HomeMy WebLinkAboutObservation of Excavation 10.24.2023
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
October 24, 2023
SCIB, LLC
Attn: Luke Gosda
0115 Boomerang Road
Suite 5201B
Aspen, Colorado 81611
luke.gosda@sunriseco.com
Project No. 21-7-437.A
Subject: Observation of Excavation, Proposed Residence, Lot 54, Ironbridge Phase 3,
Blue Heron Drive, Garfield County, Colorado
Dear Luke:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on September 29, 2023 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations for the foundation support are presented in this report. The
services were performed in accordance with our previous agreement for professional engineering
services to you dated May 10, 2021.
At the time of our visit to the site, the foundation excavation had been cut in three levels from
5 to 6½ feet below the adjacent ground surface. The soils exposed in the bottom of the
excavation consisted of the natural silty clay soils. The results of a gradation, Atterberg Limits
and proctor compaction analysis performed on a sample of Class 6 road base used for under
footing structural fill are presented on Figures 1 and 1A. No free water was encountered in
the excavation and the soils were moist. Density testing was performed on the structural fill as
it was placed and the test results are attached and indicated that satisfactory compaction was
achieved.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the structural fill should be adequate for support of the
proposed residence. Footings should be a minimum width of 16 inches for continuous walls
and 2 feet for columns. Exterior footings should be provided with adequate soil cover above
their bearing elevations for frost protection. Continuous foundation walls should be reinforced
top and bottom to span local anomalies such as by assuming an unsupported length of at least
10 feet. Backfill placed around the structure should be compacted and the surface graded to
prevent ponding within at least 10 feet of the building.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
subsurface conditions within the loaded depth of foundation influence. This study is based on
the assumption that soils beneath the footings have equal or better support than those exposed.
Tested By: KO Checked By: SLP
Laboratory Proctor Compaction Test Report
Dr
y
d
e
n
s
i
t
y
,
p
c
f
132
133
134
135
136
137
Water content, %
6 6.5 7 7.5 8 8.5 9
7.5%, 135.1 pcf
Test specification:ASTM D 698-12 Method C Standard
GP-GM A-1-a NV NP 0.0 11.0
Class 6 Aggregate Base Course
21-7-437.A SCIB, LLC
See Figure 1A for classification results.
1
Elev/Classification Nat.Sp.G.LL PI % >% <
Depth USCS AASHTO Moist.3/4 in.No.200
TEST RESULTS MATERIAL DESCRIPTION
Project No.Client:Remarks:
Project:
Location: WSM Sample Number: 291-23
Kumar & Associates, Inc.
Glenwood Springs, Colorado Figure
Maximum dry density = 135.1 pcf
Optimum moisture = 7.5 %
Blue Heron Drive, Lot 54, Ironbridge Phase 3, Garfield County, Colorado
Tested By: KO Checked By: SLP
Kumar & Associates, Inc.
Glenwood Springs, Colorado
9/29/2023
1A
CDOT Class 6 Aggregate Base Course
PL=LL=PI=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
USCS=AASHTO=
*
Class 6 Aggregate Base Course
1
.75
.375
#4
#8
#16
#30
#50
#100
#200
100.0
100.0
77.0
55.0
43.0
35.0
27.0
19.0
15.0
11.0
100.0
95.0 - 100.0
30.0 - 65.0
25.0 - 55.0
3.0 - 12.0
NP NV NP
14.0933 12.1219 5.5638
3.5491 0.7732 0.1500
GP-GM A-1-a
See Figure 1 for standard Proctor compaction results.
SCIB, LLC
Blue Heron Drive, Lot 54, Ironbridge Phase 3, Garfield County, Colorado
21-7-437.A
Soil Description
Atterberg Limits
Coefficients
Classification
Remarks
Location: WSM
Sample Number: 291-23 Date:
Client:
Project:
Project No:Figure
SIEVE PERCENT SPEC.*PASS?
SIZE FINER PERCENT (X=NO)
PE
R
C
E
N
T
F
I
N
E
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0010.010.1110100
CDOT Class 6 Aggregate Base Course
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 45.0 13.9 18.1 12.0 11.0
6
i
n
.
3
i
n
.
2
i
n
.
1½ i
n
.
1
i
n
.
¾ i
n
.
½ i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Particle Size Distribution Report