Getting moisture out of a wall?

After a pretty good rainy season and incorrect sloping of outer flooring the wall one corner of my listening space seems pretty impregnated with water. I'd removed paint and bubbly plasterwork, left the wall bare for a few days then reapplied rhinolite. Two weeks later there are still parts of the wall that remain wet - the rhinolite is visibly darker and cold to the touch - much colder than surrounding areas where the rhino lite has gone white as it does when dry.  On the outside of this wall is the spot that's has the most water exposure - a down pipe leaving water against the wall as well as water runoff from around the corner collecting in the same spot.

Measuring the moisture in the concrete floor in that corner of my listening space yielded 17% - 7% is the highest the flooring contractor will accept before installing a wooden floor.  Any ideas how to get the moisture out of the wall?