Build a house out past the city sewer lines in Sedgwick County and the wastewater has to be handled on your own lot: a septic tank with a lateral field, a lagoon, or an advanced treatment system. Which one you get isn't really your choice. The county decides it from the soil, and the permit has to be in hand before the house permit is. This page covers how that goes, with a focus on the excavation side of the job.
Who permits septic systems here
MABCD regulates septic systems, lagoons and advanced systems in unincorporated Sedgwick County, according to its wastewater page. Key rules from that page:
- A licensed installer pulls the permit. Homeowners can't pull a wastewater permit, and every system has to be installed by a licensed wastewater installer. MABCD publishes a list of licensed wastewater contractors.
- Sewer first. A property within 400 feet of a public sewer has to connect to it; an on-site system there needs a variance.
- Wastewater permit before building permit. For new construction, MABCD issues the wastewater permit before it will issue the building permit.
- Repairs need permits too. MABCD's on-site wastewater fact sheet says any work on a system, from minor repairs to full reconstruction, needs a permit issued to a county-licensed installer.
Inside a city, the city's own rules and sewer come first, so check with city hall. Systems that discharge to surface water are a state matter: those need a permit from the Kansas Department of Health and Environment.
The soil decides: septic, lagoon or advanced system
Soil testing is required for new construction on every parcel. A qualified professional does it in the proposed system area, outside floodplains and easements, using boreholes and soil profiles; MABCD keeps a list of approved professionals and can waive the testing if adequate testing has already been done nearby. The result is a percolation rate, how many minutes it takes water to drop an inch in the soil:
| Perc rate | What MABCD points to | Notes |
|---|---|---|
| 0 to 60 minutes per inch | Septic tank and absorption field | Typically sandier soils; a higher level of treatment can be required where there are environmental concerns |
| Over 60 minutes per inch | Lagoon | Heavier clay soils; minimum lot size for a lagoon is 5 acres |
| Any soil, with environmental concerns | Advanced treatment system | Treats to a higher quality and disperses it into the soil under pressure; needs a recorded covenant and a service provider |
Much of Sedgwick County has heavy clay soils, which tend to perc slowly, while the sandier soils in the river valleys tend to perc faster. Older platted lots under 5 acres that won't perc may end up with a septic or alternative system instead of a lagoon. You can preview your lot's mapped soils on the USDA Web Soil Survey, but only the on-site test counts.
Tell us about the dig
(316) 869-0053What gets dug for a septic system
- Tank hole. A pit for the septic tank, set so the line from the house has enough fall, with risers brought up to grade so the tank can be pumped without digging.
- House sewer. A trench from the house to the tank at a steady slope.
- Absorption field. Lateral trenches in the tested area, laid out and sized to the soil results and the house, kept level so the effluent spreads evenly. The field should stay free of driveways, buildings and heavy traffic.
Every one of those cuts needs a Kansas 811 locate first. Rural lots still have buried electric, phone, fiber and rural water lines.
What gets dug for a lagoon
A lagoon is a bigger dirt job than a septic system: a shallow, bermed pond for the wastewater, with a septic tank ahead of it. MABCD's lagoon sizing, setbacks and construction standards sheet spells out the build:
- Standard sizes run from M-45 to M-65, about 2,126 to 4,436 square feet, with the interior slope at 3.5 to 1.
- A 1,000-gallon septic tank goes in line ahead of the lagoon, with risers to grade; a pressurized system needs a two-chamber tank.
- Bentonite is applied at half a pound per square foot to seal the bottom (1,100 to 2,200 pounds across those sizes).
- The interior berm is seeded and covered with erosion mat from top to bottom within 24 hours of construction.
- The fence sits 5 feet out from the outside bottom edge of the berm. Minimum distances to wells, foundations, property lines and surface water are on the same sheet.
The county applies the same standards to lagoon clean-outs. Once it's running, the county wants the berm grass under 6 inches, at least 3 feet of water depth, and no trees within 50 feet.
Questions to ask an installer
- Are you licensed by Sedgwick County as a wastewater installer, and will you pull the permit?
- Who does the soil testing, and what did the perc rate come out to?
- Does the price include the tank, risers, the house sewer, seeding and the lagoon fence?
- Where will the field or lagoon sit relative to the house pad, the well and future buildings?
The house pad, driveway and well usually come in the same build; see site prep and grading and dirt work and fill dirt, and the before you dig in Sedgwick County checklist. Call the number on this page and tell us about the lot, the house and where the system needs to go.
Common questions
Can I install my own septic system in Sedgwick County?
No. MABCD says homeowners can't pull a wastewater permit and every system must be installed by a licensed wastewater installer.
Septic or lagoon: who decides?
The soil. In unincorporated Sedgwick County a perc rate of 0 to 60 minutes per inch points to a septic system and over 60 to a lagoon, which needs at least 5 acres. Environmental concerns can require an advanced system in any soil.
Do I have to hook up to sewer instead?
If the property is within 400 feet of a public sewer, MABCD requires a connection; an on-site system there needs a variance.