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Aug-21-96 O6:38A Lincoln DeVore of Grd Jct 970-242-1561 P.11 <br />di Cfer•ent.ial movement of the emhanlcmetrt occurred, Simi Lar• t.o :t <br />slope failure or foundation failt:re. <br />As a result of the further test.inq of <br />the native soils, particularly the deeper, weathered claystones, <br />one significant soil property became Apparent. Some of the c1Ay's <br />within the native soils exhibited high to very high swelling <br />car}~acity. Native samples of these soils exhibited swelling of <br />Approximately 1.5996 of expansion when wetted at an at~plie~i luacl <br />of 921 psf. This sample required approximately 2026 psf to <br />c:omp:•ess tt;e specimen back to the origirtAl height. Two other <br />srtmples (TH #1 at 13' and TH #2 at 18'i were tested using ttre FHA <br />method and found to exhibit soil expansion of approximately l.2% <br />and 1.21A against a proving ring load of -1900 psf and 3700 t~sf, <br />respectively. Depending upon the assumptions used in interlrret- <br />ing t}:ese test results, the swelling pressures exhibited by tiro <br />Fil,1 meter appear to correspond quite well with the <br />consolidation/swell test, ASTyt D-2.135. <br />Based upon our field observation of tt~e <br />site, field testing ar•d laboratory testing of the simples, it is <br />our conclusion ttte embankment cracking was probably caused by <br />differential heaving of the underlying, relatively higtr expansive <br />claystones encountered below 13' from the emhanlcmer:C crest. It <br />is t,elieved the underlying, highly expansive claystones are being <br />progressive wetted from the interior portion of ±he Sediment Pond <br />towards the exterior portion. It is also helieved t}re consiruc- <br />tton of the existing embankment may- have partially- compacted the <br />lower embankment/alluvial soils encountered between S' to l2' <br />9 <br />