BIG MAN RETIREMENT STUDY DECK Flashcards
OH NO GROUND FAILURE 1 HAS HAPPENED WHAT IS THE ACTION LIST (IMMEDIATE ACTION PLAN)?
- stop work
- headcount
-secure entire site area including unaffected zones that may still be at risk - contact worksafe in accordance with section 68 of workers compensation act
- document the scene (photos, statements, site survey, report)
- hold a site coordination meeting with (geotech, super, safety buddy)
- create task force to create remediation plan
- contact farmer and other stakeholders that may be impacted
Ground #1 - WHAT IS THE SHORT TERM PLAN
- place temporary shoring or berms along toe of failure to stabilize wall
- determine cause of failure (borehole or test pits, reviewing original borehole data)
- determine liability for failure
(insurance, owner, contractor / DB entity, geotech) - plan to leave failed existing materials and walls in place to finish preload duration
- install dewatering and surface drainage
- monitoring systems for ground water or settlement
- execute remediation plan
ground failure #1 WHAT IS THE LONG TERM PLAN
- quantify damages
- sum up incurred costs resulting
- prepare a claim
ground failure #1 and #2 - what are some options for recovering costs?
- file a claim against the owner
- identify an underlying cause attributed to another party (inadequate design, poor workmanship for construction, oversight or lack of due diligence on the part of others)
- file a ground failure claim with insurance (not typical)
ground failure #1 and #2 - who is liable? (who generally pays)
Liability typically rests with owner for unforeseen ground failure because:
1) No fault if all parties did their due diligence
2) More thorough geotechnical investigations could have always been done
(This is a risk reward that the owner takes on when pricing geotechnical work)
In rare cases, the owner or contractor may have taken out a Ground Failure insurance policy
1) Not typical, although was the case for this incident
2) Likely insurance company would seek to recover costs if due diligence wasn’t followed
3) Insurance company may still attempt repayment through legal action
ground failure #1 and #2 - global vs internal failure
- Failure area: Internal failure is limited to the wall, Global is the entire area
- fault: Wall design to blame for internal, soil conditions for global
- Type: Wall fails due to shear or overturning moment, global fails in circular slip plane
ground failure #1 and #2 - risk distribution
1) Proper design, construction, following of specifications and regulations
2) Based on borehole information provided
3) Proper due diligence by general contractor, designer, and construction
a. Due to uncertainty in geotechnical
b. Claim against owner as they retain liability for unforeseen events
4) If errors in construction or design
a. Partial or full liability shifts to the responsible party
ground failure #2 - what are the costs incurred
1) Lost profit due to delays (hard to prove on linear work schedule projects)
2) Repair to impacted property such as fences, ground thrust, or damaged culverts
3) Stabilization costs, such as dewatering or soil berms
4) Remediation costs, general labour and material costs to restore failed structure
5) Geotechnical investigation work, such as test pits, reports, boreholes, expertise
6) Survey Costs to document scene and quantify impact
7) Improvement Costs, such as over excavation or soil densification
8) Other costs such as fines, additional staffing, or hours for meetings, consulting fees
Westgate - Describe the details and the significance of the three geofab tests conducted
Contact test with no restraint (GOOD):
-GEOFAB held back significant portion of soil particles and was able to maintain head difference of 218 cm
Contact test with vertical restraint (GOOD):
-GEOFAB filter allowed slight passage of fines and filter was able to maintain a head difference of at least 210 cm
Unconfined Test (BAD):
-1 cm gap present, upward flowing water liquefied soil and a significant portion of particles passed through the GEOFAB
Westgate - what are the causes of failure?
a) Drainage pipe location
used to control level of water table below road, placed at springline instead of crown
b) GEOFAB Contact Condition
3 tests, unconfined test, no vertical restraint, vertical restraint, (unconfined FAILED)
c) Poor Supervision of Construction
bros stopped inspecting due to CoSt, smith and associates said see ya to GE inspectors
Westgate - What’s the relevance of the GEOFAB information given?
GEOFAB is relevant in making two recommendations:
1. Criteria available to Lisa on which she could have based her recommendations regarding GEOFAB
2. The actual performance of the GEOFAB as a soil filter for the soil encountered at the failure sites
Westgate - Who is at fault and why?
LISA IS AT FAULT BY 100% STUPID BITCH FAG
-should have insisted on adequate data
-even if contractor appears to have experience, she needed to provide clear, detailed written instructions to insure that proper installation techniques were followed
-should have insisted on inspecting all sections of trench
Westgate - what lessons are to be learned?
-diary should be kept
-log all important telephone conversations
-don’t give technical advice over the phone
-confirmation and clarification of decisions and agreements in writing
-good communication essential
-explain why you are requiring details to be followed
Progress Curves
Cumulative estimated job costs VS construction time
a) One Early Start Curve
b) One Late Start Curve
Total Cost & Budgeted cost Plotted Monthly
Cost Envelop is created from present to end of job
Earned Value Management System (EVMS)
Compared the physical work accomplished to date with the actual cost expenditure and planned work
yet to be accomplished. This 3-Dimensional comparison determines the earned value on a project and
forms the basis for a more accurate projection of final project cost.
Benefits of earned value management system
An Earned Value Management System combines the actual cost of work completed with the planned
value of that work to generate a projection and determine whether a project is on track and on budget.
This provides project managers with a more accurate and comprehensive view of the project’s progress
over using a simple progress curve, which only shows the amount of work completed over time.
The Three Variables BCWP, BCWS, and ACWP
Budgeted Cost of Work Performed (BCWP)
Cumulative budgeted value of all work activities performed to date.
Budget Cost of Work Scheduled (BCWS)
Cumulative planned value of all the work activities to be accomplished in the baseline
schedule to date.
Actual Cost of Work Performed (ACWP)
Cumulative cost for work completed to date OR current cost of work
Cost Variance (CV)
CV = BCWP - ACWP
Schedule Variance (S)
SV = BCWP - BCWS
Cost Performance Index (CPI)
CPI = BCWP / ACWP
Schedule Performance Index (SPI)
SPI = BCWP / BCWS
CPI of 0.8 Means
20% Cost overrun (only 80 cents of every dollar value achieved)
SPI of 1.2 Means
Schedule performance Index
120% work done per budgeted dollar
The Three Variables BAC, EAC, and TCPI
Budget at Completion BAC
Estimate at Completion EAC
Total Completed Performance Index TCPI
EAC1 =
ACWP + (BAC – BCWP) / CPI
EAC2 =
ACWP + (BAC – BCWP) / (CPI * SPI)
TCPI =
(BAC – BCWP) / (EAC – ACWP)
How many trenches were used? Which systems were being replaced?
5 trenches for storm and sanitary pipe replacements
what were type material types/sizes of the new pipes?
For Storm - 300mm to 525mm reinforced concrete pipes
For Sanitary - 150mm vitrified clay pipes
What were the soil conditions?
Stiff native soil and rocks
What were the reasons for the pipe failures?
- Insufficient Bedding materials
- Inadequate design (design error) considerations for trench widths
- cracks in the pipes may lead to washout and bending failure in other locations
Elaborate on the insufficient bedding material failure
-doesn’t provide adequate uniform support
-capacity could be increased by more than double (from 1.1 to 2.5)
-May have contributed to uneven settlement issues and bending failure
-importance of bedding not conveyed to construction team
Elaborate on the inadequate design of the trench width
-If trench widths have been specified, more reliable calculations could be done
-Pipe spacing not specified
Pipes too close may have imposed unexpected load distributions on pipes below beside
Too much additional load may have led to exceeding cracking limit
-Crushing failure of pipes indicate cracking load was exceeded
-Bending failure of pipes due to unequal load distributions
-Proper construction techniques used according to experts retained by MHLP
Cracks in the pipe may have led to washouts and bending failures in other locations
-Washout failure of pipes due to crushing
-Removal of support, and increased bending in shallower areas
What was the issue with the drawings?
-Pipe elevations shown
-location of pipe in trenches not clear
-trench widths not identified
-physical limitations on widths in some locations
How does failure differ in deep pipes vs shallow pipes
Deep pipes - longitudinal cracks from crushing
Shallow pipes - transverse cracks from bending
What are some solutions to avoid pipe failure?
-designers should clearly define the pipe installation and trench specifications on the construction drawings. If the drawings are unclear, the contractor should clarify the information with the designer
-The designer should ensure that the trench is widen enough for compaction equipment to fit into the trench.
-contractor should use jumper jack to compact trench fill
-compact in lifts
What are some factors to consider when replacing equipment?
- Purchase Price and Leasing Costs
- Salvage Value
- Cumulative Operating Hours
- Ownership Cost
- Operating Cost
How to save money on equipment costs?
- Charge equipment rental rates that cover maintenance and operational costs
- Equipment accounting showing cumulative record of earnings and expenses
- Charge as a rental unit to account
- Replace when operational costs exceed equipment earnings
- Track equipment working, idle, and repair time
What is a project cost system?
Is a method of managing the costs associated with a project
What does a project cost system involve?
- establishing a budget for the project
- tracking and controlling costs as the project progresses
- ensuring that the project is completed within its allocated budget
What tools and techniques are used in project cost systems?
- cost estimation,
- cost planning,
- cost control, and
- cost forecasting
Why is a project cost system important in project management?
- Helps to ensure that the
project is completed on time and within budget - for evaluating the financial
performance of the project - making decisions about future projects
What was lacking in the NBCC prior to the arena collapses in 1959?
Little info recorded in Canada on snow loading on arch-shaped structures.
NBCC 1953 to 1960 lacked…
provisions in selecting uniform and non-uniform snow loads on arch-structures
1965 NBCC changes and issues
snow load distributions used in USSR.
Not directly applicable in Canada. Often experience one side completely clear.
NBCC 1970 and 1975 changes
One-sided loading (1970 to 1975 the same)
Issues discovered after 1975 Code
Only considered flat, long-span arches.
Steeper, shorter-span arch structures more common in Canada.
1977 NBCC changes
Based on snow-load study in the Ottawa region:
- Provisions for uniform snow loads
- Slope reduction factors
- New distributions for nonuniform snow loads
- considering snow drift
1980 NBCC changes
provided modifications to the distribution of snow loads on arch structures
1985 NBCC changes
- increased the unit weight of snow by 1.9%
- simplifications to examine unbalanced loading on arches
- specified loading due to snow accumulation (formula)
- snow load factor due to tests in Canada
- wind exposure factor
1990 NBCC changes
- increase unit weight of snow (2.4 to 3.0)
- Lowering wind exposure factor (0.75 to 0.5) for exposed roofs north of tree line
- Revised design snow loading formula (separating snow and rain loads)
–> assumes snow would drift due to wind loads but not rain
