graber - dam removal project overview

8/6/2019 Graber - Dam Removal Project Overview

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Dam RemovalDam RemovalProject OverviewProject Overview

Dam Removal DemystifiedDam Removal Demystified

North CarolinaNorth Carolina

June 14, 2011June 14, 2011

Brian GraberBrian Graber

American RiversAmerican Rivers


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Removing a dam seems like

an intimidating process


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Youd like to manage a

project


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Goals:

1) Understand thedam removal process

2) Be able to scope

out the componentsof a project


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Expect that projects will take3 years to complete

Year 1: Recon. andPrelim. Design Year 2: Designand Permitting Year 3:Implementation

Overall Process: Project StepsOverall Process: Project Steps


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The basic steps cover 4 major topics

Design/ConstructionDesign/ConstructionPermittingPermitting

FundraisingFundraising Social IssuesSocial Issues

Overall Process: Project StepsOverall Process: Project Steps


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Determine the challenges specific to your project

Sediment quantity

Sediment quality

Dam size

Dam condition

Impoundment size

Impoundment shape

Surrounding infrastructure

Surrounding environment

The depth of analysis should reflect the scale of the project:make easy projects easy and complex projects complex

Overall Process: Initial ReconnaissanceOverall Process: Initial Reconnaissance


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Step 1: The dam owner must be on

board with the project



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Several factors separate easyprojects from difficult projects

Land ownership Current dam uses Public interest


l f


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Several factors separate easyprojects from difficult projects

Contaminants T & E species Infrastructure


l /d


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Dam removal science/design

includes 6 components

DataDataCollection/Collection/

SurveyingSurveying

ProtectingProtecting

InfrastructureInfrastructure

SpeciesSpecies

ProtectionProtection

Hydrology/Hydrology/

HydraulicsHydraulicsSedimentSediment

ManagementManagement

SiteSite--SpecificSpecific

IssuesIssues


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Consider long-term benefits vs. short-term impacts

ComplexityComplexityContinuityContinuity

Flow RegimeFlow Regime

Water QualityWater Quality

Design Components: LongDesign Components: Long--Term Benefits/ShortTerm Benefits/Short--TermTerm


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Some short-term impacts occurduring construction

Sediment movement Construction access Habitat change



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There are 3 potential long-term impactsif not managed well

Contaminants T & E species Infrastructure



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Data Collection and Surveying

DataDataCollection/Collection/

SurveyingSurveying


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Survey dam structure, longitudinal profile,cross sections, and sediment depths


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Survey long profile through impoundment;survey cross sections to capture change

Design Components: Data Collection/SurveyingDesign Components: Data Collection/Surveying


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Hydrology/Hydraulics

Hydrology/Hydrology/HydraulicsHydraulics

Wh h diff b h d l


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Whats the difference between hydrologyand hydraulics?

Hydraulics:

Depths and velocitiesof flows

Hydrology:

Magnitudes andprobabilities of flows

Design Components: Hydrology/HydraulicsDesign Components: Hydrology/Hydraulics

D d id


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Does your dam provideflood control?

Probably not

Flood Storage Potential:has storage volume and flow

through a controlled outlet

No Flood Storage Potential:

has full impoundment and

constant flow over spillway



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Whats a HEC-RAS and when do you need one?

Infrastructure protection

To prove fish passage

Post-project water levels for stakeholders

Advanced sediment transport modeling To address flood control?



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Sediment Management

SedimentSediment



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Some general sediment thoughts

Not all sediment movesNot all sediment movesNot all dams have a lot of sedimentNot all dams have a lot of sediment

Consider background yieldConsider background yield Sediment can be beneficial or harmfulSediment can be beneficial or harmful

Design Components: Sediment ManagementDesign Components: Sediment Management

Assess the quantity particle sizes quality and


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Assess the quantity, particle sizes, quality, andpotential mobility of impounded sediment

Potential mobilityPotential mobilityQualityQuality

QuantityQuantity Particle sizesParticle sizes



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The longitudinal profile is a fundamentalsediment analysis tool

Ox Pasture Brook Longitudinal Profile - 8/22/06

76.00

78.00

80.00

82.00

84.00

86.00

88.00

90.00

92.00

94.00

96.00

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0

Distance (ft)

Relative

Eleva

tion

(ft)

Sediment Surface

Water Surface

Bed Surface


T t di t f t i t d t


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Test sediment for contaminants and compare toecological and human risk thresholds

Complete due diligence

Assess quantity of sediment

Collect sediment cores (notgrabs)

Test for organics and heavymetals

Compare test concentrations

to human risk and ecologicalthresholds



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There are several approaches to managing cleansediment (depending on quantity and particle sizes)

Natural erosion

Sediment removal (dredging) Stabilize in place

Open dam gates

Remove dam slowly

Remove dam in stages

Combined approaches



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There are fewer approaches to managingcontaminated sediment

Management options

Remove and dispose Isolate and cap

If contaminant management is necessary,can greatly add to cost of project

Conundrum: dams are not goodhazardous waste containment facilities



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Protecting Infrastructure

ProtectingProtecting

InfrastructureInfrastructure

L k i d l i d t d i th d


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Look in and along impoundment and in the damfor at-risk bridges, retaining walls, or utilities

Design Components: Protecting InfrastructureDesign Components: Protecting Infrastructure


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Assess whether any infrastructure is at riskConsider if infrastructure can be moved first; next consider direct stabilization

Design Components: Protecting InfrastructureDesign Components: Protecting Infrastructure

Bridges Retainingwalls

Utilities

Species Protection and Additional


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Species Protection and AdditionalRestoration (beyond structure removal)

SpeciesSpecies

ProtectionProtection


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Identify if species of concern could beaffected by dam removal

Submit species info request to North Carolina

Natural Heritage Program (http://www.ncnhp.org/)

Design Components: Species ProtectionDesign Components: Species Protection

M f A i S i


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Manage for Aquatic Species

Monitor during constructionMonitor during constructionRelocate speciesRelocate species

Time the removalTime the removal Manage sedimentManage sediment

Design Components: Species ProtectionDesign Components: Species Protection


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Site-Specific Issues

SiteSite--SpecificSpecific

IssuesIssues


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Dam uses can oftenbe replaced

Design Components: SiteDesign Components: Site--Specific IssuesSpecific Issues


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Other site-specific issues:

well impacts, ice jams, parks, walkingtrails, renderings, etc.

Design Components: SiteDesign Components: Site--Specific IssuesSpecific Issues


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DataData

Collection/Collection/SurveyingSurveying

ProtectingProtectingInfrastructureInfrastructure

SpeciesSpeciesProtectionProtection

Hydrology/Hydrology/

HydraulicsHydraulics

SedimentSediment


SiteSite--SpecificSpecificIssuesIssues


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What will a dam removal cost?

The data set

225 total projects nationwide with cost data

median dam height is 9 feet

range 2 ft to 85 ft 92% were less than 25 ft

$77,582 median total project cost

in 2010 dollars

range $1,769 to $5.9 million

60 projects from PA

M di t t l j t t


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Median total project costs:

can be standardized by dam height

Dam Removal Costs


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Feasibility + Design + Permitting is25% of total project cost (median)

Dam Removal Costs

Wh t i it th t h


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What is it worth to havea streamlined process?

Dam Removal CostsDam Removal Costs


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Many funding sources exist

US Fish and Wildlife Service

National Oceanic and Atmospheric Administration

Natural Resources Conservation Service

State funds (Clean Water, DWR, EEP)

Corporate Donations

Private foundations

Funding for Dam RemovalFunding for Dam Removal


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Most funding hooks are environmental

Diadromous Fish Resident Species Listed Species

Funding for Dam RemovalFunding for Dam Removal

Who does the work?


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Who does the work?

Along with experience look for non-


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Along with experience, look for non-technical skills and integration of skills

Important non-technical skills:

Responsiveness and project

management Permitting

Presentation skills

Willingness to advocate forresource and project

No one firm is truly good

at all of these

Hiring Consultants

Integration of technical skills:

Engineering

Geomorphology Ecology

Traditional engineers may miss river context and habitat


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Hiring Consultants: Skill Integration

g y

Blend geomorphology ecology and engineering skills:


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Blend geomorphology, ecology, and engineering skills:

There are several approaches to


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There are several approaches toremoving a structure

Explosives Heavy Machinery By Hand

Fi l l d i h i d


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First, slowly drain the impoundment

Most commonly a backhoe with a hydraulic hammer will


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Most commonly a backhoe with a hydraulic hammer willbreach one side and then move across

Construction ApproachesConstruction Approaches


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Brian GraberBrian Graber

American RiversAmerican Rivers

[email protected]@americanrivers.org

Dam Removal Clearinghouse:Dam Removal Clearinghouse:http://www.lib.berkeley.edu/WRCA/damremoval/index.htmlhttp://www.lib.berkeley.edu/WRCA/damremoval/index.html

graber - dam removal project overview

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