Hi Davis. If I may ask a ...

Hi Davis. If I may ask a question, are you seeking to prevent contamination during constructuon of the structure, post construction, or both? Also, I am assuming your using concrete for the construction of the structure. Have you consulted with your supplier to get suggestions from them? We have several ways to arrest leakage by using certain admixtures and cementitious constituents in the mix. Most suppliers work well to come up with ways to meet the project's performance needs. Feel free to contact me if they are not responsive.