mr. prusing. there's been a lot of discussion in the media on conflicting timing about how long it took to shutdown the oil flow in the pipeline. can you describe that process in some detail. and in particular why couldn't you simply close the blocked valves on either side of the yellowstone river first? >> thank you very much for your question senator. first, let me run through what occurred on the evening of july 1. this particular pipeline is operated out of our operations control center in houston, texas. that is where we operate all of our pipelines across the united states. that is the typical technology for pipeline companies to have trained experts and all of the equipment running just single control center where you can operate the pipelines, the pumps, the valves from that one spot. at 10:40 p.m. mountain time on july 1, we saw a pressure drop on the pipeline in our control centers. the operators at that time did not know what was tallly occurring. they did not know a pump had shutdown,