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Hello, I am working on an arsenic removal project from wells. The water is fairly clean but with 0.05 mg/L of arsenic. I found adsorption and ion-exchange resin are the most commonly used technologies. Does anyone have any recommendations? S

Thank you!

Hello all, I am trying to get a volume of 12.5% sodium hypo based on different diluted solutions (as shown below). The 12.5% volume (gallons) needed was calculated based on the dilution (%) times diluted volume (gallons) divided by 12.5%. My question is, why the 12.5% volume needed are the...

Hello Peter, Thank you so much for the explanation. It is clear to me now. Best, Serene

Hello, I am trying to model a runoff drain to a swale. The swale is inside the drainage area. In the HydroCAD model, I have one subcatchment going to a reach(open channel), but the TC in the subcatchment area includes the swale that is going to be discharged to. I was wondering if I should...

The question used in the NCEES official practice is using the SI one. However, everything given is in gpm and ft. The solution just plugged in all the numbers to the SI equation and obtain an answer. I think that was a mistake.

Hello, The Hazen–Williams equation related problems and answers look incorrect to me. It is using the SI unit equation to solve the problem while all the calculation plugged in the equation has US units. I was wondering if anyone else noticed this??? Thanks, Serene

Thank you Peter.

Hello Peter, I do not think it is significant, so the outflow shouldn't be zero, right? Thanks, Serene

Hello, I was wondering how does HydroCAD recognize if I am modeling a bioretention pond or a regular detention pond? I understand that for the bioretention we can add exfiltration and underdrain (pipe). But is it possible that the inflow is very little that nothing is coming out (outflow = 0...

Got it. Thank you, Peter!

Thanks Peter, I'll try both. What about the to model the dry swale using "Pond"? I'm using a pond storage with outlet "exfiltration" and "broad-crested weir", what should be the conductivity in the "exfiltration"? The current model is giving me very small exfiltration at the 100-year storm event...

Hello Peter, Do you mean the Tc line? Would the shallow concentrated flow work as well?

Thank you for the suggestion. I was also trying to model the dry swale using "Pond", but my swale as a 4% longitudinal gradient and I can't find any outlet device that can describe it. Thanks again, Serene

Hello, I was wondering what method I should use when Tc line is going to a dry swale? There is an underdrain pipe, but I don't think it is proper to select the "pipe channel" method because the grass cover on top would provide some detention. Thank you for your time. Best, Serene

Got it, thanks, Peter.

Hello, I was directing the runoff from two drainage areas to one detention pond, but the inlet flow at the pond doesn't equal to the sum of the runoff from the two areas. Could you please help me to understand what is wrong? Thanks, Serene

Thank you Peter.

I was trying to adjust the parameters (i.e. elevation, dimension, length, etc.) for outlet culverts, orifices, and weirs to achieve the desired flows at three rainfall events (i.e. 1-yr, 10-yr, and 100-yr). However, it is very difficult to adjust the parameters manually to meet one rainfall...