HomeMy WebLinkAboutEngineer's ReportApril 4, 2013
CBO Inc.
33 Four Wheel Drive Road
Carbondale, CO 81623
cell) 970-309-5259 office) 970-704-0484
carla.ostberg(c�gmail.com
Richard Collins
Aspenbubba5@msn.com
Onsite Wastewater Treatment System (OWTS) Inspection
4501 CR 233
Garfield County, Colorado
Richard,
As requested, CBO Inc. performed an Onsite Wastewater Treatment System (OWTS)
inspection at 4501 CR 233, Silt, CO.
A partial system design from Gamba and Associates dated February 21, 2000, Project
00114 was provided. Details of a 1000 -gallon, two compartment tank and a dosing
chamber with a pump system are consistent with findings on-site. A mounded absorption
area, located to the west of the building, is also consistent with Gamba and Associates'
Project 00114 detailing three rows of six gravelless standard Infiltrator® chambers totaling
18 chambers.
The septic tank appeared to be in good condition. The liquid level in the tank was normal.
There was no inlet tee, but there was an outlet tee with an effluent filter. There was no
scum layer in the tank. Sludge depth was 5" in the first compartment and 3" in the second
compartment. There was no scum later in either compartment. There is no need to pump
the septic tank at this time. The pump chamber also appeared to be in good condition.
Water was run through the system and the pump kicked on. Water was observed through
the observation ports in the absorption area after the pump kicked on. Prior to running the
pump, the absorption area was dry, viewed from all three observation ports. The absorption
area showed no signs of saturation, and had no indication of failure. The pump alarm was
also tested and found to be functional.
Current fixtures in the building include a toilet, hand sink, and kitchen sink. The building is
used as a nursery and office with typically one employee for an 8 -hour shift. We will use a
maximum of 3 employees using the facility per day.
Fixtures = 37.6 gallons/day x 3 employees = 113 gallons/day = Average Daily Flow
Design Flow = Q = 113 x 1.5 = 170 gallons/day
Min Tank Capacity = 170 gallons/day x 30 hour retention time = 213 gallons minimum
EXISTING 1000 gallons + pump chamber
Min Absorption area assuming conservative 40 mpi = (Q x sq rt 40) / 5 = 300 square feet
Taking a 50% reduction for dosing and gravelless chambers = 150 square feet
EXITING 279 square feet, assuming 15.5 sq ft per chamber x 18 chambers
This system was found to be working properly and is sized adequately for the proposed use
of no more than 3 employees, working an 8 -hour shift, using fixtures including a toilet, hand
sink, and kitchen sink.
Recommendations:
Contact Gamba and Associates to access the complete system design — Project
00114. 970-945-2550
Install an inlet tee on the septic tank.
Install risers on the tank so the tank is accessible from grade (currently, lids are
approximately 2 -feet below grade).
The effluent filter should be checked annually and cleaned, as needed.
The septic tank should be pumped, as needed. (solids equaling approximately 25-
33% of tank capacity, or 12-18" of sludge and scum layers combined)
This evaluation is not a guarantee of future system performance. Please call with
questions.
Sincerely,
Ca/Lt. (tt Os-f-bAs
Carla Ostberg, MPH, REHS
NAWT Certified Inspector
Certification # ITC11042010 Exp. 2014
Excavating tank lids for accessibility.
1st compartment (no inlet tee)
2nd compartment (outlet tee and effluent filter)
Pump chamber with pump
Mounded absorption area