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j:\clerical\wylie\2015-155 nortex gsr\specs\re-bid\addendum\add-3 (re-bid).docx - 1 - Addendum No. 3

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I Acknowledge the receipt of Addendum No. 3

City of Wylie, Texas

Project Name: Nortex 1.0-MG Ground Storage Reservoir (Bid #W2018-33-B)

By Facsimile Transmission on this date: January 15, 2018

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j:\clerical\wylie\2015-155 nortex gsr\specs\re-bid\addendum\add-3 (re-bid).docx - 2 - Addendum No. 3

CITY OF WYLIE, TEXAS

NORTEX 1.0-MG GROUND STORAGE RESERVOIR

Project No. W2018-33-B

ADDENDUM NO. 3

Plans and specifications for the Nortex 1.0-MG Ground Storage Reservoir (Project No. W2018-33-B),

for the City of Wylie, Texas, on which bids are to be received until 3:00 p.m., Friday, January 19,

2018, are hereby modified as follows:

1. CLARIFICATION QUESTIONS & ANSWERS:

The following questions and answers do not require any revision to the plans, specifications or

contract documents and are provided for clarification and information purposes:

A. (Q) There is no bid item for Mobilization, Bonds & Insurance. Where would you like for

us to include the costs?

(A) It is not unusual for there to be no separate bid item for these costs. The contractor is

solely responsible for including these subsidiary costs to the bid item or items as they

deem appropriate.

B. (Q) Can you clarify the excavation of the existing tank based on the bid items?

(A) Bid Item #4 includes the excavation of the first 4 feet of soil below the existing steel

tank and ring beam, whether contaminated (oiled sand) or not. There is approximately

800 cubic yards of material included in the excavation for this bid item. Bid Item #5 is

a contingency in case the contaminated soil extends beyond 4 feet below the existing

tank. The quantity for Bid Item #21 has been revised to account for the increased total

excavation quantity minus the amount for tank removal in Bid Item #4. A revised

geotechnical report issued with this addendum clarifies design parameters for the slab

and footing and increased the overall depth of excavation by 1 foot.

2. BID SCHEDULE

Please delete the Bid Schedule attached to the original specifications and contract documents and

replace it with the attached revised Bid Schedule (Pages BS-2A through BS-8A). The following

summarizes the revisions made to the attached Bid Schedule:

• Refer to Bid Item 21 – “Unclassified Excavation for GSR Minus Existing Tank Removal

(Plan Quantity)”:

The total overall quantity of excavation for the ground storage reservoir, including existing

tank removal is approximately 4,210 cubic yards. The approximate quantity of excavation

for the first 4 feet below the existing tank is 800 cubic yards. The revised plan quantity is

therefore, 3,410 cubic yards.

• Refer to Bid Item 22 – “Furnish & Install Flexible Base for Foundation and 3-foot Perimeter

Backfill for GSR (Plan Quantity)”:

The revised geotechnical report increased the thickness of the foundation by 1-foot

increasing the quantity of this item by 310 cubic yards.

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended

Amount

1 1 L.S.

complete in place, the sum of

Dollars

and

Cents per

2 146 S.Y.


Dollars

and

Cents per

3 400 L.F.


Dollars

and

Cents per

4 1 L.S.


Dollars

and

Cents per

5 4 V.F.


Dollars

and

Cents per

Project No. 2018-33-B

Remove & Properly Dispose of Additional

Contaminated Soil > 4-Ft. Below Existing Tank

Foundation

Vertical Foot

Linear Foot

Lump Sum

Lump Sum

Square Yard

Description and Price in Words

BID SCHEDULE

CITY OF WYLIE, TEXAS

Nortex 1.0-MG Ground Storage Reservoir

AWWA D110, Type III

Furnish & Install New Electrical Conduits &

Wiring from Existing Electrical Control

Building to Existing Pump Station Building

Construct Temporary Access Drive and

Temporary Gate to Existing Pump Station

Remove & Properly Dispose of Existing 917,500

Gallon Bolted Steel Tank, Ring Beam and Soil

(Net Cost)

Remove and Replace Existing 8-foot Security

Fence (Wood or Chain Link)

J:\CLERICAL\Wylie\2015-155 Nortex GSR\Specs\Re-Bid\Tech-Spec\06-P&BS-2.xlsx

BS-2A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended

Amount Description and Price in Words

6 317 S.Y.


Dollars

and

Cents per

7 418 S.Y.


Dollars

and

Cents per

8 26 L.F.


Dollars

and

Cents per

9 30 L.F.


Dollars

and

Cents per

10 104 L.F.


Dollars

and

Cents per

11 2 Ea.


Dollars

and

Cents per

Linear Foot

Each

Linear Foot

Linear Foot

Remove & Dispose of Existing 14" Discharge

Pipe

Remove & Dispose of Existing 24" Discharge

Pipe

Remove & Dispose of 14" Gate Valves

Remove & Dispose of Existing 14" Supply Pipe

Square Yard

Square Yard

Remove Existing 12' Wide, 6-inch Thick

Reinforced Concrete Access Drive on

Compacted Subgrade

Construct 12' Wide, 6-inch Thick Reinforced

Concrete Access Drive on Compacted Subgrade


BS-3A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended


12 1 Ea.


Dollars

and

Cents per

13 30 L.F.


Dollars

and

Cents per

14 1 L.S.


Dollars

and

Cents per

15 1 L.S.


Dollars

and

Cents per

16 50 L.F.


Dollars

and

Cents per

17 1 Ea.


Dollars

and

Cents per Each

Remove & Dispose of 24" Butterfly Valves

Lump Sum

Each

Connect to Existing 14" Supply Piping

Linear Foot

Construct 14" Yard Supply Pipe Including

Bends & Fittings (Outside GSR Piping)

Connect to Existing 24" Discharge Piping

Lump Sum

Construct 24" Yard Discharge Pipe including

Bends & Fittings (Outside GSR Piping)

Furnish & Install 24" Butterfly Valve with

Extended Operator (Discharge Side)

Linear Foot


BS-4A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended


18 1 Ea.


Dollars

and

Cents per

19 63 L.F.


Dollars

and

Cents per

20 1 Ea.


Dollars

and

Cents per

21 3,410 C.Y.


Dollars

and

Cents per

22 1,910 C.Y.


Dollars

and

Cents per

23 1 L.S.


Dollars

and

Cents per

Cubic Yard

Lump Sum

Furnish & Install 6" PVC Pipe Underdrain,

Manhole and Duplex Sump Pumps

Furnish & Install 8" Gate Valve with Extended

Operator (Drain Line)

Unclassified Excavation for GSR Minus

Existing Tank Removal (Plan Quantity)

Each

Linear Foot

Construct 8" Yard Drain Line (Outside GSR

Piping)

Cubic Yard

Furnish & Install Flexible Base for Foundation

and 3-Foot Perimeter Backfill for GSR (Plan

Quantity)

Furnish & Install 14" Butterfly Valve with

Extended Operator (Supply Side)

Each


BS-5A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended


24 1 L.S.


Dollars

and

Cents per

25 1 L.S.


Dollars

and

Cents per

26 2 Ea.


Dollars

and

Cents per

27 1 L.S.


Dollars

and

Cents per

28 1 L.S.


Dollars

and

Cents per

29 1 L.S.


Dollars

and

Cents per

Lump Sum

Lump Sum

Each

For Preparing and Submitting an Excavation

Safety Plan that is in conformance to latest

OSHA Standards

Furnishing and Installing a Complete Excavation

Safety and Support System in full accordance

with latest OSHA Standards

Lump Sum

Site Work/Grading Including Overflow Flume

Lump Sum

Furnish & Install SolarBee Model SB500PWc

v20 Tank Mixers

For Constructing a 1,000,000 Gallon, AWWA

D110, Type III, Prestressed Concrete Ground

Storage Reservoir, Internal Piping, Backfill and

all related appurtenances

Furnish & Install All Electrical & SCADA for

entire GSR Project

Lump Sum


BS-6A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended


30 1 L.S.


Dollars

and

Cents per

31 1 L.S.


Dollars

and

Cents per

32 146 S.Y.


Dollars

and

Cents per

33 225 L.F.


Dollars

and

Cents per

34 40 L.F.


Dollars

and

Cents per

35 1 L.S.


Dollars

and

Cents per

Linear Foot

Lump Sum

Lump Sum

Restore Healthy Stand of Grass for All

Disturbed Areas

Remove Temporary Access Drive to Pump

Station and Restore Fence After GSR

Construction is Completed

Square Yard

Remove and Replace Existing 6-Foot Wood

Privacy Fence

Design & Implement Storm Water Pollution

Prevention Plan

Remove and Replace Existing 6-Foot Chain

Link Fence

Linear Foot

Construct Temporary Drive for Access to

Construction Easements

Lump Sum


BS-7A

Addendum No. 3

Item

No.

Estimated

Quantity Unit

Price in

Figures

Extended


36 1 L.S.


Dollars

and

Cents per

37 1 L.S.


Dollars

and

Cents per

38 1 L.S. 45,000.00$ 45,000.00$


Dollars

and

Cents per

TOTAL AMOUNT BID (Items 1 Through 38)

Bid Allowance

No

Lump Sum

Owner's Contingencies Allowance

Forty Five Thousand

Restore Irrigation Sysytem and Landscaping for

Temporary Access Easement

Lump Sum

Remove Temporary Drive for Access to

Construction Easements

Lump Sum


BS-8A

Addendum No. 3

The seal appearing on this

document was authorized by

James F. Phipps, P.E. 84778

on August 15, 2016.

geotechnical and construction materials consultants

August 15, 2016 Report No. 15841G REVISED

Birkhoff, Hendricks & Carter, LLP 11910 Greenville Avenue, Suite 600 Dallas, Texas 775243 ATTN: Mr. Joe R. Carter, P.E., C.F.M. Phone: 214-361-7900 Email: [email protected]

RE: Geotechnical Investigation

Nortex Ground Storage Reservoir Towngate Drive Wylie, Texas

Gentlemen:

Presented herein is the report of a geotechnical investigation conducted by Henley-Johnston &

Associates, Inc. for the above referenced project.

We appreciate the opportunity to provide this report to you. If we can be of further service or if

you desire any additional information, please do not hesitate to call.

Signed,

HENLEY-JOHNSTON & Associates, Inc.

James F. Phipps, P.E.

Vice President

Firm Registration No.: F-1238

Copies submitted (1) Birkhoff, Hendricks & Carter, LLP – Mr. Joe R. Carter, P.E., C.F.M.

INDEX

INVESTIGATION AND ANALYSIS 1

Introduction 1

Field and Laboratory Investigation 1

Surface and Subsurface Conditions 2

Tank Pad Preparation 4

Excavations 5

Foundation Recommendations 6

Construction Considerations 6

Paving Recommendations 6

Earthwork Recommendations 8

Construction Testing and Observations 9

PLATES

Report No. 15841G REVISED August 15, 2016

- 1 -

INVESTIGATION AND ANALYSIS

Introduction

This report presents the results of a subsurface investigation performed for a proposed 1.0 million

gallon, concrete ground storage tank (GST) at the Nortex station located off Towngate Drive in

Wylie, Texas. At the time of this investigation, it was understood the proposed ground storage

tank would measure 74.56 feet in diameter, with a side water depth of 30.88 feet. The anticipated

contact pressure for this tank was estimated to be less than 2.1 ksf below the tank floor, and less

than 4 ksf beneath the tank perimeter. The finished floor elevation of the tank is anticipated to be

at least 1 foot above finished grade. Differential movements related to soil heave are to be

limited to 1 inch.

The purpose of this investigation was to identify and evaluated the subsurface conditions in the

area of the proposed tank. It was anticipated that a shallow foundation as described in ACI

372R-03 as consisting of a membrane floor slab with a monolithic perimeter wall footing would be

used for this project. Additionally, potential vertical movements due to soil heave are to be limited

to 1-inch. Per ACI, maximum differential settlement is to be limited to 0.7-inches or less from tank

center to tank edge for a 6-inch thick slab, and 0.35-inches for a 12-inch thick floor. Maximum tilt

is to be limited to 2.8-inches. Total uniform settlement is not to exceed 6 inches.

This report is specific to this project. Persons using the recommendations and information herein

for projects and/or designs not covered by this report do so at their own risk.

Field and Laboratory Investigation

As requested, subsurface conditions for this ground storage tank were evaluated with a single

core boring at the location staked in the field by the client. This location is presented on Plate 1.

The boring was drilled using a truck-mounted rig equipped with continuous flight augers and wet

rotary techniques. Drilling and sampling were done in general accordance with ASTM methods

and standards. Relatively undisturbed samples of cohesive soil and weathered shale were

obtained with three-inch diameter thin-walled Shelby tubes. Upon encountering the unweathered

strata, the hole was flushed of all cutting, temporary casing inserted and the rock cored near

continuous using an Nx-size, carbide tipped bit.

Core Recovery and Rock Quality Designation (RQD) were measured and recorded. The RQD value

provides an estimate of the variation of rock mass properties. RQD is calculated by summing the

length of all pieces of intact rock core greater than twice the diameter and dividing by the total length

drilled. Pieces shorter than twice the diameter broken mechanically (drilling) or by handling were

fitted together and considered as one piece. RQD is recorded on the "Log of Boring" illustration.

Water levels were estimated during drilling and upon completion of the boring. The water levels

noted during drilling are presented on the “Log of Boring” illustration. A shallow piezometer was

installed post-investigation to a depth of 15 feet adjacent to the location of Boring 1.

Observations from this piezometer are presented in the Surface and Subsurface Conditions

section.


- 2 -

All samples were transported to the central laboratory for visual classification and testing. Soils

were visually classified according to the Unified Soil Classification System (USCS). Rock

materials were described using standard geological nomenclature. The Boring Log and a key to

terms and symbols used on the log are attached.

To aid in the classification process, Atterberg Limits (ASTM D-4318) and Moisture Content

determinations (ASTM D-2216) tests were performed on representative samples. All of the

above test data are summarized on Plate 2.

The potential for heave was also evaluated using the Absorption Pressure-Swell test. This test

involves placing a 1-inch thick sample of soil in a 2.5-inch ID confining ring into a consolidation

machine and inundating it with water. Weight is added in appropriate increments to maintain the

original height and volume of the sample. Once the sample has “balanced”, the weight is

reduced to approximately 200 psf and the soil allowed to swell. Results of these tests are

summarized on Plate 3.

The strength of each cohesive sample was estimated using a hand penetrometer. The results of

these estimates are recorded graphically on the "Log of Boring" illustrations. The strength properties

of selected soil samples were investigated by Unconfined Compression tests. In the Unconfined

Compression test, axial load is applied to a laterally unsupported cylindrical sample until failure

occurs within the sample. This test is conducted fairly rapidly (failure within about 10 minutes) and

generally conforms to ASTM D 2166 for soil samples and D 7012 for rock core. Results of the

Unconfined Compression tests performed are summarized on Plate 3.

Unconsolidated-undrained multi-stage triaxial compression tests were performed on selected

samples of the clay and weathered shale materials. In this test, performed in general accordance

with ASTM D 2850, a cylindrical sample is enclosed in a membrane and subjected to a confining

pressure of about one-half the estimated overburden pressure. The sample is loaded axially to

incipient failure while not permitting drainage from the specimen. Upon reaching incipient failure, the

confining pressure is doubled and the specimen again loaded to incipient failure. This process is

repeated a third time and the sample is loaded past failure. The results of this test are presented

graphically on Plates 4 and 5 as stress-strain curves and Mohr’s diagrams.

The potential for settlement of the subgrade materials was evaluated using the consolidation test

(ASTM D- 2435). In this test a 1-inch thick sample of soil is placed into a 2.5-inch ID confining

ring and inserted into a consolidation machine and loaded to approximately 100 psf. Water is

then supplied to the sample and additional weight is added to ensure the clay sample does not

swell and change volume. After enough load has been applied to ensure the soil does not swell,

additional loads are added incrementally to consolidate the soil. Once the consolidation is

achieved, the sample is decrementally unloaded until the initial weight is achieved. Graphical

representation of changes in void ratio versus changes in vertical stress, and the change in height

of the samples for each applied load compared to elapsed time are presented on Plates 6

through 11.


- 3 -

Surface and Subsurface Conditions

Surface Conditions

At the time of the field investigation the area of the proposed tank was occupied by an existing,

ground-supported steel tank. Surface grades in this area were relatively flat.

Geologic Setting

Review of geologic maps indicates the proposed ground storage tank is located within the Lower

Ozan Formation, which is of the Cretaceous age and consists of dark to medium gray shale in the

unweathered state. The Ozan is calcareous in nature and upon weathering becomes lighter in

appearance and develops the properties of highly plastic (CH) clay. Progressive weathering

produces both CH and moderately plastic (CL) residual clays.

The residual soils are known to be expansive, while the activity of the weathered strata varies.

Subsurface Conditions

The specific type, depth, and thickness of materials penetrated by the borings are reflected on the

individual “Log of Boring” illustrations, which follow the illustrations for this report.

Dark brown, grading with depth to brown and light brown clays were encountered at the surface

and extended to a depth of 14 feet at the boring location. Olive-brown and light gray weathered

shale was present directly below the upper clays and continued to a depth of 54 feet. This shale

was calcareous and soft (rock hardness classification), and contained some gypsum seams

below a depth of 39 feet.

Slightly weathered shale was present at an elevation of 54 feet from the surface. This layer was

gray in appearance and soft, and contained some iron staining. Firm, gray unweathered shale

was noted at a depth of 60 feet. This shale material was fossiliferous and extended through the

termination depth of 70 feet.

The residual clays varied from dry to moist with depth at the time of sampling, while the

weathered shale was generally dry.

Ground water was noted a depth of 50 feet below existing grades during drilling. Just prior to

coring the water level had risen to 5 feet from the ground surface. Observations of the shallow

piezometer are presented in Table 1.

Table 1 Piezometer Readings for Nortex Ground Storage Reservoir

Towngate Drive – Wylie, Texas

Date Read Depth to Ground Water from Surface (ft.)

3/28/16 Installed / Dry

4/04/16 13.9

Rain 4/09/16 and 4/11/16

4/11/16 6.9

Rain 4/17/16

4/18/16 3.7

4/25/16 4.7


- 4 -

Based on this information, ground water should be anticipated as shallow as 3.7 feet from existing elevations during construction. Seismic Classifications

Based on the materials encountered within the borings and the geologic setting, this site may be -

classified as Seismic Class B according to the 2015 International Building Code and ASCE 7-10

as the soils and rock formations most closely match that designation.

Tank Pad Preparation

Ground supported storage tanks constructed over expansive soils will experience both heave as

a result of swelling from the clays, and also settlement due to foundation loads imposed by the

perimeter footing and contents of the tank.

Soil movements were evaluated using the TxDOT Method Tex-124-E “Method for Determining

Potential Vertical Rise of Soils”, and the results of the consolidation and absorption pressure-

swell tests. The TxDOT method is based on the results of a series of pressure-swell tests

performed on samples of varying moisture content and Plasticity Indices (PI), and uses the PI and

measured moisture contents of the samples in question.

In an open environment, movement within residual clay soils is generally seasonal in nature.

Heave occurs during periods of increased rainfall as a result of the clays gaining in moisture and

swelling. During hotter, drier months these same soils will lose moisture and subsequently

shrink. Soil movements are typically manifested as a gradual and sustained heave as the

subgrade clays gain moisture because of lack of evaporation. Also contributing to this heave can

be the infiltration of water from the exterior or from utility leaks and seepage from the tank.

Based on the heave analysis, total soil movements related to the underlying clays and weathered

shale were estimated to be on the order of 5 inches, or more, if soil supported elements are

placed over a relatively dry subgrade. If placed over a relatively moist subgrade, soil movements

were estimated to be on the order of 1 inch. Under current moisture conditions, the potential for

heave was estimated to be in the order of 4 inches.

The potential for settlement was evaluated based on the results of the consolidation test and the

anticipated applied loads from the tank footing and floor slab. Based on this analysis, total

settlement on the order of 1 inch at the tank center, and 2 inches at the perimeter are possible.

Anticipated total differential settlement between the center and tank edge is estimated to be on

the order of 1-1/2 inches.

In order to reduce the potential for heave to the order of 0.7-inch or less, it is recommended that a

minimum of 6 feet of granular fill be placed beneath the tank pad. The depth of the granular fill

should extended at least 5 feet below the perimeter footing.

The area of the tank should be excavated to a depth of 6 feet below the interior floor and 5 feet

below the perimeter footing. This excavation should extend a minimum of 5 feet beyond the

perimeter of the tank. The depth of excavation should be uniform across the area of the tank.


- 5 -

The sidewalls of the excavation should be constructed using an approximate 2-foot wide step and

bench.

The exposed subgrade at the base of the excavation should be ripped to a depth of 6 inches and

compacted per the Earthwork Recommendations section. A minimum 30-mil thick plastic liner

should be placed over the base of the excavation. This is to limit the infiltration of water into the

clay subgrade. The plastic liner should extend up the sidewalls of the excavation as well.

Granular fill used below the storage tank, this material should meet the gradation requirements of

ASTM C33, Size 357. A below grade drainage system should be placed around the perimeter of

the tank pad and below the depth of the granular fill, or the tank excavation sloped to drain to a

central sump. Water that collects within this drainage system should be discharged away from

the tank.

Proper placement of granular fill beneath the tank pad is estimated to limit the potential for heave

to the order of 1 inch over the life of the structure. Total settlement of the perimeter footing is also

estimated to be on the order of 1 inch for a properly compacted subgrade and footings sized

according to the Foundations Recommendations section of this report. Total differential

settlement between the tank center and edge is anticipated to not exceed 0.7 inch.

If construction of the tank pad will be delayed for more than 30 days after it is recommended that

a plastic barrier be placed over the conditioned soils to limit the loss of moisture within the

modified subgrade. This will also limit the infiltration of water from the tank into the subgrade

materials.

All existing foundations and utilities within the proposed tank pad should be removed and the

excavations backfilled using on-site soils or similar. Materials should be placed as outlined in the

Earthwork Recommendations section.

Excavations

Per Federal regulations, any excavation over 20 feet in depth will require an engineered

excavation and safety plan prepared by a licensed engineer. Soils encountered at this site

consisted of CH clays and weathered shale. It is recommended that these materials be treated

as Type B materials per OSHA Excavation Standards CFR 29, Part 1926, Sub-Part P, Appendix

A. For these soils, temporary excavations should be sloped back on a temporary maximum slope

of 1H:1V.

For any temporary retention system design, the clays and shale may be considered to exert an

equivalent fluid pressure of 50 pcf considering drained and active conditions against any shielding

or temporary shoring.

All spoils and construction materials should be kept a minimum of 4 feet from the edge of the

trench. Water should not be allowed to pond along the edge of or within the bottom of any

excavation.


- 6 -

Foundation Recommendations

It is anticipated that a shallow foundation, as described in ACI 372R-03, consisting of a

membrane floor slab with monolithic perimeter wall footings, would be used for support of the

tank. For this site, an allowable net bearing pressure of 4,000 psf may be used when evaluating

the foundation. This value includes a Factor of Safety of at least 3 with respect to the shear

strength of the underlying soils. All foundations should bear a minimum of 36 inches below

existing or finished grade, whichever is deeper.

The tank floor should be designed to not exceed a contact pressure of 3.0 ksf, while the perimeter

footing should not exceed an allowable contact pressure of 5.0 ksf. The footing should have a

minimum width of 3 feet and a maximum width of 5 feet. This office should be allowed to

evaluate the allowable contact pressure in the event the footing width will exceed 5 feet.

The footing and floor slab should bear directly on compacted granular fill as described in the

Tank Pad Preparation and Earthwork Recommendations sections of this report.

Construction Considerations

The foundation should be placed in proper plan location and the excavation cleared of all loose or

soft materials prior to concrete placement. Reinforcing steel cages should be prefabricated in a

rigid manner to allow expedient placement of both steel and concrete into the excavation. It is

essential that excavation of foundation elements and the placement of reinforcing steel and

concrete be carried out in a continuous operation. No portion of the stratum providing structural

support should be exposed to atmospheric conditions for more than eight (8) hours following the

completion of excavation and backfilling operations. If this time requirement cannot be met, it is

recommended that the base of any completed excavation be protected by placing a thin seal slab

of lean concrete or an approved alternate method of protection. Excavation for the tank should

be made with attention to drainage to keep the base of the excavation from collecting water

during wet weather periods. Permanent drainage should be maintained to provide the means of

removing water from the backfill materials during and after construction of the tank. It is

recommended that the subgrade below any granular material beneath the tank be sloped to drain

by gravity to a central collection sump and then collected and discharged away from the structure.

A minimum 30-mil thick plastic sheeting is recommended between the subgrade and granular

material.

In order to confirm compliance with specifications and acceptability of the bearing stratum, a

qualified and experienced geotechnical observer from this office should be present during

foundation installation.

Paving Recommendations

Asphalt Pavement:

Flexible asphalt pavement may be used for parking and drives. The upper six inches of subgrade

below asphalt pavement should be stabilized using approximately 8% hydrated lime (32 pounds

per square yard) to achieve a treated soil with a Plasticity Index of 15 or less. It is recommended

that site specific testing of the subgrade be performed to evaluate the actual amount of lime

required to provide a stabilized subgrade. Lime should be placed in general accordance with


- 7 -

Item 301.2 LIME TREATMENT the North Central Texas Council of Government (NCTCOG)

Standard Specifications for Public Works Construction published in 2004. Lime treated soils

should be compacted to a minimum of 95% of the maximum dry unit weight (ASMT D-698) with

moisture contents at or above optimum.

For light truck and car traffic the following section is recommended:

1” Type D Asphalt Surface Course over,

2” Type A or B Coarse Graded Base Course.

For heavy truck traffic the following section is recommended:

2” Type D Asphalt Surface Course over,

4” Type A or B Coarse Graded Base Course.

All asphalt should be placed in accordance with Item 302 of the NCTCOG standard. Compaction

tests and air void verification should be conducted to evaluate the in-place density of the asphalt

pavement.

All joints within asphalt pavements should be sealed and maintained to limit water infiltration into

the subgrade soils.

Concrete Pavement:

Sections for reinforced concrete paving were evaluated using the Interim AASHO and PCA

methods1. Considering light vehicular traffic and less than six, fully loaded trucks per day, the

following sections are recommended for a 20-year life span.

For light truck and car traffic the following section is recommended:

5” of 3,000 psi Portland Cement Concrete over,

6” of recompacted subgrade.

For heavy truck traffic up to 6 vehicles per day the following section is recommended:

6” of 3,000 psi Portland Cement Concrete over,

6” of recompacted subgrade.

Subgrade soils below concrete pavements should be compacted to a minimum of 95% (ASTM D-

698) with moisture contents between 0 and +4 percentage points.

1 Yoder, E.J., and Witczak, M.W., Principles of Pavement Design, 2nd Ed., John Wiley & Sons, Inc., New

York, NY, pp 605 to 608.


- 8 -

Concrete pavement should be reinforced with No. 3 deformed bars on 18-inch centers. No. 4

smooth dowels should be used at expansion and construction joints on 12-inch centers.

Control joints should be installed in the pavement within four hours after concrete has been

placed, not after completion of the pour. Joint spacing and depth should conform to the

recommendations presented in the latest version of Joint Design for Concrete Highways and

Street Pavements, produced by PCA. Spacing between control joints should not exceed 15-feet.

All joints should be sealed and periodically maintained. This will limit the potential for water to

infiltrate into the subgrade.

Expansion joints should consist of doweled keyways, thickened sections, or steel dowels

supported on a non-deteriorating medium such as bituminous mastic or bituminous impregnated

cellulous2. All expansion joints should be filled completely with sealant to the pavement surface.

Earthwork Recommendations

Areas that will receive fill should be stripped of all organic materials and ripped to a depth of 6

inches. The exposed subgrade should then be wetted as necessary and compacted to a

minimum of 95% of the maximum dry unit weight as determined by ASTM D-698. Moisture

content should be a minimum of +2% above the optimum moisture content.

On-site soils used as backfill against the tank or for utility trenches should be placed in maximum

eight-inch loose lifts and compacted to a minimum of 95% of the maximum unit dry weight as

determined by ASTM D-698. Moisture content should be a minimum of +2% above optimum

moisture content.

Any excavated weathered shale used for backfill against the tank or for utility trenches should be

reduced to a nominal diameter of 3 inches and wetted thoroughly to produce a uniform moisture

content throughout the material. Weathered shale should be placed in maximum 8-inch loose lifts

and compacted to a minimum of 95% of the maximum dry unit weight as determined by ASTM D-

698. Moisture contents should be a minimum of +2% of optimum as determined by ASTM D-698.

Granular fill used below the storage tank, this material should meet the gradation requirements of

ASTM C33, Size 357. This material should be placed in maximum 10 inch loose lifts and

compacted to a minimum of 95% of the maximum dry unit weight as determined by ASTM D

4253, Maximum Index Density and Unit Weight of Soils Using a Vibratory Table. Crushed

concrete, crushed stone or crushed pit-run gravel may be used. Material types may not be

mixed.

Granular fill should be tested for density using portable nuclear gauges set in the back-scatter

mode.

2 Guide for Design and Construction of Concrete Parking Lots, ACI Committee 330, NRMCA Publication

MSP 34, January 1988, p 330R-8.


- 9 -

Construction Testing and Observation

It is recommended that all backfill materials within a trench be tested for moisture and density at a

rate of one test per foot of fill for every 100 linear feet of excavation. Field density tests should be

conducted during placement of fill. Provisions should be made to permit safe access to the utility

trench during placement of fill to allow for testing of the backfill materials for adequate moisture

and density.

Density testing beneath the tank pad should be conducted at a rate of one test per lift for every

1,500 square feet of area. This equates to three tests per lift for a 95-foot diameter tank. Field

testing is to be conducted during placement of fill materials.

Periodic inspection of shallow foundations is recommended to ensure adherence with the

recommendations of this report.

PLATE

1

LEGEND

SOIL BORING

HJA No.:

DATE:

15841G

FEBRUARY 2016

TEXAS FIRM REGISTRATION NO. F-1238

BORING LOCATION PLAN

235 MORGAN AVE. DALLAS, TX 75203 I 214.941.3808 I WWW.HJA-ENG.COM

1

NORTEX 1.0MG GROUND STORAGE TANK

TOWNGATE DRIVE

WYLIE, TEXAS

AutoCAD SHX Text

NOT TO SCALE

AutoCAD SHX Text

N

GEOTECHNICAL INVESTIGATION REPORT NO. 15841G

NORTEX 1.0 MG STORAGE TANK TOWNGATE DRIVE

WYLIE, TEXAS

Plate 2

SUMMARY OF INDEX PROPERTIES

BORING NUMBER

DEPTH (ft.)

LIQUID LIMIT (%)

PLASTIC INDEX

DUW

(pcf)

FINER #200 (%)

MOISTURE CONTENT

(%)

UNIFIED SOIL CLASSIFICATION

1 0.0 – 1.0 22.4

1 1.0 – 2.0 32.8

1 2.0 – 3.0 32.5

1 3.0 – 4.0 68 42 89.7 28.2 CH

1 4.0 – 5.0 98.6 23.1

1 5.0 – 6.0 96.9 25.6

1 6.0 – 7.0 92.8 32.8

1 7.0 – 8.0 91.1 30.8

1 8.0 – 9.0 66 43 88.2 26.7 CH

1 9.0 – 10.0 94.5 30.5

1 14.0 – 15.0 91.9 29.0

1 19.0 – 20.0 68 43 97.2 25.6 CH

1 24.0 – 25.0 22.3

1 29.0 – 30.0 23.6

1 34.0 – 35.0 22.7

1 39.0 – 40.0 21.3

1 44.0 – 45.0 104.4 21.6

1 49.0 – 50.0 63 40 102.7 21.4 CH

1 54.0 – 55.0 18.2

1 59.0 – 60.0 17.6

1 60.0 – 62.0 114.5 17.3

1 62.0 – 64.0 114.3 17.3

1 64.0 – 66.0 115.1 16.7

1 66.0 – 68.0 115.2 16.8

1 68.0 – 70.0 115.7 16.6

GEOTECHNICAL INVESTIGATION REPORT NO. 15841G

NORTEX 1.0 MG STORAGE TANK TOWNGATE DRIVE

WYLIE, TEXAS

Plate 3

SUMMARY OF ABSORPTION PRESSURE-SWELL TESTS

BORING NUMBER

DEPTH (ft.)

SWELL PRESSURE

(psf)

GAIN IN MOISTURE

(%)

PERCENT SWELL

(%)

MATERIAL DESCRIPTION

1 3.0 – 4.0 776.0 4.0 0.9 CLAY, hard, olive-brown

1 8.0 – 9.0 970.0 5.5 2.5 CLAY, hard, olive-brown

1 49.0 – 50.0 2,328.0 6.1 3.9 SHALE, soft, weathered, olive-brown

SUMMARY OF UNCONFINED COMPRESSION TESTS - SOIL

BORING NUMBER

DEPTH (ft.)

PEAK STRESS

(psi)

FAILURE STRAIN

(%)


1 4.0 – 5.0 71.6 3.1 CLAY, hard, olive-brown

1 7.0 – 8.0 17.8 4.4 CLAY, hard, olive-brown

1 19.0 – 20.0 53.5 7.7 SHALE, soft, weathered, olive-brown

SUMMARY OF UNCONFINED COMPRESSION TESTS - ROCK

BORING NUMBER

DEPTH (ft.)

PEAK STRESS

(psi)

FAILURE STRAIN

(%)


1 60.0 – 62.0 345.7 1.9 SHALE, firm, gray

1 62.0 – 64.0 339.9 2.3 SHALE, firm, gray

1 64.0 – 66.0 357.2 2.3 SHALE, firm, gray

1 66.0 – 68.0 345.6 2.2 SHALE, firm, gray

1 68.0 – 70.0 346.9 1.7 SHALE, firm, gray

TRIAXIAL COMPRESSION TEST STRESS-STRAIN PLOT

BORING N0.: 1DEPTH (FT.): 5.0-6.0CLAY, slightly silty, dark brown

0 5 10 15AXIAL STRAIN (%)

0

20

40

60D

EV

IATO

R S

TRE

SS

(PS

I)

MOISTURE CONTENT (%): 25.6 DRY UNIT WEIGHT (PCF): 96.9CONFINING PRESSURE (PSI): 5, 10, 20

0 20 40 60 80NORMAL STRESS (PSI)

0

10

20

30

40

SH

EA

RIN

G S

TRE

SS

(PS

I)

TEST TYPE:UNCONSOLIDATED-UNDRAINED TRIAXIAL COMPRESSION TEST (ASTM D 2850)

PLATE 4TEXAS FIRM REGISTRATION NO. F-1238

HJA NO.: 15841G DATE TESTED: 02/28/16


NORTEX 1.0 MG STORAGE TANKTOWNGATE DRIVE

WYLIE, TEXAS

cr = 20 psiΦr = 6 degrees

TRIAXIAL COMPRESSION TEST STRESS-STRAIN PLOT

BORING N0.: 1DEPTH (FT.): 14.0-15.0SHALE, weathered, calcareous, olive-brown and light gray

0 5 10 15AXIAL STRAIN (%)

0

10

20

30

40D

EV

IATO

R S

TRE

SS

(PS

I)

MOISTURE CONTENT (%): 29.0 DRY UNIT WEIGHT (PCF): 91.9CONFINING PRESSURE (PSI): 7, 14, 28

0 20 40 60 80NORMAL STRESS (PSI)

0

10

20

30

40

SH

EA

RIN

G S

TRE

SS

(PS

I)

TEST TYPE:UNCONSOLIDATED-UNDRAINED TRIAXIAL COMPRESSION TEST (ASTM D 2850)

PLATE 5TEXAS FIRM REGISTRATION NO. F-1238




WYLIE, TEXAS

cr = 15.4 psiΦr = 3.5 degrees


CONSOLIDATION TESTVOID RATIO-LOG OF STRESS PLOT

BORING N0.: 1DEPTH (FT): 6.0-7.0CLAY, slightly silty, dark brown

0.1 1 10VERTICAL STRESS (TSF)

0.50

0.55

0.60

0.65

0.70

0.75

0.80

VOID

RAT

IO

e = 0.7818

TEST TYPE: CONSOLIDATION TEST (ASTM D 2435)

1E-0050.0001 0.001 0.01COEFFICIENT OFCONSOLIDATION(SQ CM/SEC)

TEXAS FIRM REGISTRATION NO. F-1238PLATE 6

MOISTURE CONTENT (%): 32.8DRY UNIT WEIGHT (PCF): 92.8



WYLIE, TEXAS


CONSOLIDATION TESTDIAL READING-LOG OF TIME PLOT

BORING N0.: 1DEPTH (FT): 6.0-7.0CLAY, slightly silty, dark brown

0.1 1 10 100 1000 10000TIME (MINUTES)

0.22

0.23

0.24

0.25

0.26

0.27

0.28

0.29

0.30

0.31

0.32

0.33

0.34

0.35

0.36

DIA

L R

EAD

ING

(IN

CH

ES)

1.28 tsf

2.56 tsf

5.12 tsf

10.24 tsf


TEXAS FIRM REGISTRATION NO. F-1238PLATE 7235 MORGAN AVE. DALLAS, TX 75203 I 214.941.3808 I WWW.HJA-ENG.COM


WYLIE, TEXAS



BORING N0.: 1DEPTH (FT): 9.0-10.0CLAY, slightly silty, brown to light brown

0.1 1 10VERTICAL STRESS (TSF)

0.50

0.55

0.60

0.65

0.70

0.75

0.80

VOID

RAT

IO

e = 0.7511


1E-005 0.0001 0.001COEFFICIENT OFCONSOLIDATION(SQ CM/SEC)





WYLIE, TEXAS



BORING N0.: 1DEPTH (FT): 9.0-10.0CLAY, slightly silty, brown to light brown

0.1 1 10 100 1000 10000TIME (MINUTES)

0.24

0.25

0.26

0.27

0.28

0.29

0.30

0.31

0.32

0.33

0.34

0.35

0.36

DIA

L R

EAD

ING

(IN

CH

ES)

1.28 tsf

2.56 tsf

5.12 tsf

10.24 tsf




WYLIE, TEXAS



BORING N0.: 1DEPTH (FT): 44.0-45.0SHALE, weathered, calcareous, olive-brown and gray

1 10VERTICAL STRESS (TSF)

0.40

0.45

0.50

0.55

0.60

VOID

RAT

IO

e = 0.5852


0.0001 0.001 0.01COEFFICIENT OFCONSOLIDATION(SQ CM/SEC)





WYLIE, TEXAS



BORING N0.: 1DEPTH (FT): 44.0-45.0SHALE, weathered, calcareous, olive-brown and gray

0.1 1 10 100 1000 10000TIME (MINUTES)

0.26

0.27

0.28

0.29

0.30

0.31

0.32

0.33

0.34

0.35

0.36

DIA

L R

EAD

ING

(IN

CH

ES)

2.56 tsf

5.12 tsf

10.24 tsf

20.48 tsf




WYLIE, TEXAS

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