Leech field covered by pool!

rimmm, your existing leach field will fail at some future date, but the lack of evaporation is just one of the factors that will contribute to the failure. Other factors that contribute to leach field failure are organic overloading caused by typically poor primary treatment of the sewage, the migration of small soil particles into the voids between the gravel (siltation), and the natural increase in the thickness of the clogging mat that forms at the soil/gravel interface.

“He advised me to install an additional leech field on my lot through a secondary “D” box. Is he correct?”

Yes and No! The installation of an additional leach field is sound advice, however, instead of a “secondary” D box, a diversion valve should be installed so that the system will then be an alternating leach field system. I suggest that the existing leach field be abandoned.

If you decide to have the leach field replaced, consider installing 2-half sized leach fields equipped with a 4-inch, NDS brand diversion valve. Cover the valve riser with a 10-inch round irrigation valve box to allow for easy access. The top of the box is set at the final grade elevation. The valve will allow the alternation of flow to the fields. Use half the field for 1-year while the other half rests. Turn the valve annually on the 4th of July, SEWAGE INDEPENDENCE DAY. Celebrate your independence of the sewer grid, and remember that with this independence comes the responsibility of a sewage treatment system operator.

I recommend the use of plastic leach field chambers such as the ADS Bio-Diffuser, or Infiltrator brand. Cover each chamber leach field with a 4-foot wide sheet of geotextile fabric (landscaping fabric). The geotextile will prevent the migration of silt into the void under the chambers. The fabric also acts as a wick, wicking by capillary attraction the effluent up over the chamber units, and then into the soil. This will enhance the evaporation capacity of the system.

Install 4-inch monitoring and ventilation ports to the ground surface on each end of each field. The 4-PVC risers are covered with plastic 6-inch round irrigation valve boxes. The tops of the irrigation valve boxes are set at the final grade elevation. The boxes will allow easy location, easy access, and you can run the lawn mower right over them. Typically the covers of the boxes are green.

The tops of the in-use field monitoring ports are fitted with 4-inch female threaded adapters, and threaded plugs to prevent sewer gas odors from emanating into the yard. The tops of the resting field ventilation ports are fitted with 4-inch female adapters, and plastic drain grates.

The ventilation ports will allow atmospheric oxygen to enter the resting leach field, and this will create an aerobic condition in the resting leach field. The oxygen will oxidize the Ferric sulfide (that black slimy crap), a major component of the clogging mat. Also, the aerobic condition will allow the aerobic microbes, present in the surrounding soil, to migrate to the clogging mat and consume the organic matter constituent of the clogging mat, and consume the dead bodies of all their anaerobic microbial cousins. Exchange the solid threaded plugs with the drain grates when the valve is turned on SEWAGE INDEPENDENCE DAY.

While you are involved with the major renovation of your septic system, I recommend that 20-inch plastic risers be installed over the inlet manhole, and the outlet manhole of the septic tank. The covers of the risers should be at the final grade elevation to allow easy access to the tank. Let’s face it, if you must excavate the soil over the septic tank manhole with a shovel, chances are that this chore will be avoided. I use Tuf-Tite brand risers.

I also recommend that the outlet tee of the tank be fitted with a septic tank effluent filter. The brand that I use is manufactured by the Tuf-Tite company, although there are several other high quality filters on the market. The filter will reduce the organic matter in the effluent from flowing into the leach field. Clean the filter annually on SEWAGE INDEPENDENCE DAY.

Another chore that should be performed annually is the measurement of the sludge accumulation in the primary chamber of the septic tank. The sludge can be measured with a “SLUDGE JUDGE.” Do an Internet search to obtain this neat device. I recommend the implementation of the “1/3 RULE” of sludge removal. When the level of the sludge is 1/3 the total liquid depth of the septic tank, it is time to remove it.

The final chore to be performed on SEWAGE INDEPENDENCE DAY is to record all of the maintenance performed on the system in a maintenance log. I prepare a SEWERS CAN BE BEAUTIFUL operation manual for each of the septic systems that I install for my clients. The manual contains a description of the system design, photos of the system components, an as-built plan, a description of the required maintenance procedures, a copy of the permit, and the maintenance log. The manual becomes an excellent sales tool when the time comes to sell the home. The manual answers all questions a potential buyer may have regarding the performance of the septic system, and will allay the fears typically encountered when purchasing a home served by a septic system.

“How much would an secondary leech field cost to install?”

Depending upon the required leach field area, the above described leach field installation would cost in the range of $2,000 to $4,000 US. The system that the technician is anticipating installing would probably cost less, but you get what you pay for. The installation costs of leach fields vary depending upon your geographical location. The estimate of cost given is the cost of a system capable of serving a 3-bedroom home located in Larimer County Colorado USA.

Well rimmm, I had better end this lengthy diatribe. If all soil absorption type septic systems were designed and constructed to the above standards, then there would be far fewer failed septic systems. Maintenance is the key to successful septic systems. However, if the required maintenance is difficult, or impossible, then chances are it will not be performed. If you would like photos of my typical standard system, send me your e-mail address. My address is [email protected]

Incidently, a “leech” is a blood sucking aquatic worm. A “leach” field allows for septic tank effluent to leach into the soil. :>)

John Aldrich (Septic Tank Yank)
Septic System Consultant
Timnath, Colorado USA

» This message has been edited by John Aldrich on 01 May 2003

You could move the pool for less $$$’s

rimmm and Ken,

“You could move the pool for less $$$’s”

Perhaps this is true. Of course, it would depend on the size, and type of the pool as compared to the installed cost of the required size of the new leach field. If the pool is relocated, then the owner is still in possession of an inferior designed leach field which infact has a finite service life. I have not installed, nor ever owned a swimming pool, so I do not have the experience to estimate the cost of relocating one.

Now rimm, you need to provide more detailed information in regard to the size and type of pool that you have, the size of the leach field required, and the geographical location of your home on the globe.

My original response to this inquiry is quite lengthy, but unfortunately, it does not contain your list of options. So, here goes:

Option 1. Relocate the pool.
Option 2. Install the recommended new leach field.
Option 3. Do nothing.

If you would like to discuss the benefits and drawbacks of the 3 options, then respond on this Discussion Forum.

John Aldrich (Septic Tank Yank)

» This message has been edited by John Aldrich on 02 May 2003

Moving the pool is not an option. It is 18X33 and I built a deck 44X44 all the way around it last year (24 footings!). I live in Rhode Island. The additional leech field is my only choice as if I do nothing, impending doom will be looming. Thanks for the responses. You spent some time on them.