REV88366

• Permit No: C1981008
• IBM Index Class Name: Revision
• Doc Date: 9/29/1995
• Doc Name: Response to Adequacy Review
• Type & Sequence: TR24
• Media Type: D
• Archive: No

i ~
Approved Hydrological Monftoring Program
Table 15-7 summarizes various approved monitoring stes for both New Horizon 1 and New Horizon
2 mine areas. For New Horizon 1 Mine, these sites aze those approved under the permit previously
held by Peabody Coal and later revised by WFC. See Map 2.04.7-1 of New Horizon 2 Mine for
monitoring station locations.
Twelve groundwater wells will be monitored in New Horizon 1 mine area. They are listed in Table
15-7 as GW-Ni, GW-N3, GW-N4, GW-N8, GW-N9, GW-N10, GW-N11, GW-N24, GW-N25,
GW-N26, GW-N27 and GW-N28. Wells GW-N7 P1 and GW-N4R will be dropped from monitoring
as they duplicate the function of welts GW-N1 and G1N-N4.
AI! wells will be monitored on a monthly basis for water levels except wells GW-N10, GW-N26 and
GW-N28 which have historically remained dry. Field monitoring of these wells will be done on art
annual basis unless water is found.. These levels will be adjusted to mean sea elevation. Water
samples will be collected and analyzed for the parameters listed in Table 15-8 on an annual basis
for wells GW-N3 (underburdenj, GW-N4 (Dakota coal}, GW-N9 (overburden and coaq and GW-
N27 (spoil}. Annual samplings will be conducted in August.
There will be ten surface water monitoring stations in the New Horizon 1 Mine Area. Six of these
are NPDES stations (NPDES 001 through NPDES 006), two stations are in Tuttle Draw (SW-N1 and
SW-N3) and two aze spoil springs. Station SW-N4 in Tuttle Draw will be dropped since SW-N1
and SW-N3 adequately serve monitoring purposes of Tuttle Draw. Spoil Spring #2 will be dropped
since R duplicates Spoil Spring #1.
NPDES 001 station will be monitored on a weekly basis. The remaining surface stations are
monitored monthly for field parameters outlined in Table 15.7. Water samples will be collected and
analyzed for parameters listed in Table 15-8 on an annual basis.
A previously approved version of the permit had noted the possiblity of installing a surface water
monitoring site in the posdaw reclaimed area above County Road AA at the New Horizon 1 Mine.
This monitoring site was to be used to obtain surface water quality and flow data representative of
runoff from postlaw reclaimed areas for bond release purposes. Installation of this site could ony
occur after revegetation of the disturbed areas had been achieved. Since Pond 001 collects all this
runoff and this pond water is monitored on a weekly, monthly and quarterly basis, WFC proposes
that the previously mentioned surface monitoring site would not be required.
(Rev. 9/95) 15-19