Laserfiche WebLink
Page 8 <br />appeared far more consistent with the prevalence of warm season grasses in the dataset of the <br />application. <br /> <br />Since vegetative production on this site has been shown to be closely connected to precipitation, the <br />Division suspected that 2023-2024 was a dry year, resulting in minimal new growth. This was confirmed <br />by a CEC representative, who provided the following precipitation data. It can be seen on the graph that <br />precipitation was well below average during the late spring and summer of 2024 (May – July). <br /> <br /> <br />These precipitation trends supported the Division’s observations and explained why there was little new <br />growth this year. The new growth observed around the previous years stands and plants growing seed <br />heads, especially in Area 31, suggest that the revegetated area is self-sustaining. The Division found that <br />the data collected in 2021 and 2022 accurately reflect site conditions, based on observations during the <br />inspection. <br />CEC used the Revised Universal Soil Loss Equation (RUSLE) to demonstrate acceptable soil loss on the <br />reclaimed lands. The Division has previously approved CEC’s use of this model to demonstrate <br />acceptable sediment solid demonstration. <br /> <br />The key factor in comparing the reclaimed area to the nearby undisturbed area is the Cover Factor, C. <br />The C factor in RUSLE accounts for the effect of plant and litter cover on the ground surface in reducing <br />erosion. For the undisturbed areas, the cover factor used in this analysis (0.036 for a sage sand <br />community) is the same as approved by the Division in previous RUSLE analyses for this site. The C <br />factor for the reclaimed area was determined using vegetation monitoring data. The C value used in the <br />application is 0.013, which is in agreement with a check by the Division using Table 5.A.3 in Applied <br />Hydrology and Sedimentology for Disturbed Areas (Barfield, Warner and Haan, 1981). <br /> <br />CEC’s calculations determined the undisturbed area would contribute 0.079 tons/acre/year of sediment. <br />The reclaimed parcels were calculated to potentially contribute 0.049 tons/acre/year of sediment. The <br />Division considers the demonstration acceptable, and it shows that the reclaimed areas are projected to <br />contribute less sediment than the undisturbed condition. The results of CEC’s calculations are found in <br />Table 3 in the Sedimentology Demonstration in the SL-12 application. <br /> <br />Two sediment ponds have been designated as permanent at the Keenesburg Strip Mine. These ponds <br />were both constructed below grade. Inspections by the Division and CEC have shown for many years