Here are the answers to O&M Quiz No. 2.
1. T or F - Settling around the riser of a new septic tank may be a result of a leaking riser/tank seam and should be investigated.
Answer: True. It should be investigated to determine the cause. One possibility is that it was not properly set to be watertight, allowing water and associated soil to wash into the system. Left unchecked, the excess water can result in hydraulic overloading of the system. There are other possible explanations such as natural settling, since the backfill was not compacted around the riser. The problem should be fixed to prevent problems in the future. This is one reason I always recommend revisiting a site after a repair or installation after about a month just to see if there are any potential problems.
2. T or F - Surface-water intrusion is a problem for all systems.
Answer: True. As indicated above, any extra water that enters the system is a negative from a hydraulic overloading standpoint. It is why all piping, tanks and connections need to be watertight. If they are not, they should be repaired or replaced until they are watertight.
3. T or F - Land surface depressions around a septic tank can be a problem from a stormwater infiltration perspective.
Answer: True. Again, any location where there can be additional water entering any part of the system is a negative. Depressions over the tank can result in runoff ponding over the top of the tank and will eventually erode around the tank or the trench along the supply line from the tank to the drainfield. The backfill over the tank should be slightly crowned following installation to allow water to run off away from the tank and system.
4. T or F - Presence of a patio or driveway over a drainfield restricts oxygen flow and hinders wastewater treatment.
Answer: True. Even more important, though, may be the lack of access to the system for maintenance and management. In addition, in my part of the world there is potential for the system to freeze if there is not additional insulation.
5. T or F - A perennial flower garden is considered an encroachment on a septic system and should not be allowed.
Answer: False. Perennial means permanently established vegetation, so this would be allowed as long as the plants selected have shallow, fibrous root systems that will not be aggressive in their search for water, causing root penetration problems.