Portland State University

The video begins at 12:44.

Abstract: Average Portland rainfall is nearly 37 inches a year. This rainfall usually runs off streets and other impervious surfaces such as roofs and into the sewer system, but this can cause two major problems. First, disposing of runoff in a storm sewer that drains to a river or stream sends dirt, metals, oil, pesticides, and other pollutants right into the water. Second, in neighborhoods with combined sewers, (that is, sewage systems that combine household sewage with the runoff waters from rain), after a heavy rainfall, the high volume of sewage sent to be treated can overwhelm the treatment center and lead to raw sewage discharges into the Willamette River. About 27% of the city is covered by buildings, streets, sidewalks, and other hard, or impervious, surfaces. Paved streets cover about 19% of Portland’s land area, but those streets account for nearly half of Portland’s impervious surfaces. Paved streets contribute 66% of the total annual stormwater runoff and 77% of the pollutants in the runoff. To address this problem, the City of Portland has begun investing in ways to treat stormwater runoff before it enters the sewer system. The city has built and is developing a number of “green street” projects that mimic what happens to rain when it falls on undeveloped areas. A green street uses landscaped curb extensions, lowered infiltration planters and basins, swales, trees,...

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PRESENTATION ARCHIVE

• Video
• Presentation Slides
• PDH Certificate

OVERVIEW

Recreational trails serve as valuable transportation corridors and support the health of users. Wheelchair accessibility of recreational trails depends on a variety of conditions, including slope, cross-slope, and surface characteristics. This project focused on improving the firmness and stability of a 0.2-mile section of trail that was otherwise accessible. The existing trail surface consisted of loose ¼” off-specification aggregate on native soil. A volcanic ash-Portland cement binder, studied in prior research, was batched, distributed, mixed, wetted, and compacted on site to improve the firmness and stability of the surface resulting in a smoother surface with less rolling resistance. The webinar will present details of the trail conditions, materials, batching, placement, and surface characteristics before and after treatment.

KEY LEARNING OUTCOMES

Attendees will be able to:

• Describe and differentiate pozzolanic and cementitious...

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The video begins at 2:35.

“We are faced with a grave crisis that may change our way of life forever. We live in a civilization that evolved on the promise of an endless supply of cheap oil. The era of cheap oil will end, probably much sooner than most people realize. To put this looming crisis in perspective, and to judge its significance, it helps to start from the beginning.”

In this presentation Dr. Goodstein examines the rapid disappearance of oil and predicts its depletion will arrive much sooner than projected. Imagining a world caught suddenly, and perhaps unprepared, without oil, Dr. Goodstein discusses the alternatives and their implications for the environment.