CONSULTING SERVICES

NEW GRIT REMOVAL FACILITY

MUDDY CREEK WWTP

SAYLER PARK, OHIO

Prepared for: Jacobs Engineering Group, Inc. Thelen Project No.: 110187E

Copyright by Thelen Associates, Inc.

February 1, 2013 Jacobs Engineering Group, Inc. 1880 Waycross Road Cincinnati, Ohio 45240 Attn: Ms. Debbie Schafer, P.E. Re: Consulting Services New Grit Removal Facility Muddy Creek WWTP Sayler Park, Ohio Ladies and Gentlemen:

This letter is the report of our geotechnical exploration for the proposed new Grit

Removal Facility to be constructed at the Metropolitan Sewer District of Greater

Cincinnati‟s Muddy Creek Wastewater Treatment Plant (WWTP) in Sayler Park, Ohio.

Our services were authorized under the terms and conditions of Jacobs Engineering

Group, Inc. (Jacobs) Subconsultant Agreement No. C8X94100-S11-0002 (dated

January 11, 2011) to Master Services Agreement No. 95X10643 (dated September 11,

2009).

SCOPE

The scope of our services, as amended by Jacobs, included review of original structural

drawings 20-24, prepared by Bonham, Grant & Brundage, Ltd. for the Muddy Creek

WWTP‟s Preliminary Treatment Unit (PTU), dated January 1971; review of driven pile

specifications, and available pile driving records for the PTU; assembly and review of

test boring logs drilled at the Muddy Creek WWTP by Thelen Associates, Inc. (Thelen)

and the H.C. Nutting Company (HCN); review of the Modified Top Plan, Drawing No. C-

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8, prepared by the BBS Corporation, dated July 2003, further modified by Jacobs to

show the proposed PTU modifications; an engineering evaluation of the likely driven pile

capacity; recommendations for foundation design; and preparation of this consulting

services report.

PROJECT DESCRIPTION

The Muddy Creek WWTP‟s Preliminary Treatment Unit was designed in January 1971.

The PTU included two side-by-side, cast-in-place concrete, preaeration tanks that total

90.0 feet by 55.0 feet in plan dimensions. The tanks are oriented northeast to

southwest.

The tops of the exterior walls are at El. 484.25 feet (mean sea level [MSL] datum), and

the floors slope from Els. 467.0 to 466.0 feet. The Piling Plan and Details drawing,

Sheet 20, called for the tanks to be supported on mandrel-driven, concrete-filled,

closed-end, steel piles. The steel casing was to be circular, corrugated, and either step-

tapered or “parallel sided” (i.e., of constant diameter). Step-tapered piles were to have

minimum diameters of 9 inches at the driving shoe and 13 inches at the cutoff elevation.

The rate of taper was to be no more than 1/8 inch per foot of pile. “Parallel-sided” steel

shells were to have a minimum 12 inch diameter. The steel casings were to be of

minimum 14 gauge steel. The pile tops (i.e., top of steel casing) were to be set 8 inches

above the base slab elevations specified on the drawing. Pile spacings vary from 3.5 to

6.6 feet, center-to-center.

The piles were to be reinforced with four vertical #6 bars; the reinforcement lengths

were based on whether or not an individual pile was also to be used to resist uplift

forces. Reinforcing steel was to meet the requirements of ASTM A615, Grade 40. The

cast-in-place concrete was to have a minimum 28-day compressive strength of 3,750

pounds per square inch (psi).

The piles were to be driven with a steam, air, or diesel hammer delivering at least

19,000 ft-lb of energy per blow. The hammer used by Goettle, Inc. to drive the piles

was a Link Belt 440, which has a rated energy of 18,200 ft-lb per blow.

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The specifications required the piles to be driven at least 25 feet and to have a “safe

bearing load” of at least 25 tons. Uplift piles were to have a “safe uplift load” of at least

15 tons. One of the piles in Preaeration Tank No. 1 was designated as an uplift test

pile. The specifications required the uplift test pile to be loaded in 5-ton increments to a

total load of 30 tons. The pile was to be accepted for uplift if after 48 hours from

application of the final increment, its measured deflection did not exceed 0.01 inch per

ton of applied test load.

One of the piles in Preaeration Tank No. 2 was designated as a compression test pile.

The specifications required the compression test pile to be loaded in 8.33-ton

increments to a total load of 50 tons. The pile was to be unloaded in 15-ton increments

only after 48 hours had passed without more than 0.01 inches of further settlement

occurring. The test pile was to be accepted for compression if the net settlement after

deduction of rebound did not exceed 0.25 inches. We understand that the load test

records are no longer available.

The pile driving records do not specify the pile diameter, but do indicate that Hel-Cor

(“helically corrugated”) pipe was used. The driving records indicate that pay lengths for

the PTU piles varied from 32.0 to 37.0 feet. The final inch of driving for all but 16 of the

233 piles ranged from 16 to 100 blows/inch, presumably in the bedrock; for the

remaining 16 piles, the pile tips did not move upon encountering the bedrock. The pile

tip elevations generally vary from Els. 428 to 433 feet.

The plans did not call for full-length reinforcement of the piles. They called for four #6

bars to be 11.5 feet long and to have #3 ties spaced at 1.33 feet. In addition, a #6 bar

with a 4-foot splice was to run to the bottom of the pile. A second #6 bar with a 4-foot

splice was to run to a depth of L/4 (i.e., length/4) off of the bottom. A third #6 bar with a

4-foot splice was to run to a depth of L/2 off of the bottom. The pile driving records

include the weight of reinforcing steel in each pile; the weights suggest that each pile,

as constructed, includes four #6 bars that run full length.

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The preaeration tanks are no longer in use. MSDGC desires to convert the tank area

into new grit removal facility. A new grit building is to be constructed over the southwest

end of Tank No. 1. The building will be 32 feet long, 25 feet wide, and 15 feet tall, and

will include a dumpster area and two Slurry Cup and Grit Snail units. The remainder of

Tank No. 1 will be used for storage. The southwest end of Tank No. 2 will contain two

head cells and three grit pumps. The northeast end of Tank No. 2 will be filled with

concrete. The wall-mounted channels of the former preaeration tanks are to be used for

grit influent, grit bypass, and grit effluent channels. Design floor and feature elevations

are not known at this time.

The Project Structural Engineer is basing his grit removal facility design on an assumed

safe compression capacity of 25 tons per pile, and on an assumed safe uplift capacity of

15 tons per pile. Jacobs has requested confirmation of these safe working pile loads,

as well as recommendations concerning the Seismic Site Class per the 2011 edition of

the Ohio Building Code (OBC 2011).

SEISMIC REQUIREMENTS OF OHIO BUILDING CODE

All commercial building project plans and specifications are required to meet the seismic

requirements of OBC 2011, which defines the Maximum Credible Earthquake as that

seismic event having a 2 percent probability of exceedance in any 50-year period as the

basis for seismic design. OBC 2011 also requires that local site geology, including

overburden soils above the bedrock, be factored into the determination of seismic

parameters to be used in structural design. The effects of regional seismicity (as

mandated by OBC 2011) have been considered in this study and will be addressed later

in this report.

SUBSURFACE CONDITIONS

The test boring locations referenced in this report are shown on the Boring plan,

Drawing 110187E-1 in the report Appendix.

Jacobs has provided logs of Borings 22 through 39, drilled by HCN between July 7 and

August 18, 1969 for the 1971 plant addition that included the preaeration tanks.

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However, no boring plan was made available. Based on a plant stationing system

included on a 1995 Existing Site Plan prepared by the BBS Corporation, Borings 22

through 39 appear to be located within the limits of the aeration tank, secondary settling

tank, chlorine contact tank, sludge concentration building, and secondary clarifier areas,

all located northwest of the proposed grit removal facility location. These borings

indicate that the bedrock surface varies from El. 451.4 feet in the secondary settling

tank area (Boring 26, S1+90, W9+00) to El. 431.0 feet in the sludge concentration

building area (Boring 31, S4+30, W5+70). The bedrock surface appears to be dipping

to the southeast. Thelen Boring 95004E-3, drilled in the Ohio River southwest of the

new grit facility removal location, encountered the bedrock surface at El. 422.7 feet,

indicating that the bedrock elevation continues to slope downwards to the south and

southeast beyond the preaeration tank areas. These bedrock surface elevations in the

borings appear to be consistent with the preaeration tank pile tip elevations, which

generally varied from Els. 428 to 433 feet.

The test boring logs are included in the report Appendix. A Soil Classification Sheet is

also included, which describes the terms and symbols used on the Thelen log.

The test borings indicate that the overburden soils above the bedrock generally consist

of combinations of brown and gray, moist to very moist, soft to very stiff, silty clay and

sandy, silty clay with fine sand lenses; gray, very moist, very loose, clayey silt with fine

sand lenses; brown and gray, wet, loose to medium dense, silty and clayey, fine to

coarse sand and gravel; and gray, wet, very loose to dense, silty fine sand with cobbles.

SPT „N‟ values in the cohesive soils ranged from 2 to 28 blows/foot. SPT „N‟ values in

the noncohesive soils ranged from 2 to 69 blows/foot. The cohesive soils included man-

placed site fill ranging in thickness from 1.5 to 19.5 feet.

Free subsurface water was noted in the borings during drilling at elevations ranging

from 449.6 to 475.0 feet, and at completion at elevations ranging from 465.0 to 479.4

feet. Free subsurface water levels varied from Els. 460.1 to 478.2 feet at times ranging

from 2.5 hours to 20 days following the completion of drilling.

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CONCLUSIONS AND RECOMMENDATIONS

The conclusions and recommendations of this report have been derived by relating the

general principles of the discipline of Geotechnical Engineering to the proposed

construction outlined by the Project Description section of this report. Because changes

in surface, subsurface, climatic, and economic conditions can occur with time and

location, we recommend for our mutual interest that the use of this report be restricted

to this specific Grit Removal Facility project.

Our understanding of the proposed construction is based on a series of emails

exchanged between the writer, Ms. Debbie Schafer, P.E. of Jacobs Engineering Group,

Inc., and Mr. Michael R. Patterson, P.E. of Jacobs Engineering Group, Inc.; and also on

our review of specific plan sheets described in the Project Description section of this

report. We recommend that our office be retained to review the final design documents,

plans, and specifications to assess any impact that changes, additions, or revisions in

these documents may have on the conclusions and recommendations of this report.

Any changes or modifications that are made in the field during the construction phase

that alter site grading, structure location, infrastructure, or other related site work should

be reviewed by our office prior to their implementation.

If conditions are encountered in the field during construction that vary from the facts of

this report, we recommend that our office be contacted immediately to review the

changed conditions in the field and to make appropriate recommendations.

The scope of our services did not include any environmental assessment or

investigation for the presence or absence of wetlands or hazardous or toxic materials in

the soil, bedrock, surface water, groundwater or air, on or below or around this site.

We reviewed available test boring logs for our evaluation of the site conditions and for

the formulation of the conclusions and recommendations of this report. We assume no

responsibility for the interpretation or extrapolation of the information by others.

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Based on our engineering reconnaissance of the site, the available test boring logs and

pile driving records, our understanding of the existing and proposed construction, and

our experience as Consulting Soil and Foundation Engineers in the Greater Cincinnati

Area, we have reached the following conclusions and make the following

recommendations.

Subsurface Conditions and Seismicity

1. The available test borings define a subsurface profile consisting of very stiff, silty

clay fill soils underlain by stiff to very stiff, silty clay native soils; soft to medium

stiff, silty clay native soils; loose to medium dense, silty fine sands; and the shale

and limestone bedrock. Free subsurface water levels varied from Els. 460.1 to

478.2 feet at times ranging from 2.5 hours to 20 days following the completion of

drilling.

2. Based on OBC 2011, it is our opinion that the following seismic parameters

shown below are applicable to the proposed grit removal facility site.

Occupancy Category (assumed) III Site Class D Fa 1.6 Fv 2.4 SS 0.144 g (USGS website) S1 0.080 g (USGS website) SMS 0.230 g SM1 0.192 g SDS 0.154 g SD1 0.128 g Seismic Design Category B

The Occupancy Category shown (III) assumes that the Muddy Creek WWTP is

not considered an “essential facility”. If the Muddy Creek WWTP is designated

as an essential facility, the Occupancy Category becomes IV and the site would

be assigned to Seismic Category C. The determination as to whether or not the

Muddy Creek WWTP is to be designated an “essential facility” is to be made by

MSDGC.

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Existing Pile Capacity

3. The piles in the preaeration tanks were required to have respective minimum

allowable compressive and uplift capacities of 25 and 15 tons, and respective

minimum ultimate compressive and uplift capacities of 50 and 30 tons. However,

the Contractor was only required to load them to twice the design load, or 50 tons

compression / 30 tons tension. Because the Contractor was not required to load

the test piles to failure, we can only assume that the piles were successfully

tested to a compressive load of 50 tons and to an uplift load of 30 tons. The

ultimate capacities of the piles may be greater, but the load tests were not

required to show how much greater.

4. The weights of steel reinforcement indicated on the pile driving records suggest

that each pile was constructed with a full-depth, steel reinforcing cage, which

would appear to exceed the pile design requirements shown on Sheet 20 (Piling

Plan and Details). However, this may have been done to gain the required

ultimate pile capacities with a smaller-diameter pile.

5. Comparison of the pile tip elevations with the HCN boring logs indicates that the

piles were driven to refusal on or slightly below the bedrock surface. The piles

were driven with a Link Belt 440 hammer, which has a rated energy of 18,200 ft-

lb. The piles were driven to their final penetrations at rates of at least 16

blows/inch. A simple analysis indicates that piles driven with that rated energy

and at those final penetration rates may have ultimate capacities of about 120

tons. Applying a safety factor of 3.0, which is appropriate when load test data

are not available, would yield an allowable compressive capacity of 40 tons.

6. Based on the pile driving records, the hammer rating, and the presence of the

shale and limestone bedrock, it is our opinion that the existing piles have higher

ultimate compressive capacities than 50 tons, even if they are 12-inch-diameter

piles. However, regardless of the actual pile diameter, Section 1810.3.3.1.1 of

OBC 2011 limits driven piles to allowable compressive capacities of 40 tons in

the absence of load test data.

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7. In our opinion, the existing piles may be utilized for allowable compressive loads

of 40 tons and for allowable uplift loads of 15 tons. If higher capacities are

desired, load testing will be necessary as per Section 1810.3.3.1.1 of OBC 2011.

8. Dynamic, non-destructive load testing may be performed on any of the existing

piles that can be exposed for testing. Dynamic pile testing would require that the

pile be exposed by removing a portion of the existing concrete slab, cutting off

the existing hook bar dowels, and excavating about 2 feet of soil from around the

pile so that testing gauges can be attached. The testing could then be completed

using a portable, low-headroom, hydraulic impact hammer such as the American

Piledriving Equipment, Inc. (APE) Model 7.5c or approved equivalent. This

hammer can be lifted and moved using a forklift; both the hammer and forklift

would need to be lowered into the existing tank with a crane. The APE Model

7.5c has a maximum rated energy of 15,200 ft-lb.

9. Assuming that the pile layout shown on Sheet 20 is correct, the largest area

supported by any existing pile within the proposed concrete infill area of

Preaeration Tank No. 2 is 32.5 ft2 (6.29 ft X 5.17 ft). The maximum fill height is

18.25 feet, assuming that the area is to be filled to the top of the wall. This would

impose a maximum load of 44.5 tons on the most widely-spaced piles along the

southeast tank edge; this exceeds the maximum allowable compression load by

a little over 11 percent. Options are to a) use a lightweight concrete fill product

that would need to have a density at or below 135 pounds per cubic foot (pcf); b)

backfill the area with compacted and tested fill; or c) limit the height of concrete

backfill in the tank such that the 40-ton allowable compressive load will not be

exceeded.

Other Considerations

10. The concrete infill in Preaeration Tank No. 2 will need to be placed in lifts to

avoid overstressing the central wall that separates the tanks.

11. If compacted and tested fill is used to backfill the proposed infill area of

Preaeration Tank No. 2, we recommend that it meet the requirements of

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structural fill. Clayey fill should be placed in maximum 12-inch lifts, and should

be compacted with appropriate equipment to at least 95 percent of the maximum

dry density obtained by the standard Proctor moisture-density test (ASTM D698),

at moisture contents within 3 percent of the optimum moisture content. Granular

fill should be placed in maximum 8-inch lifts, and should be compacted with

appropriate equipment to at least 75 percent relative density as per the ASTM

D4253/D4254 Test Methods. Fill materials should not include trash, debris,

organic matter, frozen materials, or any other deleterious materials.

12. If clayey backfill is used, we recommend that a manufactured drainage mat be

placed against the tank walls prior to backfill placement. The drainage mat

should extend no higher than 24 inches below the top of the fill. The base of the

mat should be hydraulically connected to a minimum 4-inch-diameter, rigid,

perforated (perforations down), PVC pipe connected to a sump or gravity outlet.

The pipe should be surrounded by at least 6 inches of free-draining, granular fill

containing no more than 3 percent fines. A filtration geotextile such as Mirafi

140N (or approved equivalent) should separate granular fill materials from any

clayey backfill to prevent migration of fines into the drain.

13. If granular backfill is used, the manufactured drainage mat will not be necessary

as long as the fill material is free draining (i.e., contains less than 3 percent

fines). The granular fill will still require permanent drainage.

14. A November 4, 2011 e-mail from Mr. Patterson notes that Sheet 20 called for 230

piles, while the driving records indicate that 233 piles were installed. The writer‟s

review of the pile driving records indicate that only 230 of the piles were included

in the final pay length quantity, suggesting that perhaps the three extra piles were

rejected for some reason.

APPENDIX

ASFE Report Information

Boring Plan, Drawing No. 110187E-1

HCN Test Boring Logs

Thelen Test Boring Logs, Project No. 95004E

Soil Classification Sheet

95004E-1

95004E-3

(422.7)

39

22

23

(439.6)

24

(439.1)

26

(451.4)

27

(437.5)

28

(438.7)

30

(449.1)

29

(438.3)

31

(431.0)

32

(432.6)

33

(433.9)

34

(434.6)

3536

37

38

HCN 99-2

(432.2)

HCN 97-1

PROPOSED GRIT

REMOVAL FACILITY

LOCATION

270' (N

.T

.S

.)

HCN 99-1

(430.9)

Scale:

Date:

Drawing No.:

Title:Project:

Client:

Location:

Notes

1398 Cox Avenue, Erlanger, Kentucky 41018 / 859-746-9400Lexington, Kentucky • Cincinnati, Ohio • Dayton, Ohio

BORING PLAN

BASE MAP TAKEN FROM SITE PIPING PLAN, SHEET CU-101,

BY JORDAN, JONES & GOULDING, DATED FEBRUARY 2011

Jacobs Engineering Group, Inc.

Consulting Services

MSDGC Muddy Creek WWTP

Grit Removal Facility

Sayler Park, Ohio

1" = 100'

1/31/2013

110187E-1

INDICATES THELEN TEST BORING (PROJECT NO. 95004E)

INDICATES HCN TEST BORING LOCATIONS

INDICATES BEDROCK SURFACE ELEVATION (FT.)

(439.1)