GENERAL41775 - Laserfiche WebLink

Home Browse Search

• -II- • five year mine plan are also the total cumulative hydrologic impacts. A. Surface Water Surface water monitoring has identified changes between the upstream monitoriny site (above mine) and the downstream monitoring site (below mine) on Tuttle Draw. Flows in Tuttle Creek increase an annual averaye of 11U% (based on 19811, 1981 data) from the upstream site (S41 N-1) to the downstream site (SW IJ-3)as identified on Exhibit 7-2 of the application. Part of this increase can be attributed to the fact brat the watershed drainage area increases between the two sites. However, the major reason for the increase appears to be an unnatural source of contributing water. Flaw data from the tributaries within the permit area reveal that discharge monitoring point~UUl contributes the majority of flow for most of the year. field visits to the mine revealed that the source of the water is irrigation return flows. The lands north and northwest of the permit area are intensely flood irrigated primarily with water from the San Miguel River. Irrigation return flows (interflow) are intercepted by the mine pits and are pumped into the Tuttle Draw drainaye. This flow phenomenon is significant in two ways. The irrigation return flows dilute the mine affected waters as well as the natural Tuttle Draw flows. And secondly, the irrigation return flows serve as an unnatural source of water that becomes affected as it passes through the mine pits and spoils. The irrigation return flow water is, very high in total dissolved solids and nitrate. This ~rieans that baseline water flowing tlirougl~ the mine area already has a poor water quality. This unnatural volume of water flowing through the mine also increases the potential for leaching of spoil material. Nlthough it is recognized that this condition exists, insufficient data exists to quantitatively determine the precise magnitude of the increase. To help monitor the impacts of the irrigation return flows, Peabody Coal Company has proposed to visually monitor the quantity of pit inflow on a monthly basis and to monitor the quality of the inflow on a quarterly basis for those parameters listed in attachment R of the permit application.