Laserfiche WebLink
Drilling Methods and Equipment: Exploration holes will be established with grubber-tiled tnrck- <br />mounted air/foam rotary drill. Drilling mud may be employed in the drilling medium. Previous <br />drilling activities in the immediate azea have not encountered water-bearing formations producing any <br />appreciable quantities of water from the strata overlying the coal seam of interest. Both the <br />Twentymile Sandstone and Wadge Overburden have been documented to contain water, however, <br />neither typically exhibits signiflcant flow at the surface. Drill hole depths projected for each site are <br />specified on 1999 NOI Table 1. After drilling the holes will be logged with a standard suite of <br />geophysical data logging instnunents. No holes will be developed as water wells. Exploration holes <br />will be sealed with cement grout installed with the drilling rig to within 3' of the surface. Drill cuttings <br />will be used to backfill the uppermost 3' of each hole. <br />In reference to the holes surface casing will be set 10' below bedrock to ensure drilling fluids are not <br />lost in the sur&cial soils. The surface casing will be grouted in place and then the hole will be <br />advanced as per normal methods. The sw-face casing at both sites will have a threaded surface collar <br />to allow for quick shut in of the hole in case significant flows aze encountered. <br />Holes PDH9901 and PDH9902 are relatively shallow (750' TD) as compared to other holes drilled at <br />the property and mainly will be advanced through 500 feet of marine shale that immediately overlies <br />the Wadge Overburden unit. Therefore, TCC does not anticipate encountering arty large volume of <br />water. The Wadge Overburden may produce a minor amount of water that can be contained within <br />the mud pits. <br />The coal will be cored and [he hole geophysically logged. Upon completion of the coring and logging <br />the hole will be tremie grouted through and twenty feet above the Wadge Overburden. From that <br />point up it will either be grouted or backfilled with cuttings to within ten feet of the surface. The <br />interval from ten feet to within three feet of the surface will be grouted and then the remai~~ng three <br />feet will be backfilled with soils. The surface casing will be cut off three feet below the sut-face or it <br />may be removed entirely from the site. The hole will be marked as discussed previously. <br />Seismic Line: Twentymile is planning to conduct a limited seismic investigation. This program will <br />use the classic approach of drilling holes, setting off charges, and placement of geophones and <br />instnrments for recording the data. With the advances in computer [ethnology, TCC is optimistic <br />better resolution of [he signal can be obtained and this will be used to define the fault. <br />The seismic will establish four lines approximately 14 miles in total length. The southernmost line <br />vends about S60W and extends 1,320 fr. from Nl/2 Sec 17, TSN, R86W to [he SWl/4 Sec 22, TSN, <br />R87W. The second line also extends 1,320 fr. on a similaz southwesterly trend It begins near [he <br />center of Sec 2, TSN, R86W and tem~inates in the SWl/4 Sec 7, TSN, R86W. The third line vends <br />westerly from neaz the center of Sec 2 [o the Wl/4 Sec 5, TSN R86W as shown on the 1999 Notice <br />of Intent seismic map (seismic99). The fourth seismic line has a basic east-west orientation and is <br />located in the N/2 N/2, Section 20 and the N/2 N/2 Section 21, both sections in TSN, R86W. Shot <br />holes will be established on 125 foot centers. The geophones may attend 1,320 feet past the ends of <br />the shot line. Dell holes will be approximately 20 to 22 feet deep and will have a nominal diameter of <br />4.5 inches. The cuttings from the drill holes will be mixed with bentonite chips to be used as <br />stemming over a 1 pound biodegradable charge that will be placed in the bottom of the hole. The <br />holes will be drilled with a small auger drill rig mounted on tires or tracks. There are no plans to <br />conswct any roads to aid in the drilling of the holes. The rig is sufficiently mobile to eliminate the <br />need for road building activities. All fence damage will be repaired immediately upon completion of <br />the seismic lines. Upon completion of the program the shot wires, marker stakes, survey flagging, lefr <br />over supplies, all trash, geophones and cable will be recovered. Based upon the limited depth of the <br />holes and the fact that the cuttings will be used to backfill the holes prior to shooting, no further <br />reclamation work is planned. <br />MONTGOMERY WATSON August 1999 <br />