HomeMy WebLinkAboutEngineer's OWTS Design Plan 2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlestonberry.com
June 17, 2025
Project#03019-0001
Mr. Kyle Byman
kylebyman@icloud.com
Subject: OWTS Design
213 County Road 228
Silt, Colorado
Dear Mr. Byman,
At your request, Huddleston-Berry Engineering & Testing, LLC completed design of an addition
to an existing Onsite Wastewater Treatment System (OWTS) for a new single-family residence
at 213 County Road 228 in Silt, Colorado. The site location is shown on Figure 1 – Site
Location Map. A site plan is included as Figure 2.
Site Description
At the time of the investigation, the center portion of the site was occupied by an existing
residence. In addition, the northern property boundary was occupied by Pretti Lane. The
remainder of the site was open and gradually sloping down to the south. Site topography is
shown on Figure 2. Vegetation consisted primarily of weeds, grasses, and sparse trees. The site
was bordered to the north, west, and south by rural residential/agricultural properties, and to the
east by Pretti Lane.
Subsurface Investigation
As indicated on the logs, the subsurface conditions at the site were consistent. Using visual-
tactile classification methods, the soil profile consisted of 1.0 foot of topsoil above reddish-tan,
moist, medium stiff sandy loam with gravel soils with a moderate granular structure (Soil Type 2
with less than 35% rock) that extended to a depth of 6.0 feet below the existing ground surface.
The sandy loam soils were underlain by reddish-tan, moist, medium stiff silt loam with gravel
soils with a weak granular structure (Soil Type 2A with less than 35% rock) that extended to the
bottoms of the excavations.
Groundwater was not encountered in the subsurface at the time of the investigation. In general,
based upon the results of the subsurface investigation, HBET believes that the seasonal high
groundwater elevation is deeper than 8.0 feet below the existing grade at this site.
The locations of the test pits are shown on Figure 2. Copies of the test pit logs are included in
Appendix A.
213 County Road 228
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06/17/25
V:\2008 ALL PROJECTS\03019 - Kyle Byman\03019-0001 213 County Road 228\200 - Geo\03019-0001 OWTS061625.doc 2
Onsite Wastewater Treatment System
As discussed previously, Soil Type 2 and Soil Type 2A were identified at the site. In order to
use a higher Long-Term Acceptance Rate (LTAR), this design requires the Soil Treatment
Area (STA) trenches be no deeper than 2.0 feet below existing grade at this site. Failure to
adhere to this recommendation would result in a reduced LTAR and a larger STA.
Seepage Bed Design
The design of the absorption system generally follows the requirements of the Garfield County
Department of Public Works as outlined in the Garfield County On-Site Wastewater Treatment
System Regulations, effective June 2018. The proposed construction at the site is anticipated to
include a four-bedroom home. The existing system uses serial distribution and it is assumed
additional trenches will be added to the existing STA to accommodate the new design effluent
flows.
Based upon the visual tactile classification of the soils, a Long-Term Acceptance Rate (LTAR)
of 0.6 will be utilized for the absorption field design. Infiltrator Systems Quick4 Standard
Chambers are proposed. The daily flow of the sewage disposal system is calculated below and a
plan and profile of the absorption system are shown on Figure 3.
Average Daily Flow = (7 persons)(75 GPD/person)
= 525 GPD
Soil Treatment Area = (525 GPD / 0.6) = 875 Square Feet
Adjusted Soil Treatment Area = (875 SF)(1.0)(0.7) = 613 Square Feet
# of Quick4 Chambers = (613 / 12) = 52 Chambers
# of Existing Chambers = 40 Chambers
Therefore, add 20 new Chambers
System Installation
The installation of the septic tank, plumbing lines, Infiltrators, etc. should be completed in
accordance with Garfield County regulations and Infiltrator Systems, Inc. specifications. In
addition, the following construction procedures are recommended:
The septic tank and distribution box should be placed level over native soils that have
been scarified to a depth of 8 to 12 inches, moisture conditioned, and recompacted to
a minimum of 95% of the standard Proctor maximum dry density, within ±2% of
optimum moisture content. However, up to 3-inches of washed rock or pipe bedding
passing the 1-inch sieve may be used as a leveling course under the septic tank and/or
distribution box.
The bottoms of trenches and backfill around the septic tank and distribution box
which will support sewer or effluent lines should be compacted to at least 90 percent
of the standard Proctor maximum dry density, within ±2% of optimum moisture
content. Pipe bedding should have a maximum particle size of 1-inch.
Vehicular or heavy equipment traffic and placement of structures should not encroach
within 10 feet of the septic tank or distribution box.
213 County Road 228
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06/17/25
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Inspection Schedule
Huddleston-Berry Engineering & Testing LLC should be retained to monitor the construction of
the OWTS. The following schedule of observation and/or testing should be followed:
Observe the absorption bed excavation prior to placement of Infiltrator chambers.
Observe placement of the septic tank, distribution box, and all connecting sewer and
effluent lines prior to backfill. Verify proper fall between inverts.
Observe and verify installation of the absorption bed prior to placement of cover and
backfill.
In conformance with Garfield County regulations, HBET will be required to provide the Garfield
County Health Department with documentation certifying that the OWTS was placed in
conformance to the plan and profile and Garfield County regulations.
General Notes
The OWTS design was based upon the results of the subsurface investigation and on our local
experience. The design is valid only for the proposed construction.
We are pleased to be of service to your project. Please contact us if you have any questions or
comments regarding the contents of this report.
Respectfully Submitted:
Huddleston-Berry Engineering and Testing, LLC
Wayne D. Anderson, P.E.
Project Engineer
FIGURES
Gar eld County, CO
Developed by
Date created: 4/21/2025
Last Data Uploaded: 4/21/2025 2:06:41 AM
971 ft
2789 Riverside Parkway
Grand Junction, CO 81501
Project No.: 03019-0001
Date: 06/17/25
By: WDA
213 COUNTY ROAD 228
PARCEL#212531300140
FIGURE 2 - SITE PLANTEST PIT
C.I. = 2 FT
SCALE: 1" = 200'
**NOTE:TANK AND BED LOCATIONS APPROXIMATE AND MAY SHIFT SOME DURING
CONSTRUCTION BASED UPON SITE TOPOGRAPHY, OWNER PREFERENCE, AND/OR OTHER
FACTORS AS LONG AS APPLICABLE SETBACKS ARE MET. ACTUAL LOCATION OF TANK AND
BED WILL BE INDICATED ON AS-BUILT DRAWINGS.**
SITE PLAN
ENLARGED VIEW
TP-1 TP-2
~68'
~900'
~150'
~595'
~370'
~550'
TP-1
5748
TP-2
5746
5744
5742
5740
5738
5750
12'
(10' MIN)
40'
40'
6' MIN
6' MIN
60'
~43'98'
38'
25'
~39'
~33'
~14'
SCALE: 1" = 40'
NEW HOME
EXISTING 1,250 GALLON
TANK - VERIFY 2 CHAMBERS
EXISTING HOME
STA
NEW
HOME
EXISTING HOME -
TO BE REMOVED
**APPROXIMATE LOCATION
OF EXISTING STA
NEW STA TRENCHES
REPAIR
AREA
EXISTING SHED
EXISTING PUMP HOUSE
EXISTING WATER LINE - TO BE ABANDONED/REMOVED
** ASSUMED NEW WATER LINE LOCATION
ENLARGED VIEW BOUNDARY
ENLARGED VIEW BOUNDARY
NEW CONCRETE
2789 Riverside Parkway
Grand Junction, CO 81501
Project No.: 03019-0001
Date: 06/17/25
By: WDA
MINIMUM SETBACKS
(UNITS = FT)
**OTHER SETBACKS NOT LISTED HERE SHOULD BE IN ACCORDANCE WITH GARFIELD COUNTY OWTS REGULATIONS
**USE SWEEP 90'S OR
TWO 45'S AT 90
DEGREE BENDS**
DETAIL AREA
SCALE: 1" = 30'
213 COUNTY ROAD 228
PARCEL#212531300140
FIGURE 3 - SEPTIC SYSTEM
DETAILS
WATER LINE
4-INCH DIAMETER SEWER AND EFFLUENT PIPE
MEETING ASTM D1785, SCHEDULE 40 OR SDR 35
ENCASED IN 8-INCH SCHEDULE 80 ALONG
SEGMENT LESS THAN 25 FEET FROM WATER
LINE
EXISTING SEPTIC TANK WITH
MINIMUM 1,250 GALLON
CAPACITY
NEW HOME
INSPECTION PORTS
2 TRENCHES WITH 10 QUICK4
STANDARD INFILTRATORS OR
ENGINEER APPROVED EQUAL
PER TRENCH
GENERALIZED SYSTEM PROFILE
GENERALIZED BED PROFILE
INFILTRATOR SYSTEMS QUICK4
STANDARD CHAMBERS
NONWOVEN, NEEDLE PUNCHED, GEOTEXTILE
FABRIC IMMEDIATELY ABOVE CHAMBERS
COVER SOIL; NATIVE SOILS OR OTHER SUITABLE
TOPSOIL. GRADE TO CARRY SURFACE WATER
AWAY FROM BED.
INSTALL ROWS OF INFILTRATORS IN
LEVEL TRENCHES FOLLOWING GROUND
CONTOURS
6 FT MIN BETWEEN TRENCHES28'-314"
2 COMPARTMENT SEPTIC
TANK FROM CDPHE
APPROVED TANK LIST
40'
6' MIN
~33'
~39'
3'
EXISTING TRENCHES
**2.0 FEET MAX BELOW
EXISTING GRADE
APPENDIX A
Typed Test Pit Logs
Sandy Loam with Organics (TOPSOIL)
Sandy Loam with Gravel, reddish-tan, moist, medium stiff,
moderate granular structure (Soil Type 2 < 35% Rock)
Silty Loam with Gravel, reddish-tan, moist, medium stiff, weak
granular structure (Soil Type 2A < 35% Rock)
Bottom of test pit at 8.0 feet.
NOTES
GROUND ELEVATION
LOGGED BY TC
EXCAVATION METHOD Trackh/Backhoe AT TIME OF EXCAVATION Dry
AT END OF EXCAVATION Dry
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR Client GROUND WATER LEVELS:
CHECKED BY MAB
DATE STARTED 4/21/25 COMPLETED 4/21/25
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
GR
A
P
H
I
C
LO
G
ATTERBERG
LIMITS
MATERIAL DESCRIPTION
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
FI
N
E
S
C
O
N
T
E
N
T
(%
)
RE
C
O
V
E
R
Y
%
(R
Q
D
)
BL
O
W
CO
U
N
T
S
(N
V
A
L
U
E
)
PO
C
K
E
T
P
E
N
.
(t
s
f
)
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
LI
Q
U
I
D
LI
M
I
T
PL
A
S
T
I
C
LI
M
I
T
PL
A
S
T
I
C
I
T
Y
IN
D
E
X
PL
A
S
T
I
C
I
T
Y
IN
D
E
X
PAGE 1 OF 1
TEST PIT NUMBER TP-1
CLIENT Kyle Byman
PROJECT NUMBER 03019-0001
PROJECT NAME 213 County Road 228
PROJECT LOCATION Silt, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
0
3
0
1
9
-
0
0
1
9
2
1
3
C
O
U
N
T
Y
R
O
A
D
2
2
8
.
G
P
J
G
I
N
T
U
S
L
A
B
.
G
D
T
5
/
2
/
2
5
Huddleston-Berry Engineering & Testing, LLC
2789 Riverside Parkway
Grand Junction, CO 81501
970-255-8005
Sandy Loam with Organics (TOPSOIL)
Sandy Loam with Gravel, reddish-tan, moist, medium stiff,
moderate granular structure (Soil Type 2 < 35% Rock)
Silty Loam with Gravel, reddish-tan, moist, medium stiff, weak
granular structure (Soil Type 2A < 35% Rock)
Bottom of test pit at 8.0 feet.
NOTES
GROUND ELEVATION
LOGGED BY TC
EXCAVATION METHOD Trackh/Backhoe AT TIME OF EXCAVATION Dry
AT END OF EXCAVATION Dry
AFTER EXCAVATION ---
TEST PIT SIZE
EXCAVATION CONTRACTOR Client GROUND WATER LEVELS:
CHECKED BY MAB
DATE STARTED 4/21/25 COMPLETED 4/21/25
DE
P
T
H
(f
t
)
0.0
2.5
5.0
7.5
GR
A
P
H
I
C
LO
G
ATTERBERG
LIMITS
MATERIAL DESCRIPTION
SA
M
P
L
E
T
Y
P
E
NU
M
B
E
R
FI
N
E
S
C
O
N
T
E
N
T
(%
)
RE
C
O
V
E
R
Y
%
(R
Q
D
)
BL
O
W
CO
U
N
T
S
(N
V
A
L
U
E
)
PO
C
K
E
T
P
E
N
.
(t
s
f
)
DR
Y
U
N
I
T
W
T
.
(p
c
f
)
MO
I
S
T
U
R
E
CO
N
T
E
N
T
(
%
)
LI
Q
U
I
D
LI
M
I
T
PL
A
S
T
I
C
LI
M
I
T
PL
A
S
T
I
C
I
T
Y
IN
D
E
X
PL
A
S
T
I
C
I
T
Y
IN
D
E
X
PAGE 1 OF 1
TEST PIT NUMBER TP-2
CLIENT Kyle Byman
PROJECT NUMBER 03019-0001
PROJECT NAME 213 County Road 228
PROJECT LOCATION Silt, CO
GE
O
T
E
C
H
B
H
C
O
L
U
M
N
S
0
3
0
1
9
-
0
0
1
9
2
1
3
C
O
U
N
T
Y
R
O
A
D
2
2
8
.
G
P
J
G
I
N
T
U
S
L
A
B
.
G
D
T
5
/
2
/
2
5
Huddleston-Berry Engineering & Testing, LLC
2789 Riverside Parkway
Grand Junction, CO 81501
970-255-8005