How to Regrade Soil Toward Drain Spout to Prevent Water Seepage Under House?

My partner and I bought our first home a few months ago, and we’re still learning the ropes. During the last rainy season, we discovered standing water beneath the house. The entire backyard—including the pool deck—slopes toward a low corner right at the foundation.

I dug around and uncovered a clogged drain spout (the yellow-vented pipe in the photo). The top of the spout sits higher than the surrounding soil, and when I spray the area with a hose, the dirt just soaks up water like a sponge instead of channeling it into the drain pipe.

What’s the best way to regrade the soil so water naturally flows into that drain spout and doesn’t seep under the house? I’d love tips on proper slope angle, soil amendments, or any additional drainage solutions you’ve found effective.

Thanks in advance for your advice!