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HomeMy WebLinkAboutAPPROVED C Soil reprot 5.3.2021 DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 ar A L L TERRA E N G I N E E R I N G & T E 8 T I N G 3866 PROSPECT AVENUE • SUITE 9 • WEST PALM BEACH, FLORIDA 33404 • (561) 881-1939 Phoenix Custom Homes 1760 Jog Road, Suite 120 West Palm Beach, FL 33411 Subject: Report of Geotechnical Services — 3-Level Custom Home 4805 Watersong Way, Fort Pierce, Florida Allterra Engineering &Testing respectfully submits this report of geotechnical services for the subject project. Allterra's services have been performed to meet certain requirements of chapter 18 of the 2020 Florida Building Code, its subsequent revisions, and local amendments. This report is Allterra's instrument-of-service provided for sole reliance and use by Phoenix Custom Homes. Third parties may read this report for information purposes. Project and Scope Reference Documents. Digital copies of the following documents were provided for Allterra's reference in performing its services: • Preliminary drawings 1, 2, 3, 5, and 6 dated 11-16-20 by M.A. Corson &Associates • Boundary & Topo Survey dated 10-2-2019 by Culpepper & Terpening (their file number 19- 239 Lot 3) Project Information. The project is a 3-level custom home proposed for construction upon the subject property. The property is bounded on the west by Watersong Way, on the east by the Atlantic Ocean, and on the north and south by other residential properties. Allterra understands the project is seaward of the Coastal Construction Control Line. For this reason, it is to be designed for supported upon a foundation of grade beams and piles. Scope and Constraints. Allterra was tasked with performing soil-test borings to characterize subsurface conditions and providing recommendations for foundation design (pile length, diameter, and capacity). Specific information on design storm parameters has not been provided at this time. These parameters are provided by the project coastal engineer and typically include information such as breaking wave-crest elevations, eroded-grad elevation, wave impact force and elevation of force resultant, debris impact force and elevation of force resultant, etc. For purposes of this report, Allterra assumed: head-of-pile at 9 feet above existing surface grade and fixed against rotation, and eroded grade at 6 feet below existing surface grade. If these assumptions are erroneous, the conclusions and recommendations of this report may warrant change. Field Work Allterra mobilized personnel and equipment to the project site on 13 January 2021 to perform two soil-test borings. These were advanced from surface grade at opposing corners of the project footprint as field marked by the Client. Penetration testing was performed in the soil-test borings by driving a 2-inch diameter steel sampler with blows of a 140-pound hammer free-falling 30 inches. Copies of the boring logs are attached to this report for the reader's reference. Geotechnical Services—3-Level Custom Home 1 4805 Watersong Way, Fort Pierce, FL 15 January 2021 21-117 DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 Findings Subsurface Profile. Allterra's borings encountered variable subsurface conditions at each boring location. The conceptual subsurface profile can be described as: • Topsoil sampled as dark-gray, fine sand with occasional roots from surface grade to approximately 6 inches below grade, underlain by • Stratum 1 - firm, brown and gray, fine sand to approximately 3 to 4 feet below grade, underlain by • Stratum 2 — firm to very-firm, gray, fine sand with trace of shell to approximately 7 to 7'/2 feet below grade, underlain by • Stratum 3 — soft to firm, dark-brown peat and dark-gray muck to approximately 8 to 9 feet below grade, underlain by • Stratum 4a — firm to loose, gray, fine sand to silty sand-and-shell to approximately 13 to 14 feet below grade, underlain by • Stratum 4b—very-firm to dense, gray, sand-and-shell with occasional lenses of loose sand and organic silt to approximately 27 to 32 feet below grade, underlain by • Stratum 4c — very-firm, gray, sand-and-rock-and-shell to 37 feet below surface grade, underlain by • Refusal (presumed sandstone, limestone, or cemented coquina) Exceptions to the conceptual profile include: • Stratum 4a was sampled as dense, brown, sand-and-rock in B-2. • Refusal was encountered 27 feet below grade in B-1. Groundwater. Groundwater depth is estimated approximately 4 feet below surface grade. Actual depth to groundwater may vary at other times due to changes in hydrologic conditions. Conclusions Pile Capacity. Considering the conceptual subsurface profile and assumption of eroded grade, Allterra estimated the following capacities for 14-inch and 16-inch-diameter auger-cast piles installed to approximately 30 feet below surface grade (approximately 24 feet below eroded grade). Pile Diameter CAXIAL CVERTICAL CHORIZONTAL Uplift Resistance 14 inches 190 Kips 62 Kips 5 Kips 110 Kips 16 inches 220 Kips 72 Kips 8 Kips 126 Kips Notes: CAxIAL= ultimate compressive load capacity. CVERTICAL = allowable compressive load capacity. CHORIZONTAL = allowable horizontal at-fixed-head shear-load capacity ('/2-inch displacement at eroded grade)). Uplift Resistance = (weight of pile + skin friction)/1.5. Kips = 1000 pounds. Pile Evaluation. The pile modeling was based on a conceptual subsurface profile and certain assumptions about the design storm event. The client shall engage a Florida-licensed professional engineer experienced in coastal engineering to review the information and assumptions presented in this report against his expert evaluation. Without the coastal engineer's agreement, additional evaluation may be required. Geotechnical Services—3-Level Custom Home 2 4805 Watersong Way, Fort Pierce, FL 15 January 2021 21-117 DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 Recommendations — Building-Pad Preparation The building pad is defined as the footprint of construction plus 5 feet in all accessible directions. Allterra recommends: 1. Strip topsoil and vegetation (including roots) from building pad and properly waste. 2. Thoroughly wet the exposed surface and allow it to drain to optimum moisture. 3. Mechanically compact exposed surface to at-least 95 percent of maximum-dry-density as determined by the Modified-Proctor compaction test (ASTM D-1557 /AASHTO T-180). 4. Engage Allterra to perform probe-rod and field-density tests to verify compaction standards are achieved. 5. Place fill, where needed, to achieve construction-ready grades in thin lifts and compact (at or near optimum moisture) to at-least 95 percent of maximum-dry-density as determined by the Modified-Proctor compaction test (ASTM D-1557 / AASHTO T-180). Lift thickness will depend upon methods and equipment employed to achieve the target densities. 6. Engage Allterra to perform probe-rod and field-density tests on each 2-foot rise in fill height to verify compaction standards are achieved. 7. Once the building pad is prepared, the contractor shall maintain its condition to prevent erosion or other degradation through the placement of subsequent work. Recommendation —Auger-Cast Piles Pile Materials. Piles shall be formed with minimum 4000 PSI grout placed under pressure as the auger is progressively withdrawn from the borehole. Piles shall be reinforced with five full-depth number-5 steel bars and number-3 ties spaced not more than 16 inches on-center. The structural engineer shall determine the number and distribution of piles considering structural loads and geometry. Piles shall be drilled 8 feet into rock or refusal (less than 1 foot/minute advance). Pile Layout. The number and distribution of piles shall be determined by the structural engineer considering project loads and geometry. Piles shall be spaced at-least 3 diameters center-to-center to avoid group effect on stress distribution in the bearing stratum. Pile-Installation Monitoring. Engage Allterra to monitor installation of piles. For auger-cast piles, monitoring shall include: 1. Check pile layout for conformance to design foundation plan. 2. Observe field trial and calculate gout-pump factor. 3. Observe drilling of pile to verify target depths are achieved. 4. Observe grouting of pile bore to verify acceptable grout return. 5. Sample grout for compressive-strength testing. 6. Observe installation of reinforcing steel to verify full-depth penetration. 7. Test grout specimens to verify design compressive strength is achieved. 8. Calculate grout factors and summarize installation data for each pile. 9. Prepare report of work acceptance signed and sealed by Professional Engineer. Geotechnical Services—3-Level Custom Home 3 4805 Watersong Way, Fort Pierce, FL 15 January 2021 21-117 DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 Qualification Allterra has based its conclusions and recommendations upon certain client-provided information and interpretation of data obtained at discrete points within the limits of exploration. It is possible that conditions may vary between boring locations or beyond the limits of the boring array. Project designs may also change. If additional information about the project or site is discovered that does not appear to conform to the conditions presented in this report, Allterra reserves the right to review the new information and modify its conclusions and/or recommendations where warranted. Closing Thank you for engaging Allterra as your geotechnical consultant. Please call the undersigned if you have questions about this report or need other services. Yours truly, %1i I I I Allterra Engineering 8t�'il- g Certificate of Authorizj'N �9 Ito �. ^ , This item has been digitally signed and E�:, cuSigned by: �,%GEN8 v' I ��.'" . F sealed by Wendell K. Rodgers, P.E. on the ` _ No. 559Bo odate adjacent to the seal. 2363DAF44F... Wendell Rodgeri,*Pr * * = Printed copies of this document are not Principal Engine( '. �� considered signed and sealed and the FL Lic. No. 55964 O STATE of signature must be verified on electronic %,�'��ts '•!�[oarop.'"CO copies. Attachments S110 At. E% ��` Geotechnical Services—3-Level Custom Home 4 4805 Watersong Way, Fort Pierce, FL 15 January 2021 21-117 DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 A L L T E R R A 3866 PROSPECT AVENUE . SUITE 9 • WEST PALM BEACH , FLORIDA 33404 . ( 561 ) 881 - 1939 PROJECT Watersong PUD-PLAT NO. 1 -LOT#3-4805 WATERSONG WAY-Caruso Residence-St. Lucie County, FI LOCATION Northwest Corner of Building Area(Approximate) BORING NO. 1 PROPOSED THREE-LEVEL CUSTOM RESIDENCE DEPTH DESCRIPTION OF MATERIAL Sample Blows No Per Foot DEPTH 1 0"-6" Dark Grey Fine Sand, trace of roots (topsoil) 3-5 1 2 9-6 2 3 6"-3' Brown Fine Sand 5-7 3 4 7-6 4 5 6-7 1 5 6 3'-7' Grey Fine Sand, trace of shell (fragmented) 5_3 6 8 7'-8' Peat 2-1 8 9 2-5 9 10 8'-10' Grey Fine Sand 5-5 10 11 2-3 11 12 3-2 12 13 6-7 13 14 12'-14' Grey Silty Sand, some shell (fragmented) 8-9 14 15 14'-15' Grey Fine Sand, and shell (fragmented) 16-18 15 17 17 18 18 19 10-12 19 20 18'-20' Grey Fine Sand, and shell (fragmented) 14-11 20 21 21 22 22 23 23 24 4-3 24 26 23'-25' Brown and Grey Fine Sand, trace of organics and silt 3 4 26 27 50+ 27 28 27'- Refusal (rock) 28 29 29 30 30 31 31 32 32 33 33 34 34 35 35 36 36 37 37 38 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 CLIENT Phoenix Custom Homes JOB NO. 21-117 DRILLER TM/TRM WATER TABLE N/A DATE 1/13/21 TEST DATA In general accordance with ASTM D-1586 These Soil Boring Tests are Representative of and Apply to the Exact Location and Depth of the Boring. AUTHORIZATION FOR PUBLICATION OF STATEMENTS,CONCLUSIONS OR EXTRACTS FROM OR REGARDING OUR REPORTS IS RESERVED PENDING OUR WRITTEN APPROVAL. DocuSign Envelope ID:53AA2B20-08EE-4AEC-8DOC-CA708F693982 A L L T E R R A 3866 PROSPECT AVENUE . SUITE 9 • WEST PALM BEACH , FLORIDA 33404 . ( 561 ) 881 - 1939 PROJECT Watersong PUD-PLAT NO. 1 -LOT#3-4805 WATERSONG WAY-Caruso Residence-St. Lucie County, FI LOCATION Southeast Corner of Building Area (Approximate) BORING NO. 2 PROPOSED THREE-LEVEL CUSTOM RESIDENCE DEPTH DESCRIPTION OF MATERIAL Sample Blows No Per Foot DEPTH 1 0"-6" Dark Grey Fine Sand, trace of roots (topsoil) 8-9 1 2 10-10 2 3 12-12 3 5 6"-4' Brown and Grey Fine Sand, trace of marl 16-16 5 6 4'-7.5' Grey Fine Sand 3-4 6 8 5-3 8 9 7.5'-9.5' Muck and Peat 3-3 9 10 4-7 10 11 2-4 11 12 5-15 12 13 9.5'-13' Brown Fine Sand, some rock 30-30 13 14 24-15 14 15 13'-15' Grey Fine Sand, and shell (fragmented) 15-15 15 17 17 18 18 19 14-24 19 20 18'-20' Grey Fine Sand, and shell 27-34 20 21 21 22 22 23 23 24 14-22 24 25 26 23'-25' Grey Sand and shell 20 22 26 27 27 28 28 29 20-20 29 30 28'-30' Grey Fine Sand, and shell 24-32 30 31 31 32 32 33 33 34 18-14 34 36 33'-35' Grey Fine Sand, some shell and rock 12-16 36 37 50+ 37 38 37'- Refusal (rock) 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 CLIENT Phoenix Custom Homes JOB NO. 21-117 DRILLER TM/TRM WATER TABLE N/A DATE 1/13/21 TEST DATA In general accordance with ASTM D-1586 These Soil Boring Tests are Representative of and Apply to the Exact Location and Depth of the Boring. AUTHORIZATION FOR PUBLICATION OF STATEMENTS,CONCLUSIONS OR EXTRACTS FROM OR REGARDING OUR REPORTS IS RESERVED PENDING OUR WRITTEN APPROVAL.