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Hi All, Do nominal pipe sizes come in odd numbers or are they always even numbers ( 4 inch, 6 inch, 8 inch, etc). I was solving a fluid mechanics problem where two pipes were in parallel and you had to solve for the diameter of one of the pipes. I got the right answer of 4.8 inches. Based on...

@WaterchildI might take PPI On-Demand course but it's so expensive lol. I was thinking of purchasing the one-month option as opposed to the 3 month option since it's cheaper. Which package did you purchase? Is one month sufficient to go through all of their quizzes, lectures and problems? Thanks!

@Waterchild I was planning to take EET WRE course to focus on water and wastewater topics, but maybe PPI2Pass is worth it for the CBT exam? How many practice quizzes and exams do they give? Did PPI cover all topics?

@WaterchildHope you get the green pass :) How was your experience with the test?

@GirlsCanDesignThank you for sharing your stories and experience :) very happy for you!

@GirlsCanDesignwow that's awesome - congratulations on the pass 😀 how did you feel about the exam overall? I hope those of us who still need to take it will have a good chance of passing =p I am worried about air section since I don't work in that area.

How did you guys utilize the Intro to Environmental Eng book by David & Cornell? It was recommend by a lot of the folks here & has practice questions at the end of each chapter which seem pretty good but it doesn't come with a solution manual or answer key! Was wondering if theres...

@ExhibitGuyediting my post: thanks I understand the problem now!! 

@ExhibitGuy@vhab49_PEThank you both! I think I see the pattern now. Since the increments are given in 20 min, I have to add the 3 values to get the cumulative inches per hour. Then move on to the next row and repeat.

@vhab49_PEHello, Sorry I'm still not seeing how the math works here. Just for example, at 3:40 - 4:00 pm, how did they arrive at 1.50  inches? Wouldn't they have to add the previous value (1.50) plus the current increment (0.60) and arrive at 2.10 inches, not 1.50?

Additionally, I'm stuck on this problem below as well. The first two columns are given. I was able to calculate the volume as 134.2 ac-ft for an effective rainfall of 1 inch, which I thought were the answers. But the solution doesn't make sense to me.

Hi All, I am given the first two columns and asked to find the maximum hourly precipitation in inches/hr. The last two columns are part of the solution. I'm not really understanding their solution so would anyone please explain why the cumulative values need to be taken? Also, it seems they...

@Jbone27 PEthanks! I think i'll go with your explanation as it makes more sense than linear interpolation haha

@NikRIm only using the figure provided in my original post. Can you try interpolating it based on this curve and see if you get the same answer as mine? @jgianghmm I never thought of "curve" interpolatiom but i have no clue how to do that either lol o.O

@NikRYeah I read the values from the curves but my textbook doesn't have the same answer. Here is how I did my interpolation: At 17 min: 20 year    5.7 in/hr 25 year       X 50 year    6.8 in/hr Interpolation equation: [20 - 25] / [20 - 50 ] = [5.7 - x] / [5.7- 5.8] Solving for x gives me...

@NikRCouldn't I just take the values for the 20 year and 50 year storm at 17 min?

I'm trying to obtain the intensity value from the IDF curve for a 25 year storm. The time of concentration is 17 min. Since 25 year storm is not there, how would I interpolate? Do I just take the average of the 20 year and 50 year value? Please let me know what approximate value you get =] Thank...

I'm trying to calculate the hydraulic radius but I think the solution in my textbook may be wrong. But I wanted to see if anyone here might be able to point out my mistake, if any.  A trapezoidal channel has a bottom width of 3 ft and side slopes of 2 ft vertical and 1 ft horizontal. Assume a...

Hey All, I plan on taking the cbt environmental exam and purchased the Introduction to Environmental Engineering 5th edition by Cornell. There are some good practice problems but it seems like they only give you the answer for a few problems. Even for the ones that do have the answer given...