WATER SYSTEM FAULTY PROGRAMMABLE LOGIC CONTROLER REPLACEMENT

Page 1 of 12 STATEMENT OF WORK PROJECT TITLE: NEC DWTP PLC REPLACEMENT. LOCATION: NEC UTILITY BLDG. 50 AV DES ETATS UNIS REFERENCE:2026 – NEC WATER TREATEMENT SYM – V.02 DATE:22-APR-2026 1. Project Statement Post Bujumbura has a need to replace a faulty domestic water treatment plant (DWTP) Programmable Logic Controller (PLC) and add BACnet to it to upgrade communication to Building Automation System (BAS) of which FAC team will be able to monitor real time levels, production and water distribution to the buildings. The current PLC Model Allen-Bradely MicroLogix 1200 has suffered from a fatal internal failure. 1.1 Work Description Post wants the service of a contractor who can. 1.1.1 Provide new unlocked Programmable Logic Controller (PLC) and HMIs for the controller. 1.1.2 Provide all hardware and software equipment (Laptop with carrying case, software loaded on PC, programming cable, and support connections to the installed Allen Bradley PLC.) 1.1.3 The PLC ultrasonic level sensor hardware shall be Ladder Diagram (LD), also known as Ladder Logic. 1.1.4 Provide and upgrade any input/output cards and new ethernet cables for the PLCs. 1.1.5 Provide all parts and materials associated with BAS interface with the new BACnet converter. 1.1.6 Provide the recommended software for the water tank production and level management system and include the labor required to install. 1.1.7 Provide a minimum of eight (8) hours of hands-on training for Facility personnel. Training shall cover software, system operations including system monitoring and alarm management, and basic troubleshooting procedures 1.2 Project Description: 1.2.1 For the PLC Work: 1.2.1.1 The contractor must replace and repair • the main cabinet PLC that has suffered from a fatal internal failure. • the RS232 port that is not functioning. This resulted in not being able to pull the current PLC program off for replacement. -- 1 of 12 -- Page 2 of 12 • Power to the input/output cards not functioning. • The built-in screen on the PLC is not functioning. The PLC goes immediately into a fault state upon power cycle, indicating an internal PLC error on the board/power distribution rail of the PLC. 1.2.1.2 Perform re-wiring in the main panel and label all the cables. 1.2.1.3 Contractors must ensure footprint of the new PLC, along with all of it’s I/O cards will fit into the existing cabinet or if there will be need to have an additional cabinet. 1.2.2 For the BAS Integration: 1.2.2.1 Main cabinet does not have enough room to mount the BAS module. The contractor will perform conduit work between one of the pump cabinets and the upgraded BAS module in order to utilize it. Cat 5/6 would need to be run from the pump panel to the BAS system, and 5 conductors ran from the main plc to the new BAS module. 1.2.2.2 The contractor must capture all points from the potable plant into the BAS system with the current design. 1.2.2.3 The contractor must capture all points from the pump panels (Booster and Triplex pumps) and relay to BAS system through upgraded BAS Module (BACnet). 1.2.2.4 The contractor will add an ethernet switch to make sure both points for Potable panel and pump panel are relayed to BACnet for BAS system. 1.2.2.5 Note that certain points are already hardwired from the RO plc’s to the main PLC, the contractor must confirm if the wiring is still usable and in good condition. 1.2.2.6 The PLC sourcing and sinking points are detailed in wiring diagram from page 12 to 30. 2.0 System Overview 2.1 System Description This system is designed as five skids including bag filters and chlorination skid, media and carbon filters skid, two RO skids and PH adjustment skid. The complete treatment system is designed to provide up to 9000 gallons per day of potable quality water. Using city water or well water as the feed source. See system P&I Diagram in figure 1.0. 2.2 Sequence of Operation Feed water is supplied to the RO unit at dynamic pressure. Feed water enters the system through an Inlet valve. Next, the feed water passes through a pre-filter for removal of suspended particles 5 microns or larger. The filtered water enters a high-pressure pump which increases the water pressure to RO operating levels. -- 2 of 12 -- Page 3 of 12 Inside the membrane assembly, a portion of the feed water, referred to as product, passes through a membrane barrier that rejects suspended and dissolved solids. The remaining portion of feed water, referred to as reject, carries concentrated contaminants out of the membrane assembly. The product water from the membrane assembly is monitored for conductivity. A Programmable Logic Controller (PLC) controls the RO functions to maintain most efficient operation within the design parameters of the system. Recovery, an important operating parameter, is the ratio of the product water to the feed water flow. Designed recovery rate for this system is 52%. See the System Specifications section 2.2 of this SOW for details. 2.2 System Specifications 6.25 GPM These specifications are based upon computer generated projections. The projections are determined by feed water chemistry, temperature, predicted capacity and anticipated 3-year flows. Supply to Reverse Osmosis Unit (1”)......................................................................... 12 GPM (45.4 LPM) RO Product to Service/Storage (3/4”) ...................................................................... 6.25 GPM (23.7 LPM) RO Reject to Drain (3/4”) ......................................................................................... 5.75 GPM (21.7 LPM) Daily Total Permeate Production ...............................................................................................9,000 GPD Expected Feedwater TDS ..........................................................................................................................1000 MG/L RO Product Water TDS .......................................................................................…