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APR 7 '95 10:29 FROM AM ENG TST ST PAUL TO 97843462 <br />PAGE.006 <br />AET #95-1343 - Page 5 <br />CLule oI Pwt M vemen <br />We judge that the majority of the past ground movements would be associated with consolidation <br />of the peat swamp deposits, largely due to the weight of the overburden fill. Because the fill <br />includes some organic soils, we anticipate some compression of the fill has also occurred, <br />although to a significantly lesser degree than the major swamp deposit- In addition to the soil <br />consolidation, the potential for soil frost heaving and ice lense formanon may be contributing <br />to the ground movement problem. <br />Although our evaluation lacks site specific laboratory testing, we estimate that future park <br />settlements without additional regrading should be about 3" to 4" over the next 20 years. Local <br />frost movements may also occur, which would add to the surface irregularity. Minimal grading <br />may be needed to attain a reasonably level playing surface, and if grading re1nains within about <br />'fi' of the existing surface, surface seudt=nts should remain within about 1fi' . Variation of load <br />due to the minor grading may result in the need for on-going maiia '+�..a=. Also, this type of <br />future correction would not improve surface stability (if this is important). In the event you <br />wish to improve future performance beyond that described, several options could be considered. <br />These are as follows: <br />5uxr-haitge dption <br />In order to reduce the consolidation potential of the swamp deposits, it would be possible to <br />place a surcharge upon the athletic field area thereby precompressiug the materials prior to final <br />grading. To reasonably surcharge the materials, we would suggest a minim� surcharge height <br />of 3' to 4' above the eventual final grade, and allowing the surcharge to rest for several years <br />prior to removal. It would be possible to provide a level surcharge and sod the land for athletic <br />field use during this time, although movements should be expected. If such movements were <br />deemed tolerable, you could elect to leave the surcharge in-place and use the field "as is". <br />However, we suspect the primary and secondary consolidation which would result would be <br />