Sigra manufactures and uses its own stress change cells for use in rock or concrete. These are strain gauged tubular devices are which are incorporated into a cementing pipe. Cement grout is pumped through the cementing pipe and the transducer. The cementitious grout expands and locks the transducer in place within the borehole by post initial set expansion. This actively loads the transducer via the grout to the borehole wall. Thus both stress increase and decrease may be measured. The grout filling of the borehole makes the installation robust and avoids problems changing the drainage situation by leaving an open borehole.