Clarification on planting near a mound septic system

Asked July 29, 2018, 1:11 PM EDT

There is a UofM Extension posted question/reply regarding how close trees/shrubs can be planted to a mound septic system. The link referenced in the reply is broken and can it be restored? Our new mound took 42 dump trucks of material to complete, and even with the slope that was created in this instance the 20-50 foot recommended safe perimeter would not include any segment "on side slopes". I removed two cord of trees for this construction, some simply for truck access and we are very interested in restoration. Is the bottom line to keep all trees a minimum of 20-50 feet away from all system components? Could trees be planted closer if the tree base was located below the lowest component (the mound's sand layer) or can roots grow upward seeking moisture?

Thanks for the help.

Original posted reply:
Here are guidelines from a University of Minnesota bulletin:
  • Do not place trees and shrubs ON the mound; they may be planted at the foot or on side slopes. Frame the mound with trees and shrubs at a distance, but use only herbaceous (non-woody) plants on the mound itself. Trees should be planted a minimum of 20 feet from the edge of the mound. Trees known for seeking water reservoirs, such as poplar, maple, willow and elm, should be planted at least 50 feet from the mound. Shrubs should not be planted on top of the mound.

Go here to read the complete bulletin:

https://www.extension.umn.edu/garden/yard-garden/landscaping/landscaping-septic-systems/

Ramsey County Minnesota

1 Response

First, we apologize for the broken link. The University of Minnesota Extension website is undergoing a large renovation this summer and many of the links are broken.

Tree roots can grow "up", so the rule of 30 feet away should be adhered to. Here are some publications from other states' Extension Services that might be helpful. Use caution when choosing a recommended plant from these lists that the plant is appropriate for Minnesota:
https://s3.wp.wsu.edu/uploads/sites/2144/2014/12/2014-Landscaping-Septic-System-Drainfields-and-Moun...
http://www.co.waupaca.wi.us/Planning%20&%20Zoning/handouts/Suggested%20Plants%20for%20Use%20on%2...