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Sediment Production from Unpaved Oil Well Access Roads in the Allegheny National Forest

The Center for Dirt and Gravel Road Studies at Penn State University has been working to reduce sediment pollution generated by unpaved roads in Pennsylvania for over a decade. Runoff from unpaved roads is a large source of sediment pollution in many forested watersheds. The Allegheny Nation Forest, located in Northwestern Pennsylvania, has over 1,695 miles of unpaved access roads that serve the shallow oil wells in the Forest (USDA-FS unpublished, 2010a). The purpose of this study was to quantify sediment generation rates from these oil access roads in the Allegheny National Forest. In addition, the objective of phase II of the study was to determine differences in sediment production after new aggregate had been placed on 4 of the sites. The experimental approach taken in this study was to use a rainfall simulation device to create a repeatable rainfall event and collect sediment load data. The rainfall simulator was used to collect sediment in road runoff on 14 sites, each of which was 100’ in length. The simulated rainfall event was 0.61” in 30 minutes which has a return interval of slightly less than 2 months. The 14 sites tested showed sediment productions ranging from 3.2 to 60 pounds of sediment for each 30 minute simulated rain event. The average sediment runoff from the sites was 24.7 pounds, which equates to a sediment production rate of 1,300 pounds per mile for each 30 minute simulated rain event. Extrapolation of these results indicates that a single storm of similar intensity and duration to the design storm could be expected to produce over 1,100 tons of sediment from the oil access roads in the Allegheny National Forest. An estimated 385 tons of that sediment can be expected to enter directly into nearby streams during each storm. The study also identified a significant ‘first flush’ effect on the road segments studied. Additionally, road segments that received more traffic have been more compacted and exhibit higher structural strengths. Without traffic stress, the best indicators of sediment production from the roads tested were road slope combined with road width. If the road is stressed by traffic, then sediment production becomes less dependent on road width and slope, and more dependent on road strength as measured by the California Bearing Ratio. Finally it was observed that sediment generation would be greatly reduced from roads with very low usage by establishing vegetative cover on the road surface. After initial testing, 4 of the 14 sites were surface with new aggregate material. Two sites were surface with local “pit run” material as is standard procedure. Two of the sites were surfaced with Driving Surface Aggregate. The 4 sites were then tested a year later to determine sediment production. All four sites showd reductions in sediment production (39% and 65% for pit-run, 67% and 65% for DSA). The two pit-run sits averaged ten times as much sediment production as the DSA sites (26.1 lbs versus 2.5 pounds).

  • Record URL:
  • Corporate Authors:

    Pennsylvania State University, University Park

    Center for Dirt and Gravel Road Studies
    University Park, PA  United States  16802

    Department of Energy

    National Energy Technology Laboratory, 626 Cochrans Mill Road
    Pittsburgh, PA  United States  15236

    URS Corporation

    626 Cochrans Mill Road
    Pittsburgh, PA  United States  15236

    USDA Northern Research Station

    335 National Forge Road, P.O. Box 267
    Irvine, PA  United States  16329
  • Authors:
    • Bloser, Steven
    • Scheetz, Barry E
  • Publication Date: 2012-3-26

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 62p

Subject/Index Terms

Filing Info

  • Accession Number: 01375836
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 18 2012 4:12PM