01-16-1996 Planning Packet - Laserfiche WebLink

Home Browse Search

n Water table is defined as "the highest elevation in the soU where aU voids are fiUed with water, as evidenced by presence of water or soil mottling or other infonnation". In the State of Minnesota, soil mottling has become the key factor m detenmmng the highest level of seasonal saturation in the soil. In Orono's loam and clay loam soils soil mottling and seasonal samration are commonly found from 2 ’ to 5' below the ground surface. In order to meet the 3 ’ separation requirement, a majority of new septic systems are mounds, which maintain the 3 separation. The use of soil mottling ior determining seasonal samration is subjective at best, but is the onlv practical method identified by the State for determining seasonal samration. However, in some years samration may not occur at the mottlmg level, and in other years saturation may occur at the mottling level for only a few days, weeks or months in a given year. The State has taken the position that even though the system might be too close to the water table for a short period dunng any given year, that system is not conforming. Verv few septic systems in Orono are failing at any given time, perhaps 3-5% or 1 in'25. However, as many as 500-600 of the 1150 existing systems are estimated as fitting the definition of "non-conforming". While these may treat sewage quite adequately most of the time, during some periods they may not. 3. Evaluation Methods. Each neighborhood was evaluated in terms of soil and water conditions, proximity to lakeshore or other water bodies, and lot sizes. Within each neighborhoot^ individual svstems were analyzed to determine system type (trench, mound, bed or cesspool), system condition (working, marginal or failing), conformity with 3 separation requirement (conforming or aonconforming). whether the system is m the designated "Shoreland" district, and whether or not an alternate drainfield site is available. Note that in analyzing system conditions, systems exhibiting no surface discharge and generally in working order were considered as "working"; systems obviously discharging to the surface were considered as "failing"; and systems^with a drainfield area saturated but not discharging were considered as "marginal". It is, therefore, possible and quite common to have a system that is working but is still non-conforming. 4 Table 2 - Summary of Systems by Neighborhood (Page 8) 5. Individual System Data and Neighborhood Maps (Pages 9-33) i