EE&T’s wastewater pumping experience has included the design or rehabilitation of grinder, submersible, and wet well/dry well type of pumping stations. Furthermore, EE&T staff are very familiar with the design standards for wastewater pumping including pump cycle times, pump capacity, pump efficiency, standby power, and instrumentation/control systems.

To compensate for the variation in pumping rates, our design work has incorporated the use of variable frequency drives and multiple level switches for efficient station operation. Our pumping station designs also incorporated other unique features such as permanent pig launching vault for future force main cleaning and supplemental wet wells for excessive wet weather flows. In addition to design of the pumping system and building, station designs have included ancillary equipment including pump controls and alarms, telemetry systems, emergency power, communitors, and screening equipment.

On our pumping station projects, the design has incorporated elements of flow projections to determine adequate wet well sizing and pump operating ranges. We consider this a critical element to minimize construction cost, both present and future. EE&T has engineered interim methods to reduce untreated discharge from a municipal pumping station in extreme wet weather conditions.

These methods include diversion of excess flow to other less stressed pumping stations, modification of pump control scheme to best utilize wet well capacity, and negotiation with a major industry to hold bulk sewer discharge during storm events and reduce the effect on the pumping station. Through EE&T’s efforts, this pumping station significantly reduced its overflow frequency from an average of 25 events per year to two events per year.

Temporary and Bypass Pumping - EE&T has utilized temporary and/or bypass pumping on numerous projects to facilitate construction. We have also utilized Godwin pumps for emergency raw water pumping facilities, to propel cleaning pigs and as alternatives to emergency generators.

EE&T has also utilized diesel driven pumps in lieu of emergency power generators in water and wastewater pumping stations. Our project for the City of Danville utilized a diesel drive pump (700 HP) to minimize the generator size.

Concrete Rehabilitation -EE&T personnel have been responsible for numerous concrete rehabilitation projects including wastewater wet wells, manholes and gravity sewers; water storage and treatment plant structures; and buildings. Many of these projects have been completed for structures more than 50 years old.

Infiltration/Inflow Analysis -Using continuous on-line monitoring equipment and Windows-based software, EE&T has conducted flow monitoring programs as a part of extensive sewer system infiltration/inflow (I/I) studies. I/I studies have also included the use of sewer cameras and smoke and dye testing to identify degraded infrastructure.

EE&T developed inspection and enforcement plans to address extraneous wet weather flow due to unauthorized service connections such as downspouts and sump pumps. From these studies, EE&T has developed short and long range rehabilitation programs utilizing trenchless technologies such as in-situ repair, slip-lining, grouting, as well as total line replacement methods.

For one project, EE&T examined the existing sanitary sewer collection system, using computerized flow monitoring, dye testing, smoke testing and field observations. Upon the completion of the examination of the sanitary sewer system a master plan was created recommending over 5,700 feet of sanitary improvements. EE&T completed plans and specifications for improvements to the total 5,700 feet of sewer line. Construction of the sanitary improvements included the use of sewer lining under creeks and through state right-of-ways where excavation for sewer replacement would be cost prohibitive.

Pumping Station Design -EE&T personnel have completed numerous pumping station designs including the use of vertical turbine and split case centrifugal pumps, with and without variable frequency drives. These projects included related appurtenances including piping, valves, controls, power, and integration with existing SCADA systems. EE&T personnel have often employed the use of skid-mounted pump systems and modular, prefabricated buildings to minimize construction and start-up time as well as costs. In addition to new facilities, EE&T personnel have been responsible for the modifications to existing structures, pump well cleaning and rehabilitation, chemical feed systems, and pump troubleshooting.

System Booster Pumping Stations — EE&T personnel have successfully completed the design of distribution system booster pumping stations ranging in size from <100,000 gpd to over 15 mgd. These projects have included new facilities and expansion of existing stations. Designs have been completed for the City of Newport News, VA, Erie County Water Authority, NY and the Niagara County Water District, NY. Designs have included modifications of existing pumps (by the manufacturers) to increase pumpage, addition of emergency power, control system improvements, electrical system upgrades, distribution system chemical feed addition and the installation of SCADA systems. Our experience in pumping station design clearly indicates that several key items must be considered for each project, including the following:

• Coordination with owner personnel, including engineering, operations, and maintenance.
• Hydraulics - It is essential that the facility design consider both current and reasonably anticipated future conditions.
• Pump selection - This selection must include compatible materials of construction as well as broad hydraulic capability. Prior experience of the owner with reliability, repairs, and response of local service representatives are critical issues in the selection and specifying.
• Controls - Integration with existing control systems, including SCADA, is critical to a successful project.
• Vibrations - The potential problems associated with vibrations is an area which is often overlooked during the design phase of a project, especially where existing facilities are being expanded and large vertical turbine pumps are utilized.
• Electrical - The expansion of existing facilities requires a thorough analysis of the entire electrical system, from the main service to the individual pieces of equipment.