Try Washington Beach Mining.com(it may be one word) He has a Youtube channel worth watching. The guy there goes out frequently on the beach north of the jetty out from the river. (Benson Beach?, which I couldn't find on Google Maps) The area has access through the State Park then to the west, below the light house. I think he is usually digs on the beach closer to the washed up logs and debris. He uses a Gold Cube running into a sluice. All recirculating.

I was over there several years ago on Long Beach, knowing little. Dug in a spot where I could get fresh water from a very little stream across the beach.
Didn't find much of anything. The black sand is a *itch to pan if it is even possible. Too fine, too heavy, impossible to keep suspended in the pan water.

It might be good to take a small wagon or cart to haul your equipment.

Wayne
Pullman, WA

Access from state park, or I think it's 38th street about a mile up
North. Can drive all the way south to just below lighthouse. I think it's Benson cove but not sure.

You'll have to have gold and fish book and follow it. Thousands of tons of black sand, just have to find the pay layer. Wayne's right, tough processing, gold can be as fine as 600 mesh. Classify as far as you can.

Watched Mike Pung at the last gold show in Portland. He spent the time between the Tacoma and Portland shows there and was using that material for his demos. Cube is one of the better ways to go, but still going to be a bear to final pan, or miller table it.

If you're going to take a bucket home, just remember, 5 gal bucket is going to be over a hundred lbs to load in the rig.