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Home My WebLink About1982-10-27 Septic System Design ReportFOR - CUP -T(, NNni-Rc-,O l �hSEMFJa � FlR EL�v, QeS.d 71:tJU6(ti '4w S6wEfL 13L.T3t: (.#,.* EL .483.0 loco lcaoo GAi. GAL P4NV 11k, We Poem S6P,)c SCvt( SjA, Y1A I►1 -- 882.3 t-1 o T T ci Sc flL_. -'V-) tiLS 06 -SITE SEWrtGE *V?-F-A-rME,,-) C SYSTaV\ L�� 3 , "PSLk,- l CouN0 VAfUO(L C) 7 j> C-" ECJ-- V{lUlE 1 IF Items; ALLU S{1UlJLD VSC_ WIT NAIQ TtA -. "Mouwt>" 'to pP_E.vE1-) i FR.EEZ11,3 UR -10C 'DG 2t0pS �I's u;(L- . 3 J F� ►.1T] �R�E� S N A Ly T� 12.11 M 1 0 -D677-r 4 ,) 'Pu Ih T� 10 STA ► 1 b ►•� �- h +._�_ A I SC. N a rt.G c R T C, c ft S r 'Loa �,) {' Cst;�� CAPAC.tT� PLr3ov E �t-rz2R✓� Sba q`L gG LErt6T Goo C.OtvS T t, UC -'r to C.4 ALL COV F=6kt'l To TZ),LTA ILS � S PtLIFIChrlo� C�vTLt,u E_t� tN TK E Ri �L12tLG.UTt..1; Q FOSZCE Tt1E OZ.ouU 'pN SITE S&.AJ#46 ►RFAi N6U� �Y�►c+-� DESIGt) �"�RNuAL." -'V-) tiLS 06 -SITE SEWrtGE *V?-F-A-rME,,-) C SYSTaV\ L�� 3 , "PSLk,- l CouN0 VAfUO(L CITY OF ORONO GENERAL CONSTRUCTION REQUIREMENTS MOUND DRAINFIELD SYSTEM TO BE USED WHERE: Seasonal perched water table is between 2 feet and 4 feet below surface. Percolation rate in top 12" of soil is faster than ()o MPI. Percolation rate in subsoil but above water table is faster than 120 MPI. Where percolation rate' is 60-120 MPI, depth to groundwater shall be at least 3' and slope must be no more than 3%. Where percolation rate is 30-60 MPI, depth to groundwater shall be at least 2' and slope must not exceed 6%. If percolation rate is faster than 30 MPI, depth to groundwater shall be at least 3' and slop:. must not exceed 6-12%. CONNECTION TO HOUSE House to tanks may be PVC (ASTM D-3034 or better), cast iron or clay tile. PVC should be sand -bedded in flat runs over long distances. No outside air test required but joints must be tight. TANKS Two (2) precast concrete tanks are required. Mitt. size 1000 gal. and 750 gal.; we recommend 2 1000's. Tanks must have 20" manhole riser to within 12" of final grade, and at least one 4"-6" inspection stack to surface. Baffles must be acid resistant and may be plastic, fiberglass, or precast with tank. DRAI14FIELD Mound consisting of 12-24" layer of sand on plowed, chopped, or otherwise scarified natural surface soil. 12" rock bed on top of sand layer, 10' maximum width X length dependent on water use. Distribution pipe is laid in too 3" of rock. Cover rock bed with straw or hay AND building paper. A layer of sandy loam 0-12" thick shou?d be placed over the covered rock bed and a 6" layer of topsoil then placed over the entire mound. Finished sideslopes to be 3:1 or flatter. Grass cover should be established as soon as possible over the mound area to reduce erosion and aid in evaporation. THE MOST IMPORTANT STEP IN CONSTRUCTING A MOUND IS PREPARING THE NATURAL SOII, SURFACE BY DISC -PLOWING OR CHOPPING WITH A BACKHOE TO A DEPTH OF ABOUT 12". When sand is pushed or dropped onto this loosened raw top- soil (DON'T drive on it), an interface is formed which will allow percolation to occur from the sand into the topsoil. SEE SKETCH ON BACK OF THIS SHEET. DISTRIBUTION The mound must use pressure distribution and requires a pump from the septic tanks. Distribution must be 1Y' PVC or plastic with 4" holes (turned down) every 36". Pumping from a 2" manifold, distribution system should be 3 lengths of pipe spaced )�O" on center capped at the ends. running the length of the rock bed (see --ketch). No drop boxes or distribution boxes are used. 4" PIPE WITH GRAVITY DISTRIB- UTION IS NOT ACCEPTABLE IN A MOUND SYSTEM. PUMPING Pump should go in a 3rd tank or in a baffled chamber of 2nd tank. The idea is to retain the 2nd tank's capacity for solids retention. An alarm device and reserve capacity equal to one days sewage flow (300 gal. recommended min.) are required. ?"ICAL 'MOM' 6ZMG! T1REA11419IfT 6Y67T?1 LAYOUT 4 INCHES STRAW OR AIARSH SANDY 104M SOIL 6-1?" elwe HAY AND LAYER OF REO T ROSIN PAPER --� PERFORATED LATERAL GRASS COVER 6 INCHES 12-2l," SAND) FILL TOPSOIL MAxIMUM SLOPE 3 TO OPS IL��-- PLOWED ORROCK SURFACE 9" BELOY PIPS, 2" OVERDISKED CROSS SECTION A -A tt —IPF FROM PUMPING CHAMBER _ ROCK BED - _ ? RR Heron - 10'a 40, r. 4 PR Rnmp - 1 n I x 50, 5 OR Home 10,x 65, Pyr SAND FHL L SROVLD PERFORATED ' I i . N. xtT10' ^ -. FROM If LATERALS—�, V Hel-i �� ' ROCA BFZ 0?1 ALL SIDES. _.evnry fir.. .BSO AREA J s� TO 2 /j INCHESf -j r CLEAN ROCK I A 12" DEEP 1 { ( 6. ID `A ,►.�20_� -- IN�g _ N MES -_y SAND 0 3AND MAX 10 'n I VO k R[I' jn'—� t't'I R SAwl' PLAN VIEW QUESTIONS ? CALL THE ;'I?PTIC :.Y;;TEM INSPFCTOR AT N73-7357. EXl-l; L • TO: Jeanne A. Mabusth, Zc)niny Administrator FROM: Elichael P. Gaffron, Septic System Inspector DATE: November 6, 1981 SUBJECT: #654 Dicon, Willow Drive South - Subdivision I have reviewed the sub -fitted report for the above referenced proposed subdivision, and wish to make the following comments: The report by Borq indicates high -water -table soils throughout the 6 lots tested. Lot 1 - Slopes of 8%, lOc. Percolation rates at a depth of 25" - 31" averaged 10 mpi in the primary site and 23 mpi for the alternate site. Both sites are acceptable for standard mound systems. Lot 2 - Slopes rf 4-6% in areas tested. Percolation rates averaged 25 mpi in the primary site and 13 mpi in the alternate site. Both sites are}""-"'A-mnund systems. Lot 3 - Slopes of 5% - 6$ in areas tested. Average percolation rates averaged 27 mpi for the primary site, and 34 mpi in the alternate site. Both sites are acceptable for standard mound systems Lot 4 - Slopes of 3-4% in areas tested. Percolation rates averaged 41 mpi in primary site and 20 mpi in the alternate site. Both sites are acceptable for standard mount'. systems. Lot 11 - Slopes of 8-10% in areas tested percolation rates averaged 40 mpi in the primary site and 31 mpi at the alternate site. NOTE: CARE MUST BE TAKEN TO PLACE THE MOUND ON A SLOPE OF 6% OR LESS ON THIS LOT. Lot 10 - Slopes average 6%. Percolation rates averaged 48 mpi on the primiry site and 87 mpi on the alternate site- General C%tranents: Percolation testing was done at a range of depths frim 13" to 31". No real correlation appears to exist between depth of testing and percolation rates. The soil borings reflect a seasonably saturated zone beginning at a a range of depths from 1.2 ft to 2.5 ft. Actual current perched water tables were found on some sitesdepth of 3.5 ft. or greater. Based on the above data, the site evaluations recommendation for all mound systems is appropriate. I confirmed the soil boring report with a boring of my own. Two additional comments are necessary: 1 - Enough sand should be placed above the surface soil to maintain a 3' separation between the shallowest mottled zone and the bottom of the rock bed in the mound. On some sites this will mean 2' of sand should be placed. 2 - In all cases, mound placement should be at the most level spot available in the natural topography in the area tested. I recommend approval of the subdivision, with the further stipulation that during read construction the drainfield sites remain totally undisturbed. i TO: Jeanne A. Mabusth, Zoning Administrator FROM: Michael P. Gaffron, Septic System Inspector DATE: June 14, 1982 SUBJECT: #654 Dicon, 155 Willow Drive South - Additional On -Site Testing I have reviewed the submitted soil and site evaluation for the two lots on the north side of t?a road in Phase 1. Testing indicates average pert rates varying from 1 to 48 mpi, with high water tables (saturateu zones) in all but the most northeasterly site. Mound systems are apnlicai'e for all these sites, although the northern site for Lot 1, could support a shallow trench system. I note that Lots 2, 3 _ d 4 in Block 2, have be -en realigned. By superimposing the previous testing over the new lot lines, it is apparent that 2 of the 6 perc tests originally done on Lot 4 are now on Lot 3. Technically, additional testing should be done within the boundaries of the revised Lot 4. --er, since the soils appear to be fairly consistent througho :!,e division, and since mounds will be used on all the lots, th- i:inor additional testing is not critical and may be waived until a house is proposed for the site. I will reiterate that mounds should be placed on the most level sites within the tested areas; and that prior to road construction, all drainfiela sites shc..ld be staked off to eliminate traffic or disturbance. Mr. RichArd Conr` 21350 Fxcllsior Boulevard Excelsior, ;finnesota 55331 Dear '1r. Conry: Junes 1, Bo 1Wyy MN 55391 lie have completed a site evaluation for on-site sewage treatment facilities on 6 lots located west of Willow Road in Orono, :•finnesota. A location map has been enclosed showing the location of the percolation tests, percolation data, location of soil borings and relative elevations of the surface at the location of the percolation tests. (For detailed contours please see topography prepared by Gary Gabriel). A lo -0 of the soil borirgs is also enclosed. The soil borings reflect a uniformly high water table throughout the area tested. Thi3 condition prohibits the installation of conventional soil absorption systems and shallow trench systems. The percolation rates encountered and the gentle slopes on this site would indicate that mound systems should be satisfactory on each of these lots. We recommend that the future homes be provided with sound systems of soil absorption. Please call if you have any questions. Thank you. Se 1 81991 Yours very truly,^ Carl W. 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