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The 25 year peak flow for the drainage basin of the River just upstream of Mosquito Gulch is <br />approximately 600 cfs. With the addition of Mosquito Gulch, the approximate peak flow for a 25 year <br />event is 900 cfs. <br />Since the mining operations and all associated activity will operate out of the River floodplain area and <br />will not discharge into it, it is not expected that the activity presented in this application will increase <br />any sediment, trace elements, dissolved solids or other water quality parameter in any way for the River. <br />All runoff on the active site will seep into the gravel piles located throughout the disturbed area. The <br />final plan incorporates the reclamation of the site, which will have better revegetation on all areas <br />disturbed. <br />Section 4. Surface Water Handling in the Permit Area <br />As described in the mine plan, the site will have no discharge due to the amount of depressions and <br />porous gravel present from past operations. The southern portion of the site will drain into the Settling <br />Pond, which is shown on Map C -2. This pond will have a surface area of 1500 square feet and will <br />handle the sluice tailings flow, as well as minor runoff in case of a large storm event. No discharge will <br />take place from this pond. Water from the pond will be recycled back to the sluice as needed for proper <br />sluice operation. <br />Once the mine is reclaimed, the pond will be regraded and reclaimed. <br />Section 5. Groundwater <br />The proposed operations are in recent gravels of the upper reaches of the Middle Fork of the South <br />Platte River. The area was glaciated in the last ice age and moraine deposits are also prevalent <br />throughout the drainage basin to Fairplay. The gravels are approximately 50 to 130 feet thick in the <br />permit area and are underlain by Pennslvanian sandstones and shales that have been turned upward at <br />steep angles. The gravels are interbedded with conglomerate, sand and clay beds located above the <br />bedrock. The alluvium immediately above the bedrock is most likely to have the highest concentration <br />of alluvial gold. Upstream from the permit area, the mountains of the Mosquito Range are schist, <br />gneiss and intrusive granite of Pre - Cambrian age. <br />Sullivan Aggregate Pit March 2015 H -3 <br />