APPENDIX B SOILS REPORT.pdf

APPENDIX B

GEOTECHNICAL REPORT

10851 EDISON CT., RANCHO CUCAMONGA, CA 91730 : 909-989-1751 : FAX 909-989-4287

GEOTECHNICAL CONSULTANTS

October 30, 2006

Lewis Operating Corp 1156 N Mountain Ave P.O. Box 670 Upland, CA 91785-0670

Attention: Mike Vachini

Subject: Geotechnical Investigation IEUA Property APN 1057-181-01 & -02 S/o Pine Ave & W/o and N/o Chino Corona Rd Chino, CA

Gentlemen:

In accordance with your request, a geotechnical investigation has been completed for the above-referenced site. The report addresses both engineering geologic and geotechnical conditions.

The results of the investigation are presented in the accompanying report, which includes a description of site conditions, results of our field exploration and laboratory testing, conclusions and recommendations.

We appreciate this opportunity to be of continued service to you. If you have any questions regarding this report, please do not hesitate to contact us at your convenience.

Respectfully submitted, RMA Group

Gary Wallace, P.G.

Vice President

CEG 1255

Ed Lyon, P.E.

President

GE 2362

GEOTECHNICAL INVESTIGATION

FOR

IEUA PROPERTY APN 1057-181-01 & -22

S/O PINE AVE & W/O AND N/O CHINO CORONA RD

CHINO, CA

for

Lewis Operating Corp 1156 N Mountain Ave P.O. Box 670 Upland, CA 91785-0670

06-107-01

Lewis Operating Corp.

IEUA Property

RMA Job Nº: 06-107-01 Page i

TABLE OF CONTENTS

PAGE

1.00 INTRODUCTION 1

1.01 Purpose 1

1.02 Scope of the Investigation 1

1.03 Site Location and Description 1

1.04 Current and Past Land Usage 2

1.05 Planned Usage 2

1.06 Investigation Methods 3

2.00 FINDINGS 3

2.01 Geologic Setting 3

2.02 Earth Materials 3

2.03 Expansive Soils 4

2.04 Surface and Ground Water Conditions 4

2.05 Faults 4

2.06 Seismicity 5

2.07 Flooding Potential 6

2.08 Regional Land Subsidence and Fissure Potential 7

2.09 Organic Soils, Manure and Methane Gas 7

2.10 Landslides 7

3.00 CONCLUSIONS AND RECOMMENDATIONS 8

3.01 General Conclusion 8

3.02 General Earthwork and Grading 8

3.03 Earthwork Shrinkage and Subsidence 8

3.04 Removals and Overexcavation 8

3.05 Rippability and Rock Disposal 10

3.06 Subdrains 10

3.07 Fill and Cut Slopes 10

3.08 Faulting 10

3.09 Seismic Design Parameters 10

3.10 Liquefaction and Secondary Earthquake Hazards 11

3.11 Slab and Foundation Design 11

3.11.01 Stiffened Reinforced Slab on Grade 12

RMA Job Nº: 06-107-01 Page ii

TABLE OF CONTENTS

(continued)

PAGE

3.11.02 Post Tensioned Slab on Grade 13

3.12 Miscellaneous Concrete Flatwork 13

3.13 Footing Excavation and Slab Preparations 14

3.14 Lateral Loads 14

3.15 Drainage and Moisture Proofing 15

3.16 Cement Type and Corrosion Potential 16

3.17 Temporary Slopes 17

3.18 Utility Trench Backfill 19

3.19 Pavement Sections 20

3.20 Plan Review 21

3.21 Geotechnical Observation and Testing During Rough Grading 21

3.22 Post-Grading Geotechnical Observation and Testing 21

4.00 CLOSURE 22

FIGURES AND TABLES

Figure 1 Site Location Map Figure 2 Regional Geologic Map Figure 3 Fault and Earthquake Epicenter Map Figure 4 Boring Location Map Table 1 Notable Faults within 100 Km Table 2 Historical Strong Earthquakes

APPENDICES

Appendix A Field Investigation A1 Appendix B Laboratory Tests B1 Appendix C General Earthwork and Grading Specifications C1 Appendix D Liquefaction and Dynamic Settlement Analysis D1 Appendix E References E1

RMA Job Nº: 06-107-01 Page 1

1.00 INTRODUCTION

1.01 Purpose

A geotechnical investigation has been completed for a proposed residential development to be constructed at the subject site. The purpose of the investigation was to summarize geotechnical and geologic conditions at the site, to assess their potential impact on the proposed development, and to develop geotechnical and engineering geologic design parameters.

1.02 Scope of the Investigation

The general scope of this investigation included the following:

• Review of published and unpublished geologic, seismic, ground water and geotechnical literature.

• Review of a previous geotechnical investigation completed by this firm (RMA Group, 2002), which is a part of the site. Three borings were completed within the northeastern part of the site and are included with this report, along with laboratory results from soil samples obtained from these borings.

• Examination of aerial photographs.

• Contacting of underground service alert to locate onsite utility lines

• Logging, sampling and backfilling of 16 exploratory borings drilled with model CME-55 hollow stem auger drill rig.

• Laboratory testing of representative soil samples.

• Geotechnical evaluation of the compiled data.

• Preparation of this report presenting our findings, conclusions and recommendations.

Our scope of work did not include a preliminary site assessment for the potential of hazardous materials onsite.

1.03 Site Location and Description

The site is located in the city of Chino, California. It is bounded by Chino Corona Road to the south and west, agricultural fields to the east, a small dairy to the northwest and Pine Avenue to the north.

The site consists of a dairy manure composting facility in the main southern portion of the site and a small fenced agricultural field in the northeast corner of the site. Access to the composting facility is by means of either Chino Corona Road from the south or a road from the northeast leading from Pine Avenue. Access to the fenced agricultural field is through a gate in the northeast corner. The approximate location of the site is illustrated on the accompanying Site Location Map (Figure 1).

RMA Job Nº: 06-107-01 Page 2

Topographically, the majority of the property is planar, sloping to the southeast at about a 2-3% grade. Elevations range from approximately 566 to 590 feet above sea level. Drainage is by means of sheet flow. There is a large drainage basin in the southern part of the composting facility.

Man-made features consist of several buildings associated with the composting facility in the northern portion of the site, truck scales and a scale house on the eastern side of the site, artificial fill piles and soil berms, and asphaltic concrete roads. A 10 to 12 feet deep detention basin is located in the southern portion of the site. The majority of the composting facility is covered by a layer of soil cement and asphalt.

Vegetation consists primarily of several small and large trees along the perimeter of the site and along access roads.

1.04 Current and Past Land Usage

Current Usage of the Site

The main southern portion of the site is currently utilized as a bio-solid and dairy manure composting facility. At the time of our field exploration the composting facility had recently ceased operation and clean up of the site was ongoing. The agricultural field in the northeast portion of the site was fallow at the time of our field exploration.

Past Usage of the Site

In the past, the site was used as agricultural fields. Aerial photograph research revealed that the site was utilized as an agricultural field back to at least 1955. Aerial photographs from 1955 to 1978 reveal two small buildings in the northwest corner of the site. The buildings are no longer present in 1986 or later aerial photographs. The former building sites are now part of an agricultural field.

During the review of the aerial photographs there was no visible evidence of that the site was used as a dairy or of past standing water.

Past Usage of Nearby Properties

The properties to the west and northeast have been used as small dairies and dairy pasture since at least the 1950’s. Aerial photographs taken prior to 1996 show that the properties to the south of the site was generally used for agriculture field crops, and that it ranged from planted and fallow field to areas covered with a sparse native brush. Aerial photographs taken in February of 1986 show an area of standing water northeast of the site.

1.05 Planned Usage

Our investigation was performed prior to the preparation of grading or foundation plans. To aid in preparation of this report we utilized the following assumptions:

RMA Job Nº: 06-107-01 Page 3

• Foundation loads of 3 kips per linear foot for continuous footings and 60 kips for spread footings.

• Cuts and fills will be less than 10 feet.

1.06 Investigation Methods

Our investigation consisted of office research, field exploration, laboratory testing, review of the compiled data, and preparation of this report. It has been preformed in a manner consistent with generally accepted engineering and geologic principles and practices, and has incorporated codes, ordinances, regulations and laws that, in our professional opinion, are applicable. Definitions of technical terms and symbols used in this report include those of the American Society for Testing and Materials (ASTM D653 & D4879), the Uniform Building Code, and standard geologic references.

Technical supporting data are presented in the attached appendices. Appendix A contains a description of the methods and equipment used in performing the field exploration and logs of our subsurface exploration. Appendix B contains a description of our laboratory testing and the test results. Standard grading specifications and references are presented in Appendices C and D, respectively.

2.00 FINDINGS

2.01 Geologic Setting

The site is located in the upper Santa Ana River Valley of the Peninsula Ranges geomorphic province. According to the California Department of Water Resources (1970), the site is underlain by approximately 300 feet of alluvium.

The upper Santa Ana River Valley is bordered by the San Gabriel Mountains and the active Cucamonga fault to the north, and the Puente Hills and potentially active Chino fault to the west.

To the south are the Jurupa Mountains and other resistant granitic and metamorphic hills. The eastern boundary of the valley is the San Bernardino Mountains and the active San Andreas fault.

The Geologic setting of the site is illustrated on Figure 2.

2.02 Earth Materials

Our subsurface investigation and review of geologic literature revealed that the site is underlain by artificial fill, soil cement, asphalt and older alluvium.

The artificial fill consisted of soil berms along the periphery of the composting facility up to 5 feet in height, a soil pile in the northeastern corner of the composting facility about 10 to 14 feet in

RMA Job Nº: 06-107-01 Page 4 height. A berm composed of soil and manure was located in the center of the composting facility running from near the structures in the north to the detention basin in the south.

The soil cement covered the composting facility to a depth ranging from less than one inch to 14 inches in thickness. A few of our borings encountered no soil cement within the western portion of the composting facility. The asphalt covered the eastern half of the composting facility, the detention basin and access roads to the composting facility and was generally 2 inches in thickness.

The alluvium consists of silty clays underlain by silty sands, clayey sands and sands. The silty clay locally contains small, off-white carbonate nodules and stringers to depths of about ten feet. Within this zone the silty clays are slightly porous. The silty sands, clayey sands and sands below are non-porous and dense.

The above materials are described in greater detail on the logs contained in Appendix A.

2.03 Expansive Soils

Expansion testing performed in accordance with UBC Standard 18-2 indicates that earth materials underlying the site have an expansion classification of very low and medium. Results of the testing are presented in Appendix B. Since site grading will redistribute earth materials, potential expansive properties should be verified at the completion of rough grading.

2.04 Surface and Ground Water Conditions

No areas of ponding or standing water were present at the time of our study. Further, no springs or areas of natural seepage were found.

Perched ground water was encountered in Borings B-1, B-2, B-3, and B-7 at depths of 13, 11, 31, and 25 feet, respectively. According to the California Division of Mines and Geology Special Report 113 (Fife and others, 1976), the site was located in an area of artesian of rising water in the early 1900’s. The California Department of Water Resources (1970) report indicates that the depth to ground water beneath the site was about 10 to 20 feet in 1933 and about 40 to 50 feet in 1960.

Carson and Matti (1985) report that the minimum depth to ground water beneath the site from 1973 to 1979 was about 65 to 70 feet, and that the minimum depth to ground water during this time period in a well located in the adjoining property to the west was 68.8 feet. The Chino Basin Watermaster (1999) reports the depth to ground water beneath the site in the fall of 1997 was about 50 to 60 feet.

2.05 Faults

The site is not located within the boundaries of an Earthquake Fault Zone for fault-rupture hazard as defined by the Alquist-Priolo Earthquake Fault Zoning Act. No faults are known to pass through the property.

RMA Job Nº: 06-107-01 Page 5

The nearest fault system is the Chino-Central Avenue fault zone. The Central Avenue segment of this system is postulated to exist as a subsurface trace about 2 miles southwest of the site at its nearest point. The Chino segment of this system is located approximately 3 miles southwest of the site at its nearest point. The accompanying Fault and Earthquake Epicenter Map (Figure 3) illustrates the location of the site with respect to major faults in the region. The distance to notable faults within 100 kilometers of the site is presented on Table 1.

2.06 Seismicity

The site is located in a seismically active area, as is the case throughout Southern California. At this time it is not possible to state with certainty when and where future large magnitude earthquakes will occur, or what the magnitude and intensity of these events will be. However, estimates can be made based on tectonic data and seismic history. The seismic setting of the site has been evaluated by review of historic seismicity, by deterministic methods, by probabilistic methods and by code procedures.

Historic Earthquakes Strong earthquakes that have occurred in this region in historic time are summarized in Table 2 and illustrated on Figure 3. The nearest of these historic earthquakes was the magnitude 5.5 Upland Earthquake of 1990. It was epicentered approximately 13 miles to the north. Estimated peak horizontal ground acceleration at the site from the historic strong earthquakes listed on Table 2 is estimated to have ranged from about 0.07g to 0.26g.

Deterministic Evaluation

The California Division of Mines and Geology (Petersen et. al., 1996 and 1998) has compiled earthquake parameters related to faults in California. The information represents a consensus of many scientists and an interpretation of earthquake hazard parameters most accepted within the greater earth-science community. Activity of faults with reported displacement during latest Pliestocene and Holocene time was evaluated using slip rates and recurrence intervals from paleoseismic investigations. Postulated maximum earthquake magnitudes were assigned to each fault based on rupture of an entire fault segment, or in the case of Class “A” faults, rupture of multiple segments. Lengths and geometry of faults, along with other information, were also compiled. The geometries, magnitudes, slip rates and recurrence intervals reported by Petersen for faults within 100 kilometers of the site are summarized in Table 1. Anticipated peak horizontal ground accelerations for the postulated maximum moment magnitude earthquake of each fault are also present in Table 1. Using deterministic methods, it is anticipated that the most intense ground shaking at the site would result from a nearby large magnitude earthquake along the Chino-Central Avenue fault. Should a magnitude 6.7 earthquake occur along the Chino-Central Avenue fault at a point near the site, it is estimated that the peak horizontal ground acceleration at the site could be about 0.52g.

RMA Job Nº: 06-107-01 Page 6

Probabilistic Evaluation

A probabilistic analysis has been performed using Version 3.01b of the FRISKSP computer program developed by Thomas F. Blake (1998). Results of such an analysis are dependent upon a number of factors, including the attenuation relationship, soil characteristics, and fault data. For this analysis we have selected the attenuation relationship of Boore et al. (1997), a soil site classification (average shear velocity = 310 m/sec), a fault search radius of 100 kilometers, and fault data based on a modified version of the California Division of Mines and Geology fault data base for southern California. This analysis indicates a mean peak horizontal ground acceleration of 0.54g for a 10% probability of occurrence in 50 years.

Additional probabilistic seismic hazard analysis has been performed using the 2003 California Geological Survey interactive probabilistic seismic hazard map. This analysis yielded a peak horizontal ground acceleration of 0.48g for a 10% probability of occurrence in 50 years.

Seismic Coefficients and Near Source Factors

The 2001 California Building Code presents seismic data in terms of seismic zones, factors, sources and coefficients, and soil profiles. Utilizing information generated by this investigation and data from the California Division of Mines and Geology (Petersen, Et. al., 1998), the following parameters may be used to determine 2001 CBC seismic coefficients (Ca and Cv) and near-source factors (Na and Nv):

California Building Code Seismic Parameters Closest Distance to Known Seismic Source: 3.5 km

Seismic Source and Type: Chino-Central Ave fault, Type B Seismic Zone: 4

Seismic Zone Factor: 0.4 Soil Profile: SD

2.07 Flooding Potential

According to Federal Emergency Management Agency, FEMA (2001), the site does not lie within the boundaries of a 100-year flood zone. However, the county of San Bernardino does not show the site as being located within the limits for flood hazard on their Geologic Overlays Sheets (1990).

Control of surface runoff originating from within and outside of the site should, of course, be included in design of the project.

The Prado Dam Flood Control Basin lies to the south of the site. The dam’s spillway is to be raised from an elevation of 543 feet to 563 feet. Low-lying areas upstream of the dam at or below an elevation of 543 feet are encompassed within the current dam inundation zone. When the new spillway is completed the inundation zone will raise to 563 feet. Therefore, the site does not lie within the limits of upstream inundation from the Prado Dam as the site elevations range from

RMA Job Nº: 06-107-01 Page 7 about 566 to 590 feet. It also appears that the site is elevated above the future inundation level of the Dam; however, this should be verified by the design civil engineer since the elevation differences are small.

2.08 Regional Land Subsidence and Fissure Potential

According to the Chino Basin Watermaster (Wildermuth, 2002), an interformetric synthetic aperature radar survey detected no relative change in land surface elevation within the site from 1993 to 1999, and no fissures are known to exist within the property. In addition, surface or subsurface fissures suggestive of land subsidence within the site were not observed or found during our field investigation.

2.09 Organic Soils, Manure and Methane Gas

Stockpiled manure was present during our field investigation along the east side of the site and thinly spread across the surface of the agricultural field to a depth of a few inches or less.

Soils containing organic contents above 2% were encountered throughout the site to depths of 7 feet. Dark brown soils with an organic odor was encountered within several of our borings to depths ranging from 2 to 4 feet.

Soils encountered underlying the upper dark brown soils noted above, are soils containing naturally occurring calcium carbonate stringers and nodules. Calcium carbonate is a carbon based mineral and therefore yields test results that identify it as organic material when tested in accordance with ASTM D2974. These calcium carbonate bearing soils contained no other visible organic materials (manure or plant material), but tested at greater than 2% total organic content in some samples due to the presence of the calcium carbonate.

The calcium carbonate stringers and nodules were most likely formed as a result of historical high groundwater in the area and the leaching of naturally occurring minerals present within the alluvial soils. The calcium carbonate stringers and nodules present in the soils are independent of current land usage as a composting facility, as evidenced by the presence of these soils on nearby sites with no prior dairy use. The calcium carbonate stringers and nodules are not biodegradable and/or methane generating.

A methane gas survey was not a part of this study.

2.10 Landslides

Due to the low gradient of the site and surrounding area, landsliding is not a hazard at this property.

RMA Job Nº: 06-107-01 Page 8

3.00 CONCLUSIONS AND RECOMMENDATIONS

3.01 General Conclusion

Based on specific data and information contained in this report, our understanding of the project and our general experience in engineering geology and geotechnical engineering, it is our professional judgment that the proposed development is geologically and geotechnically feasible.

This is provided that the recommendations presented below are fully implemented during design, grading and construction.

3.02 General Earthwork and Grading

All grading should be performed in accordance with the General Earthwork and Grading Specifications outlined in Appendix C, unless specifically revised or amended below.

Recommendations contained in Appendix C are general specifications for typical grading projects and may not be entirely applicable to this project. Earthwork should also be in accordance with all applicable City of Chino requirements.

3.03 Earthwork Shrinkage and Subsidence

Shrinkage is the decrease in volume of soil upon removal and recompaction expressed as a percentage of the original in-place volume. Subsidence occurs as natural ground is densified to receive fill. These factors account for changes in earth volumes that will occur during grading. Our estimates are as follows:

• Shrinkage factor = 5%-10% for soil removed and replaced as compacted fill.

• Subsidence factor = 0.1- 0.2 feet.

The estimates do not include any removal of organic soils. The degree to which fill soils are compacted and variations in the insitu density of existing soils will influence earth volume changes.

Consequently, some adjustments in grades near the completion of grading could be required to balance the earthwork.

3.04 Removals and Overexcavation

All vegetation, trash and debris should be cleared from the grading area and removed from the site.

Prior to placement of compacted fills, all non-engineered fills and loose, porous, or compressible soils will need to be removed down to competent ground. Removal and requirements will also apply to cut areas, if the depth of cut is not sufficient to reach competent ground. Removed and/or overexcavated soils may be moisture-conditioned and recompacted as engineered fill, except

RMA Job Nº: 06-107-01 Page 9 for soils containing detrimental amounts of organic material. Estimated depths of removals are as follows:

• If any manure is present at the surface it will have to be stripped and hauled from the site prior to rough grading operations.

• Non-engineered fill was encountered as berms around the composting facility and as a soil pile in the northeastern corner of the composting facility. Complete removal of these fills and underlying compressible native soils will need to be performed. If other non-engineered fills are encountered during grading, they will also need to be removed along with any underlying compressible native soils.

• Loose, porous and compressible native soils were encountered to depths of about 5 to 7 feet below existing grades over the majority of the site. The average depth of removal of these soils is expected to be 5 to 7 feet with, possibly, some local areas extending to about 8 to 10 feet below the existing ground surface or the base of existing non-engineered fill.

• Soils disturbed by demolition of existing structures will need to be over-excavated to competent native ground and then scarified to a minimum depth of 12 inches, moisture conditioned and compacted to at least 90 percent of the maximum dry density

• The asphalt and concrete currently onsite may be either processed and placed in the compacted fill, or hauled off the site. If the asphalt and concrete is use as fill material, it must be broken down to approximately 4 to 8-inch particles and mixed thoroughly with on-site soils. No large and flat pieces are to be used for fill. If asphalt is processed by grinding, it cannot be used in fills and must be removed from the site.

In addition to the above requirements, overexcavation will also need to meet the following criteria for the building pads, concrete flatwork and pavement areas:

• All footing areas, both continuous and spread, shall be undercut, moistened, and compacted as necessary to produce soils compacted to a minimum of 90% relative compaction to a depth equal to the width of the footing below the bottom of the footing or to a depth of 3 feet below the bottom of the footing, whichever is less. Footing areas shall be defined as the area extending from the edge of the footing for a distance of 5 feet.

• All floor slabs, concrete flatwork and paved areas shall be underlain by a minimum of 1 foot of soil compacted to a minimum of 90% relative compaction.

The above overexcavation recommendations apply to both areas to receive fill and cuts areas.

Overexcavated soils, except soils with organic matter percentage of more than 2%, may be moisture-conditioned and recompacted as engineered fill. The base of all overexcavations and removals shall be scarified an additional 1 foot, moisture conditioned and recompacted to at least 90% of the maximum dry density.

RMA Job Nº: 06-107-01 Page 10

The above recommendations are based on the assumption that soils encountered during field exploration are representative of soils throughout the site. However, there can be unforeseen and unanticipated variations in soils between points of subsurface exploration. Hence, overexcavation depths must be verified, and adjusted if necessary, at the time of grading. The removed and/or overexcavated materials may be moisture conditioned and re-compacted as engineered fill.

3.05 Rippability and Rock Disposal

Our exploratory borings were advanced without difficulty and no oversize materials were encountered in our subsurface investigation. Accordingly we expect that all earth materials will be rippable with conventional heavy duty grading equipment and oversized materials are not expected.

3.06 Subdrains

Ground water was encountered in Borings B-1, B-2, B-3, and B-7 at depths of 13, 11, 31, and 25 feet, respectively, and the proposed grading will not fill any large canyons and the underlying soils are fairly permeable. Consequently, installation of subdrains is not expected to be necessary.

However, backdrains or weep holes are recommended for all retaining walls.

3.07 Fill and Cut Slopes

Fill and cut slopes reaching maximum heights feet of approximately 10 feet at inclinations of 2:1 (horizontal to vertical) or flatter are expected to be grossly and surficially stable. This is provided that fill slopes are properly keyed and compacted, as indicated in Appendix C, and cut slopes expose competent native soils. Cut and fill slope stability should be further reviewed upon development of a grading plan.

3.08 Faulting

Since the site is not located within the boundaries of an Earthquake Fault Zone and no faults are known to pass through the property, surface fault rupture within the site is considered unlikely.

3.09 Seismic Design Parameters

The potential damaging effects of regional earthquake activity should be considered in the design of structures. As a minimum, seismic design should be in accordance with the 2001 California Building Code (see Section 2.06) and the recommendations of the Structural Engineers Association. The structural engineer and architect should consider the seismic data presented in this report, building types, occupancy category, importance and other appropriate factors when selecting seismic design parameters.

3.10 Liquefaction and Secondary Earthquake Hazards

RMA Job Nº: 06-107-01 Page 11

Liquefaction is a phenomenon where earthquake induced ground vibrations increase the pore pressure in saturated, granular soils until it is equal to the confining, overburden pressure. When this occurs, the soil can completely loose its shear strength and enter a liquefied state. The possibility of liquefaction is dependent upon grain size, relative density, confining pressure, saturation of the soils, strength of the ground motion and duration of ground shaking. In order for liquefaction to occur three criteria must be met: underlying loose, coarse-grained (sandy) soils, a groundwater depth of less than about 50 feet and a nearby large magnitude earthquake.

Ground water was encountered within four of our borings, B-1 at 13 feet, B-2 at 11 feet, B-3 at 31 feet and B-7 at 26 feet. Borings B-1 and B-2 were advanced within an existing basin that was approximately 10 feet below the elevation of the surrounding areas. We performed an analysis (Appendix E) of the potential for liquefaction within the alluvial soils based on an assumed groundwater depth of 20 feet below existing grades for boring locations B-3 and B-7 and 10 feet below existing grades (corresponding to 20 feet below anticipated finish grades) for borings B-1 and B-2.

The results of that analysis indicate that the alluvial soils are likely to liquefy below the depth of approximately 48 feet below the existing grade in the vicinity of B-3. The magnitude of the resulting dynamic settlement is expected to be on the order of ½ inch and ¼ inch total and differential settlement, respectively, over a distance of 40 feet. No surface manifestation of liquefaction is expected at the site since the liquefiable layer below 48 feet is overlaid by non-liquefiable soils.

It is recommended that liquefaction potential be further evaluated once a grading plan and when the remainder of the site is accessible for geotechnical investigation.

Seismically induced landsliding is not expected, provided the site is properly graded and developed.

Tsunamis and seiches do not pose hazards due to the inland location of the site and lack of nearby bodies of standing water.

It should be noted that the California Geological Survey has not yet prepared a Seismic Hazard Zone Map of potential liquefaction hazards for the quadrangle in which the site is located.

3.11 Slab and Foundation Design

It is anticipated that the primary mechanisms for differential movement of building foundations at the subject site will be shrinkage and swelling of expansive soils. Our preliminary laboratory tests indicate that the expansive classification of the soils at the subject site is medium when tested in accordance with UBC Standard 18-2. Consequently, we recommend either the use of reinforced foundations and slabs with grade beams or post tensioned slab on grade at the subject site to

RMA Job Nº: 06-107-01 Page 12 mitigate the effects of expansive soils.

In addition to the structural design incorporating mitigation measures for expansive soils, the structural design must incorporate the potential settlement resulting from liquefaction. The magnitude of settlement due to liquefaction is expected on the order of ½ inch and ¼ inch total and differential settlement, respectively.

3.11.01 Stiffened Reinforced Slab on Grade

It is recommended that the design provide for a stiff floor slab, which minimizes the amount of deflection imposed on the structure. A foundation design engineer experienced in the field of slab design should undertake the design of the slabs and foundations. The slab designer should provide estimates of the anticipated deflection to the design architect and structural engineer for use in the design of the structure. If the anticipated design deflection exceeds that which the design architect and or structural engineer can accommodate then the slab should be re-designed by the slab designer to reduce the total deflection. If necessary, recommendations for alternative types of foundations may be developed by the geotechnical engineer.

A stiffened reinforced concrete slab on grade with continuous footings along the perimeter and internal grade beams may be utilized to support the proposed residence. Stiffened reinforced slabs on grade should be designed in accordance with section 1816 of the California Building Code based on an average plasticity index below the structure of 35, and the following minimum requirements.

External footings should extend to a minimum depth of 24 inches below lowest adjacent grade along the perimeter of the structure. Foundation embedment should be measured from the lowest adjacent grade within 5 feet of the structure. External footings should be continuously reinforced with a minimum of two number 5 reinforcing bars placed within 3 inches of the bottom of the footing and two number 5 reinforcing bars placed with 3 inches of the top of the footing. Internal grade beams should be placed at a maximum spacing of 15 feet on center and should be arranged to divide the structure into squares or rectangles in accordance with the requirements of section 1816 of the CBC. Internal grade beams should extend a minimum of 12 inches below the top of the slab and should have a minimum width of 12 inches.

The slab should have a minimum thickness of 5.0 inches and be designed with concrete having a minimum compressive strength of 3,000 psi. The slab should be continuously reinforced with number 5 reinforcing bars placed in both directions at a maximum spacing of 18 inches on center.

A soil moisture vapor barrier is recommended beneath all floor slabs. Due to the fine grained nature of the soils onsite, consideration should be given to construct the soil moisture vapor barrier beneath the garage slabs as well. The soil moisture vapor barrier should consist of a minimum of 4 inches of sand and a 10 mil Visqueen liner. The liner should be placed with two inches of sand below and 2 inches of sand above the liner. The liner should be carefully fitted around service openings and should be properly lapped and sealed with a minimum 6 inch overlap at joints in

RMA Job Nº: 06-107-01 Page 13 accordance with the American Concrete Institute’s (ACI) guidelines.

3.11.02 Post Tensioned Slab on Grade

An alternative method of mitigation of the effects of expansive soil may incorporate post tensioned slab on grade.

It is the responsibility of the slab designer to select the methodology utilized in the slab design. If the post tensioned slabs are designed in accordance with Chapter 18 of the California Building Code (2001 Edition) and the Post Tensioning Institute’s design procedure, the following preliminary geotechnical design parameters may be utilized:

Allowable Soil Bearing Capacity: 1,500 psf

Edge Moisture Variation Distance (Em)

Edge Lift - 5.0 feet

Center Lift - 6.0 feet

Differential Soil Movements (Ym)

Edge Lift - 1.40 inches

Center Lift - 4.60 inches

The allowable soil bearing value represents an allowable net increase in existing soil pressure for perimeter footings with a minimum width of 18 inches and a minimum depth of 24 inches below the lowest adjacent grade. Foundation embedment should be measured from the lowest adjacent grade within 5 feet of the structure.

The allowable bearing capacity may be increased by one-third for considerations of short term wind or seismic loads, and may be increased by 20% for each additional foot of depth to a maximum value of 3,500 psf. Internal footings may be embedded a minimum of 12 inches below lowest adjacent grade.

3.12 Miscellaneous Concrete Flatwork

Miscellaneous flatwork, driveways, and walkways may be designed with a minimum thickness of

5.0 inches. Flatwork, driveways, and walkways should be reinforced with number 4 reinforcing bars with maximum spacing of 18 inches on center placed at mid height in the slab. Control joints should be constructed to create squares or rectangles with a maximum spacing of 15 feet on large slab areas. Walkways should be separated from foundations with a thick expansion joint filler.

Control joints should be constructed into walkways at a maximum of 5 feet spacing.

The sub grade soils beneath all miscellaneous concrete flatwork, driveways, and walkways

RMA Job Nº: 06-107-01 Page 14 should be compacted to a minimum of 90% relative compaction for a minimum depth of 12 inches. The geotechnical engineer should monitor the compaction of the sub grade soils and perform testing to verify that proper compaction has been obtained.

3.13 Footing Excavation and Slab Preparations

All footing excavations should be observed by the geotechnical consultant to verify that they have been excavated into competent soils. The foundation excavations should be observed prior to the placement of forms, reinforcement steel, or concrete. These excavations should be evenly trimmed and level. Prior to concrete placement, any loose or soft soils should be removed. Excavated soils should not be placed on slab or footing areas unless properly compacted.

Prior to the placement of the moisture barrier and sand, the sub grade soils underlying the slab should be observed by the geotechnical consultant to verify that all under slab utility trenches have been properly backfilled and compacted, that no loose or soft soils are present, and that the slab sub grade has been properly compacted to a minimum of 90% relative compaction within the upper 12 inches.

Slabs on grade, driveway slabs and sidewalks should be brought to a minimum of 2% and a maximum of 6% above their optimum moisture content for a depth of 24 inches prior to the placement of concrete. The geotechnical consultant should perform insitu moisture tests to verify that the appropriate moisture content has been achieved a maximum of 24 hours prior to the placement of concrete or moisture barriers.

3.14 Lateral Loads

Lateral loads may be resisted by soil friction and the passive resistance of the soil. The following parameters are recommended.

• Passive Earth Pressure - equivalent fluid weight of 440 pcf.

• Coefficient of Friction (Soil to footing) – 0.43

Retaining structures should be designed to resist the following lateral active earth pressures:

RMA Job Nº: 06-107-01 Page 15

Surface Slope of

Retained Material Horiz. to Vert.

Equivalent Fluid Weight

(pcf)

Level 33

5 to 1 34

4 to 1 35

3 to 1 37

2 to 1 46

These active earth pressures are only applicable if the retained earth is allowed to strain sufficiently to achieve the active state. The required horizontal strain to achieve the active state is approximately 0.0025H. Retaining structures should be designed to resist an at rest lateral earth pressure if this horizontal strain cannot be achieved.

• At rest lateral earth pressure - 51 pcf

The horizontal compression required to achieve the full passive earth pressure is approximately 4 times the horizontal strain required to reach the active state. The horizontal compression required to reach 1/2 the maximum passive pressure is approximately equal to the horizontal strain required to achieve the active state. The previously recommended passive pressure should be reduced accordingly if the required horizontal compression to achieve full passive pressures cannot be achieved.

If any super-imposed loads are anticipated, this office should be notified so that appropriate recommendations for earth pressures may be provided.

3.15 Drainage and Moisture Proofing

It is recommended that positive drainage away from all structures be provided.

Retaining structures should be drained to prevent the accumulation of subsurface water behind the walls. Back drains should be installed behind all retaining walls exceeding 3.0 feet in height. A typical detail for retaining wall back drains is presented in Appendix C. All back drains should be outlet to suitable drainage devices. Retaining wall less than 3 feet in height should be provided with backdrains or weep holes.

Moisture proofing should be provided on all stem walls and retaining walls utilized to support structures. Special attention should be given to the design of surface drainage and moisture proofing in areas of depressed floors where the finished floor elevation within the structure lies

RMA Job Nº: 06-107-01 Page 16 below the finished pad elevation outside the structure. In these areas consideration should be given to increasing the minimum slope of the surface drainage to a minimum of 5% sloping away from structures for a minimum distance of 5.0 feet. Moisture proofing should also be provided on all site retaining walls exceeding 3.0 feet in height.

3.16 Cement Type and Corrosion Potential

Soluble sulfate tests indicate that concrete at the subject site will have a negligible exposure to water soluble sulfate in the soil. Our recommendations for concrete exposed to sulfate-containing soils are presented below.

RECOMMENDATIONS FOR CONCRETE EXPOSED TO SULFATE CONTAINING SOILS

Normal weight aggregate concrete

Lightweight aggregate concrete

Sulfate exposure

Water soluble sulfate(SO4) in soil (% by wgt)

Sulfate (SO4) in water (ppm)

Cement type

Maximum water-cement ratio by weight

Minimum compressive strength (psi)

Negligible 0.00 - 0.10 0-150 I or II -- --

Moderate 0.10 - 0.20 150-1,500 II 0.50 3,750

Severe 0.20 - 2.00 1,500-10,000 V 0.45 4,250

Very Severe Over 2.00 Over 10,000 V plus pozzolan 0.45 4,250

The soils were also tested for soils reactivity (pH) and resistivity (ohms). The test results indicate that the soils have a soil reactivity ranging from 7.31 to 7.92 and a resistivity ranging from 390 to 990 ohms-cm. A neutral or non-corrosive soil has a value ranging from 5.5 to 8.4. Generally, soils that could be considered corrosive to metal have resistivities less than 3000 ohms. Those soils with values less than 1000 ohms can be considered extremely corrosive.

In addition to the soils reactivity and resistivity, chemical processes within the soils surrounding the metal pipes can also affect the corrosion potential of buried underground piping. The soils were also tested in our previous investigation for nitrates, nitrites, and ammonia nitrogen to further evaluate the effects of the chemical corrosion potential due to the past agricultural use of the site.

The results of these tests are presented in Appendix B.

Nitrates are most commonly used as fertilizers in soils to replenish nitrogen in the soils. A nitrate is any kind of chemical compound that contains the inorganic nitrate ions. Hydrogen nitrate is most commonly known as nitric acid, an oxidizing acid. In sufficient concentrations, nitric acid will have oxidizing power to passivate pure iron. Ammonium nitrate (NH4NO3) present in many

RMA Job Nº: 06-107-01 Page 17 fertilizer solutions, may hydrolyze to form a dilute nitric acid which is consequently corrosive to copper piping.

Ammonia results from intentional additions of ammonium hydroxides (NH4OH) as an acid neutralizer. Ammonia may result from the decay of intrinsic organic humic matter or thermal degradation of nitrogen bearing inhibitors and conditioners. Although it has little effect on iron or steel alloys, it generally has a strong effect on copper alloys. When ammonia complexes form and react with copper alloys, it can cause rapid corrosion of the alloy and/or stress corrosion cracks.

Copper is generally resistant to corrosion in most soils; however, ammonia compounds may cause severe attacks. Soils containing much animal waste, sewage contamination, or ammonia may result in rapid general corrosion or stress corrosion cracks.

Based on our analysis, it appears that the underlying onsite soils will have a high corrosion potential. Protection of buried pipes utilizing coatings on all underground pipes, clean backfills and a cathodic protection system can be effective in controlling corrosion. A qualified corrosion engineer should be consulted to further assess the corrosive properties of the soil.

3.17 Temporary Slopes

Excavation of utility trenches will require either temporary sloped excavations or shoring.

Temporary excavations in existing alluvial soils may be safely made at an inclination of 1:1 (horizontal to vertical) or flatter. If vertical sidewalls are required in excavations greater than 5 feet in depth, the use of cantilevered or braced shoring is recommended. Excavations less than 5 feet in depth may be constructed with vertical sidewalls without shoring or shielding. Our recommendations for lateral earth pressures to be used in the design of cantilevered and/or braced shoring are presented below. These values incorporate a uniform lateral pressure of 72 psf to provide for the normal construction loads imposed by vehicles, equipment, materials, and workmen on the surface adjacent to the trench excavation. However, if vehicles, equipment, materials, etc.

are kept a minimum distance equal to the height of the excavation away from the edge of the excavation, this surcharge load need not be applied.

RMA Job Nº: 06-107-01 Page 18

Design of the shield struts should be based on a value of 0.65 times the indicated pressure, Pa, for the approximate trench depth. The wales and sheeting can be designed for a value of 2/3 the design strut value.

Placement of the shield may be made after the excavation is completed or driven down as the material is excavated from inside of the shield. If placed after the excavation, some overexcavation may be required to allow for the shield width and advancement of the shield. The shield may be placed at either the top or the bottom of the pipe zone. Due to the anticipated thinness of the shield

STRUTS

(typ.)

SHIELD

(typ.)

UNDISTURBED

SOIL

BEDDING

1'min.

H1

Hsh

Dt

P = 30 Hsh psfa

HEIGHT OF SHIELD, Hsh = DEPTH OF TRENCH, Dt , MINUS DEPTH OF SLOPE, H1

TYPICAL SHORING DETAIL

1:1 (H

:V) 1:1 (H:V)

SHORING DESIGN: LATERAL SHORING PRESSURES

BRACED SHEETING

H

CANTILEVERED SHEETING

72 psf

Pa Total = 72 psf + 30 H psf

Pa = 30 H psf

0.6H

0.2H

0.2H

Pa Total = 72 psf + 25 H psf

Pa = 25 H psf 72 psf

RMA Job Nº: 06-107-01 Page 19 walls, removal of the shield after construction should have negligible effects on the load factor of pipes. Shields may be successively placed with conventional trenching equipment.

Vehicles, equipment, materials, etc. should be set back away from the edge of temporary excavations a minimum distance of 15 feet from the top edge of the excavation. Surface waters should be diverted away from temporary excavations and prevented from draining over the top of the excavation and down the slope face. During periods of heavy rain, the slope face should be protected with sandbags to prevent drainage over the edge of the slope, and a visqueen liner placed on the slope face to prevent erosion of the slope face.

Periodic observations of the excavations should be made by the geotechnical consultant to verify that the soil conditions have not varied from those anticipated and to monitor the overall condition of the temporary excavations over time. If at any time during construction conditions are encountered which differ from those anticipated, the geotechnical consultant should be contacted and allowed to analyze the field conditions prior to commencing work within the excavation.

Cal/OSHA construction safety orders should be observed during all underground work.

3.18 Utility Trench Backfill

The on-site soils will not be suitable for use as pipe bedding for buried utilities. All pipes should be bedded in a sand, gravel or crushed aggregate imported material complying with the requirements of the Standard Specifications for Public Works Construction Section 306-1.2.1. Crushed rock products that do not contain appreciable fines should not be utilized as pipe bedding and/or backfill.

Bedding materials should be densified to at least 90% relative compaction (ASTM D1557-78) by mechanical methods. The geotechnical consultant should review and approve of proposed bedding materials prior to use.

The on-site soils are expected to be suitable as trench backfill provided they contain less than 3 percent organic matter. Trench backfill should be densified to at least 90% relative compaction (ASTM D1557-78) by mechanical compaction methods.

Cal/OSHA construction safety orders should be observed during all underground work.

All utility trench backfill within street right of way, utility easements, under or adjacent to sidewalks, driveways, or building pads should be observed and tested by the geotechnical consultant to verify proper compaction. Trenches excavated adjacent to foundations should not extend within the footing influence zone defined as the area within a line projected at a 1:1 (horizontal to vertical) drawn from the bottom edge of the footing. Trenches crossing perpendicular to foundations should be excavated and backfilled prior to the construction of the foundations. The excavations should be backfilled in the presence of the geotechnical engineer and tested to verify adequate compaction beneath the proposed footing.

RMA Job Nº: 06-107-01 Page 20

3.19 Pavement Sections

Sand equivalent and R-value tests were performed on anticipated subgrade soils at the site in order to provide information on their soil properties for design of pavement structural sections. Structural sections were designed using the procedures outlined in "Design Procedures for Flexible Pavements", State of California Planning Manual - Part 7. This procedure uses the principle that the pavement structural section must be of adequate thickness to distribute the load from the design traffic index (TI) to the subgrade soils in such a manner that the stresses from the applied loads do not exceed the strength of the soil (R-value).

Laboratory testing of representative samples indicates that the subgrade soils have a Resistance (R) Value of 33 and 52.