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I I I I I I I I I I I I I I I I I : I I I I'\r, David Burke rJo'lember 15, 1979 Page Three Prior to mining days the hydrologic setting of this area was probably conducive to both the development of wells and the disposal of wastes through septic tanks and leach fields; however, because of the extensive tunneling and the numerous tailings deposits scattered throughout the area, this hydrologic setting has been distrubed, Water from aquifers may still be available, although it may be difficult to find an area in which to drill that does not intercept a tunnel or shaft. The extensiye faulting in the area will provide conduits for ground water to travel along and adjacent fracture porosity should also provide signi- ficant amounts of ground water. In addition, ground water may be expected from the alluvial deposits within Evans Gulch, Waste disposal may be a problem for two I'easons, First of all the many tail ings piles, if unduly saturated with waste disposal water, could become mobile and cause problems through sliding. Secondly, the numerous shafts and tunnels in the area may provide conduits for liquid waste to travel along and potentially pollute the ground water system in the area, Thus, I feel that this problem is one that requires further close scrutiny, perhaps by the County Sanitation Engineer or some other soil scientist trained in waste disposal problems. In summation, it appears that the northwest portion of this tract is most am- mendable to development because of the relative rarity of both faulting and mining actIvIty. The unconsolIdated surfIcIal deposits, probably glacIal out- wash material, will provide good foundation supportive material and will also be permeable enough to provide suitable waste disposal systems, if the contamina- tion possibIlIty previously mentioned can be mitigated. The landslide and rockfall areas should be totally avoided for development, as well as the one Jvalanche path noted in the southeast corner of the tract. Avalanche tracts for t,his report are labeled with an "A" or the word "Avalanche" and faults are labeled with an "F," Lower areas adjacent to the floodplain of Evans Gultch may also be suitable for development but will require site specific examination for each individual unit, It is my opinion that density for this particular tract, in view of the significant problems effecting it, should be fairly low. SOUTHEASTERNMOST LAND USE AREA - Iowa Gulch - This area underwent much less mining activity with that being concenrated in the northwest corner, This is probably because, although upper Paleozoic units such as the Minturn Formation and Belden Shale probably crop out in this area, the Laramide intrusives do not crop out as extensively and therefore mineralization was not as high as in the previously discussed area, Because of the relative lack of minIng activity in this tract, only the north- west corner has a minor subsidence potential. There are hazards however, notably the fairly large avalanche chute coming down from the northeast, and two smaller avalanche chutes coming into the area from the south; the faults in the area which should be avoided although they should not be a problem except in the event of earthquakes in the Colorado region; and the possibility of flash flooding in some of the gulleys of the tract especially were shown on the accompanying map, In thIs tract water well developn1ent should not be significantly affected by previous mining as there is not a high likelyhood of intercepting tunnels except in the northwest corner of the t,l'act, In addition, the waste disposal problem is at a minimum, because ground watel' percolating through the permable soils of A - 10