HomeMy WebLinkAboutSite and Soil Evaluation 10.13.2022CTLITHOMPSON
October 13, 2022
Green Line Architects
65 N. 4th Street, Suite 5
Carbondale, CO 81623
Attention: Steve A. Novy, AIA
Principal
Subject: Site and Soil Evaluation
High Aspen Ranch, Phase 2
491 High Aspen Drive
(a.k.a. Lot 31, High Aspen Ranch)
Assessor's Parcel Number: 218736104031
Garfield County, Colorado
Project No. GS06546.001-132
CTLIThompson, Inc. (CTLIT) was retained to perform a site and soil evalu-
ation, as well as the design of an on -site wastewater treatment system (OWTS)
for the residence and garage/office building proposed at 491 High Aspen Drive in
Garfield County, Colorado. This letter provide results from our site and soil evalu-
ation. Our OWTS design will be provided in a subsequent letter.
The subject site is an approximately 36.02-acre parcel accessed by High
Aspen Drive to the north. A vicinity map with the location of the site is included as
Figure 1. An aerial photograph of the site is shown on Figure 2. An existing resi-
dence and shop building on the property have been deconstructed. The Soil
Treatment Area (STA) that serviced the previous buildings will be removed and
replaced with a new system.
A representative of CTLIT visited the property on October 4, 2022 to per-
form the site and soil evaluation. Ground surface in the proposed Soil Treatment
Area (STA) slopes down to the southeast at grades of 8 to 12 percent. The "land-
scape position" variable for the STA classifies as "LL", pursuant to the EPA's On -
site Wastewater Treatment Systems Manual.
CTLIT investigated subsurface conditions below the proposed STA by ob-
serving a trackhoe excavate two profile pits (TP-1 and TP-2) at the approximate
locations shown on Figure 2. Subsoils exposed in our profile pits consisted of ap-
proximately 6 to 8-inches of topsoil over natural, sandy clay to the total exca-
vated depth of 8 feet.
Graphic logs of subsurface conditions found in our profile pits are shown
on Figure 3. We did not find limiting layers in the subsoils. Groundwater was not
encountered in our profile pits at the time of excavation. No redoximorphic fea-
tures were observed in the pits.
CTLIThompson, Inc.
Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County — Colorado
Cheyenne, Wyoming and Bozeman, Montana
We performed grain -size analysis on two samples of soil obtained from
our profile pits. Gradation test results are included as Figure 4. Based on Table
10-1 in the Garfield County OWTS regulations, the sandy clay soil classifies as
Soil Type 4A (Clay) with a corresponding Long -Term Acceptance Rate (LTAR) of
0.15 gal/day/ft2 for typical residential strength effluent (Treatment Level 1). De-
scriptions of this soil type is summarized on Table 10-1 of the OWTS design reg-
ulations published by Garfield County Environmental Health Department.
Our OWTS design report is forthcoming. Please contact us if you have
questions or need additional information.
CTLITHOMPSON, INC.
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Ryan R. Barbone, E.I.T.
Division Manager
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GREEN LINE ARCHITECTS 2
HIGH ASPEN RANCH, PHASE 2
CTLIT PROJECT NO. GS06546.001-132
0 500 1000
SCALE: 1 " = 1000'
NOTE: SATELLITE IMAGE FROM MAXAR
(COPYRIGHT 2021)
GREEN LINE ARCHITECTS Vicinity
491 HIGH ASPEN DRIVE, PHASE 2
PROJECT NO. GS06546.001-132 Map
u
Fig. 1
0 50 100
SCALE: 1" = 100'
LEGEND:
TP-1 APPROXIMATE LOCATION OF
0 PROFILE PIT
NOTE: SATELLITE IMAGE FROM MAXAR
(COPYRIGHT 2022)
491High Aspen Drive, Phase 1
V2
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41
Al
GREEN LINE ARCHITECTS Aerial
491 HIGH ASPEN DRIVE, PHASE 2 Photograph
PROJECT NO. GS06546.001-132 FIA. 2
TP-1 TP-2
0 0 LEGEND:
TOPSOIL, CLAY, SANDY, ORGANICS, MOIST, DARK
BROWN, BLACK.
5 5 F1CLAY, MASSIVE SHAPE, LOOSE (SINGLE GRAIN)
GRADE, LOOSE CONSISTENCY, DARK BROWN, GRAY.
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w
LL
2
F-
a
w
BULK SAMPLE FROM SIDEWALL OF EXCAVATION.
10 10
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NOTES:
1.
PROFILE PITS WERE EXCAVATED WITH A TRACKHOE
ON OCTOBER 4, 2022. PITS WERE BACKFILLED
IMMEDIATELY AFTER EXCAVATION OPERATIONS
WERE COMPLETED.
2.
SOIL EVALUATION CONDUCTED BY RYAN BARBONE,
E.I.T. (CPOW SOILS CLASS CERTIFIED)
3.
GROUNDWATER WAS NOT ENCOUNTERED AT THE
TIME OF EXCAVATION. REDOXIMORPHIC FEATURES
WERE NOT OBSERVED IN OUR PITS.
4.
THESE LOGS ARE SUBJECT TO THE EXPLANATIONS,
LIMITATIONS, AND CONCLUSIONS CONTAINED IN THIS
LETTER.
Summary Logs of
Profile
GREEN LINE ARCHITECTS
Pits
491 HIGH ASPEN DRIVE, PHASE 2
CTLIT PROJECT NO. GS06546.001-132
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LASTIC) TO SILT (NON -PLASTIC)
Sample of SOIL TYPE 4A (CLAY)
From TIP - 1 AT 3-4 FEET
GRAVEL 1 % SAND 10 %
SILT & CLAY 89 % LIQUID LIMIT %
PLASTICITY INDEX %
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CLAY (PLASTIC) TO SILT (NON -PLASTIC)
Sample of SOIL TYPE 4A (CLAY)
From TIP - 2 AT 3-4 FEET
GREEN LINE ARCHITECTS
HIGH ASPEN RANCH, PHASE 2
CTLIT PROJECT NO. GS06546.001-132
GRAVEL 1 % SAND 6 %
SILT & CLAY 93 % LIQUID LIMIT %
PLASTICITY INDEX %
Gradation
Test Results
FIG. 4