HomeMy WebLinkAboutObservation of Pit for OWTS DesignKilffilfiffiffimi'{s;i*.'-
rtn Srployoc O*rtccl Compcay
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
ww'w.kumarusa.gom
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
November 15,2022
Wes Gardner
P.O. Box 1628
Carbondale, Colorado 81 623
wes. gradner@thebridgenetworkcolorado.com
Project No.22-7-l 15.A
Subject: Observation of Pit for Septic Design, Proposed Residence, 9lT4Highway 82,
Garfield County, Colorado
Dear Wes:
As requested, Kumar & Associates, Inc. observed a pit, previously excavated in the proposed
septic area for evaluation of the exposed soils for septic disposal feasibility at the subject site.
The septic disposal system is proposed to be located northwest of the residence and well back
from the steep slope down to the river.
The area of the proposed septic system is relatively flat with a slight slope down to the west. The
subsurface conditions at the septic area were evaluated by observing a profile pit previously dug
in the middle of the proposed septic disposal area. The soils encountered in the pit consisted of
about 1 foot of topsoil overlying relatively dense, slightly silty sandy gravel down to the bottom
of the pit at about 6 feet. Results of a gradation analysis performed on a sample of the slightly
silty sandy gravel (minus 3-inch fraction) obtained from the site are presented on Figure 1. No
free water was observed in the pits at the time of observation and the soils were slightly moist.
Based on the subsurface conditions encountered and the gradation test results, the tested area
should be suitable for a conventional infiltration septic disposal system. Our experience in this
area is that the gravels soils are typically deep and groundwater is close to the nearby river level
which is well below the site. The soils classify as R-O. We recommend the infiltration area
have a sand filter installed below the system due to the relatively low fines content of the gravel
soils. A civil engineer should design the infiltration septic disposal system.
Limitations: This study has been conducted in accordance with generally accepted geotechnical
engineering principles and practices in this area atthis time. We make no warranty either
express or implied. The conclusions and recommendations submiued in this report are based
upon the data obtained from the exploratory pit excavated at the septic area. Our findings
include extrapolation of the subsurface conditions identified at the exploratory pit and variations
in the subsurface conditions may not become evident until excavation is performed. If
conditions encountered during construction appear different from those described in this report,
we should be notified at once so re-evaluation of the recommendations may be made.
This report has been prepared for the exclusive use by our client for design purposes. We are not
responsible for technical interpretations by others of our information. As the project evolves, we
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should provide continued cnnsultation and field services during construction to review and
monitor the implsmentation of our recommendations, and to veriry that the recommendations
have been appropriately inlerpreted. Significant design changes may require additional analysis
or modifications to the recommendations presented herein.
If you have any questions or if we may be of further assistance, please let us know.
Respectfully Submitted,
Kxrwnv & Ass**i*tesu
Daniel E. Hardin,
DEHlkac
attachments Figure I Results
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ETER SIEVE ANALYSIS
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READINGS U.S. STANDARD SERIES
#140 #60 #35 #1A
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24 HF, 7 HR 1 MIN.
4MIN,#4 3/8', 314', 1 112' 3'6" 8"
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10 90
20 80
30 70
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100 .001 .002 ,005 .009 .019 .045 106 .025 ,500 1.00 2.00 4.75 9.5 19.0 37.5 76.2 152 203
DIAMETER OF PARTICLES IN MILLIMETERS
CLAY COBBLES
GRAVEL 76 lO SAND 21 o/o SILT 3 o/"
USDA SOIL TYPE: Extremely Gravelly Sand FROM: Profile Pit @ 2'-3'
V. FINE FINE MEDIUM COARSE SMALL MEDIUM I ARGFSILT
22-7 -1 15A Kumar & Associates USDA GRADATION TEST RESULTS 1Fig