2020-12-28_GENERAL DOCUMENTS - M1977300 (22)

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COLORADO LEGACY LAND FORMER$CHWARTZWALDER MINE 2.2 GEOTEXTILE, GEOMEMBRANE,AND GEOWEB LINING After the subgrade was approved, two layers of Mirafi 18ON non-woven geotextile were installed the entire length of the channel with a layer of Duraskrim N45BT2 geosynthetic liner sandwiched in between. The seams of the non-woven geotextile were melted together using a torch while the seams of the Duraskrim geosynthetic were welded using a DemTech Pro-Wedge VM-20 to form a water-tight and structural seam. Lastly, the channel was lined with Presto's 4-inch Geoweb. The Geoweb was installed per Presto's design presented in detail on sheet 7 of the design plans. The roadway crossing received Mirafi HP570 geotextile above the compacted subgrade and below the 6-inch Geoweb filled with 1.5-inch angular gravel. The design-specified geotextile liners were used throughout the design. 2.3 RIPRAP The design called for Dso=9-inch riprap in two different locations. One location was upstream of the ditch and seal wall while the other was at the bottom of the channel at the dissipation basin and riprap channel. The riprap was selected from the onsite borrow area and hauled to the project locations using a Caterpillar D250E rock truck.The riprap above the seal wall was placed 15 to 30 inches thick while the riprap in the dissipation basin and riprap channel was a placed at a minimum thickness of 14 inches using a Caterpillar 320 excavator and laborers.A visual inspection of gradation was performed for placed riprap with passing results. 2.4 CONCRETE A seal wall was constructed at the channel inlet near station 5+97 in accordance with the drawings and specifications.However,the depth of the seal wall increased due to the actual elevation of bedrock(see Section 3). Formwork and concrete were placed by the Construction Subcontractor and 4500 psi concrete was supplied by Burnco. In accordance with the Construction QA/QC Plan (Ensero, 2020), strength testing was completed each day structural concrete was poured. Slump,air content,and temperature tests were performed before placement with passing results.A set of five 4"x 8"cylinders were cast for compressive strength testing on both days structural concrete was poured. Each set met the specification of the 28-day curing age of 4,500 psi. The first set of cylinders were tested on day 35 with an average strength of 5,260 psi. The second set of cylinders were tested on day 31 with an average strength of 5,990 psi. The Geoweb lining in the channel was filled with 4,000 psi concrete supplied by Burnco. As this concrete is not structural but only serves as ballast within the Geoweb liner, laboratory testing was not ordered. Tickets collected during concrete placement are presented in Appendix D. Concrete testing sheets are presented in Appendix E. 2.5 RESEEDING The following seed was used to reclaim disturbed areas of the NWRP at the conclusion of construction activities: DECEMBER 2020 4 NWRP CHANNEL RECORD OF CONSTRUCTION