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Groundwater Sampling and Analysis Plan <br /> This information provided in this subsection of Exhibit G is intended to satisfy the requirements <br /> outlined in the Groundwater Monitoring and Protection Technical Bulletin dated November 19, <br /> 2019: <br /> Existing Groundwater Conditions <br /> The near surface groundwater is part of the alluvial aquifer along the Arkansas River in which permeable <br /> sand and gravel alluvium overlies relatively impermeable bedrock of the Lower Member of the Pierre Shale <br /> (Tweto, 1979). <br /> The majority of the mine site is located on the north side of the Arkansas River where the prevailing <br /> groundwater flow direction is anticipated to south-southeasterly roughly reflecting the site topography with <br /> some influence from the bedrock topography. A small portion of the permit area is on the south side of the <br /> river where the prevailing groundwater flow direction will be north-northeasterly also reflecting site <br /> topography with some influence of the bedrock topography. Groundwater in the area is tributary to the <br /> Arkansas River located on the south part of the site. Local groundwater levels and flow directions are likely <br /> influenced by: <br /> • The Arkansas River is located on the south part of the site. For the majority of the year, the river <br /> acts like a drainage way maintaining groundwater elevations higher than water elevations in the <br /> river. During periods of high runoff, usually in the spring, river water levels will locally recharge the <br /> alluvial aquifer. <br /> • The Saint Charles River is south of and tributary to the Arkansas River and encroaches on the <br /> mine at its confluence with the Arkansas. The Saint Charles River will behave in a manner similar <br /> to the Arkansas River acting like a drainage way for the majority of the year and locally recharging <br /> groundwater levels during periods of high run off. <br /> • The Excelsior Ditch traverses the western and northern parts of the site before leaving the north <br /> part of the site. The ditch will act like a drain during the non-irrigation season maintaining <br /> surrounding groundwater levels at or near water levels in the ditch. During the irrigation season, <br /> the ditch may serve as a source of recharge to the alluvial aquifer. <br /> • Irrigation is practiced in the area. Applied irrigation that is not lost to evaporation and transpiration <br /> will likely recharge the alluvial aquifer. <br /> • Minor losses to the groundwater regime will occur due to evaporation of Thunderbird Lake and the <br /> unnamed ponds on the west part of the site. Evapotranspiration will also result in minor losses to <br /> the groundwater regime. <br /> • Alluvial Wells: Local alluvial wells are present in the area. When pumping, groundwater will be <br /> drawn to the well(s). <br /> Martin Marietta Materials—Thunderbird Sand and Gravel—MLRB 112 Permit Application <br /> Exhibit G-3 <br />