minntac subwatershed impacts final...west branch - trib 1 47 0 047 0.05 0.00 0.00 0.05 west two...
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Liesch Associates, Inc. 13400 15th Avenue North Minneapolis, MN 55441 Phone: (763) 489-3100 Toll Free: (800) 338-7914 Fax: (763) 489-3101
M E M O R A N D U M
TO: Tom Moe; U. S. Steel Minntac
FROM: Michael Johnson, PE & Kristoffer Langlie, PE; Liesch Associates
DATE: July 3, 2012
RE: U. S. Steel Minntac Subwatershed and Stream Information
Liesch Associates has completed this technical memorandum for U. S. Steel to provide potential stream impact information as a result of the proposed U. S. Steel Minntac (Minntac) Mine Extension. The Minnesota Department of Natural Resources and U. S. Steel provided Liesch a list of streams/subwatersheds to evaluate within the confines of the Minntac mining operation. The areas evaluated were streams/subwatersheds that were either previously impacted by past mining, are slated to be impacted within the existing Permit-to-Mine (PTM) boundary via active mining, or have the potential to be impacted by the proposed mine extension. The streams/subwatersheds included:
McQuade/Kinney Creek – Tributary 1 (M1);
Kinross Creek – Tributary 1 (K1), Tributary 2 (K2) & Tributary 3 (K3);
West Branch of the West Two River – Tributary 1 (W1), Tributary 2 (W2) & Tributary 3 (W3);
East Branch of the West Two River (Mt. Iron) – Tributary 1 (MI1);
Parkville Creek – Tributary 1 (P1), Tributary 2 (P2), Tributary 3 (P3), & total Parkville Creek drainage area upstream of the study point (including the area drained by the mainstem (P4)).
East Two River – Tributary 1 (E1)
The southern boundary for the drainage area of each stream was determined to be the proposed mining extension limit. Each stream subwatershed was then delineated upstream of the southern boundary of the proposed extension based off pre-mining/USGS contours. Figure 1 presents the locations of the delineated subwatershed boundaries, along with the current extent of mining within the subwatershed boundaries where the mine face has not reached the current PTM, the existing PTM limits, and the proposed extension limits.
The stream contributing area and stream segment channel length were then determined and are summarized within Table 1 for four classifications:
pre-mining
already impacted by past mining (current extent of mining)
to be impacted by existing PTM
to be impacted by proposed extension of PTM
To establish Average Annual Runoff Flow Rates (AARFR), a Generalized Mean Annual Runoff (GMAR) value of 9.5 inches per year was selected for the study area based on data published in SIR
Page 2 July 3, 2012
2009-5250 - Techniques for Estimating the Magnitude and Frequency of Peak Flows on Small Streams in Minnesota Based on Data through Water Year 2005 (USGS, 2009). This value was then utilized with the contributing area and applied to the following calculation:
s
d
d
yr
in
ftGMARin
ac
sfacCntrbAreaCFSAARFR
60
min1
min1440
1
365
1
12
1)(5.9
1
560,43)()(
The results of the Average Annual Runoff Flow Rates are included with Table 1. The majority of the reduction in runoff flow rates have occurred as a result of past mining, and all of the runoff flow rates from the study areas were reduced by 0.25 CFS or less as a result of the proposed extension of the PTM.
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Table 1: Subwatershed and Stream InformationU. S. Steel - Minntac
Minntac West PitEvaluation of Past, Present and Proposed Impacts to Watersheds
Pre-mining(ac)
Already Impacted by Past Mining
(ac)
To be Impacted by Current PTM
(ac)
To be Impacted by Proposed
Extension(ac)
Pre-mining(ft)
Already Impacted by past mining
(ft)
To be Impacted by Current PTM
(ft)
To be Impacted by Proposed
Extension(ft)
Pre-mining(cfs)
Already Impacted by Past Mining
(cfs)
To be Impacted by Current PTM
(cfs)
To be Impacted by Proposed
Extension(cfs)
McQuade Ck Trib 1 2,657 2,513 62 82 17,983 17,983 01 01 2.91 2.75 0.07 0.09 (aka Kinney Creek)
Kinross Creek Trib 1 50 10 11 29 0.05 0.01 0.01 0.03Trib 2 220 99 29 92 0.24 0.11 0.03 0.10Trib 3 606 600 0 6 0.66 0.66 0.00 0.01
West Branch - Trib 1 47 0 0 47 0.05 0.00 0.00 0.05 West Two River Trib 2 638 490 139 9 0.70 0.54 0.15 0.01
Trib 3 293 58 235 0 0.32 0.06 0.26 0.00
East Branch - (Mt. Iron) Trib 1 3,032 3,032 0 0 3.32 3.32 0.00 0.00 West Two River (incl some East Pit)
1 The USACE has indicated that the MN DNR 24k Stream Segments shown in the M1 Subwatershed feeding Yates Lake may have been streams at one time, but would no longer be considered Jurisdictional under existing USACOE regulations.
Mi t E t Pit
Watershed Contributing Area Average Annual Runoff Flow RateStream segment channel length
N/A - USACOE determined no streams present within proposed progression area, wetland area only.
Minntac East PitEvaluation of Past, Present and Proposed Impacts to Watersheds
Pre-mining(ac)
Already Impacted by Past Mining
(ac)
To be Impacted by Proposed
Extension(ac)
Pre-mining(ft)
Already Impacted by Past Mining
(ft)
To be Impacted by Proposed
Extension(ft)
Pre-mining(cfs)
Already Impacted by Past Mining
(cfs)
To be Impacted by Proposed
Extension(cfs)
Parkville Creek Trib 1 460 360 100 4,706 4,7063 0 0.50 0.39 0.11
Trib 2 165 145 20 3,447 3,4473 0 0.18 0.16 0.02Trib 3 338 338 0 4,452 4,452 0 0.37 0.37 0.00Main 1,685 1,600 85 17,208 13,206 4,002 1.84 1.75 0.09
TOTAL Parkville Ck2 2,648 2,443 205 29,813 25,811 4,002 2.90 2.67 0.22
East Two River Trib 1 331 331 0 1,329 1,329 0 0.36 0.36 0.00
2 TOTAL Parkville Creek subwatershed represents information from Tributaries 1 (P1), 2 (P2), and 3 (P3), along with one other area (P4) shown on Figure 1 which represent the main reach of Parkville Creek.
3 The USACOE has indicated that the MN DNR 24k Stream Segments shown in the P1 & P2 Subwatersheds may have been streams at one time, but would no longer be considered Jurisdictional under existing USACOE regulations.
Watershed Contributing Area Stream segment channel length Average Annual Runoff Flow Rate
15
25
1530
1565
15
60
15
35
15
55
15
50
15
40
15
45
1520
15
70
1575
15
95
1590
1585
1580
1600
1515
15
10
15
05
15
00
14
95
1490
14851480
14751470
1610
16
05
14651
460
1455
1450
1445
1625
16
15
16
30
1620
1665
1440
1645
1435
1650
1655
1660
1430
16
75
1670
1680
16
40
1635
1685
1690
1425
1695
1700
1705
1710
1715
1720
1725
1730
1735
1740
1745
1420
1750
1760
1755
17
65
1770 1775
1405
14
15
14
10
1400
1790
1785
17
80
1820
1800
1795
1815
1805
1810
1395
18
30
1825
18351840
1845
1850
1855
18
15
1590
1575
1500
1820
1750
1505
1475
1535
1460
1745
1490
1670
1560
1485
1410
1710
1485
1525
1440
17
80
14
35
17
40
1500
1530
1455
1495
15
75
1520
14
15
1580
1515
17
80
1500
1730
1575
1645
1755
16
95
1415
1435
1670
1640
1575
1520
1515
1510
1785
1820
1510
1760
1455
1575
1540
1515
1450
1600
1815
1835
1480
1430
1605
1515
1535
1605
1430
1790
1625
1585
1550
1485
1805
1465
1820
1520
1760
1490
1435
1800
1460
1485
1750
15251530
1755
1730
14
95
18
20
1610
1550
1655
1735
1450
1620
1500
1790
14
65
1430
1590
1750
14
75
1420
1555
1500
14
25
1625
1480
17301800
1435
1705
14
85
1505
1660
1605
1665
1475
1530
1825
1755
1440
1765
1560
1495
14
30
1470
1540
1500
1770
1430
16
15
1595
1435
1545
1550
1840
1545
1470
1745
1580
1510
1540
1690
1530
14
20
1730
1600
1430
1490
1525
1505
1610
1530
1630
1760
1620
15
35
1710
1655
1400
1770
1410
1680
1610
1495
1445
1490
1740
1760
1505
17
15
1700
15
05
17
00
16
35
1410
14
80
1705
1695
1805
1630
1515
1765
1430
15
25
1505
14
70
1540
1665
1755
1440
1620
17
50
1635
1715
1475
1545
1705
1590
1535
14
30
1420
1490
1755
1425
1440 1480
15
20
1685
16
75
1440
1410
1540
1430
1730
1515
1635
1710
15
10
1575
15
75
1475
1505
1770
1565
1690
1445
1715
17
35
1570
1765
15
10
1485
14
70 1470
1780
14
80
1555
1685
14
90
1470
1710
1740
1515
1505
1530
1565
15
40
15
20
1425
1625
1490 1440
1450
1660
1430
1505
1580
1650
1685
1660
1440
1795
1765
15
40
1610
1625
1500
1420
15
50
1780
1415 1440
1580
1730
15
50
15
00
1625
17
65
1450
15
50
1525
1510
1765
16
50
1685
1420
1700
1405
1780
1555
1555
1730
1695
1590
1545
1525
1625
16
95
1795
1705
15
75
1490
14
90
17
25
1710
1530
14
30
1495
1450
1700
1620
1435
15
35
1630
15
35
1605
1515
1665
1695
1530
1755
1745
1745
15
75
1565
1490
17351515
1595
15
30
1735
1480
1565
1425
1585
15
55
1505
1485
1785
1710
1620
1680
15
10
18
25
1555
15
15
1540
1630
1480
17401750
14
30
1500
1535
1525
1445
1710
1520
1645
1695
1720
1700
1525
1435
1575
1495
15
00
1765
1500
1550
1620
1550
1450
15
75
1535
1810
1690
1825
1705
1535
1500
1470
1715
1560
1610
1435
15
80
1575
1550
1430
1580
1565
1655
1575
1775
1510
1590
16
75
1455
1760
1505
1460
1520
1550
14
60
14
75
1565
1685
14
30
1585
1520
1420
1775
1515
1500
14
80
1555
1530
1500
1805
1785
1700
1670
15
80
1675
1775
1700
1500
1515
1435
15
30
1550
1470
1460
1720
1495
1630
14
90
1515
1540
1620
1490
14
90
17251580
1690
1485
1665
1580
1720
1535
15
10
14
80
1430
1650
17
15
13
95
1680
1525
14
75
1715
1450
1480
1795
1730
1470
1720
1510
1625
1425
1490
1550
15
10
1500
1520
1430
1745
1725
1700
1400
1695
1760
1560
1430
1730
1570
1440
1705
1625
1540
1700
1565
1645
1515
1705
1755
1435
1605
1500
1700
1635
1510
1435
1635
1495
1470
1425
1445
1715
14
65
1465
15
05
1560
1525
1475
16
70
14
70
1460
1600
1495
17
10
1480
1655
1455
1485
16
70
17
75
1485
1685
1430
15
00
15
95
1515
1505
1660
1610
1460
1650
17
25
1545
1475
1435
1690
1625
1420
15
10
14
65
1620
1535
1755
1495
1460
1525
1735
1460
1550
1520
1540
1395
1535
1435
1605
1485
1515
1680
1420
14
95
1750
1535
1590
14
15
1425
1565
1670
1745
1630
1615
1465
1675
1765
1720
14
35
1530
1610
1540
1530
1460
1680
1520
17001770
15
10
1690
1545
1430
1560
1430
1495
1460
16
55
1425
14
65
1525
1555
1665
1715
1465
1550
1480
1410
1490
1495
1605
1515
1675
1750
15901750
1520
1680
15
20
15
10
15
10
1740
16
70
15
20
1480
1485
1470
15501530
1545
1590
1540
1530
15
35
1415
1490
141
5
1425
16
90
1480
1475
1690
15
40
1675
1580
1765
1545
1480
17
15
1480
1505
15
25
15
15
17
30
15
40
1695
1520
1590
1830
17
20
1505
1745
1655
1435
1570
1645
1425
1525
1585
1615
1565
1510
1500
1710
1505
1580
14
25
14
55
1725
1480
15
05
1665
1525
1495
1530
1505
1530
1465
14
75
1530
15
40
1695
1515
1605
1550
1650
1620
1475
1465
1595
1395
1400
1675
1455
1705
1435
1620
1670
1700
1485
1610
14
85
1420
1525
1575
15
70
1580
1485
1435
1495
1550
1420
1515
1500
15
65
1550
1700
1415
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www.liesch.com
Minneapolis ▪ Los Angeles ▪ Milwaukee ▪ Phoenix
Hydrogeologists ▪ Engineers ▪ E nv ironmen ta l Scientists Source: ESRI Basemap
Projection: NAD83 UTM Zone15N
U. S. Steel - Minntac
Pre-Mining Subwatershed DelineationFigure
1
Jul 12
w:\
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Fig
1 2
01
2-0
70
3.p
df
¹
0 0.5 10.25 Miles
M1
K1
K2
W2
P1
P2
P3
P4
K3
MI1
E1
Stream Length (ft)
Subwatershed Impact Areas
Already Impacted by Past Mining
To be Impacted by Current PTM
To be Impacted by Proposed Extension
W3
W1
17208
4452
3447
4706
15396
2587
xxxx
P4
Parkvill
e
Ea
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wo R
iverCre
ek
Ea
st B
ran
ch -
Wes
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Riv
er
Un
na
med
Wes
t B
ra
nch
-
Cre
ek
Kin
ross
McQ
ua
de
(Kin
ney
) C
reek
1329
MN DNR 24k Streams
Existing Permit to Mine Limits
Proposed Extension Limits
Current Extent of Mine
Subwatershed Boundaries