01-11-2016 Council Packet - Laserfiche WebLink

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Type I System 1.Type I systems have specific design requirements that have been used and tested for many years so the longevity and performance are consistent. 2. A Type I system requires a minimum separation of 12” from the seasonal high water table to grade. 3.The Septic Tank requirements are the same for both Type I and Type III. 4. There are design tables in the code for the sizing of all types of septic systems . 5. A maintenance program is to be devised by the de- signer for every type of septic system . 6. Type I systems can be Mounds, Trenches, Pressure Beds, or At Grade systems. Type III System 1.Type III systems deviate from this known criteria so it’s performance is not as well known. Measures are usually taken to compensate for the departure from this criteria such as replacing soils with sand and or sizing the Type III system the same size as a Type I. 2. A Type III system is not required to have a 12” sep- aration from the seasonal high water table to grade. A minimum of 36” from the seasonal high water table to the treatment media is required for both Type I and Type III. If the separation distance to grade is less than 12 “ this means it will take more materials to construct the system than a Type I. 3. Septic Tank requirements are the same for both Type I and Type III. 4. If a Type III system needs to use values for sizing less than a Type I system a means of restricting devic- es that do not allow loading in excess of the smaller allowable values is required. Alternate sizing values can also be proposed but need to be approved by the City. 5. A maintenance program is required for a Type III system. Also a mitigation plan addressing what to do if the system fails or if portions of the system fail, who is responsible for the work and costs involved in cor- recting these issues. 6. Type III systems are usually Mounds but do not have to be Mounds Comparison of Type I vs Type III septic systems Based on Minnesota State rules