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669, Extention to previously approv, Studies & Reports• 3 ineA0054.• AUG 13 2003 TENTATIVE CONCLUSIONS AND RECOMMENDATIONS (draft ITY OF ROLLO\ G HILLS SY General Based on an evaluation of the site conditions and findings of this investigation, it is concluded that the subject property is suitable for the proposed development from a geotechnical engineering viewpoint provided the following conclusions and recommendations are incorporated into design criteria and project specifications and are implemented during construction. Depending upon final grades of the project and the location of the proposed structure, conventional footings rested on undisturbed bedrock or compacted fill may be utilized to provide support of the proposed structures. As an alternate, caissons or friction piles embedded in undisturbed bedrock may also be utilized to provide support of structural Toads. ' Section 111 Statement As per Section 111 of the County Building Code, it is our opinion that the subject site will be safe for the proposed construction against hazard from landslide, settlement or slippage from the geotechnical engineering viewpoint and the proposed grading and construction will not adversely affect the stability of the adjacent properties provided the recommendations presented in the report are incorporated into the project design, plans and specifications and are carried out during construction of the project. Restricted Use Area A portion of the site area involves an ancient landslide. If the existing landslide will not be treated or stabilized during future grading. the area of the landslide will be designated as 'Restricted Use Area'. No structures shall be located within the restricted use area. The existing natural slope areas having slope gradient steeper than 1.5 horizontal to 1 vertical may cisc be designated as 'Restricted, Use Area'. HU ASSOCIATES, INC. HA-4830-2 April 07, 2003 Site Preparation General -2- i Precautions should be taken during the performance of all work under the following sections, especially if construction is performed during the rainy season of approximately October 15 to April 15. Protection should be provided to the work site, particularly excavated areas, from flooding, ponding, and inundation due to poor or improper temporary surface drainage. During .periods of impending inclement weather, temporary provisions should be made to adequately direct surface drainage, from all sources, away from and off the work site and to provide adequate pumps and sumps to handle any flow into the excavations. The Earthwork Contractor is responsible for the satisfactory completion of all earthworks in accordance with the plans and geotechnical reports, and in accordance with the City of Rolling Hills Grading ordinance. The Geotechnical Engineer is the representative of the Owner/Builder for the purpose of implementing the report recommendations and guidelines. These duties are not intended to relieve the Earthwork Contractor of any responsibility to perform in a workman -like manner, nor is the Geotechnical Engineer to direct the grading equipment or personnel employed by the Contractor. Site Clearing Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods,. stumps, trees, roots of trees and otherwise deleterious natural materials from the areas to be graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill areas. HU ASSOCIATES, INC. • • • HA-4830-2 April 07, 2003 -3- Debris generated during clearing, grubbing and/or demolition operations should be wasted from areas to be graded and disposed of off -site. During site grading, .laborers should clear any roots, tree branches, and other deleterious materials missed during clearing and grubbing operations from all areas to receive fill. The depths of excavation should be reviewed by the Soils Engineer during actual construction. Any surface or subsurface obstructions, or questionable material, encountered during grading should be brought immediately to the attention of the Soils Engineer for proper exposure, removal or processing as directed. No underground obstructions or facilities should remain in any structural areas. 1 , Trees and Surface Vegetation Removal of designated trees and shrubs in areas of proposed construction should include rootballs. Resultant cavities should be cleansed of loose soils and roots and rolled to a firm unyielding surface prior backfilling. Grass and weed growth in areas of future construction should be stripped and disposed of off site: Stripping should penetrate three to six inches into surface soils. Any soils sufficiently contaminated with organic matter (such as root systems or stripping mixedinto the soils) so as to prevent proper compaction shall be disposed of off site or set aside for future use in landscape areas. Ground Preparation Any topsoil, slopewash, colluvium, alluvium and rock materials that are considered unsuitable by the Geotechnical Engineer should be removed prior to fill placement. Remaining voids created during Site clearing caused by removal of trees, foundations basements, irrigation facilities, etc., should be excavated and filled with compacted fill. I-IU ASSOCIATES, INC. • • HA-4830-2 April 07, 2003 -4- If malodorous or discolored soils or soils thought to contain significant levels of contaminants are encountered, an environmental consultant should be notified for recommended methods of handling and/or removal from the site. After the approval of site clearing and deleterious removals, loose surficiai soil material, uncompacted fill, alluvium, and weathered bedrock should be over -excavated to expose competent bedrock. After approval of the over excavation and prior to placement of any compacted engineered fill materials, the exposed removal bottoms should be scarified to a minimum depth of six (6) inches. The area should then be moisture conditioned to 3 percentage points above optimum moisture, and then compacted in -place to at least 90 percent of the maximum laboratory density. Landslide The existing landslide within the proposed construction area shall either be completely removed or be stabilized with buttress fill. Design of the buttress is to be provided by the Soils Engineer when the proposed grades of the project are established. Fill Placement Subsequent to clearing and removals, areas to receive fill should be scarified to a depth of 10 to 12 inches, moisture conditioned and compacted The moisture condition of the processed ground should be at or slightly above the optimum . moisture content as determined by the Geotechnical Engineer. Depending upon field conditions, this may require air drying or watering together with mixing and/or discing. HU ASSOCIATES, INC. HA-4830-2 April 07, 2003 -5- All new fill shall be brought to near optimum moisture, placed in layers not exceeding 8 inches — thick, and compacted to at least 90 percent of the maximum laboratory density. Compaction characteristics of all fill soils shall be determined by ASTM D-1557-00 standard. The field density and degree of compaction shall be determined by ASTM D-1556, or by other ASTM standard methods, which are acceptable to the governing public agency. Cut/Fill Transition In order to provide a uniform building surface and reduce potential differential settlement, the cut portions of pads exposing both cut and fill at proposed grade extending a minimum of 3 feet outside of building lines should be over -excavated a minimum of 3 feet below the base of the footings or 3 feet below the bottom of slab, whichever be the case, and replaced with approved compacted fill. ..SLOPES Unless otherwise recommended by the Geotechnical Consultant and approved by the regulating agencies, all permanent fill or cut slopes should not be steeper than 2 horizontal to 1 vertical. Except as specifically recommended otherwise, compacted fill slopes should be over -built and cut back to grade, exposing the firm, compacted fill inner core. The actual amount of over- building may vary as field conditions dictate. If the desired results are not achieved, the existing slopes should tie over-excavated'and reconstructed under the guidelines of the Geotechnical Consultant. The degree of over -building 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 over -built slope surface. HU ASSOCIATES, INC. HA-4830-2 -6- April 07, 2003 Compacted fills placed on natural slope surfaces inclining at 5 horizontal to 1 vertical or greater, should be placed on a series of level benches excavated into competent foundation materials. Fill shall be property benched into firm bedrock or compacted fill as directed by the project engineering geologist and/or soils engineer during grading. Typical benching should include 4- foot verticals exposing approved, competent material. Care should be taken during grading not to spill loose materials over slopes to remain natural.— Should loose soil be spilled onto natural slopes by the grading contractor, removal of the loose i fill will be required. Where placement of fill above a natural slope or above a cut slope is proposed, the fill slope configuration as presented in the accompanying Standard Details should be adopted. i For pad areas above fill slopes, positive drainage should be established away from the top -of - slope. This may be accomplished utilizing a berm and pad gradients of at least 2 percent in soil areas. Expansive Soils Based on the results of laboratory testing, the on -site surface and near -surface soils exhibit "high" expansion potential, as described in UBC Table No. 18-I-B. These values should be verified at the completion of site grading. The minimum reinforcement criteria for footings and slab presented in the following sections are subject to the approved of the Project Structural Engineer: Actual design should be based on the current U.B.C. and the final test results at the completion of grading. Seismic Design Parameters Based on the results of this preliminary soil investigation and in accordance with Chapter 16, Division IV of the 1997 Uniform Building Code, the following seismic data are applicable to the subject site. . HU ASSOCIATES, INC. - HA-4830-2 -7- April 07; 2003 Seismic Zone Factor, Z Soil Profile Type Seismic Source Type Near -Source Factor, Na Near -Source Factor, Nv Seismic Coefficient, Ca Seismic Coefficient, C,, 0.4 Sc B 1.10 1.33 0.44 0.75 Foundation Design Recommendations Conventional Footings on Bedrock An allowable bearing value of 2500 pounds.per square foot is recommended for spread . footings of at least 15 inches in width placed at a depth of at least 2 feet below the lowest adjacent final grade and founded at least 12 inches into undisturbed bedrock. This value may be increased by 200 pounds per square foot for each additional foot in width and 350 pounds ' per square foot for each foot in depth over the minimum, to a maximum of 4000 pounds per square foot. The bearing value is for dead plus live load and may be increased by one-third for momentary wind or seismic loads. Spread Footings on Compacted Fill Provided the fills are compacted as recommended, footings placed at a depth of at least 2 feet below the lowest adjacent final compacted surface may be designed for an allowable bearing value of 2000 pounds per square foot. The bearing value is for dead plus live load and may be increased by one-third for momentary wind or seismic loads. HU ASSOCIATES, INC. HA-4830-2 -8- April 07, 2003 Cast -in -place Pier in Bedrock An allowable bearing value of 3,500 pounds per square foot is recommended for piers of at least 2 feet in diameter, placed at a depth of at least 5 feet into undisturbed bedrock. This ' value may be increased by 250 pounds per square foot for each additional foot in diameter and 400 pounds per square foot for each foot indepth over the minimum, to a maximum of 6,000 pounds per square foot. The bearing value is for dead plus live load and may be increased by one-third for momentary wind or seismic Toads. Cast -in -place Friction Piles in Bedrock Piles may be designed for skin friction between concrete and bedrock. An allowable skin friction value of 500 pounds per square foot for bedrock may be used for the pile design. The piles should be embedded at least 10 feet into bedrock. Uplift values may be assumed as one- half of the downward capacity. Recommended downward and uplift capacities are for dead plus live loads and may be increased by 50 percent for combined dead, live and seismic forces. All piers or piles shall be tied with grade beams in both directions. Piles may be assumed to be fixed at ten (10) feet below existing grade, or five (5) feet below natural soils, whichever is lesser. The weight of the concrete in the pile maybe neglected in considering the allowable pile load, provided the bottom of piles is cleared of loose or disturbed soil before pouring concrete. Should this prove impractical, the pile should be lengthened sufficiently to carry the weight of the pile. Drilled holes should be filled with concrete as soon as possible after excavation. HU ASSOCIATES, INC. • • HA-4830-2 April 07, 2003 -9- The capacity is based on the strength of the bedrock; the compressive and tensile strength of the pile section should be checked to verify the structural capacity of the piles. Care should be taken in setting reinforcing cages and all concrete should poured through a tremi since the walls of the pile excavations will tend to slough or cave if disturbed by contact. The tremi pipe shall be placed at the bottom of the pile hole and shall be well embedded in the concrete at airtime. Extreme care should be taken to provide the full design base dimensions and to be sure all loose or disturbed soil and slough material is cleaned out of the excavation before pouring concrete. ' Foundation Settlement Total and differential settlement between adjacent foundations is expected to be negligible if foundations are placed in competent bedrock as recommended. Footing Reinforcement Continuous footings should be reinforced with at feast four No. 4 bars, two near the top and two near the bottom of the footings. Reinforcement of isolated footings and piers or piles shall be utilized as deemed necessary by the Structural Engineer for the project. This reinforcement is based on soil' characteristics and' is not intended to be in lieu of reinforcement necessary to satisfy structural considerations. Building Clearance From Ascending Slope Section 1806.4.2 of the Los Angeles County Building Code requires that building below slope shall be set a distance equal to one-half of the slopeheight with a minimum of 3 feet and a maximum of 15 feet to provide protection from slope drainage, erosion and shallow failures. This will require a rear yard retaining wall at a distance of 15 feet from the building at the same level as the top of the garage rear wall. HU ASSOCIATES, INC. I HA-4830-2 -10- April 07, 2003 Foundation Setback From Descending Slope Footings located on/or adjacent to a descending slope shall be placed at sufficient depth to . .. provide horizontal setback from the slope surface. The required setback of the Building Code is, 1/3 the height of the slope with a minimum of five feet and a maximum of 40 feet measured horizontally from the base of the foundation to the slope face. Foundation Inspections All foundation excavations should be inspected and approved by the Soils Engineer prior to placement of forms, reinforcement or concrete. The excavations should be trimmed neat, level and square. All loose, sloughed and moisture softened materials should be removed prior to the placement of concrete.. Materials from foundation excavations should not be spread in slab -on -grade areas unless they are compacted and tested. Footings should be located below a line measured upward at a 45-degree angle from the bottom of the adjacent footings or utility trench, unless reviewed and approved by the Soils Engineer. Lateral Design An allowable lateral bearing value against footings or pile and pier shafts of 200 pounds per square foot per foot of depth for compacted fill and 400 pounds per square foot per foot of depth for bedrock, to a maximum of 4000 pounds per square foot, may be used provided there is positive contact between the vertical bearing surface and compacted fill or undisturbed bedrock. Friction between the base of the foundations and the bedrock may be assumed to be 0.35 times the dead load. When combining passive pressure and friction for lateral resistance, the passive component should be reduced by one-third. For isolated piles or piers, the recommended lateral bearing value may be doubled. HU ASSOCIATES, INC. HA-4830-2 -11- April 07, 2003 Slabs On Grade Floor Slabs Slabs on grade should be cast over properly prepared subgrade. Any loosened or over - excavated soils should be wasted from the site or properly compacted in -place. Subgrade soils disturbed due to installationof utility lines should either be completely removed... or be properly compacted prior to concrete, pour. The subgrade fill soils should be moisture - conditioned to obtain near optimum water content and then compacted to at least 90 percent of the maximum dry density as determined by the ASTM D-1557-00 compaction test method. It should be recognized that minor cracks normally occur in concrete slabs due to shrinkage during curing or redistribution of stresses and thus, some cracks should be anticipated. Such cracks are not necessarily indicative of excessive vertical movements. Slab Reinforcement Floor slabs constructed on -grade should be a minimum thickness of 4 inches and be reinforced with at least No. 4 bars spaced 16 inches on centers, both ways. All slab reinforcement should be supported on concrete chairs or brick to ensure the desired placement near mid -depth. The above criteria are recommended to minimize potential distress to floor slabs related to the effects of subgrade soil conditions. The Structural Engineer for the project may need to address other factors that may require modification of the above recommendations. HU ASSOCIATES, INC. • i , HA-4830-2 April 07, 2003 Moisture Barrier -12- A moisture barrier beneath slabs -on -grade, consisting of a waterproof vapor barrier, such as a plastic membrane of at least 10 mils in thickness, is recommended in areas where slab moisture would be detrimental. The membrane should be overlain by a minimum of 2 inches of clean sands to provide a working surface and aid in concrete curing. It is important that the soil subgrade, which will support the concrete slab, is maintained at the "as -graded" or has a sufficient soil water content. Prior to slab construction, the water content of the soil subgrade should be measured to verify that the subgrade has not dried out significantly. Itis suggested that slab areas be thoroughly moistened prior to placing of moisture barrier and pouring of concrete. Retaining Wall Wall Footings Retaining wall footings rested on undisturbed bedrock may be designed for the same allowable bearing value as given in the previous sections for building foundations. Active Earth Pressures Retaining walls should be designed to resist lateral earth pressure exerted by the retained compacted backfill plus any additional lateral forces that will be applied to the walls due to surface loads placed at or near the wall or from footings behind the walls. It is recommended that retaining walls that are free to rotate at the top be designed for the following equivalent fluid pressure: HU ASSOCIATES, INC. HA-4830-2 -13- April 07, 2003 • Surface Slope of Equivalent Retained Material Fluid Pressure Horizontal to Vertical Pounds per Cubic Foot Level 40 3 to 1 43 2 to 1 55 Walls that are restrained against movement or rotation at the top should be designed for the at - rest equivalent fluid pressure. An at -rest equivalent fluid pressure of 55 pounds per cubic foot can be used for wall with level soil backfill. The lateral earth pressures assume that a permanent drainage system will be installed so that hydrostatic water pressure will not be developed against the walls. If a drainage system is not provided, the walls should be designed to resist an external hydrostatic pressure due to water in addition to the lateral earth pressure. Wall Drainage i All retaining walls should be waterproofed and/or damp -proofed, depending on the desired moisture protection. The walls should be provided with weep holes or perforated pipe and gravel subdrain to prevent entrapment of water in the backfill. Weep holes should consist of unmortared joints in block walls or two-inch diameter round holes in poured concrete walls. The openings should be at least 3 inches above finished grade to prevent surface water from flowing back into the holes. Any water that may accumulate in the drainage material should be collected and discharged by a 4-inch diameter, perforated PVC Schedule 40 or ABS SDR-35 pipe placed near the bottom of the drainage material but at least one foot below the interior floor. The pipe should be embedded in drainage material up to two -third of wall height. Pipe perforations shall be at 45- degree angles (approximately) to one another on opposing sides of the pipe every 8 to 12 inches. The pipe perforations should be placed with the holes down, and should not be greater than 1/4 inch in diameter. HU ASSOCIATES, INC. HA-4830-2 April 07,-2003 -14- The subdrain should outlet at appropriate discharge locations that will ensure all discharge will not scour or erode the surrounding soil, and the pipe will not become damaged or clogged. The outlet pipe should be a solid pipe that meets minimum specification set forth above for the subdrain pipe. The drainage material that will be used to backfill the wall should consist of 3/4 to 1-1/2 inch clean durable, coarse aggregate. The drainage material should be separated from ail adjacent soil by Mirafi 140NL, or approved equivalent. The fabric should be handled in accordance with the respective manufacturers requirements, and should be constructed such that all fabric aoverlaps are a minimum of 12 inches. Walls retaining upslope should be provided with at least one foot of freeboard. A concrete paved.drainage swale should be placed at the top of the wall to intercept runoff and conduct water to the street. Wall Backfill Prior to backfilling, the excavation between retaining walls and the temporary cut bank should be cleared of all loose materials, debris, and construction materials, etc. All of the existing uncertified fills should be completely removed to underlying native soil. Proper compaction of the backfill will be necessary to reduce settlement of the backfill. Some • settlement of the backfill should be anticipated and any utilities and sidewalks supported therein should be designed to accept differential settlement, particularly at the points of entry to the structure. All wall, backfill should be placed in horizontal lifts not more than 8 inches in thickness, watered as necessary to achieve near optimum moisture conditions, and mechanically compacted to at least 90 percent of the ASTM D-1557-00 standard. Flooding or jetting of backfill materials should be avoided. Probing and testing should be performed by the project soils engineer to verify proper compaction. HU ASSOCIATES, INC. HA-4830-2 -15- April 07, 2003 Where space limitations do not allow for conventional backfill compaction operations, the space should be backfilled with pea gravel. The pea gravel backfill should be placed in lifts of no • more than 2 feet in thickness and should be compacted with vibratory equipment. Ideally, the top of two feet of backfill, exposed to water infiltration should be consisting of clayey material so that.arelatively impervious condition is developed. Contractors should be informed that the use of heavy compaction equipment within dose proximity to retaining walls could cause excessive wall movement and/or earth pressure in excess of design values. Waterproofing II Rooms located below grade have a history of moisture intrusion, seepage, and leakage. Conventional waterproofing materials, such as asphalt emulsion, have often proved ineffective. Certain precautions can be taken to reduce the possibility of future seepage problems. Where this occurs, very special consideration should be given to waterproofing of the walls to prevent damage to the interior of the house or garage. Unless dampness is acceptable on exterior wall faces, waterproofing should also be incorporatedinto exterior retaining wall . design. Although the project architect is the party who should provide actual waterproofing details, it is suggested the waterproofing consist of a multi -layered system such as an initial generously applied layer of hot -mopped asphalt over which a layer of construction felt could be applied, then thoroughly mopped again with hot asphalt. In the case of all retaining walls, it is suggested that a layer of 10-mil Visqueen be placed as a finish layer. The multi -layered system should be covered with protective foam -board, or similar, to prevent damage during the backfilling operation. Even though groundwater is not expected to be a significant problem at this site, extreme care should be exercised in sealing walls against water and water vapor migration. Where retaining walls are planned against interior space, continuity should be provided between the aforementioned wall moisture proofing on the back of the retaining wall and the moisture barrier HU ASSOCIATES, INC. • • HA-4830-2 -16- April 07, 2003 typically placed under slab areas. This waterproofing is necessary to prevent the foundation concrete acting as a wick through which moisture migrates to the interior space despite wall moisture proofing. Excavation Excavation should be in accordance with all applicable requirements of the State of California Construction and General Industry Safety Order, the Occupational Safety and Health Act of 1970, the Construction Safety Act, and all other public agencies having jurisdiction. Construction specifications should clearly establish the responsibilities of the contractor for construction safety in accordance with CAL/OSHA requirements. No excavation shall be made during unfavorable weather. It is recommended that the excavated banks be entirely covered with plastic sheets when threatened by rains. When the excavation is interrupted by rain, operations shall not be resumed until the Soil Engineer indicates that conditions will permit satisfactory results. It should be understood that the contractor shall supervise and direct the work and he shall be responsible for all construction means, methods, techniques, sequences and procedures. The contractor will be solely and completely responsible for conditions at the job site, including safety of all persons and property during the performance of the work. Periodic or continuous inspection by Hu Associates, Inc. is not intended to include verification of dimensions or review of the adequacy of the contractor's safety measures in, on or near the construction site. I-IU ASSOCIATES, INC. EG:L BORING LOG B-la PROJECT LOCATION: 3 Appaloosa Lane, Rolling Hills, Cafifomia PROJIECT NO: 03-137-010G Sar •tple 3 E. Y S o m :J m 5- 10- USCS Symbol CL CB'sr. � U go N e o �v S: Standard Penetra: or. Test R: Ring SamD.e DATE DRILLIED: 02-17-03 SAMPLE METHOD: 24-inch Bucket Auger ELEVATION: NIA LOGGED BY: HJ Description of Material Fill: Silty clay, dark gray, very moist, soft Bedrock: claystone, brownish gray, with interlayers of diatomaceous claystone, layer thickness up to 12", firm, massive, weathered 15— 20— 25—., 30- 35— Bedrock: sandy claystone, brownish gray, firm to medium hard, poorly bedded Bedding: N 41 W / W 44 @ 12 feet Bedrock: sandstone, brownish gray, the grained, firm, massive Bedrock: claystone and diatomaceous claystone interlayers, reddish brown to Tight gray, firm, massive Bedrock: sandy claystone, brownish gray, medium hard to hard, poorly bedded Bedding: N 44 W / W 34 @ 24 feet Bedrock: sandstone. fight gray, very fine grained, dry, medium hard, massive Bedrock: claystone, light gray, diatomaceous, fine to medium hard, massive Bedrock: sandstone, yellowish brown, fine grained, medium hard to hard, @ 40 feet, diatomaceous claystone interlayers, poorly beaded, near horizontal . , t 4q-n c4,R 7.44 -93 dii:VO 60 EO Jdd EGL 45— . 50 BORING LOG B-lb PROJECT LOCATION: 3 Appaloosa Lane, Rolling Kris, California PRO.IECT NO: 03-137-01OG Ss nple Undisturbed 55- 60- 65- 70- 75— USCS Symbol c r. ❑ S: Standard Penetration Tes: R: Ring: Sample DATE DRILLIED: 02-17-03 SAMPLE METHOD: 24-inch Bucket Auger ELEVATION. NIA LOGGED BY: HJ Description of Material Berock: sandstone, yellowish brown, fine grained, medium hard to hard @ 40 feet, diatomaceous claystone interlayers, poorly bedded, near horizontal Bedrock: sandstone, yellowish brown, fine grained, medium hard to hard Total Depth 50.0 feet No Groundwater Encountered Hole Backfifled cl t'9E0 St76 29S OJ3 HI1:t.O EO co add EGL "' BORING LOG B-2 PROJECT LOCATION: 3 Appaloosa Lane. Rolling Hills. California PRC JECT NO: 03-137-010G Sample - o a d t rn y o ((-) o co▪ m n 5 10- 15-" 20- 25- 30- 35- CL CL c � U 0 0 0 S: Standard Penetration Test ' Ring Sampte DATE DRILLIED: 02-17-03 SAMPLE METHOD: 24-inch Bucke` Auger ELEVATION: NIA LOGGED BY: H.I Description of Material Silty clay, cark gray, very moist, organic, soft to medium stiff, top 6" root, Alluvium: silty clay, brownish gray, moist, medium stiff, with s'Jbangular sandstone fragment up to 3" Bedrock: landslide debris claystone, light yellowish brown, weathered, with ligh! gray pockets of diatomaceous clay up to 6" in size and sandstone debris up to to 2" @ 17 feet, approximate 18" thick of silty clay, dark gray, medium stiff to stiff, appears to be residual soils between landslide debris © 21 feet, approximate 18" thick of silty clay Bedrock: yellowish brown claystone and light gray diatomaceous ciaystone mixture, firm, moist, massive @ 36 feet, shale pocket approximate 6" thick, gray, firm Bedding: N 54 IN / S 66 Total Depth 38 Feet No Groundwater encountered Hole BacY,filled E ' d f•9ED Sb6 295 193 dl l : ,.D ED ED Jdd ECL 5- 10- 15- 20- 25- 30- .r ttuKirlb LOG 8-3 PRO. ECT LOCATION: 3 Appaloosa Lane, Rolling Hills, California PRO.. ECT NO: 03-137-010G Sample Undisturbed S: Stanyara Penetration Test R: Ring Sample Fill: DATE DRILLtED: C2-17-03 SAMPLE METHOD:24-inch Bucket Auger ELEVATION: N,A LOGGED BY: NJ Description of Material Silty clay, dark gray, very moist, organic, soft to medi,am stiff, top 6" rooty CL CL Bedrock: .. claystone, brownish gray, firm, very moist, massive, weathered Bedrock: diatomaceous claystone, light gray, poorly bedded Bedding: N 38 W / S 40 @ 7 feet Bedrock: claystone and diatomaceous claystone interlayers @ 12 feet, sandy daystone, poorly bedded @ 14 feet, 6" thick siliceous sandstone, very hard, massive @ 23 feet, 6" thick sandstone, fine grained, light gray to brownish gray, massive @ 26 feet, sandy claystone, dark brownish gray, poorly bedded Bedding: N 18 W / `tip'.! 20 @ 12 feet N2W/W46@26feet N4W/W40@21feet Bedrock: intact claystone; with diatomaceous claystone interlayers, moderately bedded, layer thickness 114 to 2", weathered, Bedding: N 32 W / W 34 W @ 28 feet N12W/W20@31feet Bedrock: Claystone, very moist, massive, weathered 35- Total Depth 40 Feet No Groundwater Encountered ' Hole Backfilled ' ' b-d b9ED Sb6 295 193 dal:VD EO ED .,de EG: L EltbRING LoG B-4 PROJECT LOCATION: 3 Appaloosa Lane, RollingH:lis, California PROJECT NO: 03-137-010G Sz mole' Undisturbed 5 10- 15— . 20 USCS Symbol CL Silty clay, dark gray, very moist, organic, soft to medium stiff, top 6" rooty S: Standard Penetrative Test E R Ring Sar:ipla DATE DRILLIED: 02-17-03 SAMPLE METHOC: ,24-inch Bucket Auger ELEVATION: NIA LOGGED BY: H Description of Material Fill: Landslide debris, mixture of claystone, brownish gray, soils dark gray, firm Bedrock: sandstone, fined grained, firm, slightly moist, brownish gray, massive Total Depth 20 Feet No Groundwater Encountered Hole Backfilled 25- 30- 35— S • d t'9ED St'6 29S 103 d2T :trD ED ED Jdd • EGL . 5 10 15- 20 — 25- 30- 35- tt ��Ftlt•I� LbG ti-5 PRO.. ECT LOCATION: 3 Appaloosa Lane, Rolling Hills, Califomia PRO.. ECT NO: 03-137-010G Sample Undisturbed S: Standard Penetratio, Tes: R: Ring Sarpte DATE DRILLIED: 02-17-03 SAMPLE METHOD. 24-Incr. Bucket Auger ELEVATION: NIA LOGGED BY: HJ Description of Material Fill: silty clay, brownish gray, soft to medium stiff, moist, rooty Bedrock: Sandy ctaystone, brownish gray, moist, poorly becded Bedding: N24WIW18@7feet Bedrock: sandstone, I`ghr brownish pray, massve, occasional hard sandstone layers up to 6" Total Depth 21 Feet No Groundwater Encountered .Hole Backfitled 9-d 1,9E0 St'6 29S 1E3 d21: D ED ED Jdd • • EGi. ' Boiil dt4 Lt3ti 8-6 PROJI::C1 LOCATION: 3 Appaloosa Lane, Rolling Hills, California PROJI::CT NO: 03-137-010G Sanple USCS Symbol -. CL 5- 10- 15- 20- 25 S: Standard Peneration Tes R: FZno Sample U ,n 0 'Z.. DATE DRILLIED: 02-17-03 SAMPLE METHOD: 24-inch l?uckc: Auger ELEVATION: NIA LOGGED BY: HJ Description; of Material Fill: silty clay, dark gray. moist, soft to medium stif, rooty CL Fill: silty clay, dark gray, with subanguiar sandstone fragments up to 3", moist, medium stiff to stiff Bedrock: claystone, sandy, brownish gray, slightly moist, firm, poorly bedded 30— - - 35— Bedrock sandstone. calcareous, medium hard to hard, brownish gray, rn.assive @ 15-17 feet, coarl fossil, medium hard, massive Totaf Depth 21 Feet No Groundwater Encountered Hole Backfilled /. • d 1,9ED S 'B 29S 103 d2I : VD CO ED Jd13 , 005 GR� 4.1A1• -Cr to , r:.9 rIINUEi:S°N. }} r;•• } :,rc. r 'kj10.• IA' AliffeLl \6. 1.137, • 'illTR�$ ''/11�! 04:" "I"'� fJj• _•.... •�w_,(,,�ly,�l. � ,...r ,;jl�� ._ a:d ,r• 'ev., • w • Ar:: ,tom' y'•. j, • ,401 1, 4.4•� 's. .,. S tq: y:• r off•• „•I • ' ,1': 4, r h '..it • `r` ,, . r ; �h ,. i ,.C,. , ,/' A' • TEL:310 3 92., 3 7, 1 J!iJ 1 11 • l•: 1 ` r 2.1-E9ZI-S0I S6 p} 1i 3 1,47C'an corrn 1A•i.-07'03'WED1 17.31 CR'SS GUNDERSON ARCH MA1•-7-2003. 09.:53P PROM: �. TEL.310 373 S27' 913103739277 • °a•7 F U4)- 1' IF MINIMUM -� 4' DIAMETER PERFORATED //k. . PIPS BACKDRAIr 4" DIAMETER NON -PERFORATED PIPE LATERAL DRAIN SLOPE PER PLAN .. BENCHING H/2 /!k //4 > PROVIDE BACK, DRAIN PER BACKDRAiN QETAIL. AN ADDITICAAL BACKDRAIN AT MID•SLOPF. WILL BE REQUIRED FOR SLOPE IN EXCESS OF 40 FEET HIGM. KEY -DIMENSION PER SOILS ENGINEER TYPICAL BUTTRESS FILL l:'L'Uposed Sin471,-Family tWsidenc, .3 11APzi1owi,t+ I•arl? Rolli,ncj Flili.v, Gollfunrlia 1111 ASSOCIATES, INC. r,otorhrdrnl linRlnoownx Cun.,mitunb, PROJECT Na, HA 4' 3U ,FLA'1'lti 3 LUNATION - i EET - 3-1 330] A akx+sa - .are ! 7 SECTION A -A' -A" SCALE: - r cr. i DiI 1 I an i ii' Appaaaa Road j E2 - , x f Lang t r,•: j F s�-1--1 I - ��-- ':---.1--` '" ' / '•� - -.. Buttress rill ,tmt+ { D L)-lc- YTut Tr. -at IIan45'4 1 Trul Fc -re ior Ndnsr l traarruc i✓=t Uk-.i6.ss tP a1rL-r It:�ec 6a� at- i c= ?7_L rIcz'er.ar�z:`�-.>>�cr;.�;r.' 7r„1. 6ri_ ri-g Grad?. —\ "nit r t cdi�n LL29ELE0T0 6:01__ MA' . -0' O3 1WED) 17;72 CSS GUNDERSON ARCH ,` (1AY- r-d023 09; 53A FRCM: TEL:310 373 8277 P 009 •:913103730277 Pq9 I INISH SURFACE SLOPE 3 PTA MINIMUM PER LINEAL FOOT APPROVED FILTER ROCK' TAPE AND SEAL AT CONTACT 4" MINIMUM DIAMETER SOLID OUTLET PIPE SPACED PER SOIL ENGINEER REQUIREMENTS . ...DURING GRADING 12' MINIMUM COVER 291, MINIMUM GRADIENT A -I DETAIL A -A' COMPACTE0 BACKFILL C 17' MINIMUM "'APPROVED PIPE TYPE Sct1 CJULE 40 POLYVINYL CHLORIDE (P. V. C•} OR APPROVED EQUAL. MINIMUM CRUSH STRENFTH 1000 P31 BACKDRAIN DETAIL (GEOFABRIC) III' ASSOCIATES, INC. COMNAC. I EU FILL SUPACB•PfA131'imGOR APPROVED EQUAL 4" MINIMUM AP ROVEu PERFORATED Mr' (PERFORATIONS DOWN) MINIMUM2%t Rfr ENT TO OUTLET BENCM INCLINtU TOWARD DFTAII TYPICAL BENCHING / TEMPORARY FILL LEVEL 4" MINIMUM D!AMF'FR APPROVED ----- SOLID OUTLET PIPE •FILTER ROCK TO MEET FOLLOWING SPECIFICATIONS OR APPROVED EQU,kL SIEVE, PERCENTAGE 0.65.4 G 11R' 100 1 5.41) 314" C-1 T 0-7 NO.2:10 0-3 L"Lupus d SiII+;i1C-Family RQ4iia;:l i:t; i AFpaloo,1d Lane Rullirly hilly, C.alifucui$ Grnucln+ical Ei inrrnng Coruuiurnts 1,PROJR CT No. HA-4fl.10-R 'PLATE -MAY. -07j 03 ;WED) 17:32 . I'!H-- r-d011_ d`J: Sst-i HUM: RS CGUNDERSON ARCN TEL:310 373 8277 0 91310373E3277 P 008 P:6 UNSUITABLE EARTH MATERIAL. LIMITS OF FINAL EXCAVATION FINAL NATURAL SLOPE r-v. MINIMUM POWNSLOPE KEY DEPTH TOE OF SLOPE SHOWN ON GRADING PLAN 15' MINIMUM EASE KEY WIDTH FILL • • 10' 1YF'ICAL dENC7H WIDTH VPItILS COMPETENT EARTH MATERIAL TYPICAL BENCH HEIGHT PROVIDE BACKDRAIN AS REQUIRED PER RECOMMENDATIONS OP SOILS ENGINEER DURING GRADING WHERE NATURAL SLOPE GRADIENT IS 5.1 OR l FS$, BENCHING IS NOT TO BE PLACED ON COMPRESSIBLE OR UNSUITABLE MATERIAL. FILL SLOPE ABOVE NATURAL GROUND DETAIL a' Propoieci 511:giu-Fam1:y Rcol:i;;;, cG 3 AppalooA T,Anis Roiling Hi11H, L'H1jror:ril ECU ASSOCTATES, INC:. G oteohnical linginwwring Consul/nnt7 PROJECT No, MA 4 FiAA frT4TE MAY. - 07 03 :11 E01 17 : 28 MAY-7-2003 09:52A FROM: CR• GUNDERSON ARCH TEL:310 373 827' 1110913103738E77 P. 002 c:2 TENTATIVE CONCLUSIONS AND RECQMMENDATIONS (draft) Unless otherwise recommended by the Geotechnicai Consultant and approved by. the regulating agencies, all permanent fill or cut slopes should not be steeper than 2 horizontal tc 1 vertical. Buttress FBI The existing landslide shall be stabilized by rneans of a buttress fill constructed in accordance with the recommendations of the soils engineer. The buttress fill shall be provided a key at the toe of the slope at the approximate location shown on the accompanying map. The key shall have a minimum width of 30 feet and be excavated to a depth of at least 10 feet below the lowest adjacent grade or 3 feet Into undisturbed bedrock, whichever is deeper. Typical buttress should be constructed .r accordance with the specifications of the accompanying Standard Detail. aThe backcut for the keyway would be about 1 horizontal to 1 vertical. It should be noted the.t the backcuts could expose' unstable materials resulting in the possibility of failure of these temporary cut Stopes. For thls reason, we recommend that keyways be excavated and backfilled as expeditiously as possible to minimize the possibility of a backcut failure. Typical subdrains for compacted fill buttresses, slope stabilization or sidehill masses, should ..... be installed In accordance with the specifications of the accompanying Standard Details, Fill Slope over Natural Slope Where placement of fill above a natural slope or above a cut slope is proposed, the fill slope . configuration as presented In the accompanying Standard Details should be adopted. HU ASSOCIATES, INC. i1A% -07 03:WED1 17:2S. CRISS G1•NDERSON ARCH McY-7-E003 09:52A FROM: TEL:310 373 8277 •13i.03738E77 P 003 F. HA-4830-2 May 5, 2003 For pad areas above fill slopes, positive drainage should be established away from the top-oi slope. This may be accomplished utilizing a berm and pad gradients of at east 2 percent in soil areas. Prior to receiving of new fill, all of the existing fill, unstable or low -density acil within the proposed construction area should be completely removed to underlying competent soil anc(n r bedrock and replaced with properly compacted soils. The exposed bottom surface in each j removal area should first be scarified to a depth of at least 8 inches, processed, watered or a ' dried as necessary to achieve near optimum moisture conditions, and then compacted in-plec to at least 90 percent of the maximum laboratory density. Actual depth of removal is to be determined in the field at the time of grading. All new fill shall be brought to near optimum moisture, placed in layers not exceeding 8 inchin thick, and compacted to at least 90 percent of the maximum laboratory density. ' Compaction characteristics of all fill soils shall be.,determined by ASTM D-1557-00 standard... The field density and degree of compaction Shall be determined by ASTM D- 1 556, or by cth a; ASTM standard methods which are acceptable to the governing public agency. Fill slopes should be carefully constructed and backrolled during grading to obtain the specified degree of Compaction. These slopes should be either 1) over -built and cut back to grade, exposing the firm, compacted fill Inner core, or 2) built to line and grade and any low - density material present after "backrolling" during placement should be compacted to the specified density by using cable -lowered sheepsfoot. Care should be taken to maintain the desired moisture conditions and/or re-establishing same as needed prior to backrolling. Upon achieving final grade, the elopes should again be moisture conditioned and then be grid -rode d to achieve a relatively smooth surface and uniformly compact condition. ill ASSOCTATF.S, A. TEL 31U 37 62'" P 00. MA1. - 7 0 31cU1 17.30 CRISS GUNDERSON ARCH •913103738277 MAY-7-2003 O9:5ca FROM: HA•4830.2 i May 5, 20C3 Compacted fills placed on natural slope surfaces inclining at 5 horizontal to 1 vertical or I greater, should be placed on a series of level benches excavated Into competent foundation materials. Fill shell be property benched into firm bedrock or firm natural soils as directed by the project engineering geologist and/or soils engineer during grading. Typical benching should include 4-foot verticals exposing approved, competent material. Care should be taken during grading not to spill loose materials over slopes to remain natural: Should loose soli be spilled onto natural slopes by the grading contractor, removal of the Ioo'3a flII will be required. HU A$SQ(1IATES, INC. S2,0. 874: g3 eoo 8 S(E4-0 830 B.l o 4o0 - DixtVEu)Qy S C C i lc7N ,bz o o,'-iO/-// /24-75, 40' flacie AUG 1 3 ZE3 CITY OF ROLLING HILLS