Archive for May, 2008

Reflections from recent trips across Southeastern Pennsylvania:

Communities are increasingly forced to deal with the long-term impacts of industrialization, where the veneer of economic prosperity ultimately gives away to reveal damaged communities and impaired ecological processes. We visited two sites that are deploying strategies to deal with such post-industrial conditions. One location was Palmerton, Pennsylvania; a Superfund town nestled in the bucolic backdrop of the Kitatinny Mountains. The other was Philadelphia’s Mill Creek, which is currently encapsulated within enormous sewer pipes underneath the city. The sustainable practices at Palmerton and Mill Creek provide some insight on how to design strategies that restore the ecological functions of highly impaired environments.

Palmerton Superfund Site

In 1898, Palmerton was founded as a factory town, nestled between two ridgelines, to conduct zinc smeltering during the height of industrialization in the United States. After decades of constant smeltering, the forest ecosystem collapsed, affecting an expanse of nearly 2,000 acres. Due to deposition of zinc, lead and cadmium from the furnaces, microorganisms in the soil substrate were killed off, and an integral component of the forest lifecycle ended. Without decomposers, nutrients in the soil were eliminated, leading a domino effect that decimated the forest. To date, it is the largest Superfund site east of the Mississippi River.

On site, I was struck by the eerie landscape of windswept, bleached trees amongst barren grounds of dry dirt. Abandoned, rusted factory facitilies stood like sentinels to remind residents and visitors of a foregone era. Amazingly, some plant and wildlife species are returning to the environment; numerous sprouts of sassafras and sourgum were seen emerging from gnarled trunks.

Due to the immensity of the contaminated area, removing the toxic substrate was out of the question. We learned about two strategies to rebuild the soil nutrients, with the goal of creating a capping layer of substrate above the contaminated soils. The first attempt to “green” the decimated slopes entailed terracing the mountain to establish over 60 miles of roadways. These costly roads provided access for trucks to spray “ecoloam” along the slopes. Ecoloam was an engineered growing medium composed of sludge and schlag material from city waste. From afar, this method successfully “greened” the mountainside. However, some critics of this method blame the pervasive amount of invasive species on the applied slopes, due to the unpredictability of the seed composition of the ecoloam mixture. Additionally, trees could not establish beyond the depth of the ecoloam because the roots would hit the contaminated substrate beneath.

The land now belongs to telecommunications monolith known as Viacom, as a side acquisition through various transactions. To its credit, Viacom is funding the implementation of the second strategy, which relies on the hardiness of warm season native grass species to restore and stabilize the mountain slopes. Based on a serpentine barren-type ecology, this strategy aims to mimic the type of succession that had occurred in the site’s geological glaciation context. To establish the grasses, a growing medium composed of limestone, commercial fertilizer, grass seeds and compost was sprayed from the air, or hand-dropped along the slopes. This method appears to be less disruptive of the mountain slope because roads are not necessary, and the warm season grasses seem to be growing quite successfully.

In addition to the warm-season grasses, the predominant plant species we observed included the gray birch, sassafras, poplar, aspen and chestnut oak trees. Furthermore, some rare plant species were thriving quite well in these extreme conditions, such as wild bleeding heart and sandwort. Despite the calculated efforts to establish native plants, invasive species continue to pose a threat to the restoration efforts. As such, the staff work hard to eradicate the butterfly bush and ailanthus tree that they find along the slopes.

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