HomeMy WebLinkAboutOWTS Installation Observations 01.23.18January 23,2018
Carlson, David & Hudson, Jeann
1779 County Road 241
New Castle,CO,8L647
"david carl son" al L cul*r'e$t. glech ic@hotma i l. com
RE:AS-BUILT, Orrsitc Wastcwnter Trentntent Systeln (OWTS), Carlsott Residence,
1779 County Road 241, Ncw Castle, Garfield County, Colorado
SE Job No. 17021.01 Parcel Number: Parcel Number: 2125-131-00-037
Dear Dave:
Pursuant to County requircnrents, this letter prnvides dooutnentation that the nerv Ormite Wastervater Treatment
Systems (OWTS) recently installed at the above referenced site is in cornpliance with the petmitted design. The
resiclential OWTS is located on the prnperty desuibed as: Section: l3 Townshipl 5 Range: 9l A Tr In The
Ne, Aka Parrel2 Vix Rarrch Sub-Div Exernption. Sopris Engineering inspected the excavations, soils,
materials ancl the installation of the system componetrts at vat'ious tirnes during constn¡ction, prior to fïnal
backfill and after all installatiotls was completed. The system constructecl on site rvas designed and built to
sewe the needs of residence currently uncler constructio¡r. The installed system was designed rvith a maximum
tleatment capacity equivalent for typical 3-bedroorn home. Sopris Engirreeting pelformed site visits to inspect
and docurnent the as-built conditions of the constrt¡cted system. Inspections were coordinated rvith the orvner
who constrt¡ctecl the system, The as-built conditìons and installation of the nerv OrffTS components is in
compliance rvith Garfield County Regulations; the recommendations and specificatio¡ts delineatecf on the civil
OWTS clesign plan, Cl-OWTS Plan, stamp datecl2-8-2017, by Sopris Engineering. The design criteria and
systenl sizing information is st¡nrmarized belorv. An As-built OWTS recold dtarving is attached delìneating the
As-built descriptions and locatiott of the components.
Desiqn Criteria and As-built,SvsfenlÇomnonent Illstallation
The system rvas clesignecl based on the design criteria approved for r¡se of Soil Trcatment Unit (STU) systems.
The OWTS inclr¡des the installation of a 1000 gallon 2-compaftrnent septic tank with risers and lids installed at
the sur.face. The ta¡rk rvas installed rvith arr inlet sanitary tee and an outlet effluent fìlter sanitary tee. A gtavity
schedule-4O server pipe rvitlr a cleanout is installed fi'orn the residence to the tank. The soil treatment unit
(STU), consists of 3 leaching charnber trenohes that provides 400 S.F. of total absorption area. I'he septic tank
eflluent is equally distributed by gravity, via a distributiott box, to the STU. The effluent is distributed through
a distribution box installed rvith risers ancl liclat the surface and individual distribution pipes connected to the
head encl cap of each chamber trench. Observation ports rvith caps were instnlled on each end chamber r¡nit,
The clesign ib ín cornpliance rvith the cr¡n'ent County regulations rvith design calculations basecl on the soil
type, textute and structure rvith an appropriate long tetnt acceptflnce rate (LTAR).
502 Main Slreet a Suite A3 a Carbondale, C0 B1ô23 a 970 704-031 1 a Fax 970 704-031 3
$oPnts Ettcmtlnllui . llG civil consultants
AS-BUILT, OIWTS
Carlson Residence
SE Job No. 17021.01
Jannary 23,2018
Sub Surface Contlitions anel observation
Sr¡bsurface soil investigations and USDA soil textt¡re method tests were performed in the fielclexcavation
by Sopris Engineering on April 3,2017. The soils in the area of the proposecl absorption field were
sampled ancl chamcterized by application of the USDA soil texturB rnethod analysis. The soils were tested
to determine the hyclraulíc loading rate and to con-firm the appropriate absorptive surface level suitable for
conventional absorption systems in native soils. The soils below nil to 3 inches of topsoil consist of
medium dense gravelly loamy sand to loamy sancl soil with scatterecl cobbles to 6 feet below the surface.
The unclerlying soils are composecl of mixed alluvial materials consisting of gravels & cobbles in a sand
rnatrix. The soil appears to be consistent across the site.
The native soils sarnpled fiom 2-3 feet below the surface arc characterized as a soil type I consisting of
sand to loamy sand textue with single granular structure. This soil has an effective loading mte for
conventional soil treatment of 0.8 Gal/S.F./clay fot a level 1 conventional treatment system. The equivalent
percolation mte is asstunecl to be 5-10 rninutes per inch. Due to tlre prcsence of scattered cobbles and
gravels, the deslgn included the placernent of a minimum of 4" of concrete sand in the bottom <lf the
excavated trenches to provide a leveling course and to protnote unifortn disttibution actoss the
heatment/absorption meclia.
No fiee water \ryas encountered in excavations o¡r site. Seasonal high Grounclwater levels ale expected to be
below 7 feet from the existing surface grades. The soils wete found suitable for a shallow conventional
shallow absorption field consisting of glavelless infiltration charnber units.
Desien Florv
The design flow is calct¡lated as follows:
The new OWTS shall be based on a minimum 3-bedrooru capacity for single family residence.
From the Garfield County OWTS Regulation 43 ;
Minimum population based on 3 bedrooms @ 2 petson /beclroom : 6 persons,
Gallons per day per percon =75 gal/person/day, No peaking factor
Max. Design florv (Qd) gallons/clay = (# ofpeople) x (avg. flow)gal/person/day.
Design flow Qd:6*75=450 gpd
Treatment-Soil Trentment Unit/ Absorptiorl Systeq Desig+
The treatment/absorption fielcl was clesignecl based on utilizing the effective Long Term Acceptance Rate
(LTAR) for the native soils and the application of appropriate loading factors for a soil trcatment unit
system utilizing gravity distribution to gravelless chamber trenches. The new treatrne¡rt system and
absorption field consist of gravity distribution of septic tank effluent via a distribution box to inclividual
chamber trenches with trealment acloss the native soil absorptive sutface.
Long Term Acceptance Rate (LTAR)
Consiclering the application of the new state regulation 43:
Receiving Wastewater Trcatment Level 1; LTAR loarny sand is (0.80 gal./S.F./clay) for soil type 1.;
Loacling factors; (Table l0-2, Gravity trenches: 1.0) ancl (Table l0-3, gmvelless chambers = 0.7)