1985-08-26 Septic System Design Report

Home Browse Search

Lot 2, Block 1 Peres PB21 thru PB:5. Borings BB21 thru BB23. Average• pert s for bath Frimary and alternate sites are. acceptable. SloI)cs nearly level at the tested sites, ranging from 0 to 3%. Mottling indicated below 21, with actual water tab.e at 3.2 to 4.21. A standard mound system should be used due to the presence of sh-illow saturation zones. Lot 3, Block 1 Peres PB31 thru PB26. Borings BB31 thru BB33. Slope, in the primary site are approximate?y 6-88, on a slight flattening Of the 10-121 slopes surrounding it. Borings in the primary site indicate 1 to 2 ' of loamy topsoil over a 6" layer of organic clay topsoil over r. plastic sandy clay. Actual water table at the primary site was bel, 5'. However, the high plasticity indi a heavy clay that i bably saturated. The secondary site mottled below 1.5 '- an actual saturated zone at 1' depth. Coupled with a s. the secondary site i3 marginal for a round system and a .ire at least 2' of sand base as part of the design. I suq�, hata standardpresaure mound system be required for .both sites with addea sand depth fur the secondary system. Please note that this lot is the most tenuous in the subdivision in terms of slope and soils consideration for using a mound system. Should a propo:��d house location encroach on either of the tested sites, careful review and possible additional +.esting will be neeled to ensure that a mound can still be used. rnu site does not appear capable of supporting any kind of a trench system. Lot 4, Block 1 Peres PB41 thru PB46. Boring- 9B41 thru BB43. Slopes average 58 - 7% overall. Borings indicate actual water table at 4' with mottling at a depth of 3-4' for the primary and 2' at tn, --condary site. Perc rates were fairly uniform throughout these tested .sites. A depression/drainageway to the immediate south of the tested sites must be avoided during construction of the systems. I .could recQMQ&g9 A standard pressure mound for both site. Lot 5, Block 1 Peres PB51 thru PB56. Boring:, BB51 thru BB53. dopes are 3% to 6% overall. Mottling at the primary site started at 2.7 to 3.5' with actual water table at 3.7 to 5.0'. This site is acceptable for a standard mound system. The alternate site hag a perc rate considered too slow for any system by code. However, close scrutiny shows that the peres were taken at depth in the sandy clay subsoil, not in the topsoil. In general, throughout the entire subdivision the testing done at a depth of 12", in the topsoil, indicates acceptable percolation rates, with testing at 24" or more indicating slower, marginal perc rates. In my opinion, this site is no different than most of the others, and would have an acceptable perc rate if tested at the 12" depth in the :.andy loam topsoil. No further testing should be required; a mound system if; recommended. ' r=