36C26118B0618-014.pdf

4412 SW Corbett Avenue, Portland, OR 97239

503.248.1939 Main

866.727.0140 Fax

888.248.1939 Toll-Free

www.pbsenv.com

Bend | Boise | Coos Bay | Eugene | Portland | Seattle | Tri-Cities | Vancouver | Walla Walla

Geotechnical Engineering Report VA Medical Center - Dermatology Outpatient Services 10535 Hospital Way Rancho Cordova, California

Prepared for:

Ms. Lesa Durham K.F. Davis Engineering, Inc.

530 La Gonda Way, Suite E Danville, California 94526

December 12, 2016 Project No. 73222.000

4412 SW Corbett Avenue, Portland, OR 97239

503.248.1939 Main

866.727.0140 Fax

888.248.1939 Toll-Free

www.pbsenv.com

Bend | Boise | Coos Bay | Eugene | Portland | Seattle | Tri-Cities | Vancouver | Walla Walla

Geotechnical Engineering Report VA Medical Center - Dermatology Outpatient Services 10535 Hospital Way Rancho Cordova, California

Project No. 73222.000

Prepared for:

Ms. Lesa Durham K.F. Davis Engineering, Inc.

530 La Gonda Way, Suite E Danville, California 94526

Prepared by:

Ryan White, PE, GE (OR) Geotechnical Discipline Lead

Reviewed by:

Saiid Behboodi, PE (OR), GE (OR) Principal Engineer

©2016 PBS Engineering and Environmental Inc.

9/30/17

Geotechnical Engineering Report VA Medical Center – Dermatology Outpatient Services Mather, California i

TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 General

1.2 Purpose and Scope

1.2.1 Literature and Records Review

1.2.2 Subsurface Explorations

1.2.3 Soils Testing

1.2.4 Geotechnical Engineering Analysis

1.2.5 Report Preparation

1.3 Project Understanding

2.0 SITE CONDITIONS

2.1 Surface Description

2.2 Geologic Setting

2.2.1 Regional Geology

2.2.2 Local Geology

2.2.3 Faults

Fault Zone Name

2.3 Subsurface Conditions

2.3.1 Soil and Bedrock

2.3.2 Groundwater

3.0 CONCLUSIONS AND RECOMMENDATIONS

3.1 Geotechnical Design Considerations

3.2 Seismic Design Criteria

3.2.1 Other Seismic Considerations

3.3 Shallow Foundations

3.3.1 Footing Preparation

3.3.2 Footing Embedment Depths

3.3.3 Minimum Footing Widths / Design

3.3.4 Foundation Static Settlement

3.3.5 Lateral Resistance

3.4 Floor Slabs

3.5 Ground Moisture

4.0 CONSTRUCTION RECOMMENDATIONS

4.1 Site Preparation

4.1.1 Proofrolling/Subgrade Verification

4.2 Subgrade Protection

4.2.1 Wet Weather/Wet Soil Conditions

4.2.2 Dry Weather Conditions

4.3 Excavation

4.4 Permanent Slopes

4.5 Structural Fill

4.5.1 Borrow Material

4.5.2 Import Granular Material

4.5.3 Trench Backfill

4.5.4 Stabilization Material

4.5.5 Retaining Wall Drain Backfill

4.5.6 Footing and Floor Slab Base Course

4.5.7 Aggregate Base Course

5.0 ADDITIONAL SERVICES AND CONSTRUCTION OBSERVATIONS

6.0 LIMITATIONS

7.0 REFERENCES

ii

SUPPORTING DATA

Figures

Figure 1 Vicinity Map Figure 2 Site Plan

Appendix A – Field Explorations Table A-1 Terminology Used to Describe Soil Table A-2 Key to Test Pit and Boring Log Symbols Figures A1–A3 Logs for Borings B-1 through B-3

Appendix B – Laboratory Testing Figure B1 Atterberg Limits Test Results

1.0 INTRODUCTION

1.1 General

This report presents the results of the PBS Engineering and Environmental Inc. (PBS) geotechnical engineering services for the proposed addition for the new dermatology outpatient services facility. The site location is shown on the Vicinity Map, Figure 1. The exploration locations in relation to existing and proposed site features are shown on the Site Plan, Figure 2.

1.2 Purpose and Scope

The purpose of PBS’ services was to develop geotechnical design and construction recommendations in support of the proposed new addition. This was accomplished by performing the following scope of services:

1.2.1 Literature and Records Review

PBS reviewed various relevant published geologic maps of the area for information regarding geologic conditions at the site.

1.2.2 Subsurface Explorations

PBS completed three borings at the location of the proposed addition. The borings were advanced to depths of about 20 feet below the existing ground surface (bgs); borings were logged and representative soil samples collected by a member of the PBS geotechnical staff.

1.2.3 Soils Testing

Collected soil samples were transported to our laboratory for testing that included natural moisture contents, Atterberg limits, and grain-size analyses (refer, Appendix B – Laboratory Testing).

1.2.4 Geotechnical Engineering Analysis

Data collected during the subsurface explorations, literature research, and laboratory testing were used to develop specific geotechnical design and construction recommendations.

1.2.5 Report Preparation

This Geotechnical Engineering Report summarizes the results of our explorations, testing, and analyses, including information relating to the following:

• Exploration logs and site plan showing approximate exploration locations

• Laboratory test results

• Groundwater conditions

• Foundation support recommendations

− minimum embedment − allowable bearing pressure − estimated settlement − sliding coefficient − passive earth pressure

• Seismic Design Criteria in accordance with the 2015 International Building Code

(IBC)

• Slab subgrade preparation recommendations

• Geotechnical construction considerations

1.3 Project Understanding

PBS understands the VA Medical Center plans to add new buildings southwest of the existing Buildings 645 and 646 to house the new Dermatology Outpatient Services and Eye Clinic. The new structure will be a two-story, steel-frame building. Columns loads, including dead load and long-term live loads, will be on the order of 175 kips or less. We estimate slab loads will be less than 250 psf.

The purpose of PBS’ services was to evaluate the subsurface conditions within the new building footprint and provide geotechnical information needed to develop recommendations for use in design and construction.

2.0 SITE CONDITIONS

2.1 Surface Description

The VA Medical Center is located south of John Muir Parkway, in Rancho Cordova, California.

The proposed dermatology facility addition will be located on the north side of the existing outpatient clinic, between the existing facility and Muir Road to the north.

The area is flat and is currently occupied by a parking lot with landscaped areas, trees, and concrete sidewalk. Ground surface elevations in the area range from 207 feet to 211 feet above mean sea level (AMSL), based on review of the provided site plans.

2.2 Geologic Setting

2.2.1 Regional Geology

The VA Medical Center is located in the southern end of the Great Valley geomorphic province. The province extends from the Klamath Mountains province in the north to the Transverse Ranges in the south. The Coast Ranges province consists of northwest-southeast trending valleys and mountain ranges, which roughly parallel the San Andreas Fault. (CGS, 2002)

Bedrock in the area consists of the Great Valley Sequence. The sequence consists of a layer of Cretaceous marine sedimentary rocks (predominantly shale) up to 40,000 feet thick;

this formation is overlain by up to 3,000 feet of Cenozoic sedimentary deposits derived from erosion of surrounding mountain ranges (North Coast Ranges and Sierra Nevada).

2.2.2 Local Geology

Subsurface geology in the immediate project area consists of the Quaternary-age Riverbank Formation. The formation is described as alluvial terrace and fan deposits. The VA Medical Center site lies immediately south of the contact between the Upper and Lower Units of the formation; the Upper unit is mapped as directly underlying the project site. This unit is described as “…Unconsolidated but compact, dark-brown to red alluvium composed of gravel, sand, silt and with minor clay.” This description is consistent with the material found in our borings.

2.2.3 Faults

A 2016 report prepared for the City of Sacramento (LSA, 2003) states, “No known active faults occur in or adjacent to the City of Sacramento. During the past 150 years, there has been no documented movement on faults mapped in Sacramento County. Nonetheless, the region has experienced numerous instances of groundshaking originating from faults in the San Andreas Fault Zone, west of the County, and the Foothills Fault System, east of the County.”

The Dunnigan Hills fault is the closest mapped fault, about 19 miles northwest of Sacramento. This fault is considered to be potentially active, with possible Holocene activity (per the USGS, within the last 15,000 years). The Green Valley-Concord Faults are the closest branches that are seismically active (within the last 200 years), located 45 miles southwest.

The fault zones within this vicinity are listed in Table 1.

Table 1. Faults Within the Site Vicinity

Fault Zone Name Proximity to Site (Surface projection in miles)

Foothills Fault System 22

Dunnigan Hills 38

Vaca 39

2.3 Subsurface Conditions

2.3.1 Soil and Bedrock

Subsurface conditions at the site were explored by advancing three borings, designated as B-1 through B-3, to depths of approximately 20 feet bgs. The borings were completed on October 8, 2016, by Woodward Drilling of Rio Vista, California, using hollow-stem auger drilling techniques. Boring logs summarizing the subsurface conditions encountered in the explorations are presented in Appendix A.

PBS has summarized the subsurface units as follows:

BARK DUST

Borings B-2 and B-3 were initiated in landscape areas. A surficial six-inch layer of bark dust was observed in each.

ASPHALT

Boring B-1 was initiated in the asphalt parking area. Asphalt was six-inches thick.

SAND FILL Red-brown poorly graded SAND fill with silt and gravel was found from 0.5 to 5.0 feet bgs in boring B-1 only.

RIVERBANK

FORMATION,

UPPER UNIT

(Qru) – CLAY

Hard, red-brown CLAY (CL) was encountered below 0.5 feet bgs in all borings. Depth to the bottom of this unit ranged from 7.5 to 8 feet bgs. Moisture contents ranged from 10 to 15 percent.

Qru – SILT

Stiff, light brown SILT (ML) was encountered between 7.5 and 10.5 feet bgs in boring B-3.

Qru – GRAVEL Dense to very dense, poorly graded GRAVEL to GRAVEL with clay (GP/GP-GM) was encountered in all borings starting between 7.5 and10 feet bgs to final depth.

Qru - SAND Medium dense to very dense, brown to red-brown, poorly graded SAND to silty SAND was found in boring B-1 between 15.5 feet and

18.8 feet bgs (total depth), and in B-3 between 15 and 19 feet bgs.

The soil types are based on visual-manual classifications using ASTM D 2488-09a guidelines. Consistency, color, relative moisture, degree of plasticity, and other distinguishing characteristics of the soil layers were noted. The terminology used in the soil classifications and other modifiers are defined and presented on the attached Table A-1 included in Appendix A.

2.3.2 Groundwater

Groundwater was not encountered during drilling to the depths explored. Please note that groundwater levels can fluctuate during the year depending on climate, irrigation season, extended periods of precipitation, drought, and other factors.

3.0 CONCLUSIONS AND RECOMMENDATIONS

3.1 Geotechnical Design Considerations

The subsurface conditions at the site consist of clay, sand, and gravel. Based on our observations and analyses, conventional foundation support on shallow spread footings is feasible for the proposed new facility. Excavation with conventional equipment is feasible over the majority of the site. However, depending on the depths of utilities and footings, some specialized equipment for ripping hard/dense soil/gravel may be necessary.

3.2 Seismic Design Criteria

The seismic design parameters, in accordance with the 2015 International Building Code (IBC), are summarized in Table 2 as follows:

Table 2. 2015 IBC Seismic Design Parameters Parameter Short Period 1 Second Maximum Credible Earthquake Spectral Acceleration Ss = 0.55 g S1 = 0.26 g

Site Class D

Site Coefficient Fa = 1.36 Fv = 1.88

Adjusted Spectral Acceleration SMS = 0.74 g SM1 = 0.49 g Design Spectral Response Acceleration Parameters SDS = 0.50 g SD1 = 0.33 g

Design Spectral Peak Ground Acceleration 0.20 g g – Acceleration due to gravity

3.2.1 Other Seismic Considerations

Other site-specific seismic hazards considered include earthquake-induced landslides, fault rupture, seiche and tsunami inundation, lateral spreading, and earthquake shaking. Based on the topography and geology at the site, we consider the risk from earthquake-induced landslides and seiche and tsunami inundation to be absent. Because the risk of liquefaction at the proposed building addition location is very low, we estimate that lateral spreading during a design-level earthquake does not represent a significant hazard. Strong earthquake ground shaking will occur during a code-based earthquake. The nearest mapped fault zones are located 20 to 30 miles from the site and the risk of fault rupture is low. Based on our current understanding of the project, our opinion is that effects of earthquake ground motions can be accounted for by using code-based design procedures.

3.3 Shallow Foundations

Shallow spread footings bearing on firm clay or sand may be used to support loads associated with the new additions, provided the recommendations in this report are followed. Footings should not be supported on undocumented fill or topsoil. We recommend the upper 6 to 12 inches (barkdust, topsoil, asphalt) be removed from the entire addition footprint, including within a 5-foot perimeter, to expose firm native clay or suitable sandy gravel fill.

3.3.1 Footing Preparation

Excavations for footings should be carefully prepared to a neat and undisturbed state. A representative from PBS should confirm suitable bearing conditions and evaluate all exposed footing subgrades. Observations should also confirm that loose or soft materials and topsoil have been removed from new footing excavations and concrete slab-on-grade areas. Localized deepening of footing excavations may be required to penetrate loose, wet, or deleterious materials. Where sand fill with gravel is exposed, we recommend this be recompacted until dense and well keyed.

We recommend a layer of compacted, crushed rock be placed over the footing subgrades to help protect them from disturbance due to foot traffic and the elements. Placement of this rock is the prerogative of the contractor; regardless, the footing subgrade should be in a dense or stiff condition prior to pouring concrete. Based on our experience, approximately 4-inches of compacted crushed rock will be suitable beneath the footings. Addition of this rock will help reduce moisture loss from the underlying clay prior to probing and footing construction.

3.3.2 Footing Embedment Depths

We recommend that all footings be founded a minimum of 18 inches below the lowest adjacent grade. The footings should be founded below an imaginary line projecting upward at a 1H:1V (horizontal to vertical) slope from the base of any adjacent, parallel utility trenches or deeper excavations.

3.3.3 Minimum Footing Widths / Design

Continuous wall and isolated spread footings should be at least 18 and 24 inches wide, respectively. Footings should be sized using a maximum allowable bearing pressure of 2,500 pounds per square foot (psf). This is a net bearing pressure and the weight of the footing and overlying backfill can be disregarded in calculating footing sizes. The recommended allowable bearing pressure applies to the total of dead plus long-term-live loads. Allowable bearing pressures may be increased by one-third for seismic and wind loads.

3.3.4 Foundation Static Settlement

Footings will settle in response to column and wall loads. Based on our evaluation of the subsurface conditions and our analysis, we estimate post-construction settlement will be less than one inch for the column and perimeter foundation loads. Differential settlement will be on the order of one-half of the total settlement.

3.3.5 Lateral Resistance

Lateral loads can be resisted by passive earth pressure on the sides and friction at the base of the footings. A passive earth pressure of 250 pounds per cubic foot (pcf) may be used for footings confined by native soils and new structural fills. The allowable passive pressure has been reduced by one-half to account for the large amount of deformation required to mobilize full passive resistance. Adjacent floor slabs, pavements, or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive resistance.

For footings supported on native soils or new structural fills, use a coefficient of friction equal to 0.30 when calculating resistance to sliding. These values do not include a factor of safety

(FS).

3.4 Floor Slabs

Satisfactory subgrade support for building floor slabs can be obtained from the native clay or sand fill subgrade prepared in accordance with our recommendations presented in the Site Preparation, Wet Weather/Wet Soil Conditions and Imported Granular Fill sections of this report.

A minimum six-inch-thick layer of imported granular material should be placed and compacted over the prepared subgrade. Imported granular material should be composed of crushed rock or crushed gravel that is relatively well graded between coarse and fine, contains no deleterious materials, has a maximum particle size of one inch, and has less than five percent by dry weight passing the US Standard No. 200 Sieve.

Floor slabs supported on a subgrade and base course prepared in accordance with the preceding recommendations, may be designed using a modulus of subgrade reaction (k) of 175 pounds per cubic inch (pci).

3.5 Ground Moisture

The perimeter ground surface and hard-scape should be sloped to drain away from all structures and away from adjacent slopes. Gutters should be tight-lined to a suitable discharge and maintained as free-flowing. The clay subgrade should not be allowed to dry significantly (refer Section 4.2.2 Dry Weather Conditions).

4.0 CONSTRUCTION RECOMMENDATIONS

4.1 Site Preparation

Construction of the proposed additions will involve clearing and grubbing of the existing vegetation or demolition of existing structures (pavement, curb, and sidewalk). Demolition should include removal of structures throughout the proposed new building footprint.

Underground utility lines or other abandoned structural elements should also be removed. The voids resulting from removal of foundations or loose soil in utility lines should be backfilled with compacted structural fill. The base of these excavations should be excavated to firm native subgrade before filling, with sides sloped at a minimum of 1H:1V, to allow for uniform compaction. As an alternative, it may be feasible to abandon utilities in place using flowable grout.

Materials generated during demolition should be transported off site or stockpiled in areas designated by the owner’s representative.

4.1.1 Proofrolling/Subgrade Verification

Following site preparation and prior to placing aggregate base for the shallow foundations, building pad, or pavement sections, the exposed subgrade should be evaluated either by proofrolling or another method of subgrade verification. The subgrade should be proofrolled with a fully loaded dump truck or similar heavy, rubber-tire construction equipment to identify unsuitable areas. If evaluation of the subgrades occur during wet conditions, or if proofrolling the subgrades will result in disturbance, they should be evaluated by PBS using a steel foundation probe. We recommend that PBS be retained to observe the proofrolling and perform the subgrade verifications. Unsuitable areas identified during the field evaluation should be compacted to a firm condition or be excavated and replaced with structural fill.

4.2 Subgrade Protection

4.2.1 Wet Weather/Wet Soil Conditions

Trafficability on the near-surface soils may be difficult during or after extended wet periods or when the moisture content of the surface soil is more than a few percentage points above optimum. Soils that have been disturbed during site preparation activities, or soft or loose zones identified during probing or proofrolling, should be removed and replaced with structural fill or compacted stabilization material.

Track-mounted excavating equipment may be required during wet weather. The thickness of the haul roads and staging areas will depend on the amount and type of construction traffic.

The material used for haul roads should be stabilization material (Section 4.5.4). A 12- to 18-inch-thick mat of stabilization material is sufficient for light staging areas. The stabilization material for haul roads and areas with repeated heavy construction traffic typically needs to be increased to between 18 to 24 inches. The actual thickness of haul roads and staging areas should be based on the Contractor’s approach to site development, the amount and type of construction traffic, and is the Contractor’s responsibility. The stabilization material should be placed in one lift over the prepared, undisturbed subgrade and compacted using a smooth-drum, non-vibratory roller. Additionally, a geotextile fabric should be placed as a barrier between the subgrade and stabilization material. The geotextile should meet the requirements of an be installed in conformance with Caltrans 88-1.02O – Subgrade Enhancement Geotextile.

4.2.2 Dry Weather Conditions

Medium plasticity clay subgrade soils remaining beneath footings, slabs, or pavements should not be allowed to get wet or dry significantly. Clay soils should be covered within 4 hours of exposure by a minimum of 4 inches of crushed rock or plastic sheeting during the dry season. Exposure of these materials should be coordinated with the geotechnical engineer so that the subgrade suitability can be evaluated prior to being covered.

4.3 Excavation

Excavation with conventional equipment is feasible over the majority of the site. However, depending on the depths of utilities and footings, some specialized equipment for ripping and breaking rock may be necessary.

For the purposes of this report, rock excavation would apply to subsurface materials that cannot be excavated with a CAT 235 excavator (or equivalent) equipped with rock teeth, and would therefore require systematic drilling and blasting or the use of a pneumatic rock hammer. The project schedule and budget should include a contingency for rock excavation and increased backfill volumes. PBS should be retained to review the grading and utility plans when they are available, for comparison with encountered field conditions.

All excavations should be made in accordance with applicable Occupational Safety and Health Administration (OSHA) and State regulations. The contractor is solely responsible for adherence to the OSHA requirements. Trench cuts should stand relatively vertical to a depth of approximately four feet bgs, provided no groundwater seepage is present in the trench walls.

Open excavation techniques may be used, provided the excavation is configured in accordance with the OSHA requirements, groundwater seepage is not present, and with the understanding that some sloughing may occur. The trenches should be flattened if sloughing occurs or seepage is present. If shallow groundwater is observed during construction, use of a trench shield or other approved temporary shoring is recommended for cuts that extend below groundwater seepage, or if vertical walls are desired for cuts deeper than four feet bgs. If dewatering is used, we recommend that the type and design of the dewatering system be the responsibility of the contractor, who is in the best position to choose systems that fit the overall plan of operation.

4.4 Permanent Slopes

Permanent cut and fill slopes up to 10 feet tall may be constructed at inclinations of up to 2H:1V.

Slopes that will be maintained by mowing should not be constructed steeper than 3H:1V. Newly constructed fill slopes should be over-built by at least 12 inches and then trimmed back to the required slope to maintain a firm face.

Access roads and pavements should be located at least 5 feet from the top of cut and fill slopes.

The setback should be increased to 10 feet for buildings, unless special foundation considerations are implemented. Slopes should be planted with appropriate vegetation to provide protection against erosion as soon as possible after grading. Surface water runoff should be collected and directed away from slopes to prevent water from running down the face of the slope.

4.5 Structural Fill

Fills should be placed over subgrade that has been prepared in conformance with the Site Preparation and Wet Weather/Wet Soil Conditions sections of this report. A wide range of material may be used as structural fill; however, all material used should be free of organic matter or other unsuitable materials and should meet the specifications provided in the Standard Specifications, State of California, Department of Transportation (Caltrans 2015) depending on the application. A brief characterization of some of the acceptable materials and our recommendations for their use as structural fill is provided below.

4.5.1 Borrow Material

Borrow material for general structural fill construction should meet the requirements set forth in Caltrans 19-7–Borrow Material. The on site clay may be used as structural fill if processed properly, but it may be difficult to dry the clay to near optimum moisture for adequate compaction. It will be necessary moisture condition site soils to within 2 percent of the optimum moisture content prior to compaction. Due to the time required to moisture condition on site soils, it may not be feasible to reuse these materials as structural fill.

When used as structural fill, on-site soils should be placed in lifts with a maximum uncompacted thickness of 6 inches and compacted to not less than 92 percent of the maximum dry density, as determined by ASTM D 1557. If suitable common borrow material is not available, use of selected general backfill, as specified in Caltrans 6-2–Material, should be considered.

4.5.2 Import Granular Material

Imported granular material used during periods of wet weather or for haul roads, building pad subgrades, staging areas, etc., should be pit or quarry run rock, crushed rock, or crushed gravel and sand and should meet the specifications provided in Caltrans 19-7– Borrow Material. However, the imported granular material should also be fairly well graded between coarse and fine material and have less than 5 percent by dry weight passing the US Standard No. 200 Sieve.

Imported granular material should be placed in lifts with a maximum uncompacted thickness of 8 to 12 inches and be compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557. During the wet season or when wet subgrade conditions exist, the initial lift should be approximately 18 inches in uncompacted thickness and should be compacted by rolling with a smooth-drum roller without using vibratory action.

Where imported granular material is placed over soft-soil subgrades, we recommend a geotextile be placed as a barrier between the subgrade and imported granular material.

Depending on site conditions, the geotextile should meet and be installed in conformance with Caltrans 88-1.02O–Subgrade Enhancement Geotextile.

4.5.3 Trench Backfill

Trench backfill placed beneath, adjacent to, and for at least 2 feet above utility lines (i.e., the pipe zone), should consist of well-graded granular material with a maximum particle size of 1½-inches and less than 10 percent by dry weight passing the US Standard No. 200 Sieve, and should meet the standards prescribed by Caltrans Division VII, Drainage for the type of pipe specified. The pipe zone backfill should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer or local building department.

Within roadway alignments or beneath building pads, the remainder of the trench backfill should consist of well-graded granular material with a maximum particle size of 1½-inches, less than 10 percent by dry weight passing the US Standard No. 200 Sieve, and should meet the requirements for specific surface loading or other criteria of the backfill zone. This material should be compacted to at least 92 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer or local building department. The upper 2 feet of the trench backfill should be compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 1557.

Outside of structural improvement areas (e.g., roadway alignments or building pads), trench backfill placed above the pipe zone may consist of general fill materials that are free of organics and materials over 6-inches in diameter and meet Caltrans 19-7–Borrow Material.

This general trench backfill should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D 1557, or as required by the pipe manufacturer or local building department.

4.5.4 Stabilization Material

Stabilization rock should consist of imported granular material that is well-graded, angular, crushed rock consisting of 4- or 6-inch-minus material with less than 2 percent passing the US Standard No. 4 Sieve. The material should be free of organic matter and other deleterious material.

4.5.5 Retaining Wall Drain Backfill

Backfill in a 2-foot zone against the back of retaining walls and for subsurface trench drains should consist of granular drain rock meeting the specifications provided in Caltrans 19- 3.02C–Pervious Backfill Material. The granular drain rock should be wrapped in a geotextile fabric that meets the specifications provided in Caltrans 88-1.02B–Filter Fabric.

4.5.6 Footing and Floor Slab Base Course

Imported granular material placed at the base of retaining walls, building footings, and floor slabs should be clean, crushed rock or crushed gravel, and sand that is fairly well-graded between coarse and fine. The granular materials should contain no deleterious material and have a maximum particle size of 1½-inches. The imported granular material should be placed in one lift and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557.

4.5.7 Aggregate Base Course

Imported granular material used as aggregate base course (base rock) along roadway alignments should be clean, crushed rock or crushed gravel, and sand that is fairly well-graded between coarse and fine. The base aggregate should meet the gradation defined in Caltrans 26–Aggregate Bases, depending upon application. The base aggregate should be compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D 1557.

5.0 ADDITIONAL SERVICES AND CONSTRUCTION OBSERVATIONS

In most cases, other services beyond completion of a geotechnical engineering report are necessary or desirable to complete the project. Occasionally, conditions or circumstances arise that require the performance of additional work that was not anticipated when the geotechnical report was written. PBS offers a range of environmental, geological, geotechnical, and construction services to suit the varying needs of our clients.

PBS should be retained to review the plans and specifications for this project before they are finalized. Such a review allows us to verify that our recommendations and concerns have been adequately addressed in the design.

Satisfactory earthwork performance depends on the quality of construction. Sufficient observation of the contractor's activities is a key part of determining that the work is completed in accordance with the construction drawings and specifications. We recommend that PBS be retained to observe general excavation, stripping, fill placement, and footing and pavement subgrades. Subsurface conditions observed during construction should be compared with those encountered during the subsurface explorations. Recognition of changed conditions requires experience; therefore, qualified personnel should visit the site with sufficient frequency to detect whether subsurface conditions change significantly from those anticipated.

6.0 LIMITATIONS

This report has been prepared for the exclusive use of the addressee (Client), and their architects and engineers, for aiding in the design and construction of the proposed development and is not to be relied upon by other parties. It is not to be photographed, photocopied, or similarly reproduced, in total or in part, without express written consent of the Client and PBS. It is the addressee's responsibility to provide this report to the appropriate design professionals, building officials, and contractors to ensure correct implementation of the recommendations.

The opinions, comments, and conclusions presented in this report are based upon information derived from our literature review, field explorations, laboratory testing, and engineering analyses. It is possible that soil, rock, or groundwater conditions could vary between or beyond the points explored. If soil, rock, or groundwater conditions are encountered during construction that differ from those described herein, the Client is responsible for ensuring that PBS is notified immediately so that we may reevaluate the recommendations of this report.

Unanticipated fill, soil and rock conditions, and seasonal soil moisture and groundwater variations are commonly encountered and cannot be fully determined by merely taking soil samples from soil borings. Such variations may result in changes to our recommendations and may require additional funds for expenses to attain a properly constructed project. Therefore, we recommend a contingency fund to accommodate such potential extra costs.

The scope of services for this subsurface exploration and geotechnical report did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the soil, surface water, or groundwater at this site.

If there is a substantial lapse of time between the submission of this report and the start of work at the site, if conditions have changed due to natural causes or construction operations at or adjacent to the site, or if the basic project scheme is significantly modified from that assumed, this report should be reviewed to determine the applicability of the conclusions and recommendations presented herein. Land use, site conditions (both on and off site), or other factors may change over time and could materially affect our findings. Therefore, this report should not be relied upon after three years from its issue, or in the event that the site conditions change.

7.0 REFERENCES

ASCE (American Society of Civil Engineers). (2010). Minimum Design Loads for Buildings and

Other Structures, ASCE/SEI 07-10.

California Geological Survey Note 36,: (2002), California Department of Conservation

Caltrans (2015). Standard Specifications, State of California, Business, Transportation, and Housing Agency, Department of Transportation.

IBC. (2015). International Building Code. Country Club Hills, IL: International Code Council, Inc.

FIGURES

BD-2

BD-1

BD-3

SITE PLAN

FIGURE

PROJECT #

DATE

L:

\P ro je ct s\

0\

0-

9\

2_

V A

M at he rD er m at ol og y\

G eo te ch

\D W

G \7

.0

_F

IG

-2

.d w g N ov

2, :4

3a m j im b

SOURCE: © 2016 GOOGLE EARTH PRO.

SCALE: 1" = 30'

0' 15' 30' 60'

VA MEDICAL CENTER - DERMATOLOGY OUTPATIENT SERVICES

MATHER, CALIFORNIA

PREPARED FOR: K.F. DAVIS ENGINEERING, INC

73222.000

DEC 2016

BD-1 BORING NUMBER AND APPROXIMATE LOCATION

LEGEND

SUBJECT PROPERTY

VICINITY MAP

VA MEDICAL CENTER - DERMATOLOGY OUTPATIENT SERVICES

MATHER, CALIFORNIA

SCALE: 1" = 2,000'

PREPARED FOR: K.F. DAVIS ENGINEERING, INC

FIGURE

73222.000

PROJECT #

DEC 2016

DATE

L:

\P ro je ct s\

0\

0-

9\

2_

V A

M at he rD er m at ol og y\

G eo te ch

\D W

G \7

.0

_F

IG

-2

.d w g N ov

2, :4

2a m j im b

PROJECT LOCATION

0' 1,000' 2,000' 4,000'

LOS ANGELES

SACRAMENTO

SITE

CALIFORNIA

SOURCE: USGS CARMICHAEL CA QUADRANGLE 1992.

APPENDIX A

Field Explorations

A-1

APPENDIX A – FIELD EXPLORATIONS

A1.0 GENERAL

PBS explored the subsurface conditions at the project site by advancing three borings to depths of up to 20.4 feet bgs. The approximate locations of the explorations are shown on Figure 2, Site Plan.

The procedures and techniques used to drill the borings, collect samples, and other field techniques, are described in detail in the following paragraphs. Unless otherwise noted, all soil sampling and classification procedures followed local engineering practices that are in general accordance with relevant ASTM procedures. “General accordance” means that certain local and common drilling and descriptive practices and methodologies have been followed.

A2.0 BORINGS

A2.1 Drilling Borings were advanced with a truck-mounted BK-81 drill rig provided and operated by Woodward Drilling Co., Inc., of Rio Vista, California, using hollow-stem auger drilling techniques.

The borings were observed by an engineering geologist from PBS, who maintained a detailed log of the subsurface conditions and materials encountered during the course of the work.

A2.2 Sampling Disturbed soil samples were taken in the borings at selected depth intervals. The samples were obtained using a standard 2-inch and 3-inch outside diameter (OD), split-spoon sampler following procedures prescribed for the standard penetration test (SPT). Using the SPT, the sampler is driven 18 inches into the soil using a 140-pound hammer dropped 30 inches. The number of blows required to drive the sampler the last 12 inches is defined as the standard penetration resistance (N-value). The N-value provides a measure of the relative density of granular soils such as sands and gravels, and the consistency of cohesive soils such as clays and plastic silts. The disturbed soil samples were examined by a member of the PBS geotechnical staff, and then sealed in plastic bags for further examination and physical testing in our laboratory.

A2.3 Boring Logs The boring logs show the various types of materials that were encountered in the boring and the depths where the materials and/or characteristics of these materials changed, although the changes may be gradual. Where material types and descriptions changed between samples, the contacts were interpreted. The types of samples taken during drilling, along with their sample identification number, are shown to the right of the classification of materials. The N-values and natural water (moisture) contents are shown further to the right.

A4.0 MATERIAL DESCRIPTION

Initially, soil samples were classified visually in the field. Consistency, color, relative moisture, degree of plasticity, and other distinguishing characteristics of the soil samples were noted.

Afterward, the samples were reexamined in the PBS laboratory, various standard classification tests were conducted, and the field classifications were modified where necessary. The terminology used in the soil classifications and other modifiers are defined in Appendix A, Table A-1, Terminology Used to Describe Soil.

Table A-1

Terminology Used to Describe Soil

Soil Descriptions

Soils exist in mixtures with varying proportions of components. The predominant soil, i.e., greater than 50 percent based upon total dry weight, is the primary soil type and is capitalized in our log descriptions, e.g., SAND, GRAVEL, SILT or CLAY. Lesser percentages of other constituents in the soil mixture are indicated by use of modifier words in general accordance with the Visual-Manual Procedure (ASTM D2488-06). “General Accordance” means that certain local and common descriptive practices have been followed. In accordance with ASTM D2488-06, group symbols (such as GP or CH) are applied on that portion of the soil passing the 3-inch (75mm) sieve based upon visual examination.

The following describes the use of soil names and modifying terms used to describe fine- and coarse-grained soils.

Fine - Grained Soils (More than 50% fines passing 0.075 mm, #200 sieve) The primary soil type, i.e. SILT or CLAY is designated through visual – manual procedures to evaluate soil toughness, dilatency, dry strength, and plasticity. The following describes the terminology used to describe fine - grained soils, and varies from ASTM 2488 terminology in the use of some common terms.

Primary soil NAME, adjective and symbols Plasticity Description

Plasticity Index (PI)

SILT

ML & MH

CLAY

CL & CH

ORGANIC

SILT & CLAY

OL & OH

SILT Organic SILT Non-plastic 0 - 3 SILT Organic SILT Low plasticity 4 - 10

SILT / Elastic

SILT

Lean CLAY Organic clayey SILT Medium Plasticity 10 – 20

Elastic SILT Lean/Fat CLAY Organic silty CLAY High Plasticity 20 – 40 Elastic SILT Fat CLAY Organic CLAY Very Plastic >40

Modifying terms describing secondary constituents, estimated to 5 percent increments, are applied as follows:

Description % Composition With sand; with gravel

(combined total greater than 15% but less than 30%, modifier is whichever is greater)

15% to 25%

Sandy; or gravelly (combined total greater than 30% but less than

50%, modifier is whichever is greater) 30% to 50%

Borderline Symbols, for example CH/MH, are used where soils are not distinctly in one category or where variable soil units contain more than one soil type. Dual Symbols, for example CL-ML, are used where two symbols are required in accordance with ASTM D2488.

Soil Consistency. Consistency terms are applied to fine-grained, plastic soils (i.e., PI > 7). Descriptive terms are based on direct measure or correlation to the Standard Penetration Test N-value as determined by ASTM D1586- 84, as follows. Note, SILT soils with low to non-plastic behavior (i.e. PI < 7) are classified using relative density.

Consistency Term SPT N-value Unconfined Compressive Strength tsf kPa Very soft Less than 2 Less than 0.25 Less than 24

Soft 2 – 4 0.25 - 0.5 24 - 48 Medium stiff 5 – 8 0.5 - 1.0 48 – 96

Stiff 9 – 15 1.0 - 2.0 96 – 192 Very stiff 16 – 30 2.0 - 4.0 192 – 383

Hard Over 30 Over 4.0 Over 383

Table A-1

Terminology Used to Describe Soil

Soil Descriptions

Coarse - Grained Soils (less than 50% fines) Coarse-grained soil descriptions, i.e., SAND or GRAVEL, are based on that portion of materials passing a 3-inch (75mm) sieve. Coarse-grained soil group symbols are applied in accordance with ASTM D2488-06 based upon the degree of grading, or distribution of grain sizes of the soil. For example, well graded sand containing a wide range of grain sizes is designated SW; poorly graded gravel, GP, contains high percentages of only certain grain sizes. Terms applied to grain sizes follow.

Material Particle Diameter Inches Millimeters

Sand (S) 0.003 - 0.19 0.075 - 4.8 Gravel (G) 0.19 - 3.0 4.8 - 75

Additional Constituents Cobble 3.0 - 12 75 - 300 Boulder 12 - 120 300 - 3050

The primary soil type is capitalized, and the amount of fines in the soil are described as indicated by the following examples. Other soil mixtures will provide similar descriptive names.

Example: Coarse-Grained Soil Descriptions with Fines

5% to less than 15% fines (Dual Symbols)

15% to less than 50% fines

GRAVEL with silt, GW-GM Silty GRAVEL: GM SAND with clay, SP-SC Silty SAND: SM

Additional descriptive terminology applied to coarse-grained soils follow.

Example: Coarse-Grained Soil Descriptions with Other Coarse-Grained Constituents

Coarse-Grained Soil Containing Secondary Constituents

With sand or with gravel > 15% sand or gravel With cobbles; with boulders Any amount of cobbles or boulders.

Cobble and boulder deposits may include a description of the matrix soils, as defined above.

Relative Density terms are applied to granular, non-plastic soils based on direct measure or correlation to the Standard Penetration Test N-value as determined by ASTM D1586-84.

Relative Density Term SPT N-value Very loose 0 - 4

Loose 5 - 10 Medium dense 11 - 30

Dense 31 - 50 Very dense > 50

Key To Test Pit and Boring Log Symbols

SAMPLING DESCRIPTIONS1

SP

T

Dr ive

Sa m pl er

St an da rd

Pe ne tra tio n Te st

AS

TM

D

Sh el by

Tu be

Pu sh

Sa m pl er

AS

TM

D

Sp ec ia liz ed Dr ive Sa m pl er s

(D et ai ls

No te d on

Lo gs

Sp ec ia liz ed

Dr ill or Pu sh

Sa m pl er

(D et ai ls

No te d on

Lo gs

G ra b Sa m pl e

Ro ck

Co rin g In te rv al Sc re en

(W at er or

Ai r S am pl in g)

W at er Le ve l D ur in g

Dr illi ng /E xc av at io n W at er

Le ve l A fte r Dr illi ng

/E xc av at io n

LOG GRAPHICS

Geotechnical Testing/Acronym Explanations noitadarG eveiSVEIS retemorteneP tekcoPPP ytisneD yrDDD stimiL grebrettATTA retemorteneP enoC cimanyDPCD oitaR gniraeB ainrofilaCRBC tnetnoC cinagrOCO enavroTROT suludoM tneiliseRSER noitadilosnoCNOC raehS enaVSV raehS tceriDSD

P200 Percent Passing U.S. Standard No. 200 Sieve htgnertS evisserpmoC denifnocnUCU timiL yticitsalPLP ecafrus dnuorg woleBsgb xednI yticitsalPIP leveL aeS naeMLSM timiL diuqiLLL

HYD Hydrometer Gradation

1Note: Details of soil and rock classification systems are available on request. Rev. 02/23/15

Lithology Boundary -separates distinct units (i.e. Fill, Alluvium, Bedrock Fm) (at approx.

depth indicated)

Soil-Type or Material-Type Change Boundary - separates changes in soil-type and material-type within the same litholgic unit (at approx.

depth indicated)

Sampler Type

Sample Recovery Sample

Interval

Instrumentation Detail Sampling SymbolsSoil and Rock

Well Pipe

Piezometer

Piezometer

Ground Surface

Well Cap

Bottom of Hole

So il or R oc k

Ty pe s

Well Seal

Well Screen

0.0

0.5

5.0

7.5

10.0

15.5

18.8

LL = 28

PL = 15

PI = 13

Used 3-inch split-spoon sampler

BARK DUST

Red-brown poorly graded SAND (SP-SM) with silt and gravel; low plasticity; fine sand; fine, subrounded gravel; moist

FILL

Very stiff red-brown CLAY (CL); medium plasticity; moist

Dense brown poorly graded GRAVEL (GP-GC) with clay; non-plastic; fine to coarse, subrounded gravel; moist

Very dense light gray poorly graded GRAVEL (GP); fine to coarse, subrounded gravel; dry

Very dense red-brown poorly graded SAND (SP); fine sand; moist

Final depth 18.8 feet bgs due to refusal in gravel; boring backfilled with bentonite.

Groundwater not encountered at time of exploration.

ATT

D E

P T

H INSTALLATION AND

COMMENTS

0 50 100

CORE REC%RQD%

MOISTURE CONTENT %

DYNAMIC CONE

PENETROMETER

UNCORRECTED N-VALUE

B

O R

IN

G

L O

G

2.

0_

_R G

.G P

J P

B S

_D A

T A

T M

P L_

G E

O .G

D T

P R

IN

T

D A

T E

/1 2/

:R

W

G R

A P

H

IC

LO

G

DRILLED BY: Woodward Drilling Company, Inc.

LOGGED BY: B. Portwood

DRILLING METHOD: Hollow-Stem Auger

MATERIAL DESCRIPTION

S A

M P

LE

T

Y

E

S A

M P

LE

ID

BORING B-1

T E

S T

IN

G

DEPTH

FEET

4412 SW Corbett Avenue Portland, Oregon 97239 Phone: 503.248.1939 Fax: 866.727.0140 (See Site Plan)

APPROX. BORING B-1 LOCATION:

FIGURE A1

LOGGING COMPLETED: 10/08/16

HAMMER EFFICIENCY PERCENT:

BIT DIAMETER: 8 inches

VA MEDICAL CENTER - DERMATOLOGY SERVICES

MATHER, CALIFORNIA

PBS PROJECT NUMBER:

73222.000

NOTE: Lines representing the interface between soil/rock units of differing description are approximate only, inferred where between samples, and may indicate gradual transition.

Surface Conditions: Planter- Bark Dust

28-50/6

21-50/4

50/4

S -1

S -2

S -3

S -4

S -5

S -6

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

0 50 100

8.0

10.0

15.0

19.5

20.4

Used 3-inch split-spoon sampler

Used 3-inch split-spoon sampler

Used 3-inch split-spoon sampler

ASPHALT

Very stiff to hard red-brown CLAY (CL);

medium plasticity; moist

Very dense brown poorly graded GRAVEL (GP); fine to coarse, subrounded gravel; dry

Dense brown poorly graded GRAVEL (GP-GC) with clay; non-plastic; fine to coarse, subrounded gravel; moist

Dense light gray poorly graded GRAVEL (GP) with cobbles; coarse, subrounded gravel;

subrounded cobbles; dry

Dense light gray poorly graded GRAVEL (GP-GM) with silt and cobbles; non-plastic; fine to coarse, subrounded gravel; subrounded cobbles; dry Final depth 20.4 feet bgs due to refusal in gravel; boring backfilled with bentonite.

Groundwater not encountered at time of exploration.

D E

P T

H INSTALLATION AND

COMMENTS

0 50 100

CORE REC%RQD%

MOISTURE CONTENT %

DYNAMIC CONE

PENETROMETER

UNCORRECTED N-VALUE

B

O R

IN

G

L

2.

0_

_R G

.G P

J P

B S

_D A

T A

T M

P L_

G E

O .G

IN

T

D A

T E

/1 2/

:R

W

G R

A P

H

IC

LO

G

DRILLED BY: Woodward Drilling Company, Inc.

LOGGED BY: B. Portwood

DRILLING METHOD: Hollow-Stem Auger

MATERIAL DESCRIPTION

S A

M P

LE

T

Y

M P

LE

ID

BORING B-2

T E

S T

IN

G

DEPTH

FEET

4412 SW Corbett Avenue Portland, Oregon 97239 Phone: 503.248.1939 Fax: 866.727.0140 (See Site Plan)

APPROX. BORING B-2 LOCATION:

FIGURE A2

LOGGING COMPLETED: 10/08/16

HAMMER EFFICIENCY PERCENT:

BIT DIAMETER: 8 inches

VA MEDICAL CENTER - DERMATOLOGY SERVICES

MATHER, CALIFORNIA

PBS PROJECT NUMBER:

73222.000

NOTE: Lines representing the interface between soil/rock units of differing description are approximate only, inferred where between samples, and may indicate gradual transition.

Surface Conditions: Asphalt

36-50/5

34-50/5

S -1

S -2

S -3

S -4

S -5

S -6

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

0 50 100

7.5

10.5

15.0

19.0

19.5

P200 = 73%

P200 = 23%

BARK DUST

Very stiff to hard red-brown CLAY (CL) with sand; medium plasticity; fine to medium sand;

moist

Stiff light brown SILT (ML) with sand; low plasticity; fine to coarse sand; dry becomes very stiff Very dense light gray poorly graded GRAVEL (GP); fine to coarse, subrounded gravel; dry

Medium dense brown silty SAND (SM);

non-plastic; fine to coarse sand; moist

Very dense light gray poorly graded GRAVEL (GP); fine to coarse, subrounded gravel; dry Final depth 19.5 feet bgs due to refusal in gravel; boring backfilled with bentonite.

Groundwater not encountered at time of exploration.

P200

P200

D E

P T

H INSTALLATION AND

COMMENTS

0 50 100

CORE REC%RQD%

MOISTURE CONTENT %

DYNAMIC CONE

PENETROMETER

UNCORRECTED N-VALUE

B

O R

IN

G

L

2.

0_

_R G

.G P

J P

B S

_D A

T A

T M

P L_

G E

O .G

IN

T

D A

T E

/1 2/

:R

W

G R

A P

H

IC

LO

G

DRILLED BY: Woodward Drilling Company, Inc.

LOGGED BY: B. Portwood

DRILLING METHOD: Hollow-Stem Auger

MATERIAL DESCRIPTION

S A

M P

LE

T

Y

M P

LE

ID

BORING B-3

T E

S T

IN

G

DEPTH

FEET

4412 SW Corbett Avenue Portland, Oregon 97239 Phone: 503.248.1939 Fax: 866.727.0140 (See Site Plan)

APPROX. BORING B-3 LOCATION:

FIGURE A3

LOGGING COMPLETED: 10/08/16

HAMMER EFFICIENCY PERCENT:

BIT DIAMETER: 8 inches

VA MEDICAL CENTER - DERMATOLOGY SERVICES

MATHER, CALIFORNIA

PBS PROJECT NUMBER:

73222.000

NOTE: Lines representing the interface between soil/rock units of differing description are approximate only, inferred where between samples, and may indicate gradual transition.

Surface Conditions: Planter- Bark Dust

50/4.5

S -1

S -2

S -3

S -4

S -5

S -6

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

0 50 100

APPENDIX B

Laboratory Testing

B-1

APPENDIX B – LABORATORY TESTING

B1.0 GENERAL

Samples obtained during the field explorations were examined in the PBS laboratory. The physical characteristics of the samples were noted and the field classifications were modified where…