1984-10-30 Septic System Design Report

Home Browse Search

Ohl', Hin,,••r Sijhdivision 1'ay(- 4 Lot 2, Block 1 Peres PH21 thru PB26. Borings BB21 thru BD23. Average perc rates for bDth Frimzry and alternate sites are acceptable. Slopeq are nearly level at the tested sites, ranging from 0 to 3%. Mottling indicated below 2', with actual water table at 3.2 to 4.21. A standard mound system should be used due to the presence of shallow saturation zones. Lot 3, Block 1 Peres PB31 thru P1326. Borings B031 thru BB33. Slopes in the primary site are approximately 6-8%, 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 a plastic sandy clay. Actual water table at the primary site was below 51. However, the high plasticity indicates a heavy clay that is probably saturated. The secondary site was mottled below 1.5 feet with an actual saturated zone at 1' depth. Coupled with a slope of 10% the secondary site is marginal for a mound system and would require at least 2' of sand base as part of the design. I suggest that a standardpre3sure mound system be required for both sites with added sand depth for the secondary system. Please note that this lot is the most tenuous in the subdivision in turms of slope and soils consideration for using a mound system. Should a proposed house location encroach on either of the tested sites, careful review and possible additional testing will be ncedel to ensure that a mound can still be used. The site does nog appear capable of supporting any kind of a trench system. /A,u t 4, Block 1 ,/ Ileres PD41 thru PUIG. 13crings 7J841 thru U1343. :;lopes average 514 - 71 overall. Lo_i.ngr. indicate actual'water table at 4' with mottling at a depth of 3-4' for the primary and 2' at the secondary site. Pere rates wore fairly uniform throughout those tcc;ted sites. A depres3ion/drainageway to the imi-iiediate south of the tested sites must be avoided during construction of the systems. I would ` recommend a ~standard pressure mound for both sites. Lot 5, Block 1 Pere; P1351 thru 11D5G. Lorincjs LD51 thru L1353. :lopco arc 31 to 63 overall. Mottling aL Liao primary site :started at 2.7 to 3.5' with actual water table at 3.7 to 5.0' . This; site is; ac.cepcat)le for a standard mound sy:,t--;m. The alt-crnate site has a f.('.rc rate cunGidered too slog for any sysLc.rn by code. do:jevcr, close scrutiny shows that the peres were tat -on at lepth in the sandy clay subsoil, not in the L opsoil. In c1cneral, throughout the entire subdivision tho tcstinrl done at a depth of 12", in the tripsoil, indicates acceptable percolation rates, with tcstincf at 24" or more indicating slower, marginal perc rates. In my 01)inion, this site is no different than must of the others, and would have an acceptable Lore rate if tested at the 12" depth in the :randy loam top:;oil. No further 'te:t;tincj shuu1,1 b(( rr-rluirorl; a mound-.yr;tc.rn if; recc)mrnended.