Shore Guy,
Much in the way of estimates is available ... not very much in the way of hard data (as in experimentally verified numbers)
In this neck of the woods, the rules HAVE, for as long as I can remember, required the operator to apply a suitable correction for runway degradation .. they have, however, never got down to the nitty gritty of how that sort of thing ought to be done .... so some of the operators ... sort of ..... hope that the problem either won't bite them or will somehow go away ...
Perversely ... the ASDR becomes less of a problem as the contamination increases due to increased drag associated with the aircraft's having to play motorboats ... as you would understand, being a boatie .... the continued takeoff consideration is, on the other hand, a major worry.
Nothing at all inconsequential about either the calculations or the physical significance of the problem ...
Mutt has more detail on this stuff than I do ... perhaps he might put his cap and gown on and produce a comment or three for the interest of all ?