Currently apache runs on prefork mpm. This is not awesome but we aren't using php-fpm and now varnish is out of the picture since we don't have SSL termination in the mix either.
Here are the current apache settings. They may need to be tweaked if the next TW bombs the box.
<IfModule prefork.c> StartServers 6 MinSpareServers 4 MaxSpareServers 10 ServerLimit 40 MaxClients 40 MaxRequestsPerChild 4000 </IfModule>