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Huddltiton -Berry <br />• �'iL` T�r.'nia Tt.• - }tIC <br />Foundations on rock are not susceptible to frost heave. However, it is <br />recommended that the bottoms of foundations above structural fill be at least 36- inches <br />below the final grade for frost protection. <br />I3r die <br />HBET understands that the size of the proposed bridge, locations of abutments, <br />etc. have not yet been determined. As a result, recommendations for bridge foundations <br />will be developed in the future. However, based upon the results of the subsurface <br />investigation, deep foundations are likely to be the preferred alternative. <br />PuMp Station <br />HBET understands that the proposed pump station will include a metal building <br />Iess than 2,000 square -feet in size. In addition, HBET understands that a slab foundation <br />is anticipated. In general, a slab foundation is appropriate based upon the nature of the <br />proposed construction and subsurface conditions. However, thick fill materials were <br />encountered in the borings. Therefore, in order to reduce the potential for excessive <br />differential settlements, it is recommended that the foundation be constructed above a <br />minimum of 36- inches of structural fill. <br />In general, due to the presence of coal and other deleterious materials, the existing <br />fill materials are not suitable for reuse as structural fill. Imported structural fill should <br />consist of a granular, non - expansive, non -free draining material such as pit run, crusher <br />• fines, or CDOT Class 6 base course. However, if pit -run is used as structural fill, a <br />minimum of six inches of Class 6 base course or crusher fines should be placed on top of <br />the pit -run to prevent large point stresses on the bottoms of the foundations due to large <br />particles in the pit -run. <br />Prior to placement of structural fill, it is recommended that the bottom of the <br />excavation be proofrolled to identify any soft or weak materials. Soft or weak materials <br />should be removed and replaced with structural fill. In addition, geotextile and/or <br />geogrid reinforcement may be necessary to stabilize soft areas. HBET should be <br />contacted to provide specific recommendations for subgrade stabilization based upon the <br />actual conditions in the bottoms of the excavations. <br />Structural fill should extend laterally beyond the edges of the foundation a <br />distance equal to the thickness of structural fill. Structural fill should be moisture <br />conditioned, placed in maximum 8 -inch loose lifts, and compacted to a minimum of 95% <br />of the standard Proctor maximum dry density for fine grained materials or 90% of the <br />modified Proctor maximum dry density for coarse grained materials, within f2% of the <br />optimum moisture content as determined in accordance with ASTM D698 or D1557C, <br />respectively. Pit -run should be proofrolled to the Engineer's satisfaction. <br />For foundation building pad preparation as recommended with structural fill <br />consisting of imported granular materials, a maximum allowable bearing capacity of <br />1,500 psf may be used. In addition, a modulus of subgrade reaction of 250 pci may be <br />. used for structural fill consisting of pit -run, crusher fines, or base course. It is <br />recommended that the bottoms of exterior foundations be at least 36- inches below the <br />final grade for frost protection. <br />W.12009 ALL PROIEC7S'00156 - RitYi City Consultams InC A4 56-000t New Elkt200 - Gw`.00456 -0004 R082410.&C 5 <br />