HomeMy WebLinkAboutEngineer's OWTS Design PlanHuddleston-Berry
Engineering & Testing, LLC
July 25,2025
Project#03030-000 1
Mountain Homestead Construction LLC
POBox2637
Meeker, Colorado 81641
Attention: Mr. Brady Stallings
Subject OWTS Design
2027 County Road 245
New Castle, Colorado
Reference:Geotechnical Investigation, 2027 County Road 245, New Castle, Colorado by
Huddleston-Berq, Engineering & Testing, LLC for Brady Stallings, June 12,
2025.
Dear Mr. Stallings,
At your request, Huddleston-Berry Engineering & Testing, LLC completed design of an Onsite
Wastewater Treatment System (OWTS) for a new Accessory Dwelling Unit (ADU) at 2027
County Road 245 in New Castle, Colorado. The site location is shown on Figure I - Site
Location Map. A site plan is included as Figure 2.
Site Description
At the time of the investigation, the western portion of the site was occupied by an existing
residence and Elk Creek. The remainder of the site was open and generally sloping down to the
southwest. Site topography is shown on Figure 2. Vegetation at the site primarily consisted of
weeds, grasses, and sparse trees. The site was bordered to the north and east by County Road
245, and to the west and south by rural residential/agricultural properties.
Subsurface Investigation
As discussed in the referenced report, the subsurface conditions at the site were slightly variable.
However, using visual-tactile classification methods, the soil profile in the vicinity of the
proposed Soil Treatment Area (STA), consisted of 1.0 foot of topsoil above brown, moist, stiff
silty clay loam soils with a moderate blocky structure that extended to the bottoms of the
excavations. The site soils are consistent with Soil Type 3.
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.
2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlestonberry.com
The locations of the test pits are shown on Figure 2. Copies of the test pit logs are included in
Appendix A.
2027 County Road 245
#03030-000r
07/25/25
Onsite Wastewater Treatment System
,A\
@ Huddleston-Berry
EilSinccring& I.illng, l-t.C
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 Regulotions, effective June 2018. The proposed construction at the site is anticipated to
include a two-bedroom ADU.
Based upon the visual tactile classification of the soils, a Long-Term Acceptance Rate (LTAR)
of 0.35 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: (4 persons)(75 GPD/person)
:3OO GPD
Soil Treatment Area: (300 GPD I 0.35):857 Square Feet
Adjusted Soil Treatment Area : (857 SFX1 .2)(0.7):720 Square Feet
# of Quick4 Chambers: (720 I 12):60 Chambersl Use 64 Chambers
System Installation
The installation of the septic tank, plumbing lines, Infiltrators, etc. should be completed in
accordance with the Garfield County On-Site Wastewater Treatment System 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 95o/o of the standard Proctor maximum dry density, within +2o/o 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.r 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 +2Yo 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 l0 feet of the septic tank or distribution box.
Inspection Schedule
Huddleston-Berry Engineering & Testing LLC should be retained to monitor the construction of
the OWTS. The following schedule of observation andlor testing should be followed:I Observe the absorption bed excavation prior to placement of Infiltrator chambers.r Observe placement of the septic tank, distribution box, and all connecting sewer and
effluent lines prior to backfill. Verifu proper fall between inverts.. Observe and veriff installation of the absorption bed prior to placement of cover and
backfill.
2V:\2008 ALL PROJECTS\o3010 - Mountain Homestead Construction LLC\03030-0001 2027 County Road 245\200 - Geo\03030-0001 OWTS070325 doc
2027 CounIykoad24l
#03030-0001
07/25125
A@ Huddleston-Berry
Englnccrina& T.{lnt, Ll.C
In conformance with Garfield County regulations, HBET will be required to provide the Garfield
County Health Department with documentation certi$ing 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
JV:V008 ALL PROJECTS\03030 - Mountain Homestead Construction LLC\03030-0001 2027 County Road 245\200 - Geo\03030-0001 OWTS070325.doc
FIGURES
G)qPublic.net'" Garfi eld County, CO
Date created: 5/6/2025
Last Data Uploaded: 5/6/2025 2:12:44 AM
FIGURE 1
Site Location Map
Develoned bvfl SCH N EI DER
GEO9PATIAL
APPENDIX A
Typed Test Pit Logs
GEOTECH BH COLUMNS 03030-0001 2027 ROAD 245 - OWTS.GPJ GINT US LAB.GDT 7ND5
!voL.
mo-{zc
=@
mF
o
(J)oo)oooo
otr
mz-{
ocf
o).
Io
3o
rn
o
n,
CL
oofa
co
6'J
t-t-o
\O A NJ rrr{:'{ =oN 6=
a^:-f,6-qlr'@
oo5 d oagt ?
Lro ow500J !=
O o'Q
2=6<oa
I.
0q
F
-lo
Ec--o
!noC-
mo-{t-oo{oz
zo€o
0)I
!D
oo
!vo(-
mo-{z
=m
N)oN-.1
ooc
f
vo
A'o
tus(n
{ma{!+zc
=tD
rTln
{!IN
T]
om
o"Tt
zo-{m
@
t-ooo
mI
ID
-lc)
mxo
=oz
=m-{Ioo
-{qt
oxJ
@qt
c)x5oo
mxo
Iozooz
7
o-{on
o
o
o
-{m
(n
-{,{
mI
(,r
-{
N(t
oI
mox
m0
@
(D
oo3!t-mI
m0
(t
-.t
N(t
ono
tP==m:m:lxY9*
SExu
dEin
r96tzz.
onoczo
mt-m
=oz
Ia g
a
-{m
CN-{!-{
9,Nm
Po DEPTH
(ft)
GRAPHIC
LOG
-lmn
Ft-
o
ma
c)v
T'-loz
SAMPLE TYPE
NUMBER
RECOVERY %
(ROD)
BLOW
COUNTS
(N VALUE)
POCKET PEN.
(ts0
DRY UNITWT
(pc0
MOISTURE
CoNTENT (%)
-lr-l
=m<'7
-l@@mno
FINES CONTENT
(%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
!to
r<,1! ;i |j
@
os
1-o
ot
3
5.
o
(o
q)
foo
--lo!
@It-
Gqe.€
-ro*<d
6'<e5q'
-3F
o{
-f
3o
a5+
o
-+
3o
CLo
0)
o
6
oox
o
co
c
d
f(t
(Do
o
3
o
oa
:o
0)
@b
(Do
a+
GEOTECH BH COLUMNS O3O3O-OOO1 2027 COUNry ROAD 245 - OWTS-GPJ GINT 7nt25
!vo(-
mo-tzc
=TD
m7
o(,o
CJo
ooo
otr
mzI
ocf
9.
Io
3oo
o[)o-
ff
s^N)trr{ i'-l FoD *=
q-'''i.
6= d oag; ?
uo ow500' +q
vfgr
6-.<dCcE i'
0q
R"rto-
sc
t.l-o
t-r-o
!uo(-
mo-l
t-oo
-{6z
zo
€
c)
o)a
=!D
oo
!uo(-
mo-{z
=m
N)oN-.t
ooEf
no
o)o-
t\)s(,|
I
m
@+
!
{zc
=TDmv
{!I(.t
T'
o
m
o-Tt
zo-{m(t,
FlnoxooODg;
E+<2
-{=c)m-{Lotr'
mxo
=ozooz
-.17
o{ov
o
o
=
tr
-{ma-{
v{
mg
ol
-.t
N(Jr
oI
moxm0
ID
ID
-l
0)o-J
IDq)oxfoo oo
=!rm-{m0
('r
_.1
N(Jl
ono
r2==
SHHM
iEHgeiEh
r06'zz
oFoczq
mt-m
-{oz
o
?o
a
-{ma{
!-{
9,Nm
Io DEPTH
(ft)
GRAPHIC
LOG
-lm7
t-o
m
@ov
l,Ioz
SAMPLE ryPE
NUMBER
RECOVERY %
(ROD)
BLOW
COUNTS
(N VALUE)
POCKET PEN
(ts0
DRY UNIT WT
(pcf)
MOISTURE
CoNTENT (%)
+r -'{
=mSF
-l tDu)mno
FINES CONTENT
(%)
LIQUID
LIMIT
PLASTIC
LIMIT
PLASTICITY
INDEX
Nit
ia:,ri ;: 13
@
oo
t-o
0t
3
g.
=o
(cI
!)
6'a
-toT'
@o
t-
Gq.9€-lo.<d
6.<I,5
A)
-3o
o€
-3
3o6
o
-+
3oo-oil
o
o-oX
a
co
c
o
IDo
o
3
o
oa
E
0)
@b
ooi+