1. GEOLOGIC AND HYDROGEOLOGIC CONDITIONS
AT AND IN THE REGION SURROUNDING
THE HERCULES LIMESTONE QUARRY,
STOCKERTOWN, PENNSYLVANIA
Assessment of the Potential Impacts of
Quarry Dewatering on
Local Groundwater and Surface Water Resources
with an Emphasis on
Proposed Deepening of the East Pit
to 50 ft msl

2. Pumping from quarry was ~ 54
Million Gallons per day or ~ 84 cfs
WQIZ
Stream losses were determined to be
~30 million gallons per day or ~ 46 cfs
A recirculation cell was
hypothesized

3. The U.S.G.S. speculated that
there could be a “Hypothesized
Fracture Zone with Large
Hydraulic Conductivity.”
Risser, 2006

4. MW-1
MW-4
PADEP-06
MW-2
West quarry
MW-8
inflow zone PADEP-03
PADEP-04
MW-6R
MW-3
PADEP-05
PADEP-01
PADEP-02

5. Grout Curtain
WQIZ
Nazareth
In an attempt to eliminate the
hypothetical recirculation, a
grout curtain was installed in
2008.
ESSROC
Quarry

6. Data generated during and since the installation of
the grout curtain provided for an expanded
understanding of hydrogeologic conditions

7. The previous conceptualization was
of a single, unconfined aquifer as
the source of the quarry inflow. The
boundaries were assigned based on
a combination of the observed
limits of stream flow losses in the
Bushkill and Schoeneck Creeks and
water balance, assuming a uniform,
standard recharge rate.

8. Data from the post-grouting period supports a
conclusion that there are two distinct groundwater
systems: a shallow unconfined system which occurs
in the epikarst zone and a deep confined system.
The currently proposed quarry deepening would
occur wholly within the unconfined aquifer zone. .

9. Buzzi Cement Stockertown
Plant
WQIZ
The grout curtain failed to
Nazareth
eliminate WQIZ inflows, but
achieved a maximum reduction of
Tatamy
flow of approximately 10%
Various investigators hypothesized
that the conduit flow bypassed the
curtain in the subsurface by
ESSROC
Quarry flowing around the ends.

10. The questions which had to be answered were:
Does extraction from the WQIZ derive water from the
Bushkill Corridor?
Is there a conduit of large conductivity?
Are the two groundwater zones distinct hydraulically?
Will extending the depth to 50 ft msl adversely impact
local or regional water resources?

11. The answers to those questions required a
re-assessment of both the geology and
hydrogeology of the quarry and the surrounding
area.

12. Beginning of influent Explanation
stream conditions
Geology Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
Outcrop of
Jacksonburg Fm
Ob Beekmantown
Group
Ojb Groundwater
Flow
D U

13. Beginning of influent Explanation
stream conditions
Geology Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
. Outcrop of
Jacksonburg Fm
Ob Beekmantown
Group
Ojb
There is a pervasive SW-to-NE trend of all Groundwater
Flow
structural features
D U

14. Geology
Karst solution features follow the same
general SW-NE trend and also plunge
toward the NE.

15. Beginning of influent Explanation
stream conditions
Geology Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
The hypothetical conduit of Risser Outcrop of
Jacksonburg Fm
would be off trend and would, of Beekmantown
Ob
necessity, have to plunge SW. Group
Ojb Groundwater
Flow
D U

16. Beginning of influent Explanation
stream conditions
Geology Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
In fact, both the trend and Outcrop of
plunge of the hypothetical feature Jacksonburg Fm
Ob Beekmantown
are not plausible: the trend Group
Ojb would be inconsistent with the Groundwater
Flow
entire tectonic setting and the
D U
plunge, if present, would have to
be eastward.

17. Hydrogeology

18. The quarry is in the outcrop area of the
Jacksonburg Formation near the
contacts with the Martinsburg Fm (up
section) and Epler Fm (down section).
Within the outcrop area of the pelitic
Martinsburg Formation the stream is
effluent.
The reach of stream over the paleokarst
Jacksonburg Formation is perched
above an aquifer which is in the
epikarst zone.
The reach of stream from the contact of
the Epler Formation with the
Jacksonburg Formation is a classic,
influent karst stream characterized by
few tributaries, surface drains,
predominant subsurface drainage,
closed depressions, sinking streams, in-
stream ponors…

19. Hydrogeology
Indications of Two
Groundwater
Systems
It was necessary to pressure
grout the curtain which
could only be accomplished
by reducing aquifer
pressures through a series of
relief wells.

20. Hydrogeology
Indications of Two
Groundwater
Systems
“When the pressure relief wells
were opened to provide for
grout injection, there was an
immediate response in wells
MW-3 and MW-6.”

22. Hydrogeology
Indications of Two
There is an upwelling zone in
Groundwater the standing water of the
WQIZ;
Systems
Water jets out of seams/cracks
in the standpipes of capped
wells in the WQIZ with 15-ft
high standpipes;
Water rose to a height 48 ft
above the quarry floor during
grouting
Grout and rock fragments were
ejected from pressure relief
wells

23. Indications of Two Unconfined zone wells did
MW-1
not respond to the operation
Groundwater of pressure relief wells
Systems PADEP-06
MW-4
MW-2
West quarry
MW-8
inflow zone PADEP-03
PADEP-04
MW-6R
MW-3
PADEP-05
PADEP-01
PADEP-02

24. Indications of Two Hydrogeology
MW-1
Groundwater
Systems PADEP-06
MW-4
MW-2
West quarry
MW-8
inflow zone PADEP-03
PADEP-04
MW-6R
Unconfined zone wells
responded to precipitation
MW-3 and stream flow.
PADEP-05
PADEP-01
PADEP-02

26. Indications of Two Hydrogeology
Groundwater
Systems
Temperatures of unconfined
zone groundwater followed
stream water temperatures
through the fall-winter
months. Confined zone
groundwater remained
nearly constant.

28. Indications of Two Hydrogeology
Groundwater
Systems
Unconfined groundwater
has remained unaffected
over a period of time during
which the volume of quarry
extraction increased.

30. Indications of Two Hydrogeology
Groundwater
Systems
Buzzi does not pump
groundwater.
The water in the WQIZ
flows freely upward into the
stilling basins and it is
pumped from those ponds
to the Bushkill

31. Indications of Two Hydrogeology
Groundwater
Systems
In other words, there is no
active hydraulic influence
pulling water against the
prevailing hydraulic
gradient.

32. Indications of Two Hydrogeology
Groundwater
Systems
After 19 years of artesian
flow into the WQIZ under
significant hydraulic
pressure, there has been no
adverse effect on aquifer
performance.

33. Indications of Two Hydrogeology
Groundwater
Systems
The flows into the WQIZ do
not exert a hydraulic
influence on either
unconfined groundwater or
the Bushkill Creek.

34. Hydrogeology
Absence of responses in unconfined
groundwater to confined zone stresses
– especially in interposed wells

36. Beginning of influent Explanation
Hydrogeology stream conditions
Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
Outcrop of
Jacksonburg Fm
The geology imparts a significant
Ob Beekmantown
directional anisotropy to the Group
Ojb
groundwater system. Groundwater
Flow
D U

37. Hydrogeology MW-1
East Sump
(drained)
PADEP-06
MW-2
‘V’ Sump MW-4
South Sump
West quarry
MW-8
inflow zone PADEP-03
PADEP-04
MW-6R
MW-3
PADEP-05
PADEP-01
PADEP-02

38. Quarry Deepening
Currently approved for deepening to 0 ft msl
from current floor at 100 ft msl. October 3,
2011 report addressed Special Condition 22
for hydrogeology and highwall integrity.
Concern regarding hydrology is that further
deepening could have impact on local
hydrogeology.
Conducted a hydraulic test in June 2011
using south sump.

39. Quarry Deepening
West Quarry Inflow Zone
Proposed mine deepening area

40. MW-1
Quarry Deepening
Sump
MW-4
MW-2
MW-8
Quarry Deepening
MW-3
MW-6R
The sump was dewatered at a rate of
1,800 gpm in July, 2011 – local effects
were monitored in perimeter wells.

41. MW-1
Quarry Deepening
Sump
MW-4
MW-2
MW-8
Quarry Deepening
MW-3
MW-6R
The drawdown of unconfined water
within the sump was ~ 12 ft.
The volume of water extracted was
approximately 4 X 106 ft3 (30 million
gallons). At a porosity of 4% (high) and
an aquifer thickness of 100 ft, that is
equivalent to the storage over an area
of ~ 24 acres.

43. MW-1
Quarry Deepening
Sump
MW-4
MW-2
MW-8
MW-3
Quarry Deepening
MW-6R
Sump rebound was at a rate of 0.15 ft hr-1.
Total rebound was 11.5 ft over a 7-day
recovery period.
The calculated Darcian hydraulic
conductivity is 2 ft day-1 to 4 ft day-1.

44. MW-1
Quarry Deepening
Sump
MW-4
MW-2
MW-8
Quarry Deepening
MW-6R
There were NO responses in any well to
MW-3
either the dewatering at 1,800 gpm or
to the post-extraction recovery…
Except MW-3 which is along-strike of
the sump.

45. MW-1
Quarry Deepening
Sump
MW-4
MW-2
MW-8
MW-6R
MW-3

46. MW-1
Quarry Deepening
MW-4
MW-2
MW-8
MW-3 The structural geology imparts are
MW-6R
pronounced, along-strike directional
anisotropy along a generally SW-NW
direction.
.

47. MW-1
Quarry Deepening
MW-4
MW-2
MW-8
The structural geology imparts a cross-
MW-6R
strike barrier to flow and even to
MW-3
hydraulic communication. .
.

48. Cross-Strike
Cross-Strike

49. The directional anisotropy is
also the condition within the
confined aquifer

50. MW-1
Quarry Deepening
MW-4
MW-2
MW-8
MW-3 As a result of the directional
MW-6R anisotropy, drawdown of the
unconfined aquifer to accommodate
mining to 50 ft msl will be in an along-
strike direction and will be bound by
the north and south boundary faults.
.
The Bushkill in the along-strike
direction is a perched stream
unconnected to groundwater and is
already lined

51. MW-1
Quarry Deepening
MW-4
MW-2
MW-8
MW-3
MW-6R With a footprint area of ~ 50 acres and a
depth of 50 ft, the dewatering can be
maintained with an extraction rate of
~2,600 gpm for a total daily volume of ~
2.6 MGD.
.

52. Quarry Deepening
Highwall Integrity/Stability

53. Quarry Deepening
Two Distinct Structural Trends

54. Quarry Deepening

55. Quarry Deepening

57. Quarry Deepening

60. Quarry Deepening
The Markland Analysis revealed that there are
areas along the southern highwall where
instabilities could occur, but that the potentially
causal structural features do not extend vertically
beyond one bench or only marginally into the next
highest bench.
Routine mitigation measures are adequate to
stabilize the potentially unstable zones

61. Conclusions
There are two hydraulically distinct aquifers:
• a shallow unconfined zone which occurs
predominantly in the epikarst zone;
• a deep confined aquifer which is the principal
source of WQIZ inflow water

62. Conclusions
The pattern of unconfined aquifer dewatering is
controlled by geologic structure. The cone of
depression appears to be elongate in a SW-NE
ellipse, constrained between faults which create
no-flow boundaries to cross-strike flow.

63. Conclusions
Mining to el. 50 ft msl will have little impact on
local or regional water resources.
Using data from sump dewatering test, the east pit
dewatering will require ~ 2,000 gpm, or an
additional 2.5 MGD….
… an increase of 4% to 5% above current
discharge.

64. Beginning of influent Explanation
Conclusions stream conditions
Prominent Karst
Feature
Ojb Ojb
Surface
Expression of
Karst trend
Fold
West quarry axis
inflow zone
Fault
Trace
Fault Inferred
Location
Bushkill
Ob Ob Creek
Ob Geologic
Contact
The speculation that there could be Outcrop of
Jacksonburg Fm
a “conduit of large conductivity” is Ob Beekmantown
Group
inconsistent with all data and
Ojb Groundwater
Flow
observations.
D U

65. Conclusions
MW-4
MW-2
MW-8
The source of WQIZ water is
MW-3 not the Bushkill Creek
MW-6R
In 2009 the loss of water from the Bushkill
increased from 30 MGD to ~38 MGD with
no change to the rate or volume of WQIZ
inflows.
. It is not possible that a portion of water
lost to swallow holes could travel in the
unconfined aquifer away from the quarry
while the remainder flows toward the
quarry.

66. Conclusions
MW-4
MW-2
MW-8
The source of WQIZ water is
MW-3
MW-6R
not the Bushkill Creek
Groundwater elevations in the two aquifers
within the Bushkill Corridor are similar –
at some locations, are under a negative
pressure gradient at some locations, and at
some locations there is a positive pressure
. gradient.