Historical mineral extraction, especially in the North Pennines at the headwaters of the South Tyne, East Allen and West Allen has caused disruption to the Tyne rivers. The natural flow of the rivers and tributaries in this area were interrupted and diverted for the mining activities of washing, dressing, smelting and hushing. The power of water was harnessed through waterwheels to drive drainage pumps and crushing devices.
An interesting legacy is the metal and mineral content left in the mines, which still make their way into the rivers. They pollute our rivers through water discharges from mine adits (horizontal mine entrances), and from the erosion and movement of spoil heap material through river systems. These materials contain lead, zinc and cadmium, which are highly toxic in freshwater environments.
These problems are not confined to the upper reaches of our rivers – riverbed material moves on high flows and is deposited far from its source. Sediments contaminated with heavy metals which originated in the uplands, and metal-rich sediments can be found throughout the Tyne system. In fact, rare metal-tolerant plants thrive on floodplains which are regularly inundated by metal-rich sediments and are protected. Calaminarian Grasslands are protected SSSI features in our landscape. One of the big conundrums for the future is how to manage the pollution from abandoned mines to acceptable levels while also preserving species and habitats protected under environmental legislation.
Actions to control pollutant sediments at source are a mix of innovative materials/equipment and traditional land, water and riverbank management. Many of the big sources are being tackled by the Environment Agency and the Coal Authority. Our approach is to pick up the smaller diffuse sites (eg. old spoil heaps which contribute metal-rich sediment to river systems during and following heavy rainfall), and our work in this area is growing. We and the North Pennines AONB Partnership are using our tried and tested green engineering methods (e.g. tree material, willow spiling, sediment traps and other forms of assisted natural recovery) at eroding sites which contribute metal rich sediments to our rivers.