Geotechnical Evaluation Cajon Air Center at Gillespie Field El Cajon, California

GEOTECHNICAL EVALUATION CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA

PREPARED FOR: Kimley-Horn and Associates, Inc. 401 B Street, Suite 600 San Diego, California 92101

PREPARED BY: Ninyo & Moore Geotechnical and Environmental Sciences Consultants 5710 Ruffin Road San Diego, California 92123

May 11, 2016 Project No. 108139001

Cajon Air Center at Gillespie Field May 11, 2016 El Cajon, California Project No. 108139001

TABLE OF CONTENTS Page 1. INTRODUCTION ...... 1 2. SCOPE OF SERVICES ...... 1 3. SITE DESCRIPTION ...... 3 4. PROJECT DESCRIPTION ...... 4 5. SUBSURFACE EXPLORATION ...... 4 5.1. Percolation Testing ...... 5 6. GEOTECHNICAL LABORATORY TESTING ...... 6 7. GEOLOGY AND SUBSURFACE CONDITIONS ...... 7 7.1. Regional Geologic Setting ...... 7 7.2. Site Geology ...... 8 7.2.1. Fill ...... 8 7.2.2. Alluvium ...... 8 7.2.3. Granitic Rock ...... 9 7.3. Groundwater ...... 9 7.4. Flood Hazards ...... 10 8. GEOLOGIC HAZARDS ...... 10 8.1. Faulting and Seismicity ...... 10 8.2. Ground Rupture ...... 11 8.3. Strong Ground Motion ...... 11 8.4. Liquefaction and Seismically Induced Settlement ...... 12 8.5. Landsliding ...... 12 9. CONCLUSIONS ...... 12 10. RECOMMENDATIONS ...... 13 10.1. Earthwork ...... 14 10.1.1. Site Preparation ...... 14 10.1.2. Excavation Characteristics ...... 14 10.1.3. Excavation Bottom Characteristics ...... 15 10.1.4. Temporary Excavations ...... 15 10.1.5. Construction Dewatering ...... 16 10.1.6. Remedial Grading ...... 16 10.1.7. Materials for Fill ...... 17 10.1.8. General Compacted Fill ...... 18 10.1.9. Subgrade Compaction – Airfield Pavements ...... 20 10.1.10. Subgrade Preparation – Hydromodification Vault ...... 21 10.1.11. Lateral Pressures for Thrust Blocks ...... 21 10.1.12. Pipe Bedding and Modulus of Soil Reaction (E') ...... 21 10.1.13. Pipe Zone Backfill ...... 22 10.1.14. Utility Trench Zone Backfill ...... 22

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10.1.15. Drainage ...... 23 10.2. Seismic Design Considerations ...... 24 10.3. Underground Structures ...... 24 10.3.1. Mat Foundations ...... 24 10.3.2. Lateral Pressures ...... 25 10.3.3. Uplift Considerations ...... 26 10.3.4. Static Settlement ...... 27 10.4. Concrete Flatwork ...... 27 10.5. Corrosion ...... 27 10.6. Concrete ...... 28 10.7. Pre-Construction Conference ...... 28 10.8. Plan Review and Construction Observation ...... 28 11. LIMITATIONS ...... 29 12. REFERENCES ...... 31

Tables Table 1 – Percolation Test Results ...... 6 Table 2 – 2013 California Building Code Seismic Design Criteria ...... 24

Figures Figure 1 – Site Location Figure 2 – Exploration Locations Figure 3 – Fault Locations Figure 4 – Geology Figure 5 – Thrust Block Lateral Earth Pressure Diagram Figure 6 – Lateral Earth Pressures for Underground Structures Figure 7 – Uplift Resistance Diagram for Underground Structures

Appendices Appendix A – Excavation Logs Appendix B – Geotechnical Laboratory Testing

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1. INTRODUCTION In accordance with your request and our proposal dated March 23, 2016, we have performed an additional geotechnical evaluation for the proposed Cajon Air Center at Gillespie Field project in El Cajon, California (Figure 1). We previously prepared a draft geotechnical evaluation report for the proposed project in 2009 (Ninyo & Moore, 2009). The purpose of this study was to update, supplement, and finalize the initial draft report. This report presents data from our previous and recent background, field, and laboratory evaluations, as well as our conclusions regarding the geotechnical conditions at the subject site and our recommendations for the design and construction of the proposed airfield improvements. Additionally, the recent phase of this study was focused on providing supplemental geotechnical information regarding the hydromodification vault to be constructed at the northwest corner of the project site.

2. SCOPE OF SERVICES The scope of our geotechnical services for this project was conducted in two phases. The first phase of work was performed in 2009 and the second phase of work was performed recently, in 2016. The scope of services associated with the 2009 phase of work included the following:

 Reviewing readily available background materials pertaining to the project including previous geotechnical and environmental evaluations, geologic maps, topographic maps, and in- house information.

 Performing a geotechnical reconnaissance of the site to observe the existing conditions.

 Marking the subsurface exploration locations for utility clearance by Underground Service Alert (USA).

 Retaining a geophysical subcontractor to assist in clearing the locations of the subsurface explorations for conflicts with existing underground utilities.

 Acquiring boring permit #LMON106263 from the County of San Diego Department of En- vironmental Health (DEH) prior to the performance of our subsurface exploration.

 Coordinating with personnel from the County of San Diego to obtain access to the site for performance of our 2009 subsurface exploration.

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 Drilling, sampling, and logging 30 small-diameter exploratory borings using a truck- mounted drill rig. The borings were advanced to depths of approximately 3 to 21 feet below the existing grades. Collected soil samples were brought to our in-house geotechnical laboratory for testing and analysis.

 Performing five percolation tests in boreholes at locations selected by the project civil engineer to depths of up to approximately 6 feet. The purpose of the percolation tests was to evaluate the infiltration characteristics of the on-site soils.

 Performing geotechnical laboratory testing of representative soil samples to evaluate design parameters for the project.

 Preparing a draft report (Ninyo & Moore, 2009) presenting the results of our evaluations including conclusions and recommendations regarding the geotechnical aspects of design and construction of the proposed airfield improvements.

The scope of services associated with of recent, 2016 phase of work included the following:

 Reviewing background information including the draft geotechnical report (Ninyo & Moore, 2009) and other available pertinent geotechnical and environmental data and reports, geologic maps, topographic maps, and in-house information.

 Performing a field reconnaissance to observe site locations and to mark the exploration locations for clearance by USA.

 Acquiring boring permit LMWP-002214 from the County of San Diego DEH prior to the performance of the second phase of our subsurface exploration.

 Drilling, logging, and sampling of three small-diameter exploratory borings with a truck- mounted drill rig. The borings were drilled to depths of up to approximately 21½ feet. Rela- tively undisturbed drive and bulk soils samples of the materials encountered were collected at selected intervals and transported to our in-house geotechnical laboratory for testing.

 Excavating and logging one exploratory test trench to a depth of approximately 12 feet using a backhoe.

 Performing laboratory testing on representative soil samples to evaluate design parameters and soil characteristics.

 Compiling and performing engineering analysis of the data obtained from our previous and recent background review, field activities, and geotechnical laboratory testing.

 Preparing this report presenting our findings, conclusions, and geotechnical recommendations for the design and construction of the proposed project.

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3. SITE DESCRIPTION The project site is located within the southeastern portion of Gillespie Field Airport in El Cajon, California. The approximately 70-acre site is generally bounded by Airport Drive on the north, Joe Crosson Drive on the west, West Bradley Avenue and Floyd Smith Drive on the south, and Wing Avenue on the east (Figure 1). An unnamed tributary of the nearby Forester Creek is in an open, graded drainage channel along the southern end of the project site. Gillespie Field is a general aviation airport serving the San Diego County area. Gillespie Field is owned and operated by the County of San Diego Department of Public Works, County Airports group.

The site is currently occupied by an asphalt concrete (AC) parking lot in the southwest portion of the site. Further existing improvements at the site include perimeter fencing and some concrete access driveways and rock rip-rap associated with the drainage channel along the southern end of the project site. Other areas of the site are generally vacant and undeveloped and are covered with low-lying grasses. Previous uses of the site included the Cajon Speedway racetrack, a motocross track, a scrap yard, staging areas for nearby waste haulers and automobile dealers and other businesses, and a golf driving range. The structures associated with past use of the site have since been demolished. However, an easement for underground waterlines crosses the site in a generally northeasterly direction. Other utilities known to be present include an east-west trending sewer line in the northern part of the site and east-west directed overhead power lines extending through the central section of the site.

Various wells have been constructed at the site, including an irrigation supply well and groundwater monitoring wells. The irrigation supply well was found in the southern portion of the site during a Ninyo & Moore site assessment (Ninyo & Moore, 2005a). The well was reportedly used for irrigation of the golf driving range and for track condition maintenance at the motocross track on the northern portion of the site. The six groundwater monitoring wells onsite have been peri- odically monitored since approximately 1998 (Ametek, 2016). During our site reconnaissance in 2009, standing water was observed in the northern portion of the site.

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4. PROJECT DESCRIPTION Based on our review of project plans (Kimley-Horn, 2016), we understand that the proposed project will extend the Gillespie Field facilities with the addition of two new main Taxilanes N and S, six cross taxilanes (N1 through N6), a transient apron, a transient ramp, and ten subdivided lots that will be sheet graded for future airport-related developments. The taxilanes will be paved with AC and the transient ramp and aprons will be AC or concrete paved. Further improvements to the site will include the installation of underground utility mains to support the new subdivided lots and the construction of various bioretention/biofiltration basins between the taxilanes and cross taxilanes. These basins will connect to a new subterranean hydromodification vault to be constructed at the northwest corner of the site, as shown on Figure 2. The vault will be approximately 300 feet wide by 350 feet long and will extend to a depth of approximately 11 feet below the finished surface. As part of these site improvements, we anticipate that grading of the site will consist of performing cuts and fills on the order of a few feet.

Also, as part of the site development, several off-site improvements will be made to the adjoining roadways. In addition to repaving portions of Joe Crosson Drive and Wing Avenue, concrete curbs-and-gutters and sidewalks will be constructed. New storm drain improvements will also be added to the roadways.

As requested, our work was focused on assessing the geotechnical conditions at the site through geotechnical field and laboratory analyses. Our scope of services did not include developing pavement design recommendations for the airport pavements for the taxiways, cross taxiways, aprons, and ramps. This study did not evaluate pavement sections for non-airfield applications (i.e., access roads or driveways that may be built for future facilities in the subdivided parcels).

5. SUBSURFACE EXPLORATION As discussed, we previously performed the first phase of our subsurface exploration at the site in 2009. As part of the previous phase of work, 30 small-diameter borings were drilled from Febru- ary 25 through February 27, 2009, five of which were used for infiltration/percolation testing (PT-1 through PT-5). Prior to drilling, these boring locations were cleared of underground utili-

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ties by participating members of Underground Service Alert (USA) and a utility locating subcontractor. The borings were drilled to depths of approximately 3 to 21 feet using a truck-mounted drill rig. During the field operations, the borings and test pit were logged and sampled by Ninyo & Moore personnel. Representative bulk and in-place soil samples were obtained from the subsurface explorations and transported to our in-house geotechnical laboratory for testing. The approximate locations of the borings (B-1 through B-25) and infiltration/percolation tests testing (PT-1 through PT-5) are shown on Figure 2. Logs of the borings and infiltration/percolation tests are included in Appendix A.

Our recent, second phase of the subsurface exploration was conducted on April 5, 2016 and consisted of drilling, logging, and sampling three small-diameter borings (NM-1 through NM-3) and one exploratory test trench (TP-1). These explorations were specifically performed to focus on the geotechnical subsurface conditions at the location of the hydromodification vault. Prior to drilling and excavating, the boring and test trench locations were cleared of underground utilities by participating members of USA. The borings were drilled to depths up to approximately 21½ feet using a truck-mounted drill rig equipped with 8-inch diameter, hollow-stem and solid- stem augers and manual drilling equipment. The exploratory test trench was excavated using a backhoe to a depth of approximately 12 feet. During the field operations, the borings and test trench were logged and sampled by Ninyo & Moore personnel. Representative bulk and in-place soil samples were obtained from the subsurface explorations and transported to our in-house geotechnical laboratory for testing. The approximate locations of the borings and test trench are shown on Figure 2. Logs of the borings and test trench are included in Appendix A.

5.1. Percolation Testing As a means of evaluating the infiltration characteristics of the near-surface materials, percolation testing was performed at five locations during the initial phase of our subsurface exploration on February 25 and February 26, 2009 (Figure 2). The procedure used was in general accordance with the County of San Diego Department of Environmental Health De- sign Manual guidelines. Five borings (PT-1 through PT-5) were used to perform tests of near surface soils and to provide parameters for design of storm water structures. Free-draining

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pea gravel was placed at the bottom of each borehole. Varying lengths of 2-inch-diameter slotted pipe was installed in an upright position on top of the gravel layer, and the annular space was backfilled with additional gravel. Presoaking was performed by filling each test hole with approximately 12 inches of clean water. This water level was maintained for four hours and then allowed to drop overnight.

Field infiltration testing was conducted the following day after the initial presoaking. The presoak procedure was again employed for one hour on the second day. As some water re- mained overnight in the test holes following the presoak period, Case I or Case III were used for the tests. For the Case I test, the water level within the test hole was adjusted to 6 inches and two readings were taken at 30-minute intervals. The slower of the two readings was used to calculate the reported percolation rate. For the Case III test, the water depth was again adjusted to 6 inches above the gravel and testing was performed for an additional four hours with readings taken every 30 minutes. The drop that occurred during the last 30 minutes of testing was used to calculate the percolation rate in minutes per inch (mpi) for each location. Percolation rates are shown in Table 1 below.

Table 1 – Percolation Test Results Test Depth of Test Earth Unit Evaluated Adjusted Percolation Rate Location (feet) (Soil Classification) (mpi) PT-1 6 Alluvium (SM) DNP PT-2 3 Alluvium (SM) 267.9 PT-3 3 Alluvium (SM) 178.6 PT-4 6 Granitic Rock DNP PT-5 6 Granitic Rock DNP Note: DNP - did not percolate

6. GEOTECHNICAL LABORATORY TESTING Geotechnical laboratory testing was performed on representative soil samples collected during both phases of our subsurface exploration. Testing included an evaluation of in-situ dry density and moisture content, gradation characteristics, percentage of particles finer than the No. 200 sieve, Atterberg Limits, shear strength, expansion index, California bearing ratio (CBR), and soil corrosivity (including pH, electrical resistivity, chloride content, and sulfate content). Following

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the guidelines of the Federal Aviation Administration ([FAA], 2009), efforts were made to perform CBR tests using the three point method for each soil type encountered and sampled during our subsurface exploration. The results of the in-situ dry density and moisture content tests are presented on the excavation logs in Appendix A. The results of the other laboratory tests are presented in Appendix B.

7. GEOLOGY AND SUBSURFACE CONDITIONS Our findings regarding regional and site geology, including faulting and seismicity, and groundwater conditions at the subject site are provided in the following sections.

7.1. Regional Geologic Setting The project is situated in the coastal foothill section of the Peninsular Ranges Geomorphic Province. This geomorphic province encompasses an area that extends approximately 900 miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja California (Harden, 2004; Norris and Webb, 1990). The province varies in width from approximately 30 to 100 miles. In general, the province consists of rugged mountains underlain by Jurassic metavolcanic and metasedimentary rocks, and Cretaceous igneous rocks of the southern California batholith. In the western portion of the province in San Die- go County, the metamorphic and granitic basement rocks are overlain by sedimentary materials that are Tertiary and Quaternary in age.

The Peninsular Ranges Province is traversed by a group of sub-parallel faults and fault zones trending roughly northwest. Several of these faults, which are shown on Figure 3, are considered active faults. The Elsinore, San Jacinto, and San Andreas faults are active fault systems located northeast of the site and the Rose Canyon, Coronado Bank, San Diego Trough, and San Clemente faults are active fault systems located west of the site. Major tectonic activity associated with these and other faults within this regional tectonic framework consists primarily of right-lateral, strike-slip movement. Further discussion of faulting relative to the site is provided in the Faulting and Seismicity section of this report.

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7.2. Site Geology The geology of the site vicinity is shown on Figure 4. Geologic units encountered during our subsurface exploration included fill, alluvium, and granitic rock. The alluvium includes un- divided alluvium and colluvium of Holocene and Pleistocene age (Todd, 2004). Previous geologic mapping (Tan, 2002) considered the surficial materials as late Pleistocene-age allu- vial deposits, also referred to as older alluvium.

Generalized descriptions of the units encountered during our subsurface exploration are provided in the subsequent sections. Additional descriptions of the subsurface units are provided on the boring and test trench logs in Appendix A.

7.2.1. Fill Fill was encountered at the ground surface in borings B-1, B-23, NM-1, NM-2, and NM-3 extending to depths of approximately 1½ to 4 feet below the ground surface. As encountered, fill materials generally consisted of reddish brown to brown, damp to moist, stiff, silty clay and medium dense, silty to clayey sand with some construction debris. In addition berms or mounds of earth were observed across the project site. Documentation regarding these fill materials was not available for review, but these fills are anticipated to be associated with the previous uses at the site including the Cajon Speedway, the motocross track, and the golf driving range. It has been our experience that deeper fills and buried debris may be present at the site that is related to the previous site use and demolition activities.

7.2.2. Alluvium Alluvium was encountered in our test trench and in each of our borings either at the ground surface or underlying the fill materials and extending to depths ranging from approximately 3 to 14½ feet. As encountered, the alluvium generally consisted of reddish brown and brown, damp to saturated, medium dense to very dense, fine sandy silt and clayey to silty sand with scattered gravel.

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7.2.3. Granitic Rock Cretaceous-age granitic rock was encountered in our exploratory borings, with the ex- ception of B-2, B-21, PT-1, PT-2, and PT-3. The granitic rock materials were observed to be underlying the alluvium and extending to the total depths explored. As encountered, this material was generally various shades of brown and gray, damp to saturated, fine- to coarse-grained, weathered granitic rock. Drilling refusal with the truck-mounted drill rig was encountered in borings B-8, B-13, and B-17.

7.3. Groundwater Groundwater was encountered during drilling of both phases of our subsurface exploration in borings B-1, B-9, NM-1, NM-2, and NM-3 at depths ranging from of approximately 8½ to 19 feet. Several hours after drilling, groundwater levels were noted to generally rise to depths of approximately 10 to 11 feet within borings NM-1 through NM-3. Groundwater was also encountered in our test trench TP-1 at a depth of approximately 12 feet during excavation. Af- ter approximately 6 days, the groundwater level within the piezometer for the test trench rose to a depth of approximately 9 feet. This depth corresponds to a groundwater elevation of approximately 370 feet above Mean Sea Level (MSL).

Based on our review of available onsite monitoring well data (Ametek, 2016), groundwater has been measured at depths as shallow as approximately 5½ feet within the project vicinity. Specifically, the report provides information regarding the monitoring of the groundwater elevation during fourth quarter of 2015. For this period, the report indicated a groundwater elevation of approximately 378 feet above MSL near the southeast corner of the site and a groundwater elevation of approximately 366 feet above MSL at the northwest corner of the site with a gradient toward the northwest. However, per the referenced Ametek 2016 report, groundwater elevations from monitoring well MW-23 near the northwest corner at the site has been at an elevation up to approximately 371 feet above MSL. Also, monitoring well MW-33A/B near the southeast corner of the site has been at an elevation up to approximately 381 feet above MSL. Fluctuations on the groundwater level and local conditions may occur

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due to variations in ground surface topography, subsurface geologic conditions and structure, rainfall, irrigation, and other factors.

7.4. Flood Hazards Based on our review of Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM), the western and southern portions of the project site are located within a mapped flood zone. While the 1% annual flood zone is generally confined to the Forester Creek Channel, the 0.2 percent annual chance flood zone (i.e. 500-year flood zone) is mapped across the southwestern half of the project site.

8. GEOLOGIC HAZARDS In general, geologic hazards associated with faulting and seismic activity include ground surface rupture, strong ground motion, liquefaction, and landsliding. These considerations are discussed in the following sections.

8.1. Faulting and Seismicity Based on our review of referenced geologic maps and stereoscopic aerial photographs, the ground surface in the vicinity of the subject site is not underlain by known active or potentially active faults (i.e., faults that exhibit evidence of ground displacement in the last 11,000 years and 2,000,000 years, respectively). However, the site is located in a seismically active area, as is the majority of southern California, and the potential for strong ground motion is considered significant during the design life of the proposed structures. The nearest known active fault is the Rose Canyon Fault, which is mapped approximately 13½ miles west of the project site (Figure 3).

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8.2. Ground Rupture Based on our review of the referenced geologic maps and literature and our site reconnaissance, no active faults are known to cross the project vicinity. Therefore, the potential for ground rupture due to faulting at the site is considered low. However, lurching or cracking of the ground surface as a result of nearby seismic events is possible.

8.3. Strong Ground Motion The 2013 California Building Code (CBC) specifies that the Risk-Targeted, Maximum

Considered Earthquake (MCER) ground motion response accelerations be used to evaluate

seismic loads for design of buildings and other structures. The MCER ground motion response accelerations are based on the spectral response accelerations for 5 percent damping in the direction of maximum horizontal response and incorporate a target risk for structural collapse equivalent to 1 percent in 50 years with deterministic limits for near- source effects. The horizontal peak ground acceleration (PGA) that corresponds to the

MCER for the site was calculated as 0.37g using the United States Geological Survey (USGS, 2016) seismic design tool (web-based).

The 2013 CBC specifies that the potential for liquefaction and soil strength loss be evaluat-

ed, where applicable, for the Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration with adjustment for site class effects in accordance with the Amer-

ican Society of Civil Engineers (ASCE) 7-10 Standard. The MCEG peak ground acceleration is based on the geometric mean peak ground acceleration with a 2 percent probability of ex-

ceedance in 50 years. The MCEG peak ground acceleration with adjustment for site class

effects (PGAM) was calculated as 0.35g using the USGS (USGS, 2016) seismic design tool

that yielded a mapped MCEG peak ground acceleration of 0.33g for the site and a site coeffi-

cient (FPGA) of 1.072 for Site Class C.

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8.4. Liquefaction and Seismically Induced Settlement Liquefaction of cohesionless soils can be caused by strong vibratory motion due to earthquakes. Research and historical data indicate that loose granular soils and non-plastic silts that are saturated by a relatively shallow groundwater table are susceptible to liquefaction. Based on the relatively dense nature of the underlying earth materials, it is our opinion that liquefaction and seismically induced settlements at the subject site are not design considerations for the project.

8.5. Landsliding The site is mapped within relative landslide susceptibility area 2, marginally susceptible (Tan, 1995). Based on our review of referenced geologic maps, literature, stereoscopic aerial photographs, and our geologic reconnaissance, no landslides or related features underlie the subject site. It is our opinion that the potential for significant large-scale slope instability at the site is not a design consideration due to the relatively flat nature of the site.

9. CONCLUSIONS Based on the results of our geotechnical evaluation, construction of the proposed development is feasible from a geotechnical perspective. There are no known geotechnical conditions that would preclude the proposed construction provided the recommendations of this report and appropriate construction practices are followed. The design and construction considerations for the proposed project include the following:

 The project site is underlain by fill, alluvium, and granitic rock. The fill is generally not considered suitable for support of proposed structures in its current state. Remedial grading should be performed to remove loose fill soils and replace them with compacted fill as recommended in this report. However, the alluvium and granitic rock are considered suitable for support of new engineered fills and the structures proposed as part of this project.

 Excavations in alluvium and granitic rock materials should be feasible with heavy earthmoving equipment in good working order. However, refusal was encountered in the granitic rock in several of our borings (B-8, B-13, and B-17). Where excavations are planned to extend into granitic rock, difficult ripping, the use of rock breakers and/or a rock wheel should be anticipated.

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 Groundwater was encountered in our borings B-1, B-9, NM-1, NM-2, and NM-3 and our exploratory test trench TP-1. The depths of the encountered groundwater ranged from approximately 8½ to 19 feet below the ground surface. Our background review indicated that groundwater was measured at the site at elevations ranging from approximately 366 feet above MSL at the northwest corner of the site to approximately 378 feet above MSL near the southeast corner of the site during the fourth quarter of 2015 (Ametek, 2016). However, the histori- historical data shows elevations as high as 371 feet above MSL at the northwest corner and approximately 381 feet above MSL near the southeast corner of the site (Ametek, 2016).

 On-site materials are generally suitable for reuse as engineered fill, provided they meet the criteria included in the following earthwork recommendations.

 The subject site is not located within a State of California Earthquake Fault Zone (Alquist- Priolo Special Studies Zone), and based on our review of published geologic maps, there are no known active faults underlying the site.

 The Rose Canyon fault zone is mapped approximately 13½ miles west of the project site. Accordingly, the potential for relatively strong seismic ground motions should be considered in the project design.

 Based on our evaluation, liquefaction and dynamic settlement are not design considerations for the project.

 Based on the results of our soil corrosivity testing presented in Appendix B, the site would be classified as corrosive to concrete in contact with soil per ACI 318.

 As noted previously, an easement for underground utilities crosses the site. We anticipate that grading will be performed above and around these utilities. Removal, placement and compaction of soils in close proximity to the utilities should be performed with care so that no damage occurs to the utilities.

10. RECOMMENDATIONS Based on the results of our subsurface exploration and our understanding of the proposed construction, we present the following geotechnical recommendations relative to the design and construction of the proposed project. The proposed construction should also be performed in accordance with the requirements of applicable governing agencies including the FAA and the San Diego County Department of Public Works. Note, this study did not include the preparation of pavement design recommendations for the airfield field relative pavements or vehicular pavements, as this was not within our scope of work.

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10.1. Earthwork In general, earthwork should be performed in accordance with the recommendations presented in this report and the requirements of applicable governing agencies including the FAA and the San Diego County Department of Public Works. Ninyo & Moore should be contacted for questions regarding the recommendations or guidelines presented herein.

10.1.1. Site Preparation Prior to performing excavations or other earthwork, the project site should be cleared of abandoned utilities (if present) and stripped of rubble, debris, vegetation, any loose, wet, or otherwise unstable soils, as well as surface soils containing organic material. Materials generated from the clearing operations should be removed from the site and disposed of at a legal dumpsite away from the project area.

10.1.2. Excavation Characteristics Based on our subsurface exploration of the site, the fill and older alluvium should be generally excavatable with heavy-duty earth working equipment in good working condition. Due to the presence of a shallow groundwater condition, on-site excavations that extend near or below the groundwater table may encounter sloughing and/or caving conditions.

However, excavations that extend into the granitic rock materials may be difficult to perform. During our subsurface excavation, drilling refusal within the granitic rock materials was encountered within borings (B-8, B-13, and B-17). Where excavations are planned to extend into granitic rock, difficult ripping, the use of rock breakers and/or a rock wheel should be anticipated. Contractors should, however, make their own independent evaluation of the excavation characteristics of the on-site materials prior to submitting their bids.

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10.1.3. Excavation Bottom Characteristics Based on our background review and the results of our subsurface exploration, there is a shallow groundwater table present at the site. Due to the relatively dense nature of the alluvium and granitic rock materials encountered beneath the groundwater table, relatively stable excavations bottoms were encountered within our exploratory excavations. How- ever, due to the wet conditions that exist in site excavations that extend near or below the groundwater table, soft and yielding subgrade conditions may be encountered. In general, the unstable bottom conditions may be mitigated by overexcavation and replacement with gravel or aggregate base materials. These materials may be combined with a geogrid product or wrapped in a non-woven geotextile fabric. However, specific recommendations for stabilizing excavation bottoms should be based on evaluation in the field by Ninyo & Moore at the time of construction.

10.1.4. Temporary Excavations For temporary excavations, we recommend that the following Occupational Safety and Health Administration (OSHA) soil classifications be used:

Fill and Alluvium Type C Granitic Rock Type B

Upon making the excavations, the soil classifications and excavation performance should be evaluated in the field by a competent person in accordance with the OSHA regulations. Temporary excavations should be constructed in accordance with OSHA recommendations. For trench or other excavations, OSHA requirements regarding personnel safety should be met using appropriate shoring (including trench boxes) or by laying back the slopes to no steeper than 1.5:1 (horizontal to vertical) in fill and alluvium and 1:1 in granitic bedrock material. Temporary excavations that encounter seepage may be shored or stabilized by placing sandbags or gravel along the base of the seepage zone. Excavations encountering seepage should be evaluated on a case-by-case basis. On-site safety of personnel is the responsibility of the contractor.

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10.1.5. Construction Dewatering As described in Section 7.3 of this report, a shallow groundwater table is present at the site. Due to the presence of shallow groundwater, dewatering is anticipated to be performed at the site for various excavations including excavation for the hydromodification vault. The dewatering scheme may include pumping of the groundwater from well points installed within or outside the excavations. Considerations for construction dewatering should include anticipated drawdown, volume of pumping, potential for settlement, and groundwater discharge. The well point system design should be evaluated by the specialty dewatering contractor. In general, we recommend that dewatering efforts extend to a depth of 3 feet below the bottom of excavations, including depth of bottom stabilization efforts. Testing and disposal of groundwater should be performed in accordance with the current guidelines of the Regional Water Quality Control Board (RWQCB).

10.1.6. Remedial Grading The existing fill materials are considered compressible and not suitable for structural support in their present condition. Due to the potential for excessive settlement of the existing fills, we recommend that the existing soils be overexcavated down to competent alluvium or granitic rock, whichever is shallower. Fills of varying depths should be anticipated at the site, due to the site’s prior uses consisting of the Cajon Speedway, a motocross track, and the golf driving range. The resultant overexcavation surfaces should be scarified to a depth of approximately 8 inches, moisture conditioned, and then recompacted to a relative compaction of 90 percent as evaluated by the ASTM International (ASTM) Test Method D 1557 prior to placing new fill. The resulting excavation should then be backfilled with engineered fills placed in accordance with the following recommendations. The extent and depths of removals and overexcavations should be evaluated by Ninyo & Moore’s representative in the field based on the materials exposed.

As described earlier in this report, fill materials we encountered in several of our excavations (B-1, B-23, NM-1, NM-2, and NM-3) to depths up to approximately 4 feet. However, the construction of the hydromodification vault in the northwest corner of the

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site is anticipated to address the presence of existing fills, therefore we do not anticipate additional remedial grading will be needed in this immediate area. Similarly, beneath the aprons, taxilanes, and the cross taxilanes, we anticipate that the planned grading for the new pavement sections and preparation of the exposed subgrade soils will address the presence of existing fills.

Although we encountered fill in excavations B-1, B-23, NM-1, NM-2, and NM-3 to depths of 4 feet, deeper fills and buried debris may be present at the site that is related to the previous site use and demolition activities. Accordingly, the precise locations along with the exact depths and extents of these existing fills are unknown at this time. For a preliminary estimate of quantities, the amount of overexcavation to be performed within the sheet graded lots will include an overexcavation depth of 4 feet at various locations or pockets of areas within the sheet graded lots. This depth can then be estimated at a combined cumulative area that is equivalent to approximately 1/10 of the total area associated with the sheet graded lots. This is based on the presence of fill within excavation B-23, which is located within one of the ten sheet graded lots. Note, this is a rough estimate based on widely spaced excavations performed as part of our evaluation. As described earlier, the depths and extents of the existing fill will vary at the site.

Additionally, backfills associated existing utilities to remain in place during and after construction will be encountered. In these areas, a sufficient thickness of backfill should be left in place during grading operations to protect the existing utility. The presence of these backfill materials should be considered during the development stages of the lots after the sheet grading operations.

10.1.7. Materials for Fill On-site soils with an organic content of less than approximately 3 percent by volume (or 1 percent by weight) are considered suitable for reuse as fill. Fill material should generally not contain rocks or lumps over approximately 4 inches, and generally not more than approximately 30 percent larger than ¾-inch. Utility trench backfill material should not contain rocks or lumps over approximately 3 inches in general. Soils classified as

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silts or clays should not be used for backfill in the pipe zone. Larger chunks, if generated during excavation, may be broken into acceptably sized pieces or should be disposed of off-site.

Import fill, if needed, should consist of clean, granular material that meets Standard Specifications for Public Works Construction (Greenbook) criteria for structure backfill. Soil should be tested for corrosive, expansive, and bearing (i.e., CBR) properties prior to importation. We recommend that imported materials be non-corrosive, and exhibit a very low expansion or swelling potential. In addition, the import fill should exhibit a CBR value of 10 or more. Import soils are considered non-corrosive if the materials possess a water-soluble sulfate content less than 0.10 percent by weight, a pH value more than 5.5, a water-soluble chloride content less than 500 parts per million (ppm), and an electrical resistivity more than 1,000 ohm-centimeters (ohm-cm). The import material should also possess a very low expansion potential when the swelling potential is measured to be less than 3 percent following the CBR test method as evaluated by ASTM D 1883 or the expansion index is measured to be less than 20 per ASTM D 4829. Materials for use as fill should be evaluated by Ninyo & Moore’s representative prior to filling or importing.

10.1.8. General Compacted Fill Prior to placement of general compacted fill, the contractor should request an evaluation of the exposed ground surface by Ninyo & Moore. Unless otherwise recommended, the exposed ground surface should then be scarified to a depth of approximately 8 inches and watered or dried, as needed, to achieve moisture contents generally above the optimum moisture content. The scarified materials should then be compacted to a relative compaction of 90 percent or more as evaluated in accordance with the ASTM D 1557. In the instance the removal surface is within the subgrade materials for vehicular pavements, then the materials should be recompacted to 95 percent, or if the materials are beneath airfield pavements, then they should be compacted in accordance with Section 10.1.9 of this report and FAA guidelines.

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The evaluation of compaction by the geotechnical consultant should not be considered to preclude any requirements for observation or approval by governing agencies. It is the contractor's responsibility to notify this office and the appropriate governing agency when project areas are ready for observation, and to provide reasonable time for that review.

Fill materials should be moisture conditioned to generally at or above the laboratory optimum moisture content prior to placement. The optimum moisture content will vary with material type and other factors. Moisture conditioning of fill soils should be generally consistent within the soil mass.

Prior to placement of additional compacted fill material following a delay in the grading operations, the exposed surface of previously compacted fill should be prepared to receive fill. Preparation may include scarification, moisture conditioning, and recompaction.

Compacted fill should be placed in horizontal lifts of approximately 8 inches in loose thickness. Prior to compaction, each lift should be watered or dried as needed to achieve a moisture content generally above the laboratory optimum, mixed, and then compacted by mechanical methods to a relative compaction of 90 percent for general fills, 95 percent for subgrade soils beneath vehicular pavements and the lower portions of airfield subgrade, or 100 percent beneath airfield pavements as evaluated by ASTM D 1557. Successive lifts should be treated in a like manner until the desired finished grades are achieved.

When compacting soil in close proximity to utilities, care should be taken by the grading contractor so that mechanical methods used to compact the soils do not damage the utilities. If the utility contractors indicate that it is undesirable to use compaction equipment in close proximity to a buried conduit, then the grading contractor may elect to use light mechanical compaction equipment or, with the approval of the geotechnical consultant, cover the conduit with clean granular material. These granular materials should be jetted in place to the top of the conduit. The granular material should have a sand equivalent more than 30 and should be used for backfilling the areas to be jetted.

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Jetting should generally be considered for trenches 2 feet or narrower in width and 4 feet or shallower in depth and relief pipes should be used. Following jetting operations, trench backfill should be mechanically compacted to the specified compaction to finish grade. Other methods of utility trench compaction may also be appropriate, upon review by the geotechnical consultant and the utility contractor at the time of construction.

10.1.9. Subgrade Compaction – Airfield Pavements The results of our evaluation indicate that the near-surface soils encountered during our subsurface exploration consist predominantly of clayey sand and silty sand. The CBR values of the granular soils are a function of the dry density and are presented in Ap- pendix B. CBR values at boring locations B-6 and B-11 (sample depth of approximately 0 to 5 feet), B-7 and B-14 (sample depth of approximately 0 to 7 feet), B-15 and B-17 (sample depth of approximately 0 to 4 feet), B-16 and PT-4 (sample depth of approximately 0 to 4 feet), B-20 and B-21 (sample depth of approximately 0 to 4 feet), and B- 23 and B-24 (sample depth of approximately 0 to 5 feet) are 8, 19, 34, 12, 13, and 12, respectively, for a pavement subgrade with a relative compaction of 100 percent. Based on our experience and judgment, a design CBR value of 8 for non-cohesive soils is appropriate for the site.

In order to remediate the variable subgrade conditions existing within the project area and in general accordance with FAA subgrade compaction requirements for 60,000-pound aircrafts with dual wheels, we recommend that the structural pavement sections (both AC and concrete pavements) be underlain by 17 inches of engineered fill compacted to a relative compaction of 100 percent, further underlain by 13 inches of engineered fill compacted to 95 percent relative compaction per ASTM D 1557. The pavement structural section is considered to be comprised of the AC or concrete pavement, an aggregate base course material, and a sub-base material. Per FAA guidelines, sub-base may be excluded from a pavement structural section if the subgrade soils con- sistently exhibit a CBR value of 20 or more.

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10.1.10. Subgrade Preparation – Hydromodification Vault Based on our review of the project plans (KHA, 2016), we understand that a below grade hydromodification vault will be constructed at the northwest corner of the site. This structure is anticipated to extend to a depth of approximately 11 feet below the finished surface. From a review of our exploratory excavations at the vault’s location, we anticipate that the excavation for the vault will extend into alluvium or granitic rock. To prepare a relatively stable base beneath the bottom of the vault’s foundation, we recommend that 12 inches of aggregate base materials be placed beneath the foundation. These aggregate base materials should be placed within a dewatered excavation at a relative compaction of 90 percent.

10.1.11. Lateral Pressures for Thrust Blocks Thrust restraint for buried pipelines may be achieved by transferring the thrust force to the soil outside the pipe through a thrust block. Thrust blocks may be designed using the lateral passive earth pressures presented on Figure 5. Thrust blocks should be backfilled with granular backfill material and compacted in accordance with recommendations presented in this report.

10.1.12. Pipe Bedding and Modulus of Soil Reaction (E') We recommend that the new pipelines (pipes), where constructed in open excavations, be supported on 6 or more inches of granular bedding material. Granular pipe bedding should be provided to distribute vertical loads around the pipe. Bedding material and compaction requirements should be in accordance with this report. Pipe bedding typically consists of graded aggregate with a coefficient of uniformity of three or more.

The modulus of soil reaction (E’) is used to characterize the stiffness of soil backfill placed at the sides of buried flexible pipes for the purpose of evaluating deflection caused by the weight of the backfill over the pipe (Hartley and Duncan, 1987). A soil reaction modulus of 1,200 pounds per square inch (psi) may be used for excavation depths less than 5 feet and 1,800 psi may be used for excavation depths of 5 to 10 feet,

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backfilled with granular soil placed at a relative compaction of 90 percent or more. A soil reaction modulus of 2,100 psi may be used for trenches deeper than 10 feet.

10.1.13. Pipe Zone Backfill The pipe zone backfill should be placed one top of the pipe bedding material and extend to 1 foot or more above the top of the pipe in accordance with the recent edition of the Standard Specifications for Public Works Construction (“Greenbook”). Pipe zone backfill should have a Sand Equivalent (SE) of 30 or more, and be placed around the sides and top of the pipe. Special care should be taken not to allow voids beneath and around the pipe. Compaction of the pipe zone backfill should proceed up both sides of the pipe.

It has been our experience that the voids within a crushed rock material are sufficiently large to allow fines to migrate into the voids, thereby creating the potential for sinkholes and depressions to develop at the ground surface. If open-graded gravel is utilized as pipe zone backfill, this material should be wrapped with a geosynthetic filter fabric.

Additionally, we understand that regional utility water districts have their own specifications regarding the materials and relative compactions that may be used for backfill of trenches for water lines. The recommendations in this report may be different than those required by the governing water agency. In those instances, the governing water agency specifications would supersede the recommendations provided in this report.

10.1.14. Utility Trench Zone Backfill Based on our subsurface evaluation, the on-site earth materials should be generally suitable for reuse as trench zone backfill of utilities provided they are free of organic material, clay lumps, debris, and rocks greater than approximately 3 inches in diameter. Fill should be moisture-conditioned to generally above the laboratory optimum. Trench backfill should be compacted to 90 percent of its modified Proctor density as evaluated by ASTM D 1557 except for the upper 12 inches of the backfill beneath vehicular pavement sections that should be compacted to 95 percent of its modified Proctor density as evaluated by ASTM D 1557. Utility trench zone compaction beneath airfield

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pavements should also follow the recommendations for relative compactions presented in Section 10.1.9. Lift thickness for backfill will depend on the type of compaction equipment utilized, but fill should generally be placed in lifts not exceeding 8 inches in loose thickness. Special care should be exercised to avoid damaging the pipe during compaction of the backfill.

10.1.15. Drainage Roof and pad drainage should be conveyed away from structures to suitable discharge areas by nonerodible devices (e.g., gutters, downspouts, concrete swales, etc.). Posi- tive drainage adjacent to structures should be established and maintained. Positive drainage may be accomplished by providing drainage away from the foundations of the structure at a gradient of 2 percent or steeper for a distance of 5 feet or more outside the building perimeter, and further maintained by a graded swale leading to an appropriate outlet, in accordance with the recommendations of the project civil engineer and/or landscape architect.

Surface drainage on the site should be provided so that water is not permitted to pond. A gradient of 2 percent or steeper should be maintained over the pad area and drainage patterns should be established to divert and remove water from the site to appropriate outlets.

Care should be taken by the contractor during final grading to preserve any berms, drainage terraces, interceptor swales or other drainage devices of a permanent nature on or adjacent to the property. Drainage patterns established at the time of final grading should be maintained for the life of the project. The property owner and the mainte-

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nance personnel should be made aware that altering drainage patterns might be detri- mental to foundation performance.

10.2. Seismic Design Considerations Design of the proposed improvements should be performed in accordance with the requirements of governing jurisdictions and applicable building codes. Table 2 presents the seismic design parameters for the site in accordance with the CBC (2013) guidelines and adjusted

MCER spectral response acceleration parameters (USGS, 2016).

Table 2 – 2013 California Building Code Seismic Design Criteria Site Coefficients and Spectral Response Acceleration Parameters Values Site Class C Site Coefficient, Fa 1.052 Site Coefficient, Fv 1.462 Mapped Short Period Spectral Acceleration at 0.2-second Period, SS 0.871 g Mapped One-Second Period Spectral Acceleration at 1.0-second Period, S1 0.338g Short Period Spectral Acceleration at 0.2-second Period Adjusted For Site Class, SMS 0.916g One-Second Period Spectral Acceleration at 1.0-second Period Adjusted For Site Class, SM1 0.494g Design Short Period Spectral Acceleration at 0.2-second Period, SDS 0.611g Design One-Second Period Spectral Acceleration at 1.0-second Period, SD1 0.329g

10.3. Underground Structures We understand that the project will include the construction of below grade structures, including the hydromodification vault at the northwest corner of the site. The following sections provide recommendations for the design of below grade structures.

10.3.1. Mat Foundations Below grade structures may be designed using an allowable bearing pressure of 3,000 pounds per square foot (psf). This assumes that the mat foundation is embedded 18 inches below the lowest adjacent grade and is bearing on competent engineered fill, alluvium or granitic rock. This allowable bearing capacity may be increased by one- third when considering loads of a short duration such as wind or seismic forces. Thick- ness and reinforcement of the mat foundation should be in accordance with the recommendations of the project structural engineer.

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Mat foundations typically experience some deflection due to loads placed on the mat and the reaction of the soils underlying the mat. A design coefficient of subgrade reac-

tion, Kv1, of 150 pounds per cubic inch (pci) may be used for evaluating such deflec- deflections at the subject sites. This value is based on a unit square-foot area and should

be adjusted for the planned mat size. The coefficient of subgrade reaction Kb for a mat of specific width may be evaluated using the following equation:

2 Kb = Kv1[(b+1)/2b]

where b is the width of the foundation in feet.

10.3.2. Lateral Pressures Underground structures may be designed for the lateral pressures represented by the pressure diagram on Figure 6. The passive pressure value assumes that the ground is horizontal for a distance of 10 feet, or three times the height generating the passive pressure, whichever is more. We recommend that the upper 1 foot of soil not protected by pavement or a concrete slab be neglected when calculating passive resistance.

For frictional resistance to lateral loads, we recommend a coefficient of friction of 0.35 be used between soil and concrete. The allowable lateral resistance can be taken as the sum of the frictional resistance and passive resistance provided the passive resistance does not exceed one-half of the total allowable resistance. The passive resistance values may be increased by one-third when considering loads of short duration such as wind or seismic forces.

Per the referenced Ametek 2016 report, groundwater elevations from monitoring well MW-23 near the northwest corner at the site has been at an elevation up to approximately 371 feet above MSL. During our recent phase of the subsurface exploration, groundwater was measured at a depth of approximately 9 feet within our test trench TP-1. This depth corresponds to a groundwater elevation of approximately 370 feet above MSL. Also, monitoring well MW-33A/B near the southeast corner of the site has been at an elevation up to approximately 381 feet above MSL. The groundwater gradient is from the southeast towards the northwest. For preliminary design purposes

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associated with the hydromodification vault, we recommend that a groundwater elevation of 371 feet above MSL be used for evaluation of lateral pressures. The design groundwater elevation for other underground structures at the site should be evaluated based on an extrapolation of the groundwater elevations presented above for the northwest and southeast portions of the site.

It is recommended that the exterior of underground walls, and horizontal and vertical construction joints be waterproofed, as indicated by the project civil engineer. For pipe wall penetrations into the hydromodification vault, and other structures, standard “water-tight” penetration design should be utilized. To reduce the potential for relative pipe to wall differential settlement, which could cause pipe shearing, we recommend that a pipe joint be located close to the exterior of the wall. The type of joint should be such that minor relative movement can be accommodated without distress

10.3.3. Uplift Considerations We recommend that the underground structures be designed to resist hydrostatic uplift in accordance with Figure 7. As described above, for preliminary design purposes associated with the hydromodification vault, we recommend that a groundwater elevation of 371 feet above MSL be used for evaluation of the factor of safety against uplift. The design groundwater elevation for other underground structures at the site should be evaluated based on an extrapolation of the groundwater elevations presented above for the northwest and southeast portions of the site.

Alternative design measures for resisting the anticipated uplift pressure could include installation of vertical anchors, increasing mass by constructing a thicker concrete mat foundation, or extending the foundation a selected distance outside the exterior walls of the lift station/vaults (flanges). The resistance to uplift may then be taken as the sum of the weight of the structure and the weight of the soil wedge within the zone of influence of the flanges shown on Figure 7.

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10.3.4. Static Settlement We estimate that the proposed structures, designed and constructed as recommended herein, will undergo total settlement on the order of 1 inch. Differential settlement on the order of ½ inch over a horizontal span of 40 feet should be expected.

10.4. Concrete Flatwork Exterior concrete flatwork should be 5 inches in thickness and should be reinforced with No. 3 reinforcing bars placed at 24 inches on-center both ways. No vapor retarder is needed for exterior flatwork. To reduce the potential manifestation of distress to exterior concrete flatwork due to movement of the underlying soil, we recommend that such flatwork be installed with crack-control joints at appropriate spacing as designed by the project engineer. The subgrade soils should be scarified to a depth of 8 inches, moisture conditioned to generally above the laboratory optimum moisture content, and compacted to 90 percent of its modified Proctor density as evaluated by ASTM D 1557. Positive drainage should be established and maintained adjacent to flatwork

10.5. Corrosion Laboratory testing was performed on representative samples of the on-site earth materials to evaluate pH and electrical resistivity, as well as chloride and sulfate contents. The pH and electrical resistivity tests were performed in accordance with California Test (CT) 643 and the sulfate and chloride content tests were performed in accordance with CT 417 and CT 422, respectively. These laboratory test results are presented in Appendix B.

The results of the corrosivity testing indicated electrical resistivities ranging from approximately 1,000 to 2,500 ohm-cm, soil pH values ranging from approximately 6.3 to 7.8, chloride contents of approximately 215 to 400 ppm, and sulfate contents of approximately 0.002 to 0.110 percent (i.e., 20 to 1,100 parts per million [ppm]). Based on the Caltrans corrosion (2012) criteria, the on-site soils would be classified as corrosive, which is defined as soils with electrical resistivities less than 1,000ohm-cm, more than 500 ppm chlorides, more than 0.1 percent sulfates, and/or a pH less than 5.5.

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10.6. Concrete Concrete in contact with soil or water that contains high concentrations of water-soluble sulfates that can be subject to premature chemical and/or physical deterioration. As noted, the soil samples tested in this evaluation indicated water-soluble sulfate contents of approximately 0.002 and 0.110 percent by weight (i.e., about 20 and 1,100 ppm). According to ACI 318, the potential for sulfate attack is moderate for water soluble sulfate contents in soils ranging from about 0.1 to 0.2 percent by weight. Since some on-site soils possess a moderate potential for sulfate attack, we recommend that Type II or V cement be used for concrete construction that is in contact with soil. Also, the concrete should have a water cement ratio no more than 0.50 by weight for normal weight aggregate concrete and a 28 day compressive strength of 4,000 pounds per square inch (psi) or more.

10.7. Pre-Construction Conference We recommend that a pre-construction meeting be held prior to commencement of grading. The owner or his representative, the agency representatives, the architect, the civil engineer, Ninyo & Moore, and the contractor should attend to discuss the plans, the project, and the proposed construction schedule.

10.8. Plan Review and Construction Observation The conclusions and recommendations presented in this report are based on analysis of observed conditions in widely spaced exploratory borings. If conditions are found to vary from those described in this report, Ninyo & Moore should be notified, and additional recommendations will be provided upon request. Ninyo & Moore should review the final project drawings and specifications prior to the commencement of construction. Ninyo & Moore should perform the needed observation and testing services during construction operations.

The recommendations provided in this report are based on the assumption that Ninyo & Moore will provide geotechnical observation and testing services during construction. In the event that it is decided not to utilize the services of Ninyo & Moore during construction, we request that the selected consultant provide the client with a letter (with a copy to Ninyo &

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Moore) indicating that they fully understand Ninyo & Moore’s recommendations, and that they are in full agreement with the design parameters and recommendations contained in this report. Construction of proposed improvements should be performed by qualified subcon- tractors utilizing appropriate techniques and construction materials.

11. LIMITATIONS The field evaluation, laboratory testing, and geotechnical analyses presented in this geotechnical report have been conducted in general accordance with current practice and the standard of care exercised by geotechnical consultants performing similar tasks in the project area. No warranty, expressed or im- plied, is made regarding the conclusions, recommendations, and opinions presented in this report. There is no evaluation detailed enough to reveal every subsurface condition. Variations may exist and conditions not observed or described in this report may be encountered during construction. Uncertain- ties relative to subsurface conditions can be reduced through additional subsurface exploration. Additional subsurface evaluation will be performed upon request. Please also note that our evaluation was limited to assessment of the geotechnical aspects of the project, and did not include evaluation of structural issues, environmental concerns, or the presence of hazardous materials.

This document is intended to be used only in its entirety. No portion of the document, by itself, is designed to completely represent any aspect of the project described herein. Ninyo & Moore should be contacted if the reader requires additional information or has questions regarding the content, interpretations presented, or completeness of this document.

This report is intended for design purposes only. It does not provide sufficient data to prepare an accurate bid by contractors. It is suggested that the bidders and their geotechnical consultant perform an independent evaluation of the subsurface conditions in the project areas. The independent evaluations may include, but not be limited to, review of other geotechnical reports prepared for the adjacent areas, site reconnaissance, and additional exploration and laboratory testing.

Our conclusions, recommendations, and opinions are based on an analysis of the observed site conditions. If geotechnical conditions different from those described in this report are encountered,

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our office should be notified and additional recommendations, if warranted, will be provided upon request. It should be understood that the conditions of a site could change with time as a result of natural processes or the activities of man at the subject site or nearby sites. In addition, changes to the applicable laws, regulations, codes, and standards of practice may occur due to government ac- tion or the broadening of knowledge. The findings of this report may, therefore, be invalidated over time, in part or in whole, by changes over which Ninyo & Moore has no control.

This report is intended exclusively for use by the client. Any use or reuse of the findings, conclusions, and/or recommendations of this report by parties other than the client is undertaken at said parties’ sole risk.

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12. REFERENCES

American Concrete Institute (ACI), 2011, ACI 318 Building Code Requirements for Structural Concrete and Commentary. American Society of Civil Engineers (ASCE), 2010, Minimum Design Loads for Buildings and Other Structures, ASCE 7-10. Ametek, Inc., 2016, Groundwater Monitoring Report – Fourth Quarter 2015, Former Ketema A&E Facility, 790 Greenfield Drive, El Cajon, California: dated January 29. Anderson, J.G., Rockwell, T.K., and Agnew, D.C., 1989, Past and Possible Future Earthquakes of Significance to the San Diego Region: Earthquake Engineering Research Institute (EERI), Earthquake Spectra, Volume 5, No. 2. Building News, 2012, “Greenbook””, Standard Specification for Public Works Construction: BNI Publications. California Building Standards Commission, 2013, California Building Code (CBC), Title 24, Part 2, Volumes 1 and 2. California Department of Transportation (Caltrans), 2012, Corrosion Guidelines (Version 2.0), Divi- sion of Engineering and Testing Services, Corrosion Technology Branch: dated November. California Geological Survey, 1998, Maps of Known Active Fault Near-Source Zones in Califor- nia and Adjacent Portions of Nevada: dated February. California Geological Survey, 2008b (revised), Earthquake Shaking Potential for California: Map Sheet 48. County of San Diego, 2010, Department of Environmental Health, Land and Water Quality Divi- sion, Design Manual for Onsite Wastewater Treatment Systems: dated March 23 (updated 11-25-13). Federal Aviation Administration (FAA), 2009, Airport Pavement Design and Evaluation, Adviso- ry Circular, United States Department of Transportation, AC No. 150/5320-6E: dated September 30. Geotracker, 2016, http://geotracker.swrcb.ca.gov/. Google, Inc., 2015, www.googleearth.com. Harden, D.R., 2004, California Geology, 2nd edition: Prentice Hall, Inc. Hartley, J.D. and Duncan, J.M., 1987, “E” and Its Variation with Depth, ASCE Journal of Trans- portation, Volume 113, No. 5, 538-553. Jennings, C.W. and Bryant, W.A., 2010, Fault Activity Map of California: California Geological Survey, Geologic Data Map Series, Map No. 6, Scale 1:750,000.

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Kimley-Horn, 2016, Plans for Construction of Cajon Air Center at Gillespie Field, County of San Diego, California, 190 Sheets: dated January. Ninyo & Moore, In-house proprietary information. Ninyo & Moore, 1998, Preliminary Geotechnical Evaluation Report, Marshall Avenue Extension Project, Gillespie Field, El Cajon, California: dated August 31. Ninyo & Moore, 2005a, Screening Level Site Assessment Report, Cajon Speedway, El Cajon, California: dated March 16. Ninyo & Moore, 2005b, Water Well and Forester Creek Tributary Sampling and Analysis, Cajon Speedway Site, El Cajon, California: dated July 29. Ninyo & Moore, 2006, Groundwater Sampling Report, Parcel 98-1027-B, Gillespie Field, El Ca- jon, California: dated June 15. Ninyo & Moore, 2008, Groundwater Monitoring, Well Installation and Sampling, County of San Diego, Department of Sheriff-Astrea Division, 1745 North Marshall Avenue, El Cajon, California: dated September 5. Ninyo & Moore, 2009, Geotechnical Evaluation (DRAFT), Proposed 70-Acre Cajon Air Center Development, Gillespie Field Airport, El Cajon, California: dated March 24. Ninyo & Moore, 2016, Proposal for Supplemental Geotechnical and Environmental Services, Ca- jon Air Center at Gillespie Field, El Cajon, California: dated March 23. Norris, R.M., and Webb, R.W., 1990, Geology of California, Second Edition: John Wiley & Sons. Tan, S.S., 2002, Geologic Map of the El Cajon 7.5’ Quadrangle, California: A Digital Database, California Geological Survey, Scale 1:24,000. Todd, V.R., 2004, Preliminary Geologic Map of the El Cajon 30’ x 60’ Quadrangle, Southern California, Scale 1:100,000. Treiman, J.A., 1993, The Rose Canyon Fault Zone, Southern California: California Division of Mines and Geology, Open-File Report 93-02. United States Federal Emergency Management Agency (FEMA), 2012, Flood Insurance Rate Map (FIRM), Map Panels 1653 and 1654 of 2375, dated May 16. United States Geological Survey, 1996, Topographic Map of the El Cajon Quadrangle, Califor- nia: 7.5-minute series, Scale 1:24,000. United States Geological Survey, 2015, Topographic Map of the El Cajon Quadrangle, Califor- nia: 7.5-minute series, Scale 1:24,000. United States Geological Survey, 2016, Ground Motion Parameter Calculator – Version 5.1.0; World Wide Web, http://earthquake.usgs.gov/research/hazmaps.design/: accessed April 13.

108139001 R Revised.doc 32 Cajon Air Center at Gillespie Field May 11, 2016 El Cajon, California Project No. 108139001

AERIAL PHOTOGRAPHS Source Date Flight Numbers Scale USDA April 14, 1953 AXN-9M 154 and 155 1:24,000

108139001 R Revised.doc 33 SITE

Floyd Smith Dr.

MAP INDEX SOURCE: ESRI WORLD TOPO, 2016

15 Sa n Diego SCALE IN FEET 5 Co unty

0 1,500 3,000 8 L D J

1 NOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. 0 2 / 2 / 5

x FIGURE m

. SITE LOCATION L S _ 1

0 PROJECT NO. DATE 0 9 CAJON AIR CENTER AT GILLESPIE FIELD 3 1 8

0 EL CAJON, CALIFORNIA 1 108139001 5/16 1 _ 1 PROPOSED HYDROMODIFICATION VAULT PT-5 NM-1 TD=6.0 TD=21.3 B-3 B-2 TD=10.0 B-4 TD=10.0 B-1 TD=10.0 PT-1 TD=21.0 TD=6.0 B-5 NM-2 B-6 B-7 B-8 TD=6.5 TD=21.0 TD=10.0 TD=10.0 TD=15.5 TP-1 TD=12.0 B-10 B-9 TD=5.0 TD=16.0 NM-3 TD=21.5 B-11 B-12 TD=10.0 TD=8.4

B-14 TD=10.0 B-13 TD=9.5

B-15 TD=10.0 B-16 PT-4 TD=10.0 TD=6.0 PT-2 TD=3.0 B-18 B-17 TD=10.0 TD=9.5 B-19 B-20 TD=10.0 TD=13.0

B-21 TD=7.0

B-23 B-22 TD=16.0 TD=12.5 B-24 TD=9.5

B-25 TD=21.0 PT-3 TD=3.0

LEGEND

SITE BOUNDARY

NM-3 TD=21.5 BORING (2016) TD=TOTAL DEPTH IN FEET

TP-1 TD=12.0 TEST TRENCH (2016) TD=TOTAL DEPTH IN FEET SOURCES: KIMLEY-HORN, 2016; GOOGLE EARTH, 2016 B-25 TD=21.0 BORING (2009) TD=TOTAL DEPTH IN FEET PT-5 SCALE IN FEET

L TD=6.0 PERCOLATION TEST (2009) D J

TD=TOTAL DEPTH IN FEET 0 400 800 6 1 0 2 / 9 2

/ NOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. 4

d x m . FIGURE L

B EXPLORATION LOCATIONS _ 1 0 0

9 PROJECT NO. DATE 3 CAJON AIR CENTER AT GILLESPIE FIELD 1 8

0 EL CAJON, CALIFORNIA 1 108139001 5/16 2 _ 2 Tulare Inyo County County CA L IF O RN IA

P O S N O C E C A V R E L A E IF D K O A R N I A

B L A C K W Kern A T LF County H E O A R W R P TE E HI R W CK O LO L CK AR H HEELER G AR W T IX AN TO M EI PL C San Bernardino M A H L L IR I A E C U County L O G E D E N S V C P L A A D A N L A L M I O A L L E S E P G W N E N R C D Y A P L R W O INE E E O C H MO AR A J UN W S O O K TA S ATER IN FA D H A U N N L S B T O U Z L SAN ON N L G E V IO CAYETANO A F A N B R L E R ON L M M IE T E Ventura L A Y E O SANTA H L R U County Los Angeles T S N NTA SUSANA R O T SA O N County N A OSA I R E SI N IDG ER T HR R PI GA ORT A SAW ON ON N MA ANY AM DR E C CUC E M I OUNTAIN OS S S O M N J I O NT SA N C PI MA TA MONICA R E E LIBU COAST AN K N S C C E W H H W H I A I T N R P T I O B A N N I N O E R N G BLUE CUT O R C T K - I N G S L A E S W N Riverside A O N O Orange G P L J County A A D County E A N L N D S O C A R S I I E N V N Y A T V T S A E K R O F LTON CREE C D A SA R E U U S L Z T -S O Z A F O N O F C N T F S C L E A D H O A C O Y R A E O K TA F R B LI O E T NA E R RI R Z Imperial DGE M O C A A N R E W T E San Diego E R County I H L O E O C E N K Z County M Y N O S E E L A A A L E N S S R R N T SU E E I PE I C N H RS S S O Q TI M L U T R IO I E A SITE C E A N M N C R K E H E IL D O O N V L T I R S A S E E O L G E L N E O A Y I T D C M R O P A P a c i f i c O L E B N R U A A S G I G Y A U A O c e a n N U S A L H O L N K A A D N O M E X I C A

LEGEND SOURCE: U.S. GEOLOGICAL SURVEY AND CALIFORNIA GEOLOGICAL SURVEY, 2006, QUATERNARY FAULT AND FOLD DATABASE FOR THE UNITED STATES.

L CALIFORNIA FAULT ACTIVITY D J

HISTORICALLY ACTIVE QUATERNARY M

P (POTENTIALLY ACTIVE) SCALE IN MILES 1 HOLOCENE ACTIVE 4 : 0 2 : LATE QUATERNARY STATE/COUNTY BOUNDARY 3 0 30 60 6 (POTENTIALLY ACTIVE) 1 0 2 / 9

2 NOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. / 4

d x m . FIGURE L

F FAULT LOCATIONS _ 1 0 0

9 PROJECT NO. DATE 3

1 CAJON AIR CENTER AT GILLESPIE FIELD 8

0 EL CAJON, CALIFORNIA 1 108139001 5/16

_ 3 3 SITE

LEGEND

SOURCE: TODD, V.R., 2004, PRELIMINARY GEOLOGIC MAP OF THE EL CAJON 30' X 60' QUADRANGLE, SOUTHERN CALIFORNIA

SCALE IN FEET L D J

0 4,000 8,000 6 1 0 2 /

9 NOTE: DIRECTIONS, DIMENSIONS AND LOCATIONS ARE APPROXIMATE. 2 / 4

d x

m FIGURE .

G GEOLOGY _ 1 0 0

9 PROJECT NO. DATE 3 CAJON AIR CENTER AT GILLESPIE FIELD 1 8

0 EL CAJON, CALIFORNIA 1 108139001 5/16 4 _ 4

Cajon Air Center at Gillespie Field May 11, 2016 El Cajon, California Project No. 108139001

APPENDIX A

EXCAVATION LOGS

Field Procedure for the Collection of Disturbed Samples Disturbed soil samples were obtained in the field using the following methods.

Bulk Samples Bulk samples of representative earth materials were obtained from the exploratory excavations. The samples were bagged and transported to the laboratory for testing.

The Standard Penetration Test (SPT) Sampler Disturbed drive samples of earth materials were obtained by means of a Standard Penetra- tion Test sampler. The sampler is composed of a split barrel with an external diameter of 2 inches and an unlined internal diameter of 1-3/8 inches. The sampler was driven into the ground 12 to 18 inches with a 140-pound hammer free-falling from a height of 30 inches in general accordance with ASTM D 1586. The blow counts were recorded for every 6 inches of penetration; the blow counts reported on the logs are those for the last 12 inches of penetration. Soil samples were observed and removed from the sampler, bagged, sealed and transported to the laboratory for testing.

Field Procedure for the Collection of Relatively Undisturbed Samples Relatively undisturbed soil samples were obtained in the field using the following method.

The Modified Split-Barrel Drive Sampler The sampler, with an external diameter of 3.0 inches, was lined with 1-inch long, thin brass rings with inside diameters of approximately 2.4 inches. The sample barrel was driven into the ground with the weight of a hammer of the drill rig in general accordance with ASTM D 3550. The driving weight was permitted to fall freely. The approximate length of the fall, the weight of the hammer, and the number of blows per foot of driving are presented on the boring logs as an index to the relative resistance of the materials sampled. The samples were removed from the sample barrel in the brass rings, sealed, and transported to the laboratory for testing.

108139001 R Revised.doc SAMPLES BORING LOG EXPLANATION SHEET U.S.C.S. SYMBOL DEPTH (feet) BLOWS/FOOT MOISTURE (%) Bulk CLASSIFICATION Driven DRY DENSITY (PCF) 0 Bulk sample.

Modified split-barrel drive sampler.

2-inch inner diameter split-barrel drive sampler.

No recovery with modified split-barrel drive sampler, or 2-inch inner diameter split-barrel drive sampler.

Sample retained by others.

5 Standard Penetration Test (SPT).

No recovery with a SPT.

XX/XX Shelby tube sample. Distance pushed in inches/length of sample recovered in inches.

No recovery with Shelby tube sampler.

Continuous Push Sample.

10 Seepage. Groundwater encountered during drilling. Groundwater measured after drilling. SM MAJOR MATERIAL TYPE (SOIL): Solid line denotes unit change. CL Dashed line denotes material change.

Attitudes: Strike/Dip b: Bedding c: Contact 15 j: Joint f: Fracture F: Fault cs: Clay Seam s: Shear bss: Basal Slide Surface sf: Shear Fracture sz: Shear Zone sbs: Shear Bedding Surface

The total depth line is a solid line that is drawn at the bottom of the boring.

BORING LOG

Explanation of Boring Log Symbols PROJECT NO. DATE FIGURE SOIL CLASSIFICATION CHART PER ASTM D 2488 GRAIN SIZE SECONDARY DIVISIONS SIEVE GRAIN APPROXIMATE PRIMARY DIVISIONS DESCRIPTION GROUP SYMBOL GROUP NAME SIZE SIZE SIZE

GW well-graded GRAVEL Larger than CLEAN GRAVEL Boulders > 12” > 12” less than 5% fines basketball-sized GP poorly graded GRAVEL

Fist-sized to GW-GM well-graded GRAVEL with silt Cobbles 3 - 12” 3 - 12” GRAVEL basketball-sized GRAVEL with more than GP-GM poorly graded GRAVEL with silt DUAL 50% of CLASSIFICATIONS Thumb-sized to coarse GW-GC well-graded GRAVEL with clay Coarse 3/4 - 3” 3/4 - 3” 5% to 12% fines fist-sized fraction retained on GP-GC poorly graded GRAVEL with clay Gravel No. 4 sieve Pea-sized to Fine #4 - 3/4” 0.19 - 0.75” GM silty GRAVEL thumb-sized GRAVEL with COARSE- FINES GC clayey GRAVEL GRAINED more than Rock-salt-sized to 12% fines Coarse #10 - #4 0.079 - 0.19” SOILS GC-GM silty, clayey GRAVEL pea-sized more than 50% retained SW well-graded SAND Sugar-sized to CLEAN SAND Sand Medium #40 - #10 0.017 - 0.079” on No. 200 less than 5% fines rock-salt-sized SP poorly graded SAND sieve 0.0029 - Flour-sized to SW-SM well-graded SAND with silt Fine #200 - #40 0.017” sugar-sized SAND SAND with SP-SM poorly graded SAND with silt 50% or more DUAL of coarse CLASSIFICATIONS Flour-sized and SW-SC well-graded SAND with clay Fines Passing #200 < 0.0029” fraction 5% to 12% fines smaller passes SP-SC poorly graded SAND with clay No. 4 sieve SM silty SAND PLASTICITY CHART SAND with FINES more than SC clayey SAND 12% fines SC-SM silty, clayey SAND 70

CL lean CLAY 60

INORGANIC ML SILT 50 SILT and CLAY CH or OH CL-ML silty CLAY liquid limit 40 less than 50% FINE- OL (PI > 4) organic CLAY 30 ORGANIC GRAINED CL or OL MH or OH OL (PI < 4) organic SILT SOILS 20 50% or CH fat CLAY more passes INORGANIC 10 SILT and INDEX (PI), % PLASTICITY 7 No. 200 sieve MH elastic SILT CL - ML ML or OL CLAY 4 0 liquid limit OH (plots on or organic CLAY 0 10 20 30 40 50 60 70 80 90 100 50% or more above “A”-line) ORGANIC OH (plots below LIQUID LIMIT (LL), % organic SILT “A”-line) Highly Organic Soils PT Peat

APPARENT DENSITY - COARSE-GRAINED SOIL CONSISTENCY - FINE-GRAINED SOIL SPOOLING CABLE OR CATHEAD AUTOMATIC TRIP HAMMER SPOOLING CABLE OR CATHEAD AUTOMATIC TRIP HAMMER APPARENT MODIFIED MODIFIED MODIFIED MODIFIED SPT SPT CONSIS- DENSITY SPT SPLIT BARREL SPT (blows/foot) SPLIT BARREL (blows/foot) SPLIT BARREL TENCY (blows/foot) (blows/foot) SPLIT BARREL (blows/foot) (blows/foot) (blows/foot) (blows/foot) Very Loose < 4 < 8 < 3 < 5 Very Soft < 2 < 3 < 1 < 2

Loose 5 - 10 9 - 21 4 - 7 6 - 14 Soft 2 - 4 3 - 5 1 - 3 2 - 3 Medium Firm 5 - 8 6 - 10 4 - 5 4 - 6 11 - 30 22 - 63 8 - 20 15 - 42 Dense Stiff 9 - 15 11 - 20 6 - 10 7 - 13 Dense 31 - 50 64 - 105 21 - 33 43 - 70 Very Stiff 16 - 30 21 - 39 11 - 20 14 - 26 Very Dense > 50 > 105 > 33 > 70 Hard > 30 > 39 > 20 > 26

USCS METHOD OF SOIL CLASSIFICATION

Explanation of USCS Method of Soil Classification

PROJECT NO. DATE FIGURE Explanation of Test Pit, Core, Trench and SAMPLES EXCAVATION LOG Hand Auger Log Symbols EXPLANATION SHEET U.S.C.S. DEPTH (FEET) MOISTURE (%) MOISTURE

PROJECT NO. DATE CLASSIFICATION Bulk DRY DENSITY (PCF) Driven Sand Cone Sand 0 SM FILL: Bulk sample.

ML Dashed line denotes material change. Drive sample. 1 Sand cone performed. Seepage Groundwater encountered during excavation.

No recovery with drive sampler. 2 Groundwater encountered after excavation. Sample retained by others.

Shelby tube sample. Distance pushed in inches/length of sample xx/xx recovered in inches 3

No recovery with Shelby tube sampler. SM ALLUVIUM: Solid line denotes unit change. Attitude: Strike/Dip b: Bedding 4 c: Contact j: Joint f: Fracture F:Fault cs: Clay Seam s: Shear 5 bss: Basal Slide Surface sf: Shear Fracture FIGURE sz: Shear Zone sbs: Sheared Bedding Surface The total depth line is a solid line that is drawn at the bottom of the excavation log. SCALE: 1 inch = 1 foot

Testpit explanation.xls DATE DRILLED 2/25/09 BORING NO. B-1

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 2

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

SC ALLUVIUM: Reddish brown, damp to moist, medium dense, clayey SAND.

89 16.0 117.0 Moist; very dense.

10 67/9" Reddish brown to olive brown; saturated.

GRANITIC ROCK: Brown to dark brown (mottled), saturated, fine- to coarse-grained GRANITIC ROCK; weathered. Difficult drilling from 13 to 15 feet. 15 50/4"

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-1 DATE DRILLED 2/25/09 BORING NO. B-1

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 2 OF 2

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT 140 lbs. (Cathead) DROP 30" BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY TMG LOGGED BY TMG REVIEWED BY RI DESCRIPTION/INTERPRETATION 20 GRANITIC ROCK: (Continued) Gray to dark gray, moist to wet, fine- to coarse-grained GRANITIC ROCK; weathered. Total Depth = 21 feet. Groundwater encountered at a depth of approximately 10.5 feet during drilling. Backfilled with approximately 7 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

40 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-2 DATE DRILLED 2/27/09 BORING NO. B-2

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT 140 lbs. (Cathead) DROP 30" BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY BTM LOGGED BY BTM REVIEWED BY RI DESCRIPTION/INTERPRETATION 0 SC ALLUVIUM: Reddish brown, damp to moist, medium dense, clayey SAND.

Harder drilling.

Scattered gravel.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-3 DATE DRILLED 2/27/09 BORING NO. B-3

SAMPLES GROUND ELEVATION 379'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

5 GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-4 DATE DRILLED 2/27/09 BORING NO. B-4

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

5 GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-5 DATE DRILLED 2/27/09 BORING NO. B-5

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Difficult drilling. 5 GRANITIC ROCK: Brown, damp, GRANITIC ROCK; weathered. Auger refusal on granitic rock. Total Depth = 6.5 feet. Groundwater not encountered during drilling. Backfilled with approximately 2 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report. 10 The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is not sufficiently accurate for preparing construction bids and design documents.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-6 DATE DRILLED 2/27/09 BORING NO. B-6

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Harder drilling.

Damp.

GRANITIC ROCK: Brown, damp, GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-7 DATE DRILLED 2/27/09 BORING NO. B-7

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-8 DATE DRILLED 2/26/09 BORING NO. B-8

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Hard drilling.

5 GRANITIC ROCK: 50/6" Brown to light brown to reddish brown to black (mottled), damp, fine- to coarse-grained GRANITIC ROCK; weathered; crumbles; pieces of quartz and mica.

79/11" Hard drilling.

15 50/6" Total Depth = 15.5 feet. (Refusal) Groundwater not encountered during drilling. Backfilled with approximately 5.2 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is not sufficiently accurate for preparing construction bids and design documents. 20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-9 DATE DRILLED 2/26/09 BORING NO. B-9

SAMPLES GROUND ELEVATION 379'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

5 50/5" Very dense. GRANITIC ROCK: Reddish brown to brown, damp, fine- to coarse-grained GRANITIC ROCK; weathered.

10 50/6"

15 50/6" Coarser-grained. Total Depth = 16 feet. Groundwater encountered at a depth of approximately 8.5 feet after drilling. Backfilled with approximately 5.6 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is 20 not sufficiently accurate for preparing construction bids and design documents. BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-10 DATE DRILLED 2/27/09 BORING NO. B-10

SAMPLES GROUND ELEVATION 379'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered.

Auger refusal on granitic rock, 5 Total Depth = 5 feet. Groundwater not encountered during drilling. Backfilled with approximately 1.8 cubic feet of bentonite grout shortly after drilling on 2/ 27/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-11 DATE DRILLED 2/25/09 BORING NO. B-11

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Brown, damp, fine- to coarse-grained GRANITIC ROCK; weathered. 10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-12 DATE DRILLED 2/26/09 BORING NO. B-12

SAMPLES GROUND ELEVATION 382'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: reddish brown to olive brown to black to very light brown (mottled), damp, fine- to coarse-grained GRANITIC ROCK; weathered.

75/10" 12.5 115.3 Moist.

50/4" Total Depth = 8.3 feet. Groundwater not encountered during drilling. Backfilled with approximately 2.8 cubic feet of bentonite grout shortly after drilling on 2/26/09. 10 Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-13 DATE DRILLED 2/26/09 BORING NO. B-13

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Hard drilling. GRANITIC ROCK: Reddish brown to brown to black (mottled), moist, fine- to coarse-grained GRANITIC ROCK; weathered.

5 50/6" 12.1 119.5

79/11"

Total Depth = 9.4 feet. (Auger Refusal) 10 Groundwater not encountered during drilling. Backfilled with approximately 2.8 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-14 DATE DRILLED 2/25/09 BORING NO. B-14

SAMPLES GROUND ELEVATION 382'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Brown, damp, fine- to coarse-grained GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-15 DATE DRILLED 2/25/09 BORING NO. B-15

SAMPLES GROUND ELEVATION 382'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Brown, damp, fine- to coarse-grained GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-16 DATE DRILLED 2/26/09 BORING NO. B-16

SAMPLES GROUND ELEVATION 384'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Hard drilling at 2 feet.

5 GRANITIC ROCK: Reddish brown to brown (mottled), damp, GRANITIC ROCK. 34

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-17 DATE DRILLED 2/26/09 BORING NO. B-17

SAMPLES GROUND ELEVATION 385'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Reddish brown to brown to light brown to black (mottled), damp, fine- to coarse-grained 5 GRANITIC ROCK; weathered. 50/5"

50/6" 13.4 122.1 Moist. Total Depth = 9.5 feet. (Auger Refusal) 10 Groundwater not encountered during drilling. Backfilled with approximately 3 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-18 DATE DRILLED 2/25/09 BORING NO. B-18

SAMPLES GROUND ELEVATION 384'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Gravel.

GRANITIC ROCK: Brown, damp, GRANITIC ROCK; weathered 10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-19 DATE DRILLED 2/25/09 BORING NO. B-19

SAMPLES GROUND ELEVATION 382'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

GRANITIC ROCK: Brown, damp, fine- to coarse-grained GRANITIC ROCK; weathered.

10 Total Depth = 10 feet. Groundwater not encountered during drilling. Backfilled with approximately 3.5 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-20 DATE DRILLED 2/26/09 BORING NO. B-20

SAMPLES GROUND ELEVATION 386'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Hard drilling at 2.5 feet.

5 82 13.2 118.5 Moist.

GRANITIC ROCK: Reddish brown to brown to black, damp, fine- to coarse-grained GRANITIC ROCK.

10 80/11"

Total Depth = 13 feet. Groundwater not encountered during drilling. Backfilled with approximately 4.5 cubic feet of bentonite grout shortly after drilling on 2/26/09.

15 Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-21 DATE DRILLED 2/25/09 BORING NO. B-21

SAMPLES GROUND ELEVATION 387'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Total Depth = 7 feet. Groundwater not encountered during drilling. Backfilled with approximately 2.4 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in 10 the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-22 DATE DRILLED 2/26/09 BORING NO. B-22

SAMPLES GROUND ELEVATION 385'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

Very hard drilling.

5 SC Reddish brown to brown (mottled), damp, very dense, clayey SAND. 78

59 GRANITIC ROCK: Olive brown to brown to dark brown (mottled), damp, fine- to coarse-grained GRANITIC ROCK; weathered.

Total Depth = 12.5 feet. Groundwater not encountered during drilling. Backfilled with approximately 4.4 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher 15 level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-23 DATE DRILLED 2/26/09 BORING NO. B-23

SAMPLES GROUND ELEVATION 385'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

SC ALLUVIUM: Reddish brown, moist, dense, silty clayey SAND. 5 50/6" 16.0 116.4 Very dense.

GRANITIC ROCK: Reddish brown to brown to black (mottled), damp, fine- to coarse-grained GRANITIC ROCK; weathered.

15 50/5"

Total Depth = 16 feet. Groundwater encountered at a depth of approximately 12 feet during drilling. Backfilled with approximately 5.6 cubic feet of bentonite grout shortly after drilling on 2/26/09.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is 20 not sufficiently accurate for preparing construction bids and design documents. BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-24 DATE DRILLED 2/25/09 BORING NO. B-24

SAMPLES GROUND ELEVATION 385'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

5 GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered.

Total Depth = 9.5 feet. 10 Groundwater not encountered during drilling. Backfilled with approximately 3.3 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-25 DATE DRILLED 2/25/09 BORING NO. B-25

SAMPLES GROUND ELEVATION 390'  (MSL) SHEET 1 OF 2

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

5 Reddish brown and dark brown (mottled); very dense.

Hard drilling at 7 feet.

72 Dense.

GRANITIC ROCK: 15 Reddish brown to dark brown, damp, fine- to coarse-grained GRANITIC ROCK; 50/6" weathered.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-26 DATE DRILLED 2/25/09 BORING NO. B-25

SAMPLES GROUND ELEVATION 390'  (MSL) SHEET 2 OF 2

METHOD OF DRILLING 8" Diameter Hollow-Stem Auger (Ingersoll A-300) (Scott's Drilling) U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT 140 lbs. (Cathead) DROP 30" BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY TMG LOGGED BY TMG REVIEWED BY RI DESCRIPTION/INTERPRETATION 20 50/4" GRANITIC ROCK: (Continued) Dark brown to light brown (mottled), damp, coarse-grained GRANITIC ROCK; weathered. Total Depth = 20.3 feet. Groundwater not encountered during drilling. Backfilled with approximately 7 cubic feet of bentonite grout shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

25 The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is not sufficiently accurate for preparing construction bids and design documents.

40 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-27 DATE DRILLED 4/05/16 BORING NO. NM-1

SAMPLES GROUND ELEVATION 378'  (MSL) SHEET 1 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

SM ALLUVIUM: Reddish brown, moist, dense, silty SAND.

71 Very dense.

ML Light olive gray, moist, hard, sandy SILT.

10 SM Reddish brown, wet, very dense, silty SAND. 99/9" 12.0 118.7

@ 12.5' to 14.5': Scattered gravel and cobbles.

GRANITIC ROCK: 15 Reddish brown to gray, wet, GRANITIC ROCK; weathered.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-28 DATE DRILLED 4/05/16 BORING NO. NM-1

SAMPLES GROUND ELEVATION 378'  (MSL) SHEET 2 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

Total Depth = 21.3 feet. Groundwater encountered at approximately 12 feet during drilling and at approximately 10 feet approximately 4 hours after drilling. Backfilled with approximately 7.4 cubic feet of bentonite grout and concrete cap shortly after drilling on 4/05/16.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

40 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-29 DATE DRILLED 4/05/16 BORING NO. NM-2

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

SM ALLUVIUM: Reddish brown, moist, very dense, silty SAND.

27 Dense.

10 Wet; very dense.

50 28.6 94.5

GRANITIC ROCK: Light brown to gray, wet, GRANITIC ROCK; weathered. 15

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-30 DATE DRILLED 4/05/16 BORING NO. NM-2

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 2 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT 140 lbs. (Auto-Trip) DROP 30" BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY BTM LOGGED BY BTM REVIEWED BY JMM DESCRIPTION/INTERPRETATION 20 GRANITIC ROCK: (Continued) 50/6" Light gray, wet, GRANITIC ROCK; weathered. Total Depth = 21 feet. Groundwater encountered at approximately 19 feet during drilling and at approximately 10.2 feet approximately 3 hours after drilling. Backfilled with approximately 7.4 cubic feet of bentonite grout and concrete cap shortly after drilling on 4/05/16.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

The ground elevation shown above is an estimation only. It is based on our interpretations 25 of published maps and other documents reviewed for the purposes of this evaluation. It is not sufficiently accurate for preparing construction bids and design documents.

40 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-31 DATE DRILLED 4/05/16 BORING NO. NM-3

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 1 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

SM ALLUVIUM: Brown, moist, very dense, silty SAND.

ML Light brown, moist, hard, sandy SILT. 35

SM Brown, wet, dense, silty SAND.

65 15.1 106.4

50/6" GRANITIC ROCK: Light brown to gray, wet, GRANITC ROCK; weathered.

15 50/4" Gray.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-32 DATE DRILLED 4/05/16 BORING NO. NM-3

SAMPLES GROUND ELEVATION 380'  (MSL) SHEET 2 OF 2

METHOD OF DRILLING 6" Diameter Hollow Stem Auger (Diedrich 120AT) (Tri-Country) U.S.C.S. SYMBOL

Total Depth = 21.5 feet. Groundwater encountered at approximately 18 feet during drilling and at approximately 10.3 feet approximately 2.25 hours after drilling. Backfilled with approximately 7.4 cubic feet of bentonite grout and concrete cap shortly after drilling on 4/05/16.

Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report. 25 The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the purposes of this evaluation. It is not sufficiently accurate for preparing construction bids and design documents.

40 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-33 DATE DRILLED 2/25/09 BORING NO. PT-1

SAMPLES GROUND ELEVATION 378'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Solid-Stem Auger U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT N/A DROP N/A BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY TMG LOGGED BY TMG REVIEWED BY RI DESCRIPTION/INTERPRETATION 0 SM ALLUVIUM: Reddish brown, damp, medium dense, silty SAND.

Total Depth = 6 feet. Groundwater not encountered during drilling. Backfilled shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-34 DATE DRILLED 2/25/09 BORING NO. PT-2

SAMPLES GROUND ELEVATION 381'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Solid-Stem Auger U.S.C.S. SYMBOL

Total Depth = 3 feet. Groundwater not encountered during drilling. Backfilled shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher 5 level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-35 DATE DRILLED 2/25/09 BORING NO. PT-3

SAMPLES GROUND ELEVATION 388'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Solid-Stem Auger U.S.C.S. SYMBOL

Total Depth = 3 feet. Groundwater not encountered during drilling. Backfilled shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher 5 level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-36 DATE DRILLED 2/25/09 BORING NO. PT-4

SAMPLES GROUND ELEVATION 385'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Solid-Stem Auger U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT N/A DROP N/A BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY TMG LOGGED BY TMG REVIEWED BY RI DESCRIPTION/INTERPRETATION 0 SC ALLUVIUM: Reddish brown, damp, medium dense, clayey fine SAND.

Light reddish brown.

GRANITIC ROCK: Light reddish brown, damp, GRANITIC ROCK. 5

Total Depth = 6 feet. Groundwater not encountered during drilling. Backfilled shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-37 DATE DRILLED 2/25/09 BORING NO. PT-5

SAMPLES GROUND ELEVATION 382'  (MSL) SHEET 1 OF 1

METHOD OF DRILLING 8" Diameter Solid-Stem Auger U.S.C.S. SYMBOL

DEPTH (feet) DEPTH DRIVE WEIGHT N/A DROP N/A BLOWS/FOOT MOISTURE (%) MOISTURE Bulk CLASSIFICATION Driven DRY DENSITY (PCF) SAMPLED BY TMG LOGGED BY TMG REVIEWED BY RI DESCRIPTION/INTERPRETATION 0 SC ALLUVIUM: Reddish brown, damp, medium dense, clayey SAND.

5 GRANITIC ROCK: Light brown, damp, GRANITIC ROCK; weathered. Total Depth = 6 feet. Groundwater not encountered during drilling. Backfilled shortly after drilling on 2/25/09.

Note: Groundwater, though not encountered at the time of drilling, may rise to a higher level due to seasonal variations in precipitation and several other factors as discussed in the report.

20 BORING LOG CAJON AIR CENTER AT GILLESPIE FIELD EL CAJON, CALIFORNIA PROJECT NO. DATE FIGURE 108139001 5/16 A-38 DATE EXCAVATED 4/05/16 TRENCH NO. TP-1

GROUND ELEVATION 378' (MSL) LOGGED BY BTM TRENCH LOG SAMPLES METHOD OF EXCAVATION CAT 310 Backhoe CAJON AIR CENTER AT GILLESPIE FIELD U.S.C.S. EL CAJON, CALIFORNIA LOCATION See Figure 2 DEPTH (FEET) MOISTURE (%) Bulk CLASSIFICATION PROJECT NO. DATE Driven DRY DENSITY (PCF)

Sand Cone DESCRIPTION 108139001 5/16 0 SM FILL: Reddish brown, moist, medium dense, silty SAND.

SM ALLUVIUM: Reddish brown, moist, dense, silty SAND.

8 Wet.

Very dense.

12 Total Depth = 12.5 feet. Groundwater encountered at approximately 12.3 feet during excavation; increased to a depth of approximately 9.1 feet. Backfilled on 4/5/16.

16 Note: Groundwater may rise to a level higher than that measured in borehole due to seasonal variations in precipitation and several other factors as discussed in the report.

The ground elevation shown above is an estimation only. It is based on our interpretations of published maps and other documents reviewed for the 20 purposes of this evaluation. It is not sufficiently accurate for preparing

FIGURE A-39 construction bids and design documents.

24 SCALE = 1 in./4 ft. Cajon Air Center at Gillespie Field May 11, 2016 El Cajon, California Project No. 10813001

APPENDIX B

GEOTECHNICAL LABORATORY TESTING

Classification Soils were visually and texturally classified in accordance with the Unified Soil Classification System (USCS) in general accordance with ASTM D 2488. Soil classifications are indicated on the logs of the exploratory excavations in Appendix A.

In-Place Moisture and Density Tests The moisture content and dry density of relatively undisturbed samples obtained from the exploratory excavations were evaluated in general accordance with ASTM D 2937. The test results are presented on the logs of the exploratory excavations in Appendix A.

Gradation Analysis Gradation analysis tests were performed on selected representative soil samples in general accordance with ASTM D 422. The grain-size distribution curves are shown on Figures B-1 through B-8. These test results were utilized in evaluating the soil classifications in accordance with the USCS.

200 Wash An evaluation of the percentage of particles finer than the No. 200 sieve in a selected soil sample was performed in general accordance with ASTM D 1140. The results of the test are presented on Figure B-9.

Atterberg Limits Tests were performed on selected representative fine-grained soil samples to evaluate the liquid limit, plastic limit, and plasticity index in general accordance with ASTM D 4318. These test results were utilized to evaluate the soil classification in accordance with the USCS. The test results and classifications are shown on Figure B-10.

Direct Shear Test Direct shear tests were performed on relatively undisturbed samples in general accordance with ASTM D 3080 to evaluate the shear strength characteristics of selected materials. The samples were inundated during shearing to represent adverse field conditions. The results are shown on Figures B-11 and B-12.

Cajon Air Center at Gillespie Field May 11, 2016 El Cajon, California Project No. 108139001

Expansion Index Test The expansion index of a selected material was evaluated in general accordance with ASTM D 4829. The specimen was molded under a specified compactive energy at approximately 50 percent saturation. The prepared 1-inch thick by 4-inch diameter specimen was loaded with a surcharge of 144 pounds per square foot and was inundated with tap water. Readings of volumetric swell were made for a period of 24 hours. The results of the test are presented on Figure B-13.

California Bearing Ratio (CBR) CBR tests were performed on selected representative soil samples in general accordance with ASTM D 1883. Specimens were molded under specified amounts of compactive energy up to approximately 100 percent of maximum laboratory density at optimum moisture content. The specimens were soaked for at least 96 hours and then tested to evaluate the penetration resistance of a piston moving at a rate of 0.05 inch per minute. The CBR values shown on Figures B-14 through B-19 are a ratio of penetration resistance at 0.1 inch of penetration to the standard penetration resistance value.

Soil Corrosivity Tests Soil pH, and resistivity tests were performed on representative samples in general accordance with California Test (CT) 643. The soluble sulfate and chloride content of selected samples were evaluated in general accordance with CT 417 and CT 422, respectively. The test results are presented on Figure B-20.

108139001 R Revised.doc 2 GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER FINER BY WEIGHT PERCENT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Equivalent Symbol D D D C C Location (ft) Limit Limit Index 10 30 60 u c No. 200 USCS (%)

B-16 5.0-6.5 ------27 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-1 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE B-16 @ 5.0-6.5.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER BY WEIGHT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-1 1.0-5.0 ------36 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-2 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-1 @ 1.0-5.0.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER BY WEIGHT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-1 10.0-11.3 ------13 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-3 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-1 @ 10.0-11.3.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER BY WEIGHT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-2 1.0-5.0 ------38 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-4 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-2 @ 1.0-5.0.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER BY WEIGHT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-2 10.0-11.5 ------16 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-5 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-2 @ 10.0-11.5.xls GRAVEL SAND FINES Coarse Fine CoarseMedium Fine Silt Clay

U.S. STANDARD SIEVE NUMBERS HYDROMETER 3" 1-1/2" 1" 3/4" 1/2" 3/8" 4 8 16 30 50 100 200 100

30 PERCENT FINERWEIGHT BY

0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C U.S.C.S Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-3 1.0-2.0 ------35 SC

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-6 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-3 @ 1.0-2.0.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER BY WEIGHT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

NM-3 10.0-11.5 ------34 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-7 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE NM-3 @ 10.0-11.5.xls GRAVEL SAND FINES Coarse Fine Coarse MediumFine SILT CLAY

U.S. STANDARD SIEVE NUMBERS HYDROMETER

3" 2" 1½" 1" ¾" ½" ⅜" 4 816 3050100 200 100.0

90.0

80.0

70.0

60.0

50.0

40.0

30.0 PERCENT FINER FINER BY WEIGHT PERCENT 20.0

10.0

0.0 100 10 1 0.1 0.01 0.001 0.0001

GRAIN SIZE IN MILLIMETERS

Sample Depth Liquid Plastic Plasticity Passing Symbol D D D C C USCS Location (ft) Limit Limit Index 10 30 60 u c No. 200 (%)

PT-5 1.0-6.0 ------33 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 422

GRADATION TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-8 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SIEVE PT-5 @ 1.0-6.0.xls

SAMPLE PERCENT PERCENT USCS SAMPLE DEPTH DESCRIPTIONPASSING PASSING (TOTAL LOCATION (FT) NO. 4 NO. 200 SAMPLE)

B-3 0.0-5.0 Clayey SAND 100 48 SC

B-7 0.0-5.0 Silty SAND 99 42 SM

B-9 5.0-5.4 Silty SAND 100 17 SM

B-14 0.0-5.0 Clayey SAND 92 29 SC

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 1140

NO. 200 SIEVE ANALYSIS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-9 108139001 5/16 EL CAJON, CALIFORNIA

108139001, 200 WASH Page 1.xls USCS SYMBOL LOCATION DEPTH LIQUID PLASTIC PLASTICITY CLASSIFICATION USCS (FT) LIMIT, LL LIMIT, PL INDEX, PI (Fraction Finer Than (Entire Sample) No. 40 Sieve) B-2 0.0-5.032 18 14 CL SC

B-4 0.0-5.028 18 10 CL SC

 B-17 0.0-3.5 29 26 3 ML SM

B-22 0.0-5.0 22 19 3 ML SM

NP - INDICATES NON-PLASTIC

50 CH or OH 40

20 CL or OL MH or OH PLASTICITY INDEX, PI PLASTICITY INDEX, PI

10 ML or OL CL - ML

0 0 102030405060708090100

LIQUID LIMIT, LL

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 4318-05

ATTERBERG LIMITS TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD 108139001 5/16 B-10 EL CAJON, CALIFORNIA

108139001 ATTERBERG Page 1.xls 3000

2000

1000 SHEAR STRESS (PSF) STRESS SHEAR

0 0 1000 2000 3000 NORMAL STRESS (PSF)

Sample Depth Shear Cohesion, c Friction Angle,  Description Symbol Soil Type Location (ft) Strength (psf) (degrees)

Clayey SAND B-205.0-6.0 Peak710 32 SC

Clayey SAND X B-20 5.0-6.0 Ultimate 170 32 SC

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 3080

DIRECT SHEAR TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-11 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SHEAR B-20 @ 5.0-6.0.xls 5000

4000

3000

2000 SHEAR STRESS (PSF)

1000

0 0 1000 2000 3000 4000 5000 NORMAL STRESS (PSF)

Sample Depth Shear Cohesion, c Friction Angle,  Description Symbol Soil Type Location (ft) Strength (psf) (degrees)

Silty SAND NM-210.0-11.5 Peak 140 39 SM

Silty SAND X NM-2 10.0-11.5 Ultimate 80 30 SM

PERFORMED IN GENERAL ACCORDANCE WITH ASTM D 3080

DIRECT SHEAR TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-12 108139001 5/16 EL CAJON, CALIFORNIA

108139001 SHEAR NM-2 @ 10.0-11.5.xls

SAMPLE SAMPLE INITIAL COMPACTED FINAL VOLUMETRIC EXPANSION POTENTIAL LOCATION DEPTH MOISTURE DRY DENSITY MOISTURE SWELL INDEX EXPANSION (FT) (%) (PCF) (%) (IN) B-6 0.0-5.0 9.0 113.8 18.1 0.025 25 Low

PERFORMED IN GENERAL ACCORDANCE WITH UBC STANDARD 18-2 ASTM D 4829

EXPANSION INDEX TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-13 108139001 5/16 EL CAJON, CALIFORNIA

108139001 EI Page 1.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Clayey SAND 0.0-5.0 & 0.0-5.0 SC B-6 & B-11

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-14 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-6 & B-11.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Clayey SAND 0.0-5.0 & 0.0-7.0 SC B-7 & B-14

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-15 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-7 & B-14.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Silty SAND 0.0-4.0 & 0.0-3.5 SM B-15 & B-17

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-16 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-15 & B-17.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Clayey SAND 0.0-4.0 & 1.0-4.0 SC B-16 & PT-4

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-17 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-16 & PT-4.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Clayey SAND 0.0-5.0 & 0.0-4.0 SC B-20 & B-21

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-18 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-20 & B-21.xls DRY DENSITY vs CBR

CORRECTED CBR CORRECTED 10

0 100.0 110.0 120.0 130.0 140.0

DRY DENSITY (PCF)

Depth Description Symbol Sample Location Soil Type (ft) Composite Silty SAND 0.0-4.0 & 1.0-5.0 SM B-23 & B-24

CBR TEST RESULTS FIGURE PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-19 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CBR @ B-23 & B-24.xls CHLORIDE SAMPLE SAMPLE DEPTH RESISTIVITY 1 SULFATE CONTENT 2 pH 1 CONTENT 3 LOCATION (FT) (Ohm-cm) (ppm) (%) (ppm)

B-3 0.0-5.0 6.3 1,600 20 0.002 390

B-18 0.0-4.06.6 2,500 20 0.002 230

B-23 0.0-4.0 7.3 2,000 20 0.002 400

NM-2 1.0-5.0 7.8 1,000 1,100 0.110 215

1 PERFORMED IN GENERAL ACCORDANCE WITH CALIFORNIA TEST METHOD 643 2 PERFORMED IN GENERAL ACCORDANCE WITH CALIFORNIA TEST METHOD 417 3 PERFORMED IN GENERAL ACCORDANCE WITH CALIFORNIA TEST METHOD 422

CORROSIVITY TEST RESULTS FIGURE

PROJECT NO. DATE CAJON AIR CENTER AT GILLESPIE FIELD B-20 108139001 5/16 EL CAJON, CALIFORNIA

108139001 CORROSIVITY Page 1.xls