PCC over 4.0 inches Class 2 Aggregate Base Heavy Traffic 6.5 6.0 inches PCC over 4.0 inches Class 2 Aggregate Base Portland Cement Concrete pavement sections should incorporate appropriate steel reinforcement and crack control joints as designed by the project structural engineer. We recommend that sections be as nearly squared as possible and no more than 12 feet on a side. A 3,500 psi mix may be utilized. The actual design should also be in accordance with design criteria specified by the governing jurisdiction. Asphalt Concrete (A.C.), Portland Cement Concrete, and Class 2 aggregate base should conform -to and be placed in accordance with the latest revision of the California Department of Transportation Standard Specifications and American Concrete Institute (ACI) codes. Aggregate base should be compacted to a minimum of 95 percent relative compaction (based on ASTM Test Method D1557) prior to placement of A.C. Subgrade preparation for pavement areas is included in the Site Preparation section of this report. CONSTRUCTION CONSIDERATIONS It is recommended that PSI be retained to provide ,�obseryat_ i n and .testing of construction -activities involved in the foundation, earthwork, and related activities•of this: project. PSI cannot accept any responsibility for any conditions which deviate from those described in this report, nor for the performance of the foundation if not engaged to also provide construction observation and testing for this project. Moisture Sensitive Soils/Weather Related Concerns . The upper soils encountered at this site may be sensitive to disturbances caused by construction traffic and to changes in moisture content. During wet weather periods, increases in the moisture content of the soil can cause significant reduction in the soil strength and support capabilities. In addition, soils which become wet may be slow to Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. 17 dry and thus significantly retard the progress of grading and compaction activities. 11 will, therefore, be advantageous to perform earthwork and foundation construction activities during dry weather. Much of the on-site soils may be susceptible to erosion during periods of inclement weather. As a result, the project Civil Engineer/Architect and Grading Contractor should take appropriate precautions to reduce the potential for erosion during and after construction. Drainage and Groundwater Considerations Groundwater was not encountered during -our field exploration the maximum .explored depth of approximately 50 feet below ground surface. It should be noted, - however, that variations in the ground water table may result from fluctuation in the ground surface topography, subsurface stratification, precipitation, irrigation, and other factors that may not have evident at the time of our exploration. This sometimes occurs where relatively impermeable and/or cemented formational materials are overlain by fill soils. In addition, during retaining wall excavations, seepage may be encountered. We recommend that a representative of PSI be present during grading operations to evaluate areas of seepage. Drainage devices for reduction of water accumulation can be recommended if these conditions occur. Water should not be allowed to collect in the foundation excavation, on floor slab areas, or on prepared subgrades of the construction area either during or after construction. Undercut or excavated areas should be sloped toward one corner to facilitate removal of any collected rainwater, groundwater, or surface runoff. Positive site drainage should be provided to reduce infiltration of surface water around the perimeter of the building and beneath the floor slabs. The grades should be sloped away from the building and surface drainage should be collected and discharged such - that water- isnot permitted to infiltrate the backfill and floor slab areas of the -building-.- . Excavations In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its "Construction Standards for Excavations, 29 CFR, part 1926, Subpart P". This document was issued to better insure the safety of workmen entering trenches or excavations. -It is mandated by this federal regulation that excavations, whether they be utility trenches, basement excavation or foundation excavations, be constructed in accordance with the OSHA guidelines. It is our understanding that these regulations are Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. M being strictly enforced and if they are not closely followed the owner and the contractor could be liable for substantial penalties. . The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's "responsible person", as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth,.exceed those specified in local, state, and federal safety regulations.. We are providing this information solely as a service to our client. PSI does not assume responsibility for construction site safety or the contractor's or other parties' compliance with local, state, and federal safety or other regulations. Trench Backfill Except where extending perpendicular under proposed foundations, utility trenches should be constructed outside a 1:1 projection from the base -of -foundations. Trench excavations for utility lines, which extend under structural areas should. be properly backfilled and compacted. - Utilities should be bedded and backfilled with clean sand or approved granular soil to a depth of at least 1 foot over the pipe. This backfill should be uniformly watered and compacted to a firm condition for pipe support. All required trench backfill should be mechanically compacted in layers to at least 95% of maximum dry density based on ASTM D1557. Flooding should not be permitted. The remainder of the backfill shall be typical on-site soil or imported soil which should be placed in lifts not exceeding 8 inches in thickness, watered or aerated to -at least 3 percent above the optimum moisture content, and mechanically compacted to at least 90 percent of maximum dry density (based on ASTM D1557). Some settlement of the backfill may be expected and any utilities within the trenches. or concrete walks supported on the trench backfill should be designed to accept these differential movements. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. I ADDITIONAL SERVICES The recommendations made in this report are based partially on the assumption that an adequate program of tests and inspections will be performed during construction to verify the field applicability or subsurface conditions and compliance with the recommendations that are the basis of this report. The firm that provides testing and observation during construction shall assume the responsibility of the geotechnical consultant of record, performing additional investigation and testing as needed to determine the appropriate foundations and soil preparation to be used for site development. It is recommended that PSI be retained to provide observation and testing of construction activities involved in the foundation, earthwork, and related activities of this project. These tests and inspections should include, but not necessarily limited to, the following: • . Full-time observation and testing by the geotechnical consultant of record during site clearing, grading, excavation, placement of fills,. and backfilling of utility trenches. Critical observations and testing should be made during benching, removal depths, and fill density testing; • Inspection of foundation excavations, footings, and reinforcing steel before concrete placement; • Consultation as may be required during construction. In addition, the project plans and specifications should be reviewed by us to verify compatibility with our recommendations and conclusions. Additional information concerning the scope and cost of these services can be obtained from our office. REPORT LIMITATIONS The recommendations submitted are based on the available subsurface information obtained by PSI and the design concept you provided for the proposed project. If there are any revisions to the plans for this project or if deviations from the subsurface conditions noted in this or any supplemental report prepared by PSI are encountered during construction, PSI requires we be notified immediately to determine if changes in our recommendations are required. If PSI is _not retained to perform these functions, PSI will not be responsible for the impact of those conditions on the project. Proposed Retail/Commercial Development, La Quinta, CA IProfessional Service Industries, Inc. The conclusions and recommendations in this report are based on current information regarding the proposed construction. The conclusions and recommendations provided may be invalid if: • The structural loads change from those stated or the structures are relocated; • The Additional Services section of this report is not followed; This report is used for adjacent or other property; • Changes of grade or groundwater occur between the issuance of this report and construction other than those anticipated in this report; • Any other change is implemented, which materially alters the project from that proposed at the time this report was prepared. PSI warrants that the findings, recommendations, specifications, or professional advice contained herein have been made in accordance with generally accepted professional geotechnical engineering practices in the local area. No other warranties are implied or expressed. After the plans and specifications are more complete, PSI should be retained and provided the opportunity to review the_ final -design jPlans,and zspecifcatioc►s to.checktithat our engineering recommendations_ have been -properly i nrporated_into the=design documents. o _qe °MPSI did not provide any service to investigate or detect the presence of moisture, mold, or other biological contaminants in or around any structure, or any service that was designed or intended to prevent or lower the risk of the occurrence of the amplification of the same. Mold is ubiquitous to the environment with mold amplification occurring when building materials are impacted by moisture. Site conditions are outside of PSI's control, and mold amplification will likely occur, or continue to occur, in the presence of moisture. As such, PSI cannot be held responsible for the occurrence or recurrence of mold amplification. This report has been prepared for the exclusive use of Newmark for the specific application to the proposed retail/commercial development at the northeast corner of Highway 111 and Dune Palms Road, in the City of La Quinta, California. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. FIGURES Proposed Retail/Commercial Development, La Quinta, CA y Professional Service Industries, Inc. y ' 17"N : ♦�4. gv ^! t S �° �% �'.�,, �nca \t ` 9M 3 lt+, a : r t.WMI, 121 s`� ma 121 } \ ' ,\ `� •., _-� �\ 'I �; t f'' \��,� ` , 1,, It ♦ .) I f? t • ....... ars . A/ • "'� . kev.."'i` B��Y� g� r �Y'/...`a.L ! " _. i' d, )" r e ,� ''^i;1,�. 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Ir.. `n , _ -` •,,k >L%r:.:i:i. •.> » titb RMF I13{Ilb wa • > •Ir"" : i� ' Lriiiiv p ,.� J 1 �J'Q , 1 r .,•lu �� i •e t t.': t .. t' k —� � G ••ear ..aa 1_._ w Water r i se .I - } - .L. f \ ` : ♦ ai a< - e er "^ . :'moi >�� !.• , 397%'• ♦ Reiy» `\ y w �si Hew a AVENU •50 A _.• 'l ; _ ( ♦ (� din ♦Y ♦ O. .a �:% •AS -. ) " ' ~ V. Q :$ ! i 1 •.J�? ai 1`. ..!_ � �`u� W _ a ♦ m>% I !e t- 'h 'a >%x� ♦♦ at . q - - -. o n. �j I 7 .2 S :7� �ie�B♦ i' a a i" rt a •n fes+• Br bis « ece•. ax . £ • riwa eP i a Ja s •! ' �. - � °"a8'-��.i� a'1 It s <:.......� ........... -yLa :� `^.i . ♦♦ • edt � .,��n:i '., �'U� �ViY'��ils: a c O; ..6 � \,,,, ♦ •.. i • e� s sx h� t « r, ♦♦ a h! � !, r. ®: .. jai . ; a ..��::. is Y .ter °> �at�tt 9�#t re •,x. - t eri %e�: iiir. B�arYy «, ��. � � �,. Re . .2 ,l i• 4 »'S"� ' >n:`eea 3D T9.Q—b Cg)d& 07999 Ddmoe Yam�gJlE 9M6 SameElabLUSGS T90ft,S,,kj:8,000 DbbD: 139: D�:WGW4 Environmental PROJECT NAME: SITE VICINITY MAP �E GeotechnicalFigure rjf 1 Censtructie n Consulting • Engineering • Testing 3960 Gilman Street PROPOSED RETAIUCOMMERCIAL DEVELOPMENT NEC of Highway 111 & Dune Palms Map: La Quints, California N Long Beach, CA 90815 Quadrangle 562/597-3977 Rd Fax 562/597-8459' La Quinta, California 7,5' USGS Topographic Map PROJECT NO. 073-55001 Ate; Environmental PROJECT NAME: �E Geotechnical Construction Consulting a Engineering a Testing PROPOSED RETAIUCOMMERCIAL 3960 Gilman Street DEVELOPMENT Long Beach, CA 90815 NEC of Highway 111 & Dune Palms Rd 562/597-3977 La Quinta, Califomia Fax 562/597-8459 PROJECT NO. 073-55001 BORING Approximate LOCATION MAP Boring Location Figure 2 N APPENDIX A REFERENCES Proposed Retail/Commercial Development; La Quinta, CA Professional Service Industries, Inc. REFERENCES 1. Blake, T.F., 1995, Documentation for Eqfault Version 2.01 Update, Thomas F. Blake Computer Services and Software, Newbury Park, California, p. 79 and appendices. 2. Blake, T. F., 1998, New Fault -Model Files For FRISKSP and EQFAULT, Thomas F. Blake Computer Services and Software, Newbury Park, California. 3. California Division of Mines and Geology, 1998, Seismic Hazard Official Map, La Quinta Quadrangle, Scale: 1:24,000. .4.. Campbell, K.W. and Bozorgnia, Y., 1994, Near -Surface Attenuation of Peak Horizontal Acceleration From Worldwide Accelerograms Recorded From 1957 to 1993, Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Vol III, Earthquake Engineering Research Institute, pp. 283-292. 5. Hart, E.W. and Bryant, W.A., 1994, Fault -rupture Hazard Zones in California, ,California Division of Mines and Geology Special Publication 42. 6. Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, scale 1:750,000, California Division of Mines and Geology. 7. Jennings, C.W. and Strand, R.G. 1969, Olaf P. Jenkins Edition, Geologic Map of California, Los Angeles Sheet, California Division of Mines and Geology, Scale: 1:250,000. 8. US Geological Survey, La Quinta Quadrangle, California. United States Department of the Interior, Scale: 1:24,000, 1999. Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. APPENDIX B EXPLORATION LOGS Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. APPENDIX C LABORATORY TEST RESULTS Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. LABORATORY TEST RESULTS Laboratory Testing Program Laboratory tests were performed on representative soil samples to determine their relative engineering properties. Tests were performed in general accordance with test methods of the American Society for Testing Materials or other accepted standards. The following presents a brief description of the various test methods used. . Classification - Soils were classified 'visually according to the Unified Soil Classification System. Visual classifications were supplemented by laboratory testing of selected samples in general accordance with ASTM D2487. The soil classifications are shown on the Exploration Logs, Appendix B. In -Situ Moisture/Density - The in-place moisture content and dry unit weight of selected samples were determined using relatively undisturbed samples from the linear rings of a 2.38 inch I.D. modified California Sampler. The dry unit weight and moisture content are shown on the Exploration Logs, Appendix B. Direct Shear Tests - Consolidated, drained, direct shear tests were performed on undisturbed samples in general accordance with ASTM D-3080. The undisturbed samples were tested in a saturated condition using normal loads of 1 ksf, 2 ksf, and 4 ksf. Soluble Sulfate - In order to estimate the concrete degradation potential of soils, the content of soluble sulfates was determined in general accordance with Cal Test Method 417A. Soils with a sulfate concentration greater than 0.07% may be corrosive to -metals; concentrations greater than 0.10% are considered potentially- harmful to concrete and would require following the current Uniform Building Code for "moderate" or "severe" sulfate exposure requirements. a Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. SUMMARY OF LABORATORY TEST RESULTS RESULTS OF DIRECT SHEAR TEST (ASTM D 3080) SAMPLE LOCATION COHESION PHI ANGLE 4 B5 @ 5 ft. r 31 psf 28 degrees 137 @ 5 ft. 0 psf 35 degrees RESULTS OF SULFATE TEST (CAL 417A) SAMPLE LOCATION SOLUBLE SULFATE 0.174% by weight B1 @ 0 - 5 ft. (Degree of Attack - Moderate) t Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. Direct'Shear -Test Data Plot S.00 4.50 4.00 3.50 en 3.00 2.50 2.00 1.50 1.00 0.50 0:00 • Test Data Curve Fit 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Normal Stress (ksli) DIRECT SHEAR TEST REGRESSION ANALYSIS CURVE FIT BY LEAST SQUARES METHOD PROJECT: Proposed Retail/Commercial Development BORING NO.: B5 PROJECT NO.: 056-55001 DEPTH: 5Ft DATE: 1/31/2005 SAMPLE TYPE: Undisturbed DATA POINTS RESULTS X (ksf) Y (ksf) 0.60' 0.34 Angle phi = 28 degrees D 1.05 0.61 Cohesion = 31 lb/sq ft Direct'Shear -Test Data Plot S.00 4.50 4.00 3.50 en 3.00 2.50 2.00 1.50 1.00 0.50 0:00 • Test Data Curve Fit 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Normal Stress (ksli) r r 1.70 1.18 Direct Shear Test Data Plot S.00 4.00 C 3.00 sa • Test Data 2.00 — Curve Fit 1.00 to 0.00,- 0. .00.0. 0 '' .1. 0 2. 0 3. 0 4. 0 5.00 6.)0 -1.00 Normal Stress (ksi) �t+i Inforrzation BidId On' t• 'Coneuldm1> • :'fesdng DIRECT SHEAR TEST REGRESSION ANALYSIS CURVE FIT BY LEAST SQUARES METHOD PROJECT: Proposed Retail/Commercial Development BORING NO.: B7 PROJECT NO.: 056-55001 DEPTH: 5Ft DATE: 1/31/2005 SAMPLE TYPE: Undisturbed DATA POINTS RESULTS X (kst) Y (kst) 0.60 0.41 Angle phi = 35 degrees 1.05 0.75 Cohesion = 0 lb/sq ft 1.70 1.18 Direct Shear Test Data Plot S.00 4.00 C 3.00 sa • Test Data 2.00 — Curve Fit 1.00 to 0.00,- 0. .00.0. 0 '' .1. 0 2. 0 3. 0 4. 0 5.00 6.)0 -1.00 Normal Stress (ksi) �t+i Inforrzation BidId On' t• 'Coneuldm1> • :'fesdng APPENDIX D SEISMIC ANALYSIS;. COMPUTER OUTPUT Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. CALIFORNIA FAULT MAP Dunes Business Park 1100 1000 900-- 800--. 00800 . 700-- 600-- 500,-- 400-- 7 00600500,400 300 • 200 100 +'dam SITE 0 -100 -400 -300 -200 -100 0 100 200 300 400 500 600 DESIGN RESPONSE SPECTRUM Seismic Zone: 0.4 Soil Profile: SD 2.50 2.25 M 0.25 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Period Seconds 2.00 1.75 0 Cz 1.50 OD 1.25 U Q 1.00 Cz 0.75 U a 0.50 M 0.25 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Period Seconds r r . MAXIMUM EARTHQUAKES Dunes Business Park E0 .001 .1 1 10 100 Distance (mi) C .1 ct a� 5 U .0 E0 .001 .1 1 10 100 Distance (mi) EARTHQUAKE MAGNITUDES & DISTANCES . Dunes Business Park 7.75. 7.50 7.25 a� 7.00 cz 6.75 6.50 .1 1 10 100 Distance (mi) -o 0 Acceleration (g) o DIP -SLIP FAULTS 14) Campbell & Bozorgnia (1997 Rev.) - Alluvium M=5 M=6 M=7 M=8 1' .001 1 10 100 Distance [adist] (km) STRIKE -SLIP FAULTS 14) Campbell & Bozorgnia (1997 Rev.) - Alluvium M=5 M=6 M=7 M=8 04 Ro E0 .1 .01 '.001 1 10 100 Distance [adist] (km) APPENDIX E STANDARD GUIDELINES FOR GRADING PROJECTS Proposed Retail/Commercial Development, La Quinta, CA Professional Service Industries, Inc. Standard Guidelines For Grading Projects STANDARD GUIDELINES FOR GRADING PROJECTS Presented By: Professional Service Industries, Inc. Standard Guidelines For Grading Projects TABLE OF CONTENT GENERAL......... ».......... »......... ».......... »..... ».......... »......... ».......... ».......... »......... ............................... SG -1 DEFINITIONOF TERMS.........»..........».........».................»..........».........»..........»............................».. 1 OBLIGATIONSOF PARTIES ............................... ....................................................... ........... ......... 5 SITEPREPARATION ......... ».......... ».......... ».......... ».......... ».......... ».......... »............................................ 5 SITEPROTECTION.....................».........»..........».................».........»..........».......................................... 6 EXCAVATIONS.........»..........»..........»..........»..........».....:................»..........»..........»............................. 7 Unsuitable Materials.........»..........».........»..........».................».........»..........»...................................... 7 Cut Slopes ............................... ............ ................. ...................... :.......... ......... ................. ........... ...... 7 PadAreas.........»...........:..........»......................»..........»..........»..........»..........»..............................»..... 8 COMPACTEDFILL ...... ................................................................................................................... 8 Placement...................».........»..........».................».........»..........»..........».........»............................».... 8 { Moisture.....................».........»..........»........... .................»..........»..........».........»..................»...............10 FillMaterial.........».....................»..........»..........»......................»..........»..........»................»..............10 FillSlopes.........»..........»........:.»......................»..........»..........»..........»..........»............................».....12 Off -Site Fill ......... ............ »......... ».......... »..... »........... _......... ».......... ».......... »......... » ............. ........... ».... 13 DRAINAGE................................ ............................... .».......... » ......................».....»...............».............13 STAKING.........»..........»......................»...........:......................»..........»..........».....»................»...............14 SLOPEMAINTENANCE ......... ............ ........... ».......... »................. »......... ».......... ».......... ........... ».......... 14 Landscape Plants ......... ».......... »......... ».......... ».:............... »......... ».......... ».......... »......... ........... »......... 14 • Irrigation.........»..........».........»..........».....»..........».........»..........»..........».........»..........................»....14 Maintenance ......... ».......... ».......... ».......... »..... ».......... »......... ».......... ........... »......... . ...............»............15 Repairs ......................................................................................................................................... 15 TRENCHBACKFILL .............................. ....................................................................... ............»...15 STATUSOF GRADING ......... ».......... ».......... ».......... ».................».........»..........»...............................»..16 Standard Guidelines For Grading Projects GENERAL The guidelines contained herein and the standard details attached hereto represent this firm's standard recommendation for grading and other associated operations. on construction projects. These guidelines should be considered a portion of the project specifications. All plates attached hereto shall be considered as part of these guidelines. The Contractor should not vary' from these guidelines without prior recommendation by the Geotechnical Consultant and the approval of the Client or his authorized representative. Recommendation by the Geotechnical Consultant and/or Client should not be considered to preclude requirements for the approval by the controlling agency prior to the execution of any changes. These Standard Grading Guidelines and Standard Details may be modified and/or superseded by recommendations contained in the text of the preliminary Geotechnical Report and/or subsequentreports. If disputes arise out of the interpretation of these grading guidelines or standard details, the Geotechnical Consultant shall provide the governing interpretation. DEFINITION OF TERMS . ALLUVIUM — Unconsolidated soil deposits resulting from flow of water, including sediments deposited in river beds, canyons, flood plains, lakes, fans and estuaries. AS -GRADED (AS -BUILT) — The surface and subsurface conditions 'at completion of grading. BACKCUT = A temporary construction slope at the rear of earth retaining structures such as buttresses, shear keys, stabilization fills or retaining walls. BACKDRAIN — Generally a pipe and gravel or similar drainage system placed behind earth retaining structures such buttresses, stabilization fills, and retaining walls. BEDROCK — Relatively undisturbed formational rock, more or less solid, either at the surface or beneath superficial deposits of soil. - BENCH — A relatively level step and near vertical rise excavated into sloping ground on which fill is to be placed. areas. BORROW (Import) — Any fill material' hauled to the project site from off-site SG - 1 Standard Guidelines For Grading Projects BUTTRESS FILL — A fill mass, the configuration of which is designed by engineering calculations to retain slope conditions containing adverse geologic features. A buttress is generally specified by minimum key width and depth and by maximum backcut angle. A buttress normally contains a back -drainage system. CIVIL ENGINEER — The Registered Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as -graded topographic conditions. CLIENT —1 The Developer or his authorized representative who is chiefly in charge of the project. He shall have the responsibility of reviewing the findings and recommendations made by. the Geotechnical Consultant and shall authorize the Contractor and/or other consultants to perform work and/or provide services. COLLUVIUM — Generally loose deposits usually found near the base of slopes and brought there chiefly by gravity through slow continuous downhill creep (also see Slope Wash). COMPACTION — Densification of man -placed fill by mechanical means. CONTRACTOR — A person or company under contract or otherwise retained by the Client to perform demolition, grading and other site improvements. DEBRIS — All products of clearing, grubbing, demolition, and contaminated soil materials unsuitable for reuse as compacted fill, and/or any other material so designated by the Geotechnical Consultant. ENGINEERING GEOLOGIST — A Geologist holding a valid certificate of registration in the specialty of Engineering Geology. ENGINEERED FILL — A fill of which the Geotechnical Consultant or his representative, during grading, has made sufficient tests to enable him to conclude that the fill has been placed in substantial compliance with the recommendations of the Geotechnical Consultant and the governing agency requirements. EROSION - The wearing away of ground surface as a result of the movement of wind,. water, and/or ice. EXCAVATION — The mechanical removal of earth materials. EXISTING GRADE — The ground surface configuration prior to grading. FILL — Any deposits of soil, rock, soil -rock blends or other similar materials placed by man. SG -2 Standard Guidelines For Grading Projects FINISH GRADE — The ground surface configuration at which time the surface elevations conform to the approved plan. GEOFABRIC — Any engineering textile utilized in geotechnical applications including subgrade stabilization and filtering. -GEOLOGIST — A representative of the Geotechnical Consultant educated and trained in the field of geology. GEOTECHNICAL CONSULTANT — The Geotechnical Engineering and Engineering Geology consulting firm retained to provide technical services for the project. For the purpose of these specifications, observations by the Geotechnical Consultant include observations -by the Soil Engineer, Geotechnical Engineer, Engineering Geologist and those performed by persons employed by and responsible to. the Geotechnical Consultants. GEOTECHNICAL ENGINEER — A licensed Geotechnical Engineer or Civil Engineer who applies scientific methods, engineering principles and professional experience to the acquisition, interpretation and use of knowledge of materials of the earth's crust for the evaluation of engineering problems. Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics, rock mechanics, geology, geophysics, hydrology and related sciences. GRADING — Any operation consisting of excavation, filling or combinations thereof and associated operations. LANDSIDE DEBRIS — Material, generally porous and of low density, produced from instability of natural or man-made slopes. MAXIMUM DENSITY — Standard laboratory test for maximum dry unit weight. Unless otherwise specified, the maximum dry unity weight shall be determined in accordance with ASTM Method of Test D 1557-91. OPTIMUM MOISTURE — Soil moisture content at the test maximum density. RELATIVE COMPACTION — The degree of compaction (expressed as a percentage) of dry unit weight of a material as compared to the maximum dry unit weight of the material. ROUGH GRADE — The ground surface configuration at which time the surface elevations approximately conform to the approved plan. .SITE - The particular parcel of land where grading is being performed. SG -3 Standard Guidelines For Grading Projects SHEAR KEY — Similar to buttress, however, it is generally constructed by excavating a slot within a natural slope, in order to stabilize the upper portion of the slope' without grading encroaching into the lower portion of the slope. SLOPE An inclined ground surface, the steepness of. which is generally specified as a ration of horizontal:vertical (e.g., 2:1) SLOPE WASH — Soil and/or rock material that has been transported down a slope by action of gravity assisted by runoff water not confined by channels (also see Colluvium). . SOIL. — Naturally occurring deposits of sand, silt, clay, etc., or combinations thereof. - . • SOIL ENGINEER — Licensed .Geotechnical Engineer or Civil Engineer experienced in soil mechanics (also see Geotechnical Engineer). STABILIZATION FILL — A fill mass, the configuration of which is typically related to slope height and specified by the standards of practice for enhancing. the stability of locally adverse conditions. . A stabilization fill isnormally specified by minimum key width and depth and by maximum backcut angle. A stabilization fill may or may not have a backdramage system specified. SUBDRAIN — Generally a pipe and gravel or similar drainage system placed beneath a fill in the alignment of canyons or formed drainage channels. SLOUGH — Loose, non -compacted fill material generated during grading operations. - TAILINGS — Non -engineered fill which accumulates on or adjacent to equipment haul -roads. . TERRACE — Relatively level step constructed in the face of a graded slope surface for drainage control and maintenance purposes. TOPSOIL - The presumable fertile upper zone of soil, which is usually darker in color and loose. WINDROW — A string of large rocks buried within engineered fill in accordance with guidelines set forth by the Geotechnical Consultant. t ' SG -4 Standard Guidelines For Grading Projects OBLIGATIONS OF PARTIES The Geotechnical Consultant should provide observation and testing services and should make evaluations in order to advise the Client on Geotechnical matters. The Geotechnical Consultant should report his findings and recommendations to the Client or his. authorized representative. The client should be chiefly responsible for all aspects of the project. He or his authorized representative has the responsibility of reviewing the findings and recommendations of the Geotechnical Consultant. He shall authorize or cause to have authorized the Contractor and/or other consultants to perform work and/or provide services.' During grading the Client or his authorized representative should remain on- site or should remain reasonably accessible to all concerned parties in order to. make decisions necessary to maintain the flow of the project. The Contractor should be responsible for the safety of the project and satisfactory completion of all grading and other associated operations on construction projects, including but not limited to, earthwork in accordance with the project plans, specifications and controlling agency requirements. During grading, the Contractor or his authorized representative should remain on-site. Overnight and on days off, the Contractor should remain accessible. SITE PREPARATION The Client, prior to any site preparation or grading, should arrange and attend a meeting among the Grading Contractor, the Design Engineer, the Geotechnical Consultant, representatives of the appropriate governing authorities as well as any other concerned parties. All parties should be given at least 48 hours notice. Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, roots of trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas. Demolition should include removal of buildings, structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, tunnels, etc.) and man-made surface and subsurface improvements from the areas to be graded. Demolition of utilities should include proper capping and/or re-routing pipelines at the project perimeter and cutoff and capping of wells in accordance with the requirements of the governing authorities and the recommendations of the Geotechnical Consultant at the time of the demolition. Trees, plants or man-made improvements not planned to be removed or demolished should be protected by.the Contractor from damage or injury. SG -5 Standard Guidelines For Grading Projects Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed off-site. Clearing, grubbing and demolition operations should be performed under the observation of the Geotechnical Consultant. The Client or Contractor should obtain the required approvals for the controlling authorities for the project prior, during and/or after demolition, site preparation and removals, etc. The appropriate approvals should be obtained prior to proceeding with grading operations. SITE PROTECTION Protection of the site during the period of grading should be the responsibility of the Contractor. Unless other provisions are made in writing and agreed upon among the concerned parties, completion of a portion of the project should not be considered to preclude that portion or adjacent areas from the requirements for site protection until such time as the entire project is complete as identified by the Geotechnical Consultant, the Client and the regulating agencies. The Contractor should be responsible for the stability of all temporary excavations. Recommendations by the Geotechnical Consultant pertaining to temporary excavations (e.g., backcuts) are made in consideration of stability of the completed project and therefore, should not be considered to preclude the responsibilities of the Contractor. Recommendations by the Geotechnical Consultant should not be considered to preclude more restrictive requirements by the regulating agencies. Precautions should be taken during the performance of site clearing, excavations and grading to protect the work site from flooding, ponding, or inundation by poor or improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site. Where low areas can not be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. During periods of rainfall, plastic sheeting should be kept reasonably accessible to prevent unprotected slopes from becoming saturated. Where necessary during periods of rainfall, the Contractor should install check -dams de -silting basins, rip -rap, sandbags or other devices or methods necessary to control erosion and provide safe conditions. During periods of rainfall, the Geotechnical Consultant should be kept informed by the Contractor as to the nature of remedial or preventative work being performed (e.g., pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.). Following periods of rainfall, the Contractor should contact the Geotechnical Consultant and arrange a walk -over of the site in order to visually assess rain related damage. The Geotechnical Consultant may also recommend excavations and testing in order to aid in his assessments. At the request of the Geotechnical Consultant, the Contractor shall make excavations in order to evaluate the extent of rain related damage. SG -6 Standard Guidelines For Grading Projects Rain -related damage should be considered to include, but may not be limited to, erosion, silting, saturation, swelling, structural distress and other adverse conditions identified by the Geotechnical Consultant. Soil adversely affected should be classified as Unsuitable Materials and should be subject to overexcavation and replaced with compacted fill or other remedial grading as recommended by the Geotechnical Consultant. Relatively level areas, where saturated soils and/or erosion gullies exist to depths greater. then 1 foot, should be overexcavated to unaffected, competent material. Where less than 1 foot in depth, unsuitable materials may be processed in-place to achieve near optimum moisture conditions, then thoroughly recompacted in accordance with the applicable specifications. If the desired results are not achieved, the affected materials should be overexcavated then replaced in accordance with the applicable specifications. In slope areas, where saturated soil and/or erosion gullies exist to depths of greater than 1 foot, should be over -excavated to unaffected, competent material. Where affected materials exist to depths of 1 foot or less below proposed finished grade, remedial grading by moisture conditioning in-place, followed by thorough recompaction in accordance with the applicable grading guidelines herein may be attempted. If the desired results are not achieved, all affected materials should be overexcavated and replaced as compacted fill in accordance with the slope repair recommendations herein. As field conditions dictate, other slope repair procedures may be recommended by the Geotechnical Consultant. EXCAVATIONS Unsuitable Materials Materials which are unsuitable should be excavated under observation and recommendations of the Geotechnical Consultant. Unsuitable materials include, but may not be limited to dry, loose, soft, wet, organic compressible natural soils and fractured, weathered, soft, bedrock and nonengineered'or otherwise deleterious fill materials. Materials identified by the Geotechnical Consultant as unsatisfactory due to its moisture conditions should be overexcavated, watered or dried, as needed, and thoroughly blended to uniform near optimum moisture condition (per Moisture guidelines presented herein) prior to placement as compacted fill. Cut Slopes Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent cut slopes should not be steeper than 2:1 (horizontal:vertical). If excavations for cut slopes expose loose, cohesionless, significantly fractured or otherwise suitable material, overexcavation and replacement of the unsuitable materials SG -7 Standard Guidelines For Grading Projects with a compacted stabilization fill should be accomplished as recommended by the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant, stabilization fill construction should conform to the requirements of the Standard Details. The Geotechnical Consultant should review cut slopes during excavation. The Geotechnical Consultant should be notified by the contractor prior to beginning slope excavations. If during the course of grading, . adverse or potentially adverse geotechnical conditions are encountered which were not anticipated in the preliminary report, the Geotechnical Consultant should explore, analyze and make recommendations to treat these problems. When cuts slopes are made in the direction of the prevailing drainage, a non - erodible diversion Swale (brow ditch) should be provided at the top -of -cut. Pad Areas All lot pad areas, including side yard terraces, above stabilization fills or buttresses should be over -excavated to provide for a minimum of 3 -feet (refer to Standard Details) of compacted fill over the entire pad area. Pad areas with both fill and cut materials exposed and pad areas containing both very shallow (less than 3 -feet) and deeper fill should be over- thickness (refer to Standard Details). Cut areas exposing significantly varying material types should also be overexcavated to provide for at least a 3-f6ot thick compacted fill blanket. Geotechnical conditions may require greater depth of overexcavation. The actual depth should be delineated by the Geotechnical Consultant during grading. For pad areas created above cut or natural slopes, positive drainage should be established away from the. top -of -slope. This may be accomplished utilizing a berm and/or an appropriate pad gradient. A gradient in soil areas away from the top -of -slope of 2 percent or greater is recommended. COMPACTED FILL - All fill materials should be compacted as specified below or by other methods specifically recommended by the Geotechnical Consultant. Unless otherwise specified, the minimum degree of compaction (relative compaction) should be 90 percent of the .laboratory maximum density. Placement ` Prior to placement of compacted fill, the Contractor should request a review by the Geotechnical Consultant of the exposed ground surface. Unless otherwise recommended, the exposed ground surface should then be scarified (6 -inches minimum), watered or dried as needed, thoroughly blended to achieve near optimum moisture SG -8 Standard Guidelines For Grading Projects conditions, then thoroughly compacted to a minimum of 90 percent of the maximum density. The review by the Geotechnical Consultants should not be considered to preclude requirements of inspection and approval by the governing'agency. Compacted fill should be placed in thin horizontal lifts not exceeding 8 -inches in loose thickness prior to compaction. Each lift should be watered or dried as needed, thoroughly blended to achieve near optimum moisture conditions then thoroughly compacted by mechanical methods to a minimum of 90 percent of laboratory maximum dry density. Each lift should be treated in a like manner until the desired finished grades are achieved. The Contractor should have suitable and sufficient mechanical compaction equipment and watering apparatus on the job site to handle the amount of fill being placed in consideration—of moisture retention properties of the materials. If necessary, excavation equipment should be "shut. down" temporarily in order to permit proper compaction of fills. Earth moving equipment should only be considered a supplement and not substituted for conventional compaction equipment. When placing fill in horizontal lifts adjacent to areas sloping steeper than'5:1 (horizontal:vertical), horizontal keys and vertical benches should be excavated into the adjacent slope area. Keying and benching should be sufficient to provide at least 6 -foot wide benches and minimum of 4 -feet of vertical bench height within the firm natural ground, firm bedrock or engineered compacted fill. No compacted fill should be placed in an area subsequent to keying and benching until the area has been reviewed by the Geotechnical Consultant. Material generated by the benching operation should be moved sufficiently away from the bench area to allow for the recommended review of the horizontal bench prior to placement of fill. Typical keying and benching details have been included within the accompanying Standard Details. Within a single fill area where grading procedures dictate two or more separate fills, temporary slopes (false slopes) may be created: When placing fill adjacent to a false slope, benching should be conducted in the same manner as above described. At least a 3 -foot vertical bench should be established within the firm core of adjacent approved compacted fill prior to placement of additional fill. Benching should proceed in at least 3 -foot vertical increments until the desired finished grades are achieved. Fill should be tested for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to ASTM Method of Testing D 1556-64, D 2922-78 and/or D2937-71. Tests should be provided for about every 2 vertical feet or 1,000 cubic yards of fill placed. Actual test intervals may vary as field conditions dictate. Fill found not to be in conformance with the grading recommendations should be removed or otherwise handled as recommended by the Geotechnical Consultant. SG -9 Standard Guidelines For Grading Projects The Contractor should assist the Geotechnical Consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill. As recommended by the Geotechnical Consultant, the Contractor should "shutdown" or remove any grading equipment from an area being tested. The Geotechnical Consultant should maintain a plan with estimated locations of field tests. Unless the client provides for actual surveying of test locations, by the Geotechnical Consultant should only be considered rough estimates and should not be utilized for the purpose of preparing cross sections showing test locations or in any case for the purpose of after -the -fact evaluating of the sequence of fill placement. Moisture _ For field testing purposes, "near optimum" moisture will vary with material type and other factors including compaction procedures. "Near optimum" may be specifically recommended in Preliminary Investigation Reports . and/or may be evaluated during grading. Prior to placement of additional compacted fill following an overnight or other grading delay, the exposed surface of previously compacted fill should be processed by scarification, watered or dried as needed, thoroughly blended to near -optimum moisture conditions, then recompacted to a minimum of 90 percent of laboratory maximum dry density. Where wet or other dry or other unsuitable materials exist to depths of greater than one foot, the unsuitable materials should be overexcavated. Following a period of flooding, rainfall or overwatering by other means, no additional fill should be placed until damage assessments have been made and remedial grading performed as described herein. Fill Material _.... Excavated on-site materials which are acceptable to the Geotechnical Consultant may be utilized as compacted fill, provided trash, vegetation and other deleterious materials are removed prior to placement. Where import materials are required for use on the Geotechnical Consultant should be notified at least 72 hours in advance of importing, in order to sample and test materials from proposed borrow sites. No import materials should be delivered for use on-site without prior sampling and testing by Geotechnical Consultant. Where oversized rock or similar irreducible material is generated during grading, it is recommended, where practical, to waste such material off-site or on-site in areas designated as "nonstructural rock disposal areas". Rock placed in disposal areas should be placed with sufficient fines to fill voids. The rock should be compacted in lifts to an SG- 10 Standard Guidelines For Grading Projects unyielding condition. The disposal area should be covered with at least 3 -feet of compacted fill, which is free of oversized material. The upper 3 -feet should be placed in accordance with the guidelines for compacted fill herein. Rocks 12 inches in maximum dimension and smaller 'may 'be utilized within the compacted fill, provided they are placed in such a manner that nesting of the rock in avoided. Fill should be placed and thoroughly compacted over and around all rock. The amount of rock should not exceed 40 percent by dry weight passing the 3/e-inch.sieve size. The 12 -inch and 40 percent recommendations herein may vary as field conditions dictate. During the course of grading operations, rocks or ' similar irreducible materials greater than 12 -inch maximum dimension (oversized material) may be generated. These rocks should not be placed within the compacted fill unless placed as recommended by the Geotechnical Consultant. Where rocks or similar irreducible materials of greater that 12 -inches but less than 4 -feet of maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the accompanying Standard Details is recommended. Rocks greater than 4 feet should be broken down or disposed off -sire. Rocks up to 4 -feet maximum dimension should be placed below the upper 10 -feet of any fill and should not be closer than 20 -feet to any slope face. These recommendations could vary as locations of improvements dictate. Where practical, oversized material should not be placed below areas where structures of deep utilities are proposes. Oversized material should be placed in windrows on a clean, overexcavated or unyielding compacted fill or ' firm natural ground surface. Select native or imported granular soil (S.E. 30 or higher) should be placed and thoroughly flooded over and around all windrowed rock, such that voids are filled. Windrows of oversized material should be staggered so that successive strata of oversized material are not in the same vertical plane. It may be possible to dispose -of individual larger rock as field conditions dictate and as recommended by the Geotechnical Consultant at time of placement. Material that is considered unsuitable by the Geotechnical Consultant should not be utilized in the compacted fill. -During grading operations, placing and mixing the materials from the cut and/or borrow areas may result in soil mixtures which possess unique physical properties. Testing may be required of samples obtained directly from the fill areas in order to verify conformance with the specifications. Processing of these additional samples may take two or more working days. The Contractor may elect to move the operation to other areas within the project, or may continue placing compacted fill pending laboratory and field test results. Should he elect the second alternative, fill placed is done so at the Contractor's risk. SG -11 Standard Guidelines For Grading Projects Any fill placed in areas not previously reviewed and evaluated by the Geotechnical Consultant, and/or in other areas, without prior notification to the Geotechnical Consultant may require removal and recompaction at the Contractor's expense. Determination of overexcavations should be made upon review of field conditions by the Geotechnical Consultant. Fill Slopes U Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, permanent fill slopes should not be steeper than 2:1 (horizontal to vertical). Except as specifically recommended otherwise or as otherwise provided for in these grading guidelines (Reference Fill Materials), compacted fill slopes should be overbuilt and cut back to grade, exposing the firm, compacted fill inner core. The actual amount of overbuilding may vary as field conditions dictate. If the desired results are not achieved, the existing slopes should be overexcavated and reconstructed under the guidelines of the Geotechnical' Consultant. The degree of overbuilding shall be increased until the desired compacted slope surface condition is achieved. Care should be taken by the Contractor to provide thorough mechanical compaction to the outer edge of the overbuilt slope surface. Although no construction procedure produces a slope free from risk of future movement, overfilling and cutting back of slope to a compacted inner core is, given no other constraints, the most desirable procedure. Other constraints, however, must often be considered. These constraints may include property line situations, access, the critical nature of the development, and cost. Where such constraints are identified, slope face compaction may be attempted by conventional construction procedures including backrolling techniques upon specific recommendations by the Geotechnical Consultant. As a second best alternative for slopes of 2:1 (horizontal to vertical) or flatter, slope construction may be attempted as outlined herein. Fill placement should proceed in thin lifts, (i.e., 6 to 8 inch loose thickness). Each lift should be moisture conditioned and . thoroughly compacted. The desired moisture condition should be maintained and/or reestablished, where necessary, during the•period between successive lifts. Selected lifts should be tested to ascertain that desired compaction is being achieved. Care should be taken to extend compactive effort to the outer edge of the slope. Each lift should extend horizontally to the desired finished slope surface or more as needed to ultimately establish desired grades. Grade during construction should not be allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the outer edge of the slope. Slough resulting from the placement of individual lifts should not be allowed to drift down over previous lifts. At intervals not exceeding 4 -feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be thoroughly backrolled utilizing a conventional sheepsfoot-type roller. Care should be taken to maintain the desired moisture conditions and/or reestablishing same as needed prior to backrolling. Upon achieving final grade, the slopes should again be moisture conditioned SG - 12 Standard Guidelines For Grading Projects and thoroughly backrolled. The use of a side -boom roller will probably be necessary and vibratory methods are strongly recommended. Without delay, so as to avoid (if possible) further moisture conditioning, the slopes should then be grid -rolled to achieve a relatively smooth'surface and uniformly compact condition. In order to monitor slope construction procedures, moisture and density tests will be taken at regular intervals. Failure to achieve the desired results will likely result in a recommendation by the Geotechnical Consultant to overexcavate the slope surfaces followed by reconstruction of the slopes utilizing overfilling and cutting back procedures and/or further attempt at the conventional backrolling approach. Other recommendations may also be provided which would be commensurate with field conditions. Where placement of fill above a natural slope or above a cut slope is proposed, the fill slope configuration as presented in the accompanying standard Details should be . adopted. ' For pad areas above fill slopes, positive drainage should be established away from the top -of -slope. This may be accomplished utilizing a berm and pad gradients of at least 2 -percent in soil area. Off -Site Fill Off-site fill should be treated in the same manner as recommended in these specifications for site preparation, excavation, drains, compaction, etc. Off-site canyon fill should be placed in preparation for future additional fill, as shown in the accompanying Standard Details. Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for future relocation and connection. DRAINAGE Canyon sub -drain systems specified by the Geotechnical Consultant should be installed in accordance with the Standard Details. Typical sub -drains for compacted fill buttresses, slope stabilization or sidehill masses, should be. installed in accordance with the specifications of the accompanying Standard Details. Roof, pad and slope drainage should be directed away from slopes and areas of structures. to suitable disposal areas via non -erodible devices (i.e., gutters, downspouts, concrete swales). For drainage over soil areas immediately away from structures (i.e., within 4 - feet), a minimum of 4 percent gradient should be maintained. Pad drainage of at least 2 percent should be maintained over soil areas. Pad drainage may be reduced to at least 1 SG - 13 Standard Guidelines For Grading Projects percent for projects where no slopes exist, either natural or man-made, or greater than 10 - feet in height and where no slopes are planned, either natural or man-made, steeper than 2:1 (horizontal to vertical slope ratio). Drainage patterns established at the time of fine grading should be maintained throughout the life of the project. Property owners should be made aware that altering drainage patterns can be detrimental to slope stability and foundation performance. STAKING In all fill areas, the fill should be compacted prior to the placement of the stakes. This particularly is important on fill slopes. Slope stakes should not be placed until the slope- is thoroughly compacted (backrolled). If stakes must be placed prior to the completion of compaction 'procedures, it must be recognized that they will be .removed and/or demolished at such time as compaction procedures resume. In order to allow for remedial grading operations, which could include overexcavations or slope stabilization, appropriate staking offsets should be provided. For finished slope and stabilization backcut areas, we recommend at least 10 -feet setback from proposed toes and tops -of -cut. SLOPE MAINTENANCE Landscape Plants In order to enhance superficial slope stability, slope planting should be accomplished at the completion of grading. Slope planting should consist of deep - rooting vegetation requiring little watering. Plants native to the Southern California area . a and plants relative to native plants are generally desirable. Plants native to other semi - and and and- areas may also be appropriate. A Landscape Architect would be the best party to. consult regarding actual types of plants and planting configuration. Irrigation Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into slope faces. Slope irrigation should be minimized. If automatic timing devices are utilized on irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall. Though not a requirement, consideration should be give to the installation of near - surface moisture monitoring control devices. Such devices can aid in the maintenance of relatively uniform and reasonably constant moisture conditions. SG - 14 Standard Guidelines . For Grading Projects Property owners should be made aware that overwatering of slopes is detrimental to slope stability. Maintenance Periodic inspections of landscaped slope areas should be planned and appropriate measures- should be taken to control weeds and enhance growth of the landscape plants. Some areas may require occasional replanting and/or reseeding. Terrace drains and downdrains should be periodically inspected and maintained free of debris. Damage to drainage improvements should be repaired immediately. Property owners should be made aware that burrowing animals can be detrimental. to slope stability: -A preventative. program should be established to control burrowing. - animals. As a precautionary measure, plastic sheeting should be readily available, or kept on hand, to protect all slope areas from saturation by periods of heavy or prolonged rainfall. This measure is strongly recommended, beginning with the period of time prior to landscape planting. Repairs If slope failures occur, the Geotechnical Consultant should be contacted for a field review of site conditions and development of recommendations for evaluation and repair. If slope failure occurs as a result of exposure to periods of heavy rainfall, the failure areas and currently unaffected areas should be covered with plastic sheeting to protect against additional saturation. In the accompanying Standard Details, appropriate repair procedures are illustrated for superficial slope failures (i.e., occurring typically within the outer. L-fo.ot. to 3 feet of a slope face). TRENCH BACKFILL Utility trench backfill should; unless otherwise recommended, be compacted by mechanical means. Unless otherwise recommended, the degree of compaction should be a minimum of 90 percent of the laboratory maximum density. . As an alternative, granular material (sand equivalent greater than 30) may be thoroughly jetted in-place. Jetting should only be'considered to apply to trenches no greater than 2 -feet in width and 4 -feet in depth. Following jetting operations, trench backfill should be thoroughly mechanically compacted and/or wheel -rolled from the surface. SG -15 Standard Guidelines For Grading Projects Backfill of exterior and interior trenches extending below a 1:1 projection from the outer edge of .foundations should be mechanically compacted to a minimum of 90 percent of the laboratory maximum density. Within slab areas, but outside the influence of foundations, trenches up to 1 foot wide and 2 feet deep may be backfilled with sand and consolidated by jetting, flooding or by mechanical means. If on-site materials are utilized, they should be wheel -rolled, tamped or otherwise compacted to a firm condition. For minor interior trenches, density testing may be deleted or spot testing may be elected if deemed necessary, based on review of back ill operations during construction. . If utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, the Contractor may elect the utilization of light weight compaction equipment and/or shading of the conduit with clean, granular material; which should be thoroughly jetted in-place above the conduit, prior to initiating mechanical compaction procedures. Other methods of utility trench compaction may also be appropriate, upon review by the Geotechnical Consultant at the time of construction. In cases where clean granular materials are proposed for use in lieu of native materials or where flooding or jetting is proposed, the procedures should be considered subject to review by the Geotechnical Consultant. Clean Granular backfill and/or bedding are not recommended in slope areas unless provisions are made for a drainage system to mitigate the potential build-up of seepage forces. STATUS OF GR ADING Prior to proceeding with any grading operation, the Geotechnical Consultant should be notified at least two working days in advance in order to schedule the necessary observation and testing services. Prior to any significant expansion of cut back in the grading operation, the Geotechnical Consultant should be provided with adequate notice (i.e., two days) in order to make appropriate adjustments in observation and testing services. Following completion of grading operations and/or between phases of a grading operation, the Geotechnical Consultant should be provided with at least two working days notice in advance of commencement of additional grading operations. SG - 16 15 a-0" —15, N/N/MUN 4' DIAMETER PERF0RATED PIPE BACKOWN 4 DIAMETER NON -PERFORATED PIPE LATERAL DRAINz�/`� j//�/% BENCHING SLOPE PER PLAN H12 2.09' �/�/�\/�f • r- �j X.ox 5.09 /,\`�/�\%�\� � `G( .� ,� •.� PROVIDE 84CKDRAIN PER 94CKDR4IN " DETAIL. 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