Retaining wall excavation around Wichita

Most of Wichita is flat, so retaining walls here tend to show up in a few specific places: beside a walkout basement, where a driveway or shop pad was cut into a rise, along a creek bank, and along a property line where one yard sits higher than the next. The block or stone is what people see. Whether the wall is still straight in ten years mostly comes down to the dirt work behind and under it.

What the excavation side of a wall includes

1. Locates. A wall trench runs along a yard, which is exactly where gas, electric, cable and fiber services cross. Kansas 811 needs at least two full working days, and digging within 24 inches of a mark is by hand. Sprinkler lines, landscape lighting and private lines to a shop or pool aren't marked, so show them to the crew.
2. Cut back the slope. The hillside is cut back far enough to leave room for the wall, the drainage zone behind it and, on taller walls, any reinforcing grid layers that extend back into the hill. That is usually a lot more dirt than people expect.
3. Haul it or reuse it. Clay cut from the slope rarely goes back behind the wall, because it holds water. It gets spread elsewhere on the lot or hauled off; see dirt work, fill dirt and hauling.
4. Dig and build the base. The base trench is dug into firm, undisturbed ground, then filled with compacted crushed rock so the first course sits level. The block manufacturer's installation guide sets how wide and deep the base is and how much of the first course is buried. A wall built on loose fill or soft wet clay is the one that leans.
5. Drainage stone and a pipe. Behind the block goes a zone of clean, free-draining stone, with a perforated pipe at the bottom that carries water out the ends of the wall or to an outlet. Filter fabric between the stone and the native clay keeps the stone from clogging.
6. Backfill in lifts and grade the top. Fill behind the drainage zone is placed and compacted in layers. The ground above the wall is shaped so surface water runs along or away from the wall rather than pouring over the top or soaking in right behind it.

Why drainage matters more in Sedgwick County clay

Much of the county's soil is clay that drains slowly and swells when it's wet. Behind a wall, wet clay pushes harder than dry ground, and water that can't get out builds pressure against the back of the block. That's why a wall in clay needs a real drainage path: free-draining stone, a pipe with somewhere to go, and a cap of less permeable dirt at the top so rain doesn't pour straight in. You can look up the soil on your own lot in the free USDA Web Soil Survey.

The pipe's outlet follows the same rules as any yard drain. Inside the City of Wichita, drain water can't be discharged onto the street, and aiming it at a neighbor just moves the problem. See French drains and where the water can legally go.

Does a retaining wall need a permit in Wichita?

For houses, Wichita and Sedgwick County use the 2018 International Residential Code with local amendments (Unified Building and Trade Code, Article 2, Section 4; the exemption is section 2.4.030, from Ordinance 50-833). Under it, a retaining wall does not need a building permit if it is 4 feet or less, measured from the bottom of the footing to the top of the wall, unless it supports a surcharge. A surcharge is extra weight above or behind the wall: a driveway, a parking pad, a building, or a slope that keeps rising behind it. Two things to keep in mind:

• The 4 feet includes the buried part. A wall that shows about 3 feet above the lawn can already be past 4 feet once the buried course and base are counted.
• Commercial property is stricter. The same code's commercial and existing-building sections only exempt walls up to 30 inches, measured from the lowest adjoining grade. For a shop on a business lot, a parking area or a church, plan on a permit. Either way, call MABCD at (316) 660-1840 with the wall's height and what sits above it, and see Do I need a permit?

Derby, Haysville and Andover run their own permit offices, so walls inside those cities go through them. See who issues permits in each Sedgwick County city.

Property lines, easements and floodplain

• Easements. Many Wichita subdivisions have drainage and utility easements along the back and side lot lines. A wall built across a drainage swale can back water up onto the lots upstream, and digging in an easement or the city right-of-way needs a City of Wichita permit.
• The property line. The cut-back behind a wall, and the base in front of it, take up more ground than the wall itself. If the wall is near the line, know where the line is before the dig, not after.
• Creek banks and floodplain. Excavating or filling in a mapped floodplain takes a floodplain development permit through MABCD. Check your lot on the Sedgwick County floodplain map.

Who builds it

Some landscape and hardscape companies do the whole wall, dig included. On bigger walls, especially ones cut into a walkout or a driveway, an excavation contractor often does the cut, haul and base trench and the wall builder follows. Either way, ask each bidder how deep the base goes, what stone goes behind the wall, where the drain pipe comes out, and where the cut dirt ends up. The answers tell you more than the price. When the wall is part of a bigger regrade or a walkout cut, one excavation contractor in Wichita doing the dirt side start to finish keeps the drainage and the wall base under one crew. See what drives excavation cost around Wichita and how to hire a Wichita excavation company.