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<br /> <br />by 2 feet deep prior to addition of the drain material. (The remainder of the secondary <br />underdraln will be constructed as shown on Detail D; 14 of the Design Drawings.) <br />The granite rock placed in this drain is, as noted above, derived from the area of granite <br />approved via your letter of July 13, 1994. It has been screened to remove oversized <br />(>3/4") and undersized (<3/8"). The material will also serve as bedding for the three drain <br />pipes in the central drainage system, although some additional fines may be blended into this <br />same material when used for underdraln pipe bedding -which material will still be held to <br />specifications. <br />It was our understanding that, under the circumstances of no flow noted during all <br />inspections, that Dr. Pendleton believed the material was suitable -provided the fines were <br />minimized. <br />While on site today and during placement of this material, we noted that the approved <br />material had been placed in the downgradient portion (approximately 600 feet) of the <br />secondary underdraln; however, the same durable granite but which contained substantially <br />more fine material (less than the minus 3/8" fraction) had been placed in the upgradient <br />portion of the secondary underdraln. Ames construction was notified that the fill placed in <br />the upgradient portion was not acceptable and should be removed and replaced with the clean <br />fill described here. Ames did so remove the material (stockpiling it for pipe bedding <br />material) and Golder documented the removal and replacement of the unsuitable fill during <br />the same shift (Thursday day shift) during which it was noted. <br />This modification was proposed and approved by the Design Engineer (Golder) for only this <br />particular secondary underdraln located in the most southeast drainage of the Phase 1 Valley <br />Leach Facility (the drainage valley that extends from the crest between the Wilson Creek <br />drainage and Arequa Gulch from the vicinity of the haul road to the soil stockpile as that <br />road crosses that hill crest). <br />Again, the purpose of this letter is to obtain your concurrence with the field approval and <br />opinion from Dr. Pendleton. We would appreciate receiving concurrence immediately <br />because the material will be covered with geotextile tommorrow. If any additional <br />information is required, please do not hesitate to call. <br />Attachment (1): a/s <br />2 <br />