The Salberga prison in Sala is a Class 1 correction facility with a capacity for 248 inmates, which makes it one of Sweden's largest correction facilities. A Class 1 facility is the highest security level facility in Sweden with isolation cells. There are approximately 300 employees at the institution, most of them prison wardens.
Prisoners in isolation are inventive so to be able to communicate between the cells they began to use the sewer system as a communication channel. By siphoning the water from the toilet, they were able to talk to each other through the sewer pipes. When this was discovered by the Wardens measures had to be taken.
Salberga Correction Facility contacted Wapro to enquire about the acoustic qualities of WaStop. Acoustic tests were done on WaStop with good results, which led to a number of WaStop installations as a sound barrier to prevent the inmates from communicating through the sewer pipes, but still allowing sewer to flow through as required.
A very different use of the WaStop!
