TABLE OF CONTENTS /FLD7R Kleinfelder

TABLE OF CONTENTS CHAPTER PAGE 1 INTRODUCTION 1 1.1 Proposed Construction 1 1.2 Purpose and Scope of Services 2 1.2.1 Geologic and Seismic Hazards 2 1.2.2 Geotechnical Engineering Exploration 3 2 SITE CONDITIONS 4 2.1 Surface 4 2.2 Subsurface 4 2.3 Groundwater 5 3 GEOLOGY 6 3.1 Regional Geology 6 3.2 Local Geology 6 3.3 Faulting 7 4 GEOLOGIC HAZARDS ASSESSMENT 8 4.1 Surface Fault Rupture 8 4.2 Ground Shaking 8 4.3 Liquefaction 9 4.3.1 Dynamic Compaction 10 4.4 Compressible and Collapsible Soils 10 4.5 Landslides and Slope Instability 10 4.6 Flooding, Tsunami and Seiche 11 4.7 Expansive Soils 11 4.8 Conclusions 12 5 CONCLUSIONS AND RECOMMENDATIONS 13 5.1 Conclusions 13 5.2 Site Preparation 14 5.2.1 Stripping and Grubbing 15 5.2.2 Removals 15 5.2.3 Existing Utilities, Wells, and/or Foundation 15 5.2.4 Scarification and Recompaction 15 5.3 Reinforced Soil Slope 16 5.4 Temporary excavation 17 5.4.1 General 17 5.4.2 Excavations and Slopes 17 5.4.3 Construction Considerations 18 5.5 Engineered Fill 18 5.5.1 Materials 18 5.5.2 Compaction Criteria 20 70800/FLD7R049 2007 Kleinfelder iv

5.6 Trench Backfill 20 5.6.1 Materials 20 5.6.2 Compaction Criteria 21 5.7 Foundation Design 22 5.7.1 Allowable Bearing Pressures 22 5.7.2 Estimated Settlements 23 5.7.3 Lateral Resistance 23 5.8 CBC Seismic Design Parameters 23 5.9 Soil Corrosivity 24 5.10 Interior Concrete Slabs Supported-On-Grade 25 5.11 Exterior Flatwork 27 5.12 Asphalt Concrete Pavement 28 5.13 Site Drainage 30 6 ADDITIONAL SERVICES 31 6.1 Project Bid Documents 31 6.2 Plan and Specifications Review 31 6.3 Construction Observation and Testing 32 6.4 Additional Copies of Report 32 7 LIMITATIONS 33 8 REFERENCES 35 PLATES 1 Vicinity Map 2 Site Plan and Boring Location Map 3 Geologic Map 4 Historic Seismicity 5 Typical Cross-Section APPENDIX A B C D Field Investigation Laboratory Testing Seismic Hazard Assessment Application for Authorization to Use 70800/FLD7R049 2007 Kleinfelder v

GEOLOGIC HAZARDS ASSESSMENT AND GEOTECHNICAL ENGINEERING EXPLORATION HIDDENBROOKE ELEMENTARY SCHOOL END OF ALDER CREEK ROAD VALLEJO, CALIFORNIA 1 INTRODUCTION This report presents the results of the geologic hazards assessment and geotechnical engineering exploration conducted for the proposed Hiddenbrooke Elementary School located at the end of Alder Creek Road in Vallejo, California. Our services were authorized by Mr. Mel Jordan, Facilities Planner for Vallejo City Unified School District (VCUSD) on April 21, 2006. This report includes our recommendations related to the geotechnical aspects of project design and construction. Conclusions and recommendations presented in this report are based on the subsurface conditions encountered at the locations of our explorations and the provisions and requirements outlined in the ADDITIONAL SERVICES and LIMITATIONS sections of this report. Recommendations presented herein should not be extrapolated to other areas or used for other projects without our prior review. 1.1 PROPOSED CONSTRUCTION Our understanding of the project is based on a review of the available site drawings and discussions with the project architect and civil engineer. The available plans show that the proposed project will involve construction of a new school facility including an administration/library building, multipurpose building, and 18 classrooms in five clusters of one to five classrooms. We assume that the building loads will be light to moderate and that a conventional spread footing and slab-on-grade foundation will be used to support the structures. Based on the grading plans available at the time our report was prepared, however, we understand that significant grading is proposed to develop the site. Cuts of 25 to 50 feet are planned at the eastern boundary of the site at the base of the existing slope. Fill slopes ranging from 14 to 26 feet high are planned along the western boundary of 70800/FLD7R049 1 2007 Kleinfelder

the school development to create level building pads, a park, and grades for pavement and drainage. Excavations for underground utilities are expected to be on the order of three to eight feet below existing site grade. Additional improvements will include paved parking areas, landscaping, paved and turf play areas, and underground utilities. Further details are not known to us at this time. 1.2 PURPOSE AND SCOPE OF SERVICES 1.2.1 Geologic and Seismic Hazards This evaluation is directed toward compliance with the recommended guidelines for geologic/seismic reports defined by the California Geological Survey (CGS) Note 42, Guidelines to Geologic/Seismic Reports, Note 44, Guidelines for Preparing Engineering Geologic Reports, Note 48, Checklist for the Review of Engineering Geology and Seismology Reports for California Public Schools, Hospitals, and Essential Services Buildings, Guidelines for Evaluating and Mitigating Seismic Hazards in California, CGS Special Publication 117, and the requirements of the California Code of Regulations, Title 24, 2001, California Building Code. The scope of our services for the geologic and seismic hazards assessment was outlined in our proposal to VCUSD dated March 17, 2006 (reference File No. 40-YP6-055), and included the following: Researching readily available geologic and seismic reports and maps of the area; Review of stereoscopic pairs of aerial photographs; Performing a probabilistic seismic hazard analysis to develop site-specific seismic design criteria in terms of peak ground accelerations for the Design Basis Earthquake (DBE) and the Upper Bound Earthquake (UBE); A brief reconnaissance of the site by our engineering geologist to observe surface features; Evaluation of geologic conditions including the results of the borings and laboratory testing of soil samples completed during the geotechnical investigation; Evaluation of liquefaction and landslide potential based on our exploratory borings as required by CGS Special Publication 117; and, 70800/FLD7R049 2 2007 Kleinfelder

Preparation of a written report for the site with conclusions and recommendations as required regarding geologic hazards and suitability of the site for the proposed development including site-specific geologic and seismologic maps. 1.2.2 Geotechnical Engineering Exploration The scope of our services was outlined in our proposal to the VCUSD and included the following: A review of available subsurface information contained in our files pertinent to the proposed construction and project site. Exploration of the subsurface conditions at various locations within the area of the proposed construction utilizing fifteen drilled borings and twelve backhoe test pits. Limited laboratory testing of representative samples obtained during the field investigation to evaluate relevant engineering parameters of the subsurface soils. Engineering analyses on which to base our recommendations for the design and construction of the geotechnical aspects of the project. Preparation of this report which includes: A description of the proposed project A description of the surface and subsurface site conditions encountered during our field investigation Recommendations related to the geotechnical aspects of: Site preparation and engineered fill Site grading and landslide mitigation Temporary excavations and trench backfill Foundation design and construction California Building Code (CBC) seismic site coefficients for use in structural analysis Lateral earth pressures for low retaining structures Concrete slabs supported-on-grade Asphalt concrete pavement sections Site drainage Appendices, which include summaries of our field investigation and laboratory testing programs. 70800/FLD7R049 3 2007 Kleinfelder

2 SITE CONDITIONS 2.1 SURFACE The proposed school site is located at the southern end of Alder Creek Road in the Hiddenbrooke residential development in Vallejo, California. The site is located in a narrow valley with a moderately steep natural slope along the eastern boundary and Alder Creek along the western boundary. A portion of the project area is presently vacant land that was formerly a walnut orchard. Topography is variable across the site with elevations ranging from 285 feet above mean sea level (MSL) in the creek bottom to approximately 355 feet MSL at the upper portions of the slopes. The ground generally slopes from east to west toward Alder Creek and to the south along the creek bottom. 2.2 SUBSURFACE In general, materials encountered in our borings and test pits consisted of layers of medium to very stiff silty and sandy clays to the maximum depths explored of approximately 56½ feet below existing site grade in the borings and 13 feet in the backhoe test pits. Variably weathered mudstone or claystone was encountered in many of the borings and test pits located near the toe of the slope at depths ranging between 1 and 21 feet below existing ground surface. Layers of silty and/or clayey sand, 2 to 10 feet thick, were encountered at various depths in about one-third of the borings and test pits. These layers were loose to medium dense in relative density and were generally fine to coarse grained. Laboratory testing indicates that the clayey soils are moderately to highly expansive. An Expansion Index test on a sample of near surface clay material collected from Test Pit TP-4 resulted in an Expansion Index of 90 suggesting a high potential expansion. A Plasticity Index test conducted on deeper clay with sand at Boring B-12 resulted in a Plasticity Index of 36, suggesting high plasticity and expansion potential. 70800/FLD7R049 4 2007 Kleinfelder

2.3 GROUNDWATER Free groundwater was not encountered in the borings or test pits during our field investigation. It should be noted that groundwater and soil moisture conditions within the area will vary depending on rainfall, irrigation practices, construction, runoff, or other factors not apparent at the time of our field investigation. Our boring and test pit locations are shown on the Boring Location Plan, Plate 2. A discussion of the field investigation and laboratory testing programs is presented in Appendices A and B, respectively of this report. Detailed descriptions of the subsurface conditions encountered during our field investigation are presented on the Logs of Borings, Plates A-2 through A-17 and the Logs of Test Pits, Plates A-18 through A-33 of Appendix A. 70800/FLD7R049 5 2007 Kleinfelder

3 GEOLOGY 3.1 REGIONAL GEOLOGY The project site is located in the North Coast Range Geomorphic Province of California. The northwest-trending ridges and intervening valleys in the region are controlled by the structure of the Coast Ranges, which consists of northwest-trending folds and faults. The Northern Coast Ranges contain mostly Mesozoic and Cenozoic sedimentary rocks. This region has undergone a complex geologic history of sedimentation, volcanism, folding, faulting, uplifting, and erosion. According to the theory of plate tectonics, these features result from the collision of the Farallon and North American plates and subsequent translational shear along the San Andreas Fault system. Most of the uplift in the Coast Ranges occurred by Middle Miocene time (roughly 16 million years ago), with some uplift continuing through the Quaternary (the last 2 million years). 3.2 LOCAL GEOLOGY The site is located near the central portion of Sky Valley a narrow, northwest-trending valley within Sulphur Spring Mountain that is underlain by Great Valley Sequence (map symbol: Ku) material of early to late Cretaceous age (Graymer, et.al., 1999). The Great Valley Sequence is generally composed of interbedded carbonaceous-biotite wacke, white-mica-carbonaceous sandstone, greenish-gray mudstone and shale, and laminated fine-grained sandstone and gray shale. In the study area the formation was observed to consist mainly of variably weathered mudstones and shales. Structurally, the bedding generally strike northerly with moderate to steep dips towards the east; however, some overturned bedding has been mapped east of the site dipping steeply towards the west. The structure of the immediate area is complex due to thrust faulting, and fault truncated anticlines and synclines. The lower, flatter portions of the site are overlain by alluvial fan and fluvial deposits Pleistocene age (map symbol: Qpaf). These deposits typically consist of brown, stiff to very stiff clays, dense, gravelly and clayey sand or clayey gravel that fines upward to 70800/FLD7R049 6 2007 Kleinfelder

sandy clay. The deposits display variable sorting and are located along local stream channels. A geologic map showing the site location is shown on Plate 3. 3.3 FAULTING Vallejo is situated in a region traditionally characterized by few active faults and low to moderate seismic activity. The closest significant fault is the Concord-Green Valley fault is located at about 5.2 km to the east. In addition, the West Napa Fault is located approximately 7.3 km northwest of the site. Locations of the significant active and potentially active faults are shown on Plate 4 along with historical seismicity with earthquake magnitudes 4 or greater during the last 207+ years. A major seismic event on these or other nearby faults may cause substantial ground shaking at the site. 70800/FLD7R049 7 2007 Kleinfelder

4 GEOLOGIC HAZARDS ASSESSMENT A discussion of specific geologic hazards that could impact the site is included below. The hazards considered include: surface fault rupture, seismic shaking, seismically induced ground failures (liquefaction, lateral spreading, dynamic compaction, and landslides), tsunami, seiche, and flooding (seismically induced or otherwise). 4.1 SURFACE FAULT RUPTURE Based on the information provided in Hart and Bryant (1997), the site is not within an Alquist-Priolo Earthquake Fault Zone. Based on our review of the Graymer et. al. geologic map and seismologic reports and maps for the area, no known active, or potentially active faults cross or project toward the site. Additionally, no evidence of active faulting was visible on the site during our site reconnaissance, therefore, it is our opinion that the potential for fault-related surface rupture at the existing school site is low. 4.2 GROUND SHAKING Future ground motions at the site for purposes of structural design and evaluation of liquefaction potential have been analyzed in accordance with the 2001 California Building Code (CBC), CGS Note 48, and Guidelines for Evaluating Seismic Hazards (CGS SP117, 1996). These guidelines and policies consistently require the use of Probabilistic Seismic Hazards Analysis (PSHA) methods to estimate ground motions for the Design Basis Earthquake (DBE, or 10% probability of exceedance in 50 years) and the Upper Bound Earthquake (UBE, or 10% probability of exceedance in 100 years) for public schools (K 12) or hospitals. Our seismic hazard analysis is presented in Appendix C, and concludes that the DBE and the UBE horizontal ground acceleration values are 0.51g and 0.62g, respectively. 70800/FLD7R049 8 2007 Kleinfelder

4.3 LIQUEFACTION Soil liquefaction is a condition where saturated, granular soils undergo a substantial loss of strength and deformation due to pore pressure increase resulting from cyclic stress application induced by earthquakes. In the process, the soil acquires mobility sufficient to permit both horizontal and vertical movements if the soil mass is not confined. Soils most susceptible to liquefaction are saturated, loose, clean (relatively free of clay), relatively young and fine-grained sand deposits. The condition therefore requires the coexistence of susceptible soils, strong ground motions, and shallow groundwater. Within alluvial deposits, sand units conducive to liquefaction may occur as broad layers, confined lens shaped bodies, or elongated sinuous channel deposits. The thickness of such units can vary significantly as well. In areas where strong seismic shaking has occurred, clean and loose gravel deposits have been known to liquefy as well. The primary factors affecting liquefaction potential of a soil deposit are: (1) level and duration of seismic ground motions; (2) soil type and consistency; and (3) depth to groundwater. Soils beneath the site are described on the basis of regional geologic and soils literature along with onsite borings and test pits extending to 55 feet bgs, where weathered bedrock was encountered. Data from the borings and test pits were utilized to assess the liquefaction potential of site soil deposits. The majority of the sand layers were encountered near the ground surface and those at depth do not appear saturated. Information obtained from the borings and test pits at the project site indicate an absence of groundwater beneath the site as presented in the geotechnical report. As such, in our opinion the potential for liquefaction beneath the site is low to nil. The site is adjacent to an existing creek with banks that are approximately 15 feet high. The proposed grading for the site shows that fills on the order of 10 to 15 feet high will be constructed near the top of the creek bank. 70800/FLD7R049 9 2007 Kleinfelder In our opinion, based on the clayey nature of the natural near-surface soils and the proposed engineered fill, the potential for lateral spreading is low. We have also analyzed the clay and silt layers based on the recent clay criteria by Seed et al (2003). Our analysis shows that the silt and clay layers at depth are not susceptible to liquefaction due to relatively moderate plasticity of the fines. In the absence of liquefaction, there should be no appreciable seismicallyinduced settlement in the soils beneath the site.

4.3.1 Dynamic Compaction Another type of seismically-induced ground problem that can occur as a result of seismic shaking is dynamic compaction, or seismic settlement. Such phenomena typically occur in unsaturated, loose granular material or uncompacted fill soils. Since our borings did not encounter these types of soils, dynamic compaction is not anticipated at this site. 4.4 COMPRESSIBLE AND COLLAPSIBLE SOILS Compressible soils are soils that possess low density and are, therefore, incapable of supporting significant vertical loads. Compressible soils tend to coincide with younger, Holocene deposits that have not had sufficient time to densify or become indurated or cemented. Alluvial fan deposits mapped in the region are late Pleistocene-age and have a low potential for being compressible. Collapsible soils are those that have not been subjected to high moisture under current loading conditions and densify when wetted. Mudflows, windblown deposits (i.e. loess), and other hydraulically deposited soils are often susceptible to collapse. Soils within this area were deposited by alluvial conditions and are not expected to be collapsible. 4.5 LANDSLIDES AND SLOPE INSTABILITY Landslides, varying in size from a few tens of feet to several hundreds of feet wide, are present in the general area, as well as on the easterly slopes of the site. The slides on site consist of both recent active slides, as well as older slide deposits. The unstable slide material is within areas underlain by highly fractured Great Valley Sequence material. The thinly bedded shales typically slake, or decompose rapidly, when exposed to water at the surface, thereby resulting in slope instability. The approximate limits of the slides identified on the subject site are shown on Plate 2. Further discussions and recommendations for landslide remedial work is presented in subsequent sections of this report. Indications of soil creep, which is the imperceptibly slow downslope movement due to gravity and cyclic soil shrinkage and swelling of expansive soil, were also noted on the easterly slopes. Such movements lead to higher than typical lateral pressures against 70800/FLD7R049 10 2007 Kleinfelder

retaining walls and can result in downslope movement of shallow based structures, such as fences and concrete slabs-on-grade. Remedial methods to control soil creep include: the over-excavation and replacement with non-expansive soils; and, the design of new structures to resist the additional lateral soil pressures that will be generated by expansive soils, are discussed within this report. 4.6 FLOODING, TSUNAMI AND SEICHE The Flood Insurance Rate Map, Community Panel Number 060631-0425-B, dated August 2, 1982, prepared by the Federal Emergency Management Agency, indicates that the subject site is located within Flood Zone C. This is the zone designation for areas of minimal flooding potential. Tsunamis, or seismic tidal waves, are caused by off shore earthquakes that can trigger large, destructive sea waves. Since the subject site is not located sufficiently close to the coastline, and to the site s topographic elevation, damage from tsunamis is not considered to be a potential seismic hazard. Seiches are caused when earthquake ground motions cause water to oscillate from one side to the other of a closed or partially closed body of water such as a lake, bay or channel. Since no such feature is located at or adjacent to the proposed campus, damage due to seiche development is not considered to be a potential seismic hazard. 4.7 EXPANSIVE SOILS Expansive soils are characterized by their ability to undergo significant volume change (shrink or swell) due to variations in moisture content. Changes in soil moisture content can result from rainfall, landscape irrigation, utility leakage, roof drainage, perched groundwater, drought, or other factors and may cause unacceptable settlement or heave of structures, concrete slabs supported-on-grade, or pavements supported over these materials. Depending on the extent and location below finished subgrade, these soils could have a detrimental effect on the proposed construction. Near-surface soils at the site consist of medium plasticity to high plasticity clay with variable amounts of silt and sand, underlain by silty clay and clayey and silty sands based on the results of our Expansion Index and Plasticity Index tests. 70800/FLD7R049 11 2007 Kleinfelder With proper

preparation as recommended in subsequent sections of this report, these soils are not expected to adversely affect project performance. 4.8 CONCLUSIONS Based on the results of our study, the site should not be adversely affected by any known geologic hazards. 1. The site is not within any current Alquist-Priolo Earthquake Fault Zone. There are no known faults or shear zones extended through the site that would endanger the development due to ground rupture. 2. The potential for adverse impacts due to liquefaction of the alluvial soils at the site is considered low because of the discontinuous nature of the sandy layers encountered in our test borings and the presence of a significant thickness of non-liquefiable soils above the potentially liquefiable layers. 3. The potential for landslides or other downslope earth movements is very low due to the relatively flat topography. 4. The inland location for the site makes damage due to tsunamis or seiches unlikely. 5. The Flood Insurance Rate Map, Community-Panel Number 060631-0425-B, dated August 2, 1982, prepared by the Federal Emergency Management Agency, indicates that the site is in Flood Zone C, which is designated for areas of minimal flooding. 70800/FLD7R049 12 2007 Kleinfelder

5 CONCLUSIONS AND RECOMMENDATIONS 5.1 CONCLUSIONS Based upon the results of our exploration, it is our opinion that the site is suitable for the proposed development from a geotechnical engineering standpoint, provided the recommendations presented in this report are incorporated into the final plans and specifications for the subject project. We conclude that there are no known geologic hazards that would preclude the proposed development. It is highly likely that the site will be subject to moderate to strong seismic shaking during the lifetime of the facility. The U.S. Geological Survey (USGS) Working Group on California Earthquake Probabilities determined that there is a 62% chance of at least one magnitude 6.7 or greater earthquake occurring in the San Francisco Bay region prior to 2032 (Working Group, 2003). To minimize the potential for structural distress, the new improvements should be designed and constructed according to the most current earthquake resistance standards for Seismic Zone 4, as outlined in the California Building Code and Uniform Building Code. A key consideration for development of the school site will be mitigation of the landslide conditions on the slope to the east. Based on our evaluations, it appears that the bulk of the landslide material will be removed by the proposed grading. The surficial landslide deposits that will remain at the top of the slope will need to be buttressed. In addition, the bedrock that will be exposed in the cut slope is prone to instability and will require treatment to provide a stable slope face. We understand that there are designated wetlands present on the site in areas that will be developed. Some of these wetlands will be removed by the proposed grading and others will need to be avoided. The grading contractor should review information pertinent to the wetlands and plan their activities for conformance to the wetland mitigation/avoidance plans. 70800/FLD7R049 13 2007 Kleinfelder

Based on our experience in the area, cut slopes in natural materials should be no steeper than three (3) horizontal to one (1) vertical (3(h):1(v)). The current grading plan shows a proposed 2(h):1(v) cut, which is too steep for the materials. We understand that because of site constraints the slope can not be cut flatter. As such, a reinforced slope should be used. Our initial evaluation indicates that a reinforced soil slope cut be constructed at a 1½(h):1(v) inclination. Preliminary recommendations for a reinforced soil slope are presented in subsequent sections of this report. Also of significance to the project is the presence of near surface potentially expansive clay soils. Expansive clays are subject to shrinking and swelling, due to variations in moisture content, resulting in the potential for moderate expansion pressures. Careful compaction control and moisture conditioning will be necessary for the clayey soils. Grading specifications and structural foundation design, to minimize potential damage due to these expansive pressures, are presented. The proposed structures may be supported upon conventional continuous perimeter spread foundations and isolated interior spread foundations sized for low to moderate bearing pressures. Interior slabs-on-grade should be supported on a minimum of 12 inches of non-expansive imported fill. Discussion of these factors, as well as other recommendations for construction of the proposed improvements are presented in the following sections of this report. 5.2 SITE PREPARATION We anticipate that significant cutting and filling will be required during site grading. Site preparation will also include the removal of existing trees and any abandoned underground utility lines. All site preparation activities, including required removals, should extend five feet horizontally beyond the limits of the proposed building pads and adjacent walkways, though we anticipate that the proposed mass grading should encompass the required overbuild. Removal of abandoned underground utility lines should include the removal of any granular trench backfill material associated with the utility line. It is important that during tree removal, the root system be removed also. The following items are recommended for preparation of the site: 70800/FLD7R049 14 2007 Kleinfelder

5.2.1 Stripping and Grubbing The site should be stripped of all organic materials within cut, fill, structural pad, and pavement areas. It is estimated that this will require the removal of one to three inches of surface soils in some areas. The organic topsoil can be stockpiled and may be used for landscaping purposes; that is, the upper one foot of material used for vegetation in areas not supporting structures or pavements. Strippings with organics should not be incorporated into any structural fill. Deeper stripping and grubbing will be necessary during tree removal to sufficiently clear out the root system. The resulting depressions should be dish shaped to allow compaction equipment to enter, and be backfilled with compacted material meeting the specifications listed below. 5.2.2 Removals All areas to receive engineered fill or to support project features should be stripped down to native, undisturbed material. After stripping and the removal of underground utility lines, if any areas or pockets of soft or saturated soils are encountered, they should likewise be over-excavated to firm native material and replaced with engineered fill constructed as recommended in this report. 5.2.3 Existing Utilities, Wells, and/or Foundation Although not encountered during our field investigation, it is possible abandoned utility lines, septic tanks, cesspools, wells, and/or foundations may exist on site. If encountered within the area of construction, these items should be removed and disposed of off-site; and existing wells should be abandoned in accordance with applicable regulatory requirements. Existing utility pipelines that extend beyond the limits of the proposed construction and that are to be abandoned in-place should be sealed with cement grout to prevent migration of soil and/or water. All excavations resulting from removal activities should be cleaned of loose or disturbed material (including all previously-placed backfill) and dish-shaped with sides sloped three horizontal to one vertical, 3(h):1(v) or flatter to permit access for compaction equipment. 5.2.4 Scarification and Recompaction All clay soils to receive engineered fill, and the structural pad at grade, should be scarified to a minimum depth of twelve inches, moisture conditioned, and recompacted 70800/FLD7R049 15 2007 Kleinfelder

to between 88 and 92 percent of the maximum dry density, as determined by the ASTM D1557 test method. The moisture content of the scarified soils to be recompacted should be at least three percent above the optimum moisture content at the time of compaction. Moisture conditioning of the clayey soils is important, as this tends to preswell the clays to reduce future expansive pressures. Over-compaction of on-site clays is not desirable, as this will increase the potential for volume changes. In-place scarification and compaction may not be adequate to densify all disturbed soil within areas grubbed or otherwise disturbed below a depth of about 8 inches. Therefore, overexcavation of disturbed soil, scarification and compaction of the exposed subgrade, and replacement with engineered fill may be required to sufficiently densify all disturbed soil. Should site grading be performed during or subsequent to wet weather, near-surface site soils may be significantly above the optimum moisture content. Additionally, it is common to encounter wet, unstable soils upon removal of site pavements or flatwork as a result of subsurface moisture becoming trapped beneath relatively impervious asphalt concrete or portland cement concrete surfaces. Perched groundwater may also develop above dense, cemented on-site soils or rock, saturating near-surface materials. These conditions could hamper equipment maneuverability and efforts to compact site soils to the recommended compaction criteria. Disking to aerate, chemical treatment, replacement with drier material, stabilization with a geotextile fabric or grid, or other methods may be required to reduce excessive soil moisture and facilitate earthwork operations. 5.3 REINFORCED SOIL SLOPE Reinforced soil slopes should be constructed in accordance with the details shown on Plate 5. The initial slope should be cut at 1.5(h):1(v) to allow a 20 feet long grid length. The required benches must be cut during grid placement, not before, to prevent degradation of the supporting material. Geogrid should be placed at a maximum two feet vertical spacing. The geogrid should be wrapped at the face of the slope as shown on. Plate 5. Engineered fill for the reinforced soil slope should be compacted to a minimum of 90 percent relative compaction based on ASTM D1557 test methods. 70800/FLD7R049 16 2007 Kleinfelder

Drains consisting of Miradrain pre-fabricated drainage board should be placed on benches at a maximum five feet vertical spacing and daylight at the slope face. Engineered fill should be placed as described in Section 5.5 below. The finished slope should be covered with an erosion control mat. 5.4 TEMPORARY EXCAVATION 5.4.1 General All excavations must comply with applicable local, state, and federal safety regulations including the current OSHA Excavation and Trench Safety Standards. Construction site safety generally is the sole responsibility of the Contractor, who shall also be solely responsible for the means, methods, and sequencing of construction operations. We are providing the information below solely as a service to our client. Under no circumstances should the information provided be interpreted to mean that Kleinfelder is assuming responsibility for construction site safety or the Contractor's activities; such responsibility is not being implied and should not be inferred. It is our professional opinion that utility trench side slopes in undisturbed clayey soils and bedrock will remain near vertical to a depth of five feet or so. It should be recognized that trench wall instability should be anticipated during times of high groundwater levels when soils are saturated or nearly saturated, and also due to moisture loss and equipment vibration. Safety of trench excavation is the responsibility of the contractor. We recommend that excavation construction practices conform to requirements presented by OSHA 29 CFR Part 1926 (Occupation Safety and Health Standards - Excavations; Final Rule). 5.4.2 Excavations and Slopes The Contractor should be aware that slope height, slope inclination, or excavation depths (including utility trench excavations) should in no case exceed those specified in local, state, and/or federal safety regulations (e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations). Such regulations are strictly enforced and, if they are not followed, the Owner, Contractor, and/or earthwork and utility subcontractors could be liable for substantial penalties. 70800/FLD7R049 17 2007 Kleinfelder

Near-surface soils encountered during our field investigation consisted predominately of silty clay. In our opinion these soils would be considered a Type B soil when applying the OSHA regulations. For this soil type OSHA recommends a maximum slope inclination of 1 horizontal to 1 vertical, 1(h):1(v), or flatter for excavations 20 feet or less in depth. Steeper cut slopes may be utilized for excavations less than five feet deep depending on the strength, moisture content, and homogeneity of the soils as observed in the field. In addition, steeper slopes are permissible in the bedrock, however, they should be monitored by an engineering geologist to document their stability during construction of the reinforced soil slope. 5.4.3 Construction Considerations Heavy construction equipment, building materials, excavated soil, and vehicular traffic should not be allowed within 1/3 the slope height from the top of any excavation. Support systems such as shoring, bracing, or underpinning may be required to provide structural stability and to protect personnel working within the excavation where stability is a concern. Shoring, bracing, or underpinning required for the project (if any) should be designed by a professional engineer registered in the State of California. During wet weather, earthen berms or other methods should be used to prevent runoff water from entering all excavations. All runoff water should be collected and disposed of outside the construction limits. Import fill material (engineered fill), if required, should be a granular, low to nonexpansive soil meeting the following requirements: 5.5 ENGINEERED FILL 5.5.1 Materials All engineered fill soils should be nearly-free of organic or other deleterious debris, essentially non-plastic, and less than three inches in maximum dimension. In general, well-graded mixtures of gravel, sand, non-plastic silt, and small quantities of rock fragments, and/or clay are acceptable for use as engineered fill. All imported fill shall be certified as clean from the source (not from former industrial sites or similar 70800/FLD7R049 18 2007 Kleinfelder

locations; not chemically affected). Guidance for characterization of imported fill for school sites is presented in the California Department of Toxic Substances Control (DTSC) guidance document entitled Information Advisory - Clean Imported Fill Material dated October 2001 (http://www.dtsc.ca.gov/schools/upload/smp_fs_cleanfill-schools.pdf). Specific requirements for engineered fill, as well as applicable test procedures to verify material suitability, are provided below. TABLE 1: ENGINEERED FILL REQUIREMENTS Fill Requirement Test Procedures Gradation ASTM 1 Caltrans 2 Sieve Size Percent 3 inch 100 D 422 202 ¾ inch 70-100 D 422 202 No. 4 50-100 D 422 202 No. 40 30-100 D 422 --- No. 50 30-100 D 422 202 No. 200 15-70 D 422 202 Plasticity Liquid Limit Plasticity Index <30 <12 D 4318 204 Organic Content Less than 3% D2974 --- Expansion Potential (UBC 18-2) Less than 20 --- --- Maximum Dry Density More than 105 pcf D1557 --- 1 American Society for Testing and Materials Standards (latest edition) 2 State of California, Department of Transportation, Standard Test Methods (latest edition) All import fill should be tested for compliance by our firm prior to delivery to the site. Import fill material should be compacted to a minimum of 90 percent, with a moisture content at or above the optimum level, as determined by the ASTM D1557 test procedures. 70800/FLD7R049 19 2007 Kleinfelder

5.5.2 Compaction Criteria All structural fills should be placed in lifts no greater than eight inches in loose thickness and compacted to a relative compaction between 88 and 92 percent of the maximum dry density, at a uniform moisture content at least three percent above the optimum moisture content at the time of compaction for clayey soils. Granular or non-cohesive soils should be compacted to a minimum of 90 percent relative compaction at a uniform moisture content at or above the optimum moisture content at the time of compaction. Compaction should be increased to at least 95 percent in the upper twelve inches in all areas to support pavement sections subject to vehicular loadings. Compaction specifications recommended above are not the only criteria for proper fill placement. Other than the degree of relative compaction and the percentage of water content, the stability of the fill material is also an important factor to the performance of the fill. A fill can be unsuitable, such as pumping, even if the fill material meets the required compaction specifications. Therefore, a fill should not be considered suitable, regardless of the degree of relative compaction, if the material is unstable. We recommend that final grading plans be reviewed by Kleinfelder for conformance to our design recommendations prior to construction bidding. All site preparation, overexcavation, fill placement and moisture conditioning should be observed and tested by a representative of our firm. 5.6 TRENCH BACKFILL In order to provide suitable support of the concrete slabs, foundations, and asphalt pavements, it is important that utility trenches passing beneath the subgrade be properly backfilled and that the backfill be compacted to an adequate density. 5.6.1 Materials Pipe zone backfill (i.e., material beneath and in the immediate vicinity of the pipe) should consist of native or imported soil less than one inch in maximum dimension; trench zone backfill (i.e., material placed between the pipe zone backfill and finished subgrade) may consist of native soil which meets the requirements for engineered fill provided above. 70800/FLD7R049 20 2007 Kleinfelder

If any areas of soft subgrade are exposed in the bottom of the trench excavation, it may be necessary to place a geotextile or geogrid such as Mirafi 500X or Tensar BX1100, respectively, or an approved equivalent, in the bottom of the excavation prior to placing pipe bedding material. Materials removed from the trenches should be suitable for use as backfill provided that they do not contain any deleterious materials or rock pieces exceeding three inches in largest dimension. If import material is used for pipe or trench zone backfill, we recommend it consist of fine-grained sand. In general, coarse-grained sand and/or gravel is not recommended and should not be used for pipe or trench zone backfill due to the potential for soil migration into the relatively large void spaces present in this type of material and water seepage along trenches backfilled with coarse-grained sand and/or gravel. If coarsegrained backfill is selected, please contact our office for additional recommendations. Recommendations provided above for pipe zone backfill are minimum requirements only. More stringent material specifications may be required to fulfill local codes and/or bedding requirements for specific types of pipes. We recommend the project Civil Engineer develop these material specifications based on planned pipe types, bedding conditions, and other factors beyond the scope of this study. 5.6.2 Compaction Criteria All trench backfill should be placed and compacted in accordance with recommendations provided above for engineered fill. Within pavement areas, trench backfill should be compacted to at least 95 percent relative compaction within 12 inches of finished subgrade. Mechanical compaction is required. Ponding or jetting is not allowed. 70800/FLD7R049 21 2007 Kleinfelder

5.7 FOUNDATION DESIGN 5.7.1 Allowable Bearing Pressures To reduce future moisture changes in the building slab subgrade, we recommend that continuous perimeter wall footings be used. It is our opinion that the anticipated structural loads may be supported upon continuous perimeter spread foundations and isolated interior spread foundations, bearing upon undisturbed firm native soil or properly constructed engineered fill. Continuous spread foundations should be at least 12 inches wide and based at least 24 inches below lowest adjacent interior or exterior grade; isolated spread foundations should have a minimum width of 24 inches and should also be based at least 24 inches below adjacent grade. Continuous and isolated footings embedded to the above-recommended depth may be designed for an allowable soil bearing pressure not exceeding 3,000 pounds per square foot for dead plus live loads. The above bearing pressures may be increased by one-third for transient loads, including either seismic or wind effects. The base of the foundation excavation, to a minimum depth of 12 inches, should be at least three percent above optimum moisture content immediately prior to the placement of concrete. The weight of foundation concrete extending below grade may be disregarded in sizing computations. To resist expansive pressure, we recommend that continuous foundations contain steel reinforcement, consisting of a minimum of four No. 4 bars, two top and two bottom. The actual foundation design and reinforcement, however, should be provided by the design engineer taking into account the structural loadings. Joints in perimeter footings or holes made for utilities, etc., should be sealed to prevent migration of moisture through the footings. Lean concrete or low permeability clay may be used. Perimeter roof gutters discharging into solid drain pipes should be used, and positive drainage away from exterior walls provided. Care should be taken to avoid the drying of soils exposed in the footing excavations. In the summer, it is important to place concrete as soon as possible to prevent loss of moisture from the foundation excavations. Moisture content of the foundation soils should be tested by a representative of Kleinfelder 24 hours prior to pouring of concrete. If the moisture contents are below that specified, foundation materials should 70800/FLD7R049 22 2007 Kleinfelder

be moisture conditioned by periodic sprinkling or flooding to achieve the recommended moisture content. 5.7.2 Estimated Settlements If existing fill is identified and properly replaced with engineered fill, we estimate that the settlement of continuous spread foundations will be in the range of ¾ inch, and the isolated footings supporting column loads on the order of ½ inch to ¾ inch. Differential settlements for foundations proportioned for the bearing value recommended above are expected to be less than half this range. The major portion of the settlement will probably occur relatively rapidly during construction with application of the dead load. 5.7.3 Lateral Resistance Resistance to lateral forces by spread foundations may be computed using either friction or passive pressure. An ultimate friction factor of 0.3 is considered appropriate between the undersurface of the concrete and the supporting subgrade. An ultimate passive earth pressure equivalent to that exerted by a fluid weighing 300 pounds per cubic foot is recommended. Factors of safety should be applied to either mode of resistance selected for design computations. If friction and passive pressures are combined, the larger value should be reduced by 50 percent for design of building foundations. This reduction factor need not be applied to the lateral resistance design of retaining wall foundations that are not a part of the structure. 5.8 CBC SEISMIC DESIGN PARAMETERS For seismic design the site ground motions will depend on the particular earthquake and the resulting site response characteristics. For this site, the closest fault is the Concord-Green Valley fault at a distance of about 5.2 km, according to the Active Fault Near-Source Zones Map E-15 which is published by the ICBO. Due to potential near fault motion resulting from activity on the Concord Green Valley fault, near-source effects should be considered in the structural design of the proposed facilities. Structures with strength discontinuities, soft stories, plan irregularities, discontinuous shear walls and ductile moment frames are particularly vulnerable to these type of motions and should either be avoided or properly evaluated. 70800/FLD7R049 23 2007 Kleinfelder

For a code based equivalent lateral force design, we recommend using the procedures provided in the 2001 CBC. The Near-Source Factors N a and N v in the code are incorporated into the seismic coefficients C a and C v, which are both used to estimate the total design lateral force or shear at the base of the building or structure. The values of these factors depend on the distance of the structure from the fault and the fault type. Parameters for input to seismic modeling are provided on the basis of information contained in this report as follows: TABLE 2: SEISMIC DESIGN PARAMETERS Seismic Design Parameter Reference Symbol Seismic Source Type 1 CBC Table 16A-U A-C B Near Source Factor 1 CBC Table 16A-S/T N a, N v 1.0, 1.2 Seismic Zone CBC Figure 16A-2 1-4 4 Seismic Factor CBC Table 16A-I Z 0.40 Soil Profile Type CBC Table 16A-J S S D Seismic Response Coefficient Recommended Value CBC /Table 16A-Q/R C a, C v 0.45, 0.78 1 Fault Activity Map of California and Adjacent Areas with Locations and Ages of Recent Volcanic Eruptions, California Division of Mines and Geology; Jennings, C.W. (1994). If the structural design requires unusual foundation configurations or imposes loads greater than those assumed in this report, our office should be contacted for possible modification to these recommendations. 5.9 SOIL CORROSIVITY A selected sample of the near-surface soil encountered at the site was submitted for chemical analysis for the purpose of corrosion assessment. The sample was tested in general accordance with California Test Methods 643, 422, and 417 for ph and resistivity, soluble chlorides, and soluble sulfates, respectively. The test results are presented in Table 3, Summary of Corrosion Test Results. 70800/FLD7R049 24 2007 Kleinfelder

Boring No. TABLE 3: SUMMARY OF CORROSION TEST RESULTS (Results pending) Sample Depth (feet) Resistivity (Ohm-Cm) ph Water Soluble Sulfates (ppm) Water Soluble Chlorides (ppm) TP-4 0-7 700 7.40 76.0 85.4 TP-6 9-12 400 7.82 6.9 632.2 According to the 2001 California Building Code, Table 19-A-4, a sulfate concentration below 0.10 percent by weight (1,000 ppm) is negligible. A water-soluble chloride content of less than 500 ppm is generally considered non-corrosive to reinforced concrete. A minimum resistivity tests performed on the soil sample indicated that the soil is considered to be corrosive to buried metal objects. A commonly accepted correlation between soil resistivity and corrosivity towards ferrous metals (NACE Corrosion Basics, 1984) is provided below: Minimum Resistivity, ohm-cm Corrosion Potential 0 to 1,000 - Severely Corrosive 1,000 to 2,000 - Corrosive 2,000 to 10,000 - Moderately Corrosive Over 10,000 - Mildly Corrosive We have provided the above preliminary corrosion tests. These tests are only an indicator of potential soil corrosivity for the samples tested. Other soils found on the site may be more, less, or of a similar corrosive nature. Kleinfelder does not practice corrosion engineering. We recommend that a competent corrosion engineer be retained to evaluate the corrosion potential of the site to proposed improvements, to recommend further testing as required, and to provide specific corrosion mitigation methods appropriate for the project. 5.10 INTERIOR CONCRETE SLABS SUPPORTED-ON-GRADE The near-surface native soils have moderate to high expansion potential and will be subject to cycles of shrinking and swelling with variations in soil moisture content. To 70800/FLD7R049 25 2007 Kleinfelder

minimize the potentially adverse effects of these soils, we recommend that the soil be prepared as discussed in the Site Preparation section of this report, and that the following recommendations are also followed. The soil subgrade should be prepared as outlined in the Site Preparation section of this report. Slabs-on-grade should be supported on a minimum of 12 inches of nonexpansive engineered fill in addition to the slab support section recommended below. It is emphasized that building floor slabs should not be constructed upon a dry subgrade. In addition, we recommend that interior floor slabs be supported upon a minimum fourinch blanket of free draining crushed rock which will serve as a capillary moisture barrier. Gradation of this material should be such that 100 percent will pass a one-inch sieve with none passing the No. 4 sieve. To reduce possible distress to the floor slab resulting from expansion pressures of subgrade soils responding to variations in moisture content, steel reinforcement should be included. The use of rebar, instead of wire mesh, would reduce the amount of possible distress. A modulus of subgrade reaction (k-value) of 100 psi/in should be used for floor slab design. The final design of slabs and reinforcement is the responsibility of the design engineer. If necessary, more stringent structural considerations should govern floor slab design. Subsurface moisture and moisture vapor naturally migrate upward through the soil and, where the soil is covered by a building or pavement, this subsurface moisture will collect. To reduce the impact of this subsurface moisture and the potential impact of introduced moisture, such as landscape irrigation or plumbing leaks, the current industry standard is to place a vapor retarder on the compacted crushed rock layer (described above). This membrane typically consists of visquene or polyvinyl plastic sheeting at least 10 mil in thickness. It should be noted that although capillary break and vapor barrier systems are currently the industry standard, this system may not be completely effective in preventing floor slab moisture problems. These systems will not "moisture proof" the floor slab nor will it assure floor slab moisture transmission rates will meet floor-covering manufacturer standards. The design and construction of such systems are dependent on the proposed use and design of the proposed building and all elements of building design and function should be considered in the slab-on-grade floor design. Building design 70800/FLD7R049 26 2007 Kleinfelder

and construction may have a greater role in perceived moisture problems since sealed buildings/rooms or inadequate ventilation may result in excessive moisture in a building and affect indoor air quality. Various factors such as surface grades, adjacent planters, the quality of slab concrete, and the permeability of the on-site soils affect slab moisture control performance. In many cases, perceived floor moisture problems are the result of improper curing of floor slabs and flooring adhesives, not excessive slab moisture transmission. We recommend contacting a flooring consultant experienced in the area of concrete slabon-grade floors for specific recommendations regarding your proposed flooring applications. Special precautions must be taken during the placement and curing of all concrete slabs. Excessive slump (high water-cement ratio) of the concrete and/or improper curing procedures used during either hot or cold weather conditions could lead to excessive shrinkage, cracking, or curling in the slabs. High water-cement ratio and/or improper curing also greatly increase the water vapor permeability of concrete. We recommend that all concrete placement and curing operations be performed in accordance with the American Concrete Institute (ACI) Manual. It is emphasized that we are not concrete slab-on-grade floor moisture proofing experts. We make no guarantee nor provide any assurance that use of the capillary break/vapor retarder system will reduce concrete slab-on-grade floor moisture penetration to any specific rate or level, particularly those required by floor covering manufacturers. The builder and designers should consider all available measures for slab moisture protection. 5.11 EXTERIOR FLATWORK Exterior concrete flatwork should be constructed upon a minimum 4-inch thick layer of Class 2 Aggregate Base Rock. The Aggregate Base should be compacted to between 90 and 95 percent relative compaction as determined by the ASTM D1557 test method. This layer should be constructed upon a moisture-conditioned subgrade as outlined above. 70800/FLD7R049 27 2007 Kleinfelder

Moisture-conditioning will help reduce, but will not eliminate, the potential for swelling of the near-surface soils; cracking and vertical movements of the slabs may still result. Sufficient clearance should be allowed for outward opening doors that swing over the exterior flatwork. If adequate clearance is not present, the door bottom may scrape across the slab and not allow the door to open fully. Exterior concrete flatwork should contain steel reinforcement with bar steel preferred over wire mesh. If wire mesh is used it should be in sheet form, as opposed to rolls. Wire mesh should be placed at the midpoint of the slab. Shrinkage crack control joints should have a minimum depth of 25% of the slab thickness. To minimize differential movements between sections, doweling at all joints is recommended. A modulus of subgrade reaction (k-value) of 100 psi/in should be used for slab on grade design. The final design of slabs and reinforcement is the responsibility of the design engineer. If necessary, more stringent structural considerations should govern slab design. 5.12 ASPHALT CONCRETE PAVEMENT One resistance value (R-value) test was performed on a representative sample of anticipated pavement subgrade materials encountered at the site. A laboratory R-value of 5 was obtained on a composite sample from TP-4, which will be the predominant fill material for the proposed paved areas, and was used in preparing the asphalt pavement section recommendations presented below. For the following asphalt concrete pavement design, the State of California 608 design method for flexible pavements was used. We utilized traffic indices of 3.5, 4.5 and 6 which are considered representative of paved play areas; parking areas for automobiles and light trucks; and aisleways for automobiles, bus and light trucks and weekly trash pick-up, respectively. These traffic indices should be reviewed by the project designer and owner to confirm that they are consistent with the actual design traffic loadings. 70800/FLD7R049 28 2007 Kleinfelder

TABLE 4: RECOMMENDED PAVEMENT SECTION ALTERNATIVES (Design R-Value = 5) Type B Asphalt Concrete Class 2 Aggregate Base (R = 78+) Traffic Index = 3.5 Alternative I 2.0 7.0 Alternative II 2.5 6.0 Traffic Index = 4.5 Alternative I 2.5 9.5 Alternative II 3.0 8.0 Traffic Index = 6 Alternative I 3.0 12.0 Alternative II 3.5 11.0 The above recommendations are considered adequate provided the following conditions are met: a. All trench backfill materials should be properly compacted as previously specified in this report. Mechanical compaction is recommended, as jetting or ponding will probably not obtain satisfactory densification. b. Subgrade soil should be stable and non-pumping at the time the baserock and asphaltic surface is placed. c. An adequate drainage system should be provided to prevent both surface water and subsurface seepage from saturating subgrade soils. This is especially important adjacent to the landscaped areas. Curbs adjacent to landscape areas should extend a minimum of three inches into the subgrade soil below the aggregate sections to reduce moisture migration into the soil subgrade. d. The top 12 inches of subgrade soils beneath the pavement should be compacted to at least 95 percent compaction at moisture content at least three percent above the optimum moisture content. 70800/FLD7R049 29 2007 Kleinfelder

e. The aggregate base material should be compacted to at least 95 percent of the relative compaction and meet the requirements of the State of California Specifications for Class 2 Aggregate Base having a minimum R-value of 78. f. The pavement section recommendations presented assume that periodic maintenance of pavements will be done, including sealing of cracks. 5.13 SITE DRAINAGE Final elevations at the site should be planned so that drainage is directed away from all foundations. Ponding of water or concentrated seepage should not be permitted under the building, adjacent to the foundation system, or under paved areas. Perimeter roof gutters connected to solid drain lines should be used, and positive drainage away from exterior wall provided. Pavement areas should be sloped and drainage gradients maintained to carry all surface water off the site. An adequate pavement drainage system should be provided to prevent both surface water and subsurface seepage from saturating pavement subgrade soils. This is especially important adjacent to the landscaped areas. Curbs adjacent to landscape areas should extend a minimum of three inches into the subgrade soil below the aggregate sections to reduce moisture migration into the soil subgrade. 70800/FLD7R049 30 2007 Kleinfelder

6 ADDITIONAL SERVICES 6.1 PROJECT BID DOCUMENTS It has been our experience contractors bidding on the project often contact us to discuss the geotechnical aspects of the project. Informal contacts between Kleinfelder and an individual contractor could result in incomplete or misinterpreted information being provided to the contractor. Therefore, we recommend a pre-bid meeting be held to answer any questions about the report prior to submittal of bids. If this is not possible, questions or clarifications regarding this report should be directed to the project Owner or his designated representative. After consultation with Kleinfelder, the project Owner (or his representative) should provide clarifications or additional information to all contractors bidding the job. 6.2 PLAN AND SPECIFICATIONS REVIEW Continued coordination between the design engineer and the geotechnical engineer is recommended to assure that the design is compatible with the soil and groundwater conditions determined by this exploration. We recommend our firm conduct a general review of final plans and specifications to evaluate that our earthwork and foundation recommendations have been properly interpreted and implemented during design. In the event we are not retained to perform this recommended review, we will assume no responsibility for misinterpretation of our recommendations. Review of project plans and specifications is not part of our current contract for this project. 70800/FLD7R049 31 2007 Kleinfelder

6.3 CONSTRUCTION OBSERVATION AND TESTING We recommend that all earthwork during construction be monitored by a representative from our office, including: Site preparation, site stripping, over-excavation, grading, and compaction of near-surface soils; Construction of the reinforced soil slope: Placement of all engineered fill and trench backfill; Construction of slab subgrades; and, Evaluation of all foundation excavations. The purpose of these services would be to provide Kleinfelder the opportunity to verify the applicability of the recommendations presented in this report to the soil, bedrock and groundwater conditions encountered during construction, and recommend appropriate changes in design or construction procedures if conditions differ from those described herein. Construction observation and testing are not part of our current contract for this project. 6.4 ADDITIONAL COPIES OF REPORT We have provided the addressee (as listed on the attached cover letter) with three (3) bound copies of this report and three copies to the Project Architect. If additional copies are required, we can provide copies at an additional cost (in accordance with our current fee schedule) after receipt of a written request from our client. Under no circumstances will we provide a copy of the report to other design consultants or contractors without written permission from our client. The above services are not included as part of this contract but can be provided by our firm when requested. 70800/FLD7R049 32 2007 Kleinfelder

7 LIMITATIONS The services provided under this contract as described in this report include professional opinions and judgments based on the data collected. These services have been performed according to generally accepted geotechnical engineering practice that exists in Solano County at the time our report was written. This report is issued with the understanding that the owner/developer choose the risk they wish to bear by the expenditures involved with the construction alternatives and scheduling that is chosen. In addition, the owner/developer should understand that there are risks of earth movement and property damage inherent in land development. We are unable to eliminate all risks; therefore, no express or implied warranty is made. This report may be used only by the client and only for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both on site and off site) or other factors may change over time, and additional work may be required with the passage of time. Any party other than the client who wishes to use this report shall notify Kleinfelder of such intended use by executing the Application for Authorization to Use which is included in the Appendix. Based on the intended use of the report, Kleinfelder may require that additional work be performed and that an updated report be issued. Non-compliance with any of these requirements by the client or anyone else will release Kleinfelder from any liability resulting from the use of this report by any unauthorized party. The conclusions and recommendations of this report are for the proposed additions to the Hiddenbrooke Elementary School campus located in Vallejo, California, as described in the text of this report. The conclusions and recommendations in this report are invalid if: The anticipated design loads change; The site grading differs from that assumed in preparing this report; The structure locations are changed; The report is used for adjacent or other property; The Additional Services section of this report is not followed; 70800/FLD7R049 33 2007 Kleinfelder

If changes of grades occur between the issuance of this report and construction; or, Any other change is implemented which materially alters the project from that proposed at the time this report was prepared. The conclusions and recommendations presented in this report are based on information obtained from the following: Fifteen test borings; Fifteen test pits; The observations of our engineering geologist and geotechnical engineer; The results of laboratory tests; Results of our previous site studies in the general area; and, Our experience on similar projects with similar soil and groundwater conditions. The exploratory test borings and pits do not provide a warranty as to the conditions which may exist on the entire site. The extent and nature of subsurface soil, bedrock and groundwater variations may not become evident until construction begins. It is possible that variations in soil and bedrock conditions and depth to groundwater could exist beyond the point of exploration, which may require additional studies, consultation, and possible design revisions. If conditions are encountered in the field during construction, which differ from those described in this report, our firm should be contacted immediately to provide any necessary revisions to these recommendations. It is the addressee s and/or developer s responsibility to see that all parties to the project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety including the Additional Services and Limitations sections. Other standards or documents referenced in any given standard cited in this report, or otherwise relied upon by the authors of this report, are only mentioned in the given standard; they are not incorporated into it or included by reference, as that latter term is used relative to contracts or other matters of law. 70800/FLD7R049 34 2007 Kleinfelder

8 REFERENCES Bailey, E.J. ed. 1996, Geology of Northern California, California Division of Mines and Geology, Bulletin No. 190. Bates, L.E., 1977, Soil Survey of Solano County, California: Agriculture, Soil Conservation Service. U.S. Department of Bryant, W.A., 1981, Fault Evaluation Report (FER-127), Cordelia Fault, Solano County, California: California Division of Mines and Geology. Bryant W.A., 1991, Supplement No. 2 to FER-127, Cordelia Fault, Solano County, California: California Division of Mines and Geology. Bryant, W.A., 1992, Fault Evaluation Report (FER-232), Southern Green Valley Fault, Solano County, California: California Division of Mines and Geology. California Building Code 2001, California Building Standards Commission. California Division of Mines and Geology, 1983, Alquist-Priolo Special Studies Zone Map for the Cordelia 7.5 Quadrangle. California Division of Mines and Geology, 1993a, Alquist-Priolo Earthquake Fault Zone Map for the Cordelia 7.5 Quadrangle. California Division of Mines and Geology, 1993b, Alquist-Priolo Earthquake Fault Zone Map for the Mt. George 7.5 Quadrangle. California Geological Survey 1997 Guidelines for Evaluation and Mitigation of Seismic Hazards in California, Special Publication 117. California Geological Survey, 2004, Note 48 Checklist for Review of Engineering Geology and Seismology Reports for California Public Schools, Hospitals and Essential Services Buildings, January 1, 2004 edition. Eaton, Jerry, 1986, Tectonic Environment of the 1892 Vacaville/Winters Earthquake, and the Potential for Large Earthquakes Along the Western Edge of the Sacramento Valley, California, U.S. Geological Survey, Open-File Report 86-370. Federal Emergency Management Agency (FEMA), 1991, Flood Insurance Rate Map, Solano County, California (Unincorporated Areas), Community-Panel Number 060631-0425-B, dated August 2, 1982. 70800/FLD7R049 35 2007 Kleinfelder

Frizzell, V.A. and Brown, R.D., 1973, Map Showing Recently Active Breaks Along the Green Valley Fault, Napa and Solano Counties, California, Miscellaneous Field Studies Map MF-743: U.S. Geological Survey, scale of 1 inch equals 4 kilometers. Graymer, R.W., Brabb, E.E., and Jones, D.L., 1999, Geology of the Cordelia and the Northern Part of the Benicia 7.5-Minute Quadrangles, California: Derived for the Digital Map Database Open-File 99-162. Hart, E.W. and Bryant, W.A. 1997, Fault-Rupture Hazard Zones in California: California Division of Mines and Geology, Special Publication 42, 1999 revised edition and Supplement 3. Harwood, David S., and Helley, Edward J., 1987, Late Cenozoic Tectonism of the Sacramento Valley, California, U.S. Geological Survey Professional Paper 1359. Harwood, David S., and Helley, Edward J., 1982, Preliminary Structure Contour Map of the Sacramento Valley, California, Showing Major Late Cenozoic Structural Features and Depth of Bedrock, U.S. Geological Survey, Open-File Report 82-737. Helley, Edward J., and Harwood, David S., 1985, Geologic Map of the Late Cenozoic Deposits of the Sacramento Valley and Northern Sierran Foothills, California, U.S. Geological Survey, Miscellaneous Field Studies Map MF-1790. Jennings, Charles W., 1994, Fault Activity Map of California and Adjacent Areas, California Division of Mines and Geology, Map No. 6, scale 1:750,000. Schwartz, P.D., 1994, New Knowledge of Northern California Earthquake Potential: in proceedings of ATC-35 Seminar on New Developments in Earthquake Ground Motion Estimation and Implications for Engineering Design Practice by Applied Technology Council, Redwood City, California, pp. 4-1 to 4-9. Seed, R.B., Cetin, K.O., Moss, R.E.S., Kammerer, A.M., Wu, J., Pestana, J.M., Riemer, M.F., Sancio, R.B., Bray, H.D., Kayen, R.E., and Faris, A., 2003, Recent Advances in Soil Liquefaction Engineering: A Unified Consistent Framework: University of California, Earthquake Engineering Research Center Report 2003-06. Sims, et. al., 1973, Preliminary Geologic Map, Solano County and Parts of Napa, Contra Costa, Marin, and Yolo Counties, California: U.S. Geological Survey, Misc. Field Studies Map MF-484, scale 1:62,500. 70800/FLD7R049 36 2007 Kleinfelder

Stein, R.S., and Eketrom, G., 1992, Seismicity and geometry of a 110-km-long blind thrust fault; part 2, Synthesis of the 1982-1985 California earthquake sequence: Journal of Geophysical Research, v. 97, part B, No. 4, p. 4865-4883. Tokimatsu, K., Seed, H.B., 1987, Evaluation of Settlement in Sands Due to Earthquake Shaking. Journal of the Geotechnical Engineering Division, ACE, Vol. 113, No. 8, August, pp. 861-878. Toppozada, T.R., and others, 1981, Preparation of Isoseismal Maps and Summaries of Reported Effects for pre-1900 California Earthquakes: California Division of Mines and Geology Open File Report 81-11 SAC. United States Geological Survey, USGS 1951 (photorevised 1980), Topographic Map of the Cordelia 7½-Minute Quadrangle, scale 1:24,000. Unruh, J.R., and Moores, E.M., 1992, Quaternary blind thrusting in the southwestern Sacramento Valley, California: Tectonics, v. 11, p. 192-203. Wakabayashi, John, and Smith, David L., 1994, Evaluation of recurrence intervals, characteristic earthquakes, and slip rates associated with thrusting along the Coast Range-Central Valley Geomorphic Boundary, California: Seismological Society of America, v. 84., No. 6, p. 1960-1970. Wesnousky, S.G., 1986, Earthquakes, Quaternary faults, and seismic hazard in California: Journal of Geophysical Research, v. 91, No. B-12, pages 12,587-12,631. Wong, Ivan G., et al., 1988 Contemporary Seismicity and Tectonics of the Northern and Central Coast Ranges-Sierran Block Boundary Zone, California, Journal of Geophysical Research, Vol. 93, No. B7, pages 7813-7833. Working Group on California Earthquake Probabilities, 2003, Earthquake Probabilities in the San Francisco Bay Region: 2003 to 2030 Summary of Findings: U.S. Geological Survey, Fact Sheet 039-03. Youd, T.L., Idriss, I.M., and 19 others, 2001, Liquefaction Resistance of Soils: Summary Report From the 1996 NCEER and 1998 NCEER//NSF Workshops on Evaluation of Liquefaction Resistance of Soils: ASCE Geotechnical and Geoenvironmental Journal, v. 127, n. 10, p. 817-833 70800/FLD7R049 37 2007 Kleinfelder

TO I-80 SITE VICINITY NOT TO SCALE K L E I N F E L D E R DATE: 5/30/2007 DRAFTED BY: S CALLAHAN PROJ. NO. 70800 FILENAME: a Copyright Kleinfelder, 2007 HIDDENBROOKE ELEMENTARY SCHOOL END OF ALDER CREEK ROAD VALLEJO, CALIFORNIA PLATE NO. 1