folding the gas bag in such a manner so that it easily inflates and completely seals the borehole application_number US 39332603 A description a device embodying the principles of this invention is shown in fig1 and is broadly designated by the reference numeral 10 gas bag 10 typically comprises sodium bicarbonate 12 contained within a pva bag 14 as shown in fig3 and acetic acid 16 contained within an hdpe bag 18 as shown in fig2 both the pva bag 14 and the hdpe bag 18 are contained within a nylon pe bag 20 which is folded and bundled together by bands 22 tab 24 is coupled with nylon pe bag 20 gas bag 10 is constructed by securing the hdpe bag 18 to one end of nylon pe bag 20 and placing the pva bag 14 at the other end as shown in fig1 and 5 a tab 24 is secured to gas bag 10 for lowering the bag into a borehole referring to fig4 a fold in nylon pe bag 20 is made inwardly along a dotted line 26 and a fold is made outwardly along a dotted line 28 next a fold is made inwardly along a dotted.