×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

(OP)
How do I use my perc test data? I understand the "pond outlet device" and "discarded" Can I use ft3/ft2? for soil percolation rate?

I am designing a drywell system for a residence. I am an architect so not my main line.

Thanks
Dave
Replies continue below

#### Recommended for you

Yes, you can convert the perc rate to an equivalent velocity, but you also need to use you judgement to determine that the entire (larger) pond will behave according to that value over an extended period of time.

Using a percolation rate

A measured perc rate can be converted to an equivalent exfiltration velocity by the following equation. However, other factors must be considered to determine if this is a reasonable design value for a proposed exfiltration area. (For example, can a large pond be expected to perc at the same rate as a small test pit over a period of many hours?)

V = 60 / P where:

V=Exfiltration velocity [inches per hour]
P=Perc Rate [minutes per inch]
60=Units conversion factor

Peter Smart

(OP)

I had an 8" dia perc hole, the sides were lined with a metal sleeve, the final hour test was a 10" drop. Do i use 10"?

also is it possible to enter a clogging factor?

If i have a battery of Cultec 330 XLD chambers with an invert of -4', Do I want to size my pond such that the water rise maxes out at about -1'?

Thank you.

You will have to determine the exfiltration rate that is appropriate for your purposes. You could reduce the discharge multiplier if you want to allow for "clogging", or just use a lower exfilt rate.

Again, you will have to determine the appropriate peak WSE for your specific situation and design goals. There is no single answer. It all depends...

I'll leave it to the seasoned H&H engineers on the forum if they want to offer more detailed design guidance, but I'm going to limit my comments to specific modeling issues.

Peter Smart

With prefab chambers you can design storage above the chamber in the stone, you aren't limited to a specific elevation.

But as Peter said....it all depends on what you're trying to do.

#### 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.

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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!