Mcmillan Backwash Discharge to Sewer

The Washington Aqueduct provides potable water to approximately one million people in the District of Columbia and Northern Virginia. As part of the water treatment and supply system, the Washington Aqueduct maintains and operates the Dalecarlia and McMillan Water Treatment Plants (WTPs). At the McMillan Plant, water from the filter backwash process is currently disposed of in a cove area of the McMillan Reservoir and it is separated from the reservoir by a silt curtain. This project involves the construction of two 330,000 gallon equalization basins as well as a pumping station that removes all water and residuals from the basins. Also included are flow channels to the equalization basins and flow pipes to the DC Water's combined sewer system along with gates, valves, flow metering and SCADA controls. Work must be performed without any disruption to plant operation or damage to existing infrastructure. The work involves the excavation and construction of concrete basins, installation and testing of required equipment to collect and control filter backwash water and the piping system to discharge it directly to DC combined sewer system or to direct it into the equalization basin. Part of the work must be performed within time-constrained limited outage windows. Specific work items include supply and installation of large pipes including valves and fittings, a chemical addition unit, two equalization basins, submersible pumps, electrical switchgear and associated equipment, pipes, flow meter and flow control valves etc. Hence, an experienced contractor with resources and expertise to handle the following project constraints is needed and must be capable of: I. General excavation and hauling at an industrial facility such as a water treatment plant without disrupting plant operations. II. Excavation and shoring in limited spaces removing buried and abandoned infrastructure and adjacent to active buildings and structures. III. Installation of pipes, valves, flow meters, construction of equalization basins as well as installation of submersible pumps and associated equipment. IV. Connections to active mains, sewer systems and water filtration channels under limited time constraints. V. SCADA automation programming in accordance with Federal information technology security provisions. 1. The construction of portable water storage basins and/or pumping stations. 2. The installation and commissioning of electrical equipment to include a switchgear, transformers, variable frequency drives, distribution panels and conductors. 3. The installation of submersible flap gates, pumps and motors. 4. Modifications and programming of control systems for pumps, flow meters and process system instrumentation. 5. Scheduling and managing multiple work crews to manage various construction activities and installation of equipment simultaneously within tight timelines. 6. Performing work in confined spaces with trained and certified personnel in a timely manner. 7. Experience with USACE contract administration procedures to include the use of QCS, submittal processing, etc.

Division 03 -	Concrete, Precast Concrete.
Division 33 -	Utilities, Storm Drainage Utilities, Storm Utility Drainage Piping, Storm Utility Water Drains, Storm Drainage Structures.