|
• Trace elements in the Dakota coal wells were measured. Well GW-N14 water exceeded the
<br />CWQCC agricultural standards foraluminum, iron, fluoride, manganese and pH; Well GW-N17P1
<br />waterexceeded the pH standard; and Well GW-N20waterexceededthe iron, manganese and pH
<br />standards. In comparison to livestock drinking waterstandards, Well GW-N 14 water exceeded the
<br />aluminum and fluoride standards and Well GW-N20 exceeded the aluminum standard. Measurable
<br />trace element concentrations in the Dakota coal aquifer included aluminum, arsenic, beryllium,
<br />boron, cadmium, chromium, cobalt, copper, fluoride, iron, lithium, manganese, nickel, nitrite, nitrate,
<br />vanadium and zinc. The highestconcentrations ofaluminum, beryllium, boron, cobalt, fluoride, iron,
<br />lithium, manganese, nickel, nitrite and zinc were measured in the Dakota coal aquifer at the New
<br />Horizon 2 mining area. Also, the lowest pH values were recorded in this aquifer.
<br />Three wells (GW-N13, GW-N16 and GW-N19) monitored the underburden aquiferwaterquality in
<br />the New Horizon 2 mining area. The individual waterquality analyses forthe underburden aquifer
<br />wells in the New Horizon 2 mining area are presented in Peabody Appendix 7-4. Thewell locations
<br />are shown on Map 2.04.7-1.
<br />The three underburden monitoring wells exhibited three watertypes during periods of irrigation. Well
<br />GW-N13 showed calcium magnesium sulfate water type, Well GW-N13 showed a calcium
<br />magnesium sulfate watertype, Well GW-N16 showed a sodium bicarbonate watertype, and Well
<br />GW-N19 showed a sodium calcium magnesium bicarbonate sulfate water type. During the
<br />non-irrigation periods the only water type change was at Well GW-N19 where the water type
<br />became a sodium magnesium calcium sulfate bicarbonate. All three wells increased in TDS during
<br />non-irrigation periods. The greatest increase in TDS, 220 mg/I, occured at Well GW-N19. Mean
<br />TDS levels forthe three underburden wells (GW-N13, GW-N16 and GW-N19) during periods of
<br />irrigation and no irrigation were 2,592 and 2,632 mg/I, 1,059 and 1,079 rag/I, and 1,204 mg/I and
<br />1,424 mgll, respectively.
<br />During periods of no irrigation, Well GW-N13 showed slight increases in calcium, sulfate and
<br />chloride levels and slight decreases in magnesium and sodium levels; Well GW-N16 showed a
<br />decrease in magnesium and slight increases in sodium, bicarbonate and chloride levels; and Well
<br />GW-N19 showed a slight decrease in bicarbonate and increases in calcium, magnesium sodium,
<br />• (REVISED6/28/01) 2.04.7-16
<br />
|