Underground Mine CHIA Follow-up Study

EY 2001

Background

In 2000, OSM completed a study of the underground mine PHC/CHIA process.  The study found that the Probable Hydrologic Consequences (PHC) section of DEP’s permit application does not specifically address seasonal flow variations, as required by § 780.21 (f), and that DEP does not prepare a document that specifically details its Cumulative Hydrologic Impact Assessment (CHIA). OSM and DEP met several times throughout 2001 to discuss ways to reconcile the findings of the 2000 report.  DEP reconciled the seasonal flow issue by providing a document (Appendix A) that explains how seasonal flow is addressed in the PHC. OSM and DEP are currently working on the issue of CHIA documentation. OSM has provided DEP with five items for CHIA documentation:

1. Delineation of a cumulative impact area
2. Identification of current and anticipated operations with in the cumulative impact area.
3. Identification of water resources used in the CHIA
4. Establishment of a material damage threshold to protect the surface and ground water resources in the cumulative impact area.
5. A discussion of the assessment that leads to the finding at 86.37(a)(4).

OSM has offered technical support to DEP to resolve the issue of CHIA documentation.

Recommendations

OSM proposes to continue this study until the issue of CHIA documentation is resolved.  During this evaluation year, OSM and DEP have held discussions toward resolution of this issue. Additional, meetings are planned during the 2002 evaluation year.