C9.2 Excavation

Question 1

Methods to avoid excavation

Answer 1

micro tunnelling
directional drilling
impact moling
pipe bursting

Question 2

CDM reg 22

Answer 2

Steps to be taken to prevent danger to any person

protection from collapse
protection from material falling in
protection from people / equipment falling in
prevent surrounding ground being overloaded

Question 3

excavation hazards

Answer 3

collapse of sides
equipment / material falling in
people falling in
flooding
gases / explosion - methane build up
fumes -  contaminated ground
collapse of nearby structures / under mined foundations

Question 4

measures to support excavation sides

Answer 4

trench box
shoring
steel sheets / piles

Question 5

measures to prevent collapse of nearby structures

Answer 5

shoring / supports

Question 6

measures to prevent falling in

Answer 6

guard rails
lit at night
stop blocks / sleepers
covers over shallow trenches

Question 7

excavation inspection reports

Answer 7

by competent person
completed within 24 hrs
report kept on site
conduct weekly if no adverse event

Question 8

contents of excavation inspection report

Answer 8

name / address of person inspection was done for
location of work
description of work
date / time of inspection
details of any H&S issues
details of any action taken
details of further required action
name / position of person writing report

Question 9

underground services

Answer 9

gas
electric
sewerage
other pipes - oil, chemical, petrol
fibre optics

Question 10

excavation SSW

Answer 10

planning
avoidance of services
protection / support of services
material handling
waste
public protection

Question 11

how to detect services

Answer 11

plans - may be out of date
detection devices
CAT scanner (cable avoidance tool)
ground penetrating radar

Question 12

measures to protect underground services

Answer 12

detect
re-route
support
hand dig within 0.5 metres with insulated hand tools
fencing
hung up
labelled

Question 13

mechanisms for excavation collapse

Answer 13

loose soil
water logged
heavy plant too close
vehicles cause vibration
inadequate support
excavation below level of shoring

Question 14

mechanisms for falls of people / items into excavations

Answer 14

materials too close to edge
excavation too close to building
excavation edge not clear
no barriers
no lighting
poor position / lack of ladders
unsuitable / no vehicle ramps
no stop blocks
vehicles too close

Question 15

measures to control water ingress

Answer 15

pumps
advice from EA
if within 10 metres, Consent for Works Affecting Watercourses from EA

Question 16

CDM Reg 31

Answer 16

start of shift inspections by competent person
inspections after any event that might affect stability of excavation
inspections after any material fall

no work if adverse inspection findings until fixed

Question 17

considerations ref shoring

Answer 17

subsoil - if wet, use metal sheets
duration of works - trench / drag box for short duration
type of work - trench / drag box for pipe work
minimise length of excavation trench
flooding risk
excavation depth
number of people in excavation hole at any time

Question 18

360 degree excavator hazards

Answer 18

impact with pedestrian / vehicle from swinging boom 
impact from bucket
contents falling from bucket
hydraulics under pressure
overturn
contact with overhead power lines

Question 19

360 degree excavator control measures

Answer 19

trained users
not overloading
maintenance / inspection
pedestrian segregation
signage
driver visibility aids - cameras / mirrors
high viz
roll over & cab impact protection 
seatbelts

Question 20

contents of a permit to dig form

Answer 20

principal contractor name
sub contractor name
permit number
date
location
size /depth
service plans yes/no
cable locating equipment yes/no
services marked out yes/no
trial holes needed yes/no
precautions for overhead power yes/no
sketch / copy of plans
date / time of excavation
signed by issuer and receiver