Laserfiche WebLink
total of the post-mining LS factors of 184.66. This would indicate that site-wide, post- <br />mining slope and grades are similar to the premining conditions. <br />The Division does not agree with the C factors used for either the premining or the post- <br />mining conditions. Colowyo ignores the Phase II vegetation data when selecting <br />premining C factors on a parcel by parcel basis. Instead, they use somewhat arbitrary <br />information based on the premining vegetation community. It is not valid to compare a <br />reclamation parcel sampled for total cover in 2006-2009 to premining information <br />collected decades before the current Phase II sampling. Colowyo should select the C <br />factor on a parcel by parcel basis using the premining vegetation community (as shown <br />on Maps 3 and 4) to develop a weighted average of Mountain Shrub versus Sagebrush <br />areas, then use the 2006-2009 reference area vegetation sampling data, specifically <br />vegetation and litter cover, to calculate a C factor. Using the reference area data fairly <br />compares the seasonal climatic conditions and growth of the reference area with the <br />seasonal growth of the actual reclaimed area. Both were subjected to approximately the <br />same climatic conditions as since the comparison is an estimate of the "annual" amount <br />of soil loss, it is only fair to compare using data accurately reflecting the annual <br />variations. It is noted that each of the Colowyo's four years of sampling data included <br />both reference area sampling and reclaimed area sampling. <br />Colowyo also used a uniform, site-wide C factor of .010 for the post-mining condition. <br />Again, this is not appropriate, as the C factor can be readily and accurately estimated <br />using the Phase II vegetation sampling data for the individual parcels. The Division <br />notes that Colowyo used specific information for each parcel for the K factor and the LS <br />factor. <br />The Division does not concur with the selection and use of the post-mining P factors used <br />in the calculation. Colowyo has fixed the premining factor, which is acceptable. <br />However, no adjustment of the post-mining P factor is warranted. The practice of <br />contour plowing and cultivation due to drill seeding is marginal at best. In addition, since <br />the calculation is an annual estimate, it is not appropriate to credit this roughening <br />component to lands that receive no management practice after the initial seeding. The <br />post-mining P factor should be equal to the premining factor unless the Colowyo can <br />document that management practices were used on a recurrent basis and/or any <br />management practice employed at the time of seeding remains functional at the time of <br />Phase II sampling. <br />Colowyo should revise the RUSLE parameter input based on the above comments and re- <br />submit Table 4. C factor information, based on the 2006-2009 revegetation monitoring <br />data, is presented below for the reclamation and reference areas.