Here in my area, Lowes has them, but so does most lumber yards and bigger feed supply/ farm fencing places. Lowes keeps them in stock out in there Garden area where they keep fencing supplies and 20 foot lengths of PVC pipe. Their prices are fair, but I've found that if I tell the owner of the farm fence and supply place what it's selling for at Lowes, he will sell to me for ten bucks less.
https://www.lowes.com/pd/ADS-15-in-x-20-ft-Corrugated-Culvert-Pipe/3526584
$262 is what they are listing one for at Lowes.
Well I will be a monkey's uncle. My closest Lowes doesn't have it, but about 20 miles away, they have 4 in stock of both the 12 and 15". You know the crazy thing? Go to Lowes and set you location to Gaffney, SC (29341). Now, go to the top and search "culvert". It will NOT find that pipe. In fact, I can't find that pipe any way on the Lowes sites without your direct link to it. Now that; right there, is some real first class IT work. I've never seen that happen before where there's "hidden items" that you can't see based on your geo.
Well, anyway, Lowes has it. 250 bucks for a 20ft 15in. That's not exactly cheap, but, I only need one, so, not worth running all over creation to find it. I saw a lot of people recommending double wall, this says it is, but I assume, looking at it, it should be smooth on the inside (instead of corregated) right? I could see where smooth would be MUCH better for this type of application.
https://www.lowes.com/pd/ADS-15-in-...5405&cjevent=752333981abb11e98154000a0a240611
And, to the poster who suggested Ferguson, that was my first guess too. Went to their website, searched for culvert, not a single hit. Since my experience with this Lowes thing above, I tried something new, Googled for it instead of searching directly on their site. Yup, apparently they have it too. Nuts! It's not like "culvert" is a common term that's returning too many hits here people. How can typing in what it actually is; it's trade name, not return a hit on Lowes or Ferguson's website?