I recently had my concrete septic tank pumped and discovered my concrete dividing wall has deteriorated down about 6" to 10", and is allowing solids to flow into mt clear water side. I need to know how to repair the dividing wall.

I am considering two ideas. The first is to lag bolt a 2" x 12" pressure treated board to the wall and be done with the repair. This is a simple, temporary repair, but seems like it would be adequate for many years as there is little pressure on the wall.

The second option is to build a concrete form and fill the form with concrete, leaving the forms in after filling. This is how the septic repair company that pumped the tank said they would do it, for a cost of $3,000 - $4,000. I am not sure how to do this, but suppose I would through bolt two pieces of exterior grade 3/4" plywood to both sides of the divider wall, and then fill with concrete, leaving the forms in place. Other than being a messy job, it doesn't sould too difficult really.

What do you guys think?

Thanks for your help.

i'd use the wood.
my only question is if the chemicals in the treated wood will affect the aerobic action of the septic tank?
can't find anything on the net that talks about this ?

another thought... why can't you use azek (SP?) or other plactic boards?

Azek would be better that pressure treated
Eventually pressure treated will rot
Option 2 is best just make sure you drill holes in the existing barrier and use rebar to join and re enforce old and new concrete
I would still recommend removing the form after concrete sets

Agree on the Azek, you can get a 1x12x8' at the home center

I would use threaded rod, nuts and washers to sandwich the old divider wall with an Azek board on each side. Instead of filling the middle with concrete you could use some of that expanding foam. The foam would bond to the edges of the old wall and give you a watertight seal. Leave the Azek in place with the foam sandwich and it should last a long time. Use galvanized hardware.

Thanks for the replies.

Here is what I am going to do.

First pump effluent from tank into leach field.

1. Level off top of concrete wall as best I can.

2. Place about 2" of Quikcrete fast set mortar and top of wall.

3. Set concrete brick on edge into mortar to secure. Spread additional mortar onto brick. This will raise the wall about
5" total, which is enough.

And that's it. This is per the septic company that was going to do the repair for me (for a cost of $2850, including a $340 pumpout (1000 gallon tank)). Total cost will be $50, for a $2800 savings. I expect it will take about 2 hours by myself. I'll let you know how it turns out.

Sounds like a plan, post a pic of your finished work!

>I recently had my concrete septic tank pumped and discovered my concrete dividing wall has deteriorated down about 6" to 10"

I'm surprised nobody else has asked, given that the dividing wall has deteriorated, what is the status of all the other concrete walls? If others show any signs of deteriorating, it's probably time for a new tank.