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Home My WebLink AboutReport Of Geotechnical ExplorationGFA INTERNATIONAL FLORIDA'S LEADING ENGINEERING SOURCE Report of Geo`technical Exploration Proposed 3-Level Residence 4876 Watersong Way (Lot 50 Watersong) St. Lucie County, Florida May 11, 2017 GFA Project No.: 17-1203.00 For: Coastal Construction and Design D.oDggc :• ''/y' I' c 4:�bpapOpG G:� . 4R�RPaRpD9ppDbpR'� �RY4nHp4Gb.nagpUGL'. fI' ..+ •'+ ,+ � . Gn'tCnbOCOb..QtlO¢b4tlpQDbpG b...tlaQaapp....4I,C pnUtlnbp. aO C,. ..nb.tlb.QO �.....CCpncU t.uu �ngbpnQnppatlOppnHDQ4bnOQ ��,� '+ODDGpROp.Unpq., �...' Z . 'S.`-� +-.,, b p.btlODabnpae.OatlaD. 'Inan.btl.cDntrggq�CCG� ipp4ppODDODbOpneDOgbp =90OpQ444na4pRp4ppgnr�¢zt.,: U ''CC11 � �. 'A"r ja.�ti•" � � `� �¢pppatlbDpppaODpOnO p� a¢OQQpppnDpppnp¢aDnUtl4gr.0 i::�C DDOROtltlbDtlD.Dtlf CCDtlatlODDObpapabDUDpG p4ggnn. G:."U• .. '�pjjRnb.p e��D pC aDDOntlaQDbOpDDnpapppLDbbppp4nunRL. 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G QCGbbEbC507bDpr.QbnpbggOCD.Q➢pp4f_.B r ,. +r .r.. .7 ., a. c,rq .�.. r. r,n R'A4abpi5'u.,,.•-71 ' Du ur -1 c�a pRu Qnnanuu:++. . n..tlQaRacr ifbDDODDDOb4L pDnOQpp➢04.np p �uUU,n0 Qb 4pDOtlpOOpCr. n'gaD.nCHObD4b.D.¢U,a y4DOEbDDbpDbO.DDObO`. �,��J��\1�vy,�f\��7)� c cc epDuvpcDpn.o �c./ ncnpoDau¢cn� � � Florida's Leading Engineering Source Environmental - Geotechnical • Construction Materials Testing • Threshold and Special Inspections • Plan Review & Code Compliance May 11, 2017 Coastal Construction and Design Attention: Mario Arbucci 1812 NW Old Oak Terrace Jensen Beach, Florida 34957 Site: Proposed 3-Level Residence 4876 Watersong Way (Lot 50 Watersong) St. Lucie County, Florida GFA Project # 17-1203.00 Dear Mr. Arbucci: GFA International, Inc. (GFA) has completed the subsurface exploration and geotechnical engineering evaluation for the above -referenced project in accordance with the geotechnical and engineering service agreement for this project. The scope of services was completed in accordance with our Geotechnical Engineering Proposal (17-1203.00) dated April 25th, 2017, planned in conjunction with and authorized by you. EXECUTIVE SUMMARY The purpose of our subsurface exploration was to classify the nature of the subsurface soils and general geomorphic conditions and evaluate their impact upon the proposed construction. This report contains the results of our subsurface exploration at the site and our engineering interpretations of these, with respect to the project characteristics described to us including providing recommendations for site preparation and the design of the foundation system. Based on conversations with the client, the project consists of constructing a three-story residence. The residential structure (or portion thereof) will be located east of the Coastal Construction Control Line (CCCL) and therefore a pile supported foundation is required. GFA assumes that the residence will be three levels, or will be elevated above a lower level garage that will have walls and ground floor slab of frangible breakaway design. Based on a Boundary & Topographic Survey prepared by Arnold Surveying, Inc. (dated 4/8/2017), the current grade at the location of the proposed residence was about +5 to +6 feet NAVD. Assuming the proposed house will have a grade about equal to the nearby residences, about 1 foot of fill will be required. to achieve final grade. The recommendations provided herein are based upon the above considerations. If the project description has been revised, please inform GFA. International so that we may review our recommendations with respect to any.modifications. A total of two (2) standard penetration test (SPT) borings to depths of approximately thirty-five (35) feet below ground surface (BGS) were completed for this study. 521 NW Enterprise Drive • Port St. Lucie, Florida 34986 • (772) 924.3575 • (772) 924-3580 (fax) • www.teamgfa.com OFFICES THROUGHOUT FLORIDA Proposed 3-Level Residence Geotechnical Report Lot 50 Watersong, St. Lucie County, FL May 11, 2017 GFA Project No. 17-1203.00 Page 2 of 13 The subsurface soil conditions encountered at this site generally consist of medium dense sand (SP) to 13%2 feet with an organic silt (muck) (PT) layer from 8 to 9 feet, sand to sandy silt (SP,SM,ML) from 13Y2 feet to 18Y2 feet, medium dense to very dense sand (SP) from 18%2 to 23Y2 feet, and then dense to very dense sand with trace cemented sand (SP) from 23Y2 feet to the boring termination depths. Asphalt was encountered in boring SPT-2 .from 2 to 2%2.feet. Please refer to Appendix D - Record of Test Borings for a detailed account of each boring and sounding. GFA recommends that the proposed residence be supported using a deep foundation system consisting of augered cast -in -place (ACIP) piles. Based on our analysis, GFA has estimated that a 14 or 16-inch-diameter ACIP pile installed to a depth of 25 feet below grade existing grade can provide a maximum allowable axial' compressive capacity of 40 tons and a maximum tension capacity of 6 tons. The pile installation length is based on installing the piles at site grade (grade about 1 foot above the adjacent roadway) existing at time of drilling. If additional fill will be required to raise the site to achieve final grade, the piles will be longer according to the depth of fill added. Very dense/hard soils may be encountered with auger refusal. The piles may be installed prior to achieving the required depth if there is auger refusal. Refusal is defined as a minimum of 3 minutes drilling for 3 inches or less auger penetration into rock. GFA also recommends that the ground level frangible walls and floor slab be pile supported due to the presence of compressible organic subgrade soils (muck). If a pile foundation system is not used, then the soils will likely compress and cause settlement problems and GFA anticipates long term settlement and differential settlement on the order of 1 to 2 inches with subsequent cracking, distress, distortion, and other related problems such as utility connects breaking with subsequent damage. Maintenance, and possibly occasional renovations, could be required. If such performance is acceptable, the client and property ownership must acknowledge the risks involved and agree that the result is acceptable. For the ground supported frangible walls, an allowable bearing capacity of 2,500 psf may be used for shallow footing foundation design. The subgrade soils should be improved with compaction from the stripped grade prior to constructing the foundation pads and footing excavations. The top 2 feet below stripped grade should be compacted to a minimum of 95% density prior to placing fill to achieve final grade. Fill (including stemwall backfill) should be placed in 12-inch lifts and compacted to achieve a minimum 95% density. After excavation for footings, the subgrade to a depth of 2 feet below bottom of footings should be compacted to achieve a minimum 95% density. Scour elevations used in pile calculations are those provided by the Florida DEP for coastal construction, but may not be adequate for actual scour elevations in hurricane(s) event(s) that exceed the DEP assumptions and cause lower scour elevations. Therefore, GFA analysis is limited to that provided by the DEP scour elevation, and scour analysis is not included in our scope of work. (1. [A Proposed 3-Level Residence Geotechnical Report Lot 50 Watersong, St. Lucie County, FL May 11, 2017 GFA Project No. 17-1203.00 Page 3 of 13 We appreciate the opportunity to be of service to you on this project and look forward to a continued association. Please do not hesitate to contact us if you have any questions or comments, or if we may further assist you as your plans proceed. e\1008BY0lpOB Rest�8�� & 9b�+ft"�.d. n Number 4930 o 606 o 4 aVI Id W. Moler nY8 fteer F675 Copies. fig, RIA'see n 01Iie, E.I. jwae Manager r J (I [A Proposed 3-Level Residence Geotechnical Report Lot 50 Watersong, St. Lucie County, FL. May 11, 2017 GFA Project No. 17-1203.00 Page 4 of 13 TABLE OF CONTENTS 1.0 INTRODUCTION.....................................................:......................................:....................5 1.1 Scope of Services.......................:....................................................................................5 1.2 Project Description...........................................................................................................5 2.0 OBSERVATIONS.................................................................................................................6 2.1 Site Inspection .........................................................................................................6 2.2 Field Exploration............................................................................:.................................6 2.3 Laboratory Analysis..........................................................................................................6 2.4 Geomorphic Conditions....................................................................................................6 2.5 Hydrogeological Conditions..............................................................................................7 3.0 ENGINEERING EVALUATION AND RECOMMENDATIONS..............................................7 3.1 Foundation Recommendations - General.........................................................................7 3.2 Pile Foundation....................................:...........................................................................8 3.3 Pile Installation..................................................................................................................9 3.4 Vibration Monitoring.......................................................................................................10 3.5 Design of Footings (Ground Level Frangible Walls).......................................................10 3.6 Ground Floor Slab (Frangible)........................................................................................10 3.7 Site Preparation.............................................................................................................11 3.8 Excavation Conditions....................................................................................................12 4.0 REPORT LIMITATIONS.....................................................................................................12 5.0 BASIS FOR RECOMMENDATIONS..........................................................:........................13 Appendix A - Vicinity Map Appendix B - Test Location Plan Appendix C - Notes Related to Borings Appendix D - Record of Test Borings Appendix E - Discussion of Soil Groups C,FA Proposed 3-Level Residence Lot 50 Watersong, St. Lucie County, FL GFA Project No. 17-1203.00 1.0 INTRODUCTION 1.1 Scope of Services Geotechnical Report May 11, 2017 Page 5 of 13 The objective of our geotechnical services was to collect subsurface data for the subject project, summarize the test results, and discuss any apparent site conditions that may have geotechnical significance for building construction. The following scope of services are provided within this report: Prepare records of the soil boring logs depicting the subsurface soil conditions encountered during our field exploration. 2. Conduct a review of each soil sample obtained during our field exploration for classification and additional testing if necessary. 3. Analyze the existing soil conditions found during our exploration. with respect to foundation support for the proposed structure. 4. Provide recommendations with respect to foundation support of the structure, including allowable soil -bearing capacity, bearing elevations, and foundation design parameters. 5. Provide criteria and site preparation procedures to prepare the site for the proposed construction. . 1.2 Project Description Based on conversations with the client, the project consists of constructing a three-story residence. The residential structure (or portion thereof) will be located east of the Coastal. Construction Control Line (CCCL) and therefore a pile supported foundation is required. GFA assumes that the residence will be three levels, or will be elevated above a lower level garage that will have walls and ground floor slab of frangible breakaway design. Based on a Boundary & Topographic Survey prepared by Arnold Surveying, Inc. (dated 4/8/2017), the current grade at the location of the proposed residence was about +5 to +6 feet NAVD. Assuming the proposed house will have a grade about equal to the nearby residences, about 1 foot of fill will be required to achieve final grade. We assume the residence will have typical construction, and be supported on columns terminating on pile caps slightly below the ground level elevation and top of piles (bottom of pile caps) would be at about existing grade. We have not received any information regarding structural loads. For the foundation recommendations presented in this report we assumed the maximum column load will be 75 kips and the maximum wall loading will be 4 kips per linear foot. The recommendations provided herein are based upon the above considerations. If the project description has been revised, please inform GFA International so that we may review our recommendations with respect to any modifications. C,FA Proposed 3-Level Residence Lot 50 Watersong, St Lucie County, FL GFA Project No. 17-1203.00 2.0 OBSERVATIONS 2.1 Site Inspection Geotechnica/ Report May 11, 2017 Page 6 of 13 The project site was generally clear and grassy. The site was about even with the adjacent roadway. The Atlantic Ocean bordered the east side of the property. 2.2 Field Exploration A total of two (2) standard penetration test (SPT) borings to depths of approximately thirty-five (35). feet below ground surface (BGS) were completed for this study. The locations of the borings performed are illustrated in Appendix B: "Test Location Plan". The Standard Penetration Test (SPT) method was used as the investigative tools within the borings. SPT tests were performed in substantial accordance with ASTM Procedure D-1586, "Penetration Test and Split - Barrel Sampling of Soils". The SPT test procedure consists of driving a 1.4-inch I.D. split -tube sampler into the soil profile using a 140-pound hammer falling 30 inches. The number of blows per foot, for the second and third 6-inch increment, is an indication of soil strength. The soil samples recovered from the soil borings were visually classified and their stratification is illustrated in Appendix D: "Record of Test Borings". It should be noted that soil conditions might vary between ,the strata interfaces, which are shown. The soil boring data reflect information from a specific test location only. Site specific survey staking for the test locations was not provided for our field exploration. The indicated depth and location of each test was approximated based upon existing grade and estimated distances and relationships to obvious landmarks. The boring -depths were confined to the zone of soil likely to be stressed by the proposed construction and knowledge of vicinity soils. 2.3 Laboratory Analysis Soil samples recovered from our field exploration were returned to our laboratory where they were visually examined in general accordance with ASTM D-2488. Samples were evaluated to obtain an accurate understanding of the soil properties and site geomorphic conditions. After a thorough visual examination of the recovered site soils, no laboratory testing was deemed necessary. Bag samples of the soil encountered during our field exploration will be held in our laboratory for your inspection for 30 days and then discarded unless we are notified otherwise in writing. The recovered samples were not examined, either visually or analytically, for chemical composition or environmental hazards. GFA would be pleased to perform these services for an additional fee, if required. 2.4 Geomorphic Conditions The geology of the site as mapped on the USDA Soil Survey website consists of Canaveral fine sand, 0 to 5 percent slopes (10). These are sandy soils and organic soils are not indicated. It should be noted that the Soil Survey generally extends to a maximum depth of 80 inches (approximately 6% feet) below ground surface and is not indicative of deeper soil conditions. (I FA Proposed 3-Level Residence Geotechnica/ Report Lot 50 Watersong, St. Lucie County, FL May 11, 2017 GFA Project No. 17-1203.00 Page 7 of 13 Boring logs derived from our field exploration are presented in Appendix D: 'Record of Test Borings". The boring logs depict the observed soils in graphic detail. The Standard Penetration Test borings indicate the penetration resistance, or N-values logged during the drilling and sampling activities. The classifications and descriptions shown on the logs are generally based upon visual characterizations of the recovered soil samples. All soil samples reviewed have been depicted and classified in general accordance with the Unified Soil Classification System, modified as necessary to describe typical Florida conditions. See Appendix E: "Discussion of Soil Groups", for a detailed description of various soil groups. The subsurface soil conditions encountered at this site generally consist of medium dense sand (SP) to 13'h feet with an organic silt (muck) (PT) layer from 8 to 9 feet, sand to sandy silt (SP,SM,ML) from 13% feet to 18Y2 feet, medium dense to very dense sand (SP) from 18%2 to 23% feet, and then dense to very dense sand with trace cemented sand (SP) from 23%2 feet to the boring termination depths. Asphalt was encountered in boring SPT-2 from 2 to 2% feet. Please refer to Appendix D - Record of Test Borings for a detailed account of each boring and sounding. 2.5 Hydrogeological Conditions On the dates of our field exploration, the groundwater table was encountered at depths ranging from approximately 5.1 to 5.6 feet below the existing ground surface. The groundwater table will fluctuate seasonally depending upon local rainfall and other site specific and/or local influences including ,the water level in the nearby Atlantic Ocean with tidal influences. Brief ponding of stormwater may occur across the site after heavy rains. No additional investigation was included in our scope of work in relation to the wet seasonal high groundwater table or any existing well fields in the vicinity. Well fields may influence water table levels and cause significant fluctuations. If a more comprehensive water table analysis is necessary, please contact our office for additional guidance. 3.0 ENGINEERING EVALUATION AND RECOMMENDATIONS 3.1 Foundation Recommendations - General The residential structure will be located east of the Coastal Construction Control Line (CCCL) and therefore a pile supported foundation is required. Frangible ground floor slabs and ground level walls may be pile supported or supported on footings in accordance with rules and regulations (to be determined by others). GFA also recommends that the ground level frangible walls and floor slab be pile supported due to the presence of compressible organic subgrade soils (muck). If a pile foundation system is not used, then the soils will likely compress and cause settlement problems and GFA anticipates long term settlement and differential settlement on the order of 1 to 2 inches with subsequent cracking, distress, distortion, and other related problems such as utility connects breaking with. subsequent damage.. Maintenance, and possibly occasional renovations and reconstruction, could be required. If such performance is acceptable, the client and property ownership must acknowledge the risks involved and agree that the result is acceptable. C,FA Proposed 3-Level Residence Lot 50 Watersong, St. Lucie County, FL GFA Project No. 17-1203.00 3.2 Pile Foundation The following is design parameters GFA used for pile recommendations: Geotechnical Report May 11, 2017 Page 8 of 13 ➢ For CCCL construction, the FDEP has established a 100-year storm elevation (bottom of lowest structural member) . of +17.0 to +17.9 feet NGVD (depends on location) for structures within St. Lucie County. ➢ For CCCL construction, the FDEP has established a 106-year storm erosion elevation (design scour elevation) of +2.7 feet NGVD for all of St. Lucie County. ➢ A loss of soil support between the bottom of lowest structural member and design scour elevation (+2.7 feet NGVD) was includedin compressive, tensile, and lateral pile capacity analyses. ➢ We assume the residence will have typical construction, and be supported on columns terminating on pile caps slightly below the ground floor elevation. We assume that pile caps slightly below the ground level elevation and top of piles (bottom of pile caps) would be at about existing grade. At this time, GFA recommends the deep foundation to consist of augered cast -in -place piles (ACIP). Additional lateral capacity may be attained by utilizing inclined piles. We assumed that the piles will have a minimum of 1% steel reinforcement for the analyses. ACIP pile installation procedures should be performed in accordance with the guidelines presented in the latest edition of the Deep Foundations Institute's Augered Cast -In -Place Pile Manual. The lateral capacity and pile top deflection were calculated using the commercially available L-pile 4.0 software. A summary of pile capacities ACIP piles is presented in the following table. Pile Recommendations For All Pile Supported Structures Maximum Nominal Pile Top Recommended Pile Pile Pile Pile Lateral Pile Elevation Pile Tip Lengths Compression Tension Capacity Recommended Diameter (NGVD)- Elevation (ft)** Capacity Ca aci (Tons)*** Grout Strength 0.5 Tons (Free Head) 14" or 1.25 Tons 16" Unknown Unknown 25 40 Tons 6 Tons Fixed Head 5000 psi *Pile top elevation assumed at, or more than, +4 feet NGVD for analyses. **From ground surface existing at time of drilling. ***For calculated pile top deflection of inches at top of pile elevation. The pile installation length is based on installing the piles at site grade (grade about even with the adjacent roadway) existing at time of drilling. If additional fill will be required to raise the site to achieve final grade, the piles will be longer according to the depth of fill added. Very dense/hard soils may be encountered with auger refusal. The piles may be installed prior to achieving the required depth if there is auger refusal. Refusal is defined as a minimum of 3 minutes drilling for 3 inches or less auger penetration into rock. GFA assumed that the piles will have a minimum of 1% steel reinforcement for the analyses. Augercast piles should be reinforced over their entire length for tension capacity. The reinforcement shall be as designed by the Structural Engineer. C,FA Proposed 3-Level Residence Lot 50 Watersong, St. Lucie County, FL GFA Project No. 17-1203.00 Geotechnical Report May 11, 2017 Page 9 of 13 If piles of lesser or greater capacities than those mentioned in the table above are required, GFA would be pleased to provide further recommendations upon request. The following additional notes are applicable to the pile design: Structural stresses in the piles may impose a more severe limitation on the design capacity; therefore, we recommend the allowable stresses be verified for the selected pile section. The pile reinforcement is sufficiently embedded in the pile cap so as to afford a fixed end connection if required. 3.3 Pile Installation Pile design and installation shall be in accordance with the applicable sections of the Florida Building Code and other applicable federal, state and local requirements. In addition, piles should be installed in accordance with the following: Pile Length: The proposed 1 4-inch-d ia meter piles should be installed as determined by the inspecting Geotechnical Engineer. 2. Spacing - Piles installed in groups should be spaced at a center -to -center distance of not less than 3 pile diameters. 3. Plan Location - The center of the top of any pile at cut-off should be displaced laterally no more than 3 inches from the position shown on the plans. This applies to both single piles and piles installed in groups. 4. Vertical Alignment - The vertical alignment of the piling should not deviate from the plumb by more than 1/4 inch per foot of length. 5. Reinforcing Cage Positioning - The top of the reinforcing cages installed in the piling should not be more than 6 inches above and no more than 3 inches below the positions shown in the plans. The reinforcing cages should be positioned concentrically within the grouted pile shaft. The grout cover over longitudinal reinforcing bars should not be less than 3 inches. Reinforcing centralizers shall be placed at maximum spacing of 15 feet at the lower portion of the pile and at 5 feet from the cage's top. 6. Adjacent Piles - A minimum time period of 12 hours should be specified for the installation of piles located within 5 feet, center -to -center, of each other. 7. . Grout Factor - The minimum acceptable grout factor (i.e. actual grout volume divided by theoretical grout volume) should be 1.1. 6FA Proposed 3-Level Residence Lot 50 Watersong, St. Lucie County, FL GFA Project No. 17-1203.00 3.4 Vibration Monitoring Geotechnical Report May 11, 2017 Page 10 of 13 The proposed construction will be within close proximity to residential structures and roadways that maybe susceptible to damage from vibration generated at the site. We recommend that during all aspects of construction, the bordering landmarks be monitored using a .seismograph to determine the extent of vibration absorption that these features will be subject to. The seismograph used to monitor at this site should have the capability to measure ground velocities along vertical, transverse, and longitudinal axes. The project structural engineer should establish allowable ground velocities that the bordering facilities can safely withstand without any damage. 3.5 Design of Footings (Ground Level Frangible Walls) Footings may be designed using an allowable soil bearing pressure of 2,500 psf. Shallow foundations should be embedded a minimum of 12 inches below final grade. This embedment shall be measured from. the lowest adjacent grade. Isolated column footings should be at least 24 inches in width and continuous strip footings should have a width of at least 16 inches regardless of contact pressure. Once site preparation has been performed in accordance with the recommendations described in this report, the soil should readily support the proposed structure resting on a shallow foundation system (See Executive Summary for potential problems with ground supported structures and slabs). All footings and columns should be structurally separated from the floor slab, as they will be loaded differently and at different times, unless a monolithic mat foundation is designed. 3.6 Ground Floor Slab (Frangible) The ground floor slabs may be supported directly on the existing grade or on granular fill following the foundation site preparation and fill placement procedures outlined in this report. For purposes of design, a coefficient of subgrade modulus 150 pounds per cubic inch may be used. The ground floor slab should be structurally separated from all walls and columns to allow for differential vertical movement. (See Executive Summary for potential problems with ground supported structures and slabs). Water vapor is likely to rise through the granular fill and condense beneath the base of the floor slab. If moisture entryinto the floor slab is not desirable, an impermeable membrane should be installed at the slab bottom - subgrade interface. 6 FA Proposed 3-Level Residence Geotechnical Report Lot 50 Watersong, St. Lucie County, FL May 11, 2017 GFA Project No. 17-1203.00 Page 11 of 13 3.7 Site Preparation GFA recommends the following compaction requirements for this project: ➢ Proof Roll......................................................................95% of a Modified Proctor ➢ Building Pad Fill............................................................95% of a Modified Proctor ➢ Footings........................................................................95% of a Modified Proctor The compaction percentages presented above are based upon the maximum dry density as determined by a "modified proctor" test (ASTM D-1557). All density tests should be performed to a depth of 2 feet below stripped surface and 2 feet below bottom of footings (See Executive Summary for potential problems with ground supported structures and slabs). All density tests should be performed using the nuclear method (ASTM D-2922), the sand cone method (ASTM D-1556), or Hand Cone Penetrometer (HCP) tests. Our recommendations for preparation of the site are presented below. This approach to improving and maintaining the site soils has been found to be successful on projects with similar soil conditions. Initial site preparation should consist of performing stripping (removing surface vegetation, near surface roots, and other deleterious matter) and clearing operations. This should be done within, and to a distance of five (5) feet beyond, the perimeter of the proposed building footprint (including exterior isolated columns). Foundations and any below grade remains of any structures that are within the footprint of the new construction should be removed, and utility lines should be removed or properly abandoned so as to not affect structures. If the demolished residence had a pile foundation, GFA must be notified as the recommendations may change. 2. Following site stripping and prior the placement of any fill, areas of surficial sand (not exposed limestone) should be compacted ("proof rolled") and tested. We recommend using a steel drum vibratory roller with sufficient static weight and vibratory impact energy to achieve the required compaction. Density tests should be performed on the proof rolled surface at a frequency of not less than one test per 2,500 square feet, or a minimum of three (3) tests, whichever. is greater. Areas of exposed intact limestone shall be visually confirmed by the project geotechnical engineer prior to fill placement, in lieu of proof rolling. 3. Fill material may then be placed in the building pad as required. The fill material should be inorganic (classified as SP, SW, GP, GW, SP-SM, SW-SM, GW-GP, GP -GM) containing not more than 5 percent (by weight) organic materials. Fill materials with silt/clay-size soil fines in excess of 12% should not be used. Fill should be placed in lifts with a maximum lift thickness'not exceeding 12-inches. Each lift should be compacted and tested prior to the placement of the next lift. Density tests should be performed within the fill at a frequency of not less than one test per 2,500 square feet per lift in the building areas, or a minimum of three (3) tests per lift, whichever is greater. 4. For any footings bearing on a limestone formation, the bottom of all footing excavation shall be examined by the engineer / geologist or his representative to determine the condition of the limestone. The limestone shall be probed for voids and loose pockets. of sand. Such GFA Proposed 3-Level Residence Lot 50 Watersong, St. Lucie County, FL GFA Project No. 17-1203.00 Geotechnical Report May 11, 2017 Page 12 of 13 areas shall be cleaned to depth of 3 times the, greatest horizontal dimension and backfilled with lean concrete. 5. For footings placed on structural fill or compacted native granular soils, the bottom of all footings shall be tested for compaction and examined by the engineer / geologist or his representative to determine if the soil is free of organic and/or deleterious material. Density tests should be performed at a frequency of not less than one (1) density test per each isolated column footing and one (1) test per each seventy five (75) lineal feet of wall footings. 6. Upon completion of production pile installation and pile cap construction, the pile caps should be backfilled in 6 to 8 inch thick lifts and compacted to at least 95% of the modified Proctor maximum dry density (ASTM D 1557). 7. The contractor should take into account the final contours and grades as established by the plan when executing his backfilling and compaction operations. Using vibratory compaction equipment at this site may disturb adjacent structures. We recommend that you monitor nearby structures before and during proof -compaction operations. A representative of GFA International can monitor the vibration disturbance of adjacent structures. A proposal for vibration monitoring during compaction operations can be supplied upon request. 3.8 Excavation Conditions In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its "Construction Standards for Excavations, 29 CFR, part 1926, Subpart P". This document was issued to. better insure the' safety of workmen entering trenches or excavations. It is mandated by this federal regulation that all excavations., whether they be utility trenches, basement excavations or footing excavations, be installed in accordance with the OSHA guidelines. It is our understanding that these regulations are being strictly enforced and if they are not closely followed, the owner and the contractor could be liable for substantial penalties. The contractor is solely responsible for. designing and' constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. 4.0 REPORT LIMITATIONS This consulting report has been prepared for the exclusive use of the current project owners and other members of the design team for the Proposed 3-Level Residence located at '4924 Watersong Way (Lot 59 Watersong), St. Lucie County, Florida. This report has been prepared 6FA Proposed 3-Level Residence Geotechnical Report Lot 50 Watersong, St. Lucie County, FL May 11, 2017 GFA Project No. 17-1203.00 Page 13 of 13 in accordance with generally accepted local geotechnical engineering practices; no other warranty is expressed or implied. The evaluation submitted in this report, is based in part upon the data collected during a field exploration, however, the nature and extent of variations throughout the subsurface profile may not. become evident until the time of construction. If variations then appear evident, it may be necessary to reevaluate information and professional opinions as provided in this report. In the event changes are made in the nature, design, .or locations of the proposed structure, the evaluation and opinions contained in this report shall not be considered valid, unless the changes are reviewed and conclusions modified or verified in writing by GFA International. Scour elevations used in pile calculations are those provided by the Florida DEP for coastal construction, but may not be adequate for actual scour elevations in hurricane(s) event(s) that exceed the DEP assumptions and cause lower scour elevations. Therefore, GFA analysis is limited to that provided by the DEP scour elevation, and scour analysis is not included in our scope of work. GFA should be provided the opportunity to review the final foundation specifications and review foundation design drawings, in order to determine whether GFA's recommendations have been properly interpreted, communicated and implemented. If GFA is not afforded the opportunity to participate in construction related aspects of foundation installation as recommended in this report or any report addendum, GFA will accept no responsibility for the interpretation of our recommendations made in this report or on a report addendum for foundation performance. 5.0 BASIS FOR RECOMMENDATIONS The analysis and recommendations submitted in this report are based on the data obtained from the tests performed at the locations indicated on the attached figure in Appendix B. This report does not reflect any variations, which may occur between borings. While the borings are representative of the subsurface conditions at their respective locations and for their vertical reaches, local variations characteristic of the subsurface soils of the region are anticipated and may be encountered. The delineation between soil types.shown on the soil logs is approximate and the description represents our interpretation of the subsurface conditions at the designated boring locations on the particular date drilled. Any third party reliance of our geotechnical report or .parts thereof is strictly prohibited without the expressed written consent of GFA International. The applicable SPT methodology (ASTM D-1586), CPT methodology (ASTM D-3441), and Auger Boring methodology (ASTM D-1452) used in performing our borings and sounding, and for determining penetration and cone resistance is specific to the sampling tools utilized and does not reflect the ease or difficulty to advance other tools or materials. C,F� Appendix A - Vicinity Map GFi� v`,cht0.l ' C('ntFC jO �7{i W � f '' SQ lS �FSia7G ' � e Vicinity Map Proposed Three -Level Residence 4876 Watersong Way (Lot 50 Watersong) St. Lucie County, FL GFA Project No..17-1203.00 Site Location 4�� .�-.� xw '}•:.�. fix. G: T 01 } J} �r- Note: Aerial Photograph from GoogleEarth Website Appendix B - Test Location Plan GFi� Legend Test Location Plan Proposed Three -Level Residence 4876 Watersong Way (Lot 50 Watersong) St. Lucie County, FL GFA Project No. 17-1203.00 Approximate Standard Penetration Test (SPT) Boring Locations Appendix C - Notes Related to Borings GFi� NOTES RELATED TO RECORDS OF TEST BORING AND GENERALIZED SUBSURFACE PROFILE 1. Groundwater level was encountered and recorded (if shown) following the completion of the soil test boring on the date indicated. Fluctuations in groundwater levels are common; consult report text for a discussion. 2. The boring location was identified in the field by offsetting from existing reference marks and using a cloth tape and survey wheel. 3. The borehole was backfilled to site grade following boring completion, and patched with asphalt cold patch mix when pavement was encountered. 4. The Record of Test Boring represents our interpretation of field conditions based on engineering examination of the soil samples. 5. The Record of Test Boring is subject to the limitations, conclusions and recommendations presented in the Report text. 6. "Field Test Data" shown on the Record of Test Boring indicated as 11/6 refers to the Standard Penetration Test (SPT) and means 11 hammer blows drove the sampler 6 inches. SPT uses a 140-pound hammer falling 30 inches. 7. The N-value from the SPT is the sum of the hammer blows required to drive the sampler the second and third 6- inch increments. 8. The soil/rock strata interfaces shown on the Records of Test Boring are approximate and may vary from those shown. The soil/rock conditions shown on the Records of Test Boring refer to conditions at the specific location tested; soil/rock conditions may vary between test locations. 9. Relative density for sands/gravels and consistency for silts/clays are described as follows: SPT CPT SANDS/GRAVELS SPT CPT SILTS/CLAYS BLOWS/FOOT KG/QM2 RELATIVE DENSITY BLOWS/FOOT KG/CM1 CONSISTENCY 0-4 0-16 Very loose 0-1 0-3 Very soft 5-10 17-40 Loose 2-4 4-6 Soft 11-30 41-120 Medium Dense 5-8 7-12 Finn 31-50 121-200 Dense 9-15 13-25 Stiff 50+ over 200 Very Dense 16-30 25-50 Very stiff >30 >50 Hard 10. Grain size descriptions areas follows: NAME SIZE LIMITS Boulder 12 Inches or more Cobbles 3 to 12 Inches Coarse Gravel 3/a to 3 Inches Fine Gravel No. 4 sieve to '/a inch Coarse Sand No. 10 to No. 4 sieve Medium Sand No. 40 to No. 10 sieve Fine Sand No. 200 to No. 40 sieve Fines Smaller than No. 200 sieve 11. Definitions related to adjectives used in soil/rock descriptions: PROPORTION ADJECTIVE APPROXIMATE ROOT DIAMETER ADJECTIVE <5% Trace Less than 1/32" Fine roots 5%to 12% Little 1/32" to Small roots 12% to 30% Some ''/a" to 1" Medium roots 30% to 50% And Greater than 1" Large roots Organic Soils: Soils containing vegetable tissue in various stages of decomposition that has a fibrous to amorphous texture, usually a dark brown to black color, and an organic odor. Organic Content <25%: Slightly to Highly Organic; 25% to 75%: Muck; >75%: Peat Gf� Appendix D - Record of Test Borings Gfi� GFA INTERNATIONAL 521 N.W. ENTERPRISE DRIVE, PORT ST. LuC1E, F1,ORIDA 34986 PHONE: (772) 924-3575 - Fax: (772) 924-3580 STANDARD PENETRATION TEST BORING (ASTM D-1586) Client: Coastal Construction and Design Project No.:17-1203.00 Lab No.: Project: Proposed Three -Level Residence Page: 1 of 1 4876 Watersong Way (Lot 50), St. Lucie County, FL Date: 5/4/2017 Elevation: Existing Grade Drill Rig: Simco-24 Water Level: 5.6 feet after 0 hours Drilling Fluid commenced at depth of 10 feet Field Party: RL/CC TEST LOCATION: SPT -1 N27.390350 W80.260350 Laboratory Tests Depth Blows/ N Sample Layer: USCS Description Passing Moisture Organic (feet) 6 in. Value No. From/to No. 200 Content Content 0 ........................... 5 0-8 SP Light gray to gray fine sand, occasional trace shell 1 .....9 13 22 1 --- 2 16 ................. ... 10 3 .....15................. 17 32 2 22 Drilled with power auger from 4 to 6 feet g........ ........ 3 6 ........................... --- 6 7 5 ........................ 4 9 4 8 6 8 - 8'/ PT 'Dark brown organic silt, some sand (muck) 4 8 8%2 -10 SP Gray fine sand 9 7................. 7 1.....5 ... 5 10 ...8... ....... 11 ........ ....... 12 ........ ....... 13 ........ ....... 2 13'/2 - 15 SP Gray fine to medium sand, trace cemented 14 ..... .................. 25 sand fragments 15 16 ........................... 17 ........ ....... 18 ........ ....... 18%2 - 20 SP Gray fine to medium sand, trace cemented 19 ....32 sand fragments 41 78 7 GFA INTERNATIONAL 521 N.W. ENTERPRISE DRIVE, PORT ST. Luc E, FLORIDA 34986 PHONE: (772) 924-3575 - FAx: (772) 924-3580 STANDARD PENETRATION TEST BORING (ASTM D-1586) I Client: Coastal Construction and Design Project: Proposed Three -Level Residence 4876 Watersong Way (Lot 50), St. Lucie County, FL Elevation: Existing Grade Water Level: 5.6 feet after 0 hours Drilling Fluid commenced at depth of 10 feet Project No.:17-1203.00 Lab No.: Page: 2 of 2 Date: 5/4/2017 Drill Rig: Simco-24 Field Party: RL/CC TEST LOCATION: SPT - 1 N27.390350 W80.260350 Laboratory Tests Depth Blows/ N Sample Layer: USCS Description passing Moisture Organic (feet) 6 in. Value No. From/to No. 200 Content Content 20 ------- ------ 21 ........ ....... 22 ........ ....... 23 ........ ....... 21 23%2 - 25 SP Gray fine to medium sand, trace cemented 24 .................. 25 sand fragments ---- 25 ...22 .47.... 8 26 ........ ....... 27 ........ ....... 28 ........ ....... ---- 30 28'/2 - 30 SP Gray fine to medium sand, trace cemented 29 . 32 sand fragments 9 30 ....20 .52... 31 ........ ........ 32 ........ ........ 33 ........ ........ 24 33%2 - 35 SP Gray fine to medium sand, trace cemented 34 23 sand fragments 35 ....23 .46 10 Boring terminated at 35 feet 36 ........ ........ 37 ........ ........ 38 ........ ....... 39 ........ ....... GFA INTERNATIONAL 521 N.W. ENTERPRISE DRIVE, PORT ST. LuCiE, FLORIDA 34986 PHONE: (772) 924-3575 - FAx: (772) 924-3580 STANDARD PENETRATION TEST BORING (ASTM D-1586) Client: Coastal Construction and Design Project No.:17-1203.00 Lab No.. Project: Proposed Three -Level Residence 4876 Watersong Way (Lot 50), St. Lucie County, FL Elevation: Existing Grade Water Level: 5.1 feet after 0 hours Drilling Fluid commenced at depth of 10 feet Page: 1 of 1 Date: 5/5/2017 Drill Rig: Simco-24 Field Party: RL/CC TEST LOCATION: SPT - •2 N27.39031 ° W80.260060 Laboratory Tests Depth Blows/ N Sample Layer: USCS Description Passing Moisture Organic (feet) 6 in. Value No. From/to No. 200 Content Content 0 ........................... 3 0-2 SP-SM Dark brown fine sand, little silt --- 6 1 -- ........................ 9 15 1 2 .....11.................. 2 - 2%2 SP Light gray fine sand 11 ---- 20 2'Y2 - 3 SP,GP Asphalt fragments with sand 3 22 42 2 .3-8 SP Light gray fine sand, some coarse sand 21 sized shell 4 ---- Drilled with power auger from 4 to 6 feet 5 .............. . 3 6 ................ ....... ... 5 ....7..... 6 E 4 g..... 5................... 8-9 PT Dark brown organic silt (muck) - 2 -- 2 , 9 ---- ........................... 4 6 5 9 - 10 SP Light Y a trace shell g fine sand, 10 ..5... ........ 11 ........ ....... 12 ........ ........ 13 ........ ........ 1 13%2 - 15 SM,ML Gray sand and silt 14 2 ---- 15 ...1... ...3.. 6 16 ........ ....... 17 ........ ....... 18 ........ ........ 5 18%2 - 20 SP Gray fine to medium sand, trace cemented 5 sand fragments 6 11 7 GFA INTERNATIONAL 521 N.W. ENTERPRISE DRIVE, PORT ST. LuciE, FLORIDA 34986 PHONE: (772) 924-3575 - FAx: (772) 924-3580 STANDARD PENETRATION TEST BORING (ASTM D-1586) Client: Coastal Construction and Design Project No.:17-1203.00 Lab No.: Project: Proposed Three -Level Residence 4876 Watersong Way (Lot 50), St. Lucie County, FL Elevation: Existing Grade Water Level: 5.1 feet after 0 hours Drilling Fluid commenced at depth of 10 feet Page: 2 of 2 Date: 5/5/2017 Drill Rig: Simco-24 Field Party: RL/CC TEST LOCATION: SPT - 2 N27.39031 ° W80.260060 Laboratory Tests Depth Blows/ N Sample Layer: USCS Description Passing Moisture Organic (feet) 6 in. Value No. From/to No. 200 Content Content 20 ------ ------ 21 ........ ........ 22 ........ ....... 23 ........ ....... 31 23'/z - 25 SP Gray fine to medium sand, trace cemented 24 43 sand fragments 25 ....4? ...8.5.... 8 26 ........ ....... 27 ........ ....... 28 ........ ....... ---- 50/5:: 28 %z - 30 SP Gray fine to medium sand, trace cemented 29 sand fragments 50/5 �� 9 30 .............. 31 ........ ....... 32 ........ ....... 33 ........ ....... 33%z - 35 SP Gray fine to medium sand, trace cemented 34 ...34 ........... 30 ..... sand fragments 35 32 62 10 Boring terminated at 35 feet 36 ........ ........ 37 ........ ........ 38 ........ ........ 39 ........ ........ Appendix E - Discussion of Soil Groups GFi� DISCUSSION OF SOIL GROUPS COARSE GRAINED SOILS GW and SW GROUPS. These groups comprise well -graded gravelly and sandy soils having little or no plastic fines (less than percent passing the No. 200 sieve). The presence of the fines must not noticeably change the strength characteristics of the coarse -grained friction and must not interface with it's free -draining characteristics. GP and SP GROUPS. Poorly graded gravels and sands containing little of no plastic fines (less than 5 percent passing the No. 200 sieve) are classed in GP and SP groups. The materials may be called uniform gravels, uniform sands or non -uniform mixtures of very coarse materials and very fine sand, with intermediate sizes lacking (sometimes called skip -graded, gap graded or step - graded). This last group often results from borrow pit excavation in which gravel and sand layers are mixed. GM and SM GROUPS. In general, the GM and SM groups comprise gravels or sands with fines (more than 12 percent the No. 200. sieve) having low or no plasticity. The plasticity index and liquid limit of soils in the group should plot below the "A" line on the plasticity chart. -The gradation of the material is not considered significant and both well and poorly graded materials are included. GC and SC GROUPS. In general, the GC and SC groups comprise gravelly or sandy soils with fines (more than 12 percent passing the No, 200 sieve) which. have a fairly high plasticity. The liquid limit and plasticity index should plat above the "A" line on the plasticity chart. FINE GRAINED SOILS ML and MH GROUPS. In these groups, . the symbol M has been used to designate predominantly silty material. The symbols L and H represent low and high liquid limits, respectively, and an arbitrary dividing line between the two set at a liquid limit of 50. The soils in the ML and MH groups are sandy silts, clayey silts or inorganic silts with relatively low plasticity. Also included are loose type soils and rock flours. CL and CH GROUPS. In these groups the symbol C stands for clay, with L and H denoting low or high liquid limits, with the dividing line again set at a liquid of 50. The soils are primarily organic clays. Low plasticity clays are classified as CL and are usually lean clays, sandy clays or silty clays. The medium and high plasticity clays are classified as CH. These include the fat clays, gumbo clays and some volcanic clays. GF� OL and OH GROUPS. The soil in the OL and OH groups are characterized by the presence of organic odor or color, hence the symbol O. Organic .silts and clays are classified in these groups. The materials have a plasticity range that corresponds with the ML and MH groups. HIGHLY ORGANIC SOILS The highly organic soils are usually very soft and compressible and have undesirable construction characteristics. Particles of leaves, grasses, branches, or other fibrous vegetable matter are common components of these soils. They are not subdivided and are classified into one group with the symbol PT. Peat humus and swamp soils with a highly organic texture are typical soils of the group. GF�