HomeMy WebLinkAboutEngineer's OWTS Design PlanProposed Onsite Wastewater Treatment System Design
s-BR Single-Family Residence &
2-BR Accessory Dwelling Unit
TBD Colorado River Road
New Castle, CO 81647
Parcel No. 218L-072-03-009
Prepared for:
Vanessa Evenden
July, 2025
Prepared by:
tegr:ng
2516 Foresight Circle #1, Grand Junction, CO 81505 Telephone: (970)241-7076
1.0 SCOPE
This report presents the findings of an On-Site Wastewater Treatment System (OWTS) design
for a proposed five-bedroom (5-BR) single-family residence and two-bedroom (2-BR) Accessory
Dwelling Unit (ADU) at TBD Colorado River Road (Parcel No. 218l-072-03-009) in New
Castle, Colorado. The purpose of this report was to establish design criteria for a new OWTS
system. The report includes an assessment of observed subsoil and groundwater conditions,
percolation test results, and the design and construction parameters for the OWTS. The findings
are based on data gathered from field percolation testing and engineering evaluation based on
experience with similar site conditions.
2.0 DESIGN SUMMARY
1. Encountered subsurface conditions in the test pits consisted of 1 foot of topsoil
underlain by gravelly sand with cobbles (<35% rock) to the maximum depth explored
of 8 feet below ground surface (Appendix A for visual and tactile evaluation).
Groundwater was not encountered at the time of observation to 8 feet below ground
surface.
2. The percolation result at the elevation of infiltration was 9.9 minutes per inch. We
determined from Table 10-l of Garfield County's On-Site Wastewater Treatment
System Regulation (Regulations) that the treatment area soil type is Type I and used
"Long Term Acceptance Rate" (LTAR) :0.8 gallons per day per square foot.
3. The design system will utilize two new CDPHE approved septic tanks; one 1,500
gallon tank servicing the 5-BR dwelling and one 1,000 gallon tank servicing the 2-BR
ADU. Both tanks will jointly discharge effluent to four (4) new Quick 4 Plus
Infiltrator trenches, each with seventeen (17) units, for a total minimum disturbed
area of about24 feet by 7l feet, including 4 feet separation distance between trenches
and chamber end caps.
requirements,
which must be confirmed prior to installation by the licensed installation contractor
3.0 EXISTING SITE CONDITIONS
The 7.}9-acre parcel located at TBD Colorado River Road was a barren lot with an irrigation
pond as well as a steep bluff which separated the buildable area of the lot from the adjacent
Colorado River. In the vicinity of the new construction, the lot slope down to the northwest at
approximately 2o/o.
4.0 PROPOSED SITE IMPROVEMENTS
A proposed 5-BR single-family residence and 2-BR ADU are to be constructed. The structures
will have no below grade/basement areas. If the proposed construction is different than what is
described above, WestWater Engineering should be notified to re-evaluate the recommendations
made herein.
The new 5-BR dwelling will be served by a new 1,50O-gallon septic tank (minimum) while the
2-BR ADU will be served by a new 1,000-gallon septic tank (minimum). The structures will
jointly discharge to a total of 68 new Standard Plus Quick4 Infiltrator@ units configured in four
(4) trenches, eachwith seventeen (17) Q4 Plus units for a minimum 24' x7l' footprint including
4 feet separation distance between trenches and chamber end caps (Figure B2).
5.0 SOIL INVESTIGATION
WestWater Engineering collected soil and percolation data on April22,2025,in accordance with
the Regulations. The soil profile in the vicinity of the proposed Soil Treatment Area (STA)
shows topsoil 1 foot below ground surface underlain by gravelly sand with cobbles to the
maximum depth explored of 8 feet below ground surface. No groundwater was encountered at
the time of observation (Appendix A).
Percolation rates ranged from 11.1 to 8.7 minutes per inch (Appendix A). WestWater
Engineering finds the average percolation rate of 9.9 minutes per inch to be most applicable.
Based on the Garfield County, On-Site Wastewater Treatment System Regulations effective
Apri120,2023, Table 10-1, the soil type was determined as Soil Type l, Long Term Acceptance
Rate (LTAR) :0.8 gallons per day per square foot, which most nearly describes the condition
for this site and proposed construction.
6.0 OWTS w DE,SIGN FLOW
As per guidelines, the occupancy is twelve (12) persons, tabulated as 2 people per bedroom for
the first 3 bedrooms of both structures and one additional person for every additional bedroom
beyond the first three in each structure. The design flow is twelve (12) persons x 75 gallons per
day per person : 900 gallons per day.
7.0 OWTS DESIGN
Septic Tank
The minimum septic tank capacity required to service a total of five (5) and two (2) bedrooms
are 1,500 gallons and 1,000 gallons respectively in accordance with Table 9-l of the
Regulations. The minimum required septic tank volumes will provide a 48-hour (2-day) particle
detention time for the wastewater flow capacity of the proposed OWTS. The required capacities
of 1,500 and 1,000 gallons individually exceed their respective estimated daily wastewater flow
of 600 and 300 gallons per day (GPD) over a two-day period (600 GPD x 2 days :1,200
gallons. 300 GPD x 2 days: 600 gallons), ensuring compliance with the Regulations. The tanks
shall be equipped with locking or secured access lids to prevent unintended access, as well as an
effluent screen (or filter) at the tank outlets.
Furthermore, the proposed septic tanks for the OWTS shall be selected from the current
Colorado Department of Public Health and Environment (CDPHE) approved septic tank list.
Page2
Distribution Box
For this design, use a new distribution box (D-box) approved for use in Garfield County. Ensure
that the flow is equal between laterals by using flow equalizers in the D-box, and access is
available for maintenance and inspection via an approved riser assembly with a locking lid.
Soil Treatment Area (STA)
Gravelly sand occurring at the 4.0-foot depth interval will be used for the upper infiltrative
surface for the proposed STA (Figure B3). Maximum trench depth must not exceed 4 feet in
accordance with the Regulations. Trench excavation will remove approximately 4.0 feet of soil
and upper root mass to prepare the level surface for installing infiltrators on the receiving soil
infiltrative surface, providing secondary treatment of discharged wastewater. Soil should not be
wet at the time of excavation. Soil covering the STA must be crowned over proposed trenches or
match the existing grade so water runs off and is not ponded over any area of the STA. Prior to
backfilling the final soil cover, a pervious soil barrier of non-woven geotextile fabric (2 ozlyd2
minimum) or similar pervious material shall be installed over the STA to prohibit soil intrusion
(See Figure B3 - OWTS Cross Section). All setback distances per the Regulations apply to
septic system installation.
The following design calculations propose to discharge septic tank effluent to four (a) Quick4
Plus Infiltrator trenches, each with seventeen (17) units, for a total minimum disturbed area of
about 24 feetby 7l feet, including 4 feet separation distance between trenches and chamber end
caps. A total of 68 Quick 4 Standard Plus Infiltrator units will be installed in the four-trench
configuration, which is generally oriented northeast and southwest. It should be noted that other
manufacturers of infiltrators can be used, but the use of alternative system components will
require verification by the Engineer to determine conformance with design requirements for this
system.
Desian FlowSTA: L.AR x Method x Media (1)
Where:
STA:
Design Flow:
LTAR:
Method:
Media:
Total surface area required to effectively discharge sewage effluent
Estimated volume of wastewater per day
Long-Term Acceptance Rate of soil treatment area
Method of effluent application and type of soil treatment area
Type of distribution media
Page 3
STATotalchambers: m.(2)
Where:
Chamber Area:The County and State approved bottom chamber area for Quick 4 Plus
Standard Infiltrator lJnit,12 ff
If,
Per Regulations Table 6-1,
5-BR Flow: 600 Gallons/Day
2-BR Flow: 300 Gallons/Day
Therefore,
Design Flow : 900 Gallons/Day
Long Term Acceptance Rate (LTAR) review of Regulations Table 10-1,
LTAR : 0.8 Gallons/DaylFoot2
The type of application for this system is a gravity-fed trench system, per Regulations Table l0-
)
Method: 1.0
Distribution media is chosen as chambers, per Regulation Table l0-3,
Media:0.7
Then,
900STA= 0S "1.0 x0.7
The minimum STA Area is 757.5 ff.
(1)
(2)787.5Total Chambers :n
The minimum number of Quick 4 Plus Infiltrators is 65.6. As 65.6Infiltrators cannot be evenly
divided between four trenches to ensure equal effluent flow, the design increases the number of
Quick 4 Plus Infiltrators to a total of 68, divided between four trenches with seventeen (17) units
each.
Page 4
8.0 SYSTEMINSTALLATIONREOUIREMENTS
The installer should confirm the feasibility of gravity discharge of sewage effluent from the
proposed residence to the STA. If field measurements do not confirm the design assumptions for
gravity discharge of sewage effluent from the proposed residence to the STA, or if the installer
does not consider the above design assumptions practical, please contact the design engineer to
address any design modifications necessary for the effective operation of the OWTS.
The installer must also confirm all setbacks from property lines, building envelopes, and existing
easements are maintained. Additionally, any unknown utility lines, easements, or other adverse
conditions disclosed during construction must maintain at the required minimum setbacks.
All sewer pipe couplings must be completed with primed and glued or bell and spigot joints
using 4-inch SDR 35 PVC pipe. Schedule 40 PVC 4-inch pipe with a minimum 1-foot soil cover
must be used if pipe is installed in a vehicular traffic crossing. Drain-waste-vent (DWV) rated
Schedule 40 PVC pipe is called out for crossings but may also be used instead of SDR 35 PVC
pipe.
Building sewer pipe must be installed at a slope between %-inch andl+-inch per foot slope (l to
2o/o), preferably using the %-inch per foot slope as recommended by the Intemational Plumbing
Code (IPC) as administered by the County. Fittings shall be sweep 9O-degree curves or two (2)
45-degree elbows at all influent pipe turns. Fittings must be DWV for schedule 40 PVC pipe.
Two-way clean-outs are required between dwelling and tank and beyond tank where pipe lengths
exceed 100-feet from tank to STA and at all pipe bends greater than 45 degrees. Clean outs shall
be installed with screw caps at finished grade with a protective housing for easy access by
homeowner
The installer must adhere to the minimum and maximum depth requirements for the STA.
System components must be placed on native soils or re-stabilized soils, as specified by the
engineered OWTS reports, in excavated areas.
The owner will ultimately be responsible for septic system maintenance including pumping the
septic tank once every 2-3 years and cleaning the effluent filter every 6 months.
9.0 SYSTEM INSPECTION
WestWater Engineering is responsible for inspecting the OWTS to ensure construction conforms
to the design plan and meets all aspects of County Regulations, including:
o Inspect and measure the system before backfilling, including piping and septic system
components.
. Complete the as-built drawing of the system and submit it to Garfield County for
approval.
o Reviewing and approving any submitted changes necessary for installation of the OWTS
as deemed necessary by the owner or their contractor. Any system changes installed by
Page 5
the owner/contractor that were not approved by the Engineer are the responsibility of the
owner.
1O.O DESIGNLIMITATIONS
The OWTS design is based on site-specific soil conditions and percolation data collected in the
vicinity of the proposed STA, as well as local experience in designing OWTSs in Colorado. The
design is only valid for the proposed new OWTS serving the proposed 5-BR dwelling at the
referenced location provided in this report. WestWater Engineering assumes no liability for
inaccurate information or conditions that vary from the design assumptions listed above.
Additionally, WestWater Engineering is not responsible for the quality of work for any person(s)
or entity performing or supporting construction activities relating to the project, or for any
contractor's failure to furnish or perform its work in accordance with the plans, specifications or
the Regulations. The owner/contractor is to notiff WestWater Engineering and/or Garfield
County immediately if actual site conditions differ from those described herein.
Please do not hesitate to contact us if you have any questions regarding this report.
Page 6
APPENDIX A
SOIS AND PERCOLATION DATA
Q\Nest Water En g i neering
e consutting rngineers & Scientiits
251 6 FORESIGHT CIRCLE, #'I GRAND JUNCTION, COIORADO 8T5O5 t970l 241-7076 - FAX (97O) 241-7097
SOILS AND PERCOLATION REPORT
Date:July 17,2025
Consultant:Curtis Beckel, EIT
WestWater Engineering
2516 Foresight Circle #1
Grand Junction, CO 81505
(970) 24r-7076
Client:Vanessa Evenden
Land Parcel: TBD Colorado River Road, New Castle, CO 81647
2l8t-072-03-009
SECTIONl-SOILSLOG
Two test pits were evaluated at the empty 7.}9-acre parcel for an onsite wastewater treatment
system (OWTS) that will serve a new proposed 5-BR single-family dwelling and new proposed
2-BR Accessory Dwelling Unit located at TBD Colorado River Road, New Castle, Colorado.
The first Test Pit (TP-l) was located approximately 90 feet south of the north property line and
l7 feet east of the west property line (see Figure B1 of the Design Report). The second Test Pit
(TP-2) was located approximately south of the north property line and feet ease of the west
property lie. The benched test pits were in general conformance with Figure A1 with a maximum
depth of8 feet (96 inches) below ground surface.
The visual description of the profile soils, with ASTM D 2488 "Standard Practice for
Description and Identification of Soils (Visual-Manual Procedures)" used for guidance, is
summarized below and in Table I - Log of Exploratory Test Pits. ASTM D 2488 identifies soils
based on visual examination and manual tests.
A1
Table L - Log of Exploratory Test Pit 1
TBD Colorado River Road
New Castle, Colorado
Test Pit I
Location: See Figure B-1 Date:4-22-25
Depth
(f0 Description Interval
(f0 Notes
0 Stiff, dry, tan and grey, low plasticity, silty CLAY 0-1 Topsoil
Dense, dry, grey and brown, gravelly SAND with
cobble (Alluvium)
Total Depth: 8 feet below ground surface
1-8
5
A2
TBD Colorado River Road
New Castle, Colorado
Test Pit 2
Location: See Figure B-1 Date:4-22-25
Depth
(f0 Description Interval
(f0 Notes
0 Stiff, dry, tan and grey, low plasticity, silty CLAY 0-l Topsoil
Dense, dry, grey and brown, gravelly SAND with
cobble (Alluvium)
Total Depth : 8 feet below ground surface
1-8
5
Table 2 -Log of Exploratory Test Pit 2
Subsurface conditions encountered in the test pits consisted of one foot of silty clay topsoil
underlain by gravelly sand to the maximum depth explored of 8 feet below ground surface. The
silty clay topsoil was stiff, dry,tan and grey. The gravelly sand was dense, dry, grey and brown
with maximum grain size nearing 3-inch (cobble) indicative of Alluvium deposit (<35% rock).
No groundwater was encountered at the time of observation.
A3
SECTION 2 _ PERCOLATION TEST
Four standard percolation rate tests were performed at the site referenced.
TP-l and TP-2 each contained 2 percolation test holes, approximately I foot in depth each,
herein referred to as P-l thru P-4. P'l was located in TP-l at2 feet below ground surface
gravelly sand. P-2 was located in TP-l at 4 feet below ground surface in gravelly sand. P-3 was
located in TP-2 at2 feet below ground surface in gravelly sand. P-4 was located in TP-2 at 4 feet
below ground surface in gravelly sand. All percolation holes were saturated 24 hours before
testing.
The percolation rates encountered ranged from to min/in. WestWater Engineering finds the
average percolation rate of 9.2 most nearly describes the behavior of the soils at the expected
infiltration elevation of 3 feet below ground surface.
A4
PERCOLATION TEST RESULTS
TBD Colorado River Road, New Castle
SATURATION AND PREPARATION
DATE: 4-21-25
PERCOLATION TEST
DATE: 4-22-25
HOLE REFERENCE NO: P-l
PERC HOLE DEPTH: 2feet
TIME INTERVALS: l0 minutes
AVERAGE PERCOLATION RATE (MIN/INCH)11.1
TIME AT
START OF
INTERVAL
START OF
INTERVAL
(rNCrr)
END OF
INTERVAL
(rNCrI)
WATER
DEPTH
CHAi\GE
(rNCrr)
PERCOLATION
RATE
(MrN/rNCrI)
1 130 t0 0 1.5 1.5
I 140 10 1.5 2.75 t.25
1 150 10 2.75 4 1.25
t200 10 0 I I
r2t0 10 I 2 I
t220 10 2 J 1
t230 t0 J 3.75 0.75
1240 10 3.7s 4.5 0.75
1250 10 0 0.75 0.75
1300 10 0.75 1.5 0.75
13 10 l0 1.5 2,2s 0.75
1320 l0 2.25 J 0.7s
A5
HOLE REFERENCE NO: P-2
PERC HOLE DEPTH: 4feet
TIME INTERVALS: 10 minutes
TIME AT
START OF
INTERVAL
START OF
INTERVAL
(rNCrr)
END OF
INTERVAL
(TNCII)
WATER
DEPTH
CHANGE
(rNCrr)
PERCOLATION
RATE
(MrN/rNCH)
1 130 0 1.5 1.5 6.67
1140 1.5 J 1.5 6.67
1 150 J 4.2s 1.25 8
1200 4.25 5.25 1 10
I2IO 0 ,|
1 10
1220 1 2 1 10
r230 2 J I t0
t240 J 3.75 0.75 13.33
t250 3.75 4.5 0.75 13.33
1300 0 0.7s 0.75 13.33
13 10 0.75 1.5 0.75 13.33
r320 1.5 2.25 0.7s 13.33
AVERAGE PERCOLATTON RATE (MIN/INCH)10.7
A6
HOLE REFERENCE NO: P-3
PERC HOLE DEPTH: 2feet
TIME INTERVALS: 10 minutes
TIME AT
START OF
INTERVAL
START OF
INTERVAL
(rNCrr)
END OF
INTERVAL
(rNcrr)
WATER
DEPTH
CHAIIGE
(rNCH)
PERCOLATION
RATE
(MrN/rNCH)
1 130 0 1.5 1.5 6.66
1140 1.5 J 1.5 6.66
I 1s0 4.25 1.2s 8
1200 4.2s 5.5 1.25 8
I2IO 5.5 6.75 1.25 8
1220 6.75 7.75 1 10
r230 0 I 1 10
1240 1 2 1 l0
1250 2 J I l0
1300 J 4 1 t0
13 10 4 5 I 10
t320 5 6 I t0
AVERAGE PERCOLATION RATE (MIN/INCH)8.9
A7
HOLE REFERENCE NO: P-4
PERC HOLE DEPTH: 4feet
TIME INTERVALS: 10 minutes
TIME AT
START OF
INTERVAL
START OF
INTERVAL
(rNCH)
END OF
INTERVAL
(rNCrr)
WATER
DEPTH
CHANGE
(rNcrr)
PERCOLATION
RATE
(MrN/rNCH)
1 130 0 1.5 1.5 6.66
1 140 1.5 J 1.5 6.66
1 150 J 4.5 1.5 6.66
r200 4.5 5.75 t.25 8
12r0 5.75 7 1.25 8
1220 7 8.25 t.25 8
1230 0 I 1 10
t240 1 2 1 10
t250 2 J 1 10
1300 J 4 1 10
1310 4 5 I 10
r320 5 6 1 i0
AVERAGE PERCOLATION RATE (MIN/INCH)8.7
A8
FIGURE 1
PERCOLATION TEST PIT
Wflstw@ter
Engineering
2516 Foresight Circle, jt1
Grond Junction, C0 81505
(e7o) 241-7076
A
=
SOILS AND PERCOLATION
TEST PIT SCHEMATIC
Profile View
EXISTING GROUND SURFACE HOLE
SURF
15'____+l ,
1 5
8'
Plon View
o
Cylindricol Percolotion
Test Holes 4-8" Diometer
1-Foot Deep
Oll
l
+
15'
15'
Percolotion Test Pit Plon View & Cross Section
Scole 1":10'
o
o
APPENDIX B
FIGURES
ELD
AP
1
APPROXI
ISTI
I
&
RIVER
i.
R I!/E
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2516 Foresight Circle, # I
Grand Junction, CO 81505
(970) 24r-7076
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FIGURE 81
TBD COLORADO RIVER RD
DfiSNNG OWTS SNE PI.AN
\!)/ '
ON POND
USE
I
.' j'
5610
200 100 0
SCALE: 1":2AO'
2AO
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GEnglneering
25 I 6 Foresight Circle, #l
Grand Junction, CO 81505
(970) 241-7076
www. westwaterco. com
FIGURE 82
TBD COLORADO RIVER RD
PROPOSED OWTS I.AY-OI,'T
APPROXIMATE
LINE-'a 7.09
COUNTY GIS,
EXISTING PROPER.TY
ACRES (PER GARFTELD
JULY 2025)
NEW
L,F*._-t,.S
' - 22.5 ..EW.4" 'PVC
OSED NEW ..1,0O0
N SEPTI c TANK
R'
i1
PROPOSED 2-B
DWELLING
NEW 4'' SDR 35. PVC
SEWER SERVICEI
(L:59.3 L.F.i.,S=2%)
PROPOSED NEW
GALLON SEPTIC
I
NEW 2-WAY:
CLEANOUT (TrP)
1,500
TANK
\II
\I APPROXIMATE
PROPOSED DRIVEWAY
', t.
tr
50250 0
SCALE: 1 ":50'
5 a."
APPROXIMATE
LOGATION OF'
OWTS CROSS SECNON
FIGURE 83
n\lestlllhter
€Engineering
2516 Foresight Circle, #l
Grand Junction, CO 81505
(970) 241-7076
\W.westwaterco.com
NEW 10" ROUND IRRIGATION
VALVE BOX AT EACH PORT
MOUNTED FLUSH WITH GROUN PLACE GEOTEXTTLE (2 OZ/yf) OVen TNFTLTRATORS (Typ)
NEW 4,, SCH 40 PVC OBSERVATION
PORT WITH CAP (TYP CROWN BACKFILL OVER TRENCHES
APPROXIMATE EXISTING
o
+
o()
8.0'
68 Q4 INFILTRATORS
(4) TRENCHES
(rz) ururrs EAcH TRENcH
PROVIDE LEVEL SCARIFIED SURFACE
ACROSS LENGTH OF TRENCH(S), NOTIry
ENGiNEER rF TRENCH BOTTOM(S) ARE WEtV GROUNDWATER_
GREATER THAN 8.0'
TRENCH NOTE:
MMIMUM DEPTH 4.0 FEET
MiNIMUM DEPTH 3.0 FEET
INSTALI.ATION NOTES:
1 ) FoLLOW MANUFACTURERS iNSTRUCTION www.infiltrotorsystems.com
2) SCREW PrPE TOp PORT CHAMBER FACEP|-ATE
3) SCREW FACEPT-ATES AND UNrTS TOGETHER
4) INSTALL MONITORING PORTS TRENCH ENDS
SCALE 1"=5'
+.o'4.O'
3.0
+.o'
TOPSOIL
Oz
a
-
JLI
E
1,500 GALLON SEPTIC TANK
FIGURE 84
A\{estVlhter;F Engineering
2516 Foresight Circle, #l
Grand Junction, CO 81505
(970)241-7076
\W.westwaterco.com
NW,I 24,,A ACCESS
HATCHES WrTH LOCKTNG/
SECURE TANK LIDS
FiNISHED GRADE
NATIVE BACKFILL COMPATEDro 95% MSHTO T-99 *.2%oRENCO (OR EOUTVALENT)
4" EFFLUENT FILTEROPTIMUM SOIL MOISTURE
GRAVITY FLOW FROM
s-BR DWELLING +
NEW 4" SCH 40
PVC SEWER LINE
(L:59.J't, S:-2%)
TO STA
NEW 4,' SCH 40
PVC SEWER LINE
NEW 4,, SCH 40
DISTRIBUTION BOX
PVC WYE/TEE
NEW 1,500 GALLON
SEPTIC TANK
NEW 7+" MINUS WASHED ROCK
(8" INcH DEPTH MINIMUM)
o,
N
xHWL 4, AFFv
I'r)
N
x
+
v?
N
1,OOO GALLON SEPNC TANK
FIGURE 85
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25 16 Foresight Circle, #1
Grand Juction, CO 81505
(970) 241-7076
w.westwaterco-com
NEW 24,,A ACCESS
HATCHES WrTH LOCKTNG/
SECURE TANK LIDS
FINISHED GRADE
NATIVE BACKFILL COMPATED
TO 95% MSHTO T-99 X2%oRENCO (OR EQUTVALENT)
4,, EFFLUENT FILTER
OPTIMUM SOIL MOiSTURE
GRAVITY FLOW FROM
2_BR ADU
NEW 4" SCH 40 PVC
SEWER LINE
(L:7s.2't, S:-2%)
TO STA
NEW 4,, SCH 40
PVC SEWER LINE
DISTRIBUTION BOX
NEW 4" SCH 40 PVC WYE/TEE
NEW 1,OOO GALLON SEPTIC TANK
NEW 7+" MINUS WASHED ROCK
(8" INCH DEPTH MINIMUM)
NOTE:
CONTRACTOR IS TO WRIFY SLOPE BET'TEEN SEPTIC TANK PUMP PIPE
CONNECTION AND INFILTMTOR BED CONNECftON TO DETERTIINE IF
SLOPE ADJUSTUENT IS REQUIRED PRIOR TO INSTALUNC FORCE TIAIN.
I
X
+
HWL 4, AFF
r.o
N
v
N
rO
rr)
N
APPENDIX C
GARFIELD COUNTY ON.SITE WASTE WATER
TREATMENT SYSTEM REGULATIONS, TABLE
7.1 FROM THE 2OI9 REGULATIONDOCUMENT
CODE OF COLORADO REGULATION
Water QualiU Control Commission
5 CCR 1002-43
Table 7-1 Minimum Horizontal Distances in Feet Between Components of an On-Site Wastewater Treatment System lnstalled After
November 1 1973 and Water and Health Features
Septic
Tank,
Higher level
treatment
Unit,
Dosing
Tank, Vault
or Privy
5
5
5
10
10
Dry
Gulch,
Cut
Bank,
Fiil
Area
(from
Crest)
10
102
25
50
502
503
25
25
Lake,
Water
Course,
lrrigation
Ditch,
Stream,
Wetland
10
102
25
10
10
Subsurface
Drain,
lntermittent
lrrigation
Lateral,
Drywell,
Stormwater
Structure
102
10
10
10
Property
Lines,
Piped or
Lined
lrrigation
Ditch,
upslope
curtain
drain
10
Structure
without
basement,
crawl
space or
footing
drains
5
0
10
10
15
5
0
20
15
15
Structure
w/basement,
crawl space
or footing
drains
56
252
102
102
Potable
Water
Supply
Line 2
102
502
100 3
60
60
Spring,
Well,1
Suction
Line,
Potable
Water
Supply
Cisterna
502
Building Sewer or
Effluent Lines
STA Trench, STA
Bed, Unlined
Sand Filter, Sub-
surface Dispersal
System, Seepage
Pit
Lined Sand Filter
Lined Evapo-
transpiration Field
or Outside of
Berm of Lined
Wastewater Pond
Septic Tank,
Higher Level
Treatment Unit,
Dosing Tank,
Vault or Vault
Privy
43
FIG. C.1
Septic
Tank,
Higher level
treatment
Unit,
Dosing
Tank, Vault
or Privy
10
N/A
10
Dry
Gulch,
Cut
Bank,
Fiil
Area
(from
Crest)
15
25
10
Lake,
Water
Course,
lrrigation
Ditch,
Stream,
Wetland
25
100
253
Subsurface
Drain,
lntermittent
lrrigation
Lateral,
Drywell,
Stormwater
Structure
25
25
0
Property
Lines,
Piped or
Lined
lrrigation
Ditch,
upslope
curtain
drain
10
25
10
Structure
without
basement,
crawl
space^or
footing
drains
15
25
1255
Structure
Wbasement,
crawl space
or footing
drains
15
25
125
Potable
Water
Supply
Line 2
252
502
102
Spring,
Well,1
Suction
Line,
Potable
Water
Supply
Cistern4
100
100
100 3
Unlined Sand
Filter in SoilWith
a Percolation Rate
Slower than 60
Minutes per lnch,
Unlined or
Partially Lined
Evapotrans-
piration System,
Outside of Berm
of Unlined 1
Wastewater Pond,
or System Not
Relying on STA
for Treatment
Other than
Aerosol
Slit Trench
Latrine, Pit Priw
System Not
Relying on STA
for Dispersal
CODE OF COLORADO REGULATION
Water Qualitv Control Commission
5 CCR 1002-43
NOTE: The minimum distances shown above must be maintained between the OWTS components and the features described. Where soil, geological or other conditions warrant,
or upgrading of existing OWTS where the size of lot precludes adherence to these distances, a repaired OWTS must not be closer to setback features than the existing OWTS, as
reviewed and approved by the local public health agency. Components that are not \^,atertight should not extend into areas of the root system of nearby trees.
1 lncludes potable wells, irrigation wells and monitoring wells set within a potable aquifer and inflhation galleries permitted as wells by the Division of Water Resources.
4
FtG. C-2
CODE OF COLORADO REGULATION
Water Qualitv Control Commission
5 CCR 100243
2 Crossings or encroachments may be permitted at the points as noted above provided that the water or wastewater conveyance pipe is encased for the minimum setback
distance on each side of the crossing. A length of pipe with a minimum Schedule 40 rating [ASTM Standard D 3034-16 (2016 version)] of sufficient diameter to easily slide over and
completely encase the conveyance must be used. Rigid end caps of at least Schedule 40 rating [ASTM Standard D 3034-16 (2016 version)] must be glued or secured in a watertight
the bottom of the encasement pipe. The area in which the pipe passes through the end caps must be sealed with an approved underground sealant compatible with the piping used.
Other methods of encasement that provide equal protection are allowed. These methods must be reviewed and approved by the local public health agency'
3 Add eight feet additional distance for each 100 gallons per day of design flows between 1,000 and 2,000 gallons per day, unless it can be demonstrated by a,professional
required to minimize contamination as part of the Division site application and permitting process.
4 All horizontal setbacks to a potable water supply cistern must be met unless a variance by the Board of Examiners of Water Well Construction and Pump lnstallation
1 1 .4 of the Waier Well Construction Rules, as applicable. The minimum horizontal setback that may be granted through a variance is to 25 feet.
5 lf the structure is not used as a habitable unit, the isolation may be reduced by the local board of health to no less than 50 feet.
6. Building sewer installations shall meet the design requirements of the Colorado Plumbing Code.
45
FtG. C-3