A 1 1. Ai [>y^i’'‘cHi^?^

A Study of Work Practices

Employed to Protect Wqrkers in

Trenches

Jimmie Hinze and Nicholas J. Carino

Structures and Materials Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington. D.C. 20234

March 1 980

Sponsored by:

Department of Labor

Occupational Safety and Health Administration

Washington, D.C.

HATIONAL Btm£AU

or stamdakm

UBBAST

NBSIR 80-1988 5£p jg 1980

Xl

A STUDY OF WORK PRACTICES

EMPLOYED TO PROTECT WORKERS IN

TRENCHES

/ - 5b

Jimmie Hinze and Nicholas J. Carino

Structures and Materials Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U S. Department of Commerce

Washington, D.C. 20234

March 1980

Sponsored by:

Department of Labor

Occupational Safety and Health Administration

Washington, D.C.

U S. DEPARTMENT OF COMMERCE, Philip M. Klutenick, Secretary

Luther H. Hodges. Jr., Deputy Secretary Jordan J. Baruch. Assiamnt Stcntuy for Sci»ne, ond Tochnology

NATIONAL BUREAU OF STANDARDS. Ernaat AmWar. Diroctor
if

, '^. .> ' , ^

;

'

. f-jf Q

"* ,"'^‘

, , ,V *'! • MV1 ^ *

<IA3MS» vUAor.'M

*04U«SUT»%0

v«Aa^ ^

• (/. •;

08® « I <»32

-r ;;'t. -V* »'•<!

4

I '"41^

»'

I' #

«»>.i-'' w> i * ^''

' ^'r#. .;^ m

(IJ SSr"^ £'< »'4

»«. , 'f

•,^,ii,># i/!

'

.Hfc. , i«tV,. X^u'ni>A!4#(«»^i ! <tj^

'

„ ji,-

^ •i>^. - Wlfc!! <2 <i3S^^H

i-i

iff- ‘*'^1

:F. si.

:/! » '

''* ‘**r i'iA

' '.j'tliliiiimilrM - ''

<:Vv4ll

«fv

.a',

Lit;>'ri
TABLE OF CONTENTS

Page

LIST OF TABLES v ACKNOWLEDGEMENTS vi

METRIC (SI) CONVERSION UNITS vii

EXECUTIVE SUMMARY vili

ABSTRACT x

1.0 INTRODUCTION . 1

1 . 1 General 1 1.2 Purpose and Scope 1 1.3 Definitions: Excavation vs. Trench 2

2.0 FIELD INTERVIEWS 3

2.1 Methodology 3

2.1.1 Data Coding 4

2.2 Characteristics of the Industry 5

2.3 Technical Aspects of Trenching 10

2.3.1 Trench Dimensions 10

2.3.2 Construction Practices 11

3.0 FACTORS INFLUENCING SAFETY PERFORMANCE 12

3.1 Company Size 13

3.1.1 The Nature of Large Companies 13

3.1.2 Other Characteristics Affecting Safety 14

3.2 Management Practice 15

3.2.1 Impact of Management Style 15

3.2.2 Cost Information 17

3.2.3 Safety Practices 18

3.3 Type of Trench Protection 20

4.0 NATIONAL UTILITY CONTRACTORS OF AMERICA (NUCA) SURVEY 22

4.1 Characteristics of Companies Responding to the

NUCA Survey 23

4.2 Technical Aspects of Trenching 27

4.3 Impact of OSHA 30

4.4 Safety Programs 33

4.5 Factors Influencing Safety Performance 35

5.0 NATIONAL ASSOCIATION OF PLUMBING, HEATING AND COOLING

CONTRACTORS (NAPHCC) SURVEY 36

iii
TABLE OF CONTENTS (Continued)

Page

6.0 SUMMARY AND CONCLUSIONS 38

7.0 RECOMMENDATIONS 38

REFERENCES 40

APPENDIX

A. RESPONSES TO QUESTIONS RELATED TO FIELD PRACTICES 41

B. RESPONSES TO QUESTIONS RELATED TO SAFETY PRACTICES AND

ATTITUDES 49

C. COMMENTS ON EMPIRICAL PRACTICES 57

D. COMMENTS ON EXCAVATION AND TRENCHING 60

E. NATIONAL UTILITY CONTRACTORS ASSOCIATION (NUCA) STUDY 74

F. NATIONAL ASSOCIATION OF PLUMBING, HEATING AND COOLING

CONTRACTORS (NPHCC) STUDY 84

G. REPORT OF THE BUILDING AND CONSTRUCTION TRADES DEPARTMENT,

AFL-CIO 90

Iv
LIST OF TABLES

Page

Chapter 2: Field Investigation

Table 1 Annual Dollar Volume of Utility Contractors 6

Table 2 Percent of Company Volume of Work That Is Trenching . . 6

Table 3 Amount of Company Work Done Within 50 Miles of the

Home Office • • 7

Table 4 Average Number of Field Employees in the Company 7 Table 5 Number of Home Office Employees 8

Table 6 How Often the Company President Visits the Job 10

Table 7 Typical Trench Depth 11

Table 8 Typical Trench Width 11

Table 9 Length of Open Trench Behind the Backhoe 11

Chapter 4: National Utility Contractors of America (NUCA) Study

Table 10 Annual Dollar Volume of Utility Contractors 23

Table 11 Percent of Company Volume of Work That is Trenching .. 24

Table 12 Amount of Company Work Done Within 25 Miles of the

Home Office 24

Table 13 Average Number of Field Employees in the Company 25

Table 14 Number of Home Office Employees in the Company 26

Table 15 How Often the Company President Visits the Job 26

Table 16 Typical Depth to Water Table 28

Table 17 Typical Trench Depth * 28

Table 18 Typical Trench Width 29

Table 19 Length of Open Trench Behind the Backhoe 29

Table 20 Frequency of Use of Sloping and Different Shoring

Systems 30

Table 21 OSHA Tables P-1 and P-2 31

V
ACKNOWLEDGMENTS

The field study was conducted by the first author and he wishes to

acknowledge the assistance of all parties who assisted In this research

effort. The National Utility Contractors Association was particularly

helpful in voluntarily conducting one survey and In helping to set up

meetings between NBS representatives and utility contracting firms.

Assistance was also received from the Associated General Contractors and

the National Association of Plumbing, Heating and Cooling Contractors.

Many contractors gave many hours of their time to this study. Since

anonymity was assured to all participants, they will remain unnamed, but

their time and efforts will be remembered. Special thanks are due also

to Lawrence A. Salomone of the National Bureau of Standards for reviewing

the report and for his useful comments.

vl
METRIC (SI) CONVERSION UNITS

In view of the presently-accepted practice In this country In this

technological area, common U.S. units of measurement have been used

throughout this paper. In recognition of the position of the U.S. A. as a signatory to the General Conference on Weights and Measures, which

gave official status to the metric SI system of units in 1960, we assist

readers Interested In making use of the coherent system of SI units by

giving conversion factors applicable to U.S. units used in this paper.

Length

1 In = 0.025A meter* (m)

1 ft = 0.3048 meter* (m)

1 mile = 1.609 kilometer

* Exactly

vll
EXECUTIVE SUMMARY

Experience has shown that the Occupational Safety and Health Administration (OSHA) regulations for excavation, trenching and shoring promulgated

in 1974 have been difficult to enforce because of technical weakness

and ambiguities. Consequently in June 1976 OSHA engaged the National

Bureau of Standards, (NBS), to (a) study the compatibility of the technical provisions in these regulations with actual construction practice

and with the state of knowledge in geotechnical and structural engineering, (b) review the field experience accumulated since their promulgation,

and (c) recommend potential modifications that could improve their effectiveness. As part of this effort, a field study was conducted of present

practice in excavation, trenching, and shoring and of the impact of the

OSHA regulations as perceived by contractors.

This research was performed to; (1) study field practices in excavation

bracing, particularly empirical practices that seem to be adequate and

generally accepted in the industry; (2) identify factors affecting safety

performance in trenching operations; and (3) solicit comments on how the

OSHA standards might be Improved. Data were gathered through personal

interviews, small group meetings, field observations and mailed-out

questionnaires. The Information was both general and technical in nature

and was provided primarily by utility contractors. The general information concerned company operations, management and safety practices, and

other facts about the contracting firms. The technical Information dealt

with criteria used by field personnel in evaluating safety conditions

and with protection practices used in trenching and excavation operations.

The technical data provided such information as soil conditions, water

conditions, design of bracing systems, determinations of the angle of

repose, use of subsurface explorations, causes of trench cave-ins, extent

of use of certain types of bracing systems, types of wood used, typical

trench configurations, and specific problems with the OSHA standards.

Data were collected from various geographical regions in the United States.

Results from the study show that contractors use various types of bracing

or support systems in trenches to cope with the variability of soil and

groundwater. While some contractors rely on engineering expertise,

others dig their own test holes or conduct some other type of subsurface

investigation in proposed areas of work to identify subsurface conditions.

In some Instances, the owners of the proposed work areas provide boring

logs which may be used by contractors. The study also showed that most

trenchwork is between 5 and 15 feet deep with the trench width usually

being about 3 feet.

Engineering judgment plays a large role in actual field decisions con- cerning necessary bracing systems for trenches when the trench walls

are not sloped. In general, most utility contractors do not consider

the OSHA standards helpful for determining the adequacy of trench

shoring systems. It was noted that when engineering expertise does

not exist in a company, the contractor generally resorts to the use of

empirical practices which have been time-tested for given soil types.

vlli
The type of protection provided for trench workers varies considerably

among utility contractors. The use of trench shields or trench boxes

Is quite popular In the Eastern States and In parts of the Midwest,

while hydraulic shores are often used In similar soil conditions In

the Southern and Western States. When wood bracing systems are used,

the type of wood could be hardwood or softwood, depending on the region

of the country. Other differences noted between various contractors'

practices are not directly based on geographical locale, but more on

the size of the contracting company. For example, large firms are usually employed for deep trenchwork and they will often use sheetplllng

as their support system.

The number of recorded Injuries was obtained from the respondents and

converted to an Injury frequency Index In order to characterize the

safety performance of the companies. However, uncertainties In the

Injury reporting practices of the various companies and In the representativeness of the samples prevented the drawing of firm conclusions

about the relation between safety performance and those factors believed

to have Important Influences.

Finally, this study obtained comments from contractors concerning the

current OSHA standards on trenching safety. The most often quoted

statements were that the standards are Impractical, antiquated, too

restrictive and not responsive to varying soil conditions. There

seems to be a strong opinion among contractors that OSHA should play

an advisory role In addition to Its policing function with respect to

trenching safety.

lx
ABSTRACT

Results of a field study of trenching practices, safety related problems

In trenching, and the effect of the Occupational Health and Safety

Administration (OSHA) regulations for excavation, trenching and shoring

are presented. The data were gathered from over 100 Interviews with

contractors and foremen In various regions of the country and from the answers to questionnaires sent by contractors ' associations to their

membership. The data Indicate: 1) the technical aspects of trenching

work, 2) the Industry's opinion of the current OSHA regulations, and

3) factors affecting safety performance In trenching work.

Key Words: Construction safety; construction standards; excavation;

safety regulations; shoring; trenching.

X
1.0

INTRODUCTION

1.1 GENERAL

The OSHA regulatlj^ns for excavation, trenching, and shoring were promul

gated In 1974. Field experience accumulated since their promulgation Indicated that the regulations were difficult to enforce because

of technical weakness and ambiguities. Consequently In June 1976 OSHA

engaged the National Bureau of Standards, NBS, to (a) study the compatl

blllty of the technical provisions In these regulations with actual

construction practice and with the state of knowledge In geotechnical

and structural engineering, (b) review the experience accumulated since

their promulgation and (c) recommend potential modifications that could

Improve their effectiveness.

This report presents the results of field studies of present practices

In excavation, trenching and shoring and of the Impact of the OSHA regu

latlons as perceived by contractors. Much of the Information presented

In this report Is not within the realm of OSHA’s responsibility for

regulations. However, the data Is presented to provide Information to

contractors In a consulting and advisory role.

1 .2 PURPOSE AND SCOPE

The purpose of the Investigation was: (1) to examine those factors

believed to have major Influences on safety performance; (2) to study

field practices In excavation bracing, particularly empirical practices

that seem to be adequate and generally accepted In the Industry; and

(3) to determine the Industry’s opinion of the current OSHA regulations

Part of the Information gathered In this Investigation was obtained

through discussions with contractors (mostly utility) Involved In

trenching and excavation operations, through written comments received

from such contractors, and through visual Inspections of job sites.

The Information was either general or technical In nature. The general

information concerned company operations, management and safety practices, and other characteristics of the contracting firms. The technical Information Included specific criteria used by field personnel In

evaluating safety conditions and protection practices employed In

trenching and excavation operations. Similar Information was also

obtained from letter surveys conducted by the National Utility Contractors Association and by the National Association of Plumbing, Heating,

and Cooling Contractors.

The results of the field Interviews are presented In Chapter 2 and 3;

the results of the letter surveys are given In Chapters 4 and 5; and th

Appendix contains details of the questionnaires and specific comments

made by contractors on various topics.

* Numbers In bracket refer to references listed at end of report.
Also presented, as Appendix G, is a report prepared by a Trenching Hazard

Task Force of the Building and Construction Trades Department, AFL-CIO,

which was appointed in conjunction with this project In order to Identify

the safety problems as viewed by workers who actually enter the trench.

The task force was composed of Individuals representing over 200 years of

total experience In trenching work. The report gives further Information

on the industry's view of acceptable practice In trenching work.

1.3 DEFINITIONS; EXCAVATION VS. TRENCH

It Is Important to understand the basic differences between the terms

"trench" and "excavation". By definition a trench Is a special type

of excavation. Although there Is no consensus on the exact difference

between a trench and an excavation, some general distinctions are accepted. A trench is considered to be a long, narrow excavation which

is left open for a relatively short period of time, usually less than

a day. The excavated material from a trench Is generally stored within

a few feet of the trench and placed into the excavation after the

desired work Is completed. Trenches tend to be excavated for the

installation of utilities such as sewer, water, electric, gas, and

telephone lines. In contrast, when contractors use the term "excavation,” they refer to an excavation that remains open for long periods of

time and where most of the excavated material Is usually not backfilled

Into the excavation. Excavations are common for such structures as bindings and bridge abutments where the structure Itself replaces the

material that was excavated. In summary, a trench differs from an excavation In that a trench Is long and narrow, uses the excavated material

as backfill, and tends to be open only for a short period of time.

Different concerns are Involved in the side support provisions for

excavations and trenches. Many excavations occur In the cities, and

the bracing systems are often designed by licensed professional engineers to provide assurance that the banks will be maintained and that

subsidence of adjacent properties, particularly those supporting buildings, will be minimized. Few such bracing systems have been known to

fall. On the other hand, the temporary nature of trenches and the

changing nature of soil conditions, make trenching operations different.

Trench shoring systems are rarely designed by licensed professional

engineers, and prior engineering design Is often impractical since soil

conditions may vary greatly over short distances requiring that

decisions be made In the field.

There is a clear distinction between those contractors Involved In

opening excavations and those Involved In opening trenches. Only In rare instances would a single contractor be Involved In both types of

operations, and such a contractor would generally run a larger, more

diversified operation. This distinction was evident when several

trenching and excavation sites In the Washington, D.C. area were

visited and Informal discussions held with several area contractors

at the start of the study.

2
Conclusions drawn from discussions with excavation and trenching

(utility) contractors revealed that this study should address primarily

safety In trenches rather than safety In excavations. Excavations are usually engineered, are machine-intensive and rarely have cave-ins.

On the other hand, trenches are rarely engineered, are more laborintensive, and frequently do cave In. Thus Injuries from caving banks

are more likely to occur In trenching operations than In excavations.

Although some excavation contractors were Involved in the field study,

more utility or trenching companies were Involved In the final investigation. Excerpts from a few of the conversations held with excavation

contractors are Included In the Appendix (Part C)

2.0 FIELD INTERVIEWS

2.1 METHODOLOGY

A set of questions was developed which could be used as a guide when

talking to the various contractors. The questions dealt with general

Information about the contractor, management philosophies, work practices that could affect worker safety, safety programs, type of work

performed, nature of soil conditions generally encountered, and the

current OSHA regulations on trenching operations. The final questionnaire Included about 100 questions.

Assistance In contacting utility contractors In different parts of the

country was obtained from the National Utility Contractors Association

(NUCA), which provided the names of local utility contractor associations throughout the country.

An evaluation was made to determine the most desirable locations for

this study. Soil type and shoring practices In specific locations were

primary considerations. In a few Instances, a strong willingness on the

part of the utility contractors to participate In the study was also a factor. Nine sites or municipal areas were eventually selected. These

Included Washington, D.C.; Boston, Mass.; Atlanta, Georgia; Pittsburgh,

Penn.; Kansas City, Mo.; Omaha, Neb.; San Francisco, Cal.; Houston,

Texas; and New Orleans, La.

The utility contractors' association In each selected area was contacted

and Informed about the study. In all cases, these associations volunteered to assist NBS In the study, and the utility contractors In each

location gave freely of their time to discuss their trenching operations. It Is noted that In some Instances time did not permit all

willing contractors to be interviewed.

Personal Interviews were arranged and scheduled by each participating

utility contractors' association. The persons Interviewed were familiar

with management practices and field operations of their companies. Some

companies sent several representatives. Participants Included vice

3
presidents, general managers, general superintendents and safety officers; however, In most Instances, the president or owner of the company

was Interviewed.

Interviews were scheduled to take about one hour; but most participants

became quite Interested In the topics being discussed, and, consequently,

additional time was taken to elaborate on various subjects covered during

the Interview. Although structured questions were posed, a flexible

approach was taken and comments on additional topics were also recorded.

To augment the Information gained In the Interviews and to obtain a clearer perspective of trenching practices, field visits were made to

different sites to observe the various types of current trenching

operations.

2.1.1 Data Coding

After the Interviews had been completed, codes were set up for each

question In the questionnaire. The codes represented general categories (in some cases, specific categories) Into which the responses could

be grouped. In order to minimize the Introduction of bias, coding was performed by technicians and Injury frequency was calculated after the

other coding had been completed.

Injury frequency was determined by asking the person being Interviewed

the number of recordable Injuries Incurred and average number of workers

employed over a given time period. The Injury frequency index was

expressed as the number of recordable injuries per one million man-hours

of exposure. By using this Index, the safety performance of all companies could be compared In relative terms.

Injury frequencies were compared with different responses to various

questions. However, no firm conclusions should be drawn from the comparisons because: 1) It Is not possible to ascertain whether Identical

accident reporting practices exist among all respondents, 2) It was not

possible to characterize the nature or severity of the reported injuries,

and 3) It Is uncertain whether the .sample used can be considered statistically representative. Thus, conclusions regarding those factors believed

to have major Influences on safety performance In trenching work were not

formulated. Nevertheless, the average Injury frequency Indices associated

with various response are presented as Indications of general trends.

The correlations between the various factors and to Injury frequencies

were founded upon statistical analyses of the data. However, references

in the text to statistical tests Is held to a minimum to aid the reader.

A high degree of positive correlation Implies that as one variable Is

Increased, so does the Injury frequency.

Kendall's correlation test^^l was employed In the analysis of the data.

This is a nonparamet rlc test, which means that a normal or bell-shaped

distribution of the data Is not required. The distribution of the

Injury frequencies was not normal, therefore such a test was essential.

This need Is confirmed by the fact that the lowest Injury frequency

4 was
9, the highest Injury frequency was 371 and yet the mean was about 86

with a median of 67.

Data need not be normally distributed, because a nonparametric test

considers the relative ranking of variables and not their absolute

values. For example, the values of a particular variable for different

cases, say 2, 6, 12, 20 and 40, would be treated as relatively ranked

values of 1, 2, 3, 4 and 5. Thus, the mean of the values is not considered to be the absolute value of 16 but the ranking value of 3. Note

that the value, 16, would be the average but not the median point of

the first values, while 3 would be the mean and median value of the

ranked data. In Kendall's correlation, the relative ranking of values

are used in determining statistical significance. That is, for a particular case, the relative ranking of a variable is compared with the

relative rankings of the same variable with other cases. Comparisons

are made between the relative positions of these rankings. If a variable is positively correlated with another, it means that as the

relative ranks of one variable Increase, the relative ranks of the other

variable also Increase.

2.2 CHARACTERISTICS OF THE INDUSTRY

To give a clearer perspective of the type of contractors involved in

trenchwork, a brief description of the industry is provided. This

information will be helpful in interpreting and understanding comments

and conclusions to be made later in this report. Because many of the

contractors in the survey referred to themselves as utility contractors,

that title will be used in this report.

A utility contractor is essentially one who installs storm sewer lines,

sanitary sewer lines, water lines, telephone lines, electrical lines, or

gas lines. In general, the sewer and water line contractors are considered to be "true” utility contractors. They often specialize and orient

their operation to only one aspect of utility work. However during a slack period, some contractors shift into other areas; for instance, a water-line contractor may bid on shallow sewer lines.

Most projects are associated with public works, while a small percentage

are private sector jobs involving principally development projects, such

as subdivisions. As a consequence, almost all the work contracts of

utility contractors are obtained through competitive bidding.

Most contractors tend to be small in terms of their annual dollar volume

(Table 1).* A majority of the contractors do less than $4 million of

work annually, and perhaps only about 15 percent of the contractors have

an annual volume greater than $10 million. These larger companies would

* The information in Table 1 and in all subsequent tables in the chapter

was obtained from this field study.
generally be those in which the utility work constituted a branch or division within the company; so, the actual trench volume would still

remain fairly small.

Table 1: Annual Dollar Volume of Utility Contractors

Annual Dollar Volume No. of Companies Percent of Total

Less than $1 million 11 12.2

1-2 22 24.5

2-3 11 12.2

3-4 6 6.7

4-5 7 7.8

5-7 10 11.1

8-12 12 13.3

12-30 8 8.9

Over $30 million 3 3.3

90 100.0*

* The total value of the sum of all valid responses will always be

reported as being 100% in this report. To guarantee this sum it may

be necessary, through numerical rounding, to deviate slightly from

standard rounding conventions. Examples: 22 of 90 total responses

is 24.44% of the total, but this was rounded to 24.5% to obtain the

necessary total of 100.0%.

Table 2: Percent of Company Volume of Work That Is Trenching

Percent that is

Trenchwork

0-25

26-50

51-75

76-90

Over 90

No. of Companies

14

11

10

15

35

85

Percent of Total

16.5

12.9

11.8

17.6

41.2

100.0

6
Table 3: Amount of Company Work Done Within 50 Miles

of the Home Office*

Percent of Company Volume No. of Companies Percent of Total

0-25 5 5.5

25-50 8 8.9

50-75 7 7.8

75-90 15 16.7

over 90 55 61.1

90 100.0

* 1 mile = 1.61 kilometer

Table A: Average Number of Field Employees In the Company

No. of Workers No. of Companies Percent of Total

10 or less 1

' 1 1.1

10-25 21 23.6

25-50 25 28.1

50-75 7 7.9

75-100 11 12.4

100-200 14 15.7 over 200 10 11.2

89 100.0

7
Utility contractors do virtually all the work associated with their contracts, and this demonstrates that many contractors have diversified

capabilities, such as blasting and paving, which support the trenching

operations. As most contractors do primarily trenchwork (Table 2), they

bid on jobs in the general vicinity (within 50 miles) of the home office

(Table 3). This practice is probably caused by the following factors:

(1) the contractor may own his equipment and transporting it any greater

distance would be too costly to be competitive; (2) the contractor would

have a better understanding of soil conditions near "home” and would be

reluctant to work areas having unknown soil conditions; (3) the contractor generally keeps a constant crew and this may not be possible if he

were to move too far from the home office; and (4) the contractor would

lose control of his job if it were too far to monitor on a regular

basis

.

The work force Is small because the annual volume is generally small.

The majority of the contractors tend to have less than five trenching

crews working for them (Table 4). The average size of a crew is from

five to eight people, but may vary considerably because of different

soil conditions. A typical crew may have a foreman for supervision,

a backhoe operator to dig the trench, a bulldozer operator to backfill

the trench, two workers in the trench making the connections, and two

workers supplying materials to those in the trench. Less men are needed if the foreman operates the backhoe or if the materials are

light In weight and can be handled by one worker. Considerably more men would be required if shoring were required in the trench, or if

the materials were large and unwieldy.

The home office staff of a typical utility contractor is also quite

small, rarely more than 10 people (Table 5). These individuals often

have extensive field responsibilities In addition tp their "in-house"

duties. They are Involved In such tasks as accounting and payroll,

bidding, making field Inspections, monitoring jobs from the office

and general trouble-shooting tasks.

Table 5: Number of Home Office Employees

No. of Employees

1 or less

2

3

4

5 6-9

10-15

60

No. of Companies

24

6

6

5

75

1 36

Percent of Total

5.5

11.1

16.7

16.7

13.9

19.4

13.9

2.8

100.0

8
In the states with right-to-work laws, the utility contractors are not

unionized. In the other states, however, the contractors may work

either union or open shop. In either case, contractors tend to keep the same crew members. Most contractors’ work forces are such that over 75

percent of the workers have been with the company for longer than one year. This would not be true In a very busy season when a contractor

might add additional crews to his work force.

Because members of the work force are long-term employees, and since

very little subcontracting (or Interfacing activities with other trades)

Is done, trenchwork becomes routine. Consequently, by working together

the workmen become well-acquainted with their roles and the roles of

their co-workers.

In general, the trenching operation Is also routine. The backhoe opens

a length of trench, shoring Is Installed (optional), the pipe joint Is

made and more trench Is opened, and so on. As the piping operation

continues, a bulldozer backfills the trench above the pipe. Although

this phase of the operation Is routine. It Is the time when the profit

Is made. Nothing Is fixed because the operation Is so mobile. A job

site warehouse Is not practical; consequently, when machinery breaks

down or particular problems develop, the field personnel frequently

are not able to solve the problem. For this reason, management

usually maintains close surveillance on these jobs either by job

visits or through radio communications. The fact that the operation Is

constantly moving separates trenching operations from other work In the

construction Industry.

Job control for utility contractors seems to be different than for

general contractors. There Is little long-range planning In trenchwork,

other than determining, to some degree, the type of soil to be encountered on the job. Before the bid Is actually submitted, establishing

the type of soil Is necessary. After the job Is awarded, the contractor

makes arrangements for two or three pieces of equipment, the piping

materials (largely worked out by the pipe supplier), and the six-man

crew. Job control Is frequently on a dally basis (Table 6). Job control Is very Important and for this reason company owners or presidents

remain actively Involved In field operations. A minor Incident, such as

a broken hydraulic line, can be costly If the entire trenching operation

Is stopped, so management must be responsive to sudden unexpected job

needs

9
Table 6: How Often the Company President Visits the Jobs

Frequency of Visits No . of Companies Percent of Total

Dal ly 32 38.1

3 times a week 10 11.9

2 times a week 7 1 8.3

1 time a week 14 I 16.7

2 times a month 7 8.3

1 time a month 5 6.0

less than monthly 9 10.7

84 100.0

Although a utility contractor may do $3 million of work annually, this

amount should not be compared to similar amounts In general construction. This type of work Is very machine-, materials-, and labororiented. The machinery (bulldozers and backhoes) Is often large and

expensive. In addition, the pipe can be very expensive. The labor that

installs the pipe may be a fairly Inexpensive Item In a relative sense,

but this is where the contractor makes a profit. Very little subcontracting Is done. A single crew of perhaps six or seven men could do

$1 million of work In one year.

The foregoing description of utility contracting firms should be

considered when: (a) evaluating the comments made by the different

contractors, (b) trying to understand the findings and (c) making final

conclusions

.

2 . 3 TECHNICAL ASPECTS OF TRENCHING

As part of the field Investigation, considerable Information was obtained concerning the technical aspects of trenching operations.

These data were not obtained for specific analysis, but rather as general Information In the overall research effort. They are presented to document the available Information with a minimal amount of

discussion.

2.3.1 Trench Dimensions

Information was obtained on the geometry of typical trenches and Is

presented In Tables 7, 8 and 9. Utility contractors generally open

trenches which are deeper than 5 feet, thus requiring either shoring

or adequate sloping to assure worker protection from collapse. Trench

widths are usually narrow (less than 6 feet) but extremely wide trenches

were also noted. Trenches tend to remain fairly short (less than 50

feet), and the backfilling operation usually occurs shortly after the

pipe laying phase. Only for long water lines, operations requiring

shoring, or where large diameter pipes were being Installed, were longer

open trenches noted.

10
Table 7: Typical Trench Depth

Depth of Trench No. of Companies Percent of Total

less than 5 feet* 3 3.4

5-10 feet 34 38.6

10-15 feet 21 23.9

15-25 feet 21 23.9 over 25 feet 9 10.2

88 100.0

* 1 foot = 0.305 meter

Table 8; Typical Trench Width

Width of Trench No. of Companies Percent of Total

less than 3 feet 42 48.8

3-6 feet 17 19.8

6-9 feet 10 11.6

9-12 feet 3 3.5 over 12 feet 14 16.3

86 100.0

Table 9: Length of Open Trench Behind the Backhoe

Length of Open Trench No. of Companies Percent of Total

less than 20 feet 9 16.4

20-30 feet 12 21.8

30-50 feet 13 23.6

50-75 feet 8 14.6

75-100 feet 6 10.9

100-200 feet 2 3 .6 over 200 feet 5 9.1

55 100.0

2.3.2 Construction Practices

The contractors were asked questions to elicit Information on field

practices. So that the reader may know the scope of the available

Information, the questions are listed below but tabulations of the

responses are presented In Appendix A:

11
1) What is the most commonly found soil in the area?

2) How do you determine the angle of repose?

3) Is the OSHA table (P-1) helpful in this (determining the angle of

repose)

?

4) \-Jhat type of (solid) sheeting is used?

5) If you have skeleton (skip) shoring in a trench, what type do you

use most often?

6) Do you buy the (trench) boxes or do you build your own?

7) Is the shoring (timber) removed when the trench is backfilled?

8) What kind of wood do you use?

9) How often is it (wood shoring) reused?

10) How do you decide when lumber cannot be used?

11) Of the cave-ins you have seen, what do you think is generally the

cause?

12) \4hat is the worst soil or water condition that you run into in

your work?

13) Do you do your own soils investigations?

14) Do you have an engineer in your company?

15) Does the company ever hire soils consultants?

16) Does the company ever hire a consultant to design the (shoring)

bracing?

17) What dewatering method do you usually use?

No attempt will be made to formulate detailed conclusions from the

responses to the above questions, only a brief summary is presented.

Past experience and "rules of thumb" are being used more than the OSHA

regulations for estimating the angle of repose. Contractors make

efforts to investigate soil conditions, but one-third of cave-ins are

blamed on improper soil evaluations. A majority of contractors have

engineers In the company and very seldom are outside consultants

employed for bracing design.

3.0 FACTORS INFLUENCING SAFETY PERFORMANCE

Injury frequencies associated with the contractor responses were compared

to see If certain practices affected safety performance. The reader is
cautioned against drawing firm conclusions from these comparisons because

of the limitations mentioned in 2.1.1.

3.1 COMPANY SIZE

The relationship between company size and injury frequency is shown

below

Question 18: What is the annual dollar volume of the company?

Response Number of Companies Avg. Injury Frequency

Less than $4 million 50 71

Greater than $4 million 40 105

Because it is difficult to rationally attribute the frequency of Injuries

to the volume of work being performed, a closer analysis will be made to

define other variables which may affect frequency of injuries and which

are related in some manner to the annual dollar volume of work.

3.1.1 The Nature of Large Companies

Larger companies have more workers. To increase its volume of business

a company needs a corresponding Increase in the number of workers

required to perform the additional work. Large companies have more

crews. The type of work performed by each company, however, could

result in different numbers of crews for comparable volumes of work.

Labor-intensive trenching work (shoring) would require more workers than an equipment-intensive trenching operation (sloping), although the

actual contract amounts could be quite similar.

In short, the crew sizes may vary somewhat, but in the survey the actual

number of crews was related to the volume of work done by the company.

Large companies have more levels of management. Interview respondents

were asked specifically about the number of levels of management between

the workers and the company president. The range of responses was from

0 (in which the president assumed foreman responsibilities over the

crew) to 5 levels of management. The number of levels of management

increased as the volume of business increased.

Large companies do work in other areas besides trenchwork. Of the

contractors included in the study, 71% stated that over 50% of their

work was trenching. Some contractors were Involved in such nontrenching

operations as paving, building construction and excavation. Of the con- tractors surveyed, 34% stated that all of their work was trenching.

13
Large companies do a smaller portion of their work locally (near the

home office). A criterion for establishing what constituted "local"

work was work within a 50—mlle radius of the home office, a distance

that still permits close surveillance of jobs from the home office. Of

the contractors surveyed, 58% stated that their work was done locally.

Only 9% stated that less than 50% of their work was done locally.

3.1.2 Other Characteristics Affecting Safety

The foregoing discussion has dealt with factors closely related to the

annual dollar volume of companies. These factors have been of a quantitative nature in that most could be easily established by some objective

measure. The following discussion relates Other variables to the size

of the company, but these variables will be qualitative in nature.

Although only 8% of the companies surveyed had any major "people problems", the large companies reported more of these problems in their

firms. "People problems" would include such things as lack of qualified

workmen, or having people not willing to work.

Each person Interviewed was asked who was responsible for checking field

operations and how often the person responsible for such checks visited

a typical job. In the large companies, the Individual responsible for

checking on field operations is rarely the president or owner. The relationship between injury frequency and the person responsible for checking

field operations is presented below;

Question 19: Who in the home office is responsible for checking field

operations?

Response N* Avg. Injury Frequency

President or owner 44 74

All others; vice president 47 97

estimator, superintendent,

safety officer, etc.

Level of significance of the

difference between the two

categories: p < .001**

* N = Number of respondents.

** The significance of the differences between groups is based on the

Wllcoxon-Mann-Whitney test.t^’ The value of p indicates the level

of significance of the statistical finding; i.e., it shows the

possibility error in the conclusion based on the data examined.

If p < .001, there is less than one chance in a thousand that

the conclusion is Incorrect.

Tzr
3.2 MANAGEMENT PRACTICE

3.2.1 Impact of Management Style

A set of questions were asked to develop information on the types of

relationships maintained between top management and field workers.

These questions posed hypothetical situations and the contractors were

asked how they would handle them.

The views expressed concerning management styles are not to be construed

as being particular causes of accidents or remedies for improving safety

performance. Instead, they should be regarded as a reflection of a more general attitude maintained by top management concerning the field

workers. The results concerning management practices and attitudes will

first be presented individually and then discussed in a more generic

sense

.

Contractors were asked about their company policies on hiring and firing

of employees, specifically, the degree of control that the foremen held

over such matters. The responses could show the extent of top management Involvement in such circumstances. The questions, responses, and

injury frequencies were as follows:

Question 20: "Do the foremen hire their own men?”

Average Injury

Response N Frequency

NO, top management is involved to a degree, 49 71 or they can only suggest names of people to

be hired.

YES (full hiring authority)

Level of significance of the difference 41 105

between the two two categories: p< .01

15
Question 21: "Do the foremen fire their own men?"

Average Injury

Response N Frequency

NO, top management may intercede in the

process, or they may only initiate the

firing of workers

32 69

YES, or top management may fire the workers

too (full firing authority).

56 99

Level of significance of the difference

between the two categories: p< .01

Another indication of top management involvement at the worker level was obtained by asking each contractor how job conflicts were handled.

Specifically, they were asked what they would do if a worker were to come to them with a complaint about a foreman. The responses were as follows

:

Question 22 (rephrased): What would you do if a

a complaint about his

worker

foreman? came to you with

Response N

Average Injury

Frequency

Shift the worker to another crew, get the

two men together, listen to both sides, or study the situation carefully.

57 79

Back the foreman’s position 22 99

Level of significance of the difference

between the two categories: p < .02

The responses were grouped into two categories. The first category

represented top management involvement, even personal concern, in the

job conflict. These managers offered various means by which they would

handle the problem: shift the worker to another crew, particularly if

the conflict was one of personalities; get the two men (foreman and

worker) together and force them to establish a common solution; listen

to both sides to determine an acceptable solution; or study the situation to see how best to remedy the problem. In all of the foregoing

Instances, top management would take the complaint seriously, become

personally Involved in the job conflict, and actively seek a workable
solution. The second category representd top managers who would refuse

to become involved in such conflicts. They would back the position of

the foreman and Insist that the worker would have to work the problem

out with the foreman. In this case, the worker would have no recourse

if the complaint were legitimate and serious.

Another question concerning job conflicts was that of a new foreman who

was having difficulty in his job assignment. The managers were asked

how they would deal with such a situation, and the responses were as follows

Question 23: "Suppose you have a man who has worked for you for awhile.

You elevate him to foreman on some complicated work, but

he doesn’t seem to be able to handle dt. What would you

do?"

Average Injury

No Frequency

42 69

43 99

Response

Work with him until he catches on, shift

him to another crew, or work him into the

position slowly.

Make the new position a trial promotion,

put him back as a worker, or dismiss him.

3.2.2 Cost Information

Typically, utility contractors have projects or job sites under the sole

field supervision of the foreman. The foreman will generally have from

4 to 12 workers in the work crew, depending on the type of trenchwork

being done. The foreman is responsible for the entire field operation

and will report to someone in upper management such as the general

superintendent, vice president, or even the company president (or

owner). Although most firms will function in this manner, various

degrees of authority are given to the foreman. One area of interest is

the management policy concerning the sharing of cost information with

the foremen. Policies range from giving the foreman no cost information

to providing him with all available cost information. Since these policies could have differing influences on the foremen, particularly in

terras of management- imposed job pressures, the responses to the following question were compared with the Incurred injury frequencies:

17
Question 24: "What kind of cost information do you give to the

foremen?

Average Injury

Response N Frequency

None is given to them or mation is provided.

only general infor- 62 80

Give them detailed cost estimates, give them 28 102

reduced estimates, Informed only of overruns,

given complete access to cost records, or

they are told that their costs will affect

their bonus.

Level of significance of the difference

between the two categories: p < .04

3.2.3 Safety Practices

Contractors were asked questions about their company's efforts to maintain safety practices in the field and about the factors affecting job

safety. These questions concern safety meetings, safety representatives, insurance assistance or safety, OSHA, and other specific programs

or philosophies which exist in each company. The questions are presented below and the responses are found in Appendix B:

25. Are

26. How

27. Day

00 Who

29. Who

30. How

31 . Do t

32. Who

33. How

34. Is h

35. What

18
36. To what extent is the company president involved in job safety?

37. Who, outside the company, gives the most valuable assistance on job

safety?

38. What assistance do you get from the insurance company on job safety?

39. How often do they (insurance inspectors) visit jobs?

40. How valuable are insurance inspections?

41. What is the experience modification rating of the company?

42. How many OSHA inspections have occurred in the company?

43. (Of those firms inspected) How many citations were received?

44. How has OSHA affected your work?

45. Would you comment on your thoughts or experiences with OSHA

inspectors?

46. Has your accident history changed since OSHA became effective?

47. Do you get some kind of cost history that tells you how much each

injury claim amounts to?

48. Are safety records considered when establishing raises?

49. Is there a company safety incentive program?

50. How does the field know that the company fully supports job safety?

51. Would you say that some injuries are just part of the job?

Based on the responses to the above questions, the following observations are noted:

1. A large majority of the companies regularly hold "tool

box" meetings, but feelings are split concerning their

worth.

2. Top management is generally actively Involved in company

safety programs.

3. Insurance companies provide valuable assistance on matters

of safety.

4. OSHA has had a negative impact on company operations and

a majority of companies felt negatively towards OSHA

inspectors.

19
5. Few companies have safety incentive programs.

3.3 TYPE OF TRENCH PROTECTION

The type of protection for workers in trenches (sloping, trench boxes,

skeleton shoring or solid sheeting) influences to some degree the number

of injuries incurred. Each contractor was asked to estimate how frequently (in percent) each different method was employed by his firm.

The results showed that the frequency with which the different methods

were employed had varying effects on the frequency of injuries experienced by the company.

The most frequently used method of providing protection from trench

cave- ins was sloping the banks. Forty-four percent of the companies

used the sloping method on at least 50% of their trenches (12% used

sloping in over 90% of their trenches). Only 10% of the respondents

used sloping less than 10% of the time.

Question 52: What percent of your trenches are not braced but sloped?

Response No. of Companies Avg. Injury Frequency

0

- 59% 49 98

60- 100% 37 66

Level of significance of

the difference between the

two categories: p < 0.16

Shallow trenches (generally less than 5 feet deep) do not require shoring

and could be regarded as being sloped even if the trench walls were vertical. Thus, some companies involved in primarily installing water lines

would do almost all "sloping" as no further protection would be required

in shallow trenches; while other companies may actually be sloping trenches which are 10 to 12 feet deep. Failure to distinguish between these

two types of firms in the data presented difficulties in interpreting

the results.

A popular method of trench protection among some contractors was the use

of trench boxes or trench shields. Sixteen percent of the contractors

stated that they used trench boxes more than 50% of the time. Seventytwo percent said that they used trench boxes no more than 25% of the

time (33% never used trench boxes).

20
Question 53: Hov; often do you use a trench box?

Response No. of Companies Avg. Injury Frequency

0 - 24% 56 93

25 - 100% 25 70

Level of significance of

the difference between the

two categories: p

< 0.05

Another frequently used method of shoring was skeleton or skip shoring.

This type of shoring refers primarily to the use of hydraulic aluminum

shores (only a very small amount of this type of shoring Involved wood

bracing). Nineteen percent of the contractors stated that they used this

method more than 50% of the time, and 64% of the contractors said they

used skeleton shoring no more than 25% of the time (21% never used this

method)

.

Question 54 (rephrased): How often is skeleton or skip shoring used?

Response No. of Companies Avg. Injury Frequency

0 - 24% 42 85

25 - 100% 29 94

Level of significance of

the difference between the

two categories: p

< 0.08

The least used protection method was solid sheeting or tight shoring.

Ninety five percent of the contractors used solid sheeting or tight

shoring less than 25% of the time (38% never used this method).

21
Question 55:

Response

0 - 24%

25 - 100%

What percent of them (braced trenches) get solid sheeting?

No. of Companies Avg. Injury Frequency

67

9

80

142

Level of significance of

the difference between the

two categories: p < 0.02

It should be emphasized that the relations between injury frequencies and

shoring methods do not indicate that certain methods are not to be used.

It shows that when some methods are used, injuries can be expected to

increase. Clearly, the method employed is dictated more by the soil

conditions encountered than by personal preference for a shoring method.

The results did not make comparisons of the Injury frequencies associated

with one shoring method to those associated with another shoring method.

As a partial explanation of these findings, consider the protection methods (trench boxes, skeleton shoring, solid sheeting) merely on the basis

of materials handling. Skeleton shoring and solid sheeting require a great deal of materials handling other than the pipe being laid. It is

perhaps the handling of the shoring materials that increases the number

of job injuries. Several contractors commented that in handling wood

shoring, workers frequently got splinters in thfeir hands and often dropped

lumber on their toes. In installing skeleton shoring, primarily done

with hydraulic shores, the injury most commonly encountered was that

workers pinched their fingers in the collapsible shores when installing

or removing them. Another explanation can also be offered: since

installing skeleton shoring or tight sheeting requires more materials

handling, a larger crew is required to perform the work. Other studies

[

’ J have shown that smaller crews tend to be "safer."

In summary, projects using the skeleton shoring method or the tight sheeting method would be expected to have more injuries because of an increase

in materials handling.

4.0 NATIONAL UTILITY CONTRACTORS OF AMERICA (NUCA) SURVEY

In January 1977, the National Utility Contractors Association (NUCA)

sent out about 2,000 questionnaires entitled, "Questionnaire for Contractors Who Do Work Which Involves Trenching." Responses were received

from 223 contractors from more than 40 states, including some national

and International contractors. Respondents were primarily utility contractors, although several general contractors also responded. More

than half of the forms were completed by company presidents and owners.

Most of the remaining responses were completed by Individuals who were

22
in uppermanagement positions. About 70% of the responses came from

locations east of the Mississippi River, particularly from the Northeastern States where the NUCA membership is strongest. Although nonmembers were also sent a questionnaire (contractors on the NUCA mailing

list), participation from such contractors did not appear to be very

high.

This chapter presents the results of the responses to the NUCA questionnaire (a sample of which may be found in Appendix E). Much of the

information gathered from the NUCA study was similar to that from the

NBS study reported in previous chapters. The questions were designed

to gather information on the following subjects: characteristics of the

business, technical aspects of trenching. Impact of OSHA, and company

safety programs.

4.1 CHARACTERISTICS OF COMPANIES RESPONDING TO THE NUCA SURVEY

Responses to the NUCA questionnaires indicated that generally the companies which do trenching are relatively small, with a typical company

doing an annual business of about $2 million (Table 10). A typical company would employ about 30 field workers with the employment varying,

due to the seasonal nature of the work, from a low of about 16 employees

to a high of about 50. The field workers in such a company would accrue

about 51,000 manhours in a single year.

Although the utility contractors tend to be relatively small, the range

in size is quite large. The smaller firms responding to the questionnaire had a minimum annual dollar volume of $150,000 while the larger

firms did well over a billion dollars of work each year. More than

half of the respondents, however, had a volume of business that was less

than $3 million with 5% being over $30 million.

Table 10: Annual Dollar Volume of Utility Contractors

Annual Dollar Volume No. of Companies Percent of Total

than $1 million 41 19.1

1-2 55 25.6

2-3 29 13.5

3-4 22 10.2

4-5 20 9.3

5-7 18 8.4

7-12 14 6.5

12-30 5 2.3

$30 million 11 5.1

215 100.0

Although firms doing trenching work are referred to as utility contractors in this report, it is recognized that other types of contractors

(such as general contractors) also do trenching work. In general.

23
however, utility contractors tend to specialize in trenching work.

Seventv~four percent of the respondents stated that the majority of their

annual volume of work Involved trenching, and 37% stated that over 90%

of their work was in trenching (Table 11).

Table 11: Percent of Company Volume of Work That is Trenching

Percent that is Trenchwork No. of Companies Percent of Total

0-25% 33 14.8

26-50% 24 10.8

51-75% 44 19.7

76-90% 39 17.5 over 90% 83 37.2

223 100.0

Not only do these contractors specialize in trench work, but their work

is concentrated in a fairly small geographic region. i .e. , many of the

contractors did a majority of their work within a 25--mile radius of

their home office (Table 12). Reasons why a utility contractor would

prefer staying in a fairly localized area were presented in Section 2.2.

Table 12: Amount of Company Work Done Within 25 Miles of the

Home Office

Percent of Company Volume No. of Companies Percent of Total

0-25% 58 26.2

25-50% 62 28.1

50-75% 34 15.4

75-100% 67 30.3

221 100.0

Utility contractors are involved in such trenching operations as the

Installation of water lines, sanitary sewers, storm sewers, gas lines,

electric lines, and telephone cables. Contractors may specialize in

particular trenching operations, but few limit their work to that

extent. Only 12% of the contractors indicated that they perform only

one type of installation. Although various combinations of work were

noted, typical combinations for a single contractor were: storm and

sanitary sewers; storm sewers, sanitary sewers and water lines; sanitary sewers and water lines. Other frequently occurring combinations

with water line Installations were Installation of gas, telephone, and

electric lines. Most utility work, however. Involves sewer installations and water line installations.

Most of the work performed by utility contractors is awarded through

public works contracts and is obtained through competitive bidding.

2A
For example, 70% of the contractors received at least 90% of their work

through competitive bidding. Only 7% of the contractors received less

than 50% of their contracts through competitive bids; such contractors

apparently negotiate most of their work with private development firms

on projects such as subdivisions. There was a strong positive correlation between the amount of trenchwork performed by the contractors and

the amount of work that was obtained by competitive bidding (p < .001);

this is an indication that the contractors who negotiated much of their

work were involved in other tasks such as those pursued by general con- tractors. Of course, utility work done in subdivision developments

(private work) might be obtained through competitive bids or by

negotiations.

Companies reported average employment of 4 employees to more than 20,000

employees (Table 13). The very large contractors had many employees,

but they were also more diversified in the type of work they did. The

large contractors had trenching as a smaller percentage of their annual

volume of business than did the small contractors, apparently the large

companies were general contractors.

Table 13: Average Number of Field Employees in the Company

No. of Workers No. of Companies Percent of Total

10 or less 32 19.1

10-25 46 27.4

25-50 40 23.8

50-75 14 8.3

75-100 11 6.6

100-200 14 8.3 over 200 11 6.5

168 100.0

There is a fairly equal distribution of union and open shop (merit shop)

contractors. Three percent of the contractors operated "double-breasted”

(both union and open shop). The larger companies generally ran union

operations although exceptions were noted.

In spite of the highly seasonal nature of the work involving trenching,

particularly in the Northern States, contractors maintain a fairly con- sistent composition in their work forces. For example, 68% of the con- tractors stated that over 60% of their field workers had been employed

in the company for over a year and 32% stated that 32% of the workers

had been with the company for more than five years. Although the work

is seasonal in some areas, with complete work stoppage occurring during

the winter months, the utility contractors apparently rehlre the same workers when work resumes in the spring.

Not only are utility contractors generally small in terms of the number

of field employees, but also in the number of home office employees.

25
About half of the contractors had a maximum of 3 employees in the home

office and 90% had no more than 15 home office employees (Table 14).

The home office employees, partlcuarly in the smaller firms, still have

direct responsibilities for the field operations, and consequently,

often spend a large portion of their time in the field.

Table 14: Number of Home Office Employees in the Company

No. of Employees No. of Companies Percent of Total

1 or less 29 13.3

2 32 14.7

3 44 20.2

4 27 12.3

5 20 9.2

6-10 30 13.8

11-15 16 7.3

16-99 10 4.6

100 and over 10 4.6

25

218 100.0

The small size of the utility contractors lends a degree of informality

to the overall operation; and because much of the work is within a 25-

mile radius of the home office, there is improved job control. This

work radius permits the managers to personally and closely watch the

jobs and be more responsive to field problems that arise. The degree of

contact between workers and management was indicated by the frequency of

visits by the company president to each job site (Table 15). Seventythree percent of the contractors stated that the company president

visited the jobs at least once a week.

Table 15: How Often the Company President Visits the Jobs

Frequency of Visits No. of Companies Percent of Total

Daily 80 36.4

3 times a week 38 17.3

2 times a week 43 19.5

2 times a month 22 10.0

Monthly 12 5.4

Less than Monthly 25 11.4

220 100.0

The size of the firms is also reflected in the degree of sophistication

of their engineering capability. The larger firms may have a staff of

engineers, but the small firms seldom do. Only 22% of the contractors

Indicated they had in-house engineers (registration not ascertained).
while 45% stated they had never hired an engineer, even for consultation.

The remaining firms stated specific instances in which the services of an engineer were obtained.

In summary, most utility contractors are small, although there is con- siderable variation in size; the operations of a single company tend to

be maintained in a fairly small area and in an informal manner; and most

are very specialized constructors, doing principally trench work.

4.2 TECHNICAL ASPECTS OF TRENCHING

This section summarizes the responses to those questions in the NUCA

study dealing with site conditions encountered during trenchwork, dimensions of trenches and frequency of use of different trench protection

methods

.

Trenching contractors must be concerned with protecting their workers

from trench-wall collapse, and many factors dictate which protection

method will be most economical and effective. Perhaps the most critical

factor is the unpredictable nature of the soil encountered. Although

specific information was obtained from more than 40 states, there is

little consistency as to which types of soil occur in any one area. The most commonly encountered soils are soft to medium clays, clayey

sands or sandy clays, and stiff clays. Approximately 10% of the con- tractors stated that all types of soils could be found in their working

area. Several contractors indicated that rock, sand and gravel, and

very hard clays were most frequently encountered.

In addition to the soil type, contractors were asked to describe the

moisture content of the soil as "wet" or "dry."* Twenty-four percent of

the contractors indicated that the soil was mostly wet, 30% stated that

the soil was mostly dry, and 46% indicated that both conditions existed

either in different regions or during different seasons. Only a few areas could be specifically identified as being principally wet or principally dry. Massachusetts tends to be principally wet with a predominance of stiff clays and clayey sands or sandy clays. Pennsylvania

tends to have dry conditions with stiff clays, very hard clays, and

rock. Washington and Orgeon have primarily sand and gravel and clayey

sands or sandy clays which tend to be wet. Even in these locales where

fairly consistent soil types were encountered exceptions were noted.

Contractors were also asked about the depth to the water table on most

of their jobs. Responses showed that 34% of the contractors encountered

the water table typically from 5 to 10 feet below the surface, 34%

encountered it from 10 to 15 feet below the ground surface and 25%

encountered it at depths greater than 15 feet (Table 16).

* Although differences can readily be expected, particularly due to

seasonal changes, some indication of moisture content was deemed

informative

.

27
Table 16: Typical Depth to Water Table

Depth of Water Table No. of Companies Percent of Total

0-5 feet 13 7.1

5-10 62 33.7

10-15 62 33.7

15-20 27 14.6 over 20 feet 20 10.9

184 100.0

The type of protection provided for the workers In trenches Is also

dependent on the trench configuration. Contractors were asked to

describe what they considered to be a typical trench (Table 17). Only

16% of the contractors stated that they generally dug trenches less than

5 feet deep, for which protection is not legally required. About threefourths of contractors reported typical trench depths between 5 and 15

feet and only 7% of the contractors tended to work In trenches over 15

feet deep. By combining the Information in Tables 16 and 17, It can be seen that subsurface water Is encountered in many of the trenches: 93%

of the contractors dig trenches less than 15 feet deep, and water Is

encountered at less than 15 feet by 75% of the contractors.

Table 17: Typical Trench Depth

Depth of Trench No. of Companies Percent of Total

1-5 feet 31 16.2

5-10 78 40.6

10-15 70 36.5

15-20 11 5.7 over 20 ft. 2 1.0

192 100.0

Contractors were also asked about the typical width of trenches at the

bottom of the excavation. Trenches were relatively narrow — 42% of the

contractors indicating that trenches generally were less than 3 feet

wide and another 51% Indicating that the widths were generally from 3

to 6 feet wide (Table 18).

28
Table 18: Typical Trench Width

Width of Trench No. of Companies Percent of Total

1-3 ft. 89 A2.4

3-6 106 50.5

6-9 8 3.8

9-12 5 2.4

over 12 feet 2 0.9

210 100.0

In response to the question on length of trench left open behind the

backhoe, 27% stated that the length was less than 25 feet, 33% stated

that It was from 25 to 50 feet, and 20% Indicated that It was from 50

to 100 feet (Table 19). Thus, 20% of the contractors have more than

100 feet of open trench behind the backhoe.

Table 19: Length of Open Trench Behind the Backhoe

Length of Open Trench No. of Companies Percent of Total

less than 25 feet 58 27.2

25-50 70 32.9

50-75 25 11.7

75-100 18 8.5

100-150 16 7.5

150-200 10 4.7

over 200 feet 16 7.5

213 100.0

Respondents were asked the type of protection they used In most trenches

based on dollar volume. To give a clearer Impression of the number of

times each system Is used, the data are presented as shown In Table 20.
Table 20: Frequency of Use of Sloping and Different

Shoring Systems

Percent of Use by Dollar Percent of Use by Dollar

Volume of Large Companies*

Type (under $13 million) (over $30 million)

Sloping 51 50

Trench Box 28 3

Skip Shoring

(Timber) 5 23

Tight Sheeting

(Timber) 3 5

Hydraulic Shoring 8 0

Screw Jacks 2 6

Steel Sheet Piling 3 13

100 100

No. of Companies = 203 No. of Companies = 11

* Companies having annual dollar volumes of from $13-$30 million were

not considered small or large contractors and since only 5 respondents were In this volume range, they were excluded from this tabulation. It should be pointed out that the firms with annual dollar

volumes of more than $30 million had trenching constituting 0-25%

of their total volume, consequently, these are only approximate

percentages.

It Is seen that sloping Is the most widely used trench protection technique; and It Is Interesting to note that trench boxes are the second

choice of the small companies, while for the large companies it Is

sklp-shorlng. It should be noted that a majority of the respondents

Indicated that they never used skip shoring, tight timber shoring,

hydraulic shoring, screw jacks, or steel sheet piling.

4.3 IMPACT OF OSHA , , { Contractors were asked to Indicate the usefulness of OSHA Tables P-1 and

P-2 (see Table 21). Only 3 percent Indicated that they were very helpful, while 20 percent Indicated they were a guide for the company, and

20 percent said they were too general to be helpful. Several of those

contractors using the tables as a guide remarked that they used them as such only to avoid OSHA fines. Fifty percent of the contractors Indicated that the tables were "not realistic for our work situations."

Some contractors made specific comments on such Items as problems with

existing burled utilities not being addressed. Inconsistent Interpretation of the standards, the standards not relating to specific conditions, standards not being a substitute for common sense, or that they

never saw the standards.

30
Table 21: OSHA Tables P-1 and P-2

TiibleP I

Note: Clays. Silts. Loams or Non-Homogenous Soils Require Shoring and Bracing. The Presence of Ground

Water Requires Special Treatment.

is

m o>

</5 2

2?O (Q i/U/i

I?

3f§ 8—

J

APPROXIMATE ANGLE OF REPOSE

FOR SLOPING OF SIDES OF EXCAVATIONS

Table P-2 TRENCH SH0RIN6- MINIMUM REQUIREMENTS

Siie and spacing of members

Depth of trenchKind or corKJition of earth

Uprights Stringers Cross braces

'

Minimum

dimenston Maximumspacing Minimumdimension Maximumspacing

Width of trench

Up to 3

feet

3 to 6

feet 6 to 9feet 9 to 12feet

12 to 15

feet

Vertical Horiiontal

Feel Inches Feet Inches Feet Inches IrKhes Inches Inches Inches Feet Feet

5 to 10 Hard, compact . .3»4of2x6 6 2x6 4x4 4x6 6x6 6x8 4 6

Likely to crack . . .3 > 4 or 2 X 6 3 4x6 4 2x6 4x4 4x6 6x6 6x8 4 6

Soft, sandy, or filled .

.

. .3 X 4 or 2 X 6

Close

sheeting 4x6 4 4x4 4x6 6x6 6x8 8x8 4 6

Hydrostatic pressure. . . .3 X 4 or 2 X 6

Close

sheeting 6x8 4 4x4 4x6 6x6 6x8 8x8 4 6

10 to IS Hard ..3x4or2x6 4 4x6 4 4x4 4x6 6x6 6x8 8x8 4 6

Likely to crack . . .3x4or2x6 2 4x6 4 4x4 4x6 6x6 6x8 8x8 6

Soft, sandy, or filled . 3x4or2x6

Close

sheeting 4x6 4 4x6 6x6 6x8 8x8 8x 10 4 6

Hydrostatic pressure 3x6

Close

sheeting 8x 10 4 4x6 6x6 6x8 8x8 8x 10 4 6

IS to 20 All kinds or cor>ditions 3x6

Close

sheeting 4x 12 4 4x 12 6x8 8x8 8x 10 10 X 10 4 6

Over 20 All kinds or conditions . 3x6

Close

sheeting 6x8 4 4x 12 8x8 8x 10 10 X 10 10 X 12 4 6

' Trench lacKs may be used m lieu of. or in combination with, cross braces Shoring IS not required m solid rock, hard shale, or hard slag Where desirable, steel sheet piling and bracing of equal strength may be substituted for wood.

31
The contractors were asked to recommend what changes should be made in

the OSHA standards. Of the 223 contractors, 36 made no comments.

Comments received were quite varied, but the most frequently mentioned

wore

8% - Need for the development of an understandable soil

classification system for easy contractor and OSHA interpretation.

11% - Need to change or permit leeway in the sloping requirements

(Table P-1).

12% - Rewrite Tables P-1 and P-2.

21% - Compliance officers should exercise more common sense,

be more job-oriented, and not be close-minded.

18% - Local conditions in the specific area should be the

determining factor (OSHA standards are too general).

30% - Varied comments including such topics as engineered excavations, hydraulic shores, and deletion of the standards.

Contractors were asked to provide information on their general impression of the OSHA compliance officers. Only 6 percent of the contractors

Indicated that "they really do identify safety hazards." Thirty-six

percent indicated that "they mean well but they don't understand con- struction work," 22 percent felt that "they Interpret the OSHA regulations to the letter of the law," and 5 percent felt that "they are just

out on the jobs to fine the contractor." Thirty percent of the contractors made specific comments about the compliance officers, describing

them as: having no common sense, having too little experience, trying

to justify their existence through contractor fines, being overly

"nlt-plcky," being unable to recommend better solutions to relieve the

conditions, and being totally unconcerned about safety but only wanting

to find faults by the letter of law. A few contractors had had no experience with OSHA and were unable to comment.

Several questions were asked about the experiences the contractors had

with OSHA inspections. Of the contractors who responded, 88 percent

indicated they had been visited by OSHA on at least one of their jobs.

The data showed that over half the contractors received more than 4

inspections. Further analysis of the OSHA inspections showed that 18

percent of the contractors had inspections which occurred after job

accidents, such as those which included job fatalities or multiple—party

injuries.

Contractors were asked how many OSHA visits resulted in citations.

Responses were as follows:

32
30% - received no citations

26% - received 1 citation

16% - received 2 citations

22% - received 3 to 9 citations

6% - received more than 10 citations.

On the average, contractors received 3.1 citations (median = 1.3) as the

result of OSHA Inspections. Since an average of 6.9 Inspections (median

= 3.1) occurred In each company, less than half the OSHA Inspections

actually resulted In citations.

OSHA fines associated with citations ranged from $7 to a maximum of

$18,000. Half the contractors received maximum fines of about $100,

while the average maximum fine was about $1,300. Five of the fines were

at least $10,000. Several contractors noted that when they contested

their fines, the fines actually paid were reduced In many Instances.

4 .4 SAFETY PROGRAMS

Contractors were asked about their specific efforts to Instill safety

awareness on their jobs. Seventy-eight percent of the contractors

stated they had job safety meetings or "tool box" ("tailgate") meetings

on their jobs. Of these contractors, 45 percent held these meetings

weekly, 9 percent held them on a biweekly basis, 22 percent held them

on a monthly basis, and 24 percent held them less frequently. Thus, 22

percent of the contractors did not conduct the tool box meetings, and

35 percent held them less frequently than biweekly (every 10 working

days) as often recommended.

The survey results Indicate that tool box meetings are conducted In a fairly nonstructured manner. Only 20% of the companies scheduled the

meetings for a particular day of the week. In addition, there was no well-established pattern as to who presides over these meetings, as shown by the following list of persons who conduct such meetings:

21% - foreman

20% - company president (or owner)

31% - job supervisor

7% - appointed safety representative

21% - various Individuals preside at different times.

When asked about company meetings (other than tool box meetings) dealing

with safety, 76 percent of the companies Indicated that they held such

meetings. When asked about safety Incentive programs, however, only 17

33
percent Indlcsted that such programs were maintained* The actual nature

of the safety Incentive awards and the persons who were eligible for

these awards varied with the different companies.

The contractors were asked about aspects of their safety programs

dealing with new workers, unsafe workers, and Injury responsibility.

With regard to new employees, the contractors were asked about the

safety orientation that such workers received. The results indicated

that 11% of the contractors provided no orientation, 72% provided an informal safety orientation and 17% had a formal orientation.

In response to a question about disciplining unsafe workers, 6 percent

of the contractors Indicated that workers had been fired for being

unsafe. In addition, the contractors were asked whom they held responsible in the event of an Injury. They responded as follows:

12% - placed the responsibility on the Injured worker

32% - placed the responsibility on the foreman

23% - placed the responsibility on the superintendent

33% - indicated that the specific conditions surrounding

each Incident would have to be known to properly place

the responsibility on one Individual.

Contractors were asked about the assistance they received from their

Insurance carriers. Forty-five percent of the respondents Indicated

that their carriers were "very helpful through their job inspections;"

18 percent indicated that they made Inspections "but they are not very

helpful;" 14 percent said that the Insurance carrier only sent brochures

and safety information; and 11 percent indicated that they became concerned only after accidents occurred. The remaining contractors (12

percent) Indicated other kinds of assistance, which varied from receiving direct aid in conducting safety meetings and seminars to receiving

no assistance at all.

In addition to their safety programs, the contractors were asked about

past safety performance, which was measured In several ways. First, the

contractors were asked about their Workmen’s Compensation Experience

Modification Rates, (l.e., the multiplier used to adjust the manual rate

on Workmen's Compensation Premium rates). These provide some Indication

of the frequency and severity of past Injuries. These ratings ranged

from a low of 0.48 (very good performance) to a high of 1.95, with an average of about 0.90.

Second, the contractors were asked how many OSHA recordable and losttime Injuries were Incurred during the past year. These Injuries were

compared with the manhours worked during the corresponding period of

time to provide a means of comparing the different contractors. The

incidence of lost-time Injuries was relatively low: 35% of the con- tractors had no lost time Injuries, 22% had one lost—time injury, and

34
12% had two lost-time Injuries. Consequently, injury frequencies

developed by using the lost-time data would be very sensitive to small

changes or minor errors in the number of lost-time injuries. The

recordable injuries, on the other hand occurred more frequently, as 67%

of the contractors had at least two recordable injuries. For this

reason, more reliable information was obtained by using the recordable

Injury data which represented more frequently occurring events, i.e.,

accidents. The injury data were used to develop an Injury frequency

index for each company which represented the number of recordable injuries that occurred in one million manhours of exposure. Recordable

injuries were a more viable statistical measure of safety performance

than the Experience Modification Rates since about a fourth of the

respondents did not provide Experience Modification Rate information.

4.5 FACTORS INFLUENCING SAFETY PERFORMANCE

After the NUCA data were coded, the injury frequency was determined for

each contractor that provided the necessary data (only 203 of them did).

The average Injury frequency index for all respondents was 90 (median

= 77).

The responses to the questionnaire that have been presented in previous

sections were evaluated to determine the relations between the different

variables and Injury frequencies. Standard statistical routines were used

to Individually correlate (Kendall’s Correlation) all of the variables

with the Injury frequency. This report presents findings which have

a statistical significance of at least 5 percent (denoted by p

< 0.05),

although in most cases the findings were much stronger (generally p < 0.001). A 5 percent level of significance means the chance that the data

represent a random occurrence is 5 percent, i.e., on the average 5 false

conclusions could be made in a hundred Instances where such a distribution of data exists. Appendix E contains a summary of the statistical

analyses. The reader is again cautioned against drawing firm conclusions

from these correlations for the reasons given in section 2.1.1.

Section 4.1 summarized the responses to those questions dealing with the

management characteristics of the companies Involved in trenching operations. When these variables were correlated with Injury frequency, it was found that the following factors were associated with an Increase in

Injury frequency index (p < 0.05):

1. Increase in the annual dollar volume of the company.

2. Increase in the number of field workers, home office

workers and man-hours worked in the company.

3. Decrease in the amount of work done within 25 miles of

the home office.

4. Decrease in the number of workers who visit the home

office.

35
5 . Decrease In the number of times the company president

visits job sites.

6. Decrease in the number of workers who have worked for the

company more than one year.

7. Decrease in the number of workers who have worked for the

company more than five years.

Information was obtained which dealt with how much of each firm’s work

volume involved trenching, from which the effect of company diversification on safety performance could be determined. It was found that

Injury frequency Increased as contractors did less trenchwork in

relation to their total volume (p < 0.03). Thus, it appears that

diversified contractors are more prone to job accidents than contractors specializing in trenchwork. A possible explanation could be that

while a diversified contractor may be experienced and knowledgeable in

various phases of work, the job control exercised in each area of work

is diminished.

Contractors were asked questions about the typical dimensions of their

trenches and the type of trench protection they used. The only variable

that showed some relationship (p < 0.04) to accident frequency was the

length of trench left open behind the backhoe. It is not clear why this

relationship exists.

Several questions were asked about the experiences the contractors had

with OSHA inspections. Results show that those contractors who had

more OSHA inspections following a job accident had the higher Injury

frequencies. Since inspections of this nature occur after fatalities

or after a multiple-party Injury, this result indicated that the more

severe accidents are associated with the higher accident frequencies.

Another finding showed that the firms with the higher Injury frequencies

had the higher OSHA fines levied against them. It might be expected

that the higher fines would be levied against those contractors who had

the more severe accidents, and certainly those contractors who had OSHA

inspections following job accidents probably had severe accidents.

5.0 NATIONAL ASSOCIATION OF PLUMBING, HEATING AND COOLING CONTRACTORS

(NAPHCC) SURVEY

In January 1977, the National Association of Plumbing, Heating, and

Cooling Contractors (NAPHCC) sent out questionnaires to 550 of its

members. These questionnaires contained 21 questions primarily con- cerning trenching operations, safety programs and the OSHA trenching

regulations. Ninety-four of the questionnaires were completed and

returned to the NAPHCC office; more than 30 states were represented by

the responses. The National Bureau of Standards was provided with a summary of the data (Appendix F), but the raw data were not made

available. About 50% of the responding contractors had less than 30

employees while about 20% had more than 500 employees. Correspondingly,

the annual dollar volume of business was less than $1.5 million for

36
tlons, contractors are fined for not obeying the regulations. The end

result Is animosity between contractors and OSHA rather than the desired

result, safety. The trenching standards must be revised so that they

enable safe trenching operations without undue economic penalties.

Further, It Is suggested that any standards which are written be periodically revised and Improved to accommodate the experiences of those

using the standards and to keep up with technology.

39
REFERENCES

[1] Department of Labor, Occupational Safety and Health Administration,

Construction Safety and Health Regulations, Part II, Subpart P,

Washington, D.C., June 1, 1974.

[2] Hollander, M. and Wolfe, D., "Nonparametrlc Statistical Methods,"

John Wiley and Sons, New York, 1973.

[3] Hinze, J., "Effect of Middle Management on Safety In Construction,"

Technical Report No. 209, Stanford University, 1976.

[4] Levitt, R., "Effect of Top Management on Safety In Construction,"

Technical Report No. 196, Stanford University, 1975.

40
about 50% of the contractors and 20% had more than $5.0 million. Six

contractors reported an annual volume of more than $10 million. The

respondents included nearly equal numbers of union and merit shops and

23 firms had double-breasted operations.

Most of the responding contractors were Involved in utility work including storm sewers, sanitary sewers, water lines, and gas lines. However,

for 80% of the firms, utility or trench work comprised less than 20% of

the annual dollar volume. In addition, 45% of the contractors stated

that they usually subcontracted the trenchwork.

In describing their particular trenching operation, about 90% of the

contractors indicated the trenches were generally less than 10 feet deep

and less than 3 feet wide. Over half the contractors slope (Instead of

brace) more than 90% of their trenches. The soil types encountered were

quite varied: "soft-medium clays were most common, followed by "all

types" and "sand and gravel". Half the contractors stated that ground

conditions were "dry" and the other half found "wet and dry" conditions.

Dry conditions tend to prevail since 69% of the contractors indicated

the water table was deeper than 10 feet and thus below the bottom of

most trenches. Most contractors never employed the services of a soils

engineer. Of those who had, such engineers were usually employed "only

before major bids" or "only when legal problems arose after the job

started."

With regard to safety, 81% of the contractors indicated they had safety

programs. Newly hired employees are generally (85%) given an Informal

safety orientation. Assistance from the Insurance carriers is rarely

(7%) in the form of job inspections, but rather (82%) in the form of

brochures and safety information sent to the company.

Concerning OSHA, 88% of the contractors had at least one OSHA inspection, and 79% had them at least once every two months. Thirty one percent reported receiving at least one fine that was associated with

a trenching violation such as insufficient sloping or inadequate shoring. When asked about the OSHA compliance officers, 10% stated "they

really do identify safety hazards;" 50% said "they mean well but they

do not understand construction work;" and 33% indicated" they Interpret

OSHA regulations to the letter of the law."

When asked about Tables P-1 and P-2 of the OSHA regulations, 9% of the

contractors felt they were "very helpful;" 48% said they were "a guide

for our company;" and 31% Indicated they were "not realistic for our work situations." These contractors were also asked to suggest specific

changes to the OSHA trenching standards. Several contractors suggested

that more "common sense" should be exercised in the enforcement of the

OSHA standards and that employees should be held responsible to a degree, particularly when they deliberately Ignore specific safety

instructions. Several comments concerned the individuality of specific

work sites: the standards should address their own work conditions more

directly, or at least have provisions to allow for clear interpretation

of the standards.

37
6.0 SUMMARY AND CONCLUSIONS

The purpose of this study was threefold: (1) to characterize the

trenching Industry, (2) to Identify factors affecting Injury frequencies, and (3) to determine the usefulness of the current OSHA standards

on trenching operations. Information was gathered through personal

Interviews and letter questionnaires.

Trenching work Is performed by companies of varying size, but most is

done by small firms specializing In this type of work. Most trenchwork

Is associated with the Installation of utilities, and trenches range

from shallow as for water lines to deep as for sanitary sewers. The

small utility contractors generally do their work within a 50 mile

radius of the home office. Large, diversified general contractors do

significant amounts of trenchwork, but only as a small part of their

total annual business. An Important characteristic of the small trenching firms Is the high degree of management-field worker Interaction.

Because of uncertainties In the data (as discussed in 2.1.1), firm conclusions were not formulated with respect to the effects of various factors on safety performance. The data, however, have been analyzed and

presented to reveal general trends.

In regard to the trenching Industry's opinion of the current OSHA standards on trenching operations, a large majority of contractors felt that

extensive revisions are needed. Appendix C lists specific recommendations for Improving various aspects of the standards. The following

revisions were often recommended:

1) develop an Improved soil classification system;

2) revise the shoring requirements so that work could proceed

within the trenches with less obstruction;

3) acceptance of engineered trench boxes and plywood sheeting

with hydraulic shores as alternate shoring systems;

4) revise the section dealing with escape provisions in the

event of a cave-ln so that practicality Is considered.

In general, the provisions should be revised and written with enough

flexibility to accommodate local conditions. Also, It was strongly

recommended that OSHA compliance officers have a technical background.

7.0 RECOMMKNDATIONS

Based on the results of this study. It Is recommended that the OSHA

regulations be revised In order to Improve their effectiveness.

The current OSHA regulations pertaining to safety In excavations have

been found to be Impractical and uneconomical for contractors to follow, and so they have been largely disregarded. Upon subsequent OSHA Inspec38
APPENDIX A

RESPONSES TO QUESTIONS RELATED TO FIELD PRACTICES

Question 1: What Is the most commonly found soil in the area?

Response No. of Companies Percent of Total

Various types noted 32 36

Clay 29 33

Clay and Shale 5 6

Loess 2 2

Clay and Sand 12 14

Hard Pan 4 4

Rock and Clay 4 4

Rock 1 1

89 100

Question 2: How do you determine the angle of repose?

Response No. of Companies Percent of Total

53

23

9

15

100

Other Responses

- strike the banks with a backhoe bucket and see the

angle with which the bank caves In. - see the angle that the banks

cave and slope a little more.

- let It slough until It Is

stable.

Rely on experience 42

(judgment)

Use some prescribed 18

constant slope

Whatever Is In compliance 7

with OSHA

Follow some set procedure: 12

79

41
Question 3: Is the OSHA table (P-1 ) helpful In this (determining the

angle of repose)?

Response No. of Companies Percent of Total

The table is used a lot 2 3

We use It only as a guide 14 18

It is of no help 60 79

76 100

Question 4: What type of (solid) sheeting Is used?

Response No. of Companies Percent of Total

None 25 29

Steel Sheet Piling 9 10

Tight Timber Sheeting 18 21

Steel Sheet Piling and Tight 28 33

Timber Sheeting

Solid plies and lagging, plywood

supported with screw jacks on hydraulic shores, or fiberglass

panels supported by hydraulic

shores

.

86 100

NOTE: Steel sheet piling Is used In trenches that are to remain open

for longer periods of time or when excessive ground water Is

encountered. Timber sheeting Is used on shallow trenches (from

8 to 14 or 16 feet deep) while steel sheet piling Is used In

deeper trenches.

42
Question. 5: Tf you have skelet on (skip) shoring In a trench,

what type do you use most often?

Response

None Is used shores* Hydraulic * Timber shoring

Screw jacks

Hydraulic shores, timber shoring

and screw jacks

Hydraulic shores and screw jacks

Hydraulic shores and timber

shoring

Timber shoring and screw jacks

No. of

Companies

15

44

4

6

2

8

6

2

Percent

of Total

17

51

5

72

9

7

2

87 100

* Twenty-three contractors (26%) mentioned that they used plywood on occasion In trenches. These plywood panels are generally supported

by hydraulic shores. Some panels would have stiffeners added for

additional resistance to bending.

Question 6; Do you buy the (trench) boxes or do you build your own?

Response

No. of Percent

Companies of Total

Company buys the trench boxes 21* 36

Company builds its own boxes 20 35

Company borrows or rents the boxes 7** 12

Company buys some and builds some of Its own 10 17

58 100

* Although many contractors bought their own trench boxes. It was

not uncommon for the contractor to make modifications on these

units. Modifications generally were made to strengthen the boxes

and to facilitate easier movement of the boxes In the trench.

** Contractors who borrowed or rented trench boxes were those who

did not use the trench boxes extensively In their operations.

43
Question 7: Is the shoring (timber) removed when the trench

Is backfilled?

Response

No. of

Companies

Percent

of Total

Mostly burled 18 42

Generally burled 2 5

Some burled; some left In place 4 9

Generally removed 7 16

Mostly removed 12 28

43 100

Question 8: What kind of wood do you use?

No. of Percent

Response Companies of Total

Hardwood* 41 71

Sof twood** 15 26

Softwood with some hardwood 2 3

58 100

* Hardwoods Included the use of primarily oak but some other types

was also noted (birch, gum, hickory, cottonwood, cypress, pecan).

** Softwoods Included the use of primarily fir but pine, spruce and

hemlock were also mentioned.
Question 9: How often is It (wood shoring) reused?

No. of Percent

Response Companies of Total

It Is not reused. It remains

buried In the trench

13 29

It Is rarely reused 4 9

We reclaim only the walers 3 7

We can get only a specified number

of uses (many reuses on the same

job when shoring Is used in leapfrog fashion, used as long as it

Is green and thus still strong,

reused but not for shoring, one reuse to 4 reuses, two jobs)

18 41

Reused quite often 6 14

44 100

Question 10: How do you decide when lumber cannot be used?

Response

No. of

Companies

Percent

of Total

Imperfections In the wood 2 4

Decaying and drying 14 31

Damages In usage 7 15

Damages In usage and decay 8 17

Depends on the extent of 3 7 usage (weakened In use)

It Is not reused 12 26

46 100

45
Question 11: Of the cave-ins you have seen, what do you think Is

generally the cause?

No. of Percent

Response Companies of Total

Poor supervision, failure to 5 7

recognize poor soil, too much

ditch left open, trench walls

exposed to the air too long

before bracing is Installed

Failure to shore. Inadequate 18 24

shoring, insufficient slope,

excessive overburden

Bad or unknown soil, excessive 24 32

ground water, poor evaluation

of soil conditions, clay with

silt layers (slick heads)

Ignorance 12 16

Breaks in waterlines and rain 6 8

Existing utility trenches 3 4

Vibrations of equipment and traffic 7 9

75 100

Question 12: What Is the worst soil or water condition that you

run into In your work?

Response

No. of

Companies

Percent

of Total

Running sand 46 53

Faults in clay 13 15

Gravel not cemented 5 6

Sand and clay faults 12 14

Excessive ground water 4 5

Other (mud on top of rock. 6 7 disturbed soil of previous

excavation, deep marine

clay, rocks, organic matter

and debris in soil) W 100

46
Question 13: Do you do your own soils Investigation?

Response

No. of

Companies

Percent

of Total

We know the area real well 1 1

We make test borings 8 10

We dig test pits or trenches 15 19

We may hire a testing lab 2 3

We make test borings at some 26 33

prescribed spacing

We rely on the owner's borings 9 12

We make a general field Investl- 5 6

gatlon

Our borings look only for rock 8 10

We make no investigations 5 6

79 100

NOTE: Many contractors stated that In certain areas they felt sufficiently confident about their knowledge of the soli conditions.

Therefore, no additional tests were necessary. Several contractors also stated that the owners' logs were used If they were

provided and appeared adequate. Contractor tests Included both

pre-bid and post-bid Investigations.

Question 14: Do you have an engineer In your company?

Response No. of Companies Percent of Total

Yes 49* 60

No 32 40

81 100

* Of these, 32 companies had registered engineers •

Question 15: Does the company ever hire soils consulants?

Response No. of Companies Percent of Total

Yes 49 54

No 42 46

91 100

47
Question 16: Does the company ever hire a (shoring) bracing?

consultant to design the

Response No. of Companies Percent of Total

Yes 7 12

No 52 88

59 100

Question 17; What dewatering method do you usually use?

Response No. of Companies Percent of Total

Sump pumps 25 29

Sump pumps and well

points 32 37

Sump pumps and deep

wells 14 16

Sump pumps, well

points, and deep

wells 16 18

87 100

NOTE: Contractors Indicated that dewatering was rarely subcontracted

to other firms.

48

i
APPENDIX B

RESPONSES TO QUESTION ON SAFETY PRACTICES AND ATTITUDES

Question 25: Are tool box meetings held on the jobs?

Response No. of Companies Percent of Total

Yes 79 89

No 10 11

89 100

Question 26: How often do you have them (tool box meetings)?

Response No. of Companies Percent of Total

Dally 7 9

Weekly 37 47

Two per month 9 11

One per month 12 15

Less than monthly 6 8

Unknown 8 10

79 100

Question 27

:

Day of week (that tool box meetings are held)?

Response No. of Companies Percent of Total

Monday 18 23

Wednesday 2 3

Thursday 2 3

Friday 6 7 No set day 38 48

Unknown 13 16

79 100

Question 28: Who attends these (tool box) meetings?

Response No. of Companies Percent of Total

The workers of a single crew

All company personnel

60

17

77

78

22

100
Question 29: Who presides at these meetings?

Response No. of Companies Percent of Total

President or owner 14 18

Foreman 38 49

Superintendent 12 16

General superintendent 5 6

Safety officer 4 5

Other (engineer, vice

president, estimator) 5 6

78 100

Question 30: How meaningful do you think they (tool box meetings) are

Response No. of Companies Percent of Total

Very essential 4 5

They do some good 33 44

Not convinced of

their value 33 44

They have no value 5 7 75 100

Question 31: Do the foremen receive any formal safety training?

Response No. of Companies Percent of Total

59 65

32 35

91 100

* Training for foremen Included first aid training, safety classes,

safety seminars, and OSHA safety training.

Yes** No

50

A
Question 32: Who Is In charge of the company safety program?

Response No. of Companies Percent of Total

President or owner 40 46

Vice President 12 14

Safety officer 17 20

Other (superintendent,

engineer, estimator) 17 20

86 100

Question 33: How often Is he (safety officer) In the field?

Response No. of Companies Percent of Total

Dally 48 58

Weekly or more frequently 25 30

Monthly 9 11

Less than monthly 1 1 83 100

Question 34: Is he (safety officer) Involved In job planning?

Response No. of Companies Percent of Total

Yes 73 90

No 8 10

81 100

Question 35: What does he (safety officer) do?

Response No. of Companies Percent of Total

Pushes on safety 18 32

akes routine

Inspections

Has minimal Involvement

16 28

in safety 15 26

Has very vague duties 8 14

57 100

51
Question 36: To what extent Is the company president Involved In

job safety?

Response No. of Companies Percent of Total

In charge of safety 10

Very much 59

Somewhat 8

Very little 6

83

12

71

10

7 100

Question 37: Who, outside the company, gives the most valuable

assistance on job safety?

Reponse No. of Companies Percent of Total

Insurance carrier 48 58

Contractor association 24 29

State or federal agency 5 6

Equipment suppliers 6 7 83 100

Question 38: What assistance do you get from the Insurance company on

job safety?

Response No. of Companies Percent of Total

Mlnlmlal assistance • 20 22

Routine assistance 44 48

Special consultation 11 12

Movies and lectures 6 7 Safety classes 1 1 No assistance 9 10

91 100

Note: Most (90%) contractors Indicated that the Insurance

carrier made jobsite Inspections; however the frequency

of such Inspections was quite varied.

52
Question 39: How often do they (Insurance Inspectors) visit the jobs?

Response No. of Companies Percent of Total

Weekly 5 6

Twice a month 5 6

Monthly 16 19

Quarterly 31 36

Yearly or less 20 24

Never 8 9

85 100

Question 40; How valuable are Insurance Inspections?

Response No. of Companies Percent of Total

Extremely helpful 24 27

Helpful 33 36

Some are helpful 6 7 Very little help 14 15

No help at all 14 15

91 100

Note; About 85% of the Inspections are described In formal

reports sent to the contractor's office.

Question 41: What Is the Experience Modification Rating* of the

Company?

Response No. of Companies Percent of Total

less than 60 3 4

60 - 69 4 5

70 - 79 13 18

80 - 89 23 31

90 - 99 12 16

100 - 120 13 18 over 120 6 8

74 100

* In relation to Workmen's Compensation premium rates.

53
Question 42: How many OSHA Inspections have occurred In the company?

Response No. of Companies Percent of Total

0 9 10

1 14 15

2-5 31 34

6-10 15 17

11 - 20 13 14 over 20 9 10

91 100

Question 43: (of those firms Inspected) How many

received?

citations were

Response No. of Companies Percent of Total

0 17 21

1 13 16

2-3 25 30

4-5 17 21

6-10 4 5

11 - 20 4 5 over 20 2 2

82 100

Question 44: How has OSHA affected your work?

Response No. of Companies Percent of Total

No effect 12 15

Increased costs 29 37

Slowed production 6 8

Hurt costs and

production 5 6

It had a bad effect 22 28

It had a minor Impact 5 6

79 100

54
Question 45: Would you connnent on your thoughts or experiences with

OSHA Inspectors?

Responses No. of Companies Percent of Total

Impractical,

lack of experience,

no common sense, etc. 54 64

Fair and reasonable 22 26

Some are good while

others are bad 8 10

84 100

Question 46: Has your accident history changed since OSHA became

effective?

Response No. of Companies Percent of Total

Yes - It's Improved 4 5

Yes - It's worse 15 18

No change 63 77

82 100

Question 47: Do you get some kind of cost history that tells you how

much each Injury claim amounts to?

Response No. of Companies Percent of Total

Yes 40 69

No 12 21

Do not know 6 10

58 100

Question 48: Are safety records considered when establishing raises?

Response No. of Companies Percent of Total

Yes 15 18

No 70 82

85 100

55
Question 49: Is there a company safety Incentive program?

Response

Yes

No. of Companies Percent of Total

11 12

No 78 88

89 100

Question 50: How does the field know that the company fully supports

job safety?

Response

The company Is strict

No_. of Companies Percent of Total

10 11

44

on safety

The company president

harps on safety

VJe stress It with the

38

foreman 4 5

Through safety meetings

and posters

Through the safety

25 29

equipment the company

supplies

Through the company's safety

5 6

personnel 4 5

86 100

Question 51: Would you say that some Injuries are just a part of the

job?

Response No. of Companies Percent of Total

Yes 51 56

No 27 30

They are caused

by carelessness 13 14

91 100

56
APPENDIX C

COMMENTS ON EMPIRICAL PRACTICES

Contractors were asked specific questions about their company

operations. In addition, they were asked to expound on any empirical

practices, or guidelines, particularly shoring practices which they

consistently followed. It should be noted that many different soil

conditions could be encountered, therefore work practices could vary

considerably.

COMMENTS MADE BY UTILITY CONTRACTORS ABOUT THEIR OPERATIONS

We shore with primarily fir members. We usually use 8 by 8's. We use

these up to depths of 15 to 18 feet. Beyond that depth we use steel

sheeting. We rarely use 6 by 6 members.

We often use 2 by 12 fir planking and use trench jacks horizontally as cross-braces.

If the backhoe teeth marks stay clearly Imprinted in the trench walls.

It Is a stable bank.

We use hydraulic shores up to 13 feet In depth. At greater depths, we

use trench boxes.

We use steel sheet piling. Instead of wood sheeting, as soon as the

.trench depth reaches 17 feet or when the width Is over 7 feet.

We sometimes use the bucket of the backhoe for trench protection. This

Is effective protection for short periods, and It Is also a safer

procedure since the trench jacks may not hold the trench.

We never retrieve the bottom walers In the trench, because it Is too

unsafe.

If the trench walls are unstable, we use (7/8" to 1") plywood backing

for the hydraulic shores.

On any trench deeper than 10 or 12 feet, we use 12 by 12 walers and

braces.

A typical spacing for skip shoring In our company is from 3 to 5 feet on center

.

In loess we don’t slope, we cut a vertical trench up to 8 feet deep.

At depths greater than that we start to bench the trench with 3 to 5

foot benches. We cut 12 feet for vertical banks In hard clays. If the

clay Is wet, however, we slope the entire trench.

57
In loess we slope or shore the trenches, no matter how hard the soil Is.

If the trench width approaches 8 to 10 feet, we use 12 steel I—beams

for struts. Otherwise we use 10" by 10" or 12" by 12" wood members.

We use a shield behind our trenching machine so that no more than 12

Inches of unbraced trench is exposed at a single time.

We use only green lumber on our shored trenches. It bends before

breaking, giving advance notice of problems.

We use 2" wood sheeting for trench depths under 12 feet. At 12 foot

depths and deeper, we use 3" sheeting.

We use trench boxes only In hard clay.

In mucky soil, we use a 4 foot toe on our sheeting or It would give way.

Often a wood floor Is essential.

We use 2" material where 14 foot long sheeting members are used. For

longer lengths, 3" sheeting is used.

We brace our trenches so that walers are spaced not more than 4 feet

apart. The top waler is 4 feet from the top of the trench and the

bottom waler Is 3 to 5 feet from the bottom of the trench. As soon as one of these dimensions Is reached, we add another waler.

In 9 foot trenches we go to 8" by 8" shoring members. In 12-foot

trenches we go to 12" by 12" shoring members, and In trenches over 20

feet deep we slope the banks. Our strut spacing In shored trenches Is

8 feet on centers.

We use 4 struts on 16 foot walers. This allows us to lower 6-foot pipe

sections Into the trench.

We don't use 4" by 6" members on any trenches over 8 feet deep.

We use wood to shore trenches that are about 12 to 14 feet deep. Beyond

that depth we use steel sheet piling.

We use 8" by 8" members for shoring trenches 8 to 14 feet In depth. At

16 foot depths (or If the width Is 12 feet) we go to steel walers and

3 Inch sheeting.

In tight timber sheeting we use 3-lnch sheeting If the trench depth Is

14 to 16 feet (Interior strut spacing of 5 feet). For shallower depths

wo use 2 Inch sheeting.

On trenches 18 feet deep we use 12" by 12" members with cross braces 8

feet apart. This would be typical for a trench that is 15 feet wide.

58
Our foremen (or superintendents) determine from a visual Inspection what

the angle of repose should be. It tends to be steep for glacial till

and low for sand. After the ditch Is dug the foreman remains at the

surface continuously to watch for cracking and sloughing.

We use trench boxes even when the soil Is very stable. Our boxes are

10 feet high and 24 feet long with various widths. We have stacked as many as three of these boxes on top of each other. If the trench Is

deeper than 30 feet, we slope that portion above the top of the upper

box.
APPENDIX D

COMMENTS ON EXCAVATION AND TRENCHING STANDARDS

Information regarding OSHA and the OSHA trenching standards was obtained

by telephone calls, personal conversations, letters, and questionnaire

responses. Comments were made by contractors, contractor association

officers, construction workers, engineers, educators, safety consultants, municipal officials, and equipment suppliers. These comments are presented herein to provide additional Insight Into trenching safety

concerns. Some of these comments present specific or general problems,

while others present possible solutions.

COMMENTS ON OSHA TRENCHING TABLES P-1 AND P-2

OSHA should change the soil conditions and depth requirements before

shoring or sloping Is required.

Experience and common sense cannot be put Into a table or diagram.

We feel that In stable soil no bracing should be required In a situation

where sloping may be done from a point 5 feet above the bottom of the

trench. The bottom 5 feet would not require bracing where sloping may

be done above that level.

There should be a complete revision of Tables P-1 and P-2 to reflect

varying soil composition, different moisture conditions, and a method of

accurately evaluating shoring requirements as they exist on the job.

From depths of 5 to 12 feet, soil conditions should dictate the use of

shoring. Stiff clay does not need to be sloped at 45 degrees.

Tables P-1 and P-2 should be revised so they can be more easily read and

understood.

The requirements are very much overdesigned.

A contractor can still be cited by trying to follow these guidelines.

They do not consider time In safety. Trench walls should hold up a short time, not a lifetime.

If the trench Is over a man's head, some protection should be provided.

Those tables are satisfactory for permanent (10 to 50 years) excavations

only.

These tables are antiquated and not responsive to varying soil conditions .

60
COMMENTS ON OSHA SLOPING REQUIREMENTS (TABLE P-1)

There should be liberalization of sloping requirements to allow less

slope. Allow the contractor more options In which he can use judgment.

Change the sloping requirements to start at the 5 foot elevation, not

the bottom of the trench.

Allow 1/2 to 1 slope In good ground conditions.

The sides of the trench should not be steeper than 1-foot rise to each

1/2 - horizontal run In unstable soil. Otherwise, the decision should

be made by a competent person, one who Is knowledgeable about the

soils in the particular area.

Mixtures of soils must be accounted for In Table P-1.

OSHA should establish a slope guideline within each local area that

would be specific to the conditions that exist.

The wording of "approximate angle of repose" Is most deceptive and that

should be reworded and made realistic.

Many soils will stand with less slope than Is now required, especially

when ditches are only open for short periods of time.

The sloping requirements are not practical. It requires way too much

digging for a safe trench.

Revise Table P-1; It Is not realistic to require 45 degree slopes In

hard compact soil. The word "average" Is too broad.

Most highway cuts are 1 1/2 to 1, yet OSHA shows that a ditch slope at

2 to 1 Is required.

"Cemented sand and gravels," what are they?

Sloping requirements In ditches need to be modified. Where pipelaying

and backfilling follow immediately behind the digging operation, sloping

at 1/2 to 1 Is adequate. In wide ditches, effective slopes of the sides

should be measured from the center of the ditch Instead of the sides of

the ditch.

The angles of repose should be lessened and sloping should start 4 feet

above the bottom of the trench In soils which will allow this.

The angles of repose used In the OSHA standards are for disturbed

material. Our trenches are dug In virgin, undisturbed soils which have

higher angles of repose.

It Is Impossible to dig a trench in a 30-year-old road bed and conform

to the OSHA sloping requirements.

61
The slope cannot be below the top of the proposed pipe as specified in

all specifications.

Clay should not have to be braced. We need research on better methods.

Allow for sloping clay.

Slopes on solid rock should not be vertical. Two-in-one slopes on a ditch are impossible in many cases due to right-of-way constraints.

Sloping a ditch to the bottom of the ditch is asinine. A vertical bank

should be determined by the width of the trench. A higher wall should

be allowed in the wider trenches. In joint clay, however, this is not

applicable.

The standard should allow for sandstone and shale which stand up like

rock.

In loess soil, a vertical bank is safer than a sloped bank.

Municipalities do not provide enough right of way to slope banks in many

cases

.

COMMENTS ON OSHA SHORING REQUIREMENTS (TABLE P-2)

Spacing of trench bracing could be more lenient and trench depths could

be lowered for minimum use of shoring. Most 4 to 6 foot trenches in our

soil (very hard clays) do not need shoring and often trenches up to 10

feet do not need it.

Table P-2 should be revised to conform with empirical practices.

Trenchwork needs to be removed from table-type regulations. Control

should be by additional training of personnel.

Revise Table P-2. Upright spacing for trench depths of 5 to 15 feet in

hard compact soil is unreasonable.

Supervisors on the job need the authority to make on-the-job decisions

as to the bracing requirements.

Shallow ditches in good ground up to a 6- or 7-foot depth do not need

to be braced, especially waterline ditches.

Let contractors design their own sheeting and shoring since they are responsible. Make everyone shore below a certain depth, but 5 feet is

too shallow; possibly 7 feet would be more realistic.

Field conditions are too variable to be defined by tables.

Minimum dimensions of stringers in depths over 20 feet are less than for

depths of 10 to 15 feet.

62
Table P-2 is good for wide open areas with nothing in the way. Engineers

do not design jobs in clean open areas.

Table P-2 is unrealistic due to member size and spacing. The table, if

followed, would grossly restrict work. Normal pipe lengths used today

could not get into the trench through the forest of bracing.

It is difficult to put a 10-foot length of pipe into a trench that has

crossbraces spaced at 6 feet.

It is very difficult to install some lengths of pipe when you adhere

fully to brace spacing requirements.

A 6-foot brace spacing is impossible if a clamshell is to be used inside

the shoring.

It is impossible to completely comply with the OSHA standards if the

trench crosses an existing utility line.

COMMENTS ABOUT TRENCH BOXES

I am not sure if the trench box is legal by OSHA standards. If not, I think it should be.

OSHA should recognize trench boxes as temporary sheeting.

OSHA should evaluate and strongly recommend the use of engineered steel

trench boxes, with automatic fine credits given to those contractors who

use them.

OSHA should be more flexible and realistic. You can allow the trench

shield (trench box) to ride a few feet off the bottom of the trench and

still not jeopardize any employees.

The definition of a trench shield is wrong. OSHA should not specify

that it protect the trench from the top to the bottom. Shoring should

start at the top of the installation, i.e., protection should start at

the top of the pipe in the trench.

We need clear and reasonable trench box standards.

More allowances should be made by engineers permitting wider trench

widths and then the use of more trench boxes can be possible.

COMMENTS ON THE "LADDER IN TRENCH” REQUIREMENTS

Backfill in the trench should be allowed as a means of exit when the

backfilling operation is close behind the trench box.

The ladder problem must be redone.

63
In trenches where larger diameter (60") pipe is laid, the pipe should

be permitted to be used as a safety escape. It is easier to get

into the pipe than to wait in line to get out of the trench by way of a ladder.

Ladders in big pipe trenches are unsafe. It is far safer to jump into

the pipe if it is a 48" diameter pipe.

Why is a ladder needed in a trench that is sloped? If the trench is

shored, why require a ladder?

Ladders in a trench can actually create a hazard.

We were fined once for not having a ladder in the trench. We were

moving the ladder forward at the time.

A ladder in a trench impedes escape if a sloped bank caves in.

Ladders in a muddy trench bottom will sink if a worker uses it. It is

actually more dangerous with the ladder.

Where do you put the ladder if the backfilling operation is close behind

the pipelaying operation. It is in the way. It is not necessary to

have a ladder if the backfill is close and the banks are sloped so people can exit by them.

COJ^E^NTS REGARDING VARIOUS TRENCHING PROVISIONS

The four-foot bench reqairement on large diameter pipe seems arbitrary.

Trenching machines have conveyors. The bulldozer pushes dirt away from

the conveyor, but it will not pass under the conveyor with a roll-over

bar.

OSHA and consulting engineers should explain how a trench can be handtamped and backfilled without tight sheeting.

An on-site test of trench wall stability is by scaling (striking) the

walls with the backhoe bucket. If the walls do not cave-in with this

scaling, the walls will never cave in. This method has never failed in

16 years of experience in digging by open cut method over 200,000 feet

of trenches up to 31 feet in depth.

There should be a practical standard procedure for installing welded

steel pipeline in a shored trench.

Consideration should be given to the type of surface we pile dirt on adjacent to the trench.

The widths of trenches should be unlimited.

64
If the embankment is hard and compact and will stand alone for 24 hours,

they should then do away with the 5-foot minimum required standard for

bracing

.

Most of our trenchwork is in city streets with 8" - 12" of pavement. We

feel that this prevents the shear of the trench walls for medium depth

trenches

.

I wish our local (OSHA) office would recognize our use of hydraulic

shores with 3/4" plywood sheeting.

Contractors should determine the type of soil and establish procedures

of operation if specifications do not apply.

In unusual situations, let the contractor submit a proposed plan or method for approval.

OSHA should accept 1" plywood for bracing when used with air, hydraulic

or screw jacks.

For a manhole excavation next to an existing utility line, you have to

put a man in the hole to put in the shoring.

Close sheeting should not be required if the trench is over 15 feet

deep. We prefer to use double trench jacks in these deep trenches.

Back-up alarms on equipment make people nervous. The workmen get used

to the sound and it is not any safer. Some workers wear ear plugs and

then they cannot hear it anyway.

OSHA should put more emphasis on hydraulic shores.

It is impossible to store material more than 2 feet from the trench if

you are forced to leave room for public traffic.

On big jobs, our company has a man on top of the trench who looks for

tension cracks constantly all day.

We cannot slope back into an area that has an existing utility.

Back-up alarms do not stand up under dust, moisture, and vibrations.

Roll-over protection is not necessary in flat areas.

Workers on heavy equipment will not use seat belts.

We would like to see an acceptance of compound sloping. This is where

the bottom five feet of a trench can be vertical and the rest is sloped.

The standards do not specify the type of wood to be used in shoring.

65
COMMENTS ON THE NEED TO CONSIDER SPECIFIC CONDITIONS

Shoring requirements need to be suited to each area.

Compaction, type of soil, knowledge of soil, etc., need to be considered

when determining the angle of the slope or the necessity of a trench

box.

The OSHA requirements should be set more on a local level, otherwise

they are too general.

There should be flexibility to incorporate the specific conditions that

exist on each job.

Judgement rights should be restored to company experts to determine

trench slopes under the continuously changing conditions in which we

work.

Since soils and soil conditions vary considerably throughout a job, OSHA

should allow the contractor to make his own determinations on slopes,

bracing, etc., in conjunction with the OSHA standards.

Standards should not be the same for urban and rural areas.

OSHA standards l926-653(h) should be redefined by noting various types

of soils.

They should take into consideration the actual conditions that exist;

use a little common sense.

There should be more consideration given to job conditions and the

specific safety methods that are most appropriate, regardless of the

general dictates of the OSHA standards.

Each state must have its own specifications on soils.

Permit competent persons, preferably engineers, to make determinations

as to trenching requirements. However, penalties for willful violations

should be severe.

Existing utilities present problems to contractors, but this is not

often realized by OSHA.

OSHA should be geographically oriented.

COMMENTS ON SOIL CLASSIFICATIONS AND SOIL CHARACTERISTICS

A greater effort is needed to classify soils and trenching conditions

as tliey exist in the field; five or six classes cannot cover the various

conditions experienced on a national level.

66
OSHA should have standards written by experienced trenching personnel,

experienced in the particular soils being encountered in specific

circumstances

.

More consideration should be given to soils encountered that are substantially more stable. Example: some areas filled with poured slag

that has cemented and is very stable should not require shoring.

There are no provisions for loess materials.

Inspectors will not allow for cohesion in the soil caused by root

systems

.

Before a fine is imposed, soil conditions should be analyzed. Some hard

gravels and hard clays are like rock and will stand up.

The standards do not allow for analysis of soils in lieu of Table P-1.

COMMENTS ON POSSIBLE CHANGES IN BIDDING POLICIES

OSHA should insist that Engineers specify that payment to contractors

shall be made for any additional width of trench which is made necessary

for OSHA compliance. The fixed specified widths of trenches indicated

by engineering consultants in their plans and specifications often

conflict with the OSHA standards.

Since OSHA is enforced for private firms, municipalities and other

authorities should comply. OSHA should force engineers and municipalities to pay for proper trench widths and they should also include

pavement as a pay item.

On cross sections for trenches, the states and design engineers should

be required to use the same cross sections as those required (by OSHA)

of the contractor, especially if backfill is a pay item.

If I bid my projects with all inclusions for necessary expenses for OSHA

compliance, everyone should include it in his bid.

Bidding should be handled so that tight sheeting, would be regarded as an

extra if it is needed. This would eliminate guesswork and the contractors' bids could be more equitably compared.

Specifications should allow the guesswork to be removed regarding the

necessity of tight sheeting, etc.

The angle of repose should be Included in the specifications.

Owners should specify the shoring price.

Shoring as a bid item would be good.

67
Shoring as a bid item is good. It keeps the small guy or the bad guy

from getting the bid when he did not Include shoring.

The owner has to specify the type of shoring so everyone bids the same

thing. This puts the responsibility on the owner's back. The owner should also have to check that the contractor is complying.

If shoring is put in as a bid item, the contractor can unbalance his bid.

Contractors do not oppose having shoring as a bid item. They want to get

paid for what they do.

GENERAL COMMENTS ABOUT TRENCHING AND THE OSHA TRENCHING STANDARDS

1 have not read it (OSHA trenching standards) since I first reviewed it

and discovered it had no relationship with reality.

Trenchwork should be separated from excavations.

Attempt to be more specific. Have contractors and soils engineers

combine their talents along with the legal profession in rewriting this

entire section of the standards.

No one wants to bury a man, no matter what.

The rules are not practical and do not allow for particular job conditions. Consulting engineers should be made responsible to design jobs in

a manner that makes it possible for a contractor to build the jobs within

existing safety rules and regulations.

We know what is safe and what is not safe. We try in every case to be

conservatively safe.

OSHA should use standards as stated in the state of Wisconsin Administration Code. This code has been tested and proven to be a sound code. It

Is workable in all soil conditions.

The specification standard should be changed to performance standards to

include recommended guidelines.

There should be separate regulations for trenching.

A soil in which five foot unshored walls are safe would require more than

2 1/2 times the volume of excavation and backfill if the depth were

increased to 5 1/4 feet. The spoil bank occupies more than 3 times the

surface area which in conjested traffic locations can create unsafe con- ditions. There is a need for a provision in the standards for varying

combinations of vertical and sloped walls which will provide equivalent

safety to the 5' vertical wall without the expense of unnecessary earth

hand 1 1 ng .

68
Where soil tests and engineering analysis indicates that specific

compound trench slope designs meet the safety standards, the contractor

should have reasonable assurance before bidding the job that he will

be allowed to utilize such designs and that their acceptance will not

entail such delay as to discourage their use.

Table P-2 should be replaced by a new table which refers to the strength

of the material and a standard of performance rather than a specification.

GENERAL COMMENTS ABOUT SAFETY, OSHA AND THE OSHA STANDARDS

Contractors need to review and add grass roots to standards in concert.

OSHA needs to be less police oriented and be more educational.

I would like to see the standards applied fairly to all instead of

strictly to some and not at all to those who are "buying off" state and

Federal Inspectors. The incidence of "buying off" (State) OSHA inspectors by a few contractors is most troublesome in our area.

OSHA should refrain from harassing contractors.

OSHA standards should be more realistic and flexible*

OSHA should pay for schooling workers in safety.

I think the whole thing should be restructured. We need people who have

practical on-the-job experience.

OSHA standards should reflect common sense.

OSHA standards should be simplified.

OSHA should make the standards more realistic.

Everyone should be forced to comply the same.

We should get rid of OSHA.

Instead of being police, they should be more helpful in correcting

violations. They should not just be punitive, but rather they should

make visits and correct problems.

Why does OSHA have no jurisdiction over cities and the federal

government?

We want to be safe. So OSHA should come on my job. But work with me in

being safe, l.e., do not play police.

If insurance companies did their job, OSHA would not be needed.

69
We can buy the hard hats but we cannot make the workers wear them; we cannot afford to fire our best workers.

We would never work if we complied 100%.

Owners should also be responsive to OSHA regulations.

They should allow pre-construction meetings between OSHA and the

contractors

Unions use OSHA to get at the contractors.

OSHA should give advice and be hand-in-hand safety partners with

contractors. Then you would have cooperation and more safe conditions.

OSHA does not have time to come to our company planning meetings.

If I would comply fully with OSHA, I would go out of business.

OSHA takes for granted that you are doing something wrong.

We need on-site consultation.

We are drowning in bureaucracy.

It is not worth a life to take a chance.

Who can I realistically go to, to get advice on OSHA?

In wanting to be safe, I cannot get advice from OSHA.

OSHA should stop the cloak and dagger approach and really advise people.

No one wants anyone hurt.

OSHA should put on some safety courses (for each trade) and tell

contractors what they want.

We cannot get advice without jeopardizing ourselves.

OSHA’s approach to a contractor has to be one of help rather than of

fining and condemning.

Consideration should be given to the type of contractor and contractor

practices that actually kill a lot of people.

It is apparent to most contractors that the costs of injuries directly

affect the costs of insurance. It is not apparent, however, to what

extent these costs are affected. It is clear from the little knowledge

that many contractors have about insurance costs, as reflected to some degree in Workman's Compensation Experience Modification Rates, that

education in this area has been poor.

70
OSHA Inspections do not seem to be random.

COMMENTS ABOUT OSHA COMPLIANCE OFFICERS

OSHA should have inspectors who are technically competent to survey the

worksites

OSHA should allow inspectors some leeway with regard to the interpretation of the laws.

OSHA needs qualified inspectors, not shoe salesmen.

They should have Inspectors with construction experience and they should

stay with one rule.

Inspectors should be knowledgeable about all conditions and they should

make recommendations at the jobsites.

Citations should be issued only when professional engineers with extensive experience in trench safety deem the trench to be unsafe. I submit

that only an experienced professional can make a rational judgement on this issue—not the average OSHA inspector. The inspectors should have

available to themselves such professional assistance when it is needed.

Possibly, OSHA could use inspectors with construction experience who can

judge the safety of a trench based on their experience while using the

standards as a general guideline.

OSHA should have some inspectors with some actual experience in trenching and excavations. This would be better than the inspector we recently

had who was an Illiterate steel worker who had never worked around or had

any knowledge of excavations.

OSHA compliance officers place too much emphasis on the exact measurement of trenches.

All inspectors make their own rules.

Sometimes special conditions are treated in too much of a textbook

manner. We have all seen 5-ft. trenches that were dangerous and 8-ft.

trenches, with less than 1 on 1 sloping, that were safe. Inspectors go

by the book, not by realistic judgement.

Inspectors should stop nit-picking.

OSHA Inspectors feel they have to justify their jobs by fining

contractors

We would not hire them as safety engineers.

They are not necessarily well-endowed with common sense.

71
OSHA needs to establish some method of credibility for field personnel

to assure that they are experienced in judging shoring requirements.

They should consider if life is actually endangered, not if a law is not

strictly adhered too.

Inspectors should visit private work projects.

COMMENTS ABOUT THE OSHA FINING POLICIES

On first visits to the job sites, OSHA should not fine the contractors.

They should issue warnings and not fines for the small problems.

I believe their rules should not be sp cut and dry. Possibly they

should give more responsibility to their compliance officers and let

them be the final judge as to whether or not a rule has been bent too

much

Fines should be assessed on an experience rating basis, based on each

firm's record of accidents.

The regulations should be set up so that ff an accident occurs and the

contractor made a bad judgement, hp should be fined.

On-the-spot citations should be eliminated. Instead, the inspector

should first give the contractor a writften order to comply and give the

contractor a reasonable time to make the corrections.

The ability to pay seems to determine the amount of the fines. The area

director, who did not see the violation, sets the amount of the fine,

not the Inspector.

OSHA should not fine the contractor right off. They should give the

contractor a little time to correct the problem. If it is not promptly

corrected, then fine the contractor.

Why don't we have free inspections without the risk of fines.

Even though we may feel justified in contesting a citation, it costs us

too much to defend our position.

COMMENTS ON WORKER RESPONSIBILITIES FOR SAFETY

We would like to see more responsibility placed on the employees. If

the person is doing something he knpws to be unsafe, why is the contractor fined or punished for this?

Responsibility for safety is now totally with management. It should be

shifted somewhat to the workers.

72
If a company truckdriver is caught speeding on the highway, the truckdriver pays the fine. However, if the same worker is caught driving

recklessly on a construction jobsite, the contractor is obligated to pay

the fine. The law is inequitable in that regard.

73
APPENDIX E

NATIONAL UTILITY CONTRACTORS ASSOCIATION (NUCA) STUDY

74
NATIONAL UTILITY CONTRACTORS ASSOCIATION INC.

815 Fifteenth Street, N.W. , Washington, D.C. 20005

Phone Area Code 202 737-0037

December, 1976

Dear Contractor:

As a result of wide-spread concern, the Occupational Safety and Health

Administration (OSHA), has asked the National Bureau of Standards to

reevaluate its trenching standards and to conduct an investigation of

the technical aspects of trenching safety.

Since the climate now seems ideal for a vigorous industry response to

this re-evaluation, we are seeking a broad range of contractor opinions

and recommendations on the current standards. You can help to provide

input into this Important study by completing the enclosed questionnaire

and returning it to the NUCA National office as soon as possible.

It appears that some definite changes will be made in the trenching and

shoring standards, and we feel we have both an opportunity and a responsibility to see that this re-evaluation effort contains the thoughts and

recommendations of the Nation’s Ditchdiggers who are on the firing line.

If you have any questions, please feel free to contact the National

office. Results of the survey will be made available to participants

upon request.

Cordially,

John H. Pannullo

Executive Director

JNP:pdf

75
QUESTIONNAIRE FOR CONTRACTORS WHO DO WORK WHICH INVOLVES TRENCHING

1. Your job title in the company:

2. Type of trench work that the company generally does: (circle

appropriate ones)

storm sewer sanitary sewer water gas telephone electric

other:

3. In which geographic area (or state) does the company do most of its

work?

4.

Approximately what percent of the total dollar volume of work

done by the company involves trenchwork? (circle one)

0-25% 26-50% 51-75% 76-90% over 90%

5.

Which of the following types of soils do you most frequently

encounter? (circle one)

sand

sand & gravel

soft to medium clays

other:

- stiff clays

- very hard clays

- rock

- clayey sands or sandy clays

6. Is the soil wet or dry? wet dry other:

7. Approximate depth to ground water table: (circle one)

0-5 ft 5-10 ft. 10-15 ft» 15-20 ft over 20 ft.

8. Describe a trench which is most typical of the type of work that

you do: (circle the answer that is most typical)

A. Trench depth: 0-5 ft. 5-10 ft. 10-15 ft. 15-20 ft.

over 20 ft.

B. Trench width (at bottom of trench):

ft. 3-6 ft. 6-9 ft. 9-12 ft. over 12 ft.

76
C. Length of trench that is left open at one time (distance from

back-filled portion of the trench to the backhoe):

0-25 ft. 25-50 ft. 50-75 ft. 75-100 ft.

100-150 ft. 150-200 ft. 200—400 ft. over 400 ft.

9.

What percent of the trenches are not braced but sloped? (circle one)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

When trenches are shored (braced), how often are the following used?

trench box: %

timber bracing:

tight timber sheeting: Z

other: :

hydraulic shores: %

screw jacks: %

sheet piling: %

%

10.

On what occasions has the company hired a soils engineer?

(check one)

- we have our own engineers

- we never have

- only before major bids

- when the owner didn't supply sufficient Information

- only when legal problems arise after the job starts

- other:

11.

In the OSHA standards, contractors are provided with guidelines as

set forth in Tables P-1 and P-2. How clear and useful are these

tables? (check one)

- very helpful

- a guide for our company

- too general to be a helpful guide

- not realistic for our work situations

- other:

Please comment:

12.

I'/hat specific changes would you recommend to be made in the OSHA

standards regarding "Trenchwork and Excavation?"

77
13.

What are your thoughts or experiences with OSHA compliance officers?

(check one)

- they really do Identify safety hazards

- they mean well but they don't understand construction work

- they Interpret the OSHA regulations to the letter of the law

- they are just out on the jobs to fine the contractor

- other comments:

14.

Have any OSHA Inspections occurred on your company jobs: yes no

If yes, how many Inspections have been made?

how many of these Inspections occurred as the result of an accident?

how many inspections resulted in citations?

what was fhe maximum fine?

15.

Does the company have a safety Incentive or safety award system?

yea no

If yes, what is the award?

who receives the award? _

16.

Are tool box (safety) meetings held on the job sites? yes no

If yes, how often are they held?

(circle one)

weekly biweekly

quarterly

When are they held? Monday Tuesday Wednesday

(circle one)

Friday No set day of the week

Who presides at these meetings? (circle one)

monthly

annually

Thursday

- assigned worker - job supervisor

- foreman - safety man

- president or owner

- other:

Does the company ever have any other meetings that Involve safety?

yes no

78
17.

What type of safety orientation do the new hires receive? (check one)

- no safety orientation

- informal safety orientation

- formal orientation, describe briefly:

18. Have any of your employees ever been fired specifically for violating

trenching safety standards?

yes no

19. Who does the company generally hold responsible for job injuries?

(circle one)

- injured worker - foreman - superintendent

- other;

20.

How much assistance does the company get from the insurance company

on safety? (check one)

- they are very helpful through their job inspections

- they Inspect the jobs but they are not very helpful

- they send us brochures and safety information

- they only get concerned after accidents

- other:

21. How many recordable injuries occurred in the company in 1975?

Of these injuries, how many were lost time injuries?

22. What is the insurance experience modification rating of the company?

(Since this particular information is of extreme interest in this

survey, please try to provide this information.)

23.

Approximately how many man-hours were worked by company forces in

1975?

man-hours

24.

What is the average number of field workers on the company payroll?

minimum number: maximum number:

79
WE WOULD ALSO LIKE TO HAVE SOME GENERAL INFORMATION ABOUT YOUR FIRM

25. Approximate annual dollar volume of the company: $ million

26. How many people does the company employ in the office ?

27. Of the field employees, approximately what percent has been with

the company for longer than one year? (circle one)

0-20% 20-40% 40-60% 60-80% 80-100%

How many have been with the company for longer than 5 years?

(circle one)

0-20% 20-40% 40-60% 60-80% 80-100%

28. Type of contractor; Union Merit Shop

29. Approximately what percent of the company's work is obtained through

competitive bidding (not negotiated)? 7c bid

30. How many workers regularly visit the premises at the home office?

(circle one)

0-20% 20-40% 40-60% 60-80% 80-100%

31. What percent of the company work is done within 25 miles of the

home office? (circle one)

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

32. What kind of cost information is given to the foremen? (check one)

- they are given exactly what is in the estimate

- they are given only a rough idea of what is in the estimate

- they are told only if they are behind schedule or over budget

- they are not given any cost information

- other:

33. How often does the president (or an owner) visit most job sites?

(circle one)

- dally - 3 times a week - 2 times a week

- 2 times a month - 1 time a month - less than monthly

80
34. Does the company have a pension fund or profit-sharing plan for the

field workers?

yes no

35. What kind of communication does the company have with the jobs?

(check appropriate ones)

- home office people frequently visit the jobs

- most jobs have CB radios for home office communications

- telephones are available at most jobs

- top management is stationed on the jobs

- other:

81
PARTIAL SUMMARY OF NUCA QUESTIONNAIRE RESULTS

CORRELATION BETWEEN VARIABLES

Increase in

Injury Frequency

Increase in the

Company Annual

Dollar Volume

Increase in the Annual Dollar Volume K = .21 K = 1.00

of the Company N = (199) N = (203)

sig .001 Sig = .001

Increase in the Number of Field Workers K = .21 K = .73

in the Company N = (156) N = (155)

Sig .001 Sig — .001

Increase in the Number of Manhours K =; .24 K = .66

Worked in the Company N = (181) N = (178)

Sig .001 Sig — .001

Increase in the Number of Home Office K = .22 K = .67

Employees in the Company N - (201) N = (198)

Sig = .001 Sig = .001

Decrease in the Amount of Work Done K =s .13 K = .24

Within 25 Miles of the Home Office N = (202) N = (199)

Sig = .003 Sig = .001

Decrease in the Number of Workers Who K = .09 K = .32

Have Occasion to Visit the Home N = (197) N = (194)

Office Premises Sig = .03 Sig = .001

Decrease in the Number of Times the K =: .23 K = .42

Company President Visits the Job N = (200) N = (198)

Sites Sig = .001 Sig = .001

Decrease in the Number of Workers Who K ss .08 K = .16

Have Worked for the Company for More N = (194) N = (193)

Than One Year Sig = .05 Sig = .001

Decrease in the Number of Workers Who K .16 K .07

Have Worked for the Company for More N = (187) N = (186)

Than Five Years Sig = .001 Sig = .07

Decrease in the Percentage of Trenchwork K = .09 K = .18

Comprising the Company Volume N = (203) N = (199)

Sig = .03 Sig = .001

Increase in the Length of Trench Typically K = .08 K = .03

Left Open N = (194) N = (189)

Sig .04 Sig = .29

82
Increase in the Number of OSHA Inspections K = .19 K = .31

Following Accidents N = (193) N = (189)

Sig = .001 Sig = ,001

Increase in the Amount of the Maximum Fine K = .11 K = .28

Levied by the OSHA N »= (194) N = (191)

Sig = .009 Sig = .001

K = Kendall's Correlation Coefficient

N = Sample Size

Sig = Level of Significance

KEY:
APPENDIX F

NATIONAL ASSOCIATION OF PLUMBING, HEATING AND

COOLING CONTRACTORS (NPHCC) STUDY

1. Trench Work Performed

Storm Sewer

Sanitary Sewer

Water

Gas

Added

87 Units (or Responses)

90 Units

90 Units

77 Units

Disposal Systems

Steam Lines

Interior Storm, Solid Waste & Vent

Underground Fueling Station

3 Units

2 Units

1 Unit

14 Units

2. Percentage of Total Dollar Volume

0% 3 Units 60% 2 Units

5% 8 Units 70% 5 Units

10% 41 Units 80% 0 Units

15% 4 Units 90% 0 Units

20% 20 Units 100% 0 Units

25% 0 Units

30% 2 Units

35% 0 Units

40% 9 Units

45% 0 Units

50% 0 Units

Soil Conditions

Sand 10 Units

Sand & Gravel 19 Units

Soft-Medium Clays 42 Units

Stiff 1Clays 10 Units

Very Hard Clays 2 Units

Rock 4 Units

Clayey Sands or Sandy Clays 4 Units

Others ;

Coral 3 Units

All 26 Units

84
4 Soil Conditions

Dry 47 Units

Wet 5 Units

Combination 41 Units

No Response 1 Unit

5. Depth to Water Table

0-5 ft

5-10 ft

10-15 ft

15-20 ft

Over 20 ft

Variables

No Response

6. Trenches

a. Depth

0-5 ft

5-

10 ft

10-15 ft

15-20 ft

Over 20 ft

b. Width

0-3 ft

3-6 ft

6-

9 ft

9-12 ft

Over 12 ft

c. Length

0-25 ft

25-50 ft

50-75 ft

75-100 ft

Over 100 ft

7. Precent Sloped

0% 0 Units 60% 0 Units

10% 13 Units 70% 3 Units

20% 8 Units 80% 0 Units

30% 0 Units 90% 33 Units

40% 9 Units 100% 18 Units

50% 10 Units

4 Units

23 Units

45 Units

9 Units

4 Units

7 Units

2 Units

9 Units

77 Units

8 Units

0 Units

0 Units

83 Units

7 Units

4 Units

0 Units

0 Units

11 Units

16 Units

33 Units

24 Units

10 Units

85
8 . Soil Engineer

0 Units - We have our ovm

52 Units - We never have

19 Units - Only before major bids

7 Units - When the ovmer didn't supply adequate information

15 Units - Only when legal problems arose after the job started

0 Units - Other

1 Unit - "When specified and called for"

9. OSHA Standards

8 Units - Very helpful

45 Units - A guide for our company

9 Units - Too general to be a helpful guide

29 Units - Not realistic for our work situations

0 Units - Other

1 Unit - "Didn’t really cover our situation"

1 Unit - "Field conditions apply"

1 Unit - "Too hard to understand"

10. Specific changes; comments:

"Investigate the realistic conditions and economic impact on the

industry"

"Make employee responsible when not following instructions"

"Use of common sense"

"Let the contractor determine the requirements on an Individual job

basis"

"Review each job individually"

"There is not enough responsibility or liability put on the worker"

"Common sense"

"Stricter enforcement"

"Very good"

"Quite extensive; overall changes including ways of testing soils

by own people"

"More round table discussion"

"When OSHA fines you over $100^ he should have an engineer verify

dangerous"

"More direct to area"

"No fines for non-serlous violations"

"OSHA in our business is necessary for protection of employees but more common sense is needed to do a good job. I am proud of our

job record but we still got fined unjustly. Takes more time to

fight it than to pay and be guilty. I would like to have a perfect record but without inspectors; with common sense; I give

up

.

86
11.

OSHA Officers

I

j 9 Units

I 47 Units

j

31 Units

I 5 Units

I

I 0 Units

I 1 Unit

1 Unit

They really do identify safety hazards

They mean well but they do not understand

construction work

They interpret OSHA regulations to the

letter of the law

They are just out on the jobs to fine

the contractor

Other comments

Evaluate complete situations before acting

No common sense

12.

OSHA inspections - have they occurred?

83 Yes

3 No

8 No

Frequency

1 Unit -

5 Units - 25 Units -

43 Units -

1 Unit -

3 Units -

4 Units -

12 Units -

Fines?

28 Units - 61 Units -

5 Units -

Reasons

response

4/month

2/month

1 month

1/2 month

1/3 month

1/6 month

1/ year

No response

Yes

No

No response

"Sloping

"Ditch not shored"

"Inadequate shoring"

"Laborer had removed trench jack and got down into ditch while

safety inspector was watching unsafe act."

13.

Do members have safety programs?

76 Units - Yes

18 Units - No

t

87
14. Wliat type of safety program?

2 Units - No safety orientation

80 Units - Informal safety orientation

12 Units - Formal orientation, describe briefly...

"Signed statement from employee that he has read and understood

company safety program"

"Union should train (claim to be)"

"Meeting once a week"

"Safety course offered by trade association throughout the year"

15. Employees fired related to unsafe acts

2 Units - Yes

82 Units - No

10 Units - No response

16. Who is responsible for Injuries?

injured worker

foreman

Superintendent

Other

Contractor

Owner

No response

17. Insurance Company - Assistance

They are very helpful through their job inspections

They inspect jobs but they are not very helpful

They send us brochures and safety information

They only get concerned after accidents

Other

"They were helpful in most any way when asked"

"We have constant inspection from our carrier company"

"None (they cancel if too many accidents occur)"

18. Average number of field workers?

8 Units - 0-10 3 Units - 70-80

25 Units - 10-20 1 Unit - 80-90

13 Units - 20-30 5 Units - 90-100

4 Units - 30-40 11 Units - 100-500

9 Units - 40-50 6 Upits - 500-1000

1 Unit - 50-60 4 Units - 1000-2000

2 Units - 60-70 2 Units - No response

7 Units -

0 Units - 77 Units -

7 Units -

0 Units -

1 Unit -

1 Unit -

1 Unit -

19 Units - 27 Units -

15 Units -

0 Units -

18 Units -

1 Unit -

14 Units -

88
19 Approximate dollar value

I

f

1

I

8 Units

27 Units

17 Units

2 Units

8 Units

9 Units

12 Units

6 Units

5 Units

.25-. 5 mil

.5-1.0 mil

1.0-

1. 5 mil

1.

5-

2.0 mil

2.

0-

2. 5 mil

2.

5-

5.0 mil

5.0-

10.0 mil

Above listed

No response

20. Type of contractor

36 Union

33 Merit

23 Combination

2 No response

12 mil, 25 mil, 33 mil

21. Trenching done by member

42 Units - Primarily subcontracted

4 Units - Done by member with rental equipment

45 Units - Done by member with own equipment

3 Units - No response

I

89
APPENDIX G

REPORT OF THE BUILDING AND CONSTRUCTION

TRADES DEPARTMENT, AFL-CIO

90
TRENCHING HAZARD IDENTIFICATION TASK FORCE

Final Report

April 25, 1977

Prepared for the

National Bureau of Standards

Building Safety Section

James 0. Bryson, Chief

By

Building and Construction Trpdes Department

AFL-CIO
FOREWORD

Special acknowledgement is given for the contents of this report to Task

Force members Clifford Ahlquist, Carl Gill, Robert L. Mack, Jerry Martin,

Charles L. Stover and Robert E. Wood for their sincere efforts and

insight into the problems addressed by the Task Force.

Others contributing to the design and Implementation of the Task Force were Jack Wilkinson, Regional Manager, Laborers’ International; Joe Adam,

Safety and Health Director, United Association of Plumbers and Pipe Fitters; Robert Glenn, Business Manager, Laborers’ District Council; Mike

Collins, Business Manager, Plumbers Local //5; Martin P. Nygard, Plumbers’

Local #630, W. Vernie Reed, General Secretary-Treasurer, Laborers’ International Union.

The Task Force was chaired by Jack L. Mickle, Civil Engineering Department, Iowa State University. Technical Observer from the National Bureau

of Standards was Felix Y. Yokel.
TRENCHING HAZARD IDENTIFICATION TASK FORCE

-MEMBERSClifford W. Ahlquist

Contractor

Box 10, Rd. 2 Laurel, MD 20810

(301) 953-7029

Carl F. Gill, Sr.

Plumbers Local Union //5 Master Plumber & Gasfitter

3901 Queensbury Dr.

Hyattsville, MD 20792

(301) 864-7530

Robert L. Mack, Sr.

Laborers’ Local #74

Laborers' Instructor

2122 4th Street, N.W.

Washington, D.C. 20002

Jerry Martin

Director of Safety, Occupational

Health and Training

474 Valencia Street

San Francisco, CA 94103

(415) 431-1568

Charles L. Stover

Safety Director

Operating Engineers Local #77

4546 Brittania Way

Suit land, MD 20023

(301) 899-6400

Robert E. Wood, Jr.

Local Union #630

Journeyman, Plumber-Pipefitter

11456 Kidd Land

Lake Park, FL 33410

-STAFFCoordinator

Jim E. Lapping

Director, Safety and

Occupational Health

Building and Construction

Trades Dept., AFL-CIO

815 16th Street, N.W.

Washington, D.C. 20006

Chairman

Jack L. Mickle, Ph.D., P.E.

Professor of Civil Engineering

Iowa State University

Ames, lA 50011

(515) 294-7627

Technical Observer

Felix Y. Yokel, Ph.D., P.E.

National Bureau of Standards

Washington, D.C. 20234
BIOGRAPHICAL SKETCHES I TASK FORCE MEMBERS

CLIFFORT W. .UlLQl'ISr

Mr. Ahlquist has 29 years of experience as a contractor Installing water

and sewer lines. He has been employed as a foreman and worked on projects in Minnesota, Pennsylvania and Washington, D.C. Metropolitan Area.

CARL F. GILL, SR.

Mr. Gill has 37 years experience and is a Master Mechanic in the Plumbing,

Heating and Air Conditioning Trades. He has also worked as a laborer and

crane truck driver. The majority of his work experience has been in the

Washington Metropolitan Area.

ROBERT L. MACK

Mr. Mack has 37 years experience as a construction laborer and foreman.

He is presently an instructor at the Francis L. Greenfield Institute,

Sterling, Virginia. The majority of his work experience has been in the

Washington Metropolitan Area.

JERRY MARTIN

Mr. Martin has 30 years of experience and is Director of Occupational

Safety and Health Training, Operating Engineers Local #3. He has been

employed as a Journeyman, Foreman, Superintendent and Equipment Manager.

His experiences include job assignments on transmission pipe lines, sewer lines, storm drains, pump stations, petroleum, oil, lubricant distribution pipe-lines, water main pipelines, gas main pipelines in North

Dakota, California, Maryland, Arkansas, Eniwetok Atoll, Franch Morocco,

Arabia, Spain, Greenland, Iceland, Alaska, Guam, Azores, Italy, Libya,

Liberia and Kuwait. He is a member of numerous Federal, State, Professional and National Safety Boards, Commissions and Societies.

CHARLES L. STOVER

Mr. Stover has 30 years experience and is the Safety Director, Operating

Engineers Local //77. He has worked as an Apprentice, Engineer, Steward

and Business Representative. His work in the Maryland, District of

Columbia and Virginia areas has included projects for sewer excavations,

natural gas stations, building construction, power house and disposal

plants

ROBERT E. WOOD

Mr. Wood has 19 years experience and is a Journeyman Plumber and Pipefitter. He has worked primarily as a foreman on jobs in Pennsylvania,

Delaware, Maryland, Alabama and Florida.

;

)

t

i

i

I

94
JACK L. MICKLE, CHAIRMAN

Dr. Mickle has been a registered engineer for 22 years and is a Professor

of Civil Engineering at Iowa State University. He has conducted numerous

research projects and teaches Soil Engineering.

JIM E. LAPPING, COORDINATOR

Mr. Lapping is Director, Safety and Occupational Health for the Building

and Construction Trades Dept., AFL-CIO. He has worked with the affiliated International Unions in developing and conducting Construction

Safety and Health Training for Union and Management leadership.

95
JOB ORGANIZATION

BID DOCUMENT

R.O.W. Job

Adequate right-of-way shall be provided for proper execution of the job.

Overall Design

The overall design shall provide for the safety of the worker.

Soil Conditions

Whatever information concerning soil conditions is available, need to

be included in the bidding documents.

Locate Utilities

The location of all utilities needs to be shown in the bid documents.

Medical Facilities

The location of the nearest hospital where a man may receive treatment.

First line supervisor needs to have this knowledge and responsibility.

Safety Program

Include as item in bid document.

PRE JOB CONFERENCE

Construction Procedures

Safety program shall be outlined. (Was incorporated in the bid

document .

)

Permits

Permits shall be required before any work begins.

Supervisory Personnel

I First line supervisors shall be trained in OSHA approved or equivalent

safety training.

Medical Facilities

See under Bid Document - Medical Facilities

96
Safety Program

The Supervisor shall provide for weekly safety meetings for all workmen.

Good housekeeping on the job site shall be mandatory. Nearest Rescue

Squad and how to contact.

JOB SITE WORK PROCEDURES

Equipment Standards

Equipment and tools shall be adquate for the job and properly maintained.

Job Execution

The supervisor shall be knowledgeable in all facets of the work. There

shall be proper posting of OSHA Regulations.

Working Alone

No one working along - no workmen shall be permitted in a trench without a topman. This is important, it cannot be overemphasized. (Equipment operators cannot be considered topmen) . There shall be sufficient

manpower to properly do the job.

97
Orientation to the Job Site

Safety Program: the following need to be emphasized in the safety

program:

1. Blind side equipment

2. One man gives signals

3. Proper rigging (shackle or closed hook)

4. Pressure testing the pipe

5. How much weight should a man lift

6. Safety guard rails around holes

7. Inspection and maintenance of equipment (and recordkeeping)

8. Equipment too close to ditch

9. Job housekeeping

10. Weather conditions

11. Efficient and safe utilization of job site hand tools

12. Use of gases in confined spaces

13. Fumes entering work space

14. Exposure to radioactive minerals

15. Pressure hazards (air locks, etc.)

16. Certified divers where required
SPECIFIC RECOMMENDATIONS

OSHA TABLE P-2

OSHA TABLE P-2 is impractical because :

1. The braces are too closely spaced, the result is:

a. It is extremely difficult and hazardous to install pipes.

b. Laborers can't function (8 feet spacing is necessary)

c. It is difficult for any digging operation except small

hydraulic clam shells.

2. People are unfamiliar with the table.

3. The table is very difficult to Interpret.

OSHA TABLE P-2 may be improved by :

1. Increasing the size of stringers and braces; probable minimum

should be 10" x 10".

2. Increase spacing of braces to 16 feet with a temporary brace to be

used in the center when driving sheeting and grading for pipe.

3. Do not use small timbers; they will "pop".

4. Do not recommend 3" x 4" uprights.

5. Use full 2" thickness sheeting to 12 feet and full 3" thickness

sheeting for greater depths.

6. The greatest pressure on shoring in normal trenching depths appears

to be at the base of the shoring.

7. Provide for temporary bracing just beyond the ends of each section

of pipe as it is being installed.

8. See Figures A-9 and A-10.

CONSTRUCTION DESIGN

Adequate right-of-way. A national system (such as Underground Services

Alert, U.S.A.) for locating utilities is necessary.

ALTERNATIVE PROCEDURES

Some procedure needs to be established to provide for innovation in

procedures and equipment.

99
PERMITS - APPROVED PLANS

SOIL IDENTIFICATION

How different soils respond to disturbance.

1. Good Soils will break up uniformly when excavated.

2. Soils which required watching have the tendency to come out of the

excavation in globs.

3. Wet clays are the most critical and treacherous.

4. Moist, sandy conditions are very treacherous.

CONSTRUCTION PROCEDURES

Sloping - See figures A-1 and A-2.

Trenching Widths - See figures A-5 and A-6.

Minimum Depth

Free Board (Pig Trough) - See figure A-7.

Surcharge (super-imposed loads, soil banks) - See figure A-8 and A-9

Skeleton Bracing - See figure A-3.

Clear distance from spoil pile to edge of trench - See figure A-8.

Ladders tied off - ladders shall be properly secured and extend a minimum of 3 feet above the surface of the ground. The ladders need

to be in place in the trench when workmen are in the trench.

PRE-ASSEMBLED EQUIPMENT

Braces and Jacks

Hydraulic or screw jacks should not be extended beyond a practical

working limit.

Ladder (How Judged)

Ladders must meet OSHA requirements.

Design of Shield

Use realistic sketch of a shield for examples. See Figure A-11. The

shield may be made of steel or its equvalent.

100
Protection of Public

National Color Code

A national uniform color code shall be adopted for public utilities.

Unattended Excavation

Excavations should not be left unattended without barricades.

Job Site Visitors

No children or unauthorized personnel should be permitted on the job

site

.

Personal Dress and Behavior

Engineered Workspace

Emphasize the engineering of a safe workspace in addition to designing

personal protective equipment. The first priority would be to engineer

out the problem.

Clothing and Equipment

The workman shall wear proper clothing and proper personal protective

equipment (conforming).

Personal Behavior

Proper personal behavior (no horseplay)

.

Standards

There is a Need For:

1. Uniform national standards

2. A proper standard reporting form

3. Organization of standards

4. Distribution
Training, Examinations and Licensing

There is a Need For:

1. Mandatory training (approved courses), for first line supervisors.

2. There shall be mandatory First Ald-CPR Training for supervisors.

3. Employee education and training needs to be implemented.

4. OSHA Safety: inspectors need training.

5. There needs to be standard criteria to evaluate inspectors competence.

102
SLOPING

Suitable

For

:

Not Recommended

For: Recommended for

Most Conditions

Probably Not

Necessary for

Worker Safety

A-1

103
SLOPING SIDED DITCH WITH SUBDITCH

WITH VERTICAL WALLS - IN LIEU SHORING

minimum of 30" or OD + 2"

A

104
SKELETON BRACING
TIGHT SHEETING

For use in trenches up to 7 feet deep

A

106
MINIMUM TRENCH WIDTH

///

A minimum of 12" on each side of pip®

workman to stand

A5

107
A-6

108

Depth
!;

!

'!

109
A

110
2 300 pounds /ft

uniform surcharge

A-9

111
112
Excavating and

Trenching Oparations

Safe Work Practices Series

U.S. Department of Labor

Occupational Safety and

Health Administration July 1975 OSHA 2226

Figure 3.

This is inappropriate as an example; does not look like

any existing equipment

A-11

113
. ‘ liL. ’* '

t

>3 • jn)C* • »

*.vi< 4t^

\

\

t

'. “t* jtf iSf U < Me ‘T bnasnit3VflS>x3

9«oiJais.siO S

'>» [3

5vc np

I bc«<t« Wiii

I ^f* " «a- . I ya Bi (

' .w w a" ‘ ^ 'i'i "iu.«y

,f'

..'

' ;

',

B5 - .: ,’4> ,

’

•so*.; »p DP* ifttiti w..;,

" ^

i:': ^ a«6S,/W«p'

'

ht»*< ,r^

*hi 4- !. Le^ J

• " * ,;• Aui.i ).'*“•« -i(ti '^'^

9

09 Ofi d3*l7qoT<l<3ffl4't

ttjlll iool 30fl 8»ob ;^li3^!AJf#

3n»«qli>iMf sni:a»tx» W
NBS*114A (REV. o-7e)

8. Performing Organ. Report No

U.S. DEPT. OF COMM. 1. PUBLICATION OR I^EPORT NO. BIBLIOGRAPHIC DATA

SHEET NBSIR 80-1988

4. TITLE AND SUBTITLE

%)

A Study of Work Practices Employed to Protect

Workers in Trenches

S. Publication Date March 1980

AUTHOR(S)

Jimmie Hinze and Nicholas J. Carino

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fSfreer, City, State, ZIP) 13 . Type of Report & Period Covered Department of Labor

Occupational Safety and Health Administration

Washington, D.C.

15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

IS. ABSTRACT (A 200^word or teas factual aummary of moat ai^ni ficatU information. If documant incfudea a aignificant bibtiography or

titaratura aurvay, mention it hare.)

Results of a field study of trenching practices, safety related problems

in trenching, and the effect of the Occupational Health and Safety Administration

(OSHA) regulations for excavation, trenching and shoring are presented. The data

were gathered from over 100 interviews with contractors and foremen in various

regions of the country and from the answers to questionnaires sent by contractors’

associations to their membership. The data indicate: 1) the technical aspects

of trenching work, 2) the industry’s opinion of the current OSHA regulations, and

3) factors affecting safety performance in trenching work.

17. KEY WORDS (s ix to twelve entries; a/p/ie6etical order; capitalize only the firat letter of the firat key word unteaa a proper name;

aaparated by aemicolona)

Construction safety; construction standards; excavation; safety regulations;

shoring; trenching.

18. AVAILABILITY Unlimited O Official Distribution. Do Hot Release to NTIS

[_ J Order From Sup. of Doc., U.S. Government Printing Office. Washington. DC

20402, SD Stock No. SN003-003-

Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

121

22. Price

$9.00

USCOMM-DC
'* Pj . ~.mt. i^«: Ji -i w>^ 88^x-oe Hi««rr 5

^S 4” ^ JD»:>01^ 03 b»^X<j«»S fc« 0±3o»Tl itow fo

9 «rf3xnr*t

»««wo3 fe«»«tf« * Hh^jl

oaXioO *t* oalorioi^t fuMt »«nXa »lii<|lt"^:

iqiiaowatI w OAanu* J(M*oitAH

.olMC-','- »am»M03 ^0 TMU^TRf^

5;

;A1« ft»V0

noXJ»t3*laSa*iAirf3l#s4. hm >^<>U8 X^noWmqoaT&Q^

^ M “ . 0.(1 «ttPi 8fltiftiiW

,b«ft>4tM fl »vnw<^ iSl*! fitt’’

< 310 -^*^.

-

'

i lHtlUBiioO' -ft. iMfl >

I ’-f ->b >

' ^|552j

\ut B»KHr<r»t» • ^ \v.^ 'V ^ /VI

b534X*» t3»U« ,**9X33»Tr^ snlrfoftwa io yfcw3« 0

j30JU«T^%itl»hA vi»^i.a bon /fjin^a XAfloi3A<p«>oO »d^ ^o:3o»n»

• )*h wft .H9a»9»n »-»^ aol-rerf* br» 8nW»09i3T= ,i»0X3«o»M0 lol

auAlwv rtl AAai*':©^ bw ei^iioeTittoo iJ3 j:v *woiim3fti OOX lOvo *joi1

< •t«o3 o*iJi?oo ijfit «n rflnaol 3«oyp 03 arswaou *«13 |«»

^3 twoo ada \

boB , •<i4UBXuj<ri MIfT (W<3 5o irotniqo «* y'j J«vl^ 0^ (S

~.i -«. » -«.. .«' .* <>-• »»••«- v«~w«

j«»i4 .1oi« Tl»lM inotasvM*. :.b:..bn«3« <rdl3M73.»3 !'<='*^

'““f

‘^rw|H|H| .g/rx40«iO3 J *aw‘^09“J

Viui

f4 Ao“.ir

tsoA^orraif-^

"i^Ai^rTmmrjBti

Wttn «l H>w oO .i»o<J»*HiUtO IfctonlO

nw.tl

f»/W »Hrrv

uin^MAjawu

30 ,«o%AiAt«tf ,#»«W0 iwrrrtia Vft(HWV»^c<M^ ^ S52"S''.wJ^^

fl

±2T
VV I