HomeMy WebLinkAboutOWTS Design ReportRECEMED
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May 25, 2021
Devon & Cmþ Spaulding
t0441 cR 3t I,
silt, co 8 t652
dspa ulding(@montainfamiþ,org
cspauldingl 9@ groil.com
RË:Dcsign Report-Onsite Wastelwter Trcaùnmt Sysæm (OWTS), Spaulding Residerce, 10441 CR 3l I,
Silt cO, AKA RecordRanch Subdivisim Exenptio¡ Lot 2, Gsrfield county, colorado
SËJob No. 3 I 094.01 Pûrcel No: 2401 2420027 5.
Dear Deron and Craig:
This letter report pree$s 1llÊ applicûble flndings in regard to the design and construclion ofa new {)nsite Wastewater
Trsl¡ncnt Systcnr (OWTS) rt th€ above refcrcnced Silc, in support ofyour OWTS ptrtnit af,plic¡tion to çsrfield
Counfy. The OwlS dsign is bascd m receDt sitc assGsmerl obwnatims by Sopris Enginccing of exirtingph)6iffi1
site fcatures, ænditios gmtæhnicâl soils ewluation with rcspect to the propmql 16idmtial usuge and applicable
regulatory dsign criteria in acco¡dancc with State and County OWTS Regülalions. Tlæ dcign ræotmcndntiom,
speeifications and coßtructiou delails are dcli¡lmted on the attachcd OWTS pumiVcoßkuction plaÌ tlut was
prcpared with GtS, LIDAR, Suvey Plat inlon¡alion md acrial mapping. The d*þ criterin and system sizlng
'rfonnalion ¡s summgrized belov,
Smnurv Exl$tltrs Svstem Condltlo¡s
'l'he subjæt propefiy is a dfveloped s¡ts curcrtly comisting ofout-bùildings, ut¡liti*, roads and landscaping. Thc
origiml single fanrily rcsidmcc wns dstroycd by lirc. T'he proposed rcplæment rmidmcswill bc cmstructcd in thc
same gcnenl læation ofthc original house foolprint- Thc OrilTS, as dewribcd iøe, will rçìace the original system
which is to be abando¡rcd. No records of tlrc prcvious lSÞS or rslalsl pemits wcn found in the County's recolds.
Summory Dmlsn C¡lteris
The new OWTS is designed for â ¡ eatmen't cflpac¡ty of450 gallons po day based on the dßìgn wnsteu,aîer flow lo
serve a 3-bedm¡n residerce in accordance with Table 6-2 values. Sect¡m 43.ó, 4.4. The nerv OWTS will rtílire a
minìrnurn 1,000 gallon twa-compsrtmst reinforced plastic sr?lic tâ¡k to bc installed within tl¡c lûw ürcâ wcst ofthc
propmed dwlling structure. It is ¡womded lhat ribbs! PVC r¡ms with fiber lids will be inslalled on the ñew
septic tank along with appropriatepipe comwtion to lhe¡sv tank utilizing the approprislc fitting adaptor rings for
tlB tûnk and risen Thc plflstic trnk nìanufacturer's plastic risr and lids mny be utiìized with canful installstiou of
selæt gavcl and soil backfill fice ofrccks. Thc nw 1,000 gollon 2-compârhnmt reinforced plastic sptic tmk will
bc itstalled wìth approprisle saû¡tãry tees, outlel elfluenl filts with riseru and lids ¡t the surfâce. A gravity whcdule-
40 or SDR-35 swér pipe sætion with hvo-way clano{t pill be inshl¡ed betwæn the lârk itrlet on 1lß $Bv¡ty servtr
line a¡d thc primry dwelling
A gravity schedÙIe4o or SDR-35 efiluffit pipe fro¡n the new scptic lank will be istalled to ihe f,ew soil lTcatm€nt unit
(STU) absrption field with cle¡mul to û distribution box at the head ofthe lteld t¡enches.
The STU s¡ll comist of lmching chombcr trmches that p]ùide 525 S.F. of totol absorytion arm. The septic tarìk
effluort rvill be gravity disclnrged through a new 4-inch schedule-4O or SDR-35, installed ût miilnüm 1.5% slopc, to
502 Main Streel . Suite A3 . Carbondale, C0 81623 . (970) 704-0311 . Fax (970) 704
031 3
$opnrs lilûrttttrto . tlG civil consullanls
spûu¡ding Residflce
ovfTs, 10441 c.R.3r r
SE Job No. 3 1094.01
MoY 2 5, 20? I
Page2
thc STU via û dis{r¡bution box. The emucnt will bc cqually disûibufed from ttr distribulion box lia 4" distribution
pìps conrccted to the hsd fld cåp ofeach of4 clmmbe¡ trmcher. Observalion ports with caps rvill be in$ålled on
each end cha¡ntlcr rutit. TlÉ dsign is in cmìpliance with the curmt County regulatiom with design calcülatiors
based on thc soil type, texlure and structurc with an apprcpriatc long term âcceptance üte (LTAR). The dsignerl
system rreets all requirLlC stbachi &ûd will be installed wi¡hi¡r lhe gmøal lmation irdimted on the plan. Thc exis{ing
rvell serving thc rsidmcÈ (PtrÌút No. t58487) is læoted over 100 fæl east oflhe proposed field arca. Our dcign is
oullincd below and dclintl1ted on the ottf,alæd C'l OWTS plan.
Deslen Fþw
Thc design flow is calcularcd ¡s folloH [or thc anlicipstcd future waste fìom oflheexisl¡t8 single fmily dwelling
The roplaccmmt OWTS is dsigned for a trartrent cap[city of450 gallom per day bôsed on thc dcsign wastçw¿ter
flow to str\,e a 3-bcdroom capacity rsidorce in accord¡nce with T¿ble 6-2 valuss, Sælion 43.6, 4.4. Regulation 43:
Minirnun population bascd on 2 poson pc bedroom fu thc fi¡st 3 bedrætro = 6 persons
Use . 75 g8l/pcßor/ddy. No PF
Max. I]e,sign llow (Qd)pllons/day - (# of people) x (avg fìow)gûl/peßm/day'
Dmien flow Qd = ó*75=450 gPd
Sepdc Tük Dêslqn
The septic ttnk cûpacity requirerl for a rninimum 48 hour rctenlion timc is calculûted as follows:
V = 450 g¡l/day * 2 = 900 gallors. Use a mhirnurn 1,000 gallon 2-cûnpârtment rs¡nføced plastic septic tank. The
trnk to be irofalled rvith riprs and access lids se! û ninimum 3 inches above linish grade surface.
$ub Surfacc Conditions ånd Testing
A subsurface soil invstigadon and site flssessment wa6 perfomed by Sopris Enginccring in on May 17 , ?021 ' The
soils in the propmed ficld envclope area wcrc mnrplcd and characterizcd by applimlion ofüc USDA visual/tactile
soil texture nìsthod annlpis fun samples irr two profile pits. The soils below 6 inchs of topsoil coroist of mcdiunr
døseslighrlymndysiltlømfsxturesoilwithslightlyblækytogmnul¡r$tructureloadçthofSfeet. Thesoil
profile contains less thsn 20¿ sc¿tlsred gravel o rwk contcill lo the 8-fcat dc?th bclov tltc surfacc gradc. No fræ
waltr was mcoutrtered iD the nit excawtiors, Seasoml high Groundlatr lwels are qpccted to be bslow l0 fæt fiom
the cxisling surfocc grûds on lhe relûlivcly flat tenain
Thç n¡tive soils sampled from ?.3 feet below the surf{ce, in the viriîity oftlìe pr(posed field, are charoctsizei as a
soil typc 2 comisting of sllt loam tqture wifh gmnulsr 6ûu{)turo. Tbis soil has an effmlivc ¡oading rûþ for
conventional soil trstnrent of0.6 GâyS,F/day for a levcl I mtrventional lreatnent syston The equivalent percolation
mteisas$ürnedtobe20-30minutsperirch. l'hesoilsa¡esuitablefcrashallowcmventionalshallowabsorption
field consising ofgravetless intiltr¿tion chamber units.
Treatment-Soll Trenlment Udt/ Absorpllon SYStem D6ign:
The rr!ìâtmmvübsorption ficld is designed bâsd on ut¡lizing the cffætive Long Tsrm Accef,tânce Rate (LTAR) for the
native soils and the rpplicatíon ofâppropriate lmding lactuc for a soìl trealme¡t unit systm utilizing gravity
distribution to grâvellss chamber trenchs. The nçw tÍeâlment system ond ûbsorption freld rvill mroist ofgravity
distribution ofseptic tank efTlus¡t r.ia ¿ distribution box to lìdividusl chambü trmchß t4th fteôtms¡t across the
native sil absorpf ive surface.
Spoulding Residmce
oìtr'Ts, 10441 c.R.3l I
SE JÕb No- 3 I û94-01
Møy25,7021
Pagc3
¡,ons Term Accentmco Rote (LTARI
Considcring the applicütion oflhe sla¡c regulûlion 43:
Ræeiving Wastemter Treatment Lcvel l; Soil type 2 loåding rstc fqr a silt loam i* (0.6 g¡l'/S.F lday).;
Lmdìng factors; (Table I 0¿, Crâvity ûpplictt¡on trenchs = I '0 ) and
(Table I 0-3, gmvcll*s chanbeË = 0.7)
A(si)=Od*t.t.t*t.t.t.' A=Arm;
LTAR LTÁR = 0.6 G¡l/S.F./day for silt loatn
Qd = flol (gallday) = 450 gttl
L.f .l=1.0 Gnvìry Distribution
L.F.2=0.7 Clra¡rbe's
A(sf) -450 gpdx 1.0 x 0.7 =525 S,F.
0.ó GaVS.F./day
Numbcr of Quick-4 lnfÌhator chambers 4'x3'xlZ"chambçs:
525 S.F. = 44 châñb€rst Use44 çhambeË
l2 S.F./Çhamber
Use 44 Quick4 lnfillr¿tor clumbss in 4 trenches 46' long by 3' wide with l I charlbcrs units pcr lrcnch plüs t\vo ctd
caps as deli¡ìslcd on the plan, The se¡tic tank eflluent rvill be grâvity distributed to lhe head of each cha¡nber row via
irdividufil distribiltiou pipes lrcm a dislribution box.
Coustruct¡on snd Isspstioß
Prjor lo construction of the ¡rermilted systcÛr, lhe engirer should be conlacted by the conlrsctor and omer well in
adYancc lo provide adequote timc to discuss thc system conponelrts with the contmc(or, an$wcr queslims, rcsolrt any
conflict issum ¡nd schedule ins¡ætion site visils based on mnst¡trctim progress. l\ preOWTS coNttuctiqn næting
isesseftiâlondrequiledpriortoirutallalionoftheOWTS. Allscpticsystcmcomponenlsshallbcstakedinlhefield
fo approval by the Enginær ¡rrior to excavation
During initialçomtruction the engin0s will ewluâtc the soils in the Rbsorption trcûlmnt field excavalions Lo mnfi¡m
soil co¡ditiom ûnd make adjustmmts as needcd. All septic system cornponslts 8nd trench inslallatio¡s are to be
lpproved by the Engincer prior to trackfllling. County Rcgulations rcguite lhat thc Enginecm ofrccord pcrfom site
irìspectiom of the permitled Ëyslem during construction axl providc "As'Conslructql" documcntation oflhe inslalled
systen to the County aller construclion is çonrplete. All installation will be inspected field msured, reporlcd and
delineated in lhe æüific8tion lettÈr sild record ùrwing. The contrûctor nceds lo photo docurnenl all O\YTS
co¡ì$fuction phass snd supply pholos to the Engineer.
The County EnvironmenÎÂl flffilth dçart¡nent should be contacled at leûst 48 houß prior to fnal backfill of
conponentstoproyidead\äncednoticsofconstructionschechrle inordotopcformâfins¡ißpectionoftheinplace
componenis. The Oarlìcld County conlacl is:
Ted Whi(q P.8., Environmmial Health Specialisl Ill.Garlìcld County Public l{ealth;
twh¡te(ùsarfield-cwnty.con, 970-945-6ó14 x 8 106 (rmin office) or 9?0-230-2442 (mobile)
lipaulding Residmce
owTs, t044t c.R.3r I
SË Job No. 3 1094.01
Msy 25, 20?l
Pagç4
OWS Operatlon ¡nd M¡lntenânce
Owne*hip of thc s¡atsm ûnd respoûsibility for maintenance md rcpûir will renain with the property Omm. The
Ownc is mcouraged !o relai¡l tlË swic6 of qualified personnel to ilspect the OWTS and to perform all meintffice
and rcpairs necesslry ro emure thût the system compments ole rmintdired in gmd opËathtg condition ild suilable
vegetûriye cov€r is sitablished on the ñeldÊ. The componcnls of lhe OWTS system should inspecls¡ within 30 &ys of
being placed ¡nto operat¡on and sh$ld becn inspæfed ând maintained bi-annually, The tank, absorptiou field â}1d
oths sysþm componmts shflld be yisually inspæted bi-amuûlly for debriß, dalüge, leaks, or other pote¡tial
problems. ln gmml for a proprly utiliæd systqq septic tanks should be pumped evcy 3 - Syeañ. The efflumt
fîher should bð clmed every six months and ¡1 thc limc of purping. Absorption fields should be maintainsl vilh
ıuitrble vegÊtativc cove and kept frce ofroot invåsive plunts. Positive surface d¡aimgc arvay from the absorption
field shmld be m¡intained.
lfyou have my qumtion or necd sny additìonal infonnation, pleasc mll'
Sincerely,
SOPRIS ENçINEERING, LLC
./-7 / .fr .t¿'
, lri:j )z */ * y'"r;**k " -' *
Paul E. Rutledge
Design Engineer
2t]377
20!1?é,