Report_of_Geotechnical_Explration.pdf

TIERRA

REPORT OF GEOTECHNICAL EXPLORATION

Crystal Beach Park Okaloosa County, Florida

Tierra Project No. 4511-22-002

Prepared for:

Baskerville-Donovan, Inc.

449 West Main Street Pensacola, Florida 32502

Attn: Mr. Michael Langston, PE

Prepared by:

Tierra, Inc.

1300 West Main Street Pensacola, Florida 32502

February 21, 2022

1300 West Main Street Pensacola, FL 32502tt MMM ii SSStt tt PPP lll F Phone (850) 462-8774 Fax (850) 462-8784

TIERRA

February 21, 2022

Baskerville-Donovan, Inc.

449 West Main Street Pensacola, Florida 32502 Attn: Mr. Michael Langston, PE

Subject: Crystal Beach Park Okaloosa County, Florida Tierra Project No. 4511-22-002

Mr. Langston:

Thank you for choosing Tierra, Inc. (Tierra) as your Geotechnical consultant. Per your authorization, we have completed the Geotechnical exploration for the subject project. The results of the study are discussed in this report.

Should you have any questions regarding the enclosed report or the project in general, please do not hesitate to contact us at (850) 462-8774.

Sincerely, TIERRA, INC. Mitchell L Smith 2022.02.21

16:31:10-06'00'

Matthew McCoy, EI Geotechnical Engineer Principal Geotechnical Engineer

Florida License No. 43416

Mitchell L. Smith, PE

1300 West Main Street Pensacola, FL 32502 Phone (850) 462-8774 Fax (850) 462-8774 https://2022.02.21

TABLE OF CONTENTS

1.0 PROJECT INFORMATION

1.1 Project Authorization

1.2 Project Description

1.3 Purpose and Scope of Services

2.0 SITE AND SUBSURFACE CONDITIONS

2.1 Site Location and Description

2.2 Subsurface Conditions

2.3 Groundwater Conditions

2.4 Laboratory Soil Testing

Table 1 – Laboratory Falling Head Permeability Test Results

3.0 EVALUATION AND RECOMMENDATIONS

3.1 General Comments

3.2 Timber Pile Foundation Recommendations

Table 2 –Allowable Timber Pile Compression & Tension Capacities

3.3 Pile Group Action

3.4 Settlement

3.5 Stormwater Management Facility Recommendations

4.0 REPORT LIMITATIONS

APPENDIX A

Boring Location Plan and Soil Profiles Falling Head Permeability Test Results

Mr. Michael Langston, PE – Baskerville-Donovan, Inc. February 21, 2022 Crystal Beach Park Page 1 of 7

1.0 PROJECT INFORMATION

1.1 Project Authorization

Authorization to proceed on this project was issued by Mr. Michael Langston, PE with Baskerville- Donovan, Inc. (BDI). A formal contract has been executed between Tierra, Inc. (Tierra) and BDI for these services.

1.2 Project Description

Based on the information provided, we understand that a new 600 sf restroom facility will be constructed in the southeast corner of the expanded Crystal Beach Park. The single-story off-grade structure will be founded on timber piles. Based on information provided by the structural engineer, Mr. Steve Leonard, PE (Berube Leonard, LLC), a pile compression capacity on the order of 10 tons is desired.

Two drainage swale areas are proposed to manage stormwater runoff from the proposed improvements. The treatment swales are expected to be relatively shallow (less than 3 feet deep).

If any of the project information noted above is incorrect or has changed, please inform Tierra so that we may amend the recommendations presented in this report, if necessary.

1.3 Purpose and Scope of Services

The purpose of this exploration was to evaluate the subsurface conditions present in the subject area and to render timber pile foundation recommendations as well as parameters for stormwater drawdown analysis for the proposed stormwater treatment facilities.

The exploration consisted of one 35 foot deep Standard Penetration Test (SPT) boring to evaluate the subsurface conditions for the restroom and two 7 foot to 10 foot deep auger borings in the proposed treatment swale areas; laboratory soil testing including water content tests, wash #200 sieve tests, and falling head permeability tests; and a site visit, visual classification of the soil samples, and analysis by our engineering staff.

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2.0 SITE AND SUBSURFACE CONDITIONS

2.1 Site Location and Description

The site is located south of Scenic Highway 98 near the intersection of Hutchinson Street in Okaloosa County, Florida. The property fronts the Gulf of Mexico. An aerial photograph depicting the site location is shown on the Boring Location Plan (Appendix A).

At the time of our exploration, a residential property was present immediately east of the existing Crystal Beach park. The eastern-most residential property located near the proposed restroom facility was demolished in preparation for the park expansion.

Based on review of the topographic survey provided as well as the survey data on Google Earth, the site slopes downward from the north (at/near EL +22 feet) to the south (at/near EL +10 feet).

2.2 Subsurface Conditions

The Boring Location Plan and the Soil Profiles of the borings drilled for this study can be found in Appendix A. The borings were field located and staked using a Garmin GPSMap 64ST Global Positioning System (GPS) unit with a reported accuracy of ±1 meter. Therefore, the boring locations should be considered approximate.

We have estimated ground surface elevations at the boring locations using the topographic survey provided as well as the topographic information provided in Google Earth. The subsurface conditions encountered will be discussed in general terms below.

The restroom boring (B-1) generally encountered very loose sand from the ground surface (approximately EL +19 feet) to a depth of approximately 18 feet below existing grade (or to approximately EL +1 feet) underlain by dense sand to the bottom of the 35 foot deep boring (terminated at approximately EL -16 feet).

The treatment swale auger borings (AB-1 and AB-2) generally encountered sand from the ground surface (approximately EL +19 feet) to the bottom of the 7 foot to 10 foot deep borings.

The above subsurface descriptions are of a generalized nature, provided to highlight the major soil stratum encountered. The Soil Profiles should be reviewed for specific subsurface conditions at each boring location. The stratification shown on the Soil Profiles represents the subsurface

Crystal Beach Park Page 3 of 7 conditions at the actual boring locations only, and variations in the subsurface conditions can and may occur between boring locations and should therefore be expected. The stratification represents the approximate boundary between subsurface materials, and the transitions between strata may be gradual.

2.3 Groundwater Conditions

Groundwater was encountered in SPT boring B-1 at approximately 15 feet below existing grade at the time of drilling, which was during a period of below-normal seasonal rainfall. Based on the ground surface elevation at the boring location estimated from the topographic survey and Google Earth, this corresponds to groundwater elevation of approximately +4 feet NAVD 88.

Groundwater levels will fluctuate with rainfall and tides and could vary several feet during typical seasonal fluctuations. Larger fluctuations are possible under severe weather conditions. We recommend that the Contractor determine the actual groundwater levels at the time of construction to determine potential impacts groundwater can/will have on construction procedures.

2.4 Laboratory Soil Testing

Laboratory soil testing consisted of water content tests, wash #200 sieve tests, and falling head permeability tests. The results of the tests can be found on the Soil Profiles opposite the samples tested.

Falling head permeability tests were performed on remolded bulk samples of the more permeable soil strata encountered in the treatment swale borings. The densities to which the samples were remolded were based on the Nf values obtained from the SPT test boring nearby. The results of the tests are summarized in Table 1 below. The laboratory permeability test data sheets are attached in Appendix A.

TABLE 1 - LABORATORY FALLING HEAD PERMEABILITY TEST RESULTS

Soil Stratum Boring

Sample Elevation,

ft. NAVD 88 Sample Description %

Fines Dry

Density, pcf

Vertical Permeability, ft/day

1 AB-1 18.5 to 12 Light brown, white SAND 0.2 95.9 57.4

1 AB-2 15.5 to 9 Light brown, white SAND 0.4 97.8 28.4

Crystal Beach Park Page 4 of 7

3.0 EVALUATION AND RECOMMENDATIONS

3.1 General Comments

Based on our understanding of the proposed facility, the exploration encountered subsurface conditions that will provide adequate support for the proposed structure provided the recommendations presented in this report are followed.

The subsurface conditions encountered in the treatment swale borings are suitable for conventional dry treatment. Stormwater design parameters are presented in Section 3.5 below.

3.2 Timber Pile Foundation Recommendations

We have evaluated compression and tension pile capacities for 6-inch, 8-inch, and 10-inch tip diameter timber piles to support the proposed restroom facility. Table 2 below shows allowable compression and tension capacities for driven timber piles with a tip elevation of -6 feet NAVD 88 (note – all elevations referenced to NAVD 88). The capacities presented in Table 2 assume a pile butt elevation of +24 feet, a ground surface elevation of +19 feet (no scour), include a Factor of Safety of 2, and assume jetting or predrilling the piles to elevation +6 feet to aide in standing the piles prior to driving.

TABLE 2

ALLOWABLE TIMBER PILE COMPRESSION & TENSION CAPACITIES

Pile Size Allowable Compression Capacity Allowable Tension Capacity

6-inch Diameter Timber Pile 5 tons 2 tons

8-inch Diameter Timber Pile 10 tons 3 tons

10-inch Diameter Timber Pile 15 tons 4 tons i Groundwater Leve

SHWT to be a r ation +6 feet

Vertical Permeability average vertical permeability of 42.9 ft/day for Stratum 1 would be reasonable for modeli

Crystal Beach Park Page 5 of 7

3.3 Pile Group Action

No reductions of the individual pile capacities will be required if piles are spaced center-to-center a minimum of 3 times their width/diameter. If piles are spaced closer, our office should be notified so that pile capacity reductions can be evaluated.

3.4 Settlement

Settlements of driven pile foundations are typically small and should not be a concern on this project provided the piles are embedded as recommended herein. Pile head settlements should be on the order of ½ inch or less. Group settlements are estimated to be on the same order of magnitude for the expected lightly loaded structure.

3.5 Stormwater Management Facility Recommendations

The subsurface conditions encountered in the treatment swale auger borings are suitable for conventional dry treatment of stormwater runoff. Geotechnical parameters for analysis/design are presented below:

Effective Aquifer Thickness: A confining unit, which would hydrogeologically define the thickness of the surficial aquifer, was not encountered to a depth of 35 feet below existing grade (the deepest boring drilled on the site). For the purposes of modeling, we recommend setting the bottom of the aquifer no deeper than the bottom of the boring elevation (elevation -16 feet). Note that a shallower effective aquifer thickness for modeling a shallow swale may be more appropriate, and a sensitivity analysis using this parameter is warranted.

Groundwater was encountered at approximately EL +4 feet at the time of drilling. Given that the boring was drilled during a period of below-normal rainfall and when tides are typically at their lowest, we have estimated the “normal” t/nea elev .SHWT to be at/near elevation +6 feet.

: Vertical flow from the bottom of the treatment swales will be controlled by the vertical permeability of the soil immediately beneath the bottom of the swale.

Based on the results of the falling head permeability tests (Table 1), anan average vertical

Seasonal H gh l:Seasonal High Groundwater Level:

Vertical Permeability ng.permeability of 42.9 ft/day for Stratum 1 would be reasonable for modeling .

Horizontal Permeability herefore, a Kh value of 64.4 ft/day would be reasonable for modeling the Stratum 1 material

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Horizontal Permeability: Horizontal flow from the pond will be through the Stratum 1 soils.

The horizontal permeability of Stratum 1 has been estimated based on the results of the vertical permeability tests and extensive experience with similar soils from field permeability tests. While horizontal permeabilities have generally been found to range from 3 to 10 times higher than vertical permeabilities of regional deposits, we recommend that a multiplier of 3 with a factor of safety of 2 be used for design (effectively, a 1.5 multiplier). Therefore, a Kh value of 64.4 ft/day would be reasonable for modeling the Stratum 1 materials s (42.9 ft/day x 1.5).

Effective Porosity: Based on the fines contents of the soils encountered in the test borings, an effective porosity of 0.30 would be appropriate for modeling the Stratum 1 soils.

Crystal Beach Park Page 7 of 7

4.0 REPORT LIMITATIONS

The recommendations submitted are based on the available soil information obtained by Tierra, Inc.

and design details furnished by Baskerville-Donovan for the subject project. If there are any revisions to the plans for this project or if deviations from the subsurface conditions noted in this report are encountered during construction, Tierra should be notified immediately to determine if changes in the foundation, or other, recommendations are required. If Tierra is not retained to perform these functions, we cannot be responsible for the impact of such conditions on the performance of the project.

The findings, recommendations, specifications, and professional advice contained herein have been made in accordance with generally accepted professional Geotechnical engineering practices in the local area.

After the plans and specifications are more complete, the Geotechnical engineer should be provided the opportunity to review the final design plans and specifications to assure our engineering recommendations have been properly incorporated into the design documents. At that time, it may be necessary to submit supplementary recommendations. This report has been prepared for the exclusive use of Baskerville-Donovan for the specific application to the subject project.

APPENDIX A

Boring Location Plan and Soil Profiles

Falling Head Permeability Test Results

BORING LOCATION PLAN SOIL PROFILES

0 40'

PLAN SCALE

BOR # AB-1 BOR # AB-2 BOR # B-1

EASTING 1361202 EASTING 1361331 EASTING 1361325

NORTHING 507888 NORTHING 507885 NORTHING 507816

ELEV. 19.0 ELEV. 19.0 ELEV. 19.0

DATE 1/13/2022 DATE 1/13/2022 DATE 2/8/2022

DRILLER M. DAVIS DRILLER M. DAVIS DRILLER R. SHUEY

HAMMER AUTOMATIC

RIG D-25

20 20GNE GNE N

-200 = 1

115 NMC = 4 4 15

-200 = 1 1 2

NMC = 2

-200 = 110 10

NMC = 5 2

AB-2

AB-1

E L

E V

A T

IO

N

IN

F

E E

T

N G

V D

-200 = 15

NMC = 22 8

0 0

-5 -5

-200 = 3-10 -10

NMC = 23 19

E L

E V

A T

IO

N

IN

F

E E

T

N G

V D

B-1

-15 -15

-20 -20

AUTOMATIC HAMMER

NOTE: BASE MAP PROVIDED BY BASKERVILLE-DONOVAN, INC. SPT

RELATIVE DENSITY

GRANULAR MATERIALS-

(BLOWS/FT.)

VERY LOOSE LESS THAN 3

LOOSE 3 TO 8

MEDIUM 8 TO 24

LIGHT BROWN, WHITE SAND (SP) N SPT N-VALUE IN BLOWS/FOOT FOR 12 INCHES EASTING EASTING COORDINATE REFERENCED TO THE FLORIDA STATE

LEGEND

DENSE 24 TO 40

1 PLANE COORDINATE SYSTEM, FLORIDA NORTH ZONE, N.A.D. 83 VERY DENSE GREATER THAN 40

DETERMINED USING HAND-HELD GARMIN GPS MAP 64 ST GPS

OF PENETRATION (UNLESS OTHERWISE NOTED)

SILTS AND CLAYS SPT

SP UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D 2488) GROUP GLOBAL POSITIONING SYSTEM WITH A REPORTED ACCURACY CONSISTENCY (BLOWS/FT.)

OF +/- 1 METER.SYMBOL AS DETERMINED BY VISUAL REVIEW AND LABORATORY VERY SOFT LESS THAN 1

INVESTIGATION

GROUNDWATER LEVEL ENCOUNTERED DURING

TESTING ON SELECTED SAMPLES FOR CONFIRMATION OF VISUAL SOFT 1 TO 3

REVIEW. NORTHING NORTHING COORDINATE REFERENCED TO THE FLORIDA STATE FIRM 3 TO 6

ESTIMATED "NORMAL" SEASONAL HIGH PLANE COORDINATE SYSTEM, FLORIDA NORTH ZONE, N.A.D. 83 STIFF 6 TO 12

GROUNDWATER TABLE DETERMINED USING HAND-HELD GARMIN EGARMIN GPS MAP 64 ST

GNE GROUNDWATER TABLE NOT ENCOUNTERED VERY STIFF 12 TO 24

GPS GLOBAL POSITIONING SYSTEM WITH A REPORTED ACCURACY HARD GREATER THAN 24

APPROXIMATE LOCATION OF AUGER BORING OF +/- 1 METER.

-200 PERCENT PASSING #200 SIEVE

APPROXIMATE LOCATION OF SPT BORING NMC NATURAL MOISTURE CONTENT (%) ELEV. GROUND SURFACE ELEVATION ESTIMATED FROM GOOGLE EARTH

AND TOPOGRAPHIC SURVEY PROVIDED BY CLIENT.

ENGINEER OF RECORD:DRAWN BY: APPROVED BY: GEOTECHNICAL ENGINEERING SERVICES

SCALE: PROJECT NUMBER:SW MITCHELL L. SMITH, P.E.MLS

FLORIDA LICENSE NO.: SHEET 1TIERRA NOTED 4511-22-002 CRYSTAL BEACH PARKDATE:CHECKED BY: 1300 West Main Street43416 Pensacola, Florida 32502FEB 2022MMC Phone: 850-462-8774 Fax: 850-462-8784 OKALOOSA COUNTY, FLORIDA

FALLING HEAD PERMEABILITY TEST

Project Name: Crystal Beach Park Date: 1/21/2022 Project Number: 4511-22-002 Sample Location: AB-1, EL +18.5 to +12.0 feet Technician: DH Sample Description: Light brown, white SAND (Stratum 1) Soil Classification: SP Remolded Compactive Effort: Standard Proctor No. of Layers: 3 Blows Per Layer: 25

Assumes: 1. Standard Proctor Mold (L = 4.5 in.) Remolded Test Sample Density

2. 1/2 Inch Diameter Tubing

(2.3*a*L) log (h1/h2)

K

V =

(A) (Delta t) where a =

1.267 cm (area of tube)

L =

4.5 in. (height of soil sample)

11.43 cm (L = 4.5 in. for full mold)

A =

12.57 sq. in. (area of Proctor mold)

81.1 sq. cm

Can # 1 Wt. Can + Wet Soil, g 388.6 Wt. Can + Dry Soil, g 369.7 Wt. of Water, g 18.9 Wt. of Can, g 260.1 Wt. of Dry Soil, g 109.6 Moisture Content, % 17.2% Wt. Wet Soil + Mold, lbs. 8.2 Wt. of Mold, lbs. 4.5 Wt. of Wet Soil, lbs. 3.7 Wet Density, pcf 112.4 Dry Density, pcf 95.9

Fines Content of Test Sample

Head Time (sec) Avg. Time (sec) (ft) Run #1 Run #2

7 0 0 0 6 1 1 1.0 5 3 3 3.0 4 5 5 5.0 3 8 8 8.0 2 11 11 11.0 1 17 17 17.0 h1 h2 Delta t (sec) KV (cm/sec) 7 1 17 2.0E-02 6 1 16 2.0E-02 7 2 11 2.0E-02

Can # 1 Wt. Can + Wet Soil, g 249.6 Wt. Can + Dry Soil, g 245.4

Wt. of Water, g 4.2 Wt. of Can, g 127.1 Wt. of Dry Soil, g 118.3 Wt. of Dry Sample After Washing + Can, g 245.2 Wt. of Soil Lost During Washing, g 0.2 Moisture Content, % 3.6% Percent Fines, % 0.2%

Average KV = 2.0E-02 cm/sec

57.4 ft/day

FALLING HEAD PERMEABILITY TEST

Project Name: Crystal Beach Park Date: 1/21/2022 Project Number: 4511-22-002 Sample Location: AB-2, EL +15.5 to +9.0 feet Technician: DH Sample Description: Light brown, white SAND (Stratum 1) Soil Classification: SP Remolded Compactive Effort: Standard Proctor No. of Layers: 3 Blows Per Layer: 25

Assumes: 1. Standard Proctor Mold (L = 4.5 in.) Remolded Test Sample Density

2. 1/2 Inch Diameter Tubing

(2.3*a*L) log (h1/h2)

K

V =

(A) (Delta t) where a =

1.267 cm (area of tube)

L =

4.5 in. (height of soil sample)

11.43 cm (L = 4.5 in. for full mold)

A =

12.57 sq. in. (area of Proctor mold)

81.1 sq. cm

Can # 1 Wt. Can + Wet Soil, g 370.8 Wt. Can + Dry Soil, g 354.3 Wt. of Water, g 16.5 Wt. of Can, g 260.1 Wt. of Dry Soil, g 94.2 Moisture Content, % 17.5% Wt. Wet Soil + Mold, lbs. 8.3 Wt. of Mold, lbs. 4.5 Wt. of Wet Soil, lbs. 3.8 Wet Density, pcf 115.0 Dry Density, pcf 97.8

Fines Content of Test Sample

Head Time (sec) Avg. Time (sec) (ft) Run #1 Run #2

7 0 0 0 6 3 3 3.0 5 6 6 6.0 4 10 10 10.0 3 15 15 15.0 2 22 22 22.0 1 35 35 35.0 h1 h2 Delta t (sec) KV (cm/sec) 7 1 35 9.9E-03 6 1 32 1.0E-02 7 2 22 1.0E-02

Can # 2 Wt. Can + Wet Soil, g 276.9 Wt. Can + Dry Soil, g 274.2

Wt. of Water, g 2.7 Wt. of Can, g 126.1 Wt. of Dry Soil, g 148.1 Wt. of Dry Sample After Washing + Can, g 273.6 Wt. of Soil Lost During Washing, g 0.6 Moisture Content, % 1.8% Percent Fines, % 0.4%

Average KV = 1.0E-02 cm/sec

28.4 ft/day