This Excel Spreadsheet was designed by the Hendricks County Health Department and is utilized for plan review of proposed onsite wastewater disposal systems. The information on this site is provided as a public service only. The information here is unofficial and is not a valid reference for any legal purposes. The spreadsheet design is based upon Indiana Administrative Code 410 IAC 6-8.3. It is intended to provide guidance and assistance in designing a subsurface gravity flow trench system, a subsurface dosed trench system, a sand mound system, a Presby or an ATL. It does not cover every possible situation. The Hendricks County Health Department holds no responsibility and cannot be held liable for any damages from the use of this document.