Can I ask a favor of you? If you enjoy my blog, please take a moment to vote for it in the “Best Construction Blog” competition. The competition is by Mark Buckson, of Construction Marketing Ideas.
To vote, click here and select “Construction Law in North Carolina” (this blog). You also have the opportunity to vote for many other fine construction blogs at the same time, including some blogs you will recognize from my blogroll such as those by Chris Hill, Tim Hughes, and Ryan Bowers. You can vote for them or the other fine blogs there also, but you must should might consider voting for me.
Thanks in advance!
PS: To those worried about the legality of my “get out the vote” campgain, rest assured that Mark encourages everyone to campaign for votes!
The Chief Counsel’s Report on the BP Deepwater Horizon Oil Spill and Offshore Drilling has been released. Following on the heals of the January National Commission report to the President, the Chief Counsel’s report “provides damning evidence that preventable engineering and management mistakes—rather than mechanical failings—were the primary cause of the Deepwater Horizon rig explosion last spring,” notes ENR’s Pam Hunter.
Among the Technical Findings, the Report states that the root cause of the failure was that the cement that BP and Halliburton pumped to the bottom of the well did not seal off hydrocarbons in the formation. The report acknowledges several factors which may have increased the risk of cement failure, including:
- drilling complications forced engineers to plan a finesse cement job that called for, among other things, a low overall volume of cement.
- the cement slurry itself was poorly designed—some of Halliburton‘s own internal tests showed that the design was unstable, and subsequent testing by the Chief Counsel‘s team raised further concerns.
- BP‘s temporary abandonment procedures—finalized only at the last minute—called for rig personnel to severely underbalance the well before installing any additional barriers to back up the cement job.
Among the Management Findings, the Report states:
- BP did not adequately identify or address risks created by last-minute changes to well design and procedures. BP changed its plans repeatedly and up to the very last minute, sometimes causing confusion and frustration among BP employees and rig personnel.
- Halliburton appears to have done little to supervise the work of its key cementing personnel and does not appear to have meaningfully reviewed data that should have prompted it to redesign the Macondo cement slurry.
- Transocean did not adequately train its employees in emergency procedures and kick detection, and did not inform them of crucial lessons learned from a similar and recent near-miss drilling incident.
Legal Status? The lawsuits that will be flowing (pardon the pun) from this disaster will be extreme. Expect to see possible class action certifications requested for some of those that were suffered damages. In any lawsuit related to the spill, the report by the Chief Counsel will, undoubtedly, be Exhibit A.
Photo credit: Richard Sullivan, via Wikimedia/Creative Commons license.
Incredible feets of engineering are being planned for at the $1 billion-dollar Bayonne Bridge height raising project, a project of the Port Authority of New York and New Jersey. Engineers plan to raise the road from 151 to 215 feet above the Kill van Kull while simultaneously keeping the bridge open to traffic, a measure some are calling “a Herculean feat of engineering and construction.” The project is required to accommodate larger container ships (especially those arriving after the widening of the Panama Canal in 2014) to ensure continued viability of the port industry, and raising of the roadbed is the quickest and cheapest solution to the clearance issue.
“It’s truly an exciting engineering project, by all means,” said Peter Zipf, the Port Authority’s chief engineer. “It’s a completely challenging project, and that’s an engineer’s delight. It’s coming up with a regional solution to a regional need.” As an engineering precedent, Zipf said the Bayonne project will be the first time a replacement roadbed is constructed above the old one, with traffic remaining open, before the original structure is removed.
According to nj.com, during construction, the two inner lanes will be closed to traffic and used as a staging area where a crane will likely be used to hoist a series of 84-foot-wide girders into place, forming the steel structure underpinning the new roadway. Like the original, the new roadbed will be suspended by steel cables from the bridge’s original 79-year-old arch. The two existing outer lanes will remain open, shielded from the work overhead, providing one traffic lane in each direction. To rise to the level of the higher roadbed, Zipf said the bridge approaches will be made slightly steeper and longer, constructed in a similar method from staging areas on the original approaches.
About the Bridge
When the $13 million Bayonne Bridge opened on November 15, 1931, at 1,675 feet it had become the longest steel-arch bridge in the world, an honor it held for the next 45 years.
Thoughts on the engineering task ahead of them in maintaining traffic while raising the bridge? Thoughts on possible legal implications should the project not go as planned? Sign up for email delivery of the Blog’s posts to your inbox to learn the latest news concerning architects, engineers, designers, and other construction professionals.
Photo credits: Map via Wikipedia/Creative Commons License; Plan sketch via Frank Cecala & Andre Malok/The Star Ledger.
Following on last week’s story about green roofs, including one which collapsed under a weight of snow and ice, engineers speaking to the ENR have stated that Codes are adequate, but that they may need to be adjusted in certain situations:
[E]ngineer sources for this article say existing building codes are adequate if designers allow for a factor of safety. But Levy [Matthys Levy, chairman emeritus at Manhattan-based Weidlinger Associates] recommends designers make proper allowances for snow accumulation such as when designing roof structures near parapet walls, especially those that are four feet or higher.
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Multi-level roofs with steps instead of roof flashing can also be problematic with snow accumulation on a first-story portion, for instance, piling up against the second story, Levy says. “It’s best to avoid stepped designs unless you design for them,” he says. While an average of 40 psf may be adequate for designing most of a roof, designers should allow 60 psf to 80 psf for the parapet wall, he says. And mountainous regions may require twice as much strength, he says.
Garrick Goldenberg, professor of structural engineering at Wentworth Institute of Technology in Boston and chief structural engineer at Chappel Engineering Associates in Marlboro, Mass., said that while state building codes address snow drifts with requirements for the shape and slope of a roof, this year’s record snowfalls and ice accumulation with little thawing has led to a greater number of collapses. In sampling snow at Chappel Engineering in early February, Goldenberg says his group found that even two feet of freshly fallen snow or more totaling 16 to 20 lb/sf was not a danger to buildings. On average, people assume fresh fallen snow produces eight pounds of pressure on a roof per square foot.
However, invisible loads caused by accumulation of ice have been a serious problem since ice weighs 7.5 to 8 times more per cu ft than snow. “In many cases, even before reaching two-foot snow loads, we were in excess of 30 pounds because of the ice,” he claims.
For more, go to the ENR full story: Ice, Snow Take Toll on Northeast Roofs, But Engineers Say Codes Are Adequate.
What are your thoughts about current Codes, in light of the many collapses in the Northeast and Midwest? Legally, does designing to Code, but failing to take into account likely weather events, make your design deficient? I’ll post some of my thoughts in a subsequent post, but share yours below.
Photo: “Deck roof collapse“ by Derek K. Miller via Creative Commons license/Flickr
Two commercial “green” roofs have been in the news this week. One involves a collapse; one involves energy savings.
Green Roof Collapse
The green roof at the Aquascape, Inc. warehouse in Illinois collapsed over the weekend, likely due to melting snow and ice. A 50 foot wide section of th 256,000-square-foot roof (allegedly the largest sloping green roof in North America) collapsed on Sunday, although no injuries were reported. A team of structural engineers from the building’s design firm is investigating the cause. As noted in a company press release, St. Charles, IL, where Aquascape Inc’s head office is located, had been recently hit with a major snow storm where 20.6 inches of snow had fallen in less than 24 hours, followed by above freezing temperatures causing a quick thaw. An ice damn at the base is suspected to have backed the water up over the parking structure causing its collapse.
Solar Roof goes “live”
While Aquascape’s engineers are investigating their roof collapse, there is some good green roof news closer to home. Raleigh-based marble company David Allen Company has recently “flipped the switch” on a photovoltaic solar energy facility that it claims is one of the largest rooftop photovoltaic systems in the Triangle, with 700 solar modules covering 23,000 square feet of the rooftop of the company’s warehouse. The company hopes to offset at least 35% of its current electrical costs, and sell energy to Progress Energy as well, according to Triangle Business Journal. Check out these photos of the installation by Peak Solar Investors, LLC.
Legal Implications related to Roof Design?
Both of these roofs bring up legal issues. Was the Aquascape green roof designed appropriately to accommodate loads in a winter climate?
With so many roof collapses this winter (including, of course, the Minneapolis metrodome) , is there, or should there be, a duty on the building’s owner/maintenance crew to proactively remove snow accumulations?
For new solar roofs, such as at David Allen Company, who assumes the risk if the expected cost savings are not realized?
Based on the sheer number of roof collapses this winter, and the number of green projects growing steadily, there is sure to be some litigation addressing at least some of these issues in the near future. Stay tuned.