Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Help Please - permeability testing above groundwater table

Help Please - permeability testing above groundwater table

Help Please - permeability testing above groundwater table

Here is my issue:

I was recently tasked with conducting field permeability tests inside cased/partially cased boreholes at a site with low permeability (glacial till) deposits and a deep groundwater table to aid in appropriately sizing a proposed stormwater infiltration chamber. All of the references I have come across to calculate the horizontal and vertical coefficients of permeability based on variable (falling) head tests are with respect to infiltrating into saturated (i.e. below the groundwater table) soils. However, in my case, the groundwater table is located at great depths below the proposed base of the infiltration system, and I am 100% certain that I was infiltrating into unsaturated soils. A summary of my testing procedure is as follows:
1. Advance boring to a depth of 14 ft. (proposed depth of chamber base) using driven steel casing and rotary drilling methods
2. After the casing was "washed" out, we filled the casing with 2 ft. of filter sand and lifted the casing up 1.5 ft. (leaving 6 inches of sand inside the casing, and 1.5 ft. of sand below the casing)
3. Fill the casing with clean water to the top (reference point) and measure the head drop at specific time intervals

Am I overthinking this? Is is simply a k = Q/A scenario? Any and all advice is much appreciated.

RE: Help Please - permeability testing above groundwater table

No need to double post because most of us look at many rooms.

RE: Help Please - permeability testing above groundwater table

sorry oldestguy - but I can't find the other post . . .

https://www.rgc.ca/?page=page&id=62 - try this as a start - Infiltration testing in vadose zone.

RE: Help Please - permeability testing above groundwater table

Thanks BigH, but I didn't find any info at that link that helped me. Most of those methods use permeameters that allow a constant head to be applied. In my case, we simply filled the casing and measured the head drop through time.

RE: Help Please - permeability testing above groundwater table

Pretty much like a percolation test for septic system design. I have an article on constructing a constant head percolation 'tester' that I'll try to find.


RE: Help Please - permeability testing above groundwater table

Maurice Cassan in his book "Les essais d'eau dans la reconnaissance des sols" (Eyrolles, Paris, 1980) wrote a chapter about permeability tests in dry soils. Basically, it's a Lefranc test with a special interpretation by a russian scientist called Nasberg.

RE: Help Please - permeability testing above groundwater table

there are factory tools to help. Guelph and Johnson make permeameters, based on the equations of the USBR.

There is also a method adopted by the county of Fairfax, Virginia that includes a 4- or 5-in diameter pvc pipe placed to the target depth and surrounded by bentonite. After a 24-hr soak, you take measurements of infiltration rate over time.

All of these tests engage very small areal footprints of the soil and conclude some infiltration rate for those boundary conditions. When you scale the test results to the actual area of the infiltration practice; however, the results may not be as intended. . .

To take an area of 10 or 20 ft square and infiltrate, you are assuming that the water has some place to go. Does it? At some point a mound will develop and a mound (i.e., by its very definition) mobilizes horizontal flow, so, the gradient=1 condition is not what's driving infiltration. All infiltration tests above the water table area based on gradient=1.

Good luck.


ípapß gordo ainÆt no madre flaca!

RE: Help Please - permeability testing above groundwater table

Thanks f-d, I have looked into that method based on some of your other posts: but, unfortunately I have already completed the tests and the procedure I used was not in accordance with the Fairfax method. Would any of Hvorslev's equations apply to the procedure/boundary conditions of my tests?

RE: Help Please - permeability testing above groundwater table

Sure, it's worth looking at the Hvorslev boundary conditions and seeing if the equations give meaningful results.

I'd also suggest grain-size correlation to permeability, to get some sense of what you expect. There are correlations to D10 and D20, that I've used with some success.


ípapß gordo ainÆt no madre flaca!

RE: Help Please - permeability testing above groundwater table

Some others - may or may not help you - but good to have - especially the Soakaway reference
http://www.eng.utoledo.edu/civil/heydinger/unsatur... (seems to be lab oriented, though)

BRE Digest 365 - Soakaway Pits
http://idox.bathnes.gov.uk/WAM/doc/BackGround%20Pa... (Design of soakaway pit - talks about infiltration)
http://www.yourspreadsheets.co.uk/soakaway-design.... (a free "lite" spreadsheet is downloadable)

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - How ESI is Helping Move New Medical Device Product to Market Quicker & More Cost Effic
Early Supplier Involvement has long been a strategy employed by manufacturers to produce innovative products. Now, it almost seems like a necessity. Because decisions made in the design phase can positively affect product quality and costs, this can help add value to OEM bottom lines. This white paper will discuss many facets of ESI, including why it’s so valuable today, what challenges limit the benefits of ESI, how cost is impacted, and more. Download Now
White Paper - Moving to a Driverless Future
This white paper describes what we see as the best practices to support a sustainable engineering process for autonomous vehicle design. It exposes how to use simulation and testing in common frameworks to enable design exploration, verification and validation for the development of autonomous cars at a system, software and full-vehicle level to drive a mature product development process for automated driving. Download Now
Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close