One witness described how BP mixed a large quantity of two chemicals and injected them into the well to flush out drilling mud. But the chemicals aren't usually mixed together, and the injection of more than 400 barrels of dense, gray fluid were about double the quantity normally used for the task, said Leo Lindner, a drilling fluid specialist for contractor M-I Swaco.

The reason for the action: BP had hundreds of barrels of the two chemicals on hand and needed to dispose of it, Lindner testified. By first flushing it into the well, the company could take advantage of an exemption in an environmental law that otherwise would have prohibited the discharge of the hazardous waste into the gulf, he said.

"It's not something we've ever done before," he said.

From:
http://www.washingtonpost.com/wp-dyn/content/article/20...

Test on both relief wells both blow out preventers failed test

"problems found:
        * During ROV hot stab testing, the Lower Marine Riser Package disconnect function was unsuccessful because of a leaking shuttle valve.
        * A failed shuttle valve caused an unsuccessful test of the All Stabs Retract function.
        * A failure of the deadman test because a shuttle valve was installed that should not have been.
        * A broken solenoid connection on the blue pod that prevented that pod from closing the casing shear rams."

http://tpmmuckraker.talkingpointsmemo.com/2010/07/bps_r...