question on mounding analysis

[tsli001]

Hi guys:

My state just add new regulation on stormwater regulation. It stated that any type of exfiltration system(detention pond, subsurface water storage system..etc) design, if the system is less than 4 feet above teh seasonal high groundwater, a mounding anaylsis need to be provided. A Hydrologist is arguing the mounding anaylsis is only for acquifer. So, is not necessary to do such analysis. I was wondering can this Hydrologist argurement can stand againt state regulation? If not, is there any argurement can argure that there is no need to such analysis.

thanks

 

[singingk]

According to german jurisdictions ex-(I would prefer to say in-, but I'm not a native speaker) it is neccesarry to keep a distance between the bed of the ex- (in-) filtrations and the maximum groundwater level of minimum 1 m (approx. 3 1/3 ft.) to prevent any possible groundwater contamination with certainty. It does not matter wether the groundwater level encountered is the actual aquifier or ponded water. What is a mounding analysis?

 

[muuddfun]

I doubt that the regulators will buy your hydrologists arguments, they usualy don't see the difference between any near surface perched conditions and any deeper aquifers. In my experience they treat it all the same, thus the regulation, especially if the water is that shallow.

The only arguments against needing such analysis are that you are assuming that the amount of water being infiltrated is only going to occur intermitently and therefore will have plenty of time to dissipate any buildup in the mounding effect before the next event. That would probobly only work in parts of the country with very infrequent precipitation. Otherwise you will need to assume that the mounding will occur. By the way 4 feet is very shallow and you may have other problems to deel with, be careful that your systems will work at all.

 

[tsgrue]

.

If the "hydrologist" stated such, then the "hydrologist" is incorrect. Check out the papers at "ftp://blwi.com/PUB/IFSMM/", especially those on mounding. Analyis software for mounding analysis can be found at "

http://hhwq.blogspot.com"

and at "

http://dnr.wi.gov/runoff/stormwater/technote.htm".

.



tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation

http://hhwq.blogspot.com