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1st Avenue Pump Station Overview

Purpose
The 1st Avenue Pump Station pumps wastewater flows from Basin 6 (including discharge from the 20th and 25th Avenue Pump Stations) to the Beaver Channel Interceptor, in route to the Clinton wastewater treatment facility. Additionally, new CSO pumps provide pumping capacity during peak wet weather events.
Theory of Operation
The 1st Avenue Pump Station replaces the aged existing sanitary (combined) pump station. It includes a new sanitary pumping station with a firm design capacity of 25 mgd, matching the capacity of the existing Beaver Channel Interceptor. Additionally, the pump station includes new combined sewer overflow (CSO) pumps with a total capacity of 33 mgd provided by two pumps, matching the existing CSO pumping capacity of the original station. The sanitary and CSO wet wells are separated by a concrete wall. More information on the design of the 1st Avenue Pump Station is presented in the 1st Avenue Pump Station and Force Main Concept Design Memorandum.
Equipment
The 1st Avenue Pump Station includes the following equipment:
  • Sanitary Sewer Pumps
  • Sanitary Sewer Pumps Variable Frequency Drives (VFDs)  
  • CSO Pumps 
  • CSO Pump Reduced Voltage Solid State (RVSS) Starters
  • CSO Sump Pump
  • Sanitary Wet Well Level Monitoring
  • CSO Wet Well Level Monitoring
  • Sanitary Flow Monitoring
  • CSO Flow Monitoring  
  • Sanitary Channel Grinders
  • CSO Influent Manual Bar Screens
  • Slide Gates
  • Radio Transceiver
  • Emergency Engine Generator
Description
The cast-in-place structure of the 1st Avenue Pump Station consists of an influent channel, valve vault, and divided wet well. This is an underground unit that is controlled and powered from the Pump Station PLC and electrical gear in the Electrical Room located above the wet well . The Pump Station receives flows from Basin 6 and the upstream pumping stations located at 20th and 25th Avenue. Flows from the 1st Avenue Pump Station are propelled via pumping to the Beaver Channel Interceptor, in route to the Clinton wastewater treatment facility. 

A new concrete diversion structure constructed on the existing 8-foot x 12-foot reinforced concrete box directs wastewater flows to a  66-inch FRP influent pipe . These flows  along with a 24-inch PVC gravity line conveying flows from the nearby levee toe-drain system enter the Pump Station's influent channel. From the influent channel, flows are directed through a low flow channel grinder (GRD-01) to manage influent wastewater particle size, before entering the sanitary wet well. In the event that the water level in the influent channel increases above a set elevation indicating that the incoming flow is exceeding the capacity of GRD-01, influent flow will overtop a weir wall and be directed to the sanitary wet well through a second, larger channel grinder (GRD-02). From the sanitary wet well, four submersible non-clog centrifugal pumps (two small and two large), driven by VFDs, propel wastewater up to the valve vault. Discharge piping for each pump contains an air/vacuum release valve, as well as lever swing check and isolation plug valve. Each individual discharge pipe connects to a 30-inch combined header, which exits the valve vault and transitions to a 30-inch PVC force main. All flow is metered by a magnetic flow meter in a metering manhole located onsite. Bypass capabilities for isolation of the meter are incorporated. 

Additionally, the pump station includes two submersible non-clog centrifugal CSO pumps. The CSO pumps provide capacity for peak wet weather flows. A concrete wall separates the sanitary wet well from the CSO wet well. In the event that the capacity of the sanitary pumps is insufficient for the flow demand (e.g. during certain wet weather events), the influent channel level will rise and influent flows will overtop the CSO weir wall, entering the CSO wet well. To control solids and floatables, all flow entering the CSO wet well will pass through a manual bar screen. From the CSO wet well, the CSO pumps propel combined flow up to the valve vault. Discharge piping for each pump contains an air/vacuum release valve, as well as lever swing check and isolation plug valves. The individual pump discharges connect to a combined header and exit the valve vault, passing through a metering manhole. Metered flow is then directed to the Mississippi River via existing 36-inch steel pipeline from the abandoned pump station and gate well structure on the wet side of the levee. 


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

Alliant Energy provides electrical service to the 1st Avenue Pump Station. The pad mounted transformer and metering cabinet in the northwest corner of the site. Additionally, the location contains a diesel powered emergency engine generator and load bank for routine testing. An automatic transfer switch is hosted in the pump station electrical room, and switches operations over to standby power in the event a power outage is detected.

As a remote, unmanned facility, the 1st Avenue Sanitary Pump Station is equipped with the following devices to provide alarm notification through SCADA back to the Clinton WWTP:
  1. The wet well high-high and low-low switches are a part of the wet well level monitoring systems. The switches send an alarm signal when wet well levels in either the sanitary wet well or CSO wet well rise above or below a set point.
  2. Status of major equipment (pumps, grinder, generator etc.) is monitored by the system. The Operator is notified of a problem with the equipment.
  3. The Valve vault level element is a conductivity type level switch alerting operator of a major leak in the valve vault.
  4. Each metering manhole includes a level element (float switch), which sends an alarm signal indicating a major leak in the respective metering manhole.
  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. Intrusion alarm is installed on the electrical room door. This is a normally open proximity switches held closed by the door. Opening the door activates the alarm. A bypass key has been installed to prevent entrance by City of Clinton Staff from activating the alarm. 
  7. Room temperature transmitter located in the Electrical Room reads the room temperature and sends the data through SCADA to the operator. Alarms are set at 45oF and 90oF.
  8. 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.
  9. The surge protection devices in control panel 01-CP01 and panels 01-MSB01 and 01MCC01 are equipped with an alarm, signaling an electrical fault to the operator.

All alarm signals are transmitted by radio to the Clinton WWTP. Alarms can also be viewed locally at the Operator Interface Terminal located in the PLC panel (01-CP01) in the Pump Station Electrical Room. 

Sanitary Sewer Pumps6
Four sanitary sewer pumps, two small and two larger, are located in the sanitary wet well of the 1st Avenue Pump Station and convey wastewater flow through a PVC force main to the Beaver Channel Interceptor. The four  submersible, non-clog, centrifugal pumps provide a firm design pumping capacity of about 25 mgd. The two small pumps have a capacity of 6.46 mgd, each and the two large pumps have a capacity of 12.38 mgd, each. It should be understood that the sanitary pumps are currently set to restrict flow to a maximum of 16 mgd due to the current capacity of the downstream receiving sewer. Each pump includes a quick connect and guide rail system and is centered under an aluminum floor door for installation/removal. The discharge line for each pump contains an isolation plug, swing check, and air/vacuum release valve. All fourpumps are driven by variable frequency drives (VFDs).

Pump control is in accordance with liquid level in the wet well as measured by a submersible level sensor. Float-tilt level switches control pump start/stop. The operator can adjust the pump settings, desired wet well level and alarming at the remote HMI, or locally at the OIT in the Pump Station Electrical Room. Oil in each pump's oil chamber lubricates and cools the mechanical seals. Lubricants require periodic replacement.  

 

Variable Frequency Drives6
The four sanitary influent pumps are equipped with variable frequency drives to provide adjustable speed operation of the sanitary sewer pumps. This allows pump speed to be adjusted with varying  wet well level.
CSO Pumps6

 

During certain wet weather events, liquid level in the influent channel will rise above the CSO weir wall elevation and flow will enter the CSO wet well. Two CSO pumps are located in the CSO wet well of the 1st Avenue Pump Station and provide pumping capacity for peak wet weather flows. CSO flow is pumped through an existing steel pipeline to the Mississippi River. The two submersible, non-clog, centrifugal pumps, have a design pumping capacity of 16.5 mgd, each.Each pump includes a quick connect and guide rail system and is centered under an aluminum floor door for installation/removal. The discharge line for each pump contains an isolation plug, swing check, and air/vacuum release valve.

Pump control is in accordance with liquid level in the wet well as measured by a submersible level sensor. Float-tilt level switches control pump start/stop. The operator can adjust the pump settings, desired wet well level and alarming at the remote HMI, or locally at the OIT in the Pump Station Electrical Room. Oil in each pump's oil chamber lubricates and cools the mechanical seals. Lubricants require periodic replacement.  

Reduced Voltage Solid State (RVSS) Starters6
The CSO 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.
CSO Sump Pump6

 

After the occurrence of a CSO event, the submersible sump pump located in the SW corner of the CSO wet well can be used to pump down the wet well when the station is otherwise out of service. The pump can be placed in an AUTO mode at the pump control panel or operated manually. If in AUTO mode, the lower switch is the pump stop, the middle is the pump start, and the upper is the high level alarm.
Wet Well Level Monitor6

 

The liquid level in the sanitary and CSO wet wells are measured by submersible type level sensors. Float-tilt level switches accompany the submersible level sensor and control pump start/stop,  as well as high-high and low-low wet well level alarms.

A low-low detection in either wet well discontinues pumping via hardwired interlock. A high-high level in either wet well sends an alarm which can be viewed locally at the OIT in the Pump Station Electrical room or at the HMI in the Clinton WWTP Control Room.

Flow Monitoring6
A magnetic flow meter is provided in both metering manholes (sanitary sewer and CSO) to monitor the discharge from the sanitary sewer pumps and CSO pumps. Flow data is sent to the PLC which transmits the information to the HMIs for display of totalized and instantaneous flows
Sanitary Channel Grinders6

 

The 1st Avenue Pump Station includes two channel grinders located in the influent channel upstream of the sanitary wet well. The smaller channel grinder (GRD-01) has a capacity of 7 mgd and the larger channel grinder (GRD-02) has a capacity of 18 mgd. The electrically driven system includes an intermeshing cutter which reduces the particle size of raw wastewater solids, protecting downstream pumping equipment.
CSO Influent Manual Bar Screen6
A 16 foot long stainless steel coarse bar screen is located in the influent channel, upstream of the CSO wet well. All flow entering the CSO wet well passes through the manual bar screen. The purpose of the bar screen is to prevent oversized trash, debris, and other floatables from entering the CSO wet well. The bar screen must be manually cleaned.
Slide Gates6

 

Two manual operated stainless steel slide gates are located in the influent channel of the 1st Avenue Pump Station. The gates allow each of the channel grinders to be isolated for maintenance activities.
Radio Transceiver6

 

The 1st Avenue 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. In addition, local control of the facility can be accomplished using an Operator Interface Terminal (OIT) at the main control panel located in the Electrical Room. All the site operation screens will be functionally identical between the HMI and local OIT.
Emergency Engine Generator6

 

A diesel powered emergency engine generator is located adjacent to 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 located in the pump station electrical room and automatically switches operations over to standby power in the event a power outage is detected. It is recomm ended 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: 6/15/2021 6:10:05 PM
Version 3.0.1