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Home My WebLink AboutProject Information Florida's Leading Engineering Source • Environmental•Geotechnical-Construction Materials Testing•Threshold and Special Inspections•Plan Review&Code Compliance PV rFRIVA'110N� January 27, 2016 Mr. Dan Regan 387 Nettles Blvd. St. Lucie County, FL RE: Soil Exploration - Proposed 2-Story Residence 387 Nettles Blvd (Lot 387 Nettles Island), St. Lucie County, FL GFA Project# 16-0109.00 GFA International performed soil testing with one Standard Penetration Test (SPT) boring and one auger boring with hand cone penetrometers at the above referenced project. Based on the test results, the soil on which the referenced structure is to rest is capable of sustaining a safe bearing capacity of 2,500 psf. The subsurface exploration activities were performed in accordance with Chapter 18 of the Florida Building Code (latest addition) and applicable ASTM standards. For detailed information on subsurface conditions encountered, please refer to the logs attached to this letter. GFA recommends that the existing slab be demolished, removed and a new foundation system constructed. GFA assumed that a pile foundation is not required due to flood zone or other requirements (to be determined by others). We recommend that the bottom of the footings be founded at a depth of at least 12 inches below finish grade. The depth shall be measured from the lowest adjacent grade. We also recommend a minimum footing width of 18 inches for spread footings and 16 inches for monolithic footings, but not less than 8 inches more than the width of the imposed wall. This report does not state or imply that the foundation soils at the bearing level will remain in the original condition in which they were found during the subsurface exploration activities. Exposure to the environment may weaken the foundation soils at the bearing level if the foundation excavations remain open for a long period of time, or if the foundation soils are exposed to rainfall. Consequently, it is recommended that the excavations for the wall and column footings be performed to final grade and footings constructed as soon as possible to minimize potential damage of the bearing soils. GFA estimates the site is at or near final grade. It is also recommended that the 3 feet below existing grade, the bottom of all new footing excavations and slabs, and all fill material, be compacted to a minimum density of 95% of the Modified Proctor (ASTM D-1557) prior to the placement of the concrete for the footings. To achieve 3 feet of compacted soils per above, the upper 1 or 2 feet may have to be excavated, followed by compaction of the excavation bottom, and then placing and compacting soil to achieve final grade. If compaction cannot be attained due to persistent wetness or the water table near the bottom of the footing excavation, or due to silty/clayey soil 'pumping' during compaction, GFA recommends undercutting below bottom of footing and replacement with No. 57 stone for subgrade that cannot be compacted. The rock fill should be compacted and tamped into the excavation and inspected and verified by a representative from GFA, and tested with hand cone penetrometers, probe rods, or density tests. Foundations and any below grade remains of any structures that are within the footprint of the new construction should be removed so as to not affect structures. Analysis of the foundation performance under hurricane conditions or other storm events, including the effects of loss of soil support due to scour or other forces, is not within the scope of this report, and the recommendations are valid only for normal conditions. Additional analysis and options for foundation systems with scour conditions or other scenarios can be performed if requested. 521 NW Enterprise Drive • Port St. Lucie, Florida 34986 • (772)924.3575 • (772)924.3580(fax) www.teamgfa.com OFFICES THROUGHOUT FLORIDA Proposed 2-Story Story Residence January 27,2016 387 Nettles Blvd. (Lot 387 Nettles Island), St. Lucie County, FL GFA Project#16-0109.00 If there is a nearby seawall or retaining wall, it must have the structural integrity to withstand the loadings imposed by the new structure. Evaluation and design of the nearby seawalls and retaining walls are the responsibility of the structural engineer, specialty engineer, contractor, or others. Evaluation of the seawall is not within our scope of work. CLOSURE This consulting report has been prepared for the exclusive use of the client. This report has been prepared 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. The analysis and recommendations submitted in this report are based on the data obtained from the tests performed. 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. 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 (ASMT D-1452) used in performing our borings/soundings and for determining penetration resistance is specific to the sampling tools utilized and does not reflect the ease or difficulty to advance other tools, equipment or materials. We appreciate the opportunity to be of service to you on this project and look forward to a continued association. Please contact the undersigned if you have any questions or comments, or if we may further assist you as your plans proceed. Sincerely,oO D W. asU 000°1 GFA InV? 1(Pm6,4ryi. lc °°e FBPE4� M F*°°•'A '® eon;�dW. Moler, P:E. f ; CC; i an Collie, E.I. Seni"botechnical:Engineq'r4tr® r j Manager Florio gistration No. 60& Z O R .C-> mow Attachments�000�/�gpdiMAP, Test Location Plan, Standard Penetration Test(SPT) Borings(1),Auger Boring (AB) Logs (1), Notes Related to Test Borings Copies: Client(2) e� W N D{ IF 4y *T��ESTING•Rf'P Vicinity Map 38.7 Nettles Blvd (Lot 387 Nettles Island) St. Lucie County, Florida t Project f tSite LocationNote:Aerial Photograph from GoogleEarth Website P dam' ♦ .�•d;�"` °w, �~ ..ice �'✓� 1� ,T • -� '� ;� f' .ram, �''*_ - �.e+ etties 8i�u y�q;� L':m��T �.!! �� .�Jt�:tl�� .iM,�,nr..f.,,=r;E� is�,�ria• -•r19;rice+ i n .�.: �Ft.»Q. .y ylfRti ATt0�P Test Location Plan 387 Nettles Blvd (Lot 387 Nettles Island) St. Lucie County, FL GFA Project No. 16-0109.00 4 S' ' x AB-1 5 qr or r �y y 1i8 D e asi - d s . Legend Approximate Standard Penetration Test(SPT)Boring&Auger Boring(AB)Location 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) Client: Mr.Dan Regan Project No.:16-0109.00 Lab No.: Project: 387 Nettles Blvd(Lot 387 Nettles Island) Page: 1 of 1 St.Lucie County,Florida Date: 1/21/2016 Elevation: Existing Grade Drill Rig: Simco-24 Water Level:4 feet after 0 hours Drilling Fluid commenced at depth of 10 feet Field Party: PM/WG Hand Auger with Hand Cone Pentrometer Test(HCP in ksf)performed in top 4 feet TEST LOCATION: SPT- 1 N27.28844° W80.22183° 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%Z SP Light brown fine sand 1 HCP= 80+ ___ 1 2 HCP= 80+ ---• 3 HCP= 80+ 4 HCP= 80-P 3%-7 SP Gray fine sand,trace shell fragment: 6 ---- 5 -4 - ------------ 1 5 3 --- 6 - 1 ---- 2 7 ------- ------ 1 3 4 7- 11 SP Brown fine sand,trace shell fragments ---- 8 2 --- 2 ---- 2 9 ------- ------ 2 4 5 ---- 2 10 -3- --- ---- 5 11 ---5 10 6 11 - 16 SP-SM Gray fine sand,little silt 12 •5 ••- 3 4 5 9 7 ----14 -.1 --- 5 ---15 • 5 • •6••• •11•• 8 7 16 .......... g Borin Terminated at 16 feet 17 ---- --- 18 ---- --- I' Florida's Leading Engineering Source y�FRN14T�0�P AUGER BORING LOGS WITH HAND CONE PENETROMETER (HCP) TESTS Client: Mr. Dan Regan Project No: 16-0109.00 Project: 387 Nettles Blvd (Lot 387 Nettles Island) Lab No: St. Lucie County, Florida Test Date: 01/21/2016 Elevation: Existing Grade Technician: PM/WG/CM TEST LOCATION: AB — 1 N27.288520 W80.221780 HCP Depth(feet) Description (color,texture, consistency, remarks) Depth Reading 0- 3'/2 Light brown fine sand, trace shell fragments, trace roots SP 1 50 3'/2- 5'/2 Brown fine sand, little shell fragments SP 2 30 5'/2-7'/2 Gray fine sand, some shell fragments SP 3 50 7Y2 - 10 Gray fine sand, trace shell fragments SP 4 30 5 20 6 40 7 40 8 20 9 20 10 60 Water table at 43/feet below ground surface 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/CM RELATIVE DENSITY BLOWS/FOOT KG/CM- CONSISTENCY 0-4 0-16 Veryloose 0-1 0-3 Verysoft 5-10 17-40 Loose 2-4 4-6 Soft 11-30 41-120 Medium Dense 5-8 7-12 Firm 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 Y44 to 3 Inches Fine Gravel No.4 sieve to%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''/4" Small roots 12%to 30% Some '/4"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