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ExhibitGuy

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About ExhibitGuy

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    Uncivil Engineer

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  • Engineering Field
    Civil & Environmental Engineering
  • License
    PE
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    Casio
  • Discipline
    Water Resources

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    California

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  1. They got 1.50 inches for that one since between 3:00 and 4:00 PM it rained 0.40, 0.43, and 0.60 inches. So at T = 4:00 P.M the past 1-hour precipitation at that point in time was 1.50 inches. Therefore that past hour's intensity was 1.50 inches over 1-hour = 1.50 inches/hr The way to look at this problem is that there was a 6-hour long period of rainfall, and someone measured the rainfall in 20 minute increments. You're trying to figure out in what 1-hour time frame was the precipitation largest? This explains why they don't have the first two rows filled in for the rightmost column since it hadn't rained for 1-hour yet at T = 2:00 P.M.
  2. The unit hydrograph represents the rainfall that would occur in that particular watershed if only 1" of rain fell. At 5 hours, the unit hydrograph says there will be 125 cfs, however you measured 325 cfs. Therefore, the 1-hr effective rainfall must be 325/125 = 2.6 inches. Then that means the runoff hydrograph for this particular storm is the unit hydrograph multiplied by 2.6: If you calculate the volumes from this table, you should get 350 acre-feet.
  3. It looks like the Cumulative Inches is the Hourly Precipitation. You need to make this column since they only gave you the rainfall in 20 minute intervals. So in the last column, the 0.27 inches means it rained 0.27 inches between 1:20 and 2:20, and the 0.52 inches means it rained 0.52 inches between 1:40 and 2:40, and so on. Since you're trying to find the max precipitation, this means that between 3:20 and 4:20 was the maximum hourly precipitation at 1.70 inches per hour.
  4. No problem! They had four exams with different degrees of difficulty (Easy, Normal, Hard, Very Hard), and I would say the Normal and Hard ones were closest to the actual test, but my overall I felt overprepared. I did take each of the practice exams 2-3 times so that may explain why. But yeah, I would definitely check with the professor to see if he's not only updated the course but the exams as well for the 2018 test plan.
  5. Maybe outdated now, but here's a blog post I wrote on CPESR's class when I took it a couple of years ago. http://uncivilengineer.net/2017/10/29/cpesr-surveying-course-review/
  6. CAPLS, do you know if California is looking towards accepting the Environmental PE towards licensure as a Civil Engineer? Just asking because I have a friend who took the Environmental PE instead of Civil PE and they are banking on California accepting it in the future..
  7. No problem, it is a very tricky subject and I can never remember how it works off the top of my head (well, now I can just look back at this post!) Regarding the unit hydrograph duration, imagine if the problem was structured this way: Given: Average Effective Rainfall from Hour 0-3: 1.5 in/hr (4.5 in total) Average Effective Rainfall from Hour 3-6: 0.7 in/hr (2.1 in total) and given the 1-hour unit hydrograph in your problem statement. Solution: You could not solve the same way I did in the above post, because originally the rainfall was given in 1-hour increments. Now, in this particular problem, you have two pulses of 3-hour rainfall increments (aka two mini storms lasting 3 hours long each). Therefore, you would have to convert your 1-hour UH to a 3-hour UH. Once you did that, you could solve the same way I posted above, except you would "lag" the second pulse by 3 hours instead of 1. And why would the exam give you 3-hour pulses in the first place? Well maybe the "effective rainfall gauge" (quotes because while that would be awesome, I'm not sure this exists) only collects data every 3-hours. So the gauge says it collected 4.5 inches of water from 7AM to 10AM, then clears the data and starts a new reading for the next 3-hours. Luckily, I really don't think the depth exam will be this tricky..the problems will probably only be as complicated as your post above, or converting an x-duration UH to a y-duration UH. It would be a little cruel to combine both in one problem, but you never know. Good luck!
  8. Hi Brady, no lagging needed for this problem. Since the rainfall is given to you in 1 hour increments already, you can use the 1-hr unit hydrograph given. I'm assuming the question asks for the peak flow rate. Here's how I would tackle the problem: Think of this storm as two seperate mini storms: The first storm begins at hour zero, and lasts one hour with 1.5 inches of precipitation. The second storm begins at hour 1, and lasts one hour with 0.7 inches of precipitation. Now, the unit hydrograph tells you how much runoff you would expect from a storm with 1 inch of precipitation in a particular watershed, but the nice thing (and a major assumption of this method) is you can multiply it by the actual storm precipitation to get runoff hydrograph. Since there are two seperate mini-storms, do this twice as I've shown below. Keep note that the second-mini storm begins at hour 1! Of course, the actual storm consists of these two mini storms combined, so you need to add these hydrographs directly. Here's what you'll get The combined hydrograph shows that the peak occurs at 2 hours after the first drop of rain hits the ground from the overall storm. This peak is = to Q (peak) = 1.5 in * 1.2 cfs/in + 0.7 in* 0.5 cfs/in = 2.15 cfs. Hope this helps! Gotta love comic sans.
  9. Hi Brady, I used to get very confused about this as well, to the point I wrote a blog post to help myself remember it! Ignore the other information such as volatile solids percentage. 2% solids is equivalent to 20,000 mg/L. Here's why: 2% solids = 2 lb solids per 100 lbs of water. (unless stated otherwise). So: (2 lb solids/100 lb water) x (62.4 lb water/ft3 water) x (1 ft3 water/28.3 L water) x (1 kg solids/ 2.2 lb solids) x (1E6 mg solids/kg solids) = 20,000 mg/L OR, more simply: (2 kg solids/100 kg water) x (1 kg water/L water) x (1,000,000 mg solids/kg solids) = 20,000 mg/L Just clever manipulation of the units. Write it down and cross out the units to see for yourself. Whenever you see % solids, multiply by 10,000 to get mg/L.
  10. HI gandghpi, I have already passed the surveying exam but I have been wondering about this too. I believe EET just came out with the surveying course on the April 2017 cycle so I'm also curious if it's up to par with Dr. Ibrahim's outstanding seismic class. If this helps, I just wrote a review on my blog about the surveying course I took (CPESR) if you want to compare EET to it.
  11. Thanks Ptatohed! No I don't mind at all if its stickied.
  12. Everything looks good, except you accidentally forgot about the double negatives in calculating your R value. The R value should be +0.3333% . Using that R value i get an answer of 19 ft (B) (anyone else able to confirm?) That would be correct, but the elevation difference you calculated is between the structure and a projected line from the beginning of the curve. You want to calculate the elevation difference between the structure and the curve itself.
  13. I agree with you that it takes too much time to go through all the questions and mark them. Instead, I used the same method you did by going through each of the problems in order. However, I would only answer the very easy ones (like less than 1-2 minutes without having to look anything up) first and skip all others until I got to Question #55. While going through, I would flag questions I thought were definitely solveable, but required maybe a little more in depth analysis, and left the harder ones unflagged. The goal in the first 30 minutes of the test is to answer at least 15 with confidence, and to get a feel for the rest of the test. After my initial screening, I went through the test again and answered these flagged questions. These flagged questions are probably easy-moderate level.Then after that I went through the test once more and tried solving the unflagged ones, which weren't necessarily impossible to solve, but just required alot of time (maybe 4-5 minutes to solve). In summary, go through the test in three-four cycles: 1st Cycle: Very-easy questions only (aim for 15 in the first 30 minutes) 2nd Cycle: Easy-moderate questions 3rd Cycle: Hard Questions 4th Cycle: Brain-teasing questions (only if you feel good on 40 questions by this point), but it's fine to guess on these if you run out of time. If you can feel decent on 40/55 of the questions, you should really have this test in the bag. I also recommend making a tally sheet somewhere on your test paper so you can keep track of questions that (1) you rocked, (2) feel decent on, (3) got an answer but not sure if it's right. If the sum of (1) and (2) is 40 or more, you're pretty much guaranteed to pass. Good luck!
  14. I took CPESR and would highly recommend that class since I passed on my first try with no surveying background at all. The videos are very good quality, the instructor talks very clearly, and there are 4 CBT exams that you can do over and over. In total its 20 hours of video, and there are also quizzes after each video that ask you questions on that video's topics and the ones before to keep everything fresh in your mind. Normally I would recommend EET, but their surveying course is relatively new(it began in early 2017), and I got no response when I tried signing up for their course, which was why I went with CPESR instead. CPESR has a better track record for surveying at the moment. Besides surveying, I would recommend EET all the way for seismic (see my review) and the P.E. breadth/depth.
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