Paper mill outfalls monitoring

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Over several years aquatic invertebrate surveys have been conducted to carry out the long-term monitoring of the outfalls from three paper mills, initially on behalf of Cresswell Associates, and later for Hyder and then Arcadis, which successively purchased the consultancy during the course of the project.

The mills included: Hollins Mill, which discharges to the River Darwen in Lancashire; Wansbrough Mill, at Watchet in Somerset, which discharges to the River Washford; and the Higher Kings Mill in Devon, which discharges to the River Culm. All three mills include treatment works to treat the waste water arising from the paper making process, to elevate it to a suitable standard that it can be safely discharged to the respective receiving rivers. Surveys of the aquatic invertebrate communities in the rivers upstream and downstream of the mills’ outfalls, coupled with RIVPACS analysis and WFD classification, enabled a qualitative assessment of the impact from each mill on the receiving waterbody.

Due to changing economic circumstances, both Hollins and Wansbrough mills closed in recent years, although the Higher Kings Mill remains in operation and monitoring there has continued from 2008 to the present. The results have shown a continuing legacy of highly diverse aquatic invertebrate assemblages both upstream and downstream of the outfall, providing the company with valuable long-term data to show they have continued to meet high standards of final effluent quality, with no discernible impact on the biota of the River Culm.