| 摘要 |
<p>A cavity is excavated in the earth with preferably sloping sidewalls (11-14) and a first impervious barrier or layer (20) of plastic film or sheet. One or more self-starting pumps (25) are placed at intervals along the slope and embedded in a pervious layer, such as sand, of from one to three feet in thickness. An inner impervious layer (30) which, in a preferred embodiment, is substantially thicker than the outer or first impervious layer (20) is laid over the sand and then a final layer (31) or cap of clay over the inner impervious plastic layer (30). Any seepage or leakage through the inner impervious layer (30) caused by a tear or imperfection in the plastic, flows down to the self-starting monitoring pumps (25) which, upon sensing the flow, turns itself on. The invention includes sensing the time of operation of the self-monitoring pump (25) to determine the degree of seepage. </p> |
