Dont mean to disagree with what your saying as i know its is very difficult to get the council to do anything like this, But it is posible a group of us got together in my village and got them to build use a half pipe (Y)
I think they got round the health and safety issue buy putting up signs to say anyone under the age of 16 must be accompained by an adult and anyone else useing the place does so at there own risk.
We went to the village parish council with our idea, We thought they would have more time to think (sort it out) than the main council. and they did sort it quite quickly
Good Luck to you mate (Y)
P.s Tell them this will help keep you all off the streets etc this may help