06-28-1993 Council Packet - Laserfiche WebLink

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establish a sewage treatment system setback at a distance closer to the river than the principal structure setback. Second, the location of the sewage treatment site should be related to the management objective of each river class, the expected recreational uses of the river (which is a component of the river classification system) , and the inherent capabilities of soils or building sites adjacent to the watercourses to effectively treat the effluent loads in the drainfield. For example, a system setback of 150 feet for Remote river segments accomplishes the management objective as stated earlier because drainfield location will ensure that a high degree of effluent absorption (phosphorous) and dilution (nitrates) occurs between the system location and the watercourse. This in turn maintains and enhances water quality which is important for the Remote river class and the recreational use expectations and activities associated with the class(f'shing, swimming, recreational boating). The soils capabilxty for this class can be generalized as moderate to poor since most of the Remote river segments are in areas of either shallow soil depth to bedrock or high seasonal ground water tables, which are both limiting factors in siting sewage treatment systems. For these ^ reasons, a sewage treatment system setback of 150 feet is needed and reasonable. The same rationale also applies to the Forested and Transition river segments, with the only difference being a sewage system setback standard of 100 feet which is related to the reduced structure setback provision for these two classes. These watercourses generally receive a high amount of recreational use and preservation of water quality is important. These segments generally have higher flows than Remote river segments and therefore would have better assimilation and dilution capabilities, justifying the slightly reduced setbacks for the placement of on-site sewage treatment systems. Sewage treatment setbacks for Agricultural, Urban and Tributary segments of 75 feet are reasonable since they relate to the proposed structure setbacks. They are also reasonable from a water quality aspect since Quality of these segments is primarily influenced by other factors such as agricultural runoff and urban point and no point pollution sources. Most of the Urban and those ^ Tributary segments having concentrated development alreaa> have municipal sewer service available or installed and the sewage setback discussion is no longer relevant.