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Sediment Quality Assessment Sediment Quality Assessment and Management Framework and Management Framework
for Dam Removal Projectsfor Dam Removal ProjectsBrian Graber & Karen Pelto Brian Graber & Karen Pelto Riverways Program, Massachusetts Fish & GameRiverways Program, Massachusetts Fish & Game
Joseph Rathbun Joseph Rathbun Water Bureau, Michigan Dept. of Environmental QualityWater Bureau, Michigan Dept. of Environmental Quality
James TurekJames TurekNOAA Restoration CenterNOAA Restoration Center
Laura WildmanLaura WildmanAmerican RiversAmerican Rivers
Basic Concepts: Basic Concepts: Reservoirs are Sediment TrapsReservoirs are Sediment Traps
Many trap Many trap 95 %95 % of the sediment that enters of the sediment that enters them from upstreamthem from upstream
LargeLarge sediment particles typically form sediment particles typically form deltas at upstream enddeltas at upstream end
SmallSmall sediment particles typically sediment particles typically transported farther into reservoirtransported farther into reservoir– Many contaminants typically bind to small particlesMany contaminants typically bind to small particles
Basic Concepts: Issues with Basic Concepts: Issues with Contaminated SedimentContaminated Sediment
Direct Direct toxicitytoxicity to organisms to organisms– AcuteAcute– ChronicChronic
BioaccumulationBioaccumulation in organisms in organisms
Alter Alter benthic communitybenthic community
Contaminate overlying Contaminate overlying waterwater
Affect disposal of Affect disposal of dredged materialdredged material
Sediment Assessment Framework
Reconnaissance and/or definitive survey
SQC exceeded
Analyze transport capacity & downstream sensitivity
Low transport capacity
High transport capacity
Not bioavailable Bioavailable
Initial screening indicates sediment contamination likely
SQC not exceeded
(Optional)
Sediment ManagementFramework
Initial Landscape-Level Initial Landscape-Level ScreeningScreening
Screen impoundment Screen impoundment sediment quality based sediment quality based on on landscape-level GISlandscape-level GIS informationinformation
Screening can flag an Screening can flag an impoundment, impoundment, watershed, or regionwatershed, or region for for likely contaminantslikely contaminants
Predictive Model - RISQAPredictive Model - RISQA
RRegionalegional
IImpoundedmpounded
SSediment ediment
QQualityuality
AAssessmentssessment
Working with USGSWorking with USGS
Probabilistic model to Probabilistic model to estimate:estimate:
– Sediment quantitySediment quantity– Trace elementsTrace elements– Organic contaminantsOrganic contaminants
Developing and Validating RISQADeveloping and Validating RISQA
Compile existing data on sediment quality Compile existing data on sediment quality and quantity in impoundmentsand quantity in impoundments
Field assess volume and quality of sediment Field assess volume and quality of sediment in selected impoundmentsin selected impoundments
Develop and validate a GIS-based model for Develop and validate a GIS-based model for predicting sediment quantity and quality predicting sediment quantity and quality based on basin characteristicsbased on basin characteristics
*preliminary data**preliminary data*
HazardHazard ImpoundmentImpoundment PEC PEC exceedancesexceedances
Sig.Sig. PXZ-001PXZ-001 nonenone
Sig.Sig. D2Z-008D2Z-008 PAHPAH
HighHigh UXZ-001UXZ-001 Cd, Cu, Pb, CrCd, Cu, Pb, Cr
Sig.Sig. NUZ-001NUZ-001 CuCu
LowLow HKZ-001HKZ-001 nonenone
nonenone LVZ-001LVZ-001 CrCr
LowLow A2Z-001A2Z-001 nonenone
LowLow PTZ-001PTZ-001 Pb, PAH, PCBPb, PAH, PCB
Sig.Sig. FTZ-001FTZ-001 Cd, PbCd, Pb
Sig.Sig. AJZ-001AJZ-001 DDEDDE
Combine Combine dam hazard classificationdam hazard classification with contaminant with contaminant assessment?assessment?
Preliminary Modeling ResultsPreliminary Modeling ResultsPreliminary Modeling ResultsPreliminary Modeling Results
Preliminary regression analyses indicate that Preliminary regression analyses indicate that sediment contamination variability may be sediment contamination variability may be best explained by:best explained by:
• Percent impervious areaPercent impervious area
• Number of point sources Number of point sources (NPDES, 21E, underground tanks, etc.)(NPDES, 21E, underground tanks, etc.)
Additional impoundments are currently Additional impoundments are currently being assessed to validate the modelbeing assessed to validate the model
Preferred Survey Design ProcessPreferred Survey Design Process
1.1. Establish Establish study objectivesstudy objectives, evaluate , evaluate existing data, etc.existing data, etc.
2.2. Conduct Conduct reconnaissancereconnaissance surveysurvey
3.3. Refine study objectivesRefine study objectives - Choose minimum number of stations that - Choose minimum number of stations that
are representative of study areaare representative of study area
4.4. Conduct Conduct definitive surveydefinitive survey
Reconnaissance SurveyReconnaissance Survey
ObjectivesObjectives– Sampling accessSampling access– Sample collectabilitySample collectability– Qualitatively assess nature and extent of depositsQualitatively assess nature and extent of deposits– Quantitatively collect a small number of (silt) Quantitatively collect a small number of (silt)
sediment quality samplessediment quality samples
EquipmentEquipment– Probing rod or tubeProbing rod or tube– Small grab or core samplerSmall grab or core sampler– GPSGPS
Reconn. Survey – Mud Music Reconn. Survey – Mud Music ♫♫
Use Use hollow metal tubehollow metal tube to identify surface to identify surface sediment type:sediment type:RockRock = bounce & clang = bounce & clangClayClay = bounce & silent = bounce & silentGravelGravel = crunch = crunchSiltSilt = silent, penetration = silent, penetrationSandSand = silent, no penetration = silent, no penetration
Reconn. sample from silt portionReconn. sample from silt portion
Moving from Reconn Survey to Moving from Reconn Survey to Definitive Survey Definitive Survey
Combine:Combine:Reconn survey infoReconn survey infoRegulatory guidelines/requirementsRegulatory guidelines/requirements– State specificState specific
Watershed screening information (due Watershed screening information (due diligence)diligence)Best professional judgmentBest professional judgment
To determine if additional assessment is To determine if additional assessment is neededneeded
ex. headwaters; run-of-river; gravelex. headwaters; run-of-river; gravel
Definitive SurveyDefinitive Survey
ObjectiveObjective
– Quantitatively Quantitatively establish magnitude establish magnitude and extent of contaminationand extent of contamination
EquipmentEquipment
– Grab or core samplersGrab or core samplers
– GPSGPS
Largely the same as reconn…Largely the same as reconn…
Definitive Survey Definitive Survey Sampling DesignSampling Design
How manyHow many samples will be collected samples will be collected
WhereWhere samples will be collected samples will be collected
HowHow samples will be collected samples will be collected
Sampling Design – How Many?Sampling Design – How Many?
Most subjective part of survey designMost subjective part of survey design
BBest est PProfessional rofessional JJudgment and regulatory udgment and regulatory guidelines guidelines – Minimum 50-ft diameter “hot spots”?Minimum 50-ft diameter “hot spots”?
$$$$$$$$ (affects sampling resolution) (affects sampling resolution)
Elipgrid-PCElipgrid-PC software software– Computes probability of locating “hot spots”Computes probability of locating “hot spots”– Based on total area, grid spacing, and potential Based on total area, grid spacing, and potential
hot spot size, shape, orientationhot spot size, shape, orientation– Can use to determine number of samplesCan use to determine number of samples
Sampling Design – Where?Sampling Design – Where?
Objective Objective of the studyof the study
Cost-effectivenessCost-effectiveness– Use Elipgrid-PCUse Elipgrid-PC
Sediment Sediment patternspatterns
Simple Random SamplingSimple Random Sampling
DamDam
Systematic Grid SamplingSystematic Grid Sampling
DamDam
Subjective SamplingSubjective Sampling
DamDam
OutfallOutfall
Stratified Random SamplingStratified Random Sampling
DamDamGravelGravel
BarBar
Silt BarSilt Bar
Sample Collection: Grab SamplingSample Collection: Grab Sampling
More “recent” sediments (?)More “recent” sediments (?)
Mixed, mobile surface layer Mixed, mobile surface layer – (grab 2 – 24 L)(grab 2 – 24 L)
““Biologically active” zoneBiologically active” zone– Upper 10 cm or soUpper 10 cm or so Ponar SamplerPonar Sampler
Sample Collection: Core SamplingSample Collection: Core Sampling
Recent to older sediment Recent to older sediment Stratified, less mobile depositsStratified, less mobile deposits– important if mobilized during removalimportant if mobilized during removal
Hand corersHand corers– Cores = a few feet long, 2” diameterCores = a few feet long, 2” diameter– Shallow waterShallow water
Gravity corers, piston corers, etc.Gravity corers, piston corers, etc.– Cores < 5’ longCores < 5’ long– Deep waterDeep water
VibrocorersVibrocorers– Cores = up to 20’ long, 4” diameterCores = up to 20’ long, 4” diameter– Deep water (> 1,000’)Deep water (> 1,000’)– Less disruption of sediment columnLess disruption of sediment column
Challenges in gravel, clayChallenges in gravel, clay
Sample Analysis - ChemicalSample Analysis - Chemical
Often only testing done – least Often only testing done – least expensiveexpensive
Methods well-establishedMethods well-established
Common analytes = Common analytes = metals, PCBs, PAHsmetals, PCBs, PAHs
Sediment Analysis – Sediment Analysis – ToxicityToxicity
Done less often than Done less often than chemical testingchemical testing– greater expensegreater expense– requires larger samplerequires larger sample
Why do toxicity testing?Why do toxicity testing?– Integrates effectsIntegrates effects– Uses important food chain Uses important food chain
organismsorganisms– Direct proof of effectsDirect proof of effectsNo effect = no pollution (?)No effect = no pollution (?)
Midge larvaeMidge larvae
AmphipodAmphipod
Data Interpretation:Data Interpretation:Sediment Quality CriteriaSediment Quality Criteria
Uses:Uses:
Evaluate sediment qualityEvaluate sediment quality
Establish cleanup objectivesEstablish cleanup objectives
Assess suitability for disposalAssess suitability for disposal
Assess suitability for Assess suitability for natural erosion & natural erosion & depositiondeposition
Agree to at start of projectAgree to at start of project
Chemical Concentration SQCChemical Concentration SQC
Tied to Tied to biological effectsbiological effects– Cu > X ppm = mortality in mayfliesCu > X ppm = mortality in mayflies
Usually tied to Usually tied to toxicitytoxicity rather than rather than bioaccumulation or changes in bioaccumulation or changes in community structure or human healthcommunity structure or human health
More often More often guidelinesguidelines than than regulationsregulations– vary state to statevary state to state
Database Chemical SQCDatabase Chemical SQC
PEC = probable effects concentration (above which effects are probable)PEC = probable effects concentration (above which effects are probable)
TEC = threshold effects concentration (below which effects rarely observed)TEC = threshold effects concentration (below which effects rarely observed)
Incr
easi
ng
Co
nce
ntr
atio
nIn
crea
sin
g C
on
cen
trat
ion
PresumedPresumed
NontoxicNontoxic
PresumedPresumed
ToxicToxic
PossiblyPossibly
ToxicToxic
PECPEC
TECTEC
Sediment Management Framework
Fullsediment removal
Partialsediment removal
Cap or isolate
Natural erosion& deposition
Stageddam removal
Low transport capacity and/or
high d/s sensitivity
High transport capacity and/or
low d/s sensitivity
Not bioavailable Bioavailable
(Optional)
Complete Dam Removal & Complete Dam Removal & Natural Erosion & DepositionNatural Erosion & Deposition
Issue:Issue: demonstrate transport & deposition will demonstrate transport & deposition will not:not:
Cause Cause long-termlong-term adverse physical habitat adverse physical habitat changes downstream or upstreamchanges downstream or upstream– Fill pools, bury riffles, etc. downstreamFill pools, bury riffles, etc. downstream– Upstream channel incisionUpstream channel incision
Increase Increase bioavailabilitybioavailability (exposure/mobilization) of contaminants(exposure/mobilization) of contaminants
Staged Dam Removal & Staged Dam Removal & Natural Erosion & DepositionNatural Erosion & Deposition
Issues:Issues:
1.1. Assess Assess engineering suitabilityengineering suitability of dam of dam for staged removalfor staged removal
2.2. Assess probability, magnitude, Assess probability, magnitude, impacts of higher, “pulsed” impacts of higher, “pulsed” water water flows and sediment loadsflows and sediment loads on on downstream geomorphology and downstream geomorphology and ecologyecology
3.3. ((PlusPlus issues for complete dam issues for complete dam removal)removal)
On-Site Isolation or CappingOn-Site Isolation or Capping
Issue:Issue: demonstrate that: demonstrate that:
Capping will reduce contaminant Capping will reduce contaminant availability to aquatic and terrestrial availability to aquatic and terrestrial ecosystems, and humansecosystems, and humans
Capping won’t disrupt remaining Capping won’t disrupt remaining ecosystemecosystem– Decrease riparian zone, wetlands, Decrease riparian zone, wetlands,
bottomlands, etc.bottomlands, etc.
Partial Removal of Hot SpotsPartial Removal of Hot Spots
Tasks:Tasks:
1.1. Locate Locate hot spotshot spots
2.2. Remove & disposeRemove & dispose of sediment of sedimentIn the “dry” or “wet”In the “dry” or “wet”
3.3. Demonstrate that remaining sediment Demonstrate that remaining sediment is is nontoxicnontoxic
4.4. Post-remediation Post-remediation monitoringmonitoring
Sediment Removal – Sediment Removal – “Wet” & “Dry”“Wet” & “Dry”
(HRC, Inc.)(HRC, Inc.)
(ECT, Inc.)(ECT, Inc.)
Full Removal of All SedimentFull Removal of All Sediment
Tasks:Tasks:
1.1. Identify Identify extentextent of contaminated sediment, of contaminated sediment, inin 3D3D
2.2. Characterize Characterize degreedegree of contamination, for of contamination, for disposal decisionsdisposal decisions
3.3. Assess potential disturbance of original Assess potential disturbance of original channel bedchannel bed
4.4. Remove & disposeRemove & dispose5.5. Post-remediation Post-remediation monitoringmonitoring
Sediment Quality and Management Options
Reconnaissance and/or definitive survey
SQC exceeded
Analyze transport capacity & downstream sensitivity
Low transport capacity
High transport capacity
Not bioavailable Bioavailable
Initial screening indicates sediment contamination likely
SQC not exceeded
(Optional)
Sediment ManagementFramework
Contaminated Sediment = Contaminated Sediment = Run Away?Run Away?
Dams as a Dams as a long-termlong-term sediment and sediment and contaminant management plan?contaminant management plan?
Reservoir = contaminant Reservoir = contaminant “time bomb”“time bomb”
For more information:For more information:– Brian Graber, [email protected] Graber, [email protected]– Joseph Rathbun, [email protected] Rathbun, [email protected]