The URL can be used to link to this page

Home My WebLink AboutSW3210101_1000-2022.62 Summary Letter for ESHWT Determination for Glencroft Phase 2_202103244V,M/0 t. ft 5-ARS CLtIESRATING IS yl�A'RS SUMMIT ENG IN EERING, LABORATORY & TESTI NG � P.0 - October 18, 2019 Mr. Keith E. Fenn, PE True Homes 2649 Brekonridge Centre Drive Monroe, North Carolina 28110 Email: Kfenngtruehomesusa.com Subj ect: Estimated Seasonal High Water Table (ESHWT) Determination Glencroft — Phase 2 Glencroft Drive Union County, North Carolina SUNUMT Project No. 2022.62 Dear Mr. Fenn: SUNUMT Engineering, Laboratory and Testing, P. C. (SUNUMT) is pleased to submit this letter summarizing our observations of the soil test boring as related to Estimated Seasonal High Water Table Elevation (ESHWT) determination. This report contains a brief description of the project information provided to us, general site and subsurface conditions revealed during this study. PURPOSE OF STUDY The primary purpose of this study was to obtain information regarding the subsurface conditions near the proposed detention pond, assess the engineering characteristics of the subsurface materials, and determination of the estimated seasonal high water table mark (if evident). This report contains the following items: ENGINEERING & LABORATORY* TESTING 3575 Centre Circle Drive I Fort Mill, South Carolina 29715 1 (704) 504 - 1717 1 (704) 504 - 1125 (Fax) WWW.SUMMIT-COMPANIES.COM Summary of ESHWT Determination SUMMIT Project No. 2022.62 Glencroft — Phase 2 October 18, 2019 0 Photographic Logs, Site Vicinity Map and Boring Location Plan, 0 Summary of Test Boring Observations, visual soil classifications and descriptions, 0 A general review of the subsurface soils and estimated seasonal high water table depth from existing ground surface (if evident), 0 Groundwater level measurements. EXPLORATION PROCEDURES SUMMIT visited the site on October 8, 2019 to perform a soil test boring (identified as Boring B- 12) in the proposed detention pond. The approximate location of the boring is shown on Figure 2 — "Boring Location Plan" provided in Appendix 2. The client (True Homes) provided SUMMIT a plan that indicated the approximate location of the proposed detention pond. The boring location was surveyed prior to this study and the existing ground elevation was provided to us. We recommend the actual test location be surveyed in determine the existing ground elevation and boring location. The soil test boring was performed using a Diedrich D50 drill rig and extended to an approximate depth of 12.1 feet below the existing ground surface. Hollow -stem, continuous flight auger drilling techniques were used to advance the boring into the ground. Standard Penetration Tests (SPT) were performed within the mechanical boring at designated intervals in general accordance with ASTM D 1586. When properly evaluated, the SPT results can be used as an index for estimating soil strength and density. In conjunction with the penetration testing, representative soil samples were obtained from each test location and returned to our laboratory for visual classification and potential laboratory testing. The soil samples collected were visually examined and classified in general accordance with ASTM D-2488. The Munsell Soil Color Charts (2009 Revision) were used to identify the hue, value, and chroma of soil samples. Water level measurements were attempted at the termination of drilling. The classification symbols are depicted on the "Boring Log" provided in Appendix 3. 2 Summary of ESHWT Determination SUMMIT Project No. 2022.62 Glencroft — Phase 2 October 18, 2019 GENERALIZED SUBSURFACE STRATIGRAPHY General subsurface conditions observed during our geotechnical study are described herein. For more detailed soil descriptions and stratifications at a particular test location, the respective "Boring Log" provided in Appendix 3 should be reviewed. The horizontal stratification lines designating the interface between various strata represent approximate boundaries. Transitions between different strata in the field may be gradual in both the horizontal and vertical directions. Beginning from the ground surface, a layer of topsoil (surficial organic soils) was observed with a thickness of approximately 3 inches. Beneath the topsoil layer, residual (undisturbed) soils were encountered that consisted of lean clays. Partially Weathered Rock (PWR) and auger refusal conditions were encountered at approximate depth of 10 and 12.1 feet, respectively. GROUNDWATER LEVEL MEASUREMENTS At the time of drilling, groundwater was not observed in the boring. After waiting more than 24 hours, water level was observed at an approximate depth of 7 feet below the existing ground surface. Please note that groundwater levels tend to fluctuate with seasonal and climatic variations, as well as with some types of construction operations. ESTIMATED SEASONAL HIGH WATER TABLE ESHWT is defined as the shallowest depth to a wet soil layer as a result of "true" or "permanent" groundwater at any time during the year. The ESHWT is typically identified with a change in the color of the soil layer due to water staining (typically, gray redoximorphic depletions and mottling). Spots or blotches of different color or shades of color interspersed with a dominant color in soil, commonly referred to as mottling. Mottling is a historic indication for the presence of ground water caused by intermittent periods of saturation and drying, and may be indicative of poor aeration and impeded drainage. Mottling is a "general indication of groundwater" flow through this layer, but it is not known whether the groundwater flow was recent. 3 Summary of ESHWT Determination SUMMIT Project No. 2022.62 Glencroft — Phase 2 October 18, 2019 CONCLUSIONS Based on our observations, Estimated Seasonal High Water Table (ESHWT) indicators (water stained soils) indicators were evident in soils sampled in the boring. Please note that the water level observed in the boring could be perched water that most likely developed above low permeability PWR stratum Perched water conditions differ from the "true" or "permanent" water table. A perched water table is water standing above an unsaturated zone and is often influenced by soil conditions, and occurrence of less permeable soils. Where the ESHWT is defined as the shallowest depth to a wet soil layer as a result of "true" or "pennanent" groundwater at any time during the year. The BMP designer should take into consideration that perched water conditions may exist above the low permeable PWR stratum. The following table summarizes the results of the boring and our observations. Summary Table of the Boring Results and Our Observations Auger GW Depth PWR Refusal Boring ESHWT GW Depth After Approx. Approx Test Depth Depth ATD 24 Hours Depth Depth Location (Feet)' (Feet)' (Feet) (Feet) (Feet) B- 12 12.1 6 NE 7 10 12.1 1 Depths from existing ground surface. NE — Not Encountered in Boring. The analyses and recommendations submitted in this report were based, in part, on data obtained from this study. If the above -described project conditions are incorrect or changed after the issuing of this report, or subsurface conditions encountered during construction are different from those reported, SUNFMT should be notified and these recommendations should be re-evaluated based on the changed conditions to make appropriate revisions. We have prepared this report according to generally accepted geotechnical engineering practices. No warranty, express or implied, is made as to the professional advice included in this report. 4 Summary of ESHWT Determination Glencroft — Phase 2 CLOSING SUMNHT Project No. 2022.62 October 18, 2019 SUMNHT appreciates the opportunity to provide our professional services for you on this project. If you have any questions concerning the information in this proposal or if we may be of further service, please contact us at 704.504.1717. Sincerely, SUNUMT Todd A. Costner, E.I. Senior Professional I I I i I I CA .. . ....... 0 SUMM Engineering, z 1 Laboratory & 0 - LLI Testing, P.C. 1 z C-4361 LIST OF APPENDICES I Photographic Log 2 Figure No. I —Site Location Map Figure No. 2 — Test Boring Location Plan 3 Boring Log 5 -�t CAI 23055 1 1`0 Coe "vessel's iattO ;e Kerry C. Cooper, P.E. Geotechnical Department Manager Summary of ESHWT Determination Glencroft — Phase 2 SUMMIT Project No. 2022.62 October 18, 2019 r/ "� r - -7. / -. 71& "'tLEBRATING 15 YEARS UMMIT ENGINEERING, LABORATORY & TESTING, P.C. APPENDIX I Photographic Log Summary of ESHWT Determination SUMMIT Project No. 2022.62 Glencroft — Phase 2 October 18, 2019 Boring B-12 Samples (Approximate Depth = 0 to 10 feet below existing ground surface) Summary of ESHWT Determination Glencroft — Phase 2 4rf"� r 71'/ %�r-LEJBRATMG 15 YEAR5 SUMNHT Project No. 2022.62 October 18, 2019 UMMIT ENGINEERING, LABORATORY & TESTING, P.C. APPENDIX 2 Figures nrty I :)od Ilion Homes �9. � Toll road) F1 751] Styx Cuthbertson Trucking .A I A 9.6 vsl� SITE 6;� Fl-7511 1w F1 7 54] F1 7-5 3� —7 qA 04, 1%, O� F17541 I Figure I Glencroft Site Vicinity Map Phase 2 CE'-EBRATiNG 15 YEPIR5 Ansonville Road Wingate, North Carolina SUMMIT ENGINEERING, �ORATORY & TESTING, P.C. 3575 Centre Circle Fort Mill, South Carolina 29715 �SCALE:NTS SUMMIT Project No.: 2022.62 (803) 504-1717 t rr, r- r -T-Tr -I F-7 r- @ L J L + AJ� J L L — _j zz r- L 3 -- —_J C L Fr. 1 0 0 elf- L 7 All a Fr— mot -1 0 L-L, -J pt vr-5i- L Hr&Z _01 PN > r ��FM'41 - > v _J L J 0 PWR 101,:;:' �� 0 "k ME !rA I % @ ;T�IWT 61 r @ &A. r 0 : 1 1 ) Sz A 3a. L J _J + zz zz -J ZE ri zz X�rrr, 0 0 0 0 Y- F_ IF 6 tie ril JE sill 4k 5.1il 1 Figure 2 Glencroft I I! *_ 1-/ lort Phase 2 'LEBRATING IS YEARS Boring Location Plan Ansonville Road IIANNEMOL Approx. Test Pit Location SUMMIT Wingate, North Carolina ENGINERFUNG, L�O�TO�& TESTMG, P.C. 3575 Centre Circle Fort Mill, South Carolina 29715 (803) 504_ 1717 SCALE:NTS SUMMIT Project No.: 2022.62 Summary of ESHWT Determination Glencroft — Phase 2 SUMNHT Project No. 2022.62 October 18, 2019 t7r-. / -. 74-11L L-EBRATING 15 YEAR5 UMMIT ENGINEERING, LABORATORY & TESTING, P.C. APPENDIX 3 Boring Log 9 SUMMIT Engineering, Laboratory & Testing, P.C. KEY TO SYMBOLS 3575 Centre Circle Fort Mill, South Carolina 29715 SUMMIT 704.504.1717 � ........ ...... summit-companies.com CLIENT True Homes PROJECT NAME Glencroft Phase 2 PROJECT NUMBER 2022.62 PROJECT LOCATION Wingate, Union County, North Carolina LITHOLOGIC SYMBOLS SAMPLER SYMBOLS (Unified Soil Classification System) Standard Penetration Test F-1 BLANK CH: USCS High Plasticity Clay CL: USCS Low Plasticity Clay FILL: Fill (made ground) IVILS: USCS Sandy Silt TOPSOIL: Topsoil PWR: Partially Weathered Rock WELL CONSTRUCTION SYMBOLS ABBREVIATIONS LL -LIQUID LIMIT (%) TV -TORVANE PI -PLASTIC INDEX(%) PID -PHOTOIONIZATION DETECTOR W - MOISTURE CONTENT (%) LIC -UNCONFINED COMPRESSION DID - DRY DENSITY (PCF) ppm -PARTS PER MILLION NP -NON PLASTIC Water Level at Time -200 - PERCENT PASSING NO. 200 SIEVE Drilling, or as Shown PP - POCKET PENETROMETER (TSF) Water Level at End of Drilling, or as Shown Water Level After 24 Hours, or as Shown SUMMIT Engineering, Laboratory & Testing, P.C. BORING NUMBER B-12 3575 Centre Circle 11AM1k Fort Mill, South Carolina 29715 PAGE I OF I SUMMIT 704.504.1717 summit-companies.com CLIENT True Homes PROJECT NAME Glencroft Phase 2 PROJECT NUMBER 2022.62 PROJECT LOCATION Wing te, Union County, North Carolina DATE STARTED 10/8/19 COMPLETED GROUND ELEVATION HOLE SIZE 6 inches DRILLING CONTRACTOR FST GROUND WATERICAVE-IN: DRILLING METHOD Hollow Stem Auger AT TIME OF DRILLING --- GW NE ATID LOGGED BY FST CHECKED BY A. Jordan TATENDOFDRILLING 7.00ftGW> 24HrsAt7feetbqs NOTES Refer to Figure 2 "Boring Location Plan" for Approx. Boring Location AFTER DRILLING --- Lu A SPT N VALUE A z 0 U) 0 20 40 60 80 100 = Q-0 MATERIAL DESCRIPTION Lu LU ED LU > 3: �- 0 z -j D < PL MC LL 1 -11 W < LL -j 0- 0 j Fn 0 > 0 20 40 60 80 100 El FINES CONTENT (%) El -j Lu (D �z < 0 Lu 0 z U) 0 2 0 4 0 6 0 8 0 100 Approx. 3" of Topsoil (CL) RESIDUUM: SPT 6-10-12-10 Very Stiff Pale Brown (2.5Y, 7/4), Light Gray (5Y, 7/2) and 1 (22) Brownish Yellow (1 OYR, 6/6) Sandy Lean CLAY — — — — — — — — — — — — — — — — — — — — — — — — — — (CL) Hard Pale Brown (2.5Y, 7/4), Light Gray (5Y, 7/2) and — — — - ........ Brownish Yellow (1 OYR, 6/6) Sandy Lean CLAY SPT 34-17-20-20 2 ........... (37) — — — — — — — — — — — — — — — — — — — — — — — — — — — — — - (CL) Very Stiff Pale Brown (2.5Y, 7/4), Light Gray (5Y, 7/2) and . . . . . . . . . . . . . . . . .... ............ ....... 5.0 Yellowish Red (5YR, 5/6) Sandy Lean CLAY SPT 3 6-10-16-18 (26) — — — — — — — — — — — — — — — — — — — — — — — — — — (CL) Hard Pale Brown (2.5Y, 7/4), Light Gray (5Y, 7/2) and — — — - . ........ ... ...................... ........ Yellowish Red (5YR, 5/6) Sandy Lean CLAY SPT 8-11-20-23 ESHWT - 6 feet bgs 7ft 4 (31) — — — — — — — — — — — — — — — — — — — — — — — — — - (CLFV;ry Hard Pale Brown (2.5Y, 7/4), Light Gray (5Y, 7/2) and ........ Yellowish Red (5YR, 5/6) Sandy Lean CLAY SPT 20-30-33-50/5" 5 (63) 10.0 (ML) Partially Weathered Rock (PWR) when sampled becomes SPT ........... - .... ........ ........ 50 Pale Brown (2.5Y, 7/4) Sandy SILT with Rock Fragments 6 (50/1.75 1 Bottom of Boring at 12.1 feet bgs, Auger Refusal 50 50/0.75" 15.0 20.0