Laserfiche WebLink
© Mr. John Morron~ <br />Apri! 3, 2007 <br />Page 4 <br />• Copies of the stipulations. <br />• The typical drillhole abandonment figure. <br />• A ]0/87 USGS memo addressing the status of the drillholes at that time. <br />• An a-mail from I<4atthew Janowiak (BLM Hydrologist) addressing hydrologic <br />concerns relative to the boreholes. <br />In summary, a concern was noted that the exploration drillholes may have been converted to wells <br />without BLM concurrence or approval and may not have been properly completed. Improper <br />completion could result in voids in the annular space between the well casing and borehole making <br />it difficult or impossible to properly seal the borehole without either perforating the casing or <br />drilling it out. A discussion of the borehole closure objectives and requirements followed, with <br />consideration of the following facts and issues: <br />• Kerr's original mining plans that included mining through most of the boreholes <br />• Protection of ground water <br />• The lack of ground water occurrence on the west limb of the syncline <br />• Long-term protection of the coal seam as a resource <br />• Potential impacts of open or vnproperly sealed boreholes on CBM development <br />• Adequacy of surface plugging to meet closure objectives <br />• Different closure methods for dry and wet boreholes <br />• The practical difficulties of trying to remove casing or overdtill the boreholes to dtill- <br />out the casing in small diameter boreholes (most aze 2" PVC casing) in steeply <br />dipping strata (significant potential For the drill bit to wander out of the hole) <br />• Regulatory requirements <br />• T imitations relative to the lease stipulations for drillhole closure (non-speufic, no <br />aquifers per se, does not address ho~v to handle casing, reflects flat-lying coal seams <br />vs. the steeply dipping beds in this situation) <br />• Specific closure requirements based on individual borehole conditions (i.e.: casing <br />diameter, depth, completion conditions, type of casing (slotted vs. non-slotted), etc.) <br />Based on these discussions, it was agreed that additional information is needed before a final <br />decision on closure methods can be reached. MWH will review the documentation for individual <br />boreholes to determine which and how man}' boreholes may pose specific closure problems. Both <br />MWH and the BLM will teseazch methods that can be used to determine whether or not voids <br />