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$: Potential Impacts of Hydrofracturing on Dam & …...2013/01/29 · 1 BUILDING STRONG ® Fort Worth District SAGEEP, 29 March 2012 Potential Impacts of Hydrofracturing on Dam & Levee$
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Fort Worth District SAGEEP, 29 March 2012

Potential Impacts of Hydrofracturing on Dam & Levee Safety

Anita Branch, P.E. Senior Geotechnical Engineer Dam Safety Production Center, Tulsa ASTM D18.26 Committee Meeting 29 January 2013

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USACE Dam & Levee Safety Mission

ASTM D18.26 Committee Meeting

U. S. ARMY CORPS of ENGINEERS DAMS ...

694 Dams (USACE owned & operated) • Protect 15 million people • Provide $25B economic benefits / annually

Presenter

Presentation Notes

Just to give you a little background, let’s look at an overview of the Southwestern Division’s Dam and Levee Safety Mission. The SWD covers Texas, Arkansas, Oklahoma and parts of Kansas. Within the Division’s boundaries are 760 miles of levees and 90 dams. As you are no doubt aware, Corps dams were built primarily for the purpose of flood-risk management, however, the lakes impounded by those dams provide a substantial amount of water for the residents in three very thirsty states.

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U. S. ARMY CORPS of ENGINEERS LEVEES ...

USACE has oversight of approximately 10% of the Nation’s levees

• 2,500 Levee Systems (most locally owned/operated) • 14,500 miles of levees • 10M people protected • $120B damages prevented in 2011

Presenter

Presentation Notes


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Congressionally authorized purposes of these projects include:

• FLOOD RISK MANAGEMENT

• NAVIGATION

• HYDROPOWER

• WATER SUPPLY

• FISH and WILDLIFE CONSERVATION

• RECREATION

Presenter

Presentation Notes


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Benefits Provided by USACE Dams ... FLOOD RISK MANAGEMENT • Protect 15 million people • Prevent $236B direct damages • Provide $25B economic benefits / annually

NAVIGATION • 193 projects/293 chambers • 554M tons commodities moved (2011)

HYDROPOWER • USACE projects supply 24% of US electrical capacity

WATER SUPPLY • 329.2M acre-feet of water storage • 7,627 MGD (2009)

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Presentation Notes


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Benefits Provided by USACE Dams, continued ... FISH and WILDLIFE CONSERVATION • Threatened and endangered species • Environmental restoration/enhancement

RECREATION

Direct Benefits • 365 million recreation visitors every year • 112,000 private sector jobs • $3 billion in annual salaries

Associated Economic Activity • $16 billion a year • 270,000 private sector jobs

Presenter

Presentation Notes


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Dam & Levee Safety Implications of Hydrofracturing

ASCE Geo-Institute

Current USACE risk assessment is evaluating the potential impacts & risks associated with:

• Drilling • Injection • Extraction

• Hydrofracturing

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Presenter

Presentation Notes

When it comes to development of unconventional shales, hydrofracturing is usually what you hear about in the news. But hydrofracturing is only a piece of the process, and the Corps is evaluating each part of that process in order to determine how each phase contributes to potential project impacts and risk.

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Hydraulic Fracturing Risks ... INDUCED SEISMICITY • Oklahoma (Holland, 2011) • Bowland Shale, United Kingdom (de Pater, 2011)

TRANSMISSION OF FRACKING FLUIDS OUTSIDE TARGET ZONE VIA NATURAL FAULTS • Erosion of embankment in contact with faults could trigger failure

DISPOSAL OF FLOWBACK WATER • Potential for contamination of ground and surface water

Wells can be fractured multiple times, so project risk associated with frac’ing can occur over the life of the well …

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Presenter

Presentation Notes

Potential project risks associated with hydrofracturing are short-term, and they include Induced seismicity Transmission of fracking fluids outside the target zone Disposal of flowback water that comes back to the surface can result in contamination Additionally, since wells can be hydrofractured multiple times over the life of the well, the potential for problems is increased with each subsequent fracturing.

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POORLY CONTROLLED HYDROFRACTURING (“BREAKOUTS”) • Erosion of the embankment along existing faults located in the

foundation, abutments or outlet works could lead to project failure* *Failure defined as an uncontrolled loss of pool or flood storage INDUCED SEISMICITY • Consolidation of granular drains • Liquefaction • Stability • Cracking • Displacement

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Potential Failure Modes associated with Hydrofracturing ...

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Impacts to mission due to water demand: • water quality/storage/supply • navigation • low flow augmentation • environmental restoration • fish & wildlife enhancement • recreation • regulatory permitting

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Other Impacts on Congressionally Authorized Purposes ...

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ASTM D18.26 Committee Meeting 13

What do we need to include in this new standard for protection of dams & levees? How about nuclear power plants, bridges or other critical infrastructure?

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Require minimum offsets from critical infrastructure within which no HF allowed • Provide methodology for determining necessary offset distances, or • Specify absolute minimum offsets

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Require minimum offsets from critical infrastructure within which no HF allowed • Provide methodology for determining necessary offset distances, or • Specify absolute minimum offsets

Required rigorous evaluation of site geology

• From top of ground to bottom of target zone • Identify faults, fractures, water bearing zones • Obtain and test core samples of materials in each geologic unit • Estimates of physical properties (Young’s Modulus, Poisson’s ratio, permeability, density, etc) • 3D Micro-Seismic surveys for each HF event

Notification of any drilling and HF activities in close proximity to critical infrastructure

• Notification prior to start of activity • Provide map (ingress, egress, ponds/pits, tanks, • Where/how will waste products be disposed (solid and liquid) • Identify all parties and provide POCs • Identify dates of activities • Identify water source, quantity, chemicals, proppant • Identify HF pressures (average, max) • Well construction details (casing: material, wall thickness, location/limits; kickoff point,

cement details; survey location of toe/heel) • Identify site protection measures (erosion, spill prevention, etc)

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Dams and Levees are often many miles long Lots of different geology over those footprints Mitigation for HF impacts was not incorporated into project design Projects are only as strong as the weakest link

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This presentation does not represent any position or policy of the U.S. Army Corps of Engineers, nor does it imply any official endorsement of the information presented.

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Anita Branch, US Army Corps of Engineers Email: [email protected]

Life safety is paramount …

potential impacts of hydrofracturing on dam & …...2013/01/29 · 1 building strong ® fort...

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