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Stioulatiot~ Ido. 16 <br />• WITHIN 6 MONTHS OF PERMIT APPROVAL, THE PERMITTEE MUST <br />INSTALL A 21 INCH OR LARGER CULVERT AT STATION 12+50 OF <br />THE NORTHERN N0. 1 HAUL ROAD. IPA ADDITION, THE PERMITTEE <br />MUST SUBMIT A PLAID FOR DIVISION APPROVAL TO BRING THE <br />EIGHT 36 INCH CULVERTS Ai STATION 31+50 OF THE NORTHERN <br />N0. 1 HAUL ROAD INTO COMPLIANCE WITH THE SIZING RERUIRE- <br />MEIdTS OF RULE 4.03.1(4)(e)(i). THE PLAN MUST BE IMPLE- <br />MEi4TED WITHIN 30 DAYS OF DIVISION APPROVAL. <br />Northern Coal's Answer: <br />A 21 inch or larger culvert will be installed in the <br />Northern No. 1 Haul Road as requested. <br />Calculations performed by a Registered Engineer (copy <br />attached) show that the eight 36 inch culverts are capable <br />of passing a 10 year 24 hour. event. Should an event <br />greater than this occur, the excess flow would be diverted <br />along the Haul Road in a ditch, through culverts and into <br />the natural drainage of Curtis Creek. Since the haul road <br />is 1.5 feet higher than the top of the culverts in question, <br />there will be no chance of the water topping the road in <br />the case of a 20 year 24 hour event. By allowing the excess <br />• water to travel in the ditch along the haul road, erosional <br />damage will be kept to a minimum on surrounding areas. <br />• <br />_46 A <br />°7/ <br />