You get into a number of problems here:
1. There are four separate turtle deposition layers here, not one. Where did the extra turtles come from in the midst of a global flood when practically everything is dying everywhere, and why do they settle down in four separate layers instead of one - over pretty much the exact same unit?
2. In relation to this, how did you get four separate limestones and turtles right above limestones? Assuming that only hydrological separation is used, there should be no reason to get very widely spaced layers of limestone between large layers of mudstone, and turtles only in mass mortality assemblages above limestones. You have two choices: the turtles died as the limestone was being deposited, or right after the limestone had been fully deposited. If they died as the limestone was being deposited, they should disrupt the limestone sediment. If they died right after the limestone had been fully deposited, you essentially still need to cram four limestone deposition events (and four corresponding mudstone deposition events) into roughly a year, or 40 days per layer (amounting to half a meter a day), and you need to get turtles in precisely as the limestone has been finished, before the mudstone has started, without making it look like they disturbed either of the sedimentation processes. (And I'm being kind. There are only four turtle mass death layers, but there are actually more than four limestone layers in there.)
3. And, how do you get volcanic ash into the sediments right between the limestones and the mudstones? Mudstones are very fine sediments (measured in hundredths of mms), whereas volcanic ash is anything under 2mm. If you rely on hydrological sorting, there should be no reason for the ash to sort out so neatly. Furthermore, if the flood covered the whole earth from the 40th day onwards, out of a year, then for the majority of the time volcanoes were underwater, and underwater you wouldn't expect ash particles to go very far at all. Your own rapid sedimentation theories mean that ash ejecta from submarine volcanic explosions (if indeed they produce any ash at all) should be rapidly deposited, especially since ash particles on average have much larger sizes and should thus be deposited far more easily than mudstones.