1981-05-04 Septic System Design Report

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Septic Testin„ McCleary Property May 5, 1981 page 2 6. Inherent in the design proposed are individual separate septic tanks and holding tanks for each residence. These should be located on the individual lots so that the only pipe(s) crossing lot lines are the three pressure distribution manifolds from the residences. 7. The propov- design meets criteria for a mound system within the sheet flow flcodplain area. 8. Further items needing to be addressed include: a) Can the proposed layout be constricted within the applicant's proposed lot line arrangement an,1 still allow for a driveway_ on the common to ? A staled site plsn should be submitted to 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 wculd he required. c) Subheading (3.) of rry memo of 1-21-81, still needs to be addressed. (ownership and responsibility for maintenance and repair) For _'e 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 F :rrc,itted; c) the proposed system is d-signed to com;,ersate fcr 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 ate a variance to the on -site ordinance) d, the holcin3 tank/graywater combination will reduce the on -site trpgtment required for: BOD - by approximately 50% N - by approximately 80% P - by approximately 50% Total water use by approximately 40% (Based on Manual of Cray Water Treatment Practice Table 8 p. 77) Hence the system will not have as great an imp:;ct on the soil/water system of the area as a total mound system would, and should net create any undue pollution or health problems for the area.