Residents parking on grass area

A number of residents are continuing to park on the grass area causing damage to the land making it very unsafe to walk over. Someone could easily trip over. It is the same cars/vans parking on there over and over again. There is space to park elsewhere on the street but they just dump their car on the grass. Please put some bollards/cones or hedges along the edge of the curb to stop this from happening. One of the residents has pulled the bollards out of the ground so they can park their cars on the grass. The bollards have been dumped by the salt bin, could this be considered fly tipping? Residents are damaging council land as well as removing bollards that the council put in to stop some of the parking on the grass.