Title

Pipeline Construction Impacts on Small Mountain Streams: Evaluating Stream Geomorphology, Water Quality, and Benthic Macroinvertebrate Diversity

Student Classification

Sophomore

Department

Engineering

Document Type

Poster

Publication Date

Spring 2019

Abstract

The Mountain Valley Pipeline is a natural gas pipeline crossing through Appalachian karst geology and mountain streams posing environmental concerns. Deforestation and construction on mountain grades can increase erosion and release nutrients, which can affect small streams. By examining stream morphology, sediment deposition, water quality, and benthic macroinvertebrate diversity we characterized four reaches in the Mill Creek watershed (Montgomery County, VA): two isolated from pipeline construction and one on each side of the pipeline right-of-way. To identify physical stream health and relative impairment, we measured stream geometries and classified stream substrate to calculate relative bed stability. We installed embedded sediment samplers above and below the pipeline right-of-way to capture fine sediments for a comparison of quantity and composition. In addition, we measured water quality using a hand-held water quality sonde (YSI) and grab samples. We determined benthic macroinvertebrate diversity using modified procedures from the EPA's Rapid Bioassessment Protocol. Samples from above and below the pipeline crossing, with varying distances, were quantified and aggregated. Study results provided quantitative and visual evidence that the below pipeline stream was physically altered compared to upstream or isolated sites. The downstream site had greater sediment loads, evident in our bed sediment sampling and pebble counts, along with an impairment rating utilizing relative bed stability methodology. However, ecologically, the benthic macroinvertebrate community showed minimal variation by site and longitudinal distances. This study sufficiently establishes baseline information; further monitoring should evaluate physical stream properties and ecosystem health as pipeline construction continues and reclamation plans are implemented.

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