Checking soils before buying land

By
June 14, 2023

Soils testing

Woohoo! You've located that perfect piece of property outside of town to build your next home on.

Or you've found some great hunting land and would like to build a weekend getaway cabin?

Maybe you're ready to invest in a prime development property and subdivide it for a profit in a few years...

It's time to make an offer before the opportunity slips away and BOOM! Your offer is accepted and you're under contract. Time to focus on performing your due diligence.

So what's first? Well, you could say it's #1 and #2... making sure the soils are suitable for a septic tank.

What makes a septic tank appealing is that it can be installed in a location further away from cities and towns and doesn't come with a monthly payment like city sewer. As long as you don't pour that bacon grease from breakfast down the drain, a septic tank requires some minimal maintenance every few years and is a cost-effective option for managing your wastewater treatment.

But before you can even think of installing one, you have to test the soil on the property to determine if the wastewater the septic tank produces can be accepted, treated, and dispersed into a drain field area. Otherwise, you'll have a nasty mess of untreated effluent (i.e. sewage) pooling up near your home.

Here in Coastal North Carolina, we are fortunate to have plenty of deep sand ridges and not many steep slopes which means conventional septic tanks can be utilized. The trade-off is that some properties have a high water table which requires more advanced septic systems, using technology like anaerobic drip to make up for the lack of deep sand. That means your costs go up significantly and your system will require an operator to maintain it. Not ideal by any means.

That brings me into how you can begin your soils analysis by starting with a review of the county GIS map for the property you're considering buying.

Typically, the GIS website (or tax map website as some call it) will have overlays or layers that can show what kind of soils are on the property. Some counties will be much more helpful than others by actually describing the soil in detail instead of just providing an abbreviated name.

For example, you pull up the property and see that most of the soils are Murville Mucky Fine Sand - which sounds as bad as it actually is. You can usually type in whatever the soil type is in a google search and see if it's a "poorly drained soil located in floodplains". Now that doesn't sound like a good place to put a septic tank or a home does it?


While looking at the GIS soils reports can be helpful, don't fully trust them either. I've been very excited after finding a tract with tons of Baymeade, a fine sand that drains very well and usually is a slam dunk for septic tanks. But when I visited the property and dug some holes myself, I was heartbroken when I hit the water table less than a foot below the Baymeade in several locations.

That's why visiting the property and digging some holes is the next important step. I have a hand auger which allows me to twist the sharp edges into the ground and pull up "plugs" of soil about 6 inches deep at a time. Each time I pull a plug up, I rotate the end to face me so I can take a good look at the dirt and rub it between my fingers to feel the texture.

You're looking for coarse, dry grains of light sand and maybe some gravel mixed in - not dark sticky stuff that is wet like clay. The sand can be slightly damp and form clumps but should easily break apart in your fingers. A lot of times if I dig two or three times and I hear a suction sound or the end of the auger sticks, I stop right there. As my Dad likes to say when we hear that lovely sound, "I've seen enough". We know septic tanks will not work and it's time to head out.

If the dirt is looking good, I carefully shake out the soil after inspecting it a couple times and try to create a fan-like pattern on the ground to paint a picture of what the layers look like. A general rule of thumb is you want anywhere between 24" to 48" of a sand layer but it really depends on whether you're after one system for your home/cabin out in the woods or a large drain field area to support a subdivision.



If the dirt is looking good, I carefully shake out the soil after inspecting it a couple times and try to create a fan-like pattern on the ground to paint a picture of what the layers look like. A general rule of thumb is you want anywhere between 24" to 48" of a sand layer but it really depends on whether you're after one system for your home/cabin out in the woods or a large drain field area to support a subdivision.


Something else that is helpful is to pay attention to the vegetation around. If you notice that there are mostly mature trees spaced out with open ground cover and not much "scrub" brush, that can be indicative of good soil. Anytime you're faced with dense brush that's not very tall and packed together it's probably a sign of a high water table aka wet soils. The lay of the land can have some sloping contours but numerous depressions or low pockets scattered about mean the dirt will experience ponding and not allow water to escape quickly.

With all this being said, I'd like to make a disclaimer that I'm not a licensed soils scientist and you should certainly consult one before purchasing a property as each piece of land is unique and conditions vary considerably. These tips are a product of my own investigations and the privilege of working for my father who has graciously shared decades of experience with me from working in the development and timberland industries.

It's my hope that as your agent you can feel confident with my preliminary assessment of either the property you're considering purchasing or would like to sell before spending your hard earned coin on professional services. Thank you for taking the time to read this article and please reach out to me when you're ready to participate in the real estate market!