Laserfiche WebLink
APPENDIX 2.05.3(4) -7 <br />NHN -001 EAST AND WEST DITCH AS -BUILT <br />11.0 Introduction <br />and NHN -001 is fed by two collection ditches, NHN -001 West and NHN -001 East, running along the west and <br />ast sides of the south drainage basin of the New Horizon Mine. These ditches were designed as part of the <br />riginal permit application (please see Appendix 2.05.3(4) -1), and were constructed in January 2013. This <br />appendix includes the construction certification documentation for both ditches and demonstrates that both <br />ditches as- built, are sufficient to safely pass the flows from a 10 -yr 24 -hr event. Table 2.05.3(4x7 -1 provides <br />he as -built conditions of each segment by station. The as -built condition of both ditches, including cross- <br />sections and station information are presented on Map 2.05.3(4) -7. <br />This as -built documentation supersedes ditch design information presented in Appendix 2.05.3(4) -1 for the <br />egments shown on Table 2.05.3(4) -7 -1. For any future extensions of the NHN 001 East and West Ditches <br />outside of the stations listed in Table 2.05.3(4) -7 -1, they will be constructed to the specifications outlined in <br />Appendix 2.05.3(4) -1. <br />During construction of the NHN -001 East and West Ditches a rip -rap substitute was installed called Geoweb <br />ellular Confinement Systems GW30V ( Geoweb). Geoweb is a honeycomb of plastic material that is staked to <br />he channel bottom, and then filled with the appropriate sized riprap to substitute for a rock lined channel. The <br />eoweb material holds the selected rip -rap in place, and limits velocities in the same manner as a rock -lined <br />hannel. SEDCAD outputs presented in section 2.3 for the NHN -001 East Ditch indicate a required D50 of 1.5 <br />ches to 3.0 inches (dependent on the segment, please see Table 2.05.3(4x7 -1) for velocities ranging from <br />4.17 fps to 5.35 fps. SEDCAD outputs presented in section 2.4 for the NHN -001 West Ditch indicate a <br />required D50 of 1.5 and 3.0 inch for both rip -rap lined segments of the ditch (see Table 2.05.3(4) -7 -1). <br />Velocities for the NHN -001 West Ditch rip -rap lined segments are 4.6 fps and 5.5 fps respectively. The <br />hydraulic analysis data sheet provided by the manufacturer in section 2.5 demonstrates the velocity limits for <br />he Geoweb for a select set of riprap sizes. The range of velocity for GW30V with similar sized rock is 11.69 to <br />2.01 fps. The highest velocity in the both ditches is 5.5 fps, therefore, GW30V was selected and installed as a <br />substitute for 1.5 to 3.0 inch rip -rap material. The installation details for the Geoweb is presented in Figure <br />2.05.3(4)-7-1. <br />APPENDIX 2.05.3(4) -7 PAGE - 2 - AUGUST 2013 (TR 04) <br />