outhouse utility room conversion

[Bill]

im converting an out house into a utility room. their is already a drain for sewage as theres a working toilet in there. we want a washer in there. plumbing in the washer is easy really. going too draw off the water form the toilet supply pipe as theres good pressure and flow so the tricky bit is how do i convert the old cast iron soil pipe from the wc so i can drain off from the washer into it? someone did suggest that i can just drain the washer water outside on to gravel but i figured this sounds somewhat dodgy as the waste water would be full of chemical from soaps and detergents. any advise would be good cheers. also i do think this outhouse used to be a utility room or someone has tried as along with light theres recently tested electrics in there eg sockets and trips etc.

 

[Reg Man]

Cast iron soil pipe boss

 

[woodytheplumber]

I don't personally like connecting to cast so I would replace all of part of the stack with plastic and use a boss or a stap on boss onto plastic