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Home My WebLink AboutSW3191205_SHWT Report_2/11/2020/J� SUMMIT ENGINEERING. LABORATORY. TESTING February 10, 2020 Mr. Keith Fenn True Homes 2649 Brekonridge Centre Drive Monroe, North Carolina 28110 Email: kfenn@truehomesusa.com Subject: Estimated Seasonal High Water Table (ESHWT) Determinations Windsong Fairview Road (Highway 218) Indian Trail, North Carolina SUNIlMT Project No. 2022.42 Dear Mr. Fenn: SUNMUT Engineering, Laboratory and Testing, P.C. (SUNMUT) is pleased to submit this letter summarizing our observations of the excavated test pit as related to Estimated Seasonal High Water Table (ESHWT) depth determinations. The test pits were performed at the location of the proposed stormwater BMP ponds to be constructed at the subject site. 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 within the proposed stormwater BMP ponds, assess the engineering characteristics of the subsurface materials, and determination of estimated seasonal high water table depth (if evident). This report contains the following items: • Photographic Logs, Site Vicinity Map and Test Pit Location Plan, • Summary of Test Pit Observations, visual soil classifications and descriptions, • A general review of the subsurface soils and estimated seasonal high water table depth from existing ground surface (if evident), Summary of ESHWT Determination SUMMIT Project Number 2022.42 Windsong, Indian Trail, North Carolina February 10, 2020 • Groundwater level measurements. FIELD STUDY PROCEDURES SUNIlMT visited the site on February 20, 2020 and observed three (3) test pits (identified as TP-1 to TP-3) excavated in the proposed BMP stormwater ponds. The approximate location of the test pits are shown on Figure 2 — "Test Location Plan" provided in Appendix 2. True Homes provided SUNIlMT a plan titled "Master Site Plan" dated August 9, 2017 that indicated the approximate location of the proposed stormwater BMP ponds. The testing locations were located by a member of our geotechnical engineering staff using a recreational -grade hand- held GPS, available aerial photos and existing site features. Test Pit locations were not surveyed and should be considered approximate. The test pits were excavated using a Komatsu 210 LC with a 36" bucket. The test pits were excavated to approximate depths ranging from 8 to 9.5 feet below the existing ground surface. The soils were visually examined and classified in the field. The classification of the soils are described on the "Summary of Test Pit Observation Sheets" provided in Appendix 3. The test pits were backfilled with the excavated materials. GENERALIZED SUBSURFACE STRATIGRAPHY General subsurface conditions observed during our study are described herein. For more detailed soil descriptions and stratifications at a particular test pit location, the respective "Summary of Test Pit Observations Sheet" 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. The general stratigraphy encountered within the test pits are summarized as follows. Surface/Topsoil Beginning from the ground surface, a layer of topsoil (surficial organic soils) was observed at the existing ground surface and the thicknesses were measured to be approximately 2 to 3 inches. Summary of ESHWT Determination SUMMIT Project Number 2022.42 Windsong, Indian Trail, North Carolina February 10, 2020 Residual Soils Residual (undisturbed) soils were encountered below the surface material in all of the test pits. The residual soils extended to beyond the maximum depth of the test pits. The residual soils generally consisted of sandy silts (ML) and elastic silts (MH). Rock and Difficult Excavation Rock and Difficult Excavation were encountered in all of the test pits completed for this exploration. Rock is defined as material that could not be excavated with the equipment used during this exploration. Difficult excavation is defined as soil -like material exhibiting difficult excavation for the track hoe used. Even though rock was not encountered in all of the test pits, the depth of boulders, and rock lenses or seams can vary dramatically in short distances in and between the test locations; therefore, soft/hard weathered rock, boulders or bedrock may be encountered during construction at locations or depths, between the test locations, not encountered during this exploration. GROUNDWATER LEVEL MEASUREMENTS Groundwater, at time the test pits were excavated, was not observed in any of the test pits 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 The ESHWT is defined as 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. CONCLUSIONS Based on our observations, ESHWT indicators in the soil sampled were not encountered in any of the test pits. 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 Summary of ESHWT Determination SUMMIT Project Number 2022.42 Windsong, Indian Trail, North Carolina February 10, 2020 construction are different from those reported, SUNUMT 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. CLOSING SUAINHT 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, SUNIlMT Adam M. Jordan Geotechnical Staff Professional LIST OF APPENDICES ��,,►i, ur►�,�, .�%A CARP ''•. �P,� �,•� _00 0 O F� o ............. SUMMIT•ti't = r .� r Engineering, '• Al. 0 ' Laboratory & LU 23055 � m: Testing, P.G. .' 2/10/20 ' Q,-' •: � �'IpNla 're C-4361 T . .� C • ....... • fl� `w� C q rE 0F��o 1111;4IS 10 Kerry C. Cooper, PE Geotechnical Department Manager 1 Photographic Log 2 Figure No. 1 —Site Vicinity Map Figure No. 2 — Test Location Plans 3 Summary of Test Pit Observation Sheet Summary of ESHWT Determination SUMMIT Project Number 2022.42 Windsong, Indian Trail, North Carolina February 10, 2020 //Ak SUMMIT ENGINEERING * LABORATORY TESTING APPENDIX 1 Figures 4 a 1a QThe Onion Factory a S�ar"r,• �a a ,. c� 0 Fl- w Shirdi Sai Tari 21B Of Charlotte y b Tommy's Taxidermy Q �a Figure 1 Windsong Site Vicinity Map Fairview Road (Highway 218) //1 Union County, North Carolina SUMMIT 3575 Centre Circle Fort Mill, South Carolina 29715 (803) 504-1717 SCALE: NTS SUMMIT Project No.: 2022.42 Summary of ESHWT Determination SUMMIT Project Number 1505.163 Country Lane Property, Charlotte, North Carolina December 28, 2017 //J& SUMMIT ENGINEERING. LABORATORY. TESTING APPENDIX 2 Summary of Test Pit Observations Sheet SUMMARY OF TEST PIT OBSERVATION SHEET WINDSONG INDIAN TRAIL, NORTH CAROLINA SUMMIT PROJECT NO. 2022.42 Test Pit Number Depth (feet)* Soil Description TP-1 0 — 0.25 Approximately 3" of Topsoil 0.25 — 2.5 RESIDUUM: Moist Yellowish Red (5YR, 5/8) Sandy Elastic SILT 2.5 — 4.5 Moist Yellowish Red (5YR, 5/8) and Olive Yellow (2.5Y, 6/6) Sandy Elastic SILT with Manganese Stains 4.5 — 7.5 Moist Yellowish Red (5YR, 5/8) and Olive Yellow (2.5Y, 6/6) Sandy Elastic SILT with Manganese Stains and Rock Fragments 7.5 — 9.5 Strong Brown (7.5YR, 5/8) and Olive Yellow (2.5Y, 6/6) Sandy SILT with Manganese Stains and Rock Fragments No Estimated Seasonal High Water Table Encountered No Groundwater Encountered in Test Pit Hard Digging Encountered at 5 Feet bgs Test Pit Terminated Depth — 9.5 Feet bgs TP-2 0 — 0.25 Approximately 3" of Topsoil 0.25 — 3.5 RESIDUUM: Moist Red (2.5YR, 4/8) Sandy Elastic SILT 3.5 — 4.5 Moist Red (2.5YR, 4/8) and Olive Yellow (2.5Y, 6/6) Sandy SILT with Manganese Stains and Rock Fragments 4.5 — 9 Moist Very Pale Brown (1 OYR, 7/4), Red (2.5YR, 4/8) and Olive (5Y, 5/4) Sandy SILT with Manganese Stains and Rock Fragments No Estimated Seasonal High Water Table Encountered No Groundwater Encountered in Test Pit Hard Digging Encountered at 4 Feet bgs Test Pit Terminated Depth — 9 Feet bgs *Referenced from existing ground elevation Note: Test Pits Performed with a Komatsu 210 LC SUMMARY OF TEST PIT OBSERVATION SHEET WINDSONG INDIAN TRAIL, NORTH CAROLINA SUMMIT PROJECT NO. 2022.42 Test Pit Number Depth (feet)* Soil Description TP-1 0 — 0.16 Approximately 2" of Topsoil 0.16 — 3 RESIDUUM: Moist Red (2.5YR, 4/8) Sandy Elastic SILT 3-5 Moist Olive Yellow (2.5Y, 6/6), Red (2.5YR, 4/8) and Light Olive Brown (2.5Y, 4/6) Sandy SILT with Rock Fragments 5-8 Moist Olive (5Y, 5/4) and Yellowish Red (5YR, 5/8) Sandy SILT with Manganese Stains and Rock Fragments No Estimated Seasonal High Water Table Encountered No Groundwater Encountered in Test Pit Hard Digging Encountered at 3 Feet bgs Test Pit Terminated Depth — 9.5 Feet bgs *Referenced from existing ground elevation Note: Test Pits Performed with a Komatsu 210 LC Summary of ESHWT Determination SUMMIT Project Number 1505.163 Country Lane Property, Charlotte, North Carolina December 28, 2017 SUMMIT ENGINEERING • LABORATORY � TESTfNCa APPENDIX 3 Photographic Logs Photograph Log Windsong SUMMIT Project No. 2022.42 February 10, 2020 A view of Test Pit No. 1 A view of the material excavated from Test Pit No. 1 Photograph Log Windsong SUMMIT Project No. 2022.42 February 10, 2020 A view of Test Pit No. 3 A view of the material excavated from Test Pit No. 3