1981-05-04 Septic System Design Report

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Septic Testing, McCleary Property May 5, 1981 page 2 6. Inherent in Ue design proposed are individual separate septic tanks and holding tanks for each residence. These should be loca,.ed on the individual lots so that the only pipe(s) crossing lot lines are the three pres..sre distribution manifolds from the residences. 7. The proposed design meets criteria for a mound system within the sheet flow floodpl.ain area. 8. Further items needing tc be addressed include: a) Can the proposed layout be constructed within the applicant's proposed lot line arrangement and still allow for a driveway on the common lot? A scaled site plan should be submitted for review, showing all proposed improvements. b) What are the provisions for an alternate drainfield site? If none exists, I would recommend that if failure occurs, the holding tank system for all waste would be required. c) Subheading (3.) of my memo of 1-21-81, still needs to be addressed. (Ownership and responsibility for maintenance and repair) For the record, the technical justification for allowing a graywater mound/holding tank system on this site is a) adequate area exists for a mound system; b) adequate percolation rates were demonstrated where the water table permitted; c) the proposed system is designed to compensate for the high water table. (Note that, normally, no system would have been allowed in this area, and holding tanks as well as the mound system are a variance to the on -site ordinance).d) the holding tank/graywater combination will reduce the on -site treatment required for: BOD - by approximately 50% N - by approximately 80% P - by approximately 50% Total water use by approximately 40% (Based on Manual of Gray Water Treatment Practice Table 8 p. 77) Hence the system will not have as great an impact on the soil/water system of the area as a total mound system would, a^d should not create any undue pollution or health problems for the area.