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S <br />A11 <br />EEC Project No. 1082030 <br />ASCI - Tumpike Reservoir <br />May 5, 2008 <br />Page 15 <br />Earth Engineering Consultants, Inc. <br />Care should be taken to provide a consistent, uniform low permeability cohesive material for <br />use as the earthen liner. In our experience, lean clay soils and siltstone/claystones bedrock <br />materials similar to the subsurface conditions encountered on-site have a high probability <br />that the material would be suitable for development for use as an earthen liner. In general, a <br />typical coefficient of permeability for lean clay soils would be on the order of 1 x 10-7 cm/s or <br />lower when compacted to at least 95% or greater of the material's standard Proctor <br />maximum dry density (ASTM D 698). <br />For any proposed intake and/or outlet pipes, or any other intrusions penetrating the cohesive <br />liner embankments, the pipes should be properly bedded and backfilled with approved, <br />relatively impervious cohesive soils. The intrusions/pipes should be surrounded by a <br />minimum of 2-feet of relatively impervious cohesive materials having a coefficient of <br />permeability of 1 x 10-7 cm/sec. or slower when properly compacted as described herein. The <br />backfill should be compacted to a minimum of 95% of the material's standard Proctor <br />density as determined by ASTM D698. Anti-seep collars should be placed around all inlet <br />and outlet pipes. <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 <br />size), would be suitable for use as a low permeability earthen embankment material and <br />deepened core trench as intended. The materials permeability should continually be <br />evaluated during construction to verify compliance. Variations and characteristics of the <br />bedrock may exist across the pond. Seepage could occur through interbedded sandstone <br />seams. <br />GENERAL COMMENTS <br />The analysis and recommendations presented in this report are based upon the data obtained <br />from the soil borings performed at the indicated locations and from any other information <br />discussed in this report. This report does not reflect any variations, which may occur <br />between borings or across the site. The nature and extent of such variations may not become