Hi Vertrad,
Does the text mention the type of gates (
затворы) stored in this facility?
Internet sources suggest that
затворохранилище is mostly used for the storage of
ремонтные затворы (
bulkhead gates), e.g.: "... определенное число ремонтных затворов сохраняют обычно в специальных затворохранилищах и доставляют их к месту установки при помощи кранов" (
http://hva.rshu.ru/ob/gidroteh/uch/1/chapter8/1_8_1.htm). If it follows from the context that these are
ремонтные затворы, I would suggest rendering it as
bulkhead (gate) storage facility or
yard.
According to Multilingual Technical Dictionary or Irrigation and Drainage (1978),
ремонтный затвор is
bulkhead gate.
If the type of the gates stored is unclear, I think it would be safe to use a more general term for
затворохранилище, i.e.
gate-storage yard/facility