Lausanne Tunnel
A meet up event on September 10th was coordinated by Tom Torres to visit an Abandoned Mine Drainage (AMD) site and Matt MacConnell (standing at right end of photo) led the entourage of 27 through the site. The visit was a working trip where water quality and flow measurements were made.
The group split into groups and some measured ferrous iron concentration at the inlet and compared this to the ferrous iron at outlet (4.8 ppm --> 3.4 ppm) to determine how much was being removed. Another group used the rectangular weir to calculate flow through the wetland (1625 gal/min.) A third group used the water quality monitor to check dissolved oxygen levels across the iron settling wetland (40% at inlet, 60% at midpoint and 80% at outflow.) A fourth group downloaded flow data from the solar powered data logger to get flow profile information over the last 12 months.
The wetland works by oxidizing soluble ferrous iron to insoluble ferric iron so increasing CO2 saturation levels in the water is key, as it is maintaining design flow (~1800 fpm)
