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HomeMy WebLinkAboutSW6210201_Ryans Run_SHWT Report_20210416Scott Cole, NCLSS 312 Copples Road Ext Asheboro, NC 27205 (336) 460-4554 Double D Engineering, PLLC Attn: Mr. Lee Humphrey 150 S. Page Street Southern Pines, NC 28387 April 7, 2021 Re: Seasonal High -Water Table Identification and Soil Infiltration Rates: Ryans Run; Hoke County NC Calloway Road Soil conditions and infiltration rates were evaluated and measured on the above -referenced property within the proposed storm water BMP devices. Work was conducted in accordance with Parts A-2 and C- 1 of the North Carolina Department of Environmental Quality Stormwater Design Manual. Soil samples were evaluated with a hand auger. SEASONAL HIGH WATER TABLE IDENTIFICATION Seasonal High Water Table depth is determined by field evaluation for soil wetness conditions which are indicated by the presence of redoximorphic (redox) features with a chroma of 2 or less (in Munsell color notation) in mottles or the horizon matrix. Colors of chroma 2 or less due to relic minerals from parent material (underlying rock), anaerobic activity created by placement of fill material, or soil textural class transitions (perched water) are not considered as indicators for seasonal high water. Upon determination of SHWT depth, an additional 6" will be deducted from the observed depth to account for capillary fringe water movement above the SHWT. Stormwater infiltration trenches are designed to ensure the lowest point is at least two feet above the Seasonal High Water Table (SHWT). SATURATED HYDRAULIC CONDUCTIVITY (K ,t) Soils evaluated on this property are typical of those within the Blaney Loamy Sand series (BaB, BaD) and the Vaucluse Loamy Sand series (VaB). These soil series consist of deep, well drained soils with varying rates of permeability. Infiltration rates were measured to determine if soil conditions were suitable for the installation of stormwater infiltration trenches. Infiltration rates were measured using a Johnson Constant Head Permeameter. Measurements were recorded at varying intervals until equilibrium was reached. A summary of observations within the proposed Stormwater BMP Device is shown in the table below. BMP Device Site #1 SHWT Munsell Color Ksat I�at &at (inches below Notation (0-30"; SL) (30-48"; SCL) (48-96"; SCL/SC ground surface mixed mineralogy) with capillary fringe ad'ustment 90" (7.5') (SHWT 2.5Y 8/1 18" / hour .8" / hour Not Measured elevation 292.5') 2.5Y 7/1 Scott Cole, NCLSS 312 Copples Road Ext Asheboro, NC 27205 (336) 460-4554 BMP Device Site 42 SHWT Munsell Color Ksa, Ksat &at finches below Notation (0-4`8"; SL) (48-80"; SCL) (80-100'; SCL/SC ground surface mixed mineralogy) with capillary Erin a adins tment 96" (8') (SHWT 2.5Y 8/1 18" / hour .8" / hour Not Measured elevation 300') 2.5Y 7/1 CONCLUSION Field evaluation of hydraulic conductivity provides estimations of soil infiltration rates; however, methods used to measure these rates can influence the results. Side walls of the bore hole are "smeared" by the soil auger as the hole is prepared and loose soil in the bottom of the hole is placed in suspension when water is applied; both factors negatively influence water infiltration rates. To help overcome these issues, after excavation of each infiltration trench, it is recommended the trench bottom and sidewalls be raked and dusted with pulverized limestone. These are practices that have been in place within the on -site wastewater industry to help loosen the soil and aid in restoration of soil structure. I am pleased to be of service in this matter and can be contacted at your convenience should you have any questions concerning information within this report. Thank you, C_ QQ� —2 Scott Cole North Carolina Licensed Soil Scientist Fr�:> ,.v ! 1 1 PAP � • �\ \\ �\\��\fir ' ,� ;,j�'i/y'� _ !'�' ilffll® �.r. ` �III�iI r r r ►. couNTY � I �` 4 8g1702 1 J R20 / / t19� 1n SIGN EASEMENT (rrp•) 30' R. 'tip. \I 10' ?-70' VC 4T-•/ DISYINCE (TYP'.) ' W,W CAMERON 554800001237 900-238 ZONED R20 9XINO. ORAutAGE Ms. ATION AN13 TOME 0 S %1 inch = 200 feet 'J I BMP Site #2 SHWT: 96" (8') bgs SHWT Elevation: 300' Ksat 0-48" SL: 18" / hour Ksat 48-80.' SCL: .8" / hour Ksat 80-100" SCL mixed min: Not Measured j, PERMANENT STORM ORAINA •, ! ooE,CFATEO SMEMENT WLE RMANEN7 ,r0`sii S'scl SHWT J� � ''� �� ', GILCIFJtT 15UffMAN ' ♦ ; 5ea 6D tt 48st 80sc1 8. 1 564990001011 A 300-399 t I 2ONE0 R20 _ HELEN TURNER SPACE 584960=109 Cl) 0ARO4�k^VMS $T ZONEDR20 54ii9E2i1�p30'l7 IOi--! 0: STANLEY zxi6 R;0 NORTHCUTT 5049800ri1O10 MAXIE S 14E-87 M90D 1111 d ZONED R20 421-3y DESSIE OIL8iRr Eh tAAlN ZONED 0 .56a960O0'IJ, 713-797 ZOOEO R20 Eli RY , RUIN o 7"4- 1 HOKE COI Y, N® 1'H CAROLINA