Trenching for new sewer lines

With the spread footings excavated, we now can finalize how exactly to route the sewer lines through the basement. But first we need to remove the old vitrified clay tile sewer, which we traced and exposed a while ago.

We start with the excavation for the new sewer at the connection to the existing sewer, i.e. where the existing sewer comes into the building. The elevation of the existing sewer is something we cannot change, and is thus the logical starting point.

While trenching through the basement, we make sure that the bottom of the trench steadily rises at a slope of about 2% (or about a ΒΌ inch over 1 foot). The slope is needed for proper waste water flow out of the building. Paying attention to and finishing the trench invert with the correct slope will make the upcoming sewer installation a whole lot easier.

Trenching for the main lines (storm and sanitary) is straightforward. Figuring out the trenching for the check valve and all basement plumbing is like shooting from the hip. It is difficult to finalize until we have all the tees, wyes, bends, and vents actually laid out.

I gave it my best bet and hoped most of it would fit the plumbing, although we may need to excavate some more during the sewer installation.

About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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