Investigators have communicated with the suspect through a length of PVC pipe that extends out of the bunker.

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And in between the brick walls, Davis remembers something else: A PVC pipe that ran from the bunker to the front of Dykes' property.

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You can take PVC pipe, and you can either use soil or you can use it hydroponically, but you just cut the ends of it.

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The suspect, who police have identified as Dykes, is holed up in a bunker 4 feet underground and built at least partially out of PVC pipe, authorities have said.

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Late in the evening, the man had the child in some sort of underground bunker or storm shelter, and SWAT team members were communicating with him through a PVC pipe, CNN affiliate WSFA reported.

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Al-Tunisi's group is also planning the water, power, logistics and safety backups for an industrial park adjacent to the plant, where manufacturers will be lured in to transform raw plastics into the likes of PVC pipe, injection-molded automotive parts, packaging and carpets.

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At Gadget Camp, sponsored in part by a foundation affiliated with the Fabricators and Manufacturers Association, girls learned how to make a lamp, a candy dispenser, and other useful items out of various materials including wood, metal, fiberglass and PVC pipe.

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This somewhat dangerous device had a six foot barrel, was made out of PVC irrigation pipe of varying diameters, and was powered by compressed air.

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