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The monuments currently in place for subsidence monitoring are 7/8-inch rebar <br />driven approximately 18 inches or to refusal into the ground. These monuments <br />have provided data of sufficient accuracy to determine the critical subsidence <br />parameters for the room-and-pillar panels at the Roadside South Mine. Abel (1982, <br />p. 6) states that, "Thin sandy soils, i.e. soils which have high permeabilities, which <br />rapidly drain away rainwater or snow melt and are not frost susceptible can <br />probably be successfully instrumented with steel bar monuments driven directly into <br />the ground, to refusal." Since the sandy soils of the relatively thick colluvium <br />overlying the strata above the mine meet this condition, the existing monuments <br />should be adequate for continued subsidence monitoring. <br />Approval to suspend monitoring at the Roadside Mines, unless mining operation <br />resume or unless the Division determines that monitoring should be resumed, was <br />received from the Division via a letter dated November 28, 2001. The approval has <br />been incorporated into the permit as Appendix 20-10. No subsidence features or <br />damages observed have been brought to Snowcap Coal Company's attention <br />subsequent to suspension of subsidence monitoring. <br />The Palisade pipelines were monitored on a regular basis during mining below the <br />areas defined previously to insure that subsidence effects, which could be <br />potentially damaging to the pipelines, would be detected early enough to prevent <br />such damage. <br />Subsidence monitoring over the Roadside North and South Mines primarily <br />consisted of a visual surface inspection in the spring and fall. The inspection <br />included areas over the next years' mining projections and over the past two years <br />of actual mining. The inspection included surface structures or features to be <br />undermined and evidence of subsidence. The features were documented and <br />photographed. Subsidence evidence was measured, recorded, mapped, and <br />photographed. The results of these semi-annual inspections were submitted <br /> <br />