Letter to the Editor: Expanding upon installing gravelless systems

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I thoroughly enjoy reading Jim Anderson’s column “Septic System Answer Man” each month in Pumper magazine. Jim has great experience, is very insightful and always covers a large range of topics. One of Jim’s online articles entitled “Everything You need to Know About Installing Gravelless Systems” hits close to home for me being employed by a gravelless system manufacturer. My job puts me in contact with installers across North America. Therefore, I wanted to expand upon Jim’s article.

Chambers and other gravelless products have become the new de facto “conventional technology” in nearly all states and provinces. Last year most of the soil infiltration systems installed in North America used gravelless products. Codes vary dramatically state to state and county to county. This results in gravelless products being installed in many different types of installations including clay, silt, and sand soil types, deep and shallow systems, mounds, at-grades, fill systems, pressurized systems, gravity systems, serial distribution, d-boxes, trenches, beds, residential, commercial, sand filters, and evapotranspiration systems, from Mexico and the Caribbean to Alaska and the Yukon Territory. You get the idea: every conceivable location, soil condition, and installation type.

The article appropriately starts off with the heading, “There are many advantages to gravelless systems, but they need to be installed with care.” I couldn’t agree more, as care is required for any type of system, not only gravelless. As Jim goes on to state, “In all cases, from an installation standpoint the same rules or principles for rock-filled trenches or beds apply.” One of my favorite educational points to make as I give presentations nationally is that, “Chambers are not a magic box.” The chambers (or any system type) do not treat wastewater nor do they infiltrate wastewater; the soil does. Therefore, as with any onsite wastewater system it is important to protect the soil interface during installation. The soil is our work horse.

Jim states that sand is usually placed around the chambers to ensure that they stay in place during backfill. This is not the norm in the U.S. and Canada; by far the most common installation is to backfill with native soil unless otherwise specified by design.

Gophers have been a very limited issue, as we receive about a half dozen calls per year. Installation guidance is available for “gopher prone” areas as Jim has pointed out utilizing chicken wire. Once the system receives wastewater, the gophers will no longer be interested.

Please note that if you have questions about gravelless products or installation guidelines you should contact your gravelless manufacturer. Our goal is the same as yours: to provide a quality, properly installed system and to protect public health.

Dennis F. Hallahan, P.E., Technical Director, Infiltrator Water Technologies


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