Using Water Well Logs for Soil Data

So the last feature on the Michigan DEQ’s GeoWebface that I want to talk about for now is its well log viewer tool. The water well people probably find this feature useful for looking at pumping rates and water depths and whatever for comparison purposes, but I find it most useful for the soil descriptions that the drillers record on their well logs!

After looking at the regional geology in the bedrock and quaternary maps I posted about earlier, this is a great next step to drill down even more about what soils are out there and to get an even better sense of the soils that underly our county.

Here is an example – say you want to look at the soils on the east side of the county to get a sense of how thick or what type of soils (generally) were deposited in Glacial Lake Maumee.

I go to GeoWebface, turn on all well types and zoom in to the east side of Washtenaw County. Note: Page 11 of this link provides a description of the different well types in Michigan (e.g. Type I, II and III). I also turned on the Quaternary Geology overlay to show the types of soils that have been mapped at the surface here.

Well Face.PNG

I then click the “Identify” button above the map and start clicking on the green or red well blips on the map until I find something interesting (I can also box in a bunch of wells at once) and get a table of the wells. Once I do this, the left side of the screen changes to “Map Tools” and shows me this:

leftside

I can click on the “WELLID” and a PDF of the Well Log starts to download.  I see this screenshot of the Well Log (top half shown) when I click on the download:

Well Log.PNG

It’s a pretty incomplete log as far as well logs go but it does give me a general description of the soils encountered by the well drillers- lots of clay and then sand beneath it. This is a sequence of soils layers we would expect in a lake bottom with a calm, steady depositional environment. Not all water wells go to Bedrock so it’s also a plus from this one that they actually went that deep and that we know that bedrock here is at or around 140 feet below the ground surface.

Compare the above formation description with one from a well just a half mile west of there:

glacial-formation

There is a lot going on in just the first 60 feet below the surface – nothing like the thick layers of clay at all. Very likely something else was going on then sediment being dropped into a lake to give you all the different sands, clays and gravels.

So this is how you can use GeoWebface to look up public well logs and ultimately get some some sense of the soil beneath your feet! The DEQ has other tools out there to do the same thing (WellLogicthe Scanned Well Retrieval System) but none are as easy to use as GeoWebface!

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