September 7, 2012 – Post-Hurricane Isaac

Dredge and Rainey Report
Post-Hurricane Isaac
September 7, 2012

Summary of accomplishments:

Moved dredge back into position
No pumping this week

Impediments: high water

Hurricane Isaac made landfall on August 29 and 30th in south Louisiana. Rainey was extremely fortunate to be on the west side of the storm, with little rain and wind, and water levels lowered instead of rising with the feared storm surge. Timmy was able to return to the property by that Thursday afternoon as the storm moved past Baton Rouge, a hundred miles to the east. The headquarters never lost power, and suffered no significant damage. The lowered water level drained the freshwater (3 ppm) out of our canals and replaced it with more saline water (18 ppm) when water levels returned to normal. On the dredge, only one canopy cable came loose as a result of the storm. All items removed from the house in the evacuation were replaced by Labor Day (the following weekend).

This report can be downloaded in PDF file format by clicking the Dredge and Rainey Report, Post-Hurricane Isaac hyperlink.

Thursday, September 6

Timmy picked me up the evening before so I wouldn’t have to bring the other boat. The morning dawned clear as we loaded up the flat boat with all of the equipment and items removed from the dredge. By 7:30, we had both the flat boat and the Goose on the way to the dead-end canal where the dredge was tied for the hurricane.

Figure 1. With a clear morning, we loaded all the dredge paraphernalia into the flatboat.

Figure 1. With a clear morning, we loaded all the dredge paraphernalia into the flatboat.

I unloaded the gear from the flat boat onto the dredge, then picked Timmy up from the Goosethat he had tied to the bank. While Timmy used the flatboat to access the bank and untie our safety lines, I worked the winches; and assessed the storm damage to the little dredge. This proved to be only the broken cable that holds the canopy on one side. Some of the PVC ribs had come loose and fortunately landed on the deck.

Figure 2. Timmy towing the dredge backwards from its storm haven to the dredge site.
Figure 2. Timmy towing the dredge backwards from its storm haven to the dredge site.

We pulled in all lines and hoisted the spuds out of the mud. Timmy used the flatboat to maneuver the dredge away from the bank, and decided to keep towing instead of going back for the Goose. Last week when we had used the bigger boat to bring the dredge to safety, the wind kept grabbing both boats and made maneuvering difficult. This time, Timmy towed the dredge with the flat boat – backwards – and found it much easier to keep them online. It was a slow mile, but gave me time to get a new cable cut to replace the broken one, with time to spare to enjoy the cruise.

By 9:00 the dredge was back in position. Timmy used the flatboat to reposition the traveling cables, while I stayed on the dredge to operate the winches and drop the spuds. When everything was secured, I took him back to the Goose, and he went back to the house to get the mower.

Figure 3. The sprigs of marsh planted next to the boardwalk at our test site was now 5 feet wide.

Figure 3. The sprigs of marsh planted next to the boardwalk at our test site was now 5 feet wide.

The test site was on my way back to the dredge, so I stopped to assess storm damage and found none. Instead, I found that the smooth cordgrass (Spartina alterniflora) that was planted next to the boardwalk in sprigs almost a year ago was now a dense 5-ft band of solid marsh. The test site was where we had practiced dredging back in the fall of 2010 before moving to the current study site.

Timmy still wasn’t back with the mower – he planned to mow elsewhere first, so I stopped to assess the study site as well. The water level in the pond was at 4” below marsh level, exposing the fill at the south end of Cell 3, which was now being covered with bright green algae.

The low water let me get a good look at the results of the cumulative 17 hours of dredging into Cell 3 (see figure 11). At the south end, the substrate level was 3 inches higher in Cell 3 than the water level in Cell 2 across containment 3b. This meant that there was a good 5-6 inches difference in the substrate levels. With a marker pole in a fortuitous location, the deltas formed at the point of outfall proved to be at least marsh level or an inch above.

Figure 4. The view to the southeast of Cell 3 from the dock showed exposed fill covered by bright green algae.

Figure 4. The view to the southeast of Cell 3 from the dock showed exposed fill covered by bright green algae.

Figure 5. The containment 3b separates Cell 3 (left) from Cell 2 (right), and showed a difference of 5 inches in substrate elevation. The mudflat of Cell 4 is in the background crossed by walkways.

Figure 5. The containment 3b separates Cell 3 (left) from Cell 2 (right), and showed a difference of 5 inches in substrate elevation. The mudflat of Cell 4 is in the background crossed by walkways.

Figure 6. The right cable holding the canopy had to be replaced and the PVC ribs were put back into position.

Figure 6. The right cable holding the canopy had to be replaced and the PVC ribs were put back into position.

Back at the dredge, I worked to repair the canopy. The support cable was supposed to be connected to and stretched between the A-frame at each end of the dredge. To replace it involved untying the fore and aft corners of the canopy, threading the new cable through the poles and tie-downs, stripping the old cable out, installing cable clamps, tightening the turnbuckle, replacing the PVC ribs that had come loose, and retying the corners. Working up and down a ladder and overhead was tiring. Timmy came and mowed before I was done.

He then helped me unstrap the pump from the deck where we had secured it during transport, return it to its upright position, and connect all the hoses. We had hoped that the water level would come up while we were completing these tasks, but were disappointed. With the water level so low, we were afraid that the head pressure created by pumping into the contained cell would cause scour under the containment which would nullify any dredge effort. We shut everything down and returned to headquarters.

Friday, September 7

Water level was still too high in the pond to dredge, so we enjoyed a leisurely, pre-autumn morning birdwatching off the front porch. We had about 9 early hummers at the two feeders off the front porch, saw western kingbirds and female Baltimore orioles in the trees across the canal, downy and red-bellied woodpeckers in the oak trees, and heard white-eyed vireos in the bushes.

Figure 7. Early morning birdwatching included hummingbirds, western kingbirds, and baltimore orioles.

Figure 7. Early morning birdwatching included hummingbirds, western kingbirds, and baltimore orioles.

Around 9:00, we decided to rake a trip down to the Gulf beach to assess storm damage. The 4-wheeler was loaded into the Goose and unloaded at Chenier au Tigre. Mosquitoes and deer flies were terrible for the entire land trip.

The Gulf beach was lined by a wide band of wrack made up of dead water hyacinth and other debris, some from the Atchafalaya and some from the Gulf. Feral hogs had rooted along the entire length of beach below a storm-carved scarp that was a foot and a half high. The storm had removed some of the subaerial sandspits that connected the breakwaters to the points on the shore. We discovered the neighbor’s wild-cattle were out on the beach trying to escape the bugs.

Figure 8. The wide wrack line was rooted by hogs for its entire length along the beach.

Figure 8. The wide wrack line was rooted by hogs for its entire length along the beach.

Figure 9. Some of the sand spits that connected the breakwaters to the shore were removed by Hurricane Isaac generated currents.

Figure 9. Some of the sand spits that connected the breakwaters to the shore were removed by Hurricane Isaac generated currents.

On our way back along the shore, we did a bit of beach clean-up by collecting useful lengths of rope, a pipe, boat seat, buckets, and found a float that we think will serve nicely on the dredge hose outfall. The water level remained low, so with no dredging possible today, I packed up and Timmy took me back to the dock for my return to Baton Rouge.

Figure 10. Wild cattle were on the beach and in the water to escape the irritating insects.

Figure 10. Wild cattle were on the beach and in the water to escape the irritating insects.

Figure 11. The estimated status of the study cells as of the end of August. Boardwalk and walkways are yellow lines, containment are green lines, planned containment is the orange line, outfall locations are shown as yellow crescents, white dots are PVC marker poles.

Figure 11. The estimated status of the study cells as of the end of August. Boardwalk and walkways are yellow lines, containment are green lines, planned containment is the orange line, outfall locations are shown as yellow crescents, white dots are PVC marker poles.

 
Karen A Westphal and Timmy J Vincent, National Audubon Society
Louisiana Coastal Initiative and the Paul J Rainey Wildlife Refuge
6160 Perkins Road, Suite 215, Baton Rouge, LA 70808
225-768-0921 office, kwestphal@audubon.org
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