Patent ID: 7896578

Claim:
An apparatus for evaluating underground contamination, the apparatus disposable in a borehole having a borehole wall, the apparatus comprising: a flexible first liner, defining a tube with a closed end, disposable by eversion in the borehole; a retrieval cable, attached to the closed end inside the tube, for retracting the liner from the borehole by inversion; and an absorbent member disposed upon the liner, the absorbent member comprising: an outer layer, comprising a flexible material of low permeability to water, for preventing immediate saturation of an absorbent material by ambient water residing in the borehole; the absorbent material disposed between the liner and the outer layer; wherein when the apparatus is at least partially everted in the borehole, at least a portion of the liner is urged toward the borehole wall by a fluid pressure inside said liner, and at least a portion of the absorbent member is pressed against the borehole wall by the portion of the liner, whereby any contaminants at the borehole wall are at least partially absorbed by the absorbent material; and a diffusion barrier, comprising a thin metal film, disposed between the liner and the absorbent material.