Draft Environmental Impact Statement for Roca Honda Mine

Chapter 3. Affected Environment and Environmental Consequences
water due to WTP upsets, or discharge of treated water at uncontrolled locations because of
pipeline upsets. Each of the ponds has the capacity to store a 12-hour flow of 8,000 gpm, and the
ponds are plumbed so as to be interchangeable in function; that is, up to a maximum of 36 hours
of retention is possible for the design maximum WTP discharge, the WTP influent water, or any
combination of the two. During normal operation, a single discharge pond and the plant feed
surge pond would be on standby. Backup power would be installed.
Additional controls now in the plans include the following; see also discussion of “Surface Water
Impacts.”
• All locations where potentially toxic materials are to be stored would be lined or have a
concrete floor and drain to lined ponds which, in turn, discharge to the water treatment
plant.
• Storm water is routed such that it would not run onto areas of potential contamination
(e.g., it is diverted around stockpiles).
• Septic tank wastes, which were a problem at the Mt. Taylor mine, would be piped to the
water treatment plant, and would not be discharged through local leach fields.
• Fueling and vehicle maintenance would occur in designated areas or distant from
drainways, would be on level areas, and always supervised.
• Plans to prevent and control spills would be developed, including a storm water pollution
protection plan. Among other protocols, the plans would require training of personnel,
sampling of possible release, and availability of cleanup materials and equipment onsite.
Details on management of drilling fluids and cuttings are not complete, but are expected to
involve standard practices with use of short-term pits followed by restoration. Details on
discharge of treated wastewater to private land for use in a ranching enterprise are not available.
This use would probably result in substantial seepage of treated mine water to groundwater.
Provided the water has been treated to safe levels as planned, there would be no adverse impact to
groundwater quality.
An important component of any NMED approval would be requirements to monitor potential
discharges. The monitoring program as now proposed includes routine inspection of operating
and storage areas, instrumentation of key equipment (as an example, pressure sensors on
discharge pipelines), and monitoring wells. Monitoring wells are proposed for overall monitoring
of the process areas, including components that do not include leak detection systems per se—for
example, the lined retention ponds that drain the stockpiles.
In the area of the Section 16 facilities, RHR proposes four monitoring wells be completed in the
unsaturated zone, one each adjacent to the three retention ponds and one adjacent to the WTP
ponds.
In the unlikely event that significant contamination reached groundwater, it would be detected by
one of the three monitoring wells completed in the Gallup. Monitoring well locations are not yet
available for the Section 10 facilities, but would be identified in a future NMED permit (e.g.
renewal of the initial permit). This would be prior to any mining in that section.
An important monitoring provision would be a requirement for a post-mine radiological survey, a
measure recently identified by MMD (Clark, 2012). If such a survey also provided for evaluation
178 DEIS for Roca Honda Mine, Cibola National Forest