For several years, NASSCO has worked with independent research groups to better understand potential health concerns regarding styrene used in the cured-in-place pipe lining process. The first three phases of research focused on emissions from the cure process, while the primary objective of the Phase 4 study was to quantify the effects of residual styrene in cure water discharges from CIPP installations on secondary biological treatment processes typical of publicly owned treatment works in the continental U.S. The focus was on potential inhibition of biochemical oxygen demand removal and ammonia-nitrogen removal (nitrification).The Phase 4 study included the following elements:Literature reviewA
