Plants for septic tank percolation zones?

What can I safely plant over a septic tank percolation zone (approx 40×25 metres) without interfering with its function? The area is unshaded, exposed to all winds and naturally low lying, always damp and sometimes boggy. There is no opportunity for additional drainage, nor resiting the tank or soakaway. Thankfully the installation works well inspite of its situation!The “garden” of my new-build home is still an exposed, one acre field on the Ards peninsula, one and a half miles from the Irish Sea to the east and Strangford Lough to the west.