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PROJECT:SGM NO.:DATE:PREPARED BY:Garfield County Dept" of Public HealthOWTS Checklist Design CalculationsDavis Res¡dence OWTS2021-319.001'10-May-2'lBrandyn Bair, PEDes¡gn €lrulations for the s¡zing of æptic system tank.1. Colorado Water Quality Control Commission (CWQCC) Regulation 43, Onsite Wastewater Treatment Systems Regulat¡on2. Garfield County Public Health Agency On-site Wastewater Treatment System Regulat¡ons1. Single family res¡dential design nows (gpd)2. Minimum sept¡c tank €pacity (gal)3. Minimum set-back distanæs (LF) for OWTS4. Septic tank design5. So¡l treatment area design6. Assuming design to €æive septic frcm the single family resid€nce.7. Assuming that the approx. invert out of septic will be 4" pipe at slope of 1/4" per foot, beginning -24" bdow FFPURPOSE:GIVENTASSUMPTIONS /KNOWNCONDITIONS:LEGEND:1. DESIGN FLOWS2. MINIMUM SEPTICreG¡ven value or condition'l.z5g loalløsl.5oo loallonsltank forthis ¡n order to ensure m¡n. 1-ft freeboard ât 48-hr detention time.cSeptic Tank Calculations
3. TREATMENT LEVELS4. SEPTIC TANKNo. tank æmpartmenb =Min" volume of fißt compartment =Min. distance from inlet to outlet invert =Min. distance from outlet invert to tank top =Min. l¡quid depth =Max. I¡quid depth =M¡n. liquid surface areâ =M¡n. distance from inlet(s) to outlet(s) =Min. detention time =5. SEPTIC TANK DESIGN CALCULATIONS12Check caÞac¡tv aoalnst min. detention t¡me and freeboard(1 ) Assume min. freeboard des¡red =(2) Min. volume to store for 48-hr detention time =Excess volume @ 48-hr detention =Fr€ebærd @ 48-hr detent¡on t¡me =Garfield County Dept. of Public HealthOWTS Checklisl Design Calculations(Reg 43.9.8.4.a)(Reg 43.9.8.4.a)(Reg 43.9.8.4.b)(Reg 43.9.8.4.e)(Reg 43.9.8.4.f)(Reg 43.9.8.4.f)(Reg 43.9.8.4.i)(Reg 43.9.B.4.i)(Reg.43.9.1.3)7.4E05 gal1frgal450 gal60.16 CF1 .'11 ll aonly consldeß freeboard in the ñßt two ûompartments; coßeryat¡velintnin¡nSFCF=¡n=1 /O_baa2353to.7529.411764711 0.13o.1329.4't176471 I1 1.76470588 1 0.051 1. /64/Uböðtu,u51U1014t2512N3NU I TtJ:1 Calulated assuming CBOD5 is approx. equal to 85% of BODs.2 Calculated dailv loadinq based on desiqn fow assumed for the s-bed house./50.o3'ï i¡0zþ45tj/r50g49491,256.:0/69.ti/161.521 U¿.9b.1/t#1t5-OO33.54I6,5t3.r715.00fzt6.51 20.581Total Liould Caoacitv INETNU I Ê¡t:1. Tank dlmensions taken from Valley Precast (1500-|-2CP-HH) 1,500 Gallon Mid-Seam -2CP w¡th H¡gh Head Pump.2. Net câpac¡ty for each compartment per Valley Pre€st cutsheet.Septic Tank Calculations