A mining company wishes to install some water supply wells

A mining company wishes to install some water supply wells to provide water for their operation. One pumping well has been completed and they are seeking approval for a second well. A Farmer on an adjacent property owns an artesian well. This is a well that flows freely as the potentiometric surface is greater than the land surface. The new well can only be installed if it will not adversely impact the farmers well. A schematic for this is presented in Figure 1. Assume the aquifer is homogeneous and isotropic (show working for whole question). See Figure and Table 1 on page 2.

a. A pumping test was conducted over 100 days with a pump rate of 700 Litres per minute (700 L/min). Drawdowns have been observed in the monitoring well and are presented in Table 1 (on page 3).
i. Calculate the radial distance between the pumping well and the observation well
ii. Calculate the transmissivity of the aquifer (4 marks)
iii. Calculate the storativity of the aquifer (4 marks)

b. The mining company plans to pump both the old and new wells at 700 L/min for a period of 10 years.

i. Calculate the radial distance between the existing pumping well and the artesian well

ii. Calculate the radial distance between the proposed pumping well and the artesian well
iii. Calculate the drawdown at the artesian well due to pumping from the existing well after 10 years
iv. Calculate the drawdown from the at the artesian well due to pumping the proposed well after 10 years (4 marks)
v. Calculate the combined drawdown at the artesian well from pumping both wells after 10 years.
vi. Would the artesian well still flow at the end of the 10 year period (i.e. would the potentiometric surface be greater than land surface)?
vii. At what rate could the two wells be pumped if the acceptable level of drawdown at the artesian well was 5m after 10 years?

6. A mining company wishes to install some water supply wells to provide water for their operation. One pumping well has been completed and they are seeking approval for a second well. A Farmer on an adjacent property owns an artesian well. This is a well that flows freely as the potentiometric surface is greater than the land surface. The new well can only be installed if it will not adversely impact the farmers well. A schematic for this is presented in Figure 1. Assume the aquifer is homogeneous and isotropic (show working for whole question). See Figure and Table 1 on page 2.

a. A pumping test was conducted over 100 days with a pump rate of 700 Litres per minute (700 L/min). Drawdowns have been observed in the monitoring well and are presented in Table 1.

i. Calculate the radial distance between the pumping well and the observation well.

ii. Calculate the transmissivity of the aquifer.

iii. Calculate the storativity of the aquifer.

b. The mining company plans to pump both the old and new wells at 700 L/min for a period of 10 years.

i. Calculate the radial distance between the existing pumping well and the artesian well.

ii. Calculate the radial distance between the proposed pumping well and the artesian well.

iii. Calculate the drawdown at the artesian well due to pumping from the existing well after 10 years.

iv. Calculate the drawdown from the at the artesian well due to pumping the proposed well after 10 years.

v. Calculate the combined drawdowm at the artesian well from pumping both wells after 10 years.

vi. Would the artesian well still flow at the end of the 10 year period (i.e. would the potentiometric surface be greater than land surface)?

vii. At what rate could the two wells be pumped if the acceptable level of drawdown at the artesian well was 5m after 10 years?

Figure 1 – Schematic for the scenario in Question 6. Numbers in brackets represent the x and y locations of the wells.

Table 1: drawdown data from the observation well based on the well being pumped.