Hydrogeologic Evaluation is incomplete and illustrates potential severe violations of Mining Act-Umstead Coalition (Comments 3 of)

The Umstead Coalition
me P.O. Box 10654
Umstead Raleigh, NC 27605-0654
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B. W. Wells Association
New Hope Audubon Society
NC Native Plant Society
Capital Group Sierra Club
Neuse Riverkeeper Foundation
Orange -Chatham Group Sierra Club
Eno River Association
NC Herpetological Society
Raleigh Ski and Outing Club, Inc.
Friends of State Parks
NC League Conservation Voters Foundation
Rockingham Naturalist's Club
Headwaters Group Sierra Club
NC Wildlife Federation
Friends of Jockey's Ridge
Wake Audubon Society
May 7, 2020
Mr. Brian Wrenn, Director
Division of Energy, Mineral and Land Resources
N.C. Department of Environmental Quality
1612 Mail Service Center
Raleigh, N.C. 27699-1612
Subject: The submitted NC Mining Permit Application — 92-10 Modification to expand permitted area —
Hydrogeologic Evaluation indicates and Incomplete Application and Evidence for "adverse effects on
groundwater supplies," "violations of groundwater quality," and "adverse effect on the purposes of a
publically-owned park"
Mr. Wrenn:
Please accept this letter as our part of our initial comments on the "Hydrogeologic Evaluation of the
Triangle Quarry" aspects of the submitted Mining Application referred above.
I write this set of comments on behalf of The Umstead Coalition. My comments are backed by the
knowledge and experience of my 35 years of experience on the faculty at NC State University working
with watershed projects in NC and the US, coordinating with other Universities, USEPA, and other
Federal agencies and State Agencies. In addition, my comments on the "Hydrogeologic Evaluation of
the Triangle Quarry" appendix have been strengthened with substantial input from Dr. Garry Grabow,
Professor Emeritus, Biological and Agricultural Engineering Department, NC State University.
Section 1.0 (Introduction) of the GMA report correctly states:
"As apart of the mine permit documents, Wake Stone must evaluate potential impacts on the
groundwater system associated with dewatering of the new open pit mine. Because Crabtree Creek
borders the expansion property to the south and east, the groundwater evaluation must also address
potential interactions between the proposed mine and surface water flow in Crabtree Creek."
The GMA study and report do NOT answer either of these questions. The hydrogeological study is
anemic due to inappropriate experimental design and insufficient data. The statements/conclusions
made by Wake Stone Corporation and Groundwater Management Associates (GMA) regarding the
study are unsubstantiated. In contrast, the "Hydrogeologic Evaluation of the Triangle Quarry" suggests
a high probability of major water quality and quantity adverse effects violations of groundwater quality
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Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

from the proposed new quarry, potential for adverse effects on a drinking water supply, and adverse
effects on the purposes of William B. Umstead State Park. The "Hydrogeologic Evaluation of the
Triangle Quarry" supports the outcome of, at best, of incomplete application; but indicates reasons for
denial of the proposed Mining Permit Modification.
Key missing data:
• Elevations (MSL) and depth from existing ground surface of the various layers of rock. This
information is needed for numerous transects from top of proposed Odd Fellows Tract pit and
Crabtree Creek. This data is required to evaluate the surface/ground water interactions between
Crabtree Creek and the Odd Fellows Tract currently and with the proposed future pit.
• (also a required element, but missing, in Application under Reclamation Plan D.2). Scaled cross -
sections of the final proposed pit with final water elevations, as well as the existing pit, utilizing
the "Future Pit perimeter". This must include the land area from bottom of the proposed pit to
Crabtree Creek in various transect locations.
• Calculation of the rates to fill the existing and the new pit and the contribution rates from each
water sources. The sump pumping data provided in the GMA report would indicate a time period
of over 100 years to fill the existing pit. And, the hydraulic conductivity for the new pit has not
been adequately estimated.
• Detailed soil and rock core data for depth of rock. This data is required to help estimate the
hydraulic conductivity of the remaining soil and rock between the pit and Crabtree Creek.
• In the (unlikely) event that the pits do will with water, how will the excess water be handled?
The proposed site plan does not account for the safety and integrity of such an impoundment.
• Elevation of Crabtree Lake (average and at days of sampling streamflow). The cited value of
274 MSL is in conflict with other public records (actual measurements, not just estimates).
• Elevation of Crabtree Creek — base and stormflow conditions at various locations along the
approximate 1.5-mile reach from 1-40 to Triangle quarry discharge into Crabtree Creek. (actual
measurements, not just estimates)
• Groundwater well transects perpendicular to Crabtree Creek at various location along the 1-mile
reach from I-40 to William B. Umstead State Park, collected over seasons to measure the depth
to groundwater and ground water gradients
• Hydraulic conductivity measurements
Issues with Surface Water Measurements and Conclusions
Section 2.2 Hydrology of Crabtree Creek
The streamflow perturbation from areas upstream of the mine is not the issue at hand, but rather
perturbation caused by the quarry. If streamflow is perturbed upstream (e.g. a change in WWTP
outflow) over the course of a stream gaging campaign (the half -day or day) then yes it would make
assessment of impact more difficult if flow changed due to other upstream sources between gaging
stations upstream and downstream of the quarry. The fact speaks to the uncertainty and inadequacy of
the one -day sample presenting in this report.
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

Section 3.1 Stream Flow Study
The stream gaging sampling method using only the 0.6 depth adds uncertainty and does not follow the
recommended USGS protocols. Discharge should not be calculated as the product of the surface water
velocity and the cross -sectional area of water in the channel, but rather the product of velocity at
(preferably) 0.2 and 0.8 depth, or if the equipment cannot obtain readings of 0.2 and 0.8 depth, 0.6
depth due to equipment size. GMA should have just left out "surface", or hyphenated "surface -water"
as when you do current metering it is obviously surface water (and not groundwater) one is measuring.
GMA took measurements at 0.6 of the depth. Normally one uses 0.2 and 0.8 depths and only reverts to
a single 0.6 depth measurement under equipment constraints. The standard depth measurement are
given on Page 32 of USGS Techniques of Water -Resources Investigations, TWRI book 3, chapter A8
(not cited in the GMA report, but attached and available at:
https://pubs.usgs.gov/twri/twri3a8/html/pdf.html). This document is not cited by the GMA report, but is
cited in the Meals and Dressing (2008) Tech Note 3. The Meals and Dressing (2008) Tech Note 3 also
suggests 0.2 and 0.8 depths be used consistent with USGS recommendations. The USGS TWRI book
mentions the vertical measurement options, and says the USGS constrains use of the single 0.61)
measurement to water depths up to 2.5 ft. Several cross-section stations at Station 2 and a few at Station
1 exceeded at depth of 2.5 ft.
The velocity meter GMA used has a propeller housing of 2 in. diameter. It claims to be able to measure
flow in streams down to a 2 in. depth. The device is rather small and does not have a USGS type rod
associated with it so could physically measure to fairly shallow depths and would allow for a 2- point
method for depths below 2.5 ft., although probably not too much below this total depth. It is difficult to
assess what increase in accuracy this would have resulted in, but likely not much since there were
limited cross-section stations with depths greater than 2.5 ft.
The GMA utilizing incorrect terminology. The associated Figure is not labeled correctly. Figures 5
through 8 are "stream cross -sections" not "channel profiles." Table 1 shows stream flow rates, labeled
correctly as Q. However, the text and Figure 3 refers to stream flow rates as "volume" which is
incorrect.
4.1. Crabtree Creek Flow Monitoring
Only 1 set of measurements were taken on January 30, 2020. From the photo and statement Crabtree
Creek was a wadeable stream. The last significant rain occurred on January 25, 2020 with 0.55 inches
recorded at RDU. These basic facts should be included in such a study, but were missing. Given the
admitted +/-6% accuracy and only one(1) data point under one set of conditions, the data presented is
difficult to assess.
But, let's assume for discussion sake that the streamflow measurements were somewhat accurate. This
study does NOT support the existing quarry is not having a negative impact on Crabtree Creek. And, if
anything is indicative of potential stream flow issues with the existing quarry which would worsen if a
new quarry pit is built on the Odd Fellows side of Crabtree Creek.
Our guess is that they are trying to show that the flows at Station 1, 2, and 3 (after accounting for the
tributary flow) are essentially the same and therefore the existing quarry has no impact on the Creek as it
flows the approximate 1.5-mile distance from I-40 to the end of the current quarry operation (see Figure
4 for station locations). This is in conflict with the statement in the GMA report that acknowledges
Crabtree Creek surrounded by a forested watershed receives groundwater contributions (page 3, last
paragraph). In a healthy, forested watershed, given the fairly steady rainfalls in the proceeding month,
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

Crabtree Creek should be receiving water (a "gaining" stream) from its surround groundwater sources.
A "flat" stream flow over the 1.5-mile reach shows no evidence of net ground water movement into
Crabtree Creek.
A healthy forested stream would be expected to be gaining stream under the previous weather conditions
of this study. The lack of any evidence for a gaining stream in this stretch is troublesome. If the Odd
Fellows Tract were deforested, overburden removed, and a deep pit dug, the source of shallow ground
water regard would be depleted on both sides of Crabtree Creek. The result would likely be the creation
of a "loosing" stream, e.g., the surface water within Crabtree Creek moving OUT into the adjacent
shallow groundwater. This could have dire consequences for the North Cary Water Reclamation Plant
just upstream — their surface water discharge could then become a groundwater discharge — with a whole
new set of ground water standards.
Let's look at the Crabtree Creek reach that lies within the forested William B. Umstead State Park. The
presented data support that this section Crabtree Creek is a healthy, gaining Piedmont stream. The GMA
report appendixes include a USGS stream gage as Crabtree exits the Park at Ebenezer Church Road,
about 3-4 miles downstream of the quarry. There is an increase of discharge between 12:00 and 16:00 on
Jan. 30. If you subtract about 4 hours (assuming a velocity of about 1 fps which is roughly taken from
the current meter data in the appendix and assuming about 3 miles of travel to the Ebenezer Church Rd.
station) you will see that roughly matches the range in time for current metering for stations 1-3. Those
report a pretty constant flow. So the Ebenezer Church road station is gaining flow (accretions) at the
later time at which you would expect any "pulses" to come through, while the upstream stations are not.
It is pretty difficult to reconcile change in flow rates although from the data it appears that from the
GMA measured locations to Ebenezer church road, overall the stream WITHIN William B. Umstead
State Park is a gaining reach (higher flows at Ebenezer Church Road) while the reach between station 1
and State Park is not. There was no rainfall recorded at RDU that day (Jan. 30) and no significant rain
in the previous 4 days.
Another large potential issues not fully evaluated with this limited study is the potential negative effect
on Crabtree Creek streambank stability due to:
• Increase stormwater discharge (e.g., "flashy") due to loss of soil infiltration (due to the lack of
soil)
• Increase stormwater discharge due to diversion of rainfall from infiltration through a forested
watershed into "pipes"
• Decreased base flow recharge due to the loss of soil and shallow ground water storage and
decreased soil infiltration
• Lack of soil mass between the top of pit and streambank
• Lack of an overflow from "future water impoundment"
• Ridiculously narrow stream buffers on steep slopes between 2 deep pits (100 ft. from center of
Crabtree Creek, far less from top of bank). And, much of the buffer disturbed by fences,
deforestation, retaining wall, bridge, future unknown, etc.
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor 4

The arguments given for the lower downstream discharge are weak. The old dam would have little
effect since it would be overflowing anyway. There could be a slight "routing effect" i.e., a rising or
lowering of the water surface behind the dam under unsteady flow conditions (varying inflow to the dam
over time), but that could go either way (a slight increase of decrease if discharge over time over the
dam weir). The sandbar effect would be inconsequential and could also go either way. If you think
about it, in order for the sandbar to "absorb" water as they say, the stream gage height would have to
increase, and of course an increase in stage height converts to an increase in discharge. So that is
counter to their logic.
Adverse effect the flow rates and hydrographs in Crabtree Creek will negatively affect Crabtree Creek
hydrology, habitat, and therefore, the purposes of a William B. Umstead State Park to conserve and
protect North Carolina's natural beauty, and ecological features.
Issues with Groundwater Measurements and Conclusions
Section 2.1. Local Hydrogeology of the Proposed New Mine Site: The characteristics of the proposed new
mine cannot be based upon the existing mine on the other side of Crabtree Creek. The permeability of
the rock for proposed new mine is likely NOT the same. The report acknowledges the rock structure
differs between the existing quarry site and the Odd Fellows Tract. However, the generalized map from
Blake et al. (2000) fails to provide site -specific rock type, depth and structure. Without numerous core
data from the Odd Fellows tract, information about this site is speculative and approximate, therefore
inadequate to draw conclusions.
The groundwater recharge for the Triangle Quarry site is estimated from Heath (1984). The Heath
information would be very general and not site specific. There is a big problem in this section of the
report, the pit has now been removed from the aquifer, which means that no recharge can be attributed to
the footprint of the quarry. The quarry cannot both be a recharge area and a place where groundwater
discharges as a result of pumping. The area around the pit is a groundwater recharge area, not the pit.
The pit becomes a discharge area due to pumping. Groundwater resulting from recharge from land
around the pit can flow into the pit through fractures/apertures in the rock. As long as the pit is pumped,
it is not a groundwater recharge area and that means there is no recharge within the foot print of the pit.
The pit receives rainfall and groundwater flowing into the pit from adjacent recharge areas. The
groundwater recharge rate Heath estimated is the proportion of rainfall that infiltrates the land surface
and reaches the water table (about 9 inches). Call it rainfall infiltration recharge. The remaining rainfall
is evapotransporated or runs off without becoming groundwater. Combining rain falling into the pit with
rainfall infiltration recharge into the same area of the pit is double counting.
If you take the numbers as is, a recharge rate of 60,000 gpd (42 gpm) with their stated average pumping
to include non -pumping days (139 gpm) that would mean that they are pumping out more than the mine
is being "recharged." There is no real conclusion that can be based on this since the "recharge rates"
cited are generalized and would have a great deal of uncertainty, especially when applied to any one
specific location. Also, the treatment of recharge area is not correct. Recharge area is specific to a
withdrawal point, e.g. well, or discharge area, e.g., stream and is the area from which the discharge point
receives its water. So, the recharge and discharge areas are not co -incident as implied in the report text.
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

Sec. 3.2. Groundwater Evaluation.
If the invert of the stream — that appears to be somewhere between elevations 250-260 near the existing
quarry from the USGS Cary USGS 7.5 min. quadrangle (attached) - was used as a groundwater
elevation (as implied in the text that describes the data used to construct a groundwater elevation map)
then Crabtree creek is an effluent stream (from the perspective of the groundwater) and thus receiving
groundwater base flow from the Northwest (see fig. 10, Odd Fellows Tract). It appears that
approximately 3,000 linear feet of stream could be impacted going from the dashed line indicating the
proposed new quarry. Essentially the pit would become a drain that intersects groundwater discharge to
the stream. I don't know the magnitude as that would depend on the accuracy of their map and the
intervening horizontal hydraulic conductivity.
Fig. 11. seems to be in conflict with itself. If these indeed are equipotential lines, then the existing pit is
an open sink (or drain), i.e., groundwater would flow to the open pit normal to the equipotential lines,
with a flowrate determined by the horizontal hydraulic conductivity. There cannot be a gradient within
an open pit. If it were an equipotential surface (where water would rise to if a well is punched into the
ground if confined or the existing groundwater surface if unconfined) then in an open pit there would be
one level. If the figure is drawn more realistically, the contours (gradient) must stop at the edge of the
existing mine. I really don't know how they drew the equipotential contour lines with so few
groundwater level locations, and with no locations east or north of the existing mine. The bottom of the
mine is about -80ft AMSL and the sump at -40 AMSL so the water table (groundwater surface
elevation) at the edge of the mine is substantially higher (265 for core N that is closest to the pit).
Sec. 4.2. Groundwater Evaluation Discussion
The cone of depression would end at the edge of the existing quarry, not in the middle as drawn. The
"core N GW elevation was measured at 265.02 and is on the equipotential line of 260. This is not a "big
deal" in and of itself but it does show that they did not use an exact interpolation routine like kriging to
obtain their contours. Kriging is an exact interpolator that returns the measured value at the measured
point. The nice thing about kriging is that is also provides a measure of uncertainty (based upon the
modeled semi-variogram) so that you can also map uncertainty with the rendered map. In any event the
number of monitoring wells makes it very difficult to draw any sort of a halfway accurate equipotential
surface. You can see general gradients just by looking at the monitored sites.
It is baffling why GMA did not conduct some in -situ hydraulic conductivity tests (e.g. slug or bail tests)
in the wells they bored. A pressure transducer or some other method of recording groundwater level
recovery would need to be done for such a test. That would at least given some indication of hydraulic
conductivity in the proposed new quarry area.
The study does not support the final conclusion in the GMA report. In contrast, it reveals strong
concerns that the new pit, especially in conjunction with the existing pit across from Crabtree Creek will
result in water being drawn from Crabtree Creek in to the local groundwater — causing violations in
groundwater quality.
In addition, this study does NOT provide evidence that the private residential well (Dunn's property)
will be protected. In contrast, it reveals great danger of "adverse effects on groundwater supplies."
In examination of the "Future Pit Perimeter" on the GMA figures, the pit would consume almost the
entire Odd Fellows Tract. The existing streams and Foxcroft Lake would be starved of their shallow
ground water recharge sources.
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

References (Grabow and USGS attached):
Grabow, G. 2012. Flow Measurement. Class Notes for BAE 576, NC State University (attached).
USGS Cary USGS 7.5 min. quadrangle (attached)
USGS Techniques of Water -Resources Investigations: General Procedure for Gaging Streams TWRI
book 3, chapter A6 (attached)
USGS Techniques of Water -Resources Investigations: Discharge Measurements at Gaging Stations,
TWRI book 3, chapter A8 https://pubs.usgs.gov/twri/twri3a8/html/pdf.html (accessed May 6, 2020)
(attached)
Donald W. Meals and Steven A. Dressing. 2008. Surface water flow measurement for water quality
monitoring projects, Tech Notes 3, March 2008. Developed for U.S. Environmental Protection Agency
by Tetra Tech, Inc., Fairfax, VA, 16 p. https://www.epa.gov/sites/production/files/2016-
05/documents/tech notes _3_dec2013_surface _flow.pdf (accessed May 6, 2020)
�e�
Dr. Jean Spooner
Chair
The Umstead Coalition
CC
The Honorable Governor Roy Cooper
Mike Regan, Secretary, NC Department of Environmental Quality (NC DEQ)
Sheila C. Holman, Assistant Secretary for the Environment, NC DEQ
Susi H Hamilton, Secretary, NC Department Natural and Cultural Resources (NC NCR)
Reid Wilson, Chief Deputy Secretary, NC Department Natural and Cultural Resources (NC NCR)
Dwayne Patterson, Director, NC Division of Parks and Recreation, NC NCR
Brian Strong, Deputy Director, Planning and Natural Resources, NC Div. of Parks and Recreation, NC NCR
Robert E. Johnson, PIO, Division of Energy, Mineral, & Land Resources (DEMLR), NC DEQ
David Miller, State Mining Specialist, DEMLR, NC DEQ
Judy Wehner, Assistant State Mining Specialist, DEMLR, NC DEQ
Nat Wilson, Chief, Ground Water Management Branch, DWR, NC DEQ
Dr. Kenneth Taylor, Geological Survey
Scott Vinson, Regional Supervisor, DWR Raleigh Regional Office, NC DEQ
Paul Wojoski, 401 Unit, DWR, NC DEQ
Honorable NC Senator Wiley Nickel
Honorable NC Representative Cynthia Ball
Honorable NC Representative Joe John
Greg Ford, Chair, Wake County Commissioners and Wake County Commissioners
Wendy Jacabs, Chair, Durham County Commissioners and Durham County Commissioners
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor

Mary -Ann Baldwin, Mayor, City of Raleigh and Raleigh City Council Members
Steve Schewel, Mayor, City of Durham and Durham City Council Members
Harold Weinbrecht, Mayor, Town of Cary and Town of Cary Council Members
TJ Cawley, Mayor, Town of Morrisville and the Town of Morrisville Council Members
Sean Stegall, Town Manager, Town of Cary
Cassie Gavin, Attorney, N.C. Sierra Club
Cynthia Satterfield, Acting Director, N.C. Sierra Club
V The Umstead Coalition v
Dedicated to preserving the natural integrity of W.B. Umstead State Park and the Richland Creek Corridor