5-26B-083 UES Geotech Report.pdf

REPORT OF GEOTECHNICAL

CONSULTING SERVICES

Golden Holiday Lift Station & Force Main Improvements NW 16th Ln. & NW Old Blichton Rd.

Ocala, Marion County, FL

UES Project No. A25140.00817.000 UES Report No. 2160163

Prepared for:

Ardurra 925 SE 17th Street, Suite A

Ocala, FL 34471

Prepared by:

UES Professional Solutions, LLC 4475 SW 35th Terrace

Gainesville, Florida 32608

(352) 372-3392

December 5, 2025

4475 Southwest 35th Terrace - Gainesville, FL 32608. (352) 372-3392 � Fax (352) 336-7914 www.teamues.com

December 5, 2025

Ardurra 925 SE 17th Street, Suite A Ocala, FL 34471

Attention: Mr. Mitchell Chauncey, P.E.

Reference: Report of Geotechnical Consulting Services

Golden Holiday Lift Station/Force Main Improvements NW 16th Ln. & NW Old Blichton Rd.

Ocala, Marion County, FL

UES Project No. A25140.00817 UES Report No. 2160163

Dear Mr. Chauncey:

UES Professional Solutions, LLC (UES) has completed the geotechnical exploration program for this project in accordance with the authorized scope of services as summarized in UES Proposal No. 2070746, dated February 13, 2024.

This report presents the results of our subsurface field exploration and laboratory soil testing programs, an engineering interpretation of these with respect to the project characteristics described to us, discussion of groundwater considerations, and suitability of shallow subsurface soils as backfill material as well as geotechnical engineering recommendations for soil design parameters for the proposed project.

We appreciate the opportunity to have assisted you on this project and look forward to a continued association. Please contact our office if you have any questions, or to assist your office with the remaining phases of project design and construction.

Respectfully submitted, UES PROFESSIONAL SOLUTIONS, LLC

Certificate of Authorization 549

Timothy E. Kwiatkowski, P.E. Eduardo Suarez, P.E.

Project Geotechnical Engineer Senior Geotechnical Engineer Florida P.E. No. 86444 Florida P.E. No. 60272 Date:

This item has been electronically signed and sealed by Eduardo Suarez, PE on the date adjacent to the seal using Digital Signature.

Printed copies of this document are not considered signed and sealed and the signature must be verified on any electronic copies.

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION

1.1 GENERAL

2.0 SCOPE OF SERVICES

2.1 PROJECT DESCRIPTION

2.2 PURPOSE

2.3 FIELD EXPLORATION

2.3.1 Standard Penetration Test (SPT) Borings

2.4 LABORATORY TESTING

2.4.1 Visual Classification

2.4.2 Index Testing

3.0 FINDINGS

3.1 REGIONAL GEOLOGY

3.2 SOIL SURVEY

3.3 SURFACE CONDITIONS

3.4 SUBSURFACE CONDITIONS

3.5 GROUNDWATER DEPTH

3.6 LABORATORY TESTING

3.6.1 Percent Passing No. 200 Sieve

3.6.2 Moisture Content

3.6.3 Atterberg Limits

4.0 RECOMMENDATIONS

4.1 GENERAL

4.2 GEOTECHNICAL CONSIDERATIONS

4.3 GROUNDWATER CONSIDERATIONS

4.4 DEWATERING

4.5 TRENCH BEDDING AND BACKFILLING RECOMMENDATIONS

4.6 SUITABILITY OF EXCAVATED SOILS

4.7 SOIL DESIGN PARAMETER RECOMMENDATIONS

4.8 LIFT STATION FOUNDATION DESIGN RECOMMENDATIONS

5.0 REPORT LIMITATIONS

APPENDIX A

Boring Location Plan ..................................................................................................... A-1 Boring Logs ........................................................................................................ A-2 to A-4 Key to Boring Logs ........................................................................................................... A

APPENDIX B

Important Information About Your Geotechnical Engineering

Report, Constraints and Restrictions, General Conditions ............................................... B

LIST OF TABLES

Table 1 – Relevant Engineering Index Properties of Arredondo Soils Table 2 – Relevant Engineering Index Properties of Martel Soils Table 3 – Relevant Engineering Index Properties of Kendrick Soils Table 4 – Laboratory Soil Test Results Table 5 – Soil Design Parameters

Project No.: A25140.00817 Report No.: 2160163

Date: December 5, 2025

EXECUTIVE SUMMARY

We have prepared this executive summary solely to provide a general overview. Do not rely on this executive summary for any purpose except that for which it was prepared. Rely on the full report for information about findings, recommendations, and other concerns.

Project Location and Description

The project site is located within right of ways on NW 16th Lane, NW 32nd Avenue, and NW Blichton Road in Ocala, Marion County, Florida. The proposed construction includes the abandonment of an existing wastewater treatment facility, and replaced with a lift station. In addition, a force main will be constructed and installed to the City sewer system. The force main crossing will be achieved by trenchless crossing method, Horizontal Directional Drilling (HDD).

Our office was provided with a plan and profile, which depicts the existing and proposed grades, proposed pipe elevations, as well as the soil boring locations. Our office was not provided with any other related information other than that discussed herein. If our understandings and assumptions of project issues are incorrect our conclusions and recommendations will not be considered valid until we have had the opportunity to review all pertinent issues.

Soil and Groundwater Conditions

Based on a review of the Soil Survey of Marion County, Florida the project site is located within Arredondo, Martel and Kendrick soils. The soil test borings generally encountered layers of very loose to medium dense silty-clayey sands [SM/SM-SC]/[A-2-4] to depths of 0 to 7 feet followed by clayey sand to clay [SC/CH]/[A-2-6/A-7] to depths of 4 to 20 feet. Below the clay stratum, the soil test borings generally encountered limestone to the maximum boring termination depths of 25 feet below existing grade. It should be noted that shallow limestone was encountered within soil borings, which could make excavation/construction operations in these areas difficult.

Geotechnical Considerations – Soil Design Parameters

Based on our exploration, the primary geotechnical considerations for the construction of the proposed lift station and pipeline improvements are the laterally discontinuous condition of the soil strata, the presence of shallow deposit of limestone, potentially expansive clayey soils [A-2-6/A- 6/A-7], and loose sandy layers in the shallow subsurface profile.

It is understood the proposed lift station wet well structure will have an approximate diameter of 5 feet, and bear at a depth of approximately 15 feet. The lift station foundation structure may bear within the limestone stratum. Hard lenses of limestone may be encountered that require greater than normal removal techniques. If limestone is found during the foundation excavations, we recommend that all excavation cut into the limestone deposit extend at least 2 feet below the required bottom elevation of the excavation. The bottom of the lift station should be visually inspected by the Geotechnical Engineer. The Geotechnical Engineer should be contacted if dissimilar bearing soil conditions, such as clayey sand/soil-rock mix versus cemented limestone, are exposed beneath the bottom of the structure. Removal of cemented limestone may be required if dissimilar bearing conditions are encountered within 2 feet of the proposed bottom of the structure.

The subgrade after excavation in some areas may include silty-clayey sands, which will be difficult to compact. If these soils are soft in nature, they should be over-excavated and removed under the direction of the testing agency representative. Alternatively, approximately 6 to 12 inches of #57 stone (gravel) may be placed at the bottom and compacted to stabilize the subgrade.

It should be noted that shallow limestone boulders/layers were encountered within soil borings.

Utility trenches may encounter limestone boulders/layers resulting in difficult excavation and dewatering operations. Rock, boulders and any unyielding material should be removed to a depth of 12 inches below the bottom of the pipe elevations.

If utilized for backfill, the silty/clayey sandy soils (A-2-4/A-2-6) may require stringent moisture control during compaction, particularly during rainy periods, which could cause delays in construction time. The moisture content of these soils should not be higher than the optimum during placement and compaction in order to reduce the potential for moisture related instability.

These soils may require some spreading and aeration time to reduce moisture content, if allowed to become saturated during earthwork activities or are located below the ground water table. Our past experience has shown that successful use of marginal soils is highly dependent upon the contractor’s ability to work with these types of soils, and weather conditions. It should be anticipated that undercutting of clayey soils [A-6/A-7] in bedding zones and placement of appropriate bedding material could be needed to stabilize the subgrade soils and obtain a stable workable platform.

Based on the results of our exploration, we consider the subsurface soils suitable for support of the proposed pipeline structures when constructed on a properly designed system. Horizontal Directional Drilling (Directional Bore) should be performed in general accordance with the appropriate section of the current edition of the Florida Department of Transportation (FDOT) Standard Specifications for Road and Bridge Construction. Further, bore hole diameter, drilling fluid mixture, materials and equipment should follow requirements specified in Section 555 Directional Bore of FDOT standards. Ground conditions can change unexpectedly, from soft soil to hard rock within a short distance that may require adjustments to the process and tooling. The geotechnical information presented herein is provided to aid the Horizontal Directional Drilling (HDD) construction, and design process in the area, and is a representation of the soil conditions encountered.

The clayey sandy soils may require stringent moisture control during compaction, particularly during rainy periods, which could cause delays in construction time. The moisture content of these soils should not be higher than the optimum during placement and compaction in order to reduce the potential for moisture related instability. These soils may require some spreading and aeration time to reduce moisture content if allowed to become saturated during earthwork activities. Our past experience has shown that successful use of marginal soils is highly dependent upon the contractor’s ability to work with these types of soils, and weather conditions.

1.0 INTRODUCTION

1.1 GENERAL

In this report, we present the results of the geotechnical exploration within the limits of the proposed lift station/manholes and force main improvements in Ocala, Marion County, Florida.

We have divided this report into the following sections:

SCOPE OF SERVICES - Defines what we did FINDINGS - Describes what we found RECOMMENDATIONS - Describes what we encourage you to do LIMITATIONS - Describes the restrictions inherent in this report APPENDICES - Presents support materials referenced in this report

2.0 SCOPE OF SERVICES

2.1 PROJECT DESCRIPTION

The project site is located within right of ways on NW 16th Lane, NW 32nd Avenue, and NW Blichton Road in Ocala, Marion County, Florida. The proposed construction includes the abandonment of an existing wastewater treatment facility, and replaced with a lift station. In addition, a force main will be constructed and installed to the City sewer system. The force main crossing will be achieved by trenchless crossing method, Horizontal Directional Drilling (HDD).

Our office was provided with a plan and profile, which depicts the existing and proposed grades, proposed pipe elevations, as well as the soil boring locations. Our office was not provided with any other related information other than that discussed herein. If our understandings and assumptions of project issues are incorrect our conclusions and recommendations will not be considered valid until we have had the opportunity to review all pertinent issues.

Our recommendations are based on the above conditions. If our understandings and assumptions of project issues are incorrect our conclusions and recommendations will not be considered valid until we have had the opportunity to review final project design information. The above constitutes all of the project information provided to our office at the time of this Report preparation.

2.2 PURPOSE

The purposes of this exploration were:

To explore the prevailing site subsurface conditions within the proposed lift station/manholes and force main improvements, To perform a series of laboratory tests on selected subsurface soil specimens, recovered from the field exploration program to assist with engineering soil classifications, To evaluate and discuss typical geotechnical issues deemed relevant to proposed trenchless pipe installation, To provide geotechnical engineering recommendations for seasonal high groundwater table, groundwater dewatering consideration, suitability of encountered subsurface soils as backfill material, and trench backfilling procedures, To present soil design parameters recommendations for the proposed main crossing, trenchless pipe installation, To prepare geotechnical site preparation and foundation design parameters for the proposed lift station/manhole structures.

This report presents an evaluation of site conditions on the basis of traditional geotechnical procedures for site characterization. The recovered samples were not examined, either visually or analytically, for chemical composition or environmental hazards. UES would be pleased to perform these services, if you desire.

Our exploration was confined to the zone of soil likely to be stressed by the proposed construction. Our work did not address the potential for surface expression of deep geological conditions. This evaluation requires a more extensive range of field services than performed in this study. We will be pleased to conduct an investigation to evaluate the probable effect of the regional geology upon the proposed construction, if you desire.

2.3 FIELD EXPLORATION

The field geotechnical testing activities were started and completed on November 11, 2025. Field tests for the geotechnical study included three (3) soil test borings to depths of 20 to 25 feet below the ground surface within the limits of the proposed alignment of the lift station and force main improvements.

The borings were performed at readily accessible locations. The soil test boring locations are shown in the attached Boring Location Plan drawing. The test quantities, locations, and depths were selected by UES. The actual test locations shown are approximate and were staked in the field by UES engineering personnel using existing landmarks and site features. The boreholes were grouted upon field work completion.

2.3.1 Standard Penetration Test (SPT) Borings

Penetration tests were performed in accordance with ASTM Procedure D-1586, Penetration Test and Split-Barrel Sampling of Soils. This test procedure generally involves driving a 1.4-inch I.D.

split-tube sampler into the soil profile in six inch increments for a minimum distance of 18 inches using a 140-pound hammer free-falling 30 inches. The total number of blows required to drive the sampler the second and third 6-inch increments is designated as the N-value, and provides an indication of in-place soil strength, density and consistency.

Representative portions of the subsurface soil samples recovered were transported to our Gainesville soils laboratory. The soil samples were visually classified by an experienced geotechnical engineer. The results of the classification and stratification have been shown on the attached Boring Logs and summarized later in this Report. It should be noted that soil conditions might vary between soil test boring locations, and between the subsurface soil strata interfaces which have been shown on the Boring Logs. The soil test boring data reflect information from the specific test locations only.

This Report presents an evaluation of site conditions on the basis of traditional geotechnical procedures for site characterization. The recovered samples were not examined, either visually or analytically, for chemical composition or environmental hazards.

2.4 LABORATORY TESTING

2.4.1 Visual Classification

The soil samples recovered from the soil test borings were returned to our laboratory where an engineer visually reviewed the field descriptions in accordance with ASTM D-2488. Following our review of the field boring logs and samples we classified the soil borings in accordance with the current Unified Soil Classification System (USCS) and AASHTO Soil Classification System. We then selected representative soil samples for laboratory testing and later refined some of the classifications based on the laboratory tests.

2.4.2 Index Testing

Laboratory testing was performed on selected samples of the soils recovered from the field exploration to evaluate soil composition and properties. Testing was performed in accordance to ASTM procedures and included Atterberg Limits (ASTM D-4318), Percent passing No. 200 Sieve (ASTM D-1140), and natural moisture content (ASTM D-2216). The test results have been presented on the attached Boring Logs.

3.0 FINDINGS

3.1 REGIONAL GEOLOGY

The general geology of Marion County is characterized by a surface veneer of Pleistocene and Pliocene sands and sandy clays overlying the Miocene age Hawthorn Group, a highly variable mixture of interbedded quartz sands, clays, carbonates, pebbles and grains occurring in thickness of up to 150 feet. Underlying the Hawthorn Group is the upper Eocene age Ocala Formation, occurring as a uniform limestone, which is approximately 200 feet thick and overlies the Eocene age Avon Park Formation, which can be up to 500 feet thick. Both the Ocala and Hawthorn Formations dip to the northeast by approximately one degree. The surface of the upper Floridan Aquifer in the general project site area is estimated on the order of +40 feet, NGVD.

3.2 SOIL SURVEY

The United Sates Department of Agriculture (USDA) Soil Survey of Alachua County, Florida describes the near-surface soil profile in the general project area as Arredondo, Martel, and Kendrick soils. Arredondo sand is described as nearly level to gently sloping and well drained with a water table at a depth of more than 72 inches. Relevant engineering index properties for Arredondo soils have been summarized below in Table 1.

Table 1 – Relevant Engineering Index Properties of Arredondo Soils

Depth, Inches

Texture

Classification

% Passing #200 Sieve

Plasticity Index

Shrink-swell Potential

Permeability

0 – 65 Sand SP-SM, SM 5 – 15 NP Low 6.0 – 20 in/hr

65 – 70 Loamy sand, loamy fine sand, sandy loam

SM, SM-SC 13 – 25 NP – 7 Low 2.0 – 6.0 in/hr

70 – 90 Sandy loam, fine sandy loam, sandy clay loam

SM-SC, SC 20 – 40 4 – 20 Low 2.0 – 6.0 in/hr

Martel soil is described as nearly level and very poorly drained soils, with a high water table that is within a depth of 10 inches of the surface for 6 to 12 months during most years. Most areas are covered with water for 6 months or more during most years. Relevant engineering index properties for Martel soils have been summarized below in Table 2.

Table 2 – Relevant Engineering Index Properties of Martel Soils

#200 Sieve

Plasticity Index

0 – 19 Sandy clay loam SC, CL 36 – 55 8 – 20 Moderate 0.6 – 2.0 in/hr

19 – 72 Sandy clay, clay CL, CH 51 – 70 30 – 45 High < 0.06 in/hr

Kendrick soil is described as nearly level to gently sloping and well drained, with a high water table that is at a depth of more than 72 inches. Relevant engineering index properties for Kendrick soils have been summarized below in Table 3.

Table 3 – Relevant Engineering Index Properties of Kendrick Soils

#200 Sieve

Plasticity Index

0 – 26 Loamy sand SM 15 – 25 NP Low 6.0 – 20 in/hr

26 – 45 Sandy clay loam SC 25 – 40 11 – 18 Low 0.6 – 2.0 in/hr

45 – 79 Sandy clay loam, sandy clay

SC 25 – 45 11 – 20 Low 0.6 – 2.0 in/hr

79 – 83 Sandy clay loam, sandy loam

SM-SC, SC 25 – 35 4 – 18 Low 0.6 – 2.0 in/hr

3.3 SURFACE CONDITIONS

UES engineering personnel visited the project site prior to and during the performance of the field portion of this geotechnical study. The project limits generally run along the NW Old Blichton Road right-of-way, from NW 27th Avenue to NW 32nd Avenue, with a lift station located along NW 16th Lane. Across the proposed project, the site grades generally range between approximately elevations from +70 feet at the proposed lift station to +85 feet adjacent to NW 27th Avenue. The above constitutes all of the project information provided to our office at the time of this report preparation.

3.4 SUBSURFACE CONDITIONS

The soil test borings performed beneath the proposed alignment were reviewed to evaluate the subsurface soil strata lateral continuity and uniformity, both parameters that would have an impact in the structural backfill material, pipe bedding, trench backfilling and trenchless operations. Soil classifications and descriptions for this geotechnical study are based both on the results of the laboratory soil testing programs and on visual classification of soil specimens by the Geotechnical Engineer. The subsurface soil conditions found in the soil test borings have been summarized in Appendix A and described below.

The outlined soil profile represents the dominant soil conditions. Some deviations were encountered. Individual boring logs should be reviewed for a more detailed soil description. It should be anticipated that soil conditions will vary around and between boring locations.

The soil test borings generally encountered layers of very loose to medium dense silty-clayey sands [SM/SM-SC]/[A-2-4] to depths of 0 to 7 feet followed by clayey sand to clay [SC/CH]/[A-2- 6/A-7] to depths of 4 to 20 feet. Below the clay stratum, the soil test borings generally encountered limestone formation to the maximum boring termination depths of 25 feet below existing grade. It should be noted that shallow limestone was encountered within soil borings, which could make excavation/construction operations in these areas difficult.

3.5 GROUNDWATER DEPTH

The groundwater level was not encountered below existing grades along the boring locations at the time of our exploration. It should be noted that the groundwater level may not have been fully stabilized in the boreholes when the readings were taken upon work completion. The stabilized groundwater levels may have been impacted by the drilling process. Fluctuations of the groundwater levels should be expected to occur seasonally as a result of rainfall, surface runoff, and nearby construction activities

3.6 LABORATORY TESTING

The soil samples recovered from the field exploration program were placed in plastic containers and returned to our soils laboratory, where the Geotechnical Engineer visually classified the samples. Laboratory soil tests are performed to aid in the classification of the soils, and to help in the evaluation of engineering characteristics of the soils. Representative soil samples were selected for percent fines determination, Atterberg Limits, and moisture content testing. The test results have been presented on the attached Boring Logs and summarized in Table 4.

Table 4 – Laboratory Soil Test Results

Soil Boring Sample Depth Type of Test Results Soil Description

B-1 3 feet % Finer #200 53 %

Sandy Clay Moisture Content 24 %

B-2 4.5 feet % Finer #200 17 %

Silty-Clayey Sand Moisture Content 9 %

B-2 14 feet

% Finer #200 26 %

Clayey Sand Moisture Content 14 %

Atterberg Limits LL = 30 , PI = 18

B-3 3 feet % Finer #200 65 %

Sandy Clay Moisture Content 35 %

B-3 9 feet

% Finer #200 92 %

Clay Moisture Content 43 %

Atterberg Limits LL = 97 , PI = 72

3.6.1 Percent Passing No. 200 Sieve

Certain recovered soil samples were selected to determine the percentage of fines. In these tests the soil sample was dried and washed over a No. 200 mesh sieve. The percent of soil by weight passing the sieve was the percentage of fines or portion of the sample in the silt and clay size range. This test was conducted in accordance with ASTM Procedure D-1140, Amount of Material in Soils Finer Than the #200 Sieve.

3.6.2 Moisture Content

Certain recovered soil samples were selected to determine the moisture content. These tests were conducted in accordance with ASTM Procedure D-2216. The soil moisture content was the ratio of the weight of water in the soil mass to the dry weight of the soil mass. Moisture content was measured by drying the moist material to a constant mass in a drying oven controlled at 105 degrees Celsius and to use this value as the mass of water in the test specimen. The moisture content was expressed as a percent of the oven dried soil mass.

3.6.3 Atterberg Limits

Certain recovered soil samples were selected for Atterberg Limits testing to determine the soil plasticity characteristics. The soil’s Plasticity Index (PI) is the range of moisture content over which the soil deforms as a plastic material. It is bracketed by the Liquid Limit (LL) and the Plastic Limit (PL). The LL is the moisture content at which the soil will flow as a heavy viscous fluid. The PL is the lowest moisture content at which the soil is sufficiently plastic so as to be manually rolled into a 1/8-inch diameter thread. The test is conducted in accordance with ASTM Procedure D- 4318, Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.

4.0 RECOMMENDATIONS

4.1 GENERAL

The following recommendations are made based upon a review of the attached soil test data, our understanding of the construction, and experience with similar projects and subsurface conditions.

It should be anticipated that subsurface conditions will vary between soil borings. If plans change from those discussed previously, we request the opportunity to review and possibly amend our recommendations with respect to those changes. Additionally, if subsurface conditions are encountered during construction, which were not encountered in the borings, report those conditions immediately to us for observation and recommendations.

In this section of the report, we present our detailed recommendations for groundwater control, suitability of encountered subsurface soils as backfill material, pipe bedding and trench backfilling operations, site preparation, and construction related services.

4.2 GEOTECHNICAL CONSIDERATIONS

Based on our exploration, the primary geotechnical considerations for the construction of the proposed lift station and pipeline improvements are the laterally discontinuous condition of the soil strata, the presence of shallow deposit of limestone, potentially expansive clayey soils [A-2-6/A- 6/A-7], and loose sandy layers in the shallow subsurface profile.

It is understood the proposed lift station wet well structure will have an approximate diameter of 5 feet, and bear at a depth of approximately 15 feet. The lift station foundation structure may bear within the limestone stratum. Hard lenses of limestone may be encountered that require greater than normal removal techniques. If limestone is found during the foundation excavations, we recommend that all excavation cut into the limestone deposit extend at least 2 feet below the required bottom elevation of the excavation. The bottom of the lift station should be visually inspected by the Geotechnical Engineer. The Geotechnical Engineer should be contacted if dissimilar bearing soil conditions, such as clayey sand/soil-rock mix versus cemented limestone, are exposed beneath the bottom of the structure. Removal of cemented limestone may be required if dissimilar bearing conditions are encountered within 2 feet of the proposed bottom of the structure.

The subgrade after excavation in some areas may include silty-clayey sands, which will be difficult to compact. If these soils are soft in nature, they should be over-excavated and removed under the direction of the testing agency representative. Alternatively, approximately 6 to 12 inches of #57 stone (gravel) may be placed at the bottom and compacted to stabilize the subgrade.

It should be noted that shallow limestone boulders/layers were encountered within soil borings.

Utility trenches may encounter limestone boulders/layers resulting in difficult excavation and dewatering operations. Rock, boulders and any unyielding material should be removed to a depth of 12 inches below the bottom of the pipe elevations.

If utilized for backfill, the silty/clayey sandy soils (A-2-4/A-2-6) may require stringent moisture control during compaction, particularly during rainy periods, which could cause delays in construction time. The moisture content of these soils should not be higher than the optimum during placement and compaction in order to reduce the potential for moisture related instability.

These soils may require some spreading and aeration time to reduce moisture content, if allowed to become saturated during earthwork activities or are located below the ground water table. Our past experience has shown that successful use of marginal soils is highly dependent upon the contractor’s ability to work with these types of soils, and weather conditions. It should be anticipated that undercutting of clayey soils [A-6/A-7] in bedding zones and placement of appropriate bedding material could be needed to stabilize the subgrade soils and obtain a stable workable platform.

Based on the results of our exploration, we consider the subsurface soils suitable for support of the proposed pipeline structures when constructed on a properly designed system. Horizontal Directional Drilling (Directional Bore) should be performed in general accordance with the appropriate section of the current edition of the Florida Department of Transportation (FDOT) Standard Specifications for Road and Bridge Construction. Further, bore hole diameter, drilling fluid mixture, materials and equipment should follow requirements specified in Section 555 Directional Bore of FDOT standards. Ground conditions can change unexpectedly, from soft soil to hard rock within a short distance that may require adjustments to the process and tooling.

The clayey sandy soils may require stringent moisture control during compaction, particularly during rainy periods, which could cause delays in construction time. The moisture content of these soils should not be higher than the optimum during placement and compaction in order to reduce the potential for moisture related instability. These soils may require some spreading and aeration time to reduce moisture content if allowed to become saturated during earthwork activities. Our past experience has shown that successful use of marginal soils is highly dependent upon the contractor’s ability to work with these types of soils, and weather conditions.

4.3 GROUNDWATER CONSIDERATIONS

The groundwater table will fluctuate seasonally depending upon local rainfall. The rainy seasons in North Central Florida are normally between June and September and December and February.

Based upon our review of regional hydrogeology and the Marion County Soil Survey, we estimate the seasonal high groundwater table will occur at depths of more than 6 feet below the ground surface within the pipeline improvement soil borings; however, stormwater can perch on top of clayey sands when sandy soils are present at the surface. Isolated areas with a transient perched groundwater should be expected to occur. The perched groundwater will be a transient condition, directly related to rainfall, irrigation and site grading.

We recommend positive drainage be established and maintained on the site during construction.

We further recommend permanent measures be constructed to maintain positive drainage from the site throughout the life of the project. Temporary dewatering may be required, particularly during deeper excavation required for the installation of the utility pipes. We recommend that the groundwater table be maintained at least 24 inches below all earthwork and compaction surfaces during construction.

The exposed subgrade soils consisting of silty and clayey sands will most likely result in saturated and pumping conditions due to the perched or standing water conditions. Further, short periods of intense rainfall can saturate surface soils, leading to instability during compaction and placement.

In the event that heavy rainfall during construction activities resulted in unstable saturated conditions, the exposed saturated subgrade soils should be windrowed and aerated to reduce the moisture contents prior to further earthwork operations. Alternatively, the saturated soils could be over excavated and backfilled with compacted structural fill.

4.4 DEWATERING

Based on the groundwater level conditions encountered and expected on this project site, dewatering may not be required to achieve the necessary excavation, construction, backfilling and compaction requirements presented in some of the preceding report sections. If necessary, dewatering should be accomplished with the knowledge that the permeability of soils decreases with an increasing silt and clay content. The sand [SP] and sand with silt [SP-SM]/[A-3] soil types can usually be dewatered by well pointing. Alternative means of dewatering may be necessary for the silty/clayey fine sands. Dewatering means and methods are the sole responsibility of the contractor. It should be noted that lowering the groundwater table usually results in an increase in the effective stresses on the bearing soils of the nearby utilities and structures and hence may cause unfavorable settlements of these utilities and structures. We recommend the project specifications call for monitoring existing utilities and structures for any potential settlement due to dewatering.

Dewatering will require the implementation of concurrent activities. The dewatering system should be installed with sufficient time prior to excavation activities to allow for adequate water drainage from soils. Dewatering discharge shall comply with water management regulations. Turbidity control measures may be implemented as necessary. The dewatering system should be flexible with respect to discharge capacities and take into account unexpected large rate flow. Because of the variability of layers of sand and soil permeability, appropriate factor of safety should be used in the design of the dewatering system.

4.5 TRENCH BEDDING AND BACKFILLING RECOMMENDATIONS

We recommend that all excavation, backfilling, and verification procedures conform to the most current Florida Department of Transportation Standard Specifications for Roadway and Bridge Construction.

The following recommendations should be followed while installing the proposed utility lines.

Where required, the soils in the areas of excavations for the installation of the proposed force main should be dewatered prior to the start of excavation. The groundwater level should be maintained at least 24 inches below the base of the trench and compaction surface during construction and backfill activities.

After proper dewatering, excavate the trench as per the design configuration. Excavated trenches should be set back to a stable configuration or shored, in either case in accordance with OSHA requirements. Adequate bracing should be provided if necessary to prevent side slope failures.

Compact the trench bottom to a minimum density of 95 percent of the Modified Proctor maximum dry density to a depth of 1-foot below the bottom of the pipe or place the pipe in gravel bedding as described by FDOT Design Standards. If limestone is encountered at invert elevations, it should be undercut at least 12 inches, the sides and bottom of the undercut lined with geo-textile filter fabric and backfilled with compacted sand comparable in composition to the native sands. The limestone excavation may require use of ripping teeth headache balls, etc., to facilitate removal. Remove rock, boulders or other hard lumpy or unyielding material to depth of 12 inches below the bottom of the pipe elevation.

The subgrade after excavation in some areas may include silty/clayey sands [SM/SC] [A- 2-4]/[A-2-6], which will be difficult to compact. If difficult compaction operations are encountered beneath the utilities due to excessive fines and/or wet conditions, a qualified representative of the owner’s testing agency should be consulted for recommendations. It may be an option to over-excavate and replace the saturated soils with FDOT No. 57 stone to stabilize the subgrade soils and obtain a stable workable platform. The undercut area should be covered with a geotextile (separation) fabric and then backfilled with compacted granular fill. Some areas may also include very clayey sands or sandy clay [SC/CH][A-6]/[A-7]; these soils should be over-excavated and removed under the direction of the testing agency representative.

Fill materials above the spring-line of the pipe should be compacted to a minimum of 95 percent of the Modified Proctor maximum dry density (AASHTO T-180/ASTM D-1557).

Native soils consisting of clean sands with less than 12 percent fines may be used as backfill material provided they are inorganic, have moisture contents below the optimum level and are properly placed.

If imported materials are used as trench backfill material, the imported fill should contain less than 5 percent soil fines passing a number 200 sieve. You may also use imported fill material containing 5 to 12 percent soil fines; however, strict moisture control measures will be required, particularly for placement of these materials in excavations extending below the groundwater level.

Backfill placed around the pipe and extending up to a level of 12 inches above the top of the pipe should be placed in loose, 6-inch lifts and compacted with light-weight equipment such as a small plate compactor. The remaining backfill may be placed in loose, 12-inch lifts across the full trench width and compacted. All backfill lifts should be compacted to a minimum density of 95 percent of the Modified Proctor maximum dry density prior to the placement of additional backfill. Compaction within the backfill trench should be performed using light-weight compaction equipment until the backfill has attained a level of at least 4 feet above the crown of the pipe.

Compliance test for densities should be performed as recommended by FDOT standards.

We recommend that existing structures in close proximity to the proposed improvements should be monitored for signs of distress during adjacent new excavation and structure construction operations. Vibrations produced during pipe installation (pipe bursting, etc.)

may cause distress to adjacent structures. Provisions should be made to monitor these vibrations so that any necessary modifications can be made before potential damages to adjacent structures.

4.6 SUITABILITY OF EXCAVATED SOILS

We understand that fill material resulting from the (open cut) trench excavation activities may be reused as backfill material. We believe the onsite soils resulting from excavations will vary significantly, in terms of their suitability for use as engineered backfill and fill.

Soil materials excavated and classified as fine sands to sand with silts and sand with clay [SP, SP-SM, SP-SC]/(A-3), with typically 12% fines or less (silt/clay fraction), may be considered suitable for use as utility trench backfill and pavement structural fill, provided said materials are properly dried, placed, and compacted.

Soil materials excavated and classified as silty to slightly clayey fine sands [SM, SC]/(A-2-4), with typically 12% to 25% fines, should be considered marginally suitable for use as utility trench backfill and structural fill, after significant drying and some mixing with the fine sand material described above. Proper placement, proof rolling and compaction must also be performed.

Soil materials excavated and classified as clayey sand silt or clay [SC, ML, MH, CL, and CH]/ (A- 2-6 to A-7) and any organic-laden soils (5% or greater organics by weight) should not be reused as fill. These materials could be used in green areas, if applicable and in non-structural applications where excessive ground subsidence will not create functional or aesthetic problems.

Soil borings for a typical geotechnical report are widely spaced and generally not sufficient for reliably detecting the presence of isolated, anomalous surface or subsurface conditions, or reliably estimating unsuitable or suitable material quantities. Accordingly, UES does not recommend relying on our boring information to negate presence of anomalous materials or for estimation of material quantities unless our contracted services specifically include sufficient exploration for such purpose(s) and within the report we so state that the level of exploration provided should be sufficient to detect such anomalous conditions or estimate such quantities.

Therefore, UES will not be responsible for any extrapolation or use of our data by others beyond the purpose(s) for which it is applicable or intended.

4.7 TRENCHLESS METHODS SOIL DESIGN PARAMETER RECOMMENDATIONS

The geotechnical information presented in Table 5 below is provided to aid the Horizontal Directional Drilling (HDD) construction, and design process in the area, and is a representation of the soil conditions encountered. It should be noted that the soil parameters presented in Table 5 are ultimate values and that appropriate factor of safety should be applied.

Table 5 – Soil Design Parameters Recommended¹ Depth Below

Site Grade (ft)

Soil Description

Saturated/ Submerged Unit Weight

(pcf)

Friction Angle

(degrees)

Shear Strength Cohesion

(psf)

Earth Pressure Coefficients

From To Active KA Passive KP

Soil Boring B-1

0 2.5 Loose silty Sand [SM]/[A-2-4] 105/42.6 29 0 0.35 2.88

2.5 4 Firm sandy Clay [CH]/[A-7-6] 105/42.6 0 500 1.00 1.00

4 252 LIMESTONE 125/62.6 0 >8,000 1.00 1.00

Soil Boring B-2

0 2.5 Medium dense silty Sand

[SM]/[A-2-4] 110/47.6 31 0 0.32 3.12

2.5 7 Very loose to loose silty-clayey Sand [SM-SC]/[A-2-4] 100/37.6 28 0 0.36 2.77

7 13.5 Loose to medium dense clayey Sand [SC]/[A-2-6] 105/42.6 30 0 0.33 3.00

13.5 202 Medium dense clayey Sand

[SC]/[A-2-6] 110/47.6 32 0 0.31 3.25

Soil Boring B-3

0 2.5 Medium dense to loose clayey Sand [SC]/[A-2-6] 105/42.6 30 0 0.33 3.00

2.5 14 Stiff to very stiff sandy Clay to Clay

[CH]/[A-7-6] 115/52.6 0 2,000 1.00 1.00

14 202 LIMESTONE 120/57.6 0 4,000 1.00 1.00

¹ It should be noted that the soil parameters presented above in Table 5 are ultimate values and that appropriate factor of safety should be applied.

² Indicates strata encountered at boring termination, total thickness undetermined.

³ It should be noted that the zero values represent marginal/residual values.

4.8 LIFT STATION FOUNDATION DESIGN RECOMMENDATIONS

Based on the project information provided, we understand that this project includes the construction of new lift station manhole structures. We assume the bottom of these structures will be located approximately 15 feet below existing grades.

We estimate that the manhole structure foundation, designed with an average net bearing pressure not exceeding 2,000 psf will provide satisfactory performance on this project. Removal of the overburden soils during the excavation process for precast concrete structure installation will result in the reduction of in-place soil stresses. We anticipate the foundation will be subjected to short term settlements of less than 1 inch.

We assume that some manhole structures and the pump station foundation structure will bear between depths of 5 to 15 feet within the limestone stratum. Hard lenses of limestone may be encountered that require greater than normal removal techniques. If limestone is found during the foundation excavations, we recommend that all excavation cut into the limestone deposit extend at least 2 feet below the required bottom elevation of the excavation.

The bottom of the lift station should be visually inspected by the Geotechnical Engineer. The Geotechnical Engineer should be contacted if dissimilar bearing soil conditions, such as clayey sand/soil-rock mix versus cemented limestone, are exposed beneath the bottom of the structure.

Removal of cemented limestone may be required if dissimilar bearing conditions are encountered within 2 feet of the proposed bottom of the structure.

Some ancillary structures will bear within or very near clayey soils. The subgrade after excavation in some areas may include clayey soils which will be difficult to compact. If these soils are soft in nature, they should be over-excavated and removed under the direction of the testing agency representative. Under certain circumstances the testing agency on site may determine that is may be necessary to import stone and gravel (FDOT #57 stone) to stabilize the subgrade soils and obtain a stable workable platform. The undercut area should be covered with a geotextile (separation) fabric and then backfilled with compacted granular fill. We also recommend that the lateral limits of over excavation extend at least 2 feet beyond the edges of the lift stations/manhole structures.

We recommend all foundations incorporate the seasonal high groundwater conditions. The lift station structure should be designed to overcome buoyancy forces exerted on the installed structure. The project requires the subgrade be dewatered to a minimum of 2 feet below the excavation bottom. Furthermore, the site should always be graded to prohibit ponding of stormwater runoff. Use of temporary dewatering measures may be needed to facilitate construction in the dry condition. The amount and method of the dewatering system should be determined by the contractor, and based upon their experience. The method of dewatering must be submitted by the contractor and approved by the design engineer.

We anticipate the structure will exert little or no net downward pressure on the soils; rather, the structure may be subject to hydrostatic uplift pressure when the structure is empty. Below grade structures should be designed to resist lateral earth pressures and hydrostatic uplift pressures appropriate for their depth below existing grade and wet season groundwater table.

The walls of the structure should be designed to resist at-rest lateral earth pressures, with equivalent fluid densities above and below the water table being as follows:

Above Water Table – Equivalent Fluid Density 55 pcf Below Water Table – Equivalent Fluid Density 90 pcf

The water table for wall design purposes should be assumed to be at 2 feet below the existing grade.

Foundation Preparation – Based on our evaluation of the soil conditions encountered in this area, we offer the following recommendations for the proposed underground construction:

The proposed construction area should be dewatered as necessary and excavated to the required foundation depth. Excavation work will be required to meet OSHA Excavation Standard Subpart P regulations. It should be anticipated that weakly cemented clayey soils and hard limestone which may be difficult to excavate will be encountered in the excavation process. The Geotechnical Engineer should be contacted if dissimilar bearing soil conditions, such as clayey sand versus cemented limestone, are exposed beneath the bottom of the structure. It should be anticipated that some removal of cemented limestone will be required if encountered within 2 feet of the proposed bottom of the structure.

The proposed construction area should be dewatered as necessary and excavated to the required foundation depth. Excavation work will be required to meet OSHA Excavation Standard Subpart P regulations.

Temporary dewatering may be required, particularly during deeper excavation. If required, water table should be maintained at least 2 feet below the proposed excavation bottom.

The dewatering system should not be decommissioned until sufficient deadweight exists on the structure to prevent uplift or the uplift protection system as described below, if necessary, is in place.

If compaction of the stones or gravel is to be performed by impact using the loader bucket, lifts should not exceed about 6 inches. For compaction using hand operated vibratory equipment, lifts should not exceed 12 inches.

Backfill which will be required around buried walls, should be compacted with a light hand-operated compactor to a density of 95 percent of the soils Modified Proctor maximum dry density. All backfill should be placed in level lifts not exceeding six inch loose lift thickness.

Care should be taken not to over compact the backfill (i.e., limit compaction to a maximum of 98 percent of the maximum density) in order to limit the lateral loads on the proposed walls.

Structural fill/backfill should consist of an inorganic non-plastic granular soil with less than

10 percent fines and a Unified soil classification of SP, SP-SM, SW or SW-SM (relatively clean sand).

Uplift Protection – When the water level within below-grade structures is maintained at or above the surrounding groundwater level, no net buoyancy will occur to the structure. However, when these structures are drained for maintenance or as water levels fluctuate within the structure, a positive means of uplift protection may be necessary. Hydrostatic uplift forces can be resisted in several ways including:

1. Addition of dead weight to the structure.

2. Mobilizing the dead weight of the soil surrounding the structure through extension of footings outside the perimeter of the structure.

3. Use of a permanent gravity or mechanical dewatering system that is operated only when the structure is to be drained.

4. Use of pressure relief valves in the slab bottom in combination with one or more of the above methods, or

5. Use of uplift piles.

We anticipate that one or more of the noted methods will be needed for this construction. At your request, we would be pleased to assist you in evaluating uplift protection requirements.

5.0 REPORT LIMITATIONS

This Report has been prepared for the exclusive use of Ardurra, and…