The Kingsville area is "blessed" with some of the worst soil for supporting septic systems and ground disposal of waste water. The word "soil" is not even appropriate, since much of the area is just deep clay, without any real topsoil. As a result, most areas in Kingsville will not pass a "perc" test for a traditional septic tank and trench drain field. The next available alternative is a "sand mound". While some still seem to believe that a sand mound is used when the ground does not perc, the fact is that a traditional drain field can be used if the perc rate is faster than 1 inch per 30 minutes, while a sand mound may be used for rates of 1 inch per 2 to 60 minutes. With rates slower than that, not even the normal sand mound can be used. Many areas of Kingsville will not even support a sand mound. My backyard failed this test in 3 places.
The State considers both the traditional septic tank/drain field as well as a sand mound as a "conventional" system, thus both are allowed equally under state law and county regulations, including for new construction.
Some have argued that a sand mound is "cheating nature" and that it is "not a question of if it will fail, but when". One could argue that the traditional drain field is "cheating nature", since it allows more water to be dissipated than a single hole in the ground would (an outhouse). All systems will fail someday, even a traditional system. So far, experience seems to indicate that sand mounds, with the engineering, construction, and maintenance requirements, are at least as reliable as traditional drain fields (which often go decades without maintenance). There are probably many people in Kingsville who do not even know where their tank and drain field are, since they were installed at a time when the entire system was buried and forgotten. They can't even pump them out every 5 years as recommended.
Residents on a small lot with an old system should be concerned about what will happen the day it fails. It is quite possible that the ground will not perc sufficiently to allow either a tradition drain field or a sand mound. They may then have to spend $25,000 - $30,000 for an advanced drip-irrigation system, if they even have the room. That is where the real problem comes in. There are many older homes in the heart of Kingsville on half-acre lots or less. They simply do not have the space for any viable system. They could easily be stuck on a holding tank - emptied every couple weeks - until a solution is brought to them (a sewer line).
In the long-term, it is likely that an extension of the municipal sewer system or a small, community system will be required to serve the denser, already built portions of Kingsville. This has already been done (outside the URDL) in Bowleys Quarter due to environmental concerns. Of course, a way will need to be found to do it such that this will not allow building on any lot where such building is currently prohibited by the small size. (The requirements for a well should still prevent such construction.)
And, as the state puts more and more restrictions on conventional on-site disposal systems, the day will surely come when homeowners in Kingsville will be required to upgrade their existing systems to what is called "Best Available Technology" to remove nitrogen (or get rid of their septic systems altogether). That day of reckoning is coming soon!
Reference: COMAR 26.04.02.05