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JUL-31-98 FRI 06 05 RM DMG~RANGO FIELD OFFICE FAH NO. 9747+5104 P, 03 :, '~ (Page 2) MIL7E ID !1 OR PROSPECTING ID # M-'7i-21s INSPECTION DATE 6-7.-9$_ INSPECTOR'S INITIALS SCG_ RVAT This was a partial inspection conducted to evaluate the area of the 9360 portal seal second monolithic concrete block, prior to pouring the concrete. Pouring of the concrete was also observed. The area inside the concrete Eorms was inspected approximately 2 hours prior to the concrete injection pumping. Most of the lagging was still in place on the ribs except for in the places where a grout injection pipe was placed. All lagging had been removed £rem a section of the back between two timber sets. The caved area above this section was approximately six feet above the top of the sets. Spreaders and timbers at the base of the sets, running parallel to the edit were all sl-ill in place. This condition is of concern as it may provide a continuous flow path through the concrete block that water could conceivably pass through as the timber degrades. During the 4.8-96 inspection, the Division specified that Homestake would need to remove all lagging and timbers from a section of the edit where the first section of the plug was to be constructed, so there would be a full circumference, concrete to earth contact, with no wood passing through it that may provide a flow pooh for water to channel through 'the seal. ~ Homestake was directed to photographically document this wood free zone and submit that documentation to the Division. This documentation has not been submitted as of this inspection. Therefore, the Division has no evidence that there is a full thickness wood free zone ir1 the first section of the portal seal. Homestake indicated, duzing the Division's 5-13-55 inspection, that all the lagging and timber was not removed from the area between two timber sets which was LO be~cut out to disrupt any potential continuous flow paths through tho seal. Homestake indicated that a section OP lagging and other timber, around the snore circumference of the edit, would be cut out of the area for the second conczete block of the seal, and that the second block would be the area wheze the best seal would be provided because there they would get a full thickness concrete to earth seal, free of any wood. Inspection of the area of the second concrete block, two hours prior to pumping the concrete revealed that lagging in the back had been removed between two timber sets and caviny had occurred to approximately six feet above the sets. Grout, from the injection around the first plug section, was visible in voids and cracks where the back had caved away. Hardly any lagging had been removed from the ribs except where grout injection pipes had been placed to pump grout around the second section of concrete plug. it appeared that no timbers from the floor, oriented either parallel or perpendicular to the edit, had been removed. A few one inch holes had been drilled through each lagging board LO aid yrout penetration. Homestake was advised of the Division's concern about the amount of wood remaining in this ozone. Homestake indicated that regard for the safety of the miners was the yeaso:l for not removing all wood between these sets. Steve Philip6 of Philips Mining, Geote cktr[ical ~ Grouting, Inc., indicated, contrary to earlier statements from Homestake personnel, that all wood was removed from a zone between two timber seta in the first section of the plug. Homost aloe Personnel indicated the[ p}rotographic documentation o£ that area was taken prior eo removal of tall the lagging, so it would not verify Mr. Philips statement. Therefore, Homestake is directed to submit an as-built report for the adiL seal construction, upon completion of Che structure. Ocher than the lack of timber removal, the area of the second plug section was clean, loose debris had been removed and the face o£ the first plug section had been scoured to provide