It was never an unusual thing for you to pay extra care to your sand mound. Your septic professional broke the news to you that you had to have a sand mound for a septic system because the water table was very high. The sand mound was always considered as a more expensive and complicated sand mound septic system.
The way a sand mound works was still pretty much like an ordinary septic system with a few exceptions. It also has a tank for collecting the wastewater that your household produced. In the tank, anaerobic bacteria still breaks down the solid waste materials that settles at its bottom, allowing the clear effluent to be dispersed into the sand filter and into the bio-mat for further purification before heading out into the drain field. This is done before the treated wastewater gets absorbed in to the soil absorption system and into the water table to be used again in the surrounding environment. It has similar components as a conventional septic system but are all modified. As you can see, it was a system that is meant to be raised above the surface, hence the mound structure. Because it is a mound structure to begin with, the sand mound system has been always known to be a wastewater treatment system that is exposed to the various changes in the environment, particularly to the changes in the weather. The sand mound should be well-protected from the elements, especially from the cold weather. Usually, it is mandatory for a construction fabric to be installed before placing the top soil layer of the sand mound. This keeps the entire sand mound system warm and running even in freezing weather.
You were always very vigilant in taking good care of your sand mound and your yard. It was a new thing for you to see dead grass over the sand mound. You didn’t have that several months after the installation of your sand mound system. The septic expert told you that they only placed a thin layer of soil over your sand mound. This didn’t retain that much water as the rest or the soil in your yard because the aerobic bacteria were prioritized in this area. The aerobic bacteria need a high level of oxygen in the soil. If the soil is soggy, there is less oxygen and this would deplete the amount of aerobic bacteria that will purify the pre-treated effluent in the soil absorption system. The purification process should always be maintained in your sand mound system so that contamination would not happen. If the effluent still has the pathogens and pollutants when it gets distributed back into the environment, you could expect harmful effects to the surrounding water systems in your area.
Your septic expert instructed you not to water the dead grass over your sand mound because this will make it had for the soil absorption system to take in the pre-treated wastewater. It will then back up into your home and onto your yard. The soil on the sand mound should not be made any thicker so that the effluent could easily evaporate and not be retained in the soil enough to lower the oxygen level. Both anaerobic bacteria and aerobic bacteria should be well cared for to make sure that the entire sand mound system runs efficiently from beginning to end.
Dead grass over the sand mound is a good thing because it is a sign that your sand mound system is functioning very well. It tells you that there are no leaks or slow drains. So even if dead grass could really put you off as a homeowner, you have to get used to this if it is on your sand mound. It would definitely be more of a compliment for you to have the dead grass because to the trained eye, it would always mean that you are very responsible in maintaining and caring for your sand mound system.