Chapter 9
“What are you up to this morning?” asked Keith as he came down the stairs and joined Clark at the breakfast table.
"Well, I mentioned to you yesterday morning at the coffee shop that I had a little deviltry in mind. I’ve got a co-worker who is, in my opinion, a genuine horse’s butt. A little over a week ago, the boss had a notice up asking for a volunteer to go out to the Rio Puerco to bring back some mud balls for analysis by a summer school class in Soils in the Civil Engineering Department. When flowing, the river erodes its clay-like bottom and rolls it up like a rug or like grass sod or a ball for a snowman. There’s one particular spot on the Puerco where it makes a dramatic turn, and these erosion balls get pushed right on up a sand bar by the force of the current. This CE professor asked for three or four of them and they are extremely heavy and you have to carry them up a steep embankment. Well, this s.o.b. co-worker, David Arthur Cabot Ward – yes, he’s from back east somewhere and loves his name – thinks he’s cute by writing my name on the notice. He’s definitely got a screw loose somewhere. I could hardly tell the boss that I didn’t do it or try to back-peddle with some lame excuse, so I got stuck with it. Turnabout is fair play and I’ve got a great idea for getting even!”
“Love it!” said Keith. “What do you have figured?”
“Well,” Clark continued, wrapped up in his thoughts. “This upcoming week, various field men are scheduled to go out to visit the various sampling stations and get them ready for the monsoon season. Each station has a dual A-frame cable car apparatus stretched across the river with the car chained at one end, a locked special tool and supplies box nearby, and a vertical culvert set in place with a time recorder in it in a locked box at the top and kind of an elevator float in it at the bottom of it. While a counterweight helps keep the float properly engaged over the recorder, the float invariably becomes silted in as the water flow ebbs from its most recent high because of mud coming in the inflow holes at the bottom. So you have to dig down to open a door at the bottom of the culvert and then dig out underneath the float so that it operates properly. You have to check the recorder batteries as well as check the inked stylus and the recorder paper. All this for a continuous record of how high the water was i.e. the gauge height. When associated with a weir, you have a known cross-section for the river whenever. One merely multiplies that figure by the speed of the water, as I’m sure you are well aware, to then calculate the cubic feet of water per second going down river at any particular point in time. I’ve been told that the average speed of the water occurs at .6 of the depth or, alternatively, the average of readings at .2 and .8 of the depth. Judging from lab studies, the surface velocity is approximately .9 of the average velocity of a given stream. Maybe they use an anemometer or something similar from time to time or maybe they survey the angle of the particular site somehow. I’ll have to take their word for it since I’ve never taken a velocity reading other than a surface one and that’s solely for my own safety when taking samples. You throw a stick in the current and count the seconds it takes to go 10 feet down river. If the depth times the speed approaches 10, like 10 feet deep going 1 foot per second, obviously you can’t wade it as it’s in all likelihood over your head – even mine. On the other hand, if the depth times the speed approaches 10, like 1 foot deep but going 10 feet per second, you can’t wade that either because the river will erode around your feet so fast that you won’t be able to walk. So you have to judge by some lower number whether you’re safe taking your sediment samples by wading or whether you should use the cable car. If it’s night, and most of our thunderstorms do indeed occur in the late afternoon, you’re most likely to opt for the cable car as most of our field men do. Of course, it’s later analysis of sediment samples as a percentage of the water flow that finally gives us our desired information. You might be interested in knowing that two rivers in the western United States, when they run, are technically mudflows i.e. more silt than water. One is our own Rio Puerco and the other is the Dirty Devil River in Utah. But I digress!"
Keith took advantage of the momentary pause in Clark’s near soliloquy, “Interesting. I’m glad you think that’s fun. But I must have missed the part where you get even.”
Clark continued, “Well, tomorrow I’m slated to go down to New Mexico Tech in Socorro to pick up twenty cases of one pint milk bottles. The USGS contracted with some guy down there to acid etch a portion of the lower part of each bottle. We use them for our sediment samples and the etching allows us to write the station, the date, the time, and the gauge height for each sample right on the specimen itself. On the way down, I pass right by our lower Puerco sampling station at Bernardo. It’s right before the Puerco dumps into the Rio Grande and the station is only a city block off old US-85. You can see it on the right from I-25 heading south. I saw on the assignment sheet that David Arthur Cabot Ward has that station on his task list for Thursday. I’m going to unlock the cable car and let it gravitate out to the middle of the cable. I don’t know if he’s ever had to retrieve one, but it’s terribly uncomfortable and scary as hell whether there is any water in the river or not. You have to climb up on the cable yourself and, while sitting on it with one leg hanging down to maintain your balance, ease out a little bit at a time. Not only does the cable bite into your leg, but every time you move, you change the center of gravity on the cable and the car moves toward you with the real prospect of its back wheel rolling right on top of your hand. Believe me, it’s no picnic. He’s gonna feel like one of the flying Wallenda family before he fetches the cable car, clambers into it, pulls it back hand over hand, and has it properly locked up again.”
“Ingenious,” said Keith. “You have a key. It’s equipment that you are authorized to use. You’re not destroying government property. Will you leave a calling card for your friend?”
“I think he’ll figure it out. Are you interested in coming along?” urged Clark.
“I think I have my own fish to fry, but please accept my sincere congratulations,” replied Keith as he finished off a bowl of cereal. “Have you had a chance to call Jenny yet? I’m eager to make my report to Kayla,” laughed Keith heartily.