HomeMy WebLinkAboutRe: weather station tower � ������� o NV RO M NTAL
EIiGINE�R�1G ����� �� �,. ,� �, , ,,. r a---, EOTECHNICAL
TEs�riric, Ir�c. �� y , � �IATERIALS
� "� " ' � o FORENSICS
July 7, 2017 Reviewed for Code
Compliance City of Orono
Mr. Daniel Bovitz Dat@ / �
Hennepin County Emergency Management
1600 Prairie Drive Roviewer ry�
Medina, MN 55340
Re: Weather Station Tower Support
Orono, MN
AET Project No. 09-00552
Dear Mr. Bovitz:
American Engineering Testing, Inc. (AET) has completed our services related to the proposed
weather station tower in Orono, MN. The scope of our services was presented in our proposal
dated May 25, 2017, and was limited to the following:
1. Perform site documentation and analysis of soil conditions at the tower location.
2. Perform an in situ load test of a screw anchor installed as it will be for anchoring the guy
wires of the actual tower.
3. Prepare a report with the results of our testing and analysis of the soil conditions at the
tower location.
Our services were performed in accordance with the terms of CSA Agreement A152997 and
P.O.No. 309666.
Proiect Information
Hennepin County (County) is planning on erecting a weather station tower in Orono, MN. The
tower will be a Campbell Scientific, Inc. (Campbell) UT30 model that will stand 30 feet high
with three guy wires providing lateral support.
The County will follow the installation procedures outlined by Campbell for the UT30 tower
except that they will deviate as follows:
l. The tower base will be placed on grade and anchored to the ground with four (4) steel
rods driven to a depth of 48 inches. The preparation of the subgrade below the base has
not been specified.
2. The guy wire anchors will be anchored into the ground using a galvanized steel, 54-inch
long earth screw anchor with a 4-inch diameter helix.
550 Cleveland Avenue North � Saint Paui, MN 55114
Phone(651) 659-9001 � (800) 972-6364 � Fax (651) 659-1379 � www.amengtest.com � AA/EEO
Hennepin County
� AET Project No. 09-00552
July 7, 2017 �'"' �"�`° '� �'' � �' �
Pa e2of4 `'���M,i`��i��
g
Analvsis Results
Review of Tower Support Svstem
The design of the tower structure and guy wire assembly (i.e. materials, connections, etc.) has
been engineered by Campbell and was not included in our scope of services.
Based on the requirements of ASCE-7 and the 2015 Minnesota Building Code, we estimate the
maximum tension in the guy wires with a 110 mile per hour wind speed will be approximately
990 pounds. Our analysis took into account ice formation on the tower. Refer to the Screw
Anchor Analysis section below for our opinion on the adequacy of the proposed screw anchor to
resist this load.
If concrete deadmen are used to anchor the tower and guy wires,the Campbell design installation
procedures are appropriate with the exception of the size of the guy wire deadman. We
recommend the concrete deadmen for the guy wire anchor be at least 27" x 27" x 27".
Site Soils
We completed a hand auger soil boring at the tower location. A Subsurface Boring Log is
attached in the appendix. A summary of the soils encountered is provided below:
• The soil boring encountered approximately 3 inches of dark brown silty sand topsoil. Fill
consisting of sandy lean clay was encountered beneath the topsoil and extended to a
depth of approximately 4.5 feet. The underlying soil consisted of a 3 foot layer of organic
swamp deposit over stiff sandy lean clay that extended to the boring termination depth of
approximately 9.5 feet.
Screw Anchar Anal.�
We completed dynamic cone penetrometer (DCP) testing in 6 inch increments from 4 to 9.5 feet
of the boring. Based on a correlation to DCP blows, we estimated the standard penetration
resistance (N-value) at the DCP locations. Using the estimated N-value, we determined the uplift
resistance of the soil with installation of a 4-inch diameter screw anchor. Due to the uncontrolled
nature of the fill soils in the upper region of our soil boring, our analysis indicates the capacity of
the screw anchor to resist pullout from a 990-pound force from the guy wires is indeterminate.
Our analysis includes a minimum factor safety of two.
Given the marginal site soils, an in situ load test of a screw anchor installed as it will be in
service was authorized by the County to document the performance of the anchor under load.
Refer to the In Situ Load Test section below for the results. These services were in addition to
the original scope proposed in our proposal dated May 25, 2017.
In Situ Load Test
The load test was performed on a screw anchor installed by the County prior to our arrival on
site. The location coincided with the approximate center of the proposed tower. The anchor was
installed in a vertical orientation with the center of the eye approximately 4 inches above grade.
The vertical orientation is counter to the Campbell UT20 and UT30 Universal Towers
Hennepin County �����E�
AET Project No. 09-00552
July 7, 2017
Page 3 of 4
Instruction Manual, Section 7.1.3.2 UTDUK Duckbill Guy Anchor, which requires the anchor to
be installed at the same angle as the guy wires (60 degrees from horizontal). Though the County
is using a screw anchor rather than the duckbill anchor, the recommended installation angle is the
same. Mr. Kelly Fisher of Hennepin County indicated previous weather station towers were all
installed with the anchors vertical and requested we proceed with the load test on the vertical
anchor.
The load was applied to the screw anchor with a chain attached to a Bobcat skid-steer loader.
Refer to the photograph in the appendix for test set up. The minimum test load was 1,500
pounds which is approximately 1.5 times the design guy wire load of 990 pounds. A stringline
was used to measure the horizontal and vertical movement of the anchor during and after the test.
The test load varied between 1,500 and 2,100 pounds during the test and was held for 10 minutes
prior to releasing the load.
Measurements indicate the anchor moved 2.75 inches horizontally and 1.9 inches vertically due
to the applied load on the anchor. Although the loading did not cause failure of the anchor, a
significant wind event will likely cause additional movement of the anchor and slackening of the
guy wires.
Frost Heave
The soils present on the site have a high frost heave potential. If lenses of silt are present within
the soil profile, about 1 to 3 inches of frost heave may occur. Frost penetration in clay soils
would be approximately 4 feet during an average winter, and 5 feet during a severe winter.
Comparable frost penetration for sand soils would be about 6 feet during an average winter, and
7 feet during a severe winter. These frost penetration depths assume there is no snow cover
providing insulation to the underlying ground.
Frost heave is a cumulative process with the heaved anchor or tower base rods not returning to
its pre-heaved state when thawing occurs. Consequently, the anchor or rod slowly gets jacked out
of the ground each year frost heave occurs.
Based on the length of the proposed helical anchors, about 4.5 feet of embedment is anticipated
below the ground surface. Based on this, some frost heaving of the helical anchors and tower
base rods may occur. If heaving does occur, it will tend to reduce the tension in the guy wires.
We recommend that the tension in the guy wires be checked on a periodic basis to look for signs
of frost movement.
Other Recommendations
We recommend at least quarterly observation of the guy wires, anchoring devices and tower base
in order to detect possible movement due to frost action or settlement. An observation should
also be completed after a significant wind event. If minor movement of the anchors or the tower
base is noted, adjustments to the guy wire tension should be made. If cumulative frost heave
movement is significant, the anchors should be reinstalled to their pre-heave depth.
�d..+�t�Y�°�i'��.d
, Hennepin County
AET Project No. 09-00552
July 7, 2017
Page 4 of 4
Preparation of the tower base subgrade should involve removal of any vegetation and any
organic soil with over 3 percent organic content by weight from within the tower base area and a
minimum 3-foot oversize area. Additional excavation should be completed as necessary to allow
placement of a minimum of 6 inches of Class 2 aggregate base.
Prior to placement of the aggregate base, the exposed subgrade should be surface-compacted
with a minimum of four passes with a vibratory compactor having a minirnum dynamic force of
15,000 pounds. The aggregate base should then be placed and compacted to a firm, non-yielding
condition.
Procedures
The hand auger boring was drilled with a 1'/2-inch diameter hand auger. The borings were
advanced in 4- to 6-inch increments to depth of 9.5 feet below the ground surface. The auger was
withdrawn from the borehole after each advancement to obtain soil cuttings.
The dynamic cone penetrometer (DCP) tests were completed in general accordance with ASTM
International Standard Test Method D6951.
Remarks
It has been a pleasure assisting you with this project. Please contact us if you have any questions
regarding our results or this report.
Sincerely,
American Engineering esting, Inc.
. ���
Daniel J. Larso P Loren Braun, PE
Principal Enginee Principal Engineer
MN Lic. No. 19649
Phone: 651-659-1337
dlarson@amengtest.com
Attachments: Subsurface Boring Logs
Photograph of In Situ Load Test Set Up
,aMEi�caN �������`�� �.��
. � ENGINEERING SUBSURFACE BORING LOG
� TESTING, INC.
AET No: 09-00552 Log of Boring No. B-1 (p. 1 of 1)
Project: Orono Weather Station Tower;
D�� Surface Elevation GEOLOGY N MC SAMPLE REC ��&LABORATORY T'ESTS
FEET MATERIAL DESCRIPTION �E IN• WC DEN LL PL o-#20
FILL,mostly silty sand,trace roots,dark brown FILL
1 FILL,mostly sandy lean clay,brown to gray M DS
Z FILL,mixture of silty sand and clayey sand with
3 gravel,dark brown M DS
4
ORGANIC SILTY SAND,trace wood chips at 4* � DS
5 top 6",dark brown to black,moist to wet(SM) 2* M DS
6
2* W DS
7
SANDY LEAN CLAY,brown with dark brown FINE 3* W DS
8 mottling,wet(CL) �-L�N�
21* W DS
9
9/6" W DS
END OF BORING
*N-value estimated from DCP readings
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a DATE TIME SAMPLED CASING CAVE-IN DRII,LING WATER �ATTACHED
� O-9%z' 3.25" HSA DEPTH DEP'I'H DEPTH FLUID LEVEL LEVEL
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' AET PROJECT NO.09-00552
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Photo 1: In situ load test set-up. I
AMER[CAN CONSULTANTS
ENGINEERING x^�p !^'� 1►, �►. �►� ��� •ENVIRONMENTAL
TESTiNG� INC. •MATERIALSCAL
� •FORENSICS
May 31, 2016
City of Plymouth
Attn: Bob Rood
Re: Weather Station Tower
Hennepin County Emergency Management
AET Project No. OS-06764
Dear Mr. Rood:
American Engineering Testing, Inc. (AET)has reviewed the tower support system Hennepin
County plans to use to install a weather station tower at the Adult Corrections Facility(1145
Shenandoah Lane North,Plymouth MN 55447). The tower will be manufactured by Campbell
Scientific,Inc., Model UT30.
The tower support system will consist of one of two types:
1. Concrete deadmen; or
2. 54 inch steel screw anchors
AET has reviewed the general soil conditions at the site to determine the suitability of the
proposed tower support system.We have also performed an analysis of the support system to
verify its capacity to resist the design wind load.
Based on the insta.11ation information supplied by the County,our analysis,and the
recommendations made in our report dated May 24, 20I6,the tower support system,as
proposed,is capable of resisting a design wind load of 110 miles per hour.
Please contact us if you have any questions regarding this letter.
Sincerely,
'r.sn Engineering T Inc.
Daniel J. Larson, P
Principal Engineer
MN License No. 19649
Phone: 651-659-1337
d 1 ars on Ca�am eng t est.c om
Cc: Daniel Bovitz, Hennepin County
550 Cleveland Avenue North�Seint Paul,MN 55114
Phone(651)659-9001 �(800)972-6364�Fax(851)859-1379�www.amengtest.com�AAIEEO
��}"��;j�[{;,�`� CONSULTANTS
L�,�����E��� � ENVIRONMENTAL
��'+ � GEOTECHNICAL
l ESTIh�yy �tiC. MATERIALS
� FORENSICS
May 24, 2016
Mr. Daniel Bovitz
Hennepin County Emergency Management
1600 Prairie Drive
Medina, MN 55340
Re: Weather Station Tower Support
Various Sites
AET Project No. OS-06764
Dear Mr. Bovitz:
American Engineering Testing, Inc. (AET) has completed our services related to construction of
weather station towers at various sites in Hennepin County(County). The scope of our services
was presented in our proposal dated April 5, 2016, and was limited to the following:
1. Review the design of the proposed tower support system.
2. Perform site documentation and evaluation of soil conditions at five tower locations.
3. Prepare a report with our opinion on the adequacy of the proposed tower support system.
Our services were performed in accordance with the terms of CSA Agreement A152997 and
P.O.No. HNCTY-26262G.
Proiect Information
The County is planning on erecting several weather station towers around the county. The
towers will all be Campbell Scientific, Inc. (Campbell) UT30 models which will stand 30 feet
high with three (3) guy wires providing lateral support.
The County will follow the installation procedures outlined by Campbell for the UT30 tower
except that, in some locations,they may deviate as follows:
1. The tower base will be placed on grade and anchored to the ground with four(4) steel
rods driven to a depth of 48". The preparation of the subgrade below the base has not
been specified.
2. The guy wire anchors will be anchored into the ground using a galvanized steel, 54-inch
earth screw anchor with a 4-inch diameter helix.
550 Cleveland Avenue North�Saint Paul,MN 55114
Phone(651)659-9001 �(800)972-6364�Fax(651)659-1379�www.amengtest.com�AA/EEO
Hennepin County � _,
AET Project No. OS-06764 ��� -;�, ��-�.,� ��,,� ������
May 24, 2016
Page 2 of 5
Analvsis Results
Review of Tower Support S, s�
A review of the guy wire tower support system was performed based on a design wind of I 10
miles per hour. As noted above, we assume the County will follow the installation instructions
included in the Campbell Scientific Instruction Manual for UT30 Tower-based Weather Stations
with the listed exceptions. The design of the tower structure and guy wire assembly (i.e.
materials, connections, etc.) has been engineered by Campbell and was not included in our scope
of services.
Based on the requirements of ASCE-7 and the 2015 Minnesota Building Code, we estimate the
maximum tension in the guy wires with a 110 mile per hour wind will be approximately 990
pounds. Our analysis took into account ice formation on the tower. Refer to the Helical Anchor
Analysis section below for our opinion on the adequacy of the proposed screw anchor to resist
this load.
If concrete deadmen are used to anchor the tower and guy wires,the Campbell design installation
procedures are appropriate with the exception of the size of the guy wire deadman. We
recommend the concrete deadmen for the guy wire anchor be at least 27" x 27" x 27". Refer to
the Deadman Anchor Analysis section below for our recommendations regarding uplift
resistance and backfilling of the deadmen.
Site Soils
We completed a hand auger soil boring at each of the tower locations. Subsurface Boring Logs
for each of the five locations are attached in the appendix. A summary of the soils encountered at
each of the five locations is provided beiow:
• 6 Mile Creek Road
The soil boring encountered approximately 1 '/2 feet of dark brown silt topsoil. Fine
alluvial lean clay with sand was encountered beneath the topsoil and extended to a depth
of approximately 6 feet. The underlying soil consisted of a thin layer of coarse sand over
clayey sand that extended to the boring termination depth of approximately 7 feet.
• Rolling Hills Drive
The soil boring encountered approximately 1 foot of dark brown lean clay topsoil over
fine alluvial lean clay with sand extending to a depth of approximately 2 %2 feet, and then
clayey sand extending to the boring termination depth of approximately 7 feet.
• Electric Drive
The soil boring encountered approximately 1 foot of dark brown lean clay topsoil over
lean clay with sand extending to the boring termination depth of approximately 7 feet.
• Crow Hassen Park Reserve
The soil boring encountered approximately 3 inches of dark brown silty sand topsoil over
silty sand extending to a depth of approximately 6 feet and then lean clay to the boring
termination depth of 7 feet.
, ��������
Hennepin County
AET Project No. OS-06764
May 24, 2016
Page 3 of 5
• Adult Correctional Facilitv
The soil boring encountered fill that extended to a depth of approximately 6 %z feet. The
fill consisted mostly of lean clay with gravel to a depth of 2 '/2 feet then lean clay with
sand to a depth of 5 feet, sandy lean clay with a trace of gravel to a depth of 6 feet and
clayey sand to a depth of approximately 6 'h feet. The boring terminated at a depth of 7
feet in sand that was fine to medium grained. It was not possible to determine if the sand
was natural soil or fill.
Helical Anchor Analysis
We completed a dynamic cone penetrometer (DCP) test at a depth of 6 feet in each of the
borings. Based on a correlation to DCP blows, we estimated the standard penetration resistance
(N-value) at the DCP locations. Using the estimated N-value, we determined the uplift resistance
of the soil with installation of a 4-inch diameter helical anchor. Our analysis indicates that
adequate capacity is available to resist pullout from a 990-pound force from the guy wires. Our
analysis includes a minimum factor of safety of two.
The test location at the Adult Correctional Facility encountered uncontrolled fill. Uncontrolled
fill is fill that appears to have been placed without regard to consistency or compaction effort.
Consequently, inadequate bearing capacity may occur at some of the anchor locations because of
the variability in the condition of the fill. As a result, deeper embedment of the anchors may be
required at this site. The capacity of the anchor will need to be verified at the time of placement
by measuring the torque required to install it.
Deadman Anchor Anal.�
We understand that concrete deadman anchors may be utilized at some of the towers. The size
and installation of the deadmen is specified in the Campbell Instruction Manual. For a deadman
anchor buried with compacted backfill and its top at grade (i.e. no soil overburden on the
anchor), we recommend assuming the resistance to uplift is equal to the weight of the concrete in
the anchor. Backfill around the deadman anchor should be compacted to a minimum of 95
percent of its maximum dry density based on the standard Proctor test (ASTM International,
Specification D698).
For wind uplift, which is a transient load, we recommend using a minimum factor of safety of
1.5 for the ratio between the calculated uplift resistance and the design uplift loads. For a 2'x 2'
x 2' deadman (as specified in the Campbell Instruction Manual), the weight would be
approximately 1,200 pounds which is 1.2 times the design uplift load. To achieve a 1.5 factor of
safety, a minimum 27" x 27" x 27" deadman should be used.
Frost Heave
The soils present on the five sites have a moderate to high frost heave potential. If lenses of silt
are present within the soil profile, about 1 to 3 inches of frost heave may occur. Frost penetration
in clay soils would be approximately 4 feet during an average winter, and 5 feet during a severe
winter. Comparable frost penetration for sand soils would be about 6 feet during an average
winter, and 7 feet during a severe winter. These frost penetration depths assume there is no snow
cover providing insulation to the underlying ground.
Hennepin County
AET Project No. OS-06764
May 24, 2016
Page 4 of 5
Frost heave is a cumulative process with the heaved anchor or tower base rods not returning to
its pre-heaved state when thawing occurs. Consequently, the anchor or rod slowly gets jacked out
of the ground each year frost heave occurs.
Based on the length and embedment angle of the proposed helical anchors, about 3.9 feet of
embedment is anticipated below the ground surface. Based on this, some frost heaving of the
helical anchors and tower base rods may occur. If heaving does occur, it will tend to reduce the
tension in the guy wires. We recommend that the tension in the guy wires be checked on a
periodic basis to look for signs of frost movement.
More substantial frost heave could occur with the concrete deadman anchors due to frost heaving
below the base of the deadman anchor and additional heave due to frost adhesion of the buried
portion of the deadman anchor. As previously indicated, up to 3 inches of heave could occur
during a severe winter. We anticipate that the potential frost heave of the tower base, if it is
placed on the existing soils, would be similar to the potential heave of the deadman anchors.
Heaving of the tower base would increase tension in the guy wires and could potentially cause
damage to the tower structure.
Other Recommendations
We recommend at least quarterly observation of the guy wires, anchoring devices and tower base
in arder to detect possible movement due to frost action or settlement. If minor movement of the
anchors or the tower base is noted, adjustments to the guy wire tension should be made. If
cumulative frost heave movement is significant, the anchors should be reinstalled to their pre-
heave depth.
Preparation of the tower base subgrade should involve removal of any vegetation and any
organic soil with over 3 percent organic content by weight from within the tower base area and a
minimum 3-foot oversize area. Additional excavation should be completed as necessary to allow
placement of a minimum of 6 inches of Class 2 aggregate base.
Prior to placement of the aggregate base, the exposed subgrade should be surface-compacted
with a minimum of four passes with a vibratory compactor having a minimum dynamic force of
15,000 pounds. The aggregate base should then be placed and compacted to a firm, non-yielding
condition.
Procedures
A hand auger boring was drilled at each site with a 1'/2-inch-diameter hand auger. The borings
were advanced in 4- to 6-inch increments to depth of 7 feet below the ground surface. The auger
was withdrawn from the borehole after each advancement to obtain soil cuttings.
The dynamic cone penetrometer (DCP) tests were completed in general accordance with ASTM
International Standard Test Method D6951.
Hennepin County � , � � ���� �"�� ��. � �
AET Project No. OS-06764
May 24, 2016
Page 5 of 5
Remarks
It has been a pleasure assisting you with this project. Please contact us if you have any questions
regarding our results or this report.
Sincerely,
American Engineering esting, Inc.
,��
. �..
Daniel J. Larso P Loren Braun, PE
Principal Enginee Principal Engineer
MN Lic. No. 19649
Phone: 651-659-1337
dlarson@amengte st.com
Attachments: Subsurface Boring Logs
AMERICAN , �"�m�"'
1 ENGINEERING SUBSURFACE BORING LOG
� TESTING, INC.
AET No; 05-06764 Log of Boring No. B-1 (p. 1 of 1)
Project: Hennepin County Weather Stations; Minnesota
D�TH Surface Elevation GEOLOGY N MC SAMPLE �.� FIELD&LABORATORY TESTS
FEET MATERIALDESCRIPTION TYPE iN. WC DEN LL PL o-#20
SILT,trace roots,dark brown,moist(ML) TOPSOIL M DS
1
LEAN CLAY WITH SAND,trace roots,brown FINE
(CL) ALLWIUM M DS .
2
3
4
M DS
5
15* �
6 SAND,medium to coarse grained,brown,wet '•�•:COARSE* —
(SP) MIXED
CLAYEY SAND,brown(SC) '� �Lw�� W DS
� END OF BORING *ALLWIUM
*N-value estimated fi•om DCP readings
Location: Minnetrista South, 6 Mile Creek Road
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" DEPTH: DRILLING METHOD WATER LEVEL MEASUREMENTS
W NOTE: REFER TO
a SAMPLED CASING CAVE-IN DRILLING WATER
� 0-7' HAB DATE TIME DEPTH DEPTH DEPTH FLUID LEVEL LEVEL T�ATTACHED
° 4/29/16 g.� SHEETS FOR AN
�
� EXPLANA'TION OF
� COMPLETED: 4/29/16 TERMINOLOGY ON
W DR: BJH LG: BJH Ri : HA THIS LOG
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03/2011 01-DHR-060
AMERICAN . , . � .
� ENGINEERING SUBSURFACE BORING LOG
� TEST`ING, INC.
AET No: OS-06764 Log of Boring No. B-2 (p. 1 of 1)
Project: Hennepin Couniy Weather Stations; Minnesota
DEPNTH Surface Elevation GEOLOGY N MC SAMPLE �C FIELD&LABORATORY TESTS
FEET MATERIAL DESCRIPTION �PE �' WC DEN LL PL o-#20
LEAN CLAY,trace roots,dark brown(CL) TOPSOIL M DS
1 LEAN CLAY WITH SAND,brown(CL) FINE M DS
ALLUVIUM
2 �
CLAYEY SAND,trace gravel,light brown(SC) � MIXED —
� ALLUVIUM M DS
3
4
5
� 19* W DS
6
� END OF BORING
*N-value estimated from DCP readings
Location: Minnehista North,Rolling Hills
Drive
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� , DATE TIME S DEPTHD DE TH C EPTH FLUID LEVEL LEVEL T�ATTACHED
0-7 HAB
^ 4/29/16 2,3 SHEETS FOR AN
� EXPLANATION OF
0
� G TERMINOLOGY ON
� COMPLETED: A/29/16
i
THIS LOG
Q DR: BJH L�: BJH �ti : HA
03/2011 O1-DHR-060
AMERICAN '� 4 '�-�-;��,
; �5�:��r �
� ENGINEERING SUBSURFACE BORING LOG
� TESTING, INC.
AET No: OS-06764 Log of Boring No. B-3 (p. 1 of 1)
Project: Hennepin County Weather Stations; Minnesota
D�TH Surface Elevation GEOLOGY N MC SAMPLE �� FIELD&LABORATORY TESTS
FEET MATERIAL DESCRIPTION �PE �' WC DEN LL PL o-#20
LEAN CLAY,h•ace roots,dark brown(CL) TOPSOIL M DS
1 LEAN CLAY WITH SAND, brown, laminations FINE
of inedium grained sand at 6'(CL) ALLUVIUM M DS
2
3
M DS
4
5
6 14* M
M DS
� END OF BORING
*N-value estimated from DCP readings
Location: Wright-Hennepin ElecU�ic,Electric
Drive
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� NOTE: REFER TO
W
� , DATE TIME S DEP H DEPTA CDEPTH FLUID LEVEL LEV�EL T�ATTACHED
0-7 HAB
� 4/29/16 None SI-IEETS FOK AN
� EXPLANATTON OF
0
� COMPLETED: 4/29/16 TERMINOLOGY ON
�� THIS LOG
Q DR: BJH LG: BJH Ri : HA
03/2011 O 1-DHR-060
AMERICAN ..�. .., , _
. � i ��,. .<_ ���....-F
1 ENGINEERING SUBSURFACE BORING LOG "
� TESTING, INC.
AET No: OS-06764 Log of Boring No. B-4 (p. l of 1)
Project: Hennepin County Weather Stations;Minnesota
DE�TH Surface Elevation GEOLOGY N. MC SAMPLE �C F[ELD&LABORATORY TES7'S
FEET MATERIAL DESCRIPTION �E �' WC DEN LL PL o-#20
SILT'Y SAND,ti�ace roots,dark brown(SM) : � TOPSOIL
SILTY SAND,fine grained,brown,moist to wet .• •�' COARSE
�. :� ALLWILJM
1 �SM� M DS
2
�
3
W DS
4
5
11* M DS
6 LEAN CLAY,brown(CL) � FINE
ALLUVILJM
M DS
� END OF BORI1vG
*N-value estimated from DCP readings
Location: Crow Hassen Park Preserve
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0-7 HAB
� 4/29116 2.� SHEETS FOR AN
�
� EXPLANATION OF
� COMI'LETED: 4/29/16 TERMINOLOGY ON
U
I
Q DR: BJH LG: BJH Ri : HA THIS LOG
03/2011 O1-DHR-060
�MERICAN � ��
� ENGINEERING SUBSURFACE BORING LOG
�� TESTING, INC.
AET No: OS-06764 Log of Boring No. B-5 (p. 1 of 1)
Project: Hennepin County Weather Stations; Minnesota
DEPTH Sucface Elevation GEOLOGY SAMI'LE �C FIELD&LABORATORY TESTS
FEET MATERIAL DESCRIPTION N MC TypE IN. WC DEN LL PL o-#20
FILL,mostly sandy lean clay with gravel,dark FILL
brown M DS
I
2
M DS
FILL,mostly lean clay with sand,h•ace gravel,
3 black
4
M DS
5 FILL,mostly sandy lean clay,trace gravel,
brown
20* M DS
6 FILL,mostly clayey sand with gravel,brown M DS
SAND,fine to medium grained,brown,moist '���: COARSE M DS
7 (SP)(possible fill) *
END OF BOWNG *oR FILL
*N-value estimated from DCP readings
Location: Adult Conectional Faciliiy
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� COMPLETED: 4/29/16 'I"ERNIINOLOGY ON
Q DR; BJH LG: BJH Rig: HA
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03/2011 01-DHR-060
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Resolution
Exhibit A
Site Layout Overview:
Land Use Area: 40 feet x 40 feet
Items to be put on land: 10 meter tower with guy wires, grounding probe, soil moisture probe,
soil temperature probe, rainfall sensor.
Items to be put on tower: wind speed,wind direction, pressure sensor, temperature probe, solar
radiation sensor, solar panel, datalogger, battery,relative humidity sensor, and wet bulb black
globe sensor.
Power: Solar Powered with Battery Backup
� Access tube tor
�� sod maisuxe �
w�,d saee� r —-' _—— — �
f,q � E 'fempe�aWfe F
♦ � under sod r
� \b f � i
� I I
4 I 1
'` �� l�r. ...J
t ���� RUbber '�
� empe�aRtx�e
� ddgrcs0 under par8�il
` o
�
i �.5 m.T/RH and 9 rn.T
3 m. {muEdWBtt st�ield)
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► �
� �
k �
i t
i �
�._______S m.--- -- -- ----3 m.--______.�
2 rn.wind speed�
�.7 m.
Trrpod mount for
pYranorneter ��g rod sat�r
� pa,r►�sred�aS�stuas
��B ++of sAoMts lb�dmrfiry
FyG.S. !']ass Yicw of a remotc station shawing ruin gauge aad soi!s�t�s relativt to the tawer.
� • _.f��1aI€ �y `'q ����r
11a.ni++�in�I�pecd c�h directirm
�3-tn��ittd a(ye�d' ! Ligltt»mg rtxd
9-m temgeran�rc`�.` �
Antenna W thr t:)klahvi��a La��
�nfarccm��t"tclecv[nr�eun�tiKm�Systcmo
Ro
sotar}�nr'I
�-m wind specd" }3,ammtnetric�rc�.sut'�:�
I.5-m tcm�r�surc&
dat�Ic�g�rr,hatre�;=.a�r�dio
rclatiti�c humidit}• `� � �'
i.i-m r��lar radiation
Rainfali
tA1lcr+hielc�nnt x3ua+r��►
Soi1 temgeratvrc ru;rit mc�isturr'
IS•.l0.�t)�`cm) C,a7und r�x1 t5.25,t�),75 cm}
Site locations will need to be chosen based on the following criteria:
Accessible be vehicle during all seasons.
Wind Speed and Wind Direction:
• Standard is 10 m above ground level with no obstructions within 300 m for anemometer
and vane exposure.
• Slope should be less than 17 degrees to avoid separation of flow, producing large eddies.
Solar Radiation:
• Site should be free of obstruction above the lane of the radiation sensing element.
• Important that no obstruction cast a shadow on a solar radiation sensor.
� � �..r�a,,,,.�`a' '�; .. x . .._. ..
• Slope of terrain should be less than five degrees to avoid having to consider aspect on
surface radiation measurements.
Temperature and Relative Humidity:
• To be compliant with existing observations and airport stations, temperature and RH
should be made at the standard height of 1.5 m.
Pressure:
• Sensors must be designed to minimize dynamic pressure.
Precipitation:
• Reduce the effects of wind by using a wind shield.
• Gage should be over level ground and surrounding objects should not be closer to the
gage than a distance equal to four times their height.
Soil Temperature and soil moisture
• Soil should be representative of the entire area.
• Standard depths for soil temperature measures are 5, 10, 20, 50, and 100 cm