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HomeMy WebLinkAbout11 CLEAR WATER - SOILSI � m c= TFi r—n r— 1 801 Glenneyre St. • Suite F • Laguna Beach • CA 92651 r, (949) 494-2122 • FAX (949) 497-0270 September 21 2006 Mr. Eric Albert Project No: 71665-00 47 Marisol Report No: 06-5866 Newport. Coast, California 92657 Subject: Geotechnical Investigation for New Single -Family Residence Lot 28a of Tract 16456, Crystal Cove Newport Beach, California This report presents results and recommendations of a geotechnical investigation undertaken to relate onsite and certain regional geotechnical conditions to the proposed design and construction of a new two-story, 8,500+ square foot, single-family residence with swimming pool and spa at the subject property. Partial basement construction is anticipated. Field investigation and analysis for this report are based upon the proposed development depicted on architectural drawings prepared by KTGY Group, Inc. The Site Plan of the property forms the base for our Geotechnical Plot Plan, Figure 4. The conclusions and recommendations of this report are preliminary due to the absence of specific foundation plans, the formulation of which is partially dependent upon recommendations herein. Scone of Investigation The investigation included the following: 1, Review of pertinent geotechnical literature, including certain regional and site specific reports and maps. 2. Excavation and logging of four 8-inch diameter borings to determine the character and distribution of earth materials and to obtain bulk and relatively undisturbed soil samples for laboratory testing. 3. Laboratory testing of samples to determine in place moisture and density, maximum density/optimum moisture, Atterberg limits, expansion index, and corrosivity characteristics of representative materials. f September 21, 2006 Project No; 71665-00 _ Report No: 06-5866 f l Page No: 2 4. Preparation of two topographic -geologic cross sections relating site conditions to proposed improvement and depicting certain geotechnical recommendations for site development. 5. Geotechnical analysis of subsurface conditions as related to foundation design and construction recommendations. 6. Preparation of this report and illustrations. Accompanying Illustrations and Appendices Figure 1 - Geologic Location. Map Figure 2 - Seismic Hazards Location Map Figure 3 - Typical Retaining Wall Subdrain Detail Figure 4 - Geotechnical Plot Plan Figure 5 - Geotechnical Cross Section A -A' Figure 6 - Geotechnical Cross Section B-B' Appendix A - References Appendix B - Boring Logs Appendix C - Field Exploration and Laboratory Testing Appendix D - Standard Grading Specifications Appendix E - Maintenance of Graded Sites Appendix F - Utility Trench Backfill Guidelines Site Description The approximately rectangular -shaped property fronts 100+ feet on Clear Water and extends westerly 180 to 200+ feet to the rear property boundary located at the top of the slope. The lot consists of a vacant, essentially level graded pad flanked by a shallow graded westerly and southerly facing slopes. These slopes continue beyond the property line with an overall slope ratio between the subject lot and the lower pads of 2:1 (horizontal:vertical), with an estimated maximum relief of 20 and 65+ feet to the south and west, respectively. A MSE wall with a maximum height of 13+ feet is located at the toe of the west slope. The terrain to the west beyond the tract consists of the natural slope descending along the southern flank of Los Trancos Canyon. The immediately adjacent properties are graded lots and streets, currently without residential development. Proposed Improvements The proposed improvements consist of a new 8,500+ square foot, two-story residence with a partially subterranean basement. The residence will utilize wood and steel frame construction supported on retaining wall and conventional foundations, with an estimated maximum wall height of 10+ feet. Landscape areas and planters are anticipated to be accommodated with small retaining wall systems to a maximum height of 3+ feet or less. Extensive new hardscaping and P1 September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 3 l' landscaping is also envisioned throughout the back and side yards. Pool and spa designs are anticipated to utilize deepened foundations for improvements adjacent to slopes. GEOTECHNICAL CONDITIONS Geologic Settin The property is situated at the northern extension of the San Joaquin Hills, within the Peninsular Ranges geomorphic province. This province in characterized by northwest -southeast trending structural blocks that are bounded by active strike -slip faults. The San Joaquin Hills are composed of sedimentary bedrock strata within a portion of a block uplifted by these tectonic forces compressing this region of southern California. Q_r During the last glaciation when the sea level was lower and the climate was wetter, the hills I !' supporting this area were transected by a number of southwest trending drainages and creeks. The subject property is situated on the southeastern cut ridgeline for Los Trancos Canyon. This lot was graded as a compacted fill above an earthen buttress during the grading for Tract 15613. This rough grading was conducted under the observation and testing of GMU Geotechnical, Inc. (2005). Earth Materials The site is underlain at depth by sedimentary bedrock classified as the Monterey Formation on i I the basis of regional geologic mapping and this investigation. The bedrock appears to be overlain throughout the pad area of the property by compacted fill placed during the r development of Newport Coast. t As described in regional reports, the Monterey Formation bedrock in this area is composed of well bedded medium brown -gray siltstone and chert. These deposits are moderately hard to locally very hard and have favorable foundation characteristics. Given its depth below the property, this material is not anticipated to be exposed during the proposed construction. The fill deposits consist of locally derived clayey silt, placed and compacted during the mass grading development of Tract 15613. Due to near surface weathering, the upper two feet of the fill is considered unsuitable for the support of improvements. Below two feet, the fill material is firm to stiff, moist, and suitable for foundation support. Based on this study, the onsite materials have a medium expansion potential and a moderate to 1 severe soluble sulfate concentrations. Electrical resistivity tests also indicate a severe to very severe corrosivity potential for buried metal. Prior reports for foundation design following the tract grading provided recommendations for highly expansive soils. 1 September 21, 2006 Project No 71665-00 Report No: 06-5866 Page No: 4 Geologic Structure Review of the previous rough grading documents for the tract indicates the bedrock strata in the site vicinity is variably tilted to dip at low to high angles easterly and southerly. This results in a structural -topographic condition where bedding is inclined obliquely into the slope and/or steeper than slope, a supported and favorable condition for gross bedrock stability. Slope Stability Previous studies evaluated the gross stability of the tract with respect to static and pseudostatic loading, and indicated adequate factors of safety for the design grading (GMU, 2005). Further analyses are beyond the scope of this investigation. The rear slopes supporting the lot are therefore considered to be grossly stable under normal conditions and with proper maintenance. However, the surficial fill portions of the slope appear to be subject to creep. 'Surface Drainage Conditions I The pad is relatively flat and no evidence of erosive discharge onto the rear slope was noted. Changes to site drainage will result from construction of proposed improvements. Such must be intercepted, controlled and discharged by appropriate engineering design. Groundwater No groundwater was observed during our drilling. However, groundwater could occur as localized perched groundwater at the fill/bedrock contact. Groundwater is not anticipated to adversely affect the proposed development provided proper subsurface and surface drainage is incorporated into design and construction, where required. Seismic Considerations Published Studies One of the principles of seismic analyses and prediction is the premise that earthquakes are more likely to occur on geologically younger faults, and less likely to occur on older faults. For many years studies have described faults with Holocene movement (within the last 11,000 years) as "Active", and faults with documented Pleistocene movement (within the last 1.6 million years) and with undetermined Holocene movement as "Potentially Active". Informally, many studies have described faults documented to have no Holocene movement as "Inactive". Recent geologic and seismic publications are attempting to clarify the nomenclature describing faults to more accurately represent the potential affects from earthquakes. Reports by the California Division of Mines and Geology indicate faults with documented Holocene or Historic (within the last 200 years) movement should be considered Active. I September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 5 However, Potentially Active faults are more appropriately characterized in terms of the last period of documented movement. The Fault Activity Map of California (Jennings, C.W.; 1994) defines four categories for onshore Potentially Active faults. The categories are associated with the time of the last displacement evidenced on a given fault and are summarized in Table 1. Table 1, Definitions of Fault :Activity in California Activity Category Recency of Movement Active Historic Within the last 200 years Holocene Within the last 11,000 years Late Quaternary Within the last 700,000 years Potentially Quaternary Within the last 1.6 million years Active Late Cenozoic Possibly within the last 1.6 million years Pre -Quaternary Before the last 1.6 million years It is important to note these categories embrace all Pre -Holocene faults as Potentially Active, and provide no methodology to designate a given fault as "Inactive". Although the likelihood of an earthquake or movement to occur on a given fault significantly decreases with inactivity over geologic time, the potential for such events to occur on any fault cannot be eliminated within the current level of understanding. Local and Regional Faults The closest published active fault to the site is the offshore extension of the Newport -Inglewood Fault Zone, approximately 2.8 miles west-southwest, (Blake, T.F., 2000, CGS 2002). Other active faults in the vicinity of the site include the San Joaquin Hills approximately4.0 miles beneath the site, the Palos Verdes Fault approximately 16.4 miles southwest, the Coronado Bank Fault, approximately 20.8 miles southwest, and the San Andreas Fault, approximately 52.7 miles to the northeast. The offshore portion of the Newport -Inglewood Fault zone is indicated in published reports as being a Potentially Active and Quaternary fault, (Jennings, C.W.; 1994). This interpretation is not universally shared, as this portion of the Newport -Inglewood Fault is included as a potential seismic source in the computer programs utilized to model ground motions for this study, (Blake, T.F.; 2000). Given the present level of understanding of this offshore structure it is, in our opinion, appropriate to include this portion of the fault as a causative seismic feature. The California Geological Survey updated the Fault Parameters and Earthquake Catalog for the probabilistic Seismic Hazards Maps, (Cao, T., et al., 2002). This update included the addition of L' the "San Joaquin Hills" blind thrust fault, modeled to exist from Newport Beach to Dana Point, and ramping up inland to the Irvine area, and essentially underlying the site. Earthquakes of significant magnitude (M6.6) are presently postulated for this structure, and with the fault's September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 6 location beneath the site, it is calculated as the most significant seismic source to affect the property. Ground Motion Analyses The potential ground motions from earthquakes that could impact the sites were analyzed through probabilistic methods. The probabilistic method considers the regional seismic history and the slip rates of faults within a 100-mile radius of the subject site. Utilizing attenuation relationships (Bozorgnia, et al.; 1999, unconstrained/pleist. soil), one can estimate the ground motion history of the site and attempt to predict the probability of future accelerations within a given period of time. The study indicates the maximum site acceleration from 1800 to 2004 was approximately 0.21 g and occurred during a magnitude 6.3 Long Beach Earthquake 10.7 miles from the site on March 11, 1933. For the purposes of prediction and design, the peak acceleration with a 10 percent probability of exceedance in 50 years is deterinined to range from 0.40g to 0.46g. Secondary Seismic Hazards Review of the Seismic Hazards Zones Map (CDMG, 1998) for the Laguna Beach Quadrangle, Figure 2, indicates the site is not located within a zone of required investigation for liquefaction or for earthquake -induced landsliding. These results are in keeping with the findings of our study. j Other secondary seismic hazards to the site include deep rupture and shallow ground cracking, liquefaction, and settlement. The potential for shallow ground cracking to occur during an earthquake is a possibility at any site, but does not pose a significant hazard to site development. The potential for seismically induced surface fault rupture or settlement to occur is also f considered remote for the site. CONCLUSIONS 1. The proposed residence and improvements at the subject site are considered geotechnically feasible and safe providing recommendations herein are integrated into design, construction, and long term maintenance. Proposed construction should not affect adjacent properties providing appropriate construction methods and care are utilized during construction.. 2. The site is underlain at moderately shallow depth by bedrock strata which is overlain by engineered fill deposits consisting of clayey silt. Where unweathered, the fill deposits are medium stiff and are suitable to support proposed structural improvements. Laboratory j testing indicates that the fill deposits have a medium expansion potential, very severe j J corrosion potential to buried metals, and severe concentration of soluble sulfates. I � Ll l� 3 September 21, 2006 Project No:. 71665-00 Report No: 06-5866 F Page No: 7 3. GMU (2005) indicates the site and slope at the rear of the property should remain grossly stable under normal conditions and with proper maintenance. The rear slope will be affected by creep but should not adversely affect proposed improvements providing appropriate foundation design. 4. No groundwater was reported for the site. However, groundwater could occur intermittently at depth, and possibly perched at the fill/bedrock contact. Subsurface water is not anticipated to be a construction constraint. 5. Future surface discharge is to be controlled by engineered design. 6. The proposed residence should be supported on conventional foundations and retaining walls supported in fill. Improvements near top of slope, such as the swimming pool/spa, should be designed on deepened footings/caissons supported the beneath the creep zone. Site Preparation and Grading 1. General All grading should be performed in accordance with the Standard Grading Specifications in Appendix D. Grading will include excavation necessary to construct the residence basement; new pool/spa profile and/or cuts and fill to construct design grades. Remedial grading is recommended to include overexcavation of disturbed or dry surface fill in locations of proposed fills or hardscape improvements. The depth of overexcavation is anticipated to be 2+ feet below existing grade; however, locally deeper removals may be required pending review by the geologist during grading. All over -excavation and recompaction should be observed and approved in writing by a representative of this firm. 2. Removal of Existing Improvements Any existing vegetation and/or construction/demolition and irrigation debris should be removed and disposed of offsite. 3. Compaction Standard All onsite soil materials are anticipated to be suitable for re -use as compacted fill. Such materials should be placed at 140 percent of optimum moisture content and compacted under the observation and testing of the soil engineer to at least 90 percent of the maximum dry density as determined by ASTM D 1557-91. r 1 September 21, 2006 Project No: 71665-00 Report No: 06.5866 Page No: 8 4. Construction Slopes 1 Temporary construction slopes exposing fill materials may be constructed vertically to 5 feet, with higher slopes laidback at 1:1 (horizontal:vertical) pending field review by the geologist during grading. Structural Design of Foundations and Slabs Laboratory test results indicate that the surface soils exhibit a medium expansion potential. The following recommendations for foundation design are therefore considered preliminary pending additional laboratory testing of representative fill materials during grading. We recommend that the foundation and slabs be designed to resist the effects of expansive soils in accordance with Section 1815 of the 2001 California Building Code. Foundations and slabs should be designed for the intended use and loading by the Structural Engineer. The design should consider the expansion potential of the subgrade soils and other appropriate soil related criteria. Although there is no known economical method of totally preventing movement due to expansive soils, current state -of -the -practice in the Southern California area dictates substantial reinforcement, slab thickening, moisture barriers, and pre-soaking of subgrade soils as methods of minimizing the effects of expansive soils. Reasonable mitigation of expansive soil effects is considered feasible from a geotechnical viewpoint utilizing such methods, although it is noted that some future distress cannot be precluded when building on expansive soils. Our recommendations are considered to be generally consistent with the standards of practice. They are based on both analytical methods and empirical methods derived from experience with similar geotechnical conditions. These recommendations are considered the minimum necessary for the likely soil conditions and are not intended to supersede the design of the Structural Engineer or criteria of governing agencies. Structural Design Pertaining to Soil Creep It is generally accepted that soil creep is a surficial slope instability condition which is progressive in character and caused in this climatic environment by weathering expansion and contraction of sloping earth materials under the influence of moisture changes and gravity. The potential for structural distress of shallow foundation systems placed in or adjacent to creeping materials is high, as the creep process removes downslope support for conventional footings. Soil creep will effect those portions of the lot on or adjacent to the slopes. Potential distress associates with creep -induced foundation deformations should be anticipated and minimized with appreciate design which considers that most of the downslope movement of creep -prone materials occur in the first 10± feet of depth of sloping earth material. September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 9 Additionally, deformations caused by movement cannot be entirely precluded, and it is the intent of these recommendations only to minimize their perception. Other design considerations which will minimize the perception of movement include use of flexible surfacing materials rather than frangible materials such as tile, brick and stucco. Conventional Footings and Slab -on -Grade Conventional foundations and slabs -on -grade should be designed in accordance with Section 1815 of the 2001 California Building Code utilizing an effective plasticity index of 40. 1 The allowable bearing capacity of conventional footings having a minimum width of 15 inches and founded a minimum of 24 inches into firm compacted fill should not exceed 1500 pounds per square foot. This value may be increased 20 percent for each additional foot of width or 1 % depth, up to a maximum of 3000 pounds per square foot. This value may also be increased by one-third for short-term conditions such as wind or seismic loading. Settlement of footings is r anticipated to be on the order of 3/4 inch total and 1/2 inch differential. Lateral loads may be resisted by passive pressure forces developed within compacted fill in front of the footings and by friction acting at the base of the footings. Passive pressure forces may be computed using an equivalent fluid density of 150 pounds per cubic foot, not to exceed a total pressure of 1500 pounds per square foot. Frictional resistance maybe computed assuming a coefficient of 0.25. The minimum recommended slab thickness is 5 inches, and the maximum recommended reinforcing is No. 4 bars at 1.2 inches, placed in both directions. Slabs should be underlain by 4 inches of gravel. In moisture sensitive areas, slabs should also be underlain by a 15-mil thick vapor retarder/barrier in accordance with the requirements of ASTM E:1745 and E:1643. All subgrade materials should be geotechnically approved prior to placing gravel. Moisture Content of Slab Subgrade Soils Presoaking of slab subgrade soils is required prior to construction of slabs. We recommend that subgrade soils be soaked to at least 140 percent of optimum moisture content to a minimum depth of 18 inches prior to placing gravel. Footing Reinforcements To resist adverse effects of tension cracking due to seismic shaking and expansive soils, a minimum of two No, 5 bars should be placed at the top and bottom of continuous footings. September 21, 2006 Project No: 71665-00 r, Report No: 06-5866 Page No: 10 Caissons Caisson utilized for support of the pool and spa should be twenty-four inch diameter and embedded a minimum of 10 feet into competent fill below the anticipated creep zone. Caissons maybe designed for a dead plus live load end bearing value of 4500 pounds per square foot and skin friction of 250 pounds per square foot for fill below the creep zone only. These values may be increased by one-third for wind and seismic forces. Lateral resistance may be computed utilizing 150 pounds per square foot per foot of depth, acting on a tributary area of twice the caisson diameter. Settlement is anticipated to be less than 3/4 inch. A minimum 24-inch diameter caisson is required in order to verify proper cleanout by the contractor and to allow visual observation and confirmation by the engineering geologist. Caisson design in the creep zone should recognize that soil creep movement will remove downslope support. Caissons adjacent to the rear slope should be design to resist lateral pressure loading of 75 pounds per cubic foot equivalent fluid pressure to a depth of 10+ feet at the edge of slope. Passive resistance may be taken only below the potential creep zone. Final caisson design and locations should be accomplished by joint consultation between the geotechnical engineer and the structural engineer in order to develop an effective design. Design of Retaining Walls and Shorin 1. Structural Design of Retaining Walls Active pressure forces acting on walls retaining level imported granular backfill or compacted native backfill may be designed using an equivalent fluid densities of 35 and 75 pounds per cubic foot, respectively (refer to Figure 3 for backeut and backfill geometry). Wall rotation on the order of 0.1 percent of the wall height should be anticipated and considered in design of walls and adjacent hardscaping. Restrained walls should be designed for a pressure of 50 percent greater than that for unrestrained walls. 2. Subdrains The drainage scheme depicted on Figure 3, or an approved alternative, should be used to control seepage forces behind retaining walls. 3. Wall Excavations Wall excavations will require slope laybacks of 1:1 (horizontal:vertical) in fill where higher than 5 feet. r` September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 11 4. Shoring Shoring should be designed in accordance with the retaining wall and foundation. recommendations presented above. In addition, the design and construction should consider that onsite soils may have zones which are prone to caving and/or settlement. Vibratory techniques for placement of piles or steel sheet lagging should not be utilized, as damage to adjoining property improvements may otherwise occur. It is the contractor's responsibility to develop appropriate means and methods of construction to avoid damage to adjacent properties. Casing of excavations is likely to be necessary. If temporary shoring elements are to be removed, the builder and homeowner must be aware that such removal could result in settlement and possible damage to improvements on the adjacent property. The adjacent property owners must be advised of the risks and the builder should provide arrangements to repair any possible damages. The contractor should also recognize the risk of leaving voids during removal of shoring elements. Lagging plates and piles should therefore be removed slowly and the voids created should be filled immediately. Consideration should be given to continuously injecting grout at the base of the piles and plates as they are being removed to fill the resultant voids. Hardscape Design and Construction Hardscape design should anticipate the potential for movement from the shrinkage and swelling of expansive soils. Design of hardscape elements, including patios, driveways, fences or garden walls, should therefore utilize the recommendations herein to limit distress to improvements. Planters located adjacent to principle foundation elements should be sealed and drained; this is especially important if located upon retaining wall backfills. Concrete flatwork should be divided into as nearly square panels as possible. Joints should be provided at maximum 6 feet intervals to give articulation to the concrete panels. Landscaping and planters adjacent to concrete flatwork should be designed in such a manner as to direct drainage away from concrete areas to approved outlets. Flatwork elements should be a minimum 5 inches thick (actual) and reinforced with No. 4 bars 16 inches on center both ways. A 12-inch reinforced thickened edge should also be utilized for significant elements. Subgrade presaturation to 140 percent of optimum is recommended to a depth of 18 inches. Footings for patio areas as well as masonry walls located near the top of slope at the rear property boundary should conform to slope setback recommendations presented below. I September 21, 2006 Project No: 71665-00 Report No: 06-5866 Page No: 12 It is recommended that low water need plants be selected for general landscaping purposes to minimize irrigation requirements and consequent saturation of underlying soils, All hardscape subgrade must be approved by the geotechnical consultant prior to placement of concrete. Seismic Structural Design Based on the geotechnical data and location of the site on the Active Fault Near Sources Zones Map N-34 (ICBO, 1998, excluding the San Joaquin Hills Blind Thrust), the following seismic parameters for the 2001 CSC are provided: Seismic Design Criteria per 2001 CDC C Table Design Parameters 16-I Zone Factor Z = 0.40 16-J Soil Profile Type: SD 16-Q Seismic Coefficient Ca = 0.51 16-R Seismic Coefficient Cv = 0.91 16-5* Near Source Factor Na = 1.2 16-T* Near Source Factor Nv = 1 A 16-U Seismic Source Type: B *Closest distance to seismic source = 3.3 km The seismic. parameters considering the San Joaquin Blind Thrust are provided in the following table. San Joaquin BAT'Seismic Design Criteria Table Design Parameters 16-1 Zone Factor Z = 0.40 16-J Soil Profile Type: SD 16-Q Seismic Coefficient Ca = 0.57 16-R Seismic Coefficient Cv = 1.02 Near Source Factor Na =1.3 16-T* Near Source Factor Nv = 1.6 16-U Seismic Source Type: B *Closest distance to seismic source = <2 km Structural Design of Swimming Pool and Spa Active pressure forces acting on the pool and spa walls should be designed using an equivalent fluid density of 75 pounds per cubic foot for onsite fill. September 21, 2006 Project No: 71665-00 Report No: 06-5866 T Page No: 13 Surcharge loads, both topographic and structural, should be considered by the structural engineer. Lateral loads maybe resisted utilizing criteria presented for conventional footings in fill deposits. Slone Setback The bottom of all caissons should be set back a minimum of 10 feet from the anticipated base of the creep zone as depicted on Figure 5. The depth of creep may be assumed to be 10+ feet for design purposes and should be field evaluated as conditions become exposed during excavation. Concrete Laboratory test results indicate onsite derived soils have a severe soluble sulfate content. It is recommended that a concrete expert be retained to design an appropriate concrete mix to address soil soluble sulfate content, as well as the structural requirements. In lieu of retaining a concrete expert, it is conservatively recommended that the 2001 California Building Code, 19-A-4 be utilized, which requires Type V cement, a maximum water cement ratio of 0.45, and a minimum % compressive strength of 4500 psi. Finished Grade and Surface Drainage All finish grades should assure that no water ponds in the vicinity of footings or the rear slope. All discharge conducted away from the house and slopes and offsite in a nonerosive manner as specified by the project civil engineer or landscape architect. Maintenance of drainage, landscaping, and irrigation systems is required to ensure long-term stability of grading hillside property. Guidelines for maintenance of graded sites are presented in Appendix E. Utility Trench Backfill Utility trench backfill should be placed in accordance with Appendix F. Utility Trench Backfill Guidelines. It is the owners and contractors responsibility to inform subcontractors of these requirements and to notify Geofirm when backfill placement is to begin. In addition, the owner or his representative should prepared a map on an ongoing basis which depicts the location of all underground utilities for inclusion in the as -built geotechnical report. Foundation flan Review In order to help assure conformance with recommendations of this report and as a condition of I the use of this report, the undersigned should review final foundation plans and specifications I prior to submission of such to the building official for issuance of permits. Such review is to be performed only for the limited purpose of checking for conformance with the design concept and the information provided herein. This review shall not include review of theaccuracy or completeness of details, such as quantities, dimensions, weights or gauges, fabrication processes, H jl E September 21, 2006 Project No: 71665-00 Report No: 06-5866 f Page No: 14 construction means or methods, coordination of the work with other trades or construction safety precautions, all of which are the sole responsibility of the Contractor. Geofirm's review shall be conducted with reasonable promptness while allowing sufficient time in our judgment to permit adequate review. Review of a specific item shall not indicate that Geofirm has reviewed the entire system of which the item is a component. Geofirm shall not be responsible for any deviation from the Construction Documents not brought to our attention in writing by the Contractor. Geofirm shall not be required to review partial submissions or those for which submissions of correlated items have not been received. Observation and Testing As a condition of the use of this report, it is required that geotechnical construction observation will be conducted by Geofirm to verify proper removal of unsuitable materials, that foundation excavations are clean and founded in competent material, to test for proper moisture content and J proper degree of compaction of fill, to test and observe placement of wall and trench backfill materials, and to confirm design assumptions. j A Geofirm representative shall visit the site at intervals appropriate to the stage of construction, as notified by the Contractor, in order to observe the progress and quality of the work completed by the Contractor. Such visits and observation are not intended to be an exhaustive check or a detailed inspection of the Contractor's work but rather are to allow Geofinn, as an experienced professional, to become generally familiar with the work in progress and to determine, in general, if the work is proceeding in accordance with the recommendations of this report. d Geofirm shall not supervise, direct, or have control over the Contractor's work nor have any responsibility for the construction means, methods, techniques, sequences, or procedures selected by the Contractor nor the Contractor's safety precautions or programs in connection with the work. These rights and responsibilities are solely those of the Contractor. Geofirm shall not be responsible for any acts or omission of the Contractor, subcontractor, any entity performing any portion of the work, or any agents or employees of any of them. Geofirm does not guarantee the performance of the Contractor and shall not be responsible for the Contractor's failure to perform its work in accordance with the Contractor documents or any applicable law, codes, rules or regulations. These observations are beyond the scope of this investigation and budget and are conducted on a time and material basis. The responsibility for timely notification of the start of construction and ongoing geotechnically involved phases of construction is that of the owner and his contractor. Typically, at least 24 hours notice is required. September 21, 2006 I Jobsite Safety Project No: 71665-00 Report No; 06-5866 Page No: 15 Neither the professional activities of Geofirm, nor the presence of Geofirm''s employees and subconsultants at a construction/project site, shall relieve the General Contractor of its obligations, duties and responsibilities including, but not limited to, construction means, methods, sequence, techniques or procedures necessary for performing, superintending and coordination the work in accordance with the contract documents and any health or safety precautions required by any regulatory agencies. Geofirm and its personnel have no authority to exercise any control over any construction contractor or its employees in connection with their work or any health or safety programs or procedures. The General Contractor shall be solely responsible for jobsite safety. LIMITATIONS This investigation has been conducted in accordance with generally accepted practice in the F engineering geologic and soils engineering field. No further warranty is offered or implied. I Conclusions and recommendations presented are based on subsurface conditions encountered and are not meant to imply a control of nature. As site geotechnical conditions may alter with time, the recommendations presented herein are considered valid for a time period of one year from the report date. The recommendations are also specific to the current proposed development. Changes in proposed land use or development may require supplemental , investigation or recommendations. Also, independent use of this report in any form cannot be approved unless specific written verification of the applicability of the recommendations is obtained from this firm. Thank you for this opportunity to be of service. If you have any questions, please contact this office. Respectfully submitted, WOW FIMSI A. Trigg, Bering Geologist, E.4.1619 Registration Expires 12-31 KAT:HHR:fp Distribution: (5) to Addressee Hannes H. Richter, P.E. Geotechnical Engineer, G.E. 717 Registration Expires 3-31-08 Date Signed: �/ b2 -1 o6 i H i Typical •' •. •' ' Geotextile Filter Fabric Retaining Select Xoncohosive' .' Wall ... Granular Baekfill•'•'• H 4i - 112 H Limit of Wall Excavation ' Geotextile Filter Fabric •' • 8" Lap ti•{•ti ti Li'L Single -sized 1/2"-3/4" Drain Rock r� 4" Perforated Plastic Collector - Pipe, (Below Slab Elevation) Notes: This system consists of a geotextile fabric -wrapped gravel envelope. Collection is with a fl- inch diameter perforated plastic pipe embedded in the gravel envelope and tied to a 4-inch diameter non -perforated plastic pipe which discharges at convenient locations. The outlet pipe should be placed such that the flow gradient is not less than 2.0 percent. The geotextile fabric -wrapped gravel envelope should be placed at a similar gradient All drain pipes should be Schedule 40 PVC or ABS SDR-35. Perforations may be either bored 1/4- inch diameter holes or 3/16-inch slots placed on the bottom one-third of the pipe perimeter. If the pipe is to be bored, a minimum of 10 holes should be uniformly placed per foot of length. If slots are made, they should not exceed 2-1/2 inches in length and should not be closer than 2 inches. Total length of slots should not be less than 50 percent of the pipe length and should be uniformly spaced. The fabric pore spaces should not exceed equivalent 30 mesh openings or be less than equivalent 100 mesh openings. The fabric should be placed such that a minimum lap of 8-inches exists at all splices. n Typical Retaining Wall Subdrain Detail �."-�,�^•�:-��`.�-iw=ir�r-r-� JOBNO.: DATE: FIGURE: 71665-00 September 2006 3 't-t 10'I iEf / -- SEGMENTAL WALL /� I (EXISTING) ASUBDRAIN / (EXISTING) TYPICAL BEDDINC (GMU) T HORIZONTAL AND VERTICAL SCALE: 1 INCH = 20 FEET 0 20 40 FEET 1 PROPOSED r £ GRADE 15" Sz � ..7 y � �� f-• � i S _ i t SUBDRAIN (PROPOSED) FOR EXPLANATION REFER TO FIGURE 4 v \ LL w z 0 � w \ J w GEOTECHNICAL CROSS SECTION A -A' LOT 28a, TRACT 16456 CRYSTAL COVE NEWPORT BEACH, CALIFORNIA Project no.: Date: Figure: 71665-00 1 SEPTEMBER 2006 1 5 A -A' t tai3, } PROPOSED EXISTING ,` GRADE TOPOGRAPHIC PROFILE R <' t F3j 500 ; s 500 II II 480 I I 480 wEf w LL PROPERTY LINE w z CAISSON/RETAINING z z 460 \ WALL 460 Z 0 O Tm . \ W 440 \ 440 Tm TYPICAL , 420 BEDDING 420 (GMU) \ 400 400 HORIZONTAL AND VERTICAL SCALE: 1 INCH = 20 FEET GEOTECHNICAL CROSS SECTION B-B' 0 20 40 LOT 28a, TRACT 16456 CRYSTAL COVE FEET NEWPORT BEACH, CALIFORNIA FOR EXPLANATION Protectno.: Date: I Figure: REFER TO FIGURE 4 71665-00 1 SEPTEMBER 2006 6 APPENDIX A REFERENCES REFERENCES 1. Blake, T.F., 2000a, "BQSEARCH, Version 3.0b, A Computer Program for the Estimation of Peak Horizontal Acceleration from California Historical Earthquake Catalogs." 2. Blake, T.F., 2000b, "EQFAULT, Version 3.0b, A Computer Program for the Deterministic Prediction of Peak Horizontal Acceleration from 3-D Fault Sources" User's Manual" (Windows 95/98 Version). 3. Blake, T.F., 2000c, "FRISKP, Version 4.0, A Computer Program for the Probabilistic Estimation of Peak Acceleration and Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources, (Version 4.00)". 4. Blake, T.F., 2000d, "UBCSEIS, Version 1.03, A Computer Program for the Estimation of Uniform Building Code Coefficients Using 3.0 Fault Sources", (Windows 3.1 and Windows 95 Versions). 5. Bozorgnia, Y., Campbell, K.W., and Niazi, M. M., 1999, "Vertical Ground Motion: Characteristics, Relationship with Horizontal Component, and Building Code Implications", Proceedings of the SMIP99 Seminar on Utilization of Strong -Motion Data, pp. 23-49, dated September 15. 6. California Building Code, 2001 Edition. 7. California Division of Mines and Geology, 1973, "Geo-Environmental Maps of Orange County, California"; Preliminary Report 15. 8. California Division of Mines & Geology, 1976, "Geology and Engineering Geologic Aspects of the Laguna Beach Quadrangle, Orange County, California," Special Report 127. 9. California Division of Mines and Geology, 1997, "Guidelines for Evaluating and Mitigating Seismic Hazards in California," Special Publication 117. 10. California Division of Mines and Geology, 1998, "Seismic Hazards Zones Map, Laguna Beach Quadrangle" 11. GMU Geotechnical, Inc., 2005, "Report of Geotechnical Observation and Testing of Rough Grading, Portion of Lower Customs, Lots 112 through 119, Tentative Tract 15613, Crystal Cove, Newport Beach, Orange County, California," Project No. 03-90-10, dated July 22. 12. Grant et al, 1999, "Late Quaternary Uplift and Earthquake Potential of the San Joaquin Hills, South Los Angeles Basin, California." Geology, November 1999, V. 27, No. 11, P 1031-1034. 13. Jennings, Charles W., et al, 1994, "Fault Activity Map of California and Adjacent Areas," California Division of Mines and Geology, Geologic Data Map No. 6. 14. Leighton And Associates, Inc., 1999, "Preliminary Geotechnical Recommendations for Design of Post -Tensioned Slab Foundations for Support of Residential Structures and for Wine Cellar Walls, Crystal Cove, Tract 15586, Newport Coast, County of Orange, California", Project No. 1830019-33, dated June 18. 15. Martin, G.R. and Lew, M.; 1999, "Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in California", SCEC, dated March. 16. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Lienkaemper, J.J., McCrory, P.A., and Schwartz, D.P., 1996, "Probabilistic Seismic Hazard Assessment for the State of California", Department of Conservation, Division of Mines and Geology, DMG Open -File Report 96-08, USGS Open File Report 96-706. 17. Petersen, M.D., Beeby, D., Bryant, W., Cao, C., Cramer, C.H., Davis, J., Reichle, M.S., Saucedo, G., Tan, S., Taylor, G., Toppozada, T., Treiman, J., Wills, C., 1999; "Seismic Shaking Hazard Maps of California", Department of Conservation, Division of Mines and Geology, DMG Map Sheet 48. 18. Petersen, M.D., Toppozada, T.R., Cao, T., Cramer, C.H. Reichle, M.S., and Bryant, W.A., 2000, "Active Fault Near -Source Zones Within and Bordering the State of California for the 1997 Uniform Building Code", The Professional Journal of the Earthquake Engineering Research Institute, Earthquake Spectra, Volume 16, Number 1. 19. Petra Geotechnical Inc., 2002, "Geotechnical Investigation, Proposed Single -Family Residence, 2526 Riviera Drive, Lot 25 of Tract No. 2818, Irvine Cove, Laguna Beach, California", J.N. 446-01, dated June 10. 20. U.S.G.S., 2004, "Preliminary Digital Geologic Map of the Santa Ana 30' x 60' Quadrangle, Southern California", Version 2.0 . :�., i) r�.. �. Date(s) Logged: 7/31/2006 Method of Drilling: 8" HSA Logged By: JLH Drilling Company: 2R Drop: 30" LOCATION: Pool at rear of lot Weight(s): 140# Ground Elevation:± 486' A.M.S.L. c oa) BORING NO.: B-1 [ca)L U EY) a)o o� E o o Q Description Geologic CUD) cc) oo D co o0 U c o Attitudes 0 Engineered Fill (0 - 34') - Medium to light olive brown clayey SILT, slightly moist, dense, 2 scattered silicous bedrock clasts. 2 - 3 3 - 4 4 - 5 5 5 6 16 @ 5' - Increasingly darker brown. 6 - 21 34.8 68.0 8 8 - 9 9 _ 10 ' 10 10 - 11 1722 35.8 68.9 @ 11' - Brown clayey SILT; dense, uniform moisture (moist to 11 - 12 ' slightly moist), pervasive bedrock clasts. 12 - 13 • 13 - 14 • 14 - 15 ' 10 15 - 16 • 16 @ 15' Increased clay content, increased moisture. 16 - 17 24 34.7 77.0 17 - 18 ' 18 - 19 19- 20 2- 23 @ 20' Very dense clayey SILT; uniform, moist. 21 1 22 . 32 30.4 82.7 22 - ' 23 ' 23 - .24• 24- ' 25 ' 14 25 - 26 31 X @ 25' - Unoxidized clayey siltsone clasts in clayey SILT. . •27• 32 30.6 79.2 26 - 27 - • 28 .28 - . 29 ' - 29 - 30 ' 10 30 - 31 12 31 - 32 17 37.7 74.6 32 - 33 ' 33 - 34--------------------------------------------------------------------------------------------------- •34 - . 35 • 20 BEDROCK (34 -43') 35 - •36 50 @ ±35' -Monterey Formation- Medium brown siltstone shale; hard, 36 - 26.5 81.4 silicous cemented beds, yellow sandstone interbeds. 37 -37- .38. 38 - • 39 39 - 40 .. 40 ,. Project No.: 71665-00 LOG OF BORING Figure No.: b1 Boring Log 1.xls 9/14/2006 Stoney-miiiier consultants, Inc. Dates) Logged: 7/31/06 Method of Drilling: 8" HSA Logged By: JLH Drilling Company: 2R Drop: 30" LOCATION: Pool at rear of lot Weight(s): 140# Ground Elevation:± 486' A.M.S,L. — 2:U ❑ CL BORING NO.: B-1 r. E a) Continued v o-6 E o o a Description Geologic o ❑ cn U m D U) m U ❑ Attitudes ❑ 40 - 20 @ 40'continued- Monterey Formation• Medium brown siltstone 40 41 40 shale; hard, silicous cemented beds, yellow sandstone interbeds, 41 42 - 45 32.8 83.E : 42 43 - 43 Total Depth = 43' 44 - 44 No Groundwater 45 - 45 Backfilled 7/31/06 46 - 46 47 - 47 48 - 48 49 - 49 50- •50• 51 - 51 52 - 52 - 53 - 53 54 - 54 55 - 55 56 - 56 57 - 57 58 - 58 59 - 59 60 - 60 61 - 61 62- 62• 63 - 63 64 64 65 - 65 - 66 - 66• 67- 67• 68 - 68 69 - 69 70 - 70 71 - 71 72 - 72 , 73 - 73 74 - 74 75 - 75 , 76 - 76 77 77 78 - 78 79 79 80 •• 80 ., Project No.: 71666-00 LOG OF BORING Figure No,: b2 Boring Log 1,xls 9/14/2006 Money-willler Consultants, Inc. Date(s) Logged: 7/31/2006 Method of Drilling: 8" HSA Logged By: JLH Drilling Company: 2R Drop: 30" LOCATION: North side lot in proposed patio deck Weight(s): 140# Ground Elevation: 495' A.M.S.L. c _ p� n CORING NO.: B-2 N W U z, o o o ° Description Geologic 0 rn U m cn M 2E U c Q Attitudes 0 0 0 Engineered Fill (0 - 21') 1 Light brown SILT, stiff, shale clasts, dry in upper 2', slightly moist 1 2 below. 2 3 - 3 4 4 5 12 - 5 17 @ 6' Unoxidized siitstone clast in slightly moist clayey SILT matrix, 6 6 7 29 29.4 80.3 hard. 7 8 8 9 9 10 ' 11 .10 11 , 20 11 12 25 22.8 87.3 - 12 13 • - 13 14 • 14 ' 15 ' 10 - 15 . 16 , 16 -16 21 32.6 79.6 @ 16' Increased clay in siitstone clasts, slightly moist, very stiff 17 - 17 18 • 18 19• -19 ' 20 ' 10 20 21. __-____ 22 K -------^- ----- --------------------------------------------------- 21 • 22 • 26 37.7 75.5 BEDROCK (21 - 28') - 22 @ 21' Monterey Formation - Medium gray -brown fissile 23 ' SILTSTONE, hard where cemented, thinly bedded, iron stained ' 23 • 24 • beds. - 24 • 25 • 25 25 • 26 , 50/5° 35.8 73.7 @ 25' Medium gray silicified SILTSTONE, very hard, thinly 26 bedded, moderately fractured, dipping at a shallow angle. 27 - 27 29 29 Total Depth - 28' . No Groundwater 80 - 30 Backfilled 7/31/2006 • 31 - 31 32 • - 32 33 • - 33 34 • - 34 35 • - 35 36 • - 36 37 • - 37 •38• -38 •39• -39 40 • 40 Project No.: 71665-00 L®G ®F®F29NG Figure No.: b3 Boring Log 2.xls 9/15/2006 Geofirm Dates) Logged: 7/31/2006 Method of Drilling: 8" HSA Logged By: JLH Drilling Company: 2R " 30 Drop: p:Welg0" LOCATION: Driveway front of lot' 140# Ground Elevation: 502' A.M.S.L. c � E p a. BORING NO.: B-3 15 'J a _ N � E N to : Description Geologic a ® o cn cv o� 00 � 07 m o® U c o I. Attitudes o 0 0 1 Engineered Fill (0 - 26.5') - 1 Medium red -brown SILT, stiff, slightly moist, dry in upper 2', 2 bedrock clasts of shale pervasive. 2 3 3 4 -4 5 14 5 6 17 - 6 31 34.2 79.8 @ 6' Medium gray brown clayey SILT; very stiff, slightly moist, 7 well compacted, scattered siliceous shale clasts. 7 8 8 9 9 ' 10.. 16 10 11 . 31 X - 11 41 37.2 75.7 @11' Uniformly moist, very stiff to hard. •12• -12 13 • - 13 14 • -14 15 ' 11 - 15 16 . 14 - 16 17 33.5 79.9 @16' Uniformly moist, stiff. •17• -17 18 • - 18 19• -19 20 12 @ 20' Uniformly moist, very stiff. - 20 .21 20 - 21 22 21 35.0 79.3 - 22 •23• -23 •24• .24 ' 25 ' 14 - 25 • 26 • 17 36.3 77.0 - 26 ------- 50/3" --- ---- ----- ----- --------------------- 27 ' BEDROCK (26.5 - 31') - 27 28 • @ 26.5' Monterey Formation, Medium red -brown clayey - 28 29 • SILTSTONE, hard, fissile, thinly bedded. 29 • 30 • - 30 50 37.6 73.6 @30' - Medium red -brown to gray SILTSTONE; hard, fissile. 31 -31 Total Depth = 31' 32 32 No groundwater Backfilled 7/31/06 34 • - 34 35 • - 35 •36• -36 •37• -37 •38• -38 •39• -39 -40. 40• Project No.: 71665-00 LOG OF BORING Figure No.: b4 Boring Log 3.xis 9/15/2006 Geofirm Dates) Logged: 7/31/2006 Method of Drilling: 8" HSA Logged By: JLH Drilling Company: 2R Drop: 30" LOCATION: ±10' North of Southerly Property line Weight(s): 140# Ground Elevation: 493' A.M.S.L. O Q o a BORING NO.: B-4 ID E o.. N E Y N = 0- = Description Geologic ..0 5- a)o ® ro cn U o Cn c M = cn m O o 2 v E o a) Attitudes 1 o .o, -o Engineered Fill (0 - 23') - 1 1 Medium brown SILT; dry in upper 2', scattered siltstone bedrock 2 • clasts, slightly moist below 2', stiff to very stiff. 2 3 3 4 4 5 14 5 6 17 6 .7 31 34.2 76.0 -7 8 8 g - 9 • 10 • 16 10 11 17 11 12 , 24 28.6 82.1 - 12 13 • 13 . 14 . - 14 •15- 15 -15 16- 30 -16 17 - 25 35.4 74.7 -17 18 . - 18 19 , - 19 20 19 @ 20' Same moisture, stiff clayey SILT, shale clasts. - 20 , - 21 . 2z . 28 37.1 73.4 22 •23---------------------------------------------------------------------------------------- BEDROCK (23' - 26.5') -23 24 ' @ 23' Monterey Formation, fissile SILTSTONE shale; hard, - 24 • 25 • 25 thinly bedded. - 25 26 38 2.4 Dist @26 Light brown concretionary bed, fractured. " 26 50/4" 27 . - 27 Total Depth 26.5' .Zg. No Groundwater -28 • 29 • Backfilied 7/31/06 - 29 • 30 • - 30 .31 , - 31 , 32 . - 32 33 • .33 •34• -34 •35• -35 •36• -36 , 37 . - 37 • 38 . 38 ,3g, -39 40 ,,,. „ 40 - Project No.: 71665-00 LOG OF BORING Figure No.: b5 Boring Log 4,xls 9/15/2006 Ge®firm APPENDIX C I. Field Exploration Procedures A. Field Exploration A truck -mounted hollow -stein flight auger rig with an 8-inch diameter auger was utilized to expose subsurface soils. Core samples were obtained at regular intervals as the drilling advanced. Bulk or disaggregated samples were also obtained. B. Sam 1. Core Samples Core samples of subsurface materials were obtained by driving a steel barrel drive sampler. Samplers were driven utilizing 140 pound weight that is raised and permitted to fall 30-inches utilizing an automatic trip system. The sampler has an outside diameter of 3.0-inches and is lined with a series of 1-inch high brass rings having an inside diameter of 2.43- inches. A drive shoe is placed on the tip of the sampler to hold the liners in place during sampling. The samples were removed from the sample barrel in the brass rings, placed in moisture tight containers, and transported to the laboratory for testing. Records of the number of blows required to affect each 6-inches of penetration were made, as indicated on the boring log in Appendix B. 2. Disag regated Samples Disaggregated soil samples were obtained at the surface from the spoils pile as the drilling advanced. These soils were bagged and transported to our laboratory. II. Laboratory Testing Procedures A. Moisture and Densily Tests Dry unit weights and field moisture contents were determined for core specimens j obtained from the test sampler by measuring the volume and weight of the core specimens. Moisture determinations were made in accordance with ASTM test methods. The results are summarized on the Boring Logs, Appendix B. B. Corrosion Test Results A corrosivity series of tests were performed on two specimens of soil. The testing includes a determination of sulfate content in accordance with California test method 417, a pH determination in accordance with ASTM D 4972, and a minimum resistivity determination in accordance with California test method 643. The test results are presented below. Sample Designation - B-2 @ 0-4' B-4 @ 10-15' pH - 7.4 7.5 Soluble Sulfate - 2,517 mg/kg 1,520 mg/kg Minimum Resistivity - 480 ohm -cm 520 ohm -cm (saturated) C. Expansion Index Test An expansion index test was performed in accordance with UBC Standard No. 29-2. The results of the test are tabulated below: Sample Desiguation Boring 2 Pa 0-4' Boring 4 @a, 10-15' Expansion Index - 60 61 Expansion Classification - Medium Medium D. Atterberg Limits Determination Atterberg Limits were determined in accordance with ASTM D 4318. The results are tabulated below. Sample Liquid Plastic Plasticity Soil Designation Limit Limit Index Classification B-4 @ 10-15' 74 38 36 MH E. Maximum Densit a�ptimum Moisture Determinations Optimum moisture and maximum density were determined in accordance with Test Designation ASTM D 1557. These results are tabulated below: Optimum Maximum Moisture Content Dry Density (% ) (Pefl 31.0 84.0 APPENDIX D STANDARD GRADING SPECIFICATIONS APPENDIX D STANDARD GRADING SPECIFICATIONS GENERAL These Guidelines present the usual and minimum requirements for grading operations observed and tested by Geofirm, or its designated representative. No deviation from these guidelines will be allowed, except where specifically superseded in the geotechnical report signed by a registered geotechnical engineer. The placement, spreading, mixing, watering and compaction of the fills in strict accordance with these guidelines shall be the sole responsibility of the contractor. The construction, excavation, and placement of fill shall be under the direct observation of the geotechnical engineer or any person or persons employed by the licensed geotechnical engineer signing the soils report. If unsatisfactory soil -related conditions exist, the geotechnical engineer shall have the authority to reject the compacted fill ground and, if necessary, excavation equipment will be shut down to permit completion of compaction. Conformance with these specifications will be discussed in the final report issued by the geotechnical engineer. All brush, vegetation and other deleterious material such as rubbish shall be collected, piled and removed from the site prior to placing fill, leaving the site clear and free from objectionable material. Soil, alluvium, or rock materials determined by the geotechnical engineer as being unsuitable for placement in compacted fills shall be removed from the site. Any material incorporated as part of a compacted fill must be approved by the geotechnical engineer. The surface shall then be plowed or scarified to a minimum depth of 6 inches until the surface is free from uneven features that would tend to prevent uniform compaction by the equipment used. After the area to receive fill has been cleared and scarified, it shall be diced or bladed by the contractor until it is uniform and free from large clods, brought to the proper moisture content, and compacted to minimum requirements. If the scarified zone is greater than 12 inches in depth, the excess shall be removed and placed in lifts restricted to 6 inches. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipe lines or others not located prior to grading are to be removed or treated in a manner prescribed by the geotechnical engineer. MATERIALS Materials for compacted fill shall consist of materials approved by the geotechnical engineer. These materials may be excavated from the cut area or imported from other approved sources, and soils from one or more sources may be blended. Fill soils shall be free from organic vegetable matter and other unsuitable substances. Normally, the material shall contain no rocks or hard lumps greater than 6 inches in size and shall contain at least 50 percent of material smaller than 1/4-inch in size. Materials greater than 4 inches in size shall be placed so that they are completely surrounded by compacted fines; no nesting of rocks shall be permitted. No material of a perishable, spongy, or otherwise of an unsuitable nature shall be used in the fill ' soils. Representative samples of materials to be utilized as compacted fill shall be analyzed in the laboratory by the geotechnical engineer to determine their physical properties. If any material other than that previously tested is encountered during grading, the appropriate analysis of this material shall be conducted by the geotechnical engineer as soon as possible. PLACING, SPREADING, AND COMPACTING PILL MATERIAL The material used in the compacting process shall be evenly spread, watered, processed and compacted in thin lifts not to exceed 6 inches in thickness to obtain a uniformly dense layer. When the moisture content of the fill material is below that specified by the geotechnical engineer, water shall be added by the contractor until the moisture content is near optimum as specified. When the moisture content of the fill material is above that specified by the geotechnical engineer, the fill material shall be aerated by the contractor by blading, mixing, or other satisfactory methods until the moisture content is near optimum as specified. After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted to 90 percent of the maximum laboratory density in compliance with ASTM D: 1557 (five layers). Compaction shall be accomplished by sheepsfoot rollers, vibratory rollers, multiple -wheel pneumatic -tired rollers, or other types of acceptable compacting equipment. Equipment shall be of such design that it will be able to compact the fill to the specified density. Compaction shall be continuous over the entire area and the equipment shall make sufficient passes to obtain the desired density uniformly. A minimum relative compaction of 90 percent out to the finished slope face of all fill slopes will be required. Compacting of the slopes shall be accomplished by backrolling the slopes in increments of 2 to 5 feet in elevation gain or by overbuilding and cutting back to the compacted inner core, or by any other procedure which produces the required compaction. GRADING OBSERVATIONS AND TESTING The geotechnical engineer shall observe and test the placement of fill during the grading process and will file a written report upon completion of grading stating his observations as to compliance with these specifications. One density test shall be required for each 2 vertical feet of fill placed, or one for each 1,000 cubic yards of fill, whichever requires the greater number of tests. Any cleanouts and processed ground to receive fill must be observed by the geotechnical engineer and/or engineering geologist prior to any fill placement. The contractor shall notify the ` geotechnical engineer when these areas are ready for observation. I� L _.� PROTECTION OF WORK During the grading process and prior to the complete construction of permanent drainage controls, it shall be the responsibility of the contractor to provide good drainage and prevent ponding of water and damage to adjoining properties or to finished work on the site. After the geotechnical engineer has terminated his observations and tests of the completed grading, no further excavations and/or filling shall be performed without the approval of the geotechnical engineer, if it is to be subject to the recommendations of this report. ����►.1 .. ; . � . �, r' •. '1� � "1� MAINTENANCE OF GRADED SITES Sites graded in hillsides require maintenance and repair of slopes and drainage. The City of Los Angeles, Department of Building and Safety has published a Homeowner's Guide (June 1974) containing "Recommendations for Maintenance of Graded Sites," which are pertinent to all graded sites: "It is incumbent upon the hillside property owner to maintain his property in a manner which will assure the continued stability of the property. The following are recommendations regarding slope and yard maintenance in graded hillside areas: l . Maintain existing slope planting, provide new approved planting where indicated, and maintain irrigation systems in working order. 2. Maintain paved diverter terraces, interceptor terraces, downdrains, appurtenances such as inlets, and velocity reducer structures in a clean condition and in good repair. 3. Earth berms prevent water from flowing over slope. It is important that these berms be maintained. 4. Standing storm water on the pad area directly above the descending slopes, whether natural, cut or fill, is a major contributor toward slope failure. It is important that the pad drainage be maintained at a minimum of 2 percent to the street or other approved location to prevent this situation. 5. Side swales which direct water around the house should be maintained so that they will not become ineffective. 6. Catch basins, grates, and subsurface drainage piping should be kept free of silt and debris. 7. Roof gutters and downspouts should be inspected periodically to assure that they are not broken or clogged. All non -erosive drainage devices should be kept clean and in good repair. 8. Extensive landscaping or revision to the property may seriously alter the surface drainage pattern. When landscaping, homeowners should avoid disrupting flow patterns created when the property was original graded. It should be remembered that normal property drainage in hillside areas is from the rear yard to the street. Some properties drain to natural water courses. 9. Any problems such as erosion should be repaired immediately in order that more serious problems may be averted. 10. Rodent activity should be controlled to prevent water penetration and loosening of the soil. 11. Care should be exercised to prevent loose fill from being placed on a grading site, especially on slopes." UTILITY TRENCH BACKFILL GUIDELINES APPENDIX P UTILITY TRENCH BACIFILL GUIDELINES The following guidelines pertinent to utility trench backfills have been adopted by the County of Orange, Environmental Management Agency Grading Section, effective March 31, 1986. The application of the guidelines is strictly enforced by the County reviewers and inspectors. 1. Each utility subcontractor (gas, electric, water, sewer, telephone, cable TV, irrigation, drainage, etc.) shall submit to the developer for dissemination to his consultants (civil engineer, geotechnical engineer, and utility contractor) a plot plan of all utility lines installed under his purview which identifies line type, material, size, depth, and approximate location. 2. The developer or his agent shall provide a composite plot plan of all utilities or a copy of all individual utility plot plans to his geotechnical engineer for use in evaluating whether all utility trench back -fills are suitable for the intended use. 3. The geotechnical engineer shall provide the County with a report which includes a plot plan showing the location of all utility trenches which: A. Are located within the load influence zone of a structure (1:1 projection) B. Are located beneath any hardscape C. Are parallel and in close proximity to the top or toe of a slope and may adversely impact slope stability if improperly backfilled D. Are located on the face of a slope in a trench 18 or more inches in depth. Typically, trenches that are less than 18 inches in depth will not be within the load influence zone if located next to a structure, and will not have a significant effect on slope stability if constructed near the top or toe of a slope and need not be shown on the plot plan unless determined to be significant by the geotechnical engineer. This plot plan may be prepared by someone other than the geotechnical engineer, but must meet his approval. 4. Backfill compaction test locations must be shown on the plot plan described in No. 3 above, and a table of test data provided in the geotechnical report. 5. The geotechnical report (utility trench backfill) must state that all utility trenches within the subject lots have been backfilled in a manner suitable for the intended use. This includes the backfill of all trenches shown on the plot plan described in No. 3 and the backfill of those trenches which did not need to be plotted on this plan.