[brcs-announce] Steve Alrgent's Update about the BB dam

[Norman R. Fred]

Saturday (10-13-12) - It's been a long week for the many people involved or
directly impacted by the sudden breech of Brown Bridge Dam a week ago today.
It's been a particularly long week for the property owners that received
flood damage.   Molon and AMEC staff along with their insurance adjusters,
MDEQ staff and numerous others have spent the week inspecting the drawdown
structure trying to determine what went wrong.   It's hard to say when we'll
know exactly what happened but it appears that there is some debris in the
area of the dewatering structure, including old sheet pile, from when the
dam was constructed nearly 100 years ago.  Whether this debris had any
effect on the dewatering structure is yet to be determined by investigators.

During the past week Molon crews finished clearing debris from public and
private bridges.  AMEC brought in engineers that inspected every public and
private bridge for damage.  The most urgent crossings to be inspected and
opened back up to traffic were the Garfield Road and River Road crossings.
Everything checked out ok and the roads were opened back up to traffic by
Monday afternoon.   The engineers also inspected the private bridges and
only found a couple that received major damage from the event.  One bridge
was actually taken out by the flood.  

The river took a major hit but appears to have handled the floodwater fairly
well.  During the past week AMEC, MDEQ staff and others have been collecting
biological data and mapping the extent of the high water.  Biologists have
collected nearly 300 dead fish, approximately 85% warm water species from
the pond.  MDEQ biologists also collected aquatic insects at various
locations downstream of the dam.  Closer to the dam they found both river
and pond species.  The river species including mayflies, stoneflies, and
caddis flies were found in decent numbers and diversity which means the
river wasn't wiped out from an insect standpoint and the food base will
recover quickly.    Within the pond itself by Sunday it was too late to
rescue the warm water fish including bass, blue gill, pike, bass, perch and
suckers that were stranded on the bottomlands.  Eagles, heron, otters, sea
gulls and other animals have been feasting on the remains all week.  A work
crew from the Grand Traverse Band spent the better part of two days
collecting turtles that were released back into nearby lakes and marshes.
These were mostly snappers and painted turtles.  

The main concern right now is how cloudy the water continues to flow. This
is from the fine organic material (silt) that's still in the small
backwaters of the remaining pond.  Molon crews constructed a rock weir
approximately five foot high just above the dewatering structure once they
had the breech under control.  They did this in an attempt to capture any
sediment they could.  This silt is staying in suspension and flowing over
the rock weir.  At the east end of the project in the sand delta area the
sand traps held and effectively stopped any major head cutting upstream.
Molon continues to clean out these traps on a daily basis.  Biologists are
determining the best way to proceed given the current situation.    

I said it before and I'll say it again it could have been much, much worse.
Had Molon crews backed up by Elmers trucks and other equipment not been able
to control the breech, a wall of water at least twice the estimated 5-foot
crest that did occur would have swamped the valley possibly taking out roads
and causing much more property damage and who now what else.   I asked Pat
Cole, owner of Brady's Bar who has a place on the river how his place faired
and he said "the river came up 5 feet and my place sits at 8-feet so it was
close but ok".   I know many other property owners that came back or waited
out the flood reported a similar close call..I also know many weren't as
fortunate.  It those folks I feel the most badly for.  

I'd like to thank John Russell from Great Lakes Images for the great pics
from a Coast Guard helicopter from the day of the breech.    Please call me
if you have any questions.  Thanks.  S.

Steve Largent
Boardman River Program Coordinator
Grand Traverse Conservation District
231.941.0960 Ext - 16
231.883.9960              
Your message is ready to be sent with the following file or link
attachments:

Mike Walton and Al McDonald inspect dewatering struture.  The sheet pile
near the back of the boat is from when the dam was constructed over 90 years
ago.
Pete Prouty shows the high water at his house
Pulling the first sheet pile in-front of  the dewatering structure
Rock weir to help capture remaining sediment.
20121006 245
20121006 287
After over 90 years the new river flows in its old channel once again.
Breech begins inside dewatering structure approximately 20 minutes after
first sheet is pulled
Clearing debris from public road crossings

Keeping the posting of pictures up to date has been a problem for us - 


Look for pictures on this site from now on:

http://www.flickr.com/photos/nature_is_calling/sets/72157631744898788/


NOTE from Steve via the line line:  The pictures I attached to this email are NOT on the Flicker site yet.  They will be posted - hopefully - on Monday.


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