This is an administrative order (AO) for compliance pursuant to the Clean Water Act issued to BioMarin Pharmaceutical, Inc. in Novato, California. The violation involves the national pretreatment standards in 40 CFR 403.5(b)(2) which prohibit the introduction of pollutants into a publicly owned treatment works (POTW) that will cause corrosive structural damage to the POTW, and in no case will discharges with a pH below 5.0 be allowed. The Order directs BioMarin Pharmaceutical to design, install, and startup a proposed system to achieve consistent compliance with federal and local pH limits and to self-monitor for one year to demonstrate consistent compliance.