Back in 2012, the MBTA funded a project to improve the drainage. The project was executed sometime in early 2013 - I can't find a reference to exactly when, but it resulted in the two new sheds that you can see on the west end of track 1. Here are two articles:
MBTA to improve drainage at Natick station (8/20/2012)
T preparing to start station drainage improvements in Natick (12/29/2012)
The problem is that the Natick Center is depressed 'beneath' downtown Natick. The only drainage from the station is to the northwest towards Lake Cochituate. And there isn't much of a slope (at least initially) away from the station.
On Friday morning, 8/21/2015, sometime between 7 AM and 7:29 AM, Natick got slammed with a huge downpour. Dave Epstein in South Natick reported 1.51 inches of rain in the storm. I'm saying after 7 AM, since P582 made it through without any trouble (apparently), and P582 should be passing through on track 2 about 7 AM.
When P506 arrived close to it's scheduled arrival time of 7:29 AM on track 2, the track was flooded. Here are two pictures just before P506 arrived (click on the Read More):
I think this is a video of P506 arriving at Natick Center:
Here is a picture of P506 at Natick Center:
After that, P506 reversed out of Natick Center and went back west to West Natick. Here is a video from the reverse move. Note the shed with yellow posts ("bollards") next to it. That's the pump equipment installed in 2013.
The normal AM schedule has outbound P507 passing through West Natick at about 7:48 AM on track 1 (it doesn't stop there usually). It normally terminates in Framingham and 'turns' to become inbound P510.
Keolis made a great decision (on the fly) to stop P507 at West Natick and have the passengers of P506 transfer from the original P506 equipment on track 2 to the P507 equipment on track 1. This train became P506 and proceeded eastbound on track 1. This was a great solution because it actually minimized the delay to everyone - P506 passengers and P508 passengers, who all would have been even more delayed if those trains would have ended up all the way back in Framingham.
Also important to note is that the only relevant switches available to move trains from track to track are in Framingham and Weston. It has long been noted (officially and unofficially) that the Framingham / Worcester line has way too few switches - and more switches certainly could have helped this morning.
Here are pictures of the passenger transfer operation at West Natick:
Since P507 equipment was being used as P506, there was no equipment for P510. Keolis made the decision to have P508 make all local stops inbound - essentially to pick up the P510 schedule. Not sure how necessary this was, since the 'new' P506 could have grabbed all the passengers waiting for P510, but it doesn't matter - P508 was now too close to P506 to operate as an 'express' - it would have been stuck behind P506 following close behind whether or not it would have made the local stops.
Both P508 and P512 (a train that originates in Worcester) went inbound on track 1 around the flooding in Natick. The original P506 equipment went back out to Framingham. It then went inbound as a somewhat delayed P514, since the usual P514 equipment is P509, an outbound train that terminates in Framingham. P509 got stuck at the Weston switch waiting for all the trains to clear. It eventually made it to Framingham and then went back in as a 'light' non-revenue move (no passengers) just to get the equipment back to Boston.
Here is a video of P514 (the original P506 equipment) arriving at Natick:
The situation was pretty much cleared and back to normal by the time P516 came through Natick, on it's normally scheduled track 2, close to it's scheduled time (9:31 AM). It was given permission to proceed through Natick at it's normal speed.
What a morning!
It is important to note that this situation was NOT due to a failure of the new pumping station. Pumping stormwater is never a great engineering solution - there will always be a storm that will be more than the pumps can handle. Engineers always try to find a stormwater solution that only uses gravity (and BIG pipes). But that's not possible here in Natick Center - the topography (that dates back 100 years) is the problem. So this event was just bad luck - a storm way too big for the 'new' pumps to handle, and extra bad timing with the storm at the height of rush hour. The situation was probably made worse by the saturated area due to the recent storms. Without the 'new' pump station, it is possible that BOTH tracks would have flooded and NO trains would have been able to get by on EITHER track. 'Bustitution' (substituting buses for trains) might have been the only solution, and that would have been a nightmare.
See this exchange:
Here are more pictures and videos (the first is of P516), including another live report from Michael Henrich (he's becoming too frequent of a visitor to our train line!)
Crazy thing is, this exact same thing happened on Sunday August 15. See these pictures and videos: