Peter Elson

Hi Rufus

Excellent post, I am an engineer dealing with water storage systems and you managed to give a great discussion of all the important points, I was not surprised to read at the end that you are a licensed plumber.  The only comment I would add is to keep in mind that water is very heavy one liter (4 cups) weighs one kilogram (2.2 pounds) so any storage structure must be well supported keeping in mind that fact that soil will settle if not properly compacted, which can lead to collapsed structures.

Peter Elson P.Eng

I am glad to hear that you get your system inspected, always a good plan.  It is hard to assess your situation without knowing the details, however, it is most likely that your drain field consists of a series of parallel pipes with two rows of holes (at 5 and 7 on a clock face) which spreads the liquid from your septic tank over the whole area of the field.  Which means that you don't want to plant anything over the field that may send roots down into the area around the pipes.  It is also important not to drive over your field or septic tank or erect any structures which might interfere with basic maintenance.

One more thing, I would suggest pumping your septic tank every 3 to 5 years whether you think it needs it or not as solids will settle out and not completely break down.  When you do have it pumped be sure to have all the solids pumped out (the liquid doesn't really matter) and don't let the pumper truck operator convince you to leave some solids to keep the tank "working" there is enough bacteria in very flush to keep the tank operating as designed.

I am a water/wastewater engineer and have designed and repairs many typical septic systems.  It looks from the picture that you have a pumped system (probably a sand mound system) where the overflow from the septic tank is pumped to the green pipes.  The green pipes have holes at 12 o'clock from which the pumped liquid shoots up and hits the black half circle then leaking into the sand where is receives treatment.  It is VERY important not to plant anything over the field that could possible send roots down into the system, the roots will find their way into the pipes and plug the system and are costly to remove.  Also, be sure to clean the screen on the septic tank, where it overflows to the pump chamber, at least twice a year and pay attention to what chemicals you are using in your house.