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Is"!.7 , ~ April 1, 1997 Mr. Ed McDowell Flatiron Companies P. O. Box 229 Boulder, Colorado 80306 Subject: Levee at Deepe Farm Pit Boulder, Colorado Job No. 25,385 Mr. McDowell: Enclosed are the results of our field and laboratory investigation we have completed to date for the levee. Figure 7 shows the maximum section of the levee of Station 122+00. We have summarized our completed analyses on the enclosed drafts of the partially completed forms that will eventually be a part ofthe submittal to FEMA. In summary, our preliminary opinions that the embankment meets the FEMA certification criteria is continuing to be confirmed as our analyses are being finished. Figure I shows the locations of our test holes and test pits. Figures 2 through 6 are the summary logs of our test holes and test pits and the results of our field permeability tests. Figure 8 shows the typical gradation of the levee fill and Table II shows the summary of the percents compaction we calculated at the density test locations. Table I shows the results of our laboratory tests. The test pits TP-1 through TP-3 were drilled (excavated) with a large pier hole drilling rig using a 42-inch diameter auger. The levee fill was very rocky and the rocks were numerous and close together. Our inspection of the test pits revealed the rocks were embedded in a densely compacted, clayey, sand matrix and it was impossible to pry the rocks loose without loosening the matrix when we dug the holes for the sand cone density tests. The "pilot hole" for the nuclear gauge probe had to be advanced by driving a pointed steel rod into the ground with a sledge hammer. Review of the gradation test results (Figure 8) of two typical samples of the levee fill shows that the levee fill is quite rocky and the samples had 40% to 45% larger than the 1/4 inch size. Review of the percents compaction in Table II show a range for the 15 tests (two of which were in the foundation ground at the bottom of the fill) 75 percent to 103 percent. In our judgment these test results are not reflective of the effort it took to excavate the test pits or the density of the fill as evidenced by the difficulties in excavating for the sand cone tests or advancing the "pilot hole" for the nuclear gauge. In our opinion, the levee fill is well compacted but CTL/THOMPSON, INC. CONSULTING ENGINEERS 1971 WEST 12TH AVENUE. DENVER. COLORADO 80204 . (303) 825-0777 .