A large supply dump was established at Watten next to the River Aa. This site was eventually used to store material required for all the V-weapon sites in the Saint-Omer area. Building materials were brought there by barges and trains where they were unloaded onto a Decauville narrow-gauge railway for transportation to the construction site, where concrete mixers operated day and night. A 90 kV power line running to a transformer at Holque north of Watten provided electricity. An old quarry at Wizernes codenamed "" (Gravel Quarry Northwest), some south of Watten, was also converted into a storage dump to supply the Watten facility.