HomeMy WebLinkAboutAs-BuiltsEXISTING DRIVEWAY
INSTALLED CHAMBER END CAP
ON ALL END CHAMBERS
TOP PERIMETER OF FIELD SURFACE IS
MOUNDED 6" ABOVE SURFACE GRADES
EX 4" SCHD-40 PVC EFFLUENT
PIPE @ MIN. 2%, INSTALLED 2019
6.0'
40.0'
EXCAVATION DEPTH APPROX,
3' BELOW EXISTING GRADE
BALLARD BARRIERS IN PLACE TO PROTECT
AREA FROM VEHICULAR TRAFFIC
EXISTING BUILDING
98' X 50'
EXISTING OIL/SAND
TANK IRON R&C LIDS
49.94'
EX 4" PVC SEWER PIPE @ 2%,
INSTALLED 4" 2-WAY CLEANOUT
INV. 2.0' BELOW EX GRADE± 2019
EX-4" SEWER PIPE TO BE RECOVERED, SEVERED AND INSTALLED INTO
INLET OF NEW PLASTIC OR CONC. DISTRIBUTION BOX WITH RISERS
AND LID SET TO SURFACE GRADE. INSTALL LEVEL ON COMPACTED ABC
AS-CONSTRUCTED SOIL TREATMENT AREA
INSTALLED 16 ARC-36 CHAMBERS IN SINGLE BED WITH 2 ROWS OF 8 CHAMBERS PER
ROW FOR A TOTAL ABSORPTION AREA OF 240 S.F. THE BOTTOM OF EACH TRENCH
WAS EXCAVATED TO AN AVERAGE DEPTH OF 30 INCHES BELOW THE EXISTING
SURFACE GRADES. SURFACE BACKFILLED 6" ABOVE EXISTING PERIMETER GRADES,
FINISHED WITH XERISCAPE GROUND COVERS AND MULCH
INSTALLED 4" INSPECTION PORT EXTEND PIPE RISER FROM END
CHAMBER IP FLANGE TO FINISH GRADE W/ PUSH ON CAP & COVERED
WITH 8" DIA. VALVE BOX SET WITH LID 4" ABOVE FINSH GRADE
(TYP. EACH PROXIMAL & DISTAL END CHAMBER EACH ROW )
2 RESTROOMS
1WC W/LAV EA.
96"X8" FLOOR TRENCH
DRAINS W/ IRON GRATE
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EX POTABLE WATER SERVICE PIPE
INSTALLED INSPECTION PORT
(TYP. BOTH ENDS EACH CHAMBER ROW)
4" FLOOR DRAIN PIPE TO
OIL /SAND BMP TANK
NO FLOORS DRAINS CONNECTED
TO OWTS SEWER SERVICE
4" DISTRIBUTION
GRAVITY LINE
FROM SEPTIC TANK
INVERT IN
N.T.S.
4" SOLID PVC GRAVITY
DISTRIBUTION PIPES (TYP.)
TO ABSORPTION FEILD
BAFFLE
COMPACTED SUBGRADE
8" AGREGATE BASE COURSE
RISER SECTION
DISTRIBUTION BOX LID
AT GROUND SURFACE
1 inch = ft.
( IN FEET )
GRAPHIC SCALE
0
MACKEY OWTS Upgrade Design Calculations
The proposed upgraded onsite wastewater treatment system (OWTS) design flow is calculated as
follows for low usage commercial shop facility that serves two mechanical repair shops each with
a single restroom (toilet and lavatory) & 1 small washer/dryer in 1 shop.
From the Regulation 43 usage Table 6-2 :
Max. Design flow (Qd) = # of people x (avg.per capita flow)
Qd=daily worker office: 8 persons @ 15 gpd = 10 x 15 = 120 gpd
Qd=transient Vistor: 4 persons @ 5 gpd = 4 x 5 = 20 gpd
Qd=single small washing machine: 1 @ 20 gpd
Total Design flow Qd = 120+20+20 =160 gpd
Septic Tank Design:
Continue use of the existing 1000 gallon, two compartment concrete septic tank with a new
effluent filter to be installed on the existing 4" outlet pipe end that extends into the tank and
accessible below the riser lid in in the second chamber. Extend new filter handle to within 6" of lid.
Tank was installed with sealed PVC risers and plastic lids set at the finish grade surface to be
maintained.
Sub Surface Conditions and Testing:
Subsurface soil investigations and USDA soil texture method tests were performed by Sopris
Engineering on October 25, 2018. The soils in the area of the proposed absorption field were
sampled and characterized by application of the USDA soil texture method analysis. The soils were
tested to determine the hydraulic loading rate and to confirm the appropriate absorptive surface
suitable for conventional absorption systems in native soils. Two excavated profile pits 1 & 2 were
observed in the East central portion of the site adjacent to the proposed field location. The soils
below 4 to 9 inches of mixed surface fill & topsoil consist of medium dense sandy silt loam with
moderate granular to slightly blocky structure with some cobbles and gravels. The percentage of
cobbles and gravels below 24 inches was less than 20% in the sandy silt loam to the 7 foot depth
explored in both pits. The soil appears to be consistent across the site.
The native soils sampled from 2-3 feet below the surface are characterized as a soil type 2
consisting of silt loam texture with moderate granular structure. This soil has an effective loading
rate for conventional soil treatment of 0.60 gal/S.F./day for a level 1 conventional treatment
system. The equivalent percolation rate is assumed to be approximately 16-25 minutes per inch.
Sandy silt loam with cobbles and gravels < 30% are encountered at shallow depths within 2-feet of
the existing surface grade. No free water was encountered in the excavations on site.
Groundwater levels are expected to be well below 10 feet from the existing surface grades. The
soils ares suitable for a conventional shallow absorption field consisting of gravelless infiltration
chamber units.
An additional shallow excavation was observed during a recent evaluation of the existing OWTS
conditions performed by Voskuil Operations in coordination with Sopris Engineering on October 8,
2025. Voskuil performed an initial OWTS inspection on 08-06-25 observing a full tank with inflow
from a leaking toilet and saturated conditions in the existing STA. The tank and chamber were
pumped out the following evening on 08-07-25 and the leaking toilet was repaired. The follow up
inspection the next day indicated that the wetted soils in the existing chamber trench were
allowing infiltration as no standing water was observed.
Observation of the shallow excavation at the proximal end of the trench indicated that previously
saturated water was infiltrating into the native sandy silt loam soils. The area was excavated to a
depth of approximately 3.25' below the surface grade, exposing the 4" effluent pipe, first
chamber, inspection port and part of the second chamber. No ponding water was observed in the
shallow excavation or the STA at the time of observation. The existing absorptive surface is 2 to
2.5 feet below the existing grades along the existing trench. The proposed expanded STA
replacement will be excavated with the absorptive surface established 3 to 3.5 feet below the
finish surface grade.
Additional soil evaluations will be performed by the engineer during construction to verify the
soils in the entire replacement STA field excavation prior to installation of the OWTS components.
All observations and installation conditions will be reported in the As-Constructed documentation
with appropriate photo documentation.
Treatment-Soil Treatment Unit/ Absorption System Design:
The upgrade treatment/absorption field is designed based on utilizing the effective Long Term
Acceptance Rate (LTAR) for the native soils and the application of appropriate loading factors for a
soil treatment unit system utilizing gravity distribution to a gravelless chamber bed. The new
treatment system and absorption field will consist of gravity distribution of septic tank effluent via
a distribution box to individual chamber rows with treatment across the scarified native soil
absorptive surface.
Long Term Acceptance Rate (LTAR)
Wastewater Treatment Level 1; loading rate for silt loam is (0.60 gal./S.F./day) for soil type 2.;
Loading factors; (Table 10-2, Gravity application bed = 1.2 ) and
(Table 10-3, gravelless chambers = 0.7)
A(sf) = QdxLF1x LF2 .: A = Area;
LTAR LTAR = 0.60 Gal/S.F./day for silt loam
Qd = flow (gal/day) = 160 gpd
L.F.1=1.2 Gravity Distribution Bed
L.F.2=0.7 Chambers
A(sf) = 160 gpd x 1.2 x 0.7 = 224 S.F.
0.60 Gal/S.F./day
Number of Arc-36 (5' long ) chambers:
224 S.F = 14.9 chambers, Install 16 ADS Arc-36 Biodiffuser chambers
15 S.F./Chamber Total Absorption area provided is 240 S.F.
Install 20 Biodiffuser chambers in two rows 50' long by 3' wide plus two end caps as delineated on
the plan or equivalent Quick 4 chambers. The septic tank effluent will be gravity distributed to the
head of each chamber row via a 4" distribution pipe from the concrete distribution box.
NATIVE, YARD OR LANDSCAPED SURFACE
N.T.S.
TO 90% STANDARD PROCTOR
EXCAVATED MATERIAL COMPACTED
COMPACTED SUBGRADE
SUITABLE BACKFILL OR
CLASS 6 ROAD BASE
GENERAL NOTES:
1.THE OWTS AS SHOWN ON THE PLAN AND THE DETAILS WERE DESIGNED BY SOPRIS ENGINEERING.
2.THE EXISTING/ PROPOSED LOT CONDITIONS AND SURVEY/PLAT INFORMATION SHOWN IS BASED ON
THE SITE PLAN SHEET 1 OF 1, BY SEXTON SURVEY COMPANY, DATED 10/31/18
3.PRIMARY OWNER NAME AND ADDRESS: MACKEY, GREGG, PO BOX 398, BASALT, CO, 81621
4.SITE ADDRESS: 50 110 COUNTY RD, GLENWOOD SPRINGS
5.Legal Summary: SECTION: 7 TOWNSHIP: 7 RANGE: 88 TR IN LOTS 5 & 1
6.Parcel Number: 2393-074-00-012
7.PREVIOUS GARFIELD COUNTY SEPTIC PERMIT #: permit # SEPT-11-18-5581 ISSUED: 11-29-18, New
County OWTS Permit SEPT-9487.
8.CONTRACTOR: Voskuil Operations
DATE REVISION
C-1.0
DRAWING NO.
TITLE
OWTS RECORD
DRAWING
AS-CONSTRUCTED
CONDITIONS
18197.02JOB NO.
DATE:03-18-26
DESIGNED BY
DRAWN BY
CHECKED BY
PER
WJB 08/19/25
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NOTE: ALL CHAMBERS IN THE BED MUST BE INSTALLED ON LEVEL GRADE
MAXIMUM DEPTH OF TRENCHES NOT TO EXCEED 36" BELOW PROPOSED SURFACE
GRADES. INLET AND END CAPS ARE TO BE INSTALLED ON EACH END CHAMBER
ROW. IF EXCESSIVE LARGE COBBLES OR BOULDERS ARE ENCOUNTERED IN ANY
PART OF THE EXCAVATION, OVER EXCVATE AND BACKFILL WITH SAND OR
SUITABLE SCREENED NATIVE SOILS.
CROWN FIELD TRENCH TO
DIVERT SURFACE WATER
FILTER FABRIC
6'
LEACHING
CHAMBER
12"
6"
N.T.S.
4" PVC INLET PORT
IN END CAP
UNDISTURBED EARTH
SILTY LOAM SOIL.
XEROCPAPE GROUND COVER
AND MULCH
SCARIFY/TILL BOTTOM
SURFACE TO A DEPTH OF 3
BACKFILL WITH SCREENED
ONSITE SOILS FREE OF ROCKS IN
EXCESS OF 3" DIAMETER
BACKFILL LAYER NATURAL ONSITE
SOILS FREE OF ROCKS
MIN 12"
SCARIFY/TILL BOTTOM
SURFACE TO A DEPTH OF 3"
YTN
03-18-26
03-18-26
3/18/2026