Well the general rule in container gardening is that the containers must have some form of drainage. Otherwise the water collects in the bottom, you get ponding of the water, bacterial growth, and root rot. I can't really picture containers made from "wire forms and concrete". That would be quite unusual IME but I would be worried about that weight on the field interfering with drainage in the field. Given all the drainage problems and shallow drain fields one reads about in many parts of Florida, especially with sandy soil, I'd be very reluctant to alter my septic drain field at all. And there are literally thousands of lightweight containers with drainage holes available for gardeners to use that can be easily moved and adjusted for sun exposure without creating problems for the filed. Unlike in-ground gardening Container Gardening has its own set of unique needs so I'd suggest some in-depth reading over on the Container Gardening forum here. Dave

From reading all of this it is now obvious to me that most people have very little if any knowledge of how a septic system really works. The vegetation covering a leach field is vital to the proper performance of the system. A septic tank is a large water tight rectangular or cylindrical tank made out of concrete, metal, fiberglass or plastic. The sewer line enters the tank on one end near the top of the tank. The discharge line to the leach field exits the opposite end of the tank 6" below the level of the sewer line. Inside the tank there is a baffle that divides the tank into two chambers, the sediment chamber and the digester, although in truth the digestion takes place throughout the entire tank. As the effluent enters the first chamber it is a mixture of water, fecal matter, soap, household chemicals, organic kitchen waste, human hair & skin cells, metals, plastics, paper, kids toys and no doubt a couple dozen golf balls as some idiot demonstrates his new toilet to the neighbors. As that mess enters the first chamber the heavier materials drop to the bottom of the chamber while the lighter floatable solids remain near the surface where they are slowly broken down into a thick slurry. The slurry then passes through the baffle and into the digestion chamber. Inside the septic tank there is a colony of "Anaerobic bacteria" (bacterial which thrive in the absence of air) that literally eat the waste and in the process the waste is converted to a gray water liquid. The gray water then flows into the leach field pipe system. In the leach field pipe system there is another colony of bacteria, only this time it is "Aerobic bacteria" (bacteria which thrives in air). The aerobic bacteria then eat the remaining waste in the gray water and they give off water and produce various nitrates. The final phase of the waste treatment process is done by the vegetation covering the leach field. The plants(generally sod) roots take in the water and nitrates. During daylight hours the plants take in some carbon dioxide through their roots from the leach field but generally they get the most of their carbon dioxide from the atmosphere. Through the process of "Photosynthesis" the plants use sunlight energy to convert the water and nitrates to the nutrients the plants need for growth. In exchange the the plants give off pure oxygen and water vapor into the atmosphere. Sod is the preferred covering over a leech field because a healthy stand of sod promotes earthworms which aerate the soil allowing air to get into the leach field pipe to support the aerobic bacteria colony. If you were to cover the leech field with P-gravel or mulch there would be no vegetation roots to absorb the water, nor would there be sufficient oxygen getting into the leach field to support the aerobic bacteria. The end result would be a saturation of the soil surrounding the leach field and the raw gray water would percolate to the surface creating a health hazard. I have lived in regions where they don't even allow you to sit a picnic table over the leach field, although I never heard of anyone getting busted for it.

Use hand gardening tools or a shovel to dig down about 12" in the area of the system. I know that aerating is not likely to go deeper than 8" and probably not more than 5".

The depth of burial must consider such factors as frost depth and prevailing geological conditions. In my region the frost depth is 30" and all lines must be a minimum of 6" below frost depth therefore our minimum depth is 36" and maximum is 48". In regards to pumping, i fail to see why so many people insist on annually pumping a septic tank. If the tank and leachfield are properly installed and functioning correctly the only time it should require pumping is when there is a buildup of non-digestible waste such as plastics which effects flow. In my region the need to pump septic tanks is so seldom that there is only one pumping truck in the county and it is currently for sale because of a lack of work. The septic tank at my mothers house was installed in 1965 and it has never been pumped.