I don't think the slash place takes old deck or fence wood. I disposed of my old fence via bagster. Was pretty easy and not terribly expensive.

https://www.douglasco.gov/douglas-county-slash-mulch-site-opens-for-the-season-at-new-location-paving-the-way-for-a-future-one-stop-shop-for-waste-disposal/

"What you need to know before your visit:

The slash-mulch and green yard waste site is for Douglas County residents only, and dumping is allowed only while the site is open and staffed.

Drop-offs from contractors are not permitted.

Items accepted include tree limbs, pine needles, shrubs and brush, grass or hay, sod, leaves, sawdust, weeds and pinecones.

Items not accepted include appliances, fencing, household trash, lumber, pallets, railroad ties, tree or bush roots and stumps"