CEMEX Eliot Quarry
Geotechnical Characterization Report
Alameda County, California
May 7, 2015
CEMEX Eliot Quarry
Geotechnical Characterization Report
Alameda County, California
May 7, 2015
Project No. GT13-16
Prepared for:
CEMEX 5180 Golden Foothills, Parkway El Dorado Hills, California 95762
7400 Shoreline Drive, Ste. 6 Stockton, California 95219 Tel: 209-472-1822 Fax: 209-472-0802 www.kanegeotech.com THIS PAGE INTENTIONALLY LEFT BLANK
KANE GeoTech, Inc. -ii- EXECUTIVE SUMMARY
CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California
In response to Alameda County reclamation requirements for Eliot Quarry, CEMEX, Inc. was asked to assess the stability of pit slopes in the areas of Lakes A , B, and J. KANE GeoTech, Inc. was retained to perform the pit stability study under reclaimed conditions as presented in the CEMEX reclamation plan amendment. The study included drilling and logging 22 boreholes, performing in-situ and laboratory testing for geomaterial strength parameters, and analyzing slope stability using current standard of practice methods for static and seismic conditions following the guidelines set forth in the California Geological Survey’s 2008 Special Publication 117A.
The Safety Factor is the ratio of the resistance that can be mobilized to the driving forces that would cause a failure. Geomaterials have an inherent strength called shear strength to resist failure. Characteristics in slopes that govern the driving forces are the weight of the geomaterials, slope and strata angles, the presence of water, and accelerations due to a seismic event. For slope stability in general, a Safety Factor of 1.5 for static and 1.0 for seismic conditions are accepted as standard-of-practice minimum values. A safety factor higher than the minimum is not a guarantee that slope failure is impossible. However, it does indicate that the possibility has been found from experience to be negligible. For seismic conditions, a pseudo-static approach is used in which the weight of the material is increased by a seismic coefficient to simulate the effects of additional ground acceleration. The Standard of Practice is described in “2008 Guidelines for Evaluating and Mitigating Seismic Hazards in California” Special Publication 117A, California Department of Conservation. A seismic coefficient of 0.21 was prescribed for Lake A and 0.16 for Lake B. Because of Lake J’s close proximity to Stanley Boulevard, the conservative 0.21 seismic coefficient was utilized for the analyses. The required factors of safety under static and seismic conditions are achieved when slopes are at a 2H:1V with the exception of slopes in Lake J which would need to transition to a 3H:1V gradient at 150-ft MSL for the final 20-ft of mining to 130-ft MSL. Current plans do not call for Lake A to be mined.
There are five documents contained in this project submittal. They are:
1. Geotechnical Characterization Report. This document which describes all the geotechnical background information used in preparation of the analyses.
2. Geotechnical Characterization Appendices. The Appendices document contains all available laboratory information for the geotechnical investigations in the Chain of Lakes. It also contains copies of all reports, technical memos, and maps related to the lakes.
3. Lake A Focus Report. This report contains the results of the analyses for Lake A.
4. Lake B Focus Report. This report contains the results of the analyses for Lake B.
5. Lake J Focus Report. This report contains the results of the analyses for Lake J.
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KANE GeoTech, Inc. -iv- TABLE OF CONTENTS
EXECUTIVE SUMMARY...... -iii-
TABLE OF CONTENTS...... -v-
1. INTRODUCTION...... 1 1.1 Purpose...... 2 1.2 Scope of Work...... 2
2. SITE DESCRIPTION...... 3 2.1 General...... 3 2.2 Site Geology...... 3 2.2.1 Site Lithology...... 3 2.2.2 Site Hydrogeology...... 4
3. BACKGROUND...... 12
4. GEOTECHNICAL INVESTIGATION...... 19 4.1 Field Study...... 19 4.2 Laboratory Study...... 23 4.3 Slope Stability Analyses...... 23 4.4 Review of Slope Stability Methods Used in Analyses...... 25 4.4.1 Simplified Bishop Method...... 25 4.4.2 Sarma Method...... 25 4.5 Seismic Analysis...... 26 4.5.1 Special Publication 117A (SP117A) Criteria...... 26 4.5.2 Seismic Analysis Method...... 27
5. RESULTS...... 33
6. SUMMARY OF WORK PERFORMED BY KANE GEOTECH...... 33
7. CONCLUSIONS AND RECOMMENDATIONS...... 34
8. REFERENCES & BIBLIOGRAPHY...... 34
9. LIMITATIONS...... 38
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KANE GeoTech, Inc. -vi- 7400 Shoreline Drive, 1441 Kapiolani Boulevard, Suite 6 Suite 1115 Stockton, California 95219 Honolulu, Hawaii 96814 209-472-1822 Phone 209-472-0802 Fax 808-356-2668 Phone [email protected] www.kanegeotech.com
CEMEX Eliot Quarry
Geotechnical Characterization Report
Alameda County, California
Project No. GT13-16
1. INTRODUCTION KANE GeoTech, Inc. (KANE GeoTech) was retained by CEMEX, Inc. (CEMEX) to investigate Eliot Quarry, Livermore, California. This report was prepared by KANE GeoTech for its client, CEMEX of El Dorado Hills, California, to provide information on the assessment of the stability of the slopes of the quarry. CEMEX is proposing a reclamation plan amendment which will take place in Lakes A, B, and J, Figure 1. It is noted that Lakes A and B will be the a part of the Chain of Lakes system controlled by the Alameda County Flood Control and Water Conservation District, Zone 7. Lake J is included in the reclamation plan, but will not be a part of the Chain of Lakes.
Figure 1. Air photo of the Chain of Lakes complex in Livermore, California. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 2 The quarry is located between Stanley Boulevard and the Arroyo Del Valle. Lakes A and B are transected by Isabel Avenue. Access to the quarry is located on Stanley Boulevard which is adjacent to Lake J and parallels Arroyo Del Valle. Figures 1 and 2 show the location of the CEMEX Eliot Quarry.
This Report reflects the reviews and comments by the County of Alameda’s geotechnical reviewer, ENGEO, Inc. (ENGEO) of San Ramon, California.
Figure 2. Project location near San Francisco, California.
1.1 Purpose The purpose of this report is to provide the background information and results of all of the prior studies, field testing, and lab analyses that are used in the Lake Evaluation Reports at Eliot Quarry (KANE GeoTech, 2015a, 2015b, 2015c). The Lake Evaluation Reports are where the results of the slope stability analyses are presented for each lake.
1.2 Scope of Work The scope of services provided by KANE GeoTech included the following:
1. Literature Review. KANE GeoTech reviewed existing literature and other archived materials such as geotechnical investigations, maps, and aerial images. CEMEX made available previous reports and exploration drill logs for the site. A stratigraphic history of the area was constructed and used to interpret the depositional environment of the Livermore Formation.
2. Geotechnical Investigation. CEMEX retained a drilling contractor to drill and sample the site. KANE GeoTech performed pocket penetrometer strength testing and collected grab samples for further analyses. Split spoon tests were obtained by the driller at locations and depths determined by KANE GeoTech in the field depending on the strata encountered.
3. Materials Testing. Laboratory testing was performed on samples to evaluate moisture content and density, Atterberg limits, grain size, USCS identification, and shear strength.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 3 4. Engineering Analyses. Final slope configurations were analyzed for stability using standard of practice analyses tools including slope stability analysis software.
5. Report of Findings. KANE GeoTech provides this Report of Findings stamped by a licensed California civil engineer experienced in slope stability. This Geotechnical Characterization Report contains background information and results of all of the prior studies, field testing, lab analyses used in the Lake Evaluation Reports, and an explanation of the data for each lake to conduct the slope stability analyses consistent with standards of practice (2015a, 2015b, 2015c). An Appendix is included as a separate document with all supporting documentation. The three Lake Evaluation Reports contains a summary of each investigation, analyses results, calculated safety factors for the slopes, and conclusions.
2. SITE DESCRIPTION 2.1 General Eliot Quarry is located at latitude 37E39'19" N, longitude 121E48' 20" W, Alameda County, California, in the Altamont 7½’ Geologic Quadrangle. Surface elevations along Lakes A, B, and J vary between 380-ft and 450-ft MSL. The nearest fault is the Las Positas fault located about two miles to the southeast. The nearest major fault is the Greenville Fault (about 11.5-mi to the southwest. The pit slopes are generally bare and covered with light vegetation in places. Eucalyptus trees are adjacent to the slopes at some locations.
2.2 Site Geology 2.2.1 Site Lithology The original surficial soil mapping was completed by the Soil Conservation Service (SCS, 1957) as mostly Holocene with some Pleistocene and Pliocene Alluvium. The Holocene and Pleistocene epochs are the most recent geologic time periods. Alluvium is a geologic term for material that has been deposited by flowing water, usually caused by large storm events, and often contains clay, silt, sand, and gravel. Flowing water transports the sediment from high to low topographic areas, where the stream energy is dissipated, depositing the sediment. Geologic deposits are described by their relative age to surrounding earth materials.
A detailed investigation of ground water in the Livermore and Sunol Valleys was performed by Department of Water Resources (DWR) (1966). The investigation was conducted by the DWR and gave a detailed description of the Livermore Valley’s lithology. The report further explained the characteristics of the Upper and Lower Livermore gravels, as well as the overlying Quaternary Alluvium. It also explained that a high percentage of the Alluvium was eroded and transported Upper Livermore sediment, which is why it was often difficult to differentiate between the two.
More recent studies done in the Livermore Valley have identified three units present within the Livermore Formation. These include the Lower Livermore, Upper Livermore, and Quaternary Alluvium. CEMEX Eliot Quarry is mining Quaternary alluvium and possibly the Upper Livermore Formation gravels that underlie much of the Livermore Valley.
The Lower Livermore unit contains deposits ranging in age from middle Pliocene to lower Pleistocene, with measured surface stratigraphy containing approximately 50% sand, 40% silt and
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 4 mud, and 10% pebble to cobble sized gravel. Tuff-bearing beds are also inter-layered throughout (Barlock, 1989). These beds are well defined by their grain size indicating a change in energy of the depositional environment, and in this case, a stream. The type of stream present at the time of deposition was a Platte-type braided stream flowing from the southwest, with the gravel source generally being the Altamont area (Barlock, 1989). This braided stream was the cause of the repeating, discontinuous, sedimentary beds which lead to lenses of silt, sand, clay, and gravel. During the constant deposition and erosion of the Lower Livermore, there was volcanic activity to the north, which resulted in the discontinuous ash deposits. Subsequently, a gentle uplifting developed in the Livermore Valley due to regional tectonics. This caused the stream flow to change direction, with the source in the Coast Range, south of the Altamont area. This change in provenance marks the base of the Upper Livermore marked by an abrupt change in lithology accompanied by an erosional unconformity at the top of the Lower Livermore.
The Upper and Lower Livermore units were deposited during the early Pleistocene by braided streams of various energy levels. The source area for the Upper Livermore is believed to be the Franciscan Complex to the south and east of the Livermore Valley. The clasts present in the strata consist of a high percentage of greywacke (Barlock,1989). Repeating and discontinuous clay, silt, sand, and gravel beds present within the unit provide the evidence of a braided stream depositional environment. These features are similar to those in the Lower Livermore but there is less clay and silt present in the Upper Livermore. Although it may appear superficially gravelly, close examination reveals an abundance of impermeable fines.
The United States Geological Survey (USGS) investigators used the gravels around Livermore to construct a geologic history of the area. USGS reviewed previous geological maps and studies, conducted field work, and compiled results in an open-file U.S. Geological Survey report. The report detailed braided stream depositional environments, tuff deposits, discontinuities by means of erosional surfaces, an unconformity seen by an abrupt lithology change between the Upper and Lower Livermore units, and overbank deposits. No mention of lacustrine deposits was included in the report. (1989)
The Quaternary deposits mined at Eliot Quarry consist of clay, silt, sand, and gravel (Wagner, 1990).These deposits are similar to those of the Upper Livermore. A significant amount of the Quaternary alluvium consists of eroded and transported Upper Livermore sediment. For this reason, it is difficult to differentiate between the two, other than by a gradual grain size transition seen in some areas.
2.2.2 Site Hydrogeology The information presented in this section has been summarized primarily Alameda County Flood Control and Water Conservation District Zone 7 (2011), Jones and Stokes (2005), and other Zone 7 data. Additional interpretation is also provided based on borehole data obtained by CEMEX in 2013.
The CEMEX Eliot Quarry is located within the Livermore-Amador Valley, an east-west trending inland alluvial basin located in northeastern Alameda County (Figure 3). An alluvial basin is a valley that has been filled with sediments deposited predominantly by streams and rivers. The basin is surrounded primarily by north-south trending faults and hills of the Diablo Range. The
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 5
Figure 3. Livermore Valley Groundwater Basin (Zone 7 Water Agency, 2011).
Livermore-Amador Valley encompasses approximately 42,000 acres, is about 14 miles long (east to west), and varies from three miles to six miles wide (north to south). The Livermore Valley Groundwater Basin is located in the central part of the Livermore-Amador Valley. The Main Basin is a part of the Livermore Valley Groundwater Basin that contains the highest-yielding aquifers and the best groundwater quality. Lake A and Lake B are located within the southeast corner of the Main Basin.
The Livermore-Amador Valley is partially filled with alluvial fan, stream, and lake deposits, collectively referred to as alluvium. The alluvium in the valley consists of unconsolidated gravel, sand, silt, and clay. Alluvial fans occur where streams and rivers from hilly or mountainous areas enter a valley and deposit very coarse sediment, primarily sand and gravel. The silt and clay were deposited in floodplain areas or lakes that developed at different times across the basin. The alluvium is relatively young from a geologic perspective, being deposited during the Pleistocene and Holocene geologic epochs (younger than 1.6 million years old). In the west-central area of the basin, the alluvium is up to 800 feet thick, but thins along the margins of the valley.
The southeastern and central parts of the Main Basin area contain the coarsest alluvial fan deposits. These alluvial fan deposits were formed by the ancestral and present Arroyo del Valle and Arroyo Mocho. The coarse alluvial fan deposits are economically important aggregate deposits, which has resulted in the widespread aggregate mining in the Main Basin area. Recent investigations conducted on behalf of Zone 7 (2011) have been used to refine the interpretation of subsurface conditions based on specific stratigraphic depositional sequences, or the specific layering of the sediments that occur from changes in the conditions at the time the aggregate material was deposited. Drillhole data and aquifer pumping tests conducted by Zone 7 (2011)
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 6 show that in parts of Lake B and in the Lake J area, clay layers are generally not present, consistent with the alluvial fan depositional environment.
The aggregate materials present in the southeastern part of the Amador sub-basin were deposited by ancestral streams that flowed in the same areas from which Arroyo del Valle and Arroyo Mocho currently originate within the Livermore highlands to the south (DWR, 1966). While lakes formed intermittently in the central and western parts of the basin, the area south of Stanley Boulevard, in the current area of Lakes B, C, and D of the Chain of Lakes, and Lake J, was part of a large alluvial fan system emanating from the hills to the south (Alameda County Planning Department, 1979).
The ancestral stream channels for Arroyo del Valle and Arroyo Mocho were identified by DWR (1966). Figures 4 and 5 are copies of a part of Plates 7 and 6, respectively, from the DWR (1966) study of the geology of the Livermore Valley. Figure 4 shows the gross thickness of aquifer materials in the depth interval between 100-ft BGS and 200-ft BGS in the Amador sub-basin. The ancestral axes of the major stream depositional channels are also shown on Figure 4. In the area south of Stanley Boulevard and west of Isabel Avenue, the ancestral channel of Arroyo del Valle deposited as much as 90 feet of coarse-grained aquifer material within the 100-foot interval between 100-ft BGS to 200-ft BGS. The ancestral Arroyo del Valle channel depicted on Figure 4 is located along the northern and northeastern sides of Lake B. Figure 4 also indicates that the Quaternary Alluvium is not present in this depth interval east of Isabel Avenue and south of Alden Lane, in the area of Lake A.
Figure 5 shows the gross thickness of aquifer materials in the depth interval between the ground surface and 100-ft BGS in the Amador sub-basin. The ancestral axes of the major stream depositional channels are also shown on Figure 5. The approximate outline of the Eliot facility and the location of several boreholes are also indicated on Figure 5. Deposition associated with the ancestral Arroyo del Valle channel within the depth interval down to 100-ft BGS extends east of
Figure 4. Department of Water Resources, Evaluation of Groundwater Resources in Livermore, 100-200-ft below ground surface.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 7
Figure 5. Department of Water Resources, Evaluation of Groundwater Resources in Livermore, 0- 100-ft below ground surface.
Vallecitos Road. In the western part of Lake A, the eastern part of Lake B, along the north side of Lake B, and through Lake J, the coarse-grained aquifer deposits comprise over 90 percent of the material deposited by the ancestral Arroyo del Valle. It is also important to note that, while the ancestral stream channel follows the current stream channel in the Lake A area, the ancestral channel turned to the north in the Lake B area and then paralleled the current location of Stanley Boulevard.
In April 2013, CEMEX drilled and logged 22 boreholes at SMP-23. The boreholes were drilled using a Becker Hammer drill rig. The borehole locations are shown on Figure 6. Five boreholes were drilled along the west and south sides Lake A, 14 boreholes were drilled around the perimeter of and within Lake B, and three boreholes were drilled in the existing plant area. At Lake A the boreholes were drilled to depths of 110-ft below ground surface (ft BGS) to 200-ft BGS, corresponding to elevations of approximately 320-ft MSL down to 220-ft MSL. At Lake B the boreholes were drilled to depths of 200-ft BGS to 220-ft BGS within the pit and 280-ft BGS to 300- ft BGS around the perimeter, corresponding to elevations of approximately 136-ft MSL down to 96-ft MSL, except for the two shallow holes within the pit, which were drilled to 50-ft BGS and only reached an elevation of approximately 250-ft MSL. Boreholes BH2013(KGT)-14 through BH2013(KGT)-16, located in the Lake J area, were drilled to depths of 280-ft BGS to 290-ft BGS, corresponding to elevations of approximately 100-ft MSL to 90-ft MSL. Detailed borehole logs are provided in Appendix A.
Figures 7, 8, and 9 present Cross Sections A-A’, B-B’, and C-C’, respectively, for the Eliot Facility. The section locations are shown on each figure.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 8
Figure 6. Borehole Locations
Cross Section A-A’ (Figure 7) extends from the processing plant area and Lake J at the Eliot Facility, near Stanley Boulevard, toward the southeast through Lake B and along the south side of Lake A to Vallecitos Road. In the Lake A area, the sand and gravel deposits that constitute the Quaternary Alluvium are approximately 100 feet thick, as indicated in boreholes BH2013-18 through BH2013-21. The alluvium is underlain by deposits that consist of gray and blue clays, partially-cemented gravels, and tuffs (volcanic ash). The deposits that are present beneath the alluvium are consistent with the description of the Lower Livermore Formation as defined by Barlock (U.S. Geological Survey, 1989a). The relatively thin Quaternary Alluvium in the Lake A area was also identified by DWR (1966), as indicated on Figures 4 and 5, which do not show the presence of alluvial deposits from ancestral Arroyo del Valle east of Isabel Avenue in the depth interval from 100-ft BGS to 200-ft BGS, but do show the occurrence of these deposits and the course of the ancestral streambed in the depth interval from the ground surface down to 100-ft BGS.
In the area of Isabel Avenue, between boreholes BH2013-17 and BH2013-1, the thickness of the sand and gravel deposits of the Quaternary Alluvium become much thicker due to the presence of a major erosional unconformity. As indicated on Figure 7, the thickness of the alluvium is at least 300 feet in the area of Lake B. However, the total thickness is unknown because none of the boreholes drilled in the Lake B area encountered the base of the alluvium.
The depth ranges and interpreted lateral extent of clay and silt deposits within the Quaternary Alluvium that were encountered in the boreholes are also shown on each of the cross sections. These clay and silt deposits typically form aquitard units that separate the main groundwater aquifers within the main part of the Amador sub-basin. As shown on Figure 7, the clay and silt deposits under Lake B area primarily thin and discontinuous. The approximate depth range of the various aquifer and aquitard units identified by Zone 7 (2011) are indicated along the left side of
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Figure 7. Geologic Cross Section A-A’.
Cross Section A-A’ on Figure 7. It is readily apparent that there are not any continuous clayey aquitard units present across the entire area of Cross Section A-A’.
Cross Section B-B’, Figure 8, extends from near the southeast corner of the Main Silt Pond on the Eliot Facility toward the south-southeast along the northeast side of Lake B and eventually crosses Lake B near the east end of the pit, approximately 1,200-ft to 1,500-ft west of Isabel Avenue. The bottom of borehole BH2013-1 encounters the unconformity between the Quaternary Alluvium and the Lower Livermore Formation discussed above and shown on Figure 7. The Lower Livermore Formation was not encountered in BH2013-8 on the south side of Lake B, which was drilled to a depth that is 35-ft deeper than BH2013-1. The Lower Livermore Formation was also not encountered in boreholes BH2013-2 and BH2013-3 to the north-northwest of BH2013-1. Thus, BH2013-1 is interpreted to have encountered a ridge or “nose” on the surface of the unconformity that projects under Isabel Avenue in the location of that borehole. Field reconnaissance conducted by personnel from CEMEX and KANE GeoTech in May 2014 confirmed that the Lower Livermore Formation is not present in the east wall of Lake B (see Section 4.1).
The five boreholes drilled for CEMEX in 2013 that are shown on Figure 8 consist predominantly of sand and gravel. Clay or silt layers were not identified in BH2013-8. Clay or silt layers were also not identified in BH2013-2 below an elevation of 360-ft MSL. In boreholes BH2013-1 and BH2013- 3, relatively thin fine-grained layers were logged between at approximately 165-ft MSL and 175-ft
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Figure 8. Geologic Cross Section B-B’.
MSL, respectively, but these layers were not encountered in the nearest adjacent boreholes. Thus, the fine-grained layers that were encountered are discontinuous and very localized in extent.
The north end of Cross Section B-B’ (Figure 8) occurs at the borehole for the 13P well cluster drilled for Zone 7 in 2010. The 2013 boreholes drilled for CEMEX extended to a maximum depth of approximately 300 feet, or an elevation of 100-ft MSL. However, the 13P borehole was drilled to a maximum depth of 618 feet, or an elevation of -239-ft MSL, substantially deeper than the proposed maximum depth of mining in Lake B. As shown on Figure 8, silts or clays were not encountered in the 13P borehole between approximately 325-ft MSL and approximately 95-ft MSL, which is more than 50 feet below the proposed maximum mining depth for Lake B.
The borehole logs shown on Cross Section B-B’ (Figure 8) indicate a substantial lack of fine- grained units above an elevation of 100-ft MSL. Thus, there is no indication of the occurrence of any laterally continuous clay layers along the east and northeast side of Lake B within the proposed mining depth. This finding is consistent with the interpretation presented by DWR (1966), as shown on Figures 4 and 5. Cross Section B-B’ roughly follows the path of the ancestral Arroyo del Valle channel and represents the area where the thickest and most continuous deposits of coarse-grained material exist within the Amador sub-basin. The information presented on Figure 8 clearly demonstrates that there are no continuous clay layers in the area represented by Cross Section B-B’, along the east and northeast sides of Lake B.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 11 Cross Section C-C’, Figure 9, extends along the Arroyo del Valle channel and south side of Lake B eastward to the west end of Lake A. On the east side of this cross section, the major erosional unconformity between the Quaternary Alluvium and the Lower Livermore Gravels is present, as previously described in the discussion of Cross Section A-A’, above. On the west side of Isabel Avenue, at borehole BH2013-8, the ancestral Arroyo del Valle channel is present, as indicated by the complete lack of observed fine-grained silt or clay deposits. Farther to the west, thicker and more continuous silt and clay layers are present. The most continuous fine-grained layer occurs within the general range of 295-ft MSL down to 240-ft MSL. A shallower fine-grained zone, up to 40 feet thick, is also present to the south of the current Arroyo del Valle channel. In the interval between 250-ft MSL and 150-ft MSL, however, only thin, discontinuous fine-grained deposits are observed and there are not any laterally consistent clay zones present. The presence of the thicker and more continuous silt and clay zones at the west end of Cross Section C-C’ is consistent with the interpretations of DWR (1966). As shown on Figures 4 and 5, the percentage of coarse deposits present in the depth ranges between 100-ft BGS to 200-ft BGS and between ground surface and 100-ft BGS, respectively, decreases rapidly toward the southwest, away from the ancestral Arroyo del Valle channel.
Figure 9. Geologic Cross Section C-C’.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 12 3. BACKGROUND Eliot Quarry has received significant attention in the past, and as a result, there are numerous geotechnical studies available for review. The following were used as supporting sources for the current investigation. A summary of the more relevant material is presented below. Copies of all of the documents described in this section, and listed in the References in Section 8, are provided in the Appendix.
Journal of Geotechnical and Geoenvironmental Engineering(1997). “Slope Stability Analysis in Stiff Fissured Clays.”Stark, T.D. and Eid, H.T. April 1997. This report focused on the behavior characteristics of clay under pressure, and the tests required to obtain the shear strengths of clays. Stark and Eid performed different shear tests on clays to show the strength variation that exists. They also reported on the relationship between the secant friction angle and the soil index properties.
KANE GeoTech, Inc. “RMC Pacific Materials Eliot Plant Slope Monitoring Study, Reports 1-24.” Inclinometer Monitoring (2002 -2005) From April 2002 to January 2005, KANE GeoTech collected and examined data from the inclinometers installed in the northeastern slope of Lake A adjacent to Lakeside Circle. These inclinometer readings initially showed movement when the inclinometers were first installed. Over time, however, the displacement in the inclinometers slowed and by March 2003, movement seemed to cease altogether. It was suspected that the movement in the inclinometers which were close to the quarry was due to naturally occurring elastic rebound as material was removed from the pit. These reports also showed that the displacement recorded by the inclinometers was so small that it was below the error band threshold. Displacement below the thresholds indicated that it was impossible to separate any casing deformation from random errors and systematic instrument errors. According to KANE GeoTech, data plotted below the error band was unreliable. In other words, any recorded “movement” was essentially zero if the error band was not exceeded.
Berlogar Geotechnical Consultants (2003). “Geotechnical Investigation Pavement and Driveway Distress Lakeside Circle Livermore, Ca.” March 13, 2013. This report presented results and recommendations from an investigation of pavement and driveway distress in The Oaks residential development, where Lakeside Circle is located. The purpose of this investigation was to find the possible cause(s) for cracking in the asphalt and concrete in Lakeside Circle.
Berlogar summarized previous work done by Brown and Mills, Inc., Kleinfelder, Inc., Kier & Wright, and KANE GeoTech. Berlogar performed site reconnaissance between February and May of 2002. In May 2002, Berlogar measured pavement cracks that were roughly parallel to the quarry slope and compared the results with measurements made by Kleinfelder in January 2002. It appeared the cracks widened 1/8-in to 1/2-in. Twelve rotary wash borings, ranging in depth from approximately 95-ft to 200-ft, were drilled between February 4 and November 8, 2002 for subsurface exploration, and borelogs were recorded. In addition, the soil was classified, intervals sampled, and blow counts reported. The borings showed a sandy gravel at shallow depths which Berlogar designated as the Upper Sand and Gravel. In some borings, this deposit was underlain by a clay layer, designated as the Upper Clay, then underlain by the Lower Sand and Gravel. Some borings did not have the Upper Clay present. The Lower Sand and Gravel deposit, was
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 13 underlain by a silty clay and clayey silt designated at the Lower Clay. Finally, beneath the Lower Clay interbedded sand, gravel, and clay to the maximum drilled depth of 200-ft was encountered. Granular soils were dense to very dense and the clayey soils were very stiff to hard.
A waxy, highly plastic clay was encountered in some of the borings near the top of the Lower Clay. This clay was very stiff to hard and contained a significant amount of slickensided surfaces, and in some cases appeared to be sheared. This clay had a very high Liquid Limit and Plasticity Index. Laboratory tests were performed and resulted in a friction angle of about 7Eand a peak cohesion of approximately 1,600-psf to 1,900-psf. Torsional ring shear testing indicated that shear strength of the waxy clay will decrease with the increase of shear deformation.
Exposed material was mapped by a field geologist along the slope located immediately southwest of Lakeside Circle. No visible signs of slope instability were noted on the slope.
Street monuments surveys were made between January 2000 and January 2003 by Carlson Barbee and Gibson Inc. After approximately 12 months, these surveys appeared to indicate vertical and horizontal movements ranging from 1/2-in to 2-in. These movements were believed to be generally larger near the top of the quarry slope and gradually decreased to insignificant at a distance ranging 300-ft to 400-ft from top of the slope. The horizontal movement was observed to trend southwest. The magnitude and direction of vertical and horizontal movements measured were similar to those observed by Kleinfelder (2002) and Kier & Wright (2002).
Piezometers were installed at various depths in four of the boreholes and monitored for approximately one year. The results were reported in the Appendix of Berlogar’s report.
Inclinometer casings were installed to depths of 130-ft to 160-ft below the ground surface. These inclinometers, along with those installed by KANE GeoTech and Kleinfelder, were read between April 2002 to February 2003. Some inclinometers did not show any significant movement while others indicated sharp slope movements. It was observed that the movements were located near the top of what Berlogar described as the waxy clay layer.
Berlogar stated that the small and uniformly-distributed cracking observed in Lakeside Circle was a “signature” pattern that was often seen in relaxation and lateral stretching, and associated this with the shear strength reduction of the waxy clay. Berlogar believed this was a form of elastic deformation due to significant unloading from the excavation adjacent to and below the slope.
Alternatively, Berlogar reported that some of the noted pavement and driveway cracks may have been the result of ground subsidence due to significant drawdown of the groundwater in the vicinity of Lakeside Circle. It was believed that lowering the groundwater increased the effective stress of the soils and resulted in ground subsidence. It was also speculated that any settlement would take place within two years after dewatering and estimated the total subsidence to be 1-in to 3-in. Ground surveys done for this report showed that most of the estimated settlement had already taken place.
Berlogar performed slope stability analysis using the slope stability software program GSLOPE. The slope was modeled with different lengths of the waxy clay and different ground water
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 14 conditions. Under these conditions, Berlogar determined the existing slopes were not stable under static and seismic conditions. It was suggested that fill be placed at the toe of the quarry slope in Quarry Pit A (Lake A) to an approximate elevation of 400-ft MSL. Berlogar also presented the option of installing 3-ft diameter, 140-ft long, steel beam reinforced, concrete stitch piers within the limits of The Oaks development, but noted that this would be very expensive.
Berlogar concluded the report with a recommendation to continue monitoring the street monuments, slope inclinometers, and piezometers every two months for at least one year after the slope was adequately stabilized.
GEOMATRIX (2004). “Slope Stability Evaluation Calmat Company, dba Vulcan Materials Company, Western Division Quarries Q-4 and Q-40.” August 2, 2004. GEOMATRIX produced a geotechnical report for Vulcan Materials Company, which is located in the Livermore Valley. The stratigraphic geological information in this report was similar to KANE GeoTech’s model and interpretation of the area. Regional seismicity was also mentioned by GEOMATRIX. They referenced major faults within the area and postulated the probability of a major earthquake in the area occurring in the near future.
Cotton, Shires, & Associates, Inc. (2006). “Slope Stability Analysis Results and Supporting Documentation.” E0284 Technical Memorandum #12. This technical memorandum is a summary of a 2-D limit equilibrium slope stability analysis performed on Section 40+20' which is centered on Lakeside Circle. This analysis was done using the computer program UTEXAS3. Cotton, Shires, & Associates (CSA) stated that the mechanism of movement at Lakeside Circle is governed by the stress relief response of the surrounding earth to excavation of the quarry pit, in combination with a relatively flat-lying (up to 3E inclination) area- wide, previously sheared, clay layer that is at residual shear strength over 120-ft beneath Lakeside Circle. CSA reported that because the gravels had not reached their residual strength, the overall static factor of safety of the slope, including the gravels and the low resistance clay, could be above equilibrium and even as high as 1.5. However, it was postulated that local shearing of the weak clay layer continued to occur in a delayed, concentrated response to excavation. CSA termed the mechanism of movement at Lakeside Circle an “incipient landslide” due to uncertainty that there would be a sufficient reduction in the response to excavation with time to avoid damage to residential subdivision improvements. CSA also reported that due to the weak clay layer present at Lakeside Circle, seismic slope stability was a concern and was found to be lower than levels typically accepted under the current standard of care of the geotechnical industry for slopes that have the potential to impact residential areas.
CSA’s report included a model of their interpretation of the surface and subsurface geometry. They used this model along with aerial photos and borings from CSA, Berlogar, KANE GeoTech, and Kleinfelder to develop their geologic cross section and geologic model. By correlating all of the data, CSA concluded that rapid sedimentation within the late Quaternary Livermore Basin produced a thick Holocene braided stream deposit unconformably overlying thick late Pleistocene sediments. They believed that these sediments were lacustrine in nature. They also stated that these deposits were laterally extensive beneath Lake A, and contained both oxidized and unoxidized layers. Within the unoxidized clay layer, CSA observed an intensely sheared clay layer. It was reported that this layer had reached residual strength. This unoxidized sheared layer was
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 15 below what CSA referred to as a lacustrine marl. The marl was used as a marker bed indicating the top of the lacustrine deposits.
CSA concluded that the late Pleistocene lacustrine deposits were not flat-lying, but deformed into a series of low amplitude, northwest-plunging folds. The report stated that the unoxidized clay layer was laterally extensive, and the thickness of the sheared material increased on the northwest dipping limb of the anticline. The anticline was theorized to trend through the residential subdivision located north of Lake A. This shearing was reported to diminish along the fold axis. CSA believed the origin of the shearing was tectonic deformation from gravitational landsliding. The landsliding occurred prior to, or during, deposition of the overlying Holocene braided stream deposits of the Quaternary alluvium.
CSA’s Technical Memorandum 12 included the material properties used during their slope stability analysis. When modeling the sheared clay layer, CSA’s strength parameters were based on Torsional Ring Shear testing which measured the residual strength of the clay. By using this type of strength test, CSA indicated the clay had already reached its peak strength and any strength still present was residual.
The “incipient landslide” was reported to be within the sheared clay layer where CSA conducted the residual strength testing. At the initial stage (Stage Zero), the safety factor was 1.22. This result indicated a relatively stable slope. However, CSA believed that since a relatively small amount of total displacement had occurred, the full strength of the gravel in the toe and head regions had yet to mobilize. A limitation of the analysis was the assumption that the safety factor was equal on all portions of the sliding surface despite material type. In each slope stability analysis done by CSA, it appeared the only layer that could potentially cause the “incipient landslide” was a sheared, unoxidized clay layer. Therefore, they assumed that the clay was sheared earlier and was at residual strength at the time of pit development while the other materials were not. At locations where there was gravel, the safety factor was most likely higher than 1.0.
California Geological Survey (2008). “Guidelines for Evaluating and Mitigating Seismic Hazards in California.” Special Publication 117A. 2008. This report from the California Geological Survey had the objective to assist in the evaluation and mitigation of earthquake-related hazards for projects within designated zones. It can be used along with ASCE, 2002. Its purpose was to promote uniform and effective statewide implementation and mitigation elements of the Seismic Hazards Mapping Act. This report stated the requirements that a slope must meet in order to be considered safe. Previously, the standard of practice for seismic analyses was a recommendation to use a seismic coefficient of 0.10 for magnitude 6.5 earthquakes, and a seismic coefficient of 0.15 for magnitude 8.25 earthquakes. The acceptable safety factor was 1.15.
The limitation of this analysis was that the one meter of allowable displacement far exceeded current standards for occupied dwellings. The report noted that the previous methodology only peripherally accounted for differences in earthquake magnitudes and, as a result, would either be over- or under-conservative. The report explained the procedure to evaluate a seismic coefficient using the maximum horizontal acceleration, along with the distance to the nearest fault and
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 16 maximum earthquake magnitude. These parameters were then referenced to a published graph and an intermediate value determined. This value was then used to calculate the seismic coefficient used in the seismic analysis.
California Geological Survey. (2008). “Seismic Hazard Zone Report for the Livermore 7.5- Minute Quadrangle.” Seismic Hazard Zone Report 114. 2008. This CGS report consisted of different assessments of liquefaction, slope stability in an earthquake, and ground shaking. Liquefaction causes were examined along with potential landslide hazards found in the Livermore area. Newmark’s method, as described in SP117A (CGS, 2008), was used to determine yield acceleration and calculate a safety factor.
Cotton, Shires & Associates, Inc. (2009). “As-Built Report and Summary of Construction Inspection and Testing, Lakeside Circle Corrective Action Plan, Alameda County, California.” This report summarized the geologic investigation, slope stability analyses of the completed project, and descriptions of the construction and monitoring activities by CSA. A geologic investigation was necessitated by cracks that were found in the pavement in a portion of Lakeside Circle adjacent to Lake A in November 2001. CSA installed inclinometers and piezometers in the slopes and developed a geologic model for the quarry site. Generally, borings contained about 100-ft of sandy gravel, gravelly sand, along with silt and clay. Also present was an unoxidized clay layer that was highly plastic containing, in some areas, pelecypod and gastropod shell fragments. Unoxidized clay layers are indicative of sediments that were deposited in an oxygen-scarce environment, such as the bottom of a lake. Pelecypod and gastropods are two classes of mollusks that are widespread in saltwater and freshwater environments. The clay was sheared and exhibited polishing along with a weak clay gouge. Shearing was greatest in the center of the clay layer and diminished toward the boundaries. It was stated that the shearing most likely predated the excavation of the quarry pit since it was observed in borings for which no inclinometer movements were recorded. It was postulated that the sheared, unoxidized clay caused movement in the subsurface, i.e. if any sort of landslide occurred, this clay layer would have been the most likely plane of failure.
An anticline is a fold that is concave-down, while a syncline is a fold that is concave-up. CSA’s structural interpretation was that the clay formed a roughly east-west-trending anticline/syncline with inclinometer deflections showing on the down-dip limb of the anticline dipping into Lake A. The originally flat-lying layers were partially folded by tectonic forces to produce an uneven surface, like a crumpled piece of paper. CSA postulated that the clay layer (which was originally deposited as a relatively flat surface) was trending slightly downhill from Old Oak Road to Lake A. North of the anticline, the axis dips away from the pit and no deflections of the inclinometers were found. Likewise, where the axis of the anticline was beneath the floor of the pit and bedding dipped into the pit slopes, no deflection of the inclinometers was recorded. CSA also noted high pore water pressures within the unoxidized clay caused decreased effective stresses and lowered safety factors.
Finally, CSA noted that the rate of displacement of the inclinometers, though already small, had decreased further prior to any mitigation. This was attributed to the diminishing effects of stress relief after excavation of the pit material. It was hypothesized that the expansion of the material
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 17 was concentrated along the weak unoxidized clay layer:
Initial deflection along the sheared clay bed eventually led to partial mobilization of the strength of the overlying gravel that prevented slope instability from fully developing. As a result of this mobilized gravel strength, the rate of slope inclinometer deflection has diminished over time and before implementation of remedial measures. However, once the extent and properties of the sheared clay unit were determined, the static factor of safety of the northern quarry slope was calculated to be below 1.5, and under seismic loads, significant displacements were anticipated. Consequently, it was deemed necessary to design and implement mitigation measures to address the stability of the Lakeside block.
CSA used UTEXAS3 with Spencer’s method to determine safety factors against failure. The shear strength parameters given in Table 1 were used in modeling. Spencer’s method is a type of limiting equilibrium analysis. Limiting equilibrium analysis is based on a comparison of the forces acting to move a soil mass (gravitational pull on the material) versus the forces resisting that movement (shear strength of the soil). The ratio of these two forces is the safety factor. If the safety factor is greater than 1, the sum of the resisting forces is greater than the driving forces and the slope is stable as long as conditions do not change. If the safety factor is 1, then driving forces are equal to resisting forces and the slope is on the verge of failure, in a state of limiting equilibrium. If the safety factor is less than 1, it is assumed that failure will occur.
Cotton, Shires & Associates, Inc. (2011). “Monitoring Report No. 14.” E0284MW. June 22, 2011. In this report, data from slope inclinometers, piezometers, surface survey monuments, and crack extensometers were collected and recorded near Lake A and the Lakeside Circle area. Initially, the slope inclinometers showed incremental displacement of less than 0.04-in/yr. During November 2010, slope inclinometers CSA/SD-1, BGC-2, and BGC-9 indicated the incremental displacement rate had increased to between 0.12-in/yr to 0.22-in/yr. The incremental rate from the previous readings range from -0.01-in/yr to 0.01-in/yr.
Vibrating wire piezometers (VWPs) indicated the elevation of the piezometric surface of the confined aquifer unit below the sheared clay had risen above the pre-pumping piezometric surface elevation. Near depressurization wells, the elevation had risen above the well discharge lines. This was observed by visual inspection. They were submerged due to a rise in Lake A. As a result, discharge from depressurization wells was counteracted by the lake level being higher than the well outlets.
Most survey monuments showed little or no change over six months. However, some monuments showed an apparent subsidence of up to 1.1-in and apparent rebound of up to 0.4-in in others. Piezometric data showed that the surface of the confined aquifer below the sheared clay had risen since the previous data collection. Flow from the depressurization wells appeared to have been impacted by inundation of the discharge lines. CSA believed that there was a positive buttressing impact of a higher lake level on the stability of the “incipient landslide.” This was counteracted by the negative impact of higher pore pressure at depth. CSA recommended that the stability of the “incipient landslide” be re-analyzed to assess whether the positive buttressing effect of the higher lake level was enough to offset the negative pore pressure influence on slope stability. The outcome could have required the level of Lake A to be lowered to between 400-ft and 404-ft to re- establish the gravity flow from the depressurization wells.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 18 Monitoring of crack extensometers in Lakeside Circle was difficult because most were destroyed during placement of a fresh slurry coat over the pavement. The four that were still intact, out of the original fourteen, were located on the paved pedestrian path. These four extensometers showed the crack narrowing to 0.016-in.
CSA’s most recent slope inclinometer data showed that there was very little horizontal deflection since previous monitoring. These movements were well below the threshold of 1.1-in/yr set by CSA for responsive action. The two slope inclinometers located southwest of the former pit showed no significant additional deflection since completion of Stage Six and Seven of construction. Monitoring of the surface survey monuments at the time of Stage One had shown no consistent pattern of rebound or subsidence. All recorded movement was less than the precision of the survey monitoring method. In other words, no significant settling had been recorded. CSA recommended more extensometers be installed since all but four were destroyed in the new slurry coat application and also recommended continued monitoring.
Berlogar Stevens & Associates (2012). “Slope Stability Investigation, Lake B – Corrective Action Plan, SMP23 Quarry, Livermore, California.” Report to CEMEX, Inc., Pleasanton, California, October 30, 2012. Berlogar Stevens & Associates performed a slope stability investigation for quarry pit slopes for Lake B. The surface of the slopes was mapped by a geologist, and two borings were drilled to depths of 60-ft and 125-ft to determine subsurface conditions. Direct shear laboratory tests measured friction angles between 27E and 37E and cohesion between 40-psf and 1,100-psf for clayey sands and gravels. Undrained shear testing resulted in unconfined compressive strengths
TABLE 1. MATERIAL PARAMETERS USED FOR LAKE A SLOPE STABILITY ANALYSES (CSA, 2009).
Material Unit Weight Cohesion Friction Angle (pcf) (pcf) (deg)
Upper and Lower Gravel (fully 139 200 45 mobilized strength)
Upper and Lower Gravel (partially 139 25 12 mobilized strength)
Upper Clay 127 1500 27
Oxidized Silty Clay 130 1000 24
Unoxidized Sheared Clay 121 0 11
Unoxidized Sheared Clay Gouge 121 0 Non-linear (approx. 6)
Lower Confined Aquifer 133 1300 28
Compacted Pea Gravel Fill 134 0 Non-linear (approx. 40 to 51)
Compacted Pit Run Fill 145 100 39
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 19 of 2,100-psf to 3,300-psf. Laboratory parameters are summarized in Table 2. Slope stability analyses using the modified Bishop method were performed using a cohesion value of 200-psf and a friction angle of 50E for the gravelly deposits, and cohesion of 500-psf and a friction angle of 32E for the fine-grained soils. Berlogar et al. did not explain this discrepancy between the laboratory test results and the shear strengths used in the slope stability analyses. Berlogar performed a seismic slope stability analysis using the Recommended Procedures of Implementation of DMG Publication 117. Based on an allowable displacement threshold of 6-in for the slope, a magnitude 6.6 earthquake, 0.45-g maximum horizontal acceleration for bedrock from the Mount Diablo Fault located approximately 7-mi away, a seismic coefficient of 0.16 was calculated. The results of Berlogar’s slope stability analysis indicated static safety factors ranging from 1.68 to 2.61 and seismic safety factors ranging from 1.57 to 1.91. Based on Berlogar’s calculated seismic safety factors, the slopes proposed for Lake B were determined to be stable during a seismic event.
4. GEOTECHNICAL INVESTIGATION 4.1 Field Study Twenty-two borings were drilled, under the direction of CEMEX and logged for geotechnical purposes by KANE GeoTech personnel. In conjunction with KANE GeoTech’s slope stability investigation, a quarry reserve study was performed. Borings were advanced using a Becker hammer. The Becker hammer was chosen to provide direct sampling of subsurface material for the quarry reserve study. This drilling method used a 9-in double-walled, hollow pipe that was advanced by means of percussion. The depth of drilling was marked in 10-ft increments. Cuttings were removed with compressed air and concentrated into a cyclone with a wheel barrow beneath to collect and transport them into windrows.
The standard penetration test (SPT) was used for sampling within the hollow casing. It is a common in-situ test used to obtain strength and density values of soils. It also provides soil
TABLE 2. MATERIAL PARAMETERS USED FOR LAKE B SLOPE STABILITY ANALYSIS, (BERLOGAR, 2012).
Material Parameters Test Type Avg. Unit Cohesion Friction Weight (psf) Angle (pcf) (Deg)
Laboratory Results
Brown Gravel Direct 123 40 to 1,100 27 to 37 Shear
Brown Clay* 150 2,100 to 3,300 20
Parameters Used in Analyses**
Gravelly Deposits None 140 200 50
Silts & Clays None 130 500 32 *Shear strength determination method not reported **Unknown source, not noted in report.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 20 samples for laboratory testing. SPTs were carried out during drilling and the results recorded on borelogs. Blow counts (N-values) required to drive the samplers were recorded every 6-in. The N-values were corrected for depth according to Peck, et al. (1974). Table 3 shows the number and depth of the borings. Borelogs can be found in Appendix A and boring locations are shown in Figures 10a and 10b and Appendix D. Visual classification according to ASTM D2488 (Visual- Manual Procedure) of each soil stratum was made in the field by the engineer or geologist at the time the test holes were drilled. Samples for laboratory testing were obtained using a 3-in California modified split spoon sampler containing 2.5-in brass or steel tube liners. The samplers were driven by a hand operated 140-lb hammer with a 30-in drop. Samples were analyzed in the field for identification by color, relative density, cohesiveness, field moisture, and visual grain size determination. Brass sleeves were sealed with plastic end caps and labeled for transportation to the laboratory.
TABLE 3. DRILLING SUMMARY FOR CEMEX ELIOT QUARRY, ALAMEDA COUNTY, CALIFORNIA. BOREHOLES LOGGED BY KANE GEOTECH.
Boring Surface Boring Surface Borehole Location Depth Elevation Borehole Location Depth Elevation (ft) (ft MSL) (ft) (ft MSL)
BH2013 Lake B 280 416 BH2013 Lake B 220 320 (KGT)-1 (KGT)-11
BH2013 Lake B 300 405 BH2013 Lake B 280 376 (KGT)-2 (KGT)-12
BH2013 Lake B 295 401 BH2013 Lake B 300 412 (KGT)-3 (KGT)-13
BH2013 Lake B 295 397 BH2013 Lake J 280 370 (KGT)-4 (KGT)-14
BH2013 Lake B 280 378 BH2013 Lake J 290 390 (KGT)-5 (KGT)-15
BH2013 Lake B 280 380 BH2013 Lake J 290 390 (KGT)-6 (KGT)-16
BH2013 Lake B 300 392 BH2013 Lake A 200 421 (KGT)-7 (KGT)-17
BH2013 Lake B 300 401 BH2013 Lake A 130 411 (KGT)-8 (KGT)-18
BH2013 Lake B 200 300 BH2013 Lake A 125 424 (KGT)-9 (KGT)-19
BH2013 Lake B 50 304 BH2013 Lake A 110 432 (KGT)-10A (KGT)-20
BH2013 Lake B 50 304 BH2013 Lake A 120 438 (KGT)-10B (KGT)-21
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 21
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 22
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 23 Drilling in Lake A and overseen by Kane GeoTech in 2013 indicated that lacustrine clay was present on the Lake A side (eastern) of Isabel Avenue. However, visual inspection of the slopes in Lake B on the western side of Isabel Avenue by KANE GeoTech and CEMEX personnel on May 8, 2014 revealed that the clay is not laterally continuous through the face of the slope adjacent to Isabel Avenue. The discontinuous character is most likely due to erosional unconformities, as described by Barlock/USGS. Therefore, It was conservatively modeled as extending half the distance between Lakes A and B.
4.2 Laboratory Study Cooper Laboratories, Inc., Palo Alto, California, tested the clay samples collected by KANE GeoTech in order to obtain the undrained compressive strength and determine Atterberg limits for the soil. The soil properties determined by laboratory testing were used to perform slope stability analyses, discussed in the following section. Soil test results are given in Appendix B.
4.3 Slope Stability Analyses Slopes were analyzed using Geo5 Slope Stability analysis software (Fine Engineering Software, 2014). 21. Geo5 uses slope stability analyses methodologies that are standard of practice in the geotechnical field. It utilizes standard practice limiting equilibrium slope stability methods to calculate safety factors against sliding. To verify the validity of Geo5, KANE GeoTech recreated the models constructed by Cotton, Shires, and Associates (CSA), and produced verifiable results. For the Eliot Quarry analyses, the Bishop method was used for a circular failure plane and the Sarma method was used with polygonal failure planes.
The safety factor against failure is the ratio of driving forces versus resisting forces (e.g. material gravity weight vs. material strength respectively). When the resisting forces are exactly equal to the driving forces, the safety factor is 1.0 and a slope is said to be at the condition of limiting equilibrium. If the safety factor is less than 1.0, it is assumed that failure will occur. If the safety factor is greater than 1.0, stability is assumed and increases with an increase in the safety factor.
A minimum factor of safety of 1.5 is desired for permanent slopes such as road cuts and developments. For seismic conditions, slopes are generally modeled as pseudo-static bodies. That is, the static weight of the slope material is multiplied by a seismic coefficient and the analysis is repeated as in the static case. When conducting the seismic analyses for Eliot Quarry, the guidelines and requirements reported in California Special Publication 117A were followed. Material properties were selected using drained strengths for gravels as published by Berlogar (2012) from laboratory test data. Undrained compressive strengths for clays were used to determine shear strengths at each profile. Undrained strengths were used to better represent the actual in-situ conditions at the site. Undrained strengths for clays are commonly used in slope and foundation design where loads are applied faster than pore pressures dissipate from the clay. Results using the undrained strengths of clays are more conservative and likely to be more appropriate in this situation. In order to verify this for the Eliot site, slope stability analyses were run using drained strengths of soils with similar plasticity indices and clay fractions derived from Stark and Eid (1997), Figure 11
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 24
Figure 11. Comparison of published fully softened friction angles and proposed Relationship, (Stark, 1997).
Profiles were created using each borehole located near critical slopes based on the mining plan and proposed final elevation at each location. All the slopes were modeled with a 2H:1V, two feet of horizontal distance per foot of vertical distance change, with the exception of Lake J having a transition to a 3H:1V the final 20-ft of mining. Analyses results included circular failure planes. The profiles and output results for all lake analyses are presented in the Lake Evaluation Reports (2015a, 2015b, 2015c). Typical material parameters used in the analyses are shown in Table 4.
TABLE 4. TYPICAL PARAMETERS USED FOR SLOPE STABILITY ANALYSES Material Parameters Avg. Unit Weight Saturated Unit Weight Cohesion Friction Angle (pcf) (pcf) (psf) (Deg)
Clayey Gravel 134 139 200 45
Low Plasticity Clay 125 130 1400 24
Low Plasticity Silt 116 121 1000 31
Well Graded Sand 128 133 0 34
Pea Gravel Fill 114 129 0 37
High Plasticity Clay 122 127 1600 7
Sheared Clay, high plasticity 122 127 1600 7
Sheared Clay 116 121 0 5
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 25 4.4 Review of Slope Stability Methods Used in Analyses Each slope stability method measures the same ratio of resisting forces and driving forces but the results can vary due to different assumptions made and different conditions to satisfy equilibrium. The safety factor equation, Equation 1, is as follows:
Equation 1.
Where: FS = safety factor N = normal force on failure plane ö = friction angle of material c = cohesion l = length of failure plane T = gravity (body) forces causing failure
4.4.1 Simplified Bishop Method The simplified Bishop method (Coduto, 1998) neglects interslice shear forces and thus assumes that a normal force or horizontal force adequately defines the interslice forces (Bishop, 1955). The Bishop method includes interslice normal forces. The safety factor is defined as the ratio of the available resistance due to the shear strength of the soil to the driving body forces in the slope due to body forces and applied loads. It is determined by dividing the slope cross-section into slices, resolving forces on each slice to calculate the factor of safety, and summing all slice results over the entire slope. This safety factor is based on and satisfies moment equilibrium only.
4.4.2 Sarma Method The Sarma method (Sarma, 1975) is a method of the limit equilibrium analysis which can be used to determine the stability of slopes of various shapes. Sarma method is intended for non-circular failure surfaces, Figure 12. It uses the ratio of the resisting forces to the driving forces at the failure surface to calculate the safety factor. Through iterations, a series of failure surfaces are tested and the failure surface with the minimum ratio is the accepted safety factor for the slope and materials specified. The Sarma method determines slope stability by applying a horizontal acceleration to the material above the failure surface, and calculating the safety factor the soil mass has to the applied force. The soil parameters are reduced until a zero acceleration is required for failure. This method was developed by Sarma as part of research done for the U.S. Army Corps of Engineers (USACE) to predict deformation of earthen dams due to seismic loading. Sarma extended the research to calculating safety factors since he reasoned that as a mass of soil moves from no movement to failure during a seismic event, the mass must pass through acceleration where the safety factor is 1.0, that is, the point where the mass is at limiting equilibrium. He called this acceleration value the critical acceleration and labeled it kc. Sarma defines the factor of safety as the factor by which the strength of the material must be reduced to produce a state of limiting equilibrium which occurs when the strength of the driving forces equals the strength of the resisting forces. The Sarma method differs from other methods because the driving force is the k factor needed for the soil mass to be in limiting equilibrium. Other methods compute the ratio of
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 26 the total resisting force to the total driving force of the soil mass being evaluated. The Sarma method states that the k factor is determined explicitly by solving the equations for equilibrium for each of the constraints specified by the modeler. The Sarma method allows for non-vertical, non-parallel boundaries between slices where the other methods encourage but do not require vertical slices. The non-vertical slices make the arithmetic more difficult, especially for calculating moments or stresses. The Sarma method is the best option to use when slopes are difficult to model and contain thin zones of soil or fractures, for example, a mine-pit cut with high walls and weak zones.
Figure 12. Forces acting on individual slices in Sarma’s Method, (Sarma, 1975)
4.5Seismic Analysis The methods used in the seismic analyses described below were determined by Alameda County and their consultants ENGEO. A meeting was held in Hayward, California on February 3, 2014 with CEMEX, Alameda County, ENGEO, Lamphier-Gregory, and KANE GeoTech personnel to discuss detailed approaches to the seismic analyses. On May 5, 2014 another meeting was held at ENGEO’s office, San Ramon, California, to reach consensus on a seismic coefficient of 0.16 to be used in the analyses of Lake B.
4.5.1 Special Publication 117A (SP117A) Criteria KANE GeoTech performed an evaluation of seismic hazards at CEMEX Eliot Quarry as a part of its Slope Stability Investigation . The California Geological Survey Special Publication 117A (2008) was used to assess the seismic risks at Eliot Quarry.
Originally adopted in 1997, this document was last updated in 2008 to maintain consistency with the California Building Code. The latest edition of this document is in accordance with the Seismic Hazards Mapping Act of 1990 and is intended to be used for guidance when evaluating seismic hazards within California’s regulatory “Zones of required investigation.” The purpose of the Seismic Hazards Mapping Act is to protect public safety from the effects of strong ground shaking, liquefaction, landslides, or other ground failure, and other hazards caused by earthquakes. The minimum statewide safety standard established by SP117A
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 27 exists to reduce the risk of ground failure during an earthquake to a level that does not cause the collapse of buildings for human occupancy, but in most cases not to a level of no ground failure at all.
The Criteria for Project Approval as listed in SP117A is summarized as follows:
A. A project shall be approved only when the nature and severity of the seismic hazards at the site have been evaluated in a geotechnical report and appropriate mitigation measures have been proposed.
B. The geotechnical report shall be prepared by a registered civil engineer or certified engineering geologist, having competence in the field of seismic hazard evaluation and mitigation. The geotechnical report shall contain:
1. Project description. 2. A description of the geologic and geotechnical conditions at the site, including an appropriate site location map. 3. Evaluation of site-specific seismic hazards based on geological and geotechnical conditions, in accordance with current standards of practice. 4. Recommendations for appropriate mitigation measures. 5. Name of report preparer and signature of a certified engineering geologist or registered civil engineer, having competence in the field of seismic hazard evaluation and mitigation.
C. Prior to project approval, the lead agency shall independently review the geotechnical report to determine the adequacy of the hazard evaluation. Such reviews shall be conducted by a certified engineering geologist or registered civil engineer, having competence in the field of seismic hazard evaluation and mitigation.
4.5.2 Seismic Analysis Method The most direct approach to a seismic slope stability analysis is a pseudo-static approach in which an additional load is applied to the model as a horizontal static force based on the earthquake acceleration. This model is considered to be generally conservative and is the one most often used in current practice (SP117A,2008). A pseudo-static approach to seismic slope stability modeling was used at the project site. This approach requires the modeler to estimate parameters of PGA (peak ground acceleration) and earthquake magnitude in order to choose a value for the seismic coefficient, k. Prior to the 2008 update to California Geological Survey Special Publication 117A “Guidelines for Evaluating and Mitigating Seismic Hazards in California”, the standard of practice in performing seismic slope stability analyses was to choose values for k of either 0.10 or 0.15.
These values are based on the work of Seed (1979) in which he summarized the factors to be considered when evaluating dynamic stability of earth and rock fill embankments. Per his recommendations, a seismic coefficient of 0.10 for magnitude 6.5 earthquakes and 0.15 for magnitude 8.25 earthquakes are sufficient to ensure acceptable performance of earth embankments in seismic conditions.
In 2008, the California Geological Survey adopted new guidelines which offer guidance to the civil engineer or engineering geologist conducting seismic slope stability analyses. These new guidelines recognize that the recommendations by Seed (1979) allow acceptable seismic displacements of embankments on the order of one meter and only peripherally account for differences in earthquake magnitude and distance from the epicenter.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 28 In an effort to address these limitations, the new guidelines rely on the work of Blake et al. (2002) to account for variations in seismic acceleration experienced due to proximity to the earthquake epicenter as well as provide different levels of acceptable displacements.
Blake et al. (2002) and Stewart et al.(2003) sought to develop a “screening analysis procedure” based on a pseudo-static approach. The current guidelines were formulated by Blake et al. (2002).
The seismic coefficient, keq, is derived from: keq = feq * MHAr where MHAr = the maximum horizontal acceleration at the site. The formula for feq is given in Equation 2.
Equation 2.
Where:
• NRF = a factor that accounts for the nonlinear response of the materials above the slide plane • u = the displacement
• MHAr = maximum horizontal acceleration • D5-95 = the duration of strong shaking, a function of earthquake magnitude and distance of the epicenter from the analysis site
Blake et al. (2002) simplified the process of estimating feq for ranges of magnitude and distance by publishing sets of curves for two displacement (u) values, 5-cm and 15-cm. These curves are shown in Figure 13. The available methods of selecting a value of the maximum horizontal acceleration (MHAr) at the site, are listed in SP117A. These include Probabilistic Seismic Hazard Analysis and Deterministic Seismic Hazard Analysis. Both of these methods reference published data from the USGS and the CGS in selecting a site specific value for Peak Ground Acceleration (PGA) or MHA. The California Geological Survey published a seismic hazard zone report for the Livermore 7.5 Minute Quadrangle, Alameda County, California in 2008 which provides values of 0.49 PGA for the Eliot Quarry site, Figure 14.
In addition to providing a value for PGA, the Seismic Hazard Zone Report for the Livermore 7.5- Minute Quadrangle, Alameda County, California, 2008 provides a map of the predominate earthquake for Eliot Quarry which lists the magnitude and distance to the epicenter, Figure 15. Based on the PGA and earthquake magnitude established through the CGS Seismic Hazard
Report, feq values were selected by KANE GeoTech, Figure 16.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 29
Figure 13. Values of feq as a function of MHAg, earthquake magnitude, and fault distance for the threshold displacement of 2-in (5-cm) (top) and 6-in (15-cm) (bottom). After Blake et al. (2002).
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 30
Figure 14. Map of PGA, with project area circled.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 31
Figure 15. Map of predominant earthquake values, with project area circled.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 32
Figure 16. Value of feq used for seismic analysis.
The seismic analysis of the site by Berlogar (2012) was reviewed by Rockridge Geotechnical (2012), acting as a subconsultant to ENGEO. Berlogar used a seismic coefficient of 0.16. This calculated value was obtained based on an allowable displacement threshold of 6-in, a magnitude 6.6 earthquake and 0.45-g maximum horizontal acceleration from the Mount Diablo Fault located approximately 7-mi away.
KANE GeoTech originally performed seismic analyses at Eliot Quarry in accordance with the 2002 SP117, but, after review, subsequently performed analyses following the guidelines set forth in the 2008 SP117A. A calculated value for the seismic coefficient at the site using the guidelines of California Special Publication 117A was 0.19, based upon an allowable displacement threshold of 6-in (15-cm), a magnitude 6.6 earthquake and 0.49g maximum horizontal acceleration from the Calaveras Fault located approximately 15 miles away (per The Seismic Hazard Zone Report for
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 33 the Livermore 7.5-Minute Quadrangle, Alameda County, California 2008). This is expected to be the predominate earthquake at this location at 10% exceedance in 50 years.
At the meeting on February 3, 2014, the County reviewer, ENGEO and the project team discussed the applicability of the 2013 California Building Code (CBC) with the approach outlined in SP117A where slopes are in proximity to existing residential structures. The 2013 CBC includes a Maximum Credible Earthquake Geometric Mean Peak Ground Acceleration (PGAM) intended to be used for evaluation of liquefaction potential. It was agreed that the 2013 CBC is ambiguous in the application of the PGAM for seismic slope stability in the Lakes area since no liquefaction hazard exists. However, it was agreed that a conservative approach was to use the PGAM for the site for the evaluation of slope performance under seismic loading. The value of PGAM from the 2013 CBC was approximately 0.53g. This resulted in a pseudostatic coefficient of 0.21 when using SP117A. This value was considered appropriate for the Lake A slopes due to the short distance from the residential area of Lakeside Circle.
Both KANE GeoTech and the County reviewers agreed that a seismic coefficient of 0.16 was appropriate for the seismic analysis of the Lake B slopes. Lake B is not in close proximity to any occupied dwellings, and the seismic coefficient of 0.16 as used by Berlogar (2012) was used in the analyses. However, to maintain and extra margin of safety adjacent to Isabel Avenue (State Route 84), a seismic coefficient of 0.21 was used along the east side of Lake B. Although no residents, highways, or other sensitive features are located within 100 feet of Lake J, a seismic coefficient of 0.21 was used for the Lake J slope stability analysis to provide an overly-protective evaluation, due to the general proximity of Stanley Boulevard, Shadow Cliffs Lake, and the Main Silt Pond.
5. RESULTS According to SP117A, “Slopes that have a seismic factor of safety greater than 1.0 using a seismic coefficient from the screening analysis procedure of Stewart et al. (2003) can be considered stable.” KANE GeoTech evaluated the slopes in Lakes A, B, and J at Eliot Quarry. The County only prescribed a seismic coefficient of 0.21 for Lake A. Based on the County’s logic, and for consistency, KANE GeoTech decided to use 0.21 for the east side of Lake B and for Lake J. The County (including ENGEO) did not require the use of 0.21 anywhere outside of Lake A. A seismic coefficient of 0.16 was used for all other slopes in Lake B, also required by ENGEO. The higher seismic coefficient of 0.21 was used for areas that were considered by the County to be in close proximity to dwellings, such as Lakeside Circle. Lakes A, B, and J results can be found in the Lake A Evaluation Report, Lake B Evaluation Report, and Lake J Evaluation Report (2015a, 2015b, 2015c).
6. SUMMARY OF WORK PERFORMED BY KANE GEOTECH KANE GeoTech has submitted slope stability analysis parameters and their justifications to Alameda County for review. Summaries of work performed for each Lake are located in the Lake A Evaluation Report, Lake B Evaluation Report, and Lake J Evaluation Report (2015a, 2015b, 2015c).
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 34 7. CONCLUSIONS AND RECOMMENDATIONS Our analyses and review of the existing literature indicate that a completed slope profile of 2H:1V is sufficient for all the completed slopes in Lakes A and B. Lake J slopes will be acceptably stable with a 2H:1V slope with a transition to a 3H:1V slope at 150-ft MSL for the final 20-ft of mining to an elevation of 130-ft MSL. Detailed conclusions and recommendations for Lake A, B, and J can be found in the Lake Evaluation Reports (2015a, 2015b, 2015c).
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Alameda County Flood Control and Water Conservation District, Zone 7. (2012). “Comments on the Proposed Interim Mining and Reclamation Program Lake B, Cemex Eliot Plant,” SMP-23, Pleasanton, CA, June 2012.
Alameda County Flood Control and Water Conservation District, Zone 7. (2013). “RE: Rapid Drawdown in Lake B.” C. Winey email response to K. Spinardi, P.E., March 19, 2013.
ASCE (2002). “Recommended Procedures for Implementation of Dmg Special Publication 117 Guidelines for Analyzing and Mitigating Landslide Hazards in California.” Committee organized through the ASCE Los Angeles Section Geotechnical Group Document published by the Southern California Earthquake Center, June 2002.
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Berlogar Stevens & Associates (2012). “Slope Stability Investigation, Lake B – Corrective Action Plan, SMP23 Quarry, Livermore, California.” Report to CEMEX, Inc., Pleasanton, California, October 30, 2012.
Bishop, A.W. (1955). “The Use of the Slip Circle in the Stability Analysis.” NRC Research Press. Web. July 23, 2014
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Cotton, Shires, & Associates, Inc. (2004). “Permeability of Rocky Fill.” E0284 Technical Memorandum #1.
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Cotton, Shires, & Associates, Inc. (2004). “Geophysical Surveys South and North of Lake A.” E0284 Technical Memorandum #5.
Cotton, Shires, & Associates, Inc. (2004). “Lakeside Circle Investigation, Oversized Fill Material Sieve Analysis.” E0284 Technical Memorandum #7.
Cotton, Shires, & Associates, Inc. (2005). “Lakeside Circle Investigation, Oversized ’Belt Cut’ Fill Material Sieve Analysis.” E0284 Technical Memorandum #8.
Cotton, Shires, & Associates, Inc. (2005). “Lakeside Circle Investigation, New Oversized ‘Belt Cut’ Lab Tests and Preliminary Shear Strength Estimate.” E0284 Technical Memorandum #9.
Cotton, Shires, & Associates, Inc. (2006). “Results of Recent Exploratory Borings CSA/SD-36 and CSA/SD-37 at CEMEX Quarry.” E0284 Technical Memorandum #10.
Cotton, Shires, & Associates, Inc. (2006). “CEMEX-Eliot Quarry, Lake A, 3/8 to 4-inch State Rockfill.” E0284 Technical Memorandum #11.
Cotton, Shires, & Associates, Inc. (2006). “Slope Stability Analysis Results and Supporting Documentation.” E0284 Technical Memorandum #12.
Cotton, Shires, & Associates, Inc. (2007). “CEMEX- Eliot Quarry, Area 4, Gravity Depressurization Wells Program.” E0284 Technical Memorandum #13.
Cotton, Shires & Associates, Inc. (2011). “Monitoring Report No. 14." E0284MW. June 22, 2011.
Cotton, Shires, & Associates, Inc. (2007). “CEMEX- Eliot Quarry, Area 4, ½" Minus Pea Gravel Rockfill Testing.” E0284 Technical Memorandum #15.
Cotton, Shires, & Associates, Inc. (2007). “CEMEX- Eliot Quarry, Area 4, July 2007 Slope Stability Analysis of Section 40+20'.” E0284 Technical Memorandum #16.
Cotton, Shires, & Associates, Inc. (2007). “CEMEX- Eliot Quarry, Area 4, August 2007 Consolidation Settlement Analysis of Proposed Stages 1 through 6 Pumping Program.” E0284 Technical Memorandum #17.
Cotton, Shires, & Associates, Inc. (2007) “Revised Repair Concept Utilizing Pumped Depressurization Wells.” Letter to Treadwell & Rollo and Kleinfelder, July 16 2007.
Cotton, Shires, & Associates, Inc. (2007) “Revised Drawings and Specifications for Repair Concept Utilizing Pumped Depressurization Wells.” Letter to Treadwell & Rollo and Kleinfelder, August 31, 2007.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 36 Cotton, Shires, & Associates, Inc. (2007). “Response to Treadwell & Rollo Email of September 5, 2007.” Letter to Treadwell & Rollo and Kleinfelder, September 28,2007.
Cotton, Shires, & Associates, Inc (2007), “Clarification of Pumping and De-watering Concerns (from October 4, 2007 email).” Letter to Carol Mahoney, Zone 7 Water Agency. October 31, 2007.
Cotton, Shires, & Associates, Inc. (2009). “As-Built Report and Summary of Construction Inspection and Testing, Lakeside Circle Corrective Action Plan, Alameda County, California.” Report to CEMEX, Eldorado Hills, California by Cotton, Shires, and Associates, Inc., Los Gatos, California, December 23, 2009.
Cotton, Shires, & Associates, Inc. (2011). “Reappearance of Pavement Cracks.” E0284MA. July 21, 2011.
Cotton, Shires, & Associates, Inc. (2011). “Reanalysis of ‘As Built’ Slope Stability.” E0284MA. August 24, 2011.
County of Los Angeles Department of Public Works. (2013). “Manual for Preparation of Geotechnical Reports.” County of Los Angeles Public Works. July 1, 2013.
Department of Water Resources. (1966). “Livermore and Sunol Valleys: Evaluation of Ground Water Resources.” Bulletin No. 118-2. Appendix A: Geology. August 1966.
Department of Water Resources. (2011). “Hydrostratigraphic Investigation of the Aquifer Recharge Potential for Lakes C and D of the Chain of Lakes, Livermore, California.” May 2011.
Earthwork (1991). “Proposed Lake D Berm.” Prepared for Lonestar Sand and Gravel Pits. Addressed to Peter Cotter. April 1991.
ENGEO (2012). Personal Communication: Seismic Coefficient Review. Telephone conversation, May 2012.
ENGEO. (2013). “Peer Review of Slope Stability Investigation”. October 21, 2013.
ENGEO. (2014). “Second Peer Review of Slope Stability Investigation”. January 16, 2014.
Fine Engineering Software (2014). “Geo5 Geotechnical Software Suite User’s Manual.” Fine spol. s r.o., Zaverka 12 169 00 Praha 6, Czech Republic.
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Hunt, R. E. (1984). Geotechnical Engineering Investigation Manual. McGraw-Hill Book Company, New York.
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Jones and Stokes (2005). “Groundwater Management Plan for Livermore-Amador Valley Groundwater Basin.” Jones and Stokes Associates, Inc., Report prepared for Zone 7 Water Agency, Alameda, California.
KANE GeoTech (2002-2005). “RMC Pacific Materials Eliot Plant Monitoring Reports 1-24.” Inclinometer Monitoring. April 14, 2002- February 8, 2005.
KANE GeoTech (2007). “Eliot Quarry Levee Investigation.” Final Report. December 26, 2007.
KANE GeoTech. (2013). “Lake B Investigation.” Letter to Peter Cotter. February 5, 2013.
KANE GeoTech. (2013) “Lakes A and B Slope Stability Investigation.” Executive Summary and Report. June 11, 2013.
KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 37 KANE GeoTech. (2013) “Lakes A and B Slope Stability Investigation.” Volume II Appendices. June 11, 2013
KANE GeoTech. (2013) “Lakes A and B Slope Stability Investigation.” Executive Summary and Report. November 18, 2013. (Revised).
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KANE GeoTech. (2013) “Lakes A and B Slope Stability Investigation.” Volume II Appendices. November 18, 2013. (Revised)
KANE GeoTech (2014). “Lakes A and B Slope Stability Investigation.” Second Review Comment Responses. January 31, 2014.
KANE GeoTech (2015a). “Lake A Evaluation Report.” March 6, 2015.
KANE GeoTech (2015b). “Lake B Evaluation Report.” March 6, 2015.
KANE GeoTech (2015c). “Lake J Evaluation Report.” March 6, 2015.
Kier & Wright Civil Engineers & Surveryors, Inc. (2002) “Lakeside Circle Monitoring”. October 10, 2002.
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Kleinfelder (2002). “Data Summary of Survey Measurements Performed at Lakeside Circle.” December 2, 2002.
Krout, C.K. (2005). “Response to Comments, Initial Study and Proposal to Adopt a Mitigated Negative Declaration for Amendment to SMP-16.” Memo to Bruce Jensen of Alameda County. May 9, 2005.
Mikkelsen, E. (2005). “Tech Memo RE: Data Review and Accuracy of Inclinometer Data.” GeoMetron Inc PS letter to Darrell Brownlow of CEMEX. November 16, 2005.
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KANE GeoTech, Inc. CEMEX Eliot Quarry Geotechnical Characterization Report Alameda County, California Page 38 Spinardi, K. and Cotter, P. (1994). “Permit Application for Time Extension of Q-76.” RMC Lonestar Eliot Plant. November 2004.
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9. LIMITATIONS The analyses, conclusions and recommendations contained in this report are based on the site conditions observed by KANE GeoTech and derived from the information provided. If there is a substantial lapse of time between the submission of this report and the start of any work at the site, or field conditions have changed due to natural causes, mining, or construction operations at or adjacent to the site, we urge that this report be reviewed to determine the applicability of the conclusions and recommendations considering the changed conditions and time lapse. This report is applicable only for the project and sites studied. After three years, KANE GeoTech should be consulted if this report is used in regard to any proposed changes in the area.
Our professional services were performed, our findings obtained, and our recommendations proposed in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties either expressed or implied. Findings and statements of professional opinion do not constitute a guarantee or warranty, expressed or implied.
KANE GeoTech, Inc.
William F. Kane, PhD, PE President California Registered Civil Engineer No. 55714
KANE GeoTech, Inc.