Method and apparatus for impounding fluids

An impoundment pond comprising:

• earth walls forming a cavity in the earth, said cavity having sloped sidewalls and a bottom wall, said cavity having an upper level,
• a relatively thin first plastic sheet contiguous to said earth side and bottom walls,
• a pervious layer on said relatively thin first plastic film,
• means for determining the degree of seepage into said pervious sand layer from said impoundment pond,
• said means for determining including a system of drainage pipes in said pervious layer, a self-starting pump connected to said drainage system for pumping fluids from between said first and second plastic sheets, means for monitoring operation of said pumps to determine seepage from said impoundment pond,
• a relatively thick second plastic sheet, said second plastic sheet being substantially thicker than said first plastic sheet and lying on the surface of said pervious layer,
• a protective clay layer on said relatively thick second plastic sheet, and
• a standpipe having an upper end and lower end with said upper end projecting above said upper level of said cavity and said lower end being sealingly coupled through said protective layer to said relatively thick second plastic layer and projecting into said pervious layer.