Check out the mulch which recently replaced sand at the Civic Park playground in downtown Walnut Creek. According to the City of Walnut Creek web page, the sand was replace with mulch to comply with the Americans with Disabilities Act (ADA) and other Walnut Creek playgrounds will be replaced as well:
To comply with the Americans with Disabilities Act (ADA), sand is being replaced with mulch at several City park playgrounds. The playgrounds will be closed during the replacement project for about 3 days each. Civic Park playground will be closed beginning May 6, followed by the playgrounds at Tice Valley park on May 10 and Rudgear park beginning May 10 or 13. Signs will be posted several days in advance of the work.
The area where there is a water component still has sand though. My kid loved playing in the sand so this was disappointing to him although I appreciate not getting sand stuck in my shoes. I think it would still be difficult to maneuver in a wheelchair though.