MNDAK Upstream Coalition Charles Anderson, PE Water Resources - - PowerPoint PPT Presentation

MNDAK Upstream Coalition

Charles Anderson, PE Water Resources Expert Widseth Smith Nolting

• Southern inlet moved back north of

the Wild Rice/Red River confluence

• 20% distributed upstream retention

implemented as proposed by RRBC

• Did not require dams or staging area
• Began north of the Wild Rice/Red River confluence
• 30 square mile project
• Did not flood Oxbow, Hickson, Bakke, Comstock,

Wolverton or Richland/Wilkin Counties

• Preserved flood plain south of Wild Rice/Red River

Confluence leaving in place 100,000 acre feet natural water storage (flood plain)

100 Year Flood Plain (100 year event equals 42.5 flood in Fargo )

More than doubled the area from 30 square miles to 76 square miles Moved southern inlet 4 miles further south Over 50 square miles

• f current

plan is undeveloped flood plain

Area flooded in 2009 to be drained for Fargo’s development

Staging area covering nearly 80 square miles including:

• OHB
• Comstock
• Wolverton
• Richland County
• Wilkin County

Proposed Comstock Ring Dike Proposed Comstock Ring Dike

• Save $140,000,000 as no control

structure needed on Wild Rice

• Reduce staging elevations at OHB,

Comstock, and Richland/Wilkin Counties FM Diversion Authority rejected both FM Diversion Authority rejected both the VE – the VE – 3 proposal and the NWRR proposal and the NWRR alignment alignment

“Again, the ND alignment is a locally preferred alignment and therefore they chose the general location for the inlet. Their reasoning for the location of the inlet being further South than the MN alignment was to accommodate the city of Fargo's current future plans of development . . . “

Comments to Value Engineer Study, Appendix O, FEIS July 2011

“The non-federal sponsors did not request any further consideration be given to those combination plans considered in section 8.4.3 of this appendix, and all remaining combinations were dropped from further consideration.”

8.4.4 Phase 4 final Alternatives, FEIS July 2011

• Southern inlet to the diversion is moved back north
• f the Wild Rice/Red River Confluence; and
• 20% upstream distributed retention is

implemented? Anderson answered this question using the same Software/computer model used by the Army Corps and employed Army Corps assumptions: 100 year flood event = 42.5 feet in Fargo. (FEMA 100 year flood event = 39.5 feet)

Water level in staging area During a 42.5 foot Fargo flood event would be 915.58 (Current plan = 922.82) Elevation of flood water at Oxbow Hickson Bakke during a 42.5 Fargo flood event would be 916.15 (Current plan = 922.84) Peak flood elevation in Oxbow during 2009 flood = 916.48

With this combination:

• Fargo receives same level
• f protection
• O-H-B ring dike is

unnecessary

• Dam on Wild Rice River

is unnecessary

• Comstock and Wolverton

ring dikes unnecessary

• No impacts to Richland

and Wilkin Counties

• Entire Red River Basin

benefits – not just Fargo