GEOTECHNICAL

ENGINEERING

REPORT

Brickyard Road Drainage Improvements Molino, Escambia County, Florida

PREPARED FOR:

Sigma Consulting Group, LLC 3298 Summit Boulevard, Suite 32

Pensacola, Florida 32503

NOVA Project Number: 10116-2023153

October 5, 2023

P R O F E S S I O N A L | P R A C T I C A L | P R O V E N

1 4 0 - A L u r t o n S t r e e t , P e n s a c o l a , F l o r i d a 3 2 5 0 5 t . 8 5 0 . 6 0 7 . 7 7 8 2 / f . 8 5 0 . 2 4 9 . 6 6 8 3 / u s a n o v a . c o m

October 5, 2023

Sigma Consulting Group, LLC

3298 Summit Boulevard, Suite 32

Pensacola, Florida 32503

Attention: Mr. Jason L. Lashley, P.E.

Subject: Geotechnical Engineering Report

BRICKYARD ROAD DRAINAGE IMPROVEMENTS

NOVA Project Number 10116-2023153

Dear Mr. Lashley:

NOVA Engineering and Environmental, LLC (NOVA) has completed the authorized Geotechnical

Engineering Report for the proposed infrastructure improvements planned for Brickyard Road in the Molino area of Escambia County, Florida. The work was performed in general accordance with NOVA Proposal Number 10116-2023153, dated June 9, 2023. This report briefly discusses our understanding of the project at the time of the subsurface exploration, describes the geotechnical consulting services provided by NOVA, and presents our findings, conclusions, and recommendations.

We appreciate your selection of NOVA and the opportunity to be of service on this project. If you have any questions, or if we may be of further assistance, please do not hesitate to contact us.

Sincerely, NOVA Engineering and Environmental LLC

Jesse A. James, P.E. William L. Lawrence, P.E.

Project Engineer Principal Engineer

Florida Registration No. 90470 Florida Registration No. 60147

Copies Submitted: Addressee (electronic)

TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 NAME AND LOCATION OF PROJECT

1.2 AUTHORIZATION AND SCOPE OF STUDY

2.0 PROJECT INFORMATION

2.1 PROJECT SITE

2.2 PROPOSED DEVELOPMENT

3.0 SUBSURFACE EXPLORATION

3.1 AREA GEOLOGY

3.2 FIELD EXPLORATION

3.3 LABORATORY TESTING

3.4 SUBSURFACE CONDITIONS

4.0 GEOTECHNICAL ASSESSMENT

5.0 RECOMMENDATIONS

5.1 DAM RESTORATION

5.2 SITE PREPARATION

5.3 EXCAVATION

5.4 FILL PLACEMENT

5.5 RETAINING WALLS

6.0 LIMITATIONS

APPENDICES

Appendix A – Figures and Maps

Appendix B – Subsurface Data

Appendix C – Laboratory Test Data

Geotechnical Engineering Report October 5, 2023

Brickyard Road Drainage Improvements NOVA Project Number 10116-2023153

1.0 INTRODUCTION

This section provides information relating to our contract, the purpose of our work, and a summary of our understanding of the project,

1.1 NAME AND LOCATION OF PROJECT

The study area is located along Brickyard Road south of its intersection with Barth

Road in Molino, Escambia County, Florida. The location of the roadway alignment of study is indicated on the Site Location Map included in Appendix A.

1.2 AUTHORIZATION AND SCOPE OF STUDY

Our work on this project was as described in our Proposal Number 10116-2023153, dated June 9, 2023. The primary objectives of this work were to perform a geotechnical exploration within the areas of the proposed improvements and to assess these findings as they relate to geotechnical aspects of the planned site development. The authorized geotechnical engineering services included site reconnaissance, soil test borings and sampling, engineering evaluation of the field and laboratory data, and the preparation of this report. Our written report includes the following:

➢ A description of the site, fieldwork, laboratory testing and general soil conditions encountered, as well as a Boring Location Plan and individual Test Boring

Records.

➢ Site preparation considerations that include geotechnical discussions regarding site stripping and subgrade preparation, and engineered fill/backfill placement.

➢ Recommendations for controlling groundwater and/or run-off during construction.

➢ Suitability of on-site soils for re-use as structural fill and backfill. Additionally, the criteria for suitable fill materials are provided.

➢ Measured apparent groundwater and estimated normal permanent seasonal high groundwater (SHGW) levels.

➢ Slope stability analysis of the proposed cross section.

➢ Sheet-pile wall design parameters.

➢ Recommended quality control measures (i.e., sampling, testing, and inspection requirements) for construction.

The assessment of the presence of wetlands, floodplains, or water classified as state waters was beyond the scope of this exploration. Additionally, the assessment of site environmental conditions, including the detection of pollutants in the soil, rock, or groundwater, at the site was also beyond the scope of this geotechnical exploration and evaluation.

2.0 PROJECT INFORMATION

Our understanding of this project is based on discussions with the Client and the Design Team, review of the provided site plans, a site reconnaissance during boring layout, and our experience with similar projects in the Florida Panhandle.

2.1 PROJECT SITE

At the time of our field exploration, the alignment of study consisted of an asphalt paved roadway along the crest of an earthen dam. The dam was vegetated with dense undergrowth and mature trees. A railroad traversed the eastern heel of the earthen dam, and a pond was located on the western side of the dam.

2.2 PROPOSED DEVELOPMENT

NOVA understands the project will include the restoration and realignment of an existing dam structure (which also encompasses a segment of the Brickyard Road alignment), installation of a new discharge system, and the design of a sheetpile wall along the leeward side of the dam structure (to avoid encroachment into a DSX railway easement).

3.0 SUBSURFACE EXPLORATION

3.1 AREA GEOLOGY

The site is located in the Escambia County, Florida area and according to the United

States Geological Survey (USGS), is situated within the greater Gulf Coastal Plain region.

The site is generally covered with Alluvium sediments of the Pleistocene/Holocene periods underlain by the Citronelle formation of the Pliocene/Pleistocene periods. The alluvial sediments typically consist of siliciclastics that are fine to coarse quartz sand containing clay lenses and gravel in places. Sands consists primarily of very fine to very coarse poorly sorted quartz grains; gravel is composed of quartz, quartzite, and chert pebbles. In areas of the Valley and Ridge province gravels are generally composed of angular to sub-rounded chert, quartz, and quartzite pebbles. Coastal deposits in the

Escambia County area include fine to medium quartz sand with shell fragments and accessory heavy minerals along Gulf beaches and fine to medium quartz sand, silt, clay, peat, mud and ooze in the Mississippi Sound, Little Lagoon, bays, lakes, streams, and estuaries. The Citronelle formation consists primarily of varicolored/mottled lenticular beds of poorly sorted sand, clayey sand, clay, and clayey gravel. Limonite pebbles and lenses of limonite cemented sand occur locally in weathered Miocene exposures.

Surficial soils in the region are primarily siliciclastic sediments deposited in response to the renewed uplift and erosion in the Appalachian highlands to the north and sea-level fluctuations. The extent and type of deposit is influenced by numerous factors, including mineral composition of the parent rock and meteorological events.

3.2 FIELD EXPLORATION

Our field exploration was conducted on August 10, 2023, and included performing:

• Four 75-foot deep SPT borings (designated as B-1 through B-4) down the centerline of the existing dam/roadway alignment.

• Three auger borings (R-1, R-2, and R-3) along the side slopes of the alignment.

The boring locations were established in the field by NOVA personnel using a handheld

GPS device and estimating distances and angles from site landmarks. Prior to initiating field testing, underground utilities were marked by Sunshine811. Any required underground utility related adjustments of the test locations were then made at the time of the field exploration. The approximate test locations are shown on the Boring Location

Plan provided in Appendix B. If increased accuracy is desired by the client, test locations and elevations may be surveyed.

The Test Boring Records in Appendix B show the Standard Penetration Test (SPT) resistances, or “N-values”, and present the soil conditions encountered in the borings.

These records represent our interpretation of the subsurface conditions based on the field exploration data, visual examination of the split-barrel samples, laboratory test data, and generally accepted geotechnical engineering practices. The stratification lines and depth designations represent approximate boundaries between various subsurface strata. Actual transitions between materials may be gradual.

The groundwater levels reported on the Test Boring Records represent measurements made at the completion of each test boring, following a suitable stabilization period. The test borings were subsequently backfilled with soil cuttings from the drilling process for safety concerns.

SPT Borings

The test borings were performed using the guidelines of ASTM Designation D-1586, "Penetration Test and Split-Barrel Sampling of Soils". A mud rotary drilling process was used to advance these borings once groundwater was encountered. At regular intervals, soil samples were obtained with a standard 1.4-inch I.D., 2.0-inch O.D., split-tube sampler. The sampler was first seated six inches and then driven an additional foot with blows of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot is designated the "Penetration

Resistance". Representative portions of the soil samples, obtained from the sampler, were placed in sealed containers and transported to our laboratory for further evaluation and laboratory testing.

Hand Auger Borings

The auger borings were performed using the guidelines of ASTM Designation D-1452, "Soil Exploration and Sampling by Auger Borings". A manually advanced 3¼-inch diameter orchard-type auger was utilized with disturbed samples acquired continuously for the full depth of the boring. Representative portions of the soil samples, obtained from the sampler, were placed in sealed containers and transported to our laboratory for further evaluation and laboratory testing.

3.3 LABORATORY TESTING

Following completion of the field work, soil samples obtained in the field were returned to our office for classification and laboratory testing assignment.

These tests included the following:

• Manual/Visual Soil Classification

• Moisture Content

• Fines Content (minus the #200 sieve)

• Organic Content

• Atterberg Limits

The purpose of the testing program was to classify the subsurface materials relative to the Unified Soil Classification System (USCS) and to determine their physical characteristics including strength, and compressibility. Detailed descriptions of the tests conducted are presented in Appendix C.

The soil samples will be discarded 30 days following the submittal of this report, unless you request otherwise.

3.4 SUBSURFACE CONDITIONS

The following paragraph provides a generalized description of the subsurface profiles and soil conditions encountered in the borings conducted during this study. The Test

Boring Records in the Appendix should be reviewed to provide detailed descriptions of the conditions encountered at each boring location. Conditions may vary at other locations and times.

Within the existing roadway alignment, the deeper test borings generally encountered an asphalt pavement section consisting of approximately 2- to 2½-inches of asphalt underlain by 9- to 24- inches of a medium dense to very dense fine-grained silty sand base course (USCS classification of SM), in turn underlain by mixed strata of fine-grained silty to clayey sands (SM, SM/SC, SC) with intermixed brick fragments to 12 feet to 20 feet below existing grade (BEG) which roughly correlated to the pre-existing ground surface. From this depth the test borings encountered loose to very loose, organic-laden fine-grained silty to clayey sands (SM, SM/SC) which extended to about 22 feet BEG underlain by medium dense to very loose fine-grained slightly silty sands (SP-SM) to about 45 feet BEG, where the test borings encountered a stratum of stiff to hard low-plasticity clay (CL) with interbedded iron rock to roughly 65 feet BEG, therein underlain by medium dense fine-grained sands (SP) to the maximum depth explored of approximately 75 feet BEG.

The auger borings conducted along the side slopes of the dam structure encountered a thin stratum of topsoil underlain by fine-grained silty to clayey sands (SM, SC) with intermixed brick fragments to the maximum depths explored of roughly 4 feet to 8 feet

BEG, where the borings met auger refusal due to the aforementioned debris.

Groundwater Conditions

Groundwater in the Gulf Coastal Plain typically occurs as an unconfined aquifer condition. Recharge is provided by the infiltration of rainfall and surface water through the soil overburden. More permeable zones in the soil matrix can affect groundwater conditions. The groundwater table is expected to be a subdued replica of the original surface topography. Based on a review of topographic maps and our visual site observations, we anticipate the groundwater flow at the site to be towards the south.

Groundwater levels vary with changes in season and rainfall, construction activity, surface water runoff and other site-specific factors. Groundwater levels in the Escambia

County area are typically lowest in the late fall to winter and highest in the early spring to mid-summer with annual groundwater fluctuations by seasonal rainfall; consequently, the water table may vary at times.

A stabilized groundwater table was encountered in the test borings at depths ranging between about 13 feet to about 19½ feet BEG during of our field exploration, which occurred during a period of relatively normal seasonal rainfall.

Based on comparisons of current annual monthly rainfall data to historical rainfall data extending back 50+ years in time, we estimate that the normal permanent seasonal high groundwater (SHGW) table for this site will occur within about 1 foot above the measured groundwater depths at each boring location, during the wet season. We note that flood events forcing the adjacent pond to stage up will heavily influence temporary groundwater levels along the western side of the basin.

4.0 GEOTECHNICAL ASSESSMENT

The following assessment is based on our understanding of the proposed construction, our site observations, our evaluation and interpretation of the field data obtained during this exploration, our experience with similar subsurface conditions, and generally accepted geotechnical engineering principles and practices.

Based on the boring results, following site stripping and grubbing of the proposed construction areas to remove all surficial vegetation and any other deleterious non-soil materials that are found to be present, the proposed construction appears to be feasible employing conventional site preparation practices as recommended in the Site Preparation section of this report.

We note that subsurface conditions in unexplored locations may be different from those encountered at the test locations considered and discussed herein. If such variations are noted during construction, or if project development plans are changed, we request the opportunity to review the changes and amend our recommendations, if necessary.

The following sections present our recommendations for site preparation and grading, and for the design of foundations and below-grade walls.

5.0 RECOMMENDATIONS

5.1 DAM RESTORATION

Based on our conversations with the Client, seepage through the dam has likely occurred in the past. In addition, we understand that the dam is architectural, and that some seepage is anticipated in the new area of the dam. Without improvement of the existing soil both beneath and through the dam some seepage should be expected.

Seepage itself is not uncommon and is anticipated in a homogenous earth dam;

however, it must be controlled. We note that uncontrolled seepage is undesirable through an earthen dam since migration of fines and ultimately piping may result with time.

We recommend that a clay core be installed in the remediated section of the dam. The top of the core should coincide with the top of the dam. The interior slope should be

2H:1V, and the exterior slope should be 1H:1V. A soil keyway trench should be extended to a minimum depth of 6 feet into residual materials along the contact between the existing soil and the new dam section. The bottom of the keyway should be 8 feet wide, and the sides should slope up to the bottom of the dam at 1H:1V. It is our understanding that Sigma is planning to include a clay core with the aforementioned requirements.

In order to control groundwater flow through the dam, NOVA recommends adding square blocks around the outflow pipe. The blocks should be of a dimension greater than the diameter of the outflow pipe. The purpose of the blocks is to slow water velocity and stop sediment from traveling along the perimeter of the pipe, thereby reducing the potential for piping. It is our understanding that Sigma is planning to include blocks along the outflow pipe. In order to control groundwater leakage through the front face of the dam which may carry soil with it, NOVA recommends employing a chimney drain set back approximately 20 feet from the toe of the dam. The drain should be parallel to the dam alignment and cross the full length of the dam. The drain should be perforated PVC or RCP pipe surrounded by a geosynthetic filter fabric and should have drain pipes perpendicular to it exiting out the front of the dam into a toe drain. It is our understanding that Sigma is planning to include such a system.

Dam Slope Stability

The results of the geotechnical exploration were used to perform a slope stability analysis on the upstream and downstream slopes using Slide2 from Rocscience, Inc.

In evaluating the downstream slope for steady state seepage conditions, an effective stress analysis was used in conjunction with the Bishop Simplified Method of slices for circular arc failures. For the rapid draw-down analysis of the upstream slope, the

Bishop Simplified Method was again used in the total stress mode. Our analysis has considered the slope configurations provided by Sigma. The dimensions are summarized in the following schematic.

Soil parameters and assumed water tables are shown on the results presented in

Appendix D. These inputs result in a factor of safety of 1.32 or greater for both the upstream and downstream slopes. The results for the minimum factors of safety obtained from the analysis are shown in Appendix D. We believe that safety factors of

1.1 (earthquake) and 1.5 (steady state seepage) are appropriate for the downstream section of a dam and that a safety factor of 1.3 is appropriate for rapid draw-down condition of the upstream section.

Based on our experience with previous construction, and the results of the stability analysis, we believe that the proposed dam section should achieve these desired factors of safety. New fill soils should meet the requirements for both quality/composition and compaction as recommended in the subsequent sections of this report. Additionally, a NOVA representative should be on-site during construction to document that contract documents and generally accepted construction practices are followed.

Settlement

Laboratory analysis to determine soil settlement parameters was beyond the scope of this study. However, based on approximate correlations between penetration resistances and elastic modulus values, it appears that settlement of the dam crest should be minimal (i.e., less than 1 inch).

We note that more total settlement could occur, however, the majority will take place during construction. Initial settlements are typically 60 to 90 percent of the total settlement in typical naturally occurring soils. The remaining consolidation generally takes place in a period of 3 to 6 months after load application. The estimates of settlement have been based on our previous experience with similar construction.

5.2 SITE PREPARATION

We understand that the desired finish site grade elevations will closely match the existing roadway and dam alignment.

Prior to proceeding with construction operations, the entire dam footprint should be stripped of surface and near surface debris. It is recommended that clearing and stripping operations extend beyond the downstream toe of the new dam section, if allowed by appropriate wetlands and/or land disturbance permits. This operation should consist of complete removal and wasting of trees, topsoil, root systems, loose sediment deposits, and other non-soil materials.

Beneath the new dam footprint, the initial stripping operations must be sufficient to remove all deleterious materials, including topsoil and deposited sediments resulting from past flood events, which may adversely affect the stability and seepage potential of the new dam section. Additional undercutting of water-softened soils may also be required in some areas.

We believe close coordination of the site and subgrade preparation by the geotechnical engineer is one of the most critical aspects of the proposed construction. The engineer will need to make field decisions as problems arise in specific areas concerning undercutting, groundwater control, subgrade stabilization and other remedial techniques. All subgrade areas should be approved by the geotechnical engineer prior to fill placement.

5.3 EXCAVATION

Excavation bracing (shoring) design and installation is typically the responsibility of a specialty contractor working for the general contractor. Permanent installations will require design review and comment by the Structural Engineer and the Geotechnical

Engineer of Record. Excavations greater than five feet deep (assumed to be applicable for the abutment foundation installations) should be sloped or shored in accordance with local, state, and federal regulations, including OSHA (29CFR Part 1926) excavation safety standards. It should be noted that the Contractor is solely responsible for site safety.

This information is provided only as a service and under no circumstances should NOVA be assumed to be responsible for construction site safety. Each excavation should be observed and classified by an OSHA-competent person. All excavations below the groundwater level are classified as OSHA Class C soils for excavation purposes.

Since successful excavation bracing system construction is partially dependent on the technique and experience of the contractor, we believe the system should only be installed by a contractor with a minimum of 5 years of experience in tieback wall, soil nailing or other specialty bracing system installation. Design flexibility should be allowed for the specialty contractor to choose the most appropriate bracing system, including the method of forming the anchor and the required embedment length.

Groundwater Control

A stabilized groundwater table was encountered in the test borings at depths ranging between about 13 feet to 19½ feet BEG at the time of our field exploration, which occurred during a period of relatively normal seasonal rainfall.

Depending on the time of construction conditions, problems with the control of ground water and surface water could potentially be an issue at this site during initial site and dam foundation preparation, and initial fill placement. All surface flows from the drainage basin above the dam site should be routed around the immediate construction area(s). We caution that the diversion of surface flows is considered a critical operation in dam construction; consequently, the diversion method and time schedule are very important design and construction elements.

Dewatering will therefore most likely be required to perform the required construction.

The dewatering system should be capable of lowering the groundwater table to a minimum of 3 feet below the desired working platform, in order to maintain reasonable stability and workability of exposed subgrade soils. The drainage paths that currently convey stormwater through the existing drainage structure should be temporarily re-routed.

A contractor familiar with similar site conditions common to the Escambia County area and re-routing or temporary damming of creek/drainage systems should be able to determine an adequate dewatering method for the drainage improvement project.

Common local dewatering methods include but are not limited to coffer dams, sheet pile walls, sump pits, and dewatering by the use of temporary well points and trench drain systems. Design flexibility should be allowed for the specialty contractor to choose the most appropriate dewatering system, including the well depths and spacing.

It is our opinion that the most suitable approach for dealing with groundwater problems may best be achieved during construction with on-the-spot field recommendations. If the ground water is not properly controlled, a "quick" condition may result in an unstable subgrade and pockets of unsuitable material being trapped beneath the dam.

We again emphasize the need for close geotechnical engineering observation during the initial construction phases.

As previously noted, groundwater levels are subject to seasonal, climatic, and other variations and may be different at other times and locations. The extent and nature of any dewatering required during construction will be dependent on the actual groundwater conditions prevalent at the time of construction and the effectiveness of construction drainage to prevent run-off into open excavations.

5.4 FILL PLACEMENT

Fill materials for the shell of the new berm section should be a well- or poorly-graded sand (USCS classification of SW or SP), free of non-soil materials and rock fragments larger than 3 inches in diameter, and less than 3% fibrous organic materials by weight.

The clay core material should consist of a low plasticity clay (USCS classification of CL), with a minimum 70% fines, PI less than 30, total unit weight of at least 115 pcf, and having an in-situ permeability of 1x10-6 cm/sec or slower.

We recommend that dam fill and clay core materials be limited to soils with a Standard

Proctor maximum dry density of 95 pcf or higher. Continuous monitoring by a qualified engineering technician will be required during construction to assure the proper selection of suitable borrow materials.

Prior to fill placement against existing slopes, loose surficial materials should be removed and the slope should be benched or stepped to provide horizontal benches for compaction, and to reduce the possible movement of soil along the slope interface.

After completion of subgrade preparation as described above, structural fill can be placed to bring the site to final grade.

Structural fill should be placed in layers not exceeding 8 inches in thickness when loose and should be compacted to a minimum soil density of at least 95 percent of the

Standard Proctor maximum dry density (ASTM D-698). Where portable hand equipment is required, maximum lift thickness should be 4 inches loose measure.

Soil moisture content should be maintained within –2 to +3 percent of the optimum moisture content. Scarification and benching of fill materials could be required to adequately bond the fill materials to the existing soils.

We recommend that the grading contractor have equipment on site during earthwork for both drying and wetting fill soils. We do not anticipate significant problems in controlling moistures within the fill during dry weather. During winter months or extended periods of rain, moisture control problems will most likely occur. We suggest that the contractor be required to initially adjust moisture contents (if necessary) at the approved off-site borrow source prior to transporting fill to the dam site. However, we again note that tight control of the fill placement is considered critical. Substantial rains prior to or during construction may require additional remedial efforts to stabilize the working subgrade. The residual and fill soils are susceptible to degradation when wet; therefore, moisture control will be an important aspect of fill placement.

Any placed fill that becomes excessively wet or dry should be immediately corrected.

Any unsuitable or damaged fill (rain, siltation, freeze, thaw, etc.) should not be covered with additional fill. Construction procedures and equipment should be selected to assure that the surface of each fill lift is left in a non-smooth condition to provide adequate bonding with subsequent fill lifts. All fill lifts should be graded to prevent surface water ponding. The surface of all fill should be sealed at the end of each work day with proofrolling by rubber tired rollers.

Filling operations should be observed by a NOVA soils technician, who can confirm suitability of material used and uniformity and appropriateness of compaction efforts.

The technician can also document compliance with the specifications by performing field density tests using thin-walled tube, nuclear, or sand cone testing methods (ASTM

D-2937, D-6938, or D-1556, respectively).

Erosion Control

After final grading of the slopes and crest, suitable erosion protection should be provided as recommended by Sigma Consulting Group, Inc. Low maintenance grasses are employed most commonly on the downstream slope, crest, and exposed freeboard of the upstream slope. We recommend that the crest be sloped slightly toward the reservoir to prevent surface runoff from flowing onto the face of the downstream slope, and that the area of the upstream slope susceptible to wave action be protected to prevent erosion and beaching.

Shoreline riprap protection is typically based on estimated wave heights for a particular wind speed and direction. Calculation of wave exposure and riprap protection is normally performed during final design by the civil engineer after maximum pool and design storm criteria are established. For preliminary budget estimating purposes, we recommend that the riprap extend from the top of the embankment to at least 3 feet below the normal pool level.

Riprap should consist of 36 inches (measured perpendicular to the slope) of reasonably well-graded rock fragments with a maximum particle size of 24 inches and a predominance of rock fragments in the 12-inch size range. The individual riprap rock fragments should be dense, sound, and resistant to abrasion and should be free from cracks, seams, and other defects that would tend to unduly increase their destruction by water action.

The riprap and bedding for the upstream dam slope should be keyed into the slope such that the surface of the completed riprap approximately coincides with that of the general dam slope surface. Bedding for the riprap should consist of a layer of suitable geotextile (filter fabric) overlain by approximately 6 to 12 inches of bedding stone or sand to prevent punching of the fabric when the riprap is placed.

The riprap need not be compacted but should be placed to grade in a manner to ensure that the larger rock fragments are uniformly distributed and the smaller rock fragments serve to fill the spaces between the larger rock fragments in such a manner as will result in well-keyed, densely placed, uniform layers of riprap of the specified thickness.

Hand placing would be required only to the extent necessary to secure the results specified above, and adjacent to structures. The contractor's placement techniques should be subject to the approval of the engineer.

We also recommend that the abutment/dam contact be graded to prevent surface water flows, and subsequent erosion, along the interface. All surface water should be directed to flow along the residual soil face of the abutments. Consideration should be given to the need for possible positive protection in these areas.

Similarly, riprap protection will be required in the plunge pool of the principal spillway conduit and may also be necessary in the emergency spillway. The actual extent of armoring will be dependent of flow velocities.

5.5 RETAINING WALLS

The magnitude and distribution of earth pressures against below grade walls depends on the deformation condition (rotation) of the wall, soil properties and water conditions.

When the soil behind the wall is prevented from lateral strain, the resulting force is known as the at-rest earth pressure (KO). If the retaining structure moves away from the soil mass, the earth pressure decreases with the increasing lateral expansion until a minimum pressure, known as the active earth pressure (KA), is reached. If the wall is forced into the soil mass, the earth pressure increases until a maximum pressure, known as the passive earth pressure (KP), is obtained.

Free-standing retaining walls are usually designed for active earth pressures. However, the earth pressures must be compatible with the wall rotation, which is limited by the wall rigidity, foundation support conditions and connections to adjoining structures. If active earth pressure development requires horizontal wall movements that cannot occur, or which are architecturally undesirable, walls should be designed for an intermediate pressure based on restraint conditions.

Laboratory analysis to determine actual soil shear strength properties was beyond the authorized scope of the services. With the bearing level subgrade soils prepared as recommended in this report and as required by applicable local and/or FDOT indices, based on our experience with similar soils and construction, we recommend that the information provided in Table 1 below be considered when designing the proposed sheet pile wall system.

EXISTING SOIL DESIGN PARAMETERS

Approximate

Depth (feet)

BEG*

Average

SPT

‘N’ Value

Friction

Angle

(degrees)

Cohesion

(psf)

Total

(Effective)

Unit Weight

(pcf)

Lateral Earth Pressure

Coefficients

From To At Rest

(Ko)

Active

(Ka)

Passive

(Kp)

0 10 20 33 0

(115)

0.29 3.39 0.46

10 20 2 28 0

(120)

0.36 2.77 0.53

20 35 6 29 0

(50)

0.35 2.88 0.52

35 40 18 32 0

(45)

0.31 3.25 0.47

40 60 22 25 2,500

(55)

1.00 1.00 1.00

60 65 76 40 0

(55)

0.22 4.60 0.36

65 75 30 36 0

(45)

0.26 3.85 0.41

* BEG – Below Existing Grade.

Backfill Soil Design Parameters

With the backfill soil materials selected and prepared as recommended in the geotechnical report noted above, and as required by applicable FDOT indices, the following ultimate soil parameters below may be used in the proposed design:

• Backfill soil internal angle of friction = 30º

• Ko (Coefficient of earth pressure at rest) = 0.50

• Ka (Coefficient of active earth pressure) = 0.33

• Kp (Coefficient of passive earth pressure) = 3.00

• Unit weight of soil (Wet) = 120 pounds per cubic foot

• Unit weight of soil (Submerged) = 60 pounds per cubic foot

An appropriate factor of safety should be applied to these parameters (note that hydrostatic pressure forces should also be included in the proposed design).

Our lateral earth pressure recommendations assume that:

• The ground surface adjacent to the wall is level,

• Soils similar to those analyzed during this study will be reused for wall backfill,

• Heavy construction equipment does not operate within 5 feet of the wall,

• A constantly functioning drainage system is installed between the wall and the soil backfill, and

• Any footings or other significant surcharge loads are located outside the wall a distance at least equal to the wall height.

6.0 LIMITATIONS

The findings, conclusions and recommendations presented in this report represent our professional opinions concerning subsurface conditions at the site. The opinions presented are relative to the dates of our site work and should not be relied on to represent conditions at significantly later dates or at locations not explored. The opinions included herein are based on information provided to us, the data obtained at specific locations during the study and our experience. If additional information becomes available that might impact our geotechnical opinions, it will be necessary for NOVA to review the information, reassess the potential concerns, and re-evaluate our conclusions and recommendations.

Regardless of the thoroughness of a geotechnical exploration, there is the possibility that conditions between test locations will differ from those encountered at specific test locations, that conditions are not as anticipated by the designers and/or the contractors, or that either natural events or the construction process have altered the subsurface conditions. These variations are an inherent risk associated with subsurface conditions in this region and the approximate methods used to obtain the data. These variations may not be apparent until construction.

This report is intended for the sole use of Sigma Consulting, Inc. for the above noted project.

The scope of work performed during this study may not satisfy other user’s requirements. Use of this report or the findings, conclusions or recommendations by others will be at the sole risk of the user. NOVA is not responsible or liable for the interpretation by others of the data in this report, nor their conclusions, recommendations or opinions.

Our professional services have been performed, our findings obtained, our conclusions derived and our recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices in the State of Florida. This warranty is in lieu of all other statements or warranties, either expressed or implied.

APPENDIX A

Figures and Maps

Scale: Not To Scale PROJECT LOCATION MAP Date Drawn: July 31, 2023 Brickyard Road Drainage Improvements

Drawn By: N. Turan Molino, Escambia County, Florida Checked By: W. Lawrence NOVA Project Number 10116-2023153

140-A Lurton Street Pensacola, Florida 32505

850.607.7782 ♦ 850.249.6683

APPROXIMATE SITE LOCATION

APPENDIX B

Subsurface Data

Scale: Not To Scale BORING LOCATION PLAN Date Drawn: July 31, 2023 Brickyard Road Drainage Improvements

Drawn By: B. Blevins Molino, Escambia County, Florida Checked By: J. James NOVA Project Number 10116-2023153

140-A Lurton Street Pensacola, Florida 32505

850.607.7782 ♦ 850.249.6683

LEGEND

B-x = 75-ft. Structural SPT Boring R-x = 15-ft. SMS Auger Boring

B-2

B-1

B-3

B-4

R-2

R-1

R-3

KEY TO BORING LOGS

Medium Stiff

FI

N E -G R A

IN

E D S O

IL

S or m or e pa ss es th e N o.

si ev e*

C O A R S E -G R A

IN

E D S O

IL

S

M or e th an re ta in ed on th e th e N o.

si ev e*

ASPHALT (Approx. 2.5 inches) Orange/gray very dense fine-grained silty SAND (SM)

Light brown medium dense fine-grained silty SAND with trace of brick (SM)

Brown medium dense to dense fine-grained clayey SAND

(SC)

Gray loose fine-grained clayey SAND (SC)

Gray very soft to medium stiff low-plasticity CLAY (CL)

Orange loose fine-grained silty SAND (SM)

Orange medium dense fine-grained slightly silty SAND

(SP-SM)

Off-white/orange medium dense fine-grained SAND (SP)

Orange medium dense fine-grained slightly silty SAND

(SP-SM)

Gray very stiff to hard low-plasticity CLAY (CL)

Gray/orange dense fine-grained clayey SAND (SC)

Orange dense fine-grained silty/clayey SAND with iron rock (SM/SC)

Gray/orange medium dense fine-grained SAND (SP)

Boring Terminated at 75 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

B-1

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: American Drilling Inc. LOGGED BY: E. Sharpe

DRILLING METHOD: SPT Boring DATE: August 30, 2023 DEPTH TO - WATER> INITIAL: 13.5 ft. AFTER 24 HOURS: CAVING>

Trapped water from 13.5 ft. to 16.5 ft.

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

ASPHALT (Approx. 2.5 inches) Orange/light brown medium dense fine-grained silty

SAND (SM)

Gray medium dense fine-grained silty/clayey SAND

(SM/SC)

Orange/light brown medium dense fine-grained silty/ clayey SAND (SM/SC) Brown very stiff low-plasticity CLAY with layer of asphalt

(CL)

Orange medium dense fine-grained silty/ clayey SAND

(SM/SC)

Gray very loose fine-grained clayey SAND (SC)

Off-white/orange medium dense to very loose fine-grained slightly silty SAND (SP-SM)

Gray/orange medium dense fine-grained slightly silty

SAND (SP-SM)

Orange medium dense fine-grained slightly silty SAND with fine gravel (SP-SM)

Gray stiff low-plasticity CLAY with iron rock (CL)

Gray very stiff to hard low-plasticity CLAY (CL)

Off-white/orange medium dense to dense fine-grained slightly silty SAND (SP-SM)

Boring Terminated at 75 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

B-2

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: American Drilling Inc. LOGGED BY: E. Sharpe

DRILLING METHOD: SPT Boring DATE: August 29, 2023 DEPTH TO - WATER> INITIAL: 19 ft. AFTER 24 HOURS: CAVING>

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

ASPHALT (Approx. 2 inches) Orange dense fine-grained silty SAND with gravel (SM)

Orange/gray dense fine-grained silty SAND (SM) Gray/light brown medium dense fine-grained silty/clayey

SAND (SM/SC)

Light brown medium dense fine-grained silty SAND (SM)

Gray very loose fine-grained clayey SAND (SC)

Gray very loose fine-grained silty SAND (SM)

Gray/brown medium dense fine-grained slightly silty SAND with organics (SP-SM)

Brown loose fine-grained silty SAND with organics (SM)

Gray loose to medium dense fine-grained SAND with fine gravel (SP)

Brown loose fine-grained clayey SAND with organics (SC)

Brown/gray very stiff low-plasticity CLAY (CL)

Gray very stiff to hard low-plasticity CLAY (CL)

Orange very dense fine-grained silty SAND with iron rock

(SM)

Off-white medium dense fine-grained SAND (SP)

Off-white/orange medium dense fine-grained SAND (SP)

Boring Terminated at 75 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

B-3

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: American Drilling Inc. LOGGED BY: E. Sharpe

DRILLING METHOD: SPT Boring DATE: August 24, 2023 DEPTH TO - WATER> INITIAL: 19 ft. AFTER 24 HOURS: CAVING>

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

ASPHALT (Approx. 2.5 inches) Brown dense to medium dense fine-grained silty SAND

(SM)

Orange/brown medium dense fine-grained silty SAND

(SM)

Brown loose to medium dense fine-grained silty/clayey

SAND (SM/SC)

Brown medium dense fine-grained silty SAND with trace of brick (SM) Gray/brown very loose fine-grained silty/clayey SAND

(SM/SC)

Gray loose fine-grained silty SAND (SM)

Light brown medium dense fine-grained slightly silty SAND

(SP-SM)

Off-white/orange medium dense fine-grained slightly silty

SAND (SP-SM)

Orange medium dense fine-grained silty SAND with fine gravel (SM)

Brown medium dense fine-grained SAND (SP)

Orange/gray hard low-plasticity CLAY with iron rock (CL)

Gray stiff to very stiff low-plasticity CLAY (CL)

Orange very dense fine-grained silty/clayey SAND with iron rock (SM/SC)

Off-white dense to medium dense fine-grained SAND (SP)

Boring Terminated at 75 ft.

98,5"

98,5"

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

B-4

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: American Drilling Inc. LOGGED BY: E. Sharpe

DRILLING METHOD: SPT Boring DATE: August 28, 2023 DEPTH TO - WATER> INITIAL: 19.5 ft. AFTER 24 HOURS: CAVING>

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

Light brown fine-grained silty SAND with trace of brick

(SM)

Auger Refusal at 5 ft.

Boring Terminated at 5 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

R-1

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: E. Sharpe LOGGED BY: E. Sharpe

DRILLING METHOD: Auger Boring DATE: August 28, 2023

DEPTH TO - WATER> INITIAL: GNE AFTER 24 HOURS: CAVING>

Auger refusal due to brick and slag.

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

Brown fine-grained silty SAND with trace of brick (SM)

Auger Refusal at 4 ft.

Boring Terminated at 4 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

R-2

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: E. Sharpe LOGGED BY: E. Sharpe

DRILLING METHOD: Auger Boring DATE: August 28, 2023

DEPTH TO - WATER> INITIAL: GNE AFTER 24 HOURS: CAVING>

Auger refusal due to brick and slag.

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

Brown fine-grained silty SAND (SM)

Orange/brown fine-grained clayey SAND with trace of brick (SC)

Auger Refusal at 8 ft.

Boring Terminated at 8 ft.

PROJECT: Brickyard Road Drainage PROJECT NO.: 10116-2023153

CLIENT: Sigma Consulting Group

PROJECT LOCATION: Molino, Escambia County, Florida

TEST BORING

RECORD

R-3

LOCATION: Per Boring Location Plan ELEVATION: Existing Grade

DRILLER: E. Sharpe LOGGED BY: E. Sharpe

DRILLING METHOD: Auger Boring DATE: August 28, 2023

DEPTH TO - WATER> INITIAL: GNE AFTER 24 HOURS: CAVING>

Auger refusal due to brick and slag.

D e p th

(f e e t)

E le va ti o n

(f t-

M S

L

Description

G ra p h ic

G ro u n d w a te r

S a m p le T yp e

N -V a lu e

10 20 30 40 50 70 90

PLASTIC LIMIT LIQUID LIMIT

NATURAL MOISTURE

BLOW COUNT

%<#200

T h is i n fo rm a ti o n p e rt a in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e i n te rp re te d a s b e in g i n d ic a ti v e o f th e s it e

APPENDIX C

Laboratory Data

Lab Summary – Page 1 of 1

SUMMARY OF CLASSIFICATION & INDEX TESTING

NOVA Project Number 10116-2023153

SUMMARY OF CLASSIFICATION AND INDEX TESTING

Test

Boring

Sample

Depth

(ft. BEG)

Natural

Moisture

Percent Fines

(%<#200)

Org.

Content

Atterberg Limits

USCS

Soil

Classifica tion

Liquid Limit (LL)

Plasticity Index (PI)

B-1 6-8 7 43 --- --- --- SC

B-1 18-20 20 41 --- 31 10 CL

B-1 48-50 15 63 --- 32 13 CL

B-1 63-65 19 37 --- --- --- SC

B-2 4-6 10 33 --- --- --- SC

B-2 13-15 15 37 --- --- --- SC

B-2 68-70 25 9 --- --- --- SP-SM

B-3 13-15 17 30 --- --- --- SC

B-3 23-25 14 10 15 --- --- SP-SM

B-3 43-45 42 49 4 --- --- SC

B-3 53-55 18 78 --- 49 26 CL

B-4 18-20 19 18 --- --- --- SM

B-4 48-50 18 79 --- 33 13 CL

T h e s e r e s u lt s a re f o r th e e x c lu s iv e u s e o f th e c lie n t fo r w h o m t h e y w e re o b ta in e d

T h e y a p p ly o n ly t o t h e s a m p le s t e s te d a n d a re n o t in d ic a ti v e o f a p p a re n tl y i d e n ti c a l s a m p le s

Tested By: E. Sharpe Checked By: J. James

LIQUID AND PLASTIC LIMITS TEST REPORT

P L

A S

T

IC

IT

Y

I N

D E

X

LIQUID LIMIT

0 10 20 30 40 50 60 70 80 90 100 110

CL-ML

C L o r O L

C H o r O H

ML or OL MH or OH

Dashed line indicates the approximate upper limit boundary for natural soils

MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS

Project No. Client: Remarks:

Project:

Nova Engineering & Environmental

Pensacola, FL Figure

Source of Sample: B-1 Depth: 18

Source of Sample: B-1 Depth: 48

Gray very soft to medium stiff low-plasticity CLAY (CL) 30.9 21.0 9.9 51 CL

Gray very stiff to hard low-plasticity CLAY (CL) 32.1 18.9 13.2 63 CL

2023153 Sigma Consulting Group e s e r e s u lt s a re f o r th e e x c lu s iv e u s e o f th e c lie n t fo r w h o m t h e y w e re o b ta in e d

T h p ly o n ly t o t h e s a m p le s t e s te d a n d a re n o t in d ic a ti v e o f a p p a re n tl y i d e n ti c a l s a m p le s

Tested By: E. Sharpe Checked By: J. James

LIQUID AND PLASTIC LIMITS TEST REPORT

P L

A S

T

IC

IT

Y

I N

D E

X

LIQUID LIMIT

0 10 20 30 40 50 60 70 80 90 100 110

CL-ML

C L o r O L

C H o r O H

ML or OL MH or OH

Dashed line indicates the approximate upper limit boundary for natural soils

MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS

Project No. Client: Remarks:

Project:

Nova Engineering & Environmental

Pensacola, FL Figure

Source of Sample: B-3 Depth: 53

Brown/gray very stiff low-plasticity CLAY (CL) 48.7 23.2 25.5 78 CL e s e r e s u lt s a re f o r th e e x c lu s iv e u s e o f th e c lie n t fo r w h o m t h e y w e re o b ta in e d

T h p ly o n ly t o t h e s a m p le s t e s te d a n d a re n o t in d ic a ti v e o f a p p a re n tl y i d e n ti c a l s a m p le s

Tested By: E. Sharpe Checked By: J. James

LIQUID AND PLASTIC LIMITS TEST REPORT

P L

A S

T

IC

IT

Y

I N

D E

X

LIQUID LIMIT

0 10 20 30 40 50 60 70 80 90 100 110

CL-ML

C L o r O L

C H o r O H

ML or OL MH or OH

Dashed line…