Manhattan, Kansas: what the ground under the city is like
Manhattan sits in Riley County, on flint hills and osage cuestas. The soil mapped here is predominantly classified well drained — and that classification, not the rainfall total, is what decides how a basement behaves.
34% of the mapped soil area around Manhattan is wet enough that the USDA describes it as needing artificial drainage.
Linear extensibility 10.6% — very high.
Shallowest annual water table around 160 cm (5.2 ft).
Values are for Riley County, which is what the soil survey resolves to. Full county report · soil map for a specific address.
The ground under Manhattan
Flint Hills and Osage Cuestas. Residuum from Permian limestone and chert on the hills, with expansive clays from Permian and Pennsylvanian shales in the valleys and to the east
One of the most expansive soil belts east of the Rockies. Foundation cracks occur here in houses with faultless drainage, because the cause is not water in the basement but volume change in the clay under the footing.
When it shows up here
| Water | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ground movement | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
The mechanism here is the wet–dry cycle, and it peaks in the summer drought: clay shrinks hard from June to September, then the first heavy rain swells it back. Foundation cracks tend to appear at the ends of that swing, not during it.
Climate pattern for this physiographic region, not a forecast for your house and not from the soil survey. It answers a question homeowners actually ask: when does this show up.
What repairs cost in Kansas
| Reference job | Modelled range |
|---|---|
| Interior drain along two walls + sump pump | $4,550–$9,750 |
| Exterior excavation of one 40 ft wall | $3,400–$9,700 |
| Underpinning on 10 piers | $13,500–$28,800 |
Regional factor for KS: ×0.90. Full cost breakdown for Kansas · run your own dimensions.
ZIP codes in Manhattan
66502, 66503, 66505, 66506
Soil does not stop at a city boundary, and neither does this data — every ZIP code above resolves to the same county soil survey. For the individual survey polygons around one address, use the soil map.
Questions about Manhattan
Is the soil the same everywhere in Manhattan?
No. These values describe Riley County as a whole, which is the unit the soil survey publishes. Within a city, map units change over a few hundred metres — the soil map draws the actual polygons around a point and is the honest answer for one address.
Which contractor should I call in Manhattan?
We do not rank or recommend individual firms and we are not one. What this page is for is knowing which kind of work the ground here points to before anyone quotes you, and which claim to check. If you want quotes, the form below passes your request to the named networks.
Does this replace an inspection?
No. It tells you what the ground is; an inspection tells you what your building is doing on it. The useful order is: read this, print the brief for your county, then have someone look.
Get quotes in Manhattan
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