moutain stream/liner

hi guys,

i'm currently building a mountain stream in my garden (project that has
been ongoing since last summer!) and have finally got to the stage where
i've shaped the stream from cement and has set very nicely.

i have a large piece of butel(sp?) liner that i intend to cut down and
line the stream with. the only trouble is i need to hold the liner in
place, unfortunately rocks won't do the job. i wondered if i could use
some cement to hold the liner in place... or will the lime/chemicals in
the cement in time eat away at the liner?

can anyone suggest something suitable to use if cement is no good? the
stream is about 3 metres in length.

thanks


--
cambo