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NAXINUN GRADES FOR HAUL ROADS Overall Pitch Pernissable Length Road Class Grade i Grade ~% of Pitch Grade Llass 1 ~ 10 15 300 (Maximum . length within 100 feet) Class 2 10 15 300 (length) III. TRANSVERSE GEOMETRY the transverse geometry, the cross section of the road are of great importance especially in ensuring good drainage of the road end stable constroctton. The Regulations specify the width of haul roads re- quired. Skelly and Loy's report gives the following des lgn guide for vehicles up to 100,000 pounds gvw. The width for 1-lane (23 ft.) and 2-lane (40 ft.) haul roads on curves are shown in Table 2. TABLE 2 ~ RECOMMENDED NIDTHS FOR HAUL ROADS Curve Radius One-Lane Two-Lane (Ft.*) Haul Nay Haul May 25 27 48 50 25 44 100 24 42 200 23 41 'On the inner edge of the pavement. If the area upstream of the haul road is also disturbed, all runoff from the road must be passed through a.sedi- nent basin [816.42]. Therefore it is clearly best to try to concentrate road orainage at a few selected points. This will mean the use of roadside ditches, usually located on the upslope side of the road, with a reverse fall on the whole roadbed so that all drainage Fl ows to the ditch (Fig. 2). This will mean a culvert under the road at each sag in the vertical profile. In steep terrain where most haul roads will be on cut end fill, a downslope ditch would have to be located on fill (Fig. 3) and would be liable to washout unless lined. The reverse fall also prevents overland flow from upslope areas flowing onto the road. Cross-slope to give rapid drainage of surface water should be h-~."/ ft (10 ). However in flatter terrain such an arrange- ment or a cambered road with a ditch on both sides is possible when road is in total cut .d atsyev,°~ ~ ~ y <cvsRfl ra'. q~pee k./ roF hr r...1e. / ~~j7 ' Y~ ~911H•xYilAis. rts.,raA ~~ F ~-' ~l~hstoYd ~~ Difch baaiad pn qfk. rwf:•IosrdlC Lurves on haul roads should normally be superelevated (banked) for greater safe-operating speeds. Super- elevations will normally be banked Into the slope of the land at crests and away at sags which allows most drainage to be handled in upslope df tches as suggested above. The Regulations do not specify superelevations, but Skelly and Loy's report gives criteria for calcula- ting superelevations necessary on high-speed haul roads. The Regulations specify maximum slopes for cuttings and embankments on haul roads for Class I and II roads. These are shown in Tables 3 and 4. TABLE 3 NA%IMUM CUT SLOPES FOR NAUL ROADS Road Class Unconsol7dated Material Rock !gl Class I 1v:1.Sh iv:0.25h Class II 1v:1.5h 1v:0.25h Class III no standards specified MAXIHUM SLOPES FOR EMBANKMENTS IN HAUL ROADS Road Class Unconsolidated Fill Rock Class I lv:2h 1v:1.35h Llass II 1v:1.5h 1v:1.35h Sloss III no standards specified Topsoiling and temporary erosion control measures are required for Class I and I1 roads in the performance standards for slopes of 1v:1.5h or flatter (i.e. those s topes not 1n rock or constructed of rock fill). IY. DRAINAGE [816.153, 816.163 AND 816.173] On Class I roads the drainage system must be designed fora 10-yr, 24-hr precipitation eveh t. Sedimentation control for all classes of roads must comply wfth Sections 816.42 and 816.45 requiring that ail runoff from "disturbed areas" be passed through sedimentation ponds; however, Section 816.42 (a)(4) notes that "dis- turbed areas" do not include those areas in which only roads are installed if the area upstream of the road is not "otherwise disturbed." Natural drainage channels may not be altered without the approval of the RA and may not be altered at all in the case of Class II[ roads. Drainage structures are. required for all stream crossings. 4:1 Ditches are required for Class I road (on both sides of a throughcut and on the inside shoulder of a cut-and-fill section). Ditches are not necessar- ily required for Class fI roads where ditches, • GROUP MOBILIZATION AND MINING OPERATIONS HAND BOOK ~ • FOR MEASURES HAUL ROADS SMALL MINE OPERATORS 2 47