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 )

Over 50 More than square miles doubled the of current area from 30 plan is square miles undeveloped to 76 square flood plain miles Moved southern inlet 4 miles further south

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 of 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 of 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