Drainage
in Mount Pleasant & Charleston

There's no price list here, on purpose: no two pieces of ground are the same. Josiah walks it and gives you a straight number. What it comes down to:

• Length of the run. How far the water has to be carried.
• Depth and outlet. How far it is to somewhere the water can actually leave.
• Materials. Pipe, stone, fabric and any catch basins.
• What's in the way. Fences, drives, beds and roots between the problem and the outlet.
• Putting it back. Restoring the lawn and beds the trench crosses.

Almost always the grade rather than the soil. The ground slopes so that water collects somewhere instead of leaving, and in the Lowcountry a high water table means it has nowhere to soak away to once it gets there.

Regrading the low areas so water runs off, and cutting drainage where the grade alone can't carry it. Which of the two does the work depends on how much fall there is to play with.

Usually a low pocket holding water long after the rest of the yard has drained, sometimes fed by a downspout or a neighbouring slope. Occasionally it is the water table sitting close to the surface, which is a different conversation.

A French drain to give the water a path out, or regrading to remove the pocket. Drainage here has to be planned around the high water table: a trench that fills from below solves nothing.

The grade falls the wrong way near the foundation. Common on older yards where beds have been topped up with soil and mulch over the years until the ground beside the house sits higher than it did.

Re-establishing fall away from the foundation, and drainage to carry water somewhere it can leave. This is the one worth looking at soonest: it's the problem that gets more expensive the longer it runs.

Usually because the water had nowhere to go. A drain needs an outlet lower than the problem, and with a high water table a trench dug too deep simply fills from below. Filter fabric matters too: without it, sandy soil washes into the stone and clogs it over time.

Not as concentrated runoff. Mount Pleasant's single-family stormwater guidance says runoff cannot be concentrated onto lower neighboring property, and downspouts cannot discharge within 10 feet of a shared property line. Drainage has to end somewhere it is allowed to: a ditch, a storm drain, or ground that can take it.