SITE INFORMATION AND CORRESPONDENCE

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~ _ r These were labeled XW in our original report to indicate that they were in- tended as extraction wells, as we anticipated a ground water problem. As it turns out, it appears that a ground water problem does not exist. These wells were relabeled as MW-8 and MW-9. Site Status: Itcm11: It is our opinion that MW-4S and 4D are definitely constructed properly and that representative samples can and have been taken from them. We will address your concerns about this well in the order they are presented (see drawing): CONCRETE ON AUGER FLIGHTS AT MW-4S: Well-4S was drilled after Well-4D, about 10 feet north. TD for 4S is 38 feet, while 4D TD's at 60 feet. 4D was drilled to 38 feet with a 24 inch bucket auger. A 12 inch blank steel surface casing was then centered in the hole and driven about six inches (6"). l� Bentonite pellets were placed around the annulus of the steel surface casing l from 38 to 35.5 feet. The annulus between the 24 inch diameter hole and the 12 inch casing (six inches (6") in width) was then filled with a five sack cement/ sand grout mixture from 35.5 feet to surface. 7 The Bentonite pellets were then dropped in the annulus between the 12 inch no'- diameter casing and the four inch (4") diameter PVC, in several lifts, auger hole e` and the 10 inch diameter Hallow Stem Auger hole was thus sealed twice with g Bentonite pellets. The seal is 2.5 feet thick outside the 12 inch diamet �p�� conductor casing and is eight feet (8') thick inside the conductor casing. `�' The next day, 4D was then re-entered with a 10 inch Hollow Stem Auger, inside the empty 12 inch casing, to 30 feet. It was then drilled with the 10 inch ! tool from 30 to 60 feet. A four inch (4") PVC well was then set in the hole, with screened interval from 50 to 60 feet. The sand pack was installed from 60 to 50 feet and then Bentonite pellets from 50 to 46.5 feet. Neat cement Bentonite grout with five percent (5%) Bentonite was tremied from 46.5 to scc surface. The annulus in this portion of the hole (38 to 60 feet) was three inches A 0r" ( ) wide around the four inch (4") diameter PVC casing. The concrete that was observed on the auger flights during drilling of MW 4S was probably cement water that migrated via Sand 1 over to the vicinity of MW-4S. The rigside geologist obviously used an improper term here; he did not see concrete (a cement-sand-gravel mixture), what he saw was some cement grout which was diluted with ground water (grey water). Since concrete was not used in the construction of either well 4S or 4D, it would be impossible to