20080868 Ver 2_Report_20081201

TEXASGULF, INC.
LEE CREEK MINE
EVALUATION OF THE EFFECTS FROM
DEWATERING OF THE SHALLOW-AQUIFER SYSTEM
ON THE WATER TABLE AQUIFER AND
IMPLICATION FOR IMPACTS ON WETLANDS
Prepared for:
TEXASGULF, INC.
January 1990
ulft[qM909
1E C 1 2008
WETLANDS ANDSTORMW TE BRANCH
Prepared by:
LEGGETTE, BRASHEARS & GRAHAM, INC.
Professional Ground-Water Consultants
10014 North Dale Mabry Highway, Suite 205
Tampa, Florida 33618
LEGGETTE, BRASHEARS & GRAHAM, INC.
TEXASGULF, INC.
LEE CREEK MINE
EVALUATION OF THE EFFECTS FROM
DEWATERING OF THE SHALLOW-AQUIFER SYSTEM
ON THE WATER TABLE AQUIFER AND
IMPLICATION FOR IMPACTS ON WETLANDS
TABLE OF CONTENTS
TITLE
SUMMARY . . .
INTRODUCTION.
Shallow-Aquifer Dewatering System. . . . . . .
Existing Ground-Water Withdrawal Permits . . .
HYDROGEOLOGY OF THE CHANNEL STRUCTURE . . . . . . .
Deposits of the Post-Croatan and Croatan
Aquifers . . . . . . . . . . . . . . . . . .
Channel Structure Units of the Croatan Aquifer
Shallow Aquifer Ground-Water Monitoring System
54-Day Croatan Aquifer Pumping Test. . . . . .
HISTORICAL DEWATERING ACTIVITIES. . . . . . . . . .
LONG-TERM TESTING OF THE DEWATERING SYSTEM. . . . .
Rainfall and Regional Water-Level Trends . . .
Evaluation of CSU Pumping Effects on the
Croatan Aquifer . . . . . . . . . . . . . . .
Evaluation of CSU Pumping Effects on the
Water Table . . . . . . . . . . . . . . . . .
Evaluation of Wellpoint Pumpage on the
Water Table . . . . . . . . . . . . . . . . .
Projected Pumpage from the Wellpoint System. .
PROJECTION OF CROATAN AQUIFER DEWATERING EFFECTS
ON THE WATER TABLE . . . . . . . . . . . . . . . .
Pumping Scenario 1 . . . . . . . . . . . . . .
Pumping Scenario 2 . . . . . . . . . . . . . .
MINE BENCH DEWATERING WELLS . . . . . . . . . . . .
Estimated Pumpage and Projected Effects from
the Mine-Bench Dewatering System . . . . . .
CONCLUSIONS . . . . . . . . . . . . . . . . . . . .
REFERENCES . . . . . . . . . . . . . . . . . . . . .
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L.EGGETTE, BRASHEARS & GRAHAM, INC.
TEXASGULF, INC.
LEE CREEK MINE
EVALUATION OF THE EFFECTS FROM
DEWATERING OF THE SHALLOW-AQUIFER SYSTEM
ON THE WATER TABLE AQUIFER AND
IMPLICATION FOR IMPACTS ON WETLANDS
TABLE OF CONTENTS (Continued)
LIST OF TABLES
(at end of report)
TABLE TITLE
1 RESULTS OF 54-DAY PUMPING TEST
2 WATER-LEVEL SUMMARY FOR 54-DAY PUMPING TEST
LIST OF FIGURES
(at end of report)
FIGURE TITLE
1 GENERAL LOCATION MAP
2 LOCATION OF CHANNEL STRUCTURE
3 GEOLOGIC CROSS-SECTION OF THE CHANNEL STRUCTURE
4 IDEALIZED HYDROGEOLOGIC CROSS-SECTION
5 PUMPING TEST LOCATION
6 CSU WATER-LEVEL ELEVATIONS ON JULY 8, 1987
7 SHALLOW AQUIFER WELL SYSTEM
8 TYPICAL WELL CONSTRUCTION-OVERBURDEN WELLPOINT
9 TYPICAL WELL CONSTRUCTION-CHANNEL SAND WELL
10 TYPICAL WELL CONSTRUCTION-WATER TABLE MONITOR
WELL
11 54-DAY TEST-DRAWDOWN PLOT FOR WT-1
12 54-DAY TEST-DRAWDOWN PLOT FOR CSU-4
13 CSU AND WELLPOINT SYSTEM PUMPAGE
LEGGETTE, BRASHEARS & GRAHAM, INC.
TEXASGULF, INC.
LEE CREEK MINE
EVALUATION OF THE EFFECTS FROM
DEWATERING OF THE SHALLOW-AQUIFER SYSTEM
ON THE WATER TABLE AQUIFER AND
IMPLICATION FOR IMPACTS ON WETLANDS
TABLE OF CONTENTS (Continued)
LIST OF FIGURES (Continued)
(at end of report)
FIGURE TITLE
14 LONG-TERM HYDROGRAPHS CSU-4 AND WT-1
15 CSU WELLPOINT SYSTEM PUMPAGE DURING OCTOBER
THROUGH DECEMBER, 1989
16 PRECIPITATION AT LEE CREEK MINE
17 HYDROGRAPHS FOR WELLS WT-4 AND CSU-8
18 CSU WATER-LEVEL ELEVATIONS ON OCTOBER 19, 1989
19 CSU DRAWDOWN CONTOUR MAP-NOVEMBER 13, 1989
20 WATER TABLE CONTOUR MAP-OCTOBER 19, 1989
21 WATER TABLE CONTOUR MAP NOVEMBER 13, 1989
22 WATER TABLE DRAWDOWN CONTOUR MAP NOVEMBER 13,
1989
23 HYDROGRAPHS FOR WELLS WT-5 AND CSU-15
24 PROJECTED CSU WELLS, 2.8 MGD
25 CALCULATED DISTANCE DRAWDOWN PLOT FOR CSU AND
WATER TABLE
26 PROJECTED CSU WELLS, 4.3 MGD
APPENDICES
APPENDIX
A ARDAMAN & ASSOCIATES REPORT
B HYDROGRAPHS
LEGGETTE, BRASHEARS & GRAHAM, INC.
TEXASGULF, INC.
LEE CREEK MINE
EVALUATION OF THE EFFECTS FROM
DEWATERING OF THE SHALLOW-AQUIFER SYSTEM
ON THE WATER TABLE AQUIFER AND
IMPLICATION FOR IMPACTS ON WETLANDS
SUMMARY
Texasgulf, Inc. Is (TGIIs) Lee Creek Mine operates
an extensive tiered dewatering system in the overburden
in order to maintain safe mining conditions. The well-
point pumping system is utilized to dewater the
overburden in advance of overburden removal by bucket-
wheel excavator. The Channel Sand Unit (CSU) pumping
system is utilized to pump from the underlying CSU to
dewater the unit in advance of mining by dragline.
Presently, the mine is permitted (Permit 38A-1) to
pump 1.0 million gallons per day (mgd) from both
dewatering systems. Temporary Permit No. 72 (which was
issued for testing purposes) allows the mine to pump an
additional 1.2 mgd from both systems. Historical pumpage
from the wellpoint system has averaged about 0.3 mgd and
about 0.7 mgd from the CSU system.
Testing of both dewatering systems was undertaken
by TGI in October, 1989 to determine pumping effects on
the water table in the area east of North Carolina Route
306 (Route 306). Results of the testing showed that
there is a perched zone that occurs within a few feet of
land surface, a water-table aquifer with water levels
approximately 5 to 10 feet below land surface, and the
CSU artesian water levels that occur approximately 10 to
20 feet below land surface. The CSU is overlain (in
ascending order) by the Shell Bed, the Sugar Sand or
Croatan Clay, the Gumbo Clay, Post-Croatan Sand, Farmers
Clay and surficial soils. The units beneath the top of
the Croatan Clay or at some locations beneath the top of
LEGGETTE, BRASHEARS & GRAHAM, INC.
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the Sugar Sand form the Croatan aquifer. The top of the
Yorktown Clay forms the basal confining unit of the
Croatan aquifer. Units above the top of the Croatan Clay
and Sugar Sand form the Post-Croatan aquifer. The Shell
Bed occurs throughout the mine area in a blanket like
manner and forms the mine bench.
Water levels of the perched zone are not
significantly affected by pumpage from the CSU. Water-
table levels respond to pumping from the CSU. A decline
of about 2.5 feet in the water table was observed
approximately 1,500 feet from the center of pumpage after
approximately 44 days of dewatering.
Evaluation of pumping effects indicates that the
canal system inhibits the drawdown in the perched water
table and in the water table. Furthermore, when the
canals are excavated through the Farmers Clay and into
the underlying sand unit the canals are effective at
recharging the hydraulic systems. While the canals
mitigate dewatering impacts on the perched zone and water
table, they hamper dewatering efforts.
Review of historical water levels and simplified
dewatering projections indicate it will be necessary to
pump approximately 3 to 4 mgd from the CSU in advance of
the mine. An additional pumpage of 2 to 3 mgd from the
CSU is required utilizing wells located on the mine bench
once the overburden has been removed to the Shell Bed.
This water is derived from the Croatan aquifer. A
withdrawal of approximately 1 to 3.5 mgd is also required
to be pumped from the overburden in advance of the
bucket-wheel excavator. This water is derived from the
Post-Croatan aquifer. The purpose of both dewatering
systems is to maintain safe mining conditions.
Analysis indicates that pumping approximately 4 mgd
from the CSU would result in about 10 to 15 feet of
water-table decline in the vicinity of the mine.
LEGGETTE, BRASHEARS & GRAHAM, INC.
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Additional water-table drawdown outside the mine block
would be caused by overburden removal by the bucket-wheel
excavator. Approximately 5 feet of additional water-
table drawdown would be observed at a distance of 500
feet from the mine due to overburden removal. The
perched zone would not be affected significantly by
pumping from the CSU or overburden removal.
The wellpoint pumpage does not affect water-table
levels more than 400 to 600 feet from the line of
wellpoints. The effects on the perched zone would be
insignificant.
i
The water quality of the Post-Croatan and Croatan
aquifers, as determined primarily by chloride
concentrations, has not been affected by dewatering
activities.
LEGGETTE, BRASHEARS & GRAHAM, INC.
-4-
INTRODUCTION
Leggette, Brashears & Graham, Inc. (LBG) was
requested by Texasgulf, Inc. (TGI) to determine effects
on ground-water levels caused by pumping from the
shallow-aquifer system in the area of Mine Block 20.
The State of North Carolina Department of Environmental
Management (NCDEM) expressed concern as to the potential
effects on the "wet area" located east and northeast of
Mine Block 20. TGI must pump from the shallow-aquifer
system in order to maintain safe conditions during
overburden removal and mining of the ore body.
The "wet area" that the state has expressed concern
has been modified by previous pre-mining activities. The
North Carolina Phosphate Company burned off all of the
trees and plowed the remaining vegetation under. The
area was then ditched to allow for drainage of ground
water from the area. Ownership of the property was later
transferred to TGI.
Shallow-Aquifer Dewatering System
Dewatering of the shallow aquifer is accomplished
by a two tiered pumping system. The upper tier consists
of wellpoint systems that are utilized to dewater the
Post-Croatan aquifer to a maximum depth of about 25 to
30 feet below land surface (bls) in advance of overburden
removal by bucket wheel excavator. This water is derived
from the Post-Croatan aquifer.
The lower tier of dewatering wells are utilized to
pump from the Channel Sand Unit (CSU) to control ground-
water inflow from the CSU during overburden removal by
dragline. These wells are located around the perimeter
of the mine block or on the Shell Bed. The water is
derived from the Croatan aquifer.
UGGETTE, BRASHEARS & GRAHAM, INC.
-5-
TGI is presently pumping an average of approximately
0.3 million gallons per day (mgd) from the Post-Croatan
aquifer and about 0.7 mgd from the Croatan aquifer for
a combined withdrawal of approximately 1 mgd from the
shallow-aquifer system.
Existing Ground-Water Withdrawal Permits
Two existing permits issued by the NCDEM presently
regulate withdrawals from the shallow-aquifer system.
Permit No. 38A-1 was transferred from the North Carolina
Phosphate Company and allows for pumpage of up to 1.0 mgd
from the overburden. Temporary Permit No. 72 allows for
an additional withdrawal of 1.2 mgd from the overburden.
Permit No. 72 was issued by the NCDEM to allow for long-
term testing of the shallow-aquifer system. The purpose
of the testing was to determine if "wet areas" would be
negatively impacted by dewatering activities.
The results of this testing and analysis of
historical water levels, pumpage and water quality are
the basis of this report. The report is submitted in
support of TGI's request for additional withdrawals from
the shallow-aquifer system to allow continued safe mining
operations. Any additional pumping granted by the NCDEM
would be primarily from the CSU and not from the water-
table aquifer.
HYDROGEOLOGY OF THE CHANNEL STRUCTURE
The geology of the unconsolidated deposits in the
area of the mine and of the channel structure have been
mapped in detail by TGI. Figure 1 shows the general
location of the current TGI mining operations. Figure
2 shows the thickness of the channel structure in the
vicinity of the current mining blocks.
UGGETTE, BRASHEARS & GRAHAM, INC.
-6-
As shown on Figure 3, the shallow-aquifer system in
the mine area is divided into two aquifers. The upper
aquifer is designated the Post-Croatan aquifer and is
composed of units from the water table to top of the
Croatan Clay Unit, or at some locations to the bottom of
the Sugar Sand Unit. The Post-Croatan aquifer includes
the water-table aquifer.
The Croatan aquifer is composed of unconsolidated
deposits that extends from the top of the Croatan Clay,
or top of the Sugar Sand Unit, to the top of the Yorktown
Clay. This aquifer includes the CSU.
Deposits of the Post-Croatan and Croatan Aquifers
The Post-Croatan aquifer is composed of the units
above the Croatan Clay or Sugar Sand Unit. These units
are unconsolidated fine to very-fine grained sand and
clayey-sand with interlayered clay and sandy-clay units.
The cross-section in Figure 3 shows the units which
comprise the Post-Croatan aquifer.
The Post-Croatan aquifer consists of 2 to 3 feet of
surficial organic sandy-clay underlain by 7 to 10 feet
of sandy-clay and clayey-sand. The sandy-clay/clayey-
sand unit forms a continuous semi-confining unit
throughout the area of the mine. The unit has been
designated by TGI as the Farmers Clay.
The Farmers Clay causes a perched zone in some
areas. Beneath the Farmers Clay are interbedded clay and
blue-gray fine sand units that consist of variable
percentages of each component. The unit ranges in
thickness from 4 to 14 feet. Some of these units are
continuous throughout the area of the mine and some grade
laterally into other units. The interbedded clay and
sand units are underlain by the Gumbo Clay.
The Gumbo Clay forms a second semi-confining unit
within the Post-Croatan aquifer that separates the water-
LEGGETTE, BRASHEARS & GRAHAM, INC.
-7-
table and overlying perched zone from the CSU. The Gumbo
Clay is underlain by either a fine to very-fine sand
termed the Sugar Sand Unit or the Croatan Clay which are
part of the Croatan aquifer. Laterally the Sugar Sand
changes in composition and grades or interfingers into
the Croatan Clay.
The Croatan Clay varies in thickness from 0 to 22
feet and is discontinuous. Where this unit is areally
extensive, its upper contact forms the basal semi-
confining unit of the Post-Croatan aquifer and separates
the CSU from the water table and from the perched zone.
The Croatan Clay, Sugar Sands, Shell Bed and CSU form the
Croatan aquifer.
Figure 4 is a hydrogeologic cross-section that shows
the ground-water system in the area of the mine. A
perched zone occurs in the organic sandy clay above the
Farmers Clay. The Post-Croatan aquifer is a phreatic
aquifer with water levels that naturally occur 5 to 10
feet bls and extends to the top of the Croatan Clay or
to the top of the Sugar Sand. The Post-Croatan aquifer
is approximately 30 to 32 feet thick and contains two
intermediate semi-confining units and, at some locations,
a basal semi-confining unit. Water-levels occur several
feet below the top of the Farmers Clay.
Vertical permeability values were determined by
Ardaman & Associates, Inc. (1989) through laboratory
testing of undisturbed soil samples collected during
performance of a soil boring at Well WT-4. A copy of
this report is enclosed in Appendix A. Laboratory
testing showed that sandy units of the Post-Croatan
aquifer have vertical permeabilities that range from 254
gallons per day per square foot (gpd/ft') (1.2x10-'
centimeters per second (cm/sec)) for the Sugar Sand to
16 gpd/ft' (7.6x104 cm/sec) for the upper blue-gray Post-
Croatan sand unit. The horizontal permeabilities would
LEGGETTE, BRASHEARS & GRAHAM, INC.
-8-
be about an order of magnitude higher than the vertical
permeabilities.
The vertical permeabilities of the semi-confining
units were also determined by Ardaman (1989). The
Farmers Clay has a vertical permeability that ranged from
0.042 gpd/ft2 (2.0x10-6 cm/sec) to 0.020 gpd/ft2 (9.4x10
7 cm/sec). The Gumbo Clay has a vertical permeability of
1.21 gpd/ft2 (5.7x10-5 cm/sec). A check of these values
can be made by multiplying the leakance value derived
from the 54-day pumping tests (2.3x103 gpd/ft3) by the
thickness of the Farmers Clay (approximately 10 feet).
This calculation yields a vertical permeability of 0.023
gpd/ft2 (1.1x10-6 cm/sec) which compares favorably with
the laboratory results. The pumping test is discussed
later in the report.
The regional direction of ground-water flow is
controlled by the location of mined-out blocks and
natural discharge sources such as creeks and rivers.
The Post-Croatan aquifer is not presently utilized
for water supply in the vicinity of the current mining
operations. A few small diameter wells may withdraw
limited amounts of water from the system for domestic
use in some areas.
Channel Structure Units of the Croatan Aquifer
The channel structure is a regional scour feature
that was eroded into the Yorktown Clay. The isopach
contours on Figure 2 represent the combined thickness of
both the CSU and the Shell Bed unit. The CSU and Shell
Bed have a combined thickness of approximately 40 to 50
feet along the axis of the channel structure. The CSU
thins and eventually pinches out along the flanks of the
structure. This channel structure is approximately 5,500
feet wide. The Shell Bed is continuous throughout the
area of the mine and is utilized as the mine bench for
LEGGETTE, BRASHEARS & GRAHAM, INC.
-9-
the draglines. The CSU and Shell Bed are the primary
water bearing units of the Croatan aquifer.
The geologic units of the channel structure are
shown on Figure 3. The CSU is composed predominately of
a mixture of very-coarse quartz sand and fine shell-hash.
It is overlain by the Shell Bed and underlain in most
places by the Yorktown Clay. The Shell Bed ranges in
thickness from about 5 to 12 feet and averages about 10
feet in thickness along the axis of the channel
structure. The CSU is underlain by the Channel Mud Unit
(Channel Mud), the Channel Hash Unit (Hash Unit) and the
Yorktown Clay. The Channel Mud and the Hash Unit are
absent along the flanks of the channel structure. The
Yorktown Clay forms the lower confining unit while the
clay units in the Croatan Clay or Gumbo Clay form the
upper semi-confining units.
The upper contact of the CSU occurs at depths of
about 38 to 45 feet bls and the unit extends to depths
of about 70 to 80 feet (including the Channel Mud and
Hash Unit). The CSU varies in thickness from 30 to 40
feet along its axis to 0 feet where it pinches out along
the flanks of the channel structure. The CSU, the Shell
Bed, the Channel Mud and the Hash Unit represent a single
hydraulic unit that is about 40 to 50 feet thick along
the axis. Under natural conditions, the Croatan aquifer
is a semi-confined aquifer with about 30 feet of artesian
pressure.
Results of a preliminary 24-hour pumping test
conducted at the location shown on Figure 5 indicated a
horizontal permeability for the CSU of approximately 330
gpd/ft2; an apparent transmissivity of approximately
10,000 gallons per day per foot (gpd/ft); a storage of
3.0x10-4; and a leakance of 4. Ox1O_3 gallons per day per
cubic foot (gpd/ft3).
LEGGETTE, BRASHEARS & GRAHAM, INC.
-10-
A 54-day duration pumping test was performed in July
and August, 1987 at the location shown on Figure 5.
Results of this test yielded an average horizontal
permeability of 662 gpd/ft2; an apparent transmissivity
of about 16,000 gpd/ft; a storage of 5.4x104; and a
leakance of 2.3x103 gpd/ft3. Hydraulic properties
calculated from the 54-day test are shown on Table 1.
The test is discussed in detail later in this report.
The direction of ground-water flow varies with
mining activities and pumping. Figure 6 shows the water-
level elevations on July 8, 1987. At that time, Mine
Block 16 had been excavated of overburden down to the
Shell Bed and mining of the ore was occurring in the
southern corner of the mine block. Ground-water flow in
the CSU was toward the sump which was excavated into the
Shell Bed to allow for drainage of the Shell Bed and
removal of seepage water. Monitoring of water levels in
the CSU after activation of the dewatering system has
shown that the direction of flow is controlled primarily
by the CSU dewatering system, the location of mined-out
areas, and the proximity of the wells to where the
overburden has been removed.
Water levels in the CSU under static conditions in
July, 1987 were approximately 10 feet bls or about 30
feet above the upper contact of the CSU. Water levels
in the Shell Bed were at approximately the same elevation
as those in the CSU. This suggests that the CSU and
Shell Bed are hydraulically connected and behave as a
single hydraulic unit.
Comparison of water-table elevations to CSU water-
level elevations show approximately 5 feet of downward
head from the water table to the CSU under natural
conditions. This amount of head difference indicates
that a significant semi-confining layer(s) separates the
water table from the CSU.
LEGGETTE, BRASHEARS & GRAHAM, INC.
-11-
TGI performed a well inventory of the area around
the TGI property to identify potable wells belonging to
other parties which utilized the CSU for water supply.
No wells were identified during the inventory.
Shallow Acauifer Ground-Water Monitoring System
TGI began construction of an extensive ground-water
monitoring network for the shallow-aquifer system in
1986. Water levels, pumpage and water quality are
monitored by TGI staff. Figure 7 shows the location of
the Post-Croatan aquifer and Croatan aquifer wells.
The Post-Croatan aquifer water levels and pumpage
from the wellpoint system are monitored by TGI. Wells
WT-1 through WT-5 are utilized to monitor water-table
levels. The wells are typically 15 feet deep with 7 feet
of screen.
The wellpoint system is utilized to dewater the
Post-Croatan aquifer in advance of the bucket-wheel
excavators during overburden removal. The wellpoint
system monitoring wells are utilized to determine pumping
effects. Both pumping and monitoring wells are typically
30 feet deep. The OBMW wells (Overburden Monitoring
Wells) are utilized to determine pumping effects from the
North-South line of wellpoints. The PF (Pit Face) series
wells are utilized to determine pumping effects from the
East-West line of wellpoints. Both series of wells can
be utilized to determine effects of the excavated mine
blocks on the water table.
Wells CSU-1 through CSU-15, 23-85, A-25, B-25, B-
50, monitor water levels in the CSU. Pumpage and water
levels are monitored in Channel Pumping Wells (CPW) 21
through 37. Well SB-1 monitors levels in the Shell Bed
and Well CHU-1 monitors water levels in the Hash Unit.
The CSU wells are generally approximately 70 feet deep
LEGGETTE, 6RASHEARS & GRAHAM, INC.
-12-
with 20 to 40 feet of screen. Well CSU-3, CSU-4, WT-1,
SB-1 and CMU-1 have been abandoned.
Figures 8 through 10 show the typical well
construction and the units from which water is withdrawn
or monitored for each type of well.
54-Day Croatan Aquifer Pumping Test
Results of the 54-day pumping test performed in
July, 1987 indicated that the water table was drawn down
by pumping from the CSU. Wells CTW-1 and CTW-2 were
pumped at 125 gallons per minute (gpm) and 150 gpm
respectfully, for a period of 54 days. The pumping wells
are spaced 230 feet apart and withdraw water from the
CSU. A summary of water levels measured during the test
are shown in Table 2.
The well cluster located 535 feet southeast of the
pumping center included three wells; these are CSU-4,
SB-1 and WT-1. After 23 days of pumping, the maximum
drawdowns were observed when the combined pumping rate
temporarily reached 315 gpm. Maximum drawdowns in the
pumping wells ranged from 44.79 feet to 46.00 feet for
CTW-1 and CTW-2, respectively. The maximum drawdown at
CSU-4 was 9.26 feet; at SB-1 was 9.33 feet; and at WT-1
was 5.50 feet.
After 54 days of pumping at an average combined rate
of 275 gpm, the drawdown at CTW-1 was 31.84 feet; at CTW-
2 was 37.00 feet; at CSU-4 was 8.40 feet; at SB-1 was
8.00 feet; and at WT-1 was 3.40 feet. Table 2 summarizes
the pumpage and water-level measurements obtained from
the 54-day test.
The test also showed that the water table is
strongly affected by rainfall, as would be expected.
The time-drawdown graph for WT-1 for the 54-day test (on
Figure 11) shows that the apparent drawdown in the water
table decreased from around 4 feet after about 35 days
LEGGETTE, BRASHEARS & GRAHAM, INC.
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of pumping to 0.42 feet at 43 days of pumping. This
water-level change coincided with rainfall that occurred
from August 5 through August 19, 1987. By the end of the
test the apparent drawdown had again increased to
approximately 4 feet.
Apparent drawdown at CSU-4 (Figure 12) varied only
by approximately 1 foot during this same period. This
is an indication of the degree of hydraulic separation
between the water table and the CSU and that the water
table is more strongly affected by precipitation.
HISTORICAL DEWATERING ACTIVITIES
Dewatering activities of the Croatan aquifer were
begun in mid-1988 and continued for a few months at an
average rate of approximately 0.5 mgd. The CSU pumping
wells were located along the north side of Mine Block 20.
Pumpage from the Post-Croatan aquifer was initiated in
late 1988 in Mine Block 20 and pumpage averaged about 0.2
mgd. Figure 13 shows the historical pumpage from the
shallow-aquifer dewatering system.
Figure 14 shows historical water levels in Wells
CSU-4 and WT-1. The hydrographs are approximately
coincidental. They show that although water levels in
both systems respond to pumping from the CSU, the CSU
water levels declined nearly 5 feet more than did the
water table during the 54-day test.
In March, 1988, TGI began pumping the dredge water
from Mine Block 17. The pumping caused water levels in
the CSU at Well CSU-4 to decline from about 4 feet above
mean sea level (msl) to -14 feet (msl) or about 18 feet
of water-level decline. The water table at WT-1 is
estimated to have declined about 5 feet during the same
period of time.
LEGGETTE, BRASHEARS & GRAHAM, INC.
-14-
As shown on Figure 14, water levels in both the CSU
and water table increased throughout 1989 when pumping
ceased in Mine Block 17. In addition, it is believed
that water levels in both systems increased as a result
of rerouting of a deep well toward the well cluster. The
deep well canals are excavated through the perched zone
and the Farmers Clay allowing the canals to recharge the
Post-Croatan aquifer.
LONG-TERM TESTING OF THE DEWATERING SYSTEM
In October, 1989, TGI undertook long-term testing
of the dewatering system to determine the effects on the
"wet areas" east of Route 306. The purpose of this
testing was to evaluate the impacts on the ground-water
system in that area.
Controlled testing of the two tiered dewatering
system began on October 25, 1989. Figure 15 shows the
pumpage from the CSU and wellpoint system for the period
of the test. Pumpage from the CSU averaged 0.67 mgd (463
gpm) from 11 to 17 CSU pumping wells. Each well produces
an average of about 30 gpm. The maximum pumpage from the
CSU occurred on December 26, 1989 when the daily pumpage
was 0.88 mgd (611 gpm).
Pumpage from the Post-Croatan aquifer utilizing the
wellpoint system averaged 0.31 mgd (218 gpm) from
approximately 50 to 90 wellpoints. Each wellpoint
yielded an average of about 3.2 gpm. The maximum pumpage
occurred on December 17, 1989 when 91 wellpoints were
pumped at 0.43 mgd (301 gpm).
Rainfall and Regional Water-Level Trends
Hydrographs for CSU monitoring wells, CSU pumping
wells and Post-Croatan aquifer monitoring wells are
contained in Appendix B. Figure 16 shows rainfall for
LEGGETTE, BRASHEARS & GRAHAM, INC.
-15-
the period of the test as monitored at the mine. As
shown on the figure, a large percentage of the total
rainfall during the test occurred from December 8 through
December 20, 1990. Comparison on the hydrographs in
Appendix B with Figure 16 shows that increases in ground-
water levels coincide with rainfall.
Figure 17 shows the hydrographs for Wells WT-4 and
CSU-8. The wells are located approximately 6,000 feet
northeast of the present center of pumpage and were not
affected by CSU pumpage during the test. The hydrographs
of the wells show regional water-level trends during the
test for the water table and the CSU.
Water levels in the CSU at CSU-8 increased by
approximately 1.6 feet during the test. Water levels
increased in WT-4 approximately 2.6 feet for the same
period. Water levels were not corrected for regional
trends due to the complexities of the hydrogeologic
system and due to the fact that the majority of the
increase occurred late in the test during December. The
water-level trends observed during the test represent
actual conditions that were observed as a result of
pumping and rainfall. If rainfall had not occurred
during this period, the declines in the water table and
CSU would have been greater.
Evaluation of CSU Pumping Effects on the Croatan Aquifer
Figure 18 shows the prepumping (static) water levels
in the CSU on October 19, 1989. The water-level
elevations ranged from 8.62 feet (msl) at CSU-15 to
-28.25 feet (msl) at CSU-14. Well CSU-14 and CSU are
located on the mine bench inside of Mine Block 20
approximately 45 feet below original grade. The regional
direction of ground-water flow is generally northwest
toward the active mine operations in Mine Block 18.
Under nonpumping conditions, flow net analysis indicates
LEGGETTE, BRASHEARS & GRAHAM, INC.
-16-
that there is approximately 0.5 to 0.6 mgd of water
flowing into Mine Block 20 from the CSU. It should be
noted that water-level elevations and drawdown contours
on subsequent maps, particularly in the mined-out areas
and adjacent to the high wall, may be misleading due to
the sparseness of control points.
The actual hydraulic gradients near the mined-out
areas would be much steeper than shown on the diagrams.
Figure 19 shows the apparent drawdown in the CSU on
November 13, 1989. November 13 was chosen because this
was the day following a period of maximum pumpage. From
November 5 through November 12, the CSU was pumped at an
average of 0.78 mgd (544 gpm) and the wellpoint system
was pumped at 0.33 mgd (227 gpm) for a total of 1.11 mgd
(771 gpm).
Apparent drawdown at the CSU pumping wells ranged
from 12 to 30 feet. Apparent drawdown in the CSU
monitoring wells ranged from 0.15 at Well CSU-7 to 26.0
feet at Well CSU-15. Water levels increased by a range
of 0.45 to 0.50 feet at Wells CTW-1, CTW-2, A-50, B-25,
B-50, CSU-4, SB-1, CSU-1, WT-1 and CSU-5.
A new deep well canal was being excavated during the
test from the southeast corner of Mine Block 20 to the
southeast corner of Mine Block 16. Wells SB-1, CSU-4 and
WT-1 were abandoned because they were located in the path
of the canal. The canals are 10 to 15 feet deep with a
water-level elevation of approximately 8 to 9 feet (msl).
Prior to the long-term testing, CSU water-level
elevations in the vicinity of CTW-1 were -8 to -12 feet
(msl). The head differential from the canals into the
CSU ranges from about 16 to 21 feet. The head
differential from the canal to the Post-Croatan aquifer
is about 1.5 to 2.5 feet in the vicinity of WT-1. In
view of the head differentials from the canal to the
water table and CSU, it is likely that water seeping from
LEGGETTE, BRASHEARS & GRAHAM, INC.
-17-
the canal systems into the underlying formations
apparently caused localized mounding in the area of those
wells around CTW-1 and CTW-2.
Evaluation of CSU Pumping Effects on the Water Table
Figure 20 shows the water-table elevations on
October 19, 1989 prior to the test. Water levels ranged
from 11.37 feet (msl) at Well WT-5 to -9.48 feet (msl)
at Well OBMW-5. Ground-water flows from the south and
east towards the excavated mine blocks.
Figure 21 shows the water-table elevations on
November 13, 1989. The water-table configuration and
flow directions are similar to those prior to the start
of the test. The water-table elevations range from 10.37
feet (msl) at WT-5 to -15.30 feet (msl) at OBMW-5.
The configuration of the water table on both
diagrams indicates that the canal system affects the
Post-Croatan aquifer. The contours show effects of
ground-water mounding along the canal near WT-1.
Figure 22 shows the apparent drawdown in water-table
elevations on November 13, 1989. Based on this figure,
it does not appear that the Post-Croatan aquifer was
affected by pumping from the CSU in the area east of
Route 306. The cone of depression centered around Wells
OBMW-1 and OBMW-5 is not entirely accurate since it is
believed that the gradients near the high wall of Mine
Block 20 are much steeper than indicated on the figure.
This means the zone of influence would be less than
indicated on the diagram.
On December 6, 1989, water-table elevations began
to increase, primarily due to rainfall, to near their
pre-test levels. As shown on Figure 23, water levels at
CSU-15 remained depressed even though the water-table
elevation at WT-5 increased to within a foot of its
prepumping level. This indicates the degree of hydraulic
LEGGETTE, 13RASHEARS & GRAHAM, INC.
-18-
separation between the water table and CSU and shows that
pumpage from the CSU has little effect on water levels
in the Post-Croatan aquifer.
Evaluation of Wellpoint Pumpage on the Water Table
Data obtained from the October, 1989 test and
previous historical records indicate the cone of
depression in the Post-Croatan aquifer caused by the
wellpoint system pumpage does not extend outward from the
line of pumping wells more than approximately 600 to 800
feet regardless of the pumpage. Typically, the radius
of influence due to pumping from a water-table aquifer
is limited by recharge and not pumpage.
The majority of decline of water levels in the
overburden monitor wells is attributed to seepage from
the overburden into the mine block during advance of the
bucket-wheel excavator face. Review of the hydrographs
for the overburden wells shows that the combined effect
of the wellpoint pumpage and seepage causes approximately
2 to 3 feet of drawdown in water levels at a distance of
about 200 to 300 feet from the bucket-wheel excavator
face.
Projected Pumuage from the Wellpoint System
As previously stated, the wellpoint systems pump a
maximum of approximately 6 gpm per wellpoint when pumping
is initiated. The yield of the wellpoint declines with
continued pumping to a sustainable yield of approximately
2 gpm per wellpoint. Based on the projected size of the
mine blocks and a wellpoint spacing of about 30 feet, the
required amount of pumpage will range from about a
maximum of 3.5 mgd or 2.6 mgd from 300 to 400 wellpoints.
The long-term sustainable withdrawal probably will be on
the order of 1.2 mgd to 0.8 mgd from 300 to 400
wellpoints. The number of wellpoints utilized in the
LEGGETTE, E3RASHEARS & GRAHAM, INC.
-19-
estimate was obtained from TGI mine plan as of December,
1989. The pumpage estimate assumes that the planned
wellpoint system for each mine block will be operated
simultaneously.
PROJECTION OF CROATAN AQUIFER DEWATERING
EFFECTS ON THE WATER TABLE
A simplified analytical model was utilized to make
projections as to the effects of pumping from the CSU on
the water table in the area of concern east of Route 306.
The model uses the distance -drawdown calculation
method for leaky-artesian aquifers (DeGlee, 1951). The
model also simulates water-table drawdown by calculating
the lowering of the water table due to the increased head
drive between the water table and the calculated steady-
state leaky-artesian drawdowns in the underlying CSU.
The water-table drawdown calculation uses the method
described in Walton (1962) as modified to the expression
below:
WT = (s x L x T) / (7.48 x Sy)
Where: WT = Water-table lowering, in feet;
s = Calculated steady-state
leaky-artesian drawdown, in feet;
L = Leakance coefficient; 0.0023 gpd/ft3
T = Time since steady state conditions
have been reached, 90 days;
Sy = Specific yield (storage) of the
water-table aquifer; 0.20
Although not a true flow model of the water-table
system, this method of coupling the two aquifers has been
shown to be consistent with the results of more
sophisticated models such as the Prickett-Lonnquist
LEGGETTE, BRASHEARS & GRAHAM, INC.
-20-
Aquifer simulation Model (LBG, 1984).
Several pumping scenarios were examined utilizing
the model and are described in the following sections.
Pumping Scenario 1
Pumping Scenario 1 simulated drawdown in the CSU
and water table due to 32 CSU wells pumping at a rate of
60 gpm each for 90 days. A pumping rate of 60 gpm was
chosen because that is the maximum noted pumping rate for
the pumping equipment that TGI utilizes in these wells.
A pumping time of 90 days was chosen because this is
historically about as long as the mine area has gone
without precipitation in the past. The combined
withdrawal rate was 2.8 mgd (1,920 gpm). The wells were
located around the southern and eastern perimeter of Mine
Block 20 as shown on Figure 24. The well spacing was 200
feet.
Results of the model indicate that the drawdown in
the CSU ranges from about 20 to 36 feet at the pumping
wells. CSU drawdown within the mine block ranged from
about 12 to 30 feet.
The distance-drawdown graph shown on Figure 25 was
generated from the drawdown predicted by the model. The
graph shows that there will be about 25 feet of drawdown
in the CSU at a distance of 500 feet east of Mine Block
20 in the "wet area". The cone-of-depression does not
extend more than approximately 4,000 feet east of Mine
Block 20.
The calculated water-table drawdown is presented on
the distance -drawdown graph shown on Figure 25. Drawdown
in the water table was about 8 feet near the CSU pumping
wells located on the east boundary of Mine Block 20. At
a distance of 500 feet east of the pumping wells,
approximately 3 feet of drawdown was calculated. -The
cone-of-depression in the water table extends to
LEGGETTE, BRASHEARS & GRAHAM, INC.
-21-
approximately 4,000 feet from the east side of Mine Block
20.
Pumping Scenario 2
Pumping Scenario 2 projected drawdowns in the CSU
and water table from 50 CSU pumping wells located as
shown on Figure 26. Each well is spaced approximately
200 feet apart and was pumped at 60 gpm for 90 days for
a combined total withdrawal of approximately 4.3 mgd
(3,000 gpm).
Distance-drawdown graphs (generated from the model
results) for this pumping scenario are shown on Figure
25. The distance is measured from the east border of
Mine Block 20 towards the "wet area" east of Route 306.
Drawdown in the CSU ranged from 26 feet to approximately
42 feet across the interior of the mine block.
Approximately 30 feet of drawdown in the CSU is projected
at a distance of 500 feet east of the border of Mine
Block 20. The cone-of-depression extends to about 4,000
feet east of the eastern boundary of Mine Block 20.
Water-table drawdowns ranged from about 13.5 feet
at the CSU wells to about 4.5 feet at a distance of 500
feet east of the eastern border of Mine Block 20. The
cone of depression in the water table does not extend
further than 4,000 feet.
The pumping scenarios examined do not account for
pumpage from the overburden wellpoint system, recharge
from precipitation, seepage from the bucket-wheel
excavator face or recharge from the canal system. Much
of the effect from the wellpoints located on the eastern
border of Mine Block 20 would be mitigated by the deep
well canals. As previously stated, analysis of
hydrographs for the wellpoint monitoring wells show that
the drawdown does not extend more than 600 to 800 feet
from the wellpoint pumping centers.
LEGGETTE, BRASHEARS & GRAHAM, INC.
-22-
MINE BENCH DEWATERING WELLS
Hydrographs for Wells CSU-13 and CSU-14, which are
located on the mine bench (Shell Bed), show that Croatan
aquifer water levels on the mine bench are not
significantly affected by pumping from the CSU wells or
the wellpoint system located in Mine Block 20. The canal
system and the toe ditch and finger ditch system act as
constant-head boundaries that prevent the propagation of
the cone of depression. Seepage of water from the Shell
Bed and CSU during mining operations by the draglines
has the potential to cause unsafe mining conditions.
Therefore, a separate dewatering system will be required
to remediate this situation.
once the overburden has been removed to the top of
the Shell Bed by the bucket-wheel excavators, the CSU is
under water-table conditions with a storage coefficient
of 10 to 100 times higher than when it was semi-confined.
This means that it will take considerably longer to
obtain the same amount of drawdown than it would under
artesian conditions.
Preliminary estimates of pumping effects show that
one well located on the mine bench pumping from the
Croatan aquifer at a rate of 25 gpm for 60 days would
lower CSU water levels by approximately 2.5 feet in the
immediate vicinity of the well. After six months of
pumping the well at 25 gpm there would be approximately
4 feet of drawdown in the immediate vicinity of the well.
Based on this preliminary evaluation, it is recommended
that a pilot dewatering system be constructed on the
Shell Bed. The pilot dewatering system should be
designed to test the yield and impacts from a series of
both 2-inch diameter wellpoints and 4-inch diameter
wellpoints. Several monitoring wells should be
LEGGETTE, BRASHEARS & GRAHAM, INC.
-23-
constructed to determine drawdown at distance for both
pilot tests.
It is believed that the additional pumpage from the
mine-bench dewatering system would not significantly
affect water levels outside of the mine block. The
finger and toe ditch system and the sumps would act as
a constant-head boundaries to prevent the propagation of
the cone of depression outside of the mine blocks. The
hydrographs for Wells CSU-13 and CSU-14 demonstrate this
effect. Water levels in these wells have remained
essentially unchanged during the recent long-term testing
of the existing two-tiered dewatering system.
Although the constant-head boundary conditions would
mitigate off-site pumping effects, they also hamper
dewatering activities. It is recommended that the finger
and toe ditch systems, and the sumps be excavated as deep
as is practical and that the water level in the sumps be
pumped down and maintained at the lowest level possible.
Estimated Pumpage and Projected Effects from the Mine-
Bench Dewatering System
Water withdrawn from the mine bench dewatering
system will be derived from the Croatan aquifer. It is
difficult to accurately predict at this time the volume
of water that must be pumped to control the inflow of
ground water into the mine. A rough estimate has been
made of the amount of water in storage in the Shell Bed
and CSU for the approximate surface area of Mine Block
20. To lower water levels on the order of 25 feet in a
period of 180 days would require pumping at a rate of 2
to 3 mgd. The estimate does not account for surface
runoff and precipitation into the mine block or pumpage
of water from the sumps.
The 2 to 3 mgd estimate applies to initial pumpage.
The required amount of pumpage would decrease with time
as the Shell Bed and CSU are dewatered.
LEGGETTE, DRASHEARS & GRAHAM, INC.
-24-
It is estimated that the following maximum daily
pumpages will be required to dewater.the shallow-aquifer
system.
Post-Croatan Aquifer Pumpage
Wellpoint Pumpage 0.8 to 3.5 mgd
Croatan Aquifer Pumpage
CSU Pumpage
Mine Bench Pumpage
Total Pumpage
2.8 to 4.3 mgd
2.0 to 3.0 mad
5.6 to 10.8 mgd maximum
Water Ouality
Water-quality analysis (primarily chloride
concentrations) have been monitored in water collected
from the CSU and Post-Croatan aquifer dewatering systems.
These results are submitted monthly to the NCDEM. The
concentrations observed are typical of the shallow-
aquifer system.
Evaluation of these concentrations indicate that the
water quality in the shallow-aquifer system has varied
with time but remains essentially unchanged from pre-
dewatering analysis.
CONCLUSIONS
Analyses of historical water levels and pumpage
records and results from dewatering testing indicate that
the water table will be lowered in the area east of Route
306 approximately 10 to 15 feet immediately adjacent to
the east boundary of Mine Block 20 due to pumping from
the CSU. Several additional feet of water-table drawdown
will occur due to seepage from the overburden into the
mine block. It is projected that pumpage from the CSU
at approximately 4 mgd will lower the water table by
LEGGETTE, BRASHEARS & GRAHAM. INC.
-25-
about 5 feet at a distance of 500 feet from the eastern
boundary of Mine Block 20. Effects on the perched zone
will be insignificant at this distance due to the
impermeable nature of the Farmers Clay.
The canal system will mitigate pumping impacts on
localized water levels by seepage of water from the
canals into the Post-Croatan aquifer and CSU.
Historical records have shown that the mined-out
areas and precipitation have much greater control on the
water-table elevation than does the pumping from the CSU.
In fact, water-table elevations increased during the
testing of the CSU dewatering system. It is projected
that the water-table elevations in the area of the mine
blocks will continue to rise until the water levels in
Mine Block 16 and Mine Block 17 reach approximately 10
feet (msl).
CSU pumpage from wells located on the mine bench
will have little effect on the Post-Croatan aquifer or
CSU outside of the mine block. The pumpage from the
wellpoint system has a localized effect that does not
extend more than 600 to 800 feet outward from the
wellpoints.
It is anticipated that the effects on the water
table due to CSU pumping and overburden removal will
lower the water-table elevations a few feet over the
majority of the "wet area". The greatest effects will
be at the pumping wells and adjacent to the east boundary
of the mine block. The perched zone will not be
affected. The effects on water levels will last
approximately 12 months or until the area is mined. Once
the area has been mined, water levels will recover in the
Post-Croatan aquifer and in the CSU until they return to
their approximate pre-mined level.
LEGGETTE, BRASHEARS & GRAHAM, INC.
-26-
The water quality of the shallow-aquifer system as
determined from historical chloride analysis has not
deteriorated over the period-of-record.
LEGGETTE, BRASHEARS & GRAHAM, INC.
Henry B. Barker, PG
Senior Hydrogeologist
Reviewed by:
Frank H. Crum, PG
Senior Vice President
clg
LEGGETTE, BRASHEARS & GRAHAM, INC.
REFERENCES
LEGGETTE, BRASHEARS & GRAHAM, INC.
-27-
REFERENCES
Ardaman & Associates, Inc., 1989. Subsurface Exploration
and Laboratory Testing for Wetlands Investigation,
Texasgulf Phosphate Operations, Aurora, North
Carolina, Consultants Report.
DeGlee, G.J., 1951. Analysis and Elevation of Pumping
Test Data (1983).
Leggette, et al, 1988. Channel Sand Unit Pumping Test,
Consultants Report.
Walton, W.C., 1970. Groundwater Resource Evaluation,
McGraw - Hill Book Company, New York, New York. 664
P•
Gilmore, I.K., 1985. Preliminary Findings on the Channel
Structure in the Yorktown Clay, Texasgulf, Inc.
LEGGETTE, BRASHEARS & GRAHAM, INC.
TABLES
LEGGETTE, BRASHEARS & GRAHAM, INC.
TEXASGULF, INC., LEE CREEK MINE
CHANNEL SAND UNIT TEST
TABLE 1. CSU HYDRAULIC PROPERTIES AS DETERMINED
FROM CSU 54-DAY PUMPING TEST, JULY 1987
A. Time-Drawdown Analysis
TRANSMISSIVITY PERMEABILITY LEAKANCE
WELL NO. (GPD/FT) (GPD/FT2) STORAGE (GPD/ FT3) r /B METHOD
CTW-1 13,416 447 - - - 1
CTW-2 10,479 349 - - - 1
A-25 11,255 375 3.6x105 5.2x10 0.03 2
B-25 9,269 309 2.5x104 2
1.0x10-2 0.15 2
A-50 15,007 500 2.4x105 1.2x104 0.015 2
B-50 - - - - - -
23-85 10,166 338 3.8x104 5.7x103 0.15 2
CSU-1 17,316 962 3.5x10-4 2.1x10-3 0.20 2
41-85 19,454 721 7.8x104 1.8x103 0.30 2
CSU-2 26,263 238 8.6x104 2.7x103 0.30 2
CHU-1 28,650* 1433* - - 0.15 2
CSU-3 21,323 888 4.0x10-3 - - 3
CSU-4 20,332 1123 4.4x104 2.1x103 0.15 2
SB-1 21,016 1501* 3.5x104 2.1x10-3 0.15 2
CSU-5 19,453 846 4.0x10_4 1.7x103 0.30 2
CSU-6 49,120* - 2.16x103 1.1x10-3* 0.29 2
Averag e 17,386 591 7.2x10 2.9x10 - -

B. Distance-Drawdown Analysis
WELLS PARALLEL
TO CSU AXIS 13,690 563 - 2.2x103 - 4
WELLS PERPENDICULAR
TO CSU AXIS 15,607 679 - 1.2x103 - 4
Averag e 14.649 621 - 1.7x10 - 4

C. Time-Recovery Analy sis
CTW-1 11,169 372 - - - 3
CTW-2 9,680 323 - - - 3
CSU-1 26,400 880 2.6x104 - - 3
CSU-3 58,548* - 5.6x10'* - 3
CSU-4 15,783 1052 5.8x10-4 - - 3
CSU-5 24,200 1238 2.0x10-4 - - 3
CSU-6 62,843* - 6.4x104 - - 3
Averag e 17.446 773 3.5x10
D. Grand Averages From All Three Data Sources
16,494 662 5. 4x10-4 2.3x10_3
* Not used in average
- Parameter cannot be calculated in this method
1 Hantush Inflection Point Method
2 Walton Non-Steady State Leaky Artesian Method
3 Jacob Non-Steady State Confined Artesian Method
4 Hantush-Jacob Steady State Leaky Artesian Method
LEGGETTE, BRASHEARS & GRAHAM, INC.
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ATIONS
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LECCEM BRASHEi1R5 &
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JULY 8,1987
REVISED PREPARED BY:
DATE: FIGURE 6
PCS Pumping and Wetlands Report
Subject: PCS Pumping and Wetlands Report
From: [e-mail]
Date: Mon, 1 Dec 2008 11:22:48 -0500
To: [e-mail]
CC: [e-mail]
John:
In our meeting last Tuesday you requested a copy of the Leggette, Brashears
and Graham well pumping /wetland response report done in 1990 for the
previous EIS. I don't have an electronic copy, so I have scanned the text,
tables, and Figures 1-5 for you as an attachment to this e-mail. The
report talks about the perched zone (what is monitored for wetland
delineations) and the water table (separate and underneath the perched
zone). There is a good reason for me scanning the report upside down, but
you can rotate it.
Jeff
(See attached file: PCS Pumping - Wetland Report.pdf)
Jeff Furness
Senior Scientist
PCS Phosphate Co., Inc.
1530 NC Hwy 306 S
Aurora, NC 27806
Ph: [phone]
Fax: [phone]
PCS Pumping - Wetland Report.pdf Content-Type: application/pdf
Content-Encoding: base64
1 of 1 12/1/2008 11:28 AM