ADDENDUM

Addendum No. 2

Owner: West Shore Community College

Project: Contract B - 50,000 Gallon Elevated Tank Date: June 4, 2019

Owner’s Contract No.: N/A Engineer’s Project No.: 836850

ENGINEER: Fleis & VandenBrink Engineering, Inc.

NOTICE TO ALL PROSPECTIVE BIDDERS

BIDS DUE: ***2:00 p.m. Thursday, June 6, 2019*** (NO CHANGE)

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This Addendum is a part of the Contract Documents and modifies the previously issued Bidding Documents. Acknowledge receipt of this Addendum in the space provided on the Bid Form. Failure to do so may result in rejection of the Bid.

SPECIFICATION CHANGES ITEM NO. 1:

The Geotechnical report in Appendix A has been amended to provide additional recommendations and a greater range of augercast pile lengths and capacities for the design of the water tank.

Add attached addendum letter to geotechnical report in Appendix A.

ATTACHMENTS:

• Addendum Letter from Soils and Structures

ADDENDUM #2

ADDENDUM LETTER FOR THE

WEST SHORE COMMUNITY COLLEGE WATER TANK

SCOTTVILLE

MASON COUNTY MICHIGAN

JUNE 3, 2019

Fleis & Vandenbrink

2960 Lucerne Drive SE

Suite 100

Grand Rapids, Michigan 49546

Project No. 2018.1981

ADDENDUM #2

June 3, 2019

Fleis & Vandenbrink

2960 Lucerne Drive SE

Suite 100

Grand Rapids, Michigan 49546

Attention: Mr. Michael Mattzela, P.E.

Regarding: West Shore Community College – Water Tank Scottville, Mason County, Michigan

Project No. 2018.1981

Dear Mr. Mattzela:

This letter is an addendum to the geotechnical report for the water tank at West Shore

Community College in Scottville, Mason County, Michigan which was delivered on March 8,

2019.

The purpose of the letter is to provide additional recommendations and a greater range of

augercast pile lengths and capacities for the design of the water tank.

We appreciate the opportunity to provide engineering services to Fleis & Vandenbrink. If you

have any questions regarding this letter, please contact our office.

Sincerely,

Soils & Structures, Inc. Reviewed by:

Michael J. Partenio, E.I.T. David W. Hohmeyer, P.E.

MJP/mp

ADDENDUM #2

Shallow Foundation Recommendations

The in-situ sand is loose and not suitable for support of a shallow foundation in its existing state.

Due to the high water table, compaction of the sand in place will not be beneficial. If shallow

foundations are desired, the in-situ sand should be excavated to its full depth and placed back in

the excavation with compaction.

Sheet piling is recommended to support the soil during excavation. The sheet pile should be

embedded a minimum of 3.0 feet into the clay layer. The sheet pile should be designed by an

engineer. Dewatering will be required for the excavation. The in-situ sand should be removed to

its full depth. A layer of filter fabric or geogrid should be placed over the clay at the bottom of the

excavation. A 6.0 to 8.0 inch layer of porous stone should be placed above the filter fabric or

geogrid.

The lateral earth pressure against foundations and the sheet pile walls should be designed using

a soil density of 130 pounds per cubic foot, a coefficient of active earth pressure of 0.35 for level

sand backfill, and a coefficient of at-rest earth pressure of 0.50. The effects of any surcharge or

sloping backfill should also be included in the design. The passive resistance of the existing sand

should be calculated using an earth pressure coefficient of 3.0.

Fill placed below the foundations should be sand meeting MDOT Class II requirements. Fill should

be compacted to 96.0 percent of its maximum density. The maximum density should be

determined in accordance with the ASTM D 1557 standard. A maximum thickness per layer of

6.0 inches is recommended. Compaction tests are recommended to confirm that the fill is

compacted to the required density.

Foundations may be designed using an allowable soil bearing value of 2,000 pounds per square

foot provided the recommendations in the previous paragraphs are followed. The allowable

bearing value may be increased 25.0 percent when considering transient loads such as

earthquakes and wind.

Pile Foundation Recommendations

Augercast piles are a recommended option for support of the tank. Table 1 lists the estimated

pile lengths for a range of ultimate pile capacities for 12.0, 14.0, 16.0, and 18.0 inch diameter

augercast piles.

ADDENDUM #2

Table 1: Estimated Pile Lengths for Augercast Piles

Ultimate Pile

Capacity

(kips)

Estimated Pile Length (feet) 12”

Diameter

14”

Diameter

16”

Diameter

18”

Diameter 80 36 32 29 26

100 41 37 33 30

120 47 42 37 34

160 59 51 46 42

200 70 61 55 49

210 73 64 57 51

220 76 66 59 53

*NOTE: Based on assumed top of pile elevation of 684.0 feet.

The pile lengths are based on a cutoff elevation of 684.0 feet. If the cutoff elevation is different,

the pile lengths must be adjusted accordingly.

Augercast piles should be reinforced with one number eight bar the full length of the pile. The

grout should have a twenty eight day strength of 4,000 pounds per square inch. The piles should

also be installed in accordance with generally accepted practices of augercast pile installation.

The recommended minimum center to center pile spacing for augercast piles is 3.0 times the

pile diameter. If piles are constructed in a single ring formation below the tank, an efficiency

factor of 0.875 is recommended for each pile. An efficiency factor of 1.0 is recommended for

piles spaced more than 5.0 times the pile diameter from the nearest pile.

A minimum safety factor of 2.0 is recommended for axial capacity. A minimum safety factor of

3.0 is recommended for uplift resistance.

Each augercast pile will generate 1.5 to 4.5 cubic yards of excess soil or spoil that will have to

be removed from the site. The spoil should be removed from the top of each pile as it is

generated.

The recommended minimum cover over the pile caps is 24.0 inches.

ADDENDUM #2

Pile caps should not be constructed on frozen soil. Pile caps should be protected from freezing

with insulated blankets. Pile caps exposed to extended periods of freezing temperatures will

heave which may damage the foundation and any overlying structures.

Quality Control Testing

Full time inspection of the pile installation is recommended. For each augercast pile, the following

information should be recorded: drilling time, grouting time, grout volume, grout ratio, offsets,

and obstructions.

The strength of the concrete and augercast grout should be verified by concrete test cylinders.

One set of four cylinders is recommended for each half day of production. Pile Integrity Testing

(PIT) is recommended to verify the augercast pile integrity. The PIT is a low strain, non-destructive

method for testing piles and should be performed in accordance with ASTM D 5882 standards.

One pile load test is recommended. The pile load test should be performed in accordance with

the ASTM D 1143 standards using the “Quick Load Method”. The test pile should be loaded to

250.0 percent of the design capacity. A geotechnical engineer should observe the test and

provide documentation and confirmation that the pile possesses the required capacity.

Compaction tests (ASTM D 6938) are recommended to confirm that fill in the construction area

is compacted to the specified density. While fill is being placed, compaction tests should be

performed at the rate of one test per 400 cubic yards of fill and throughout the depth of the fill

with a minimum of five tests at each 1.0 foot elevation interval. Full time inspection is

recommended while the sand is compacted in the construction area. The maximum density

should be determined in accordance with ASTM D 1557 or ASTM D 4253 procedures.

A smooth 0.5 to 0.75 inch diameter rod should be used in conjunction with compaction tests to

probe for loose areas.

A dynamic cone should not be substituted for compaction tests for evaluating fill.

Testing should be performed by technicians supervised by a registered geotechnical engineer.

ADDENDUM #2

General Conditions & Reliance

This letter was prepared in accordance with generally accepted practices of the geotechnical

engineering profession. The letter may be relied upon by Fleis & Vandenbrink for the design,

construction, permitting and financing associated with the construction of the water tank project

at West Shore Community College in Scottville, Mason County, Michigan. Soils & Structures

should be consulted if a significant change in the scope of the project is made.

The recommendations contained in this letter are based on an interpretation of the test borings

and laboratory tests contained in the previous report dated March 8, 2019. The use of this

letter by third parties not associated with this project or for other sites has not been agreed

upon by Soils & Structures. Soils & Structures does not recommend or consent to third party

use or reliance of the letter unless allowed to review the proposed use of these materials. Unless

obtained in writing, consent to third party use should not be assumed. Third parties using the

letter do so at their own risk and are offered no guarantee or promise of indemnity.

ADDENDUM #2