HomeMy WebLinkAboutEngineer's ReportSeptember 29, 2014
Rock Leonard
580 Main Street
Carbondale Colorado 81623
RE: AS -BUILT, On-site Wastewater Treatment System (OWTS), Parcel 3, Faranhyll Ranch
SE Project No. 14033.02, Parcel Number: 239510300132
Rock:
Pursuant to County requirements, this letter provides documentation that the new Onsite Wastewater
Treatment Systems (OWTS) recently installed at the above referenced site is in compliance with the
permitted designs. Sopris Engineering inspected the excavations, soils, materials and the installation of
the system components at various times during construction, prior to final backfill and after all installations
was complete. The OWTS constructed on site consisted of a new treatment/absorption field, septic tank,
distribution piping and distribution box. The OWTS was designed and built to serve the needs of the new
3 -bedroom residential structure. Sopris Engineering performed several visits to inspect and document the
as built conditions of the constructed system. We have coordinated our efforts with the earthmoving
contractor that modified and constructed the new system components. The as built conditions and
installation of the new OWTS components is in compliance with Garfield County Regulations and the
design presented in the Sopris Engineering design drawing, dated April 16, 2014. An As -built OWTS
record drawing is attached delineating the As -built descriptions and location of the components.
As -built System Component Installation
A new two chamber 1000 gallon concrete septic tank, two geotextile sand filter (GSF) beds and a
distribution box were installed within the approved activity envelope. The septic tank access openings were
fitted with concrete risers and lids at the surface. A 4" effluent filter was installed in the tank outlet
sanitary tee. The tank is watertight and was set level. A cleanout is installed on the sewage line offthe
exterior wall of the residence.
Treatment/Absorption field: The installed treatment/absorption field contains 30 In Drain units (model
EL00924) with four GSF rows containing 6 units per row. The Elgen In -Drain units were placed at 4 feet
on center over a 12 -inch deep filter sand layer (concrete sand) bed approximately 30 feet long by 18 feet
wide. The bed has an average excavation depth of 30 to 36 inches from finish grade and was constructed
level. Effluent from the septic tank discharges to an 8 port concrete distribution box, installed with risers
and access lid at the finish surface grade. Four individual distribution lines are installed to the head of each
GSF row to equally distribute effluent through the perforated distribution laterals installed on the top of
each row of In -Drain units. The 4" SDR -35 lateral pipe, installed level, runs the full Iength of the GSF row
and is capped with a swept 90 degree fitting and inspection port pipe riser on each end. A 4" vertical
piezometer inspection port is installed near the comer of the bed opposite the D -Box.
A subsurface soil investigation was performed by HP Geotechnical and USDA soil texture method tests
were performed by Sopris Engineering in the area of the new proposed secondary treatment absorption
502 Main Street • Suite A3 0 Carbondale, CO 81623 0 (970) 704-0311 0 Fax (970) 704-0313
Sornis ENCINEERING • LLC
civil consultants
AS -BUILT OWTS, Parcel 3, Faranhyll Ranch
SE Job No. 14033.02
September 29, 2014
Page 2
fields. Three percolation test holes and one profile pits was excavated by a backhoe approximately 8 feet
deep to allow observation of the soils in the area of the proposed field. The average percolation rate was
calculated to be 23 mpi. The soils below 1 to 1 1/2 feet of topsoil consist of sandy clayey loam material
(USDA: loam, Soil type 2). No free water was encountered in the exploration pit. Groundwater levels are
expected to be below a minimum of 10 feet from the existing surface grades. The soils are suitable for
treatment/absorption beds. The soils in the excavations at the sand soil interface were tested by the
engineer and confirmed to be consistent with the geotechnical description and characterized as loam.
OWS Operation and Maintenance
Ownership of the system and responsibility for maintenance and repair will remain with the property
Owner. The owner is responsible for maintaining suitable vegetative cover on the beds. The components
of the OWS system should inspected within 30 days of being placed into operation and should been
inspected and maintained bi-annually. The tank, absorption field and other system components should be
visually inspected annually. In general, for a properly utilized system, septic tanks should be pumped every
3 - 4 years. The effluent filter should be cleaned annually and at the time of pumping. Absorption fields
should be maintained with suitable vegetative cover and kept free of root invasive plants. Positive surface
drainage away from the absorption field should be maintained.
If you have any question or need any additional information, please call
Sincerely,
SOPRIS ENGINEERING, LLC
Paul Rutledge Yancy
Design Engineer Principa
Cc: Garfield County Building Department