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HomeMy WebLinkAbout1993-12-20 Septic System Design Reportr , 6 .. �O TESTING, INC. Steven B. Schirmers — MPCA Cert. No. G.27 ' 951 Katydid Lane NE • St. Michael, MN 55376 • (61 21 497 3566 IVA `be .11943 Dickey site Lot 1, Block 2 Orono, Henn. Co., MN This On -Site Sewage Treatment System is Designed for a Type 1, five bedroom home in accordance with the Minnesota Pollution Control Agency Chapter 7080 and local ordinances. The soils on this site are SCS soils mapped - LrB - Lester loam. A seasonally high water table was located at 14" to 22", (mottled soil). Due to the seasonally high water table, a Pressurized Mound System will need to be installed. The bottom of the rock bed must be located at least 3' above the seasonally high water table. The soils at a death of 12" have a percolation rate averaging 5.5 min/inch. A pumping chamber will need to be installed to lift the effluent to the treatment area. The manifold and supply line pipe must have back drainage to the pumping chamber. The distribution pipes shall have their ends capped. Be sure the rock and sand fill material are clean. The sod layer below the entire mounded area must be turned over, just break up the sod, be sure not to over work. The power supply and switches must be located outside the manhole and pumping chamber in a weather proof enclosure. A warning device must be installed with a light and sound device, this is in case of a pump failure. Mercury floats are a good method. All neighboring wells are located greater than 100' away from the proposed treatment area. CONT'D Dickey site lot 1, Blk.2 Orono (2) Keep all heavy equipment off of the proposed treatment area before and after construction. The treatment area should be marked off before construction. This Design is not valid & the System will need to be relocated if failure to protect the areas proposed for On -Site Sewage Treatment occurs. With proper installation and maintenance, this system should have no problem in treating septic effluent effectively. Nothing other than gray water, (laundry, showers, etc.) human waste & toilet tissue should be disposed of into the septic tanks. Garbage disposals are not recommended. Smaller amounts of laundry soaps, dish soaps, cleaning agents, etc. are better for the system. Antibacterial soaps & chlorine agents may kill the bacteria needed to treat septic effluent properly. Additives are not recommended, they may cause harmful damage to your system. Recommend to pump & clean your tanks by a certified pumper every year if you have 1 tank & every 2 years if you have 2 tanks to insure proper maintenance. �� Z en B. Schirmers CSS SBS/ds og#frWcrt'cv-<ow 0 gv 37' b 1f 7-4 i 71 `I J t,4 :p A rtv, oil OU�IEEV SUII DING t� " F r J., T"ILyi' y INSPTOR 5",4 C -1 Y p FFR%IIT NO. t t j Jp D.�7E 111999 PRUb CD AS SU3F�iiMr) PRr.wm wim CCRRrC'f10NS AS NUM) t u , T PYf'Rt)VFD -- C(?RKECT & ftEcJUE'i.i1T 1 fJy� mmer.ts are hu yet IK o..�rnuor. A': �etrk Mal be d.Ind I 'r 4 0r In :ull nriobnce wltt+ all al�{Jlicw?le tutbYr>d d aurtmg node �' �v� ��O.JS Guirnr entc mdretmp, ieenu "ot je1PKaov ncicd n thi'- rev's- KIIEP THIS PIAN SET uN SiTE AT ALL TWJf Ih •app) 7� 'p � o xo � � �• � .. � h J T ? co C m n a r I qp It, n n r n . C 0 o N () Q, Ir' m to O n o p rn a'D 3 r� rr7 U D� Q� O x J Y, N N O C ti N m 1 3 ED - N o Q � n F Y, N N r'l O 3 1 3 ED - N o Q � n F atm TIS O O O 3 33 ~ r V, �.O n cm O �D N N N o D Y 3 1 5. 3 0 !: xr0 r r—� !-�- I`rjq M_I�_I r o' n p 00 0 R 33 3 3 11 �I l 8 ct ; Y I► - n ) i ro Y, Q O �a Ln O o n n - s atm ~ 2 2S1 to �D J D A CL U, 3 0 !: xr0 r r—� !-�- G) o' 0 Q O �a Ln O M F �z i o MOUND DESIGN WORKSHEET (For Flows up to 1200 gpd) A. FLOW Estimated -0 �5-'O gpd (see pages D-7 or I-3, 4, 5) or measured --- gpd x 1.5 = B. SEPTIC TANK LIQUID VOLUMES 4 J-/oo a gallons (seepages C-3 or C-5) C. SOILS (refer to site evaluation) 1,0-1 0,V C- 1. Depth to restricting layer = a o inches I 2. Depth of percolation tests = ! a inches 3. Percolation rate S • 5 mpi 4. Land slope 3 D. ROCK LAYER DIMENSIONS 1. Multiply flow rate by 0.83 to obtain required area of rock layer. Daily Flow x 0.83 = J gpd x 0.83 sq. ft./gpd = �� sq. ft. -t 10 -,o 2. Select width of rock layer (10 feet or less) = 1 ft. 3. Length of rock layer = Area + Width = G_ ieisq.ft.+ /o ft. =Lu ft. E. ROCK VOLUME 1. Multiply rock area by rock depth to get cubic feet of rock; 4,, t sq. ft. x/,os ft. = ecu. ft. 2. Divide cu. ft. by 27 cu. ft./cu. yd. to get cubic yards; rL-�, cu. ft. + 27 = z,) cu. yd. 3. Multiply cubic yards by 1.4 to get weight of rock in tons; D n cu. yd. x 1.4 ton/cu. yd. = a5!� tons. F. ADSORPTION WIDTH �LLA " L-04-1 1. Percolation rate in top 12 inches of soil is mpi 2. Select allowable soil loading rate from table on page E-; . q,5' gpd/ft" 3. Calculate adsorption width ratio by dividing rock layer loading rate of 1.20 gpd/fP by allowable soil loading rate; 1.20 gpd/ftp+ ,,t < gpd /ft2= ;)- L,? Check this value on page E-16. 4. Multiply adsorption width ratio by rock layer width to get required adsorption width; ,�.Lr7 X is ft=.0 t.,2ft Eaimaaed Se -age Flus in Gallunl pa day (Spd) an bex Uftof Abmgd -Wt% 0ft* Law WIaM F~ tMa0.1 • GOana Swd - of TyPt I I Ty fc 11 Type III I Type neaarr.t Fre Sand •• 0.60 2.00 IV 2 300 221 160 Loam 3 450 300 216 0.50 4 600 371 216 2A7 5 710 410 29a Steno than 6 900 325 332 7 1050 600 370 1200 673 406 Snti T..4 C.V+ W" i. a.%- %ombrof M.a•. Lq..d L.q..Jc•p�y.M a.Are.w. Cq•cry arlb•M "Paw 2w 1e.. 730 1123 2 r 4 1000 Iwo 4 r 6 1310 2210 7, 6 -1 » 30M a.v 1 -- Rock Bed II I• J•I J•J•J•I•I•I•J•J•J ZZ�.�`�. I•I•I•I•I•J•J • • ??__f�� 1•x•1,•\•ti•1.• til Sett. •I ♦.3••I� J•J•J•J•J•I.J •I•I• •J •J• •J•I•J•: •: •J•J F--- I.en6th Absorption VAdth Sizing Table fon elation w in Mimleat 1fM(MPI) Solt Teatan Gallons pet day per Pere fm Uftof Abmgd -Wt% 0ft* Law WIaM F~ tMa0.1 • GOana Swd - - 0.I e S Srd 1.20 1= 0.1 io3 a• Fre Sand •• 0.60 2.00 6,013 Sandy Lana 0.79 137 16 In 30 Loam 0.60 2.00 311045 SiM Lar" 0.50 7.40 46 b 601.0am 0.45 2A7 4010120 ay 0.24 5A0 Steno than Clay - -- 12D'-. X ope is 3% or more, subtract rock layer width from on width to obtain minimum downslope dike toe for absorption: L,7 ft - _LC) ft = feet 2. Calculate minimum mound size based on geometery: a. Determine depth of clean sand fill at upslope edge of rock layer: Separation /.:5' feet b. Multiply rock layer width by landslope to determine drop in elevation; Slopc Difference ,/0 x ' %+100= •3 feet c. Add depth of clean sand depth of clean sand for separation at upslope edge (2a) to depth of rock layer to rock depth and the depth of cover to find the total mound height at upslope edge of rock layer; /. :3 ft + 1 ft + 1 ft = 3.'3 feet d. Enter table on page bottom with landslope and upslope dike ratio. Select dike multiplier of 3 .-<q e. Multiply dike multiplier by upslope mound height to get upslope dike width: 3_ x 3.5'? = 1-a feet f. Add the depth of slope difference (2b) to the upslope height to get the downslope height 3, z + = 3, C, _feet g. Enter table on page bottom with landslope and downslope dike ratio. t Select dike multiplier of 4. Sy h. Multiply dike multiplier by downslope mound height to get downslope dike width: 3• c, x q.sv = I G feet i. Compare the values of step G.1 and Step G.2.h. Select the greater of the two values as the downslope dike width; �'I feet ..........•• j. Total mound width is the sum of upslope dike Kocktk-d WWhk%_4a'' .'h SWI 01—JZ width plus rock laver Nvidth plus d ownsln^_ dike width; I,�Kock + /_ ft + ft = feet �,,I,.aki►►a_ 1X. k. Total mound length is the sum of upslope ; dike width plus rock later length plus upslope dike width; lam- ft+ U- 'e, ft, )7 —ft= _ r -_ fact t,..�. •��. _/ 3:1 ll wnslopc 5:1 LI 7:1 3.1 4.1 UPSIOPC 5:1 4:1 7:1 it 16 43npt 0 3A 40 SO 4.0 7.0 30 40 S.0 40 7.0 t0 1 301 417 434 7M 711 1.3 474 544 454 7AI 3 3.11 3� e 536 S. 417 7.12_. 1.14 7 0 7 ?.7. 4.54 4.35 534 SM 414 S 4.f3 4 45 l 330 34 4.St !:4 S: _ 67° 7!1 i.K. 41' 4L1 5 406 5.0. 4:" t5. '•: 4ni c._ S1: S71 4 3K SM 714 934 1:07 75t ?J 3 i 44; 493 341 7 3B3 SSi 7.N 1034 1373 7Y ).11 370 4 2 470 S33 1 3.1s INi3J 1154 1511 143 301 351 4 U 441 4M 1 4l1 43S t.tv 1]04 1117 334 7.9. 345 310 430 ILS 10 4]9 40 100 1s0o 3333 711 70 733 375 4.t7 411 11 4.0 7.14 11.11 t745 3043 714 774 323 341 3.9s 434 11 <N :.N 13-0 7:43 4375 771 7.:0 317 3to 390 401 PUMP SELECnON PROCEDURE A. Determine pump capacity: C' Gravity Distribution 1. Minimum suggested is 600 gallons per hour (10 gpm) to stay ahead of water use rate. 2. Maximum suggested for delivery to a drop box of a home system is 2,700 gallons per hour (45 gpm) to prevent build-up of pressure in drop box. Pressure Distribution 3. a. Select number of perforated laterals .? b. Select perforation spacing : i ft. c. Subtra 2 ft. from the rock layer length. 11� - 2 ft • � [t. d. Determine the number of spaces between perforations. Length pert. spacing . /, L., ft + ft. _ 2 -7,_ spaces e. _�'i!= spaces + 1 �_ perforations/lateral f. Multiply perforations per lateral by number of laterals to get total number of perforations. 1=. x A �_ &-j, perforations. g' a x Q��= &ZBPm SELEIL I ED PUMP CAPAQTY 3� gpm V. Determine head requirements: 1. Elevation difference between pump and point of discharge. ):Z_ feet 2. If pumping to a pressure distribution system, add five feet for pressure required at manifold �. feet 3. Friction loss a. Enter friction loss table with gpm and pipe diameter. Read friction loss in feet per 100 feet from table. F.L a :i . L ft./100 ft of pipe b. Determine total pipe length from pump to discharge point. Add 25 percent to pipe length foi fitting loss, or use a fitting loss chart. Equivalent pipe length - 1.25 times pipe length = 11 �_ x1.25- Z) 1C/ feet c. Calculate total friction loss by multiplying friction loss in ft/100 ft by equivalent pipe length. Total friction loss = N . L. x t ✓ +100 = _ ( feet 4. Total head required is the sum of elevation difference, special head requirements, and total friction loss. + S, + L� (1) (u (30 TOTAL HEAD _-) "_ feet C Pump selection 1. A pump must be selected to deliver at least Z_ gpm (Step A) with at least �_ feet of total head (Step B). EM PERFORATION OF A PERFORATED LATERAL «� c... TyW .• ; lww .t wMar. rWk I. I. M7rw NM IMr.w�Mf • w Ir,e tM Ir N CAP _ LAWN .4�. ralraivalwue N i - Greer tow L"W W4. of La"M carr ... ta..ul.e TABLE OF PERFORA noN DtSCHARCEs IN CPM Head Paloration dlraudw 0ndwl 10 7/0 148 lam 036 0.74 is 069 0.90 26b OJO 1 X01 23 029 1.17 30 0.98 120 4.0 1.13 1A7 510 126 165 au" 1.0 foot of herd for nm1&ntW 2ysleena. blhe 2.0 !«t of had far o1l+a aalAbtLF�+rn4 Pipe LAmph Point of DischarS )elevation Difrem-me Pump p n � F -18b 1.5 inch 2.0 inch 3.0 inch BPM Rlaimkup.IOonerr4+ 10 0.69 0.20 12 0.96 0.28 14 1.28 0.38 16 1.63 0.48 18 2.03 0.6u 20 2.47 0.73 0.11 25 3.73 1.11 0.16 30 5.23 1.55 0.23 35 7.90 2.06 C.30 40 11.07 2.64 0.39 45 14.73 3.26 0.48 so 3.99 0.58 55 4.76 0.70 60 5.60 0.82 _ . J 1 . ion or Project Dickey site, Lot 1, Block 2, Orono rings made by G -P 7_esting, Inc. Steve Schirmers Date 11-3-93 Classifiction Sy3tem: AASHO USDA -SCS X Unified Other Auger used (chp-', two) : Hand X or Power Flight , or Bucket X Depth, Borg. Depth, Boring number 2 in in feet Surface elevation feet Surface elevation 997'9 - -- - — 0 - -- - -- - 2 - 3 - CM 5 - 6 - 7 - M Topsoil dark brown loam 0 - 1' Brown clay loam 1' - 1'10"-MOTTLEDI'10 Rusty olive brown clay loam 1'10" - 2'4" Rusty olive brown loam 2'4" - 3' Rusty olive gray loam 3' - 4'8" Rusty olive gray silty loa 4'8" - 5' End of boring at 5' feet. standing _able: present at feet of depth, hours after boring. Not present in hole X mottled soil: Observed at 111011 feet of depth. Not present in hole Comments: 1 2 - 3 - <C 5 - 6 - 7 - 8 - Topsoil dark brown 0 - 10" loam Brown clay loam 10" - 1'8" -MOTTLED 1'8" Rusty olive brown clay loam 118" - 2110" Rusty olive brown loam 2'10" - 5' End of boring at 5' feet. Standing present at feet of depth, fours after boring. Not present in hole X Mottled so--.': Observed at 1'8" feet c depth. Not present in hole Comments: ation or Project Dickey site, Lot 1, Block 2, Orono orings made by S -p testing, Inc. Steve Schirmers Date 11-3-93 Classifiction Syztem: AASHU ; USDA -SCS X Unified Other Auger used (check two): Hand X or Power Flight or Bucket X Depth, Boring number 3 Depth, Boring number 4 in in feet Surface elevation feet Surface elevation_ 995,2 2 - 3 - 4 - 5 - 6 - 7 - 8 - Topsoil dark brown loam 11cc0 - 1'4" C' � riot, �PP4" - 1'8" -MOTTLED 1 Rusty 1,8"- 2'2" ftiO YESmn Rusty olive gray clay loam 2'2" -3,8" Rusty gray silty clay loa 3'8" - 4'A" Rusty olive g' y loam 44441 - 5 End of k:oring at 5' feet. Stan i .:at_r table. present at— 4'1" feet of :!epth, 16-1/2 hours after borirg. Not ;.resent in hole Mottled soil: Observed �at 1'8" feet of depth. Not prez�_nt in hole Comments: r8 Topsoil dark brown loam 1 0 - 1'2" -MOTT Rusty , , �., _ 1 _1 /-),o 2 - Rusty gray brown clay loam 1-1/2' - 2'10" 3 - Gm 5 - M 7 - 8 - Rusty gray clay loam '10" - 5' End of boring at 5' feet. Standing water table: present at 2'11" feet of depth, 18-1/2 hours after boring. Not prrsent i:. hole Mottled soil: Observed at 1'2" feet of depth. Not present in hole Comments: 1'2 gi$, X n or Project Dic-key citP_,made by;P;ting, Inc. Steve Schirmers Date 11-3-93cticn System: AASFIU ; USDA -SCS X Unified Other Auger used icheck tt.,o) : Ilanc:_ K or Pcl-jer Flightor Bucket X Depth, I Boring number 5 Depth, Boring number 6 in in feet Surface elevat.on 995.0 fSurface elevation 594.5 _ 2 -- 4 - 5 - 6 - 7 - 8 - Topsoil dark brown loam 0 - 1' 2" 1,Lvwl1 L:107 1Vd111 1'2" - 1'8" -MOTTLED 1'8 Rusty olive brown clay loa 1'8" - 214" 71usty214" - ?'8" o�jveay � �a Rusty olive gray loam - r, ' End of boring at 51 feet. Stand, n5 water table: preseni at 3'7' feel, ct 18-112 hours after borin.l. Not p esert. i, le Mott l .,d soil: Observed at1, 81, feet of depth. Not present in hot= Comments: 1 - 2 - 3 - 4 - 5 - 6 - 7 - Topsoil dark b,,awn loam 0 - 1'2" -MOTTLED 1120 Rusty 1' 2" •- 1-1/2'9Mngf8Xm Rusty olive brown clay lr- -i 1-1/2' - 2'2" Rusty olive gray clay loam 2'2" - 314" Rusty olive gray loam 3'4" 5' I I � I I. End of boring at feet. Standing w� ter tab1_ : present at 3'5"- ' et of rl<-pth, l 18-1/2 hours al er poring. I Not present in hole - Mott, d ole - Mott -.d soil Observed at 1 '" - feet of dev i. Pot present i ; Com -encs: RT 00 PERCOLATION TEST DATA SHEET a.m.' latirt; tc�t readim�� m.,.lt h� S—P T ati nq, Tnc on 1 1 —4-93 :;:ming ar 8:02 _ h.n, Test hole location Lotl , Blk . 2 , Dickey site Hole number 1 Date hole ��ac prepared 11-3-93 Depth oI hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole: r!nth. inches Soil texture 0 - 12" Topsoil dark brown loam Method of scratching sides all Knif e 2 ith of gravel in bottom of hole—. 11-3-93 1:30pm 12 and hour of initial water filling . Denth of initia! water filling inches above hole bottom Aethod uwd to maintain at least 12 inches of water depth in hole for at least 4 hours Automatic siphon . Maximum •.% iter depth above hole bottom during test 6 inches Time ime i ir<,•rr. , i minutes Measurement. inches Drop in eater leer. inches Percolation rate. arks minute< per inch 7:50 prefill 6 8;02 8:17 " 3-11/16 4.1 15 min it 8:43 1 8:58 I 3-7/16 4.4 go _ r. 3- 3/ 8 4. 5 8.59 9:14 --- _ l Percolation rate - 4 ' 3 _ Butes per inch. CERT -t00627 PERCOLATION TEST DATA SHEET 8:03 a.m. Percolation tt>t readutL, made h\ S—P Testing. InC . on 11-4-7j starting at p.m. ' •Jen , Tcst hole location Lotl , Blk . 2, Dickey S].te}iole number 2 —. Date hole was prepared 11-3-93 Depth of hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole: Depth. inches Soil texture 0 - 10" Topsoil dark brown loam 10" - 12" Brown clay loam Method of scratching sidewall Knife Depth of gravel in bottom of hole 2 inches 11-3-93 1:30pm 12 Date and hour of initial water filling Depth of initial %-ater filling inches above hole bottom Method used to maintain at least 12 inches of water depth in hole for at least 4 hours Automatic Siphon 6 Maximum %%ater depth above hole bottom during test inches ,'ime Time interval. minutes Measurement. inches Drop in water level. inches Percolation rate. minutes per inch Remarks 7:50 prefill 6 8:03 8:18 of 1 4-1/4 3.5 15 min P •. 12 8:57 is 4 3.9 " 9:00 9:15 " 3-7/8 3.9 " Percolation rate = 3.7 _mtnut-s per inch. T.r00627 PERCOLATION TEST DATA SHEET a.m., Percolation test reading. made h•. S—P Testing. Inc. 011 11-4-93 starting at8: 04 Test hole location Lotl , B 1 k . 2 , Dickey s i to Hole number 3 _Date hole was prepared 11-3-93 Depth of hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole: Depth. inches Soil texture 0 — 12" Topsoil dark brown loam Method of scratching sidewall Knife Depth of gravel in bottom of hole 2 inches Date and hour of initial water filling 11-3-93 Dep3h0� Initial water fillin" 12 inches above hole bottom Method used to maintain at least 12 inches of water depth in hole for at least 4 hours Au temat : e si phen , Maximum water depth above hole bottom during test 6 inches ime Time ( inter al. Measurement. minutes i inches Drop in %% ater level. inches Percolation rate. minutes per inch Remarks 7:50 prefi11 6 8:04 8:19 3-3/16 I 4.7 15 min 8:41 8:56 " 3-1/16 4.9 orof 9:01 9:16 I 3 f 5.0 ofIN I I � _ I � I � I I � � i � I Percolation rate 4.9 _minutes per inch. RT.#00627 PERCOLATION TEST DATA SHEET a.m. Percolation test readines made h\ S—A TPctt i ng, Inc- _ c,n 11-4-9 3 startine at 8:05 p.m. Test hole location Lot 1 , B 1 k . 2 , Dickey site Hole number 4 Date hole %\ as prepared 11-3-93 Depth of hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole - Depth, inches Soil texture 0 — 12" Topsoil dark brown loam Method of scratching sidewall Knife Depth of gravel in bottom of hole 2 incises 11-3-93 1:30pm 12 Date and hour of initial water filling __. Depth of i,iitial %%ater filling inches above hole bottom Method used to maintain at least 12 inches of water depth in hole for at least 4 hours Automatic siphon 6 !Maximum water depth above hole bottom during test inches ime Time interval. minutes Measurement. inches Drop in water level. inches Percolation rate. minutes per inch Remarks 7:50 prefill 6 8:05 8:20 It3-1/2 4.3 _ 15 min 8:40 8:55 of3-5/16 4.5 " 9:02 9:17 3-1/4 4.6 " Percolation rate = 4 • 5 minutes per in. --h. T.p00627 , PERCOLATION TEST DATA SHEET a.m. Percolation test readings made h% S -P Tp -,ting, Inc. on 11-4-93 stanin,_ 8:06 p.m. Test holc location Lotl,Blk. 2 , Dickey site Hole number 5 Date hole vas prepared 11-3-93 Depth of hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole: Depth. inches Soil texture 0 - 12" Topsoil dark brown loam Method of scratching sidewall Knife Depth of gravel in bottom of hole 2 inches 11-3-93 1:30pm 12 Date and hour of initial water filling . Depth of initial water filling inches above hole bottom Method used to maintain at least 1' inches of water depth in hole for at least 4 hours Automatic Siphon 6 Maximum water depth abo%•e hole bottom during test inches ime i Time interval. � Measurement. minute: inches Drop in water level. inches Percolation rate. Remarks minutes per inch 7:50 prefiI1 ! 6 8:06 8:36 of2-5/8 5.7 30 min 8:39 9:09 go2-7/16 6.2 ' it 9:10 9:40 2-3/8 6.3 j I I � I Percolation rate = 6 . I_... _ ndtes per inch. T.100627 PERCOLATION TEST DATA SHEET • S -P Testing, Inc. 11-4-93 8:07 Percolation tort readings made b� on stamn;_ a� p. M. Test hole location Lotl , Blk . 2 ,Dickey Site Hole number 6 Date hole was preparertll-3-9 3 Depth of hole bottom 12 inches. Diameter of hole 6 inches Soil data from test hole: Depth, inches Soil texture Topsoil dark brown loam Method of scratching sidewall K n Lf a Depth of gravel in bottom of hole 2 inches 11-3-93 - i o 3�O�m.w12 Date and hour of initial water filling epi n i t ial ater filling inches above hole bottom Method used to maintain at least 12 inches of water depth in hole for at least 4 hours Automatic siphon Maximum eater depth above hole bottom during test 6 inches .: ime Time interval, minutes Measurement. inches Drop in eater level. inches Percolation rate, minutes per inch Remarks 7:50 prefil1 6 8:07 8:37 3-3/16 9. 30 min 8:38 9:08 9:11 9:41 Percolation rate = 9.4 minutes per inch.