Mountain Valley Pipeline Response to Christopulos Report

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Mountain Valley Pipeline Response to ChristopulosReportGeosyntec Consultants, Inc.

September 4, 2019

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Presentation Outline

• Summary of Assertions in Christopulos Report• USGS Gauge Turbidity Data

– Analysis of long-term historical trends– Comparison of before construction and during

construction– Analysis and comparison of upstream and

downstream turbidity data• Summary and Conclusions

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Christopulos Report Assertions

• Turbidity readings "were higher in 2019 than in 2018"– Due to "the hasty and error-filled clearing and grading of

steep, landslide-prone slopes by MVP" in tributaries to the Roanoke River

• Comparison of three gauges on Roanoke River mainstem– Highest reading (Sept-Dec 2017) was ~600 FNU– Levels >1,000 FNU only once or twice in 2018*– "turbidity stayed high for days" for July 15 to 26, 2019

• "Muddier, in fact, than any of us could ever remember seeing it"• "unprecedented spike" on July 15• "additional significant spiking" on July 21-22

* 2018 was record rainfall year.~1,500 FNU in Oct. 2018 possibly due to clogged gauge.

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Christopulos Report Assertions

• July 15-18, 2019 turbidity– August 2 Virginia DEQ Stop Work Order shows

Bradshaw Creek, North Fork, and Indian Run tributary to South Fork are likely source

• July 21-25, 2019 turbidity– Tributaries at Yellow Finch Road and other locations

entering Roanoke River below Route 11 in Lafayette are likely source

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USGS Gauge Turbidity Data

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Turbidity

• Turbidity is a measure of the degree to which the water loses transparency due to the presence of suspended particulates

• For a given soil type, the more total suspended solids are in the water (i.e., the murkier it appears), the higher turbidity

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USGS Turbidity Gauge Locations

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Roanoke River Gauge Locations

Gauge location with longest period of record,

16.5 miles Downstream of Roanoke River Crossing

(drainage area = 352 mi2)

475 feet Downstream of Roanoke River Crossing

(drainage area = 257 mi2)

650 feet Upstream of Roanoke River Crossing

(drainage area = 256 mi2)

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Roanoke River USGS Turbidity Data

Station taken offline during this period

Turbidity measurements greater than 600 FNU observed Before and During Construction

Note: Turbidity threshold of 600 FNU based on assertion in Christopulos report as highest reading before MVP construction.

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Turbidity & Precipitation Comparison

Overall, similar response trends observed Before Construction (slope=0.515) and During Construction

(slope=0.512) when correlated with precipitation.

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Turbidity & Precipitation Comparison

As precipitation depth increases, maximum daily turbidity generally increases.

More rainfall events greater than 1” for During Construction period, potentially contributing to higher mean and average turbidity at this station.

Overall, similar response trends observed Before Construction (slope=0.628) and During Construction

(slope=0.527) when correlated with precipitation.

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Turbidity & Precipitation Comparison

More rainfall events greater than 1” for During Construction period, potentially contributing to higher mean and average turbidity at this station.

Overall, similar response trends observed Before Construction (slope=0.637) and During Construction

(slope=0.550) when correlated with precipitation.

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Roanoke River USGS Turbidity Data

Location USGS Station Location

15-min Turbidity (FNU)

No. of Observations Avg. Median St.

Dev.95th

Percentile

Roanoke River Along Route 626

0205450393 Upstream 196,760 2.0 9.8 37.1 36.4

Roanoke River Above

Route 110205450495 Downstream 194,106 2.3 11.3 45.9 43.2

Similar statistical summaries observed at upstream and downstream Roanoke River gauges.

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Summary and Conclusions

• Christopulos' assertion that "Turbidity readings were higher in 2019 than in 2018" due to "the hasty and error-filled clearing and grading of steep, landslide-prone slopes by MVP" in tributaries to the Roanoke River is not supported by the data– Higher turbidity values are generally correlated with increased

precipitation– Similar turbidity trends with precipitation are seen Before

Construction and During Construction– Turbidity readings do not suggest a significant increase at the

Roanoke River crossing• Christopulos' assertion that MVP has caused historically high

turbidity ignores the full period of recorded observations and has no basis– Turbidity readings in 2019 are consistent with observations

dating back to 2008– Turbidity values greater than 600 FNU occurred regularly dating

back to 2008

Note: Turbidity threshold of 600 FNU based on assertion in Christopulos report as highest reading before MVP construction.