CONCRETE PIPE How it Works (continued) Surface access for ease of maintenance Weir directs water to quiet chamber below Durable precast concrete Patented technology prevents captured pollutants from scouring Impervious liner provides double wall containment for hydrocarbons Treated water exits unit Captures and stores a wide range of particle sizes, from 20 to 2,000 microns, for later removal Free oils are trapped for later removal Sediment lies dormant for later removal Quiet chamber creates ideal conditions for free oils to rise and sediment to settle PAGE 4 LAFARGE PIPE eMANUAL