CEFAS - Action Levels



Use of Action Levels in Dredged Material Assessments(Edit)

Action Levels are used as part of a ‘weight of evidence’ approach to assessing dredged material and its suitability for disposal to sea. These values will be used in conjunction with a range of other assessment methods e.g. bioassays, as well as historical data and knowledge regarding the dredging site, the material's physical characteristics, the disposal site characteristics and other relevant data, to make management decisions regarding the fate of dredged material. We are currently in the process of testing sediment bioassays to provide further information on the characteristics of dredged material. This integrated approach is in line with recent discussions regarding weight of evidence approaches to environmental management of sediments. It considers balancing multiple lines of evidence concerning ecological assessment as an aid to decision making.

In general, contaminant levels in dredged material below Action Level 1 are of no concern and are unlikely to influence the licensing decision. However, dredged material with contaminant levels above Action Level 2 is generally considered unsuitable for sea disposal. The latter situation most often applies only to a part of a proposed dredging area and so that area can be excluded from disposal at sea and disposed of by other routes e.g. landfill. Dredged material with contaminant levels between Action Levels 1 and 2 requires further consideration and testing before a decision can be made.


Contaminant / CompoundAction Level 1Action Level 2
mg/kg Dry Weight (ppm)
Organotins; TBT DBT MBT0.11
PCB's, sum of ICES 70.01none
PCB's, sum of 25 congeners0.020.2

Table from Environmental Resources Managements - relating to Able UK Ltd marine license application

ContaminantUnitCEFAS AL1CEFAS AL2DutchCanadaIntertidal (Surface)Subtidal (Surface)Subtidal (Vibrocore)CEFAS Samples
Min MaxMinMaxMinMaxMinMax
Heavy metals
Arsenicmg/kg20100297.2413.8 18.914.329.63.3830.97.550
Cadmiummg/kg0.450.80.70.296 0.5330.1850.440.1410.4690.120.46
Chromiummg/kg4040010052.331.6 45.710.735.4442.51596
Coppermg/kg404003518.723.5 31.4749.93.1626.61153
Leadmg/kg505008530.235.4 54.626.757.72.3448.88.8135
Mercurymg/kg0.330.30.13<0.14 <0.14<0.140.177<0.14<0.1400.36
Nickelmg/kg202003515.922.1 32.410.2194.1328.41453
Zincmg/kg130800140124112 14566.711513.113156287
Organo tins & PCBs
PCBs - sum of ICES 7µg/kg100---<3 <3<3<3<3<30.000870.03022
Acenaphtheneµg/kg100--6.71 33.59 Action Level29.8 50.918.541.4<854.80.3533.59
Acenaphthyleneµg/kg100--5.87118.58 2 19.9 28.3<1227.5<1243.60.8118.58
Anthraceneµg/kg100--46.962 11138.595.2<161271.53154.13
Benzo(a)anthraceneµg/kg100---74.8169 28290268<142378.41443.13
Benzo(a)pyreneµg/kg100--88.8Dutch 167 258118278<152508.45575.9
Chryseneµg/kg100--108Standard1s 52 24379.4189<101865.65371.13
Dibenz(ah)anthraceneµg/kg10--6.22<23 48.6<2343.32<2345.72.2104.04
Fluorantheneµg/kg100--113304 507165377<174339.99850.17
Fluoreneµg/kg100--21.2Canadian4 6.7 72.425.472.4<10753.33210.17
Naphthaleneµg/kg100--34.G6 uideline1s5 023752.6177<91129.55567.79
Phenanthreneµg/kg100--86.7251 406127264<1528712.75848.19
Pyreneµg/kg100--153291 464162347<153759.22668.9