Preliminary Report of Geotechnical Investigation -...

100% Report of Geotechnical Engineering Investigation for Structures

CENTRAL FLORIDA COMMUTER RAIL TRANSIT SUNRAIL PHASE 2 SOUTH

MP A811.3 Shingle Creek Bridge Financial Project No. 423446-9-52-01

GEC Project No. 2135G6

December 22, 2014 AECOM 300 Colonial Center Parkway, Suite 130 Lake Mary, Florida 32746 Attention: Mr. George Gault, P.E. Subject: 100% Report of Geotechnical Engineering Investigation for Structures

CENTRAL FLORIDA COMMUTER RAIL TRANSIT – SUNRAIL PHASE 2 SOUTH MP A811.3 Shingle Creek Bridge Financial Project No. 423446-9-52-01 GEC Project No. 2135G6

Dear Mr. Gault: Geotechnical and Environmental Consultants, Inc. (GEC) is pleased to present this 100% Report of Geotechnical Engineering Investigation for Structures for Phase 2 South of the Central Florida Commuter Rail Transit (CFCRT) SunRail project. The purpose of this investigation was to explore subsurface conditions at the MP A811.3 Shingle Creek bridge site, and to use the information obtained to develop geotechnical engineering recommendations to guide design and construction of the proposed rail improvements. This report describes our exploration procedures, exhibits the data obtained and presents our recommendations and conclusions regarding the geotechnical engineering aspects of this project. Geotechnical recommendations included in this report are subject to change as project plans develop. The results of our geotechnical investigation for the remainder of the CFRC Phase 2 South alignment improvements are submitted under separate cover. GEC appreciates the opportunity to be of service to AECOM and the FDOT on this project. If you should have any questions concerning the contents of this report, please contact us.

GEC Project No. 2135G6 ii 100% Report of Geotechnical Engineering Investigation for Structures

SunRail Phase 2 South: MP A811.3 Shingle Creek Bridge

Very truly yours, GEOTECHNICAL AND ENVIRONMENTAL CONSULTANTS, INC. 2510 Michigan Avenue, Suite D Kissimmee, Florida 34744 Certificate of Authorization No. 5882 Craig G. Ballock, P.E. Gary L. Kuhns, P.E. Senior Geotechnical Engineer President cc: Mr. Tharwat Hannadawod – FDOT Geotechnical Project Manager

GEC Project No. 2135G6 iii 100% Report of Geotechnical Engineering Investigation for Structures


Table of Contents 1.0 ALIGNMENT DESCRIPTION .............................................................................................. 1 2.0 REVIEW OF AVAILABLE DATA .......................................................................................... 2

2.1 NRCS Soil Survey .......................................................................................................... 2 2.2 USGS Quadrangle Map ................................................................................................. 3 2.3 USGS Potentiometric Map Data ................................................................................... 3 2.4 Regional Geology ......................................................................................................... 3

3.0 SUBSURFACE EXPLORATION ............................................................................................ 5

3.1 SPT Borings ................................................................................................................... 6 3.2 Machine Auger Borings ................................................................................................ 6 3.3 Groundwater Measurement ........................................................................................ 6

4.0 LABORATORY TESTING .................................................................................................... 6 5.0 SUBSURFACE CONDITIONS .............................................................................................. 8

5.1 Bridge Boring Results ................................................................................................... 8 5.2 Groundwater Levels ..................................................................................................... 9

6.0 ANALYSES AND RECOMMENDATIONS ........................................................................... 10

6.1 Foundation Design Alternatives ................................................................................. 10 6.2 Axial Load Analysis ..................................................................................................... 10 6.3 Downdrag Settlement Considerations ....................................................................... 12 6.4 Scour Resistance ........................................................................................................ 12

7.0 SINKHOLE RISK .............................................................................................................. 12 8.0 USE OF THIS REPORT ..................................................................................................... 14

GEC Project No. 2135G6 iv 100% Report of Geotechnical Engineering Investigation for Structures


APPENDIX Pile Data Table Davisson Pile Capacity vs. Pile Tip Elevation Graphs Figure 1: USGS Quadrangle Map Figure 2: NRCS Soil Survey Map Figures 3 – 8: Boring Location Plan and SPT Boring Results Table 6: Summary of Corrosion Series Test Results Table Table 7: Summary of D50 Test Results and Particle Size Distribution Curves Scour Resistance Calculations Sample FB Deep Analyses

GEC Project No. 2135G6 1 100% Report of Geotechnical Engineering Investigation for Structures


1.0 ALIGNMENT DESCRIPTION The Central Florida Commuter Rail Transit, or SunRail, Phase 2 South alignment begins at the Sand Lake Road Station in Orange County (MP A796.6) and extends southward along the former CSX railroad to its termination point at the Poinciana Station in Osceola County (MP A813.8), a distance of about 17.2 miles. The proposed improvements include the addition of approximately 13.5 miles of 2nd track, upgrades to approximately 4.1 miles of track siding, replacement of 7 bridges and 2 large culvert crossings, replacement/extension of 26 cross drains and the addition of linear ponds along the north and south sides of portions of the alignment for floodplain compensation.

This report addresses the proposed replacement of the MP A811.3 bridge structure over Shingle Creek. The existing bridge at MP A811.3 supports a single track section supported on timber piles. The Shingle Creek floodplain, consisting of wetlands and swamp areas, borders the project alignment to

the north and Old Tampa Highway, a two-lane, rural section roadway, parallels the project alignment to the south. The project site is shown on an excerpt of the USGS Quadrangle map on Figure 1 in the Appendix. A summary of the MP A811.3 bridge location, proposed replacement structure and the existing ground surface elevations (based on project DTM information at the boring locations) are summarized in the following table:

Table 1 Summary of Bridge Locations

Bridge Mile Post

No.

Existing Structure

Type

Replacement Structure

Type Section Township Range

Approx. Ground Surface

Elevation (ft NAVD88)

A811.3 Bridge: 370 ft. Timber Trestle Dual Bridges (11 Spans) 31 25 S 29 E +55 to +65

The results of our geotechnical investigation and recommendations for the remainder of the SunRail Phase 2 South alignment improvements are submitted under separate cover.

This report addresses the proposed replacement of the MP A811.3 bridge structure over Shingle Creek.



2.0 REVIEW OF AVAILABLE DATA To obtain general information on soil and groundwater conditions at the MP A811.3 bridge structure, GEC reviewed available data including USGS Quadrangle Maps, the Natural Resources Conservation Service (NRCS) Soil Survey of Osceola County and other published sources. A summary of this information is presented in the following report sections. 2.1 NRCS Soil Survey The United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey of Osceola County, Florida was reviewed to obtain near-surface soils and groundwater information along the project alignment in the area the MP A11.3 Bridge. An excerpt of the NRCS Soil Survey map showing the approximate project alignment and bridge location is presented on Figure 2 in the Appendix. The NRCS soils depicted in the vicinity of the MP A811.3 Bridge are summarized in the following table.

Table 2 NRCS Soil Survey Summary - Osceola County Florida

Unit No.

Soil Name Depth

(inches) Soil Description

Unified Classification

Symbol

Depth to Seasonal High Groundwater

(feet)

13 Gentry fine sand

0 – 24 24 – 64

64 – 80

Fine sand Fine sandy loam, sandy loam, sandy clay loam Fine sand, loamy fine sand, fine sandy loam

SM, SP, SP-SM SC, SC-SM, SM

SM, SP-SM

+2.0 – 0.0

In general, the soil unit listed above is classified as sands with varying amounts of silt fines (SP, SP-SM, SM, SM-SC, SC) and is generally appropriate for support of the proposed improvements. However, Gentry fine sand (Soil Unit 13) is typically associated with areas of poorly drained soils in shallow depressions, sloughs, drainage ways and swamps. The NRCS predicts seasonal high groundwater levels at the MP A811.3 bridge site to range from 2 feet above the natural ground surface at the natural ground surface. Information contained in the NRCS Soil Survey is very general and may be outdated. It may not, therefore, be reflective of actual soil and groundwater conditions, particularly if development in



the site vicinity has modified soil conditions or surface/subsurface drainage. The information obtained from the soil borings provides a better characterization of actual site subsurface conditions. 2.2 USGS Quadrangle Map Based on GEC’s review of the Kissimmee, Florida Quadrangle map, reproduced in Figure 1, and project topographic survey information, the existing ground surface elevations in the vicinity of the MP A811.3 bridge site range from approximately +55 to +65 feet NAVD. In addition, project topographic survey information indicates the Shingle Creek channel bottom elevation typically ranges from +53 to +56 feet NAVD. Based on our review of the Quadrangle map, the MP A811.3 bridge site vicinity can be classified as lowland topography and terrain associated with the Shingle Creek Floodplain. 2.3 USGS Potentiometric Map Data Based on our review of the September 2008 USGS Map, “Potentiometric Surface of The Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida,” the approximate potentiometric level of the Floridan aquifer at the MP A811.3 bridge site is +59 feet NGVD (+58.1 feet NAVD). Since the existing ground surface elevations in the project

vicinity range from approximately +53 to +65 feet NAVD, artesian flow conditions should be anticipated at the MP A811.3 bridge site in borings or wells that penetrate the clay confining layer. Artesian conditions were not encountered in our soil borings.

2.4 Regional Geology

Due to its prevalent geology, referred to as karst, Central Florida is prone to the formation of sinkholes, or large, circular depressions created by local subsidence of the ground surface. The nature and relationship of the three sedimentary layers typical of Central Florida geology cause sinkholes. The deepest, or basement, layer is a massive cavernous limestone formation known as the Floridan

…artesian flow conditions should be anticipated at the MP A811.3 bridge site…



aquifer. The Floridan aquifer limestone is overlain by a silty or clayey sand, clay, phosphate and limestone aquitard (or flow-retarding layer) ranging in thickness from nearly absent to greater than 100 feet and locally referred to as the Hawthorn formation. The Hawthorn formation is in turn overlain by a surficial layer of sand, on the order of 40 to 70 feet in thickness, bearing the water table aquifer. The likelihood of sinkhole occurrence at a given site within the region is determined by the relationship among these three layers, specifically by the water (and soil)-transmitting capacity of the Hawthorn formation at that location.

The water table aquifer is comprised of Recent and Pleistocene sands and is separated from the Eocene limestone of the Floridan aquifer by the Miocene sands, clays and limestone of the Hawthorn formation. Since the thickness and consistency of the Hawthorn layer is variable across Central Florida, the likelihood of groundwater flow from the upper to the lower aquifer (known as aquifer recharge) will also vary by geographical location. In areas

where the Hawthorn formation is absent, water table groundwater (and associated sands) can flow downward to cavities within the limestone aquifer, like sand through an hourglass, recharging the Floridan aquifer, and sometimes causing the formation of surface sinkholes. This process of subsurface erosion associated with recharging the Floridan aquifer is known as raveling. Thus, in Central Florida, areas of effective groundwater recharge to the Floridan aquifer have a higher potential for the formation of surface sinkholes.

No method of geological, geotechnical, or geophysical exploration is known that can accurately predict the occurrence of sinkholes. It is common geotechnical practice in Central Florida to make a qualitative prediction of sinkhole risk on the basis of local geological conditions in the vicinity of a particular site. Based on our review of the U.S. Geological Survey Map entitled “Recharge and Discharge Areas of the Floridan Aquifer in the St. Johns River Water Management District and vicinity, Florida,” 1984, the project is in an area of generally no recharge and, therefore, we can conclude it is in an area where the risk of sinkhole formation is low compared to the overall risk across Central Florida.

…the project is in… an area where the risk of sinkhole formation is low compared to the overall risk across Central Florida.



3.0 SUBSURFACE EXPLORATION GEC evaluated subsurface conditions at the MP A811.3 bridge replacement site by performing Standard Penetration Test (SPT) borings to depths ranging from 105.5 to 190.5 feet below existing ground surface. The locations and depths of our borings are summarized in the following table:

Table 3 Boring Locations and Depths

Bridge MP No.

Boring No. Station

Offset (ft)

Boring Depth (ft)

A811.3

B6-1 B6-2 B6-3 B6-4 B6-5 B6-6

42822+03 42823+06 42824+11 42825+63 42823+26 42825+04

32 LT 30 LT 30 LT 30 LT 24 RT 24 RT

158.0 190.5 126.5 115.0 163.0 105.5

GEC established the majority of the boring locations such that working limits, per the CSX Operating rules, were not required to be established. In compliance with Central Florida Rail Commission (CFRC) safety restrictions, SPT borings performed with a drill rig were required to be a minimum of 25 feet from the existing track. However, working limits were established for bridge borings B6-5 and B6-6 in order to evaluate subsurface conditions closer to the existing track alignment. Boring locations were not established by survey, but rather by using project plans and a handheld, sub-meter accuracy, Global Positioning Satellite (GPS) unit (Trimble GeoXT 500 Series). Although the boring and probe locations are, therefore, given only approximately, the methods used to locate them are, in GEC’s opinion, sufficient to meet the intent of this study. Ground surface elevations at the bridge boring locations were estimated by AECOM from project DTM survey data. The boring locations are referenced from the CFRC Centerline of Construction shown on project plans provided by AECOM.



3.1 SPT Borings SPT borings were drilled in general accordance with ASTM Procedure D-1586. The boreholes were advanced by the rotary wash method with bentonite-based mud used as the circulating fluid to stabilize the borehole. GEC’s field crew obtained SPT samples continuously in the borings to a depth of 10 feet and at 2.5-foot depth intervals thereafter. However, most boring locations were augered by hand the first four to six feet to avoid damage to underground, unmarked utilities. A GEC engineering technician monitored the drilling operation, and collected, examined and visually classified each sample. He then packaged representative portions of each sample for transport to our laboratory for further examination and laboratory testing. 3.2 Machine Auger Borings Machine auger borings were performed in general accordance with ASTM Procedure D-4700. Machine auger borings were performed by hydraulically turning a 4-inch wide continuous flight, solid-stem, auger into the ground in 5-foot increments until the desired boring termination depth was achieved. The auger flights were retrieved in 5-foot increments without further rotation and the soils retained on the auger were examined by our technician prior to collection of representative soil samples. The samples were placed in sealed jars and transported to GEC’s laboratory for further examination and limited laboratory testing. 3.3 Groundwater Measurement A GEC engineering technician measured the depth to the groundwater in the boreholes at the time of drilling and again after approximately 24 hours. Once the groundwater measurements were recorded, the boreholes were backfilled with soil cuttings to prevailing ground surface. At SPT borehole locations a hand auger boring was performed adjacent to each of the SPT boreholes to record the groundwater depth, since the SPT borings were grout-sealed immediately upon completion. 4.0 LABORATORY TESTING Selected soil samples obtained from the borings were tested in accordance with Florida Standard Testing Methods (FM). Florida Standard Testing Methods are adaptations of



recognized standard methods, e.g., ASTM and AASHTO, which have been modified to accommodate Florida’s geological conditions. The GEC laboratory is reviewed annually by the Construction Materials Engineering Council, Inc. (CMEC) to verify compliance with FM. Our laboratory testing program is summarized in the following Table:

Table 4 Summary of Laboratory Testing Program

Test Description No. of Tests

Percent Fines (FM 1-T88) 44 Grain Size Analysis (FM 1-T88) 5 Atterberg Limits (FM 1-T89/90) 16 Natural Moisture Content (FM 1-T265) 17 Organic Content (FM 1-T267) 1 Hydrometer Analysis (ASTM D-422) 1 Corrosion Series (FM 5-550/551/552/553) 3

Laboratory test results are presented adjacent to the soil boring profiles on the Report of SPT Borings sheets in the Appendix. Corrosion series tests were performed on representative soil and water samples obtained at the bridge location to evaluate the substructure environmental classification. In accordance with the FDOT Structure Design Guidelines and the results of our corrosion series test results, which are included in Table 6 in the Appendix, the substructure environmental classification for the MP A811.3 bridge site is summarized in the following table. The superstructure environmental classification is estimated to be slightly aggressive for concrete and steel bridge components.

Table 5 Bridge Substructure Environmental Classification Summary

Bridge/Culvert MP No.

Substructure Environmental Classification

Concrete Steel

A811.3 Moderately Aggressive Moderately Aggressive



Five grain size analyses and one hydrometer analysis were performed on representative samples of the surficial soils encountered in our bridge borings to determine laboratory D50 values for bridge hydraulic evaluation. The particle size distribution reports and a Summary of D50 Test Results table (Table 7) are included in the Appendix. 5.0 SUBSURFACE CONDITIONS The results of our borings are presented on the Report of SPT Boring sheets in the Appendix. The soils encountered in the SPT boring were classified in accordance with the Unified Soil Classification System (USCS) (SP-SM, SM, etc.). Soils were described using the ASTM soil descriptions (e.g., sand with silt). We based our classifications on visual examination and the limited laboratory testing performed. The boring logs and related information included in this report are indicators of subsurface conditions only at the specific boring location at the time of our field exploration. Subsurface conditions, including groundwater levels, at other locations of the subject site may differ from conditions we encountered at the boring locations. Moreover, conditions at the boring locations can change over time. Groundwater levels fluctuate seasonally, and soil conditions can be altered by earthmoving operations. The depths and thicknesses of the subsurface strata indicated on the boring logs were interpolated between samples obtained at different depths in the borings. The actual transition between soil layers may be different than indicated. 5.1 Bridge Boring Results In general, the bridge SPT borings performed for the MP A811.3 bridge encountered primarily loose to medium dense fine sand with varying silt and clay content to typical depths of 70 to 80 feet. Intermittent layers of clay and silt (CH, CL, ML) were encountered within this surficial sand layer. Below this surficial layer, the borings typically encountered medium dense to very dense fine sand with varying shell content to depths of 70 to 115 feet. This layer was underlain by loose to very dense weathered limestone, which extended to the boring termination depths of 115 to 190.5 feet. Notable exceptions to this general profile are given as follows:

Boring B6-5 encountered a potential void between approximate elevations -72 and -80.5 feet NAVD.



Boring B6-2 did not encounter the medium dense to very dense fine sand with varying shell content layer. Drilling fluid circulation loss occurred during drilling operations at boring locations B6-1, B6-2, B6-3 and B6-5 as indicated on the Boring Results sheets.

For specific subsurface conditions encountered at each boring location, please refer to the Report of SPT Borings for Structures sheets in the Appendix. 5.2 Groundwater Levels Groundwater levels were measured at least 24 hours after completion of the borings. Groundwater levels were generally encountered at elevations ranging from +52.5 to +60.4 feet NAVD88 at the boring locations. Groundwater levels can vary seasonally and with changes in subsurface conditions between boring locations. Alterations in surface and/or subsurface drainage brought about by site development can also affect groundwater levels. Therefore, groundwater depths measured at different times or at different locations on the site can be expected to vary from those measured by GEC during this investigation. For the purposes of this report, estimated seasonal high groundwater levels are defined as groundwater levels that are anticipated at the end of the wet season of a “normal rainfall” year under current site conditions. We define a “normal rainfall” year as a year in which rainfall quantity and distribution were at or near historical rainfall averages. GEC estimated seasonal high groundwater levels each boring location. Estimated seasonal high groundwater levels are anticipated to range from elevation +56.2 to +62.4 feet NAVD88 at the boring locations. However, at boring locations B6-3 and B6-6, the estimated seasonal high groundwater level is estimated to be above ground surface; indicated by “AGS” on the boring logs. Encountered and estimated seasonal high groundwater levels are shown adjacent to each boring profile on the Report of SPT Boring sheets in the Appendix.



6.0 ANALYSES AND RECOMMENDATIONS

The following recommendations are based on the structure design elements previously described and the subsurface conditions encountered in our borings. If the project design requirements change or if subsurface conditions are different from those described in this report, GEC should be retained to review and modify, if necessary, the following recommendations in light of such changes. 6.1 Foundation Design Alternatives GEC performed an evaluation of foundation alternatives that included shallow spread footings, drilled shafts, steel pipe piles, steel “H” piles and driven precast prestressed concrete (PPC) piles. The results of these foundation analyses are included in our Preliminary Report of Geotechnical Investigation, dated December 7, 2012. We understand that 18-inch Precast Prestressed Concrete (PPC) piles have been selected as the preferred foundation system for the proposed MP A811.3 bridge replacement at Shingle Creek. The following report sections provide analysis and recommendations for the selected foundation systems. 6.2 Axial Load Analysis GEC analyzed axial capacity for 18-inch concrete piles using the FDOT computer program FB-Deep Version 2.04, which is based on FDOT Research Bulletin RB-121. A Graph of Davisson Pile Capacity vs. Pile Tip Elevation and samples of the FB-Deep analyses are included in the Appendix.

Project plans provided by AECOM indicate that the existing 14-inch, timber piles at the MP A811.3 bridge site are to be cut at the existing ground surface and abandoned in place. Based on our review of the existing bridge bent configurations, each bent consists of 6 timber piles. From the existing bent centerline, the inner 2 piles are plumb with the following 2

piles installed at a 1:12 batter and the outer piles installed at a 2:12 batter. Based on our review of the proposed new, 18-inch PPC pile locations and the existing pile locations, the proposed piles do not appear to be in conflict with the existing pile locations.

Project plans… indicate that the existing 14-inch, timber piles… are to be cut at the existing ground surface and abandoned in place.



GEC was provided with Service Loads and scour elevations for each bridge bent. We used this information and a factor of safety of 2.5 to calculate the Nominal Bearing Resistances for each bent. Based upon this provided information, our Davisson Pile Capacity vs. Pile Tip Elevation curves and the calculated Nominal Bearing Resistances, pile design parameters for 18-inch PPC piles the proposed bridge are summarized in the Pile Data Table in the Appendix. FB-Deep results predict the long-term axial capacity after soil pore water pressures have had time to dissipate and skin friction capacity is fully regained. It may take several days after end-

of-drive to regain significant skin friction capacity. Because a consistent bearing stratum was not encountered, end bearing capacity is not expected to be a large component of total axial capacity. Therefore, set-checks and/or re-drives should be anticipated during both the test pile program and production pile installation to assess skin friction capacity gain at this site.

Elevations and capacities recommended in this report are for individual piles. The analyses and recommendations apply for piles spaced at minimum distances of three pile widths as measured from center to center. Group reductions would be required for more closely spaced piles. Because existing ground surface elevations are below the potential artesian head elevation of +58 feet NAVD as detailed in Section 2.3 of this Report, GEC recommends the following note be added to all Pile Data Table sheets in the project plan set:

Artesian conditions were not noted by the driller during drilling. However, based on review of the St. Johns River Water Management District potentiometric map of the upper Floridan Aquifer for the project area, the potential artesian head elevation is estimated to be +58 feet NAVD88. The Contractor shall be prepared to control artesian flow up to a head elevation of +58 feet NAVD88.

We recommend a test pile program be established for the proposed structure. The test piles should be instrumented with the Pile Driving Analyzer (PDA) in accordance with FDOT Specification 455. The substructure environmental classification for concrete substructure is moderately aggressive at the MP A811.3 bridge site. If concrete piles are selected, minimum concrete

...set-checks and/or re-drives should be anticipated during both the test pile program and production pile installation.



cover requirements should be accounted for in accordance with the FDOT Structures Design Guidelines. 6.3 Downdrag Settlement Considerations Based on project plans, embankment fill will be placed at the MP A811.3 bridge abutments. This fill will need to be placed after the abutment piles are driven. Therefore, soil settlement caused by fill loads at the end bent pile locations could generate downdrag loads on the piles. As previously described, the soil profile encountered in the borings is composed primarily of loose to very dense fine sands. Due to the cohesionless, granular nature of the majority of the subsurface profile, settlement of the sand profile caused by placement of the new embankment fill will occur concurrently during embankment construction. Once the embankment fill is complete, subsoil settlement will essentially cease and the superstructure can be constructed with negligible post-construction abutment fill settlement. Therefore, we do not anticipate that downdrag will be a significant factor in pile performance at this site. 6.4 Scour Resistance A total of 5 full grain size analyses and 1 hydrometer analysis were performed for the MP A811.3 bridge site. The D50 grain sizes were determined for use by the Drainage Engineer to calculate the 100 year scour elevations. GEC then performed scour resistance calculations for the proposed bridge based on the 100 year scour elevations, soil type and average SPT resistance values. Based on our review of the project plans, a riprap rubble scour protection is proposed for all bridge bents excluding bents 7N, 7S, 8N and 8S. Scour resistance was only calculated for those bent locations without scour protection. The grain size curves and scour resistance calculations are included in the Appendix. 7.0 SINKHOLE RISK As discussed in Section 2.4, the geology of some regions within Central Florida is conducive to the formation of sinkholes. Areas of “high recharge” from the water table aquifer to the underlying limestone aquifer are generally considered to exhibit a “high risk” of sinkhole activity compared to the background risk in Central Florida. The SunRail Phase 1 alignment, from the Debary Station to the Sand Lake Road Station, crosses several high recharge areas that have an elevated risk of sinkhole formation. These high risk areas have historically been developed with roadways and buildings, as well as rail. Sinkholes have occurred in these areas



in recent years, some requiring remedial measures due to their proximity to roadways and/or structures. Sinkhole risk for the CFRC Phase 1 alignment was discussed in the EarthTech (AECOM) memorandum dated February 26, 2008. However, the geology of the CRFC Phase 2 South alignment is significantly different than the geology of the Phase I alignment. The rail alignment from the Sand Lake Road Station to the Kissimmee Station is characterized as “low to moderate” recharge, and the rail alignment from the Kissimmee Station to the Poinciana Station is within a zone of “no recharge.” Therefore, the risk of sinkhole activity along the Phase II alignment is relatively low compared to the background risk in Central Florida. Further, deep Standard Penetration Test (SPT) borings performed for rail bridge replacements along the CFRC Phase 2 South alignment did not encounter strong indicators of ongoing sinkhole activity including soil voids, extensive zones of very loose soil or drilling fluid losses in the soils above the limestone formation. There is currently no methodology that can accurately predict the occurrence of sinkholes. Geophysical methods, such as Ground Penetrating Radar, and deep soil borings can only provide subsurface information that is useful in evaluating relative sinkhole risk. These methods are often used on proposed major structure sites in high risk sinkhole locations to evaluate relative risk, but they are far from definitive in predicting the occurrence of sinkholes. Sinkhole risk evaluations, including deep soil borings, are not typically performed for horizontal facilities such as roadways (or rail lines) since the cost of performing such an evaluation could not be justified based on the benefit derived.

The potential for a sinkhole to occur during the design or construction of SunRail Phase 1 or Phase 2 South project is relatively low. As discussed in the previous memorandum several sinkholes did occur during the most recent widenings of Interstate 4 in Orange and Seminole Counties, and GEC was involved in the remediation of several of

these subsidences. These events impacted traffic and required remediation that caused additional project costs and delays. However, it is highly unlikely that even the most detailed and costly sinkhole investigation techniques available would have predicted those occurrences.

The potential for a sinkhole to occur during the design or construction of SunRail Phase 1 or Phase 2 South project is relatively low.



8.0 USE OF THIS REPORT

GEC has prepared this report for the exclusive use of our client, AECOM and the Florida Department of Transportation District 5, and for specific application to this project. GEC will not be held responsible for any other party’s interpretation or use of this report’s subsurface data or engineering analysis without our written authorization. The sole purpose of the borings performed by GEC at this site was to obtain indications of subsurface conditions as part of a geotechnical exploration program. GEC has not evaluated the soil from the borings for the potential presence of contaminated soil or groundwater, nor have we subjected any soil samples to analysis for contaminants. GEC has strived to provide the services described in this report in a manner consistent with that level of care and skill ordinarily exercised by members of our profession currently practicing in Central Florida. No other representation is made or implied in this document.

APPENDIX

PILE DATA TABLE

Pile Data TableSunrail Phase 2 South

MP A811.3 Shingle Creek BridgeFPID No. 423446 9 52 01GEC Project No. 2135G6

Page 1 of 1

PPCPileSize(in)

1NominalBearing

Resistance(tons)

TensionResistance(tons)

MinimumPile TipElevation(ft NAVD)

Test PileLength(ft)

RequiredPreformElevation(ft NAVD)

2FactoredDesignLoad(tons)

3ServiceLoad(tons)

Downdrag(tons)

Total ScourResistance(tons)

Net ScourResistance(tons)

100 YearScour

Elevation(ft NAVD)

Long TermScour

Elevation(ft NAVD)

ResistanceFactor

Compression

ResistanceFactorTension

1 B6 1 +60 15.0 18 193 N/A +0.0 90 N/A 125 77 N/A N/A N/A N/A N/A 0.65 N/A2 B6 1 +60 15.0 18 175 N/A +0.0 90 N/A 113 70 N/A N/A N/A N/A N/A 0.65 N/A3 B6 1 +60 15.0 18 178 N/A +0.0 90 N/A 115 71 N/A N/A N/A N/A N/A 0.65 N/A4 B6 5 +60 25.0 18 178 N/A +0.0 100 N/A 115 71 N/A N/A N/A N/A N/A 0.65 N/A5 B6 5 +60 25.0 18 178 N/A +0.0 100 N/A 115 71 N/A N/A N/A N/A N/A 0.65 N/A6 B6 5 +60 25.0 18 178 N/A +0.0 100 N/A 115 71 N/A N/A N/A N/A N/A 0.65 N/A7 B6 3 +60 35.0 18 285 N/A 15.0 110 N/A 159 88 N/A 26 26 +31.7 N/A 0.65 N/A8 B6 3 +60 35.0 18 285 N/A 15.0 110 N/A 159 88 N/A 26 26 +31.7 N/A 0.65 N/A9 B6 6 +60 25.0 18 183 N/A 20.0 100 N/A 118 73 N/A N/A N/A N/A N/A 0.65 N/A10 B6 6 +60 25.0 18 183 N/A 20.0 100 N/A 118 73 N/A N/A N/A N/A N/A 0.65 N/A11 B6 6 +60 25.0 18 183 N/A 20.0 100 N/A 118 73 N/A N/A N/A N/A N/A 0.65 N/A12 B6 4 +60 30.0 18 193 N/A 5.0 105 N/A 125 77 N/A N/A N/A N/A N/A 0.65 N/A

Notes

1. Recommended Nominal Bearing Resistance:

2. Based on a soil resistance factor of 0.65.

3. Based on an approximate overall factor of safety of 2.5.

MPA811.3

BoringNo.Bridge

BentNo.

ApproximatePile Cut OffElevation(ft NAVD)

Pile Recommendations

AnticipatedPile TipElevation(ft NAVD)

DAVISSON PILE CAPACITY VS. PILE TIP ELEVATION GRAPH

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

+0

+10

+20

+30

+40

+50

+60

+70

0 50 100 150 200 250 300

PILE

TIP

ELE

VATI

ON

(FT

NAV

D)

DAVISSON PILE CAPACITY (TONS)

18-IN SQUARE PPC PILESSunrail Phase 2 South

Bridge MP A811.3 (Shingle Creek)Financial Project No. 412994-2-32-01


B6-1 B6-2 B6-3 B6-4 B6-5 B6-6

USGS QUADRANGLE AND NRCS SOIL SURVEY MAPS

BORING LOCATION PLAN AND SPT BORING RESULTS

SUMMARY OF CORROSION SERIES TEST RESULTS

Table 6Summary of Corrosion Series Test Results

Sunrail Phase 2 SouthGEC Project No. 2135G6

Page 1 of 1

Concrete Steel

A811.3 B6-1 SC 2 - 6 7.2 3,700 105 30 Slightly Aggressive Moderately AggressiveA811.3 B6-3 Water --- 6.4 3,900 50 66 Slightly Aggressive Moderately AggressiveA811.3 B6-4 SC 2 - 8 6.8 2,000 90 15 Moderately Aggressive Moderately Aggressive

Bridge No.Chlorides

(ppm)Sulfates (ppm)

Substructural Environmental ClassificationBoringNo.

USCSSymbol

Sample Depth (feet)

pHMinimum Resistivity (ohm-cm)

SUMMARY OF D50 TEST RESULTS AND PARTICLE SIZE

DISTRIBUTION CURVES

Table 7Summary of D50 Test Results

Sunrail Phase 2 SouthGEC Project No. 2135G6

Page 1 of 1

A811.3 B6-1 42822+03 32 LT SC 2 - 6 63.5 - 59.5 0.097A811.3 B6-1 42822+03 32 LT SP 8 - 10 57.5 - 55.5 0.103A811.3 B6-2 42823+06 30 LT SP-SM 0 - 2 58.5 - 56.8 0.106A811.3 B6-2 42823+06 30 LT SM 8 - 10 50.5 - 48.5 0.098A811.3 B6-3 42824+11 30 LT SP 7 - 9 46.2 - 44.2 0.223A811.3 B6-3 42824+11 30 LT SM 13 - 15 40.2 - 38.2 0.099

D50

(mm)StationOffset(feet)

Bridge/CulvertNo.

BoringNo.

USCSSymbol

Sample Depth (feet)

Sample Elevation

(feet NAVD88)

SCOUR RESISTANCE CALCULATIONS

Scour Resistance CalculationsSunrail Phase 2 South

Bridge MP A811.3 (Shingle Creek): Bents 7 & 8Financial Project No. 423446-9-52-01


Layer Soil Average Ultimate Side Layer Pile Surface Scour ResistanceNumber Type N Friction Thickness Area from

(tsf) (ft) (sf/ft) Design Chart(tons)

1 3 7 0.139 14.5 6.0 12.121 3 17 0.323 7.0 6.0 13.57

Total Scour Resistance 26

BORING B6-3 (ELEVATION +53.2 TO +31.7 FT NAVD)18" Square Prestressed Concrete Pile

SAMPLE FB DEEP ANALYSES

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