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Margaret Place Pump Station Overview
Purpose
The Margaret Place Pump Station functions along with the adjacent detention ponds to convey stormwater and combined sewer overflow collected within the Margaret Place Drainage Basin through the flood protection levee .
Theory of Operation
The Margaret Place Pump Station was upgraded to provide stormwater and combined sewer pumping capacity to allow for continued future separation of the storm and sanitary sewers within the Margaret Basin. The reconstructed four bay pumping station includes the original three propeller pumps capable of pumping 16.8 MGD (26 cfs) each, and an additional propeller pump capable of pumping 33.6 MGD (52 cfs), upgrading the total pumping capacity of the Margaret Place Pump Station to 84.0 MGD (130 cfs). More information on the design of the Margaret Place Pump Station is presented in the Margaret Place Concept Design Memorandum .
 
Equipment
The Margaret Place Pump Station includes the following equipment:
  • Stormwater Influent (propeller) Pumps
  • Stormwater Influent Pump Reduced Voltage Solid State (RVSS) Starters
  • Wet Well Level Monitoring
  • Sampler Unit
  • Flow Monitoring  
  • Manual Bar Screen
  • Radio Transceiver
  • Emergency Engine Generator
Description

During wet weather events, stormwater and combined sewer overflow from the Margaret Place Drainage Basin is directed to the Margaret Place and 5th Street detention ponds. The Margaret Place Pump Station conveys this detention volume through the levee to the Mississippi River. The Margaret Place gate well is currently in the closed position at all times to provide the City with the ability to sample and record the volume of the combined sewer overflow, while the gate well at the 5th Street Detention Pond  (the higher pond) remains open during low river levels and is closed with the ability to divert flow to the Margaret Place Detention Pond during high river elevations.

Stormwater and combined sewer overflow from the detention pond(s) passes through a coarse manual bar screen and enters the pump station wet well (four separate pump bays). From the wet well, the water is elevated via four propeller pumps (one redundant) though individual discharge pipes to the existing Margaret Place gate well structure, creating a head differential and enabling water to flow through an existing 60" RCP sewer to the river. All flow is metered by insertion type magnetic flow meters on discharge piping for each pump.
Pumps are powered by RVSS starters and operate at a constant speed.

The pump station utilizes an Allen Bradley PLC to control the four stormwater pumps. The pump station communicates with the Clinton WWTP through radio transceivers, extending the existing Plant SCADA. There is a transmitter mounted upon the Margaret Place Pump Station, a repeater on a cell tower immediately adjacent the Chancy Fire Station, and a receiver at the Beaver Channel Pump Station.  

Alliant Energy provides the electrical service to the Margaret Place Pump Station. The pad mounted transformer and metering cabinet for the facility is located west of the Pump Station. Additionally, the location contains a new diesel powered emergency engine generator. An automatic transfer switch is hosted in the pump station electrical room, and switches operations over to the standby power in the event a power outage is detected.


As a remote, unmanned facility, the Margaret Place Pump Station is equipped with the following devices to provide alarm notification through SCADA back to the Clinton WWTP:
  1. The wet well (detention pond) high level and low level alarms are a part of the wet well level monitoring system. The system sends an alarm signal when wet well levels rise above or below a set point.

  2. Each pump bay is equipped with a low-low level switch. The switches send an alarm signal when wet well levels drop below a set point (wet well level 3.7 ft or elevation 576.0 ft).

  3. Room temperature transmitter located in the electrical room reads the room temperature and sends the data through SCADA to the operator.
  4. Intrusion alarm is installed on the electrical room door. This is a normally open proximity switch held closed by the door. Opening the door activates the alarm. A bypass key has been installed to allow City of Clinton staff to enter without activating the alarm.
  5. Status of the diesel engine generator is monitored by the system. The Operator is notified of a problem with the generator, including an alarm for low fuel.
  6. The automated sampler unit provides a common trouble alarm, indicating a problem with the sampler.     
  7. The UPS system for the PLC is equipped with an alarm that will signal the Operator of a problem with the UPS or loss of power to the UPS.
  8. The surge protection device in control panel 10-CP01 and switchboard 10-MSB01 is equipped with an alarm, signaling an electrical fault to the operator.

All data, as well as control and alarm signals are transmitted by radio to the Clinton WWTP. Data, control, and alarms can also be viewed locally at the Operator Interface Terminal (OIT) located in the main control panel (10-CP01) in the electrical room. Screens at the local OIT and Clinton WWTP are functionally identical.

Stormwater Influent Pumps 6
Four stormwater influent pumps are located in the Margaret Place Stormwater Pump Station and extend into the wet well. The four mixed flow propeller pumps lift stormwater flow up above critical Mississippi River levels and into the existing gate well structure, where it flows out to the river. All four pumps are operated at a constant speed and controlled by a reduced voltage solid state (RVSS) starter. The three original propeller pumps have a pumping capacity of 16.8 MGD (26 cfs), and the newly constructed pump has a capacity of 33.6 MGD (52 cfs), increasing total pumping capacity of the Margaret Place Pump Station to 84.0 MGD (130 cfs).

The pumps are designed to be operated during wet weather events when liquid level in the adjacent detention pond surpasses a set elevation. Pump control is in accordance with liquid level in the wet well as measured by a submersible type level sensor. Each pump is equipped with a drip-feed oil lubrication system. Oil level in the external pump reservoirs require manual monitoring.
Reduced Voltage Solid State (RVSS) Starters  6
The stormwater influent pumps are equipped with reduced voltage solid state starters which operate the pump motors at a constant speed. The soft start motor starters significantly reduce the in-rush current of the pump motor it is controlling, reducing energy consumption and unnecessary stress on the motors.     
Wet Well Level Monitoring 6
The liquid level in the wet well (detention pond) is measured by a submersible type level sensor. A high level and low level in the wet well sends an alarm to the HMI. Additionally, each pump bay is equipped with a float-tilt level switch, which provides a low-low wet well level alarm. A low-low detection in the wet well discontinues stormwater pumping via hardwired interlock.
Sampler Unit  6
Stormwater and combined sewer overflow to the Mississippi River is sampled by an ISCO Teledyne sampler, which is set to automatically sample flow every 30 minutes while the Margaret Place Pump Station is in operation. Samples are stored within the refrigerated unit.
Flow Monitoring 6
Flow from each of the four stormwater pumps is monitored by insertion type magnetic flow meters installed on the discharge pipes for each of the pumps and housed in handholes. Flow data is sent to the PLC which transmits the information to the HMI for display of instantaneous and totalized station flow.
Manual Bar Screen 6

A galvanized steel coarse bar screen is located in front of the new pumping bay. The screen has 3.0 inch openings to match the grating pattern of screens on the three existing pump bays. The purpose of the bar screen is to prevent oversized trash and debris from entering the wet well. The bar screen must be manually cleaned.

Radio Transceiver 6
The Margaret Place Pump Station is normally an unmanned facility. Communication with the pump station is established with radio transceiver equipment. The radio sends pump station operation status information back to the Clinton WWTP and receives control requirements from the remote HMI.
Emergency Diesel Generator  6
A diesel powered emergency engine generator is located to the west of the pump station. The generator serves the location, providing standby power to critical loads in the event of a temporary interruption of the main power supply provided by Alliant Energy. An automatic transfer switch is included in the MCC housed in the pump station electrical room and automatically switches operations over to standby power in the event a power outage is detected. The control systems are unchanged. It is recommended that the generators are exercised regularly. A permanent load bank has been provided and should be utilized for loading during routine maintenance testing.  
 

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Last Updated: 1/4/2019 5:24:25 PM
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