Braun Property report -

W o r l d w i d e E n g i n e e r i n g , E n v i r o n m e n t a l , C o n s t r u c t i o n , a n d I T S e r v i c e s

Subsurface Exploration and Geotechnical Evaluation Services

Roadway & Pond Areas Braun Property

Hillsborough County, Florida

Taylor Morrison 551 North Cattleman Road, Suite 200

Sarasota, Florida 34232

MARCH 18, 2014 REF. NO. 095642 (01)

Prepared by: Conestoga‐Rovers & Associates 4019 East Fowler Avenue Tampa, Florida U.S.A. 33617

Office: (813) 971‐3882 Fax: (813) 971‐1862

web: http://www.CRAworld.com

4019 East Fowler Avenue, Tampa, Florida 33617 Telephone: (813) 971-3882 Fax: (813) 971-1862 www.CRAworld.com

Worldwide Engineering, Environmental, Construction, and IT Services

Equal Employment Opportunity Employer

March 18, 2014 Reference No. 095642 Mr. Alex Azan, P.E. TaylorMorrison Via Electronic and Regular Mail 551 North Cattlemen Road, Suite 200 Sarasota, Florida 34232 Dear Mr. Alex Azan: Re: Report of Subsurface Exploration and

Geotechnical Evaluation Services Roadway & Pond Areas Braun Property

Hillsborough County, Florida As authorized, Conestoga‐Rovers & Associates, Inc. (CRA) has completed the requested subsurface exploration and geotechnical engineering evaluation within the proposed stormwater collection pond areas and alone the roadway alignments at the Braun Property located in Hillsborough County, Florida. This report provides the results of the field and laboratory studies, and discusses general geotechnical considerations for the planned roadways and ponds within the proposed residential subdivision development. Based on our interpretation of the subsurface conditions from the borings and our understanding of the proposed pond and roadway construction, geotechnical engineering conclusions and recommendations addressing subsurface conditions, pavement design considerations and estimated normal wet season high groundwater levels are presented herein.

General Summary

Based on the shallow subsurface conditions encountered, the soils encountered within the vertical limits of the borings performed will adequately support the anticipated roadways. The roadway Structural Number of 2.44 proposed by Waldrop is greater than the minimum Structural Number of 2.3, as indicated in the Hillsborough County Transportation Technical Manual for Subdivisions and Site Development Projects, September 1, 2009. Based on the proposed roadway section thicknesses and associated structural coefficients, this pavement section is considered acceptable, assuming a minimum separation of 18 inches is maintained between the bottom of the pavement base and seasonal high groundwater levels. Based on subsurface conditions and estimated ground surface elevations, the depth to the estimated seasonal high groundwater within the borings performed will be between 0.5 feet and 1.0 feet. Estimated seasonal high groundwater elevations at each boring location are provided in the report. Additionally, the encountered sand deposits are also considered acceptable for structure and pavement fill.

March 18, 2014 Reference No. 095642

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Project Information

Site Location and Project Description

CRA, previously performed a site suitability study at the site consisting of ten Standard Penetration Test (SPT) borings spread across the “upland areas” of the property. As requested, addition soil borings were needed to identify subsurface conditions and estimate seasonal high groundwater levels along the proposed roadway alignments, as well as within the proposed stormwater collection ponds. The site will be developed with multi‐family buildings, associated roadways and stormwater collection areas. The subject property is located at the southeast corner of the Sheldon Road and Gonzalez Lake Drive intersection in Hillsborough County, Florida. The subject property is relatively square in shape and is covered with dense vegetation and some wetlands. Predominantly, residential and commercial properties surround the property. An aerial photograph of the site is presented as the base map in Figure 1. Relying on topographic information developed by the U.S. Geological Survey (USGS), the site varied in elevation from approximately El. 24 feet to approximately El. 29 feet, based on the National Geodetic Vertical Datum (NGVD) of 1929. A Conceptual Site Plan provided by Waldrop Engineering is overlaid onto the aerial photograph in Figure 1.

Purpose and Scope of Work

The general scope of work for the roadway and pond areas geotechnical services performed is outlined below:

Coordinated utility notification through Sunshine State One Call of Florida, Inc.;

Provided drill rig access through clearing;

Mobilized a drill rig to the project site;

Identified the boring locations proposed by Waldrop Engineering within the proposed roadway alignments as well as within the stormwater collection areas using aerial photography and a Global Positioning System (GPS) unit;

Performed a total of eleven power auger borings along the proposed roadway alignments to a nominal depth of 8 feet. The power auger borings were performed with machine advanced flight augers;


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Performed a total of four Standard Penetration Test (SPT) borings to a nominal depth of 20 feet within the proposed stormwater collection ponds areas in general accordance with ASTM D‐1586 (Standard Test Method for Penetration Test and Split Barrel Sampling of Soils);

Documented soil and groundwater conditions encountered in the borings and collected soil samples for laboratory review;

Reviewed the Hillsborough County Soil Survey (SCS) pertaining to the shallow soils and groundwater conditions;

Provided visual/manual soil classifications in general accordance with ASTM D2487/2488 as well as soil profiles/logs for each of the borings;

Presented the results of our exploration and evaluation in an engineering report consisting of:

o The data developed during the study, including soil profiles;

o Interpretations of the site soil stratigraphy based on our boring results and review of the SCS Soil Survey;

o Provided depths to estimated seasonal high groundwater levels at the boring locations;

o Provided site preparation recommendations for the proposed roadway;

o Provided pavement design guidelines.

Subsurface Exploration

Power Auger Borings The subsurface exploration program included eleven power auger borings. The borings were positioned to provide a general overview of subsurface conditions along the proposed roadway alignments. The power auger borings were advanced to a depth of about 8 feet to explore the continuity of shallow subsurface conditions. The soil profiles from the roadway borings are illustrated on Figure 2 and 3. The power auger borings were performed by rotating a continuous flight auger into the ground using care not to excessively spin the auger or otherwise distort the soil stratigraphy. The auger was pulled and, as each soil type was exposed, its depth interval was recorded and representative samples taken for review in the laboratory. The power auger borings were conducted in general accordance with ASTM D 1452 (Standard Practice for Soil Investigation and Sampling by Auger Borings).


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Standard Penetration Test Borings

The subsurface exploration program for this study also included four Standard Penetration Test (SPT) borings positioned within proposed stormwater collection areas. The SPT borings were advanced to nominal depths of 20 feet using a conventional‐access drill rig. The soil profiles from the SPT borings are illustrated on Figure 4. The soil profiles for the SPT borings performed for the original site suitability study are shown on Figure 5. The SPT borings were conducted in general accordance with ASTM D1586 (Standard Test Method for Penetration Test and Split Barrel Sampling of Soils) using the rotary wash drilling procedure, where a clay‐water slurry (drill mud or drill fluid) was utilized to flush and stabilize the borehole. Standard Penetration Test sampling was performed at closely spaced intervals in the upper 10 feet and at 5‐foot intervals thereafter. After seating the sampler 6 inches into the bottom of the borehole, the number of blows required to drive the sampler one foot further with a standard 140 pound hammer dropped 30 inches is known as the "N" value or blowcount. The blowcount has been empirically correlated to soil properties. The recovered samples were placed into containers and returned to our office for visual review. Test Locations

The positioning of the borings was determined based on the provided conceptual site plan and requested test locations provided by Waldrop Engineering, and modified in the field based on site conditions. The test locations were located in the field using a hand‐held global positioning system (GPS) device. The test locations are illustrated on the site plan on Figure 1, which was derived from the conceptual site plan. The locations of the borings performed during the site suitability study are also shown on the attached Figure 1. The precision of the illustrated locations is limited to the methods utilized and is not comparable to that provided in a land survey of the property. Accordingly, the illustrated locations should be considered approximate. Laboratory Testing

The field soil boring logs and recovered soil samples were transported to our Tampa office from the project site. Following the completion of the field exploration activities, each soil sample was reviewed by a member of our technical staff in our Tampa, Florida soils laboratory, who assigned an engineering classification to the soil samples that were retrieved in the field exploration. The visual and tactile classification of the samples was performed in general accordance with ASTM D‐2488 (Standard Practice for Description and Identification of Soils (Visual‐Manual Procedure)) using the terminology in the current Unified Soil Classification System (ASTM D 2487).


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Five (5) samples were selected from the current borings for laboratory testing. The results of the laboratory testing were used to support our visual classifications and to assist in evaluation of the soils geotechnical engineering characteristics. The individual laboratory test results are presented with the soil boring profiles on Figures 2 through 4. Moisture Content – The moisture content is measured by weighing a sample of a selected material then drying it in a warm oven. Care is taken to use a gentle heat so as not to destroy any organic material. After heating, the sample is re‐weighed. The difference of the two weights is the amount of moisture removed from the sample. The weight of the moisture divided by the weight of the dry soil sample is the percentage by weight of the moisture. The testing was performed in general accordance with ASTM D2216 (Standard Test Method for the Determination of Water (Moisture) Content of Soil and Rock by Mass). Wash Gradation Test – The wash gradation test measures the percentage of a dry soil sample passing the No. 200 sieve. By definition in the Unified Soil Classification System, the percentage by weight passing the No. 200 sieve is the silt and clay content. This test was performed in general accordance with ASTM D 1140

(Standard Test Methods for Amount of Material Finer Than the No. 200 (75 m) Sieve). Organic Content ‐ The organic content test consists drying the soil sample, then heating it in a small furnace to a minimum temperature of 400 degrees Centigrade for 6 hours. The high heat burns off all organic material, leaving only the soil minerals. The difference in the weight prior to and after the burning is the weight of the organics. The weight of the organics divided by the weight of the dried soil is the percentage of the organics within a sample. The organic content testing procedure generally followed ASTM D 2974 (Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils). Atterberg Limits – The Atterberg liquid and plastic limits are performed on cohesive soils and measure the moisture contents at which a soil behaves as a viscous fluid and becomes plastic, respectively. The difference between the two limits is defined as the plasticity index. These moisture contents have been correlated to soil properties, such as suitability for fill and shrink‐swell tendency. ASTM D 4318 (Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils) was used as a guideline for this testing.

Subsurface Conditions

Hillsborough County Soil Survey

The United States Department of Agriculture (USDA) Natural Resources Conservation Service Web Soil Survey identifies Basinger, Holopaw, and Samsula soils, depressional (mapping unit 5) within the


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apparent wetland areas, and Malabar fine sand (mapping unit 27) and Myakka fine sand (mapping unit 29) as the main soil types in the apparent upland areas of the site. Basinger, Holopaw and Samsula soils, depressional, are nearly level and very poorly drained. They are in swamps and depressions on the flatwoods. Generally Basinger soil is along the exterior of swamps or in shallow depressions. Holopaw and Samsula soils are in the interior areas of the swamps or in deeper depressions. In most years, the undrained areas in this map unit are ponded for about 6 months. Permeability is rapid in the Basinger and Samsula soils. It is rapid in the surface and subsurface layer of Holopaw soil and moderately slow or moderate in the subsoil. The available water capacity is low in Basinger soil, low or moderate in Holopaw soil, and high in Samsula soil. Typically, the surface layer of Basinger soils is black fine sand about 7 inches thick. The subsurface layer, to a depth of about 28 inches, is gray fine sand. The subsoil, to a depth of about 42 inches, is brown and grayish brown fine sand. The substratum to a depth of about 80 inches is light brownish gray fine sand. Similar soils included in mapping, in some areas, have a surface layer or mucky fine sand, and it is more than 7 inches thick. Typically, the surface layer of the Holopaw is black mucky fine sand about 6 inches thick. The upper part of the subsurface layer, to a depth of about 12 inches is dark gray fine sand. The middle part, to a depth of about 42 inches, is light gray fine sand. The lower part, to a depth of about 52 inches, is grayish brown fine sand. The upper part of the subsoil, to a depth of about 64 inches, is grayish brown fine sand. The lower part to a depth of about 80 inches is gray, mottled sandy loam. Similar soils included in mapping, in some areas, have a black surface layer more than 10 inches thick. Typically, the upper part of the surface tiers of Samsula soil is black muck about 10 inches thick. The lower part, to a depth of about 34 inches, is dark reddish brown muck. The layer below the organic material, to a depth of about 40 inches, is black fine sand. The underlying material to a depth of about 80 inches is light brownish gray fine sand. Similar soil included in mapping, in some areas have organic material that is more than 51 inches thick. Malabar fine sand is nearly level and poorly drained. In most years, a seasonal high water table fluctuates from the soil surface to a depth of about 10 inches for 2 to 6 months. Permeability is rapid in the surface and subsurface layers, slow in the subsoil, and moderately rapid or rapid in the substratum. The available water capacity is very low or low. Typically, Malabar fine sand has a surface layer of dark gray fine sand about 4 inches thick, which is followed by light brownish gray fine sand. Brownish yellow fine sand is then penetrated from depths of 12 to 30 inches, and in turn overlies pale brown fine sand. From depths of 50 to 66 inches, gray mottled fine sandy loam is usually present, with grayish brown fine sand extending below to a depth of more than 80 inches.


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Myakka fine sand is nearly level and poorly drained. In its natural state, it is located on broad, low ridges between swamps and sloughs in pine flatwoods and in small areas on the upland ridge. The typical profile of the Myakka soil is characterized by 5 inches of very dark gray fine sand at the surface, which is followed by gray fine sand. From about 20 to 25 inches, black fine sand is present. A seam of reddish brown fine sand then occurs to a depth of 30 inches, and is in turn underlain by 8 inches of brownish yellow fine sand. Very pale brown fine sand is found below the brownish yellow fine sand, continuing to about 55 inches deep, where dark grayish brown fine sand is indicated to a depth in excess of 80 inches. In most years, the seasonal high water table in the natural state is at a depth of 6 to 18 inches. Permeability is rapid in the surface and subsurface layers, moderate or moderately rapid in the subsoil, and rapid in the substratum. Available water capacity is low. The stratigraphic conditions that are delineated by the USDA Soil Survey are not necessarily an exact representation of the soils that might underlie the site. The described conditions are, however, usually generally representative of the mapped area, and a good basis for evaluating the expected shallow soil and groundwater conditions. The soil survey mapping is based on interpretation of aerial maps with scattered shallow borings for confirmation. Accordingly, borders between mapping units are approximate and the change between mapping units may be transitional. Differences may also occur from the typical stratigraphy, and small areas of other similar and dissimilar soils may occur within the soil mapping unit. As such, there may be differences in the mapped description and the boring descriptions obtained for this report. In general, the above described Malabar fine sand stratigraphic profiles appear to be similar to the shallow soil conditions encountered in the borings performed throughout the upland areas of the anticipated development. Soil Boring Results

Soil profiles of the roadway and pond borings are presented on Figures 2 through 5. Our staff developed the soil profiles from the field boring logs and visual review of the recovered soil samples in our laboratory in general accordance with ASTM D2488 (Standard Practice for Description and Identification of Soils (Visual‐Manual Procedure)). The soils were grouped into strata, with each Stratum described in general accordance with the nomenclature in ASTM D2487 (Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)). The soil stratification boundaries may be approximate and the transition may be gradual. When the strata changed between sample intervals, its position was estimated. The SPT boring profiles include the SPT "N" values, and all boring profiles include the measured groundwater levels. Small variations may have been abbreviated or omitted for clarity. The general soil stratigraphy is summarized below. Please refer to the boring profiles for more detailed information. The majority of the borings initially encountered between 1 foot and 3 feet of very dark grayish brown slightly silty fine sand with abundant roots (Stratum 1), dark grayish brown to grayish brown and dark


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gray fine sand to slightly silty fine sand (Stratum 2) and/or gray fine sand (Stratum 3). Laboratory testing results on the Stratum 2 sample from boring location AB‐7 indicated a moisture content of 26.1%, an organic content of 1.9% and 5.5% passing the No. 200 sieve. Brown, yellowish brown, olive brown fine sand to slightly silty fine sand (Stratum 4) and/or light gray to white fine sand (Stratum 5) was penetrated below the Strata 1 through 3 soils. Laboratory testing of a Stratum 4 sample indicated 11.9% passing the No. 200 sieve. Boring locations AB‐2, AB‐4 through AB‐6, and AB‐9 through AB‐11 were terminated at 8 feet within Stratum 4. Borings AB‐1 and AB‐8 were terminated at 8 feet within Stratum 5. Below Stratum 5 at boring location AB‐7 and at boring locations PB‐1 through PB‐4, gray fine sand to clayey fine sand (Stratum 6) was encountered. The SPT borings were terminated at 20 feet within Stratum 6. Two (2) of the Stratum 6 samples indicated 6.2% and 8.2% passing the No. 200 sieve. At boring location AB‐3, a zone of very dark gray clayey fine sand (Stratum 7) was encountered between depths of approximately 7 feet and 8 feet. The Stratum 7 sample collected had a moisture content of 30.1%, a liquid limit of 24%, a plasticity index of 8 and 18.6 percent passing the No. 200 sieve. Groundwater Information

Water table readings were measured in the eleven roadway boreholes at depths varying from about 0.5 feet (boring AB‐8) to about 2.3 feet (boring AB‐11). At the pond borings, the groundwater was measured at depths of between about 1.7 feet and 2.2 feet.

The measured groundwater tables at the boring locations are presented in the attached boring profiles and Table 1 shown below. It should be noted that a seasonal effect will occur such that groundwater level fluctuations can be expected between the dryer winter and spring months as compared to the summer months or the wet season.


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Table 1 Estimated Normal Seasonal High Groundwater Table Levels

Boring Location

Ground Surface Elevation (feet NAVD

1988)

Measured Groundwater Table Reading (feet below

existing grade)

Groundwater Table Elevation (feet NAVD 1988)

Estimated Seasonal High Groundwater Table Elevation (feet NAVD 1988)

Date Groundwater Measured

AB‐1 25.0* 1.7 23.3 24.5 3/4/2014

AB‐2 25.17 1.3 23.9 24.7 3/4/2014

AB‐3 25.57 1.0 24.6 25.1 3/4/2014

AB‐4 25.81 1.4 24.4 25.3 3/4/2014

AB‐5 25.50 1.5 24.0 25.0 3/4/2014

AB‐6 25.02 1.3 23.7 24.5 3/4/2014

AB‐7 25.90 0.9 25.0 25.4 3/4/2014

AB‐8 26.36 0.5 25.9 25.9 3/4/2014

AB‐9 26.87 2.0 24.9 25.9 3/4/2014

AB‐10 26.95 1.8 25.2 26.0 3/4/2014

AB‐11 27.48 2.3 25.2 26.5 3/4/2014

PB‐1 26.62 2.2 24.4 25.6 3/5/2014

PB‐2 27.21 2.2 25.0 26.2 3/5/2014

PB‐3 27.03 1.8 25.2 26.0 3/4/2014

PB‐4 28.04 1.7 26.3 27.5 3/4/2014 *The ground elevations at boring location AB‐1 was estimated due to the boring being shifted east from the proposed location due to existing site conditions.

The groundwater levels presented in this report are the levels that were measured at the time of our field activities. Fluctuations should be anticipated. We recommend that the Contractor determine the actual groundwater levels at the time of the construction to determine groundwater impact on the construction procedures.

Geotechnical Evaluation

The following conclusions and recommendations are based on the project characteristics previously described, the data obtained in our field exploration and our experience with similar subsurface conditions. If final site planning is significantly different from previously described and as indicated in the report, or if subsurface conditions different from those disclosed by the borings are encountered during construction, we should be notified so that we might review the following recommendations in light of such changes. A general review of the project plans and specifications by our firm is suggested prior to bidding in order to check that these recommendations have been interpreted in accordance with our intent.


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In general, the results of the soil borings indicate that the soils should provide adequate support for residential structures on shallow foundations and standard pavement sections with nominal subgrade preparation. Further, with the exception of encountering isolated pockets of clayey soils (Stratum 7), the soils encountered at the test locations are considered acceptable for use as fill (borrow) to support residential structures and pavements/roadways with nominal soil management. Site Preparation Stripping and Grubbing – The initial step in routine site preparation for the roadway should be the complete removal of all topsoil, major root systems, stumps and other deleterious materials from beneath the roadway section, plus a distance of at least 5 feet beyond the proposed construction perimeter, such as the edge of pavements, sidewalks, etc. During site clearing and while excavating for site utilities, the exposed soils should be carefully observed for the presence of deleterious materials (e.g., organic soils, buried debris or near surface plastic clayey soils), which could be detrimental to pavement support. Accordingly, if questionable soils are identified in the pavement areas during construction, these soils should be evaluated by a geotechnical engineer for possible removal and replacement with properly compacted fill. Backfilling ‐ Backfill soil should be inorganic, non‐plastic granular soil with preferably less than 15% passing the No. 200 sieve (clean to slightly silty or slightly clayey sands) free of detrimental materials such as clay pockets/seams, debris, roots, rocks larger than 3 inches in greatest dimension, etc. Granular soils with between about 15% to 20% passing the No. 200 sieve (silty to clayey sands) are also acceptable provided the liquid limit does not exceed 35 to 40 and the plasticity index is less than 10 to 15. The on‐site soils visually appear to meet this requirement. The backfill should be placed in level lifts not to exceed 9 to 12 inches loose thickness, depending upon compactor size and performance. The backfill should be compacted to a minimum density of 98% of the modified Proctor maximum dry density as determined by AASHTO T‐180. In‐place density tests should be performed on each lift by an experienced engineering technician working under the direction of a licensed Geotechnical Engineer to verify that the recommended degree of compaction has been achieved. Subgrade Proofrolling and Compaction – After the checking for satisfactory initial stripping operations by a Geotechnical Engineer or his representative, the pavement areas should be proofrolled using a large vibratory roller having a minimum static drum weight of 5 to 10 tons. The purposes of the proofrolling will be to help detect any additional areas where unsuitable soils may be present, as well as to uniformly densify the near‐surface sandy soils. Materials which yield excessively during the proofrolling should be examined and possibly undercut and replaced with well‐compacted fill. It is important that the proofrolling utilize a large, heavy vibratory roller to achieve the desired depth of effect. Proofrolling of the roadway areas should consist of at least 10 passes and should be observed by a Geotechnical Engineer or his representative. The compactor should travel at a slow walking pace.


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Proofrolling should occur at the final cut or existing stripped grade elevation, whichever is lower. Care should also be used when operating the compactor near any existing structures to avoid transmission of vibrations that could cause settlement or disturb occupants. Proofrolling of pavement areas should continue beyond the minimum number of passes until the stripped surface has attained a minimum of 98% of the soil’s modified Proctor maximum dry density as determined by AASHTO T‐180, or as required by Hillsborough County. Depending upon pavement grades, the stripped subgrade may need to be compacted to a density of no less than 98% of the modified Proctor value. The subgrade soils within a distance of 12 inches below the stabilized subgrade should be compacted per Hillsborough County specifications. In‐place density tests should be performed by an experienced geotechnical engineering technician working under the direction of a licensed Geotechnical Engineer to verify the required degree of compaction. Density testing frequency should follow Hillsborough County specifications or at least 1 test per 500 linear feet of pavement area. It may be necessary to adjust the moisture content of the soil

to facilitate compaction. A moisture content within 2 percentage points of the optimum indicated by the modified Proctor test is recommended. Fill Placement – After the stripped site has been proofrolled and accepted by the Geotechnical Engineer, fill required to bring the pavement areas to final grade may be placed and properly compacted. Fill should be inorganic, non‐plastic granular soil with preferably less than 15% passing the No. 200 sieve (clean to slightly silty or slightly clayey sands) free of detrimental materials such as clay pockets/seams, debris, roots, rocks larger than 3 inches in greatest dimension, etc. Granular soils with between 15% to 20% passing the No. 200 sieve (silty to clayey sands) are also acceptable provided the liquid limit does not exceed 35 to 40 and the plasticity index is less than 10 to 15. The fill should be placed in level lifts not to exceed 12 inches loose thickness. The fill should be compacted per Hillsborough County specifications. In‐place density tests should be performed on each lift by an experienced engineering technician working under the direction of a licensed Geotechnical Engineer to verify that the recommended degree of compaction has been achieved. We suggest the following minimum testing frequency, per layer of fill placed: one test per 500 linear feet of pavement area or as required by Hillsborough County. Pavement Design Recommendations Waldrop proposed a pavement section including 12‐inches of compacted subgrade soil with a minimum LBR value of 20. Per the Hillsborough County Transportation Technical Manual for Subdivisions and Site Development Projects, September 1, 2009, subgrades below crushed concrete shall have a minimum LBR of 40. As a guideline, based on past experience, the existing on‐site sands are anticipated to have an LBR value on the order of about 20 or greater. However, testing of sandy soils should be performed to determine actual LBR values. If necessary, in order to increase the bearing value, limerock, crushed


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concrete, low plasticity clayey sands or another acceptable product would need to be blended with these sands. The base proposed by Waldrop consists of 6 inches of crushed concrete. The crushed concrete product will be acceptable provided a minimum of 18 inches of separation is provided between the bottom of base and seasonal high groundwater levels. It is recommended the base material be compacted to a minimum of 100% of the soil’s maximum dry density as determined by AASHTO T‐180 (modified Proctor) with an LBR value of 150, which is the Hillsborough County minimum requirement. The gradation of the crushed concrete should meet the requirements within the Hillsborough County Transportation Technical Manual for Subdivisions and Site Development Projects. Before paving, the base should be inspected by the Engineer of Record and the PGMD Inspector. It is our understanding the flexible pavement surface course will consist of 1.25 inches of Type S‐I asphaltic concrete below 0.75 inches of Type S‐III asphaltic concrete material. The Hillsborough County Transportation Technical Manual for Subdivisions and Site Development Projects, September 1, 2009 states superpave asphalt is required on all roads that are within Hillsborough County jurisdiction. Similar superpave products include SP 9.5 and SP 12.5. The manual should be reviewed for superpave asphalt requirements. Underdrain Requirements A minimum separation of 18 inches should be provided between the bottom of the crushed concrete bases and seasonal high groundwater levels, unless an underdrain system is installed to control groundwater levels. CRA can review paving and grading plans once finalized and provide specific locations for underdrains, if requested. Borrow Soil Suitability

The majority of the soils encountered by the borings (Strata 2 through 5, SP to SP‐SM, as well as portions of Stratum 6, SP/SC soil types) can be categorized as relatively clean to slightly silty to slightly clayey fine sand based on the Unified Soil Classification System (USCS). These soil types will be suitable for reuse as fill with minimal processing to adjust water contents. Although the Stratum 1 soils were classified as slightly silty fine sand (SP‐SM), based on the abundant roots and organic fines contained within the collected samples, it is our opinion that Stratum 1 should only be considered for use in landscaping areas. Portions of Strata 6, as well as the Stratum 7 soil types, were considered to be a clayey sand, classified as SC according to the USCS system designation, would generally have in excess of 12% and will most likely exhibit low to moderate plasticity characteristics. Clayey fine sand is considered suitable for pavement and structural fill provided that the plasticity characteristics are acceptable. These soils are considered


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usable for more select pavement and structure fill where the silt/clay content is less than 15% to 20%, liquid limit does not exceed 35 and the plasticity index is less than 10 to 15. Based on limited laboratory testing results and visual inspection, the Strata 6 soil types will either be non‐plastic or possess lower plasticity soils where the clay content is reduced and is usually within limits suitable for placement in structure or pavement areas, while the Stratum 7 soil type will possess higher clay content and may be more difficult to work with as fill. CRA recommends on‐site monitoring during pond/borrow pit excavations of the silty to clayey sand deposits to visually inspect the soils and to determine the need for laboratory testing on select samples for fill use suitability. Careful moisture control and earthwork management of the clayey sand will also be required to produce an acceptable product for placement and compaction. These soil types will probably be excavated from below the water table and will generally possess elevated moisture contents that make them unsuitable for immediate placement and compaction. The soils with elevated clay fines will also require proper earthwork management to reduce moisture contents to levels suitable for placement and compaction. Limitations

Our professional services have been performed, our findings obtained, and our opinions prepared in accordance with generally accepted geotechnical engineering principles and practices. All testing was performed in general accordance with recognized methods and guidelines; minor procedural variations that are not expected to affect the conclusions reached herein may have been taken. CRA is not responsible for the conclusions, opinions or recommendations made by others based on these data. The scope of the study was intended to evaluate subsurface soil and groundwater conditions within the specific development areas based on the provided conceptual site plan. The analysis and opinions submitted in this report are based upon the data obtained from the soil borings performed at the actual field locations. The scope of our services does not include any environmental assessment or investigation for the presence or absence of hazardous or toxic materials in the soil, groundwater, or surface water within or beyond the site studied. Any statements in this report regarding odors, staining of soils, or other unusual conditions observed are strictly for the information of our client.


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Closure

Conestoga‐Rovers & Associates is pleased to have the opportunity to submit this geotechnical report for the proposed development. We look forward to continuing our participation in the design and construction process as the project proceeds. Should you have any questions or require additional information, please do not hesitate to contact the undersigned. Sincerely, CONESTOGA‐ROVERS & ASSOCIATES, INC. FL Engineering Business No. 9931 FL Geology Business No. GB711

Scott L. Linteau, P.E. Senior Geotechnical Engineer Florida License No.: PE 68363

Andres F. Alberdi, P.E. Principal Florida License No.: PE 42449

SLL/AFA/cp/Azan‐01 Encl.: Figure 1 Boring Location Map

Figures 2 and 3 Roadway Auger Boring Profiles Figure 4 Pond SPT Boring Profiles Figure 5 Site Suitability Study ‐ SPT Boring Profiles

cc: Mr. Trent Stephenson, Waldrop Engineering (via electronic mail) Distribution: Addressee – (2) Original Bound

Braun Property report -

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