Alternating Leach Beds

[MasterPlumbersKeymaster]

Several years ago we had a beehive seepage pit installed to replace a saturated leach field. The pit is now evidencing problems (surface saturation).

In March, John Aldrich recommended
alternating leech fields. I would like to try this, but can’t find a source for a 4 inch diversion valve. Can Mr. Aldrich or someone else help me?

[John Aldrich1Participant]

Eric, I use a 4 inch, plug type valve manufactured by National Diversified Sales, a California company. Sorry I can’t remember the name of the city they are in, but I believe they have a World Wide Web page. I purchase the valves from a local plumbing supply store, RNR Supply of Fort Collins, Colorado (a GREAT Plumbing Supply Store). I use 1.5 inch plastic ball valves on pressure effluent systems.

The NDS valve costs about $70.00, and you must also purchase 3 Sewer and Drain couplings to place on the inlet, and 2 outlets. The molded pipe connections on the valve are male, beveled fittings, and will not fit inside of the SDR-35, PVC pipe that I use. If the thin wall PVC pipe is used for this connection, the contact area for the cement is only about 1/8 of an inch. This connection is destined to fail.

Drive the coupling over the entire molded fitting, and the cement contact area is increased to about 3/4 of an inch. The SDR-35, PVC pipe will then slip into the other end of the coupling.

The valve body is made of Schedule 40, PVC, or ABS Black plastic. I use the PVC valve. The entire valve is about 30 inches tall, and the valve body consists of 6 inch, Schedule 40, PVC pipe. It comes with a 6 inch cap. I always protect the valve cover with the use of a 10 inch round irrigation valve box. The valve box cover at the surface of the ground, allows easy access to the plug inside of the valve for the annual switching of the effluent flow from one leach field to the other. The plug inside the valve body is made of blowmolded Polyethylene. When you see the valve, the method of operation becomes evident.

When I first started designing alternating leach fields, 25 years ago, I used “Bullrun Valves” in my systems. The Bullrun Valve also has male, beveled fittings, but these valves cannot be modified to accept the SDR-35, PVC pipe, at least that was the case 25 years ago. I had a great deal of difficulty with these valves, with the installation process, with the poor performance of the valve, and with the replacement of the valve. The PVC plastic key became brittle, and snapped off when the client turned the valve the first or second time. I replaced every one of these valves with the NDS Valve, with a great deal of difficulty.

I suggest that the annual, septic system maintenance duties be performed on July 4th, “SEWAGE INDEPENDENCE DAY”. Celebrate your independence of the “Sewer Grid”, but remember that with this independence comes the responsibility of a sewage treatment system operator. JWA

[John Aldrich1Participant]

Eric, in order for the alternating leach field concept to be most effective, it is necessary to ventilate both leach fields.

Oxygen is the key to leach field recovery, and the oxygen content of the air 2 or 3 feet below the surface is less than 10%. The oxygen content of atmospheric air is 21%.

There are many ways to accomplish the ventilation port installation, and the best way is dependent upon the specific design of your leach field. If you have a question as to how to accomplish this installation, please send me an e-mail message. JWA

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