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And when I was really little, I heard somebody talk about the river beneath the

2020-02-03

Missouri River and I kind of wondered what that was all about. My imagination jumped to an underground cave going down, well this is a picture of one of the underground rivers in the Yucatan Peninsula. Brad Higgins, my associate, has swam and kayaked through some of these underground rivers. Really a neat trip if you ever get down there. But that's not the river underneath the Missouri River. Really the river beneath the Missouri River is water that flows around sand and gravel particles that comprise the alluvium of the water deposited materials in the Missouri River Valley. So the very small streams of water, if you will, flowing around all the particles, is actually the river beneath the Missouri River. Let's start out looking out kind of a map of the floodplain. This is from Brian Kelley's USGS report in the area. We see the width of the Missouri River Valley, this area a little less than 4 miles wide in the Kansas City area, 2 to 2-1/2 miles wide, much wider over in the Ray County area, and one little interesting thing to note about this, you see this little alluvium, the river alluvium coming down This is the Lake City area, Independence, Lake City, Buckner area. And what happened is, the glacier, last glacier, came down and actually just formed this location, to the southernmost extent of the glaciation. However, right in this area, the glacier came back a little bit and blocked the river and caused the river to spill over to the south and come back this way. Note also how narrow the river is compared to the floodplain. We not only have the core of engineers to thank for making that narrower, but also we have much less reduced surface water flow since the time of the glaciers. So there is comparatively speaking, smaller flows in the river now than at the time the glaciers were coming down. If we look at a cross section of the river valley, we have bedrock, big bedrock ditch or trough that's filled with sand and gravel and down at the bottom will be boulders, cobbles, large unbelievably large rock grating up with finer sand, silt, and clays at the top. How did this get carved out of the bedrock Imagine 10,000 years ago when the glaciers were coming down. In the winter time, move down, in the summertime there would be a tremendous amount of melt water. Tremendous really torrents of melt water moving large boulders, gravel, just cutting out the bedrock and then as the water receded, it would leave the boulders, the sand, and the silt and gravel at the time. This is a map from Brian Kelley's study. The darker spots are the deepest part of the aquifer. And you can see right through here, the aquifer is really fairly deep, in some places 120 to 150 feet deep. Most of it is in the neighborhood of 80 to 100 feet, but there is a deep hidden valley, deep buried valley that contains boulders, cobbles. It is extensive. Now how much water is contained in the alluvium The sand and gravel, water deposited materials is caused the alluvium, so how much water is in it If we drain one cubit meter or one cubic volume of saturated aquifer, how much water would we get out Or if it was dry, how much would we put in So we have a little experiment here. I have one liter of dry sand. It's kind of a medium grade sand. And we have a graduated cylinder and I'll ask Janie to pour water in slowly and see how much that takes until we completely saturate the sand. And right now, we've added 200 milliliters, and it is still taking more water and that will soak in. We've added 250 milliliters, which is 25% of the volume of this sand. And it will actually take a little bit more. So it's still dry. So if we look at a volume of saturated sand, we can get 15 to 30% of that is pore space filled with water. We can drain that water out with wells for our use. How much water is in the alluvium itself Well the one cross section that we had, the sands and gravel let's just say is averaging 70 feet thick and some places deeper, some places a little shallower, and a little less than 4 miles wide at this particular section. Now if we take a length of the river valley in the river, say not one mile, not a half a mile, but if we had just a one foot thick slice of the alluvium across the complete valley, contained within that slice, one-foot thick slice is over 2 billion gallons of water. And that's enough for 12 families, to serve 12 families for one year. And that's just a one foot slice of the aquifer thickness all the way across the valley. So if we look in the Kansas City area for say a mile length of the river and the valley, within the alluvium, there's about 15 times, 15 to 16 times more water in the alluvium than there is in the river. Granted, the water is flowing a little slower through the sand and gravel than in the river. In the river we might talk about feet per second, or miles per hour. In the aquifer we're maybe talking a foot per day, a little less, a little more, the speed or velocity of flow. Now let's get into the mechanics of what's going on just a little bit. When no runoff is contained, ground water will flow toward the river. Water flows from higher elevations to lower elevations, so due to infiltration, rainfall infiltration, the water table has built in this area, and the water will flow to the river. When there is no surface runoff, that's called base flow. The river is really just a drain for the aquifer. Looking at this diagram in another way, here again we have high water levels due to infiltration, so water is moving from higher elevation to lower elevation. It's moving to the river and into the river. Again, the river is a drain for the aquifer. However, during floods, when water levels are up, or due to excessive pumping and the water table has been lowered, the water again will move from higher elevation to lower elevation. It will move from the river into the aquifer, so it can go either way. There is a connection between the aquifer and the river. Looking at a hydrograph, a chart of water level elevations with time, the black line is the stage or elevation of the river. The black line goes way up. There is a difference in river elevation here. From this point, this high point to the low point, that's about 20 foot elevation, river elevation change. Now as you see, we have this flood or high rise in the river level. Right in here you can see the groundwater level. I'm sorry, these are monitoring wells installed in the alluvium some distance from the river, varying distance, but as the river comes up the levels in the monitoring wells will change also. And you can see the monitoring well level kicking up as the river goes up and then as the river recedes, flow is less, groundwater levels in the monitoring well follow the river, and so there is about a 10 foot difference between ground water levels, due to the change in the river level at this particular point. These are wells installed close to Boonville, between Boonville and Rocheport, in the Missouri River alluvium. And back to our friend again, the base flow diagram. Again the precipitation fall infiltrate to the water table and then flow from higher elevation to lower elevation and recharge the river. Now, if we install a well and start pumping, and if the well is somewhat, some distance from the river, or the quantities are not too high, what we are pumping out is 100% groundwater. It's water that's being intercepted on its way to the river. So we're removing some of that water, intercepting some of that water. If the well is close to the river or pumping large quantities of water, the gradient is reversed and again water is flowing from high elevations to low elevations, and high elevations to low elevations. What we're doing is inducing water flow from the river through the river bed to the well. It's called induced infiltration. Now this characteristic is very useful because in the river we know that there is a lot of sediment. It is dirty, a lot of silt, sand. There are pathogens and sometimes there are some organic toxins and by filtering through the river bed, the sediment is removed, most of the pathogens are removed and a good part of the organic toxins can be removed as they attack to the clays and silts in the river bed. And this is used fairly extensively in Europe, especially Germany, along the Rhine and some of the other rivers that are heavily polluted. This is considered the first step of their treatment process. With all this magic of all this water underground, how do we get it out and how do we use it We construct a well and the basic schematic for a well in the alluvium, and we generally call these shallow wells. They may be 150 foot deep as compared to deep as compared to deep wells that we have in the bedrock say in the Ozarks that might be 1500 feet deep. So there are pretty shallow, but they can be very large capacity wells. And the general schematic is that we drill a bore through the alluvium through the aquifer and then install a casing with a screen at the bottom to let the water in, and then we fill the annulus of the hole with a very select gravel to hold back or stabilize the aquifer materials while allowing the water to flow into the well, and then we seal the top of it with a grout to prevent contaminate surface water from moving down. Then after this is complete, they will install a pump inside to pump the water out for our use. Now the way they used to drill wells, and they still do some wells this way, the old-fashioned way is what they call direct rotary drilling. They pump water down through the drill steel and then a drill bit will disturb the materials or cut the materials and then the water will carry the sediment to the surface. Well as the borehole gets bigger, we still have the same velocity of water coming down, but because of the much increased diameter of the bore, the upward velocity gets very slow and won't carry the sediments. So they do things like thickening the fluid to allow the fluid to carry the sediments out. The problem with that is that thick mud that carries the sediments out, gets into the formation and actually blocks the flow of water into the well. Some years ago, somebody developed a new method that's much more efficient called reverse rotary drilling, where the water flows down the annulus, the bit disturbs the material, and then the water is pumped at high velocity up through the drill steel, which can be 6 to 8 inches in diameter, so large sediment can be carried up and out of the borehole with that. This is a setup for a well getting ready to be drilled. This is the mud pit, if you will. It continues around this end. They will fill this with water. The water will flow around through a pipe into the well bore. The drill pump and bit will bring the water up through here and discharge it back in here where all the sediment will drop out and then water can circulate back around. This is a picture of a well being drilled for Kansas City. It's kind of a messy operation, especially in the wintertime. In the wintertime, it gets chilly. This is a picture of a drill bit, a couple of drill bits, in the sediments. They just use something like this, it's pretty basic. They just disturb the sediments, the sand and gravel, and then it's sucked up this pipe. Now when they get down into the cobbles or limestone boulders, they'll use this rotary type bit to break that up. This is a typical sample of sediments that we will catch during the drilling process, and we will run a size analysis on this material so that we can design the gravel pack to stabilize the bore and there is a picture of some select gravel that has been sized specifically for that particular well and then the well screen to hold the gravel pack. This is a sample of some the gravel pack with it, how it relates to the screen size. A couple of pictures of well screens. This is a 70 slot or 70,000nds of an inch gap in well screen to allow the water in. Here they are getting ready to run the screen into the well. You can tell some of these screens are fairly large. We have installed 36 inch diameter screens for some of the Kansas City wells. They have to weld these strings together. There may be 60 or 80 feet of well screen in each well, and for the reverse rotary drilling, you can't stop. If you stop you have a chance of the hole collapsing and losing the hole. So its a 24-hour a day operation after it gets started. Here they are using a hopper to feed gravel pack into the well bore, and then when they're finished, this is one of the typical instillations. This is for Kansas City, Missouri. They will install a casing on a crow's nest for the motor, for the pump motor, and they will size this above the expected flood levels. They'll install the pump, which is down in the ground, the motor is up at the top, and then the discharge is underground. This particular well goes about 140 feet deep and it's atypical for the area. We can pump about 4,000 gallons a minute from this well. You think of your garden hose, running your garden hose, you may have about 2 or 3 gallons a minute, maybe. This is rated at 4,000 gallons a minute, so that would take a pretty big hose for that. There are numbers of cities in this area that use groundwater for their water supply. Independence, Parkville, Johnson County Water District, Kansas BPU, just numbers of cities that use groundwater for their water supply. This shows the location of the Kansas City well field, and that big well is located fairly close to the center of the valley in the really deep buried valley section. There are other wells that are a little bit shallower and only rated for about 1,000 gallons a minute. Kansas City has a surface water intake that they get most of their water from. I believe the plant is rated for something like 300 million gallons a day, in that neighborhood. So why does Kansas City, with the surface intake, want wells Well they use the groundwater, the alluvial groundwater in a fairly unique manner. I don't remember their total groundwater supply. It may be 30 million gallons a day, I'm not quite sure. But they use it to solve several problems. Using river water, there are 3 significant problems: The temperature of the river ranges from in the summer from 80 degrees to winter to 32 degrees. That change in temperature really causes some real significant problems. First is that cold water takes a lot more chemical to treat. So when it's really cold, they have to spend a lot more money for treatment. Secondly, when it's freezing, the treatment basins freeze, causing operational problems. And then biggie is our ancient water lines. The thermal differences cause thermal expansion in those old water lines and when the water temperatures drop, we start having water main breaks. So the city uses these wells to pump warm groundwater out when the river temperature gets down to a certain point, they'll pump warm groundwater to moderate that cold water temperature. Again it's the induced infiltration, they'll start pumping the water out, the warm water out, but as they do that, cold water starts moving in. So if they turn the wells on too soon, or if it is a very long cold winter, they could run out of warm water. And then in the summertime, they pump the cold water back out, drawing warm water in from the river to resupply their bank deposit of thermal energy. Well there's another type of well that's become popular and I've worked on quite a few in the region, called a horizontal collector well, and they're called horizontal collector wells because of the horizontal laterals that are projected out under the river and along the river, that consists of a concrete caisson that extends down to bedrock or a couple hundred feet, or a hundred feet or so. The laterals are then pushed out and then after that's done, they build a pump house on top of the wells, pumps, they build a pump house on top and install pumps to pump the water out for our water supply. Construction is kind of interesting. They cast the cylinder. The first cylinder may be about 12 foot high piece of cylinder, then they use a clamshell and they just dig the sediment out from below it and then it starts sinking under its own weight. When this gets down to ground level they'll cast another section of concrete right on top and then clamshell out the middle and it will just sink right on down. When they get to the bottom, they will put a seal in the bottom and then they push the laterals out in sort of a unique way. This is a blank casing with kind of a digging head, what they call a digging head with holes in it in the front, and then they have a smaller diameter pipe coming in the middle. The hydrostatic pressure pushes water at high velocity through these holes in front of the digging head, and so it is moving the sediment, the high velocity is carrying the sediment with it into the caisson itself while big jacks push the lateral out. Here is a picture of that operation. The blank casing, the sand pipe, and then a jack pushing that out. After that's out to about 200 feet, they'll install well screen just like this one inside that blank casing and then pull back the blank casing to expose the screen to the sediments. They may have 5 or 6 of these laterals 200 feet long. That may be 1,000 or maybe 1,200 feet of screen with a lot of open area that lets a lot of water in, so there's a lot of water that can be developed with these collector wells, versus a vertical well with maybe 50 feet of screen. So you can see there is quite a difference in the capacity of these wells, and then when it is finished, a pump house with pumps. We have several in our area, these collector wells. This is Kansas City, Kansas Board of Public Utilities. This well can pump over 40 million gallons a day and it's rated as the largest capacity well in the world. Kansas is pretty lucky, they have the deepest, or the biggest hand dug well, and they have the biggest capacity well. BPU has since installed another one of these, fairly large adjacent to it. This is over in the Parkville area. Johnson County Water District One has installed one of these. Olathe has 5 on the Kansas River, and we just installed one for the new Iatan Power Plant Unit 2. Independence has one rated at 10 million gallons a day. That's it. That was fast and furious, but if you have any questions, I'll be happy to answer them.