Laserfiche WebLink
vJ RE�� <br /> cr 3°,?018 <br /> Greg Lewicki And Associates, PLL0h4 <br /> 3375 W.Powers Circle Phone: (720)842-5321 Fax(303)346-6934 <br /> Littleton,CO 80123 E-mail:info@lewicki.biz <br /> October 25, 2018 <br /> Stephanie Mitchell <br /> Colorado Division of Reclamation, Mining, and Safety <br /> 1313 Sherman St, Room 215 <br /> Denver, CO 80203 <br /> RE: Grey Rock Aggregate Company,Moonscape Pit M-1997-027,Technical Revision <br /> No. 2 (TR-02)Adequacy Response <br /> Stephanie: <br /> Please allow the following and attached information to satisfy the adequacy requirements for <br /> TR-2 of the Moonscape Pit. <br /> 1. Signed letter from local contractors stating they will accept imported glass for use as road <br /> base in their construction projects. See `Letters from Contractors—glass import <br /> 181024.pdf <br /> 2. Imported glass will be used expressly for road base and will exclude chip seal and asphalt <br /> at this time. Any change regarding the utilization of glass will be submitted in a <br /> subsequent technical revision. <br /> 3. Class 7 base aggregate total percent passing thresholds fail when lass sizes are smaller <br /> P p g g <br /> than 75 micrometers/200 mesh size. See the included Table 3138-2 from MnDOT <br /> specifications guidelines, 2005. NIOSH and OSHA glass fiber exposure limits have a <br /> minimum size threshold of<3.5 µm in diameter and> 10 µm in length, see the included <br /> NIOSH 7400 methods sheet. Therefore, because MnDOT Class 7 thresholds are more <br /> restrictive and limit glass sizing to 75 µm as the smallest size fraction,problematic <br /> airborne fibrous glass is not anticipated to be a problem. Furthermore, as glass will be <br /> crushed on site to an average size range of 2—3/8 inch in size, it is unlikely that crushing <br /> will create a significant fraction of fibrous glass particles. However, crushing will occur <br /> wet and screens will capture and minimize any potential fibrous glass fractions. All <br /> necessary permits will be secured for crushing and screening equipment. <br />