The coastline is a most hazardous place to develop. The sands, especially of the barrier islands, are constantly shifting and may be washed away with any large storm. Waves, winds, and flooding from these storms are also a regular danger. Even worse, the mean sea level is on the rise and forecast to increase up to 3 feet in the next 100 years. Sea level rise, of course, threatens to engulf much of the coastline. Despite all this, development is on the increase up and down both of our coasts, as this article in the Miami Herald notes.
Also as the article notes, this is likely to mean expensive measures to save this development. It is certainly likely in urban areas such as Miami and New York. However, what of the huge amounts of development occurring elsewhere along the coastline? It is not very likely that sea walls will be built along the entire East Coast. It would be far too costly. Instead, much of the area is likely to be abandoned. However, is this being taken into account when development is being planned or permitted? It seems quite unlikely, especially when developers are likely to walk away well before their construction will be threatened. Also, the only planning tools being used right now only take into account estimates of current risk based on past events, which will further encroach inland as time goes by. It seems that we are spending our money foolishly and that the coming generations will lose much due to the foolishness of our investments.
Tags: climate change, coastal, development
It is a bit late in the posting, but Reuters has a story about the low bids that have been coming in on construction projects funded by American Recovery and Reinvestment Act (ARRA) money. They are reporting that bids are coming in 30% below estimates. This is in keeping with observation by the Public Water Supply (PWS) section of the NC Department of Environment and Natural Resources (NCDENR). The section has been distributing ARRA funds for water projects across the state and bids are most definitely coming in low as a rule.
The article goes on worrying that contractors are bidding below cost to win the projects and will be unable to recover funds because of redistribution of funds. My understanding, however, is a bit different. The PWS funding promises are based on the original estimates. Even though contracts may come in lower, PWS is still liable for the same amount until the project is completed and all change orders have been dealt with. Therefore, so long as there is legitimate cause for a change order, there is still opportunity for contractors to recover costs. The only strings attached that I am aware of are that funding may be prorated according to the portion of work that has been contracted by the February 17, 2010 ARRA deadline and that no work will be compensated that has not been performed by February 17, 2012. As a result, the biggest concern is speed and not compensation.
Tags: ARRA, construction, Reuters, stimulus
Hydropower is coming to the Triangle. The Raleigh News & Observer is reporting that Jordan and Falls Lakes, the area’s primary sources of drinking water, are going to be retrofitted for hydroelectric power generation. They should generate enough power for 1,700 and 1,200 homes, respectively. The two projects will contribute to the 12.5% renewable power generation mandate for the year 2021.
Tags: civil engineering, dam, hydropower, Raleigh News & Observer
The Philadelphia Inquirer is reporting that their fair city is implementing a novel strategy to reduce their problems with combined sewer overflows. Instead of making the pipes and wastewater plants larger to handle the stormwater runoff, they are retrofitting Low Impact Development (LID) practices to reduce the runoff in developed areas. There are to be widespread installations of bioretention facilities, permeable pavement, green roofs, and other technologies. The plan will cost $1.6 billion, but it should end up saving money in the end.
Tags: civil engineering, LID, Low Impact Development, Philadelphia Inquirer, stormwater
“Meandering rivers are common on Earth and other planetary surfaces, yet the conditions necessary to maintain meandering channels are unclear. As a consequence, self – maintaining meandering channels with cutoffs have not been reproduced in the laboratory…” until now. Science Friday, a radio show on NPR, has just posted the following video of the first such model, which has been developed by UC Berkeley researchers.
“Experimental channels <like the one in the video above> are needed to explore mechanisms controlling migration rate, sinuosity, floodplain formation, and planform morphodynamics and to test theories for wavelength and bend propagation. Here we report an experiment in which meandering with near-constant width was maintained during repeated cutoff and regeneration of meander bends. We found that elevated bank strength (provided by alfalfa sprouts) relative to the cohesionless bed material and the blocking of troughs (chutes) in the lee of point bars via suspended sediment deposition were the necessary ingredients to successful meandering. Varying flood discharge was not necessary. Scaling analysis shows that the experimental meander migration was fast compared to most natural channels. This high migration rate caused nearly all of the bedload sediment to exchange laterally, such that bar growth was primarily dependent on bank sediment supplied from upstream lateral migration. The high migration rate may have contributed to the relatively low sinuosity of 1.19, and this suggests that to obtain much higher sinuosity experiments at this scale may have to be conducted for several years. Although patience is required to evolve them, these experimental channels offer the opportunity to explore several fundamental issues about river morphodynamics. Our results also suggest that sand supply may be an essential control in restoring self-maintaining, actively shifting gravel-bedded meanders.”
For the complete research article, see the Proceedings of the National Academy of Sciences.
Tags: civil engineering, fluvial geomorphology, geology, hydraulics, National Academy of Science, NPR, Science Friday, stream restoration, UC Berkeley, water
(Yonkers Historical Society) Yonkers, N.Y., diverted the Saw Mill River through a giant underground flume in the 1920s. Now, inspired by other cities’ efforts to “daylight” such waterways, Yonkers is trying to unbury the river and create a greenway along its banks.
The New York Times has a story about the popularity of restoring forgotten urban streams. These streams are forgotten because they have been piped and paved over, making them seem to be just another part of the storm drainage system. This was often done to hide the pollution that ran through urban streams prior to the various waste treatment measures that have become widespread. Restoration of these streams has become a worldwide phenomenon involving reaches in such varied locations as Seoul, New York, London, Los Angeles, San Antonio, and Vancouver. One might even count Rocky Branch, which runs through North Carolina State University and highlights the work of the Biological and Agricultural Engineering Department.
There are various reasons for this movement. The first is to bring a bit of nature to the city much as one might do with a park. It makes the city a friendlier place that attracts more visitors and provides a place for recreation. However, the reasons for restoration go deeper than that. For example, streams provide habitat. The streams in Vancouver used to provide spawning grounds for salmon. By providing habitat, we improve and augment the food chain, which will ultimately improve and augment our own food. Another example is the cleaning and filtering of runoff that is performed by floodplains. Many of the elements found in stormwater runoff are either themselves health hazards or are nutrients in such over-supply that can cause microbes to run wild; in turn causing their own problems. By removing these elements, the floodplain protects the stream habitat and downstream water supplies. Ultimately, we are all connected to and use these streams: to bathe in, drink from, and grow food (in the wild or via agriculture). It is heartening that so many places have seen the importance of using them wisely.
Tags: civil engineering, New York Times, restoration, stream
According to the New York Times, the White House Council on Environmental Quality (CEQ) is drafting new federal floodplain rules to be mandated by Executive Order. These rules are to be followed by the federal government and likely by anyone using federal money for a project. It seems that the federal government, like state departments of transportation, has been having trouble following the rules put forth by the FEMA National Flood Insurance Program (NFIP) and the White House would like have it lead by example. For this reason, these proposed rules are likely to exceed the minimums mandated by the NFIP. For example, critical infrastructure is not to be located in the 500-year floodplain unless no alternative is available. If development does occur in the 100-year floodplain, it is to occur in consultation with state and local officials; thus making it follow their rules should they prove more strict.
Tags: civil engineering, FEMA, floodplain, New York Times, planning
And now for some local news. The main source of drinking water in Raleigh, Falls Lake, has had some problems with nutrient levels and algal blooms. The Neuse River, on which Falls Lake is located, already has a set of rules to regulate nutrient levels in stormwater runoff. However, due to the sensitivity of the problems at Falls Lake, a combination of state and local officials in Wake County are pushing a plan for a speedier cleanup of the lake through the State Legislature. This has great potential to affect Durham County, however, as much of the pollution appears to originate there. The likely result would be an accelerated and expanded plan of retrofits to existing development to treat stormwater runoff. It is also a potential double whammy for Durham too, as Jordan Lake, to its south, is currently undergoing development of a similar plan. The difference for Durham, however, is that it uses Jordan Lake as a drinking water source.
Tags: civil engineering, Durham, Falls Lake, NCDENR, North Carolina, pollution, Raleigh, stormwater, The News & Observer, Wake County, water
This comes as no surprise to many engineers, but those interested in infrastructure are feeling quite a bit underwhelmed about the amount of stimulus money that has been allocated to the cause, according to the Wall Street Journal’s Private Equity Beat. The article mentions that $30 billion was allocated for infrastructure in the stimulus package, which certainly seems like a significant amount of money, but the need is calculated to be in the trillions of dollars in order to meet standards set by competing developed nations. In fact, from what I have experienced and heard, the stimulus money is being used in large part to make up for budget shortfalls in state and local governments. It seems clear that, in order to address our infrastructure issues, some other measure will have to be taken. Perhaps this is where the National Infrastructure Bank comes in?
Tags: ASCE, civil engineering, infrastructure, Wall Street Journal
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