Geotechnical Engineering Report_654-212.pdf

REPORT COVER PAGE

Geotechnical Engineering Report

Ionnis Lougaris Medical Center Boiler Plant No. 654-877 Reno, Nevada October 12, 2022

Terracon Project No. NB195089

Prepared for:

Spur Design, LLC.

Prepared by:

Terracon Consultants, Inc.

Sacramento, CA

Terracon Consultants, Inc. 50 Golden Land Court, Ste 100 Sacramento, CA 95834

P (916) 928-4690 F (916) 928 4697 terracon.com

REPORT COVER LETTER TO SIGN

October 12, 2022

Spur Design, LLC.

312 SW 25th Street 73109

Attn: Mr. Ryan Gibson P: (602) 584-5010 E: ryan.gibson@spur-design.com

Re: Geotechnical Engineering Report Ionnis Lougaris Medical Center Boiler Plant No. 654-877 975 Kirman Avenue Reno, Nevada Terracon Project No. NB195089

Dear Mr. Gibson:

We have completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Spur Design, LLC’s (Spur Design) MOD P00008 Change Order No. 1791.06-Spur-877 dated May 17, 2022. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations, floor slabs 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.

Beau D. Donaldson, P.E. Noah T. Smith, P.E., G.E. (CA) Associate Principal

12/31/22

Donaldso n, Beau D

Digitally signed by Donaldson, Beau D Date: 2022.10.12 12:03:01 -05'00' https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAA0LbF3VMueVUafVT6D0C7L32ObPQn3mAa

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

SEISMIC CONSIDERATIONS

LIQUEFACTION

CORROSIVITY

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

GENERAL COMMENTS

FIGURES

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

SUPPORTING INFORMATION

Note: Refer to each individual Attachment for a listing of contents.

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INTRODUCTION

Geotechnical Engineering Report Ionnis Lougaris Medical Center Boiler Plant No. 654-877

975 Kirman Avenue Reno, Nevada

October 12, 2022

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Ionnis Lougaris Medical Center (ILMC) boiler plant structure and paved parking area to be located at 975 Kirman Avenue and at the northwest corner of East Taylor Street and Kirman Avenue, respectively, in Reno, Nevada (ILMC Project No. 654-877).

The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

Subsurface soil conditions Floor slab design and construction

Groundwater conditions Seismic site classification per 2018 IBC

Site preparation and earthwork Lateral earth pressures

Demolition considerations Pavement design and construction

Excavation considerations Frost considerations

Foundation design and construction

This report also serves to supplement Terracon’s Geotechnical Engineering Report prepared for the Ionnis Lougaris Medical Center Seismic Project No. 654-212 (Terracon Project No.

NB195089) dated July 27, 2020.

The geotechnical engineering Scope of Services for this project included the advancement of 2 test borings (B-10 & B-11) within the proposed boiler plant footprint and 2 test borings (B-12 & B-

13) within the proposed parking lot footprint.

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.

Ionnis Lougaris Medical Center Boiler Plant No. 654-877 Reno, Nevada October 12, 2022 Terracon Project No. NB195089

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Item Description

Parcel Information

The proposed 8,500 (approximate) boiler plant structure is to be located at the southeast corner of Belli Drive and Kirman Avenue at 975 Kirman Ave in Reno, Nevada (Assessor Parcel No. 013-182-32)

The proposed 21,000 square foot (approximate) parking lot is to be located at the northwest corner of East Taylor Street and Kirman Avenue in Reno, Nevada (Assessor Parcel Nos. 013-124-12, 013-124-13 and 013-124-14).

Latitude and Longitude (approximate):

o Boiler Plant: 39.5164° N, 119.7981° W o Parking Lot: 39.5176° N, 119.7988° W

See Site Location

Existing Improvements

The sites are currently developed with the following:

Boiler Plant (southeast corner of Belli Drive and Kirman Avenue) o Asphalt paved parking lot. The proposed building’s footprint is bordered by Kirman Avenue to the west, Belli Drive to the north, a parking garage to the east and an existing boiler plant structure to the south.

Parking Lot (northwest corner of East Taylor Street and Kirman Avenue) o Gravel surfaced parking lot. The proposed parking lot footprint is bordered by East Taylor Street to the south, Kirman Avenue to the east, a residential alley to the north and residential homes to the west.

Current Ground Cover

Asphalt concrete pavement covers the proposed boiler plant footprint and gravel surfacing covers the proposed parking lot footprint.

Existing Topography (from Google Earth)

Both sites are relatively flat with gentle slopes on the order of less than 2 percent towards existing drainage inlets.

Geology

A Nevada Bureau of Mines and Geology geologic map indicates the native underlying soils at the site consist of middle to late Pleistocene Age (about 781,000 years ago to 12,000 years ago) Fluvial and Alluvial Deposits.1 The deposits are considered to consist of sands and gravels ranging in size from granules to boulders. The subsurface materials encountered in our explorations are generally consistent with the mapped geology.

1 Preliminary revised geologic maps of the Reno urban area, Nevada; Ramelli, A.R., Henry, C.D., Walker, J.P.; Nevada Bureau of Mines and Geology; 2011; 1:24,000

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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

Information Provided

Email sent by Mr. Ryan Gibson of Spur Design on May 3, 2022 which included a Statement of Work document prepared by the VA Sierra Nevada Health Care System.

Email sent by Mr. Gibson on June 17, 2022 which included a site plan showing the proposed footprint of the Boiler Plant.

Project Description The project will consist of the construction of a new Boiler Plant for the existing Ioannis Lougaris Veterans’ Administration Medical Center in Reno, NV. The project will also include paving the existing gravel surfaced parking located at the northwest corner of East Taylor Street and Kirman Avenue.

Proposed Structure

The tall (approximately 50 feet) boiler plant building will have a footprint of approximately 8,500 square feet. The building will have a main floor with a 2nd level mezzanine. A below grade chiller pit and steam pit will also be constructed within the structure. Each pit will have a footprint of approximately 200 square feet.

Building Construction The boiler plant structure will be blast protected and will be framed with steel, reinforced concrete and masonry concrete. The structure will have a concrete slab-on-grade.

Finished Floor Elevation Not provided; boring depths and our recommendations assumed that finished floor is not more than 2 feet below/above existing grades.

Maximum Loads

Anticipated structural loads were not provided. In the absence of information provided by the design team, we used the following loads in estimating settlement based on our experience with similar projects.

Columns: 150 to 200 kips Continuous: 4 to 8 kips per linear foot (klf) Slabs: 200 pounds per square foot (psf)

Grading A preliminary grading plan was not available for review at the time this report was prepared. We have assumed grading for the main building pad will be within ±2 feet of existing grades. Excavations on the order of 10 to 12 feet will be required to construct the proposed chiller pit and steam pit.

Below-Grade Structures The proposed chiller and steam pits floors will extend 10 feet below finished grades.

Retaining Walls None anticipated.

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Item Description

Pavements

Both rigid (concrete) and flexible (asphalt) pavement sections are being considered for the proposed 21,000 square foot parking lot located at the northwest corner of East Taylor Street and Kirman Avenue.

Anticipated Traffic Indices (TIs) are as follows:

Automobile Parking Area: Traffic Index of 4.5 Automobile Driving Lanes: Traffic Index of 5.5 Truck Parking: Traffic Index of 6.5

Anticipated Average Daily Truck Traffic values are as follows:

Car Parking and Access Lanes: ADTT = 1 (Category A) Truck Parking: ADTT = 25 (Category B) Dumpster Pads: ADTT = 100 (Category C)

The pavement design period is 20 years.

GEOTECHNICAL CHARACTERIZATION

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encountered at each exploration point are indicated on the individual logs. The individual logs can be found in the Exploration Results section and the GeoModel can be found in the Figures section of this report.

As part of our analyses, we identified the following model layers within the subsurface profile. For a more detailed view of the model layer depths at each boring location, refer to the GeoModel.

Model Layer Layer Name General Description 1 Surface Asphalt – approximately 3 to 4½ inches in thickness

2 Undocumented Fill

Fine to coarse grained, subrounded to subangular clayey sand with gravel. Gravel and cobble up to 4 inches in dimension.

3 Fat Clay Highly plastic, very stiff fat clay with fine grained sand.

4 Gravel Fine to coarse grained, subrounded to subangular clayey gravel with varying sand and clay content. Gravel and cobble up to 3 inches in dimension.

5 Sand Fine to coarse grained, subangular clayey sand with varying gravel and clay content. Gravels up to 1.5 inches in dimension.

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.

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Lab Results

Laboratory tests were conducted on selected soil samples and the test results are shown in the Exploration Results section and on the boring logs. An Atterberg limit test result with a plasticity index (PI) of 40 indicates the native fat clay soil encountered in test boring B-10 at a depth of approximately 5 feet bgs is highly plastic. An expansion index test performed on a bulk sample obtained from 1 to 4 feet bgs from boring B-11 indicates the near surface fill consisting of clayey sand with gravel in the area of boring B-11 is relatively non-expansive.

Groundwater Conditions

The boreholes were observed while drilling and after completion for the presence and level of groundwater. Groundwater was encountered in boring B-10 during drilling operations at a depth of approximately 41 feet bgs. Upon completing drilling operations for boring B-10, a second groundwater measurement was recorded at 40 feet bgs.

Groundwater data obtained from the State of Nevada’s Division of Water Resources NV Hydrology Data2 indicates the depth groundwater was as high as 15 feet bgs at a site located approximately 800 feet west of the site. The measurement was taken at point approximately 8 feet higher in elevation than the proposed parking lot site and approximately 20 feet higher in elevation than the proposed boiler plant site (approximate elevations obtained from Google Earth Pro). The measurement was taken July 27, 2007 (State Well Log No. 103673).

Based upon our explorations performed at this site in June 2020 and June 2022, we anticipate that groundwater at the site lies approximately 40 feet bgs. However, 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 anticipated. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Soil Classification is required to determine the Seismic Design Category for a structure. The Site Soil Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7-16.

2http://webgis.water.nv.gov/

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In order to better determine the boiler plant site’s Seismic Soil Classification, we analyzed data obtained from our test borings B-10 and B-11 in conjunction with the seismic information presented in Terracon’s Geotechnical Engineering Report (Terracon Report No. NB195089) dated July 27, 2020. Based on our analyses we have determined the site as Seismic Soil Class C.

The seismic design parameter for Risk Category IV are summarized in the following table:

Faulting and Estimated Ground Motions

The site is located in Northwest Nevada, 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. The site is located within proximity to three mapped, Latest Quaternary (<15,000 years), well constrained fault lines within the Mount Rose Fault Zone3. The fault lines are located approximately 300 feet north, 1,000 feet southwest, and 1,500 feet south of the project site. The fault ID is 1647 and falls into a Fault Class A.

Based on the OSHPD Seismic Design Maps Report, using the American Society of Civil Engineers (ASCE 7-16) standard, the peak ground acceleration (PGAM) at the project site is

3 https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=5a6038b3a1684561a9b0aadf88412fcf

Description Value

2018 International Building Code Site Soil Classification1 C2 Site Latitude 39.5164°N

Site Longitude 119.7981°W

Ss MCE3, 4 Spectral Acceleration for a Short Period 1.652 g

S1 MCE3, 4 Spectral Acceleration for a 1-Second Period 0.585 g

SDS Spectral Acceleration for a Short Period4 1.322 g

SD1 Spectral Acceleration for a 1-Second Period4 0.552 g

1. Seismic site soil classification in general accordance with the 2018 International Building Code, which refers to ASCE 7-16.

2. The 2018 International Building Code (IBC) uses a site profile extending to a depth of 100 feet for seismic site soil classification. The maximum geophysical survey depth performed for Terracon’s geotechnical engineering report (Terracon Report No. NB195089) dated July 27, 2020 is 100 feet. The geophysical survey measured the shear wave velocity profile as the site which was the basis for the Site Class determination.

3. MCE refers to Maximum Considered Earthquake.

4. These values were obtained using ASCE 7 Hazard Tool website (https://asce7hazardtool.online/).

Responsive Resourceful Reliable 7 expected to be 0.854g. Based on the USGS Unified Hazard Tool, the project site has a mean earthquake magnitude of 6.73.

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. Due to the presence of sands below groundwater level found in our field exploration, we have performed a liquefaction analysis at the site.

The liquefaction analysis for the site was 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 from boring B-10 and assuming existing fills encountered at the site will be removed and replaced as engineered fill in accordance with the Earthwork section shown later in this report. A Peak Ground Acceleration (PGA) of 0.854g and the mean magnitude of 6.73 for the project site were used. Calculations utilized a high groundwater depth of 15 feet bgs. Settlement analysis used the Tokimatsu, M-correction method and the fines percentage were corrected for liquefaction using the Stark/Olson method. The finished floor elevation of the proposed building is anticipated to be with ±2 feet of the existing grades at the site. In order to determine the seismically-induced settlement below the building, the liquefaction potential analysis was performed from the existing ground surface to 50 feet bgs. A factor of safety of 1.3 was used against liquefaction. See Exploration Results for detailed liquefaction analysis results.

Based on calculation results, seismically induced total settlement of saturated and unsaturated sands in the area of Boring B-10 is on the order of less than ¼-inches which is considered to be negligible. As such, the potential for liquefaction-induced lateral spreading should also be considered negligible.

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.

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Corrosivity Test Results Summary

Boring Sample Depth (feet)

Soil Description Soluble Sulfate

Soluble Chloride

Electrical Resistivity

( -cm) pH

B-11 1 to 4 Fill – Clayey Sand with Gravel <0.01 0.04 516 8.0

These test results are provided to assist in determining the type and degree of corrosion protection that may be required for the project. We recommend that a certified corrosion engineer determine the need for corrosion protection and design appropriate protective measures.

Resistivity

The resistivity value indicates the sample tested exhibits very high corrosive potential to metal.

Evaluation of the test results is based upon the guidelines of J.F. Palmer, “Soil Resistivity Measurements and Analysis”, Materials Performance, Volume 13, January 1974. The following table outlines the guidelines for soil resistivity for corrosion potential.

Corrosion Potential of Soil on Steel Soil Resistivity (ohm-cm) Corrosion Potential

0 to 1,000 Very High

1,000 to 2,000 High

2,000 to 5,000 Moderate

> 5,000 Mild

Sulfates The sulfate test result indicates that the soil from boring B-11 classifies as Class “S0” according to Table 19.3.1.1 of ACI 318-14. This indicates that the sulfate severity is negligible when considering corrosion to concrete. ACI 318-14, Section 19.3 does not provided restrictions to the type of concrete used for Sulfate Class “S0”. For further information, see ACI 318-14, Section 19.3.

Laboratory pH

Data suggests the soil pH should not be the dominant soil variable affecting soil corrosion if the soil has a pH in the 5 to 8 range. The pH of the sample tested is within the recommended range and therefore should not need to be considered when determining soil corrosion potential.

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GEOTECHNICAL OVERVIEW

Our explorations indicate that both the boiler plant and parking lot sites have fill soils extending from the existing ground surface to depths of 3½ to 4 feet bgs. The fill soils consisted of clayey sand with gravel and cobble. Gravel up to 3 inches in dimension and cobble up to 4 inches in dimension were present within the fill. The thickness of fill across the site may vary, and the thicknesses of fill encountered in our borings should not be construed as a minimum or maximum.

Additional fill may be present in areas where borings were not performed.

At this time, Terracon has not received documentation verifying fill was placed in a controlled manner. As such, we have considered the fill to be undocumented. Such undocumented fill can result in excessive erratic and differential settlements causing damage to proposed structures supported on shallow foundations, hardscapes, and pavements relying on the fill for structural support. Subsequently, the pre-existing surficial uncontrolled fills across the site are not suitable for the support of the improvements, which would be subject to unacceptable amounts of settlement. As a result, all undocumented fill within proposed areas of development should be over-excavated, moisture conditioned and recompacted to the specifications outlined in Earthwork. Debris or deleterious material (organic material, wood, plastic, glass, and/or construction debris), if encountered within the fill, should be screened and hauled off site.

If the owner elects to construct pavement and exterior hardscape on the existing undocumented fill as an alternative to the complete overexcavation of the undocumented fills, the following protocol should be followed. The fill below pavements and exterior slab areas should be over-excavated to a depth of 2 feet and the resulting subgrade should be scarified to a minimum depth of 12 inches, moisture conditioned, and compacted per the recommendations in Compaction Requirements. Following compaction of the subgrade, the over-excavated areas may be backfilled with compacted structural fill. The existing fill may be reused, provided the material is cleaned of any debris or deleterious material. A representative from Terracon should be present to observe the over-excavation of all fill. Once the planned subgrade elevation has been reached, the entire pavement area should be proofrolled. Areas of soft or otherwise unsuitable material should be undercut and replaced with either new structural fill or suitable, existing on-site materials.

Even with the recommended construction procedures, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the undocumented fill will not be discovered. To take advantage of the costs benefit of not removing the entire amount of undocumented fill, the owner must be willing to accept the inherent risk associated with pavement placed over the undocumented fill. The Pavements section addresses the design of pavement systems supported on undocumented fill soils.

The proposed boiler plant building may be supported by a shallow foundation system bearing on structural fill extending to a minimum depth of 2 feet below the bottom of foundations, or the depth

Responsive Resourceful Reliable 10 of undocumented fill, whichever is greater. Grading for the proposed building should incorporate the limits of the building plus a lateral distance of 5 feet beyond the outside edge of perimeter footings. The Shallow Foundations section addresses the design of foundations on structural fill.

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

We anticipate grading may consist of cuts and fills on the order of two feet or less and that site grades will remain at the same elevation as existing. Specific site grading information was unavailable at the time this report was prepared. If elevation and site grading differ from our stated assumptions, Terracon should be contacted to determine if additional earthwork recommendations are warranted, particularly with regard to potential ground settlement.

The following recommendations include demolition, 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, slabs, and pavements are contingent upon following the recommendations outlined in this section.

Site Preparation

Strip and remove existing vegetation, pavements, debris, and other deleterious materials from proposed building and pavement areas. Stripping should extend laterally a minimum of 5 feet beyond the limits of proposed improvements.

Though not encountered during our field exploration, it has been brought to our attention that an underground concrete utility tunnel exists within the footprint of the proposed boiler plant. We recommend that this tunnel or any other underground facilities such as septic tanks, cesspools and basements encountered during construction be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. If underground facilities are to remain in place, Terracon should be notified to ensure that the underground facilities will not increase the potential for differential settlements beneath the new boiler plant structure. We also recommend a structural engineer be notified so that they may inspect the existing underground facilities in order to ensure that the underground structures can support any new loads introduced from the proposed structure.

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Subgrade Preparation

After clearing, all undocumented fill within the proposed areas of development should be over-excavated, moisture conditioned and recompacted to the standards outlined below in Compaction Requirements. Although no debris was encountered in the fill during our exploration, any debris or deleterious material (organic material, wood, plastic, glass, and/or construction debris) found within fills should be screened and hauled off site.

As an alternative to the complete overexcavation of undocumented fill in pavement and exterior hardscape areas, the fill below pavements and exterior hardscape should be over-excavated to a minimum depth of 2 feet. The presence of over-sized debris or a high volume of organic material may warrant additional over-excavation at the time of grading operations. If needed, a geotextile fabric may be utilized as a separator between the undocumented fill and structural fill. However, even with the recommended construction procedures, there is an inherent risk for the owner that compressible fill or unsuitable material within or buried by the undocumented fill will not be discovered. To take advantage of the cost benefit of not removing the entire amount of undocumented fill, the owner must be willing to accept the inherent risk associated with pavement and exterior hardscape placed over the undocumented fill.

Excavated material may be stockpiled for use as fill provided it is cleaned of organic material, debris, and any other deleterious material and meets the criteria for general or structural fill specified in the Fill Material Types section of this report.

Once any required cuts and overexcavations are complete, all exposed areas which will receive fill, once properly cleared, should be scarified to a minimum depth of 12 inches, moisture conditioned as necessary, and compacted per the compaction requirements in this report. A representative from Terracon should be present to observe the exposed subgrade and verify the depth of scarification and moisture conditioning required.

Following scarification, moisture conditioning, and compaction of the subgrade, any required fill may be placed and compacted in accordance with the Fill Materials and Placement and Compaction Requirements sections of this report. The moisture content and compaction of subgrade soils should be maintained until foundation/slab/pavement construction. Care should be taken to prevent wetting or drying of the bearing materials during 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.

If drying is not an option, Terracon shall be contacted to provide additional stabilization recommendations.

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Excavation

Based on our test borings advanced near the site, deep excavations required for the proposed chiller and steam pits may encounter cobbles and or boulders. Excavations penetrating these cobbles/boulders may require the use of specialized heavy-duty equipment/jack-hammering 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.

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

Excavations as deep as 12 feet bgs may be performed for the proposed chiller and steam pits.

Groundwater is not anticipated to be encountered in excavations to this depth on the site.

The sidewalls of the pit excavations should be shored or sloped in conformance with local and OSHA excavation and trench safety standards. If any excavation is extended to a depth of more than 20 feet, it will be necessary to have the side slopes designed by a professional engineer.

Contractors are responsible for designing and constructing stable, temporary excavations.

Soils from the excavation should not be stockpiled higher than 6 feet or within 10 feet of the edge of an open trench. Construction of open cuts adjacent to existing structures, including underground pipes, is not recommended within a 1H:1V plane extending beyond and down from the perimeter of the structure. Cuts that are proposed within 5 feet of light standards, other utilities, underground structures, and pavement should be provided with temporary shoring.

It may be necessary for the contractor to retain a geotechnical engineer to monitor the soils exposed in all excavations and provide engineering services for slopes. This will provide an opportunity to monitor the soils encountered and to modify the excavation slopes as necessary.

It also offers an opportunity to verify the stability of the excavation slopes during construction.

Fill Materials and Placement

All fill materials should be inorganic soils free of vegetation, debris, and fragments larger than 3 inches in size. Pea gravel or other similar non-cementitious, poorly-graded materials should not be used as fill or backfill without the prior approval of the geotechnical engineer.

Clean on-site undocumented fill consisting of clayey sands with gravel may be used as engineered fill material provided it is screened to remove deleterious material. Fat clay soils encountered below the undocumented fill should not be used as engineered fill material and should be removed off-site. Screened on-site undocumented fill soils or approved imported materials may be used as fill material for the following:

general site grading foundation backfill foundation areas pavement areas

Responsive Resourceful Reliable 13 interior floor 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:

Gradation Percent Finer (by weight)* 3” 100 No. 4 Sieve 50 - 100 No. 200 Sieve 15 - 50

Property Property Liquid Limit 30 (max) Plasticity Index 10 (max) Expansive Index** 20 (max)

*ASTM C 136, ** ASTM D 4829

The contractor shall notify the Geotechnical Engineer of import sources at least two weeks prior to grading so 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 an exposure class “S0” for sulfate based upon current ACI criteria. 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.

Compaction Requirements

Compacted native soil and structural and general fill should meet the following compaction requirements.

Material Type and Location

Per the Modified Proctor Test (ASTM D1557) Minimum

Compaction Requirement

Range of Moisture Contents for Compaction Above Optimum

Minimum Maximum

Screened on-site undocumented fill soils or low-volume change imported fill:

Beneath foundations: 95 -2% +2% Beneath interior slabs: 95 -2% +2%

Fill greater than 5 feet in depth 95 -2% +2%

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Miscellaneous backfill and behind retaining walls: 90 -2% +2% Beneath pavements: 95 -2% +2%

Utility Trenches*: 90 -2% +2%

Bottom of excavation receiving fill: 90 0% +3% Aggregate base (beneath pavements): 95 -2% +2%

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

Utility Trenches

It is anticipated that the on-site soils 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 structural fill or 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 or public works department. Trench excavation should not be conducted below a downward 1:1 projection from existing foundations without engineering review of shoring requirements and geotechnical observation during construction.

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, deleterious substances, and cobbles larger than 3 inches in dimension.

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 slabs or 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.

All trench excavations should be made with sufficient working space to permit construction including backfill placement and compaction. If utility trenches are backfilled with relatively clean granular material, they should be capped with at least 18 inches of cementitious flowable fill or cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water through the trench backfill. Attempts should also be made to limit the amount of fines migration into the clean granular material. Fines migration into clean granular fill may result in unanticipated localized settlements over a period of time. To help limit the amount of fines migration, Terracon recommends the use of a geotextile fabric that is designed to prevent fines migration in areas of contact between clean granular material and fine-grained soils. Terracon also recommends that clean granular fill be tracked or tamped in place where possible in order to limit the amount of future densification which may cause localized settlements over time.

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Grading and Drainage

Positive drainage away from the improvements should be provided during construction and maintained throughout the life of the development. Water retained next to the building can result in soil movements greater than those discussed in this report. Greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto splash blocks or pavements at a distance of at least 10 feet from the building or are tied to tight lines that discharge into a storm drain system.

Infiltration of water into utility trenches or foundation excavations should be prevented during construction. 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.

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. If a minimum 5 percent slope cannot be achieved due to site grades, a minimum 2½ percent slope could be used provided pavement or hardscape surrounds and extends to the building, or a subdrain could be installed around the perimeter of the foundations that carries water away from the building. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building construction and landscaping have been completed, final grades should be verified to document effective drainage has been achieved.

Grades around the structure should also be periodically inspected and adjusted, as necessary, as part of the structure’s maintenance program.

Any planters and bio-swales located within 10 feet of the building should be self-contained or lined with an impermeable membrane to prevent water from accessing subgrade soils below the building. Sprinkler systems and landscaped irrigation should not be installed within 5 feet of foundation lines.

No vegetation over six feet in height shall be planted within 20 feet of the building perimeter unless a root barrier is provided between the structure and tree to limit roots within 10 feet of building.

Roots can draw additional moisture from the soils and cause excessive volume changes in the soil resulting in building movement.

Implementation of adequate drainage for this project can affect the surrounding developments.

Consequently, in addition to designing and constructing drainage for this project, the effects of site drainage should be taken into consideration for the planned structures on this property, the undeveloped portions of this property, and surrounding sites. Extra care should be taken to ensure irrigation and drainage from adjacent areas do not drain onto the project site or saturate the construction area.

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Earthwork Construction Considerations

Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of floor slabs 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. Water collecting over or adjacent to construction areas should be removed. 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 floor slab and pavement construction.

On-site clay 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 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.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, and/or state regulations. The Contractor is responsible for maintaining the stability of adjacent structures during construction.

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.

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Excavations or other activities resulting in ground disturbance have the potential to affect adjoining properties and structures. Our scope of services does not include review of available final grading information or consider potential temporary grading performed by the contractor for potential effects such as ground movement beyond the project limits. A preconstruction/ precondition survey should be conducted to document nearby property/infrastructure prior to any site development activity. Excavation or ground disturbance activities adjacent or near property lines should be monitored or instrumented for potential ground movements that could negatively affect adjoining property and/or structures.

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 the overexcavation of fill, 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 building areas and 4,000 square feet in pavement areas. Each lift of fill should be tested for density and water content at a frequency of at least one 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.

SHALLOW FOUNDATIONS

The proposed boiler plant building may be supported by spread footings bearing on engineered fill extending to a minimum depth of 2 feet below the bottom of foundations, or the depth of undocumented fill, whichever is greater. Grading for the proposed building should incorporate the limits of the building plus a lateral distance of 5 feet beyond the outside edge of perimeter footings.

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

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Design Parameters – Compressive Loads

Item Description Maximum Net Allowable Bearing pressure 1, 2 3,000 psf

Required Bearing Stratum 3 Engineered fill extending to a minimum depth of 2 feet below the bottom of foundations, or the depth of undocumented fill, whichever is greater.

Minimum Foundation Dimensions Columns: 30 inches Continuous: 18 inches

Maximum Foundation Dimensions Columns: 10 feet Continuous: 5 feet

Passive Resistance 4 (equivalent fluid pressures)

350 pcf

Coefficient of Sliding Friction 5 0.35

Minimum Embedment below

Finished Grade 6 24 inches

Estimated Total Settlement from Structural Loads 2 About 1 inch

Estimated Differential Settlement 2, 7 About ½ of total settlement

1. The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. A factor of safety has been applied. These bearing pressures can be increased by 1/3 for transient loads unless those loads have been factored to account for transient conditions. Values assume that exterior grades are relatively flat around the structure.

2. Values provided are for maximum loads noted in Project Description.

3. Unsuitable or soft soils should be over-excavated and replaced per the recommendations presented in the

Earthwork.

4. Use of passive earth pressures require the sides of the excavation for the spread footing foundation to be nearly vertical and the concrete placed neat against these vertical faces or that the footing forms be removed and compacted structural fill be placed against the vertical footing face. If passive resistance is used to resist lateral loads, the base friction should be reduced by 25 percent.

5. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Should be neglected for foundations subject to net uplift conditions.

6. Embedment necessary to minimize the effects of seasonal water content variations and frost. Finished grade is defined as the lowest adjacent grade within five feet of the foundation for perimeter (exterior) footings.

7. Differential settlements are as measured over a span of 40 feet.

8. Passive resistance and sliding friction may be combined to resist sliding provided the passive resistance is reduced by 50 percent.

Foundations should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement.

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Foundation Construction Considerations

As noted in Earthwork, the footing excavations should be evaluated under the observation of the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

If unsuitable bearing soils are observed at the base of the planned footing excavation, the excavation should be extended deeper to suitable soils, and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. The lean concrete replacement zone is illustrated on the following sketch.

To ensure foundations have adequate support, special care should be taken when footings are located adjacent to trenches. The bottom of such footings should be at least 1 foot below an imaginary plane with an inclination of 1.5 horizontal to 1.0 vertical extending upward from the nearest edge of the adjacent trench.

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FLOOR SLABS

Design parameters for floor slabs assume the building pad has been prepared in accordance with the Shallow Foundations and Earthwork sections above. Specific attention should be given to positive drainage away from the structure and positive drainage of the aggregate base beneath the floor slab.

Floor Slab Design Parameters

Item Description Interior floor system Slab-on-grade concrete Floor Slab Support Compacted engineered fill over firm native soil…