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<br />rui. rualASl. snvr,ce <br />Page 4 <br />January 7, 1981 <br />5) Bob Liddle's corm~nts fran prom of Decemter 18, 1980. <br />6) The berms will be 2.5' in height and will have <br />side slopes of 2h:1V. This will be sufficient to ensure that <br />the two types of drainage are not intermingled. The tem- <br />porary diversion ditch will be extended to the north to <br />ensure that undisturbed drainage does not flow into pond <br />22-P1. <br />8) Refer to Darry's letter of January 5, 1981 to <br />Jim Kent. <br />9) TBM is in the practice of retrovinq topsoil from an <br />area prior to disturbance and will not change from this practice. <br />Therefore, topsoil will be salvaged from pond areas prior to <br />disturbance. <br />10) A collection ditch does route water from the eastern <br />side of the coal stockpile into pond 15-P1. The actual drainage <br />area for this ditch is approximately 1 acre. An Arizona <br />crossing is used at the point where the road intercepts the <br />ditch. <br />Design <br />Q = 2.14 cfs <br />Slope = 2.3 percent <br />P = 2.67 2.14 <br />38.39 (.15) <br />_ .37 <br />Add .5' freeboard <br />_ .87 feet <br />2h:lV side slopes <br />Tlie ditch as it is constructed now is approximately <br />18" deep with 2h:lV side slopes. 'Ifiis ditch has functioned <br />~ effectively~iri collecting and transmitting water to pond 15-P1. <br />12) Cl~lvert C-12 is comprised of two five foot culverts and <br />as of this time has passed all the drainage without any problems. <br />This historical performance should be evidence that the culverts <br />will function l7roperly as the runoff and thunderstorms received <br />in the area last year were above the normal. It would to to <br />