Recovery and control system for leachate collection

A system for withdrawing and collecting a flowable liquid material from a landsite having at least one in-ground well, a collection system for collecting the withdrawn liquid material, and a source of pressurized gas, said system comprising:

• a gas-operated pump submersible in said in-ground well, said pump including:
• a generally hollow pump body having a generally hollow interior and an inlet means including an inlet check valve for providing
• substantially one-way fluid communication from the in-ground well into the pump body interior, and outlet means including an outlet check valve for providing substantially one-way fluid communication from the pump body interior to the collection system;
• and
• a discharge tube disposed within said pump body in a spaced relationship therewith and having an open end, said discharge tube further having a discharge end in sealed fluid communication with said outlet means;
• a liquid collection tank and means for conveying the liquid material from said gas-operated pump to said collection tank;
• and
• gas control apparatus for controlling the operation of said gas-operated pump, said gas control apparatus including:
• well level sensing means for sensing the level of the liquid material in the in-ground well, said well level sensing means including a static head conduit having an open end extending below the surface of said liquid material in the in-ground well and a second end in fluid communication with a source of a first measuring fluid, said well level sensing means including means for supplying said first measuring fluid to said static head conduit at a pressure sufficient to force a portion of said first measuring fluid out of said open end against static head of the liquid material, and means for measuring and controlling the pressure of said first measuring fluid in order to determine the level of the liquid material in the in-ground well;
• actuation means for selectively actuating said gas-operated pump in response to the sensing of a predetermined high liquid material in the in-ground well and for selectively deactuating said gas-operated pump in response to the sensing of a predetermined low liquid material level in the in-ground well;
• timer means for sequentially and pulsatingly pressurizing and depressurizing said pump body interior for respective first and second time periods during said actuation of said gas-operated pump, the liquid material in said pump body interior being displaced and forcibly discharged through said discharge tube and said discharge means when the gas in said pump body interior is pressurized, and the liquid material in said in-ground well being allowed to flow into said pump body interior when the pressure of the gas in said pump body interior is relieved;
• and
• tank level sensing means for sensing the level of the collected liquid material in the collection tank, and shut-off means for preventing actuation of said gas-operated pump in response to a predetermined high liquid material level in the collection tank, said tank level sensing means including a second static head conduit having an open end extending below the surface of said liquid material in the collection tank and a second end in fluid communication with a source of a second measuring fluid, said tank level sensing means including means for supplying said second measuring fluid to said second static head conduit at a pressure sufficient to force a portion of said second measuring fluid out of said open end of said second static head conduit against the static head of the liquid material, and means for measuring and controlling the pressure of said second measuring fluid in said second static head conduit in order to determine the level of the liquid material in the collection tank.