Question:
I’m about to install a residential system in rural western North Carolina. There seem to be many things to consider that, while not required here, would improve the long-term performance of the system.
As an example, I don’t understand why there is not a locater installed for the access opening. It could be something as simple as a bird bath so that it doesn’t demand a search every time. Or a schematic drawing of the actual installation if something gets wonky in 20 years. Maybe adding more drainfield than required. Or a larger tank than the minimum to accommodate future unplanned expansion. I would welcome the perspectives of folks who have dealt with these issues.
Answers:
It all boils down to cost and whether you explain your recommendations to the homeowner. Tell them why you are doing what you are doing and give them the cost difference. You could make the system too big, which means it would be too costly.
As for locating, drawings and pictures work well. Our system was just installed, and I measured from two points to the tank corner. I used the corner of the house and the well. Finally, the city or county had better have records.
One thing we had to consider was that we plan on installing a lift station in the basement at some point. That requires a slightly bigger tank. That is a rule here in Minnesota — it must be at least half the size of the septic tank itself. Our tank is 1,500 gallons, so the lift station tank is 1,000 gallons.
Installing risers to grade would eliminate both difficulty finding the tank, and the need to dig it up for servicing. Money well spent in my opinion.
All of the things you suggested are fairly commonplace with most installs. It just depends on what people are willing to pay for. Most people are too price-sensitive to add all the things you presented.
One of the items on your list will definitely increase your reliability and that is an at-grade riser and effluent filter. The primary cause of failures on properly designed, sited, and installed systems is lack of maintenance. With good access for cleaning and regularly scheduled filter maintenance, the system would probably outlive the occupants.
One thing you allude to that has not been specifically addressed is the leachfield. In my opinion, installing an oversized leach is not anywhere near as effective as installing two of them, possibly even slightly undersized, only for economy, but with a valve so you can use them one at a time.
This way, you can use one for a year, then rest it for a year while you use the other one, or cycle them every two years. The advantage is that a leachfield, while lying fallow, will literally come back to new. Also, if for any reason, you kill one of them, you can always resort to the other one while you get the failed one fixed.
The biomat thickness depends mostly on the BOD of the effluent. If your tank is too small, or you are overloading the system, the BOD will be high and will lead to a thick biomat layer. High BOD is usually caused by having too much undigested food and animal fat dumped into the system. If you don’t overuse your garbage disposal, and don’t dump grease down the drain, you should be okay, as long as the system was designed properly in the beginning.
