IFB_250103_Geotech_Reports.PDF

Geotechnical Evaluation

Jacobs Park Improvements Tucson, Arizona

Norris Design

418 North Toole Avenue | Tucson, Arizona 85701

May 18, 2023 | Project No. 607560001

Geotechnical | Environmental | Construction Inspection & Testing | Forensic Engineering & Expert Witness

Geophysics | Engineering Geology | Laboratory Testing | Industrial Hygiene | Occupational Safety | Air Quality | GIS

1991 East Ajo Way, Suite 145 | Tucson, Arizona 85713 | p. 520.577.7600 | www.ninyoandmoore.com

Geotechnical Evaluation

Jacobs Park Improvements

Tucson, Arizona

Mr. Jason Kuklinski

Norris Design

418 North Toole Avenue | Tucson, Arizona 85701

May 18, 2023 | Project No. 607560001

MJK/SDN/FFN/jom

Marek J. Kasztalski, PE Principal Engineer

Fred F. Narcaroti Principal/Tucson Office Manager http://www.ninyoandmoore.com/

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 i

CONTENTS

1 INTRODUCTION 1

2 SCOPE OF SERVICES 1

3 SITE DESCRIPTION 1

4 TOPOGRAPHIC MAP AND AERIAL PHOTOGRAPH REVIEW 2

5 PROPOSED CONSTRUCTION 2

6 FIELD EXPLORATION AND LABORATORY TESTING 3

7 GEOLOGY AND SUBSURFACE CONDITIONS 4

7.1 Subsurface Conditions 5

7.1.1 Fill 5

7.1.2 Alluvium 5

7.2 Groundwater 5

8 GEOLOGIC HAZARDS 5

8.1 Land Subsidence and Earth Fissures 6

8.2 Faulting and Seismicity 6

9 CONCLUSIONS 7

10 RECOMMENDATIONS 7

10.1 Earthwork 7

10.1.1 Site Preparation 8

10.1.2 Excavations 8

10.1.3 Fill Materials and Reuse of On-site Soils 8

10.1.4 Subgrade Preparation 9

10.1.5 Fill Placement and Compaction 10

10.1.6 Pipe Bedding 10

10.1.7 Trench Backfill 11

10.2 Seismic Design Considerations 11

10.3 Foundations 12

10.3.1 Shallow Foundations 12

10.3.2 Drilled Concrete Piers 13

10.3.3 Post-Tensioned Slabs 14

10.4 Slab-On-Grade 15

10.5 Flatwork 15

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10.6 Pavements 16

10.6.1 Traffic 16

10.6.2 Subgrade 16

10.6.3 New Pavement Sections 17

10.7 Corrosion 17

10.8 Concrete 18

10.9 Site Drainage 18

10.10 Construction Observation and Testing 18

11 LIMITATIONS 19

12 REFERENCES 21

TABLES

1 – NRCS Soil Units 4

2 – Compaction Recommendations 10

3 – International Building Code Seismic Design Criteria 11

4 – Design Parameters for Lateral Pile Capacity Analysis 13

5 – PTI Parameters – Pickleball Courts 14

6 – PTI Estimated Edge Moisture Variation Distance (em) – Pickleball Courts 14

7 – PTI Post Equilibrium Parameters – Pickleball Courts 15

8 – Subgrade Soil Correlated R-value Summary 16

9 – Recommend Structural Pavement Sections 17

FIGURES

1 – Site Location

2 – Exploration Locations

APPENDICES

A – Boring Logs

B – Laboratory Testing

B -1 – Agricultural Testing

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 1

1 INTRODUCTION

In accordance with our proposal dated January 12, 2023, and your authorization, we have performed a geotechnical evaluation for the design and construction of the proposed improvements at the Jacobs Park in Tucson, Arizona (Figure 1). The purpose of our evaluation was to assess the subsurface conditions at the project site in order to provide geotechnical recommendations for design and construction. This report presents the results of our evaluation and our geotechnical conclusions and recommendations regarding the proposed construction.

2 SCOPE OF SERVICES

The scope of our services for this project generally included:

• Reviewing available topographic information, soil surveys, geologic literature, and aerial photographs of the project areas.

• Conducting a visual reconnaissance of the project area and marking out the exploration locations.

• Notifying Arizona 811 of the proposed exploration locations prior to conducting our field work.

• Drilling, logging, and sampling 30 exploratory soil borings to approximate depths of 5 to 25 feet below ground surface (bgs). The boring logs are presented in Appendix A.

• Collecting nine near-surface bulk soil samples using hand-operated equipment for agricultural testing.

• Performing laboratory tests on selected samples collected from our borings to evaluate the in-situ moisture content and dry density, gradation, Atterberg limits, consolidation, corrosivity characteristics (including pH, minimum electrical resistivity, and soluble sulfate and chloride contents), and agricultural properties. The results of the laboratory tests are included in Appendix B and B-1.

• Preparing this report presenting our findings, conclusions, and recommendations regarding the proposed design and construction.

Our scope of services did not include environmental consulting services such as hazardous waste sampling or analytical testing at the site. A detailed scope of services and estimated fee for such services can be provided upon request.

3 SITE DESCRIPTION

The project site is located east and west of Fairview Ave between Prince Road to the north and

Miracle Mile to the south, in Tucson, Arizona (Figure 2). At the time of our evaluation, the site included active sports/recreational amenities; including seven turf/grass surfaced soccer fields, Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 2 one turf/grass surfaced baseball field, three basketball courts, two tennis courts a swimming pool, two asphalt concrete (AC) paved entrance drive, and a parking lot located along Fairview

Avenue that bisects the site in an east to west direction. Other existing site features included ramadas, a play structure, a single-story masonry building, Portland cement concrete

(PCC) walkways, and restrooms. The Santa Cruz River was located approximately 1 1/2 miles to the southwest of the site and the Rillito River was located approximately 1 3/4 miles to the north of the site.

4 TOPOGRAPHIC MAP AND AERIAL PHOTOGRAPH REVIEW

According to the Tucson North, Arizona, 7.5-Minute United States Geological Survey (USGS)

Topographic Quadrangle Map (2021), the average elevation of the site is approximately 2,320 feet relative to mean sea level (MSL). The topography of the project area slopes gently from southwest to northeast.

Several historical aerial photographs from Historicaerials.com (Nationwide Environmental Title

Research [NETR]) and from Google Earth™ were reviewed for this project. Aerial images dated

1958 depicted North Fairview Avenue and the project site as agricultural land with surrounding streets already in place and an adjacent residential neighborhood. Images dated 1967 depicted first sports facilities (swimming pool and tennis courts) in the southern portion of the site, while the northern portion was still mostly undeveloped. An image dated 1972 showed the first two baseball/softball fields within the park. Aerial photographs dated 1980 through 2018 depicted the project site west of Fairview Avenue as being similar to its current condition. Aerials images dated 1996 showed construction development on the east side of Fairview Avenue, beginning with AC paved parking lots, ramadas and a single soccer field. Images dated 2003 through 2019 depicted the project site as being similar to its current condition.

5 PROPOSED CONSTRUCTION

We understand that the City of Tucson plans to construct improvements at Jacobs Park in

Tucson, Arizona. The main improvements will include:

• Four softball fields, with new irrigation system, dugouts, bull pens, covered bleachers and new Musco field lighting system for each field (supported on drilled concrete piers);

• New lighted sand volleyball courts;

• New lighted skate park;

• Parking lot improvements;

• New lighted pickleball courts;

• New batting cages;

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• New splash pad;

• New restroom building (City of Tucson “Standard Restroom”);

• New group ramadas (pre-engineered structures); and

• Other miscellaneous improvements and associated utilities.

Engineering plans for the proposed improvements were not available at the time this report was prepared. However, we have assumed that the project construction will not involve any major grading operations and the project site grades will be within 2 feet of the currently existing grades. We further understand that any new at-grade structures will include slabs-on-grade and/or spread footings. Based on the data provided by the project design team, the Musco lighting poles will be supported on 30-inch diameter drilled concrete piers extending on the order of 8 to 14 feet below existing grade.

6 FIELD EXPLORATION AND LABORATORY TESTING

On April 18th through April 20th, 2023, Ninyo & Moore conducted a subsurface exploration in order to evaluate the subsurface conditions and to collect soil samples for laboratory testing.

Our evaluation consisted of drilling, logging, and sampling of 30 exploratory borings using a

CME 75 truck mounted drill rig equipped with hollow-stem augers (Figure 2). The borings, denoted as B-1 through B-20 (for various site improvements) and LP-1 through LP-10 (for the

Musco light poles), extended to approximate depths of 5 to 25 feet bgs. Bulk and relatively undisturbed soil samples were collected at selected depth intervals in our borings. We also collected nine near-surface bulk soil samples for agricultural testing, denoted as AS-1 through

AS-9, using hand-operated equipment.

Ninyo & Moore personnel logged the borings in general accordance with the Unified Soil

Classification System (USCS) and American Society for Testing and Materials (ASTM) test method D 2488 by observing cuttings and drive samples. Collected ring samples were trimmed in the field, wrapped in plastic bags, and placed in cylindrical plastic containers to retain in-place moisture conditions. Similarly, Standard Penetration Test (SPT) and bulk samples were sealed in plastic bags to retain their approximate in-place moisture. Detailed descriptions of the soils encountered are presented on the boring logs in Appendix A.

The soil samples collected from our exploratory activities were transported to the Ninyo & Moore laboratory in Tucson, Arizona for geotechnical laboratory testing. The testing included in-situ moisture content and dry density, gradation, Atterberg limits, consolidation, corrosivity characteristics (including pH, minimum electrical resistivity, and soluble sulfate and chloride contents), and agricultural properties. The results of the in-situ moisture content and dry density

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 4 testing are presented on the boring logs in Appendix A and a description of each laboratory test method and the remainder of the test results are presented in Appendices B and B-1.

7 GEOLOGY AND SUBSURFACE CONDITIONS

The project sites are located in the Sonoran Desert Section of the Basin and Range physiographic province, which is typified by broad alluvial valleys separated by steep, discontinuous, subparallel mountain ranges. The mountain ranges generally trend north-south and northwest-southeast. The basin floors consist of alluvium with thickness extending to several thousands of feet.

The basins and surrounding mountains were formed approximately 18 million years ago during the mid- to late-Tertiary age. Extensional tectonics resulted in the formation of horsts

(mountains) and grabens (basins) with vertical displacement along high-angle normal faults.

Intermittent volcanic activity also occurred during this time. The surrounding basins were filled with alluvium from the erosion of the surrounding mountains as well as from deposition from rivers. Coarser-grained alluvial material was deposited at the margins of the basins near the mountains.

The surface geology at the sites is described as Quaternary-age alluvial stream channels, low stream terraces, and relatively undissected alluvial fans. Soils formed in these deposits range from undeveloped to moderately developed. Calcium carbonate accumulations are quite variable, ranging from minimal to cemented pans, depending on the calcium carbonate content of the parent material and soil leaching conditions. (Pearthree, et al, 1998).

According to the United States Department of Agriculture (USDA), Natural Resource

Conservation Service (NRCS) online Web Soil Survey, various soil types are encountered within the project site. The predominant soil types are described in Table 1 below.

Table 1 – NRCS Soil Units

Soil Map Unit Name Description of Soil Units

Comoro sandy loam Sandy loam, Loamy fine sand

Mohave sand loam Sandy loam, clay loam, loam

Mohave loam Loam, clay loam

Notes:

Loam is an agricultural soil classification that refers to a soil comprised of a mixture of clay, silt, and sand.

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7.1 Subsurface Conditions

The boring logs contain our field and laboratory test results, as well as our interpretation of conditions believed to exist between actual samples retrieved. Therefore, these boring logs contains both factual and interpretive information. Lines delineating subsurface strata on the boring logs are intended to group soils having similar engineering properties and characteristics.

They should be considered approximate, as the actual transition between soil types (strata) may be gradual. Detailed stratigraphic information as well as a key to the soil symbols and terms used on the boring logs are provided in Appendix A.

7.1.1 Fill

Undocumented fill soil was encountered at the surface of boring B-15 and extended to an approximate depth of 3 feet bgs. The fill soil consisted of hard sandy lean clay with trace gravel.

7.1.2 Alluvium

Native alluvial soil deposits were observed at the surface of our borings or under the fill, and extended to the boring termination depths. The alluvium encountered in our borings consisted of loose to very dense deposits of clayey sand and silty sand with variable amounts of gravel, and firm to hard sandy lean clay. The relative density of the alluvial deposits generally increased with depth in our borings. Zones of carbonate cementation

(caliche) were encountered at many locations at variable depths.

7.2 Groundwater

Groundwater was not encountered in our exploratory borings. Based on well data provided by the Arizona Department of Water Resources (ADWR), groundwater has been historically measured at a depth on the order of 180 feet bgs in the project area. However, it should be noted that groundwater levels near the site can fluctuate due to seasonal variations, flows in nearby washes, irrigation, groundwater withdrawal or injection, and other factors.

8 GEOLOGIC HAZARDS

The following section provides a discussion regarding potential geologic hazards such as land subsidence, earth fissures, faulting and seismicity.

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8.1 Land Subsidence and Earth Fissures

Groundwater depletion, due to groundwater pumping, has caused land subsidence and earth fissures in numerous alluvial basins in Arizona. It has been estimated that subsidence has affected more than 3,000 square miles and has caused damage to a variety of engineered structures and agricultural land. From 1948 to 1983, excessive groundwater withdrawal has been documented in several alluvial valleys where groundwater levels have been reportedly lowered by up to about 500 feet. With such large depletions of groundwater, the alluvium has undergone consolidation resulting in large areas of land subsidence (Schumann and Genualdi, 1986).

In Arizona, earth fissures are generally associated with land subsidence and pose an on-going geologic hazard. Earth fissures generally form near the margins of geomorphic basins where significant amounts of groundwater depletion have occurred. Reportedly, earth fissures have also formed due to tensional stress caused by differential subsidence of the unconsolidated alluvial materials over buried bedrock ridges and irregular bedrock surfaces (Schumann and

Genualdi, 1986).

Based on our field reconnaissance and review of the referenced material, there are no known earth fissures at the surface of the subject site. Based on fissure maps published by the Arizona

Geological Survey (AZGS, 2014), the closest reported unconfirmed earth fissures to the site are located approximately 14 miles to the northwest of the project site near the Town of Marana

(Shipman, 2007).

Continued groundwater withdrawal in the area may result in subsidence and the formation of new fissures or the extension of existing fissures. While the future occurrence of land subsidence and earth fissures cannot accurately be predicted, these phenomena are not expected to be a constraint to the construction of this project.

8.2 Faulting and Seismicity

The project sites are situated within the Sonoran zone, which is a relatively stable tectonic region located in southwestern Arizona, southeastern California, southern Nevada, and northern

Mexico (Euge et al., 1992). This zone is characterized by sparse seismicity and few Quaternary faults. Based on our field observations and on our review of readily available published geologic maps and literature, there are no known active faults underlying the subject area or adjacent areas. The closest known Quaternary fault to the sites is the Santa Rita Fault Zone, located approximately 24 miles southeast of the project area. The Santa Rita Fault Zone is situated along the western piedmont of the Santa Rita Mountains. The fault zone is a series of northeast

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 7 striking normal faults that dip to the northwest. The most recent movement along this fault was approximately 130,000 years ago during the Middle to Late Pleistocene epoch. The slip-rate category of this fault is less than 0.2 millimeters per year (Pearthree, 1998). Seismic parameters recommended for the design of the proposed improvements are presented in Section 10.2.

9 CONCLUSIONS

Based on the results of our subsurface evaluation, laboratory testing, and data analysis, the proposed construction is feasible from a geotechnical standpoint, provided the recommendations of this report are incorporated into the design of the project, as appropriate.

Geotechnical considerations include the following:

• The surface site soils can generally be excavated or ripped using heavy-duty earthmoving or excavation equipment. However, zones of cementation and gravel should be anticipated, which may result in difficult and/or slower excavation rates.

• Soils of variable relative densities encountered near the ground surface in our borings may be compressible upon saturation.

• Imported soils and soils generated from on-site excavation activities, that exhibit a relatively low plasticity index (PI) can generally be used for engineered fill. Based on the results of our study, many of the on-site soils will not be suitable for re-use as engineered fill.

• Groundwater was not observed in our borings. Based on ADWR well data, the regional groundwater table has been historically measured at depths on the order of 180 feet bgs in the project area. In general, groundwater is not expected to be a constraint to the design and construction of this project.

• No documented geologic hazards are present underlying or immediately adjacent to the site.

• Corrosivity test results indicate that on-site soils are corrosive to ferrous materials and the sulfate content of the soils presents a negligible to moderate sulfate exposure to concrete.

10 RECOMMENDATIONS

The following sections present our geotechnical recommendations for the project design and construction. If the proposed construction is changed from that discussed in this report, Ninyo & Moore should be contacted for additional recommendations.

10.1 Earthwork

The following sections provide our earthwork recommendations for this project. In general, the earthwork specifications contained in the Pima Association of Governments (PAG) Standard

Specifications for Public Improvements (Standard Specifications) are expected to apply unless specifically noted.

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10.1.1 Site Preparation

Construction areas should be cleared of deleterious materials, if any are present, construction debris, vegetation, and any other material that might interfere with the performance or progress of the work. These materials should be disposed of at a legal dumpsite. Existing features that call for relocation or removal and extend below finish grade, if present, should be removed, and the resulting excavations backfilled with compacted engineered fill as discussed in this report.

10.1.2 Excavations

Our evaluation of the excavation characteristics of the on-site soils is based on the results of our exploratory boring, site observations, and experience with similar soils. The surface site soils can generally be excavated or ripped using heavy-duty earthmoving or excavation equipment. However, zones of caliche cementation and gravel are present on the site and may result in difficult and/or slower excavation rates.

Sidewalls for temporary excavations should not be anticipated to stand near-vertical without sloughing. Therefore, the contractor should provide safely sloped excavations or an adequately constructed and braced shoring system, in compliance with Occupational Safety and Health Administration (OSHA) regulations, for employees working in an excavation that may expose them to the danger of moving ground. For planning purposes and according to

OSHA soil classifications, a "Type C" soil should be considered for this project. This corresponds to a temporary slope inclination no steeper than 1.5:1 (horizontal to vertical

[H:V]). During excavation, soil classification and excavation performance should be evaluated in the field by Ninyo & Moore in accordance with the OSHA regulations.

10.1.3 Fill Materials and Reuse of On-site Soils

On-site and imported soils that exhibit relatively low plasticity indices and very low to low expansive potential are generally suitable for re-use as engineered fill. Relatively low plasticity indices are defined as a PI value of 15, or less, as evaluated by ASTM D4318.

Based on laboratory test results, the shallow-depth (upper 10 feet) on-site soils are characterized by PI values ranging from 0 (non-plastic) to 31. As such, it is our opinion that many of the on-site soils will not be suitable for re-use as engineered fill during construction. The Contractor should perform additional testing prior to or during construction to better delineate the soil conditions at the site.

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In addition, clay lumps, construction debris and rock particles should not be larger than 4 inches in dimension. Any unsuitable material should be disposed of off-site or in non-structural areas.

Engineered fill materials in contact with ferrous metals should also have low corrosion potential (minimum resistivity more than 2,000 ohm-cm, chloride content less than 25 parts per million [ppm]). Engineered fill material in contact with concrete should have a soluble sulfate content of less than 0.1 percent.

10.1.4 Subgrade Preparation

As stated previously, our borings disclosed near-surface fill and alluvial material generally consisting of loose to very dense silty and clayey sand. Based on our field and laboratory test results, the near-surface fill and alluvial material may exhibit collapse potential upon saturation. Accordingly, we recommend that new shallow foundations (spread footings) be supported on a zone of engineered fill that extends 2 feet below the bottom of the new foundation or 4 feet below current grade; whichever is deeper. The engineered fill placed within this overexcavated zone should be placed as discussed in Section 10.1.6. This overexcavation zone should extend a horizontal distance from the edge of the new foundation that is equal to the depth of the overexcavation.

In addition, we recommend that any slabs-on-grade, post tensioned slabs, flatwork and pavement be supported on 12 inches of moisture-conditioned and compacted engineered fill, as measured from the bottom of the aggregate base (AB) course or leveling layer, where applicable. This subgrade improvement should extend laterally 1 foot beyond the slab-on-grade, post tensioned slab, flatwork and pavement footprint.

As indicated in Section 10.6 Pavements, the recommended pavement sections assume a design R-value of 15 or higher. We recommend that the subgrade soils within 2 feet below the bottom of the AB layer satisfy the aforementioned design R-value. Areas, where the actual R-values do not meet this recommendation should be improved. Possible soil improvements may include soil overexcavation and replacement with suitable material, lime stabilization, or blending with other suitable materials.

After the overexcavation described above is finished and prior to the placement of engineered fill, exposed surfaces from excavations should be carefully evaluated by

Ninyo & Moore for the presence of soft, loose, or wet soils that were not removed as part of the improvement process. This evaluation should consist of probing and visual observation of the excavation bottom. Based on this evaluation, additional remediation may be needed.

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This could include further scarification of the exposed surface. This additional remediation, if needed, should be addressed by the geotechnical consultant during the earthwork operations.

10.1.5 Fill Placement and Compaction

Engineered fill soils should be moisture-conditioned within the moisture range shown below in Table 2 and mechanically compacted to the percent compaction shown. Engineered fill should generally be placed in 8-inch-thick loose lifts such that each lift is firm and non-yielding under the weight of construction equipment.

Table 2 – Compaction Recommendations

Engineered Fill Description

Percent Compaction per

ASTM D698

Moisture Content

Under spread footings, slab-on-grade, post tensioned slabs, pavements, and flatwork

95 percent ±2 percent of optimum

Aggregate Base (AB) 100 percent ±2 percent of optimum

Trench Backfill – within 2 feet below pavements

100 percent ±2 percent of optimum

Trench Backfill – deeper than 2 feet below pavement

95 percent ±2 percent of optimum

Pipe Bedding/Pipe Zone 95 percent ±2 percent of optimum

An earthwork (shrinkage) factor of 10 to 20 percent is estimated. This shrinkage factor range represents an average of the material tested and assumes that materials excavated from the site will be placed as fill. Potential bidders should consider this in preparing estimates and should review the available data to make their own conclusions regarding excavation conditions.

10.1.6 Pipe Bedding

We recommend that new pipelines be supported on 6 inches or more of graded granular bedding material meeting the Standard Specifications. This bedding/pipe-zone backfill should extend 1 foot above the pipe crown. Care should be taken not to allow voids to form beneath the pipe (i.e., the pipe haunches should be continuously supported) to avoid damaging the pipeline. This may involve fill placement by hand or small compaction equipment. When backfilling, care should be taken to fill voids with compacted material so that excessive settlement of the backfill will not occur.

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The bedding/pipe-zone should be placed in lifts of approximately 8 inches in loose thickness and compacted as detailed in Section 10.1.5 above.

10.1.7 Trench Backfill

Suitable backfill should not include organic material, construction debris, or other non-soil fill materials. Rock particles and clay lumps should not be larger than 4 inches in dimension.

Generated excavation materials that contain this oversize fraction shall not be used as backfill unless the oversize fraction has been processed or removed from the material.

Unsuitable material should be disposed of off-site or in non-structural areas. We anticipate that the on-site soils will generally be suitable for re-use as the trench backfill.

Trench backfill should be mechanically compacted to a relative compaction as detailed in

Section 10.1.5 above. Lift thickness for backfill will be dependent upon the type of compaction equipment utilized, but should generally be placed in lifts not exceeding

8 inches in loose thickness. Special care should be exercised to avoid damaging the pipe or other structures during the compaction of the backfill. In addition, the underside (or haunches) of the buried pipe should be supported on a well-graded, compacted bedding material. This area may need placement by hand or small-scale compaction equipment.

10.2 Seismic Design Considerations

Design of the proposed improvements should be performed in accordance with the requirements of the governing jurisdictions and applicable building codes. Table 3 presents the seismic design parameters for the site in accordance with International Building Code (IBC) guidelines and adjusted maximum considered earthquake spectral response acceleration parameters evaluated using the California’s Office of Statewide Health Planning and

Development Seismic Design Maps (web based).

Table 3 – International Building Code Seismic Design Criteria

Site Coefficients and Spectral Response Acceleration Parameters Values

Site Class D

Site Coefficient, Fa 1.584

Site Coefficient, Fv 2.40

Mapped Spectral Response Acceleration at 0.2-second Period, Ss 0.270 g

Mapped Spectral Response Acceleration at 1.0-second Period, S1 0.083 g

Spectral Response Acceleration at 0.2-second Period Adjusted for Site Class, SMS 0.428 g

Spectral Response Acceleration at 1.0-second Period Adjusted for Site Class, SM1 0.200 g

Design Spectral Response Acceleration at 0.2-second Period, SDS 0.285 g

Design Spectral Response Acceleration at 1.0-second Period, SD1 0.133 g

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 12

10.3 Foundations

Based upon our review of field exploration and laboratory test results, we are providing recommendations for shallow foundations, drilled concrete piers, and post-tensioned slabs. We understand that the foundation system used will be selected by others based on loading conditions, settlement tolerances of the structures, as well as associated costs and constructability.

10.3.1 Shallow Foundations

Spread footings should be supported at a depth of 18 inches or more below finished grade, bearing on engineered fill in accordance with recommendations presented in Sections

10.1.4 and 10.1.5. Continuous footings should have a width of 16 inches or more, and isolated column footings should have a width of 24 inches or more. Footings may be designed using the allowable net bearing pressure of 2,500 pounds per square foot (psf) for static conditions and the footing depth of 18 inches or more below finished grade.

The allowable soil bearing pressure may be increased by one-third when considering total loads including loads of short duration such as wind or seismic forces.

Total and differential settlement of 1-inch and 1/2-inch over a horizontal distance of 40 feet, respectively, may occur. These settlement estimates are based on the estimated loading conditions, the available soil boring information, and our experience with similar soils.

These settlements are contingent on the preparation of soils underlying the footings in accordance with the recommendations contained in Section 10.1.5 of this report.

Foundations bearing on engineered fill and subject to lateral loadings may be designed using an ultimate coefficient of friction of 0.35 (total frictional resistance equals the coefficient of friction multiplied by the dead load). An ultimate passive resistance value of

300 psf per foot of depth may be used up to a value of 3,000 psf. The ultimate lateral resistance can be taken as the sum of the frictional resistance and passive resistance, provided that the passive resistance does not exceed one-half of the total allowable resistance. The passive resistance may be increased by one-third when considering loads of short duration such as wind or seismic forces. The foundations should preferably be proportioned such that the resultant force from lateral loadings falls within its kern (i.e., middle one-third).

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10.3.2 Drilled Concrete Piers

We understand that the proposed Musco lighting poles will be supported on drilled concrete piers. An allowable end bearing capacity of 2,500 psf may be used for evaluating pier performance in compression. An allowable lateral bearing capacity of 250 psf per foot of depth may be used to design drilled piers to resist lateral loads. Lateral bearing capacity should be neglected in the upper 3 feet, below the ground surface. The allowable capacity values may be increased by one-third when considering loads of short duration such as wind or seismic loads. Drilled piers loaded to the allowable capacity may be designed for total and differential static settlements of about ½ inch

The parameters listed in Table 4 may be used to evaluate the resistance to lateral loads and corresponding peak moment for the drilled pier. Pier reinforcement should be designed by the structural engineer.

Table 4 – Design Parameters for Lateral Pile Capacity Analysis

Soil Layer Soil Layer

(ft)

Unit Weight

(pcf)

Friction Angle

(degree)

Cohesion (ksf) e50

K (pci)

Clay 3.0 – 12.0 110 - 2,000 0.005 500

Sand Below 12.0

115 32 - - 80

Notes: ft – feet; pcf – pounds per cubic foot; ksf – kips per square foot; pci – pounds per cubic inch

The pier should be drilled as closely as possible within specified limits of vertical and horizontal alignment. The pier should not be out of plumb by more than 5 percent over the length of the pier. Furthermore, the top of the pier should be within 3 inches of the design location. The pier should be drilled to the specified depth, and the pier bottom should be cleaned of loose material prior to pouring concrete. Standing water, if encountered, should be removed from the pier excavation or the concrete should be delivered to the bottom of the excavation, below the water surface, by tremie pipe. Concrete should be placed in the pier in a manner that reduces the potential for segregation of the components.

A representative of Ninyo & Moore should observe the drilling and construction of the pier to check that the embedment criteria are satisfied, the materials encountered match the design assumptions, and that the appropriate construction procedures are followed.

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10.3.3 Post-Tensioned Slabs

The Post Tensioning Institute (PTI) design parameters were estimated based on the stratigraphic information described in our boring logs, and using the procedures outlined in the Post-Tensioning Institute Manual Design of Post-Tensioned Slabs-on-Ground, 3rd edition with 2008 Supplement. It should be noted that these parameters may change depending on the type of engineered fill used beneath the structures. The parameters presented in this report assume our recommendations for engineered fill and subgrade preparation will be followed.

Differential vertical swell has been estimated for center lift and edge lift conditions for use in designing foundation slabs for the stratigraphy encountered in our borings. These values were calculated using a computer program titled VOLFLO Win 1.5 and the parameters presented in Table 5.

Table 5 – PTI Parameters – Pickleball Courts

Parameter Design Value

Allowable Net Bearing Capacity 1,500 psf

Approximate Thornthwaite Moisture Index -40

Constant Soil Suction 3.5 pF

Depth of Seasonal Moisture Variation approximately 15 feet

Percent Finer than 2 Microns 15

Soil Fabric Factor 1.0

Table 6 presents the Estimated Edge Moisture Variation Distance (em) due to shrinking soils

(center lift condition) and due to swelling soils for the pickleball courts. These values were calculated based on the guidelines provided in the PTI 3rd Edition Manual.

Table 6 – PTI Estimated Edge Moisture Variation Distance (em) – Pickleball Courts

Condition em, (ft) Change in Suction Design Envelope

Center Lift (Shrinking) 9 Wet to Constant

Edge Lift (Swelling) 4 ½ Dry to Constant

The PTI Manual recommends that the Post Equilibrium case be used in geographic areas with Thornthwaite indices (Im) wetter than +15 and dryer than -15. The Im value for the project site is approximately -40.

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The unrestrained differential soil movement (ym) is calculated based on the Post Equilibrium case guidelines provided in the PTI Manual, where pF varies from 3.0 to 4.5 are presented in Tables 7 below.

Table 7 – PTI Post Equilibrium Parameters – Pickleball Courts

Condition ym, (in) Change in Suction Design Envelope

Center Lift (Shrinking) - ½ Wet to Constant

Edge Lift (Swelling) 1 Dry to Constant

The estimated moisture variation distance around the differential soil movements presented above do not consider the effects of non-climatic factors (e.g., tree location, landscaping, etc. depth of exterior grade beams or other moisture retardant, etc.)

10.4 Slab-On-Grade

The design of the slab-on-grade is the responsibility of the structural engineer. Placement of the reinforcement in the slab is vital for satisfactory performance. The slabs should be underlain by

4 or more inches of aggregate base material in general accordance with the Standard

Specifications. We recommend that the slab-on-grade be supported on engineered fill as described in Section 10.1.4 of this report.

The slab-on-grade should either be constructed so that it “floats” independent of the foundations or be designed to be structurally connected to the foundations. Fill soils under slabs should be maintained in a moist condition until the overlying slab is constructed. Joints should be constructed at intervals designed by the structural engineer to help reduce random cracking of the slab.

10.5 Flatwork

To reduce the potential manifestation of distress to any concrete flatwork due to movement of the underlying soil, we recommend that such flatwork (if utilized for this project) be installed with crack-control joints at appropriate spacing as designed by the structural engineer. We recommend that concrete flatwork be supported on engineered fill as described in Section

10.1.4 of this report. Positive drainage should be established and maintained adjacent to flatwork. We also recommend that a flexible sealant be applied at the joints where flatwork abuts building foundations, as well as in control joints that exhibit post-construction cracking to reduce the introduction of moisture adjacent to the foundations. The flexible sealant should be installed and maintained in accordance with the manufacturer’s recommendations.

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10.6 Pavements

The new pavement sections were developed in accordance with the Pima County Roadway

Design Manual, 2013 Edition with June 2016 updates (Manual). The sections below present our main design assumptions and recommended new pavement sections. We assumed that the subgrade preparation recommendations outlined in this report will be employed. The service life for the new pavement sections presented below is estimated to be on the order of

20 years.

10.6.1 Traffic

Traffic information for this project was not available as of the date of this study. However, we anticipate that the driveways will be used mainly by passenger car traffic, and occasionally by delivery and maintenance trucks.

10.6.2 Subgrade

The subsurface soils encountered in our borings generally consisted of silty clayey sand with variable percentages of gravel. Table 8 summarizes the correlated R-values.

Table 8 – Subgrade Soil Correlated R-value Summary

Boring No. Sample Depth (feet) Pima County Correlated

R-value

B-9 0.0 – 5.0 23

B-12 0.0 – 5.0 21

B-14 0.0 – 5.0 9

B-17 0.0 – 5.0 7

The mean R-value calculated for this project is 15 and indicates that the existing subgrade soils may need improvement prior to pavement construction. We recommend that soils with a construction control R-value of 15 be used for this project subject to subgrade improvement as stipulated in Section 10.1.4. R-value of 15 was also used for the structural pavement design. For a seasonal variation factor of 1.7, a resilient modulus of 6,946 psi was estimated for the subgrade soils in conformance with the Manual. We recommend that the new pavements be supported on improved subgrade as described in Section 10.1.5 of this report.

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10.6.3 New Pavement Sections

The recommended AC structural pavement sections are presented in Table 9 below.

Table 9 – Recommend Structural Pavement Sections

Pavement Section

AB

(inches)

AC

(inches)

Driveways 6.0 3.5

Parking Areas 6.0 2.5

If PCC pavement is anticipated in the trash collection area, the concrete slab should be

6 inches thick and should be placed on 4 inches of AB.

10.7 Corrosion

The corrosion potential of the on-site materials was analyzed to evaluate its potential effect on the foundations and structures. Corrosion potential was evaluated using the results of laboratory testing of soil samples obtained during our subsurface evaluation that were considered representative of soils at the subject site.

Laboratory testing consisted of pH, minimum electrical resistivity, and chloride and soluble sulfate contents. The pH and minimum electrical resistivity tests were performed in general accordance with Arizona Test 236c, while sulfate and chloride tests were performed in accordance with Arizona Test 733 and 736, respectively. The results of the corrosivity tests are presented in Appendix B.

The soil pH value of the tested samples varied between 8.2 and 8.8, which is considered to be alkaline. The minimum electrical resistivity measured in the laboratory ranged between 720 and

1,140 ohm-cm, which is considered to be corrosive to ferrous metals. The chloride content of the samples tested varied between 53 and 330 parts per million (ppm), which is also considered to represent a corrosive environment to ferrous metals. The soluble sulfate content of the soil samples varied between 0.02 and 0.15 percent by weight, which is considered to represent negligible to moderate sulfate exposure for concrete.

The results of the laboratory testing indicate that the on-site materials are corrosive to ferrous materials. It is possible that soils with variable corrosivity characteristics may be encountered at the site and should be evaluated during construction. We recommend that topsoil, organic soils, soils, and mixtures of sand and clay not be placed adjacent to buried metallic utilities. We further suggest that sand or gravel be placed around buried metal piping. Also, buried utilities of different metallic construction or operating temperatures should be electrically isolated from

Ninyo & Moore | Jacobs Park Improvements, Tucson, Arizona | 607560001 | May 18, 2023 18 each other to minimize galvanic corrosion problems. In addition, new piping should be electrically isolated from old piping, if any, so that the old metal will not increase the corrosion rate of the new metal. A corrosion specialist should be consulted for further recommendations.

10.8 Concrete

Laboratory chemical tests performed on soil samples indicated sulfate content of approximately

0.02 and 0.15 percent by weight. Based on American Concrete Institute (ACI), the on-site soils should be considered to represent negligible to moderate sulfate exposure to concrete.

We recommend the use of Type II cement for construction of concrete structures at this site.

Due to potential uncertainties as to the use of reclaimed irrigation water, or topsoil that may contain higher sulfate contents, pozzolan or admixtures designed to increase sulfate resistance may be considered.

The concrete should have a water-cementitious materials ratio of no more than 0.50 by weight for normal weight aggregate concrete. The structural engineer should select the concrete design strength based on the project specific loading conditions. ACI recommends 4,000 pounds per square inch (psi) for a 20-day compressive strength. Higher strength concrete may be selected for increased durability and resistance to slab curling and shrinkage cracking.

We recommend that concrete cover over reinforcing steel for foundations be in accordance with the recommendations of the structural engineer. The structural engineer should be consulted for additional concrete specifications.

10.9 Site Drainage

Surface drainage should be provided to divert water away from and off of the new improvements. In addition, surface water should not be permitted to drain toward or to pond adjacent to the new improvements. Positive drainage for this project is defined as a slope of 2 or more percent for a distance of 5 or more feet away from the new improvement footprint.

10.10 Construction Observation and Testing

During construction operations, we recommend that Ninyo & Moore perform observation and testing services for the project. These services should be performed to evaluate exposed subgrade conditions, including the extent and depth of overexcavation, to evaluate the suitability of the on-site materials for use as fill, and to observe placement and test compaction of fill soils.

Qualified subcontractors utilizing appropriate techniques and construction materials should perform construction of the proposed improvements.

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11 LIMITATIONS

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

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

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

Our conclusions, recommendations, and opinions are based on an analysis of the observed site conditions. If geotechnical conditions different from those described in this report are encountered, our office should be notified and additional recommendations, if warranted, will be provided upon request. It should be understood that the conditions of a site could change with time as a result of natural processes or the activities of man at the subject site or nearby sites.

In addition, changes to the applicable laws, regulations, codes, and standards of practice may occur due to government action or the broadening of knowledge. The findings of this report may, therefore, be invalidated over time, in part or in whole, by changes over which Ninyo & Moore has no control.

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

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12 REFERENCES

American Concrete Institute, Guidelines for Concrete Floor and Slab Construction (ACI 302.1R).

American Concrete Institute, Guidelines for Residential Cast-in-Place Concrete Construction

(ACI 332R).

Arizona Department of Water Resources, Well Registry Application, https://gisweb.azwater.gov/waterresourcedata/.

Arizona Department of Water Resources (ADWR), 2000, Total Land Subsidence in the Tucson Metropolitan Area, 11/09/1993 to 09/20/2000;

Arizona Department of Water Resources (ADWR), 2010, Total Land Subsidence in the Tucson Metropolitan Area, 02/14/2003 to 01/08/2010;

Arizona Department of Water Resources (ADWR), 2019, Total Land Subsidence in the Tucson Metropolitan Area, 05/15/2010 to 04/16/2020;

American Society for Testing and Materials (ASTM), Annual Book of ASTM Standards.

Euge, K.M., Schell, B.A., and Lam, I.P., 1992, Development of Seismic Acceleration Contour Maps for Arizona: Arizona Department of Transportation Report No. AZ 92-344: dated September.

Google, Inc., Google Earth™ mapping service, http://earth.google.com.

International Code Council, 2015, International Building Code.

Nationwide Environmental Title Research (NETR), LLC, Historic Aerials by NETR Online, http://historicaerials.com/.

Ninyo & Moore, In-house proprietary information.

Occupational Safety and Health…