Abstract: A method of filling an annular space between inner and outer coaxially arranged pipes while providing the option of maintaining fluid flow through the inner pipe includes optionally establishing fluid flow through the inner pipe; installing first and second seals in the annular space between the two spaced apart pipes at first and second ends of the pipes and inserting one end of a vacuum tube into the annular space through the first seal at the high point in the first seal. A grout tube is inserted into the annular space through the second seal at the high point of the second seal. A vacuum is applied to the second end of the vacuum tube and a grout mixture is applied to an opposite end of the grout tube. A sufficient vacuum is maintained within the annular space for such a time period to draw the grout mixture from the second end to the first end of the pipes to completely fill the annular space.