Retaining Walls around Geneva Lake

Retaining walls on sloping and shoreline lots.

A retaining wall is a drainage structure that happens to be made of stone. Almost every failed wall failed because that was treated the other way round.

Ground around this lake slopes, and a good share of what we build exists to hold some of it still. Walls do that well when they are built as drainage structures and badly when they are built as stacked stone - and the difference is entirely behind the face, where nobody looks.

The rule that governs lakefront walls

It bites hardest on the north shore, where a great many Williams Bay lots fall away toward the water and the flattest ground sits inside the protected strip.

Before any engineering question there is a zoning one. Walworth County shoreland zoning defines the shore yard as the land within 75 feet of the ordinary high water mark, and retaining walls are named on the list of structures prohibited there - alongside patios, decks, fences, fire pits and hot tubs.

It goes further than that on slope specifically: a permit to change the grade within 75 feet of the water is generally not authorised, terracing is not permitted, and proposed land disturbance may not create level living space in the shore yard.

The practical consequence catches owners out, because the instinctive solution to a lakefront slope is to terrace it, and that is precisely what is unavailable exactly where the slope is steepest. What can usually be done sits further back, and the design problem becomes holding ground higher up the lot rather than near the water. More in retaining walls on shoreline lots.

Why walls actually fail

Almost never because the blocks or stones were wrong. The failures we are called to look at come down to the same few things:

• No drainage behind the wall. Water collects, freezes, expands, and pushes. A wall with nowhere for that water to go is a wall being levered forward every winter.
• No or inadequate base. A wall is only as level as what it started on.
• Backfill that holds water rather than draining it - often the excavated material put straight back in because it was there.
• Height without reinforcement. Past a certain height a wall needs geogrid or engineering, and the point at which that becomes true arrives sooner than people expect.
• Surface water aimed at it from a terrace or a downspout uphill.

What goes in behind the face

Drainage aggregate, a pipe with somewhere to discharge to, separation so the fill does not migrate into the drainage layer, and compaction in lifts rather than all at once. On taller walls, reinforcement extending back into the slope. None of it is visible in a photograph of a finished wall, and all of it is why one wall is fine at twenty years and its neighbour is leaning at six.

One tall wall or two short ones

Where the site allows it, stepping a slope in two shorter walls with a planted bench between is often better than one tall one - less load, less engineering, and a result that reads as landscape rather than as infrastructure. Where shoreland rules apply, the terracing option may simply not be available, which is another reason to settle the zoning question first.

Repairing a wall that has moved

A leaning or bulging wall is reporting a drainage or base problem. Rebuilding the face without addressing what is behind it produces a straight wall that leans again on the same schedule. We will tell you which you are facing before any work is agreed - see repair and rebuild.