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Home My WebLink About1991-11-13 MPCA Septic System Design ReqNovember 13, 1991. Eiden Constructic-n 41C>0 Bi rk:shi re Lane Plymouth, MN 5544-;- RE: Septic system design and pert-c-lation tests for; Minnesota Pol 1 ut i can Contreld Agency State C'er t i f i --At i in #75e Lot 6 Block: 1 Painter's Wo--ds Orono We were retained by Mr. Eiden to provide criteria for the design and installation of an individual sanitary sewage treatment system, to handle the sewage flow generated by water -use appliances within a single family dwelling. Pr oc edure A t _ta1 of fr C4 " s o i l pe i-c c.l at ion tests were per f.-.r rued c-n November 11, 1991 _�t a representative areas to the south and west of the proposed dwelling. In addition, four (4! soil Iic,rings were drilled with a i.d. x 3 1/4" rt.d. Hard auger to liec4:: for the position of the gr'-'und water table and t._, identify the underlying soil types. L.D.-ation of tests and bor :_rigs are shown on the site plan. The percolation tc_ts were performed in accordar►ce with the previsions of "Minn-�•sota Pollution Control Ager:cy F:LtL* e5 and Standards Chapter 8.:." The percolation tests IICles were - drilled to a alternate rnound depth of 1' inches with a 5" i.d. x 6" o.d. auger. T-.n-, inches ,.f pea gravel ware placed in the -- bottom of each to prevent scoring. Water was then added to the test holes and replenish•-d as necessary, maintaining a 1 -i Lich head of water ever- the butt gym. After a period of saturation, each lic-le was r=-filled to a 6-inch h•_ad of wat•_r over the bottom, and the percolatic,n tests coriai�•nced. Eiden Nover-inber 13, 1991 Page 2 Percolation Test F't�-sults ------------------------ Results of percolation tests at holes P-1, P-2, P-3, and P-4 are shown as observed. Percolation rates in minutes per inch are indicated as shown below: P-1 hole P-2 hole 43 mpi 45 mpi Site Average - 44 mpi Soil Borings ------------ B-1 Black clay loam Brown clay Yellow clay Mottling at B-3 Black clay laom Brown clay Yellow clay Mottling at 23,1 P-3 hole P-4 hole 47 mpi 48 mpi Site f,verage - 48 mpi R-z 0 - last Black clay loam 0 - 18" 18" - 30" Brown _lay 18" - 30" 30" - 62" Yellow clay CO" - 62" Mottling at 28" E-4 0 - 12" Black clay loam 0 - list 1::" - 36" Brown clay list - 28" 36" - 62" Yellow clay 28" - 60" Mottling at 25" Design I •.quir•_rfier►ts November 13, 1991 Considering the sails data and minimum design rc_quire,i.ents of tfle Septic Sysl erf, Ordinance-p our proposal is follows: Construct a Hound Systerfo based on a water cIf 75," gallons per day, f•_ r 5 Bedr :,can; Type I. 750 gpd .63 sq. ft. pgpd = 620 sq. feet bed area -minimum design size Proposed Design Size 1{:- &.2 bed = 62_r1 sq. ft bed area. 2- lr:CK:1 gal. pre_.c. _Ast tanks, + 1- 11;100 gal. purnp tank:. Construc*'_.D►► F'rc-,_edur_ For A Sewage Treatrw_--nt MC-und Soil Surface Preparatir_n A 2, inch discharq�- pipe frorit the pump to middle of the niound area shall be insf=.11ed pri�:r to sail surface prE-peratiotl. The trench excavat:•_d to in=_hall the discharge pi.p� shall be carefully back:fil!t,d and cofnpacted to prevent sepaye of effluent. The total area selected for the Mound, including that under the dikes, shall be rClughened in order to thoroughly break up any existing sod layers and to provide a suitable transition zone between the original sail and tF►,�- sand layer of the mound. The area shall be roughened only when the moisture content of the soil 8 inches below the surfac=_ is drier than the plastic limit. 'rile plastic lirfiit is the soil moisture content below which the soil may be manipulated for purposes of installing a soil treatment system, and above which manipulatic�ti will cause compaction and puddling. Surface preparation or scarification will be performed with a back -hoe bucket. There shall be no dead furrow in the r(IOund construction area. Mound constructi. ,t) shall proceed immediately after surface preparation is cote-opleted. Every effort should be taken to prevent rain from falling on the prepared soil 1 Surface. ConstruCtiOn Materials & Distribution of Effluent ------------------------------------------------- A clean washed sand laver shall be placed where the filter (rock bed) material. is to b•_ located. This sand layer must be at least 12- i n,_ hes deep and should be deep ens ugh to level area for mound. A crawler tractor with a 'blade or bucket shall be a=ad to roiove_ the sand into place. At least • 6 inches of sand shall be kept under the tracks t . rninirflize coriipact ion of the s._ ar i f i ed layer. The sand 1 ay.-r upon which the filter material i_ placed shall be level frorf, side to side and end tc. end. Only -=lean sand is to be, used. Eiders Construction NovenJ)--r-r 1�339 199 1 A depth of at least 9 inch -s of _lean rock: 1 1/4 irn_h diameter to 2 1/ irlches in diameter, shall be placed on the sand layer prier i,,-. installing the distributic-rl pipe. Pressure Distribul-i,,n Effluerltrshall be distributed over the filter rr-aterial by a 1 1/2 inch diameter p<_-rforated pipe under pressures. Perforation holes shall. be 1/4 inch in diari-ter drilled in a straight line along the length Of the pipe-. Holes spacing shall be 36 inches. Holes Shall bs drilled straight into the pipe and not at an angl:a. A sharp drill shall be used and any burrs in the inside or outside of the pipe shall be removed. The per f,-Drated pipe laterals shall b • installed level with the per foration== downward. The perforated pips, shall be connected to a 2 inch diameter manifold pipe and _hall have their endue ._app•_d. The laterals shall be spaced no further than 4r;- in-_hes On center and no further than inches from the ed��- of the filter material. Tile manifold pipe =hall be -:onnected to Vie supply pipe from the pump. The ritani fold shall be slope:i toward the pump for complete drain bacl: cif effluent. Pump and Col1ectic-ii Tan4:: A pump shall lbe-u =d to deliver effluent t-_j the resound. The pump shall be case: iron or bronze fitted with stainless steel screws or cc-nstructed of ether sound, durabl.•: and corr,:Osiorl-resistant materials. Location Of pufiip tank: and septic tank: can b- Optional due to tile- use of a pressurized mound. An alarm device shall be installed to warn of pump failure. The dosing chamber will be sized for a aiiniinurn of 2 days of restricted use du•_ to anic-unt of daily use. Purnp Discharge The pump discharge, capacity is based on the perforation spacing and perforation diartieter. This system has individual lateral lengths Of 61::- feet; laterals will be 1 1/2 inch plastic pipe with 1/4 inch perforations spaced 36-inches apart. This size will require 7 GPM per 100 square fret of bed area. A 45 GPM rninimurn pump discharge capacity is required. The pump discharge head shall be at least 5 feet greate-r than the heat: required to overconie the pipe friction loss and the elevation difference between the pump and the perforated laterals of the pressure distribution systt-rn, which is miniriiurn of (see purnp sheet) 15- foot head. Eiden Constructic,r, Noveri ),:?r 13 , 1991 The quantity of of fluent dr- livered eaCh puri1p cy._le should be at least 140 gallc-ris, but more than gallona per cy.=1e. The amount of efflt-,•-nt pump--d per cycle depends c-n the surface, area of tli•.• pumpinr, tank: and the setting of the purnp start and stop. A relatively large pumping tan1: surface area is needed with a sriiall puriip out depth. There are several pumping situations that ._an be used with this on -site sewaq� treatment system- These situations should be in cone-urrence with the City Ordinance- and the contractor installing the system. Inspection Pipe --------------- A vertical inspeci-ion pipe at least 1 1/2 inches in diameter to the bottom shall be installed in the rock: layi_r- of tfle mound. The inspection pipe shall be located at an end opposite from where the sewage tank effluent enters the rock: layer. The inspection piper shall have 3/8 inch, cw larger, perforations spaced vertically no more than sir, inches apart. At least two p--rforations shall be located in the rock layer. The inspection pipe shall extend t-D the bottom of the rock layer with an elbow beneath it and shall be capped flush with or above the finished grade. Eiden Constructiot) NJoveriiber 13', 1991 MAINTENANCE Pumping of Septic_ Tanks. The owner- of any individual sewage treo.Fment System Should properly _lean the septic tank: or tanks at least once every two (2 ) years c it sooner if necessary in order to prevent the sludge from reaching any pain. closer than 12" from the bottcxti of the outlet baffle or i.;1ie scum fe rii reaching a point closer than 3-inches above thy bottom ---,f the outlet baffle. H,:wever, due to the use of this; _iysteni ' he tanks shall tie purnped at least 1 time a year to prevent any solids from entering pump tank:.. Dvainage and final. Landscaping ------------------------------ All surface water-, must be kept away from the mound area. is drainage plan shc-uld be corllpleted to ensur_• that surface run-off from roof and parking surfaces are drained away from the system. To help the functi._ning of the riiound system, it r,iust be sodded. Shrubbery can be planted around the ba=,- but NOT on top of the rioOLUO_j. If sod is not feesable the m sund area shall be covered )i. th hay and seeded as to prev!_nt errosion. A water meter must- be installed to measure all water entering this syst�:ris. NOTE: If a chlorinat,=d Hot tub is installed in the house this -must be daylighted and not pluriibed into the septic- system. Chlorine Does krill bacteria in the septi tanks. --------------------------------------------------------- Eiden Const'ructic_11 General N ; vrriib r 1 33, 1331 Th•= contents of tlii.s site -valuation and design report are to be applied to the property listed --reprints f.--,r other application only with the permissicm of Pandy -_r Donald Schneewind. The sail have b-_en established at th-:- test hole locations i-xnly. There may be variations in soil stratigraphy betw-.-•gin and around the borings, and interpolation and �-.xtrapolation of the results is not warranted. All requirements ,F this dr:sign shall be- fcAlo-,.—d in order for the system to perform up to the designed ccapAbilities. References Horiie Sewage treatment University of Minnesota Agriculture Extension Service Pcger E. Machmi er Extension Engineer And Orcmo Septic System Ordinence and Minnesota Pollution Control Agency Pules and Standards Chapter 7oee') If you should hav- questions or need further infc-rrnation, you can contact staff at the City of Orono, or cc_ntact us at your convenience. c' •�cyr'ely Zza R & ,. Soils Consultants IIN 110. v 1. • O , ` \ `Rty �' � i• '' gENCNNAJeJ< �s11. 7V� ILo 111 /IQ, h.1,-V Gmty, Hinnrsotn 2� 1 --+9 a a t w o TE I UTILITY GWIN6,C �fCNCltt' /10 I//100 Proposed Top of Block / —moo ard. E1 ' �4 A e01vEor/r_: Rid_ Iso_.1_ ��• n r. Proposed Garage Ploor Proposed Lo"3t Floor 9d)0.s g10..3 Proposed krodes "Ject to results of soil test. \ � I • Lot 6, Kock �1.TiN3 YOOOS � N1e.11 *: Usln�111e.�I w.«+«I�Awrll.11� r.raw k M IV.I. � In.• ._� •+w.wl ..w•w.�...1.Nwn rJ ..I•w.w w1 Mw a a