Closer To Normal

This past Monday we began a slightly more typical week. There is a lot that needs to get done before the start of the “season”, and not much time to do it.

The big focus of this week is getting the systems in the OSL dialed in. Allow me to explain the basic outline of how the lab works:

This year, we have a new Sediment-Feeder. It is an auger that brings up sediment from the Sed Tank, which then spills into a funnel, accompanied by a jet of water to flush it down and into the stream

  1. We control how much water enters the head-box at the top of the section of stream. Water comes straight from the Mississippi, and we turn a large valve to determine the flow rate.
  2. At the same time, we adjust the rate at which sediment is fed into the stream system–which is also done at the head-box.
  3. Water+Sediment flows through stream.
  4. The sediment is dumped by the water into one of three bays in what is called the ‘tail-box’. The stream water flows down to rejoin the Mississippi.
  5. We move the sediment back to the top of the stream, after analyzing how much was deposited en-route.

This year, we have a new Sediment-Feeder. It consists of an auger that brings up sediment from the Sed Tank, which then spills it into a funnel, from whence it is flushed down with a jet of water.

The sediment gets shuttled up that white PVC pipe, and then dumped into the waiting funnel below.

Our sediment is stored in a huge 2,500 gallon tank that sits near the head-box. They are very particular about making sure that none of our sediment gets lost, which I can understand. The rod you can see to the left of the tank on the ground has a tape measure attached to it so that one can measure how much room is left in the tank:

The auger is driven by a motor, and thus the sediment feed-rate is determined by the motor speed. Unfortunately, I’ve been told that the current gear-box is inadequate, as we only end up running the motor at about 3hz, which apparently is bad (too slow) for motors. So, every once in a while the Sed Feeder gets jammed, and the auger stops spinning. In order to get the system going again, we’re supposed to just get this HUGE wrench and give a good rotational yank to the auger-shaft to try and unstick it. At first I was worried about doing this, thinking that perhaps something in it could get broken, but I no longer care. This whole system was designed and built by Dick, who works at SAFL. Pretty ingenious!

A lot of what we were doing early on this week was trying to figure out what we need to set the motor at in order to achieve the golden rate of sediment dispersal of 8L/2min.

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First Days

I met two fellow students I’d be working with over the summer, and had a fairly standard safety meeting. Then we got to work shoveling sediment. We (the research assistants) do a lot of sediment-moving.

However, after lunch we did not continue shoveling. Instead, we got a brief (thankfully) safety training on how to use an electric drill, were handed 350 buckets, and were told that each and every one needed 74 holes drilled in it by the end of the next day.  These buckets were to be used as tree-planters, and were specially designed. First, the bottom 3 inches of each bucket had been cut off with a table saw. Then, we were to cut slits up either side of the bucket so that the main top part could be fit into the bottom which had been cut off. Then we drilled holes through the part where they overlapped and zip-tied the bottoms to the tops. Finally, we drilled 8 columns of 8 holes each, for drainage.

Lotsa Buckets

These planters are to be placed in a large square basin (outside the OSL) which can be filled with water. In each planter will grow either Cottonwoods or Tamarix, in one of three different formations. The planters are there in order to keep the roots of each planted system distinct from the others, as these various plantings will be transplanted to the OSL after they have grown for a few months in order to study emergent vegetation in a stream setting–or at least this is what I have gathered. The Tamarix is actually a pretty interesting plant: it brings up salt, excretes it, and leaves (heh) it on the soil surface, which tends to kill other plants. It’s an invasive tree.

Eventually we finished the buckets. The cordless drills sucked, so we used ancient corded ones. Well, the batteries probably just weren’t used to being asked to drill ~26,000 holes in the span of 2 days.


Later in the week, the researchers arrived. They had shipped cross-country around 2,000 of both Tamarix and Cottonwood seedlings, carefully packaged in their lab. The Tamarix were shipped by UPS, and arrived on time. USPS was a day late with the Cottonwoods.

We put flags in those buckets that had a certain type of planting arrangement, in order to make counting easier.

That was the first week.

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Working at SAFL

This summer I have the good fortune to be working as a research assistant at the St. Anthony Falls Laboratory. I will be spending my time with the Outdoor StreamLab (OSL), which is an awesome facility.

The OSL is located on Hennepin Island, in the Mississippi River. Here is a panorama of the OSL that I stitched together using the freeware program Hugin. As you can see, there is a nice view of a cool stretch of Minneapolis riverfront.

View southwest over the OSL (click for zoom-able large size)

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