GEOTECHNICAL STUDY REPORT PROPOSED WATER STORAGE TANK WATER SYSTEM IMPROVEMENT WALNUT GROVE, CALIFORNIA. Prepared for: MWH AMERICAS INC.

Transcription

1 GEOTECHNICAL STUDY REPORT PROPOSED WATER STORAGE TANK WATER SYSTEM IMPROVEMENT WALNUT GROVE, CALIFORNIA Prepared for: MWH AMERICAS INC Prepared by: NOVEMBER 2012

2 GEOTECHNICAL STUDY REPORT PROPOSED WATER STORAGE TANK WATER SYSTEM IMPROVEMENT WALNUT GROVE, CALIFORNIA AGS Job No Prepared for: MWH AMERICAS INC Prepared by: NOVEMBER Freelon Street, San Francisco, California # Phone (415) # Fax (415)

3 TABLE OF CONTENTS PAGE NO. 1.0 INTRODUCTION GENERAL PROJECT DESCRIPTION WORK PERFORMED Review of Available Data Field Exploration Geotechnical Laboratory Testing Engineering Analyses and Report Preparation FINDINGS SITE CONDITIONS GEOLOGY FAULTS AND SEISMICITY SUBSURFACE CONDITIONS SOIL CORROSIVITY GROUNDWATER FLOOD INSURANCE RATE MAP CONCLUSIONS AND RECOMMENDATIONS GENERAL SEISMIC DESIGN CONSIDERATIONS General Fault Rapture Hazard Maximum Earthquake Estimated Earthquake Ground Motions Deterministic Methods Probabilistic Methods CBC Seismic Design Criteria Design Earthquake Walnut Grove Water System i November 2012

4 TABLE OF CONTENTS PAGE NO Vertical Acceleration Liquefaction Hazard Consequences of Liquefaction Seismically-Induced Settlements Lateral Deformation Liquefaction Mitigation EXCAVATION AND EARTHWORK Site Preparation Overexcavation Fills and Backfills Temporary Excavations Dewatering PIPELINES General Earth Loads Surcharge Pressures Modulus of Earth Reaction Thrust Resistance Trench Width Pipe Bedding Trench Backfill FOUNDATIONS General Soil Improvement Shallow Foundations Deep Foundation System General Deep Foundation Recommendation Walnut Grove Water System ii November 2012

5 TABLE OF CONTENTS PAGE NO. 3.6 RESISTANCE TO LATERAL LOADS Shallow / Mat Foundations Deep Foundations SETTLEMENT Static Settlements Seismically-Induced Settlements CORROSION POTENTIAL CONSTRUCTION CONSIDERATIONS General Effects on Adjacent facilities Geotechnical Services During Construction CLOSURE REFERENCES TABLES TABLE 1 - FAULT SEISMICITY... 6 TABLE 2 - SEISMIC CRITERIA TABLE 3 - SPECTRAL ACCELERATIONS TABLE 4 - SUMMARY OF LIQUEFACTION MITIGATION TECHNIQUES TABLE 5 - ESTIMATE ALLOWABLE COMPRESSION AND UPLIFT CAPACITIES OF 14-INCH SQUARE DRIVEN PILES TABLE 6 - ESTIMATE OF PRIMARY AND SECONDARY STATIC SETTLEMENTS PLATES PLATE 1 SITE LOCATION MAP PLATE 2 BORING LOCATION MAP PLATE 3 EARTH LOAD COEFFICIENTS FOR PIPELINE DESIGN Walnut Grove Water System iii November 2012

6 TABLE OF CONTENTS PAGE NO. PLATE 4 VERTICAL SURCHARGE PRESSURES PLATE 5 LATERAL SURCHARGE PRESSURES POINT AND LINE LOADS PLATE 6 LATERAL SURCHARGE PRESSURES AREAL LOADS PLATE 7 RESPONSE TO LATERAL LOADING APPENDICES APPENDIX A FIELD EXPLORATION AND SAMPLING APPENDIX B GEOTECHNICAL FIELD AND LABORATORY TESTING APPENDIX C CORROSIVITY TESTING APPENDIX D LIQUEFACTION ANALYSIS Walnut Grove Water System iv November 2012

7 1.0 INTRODUCTION 1.1 GENERAL This report presents the results of the geotechnical study conducted by AGS for the proposed water storage tank as part of California American Walnut Grove Water System (WGWS) Improvement project, in Walnut Grove, California. The study was performed to develop geotechnical conclusions and recommendations for the design of the new water storage tank. The location of the project site is shown on Plate 1 Site Location Map. This report includes geotechnical engineering conclusions and recommendations related to subsurface conditions, geoseismic hazards, geotechnical design considerations, site improvements, earthwork, and construction monitoring for the proposed project. The conclusions and recommendations presented in this report are based on the subsurface conditions encountered at the location of one boring drilled for this study, available geotechnical information from other studies in the vicinity of the project site, and available geologic information for the area. The conclusions and recommendations presented in this report should not be extrapolated to other areas or used for other facilities without prior review by AGS. 1.2 PROJECT DESCRIPTION AGS understands that the proposed project includes construction of a new steel water storage tank, a 5000-gallon horizontal hydropneumatic tank, two new pipelines, and associated structures such as booster pump station, valves and bends. The proposed water storage tank will be about 46 feet in diameter and 24 feet in height. The dead load (including the weight of full water and concrete foundation) and live load are estimated to be 3,300 kips and 250 kips, respectively. The total based shear force is estimated to be between 400 kips to 800 kips. Walnut Grove Water System 1 November 2012

8 AGS understand that two pipes will be constructed. One pipe will be approximately 400 lineal feet gravity sewer pipe and the other will be an approximately 1,100 lineal feet 6-inch pressurized water pipe. The sewer pipe will be constructed between the existing Arsenic Removal Water Treatment Plant (ARWTP) and the Islandview Way, and the pressurized pipe will be constructed between ARWTP and the proposed steel tank. Based on profile map of 6-inch pipeline (entitled as Preliminary Design Phase June 2012, Sheet C-06), the alignment of the proposed pipeline extends along 1 st Street, Island Way and the dirt access road, and will be located about 4 to 6 feet below the existing ground surface. The alignment of the pressurized water pipeline crosses at least four 6- to 15-inch diameter utility lines which located at about 6- to 12-inch above or below the proposed pipeline. The alignment of the sewer pipeline is not available at the time of this study. 1.3 WORK PERFORMED As stated in the revised proposal, dated May 18, 2012, the purpose of the study was to explore and evaluate subsurface conditions and develop final site-specific geotechnical conclusions and recommendations for design of the proposed tank. The work performed for this geotechnical study included the following tasks Review of Available Data AGS reviewed readily available reports of geotechnical studies previously conducted by others including a geotechnical study performed by Youngdahl Consulting Group, Inc. (YCI) at the location of the ARWTP in 2006, and available published geotechnical, geologic, and seismologic data of the vicinity of the project site Field Exploration AGS conducted a field exploration program consisting of drilling one boring. Boring B-1 was extended to a depth of approximately 94 feet below the existing ground surface. The field exploration program was performed on July 26, Walnut Grove Water System 2 November 2012

9 AGS notified Underground Service Alert a minimum of 48-hours in advance of any invasive work and renewed the notifications as required. AGS scheduled and coordinated access to the test location with WGWS personnel. AGS obtained a permit from Sacramento County, Environmental Management Department. The field exploration program was performed under the technical supervision of a qualified geologist from AGS who has extensive experience on the soil conditions in the area. A log of boring and the conditions encountered at the site were recorded by the geologist in the field. The boring was backfilled with cement grout and the ground surface at the location of the boring was restored to the original condition. The drill cuttings generated from the drilling operation were placed into a 55-gallon drum, which was labeled, and left at the site. The location of the boring drilled for this study is shown on Plate 2 Boring Location Map. Details of the field exploration program, including copy of the boring log, are included in Appendix A - Field Exploration and Sampling Geotechnical Laboratory Testing Laboratory tests were performed on selected soil samples obtained during the field exploration program. The laboratory tests included moisture, density, sieve analyses, Atterberg limits, consolidation, and unconfined compressive strength testing of the earth materials. Details of the geotechnical laboratory testing program are included in Appendix B - Geotechnical Field and Laboratory Testing. Samples were submitted to an outside laboratory for corrosivity testing, and the results are included in Appendix C Corrosivity Testing. Walnut Grove Water System 3 November 2012

10 1.3.4 Engineering Analyses and Report Preparation The data generated were used to perform engineering analyses in order to develop sitespecific geotechnical conclusions and recommendations for the design and construction of the proposed project. Our geotechnical findings, conclusions, and recommendations, along with the supporting data, are presented in this engineering report. The report addresses the following: Subsurface soil conditions; Local geologic conditions; Groundwater elevations; Faults and seismicity; Probabilistic seismic hazards evaluation; 2010 CBC Seismic Design Criteria; Geoseismic hazards including liquefaction potential, seismically-induced settlements, and seismically-induced lateral deformation; Total and differential settlement, and time rate of settlement; Settlement mitigation measures; Liquefaction potential, consequences, and mitigation measure; Earthwork and subgrade preparation recommendations; Shallow/mat foundation design recommendations; Deep foundation design recommendations; Resistance of shallow/mat and deep foundations to lateral loads; Pipeline design parameters; Soil corrosivity; Effects of the construction on the adjacent structures; and Construction considerations. Walnut Grove Water System 4 November 2012

11 2.0 FINDINGS 2.1 SITE CONDITIONS The proposed project area is farmland, located approximately 2,000 feet from the western bank of the Sacramento River. It is surrounded by farms to the north, to the west and to the south, and by an existing water treatment facility plant to the east. The existing plant to the east side of the project site is about 60 feet by 80 feet in plan view. The project site is relatively flat with an elevation about -3 feet (NGVD29). An old pavement driveway connects the site and adjacent facility plant to Islandview Way. 2.2 GEOLOGY The project site is located within the Great Valley geomorphic province of California which is underlain by Cretaceous, Tertiary and Quaternary age sediments. This province may exceed about 4,500 feet in thickness in the Solano County area. According to the 1:250,000 scale Sacramento Quadrangle of California State Geology map, the project site is underlain by Quaternary-Age intertidal deposits of peaty mud. 2.3 FAULTS AND SEISMICITY The project area is located in a seismically active region which has been subjected to several strong earthquakes during historic time. The closest fault to the site is the Great Valley 3 Fault, which appears 29 kilometers (km) to the east of the site. Further from the project site are the Bartlett Spring-Fault System and the San Andreas Fault, which pass at about 61 km and 82 km from the site, respectively. The maximum moment magnitude earthquake (Mmax) is defined as the largest earthquake that a given fault is considered capable of generating. The seismicity Walnut Grove Water System 5 November 2012

12 associated with each pertinent fault, including estimated slip rates, is summarized below in Table 1 - Fault Seismicity. TABLE 1 FAULT SEISMICITY Distance to Site 1 (km) Maximum Moment Magnitude 2 Slip Rate 2 (mm/year) Fault Great Valley Bartlett Spring San Andreas Jennings (1994) 2. Working Group 02 (2003) There are other active faults in the region, but these are either farther from the project site or smaller and, therefore, would not be capable of causing shaking at the project site as strong as those caused by the faults listed in Table SUBSURFACE CONDITIONS AGS performed this geotechnical study to explore and evaluate subsurface conditions and develop geotechnical engineering recommendations for design of the proposed water storage tank. The field exploration program consisted of drilling one boring at the site. The subsurface conditions encountered in Boring B-1 consisted of approximately 7 feet of very soft organic silt and clay (peat) materials is underlain with approximately 5 feet of very soft sandy silt materials. The sandy silt material is underlain with approximately 18 feet of very loose to loose silty sand layers. The loose sandy material is underlain with approximately 23 feet of medium stiff sand with silt layers. Under medium stiff sand layers, approximately 41 feet of stiff to hard fat clay and sandy clay materials were encountered to the maximum explored depth of approximately 94 feet below the existing ground surface. Walnut Grove Water System 6 November 2012

13 2.5 SOIL CORROSIVITY Samples of soil were taken from Boring B-1 at respective depths of 0.0 to 0.5 feet and 1.0 to 3.0 feet for corrosion testing. Samples were tested for resistivity at 100-percent saturation (ASTM G57), chloride content (ASTM D4327/ Cal 422-mod.), sulfate content (ASTM D4327/ Cal 417-mod.), ph (ASTM G51), and redox potential (SM 2580B), to evaluate potential soil corrosivity to buried metal and concrete. AGS conclusions about the corrosion potential of subsurface materials are presented in Section 3.8. The results of the corrosivity tests are provided in Appendix C. 2.6 GROUNDWATER Groundwater was measured in Boring B-1 at approximately 3 feet below the existing ground surface. The elevation of the site is about -3 feet (NGVD29). Based on the result of current study and previous geotechnical reports in vicinity of the site, a groundwater level at ground surface elevation can be used for design purposes. Variations in the groundwater level at the site are likely to occur due to influences from fluctuations in the nearby river, changes in precipitation and temperature, and other factors not evident at the time of this study. 2.7 FLOOD INSURANCE RATE MAP The project site is located about 2,000 feet west of the Sacramento River. According to FIRM Map Number 06067C0560H, the proposed project site is located in Zone AE, part of the Special Flood Hazard Areas. The base flood elevation is about 16 feet (North America Vertical Datum of 1988). The 1% annual flood (100-years flood), also known as the base flood, is the flood that has a 1% chance of being equal or exceeded in any given year. The base flood elevation is the water-surface elevation of the 1% annual chance flood. Walnut Grove Water System 7 November 2012

14 3.0 CONCLUSIONS AND RECOMMENDATIONS 3.1 GENERAL Based on the results of the field exploration and geotechnical laboratory testing programs, it is the opinion of AGS that it is geotechnically feasible to construct the proposed water storage tank and associated pipelines provided the recommendations presented in this report are incorporated into the design and construction of the project. The major geotechnical considerations for this project are: Presence of compressible soils with the potential of up to 10 inches of static settlement; The potential for liquefaction and seismically-induced settlements up to about 9 inches; and The impact of the groundwater during construction. 3.2 SEISMIC DESIGN CONSIDERATIONS General The geotechnical seismic design recommendations and geoseismic hazards are summarized below and were developed considering the subsurface conditions encountered during this study and the seismic sources as indicated in Section 2.3, Table 1, of this report Fault Rapture Hazard The site is not within any Alquist-Priolo Special Studies zones, and there is no evidence that the project site is located on an active fault. Therefore, damage due to fault rupture at the site is considered unlikely. Walnut Grove Water System 8 November 2012

15 3.2.3 Maximum Earthquake The Mmax earthquake is the largest earthquake that a given fault appears capable of generating. The controlling Mmax earthquake for the project site would be a magnitude 6.9 event occurring along the Great Valley 3 Fault at a distance of approximately 29 km from the site. A Mmax earthquake would have strong shaking for a duration of approximately 15 to 30 seconds with a predominant period of approximately 0.25 seconds at bedrock Estimated Earthquake Ground Motions Ground surface accelerations were estimated using both deterministic methods and probabilistic methods, using the EZ-FRISK computer software package Version These acceleration values were developed in the cases of 5.0 percent and 0.5 percent damping Deterministic Methods Correlations between distance from a causative fault and mean values of the peak bedrock accelerations and the effects of local soil conditions on peak ground accelerations have been developed for very dense soil and soft rock site through various attenuation relationships. Recent seismic models use the so-called next generation attenuation (NGA) relationships. These NGA relationships were used to calculate seismic acceleration values at the project site. In particular, the relationships by Abrahamson and Silva (2008), Boore and Atkinson (2008), Campbell and Bozorgnia (2008), and Chiou and Youngs (2008) were used to calculate the peak ground accelerations at the project site. Based on average values of the peak ground acceleration calculated by these four correlations, a Maximum Moment Magnitude (Mmax) of 6.9 occurring of the Great Valley 3 Fault, located approximately 29 km away, the peak horizontal ground surface acceleration (PGA) is estimated to be 0.15 g at the site for mean peak horizontal ground Walnut Grove Water System 9 November 2012

16 acceleration. Lesser values of PGA may be used for design depending on the level of risk acceptable to the designer Probabilistic Methods For the project site, peak horizontal ground accelerations were developed in accordance with 2010 CBC/ASCE 7-05 Section 21.3 for the average earthquake return period of 2,500 years, using the NGA relationships developed by Abrahamson and Silva (2008), Boore and Atkinson (2008), Campbell and Bozorgnia (2008), and Chiou and Youngs (2008). This earthquake return period corresponds to an approximately 2 percent probability of being exceeded in 50 years. The estimated average value of peak horizontal acceleration calculated from the four attenuation relationships discussed above is 0.32g CBC Seismic Design Criteria Based on the explored subsurface conditions and the seismic criteria, design seismic parameters were determined using the 2010 California building Code (CBC), AWWA D100-11, and ASCE 7-05 procedures as described in Table 2 below. TABLE 2 SEISMIC CRITERIA Factor Site Class/ Value Site Class Short-Period (0.2 sec.) MCE, g MCE* at 1 sec., g F Ss 0.85 S Walnut Grove Water System 10 November 2012

17 3.2.8 Design Earthquake The project site is classified as Site Class F. According to AWWA D100-11, Section Design Response Spectra -Required Site-Specific, the design response spectrum for impulsive components in a site classified as Site Class F, should be based on 2,500-year return period, corresponding to 5 percent damping. Based on the results of the probabilistic seismic hazard evaluation 2,500-year return period earthquake is estimated to have peak horizontal ground surface accelerations (PGA) of 0.32g. The probabilistic spectral response acceleration of 2,500-year return period, corresponding to 5 and 0.5 percent structural damping ratios (ASCE 7-5, Section ), as well as the deterministic response acceleration (ASCE 7-5, Section ), and the design spectral response acceleration in accordance with Sections 21.3 and 21.4 of ASCE 7-5, are presented on Table Vertical Acceleration AGS recommends that the peak vertical component of the acceleration be taken as equal to ¾ of the peak horizontal acceleration component discussed above Liquefaction Hazard Soil liquefaction is a phenomenon in which saturated (submerged) cohesionless soils lose their strength due to the build-up of excess pore water pressure, especially during cyclic loadings such as those induced by earthquakes. In the process, the soil acquires mobility sufficient to permit both horizontal and vertical movements, if not confined. Soils most susceptible to liquefaction are loose, clean, uniformly graded, fine-grained sands. Silty and clayey sands may also liquefy during strong ground shaking. Walnut Grove Water System 11 November 2012

18 TABLE 3 SPECTRAL ACCELERATIONS Spectral Acceleration Value Probabilistic Analysis Deterministic Period 2,500-Year Return Period Analysis 2010 CBC Design Values (sec) (ASCE 7-5, Section ) (ASCE 7-5, Section ) (ASCE 7-5, Sections 21.3 and 21.4) 5% Damping 0.5% Damping Mean 5% Damping 0.5% Damping (g) (g) (g) (g) (g) PGA Walnut Grove Water System 12 November 2012

19 The nature of liquefaction depends greatly on the characteristics of the soil. In loose soils, liquefaction results in significant loss of soil strength, which can lead to large deformations. In dense soils, although a condition of liquefaction can be initiated, the tendencies for loss of strength and deformations are resisted by dilation of the soils. Deformations in dense soils result in a tendency for soil volume increase (dilation), which in turn results in reduction of pore water pressures, increase in effective stresses, and increased resistance to further deformations. The liquefaction potential of soils at the project site was evaluated using a simplified, analytical, and empirical procedure that is correlated with the liquefaction behavior of saturated sands during historic earthquakes (Youd, 2001; and Idriss and Boullanger, 2008). The primary data utilized in the analysis consisted of standard penetration test (SPT) and modified California (MC) sampler blow counts, which were obtained from the one boring drilled at the site. The SPT and MC blow counts recorded in the field were corrected for various factors to obtain corrected N-values, which were used in the liquefaction analysis. The factors used to obtain corrected N-values, included the effects of overburden pressure, rod length, sampler type and size, and fines content. During drilling, the groundwater was measured at depths of approximately 3 feet below the existing ground surface in Borings B-1. A design groundwater at existing ground surface was assumed because of the likelihood of the water level fluctuation in future, and the elevation of the existing site (-3 feet). The liquefaction analysis was conducted using the following parameters. Magnitude 6.9 earthquake Peak horizontal acceleration of 0.21g Groundwater depth at the existing ground surface Based on the results of the liquefaction analysis, the very loose to medium dense granular materials (7 to 35 feet below existing ground surface) at the project site are considered to have a high liquefaction potential. Plate D-1 in Appendix D shows the liquefiable layer(s) at the location of Boring B-1. Walnut Grove Water System 13 November 2012

20 Consequences of Liquefaction The main effects of liquefaction at the project site include settlement of the ground surface and utilities, lateral deformation, development of excess pore water pressure, buoyancy effects on the below groundwater structures, loss of allowable bearing pressure, and increased lateral pressures on utilities and foundations extending below the groundwater table Seismically-Induced Settlements The results of the liquefaction analysis conducted for Boring B-1 is included in Appendix D. The estimated seismically-induced settlement is up to approximately 9 inches based on subsurface exploration results obtained at location of Borings B-1. It is the opinion of AGS that differential seismically-induced settlement along 100 feet of length within the project site is less than half of the above-mentioned seismically-induced settlement. If the anticipated seismically-induced settlement is not acceptable to the designer, AGS recommends that a soil improvement program as discussed in Section 3.5.2, be used to reduce liquefaction consequences to an acceptable level. However, AGS understands that it would not be economically feasible to construct ground improvements to reduce liquefaction effects in project site, and even with soil improvements the proposed structures could be damaged during a magnitude 6.9 or greater earthquake. Another option to reduce the liquefaction impact on the proposed structures is to support the proposed structures on deep foundation system Lateral Deformation Seismically-induced lateral deformation is another phenomenon which can occur during a seismic event. The continuity/discontinuity of potentially liquefiable soil layers is a key Walnut Grove Water System 14 November 2012

21 consideration in evaluating the potential for lateral deformation. During Lateral spread, blocks of mostly intact, surficial soil displace downslope or towards a free face along a shear zone that has formed within the liquefied sediment. The project site is located about 2,000 feet from the Sacramento River. It is unlikely that lateral spread extends within 2,000 feet towards the river bank. In general, due to lack of slope at site and large distance between the site and river bank, the potential of liquefaction lateral spreading at project site is low Liquefaction Mitigation The project site is underlain by potentially liquefiable soils. Some settlements and cracking may result from differential seismically-induced settlements of liquefiable soils during an earthquake and could damage the proposed structures. A seismically-induced settlement of up to 9 inches within the project site is anticipated, as discussed previously. A mitigation plan should be employed where estimated seismically-induced settlements cannot be tolerated. Ground improvement can be performed in areas where the total calculated seismicallyinduced settlement exceeds the structurally acceptable level, and be designed to reduce the total liquefaction-induced deformation to a tolerable level. Based on the AGS s boring, the soil zone to be improved includes those soils which are at depth of 5 to 30 feet. If the soils which are at the depth of 5 to 30 feet are improved, seismicallyinduced settlement will reduce to about 1 inch with differential seismically-induced settlement of 0.5 inch along 100 lineal feet. The total thickness of the zone to be improved depends both on the actual thickness of the potentially liquefiable material and the desired reduction in predicted settlement. The details of soil improvements are discussed in Section Alternatively, the existing structures may be supported on deep foundations incorporating impact of liquefaction-induced earth and pore-water pressures in design of Walnut Grove Water System 15 November 2012

22 the new deep foundation system. More details and foundation options are discussed in Section EXCAVATION AND EARTHWORK Site Preparation Prior to the site grading all existing structures should be removed and debris should be properly disposed of outside the construction area. Existing above and underground utilities located within the proposed construction areas, if affected by construction activities, should be relocated prior to excavation. Debris generated from the demolition of underground utilities, including abandoned pipes, should be removed from the site as construction proceeds Overexcavation If deep foundation system is not chosen for the proposed 5000-gallon horizontal hydropneumatic tank, the existing soils below the tank footprint area extending to a depth of 7 feet should be overexcavated and replaced with structural fill. In the proposed paved area around the new steel water storage tank, the soils should also be overexcavated and replaced with structural fill extending to a depth of 3 feet below ground surface. Upon completion of excavation, backfill may be placed in accordance with the recommendations presented in the following sections. The overexcavated sandy and clayey soils may be reused as structural fill provided that they meet the criteria described in Section The materials within 6 feet of ground surface encountered in Boring B-1 were organic silt which does not meet the criteria described in Section The excavated soils which do not meet the above-mentioned requirements may be mixed with import soil to achieve the required gradation and plasticity limit. Fill and backfill materials should be observed and tested by the geotechnical engineer prior to their use in order to evaluate their suitability. Walnut Grove Water System 16 November 2012

23 3.3.3 Fills and Backfills Fills and backfills may either be structural or nonstructural. Structural fills and backfills are defined as providing support to foundations, slabs, and pavements. Nonstructural fills and backfills include all other fills such as those placed for landscaping, and not planned for future structural loads. Structural fills and backfills should be compacted to at least 95 percent of the maximum dry density per ASTM D-1557; nonstructural fills and backfills should be compacted to at least 90 percent of the maximum dry density as determined per ASTM D If the proposed water tank is to be founded on shallow foundations, in addition to soil improvement, the top 5 feet of the subsurface materials at the project site should be removed and replaced with structural fill. If the proposed water tank will be supported on deep foundations, structural fill is not required. Structural fill and backfill materials should be placed in lifts not exceeding approximately 8 inches in loose thickness, brought to near-optimum moisture content and compacted using mechanical compaction equipment. Nonstructural fills and backfills may be placed in lifts not exceeding 12 inches in loose thickness and compacted in a similar manner. No grading information was available at the time of this report. It is anticipated that the backfilling necessary at the completion of the debris removal will be achieved using the import material. In case that import fill is required to achieve the design grades, it should be placed and compacted under the full time inspection and testing of the project geotechnical engineering firm. Material to be used as compacted fill and backfill should be predominantly granular, less than 3 inches in any dimension, free of organic and inorganic debris, and contain less than 20 percent of mostly non-plastic fines passing the No. 200 sieve. The fill and backfill soils should have a liquid limit less than 35 and plasticity index less than 12. Samples of fill and backfill materials should be submitted Walnut Grove Water System 17 November 2012

24 to the geotechnical engineer prior to use for testing to establish that they meet the above criteria Temporary Excavations Significant mass excavation of soil is not anticipated for this project. However, some excavation of soil will be necessary in conjunction with removal of in-fill material within the slipway. In case of massive excavation, excavations must comply with the current requirements of OSHA or Cal-OSHA, as applicable. Additionally, all cuts deeper than 5 feet should be sloped or shored. Shallow excavations above the groundwater level may be sloped if space permits. It is our opinion that temporary excavations may be sloped at 1½H:1V (Horizontal to Vertical) above and below the groundwater level, respectively. The groundwater is estimated to be as shallow as 1 to 2 feet below the existing ground surface; however, it is the responsibility of the contractor to maintain safe and stable slopes or design and provide shoring during construction. Flatter slopes will be required if clean or loose sandy soils are encountered along the slope face. Heavy construction equipment, building materials, excavated soil, and vehicle traffic should not be allowed within 7 feet of the top of excavations Dewatering If the existing subsurface materials are removed, groundwater may be encountered during excavation. The contractor should be responsible for selecting the appropriate range of groundwater levels for dewatering design, and for providing an adequate dewatering system during construction. A properly designed, installed, and operated dewatering system should: Lower the water table inside the excavation or intercept any seepage which will emerge from the sides or the bottom of the excavation; Walnut Grove Water System 18 November 2012

25 Improve the stability of the excavation and prevent disturbance of the bottom of the excavation; Provide a reasonably dry working area in the bottom of the excavation; and, Provide for collection and removal of surface water and rainfall. It is recommended that the water level be maintained at least two feet below the bottom of the excavation until the proposed structure is constructed, and the weight of the structure and the hold-down system are sufficient to resist buoyancy. Selection of the equipment and methods of dewatering should be left up to the contractor, who should be aware that modifications to the dewatering system may be required during construction, depending on conditions encountered. Water collected during dewatering should be tested for contamination prior to disposal. It is the responsibility of the contractor to properly contain and dispose of the discharged water. 3.4 PIPELINES General The proposed water pipeline will be constructed at 4 to 5 feet below the existing ground surface. Based on log of Boring B-1, the top 7 feet of subsurface materials are mainly very soft to soft organic clay and silt. Based on our evaluations of subsurface conditions, it is our opinion that the subsurface materials at the site will provide adequate support to the pipelines. Shoring trench and dewatering might be necessary in some areas Earth Loads Earth loads on pipelines due to the overlying soil will be dependent upon the depth of placement, width of the trench at the top of the pipe, the backfill type and placement, and the Walnut Grove Water System 19 November 2012

26 type of pipe. It is likely that the pipelines will be placed in trenches with near-vertical sides. The earth load on the pipelines should be calculated using formulas developed by Marston (1930). For the proposed pipelines constructed in a "trench" condition, AGS recommends that equations 1 and 2 be used for rigid and flexible pipes, respectively. W c = C d W (B d ) 2 (1) W c = C d W B d B c (2) Where: W c = Vertical load on the pipe in pounds per unit length C d = An empirical coefficient described by Marston (1930) W = Unit weight of the trench backfill material in pcf B d = Width of the trench at the top of the pipe in feet B c = Outside diameter of the pipe in feet When using the above equations, the empirical coefficient, C d, can be obtained from Plate 3 - Earth Load Coefficients for Pipeline Design. The data presented on Plate 3 are developed for saturated soils. AGS recommends using the data for saturated soils in order to avoid damage to pipelines resulting from possible saturation of subsurface soils. The unit weight of the trench backfill, W, can be assumed as 130 pcf. It is estimated that most of the pipes will be placed in the "trench" condition. However, if the width of the trench is greater than two times the diameter of the pipe, the earth loads on the pipe may be larger than those calculated by equations 1 and 2. The earth loads should then be calculated on the basis of Marston's formula for "embankment" conditions (Marston, 1930) and the prism load should be used for flexible pipes Surcharge Pressures For any surcharge applied on the pipelines, the vertical pressures on the pipelines may be estimated using the pressure diagrams presented on Plate 4 - Vertical Surcharge Pressures. The horizontal surcharge pressures may be estimated using Plates 5 and 6. Walnut Grove Water System 20 November 2012

27 3.4.4 Modulus of Earth Reaction A modulus of earth reaction of 150 psi due to very soft to soft clay can be used to estimate deformation of the proposed pipelines along the project alignment. This recommended modulus of earth reaction is estimated based on the earth materials encountered in the borings drilled for this study along the proposed pipelines alignment Thrust Resistance Where the proposed pipelines change direction abruptly, resistance to thrust forces can be provided by mobilizing frictional resistance between the pipe circumference and surrounding earth material, by the use of a thrust block, or by a combination of the two. The frictional resistance can be calculated utilizing coefficients of friction of 0.35 between polyethylene coated pipe and adjacent backfill; and 0.40 between cement mortar armor coated pipe and adjacent backfill. Pipe segments may be connected by tension joints capable of transmitting the required thrust forces if more than one segment of pipe is needed. Passive resistance at a thrust block may be used instead of, or in conjunction with, frictional resistance to resist pipe thrust. Based on the earth materials encountered in the boring drilled for this study, equivalent fluid pressures of 250 and 120 pcf should be used for design above and below the groundwater level, respectively, for thrust blocks that are used in backfill materials Trench Width Minimum trench widths should be provided in order to ensure uniform support for the pipelines. AGS recommends that the trench be a minimum of two feet wider than the outside diameter of the pipe at each side of the pipe. The minimum clear width of trench at the top of the pipe is recommended to be not more than the outside diameter of the pipe plus four feet. Walnut Grove Water System 21 November 2012

28 3.4.7 Pipe Bedding The proposed pipelines should be completely surrounded with bedding material to provide uniform support and protection. The bedding should consist of medium to coarse-grained sand, or crushed rock of less than ¾ inch in maximum size. The material should be of uniform gradation. Pipe bedding should be placed beneath the pipe with a minimum thickness of 9 inches, and should extend 12 inches above the spring line of the pipes. All bedding material should be placed carefully to achieve uniform contact with the pipe and a minimum relative compaction of 90 percent as determined by standard test method ASTM D1557. Compaction by jetting or flooding should not be permitted Trench Backfill Trench backfill materials within pipe zone (extending from the trench bottom to a minimum of 9 inches above the pipe) should conform to the requirements of fill and backfill materials presented in Section Trench backfill should be compacted in layers not exceeding eight inches in uncompacted thickness and should be compacted to 90 percent relative compaction as determined by ASTM D1557, except for trenches under pavements or slabs. The material used for pipe bedding (the area from bottom of the pipe to 9 inches below the pipe) and the pipe zone should be the same and receive the same compaction effort. Under the pavement or slab areas, the upper 3 feet of the backfill measured from the top of the pavements or slab should conform to the requirements of the individual agency encroachment permits ( County, Caltrans, etc.). The pipe bedding materials should also be compacted to 95 percent relative compaction as determined by ASTM D1557. Walnut Grove Water System 22 November 2012

29 3.5 FOUNDATIONS General AGS recommends that if the seismically-induced and static settlements cannot be tolerated by the proposed structures, either soil improvement should be performed and the top 5 feet of the subsurface materials be overexcavated and replaced with structural fill, or the proposed structures should be founded on deep foundations. Due to seismically-induced and static differential settlement, and loss of allowable bearing pressure, AGS does not recommend that the proposed structures be supported on shallow or mat foundation system without any soil improvement and placement of structural fill. If the proposed 5000-gallon horizontal hydropneumatic tank will be supported on the mat foundation system without any soil improvement, it is recommended that the upper 7 feet be removed and replaced with structural fill in accordance with Section of this report. Dewatering may be required during excavation and backfilling. It is recommended that a coefficient of subgrade reaction of 20 pounds per cubic inch be used for design of the mat foundations. This value of subgrade reaction is based on immediate, elastic settlement estimates. An allowable bearing pressure of 600 pounds per square foot (psf) may be used for mat foundations. The allowable bearing pressure is not a net value. Therefore, the weight of the foundation should be considered when computing dead loads. The bearing pressure applies to dead plus sustained live load and includes a calculated factor of safety of about 3. The allowable pressure may be increased by one-third for short-term loading due to wind or seismic forces. If the static and seismically-induced settlements cannot be tolerated, the proposed 5000-gallon horizontal hydropneumatic tank may be supported in accordance with the recommendations mentioned in Section after implementation of soil improvement or Section without any soil improvement. Walnut Grove Water System 23 November 2012

30 3.5.2 Soil Improvement This section provides options for mitigation of seismic-induced settlements through a program of soil improvement. Due to the presence of very loose to loose sandy layers within the subsurface materials, caving is anticipated during drilling. Contractor should be familiar with techniques such as mud pressure or casing to prevent the caving. Some available techniques for soil improvement which may be applicable to this site include: vibro-replacement stone columns, grouting techniques, and dynamic deep compaction. Vibro-Replacement Stone Columns The vibro-replacement stone column technique of ground treatment, in which a vibrator penetrates to depth by means of its weight and vibrations and horizontal vibrations are generated at treatment depth by the use of eccentric weights that are rotated by means of electric motors, has proven successful in reducing the liquefaction potential of sands and low plasticity silt. Stone columns are used for loose silty sands having greater than about 15 percent fines. Cohesive, mixed and layered soils generally do not densify easily when subjected to vibration alone, therefore, the vibro-replacement stone column technique was developed specifically for these soils, effectively extending the range of soil types that can be improved with the deep vibratory process. Grouting Grouting techniques (compaction, permeation, deep mixing, chemical, and jet grouting) of soil improvement have also proven successful in reducing the liquefaction potential of sandy material. The grouting techniques become less efficient with increased fine content, such as silt and clay. Of these grouting techniques, jet grouting appears to be the most efficient method for the site. Essentially, in jet grouting, ultra high pressure fluids or binders are injected into the soil at a high velocity. These binders break up the soil structure completely and mix the soil particles in-situ to create a homogeneous mass which in turn solidifies. Other grouting techniques, such as deep mixing, involve Walnut Grove Water System 24 November 2012

31 the use of large augers both to introduce cement grout and to mix it with the soil, producing a treated soil cement column. Dynamic Deep Compaction Dynamic deep compaction can densify and reduce the liquefaction potential of sandy soils. This method becomes less effective with high groundwater level and increased fine content in soils, but has relatively lower cost compared to other methods. However, due to the effects of vibrations on the adjacent properties, AGS believes that this method is not applicable for this site. The soil improvement design, if chosen as an economically feasible, will depend on the costs of performing the work as well as the technical specifics of the work, and is beyond the scope of this study. The practical applications of many of these measures have been presented in the literature (Hryciw 1995; Stewart et al. 1997; Boulanger et al. 1997; Mitchell et al. 1998b) and summarized in Table Shallow Foundations Provided the subsurface sandy soils are improved using a soil improvement technique, the proposed water tank can be founded on shallow foundations. The existing upper soils extending to a deep of 5 feet should be overexcavated and replaced with structural fill. It is AGS opinion that the proposed water tank can be supported on shallow foundation system, constructed on a minimum of 2 feet of structural fill materials. Ring Footings Ring foundations should extend at least 24 inches below the lowest adjacent finished grade and be at least 24 inches wide. An allowable bearing pressure of 2,500 pounds per square foot (psf) may be used for ring footings. The allowable bearing pressure is a net value. Therefore, the weight of the foundation and the backfill over the foundation Walnut Grove Water System 25 November 2012

32 may be neglected when computing dead loads. The bearing pressure applies to dead plus sustained live load and includes a calculated factor of safety of about 3. The allowable pressure may be increased by one-third for short-term loading due to wind or seismic forces. TABLE 4 SUMMARY OF LIQUEFACTION MITIGATION TECHNIQUES Liquefaction Mitigation Technique Vibro-Replacement Stone Column Grouting compaction grouting deep mixing grouting permeation grouting chemical grouting jet grouting Advantages Disadvantages Relative Cost Effective and economical method in many situations. Able to reach depths unattainable by other methods. Pinpoint treatment, Speed of installation, Wide applications range. Can be performed in very tight access and low headroom conditions, Non-hazardous, no waste spoil disposal. Able to reach depths unattainable by other methods. Wide applications range (even with high fine contents), Cost savings over deep foundation designs. Installation methods are customized for the site conditions. Minimum disturbance of the native soil. Can be performed in very tight access and low headroom conditions. Pinpoint treatment. Minimum disturbance of the native soil. Can be performed in very tight access and low headroom conditions. Pinpoint treatment. Nearly all soil types groutable. Most effective method of direct underpinning of structures and utilities. Safest method of underpinning construction. Ability to work around buried active utilities, can be performed in limited workspace, treatment to specific subsurface locations, no harmful vibrations. Much faster than alternative methods. Ineffective for densifying soils with greater than 20% fine contents. The liquefiable soil should have a minimum thickness for this method to be effective. Waste spoils disposal is required. Not effective at depths with low confining pressure (<15 feet). Ground surface heave due to grout pressure. Very low reinforcing effects of the compaction grout bulbs/columns. Waste spoils disposal is required. Significant overhead clearance is required. Pinpoint treatment is not applicable. Very low reinforcing effects of the compaction grout columns. Construction process is complex. Very costly. limited to clean sands and ineffective in soils with fines. Construction process is complex. Very costly. limited to clean sands and ineffective in soils with fines. Soil erodibility plays a major role in predicting geometry, quality and production. Cohesionless soils are typically more erodible than cohesive soils. Pinpoint treatment is not applicable. Very low reinforcing effects of the compaction grout bulbs/columns. Moderate Low to moderate High High High High Walnut Grove Water System 26 November 2012

33 Mat Foundations For the proposed steel water storage tank, it is recommended that a coefficient of subgrade reaction of 60 pounds per cubic inch be used for design of the mat foundations. This value of subgrade reaction is based on immediate, elastic settlement estimates. An allowable bearing pressure of 1,500 pounds per square foot (psf) may be used for mat foundations. The allowable bearing pressure is a net value. Therefore, the weight of the foundation may be neglected when computing dead loads. The bearing pressure applies to dead plus sustained live load and includes a calculated factor of safety of about 3. The allowable pressure may be increased by one-third for short-term loading due to wind or seismic forces Deep Foundation System We understand that 14-inch square reinforced concrete piles are considered to be used to support the proposed water tank. AGS evaluated the lateral and axial capacities of the proposed piles based on boring data and the information provided by Structural Engineer. AGS recommends adding pre-cast concrete driven piles. Lateral and axial capacities of proposed pre-cast concrete driven piles with 14-inch square were evaluated in this report. AGS estimated the allowable compression and uplift capacities of 14-inch square reinforced concrete driven piles, for different depth of piles, and presented in Table 5. The driven piles should be at least 70 feet long to develop their capacity from the friction in the clay and sandy soil materials. Walnut Grove Water System 27 November 2012

34 TABLE 5 ESTIMATE ALLOWABLE COMPRESSION AND UPLIFT CAPACITIES OF 14-INCH SQUARE DRIVEN PILES Depth of Piles (feet) Compression Capacity (kips) Uplift Capacity (kips) Effect of liquefaction and downdrag are incorporated in the vertical capacity. A downdrag force of 40 kips is estimated for each pile. The driven piles capacities include a factor of safety of two or greater. The recommended allowable uplift capacity does not include the effect of the weight of piles. The buoyant weight of the piles should be added to the recommended uplift capacity to estimate total allowable uplift capacity. The uplift is based on the resistance capacities of the soils; the structural tension capacity of the piles should be checked by the project structural engineer. The effect of vibration on adjacent structures, during the construction of driven pile, should be analyzed. If the vibrations due to construction of driven piles are not tolerated with adjacent structures, vibration-free pile should be used General Deep Foundation Recommendation The structural capacities of the driven piles depend on the strength of the materials used, which should be checked by the project structural engineer. Spacing should be determined as required by the load distribution, but minimum spacing should not be less than 3 pile diameters, center to center. Maximum spacing is to be determined by the Structural Engineer. To resist lateral loads, the passive Walnut Grove Water System 28 November 2012

35 resistance of the soil can be used. The soil passive pressures can be assumed to act against the lateral projected area of the pile described by the vertical dimension of twice the pile diameter. The allowable pile capacity should be reduced by group action when spaced closer than three times the width, and where this occurs additional geotechnical analyses will be necessary. 3.6 RESISTANCE TO LATERAL LOADS Shallow / Mat Foundations Resistance to lateral loads for shallow and mat foundations may be provided by frictional resistance between the bottom of spread footings and the underlying earth materials, and by passive pressure of the earth materials against the sides of the shallow and mat foundations. The coefficient of friction between poured-in-place concrete foundations and the underlying earth materials may be taken as Passive pressure available in compacted backfill or undisturbed earth materials may be taken as equivalent to the pressure exerted by a fluid weighing 250 pcf. The above-recommended value includes a calculated factor of safety of at least 1.5; therefore, frictional and passive pressure resistance may be used in combination without reduction Deep Foundations Resistance to lateral loads on driven pile is provided by passive earth pressure against the pile and by the bending strength of the pile foundations itself. Plate 7 - Response to Lateral Loading, show estimated lateral capacities as functions of lateral deformation, and maximum induced shear forces and bending moments for 14-inch square driven piles with fixed head. The given lateral capacities and moments depend on the allowable deflection at the top of the piles as shown on Plate 7. Walnut Grove Water System 29 November 2012

36 The maximum shear forces on driven pile corresponding to ¼-inch lateral deflection at top of piles is about 6 kips. Additional resistance to lateral loads on pile cap structure may be provided by frictional resistance between the bottom of pile cap and the underlying earth materials, and by passive pressure of the earth materials against the sides of the pile cap using the geotechnical parameters presented in Section SETTLEMENT Static Settlements Improved Soil If the proposed water tank is to be founded on shallow foundations constructed on a minimum of two feet of fill structure underlain by improved soil, as was explained in Section 3.5.3, it is estimated that the total static settlement is about 1 inch, and the differential settlement is about half of total settlement. AGS recommends that settlement calculations be evaluated if an improvement soil technique is conducted. Existing Soil Without Improvements If shallow foundations are supported on existing subsurface materials without soil improvements, some settlements are anticipated. The implications and potential adverse effects of settlement, under static and seismic loading conditions, require consideration of alternative methods of structural support, particularly deep (pile) foundations. The primary consolidation of the highly compressible soils underlying the site is estimated to be complete; therefore, settlements of the soft soils under their own weight are expected to be negligible. It is anticipated that additional settlements will occur as a result of additional grading and loading at the project site. The majority of the static settlements will be time dependent and will result from consolidation of the soft soils. Walnut Grove Water System 30 November 2012

37 The magnitude and time rate of the settlements will depend upon the thickness of the soft soils. The weight of the new tank and the stored water (assuming the tank supported on shallow/mat foundation) will result in the compression of the in-situ soils. In estimating static settlement at location of Boring B-1, AGS assumed dead plus live load of 1.7 ksf, soft soil thickness of 7 feet, an undrained shear strength of 80 psf (obtained from the data in Boring B-1), and average compression index of 0.5 (based on published information for soft peaty soils of Sacramento/San Joaquin delta area). AGS estimated the static settlement using the above mentioned parameters and assuming moisture content of the compressible soils ranges between 30 to 70 percent. Table 6 summarizes AGS estimate of both primary and secondary static settlements. TABLE 6 ESTIMATE OF PRIMARY AND SECONDARY STATIC SETTLEMENTS Boring ID Primary Static Settlement Time Required to complete Primary Static Settlement (year) Secondary Settlement Time Required to complete Primary Static Settlement* (years) (inches) (inches) 50% 90% B *After completion of construction and assuming full tank. We understand that the proposed 5000-gallon horizontal hydropneumatic tank will be constructed on two concrete saddles supported by a mat foundation. Size of the mat foundation is unknown at the time of preparation of this report. We assumed dead plus live load of 0.8 ksf based on typical dimensions of a 5000-gallon horizontal tank, replacement of the upper 7 feet of the soils by structural fill materials, and 2-foot thick mat foundation. Using the above assumptions, the estimated primary and secondary static settlements will be about half of the values indicated in Table 6. Differential static settlement for shallow/mat foundation estimated to be about one half (1/2) of the total value. Over-excavation, surcharging with or without wick drains before Walnut Grove Water System 31 November 2012

38 construction may be used to reduce the amount of time-dependent settlements, if soil improvement techniques is not taken Seismically-Induced Settlements As discussed previously, liquefaction of the in-situ, loose, saturated sandy fill may occur and would result in liquefaction-induced settlement. The seismically-induced settlement will be in addition to the static settlement, if additional structures are planned to be added. The details of seismically-induced settlements are presented in Section CORROSION POTENTIAL Based on the resistivity measurements of two samples, the subsurface materials were classified as mildly corrosive to corrosive. Based on sulfate measurements results, concrete containing Type II cement can be used for the construction of the proposed foundations. Pile caps will be in the peat or above existing ground surface. The corrosive materials may adversely affect the driven steel pile and pile caps. Mitigation measures such as coating or sacrificial thickness should be considered for protection of the steel drivel piles and pile caps. A corrosion engineer should be consulted to evaluate the effects of the corrosive soils and to provide mitigation procedures alternatives. 3.9 CONSTRUCTION CONSIDERATIONS General Although the information in this report is primarily intended for the design engineers, the subsurface data will also be useful to the bidders and contractors. However, it is the responsibility of the bidders and contractors to evaluate soil and groundwater conditions independently and to develop their own conclusions and designs regarding Walnut Grove Water System 32 November 2012

39 excavations, grading, site improvements, foundation installation, and other construction or safety aspects Effects on Adjacent facilities The effect of vibration on adjacent structures, during the construction of driven pile, should be analyzed. If the vibrations due to construction of driven piles (and possible settlement) are not tolerated with adjacent structures, a vibration free or low-vibration piling system (such as Screw-in Piling or Press-in Piling) should be used. In these lowvibration systems, a pile is screwed or pushed into the strata, with the resulting skin friction and end bearing capacities similar to driven piles. During pile driving operations, the magnitude of ground movement and the potential risk of damage to adjacent structures mainly depends on the level of vibration (particle velocity), the number of vibration cycles, the in-situ density of the soil, the distance to the adjacent structures, and the type of foundation. The particle velocity should not exceed 0.5 cm/sec near the locations of the foundations of the existing adjacent structures or pipelines. If vibration-free piles are used, it is recommended that an indicator pile program be undertaken to ascertain the driving resistance and verify the pile capacities across the site and to obtain field data for the selection of production pile lengths. Monitoring of pile driving using a Pile Driving Analyzer (PDA) during the indicator program is recommended to evaluate refusal criteria, to ascertain the stresses in the pile during driving, to estimate damage to the proposed piles during driving, and to develop additional data as to the ultimate pile capacity. AGS recommends that an indicator pile program of at least 2 piles be performed for the proposed improvement. The piles should be driven using a diesel hammer developing at least 70,000 footpounds of rated energy. For preliminary estimating purposes, a practical refusal of 60 blows per 1 foot or 40 blows per 1 foot for the last 3 feet of penetration is assumed, Walnut Grove Water System 33 November 2012

40 provided the hammer delivers at least 80 percent of the rated energy. It is further recommended that the same size and type of hammer should be used for indicator and production pile driving. During excavations adjacent to the existing structures, care should be taken to adequately support facilities that might be affected by the proposed construction procedures. Underpinning will be required where excavations extend below an imaginary plane sloping at 1:1 downward and outward from the edge of existing foundations. Construction-induced settlements of existing structures are discussed in Section AGS recommends that driven piles to be constructed prior to construction of the utilities Geotechnical Services During Construction AGS recommends that the geotechnical engineer review the geotechnical aspects of design during the design process. Furthermore, AGS recommends that earthwork, excavation, and foundation construction be monitored during construction by a licensed geotechnical engineer. This would include services during the following operations: Site Preparation and earthwork; Foundation construction, including excavations for footings; Placement and compaction of fill and backfill; Pile foundation construction; and Pipe placement and backfilling construction; The soil conditions encountered during construction should be observed to verify the applicability of the recommendations presented in this report, and to recommend appropriate changes in design or construction procedures if conditions differ from those described herein. In the early stages of construction, representative samples of fill material should be submitted to AGS for testing to establish that they will be suitable for use. Field density Walnut Grove Water System 34 November 2012

41 tests should be taken during subgrade preparation and placement and compaction of fill to make sure moisture and compaction requirements are met. Walnut Grove Water System 35 November 2012

42 4.0 CLOSURE This report has been prepared in accordance with generally accepted professional geotechnical engineering practice for the exclusive use of the MWH for the proposed water storage tank project in Walnut Grove, California. No other warranty, express or implied, is made. The analyses and recommendations submitted in this report are based upon the data obtained from the boring drilled for this study. The nature and extent of variations from the borings may not become evident until construction. In the event variations occur, it will be necessary to reevaluate the recommendations of this report. It is the responsibility of the owner or its representative to ensure that the applicable provisions of this report are incorporated into the plans and specifications, and that the necessary steps are taken to see that the contractor carry out such provisions. Respectfully submitted, AGS, Inc. No. C66379 No. GE2792 Exp. 6/30/2014 REGISTERED PROFESS IONAL KA MRAN GHIASSI ENGINEER STATE GE O T E C H N C OF I V I L & CAL Kamran Ghiassi, Ph.D. I C A L I A I FORN Keyvan Fotoohi, Ph.D. Geotechnical Engineer #2792 Geotechnical Engineer #2774 Walnut Grove Water System 36 November 2012

43 5.0 REFERENCES Abrahamson, N., Atkinson, G., Boore, D., Bozorgnia, Y., Campbell, K., Chiou, B., Idriss, I.M., Silva, W., and Youngs, R. (2008), Comparison of the NGA Ground Motion Relations, Earthquake Spectra, 24, Abrahamson, N.A. and Silva, W.J. (2008), Summary of the Abrahamson & Silva NGA Ground-Motion Relations, Earthquake Spectra, 24, AWWA D100-11, American Water Works Association, effective date: July 1, Boore, D.M. and Atkinson, G..M. (2008), Ground-Motion Prediction Equations for the Average Horizontal Component of PGA, PGV, and 5%-Damped PSA at Spectral Periods Between 0.01s and 10.0 s, Earthquake Spectra, 24, Borchardt, G. and Toppozada, T.R., Relocation of the A1836 Hayward Fault Earthquake to the San Andreas Fault. EOS Transactions, 1996 Fall Meeting, American Geophysical Union, vol. 77, no. 46. Brabb, E.E. and Pampeyan, E.H., Preliminary Geologic Map of San Mateo County, California. U. S. Geological Survey, Miscellaneous Field Studies Map MF-328, 1:62,500. Campbell, K.W. and Bozorgnia, Y. (2008), NGA Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01 to 10 s, Earthquake Spectra, 24, Chiou, B.S.J. and Youngs, R.R. (2008), An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra, Earthquake Spectra, 24, Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and Wills, C.J., 2003, The Revised 2002 California Probabilistic Seismic Hazard Maps, June 2003; California Geological Survey. URL: http: // _parameters / pdf /2002_CA_Hazard_Maps.pdf. Walnut Grove Water System 37 November 2012

44 Hryciw 1995; Stewart et al. 1997; Boulanger et al. 1997; Mitchell et al. 1998b Idriss, I.M., Selection of Earthquake Ground Motions at Rock Sites, Report Prepared for the Structures Division, Building and Fire Research Laboratory, National Institute of Standards and Technology. Department of Civil Engineering, UC Davis, September. Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas with Locations and Ages of Recent Volcanic Eruptions. CDMG Geologic Data Map No.6. Petersen, M.D., Bryant, W.A., Cramer, C.H., Cao, T., and Reichle, M.S., Probabilistic Seismic Hazard Assessment for the State of California. California Division of Mines and Geology, Open File Report 96-08; U. S. Geological Survey, Open File Report Real, C.R., Toppozada, T.R., and Parke, D.L., Earthquake Epicenter Map of California. California Division of Mines and Geology, Map Sheet 39, 1:1,000,000. Seed, H.B., and Idriss, I.M., Ground Motions and Soil Liquefaction During Earthquakes. Earthquake Engineering Research Institute Monograph. Toppozada, T.R., Real, C.R., and Park, D.L., Preparation of Isoseismal Maps and Summaries of Reported Effects for pre-1900 California Earthquakes. California Division of Mines and Geology, Open File Report SAC. Working Group on California Earthquake Probabilities, Earthquake Probabilities in the San Francisco Bay Region: 2000 to A Summary of Findings. Open File Report , version 1.0. Walnut Grove Water System 38 November 2012

45 PLATES

46

47

48 Reference: MARSTON, N EARTH LOAD COEFFICIENTS FOR PIPELINE DESIGN AGS, Inc. CONSULTING ENGINEERS PROPOSED STORAGE WATER TANK WALNUT GRAVE, CALIFORNIA PROJECT NO.: AGS DATE: 9/2012 PLATE 3

49 Reference: NAVFAC DM VERTICAL SURCHARGE PRESSURES AGS, Inc. CONSULTING ENGINEERS PROPOSED STORAGE WATER TANK WALNUT GRAVE, CALIFORNIA PROJECT NO.: AGS DATE: 9/2012 PLATE 4

50 Reference: MARSTON, N LATERAL SURCHARGE PRESSURES POINT AND LINE LOADS PROPOSED STORAGE WATER TANK AGS, Inc. CONSULTING ENGINEERS WALNUT GRAVE, CALIFORNIA PROJECT NO.: AGS DATE: 9/2012 PLATE 5

51 Reference: MARSTON, N LATERAL SURCHARGE PRESSURES AREAL LOADS AGS, Inc. CONSULTING ENGINEERS PROPOSED STORAGE WATER TANK WALNUT GRAVE, CALIFORNIA PROJECT NO.: AGS DATE: 9/2012 PLATE 6

52 Lateral Loads at Top of Piles (kips) Deflection at Top of Piles (inches) 0 Deflection (inches) Moment (kip-feet) Soil Reaction (kips/feet) Shear (kips) Depth Below Pile Head (feet) Notes: This evaluation applies to piles 90 feet long. Modulus of Elasticity of concrete was used E=1,847ksi. This plate may be used for vertical loads up to 75 kips. Sign Conventions (direction of positive load, moment, and shear) Plate Project No.: AGS Date: Oct

53 APPENDIX A FIELD EXPLORATION AND SAMPLING

54 A.1 EXPLORAT TION AGS obtained a drilling permit through the County of San Mateo Environmental Health Department, and notified Underground Service Alert (USA) for utilities to be marked relative to each proposed boring location. Drilling was performed by Geoex Subsurface Exploration of Dixon, California, using a rotary wash truck-mounted CME 75 drilling rig with a 5-inch diameter bit. The drilling spoils were placed inside 55-gallon drums, sealed, and after analytical test results on a composite soil sample were available, transported from the site. The subsurface conditions encountered in the borings were continuously logged in the field during drilling operations by a geologist from AGS. Plate A Log of Borings B-1 gives descriptions and graphic representations of the encountered materials, the depths at whichh samples were obtained, and the laboratoryy tests performed. The legend to the logs is shown on Plate A-2 - Soil Classification Chart and Key to Test Data. A.2 SAMPLING Soil samples, as appropriate for the various earth materials encountered, were collected using standard penetration test (SPT), modified California (MC) samplers, and Shelby Tube samplers. Samples were typically collectedd at least once in each 5-foot depth interval. Relatively undisturbed soil samples obtained with the MC sampler were collected into 2.5-inch outside diameter by 6-inch long brass or stainless steel liners. The liners were immediately capped, sealed with vinyl tape, and labeled. Soil sampless collected from the SPT sampler were placed into plastic bags andd labeled. The Shelby Tube samples were stored in approximately 30-inch long Shelbyy Tubes, capped and sealed. All the liners were kept upright and cushioned from shock. Walnut Grove Water System A-1 October 2012

55 The SPT and MC samplers were driven with a hydraulically-operated automatic 140- pound hammer, falling 30 inches for an 18-inch penetration, where possible. The blows required to advance the samplers were used to assist in classifying the apparent density of cohesionless soil deposits, and the relative consistency of cohesivee soil deposits. The blow counts equired to drive the sampler for each 6-inch increment were recorded; except where refusal was met, in whichh case the number off inches penetrated by 50 blows (typically) was recorded. The blow counts are shown on the Logs of Borings in Appendix A. The blow counts shown on the Logs of Borings are the numbers recorded in the field, and have not been corrected or adjusted. Following the completion of drilling and sampling, the boring was backfilled with cement- bentonite grout, and the ground surface was returned to its original condition to the maximum extent possible. Walnut Grove Water System A-2 October 2012

56 LOG OF BORING B-1 DRILLING DATE: 7/26/12 DRILLING METHOD: Rotary Wash w/ 5" Drag Bit DRILL RIG TYPE: CME 75 HAMMER TYPE: 140-lb, falling 30 inches SURFACE ELEVATION: ft DATUM: LOGGED BY: JF CHECKED BY: KG DEPTH (FEET) SAMPLE TYPE SAMPLE NO. BLOW COUNT GRAPHIC LOG GEOTECHNICAL DESCRIPTION AND CLASSIFICATION DRY DENSITY (PCF) MOISTURE CONTENT (%) LIQUID LIMIT (%) PLASTICITY INDEX (%) ADDITIONAL TESTS 5 1A B psi ORGANIC CLAY (OL), very dark gray, moist, very soft to soft, trace sand [TOPSOIL] ORGANIC SILT (OH), peat, dark brown and black, moist, very soft, some clay, many organics - trace fine-grained sand and shell fragments CV WA (97) UC (0.08) psi SANDY SILT(ML), dark gray, wet, very soft, little fine-grained gravel, little to some organics, little fine-grained sand, moderate organic odor CN psi 1 WOH 1 - stiffer, trace clay SILTY SAND (SM), dark gray, wet, very loose, fine-grained NP NP UC (0.48) SA (40) changed to loose 36 NP NP WA (28) POORLY GRADED SAND WITH SILT (SP-SM), dark gray, wet, loose, medium to coarse-grained micaceous sand, little fine-grained subrounded gravel 27 WA (6) POORLY GRADED SAND WITH SILT (SP-SM) continued, dark gray, wet, medium dense, medium to coarse-grained micaceous sand, trace fine-grained subrounded gravel 26 WA (6) LBG 30 AGS GPJ 10/9/ JOB NO. AGS POORLY GRADED SAND (SP) dark gray, wet, medium dense, medium to coarse-grained micaceous sand, trace fine-grained subrounded gravel (small quartz pebbles) PROJECT: Walnut Grove Water Tank SHEET 1 OF 3 23 PLATE A-1.1 SA (4)

57 LOG OF BORING B-1 DRILLING DATE: 7/26/12 DRILLING METHOD: Rotary Wash w/ 5" Drag Bit DRILL RIG TYPE: CME 75 HAMMER TYPE: 140-lb, falling 30 inches SURFACE ELEVATION: ft DATUM: LOGGED BY: JF CHECKED BY: KG DEPTH (FEET) SAMPLE TYPE SAMPLE NO. BLOW COUNT GRAPHIC LOG GEOTECHNICAL DESCRIPTION AND CLASSIFICATION DRY DENSITY (PCF) MOISTURE CONTENT (%) LIQUID LIMIT (%) PLASTICITY INDEX (%) ADDITIONAL TESTS POORLY GRADED SAND WITH SILT (SP-SM), dark gray, wet, medium dense, medium to coarse-grained micaceous sand, trace fine-grained subrounded gravel (small quartz pebbles) WA (6) FAT CLAY (CH), grayish-green, moist, stiff, little silt WA (97) 14A SANDY FAT CLAY (CH), grayish-green, moist, stiff, consists of SILTY CLAY WITH INTERBEDDED LENSES OF POORLY GRADED SAND WITH SILT SANDY LEAN CLAY (CL), dark greenish-gray, moist, hard, lighter colored mineral staining, some fine-grained sand and silt LBG 30 AGS GPJ 10/9/ JOB NO. AGS PROJECT: Walnut Grove Water Tank SHEET 2 OF PLATE A-1.2 WA (63)

58 LOG OF BORING B-1 DRILLING DATE: 7/26/12 DRILLING METHOD: Rotary Wash w/ 5" Drag Bit DRILL RIG TYPE: CME 75 HAMMER TYPE: 140-lb, falling 30 inches SURFACE ELEVATION: ft DATUM: LOGGED BY: JF CHECKED BY: KG DEPTH (FEET) SAMPLE TYPE SAMPLE NO. BLOW COUNT GRAPHIC LOG GEOTECHNICAL DESCRIPTION AND CLASSIFICATION DRY DENSITY (PCF) MOISTURE CONTENT (%) LIQUID LIMIT (%) PLASTICITY INDEX (%) ADDITIONAL TESTS SANDY CLAY (CL), dark gray and dark green, medium-stiff, some silt, trace fine-grained sand, moderately plastic 85 17A B hard changed to very hard, few fine-grained sand, mineral staining and light cementation Boring terminated at a depth of approximately 94 feet below the existing ground surface. Estimated groundwater depth approximately 3 feet below ground surface at time of drilling. Boring backfilled with cement-bentonite grout to 3 feet below ground surface. top 3 feet was backfilled with soils cuttings. Boring elevation approximately 2.5 feet lower than existing paved building pad. Bulk sample of cuttings collected at depth of 1 to 3 feet LBG 30 AGS GPJ 10/9/ JOB NO. AGS PROJECT: Walnut Grove Water Tank SHEET 3 OF 3 PLATE A-1.3

59 MAJOR DIVISIONS TYPICAL NAMES COARSE GRAINED SOILS FINE GRAINED SOILS More than Half < #200 sieve More than Half > #200 sieve GRAVELS MORE THAN HALF COARSE FRACTION IS LARGER THAN NO. 4 SIEVE SANDS COARSE FRACTION IS SMALLER THAN NO. 4 SIEVE SILTS AND CLAYS CLEAN GRAVELS WITH LITTLE OR NO FINES GRAVELS WITH OVER 15% FINES CLEAN SANDS WITH LITTLE OR NO FINES LIQUID LIMIT LESS THAN 50 SILTS AND CLAYS SANDS WITH OVER 15% FINES LIQUID LIMIT GREATER THAN 50 GW GP GM GC SW SP SM SC ML CL OL MH CH WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES POORLY GRADED GRAVELS, GRAVEL-SAND MIXTURES SILTY GRAVELS, POORLY GRADED GRAVEL-SAND-SILT MIXTURES CLAYEY GRAVELS, POORLY GRADED GRAVEL-SAND-CLAY MIXTURES WELL GRADED SANDS, GRAVELLY SANDS POORLY GRADED SANDS, GRAVELLY SANDS SILTY SANDS, POOORLY GRADED SAND-SILT MIXTURES CLAYEY SANDS, POORLY GRADED SAND-CLAY MIXTURES INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS, OR CLAYEY SILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS ORGANIC CLAYS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACIOUS FINE SANDY OR SILTY SOILS, ELASTIC SILTS INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS UNIFIED SOIL CLASSIFICATION SYSTEM CA CV CN CP Is TS Modified California Sampler (2.5-inch I.D.) 1.5 Pocket Penetrometer - Field, tsf Standard penetration Test (1.5-inch I.D.) RV R-Value Pitcher Barrel DS Direct Shear HQ Core Barrel TX Unconsolidated Undrained Triaxial Bulk Sample (Auger Cuttings) NP Non-Plastic Sample Attempt with No Recovery UC Unconfined Compression/Uniaxial Compressive Strength Chemical Analysis (1.2) (Unconfined Strength, ksf) Corrosivity SA Sieve Analysis Consolidation WA Wash Analysis Compaction (20) (with % Passing No. 200 Sieve) Point Load Index Water Level at Time of Drilling Thin Section Analysis Water Level after Drilling (with date measured) ADDITIONAL TESTS AND KEY TO TEST DATA SOIL CLASSIFICATION CHART AND KEY TO TEST DATA Walnut Grove Water System Proposed Tank Geotechnical Investigation JOB NO. AGS DATE August 2012 PLATE A-2.1

60 APPENDIX B GEOTECHNICAL FIELD AND LABORATORY TESTING

61 B.1 GENERAL Preliminary visual soil classifications were made byy AGS in the field in accordance with ASTM D , Standard Practice for Description and Identification of Soils (Visual- were taken to AGS laboratory for examination and analyses. The soil classifications were verified by observation of the samples in thee laboratory and a testing program in Manual Procedure) ). Upon completion of drilling, the samples collected from the borings accordance with ASTM D , Standard Classification of Soils for Engineering Purposes (Unified Soil Classification System). Geotechnical field and laboratory testss were performed on selected soil and rock sampless in order to evaluatee the engineering properties of the materials. The tests includedd particle size, moisture content and densityy measurements, Atterberg limits, and consolidation tests. B.2 FIELD TESTING The blows required to drive the samplers, using a 140-pound hammer falling 30 inches for an 18-inch penetration, were used to assist in classifying the relative density of cohesionless soil deposits and the stiffness of cohesive soil deposits. Blow counts recordedd by AGS in the field are shown on the Logss of Borings. B.3 LABORATORY TESTING The laboratory tests were performed using the techniques and procedures discussed below. Walnut Grove Water System B-1 October 2012

62 B.3.1 Particle Size Particle size analyses were conducted on selectedd samples in accordance with ASTM D-422, Standard Test Method for Particle Size Analysis off Soils or ASTM D-1140, Standard Test Method for Amount of Material in Soils Finer than the No. 200 (75-µm) Sieve. The results of the particle size and wash analyses are presented on Plates B-1.1 and B-1.2, Particle Size Analysis. The amounts passing the No. 200 sieve are shown on the Logs of Borings. B.3.2 Moisture and Density Tests Moisture content and density tests were performed on selected samples to evaluate their consistenciess and the moisture variation throughout the explored profile. The moisture content was evaluated in accordance with ASTM D , Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock, and was considered to represent the moisture content of the entire sample for dry density evaluation. The test results are presented on thee Logs of Borings at the appropriate sample depth, in Appendix A. B.3.3 Atterberg Limits Atterberg limits were evaluated on selected cohesive, fine-grained soil samples to assist in their classificatio on. Liquid limits, plastic limits, and plasticity indices were evaluated in accordance with ASTM D-4318, Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. The resultss of the Atterberg limits tests are included in the Plasticity Chart in Appendix B, Plate B-2.1. Liquidd limits and plasticity indices are also shown on the Logs of Borings, in Appendix A. Walnut Grove Water System B-2 October 2012

63 B.3.4 Consolidatio on Tests Consolidation testss were performed on selected undisturbedd soil samples, by Cooper Testing Laboratory of Palo Alto, California, to evaluate theirr consolidation properties. The tests were conducted in accordance with ASTM D2435 Standard Test Method for One-Dimensional Consolidati on Properties of Soil.. The Consolidation test resultss are shown on Plates B-3.1 and B-3.2. The major constraint regarding choice of samples was the presence of shells affecting the results. B.3.5 Unconfined Compressiv ve Strength Tests Unconfined compressive strength testss were performed on selected cohesive soil sampless to evaluate their strength characteristics. The tests weree conducted in accordance with ASTM D-2166, Standard Test Method for Unconfined Compressive Strength of Cohesive Soil. The unconfined compressive strength test results are shown on Plates B-4.1 and B-4.2. Walnut Grove Water System B-3 October 2012

64 100 U.S. SIEVE OPENING IN INCHES / /4 3/8 4 6 U.S. SIEVE NUMBERS HYDROMETER P E R C E N T F I N E R B Y W E I G H T GRAIN SIZE IN MILLIMETERS GRAVEL SAND COBBLES SILT OR CLAY coarse fine coarse medium fine SAMPLE SOURCE CLASSIFICATION MC% LL PL PI Cc Cu 5.0' Organic Silt (OH) ' Sandy Silt (ML) 18.5' Silty Sand (SM) 36 NP NP NP 26.0' Poorly Graded Sand with Silt (SP-SM) ' SAMPLE SOURCE 5.0' Poorly Graded Sand with Silt (SP-SM) 26 D100 D60 D30 D10 %Gravel %Sand %Silt %Clay ' ' ' ' PARTICLE SIZE ANALYSIS Walnut Grove Water Tank Walnut Grove, California JOB NO. AGS DATE Oct 2012 PLATE B-1.1

65 100 U.S. SIEVE OPENING IN INCHES / /4 3/8 4 6 U.S. SIEVE NUMBERS HYDROMETER P E R C E N T F I N E R B Y W E I G H T GRAIN SIZE IN MILLIMETERS GRAVEL SAND COBBLES SILT OR CLAY coarse fine coarse medium fine SAMPLE SOURCE CLASSIFICATION MC% LL PL PI Cc Cu 38.5' Poorly Graded Sand (SP) ' Poorly Graded Sand with Silt (SP-SM) ' Fat Clay (CH) ' Sandy Lean Clay (CL) SAMPLE SOURCE 38.5' D100 D60 D30 D10 %Gravel %Sand %Silt %Clay ' ' ' PARTICLE SIZE ANALYSIS Walnut Grove Water Tank Walnut Grove, California JOB NO. AGS DATE Oct 2012 PLATE B-1.2

66 CH PLASTICITY INDEX (PI) CL 20 MH or OH 10 CL-ML ML or OL LIQUID LIMIT (LL) SAMPLE SOURCE CLASSIFICATION LIQUID LIMIT (%) PLASTIC LIMIT (%) PLASTICITY INDEX (%) % PASSING #200 SIEVE 5.0' Organic Silt (OH) ' Silty Sand (SM) NP NP NP 18.5' Silty Sand (SM) NP NP NP ' Fat Clay (CH) ' Sandy Lean Clay (CL) PLASTICITY CHART Walnut Grove Water Tank Walnut Grove, California JOB NO. AGS DATE Oct 2012 PLATE B-2.1

67 Consolidation Test ASTM D2435 Job No.: Boring: B1-4 Run By: MD Client: AGS Sample: Reduced: PJ Project: AGS Depth, ft.: 7-9(Tip-9") Checked: PJ/DC Soil Type: Dark Greenish Gray CLAY w/ Sand Date: 8/31/2012 Strain-Log-P Curve 0.0% 5.0% 10.0% Strain, % 15.0% 20.0% 25.0% Effective Stress, psf Ass. Gs = 2.75 Initial Final Moisture %: Dry Density, pcf: Void Ratio: % Saturation: Remarks: The 550 psf point was shifted to 600 psf due to regulator drift. PLATE B-3.1

68 UNCONFINED COMPRESSIVE STRENGTH (psf) STRAIN (%) Sample Source Classification Type of Test Ultimate Strength (psf) Strain (%) Dry Density (pcf) Moisture Content (%) 5.0' Organic Silt (OH) UC = Unconfined Compression UNCONFINED COMPRESSIVE STRENGTH Walnut Grove Water Tank Walnut Grove, California JOB NO. AGS DATE Oct 2012 PLATE B-4.1

69 UNCONFINED COMPRESSIVE STRENGTH (psf) STRAIN (%) Sample Source Classification Type of Test Ultimate Strength (psf) Strain (%) Dry Density (pcf) Moisture Content (%) 12.5' Silty Sand (SM) UC = Unconfined Compression UNCONFINED COMPRESSIVE STRENGTH Walnut Grove Water Tank Walnut Grove, California JOB NO. AGS DATE Oct 2012 PLATE B-4.2

70 APPENDIX C CORROSIVITY TESTING

71 Corrosivity Test Summary CTL # Date: 8/22/2012 Tested By: PJ Checked: PJ Client: AGS Project: Walnut Grove Water Syst. Proj. No: AGS Remarks: Sample Location or ID 15.5 o C (Ohm-cm) Chloride Sulfate-(water soluble) ph ORP Sulfide Moisture Boring Sample, No. Depth, ft. As Rec. Minimum 100% mg/kg mg/kg % (Redox) Qualitative % Soil Visual Description Saturated Dry Wt. Dry Wt. Dry Wt. mv by Lead At Test ASTM G57 Cal 643 ASTM G57 ASTM D4327 / Cal 422-mod. ASTM D4327 / Cal 417-mod. ASTM G51 SM 2580B Acetate Paper ASTM D2216 B1 Bulk , Black CLAY w/ organics B1-1A , Very Dark Brown Clayey SAND