In our previous column, we outlined a situation that was brought to our attention by a homeowner. We discussed why we thought there were problems with the tank being watertight and why the mound treatment area should utilize pressure distribution instead of gravity. But the whole description he provided of the tank and the piping arrangement got our attention.
Here is the description:
“When I’ve had the septic system pumped every time since it was new, the water level in both sections of the divided 900-gallon concrete tank has always been about 8-10 inches below the top of the tank. The last time I had the tank pumped about 6 years ago, the technician pumping the tank noticed the bottom of the ‘riser pipe’ at the outlet side of the system was still closed from when the tank was installed about 15 years earlier.
“The technician got a hacksaw and cut off a small section at the bottom end of the riser pipe to open it up, because he said the water that goes to the drainfield should flow through the riser pipe and not as it apparently has been for the past 17 years by flowing over the top of the ‘baffle.’
“When I had the tank pumped about 14 months ago, I should have asked the technician if there was any way to look behind the baffle that the riser pipe goes behind to see if the top outlet of the riser pipe was also molded closed and the water is still flowing over the top of the baffle and directly into our drainfield.
“It doesn’t help that I’m a worrier, so I don’t know if I should even check this out further after 22 years of no problems, or I should pay someone $500 to $1,000 to dig that section of the tank to simply check to see if the top section of the riser pipe is open or still molded shut and the water (scum layer) is still flowing over the top of the baffle.
“I don’t know where the water level in the tank is in comparison to the outlet pipe, because I didn’t think about looking 14 months ago. Should I just relax and let it be since there hasn’t been any problems after all these years, or should I have the issue looked at and corrected if necessary?”
MORE TO THE STORY
As we corresponded with the homeowner, we thought there were plenty of reasons why he should not just “relax” because he was not seeing any problems. We were intrigued by this other “riser pipe” going up through the outlet baffle and out of the tank inside the larger 4-inch pipe out of the tank to the soil treatment area. Then there is the description that about six years ago a service provider had noticed this pipe and investigated to find it was capped or blocked off.
Since the tank has two compartments, it would seem logical that a pump was supposed to be connected to this smaller-diameter pipe, which would be consistent with the second compartment acting as the pump tank for a pressure distribution network.
The result of this configuration means that the tank over all of this time has operated “over-full,” which as the service provider indicated six years ago, the effluent and the floating scum are able to flow over the top of the outlet baffle downstream to the soil treatment mound.
Cutting off the bottom of the small diameter pipe probably helped with moving effluent from the clear space to the treatment area, reducing the amount of scum and solids delivered to the treatment area. Over the 17 years or so it operated this way, a lot of scum could have been delivered to the mound, which would result in plugging the soil pores in the infiltration area, reducing the capacity of the system to accept and treat the effluent.
All of this is distressing to us because it appears that the original installer knew that the mound should have a pressure distribution network and pump, but for whatever reason, the installer did not complete the install. Instead, they left the system in a condition where it would appear for a time to operate correctly, but also limited the effectiveness to accept and treat effluent, setting up the system for ultimate hydraulic failure by delivering solids to the infiltration bed.
WE SUSPECT NEGLECT
Next, it took 17 years, with the system being looked at every five years, before a service provider thought it was odd there was an additional pipe through the outlet baffle. The homeowner had indicated there were two 4-inch “pumpout” ports. We can only assume the first service providers that pumped the tank only used these ports and did not open the tank to inspect its contents and how it is operating.
As we have stressed in previous columns and elsewhere, a tank cannot be adequately cleaned through 4-inch pipes and the only way to provide that cleaning is to open the tank manholes. If this had been done, it is likely the tank operating over-full would have been identified much sooner, avoiding years of damage to the mound treatment unit.
Eventually a service provider opened the tank during pumping and identified what they saw as a problem and tried to correct it by opening up the small pipe. It just seems to us, in fairness to the homeowner, they should have at least suggested having an installer look at the system to see if it was installed properly. As the homeowner indicates, he is still not sure the tank is operating at the level it should (we suspect not) and whether there is damage to the treatment mound (we suspect there is).
In our industry, we need to strive to make sure situations like this do not occur. And if we see them and identify them, then work to find the ultimate solution to the problems and not just a temporary fix.
