Q.Building a sensory garden
Who can I contact that has expertise in building sensory gardens? Our park would like to add a sensory garden to our park.
Than you,
Tom Kavanagh

Check with local landscaping companies or garden centers.
Many garden nursery's would be happy to help you with projects such as this!
Here are some articles that will help you get started.
https://www.gardeningknowhow.com/special/accessible/sensory-garden-ideas.htm
https://www.gardeningknowhow.com/special/children/scratch-sniff-garden.htm
https://www.gardeningknowhow.com/special/accessible/visually-impaired-gardens.htm
https://www.gardeningknowhow.com/special/accessible/special-needs-gardening.htm