Is my soil adequate for a dry well installation to collect roof runoff?

Question

I did a soil percolation/infiltration test to determine how quickly water drains through the soil:

Dug a hole approximately 12" in diameter to the planned depth of the dry well.
Filled with about 2 feet of water
Let it drain completely to saturate the soil
Filled it again with another 2 feet of water
Measured total drainage after 1 hour
Result was 6.5" of drainage after 1 hour, or a little more than 1" per 10 minutes

Assuming I've calculated the right number of dry wells and permeable gravel backfill to surround the wells (that is total storage volume is appropriate for rainfall rates and roof area), is that soil drainage rate adequate for this application?

designerinexile · Answer

I’d say yes. That’s a pretty good absorption rate. I work with a city program building residential rain gardens for storm water management and the guidelines for passing infiltration testing for those is 1” per hour to run 600 sq ft of roof drainage from a downspout to a designated garden site.

Answered by designerinexile on July 23, 2021

Is my soil adequate for a dry well installation to collect roof runoff?

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