2600 FEDERAL AVE 2021 PORT OF EVERETT 2025-09-29

Iq:I Consulting Engineers Page 11 of 13 Contech Stormfilter systems have received General Use Level Designation (GULD) from Ecology for 'Basic' Water Quality treatment and Conditional Use Level Designation (CULD) for enhanced heavy metal treatment requirements. A level of 'Basic' treatment is anticipated for the south gate area of the Norton Terminal which will generally see truck traffic through the gate. 5.5 Chitosan Enhanced Sand Filtration System Analysis(Basin M) The Chitosan Enhanced Sand Filtration system will be installed in Basin M and shall be sized for the water quality flow rate of 3.55 cfs(1,593 gpm) as determined by the WWHM2012 modeling software. The capacity of the CESF system based on equipment sizes will have a treatment capacity of 3.56 cfs (1,600 gpm). The final design of the CESF system may vary depending on vendor and influent stormwater characteristics, but generally will consist of the following steps: collection, water quality monitoring (for pH, turbidity, and conductivity), and dosing stormwater with a chitosan acetate solution for stormwater solids settling in tanks before sand filtration and discharge of treated stormwater. The chitosan acetate is a biopolymer that is dosed into the water to coagulate fine particulate and suspended solids, generating floc for settlement in the tanks prior to filtration.The CESF system also monitors influent and treated stormwater for water quality parameters, pH, turbidity, and conductivity. Treatment loops are incorporated to recirculate for additional treatment if water after treatment doesn't meet turbidity requirements for discharge. The CESF system can be modified (or added to) to treat future pollutants. Dosing rates, chemical selection, and additional storage tanks, or filter pods, as well as add on systems can be incorporated to help meet modifications to existing benchmarks/levels or future pollutant removal requirements. Refer to Appendix C for typical CESF equipment components. The CESF system has received General Use Level Designation (GULD) in Ecology's — TAPE program. This classification demonstrates that CESF systems can effectively meet pollutant reduction goals associated with basic and enhanced treatment requirements. Similar CESF systems have been installed at other Puget Sound Port terminals over the past 5 years. 5.6 High-Flow Bypass Structure Calculations(Basin M) A high-flow bypass structure will be installed on the new 36 inch storm line for Basin M.This structure will also have an integrated pump station (see section 5.7 below for more information).This structure will divert the water quality flow rate to the pump station side of the structure via weir and orifice control.The orifice has been sized so that no more than 10%of the flow will be sent to the lift station for treatment at the 100-year storm event. When the stormwater inflow rate exceeds the water quality design outflow rate,the water surface in the high-flow bypass chamber will rise to elevation 10.43 where it will begin to pass over a weir wall and will discharge to Port Gardner Bay via Outfall M. See Appendix F for the high-flow bypass structure weir and orifice calculations.