PERMIT FILE - 11/7/2008, 10:46:17 AM-JWD

• Permit No: P2007069
• IBM Index Class Name: PERMIT FILE
• Doc Date: 10/29/2008
• Doc Name: Response to 5th Adequacy Questions
• From: RPM, Inc.
• To: DRMS
• Email Name: DB2
• Media Type: D
• Archive: No

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8 STEEL GRATED SHAFT CLOSURE
8.1 DESCRIPTION
This work shall consist of Installing steel grating over a shaft according to Standard Drawing Number 4,
including clearing and grubbing, excavation of loose material, trimming of shaft, and furnishing, securing, and
welding of steel grating and revegetation of disturbed areas in accordance with these specifications.
8.2 MATERIALS
Steel Grating shall conform to grating sizes specified in Table 10.1. Cross bars shall be resistance welded at
right angles to the bearing bars and spaced as specified in Table 8. 1. (type WXA bar as manufactured by
AMICO type 19-W-4-53, or equivalent).
Structural Steel shall conform to the requirements of ASTM A-36, all-purpose steel.
Rock Bolts shall be expansion-type with a minimum pullout strength of 2,000 pounds at an embedded depth of
4.5 inches. The rock bolts shall be Hird Heavy-Duty Expansion Anchor, Kwik Bolt or equivalent.
Anchor Bars shall be Number 6 (3!4') rebar in accordance with ASTM A 615, grade 60, anchored a minimum
depth of 8 inches (8") into competent rock with Moly Parabond epoxy capsule or equivalent, or with an
interference fit in drilled holes in solid rock.
Concrete shall have a minimum compressive strength of 3500 psi at 28 days.
Cement shall be Type 11 Portland cement, conforming to ASTM C 150, unless otherwise approved by the
PROJECT MANAGER.
Face and Coarse Aggregate shall confound to ASTM C 33.
Water shall be potable.
Admixtures shall conform to ASTM C 494; Calcium chloride will not be permitted.
Reinforcing Steel (rebar) shall be made of deformed new billet stock and shag conform to ASTM A 615, Grade
60. All reinforcing steel shag be free from heavy rust, scale or other coatings that will destroy or reduce the
bond.
8.3 EXECUTION
8.3.1. Grating spanning shaft openings
Fabrication
The grating shall be welded to a 2" x 2' x Y.' angle iron framework which will be securely anchored to the
perimeter of the opening. On sites where bedrock is near the ground surface the framework will be anchored
using six inch (61 minimum rock bolts or anchor bars inserted into a hole drilled eight inch (8') deep minimum,
to accommodate the bolt or bar with a non-shrink grout, such as Moly Parabond, Pour Rock or Kvrik Crete_
Rock bolts or anchor bars will be twelve inches (12*) center to center with a minimum two-feet (2') setback
from the edge of the opening. The bolts or bars shall then be welded to the framework. Ali welds shall be in
accordance with the American Welding Society AWS 01-1.
Installation
Unless otherwise noted in the special conditions, all Steel Grated Shaft Closures must span the mine opening.
Colorado Division of Minerals and Geology
2004
GENERAL BID SPECIFICATIONS
Page 39