Attachment__A_-_Geotechnical_Report.pdf

Ardaman & Associates, Inc.

CORPORATE HEADQUARTERS

8008 S. Orange Avenue, Orlando, Florida 32809 - Phone: (407) 855-3860 Fax: (407) 859-8121

Branch Office Locations

Florida: Bartow, Cocoa, Fort Myers, Miami, Orlando, Port St. Lucie, Sarasota, Tallahassee, Tampa, West Palm Beach

Louisiana: Baton Rouge, New Orleans, Shreveport

Texas: Houston

MEMBERS:

ASTM International

Society of American Military Engineers

American Council of Engineering Companies

Subsurface Exploration and

Geotechnical Engineering Evaluation

Culvert Improvements

Cocoa, Florida

1300 N. Cocoa Boulevard, Cocoa, Florida 32922 Phone: (321) 632-2503

Florida: Bartow, Cocoa, Fort Myers, Miami, Orlando, Port St. Lucie, Sarasota, Tallahassee, Tampa, West Palm Beach

Louisiana: Baton Rouge, New Orleans, Shreveport

Texas: Houston

July 16, 2024

File No. 24-23-5253

DRMP, Inc.

8000 Regency Parkway, Suite 110

Cary, NC 27518

Attention: Mr. Ryan Mitchell, PE

Subject: Subsurface Exploration and

Geotechnical Engineering Evaluation

Culvert Improvements

Lake Drive

Cocoa, Florida

Dear Mr. Mitchell:

As requested and authorized, we have completed a subsurface exploration and geotechnical engineering evaluation for the subject project. The purposes of performing this exploration were to evaluate the general subsurface conditions within the proposed culvert areas and to provide recommendations for site preparation. This report documents our findings and presents our engineering recommendations.

SITE LOCATION AND SITE DESCRIPTION

The site for the proposed culverts is located near the intersection of Lake Drive and Cherry Laurel

Avenue in Cocoa, Florida (Section 30, Township 24 South, Range 36 East). The general site location is shown superimposed on the Lake Poinsett, Florida U.S.G.S. quadrangle map presented on Figure 1.

The project area consists of grassed shoulders adjacent to the existing asphalt paved roadways of Lake Drive and Cherry Laurel Avenue. An existing drainage ditch that runs parallel to Lake

Drive is also located within the project area. The properties surrounding the roadways and ditch in the project area consist of single family residences and undeveloped wooded properties.

Ardaman & Associates, Inc.

Geotechnical, Environmental and Materials Consultants

DRMP

File No. 24-23-5253 -2-

PROPOSED CONSTRUCTION AND GRADING

It is our understanding that the proposed construction includes the replacement of three existing culvert structures within the existing drainage ditch on the north side of Lake Drive. Additionally, a new culvert will be installed beneath Lake Drive a short distance west of the intersection with

Cherry Laurel Avenue. We understand that these structures will not be placed deeper than 10 feet below the existing ground surface adjacent to the drainage ditch. If actual structure depths exceed our assumptions, then the recommendations in this report may not be valid.

REVIEW OF SOIL SURVEY MAPS

Based on information obtained online from the Web Soil Survey as operated by the U.S.

Department of Agriculture Natural Resources Conservation Services, the site is located in an area mapped as the “Myakka sand, 0 to 2 percent slopes” soil series on the west portion of the site and the “Terra Ceia muck, frequently flooded” soil series on the east portion of the site. A description of these soil types, as obtained from the Soil Survey, is provided below.

Myakka sand, 0 to 2 percent slopes (#36):

“Myakka sand, 0 to 2 percent slopes” is a nearly level, poorly drained soil found in drainageways on flatwoods on marine terraces. A representative profile consists of fine sand to 80 inches. The water table is at a depth of 6 to 18 inches according to the Web Soil Survey.

Terra Ceia muck, frequently flooded (#64):

“Terra Ceia muck, frequently flooded” is a nearly level very poorly drained soil found on flood plains on marine terraces. A representative soil profile consists of muck to a depth of approximately 70 inches. The groundwater table is at or near the existing ground surface according to the Web Soil Survey.

FIELD EXPLORATION PROGRAM

SPT Borings

The field exploration program included performing five Standard Penetration Test (SPT) borings at the proposed culvert locations. The SPT borings were advanced to a depth of 15 feet below the ditch top of bank or existing ground surface generally using the methodology outlined in ASTM

D-1586. A summary of this field procedure is included in the Appendix.

Soil samples recovered during performance of the borings were visually classified in the field and representative portions of the samples were transported to our laboratory in sealed sample jars.

File No. 24-23-5253 -3-

The groundwater level at each of the boring locations was measured during drilling. The borings were backfilled with soil cuttings upon completion.

Hand Probes

Hand probes were performed within the existing drainage ditch at each of the three culverts that will be replaced on the project site. Hand probes are conducted by hand pushing a ½-inch diameter steel rod into the ditch bottom until penetration is refused. Generally, the probes can be pushed through very soft organic, silty, and/or clayey soils, and terminate upon encountering sandy soils or relatively stiff clays. Probes can also terminate on obstructions such as roots or buried debris. It is possible that probes could terminate under one of the above scenarios, while muck could exist below the probed depth. Therefore, hand probe data should be considered preliminary. The results of the hand probes are outlined in the General Subsurface Conditions section of this report.

Test Locations

The approximate locations of the borings are schematically illustrated on an aerial photograph plan shown on Figure 2. These locations were determined in the field by estimating distances from existing site features and should be considered accurate only to the degree implied by the method of measurement used.

LABORATORY PROGRAM

Representative soil samples obtained during our field sampling operation were packaged and transferred to our laboratory for further visual examination and classification. The soil samples were classified using visual-manual procedures in general accordance with the Unified Soil

Classification System (ASTM D-2488). The resulting soil descriptions are shown on the soil boring profiles presented on Figures 3 and 4.

GENERAL SUBSURFACE CONDITIONS

General Soil Profile

The results of the field exploration and laboratory programs are graphically summarized on the soil boring profiles presented on Figures 3 and 4. The stratification of the boring profiles represents our interpretation of the field boring logs and the results of laboratory examinations of the recovered samples. The stratification lines represent the approximate boundary between soil types. The actual transitions may be more gradual than implied.

File No. 24-23-5253 -4-

The results of the borings indicate the following general soil profile:

Depth Below Ground Surface

(feet) Description

(Unified Soil Classification) From To

0 4.5 Fine sand (SP), fine sand with silt (SP-SM), silty fine sand

(SM), and clayey fine sand (SC)

4.5 12.5 Very loose to medium dense fine sand (SP) and fine sand with silt (SP-SM)

12.5 15 Very loose to loose fine sand with silt (SP-SM) and silty fine sand (SM)

The above soil profile is outlined in general terms only. Please refer to Figures 3 and 4 for soil profile details.

The results of the hand probes performed within the existing drainage ditch are presented in the table below.

Hand Probe Location Approximate Water

Depth (Feet)

Approximate Depth of

Soft Sediment (Inches)

Center of Ditch - East Side of Culvert near Boring TH-1

<1 10

Center of Ditch - West Side of Culvert near Boring TH-1

<1 13

Center of Ditch - East Side of Culvert near Boring TH-2

<1 13

Center of Ditch - West Side of Culvert near Boring TH-2

<1 8

Center of Ditch - East Side of Culvert near Boring TH-3

<1 2

Center of Ditch - West Side of Culvert near Boring TH-3

<1 18

Groundwater Level

The groundwater level was measured in the boreholes during drilling. As shown on Figure 4, groundwater was encountered at depths that ranged from approximately 5 to 5.3 feet below the existing ground surface on the date indicated. Fluctuation in groundwater levels should be anticipated throughout the year primarily due to seasonal variations in rainfall and other factors that may vary from the time the borings were conducted.

File No. 24-23-5253 -5-

ENGINEERING EVALUATION AND RECOMMENDATIONS

General

The results of our exploration indicate that, with proper site preparation as recommended in this report, the existing soils are suitable for supporting the proposed culvert structures.

The following are our recommendations for overall site preparation which we feel are best suited for the proposed structures and existing soil conditions. The recommendations are made as a guide for the design engineer, parts of which should be incorporated into the project's specifications.

Stripping of the Ditch Banks and Bottom

The banks and bottom of the existing ditch at the proposed culvert locations should be stripped and cleaned of all surface vegetation, stumps, debris, organic topsoil, muck, soft sediment, loose soils, or other deleterious materials, as encountered. The extent of stripping and clearing must be determined by visual observation, probing, and judgment during the earthwork operation. The means and methods should be the responsibility of the Contractor but must provide complete removal of the deleterious materials and protection of the exposed areas from erosion and prevent sloughing of the ditch banks.

We note that the stripping and bottom clearing operations will require removing materials, including vegetation, that has historically sloughed into the ditch bottom. Some of the vegetation that was formerly on the ditch banks may have become entrapped within and/or beneath the sloughed soils. Additionally, soft sediment and/or muck that were present in the ditch bottom before the sloughing may also be present beneath the sloughed materials. These materials must be excavated and removed in their entirety prior to placement of any fill and should be disposed of as directed in the project plans. The excavated unsuitable materials must not be used as fill or backfill material.

The contractor needs to exercise strict control during excavation and stockpiling to prevent mixing with the unsuitable materials. Sloughed soils that inadvertently become mixed with the unsuitable materials need to be stockpiled with the unsuitable materials in order to prevent them from being reused as fill. The stripping of the ditch banks and ditch bottom clearing operations should be monitored continuously by a representative of the project geotechnical engineer to verify that all unsuitable materials are removed, and the integrity of the banks are maintained prior to placement of fill materials. The Contractor shall determine limits of all unsuitable materials and ensure that they are removed from the project limits. The control of groundwater and the water in the ditch will be required to conduct these activities "in-the-dry" to the extent possible. Means and methods of dewatering and excavation, as well as slope protection and/or bracing are the responsibility of the Contractor. Additionally, all excavations should be sloped and/or braced to meet the

File No. 24-23-5253 -6-requirements of the Occupational Health and Safety Administration (OSHA) latest Standards.

Positive site drainage and other measures to protect the stripped surface of the ditch banks from erosion should be established early and maintained during construction.

Excavation

Based on the soil conditions encountered during the field exploration, we anticipate that the soils encountered in the borings drilled at the project site can be excavated with standard earth moving equipment, (i.e., front-end loaders and backhoes).

The soils below the bottom of the excavations should not be disturbed by the excavation process.

If soils become disturbed and difficult to compact below the bottom of the initial excavations, they should be over excavated to a depth necessary to remove all disturbed soils. Over excavated areas should be replaced with compacted backfill meeting the “Suitable Backfill Criteria” presented in a following section of this report.

The excavations should be safely braced to prevent injury to personnel or damage to equipment.

Temporary safe slopes should be cut at a minimum in accordance with OSHA, 29 CFR Part 1926

Final Rule, Excavation Requirements. Flatter slopes should be used if deemed necessary.

Surcharge loads should be kept at least 5 feet from excavations and spoil banks adjacent to excavations should be sloped no steeper than 2.0H to 1.0V. Provisions for maintaining workman safety within excavations is the sole responsibility of the Contractor.

Excavation and backfilling should be performed “in the dry”. Therefore, dewatering will likely be necessary to lower the groundwater level 2 to 3 feet below the bottom of the excavation and compaction surfaces. Dewatering of the excavations is discussed in a subsequent section of this report.

Proof Compacting

We recommend proof-compacting the bottom of the structure excavations to locate any unforeseen soft areas or unsuitable surface or near-surface soils, to increase the density of the upper soils, and to prepare the existing surface for the addition of the structure, backfill soils, etc.

(as required). Proof-compacting of the structure area should consist of at least three passes of a compactor capable of achieving the density requirements described in the next paragraph. Each pass should overlap the preceding pass by 30 percent to achieve complete coverage. If deemed necessary, in areas that continue to "yield", remove all deleterious material and replace with clean, compacted sand backfill. The proof-compacting should occur after cutting and before filling.

A density equivalent to or greater than 95 percent of the modified Proctor (ASTM D-1557) maximum dry density value for a depth of 1 foot in the structure areas must be achieved beneath the bottom of the structure excavations. Additional passes and/or overexcavation and

File No. 24-23-5253 -7-recompaction may be required if this minimum density requirement is not achieved. The soil moisture should be adjusted as necessary during compaction.

Suitable Backfill Material and Compaction of Backfill Soils

All backfill materials should be free of organic materials, such as roots and vegetation. We recommend using backfill with less than 12 percent by dry weight of material passing the U.S.

Standard No. 200 sieve size. The fine sand and fine sand with silt (Soil Strata Nos. 1 and 2 without roots, as shown on Figures 3 and 4) are suitable for use as backfill materials and, with proper moisture control, should densify using conventional compaction methods. Soils with more than 12 percent passing the No. 200 sieve can be used in some applications, but will be more difficult to compact due to their inherent nature to retain soil moisture.

All structural fill should be placed in level lifts not to exceed 12 inches in uncompacted thickness.

Each lift should be compacted to at least 95 percent of the modified Proctor (ASTM D-1557) maximum dry density value. The filling and compaction operations should continue in lifts until the desired elevation(s) is achieved. If hand-held compaction equipment is used, the lift thickness should be reduced to no more than 6 inches.

Dewatering

Based on the groundwater conditions encountered, the control of the groundwater may be required to achieve the necessary stripping and subsequent construction, backfilling, and compaction requirements presented in the preceding sections. The requirement for control of groundwater should particularly be anticipated for structure and utility excavations.

The actual method(s) of dewatering should be determined by the contractor. However, regardless of the method(s) used, we suggest drawing down the water table sufficiently, say 2 to 3 feet, below the bottom of any excavation or compaction surface to preclude "pumping" and/or compaction-related problems with the foundation soils. The dewatering should be performed in advance of any excavation to minimize soil disturbance caused by water seeping into the excavation.

QUALITY ASSURANCE

We recommend establishing a comprehensive quality assurance program to verify that all site preparation and foundation construction is conducted in accordance with the appropriate plans and specifications. Materials testing and inspection services should be provided by Ardaman &

Associates.

As a minimum, an on-site engineering technician should monitor all stripping to verify that deleterious materials have been removed and should observe the proof-compacting operation to verify that the appropriate number of passes are applied to the subgrade. In-situ density tests

File No. 24-23-5253 -8-should be conducted during backfilling activities and below the structures to verify that the required densities have been achieved. In-situ density values should be compared to laboratory

Proctor moisture-density results for each of the different natural and backfill soils encountered.

Finally, we recommend inspecting and testing the construction materials for the foundations and other structural components.

CLOSURE

The analyses and recommendations submitted herein are based on the data obtained from the soil borings presented on Figures 2 through 4. This report does not reflect any variations which may occur adjacent to or between the borings. The nature and extent of the variations between the borings may not become evident until during construction. If variations then appear evident, it will be necessary to re-evaluate the recommendations presented in this report after performing on-site observations during the construction period and noting the characteristics of the variations.

In the event any changes occur in the design, nature, or location of the proposed structures, we should review the applicability of recommendations in this report. Because of Ardaman &

Associates’ familiarity with this site and the proposed construction gained through performing the subsurface exploration and geotechnical engineering evaluation as presented in this report, Ardaman & Associates is best suited to provide monitoring and testing services during earthwork, and to provide continued evaluation and guidance during construction should variations in the soil conditions be encountered. This study does not include an evaluation of the environmental

(ecological or hazardous/toxic material related) condition of the site and subsurface.

This report has been prepared for the exclusive use of DRMP, Inc. in accordance with generally accepted geotechnical engineering practices for the purpose of the Lake Drive Culvert

Improvements project. No other warranty, expressed or implied, is made.

File No. 24-23-5253 -9-

We are pleased to be of assistance to you on this phase of the project. When we may be of further service to you or should you have any questions, please contact us.

Very truly yours, ARDAMAN & ASSOCIATES, INC.

Florida Registry 5950

Janie C. Ross Jason P. Manning, P.E.

Assistant Project Engineer Branch Manager

Florida License No. 53265

JCR/JPM/dk

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SUBSURFACE EXPLORATION

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CULVERT IMPROVEMENTS

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COCOA, FLORIDA

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TOWNSHIP 24 SOUTH

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RANGE 36 EAST

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SECTION 30

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OBTAINED FROM U.S.G.S. QUAD MAP: LAKE POINSETT, FLORIDA

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APPENDIX

Standard Penetration Test Procedures

STANDARD PENETRATION TEST

The standard penetration test is a widely accepted test method of in situ testing of soils (ASTM D

1586), and Ardaman & Associates generally follows this test method. A 2-foot long, 2-inch O.D.

split-barrel sampler attached to the end of a string of drilling rods is driven 18 or 24 inches into the ground by successive blows of a 140-pound hammer freely dropping 30 inches. The number of blows needed for each 6 inches of penetration is recorded. The sum of the blows required for penetration of the second and third 6-inch increments of penetration constitutes the test result or

N-value. After the test, the sampler is extracted from the ground and opened to allow visual examination and classification of the retained soil sample. The N-value has been empirically correlated with various soil properties.

The tests are usually performed at 5-foot intervals. The test holes are advanced to the test elevations by rotary drilling with a cutting bit, using circulating fluid to remove the cuttings and hold the fine grains in suspension. The circulating fluid, which is a bentonitic drilling mud, is also used to keep the hole open below the water table by maintaining an excess hydrostatic pressure inside the hole. In some soil deposits, particularly highly pervious ones, flush-coupled casing must be driven to just above the testing depth to keep the hole open and/or prevent the loss of circulating fluid.

Representative split-spoon samples from the soils are brought to our laboratory in air-tight jars for further evaluation and testing, if necessary.