Attachment 2_Geotechnical Report.pdf

ECS Southwest, LLP Geotechnical Engineering Report

National Cemetery Development

Cedar City Rural Initiative

2181 W. 1600 S.

Cedar City, Utah

ECS Project Number 17:5539

April 22nd, 2021

April 22, 2021 Mr. Mark Dyck Gordon 148 S. Queen Street, Suite 201 Martinsburg, WV 25401

ECS Project No. 17:5539

Reference: Geotechnical Engineering Report

National Cemetery Development Cedar City Rural Initiative 2181 W. 1600 S.

Cedar City, Utah

Dear Mr. Dyck:

ECS Southwest, LLP (ECS) has completed the subsurface exploration, laboratory testing, and geotechnical engineering analyses for the above-referenced project. ECS Southwest, LLP (ECS) conducted this subsurface exploration and geotechnical engineering evaluation in accordance with ECS Proposal No. 17- 6783 dated December 15, 2020. This report presents our understanding of the geotechnical aspects of the project, the results of the field exploration and laboratory testing conducted, and our recommendations for design and construction.

It has been our pleasure to be of service during the design phase of this project. We would appreciate the opportunity to remain involved during the continuation of the design phase, and we would like to provide our services during construction phase operations as well to verify the subsurface conditions considered for this report. Should you have any questions concerning the information contained in this report, or if we can be of further assistance to you, please contact us.

Respectfully submitted, ECS Southwest, LLP

Connor F. Roman, P.E. Michael Sorgenfrei, P.E., P.G.

Department Manager Principal, Branch Manager croman@ecslimited.com msorgenfrei@ecslimited.com

Electronic seal approved by Michael Sorgenfrei, P.E. on April 22, 2021.

National Cemetery Development April 22, 2021 ECS Project No. 17:5539 Page 1

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION

1.1 General

1.2 Scope of Services

1.3 Authorization

2.0 PROJECT INFORMATION

2.1 Project Location

2.2 Current Site Conditions

2.3 Proposed Construction

3.0 FIELD EXPLORATION

3.1 Field Exploration Program

3.1.1 Test Borings

3.1.2 Test Pits

3.1.3 Penetration Tests and Sampling

3.1.4 Rock Coring

3.2 Regional Geology & Faulting

3.3 Subsurface Characterization

3.4 Groundwater Observations

4.0 GEOTECHNICAL LABORATORY TESTING

5.0 DESIGN RECOMMENDATIONS

5.1 Conventional Strip and Spread Footing Foundations

5.2 Non-Structural Slab-on-Grade Floors

5.3 Seismic Design Considerations

5.4 Retaining Walls

5.5 Pavement Design

5.5.1 Pavement Materials

5.5.2 Rigid Pavement Considerations

5.5.3 Pavement Drainage, Subdrainage, and Trenching

5.6 Soil Corrosivity

5.7 Liquefaction Potential

6.0 SITE PREPARATION, GRADING AND DRAINAGE

6.1 General Site Preparation

6.2 Building Pad Grading

6.3 General Fill

6.4 Select Fill

6.5 Drainage

7.0 CONSTRUCTION CONSIDERATIONS

7.1 Earthwork

7.2 Shallow Foundations

7.3 Utility Trench Construction

7.4 Rock Excavation Considerations

8.0 FIELD OBSERVATIONS & TESTING

8.1 Earthwork

8.2 Shallow Foundations

9.0 EXCAVATIONS

ECS Project No. 17:5539 Page 2

10.0 LIMITATIONS

APPENDICES

Appendix A – Figures

Site Location Diagram Exploration Location Diagram Site Geologic Map Surface Features Map Subsurface Profiles

Appendix B – Field Operations

Boring Logs Test Pit Logs Reference Notes for Boring Logs CAT 321D Specifications

Appendix C – Geotechnical Laboratory Testing

Laboratory Testing Summary

Appendix D – Analytical Laboratory Testing Sulfides Chlorides Sulfates pH Laboratory Resistivity Oxidation Reduction Potential

Appendix E – Photograph Log

Rock Core & Progress Photographs

ECS Project No. 17:5539 Page 3

EXECUTIVE SUMMARY

The following summarizes the main findings of the exploration, particularly those that may have a cost impact on the planned development. Further, our principal geotechnical recommendations are summarized. Information gleaned from the executive summary should not be utilized in lieu of reading the entire geotechnical report.

In general, the subject development is considered geotechnically feasible, provided the recommendations of this report are implemented in the design and construction of the project. The predominant geotechnical and geological constraints affecting the site development are the potential to encounter very hard bedrock and large boulders in excavations, the potential to encounter caving soils in excavations, and the soil frost heave potential for shallow foundations.

Earthwork, foundation and utility contractors should be prepared to encounter large boulders and very hard bedrock in some excavations, which will require rock excavation techniques and tooling for removal, and likely some limited blasting in confined excavations and where very hard basalt bedrock is present. Uneven excavations may result from areas containing these materials, which should be considered in estimation of construction material quantities.

The proposed service shelter and pump house building can be supported by conventional strip and spread footings. The net allowable bearing capacity for footings at least 12 inches wide and deep and founded on properly compacted soil is 3,000 psf. Exterior footings should be embedded at least 30 inches beneath existing grade for frost protection considerations.

Light duty pavements can consist of 2 inches asphaltic concrete on 8 inches base on a prepared subgrade, or 5 inches concrete on a prepared subgrade. Moderate duty pavements can consist of 2½ inches asphaltic concrete on 10 inches base on prepared subgrade, or 5½ inches concrete on a prepared subgrade. Heavy duty pavements can consist of 6½ inches concrete on a prepared subgrade.

ECS Project No. 17:5539 Page 4

1.0 INTRODUCTION

1.1 General

The purpose of this study was to provide geotechnical information for the design of foundations for the proposed structures, pavements and associated appurtenances and to provide commentary on excavation requirements anticipated for the proposed construction.

The recommendations developed for this report are based on project information provided by the Client. This report contains the results of our subsurface explorations and geotechnical laboratory testing programs, site characterization, engineering analyses, and recommendations for the design and construction of the proposed improvements.

1.2 Scope of Services

To obtain the necessary geotechnical information required for evaluation of subsurface soil conditions supporting the proposed structures, 30 soil borings were drilled and sampled to depths up to about 15 feet beneath the existing ground surface at the site. Additionally, 20 test pits were advanced to depths up to about 15 feet each beneath the existing ground surface at the site. The soil borings and test pits were performed at locations selected by ECS. A laboratory testing program was also implemented to characterize the physical and geotechnical engineering properties of the subsurface soils/rock.

This report discusses our exploratory and testing procedures, presents our findings and evaluations and includes the following:

A brief review and description of our field and laboratory test procedures and the results of testing conducted.

A review of surface features and site conditions.

A review of site geologic conditions.

A review of subsurface soil/rock stratigraphy with pertinent available physical properties.

Logs of our soil test borings and test pits.

A preliminary review of corrosion test results.

Recommendations for site preparation, grading and drainage.

Recommendations for foundation design and construction.

Recommendations for the structural design of pavements.

The scope of services for this project did not include an environmental assessment for determining the presence or absence of wetlands, or corrosive, hazardous or toxic materials in the soil, bedrock, surface water, groundwater, or air on or below, or around this site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes.

ECS Project No. 17:5539 Page 5

1.3 Authorization

Our services were provided in accordance with ECS Proposal No. 17-6783 dated December 15, 2020. This study was authorized via issuance of the Task Order for Gordon project No. 3336-0801 (Tasks Nos. 3336-0801-001A-002A, 3336-0801-001A-002B, and 3336-0801-001A-002C) dated March 4, 2021 pursuant to the Master Services Agreement between Gordon and ECS dated August 24, 2020.

2.0 PROJECT INFORMATION

2.1 Project Location

The project site is located at 2181 W. 1600 S., Cedar City, Utah. The location is depicted in the below Figure 2.1.1.

Figure 2.1.1 Site Location

2.2 Current Site Conditions

The site is currently undeveloped and contains sporadic trees, grassy underbrush, some unpaved drive paths, an existing corral, and some boulder outcrops. A surface feature map developed based on a visual review of the site in the field has been included in Appendix A for reference. The site’s topographic high and low are approximately EL. 6,664 feet and EL. 5,589 feet and the site slopes downward from west to east.

ECS Project No. 17:5539 Page 6

2.3 Proposed Construction

It is understood that the proposed cemetery development will include pre-placed crypts, grave sites, a service shelter, a pump house, retaining walls, memorial wall, pavements and flatwork, a boundary fence, and associated appurtenances. It is understood that some moderate cuts are planned for the proposed grave-site and crypts, as well as for the proposed storm drain line.

Structural loading information was not available at the time of this report and it is anticipated that the proposed structures will be supported by conventional strip and spread footings.

3.0 FIELD EXPLORATION

3.1 Field Exploration Program

The field exploration was planned with the objective of characterizing the project site in general geotechnical and geological terms and to evaluate subsequent field and laboratory data to assist in the determination of geotechnical recommendations.

3.1.1 Test Borings

The subsurface conditions were explored by drilling a total of 30 soil borings at the site. Twenty-eight (28) borings were drilled to depths of about 15 feet each and 2 borings were drilled to depths of 10 feet each beneath the existing ground surface. Drilling was performed using a truck-mounted drill rig, utilizing ODEX casing system and rock coring drilling methodology.

The boring locations were determined by the client and identified in the field by ECS personnel using a handheld GPS unit. The approximate elevations listed on the boring logs were determined based on the provided survey. Some degree of error in these values should be understood, and these elevations should be considered approximate. The approximate boring locations are shown on the Exploration Location Diagram attached in Appendix A.

Field logs of the soils/rock encountered in the borings were maintained by the drill crew. After recovery, each geotechnical soil/rock sample was removed from the sampler and visually classified.

Representative portions of each soil/rock sample were then bagged in plastic and placed in boxes and transported to our laboratory for further visual examination and laboratory testing. After completion of the exploratory operations, the boreholes were backfilled with the excess soil cuttings.

3.1.2 Test Pits

The subsurface conditions were explored by excavating 20 test pits. The test pits were excavated at the site to depths up to 15 feet, or to depths where the excavator experienced bucket refusal on large boulders or basalt bedrock. The test pit excavations were performed using a CAT 321 hydraulic excavator.

The test pit locations were determined and identified in the field by ECS personnel using a handheld GPS unit. The approximate elevations listed on the test pit logs were determined based on the provided survey. Some degree of error in these values should be understood, and these elevations

ECS Project No. 17:5539 Page 7 should be considered approximate. The approximate test pit locations are shown on the Exploration Location Plan attached in Appendix A.

The sizes of test pit excavations were variable depending on location and subsurface materials encountered. Test pit widths were generally about 2 feet to 4 feet wide depending on how even the excavation was due to cobbles and boulders present. Test pit lengths typically about 12 feet to 16 feet in total length, except for some approximately 20 feet to 25 feet in length excavations.

Field logs of the soils encountered in the test pits were maintained by an ECS representative. After recovery, each geotechnical sample was visually classified, and representative portions of each soil sample were then bagged in plastic and placed in bins and transported to our laboratory for further visual examination and laboratory testing. After completion of the exploratory operations, the test pits were backfilled with the excavated soils to the existing ground surface.

3.1.3 Penetration Tests and Sampling

Standard Penetration Tests (SPTs) were performed to obtain representative samples and penetration resistance measurements in general accordance with ASTM D 1586. Soil samples were obtained at various intervals with the 1.625-inch inside diameter, 2-inch outside diameter, Split Spoon sampler. The Split Spoon sampler was first seated 6 inches to penetrate any loose cuttings, and then was driven an additional 18 inches with blows of a 140-pound hammer falling 30 inches.

The number of hammer blows required to drive the sampler each 6 inch increment was recorded.

The penetration resistance “N-value” is defined as the number of hammer blows required to drive the sampler the middle 12 inches and is indicated on the test boring logs. In very dense materials such as weathered rock material, the SPT test is usually stopped after 50 blows from the hammer and the measurement is recorded as 50 blows per distance penetrated (i.e. 50 over 3 inches).

3.1.4 Rock Coring

Rock coring with the aid of an air compressor was performed using an Nx core barrel with an inside diameter of 2.125 inches. The rock core was measured to determine the Recovery Ratio (REC) and the Rock Quality Designation (RQD) index values. The REC value is equal to the total length of core recovered divided by the total length of core advance. The RQD value is defined as the percentage of core advance that is recovered in segments that are 4 inches or longer and is a qualitative index of the quality or physical integrity of the rock. Rock coring was performed in general accordance with ASTM D 2113. Rock core samples were placed in cardboard core boxes for transport to our laboratory.

3.2 Regional Geology & Faulting

The Interim geologic map of the Cedar City, 7.5-minute quadrangle indicates that the site is underlain by Cross Hollow Hills lava flows (Qbc1), which generally consists of dark-gray, crystal-poor trachybasalt. Individual flows are typically 10 to 30 feet thick. The approximate location of the site on the geologic map is provided in the Regional Geologic Map in Appendix A.

Based on a review of the Utah Geological Survey Quaternary Fault & Fold Map, the subject site is located in close proximity to the Hurricane Fault Zone (Cedar City section), and the Cross Hollow Hills faults. The site is located within an area with common seismic activity, typically of small to

ECS Project No. 17:5539 Page 8 moderate in size earthquakes. Based on the USGS 2018 Long-term National Seismic Hazard Map, the site appears to fall within a zone of moderate seismic hazard.

3.3 Subsurface Characterization

The following section provides generalized characterizations of the geology encountered during our subsurface exploration. For specific subsurface information, refer to the boring and test pit logs in Appendix B.

Information from the test borings and test pits indicates that the stratigraphy may generally consist of 2 distinguishable strata within the exploration depths of approximately 15 feet. A general description of each stratum is included in the table below.

STRATUM

RANGE OF

DEPTH (FT)

STRATUM DESCRIPTION

AND CLASSIFICATION

WC

RANGE

PI

RANGE

N

RANGE

UCS

RANGE

RQD

RANGE

REC

RANGE

WC

AVG.

PI

AVG.

N

AVG.

UCS

AVG.

RQD

AVG.

REC

AVG.

I 0 – (2-15)

OVERBURDEN & RESIDUAL

SOILS: (GC) Clayey Gravel, (GP & GP-GC) Gravel, (SC) Clayey Sand, (SP & SP-SC)

Sand, (CL) Lean Clay, Sandy Lean Clay, some (CH) Sandy

Fat Clay, boulders and cobbles noted throughout the site at various depths;

dark brown to reddish brown and gray to light brown and tan; loose to very dense, firm to very hard

1-18 17-39 5- 50/0”

251.5- 716.5**

38- 83**

72- 83**

8 25 63 467.5** 61** 77**

II* 2 – 14+

BEDROCK: Basalt; generally gray to black; very hard

50/3”- 50/0”

161.6- 1,890.9 0-100 0-100

-- -- 50/1” 743.3 59 71

*Encountered in borings B-01, B-03, B-07, B-12, B-15, B-17, B-22, & B-24 and test pit TP-05, and possibly test pits TP-10, TP- 12, TP-17, and TP-20. The bedrock materials in our exploration appeared to be basalt, and we did not identify alternate types of rock outside of the igneous rock category.

**UCS, RQD, and REC data for stratum I is representative of probable boulders encountered.

Notes: Depth- Soil Stratum depth from existing ground surface at the time of our geotechnical exploration WC- Water Content, % PI- Plasticity Index

N- Standard Penetration Test (SPT) value, field blows per foot UCS- Unconfined Compressive Strength, tsf

RQD- Rock Quality Designation, % REC- Rock Sample Recovery, %

ECS Project No. 17:5539 Page 9

Please refer to the attached boring logs, test pit logs, and laboratory data summary tables for a more detailed description of the subsurface conditions encountered, as the stratification descriptions above are generalized for presentation purposes.

3.4 Groundwater Observations

The borings and test pits were advanced using relatively dry excavation techniques to their completion depths, enabling the potential detection of the presence of groundwater. Groundwater was not encountered during drilling in the borings and test pits completed at the site. Upon completion of field operations, the boreholes and test pits were backfilled with excess excavated soils generated during our field operations.

The groundwater observations were typically made during and upon completion of the excavations.

A few of the initial borings were also checked several hours after completion, prior to backfilling.

Based on the granularity of the subsurface and the quantity of explorations completed, if groundwater was present in the proposed development area at the time of our exploration, it would have likely been encountered in at least one of those explorations, which it was not. If a water table was hypothetically present, it could influence foundation design values if within the influence zone of the footing, but the degree of influence would depend on how shallow the hypothetical groundwater table was in relation to bottom of footing.

It should be noted that water levels in open boreholes and test pits may require several hours to several days to stabilize depending on the permeability of the soils and that groundwater levels at the site may be subject to seasonal conditions, recent rainfall, drought or temperature effects. Clays and massive bedrock are generally not conducive to the presence of groundwater; however, gravels, sands and silts, and open fractures and solution features; where present, can store and transmit “perched” groundwater flow or seepage. Therefore, groundwater conditions should be evaluated just prior to and during construction.

4.0 GEOTECHNICAL LABORATORY TESTING

Samples were transported to the ECS laboratory where they were examined and visually classified by an ECS geotechnical engineer using the Unified Soil Classification System (USCS) in general accordance with ASTM D 2488. To aid in classification of the soils and determination of their selected engineering characteristics, a testing program was conducted on selected samples in general accordance with the following standards:

LABORATORY TESTING TEST STANDARD

Moisture Content ASTM D 2216

Atterberg Limits ASTM D 4318

Sieve Analysis ASTM D 1140 and ASTM D 422

Uniaxial Compressive Strength ASTM D7013

ECS Project No. 17:5539 Page 10

Results of the laboratory tests are included in the appendices on the boring and test pit logs and are presented on the laboratory test summary tables. Laboratory test results were used to classify the soils encountered as outlined by USCS in general accordance with ASTM D 2487. The USCS group symbols for each soil type are indicated in parentheses with the soil descriptions on the test logs.

Samples were returned to our laboratory in Austin, Texas. Samples not tested in the laboratory will be stored for a period of 60 days subsequent to submittal of this report and will be discarded after this period, unless we receive alternate instructions regarding their disposition.

5.0 DESIGN RECOMMENDATIONS

The following recommendations have been developed on the basis of the previously described project characteristics and subsurface conditions. If there are any changes to the project characteristics or if different subsurface conditions are encountered during construction, the recommendations of this report should be reviewed and revised. It is recommended that ECS conduct a geotechnical review of the project plans (prior to issuance for construction) to check to see that ECS’ geotechnical recommendations have been properly interpreted and implemented.

This report considers that building finished floor elevations will be within close proximity to existing grade. If finished grades deviate from existing grade, the recommendations provided below should be evaluated by our office.

5.1 Conventional Strip and Spread Footing Foundations

The proposed service shelter and pump house building can be supported by conventional strip and spread footings. The net allowable bearing capacity for footings at least 12 inches wide and 30 inches deep and founded on undisturbed native soils or properly compacted fill is 3,000 psf.

For resistance to lateral loads, a coefficient of friction of 0.35 between the base of the foundation elements and underlying bearing soils is recommended. In addition, for footings cast directly against undisturbed soil excavation sidewalls, a passive resistance equal to an equivalent fluid weighing 250 pounds per cubic foot acting against the foundation may be used to resist lateral forces, respectively. The recommended lateral resistance values are ultimate values and a suitable factor of safety should be used in design.

Where utility trenches or other excavations are located adjacent to foundations, the bottom of the footing should be located below an imaginary 1:1 (horizontal to vertical) plane projected upward from the nearest bottom edge of the utility trench.

The uplift resistance of a shallow foundation formed in an open excavation will be limited to the weight of the foundation concrete and the soil above it. For design purposes, the ultimate uplift resistance should be based on effective unit weights of 105 and 150 pcf for soil and concrete, respectively. This value should be reduced by an appropriate factor of safety to arrive at the allowable uplift load. If there is a chance of submergence, the buoyant unit weights should be used.

ECS Project No. 17:5539 Page 11

Post-construction total and differential (over a 40-foot distance) settlements for foundations constructed as recommended herein are anticipated to be about one (1) inch and one-half (½) inch, respectively. Contraction, control, or expansion joints should be designed and placed in various portions of the structure. Properly planned placement of these joints will assist in controlling the degree and location of material cracking which normally occurs due to material shrinkage, thermal effects, soil movements, and other related structural conditions.

Footing excavations should have firm bottoms and be free from slough prior to concrete or reinforcing steel placement. The foundation excavations should be observed by ECS prior to placement of reinforcing steel or concrete to observe the exposed ground conditions.

5.2 Non-Structural Slab-on-Grade Floors

The design of any grade-supported floor slab should take into consideration the interaction between the slab and the supporting soils in resisting moments and shears induced by applied loads. Several design methods use the modulus of subgrade reaction, k, to account for soil properties in design. The modulus of subgrade reaction is a spring constant that depends on the soil type, the degree of compaction and the moisture content. The k-value presented in the following table can be used for the design of flat, grade-supported floor slabs for this project. The k-value assumes that soil materials have been properly placed and compacted beneath the slab and that site drainage is good. Adequate construction joints and reinforcement should be provided to reduce the potential for cracking of the floor slabs due to differential movement.

SUBGRADE TYPE K-VALUE, PCI

Compacted Native Soils 125

6 Inches Compacted Aggregate Base Course (per Section 02721 of the UDOT 2017 Standard Specifications for Road and Bridge Construction) on Compacted

Native Soils

Where moisture sensitive floor coverings or equipment will be installed, we recommend that at least a 10 mil vapor retarder be used beneath the slab. The vapor retarder should conform to ASTM E1745, Class C or better and shall have a maximum water vapor permeance of 0.044 when tested in accordance with ASTM E96. Consideration to specifying a thicker, more durable vapor retarder should also be made where anticipated construction traffic dictates. If a vapor retarder is considered to provide moisture protection, special attention should be given to the surface curing of the slabs to minimize uneven drying of the slabs and associated cracking and/or slab curling.

Please refer to the latest edition of ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture- Sensitive Flooring Materials and ASTM E 1643 Standard Practice for Installation of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs for additional guidance on this issue.

5.3 Seismic Design Considerations

For the purposes of seismic design, a Site Class D (Very Stiff Soil) as defined in the 2018 International Building Code (IBC) / ASCE 7 is recommended for use at the project site. The site class is based on our review of geologic maps and literature and the subsurface conditions encountered in our soil borings. Using this site class and the location of the project site (lat. 37.6486°, long.

ECS Project No. 17:5539 Page 12

-113.0908°), probabilistic ground motion values were determined for this project and are shown in the following table:

PERIOD

(SECONDS)

DESIGN SPECTRAL RESPONSE

ACCELERATION PARAMETERS

SITE COEFFICIENT, FA SITE COEFFICIENT, FV

0.2 0.583 (SDS) 1.233 ---

1.0 0.288 (SD1) --- 1.959

It should be noted that our borings and test pits at the project site extended to maximum depths of about 15 feet below the ground surface, whereas ASCE 7 site classifications are based on characterization of the upper 100 feet of the soil profile. The seismic parameters shown in the above table are based on the information provided in the IBC manual on Tables 1613.3.3(1) and 1613.3.3(2), the site classification, and mapped spectral response accelerations at the short and one (1) second time periods. The above parameters were developed using the SEAOC/OSHPD seismic design maps web tool, and the 2015 IBC design provisions.

5.4 Retaining Walls

The magnitude of the lateral earth pressures on retaining walls is dependent upon the in-situ material behind the wall; and if displaced, the type of material used to backfill the “active zone” behind the wall. The magnitude of the earth pressure is also dependent upon whether the active zone is allowed to drain water freely. The active zone can be considered as the area behind the structure within a boundary created by a 45 degree angle extending from the outside edge of the foundation heel upward to the ground surface.

The lateral earth pressures for drained, level soil backfill are expressed in terms of pounds per cubic foot (psf/ft.) “equivalent fluid” weight applied in a triangular distribution pattern as listed below. If the walls are free to deflect or rotate slightly at the top they may be designed using “active” lateral earth pressures. If the walls are laterally restrained at the top, “at-rest” lateral earth pressures should be used for the retaining wall design. Where multiple material types are used within the active zone, the higher values below should be used. The equivalent fluid weights shown in the table do not include any safety factors and do not account for any surcharges. Lateral loads from uniform surcharges on the wall backfill can be calculated by multiplying the vertical surcharge by the below earth pressure coefficients and should be considered as rectangular loads acting on the full wall height. An increase of 1 pcf and 1.5 pcf should be added to the active and at-rest earth pressures; respectively, for each degree of inclination of backfill.

SOIL DESCRIPTION

TOTAL

UNIT

WEIGHT

(PCF)

ESTIMATED

FRICTION

ANGLE

ACTIVE

EARTH

PRESSURE

COEFFICIENT

AT-REST

EARTH

PRESSURE

COEFFICIENT

DRAINED

ACTIVE

EARTH

PRESSURE

(PSF/FT)

DRAINED

AT-REST

EARTH

PRESSURE

(PSF/FT)

Undisturbed or Compacted Native Soil

120 26 0.39 0.56 47 67

ECS Project No. 17:5539 Page 13

SOIL DESCRIPTION

TOTAL

UNIT

WEIGHT

(PCF)

ESTIMATED

FRICTION

ANGLE

ACTIVE

EARTH

PRESSURE

COEFFICIENT

AT-REST

EARTH

PRESSURE

COEFFICIENT

DRAINED

ACTIVE

EARTH

PRESSURE

(PSF/FT)

DRAINED

AT-REST

EARTH

PRESSURE

(PSF/FT)

Select Fill 120

0.36 0.53 43 64

Undisturbed/Cemented Basalt Bedrock

145 36 0.26 0.41 38 60

ASTM C33 Size #56, #57 or #467 Stone

0.33 0.50 37 55

Compacted Manufactured Sand

(< 8% Fines)

0.33 0.50 40 60

Compacted Aggregate Base

0.26 0.41 35 56

For sliding resistance, a coefficient of friction of 0.35 is recommended between the base of the foundation elements and the underlying soils. In addition, for footings cast directly against excavation sidewalls, a passive resistance equal to an equivalent fluid applying 250 pcf may be used to resist lateral forces for undisturbed soils. The passive resistance should be neglected in the upper 12 inches of soil unless the ground immediately in front of the footing is covered with concrete or other impervious pavement. The above values are ultimate values, and an appropriate safety factor should be used in design.

Retaining walls outside of prepared building areas can be supported by spread footing foundations at least 30 inches deep using an allowable bearing capacity of 3,000 psf at the bearing surface.

Footing excavations should have firm bottoms and be free from slough prior to concrete or reinforcing steel placement. The geotechnical engineer should be allowed to observe foundation excavations prior to reinforcing steel or concrete placement to confirm anticipated ground conditions.

Retaining walls should be waterproofed as required by the project architect. Subdrain systems and/or drainboard composites are recommended to reduce hydrostatic pressures on retaining walls. A subdrain system can consist of 4 inch perforated pipe placed at the base of the retaining wall and surrounded by ASTM C33 Size #57 stone completely wrapped in Mirafi 140N or 160N filter fabric, or equivalent reviewed by the geotechnical engineer. The drainrock wrapped in fabric should be at least 12 inches wide and extend from the base of the wall to within two feet of the ground surface. The upper two feet of backfill should consist of compacted native soil or other impervious pavement. The retaining wall drainage system should be sloped to outlet pipes draining away from the foundations and pumped to the surface as grades require. The use of drainage openings through the base of the wall (weep holes, etc.) is not recommended where the seepage could be a nuisance or otherwise adversely impact the property adjacent to the base of the wall. The subdrain system should be checked periodically to confirm functionality; failure of the subdrain system will affect the design lateral earth pressures and the retaining wall stability. If subdrain systems are

ECS Project No. 17:5539 Page 14 determined to not be practical, full hydrostatic pressures should be incorporated into the wall design.

As an alternative to a stone and fabric backdrain, a prefabricated drainage composite (drainboard) such as MiraDRAIN 2000, or reviewed equivalent, can be used behind the retaining wall. The drainboard should extend from the base of the wall to within two feet of the ground surface and should be installed in accordance with manufacturer specifications. A subdrain collector pipe surrounded with at least 5 cubic feet per foot size #57 stone (wrapped in filter fabric) should be installed at the base of the drainboard; or alternatively, an engineered system can be selected with sufficient capacity for direct connectivity to a closed pipe system. The groundwater should be conducted to an appropriate discharge or sump pump facility.

Where free-draining, clean granular materials will be used to backfill the walls, and where structures, pavements or other improvements will be located closely behind the retaining walls, it is recommended that all clean granular materials be separated from the soils and fills with the use of the above stated filter fabrics. The use of the filter fabric can greatly reduce the intrusion of the soils into the void spaces of the clean granular materials. Intrusion of the soils into the void spaces causes a net ground loss and can cause settlement of the ground surface and overriding improvements. It is recommended that soils classified as CH (Fat Clay) not be used within the active zone of retaining wall backfill.

The retaining wall backfill should be compacted and tested in maximum 8 inch lifts to be at least 95 percent of the standard Proctor maximum dry density (ASTM D 698) at moisture contents between optimum and plus three (+3) percentage points of the optimum moisture content.

5.5 Pavement Design

ECS has prepared the following recommendations for the design and construction of both flexible and rigid pavement systems for use on the subject project. The “AASHTO Guide for Design of Pavement Structures” published by the American Association of State Highway and Transportation Officials was used to develop the pavement thickness recommendations in this report. This method of design considers pavement performance, traffic, roadbed soil, pavement materials, environment, drainage and reliability. Each of these items is incorporated into the design methodology.

We have based our analysis on the following Equivalent Single Axle Load (ESAL ) information, which considers a load of 18 kip/per axle, and pavement-related subgrade design parameters, which are considered to be typical for the area. The AASHTO Guide for Design of Pavement Structures uses this as the basis of traffic design and provides a procedure to convert a mixed traffic stream of different axle loads into the standardized ESAL.

A CBR (California Bearing Ratio) value of 3.0 percent was selected for design purposes. The CBR value was estimated based on ECS’s knowledge and experience with similar soils and projects in this area.

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PAVEMENT DESIGN PARAMETERS

RELIABILITY 70

INITIAL SERVICEABILITY INDEX,

FLEXIBLE PAVEMENTS

4.2

INITIAL SERVICEABILITY INDEX,

RIGID PAVEMENTS

4.5

TERMINAL SERVICEABILITY INDEX,

ALL PAVEMENTS

2.0

STANDARD DEVIATION,

FLEXIBLE PAVEMENTS

0.45

STANDARD DEVIATION,

RIGID PAVEMENTS

0.35

Based on the design parameters listed above, we developed recommendations for “light duty,” “moderate duty” and “heavy duty” pavement sections. “Light duty” pavements are intended for general parking areas with passenger vehicles only and have an approximate capacity of 20,000 ESAL. “Moderate duty” pavements are intended for areas subject to channelized traffic and fire lanes and have an approximate capacity of 80,000 ESAL. “Heavy duty” pavements are intended for areas subject to heavier vehicles with extensive turning, starting and stopping, such as pavement aprons associated with trash enclosures, and have an approximate capacity of 250,000 ESAL. If the owner or other members of the design team feel that the ESAL values used for design are not appropriate, ECS should be notified in writing, so any new information can be reviewed, and if necessary, the pavement recommendations revised accordingly.

The minimum recommended thickness for both hot mixed asphalt concrete (HMAC) and reinforced Portland cement concrete (PCC) pavement sections are presented in the following table for the described “light”, “moderate” and “heavy” traffic conditions.

RECOMMENDED PAVEMENT SECTION OPTIONS

COMPONENT

LIGHT-DUTY

20,000 ESALS

MODERATE-

DUTY

80,000 ESALS

HEAVY-DUTY

250,000 ESALS

RIGID ASPHALT RIGID ASPHALT RIGID ASPHALT

Portland Cement Reinforced Concrete

(PCC)

5.0 in -- 5.5 in -- 6.0 in --

Hot Mixed Asphalt Concrete (HMAC) -- 2.0 in -- 2.5 in -- -- Aggregate Base (ABC) -- 8.0 in -- 10.0 in -- --

The pavement sections described above are for general-purpose usage for the anticipated subgrade conditions and were designed using the AASHTO Pavement and Analysis System. An aggressive

ECS Project No. 17:5539 Page 16 maintenance program to keep joints and cracks sealed to prevent moisture infiltration will help extend the pavement life.

We recommend that rigid pavement sections be used in all heavy truck traffic areas. The concrete pavement should extend throughout the areas that require extensive turning and maneuvering of the delivery vehicles, etc. Waste dumpster pads, loading areas and other heavily loaded pavement areas that are not designed to accommodate these conditions often experience localized pavement failures, particularly if flexible pavement sections are used.

5.5.1 Pavement Materials

Recommendations regarding material requirements for the various pavement sections are summarized below:

Portland Cement Concrete - Concrete used for paving should have a minimum compressive strength of 3,500 psi at 28-days. The air content at the point of placement should range from 3 to 6 percent. The concrete pavements should be reinforced and jointed per current ACI recommendations.

Hot Mix Asphalt Concrete (HMAC) Surface Course - The asphalt concrete surface course should be mixed, placed and compacted in conformance with the requirements of Sections 02741 and 02745 of UDOT 2017 Standard Specifications for Road and Bridge Construction.

Aggregate Base Course - Aggregate base should be placed in maximum 6 inch compacted lifts. The base materials should be compacted to at least 95 percent of the maximum dry density as determined by ASTM D 1557. Flexible base materials should be moisture conditioned to between minus two (-2) and plus three (+3) percentage points of the optimum moisture content. Aggregate base is recommended to consist of materials meeting the requirements of Section 02721 of the UDOT 2017 Standard Specifications for Road and Bridge Construction.

5.5.2 Rigid Pavement Considerations

Joints are typically placed in rigid pavements to control cracking, to facilitate construction, and to isolate a section of pavement from a structure or an adjacent pavement section. Joints used to control cracking are typically known as contraction or control joints as they are intended to control cracking that arises out of the shrinkage of concrete as it cures. Construction joints are used to provide clean breaks between pavement sections that result from the construction process.

Isolation joints (or expansion joints) are used to separate the pavement from other structures or pavements and typically include the use of compressible materials in the joint as opposed to contraction or construction joints. Contraction joints should be spaced no greater than 15 feet between the nearest parallel joints with joint depths of at least one-quarter (¼) of the slab thickness. Contraction and construction joints should be no wider than one-eighth (⅛) of an inch whereas isolation joints may be up to one (1) inch wide.

Steel reinforcement of concrete is typically not necessary for concrete pavements with construction or isolation (expansion) joint spacing closer than 15 feet. When joints are spaced greater than 15 feet, steel reinforcement can be used to control the width of cracks that form between these joints, ECS Project No. 17:5539 Page 17 such the fracture faces that form in the concrete are held together. Steel reinforcement is also used where subgrade conditions are not likely to provide uniform support to the concrete pavement.

Generally, sites with expansive soils present are often unable to provide such support to rigid pavement sections. Therefore, reinforcing steel can be used to span between construction and isolation (expansion) joints and should consist of at-minimum No. 3 bars spaced 18 inches on-centers each way. The rebar should be Grade 60 steel.

As with steel reinforcement, load transfer devices such as dowels are typically not necessary for most parking lots. However, in situations where heavy loads are present or the subgrade may not provide uniform support to the pavement, dowels are commonly used to transfer loads across joints. Smooth dowels can be used for this purpose and should be utilized as recommended in the following table.

DOWEL DESIGN INFORMATION

SLAB

THICKNESS, IN.

DOWEL

DIAMETER, IN.

MIN. DOWEL

EMBEDMENT

EACH SIDE, IN.

MIN. DOWEL

LENGTH, IN.

DOWEL SPACING

ON-CENTERS, IN

5.0 ⅝ 5 12 12

5.5 ¾ 6 14 12

6.0 ⅞ 7 16 12

The joint and reinforcing design of a rigid pavement system is largely a function of geometry for the pavement area. The proper length of concrete panels (defined as the distance between discontinuous pavement sections; e.g. between construction or isolation joints, or a combination of the two) and the location of contraction, construction, and isolation (expansion) joints are not included as a function of the above concrete pavement guidelines. Rather, these features should be determined based on the geometry and construction sequencing of the pavement. Actual joint spacing should be based on actual pavement areas and final panel lengths so that joints are evenly spaced. Joints should be designed to form approximately square panels where geometrically feasible.

The values provided herein are guidelines and the recommendations selected by the project civil engineer and any guidelines not provided or mentioned herein should not exceed the American Concrete Institute (ACI) 330R recommendations.

5.5.3 Pavement Drainage, Subdrainage, and Trenching

Longitudinal cracks and apparent distress due to expansive soils may appear in the pavement after construction and the introduction of landscape irrigation. These cracks and distress are not pavement failures with respect to traffic support, although they may be aesthetically undesirable.

In addition, without regular maintenance, the cracks can allow additional moisture intrusion and rapid degradation of the pavement section. The pavement sections are primarily designed to support the traffic and will not resist the forces generated by swelling soils.

Positive drainage should be provided on and around pavement areas to avoid ponding of water.

Irrigation of lawn and landscaped areas adjacent to the pavements should be moderate, with no

ECS Project No. 17:5539 Page 18 excessive wetting or drying of soils. If landscaped islands are provided, they should be designed to restrict excess water from migrating to the pavement subgrade by using self-contained beds, raised planter boxes, vertical moisture barriers, and/or edge drains. Curbs should extend through the base course and at least 4 inches into the underlying subgrade. Good perimeter surface drainage guiding surface water away from the pavement area is also recommended.

5.6 Soil Corrosivity

Corrosion of metals is an electrochemical process involving oxidation (anodic) and reduction (cathodic) reactions on metal surfaces. For metals in soil or water, corrosion is typically a result of contact with soluble salts found in the soil or water. This process requires moisture to form solutions of the soluble salts. Factors that influence the rate and amount of corrosion include the amount of moisture, the conductivity of the solution (soil and/or water), the hydrogen activity of the solution (pH), and the oxygen concentration (aeration). Other factors such as soil organic content, soil porosity, and texture indirectly effect corrosion of metals in soil by affecting the other factors listed above.

Characterizing the corrosivity of an environment is complicated due to the interaction of the variables described above. For example, a metal buried in an aerated or disturbed soil with a particular resistivity and soluble chloride concentration generally will not experience the same amount of corrosion as a similar metal placed in the same soil in a compacted, less aerated state.

Chloride ions from soil can lead to corrosion of steel reinforcement in concrete and steel structures by breaking down the normally present layer of oxides (passive layer) present on the steel surface.

A chloride concentration of 500 parts per million (ppm) or greater is generally considered highly corrosive to steel.

Similar to chlorides, sulfate ions may also lead to accelerated corrosion of steel reinforcement. In addition to causing metals to corrode, high amounts of sulfates are deleterious to concrete. Sulfates react with lime in the concrete to form expansive products that cause the concrete to soften and crack. Consequently, the concrete weakens. Cracked concrete is more susceptible to attack by water and other aggressive ions that may accelerate the process.

The presence of high acidity, pH of 5.5 or less, in soil or water is also considered a corrosive condition. Soil or water with a pH of 5.5 or less can react with the lime in concrete to form soluble reaction products that can easily leach out of the concrete. The result is a more porous, weaker concrete. Acidic conditions often cause discoloration of the concrete surface. A yellowish or rusted color distributed over the concrete surface should be investigated.

ACI 318 provides the following evaluation criteria with respect to concrete mix designs for concrete in contact with the ground, as well as additional detail regarding acceptable cement types:

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SULFATE

EXPOSURE

WATER-SOLUBLE

SULFATE IN SOIL,

PERCENTAGE BY WEIGHT

OR (MG/KG)

CEMENT TYPE

MAX. WATER

CEMENTITIOUS

RATIO BY

WEIGHT

MIN.

UNCONFINED

COMPRESSIVE

STRENGTH, PSI

Negligible 0.00-0.10 (0-1,000)

NA NA NA

Moderate 0.10-0.20

(1,000-2,000)

II, IP (MS), IS (MS) 0.50 4,000

Severe 0.20-2.00

(2,000-20,000)

V, IP (HS), IS (HS) 0.45 4,500

Very Severe Over 2.00 (20,000)

V plus pozzolan 0.45 4,500

Please see the below tabulated water soluble sulfate content results corresponding to the samples obtain from the borings locations at the indicated depths.

BORING LOCATION DEPTH

WATER SOLUBLE

SULFATE CONTENT

(MG/KG)

SULFATE EXPOSURE

B-3 4’-6’ 41.7 Negligible B-8 2’-4’ 113 Negligible

B-13 13’-15’ 6.45 Negligible B-19 2’-4’ 25.3 Negligible B-21 0’-2’ 13.4 Negligible B-27 4’-6’ 57.0 Negligible

Hence, in accordance with the above tables, the water-soluble sulfates are anticipated to have a negligible impact on buried concrete at the site.

Corrosion test results of soil samples obtained at the site can be evaluated based on ASTM A888 methods. Table X2.1, Soil-Test Evaluation, from the ASTM procedure is presented below. If the summed points are equal to 10, the soil should be considered corrosive to cast iron pipe.

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Soil Characteristics Points Soil Characteristics Points Resistivity, ohm-cm, based on single probe or water-saturated soil box. Redox Potential, mV

< 700 10 > +100 0 700 – 1,000 8 +50 to +100 3.5 1,000 – 1,200 5 0 to 50 4 1,200 – 1,500 2 Negative 5 1,500 – 2,000 1 > 2,000 0 Sulfides Positive 3.5 pH Trace 2 0 – 2 5 Negative 0 2 – 4 3 4 – 6.5 0 Moisture

6.5 – 7.5 0 Poor drainage, continuously wet 2

7.5 – 8.5 0 Fair drainage, generally moist 1 > 8.5 3 Good drainage, generally dry 0

Please see the below tabulated resistivity, pH, redox potential, sulfide, and chloride results corresponding to the samples obtain from the borings locations at the indicated depths.

BORING

LOCATION

DEPTH

RESISTIVITY

(OHM-CM)

pH

REDOX

POTENTIAL

(MV)

SULFIDES

(MG/KG)

CHLORIDES

(MG/KG)

ASSUMED

DRAINAGE

TOTAL

POINTS

B-3 4’-6’ 4030 8.76 361 3.14 15.8 Fair 6 B-8 2’-4’ 2470 8.61 279 4.10 43.1 Fair 6

B-13 13’-15’ 6010 9.16 396 2.05 15.0 Fair 6 B-19 2’-4’ 4610 8.53 413 <1.61 13.5 Fair 6 B-21 0’-2’ 4220 8.16 421 4.38 5.83 Fair 3 B-27 4’-6’ 4760 8.73 419 4.53 7.03 Fair 6

Hence, in accordance with the above table, soils at the site a generally considered to have a low to moderate potential for corrosion. Our sample receipt was delayed by the freeze our region experienced during the time of this subsurface exploration. The DHL lab report included in Appendix D notes that sulfide testing occurred outside of the EPA recommended holding time. The maximum points sulfides contribute to the corrosion analysis is 3.5, and under a worst-case scenario of assigning 3.5 points to each sample for positive sulfides, the total corrosion points for each sample analyzed would still be under 10 points (10 points or greater indicates a corrosive condition to cast iron pipes).

These results are preliminary, and provide information on the specific soils sampled and tested.

Other soil at the site, and imported fill materials, may be more or less corrosive. Water-soluble sulfate concentrations can vary due to the addition of fertilizer, irrigation and other possible development activities. Providing a detailed assessment of the corrosion potential of the site soil is not within our scope of work. A qualified corrosion specialist should be contacted if a detailed evaluation is required.

ECS Project No. 17:5539 Page 21

5.7 Liquefaction Potential

Liquefaction is the phenomenon of soil behaving like a liquid due to rapid loading conditions that result in an increase in pore water pressure and a decrease in effective…