fky ash concrete for potable water containmen

huangyhg

fky ash concrete for potable water containment
are there any concerns with the use of fly ash in concrete for a tank that will be storing potable water?  we have a project that is trying to be as "green" as possible and would like to use a high fly ash content in the concrete.  knowing that fly ash -even that rated as non-hazardous- can contain high levels of heavy metals, i wonder if there is a possibility of heavy metals leaching into the water over time?
we are doing a renovation to a large storage tank, about 60 years old, that is likely to be in service at least another 60 years and i don't want to take chances.
thanks!
susan
have you considered ground granulated blastfurnace slag (ggbs).  it's currently a better product in the uk and can replace more of the ordinary cement in the mix.  both pfa (fly ash) and ggbs are accepted by the british code bs8007.
flyash has been a standard component of concrete for potable water reservoirs here for decades.
any heavy metals, which are pretty miniscule, are locked in the cement matrix and can't leach out.  
generally coatings for potable water are certified by nsf in the us.  i don't know if they've ever gotten into certifying concrete or not.