Posted by John Aldrich on November 29, 1999 at 03:21:25:

In Reply to: Sandmound drain systems posted by Duwayne Graves on November 28, 1999 at 09:37:59:

: I have a sandmound system that needs some attention and I am not sure what to do. It is not excepting the gray water that is pumped out to it so I have decided to either rebuild or replace it. The only reason I have to have a sandmound system is because my land won't " perk" can someone please tell me on show me the plans on a sandmound system so at least I know what I am dealing with. To replace the sand in the system is 4 grand alone!!!! I don't have that kind of money right now but if someone in Clark county needs firewood I can give them plenty if they would just fix my sandmound. Of course you would need a backhoe and a dump truck to bring in sand to rebuild the mound. Thanks and I hope to hear from someone. " all wet and mad " Duwayne

Duwayne, you have been "all wet and mad" before, so just relax. If we lived in a perfect world, you could simply go to the Clark County Health Department office, and obtain an as-built plan of your entire septic system. Unfortunately, the sad fact is that most septic systems installed in the United States of America, and all other countries of the world, lack this important documentation.

The nature of individual on-site septic systems is such that every system is designed, and constructed differently, so it is impossible to find a set of accurate plans for one specific system, unless the installer has prepared a set of as-builts, and has submitted them to the Health Department. Also, it is an inherent design characteristic for a single leach field, or sand mound to fail. To not design for this inevitability by utilizing alternation of effluent flow into two fields, is foolish. The alternation of flow is an annual event to be performed manually by simply turning valves.

I will assume that what you are calling
"gray water", is in reality, septic tank effluent. The water may appear to be gray, but if it contains water from the toilet, it is called "black water", or septic tank effluent.

The reason the sand mound no longer accepts the effluent is because a biological clogging mat has formed over the surface of sand. This clogging mat is what controls the percolation rate of the effluent in the sand mound. The nutrients, and suspended solids, that are pumped from your septic tank with the effluent, are what "feeds" the anaerobic microbial slimes and organisms which constitute the clogging mat. The thicker the clogging mat becomes, the less permeable it becomes. At some point in time, the percolation rate of the effluent through the clogging mat is less than the application rate over it. When this occurs, the water surfaces, and in the case of a mound system, spills down the slope of the mound.

I believe the most immediate, and cost effective "fix" for your system is to contact BACTERIA CONCEPTS, INC., and obtain one of their microbial innoculants which is specifically formulated to reduce the clogging mat in the sand mound. Bacteria Concepts, Inc. has posted responses to several inquiries on this Bulliten Board, and their information can be found here.

Additionally, I think it would be prudent to install a GAG SIM/TECH FILTER, in the discharge port of the sewage effluent pump in the septic tank, or pumping pit. This filter will significantly reduce the suspended solids in the effluent being applied to the sand mound. Reducing the "food" supply for the critters that constitute the clogging mat will reduce the thickness of the mat, and therefor improve permeability of the effluent through it. The filter costs about $350, but is well worth the expense if you can avoid the expense of a new sand mound. Be sure to provide a riser from the pumping pit to the ground surface in order to allow easy access to the pump and filter for maintenance.

If these less expensive "fixes" fail to solve your problem, and installation of another sand mound is necessary, plans can be obtained on the Internet. Check with the National Small Flows Clearinghouse web page, and the links provided on that page, to find some plans that would be appropriate for your situation. If another sand mound is to be installed, install it next to the original mound, and place diversion valves, and a vacuum breaker valve, so that you can have the ability to alternate the flow annually, from one sand mound to the other.
When the effluent flow is stopped in the resting sand mound, the critters that constitute the clogging mat are starved to death.

The vacuum breaker valve prevents the potential of syphoning of the pumped effluent back into the pumping pit. In climates where freezing temperatures are a design issue, the vacuum breaker allows for the effluent to drain from the pressure effluent pipe back to the pumping pit.

An operation manual should be produced for your system, no matter what course of action you take. The manual should contain a description of the system, photographs of whatever construction you decide on, and an as-built plan. Also include a maintenance log, and enter the each maintenance procedure performed. This manual will become an invaluable document for you, and future owners of the system.

If a repair permit to accomplish this work is required by the local regulatory agency, I recommend that you obtain one. The Health Department personnel may be of some assistance in the design of a new sand mound if you have to go that extent. In which State is Clark County located? Please respond by e-mail to let me know what course of action you plan to take. I don't need any firewood. JWA

Replies:

• Re: Sandmound drain systems Duwayne 02:10:19 12/01/99 (0)