Tag Archives: stormwater

blue-green roofs in the Netherlands

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Blue-green roofs seem like a good idea.

Beautiful green roofs have popped up all over the world: specially selected plants growing on structures specially designed to manage the extra weight of biomass. Amsterdam has taken that one step further with blue-green roofs, specially designed to capture rainwater. One project, the Resilience Network of Smart Innovative Climate-Adapative Rooftops, or RESILIO, has covered over 100,000 square feet of roofs in Amsterdam, including 86,000 square feet on social housing complexes. Citywide, the blue-green roof coverage is even bigger and growing, currently estimated at over 500,000 square feet.

Wired

Making this widespread would be great, because buildings represent a large proportion of impervious surfaces in urban areas, and in the type of dense, walkable urban areas some of us think are best for people and the environment overall, there is not always enough room to deal with runoff from rooftops when it gets to the ground. So dealing with it on rooftops is great.

But alas…despite the impression that this is a new technology, it has been around for a long time and it is just not catching on in the United States. Because the construction industry in the United States is change resistant, inefficient, unproductive, and unimaginative. One could imagine this changing – there is a lot of money that could be made and a lot of jobs that could be created. More prefabricated building components is one idea that has been tossed around and around and implemented elsewhere. But decade after decade after decade, we just do not change in the United States. Call it the old American can’t do spirit.

macroinvertebrates (aka worms and bugs) in rain gardens

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Even though the names imply they are living ecosystems, stormwater management engineers still have a tendency to think of rain gardens and bioretention basins as inert systems. It’s good to see the profession working with other disciplines and taking soil science more seriously these days. And where most are focused on physical, chemical, and plant-based processes, a few are looking more closely at the importance of animal activity.

Soil invertebrates in Australian rain gardens and their potential roles in storage and processing of nitrogen

Research on rain gardens generally focuses on hydrology, geochemistry, and vegetation. The role of soil invertebrates has largely been overlooked, despite their well-known impacts on soil nutrient storage, removal, and processing. Surveys of three rain gardens in Melbourne, Australia, revealed a soil invertebrate community structure that differed significantly among sites but was stable across sampling dates (July 2013 and April 2014). Megadrilacea (earthworms), Enchytraeidae (potworms), and Collembola (springtails) were abundant in all sites, and together accounted for a median of 80% of total soil invertebrate abundance. Earthworms were positively correlated to soil organic matter content, but the abundances of other taxonomic groups were not strongly related to organic matter content, plant cover, or root biomass across sites. While less than 5% of total soil N was estimated to be stored in the body tissues of these three taxa, and estimated N gas emissions from earthworms (N2O and N2) were low, ingestion and processing of soil was high (e.g., up to 417% of the upper 5 cm of soil ingested by earthworms annually in one site), suggesting that the contribution of these organisms to N cycling in rain gardens may be substantial. Thus, invertebrate communities represent an overlooked feature of rain garden design that can play an important role in the structure and function of these systems.

Big Bertha

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The problems for Seattle’s “Bertha” tunnel boring project are continuing according to the Seattle Times.

Tunnel-machine Bertha’s two-year breakdown will further delay the Highway 99 tunnel’s grand opening until 2019 and saddle Washington state with an estimated $223 million in cost overruns, lawmakers were told Thursday…

A 2019 opening would mark a full decade since former Gov. Chris Gregoire chose the deep-bore tunnel option and lawmakers approved the tunnel bill sponsored by then-Sen. Ed Murray, now Seattle mayor. Gregoire dismissed critics such as then-Mayor Mike McGinn, who warned that a clause in the bill put Seattle taxpayers at particular risk for paying for overruns…

The extra costs almost certainly would be paid by the state’s drivers in gas taxes, more transportation-fund debt, or by tolls and fees.

Tunneling is a key technology for the future of urban infrastructure. But the experience in Seattle illustrates the risk that the technology entails. It is one thing for state and federal governments to undertake this risk under the oversight of elected officials, and another for state and federal governments to put pressure on local governments and utilities to undertake these types of massive projects, as is common in the water quality and flooding arena. A tunneling project that goes well can indeed often reduce pollutant discharges or flooding at an attractive unit cost, but the costs can mount quickly when a project does not go well. Luckily, that happens only when we do not know in advance precisely what we are going to find underground every step of the way under a city that has been around for a couple hundred years (in other words, always). Tunneling is an alternative that should almost always be looked at. Green infrastructure should be looked at too and considered seriously on its merits as an engineering infrastructure technology that can have multiple benefits for the citizens, taxpayers and ratepayers of urban areas.

vegetable rain gardens

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Growing food in rain gardens – it seems almost too obvious. But it isn’t done much, and somebody has gone to the trouble of studying it scientifically here. They planted “beetroot, onion, spinach, tomato and broad bean”. This sounds good, but it might be fun to experiment with trees and other perennial species. There are some tough plants out there that will tolerate wet and dry conditions better than your typical annual garden crops. Jerusalem artichoke comes to mind, which is a sort of invasive American prairie flower that produces enormous amounts of delicious potato-like tubers.