JBA Consulting appointed Temple on behalf of the Environment Agency to undertake a study into the potential effects of piling on local ornithological receptors.
The study was commissioned due to concerns from Natural England regarding future piling activities on the banks of the River Itchen as part of the River Itchen Flood Alleviation Scheme (RIFAS) and the potential effect this may have on nearby Solent and Southampton Water Special Protection Areas (SPA). These designated areas are home to various breeding and non-breeding bird species that could be disturbed by noise.
Whilst the construction of RIFAS had not yet begun, there was an opportunity to undertake source measurements of sheet piling at the redevelopment of Centurion Business Park (CBP), which included a new sheet pile wall behind the current timber wall on the banks of the River Itchen. The business park is located on the east bank of the River Itchen, adjacent to the A3024 and approximately 800m from Chessel Bay Nature Reserve which lies within the SPA and provides suitable habitat for both foraging and overwintering birds. As part of the scope, Temple organised a visit to the site and took source noise and vibration measurements of sheet piling.
Measurements were undertaken during core hours whilst the piling rig and other plant were in operation. Measurements captured several full cycles of piling activity and included ‘hard’ and ‘soft’ piling. Notes were taken on-site, including when piling was active, distances to the piling, any screening or reflections and any influence of other plants or other sounds.
Attended noise monitoring was carried out at and around the nature reserve at six locations (AN5 – AN10 in the figure below) to characterise the prevailing noise environment in the absence of the piling works, to capture source noise levels of road and rail, and to understand whether sheet piling from CBP was audible at the nature reserve.
Measurement locations were selected to be representative of places where birds may be sensitive to noise or to gather noise level data from the local noise sources such as roads and trains, which could then be integrated into the noise model and allow for predictions of noise from these sources.
The measurements consisted of capturing noise levels at each designated location over 15-minute intervals, which were repeated 2 to 3 times during the course of the day. To measure noise from road and rail sources, methodologies from CRTN and CRN standards were employed.
A 3D noise model was created using Ordnance Survey data and national LIDAR data and calibrated using noise levels recorded during the survey. This included noise inputs from the following sources:
- Railway noise from the Southampton to Portsmouth Coastal Line (SPCL)
- Road traffic noise from the A3024 and Athelstan Road
- Industrial noise from the nearby metal cycling works
- Sheet piling noise from source measurements at Centurion Business Park
The model showed a good correlation between measured noise levels and predicted levels, with the loudest sources in the model also correlating with the same source that was noted as dominant during the surveys.
Noise contours were produced using the noise model, based on LAeq noise levels from a typical 1-hour period during the daytime. The following five scenarios were accounted for (an example contour plot showing scenario 5 is provided below for information):
- Scenario 1 – road traffic from the A3024 and Athelstan Road and rail traffic from the SPCL only
- Scenario 2 – sheet piling noise contributions only
- Scenario 3 – road, rail and noise contributions from the scrap metal works
- Scenario 4 – road, rail and noise contributions from sheet piling (no metal works)
- Scenario 5 – road, rail, sheet piling and noise from the scrap metal works
