- 1st June 2021
- Posted by: Dom Senior
- Category: Projects
Location: Hendredenny, Caerphilly Client: Redrow Homes PLC
Redrow Homes Plc asked us to undertake a siltation survey of a site in Hendredenny, Caerphilly before construction began on a new property development. The site is on a steep incline, with two drainage ditches at the site boundary discharging into the Nant yr Aber main river located at the foot of the slope. Redrow Homes Plc were concerned that fine sediment would be mobilised during the construction of the property development and conveyed into the Nant yr Aber, leading to a degradation of the geomorphology and ecology of the main river. In Wales, significant degradation to the condition of a main river could lead to legal action from Natural Resources Wales (NRW).
JBA Geomorphologists undertook a site survey in order to establish the current sediment transport patterns, and to identify any potential sources of fine sediment that could lead to siltation off the Nant yr Aber. This involved a detailed geomorphological investigation of a number of key aspects of the site, including the drainage ditches to the north and south of the site and the Nant-yr-Aber. Each watercourse surveyed was split up into distinct reaches characterised by geomorphological and ecological features, such as bed material, riparian vegetation, man made structures and invasive species. Based on the observations made whilst visiting the site, our team of Geomorphologists were able to identify potential sources of sediment, barriers to sediment transport and areas of poor ecological condition on the site. The primary conclusion of the siltation survey at Hendredenny is that the current risk of fine sediment input into the Nant yr Aber is considered to be low.
The siltation survey and subsequent geomorphology assessment undertaken by our team provides Redrow Homes Plc technical advice on the current sediment transport patterns on the site, and the current risk of siltation in the Nant yr Aber. The information and conclusions drawn in the geomorphology assessment can help inform any siltation mitigation measures Redrow Homes Plc decide to implement on site during the construction phase, to limit fine sediment input into the Nant-y-Aber and maintain the current geomorphological and ecological condition of the watercourse.