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Home My WebLink AboutSW3141103_Soils/Geotechnical Report_20240416 (2) ECS C A R O L I N A S, L L P "Setting the Standard for Service" I Geotechnical • Construction Materials • Environmental • Facilities N.ljf4jr.t,.1141FfIjtl1. I11jFRn1 torn November 14, 2014 Mr. Derek Salfia The Keith Corporation 5935 Carnegie Blvd. Charlotte, NC 28209 Reference: Report of SHWT Study Project Marley Salisbury, Rowan County, North Carolina ECS Project 08-10438 Dear Mr. Salfia ECS Carolinas, LLP (ECS) is pleased to provide you with our Report of Seasonal High Water Table (SHWT) Study for the Project Marley site in Salisbury, North Carolina. Project Information The approximate 32.55-acre site is located on the south side of Corporate Center Drive, south of Julian Road in Salisbury, Rowan County, North Carolina. The Rowan County parcel number associated with the site is 402-A-001. ECS understands that a warehouse and office building are proposed for the site. An aerial photograph was prepared by ECS identifying three SHWT boring locations (Figure 1), which are in general proximity to proposed stormwater devices. The soil investigation was conducted with a hand auger to a depth of 10 feet or auger refusal below ground surface (bgs). Scope of Services ECS conducted a study/investigation of the soils to identify the depth of the seasonal high water table, if present. The properties and characteristics of the soils retrieved from the borings were observed and recorded in field notes. The properties include texture, depth, the presence of restrictive horizons, depth to seasonal high water table, coarse fragments, etc. The assessment was conducted in accordance with current soil science practices and technology. Seasonal High Water Table Study Below is a summary of the soils retrieved from the borings. SHWT Boring 1 —The surface layer to a depth of 4 inches bgs consists of brown sandy loam. The structure appears to be granular with very friable consistence. The subsurface layer from 4 to 9 inches bgs consists of brown and yellow sandy clay loam. The structure appears to be weak fine angular blocky with firm, sticky, plastic consistence. The subsurface layer from 9 to 48 inches bgs consists of orange and brown clay, with gray mottles identified at 15 inches bgs. The structure appears to be moderate medium angular blocky with very firm, sticky, very plastic consistence. The subsurface layer from 48 to 68 inches bgs consists of brown and gray clay. The structure appears 1812 Center Park Drive, Suite D, Charlotte, NC 28217 • T 704-525-5152 • F. 704-357-0023 • www.ecslimited.com F_S t.pcd letvrrS R I C • Fi S is x I I P• KS Cenral,R I C•FCS Flond3,II C• FGS Md Ariant r t I C. • Fi S Midwest 1 I tic .•FCS Sr.jtt .ic I 1 i s • FC.S Tex.,I I P SHWT Study Project Marley Salisbury, Union County, North Carolina ECS Project 08-10438 November 14, 2014 to be angular blocky with very firm, very sticky, very plastic consistence. Auger refusal was encountered at a depth of 68 inches bgs. SHWT Boring 2 — The surface layer has been removed due to recent tree clearing and grading activities. The ground surface to a depth of 16 inches bgs consists of olive brown clay. The structure appears to be angular blocky with very firm, very sticky, very plastic consistence. The subsurface layer from 16 to 25 inches bgs consists of multicolored saprolite with sandy clay loam texture. The structure appears to be massive/structureless with friable, non-sticky non-plastic consistence. Few clay lenses were identified within this layer. The subsurface layer from 25 to 120 inches bgs consists of multicolored saprolite with a sandy loam texture. The structure appears to be massive/structureless with friable, non-sticky, non-plastic consistence. No clay lenses were identified within this layer. SHWT Boring 3 —The surface layer to a depth of 3 inches bgs consists of brown sandy loam. The structure appears to be granular with very friable consistence. The subsurface layer from 3 to 36 inches bgs consists of gray clay. The structure appears to be moderate, medium, angular blocky with very firm, very sticky, very plastic consistence. The subsurface layer from 36 to 72 inches bgs consists of brown gray clay loam. The structure appears to be moderate medium angular blocky with very firm, sticky, very plastic consistence. A clay increase was noted within the subsurface layer from 72-80 inches bgs, and consisted of brown and gray clay. The structure appears to be angular blocky with very firm, very sticky, very plastic consistence. The subsurface layer from 80 to 86 inches bgs consists of brown gray clay loam. The structure appears to be weak, medium, sub- angular blocky with firm, slightly sticky, slightly plastic consistence. Weathered rock was noted in the aforementioned horizon. Auger refusal was encountered at a depth of 86 inches bgs. Findings SHWT Boring 1 — Evidence of a SHWT appears at a depth of 15 inches bgs. Reducing conditions were noted to the depth of auger refusal. It is possible that the shallow depth of the SHWT is from an episaturated condition, or perched water table, due to slow saturated hydraulic conductivity of the soil horizon occurring within and below 15 inches. Although field results indicate 15 inches bgs as the SHWT, a drill rig will be required to advance to deeper depths to make a more conclusive determination of a perched or actual SHWT depth. SHWT Boring 2 — Evidence of a perched SHWT appears at a depth just bgs. Reducing conditions were noted to the depth of approximately 16 inches, indicating a restrictive soil horizon. Due to the low saturated hydraulic conductivity of this layer, caused by expansive clay mineralogy, an episaturated condition (perched water table)was identified. Soil horizons below the expansive clay, from 16 to 120 inches bgs, did not exhibit indicators of an actual SHWT. SHWT Boring 3 — Evidence of what is perceived as a perched SHWT appears at a depth 3 inches bgs. Reducing conditions were noted to the depth of auger refusal. Soil depth horizons occurring from 3 to 36 inches, and 72 to 80 inches, exhibited restrictive layers caused by expansive clay mineralogy. Very low saturated hydraulic conductivities would occur throughout the soil profile as a result of expansive mineralogy, very poor structure, and depth to rock. A drill rig will be required to advance to deeper depths to make a more conclusive determination of a perched or actual SHWT depth. 2 SHWT Study Project Marley Salisbury, Union County, North Carolina ECS Project 08-10438 November 14, 2014 The type of stormwater management facility designed is based on the depth of the SHWT or confining layer. The information above may be potentially utilized to determine the type of stormwater management facility best suited for this site according to the North Carolina Division of Water Quality Stormwater Best Management Practice Manual, dated July, 2007. Closing ECS is pleased to offer our professional services and look forward to assisting in any of your site analysis needs in the future. If you have any questions or require further assistance, please contact us at 704-525-5152. Respectfully, ECS CAROLINAS, LLP �;,--fit,,.•y,;Le it, -A f J.� (A . 4 W. Brandon Fulton, LS PWS John S. Lair, P.G. Environmental Department Manager Principal Geologist Attachment: Figure 1 —SHWT Boring Location Map Fr ti ..j q P\ I o, I f7 �� Q, 4 4P }� y k 3 0 1 ,. le IIIIIIWO 'SUrhip t.Fa64Y.N - . Nk r • /:41, M• �� 4 ot° •A• ,c9 �e - SHWT Boring 1 i % - r G.. •�`�°'`CAntcx.Ot "� 'A • 4 • \ . ,x SHWT Boring 2 • /fi -- . SHWT Boring 3 . • 4 ., ' , i-_ a � Aill - LEGEND • . i \SGC" 7- 0 = Boring location O # • FIGURE 1 SOURCE: SEASONALLY HIGH WATER TABLE BORING MAP GOOGLE MAPS — - PROJECT MARLEY 2014 `\ 1010 CORPORATE CENTER DRIVE SCALE AS SHOWN SALISBURY, ROWAN COUNTY NORTH CAROLINA ECS PROJECT NO. 08-10438