Discharges from shafts, slopes, and boreholes, which are vertical or steeply sloping excavations, are classified as below-drainage; these receive groundwater inputs with low dissolved O2, resulting in limited pyrite oxidation, dilution, and gradual improvement of CMD water quality.
Nonparametric Wilcoxon matched-pair signed rank tests between 1975 and 2012 samples indicate decreases in Fe and SO42− concentrations were highly significant (p < 0.05) and increases in pH were marginally significant (p < 0.1) for below-drainage discharges.
Water quality data collected in 2012 for 10 above- and 14 below-drainage coal mine discharges (CMDs), classified by mining or excavation method, in the anthracite region of Pennsylvania, USA, are compared with data for 1975, 1991, and 1999 to evaluate long-term (37 year) changes in pH, SO42−, and Fe concentrations related to geochemistry, hydrology, and natural attenuation processes.
Although a greater proportion of above-drainage discharges were net acidic in 2012 compared to below-drainage discharges, the increase in pH between 1975 and 2012 was greater for above- (median pH increase from 4.4 to 6.0) compared to below- (median pH increase from 5.6 to 6.1) drainage discharges.
If Climate change is leading to more intensive rainfall events, then previous above and below ground drainage systems will become expanded to cope with that change.
The findings indicated that the oxidation of soils has occurred at depths below the drainage pipes, with the median being at a depth of 1.6 m.
Worms do aerate compacted soil, and as they fold humus from the surface into the loam below, they improve drainage and deliver oxygen to roots.
There was no drainage below 1-m depth in the first month after spray application.
Field data confirmed that OSIRI simulates very reasonably well actual evapotranspiration and drainage below the sugarcane root zone.
The differential wood loss at these two depths appears to result from sustained anaerobic conditions below the tile drainage line at 120 cm depth.
