Introduction
Sewer and water line work is one of those projects where the details matter enormously. A trench dug to the wrong depth, improperly compacted backfill, or a line installed without accounting for frost can mean a failed system within the first few years and a dig-it-up-and-start-over repair bill.
We do a lot of utility excavation work across Brookings County and the surrounding region, for new construction, replacements, and repairs. Here are the five things every property owner should understand before that first trench goes in.
1. Frost Depth Determines Everything
In South Dakota, the ground freezes. How deep it freezes varies by location, year, and soil type, but in Brookings County we plan for a frost depth of approximately 60 inches. Any water line that runs above the frost line is a freeze-up waiting to happen.
Sewer lines are not pressurized, so they do not freeze the same way water lines do, but they still need to be deep enough to maintain proper slope and to protect them from frost movement in the surrounding soil. Getting the depth right at the start is not negotiable. Digging shallow to save time creates a repair project that will happen in the coldest part of winter.
2. Utility Location Comes Before The First Mark
Before we dig anything, we call 811 and get a full utility locate done on the property. This is the law, and it is common sense. In older rural properties and in developed areas that have been built up over decades, there are often utilities in unexpected places: old phone lines, abandoned water services, private electrical runs, and propane supply lines that were never fully documented.
We also look for private utilities that 811 does not cover. Knowing where a neighbor’s waterline crosses the property or where a private irrigation system runs can save a very expensive surprise mid-project.
