IMPORTANCE OF GEOLOGIC SETTING IN THE DEVELOPMENT OFIMPORTANCE OF GEOLOGIC SETTING IN THE DEVELOPMENT OFIMPORTANCE OF GEOLOGIC SETTING IN THE DEVELOPMENT OF OFFSHORE WIND PROJECTSOFFSHORE WIND PROJECTSOFFSHORE WIND PROJECTS

ALONG THE EAST COAST OF THE UNITED STATESALONG THE EAST COAST OF THE UNITED STATESALONG THE EAST COAST OF THE UNITED STATESDavid Krantz University of Toledo Toledo OHDavid Krantz, University of Toledo, Toledo, OHa d a t , U e s ty o o edo, o edo, O

J h M d d D Child U i it f D l N k DEJohn Madsen and Danny Childers University of Delaware Newark DEJohn Madsen and Danny Childers, University of Delaware, Newark, DE

Abstract Example of Importance of Geologic Setting Geologic Setting and PaleochannelsAbstract Example of Importance of Geologic Setting Geologic Setting and Paleochannels

In addition to first order considerations such as wind As an example the geologic setting of the Mid Atlantic portion During the most recent (approximately 20 thousand years ago)In addition to first-order considerations such as wind diti t d th i it t h id

As an example, the geologic setting of the Mid-Atlantic portionf th U it d St t t l i ill t t d Th k

During the most recent (approximately 20 thousand years ago),l l l t d l ti f th Mid Atl ticonditions, water depths, proximity to onshore grid of the United States coastal area is illustrated. The key sea level lowstand a large portion of the Mid-Atlantic

infrastructure, and ecological and human impacts, the geologic factor in determining the sediments that are found continental shelf was exposed as a land surface. Across thisg pgeologic setting must be considered in the location, and offshore in this region are the transgressive (in response to land surface, the Delaware River drainage system (as wellgeologic setting must be considered in the location, and construction of offshore wind sites The geologic setting is

g g ( pglobal sea level rise) and regressive (in response to global sea

, g y (as other major systems to the north and south) transportedconstruction, of offshore wind sites. The geologic setting is

relevant because it determines the sediments and rocks thatglobal sea level rise) and regressive (in response to global sea level fall) sequences that have formed during the Quaternary

as other major systems to the north and south) transported large quantities of sediments of all grain sizes Some of theserelevant because it determines the sediments and rocks that

t h ff h i d it / ill b l t dlevel fall) sequences that have formed during the QuaternaryP i d f l i ti (2 6 illi t t d )

large quantities of sediments of all grain sizes. Some of these di t f l i l i i ith i t di f thare present where offshore wind sites are/will be located. Period of geologic time (2.6 million years ago to present day). sediments were of glacial origin with ice extending as far south

A l l d ( i ) thas central Pennsylvania and southern New York and New

The coastal areas along the eastern seaboard of the United As sea level drops (regression), the England. The coastal areas along the eastern seaboard of the United States have evolved under conditions of global sea level rise coastline moves seaward. Additional

gStates have evolved under conditions of global sea level rise and fall during the past several hundred thousand years portions of the continental shelf areand fall during the past several hundred thousand years. D t thi l l ti th i d th

portions of the continental shelf are exposed Rivers extend across thisDue to this complex evolution there is a pronounced three- exposed. Rivers extend across this exposed land surface eroding materialdimensional variation in the types and distribution of exposed land surface eroding material

d t ti di t f thyp

sediments that occur at the surface and in the sub-bottom. and transporting sediments further sediments that occur at the surface and in the sub bottom. seaward on the continental shelf. Paleogeography

Given their different geotechnical properties the variableQuaternary Sea Level Curves

g g p yof the most recent

Given their different geotechnical properties, the variable di t ib ti f di t h i ifi t i li ti f i d A l l i (t i ) th tli

sea level lowstanddistribution of sediments has significant implications for wind As sea level rises (transgression), the coastline moves (Fletcher ,1990).

project sites, especially in the selection (e.g., monopile or landward. Exposed portions of the continental shelf are The Delaware River

p j p y ( g pgravity base), location, installation, and subsequent scouring

p pflooded by seawater. Former river valleys (paleochannels) are

The Delaware River channel shown on thegravity base), location, installation, and subsequent scouring

in the vicinity of wind turbine foundations Since foundationsflooded by seawater. Former river valleys (paleochannels) are infilled by marine sediments

channel shown on the continental shelf isin the vicinity of wind turbine foundations. Since foundations

are a significant component in the cost of developing aninfilled by marine sediments. continental shelf is

equivalent to theare a significant component in the cost of developing an ff h i d j t id tif i i th t b d th i

equivalent to the“Blue” paleochannel

offshore wind project, identifying regions that based on their p

shown below)sediment types allow for less complex geotechnical Chesapeake Bay

)yp p g

engineering solutions could have a significant impact on theengineering solutions could have a significant impact on the overall budget for an offshore wind project Delaware Bay New Jerseyoverall budget for an offshore wind project. y New Jersey

Th d i t l d d th l d f iA d l i i ti Wi d E A (WEA )

These drainage systems also eroded the land surface carvingAs developers examine existing Wind Energy Areas (WEAs) deep (up to 30-40 meter) channels as they flowed toward thealong the East Coast of the US, and as future locations for

p ( p ) ycoastline. During subsequent sea level rise, these “paleo”g

WEAs are defined by the Bureau of Ocean Energycoastline. During subsequent sea level rise, these paleochannels were infilled by sediments of marsh (organic-richWEAs are defined by the Bureau of Ocean Energy

Management Regulation and Enforcement (BOEMRE) thechannels were infilled by sediments of marsh (organic-richclays and silts) lagoonal (silts clays some sands) estuarineManagement, Regulation and Enforcement (BOEMRE), the

geologic setting should also be considered as a key factor inAtlantic Ocean clays and silts), lagoonal (silts, clays, some sands), estuarine

( ilt l d ) b h ( d ) t h ll igeologic setting should also be considered as a key factor in d t i i ti l it f ff h i d d l t

(silts, clays, some sands), beach (sands), to shallow marinedetermining optimal sites for offshore wind development. View of Portion of Mid-Atlantic Continental Margin of United States (sands to silts) origin. ( ) g

First‐Order Siting Factors and Geologic Setting Paleochannels and the Delaware WEAg g g

First-order considerations in the location, and construction, of , ,offshore wind projects include wind conditions, water depths,offshore wind projects include wind conditions, water depths, proximity to onshore grid infrastructure and ecological andproximity to onshore grid infrastructure, and ecological and human impactshuman impacts.

Ecological Impact e g A ianSeismic Reflection Profile 92-7 Crossing Delaware River “Blue” Paleochannel

(M h 1996)Ecological Impact – e.g., Avian (Murphy, 1996)

Offshore Wind Resource

Human Impact – e.g., Viewshed

Project Costs (e g F glsang and Thomsen 1998)Project Costs (e.g., Fuglsang and Thomsen, 1998)

Th l i tti i l t b it d t i thSeismic Reflection Profile 92-4 Crossing Delaware River

The geologic setting is relevant because it determines the g

“Blue” and “Orange” Paleochannels (Murphy, 1996)sediments and rocks that are present where offshore wind sites pare/will be located. Sediment types and their variation influence Variations in sediment type (e.g., clays, silts, sands, gravels)are/will be located. Sediment types and their variation influence the emplacement of offshore wind turbine foundations scour

yp ( g , y , , , g )controlled by locations (both horizontal and vertical) and infillthe emplacement of offshore wind turbine foundations, scour

protection devices cabling can dramatically impact costscontrolled by locations (both horizontal and vertical) and infillof paloechannelsprotection devices,cabling – can dramatically impact costs –

f d ti t t 20% f ti j tof paloechannels

foundations may cost up to 20% of entire project

Sediments and Geotechnical Considerations Siting Wind Turbines and Geologic Setting Offshore Wind Projects and Paleochannelsg g g j

Fine-grained deposits sensitive to compaction affecting Paleochannel systems areSub bottom sediments andg p p gbehavior and yield of turbines. Thick clayey units potential

Paleochannel systems areassociated with the major rivers

Sub-bottom sediments andth i t h i l tibehavior and yield of turbines. Thick clayey units potential

exclusion areasassociated with the major rivers occ rring along the Mid Atlantic

their geotechnical propertiesexclusion areas. occurring along the Mid-Atlantic

f Sare a major consideration in

H i t l d t l di b d i t d i icoast of the United States. The the selection of the type of

Horizontal and moment loading can be dominant drivers in sub-bottom sediments of all of the yp

wind turbine foundation (e gfoundation design, rather than vertical load. Ratio of horizontal currently designated WEAs are

wind turbine foundation (e.g.,monopile gravity baseg ,

to vertical loading higher than can be supported by friction alone.currently designated WEAs are controlled by the presence of

monopile, gravity base, ti i ) Thto vertical loading higher than can be supported by friction alone. controlled by the presence of

paleochannels The designsuction caisson). The

Avoidance of tensile stresses in soil is a significant design issuepaleochannels. The design

f ffpresence of paleochannels,

Avoidance of tensile stresses in soil is a significant design issue. parameters for offshore wind projectsand their associated variablein these WEAs, especially with regard infill sediments should be

Seabed sediment characteristics (e.g., grain size, mud content, , p y g

to foundation selection and cablinginfill sediments, should beconsidered in the siting of( g , g , ,

degree of cohesion) important parameters in seabed behaviorto foundation selection and cabling must take into account the variable

considered in the siting oft bi t ff hdegree of cohesion) important parameters in seabed behavior

during and after wind project construction (e g scour plumes)must take into account the variable nat re of the sediments associated ith these paleochannels

turbines at an offshoreduring and after wind project construction (e.g., scour, plumes) nature of the sediments associated with these paleochannels.wind project.

Questions? Contact John Madsen (jmadsen@udel edu)Questions? Contact John Madsen (jmadsen@udel.edu)