Evaluation of Jackson and Saylor Sanitary Sewer Lift Station During July 23-24, 2010 Storm Event. Presented by:

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1 City of Elmhurst Evaluation of Jackson and Saylor Sanitary Sewer Lift Station During July 23-24, 2010 Storm Event Christopher B. Burke Engineering, Ltd. Presented by: Christopher B. Burke, PhD, PE, D.WRE, F.ASCE

2 General Facts About Jackson and Saylor Sanitary Sewer Lift Station Improvements were made to station in 1988 Four submersible pumps (2) Pumps Hp (2) Pumps Hp Depth of incoming sewers is about 15 ft. deep Has a comminutor to break up solids Variable frequency drives to match pump speed to incoming flow Indicator lights on exterior for pump run and generator run (recently installed) Manual bypass valve diverts flow to Jackson St. storm water pump station Standby power provided by natural gas generator located within the building Alarm system communicates with staff via radio transmission

3 The service area for the Jackson and Saylor Sanitary Sewer Lift Station is highlighted below.

4 The sanitary force main exits the west side of the station and goes north on Saylor to a 48 gravity interceptor sewer on McKinley Ave. The 48 interceptor sewer goes west to the City of Elmhurst Wastewater Treatment Plant (WWTP) which is located on the east side of Route 83 at Crescent Ave.

5 There is a bypass valve within the station that will send sewage west on Jackson St. to a 24 gravity storm sewer at Hillside Ave. The sewage is then conveyed to the Jackson St. storm water pump station where it is discharged to Salt Creek.

6 The Station is equipped with a Supervisory Control and Data Acquisition (SCADA) system which relays various types of information to the City s WWTP where the data is received along with data from the other 21 lift station/pump stations that the City monitors and maintains.

7 When there is a failure at a pump station an alarm signal is automatically sent to the master SCADA station at the WWTP. Appropriate City staff are also notified via telephone of an alarm condition at a specific pump station.

8 Steps taken to determine if the Jackson and Saylor lift station was in operation during the July 23-24, 2010 storm event: Three site visits by Mechanical Engineer and Principal City staff interviews Plan drawing review Witnessed generator operation through simulated power loss Witnessed simulated pump failure and resultant SCADA alarms Observed new indicator lights for pump run and generator run Reviewed the operation of the SCADA system at the WWTP Reviewed SCADA alarm history for July 23-24, 2010 Reviewed SCADA system historical data for the station including pump run time, station flow, wet well water levels, and generator status Performed a diagnostic test of the SCADA system with City staff to determine if pump failure alarms function as designed, and SCADA alarm screens indicate what is actually happening at the station. Reviewed sanitary and storm sewer atlases Reviewed storm water management reports

9 Findings Under normal operating conditions, the SCADA system will show wet well elevation, # of pumps on, station flow, pump run time, generator status, intrusion alarm, PLC status, and the ON-OFF elevations of the pumps.

10 When pumps are taken out of service, the SCADA system will indicate pump failure as shown below from a pump failure simulation. Similar alarms will indicate power failure, generator running, high water alarm, intrusion alarm, etc.

11 During the July storm event, the SCADA system collected the data shown below: The green line shows pump discharge flow out of the station and the blue line shows water level in the wet well.

12 The below screen is from approximately the same time frame on July 23 rd and 24 th, The green line shows the discharge flow from the station, the blue and red lines are the high flow pumps operating. The black line shows the low flow pump operating in bypass mode at approx. 1:30am on July 24 th. The bypass operation is a manual operation performed by City staff after the wet well level reaches an alarm condition and notifies staff.

13 Other Findings The lift station was operating using ComEd electrical service (backup generator was not required). As expected, generator operation is noisy and can be heard from a long distance away The sound of the submersible pumps could be heard from a distance of about 2-3 ft. from the door when multiple pumps were operating. When only one pump was operating the sound of the pumps was barely discernible. City staff initiated the bypass mode at approx. 1:30am July 24 th by manually opening and closing selected valves and manually turning the bypass pump on. The high flow pumps turned on at approximately 10:30pm on July 23 rd as called for by the wet well water levels and ran continuously through approximately 3am on July 25 th. All stations report via radio transmission to Master SCADA computer at the WWTP. Stations are monitored continuously. The SCADA systems at each station have battery backup if a power failure occurs.

14 Conclusions: Jackson and Saylor Sanitary Sewer Lift Station was operating throughout the July 23-24, 2010 storm event It was running at capacity which was exceeded sometime after midnight The bypass pumps were started about 1:30 a.m.