|
During periods of no irrigation, Well GW-N1 S showed a slight decrease in calcium and a decrease
<br />in magnesium and sulfate, with increases in sodium, bicarbonate and chloride. Well GW-N18
<br />showed a slight decrease in magnesium, slight increases in sodium and bicarbonate and increases
<br />in calcium and sulfate. Well GW-N21 showed a slight decrease in calcium, a slight increase in
<br />bicarbonate, increases in magnesium, sodium and sulfate and a large increase in chloride.
<br />A range in pH values from 7,3 to 7.8 were measured at the four overburden wells. The mean pH
<br />values for wells GW-N15, GW-N18, GW-N18PI, and GW-N21 are 7.5, 7.61, 7.5 and 7.54,
<br />respectively
<br />There appeared to be some seasonality to the overburden water chemistry at the New Horizon 2
<br />mining area. In comparing spring versus fall chemistry, alkalinity, bicarbonate, chloride, potassium,
<br />sodium, sulfate and TDS levels tended to decrease in the fall. In comparing fall versus winter
<br />chemistry, alkalinity, bicarbonate, chloride, potassium and sodium levels increased and pH
<br />decreased in the winter. Ih comparing summer versus winter chemistry, alkalinity, bicarbonate,
<br />chloride and sodium levels increased and calcium levels decreased in the winter.
<br />In addition to chemical seasonality, there were some overburden chemical trends during the
<br />irrigation season with time. Well GW-N18 showed a decrease in calcium and an increase in
<br />sodium, bicarbonate, sulfate and TDS levels
<br />Well GW-N18 water exceeded the CWQCC agricultural standards forfluoride and manganese and
<br />the water at Wells GW-N15 and GW-N21 exceeded the manganese standard. In comparison to
<br />livestock drinking water standards, Well GW-N 15 water exceeded the magnesium, sulfate and TDS
<br />standards and Well GW-N18 water exceeded the fluoride standard. Well GW-N21 water was
<br />suitable for use as livestock drinking water and water at well GW-N18P1 was suitable for both
<br />agricultural and livestock use. Measurable trace element concentrations in the overburden aquifer
<br />included aluminum, arsenic, boron, cadmium, cobalt, fluoride, iron, lithium, manganese, nitrate,
<br />selenium, vanadium, silverand zinc. The highest concentrations of cadmium, nitrate, selenium and
<br />silver were measured in the overburden,aquifer at the New Horizon 2 mining area.
<br />Three wells (GW-N14, GW-N17P1 and GW-N20) monitored the Dakota coal aquifer wafer quality
<br />in the New Horizon 2 mining area. The individual water quality analyses for the Dakota coal aquifer
<br />Revised 25 JUI 2002 2.04.7-14
<br />
|