September 14, 2012 – Resumed dredging after Hurricane Isaac

Dredge and Rainey Report
Resumed dredging after Hurricane Isaac

September 14, 2012

 

Summary of accomplishments:

  • Extended dredge hose along the bank
  • Dredged 5.25 hours into Cell 3 this week
  • Total time pumped directly into Cell 3 (.366 acres) = 25.25 hours
  • Total time in study cells = 171.75 hours

Impediments: water pump starting slow; tiny leak in a hydraulic hose

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

Tuesday, September 11

I arrived at the sanctuary in the 17-ft boat (the Avocet) at 9:30 and passed Timmy in the canal. He was on his way to the dock to meet some people from the NRCS that were coming out to Christian Marsh. I unloaded my gear at the house and reloaded the boat with dredge gear. I also picked up the section of hose that Timmy had repaired.

By 10:30, I was at the dredge site and went to the pond for my usual set of photographs. The water level was at 2 inches below marsh level, and the algae had bloomed to cover most of the surface, both mud and water, in Cell 3.

Figure 1. Algae covered most of the surface, whether mud or water, in Cell 3. This view is to the southeast from the dock, and the outfall is at the upper middle part of the frame.

Figure 1. Algae covered most of the surface, whether mud or water, in Cell 3. This view is to the southeast from the dock, and the outfall is at the upper middle part of the frame.

I had not had a chance to check salinities since the storm, so had brought the meter with me. Hurricane Isaac had pushed most of the water out of Vermilion Bay and our canals, and replaced the fresh water (3 ppm) with salt water (18 ppm). Today, even with low water, we had 6 ppm in the canal and 4 ppm in the pond. Wind and tidal action following the storm had allowed the fresh water from the Mermentau Basin to the west and the Atchafalaya Bay to the east restore the fresh/brackish regime to normal, at least at this end of the Sanctuary.

I unloaded the hose section from the boat and carried it to the present hose landing on the bank. With a cane knife, I cut a new path through the tall grass along the bank of the canal to extend the hose. The repaired section was connected to another unused section and pulled down the new trail. A hammer had to be used to disconnect the flex hose that went to the dredge via the canal, from the PVC hose that led across the levee to the outfall in the pond. The land section had been in place long enough to be covered by vegetation, and thick vines and brush had to be cleared away to move the existing hose into the new alignment. The extension was connected to this part, adding 40 feet along the bank.

To move the canal hose, I brought the boat around and pulled the end of flex hose onto the bow of my boat. I curled it over the bow to have a good length to roll back onto the new landing. With it tied securely in two places, I used the boat to pull the water-filled hose laying on the muddy, canal-bottom. The dredge had pulled the hose into a straight line, and I had to rearrange it to make it curve into the new landing closer to the dredge. It took two tries before I got it pulled in properly. To get it off the boat without it sliding back into the water, I had to tie it to a tree first. The free end was then pulled into place, hammered on and reconnected.

Figure 2. The hose was extended along the bank of the canal by 2 sections (40ft) of hose. The boat was used to pull the flexible hose in the canal along the bank to reconnect it.

Figure 2. The hose was extended along the bank of the canal by 2 sections (40ft) of hose. The boat was used to pull the flexible hose in the canal along the bank to reconnect it.

By 11:30 I successfully connected the hose at its new arrangement and went back to the dredge to cool off and take a break. As I was about to start the dredge up, Timmy arrived. He had finished with the NRCS guys early and was just in time to help dredge. However, I mentioned that I had lost a pair of wirecutters overboard last week when repairing the canopy, so before we moved the dredge, he went back to the house for a big magnet. He tied it onto a rope and pulled it around in the shallow water next to the dredge. It didn’t take very long before he felt the tool snap to the magnet, and it came up almost as shiny as it had gone under!

We had a bit of trouble getting the water pump started, but eventually prepped the dredge and engaged the pump at 1:30. When we went to swing the dredge over for the next drop of the
pump, the right traveling cable went slack. The cable had come loose from the rope tied to the anchor. I pulled up the cable to find the end, and Timmy jumped in the flatboat to reattach it. We settled back and started dredging. When we went to swing the dredge over for the next drop of the pump, the right traveling cable went slack – again. Rinse, repeat. The anchor had been moved back and the angle of pull was rather severe putting extra strain on the line, so we moved boats around and were very careful for the next few swings; and managed to dredge for almost 3.5 hours.

Our customary trip to the pond at the end of our day showed that we had created a star-shaped delta above marsh level, and the flow had pushed most of the floating algal mat to the northwest and west side of Cell 3. A number of peeps were reluctant to leave Cell 4 upon our approach, and settled back down as we wandered slowly along the walkways. We think they were Western and Least sandpipers, with a few Black-necked Stilts keeping them company. I also saw a small rail at the far edge of the marsh that disappeared as quickly as it appeared – I think it was a returning Sora.

Figure 3. The result of the days 3 hours of pumping had resulted in a star-shaped delta in Cell 3.

Figure 3. The result of the days 3 hours of pumping had resulted in a star-shaped delta in Cell 3.

Figure 4. A small flock of peeps were reluctant to leave the mudflat in Cell 4.

Figure 4. A small flock of peeps were reluctant to leave the mudflat in Cell 4.

Figure 5. Deer peas or 'hairy-pod cowpeas" (Vigna luteola) proved to be quite delicious!

Figure 5. Deer peas or 'hairy-pod cowpeas" (Vigna luteola) proved to be quite delicious!

On the way back to the boats, we spotted a large tangle of yellow-flowered, deer pea vines (Vigna luteola) which Timmy had been snacking on earlier. I have seen them in the marsh all my life and did not know they were edible, so we collected a container full.

We looked it up online where they were called “hairy-pod cowpea” and said to be related to black-eyed peas. I shelled them, cooked them up like any other dried bean with rice, and they were delicious!

Wednesday, September 12

As the sun rose above the horizon, I was struck by how far south it had already traveled. In June, it rose at the far left side of the backyard pond – now it was almost hidden behind the island again. I’ll be sad to see the days grow shorter, but I’ll also welcome the break from the heat. If only that meant a break from the mosquitoes!

Figure 6. The sun is well on its way to the south of our east horizon.

Figure 6. The sun is well on its way to the south of our east horizon.

Figure 7. A young male rufous (on the left) was in the mix of ruby-throated hummingbirds.

Figure 7. A young male rufous (on the left) was in the mix of ruby-throated hummingbirds.

The water was high in the canal and into the yard, and there were some scattered showers on the radar. We sat out on the porch to watch the hummingbirds while dodging a few scattered drizzles, waiting for the weather to clear. The aerial chases, wrestling matches and discussions were entertaining to say the least. We were able to identify a few of the humming hoard, and discovered 4 male ruby-throated hummingbirds, 3 female, 3 juvenile male; and 1 juvenile male rufous. I wasn’t aware that the rufous moved over/down so early, but with drought and fire in the west and Midwest, I wasn’t too surprised.

A rainbow broke out in front of us across the blue sky, and doubled at times. A killdeer performed an aerial display as it called loudly, up and down the canal, circling the house, and then rocketing into the sky. Downy and red-bellied woodpeckers clattered through the branches of the nearby live-oak tree. A large raccoon lumbered across the levee on the other side of the canal. Huge garfish rolled and splashed in the waterway at our feet. Life is good.

Figure 8. A killdeer rocketed into the sky in front of a rainbow.

Figure 8. A killdeer rocketed into the sky in front of a rainbow.

With a check of the radar, it was time to go to work. We were on the dredge by 9:00, but the water pump was slow to start. At 9:20 we started dredging with an overcast sky and 89°. I dredged while Timmy took a trip to the pond, and we pumped for about 2 hours before the right traveling cable broke. Instead of the rope slipping off, this time it was the rusted cable that broke right at the winch. We’ve been expecting this and had a stainless steel replacement ready back at the house. We were dredging again within an hour.

Everything was going well until I noticed tiny little bubbles that would appear at the surface of the water next to the dredge, and that would bloom into rainbow circles. We had a leak somewhere.

We stopped, hauled the pump up and washed it off, and discovered a tiny hole in the oldest hydraulic hose where it had originally been abraded by the metal deck grating. With the weather moving in and a hole in the hose, there would be no more dredging today. All of my work last week to neaten the hoses by cable ties had to be undone, and the problem hose was removed for repair.

We quickly went to the pond for end of the week assessment. The water level had come up to +2 inches above marsh level, and we had raised the outfall delta to at least +3” ML. The strange thing was that with all of our pumping, there seemed to be no sediment passing the containment on the west, and there was a plume of muddy water curling off to the east toward the marsh where we know of no outlets. This will be a mystery to be solved on another day. Rain clouds were quickly assembling in our area, so we packed up and returned to headquarters.

Figure 9. 5 hours of pumping today had raised the outfall delta to +3" above marsh level.

Figure 9. 5 hours of pumping today had raised the outfall delta to +3" above marsh level.

Figure 10. Rain clouds were moving in as we headed back to the Rainey headquarters.

Figure 10. Rain clouds were moving in as we headed back to the Rainey headquarters.

Back at the house, I quickly showered and packed up. With no dredging to do and plenty of time left in the day, I carefully interpreted weather patterns and dashed back to the public dock, chasing one rain system while being chased by another. I didn’t hit rain until I was safe and snug in my vehicle on the way back to Baton Rouge.

Figure 11. A weather front was coming fast behind me as I traversed Little Vermilion Bay to Intracoastal City, LA.

Figure 11. A weather front was coming fast behind me as I traversed Little Vermilion Bay to Intracoastal City, LA.

Figure 12. The estimated status of the study site as of September 12, 2012. Boardwalk and walkways are yellow lines, green lines are existing containment, the orange line is planned containment, outfall locations are shown as yellow crescents, white dots are PVC marker poles.

Figure 12. The estimated status of the study site as of September 12, 2012. Boardwalk and walkways are yellow lines, green lines are existing containment, the orange line is planned containment, 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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