REPORT OF GEOTECHNICAL EXPLORATION AND ENGINEERING ANALYSIS

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1 FIGURE 3 Geotechnical Report (2) REPORT OF GEOTECHNICAL EXPLORATION AND ENGINEERING ANALYSIS RIVER TOWER RESTORATION RIVER TOWER PARK TAMPA, FLORIDA AREHNA PROJECT NO. B February 22, 2013 Prepared For: Southwest Florida Water Management District 7601 US Highway 301 North Mail Code: TPA-2-NSR Tampa, Florida Prepared By: AREHNA Engineering, Inc West Lemon Street Tampa, Florida 33609

2 5012 W. Lemon Street, Tampa, Florida Ph Fax February 22, 2013 Ms. Stephanie T. Powers Southwest Florida Water Management District 7601 US Highway 301 North Mail Code: TPA-2-NSR Tampa, Florida (813) Ext (813) Fax Subject: Report of Geotechnical Exploration and Engineering Analysis River Tower Restoration (River Tower Park) Tampa, Florida AREHNA Project B Dear Ms. Powers: AREHNA Engineering, Inc. (AREHNA) is pleased to submit this report of our geotechnical exploration and engineering analysis for the proposed project. Services were conducted in general accordance with AREHNA Proposal Prop dated December 18, The purpose of our geotechnical study was to obtain information on the general subsurface conditions for the proposed drainage improvements. This report presents our understanding of the project, outlines our exploratory procedures, documents the field test data obtained and includes our recommendations for on-site soil suitability. AREHNA appreciates the opportunity to have assisted the Southwest Florida Water Management District on this project. Should you have any questions with regards to this report, or if we can be of any further assistance, please contact this office. Best Regards, AREHNA ENGINEERING, INC. FLORIDA BOARD OF PROFESSIONAL ENGINEERS CERTIFICATE OF AUTHORIZATION NO Alex Rodriguez, E.I. Geotechnical Engineer Amanda S. Pereira, P.E. Senior Geotechnical Engineer Florida Registration Distribution: 3 Addressee 1 File

3 TABLE OF CONTENTS Page 1.0 EXECUTIVE SUMMARY PROJECT INFORMATION AND SCOPE OF WORK Site Description and Project Characteristics Scope of Work FIELD EXPLORATION AND LABORATORY TESTING Field Exploration Laboratory Testing LABORATORY TESTING SUBSURFACE CONDITIONS USDA Natural Resources Conservation Service Data USGS Topographic Data Subsurface Conditions Ground Water Conditions Estimated Seasonal High Ground Water Level On-Site Soil Suitability LIMITATIONS... 8 APPENDIX A Project Site Location Map Figure 1 Field Exploration Plan - Figure 2 USGS Topographic Survey Figure 3 USDA Soil Survey Map - Figure 4 APPENDIX B Table 1 - Summary of GPS Coordinates Generalized Subsurface Profile Figure 5 Soil Boring Records Key to Soil Classifications Symbols APPENDIX C Field Procedures Laboratory Procedures Table 2 Laboratory Results LIST OF APPENDICES

4 1.0 EXECUTIVE SUMMARY The purpose of this geotechnical exploration was to obtain information regarding the general subsurface conditions at the site. The planned drainage improvements include the addition of a stormwater retention area located near the eastern portion of the site. The project site is located at the southeast quadrant of the intersection of East Bird Street and North Florida Avenue in Tampa, Florida. The borings performed at the site encountered sands generally increasing in fines content with depth (SP, SP- SC and SC) to the respective termination depths. Within the proposed pond area, borings B-02 and B-03 encountered clayey soils (SC and CH) at a depth of 4 feet. The ground water level was not discernible within the upper 6 to 8 feet of the sandy soils encountered within borings B-01 and B-04. The ground water level was also not noted within sandy soils in the upper 4 feet of borings B-02 and B-03, where clayey soils were encountered thereafter.

5 2.0 PROJECT INFORMATION AND SCOPE OF WORK 2.1 Site Description and Project Characteristics The project site is currently under consideration for the placement of a stormwater retention area near the southeast portion of the park. The site currently consists of an open grassy field with a few large trees scattered throughout. Several large trees and some shrubbery line the east and south sides of the project area. The south side of the project area is also bordered by the Hillsborough River. The site appears to drain from north to south, towards the river. 2.2 Scope of Work The purpose of our geotechnical study was to obtain information on the general subsurface conditions of the soils surrounding and underlying the proposed stormwater retention area. The subsurface materials encountered were then evaluated with respect to the available project characteristics. The following services were performed to achieve the above-outlined objectives: Requested utility location services from Sunshine State One-Call. Coordinated site access and marked boring locations as approved by Ms. Stephanie Powers (SWFWMD) and Mr. Tom Reis (Scheda) during an on-site meeting. Performed four Standard Penetration Test () borings utilizing a track-mounted rig in the area of the proposed pond and near structure S-3A. Samples were collected and Standard Penetration Test resistances were recorded at approximate intervals of two feet for the top ten feet and at approximate intervals of five feet thereafter. Visually classified and stratified soil samples in the laboratory using the Unified Soil Classification System and conducted a laboratory testing program consisting of natural moisture content, Atterberg limits and grain size analysis on representative samples, as deemed necessary. Reported the results of the field exploration, lab testing, and engineering analysis. The results of the subsurface exploration are presented in this written report, signed and sealed by a professional engineer specializing in geotechnical engineering.

6 3.0 FIELD EXPLORATION AND LABORATORY TESTING 3.1 Field Exploration The borings were performed with the use of a Power Drill Rig using Bentonite Mud drilling procedures. Samples were collected and Standard Penetration Test resistances were measured at approximate intervals of two feet for the top ten feet and at approximate intervals of five feet thereafter. The soil sampling was performed in general accordance with ASTM Test Designation D-1586, entitled Penetration Test and Split-Barrel Sampling of Soils. Representative portions of these soil samples were sealed in glass jars, labeled and transferred for appropriate testing and classification. The soil boring records and key to classification are attached in Appendix B of this report. The locations of the borings were confirmed by SWFWMD. 3.2 Laboratory Testing The soil samples were transported to AREHNA s soil laboratory and were classified by the Geotechnical Engineer using the USCS in general accordance with the ASTM Test Designation D Laboratory tests included grain size analysis, natural moisture content, and Atterberg limits. The test results are presented in Table 2, Appendix C.

7 4.0 LABORATORY TESTING Laboratory tests were performed on representative soil samples in order to classify the soil and to evaluate its engineering properties. Laboratory testing, performed in general accordance with ASTM Standards, included Atterberg limits, moisture content and single sieve (#200) grain size. Laboratory test results are presented below, and hare also included as Table 2 in Appendix C. Boring No. Sample Depth (feet) Percent Moisture Content Percent Finer (-200 sieve) Liquid Limit Plasticity Index B B B B B B B Our Laboratory Procedures are presented in Appendix C.

8 5.0 SUBSURFACE CONDITIONS 5.1 USDA Natural Resources Conservation Service Data A review of the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) survey for Hillsborough County, attached as Figure 4 in Appendix A, indicates that the soils in the vicinity of the project site consists of Urban land (mapping unit 56). The NRCS published profiles typically reports soils extending to 80 inches below the ground surface. Excerpts from the published Soil Survey are provided below for reference. Characteristics of Urban land [56]: This map unit consists of miscellaneous areas that are covered by concrete, asphalt, buildings, or other impervious surfaces that obscure or alter the soils so that identification is not feasible. The slope is predominantly less that 2 percent, but it ranges from less that 2 percent to 5 percent. In areas mapped as Urban land, 85 percent or more of the surface is covered by streets, parking lots, buildings and other structures. In moderately built-up areas, these structures cover 50 to 85 percent of the surface. Present land use precludes the use of this miscellaneous area for cultivated crops, pasture, or commercial trees. Open areas generally are used for lawns, parks, playgrounds, cemeteries, or open spaces. Based on the borings performed, the shallow soils below grade generally consist of sandy soils (SP, SP- SC). 5.2 USGS Topographic Data The topographic survey map published by the United States Geological Survey was reviewed for ground surface features at the proposed project locations (Figure 3, Appendix A). Based on this review, the natural ground surface elevations at the project site slope downward to the south from approximately +20 to less than +10 feet National Geodetic Vertical Datum of 1929 (NGVD). 5.3 Subsurface Conditions The following soil conditions highlight the general subsurface stratification. The Soil Test Boring Records in Appendix B should be consulted for a detailed description of the subsurface conditions encountered at the boring location. When reviewing the boring record, it should be understood that soil conditions may vary between and away from the boring locations. Borings B-01, B-02 and B-03 were positioned within the area of the proposed stormwater retention area, located near the southeast corner of the park. Boring B-04 was placed adjacent to structure S-3A, located near the northeast corner of the project site. The coordinates for each boring are included as Table 1 in Appendix B.

9 Boring B-01 encountered sands generally increasing in fines content with depth (SP, SP-SC and SC) to the termination depth of 8.5 feet, where the boring encountered a drill bit refusal on rock. Boring B-02 encountered slightly clayey fine sand (SP-SC) and clayey fine sand (SC), underlain by a layer of very soft limestone (WLS) between approximately 8 and 13 feet. Clayey soils (CL-ML and CH) were then penetrated, with limestone (LS) encountered between 23 feet and the termination depth of 25 feet. Boring B-03 encountered 4 feet of fine sand (SP) underlain by high plasticity clay (CH) to a depth of 8 feet. Clayey fine sand (SC) was then penetrated, followed by the limestone (LS) formation between approximately 13 feet and the termination depth of 14 feet. Boring B-04 encountered 6 feet of fine sand (SP), followed by clayey fine sand (SC). Between approximately 18 feet and the termination depth of 19 feet, a no-recovery zone along with a drill bit refusal, likely on limestone, was encountered. A page defining the terms and classification symbols used in the boring profiles is included in Appendix B of this report. 5.4 Ground Water Conditions The ground water level was not encountered within the upper sandy soil stratums of the borings performed. The sandy soils extended to an approximate depth of 4 to 8 feet, where soil strata containing an increased percent fines content (SC and CH) were encountered. Where the more cohesive soils were encountered, the borings were advanced using mud-rotary methods, which precludes the determination of the depth of the water level once mud is introduced in the borehole. It should be noted that the borings were completed in February, which historically follows a dry period where lower ground water levels are normally recorded. Due to the presence of the clayey soils, the groundwater level may be a temporary perched condition in some areas, during the wetter times to the year. Fluctuation in ground water levels should also be expected due to seasonal climatic changes, construction activity, rainfall variations, surface water runoff, tidal fluctuations and other site-specific factors. Since ground water level variations are anticipated, design drawings and specifications should accommodate such possibilities and construction planning should be based on the assumption that variations will occur. 5.5 Estimated Seasonal High Ground Water Level Based on the mapping performed by the USDA, soils information obtained from the site and our experience in the area, we estimate that the seasonal high ground water level is approximately 2 to 3 feet below grade, with higher levels after severe storm events.

10 5.6 On-Site Soil Suitability The borings indicate that the majority of the soils encountered in the upper 4 to 6 feet should be generally suitable for fill. Classification indicates the majority of the upper 4 to 6 feet of the soils at this site consist of coarse grained material classified as SP and SP-SC, based on the Unified Soil Classification System (USCS). Materials excavated from the pond area below a depth of 4 feet may not be favorable for use as structural fill in the vicinity of borings B-02 and B-03. Suitable structural fill materials should consist of fine to medium sand with less than 12 percent passing the No. 200 sieve, and be free of rubble, organics, clay, debris and other unsuitable material.

11 6.0 LIMITATIONS The analysis and recommendations submitted in this report are based upon the data obtained from the soil borings performed at the locations indicated. Regardless of the thoroughness of a geotechnical exploration, there is always a possibility that conditions may be different from those at specific boring locations and that conditions will not be as anticipated by the designers or contractors. In addition, the construction process itself may alter soil conditions. AREHNA is not responsible for the conclusions, opinions or recommendations made by others based on the data presented in this report.

12 APPENDIX A Project Site Location Map Figure 1 Field Exploration Plan - Figure 2 USGS Topographic Survey Figure 3 USDA Soil Survey - Figure 4

: B-13-002 Date: February 19, 2013 5012 West Lemon Street, Tampa,

13 Project Site Location River Tower Restoration Tampa, Florida PROJECT SITE LOCATION MAP Client: SWFWMD Project No.: B Date: February 19, West Lemon Street, Tampa, FL Phone Fax Checked By: Drawn By: ASP DAR FIGURE 1

East Bird Street B-04 B-03 River Tower Restoration Parcel B-02 B-01 LEGEND B-# Standard Penetration Test Boring River Tower Restoration Tampa, Florida FIELD EXPLORATION LOCATION

14 East Bird Street B-04 B-03 River Tower Restoration Parcel B-02 B-01 LEGEND B-# Standard Penetration Test Boring River Tower Restoration Tampa, Florida FIELD EXPLORATION LOCATION MAP Client: SWFWMD Project No.: B Date: February 19, West Lemon Street, Tampa, FL Phone Fax Checked By: Drawn By: ASP DAR FIGURE 2

: B-13-002 Date: February 19, 2013 5012 West Lemon Street, Tampa, FL 33609

15 Project Site Location Source: USGS Topographic Map, Tampa, FL River Tower Restoration Tampa, Florida USGS TOPOGRAPHIC MAP Client: SWFWMD Project No.: B Date: February 19, West Lemon Street, Tampa, FL Phone Fax Checked By: Drawn By: ASP DAR FIGURE 3

16 Project Site Location Soil Mapping Unit 56 Urban land Source: USDA NRCS Soil Survey, Hillsborough County, FL River Tower Restoration Tampa, Florida USDA SOIL SURVEY MAP Client: SWFWMD Project No.: B Date: February 19, West Lemon Street, Tampa, FL Phone Fax Checked By: Drawn By: ASP DAR FIGURE 4

17 APPENDIX B Table 1 Summary of GPS Coordinates Generalized Subsurface Profile Figure 5 Soil Boring Records Key to Soil Classifications Symbols

18 TABLE 1 SUMMARY OF GPS COORDINATES River Tower Restoration River Tower Park, Tampa, Florida AREHNA Project No. B Boring No. Latitude Longitude B B B B

19 5012 W. Lemon Street Tampa, FL Date: 2/20/2013 Drawn By: VAF Checked By: AR River Tower Rest. Tampa, FL Prepared for Southwest Florida Water Management District Project No.: B GENERALIZED SUBSURFACE PROFILE Figure 5 Poorly-graded Sand Poorly-graded Sand with Clay Clayey Sand Weathered Limestone Low Plasticity Silty Clay High Plasticity Clay Limestone Soil Classification Key 0 B-01 2/7/2013 B-02 2/7/2013 B-03 2/7/2013 B-04 2/7/ SP SP-SC SP 2 SP 4 N= 22 N= 9 N= 16 N= SP-SC N= 19 SC N= 8 CH N= 10 N= 38 6 SC 8 SC N= 100+ N= 2 N= 10 N= 8 8 Depth (ft) BORING TERMINATED 8.5 ft WLS SC N= 9 WLS N= 100+ SC N= CL-ML BORING TERMINATED 14 ft N= 100+ N= CH BORING TERMINATED 19 ft LS N= BORING TERMINATED 25 ft 26

20 DEPTH (ft) SOIL DESCRIPTION AND REMARKS WATER LEVEL GRAPHIC LOG SAMPLE TYPE BLOW COUNTS N-VALUE N VALUE PL MC LL FINES CONTENT (%) 0 Medium dense brown fine SAND (SP) AU AU Medium dense tan slightly clayey fine SAND (SP-SC) with some shell fragments Very dense gray and brown clayey fine SAND (SC) with rock fragments 50 blows for 8 feet Refusal on rock and chert fragments Bottom of borehole at 8.5 feet /4" >> Date Drilled: 2/7/13 Drilled By: AREHNA Method: ASTM D-1586, Standard Penetration Test Boring Ground Water Level: Groundwater not encountered in top 8 feet Remarks: RIVER TOWER REST. TAMPA, FL AREHNA Project No.: B Southwest Florida Water Management District Drawn By: VAF Checked By: AR Date: 2/20/2013 SOIL BORING LOG Boring B-01 PAGE 1 OF 1

21 DEPTH (ft) SOIL DESCRIPTION AND REMARKS WATER LEVEL GRAPHIC LOG SAMPLE TYPE BLOW COUNTS N-VALUE N VALUE PL MC LL FINES CONTENT (%) 0 Medium dense tan slightly clayey fine SAND (SP-SC) AU AU Loose gray clayey fine SAND (SC) Very soft weathered LIMESTONE (WLS) with clay WOH for 8 feet WOH-WOH Stiff gray silty CLAY (CL-ML) with some limestone Hard green and gray high plasticity CLAY (CH) with traces of chert and limestone 50 blows for 18.5 feet 50/4" 100+ >> Hard LIMESTONE (LS) 50 blows for 24.5 feet Bottom of borehole at 25.0 feet /4" 100+ >> Date Drilled: 2/7/13 Drilled By: AREHNA Method: ASTM D-1586, Standard Penetration Test Boring Ground Water Level: Groundwater not encountered in top 4 feet Remarks: RIVER TOWER REST. TAMPA, FL AREHNA Project No.: B Southwest Florida Water Management District Drawn By: VAF Checked By: AR Date: 2/20/2013 SOIL BORING LOG Boring B-02 PAGE 1 OF 1

22 DEPTH (ft) SOIL DESCRIPTION AND REMARKS WATER LEVEL GRAPHIC LOG SAMPLE TYPE BLOW COUNTS N-VALUE N VALUE PL MC LL FINES CONTENT (%) 0 Medium dense tan and brown fine SAND (SP) AU AU Stiff to very stiff tan and green sandy high plasticity CLAY (CH) Loose tan clayey fine SAND (SC) with weathered limestone fragments Very hard weathered LIMESTONE (WLS) with some clay 50 blows for 13.5 feet Bottom of borehole at 14.0 feet. 50/1" 100+ >> Date Drilled: 2/7/13 Drilled By: AREHNA Method: ASTM D-1586, Standard Penetration Test Boring Ground Water Level: Groundwater not encountered in top 4 feet Remarks: RIVER TOWER REST. TAMPA, FL AREHNA Project No.: B Southwest Florida Water Management District Drawn By: VAF Checked By: AR Date: 2/20/2013 SOIL BORING LOG Boring B-03 PAGE 1 OF 1

23 DEPTH (ft) SOIL DESCRIPTION AND REMARKS WATER LEVEL GRAPHIC LOG SAMPLE TYPE BLOW COUNTS N-VALUE N VALUE PL MC LL FINES CONTENT (%) 0 Loose to medium dense gray and brown fine SAND (SP) AU AU Dense tan and gray indurated clayey fine SAND (SC) Loose tan and gray clayey fine SAND (SC) No recovery 50 blows for 18.5 feet Bottom of borehole at 19.0 feet. 50/0" 100+ >> Date Drilled: 2/7/13 Drilled By: AREHNA Method: ASTM D-1586, Standard Penetration Test Boring Ground Water Level: Groundwater not encountered in top 6 feet Remarks: RIVER TOWER REST. TAMPA, FL AREHNA Project No.: B Southwest Florida Water Management District Drawn By: VAF Checked By: AR Date: 2/20/2013 SOIL BORING LOG Boring B-04 PAGE 1 OF 1

24 KEY TO SYMBOLS CLIENT Southwest Florida Water Management District PROJECT NUMBER B LITHOLOGIC SYMBOLS (Unified Soil Classification System) SP: Poorly-graded Sand SP-SC: Poorly-graded Sand with Clay PROJECT NAME PROJECT LOCATION River Tower Rest. Tampa, FL SAMPLER SYMBOLS Hand Auger Standard Penetration Test SC: Clayey Sand WLS: Weathered Limestone CL-ML: Low Plasticity Silty Clay CH: High Plasticity Clay LS: Limestone Standard Penetration Resistances SAND & GRAVEL SILT & CLAY No. of Blows Greater than 50 No. of Blows Greater than 30 Relative Density Very Loose Loose Medium Dense Dense Very Dense Consistencey Very Soft Soft Firm Stiff Very Stiff Hard LIMESTONE No. of Blows /3" Greater than 50/3" Consistencey Soft Medium Hard Very Hard WOR = Weight of Rod WOH = Weight of Hammer Ground Water Level Measurements Water Level at Time Drilling, or as Shown Water Level After 24 Hours, or as Shown LL PI W DD NP PP - ABBREVIATIONS LIQUID LIMIT (%) PLASTICITY INDEX (%) MOISTURE CONTENT (%) DRY DENSITY (PCF) NON PLASTIC PERCENT PASSING NO. 200 SIEVE POCKET PENETROMETER (TSF) FINE GRAINED SOILS SILT or CLAY # 200 Sieve SOIL BOUNDARY CLASSIFICATIONS SAND GRAVEL Fine Medium Coarse Fine Coarse #40 Sieve COARSE GRAINED SOILS #10 Sieve #4 Sieve 3/4-inch 3-inch Cobbles 12-inch Boulders

25 APPENDIX C Field Procedures Laboratory Procedures Table 2 - Laboratory Test Results

26 Standard Penetration Test () Borings FIELD PROCEDURES The borings are performed in general accordance with ASTM D-1586, "Penetration Test and Split-Barrel Sampling of Soils." A rotary drilling process is used and bentonite drilling fluid is circulated in the boreholes to stabilize the sides and flush the cuttings. At regular intervals, the drilling tools are removed and soil samples are obtained with a standard 2-feet long, 2-inch diameter split-tube sampler. The sampler is first seated 6 inches and then driven an additional foot with blows of a 140-pound automatically tripped hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot is designated the "Penetration Resistance." The penetration resistance, when properly interpreted, is an index to the soil strength and density.

LABORATORY PROCEDURES Water Content The water content is the ratio, expressed as a percentage, of the weight of water in a given mass of soil to the weight of the solid particles.

27 LABORATORY PROCEDURES Water Content The water content is the ratio, expressed as a percentage, of the weight of water in a given mass of soil to the weight of the solid particles. This test is conducted in general accordance with FM 1-T265. Atterberg Limits (Plasticity) A soil's Plasticity Index (PI) is the numerical difference between the Liquid Limit (LL) and the Plastic limit (PL). The LL is the moisture content at which the soil will flow as a heavy viscous fluid and is determined in general accordance with ASTM D The PL is the moisture content at which the soil begins to crumble when rolled into a small thread and is also determined in general accordance with FM 1-T 90. Fines Content In this test, the sample is dried and then washed over a No. 200 mesh sieve. The percentage of soil by weight passing the sieve is the percentage of fines or portion of the sample in the silt and clay size range. This test is conducted in general accordance with ASTM D-1140.

28 TABLE 2 SUMMARY OF LABORATORY TEST RESULTS River Tower Restoration River Tower Park, Tampa, Florida AREHNA Project No.: B Boring No. Sample Depth (feet) Percent Moisture Content Percent Finer (-200 sieve) Liquid Limit Plasticity Index B B B B B B B

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