Proposed Earthen Constructed Wetland CREP Wetland

IOWA MINNESOTA WISCONSIN

Factual Geotechnical Report:

Proposed Earthen Constructed Wetland CREP Wetland Flo941603B Section 3 – T95N – R16W St. Charles Township, Floyd County, Iowa CVT# 13244.18.IAM

Prepared for:

Mr. Nathan Anderson, PE WHKS & Co.

Certification:

I hereby certify that this report was prepared by me or

under my direct supervision, and that I am a duly

Licensed Professional Engineer under the laws of the

State of Iowa.

Matthew J. Reisdorfer, PE

Geotechnical Engineer

License Number 22234

Date: July 19, 2018

M i n n e s o t a I o w a W i s c o n s i n

TABLE OF CONTENTS

A. Introduction .......................................................................................................................2

A.1. Purpose ................................................................................................................................... 2

A.2. Scope ...................................................................................................................................... 2

A.3. Boring Locations and Elevation ................................................................................................. 2

A.4. Geologic Background ............................................................................................................... 3

B. Subsurface Data .................................................................................................................3

B.1. Stratification ............................................................................................................................ 3

B.2. Penetration Test Results........................................................................................................... 4

B.3. Groundwater Data ................................................................................................................... 5

C. Level of Care .......................................................................................................................5

Appendix .................................................................................................................................6

Soil Boring Location Sketch

Log of Boring # 2, 4-8

Legend to Soil Description

CREP Wetland Flo941603B July 19, 2018

Project: 13244.18.IAM Page - 2


Chosen Valley Testing, Inc. Geotechnical Engineering and Testing • 421 North Georgia Avenue • Mason City, IA 50401 • Telephone (641) 201-1050 • [email protected]

Mr. Nathan Anderson, PE July 19, 2018

WHKS & Co

2905 South Broadway

Rochester, MN 55904

[email protected]

Re: Proposal for Factual Geotechnical Evaluation

Proposed Earthen Constructed Wetland

CREP Wetland Flo941603B

Section 3 – T95N – R16W

St. Charles Township, Floyd County, Iowa

CVT Proposal Number: 13244.18.IAM

Dear Mr. Anderson:

This factual report was prepared to assist planning for the proposed earthen constructed wetland in St. Charles

Township, Floyd County, Iowa. Our services were authorized by Mr. Nathan Anderson of WHKS.

A. Introduction

The intent of this report is to present our results to the client in the same logical sequence that led us to arrive

at the opinions and recommendations expressed. Since our services must often be completed before the design,

assumptions are sometimes needed to prepare a proper evaluation and to analyze the data. A complete and

thorough review of this entire document, including the assumptions and the appendices, should be undertaken

immediately upon receipt.

A.1. Purpose

This factual report was prepared to assist planning for the proposed earthen constructed wetland in St. Charles

Township in Floyd County, Iowa. Our services were authorized by Mr. Nathan Anderson of WHKS.

A.2. Scope

To obtain data for analysis, our services included a total of 6 penetration test borings, drilled to depths of 16 to

41 feet below the surface. Our engineering scope consisted of providing a factual discussion of the soils and

materials encountered during our exploration.

A.3. Boring Locations and Elevation

The desired borings locations were indicated to Chosen Valley Testing on site plans provided by the client.

The Boring Location Sketch in the Appendix shows the approximate locations drilled. Elevations were

estimated using the Iowa DNR LiDAR software. These elevations should be considered approximate.




A.4. Geologic Background

A geotechnical report is based on subsurface data collected for the specific structure or problem. Available

geologic data from the region can help interpretation of the data and is briefly summarized in this section.

Area geologic maps indicate that the natural upper soils are primarily glacial deposits of sand, silt and clay

mixtures. Bedrock is expected to be within 100 feet from the surface and consist of dolomite and limestone of

the Cedar Valley Group

B. Subsurface Data

Methods: All of the borings were performed using penetration test procedures (Method of Test D1586 of the

American Society for Testing and Materials). This procedure allows for the extraction of intact soil specimen

from deep in the ground. With this method, a hollow-stem auger is drilled to the desired sampling depth. A 2-

inch OD sampling tube is then screwed onto the end of a sampling rod, inserted through the hole in the auger's

tip, and then driven into the soil with a 140-pound hammer dropped repeatedly from a height of 30 inches above

the sampling rod. The sampler is driven 18-inches into the soil, unless the material is too hard. The samples are

generally taken at 2½ to 5-foot intervals. The core of soil obtained is classified and logged by the driller and a

representative portion is then sealed in a jar and delivered to the soils engineer for review.

B.1. Stratification

At the surface, the southeast boring (Boring B-7) encountered peat, to a depth of about 5 ½ feet. The remaining

borings encountered topsoil at the surface, to depths of about 1 to 2 feet.

Clayey sand was encountered below the topsoil layer in the southwest boring (Boring B-6) to a depth of about

5 feet. In the northeast boring (Boring B-8) clean sand was encountered to depths of about 7 ½ feet.

Glacial till consisting of sandy lean clay was encountered below the clayey sand, clean sand, peat and topsoil

layers, where sands were not encountered. The borings terminated in the glacial clays at depths of about 16 to

41 feet below the surface.

The following simplified cross-section summarizes the boring data. For more detailed information, please refer

to the Log of Boring sheets in the Appendix.




1015

1020

1025

1030

1035

1040

1045

1050

1055

1060

1065

1070

1075

B-2 B-4 B-5 B-6 B-7 B-8

Approximate Depth (Feet)

Boring Number

Topsoil

Peat

Sand

Clayey Sand

Glacial Clay

Below Boring

B.2. Penetration Test Results

The number of blows needed for the hammer to advance the penetration test sampler is an indicator of soil

characteristics. The number of blows to advance the sampler 1 foot is called the penetration resistance or “N”-

value. The results tend to be more meaningful for natural mineral soils, than for fill soils. In fill soils, compaction

tests are more meaningful.

Penetration resistance values (N-values) of 3 to 77 Blows per Foot (BPF) were recorded in the glacial clays,

indicating they were very soft to hard. A penetration value of 5 BPF was recorded in the clayey sand, indicating

it was loose.

A key to the descriptors used to qualify the relative density of soil (such as soft, stiff, loose, and dense) can be

found on the Legend to Soil Description in the Appendix.

A pocket penetrometer was used to provide additional data on the compressive strength of the cohesive soils.

The glacial clays returned values of ¾ to greater than 4 ½ tons per square foot (tsf).




B.3. Groundwater Data

During the drilling operation, the drillers may note the presence of moisture on the sampling instrument, in the

cuttings, or within the borehole. These observations are recorded on the boring logs. The water level may vary

with weather; time of year and other factors and the presence or absence of water during the drilling is subject

to interpretation and is not always conclusive.

Water was observed in most of the borings during drilling, at depths of about 4 to 30 ½ feet below the surface.

These water levels correspond to elevations of about 1026 ½ to 1058 ½. Elevated moisture contents were also

recorded in most of the near surface glacial clays samples. This is likely due to water bearing seams of sand

becoming trapped within the less permeable clays. Groundwater levels at the site are expected to fluctuate

seasonally with nearby creeks and rivers, as well as with local weather patterns.

C. Level of Care

The services provided for this project have been conducted in a manner consistent with that level of care and

skill ordinarily exercised by members of the profession currently practicing in this area, under similar budget

and time constraints. This is our professional responsibility. No other warranty, expressed or implied, is made.




Appendix

Soil Boring Location Sketch

Log of Boring: 2, 4-8

Legend to Soil Description

N

Soil Boring Location Sketch Proposed Earthen Constructed Wetland

CREP Wetland Flo941603B

Section 3 – T95N – R16W

St. Charles Township, Floyd County, Iowa

CVT Proposal Number: 13244.18.IAM

C Chosen Valley Testing, Inc.

V T

Legend Boring Locations Benchmark

16.04759618.0

4759483.0

4759348.0

Elev. (ft)

4759390.0

4759418.0

16.0

1071.0

4759511.0

521961.0

Borehole

521964.0

521964.0

1061.0

1057.0 41.0

41.0

Eastng (m)

521931

522227

521931

522227CVT 13244.18.IAM (FLOYD COUNTY WETLANDS).GPJ FNC AB GWGN01.GDT 7/19/18

521964.0

1056.0

1060.0

522194.0

522171.0

16.0

Northing (m)

4759395

4759582

4759395

4759582

DISTANCES (m):

Beginning

Ending

VIEWING ANGLES (degrees):

Horizontal

Vertical

Elevation (ft)

Floyd County Wetland

Packard Ave, between 250th and 260th Sts

0

350

Easting (m)

Distance Along Baseline (m)

1066.0

1,015

1,020

1,070

1,020

1,075

1,015

1,0251,025

1,035

1,040

1,045

1,050

1,055

1,060

1,055

1,065

1,075

1,030

1,060

1,050

100 15050 200

1,045

0

1,040

300

1,070

1,035

1,065

350

16.0

1,030

250

Jul 18

Northing (m)

PROJECT # DATE PLATE

SUBSURFACE FENCE DIAGRAM

B-2

B-4

B-5

B-6

B-7

B-8

13244.18.IAM

0 50 100 150 200 250 300 350

Position

Left, Front

Right, Front

Left, Back

Right, Back

Depth (ft)

0.0

0.0

15

20

12

11

3

23

25

13

17

4

B-2

14

B-6

2

6

20

B-5

5

16

B-7

15

14

B-4

5

20

15

21

26

21

35

77

B-8

Slightly Organic SANDY LEAN CLAY(Topsoil)

1059.3

1052.8

1044.3

B-2 page 1 of 1

1.0

LEAN CLAY with SAND trace gravel, dark gray,wet, rather stiff.

(Glacial Till)

CVT STANDARD 13244.18.IAM (FLOYD COUNTY W

ETLANDS).GPJ LOG A GNNN06.GDT 7/19/18

3

11

1216.0

7.5

CLOL

PP = 0.75 tsf, MC = 19.0%

PP = 2.25 tsf

PP = 2.5 tsf, MC = 18.6%

End of boringBoring sealed upon completion

Tests and NotesDepthElev.

SANDY LEAN CLAY brown, wet, soft.(Glacial Till)

USCSSymbol

DATE: 6/27/2018

Description of Materials(ASTM D 2487/2488)

WL

PROJECT:

13244.18.IAM

BORING:

0.0

B-2

1060.3

L O G O F B O R I N GCHOSEN VALLEY TESTING

SCALE: 1" = 6'

BPF

13244.18.IAM

Design Phase Geotechnical Evaluations



Charles City, Iowa

See attached sketchLOCATION:

1.2Slightly Organic SANDY LEAN CLAY

(Topsoil)

PP = 1.0 tsf, MC = 23.0%

PP = 2.25 tsf

PP = 1.5 tsf



PP = 2.75 tsf

MC = 15.4%

7.5

41.0

1055.2

1048.9

1015.4

PP > 4.5 tsf

CLOL

PP = 3.5 tsf, MC = 15.4%

4

17

13

25

23

14

20

15

SANDY LEAN CLAY seams of sand, dark gray,very wet, rather soft.

(Glacial Till)

BPF

13244.18.IAM




Charles City, Iowa


LOCATION:

USCSSymbol

Tests and NotesDepth

SCALE: 1" = 6'

Water encountered at about15 feet during drilling.PP = 1.25 tsf, MC = 23.2%

WLElev.

DATE: 6/27/2018

B-4 page 1 of 1

LEAN CLAY with SAND trace gravel, dark gray,wet, stiff to very stiff.

(Glacial Till)

Very wet below 12.5'

Wet below 22.5'

Brown below 37.5'

See attached sketch

0.0

L O G O F B O R I N G

BORING:PROJECT:

1056.4

13244.18.IAM

B-4

CHOSEN VALLEY TESTING

1.0 Slightly Organic SANDY LEAN CLAY(Topsoil)

PP = 1.75 tsf, MC = 24.2%

PP = 1.5 tsf, MC = 24.2%

PP = 4.5 tsf



PP = 1.5 tsfWater encountered at about30.5 feet during drilling.

PP = 4.5 tsf

7.5

41.0

1056.3

1049.8

1016.3

PP > 4.5 tsf, MC = 12.7%

CLOL

PP = 2.75 tsf

5

20

15

21

26

21

35

77

SANDY LEAN CLAY brown, wet, rather soft.(Glacial Till)

BPF

13244.18.IAM




Charles City, Iowa


LOCATION:

USCSSymbol


SCALE: 1" = 6'

PP = 3.5 tsf

WLElev.

DATE: 6/27/2018

B-5 page 1 of 1

LEAN CLAY with SAND trace gravel, dark gray,wet, stiff to hard.

(Glacial Till)

Seams of sand around 30.5'

Brown below 37.5'


See attached sketch

0.0


BORING:PROJECT:

1057.3

13244.18.IAM

B-5


Slightly Organic LEAN CLAY(Topsoil)

1070.0

1066.2

1055.2

1.2

LEAN CLAY with SAND gray, wet, raterh soft tostiff.

(Glacial Till)




CLOL

5

16

16.0

5.0

SC

PP = 1.5 tsf

PP = 3.5 tsf, MC = 17.5%

PP = 3.5 tsf

Trace gravel below 7.5'Dark gray below 7.5'


B-6 page 1 of 1

CLAYEY SAND fine to medium grained, brown,moist, loose.

(Glacial Till)

USCSSymbol

DATE: 6/27/2018


WL

B-6

13244.18.IAM

0.0Elev.

LOCATION:

BORING:

BPF

See attached sketch

13244.18.IAM




Charles City, Iowa

PROJECT:

SCALE: 1" = 6'



1071.2

BORING:

1060.1

1049.6

PEAT(Swamp Deposit)

LEAN CLAY with SAND trace gravel, dark gray,wet, medium to very stiff.

(Glacial Till)


16.0



B-7 page 1 of 1

0.0

Seams of sand around 15'

2

6

No sample return

Water encountered at about7 feet during drilling.

PP = 1.5 tsf, MC = 22.0%

PP = 1.5 tsf

5.5

20

DATE: 6/27/2018

Depth

B-7

Tests and NotesElev.Description of Materials(ASTM D 2487/2488)

WL


13244.18.IAM

1065.6


SCALE: 1" = 6'

BPF

13244.18.IAM




Charles City, Iowa

See attached sketchLOCATION:

USCSSymbol

PROJECT:

Slightly Organic LEAN CLAY(Topsoil)

1059.0

1053.5

1045.0

2.0

LEAN CLAY with SAND trace gravel, dark gray,wet, very stiff.

(Glacial Till)



CLOL

15

1416.0

7.5

SP

Water encountered at about4 feet during drilling.

PP = 1.25 tsf, MC = 20.5%

PP = 3.5 tsf, MC = 16.6%



B-8 page 1 of 1

POORLY GRADED SAND trace gravel, seams oflean clay, fine to medium grained, brown, wet towater bearing.

(Alluvium)

USCSSymbol

DATE: 6/27/2018


WL

B-8

13244.18.IAM

0.0Elev.

LOCATION:

BORING:

BPF

See attached sketch

13244.18.IAM




Charles City, Iowa

PROJECT:

SCALE: 1" = 6'



1061.0

GROUPSYMBOL

SOIL GROUP NAMES & LEGEND

PRIMARILY ORGANIC MATTER, DARK IN COLOR, AND ORGANIC ODOR

BLOWS/FOOT* CONSISTENCY

SAMPLE TYPES

Job No. 13244.18.IAM

GRAVELS WITH FINES

>12% FINES

2.0 - 4.0OVER 4.0

TERM

TraceWith

Modifier

0.50 - 1.0

1.0 - 2.0

0 - 0.250.25 - 0.50

GW

GP

GM

GC

SW

SP

SM

SC

CL

ML

OL

CH

MH

OH

PT

CLEAN GRAVELS

<5% FINES

WATER LEVEL (WITH TIME OF)

MEASUREMENT

0 - 4

4 - 10

10 - 30

30 - 50

OVER 50

LIQUID LIMIT (%)

CH

0

10

20

30

40

50

60

70

80

PLASTICITY INDEX (%)

SIZE

< 12 in.3 in. - 12 in.

#4 sieve to 3 in.#200 sieve to #4 sievePassing #200 sieve

TERM

BoulderCobbleGravelSand

Silt or Clay

SAND & GRAVEL

CRITERIA FOR ASSIGNING SOIL GROUP NAMES

-

-

-

MC

OC

CN

DD

PP

RV

SA

P200

>50% OF COARSEFRACTION PASSESON NO 4. SIEVE

RELATIVE DENSITY

(RECORDED AS BLOWS / 0.5 FT)

CL

SILT & CLAY

NUMBER OF BLOWS OF 140 LB HAMMER FALLING 30 INCHES TO DRIVE A 2 INCH O.D.

(1-3/8 INCH I.D.) SPLIT-BARREL SAMPLER THE LAST 12 INCHES OF AN 18-INCH DRIVE

(ASTM-1586 STANDARD PENETRATION TEST).

*

BLOWS/FOOT*

WELL-GRADED GRAVEL

POORLY-GRADED GRAVEL

SILTY GRAVEL

CLAYEY GRAVEL

WELL-GRADED SAND

POORLY-GRADED SAND

SILTY SAND

CLAYEY SAND

LEAN CLAY

SILT

ORGANIC CLAY OR SILT

FAT CLAY

ELASTIC SILT

ORGANIC CLAY OR SILT

PENETRATION RESISTANCE

Hollow Stem

LEGEND TO SOIL

DESCRIPTIONS

FINES CLASSIFY AS ML OR CL

FINES CLASSIFY AS CL OR CH

PI>7 AND PLOTS>"A" LINE

PI>4 AND PLOTS<"A" LINE

LL (oven dried)/LL (not dried)<0.75

PI PLOTS >"A" LINE

PI PLOTS <"A" LINE

LL (oven dried)/LL (not dried)<0.75

COMPRESSIVE

STRENGTH (TSF)

Chosen Valley Testing

-

CLEAN SANDS

<5% FINES

SANDS AND FINES

>12% FINES

INORGANIC

MOISTURE CONTENT

ORGANIC CONTENT

CONSOLIDATION

DRY DENSITY

POCKET PENETROMETER

R-VALUE

SIEVE ANALYSIS

% PASSING #200 SIEVE

LIQUID LIMIT

PLASTISITY INDEX

SWELL TEST

Unconsolidated Undrained triaxial

LL

PI

SW

UU

PERCENT

< 55 - 12> 12

Relative Proportions of Fines

Standard Penetration Test

VERY SOFTSOFTRATHER SOFTMEDIUMRATHER STIFFSTIFFVERY STIFFHARD

UNIFIED SOIL CLASSIFICATION (ASTM D-2487/2488)

ML

MH

-

-

-

-

-

-

-

-

TEST SYMBOLS

PERCENT

< 1515 - 29> 30

ORGANIC

Relative Proportions of Sand and Gravel

0 - 12 - 34 - 56 - 89 - 1213 - 1617 - 30OVER 30

INORGANIC

TERM

TraceWith

Modifier

Grain Size Terminology

Cu>4 AND 1<Cc<3

Cu>4 AND 1>Cc>3

FINES CLASSIFY AS ML OR CL

FINES CLASSIFY AS CL OR CH

ORGANIC

VERY LOOSE

LOOSE

MEDIUM DENSE

DENSE

VERY DENSE

GRAVELS

0 10 20 30 40 50 60 70 80 90 100 110 120

MATERIALTYPES

Cu>6 AND 1<Cc<3

Cu>6 AND 1>Cc>3

CVT 13244.18.IAM (FLOYD COUNTY W

ETLANDS).GPJ 7/19/18

PEAT

SANDS

SILTS AND CLAYS

LIQUID LIMIT>50

SILTS AND CLAYS

LIQUID LIMIT<50

>50% OF COARSEFRACTION RETAINED

ON NO 4. SIEVE

HIGHLY ORGANIC SOILS

COARSE-G

RAINED SOILS

>50% RETAINED ON

NO. 200 SIEVE

FINE-G

RAINED SOILS

>50% PASSES

NO. 200 SIEVE

PLASTICITY CHART

"A" LINE

CL-ML

Documents

Proposed Earthen Constructed Wetland CREP Wetland