Laserfiche WebLink
MAXWELL MINE <br /> TECHNICAL REVISION #1 <br /> The purpose of this revision is to remove two damaged 9-ft diameter <br /> culverts from the Purgatoire River under the access road to the Maxwell Mine <br /> and replace them with a 50-ft span Twin "T" bridge designed for a 100-year <br /> storm. <br /> CF&I desires to commence construction in late March or early April of this <br /> year and anticipates that the project will take three to four weeks to <br /> complete. April is the last month during which the Purgatoire River can be <br /> anticipated to be in low-flow conditions. Stream flow hydrographs of the River <br /> are included in this application as Exhibit B. Using the Madrid Hydrograph <br /> (downstream and thus larger flow) a flow of approximately 30 cubic feet per <br /> second can be anticipated during the month of April. <br /> Construction of this project will be as follows: <br /> 1) Temporary river crossing. A temporary river crossing will be <br /> constructed directly upstream (west) of the existing access road to provide <br /> access to the Mine during bridge construction and to aid in the construction of <br /> the bridge itself. This temporary road will be wide enough to accommodate one- <br /> way truck traffic and will not be over five feet high. At least seven 2-ft <br /> diameter culverts wil be placed on the river bed and anchored into place with <br /> old drill stem or other suitable material. River-run material (sand, coarse <br /> gravel, and cobble) will be taken from the "river-run borrow area" (Location <br /> Map - Exhibit A) and placed over the culverts. This material will be utilized <br /> over the river bed and it will not be necessary to ramp the river bank to <br /> construct this temporary crossing. After the bridge construction is complete, <br /> the river run material will be placed back into the "river-run borrow area" and <br /> 3 <br />