Why Tanks Break Down

I read the article on hydrogen sulfide and septic tanks (“Why Do They Break Down?” Onsite Installer, May 2011).

As a designer/installer in New Hampshire, I am responsible for the maintenance of a five-building condominium that has an onsite system. Each building discharges into two septic tanks, which discharge into a single pump station with dual pumps. The pumps discharge into a small distribution box that splits the flow and discharges to two 12-outlet distribution boxes that flow to twin, vented distribution fields.

The small two-outlet distribution boxes, which are not vented, are the problem. The hydrogen sulfide gas collects in the concrete distribution boxes, and over the last 15 years it has caused the concrete to disintegrate into sand above the waterline in the box.

My solution to this problem has been to break out the concrete boxes without disturbing the pipes and fit a plastic distribution box in their place. I reinforced the sides of the plastic boxes with bricks to give them some structural strength. I am sure that the gas is what causes the concrete to become sand.

David A. Berry, P.E.

Chief Engineer

Berry Surveying & Engineering

Barrington, N.H.



Discussion

Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.