Allt a'Mharcaidhl River Restoration

Tender description

Tender For The Supply Of River Restoration Project On The Allt A’mharcaidh Burn Lot 1: The Allt a’Mharcaidh burn rises on the high ground of Inshriach and Invereshie National Nature Reserve, then flows through Inshriach Forest and neighbouring farmland before joining the River Feshie below Lagganlia. The burn was altered and straightened over 150 years ago to facilitate the floating of logs to a local mill. The surrounding land use is still forestry, but the landowner, Forestry and Land Scotland want to restore the watercourse to a more natural state and improve the surrounding wetland habitats. This work is being undertaken as part of the Cairngorms Connect project, funded by the Endangered Landscapes Programme. The site is designated as part of the River Spey Special Protection Area (SPA) for salmon and is also part of the Cairngorms Special Area of Conservation (SAC). The restoration work is designed to improve the condition of habitats locally that will benefit both of the designated areas and the work must be carried out sensitively to avoid damage or pollution. The ecological consultants EnviroCentre have produced a study and options appraisal for restoration of a 1km straightened section of the burn, which can be sub-divided into two reaches, the upper reach and lower reach. The approved design involves the excavation of a relict channel which has been identified by drone survey beside the lower reach, the harvesting and transportation of recently windblown trees close to the site to form the large wood structures and the installation of a range of large wood structures throughout the upper and lower reaches. The large wood structures serve a range of purposes and the details of locations and engineering design are provided in the attached ‘673614_Allt a' Mharcaidh_Design Brief 230118’ and the ‘673614_Allt a' Mharcaidh_Design Risk Assessment 230118’. The design consists of 21 lateral structures dug into the banks and 1 medial structure dug into the bed of the burn in the upper reach and 3 log jams and 6 medial blockages in the lower reach to discourage flow returning to the canalised channel and 1 upstream tie in to divert the burn into the excavated relict channel.