Reviewing the UK’s Action Levels for the Management of Dredged Material

Jemma-Anne Lonsdale,Andrew Griffith,Lee Warford,Chris Vivian,Claire Mason,Jon Barber,David Sheahan,Clare Hynes,Philippe Bersuder,Adil Bakir

doi:10.3390/geosciences12010003

Jemma-Anne Lonsdale, Andrew Griffith + Show 8 more

Open Access

https://doi.org/10.3390/geosciences12010003

Copy DOI

Abstract

Action Levels (ALs) are thresholds which are used to determine whether dredged material is suitable for disposal at sea by providing a proxy risk assessment for potential impacts to biological features such as fish and benthos. This project tested proposed scenarios for changes to the UK Action Levels to determine the likely implications for navigational dredge licensing in England and Wales. Approximately 3000 sample data records from 2009 to 2018 were collated with varying numbers of concentrations for contaminant parameters including trace metals, organotins, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). Initially, these data were assessed using current ALs to determine the percentages of the samples with levels below AL1 (generally acceptable for disposal), between AL1 and AL2 and those showing levels above AL2 (generally unacceptable for disposal). These results were then used to compare with the results of the proposed new AL scenarios for each contaminant type derived from literature reviews and historic data. The results indicate that there are changes to the ALs which could be made such as updating the current ALs with the revised ALs, as well as the introduction of ALs where there are currently none set. The benefits of changing the ALs include reducing contaminant disposal to the marine environment and increased transparency in decision making. Any proposed scenarios will need to be phased in carefully in full liaison with stakeholders.

Highlights

As a seafaring island, the UK relies heavily on the maritime industry for the import and export of goods as well as for tourist and recreational activities to support the economy [1].In order to keep the ports, harbours and marinas accessible for the aforementioned activities, regular clearance of the approach channels and berths are required through dredging [2].Dredging can be for maintenance or for capital [3] but both require a MarineLicence from the regulator.Such dredging campaigns require an assessment of their potential impacts on the marine environment including chemical contamination [4]
The proportion of the sample results between the current Action Level 1 (AL1) and Action Level 2 (AL2) varied between 32% and 75% whilst the proportion of samples below AL1 varied between
It should be noted that while the revised AL1s [7] for Polycyclic Aromatic Hydrocarbons (PAHs) were for 17 individual PAHs, here we have extended this to include the 22 individual/cluster PAHs that are routinely analysed for marine licensing

Summary

Introduction

Act 2008 depending on the particulars of the development) Such dredging campaigns require an assessment of their potential impacts on the marine environment including chemical contamination [4]. In line with international obligations and guidelines, the UK assesses chemical contamination in sediments by comparison with Action Levels (ALs) [4,5]. Sediments with contaminant concentrations lower than AL1 are generally considered acceptable for disposal at sea, pending other considerations such as physical suitability for the disposal site and potential beneficial uses. The average background for each region was calculated for this demonstration, and these were used to compare with the current ALs. No regional background concentrations were developed for mercury. Note that for all cases, regional background is most protective and regional background X3 is the most permissive

Objectives

Methods

Results

Discussion

Conclusion