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77-423 <br />George Jackson F, Associates -2- August 31, 3977 <br />Percolation tests were run <br />to a depth of 36 inches, in <br />normally used on lots that <br />In accordance with standard <br />permitted to soak overnight <br />in 6-inch diameter holes, drilled <br />accordance with procedures <br />will be developed residentially. <br />procedures, the holes were <br />before conducting the tests. <br />Each of the borings were probed immediately after completion <br />to check for the presence of groundwater. <br />RESULTS: <br />The log of soils encountered in the borings and the water <br />level observations are shown on the attached Log of Bor.;ig <br />sheets. <br />Boring B-1 encountered a sandy clay glacial till from the <br />surface to the 11-foot depth, underlain by coarse alluvium <br />sands and silty sands to the 20-foot termination depth in <br />this boring. <br />Boring encountered a silty clayey sand glacial till from <br />the surface to the 4-foot depth, which was immediately <br />underlain by a clayey silt lacustrine deposit from the 4 to <br />the 13-foot depth. Sandy clay glacial till was then encoun- <br />tered to the 20-foot termination depth in this boring. <br />The balance of the borings, B-3 through B-8, all encountered <br />glacial tills consisting of silty clayey sands in the upper <br />Iportions of the borings to sandy clays at depth. <br />In probing the borings immediately after completion, it was <br />noted that cave-ins had occurred in all of the borings <br />betty and 18�-foot de the he exception being <br />ring B-1 where roun ncounter 6-foot <br />�dep pproxima e y hours later, a rec eck of eac <br />re holes indicated no groundwater occurrence in borings <br />B-2 and B-8. red at a depth of 7 feet in <br />boring B-5 14 feet in boring B- 15 feet in boring B-7, 16 <br />feet in bor at the 17-foot depth in <br />boring B-6. Water level readings vary considerably, ranging <br />from elevation 936, as indicated by boring B-6, taken in the <br />far southeastern corner of the site in what appears to be <br />the lowest area on the site, to elevation 988, indicated by <br />boring B 1 and taken in the upland area in the southwestern <br />portion of the site. These water level variations can be <br />attributed to several factors. 1) The undulating topographic <br />features of the site indicate that water levels are following <br />the contours and subsequent drainage patterns developed in <br />this area. 2) Because of the cohesive nature of the soils <br />encountered, considerable time is required in order for the <br />groundwater to stabilize in the borings. It does not appear <br />BRAUR" <br />ENGINEERING TESTING <br />