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<br />An acceptable procedure is the use of a design nomograph <br />such as provided in Handbook of Steel Drainage and Highways Con- <br />structon Products, page 161. This type of nomograph shows cul- <br />vert capacity Q as a function of culvert diameter D and the head- <br />water depth to diameter ratio, Hw/D. Using this method, the 30" <br />culvert carrying North Fork flow under the haul road between pits <br />1 and 2, and the two 18" culverts for Ditch D were determined to <br />be undersized. The applicant should redesign these culverts to <br />account for entrance losses. Therefore, the following stipula- <br />tion is proposed. <br />The applicant must increase the size of the 30" and <br />C J~ ~ two 18" culverts to 42" and 24" respectively, or jus- <br />tify the smaller culverts with complete design calcu- <br />A" <br />lotions and drawings using an acceptable engineering <br />~`~"a ~~ methodology. The extent of ponding and potential for <br />~~~ overtopping the road must be addressed in particular. <br />,~~j' <br />~ Monitoring Program <br />The proposed monitoring locations, frequency, and parameters <br />appear adequate to determine surface water impacts to the North <br />Forlk of Bolto(n/D/raw1. ~c5 J~x~~ 1-(1e c~,s ~~esc°I~Ee~ is irisv~~~c~E~a~f- E-ef <br />~~'Ftaw~~l~; t1Q iFtf c}5 pr~~~a i}t~1W ~I ~//Yie ~,ha-~n E.tC.I~ <br />Hydrologic) Balance \J <br />The proposed reclamation plan will restore all or parts of <br />three ephemeral drainages tributary to North Fork of Bolton Draw <br />or to Bolton Draw directly (Pit 1). The reconstructed stream <br />channels as proposed will approximate their pre-mining configura- <br />tion except that slopes in the Pit 1 area will be slightly <br />steeper and steep slopes in the Pit 2 area will slightly longer. <br />After an initial period of adjustment, impacts to the hydrologic <br />balance, for surface water quality and quantity, are expected to <br />be slight. <br />-76- <br />