7 Sediment Quality
7Sediment Assessment MethodologyBaseline ConditionsPredicted ImpactsMitigation MeasuresResidual ImpactsCumulative EffectsTransboundary EffectsUncertaintySummary7
Eastside Environmental Statement: Sediment Quality7Sediment Quality7.1IntroductionThis chapter of the Environmental Statement (ES) concerns the quality of the seabedsediments and how it could be affected by Eastside. Although no specific issues were raisedin the Town Planner’s Scoping Opinion (Government of Gibraltar (GoG), 2005 - seeAppendix A), dredging and marine works can affect marine sediment and give rise toimpacts on the environment in the following ways: Disturbance of contaminants into the water column; andDeposition of contaminants onto the seabed.Both of the above impacts relate to dredging activities during the construction phase of theproject. One of these impacts really concerns water quality but has been considered in thischapter because the marine sediment and its disturbance is the source and cause of thispotential impact.No impacts have been identified for sediment quality for the operational phase of Eastside.Potentially polluting discharges from the operation of Eastside are considered in Chapter 6on Water Quality.7.2Assessment Methodology7.2.1Baseline Environmental SurveyA sediment quality survey was conducted to ascertain the physical and chemical properties ofthe seabed. The survey area comprised the site of Eastside, coastal areas to the north intoSpain, coastal areas to the south as far as Europa Point, and potential offshore borrow areas.In total, 40 sediment samples were collected from the seabed’s surface using a van Veen grabsampler. Of the 40 samples taken, three were retained as individual samples representing theseabed around Eastside. The remaining the 37 samples were mixed to create compositesamples representing the seabed east of Eastside, the coastal areas to the north and south,and the potential borrow areas. In total, 13 individual and composite samples were derived,as identified in Table 7.1.The samples were analysed for metals, polychlorinated biphenyls (PCBs), petroleumhydrocarbons, poly-aromatic hydrocarbons (PAHs), tributyl-tin (TBT), phenols and totalcyanide (see Table 7.2). Analyses were carried out by a National Measurement AccreditationService (NAMAS) / UK Accreditation System (UKAS) accredited laboratory.Analyses for metals, PCBs, hydrocarbons, PAHs and TBT were included since these are theprincipal contaminants associated with marine sediments.Analyses for phenols and total cyanide were included as indicators of potentialcontamination from the rubble tip.The sediment samples were also subjected to other analyses (e.g. total organic carbon (TOC)content) to inform the impact assessments where appropriate.Doc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-1
Eastside Environmental Statement: Sediment QualityTable 7.1 Schedule of Samples for Sediment Quality Laboratory AnalysisSampleNo.Sample TypeSample PositionsSeabed Area Description1Composite1, 2, 3, 4 and 5Coastal area, Spain2Composite6, 7 and 8Coastal area, Eastern Beach / airport3Individual11Coastal area, Eastside Development4Individual13Coastal area, Eastside Development5Individual14Coastal area, Eastside Development6Composite9, 12, 16, 17 and 18Coastal area, Eastside Development7Composite19, 20 and 21Coastal area, Sandy Beach8Composite23, 24 and 25Coastal area, Governor’s Bay9Composite27, 28 and 29Coastal area, Windhill Beach toGreat Europa Point10Composite15, 31, 32, 33 and 34Northern borrow area11Composite35, 36 and 37Northern borrow area12Composite22, 26 and 39Southern borrow area13Composite30, 38 and 40Southern borrow area7.2.2Modelling Approach – Sediment PlumesAs described in Section 6.2, the sediment plumes released from dredging and reclamationactivities have been simulated using the Delft3D flow model developed as part of this study(see Appendix B). The flow model has been linked with the Delft3D morphological moduleDelft3D-Online Morphology to include the processes of sediment dispersion, taking intoaccount advection, diffusion and dispersion processes (see Section7, Appendix D). Themodelling produces a set of plots showing isolines of the maximum concentrations (in mg/l)of total suspended solids.7.2.3Modelling Approach – Sediment DepositionAs described in Section 6.2, the sediment deposition due to dredging and reclamationactivities have been simulated using the Delft3D flow model developed as part of this study(see Appendix B). The flow model has been linked with the Delft3D morphological moduleDelft3D-Online Morphology to include the processes of sediment dispersion, taking intoaccount advection, diffusion and dispersion processes (see Section7, Appendix D). Themodelling produces a set of plots showing isolines of the maximum thickness (in m) ofsediment deposition.Doc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-2
Eastside Environmental Statement: Sediment QualityTable 7.2 Schedule of Laboratory AnalysesParameterUnitsDetection kgZincmg/kg0.1mg/kgPCBs (28, 52,101, 118, 138, 153, 180)mg/kg0.0002mg/kgPetroleum hydrocarbons (GROs)mg/kgNone specifiedPAHs (US EPA 16)*mg/kg0.0001mg/kgTBTmg/kg 0.002mg/kgPhenolsmg/kgNone specifiedTotal cyanidemg/kg 5mg/kg* A standard suite of tests for PAHs, the US Environmental Protection Agency 16 Naphthalene, Acenaphthylene,Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene,Benzo(k)fluoranthene, Benzo(a)pyrene, Dibenzo(ah)anthracene, Benzo(ghi)perylene, Indeno (123-cd)pyrene.7.2.4Assessment Methodology – Sediment Quality CriteriaImpacts were assessed by comparing baseline survey data to established sediment qualitystandards and/or published research. There are no quantified environmental qualitystandards (EQSs) defining in situ quality for Gibraltar, European Union (EU) or UnitedKingdom (UK) sediments. At an EU level, guidance is given only for the substances underthe European Commission (EC) Dangerous Substances Directive List I as ‘standstill (nodeterioration)’.Without quantified Gibraltar, EU or UK standards, the following guidelines (i.e. assessmentcriteria) from other sources have therefore been used to assess the level of contaminationpresent in the seabed sediments and the potential impact on receptors: Sediment quality guideline action levels for assessing the disposal of dredged materialat sea in the UK (Centre for Environment, Fisheries and Aquaculture Science(CEFAS));Sediment quality criteria for the management of dredged material from Spanish ports(Centre for Studies and Experimentation on Public Works’ (CEDEX)); andCanadian sediment quality guidelines for the protection of aquatic life (CanadianCouncil of Ministers of the Environment (CCME)).CEFAS’s action levels (see Table 7.3) are non-statutory criteria used by the UK’sDepartment of the Environment, Food and Rural Affairs (DEFRA) as part of a weight-of-Doc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-3
Eastside Environmental Statement: Sediment Qualityevidence approach to licensing the disposal of dredged material at sea under the Food andEnvironment Protection Act 1985. The Action Levels act as potential triggers for furtherassessment and do not constitute pass or fail criteria. In this context, licence refusal isunlikely if contaminant concentrations are below Action Level 1 and likely if contaminantconcentrations are above Action Level 2, and further assessment may be required ifcontamination concentrations are between Action Levels 1 and 2.CEDEX’s sediment quality criteria (see Table 7.3) aim to control the management ofdredged material in Spanish waters. Sediment with 10% fine fraction ( 63µm) areregarded as clean. Sediment with 10% fine fraction require chemical characterisation withregard to the sediment quality criteria identified in Table 7.3. Sediment where concentrationsare below Action Level 1 can be disposed of at sea. Sediment where concentrations arebetween Action Levels 1 and 2 can be disposed of at sea subject to impact assessment andmonitoring. Sediment where concentrations are above Action Level 2 cannot be disposed ofat sea unless treated (IADC/CEDA, 1997).1065-0.011000.1CEFASActionLevel oleumHydrocarbons0.15ΣPAHs(US EPA tionLevel 1StatisticCadmiumΣ7PCBsTable 7.3 International Sediment Quality Guidelines (All units in mg/kg)CEFAS (UK) Action Levels for the Disposal of Dredged Material at SeaCEDEX (Spain) Action Levels for the Disposal of Dredged Materials at Sea from SpanishPortsCEDEXActionLevel 18012001001200.6100500-0.03--CEDEXActionLevel 22005100040060034003000-0.1--Canadian Sediment Quality Guidelines for the Protection of Aquatic -CanadianPEL41.64.21601081120.7-271-0.189--The CCME’s Canadian sediment quality guidelines (see Table 7.3) are derived from scientificinformation on the biological effects of sediment-associated chemicals, including acute andchronic toxicological effects identified by laboratory tests and subtler effects identified byDoc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-4
Eastside Environmental Statement: Sediment Qualityfield surveys. The guidelines provide scientific benchmarks to be used as a basis forevaluating the toxicological significance of sediment chemistry data, and “thus to identify andfocus the cleanup of contaminated sites, to predict the impacts of activities from varioussectors on the aquatic environment, and to evaluate the effectiveness of proposed or existingsite management strategies in protecting the aquatic environment” (CCME, 1999).The Canadian sediment quality guidelines for the protection of aquatic life constitutethreshold effect levels (TELs) and probable effect levels (PELs) that indicate in situ sedimentquality with respect to biological effects. The two levels form three biological effects rangesfor chemical contaminants as follows: Minimal effect range below the TEL where adverse biological effects occur rarely;Possible effect range between the TEL and PEL where adverse biological effectsoccur occasionally; andProbable effect range above the PEL where adverse biological effects occurfrequently.The TEL also acts as an interim sediment quality guideline (ISQG) level (CCME, 1999).Cole et al (1999) recommend that “in the absence of any UK standards, these guidelines canbe used as a first approximation in assessing whether organisms are at risk from sedimentconcentrations of toxic substances.” Table 7.3 shows the TELs and PELs for metals.Nickel is not included under the Canadian guidelines.7.2.5Assessment Methodology – Water Quality CriteriaThe EC Dangerous Substances Directive was adopted in 1976 to control pollution caused bycertain dangerous substances on the aquatic environment. The Directive established List Isubstances, which are regarded as particularly dangerous because of their toxicity, persistenceand bioaccumulation. Pollution by these substances must be eliminated. List II substancesare regarded as less dangerous but have a deleterious effect on the aquatic environment;input of these substances must be reduced.The Dangerous Substances Directive stipulates uniform emission standards (UESs, alsoknown as limit values) and environmental quality standards (EQSs) as approaches for thecontrol of List I substances. For List II substances, all member states are required toestablish EQSs on a national level. EQSs for List I and List II substances have beenimplemented in the UK and are shown on Tables 7.4 and 7.5 respectively. These EQSs forList I and List II substances form the impact assessment criteria for water quality concerningdangerous substances.Table 7.4 Selected List I Dangerous Substances*SubstanceEQS TypeEstuarine EQS(annual average, µg/l)Mercury (dissolved)Annual average0.5Cadmium (dissolved)Annual average5* EQS List I taken from www.environment-agency.gov.uk, **Total concentration (i.e. without filtration) unless specified, *** allHCH isomers, including LindaneDoc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-5
Eastside Environmental Statement: Sediment QualityTable 7.5 Selected List II Dangerous Substances*SubstanceEQS TypeEstuarine EQS(annual average, µg/l)Arsenic (dissolved)Annual average25Chromium (dissolved)Annual average15Copper (dissolved)Annual average5Lead (dissolved)Annual average25Nickel (dissolved)Annual average30Tributyl tinMaximum concentration0.002Zinc (total)Annual average40*The full EQS List II is available on www.environment-agency.gov.uk7.2.6Impact SignificanceIn order to provide a consistent framework for considering and evaluating impacts, thefollowing terminology has been adopted: Negligible - the impact is not of concern;Minor adverse - the impact is undesirable but of limited concern;Moderate adverse - the impact gives rise to some concern but it is likely to be tolerable(depending on its scale and duration);Major adverse - the impact gives rise to serious concern; it should be considered asunacceptable unless unavoidable by best practicable means;Minor beneficial - the impact is of minor significance but has some environmentalbenefit;Moderate beneficial - the impact provides some gain to the environment; andMajor beneficial - the impact provides a significant positive gain.7.3Baseline Conditions7.3.1Survey DataA full version of the survey data collected during the EIA process and used to inform thebaseline environmental conditions are presented in Appendix E to this ES.7.3.2Chemical ConditionsA summary of the survey data for a range of contaminants (metals, PCBs, petroleumhydrocarbons (as GROs), PAHs, and TBT) is given in Table 7.6.The survey recorded concentrations of all metals, PAHs and petroleum hydrocarbons(although some results for mercury and petroleum hydrocarbons were below the analyticaldetection limit), suggesting that the baseline environment exhibits concentrations of theseparameters at levels that can be considered to be above uncontaminated environmentalconditions.The survey recorded concentrations of summed PCBs and TBT below the analyticaldetection limit (with the exception of one TBT result), suggesting that the baselineenvironment does not exhibit elevated concentrations of these parameters.Doc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-6
Eastside Environmental Statement: Sediment QualityThe survey data are compared against three international sediment quality guidelines toinform the baseline environment conditions, particularly for the parameters present inelevated concentrations. The comparisons are presented in Table 7.6.Compared against the CEFAS Action Levels applied in the UK, the sediment containscontaminants at concentrations that are generally below Action Level 1 with the exception ofchromium and nickel which are at concentrations between Action Levels 1 and 2.Therefore, the data suggest that the contaminants present in the sediment are sufficiently lowsuch that an application for a licence to dispose of the sediment (as dredged material) at seais likely to be successful (in terms of contaminants).Compared against the CEDEX Action Levels applied in Spain, the sediment containscontaminants at concentrations that are all below Action Level 1. Therefore, the datasuggest that the contaminants present in the sediment are sufficiently low such that thesediment (as dredged material from a Spanish port) could be disposed of at sea (in terms ofcontaminants).Compared against the sediment quality guidelines applied by the CCME in Canada, thesediment contains contaminants at concentrations that are generally below the TEL with theexception of arsenic which is at concentrations between the TEL and PEL. Therefore, thedata suggest that the contaminants in the sediment are sufficiently low such that they are inthe minimal effect range where adverse biological effects occur rarely.Doc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-7
Eastside Environmental Statement: Sediment QualityTBTPetroleumHydrocarbonsΣ7PCBs(US EPA StatisticChromiumTable 7.6 Statistical Summary of Sediment Data and Comparison against International Sediment Quality GuidelinesStatistical Summary of Sediment DataNo. samples131313131313131313131313Min (mg/kg)7.820.01522.3343.553.67 0.00546.47814.880.009 0.0001 1 0.001Max 0720.324 0.00014.7 0.031Median (mg/kg)9.2520.01933.5745.6857.928 0.00572.3422.9750.141 0.0001 0.1 0.001Comparison against CEFAS (UK) Action Levels for the Disposal of Dredged Material at SeaNo. samples CEFAS Action Level 19130121213012n/a131313No. samples CEFAS Action Level 1 - 24013110131n/a000No. samples CEFAS Action Level 200000000n/a000Comparison against CEDEX (Spain) Action Levels for the Disposal of Dredged Materials at Sea from Spanish PortsNo. samples CEDEX Action Level 11313131313131313n/a13n/an/aNo. samples CEDEX Action Level 1 - 200000000n/a0n/an/aNo. samples CEDEX Action Level 200000000n/a0n/an/aComparison against Canadian Sediment Quality Guidelines for the Protection of Aquatic LifeNo. samples Canadian TEL01313121213n/a13n/a13n/an/aNo. samples Canadian TEL - PEL1300110n/a0n/a0n/an/aNo. samples Canadian PEL000000n/a0n/a0n/an/aDoc No: 048 Issue: 1 Rev: 0 Date: 30 July Disciplines\f.Environmental\ES Submission July 2007\Final ES7-8
Eastside Environmental Statement: Sediment Quality7.4Predicted Impacts7.4.1Construction Phase: Impact on Water Quality due to Sediment DisturbanceDredging for Eastside has the potential to disturb and release sediment-bound chemicalcontaminants into the overlying water column. This effect could increase concentrations incoastal waters and affect water quality with regard to EQSs required by the EC DangerousSubstances Directive (see Tables 7.4 and 7.5).To assess the potential impact on compliance with the EQSs, a sediment-water partitioningapproach has been used. This approach assumes that the critical factor in sediment toxicityis the concentration of the contaminant in the interstitial water. The potential impactis assessed by identifying whether contaminant concentrations in the in situ sediment couldcause concentrations in the interstitial water that exceed the water quality criteria (i.e. theEQSs for contaminants as identified by the EC Dangerous Substances Directive). Theassessment uses sediment criteria derived from equilibrium partitioning to provideconcentrations that may be considered as environmentally safe concentrations - that is,where contaminant concentrations in a seabed sediment's interstitial water are less than theEQSs, they are not expected to cause an impact on the quality of the overlying water. Thesediment criteria are calculated using published partition coefficients (Webster and Ridgway,1994). These express the relationship between the contaminant concentration in thesediment and the surrounding water and are referred to as Koc. The
CEDEX’s sediment quality criteria (see Table 7.3) aim to control the management of dredged material in Spanish waters. Sediment with 10% fine fraction ( 63µm) are regarded as clean. Sediment with 10% fine fraction require chemical characterisation with regard to the sediment quality criteria identified in Table 7.3. Sediment where .
BMP C241: Temporary Sediment Pond Purpose Sediment ponds remove sediment from runoff originating from disturbed areas of the site. Sediment ponds are typically designed to remove sediment no smaller than medium silt (0.02 mm). Consequently, they usually reduce turbidity only slightly.
the sediment fall velocity (and hence sediment residence time and fate) is critical to both short-term sediment transport predictions and long-term shoreline restoration efforts. However, this parameter can be difficult to measure and it can be complicated by cohesive sediment flocculation. The problem is
Draft Sediment Analysis Guidelines for Dam Removal August 4, 2011 Jennifer Bountry, M.S., P.E. . –Revisit predictions and revise analysis and monitoring plan as needed Compare impacts to background sediment conditions (dynamics) within current . –upstream supply for fine sediment 0 1 0.01 0.1 1 10 100 V s / Q s Reservoir Sediment .
In 1996, the Colorado Sediment Task Force was convened with the goal of developing a guidance document for implementing the narrative sediment standard. The product of the Task Force was the Implementation Guidance for Determining Sediment Deposition Impacts to Aquatic Life in Rivers and Streams (“Sediment Guidance”). The Sediment
Estuarine sediment, UK 31 particles kg 1 Thompson et al., 2004 Subtidal sediment, UK 86 particles kg 1 Thompson et al., 2004 Subtidal sediment, Florida 214 particles l 1 Graham and Thompson, 2009 Subtidal sediment, Maine 105 particles l 1 Graham and Thompson, 2009 Harbour sediment, Sweden 50 particles l 1 Norén, 2008
analyzing samples, internal quality assurance and quality control, and validity of the sediment-analysis results also are described. The report includes a list of references cited and a glossary of sediment and quality-assurance terms. Introduction This report describes a quality-assurance (QA) plan for the U.S. Geological Survey (USGS) Kentucky
The Dam Removal Analysis Guidelines for Sediment will . The release of fine sediment could affect water quality for the . Discussion on sediment effects 9. Develop monitoring and adaptive management plan An overview of the general guideline steps are presented in Figure 1.
guided inquiry teaching method on the total critical thinking score and conclusion and inference of subscales. The same result was found by Fuad, Zubaidah, Mahanal, and Suarsini (2017); there was a difference in critical thinking skills among the students who were taught using the Differentiated Science Inquiry model combined with the mind
