HomeMy WebLinkAboutOWTS Installation Observation 07.06.2026CBO Inc.
129 Cains Lane
Carbondale, CO 81623
970.309.5259
carla.ostberg@gmail.com
June 20, 2026 Project No. C2020
Ryan Margo
rmargo@crms.org
Onsite Wastewater Treatment System (OWTS) Installation Observations
124 CR 108 (Thompson Creek Road)
Garfield County, Colorado
Permit SEPT-9685
Ryan,
CBO Inc. observed the installation of the onsite wastewater treatment system (OWTS) on March 25, and
April 9, 2026 for the subject property. Altitude Septic installed the system.
The OWTS design is based on 3 bedrooms in the existing residence with a possible future addition of a
4th bedroom. An average daily wastewater flow of 525 GPD was used.
The existing septic tank was abandoned by pumping the tank and crushing the top, bottom, and sides
and filling in the void with onsite materials. The existing STA was abandoned in place.
Setbacks to the well, ditch, and water line were verified.
The existing cast iron sewer line was replaced as close to the foundation as feasible. Cured in-place
pipe (CIPP) lining may be considered for any remaining cast iron sewer line. The new 4-inch SDR-35
sewer line exiting the residence has a double-sweep clean out and a minimum 2% grade to the septic
tank.
The system installation included a 1500-gallon, two-compartment Valley Precast concrete septic tank
with an Orenco® Biotube Pump Vault and an Orenco® PF3005 pump in the second compartment of the
septic tank. The floats were set to dose approximately 65 gallons each pump cycle. The control panel for
the pump is located within line of sight of the septic tank. Valley Precast out of Buena Vista performed start-
up of the pumping system. We tested the pump and alarm as well as cycled through the automatic
distributing valve (ADV) and ran a squirt test achieving heights approximately 5-feet above grade in each
zone.
Effluent is pumped through a 1.5-inch diameter pump line from the pump chamber to an Orenco® ADV,
model 6402. This pump line had a minimum 1% grade for proper drain back into the tank after each pump
cycle. The ADV was placed at a high point in the system in an insulated riser with access from grade.
Effluent is pressure dosed to through 1.5-inch diameter distribution lines to a 13’ x 50.5’ bed. A minimum of
3-feet of sand filter material was installed in the over-excavated footprints. A gradation of the sand media
is enclosed.
Laterals must be 1.5-inches in diameter with 5/32-inch diameter orifices facing down, spaced 3-feet on
center, installed on the GeoMat™ with the filter fabric over the laterals. Four 39” wide GeoMat™ sheets were
be placed on the 13-foot wide bed.
Each 1.5-inch diameter lateral ends in a sweeping ell facing up with a ball valve for flushing. Valves were
placed in a 10-inch sprinkler box for access. Laterals were covered by a soil separation fabric and at least
1-foot of topsoil or other suitable soil able to support vegetative growth. Rocks were placed around the sand
filter to prevent unintended traffic.
The OWTS was generally installed according to specifications. This observation is not a guarantee of
workmanship and/or parts and materials. CBO Inc. should be notified if changes are made to the OWTS
in the future. Any additional OWTS construction must be according to the county regulations.
LIMITS: Observations are limited to components that are visible at the time of the inspection. The installer must
have documented and demonstrated knowledge of the requirements and regulations of the county in
which they are working. The quality of the installation is dependent on the expertise of the installer, soil
type, and weather conditions.
Please call with questions.
Sincerely,
CBO Inc.
Carla Ostberg, MPH, REHS
View of STA (sand filter) Double sweep clean out starting beyond concrete slab
REMINDER: sewer line is cast iron out of the house to the point of the new clean out
Sewer line to septic tank Inlet tee
Slope to septic tank
Pump chamber
Looking from septic tank to control panel
ADV to Sched 40 conduit under access road
Sched 40 conduit Distribution lines to STA
Lateral with orifice shield on geomat, under fabric STA
Squirt test
Boulders placed around STA for protection
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