LANC Combined Specifications 4 of 4 Rev 001 6.20.24.pdf

REPORT COVER PAGE

Geotechnical Engineering Report

LA National Cemetery – Maintenance Complex Improvements

Los Angeles, CA

August 17, 2022

Terracon Project No. 60225045

Prepared for:

Vali Cooper International LLC

Denver, Colorado

Prepared by:

Terracon Consultants, Inc.

Carson, California

Terracon Consultants, Inc. 145. West Walnut St. Carson, Cali forn ia 90248

P [310] 627 3430 F [949] 261 6110 terracon.com

REPORT COVER LETTER TO SIGN

Vali Cooper International LLC

18300 E. 71st Avenue

Denver, Colorado 80249

Attn: Mr. Sean Fitzpatrick

P: (504) 684-4408 Ext 7540

E: sean@valiint.com

Re: Geotechnical Engineering Report

LA National Cemetery – Maintenance Complex Improvements

950 South Sepulveda Boulevard

Los Angeles, CA

Terracon Project No. 60225045

Dear Mr. Fitzpatrick:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Terracon Proposal No. P60215156 dated June

14, 2021, revised on June 28, 2021 (Vali Cooper Contract No. 2021-TCI-P-01 dated October 7, 2021) and Terracon Proposal No. P60225045 dated April 4, 2022 (Vali Cooper Modified Contract

2021-TCI-P-01_Mod-01 dated August 11, 2022).

This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations and pavements 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. Keith P. Askew, P.E., G.E.

Senior Staff Engineer Geotechnical Department Manager

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

SEISMIC CONSIDERATIONS

LIQUEFACTION ANALYSIS

CORROSIVITY

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

GENERAL COMMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS (Boring Logs and Laboratory Data)

SUPPORTING INFORMATION (Liquefaction Analysis, Seismic Design Parameters

Output, Unified Hazard Tool Output 2,475-Yr Return Period, Unified Hazard Tool Output

475-Yr Return Period, General Notes, and Unified Soil Classification System) http://client.terracon.com/

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INTRODUC TION

Geotechnical Engineering Report

LA National Cemetery – Maintenance Complex Improvements

950 South Sepulveda Boulevard

Los Angeles, CA

Terracon Project No. 60225045

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the Maintenance Complex Improvements Project proposed within the existing LA National Cemetery (LANC) at 950 South Sepulveda Boulevard, Los Angeles, CA. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Foundation design and construction

■ Groundwater conditions ■ Pavement design and construction

■ Site preparation and earthwork ■ Seismic site classification per CBC

■ Floor slab design and construction

The geotechnical engineering Scope of Services for this project included the advancement of five test borings to depths of 21½ to 51½ feet below existing site grades (bgs) and three pavement cores on October 29 and November 2, 2021. An additional two borings were advanced to an approximate depth of 21½ feet bgs on July 19, 2022 to obtain information for the proposed Bay

Maintenance Building expansion. Our scope of services also included providing a shear wave velocity survey, laboratory testing on samples retrieved from the borings, and preparation of this report.

Maps showing the site and boring locations 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.

LA National Cemetery – Maintenance Complex Improvements ■ Los Angeles, CA

August 17, 2022 ■ Terracon Project No. 60225045

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Item Description

Parcel Information

The project is situated within the LA National Cemetery located at 950 South

Sepulveda Boulevard in Los Angeles, CA.

Approximate coordinates for the center of the site are 34.0638°N, 118.4563°W

See Site Location

Existing

Improvements

The site resides within the existing Maintenance Complex. Existing improvements at the complex consist of minor parking and drive areas, existing buildings, retaining walls, and chain-link fencing.

Current Ground

Cover

Asphalt concrete and concrete surface at the Maintenance Complex. Asphalt concrete surface at San Juan Hill Avenue.

Existing Topography

(Google Earth)

Based on review of the site topographic survey, the Maintenance Complex surface is relatively flat and has an approximate elevation ranging from 379 to

383 feet. An ascending slope is located along the northeast boundary of the project site with a height of approximately 40 to 45 feet and an approximate inclination of 1.5H:1V (Horizontal to Vertical).

PROJECT DESCRIPTION

Our initial understanding of the project was provided in our proposal and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Existing Information

Based on review of the Construct Slope Protection Plans provided by the client, the ascending slope is located along the northeast boundary of the project site has an inclination of approximately 1.5H:1V (Horizontal to Vertical) and a vertical height of about 40 to 45 feet.

Furthermore, we understand that the slope was previously excavated, benched, and replaced with geogrid reinforced engineered fill with back and chimney drains. Additionally, we also understand that the bottom of the slope was keyed a minimum of 2 feet into firm natural ground.

Based on our understanding of the construction of the existing slope and our discussion with client, construction into or modification of the slope will not occur to avoid creating adverse slope stability conditions.

Proposed Structures

The project will include site improvements consisting of the following:

■ Approximately 1,300 square-foot rear building expansion to the existing Bay Maintenance Building.

■ Renovation of the existing historic brick storage building. The renovations will not require new footings or slabs.

■ Addition of privacy walls along perimeter of site.

Finished Floor

Elevation Assumed to be within one foot of existing grade.

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Item Description

Maximum Loads

(assumed)

■ Columns: 30-60 kips

■ Walls: 1 to 2 kips per linear foot (klf)

■ Slabs: 150 pounds per square foot (psf)

Grading Minimal cut/fill – assumed to be on the order of one foot, excluding any remedial grading requirements. Grading plans have not yet been provided.

Pavements New pavements will likely be constructed. We assume both rigid (concrete) and flexible (asphalt) pavement sections should be considered.

Traffic Loading

(assumed)

Anticipated traffic is as follows:

■ Parking Areas: Traffic Index of 4.5

■ Driving Lanes: Traffic Index of 5.5

Traffic loading should be verified by the civil engineer based on the anticipated traffic loading. Terracon should be notified if higher traffic loading is required.

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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 geotechnical characterization forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. As noted in General Comments, the characterization is based upon widely spaced exploration points across the site, and variations are likely.

Surface conditions encountered within our borings generally consisted of asphalt concrete and concrete within the Maintenance Complex and asphalt concrete along San Juan Hill Avenue.

Approximate thicknesses of pavement sections have been summarized in the table below.

Core ID Location Pavement Section Thicknesses (in)

(in) 1 MC-1

Maintenance Yard

7½ AC1

MC-2 3½ AC1

MC-3 2½ AC1

M-1 4 PCC

M-2 4¾ PCC over 9 AB

M-3 5 PCC over 6 AB

M-4 6 PCC over 6 AB

M-5 San Juan Hill Avenue 5 AC over 16 AB

AC – Asphalt Concrete; AB – Aggregate Base; PCC – Portland Cement Concrete

1. Aggregate base layer, if present, was not advanced and measured at these locations.

Subsurface conditions encountered within the borings, beneath the pavement, generally consisted of loose to dense sand with varying amounts of silt, clay, and gravel with interbedded layers of stiff to hard silty clay and clay with varying amounts of sand and gravel to a maximum explored depth of 51½ feet bgs. Plasticity Index testing performed on samples retrieved resulted in 5 to 20. A very dense layer of silty sand was encountered in boring M-2 at an approximate depth of 50 feet bgs. Traces of cobbles were encountered near the surface in the soil borings.

Due to the existing development, undocumented fill soils are likely present on the site; the depth and lateral extent of undocumented fill soils were not easily discernable during our field investigation, and therefore not identified on the boring logs.

Boring M-5 was drilled along San Juan Hill Avenue which is located atop the slope adjacent to the maintenance complex to obtain subsurface information for the evaluation of the slope situated along the northeastern boundary of the maintenance complex. As such, subsurface conditions encountered in boring M-5 may not be indicative of the conditions surrounding the maintenance buildings. Additionally, a shear wave velocity study was performed along the top of the slope to obtain information regarding excavation characteristics of the slope/embankment. The design of

Responsive ■ Resourceful ■ Reliable 5 the project subsequently changed, and evaluation of the slope is no longer part of our scope. The shear wave velocity study was performed by Atlas Technical Consultants, LLC and included performing one-dimensional Refraction Microtremor (ReMi) and Multichannel Analysis of Surface

Wave (MASW) profiles; this data is provided as an attachment to this report. As this survey was performed at the top of the existing slope, the data is likely not indicative of the subsurface conditions where improvements are now proposed.

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 on samples retrieved indicate a low to medium plasticity. Consolidation testing conducted on samples from borings M-4 and M-6 at an approximate depth of 2½ feet bgs resulted in a collapse potential of less 1 percent when saturated under normal footing loads of 2,000 psf. A direct shear test conducted on a sample retrieved from boring M-5 at an approximate depth of 10 feet bgs resulted in an ultimate effective friction angle of 32 degrees and cohesion of 100 pounds per square foot

(psf).

Groundwater Conditions

Groundwater was observed in boring M-2 at an approximate depth of 48 feet bgs.

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.

Based on review of Plate 1.2 of the Seismic Hazard Zone Report (SHZP) for the Beverly Hills 7.5-

Minute Quadrangle, historic groundwater elevation within the vicinity of the site is estimated to be at approximately 30 feet bgs.

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.

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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 11.4.8 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) 34.0638

Site Longitude (°W) 118.4563

Ss Spectral Acceleration for a 0.2-Second Period 2.01 g

S1 Spectral Acceleration for a 1-Second Period 0.72 g

Fa Site Coefficient for a 0.2-Second Period 1.0

Fv Site Coefficient for a 1-Second Period 1.7

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 51½ feet, and this seismic site class definition considers that similar 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.

Typically, a site-specific ground motion study will generate less conservative coefficients and acceleration values which may reduce 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.

Faulting and Estimated Ground Motions

The site is located in Southern 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 Santa Monica Fault, which is considered to have the most significant effect at the site from a design standpoint, is located 1.9 kilometers from the site and has a maximum credible earthquake magnitude of 7.11 based on a return period of 2,475 years and 6.95 based on a return period of 475 years.

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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 0.942 g. Based on the USGS Unified Hazard Tool, the project site has a mean magnitude of 6.86 based on a return period of 2,475 years (2% in 50-year return period) and 6.7 based on a return period of 475 years (10% in 50-year return period). Furthermore, the site is not located within an Alquist-Priolo Earthquake Fault Zone based on our review of the State Fault

Hazard Maps.1

LIQUEFACTION ANALYSIS

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. Based on a review of California Geologic Survey Zones of Required Investigation Map for the Beverly Hills

Quadrangle, the site is mapped as being within or just bordering an identified liquefaction zone;

therefore, we performed a liquefaction analysis.

Liquefaction analysis for the site was performed in general accordance with the DMG Special

Publication 117 and City of Los Angeles criteria. The liquefaction study utilized the software

“LiquefyPro” by CivilTech Software, and was based on the subsurface conditions from boring M-

2 and a historic groundwater elevation of 30 feet bgs. Based on the City of Los Angeles liquefaction analytical criteria, Site Modified Peak Ground Acceleration (PGAM) of 0.94 g and mean moment magnitude of 6.86 were used for a return period of 2,475 years (2% in 50-year return period). For 475-year return period (10% in 50-year return period), a PGA of 0.63 g (two-third of PGAM) and mean moment magnitude of 6.7 were used. Based on City of Los Angeles criteria, liquefaction analysis was performed using the factor of safety of 1.0 for the 2,475-year return period and factor of safety of 1.1 for the 475-year return period. Settlement analysis used the Tokimatsu, M-correction method. Fines were corrected for liquefaction using modified Modify

Stark/Olson method.

Based on the data obtained in boring M-2, laboratory test results, and the criteria outlined above, total and differential seismically-induced settlement is anticipated to be less than ¼ of an inch for the return period of 475 years. For 2,475-year return period, the total seismically-induced settlement is anticipated to be approximately 1 inch and differential settlement is anticipated to be approximately ½ inch.

1 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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CORROSIVITY

The results of laboratory sulfides, soluble sulfate, soluble chloride, electrical resistivity, redox potential, total salts, and pH testing are presented in our appendix within the Exploration Results section. 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.

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.

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.

Geotechnical engineering recommendations for foundation systems and other earth connected phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, and our current understanding of the proposed project.

The near-surface soils encountered were generally soft sandy clay or loose clayey sand. These soils will require removal and recompaction during construction. Additionally, undocumented fill soils are likely present on the site that were not easily identified; however, we anticipate these soils will be relatively shallow. Recommendations regarding the depth and limits of remedial grading are provided herein are designed to minimize the impacts of loose, soft, and undocumented fill soils within the proposed building pads. Based on Plasticity Index testing, the expansion characteristics of the on-site soils do not require any special treatment and may be used as backfill.

A retaining wall was previously proposed with a configuration that excavated within the ascending slope located along northeast boundary of the project site; however, based on the Construct Slope

Protection Plans provided by the client, the existing slope was reconstructed with layers of geogrid. It is our opinion that excavation into the existing slope could create adverse slope stability conditions. We understand that this wall is no longer proposed.

Based on the conditions encountered, the proposed buildings can be supported on shallow foundations provided the grading recommendations provided herein are implemented.

file:///C:/Users/vvnguyen/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/H58U2EMT/ffb%2060215168%20Renovations%20at%20The%20Pierpont%20Inn%20GeoReport%20(002).docx%23ExplorationResults

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Due to the presence of low bearing capacity soils near the surface and anticipated total and differential settlements, foundations and floor slabs should bear on engineered fill extending to a minimum depth of 3 feet below the bottom of foundations, or 5 feet below existing grades, whichever is greater. Grading for the proposed foundations should incorporate the limits of the footings plus a lateral distance of 3 feet beyond the outside edge of perimeter footings, where space is available.

Based on the findings summarized in this report, it is our professional opinion that the proposed construction will not be subjected to a hazard from settlement, slippage, or landslide, provided the recommendations of our report are incorporated into the proposed construction. It is also our opinion that the proposed construction will not adversely affect the geologic stability of the site or adjacent properties provided the recommendations contained in our report are incorporated into the proposed construction.

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

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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.

Support of pavements on or above existing fill materials is discussed in this report. However, even with the recommended construction testing services, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the fill will not be discovered. This risk of unforeseen conditions cannot be eliminated without completely removing the existing fill, but can be reduced by performing additional testing and evaluation.

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, pavements, and other deleterious materials from proposed building 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.

Although no evidence of fills, utilities, or underground facilities such as septic tanks, cesspools, basements, and utilities was observed during the site reconnaissance, such features could be encountered during construction. If unexpected fills, utilities, 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 presence of low bearing capacity soils near the surface and anticipated total and differential settlements, foundations and floor slabs should bear on engineered fill extending to a minimum depth of 3 feet below the bottom of foundations, or 5 feet below existing grades, whichever is greater. Grading for the proposed foundations should incorporate the limits of the footings plus a lateral distance of 3 feet beyond the outside edge of perimeter footings, where space is available.

Localized deeper removals may be needed where loose or soft soils are encountered at the excavation bottom. In the event the demolition activities result in disturbance of deeper soils, the subgrade preparation and compaction should extend to the depth of undisturbed soils.

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Subgrade soils beneath exterior slabs and pavements should be removed to a depth of 1 foot below the bottom of proposed slab or pavement section (including aggregate base materials), or the existing grade (exposed subgrade after demolition of pavement), whichever is greater.

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. The moisture content and compaction of subgrade soils should be maintained until exterior slab or pavement construction.

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

We anticipate that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. The bottom of excavations should be thoroughly cleaned of loose soils and disturbed materials prior to backfill placement and/or construction.

We anticipate that cobbles may be encountered during excavation. Excavation penetrating the cobbles layer may require the use of specialized heavy-duty equipment, together with drilling to facilitate rock break-up and removal. Consideration should be given to obtaining a unit price for difficult excavation in the contract documents for the project.

As new foundations are constructed adjacent to the existing foundations, there is a risk that the bearing material could become undermined and/or overstressed due to overlapping stresses. Provisions should be made during construction to prevent undermining or disturbing the soils supporting the existing foundations. Excavations should not extend below an imaginary 1H:1V inclined plane projecting below the bottom edge of any adjacent existing foundations as shown in the figure to the right.

Maintaining a sufficient clear distance between new and existing foundations will reduce the potential for increased bearing stresses and additional foundation settlement. Connections between the existing building and the new addition should allow for some differential movement.

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.

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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.

Clean 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 exterior slab areas interior slab 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.

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.

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Compaction Requirements

Recommended compaction and moisture content criteria for 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 and interior slabs: 90 0% +3%

Beneath pavements: 95 0% +3%

Fill greater than 5 feet in depth: 90 0% +3%

Miscellaneous backfill: 90 0% +3%

Utility Trenches : 90 0% +3%

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

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

1. Upper 12 inches should be compacted to 95% within 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. Planters and other surface features which could retain water in areas adjacent to the building or wall foundations or pavements should be sealed or eliminated.

In areas where sidewalks or paving do not immediately adjoin the structure, 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 and sprinkler line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration.

Roof drainage should discharge into splash blocks or extensions when the ground surface beneath such features is not protected by exterior slabs or paving. Sprinkler systems and landscaped irrigation should not be installed within 5 feet of foundation walls.

Exterior Slab Design and Construction

Where subgrade soils are sandy, exterior slabs-on-grade, exterior architectural features, and utilities founded on, or in backfill may experience some movement due to the volume change of the backfill.

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To reduce the potential for damage caused by movement, we recommend:

minimizing moisture increases in the backfill;

controlling moisture-density during placement of backfill;

using designs which allow vertical movement between the exterior features and adjoining structural elements;

placing effective control joints on relatively close centers.

Compacted subgrade composed of on-site clay dominant soils will expand with increasing moisture content; therefore, exterior concrete slabs may heave, resulting in cracking or vertical offsets. The potential for damage would be greatest where exterior slabs are constructed adjacent to the building or other structural elements. To reduce the potential for damage caused by movement, we recommend:

exterior slabs should be supported directly on subgrade fill (not ABC) with no, or very low expansion potential;

strict moisture-density control during placement of subgrade fills;

maintain proper subgrade moisture until placement of slabs;

placement of effective control joints on relatively close centers and isolation joints between slabs and other structural elements;

provision for adequate drainage in areas adjoining the slabs;

use of designs which allow vertical movement between the exterior slabs and adjoining structural elements.

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.

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.

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Construction Considerations

Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of exterior slab and 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 exterior slab and pavement construction.

On-site clayey soils may pump, and unstable subgrade conditions could develop during general construction operations, particularly if the soils are wetted and/or subjected to repetitive construction traffic. The use of light construction equipment would aid in reducing subgrade disturbance. The use of remotely operated equipment, such as a backhoe, would be beneficial to perform cuts and reduce subgrade disturbance.

Should unstable subgrade conditions develop stabilization measures will need to be employed.

Stabilization measures may include placement of aggregate base and multi-axial geogrid. Use of lime, fly ash, kiln dust or cement could also be considered as a stabilization technique. Laboratory evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction.

We recommend that the earthwork portion of this project be completed during extended periods of dry weather if possible. If earthwork is completed during the wet season (typically November through April) it may be necessary to take extra precautionary measures to protect subgrade soils.

Wet season earthwork operations may require additional mitigative measures beyond that which would be expected during the drier summer and fall months. This could include diversion of surface runoff around exposed soils and draining of ponded water on the site. Once subgrades are established, it may be necessary to protect the exposed subgrade soils from construction traffic.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

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.

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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 building 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. This testing frequency criteria may be adjusted during construction as specified by the geotechnical engineer of record.

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.

sean Rectangle

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SHALLOW FOUNDATIONS

Provided the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Shallow Foundation Design Recommendations

DESCRIPTION RECOMMENDATION

Structures Building expansion and privacy walls

Foundation Type Spread footing foundations

Subgrade Preparation Requirements

Engineered fill should extend to a minimum depth of 3 feet below the bottom of foundations, or 5 feet below existing grades, whichever is greater.

Allowable Bearing pressure (based on settlement)

2,500 psf

Minimum Dimensions Spread: 24 inches

Continuous: 18 inches

Minimum Embedment Depth Below Finished

Grade 18 inches

Total Estimated Settlement (Static and Seismic ) 1½ inch

Estimated Differential Settlement Less than ¾ inch over 40 feet

1. Based on return period of 475 years

Settlement calculations were performed utilizing Westergaard and Hough's methods2 to estimate the static settlement for various foundation widths with an allowable settlement of 1-inch.

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.

2 FHWA Geotechnical Engineering Circular No. 6 – Shallow Foundations, FHWA-SA-02-054.

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FLOOR SLABS

DESCRIPTION RECOMMENDATION

Interior floor system Slab-on-grade concrete

Floor slab support Engineered fill extending 3 feet below the bottom of footings or 5 feet below existing grades, whichever is greater.

Subbase Minimum 4-inches of Aggregate Base

Modulus of subgrade reaction

150 pounds per square inch per inch (psi/in) (The modulus was obtained based on estimates obtained from NAVFAC 7.1 design charts). This value is for a small loaded area (1 Sq. ft or less) such as for forklift wheel loads or point loads and should be adjusted for larger loaded areas.

The use of a vapor retarder should be considered beneath concrete slabs on grade covered with wood, tile, carpet, or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

Saw-cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should be sealed with a water-proof, non-extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments.

Where floor slabs are tied to perimeter walls or turn-down slabs to meet structural or other construction objectives, our experience indicates differential movement between the walls and slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the length of the structural dowels. The Structural Engineer should account for potential differential settlement through use of sufficient control joints, appropriate reinforcing or other means.

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LATERAL EARTH PRESSURES

Design Parameters

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

ITEM VALUEa, b

Active Case 40 psf/ft

Passive Case 375 psf/ft

At-Rest Case 60 psf/ft

Surcharge Pressure 0.31 x Surcharge load (psf)

Coefficient of Friction 0.30 aNote: The values are based on engineered fill materials 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 125 pcf.

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 R-value of 10 was used to calculate the asphalt concrete pavement thickness sections and the Portland cement concrete pavement sections. R-value testing should be performed on subgrade soils once design grades are achieved and 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.

Pavement Section Thicknesses

The following table provides options for AC and PCC Sections for various Traffic Indices (TI).

Traffic loading should be verified by the owner or civil engineer based on anticipated vehicular count during the operation of the proposed facility.

Recommended Pavement Section Thickness

Light (Automobile) Parking

Assumed Traffic Index (TI) = 4.5

On-site Driveways Assumed

TI = 5.5

Section I

Portland Cement Concrete* 5.0-inches PCC over 4-inches

Class II Aggregate Base 6.0-inches PCC over 4-inches

Class II Aggregate Base

Section II

Asphalt Concrete

3-inches AC over 8-inches Class II Aggregate Base

4-inches AC over 9-inches Class II Aggregate Base

AB: Class 2 Aggregate Base; PCC: Portland Cement Concrete; AC: Asphalt Concrete

* Unreinforced plain jointed

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 12 inches. All

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It is our experience that asphalt pavement sections will suffer severe distresses and shoving in tight turning radiuses areas. It is our recommendations that Portland cement concrete pavement should be used for such areas.

All concrete for rigid pavements should have a minimum flexural strength of 600 psi (4,250 psi

Compressive Strength) and be placed with a maximum slump of four inches. Proper joint spacing will also be required to prevent excessive slab curling and shrinkage cracking. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer.

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.

Pavement Construction Considerations

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…