Infiltration Chambers (Storm Chambers)

[RedBauer]

I'm looking for a good resource or design manual for the design of infiltration chambers. Particularly separation from groundwater and bedrock. I've contacted a couple manufacturers, however, each of their 'simple' designs do not take into account infiltration rates, groundwater levels, bedrock elevation, etc. It appears they are just based on total volume to be stored. Which, if true, would be conservative if there is infiltration.

I've calculated I need to store 15,000 cf and have completed a subsurface investigation to determine bedrock and groundwater elevations at the site.

Any guidance would be appreciated.

 

[CivilEngAus]

Is the bedrock and groundwater levels extremely close to the surface? For only about 450^3 of storage I wouldn't be worrying about infiltration (and would assume it be zero regardless) unless you site is heavily constrained that you can't achieve this.

 

[Twinkie]

Do you have hydroCAD? Pretty much every chamber on the market is built into the program, just model them right from there.

Rule of thumb on 'limiting zones' I tend to use is minimum 2' above, but of course, always follow the local regs which may govern.

 

[darthsoilsguy2]

we do perc testing to get an infiltration rate and look at the boring logs. the state stormwater regulators require field testing so we have it done. it is common to overdesign assuming that rate will drop when silts get introduced. i've got a problem-free site with 12yrs running that we're adding to that i worked the old hydrocad out last week in the new model. without infiltration, i needed double the chambers. groundwater and bedrock elevations are important, but the soil type is definitely key.

 

[beej67]

If you *really* want to get it right, learn to model flownets.

http://water.usgs.gov/ogw/modflow/

..but I've only ran into one project where they wanted that level of detail, and it was in central Florida where dewatering operations had a potential to adversely affect adjacent water bodies.



Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[brandonbw]

We are working on a drywell right now and going through Maxwell. They took our requirement of volume and infiltration rate and spit back some calcs and a detail to further figuring out how to work this thing into the project. Very few cities will allow us to put an infiltration device in without a perc test. Though they don't normally care as much on single family residential since its so small.

Something used over here in LA, near the bottom of the PDF.

http://www.lastormwater.org/wp-content/files_mf/appxfsampledesigncalculations.pdf

B+W Engineering and Design | Los Angeles Civil Engineer and Structural Engineer

http://bwengr.com

 

[RedBauer]

Thanks for the input. I ended up modeling this in AutoDesk's Storm and Sanitary Analysis. Fairly straight forward once you figure out the input parameters.