1985-12-22_HYDROLOGY - M1984049 - Laserfiche WebLink

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impermeability of the tailings in this area. Subsequently • the decant pond level continued to rise and ultimately this injection well became inundated.. The tailings in this area of the pond are visibly higher°;.'n slimes content. Injection flows at each well diminished with time due to saturation of the tailings and partial plugging of the well bores with fine particulate suspended in the injection fluid. On September 26th the 4" 5DR casing was replaced with slatted 1 1/4/" pvc as previously discussed. The flow rates increased dramatically in pattern 1, (M1A, M1B and M1C), which is located at the east and sandiest part of the pond. Injection continued on a continuous basis until 23:30 hours on September 28th, by which time a total of 18701 gallons had been injected into the eight wells. All injection wells including the original 75 foot offset (I-3) were jetted to ascertain that all the dye had been dissolved and had migrated away from the well bare, which proved to be the case. Injection rates were the highest at the east side of the pond and diminished to the west, reflecting the increasing slimes content of the tailings in a westward direction. Steady state flows ranged from over 30 gph at well M1A to to 3.5 gph at M3A. The flow rates are summarized in Table No.2 in the subsequent section. • The flow rates were determined by use of a stopwatch and calibrated container. As there was but one flaw meter available, the injected volume for each well is estimated, on the basis of the flow rates. Assuming 30% voids and a cone of impression having a radius of 10 feet and its apex at the base of the injection well, the theoretical volumes at breakthrough were calculated for each monitor-injection well pair. Table No.l: Injection volumes; Gallons Well No. Volume Infected M1A 3582 M1B 3891 M1C 2364 M2A 1962 M2B 1087 M2C 2837 M3A 1345 M3B 1633 • -8- Theoretical Volume at Breal<throu9h 3760 3760 3524 3995 4230 1880 1645 940 ~2--,..... , a~