HomeMy WebLinkAboutOWTS Installation Observations 10.01.18October 1, 2018
Keith and Carrie Brand
1327 West Ridge Court,
Carbondale, CO 81623
keith(@tenalinkstmcture s. com
RE: Certification Letter, On-site'Wastewater Treatment System (OWTS), Brand Residence, TBD Cedar
Street, Lot 204 Amended Lots 12-14, Blk 9, Carbondale, CO
SE Job No. 18065, Parccl No: 2393-284-09-020. Garfield County Permit: SEPT-06-18-5296
Dear Keith:
Pursuant to County requirements, this letter provides documentation that the new Onsite Wastewater
Treatment System (OWTS) recently installed at the above referenced site is in compliance with the
permitted design. Sopris Engineering inspected the excavations, soils, materials and the installation of the
system components at various times during construction, prior to final backhll and after all installations
were completed. The system constructed on site was designed and built to serve the needs of the single
family residential structure and accessory building unit. The installed residential system was designed for a
maximum 3-bedroom residence. Sopris Engineering performed several visits to inspect the as built
conditions of the constructed system. We have coordinated our efforts with the earthmoving contractor,
that constructed the system. The as built conditions and installation of the new OWTS components is in
compliance with Garfield County OWTS Regulations; the recommendations and specifications delineated on
the civil design plans, C2-OWTS & the OWTS Design Report, dated6-7-2018, by Sopris Engineering. The design
criteria and system sizing information is summarized below. The As-built OWTS treatment bed has been
constructed in the locations shown on the attached As-Built Record Drawing. The OWTS installation was
performed by Pifco Excavating & Trucking,372 Crystal Park Dr, Carbondale, CO 81623, (970) 963-8176.
Desisn Criteria and As-built Svstem Comnonent Installation and Sizing
The system was designed based on the design criteria approved for use of pressure dose sand filters (SF) systems.
The OWTS includes the installation of a 1,250 gallon 2-compartment septic tank with a total of 1000 gallon septic
capacity in the primary and secondary tank chambers. The second tank compartment serves as a dosing vault with a
simplex effluent pump housed in an Orenco bio-tube basin assembly. The effluent is equally pressure distributed
across the treatmenlabsorption SF field via individual custom perforated distribution pipes connected at the head of
each SF row distribution row. Gravity sewer pipes with two-way cleanouts were installed from the plumbed
buildings to the tank.
Design Calculations OWTS
Installed OWTS with a minimum 3-bedroom capacity.
Minimum population based on 3 bedrooms : 6 persons.
Gallons per day per person:75 gallperson/day, No peaking factor
Max. Design flow (Qd)gallonslday: (# of people) x (avg. flow)gallperson/day
Design flow Qd :6*75:450 Wd
502 Main Street a Suite A3 tr Carbondale c0 81623 ! (970) 704-0311 ! Fax (970) 704-0313
$oPnrs IttGlnItRmG o llG civil consultants
O\ryTS Certification Letter
Brand Residence
SE Job No. 18065.01
October I,2018
Page2
Septic Tank: installe<l a 1250 gallorr, two compartment septic tank with a bio-tubc dosing assembly in thc sccond
çompaxtment.
Sub Surface Conditions a.nd Testing
Subsurface soil investigations and USDA soil textwe method tests were performed by Sopris Engineering. The soils
in the area of the proposed absorption field were sampled and charactenzedby application of the USDA soil texture
method test. The soils below nil to 3 inches of topsoil consist of medium dense gravelly loamy sand material to 1.5
to 6 feet below the surface. The soil appeared to be consistent across the site.
The native soils sampled from 2-3 feet below the surface are characterized as a soil type I consisting of loamy sand
texture with moderate granular structure. This soil has an effective loading rate for conventional soil treatment of
0.0.8 Gal/S.F.lday for a level I conventional treatment system. Due to limited area and to provide optimal treatment
a fully pressure dosed intermittent sand filter was installed. No free water was encountered in excavations on site.
Groundwater levels are expected to be below 10 feet from the existing surface grades.
Intermittent Sand Fitter Treatment Unit/ Absorption Svstem Deqisn
The treatment/absorption field installed was designed based on utilizing the effective Long Term Acceptance Rate
(LTAR) for an intermittent sand filter treatment system utilizing pressure dosed distribution laterals and gravelless
chamber units as spray shields.. The new treatment system consist of a fully pressure dosed sand filter Treatment
bed System with a specified layer of filter sand (ASTM-33, "Concrete sand").
Long Term Acceptance Rate (LTAR)
Considering the application of the new state regulation 43:
Receiving Wastewater Treatment Level 1; loading rate for sand filter is (1.0 gal./S.F./day) for the minimum 36"
depth of treatment media;
Loading factors; (Table 10-2, pressure dosed application bed: 1.0 )
A(sf): Od.:
LTAR
A: Area;
LTAR: 1.0 GaVS.F.lday for ASTM-33, "Concrete sand"
Qd: flow (gaVday): 600 gpd
L.F. 1:1.0 pressure dosing
A(sÐ :450 gpd x 1.0 :450 S.F.
1.0 GaVS.F./day
Installed a37.5'by l2' bed backfilled with treatment media consisting of ASTM-33, "Concrete sand"
lnstalled 3 runs of custom perforated distribution laterals on top of the sand layer covered with 36 Quick-4
chambers in 3 rows with 8 chamber units per row for use as pressure dose spray shields, as delineated on the plan.
The bed is dosed from the simplex high head distribution pump system installed in the third compartment of the
septic tank.
The septic t¿nk effluent is pressure dosed from the pump chamber to a manifold pipe at the head of each
distribution lateral rows via a 1.25" discharge pipe installed with a continuous slope to allow drainage into
the field and drainage back into the tank. The effluent is equally pressure dosed through 1.25-inch custom
perforated distribution laterals running the length of the treatment bed rows installed on top of the installed
OWTS Certification Lettel
Brand Residence
SE Job No. 18065.01
Octobel l,2018
Page 3
sand filter meclia. The pipe has 3/16-inch orifices drilled every 2.0 feetoriented upwarcl to spray onto the
infiltrator quick-4 chamber orifice Ball valves are installed on the encl of each distribution laternl centered
below the 4-inch inspection ports on each end chamber. A piezorneter monitoring well pipe riser with
threacled cap was installed near the Northwest colner of the fielcl.
OWS Operation and Maintenance
Ownership of the systern and responsibility for rnaintenance and repair will remain with the propel'ty
Owner. The Orvner is encouragecl to retain the services of qualified perconnel to inspect the OWTS and to
perfomr all maintenance ancl repair:s necessaly to ensure that the system components arc maintained in
good operating condition and st¡itable vegetative cover is established orr the fielcls. The components of the
OWTS system shoulcl inspected lvithin 60 days of being placed into normal operation and should been
inspected ancl maintained bi-annually. The tank, absorption fielcl and other system cornponents shoulcl be
visually inspected bi-annually for debris, damage, leaks, or other potential problems. In geneml, for a
prnperly utilized system, septic tanks should be purnped every 2 - 4 years. The effluent filter should be
cleaned evely six months ancl at the tirne of pumping. Absorption fielcls should be maintained with
suitable vegetative cover ancl kept free of root invasive plants. Positive surface clrainage away from the
absorption field should be maintained.
If you have any question or need any additional infolmation, please call.
Sincerely,
SOPRIS ENGINEERING, LLC
Paul E. Rutledge
Design Engineer
Yancy Nichol, PE
Principal