The High Line--reinventing city infrastructure

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On New York's west side, an old elevated railway had become another blight on the neighborhood. With weeds and small trees sprouting aloft, it presented a strange environment to urban explorers who ventured aloft-- a riot of weeds sprouting among the rusting order of ties and rails.

After plans surfaced for demolishing the railway, two activists from the neighborhood, Joshua David and Robert Hammond, proposed turning the railway into an elevated greenway.

Chip sealing--and how dust affects our lakes

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Today, most concerns about air pollution focus on global warming.  Yet for those of us working for the health of our lakes, air pollution remains an important issue.

Dead fish in Shangri-La

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All around the world, lakes are in trouble--with fish kills or toxic algae blooms.  Usually, the culprit is excess nutrients washing into the lake.  It's happening even at pristine lakes, long thought to be immune to these problems.

From time to time, I'll feature problems of lakes in a different parts of the world.  The root cause is growing populations and affluence, plus the difficulty of managing thousands of small sources of nutrients.

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Indian Kashmir used to be a place people compared to mythical Shangri-La--verdant and unspoiled.  And Nigeen Lake (above), in a green valley surrounded by the Himalayas, is considered by waterways officials to the least polluted waterway in the city of Srinagar (population 1.3 million).

"Chip sealing" of streets generates complaints

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On Madison's west side, City Engineering is in the process of "chip sealing."  This is a maintenance program that extends the life of pavement which is still in good condition.

Steps in the process we observed

• Workers clean out cracks between pavement and curb, and place filters on the stormsewer inlets.
• Asphalt is laid down to seal the cracks in pavement.
• Bottom slag is liberally applied to cover the asphalt, provide traction, and surface protecton.
• A pickup truck drags a rake to make sure the slag is evenly distributed.
• The excess slag is removed in several passes by sweepers.

Complaints are coming from the use of a black, sandy material called "bottom slag."

The loose slag is creating a nuisance for pedestrians and a minor hazard for cyclists.  It's also creating a lot of dust, either when vehicles pass by, or when the contractor drags a rake over the slag--as they are doing in multiple passes (below).

The City claims chip sealing will save millions of dollars over the years.  They also claim that it's environmentally friendly, because it saves natural resources.  In other words, when slag is used on streets, sand doesn't have to be mined.  And, keeping the slag--a waste product--out of landfills saves landfill space.  I don't doubt these assertions.  I just wonder if all the long-term costs of using slag have been accounted for in the "cost-benefit" calculations.