HomeMy WebLinkAboutFIRST CHRISTIAN CHURCH PUD PHASE IV PRELIMINARY AND FINAL - 51 93 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTMOI STU R E -DENS ITY DETERM I NATION
Samples of representative fill materials to be placed shall be fur-
nished by the contractor to the soils engineer for determination of
maximum density and optimum moisture or percent of Relative Density
for these materials. Tests for this determination will be made using
methods conforming to requirements of ASTM D 698, ASTM D 1557, or
ASTM D 2049. Copies of the results of these tests will be furnished
to the contractor. These test results shall be the basis of control
for all compaction effort.
DENSITY TESTS
The density and moisture content of each layer of compacted fill will
be determined by the soils engineer in accordance with ASTM D 1556,
ASTM'D 2167, or ASTM D 2922. Any material found not to comply with
the minimum specified density shall be recompacted until the required
density is obtained. The results of all density tests will be furnished
to both the owner and the contractor by the soils engineer.
C-4
P L A C I N G F I L L
No sod, brush, frozen material, or other unsuitable material shall be
placed in the fill. Distribution of material in,the fill shall be such
as to preclude the formation of lenses of material differina from the
surrounding material. The materials shall be delivered to and spread
on the fill surface in a manner which will result in a uniformly com-
pacted fill. Prior to compacting, each layer shall have a maximum
thickness of eiaht inches, and its upper surface shall be approximately
horizontal.
MOISTURE CONTROL
While being compacted, the fill material in each layer shall as nearly
as practical contain the amount of moisture required for optimum com-
paction or as specified, and the moisture shall be uniform throughout
the fill. The contractor max/ be required to add necessary moisture to
the fill material and to uniformly mix the water with the fill material
if, in the opinion of the soils engineer, it is not possible to obtain
uniform moisture content by adding water on the fill surface. If, in
the opinion of the soils engineer, the material proposed for use in
the compacted fill is too wet to permit adequate compaction, it shall
be dried in an acceptable manner prior to placement and compaction.
COMPACTION
When an acceptable, uniform moisture content is obtained, each layer
shall be compacted by a method acceptable to the soils engineer and
as specified in the foregoing report as determined by applicable
standards. Compaction shall be performed by rolling with approved
tamping rollers, pneumatic -tired rollers, three -wheel power rollers,
vibratory compactors or other approved equipment well -suited to the
soil beino compacted. If a sheepfoot roller is used, it shall be
provided with cleaner bars attached in a manner which will prevent
the accumulation of material between the tamper feet. The rollers
should be designed so that the effective weight can be increased.
r �
APPENDIX C
Suggested Specifications for Placement of Compacted Earth Fill
and/or Backfills.
GENERAL
A soils engineer shall be the owner's representative to inspect and
control all compacted fill and/or compacted backfill placed on the
project. The soils engineer shall approve all earth materials prior
to their use, the methods of placing, and the degree of compaction
obtained. A verification of approval from the soils enaineer will be
required prior to the owner's final acceptance of the filling opera-
tions.
MATERIALS
Soils used for all compacted fill beneath interior floor slabs shall
be a granular, nonexpansive type. The upper 12" to 18" of compacted
earth backfill placed adjacent to exterior foundation walls.shall be
an impervious, nonexpansive material. No material having a maximum
dimension greater than six inches shall be placed in any fill. All
materials proposed for use in compacted fill and/or compacted back -
fill shall be approved prior to their use by the soils engineer.
PREPARATION OF S U B G R A D E
All topsoil, vegetation, debris, and other unsuitable material shall
be removed to a depth satisfactory to the soils engineer before begin-
nino preparation of the subgrade. The subgrade surface of the area
to be filled shall be scarified a minimum depth of six inches, mois-
tened as necessary, and compacted in a manner specified below for the
subsequent layers of fill. Fill shall not be placed on frozen or
muddy ground.
C-2
APPENDIX C.
Atterberg Summary
Boring Number
1
3
10
20
23
25
27.
Depth (Ft.)
7.0-8.0
13.0-14.0
3.0-4.0
2.0-3.0
2.0-3.0
2.0-3.0
2.0-3.
Liquid Limit
28.5
29.5
30.9
35.9
39.9
48.2
39.3
Plastic Limit
16.0•
13.2
14.3
18.8
19.9
19.3
17.1
Plasticity Index
12.5
16.3
16.6
17.1
20.0
28.9
22.2
% Passing #200 Sieve
54.1
44.2
72.9
86.6
92.0
84.7
77.9
Group Index
4.8
4.3
10.0
10.8
12.0
16.7
12.9
Classification
Unified
CL
Sc.
CL
CL
CL
CL
CL
AASHTO
A-6(5)
A4(4)
A-6(10)
A-6(11)
A-6(12)
A-7-6(17)
A-6(13)
SUMMARY OF TEST RESULTS
Swelling Pressures
Boring Depth % Moisture Dry Density Swelling
No. (Ft.) Before Test P.C.F. Pressure PSF
4
3.0-4.0
15.7
96.3
325
5
3.0-4.0
17.5
92.8
455
17
3.0-4.0
16.3
109.6
640
19
3.0-4.0
19.9
108.7
280
R-14
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
26
2.0-3.0
11.8
97.5
5240Q
3.0-4.0
11.5
5/12
8.0-9.0
13.7
5/12
27'
2.0-3.0
17.4
105.7
39530
3.0-4.0
16.2
6/12
8.0-9.0
12.5
7/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
21
2.0-3.0
17.4
105.7
5,400
3.0-4.0
12.4
8/12
8.0-9.0
19.5
5/12
22
2.0-3.0
21.6
97.1
2,720
3.0=4.0
23.6
4/1.2
8.0-9.0
13.0
5/12
23
2.073.0
22.0
97.8
3,540
3.0-4.0
24.0.
5/12
8.0-9.0
17.0
4/12
24
2.0-3.0
22.8
94.9
2,370
3.Q-4.0
26.0
3/12
8.0-9.Q
1915
4/12
25
2.0-3.0
21.2
1Q2,2
5,25Q .
3.0-4.Q
21.6
10/12
8.0-9..0
15.2
8/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
17 (cont.)
34.0-35.0
19.6
14/12
39:0-40.0
26.1
34/12
44.0-44.8
17.5
50/10
H2O
2.258
18
3.0-4.0
16.4
100.7
4,530
4.0-5.0
19.4
5/12
7.0-8.0
26.0
92.1
8.0-9.0
19.2
4/12
13.5-14.5
19.8
4/12
18.5-19.5
15.6
5/12
19
.3.0-4.0
19.9
1Q2.7
3,410
4.0-5.0
21.9
6/12
7.0-8.Q
8.0-9.0
19.1
5/12
13.5-14.5
21.9
5/12
20
2.0-3.0
16.8
101.1
7,320
3.0-4.0
17.7
3/12
8.0-9.0
19.7
4/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING DEPTH % DRY DENSITY UNCONFINED COMPRESSIVE WATER SOLUBLE PENETRATION
NO. FT. MOISTURE P.C.F. STRENGTH-P.S.F. SULFATES-% BLOWS/INCHES
15 3.0-4.0 16.3 97.8 2410
4.0-5.0 16.7 6/12
7.0-8.0 27.2 93.4 1530
8.0-9.0 24.2 4/12
13.5-14.5 19.3 9/12
16 2.0-3.0 10.5 98.0 1810
3.0-4.0 7/12
6.0-7.0 24.3 92.0
7.0-8.0 26.5 4/12
12.0=13.0 18.0 115.0
13.0-14.0 14.4 11/12
17 3.0-4.0 16.3 113.3 8240
4.0-5.0 19.1 9/12
7.0-8.0 22.6 98.6 1540
8.0-9.0 17.5 6/12
13.0-13.5
.13.5-14.5 15.9 14/12
19.0-20.0 19.0 6/12
24.0-25.0 19.0 14/12
29.0-30.0 21.5 8/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
12
3.0-4.0
12.8
104.8
3890
.018
4.0-5.0
15.5
8/12
7.0-8.0
21A
98.5
1480
8.0-9.0
27.1
4/12
13.5-14.5
16.4
7/12
13
1.0-2.0
11.8
100.8
7930
2.0-3.0
11.4
10/12
5.0-6.0
24.3
94.8
1750
6.04*0
18.9
4/12
10.5711.5.
17.5
11.2.5
810
11.5-12.5
13.1
12/12 .
13.5-14.5
4/12
14
3.0-4.0
17.7
102.2
4130
4.075.0
22.0
4/12
7.0-8.0
25.1
97.0
1210
8.0-9.0
22.2
3/12
13.5-14.5
21.2
4/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
8
3.0-4.0
22.0
92.3
3260
4.0-5.0
15.6
5/12
7.0-8.0
15.0
107.5
1280
.058
8.0-9.0
26.2
2/12
13.5-14.5
14.6
5/12
9
3.04.0
16.6
103.1
2090
4.0-5..0
14.1
5/12
7.0-8.0
30.3
88.6
1160
8.0-9.0
33.9
3/12
13.5=14.5
13.0
36/12
10
3.0-4.0
13.7
108.9
3820
4.0-5.0
13.4
4/12
7.0-8.0
16.0
102.5
8.0-9.0
22.0
3/12
13.5-14.5
15.7
10/12
11
3.0-4.0
15.8
101.5
4020
4.0-5.0
18.5
5/12
7.0-8.0
25.5
98.4
8.0-9.0
24.9
3/12
13.5-14.5
6/12
18.5-19.5
17.5
7/12
EMPIRE LABORATORIES, INC
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
5 (cont.)
44.0-45.0
14.9
19/12
49.0-50.0
21.1
9/12
54.0-55.0
23.0
31/12
59.0-60.0
21.3
.0500
46/12
64.0-64.7
19.1
50/8
6
3.0-4.0
18.4
102.1
2070
4.0-5.0
24.1
3/12
7.0-8.0
19.2
101.0
8.0-9.0
24.1
3/12
13.5=14.5
13.7
14/12
7
3.0-4.0
20.9
101.4
2470
4.0-5.0
25.4
4/12
7.0-8.0
25.4
95.9
8.0-9.0
22.6
4/12
13.5-14.5
13.4
16/12
I
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
3 (cont.)
44.0-45.0
11.4
40/12
48.0-49.0
22.0
13/12
54.0-54.8
24.8 .
50/9
59.0-59.2
17.5
50/3
4
3.0-4.0
15.7
104.5
4860
4.0-5.0
20.8
6/12
7.0-8.0
18.5
109.9.
1670
8.0-9.0
21.7
3/12
13.5=14.5
15.1
7/12
H2O `
2.310
5
3.0-4.0
17.5
92.7
5190
4.0-5:0
21.6
7/12
7.0-8.0
20:9
100.7
8.0-9.0
17.9
.4/12
13.0-14.0
14.0-15.0
26.8
4/12
18.0-19.*0
.18.1
5/12
24.0-25.0
22.6
1.2/12
28.0-29.0
14.6
9/12
34.0-35.0
17.2
7/12
39.0-40.0
23.8
I
6/12
EMPIRE LABORATORIES, INC.
SUMMARY OF TEST RESULTS
BORING
NO.
DEPTH
FT.
%
MOISTURE
DRY DENSITY
P.C.F.
UNCONFINED COMPRESSIVE
STRENGTH-P.S.F.
WATER SOLUBLE
SULFATES-%
PENETRATION
BLOWS/INCHES
1
3.0-4.0
21.9
97.7
2540
4.0-5.0
20.0
4/12
7.0-8.0
19.0
93.6
8.0-9.0
21.9
3/12
13.5-14.5
15.2
8/12
2
3.0-4.0
15.0
96.2
6090
4.0-5.0
20.3
6/12
7.0-8.0
18.0
104.3
1590
8.0�9.0
15.2
8/12
13.5-14.5
14.4
8/12
3
3.0-4.0
22.3
92.6
1810
4.0-5.0
21.8
5/12
7.0-8.0
14.0
8.0-9.0
24.1
2/12
13.0-14.0
14.0-15.0
15.8
5/12
18.0-19.0
20.4
6/12
23.0-24.0
16.0
12/12
28.0-29.0
20.6
9/12
35.0-36.0
18.8
6/12
39.0-40.0
18.6
I
13/12
EMPIRE LABORATORIES, INC.
.68
.67
.66
.65
O .64
G .63
0
62
.61
.60
.59
0
1
J
2
3
c
4
5
6
CONSOLIDATION --SWELL TEST
�■■�enh�■��mi
=MEN 1111111kammillill
mmollilliallmoollillii
mmollillimmomillN
0.1
0.1
0.5 1.0
APPLIED PRESSURE-TONS/SQ. FT.
0.5 1.0
APPLIED PRESSURE—TONS/SQ. FT.
B-9
EMPIRE LABORATORIES, INC.
-
5 10 1
5 10
.74
.73
.72
.71
o .70
a
o .69
68
67
.66
.65
0.1
5 ,I
0.1 ....
CONSOLIDATION --SWELL TEST
0.s 1.0
APPLIED PRESSURE—TONS/SQ. FT.
as 1.0
APPLIED PRESSURE—TONS/SQ. FT.
B-8
EMPIRE LABORATORIES. INC.
BORING NO. 15 DEPTH 3' 0
DRY DENSITY 94.6 4/Ft3
% MOISTURE 16.3
s to
5 10 I
56
55
o .54
a
a .53
.52
51
50
CONSOLIDATION --SWELL TEST
0.1 0.5 1.0
APPLIED PRESSURE-TONS/SO. FT.
0.1
0.5 1.0
APPLIED PRESSURE-TONS/SO. FT.
B-7
EMPIRE LABORATORIES, INC. _
BORING NO, 14 DEPTH 7.0
DRY DENSITY 105.9 #/Ft3
1 9
MOISTURE 25.
I
5 10 i
5 10
.71
.6
■ ' ..
CONSOLIDATION --SWELL TEST
�1
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BORING NO. � 1 DEPTH % . 0
DRY DENSITY 96.9 #/Ft3
% MOISTURE 25.5 %
0.1 0.5 1.0 5 10
APPLIED PRESSURE-TONS/SQ. FT.
0.3 1.0
APPLIED PRESSURE-TONS/SQ. FT.
B-6
—EMPIRE LABORATORIES, INC.
5 10
o .47
o .46
45
CONSOLIDATION --SWELL TEST
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DRY DENSITY-Ll-2*0#/Ft
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0.1 0.5 1.0 s 10
APPLIED PRESSURE—TONS/SQ. FT.
0.1 0.5 1.0
APPLIED PRESSURE—TONS/SQ. FT.
B-5
EMPIRE LABORATORIES, INC._
5 10
.49
o .48
a
o .47
46
.45
CONSOLIDATION --SWELL TEST
BORING NO. 4 DEPTH 7.0
DRY DENSITY 0' 7 #/Ft3
% MOISTURE 1 8.5
0.1 0.5 1.0 5 10
APPLIED PRESSURE-TONS/SQ. FT.
0.1 015 1.0
APPLIED PRESSURE-TONS/SQ. FT.
B-4
EMPIRE LABORATORIES, INC.
5 10
.73
.72
O .71
a
o .70
69
.68
.67
0
1
2
a
3
u 4
CONSOLIDATION --SWELL TEST
BORING NO. 3 DEPTH 3.0
DRY DENSITY 95.5 0/Ft3
% MOISTURE 22.3
3.1 0.5 1.0 5 10
APPLIED PRESSURE-TONS/SQ. FT.
0.1 0.5 1.0
APPLIED PRESSURE-TONS/SQ. FT.
B-3
EMPIRE LABORATORIES, INC._
5 10
.71
.70
o .69
a
o .68
67
.66
0.1
CONSOLIDATION --SWELL TEST
0.5 1.0
APPLIED PRESSURE-TONS/SQ. FT.
BORING NO. DEPTI
DRY DENSITY 96.6 #/Ft3
% MOISTURE 19.0
7.01
5 10
0.1 0.5 1.0 5 10
APPLIED PRESSURE-TONS/SQ. FT.
B-2
EMPIRE LABORATORIES, INC.
APPENDIX B.
LOG OF BORINGS I --
VA lo►J tL. 2.5 _
4975
6/12
4970
7/12
4965
4960
SWA
NA
4955
4950
A-10
EMPIRE LABORATORIES, INC.
/l/a
4975
4970
4965
4960
LOG OF BORINGS
I o•ZZ r0 23
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A-9
EMPIRE LABORATORIES, INC.
LOG OF BORINGS
tj.,-.,. l0 de>.19
4975
12
4970
-�-
9/1
UFA
A,965
6/12
Wv
,960
14/12
4952
14
4945 V.
/
1.7
4940 li:
4935
4930
m
m
m
50/1
:m .• :••
T.
Zo
4975
4970
4965
4960
4955
LOG OF BORINGS
'
MA
-�-
�-
PAN
WIFE
m
A-7
EMPIRE LABORATORIES, INC.
4975
4970
4965
4960
4955
4950
LOG OF BORINGS
PA
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fQ�
NAM
--I�-V
WA�
[
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EPA
WIAM
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A-6
EMPIRE LABORATORIES. INC.
miow!
4975
4970
4965
4961
LOG
Nc S �•
OF BORINGS
�.?
�•8
WAR
WAA
4958
4957
4952
WA
WA
4947
4942
4941
mm
4937
4936
4932
m
FOR
4931
4927
4926
4923
4921
4917
A-5
EMPIRE LABORATORIES, INC.
�rwriw�
WE•
o�
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4975
4970
4965
4960
4956
4953
4951
4948
4947
4942
4936
4932
4931
4928
4927
4925
4922
4921
4917
LOG OF BORINGS
�—
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A
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A-4
EMPIRE LABORATORIES, INC.
KEY TO BORING LOGS
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GRANITE
SANDY SILTY
CLAY ❑
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SHELBY TUBE SAMPLE
STANDARD PENETRATION DRIVE SAMPLER
15 TO .
WATER TABLE
17 DAYS AFTER -DRILLING
C
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HOLECAVED
5/12 Indicates
that 5 blows
of a 140 pound hammer falling
30 inches was required to penetrate 12 inches.
A-3
EMPIRE LABORATORIES. INC
TEST BORING LOCATION PLAN
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A-2
EMPIRE LABORATORIES, INC,
APPENDIX A.
to aid in carrying out the plans and specifications as originally
contemplated. it is recommended that Empire Laboratories, Inc. be
retained to perform continuous construction review during the excavation
and foundation phases of the work. Empire Laboratories, Inc. assumes no
responsibility for compliance with the recommendations Included in this
report unless they have been retained to perform adequate on -site con-
struction review during the course of construction.
As.
(3) Gutters and downspouts should be designed to carry roof
runoff water well beyond the backf111 area.
(4) Footing sizes should be proportioned to equalize the unit
loads applied to the soil and thus minimize differential
settlements.
(5) It is recommended that all compaction requirements specified
herein be verified in the field with density tests performed
under the direction of the geotechnical engineer.
(6) It is recommended that a registered professional engineer
design the foundations using the recommendations presented in
this report.
GENERAL CWWS
This report has been prepared to aid in the evaluation of the
property and to assist the architect and/or engineer in the design of
this project. In the event that any changes in the design of the
structures or their locations are planned,, the conclusions and recom-
mendations contained in this report will not be considered valid unless
said changes are reviewed and conclusions of this report modified or
approved in writing by Empire Laboratories, Inc., the soils engineer of
record.
Every effort was made to provide comprehensive site coverage
through careful locations of the test borings, while keeping the site
investigation economically feasible. Variations in soil and groundwater
conditions between test borings may be encountered during construction.
In order to permit correlation between the reported subsurface con-
ditions and the actual conditions encountered during construction and j
0 a
The base course should be placed on the subgrade at or near optimum
moisture and compacted to at least ninety-five percent (95%) of Standard
Proctor Density ASTM 0 698-70. (See Appendix C.) It is important that
the base course be shaped to grade so that proper drainage of the
parking area is obtained.
The asphaltic concrete should meet City of Fort Collins Specifi-
cations or equivalent and be placed in accordance with those specifi-
cations.
We recommend that all light standards installed in the parking
areas be supported on straight -shaft drilled piers and bearing in the
near surface natural soils or compacted fill placed as recommended. The
and bearing pressure of the piers should not exceed one thousand (1000)
pounds per square foot. The ultimate passive resistance of the soil at
depth Z below finished grade should be computed using the equation Pp =
170Z + 1200 pounds per square foot. The passive pressure should be used
as the design criterion for resisting lateral forces and overturning
moments developed on the pier.
GENERAL RECOMMENDATIONS
(1) Laboratory tests indicate that water soluble sulfates in the
rear surface soils are negligible and a Type I cement may be
used in all concrete exposed to the subsoils. Water soluble
sulfates in the groundwater are positive. A Type II cement
should be used if the drilled pier alternative is selected.
All slabs on grade subjected to de-icing chemicals should be
composed of a more durable concrete using a Type II cement
with low water -cement ratios and higher air content.
(2) Finished grade should be sloped away from the structures on
all sides to give positive drainage. Five percent (5S) for
the first five (5) feet away from the structures is the sug-
gested slope.
Parking Area
Preparation to proposed parking subgrade elevation should be
accomplished as discussed in the "Site trading" section of this report.
Finished grades in the drive and parking areas should be a minimum of
three (3) feet above groundwater levels encountered in this Investi-
gation. AASHTO classifications of the material forming pavement sub -
grade are A-6 and A-7-6 with group indexes of 10 to 17. Based upon a
group index of 13, the following pavement thicknesses are recommended.
Parking Areas Drive Areas
Select Subbase --- 4"
Select Base Course 6" 6N
Asphaltic Concrete 2..0 2=
Total Pavement Thickness 8" 12"
The base course overlying the subgrade should consist of a hard,
durable, crushed rock or stone and filler and should have a minimum
C.B.R. value of 80. The composite base course material should be free
from vegetable matter and lumps or balls of clay and should meet the
Colorado Department of Highways Specifications Class 6 Aggregate Base
Course which follows:
Sieve Size % Passing
3/40 100
#4 30-65
48 25-65
#200 3-12
Liquid Limit - 30 Maximus
Plasticity Index - 6 Maximum
a
Basement and Retaining bulls
The on -site brown silty clay and more granular sandy silty clay can
be used for backfill against basement walls and cantilevered retaining
walls three (3) feet or less in height. The clay backfill should be
placed in horizontal lifts at optimum moisture content and compacted to
at least ninety-five percent (96%) of Standard Proctor Density ASTM D
698,70. (See Appendix C.) The walls should be designed using a hydro-
static pressure distribution and an equivalent fluid pressure of the
clay backfill of fifty (50) pounds per square foot per foot height of
wall.
Cantilevered retaining walls over three (3) feet in height should
be backfilled with an approved free draining granular material to
within one and one-half (11i) to two (2) feet of the top of the wall.
The granular backfill should be compacted to at least seventy-five
percent (75%) of Relative Density ASTM 0 2049-69. The retaining walls
should be designed using a hydrostatic pressure distribution and an
equivalent fluid weight of backfill of forty (40) pounds per square foot
per foot height of wall. The granular backfill should be overlain with
an untreated building paper or straw to prevent the overlying backfill
from clogging the granular material. The upper one and one-half (14) to
two (2) feet of the backfill behind these retaining walls should consist
of a relatively impervious clay material. The clay backfill should be
compacted to a minims of ninety-five percent (95%) of Standard Proctor
Density ASTH D 698-70. Weep holes should be provided in all retaining
walls to minimize hydrostatic pressure behind the walls. Positive
drainage should be provide away from the top of the wall to prevent
ponding of water in the area behind the wall. The maximum toe pressure
of cantilevered retaining walls should not exceed one thousand (1000)
pounds per square foot.
-11-
entering the system, it is recommended that a clay backf111 be placed
over the system and compacted at or near optimum moisture content to at
least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-
70. (See Appendix C.) The perimeter foundation drain should connect to
existing or proposed storm severs or the detention basin to be excavated
in the southeast corner of the site.
As a part of the dewatering systems slabs on grade constructed
below elevation 4769.0 should be underlain by a minimum of twelve (12)
inches of clean, graded gravel from three -fourths (3/4) to one and one-
half (1 1/2) inches in size. Water collecting in the gravel beneath the
stabs should be permitted access to the recommended perimeter foundation
drain.
Finished floors constructed above elevation 4769.0 should be under-
lain by a minimum of four (4) inches of clean gravel or crushed rock
free of fines. We suggest that the proposed gymnasium floor in the
multipurpose building be underlain by at least six (6) inches of crushed
gravel base course meeting the requirements of the Colorado Department
of Highways Class 6 Aggregate Base Course. The base course should be
placed at optimum moisture content and compacted to a minimum of ninety-
five percent (95%) of Standard Proctor Density ASTM D 69840. The
gravel base course and/or gravel will help to distribute floor loads and t
will act as a capillary break. Prior to placement of the base course
and/or gravel9 we recoeeend that the subgrade be prewet.
All slabs on grade should be designed for the Imposed loadings and
it is suggested that they be designed and constructed structurally
independent of all bearing members. To minimize and control shrinkage
cracks which develop in slabs on grade, we suggest that control joints
be placed every twenty (20) to twenty-five (25) feet and that the total
area contained within these joints be no greater than six hundred twenty-
five (625) square feet.
cohesion of five hundred (500) pounds per square foot. The passive
resistance at depth Z should be computed using the equation Pp a 170Z +
1200 pounds per square foot.
It is our opinion that performance of the structure supported by
any of the above foundation alternatives will be satisfactory. The
foundation system selected should be based upon cost studies and rela-
tive economics.
We request that when structural loads for remaining phases of the
construction become availables they be forwarded to us for our review
and analyses.
Basements and Slabs on Grade
Due to the groundwater levels encountered at the site, we end
that the basement finished floor be at least three (3) feet above
encountered water levels. Based upon plans provided to us indicating
basement areas, we recommend that the lower level be placed no lower
than elevation 4769.0. If the basement floor is below this elevation,
a complete dewatering system will be required. The dewatering system
should include perimeter foundation drains and free draining granular
material beneath the basement slab on grade.
For finished floors placed below elevation 4769.09 we recommend the
basement areas.be surrounded by a four -inch diameter, open -jointed or
perforated tile. The tile should be surrounded by clean, graded gravel
from three -fourths (3/4) to one and one-half (i 1/2) inches 1n size
extending from at least six (6) inches below the bottom of the tile to at
least elevation 4770.0 the full width of the trench. We recommend that
the drainage tile be placed at least eighteen (18) inches below the
basement finished floor elevation on a minimum grade of one -eighth (1/8)
inch per foot. The top of the free draining gravel backfill should be
covered with an untreated building paper to prevent the gravel from
becoming clogged by earth backfill. To prevent surface water from '
Footings bearing on a minimum of three (3) feet of compacted
granular fill may be designed for a maximum allowable pressure of two
thousand (2000) pounds per square foot under dead plus maxiaumm live
loads. Our analyses indicate that settlement of footings bearing on
structural fill will be approximately three -fourths (3/4) to one (1)
inch. The majority of this settlement will occur during construction.
An alternative to conventional shallow -depth footings would be to
support proposed structural loads on drilled piers and bearing in the
bedrock formation. We recommend that all piers be straight -shaft and
that they be drilled a minimum of three (3) feet into the firm siltstone
bedrock. Piers bearing in the bedrock as recommended may be designed
for a maximum allowable end bearing pressure of twenty thousand (20s000)
pounds per square foot. for that portion of the pier embedded into the
firm bedrock* a skin friction of two thousand (2000) pounds per square
foot may be used in determining allowable pier capacity. The antici-
pated settlement of the piers under the above maximum loading should be
negligible.
Due to the groundwater elevation at the site, temporary casing of
all pier holes will be required. To facilitate cleaning, dewatering,
and inspections we recommend that minimum twenty-four (24) inch diameter
piers be used.
It is strongly recommended that the geotechnical engineer be pre-
sent during the drilling operations to identify the firm bedrock stra-
tums confirm that proper penetration into the firm bedrock stratum is
obtained, ascertain that all drill holes are thoroughly cleaned and
dewatered prior to placement of any foundation concretes check all drill
holes to assure that they are plumb and of the proper diameter, and
insure proper placement of concrete and reinforcement.
The drilled piers should be designed to resist all induced lateral
forces. Ultimate passive resistance of the near -surface soils should be
computed using an angle of internal friction of ten (10) degrees and
I
tests should be taken daily to determine the degree of compaction being
attained and compliance with project specifications.
Foundations
Based upon the loads transmitted by the proposed construction and
the subsurface conditions encountered at the site$ we recommend that the
structures be supported by cmentional continuous or isolated spread
footings bearing in the natural undisturbed material. Prior to place-
ment of foundation concretee the bearing material should be carefully
examined by qualified geotechnical personnel. All footings should bear
a minimum of twelve (12) inches below present grades with exterior
footings a minimum of thirty (30) inches below exterior finished grades
for frost protection. Footings bearing in the above recommended depths
may be designed for a maximum allowable soil bearing pressure of one
thousand (1000) pounds per square foot under dead plus maximum live
loads.
Based upon the structural load information provided to us for the
Phase I construction and the results of laboratory tests and analyses,
we anticipate that settlement of footings designed and constructed as
recommended above will be approximately one-half (is) to one (1) inch.
We anticipate that the majority of this settlement will occur during
construction.
The allowable soil bearing pressure for footings at the upper level
can be improved by limited excavation and replacement with structural
fill. Due to the groundwater table, over excavation and replacement
below basement footings is not feasible.
If this alternative is selected, we recommend that a minimum of
three (3) feet of compacted pit -run sand and gravel be placed beneath
upper level footings. The sand and gravel fill should extend laterally
at least two (2) times the footing width. The approved pit -run should
be placed at optimum moisture content and compacted to a minima of one
hundred percent (100%) of Standard Proctor Density ASTM D 698-70. In -
place density tests should be performed to determine the degree of
compaction being attained.
All cuts and fills in the proposed detention basin area should be
placed on slopes no steeper than 3:1. All cut areas in the detention
pond should be scarified a minimum, of eight (8) inches and compacted at
two percent (2%) wet of optimum moisture to at least ninety-five percent
(95%) of Standard Proctor Density ASTM D 698-70. Fill placed in the
detention pond should consist of the on -site brown silty clay and should
be placed in accordance with the above recommendations. To minimize
erosion, the slopes and bottom of the basin should be seeded. All pipes
or apetures through the detention basin should be surrounded by a mini-
mum of two (2) feet of the upper brown silty clay compacted to a minimum
of one hundred percent (100%) of Standard Proctor Density ASTM 0 698-70.
Water was encountered in Boring 25 drilled in the proposed detention
pond area at a depth of five (5) feet below present grades. Temporary
dewatering of the pond area will be required if excavation extends below
the water cable.
Temporary cuts for installation of utilities will be stable on 1:1
or flatter slopes. If excavations extend below the water table, flatter
slopes and/or shoring may be required for stability. Utility exca-
vations extending below the water table should be dewatered during the
excavation, installation, and backfilling phases of the construction.
All backfill placed in utility trenches in open and planted areas
should be compacted in uniform lifts at optimum moisture to at least
ninety percent (90%) of Standard Proctor Density ASTM D 698-70 the full
depth of the trench. The upper four (4) feet of backfill placed in
utility trenches under slabs and paved areas should be compacted at or
near optimum moisture to at least ninety-five percent (95%) of Standard
Proctor Density ASTM D 698-70, and the lower portion of these trenches
should be compacted to at least ninety percent (90%) of Standard Proctor
Density ASTM 0 698-70.
Qualified geotechnical personnel should be present during all
phases of earthwork to observe stripping of the topsoil. scarification
of the subgrade, and placement and compaction of fill. In -place density
areas are presently planned in the southeast,portion of the educational
facility and in the south portion of the multipurpose area. A recre-
ation field will be constructed east of the proposed church facility.
Parking areas will be provided along the west, south, and east property
lines. A small detention basin will be excavated in the southeast
corner of the site.
. We understand that the first phase of construction will include the
multipurpose portion of the proposed facility. Anticipated wall loads
for this portion of the structure will be approximately 6.5 kips per
foot. Typical interior column loads will be about 70 kips with exterior
column loads approximately 40 kips.
The following are our recommendations for design and construction
of the proposed facility based upon plans submitted to us and influenced
by the subsurface conditions encountered in the test borings.
Site Grading
The upper six (6) inches of all topsoil should be stripped in
proposed cut and fill areas and in building and pavement areas which
will remain at present grades.. The topsoil can be stockpiled on the
site and used for final grading outside of building and pavement areas.
At cut subgrade elevation and in areas to receive fill, the upper six
(6) inches of the subgrade should.be scarified and recompacted at or.
near optimum moisture content to a minimum of ninety percent (90t) of
Standard Proctor Density ASTM D 698-70. (See Appendix C.)
The on -site brown silty clay and more granular red sandy silty clay
are suitable for fill in proposed building and pavement areas. Any
additional off -site fill required should be a material approved by the
geotechnical engineer. We recommend that all fill be placed in hori-
zontal six (6) to eight (8) inch lifts at optimum moisture content and
compacted to a minimum of ninety-five percent (95%) of Standard Proctor
Density ASTM D 69840.
1< .
(4) Sandy Silty Clay with Fine Gravel: In Borings 3, 5, and 17,
the red sandy silty clay is underlain by a brown sandy silty
clay with fine gravel. This alluvial soil represents a
different depositional period in the geologic history of the
site. Thin seams of fine sand and silt were also encountered
within the brown sandy silty clay. The brown sandy silty clay
Is stiff and has moderate shear strength and bearing quali-
ties.
(5) Siltstone Bedrock: The surface of siltstone bedrock was
encountered at thirty-seven (37) to fifty-three (53) feet
below present grades. The upper one (1) to two (2) feet of
the bedrock formation 1s weathered. The underlying siltstone
is hard and has very good shear strength and bearing quali-
ties.
(6) Groundwater: No water was encountered in Borings 20, 21. 22,
23. 26, and 27. dater was encountered in the remaining
borings to depths five (5) to eleven (11) feet below present
grades. Within the proposed building area, the groundwater
table varied between approximate elevations 4763.0 and 4766.0.
The elevations at which water was encountered indicate a
slight gradient to the south and east. Groundwater levels at
the site will fluctuate with seasonal variations and con-
ditions.
ANALYSIS AND RECOMMENDATIONS
Plans submitted to us indicate the proposed First Christian Church
facilities will include a sanctuary and various administration, edu-
cation, and multipurpose structures. The majority of the structures
will be masonry construction with conventional slabs on grade. Basement
(1) Topsoil: The thickness of topsoil at test boring locations
varies from approximately six (6) to twelve (12) inches. The
upper six (6) inches of the topsoil have been penetrated by
root growth and organic utter and are not suitable for foun-
dation bearing or backfill material.
(2) Silty Clay: Brown silty clay underlies the topsoil and ex-
tends to approximate depths six (6) to eight and one-half (81%)
feet below present grades. The very near surface silty clay
is dry and medium stiff to stiff 1n consistency. With in-
creasing penetration into this stratum, the soil becomes more
moist and softer. In its natural, undisturbed condition, the
brown silty clay exhibits low to moderate shear strength and
bearing qualities. The drier near -surface portions of this
stratum exhibit minor swell potential.
(3) Sandy Silty Clay: Tan and predominantly red sandy silty clay
underlies the brown silty clay and extends to depths thirty-
three (33) to forty-nine (49) feet below present grades. This
material 1s heterogeneous, the percentages of sand, silt and
clay comprising the soil varying with location and depth.
Within this stratum thin seams and layers of silty and clayey
sand with some fine gravel were also encountered. On the test
boring logs. we have indicated predominant zones of the sand
and fine gravel. The sandy silty clay is typically very moist
and soft. In situ, the soil has low shear strength and bear-
ing characteristics..
SITE LOCATION AND DESCRIPTION
The project site 1s located at the southeast corner of Drake Road
and Lemoy Avenue in southeast Fort Collins. Colorado. More specifi-
cally, the site may be described as a tract of land situate in the
northwest 4 of Section 30, Township 7 North, Range 68 West of the Sixth
Prime Meridian, Fort Collins, Colorado.
The site is presently an open area being used for agricultural
purposes. At the time of our investigation. the northwest corner had
been disced. The remainder of the property was in alfalfa. Several
small irrigation ditches traverse the property. The site slopes gently
to the south and east. At the northwest corner of the property. Drake
Road and Lemay Avenue are approximately three (3) to four (4) feet below
the general site elevation. A shopping center is presently under con-
struction immediately west of the property. Parkwood Lake is located
immediately north and residential areas border the property on the east
and south.
LABORATORY TESTS AND EXAMINATIONS
Representative samples recovered In the test borings were selected
for tests in the laboratory to determine their physical characteristics
and engineering properties. Included In the test program were natural
moisture content, water soluble sulfates, Atterberg limits. dry density,
unconfined compressive strength, swell potential, and consolidation
potential. Laboratory test results are summarized in Appendix B.
SOIL AND GROUNDWATER CONDITIONS
The subsurface conditions encountered to the test borings are con-
sistent with our previous experience on the site and in the areas Im-
mediately adjacent. The following are the characteristics of the
primary soil strata encountered at the site.
REPORT
OF A
GEOTECHNICAL INVESTIGATION
SCOPE
This report presents the results of a geotechnical investigation
prepared for the proposed First Christian Church to be constructed at
the southeast corner of Drake Road and Lemay Avenue in Fort Collins,
Colorado. The investigation included test borings, laboratory testing,
engineering evaluationo and preparation of this report.
The purposes of the investigation were to determine subsurface
conditions at the site and to provide recommendations for development of
the site as influenced by the subsurface conditions encountered.
SITE INVESTIGATION
Twenty-seven (27) test borings were drilled at the site on Septem-
ber 24, 259 and 26, 1979. Locations of the test borings are shown on
the Test Boring Location Plan included in Appendix A.
The borings were advanced with continuous -flight augers to depths
nine (9) to sixty-five (65) feet below present grades. Samples were
recovered with two and one-half (Zvi) inch Shelby tubes and the standard
penetration sample technique. During drilling, a field engineer of
Empire Laboratories, Inc. was present and made a continuous visual
inspection of soils encountered. Logs prepared from the field logs are
Included in Appendix A of this report. Indicated on the logs are the
primary strata encountered, locations of samples, and groundwater con-
ditions.
Empire Laboratories, Inc.
MATERIALS AND FOUNDATION ENGINEERS
214 No. Howes Fort Collins, Colorado 80522
P.O. Box 429 (303) 484-0359
NovembeA 21, 1979
FZut Clw. AVA t Chauk
Board o6 Tauateea
608 East VAake Road
Font CoWniii, Cotokado 80525
Attentiont MR. Rex Andeuon
BurLtding Commlttea chatunn
;e�JlJ;T1;E1
We cue pteaaed .to eubmU ota RepoAt o6 a Geoteehn&.at
pxeplauA 6oA the paopoaed FLut ChWtJan Chu&eh to be
.tn southe"t Font CotUna, Cotoxado.
Branch Offices
1242 Bramwood Place
Longmont, Colorado 80501
P.O. Box 1135
(303) 776-3921
3151 Nation Way
Cheyenne, Wyoming 82001
P.O. Box 10076
(307) 632.9224
Tnulutj4a.tton
conatiiudw
The eub4ux6aee eondWom xeveated by WA •inveatlgation axe auGtabte
6oit .the Zntended conetiu alon, p wuUed eonat ulwtion •i•e .in aeeoxdanee
with •the ucmendattone eontadned -in thIA xepoAt. The attached xepoAt
powente .the eubaux6aae eondtUone at Ae e•Lte and oua Alaw mnen&Wn4
Jet 6oundation dea•ign and con6tAuction•
We 4ppuz&te Chia oplpoxtmtty o6 conautting with• you on •thU pAoject.
T6 you have any queationa at•16 we can be o6 5untheA aaatatance, pteaae
cont4 t uae
Ve! ttul&j VOW",
EMPIRE LABMTORIES, INC.
1aaea E. VetdLe P.E.
GeoteehK&Ae Engdnem
Reutewed byt
Cheet" C. Sm4d, P.Ee
Pa"Ment
eat Gl44et A6aoclatea, MdUteeU
MEMBER OF CONSULTING ENGINEERS COUNCIL
15919
T
C 0'
TABLE OF CONTENTS
Table of Contents ..........................................
i
Letter of Transmittal ......................................
ii
Report .....................................................
1
Appendix A .................................................
A-1
Test Boring Location Plan ................................
A-2
Key to Borings ...........................................
A-3
Log of Borings ...........................................
A-4
Appendix 8.................................................
B-1
Consolidation Test Data ..................................
B-2
Sumary of Test Results ..................................
B-10
Appendix C.................................................
C-1
REPORT
OF A
GEOTECHNICAL INVESTIGATION
FOR
FIRST CHRISTIAN CHURCH
FORT COLLINS, COLORADO
PROJECT NO, 3582-79
RE: PROPOSED FIRST CHRISTIAN CHURCH
FORT COLLINS. COLORADO
BY
EMIPIRE LABORATORIES, INC-
214 NORTH HOWES STREET
FORT COLLINS, COLORADO
80521