Attachment_Z_-_Geotech_Report.pdf

1675 Lee Road

Winter Park, FL 32789

P (407) 740-6110

Terracon.com

Facilities | Environmental | Geotechnical | Materials

Report Cover Letter to Sign

September 4, 2025

Kimley-Horn

200 South Orange Avenue, Suite 600

Orlando, Florida 32801

Attn: Mr. Scott Mingonet, PLA, AICP

P: 407-427-1622

E: Scott.Mingonet@kimley-horn.com

Re: Supplemental Geotechnical Engineering Report

Alexander Island – Fort Florida Road Entrance

Debary, Florida

Terracon Project No. H1245008

Dear Mr. Mingonet:

We have completed the scope of Supplemental Geotechnical Engineering services for the above referenced project in general accordance with our proposal for additional geotechnical engineering services dated July 9, 2025. This supplemental report presents the findings of the additional subsurface exploration along Fort Florida Road and provides geotechnical recommendations concerning pavement conditions relative to the entrance driveway construction for the proposed recreational park. This report should be considered supplemental to the Geotechnical Engineering Report prepared for Alexander

Island dated April 18, 2024.

Field Exploration

The additional field exploration consisted of two pavement cores with hand auger borings to a depth of 5 feet below the existing ground surface along Fort Florida Road near the proposed entrance driveway location. The approximate boring/core locations are presented on the attached Exploration Plan. Photographs of the pavement cores are attached.

The cores found an asphalt surface consisting of 4-5/8 to 4-7/8 inches of Type S and SP asphalt over sand and sand with silt with trace to some shell. A lens of silty sand with trace shell was found at location FFR-2 at about 2.5 to 3.5 feet below existing grade. A pavement base was not observed. Groundwater was found at a depth of about 4 to 4-

1/2 feet below existing grade during the field exploration (July of 2025). Detailed soil conditions observed are presented on the attached Boring Logs.

Supplemental Geotechnical Engineering Report

Alexander Island – Fort Florida Road Entrance | Debary, Florida

September 4, 2025 | Terracon Project No. H1245008

Geotechnical Evaluations

Based on the soil and groundwater conditions observed during the field exploration, and our understanding of the project, we offer the following geotechnical engineering considerations and evaluations:

Using a structural coefficient of 0.34 for the asphalt in good condition (Table 7.1 of the

FDOT Flexible Pavement Design Manual), the in-place asphalt has a structural number of about 1.6. The borings were not adequate to obtain a soil sample for Limerock Bearing

Ratio (LBR) testing. If we assume the sands below the asphalt have an LBR value of at least 30, a structural coefficient of 0.06 could be considered for the subgrade soils, increasing the structural number to about 2.0.

A typical minimum asphalt pavement section (consisting to 1-1/2 inches of asphalt over

6 inches of base and 12 inches of stabilized subgrade) has a structural number of 2.3.

This would be appropriate for passenger vehicle parking areas and driveways with relatively light traffic loads (i.e. infrequent heavy trucks) and relatively low traffic volumes.

A heavier asphalt pavement section (maybe consisting of 2-1/2 inches of asphalt over 8 inches of base and 12 inches of stabilized subgrade) would have a structural number of about 3.3. This pavement section would generally be appropriate for main entry driveways and where occasional heavy loads and higher traffic volume are anticipated.

The existing pavement section along Fort Florida Road could be appropriate for relatively light traffic loads and frequency with a 1-inch overlay, or preferably ½ inch milling with a 1.5 inch overlay. The required structural number for the pavement section along Fort

Florida Road should consider the anticipated traffic volume and frequency of heavy trucks. To provide equivalency to the heavier section above would require a ½ inch milling and 3 inch overlay.

For the entrance driveway, soil conditions observed at the recent core/boring location and the previous exploration appear suitable for normal pavement sections designed based on anticipated traffic conditions. Recommendations regarding earthwork/site preparation and pavement section design presented in the previous report dated April

18, 2024 are suitable for the entrance roadway. If anticipated traffic counts and loading conditions are not known so that the lighter pavement section can be justified, we suggest using the heavier pavement section presented in the previous report for the entrance drive at this site.

Facilities | Environmental | Geotechnical | Materials 1

General Comments

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration.

Variations will occur between exploration point locations or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the

Geotechnical Engineer, where noted in the April 18, 2024 report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and any work product is limited to our client and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly affect excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Site safety and cost estimating including excavation support and dewatering requirements/design are the responsibility of others.

Construction and site development have the potential to affect adjacent properties. Such impacts can include damages due to vibration, modification of groundwater/surface water flow during construction, foundation movement due to undermining or subsidence from excavation, as well as noise or air quality concerns. Evaluation of these items on nearby properties are commonly associated with contractor means and methods and are not addressed in this report. The owner and contractor should consider a preconstruction/precondition survey of surrounding development. If changes in the

Facilities | Environmental | Geotechnical | Materials 2 nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

Terracon appreciates the opportunity to be of continued service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Certificate of Authorization No. 8830

Shenna McMaster, P.E. Jay W. Casper, P.E.

Senior Geotechnical Engineer Senior Principal

FL Registration No. 57537

Attachments:

■ Exploration Plan

■ Photographs

■ Boring Logs

This item has been digitally signed and sealed by Shenna McMaster, P.E. on the date adjacent to the seal.

Signature must be verified on any electronic copies.

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Exploration Plan

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY GOOGLE EARTH

Pavement Cores

Alexander Island – Fort Florida Road | Debary, Florida

Terracon Project No. H1245008

Core FFR – 1: 4-7/8 inches of asphalt

Core FFR-1 Location

Pavement Cores

Alexander Island – Fort Florida Road | Debary, Florida

Terracon Project No. H1245008

Core FFR-2: 4-5/8” Asphalt

Core FFR-2 Location

4-7/8'' ASPHALT

SAND (SP), brown

SAND WITH SILT (SP-SM), with shell, brown

SAND WITH SILT (SP-SM), trace shell, gray

Boring Terminated at 5 Feet

Boring Log No. FFR-1

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

6.15.5

0.4

1.0

4.5

5.0

Advancement MethodNotes

Water Level Observations Groundwater observed at 4.5 ft

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Alexander Island - Phase 1

642 Fort Florida Rd, | DeBary, FL

Terracon Project No. H1245008 Winter Park, FL

1675 Lee Rd

Drill Rig

Driller

MARK C.

Logged by

Boring Started 07-29-2025

Boring Completed 07-29-2025

Abandonment Method

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

)See Exploration PlanLocation:

Latitude: 28.8562° Longitude: -81.3481°

Depth (Ft.)

Until 4-5/8'' ASPHALT

SAND WITH SILT (SP-SM), with shell, brown

SILTY SAND (SM), trace shell, gray

SAND WITH SILT (SP-SM), dark brown gray

Boring Terminated at 5 Feet

Boring Log No. FFR-2

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

6.717.2

0.4

2.5

3.5

5.0

Advancement MethodNotes

Water Level Observations Groundwater observed at 4 ft

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Alexander Island - Phase 1

642 Fort Florida Rd, | DeBary, FL

Terracon Project No. H1245008 Winter Park, FL

1675 Lee Rd

Drill Rig

Driller

MARK C.

Logged by

Boring Started 07-29-2025

Boring Completed 07-29-2025

Abandonment Method

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

)See Exploration PlanLocation:

Latitude: 28.8561° Longitude: -81.3478°

Depth (Ft.)

Unified Soil Classification System

Criteria for Assigning Group Symbols and Group Names Using

Laboratory Tests A

Soil Classification

Group

Symbol Group Name B

Coarse-Grained Soils:

More than 50% retained on No. 200 sieve

Gravels:

More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu≥4 and 1≤Cc≤3 E GW Well-graded gravel F

Cu<4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F, G, H

Fines classify as CL or CH GC Clayey gravel F, G, H

Sands:

50% or more of coarse fraction passes No. 4 sieve

Clean Sands:

Less than 5% fines D

Cu≥6 and 1≤Cc≤3 E SW Well-graded sand I

Cu<6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G, H, I

Fines classify as CL or CH SC Clayey sand G, H, I

Fine-Grained Soils:

50% or more passes the

No. 200 sieve

Silts and Clays:

Liquid limit less than

Inorganic:

PI > 7 and plots above “A” line J CL Lean clay K, L, M

PI < 4 or plots below “A” line J ML Silt K, L, M

Organic:

𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑

𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑

< 0.75 OL

Organic clay K, L, M, N

Organic silt K, L, M, O

Silts and Clays:

Liquid limit 50 or more

Inorganic:

PI plots on or above “A” line CH Fat clay K, L, M

PI plots below “A” line MH Elastic silt K, L, M

Organic:

𝐿𝐿 𝑜𝑣𝑒𝑛 𝑑𝑟𝑖𝑒𝑑

𝐿𝐿 𝑛𝑜𝑡 𝑑𝑟𝑖𝑒𝑑

< 0.75 OH

Organic clay K, L, M, P

Organic silt K, L, M, Q

Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-inch (75-mm) sieve.

B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name.

C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.

D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay.

E Cu = D60/D10 Cc =

F If soil contains ≥ 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains ≥ 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or

“with gravel,” whichever is predominant.

L If soil contains ≥ 30% plus No. 200 predominantly sand, add

“sandy” to group name.

M If soil contains ≥ 30% plus No. 200, predominantly gravel, add

“gravelly” to group name.

N PI ≥ 4 and plots on or above “A” line.

O PI < 4 or plots below “A” line.

P PI plots on or above “A” line.

Q PI plots below “A” line.

DxD

)(D