Mousewater Mine Water Treatment Scheme

Site History - The scheme at Forth, South Lanarkshire is part of the Coal Authority´s minewater remediation programme. The scheme has been designed to treat the ochreous minewater which was discharging from a mine adit across the site and into the Mousewater.

Water Chemistry - The Iron content in the water at the adit is 25mg/l, this is reduced to below 10mg/l before the water enters the reedbeds. The reedbeds at Mousewater will reduce the iron content in the minewater from 10mg/l to 1mg/l once the scheme has fully matured.

Mousewater was Class C for Iron in 2004 in 2005 the results have improved and the mean value has now dropped to below 2mg/l.

Site Design - The scheme is entirely passive using only gravity to move the minewater around the site. An entirely passive system is the Authority´s optimum solution as there are no long term maintenance or energy costs. The primary settlement lagoon at Mousewater has an innovative design. As there is the part of the treatment and system where a high proportion of the Iron is removed from the water there is a need for sufficient access and flexibility when emptying the ponds. The lagoon has precast concrete dividing wall, this cuts the settlement pond into two halves whilst appearing as a single pond, this allows either half of the pond to be drained down for removal of settled ochre whilst treatment continues in other half. After primary treatment in the lagoons the minewater passes via a channel and into the secondary treatment phase, this takes the form of two reedbeds which together have a surface area of 8400 metre squared. The partially treated minewater passes through the two reedbeds undergoing further treatment and final polishing before the remediated water is passed into the Mousewater. Reeds are used because they have a high iron resistance and thrive in waterlogged conditions, surviving in up to 12 inches of water. Reeds also have extensive root structures and its these structures that are an integral part of the filtration process within a reedbed remediation system.