The ability to assess the soil treatment area or drainfield is an important part of system management
One major component of onsite system management is providing the ability to assess whether the soil treatment area or drainfield is accepting the effluent delivered. Many regulatory management programs require inspection ports in drainfield trenches or beds.
From a system management standpoint, this allows a quick way to see whether effluent is ponded in the system and what proportion of the system is being used. A number of years back, I remember recommending inspection ports in trenches. Some of the first installations resulted in what I would term “unsecured” inspection ports. They were easily extracted from the trench the first time the push-on cap was removed, rendering them useless.
The following are some guidelines for locating and securing inspection ports. They can be installed at both ends of the trench or bed. The pipe should extend to the bottom of the trench or bed. Holes should be drilled in the pipe up to the level of the top of the trench or bed. The pipe should extend from the top of the system to the ground surface or above. It should not be connected to distribution piping.
Many homeowners object to a bunch of pipes sticking above ground and they also seem to draw riding lawn mowers like magnets. An effective way to provide access is to bring them into a valve box at the surface. That way they are easily found and identifiable. Caps on the pipe should be screw-type. If slip or push-on caps are used, they should be slit on the side to allow easy removal.
There are three primary ways the inspection ports can be secured in rock systems. They can be anchored using a 12- to 18-inch section of rebar, a pipe tee created at the bottom of the pipe, or using and anchoring a toilet flange at the bottom of the pipe. The goal is to securely anchor the inspection port so it does not move around or get accidently removed when accessed. It also ensures a consistent measurement of liquid depth.
For chamber systems, the pipe is attached to the chamber at the port location provided with stainless steel screws. In the chamber, the pipe extends to the infiltrative surface and is perforated to allow an accurate measure of liquid depth. For any proprietary products, remember to follow the manufacturer’s instructions.
About the author
Jim Anderson is connected with the University of Minnesota onsite wastewater treatment education program and is an emeritus professor in the university’s Department of Soil Water and Climate. Send him questions about septic system maintenance and operation by email to firstname.lastname@example.org.