1991-11-13 MPCA Septic System Design Req

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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.