2013-02-19_GENERAL DOCUMENTS - C1981014

Home Browse Search

Southfield C1981014: MT6 5 February 19, 2013 Hydrology An extensive review of both the ground water and surface water hydrology can be found in Sections 2.04.7, 2.05.6 and 4.05 of the permit application package. Below is a brief summary of the ground and surface water issues at the Southfield Mine. Ground Water Due to the extensive underground mining activities in the area, ground water baseline information was difficult to obtain. Trends for ground water were established and have been recorded since the mine opened as the Dorchester No.2 in the 1970's. Ground water flow is difficult to predict based on the tendency for the ground water to flood old workings in the area. Many residential wells have been drilled into the old abandoned workings and provide residents with water. In the mine area, evaluation of groundwater resources is based primarily on exploration drilling, records of ground water use, information on regional groundwater characteristics, monitoring information, inflow into underground workings at the Southfield Mine and historic information on abandoned workings. There are three categories of potential groundwater aquifers that occur in the permitted area: 1) the Trinidad Sandstone, 2) coals of the Vermejo /Raton Formations and 3) localized river alluvium. A detailed analysis of each of these aquifers is found in the Probable Hydrologic Consequences of the permit application package. All ground water flow into these three aquifers is the direct result of recharge collected from the Wet Mountains to the west. The water flow is structurally controlled by the Chandler Syncline and runs along the axis north to the Arkansas River where it discharges. The Chandler Syncline trends northwesterly. The Conte well is listed as being constructed in Township 70 West, Range 68 West in the Division of Water Resources -State Engineer's Office permit. The location of this well in the permit area needs to be confirmed and updated as necessary. Section 2.04.7 of the PAP discussed potential sources for alternative water supply in the unlikely occurrence that mining operations result in depletion groundwater reservoir. Colorado Division of Water Resources State Engineer's Office (DWR -SEO) requires that all monitoring wells be permitted with their office. EFCI maintains four (4) water monitoring wells: MW -16, MW -23, MW -NW, and MW -65. In accordance with Rule 2.03.10, the permittee shall provide a list of all other licenses and permits needed. All monitoring wells need to have permits with Colorado Division of Water Resources. The Division is currently reviewing water quality concerns, applicable standards, and the approved water monitoring program. Surface Water Surface water in the area flows from the Wet Mountains on the west to the plains on the east then bends northward toward the Arkansas River valley. Most of the streams in the area are ephemeral, flowing in response to snowmelt and intense rainfall events. Much of the