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Farth Engineering ConSLLhants.LLC <br /> EEC Project No. 1122096 <br /> Signal Reservoir Improvements <br /> August 5.2015 <br /> Page 1-4 <br /> It is recommended any vegetation within the limits of the pond configuration be stripped and <br /> removed It is anticipated that excavation of the pond could be accomplished by conventional <br /> type excavation equipment, however specialized or rubber tired equipment may be necessary <br /> when approaching the bottom of the "new/revised" reservoir bottom due to the presence of <br /> groundwater and/or the presence of a possible perched surface water condition. Special <br /> precautions may be required to maintain a working platform at the bottom of pond due to the <br /> potential for soft/compressible conditions at or near the groundwater and/or perched surface <br /> interface. <br /> The berms/embankments surrounding the pond should be lined as part of the wetted perimeter <br /> with an approved earthen liner material. Approved materials used in the earthen <br /> liner/embankment should be placed in maximum 9-inch thick loose lifts, adjusted in moisture <br /> content, and compacted to at least 95% of the materials' maximum dry density as determined in <br /> accordance with ASTM Specification D698. The moisture of the liner materials should be <br /> adjusted to be within the range of f2% of standard Proctor optimum moisture at the time of <br /> compaction. All earthwork/compaction activities should be field verified/approved by means of <br /> field density testing procedures and visual observations. The approved liner material, when <br /> compacted to at least 95% of the materials' maximum dry density should have a coefficient of <br /> permeability of 1 x 10' cm/sec or slower. The liner thickness is a function of the material used to <br /> construct the earthen embankments, the material's in-situ permeability characteristics, as well as <br /> the piezometric head or volume of water planned for short and/or long term purposes. <br /> Based on our understanding of the proposed water storage reservoir design concept and our <br /> experience with materials with similar properties, we expect the on-site overburden cohesive <br /> soils and underlying bedrock material, (processed to at least 2-inch minus nominal particle size), <br /> would be suitable for use as a low permeability earthen embankment material as intended. <br /> Variations and characteristics of the bedrock may exist across the pond. Seepage could occur <br /> through interbedded sandstone seams. <br /> Care should be taken to provide a consistent, uniform low permeability cohesive material for use <br /> as the earthen liner. The materials' permeability should continually be evaluated during <br /> construction to verify acceptance, and upon completion of the pond, in-situ flex-wall <br /> permeability tests (ASTM Specification D5084) should be performed for final compliance <br /> purposes. <br />