With Lundus dead, Hank and Britt had to scramble this week to cover their tracks, especially after Mark made it clear that he may get booted from the case if he can't find Lindus and won't be able to help Hank and Britt in the future.
It didn't help matters to have Lindus' wife accusing Hank and Britt, correctly of course, of kidnapping her husband.
The partner decide to run Lindus and his car off the road and make his death look like an accident. With this done, the two appear to be in the clear...
... but then Steph mentions something to Hank: the papers that Lindus had in his possession (which Gretchen and Jason both confirmed proved that the construction company was covering up pH levels in the ground, and which got leaked when Lindus' body was found with them on his person) were actually forged. It's physically impossible for the chemicals on there to be mixed together in such a way.
Upon hearing this, Hank stopped back at the construction site and wondered why the company would fake these documents. It must be to bring stuff in to the area somehow. But what?!?