Land Building Sediment Diversion at Myrtle Grove: Evolution & Status Update

Brian VosburgGeologistGovernor’s Advisory Commission MeetingAugust 1 2012

committed to our coastcommitted to our coast

Coastal Protection and Restoration Authority of Louisiana

• Re-cap of State/EDF Joint Myrtle Grove Investigation

• LCA Myrtle Grove Feasibility Study Status Update

• 2012 State Master Plan and the Myrtle Grove Diversion

• State Led Myrtle Grove/Mid-Barataria Diversion Engineering, Design and Permit Application Effort Overview

Presentation Overview

Coastal Protection and Restoration Authority of Louisiana

• Joint venture between CPRA & Environmental Defense Fund intended to provide the LCA Feasibility Study with robust decision making tools in the form of numerical hydrodynamic models based on site specific observational data

• Included site specific river data collection, riverside hydrodynamic modeling, and bayside hydrodynamic and land building modeling

• Seven Data collection events (2008-2011) at river discharges of 300,000 – 1,100,000 cfs

• Multi-dimensional river modeling of an array of diversion sizes, locations and alignments to identify optimal intake location and diversion configuration

• Bayside hydrodynamic modeling of water levels and velocities to evaluate impacts of different discharges and operating regimes

State/EDF Joint Myrtle Grove Investigation

MYRTLEGROVE

WATER DISCHARGE

P-6/63 Point Integrative Isokinetic Sampler

Spatial Trends(Bar Position)

Mg4 Mg3 Mg2b Mg2

May 15

May 14

May 13

May 12

May 11ADCP

Bar (sand) Resuspension

May 2010

662.8K cfs

726.4K cfs

Lateral Bar Face Suspended-Bedload

Cycle

THAL

WEG

LATERAL BAR

Bedf

orm

s

RH

Water Vel.

Water Vel.

Water Vel.

Myrtle Grove Diversion

FLOW-3D Model Domain

Coastal Protection and Restoration Authority of Louisiana

• FCSA executed and Study initiated May 2010- √

• Develop and Screen Initial Measures August 2011 - √

• Hydrodynamic Modeling (Barataria Bay water level and salinity) February 2013*

• Identify Tentatively Selected Plan May 2013

• Chief’s Report signed October 2014

LCA Myrtle Grove Feasibility Study

Coastal Protection and Restoration Authority of Louisiana

• Identified 8 Diversion Projects, including one in the vicinity of Myrtle Grove-

• “Mid-Barataria Sediment Diversion”• 50,000-250,000 cfs sediment diversion in the vicinity of Myrtle

Grove intended to maintain existing land and build new land• Two phases- initial 50,000 cfs magnitude, then increase to larger

250,000 cfs magnitude sometime in the future

2012 State Master Plan & Myrtle Grove

Keystone of the 2012 Master Plan: Reconnecting the River

Flow regimes of sediment diversions based on flow in river. Large-scale diversions (250,000 cfs) operate at full capacity for short periods of time (typically less than a

month) and in some years, are not operated at all at full capacity.

Uses up to 50% of the Mississippi River’s peak flow.

Coastal Protection and Restoration Authority of Louisiana

• The State is currently in the process of seeking a Contracting Firm that will manage the complete process of engineering and design, environmental compliance, and permit application for a ~50,000 cfs magnitude Diversion in the vicinity of Myrtle Grove. (Mid-Barataria Sediment Diversion)

State Led Engineering, Design and Permit Effort

Coastal Protection and Restoration Authority of Louisiana

• A sediment diversion at this location is a top priority for the State.

• The LCA Myrtle Grove Study will continue, and will communicate and coordinate with this effort.

• Provides a Parallel Path for the LCA Myrtle Grove Diversion and the State Master Plan Mid-Barataria Diversion.

• Goal is to ensure that the State is well prepared to act should sufficient funding become available to implement the project, particularly if the funding becomes available relatively soon.

• The “parallel path” approach will best position the State to implement this important project should funding become available from any source.

State Led Engineering, Design and Permit Effort

Coastal Protection and Restoration Authority of Louisiana

• Key Milestone Dates (tentative)

• Mid-August 2012 – Selection of Contracting Firm

• Mid-October 2012 – Issuance of NTP

• Mid-October 2013 – Submittal of Permit Application

• Mid-April 2014 – Submittal of Final Design with bid Documents

State Led Engineering, Design and Permit Effort