www.pdhonline.com - Your Gateway to Lifelong Learning   |   Email: PDHonline@Gmail.com   
PDH Online Course Description PDH Units/
Learning Units (Hours)

Buy Now

View Course

View or Take Quiz


Pipeline Construction Across Streams with Resulting Turbidity and Fishery Impacts

H. Wayne Harper, PE

State water quality agencies typically impose turbidity standards on pipeline construction across waterbodies primarily because it is a widely used water quality measurement, is easy to determine in the field, and provides instantaneous feedback to regulatory personnel. However, most state water quality regulations pertaining to turbidity were originally developed for use with chronic long-term point-source discharge situations. The use of these criteria without some adjustment for the short-term nature of construction projects may be a mis-application of the basic concepts behind their original intent. Additionally, regulatory personnel will often use turbidity data to infer fishery impacts. Turbidity, however, has a lesser biological effect on fish than does its often-related measurement, suspended sediment. Portland Natural Gas Transmission System (PNGTS)/Northern Ecological Associates, Inc. (NEA) used established engineering models and grain size analysis to conduct a detailed study of turbidity and suspended sediment dynamics caused by pipeline construction across streams.

To predict total suspended sediment (TSS) distribution and transport, PNGTS/NEA developed scenarios for typical waterbody crossings by assuming representative stream characteristics including: width, cross-sectional area, bed composition, mean velocity, estimated transport distances, material lost during excavation, and the increase in suspended solids expected downstream of the crossing. PNGTS/NEA used sediment grain size analyses that were collected from representative stream crossings as input parameters in the model. PNGTS/NEA’s estimates were then input into Trow’s 1996 model to estimate sediment dispersion for three stream types: low, medium, and high energy. Predicted suspended sediment values were then used to determine lethal and sublethal fishery impacts using Newcombe and Jensen’s mathematical model which assigns a Severity of Ill Effect (SEV) value for fish species guilds based on dose (TSS/ml) and duration (hours) of exposure. The results of this analysis were used in negotiations with state regulatory personnel to help describe potential realistic fishery impacts, rather than hypothetical effects that may be caused by elevated turbidity values.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

View Course Content

NY PE & PLS: You must choose courses that are technical in nature or related to matters of laws and ethics contributing to the health and welfare of the public. NY Board does not accept courses related to office management, risk management, leadership, marketing, accounting, financial planning, real estate, and basic CAD. Specific course topics that are on the borderline and are not acceptable by the NY Board have been noted under the course description on our website.

AIA Members: You must take the courses listed under the category "AIA/CES Registered Courses" if you want us to report your Learning Units (LUs) to AIA/CES. If you take courses not registered with AIA/CES, you need to report the earned Learning Units (not qualified for HSW credits) using Self Report Form provided by AIA/CES.