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HomeMy WebLinkAboutPD 2021-0013; 3367 APPIAN ROAD; GEOTECHNICAL INVESTIGATION OF MINOR SLOPE FAILURE; 2020-07-23 ADVANCED GEOTECHNICAL SOLUTIONS, INC. 485 Corporate Drive, Suite B Escondido, California 92029 Telephone: (619) 867-0487 Fax: (714) 409-3287 ORANGE AND L.A. COUNTIES INLAND EMPIRE SAN DIEGO AND IMPERIAL COUNTIES (714) 786-5661 (619) 867-0487 (619) 867-0487 Bruce Blandy June 17, 2020, Revised July 23, 2020 3367 Appian Road P/W 2005-01 Carlsbad, California 92010 Report No. 2005-01-B-2R Attention: Mr. Bruce Blandy Subject: Limited Geotechnical Investigation of Minor Slope Failure, 3367 Appian Road, Carlsbad, California Advanced Geotechnical Solutions, Inc., (AGS) has prepared this report presenting the results of a limited geotechnical investigation completed at the site of a recent surficial slope failure(s) that occurred near the single family residence at 3367 Appian Road, Carlsbad, California. The surficial failure occurred on the descending slope at the rear of the residence, resulting in the partial undermining of a chain link fence located at the top of the slope and deposition of failed materials on El Camino Real. This study was conducted in order to evaluate the existing site conditions, determine potential causes of the slope failure and provide options for repair. This report has been revised to include recommendations for the construction of shotcrete and soil nails. 1.0 SCOPE OF SERVICES This study is aimed at evaluating the depth of failed soils, underlying causes, and current surficial stability of the slope. General recommendations for repair have also been included. The scope of our study included the following tasks:  Review of pertinent published and unpublished geologic and geotechnical literature, maps, and aerial photographs;  Conduct limited subsurface exploration consisting of the excavation, logging and sampling of 5 hand auger borings. The locations of the exploratory excavations are shown on Plate 1 and the logs are included in Appendix B;  Geotechnical laboratory testing on selected soil samples (Appendix C);  Preparation of a site plan showing the approximate locations of improvements and exploratory excavations (Plate 1);  Prepare geologic cross section depicting the existing site conditions and geologic contacts (Plate 1);  Compile and analyze data collected from our site reconnaissance, subsurface exploration, and laboratory testing. Specifically, our analyses included the following: o Evaluation of general subsurface conditions and description of types, distribution, and engineering characteristics of subsurface materials. June 17, 2020, Revised July 23, 2020 Page 2 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. o Perform slope stability analyses of the existing condition. o Provide recommendations on remediating the current conditions.  Preparation of this letter presenting our findings and conclusions regarding the stability of the slope. 1.1. Geotechnical Study Limitations The conclusions and recommendations in this report are professional opinions based on information provided by involved parties and the data developed during this investigation. The conclusions presented herein are based on a limited geotechnical investigation. The materials immediately adjacent to or beneath those observed may have different characteristics than those observed. No representations are made as the quality or extent of material not observed. Any evaluation regarding the presence or absence of hazardous material is beyond the scope of this firm’s services. 2.0 SITE DESCRIPTION AND OBSERVATIONS The subject single family residence is located at 3367 Appian Road in Carlsbad, California, and was constructed circa 1978. The site is identified as Lot 2 of Carlsbad Tract CT-74-5A Unit 5, Royal Homes, which was mass graded circa 1976. Based on the rough grading plan (Brian Smith Engineers, 1976), a County of San Diego Slope Easement is located on the westerly side of the lot. Rough grading for the lot appears to have occurred outside this easement and included filling to create a level pad area that drains to Appian Road. The topographic base for the grading plan shows an existing 1:1 descending slope in the easement area with a swale located atop the 1:1 slope (See Figure 1, Site Plan). An ascending 2:1 (H:V) fill slope was constructed above the swale to reach the pad grade. The pad grade generally drains towards Appian Road. An ascending fill slope was constructed to reach pad grades on the lot to the south and a descending fill slope was constructed on the lot to the north. The swale does not currently appear to be draining towards the northeast as shown on the original grading plan. The 2:1 slope drains towards the swale along with portions of the rear yard via drain lines. Outlets for these drains terminate into two gravel lined trenches that had been previously constructed near the center of the swale (personal communication with owner). It appears that one of the drains that had terminated at the northerly gravel lined trench and was redirected via a flexible pipe to bypass the swale, where the drain line then traveled down the 1:1 slope before terminating near El Camino Real. The failure buried the outlet of this flexible line. It is our understanding that surficial failures occurred during the rainfall events on or around April 10, 2020. Some of the failed materials washed onto El Camino Real. Some undermining of the fence at the top of the slope also occurred. Numerous surficial failures on cut slopes nearby the subject residence were observed during AGS’s site visit. Some of the failures were observed to be recent whereas evidence of previous failures was also observed. On a nearby paved sewer easement/footpath located southwesterly of the site, several failures covered portions of the paved footpath, with copious amounts of water percolating or being impounded by these failures. At least three separate recent surficial failures were noted on the slope below the subject residence with their approximate limits shown on Plate 1. The June 17, 2020, Revised July 23, 2020 Page 3 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. deeper failure impacted the upper portion of the slope, undermining a portion of the chain link fence, and some of this failed material washed onto El Camino Real. 3.0 FIELD INVESTIGATION Five hand augers were excavated- two within the swale and three on the 1:1 slope. Logs of the exploratory excavations are included in Appendix B, and the locations of these exploratory excavations are shown on Plate 1. Samples were also collected for laboratory testing, which included moisture density determination and both undisturbed and remolded direct shear. Laboratory test results are included in Appendix C. 4.0 STRATIGRAPHY Regional geologic maps indicate the site is underlain by Tertiary-aged Santiago Formation. Failed materials, topsoil/vegetation and compacted fill soils locally mantle the site. The following is a brief description of each geologic unit, listed from youngest to oldest. 4.1. Topsoil/Failed Materials Less than 1 foot of vegetation rich topsoil/colluvium mantles the cut slopes onsite. These materials consist of silty to clayey sands that appear to be derived from the formational materials and vegetation. Up to roughly 2 feet of failed materials were encountered on the 1:1 cut slope. The failed materials were very moist to wet and consist of clayey to silty sands derived from the fill and formational materials. Some seepage was observed in the failed materials. 4.2. Artificial Fill Compacted fill was encountered within the swale on top of the slope. It is not known when this fill was placed. It may have been placed in 1976 when the tract was rough graded or may have been placed prior since the topography of the swale area predates the rough grading plan. The fill consists of tan clayey sand that was observed to be dense and moist. The fill is likely locally derived as it is similar in composition to the underlying formational materials. 4.3. Tertiary-aged Santiago Formation (Map Symbol Tsa) Tertiary-aged Santiago Formation materials underlie the site at depth. As observed, the Santiago Formation generally consists of interbedded light yellow brown to light tan clayey sandstone, silty sandstone, and conglomerate, with occasional claystone beds. The upper formational materials near the top of the cut slope were observed to be weathered with root lined fractures/cracks. The formational materials were observed to be moist to very moist and dense below about 1 to 2 feet. The bedding inclination and dip could not be readily determined in the borings. 5.0 GEOTECHNICAL ENGINEERING Presented herein is a general discussion of the geotechnical properties of the various soil types and the analytic methods used in this report. June 17, 2020, Revised July 23, 2020 Page 4 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. 5.1. Shear Strength Based on our laboratory test results and previous experience in the area with similar soils, the following shear strengths for the upper surficial soils (Topsoil/failed materials) and engineered fill/ weathered formational materials are presented on Table 5.1. The shear strength of the upper soil materials was estimated using the direct shear test results of a sample remolded from the failed materials at a lower density (114 pcf). TABLE 5.1 RECOMMENDED SHEAR STRENGTHS FOR DESIGN Material Cohesion (psf) Friction Angle (degrees) Total Unit Weight (pcf) Topsoil/Failed Materials 100 32 120 Compacted Fill/Weathered Formation. 500 29 125 5.2. Slope Stability Slope stability analyses were performed on a representative cross-section to evaluate global stability. Existing conditions were evaluated. Limit equilibrium slope stability analyses were compiled using Rocscience Slide2. To search for critical failure surfaces, a path type search was generally utilized coupled with optimization techniques. The path type search randomly generates a discrete number of potential non-circular surfaces (generally 5,000 to 50,000 potential failure surfaces) to find the failure surface with the lowest factor of safety. The factor of safety was calculated using Spencer’s methods. The results of the global stability analyses are presented in Appendix C. Based on the results of the analysis, the existing slope has a factor of safety of greater than 1.5 for static conditions. However, the analysis assumed that no weak out-of-slope bedding conditions are present. However, the cut slopes are not considered surficially stable based on the presence of several surficial failures and slumps. 6.0 CONCLUSIONS The observed failures appear to shallow, impacting the upper surficial soils. Evidence of a deep seated landslide was not observed. The existing slope is mantled by weathered formational materials that are not considered stable for the steep conditions when saturated. The formational materials consist of interbedded silty and clayey sandstone with claystone. Infiltrating water likely percolates through some of the more permeable silty sand layers and becomes perched atop less permeable layers. When saturated, the apparent cohesion of the upper soils is reduced, and the upper soils are prone to failure at their current inclinations. The current grasses and ice plant vegetation on the slope have shallow root zones and add weight to the slope face. Whereas this type of vegetation cover may mitigate the potential for erosion, it may also contribute to the potential for surficial failures. June 17, 2020, Revised July 23, 2020 Page 5 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. It is believed that infiltrating water ponded on some of the less permeable layers, allowing layers within the formation to become saturated. These formational materials failed during the heavy rainfall event on April 10, 2020, and the failure propagated upwards. One of these failures undermined a section of chain link fence and impacted some of the fill materials at the top of the slope. Drainage is critical to maintain stability of the cut slope. The surficial stability of the existing 1:1 slope is marginal when saturated. 7.0 GRADING RECOMMENDATIONS Whereas the existing slope is expected to be globally stable, it is prone to surficial sliding when the upper soils are saturated. Varying levels of mitigation can be done to decrease the potential for future surficial sliding. Generally, there is a relationship between the cost of a repair versus the reduction of risk. AGS has provided various options below after discussing with the owner their expectations, concerns, and budget constraints. Options such as covering the slope with shotcrete and anchors or laying back the slope combined with constructing pile supported walls, may substantially reduce the risk of future surficial failures but may be financially infeasible. The following options are provided to reduce the potential, but not prevent future surficial failures. Additional maintenance may be required and future failures should be removed and repaired when they occur.  Drainage should be provided so that no runoff, including roof and area drains, is directed on the slope. This may require installing a ditch or area drain in the existing swale area. The existing swale may need to be improved on the northerly adjacent neighbor’s property if flow is re- established to continue to the north. Alternatively, a drain may need to be installed down the existing slope to outlet into El Camino Real. These options should be evaluated by a civil engineer to determine the best course of action. If a drain is installed on the slope, special considerations for installation and backfill on steep slopes is provided in Section 7.7.  The failed materials consist of a mix of vegetation and soil and may be sitting atop topsoil and vegetation. These materials are considered susceptible to future erosion and/or failures and should be stripped from the slope face.  The upper failure scarp area should be restored. Different options are provided: 1. The slope can be laid back to a 2:1 inclination around the scarp. However, this will encroach on the swale and the current fence will need to be moved or rebuilt in the area. 2. Alternatively, the slope at the scape area can be re-constructed using reinforcement. The slope can be replaced with a reinforced soil slope (RSS). Inclinations of up to 0.5(H):1(V) can be achieved with a RSS. The slope would be restored by constructing a keyway at the bottom of the scarp. Reinforcement should be added consisting of primary and secondary geogrid layers. Reinforced soil slopes are typically more difficult to construct than unreinforced slopes and much more expensive. The reinforced soil slopes should be constructed by an experienced contractor. Repair recommendations are provided herein for constructing a 1(H):1(V) RSS. 3. Another option for reconstructing a slope may include the use of a pile and board system. Pipe piles are driven into the slope or anchored in concrete to support boards, which are tied June 17, 2020, Revised July 23, 2020 Page 6 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. to the piles. Backfill is then placed and compacted behind the boards. Such as system is likely cheaper to construct initially, but will typically require additional maintenance. The system may also need to be replaced in the future. The pile should be sufficiently embedded below the creep impacted soils and several feet into the formational deposits. It can be driven or embedded in a concrete caisson. Freeboard should be provided at each step to collect failed materials. The steps should be regularly cleaned of the failed materials. 4. The slope failure areas can be mitigated by construction of a shotcrete facing with soil nails. The anchor will be connected to the shotcrete wall. The existing walls will essentially be used as formwork for the shotcrete and anchor wall system. Due to the limited access, constructing the shotcrete facing and drilling will be completed with small equipment and is expected to take a considerable amount of time to complete.  Vegetation should be installed on the cut slope to enhance the stability. Deep rooted plants should be used. The existing vegetation with shallow roots should be replaced. This option may also require temporary irrigation until the plants are established. Alternatively, an anchored erosion control mat can be installed on the slope. The anchors would need to be embedded into the formational materials. Grouted anchors or helical type anchors are typically used. The use of measures such as a jute mesh may help mitigate erosion of the slope but will not enhance the surficial stability. Alternatively, pipe and boards may be installed on the slope to enhance the stability and allow for the collection of some of the failed materials.  Combinations of these measures can also be considered.  Alternative recommendations can be provided such as construction of a soldier pile and lagging wall at the top of the slope. However, this option is more expensive than the previously described options. 7.1. Earthwork Recommendations and Considerations All grading shall be accomplished under the observation and testing of the project Geotechnical Consultant in accordance with the recommendations contained herein, the current codes practiced by the City of Carlsbad and this firm’s Earthwork Specifications (Appendix D). Existing vegetation, trash, debris, and other deleterious materials should be removed and wasted from the site prior to commencing removal of unsuitable soils and placement of compacted fill materials. The existing failed materials on the slope should be removed. In general, the removed materials are suitable to be reused as compacted fill provided deleterious materials such as vegetation are removed. 7.2. Remediation Option Recommendations The following sections provide preliminary recommendations for Options 1 and 2, as discussed in Section 7.0 above, to remediate the existing condition. June 17, 2020, Revised July 23, 2020 Page 7 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. 7.2.1. OPTION 1- Restore Scarp with Reinforced Soil Slope A stabilization keyway should be constructed below the failed area. The limits of this keyway should be based on the final slope design, but should be no less than 6 feet wide. Reinforced soil slopes (RSS) should be constructed on fill slopes steeper than 2:1. The grading contractor should have experience in the construction of a RSS. There are several methods on constructing a RSS, such as using temporary wooden formwork or permanent wire mesh forms (See Figure 7.2.1, below). The construction method should allow for the fill to be compacted out to the slope face without damaging the reinforcement. Figure 7.2.1 Alternative Methods of RSS Construction (from TenCate™) The primary reinforcement can include placing layers of Mirafi Miragrid 2XT (or approved equivalent) every 2 feet vertically starting from the bottom of the keyway. The primary geogrid layers should extend from the slope face to the backcut. The primary geogrid should be oriented so that the primary strength is perpendicular to the slope face. Splices in the primary direction should be avoided. A secondary layer of reinforcement consisting of Mirafi Miramesh TR (or approved equivalent) should be wrapped around the slope face and embedded a minimum of 4 feet with a maximum vertical spacing of 1 foot. The Miramesh vertical spacing can be reduced to every 2 feet if the primary geogrid layer is wrapped on the outside of the Miramesh and the primary geogrid is June 17, 2020, Revised July 23, 2020 Page 8 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. embedded a minimum of 6 feet as measured from the slope face. Splicing of the secondary layer shall not be conducted. 7.2.2. OPTION 2- Pipe and Board System The slope can be restored using a pipe and board system. Failed materials should be removed to expose competent materials and benches should be constructed on the exposed slope. The pipes should be sufficiently embedded at least 5 feet into the underlying formational materials and should be of sufficient size to support the lateral loading conditions. The pipes can be driven or embedded in concrete. The slope can be restored by compacting materials behind and in front of the lagging boards. Materials should be compacted per Section 7.5. 7.2.3. OPTION 3- Shotcrete with Soil Nails The shotcrete with soil nail system should be designed by a licensed engineer familiar with these systems. The soil nail capacity is dependent on the drilling and grouting methods and should be estimated by the specialty contractor. Testing should be conducted during construction. For preliminary estimating purposes, ultimate anchor capacities in the sandstone/siltstone can be assumed to be 4,300 pounds per square foot (30 psi). Since the above friction capacities are considered ultimate, an appropriate factor of safety should be incorporated into the design. Soils nails should be embedded a minimum of 10 feet. 7.2.4. Temporary Backcut Stability During grading operations, temporary backcuts will be required to accomplish removals and provide room to place geogrid. Care should be taken during backcut construction and backfill should be placed expeditiously in order to minimize risk of failure. Complete removal of the failed materials will be required should failure occur. Backcuts exposing competent formational materials/bedrock should be made no steeper than 1:1 to heights of up to 15 feet. Steeper backcuts may be possible for smaller sections but should be evaluated by AGS. Close geologic mapping of the stabilization and buttress key backcuts should be provided to document the exposed conditions. Revised recommendations may be necessary should areas of instability be encountered. In consideration of the inherent instability created by temporary construction of backcuts, it is imperative that grading schedules be coordinated to minimize the unsupported exposure time of these excavations. Once started these excavations and subsequent fill operations should be maintained to completion without intervening delays imposed by avoidable circumstances. In cases where five-day workweeks comprise a normal schedule, grading should be planned to avoid exposing at-grade or near-grade excavations through a non-work weekend. Where improvements may be affected by temporary instability, either on or offsite, further restrictions such as slot cutting, extending work days, implementing weekend schedules, and/or other requirements considered critical to serving specific circumstances may be imposed. June 17, 2020, Revised July 23, 2020 Page 9 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. 7.3. Geologic Observation During Grading All temporary slope excavations, including front, side and backcuts, and all cut slopes should be mapped to verify the geologic conditions that were modeled prior to grading. 7.4. Seepage Seepage, if encountered during grading, should be evaluated by the Geotechnical Consultant. If seepage is excessive, remedial measures such as horizontal drains or under drains may need to be installed. 7.5. Earthwork Considerations 7.5.1. Compaction Standards All fills should be compacted to at least 90 percent of the maximum dry density as determined by ASTM D1557. All loose and or deleterious soils should be removed to expose firm native soils or bedrock. Prior to the placement of fill, the upper 6 to 8 inches of suitable material should be ripped, moisture conditioned to optimum moisture or slightly above optimum, and compacted to a minimum of 90 percent of the maximum dry density (ASTM D1557). Fill should be placed in thin (6 to 8-inch) lifts, moisture conditioned to optimum moisture or slightly above, and compacted to at least 90 percent of the maximum dry density (ASTM D1557) until the desired grade is achieved. 7.5.2. Benching Where the natural slope is steeper than 5-horizontal to 1-vertical and where determined by the Geotechnical Consultant, compacted fill material shall be keyed and benched into competent materials. 7.5.3. Mixing and Moisture Control In order to prevent layering of different soil types and/or different moisture contents, mixing and moisture control of materials will be necessary. The preparation of the earth materials through mixing and moisture control should be accomplished prior to and as part of the compaction of each fill lift. Water trucks or other water delivery means may be necessary for moisture control. Discing may be required when either excessively dry or wet materials are encountered. 7.5.4. Haul Roads All haul roads, ramp fills, and tailing areas shall be removed prior to engineered fill placement. 7.5.5. Import Soils Import soils, if required, should consist of clean, structural quality, compactable materials similar to the on-site soils and should be free of trash, debris or other objectionable materials. Import soils should be tested and approved by the Geotechnical Consultant June 17, 2020, Revised July 23, 2020 Page 10 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. prior to importing. At least three working days should be allowed in order for the geotechnical consultant to sample and test the potential import material. 7.5.6. Fill Slope Construction Fill slopes may be constructed by preferably overbuilding and cutting back to the compacted core or by back-rolling and compacting the slope face. The following recommendations should be incorporated into construction of the proposed fill slopes. Care should be taken to avoid spillage of loose materials down the face of any slopes during grading. Spill fill will require complete removal before compaction, shaping and grid rolling. Seeding and planting of the slopes should follow as soon as practical to inhibit erosion and deterioration of the slope surfaces. Proper moisture control will enhance the long- term stability of the finish slope surface. 7.5.6.1. Overbuilding Fill Slopes Fill slopes should be overfilled to an extent determined by the contractor, but not less than 2 feet measured perpendicular to the slope face, so that when trimmed back to the compacted core, the compaction of the slope face meets the minimum project requirements for compaction. Compaction of each lift should extend out to the temporary slope face. The sloped should be back-rolled at fill intervals not exceeding 4 feet in height unless a more extensive overfilling is undertaken. 7.5.6.2. Compacting the Slope Face As an alternative to overbuilding the fill slopes, the slope faces may be back- rolled with a heavy-duty loaded sheepsfoot or vibratory roller at maximum 2-foot fill height intervals. Back-rolling at more frequent intervals may be required. Compaction of each fill should extend to the face of the slope. 7.5.6.3. Reinforced Soil Slopes Reinforced soil slopes should be constructed by an experienced contractor. Compaction of the slope face is often achieved through the use of temporary or permanent forms. 7.6. Civil Design Recommendations Final site grading should assure positive drainage away from structures and slopes. A concrete swale should be constructed at the top of the slope to capture offsite irrigation and rainfall runoff. Planter areas should be provided with area drains to transmit irrigation and rain water away from structures and slopes. The use of gutters and down spouts to carry roof drainage well away from structures is recommended. Raised planters should be provided with a positive means to remove water through the face of the containment wall. June 17, 2020, Revised July 23, 2020 Page 11 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. 7.7. Special Considerations for Pipe Installation on Steep Slopes The installations of pipes on steep slopes require additional measures. If installed on the slope, drain pipes should be anchored to the slope. One method includes supporting an exposed pipe on piers. If installing a buried pipe, one method would be to install concrete pipe slope anchors at a maximum spacing of 12 feet along the pipe profile. The anchor can consist of a 12-inch wide rectangular reinforced concrete block that extends a minimum of 12 inches outside the pipe. Reinforcement can consist of #4 bars placed on the 4 sides. The bottom of the pipe anchor should extend at least 12 inches into competent formational materials, or three feet below the slope surface, whichever is deeper. Other anchorage systems can be used if the alternate system is approved by the civil engineer or building official. Bedding and backfill materials should not consist of materials with little or no cohesion and are prone to erosion. Alternative soils may include soils with some cohesion such as clayey sands that are compacted to a minimum of 95 percent relative compaction. Controlled low strength material (CLSM) can be also be used and capped with native soils that are mechanically compacted. 8.0 SLOPE AND LOT MAINTENANCE Maintenance of improvements is essential to the long-term performance of structures and slopes. Although the design and construction during mass grading created slopes that are considered both grossly and surficially stable, certain factors are beyond the control of the soil engineer and geologist. The homeowners must implement certain maintenance procedures. The following recommendations should be implemented. 8.1. Slope Planting Slope planting should consist of ground cover, shrubs and trees that possess deep, dense root structures and require a minimum of irrigation. The resident should be advised of their responsibility to maintain such planting. 8.2. Lot Drainage Roof, pad and lot drainage should be collected and directed away from structures and slopes and toward approved disposal areas. Design fine-grade elevations should be maintained through the life of the structure, or if design fine grade elevations are altered, adequate area drains should be installed in order to provide rapid discharge of water away from structures and slopes. Residents should be made aware that they are responsible for maintenance and cleaning of all drainage terraces, downdrains, and other devices that have been installed to promote structure and slope stability. 8.3. Slope Irrigation The resident, homeowner and Homeowner Association should be advised of their responsibility to maintain irrigation systems. Leaks should be repaired immediately. Sprinklers should be adjusted to provide maximum uniform coverage with a minimum of water usage and overlap. Overwatering with consequent wasteful run-off and ground saturation should be avoided. If June 17, 2020, Revised July 23, 2020 Page 12 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. automatic sprinkler systems are installed, their use must be adjusted to account for natural rainfall conditions. 8.4. Burrowing Animals Residents or homeowners should undertake a program for the elimination of burrowing animals. This should be an ongoing program in order to maintain slope stability. 9.0 LIMITATIONS This report is based on the project as described and the information obtained from the excavations at the approximate locations indicated on Plate 1. The findings are based on the results of the field and office investigations combined with an interpolation and extrapolation of conditions between and beyond the excavation locations. The results reflect an interpretation of the direct evidence obtained. Services performed by AGS have been conducted in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions. No other representation, either expressed or implied, and no warranty or guarantee is included or intended. The recommendations presented in this report are based on the assumption that an appropriate level of field review will be provided by geotechnical engineers and engineering geologists who are familiar with the design and site geologic conditions. That field review shall be sufficient to confirm that geotechnical and geologic conditions exposed during grading are consistent with the geologic representations and corresponding recommendations presented in this report. AGS should be notified of any pertinent changes in the project plans or if subsurface conditions are found to vary from those described herein. Such changes or variations may require a re-evaluation of the recommendations contained in this report. The data, opinions, and recommendations of this report are applicable to the specific design of this project as discussed in this report. They have no applicability to any other project or to any other location, and any and all subsequent users accept any and all liability resulting from any use or reuse of the data, opinions, and recommendations without the prior written consent of AGS. AGS has no responsibility for construction means, methods, techniques, sequences, or procedures, or for safety precautions or programs in connection with the construction, for the acts or omissions of the CONTRACTOR, or any other person performing any of the construction, or for the failure of any of them to carry out the construction in accordance with the final design drawings and specifications. June 17, 2020, Revised July 23, 2020 Page 13 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact the undersigned. ___________________________________ __________________________________ JOHN J. DONOVAN PAUL J. DERISI RCE 65051, RGE 2790, Reg. Exp. 6-30-21 CEG 2536, Reg. Exp. 5-31-21 2005-01-B-2R (Jun 17, 2020, Revised Jul 23, 2020, Slope Failure, 3367 Appian Rd, Carlsbad).docx Distribution: (1) Addressee (pdf) Appended: Plate 1- Site Plan and Geologic Cross-Section Appendix A- References Appendix B- Exploratory Logs Appendix C- Laboratory Test Results Appendix D- Slope Stability Analysis Appendix E- General Earthwork Specifications ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX A REFERENCES June 17, 2020, Revised July 23, 2020 Page A-1 P/W 2005-01 Report No. 2005-01-B-2R ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX A REFERENCES Brian Smith Engineers, Inc. (1976). “Grading Plan for: Royal Homes Unit 5, Carlsbad Tract No. 74-5A,” Sheet 2 of 2, Drawing No. 187-6A, As Built Drawing dated August 13, 1976. Kennedy, M.P., Tan, S.S., Bovard, K.R., Alvarez, R.M., Watson, M.J., and Gutierrez, C.I., 2007, Geologic map of the Oceanside 30x60-minute quadrangle, California: California Geological Survey, Regional Geologic Map No. 2, scale 1:100,000. ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX B EXPLORATORY LOGS June 17, 2020 Page A-1 P/W 2005-01 Report No. 2005-01-B-2 ADVANCED GEOTECHNICAL SOLUTIONS, INC. Dated Excavated: May 14, 2020 Logged By: SD (HA-1, 3, 4); VM (HA-2) LOG OF HAND AUGERS AND UPPER FAILURE SCARP HA-1 (Top of Slope, 5ft from Top of Slope/Fence) Depth (feet) Description 0 - 0.25 TOPSOIL: SILTY SAND, fine-grained, dark brown, with roots, slightly moist. 0.25 - 4 ARTIFICIAL FILL: CLAYEY SAND, fine to coarse-grained, mottled, brown, light orange brown, moist, medium dense. @ 1.5 ft. - medium dense to dense, some pieces of asphalt concrete Ring Sample at 1.5 ft: Moisture=9.7%, Dry Density = 109 pcf @ 3 ft. - dense, moist, tan, slightly mottled, some pieces of asphalt concrete Ring Sample at 3.5 ft: Moisture=9.4%, Dry Density = 125 pcf 4 - 9.5 SANTIAGO FORMATION (Tsa): CLAYEY SANDSTONE, tan, slightly mottled, very moist, soft. @ 6 ft. - SILTY SANDSTONE, fine to coarse-grained, very moist @ 6.5 ft. - more difficult to auger, CLAYEY SANDSTONE @ 7 ft. - decrease in clay content @ 8 ft. - increase in clay content @ 8.5 ft. - fine grained, more clay @9 ft - decrease in clay content Total Depth 9.5 feet. No water. HA-2 (Top of Slope, 5ft from Top of Slope/Fence) Depth (feet) Description 0 - 0.25 TOPSOIL: SILTY SAND, fine-grained, dark brown, with roots, slightly moist. 0.25 - 3.5 ARTIFICIAL FILL: CLAYEY SAND, fine to coarse-grained, mottled, brown, light orange brown, moist, medium dense, pieces of asphalt concrete. 3.5 - 9.5 SANTIAGO FORMATION (Tsa): CLAYEY SANDSTONE, tan, slightly mottled, moist to very moist, soft. @ 7 ft. - fine grained SAND @ 7.5 ft. - dark brown CLAY layer Total Depth 9.5 feet. No water. June 17, 2020 Page A-2 P/W 2005-01 Report No. 2005-01-B-2 ADVANCED GEOTECHNICAL SOLUTIONS, INC. HA-3 (Slope, 3.5’H and 7’V from Top) Depth (feet) Description 0 - 1.5 DISTURBED/FAILED MATERIALS: CLAYEY SAND, fine to medium grained, soft, very moist. 1.5 - 4 SANTIAGO FORMATION (Tsa): CLAYEY SANDSTONE, tan, slightly mottled, moist to very moist, soft. @ 3 ft. - SILTY SANDSTONE @ 4 ft. - mottled, orange brown, tan @ 5.5 ft. - CLAYEY SANDSTONE Total Depth 6 feet. No water. Bulk Samples 0.5 feet and 3-3.5 feet HA-4 (Mid-Slope, 12.5’H and -6.5’V from HA-3) Depth (feet) Description 0 - 3 DISTURBED/FAILED MATERIALS: Mix of CLAYEY SAND and vegetation (grass). @ 0.5 ft. - less but abundant vegetation, dark brown and orange brown, moist @ 1 ft. - very moist @ 2 ft. - wet, slight seepage in sides of hole. @ 3 ft. - lightly harder to auger (Contact with Formation?) 3 - 4 SANTIAGO FORMATION (Tsa): CLAYEY SANDSTONE, less clay than soils above, very moist, some rounded gravel, tan. @ 4 ft. - CONGLOMERATE, rounded cobble in clayey sand matrix Refusal at 4 feet on cobble layer. Slight seepage at 2 feet. June 17, 2020 Page A-3 P/W 2005-01 Report No. 2005-01-B-2 ADVANCED GEOTECHNICAL SOLUTIONS, INC. HA-5 (Mid-Slope, 9.5’H and +4’V from edge of sidewalk Depth (feet) Description 0 - 1.5 TOPSOIL/COLLUVIUM: CLAYEY SAND, with rounded gravel, occasional cobbles, some roots, orange brown, moist. @ 1 ft. - lighter in color, light yellow brown @ 1.5 ft. - more difficult to excavate, piece of SILTSTONE (Contact with Formation?) 1.5 - 2.5 SANTIAGO FORMATION (Tsa): SANDY SILTSTONE, tan, moist. @ 2 ft. - difficult to excavate Total Depth 2.5 feet. No Water. Failure Scarp at Top of Slope (6 foot vertical) Depth (feet) Description 0 - 3 ARTIFICIAL FILL: CLAYEY SAND, fine to coarse-grained, slightly moist at outer surface of scarp, moist at a depth of a few inches, FILL/FORMATION contact slightly dipping into slope. 3 - 6 SANTIAGO FORMATION (Tsa): CLAYEY SANDSTONE, weathered, carbonate lined fractures to 5 feet, filled gopher hole at 4.5 feet on left wall. ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX C LABORATORY TEST RESULTS June 17, 2020 Page B-1 P/W 2005-01 Report No. 2005-01-B-2 ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX C LABORATORY TEST RESULTS The results of laboratory testing performed during this study are enclosed within this Appendix. Descriptions of the testing procedures are presented below. Classification Soils were classified with respect to the Unified Soil Classification System (USCS) in accordance with ASTM D2487 and D2488. Direct Shear Tests Direct shear tests were performed on relatively undisturbed samples and samples that were remolded. Samples were saturated in a confined condition prior to testing. The apparatus used is in conformance with the requirements outlined in ASTM Test Method: D3080. The test specimens (1-inch in height and 2.42-inches in diameter) were subjected to simple shear along a plane at mid-height. The samples were sheared under various normal loads, a different specimen being used for each normal load. The specimens were sheared until the sample deformation had reached approximately 0.25 inches. The shear stress values obtained from the tests were plotted versus the applied normal pressures. An appropriate straight line was drawn through the plotted points to obtain the shear strength envelope. The direct shear test results are appended. Project Name: 3367 Appian Rd Excavation: HA-3 Location: Carlsbad Depth: 0.5 ft Project No.: 2005-01 Tested by: FV Date: Reviewed by: Samples Tested 123 Soil Type: Light Brn. SC-SM Intial Moisture (%) 9.4 9.4 9.4 Test: Remlded 90% Initial Dry Density (pcf) 114.0 114.0 114.0 Method: Drained Normal Stress (psf) 1000 2000 4000 Consolidation: Yes Peak Shear Stress (psf) 804 1464 2640 Saturation: Yes Ult. Shear Stress (psf) 756 1440 2628 Shear Rate (in/min):0.01 Strength Parameters Peak Ultimate Friction Angle, phi (deg)32 32 Cohesion (psf)150 150 ADVANCED GEOTECHNICAL SOLUTIONS, INC. DIRECT SHEAR - ASTM D3080 6/3/2020 ‐0.02 ‐0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.00 0.10 0.20 0.30Vertical Deformation (in)Displacement (in) Vertical Deformation v. Displacement 4000 2000 10000 500 1000 1500 2000 2500 3000 0.00 0.10 0.20 0.30Shear Stress (psf)Displacement (in) Shear Stress v. Displacement 4000 2000 1000 0 500 1000 1500 2000 2500 3000 0 500 1000 1500 2000 2500 3000 3500 4000 4500Shear Stress (psf)Normal Stress (psf) Peak Peak Ultimate Ultimate Project Name: 3367 Appian Rd Excavation: HA-1 Location: Carlsbad Depth: 3.5 ft Project No.: 2005-01 Tested by: FV Date: Reviewed by: SD Samples Tested 123 Soil Type: Coarse Light Brn SM Intial Moisture (%) 9.4 9.4 9.4 Test: Undisturbed Initial Dry Density (pcf) 123.3 127.9 123.2 Method: Drained Normal Stress (psf) 1000 2000 4000 Consolidation: Yes Peak Shear Stress (psf) 1512 2532 3456 Saturation: Yes Ult. Shear Stress (psf) 1416 1788 3036 Shear Rate (in/min):0.01 Strength Parameters Peak Ultimate Friction Angle, phi (deg)34 29 Cohesion (psf)850 790 ADVANCED GEOTECHNICAL SOLUTIONS, INC. DIRECT SHEAR - ASTM D3080 5/20/2020 ‐0.02 ‐0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.00 0.10 0.20 0.30Vertical Deformation (in)Displacement (in) Vertical Deformation v. Displacement 4000 2000 10000 500 1000 1500 2000 2500 3000 3500 4000 0.00 0.10 0.20 0.30Shear Stress (psf)Displacement (in) Shear Stress v. Displacement 4000 2000 1000 y = 25.432x0.5963 0 500 1000 1500 2000 2500 3000 3500 4000 0 500 1000 1500 2000 2500 3000 3500 4000 4500Shear Stress (psf)Normal Stress (psf) Peak Peak Ultimate Ultimate Power (Peak) ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX C SLOPE STABILITY ANALYSIS 1.9461.9461.9461.946Material NameColorUnit Weight(lbs/Ō3)Strength TypeCohesion(psf)Phi(deg)WaterSurfaceRuFill125Mohr‐Coulomb50029None0SanƟago FormaƟon125Mohr‐Coulomb50029None0Topsoil‐Failed Materials120Mohr‐Coulomb10032None0Safety Factor1.0001.0421.0831.1251.1671.2081.2501.2921.3331.3751.4171.4581.5001.5421.5831.6251.6671.7081.7501.7921.8331.8751.9171.9582.000+280260240220200-20020406080100120Analysis DescriptionSection A-A', Global Deep Failure (Cross-Bedding)CompanyAGSScale1:178Drawn BySDFile Name2005-01 section a-a.slimDate6-11-2020Project3367 Appian RoadSLIDEINTERPRET 8.032 ADVANCED GEOTECHNICAL SOLUTIONS, INC. APPENDIX D GENERAL EARTHWORK SPECIFICATIONS General Earthwork Specifications Page 1 ADVANCED GEOTECHNICAL SOLUTIONS, INC. GENERAL EARTHWORK SPECIFICATIONS I. General A. General procedures and requirements for earthwork and grading are presented herein. The earthwork and grading recommendations provided in the geotechnical report are considered part of these specifications, and where the general specifications provided herein conflict with those provided in the geotechnical report, the recommendations in the geotechnical report shall govern. Recommendations provided herein and in the geotechnical report may need to be modified depending on the conditions encountered during grading. B. The contractor is responsible for the satisfactory completion of all earthwork in accordance with the project plans, specifications, applicable building codes, and local governing agency requirements. Where these requirements conflict, the stricter requirements shall govern. C. It is the contractor’s responsibility to read and understand the guidelines presented herein and in the geotechnical report as well as the project plans and specifications. Information presented in the geotechnical report is subject to verification during grading. The information presented on the exploration logs depict conditions at the particular time of excavation and at the location of the excavation. Subsurface conditions present at other locations may differ, and the passage of time may result in different subsurface conditions being encountered at the locations of the exploratory excavations. The contractor shall perform an independent investigation and evaluate the nature of the surface and subsurface conditions to be encountered and the procedures and equipment to be used in performing his work. D. The contractor shall have the responsibility to provide adequate equipment and procedures to accomplish the earthwork in accordance with applicable requirements. When the quality of work is less than that required, the Geotechnical Consultant may reject the work and may recommend that the operations be suspended until the conditions are corrected. E. Prior to the start of grading, a qualified Geotechnical Consultant should be employed to observe grading procedures and provide testing of the fills for conformance with the project specifications, approved grading plan, and guidelines presented herein. All clearing and grubbing, remedial removals, clean-outs, removal bottoms, keyways, and subdrain installations should be observed and documented by the Geotechnical Consultant prior to placing fill. It is the contractor’s responsibility to apprise the Geotechnical Consultant of their schedules and notify the Geotechnical Consultant when those areas are ready for observation. F. The contractor is responsible for providing a safe environment for the Geotechnical Consultant to observe grading and conduct tests. II. Site Preparation A. Clearing and Grubbing: Excessive vegetation and other deleterious material shall be sufficiently removed as required by the Geotechnical Consultant, and such materials shall be General Earthwork Specifications Page 2 ADVANCED GEOTECHNICAL SOLUTIONS, INC. properly disposed of offsite in a method acceptable to the owner and governing agencies. Where applicable, the contractor may obtain permission from the Geotechnical Consultant, owner, and governing agencies to dispose of vegetation and other deleterious materials in designated areas onsite. B. Unsuitable Soils Removals: Earth materials that are deemed unsuitable for the support of fill shall be removed as necessary to the satisfaction of the Geotechnical Consultant. C. Any underground structures such as cesspoles, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, other utilities, or other structures located within the limits of grading shall be removed and/or abandoned in accordance with the requirements of the governing agency and to the satisfaction of the Geotechnical Consultant. Environmental evaluation of existing conditions is not the responsibility of the Geotechnical Consultant. D. Preparation of Areas to Receive Fill: After removals are completed, the exposed surfaces shall be processed or scarified to a depth of approximately 8 inches, watered or dried, as needed, to achieve a generally uniform moisture content that is at or near optimum moisture content. The scarified materials shall then be compacted to the project requirements and tested as specified. E. All areas receiving fill shall be observed and approved by the Geotechnical Consultant prior to the placement of fill. A licensed surveyor shall provide survey control for determining elevations of processed areas and keyways. III. Placement of Fill A. Suitability of fill materials: Any materials, derived onsite or imported, may be utilized as fill provided that the materials have been determined to be suitable by the Geotechnical Consultant. Such materials shall be essentially free of organic matter and other deleterious materials, and be of a gradation, expansion potential, and/or strength that is acceptable to the Geotechnical Consultant. Fill materials shall be tested in a laboratory approved by the Geotechnical Consultant, and import materials shall be tested and approved prior to being imported. B. Generally, different fill materials shall be thoroughly mixed to provide a relatively uniform blend of materials and prevent abrupt changes in material type. Fill materials derived from benching should be dispersed throughout the fill area instead of placing the materials within only an equipment-width from the cut/fill contact. C. Oversize Materials: Rocks greater than 12 inches in largest dimension shall be disposed of offsite or be placed in accordance with the recommendations by the Geotechnical Consultant in the areas that are designated as suitable for oversize rock placement. Rocks that are smaller than 8 inches in largest dimension may be utilized in the fill provided that they are not nested and are their quantity and distribution are acceptable to the Geotechnical Consultant and do not inhibit the ability to properly compact fill materials. General Earthwork Specifications Page 3 ADVANCED GEOTECHNICAL SOLUTIONS, INC. D. The fill materials shall be placed in thin, horizontal layers such that, when compacted, shall not exceed 6 inches. Each layer shall be spread evenly and shall be thoroughly mixed to obtain a near uniform moisture content and uniform blend of materials. E. Moisture Content: Fill materials shall be placed at or above the optimum moisture content or as recommended by the geotechnical report. Where the moisture content of the engineered fill is less than recommended, water shall be added, and the fill materials shall be blended so that a near uniform moisture content is achieved. If the moisture content is above the limits specified by the Geotechnical Consultant, the fill materials shall be aerated by discing, blading, or other methods until the moisture content is acceptable. F. Each layer of fill shall be compacted to the project standards in accordance to the project specifications and recommendations of the Geotechnical Consultant. Unless otherwise specified by the Geotechnical Consultant, the fill shall be compacted to a minimum of 90 percent of the maximum dry density as determined by ASTM Test Method: D1557. G. Benching: Where placing fill on a slope exceeding a ratio of 5 to 1 (horizontal to vertical), the ground should be keyed or benched. The keyways and benches shall extend through all unsuitable materials into suitable materials such as firm materials or sound bedrock or as recommended by the Geotechnical Consultant. The minimum keyway width shall be 15 feet and extend into suitable materials, or as recommended by the geotechnical report and approved by the Geotechnical Consultant. The minimum keyway width for fill over cut slopes is also 15 feet, or as recommended by the geotechnical report and approved by the Geotechnical Consultant. As a general rule, unless otherwise recommended by the Geotechnical Consultant, the minimum width of the keyway shall be equal to ½ the height of the fill slope. H. Slope Face: The specified minimum relative compaction shall be maintained out to the finish face of fill and stabilization fill slopes. Generally, this may be achieved by overbuilding the slope and cutting back to the compacted core. The actual amount of overbuilding may vary as field conditions dictate. Alternately, this may be achieved by backrolling the slope face with suitable equipment or other methods that produce the designated result. Loose soil should not be allowed to build up on the slope face. If present, loose soils shall be trimmed to expose the compacted slope face. I. Slope Ratio: Unless otherwise approved by the Geotechnical Consultant and governing agencies, permanent fill slopes shall be designed and constructed no steeper than 2 to 1 (horizontal to vertical). J. Natural Ground and Cut Areas: Design grades that are in natural ground or in cuts should be evaluated by the Geotechnical Consultant to determine whether scarification and processing of the ground and/or overexcavation is needed. K. Fill materials shall not be placed, spread, or compacted during unfavorable weather conditions. When grading is interrupted by rain, filing operations shall not resume until the Geotechnical Consultant approves the moisture and density of the previously placed compacted fill. General Earthwork Specifications Page 4 ADVANCED GEOTECHNICAL SOLUTIONS, INC. IV. Cut Slopes A. The Geotechnical Consultant shall observe all cut slopes, including fill over cut slopes, and shall be notified by the contractor when cut slopes are started. B. If adverse or potentially adverse conditions are encountered during grading, the Geotechnical Consultant shall investigate, evaluate, and make recommendations to mitigate the adverse conditions. C. Unless otherwise stated in the geotechnical report, cut slopes shall not be excavated higher or steeper than the requirements of the local governing agencies. Short-term stability of the cut slopes and other excavations is the contractor's responsibility. V. Drainage A. Backdrains and Subdrains: Backdrains and subdrains shall be provided in fill as recommended by the Geotechnical Consultant and shall be constructed in accordance with the governing agency and/or recommendations of the Geotechnical Consultant. The location of subdrains, especially outlets, shall be surveyed and recorded by the Civil Engineer. B. Top-of-slope Drainage: Positive drainage shall be established away from the top of slope. Site drainage shall not be permitted to flow over the tops of slopes. C. Drainage terraces shall be constructed in compliance with the governing agency requirements and/or in accordance with the recommendations of the Civil Engineer. D. Non-erodible interceptor swales shall be placed at the top of cut slopes that face the same direction as the prevailing drainage. VI. Erosion Control A. All finish cut and fill slopes shall be protected from erosion and/or planted in accordance with the project specifications and/or landscape architect's recommendations. Such measures to protect the slope face shall be undertaken as soon as practical after completion of grading. B. During construction, the contractor shall maintain proper drainage and prevent the ponding of water. The contractor shall take remedial measures to prevent the erosion of graded areas until permanent drainage and erosion control measures have been installed. VII. Trench Excavation and Backfill A. Safety: The contractor shall follow all OSHA requirements for safety of trench excavations. Knowing and following these requirements is the contractor's responsibility. All trench excavations or open cuts in excess of 5 feet in depth shall be shored or laid back. Trench excavations and open cuts exposing adverse geologic conditions may require further evaluation General Earthwork Specifications Page 5 ADVANCED GEOTECHNICAL SOLUTIONS, INC. by the Geotechnical Consultant. If a contractor fails to provide safe access for compaction testing, backfill not tested due to safety concerns may be subject to removal. B. Bedding: Bedding materials shall be non-expansive and have a Sand Equivalent greater than 30. Where permitted by the Geotechnical Consultant, the bedding materials can be densified by jetting. C. Backfill: Jetting of backfill materials to achieve compaction is generally not acceptable. Where permitted by the Geotechnical Consultant, the bedding materials can be densified by jetting provided the backfill materials are granular, free-draining and have a Sand Equivalent greater than 30. VIII. Geotechnical Observation and Testing During Grading A. Compaction Testing: Fill will be tested and evaluated by the Geotechnical Consultant for evaluation of general compliance with the recommended compaction and moisture conditions. The tests shall be taken in the compacted soils beneath the surface if the surficial materials are disturbed. The contractor shall assist the Geotechnical Consultant by excavating suitable test pits for testing of compacted fill. B. Where tests indicate that the density of a layer of fill is less than required, or the moisture content is not within specifications, the Geotechnical Consultant shall notify the contractor of the unsatisfactory conditions of the fill. The portions of the fill that are not within specifications shall be reworked until the required density and/or moisture content has been attained. No additional fill shall be placed until the last lift of fill is tested and found to meet the project specifications and approved by the Geotechnical Consultant. C. If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as adverse weather, excessive rock or deleterious materials being placed in the fill, insufficient equipment, excessive rate of fill placement, results in a quality of work that is unacceptable, the consultant shall notify the contractor, and the contractor shall rectify the conditions, and if necessary, stop work until conditions are satisfactory. D. Frequency of Compaction Testing: The location and frequency of tests shall be at the Geotechnical Consultant's discretion. Generally, compaction tests shall be taken at intervals approximately two feet in fill height. E. Compaction Test Locations: The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of the compaction test locations. The contractor shall coordinate with the surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations. Alternately, the test locations can be surveyed and the results provided to the Geotechnical Consultant. F. Areas of fill that have not been observed or tested by the Geotechnical Consultant may have to be removed and recompacted at the contractor's expense. The depth and extent of removals will be determined by the Geotechnical Consultant. General Earthwork Specifications Page 6 ADVANCED GEOTECHNICAL SOLUTIONS, INC. G. Observation and testing by the Geotechnical Consultant shall be conducted during grading in order for the Geotechnical Consultant to state that, in his opinion, grading has been completed in accordance with the approved geotechnical report and project specifications. H. Reporting of Test Results: After completion of grading operations, the Geotechnical Consultant shall submit reports documenting their observations during construction and test results. These reports may be subject to review by the local governing agencies. Project:P/W 2005-01Report:2005-01-B-2Date:June 2020PLATE 1Geologic and Site Exploration PlanLEGEND:AfArtificial Fill(Tsa)Santiago Formation(Bracketed where buried)Geologic ContactAf(Tsa)Tsa20’Approximate Limits ofSurficial FailureApproximate Limits ofSmaller Surficial SlumpApproximate Limitsof French DrainsGEOLOGIC AND SITE EXPLORATION PLANGeologic Cross-SectionApproximate location of exploratoryboringsHA-1NUMEROUS SURFICIAL FAILURES ON SLOPEHA-1HA-2HA-5HA-3AA’HA-4CROSS-SECTION A-A’SCALE 1”=20’ H&V*Topography estimated from Rough Grading Plan and may not represent current topographyHA-1El CaminoRealAA’200220240180ELEVATION (FEET)260FenceTsaExisting GradeafCurrent Grade Post Failure?HA-3HA-4HA-5