MUSKRAT'S "DOOZY" OF A PROBLEM

Guest Post by James L. Gordon

What else can go wrong – this one is a doozy!

There are 3 synchronous condensers (SD) at the Soldiers Pond substation on the Avalon         

Peninsula, the down-power end of the DC transmission line.

NORTH SPUR: JIM GORDON TRIES AGAIN TO GET SIOBHAN COADY'S ATTENTION

Dr. Stig Bernander

Editor's Note: Canadian Hydro Engineer, Jim Gordon has worked hard to get successive Ministers of Natural Resources, including more recently Siobhan Coady, to take seriously the geotechnical analysis conducted by Swedish scientists Dr. Stig Bernander and Dr. Lennart Elfgren in relation to the North Spur, but without success. 

The Spur is a natural formation which forms part of the dam structure for the Muskrat Falls project. The feature contains clays defined by experts as "sensitive" because under certain circumstances they have the capacity to liquefy and to collapse. The issue is increasingly urgent because Nalcor, in a matter of days, will begin filling the Muskrat reservoir to the 39 meter level. 

JIM GORDON'S FINAL COMMENTS ON THE NORTH SPUR

THE NORTH SPUR – MY FINAL COMMENTS
Guest Post by James L. Gordon P.Eng.(Retired)

Way back in 2014, my interest in the North Spur started when I read a short book by Cabot Martin titled “Muskrat Madness”. It concentrated on the questionable stability of a natural side dam called the North Spur which contained layers of sandy silt and sensitive clay. I emailed Cabot, a member of the 2041 committee, on August 27th commenting on his book, and have commented several times on the Uncle Gnarley blog on the North Spur safety. NALCOR describes the Spur as -

The north spur forms a natural earthfill dam, with a crest elevation of about 60 m, and about one km long, which connects the rock knoll to the north bank of the valley……. The crest width varies from about 1,000 m at its north end to about 70m at its south end where it has been narrowed by erosion and landslide activity in the past. The head across the spur is presently 16 m from river level upstream to downstream. The impounding of the reservoir to El. 39 m will increase the hydraulic head across the spur to 36 m and stabilization measures are then necessary to ensure its long-term stability under both normal and extreme water levels. The soils forming the spur consist of a complex interbedded sequence of relatively low permeability silty sands and sands, and sensitive marine clays.

COADY WRONG ABOUT NORTH SPUR REVIEW, SAYS SENIOR ENGINEER

Guest Post by James L. Gordon, P. Eng. (Ret’d)

THE NORTH SPUR DESIGN HAS NOT BEEN REVIEWED BY

MULTIPLE GEOSCIENCE ENGINEERS!

The presence of quick clay and soft sensitive clay has been known ever since the Spur was first investigated in 1965. Several consulting engineering companies have looked at the Spur and issued reports on their investigations. Many have proposed solutions to stabilize the Spur.

However, all this work can be regarded as preliminary since the geotechnical investigations were incomplete. None of the proposed solutions were “approved for construction”, nor intended to be. They were the first attempts to find a suitable solution to the instability demonstrated by the many landslides in the vicinity of the Spur, and on the Spur.

SNC have undertaken further geotechnical tests and have developed a design which has been “approved for construction”, and has been built.

However, the design has not been reviewed by senior geotechnical engineers with experience in sensitive and quick clay, contrary to the assertions of Natural Resources Minister Siobhan Coady.

ENGINEERS' COMPETENCE TO PRACTICE QUESTIONED

Guest Post By James L. Gordon, P. Eng. (Ret'd) 

On May 1^st, I read with mounting astonishment the aDB Engineering report dated April 20, 2017, on their investigations into the causes of the collapse, which occurred on 29^th May, 2016.

The level of incompetence described in the report is so widespread that it brings into question the integrity of all other structures in the development. All staff, from carpenters to engineers are included within the ranks of the incompetent. The sub-standard construction was clearly visible to all, but nothing was done to rectify the errors.

The collapse occurred in the lower portion of the draft tube as shown on the following Figure1, copied from Figure 2 in the aDb report. In this area, the water passage changes from a vertical expanding cone to an almost horizontal expanding rectangle as shown in Figure 2. It is the most complex double-curved shape in the project and very difficult to build.

For small turbines, the shape is formed in timber, with an east coast shipwright engaged as the carpenter foreman. A shipwright carpenter is the only person capable of cutting and shaping the timber to the required complex shape.

MUSKRAT: HYDRO ENGINEER NOTES QUALITY CONTROL PROBLEMS

Guest Post by James L. Gordon, P.Eng. (Retired)

There have been two recent incidents at Muskrat which indicate that there is an inadequate quality control process at the construction site. 

The first was the announcement by Andritz, the spillway gate contractor, that they were suing NALCOR and Astaldi. The contractor cited changes in the schedule by NALCOR and errors by Astaldi in their work on the spillway concrete, as stated on the CBC news on May 25. The second, and far more serious incident, was the collapse of a concrete form in the powerhouse on May 30.

To comment on the Andritz situation first: Andritz base their claim on two factors, the delay in the schedule, and defective work by Astaldi. Their claim states “However, by the first half of 2014 it was obvious to Muskrat and Andritz that the civil works performed by Astaldi were delayed,". The construction delays are well known, but their impact on Andritz required “(an) aggressive and in Andritz's view, likely unattainable on Muskrat's stated budget."

ASTALDI CONTRACT "A RECIPE FOR DISASTER" AMONG CONCERNS OF TOP HYDRO ENGINEER

Guest Post by James L. Gordon, P. Eng.

When Astaldi demolished the half-built dome, I just could not understand the reason for their decision. Now I know!

All hydro projects built in Northern Canada are constructed with heated and illuminated, insulated fabric enclosures covering all concrete work, sometimes with a small high-speed crane at the top to transport concrete buckets and skips of re-bar. The enclosures provide an excellent 24-hour, 7 days per week work environment, greatly increasing productivity.

With the release of the EY interim report, they mentioned that remuneration for the work undertaken is based on man-hours. Page 9, part 5.8, states –“However, the payment mechanism is based on person-hours expended rather than m3 of concrete poured.” This is a recipe for disaster, since the contractor, Astaldi, can increase remuneration and hence profit, by increasing staff.

WHY THE NORTH SPUR DAM DESIGN NEEDS REVIEW (A PRIMER)

A non-technical primer on dam design.

Or why the North Spur dam design needs to be reviewed.

Guest Post by Jim Gordon. P. Eng. (Retired)

          In view of the controversy over the North Spur dam design, I have prepared the following brief review of dam design over the ages, to show why the North Spur dam design needs to be reviewed.

Dams have been built for more than 5,000 years, with the first recorded being the Jawa dam in Jordan built about 3,000 BC. Another was the Sadd al-Kafara dam near Cairo, built about 2,850BC. It had a height of 11m and a crest length of 81m. 

The highest ancient dam was built by the Romans in the first century at Subiaco, near Rome, having a height of 50m.