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HomeMy WebLinkAboutCT 03-03; BRESSI RANCH AFFORDABLE HOUSING; AS-GRADED REPORT OF FINE GRADING; 2004-06-25AS-GRADED REPORT OF FINE GRADING, AFFORDABLE HOUSING SITE, CARLSBAD TRACT NO. CT 03-03 NORTHWEST PORTION OF PLANNING AREA PA-15, CARLSBAD, CALIFORNIA Prepared for: GREYSTONE HOMES 1525 Faraday Avenue, Suite 300 Carlsbad, California 92008 Project No. 971009-025 June 25, 2004 Leighton and Associates, Inc. A LEIGHTON GROUP COMPANY 4 I Leighton and Associates, Inc. A LEIGHTON GROUP COMPANY June 25, 2004 Project No. 971009-025 To: Greystone Homes I 1525 Faraday Avenue, Suite 300 Carlsbad, California 92008 I Attention: Mr. Keith Randhahn Subject: As-Graded Report of Fine Grading, Affordable Housing Site, Carlsbad Tract No. I CT 03-03, Northwest Portion of Planning Area PA-15, Bressi Ranch, Carlsbad, California I Introduction I In accordance with the request and authorization of representatives of Greystone Homes, we have performed geotechnical observation and testing services during the fine grading operations of the affordable housing site in Planning Area 15 (Carlsbad Tract No. CT 03-03), located within the I Bressi Ranch development in Carlsbad, California (Figure 1). Grading operations for the site were performed by G.F. Whillock Grading with observation and testing by Leighton and Associates, Inc. I (Leighton). This as-graded report of fine grading summarizes our geotechnical observations, geologic mapping, field and laboratory test results, and the geotechnical conditions encountered during the fine grading I operations of the affordable housing development within Planning Area PA-15. In addition, this report provides conclusions and recommendations relative to the proposed post grading and residential development of the site. As of this date, the fine-grading operations of the site are I essentially complete. Ll I I 1 3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425 858.292.8030 • Fax 858.292.0771 • www.leightongeo.com INNOVATION WAY METROPOUTAN STREET LKANll NORTH Project No. 971009-025 Not to scale SITE LOCATION MAP '/GeOI. Affordable Housing Buildings 1-10 Drafted By KAM/BJO lip CT 03-03, Planning Area PA-1 5 Date June 2004 Bressi RanchCarlsbad, California Leghton and Assocates. I nc, Figure No. 1 I 971009-025 Site Location and Project Description The affordable housing site of the Bressi Ranch project is located in the northwest corner of Planning Area PA-IS. The site is bounded by Gateway Road to the north, Town Garden Road to the south, Village Green Drive to the west, and the remainder of Planning Area PA-15 to the east. Mass grading of the site was performed between September 2003 and March 2004 (Leighton, 2004). The rough grading resulted in a generally southwest sloping sheet-graded pad. The mass graded pad elevation ranged from approximately 380 feet (msl) in the southwest portion of the site to 405 feet in the northeast portion. The proposed development of Planning Area PA-is consists of 10 multi-unit affordable housing buildings with attached garages, driveways, carports, parking areas, minor slopes and associated improvements. Fine grading of the site consisted of minor cuts and fills creating the building pads, driveways/parking areas, slopes and open space areas. It is anticipated that the buildings will be two-story residential structures that will be constructed with slab-on-grade post-tension foundations and wood-frame and stucco construction. Other site improvements will include retaining walls, underground utilities, concrete flatwork, and landscaping. Summary of Fine Grading Operations The fine grading operations for the affordable housing site in the northwest portion of Bressi Ranch Planning Area PA- i 5 were performed between May and June 2004. The grading operations were performed by G.F. Whillock Grading, while Leighton and Associates performed the geotechnical observation and testing services. Our field technician was on-site on a full-time basis while our field geologist and office personal were on-site on an as-needed basis during the grading operations. Operations performed during fine grading of the site included: 1) overexcavation of the cut/fill transition and cut building pads; 2) preparation of areas to receive fill; and 3) placement of compacted fill. Based on our observation and testing during the fine grading operations, the following items were noted: I . Site Preparation Due to the relatively short time span between the completion of the mass or rough grading I operations and the re-initiation of fine grading at the site, significant site preparation was not required. However, during the fine grading operations at the site, all areas to receive additional fill were scarified to a depth of approximately 6 to 12 inches and moisture conditioned to near I optimum moisture content prior to the placement of fill in accordance with the recommendations of the project geotechnical report (Leighton, 2004). I I -3- 4 I Leighton Ii ~ I I I I I I I 971009-025 Overexcavation of the Building Pads Overexcavation of the near-surface formational material was performed to eliminate the cut/fill transition conditions and remove potential expansive clayey bedrock materials beneath the planned structures. The cut portion of the building pads for Buildings No. 1, 6, 7, 8, 9 and 10 was overexcavated to a minimum depth of 5 feet below the finished grade elevation. The overexcavations were made at least 5 feet laterally outside the planned limits of the building footprint. After the overexcavations were made, the removal bottoms were scarified to a depth of approximately 6 to 12 inches, moisture-conditioned to a near optimum moisture content, and compacted to a minimum 90 percent relative compaction (based on American Standard of Testing and Materials [ASTM] Test Method D1557). The approximate bottom elevations and limits of fill of the building pad areas are presented on the As-Graded Geotechnical Map (Plate 1). I Fill Placement and Compaction I After the processing of the areas to receive additional fill, native soil was spread in 4- to 8-inch loose lifts; moisture conditioned as needed to attain a near-optimum moisture content, and compacted. Field density test results performed during the grading operations indicated the fill I soils were compacted to at least 90 percent of the maximum dry density in accordance with ASTM Test Method D1557. I Compaction of the fill soils was achieved by use of heavy-duty construction equipment (including rubber-tire compactors and 627 scrapers). Areas of fill in which field density tests indicated compactions less than the recommended relative compaction or where the soils exhibited nonuniformity or had field moisture contents less than approximately 1 to 2 percent below the laboratory optimum moisture content, were reworked. The reworked areas were recompacted, and re-tested until the recommended minimum 90 percent relative compaction and near-optimum moisture content was achieved. I Field Density Testing Field density testing and observations were performed using the Nuclear-Gauge Method I (ASTM Test Methods D2922 and D3017). The approximate test locations are shown on the As-Graded Geotechnical Map (Plate 1). The results of the field density tests are summarized in Appendix B. The field density testing was performed in general accordance with the I applicable ASTM Standards, the current standard of care in the industry, and the precision of the testing method itself. Variations in relative compaction should be expected from the results documented herein. I I -4- Leighton I 971009-025 I 0 Laboratory Testin Laboratory maximum dry density tests of representative on-site soils were performed in general I accordance with ASTM Test Method D1557. Expansion potential and soluble sulfate content tests of representative finish grade soils were performed in accordance with ASTM Test Method D4829 and standard geochemical methods, respectively. The laboratory test results I indicate the building pad finish grade soils possess a medium expansion potential and a negligible to moderate soluble sulfate content (per CBC/UBC criteria). The laboratory test results are presented in Appendix C. I Summary of As-Graded Geologic Conditions The geologic or geotechnical conditions encountered during the fine grading of the site were essentially as anticipated. A comprehensive summary of the geologic conditions (including I geologic units, geologic structure and faulting) is presented below. I Geologic Units I The geologic units encountered during the fine grading operations included existing artificial fill, and the Tertiary-aged Santiago Formation. The approximate limits of these units are presented on the As-Graded Geotechnical Map (Plate 1). I Artificial fill (placed during the mass grading operations) was encountered in the northern and western portions of the site. As encountered, the fill soils were generally a yellow-brown to I gray-brown, damp, medium dense, silty fine to coarse sand and lesser silty to sandy clays, place during the recent mass grading of the site. The maximum depth of fill placed during mass grading was approximately 35 feet along the western margin of the site (Leighton, 2004). I The Tertiary-aged Santiago Formation underlies the existing fill soils at the site and is exposed at-grade in the eastern portion of the site outside the limits of the proposed building pads. As I observed during the recent grading operations, the materials consist primarily of massively bedded sandstones and claystones/siltstones. The sandstone generally consisted of orange- brown (iron-oxide staining) to light brown, damp to moist, dense to very dense, silty very fine I to medium grained sandstone. The siltstones and claystones were generally olive-green to gray (unweathered), damp to moist, stiff to hard, moderately weathered, and occasionally fractured and moderately sheared. For the most part, the highly expansive claystone was removed by the I planning grading and exported off the site. I I -5- 4 I Leighton I 971009-025 Geologic Structure The general structure of the formational material appears to be near horizontal. Based on our geologic mapping during the mass grading operations, bedding within the Santiago Formation generally exhibited somewhat variable bedding with strikes ranging from northwest to northeast and dips typically 2 to 9 degrees to the southeast and northwest. Geologic mapping of the cut slope on the eastern side of the site during the fine grading operations indicated the bedding was horizontal to dipping slightly (2 to 3 degrees) to the east. Variable minor jointing and shearing of the bedrock materials was observed locally. I Landslides and Surficial Failures I Based on our observations during the mass grading operations (Leighton, 2004), as well as geologic mapping during the fine grading operations, there was no evidence or indication of landslides or other surficial failures within the subject property. Faulting As indicated in the Supplemental Geotechnical Report for the Bressi Ranch project (Leighton, 2001), there are no known major or active faults on or in the immediate vicinity of the site. Based on our observations during mass grading (Leighton, 2004), as well as geologic mapping during the fine grading operations, no evidence of active faulting was encountered within the affordable housing site. Ground Water Ground water or seepage was not encountered during the fine grading operations for Planning Area PA-15. However, unanticipated seepage or ground water conditions may occur after the completion of grading and establishment of site irrigation and landscaping. If these conditions should occur, steps to mitigate the seepage should be made on a case-by-case basis. Subdrain systems were installed along the bottom of the tributary canyons within Planning Area PA-15 during the mass grading operations (Leighton, 2004). Summary of Conclusions The fine-grading operations for the affordable housing site at the Bressi Ranch development have been performed in general accordance with the project geotechriical reports (Appendix A), geotechnical recommendations made during fine grading, and the City of Carlsbad requirements. It is our opinion that the subject site is suitable for its intended residential use provided the -6- 4 Leighton I I I I 971009-025 recommendations included herein and in the project geotechnical report (Leighton, 2004) are incorporated into the design and construction of the proposed structures and associated improvements. The following is a summary of our conclusions concerning the fine grading of the subject site: Geotechnical conditions encountered during the fine grading operations were generally as anticipated. Based on our review of the grading operations, the geotechnical aspects of the site were addressed in general accordance with the requirements of the City of Carlsbad and standard practices in the industry. Site preparation and removals were geotechnically observed. The building pads of Building No. 1, 6, 7, 8, 9, and 10 were overexcavated and replaced with compacted fill. The overexcavation eliminated the cut/fill transition condition and/or removed expansive formational materials present at-grade within the limits of the building pads. Fill soils were derived from on-site materials. Our field density testing indicates the fill soils were placed and compacted to at least 90 percent relative compaction (based on ASTM Test Method D1557) at near optimum moisture content in accordance with the project recommendations and the requirements of the City of Carlsbad. No landslides or evidence of landsliding was observed during mass grading (Leighton, 2004) or the recent fine grading operations. No active faults or evidence of active faulting was observed within the affordable housing site during the fine grading operations or encountered during the previous investigations or mass grading operations. Ground water was not encountered or anticipated during the mass or fine grading operations. The expansion potential of the finish grade soils of the building pads was tested and found to be in the medium expansion potential range (per 2001 CBC, Table 18A-1-B). The potential for soluble sulfate attack (on Type Jill cement) is considered negligible to moderate based on the UBC/CBC criteria (CBSC, 2001). The soluble sulfate content test results should be supplied to the concrete contractor to mitigate the effects of the soluble sulfates in the onsite soils. Recommendations Based on the results of our geotechnical observation and testing during the fine grading operations of the affordable housing site, the site conditions were essentially as anticipated. Therefore, the recommendations previously presented in our geotechnical report of mass grading for the site -7- 4 I Leighton 1 971009-025 I (Leighton, 2004) relative to the post grading and construction phases of site development are still considered applicable and should be adhered to during future development of the site. The previous recommendations with some minor modifications (based on the results of our fine grading I operations and site-specific laboratory testing) are presented herein. I Earthwork We anticipate that future earthwork at the site will consist of site preparation, utility trench I excavation and backfill, retaining wall backfill, and driveway and parking area pavement section preparation and compaction. We recommend that the earthwork on site be performed in accordance with the following recommendations, the General Earthwork and Grading I Specifications for Rough Grading included in Appendix D, and the City of Carlsbad grading requirements. In case of conflict, the following recommendations shall supersede those in I Appendix D. The contract between the developer and earthwork contractor should be worded such that it is the responsibility of the contractor to place the fill properly and in accordance with the recommendations of this report and the specifications in Appendix D, notwithstanding I the testing and observation of the geotechnical consultant. If the length of time between the completion of grading and the construction of the I improvements is longer than six months, we recommend that the areas be evaluated by the geotechnical consultant and, if needed, the finish grade soils should be scarified a minimum of 12 inches, moisture-conditioned to 2-percent above the optimum moisture-content and I recompacted to a minimum 90 percent relative compaction (based on ASTM Test Method D1557). I The on-site soils are generally suitable for use as compacted fill provided they are free or organic material, debris, and rock fragments larger than 8 inches in maximum dimension. We do not recommend that high or very high expansive soils be utilized as fill for the building pads I (unless special foundation design considerations are implemented) or as retaining wall backfill. In general, all fill soils should be brought to 2-percent over the optimum moisture content and compacted in uniform lifts to at least 90 percent relative compaction based on the laboratory I maximum dry density (ASTM Test Method D1557). The optimum lift thickness required to produce a uniformly compacted fill will depend on the type and size of compaction equipment used. In general, fill should be placed in lifts not exceeding 8 inches in compacted thickness. I Placement and compaction of fill should be performed in general accordance with Appendix D, the current City of Carlsbad grading ordinances, sound construction practices, and the geotechnical recommendations presented herein. I I .. Excavations Excavations of the on-site materials may generally be accomplished with conventional heavy- duty earthwork equipment. It is not anticipated that blasting will be required or that significant I -8- 40 I Leighton I, 971009-025 I quantities of oversized rock (i.e. rock with maximum dimensions greater than 8 inches) will be generated during future grading. However, localized cemented zones within the cut areas and oversized rock placed within the compacted fill may be encountered on the site that may require I heavy ripping. If oversized rock is encountered, it should be placed in accordance with the recommendations presented in Appendix D, hauled offsite, or placed in non-structural or landscape areas. Due to the relatively dense characteristics of the on-site soils, temporary excavations such as utility trenches in the on-site soils should remain stable for the period required to construct the utility, provided they are constructed and monitored in accordance with OSHA requirements. Residential Foundation Design Considerations The proposed foundations and slabs of the proposed structures should be designed in accordance with structural considerations and recommendations presented herein. Since soils of medium expansion potential are present on all of the building pads and areas of significant fill thickness differentials within the limits of Buildings No. 2 through 4 are present on the site, we have provided recommendations for the utilization of post-tensioned slab and foundation systems. We recommend that the post-tensioned slabs be designed in accordance with the following design parameters presented on Table 1 and criteria of the current edition of the Uniform Building Code/California Building Code. The post-tensioned foundations should be designed in accordance with building pad specific expansion potential. I The post-tensioned foundations and slabs should be designed in accordance with structural considerations. Continuous footings with a minimum width of 12 inches and a minimum depth of 18 or 30 inches below adjacent (as indicated on Table 1) may be designed for a I maximum allowable bearing pressure of 2,000 pounds per square foot if founded into competent formational soils or properly compacted fill soils. The allowable bearing capacity may be increased by one-third for short-term loading such as wind or seismic forces. Where I the foundation is within 4 feet (horizontally) of adjacent drainage swales, the adjacent footing should be embedded a minimum depth of 12 inches below the swale flowline. I I I I I -9- 4 i Leighton I 971009-025 Table 1 Post-Tensioned Foundation Design Recommendations Post-Tension Design Category I Category* Category II Category III Category IV Lot Numbers None Buildings 1 and None Buildings 2 5 through 10 through 4 (1) Minimal Fill (1) Minimal Fill (1) Minimal Fill (1) Significant Fill Thickness; or Thickness; or Thickness; or Thickness and/or (2) Minimal Fill (2) Minimal Fill Minimal Fill Significant Fill Differential; and Differential; and Differential; and Differential Design Criteria Very Low to (3) Medium (3) High Regardless of the Expansion Low Expansion Expansion Expansion Potential/Index or Potential Potential Potential High Expansion (Expansion (Expansion (Expansion Potential (Expansion Index less than Index between Index between Index greater than 50) 51 and 90) 91 and 130) 131) Edge Moisture Center Lift: 5.5 feet 5.5 feet 5.5 feet 5.5 feet Variation, Edge em Lift: 2.5 feet 3.0 feet 4.5 feet 5.5 feet Differential Center Lift: 1.0 inches 2.0 inches 3.0 inches 4.0 inches Swell, Ym Edge Lift: 0.4 inches 0.8 inches 1.2 inches 1.5 inches Angular Distortion 1/800 1/600 1/600 1/500 Value: Allowable Bearing Capacity: 2,000 psf Perimeter Footing 12 inches 18 inches 1 24 inches 1 30 inches Depth: *per the Post-Tension Foundation Plan by Davidson Reinforcing dated February 6, 2004 (Davidson, 2004). The post-tension slabs should be a minimum of 5 inches thick. The slabs should be underlain by a minimum of 2 inches of clean sand (sand equivalent greater than 30) that is in turn underlain by plastic sheeting (10-mu) and an additional 2 inches of clean sand. The plastic sheeting should be sealed at all penetrations and laps. Moisture vapor transmission may be additionally reduced by use of concrete additives. Moisture barriers (i.e. plastic sheeting) can retard, but not eliminate moisture vapor movement from the underlying soils up through the slabs. We recommend that the floor covering installer test the moisture vapor flux rate prior to attempting _10- Leighton 971009-025 applications of the flooring."Breathable" floor coverings should be considered if the vapor flux rates are high. A slipsheet or equivalent should be utilized above the concrete slab if crack- sensitive floor coverings (such as ceramic tiles, etc.) are to be placed directly on the concrete slab. Our experience indicates that use of reinforcement in slabs and foundations will generally reduce the potential for drying and shrinkage cracking. However, some cracking should be expected as the concrete cures. Minor cracking is considered normal; however, it is often aggravated by a high water/cement ratio, high concrete temperature at the time of placement, small nominal aggregate size, and rapid moisture loss due to hot, dry and/or windy weather conditions during placement and curing. Cracking due to temperature and moisture fluctuations can also be expected. The use of low slump concrete (not exceeding 4 to 5 inches at the time of placement) can reduce the potential for shrinkage cracking and the action of tensioning the tendons can close small shrinkage cracks. In addition to the careful control of water/cement ratios and slump of concrete, application of 50 percent of the design post-tensioning load within three to four days of slab pour is found to be an effective method of reducing the cracking potential. The slab subgrade soils underlying the post-tensioned foundation systems should be presoaked as indicated in the following section prior to placement of the moisture barrier and slab concrete. Moisture Conditioning The slab subgrade soils underlying the post-tensioned foundation systems of the proposed structures should be presoaked in accordance with the recommendations presented in Table 2 prior to placement of the moisture barrier and slab concrete. The subgrade soil moisture content should be checked by a representative of Leighton and Associates prior to slab construction. Presoaking or moisture conditioning may be achieved in a number of ways, but based on our professional experience, we have found that minimizing the moisture loss of pads that have been completed (by periodic wetting to keep the upper portion of the pad from drying out) and/or berming the lot and flooding if for a short period of time (days to a few weeks) are some of the more efficient ways to meet the presoaking requirements. If flooding is performed, a couple of days to let the upper portion of the pad dry out and form a crust so equipment can be utilized should be anticipated. I I I I -11- 4 I Leighton I I I 971009-025 Table 2 Presoaking Recommendations Based on Finish Grade Soil Expansion Potential Expansion Building Numbers Potential (UBC Presoaking Recommendations 18-I-B) 19 percent moisture content to a I through 10 Medium minimum depth of 18 inches Seismic Design Parameters The site lies within Seismic Zone 4, as defined in the UBC, 1997 edition. The nearest known active fault is the Rose Canyon Fault Zone, which is considered a Type B Seismic Source (per 1997 UBC criteria), is located approximately 7.0 miles (or 11.2 kilometers) west of the site. The closest Type A Seismic Source is the Julian segment of the Elsinore Fault Zone, which is located approximately 23.5 miles (or 38 kilometers) east of the site. The following data should be considered for the seismic analysis of the proposed structures: Causative Fault: Rose Canyon Fault Zone Maximum Magnitude: 7.2 Seismic Source Type: B Seismic Zone Factor: 0.40 Soil Profile Type: Sc Near Source Factors: Na= 1.0/Nv = 1.0 Foundation Setback We recommend a minimum horizontal setback distance from the face of slopes or adjacent retaining walls for all structural foundations, footings, and other settlement-sensitive structures as indicated on Table 3. This distance is measured from the outside bottom edge of the footing, horizontally to the slope face and is based on the slope height and type of soil. However, the foundation setback distance may be revised by the geotechnical consultant on a case-by-case basis if the geotechnical conditions are different than anticipated. - 4 12- Leighton 971009-025 Table 3 Minimum Foundation Setback from Slope Faces Slope Height EMinimum Recommended Foundation Setback Less than 5 feet 5 feet 5to15feet 7feet Please note that the soils within the structural setback area possess poor lateral stability, and improvements (such as retaining walls, sidewalks, fences, pavements, etc.) constructed within this setback area may be subject to lateral movement and/or differential settlement. Potential distress to such improvements may be mitigated by providing a deepened footing or a pier and grade beam foundation system to support the improvement. The deepened footing should meet the setback as described above. Lateral Earth Pressures The recommended lateral pressures for very low to low import material as well as the onsite medium expansive soil (expansion index between 51 and 90 per CBC Table 18-1-B) and level or sloping backfill are presented on Table 4. High to very high expansive soils (having an expansion potential greater than 91 per UBC Table 18-I-13) should not be used as backfill soils on the site. -13- 4 Leighton 971009-025 Table 4 Lateral Earth Pressures Equivalent Fluid Weight (pcf) Import Very Low to Low Expansive Soils On-Site Medium Expansive Soils Conditions Expansion Index less than 50 (import) Expansion Index between 51 and 90 (on-site) Level 2:1 Slope Level 2:1 Slope Active 35 55 60 70 At-Rest 55 65 70 80 Passive 350 150 350 150 Embedded structural walls should be designed for lateral earth pressures exerted on them. The magnitude of these pressures depends on the amount of deformation that the wall can yield under load. If the wall can yield enough to mobilize the full shear strength of the soil, it can be designed for 'active" pressure. If the wall cannot yield under the applied load, the shear strength of the soil cannot be mobilized and the earth pressure will be higher. Such walls should be designed for "at rest" conditions. If a structure moves toward the soils, the resulting resistance developed by the soil is the "passive" resistance. The above noted passive resistance assumes an appropriate setback per the section entitled "Foundation Setback" as discussed above. For design purposes, the recommended equivalent fluid pressure for each case for walls founded above the static ground water and backfilled with soils of very low to low expansion potential or medium expansion potential is provided on Table 4. The equivalent fluid pressure values assume free-draining conditions. If conditions other than those assumed above are anticipated, the equivalent fluid pressures values should be provided on an individual-case basis by the geotechnical engineer. The geotechnical and structural engineer should evaluate surcharge-loading effects from the adjacent structures. All retaining wall structures should be provided with appropriate drainage and appropriately waterproofed. The outlet pipe should be sloped to drain to a suitable outlet. Typical wall drainage design is illustrated in Appendix D. For sliding resistance, the friction coefficient of 0.35 may be used at the concrete and soil interface. In combining the total lateral resistance, the passive pressure or the frictional resistance should be reduced by 50 percent. Wall footings should be designed in accordance with structural considerations. The passive resistance value may be increased by one-third when -14- 4 Leighton I I I I I I I I I I I I I I I I I I I I 971009-025 I considering loads of short duration including wind or seismic loads. The horizontal distance between foundation elements providing passive resistance should be minimum of three times the depth of the elements to allow full development of these passive pressures. The total depth of retained earth for the design of cantilever walls should be the vertical distance below the ground surface measured at the wall face for stem design or measured at the heel of the footing for overturning and sliding. All wall backcuts should be made in accordance with the current OSHA requirements. The granular and native backfill soils should be compacted to at least 90 percent relative I compaction (based on ASTM Test Method D1557). The granular fill should extend horizontally to a minimum distance equal to one-half the wall height behind the walls. The walls should be constructed and backfilled as soon as possible after backcut excavations. Prolonged exposure of backcut slopes may result in some localized slope instability I Foundations for retaining walls in competent formational soils or properly compacted fill should be embedded at least 18 inches below lowest adjacent grade. At this depth, an allowable bearing capacity of 2,000 psf may be assumed. Fences and Freestanding walls I Footings for freestanding walls should be founded a minimum of 18 inches below lowest adjacent grade (or 36 inches for walls founded on high to very high expansive soils). To reduce I the potential for unsightly cracks in freestanding walls, we recommend inclusion of construction joints at a maximum of 15-foot intervals. This spacing may be altered in accordance with the recommendations of the structural engineer, based on wall reinforcement I details. Our experience on similar sites in older developments indicates that walls on shallow I foundations near the top-of-slopes tend to tilt excessively over time as a result of slope creep. If the effects of slope creep on top-of-slope walls are not deemed acceptable, one or a combination of the options provided in the following paragraphs should be utilized in the I design of such structures, based on the desired level of mitigation of creep-related effects on them. I A relatively inexpensive option to address creep related problems in top-of-slope walls and fences is to allow some degree of creep damage and design the structures so that tilting or cracking will be less visually obvious, or such that they may be economically repaired or replaced. If, however, a better degree of creep mitigation is desired, the walls and fences may be provided with the deepened footings to met the foundation setback criteria laid out in Figure 18-1-1 of the 1997 UBC edition, or these structures may be constructed to accommodate potential movement. I 400, I -15 WV - I Leighton I 971009-025 I Under certain circumstances, an effective solution to minimize the effects of creep on top-of- slope walls and fences is to support these structures on a pier-and-grade-beam system. The piers normally consist of minimum 12-inch diameter cast-in-place caissons spaced at a maximum of I 8 feet on center, and connected together by a minimum 12-inch-thick grade beam at a shallow depth. The piers are typically at least 10 feet deep for medium or high expansive soil. The steel reinforcement for the system should be designed with consideration of wall/fence type and I loading. Walls or fences aligned essentially perpendicular to the top of the slope are normally supported on the pier-and-grade-beam system for at least that part of the wall that is within 15 feet from the top-of-slope. Caisson support is recommended for all top-of-slope walls where I slopes are greater than 10 feet in height and the slopes consist of high or very high expansive soils. Concrete Driveways and Other Flatwork Concrete driveways and nonstructural flatwork (such as walkways, swimming pool decks, patio slabs, etc.) have a high potential for cracking or lifting due to change in soil volume. To I reduce the potential for excessive cracking, the concrete should be designed in accordance with the minimum recommendations outlined in Table 5. The recommendations presented in Table 5 assume very low to medium expansive soils. The recommendations will reduce the I potential for cracking and promote cracking along construction joints, but will not eliminate all cracking or lifting. Thickening the concrete and/or adding additional reinforcement will also help to reduce cosmetic distress. A flexible seal should be provided between the garage I and the driveway. Recommendations concerning concrete flatwork on high to very high expansive subgrade I soils can be provided at a later date, if necessary. In the event that high to very high expansive soils are present at-grade, recommendations concerning concrete placed on high to very high expansive soils may include overexcavation of the subgrade soils and moisture conditioning I to a 6-percent over the optimum moisture content prior to the placement of the concrete flatwork and/or providing a minimum 4-inch thick aggregate base layer beneath the concrete flatwork. I I I LI I I -16- 4 Leighton I 971009-025 I I I I I I I -17- Leighton I Table 5 Recommendations for Nonstructural Concrete Flatwork on Medium Expansive Soils City Sidewalk Item Sidewalks Garage Driveways Patios! Entryways Curb and Gutters Minimum 4 inches 5 inches (full) 5 inches (full) City Standard Thickness (nominal) Optimum moisture Optimum Optimum Presaturation content to 12 inches moisture content moisture content City Standard to 12 inches to 12 inches Minimum 6x6 #6 welded wire No. 3 at 24 inches No. 3 at 24 inches Reinforcement mesh at center of slab on centers on centers City Standard Thickened Edge Not required Not required Not required City Standard Saw cut or deep tool Saw cut every 6 Deep tool joint at Crack Control joint to a minimum of 1!3 the concrete feet, to 1!3 10' maximum City Standard thickness concrete thickness spacing Maximum Joint 10 feet or quarter Spacing 5 feet cut whichever is 5 feet City Standard closer Aggregate Base Not required 4 inches Not required City Standard I I I I I I I I I I I 971009-025 I Concrete In-place concrete is subject to adverse conditions such as unsightly cracking, excessive water I vapor transmission, sulfate attack, efflorescence, and other adverse conditions. Adherence to the following guidelines will help mitigate against the above adverse hazards. I 1) Exposure to sulfate-containing solutions: The soluble sulfate content of the finish grade soils on the building pads range I from a negligible to moderate range based on 1997 Uniform Building Code criteria. Sulfate content testing (Appendix C) indicates the finish grade soils of Building No. 1, 3, 4, and 6 through 10 have a negligible sulfate exposure I content while the soils on Buildings No. 2 and 5 have a moderate sulfate exposure. Comply with 1997 UBC Table 19-A-4; and Maintain a concrete water/cement ratio of less than 0.5. 2) Drying shrinkage cracking: I • Follow recommendations of ACI 332.R for residential construction, as appropriate; I . Maintain concrete water/cement ratio less than 0.5. Use minimum cement required to achieve desired strength; Provide effective concrete curing for seven days after placing; I . Design control joints into slab; and Do not place concrete on hot, windy low-humidity days. I 3) Reduction of vapor transmission: Maintain concrete water/cement ratio less than 0.5. Avoid construction punctures of vapor barriers; I • Seal vapor barrier joints; Extend vapor barrier into footing/grade beam excavation (not covering bottom I of excavation); Prevent excessive irrigation of landscaping; and Use floor-covering adhesives that are not water-soluble. PreliminaEy Pavement Design The appropriate Asphalt Concrete (AC) and Class 2 aggregate base (AB) pavement section will depend on the type of subgrade soil, shear strength, traffic load, and planned pavement life. Since an evaluation of the actual subgrade soils cannot be made at this time, we have assumed an R-value of 12 and a Traffic Index (TI) of 6.0. The pavement section presented on Table 6 is to be used for preliminary planning purposes only. Final pavement designs should be completed 4 -18- Leighton I 971009-025 in accordance with the City of Carlsbad design criteria after R-value tests have been performed on the actual subgrade materials. Table 6 Preliminary Pavement Section Design Traffic Index Assumed R-Value Preliminary Pavement Section 6.0 12 4 inches AC over 12 inches Class 2 Aggregate Base Asphalt Concrete and Class 2 aggregate base should conform to and be placed in accordance with the latest revision of California Department of Transportation Standard Specifications. Prior to placing the pavement section, the subgrade soils should have a relative compaction of at least 95 percent to a minimum depth of 12 inches (based on ASTM Test Method D1557). Aggregate Base should be compacted to a minimum of 95 percent relative compaction (based on ASTM Test Method D1557) prior to placement of the AC. If pavement areas are adjacent to heavily watered landscaping areas, we recommend some I measures of moisture control be taken to prevent the subgrade soils from becoming saturated. It is recommended that the concrete curbing, separating the landscaping area from the pavement, I extend below the aggregate base to help seal the ends of the sections where heavy landscape watering may have access to the aggregate base. Concrete swales should be designed if asphalt pavement is used for drainage of surface waters. I Slope Maintenance Guidelines I It is the responsibility of the owner to maintain the slopes, including adequate planting, proper irrigation and maintenance, and repair of faulty irrigation systems. To reduce the I potential for erosion and slumping of graded slopes, all slopes should be planted with ground cover, shrubs, and plants that develop dense, deep root structures and require minimal irrigation. Slope planting should be carried out as soon as practical upon completion of I grading. Surface-water runoff and standing water at the top-of-slopes should be avoided. Oversteepening of slopes should be avoided during construction activities and landscaping. Maintenance of proper lot drainage, undertaking of property improvements in accordance I with sound engineering practices, and proper maintenance of vegetation, including regular slope irrigation, should be performed. Slope irrigation sprinklers should be adjusted to provide maximum uniform coverage with minimal of water usage and overlap. Overwatering I and consequent runoff and ground saturation should be avoided. If automatic sprinklers systems are installed, their use must be adjusted to account for rainfall conditions. I I _19- Leighton I I I I I I 11 I 971009-025 Trenches excavated on a slope face for any purpose should be properly backfilled and compacted in order to obtain a minimum of 90 percent relative compaction, in accordance with ASTM Test Method D1557. Observation/testing and acceptance by the geotechnical I consultant during trench backfill is recommended. A rodent-control program should be established and maintained. Prior to planting, recently graded slopes should be temporarily protected against erosion resulting from rainfall, by the implementing slope protection I measures such as polymer covering, jute mesh, etc. I Control of Surface Water and Drainage Surface drainage should be carefully taken into consideration during precise grading, I landscaping, and building construction. Positive drainage (e.g., roof gutters, downspouts, area drain, etc.) should be provided to direct surface water away from structures and towards the street or suitable drainage devices. Ponding of water adjacent to structures should be avoided; I roof gutters, downspouts, and area drains should be aligned so as to transport surface water to a minimum distance of 5 feet away from structures. The performance of structural foundations is I dependent upon maintaining adequate surface drainage away from structures. Water should be transported off the site in approved drainage devices or unobstructed swales. I We recommend that the minimum flow gradient for the drainage be 1-percent for area drains and paved drainage swales; and 2-percent for unpaved drainage swales. We recommend that where structures will be located within 5 feet of a proposed drainage swale, the surface I drainage adjacent to the structures be accomplished with a gradient of at least 3-1/2 percent away from the structure for a minimum horizontal distance of 3 feet. Drainage should be further maintained by a swale or drainage path at a gradient of at least 1-percent for area I drains and paved drainage swales and 2-percent for unpaved drainage swales to a suitable collection device (i.e. area drain, street gutter, etc.). We also recommend that structural footings within 4 feet of the drainage swale flowline be deepened so that the bottom of the I footing is at least 12 inches below the flow-line of the drainage swale. In places where the prospect of maintaining the minimum recommended gradient for the drainage swales and the construction of additional area drains is not feasible, provisions for specific recommendations may be necessary, outlining the importance of maintaining positive drainage. The impact of heavy irrigation or inadequate runoff gradient can create perched water I conditions, resulting in seepage or shallow groundwater conditions where previously none existed. Maintaining adequate surface drainage and controlled irrigation will significantly reduce the potential for nuisance-type moisture problems. To reduce differential earth I movements (such as heaving and shrinkage due to the change in moisture content of foundation soils, which may cause distress to a structure or improvement), the moisture content of the soils surrounding the structure should be kept as relatively constant as possible. 1 I I 20- i Leighton Li] 971009-025 I All area drain inlets should be maintained and kept clear of debris in order to function properly. In addition, yard landscaping should not cause any obstruction to the yard drainage. Rerouting of yard drainage pattern and/or installation of area drains should be performed, if necessary. A I qualified civil engineer or a landscape architect should be consulted prior to rerouting of drainage. Landscaping and Post-Construction I Landscaping and post-construction practices carried out by the owner(s) and their representative bodies exert significant influences on the integrity of structures founded on expansive soils. Improper landscaping and post-construction practices, which are beyond the control of the I geotechnical engineer, are frequently the primary cause of distress to these structures. Recommendations for proper landscaping and post-construction practices are provided in the following paragraphs within this section. Adhering to these recommendations will help in I minimizing distress due to expansive soils, and in ensuring that such effects are limited to cosmetic damages, without compromising the overall integrity of structures. The I recommendations provided herein have been developed in general accordance with the guidelines provided within the Post-Tensioning Institute's (1996) recommendations for the design and construction of post-tensioned slabs-on-ground. I Initial landscaping should be done on all sides adjacent to the foundation of a structure, and adequate measures should be taken to ensure drainage of water away from the foundation. If I larger, shade providing trees are desired, such trees should be planted away from structures (at a minimum distance equal to half the mature height of the tree) in order to prevent penetration of the tree roots beneath the foundation of the structure. Locating planters adjacent to buildings or structures should be avoided as much as possible. If planters are utilized in these locations, they should be properly designed so as to prevent I fluctuations in the moisture content of subgrade soils. Planting areas at grade should be provided with appropriate positive drainage. Wherever possible, exposed soil areas should be above paved grades. Planters should not be depressed below adjacent paved grades unless I provisions for drainage, such as catch basins and drains, are made. Adequate drainage gradients, devices, and curbing should be provided to prevent runoff from adjacent pavement or walks into planting areas. Watering should be done in a uniform, systematic manner as equally as possible on all sides of the foundation, to keep the soil moist. Irrigation methods should promote uniformity of I moisture in planters and beneath adjacent concrete flatwork. Overwatering and underwatering of landscape areas must be avoided. Areas of soil that do no have ground cover may require more moisture, as they are more susceptible to evaporation. Ponding or trapping of water in I localized areas adjacent to the foundations can cause differential moisture levels in subsurface soils and should, therefore, not be allowed. Trees located within a distance of 20 feet of foundations would require more water in periods of extreme drought, and in some cases, a root 1 -21- Leighton I 971009-025 I injection system may be required to maintain moisture equilibrium. During extreme hot and dry periods, close observations should be carried out around foundations to ensure that adequate watering is being undertaken to prevent soil from separating or pulling back from the I foundations. Construction Observation and Testing Construction observation and testing should be performed by the geotechnical consultant during I the remaining grading operations, future excavations and foundation or retaining wall construction on the graded portions of the site. Additionally, footing excavations should be observed and moisture determination tests of subgrade soils should be performed by the 1 geotechnical consultant prior to the pouring of concrete. Foundation design plans should also be reviewed by the geotechnical consultant prior to excavations. Limitations The presence of our field representative at the site was intended to provide the owner with professional advice, opinions, and recommendations based on observations of the contractor's work. Although the observations did not reveal obvious deficiencies or deviations from project specifications, we do not guarantee the contractor's work, nor do our services relieve the contractor or his subcontractor's work, nor do our services relieve the contractor or his subcontractors of their responsibility if defects are subsequently discovered in their work. Our responsibilities did not include any supervision or direction of the actual work procedures of the contractor, his personnel, or subcontractors. The conclusions in this report are based on test results and observations of the grading and earthwork procedures used and represent our engineering opinion as to the compliance of the results with the project specifications. -22- Leighton 971009-025 If you have any questions regarding our report, please contact this office. We appreciate this opportunity to be of service. Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. CESSI D. William D. Olson, RCE 45283 rn UJ Senior Project Engineer ce- Randall K. Wagne , CEG Director of Geology if NO. 62 H*I CERTIFIED I* \ ENGINEERING / Attachments: Plate 1 - As-Graded Geotecimical Map (In Pocket) GEOLOGIST1 Appendix A - References 4POF CAL Appendix B - Summary of Field Density Tests Appendix C - Laboratory Testing Procedures and Test Results I Appendix D - General Earthwork and Grading Specifications for Rough Grading Distribution: (10) Addressee -23- 4 Leighton rr. 44+ RO 00 -f- 00 N -" / - - V + 00 LN 1 4131 / N N N -- - / /•. 7 59 /,H /U1 N=4o -- ,Zz/N VS /• '. / VA H/H I /ini V N V V / • / I I I / ii / i V 7 / V / - I / /7\ /1 . L L / \ N INO I F LIZ 00 / 43A) / 7/ 86 I I 0 / V , - V / / / 39 /7=401 7 63 62 • I - - V - QD T 1.5 waIl 71 '/00 / 40- 370 11 / 70 / V = 16 / L3691 \ /N /+oo 0 / 1 I 0 40 80 SCALE FEET \I / H - 'V 'V LEGEND: GEOLOGIC UNITS: Af ARTIFICIAL FILL—DOCUMENTED BY LEIGHTON AND ASSOCIATES 7 ' isa TERTIARY SANTIAGO FORMATION (CIRCLED WHERE BURIED) - --- _- SYMBOLS: - APPROXIMATE LIMITS OF FILL I 387 APPROXIMATE ELEVATION OF REMOVAL BOTTOM 'V 92 APPROXIMATE LOCATION OF FIELD DENSITY TEST PLATE 1 I 9 _____ • maw ii' •- ___ pm . - - •i 4Jii It NOW Mani H H \ H2 Tsa C) / -.,...-V- ' / 'N—P /V '•••••••'V• N:. V. 'V, AS—GRADED GEOTECHNICAL MAP \ \/\ AFFORDABLE HOUSING SITE, PLANNING AREA PA-1 7 'V BRESSI RANCH, CARLSBAD, CALIFORNIA 'N Proj: 971009-025 Scale: 1"=40' [)ate: 6/25/04 " Eng/Geol: WDO/RKW Drafted By: BQT CP By: BQT MAP: I DIGITAL F1\E PROVIDED '/APRIL 9, 2004o (PDC, 2004a) Leighton and Associates, Inc.FP:\DRAFTlNG971009025\OF_6-21-04\PA-15.DWG (06-28-04 4:28:0PM) Plotted by: btran i 971009-025 I APPENDIX A References I California Building Standards Commission (CBSC), 2001, California Building Code, Volume I - I Administrative, Fire- and Life-Safety, and Field Inspection Provision, Volume II - Structural Engineering Design Provision, and Volume III - Material, Testing and InstallatiOn Provision, ICBO. I Davidson Reinforcing Company, 2004, Post-Tension foundation Plans for Bressi Ranch (PA-15), Carlsbad, CA, Sheets CVR, PTD, PT 1, and PT1-1, Job No. 1604, dated February 6, 2004. I Hart, E.W., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo Special Studies Zones Act of 1972 with Index to Special Studies Zones Maps: Department of Conservation, I Division of Mines and Geology, Special Publication 42. William Hezmalhalch Architects, 2003, Structural Plans, Bressi Ranch Affordable Housing, I Planning Area 15 Lot I Condominiums, Carlsbad, California, Sheets 51-1 and S- 1, Job No. 03121, dated June 23, 2003. International Conference of Building Officials (ICBO), 1997, Uniform Building Code, Volume I - Administrative, Fire- and Life-Safety, and Field Inspection Provisions, Volume II - Structural Engineering Design Provisions, and Volume III - Material, Testing and I Installation Provision, ICBO. Leighton and Associates, Inc., 1997, Preliminary Geotechnical Investigation, Bressi Ranch, Carlsbad, California, Project No. 4971009-002, dated July 29, 1997. 2001, Supplemental Geotechnical Investigation for Mass Grading, Bressi Ranch, Carlsbad, California, Project No. 971009-0015, dated March 14, 2001. I , 2004, As-Graded Report of Mass Grading, Affordable Housing Site, Northwest Portion of Planning Area PA-is, Bressi Ranch, Carlsbad, California, Project No. 971009-014, dated April 21, 2004. I Project Design Consultants (PDC), 2004a, Grading and Erosion Control Plans for Bressi Ranch Affordable Housing, Carlsbad, Tract No. 03-03, Carlsbad, California, 15 Sheets, I Drawing No. 415-3C, dated April 9, 2004. 2004b, Plans for the Improvement of Bressi Ranch Affordable Housing, Carlsbad I Tract No. 03-03, Carlsbad, California, 8 Sheets, Drawing No. 415-3, dated April 12, 2004. I I I A-i Li I 971009-025 APPENDIX B Summary of Field Density Tests Test No. Test of Test No. Test of Prefix Test of Abbreviations Prefix Test of Abbreviations (none) GRADING Natural Ground NO (SG) SUBGRADE Original Ground OG (AB) AGGREGATE BASE Existing Fill EF (CB) CEMENT TREATED BASE Compacted Fill CF (PB) PROCESSED BASE Slope Face SF (AC) ASPHALT CONCRETE Finish Grade FG Curb C (S) SEWER (SD) STORM DRAIN Gutter G (AD) AREA DRAIN Curb and Gutter CG (W) DOMESTIC WATER Cross Gutter XG (RC) RECLAIMED WATER Street ST (SB) SUBDRAIN Sidewalk SW (0) GAS Driveway D (E) ELECTRICAL Driveway Approach DA (T) TELEPHONE Parking Lot PL (J) JOINT UTILITY Electric Box Pad EB (I) IRRIGATION Bedding Material B Shading Sand S Main M Lateral L Crossing X Manhole MH Hydrant Lateral 1-IL Catch Basin / CB Riser R Inlet I (RW) RETAINING WALL (P) PRESATURATION (CW) CRIB WALL (LW) LOFFELL WALL Moisture Content M (SF) STRUCT FOOTING Footing Bottom F Backfill B Wall Cell C (IT) INTERIOR TRENCH Plumbing Backfill P Electrical Backfill E IN tcpicii IIuIIeai gauge iests mat were penormea in generai accoruance with most recent version of ASTM Test Methods D2922 and D3017. S represents sand cone tests that were performed in general accordance with most recent version of ASTM Test Method DI 556. 15A represents first retest of Test No. 15 15B represents second retest of Test No. 15 "0" in Test Elevation Column represents test was taken at the ground surface (e.g. finish grade or subgrade) "-1" in Test Elevation Column represents test was taken one foot below the ground surface B-i I Ul I I I I I I I I I I I I - - - - UFtAROF - - - - - - - ELD DENSITY TESTS Test Test Test Location Test Soil Dry Density Moisture (%) Relative (%) No. Date Of Northing Easting Elev (ft) Type Field Max Field Opt. Compaction Remarks 1 5/28/04 CF Building! Pad 1991128 6253528 372.0 17 103.4 114.0 17.1 14.5 91 2 5/28/04 CF Building 1 Pad 1991115 6253536 372.0 17 103.8 114.0 15.8 14.5 91 3 5/28/04 CF Building 1 Pad 1991143 6253530 374.0 17 105.1 114.0 15.6 14.5 92 4 5/28/04 CF Building 1 Pad 1991124 6253516 376.0 17 100.1 114.0 13.9 14.5 88 RTON4A 4A 5/28/04 CF Building! Pad 1991118 6253518 376.0 17 103.0 114.0 13.1 14.5 90 ' RTOF4 5 5/28/04 CF Building 2 Pad 1991296 6253505 387.0 17 105.4 114.0 14.6 14.5 92 6 5/28/04 CF Building 2Pad 1991267 6253563 388.0 17 ' 106.8 114.0 18.2 14.5 94 7 5/28/04 CF Building! Pad 1991133 6253546 379.0 17 106.4 114.0 14.7 14.5 93 8 6/1/04 CF Building Pad 1991506 6253485 391.0 10 164.3 112.5 17.4 16.0 93 9 6/1/04 CF Building 3 Pad 1991484 6253490 392.0 9 107.2 118.0 16.7 15.0 91 10 6/1/04 CF Building 3 Pad 1991434 6253498 390.0 9 106.8 118.0 16.5 15.0 91 11 6/1/04 CF Building 3 Pad 1991404 6253488 392.0 18 105.0 113.0 18.2 16.0 93 12 6/2/04 CF Building Pad 1991526 6253657 398.0 9 106.2 118.0 15.4 15.0 90 13 6/2/04 CF Buildings Pad, 1991561 6253664 398.0 18 103.7 113.0 16.0 16.0 92 14 6/2/04 CF Building 1 Pad 1991108 6253636 382.0 9 107.2 118.0 15.1 15.0 91 15 6/2/04 CF Building 1 Pad . 1991140 6253630 383.0 18 101.9 113.0 16.6 16.0 90 16 6/2/04 CF Building I Pad 1991162 6253612 385.0 18 104.1 113.0 17.2 16.0 92 17 6/2/04 CF Building 10 Pad 1991257 6253719 388.0 18 101.7 113.0 19.4 16.0 90 18 6/2/04 CF Building 10 Pad 1991282 6253695 390.0 9 105.8 118.0 16.7 15.0 90 19 6/2/04 CF Building 10 Pad , 1991215 6253719 388.0 9 107.2 118.0 16.9 15.0 91 20 6/3/04 CF Building 10 Pad 1991159 6253734 389.0 9 108.8 118.0 14.9 15.0 92 21 6/3/04 CF Building 10 Pad 19911.59 6253758 389.0 9 106.4 118.0 15.8 15.0 '90 22 6/3/04 CF Building 10 Pad 1991182 6253744 392.0 9 107.9 118.0 15.2 15.0 . 91 23 6/4/04 CF Building I Pad 1991125 6253494 385.0 18 103.7 113.0 17.2 16.0 92 24 6/4/04 ' CF Building I Pad 6253535 1991140 383.0 9 107.6 118.0 15.9 15.0 91 25 6/8/04 FG Building 1 Pad 1991128 6253508 . 0.0 9 106.9 118.0 17.4 15.0 91 26 6/8/04 FG Building I Pad 1991126 6253601 0.0 9 110.8 118.0 15.9 15.0 94 27 6/8/04 FG Building 1 Pad 1991128 6253615 0.0 9 109.7 118.0 16.2 15.0 93 28 6/8/04 FG Building Pad ' 1991301 6253615 0.0 19 110.0 118.0 14.9 15.0 93 29 6/8/04 FG Building Pad 1991303 6253564 '0.0 14 118.0 124.0 13.8 12.0 95 30 6/8/04 FG Building 2 Pad 1991308 6253512 0.0 19 108.9 118.0 14.7 15.0 92 31 6/8/04 FG Buildings Pad 1991408 6253688 0.0 18 102.8 113.0 17.4 16.0 91 Project Number: 971009025 Project Name: Bressi Ranch 25 Project Location: PA-15 . . Client: Greystone Page 1 of Lelgflton and Associates, Inc 6/23/2 10:57:03AM - - - - U flAR F L E - - - - - Test No. Test Date Test Of Location Northing Easting Test Elev (ft) Soil Type Dry Density Field Max Moisture (%) Field Opt. Relative (%) Compaction Remarks 32 6/8/04 FG Building 5 Pad 1991470 6253678 0.0 19 106.3 118.0 14.7 15.0 90 33 6/8/04 FG Building 5 Pad 1991525 6253681 0.0 19 108.1 118.0 14.3 15.0 92 34 6/8/04 CF Building Pad 1991164 6253954 390.0 18 103.4 113.0 17.0 16.0 92 35 6/8/04 CF Building 9Pad 1991168 6253929 390.0 18 103.3 113.0 18.6 16.0 91 36 6/9/04 CF Building Pad 1991137 6253889 391.0 18 103.5 113.0 16.7 16.0 92 37 6/9/04 CF Building 9Pad 1991161 6253859 392.0 19 108.6 118.0 15.9 15.0 92 38 6/9/04 CF Building 9Pad 1991186 6253832 393.0 9 107.4 118.0 16.3 15.0 91 39 6/9/04 CF Building 6Pad 1991556 6253865 398.0 18 103.3 113.0 16.7 16.0 91 40 6/9/04 . CF Building 6Pad 1991520 6253842 399.0 18 96.5 113.0 17.1 16.0 85 RTON40A 40A 6/9/04 CF Building Pad 1991525 6253847 399.0 18 104.8 113.0 16.5 16.0 93 RTOF40 41 6/10/04 CF Building 7 Pad 1991405 6253807 396.0 9 106.6 118.0 15.8 15.0 90 42 6/10/04 CF Building 7Pad 1991403 6253873 397.0 9 107.7 118.0 17.1 15.0 91 43 6/10/04 CF Building 7Pad 1991414 6253920 397.5 18 100.1 113.0 16.4 16.0 89 RTON43A 43A 6/10/04 CF Building 7Pad 1991408 6253912 397.5 18 102.9 113.0 16.8 16.0 91 RTOF43 44 6/10/04 CF Building 7 Pad 1991376 6253827 399.0 18 101.8 113.0 17.0 16.0 90 45 6/10/04 CF Building 7Pad 1991365 6253795 398.5 8 103.5 117.5 17.4 14.0 88 46 6/10/04 CF Building 4 Pad -1991501 6253564 392.5 18 101.5 113.0 16.1 16.0 90 47 6/10/04 FG Building Pad 1991524 6253605. 0.0 18 . 102.3 113.0 16.3 16.0 91 48 6/10/04 FG Building Pad 1991465 6253615 0.0 18 101.9 113.0 16.7 16.0 90 49 6/10/04 FG Building 4Pad 1991410 6253618 0.0 18 102.0 113.0 17.4 16.0 90 50 6/11/04 CF Building Pad 1991339 6253796 392.5 18 104.4 113.0 15.3 16.0 92 51 6/11/04 CF Building 8Pad 1991312 6253860 393.0 18 103.1 113.0 17.1 16.0 91 52 6/11/04 CF Building Pad 1991315 6253952 394.5 18 102.5 113.0 16.4 16.0 91 53 6/11/04 CF Building 8Pad 1991338 6253852 395.0 18 102.7 113.0 16.8 16.0 91 54 6/11/04 CF Building Pad 1991328 6253813 395.0 9 106.4 118.0 15.4 15.0 90 55 6/14/04 FG Building 3 Pad 1991520 6253488 0.0 2 114.0 122.5 9.6 11.5 93 56 6/14/04 FG Building 3 Pad 1991470 6253497 0.0 18 102.4 113.0 16.4 16.0 91 57 6/14/04 FG Building Pad . 1991406 6253502 0.0 18 103.5 113.0 15.9 16.0 92 58 6/14/04 FG Building 6Pad 1991554 6253904 0.0 9 107.3 118.0 14.7 15.0 91 59 6/14/04 FG Building 6 Pad 1991551 6253854 0.0 9 106.1 118.0 15.4 15.0 90 60 6/14/04 FG Building 6 Pad 1991555 6253789 0.0 18 103.4 113.0 16:1 16.0 92 61 6/14/04 FG Building 7 Pad 1991377 6253795 0.0 9 108.2 118.0 18.7 15.0 92 Project Number: 971009025 . . Project Name: Bressi Ranch 25 . Project Location: PA-15 Client: Greystone Page 2 of 3 . Leighton and Associates, Inc 6/23/2 10:57:04AM Test No. Test Date Test Of Location Northing Easting Test Elev (ft) Soil Type Dry Density Field Max Moisture (%) Field Opt. Relative (%) Compaction Remarks 62 6/14/04 FG Building 7 Pad 1991375 6253845 0.0 18 102.7 113.0 15.4 16.0 91 63 6/14/04 FG Building 7Pad 1991378 6253905 0.0 18 104.8 113.0 16.2 16.0 93 64 6/14/04 FG Building 8 Pad 1991326 6253882 0.0 20 104.2 116.0 16.3 14.0 90 65 6/14/04 FG Building 8Pad 1991323 6253844 0.0 16 105.6 117.0 15.9 14.0 90 66 6/14/04 FG Building 8 Pad 1991322 6253940 0.0 23 107.2 119.0 15.8 13.0 90 67 6/14/04 FG Building 9Pad 1991142 6253851 0.0 21 106.5 118.0 16.3 13.0 90 68 6/14/04 FG Building 9Pad 1991144 6253916 0.0 9 106.8 118.0 16.7 15.0 91 69 6/14/04 FG Building 9 Pad 1991152 6253959 0.0 16 105.3 117.0 15.5 14.0 90 70 6/14/04 FG Building 10 Pad 1991167 6253748 0.0 18 103.0 113.0 17.2 16.0 91 71 6/14/04 FG Building 10 Pad 1991271 6253718 0.0 16 105.2 117.0 16.9 14.0 90 72 6/14/04 FG Building 10 Pad 1991204 6253736 0.0 18 103.6 113.0 15.1 16.0 92 73 6/15/04 FG Building 1 Garage Pad 1991155 6253572 0.0 4 112.4 120.5 12.5 12.5 93 74 6/15/04 FG Building i Garage Pad 1991148 6253517 0.0 21 106.7 118.0 14.6 13.0 90 75 6/15/04 FG Building 2 Garage Pad 1991273 6253529 0.0 4 108.3 120.5 13.4 12.5 90 76 6/15/04 FG Building 2 Garage Pad 1991274 6253614 0.0 4 108.9 120.5 14.2 12.5 90 77 6/15/04 FG Building 3 Garage Pad 1991512 6253521 0.0 17 103.3 114.0 13.7 14.5 91 78 6/15/04 FG Building Garage Pad 1991414 6253527 0.0 17 104.4 114.0 14.8 14.5 92 79 6/15/04 FG Building 4 Garage Pad 1991522 6253576 0.0 11 108.7 120.0 13.5 13.0 91 80 6/15/04 FG Building 4 Garage Pad 1991431 6253579 0.0 22 113.7 124.0 12.5 12.0 92 81 6/15/04 FG Buildings Garage Pad 1991416 6253711 0.0 4 108.9 120.5 13.8 12.5 90 82 6/15/04 FG Building 5 Garage Pad 1991461 6253705 0.0 22 112.5 124.0 12.6 12.0 91 83 6/15/04 FG Building 6 Garage Pad 1991523 6253805 00 16 105.6 117.0 18.4 14.0 90 84 6/15/04 FG Building6 Garage Pad 1991525 6253902 0.0 16 106.2 117.0 17.6 14.0 91 85 6/15/04 FG Building 7 Garage Pad 1991403 6253907 0.0 16 106.3 117.0 16.3 14.0 91 86 6/15/04 FG Building 7 Garage Pad 1991409 6253792 0.0 20 104.0 116.0 17.6 14.0 90 87 6/15/04 FG Building 8 Garage Pad 1991290 6253838 0.0 18 101.9 113.0 17.2 16.0 90 88 6/15/04 'FG Building 8 Garage Pad 1991304 6253905 0.0 18 102.8 113.0 16.6 16.0 91 89 6/15/04 FG Building 9 Garage Pad 1991182 6253916 0.0 23 107.5 119.0 16.4 13.0 90 90 6/15/04 FG Building 9 Garage Pad 1991171 6253839 0.0 23 106.6 119.0 17.3 13.0 90 91 6/15/04 FG Building 10 Garage Pad 1991265 6253755 0.0 4 108.6 120.5 16.1 12.5 90 92 6/15/04 FG Building 10 Garage Pad 1991192 6253758 0.0 23 107.7 119.0 16.9 13.0 91 Project Number: 971009025 Project Name: Bressi Ranch 25 Project Location: PA-15 Client: Greystone Page 3 of 3 Leighton and Associates, Inc 6/23/2 10:57:04AM I 971009-025 I APPENDIX C Expansion Index Tests: The expansion potential of selected materials was evaluated by the I Expansion Index Test, U.B.C. Standard No. 18-2 and/or ASTM Test Method 4829. Specimens are molded under a given compactive energy to approximately the optimum moisture content and I approximately 50 percent saturation or approximately 90 percent relative compaction. The prepared 1-inch thick by 4-inch diameter specimens are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric equilibrium is reached. The results of these tests are presented in the table below: Sample Location Soil Type Expansion Expansion Index Potential* Building Pad 1 Olive-gray silty SAND 60 Medium Building Pad 2 Light brown silty SAND 63 Medium Building Pad 3 Olive-brown silty to 73 Medium clayey SAND Building Pad 4 Olive-brown silty to 58 Medium clayey SAND Building Pad 5 Olive-brown silty to 71 Medium clayey SAND Building Pad 6 Olive-brown silty to 61 Medium clayey _SAND Building Pad 7 Olive-brown silty to 81 Medium clayey SAND Building Pad 8 Olive-brown to light 84 Medium brown clayey silty SAND Building Pad 9 Olive-brown to light 77 Medium brown _clayey _silty _SAND Building Pad 10 Olive-brown clayey to 62 Medium silty SAND * Based on the 1997 edition of the Uniform Building Code (UBC), Table 18-I-B. C-i 971009-025 APPENDIX C (Continued) Maximum Density Tests: The maximum dry density and optimum moisture content of typical soils were determined in accordance with ASTM Test Method D1557. The results of these tests are presented in the table below: Sample Number Sample Description Maximum Dry Density (pcf) Optimum Moisture Content (%) 2 Brown sandy silty CLAY 122.5 11.5 4 Olive-brown clayey SAND 120.5 12.5 8 Gray-brown to olive-brown clayey silty fine SAND 117.5 14.0 9 Light olive-gray clayey silty SAND 118.0 15.0 10 Light brown clayey very fine SAND 112.5 16.0 11 Brown clayey SAND (fill mix) 120.0 13.0 14 Light olive-brown silty clayey SAND 124.0 12.0 16 Light gray fine SAND 117.0 14.0 17 Light yellow-brown clayey silty SAND 114.0 14.5 18 Light olive brown silty clayey SAND 113.0 16.0 19 Yellow brown clayey silty SAND 118.0 15.0 20 Pale olive to light brown clayey silty SAND 116.0 14.0 21 Pale olive to light brown clayey silty SAND 118.0 13.0 22 Pale olive to gray brown silty SAND 124.0 12.0 23 Pale olive to gray-brown clayey silty SAND 119.0 13.0 C-2 971009-025 APPENDIX C (Continued) Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical methods. The test results are presented in the table below: Sample Location Sample Description Sulfate Content Sulfate Exposure* (%) Building Pad 1 Olive-gray silty SAND 0.075 . Negligible Building Pad 2 Light brown silty SAND 0.10 Moderate Building Pad 3 Olive-brown silty to clayey 0.063 Negligible SAND Building Pad 4 Olive-brown silty to clayey 0.063 Negligible SAND Building Pad 5 Olive-brown silty to clayey 0.10 Moderate SAND Building Pad 6 Olive-brown silty to clayey 0.045 Negligible SAND Building Pad 7 Olive-brown silty to clayey 0.025 Negligible SAND Building Pad 8 Olive-brown to light brown 0.075 Negligible _silty _SAND clayey • Building Pad 9 Olive-brown to light brown 0.030 Negligible clayey silty SAND Building Pad 10 Olive-brown to light brown 0.045 . Negligible clayey _silty _SAND * Based on the 1997 edition of the Uniform Building Code (UBC), Table 19-A-4 (ICBO, 1997). C-3 Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page lof6 I LEIGHTON AND ASSOCIATES, INC. GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH GRADING 1.0 General 1.1 Intent: These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnièal report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the 'recommendations in the geotechnical report(s). I 1.2 The Geotechnical Consultant of Record: Prior to commencement of work, the owner shall employ the Geotechnical Consultant of Record (Geotechnical Consultant). The Geotechnical Consultants shall be responsible for reviewing the approved geotechnical I . report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencementof the grading. I Prior to commencement of grading, the Geotechnical Consultant shall review the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to perform the appropriate level of observation, mapping, and compaction testing. I I I. I. I I I I 3030.1094 I During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required. Subsurface areas to be geotechnically observed, mapped, elevations recorded, and/or tested include natural ground after it has been cleared for receiving fill but before fill.is placed, bottoms of all "remedial removal" areas, all key bottoms, and benches made on sloping ground to receive fill. The Geotechnical Consultant shall observe the moisture-conditioningand processing of the subgrade and fill materials and perform relative compaction testing of fill to determine the attained level of compaction. The Geôtechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis. Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 2 of 6 I 1.3 The Earthwork Contractor: The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moisture-conditioning and processing of fill, and compacting fill. I The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for performing the grading in accordance with the plans and specifications. I The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of "spreads" of work and the estimated quantities of daily earthwork contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the Geotechnical I Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate observations and tests can be planned and accomplished. The Contractor shall not assume that the Geotechnical Consultant is aware I of all grading operations. The Contractor shall have the sole responsibility to provide adequate equipment and I . methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical I Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant I shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified. I 2.0 Preparation of Areas to be Filled I 2.1 Clearing and Grubbing: Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant. I The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic I materials (by volume). No fill lift shall contain more than 5 percent of organic matter. Nesting of the organic materials shall not be allowed. ' If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to êontinuingto work in that area. As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered I to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be allowed. I 30301094 I Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 3of6 2.2 Processing: Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be overexcavatedas specified in the following section. Scarification shall continue until soils are broken down and free of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction. 2.3 Overexcavation: In addition to removals and overexcavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be overexcavated to competent ground as evaluated by the Geotechnical Consultant during grading. 2.4 Benching: Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill. 2.5 Evaluation/Acceptance of Fill Areas: All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches. 3.0 Fill Material I 3.1 General: Material to be used as fill shall be essentially free of organic matter and other deleterious substancesevaluatedand accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such. as those with .. unacceptable gradation, high I expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or in ixed with other soils to achieve satisfactory fill material. ' 3.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical I Consultant. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction. I 3030.1094 I I I I I I I I I I I I Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 4of6 3.3 Import: If importing of fill material is required for grading, proposed import material shall meet the requirements of Section 3.1. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed. I 4.0 Fill Placement and Compaction 4.1 Fill Layers: Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The I Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughlyto attain relative uniformityof material-and moisture throughout. I 4.2 Fill Moisture Conditioning: Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. I Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557-91). 1 4.3 Compaction of Fill: After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density I . (ASTM Test Method D1557-91). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity. I 4.4 Compaction of Fill Slopes: In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing I satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of I .maximum density per ASTM Test Method Dl 557-91. 4.5 Compaction Testing: Field tests for- moisture and:relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests I shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be I inadequate selected to verify adequacy of compaction levels in areas that are judged to be prone to to faces the fill/bedrock benches). compaction (such as close slope and at I I I 3030.1094 I Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 5 of 6 4.6 Frequency of Compaction Testing: Tests shall betaken at intervals not exceeding 2 feet in I vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope I face and/or each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these I minimum standards are not met. 4.7 Compaction Test Locations: The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate I . with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 1 5 feet apart from potential test locations shall be provided. 5.0 Subdrain Installation Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the I . grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional su,bdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for I line and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys. 6.0 Excavation I Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only. The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant. 1 I I 1 3030.1094 I Leighton and Associates, Inc. GENERAL EARTHWORK AND GRADING SPECIFICATIONS Page 6of6 7.0 Trench Backfills 7.1 The Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench excavations. 7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to I foot over the top of the conduit and densified by jetting. Backfill shall be placed and densifiedto a minimum of 90 percent of maximum from 1 foot above the top of the( conduit to the surface. 7.3 The jetting of the bedding around the conduits shall be observed by the Geotechnical Consultant. 7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill. 7.5 Lift thickness of trench backfill, shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method. ( 3030.1094 CUT—OVER—FILL SLOPE OVERBUILD AND TRIM BACK /7 EXISTIN G GROUND ACE REMOVE DESIGN SLOPE - QMPcThD I UNSUITABLE - - MATERIAL - / BENCH BENCH HEIGHT -7 TYPICAL) 15' MIN. CUT FACE SHALL BE CONSTRUCTED PRIOR TO FILL PLACEMENT FOR SUBDRAINS SEE STANDARD DETAIL C PROJECTED PLANE- 1 TO 1 MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND FILL SLOPE ----------------------- PROJECTED PLANE - - - 1 TO 1 MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND -'_'- REMOVE EXISTING i--:-:-- UNSUITABLE GROUND SURFACE --:-±-: BENCH 'BENCH HEIG HT MATERIAL (4- TYPICAL) J 15' MIN. 2' MIN. LOWEST KEY BENCH DEPTH (KEY) ------------- FILL—OVER—CUT SLOPE cA: TILL EXISTING GROUND SURFACE I BENCH 'BENCH HEIGHT H (4' TYPICAL) - - 7MIN 15 MIN. LOWEST REMOVE ~2'M IN. BENCH UNSUITABLE KEY (KEY) MATERIAL DEPTH CUT FACE SHALL BE CONSTRUCTED PRIOR TO FILL PLACEMENT TO ASSURE ADEQUATE GEOLOGIC CONDITIONS 2' MIN KEY DEPTH BENCH BENCHING SHALL BE DONE WHEN SLOPE'S (KEY) ANGLE IS EQUAL TO OR GREATER THAN 5:1. MINIMUM BENCH HEIGHT SHALL BE 4 FEET AND MINIMUM FILL WIDTH SHALL BE 9 FEET. GENERAL EARTHWORK AND KEYING AND BENCHING GRADING SPECIFICATIONS . STANDARD DETAILS A LEIGHTON AND ASSOCIATES ISH GRADE SLOPE FACE -- , /' -ici COMP1D .FJLL 5 MI N ------------------------------------------------------ -~- ~~ X-m 41 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (VPPI7F WINJflRflW * OVERSIZE ROCK IS LARGER THAN 8 INCHES IN LARGEST DIMENSION. * EXCAVATE A TRENCH IN THE COMPACTED FILL DEEP ENOUGH TO BURY ALL THE ROCK. * BACKFILL WITH GRANULAR SOIL JETTED OR FLOODED IN PLACE TO FILL ALL THE VOIDS. * DO NOT BURY ROCK WITHIN 10 FEET OF FINISH GRADE. * WINDROW OF BURIED ROCK SHALL BE PARALLEL TO THE FINISHED SLOPE. —6" MAX - - - - GRANULAR MATERIAL TO BE'DETAIL DENSIFIED IN PLACE BY FLOODING OR JETTING. ------------ JETTED OR FLOODED GRANULAR MATERIAL TYPICAL PROFILE ALONG WINDROW OVERSIZE GENERAL EARTHWORK AND .. ., ROCK DISPOSAL GRADING SPECIFICATIONS STANDARD DETAILS B LEIGH rON AND ASSOCIATES \N EXISTING GROUND SURFACE - - -- - REMOVE BENCHINGY SUBDRAIN U MATERIAL NSUITABLE TRENCH SEE DETAIL BELOW 6" MIN. OVER / CALTRANS CLASS 2 PERMEABLE OR #2 ROCK (9FT"3/FT) WRAPPED) •". IN FILTER FABRIC /• FILTER FABRIC (MIRAFI 140N OR APPROVED EQUIVALENT)' 6' MIN. COVER 4" MIN. BEDDING \ t COLLECTOR PIPE SHALL BE MINIMUM 6" DIAMETER SCHEDULE 40 PVC PERFORATED PIPE, SEE STANDARD DETAIL D FOR PIPE SPECIFICATIONS DESIGN FINISH GRADE - 10' MIN. BACKFILL --:-:COMPACTED -------------------------------- ---------------------------------- FILTER FABRIC (MIRAFI 140N OR APPROVED EQUIVALENT) —CALTRANS CLASS 2 PERMEABLE OR #2 ROCK (9FT"3/FT) WRAPPED IN FILTER FABRIC H 20' MIN, MIN. PERFORATED NONPERFORATED 6"0 MIN. b 0 MIN. }-'IF GENERAL EARTHWORK AND .. .. CANYON SUBDRAINS GRADING SPECIFICATIONS STANDARD DETAILS C .. LE!GHTON AND ASSOCIATES 15' MIN. OUTLET PIPES A" r7i Kir)Kic)~DE-r)DA Tr DIDC t .:::I::I:::1::::::::::::-::f --____BACK CUT 100 MAX. D.C. HORIZONTALLY, 11 OR FLATTER 30 MAX O.C.VERTICALLY / I Iff - :::::::_:_::::::::::::::::::::::_:_ BENCH ----------------- --:-:-:-:2% MINI. -:-:-:-:-:-7 SEE SUBDRAIN TRENCH - DETAIL LOWEST SUBDRAIN SHOULD COMPACTED FILL BE SITUATED AS LOW AS - -:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-i-:-:-:-:-:-:-:-:-:-:- -- POSSIBLE TO ALLOW - ::::::::::::i:::::::::::::::::::::::::::::::::::::::::~: SUITABLE OUTLET :2% MIN f H KEY WIDTH AS NOTED ON GRADING PLANS 12" MIN. OVERLAP [KEY DEPTH (15' MIN.) FROM THE HOG 1 (2 MIN.) RING TIED EVERY 6 FEET T—CONNECTION FOR COLLECTOR PIPE TO OUTLET PIPE CALTRANS CLASS II PERMEABLE OR #2 ROCK (3 FT"3/FT) WRAPPED IN FILTER ..1J6MI FABRIC ft VOUThEIPIPE__ I' P PIPE ERFORATED /MIN. BEDDING PROVIDE POSITIVE SEAL AT THE JOINT FILTER FABRIC ENVELOPE (MIRAFI 140 OR APPROVED EQUIVALENT) SUBDRAIN TRENCH DETAIL SUBDRAIN INSTALLATION - subdrain collector pipe shall be installed with perforation down or, unless otherwise designated by the geotechnicol consultant. Outlet pipes shall be non—perforated pipe. The subdrain pipe shall have at least 8 perforations uniformly spaced per foot. Perforation shall be 1/4" to 1/2" if drill holes are used. All subdrain pipes shall have a gradient of at least 2% towards the outlet. SUBDRAIN PIPE - Subdrain pipe shall be ASTM D2751, SDR 23.5 or ASTM D1527, Schedule 40, or ASTM D3034, SDR 23.5, Schedule 40 Polyvinyl Chloride Plastic (PVC) pipe. All outlet pipe shall be placed in a trench no wide than twice the subdrain pipe. Pipe shall be in soil of SE >/=30 jetted or flooded in place except for the outside 5 feet which shall be native soil backfill. BUTTRESS OR GENERAL EARThWORK AND REPLACEMENT FILL GRADING SPECIFICATIONS I SUBDRAINS STANDARD DETAILS D LEIGHTON AND ASSOCIATES SOIL BACKFILL, COMPACTED TO 90 PERCENT RELATIVE COMPACTION BASED ON ASTM D1557 -:-:-:-:-:-:-:-:-:-:-:-:-:- ---------- RETAINING WALL WALL-_,,, r-i WALL WATERPROOFING OVERLAP FILTER FABRIC ENVELOPE PER ARCHITECT'S 0 • o• :-:-:---(MIRAFI 140N OR APPROVED SPECIFICATIONS I 0 o°I IEi-i EQUIVALENT)** 1 MIN. - : TO 11/2 CLEAN GRAVEL FINISH GRADE : 0 4 (MN.) DIAMETER PERFORATED / 0 ---PVC PIPE (SCHEDULE 40 OR / I • o0 0. EQUIVALENT) WITH PERFORATIONS 0 ORIENTED DOWN AS DEPICTED -COMPACTED FILL I 0 TO SUITABLE OUTLET I MINIMUM GRADIENT _______ 3 MIN. WALL FOOTING -t- COMPETENT BEDROCK DR MATERIAL AS EVALUATED BY THE GEOTECHNICAL CONSULTANT NOTE: UPON REVIEW BY THE GEOTECHNICAL CONSULTANT, COMPOSITE DRAINAGE PRODUCTS SUCH AS MIRADRAIN OR J-DRAIN MAY BE USED AS AN ALTERNATIVE TO GRAVEL OR CLASS 2 PERMEABLE MATERIAL. INSTALLATION SHOULD BE PERFORMED IN ACCORDANCE WITH MANUFACTURER'S SPECIFICATIONS. RETAINING WALL GENERAL EARTHWORK AND DRAINAGE DETAIL GRADING SPECIFICATIONS LEIGHTON AND ASSOCIATES