Laserfiche WebLink
Attachment 3 -Calculation of Seepage from Boulder Feeder Canal <br />Page 1 of 1 <br />Model Assum tp IOnS <br />Seepage from the Boulder Feeder Canal was estimated using Darcy's Law. Parameters used to <br />estimate the amount of seepage from the canal included: <br />• The estimated length of the Boulder Feeder Canal that could potentially provided seepage <br />to C-Pit is about 2,400 feet; the average wetted canal width and depth of the water was <br />estimated at 16 feet and 3 feet, respectively <br />• The period of operation of the canal was estimated at 180 days (April 15"' -October 15`s) <br />• The hydraulic conductivity of the underlying weathered and unweathered shales was <br />estimated to range between 1 x 106 and 1 x 10.5 centimeters per second (cm/s) based on <br />pressurized packer tests at Dowe Flats. The surface of the channel has also been sprayed <br />with cement in the past to minimize leakage. <br />• The vertical thickness of the shales beneath the bottom of the Boulder Feeder Canal and <br />the potential seepage face along the west end of C-Pit was estimated at 50 feet. <br />Seepage Calculations Using Darcy's Law <br />Dazcy's Equation Q=K*[(H+d)/d]*A <br />Where <br />Q =seepage rate (ft3/d) <br />K =hydraulic conductivity (ft/d) <br />H =depth of water in canal (ft) <br />D =thickness of shales underlying canal (ft) <br />A =wetted area of canal (ft~) <br />Lower Range Upper Rance <br />K (cm/s) 1.00E-06 1.00E-05 <br />K (ft/d) 2.83E-03 2.83E-02 <br />H (ft) 3 3 <br />d (ft) 50 50 <br />A (ftZ) 38,400 38,400 <br />Q (ft3/d) 115 1,154 <br />Q (gal/d) 863 8,631 <br />Q (gpm per day) 0.6 6.0 <br />Days of Operation 180 180 <br />Annual Q (ft3) 20,769 207,687 <br />Annual Q (gal) 155,350 1,553,495 <br />