Volume balance and toxicity analysis of highway storm water discharge from Cross Lake Bridge.

Details

• Creators:
  Griffin, D. M.
• Corporate Creators:
  Louisiana Transportation Research Center
• Corporate Contributors:
  Louisiana. Dept. of Transportation and Development
• Subject/TRT Terms:
  • Drainage basins
  • Drainage structures
  • Runoff
  • Drainage
  • Water pollution
  • Measurement
  • Urban runoff--Management
  • Runoff--Louisiana--Shreveport
  • Bridges--Drainage systems
  • Water--Pollution--Measurement
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• Publication/ Report Number:
  FHWA/LA.09/447
• Resource Type:
  Tech Report
• Geographical Coverage:
  Louisiana
• Edition:
  Final report; May 2003-Aug. 2009.
• Corporate Publisher:
  Louisiana Transportation Research Center
• Abstract:
  The Cross Lake Bridge in Shreveport, Louisiana, spans Cross Lake that serves as the city’s water supply. Concern ; about accidents on the bridge contaminating the lake prompted the Louisiana Department of Transportation and ; Development (LADOTD) to construct a closed drainage system on the bridge to convey precipitation falling on the ; bridge deck to a concrete lined holding pond on the east side of the lake. Once there, bridge runoff is tested for oil ; and grease, pH, and lead before discharge to 12-mile bayou. ; This report describes the methodology and results of two studies dealing with runoff from the Cross Lake Bridge. ; The first examined the degree to which repairs to the Cross Lake Bridge’s closed drainage system were successful ; in capturing runoff from the bridge. An earlier study found that, because of leakage, only about one half of the ; precipitation falling on the bridge actually ended up in the holding pond. This is substantially less than would be ; expected from a catchment that is essentially impervious. To test the success of repairs to the drainage system, ; volume balances for 22 precipitation events were conducted by comparing the rainfall on the bridge to the ; subsequent flow into the pond. The ratio of the volume of runoff to the volume of precipitation was found to ; average 0.86, which when compared to values from the previous study as well as published values, suggested a ; successful repair of the drainage system. ; The second study examined the use of the Microtox toxicity analysis system manufactured by Azur Environmental ; for use as a screening tool to assess toxicity of the pond contents. Microtox protocols rely on measurement of light ; output from a specific strain of luminescent bacteria. Toxicity is indicated when light output from the bacteria ; decreases. Tests can be run in time periods ranging from 5 to 30 minutes. The standard endpoint of the tests occurs ; once light output has dropped 50 percent and is termed the EC50. Samples from the water column and sediment ; were collected and analyzed for toxicity using the basic test (liquid) and the basic solid phase test (sediment).
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/16955/dot_16955_DS1.pdf
• File Type:
  [PDF - 220.35 KB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:58992489ef139e97002df2d8fdc3158e75acf9b3a451954221002ab5b2eab555