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M99012GE <br />6/22/99 <br />Page Two <br />material is placed in relatively horizontal layers and compacted <br />during placement. This would indicate that the horizontal layers <br />in the other test borings which correspond to the layer from which <br />the low density sample was obtained in test boring 3 were compacted <br />to at least ninety (90) percent or greater relative compaction. <br />The higher level of relative compaction of the samples immediately <br />above and below the questionable sample and relative compaction <br />results from samples in the other two (2) test borings at the same <br />elevation as the questioned sample suggests the likelihood that the <br />sample in test boring 3 at a depth of about four (4) to five and <br />one-half (5-1/2) feet may have been anomalous and does not seem <br />representative of the actual in-place density for any but a very <br />small area. <br />The second sample with a calculated relative compaction less than <br />ninety (90) percent was obtained from test boring 3 at a depth of <br />about six and one-half (6-1/2) to eight and one-half (8-1/2) feet. <br />The sample was the bottom approximate four (4) to six (6) inch <br />portion of the second foot of the sample interval. If the sample <br />density of the entire last foot of the sample interval was used to <br />calculate the average density of the one (1) foot interval the <br />average calculated relative compaction would be ninety (90) <br />percent. <br />As above, the third sample was the top approximate four (4) to <br />six (6) inch portion of the first one (1) foot of the sample <br />obtained from a depth of about nine (9) to eleven (11) feet. If <br />this sample density was calculated using the sample obtained from <br />the entire first foot of the sample interval the average calculated <br />relative compaction for the first foot of the sample interval would <br />be ninety-two (92) percent relative compaction. <br />We feel that combining the total sample for the entire one (1) <br />foot interval of the above two (2) samples discussed would provide <br />a more representative calculation of the relative compaction for <br />that foot interval of sampling. <br />Based on our review and assessment of the density test results <br />and calculated relative compaction of the samples obtained from our <br />test borings we do not feel that sufficient evidence has been <br />obtained to determine that the lower portion of the GOB pile was <br />not compacted in accordance with the requirements for compaction of <br />the GOB pile. <br />Although three (3) samples were obtained with calculated relative <br />compaction less than the required ninety (90) percent the samples <br />obtained surrounding at similar elevations within the GOB pile and <br />adjacent to the low density samples indicated generally higher <br />Lambert ana ~,s,~ociate,s <br />COnSUU~~~G GEODE C~NiC•l ENGIN EE AS ~w0 <br />