Appendix_6.pdf

Attachment 1: Geotechnical Report

Geotechnical Engineering Report Gulf Beach Booster Station, St Pete Beach, Florida

Prepared for:

Wright-Pierce

Prepared by:

MADRID ENGINEERING GROUP, INC., dba MADRID CPWG

2030 State Road 60 East Bartow, FL 33830

863-533-9007

Project No. 14989 August 2022

Madrid CPWG

MADRID CPWG

2030 State Road 60 E Ph: (863) 533-9007 Bartow FL 33830-4268 Fax: (863) 533-8997

AT THE READY www.madridcpwg.com

August 01, 2022

Wright Pierce 601 South Lake Destiny Rd, Suite 290 Maitland, FL 32751 Attn: Christopher Baggett

Re: Madrid Project No. 14989 Geotechnical Engineering Report Gulf Beach Booster Station St Pete Beach, Florida

Dear Mr. Baggett:

Madrid Engineering Group, Inc., dba Madrid CPWG, (Madrid) is pleased to submit this Geotechnical Engineering Report summarizing the results of our geotechnical subsurface exploration and engineering evaluation services completed for the above referenced project. The work was completed in general accordance with the authorized scope of work in our cost estimate proposal dated October 28, 2021 and provides general geotechnical recommendations regarding the proposed design and construction.

We appreciate the opportunity to be of service to you on this project and look forward to working with you on future projects. If you have any questions, please do not hesitate to contact us.

Sincerely, Madrid Engineering Group, Inc. (EB 6509)

08/01/2022 Debashis Sikdar, P.E.

Senior Geotechnical Engineer Florida P.E. No. 94427

Attachment: Geotechnical Engineering Report

Gulf Beach Booster Station Geotechnical Report Wright-Pierce Madrid Project No. 14989 August 2022

EXECUTIVE SUMMARY

Project Description

Project Features Relative to This Report

Primary Structures

The existing booster station building is proposed to be expanded at the south end

Pipelines On-site vaults and pipeline leading to the booster station are to be replaced

Stormwater A swale system for stormwater control is proposed to the northeast of the building

Field Activities

• Two (2) Standard Penetration Test (SPT) borings (B-1 and B-2) to a depth of 55 feet below ground surface (bgs) within the proposed building expansion footprint

• One (1) SPT borings (B-4) to a depth of 30 feet bgs within the proposed generator pad

• Two (2) SPT borings (B-3 and B-5) to a depth of 10 feet bgs within the proposed vaults and pipeline replacement areas

• One (1) shallow test pit (TP-1) with supplemental hand auger in proposed stormwater swale location

Findings and Recommendations

Based on the results of the exploration completed at the site and our professional opinion, the existing site is suitable for the support of the proposed structures on a shallow foundation provided our recommendations are implemented. Shallow soils are mostly loose to medium dense sands with clayey sand and soft silt and clay. Proof-rolling and foundation preparation/compaction will be a critical site preparation activity in order to provide uniform foundation performance. Foundation sizing is also critical to bearing capacity and settlement, as discussed subsequently. Settlement is anticipated to be less than 1 inch with less than ½ inch differential provided our recommendations are implemented and nearly all settlement should be immediate (occurring during construction). Some minor long-term settlement is anticipated due to clayey soils at the deeper depth and specific foundation recommendations are provided below. Organic soils do not appear to be a problem for the proposed construction, assuming any topsoil and roots are removed.

The water table is shallow at this site (as shallow as 48 inches during the soil borings) and additional fill would be beneficial for improved bearing capacity of foundations and/or improved performance of pavement sections. A confining layer of highly plastic clay / silt, clayey sand was encountered at approximately 37 feet depth below ground surface. The water table depth was 4 feet bgs and we estimate the SHWT generally to be approximately about 2 feet bgs.

TABLE OF CONTENTS

1.0 INTRODUCTION AND PROJECT DESCRIPTION

1.1 General

1.2 Site Location and Description

1.3 Soil Survey Review

2.0 FIELD EXPLORATION

2.1 Test Pits and Undisturbed Sample Collection

2.2 Standard Penetration Test Borings

3.0 SUBSURFACE CONDITIONS AND LABORATORY TESTING

3.1 Subsurface Soil Conditions

3.2 Groundwater Conditions and Seasonal High Ground Water

3.3 Laboratory Testing

4.0 EVALUATION AND GENERAL RECOMMENDATIONS

4.1 General Considerations

4.2 Foundation Analysis and Evaluation

4.3 Modulus of Subgrade Reaction

4.4 Deep Foundation Assessment

4.4.1 Axial Capacity

4.4.2 Pile Group Effect

4.4.3 Precast Prestressed Concrete Pile Installation and Monitoring

4.5 Site Preparation and Earthwork

4.5.1 Clearing and Stripping

4.5.2 Proof-Rolling

4.5.3 Earthwork and Compaction

4.5.4 Excavation and Shoring

4.5.5 Dewatering

4.5.6 Pipe Bedding and Backfilling

4.5.7 Unsuitable Materials

4.6 Stormwater Ponds

4.7 Shallow Excavations and Dewatering

4.8 On-Site Soil Suitability

4.9 Quality Assurance

5.0 LIMITATIONS

FIGURES

Figure 1 Site Location Map Figure 2 USGS Topographic Map Figure 3 NRCS/USDA Soil Map Figure 4 Boring Location Plan

APPENDICES

Appendix A Soil Boring Logs Appendix B Laboratory Test Results Appendix C Bearing Capacity vs Settlement Graph Precast Piles Charts (Depth vs. Capacity)

1.0 INTRODUCTION AND PROJECT DESCRIPTION

1.1 General

Madrid Engineering Group, Inc., dba Madrid CPWG, (Madrid) is pleased to submit this report summarizing the results from our subsurface soil exploration, consistent with the instructions provided by Wright-Pierce (Designer), and geotechnical engineering evaluation for the proposed improvements including expansion of the existing building, replacement of vaults and pipelines, and a swale system for stormwater control at the Gulf Beach Booster Station in St Pete Beach, Florida. Our conclusions and recommendations are based on the results of our field exploration, laboratory testing, and appropriate engineering analyses.

Madrid understands the following regarding the specific features:

Table 1.1

Project Features Relative to This Report

Primary Structures

The existing booster station building is proposed to be expanded at the south end

Pipelines On-site vaults and pipeline leading to the booster station are to be replaced

Stormwater A swale system for stormwater control is proposed to the northeast of the building

The purpose of this exploration was to collect subsurface soil and groundwater information to provide an evaluation of the existing subsurface conditions at the boring locations (within the footprint for the proposed expansion, pipelines, and stormwater system) and to identify constraints or limitations (to the extent possible) that the subsurface conditions may impose on the planned construction. Loading information for the proposed structures was not provided to Madrid for this investigation; however, a preliminary site plan was provided, and this plan was used to locate the soil borings.

The scope of work for this investigation included review of existing geological data, a field exploration and laboratory testing program, evaluation of soil testing results, evaluating site suitability and providing general geotechnical recommendations for construction, including providing shallow foundation recommendations.

1.2 Site Location and Description

The subject site is located at the northeast corner of the intersection between 45th Ave and Gulf Blvd in St Pete Beach, Florida as shown on Figure 1, Site Location Map.

Specifically, the property is located in Section 6 and 7, Township 32 South, Range 16

East in Pinellas County, Florida. The proposed site consists of the green areas surrounding the active booster station.

The site is generally flat and level with elevation obtained from Google Earth at the boring locations at approximately 4 feet. GIS topographic information is provided on Figure 2, USGS Topographic Map. Boring/test elevations provided in this report were estimated based on Google Earth data; no surveying was completed by Madrid.

1.3 Soil Survey Review

The Natural Resources Conservation Services (NRCS) Soil Survey reports provide a general description of the typical shallow soil strata (about 6 feet) encountered within each particular soil mapping unit and reports typical depth to seasonal high water levels.

The NRCS defines seasonal high water as “a zone of saturation at the highest average depth during the wettest season that is at least six inches thick, persists for more than a few weeks, and is within six feet of the soil surface.” The Soil Survey for Polk County indicates shallow soils at the site are comprised of Palm Beach fine sand, 0 to 8 percent slopes (map unit 19), as shown on Figure 3, NRCS/USDA Soil Map and summarized below.

According to the NRCS, Palm Beach fine sand consists of excessively drained fine sand formed on ridges on marine terraces. Typically, it consists of dark grayish brown fine sand at the surface to 4 inches below ground surface, followed by light gray fine sand to 80 inches mixed with 15 to 35 percent shell fragments by volume. Permeability is very rapid and the available water capacity is very low. The seasonal high water table is not encountered within six feet of the ground surface.

2.0 FIELD EXPLORATION

2.1 Test Pits and Undisturbed Sample Collection

Madrid completed one test pit (TP-1) within the footprint of the proposed stormwater swale site to a depth of approximately 2 feet below ground surface (bgs). The test pit was performed in order to look for historical indicators of seasonal high groundwater levels at the proposed pond and to collect relatively undisturbed samples (Shelby tubes), one vertical and one horizontal at the base of the test pit, for laboratory permeability testing. The test pit was supplemented with a hand auger boring at the base of the test pit to a depth of 7 feet bgs. In addition to classifying the encountered soils using the Unified Soil Classification System (USCS), the soil colors using the Munsell Color Chart were also described. The test pit logs are combined with the hand auger logs, which are provided with the boring logs in Appendix A.

2.2 Standard Penetration Test Borings

On July 11, 2022, Madrid explored subsurface conditions at the site by drilling five

(5) Standard Penetration Test (SPT) borings (B-1 through B-5) with track mounted drilling equipment to depths ranging from 10 to 55 feet below ground surface (bgs). A GPS hand unit (typical accuracy of +/- 10 feet) was utilized in the field for location purposes. Boring locations are shown at the bottom of the boring logs in Appendix A. The boring locations are plotted on Figure 4, Boring Location Plan and should be considered approximate.

The following borings were completed:

Table 2.2

SPT Borings

Primary Structures

Two SPT borings to 55’ bgs designated B-1 and B-2 at proposed building expansion footprint. Includes B-4 to 30’ bgs at the proposed generator pad.

Pipeline Two SPT borings to 10’ bgs designated B-3 and B-5 at proposed vaults and pipeline replacement areas.

Stormwater One Test Pit and supplemental Hand Auger to 7’ bgs, designated TP- 1 at the swale site.

Disturbed samples from the SPT borings were obtained using a split-spoon sampler in general accordance with ASTM Specification D 1586, using a 1.4-inch I.D.

split-spoon sampler driven with a 140-pound auto hammer falling a distance of 30 inches.

An engineering technician familiar with soil classification and field evaluations logged the borings in the field and placed samples in sealed containers and returned them to Madrid’s laboratory for further classification. Upon completion, the boreholes were backfilled in general accordance with industry standards. The soil boring logs have been included with this report in Appendix A. Soil samples will be retained for a period of 3 months unless otherwise notified.

3.0 SUBSURFACE CONDITIONS AND LABORATORY TESTING

3.1 Subsurface Soil Conditions

In general, the SPT borings for the main structure and generator (B-1, B-2, and B-

4) encountered variable conditions that included a thick layer of loose to very dense sand (SP) down to approximately 37 feet bgs, followed by interbedded layers of silty sand (SM), clayey sand (SC), clay (CL), and high plasticity silt (MH) to 52 feet bgs. Borings B-1 and B-2 also encountered layers of highly organic material from about 47 feet bgs to end of boring at 55 feet bgs.

At the vaults and pipes replacement areas, borings B-3 and B-5 encountered very loose to dense sand (SP) down to end of borings at 10 feet bgs.

At the stormwater swale area (TP-1), the borings generally found interbedded layers of sand (SP) and slightly silty sand (SP-SM) to 6 feet bgs.

Table 3.1: Soil Types Encountered Stratum Number Typical Soil Description USCS

Classification

1 Fine Sand to Fine Sand with trace Silt and/or Clay SP

2 Fine Slightly Silty Sand or Fine Slightly Clayey Sand SP-SM, SP-SC

3 Silty Sand or Clayey Sand SM, SC

4 Highly Plastic Silt MH

5 Clay CL

6 Organic Silt OL

No losses of drilling fluid circulation were reported in any of the SPT borings. The general soil profiles described above and as presented on the boring logs are based on our interpretation of subsurface conditions encountered at the boring locations only.

Boundaries between soil layers are approximate and for illustration purposes only.

Variations in soil conditions in both horizontal and vertical directions different from those presented are likely to exist between boring locations.

3.2 Groundwater Conditions and Seasonal High Ground Water

The project site is relatively flat and level. We note that the water table was encountered in the SPT borings at depths ranging from 4 to 4.5 feet bgs. Seasonal fluctuations in the groundwater level should be anticipated due to variations in rainfall.

The Soil Survey for Pinellas County, Florida describes the seasonal high water table (SHWT) for the map unit to be greater than 72 inches from the surface. However, due to the low site elevation and its immediate proximity to the beach, we find the encountered water table to be consistent with expectations for the site. Based upon the published survey information and our findings during the exploration, Madrid recommends a design high water table level at 2 feet bgs.

3.3 Laboratory Testing

Laboratory tests for natural water content (ASTM D2216), percent passing the No.

200 sieve (ASTM D1140), organic content (ASTM D2974), and Atterberg Limits Determination (ASTM D4318), as well as constant head permeability testing (AASHTO T215), were performed on selected samples retrieved during the field exploration from the SPT borings, Test Pit, and Hand Auger to verify the visual and tactile soil classifications. Laboratory test reports are included in Appendix B.

Table 3.3a

Lab Summary

<#200 Sieve 1.7% - 81.1%

% Moisture 4.6% - 99.8%

Atterberg Limits LL=59, PI=15

% Organic 4.3% - 19.9%

• During the field visit, Madrid obtained a set of undisturbed soil samples for laboratory permeability analysis. These samples were collected from within the excavated test pit (at TP-1), at the location shown on Figure 4. Vertical samples were obtained from a depth of about 24 to 30 inches bgs, and horizontal samples were obtained at a depth of about 24 inches bgs. The results of the laboratory permeability testing and percent passing the No. 200 sieve are summarized in the Table 4.6. These are ultimate values, and the appropriate factor of safety should be applied. Detailed Constant Head Permeability Reports have been included with this report in Appendix B.

4.0 EVALUATION AND GENERAL RECOMMENDATIONS

4.1 General Considerations

The following conclusions and recommendations are based on our understanding of the proposed project, the data obtained from the field exploration, experience with similar conditions, and generally accepted principles and practices of geotechnical engineering. Based on the results of the exploration completed at the site and our professional opinion, the existing site is suitable for the support of the proposed structures on a shallow foundation provided our recommendations are implemented. Soil conditions include very loose to medium dense sand to clayey sand. Loose soils were present near the ground surface. Proof-rolling and foundation preparation/compaction will be a critical site preparation activity in order to provide uniform foundation performance. Foundation sizing is also critical to bearing capacity and settlement, as discussed subsequently.

Some minor long-term settlement is anticipated due to clayey soils in the deeper depth and specific foundation recommendations are provided below. Organic soils do not appear to be a problem for the proposed construction, assuming any topsoil and roots/stumps are removed.

The water table is shallow at this site (as shallow as 48 inches during the soil borings) and additional fill would be beneficial for improved bearing capacity of foundations and/or improved performance of pavement sections. The water table depth is at about 4 feet bgs and we estimate the SHWT ranges between about 2 feet bgs.

Permeability in the sandy soil at TP-1 was about 6.7 in/hr (Vert.) and 9.3 in/hr (Hor.). A confining layer was encountered at depths ranging from about 37 to 55 feet bgs. Our analysis and evaluation assume all recommendations are implemented during construction.

4.2 Foundation Analysis and Evaluation

The soils at this site consist primarily of loose to medium dense sand (SP) and clayey sand (SC). Soil compaction effort will be very important for improved long-term foundation performance. Compaction of the existing soil should be completed before any filling activities, in accordance with procedures described subsequently. Some over-excavation and replacement with the same material in a compacted effort is likely required.

Bearing Capacity Structure loading information was not provided to Madrid for the main building.

Settlement analysis was performed for shallow, continuous (strip) footings and square spread footings. Shallow foundations for the building should be embedded at least 18 inches below final grade and should be sized according to the charts provided in Appendix C, which includes embedment options at 1.5-, and 2.0-feet depth below final grade with footing widths from 1.5 feet to 3 feet for strip footings; and 3 feet to 6 feet for spread footing. Any foundation size and loading conditions that are at or below the corresponding solid color line are acceptable from a bearing capacity standpoint. (safety factor of 3 against bearing capacity failure).

Settlement Provided the soil below structure foundations is prepared as per our recommendations in Section 4.5 and loading does not exceed those provided herein, total settlement should be less than 1 inch with less than 1/2-inch differential settlement.

Most of the settlement should occur immediately (during construction) as the soils at this site are very sandy and the clayey soils are relatively deep. Settlement estimates should be considered very approximate and will vary across the site. As previously stated, we suggest that the structural engineer (foundation designer) consider additional reinforcement to minimize future cracking associated with differential foundation movement.

It should be noted that given the high variability of subsurface conditions, limited field and laboratory data, and limitations of the numerical model, settlement predictions developed by Madrid are approximate. Actual settlements observed during loading will depend on variations in subsurface conditions. When the stress zones for individual isolated footings overlap, the bearing pressure from the two footings is increased greater than the individual pressures. This should be considered by the design engineer.

4.3 Modulus of Subgrade Reaction

Reinforced concrete ground floor slabs are typically designed utilizing the modulus of subgrade reaction (k). For the design of slabs subject to sustained loads of up to 150 psf, a long-term modulus of subgrade reaction of 100 pounds per cubic inch (pci) is recommended. For short-term transient loads such as traffic or wheel loads, slabs, or pavements may be designed considering a subgrade reaction modulus of 150 pci. These values are based on estimated storage loadings, current grade levels, flexible floor slabs, and implementation of the site preparation recommendations provided herein. If higher modulus values are required, Madrid should be contacted for further evaluations.

4.4 Deep Foundation Assessment

Building will likely be supported on deep foundation. Based on our experience with foundation support of these structures constructed in the vicinity of the current building location, we have performed analysis for 12-in and 14-in precast, prestressed concrete pile (PPCP). If additional pile sizes or types are to be considered or greater foundation loads are anticipated, Madrid should be contacted for additional analyses and recommendations.

4.4.1 Axial Capacity

Our analytical approach to pile capacity computations uses a static pile capacity equation to determine the ultimate pile capacity at a given penetration depth. The pile’s ultimate compression capacity is the sum of the pile shaft (skin friction) bearing and pile end (point) bearing. Coefficients of soil-pile interaction and end bearing (shallow local shear) were developed based on a soil model created from the field and laboratory test programs and experience with local soil materials. Other factors considered during pile capacity analyses include method of pile placement, type of pile, and pile installation equipment (when known).

Pile capacity analyses are in general accordance with guidelines from the Department of the Navy, Naval Facilities Engineering Command (NAVFAC) Design Manual 7.02. Pile capacity analyses considered 12-inch and 14-inch precast concrete piles.

The pile capacity curves for each pile size are included in Appendix C. The recommended ultimate pile design capacities do not include a factor of safety. If static pile load testing is performed, a factor of safety of 2.0 should be applied to come up with allowable pile capacity at respective depths; 2.5 can be used for dynamic load testing. If pile load testing is not performed, a factor of safety of 3.0 should be applied to estimate the allowable pile capacity at respective depths. Pile size and design tip elevation selection should be determined by the project structural engineer based on available geotechnical capacity and structural design requirements.

4.4.2 Pile Group Effect

Group effects were not considered during capacity computations or the development of the lateral design parameters above. Table 4.4.2 presents recommended efficiency reductions for various pile spacings.

Table 4.4.2 – Typical Pile Group Reduction Factors

Pile Spacing Axial Group Reduction Factor

Lateral Group Reduction Factor

2.5 pile diameters 3 pile diameters 4 pile diameters 5 pile diameters

+5 to 8 pile diameters

0.75 1.0 1.0 1.0 1.0

0.6 0.7 0.8 0.9 0.95

It should be noted that long-term pile settlement is dependent upon pile spacing and pile dead loads. Pile group settlement should be evaluated once pile spacing and loads have been determined.

4.4.3 Precast Prestressed Concrete Pile Installation and Monitoring

1. Selection of the foundation subcontractor should be based on qualifications, experience, past project production and documented schedule satisfactions, in addition to cost of services.

2. A dynamic pile load testing program should be implemented for driven piles with compression capacity requirements in lieu of static pile load tests. Dynamic testing should be performed in accordance with ASTM D-4945 procedures. Field data collection should use the Pile Driving Analyzer (PDA). CAPWAP analyses should be used to estimate total pile compression capacity. Driven pile drivability analyses should use the GRLWEAP method. The results of the PDA and CAPWAP analyses should be used to estimate tension capacities of the tested piles. Since the majority of the soil profile consists of sandy soils, pile setup is expected after initial pile driving; therefore, re-strike PDA tests should be planned for each test pile after a minimum setup time of 48 hours. Static lateral pile load tests, if deemed necessary by the project structural engineer, should be performed in accordance with ASTM D-3966.

3. All production piles should be installed in the same manner, to the same depth and with the same equipment utilized for the indicator and PDA testing program.

4. All piles shall be installed within three inches of the specified plan location, and shall be installed within 1% of vertical or batter alignment as determined at the leads.

5. The Madrid geotechnical engineer should be involved with the preparation of the driven piling specifications, indicator pile program, pile load test program, and all production pile installation activities. Madrid shall also be involved in the review/ acceptance process of the pile contractor submittals.

Experienced Madrid technical personnel should be involved with the field inspections of all test and production piles to result in full documentation for this phase of project construction.

4.5 Site Preparation and Earthwork

4.5.1 Clearing and Stripping

All construction areas should be cleared of any trees, scrub vegetation, existing debris and topsoil stripped as necessary to remove roots and other deleterious material.

Complete removal of stumps and roots is important to help reduce future settlement as any remnants decay in the future. Clearing and grubbing should be closely monitored by the Engineer. Topsoil is anticipated to be on the order of 6 inches or less and should be discarded or may be stockpiled for future reuse in landscape areas if desired. In addition, any abandoned utilities should be removed as open conduits can lead to soil erosion and a loss of support beneath foundations.

4.5.2 Proof-Rolling

After clearing and grubbing, the building pad, pavement areas and other foundation subgrade areas, including out to 10 feet horizontally from the plan limits, should be evaluated and methodically proof-rolled, as directed by representatives of Madrid, with compaction equipment or with heavy construction equipment (i.e. large vibratory smooth roller or loaded front-end loader) capable of achieving the required compaction. Rolling should continue until a density of at least 98 percent of Modified

Proctor maximum dry density (MPMDD) (ASTM D-1557) is achieved over the building pad, pavement areas and other foundation areas. Any soft, rolling or otherwise suspect areas should be investigated, and any unsuitable soils and/or unstable soil conditions should be removed and replaced with structural fill as described in Section 4.5.3.

4.5.3 Earthwork and Compaction

All structural soils (existing or placed) within 2 feet beneath the bottom of shallow foundations, pavement areas and floor slabs should meet gradation (no more than 12 percent fines or 4 percent organics) requirements and compacted to achieve the minimum density requirement of 98% of MPMDD. This may require excavation and compaction below footing subgrade level. Clayey sand soils at this site may not be suitable for re-use, depending on clay content. Organic content is not anticipated to be an issue provided topsoil is removed. Foundation subgrade soils should be inspected to verify that they meet the gradation and organic content requirements, compacted, and tested to verify in-place density to a depth of 24 inches below footing bottoms. The base of all excavations should be compacted to 98% of MPMDD prior to placement of fill.

Fill placement in large areas should be completed in lifts no greater than 12 inches in thickness and compacted to at least 98 percent of the MPMDD. If compaction cannot be achieved at 12-inch lifts, thinner lifts may be required. It is noted that heavy vibratory compaction near other structures has the potential to cause damage. Foundation soils in smaller footing excavations or utility trenches where compaction must be achieved with smaller hand operated equipment should be compacted in lifts no greater than 6 inches in thickness and compacted to at least 98 percent of the MPMDD.

Similar earthwork and compaction operations should be employed for utility installations. Generally, all utilities should be installed in accordance with the current addition of the Florida Department of Transportation Standard Specifications for Road and Bridge Construction. Prior to construction, bulk samples representative of anticipated subgrade and fill soils should be collected and subjected to Modified Proctor testing.

Existing clean sandy soils excavated from footings intended for reuse as backfill may require moisture conditioning to permit adequate compaction.

4.5.4 Excavation and Shoring

In general, the anticipated depth of trench excavations typically ranges from about

2 to 6 feet, but locally as deep as about 10 feet or more below existing grade at road crossings may be required. Trenches should be sufficiently wide to permit proper compaction along all sides of pipes and structures. The bases of trench excavations will expose loose sandy soil conditions at most locations along the pipeline route. Very soft or yielding subgrade soils should be excavated and replaced.

Braced or shored excavations may be required for space limitations using trench boxes or other stabilization methods. Excavation stability is the responsibility of the contractor. All excavations should conform to the Occupational Safety and Health Act (OSHA) requirements for Type C soils as described Federal Register 29 CFR Part 1926.

Excavated materials should not be stockpiled at the top of the slope within a horizontal distance equal to the excavation depth, unless specific provisions for surcharge loading have been included in the design of the shoring system.

Design of a shoring system is the responsibility of the selected contractor. A number of variable factors, such as nature and strength of excavated soils, depth of excavation and groundwater, proximity of adjacent structures, and economics of construction method, etc., will affect the choice of support method. All vertical shoring or prefabricated trench lining systems should be continuous and maintained in place to assure adequate temporary stability during backfilling of the pipe trench as recommended subsequently.

For design of below grade structures or shoring, the following general design parameters are recommended:

Table 4.5.4 – Lateral Earth Pressure Design Parameters

Depth, ft. Soil Type Unit Weight (sat./buoy, psf)

Phi Angle

Cohesion (psf)

Lateral Earth Pressure Parameters

Ko Kp Ka 0 to 4 Loose Sand 110 / 50 28 - - - 0.53 2.77 0.36

4 to 10 Medium Dense Sand 120 / 60 30 - - - 0.50 3.00 0.30

The earth pressure parameters in Table 4.5.4 do not include hydrostatic pressure.

We recommend that below grade retaining structures should consider water levels at potential flooded conditions and hydrostatic pressure be added for the soil layers located below the water table in addition to the lateral pressures mentioned in Table 4.5.4.

4.5.5 Dewatering

Groundwater was encountered in the boring locations at 4 feet during the time of drilling. Depending upon the depth of excavation and time of year when construction is scheduled, groundwater control may need to be taken into account by the contractors.

We recommend that, where necessary, a dewatering system be designed and installed to draw the groundwater table down to a minimum depth of two feet below the final excavated grade for pipelines. If needed, for excavations up to 10 feet depth, depending on the local soil profile present, a shallow well-point system may be adequate for trenches and small excavations up to approximately 50 feet in plan dimension.

Excavations in excess of 15 feet depth may require a multi-stage well-point system, deep wells or a single stage well-point installed from a reduced grade elevation to accomplish the recommended drawdown. Sump pumps may be effective, but only to locally dewater the soils; they may only be useful at very localized installations. The contractor should employ a registered professional engineer to design all shoring and dewatering systems.

4.5.6 Pipe Bedding and Backfilling

The following diagram indicates the typical pipe backfill limits and compaction requirements (6 or 12-inch lifts) that we recommend:

Clean fine sands (SP) containing less than five percent passing the U.S. standard

No. 200 sieve and less than four percent organic matter (as determined by ASTM D2974) may be used as select sand pipe bedding material. Most of the soils encountered along the pipeline route should meet this criterion. Import of fill should not be necessary for the pipeline backfill. Suitable pipe bedding should be free of stones, gravel, organics, vegetation and other deleterious material, placed in uniform loose lifts not exceeding six inches thick and compacted to at least 100 percent of its maximum dry density as determined by ASTM D698 (Standard Proctor-SPMDD). Bedding material within the middle 1/3 of the pipe diameter should be loosened for better seating of the pipe in the bedding soil and shaped to allow for bell joints if applicable. Pipe bedding material should be placed from one foot below to at least half-way up the pipe. Particular care needs to be exercised during pipe bedding placement and compaction around pipe haunches, elbows, and curves. Loose bedding materials may subsequently compact in-service, if subjected to dynamic or vibrational loading due to surge pressures, resulting in excessive pipe deflections and possibly failure. Soils in the cover zone (from half-way up the pipe to 1-foot over the pipe, as shown on the graphic above) should consist of clean to relatively clean sand (SP) or slightly silty sand (SP-SM) with no more than 12% silty fines passing the No. 200 sieve and less than 4% organic content, and also compacted to 100% of the SPMDD in lifts no greater than 6-inch compacted thickness. Compaction to

Top Zone

100% of the SPMDD should be performed at the base of all excavations prior to placing the first layer of backfill.

Excavation backfill material more than 1 foot above the pipe top zone should consist of granular soils with less than 15 percent fines content passing the No. 200 sieve and an organic content of not more than 4 percent generally conforming to USCS soil types SP to SP-SM/SP-SC and SM; use of Clayey Sand (SC) may present moisture conditioning problems and is not recommended. It appears that nearly all of the excavated soils will meet these requirements. Organic soils, if encountered, are not suitable backfill soils in any location and should be replaced with suitable fill. Excavation backfill typically should be placed in lifts no greater than 12 inches in compacted thickness and compacted to 100 percent of SPMDD. Common fill used more than 3 feet above the top of pipe and outside of structure or pavement areas can have up to 20% fines and be compacted to 90 percent of SPMDD unless under structures or roadways which must maintain a minimum compaction of 95% of SPMDD or as otherwise required for structure or roadway backfill requirements. Excavated spoil material intended for reuse as backfill will likely require moisture conditioning to permit adequate compaction.

4.5.7 Unsuitable Materials

In general, highly organic soils or clayey sand should not be re-used as backfill as it is generally difficult to compact and subject to long term settlement/decay.

Classification of soils as suitable for use as backfill should be monitored continuously during construction because the limited exploration performed for this study will not have identified all areas with unsuitable soils. We anticipate very few problems with unsuitable materials for this project, except for clayey sand encountered in the borings.

4.6 Stormwater Ponds

The following recommendations are provided for the design engineer to assist them with stormwater pond design. The borings within potential pond sites found sandy soil conditions found elsewhere at this site. A confining layer of clayey sand, silt and clay was encountered at depths of about 37 feet bgs. The following data was obtained for the pond locations:

Table 4.6: Pond Parameters

Pond Boring # Orientation

Percent Passing

# 200 Sieve

Average Permeability

(in/hr)

Water Table

Depth (in)

Estimated

SHWT

Depth (in)

Pond Bottom Elev. (ft)

Existing Ground Elev. (ft)

TP-1

Horizontal 2.5 9.3

54 24 -1 4 Vertical 3.0 6.7

Note: these values are ultimate values (no safety factor) and the designer should select conservative design values based on this information and their experience with similar conditions.

The shallow water table (design depth of 2 feet bgs) may be the most limiting factor for design purposes. Permeability rates were fast (6.7 in/hr vertical) and (about 9.3 in/hr horizontal), the designer should choose a conservative rate at pond for design purposes.

It was noted that horizontal permeability rates were slightly higher than vertical rates, which is typical for sandy soils in this part of Florida. The water table was encountered at a depth of 54 inches at the pond.

It is recommended that the pond designer select a conservative depth for the design SHWT. The designer should also note that the water table at this site appears to be relatively level and differences in groundwater depth are likely to be due to minor differences in ground surface elevation. Elevations reported on boring logs were estimated based on data from Google Earth and should be considered approximate only.

4.7 Shallow Excavations and Dewatering

Open-cut methods appear suitable for shallow excavations, but very loose sand may slough at shallow slopes. Temporary side slopes for the open-cut excavations should be stable in the short term at slopes of one and one-half feet horizontal to one foot vertical (1.5:1 H:V). All excavations should conform to the Occupational Safety and Health Act (OSHA) requirements for Type C soils as described Federal Register 29 CFR Part 1926. Design of a shoring system is the responsibility of the selected contractor. A number of variable factors, such as nature and strength of excavated soils, depth of excavation and groundwater, proximity of adjacent structures, and economics of construction method, etc., will affect the choice of support method.

All vertical shoring or prefabricated trench lining systems should be continuous and maintained in place to assure adequate temporary stability during backfilling of the trench as recommended subsequently. Excavated soils should not be stockpiled within 15 feet (horizontally) of the shored excavations, unless specific provisions for surcharge loading have been included in the design of the shoring system. The final decision on appropriate excavation methods and design of shoring systems is the responsibility of the contractor.

Based upon our recommended design water table (2 feet bgs) and depending upon the time of year, it appears that groundwater should be anticipated for excavations.

We recommend that a dewatering system be designed and installed to draw the groundwater table down to a depth sufficient to achieve compaction for the foundation;

this typically requires lowering the water to 2 to 3 feet below the foundation subgrade level. The contractor should employ a registered professional engineer to design all shoring and dewatering systems.

4.8 On-Site Soil Suitability

The soils encountered along the roadway alignment and within the proposed pond/potential borrow pit areas are generally suitable for use as embankment fill per FDOT Standard Plan Indices 120-1 and 120-2. These indices should be used to determine the specific usability of the soil types encountered during our exploration program. Select soils having an average organic content of more than 2.5 percent, or having an individual test value which exceeds 4 percent, shall not be used in the subgrade portion of the roadbed. Select soils having an average organic content of more than 5 percent, or an organic content individual test result which exceeds 7 percent, shall not be used in the portion of embankment inside a 1V:2H extending downward from the edge of the roadway shoulder. It is recommended that materials be compacted in place according to requirements detailed in this report.

4.9 Quality Assurance

We recommend implementing a comprehensive quality assurance program to verify that all site preparation and foundation construction is conducted in accordance with the recommendations herein and the appropriate plans and specifications. It is strongly recommended that Madrid be retained to perform materials testing and inspection services to observe that the subsurface conditions are as we have discussed herein and that foundation construction, ground densification and fill placement is in accordance with our recommendations. Madrid cannot accept responsibility for any conditions which deviate from those described in this report if not engaged to provide construction observation and testing for this project. An on-site engineering technician should monitor all site preparation to verify that all deleterious materials have been removed and should observe earthwork activities to verify that the foundation and pavement subgrade soils conform to the recommendations herein. In-situ density tests should be conducted during filling activities and below all footings, pavement areas and structure bottoms to verify that the required densities have been achieved. In-situ density values should be compared to laboratory Proctor moisture-density results for in-situ and fill soils to confirm they meet minimum compaction requirements.

5.0 LIMITATIONS

This report has been prepared for Wright-Pierce for the proposed improvements at the Gulf Beach Booster Station in St Pete Beach, Florida. The information in this report is intended for the sole use of the addressees and their assigns/agents and may not be relied upon or used by any third party without expressed written consent. The evaluations and recommendations presented herein are based on Madrid’s interpretation and understanding of site conditions and information provided by the Client. This report is not a specification document and is not intended for use as a part of the specifications.

Varying degrees of non-uniformity of the horizontal and vertical soil conditions may exist at the site. This study is not intended to be an evaluation of sinkhole risk. This study does not include an evaluation of the environmental (ecological or hazardous/toxic material related) condition of the site and subsurface. The study reported herein has been conducted in accordance with the generally accepted standards, principles and practices in the geotechnical engineering profession. No other warranty, expressed or implied, is made. Madrid is not responsible for the independent conclusions, opinions, and/or recommendations made by others based on the field investigation and laboratory testing data presented in this report. Soil samples will be stored at our Bartow Office for a period of 3 months from the date of this report unless other arrangements are made.

0 400

Feet

Wright-Pierce

MADRID CPWG

Sources: GIS Information (ESRI)

FIGURE 1

Site Location Map Gulf Beach Booster Station St Pete Beach, Florida

Drawn By: CJ Checked By: DeS Project Number:

Notes:

2030 State Road 60 East Bartow, Florida 33830 863 533-9007 Fax: 863 533-8997

EB-0006509

³

14989

Project Location

0 500

Feet

MADRID CPWG

Drawn By: CJ Checked By: DeS

Source: GIS Information (ESRI), Topographic Information (USGS)

2030 State Road 60 East Bartow, Florida 33830 863 533-9007 Fax: 863 533-8997

EB-0006509

³

Wright-Pierce

FIGURE 2

USGS Topographic Map Gulf Beach Booster Station St Pete Beach, Florida

Project Number:

14989

Project Location

100 19

0 500

Feet

MADRID CPWG

Drawn By: CJ Checked By: DeS

Source: GIS Information (ESRI), Topographic Information (USGS)

2030 State Road 60 East Bartow, Florida 33830 863 533-9007 Fax: 863 533-8997

EB-0006509

³

Wright-Pierce

FIGURE 3

NRCS/USDA Soils Map Gulf Beach Booster Station St Pete Beach, Florida

Project Number:

14989

Project Location

Legend

100, WATERS OF THE GULF OF MEXICO

16, MATLACHA

19, PALM BEACH

8, BEACHES

TP-1 (2')

B-1 (50')B-2 (50')

B-3 (10')

B-4 (30')

B-5 (10')

Drawn By: CJ Checked By: DeS

Project Number:

FIGURE 4

Boring Location Plan Gulf Beach Booster Station St Pete Beach, Florida

Wright-Pierce

14989

MADRID CPWG

2030 State Road 60 East Bartow, Florida 33830 863 533-9007 Fax: 863 533-8997

EB-0006509

Aerial Data Source – 2021 Microsoft Corporation, 2021 CNES Distribution Airbus DS.

G ulf Blvd

Notes: Base map provided by Client.

N

SCALE

(feet) 60

Legend

Test Pit LocationTP-1

SPT Boring LocationB-1

TP-1B-4

B-5B-3

B-2 B-1

APPENDIX A

Loose pale brown sand (SP)

With shells <#200 = 1.9%

Medium dense gray

Light gray

Dense

Medium dense gray

Soft gray highly plastic silt (MH) <#200 = 81.1%

LL = 59 PL = 44 PI = 15

Very soft clay (CL)

Loose dark gray with shells <#200 = 55.1% organic content = 4.3%

Loose light gray sand with shells (SP)

Loose pale brown sand (SP)

With shells <#200 = 1.9%

Medium dense gray

Light gray

Dense

Medium dense gray

Soft gray highly plastic silt (MH) <#200 = 81.1%

LL = 59 PL = 44 PI = 15

Very soft clay (CL)

Loose dark gray with shells <#200 = 55.1% organic content = 4.3%

Loose light gray sand with shells (SP)

3-4-4-5

3-2-3-4

5-10-12-15

2-4-7-11

1-11-12-17

2-16-18

14-16-21

10-10-12

6-6-7

2-3-9

WOR-WOR-

WOH-WOH-

1-2-4

4-4-3

REMARKS: Water table encountered at 48" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.71961°N, 82.73902°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

B-01 7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

WOH

Loose gray sand (SP)

Medium dense light gray with shells

<#200 = 2.2%

Very dense

Medium dense

Gray

Soft gray clayey sand (SC) <#200 = 34.7%

Very loose gray

Loose dark gray silty sand with shells (SM)

Very stiff very dark gray organic silt (OL) <#200 = 21.9% organic content = 19.9%

Loose gray sand (SP)

Medium dense light gray with shells

<#200 = 2.2%

Very dense

Medium dense

Gray

Soft gray clayey sand (SC) <#200 = 34.7%

Very loose gray

Loose dark gray silty sand with shells (SM)

Very stiff very dark gray organic silt (OL) <#200 = 21.9% organic content = 19.9%

2-2-4-6

6-6-6-7

8-8-4-3

5-5-6-10

2-5-13-17

3-7-7

15-19-23

8-6-6

6-6-7

3-5-4

WOH-WOH-

WOH-WOH-

WOH

WOH-1-2

4-5-8

REMARKS: Water table encountered at 48" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.71961°N, 82.73925°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

B-02 7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

Loose pale brown sand (SP)

With shells

Very loose very pale brown

Loose gray

Medium dense

Loose pale brown sand (SP)

With shells

Very loose very pale brown

Loose gray

Medium dense

2-4-3-3

3-3-3-3

1-1-1-1

3-1-2-2

3-6-4-5

REMARKS: Water table encountered at 48" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.72003°N, 82.73945°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

B-03 7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

Medium dense light gray sand (SP)

<#200 = 3.4%

Loose pale brown

Medium dense very pale brown

Dense light gray

Very pale brown

Medium dense light gray sand (SP)

<#200 = 3.4%

Loose pale brown

Medium dense very pale brown

Dense light gray

Very pale brown

3-5-7-8

7-5-6-10

4-4-3-6

2-2-2-4

4-6-8-10

1-12-17

6-14-20

4-8-20

13-15-11

REMARKS: Water table encountered at 48" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.72001°N, 82.73929°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

B-04 7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

Loose light gray sand (SP)

Medium dense gray

Loose

Pale brown

Dense light gray

Loose light gray sand (SP)

Medium dense gray

Loose

Pale brown

Dense light gray

3-4-4-4

4-5-7-6

4-4-2-2

1-2-1-5

10-13-16-28

REMARKS: Water table encountered at 48" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.72003°N, 82.73922°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

B-05 7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

Pale brown sand (SP)

<#200 = 1.7%

Dark gray slightly silty sand (SP-SM)

Gray sand (SP) Pale brown

Pale brown sand (SP)

<#200 = 1.7%

Dark gray slightly silty sand (SP-SM)

Gray sand (SP) Pale brown

REMARKS: Water table encountered at 54" bgs. No loss of circulation. Auto hammer used.

BORING NO.

BORING LOCATION: 27.72002°N, 82.73903°W

N-Value Elev.

(ft)

STANDARD PENETRATION

TEST

DESCRIPTIONDESCRIPTION

TP-01

7/11/2022 14989 Gulf Beach Booster Station

0 10 8060403020

DATE DRILLED

PROJECT NUMBER

PROJECT

TEST BORING RECORD

Madrid CPWG

Blows Depth

(ft) Depth

(ft)

M E

G W

IT

H

B

LO

W C

O U

N T

S T

O P

B

O R

IN

G

L O

G .G

P J

N E

W M

E G

T E

M P

LA

T

E .G

D T

/2

/2

APPENDIX B

2030 State Road 60 East Bartow, Florida 33830

(863)533-9007

Project Number: 14989 Project Name: Gulf Beach Booster Station

Project Location: Maitland, FL Date Tested:

Client: Wright-Pierce Tested By: BJN

B-1 2-4' 226 146.78 119.48 8.24 80.3% 24.5% 117.35 1.9% B-1 38.5-40' 204 95.25 60.96 8.18 60.6% 65.0% 18.15 81.1% B-1 48.5-50' 120 114.81 70.99 8.16 58.9% 69.7% 36.35 55.1% B-2 4-6' 135 112.19 96.33 8.20 84.7% 18.0% 94.37 2.2% B-2 38.5-40' 200 119.94 86.15 8.19 69.8% 43.3% 59.07 34.7% B-2 53.5-55' 224 102.51 55.43 8.24 50.1% 99.8% 45.09 21.9% B-4 2-4' 201 105.09 95.94 8.26…