test pit observation report - albertville · test pit observation report albertville business park...

Test Pit Observation Report

Albertville Business Park 67th Street to 70th Street NE Albertville, Minnesota

Prepared for

Fehn Companies

Professional Certification:

I hereby certify that this plan, specification, or 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 Minnesflta• 111,,,,

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April 28, 2011 ,,,,�10F Milli',,,,,, ''"'"''

Project BL-11-01724

Braun lntertec Corporation

BRAUN

INTERTEC

AUAR Update, Albertville Business Park Appendix D

1B RA IU N

INTERTEC

April 28, 2011

Mr. Gary Fehn

Fehn Companies

5050 Barthel Drive

PO Box 256

Albertville, MN 55301

Re: Test Pit Observation Report

Albertville Business Park

67th Street and 70th Street NE

Albertville, Minnesota

Dear Mr. Fehn:

Braun lntertec Corporation Phone 952.995.2000

11001 Hampshire Avenue S Fox· 952.995.2020

Minneapolis, MN 55438 Web: brounintertec.com

Project BL-11-01724

We have recently completed observations of test pit excavations at the above referenced property

followed by laboratory soil tests. The purpose of the test pits and laboratory tests was to assist in

evaluating the subsurface soil and groundwater conditions with respect to design and support of the

proposed commercial development being considered for this property.

Scope

On April 18, 2011, we completed observations of a total of 29 test pits at the approximate locations as

shown on the test pit location sketch prepared by RLK Incorporated (RLK), and attached to this letter.

Twenty eight test pits had originally been staked in the field by RLK. Test pit 29 was added in the field by

the land owner, Mr. Darkenwald. Test pit 29 was to explore soil conditions in the stockpile of soil located

in the northeast area of the site (see sketch).

From the test pits we obtained several bag samples of soils to return to the laboratory for tests to

determine the organic content, or the moisture content, of the soil samples. The lab test results will be

used to aid in estimating the effort needed to prepare this site for construction.

Results

The attached table gives details of ground elevations, soil types and estimated depths of soil corrections.

In a brief overview, the soils encountered by the test pits generally consisted of about 1/2 foot to 3 and

1/2 feet of topsoil underlain by native lean clays and some silty sands to the test pit termination depths.

At one location about 8 feet of clayey fill was found below the topsoil. At the stockpile location the fill

was about 10 feet thick and underlain with buried topsoil and then native clays.

At many locations the near surface clayey soils were excessively wet and often in a soft condition. Below

the topsoil, fill, and soft, wet clay soils, the test pits generally encountered a mixture of naturally

deposited glacial till soils, including sandy lean clay, silty sand and some traces or thin layers of sand.

Very minor amounts of gravel were also observed in some of the test pits.

BRAUN

-------- --- - - - ---------0 Providing engineering and environmental soludch-J.1'i[[gf 56(


Fehn Companies

Project BL-11-01724

April 28, 2011

A tabulation of the soils encountered at the individual test pits is attached to this report. This tabulation

provides more details of soil conditions at the test pit locations. Note that soil consistencies shown on

the logs were implied based on field observations.

Groundwater was only observed in a few test pits seeping in from thin layers of more granular soils.

Since water was not observed in most of the test pits, it is likely that the water observed was perched

within these layers of sand.

Recommendations

As project designs progress, we recommend that deep standard penetration soil borings be performed in

strategic building, street and retention pond areas. The borings will explore soil conditions at depth and

gather soil strength information to be used in building foundation design and determination of allowable

soil bearing pressures for footings. With that information, additional site grading and construction

recommendations can also be provided.

Based on the test results at this time, we provide the following preliminary comments. We recommend

removing the topsoil, fill and possible fill from beneath any future building pads and streets. Also, at

several locations additional subcuts will be needed to remove near surface, soft, wet clayey soils which

are in an unstable condition. Anticipated excavation depths for topsoil removed and/or soil corrections

at each of the test pits are shown in Table 1.

The excavations to remove unsuitable soils should also be extended laterally at least 1 foot for each foot

of fill needed below bottom of perimeter footings (1:1 oversizing).

In some areas of this site, existing structures and underground utilities exist. All building debris and

buried lines should be removed beneath future building pad and oversize areas. This process will then

also remove the fill soils used to backfill underground lines and allow this fill to be replaced as

engineered fill.

Due to the variability in soil conditions and depths of old fill soils, all building pad excavations will need to

be observed by a qualified geotechnical engineer or representative. The observations are to document

the complete removal of all unsuitable fill and/or natural soils prior to placement of new, engineered fill

soils or building footings and slabs.

The test pit excavations were not recompacted when they were refilled. Therefore all of these test pit

excavation areas will need to be re-excavated and refilled with properly compacted soils.

In the areas where soil correction work is needed, we recommend that any engineered fill consist of

mineral soil, free of debris and organic material. Any cobbles or boulders should also be removed from

any engineered fill soil used.

BRAUN

INTERTEC


Fehn Companies

Project BL-11-01724

April 28, 2011

Page4

Engineered fill placed within the building pads should be placed in lifts of 8 to 12 inches, depending on

the fill soil used and the size of the compactor used. The fill should be compacted to a minimum of

95 percent of the standard Proctor dry density (ASTM D698), however, based on the proposed

construction, higher soil compaction levels may be needed. If fill depths exceed 10 feet, the fill should be

compacted to a minimum of 98 percent. For fill soils placed below streets, the fill should be compacted

to a minimum of 95 percent, except in the upper 3 feet of subgrade, where the soil should be compacted

to a minimum of 100 percent.

The fill soils used as engineered fill should be placed at a moisture content of no less than 1 percentage

point below and no more than 3 percentage points above the soils optimum moisture content.

Remarks

These comments are based on shallow test pits only and soil conditions may change below the test pit

elevations. Deeper soil borings would reduce your risks of unknown soil conditions at depth. Please

contact us if you wish to perform soil borings or if additional construction recommendations are needed.

In performing its services, Braun lntertec used that degree of care and skill ordinarily exercised under

similar circumstances by reputable members of its profession currently practicing in the same locality. No

warranty, express or implied, is made.

If you have any questions about this report, please contact Henry Vloo at 952.995.2238 or Gregg Jandro

at 952.995.2270.

Sincerely,

BRAUN INTERTEC CORPORATION

�� fer

Henry Vloo, PE

Associate -Senior Engineer

Attachments:

Test Pit Soils Tabulation

Test Pit Location Sketch

Test Pit Report

BRAUN

INTERTEC


Table 1. Albertville Test Pit Soils Tabulation

SOILS Existing Ground

Test Pit Elevation Depth Description

0-3 1/2' Topsoil, Sandy lean clay, black, wet, soft

1 957.9 3 1/2-5' Sandy lean clay, dark brown and dark gray, wet, soft

5-9'+ Sandy lean clay, with trace of gravel, brown mottled with gray, wet, medium

0-1' Topsoil, Sandy lean clay, brown, trace of organics, soft, wet

2 964.2 1-2 1/2' Lean clay, brown and gray, wet, medium

2 1/2-4' Sandy lean clay, trace of gravel, brown mottled with gray, wet, medium

3 960.3 0-1' Topsoil, lean clay, brown, moist, soft

1-4+' Sandy lean clay, brown mottled with gray, wet medium

0-1/2' Topsoil, lean clay, brown, trace of organics, moist, soft

4 969.1 1/2-3' Sandy lean clay, with a trace of gravel, brown mottled with gray, wet, soft

3-7+' Sandy lean clay with a trace of gravel, brown mottled with gray, moist, medium

5 963.2 0-1' Topsoil, lean clay with a trace of organics, brown, moist, soft

1-4+' Sandy lean clay, with a trace of gravel, brown mottled with gray, wet, medium

6 962.6 0-1' Topsoil, lean clay, brown, moist, soft

1-4+' Sandy lean clay, brown mottled with gray, wet, medium

7 961.3 0-1' Topsoil, lean clay, slightly organic, brown, wet, soft

1-3' Sandy lean clay, brown mottled with gray, wet, soft


0-1' Topsoil, lean clay with a trace of organics, brown, moist, soft

8 963.7 1-3' Lean clay, brown and gray, wet, medium

3-5+' Sandy lean clay, with a trace of gravel, brown mottled with gray, wet, medium

0-8" Topsoil, lean clay with a trace of organics, brown, wet, soft

9 961.4 8"-1' Sandy lean clay, brown mottled with gray, wet, soft

1'-3+' Sandy lean clay, brown mottled with gray, wet, medium

0-3' Topsoil, organic lean clay, black, wet, very soft

3-6' Lean clay, brown and gray mottled, wet, soft

10 957.4 6-9' Sandy lean clay, brown mottled with gray, wet, soft


Laboratory Test-

Organic Content%

6.3

2.9

2.6

3.9

Laboratory Estimated Test Depth of Soil

Moisture Correction Content% (ft)

40.6

32.7 5

24.2

1

19.3

21.4 1

3

19.5

20.0 1

24.4

1

3

1/2

1

25.8

26.9

27.3 9

BRAUN

INTERTEC



Existing SOILS

Test Pit Ground Elevation Depth Description

0-1/2' Topsoil, lean clay, with a trace of organics, brown, wet, soft 11 962.7 1/2-11/2' Lean clay, brown and gray, moist, medium

11/2·5+' Sandy lean clay, with a trace of gravel, brown mottled with gray, wet, medium

0-1' Topsoil, silty sand, brown, moist, loose 12 96 7.8

1-5+' Sandy lean clay, brown mottled with red, wet to moist, medium

0-1' Topsoil, lean clay with a trace of organics, moist, soft 13 962.0 1·2' Lean clay, brown and gray mottled, wet, medium

2-4'+ Sandy lean clay, brown mottled with gray, wet, stiff

0-11/2' Topsoil, lean clay, black, wet, soft.

14 956.5 11/2-41/2' Lean clay, brown and gray mottled, wet, soft 4 1/2-6 1/2+' Sandy lean clay, brown and gray mottled, wet, medium

0-11/2' Topsoil, lean clay with a trace of organics, brown, wet, soft

15 957.9 11/2·3' Lean clay, brown and gray mottled, wet, soft 3-7' Sandy lean clay, brown and gray mottled, wet, soft 7-9'+ Sandy lean clay, brown and gray mottled, wet, medium

0·11/2' Topsoil, lean clay, with a trace of organics, brown, wet, soft 16 959. 5 11/2·3 1/2' Lean clay, brown and gray, wet, medium

3 1/2·8'+ Sandy lean clay with a trace of gravel, brown and gray mottled, wet, medium

0-2' Topsoil, lean clay with a trace of organics, brown, wet, soft 17 960.0 2-3' lean clay, brown and gray, wet, medium

3- 6'+ Sandy lean clay, with a trace of gravel, brown and gray mottled, wet, medium

0-3' Topsoil, organic lean clay, black, wet, soft

18 956.0 3-6' Sandy lean clay, brown and gray mottled, wet, soft 6-7+' Sandy lean clay, brown and gray mottled, wet , medium

0-11/2' Topsoil, organic lean clay, black, wet, soft

19 957.2 11/2' .3 1/2' Lean clay, brown and gray mottled, wet, soft

3 1/2·6 1/2' Sandy lean clay, brown and gray mottled, wet, soft 6 1/2·7+' Sandy lean clay, brown and gray mottled, wet, medium

Laboratory Test·

Organic Content%

2 .7

2.8

4. 8

1. 8

3 .0

4. 5

Laboratory Estimated Test· Depth of Soil

Moisture Correction Content% (ft)

1/2

21.0

19.1 1

19.4

1

27.8

41/2

7

28. 3

17. 8 11/2

22.S

31.4

30 . 9 3

20 .2

30.7 6

22.7

2 9. 361/2

BRAUN

INTFRTF("



SOILS Existing

Ground

Test Pit Elevation Depth Description

20 954.8 0-2' Topsoil, lean clay, dark brown, wet, soft

2-5+' Sandy lean clay, brown and gray mottled, wet, medium

0-1/2' Topsoil, lean clay, with a trace of organics, brown, wet, medium

1/2-3' Sandy lean clay, with a trace of gravel, brown, moist, medium (Fill)

21 960.3 3-4' Silty sand with gravel, brown, moist, medium dense (Fill)

4-8' Sandy lean clay, brown and gray, moist, medium (Fill)

8-10' Sandy lean clay, with a trace of gravel, brown mottled with gray, moist to wet, medium

22 957.7 0-1' Topsoil, lean clay, dark brown, moist, soft

1-4+' Sandy lean clay, brown and gray mottled, wet to moist, soft to medium @ 11/2'

0-1' Topsoil, lean clay, dark brown, wet, soft

23 956.7 1-4' Sandy lean clay, brown and gray mottled, wet, soft

4-5+' Sandy lean clay, brown and gray mottled, wet, medium

0-11/2' Topsoil, organic lean clay, black, wet, soft

24 954.7 11/2-4 Silty sand with sandy lean clay, gray to brown, waterbearing sand seams, medium

1/2+' dense

0- 2' Topsoil, lean clay, with organics, black, wet, soft

25 954.2 2-41/2+' Silty sand with sandy lean clay, brown mottled with gray, moist to wet, loose to

2 1/2', then medium

0-2' Topsoil, lean clay, black to dark gray, moist, soft

26 956.6 2-9+' Sandy lean clay, brown mottled with gray, moist, medium, lenses of waterbearing

silty sand

27 957.5 0-1' Topsoil, lean clay, dark brown, wet, soft

1-6'+ Sandy lean clay, brown mottled with gray, wet, medium

0-2' Topsoil, lean clay, with organics, black, wet, soft

28 953.6 2-7' Sandy lean clay, brown and gray mottled, wet, soft

7-9'+ Sandy lean clay, brown and gray mottled, wet, medium

Estimated 0-10' Sandy lean clay, brown mottled with gray, moist (Fill)

29 10-11' Buried Topsoil, lean clay, black and brown, moist

(Stockpile) 970± 11 -1 2') Sandy lean clay, brown and gray mottled, wet, medium

*This gradation classified soil as silty sand.

Laboratory

Test-

Organic

Content%

3.0

3.8

2 .5

6.5

Laboratory Estimated

Test Depth of Soil

Moisture Correction

Content% (ft)

2

20.9 1/2' Topsoil

18.2 Fill to 8'

26.4 11/2'

27.3

28.2 4

11/2

29.3

(34%-200)* 21/2

20.7 2'

21.0 1'

30.7

32.0 7'

26.8

20.4 Fill to 10'

Topsoils 10

to 11 '

BRAUN

INTFRTFC-


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April 14, 2011


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