RESIDENTIAL SEPTIC PUMP SPREADSHEETS

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1 RESIDENTIAL SEPTIC PUMP SPREADSHEETS Matt Gavelek, PE St. Joseph County Health Department February 19 th, 2014

2 Two Methods Spreadsheet Facts Example Benefits Going Forward 2

3 2 Methods of Pump Selection DESIGN POINT OPERATING POINT Pump does not perform at the design point 3

4 2 Methods of Pump Selection DESIGN POINT Only need 1 calculation Approximation Open to interpretation Code checks are a guess OPERATING POINT Many calculations Precise Non-debatable Code checks are precise Before Personal Computers Excel Spreadsheet = No Calculations 4

5 Operating Point Method Operating Point = actual performance of system Operating Point is the intersection of the system curve and pump curve The pump only operates at the Operating Point, not the Design Point 5

6 System Curve System Curve = the pressure (head) the pump needs to push against at various flow rates. System Curve = graph showing the Total Head (aka System Head) for many flow rates. Hard by hand, easy with computers Total Head has 3 parts: Elevation difference Friction loss Desired pressure (pressurized distribution) 6

7 Pump Curve Pump Curve = the height the pump can lift a column of liquid at certain flow rates. Pump Curve is specific to each pump s design Pump speed, motor, impeller size & shape, volute size and shape, etc. Pump curves are available from pump manufacturers. 7

8 Spreadsheet Facts 3 Excel Workbooks (spreadsheets) Flood Dose Pressure Trench Elevated Sand Mound Takes 2-4 Minutes to input data Requires little understanding of Excel (ver and up) Pre-programmed & user defined pump data The spreadsheet takes 7 data points from a pump curve and creates a pump curve Verify the Pump Curve The curve is current with pump manufacturer s website Make sure the curve isn t wavy The R 2 value should be above 0.97 Two Methods Spreadsheet Facts Example Benefits Going Forward 8

9 Spreadsheet Facts 4 Worksheets (tabs) 1. Read Me First User agreement & brief instructions 2. Design Check Input, Analysis & Checks Fill out tan colored cells IAC General engineering 3. Help Very detailed explanation of everything! 4. Calculations not for users Two Methods Spreadsheet Facts Example Benefits Going Forward 9

10 Spreadsheet Facts Inline Residual Head (lateral pressure) In Total Head equation - commonly thought of automatic 3 of head Not automatic 3, based on geometry & operating point Actually based on three factors: Perforation discharge rate = Operating flow rate (gpm) / # of holes Hole size Inline Residual Head is not an input for spreadsheet The spreadsheet uses the # of holes, hole size and operating flow rate to determine the Inline Residual Head Two Methods Spreadsheet Facts Example Benefits Going Forward 10

11 Flood Dose Example A very experienced installer submitted a Design Point Method 4 Bedroom - Designer picked 60 gpm from IAC Table VII range of gpm Designer used 3 force main because they like larger lines for larger # of bedrooms Picked a pump that s above the design point Does this comply with IAC 6-8.3? 11

12 Flood Dose Example Input design data into Flood Dose Spreadsheet 12

13 Flood Dose Example Automatic Analysis Pump s Sweet Spot Design Point Operating Point Terrible Design Reduces pump s life span & very inefficient 13

14 Flood Dose Example Automatic Code Check Fails IAC s requirement for flow rate (Table VII). Fails 2 general engineering checks System curve is flat look into a smaller force main. Try 2 14

15 Flood Dose Example Use Spreadsheet, change force main size to 2 Pump s Sweet Spot 15

16 Flood Dose Example Automatic Code Check = GOOD! Explained problem to designer/installer. 16

17 Flood Dose Example Original Submittal Submitted Revision Not code compliant Terrible design Reduced longevity of pump Very inefficient Code compliant Better design Better pump longevity More efficient 17

18 Benefits of Spreadsheets Produce Better Designs by: Giving the spreadsheets to your contractors! Saves them time by eliminating re-submittals Utilizing the operating point method more precise Including general engineering checks that are not in code: Operating point placement Sweet spot (middle 1/2-1/3) increases life span & efficiency as explained by Alice at IEHA s Fall 13 Conf. Pump run time (short run times reduce longevity) Lateral and manifold sizing checks Calculating effluent velocity Helps to keep force mains clean if velocity is above 2 ft/s Watches out for large velocities 18

19 Benefits of Spreadsheets Saves TIME! The spreadsheets: Requires 2-4 minutes of input Perform ALL calculations, instantly Perform ALL checks to IAC code, instantly Flood Dose = 5 checks Pressure Trench = 8 checks Elevated Sand Mound = 14 checks Recommends solutions ( Tips ) when code is not met 19

20 Benefits of Spreadsheets Education Gives users a working knowledge of pump hydraulics. Help page is HELPFUL! Here are excerpts: 20

21 Going Forward Consider using the spreadsheets in your county These spreadsheets are free and for the public Recommend distribution to contractors ISDH will the spreadsheets to LHDs Spreadsheets & videos will be posted here: For spreadsheet questions, see the Help tab 99% of questions will be answered by the Help tab Otherwise, contact Alice Quinn The Sump & Sewage Pump Manufacturers Association (SSPMA) provided comments which were implemented into the spreadsheets. Special THANKS to Marc Nelson (St. Joe Env. Director), Dr. Don Jones & Alice Quinn QUESTIONS or COMMENTS?? 21