An epitome of the investigations and recommendations of D. W. Brunton relative to the construction of a drainage tunnel for Cripple Creek is herewith presented, together with maps, reproduced by courtesy of the Rocky Mountain News.
Mr. Brunton's report was submitted to the Cripple Creek Mine Owners' Association on the 14th inst., at Colorado Springs, Colorado. Three projects were included in Mr. Brunton's report, and details of each were presented. These may be designated as the Cape Horn tunnel, Gatch Park tunnel and Window Rock tunnel.
The following table gives in concise form the main features of each project:
|Cape Horn||Gatch Park||Window Rock|
|Elevation of portal, feet||8,160||8,020||7,660|
|Depth below Cripple Creek Drainage Tunnel, feet||630||770||1,130|
|Distance to El Paso shaft, feet||12,840||14,550||17,200|
|Distance to the main water channel, feet||13,840||15,550||18,200|
|Distance from the portal to tunnel shaft, feet||8,840||10,570||12,690|
|Depth of tunnel shaft, feet||650||880||1,140|
|Length of time to complete tunnel, years||1.95||2.10||2.50|
|Depth gained, feet||605||740||1,090|
|Cost per vertical foot of depth drained||$628||$581||$468|
In considering the general course that the tunnel should take, Mr. Brunton says: "The vein and water courses of the Cripple Creek district have a general northerly and southerly direction. It follows that the most effective way to tap the greatest number of fissures in the least distance would be to run a tunnel in an easterly and westerly direction, and as near the center as possible, to afford the earliest relief to all portions."
In considering the respective merits of the three projects Mr. Brunton states that the Gatch Park portal would be chosen if the cost per linear foot drained were the same for each of the tunnels, for in striking a balance between the desirability of a deep level tunnel with its long life and certainty of drainage, and the necessities of many of the mines now working at or near water level, the Gatch Park project would more nearly fill the requirements than either of the others, but when the future of the entire camp is considered, Mr. Brunton's choice lies with the Window Rock tunnel, owing to the fact that an additional 350 feet of depth is secured at an additional cost of only $80,000, or $226 per additional vertical foot of ground drained.
"It will readily be seen that this is an advantage too great to be foregone and should lead unhesitatingly to the selection of the deep level tunnel."
The report further shows that the shortest routes to the productive area in the district are found in Cripple creek canon;
That while Wilson creek affords some excellent tunnel sites at 8,100 feet, the distance to the Gold Coin shaft would be 17,900 feet and to the igneous rock 20,500 feet.
The same results could be obtained by driving from a point in Cripple Creek canon, with a saving of 5,000 feet.
No formal decision was reached by the mine owners, but it is probable that the Window Rock project will be accepted, as this plan affords the deepest drainage with the lowest cost per vertical foot of depth drained. While the aggregate cost of the Window Rock tunnel will be considerably in excess of the cost of the others, it is considered the only practical plan, and the one that will best serve the future interests of the district.