The development and application of an instrument array to measure the concentration of silt and sand in the overflow from aggregate dredgers
- Reference:
- 08/P70
- Organisation:
- HR Wallingford Ltd
- Amount Funded:
- £59,700
- Status:
- Complete
Background
Most of the UK fleet of aggregate dredgers are fitted with a
number of deck level overflows along each side of the vessel. For
many years the sampling and concentration measurement of the
overflow mixture has been of interest to the Aggregate Dredging
Industry as this is one of the more significant pathways for their
activities to impact on the marine environment. This project aims
to deliver a safe and robust method for the sampling and
measurement of the overflow mixture.
Progress
An opportunity to collect data arose either side of a plume
monitoring field survey being undertaken for the East Channel
Association. Over an 11 day period in September 2008 instruments
were installed aboard the A-Class aggregate dredger "Arco Axe"
whilst working in the Thames, Eastern English Channel and East
Coast Regions. The instruments measured levels of turbidity in the
overflow and water samples were remotely collected for post
calibration purposes. Detailed records of the way in which the
hopper was being loaded were also made.
Looking ahead
Water samples collected during September are currently being
analysed for silt and sand concentrations. Processing of the
turbidity data will commence once these results are available.