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Residential Septic Pump Spreadsheets

Introduction & Overview

These spreadsheets are available to the public for the purpose of checking a septic pump design for compliance with 410 IAC 6-8.3. They are not to be used as a designer’s sole design resource. Also, pump manufacturers will size pumps for free, but they do not verify that a septic design complies with IAC 6-8.3 requirements. Therefore, these spreadsheets were created as a free tool for designers and regulators to verify code compliance.

The spreadsheets utilize an accurate method, the Operating Point Method, to check pump design. With a few minutes of input, the spreadsheets automatically: calculate the pump and system’s operating point, check that operating point for compliance with IAC 6-8.3 as well as general engineering principles, and offer tips to remedy failed compliance. The spreadsheets yield precise results while saving time.

Brief Instructions

The spreadsheets are very user-friendly and work for Excel versions 2007 and up. Read the “Read Me First” tab of the spreadsheet. The user agreement must be accepted for the spreadsheet to function. The “Design Check” tab is where information is input, analysis is displayed on a chart, checks are performed, and recommendations are made. All cells with tan coloring must be filled out in order for the spreadsheet to perform correctly. Cells that are not colored tan cannot be edited. The “Design Check” tab can be printed as a hand-out. The “Help” tab has a detailed explanation of everything in the “Design Check” tab. Nearly all questions can be answered from the “Help” tab. The “Calcs” tab is the calculation engine of the spreadsheet and does not require input.

These spreadsheets account for the St. Joseph County Ordinance and follow a slightly different method for calculating Total Head than IAC 6-8.3. The St. Joseph County method results produce similar to the IAC method.

The designer has the option of submitting the applicable spreadsheet or submitting the previously utilized hand-calculation worksheets: Flood Dose Worksheet, Pressure Trench Distribution Worksheet, Elevated Sand Mound Worksheet. If the worksheets are submitted, then they will be checked using the spreadsheet. If a designer seeks pump-related design guidance, then they may use the Elevated Sand Mound Design Manual created by ISDH.

The spreadsheets perform two different types of checks: IAC Code checks and general engineering design checks.

A pump design will be rejected if any of the IAC code checks fail, except for the following situations:

  1. Only applicable to Elevated Sand Mounds – Inline Residual Head between 2.5’ and 4.0’.
  2. The dose-volume is within 10% of the required dose volume. This can be waived if a larger dose volume is required to pressurize laterals for a bed or deep cut backfill applications.

A pump design will be rejected if any of the following general engineering checks fail:

  1. The operating point is placed in a “Questionable” or “Re-design” region. Those regions occur when the operating point is located outside of the middle 67-100% of the pump performance curve.
  2. Pump run time is less than 1 minute.
  3. Pressure Trench & Elevated Sand Mounds – the dose is less than 7 times the lateral volume.

Help with Spreadsheets

First, make sure all instructions are followed. Secondly, make sure all tan-colored cells are filled out and the user agreement is accepted. Thirdly, nearly all questions can be answered by thoroughly reading the “Help” tab.