I believe that pit run is commonly used for backfilling in this area. This consists of a mix of sand and many different sizes of gravel. I was thinking about the footing drains, and how it seems like you don't want fines above the drain pipe because it will tend to cause the fabric over time. Is pit run then the wrong choice for backfilling? Would a different product be better? Thanks.

I would think that the sand would be no problem--it's the finer silt in clay that clogs fabric. But I'm not a real expert on this.

I'm not an expert either, but think what you describe as pit run is not suitable for the purpose stated. Different size gravel combined with sand (we call it "road mix" out here) is used because it compacts so well; something you would want to avoid when the purpose is to allow water to percolate down to the drain. Might depend on how big your different sizes are. Suspect a washed, rounded, uniform sized stone is a better choice.

A uniformed sized stone does not compact well (think of a jar full of marbles) and creates voids for the free flow of liquid water.

you want washed stone around the drain tile. Sand or gravel - and "pit run" - what we call "bank run" might work, but if it has too many "fines" - they can clog the drain. The problem is that you won't find out for a while, and by then you'll have flowers and bushes planted and you won't want to dig it up. Washed stone is a little more expensive - not much - but it works. Not a place to cut corners. Also, use White hard PVC drain tile - do NOT use the black "slinky" stuff - that crushes easily. Again - do it right & you'll have no problems.

Also, even if you have great footing drains, still use overhangs, ground slope, gutters, etc to minimize flow through them. Other things being equal, less water through the drains = less clogging.