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r <br />n. Analysis of need <br />A. Existing Septu: Systems Inventory and Analysis <br />1. Overview of the Problem <br />Of approximately 1,150 septic systems in Orono, 75% make use of draintield <br />trenches or beds ranging in depth from 1' to 3 ’ below the natural ground surtace. <br />Based on localized testing and review of the soil sur\'ey, it is estimated that trom <br />one-half to two thirds of these systems do not meet the required 3 ’ separation from <br />seasonal zones of samration. By definition, these systems are nonconforming <br />according to current state and local codes, and must be upgraded. <br />In most cases, upgrading will require replacement of a trench or bed system with <br />a mound system at a cost of approximately $8,000 to $10,000 per unit. This cost <br />of replacing septic system approaches the $12,000 to $20,000 per unit cost of <br />installing municipal sewer in Orono. <br />When faced with the prospect of wholesale septic system replacement, the City <br />chose to place a moratorium on system repairs and study whether sewer installation <br />is more appropriate than system upgrades for specific areas or neighborhoods. City <br />staff subsequently identified ten existing residential neighborhoods of high density <br />or close proximity to lakeshore. These areas were analyzed to determine whether <br />they have the capability of repairing/replacing septic systems. Current system <br />conditions were analyzed, and cost estimates for municipal sewer were developed. <br />None of these ten areas are currently within the MUSA. Six ot ten were originally <br />identified in Orono’s 1980 Comprehensive Plan as "Rural Housing Clusters" <br />developed at densities greater than the 1-per 2 acre standard. It was noted in the <br />1980 plan that these neighborhoods were not at that time experiencing septic <br />problems but would be monitored. White the incidence of failure has not increased <br />in these neighborhoods, new definitions of "non-conforming systems" and the <br />requirement to upgrade such systems has become a serious concern. <br />2. "Nonconforming" Versus "Failing" Systems. <br />In 1989, MPCA Rules Chapter 7080 were revised to include in the definition of <br />nonconforming systems, "systems with less than 3' of unsaturated soil or sand <br />between the distribution device and the limited soil characteristics . <br />regulation defines the limiting soil characteristics as "those soil characteristics <br />which preclude the installation of a standard system, including evidence of water <br />table Water table is defined as "the highest elevation in the soil where all <br />voids are filled with water, as evidenced by presence of water or soil mottling or <br />other information".