Carollo Engineers 1/8/2024 Amendment 1

COMBINED SEWER CONVEYANCE PROJECT – SCOPE OF WORK CATEGORY 2 – FOR OFFICIAL USE ONLY / DISCLOSURE PERMISSIBLE BY LAW 1 EXHIBIT A SCOPE OF WORK ENGINEERING SERVICES CITY OF EVERETT WATER POLLUTION CONTROL FACILITY COMBINED SEWER CONVEYANCE PROJECT INTRODUCTION The Combined Sewer Conveyance Project will bypass combined sewage (CS) flows that exceed the headworks and/or primary treatment capacity directly to the oxidation pond recirculation channel at the Water Pollution Control Facility (WPCF). This will reduce the washout of solids from Aeration Cells 1 and 2, which happens under the current configuration with CS flows passing through the aeration ponds and then into the oxidation pond recirculation channel. A study was performed in 2022 “Engineering Report, Everett WPCF Combined Sewage Conveyance Improvements, January 17, 2022, Stantec,” that identified changes needed to the CS bypass conveyance system to route flows directly to the oxidation pond recirculation channel downstream of diversion structure 1 (DS 1). A follow up study evaluated an alternative for routing the CS bypass pipes to avoid crossing wetlands and considered options to incorporate improvements planned to diversion structure 0 (DS 0) as documented in the “Basis of Design Report Diversion Structure 0 Improvements, April 29, 2016, HDR.” The follow up study is documented in the “Alternatives Comparison Report, Draft April 2023, Carollo Engineers, Inc.” The selected alternative is to redirect CS flows immediately after DS 1 to the oxidation pond recirculation channel. The proposed project constructs a diversion structure onto line C and a diversion structure downstream of DS 1 to intercept bypassed CS flows and route them through two buried pipes constructed using open-cut methods through the adjacent wetland for discharge into the oxidation pond recirculation channel. Under this scope of work, the Consultant will advance the alternative selected in the 2023 Alternatives Comparison Report by preparing an engineering/basis of design report, completing design of the improvements, preparing applications for environmental and building permits, and preparing documents for construction of the project by a contractor selected through competitive bidding. The Scope of Work performed by the Consultant includes the following tasks:  Task 100 - Project Management  Task 200 - Geotechnical Engineering Services  Task 300 - Environmental Permitting Services  Task 400 - Engineering/Basis of Design Report  Task 500 - Design and Preparation of Documents for Construction  Task 600 - Bid Period Services