Oroville Spillway Project May Soon Face another crisis? Unusual Weather Extreme of Heat? Affecting Repairs to Damaged Spillway?

In a Mirrored case of weather "extremes", the Southern Hemisphere may be giving insight into a possible "unpredictability" weather problem for the planning of the Oroville Spillway Repair "window". If this scenario plays out, California may soon, and unexpectedly, flip to another extreme of a sudden transition to Heat, or initially Heat with Rain.  This is a very dangerous combination for the damaged Oroville Spillway and Emergency Spillway given the current high snowpack levels in the Sierra Nevada mountains.

Highlights

By Tony Johnson
Catholic Online (https://www.catholic.org)
4/18/2017 (7 years ago)

Published in Green

Keywords: Oroville, Dam, Spillway, Failure, DWR, Extreme Heat, Flooding

LOS ANGELES, CA (California Network) - As Northern California has set an all time record for precipitation, including the snowpack in the Sierra Nevada mountains, (from Oct 2016 to Apr 13, 2017), extreme weather events were occurring in the Southern Hemisphere[2][3]. Record Rains & Extreme Heat (109 Fahrenheit for many days in Sydney Australia alone)  during our Fall & Winter, their Spring & Summer have been unexpected in "record" extremes. IF this relatively recent "bell weather" indicator follows (i.e. in the Southern Hemisphere & Northern Hemisphere) the expected moderation of Northern California weather & Western US may not be as expected. An example of this sudden change occurred in NSW Australia recently where they recorded the coldest February in a decade, while in the midst of an extreme Summer [1]. So unexpected were events that this unusual February included snowfall, from an unseasonal cold front out of the Southern Ocean. Shortly afterwards, in the same "summer", they immediately went back into their extreme heat wave. The hot summer created extreme fire danger - and resulting fires - over wide regions. Whether these conditions are reflecting a level of odd variance in the Northern & Southern Hemisphere "jet streams", the pattern matching of opposites is what's unusual.

The Oroville Spillway Repair project could ill afford an anomalous change in the expected weather moderation pattern entering into this spring and summer. If an unexpected variance develops such that the jet stream brings an unusual "heat" or "heat+rain" cycle excursion - in this typically moderate transition - the spillway would need to operate longer, thus pushing out the construction repair "window".  A dangerous combination could develop if the "heat" or "heat+rain" is swift and extreme as the damaged spillway may not be operable at safe levels above 40,000 cubic feet per second (cfs). It is very likely that the Independent Board Of Consultants may have determined that this current run rate of 40,000 cfs is a "safe margin" limitation due to the known design & construction defects in the current upper main spillway. 

A high volume snow melt-off, or rain/heat/snow melt flood scenario would force tough decisions to be made by the California Department of Water Resources (DWR), concerning the choice in elevating the main spillway cfs output flow, risking another blowout failure, while in combination with having to use the Emergency Spillway.   As the Emergency Spillway is known to have significant hillside erosion damage from its prior short operation, the near 1 million cubic yards of stored excavation material would be at risk as it is very close to the existing Emergency Spillway erosion channel to the Feather River.  Any extensive Emergency Spillway hillside erosion damage to the downslope hillside would widen this erosion channel and could threaten the massive stockpiles of this material.  The subsequent emergency cleanup of the river & erosion damage from any Emergency Spillway operation could close out any effective construction repair "window" opportunity for 2017, thus forcing a repeat of yet another major crisis.

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In Engineering Planning, contingencies must be planned and anticipated. These contingencies include the application in possible weather anomalies. DWR should detail their planning such that if any weather anomalies develop, they are not caught off guard in an un-recoverable position.

Fig 1. Northern California has set an all time record for precipitation, including the snowpack in the Sierra Nevada mountains, (from Oct 2016 to Apr 13, 2017), Graph NWS

Fig 2. SCS 61 Exceptional heat in southeast Australia in early 2017 Issued 22 February 2017, updated 24 February 2017

Fig 3. SCS 58 Record September rains continue wet period in much of Australia Issued 12 October 2016

More Reading:
[1] Australia 2017:  After heatwave, summer snow and coldest February in a decade.  Image: Summer snow - Mount Hotham on February 19, 2017. Credit: Hotham,  https://watchers.news/2017/02/21/summer-snow-victoria-nsw-australia-february-2017/
[2] Special Climate Statement 61 Exceptional heat in southeast Australia in early 2017 Issued 22 February 2017, updated 24 February 2017,  http://www.bom.gov.au/climate/current/statements/
[3] Special Climate Statement 58 Record September rains continue wet period in much of Australia Issued 12 October 2016,  http://www.bom.gov.au/climate/current/statements

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