pump station considerations for a simple duplex station discharging into a combined regional force...
DESCRIPTION
Project Background Private development client Development includes two large retail buildings, service station, bank, and general commercial No gravity sewer service in areaTRANSCRIPT
Pump Station Considerations for a Simple Duplex Station Discharging into a Combined Regional
Force Main
Rachel Rausch, EIT
Site Location
Bluffton, SC
Project Background
• Private development client
• Development includes two large retail buildings, service station,
bank, and general commercial
• No gravity sewer service in area
Project Background
Unique Design Considerations• Donation of project to Beaufort Jasper Water and Sewer
Authority (BJWSA)
• Little topographical variability on site
• Deep wetwell
• Site pump station will pump into 16” combined regional
force main Unknown conditions in regional force main
Design Solution: Data Collection
• BJWSA Standards
• Force main record drawings
• Force main operating conditions
• Operating pressure
• Flow
Design Solutions: Calculations• Wastewater Flow Estimate
• Site Storage Volume
• Force Main Operating Conditions
• Choosing Pumps
Design Solutions: CalculationsWastewater flow from site:Peaking Factor=4Qpeak=92.4
BJWSA storage volume requirement:
Storage volume in site MH and pipes > 24 hour volume from site
Pump SelectionExisting force main conditions analyzed
• Regional Force Main Pump station on• 1,000 gpm @ 70’ TDH
• Regional Force Main Pump Station CP-67 off
• No flow in regional force main
• Two C factors analyzed for each system curve
System Curve-Pumps On
0 200 400 600 800 1000 12000
50
100
150
200
250System Curve-Regional Force Main Pumps On
TDH C1 MIN [FT] TDH C1 MAX [FT] TDH C2 MIN [FT] TDH C2 MAX [FT] PUMP CURVE #1
PUMP CURVE #2 PUMP CURVE #3 PUMP CURVE #4 PUMP CURVE #5 PUMP CURVE #6
Flowrate (gpm)
TDH
(ft)
Design Point:310 gpm at 102’ TDH
Hazen-Williams C Factors:C1=110C2=130
System Curves-Pumps Off
0 200 400 600 800 1000 12000
50
100
150
200
250
300
350System Curve-Regional Force Main Pumps Off
TDH C1 MIN [FT] TDH C1 MAX [FT] TDH C2 MIN [FT] TDH C2 MAX [FT] PUMP CURVE #1
PUMP CURVE #2 PUMP CURVE #3 PUMP CURVE #4 PUMP CURVE #5 PUMP CURVE #6
Flowrate (gpm)
TDH
(ft)
Design Point:410 gpm at 96’ TDH
Hazen-Williams C Factors:C1=110C2=130
Pump Selection
Other Calculations
• Cycle time
• Buoyancy Calculations
• High groundwater table
• Deep wetwell, approximately 24 feet deep
Final Pump Station Layout
Project Status• BJWSA Approval• Construction Status
Questions?
Lessons Learned