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HomeMy WebLinkAboutCDP 16-26; TABATA RANCH; UPDATED GEOTECHNICAL RECOMMENDATIONS; 2018-03-05CIE. lillrc 0 Construction Testing & Engineering, Inc. Inspection I Testing I Geotechnical I Environmental & Construction Engineering I Civil Engineering I Surveying August 26, 2016 (Revised March 5, 2018) CTE Project No. 10-13292G Tabata Family Trust C/O: WMC General Contractors, Inc. Attention: Mr. Bruce Wiegand 760 Garden View Ct., Suite 200 Encinitas, California 92024 Telephone: (760)803-2427 Via Email: bruce@wncommunities.com Subject: Update Geotechnical Recommendations for Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive Carlsbad California RECflVED MAR 21 2018 LAND DEVELOPMENT ENGINEERING References: At end of document Mr. Wiegand: In accordance with your request, Construction Testing & Engineering, Inc. (CTE) has completed a review of the previously prepared geotechnical reports and documentation for Lot 4 at the subject site, as referenced herein. We also visited the site on August 23, 2016 to confirm current conditions. Recommendations are based on prior site documentation referenced herein, new and/or updated regulatory requirements, review of current site conditions, and the scope of work we agreed to perform at this time. Based on the project improvement plans, the proposed construction is to consist of a two-story, light- framed, residential structure with conventional continuous and/or spread footings. Associated utilities, flatwork, paving, landscaping, and other minor improvements may also be constructed. CTE has found the recommendations in the referenced geotechnical documents to be in compliance with common geotechnical engineering practices and should be considered valid unless revised herein. However, CTE reserves the right to further modify recommendations and/or provide additional recommendations based on the actual conditions encountered at the site during earthwork and/or construction. Updated seismic loading parameters are also provided herein in accordance with the requirements of the current California Building Code. Updated standard grading recommendations (Appendix D) are also attached herewith, though additional grading is anticipated to be relatively minor. 1441 Montiel Road, Suite 115 1 Escondido, CA 92026 I Ph(760)7464955 f Fax(760)746-9806 I www.cte-inc.net Update Geotechnical Recommendations Page 2 Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive, Carlsbad California August 26, 2016 (Revised March 5, 2018) CTE Job No. 10-13292G Based on our review, the existing building pad at the subject site was previously graded in accordance with the referenced reports. It appears that site conditions have remained generally consistent to those described in the original and as-graded reports. Significant changes, distress, and/or erosion in the building pad areas was not noted. Therefore, based on this information and on reference review, we provide the following update recommendations. 1.0 SITE PREPARATION Based on the limited preliminary plans and information provided, as well as our understanding of the proposed development, the following remedial recommendations are believed to be appropriate at this time. All proposed building footprints and other distress sensitive improvement areas should be cleared of existing vegetation, construction debris, stockpiled, deleterious, and other loose materials. Objectionable materials, such as construction debris and vegetation, not suitable for structural backfill should be properly disposed of offsite. Following removal of loose and unsuitable soils and approval from the geotechnical representative, exposed areas should be scarified a minimum of eight inches, moisture conditioned, and compacted to a minimum relative compaction of 90 percent, as evaluated by ASTM D 1557, at a minimum two percent above optimum. Fill and backfill should be compacted to a minimum relative compaction of 90 percent as evaluated by ASTM D 1557, at a minimum two percent above optimum. Minimum relative compaction of 95 percent (per ASTM D- 1557) should be conducted for the minimum top 12 inches of subgrade beneath proposed pavement and drive areas, and for all/any aggregate base. The optimum lift thickness for backfill soil will depend on the type of compaction equipment used. Generally, fill soil should be placed in uniform lifts not exceeding eight inches in loose thickness. Fill placement and compaction should be performed in overall conformance with the geotechnical recommendations and project specifications in conformance with local ordinances. A CTE geotechnical representative should observe and test the bottom of overexcavation and compaction of soils within the proposed building footprints and other distress sensitive improvement areas. 2.0 SEISMIC LOADING PARAMETERS I The seismic ground motion values listed in the table below were derived in accordance with the ASCE 7-10 Standard that is incorporated into the California Building Code, 2016. This was accomplished by establishing the Site Class based on the soil properties at the site, and then calculating the site I coefficients and parameters using the United States Geological Survey Seismic Design Maps application. These values are intended for the design of structures to resist the effects of earthquake ground motions. \\ESC_SERVER\Projects\10-13000 to 10-13999 Projects\10-13292G\Ltr_Updat Recommendations Lot 4 - 10-13292G.doc Update Geotechnical Recommendations Page 3 Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive, Carlsbad California August 26, 2016 (Revised March 5, 2018) CTE Job No. 10-13292G TABLE 2.0 SEISMIC GROUND MOTION VALUES 2013 CBC AND ASCE 7-10 PARAMETER VALUE CBC REFERENCE (2016) Site Class D ASCE 7, Table 20.3-1 Mapped Spect?al Response Acceleration Parameter, S5 1.108g Figure 1613.3.1 (1) Mapped Spectral Response Acceleration Parameter, S 0.426g Figure 1613.3.1 (2) Seismic Coefficient, Fa 1.057 Table 1613.3.3 (1) Seismic Coefficient, F 1.574 Table 1613.3.3 (2) MCE Spectral Response Acceleration Parameter, 5MS 1.171g Section 1613.3.3 MCE Spectral Response Acceleration Parameter, SMI 0.6719 Section 1613.3.3 Design Spectral Response Acceleration, Parameter S0 0.780g Section 1613.3.4 Design Spectral Response Acceleration, Parameter S01 0.447g Section 16 13.3.4 Peak Ground Acceleration PGAM 0.466g ASCE 7, Section 11.8.3 3.0 FOUNDATION WALL AND SLOPE SETBACK I Footings for structures should be designed such that the horizontal distance from the face of adjacent descending slopes to the outer edge of the footing is a minimum of 10 feet. In addition, foundations should bear beneath an imaginary 1:1 plane extended up from the nearest bottom edge of adjacent I parallel trenches or excavations located within 10 feet. Deepening of affected footings should be a suitable means of attaining the prescribed setbacks. In addition, footings located adjacent to retaining walls should bear beneath an imaginary 1:1 plane extending upward from the base of the wall retaining soil in order to minimize additional surcharge load to the wall itself. 4.0 WALLS BELOW GRADE If retaining walls are to be constructed in association with the proposed development, the following parameters are anticipated to be applicable. For the design of subterranean walls where the surface of I the backfill is level, it may be assumed that the soils will exert a lateral pressure equal to that developed by a fluid with a density of 35 pcf. The active pressure should be used for walls free to yield at the top at least 0.2 percent of the wall height. For walls restrained so that such movement is not permitted, an I equivalent fluid pressure of 60 pcf should be used, based on at-rest soil conditions. The recommended \\ESC_SERVER\Projects\10-13000 to 10-13999 Projects\10.13292G\Ltr_Update Recommendations Lot 4- 10-132920.doc Update Geotechnical Recommendations Page 4 Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive, Carlsbad California August 26, 2016 (Revised March 5, 2018) CTE Job No. 10-13292G I equivalent fluid pressures should be increased according to Table 4.0 below for walls retaining soils inclined at 2:1 (horizontal: vertical). Walls below the water level are not anticipated for the subject site. I In addition to the recommended earth pressure, subterranean structure walls adjacent to traffic loads should be designed to resist a uniform lateral pressure of 100 psf. This is the result of an assumed 300- psf surcharge behind the walls due to normal street traffic. If the traffic is kept back at least 10 feet or a I distance equal to the retained soil height from the subject walls, whichever is less, the traffic surcharge may be neglected. The project architect or structural engineer should determine the necessity of waterproofing retaining walls to reduce moisture infiltration. Retaining wall backfill located within a 45-degree wedge extending up from the heel of the wall should consist of soil having an Expansion Index of 30 or less (ASTM D 4829) with less than 30 percent passing the No. 200 sieve. The upper 12 to 18 inches of wall backfill should consist of lower permeability soils, in order to reduce surface water infiltration behind walls. The project structural engineer and/or architect should detail proper wall backdrains, including gravel drain zones, fills, filter fabric and perforated drain pipes. TABLE 4.0 EQUIVALENT FLUID UNIT WEIGHTS (pounds per cubic foot) SLOPE BACKFILL WALL TYPE LEVEL BACKFILL 2:1 (HORIZONTAL: VERTICAL) CANTILEVER WALL (YIELDING) 35 45 RESTRAINED WALL 60 80 Lateral pressures on cantilever retaining walls (yielding walls) due to earthquake motions may be calculated based on work by Seed and Whitman (1970). The total lateral thrust against a properly drained and backfilled cantilever retaining wall above the groundwater level can be expressed as: PAE = PA + APAE For non-yielding (or "restrained") walls, the total lateral thrust may be similarly calculated based on work by Wood (1973): PKE = PK + AP1 Where PA = Static Active Thrust (given previously Table 4.0) PK = Static Restrained Wall Thrust (given previously Table 4.0) APAE = Dynamic Active Thrust Increment = (3/8) kh yH2 APKE = Dynamic Restrained Thrust Increment = kh yH2 \\ESC_SERVER\Projects\10-13000 to 10-13999 Projects\10-1 3292G\Ltr_Update Recommendations Lot 4 - 10-13292G.doc Update Geotechnical Recommendations Page 5 Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive, Carlsbad California August 26, 2016 (Revised March 5, 2018) CTE Job No. 10-13292G kh = 2/3 Peak Ground Acceleration = 2/3 (PGAM) H = Total Height of the Wall = Total Unit Weight of Soil z 135 pounds per cubic foot The increment of dynamic thrust in both cases should be distributed triangularly with a line of action located at H/3 above the bottom of the wall (SEAOC, 2013). These values assume non-expansive backfill and free-draining conditions. Measures should be taken to prevent moisture buildup behind all retaining walls. Drainage measures should include free-draining backfill materials and sloped, perforated drains, as designed and detailed by the wall engineer or architect of record. These drains should discharge to an appropriate off-site location. Any necessary waterproofing should be as specified by the project architect. 5.0 LIMITATIONS As indicated, the updated recommendations herein are based on our evaluation performed to date and could require modification as project improvement plans further progress and/or based on conditions encountered during construction. The field evaluation and geotechnical analysis referenced in our geotechnical documents was conducted according to current engineering practice and the standard of care exercised by reputable Geotechnical Consultants performing similar tasks in this area. No other warranty, expressed or implied, is made regarding the conclusions, recommendations and opinions expressed. Variations may exist and conditions not observed or described may be encountered during construction. Our conclusions and recommendations are based on an analysis of the observed conditions. If conditions different from those described are encountered, our office should be notified and additional recommendations, if required, will be provided upon request. We appreciate the opportunity to be of service on this project. Should you have questions, please contact the undersigned at your convenience. Respectfully submitted, CONSTRUCTION TESTING & ENGINEERING, INC. ESSI T. Dan T. Math, GE #2665 0 Rodney J. Jones, RC #84232 EXP, 9/30/17 ) p 12 Rodne Principal Engineer * Project Engineer oi RJJ/JFLIDTM:nri Appendix D Standard Grading Recommendations \\ESC_SERVER\Projects\10-13000 to 10-13999 Projects\10-13292G\Ltr_Update Recommendations Lot 4- 10-13292G.doc Update Geotechnical Recommendations Page 6 Proposed Tabata Ranch Subdivision Lot-4 Lemon Leaf Drive, Carlsbad California August 26, 2016 (Revised March 5, 2018) CTE Job No. 10-13292G I References: Interim As-Greaded Geotechnical Report Proposed Tabata Ranch Subdivision Lemon Leaf Drive I Carlsbad, California CTE Project No. 10-12101G, dated August 2, 2015 I Lot 3 Subdrain Recommendations and Elimination of Retaining Wall Proposed Tabata Ranch Subdivision Lemon Leaf Drive I Carlsbad California CTE Pro ect No. 10-12101G, dated July 14, 2014 I Transfer of Geotechnical Responsibility Letter Proposed Tabata Ranch Subdivision Lemon Leaf Drive I Carlsbad, California CTE Project No. 10-12101G, dated July 1, 2014 I Geotechnical and Update Report and Grading Plan Review Proposed Tabata Ranch Subdivision Lemon Leaf Drive, Carlsbad, California I Vinje & Middleton Engineering Job # 01-364-P, dated August 2, 2006 Preliminary Geotechnical Investigation I Proposed 4-Lot Subdivision, Tabata Ranch Off Camino De Las Ondas and Lonicera Street, Carlsbad, California Vinje & Middleton Engineering Job # 01-364-P, dated October 24, 2001 I \\ESC_SERVER\Projects\10-13000 to 10-13999 Projects\10-13292G\Ltr_Update Recommendations Lot 4- 10-13292G.doc APPENDIX D STANDARD SPECIFICATIONS FOR GRADING Appendix Page D-i Standard Specifications for Grading Section 1 - General Construction Testing & Engineering, Inc. presents the following standard recommendations for grading and other associated operations on construction projects. These guidelines should be considered a portion of the project specifications. Recommendations contained in the body of the previously presented soils report shall supersede the recommendations and or requirements as specified herein. The project geotechnical consultant shall interpret disputes arising out of interpretation of the recommendations contained in the soils report or specifications contained herein. I Section 2 - Responsibilities of Project Personnel The geotechnical consultant should provide observation and testing services sufficient to general I conformance with project specifications and standard grading practices. The geotechnical consultant should report any deviations to the client or his authorized representative. I 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 I 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 is 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, earth work in accordance with the project plans, specifications and controlling agency requirements. Section 3 - Preconstruction Meeting A preconstruction site meeting should be arranged by the owner and/or client and should include the grading contractor, design engineer, geotechnical consultant, owner's representative and representatives of the appropriate governing authorities. Section 4 - Site Preparation The client or contractor should obtain the required approvals from 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. STANDARD SPECIFICATIONS OF GRADING Page 1 of 26 I Appendix D Page D-2 I Standard Specifications for Grading - Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods, stumps, trees, root of trees and otherwise deleterious natural materials from the areas to be I graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas. I Demolition should include removal of buildings, structures, foundations, reservoirs, utilities (including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts, I tunnels, etc.) and other man-made surface and subsurface improvements from the areas to be graded. Demolition of utilities should include proper capping and/or rerouting pipelines at the project perimeter and cutoff and capping of wells in accordance with the requirements of the I governing authorities and the recommendations of the geotechnical consultant at the time of demolition. I Trees, plants or man-made improvements not planned to be removed or demolished should be protected by the contractor from damage or injury. I 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 I performed under the observation of the geotechnical consultant. Section 5 - Site Protection I Protection of the site during the period of grading should be the responsibility of the contractor. S Unless other provisions are made in writing and agreed upon among the concerned parties, I 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 I complete as identified by the geotechnical consultant, the client and the regulating agencies. - Precautions should be taken during the performance of site clearing, excavations and grading to I protect :he 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 cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. Rain related damage should be considered to include, but may not be limited to, erosion, silting, I saturation, swelling, structural distress and other adverse conditions as determined by the geotechnical consultant. Soil adversely affected should be classified as unsuitable materials and should be subject to overexcavation and replacement with compacted fill or other remedial I grading as recommended by the geotechnical consultant. I STANDARD SPECIFICATIONS OF GRADING Page 2 of 26 I Appendix Page D-3 Standard Specifications for Grading 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 requirements that are more restrictive by the regulating agencies. The contractor should provide during periods of extensive rainfall plastic sheeting to prevent unprotected slopes from becoming saturated and unstable. When deemed appropriate by the geotechnical consultant or governing agencies the contractor shall install checkdams, desilting basins, sand bags or other drainage control measures. In relatively level areas and/or slope areas, where saturated soil and/or erosion gullies exist to depths of greater than 1.0 foot; they should be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where affected materials exist to depths of 1.0 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. If field conditions dictate, the geotechnical consultant may recommend other slope repair procedures. Section 6 - Excavations 6.1 Unsuitable Materials Materials that 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. Material identified by the geotechnical consultant as unsatisfactory due to its moisture I conditions should be overexcavated; moisture conditioned as needed, to a uniform at or above optimum moisture condition before placement as compacted fill. If during the course of grading adverse geotechnical conditions are exposed which were not anticipated in the preliminary soil report as determined by the geotechnical consultant additional exploration, analysis, and treatment of these problems may be recommended. STANDARD SPECIFICATIONS OF GRADING Page 3 of 26 Appendix D Page D-4 Standard Specifications for Grading 6.2 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). The geotechnical consultant should observe cut slope excavation and if these excavations expose loose cohesionless, significantly fractured or otherwise unsuitable material, the materials should be overexcavated and replaced with a compacted stabilization fill. If encountered specific cross section details should be obtained from the Geotechnical Consultant. When extensive cut slopes are excavated or these cut slopes are made in the direction of the prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided at the top of the slope. I;'l P1 Arpnc All lot pad areas, including side yard terrace containing both cut and fill materials, transitions, located less than 3 feet deep should be overexcavated to a depth of 3 feet and replaced with a uniform compacted fill blanket of 3 feet. Actual depth of overexcavation may vary and should be delineated by the geotechnical consultant during grading, especially where deep or drastic transitions are present. 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 drainage swale and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-slopes of 2 percent or greater is recommended. U Section 7 - Compacted Fill All fill materials should have fill quality, placement, conditioning and compaction as specified below or as approved by the geotechnical consultant. 7.1 Fill Material Quality Excavated on-site or import 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. All import materials anticipated for use on-site should be sampled tested and approved prior to and placement is in conformance with the requirements outlined. STANDARD SPECIFICATIONS OF GRADING Page 4 of 26 Appendix D Page D-5 Standard Specifications for Grading Rocks 12 inches in maximum and smaller may be utilized within compacted fill provided sufficient fill material is placed and thoroughly compacted over and around all rock to effectively fill rock voids. The amount of rock should not exceed 40 percent by dry weight passing the 3/4-inch sieve. The geotechnical consultant may vary those requirements as field conditions dictate. Where rocks greater than 12 inches but less than four feet of maximum dimension are generated during grading, or otherwise desired to be placed within an engineered fill, special handling in accordance with the recommendations below. Rocks greater than four feet should be broken down or disposed off-site. 7.2 Placement of Fill Prior to placement of fill material, the geotechnical consultant should observe and approve the area to receive fill. After observation and approval, the exposed ground surface should be scarified to a depth of 6 to 8 inches. The scarified material should be conditioned (i.e. moisture added or air dried by continued discing) to achieve a moisture content at or slightly above optimum moisture conditions and compacted to a minimum of 90 percent of the maximum density or as otherwise recommended in the soils report or by appropriate government agencies. I Compacted fill should then be placed in thin horizontal lifts not exceeding eight inches in loose thickness prior to compaction. Each lift should be moisture conditioned as needed, thoroughly blended to achieve a consistent moisture content at or slightly above optimum l and 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 I watering apparatus on the job site to handle the amount of fill being placed in consideration of moisture retention properties of the materials and weather conditions. I 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 six-foot wide benches I and a minimum of four 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 after keying and benching until the geotechnical consultant has reviewed the area. Material generated by the benching operation should be moved sufficiently away from STANDARD SPECIFICATIONS OF GRADING Page 5 of 26 Appendix D Page D-6 Standard Specifications for Grading the bench area to allow for the recommended review of the horizontal bench prior to placement of fill. 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. Prior to placement of additional compacted fill following an overnight or other grading delay, the exposed surface or previously compacted fill should be processed by scarification, moisture conditioning as needed to at or slightly above optimum moisture content, thoroughly blended and recompacted to a minimum of 90 percent of laboratory maximum dry density. Where unsuitable materials exist to depths of greater than one foot, the unsuitable materials should be over-excavated. Following a period of flooding, rainfall or overwatering by other means, no additional fill I should be placed until damage assessments have been made and remedial grading performed as described herein. Rocks 12 inch in maximum dimension and smaller may be utilized in the compacted fill provided the fill is placed and thoroughly compacted over and around all rock. No I oversize material should be used within 3 feet of finished pad grade and within 1 foot of other compacted fill areas. Rocks 12 inches up to four feet maximum dimension should be placed below the upper 10 feet of any fill and should not be closer than 15 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 or I deep utilities are proposed. 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 I over and around all windrowed rock, such that voids are filled. Windrows of oversized material should be staggered so those successive strata of oversized material are not in I 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 the time of placement. I STANDARD SPECIFICATIONS OF GRADING Page 6 of 26 I Appendix D Page D-7 Standard Specifications for Grading The contractor should assist the geotechnical consultant and/or his representative by digging test pits for removal determinations and/or for testing compacted fill. The contractor should provide this work at no additional cost to the owner or contractor's client. Fill should be tested by the geotechnical consultant for compliance with the recommended relative compaction and moisture conditions. Field density testing should conform to ASTM Method of Test D 1556-00, D 2922-04. Tests should be conducted at a minimum of approximately two vertical feet or approximately 1,000 to 2,000 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. 7.3 Fill Slopes Unless otherwise recommended by the geotechnical consultant and approved by the regulating agencies, permanent fill slopes should not be steeper than 2:1 (horizontal: vertical). Except as specifically recommended in these grading guidelines compacted fill slopes should be over-built two to five feet 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 Dverbuilding 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. At the discretion of the geotechnical consultant, slope face compaction may be attempted by conventional construction procedures including backrolling. The procedure must create a firmly compacted material throughout the entire depth of the slope face to the surface of the previously compacted firm fill intercore. During grading operations, 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 established 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 STANDARD SPECIFICATIONS OF GRADING Page 7 of 26 I Appendix D Page D-8 Standard Specifications for Grading exceeding four feet in vertical slope height or the capability of available equipment, whichever is less, fill slopes should be thoroughly dozer trackrolled. For pad areas above fill slopes, positive drainage should be established away from the top-of-slope. This may be accomplished using a berm and pad gradient of at least two percent. I Section 8 - Trench Backfill Utility and/or other excavation of trench backfill should, unless otherwise recommended, be I compacted by mechanical means. Unless otherwise recommended, the degree of compaction should be a minimum of 90 percent of the laboratory maximum density. I Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two feet deep may be backfilled with sand and consolidated by jetting, flooding or by mechanical I 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 backfill operations during I construction. If utility contractors indicate that it is undesirable to use compaction equipment in close I proximity to a buried conduit, the contractor may elect the utilization of light weight mechanical compaction equipment and/or shading of the conduit with clean, granular material, which should I 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 of 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. Section 9 - Drainage Where deemed appropriate by the geotechnical consultant, canyon subdrain systems should be installed in accordance with CTE's recommendations during grading. Typical subdrains for compacted fill buttresses, slope stabilization or sidehill masses, should be installed in accordance with the specifications. STANDARD SPECIFICATIONS OF GRADING Page 8 of 26 Appendix D Page D-9 I Standard Specifications for Grading Roof, pad and slope drainage should be directed away from slopes and areas of structures to I suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, and concrete swales). For drainage in extensively landscaped areas near structures, (i.e., within four feet) a minimum ' of 5 percent gradient away from the structure should be maintained. Pad drainage of at least 2 percent should be maintained over the remainder of the site. I 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 could be I detrimental to slope stability and foundation performance. Section 10 - Slope Maintenance 10.1 - Landscape Plants To enhance surficial slope stability, slope planting should be accomplished at the I completion of grading. Slope planting should consist of deep-rooting vegetation requiring little watering. Plants native to the southern California area and plants relative to native plants are generally desirable. Plants native to other semi-arid and and areas I may also be appropriate. A Landscape Architect should be the best party to consult regarding actual types of plants and planting configuration. 1 10.2 - 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 I irrigation systems, provisions should be made for interrupting normal irrigation during periods of rainfall. 10.3 - Repair 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 prior to landscape planting. I 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. I If slope failures occur as a result of exposure to period of heavy rainfall, the failure areas and currently unaffected areas should be covered with plastic sheeting to protect against additional saturation. STANDARD SPECIFICATIONS OF GRADING Page 9 of 26 I Appendix D Page D- 10 Standard Specifications for Grading In the accompanying Standard Details, appropriate repair procedures are illustrated for superficial slope failures (i.e., occurring typically within the outer one foot to three feet of a slope face). STANDARD SPECIFICATIONS OF GRADING Page 10 of 26 BENCHING FILL OVER NATURAL SURFACE OF FIRM EARTH MATERIAL FILL SLOPE ;MIN 2%MIN ol 10, LJ TYPICAL 15' MIN. (INCLINED 2% MIN. INTO SLOPE) BENCHING FILL OVER CUT SURFACE OF FIRM EARTH MATERIAL FINISH FILL SLOPE FINISH CUT SLOPE je~2% MIN 10, TYPICAL 15' MIN OR STABILITY EQUIVALENT PER SOIL ENGINEERING (INCLINED 2% MIN. INTO SLOPE) NOT TO SCALE BENCHING FOR COMPACTED FILL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 11 of 26 TOE OF SLOPE SHOWN ON GRADING PLAN FILL - - 00, ------- I I' / MINIMUM _/ - 15 MINIMUM BASE KEY WIDTH DOWNSLOPE KEY DEPTH TYPICAL BENCH HEIGHT PROVIDE BACKDRAIN AS REQUIRED PER RECOMMENDATIONS OF SOILS ENGINEER DURING GRADING WHERE NATURAL SLOPE GRADIENT IS 5:1 OR LESS, BENCHING IS NOT NECESSARY. FILL IS NOT TO BE PLACED ON COMPRESSIBLE OR UNSUITABLE MATERIAL. NOT TO SCALE FILL SLOPE ABOVE NATURAL GROUND DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 12 of 26 10' TYPICAL BENCH WIDTH VARIES COMPETENT EARTH MATERIAL REMOVE ALL TOPSOIL, COLLUVIUM, AND CREEP MATERIAL FROM TRANSITION CUT/FILL CONTACT SHOWN ON GRADING PLAN FILL cn Z CUT/FILL CONTACT SHOWN - C ON "AS-BUILT" C C0 o0'_ TYPICAL C,) 1ps p) C•) - NATURALCD _____________ o TOPOGRAPHY" 2% MIN 10 10' TYPICAL 15' MINIMUM C) Q5 CUT SLOPE* BEDROCK OR APPROVED m FOUNDATION MATERIAL 0 C, C Z *NOTE: CUT SLOPE PORTION SHOULD BE C) MADE PRIOR TO PLACEMENT OF FILL NOT TO SCALE FILL SLOPE ABOVE CUT SLOPE DETAIL j- SURFACE OF / COMPETENT ------------------ C MATERIAL OMPACTED FILL \\ TYPICAL BENCHING REMOVE UNSUITABLE MATERIAL SEE DETAIL BELOW INCLINE TOWARD DRAIN AT 2% GRADIENT MINIMUM DETAIL ------------- MINIMUM 9 FT PER LINEAR FOOT MINIMUM 4" DIAMETER APPROVED OF APPROVED FILTER MATERIAL PERFORATED PIPE (PERFORATIONS DOWN) 6" FILTER MATERIAL BEDDING 14" MINIMUM CALTRANS CLASS 2 PERMEABLE MATERIAL APPROVED PIPE TO BE SCHEDULE 40 FILTER MATERIAL TO MEET FOLLOWING POLY-VINYL-CHLORIDE (P.V.C.) OR SPECIFICATION OR APPROVED EQUAL: APPROVED EQUAL. MINIMUM CRUSH SIEVE SIZE PERCENTAGE PASSING STRENGTH 1000 psi 1 100 PIPE DIAMETER TO MEET THE FOLLOWING CRITERIA, SUBJECT TO 90-100 FIELD REVIEW BASED ON ACTUAL GEOTECHNICAL CONDITIONS 40-100 ENCOUNTERED DURING GRADING NO. 4 25-40 LENGTH OF RUN PIPE DIAMETER NO.8 18-33 INITIAL 500' 4" NO. 30 5-15 500' TO 1500' 6" NO. 50 0-7 1500' 8" NO. 200 0-3 NOT TO SCALE TYPICAL CANYON SUBDRAIN DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 14 of 26 CANYON SUBDRAIN DETAILS SURFACE OF COMPETENT f MATERIAL ----------------- COMPACTED FILL TYPICAL BENCHING REMOVE UNSUITABLE MATERIAL SEE DETAILS BELOW INCLINE TOWARD DRAIN AT 2% GRADIENT MINIMUM TRENCH DETAILS 6" MINIMUM OVERLAP MINIMUM 9 FT PER LINEAR FOOT OPTIONAL V-DITCH DETAIL OR APPROVED EQUAL - - OF APPROVED DRAIN MATERIAL MIRAFI 140N FABRIC MIRAFI 140N FABRIC OR APPROVED EQUAL 6" MINIMUM OVERLAP L2j. APPROVED PIPE TO BE 24" SCHEDULE 40 7 POLY- 01 (P.V.C.) 0 MINIMUM OR APPROVED EQUAL. MINIMUM CRUSH STRENGTH MIMtM9 P PER LINEAR FOOT 1000 PSI. MINIMUM \ OF APPROVED DRAIN MATERIAL 600 TO 90° DRAIN MATERIAL TO MEET FOLLOWING PIPE DIAMETER TO MEET THE SPECIFICATION OR APPROVED EQUAL: FOLLOWING CRITERIA, SUBJECT TO FIELD REVIEW BASED ON ACTUAL SIEVE SIZE PERCENTAGE PASSING GEOTECHNICAL CONDITIONS ENCOUNTERED DURING GRADING 88-100 LENGTH OF RUN PIPE DIAMETER 1" 5-40 INITIAL 500 4" 3/4 0-17 500' TO 1500' 6" 0-7 1500' 8" NO. 200 0-3 NOT TO SCALE GEOFABRIC SUBDRAIN STANDARD SPECIFICATIONS FOR GRADING Page 15 of 26 FRONT VIEW CONCRETE CUT-OFF WALL SUBDRAIN PIPE 6" Min. -•-. - 6" Mm. 24 'in' . -I 6" Mm. SIDE VIEW -112 Mm. F- CONCRETE ,- - - - CUT-OFF WALL J 6" Mm. SOILD SUBDRAIN PIPE b. PERFORATED SUBDRAIN PIPE NOT TO SCALE RECOMMENDED SUBDRAIN CUT-OFF WALL STANDARD SPECIFICATIONS FOR GRADING Page 16 of 26 FRONT VIEW ! _• - , S S S S S S , 24" Mm. S S S S S S S S I S S • 5 24" Min.- SUBDRAIN OUTLET PIPE (MINIMUM 4" DIAMETER) SIDE VIEW ALL BACKFILL SHOULD BE COMPACTED IN CONFORMANCE WITH PROJECT SPECIFICATIONS. COMPACTION EFFORT SHOULD NOT DAMAGE STRUCTURE 6" CONCRETE HEADWALL - 4" \ " S Mm NOTE: HEADWALL SHOULD OUTLET AT TOE OF SLOPE OR INTO CONTROLLED SURFACE DRAINAGE DEVICE ALL DISCHARGE SHOULD BE CONTROLLED THIS DETAIL IS MINIMUM DESIGN AND MAY BE MODIFIED DEPENDING UPON ENCOUNTERED CONDITIONS AND LOCAL REQUIREMENTS NOT TO SCALE TYPICAL SUBDRAIN OUTLET HEADWALL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 17 of 26 4" DIAMETER PERFORATED PIPE BACKDRAIN 4" DIAMETER NON-PERFORATED PIPE LATERAL DRAIN SLOPE PER PLAN —s. 15' MINIMUM FILTER MATERIAL ENCHING i/V H/2 AN ADDITIONAL BACKDRAIN AT MID-SLOPE WILL BE REQUIRED FOR SLOPE IN EXCESS OF 40 FEET HIGH. KEY-DIMENSION PER SOILS ENGINEER (GENERALLY 1/2 SLOPE HEIGHT, 15' MINIMUM) DIMENSIONS ARE MINIMUM RECOMMENDED NOT TO SCALE TYPICAL SLOPE STABILIZATION FILL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 18 of 26 4" DIAMETER PERFORATED PIPE BACKDRAIN 4' DIAMETER NON-PERFORATED PIPE LATERAL DRAIN 15' MINIMUM SLOPE PER PLAN 2.0% FILTER MATERIAL BENCHING 4±HI H/2 1 2' ADDITIONAL BACKDRAIN AT MID-SLOPE WILL BE REQUIRED FOR SLOPE IN EXCESS OF 40 FEET HIGH. KEY-DIMENSION PER SOILS ENGINEER DIMENSIONS ARE MINIMUM RECOMMENDED NOT TO SCALE TYPICAL BUTTRESS FILL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 19 of 26 FINAL LIMIT OF DAYLIGHT EXCAVATION LINE FINISH PAD OVEREXCAVATE 3' AND REPLACE WITH COMPACTED FILL OVEREXCAVATE 20' MA)(IMUM SNAVAMAVAVAM MAN COMPETENT BEDROCK 2% MIN 2' MINIMUM \\ 'L TYPICAL BENCHING OVERBURDEN LOCATION OF BACKDRAIN AND (CREEP-PRONE) \ OUTLETS PER SOILS ENGINEER \ AND/OR ENGINEERING GEOLOGIST \ DURING GRADING. MINIMUM 2% \ FLOW GRADIENT TO DISCHARGE LOCATION. EQUIPMENT WIDTH (MINIMUM 15') NOT TO SCALE DAYLIGHT SHEAR KEY DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 20 of 26 PROPOSED GRADING liz - 15 1 - COMPACTED FILL 1.5 _ nw,1 PROVIDE BACKDRAIN, PER BACKDRAIN DETAIL. AN ADDITIONAL BACKDRAIN AT MID-SLOPE WILL BE REQUIRED FOR BACK BASE WIDTH 'W' DETERMINED SLOPES IN EXCESS OF BY SOILS ENGINEER 40 FEET HIGH. LOCATIONS OF BACKDRAINS AND OUTLETS PER SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST DURING GRADING. MINIMUM 2% FLOW GRADIENT TO DISCHARGE LOCATION. NOT TO SCALE TYPICAL SHEAR KEY DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 21 of 26 FINISH SURFACE SLOPE 3 FT MINIMUM PER LINEAR FOOT APPROVED FILTER ROCK* CONCRETE COLLAR PLACED NEAT COMPACTED FILL A 4" MINIMUM DIAMETER SOLID OUTLET PIPE SPACED PER SOIL ENGINEER REQUIREMENTS DURING GRADING TYPICAL BENCHING - 4" MINIMUM APPROVED PERFORATED PIPE** (PERFORATIONS DOWN) MINIMUM 2% GRADIENT TO OUTLET BENCH INCLINED TOWARD DRAIN TEMPORARY FILL LEVEL MINIMUM 12" COVER BACKFILL MINIMUM 4" DIAMETER APPROVED SOLID OUTLET PIPE **APPROVED PIPE TYPE: SCHEDULE 40 POLYVINYL CHLORIDE (P.V.C.) OR APPROVED EQUAL. MINIMUM CRUSH STRENGTH 1000 Ps 12" MINIMUM *FILTER ROCK TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EQUAL: SIEVE SIZE PERCENTAGE PASSING 1" 100 90-100 40-100 NO.4 25-40 NO. 30 5-15 NO. 50 0-7 NO. 200 0-3 NOT TO SCALE L TYPICAL BACKDRAIN DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 22 of 26 FINISH SURFACE SLOPE MINIMUM 3 FT PER LINEAR FOOT OPEN GRADED AGGREGATE* TAPE AND SEAL AT COVER CONCRETE COLLAR PLACED NEAT -... COMPACTED FILL 1 ''' "- MIRAFI 140N FABRIC OR 4J APPROVED EQUAL 4" MINIMUM APPROVED PERFORATED PIPE (PERFORATIONS DOWN) \ MINIMUM 2% GRADIENT \ TO OUTLET TYPICAL "— BENCH INCLINED BENCHING TOWARD DRAIN -"-------- 2.0% A MINIMUM 4" DIAMETER SOLID OUTLET PIPE SPACED PER SOIL ENGINEER REQUIREMENTS TEMPORARY FILL LEVEL MINIMUM MINIMUM 4" DIAMETER APPROVED 12" COVER SOLID OUTLET PIPE L 12" MINIMUM *NOTE: AGGREGATE TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EQUAL: SIEVE SIZE PERCENTAGE PASSING 100 1" 5-40 3/4 0-17 0-7 NOT TO SCALE NO. 200 0-3 BACKDRAIN DETAIL (GEOFRABIC) STANDARD SPECIFICATIONS FOR GRADING Page 23 of 26 . FILL SLOPE CLEAR ZONE —/ Icoc 3 SOIL SHALL BE PUSHED OVER I EQUIPMENT WIDTH ROCKS AND FLOODED INTO J / VOIDS. COMPACT AROUND S AND OVER STACK BOULDERS END TO END. DO NOT PILE UPON EACH OTHER. 10, FILL SLOPE ol STAGGER 10' MIN ROWS iCOMPETE NOT TO SCALE ROCK DISPOSAL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 24 of 26 FINISHED GRADE BUILDING I - NO OVERSIZE, AREA FOR 10, FOUNDATION, UTILITIE AND SWIMMING POOLSS, 1 - 0 WINDROW J 5' MINIMUM OR BELOW DEPTH OF DEEPEST UTILITY TRENCH (WHICHEVER GREATER) TYPICAL WINDROW DETAIL (EDGE VIEW PROFILE VIEW NOT TO SCALE ROCK DISPOSAL DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 25 of 26 SLOPE F STREET 15' GENERAL GRADING RECOMMENDATIONS CUT LOT —ORIGINAL GROUND - - - - - - - - TOPSOIL, COLLUVIUM AND WEATHERED BEDROCK -_ 5' MIN OVEREXCAVATE - - UNWEATHERED BEDROCK AND REGRADE CUT/FILL LOT (TRANSITION) ORIGINAL ...—GROUND - -• - - - -'MIN 01 .00 lo ' M IN OVEREXCAVATE AND REGRADE -rI'IJ VVL.rtll ILrLLJ I BEDROCK UNWEATHERED BEDROCK - NOT TO SCALE TRANSITION LOT DETAIL STANDARD SPECIFICATIONS FOR GRADING Page 26 of 26 COMPACTED FILL TOPSOIL, COLLUVIUM AkIF, AIA1JDr,