79-4 Geotech Report.pdf

REPORT C OVER PAGE

Geotechnical Engineering Report

Basins F with Amenities and Basin G

Visalia, Tulare County, California

April 1, 2020

Terracon Project No. 60205037

Prepared for:

Fullerton, California

Prepared by:

Terracon Consultants, Inc.

Tustin, California

Terracon Consultants, Inc. 1421 Edinger Ave Sui te C Tustin, California 92780

P [949] 261 0051 F [949] 261 6110 terracon.com

REPORT C OVER LETTER TO SIGN

1561 E. Orangethorpe Avenue

Fullerton, California 92831

Attn: Mr. William Young

P: (714) 526-7500 x103

E: wyoung@cwecorp.com

Re: Geotechnical Engineering Report

Basins F with Amenities and Basin G

Mineral King Avenue and 5th Avenue E

Visalia, Tulare County, California

Terracon Project No. 60205037

Dear Mr. Young:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with CWE Work Order 20358W04As and

20359W04As for Basins F and G, respectively, dated February 14, 2020. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Victor V. Nguyen, E.I.T. Sivasubramaniam (Raj) Pirathiviraj, P.E., G.E.

Staff Engineer Senior Geotechnical Engineer

APR review provided by F. Fred Buhamdan, P.E.

12/31/21

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

SEISMIC CONSIDERATIONS

LIQUEFACTION

CORROSIVITY

STORMWATER MANAGEMENT

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

LATERAL EARTH PRESSURES

PAVEMENTS

GENERAL COMMENTS

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS (Boring Logs and Laboratory Data)

SUPPORTING INFORMATION (General Notes and Unified Soil Classification System)

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INTRODUCTION

Geotechnical Engineering Report

Basins F with Amenities and Basin G

Mineral King Avenue and 5th Avenue E

Visalia, Tulare County, California Terracon Project No. 60205037

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed East Side Regional Park Basins G and F with Amenities project to be located at the northwest corner of the intersection of Mineral King Avenue and 5th

Avenue E in Visalia, Tulare County, California. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Foundation design and construction

■ Groundwater conditions ■ Seismic site classification per CBC

■ Site preparation and earthwork ■ Pavement design and construction

■ Infiltration Design and Considerations

The geotechnical engineering Scope of Services for this project included the advancement of eight (8) test borings to depths ranging from approximately 26½ to 71½ feet below existing site grades. Four (4) of these borings were utilized for percolation testing.

Maps showing the site and boring locations with approximate limits of Basins G and F are shown in the Site Location and Exploration Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs and as separate graphs in the Exploration Results section.

SITE CONDITIONS

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Item Description

Parcel Information

The project is located at the northwest corner of Mineral King Avenue and 5th

Avenue E in Visalia, Tulare County, California.

Approximate coordinates for the center of the sites are as follows:

Basin F: 36.3296°N, 119.2380°W

Basin G: 36.3288°N, 119.2360°W

Basins F with Amenities and Basin G ■ Visalia, Tulare County, California

April 1, 2020 ■ Terracon Project No. 60205037

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Item Description

Existing

Improvements

The proposed basins are separated by Packwood Creek and both basins are currently used as fruit tree orchards.

Current Ground

Cover

Basin F is covered by exposed soil and rows of trees. Basin G is covered by exposed soils, rows of trees, dead shrubs and vegetation.

Existing Topography

Based on our review of a topographic map for the project site, Basin F, located north of Packwood Creek has an existing ground surface elevation between

348 and 351 feet above mean-sea-level (MSL) with a gentle slope descending towards west.

Basin G is located south of Packwood Creek. Elevations on Basin G are split between the area containing rows of trees on the north portion of Basin G and the dirt lot containing exposed soils, dead shrubs and vegetation on the southern portion. The north portion has an existing ground surface elevation between 348 and 349 feet MSL and is relatively flat. The southern portion has an elevation of approximately 344 feet MSL and surrounded by ascending slopes. These ascending slopes are approximately 4 feet high.

Geology

The site is situated within the middle-eastern Great Valley Geomorphic

Province in Central California. This province is characterized by an alluvial plain approximately 50 miles wide and 400 miles long in the central portion of

California. It is bounded by the Sierra Nevada Mountains to the east and the

Coast Ranges to the west. This portion of the Great Valley is drained by the

San Joaquin River, which is the primary source of the alluvial deposits in this province. 1, 2 Surficial geologic units mapped at the site consists of Quaternary age recent fan deposits. 3

Pavement

It is our understanding that new pavements will be constructed and are included in this project. Asphalt and aggregate surface pavement sections have been considered. Anticipated traffic is as follows:

■ Light Automobile Parking: Traffic Index of 4.5

■ On-site driveways: Traffic Index of 5.5

1 Harden, D. R., “California Geology, Second Edition,” Pearson Prentice Hall, 2004.

2 Norris, R. M. and Webb, R. W., “Geology of California, Second Edition,” John Wiley & Sons, Inc., 1990.

3 State of California – Division of Mines and Geology, Geologic Map of California, Olaf P. Jenkins Edition, Fresno Sheet, Compilation by Robert A. Matthews and John L. Burnett in 1965, Second Printing, 1975.

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PROJECT DESCRIPTION

Item Description

Proposed Structures

The project includes the construction of two new groundwater recharge basins, designated as Basins G and F with recreational amenities. A series of dry wells are proposed within both basins and these dry wells are anticipated to be installed to the depth of about 45 feet below existing ground surface.

The oher amenities include two pedestrian bridges located at the Packwood

Creek crossing near the east and west project limits and an outdoor recreational area which includes decomposed granite walking trails, circuit exercise stations, and disc golf field.

Construction It is anticipated that both pedestrian bridges will be single-span prefabricated structures. Both abutments will be supported on shallow foundation system.

Maximum Loads

(assumed)

■ Pedestrian bridge abutments – bearing demand of 2,000 psf

Grading Minimal cut/fill – assumed to be less than one foot

Infiltration Systems Based on the information provided by client, retention/infiltration systems consisting of series of dry wells are proposed onsite.

GEOTECHNICAL CHARACTERIZATION

We have developed a general characterization of the subsurface soil and groundwater conditions based upon our review of the data and our understanding of the geologic setting and planned construction. The following table provides our geotechnical characterization.

The geotechnical characterization forms the basis of our geotechnical calculations and evaluation of site preparation, foundation options and pavement options. As noted in General Comments, the characterization is based upon widely spaced exploration points across the site, and variations are likely. Cross sections of the soil profile (Soil Profile Sections A-A’ and B-B’) illustrating approximate changes in stratification along Basins G and F are shown under Exploration

Results.

Basin F site consist of interbedded layers of loose to medium dense sand with variable amount of silty and clay, and stiff to hard lean clay and silt with varying amounts of sand to the maximum depth explored at 71.5 feet bgs.

Basin G site consists of interbedded layers of loose to dense sand with variable amount of silty and clay, and soft to hard lean clay and silt with varying amounts of sand to the maximum depth explored at 71.5 feet bgs.

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Conditions encountered at each boring location are indicated on the individual boring logs shown in the Exploration Results section and are attached to this report. Stratification boundaries on the boring logs represent the approximate location of changes in native soil types; in situ, the transition between materials may be gradual.

Lab Results

Laboratory tests were conducted on selected soil samples and the test results are presented in the Exploration Results section and on the boring logs. Atterberg limit test results indicate that the on-site soils generally have low to medium plasticity. A consolidation test indicates that the soils encountered at an approximate depth of 2.5 feet bgs have a negligible collapse or swell potential when saturated under normal footing loads of 2,000 psf. Direct Shear tests performed on samples taken at depths of 5 feet bgs indicate these soils have a cohesion of 252 and 342 psf and effective friction angle of 32° and 30°, respectively.

Groundwater

Groundwater was observed in borings B-20-1 and B-20-4 at approximate depths of 63 and 56 feet bgs, respectively. These observations represent groundwater conditions at the time of the field exploration and may not be indicative of other times, or at other locations.

In clayey soils with low permeability, the accurate determination of groundwater level may not be possible without long term observation. Long term observation after drilling could not be performed as borings were backfilled immediately upon completion due to safety concerns. Groundwater levels can best be determined by implementation of a groundwater monitoring plan.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

According to data collected from the Water Data Library for the State of California from a nearby well, located approximately 1,400 feet west of the site in State Well Number 18S25E27Q001M, groundwater levels were recorded at 51 feet bgs in October 1990.4 Furthermore, based on another well located at a distance of 1.1 miles west of the project site, the recent groundwater depth was between the depths of 60 and 81 feet during the periods of October 2011 to March

2019.

4 Groundwater elevation was obtained from the Water Data Library for the State of California Well ID 363286N1192431W001

(http://wdl.water.ca.gov/waterdatalibrary/groundwater/hydrographs/brr_hydro.cfm?CFGRIDKEY=34338).

http://wdl.water.ca.gov/waterdatalibrary/groundwater/hydrographs/brr_hydro.cfm?CFGRIDKEY=34338

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SEISMIC CONSIDERATIONS

The 2019 California Building Code (CBC) Seismic Design Parameters have been generated using the SEAOC/OSHPD Seismic Design Maps Tool. This web-based software application calculates seismic design parameters in accordance with ASCE 7-16 and 2019 CBC. The 2019 CBC requires that a site-specific ground motion study be performed in accordance with Section 11.4.8 of ASCE 7-16 for Site Class D sites with a mapped S1 value greater than or equal 0.2.

However, Section 11.4.8 of ASCE 7-16 includes an exception from such analysis for specific structures on Site Class D sites. The commentary for Section 11 of ASCE 7-16 (Page 534 of

Section C11 of ASCE 7-16) states that “In general, this exception effectively limits the requirements for site-specific hazard analysis to very tall and or flexible structures at Site Class

D sites.” Based on our understanding of the proposed structures, it is our assumption that the exception in Section 11.8.4 applies to the proposed structure. However, the structural engineer should verify the applicability of this exception.

Based on this exception, the spectral response accelerations presented below were calculated using the site coefficients (Fa and Fv) from Tables 1613.2.3(1) and 1613.2.3(2) presented in

Section 16.4.4 of the 2019 CBC.

Description Value

2019 California Building Code Site Classification (CBC) D

Site Latitude (°N) 36.3296

Site Longitude (°W) 119.2380

Ss Spectral Acceleration for a 0.2-Second Period 0.526 (From OSHPD Seismic Maps)

S1 Spectral Acceleration for a 1-Second Period 0.212 (From OSHPD Seismic Maps)

Fa Site Coefficient for a 0.2-Second Period 1.379 (Calculate based on CBC PDF)

Fv Site Coefficient for a 1-Second Period 2.176 (Calculate based on CBC PDF)

1. Seismic site classification in general accordance with the 2019 California Building Code.

2. The 2019 California Building Code (CBC) requires a site soil profile determination extending to a depth of

100 feet for seismic site classification. The current scope does not include the required 100-foot soil profile determination. Borings were extended to a maximum depth of 71½ feet, and this seismic site class definition considers that similar or denser soils continue below the maximum depth of the subsurface exploration.

Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration.

A site-specific ground motion study may reduce design values and consequently construction costs. We recommend consulting with a structural engineer to evaluate the need for such study and its potential impact on construction costs. Terracon should be contacted if a site-specific ground motion study is desired.

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Faulting and Estimated Ground Motions

The site is located in the central California, which is a seismically active area. The type and magnitude of seismic hazards affecting the site are dependent on the distance to causative faults, the intensity, and the magnitude of the seismic event. As calculated using the USGS Unified

Hazard Tool, the fault, which is considered to have the most significant effect at the site from a design standpoint, has a maximum credible earthquake magnitude of 5.67 and is located approximately 6.71 kilometers from the site. Furthermore, the San Andreas and Great Valley faults are located at a distance of approximately 115 and 75 kilometers, respectively, from the project site and these faults are capable of generating Magnitude 8.1 and 7.42 earthquakes, respectively.

Based on the USGS Design Maps Summary Report, using the American Society of Civil

Engineers (ASCE 7-16) standard, the peak ground acceleration (PGAM) at the project site is expected to be 0.313 g. Based on the USGS Unified Hazard Tool, the project site has a mode magnitude of 5.3. Furthermore, the site is not located within an Alquist-Priolo Earthquake Fault

Zone based on our review of the State Fault Hazard Maps.5

LIQUEFACTION

Liquefaction is a mode of ground failure that results from the generation of high pore-water pressures during earthquake ground shaking, causing loss of shear strength. Liquefaction is typically a hazard where loose sandy soils exist below groundwater. The California Geological

Survey (CGS) has designated certain areas as potential liquefaction hazard zones. These are areas considered at a risk of liquefaction-related ground failure during a seismic event, based upon mapped surficial deposits and the presence of a relatively shallow water table.

The project site is not evaluated for liquefaction hazard by the CGS. However, based on data from nearby wells, the highest groundwater depth reported in the vicinity of the project site is recorded at 51 feet bgs. Liquefaction evaluation was performed in borings B-20-1 and B-20-4.

Liquefaction analyses for the site were performed in general accordance with the DMG Special

Publication 117. The liquefaction study utilized the software “LiquefyPro” by CivilTech Software.

This analysis was based on the soil data from the soil borings. A Peak Ground Acceleration

(PGA) of 0.313g and the mode magnitude of 5.3 for the project site were used. Calculations utilized the historical high groundwater depth based on the available data. Settlement analyses

5 California Department of Conservation Division of Mines and Geology (CDMG), “Digital Images of Official Maps of Alquist-Priolo

Earthquake Fault Zones of California, Southern Region”, CDMG Compact Disc 2000-003, 2000.

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Based on the analyses, liquefaction hazard potential at the site is considered low. Other geologic hazards related to liquefaction, such as lateral spreading, are therefore also considered low.

CORROSIVITY

The table below lists the results of laboratory soluble sulfate, soluble chloride, electrical resistivity, and pH testing. The values may be used to estimate potential corrosive characteristics of the on-site soils with respect to contact with the various underground materials which will be used for project construction.

Corrosivity Test Results Summary

Boring

Sample

Depth

(ft)

Soil

Description

Soluble

Sulfate

Sulfides

(ppm)

Chlorides

(ppm)

Red-Ox

Potential

(mV)

Electrical

Resistivity

(Ω-cm)

Total

Salts

(ppm) pH

B-20-1 0-5.0 Silty Sand 0.01 Nil 25 +681 2,910 537 7.70

B-20-4 0-5.0 Silty Sand 0.01 Nil 23 +675 13,095 86 8.28

Results of soluble sulfate testing indicate samples of the on-site soils tested possess negligible sulfate concentrations when classified in accordance with Table 19.3.1.1 of the ACI Design

Manual. Concrete should be designed in accordance with the exposure class S0 provisions of the

ACI Design Manual, Section 318, Chapter 19.

STORMWATER MANAGEMENT

Four (4) in-situ percolation tests were performed at approximate depths of 35 to 45 feet bgs. A 2-inch thick layer of gravel was placed in the bottom of each boring after the borings were drilled to investigate the soil profile. A 3-inch diameter perforated pipe was installed on top of the gravel layer in each boring. Gravel was used to backfill between the perforated pipes and the boring sidewall. The borings were then filled with water for a pre-soak period of 24 hours. Testing began after a pre-soak period. At the beginning of the test, the pipes were refilled with water and readings were taken at standardized time intervals. Percolation rates are provided in the following table:

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TEST RESULTS

Test Location

(depth, feet bgs) Soil Classification

Slowest Measured

Percolation Rate

(in/hr.)

Correlated

Infiltration Rate1

(in/hr.)

Water Head

(in)

P-1 (35 to 45 ft)

Very Stiff Lean Clay with variable amounts of Sand

48 0.7 128

P-2 (35 to 45 ft)

Medium Dense Sand with variable amounts of Silt

24 0.5 118

P-3 (35 to 45 ft)

Medium Dense Sand with variable amounts of Silt

153 2.9 114

P-4 (35 to 45 ft)

Medium Dense Sand with variable amounts of Silt

36 0.6 121

1. If proposed infiltration system will mainly rely on vertical downward seepage, the correlated infiltration rates should be used. The infiltration rates were correlated using the Porchet method.

With time, the bottoms of infiltration systems tend to plug with organics, sediments, and other debris. Long term maintenance will likely be required to remove these deleterious materials to help reduce decreases in actual percolation rates.

The percolation tests were performed with clear water, whereas the storm water will likely not be clear, but may contain organics, fines, and grease/oil. The presence of these deleterious materials will tend to decrease the rate that water percolates from the infiltration systems. Design of the stormwater infiltration systems should account for the presence of these materials and should incorporate structures/devices to remove these deleterious materials. A safety factor should be applied to these measured rates.

Based on the soils encountered in our borings, we expect the percolation rates of the soils could be different than measured in the field due to variations in fines and gravel content. The design elevation and size of the proposed infiltration system should account for this expected variability in infiltration rates.

Infiltration testing should be performed after construction of the infiltration system to verify the design infiltration rates. It should be noted that siltation and vegetation growth along with other factors may affect the infiltration rates of the infiltration areas. The actual infiltration rate may vary from the values reported here. Infiltration systems should be located a minimum of 10 feet from any existing or proposed foundation system.

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GEOTECHNICAL OVERVIEW

The site appears suitable for the proposed construction based upon geotechnical conditions encountered in the test borings, provided that the recommendations provided in this report are implemented in the design and construction phases of this project.

The proposed pedestrian bridges are anticipated to be a single-span prefabricated bridge. The bridge abutments may be supported by a shallow foundation system. Due to the low bearing capacity of the near surface soils, the foundation system should bear on engineered fill. Engineered fill should extend to a minimum depth of 3 feet below the bottom of foundations. Grading for the proposed footings should incorporate the limits of the foundations plus a lateral distance of 3 feet beyond the outside edge of perimeter footings. The onsite soils are considered suitable to be used as engineered fill materials.

The recommendations contained in this report are based upon the results of field and laboratory testing (presented in the Exploration Results section), engineering analyses, and our current understanding of the proposed project.

The General Comments section provides an understanding of the report limitations.

EARTHWORK

The following recommendations include site preparation, excavation, subgrade preparation and placement of engineered fills on the project. The recommendations presented for design and construction of earth supported elements including foundations and pavements are contingent upon following the recommendations outlined in this section.

Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project.

Site Preparation

Strip and remove existing vegetation, debris, trees, and other deleterious materials from proposed abutment foundations and pavement areas. Exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. The site should be initially graded to create a relatively level surface to receive fill and provide for a relatively uniform thickness of fill beneath proposed building structures.

We recommend stripping topsoil to depths that expose soils with less than 3 percent organics and no roots having a diameter greater than 1/8 inch. While the depth of the unsuitable soils should

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12 inches in light vegetation areas, and up to 48 inches within the orchards for construction budgeting purposes. The thickness of the top soil layer was not determined during our field exploration. Therefore, the actual depth of stripping should be verified by engineering observations made during the grading operations at the project. Exposed surfaces should be free of mounds and depressions which could prevent uniform compaction.

Stripped materials consisting of vegetation and organic materials should be wasted from the site or used to revegetate landscaped areas or exposed slopes after completion of grading operations.

If it is necessary to dispose of organic materials on site, they should be placed in non-structural areas, and in fill sections not exceeding 5 feet in height.

Although no evidence of fills or underground facilities such as septic tanks, cesspools, basements, and utilities was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed, and the excavation thoroughly cleaned prior to backfill placement and/or construction.

Subgrade Preparation

Due to the low bearing capacity of the near surface soils, pedestrian bridge abutment foundations should bear on engineered fill. Engineered fill should extend to a minimum depth 3 feet below the bottom of foundations. Grading for the proposed footings should incorporate the limits of the foundations plus a lateral distance of 3 feet beyond the outside edge of perimeter footings.

Subgrade soils beneath pavements should be scarified, moisture conditioned, and compacted to a minimum depth of 10 inches. The moisture content and compaction of subgrade soils should be maintained until pavement construction.

Exposed areas which will receive fill, once properly cleared and benched where necessary, should be scarified to a minimum depth of 10 inches, moisture conditioned, and compacted per the compaction requirements in this report.

Based upon the subsurface conditions determined from the geotechnical exploration, subgrade soils exposed during construction are anticipated to be relatively workable. However, the workability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unworkable conditions develop, workability may be improved by scarifying and drying.

Excavation

It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment.

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The bottom of excavations should be thoroughly cleaned of loose soils and disturbed materials prior to backfill placement and/or construction.

Onsite soils consist of cohesionless sandy soils. Such soils have the tendency to cave and slough during excavations. Therefore, formwork may be needed for foundation excavations.

Individual contractors are responsible for designing and constructing stable, temporary excavations. Excavations should be sloped or shored in the interest of safety following local, and federal regulations, including current OSHA excavation and trench safety standards.

Fill Materials and Placement

All fill materials should be inorganic soils free of vegetation, debris, and fragments larger than 6 inches in size. Pea gravel or other similar non-cementatious, poorly-graded materials should not be used as fill or backfill without the prior approval of the geotechnical engineer.

On-site soils or approved imported materials may be used as fill material for the following:

◼ general site grading ◼ foundation backfill

◼ foundation areas ◼ pavement areas

Imported soils for use as fill material within proposed building and structure areas should conform to low volume change materials as indicated in the following specifications:

Percent Finer by Weight

Gradation (ASTM C 136)

3”

No. 4 Sieve ..................................................................................... 50-100

No. 200 Sieve ................................................................................... 10-40

◼ Liquid Limit ....................................................................... 30 (max)

◼ Plasticity Index ................................................................. 15 (max)

◼ Maximum expansion index* .............................................. 20 (max)

*ASTM D 4829

The contractor shall notify the Geotechnical Engineer of import sources sufficiently ahead of their use so that the sources can be observed and approved as to the physical characteristic of the import material. For all import material, the contractor shall also submit current verified reports from a recognized analytical laboratory indicating that the import has a "not applicable" (Class S0) potential for sulfate attack based upon current ACI criteria and is "mildly corrosive" to ferrous metal and copper. The reports shall be accompanied by a written statement from the contractor that the laboratory test results are representative of all import material that will be brought to the job.

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Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift.

Fill lifts should not exceed 10 inches loose thickness.

Compaction Requirements

Recommended compaction and moisture content criteria for engineered fill materials are as follows:

Material Type and Location

Per the Modified Proctor Test (ASTM D 1557)

Minimum Compaction

Requirement (%)

Range of Moisture Contents for Compaction Above Optimum

Minimum Maximum

On-site soils or low volume change imported fill:

Beneath foundations: 90 0% +3%

Fill greater than 5 feet in depth 95 0% +3%

Miscellaneous backfill: 90 0% +3%

Beneath pavements: 95 0% +3%

Utility Trenches*: 90 0% +3%

Bottom of excavation receiving fill: 90 0% +3%

Aggregate base (beneath pavements): 95 0% +3%

* Upper 12 inches should be compacted to 95% within pavement and structural areas. Low-volume change soils should be used in structural areas.

Grading and Drainage

Positive drainage should be provided during construction and maintained throughout the life of the development. Infiltration of water into utility trenches or foundation excavations should be prevented during construction. In areas where sidewalks or paving do not immediately adjoin the proposed bridge abutments, we recommend that protective slopes be provided with a minimum grade of approximately 5 percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls, and in utility trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration.

Utility Trenches

It is anticipated that the on-site soils and fill materials will provide suitable support for underground utilities and piping that may be installed. Any soft and/or unsuitable material encountered at the bottom of excavations should be removed and be replaced with an adequate bedding material. A non-expansive granular material with a sand equivalent greater than 30 should be used for bedding and shading of utilities, unless allowed or specified otherwise by the utility manufacturer.

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On-site materials are considered suitable for backfill of utility and pipe trenches from one foot above the top of the pipe to the final ground surface, provided the material is free of organic matter and deleterious substances.

Trench backfill should be mechanically placed and compacted as discussed earlier in this report.

Compaction of initial lifts should be accomplished with hand-operated tampers or other lightweight compactors. Where trenches are placed beneath footings, the backfill should satisfy the gradation and expansion index requirements of engineered fill discussed in this report. Flooding or jetting for placement and compaction of backfill is not recommended.

Construction Considerations

Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of pavements. Construction traffic over the completed subgrade should be avoided to the extent practical. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. If the subgrade should become desiccated, saturated, or disturbed, the affected material should be removed, or these materials should be scarified, moisture conditioned, and recompacted prior to pavement construction.

Construction Observation and Testing

The geotechnical engineer should be retained during the construction phase of the project to observe earthwork and to perform necessary tests and observations during subgrade preparation, proof-rolling, placement and compaction of controlled compacted fills, backfilling of excavations to the completed subgrade.

The exposed subgrade and each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by the Geotechnical Engineer prior to placement of additional lifts.

Each lift of fill should be tested for density and water content at a frequency of at least one test for every 2,500 square feet of compacted fill in the abutment foundation areas and 5,000 square feet in pavement areas. One density and water content test for every 50 linear feet of compacted utility trench backfill.

In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of the Geotechnical Engineer. In the event that unanticipated conditions are encountered, the

Geotechnical Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

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SHALLOW FOUNDATIONS

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations for support of the pedestrian bridge.

Shallow Foundation Design Recommendations

DESCRIPTION RECOMENDATION

Foundation Type Spread footing foundations for pedestrian bridge abutments

Bearing Material Engineered fill extending to a minimum depth of 3 feet below the bottom of foundations

Allowable Bearing Pressure 2,000 psf

Minimum Dimensions 24 inches

Minimum Embedment Depth Below Finished

Grade 18 inches

Total Estimated Settlement 1 inch

Estimated Differential Settlement ½ inch across 40 feet

Finished grade is defined as the lowest adjacent grade within five feet of the foundation for perimeter (or exterior) footings.

The allowable foundation bearing pressure applies to dead loads plus design live load conditions.

The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions. The weight of the foundation concrete below grade may be neglected in dead load computations.

Foundations should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required.

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LATERAL EARTH PRESSURES

Design Parameters

For engineered fill comprised of on-site soils above any free water surface, recommended equivalent fluid pressures for unrestrained foundation elements are:

ITEM VALUEa, b

Active Case 37 psf/ft

Passive Case 390 psf/ft

At-Rest Case 56 psf/ft

Coefficient of Friction 0.35c aNote: The values are based on on-site soils used as backfill.

bNote: Uniform, horizontal backfill, compacted to at least 90% of the ASTM D 1557 maximum dry density, rendering a maximum unit weight of 120 pcf.

cNote: The coefficient of base friction should be reduced to 0.30 when used in conjunction with passive pressure

The lateral earth pressures herein do not include any factor of safety and are not applicable for submerged soils/hydrostatic loading. Additional recommendations may be necessary if such conditions are to be included in the design.

Fill against foundation and retaining walls should be compacted to densities specified in the

Earthwork section of this report. Compaction of each lift adjacent to walls should be accomplished with hand-operated tampers or other lightweight compactors.

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PAVEMENTS

General Pavement Comments

Pavement designs are provided for the traffic conditions and pavement life conditions as noted in

Project Description and in the following sections of this report. A critical aspect of pavement performance is site preparation. Pavement designs noted in this section must be applied to the site which has been prepared as recommended in the Earthwork section.

Pavement Design Parameters

An estimated design R-Value was used to calculate the asphalt concrete pavement thickness sections and the aggregate base surface road sections. R-value testing should be completed prior to pavement construction to verify the design R-value.

Assuming the pavement subgrades will be prepared as recommended within this report, the following pavement sections should be considered minimums for this project for the traffic indices assumed in the table below. As more specific traffic information becomes available, we should be contacted to reevaluate the pavement calculations.

Aggregate Surfaced Roadway Design Recommendations

Aggregate surface roadway design was conducted in general accordance with the Army Corps of

Engineers (ACOE) Technical Manual TM-5-822, Design of Aggregate Surface Roads and Airfields

(1990). The design was based on Category I, traffic containing primarily passenger cars, panel and pickup trucks, and Road Class G (Under 70 vehicles per day). Based on the Category and Road

Class, a Design Index of 1 was utilized. Terracon should be contacted if significant changes in traffic loads or in the characteristics described are anticipated.

As a minimum, aggregate surface course should have a minimum thickness of 3 inches ( if maximum aggregate size is ¾ inch) or 4 inches (if maximum aggregate size is 1½ inches) and should be constructed over a minimum of 10 inches of scarified, moisture conditioned, and compacted native soils to 95% of the maximum dry density using ASTM D 1557. Aggregate materials should conform to the specifications of Class II aggregate base (maximum in accordance with the requirements and specifications of the State of California Department of

Transportation (Caltrans), or other approved local governing specifications. The recommended thicknesses should be measured after full compaction. The width of the roadway should extend a minimum distance of 1 foot on each side of the desired surface width.

Positive drainage should be provided during construction and maintained throughout the life of the roadways. Proposed roadway design should maintain the integrity of the road and eliminate ponding.

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Asphalt Pavement Section Thicknesses

The following table provides options for AC road sections:

Recommended Pavement Section Thickness (inches)

Light (Automobile) Parking

Assumed Traffic Index (TI) = 4.5

On-site Driveways and Delivery Areas Assumed TI = 5.5

Asphaltic Concrete 3.0-inches AC over 4-inches Class

II Aggregate Base 3.0-inches AC over 5-inches

Class II Aggregate Base

1. All materials should meet the CALTRANS Standard Specifications for Highway Construction.

These pavement sections are considered minimal sections based upon the expected traffic and the existing subgrade conditions. However, they are expected to function with periodic maintenance and overlays if good drainage is provided and maintained.

Subsequent to clearing, grubbing, and removal of topsoil, subgrade soils beneath all pavements should be scarified, moisture conditioned, and compacted to a minimum depth of 10 inches. All materials should meet the CALTRANS Standard Specifications for Highway Construction.

Aggregate base materials should meet the gradation and quality requirement of Class II

Aggregate Base (¾ inch maximum) in Caltrans Standard Specifications, latest edition, Sections

25 through 29.

Pavement Construction Considerations

Preventative maintenance should be planned and provided for through an on-going pavement management program in order to enhance future pavement performance. Preventative maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment.

Preventative maintenance consists of both localized maintenance (e.g. crack sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements.

Materials and construction of pavements for the project should be in accordance with the requirements and specifications of the State of California Department of Transportation, or other approved local governing specifications.

Base course or pavement materials should not be placed when the surface is wet. Surface drainage should be provided away from the edge of paved areas to minimize lateral moisture transmission into the subgrade.

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GENERAL COMMENTS

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather.

The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client.

Reliance upon the services and any work product is limited to our client and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing.

Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

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ATTACHMENTS

Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2

EXPLORATION AND TESTING PROCEDURES

Field Exploration

Basin Boring Type of Boring Boring Depth (feet) Location

F

B-20-1 Hollow-Stem Auger Boring 71.5 Pedestrian Bridge

B-20-2 Hollow-Stem Auger Boring 26.5 Pedestrian Bridge

P-20-1 Percolation Test Boring 46.5 Dry Well

P-20-2 Percolation Test Boring 46.5 Dry Well

G

B-20-3 Hollow-Stem Auger Boring 26.5 Pedestrian Bridge

B-20-4 Hollow-Stem Auger Boring 71.5 Pedestrian Bridge

P-20-3 Percolation Test Boring 46.5 Dry Well

P-20-4 Percolation Test Boring 46.5 Dry Well

Boring Layout and Elevations: Boring layout was prepared by Terracon personnel. The borings were located in the field by using the proposed site plan, an aerial photograph of the site, and handheld GPS. The accuracy of boring locations should only be assumed to the level implied by the method used.

Subsurface Exploration Procedures: We advanced the borings with a truck-mounted drill rig using continuous hollow stem flight augers. Four samples were obtained in the upper 10 feet in the hollow stem auger borings and two samples in the upper 10 feet in the percolation test borings.

Samples were obtained at intervals of 5 feet thereafter in all borings. Soil sampling was performed using split-barrel sampling procedures. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration

Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. A 2.5-inch O.D. split-barrel Modified California sampling spoon lined with rings was also used for sampling. The Modified California split-barrel sampling procedures are similar to standard split spoon sampling procedure; however, blow counts are typically recorded for 6-inch intervals for a total of 18 inches of penetration. The samples were placed in appropriate containers, taken to our soil laboratory for testing, and classified by a geotechnical engineer. In addition, we observed and recorded groundwater levels during drilling and sampling. For safety purposes, all borings were backfilled with auger cuttings after their completion.

The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory

Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2 for testing and classification by a Geotechnical Engineer. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the

Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

Laboratory Testing

The project engineer reviewed the field data and assigned laboratory tests to understand the engineering properties of the various soil strata, as necessary, for this project. Procedural standards noted below are for reference to methodology in general. In some cases, variations to methods were applied because of local practice or professional judgment. Standards noted below include reference to other, related standards. Such references are not necessarily applicable to describe the specific test performed.

■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture)

Content of Soil and Rock by Mass

■ ASTM D7263 Standard Test Methods for Laboratory Determination of Dry Density (Unit

Weight) of Soil Specimens

■ ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of

Soils

■ ASTM D1140 Standard Test Methods for Determining the Amount of Material Finer than

75-µm (No. 200) Sieve in Soils by Washing

■ ASTM D4546 Standard Test Methods for One-Dimensional Consolidation Properties of

Soils Using Incremental Loading

■ ASTM D3080 Standard Test Method for Direct Shear Test of Soils Under Consolidated

Drained Conditions.

■ Corrosivity Testing will include pH, chlorides, sulfates, sulfides, Redox potential, and electrical lab resistivity

The laboratory testing program included examination of soil samples by an engineer. Based on the material’s texture and plasticity, we described and classified the soil samples in accordance with the Unified Soil Classification System.

SITE LOCATION AND EXPLORATION PLANS

SITE LOCATION

Visalia Basin F and Amenities, and Basin G ■ Visalia, CA

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT

INTENDED FOR CONSTRUCTION PURPOSES

TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY

QUADRANGLES INCLUDE: VISALIA, CA (1/1/1969) and EXETER, CA (1/1/1969).

SITE

EXPLORATION PLAN

Visalia Basin F and Amenities, and Basin G ■ Visalia, CA

AERIAL PHOTOGRAPHY PROVIDED BY

MICROSOFT BING MAPS

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT

INTENDED FOR CONSTRUCTION PURPOSES

P-20-1: APPROXIMATE BORING AND

PERCOLATION TEST LOCATION

B-20-1: APPROXIMATE BORING LOCATION

Legend

E Mineral King Ave

5th A

ve. E.

A

A'

B

B' vvnguyen Line vvnguyen Line

EXPLORA…