HomeMy WebLinkAboutOWTS - STA Soil Expansion Design Packet 04.04.2026129 Cains Lane
Carbondale, CO 81623
970.309.5259
carla.ostberg@gmail.com
April 4, 2026 Project No. C2021
Michele Martin
martinmichele@mac.com
Onsite Wastewater Treatment System Inspection / Soil Treatment Area (STA) Expansion
Bedroom Addition (total 4 bedrooms)
89 Sage Swale
Garfield County, Colorado
Michele,
CBO Inc. has completed an onsite wastewater treatment system (OWTS) inspection and is providing
specifications for expansion of the soil treatment area (STA) for the subject OWTS. The 11.42-acre
property is located outside of Carbondale, in an area where OWTSs are necessary. Our original
documents dated March 2, 2026 did not account for the lower-level finished floor elevation of the addition
and the fact that the existing portion of the residence is slab-on-grade with challenges connecting to the
existing plumbing.
Legal Description: Section: 14 Township: 7 Range: 88 Subdivision: PINYON PEAKS SUB-1ST
AMENDED Lot: 12 11.42 ACRES
Parcel ID: 2393-142-03-012
SITE CONDITIONS The property is currently developed with a 3-bedroom residence. The residence is served by an existing
OWTS. The OWTS consists of a 1250-gallon, two-compartment concrete septic tank followed by a
gravelless chamber trench soil treatment area (STA) with four trenches, with a total of 53 ‘Quick 4’
Infiltrator® chambers (possibly three trenches with 13 chambers and one trench with 14 chambers).
Garfield County Permit SEPT-09-17-4959 documents the system. The system was sized to
accommodate 3-bedrooms and the permit received final approval on January 19, 2018.
The system was inspected by Altitude Septic on July 10, 2023 and verified the septic tank was 1250-
gallons. A screen-shot of the report and invoice is enclosed.
A bedroom addition is proposed, which will result in 4 total bedrooms.
OWTS INSPECTION
We visited the property and performed an inspection of the OWTS on February 10, 2026.
We observed clean outs near the residence and near the detached garage. The septic tank manhole lids
were accessible from grade with 3-feet of risers and located to the north of the driveway. Both inlet and
outlet sanitary tees were present with an effluent filter on the outlet side of the septic tank. Liquid levels
in the septic tank were normal at the time of our inspection.
Page 2
The distribution box was accessible from grade with four outlets. The layout of the STA appears to be
four trenches.
Inspection ports are present at the end of each trench and all were dry at the time of our inspection. We
walked the approximate STA and found no evidence of surface saturation or failure at the time of the
inspection.
This evaluation is not a guarantee of future system performance.
Disclaimer: This inspection is intended only as an evaluation of the present condition of the OWTS
based upon what was observed and the Licensed Inspector’s expertise in onsite wastewater technology.
The Inspector has not been retained to warrant or guarantee the proper functioning of the system for any
period of time in the future. Because of numerous factors which may affect the operation of an OWTS,
as well as the inability of the Inspector to supervise or monitor the use or maintenance of this OWTS, this
report shall not be construed as a warranty by the Inspector that the system will function properly for any
particular prospective buyer, and the Inspector disclaims any warranty, either expressed or implied,
arising from the inspection of the OWTS or this report. The evaluation does not ascertain the impact the
system is having on groundwater.
View of trenches
Page 3
View of septic tank lids Inlet tee
Outlet side of tank with effluent filter Distribution box
Page 4
View of septic tank lids and distribution box Clean out near garage
Clean out near garage clean out near house
Page 5
DESIGN SPECIFICATIONS
Design Calculations:
Average Design Flow = 75 GPD x 2 people/bedroom x 3 Bedrooms + 75 GPD (4th Bedroom) = 525 GPD
LTAR = 0.5 GPD/SF 1
525 GPD / 0.5 GPD/SF = 1050 SF x 1.2 (gravity, bed) x 0.7 (GeoMat™ over min. 6” sand) = 882 SF
(2) 10’ x 44.25’ beds with 6” sand under (3) 39” wide GeoMat™ sheets
The OWTS design is based on 4-bedrooms. Plumbing in the detached garage consists of a dog shower
and is an auxiliary use to the residence. An average daily wastewater flow of 525 GPD will be used.
The addition will route plumbing to a new, 4-inch diameter SDR-35 sewer line with a double-sweep clean out
and a minimum 2% fall to the septic tank. A new, 1000-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 will be installed. The floats should be set to dose approximately 67 gallons
each pump cycle, allowing approximately 16 gallons of drain back. The control panel for the pump
must be located within line of sight of the septic tank. An electrician will be responsible for wiring the
pumping system and the contractor will be responsible for connecting the plumbing. This office should be
contacted for start-up of the system to verify its functioning and to perform a squirt test prior to use of the
system.
Pump Table
Dose Setting 67 gallons/dose 16 gallons drain back (151’ / 1.5”
diameter pump line)
Float Separation 1000 gallon, two-compartment
Valley Precast concrete septic
tank
10” on/off float separation
Pump Criteria 10 gallons per minute (GPM) 6.7 feet total dynamic head
(TDH)
For the purposes of this OWTS design, Benchmark Elevation at grade 6940’ has been established as
100’ (Finished Floor). The Finished Floor elevation of the addition will be 94’ 2 ½” (6934’ 2 ½”). CBO Inc.
should be notified of any discrepancies or problems with grade elevations of proposed components
during installation of the OWTS.
OWTS Component Minimum Elevation
Primary Tank Inlet Invert (New Septic Tank serving
Addition)
Approximate horizontal distance 33’ / min. 2% fall /
min. 8.25” fall
New pump line to tie into existing sewer line at high
point
Approximate horizontal distance 151’ / min. 1% rise
/ min. 18.875” rise
*Elevations are based upon standard OWTS installation practices. Component elevations may change during
installation due to site conditions. Minimum grade refers to piping between components.
The existing 1250-gallon, two-compartment concrete septic tank will remain in use. A handle extension
must be installed on the existing effluent filter for better access.
We assumed there were four trenches, each with at least 13 ‘Quick 4’ Infiltrator® chambers for a total of
53 chambers; however, that configuration does not align with the space available between the inspection
ports and distribution box.
1 The subsurface was evaluated for the original system installation in 2017. Garfield County classified the soils
as Soil Type 2A with an application rate of 0.5 gallons/square foot. We have enclosed Garfield County’s
Inspection Report OWTS and a Subsoil Study by Kumar and Associates.
Page 6
Due to constraints of steep slopes and mature trees, we recommend utilizing the area already cleared
and in use by the existing trenches. These trenches will be replaced with two GeoMat™ beds.
The existing distribution box will be removed and replaced with a new distribution box between the
proposed GeoMat™ beds. The distribution box must be accessible from grade and must have flow
equalizers, or similar product, installed on each outlet pipe in the distribution box to assure equal flow to
each lateral.
The STA will consist of two 10’ x 44.25’ beds with 6-inches of sand filter material placed in the bed
excavation. Sand filter material must be clean, coarse sand, all passing a screen having four meshes to the
inch. The sand must have an effective size between 0.15 and 0.60 mm. The uniformity coefficient must be
7.0 or less. Material meeting ASTM 33, for concrete sand, with three percent or less fines passing 200 mesh
sieve may be used. A gradation of the sand media must be submitted to this office prior to
obtaining the sand.
Three 39” wide GeoMat™ sheets will be placed on top of the sand filter material the entire length of the
bed. A 4-inch diameter perforated pipe will be placed down the center of each GeoMat™ sheet, under
the top layer of fabric. The STA will consist of a total of 265.5 linear feet of 39-inch wide GeoMat™. All
material associated with the GeoMat™ installation must be proprietary products associated with the
GeoMat™, including the geotextile fabric. Manufacturer instructions must be followed regarding installation
of the GeoMat™.
Inspection ports must be installed at each corner of the bed. Clean out ports will also be tied onto the
end of each lateral. Ports may be cut to grade and placed in sprinkler boxes for access. There shall be
no cobble-sized (<2.5”) or greater rock in final cover over the GeoMat™.
COMPONENT SPECIFICATIONS
The component manufacturers are typical of applications used by contractors and engineers in this area.
CBO Inc. must approve alternative components prior to installation of the OWTS. Requests must
be submitted, in writing, to our office for approval prior to installation. Component technical data
sheets are available upon request.
COMPONENT MANUFACTURER MODEL NO. COMMENTS
Septic Tank Valley Precast Item #1000T-2CP-HH 1000-gallon, two-compartment concrete septic tank with high head pump Pump Orenco® PF300511 ½ HP 120 Volt
Biotube ProPak Pump Package Orenco® BPP30DD Vault, Filter, Control Panel (demand dose) Risers and Lids Orenco® Double-walled PVC Risers and Lids (24” diameter) Distribution Box Polylok Min. 6 outlets, risers, lid, (6) speed levelers GeoMat™ GeoMatrix Systems, LLC 39” wide sheets 266’ GeoMat™
Construction must be according to the jurisdiction’s adopted On-Site Wastewater Treatment System
Regulations, the OWTS Permit, and this design.
Page 7
PERMIT APPLICATION INSTRUCTIONS
An OWTS Permit Application must be submitted to Garfield County Environmental Health Department.
https://www.garfield-county.com/environmental-health/filesgcco/sites/16/OWTS-Application-Complete-
Packet-Dec.-2019.pdf. If the OWTS Permit Application will be submitted with a Building Permit
Application, it should be submitted directly to Garfield County Building Department.
All questions regarding permit submission can be directed to Garfield County Environmental Health
Department, 970-945-6614 x8150.
VALIDITY PERIOD OF DESIGN DOCUMENTS
This design is valid for submission of an application for permitting for two (2) years from the date of the
design packet or upon a change in the county OWTS Regulation that could impact compliance with code
requirements. Continued use beyond this period or following a change in the regulation is not
recommended without review and update of design documents.
INSTALLATION CONTRACTOR
CBO Inc. expects that the installer be experienced and qualified to perform the scope of work outlined in this
design. The installer must review this design thoroughly and coordinate with our office in advance of
installation. Any additional conditions in this design or county permit must be completed and documented
prior to final approval of the OWTS installation. Communication between the installer and this office is
expected throughout the installation.
INSTALLATION OBSERVATIONS CBO Inc. must view the OWTS during construction. The OWTS observation should be performed before
backfill, after placement of OWTS components. Septic tanks, distribution devices, pumps, dosing
siphons, and other plumbing, as applicable, must also be observed. CBO Inc. should be notified 48 hours
in advance to observe the installation.
In an effort to improve the accuracy of the record drawing, we request that the installer provide a
sketch of the installation, including path of the sewer lines, water line installation (if applicable),
septic tank location, STA location, and measurements from building corners or another fixed
objects on the property. This sketch is most easily provided on Sheet W2.0 of the OWTS Design
Packet. Photographs of the installation and final cover are also requested to supplement our installation
documentation.
REVEGETATION REQUIREMENTS
An adequate layer of good quality topsoil capable of supporting revegetation shall be placed over the entire
disturbed area of the OWTS installation. A mixture of native grass seed that has good soil stabilizing
characteristics (but without taproots), provides a maximum transpiration rate, and competes well with
successional species. No trees or shrubs, or any vegetation requiring regular irrigation shall be placed over
the STA. Until vegetation is reestablished, erosion and sediment control measures shall be implemented
and maintained on site. The owner of the OWTS shall be responsible for maintaining proper vegetation
cover.
OPERATION INFORMATION AND MAINTENANCE
The property owner shall be responsible for the operation and maintenance of each OWTS servicing the
property. The property owner is responsible for maintaining service contracts for manufactured units,
alternating STAs, and any other components needing maintenance.
Page 8
Geo-fabrics or plastics should not be used over the STA. No heavy equipment, machinery, or materials
should be placed on the backfilled STA. Machines with tracks (not wheels) should be used during
construction of the STA for better weight distribution. Livestock should not graze on the STA. Plumbing
fixtures should be checked to ensure that no additional water is being discharged to OWTS. For example, a
running toilet or leaky faucet can discharge hundreds of gallons of water a day and harm a STA.
If an effluent filter or screen has been installed in the OWTS, we recommend this filter or screen be cleaned
annually, or as needed. If the OWTS consists of a pressurized pump system, we recommend the laterals be
flushed annually, or as needed.
The homeowner should pump the septic tank every two years, or as needed gauged by measurement of
solids in the tank. Garbage disposal use should be minimized, and non-biodegradable materials should not
be placed into the OWTS. Grease should not be placed in household drains. Loading from a water softener
should not be discharged into the OWTS. No hazardous wastes should be directed into the OWTS.
Mechanical room drains should not discharge into the OWTS. The OWTS is engineered for domestic waste
only.
ADDITIONAL CONSTRUCTION NOTES If design includes a pump, weep holes must be installed to allow pump lines to drain to minimize risk of
freezing. The pump shall have an audible and visual alarm notification in the event of excessively high-
water conditions and shall be connected to a control breaker separate from the high-water alarm breaker
and from any other control system circuits. The pump system shall have a switch so the pump can be
manually operated.
Excavation equipment must not drive in the excavation of the STA due to the potential to compact soil.
Extensions should be placed on all septic tank components to allow access to them from existing grade.
Backfill over the STA must be uniform and granular with no material greater than minus 3-inch.
LIMITS: The design is based on information submitted. If soil conditions encountered are different from conditions
described in this report, CBO Inc. should be notified. All OWTS construction must be according to the
county regulations. Requirements not specified in this report must follow applicable county regulations.
The contractor should have documented and demonstrated knowledge of the requirements and
regulations of the county in which they are working. Licensing of Systems Contractors may be required
by county regulation.
Please call with questions.
Sincerely,
Carla Ostberg, MPH, REHS
NAWT Certified Inspector
Certification # 11044ITC Exp. April 2028
Pump Selection for a Non-Pressurized System - Single Family Residence Project
89 Sage Swale
Parameters
Discharge Assembly Size
Transport Length
Transport Pipe Class
Transport Line Size
Distributing Valve Model
Max Elevation Lift
Design Flow Rate
Flow Meter
'Add-on' Friction Losses
1.25
151
40
1.50
None
5
10
None
0
inches
feet
inches
feet
gpm
inches
feet
Calculations
Transport Velocity 1.6 fps
Frictional Head Losses
Loss through Discharge
Loss in Transport
Loss through Valve
Loss through Flowmeter
'Add-on' Friction Losses
0.7
1.0
0.0
0.0
0.0
feet
feet
feet
feet
feet
Pipe Volumes
Vol of Transport Line 15.9 gals
Minimum Pump Requirements
Design Flow Rate
Total Dynamic Head
10.0
6.7
gpm
feet
0 5 10 15 20 25 30 35 40
0
50
100
150
200
250
300
Net Discharge (gpm)
PumpData
PF3005 High Head Effluent Pump
30 GPM, 1/2HP
115/230V 1Ø 60Hz, 200V 3Ø 60Hz
PF3007 High Head Effluent Pump
30 GPM, 3/4HP
230V 1Ø 60Hz, 200/460V 3Ø 60Hz
PF3010 High Head Effluent Pump
30 GPM, 1HP
230V 1Ø 60Hz, 200/460V 3Ø 60Hz
PF3015 High Head Effluent Pump
30 GPM, 1-1/2HP
230V 1Ø 60Hz, 200/230/460V 3Ø 60Hz
Legend
System Curve:
Pump Curve:
Pump Optimal Range:
Operating Point:
Design Point:
Date: lo -/9--/7
Location: . 9a2ere_
Inspection Report OWTS
Owner: Svu,e. .25 tfG- 4Z- 7 IC 7
OWTS Design Worksheet:
Number of Bedrooms 3 -I /000
II. Design Flow Table 6-1
III. Soil Evaluation- Soil type
Profile Hole Notes 647
Ave. Perc. Rate
4t 3'
Long Term Acceptance Rate (LTAR) Table 10-1
IV. Determine Soil Treatment Area (STA))
STA = Design Now (Gal/dav) = Y.10 (Gal/day)
LTAR (Gal/day/sq.ft.) (Gal/day/sq.ft.)
V. Size Adjustment Factors -Methods of Application and Types of Distribution Table 10-2 and Table 10-3.
t520 sq. ft.
Trench v"
Bed
Chambers
Other options
Design Treatment Area = STA sq.ft
Design Treatment Ar'a = g9D0
Design Treatment Area =
x Application Factor x Storage/Distribution Factor.
sq.ft x i 7 Ar 6"3o
sq.ft.
VI. Number of Chambers.
Design Treatment Area sq.ft. = Number of Chambers
Sq. ft. pet- chamber
General Notes and Directions to Installer:
12,
J
nW
View Map
MM CONCEPTS LLC
2212 RIVER HILL
AUSTIN TX 78733
Building #1
Units 1
Building Type SFR
Abstract Codes / (Property Type)SINGLE FAM.RES-IMPROVEMTS-1212 (RESIDENTIAL PROPERTY)
Architectural Style 1-STORY
Stories 1
Frame WOOD FRAME
Actual Year Built 2018
Gross Living Area 2,250
Total Heated SqFt 2,250
Bedrooms 3
Baths 2
Heating Fuel GAS
Heating Type HT WTR RAD
Roof Type GABLE
Roof Cover PREFAB MET
Summary
Account R111661
Parcel 239314203012
Property
Address
89 SAGE SWALE RD, CARBONDALE, CO 81623
Legal
Description
Section: 14 Township: 7 Range: 88 Subdivision: PINYON PEAKS
SUB-1ST AMENDED Lot: 12 11.42 ACRES
Acres 11.42
Land SqFt 0
Tax Area 11
Mill Levy 76.1560
Subdivision PINYON PEAKS SUB-1ST AMENDED
Map
Owner
Land
Unit Type SINGLE FAM.RES.-LAND - 1112 (RESIDENTIAL PROPERTY)
Square Feet 0
Acres 11.42
Buildings
Garfield County, CO
2/6/26, 3:59 PM qPublic - Garfield County, CO - Property Record Card: R111661
https://qpublic.schneidercorp.com/Application.aspx?AppID=1038&LayerID=22381&PageTypeID=4&PageID=9447&Q=635515754&KeyValue=R111661 1/3
Tax Year 2025 2024 2023 2022 2021
Actual Value $1,669,190.00 $1,381,810.00 $1,381,810.00 $881,100.00 $881,100.00
Tax Year 2025 2024 2023 2022 2021
Non School Assessed Value $104,320.00 n/a n/a n/a n/a
School Assessed Value $117,680.00 n/a n/a n/a n/a
Pre 2025 Assessed Value n/a $92,580.00 $92,580.00 $61,240.00 $63,000.00
*House Bill 24B-1001 established a separate assessment rate for school district residential properties, effective for the 2025 tax year and beyond. Click here for Assessor
FAQs
Tax Year 2025 2024 2023 2022 2021
Non School District Levy 34.701 n/a n/a n/a n/a
School District Levy 41.455 n/a n/a n/a n/a
Total Levy 76.156 74.414 72.518 81.029 79.776
Tax Year 2025 2024 2023 2022 2021
Non School Taxes $3,620.00
School Taxes $4,878.44
Taxes Billed $8,498.44 $6,889.24 $6,713.72 $4,962.20 $5,025.88
Click here to view the tax information for this parcel on the Garfield County Treasurer's website.
Sale Date Deed Type Reception Number Book - Page Sale Price
8/4/2023 SPECIAL WARRANTY DEED 988322 $2,050,000
7/28/2023 STATEMENT OF AUTHORITY 988323 $0
7/3/2023 STATEMENT OF AUTHORITY 988321 $0
9/4/2017 BARGAIN AND SALE DEED 897288 $0
9/4/2017 STATEMENT OF AUTHORITY 897287 $0
4/18/2017 WARRANTY DEED 891438 $215,000
4/27/2016 STATEMENT OF AUTHORITY 878622 $0
12/1/2009 STATEMENT OF AUTHORITY 778532 $0
9/1/2005 WARRANTY DEED 681798 1724-493 $290,000
1/17/2003 WARRANTY DEED 618954 1428-601 $252,500
12/27/1993 SPECIAL WARRANTY DEED 457961 0889-0656 $0
4/9/1993 SPECIAL WARRANTY DEED 446431 0859-0809 $0
11/15/1989 WARRANTY DEED 407559 0767-0373 $77,000
DECLARATION 404671 0761-0053 $0
Click here to view Property Related Public Documents
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Assessed Values
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2/6/26, 3:59 PM qPublic - Garfield County, CO - Property Record Card: R111661
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information possible. No warranties, expressed or implied are provided for the data herein, its
use or interpretation. Data is subject to constant change and its accuracy and completeness
cannot be guaranteed.
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2/6/26, 3:59 PM qPublic - Garfield County, CO - Property Record Card: R111661
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Gar eld County, CO
Developed by
Account Number R111661
Parcel Number 239314203012
Acres 11
Land SqFt 0
Tax Area 011
Mill Levy 76.1560
Physical Address 89 SAGE SWALE RD
CARBONDALE 81623
Owner Address MM CONCEPTS LLC
2212 RIVER HILL
AUSTIN TX 78733
Total Actual Value $0 Last 2 Sales
Date Price
8/4/2023 $2,050,000
4/18/2017 $215,000
Date created: 2/6/2026
Last Data Uploaded: 2/6/2026 2:04:36 AM
374 ft
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