Retention of suspended solids and sediment bound nutrients from peat harvesting sites with peak runoff control, constructed floodplains and sedimentation ponds

Increased requirements for drainage water treatment has lead to the development of new methods for removing suspended solids and nutrients from peat mine drainage waters. Peak runoff control, constructed floodplains and sedimentation ponds were studied in the field at the Pohjansuo peat mine in Central Finland. Sediment and nutrient concentrations were observed during non-frost periods of 1995 and 1996 and during spring thaw in 1996. The results show that peak runoff control in particular is able to remove suspended sediment almost completely and particle-bound nutrients partially. The new method fulfils the requirement for a 65% reduction in suspended solids set by the authorities without affecting the peat harvest. The low cost of these new methods makes them available for most Finnish peat mines.