If you’re thinking about tile drainage on a farm, the first step isn’t picking pipe size. It’s getting a topo survey. This gives you real elevation numbers for your field instead of guesses. And in a state where many fields are nearly flat, those numbers matter a lot.
Find the Elevation Changes That Control Drainage
Water moves because of grade. Not because a field “looks” like it slopes one way.
A topo survey shows you the real story:
- Where the field rises and where it falls
- Which spots have almost no elevation change at all
- Where grade might run out before the water gets where it needs to go
- How the field’s high and low points line up with a proposed outlet
This matters more in North Dakota than in hillier states. Some agricultural fields here are extremely flat. NDSU points out that a tile line running at a 0.1% grade only drops about 1 foot over 1,000 feet. That’s a small number. But it’s the difference between water that drains and water that sits.
Without survey data, you’re planning a drainage system on assumptions. With it, you’re planning on facts.
Check Whether the Field Can Reach Its Intended Outlet
A drainage system only works if the water has somewhere to go. This section isn’t about pipe layout. It’s about the outlet itself.
A topo survey helps answer:
- Is there an existing ditch or waterway nearby that can receive the water?
- What’s the elevation at that outlet point?
- How much fall is actually available between the field and the outlet?
- Are there sections where gravity flow looks difficult?
- Does a pumped outlet need to be looked at?
NDSU explains that when the topography or the ditch elevation won’t allow a gravity outlet, a pump may need to be considered.
A topo survey doesn’t decide whether you’ll need a pump. It gives you the elevation numbers. An engineer or drainage professional uses those numbers to make that call.
Identify Low Areas That Need More Than a Fieldwide Assumption
It’s tempting to look at a field and say, “It slopes this way, so drainage should work like that everywhere.” That’s rarely true.
A single grade estimate for an entire field can hide a lot. A detailed elevation dataset shows things a general assumption misses:
- Small depressions that hold water
- Subtle grade shifts across the field
- Spots where drainage patterns don’t match the rest of the field
- Trouble areas near field edges
- Elevation changes near ditches and waterways
North Dakota NRCS guidance notes something specific here: on very flat fields, onsite GPS measurements can be more accurate than some electronic elevation data. That’s a useful point. It means the level of detail in your survey should match how flat and how sensitive your field actually is. A rough estimate might be fine for one field and completely inadequate for another.
Give the Drainage Designer Field-Specific Elevation Data
Once the survey is done, the real work starts, handing that data to someone who can use it.
A drainage designer or engineer works with survey data to look at:
- Existing ground elevations across the field
- Where drainage routes could run
- Elevation at the outlet
- Profiles and grade along proposed lines
- How different parts of the field drain
- Spots that need a closer look before design moves forward
NRCS planning guidance for North Dakota recommends profile and cross-section surveying when a project needs enough detail to check waterway feasibility and design.
The survey supplies the measurements. The drainage professional turns those measurements into a working system. Those are two separate steps, and both matter.
Verify the Survey Before the Tile Plan Moves Forward
Before any tile plan moves past the drawing stage, it’s worth checking the survey itself. A few gaps here can cause problems later.
Confirm the following:
- The survey covers the whole drainage area involved in the project, not just part of it
- The intended outlet is included in the survey
- Nearby ditches and waterways are documented
- All the elevation points the design needs are actually there
- The survey’s accuracy fits the project. A rough survey won’t cut it for a tight-grade field
- Regulatory or environmental review needs are checked before any construction starts
North Dakota NRCS points users toward current state drainage rules and regulatory information. A topo survey is a planning tool. It’s not a permit, and it doesn’t clear a project for construction on its own.
