appendix d hydrology and...

Appendix D

Hydrology and Hydraulics

TECHNICAL MEMORANDUM

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1.0 INTRODUCTION Rare Element Resources (RER) is proposing a new open-pit mine for rare earth materials north of

Sundance, Wyoming referred to as the Bear Lodge Project, Bull Hill Mine. This memorandum describes

pre-feasibility level hydrology and hydraulics calculations for the site. The calculations were performed in

order to develop the framework for an initial stormwater management plan for the site, encompassing

possible stormwater diversions, runoff collection channels, haul road culverts, and sedimentation ponds.

2.0 METHODOLOGY

2.1 Hydrology Calculations Peak stormwater flow rates contributing to, or otherwise impacting the proposed facilities at the Bear

Lodge Project were estimated for the 100-year frequency, 6-hour duration storm event in accordance with

the Wyoming Department of Environmental Quality, Land Quality Division’s Guidelines (WDEQ). Using

the site topography provided by RER, basins were delineated for the Mineable Pit, Waste Rock Facility

(WRF), Haul Roads, and Plant Site (see Figure 1). The time of concentration for each basin was then

estimated using TR-55 methodology (NRCS, 1986). Curve numbers for the site were assigned using TR-

55 methodology (NRCS, 1986) in conjunction with soil survey information (NRCS, 2011). The 100-year

frequency, 6-hour duration, and 10-year frequency, 24-hour duration storm depths were estimated for the

site from the NOAA Atlas 2 (NOAA, 1973). Hydrologic modeling was then performed using the Hydrologic

Engineering Center’s Hydrologic Modeling System (HEC-HMS) (USACE 2010) to calculate runoff

volumes and peak flow rates.

2.2 Preliminary Sediment Pond Sizing In accordance with the Wyoming Department of Environmental Quality Water Quality Rules and

Regulations, Chapter 11, Section 31, the sediment ponds are sized to accommodate runoff from the 10-

year frequency, 24-hour duration event, which was modeled using HEC-HMS (Wyoming DEQ 2012).

Additionally, the ponds are sized to accommodate the expected sediment. In accordance with Michigan

Department of Environmental Quality guidelines, the sediment pond are sized, at a minimum, to contain

Date: February 13, 2014 Document No.: 11382323

To: Paul Bergstrom Company: Rare Element Resources

From: Micah Richey Email: [email protected]

cc: Tammy Rauen and Roman Popielak

RE: BEAR LODGE PROJECT, BULL HILL MINE – PRE-FEASIBILITY HYDROLOGY AND HYDRAULICS, REVISION E

Paul Bergstrom February 13, 2014 Rare Element Resources 2 11382323

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the volume of sediment equal to one inch of runoff from the entire catchment area, or 3,630 ft3/acre of

sediment (Michigan DEQ 2012).

In addition to storage for environmental flows from the pit and Basin Pt-N, the Pit Pond is also sized to

accommodate pit dewatering flows of 500 gallons per minute (gpm). The pond water and sediment

capacity is estimated using an assumed retention time (2 days) and settling velocity parameters based on

particle size.

2.3 Channel and Culvert Hydraulics Channel sizing calculations were performed with an open channel flow spreadsheet using Manning’s

equation. Riprap sizing was performed using U.S. Army Corps of Engineers methodology (USACE,

1994). Culvert crossings were modeled using HY8 culvert analysis software (FHWA 2011).

3.0 ASSUMPTIONS Runoff from the top of the WRF travels down the 1-percent slope to the north and south

then cascades perpendicular to the slopes, and is collected in a perimeter channel at the toe of the facility

Haul Road culvert crossings were located based on the proposed road alignments and topography supplied by RER

All calculations assume the following facility conditions:

Full build out of the Pit and WRF

The WRF is in a closed condition with 50-percent of the area reclaimed

The Low Grade Ore (LGO) stockpile has been processed and either been sent to the Upton facility or added to the footprint of the WRF

All runoff from the plant site is collected for discharge to a sedimentation pond

Time of concentration for both the Plant Site and the Mineable Pit are assumed to be 10 minutes

Channel lining criteria:

Design Flow Velocity (ft/s)

Channel Lining Material

<5 Grass 5 – 15 Riprap >15 Concrete, Articulated Concrete Block

Curve Numbers Used in hydrology calculations (NRCS,1986, Web Soil Survey):

Description of Soil & Land Cover

Woods-Grass Combination, HSG B, Fair Cover

Newly Graded Areas, HSG B

SCS Curve Number 65 86 Applicable Site Areas Undisturbed or Reclaimed

areas Disturbed Areas, Pit, Unreclaimed WRF, and Plant pad



Storm Depths (NOAA, 1973):

Storm Event 2-year 24-hour 10-year 24-hour 100-year 6-hour Storm Depth (in) 1.4 3.0 3.24 Applications Tc

Calculations Sedimentation Pond Volumes

Conveyance Channel, Riprap, and Culvert Sizing

Storm event temporal distribution – Dimensionless design mass curve (Tyrell & Hasfurther 1983)

Type II storm distribution

Manning’s n Coefficients:

Description

Manning’s n

Stability Capacity

Grass 0.030 0.035 Riprap 0.030 0.035 Mountain Stream 0.030 0.050 Corrugated Metal Pipe (CMP) 0.024 0.024

Haul Road Culverts:

Culverts are assumed to be corrugated steel with Manning’s n = 0.024

Length, available headwater depth, headwall configuration, downstream channel geometry, and slope are assumed or estimated from available topography

Channel Assumptions:

Slopes for flow routing and channel sizing calculations are the average slope across the entire reach

3H:1V side slopes

Minimum freeboard is 1 ft

4.0 CALCULATIONS Basin area-weighted curve number calculations are presented in Table 1. Time of concentration

calculations are presented as Table 2. The HEC-HMS model parameters are included as Attachment A

and calculated 100-year frequency, 6-hour duration and 10-year frequency, 24-hour duration peak flows

are included as Tables 3 and 3a respectively. Preliminary channel sizing calculations are presented in

Table 4. Preliminary riprap sizing calculations are presented in Tables 5 and 5a. HY-8 Culvert sizing

model output is included as Attachment B. Pit dewatering pond sizing calculations are included as

Attachment C.

5.0 CONCLUSIONS AND DISCUSSION Channel dimensions and revetment have been designed based on available topography and preliminary

facility designs. Dimensions and revetment requirements may change as the designs become more

detailed.



5.1 Proposed Stormwater Management Arrangement A berm around the upgradient side of the Mineable Pit highwall (PIT DIV N. and PIT DIV S.) prevents

surface water flows from running into the Mineable Reserve pit during the design storm event and diverts

the stormwater north and east into the existing drainages. Perimeter channels (as assumed) carry

stormwater flows along the north and west side of the WRF to a proposed sediment trapping pond on the

north side of the WRF (Pond 1 on Figure 1). Perimeter channel (as assumed) carry stormwater flows

along the north and east side of the WRF to a proposed sediment trapping pond on the northeast corner

of the WRF (Pond 2 on Figure 1). Perimeter channels (as assumed) carry stormwater flows along the

south side of the WRF to a proposed sediment trapping pond on the southeast corner of the WRF (Pond

3 on Figure 1). Parallel diversion channels along the south and west sides of the WRF will divert the

undisturbed upper reaches of Beaver Creek along the toe of the WRF and terminate into an upper

tributary of Beaver Creek. Perimeter channels along the north and south sides of the Plant Site Pad

(labeled PD-N and PD-S, respectively) convey flow to a sediment trapping pond on the east side of the

Plant Site Pad. The following table provides a summary of the proposed diversion channels:

Reach ID

100-yr/6-hr Peak Flow (cfs)

Length (ft)

Slope (ft/ft)

Side Slope (_H:1V) Bottom

Width (ft)

Depth (ft)

Freeboard (ft) Left Right

WRF 1 299.8 4110 0.030 3.0 3.0 20 2.5 1.0 WRF 2a 417.1 2400 0.030 3.0 3.0 20 3.0 1.2 WRF 2b 417.1 3580 0.030 3.0 3.0 20 3.0 1.2 WRF 3 556.8 7400 0.030 3.0 3.0 20 3.5 1.4 WRF DIV W 36.6 2505 0.080 3.0 3.0 10 2.0 1.5 PIT DIV S 48.5 2745 0.091 3.0 20.0 0 2.0 1.2 PIT DIV N1 65.1 3375 0.108 3.0 20.0 0 2.0 1.2 PIT DIV N2 101.2 1180 0.055 3.0 20.0 0 2.5 1.4 BC DIV U 280.7 2025 0.010 3.0 3.0 15 3.5 1.3 BC DIV L 370.7 1310 0.010 3.0 3.0 15 3.5 1.0 PD-N 157.5 1660 0.030 3.0 3.0 10 2.5 1.1 PD-S 70.4 410 0.073 3.0 3.0 10 2.0 1.3

5.2 Preliminary Sedimentation Pond Sizing The required volumes for each of the sediment trapping ponds are presented in the table below. The

volumes are representative of storage to accommodate runoff from the 10-year 24-hour event and

sediment storage. The Pit Pond also includes storage for water and sediment as a result of 500 gpm pit

dewatering (calculations presented in Appendix C). The ponds and any associated embankments will be

protected by outlet works and overflow spillways to be provided as part of detailed designs. The overflow

spillways will likely be designed to flow over the face of the embankment in a controlled manner in a



reinforced section. The ponds will require periodic maintenance and cleanout to ensure proper

functioning. The required freeboard storage of one foot is not included in these numbers.

Sediment Pond

Catchment Area (ac)

10-Year Event Volume (ac-ft)1

Sediment Storage Volume (ac-ft)2

Total Pond Volume (ac-ft)3

Waste Rock Facility Pond 1 104.5 14.5 8.7 23.2 Pond 2 143.8 19.9 12.0 31.9 Pond 3 211.7 29.3 17.6 46.9 Pit Pond Environmental Flows 249.1 32.4 20.8 65 Pit Dewatering - 4.4 7.4 PUG Plant PUG Plant Pond 45.1 6.3 3.8 10.1

Notes: 1. In accordance with the Wyoming Department of Environmental Quality Water Quality Rules and Regulations, Chapter 11,

Section 31, the sediment ponds are sized to accommodate the 10-year 24-hour runoff event. The design storm event was modeled using the Hydrologic Engineering Center's HEC-HMS program. Additionally, the ponds must be sized to accommodate the expected sediment storage.

2. The annual volume of sediment generated was assumed to be equal to one inch of runoff from the entire catchment area. This corresponds to 3,630 ft³/acre.

3. Total pond volume represents a neatline volume and does not include the required freeboard.

5.3 Haul Road Culvert Sizing Estimated culvert sizes are summarized in the table below.

Culvert Designation (See Figure 1)

Design Flow (cfs)

Culvert Size (in.)

Length (ft)

No. of Barrels

D1 70.4 36 450 2 D2 168.9 42 450 2



6.0 REFERENCES Association of State Dam Safety Officials (ASDSO) (2000): n. pag. Online. Internet. 20 January 2012.

Available: www.damsafety.org

HEC-HMS Hydrologic Modeling System [computer software] August 2010 US Army Corps of Engineers Version 3.5

Natural Resource Conservation Service (NRCS). 1986. Urban hydrology for small watersheds, 2nd edition (USSCS Technical Release Number 55). Washington D.C.: United States Department of Agriculture.

Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed January 20, 2012.

Tyrell, Patrick T. and Hasfurther, Victor R. Design Rainfall Distributions for the State of Wyoming. Department of Civil Engineering, College of Engineering, University of Wyoming. August 1983.

U.S. Army Corps of Engineers (USACE). 1994. Hydraulic Design of Flood Control Channels. Engineer Manual 1110-2-1601. Department of the Army. Washington D.C.: United States Government Printing Office.

U.S. Federal Highway Administration (FHWA). 2011. HY8 – Culverts Version 8.7.2 FHWA Culvert Analysis. Washington, DC: FHA Office of Technology Applications.

U.S. National Oceanic and Atmospheric Administration (NOAA). 1973. Precipitation Frequency Atlas of the Western US, Atlas No. 2, volume II – Wyoming. Silver Spring MD: US Department of Commerce.

Wyoming Department of Environmental Quality, Land Quality Division (WDEQ): Chapter 11, Section 31. Available: www.deq.state.wy.us/lqd/guidlines.asp.

TABLES

TABLE 1SUBBASIN SUMMARY TABLE

Date: 2/13/14Project Number: By: MBR

Chkd: SRDesign Storm 100 -Year Reccurence Interval Apprvd: REK

2-Year, 24-Hour Depth

(inches)

100-Year , 24-Hour Depth

(inches)Storm

Distribution1.4 3.2 II

CN = 65 CN = 86

Subbasin IDSubbasin Area

(ft2)

Subbasin Area

(acres)

Subbasin Area

(sq mile)

Woods-Grass Combo HSG B

Fair Cover(acres)

Newly Graded Areas HSG B

(acres)

Composite SCS Curve

No.

S = 1000 - 10CN

Unit Runoff Q

(in)

Runoff Volume (ac-ft)

Runoff Volume

(ft3)Pt S 2,560,076 58.77 0.0918 58.77 CN = 65 5.38 0.62 3.04 132,252Pt E 1,388,135 31.87 0.0498 31.87 CN = 65 5.38 0.62 1.65 71,710Pt NE 1,911,922 43.89 0.0686 43.89 CN = 65 5.38 0.62 2.27 98,769Pt N 961,099 22.06 0.0345 22.06 CN = 65 5.38 0.62 1.14 49,650WRF 1 4,551,559 104.49 0.1633 104.49 CN = 86 1.63 1.87 16.28 709,258WRF 2 6,262,079 143.76 0.2246 143.76 CN = 86 1.63 1.87 22.40 975,805WRF 3 9,221,573 211.70 0.3308 211.70 CN = 86 1.63 1.87 32.99 1,436,976BC 1 13,822,026 317.31 0.4958 317.31 CN = 65 5.38 0.62 16.39 714,036BC 2 6,455,220 148.19 0.2315 148.19 CN = 65 5.38 0.62 7.66 333,472Pd N 7,416,545 170.26 0.2660 165.86 4.40 CN = 66 5.15 0.66 9.41 409,955Pd S 3,653,339 83.87 0.1310 83.87 CN = 65 5.38 0.62 4.33 188,729HR 1 3,870,628 88.86 0.1388 88.86 CN = 65 5.38 0.62 4.59 199,954HR 2 2,328,253 53.45 0.0835 53.45 CN = 65 5.38 0.62 2.76 120,276WT 1 3,434,479 78.84 0.1232 78.84 CN = 65 5.38 0.62 4.07 177,423PLNT 1,964,918 45.11 0.0705 45.11 CN = 86 1.63 1.87 7.03 306,188Pit I 9,889,183 227.02 0.3547 227.02 CN = 86 1.63 1.87 35.38 1,541,008

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RARE ELEMENT RESOURCESBEAR LODGE MINE PRE-FEASIBILITY STUDY

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TABLE 2BASIN TIME OF CONCENTRATION CALCULATIONS

Date: 2/13/14By: MBR

Project Number: Chkd: SRApprvd: REK

Subbasin ID

Subbasin Area

(sq mile)Composite

Curve Number

Total Lag

(0.6*Tc) (min)

Total Travel Time(min)

Type of Flow

Length(ft)

Slope (ft/ft)

Typical Hydraulic Radius

(Channel Only)(ft)

Travel Time(min)

Type of Flow

Length(ft)

Slope (ft/ft)


(Channel Only)(ft)

Travel Time(min)

Pt S 0.0918 65 6.9 11.4 Sheet 80 0.188 H Range 4.4 Shallow 300 0.220 U Unpaved 0.7Pt E 0.0498 65 9.1 15.2 Sheet 100 0.240 H Range 4.8 Shallow 1150 0.184 U Unpaved 2.8Pt NE 0.0686 65 7.7 12.8 Sheet 100 0.200 H Range 5.2 Shallow 825 0.148 U Unpaved 2.2Pt N 0.0345 65 5.8 9.7 Sheet 100 0.170 H Range 5.5 Shallow 265 0.238 U Unpaved 0.6WRF 1 0.1633 86 8.5 14.1 Sheet 100 0.010 A Smooth 2.4 Shallow 610 0.010 U Unpaved 6.3WRF 2 0.2246 86 8.0 13.4 Sheet 100 0.010 A Smooth 2.4 Shallow 400 0.010 U Unpaved 4.1WRF 3 0.3308 86 11.8 19.7 Sheet 100 0.010 A Smooth 2.4 Shallow 610 0.010 U Unpaved 6.3BC 1 0.4958 65 20.1 33.6 Sheet 100 0.130 H Range 6.2 Shallow 1095 0.238 U Unpaved 2.3BC 2 0.2315 65 14.9 24.8 Sheet 100 0.180 H Range 5.4 Shallow 1145 0.195 U Unpaved 2.7Pd N 0.2660 66 9.8 16.4 Sheet 100 0.097 H Range 6.9 Shallow 1270.0 0.122 U Unpaved 3.8Pd S 0.1310 65 8.2 13.7 Sheet 100 0.137 H Range 6.0 Shallow 1805.0 0.137 U Unpaved 5.0HR 1 0.1388 65 13.5 22.5 Sheet 100 0.160 H Range 5.7 Shallow 680.0 0.262 U Unpaved 1.4HR 2 0.0835 65 7.8 13.0 Sheet 100 0.160 H Range 5.7 Shallow 670.0 0.221 U Unpaved 1.5WT 1 0.1232 65 6.8 11.3 Sheet 100 0.150 H Range 5.8 Shallow 425.0 0.278 U Unpaved 0.8

Notes:(1) Refer to Attachment A for Roughness Condition descriptions and Tc Coeffiecients.(2) PLNT and Pit I Subbasins times of concentration assumed to be 10 min

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Roughness Condition(1)

Flow Segment 1 Flow Segment 2

Roughness Condition(1)

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TABLE 2BASIN TIME OF CONCENTRATION CALCULATIONS

Project Number:

Subbasin ID

Subbasin Area

(sq mile)Composite

Curve NumberPt S 0.0918 65Pt E 0.0498 65Pt NE 0.0686 65Pt N 0.0345 65WRF 1 0.1633 86WRF 2 0.2246 86WRF 3 0.3308 86BC 1 0.4958 65BC 2 0.2315 65Pd N 0.2660 66Pd S 0.1310 65HR 1 0.1388 65HR 2 0.0835 65WT 1 0.1232 65

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RARE ELEMENT RESOURCESBEAR LODGE MINE PRE-FEASIBILITY ST


Chkd: SRApprvd: REK

Type of Flow

Length(ft)

Slope (ft/ft)


(Channel Only)(ft)

Travel Time(min)

Type of Flow

Length(ft)

Slope (ft/ft)


(Channel Only)(ft)

Travel Time(min)

Channel 2430 0.095 R Riprap 0.34 6.3Channel 1260 0.061 Z Mtn. Stream 0.23 7.6Channel 1610 0.062 R Riprap 0.32 5.4Channel 1320 0.133 E Earth-lined 0.15 3.6Shallow 190 0.279 U Unpaved 0.4 Channel 4000 0.101 R Riprap 0.96 5.1Shallow 1300 0.277 U Unpaved 2.6 Channel 3300 0.064 R Riprap 1.30 4.3Shallow 210 0.286 U Unpaved 0.4 Channel 7350 0.054 R Riprap 1.27 10.6Channel 4900 0.060 Z Mtn. Stream 0.50 17.8 Channel 1810 0.010 R Riprap 0.97 7.3Channel 3260 0.069 Z Mtn. Stream 0.42 12.4 Channel 1035 0.010 R Riprap 0.92 4.3Channel 1460 0.042 Z Mtn. Stream 0.66 2.6 Channel 1075 0.031 R Riprap 0.69 3.1Channel 1300 0.077 Z Mtn. Stream 0.36 2.6Channel 1950 0.092 Z Mtn. Stream 0.41 3.3 Channel 1880 0.064 Z Mtn. Stream 0.20 12.2Channel 1800 0.082 Z Mtn. Stream 0.21 5.0 Channel 260 0.059 R Riprap 0.32 0.9Channel 1100 0.159 Z Mtn. Stream 0.35 1.6 Channel 1250 0.089 R Riprap 0.38 3.1

Notes:(1) Refer to Attachment A for Roughness Condition descriptions and Tc Coeffiecients.(2) PLNT, Pit I, and Pit II Subbasins times of concentration assumed to be 10 min

Flow Segment 3 Flow Segment 4

Roughness Condition(1) Roughness Condition(1)


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TABLE 3FLOW RESULTS FROM HEC-HMS



HEC-HMS Basin Model: Bear Lodge Rev EHEC-HMS Met. Model: 100-year 6-hour

HEC-HMS Control Specs: 36-hour 5-minHEC-HMS filepath: J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\H&H calculations\HEC-HMS\BearLodge_Pre_Feas_RevE

Drainage Peak Total Hydrologic Area Discharge Time of VolumeElement (sq mile) (cfs) Peak (ac-ft)BC-1 0.496 184.7 02Jun2525, 01:00 16.4Pt-S 0.092 48.5 02Jun2525, 01:00 3R_Pt-E 0.092 47.8 02Jun2525, 01:00 3Pt NE 0.069 36.6 02Jun2525, 01:00 2.3Pt E 0.050 27 02Jun2525, 01:00 1.6Junction-Pt 0.210 111.4 02Jun2525, 01:00 6.9R_BC-1 0.210 96.4 02Jun2525, 01:05 6.9J_BC-1 0.706 280.7 02Jun2525, 01:05 23.3R_BC-2 0.706 280.3 02Jun2525, 01:05 23.3BC-2 0.232 108.4 02Jun2525, 01:00 7.7J_BC-2 0.938 370.7 02Jun2525, 01:00 31Sink-BC 0.938 370.7 02Jun2525, 01:00 31Pit I 0.355 705 02Jun2525, 00:55 35.4Pt N 0.035 19.1 02Jun2525, 00:55 1.1Sink-Pit 0.389 724.1 02Jun2525, 00:55 36.5Pd-N 0.266 157.5 02Jun2525, 01:00 9.4Pd-S 0.131 70.4 02Jun2525, 01:00 4.3Sink-1 0.397 227.9 02Jun2525, 01:00 13.7WT 1 0.123 65.1 02Jun2525, 01:00 4.1R_WT 0.123 64.8 02Jun2525, 01:00 4.1HR 2 0.084 44.7 02Jun2525, 01:00 2.8R_HR2 0.207 101.2 02Jun2525, 01:00 6.8HR 1 0.139 67.8 02Jun2525, 01:00 4.6Sink-4 0.346 168.9 02Jun2525, 01:00 11.4WRF 1 0.163 299.8 02Jun2525, 00:55 16.3Pond 1 0.163 299.8 02Jun2525, 00:55 16.3WRF 2 0.225 417.1 02Jun2525, 00:55 22.4Pond 2 0.225 417.1 02Jun2525, 00:55 22.4PLNT 0.071 140.1 02Jun2525, 00:55 7Sink-6 0.071 140.1 02Jun2525, 00:55 7WRF 3 0.331 556.8 02Jun2525, 01:00 33Pond 3 0.331 556.8 02Jun2525, 01:00 33


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TABLE 3A10-year 24-hour FLOW RESULTS FROM HEC-HMS



HEC-HMS Basin Model: Bear Lodge Rev DHEC-HMS Met. Model: 10-year 24-hour

HEC-HMS Control Specs: 36-hour 5-minHEC-HMS filepath: J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\H&H calculations\HEC-HMS\BearLodge_Pre_Feas_RevD

Drainage Peak Total Hydrologic Area Discharge Time of VolumeElement (sq mile) (cfs) Peak (ac-ft)BC-1 0.496 142.3 02Jun2525, 01:05 13.4Pt-S 0.092 38.7 02Jun2525, 01:00 2.5R_Pt-E 0.092 36.8 02Jun2525, 01:00 2.5Pt NE 0.069 29.1 02Jun2525, 01:00 1.9Pt E 0.050 21.3 02Jun2525, 01:00 1.3Junction-Pt 0.210 87.2 02Jun2525, 01:00 5.7R_BC-1 0.210 77.8 02Jun2525, 01:05 5.6J_BC-1 0.706 220 02Jun2525, 01:05 19R_BC-2 0.706 218.1 02Jun2525, 01:05 19BC-2 0.232 83.1 02Jun2525, 01:00 6.2J_BC-2 0.938 289.7 02Jun2525, 01:05 25.3Sink-BC 0.938 289.7 02Jun2525, 01:05 25.3Pit I 0.355 628.2 02Jun2525, 00:55 31.4Pt N 0.035 14.6 02Jun2525, 00:55 0.9Sink-Pit 0.389 642.8 02Jun2525, 00:55 32.4Pd-N 0.266 125.8 02Jun2525, 01:00 7.7Pd-S 0.131 55.8 02Jun2525, 01:00 3.5Sink-1 0.397 181.6 02Jun2525, 01:00 11.3WT 1 0.123 52 02Jun2525, 01:00 3.3R_WT 0.123 51.2 02Jun2525, 01:00 3.3HR 2 0.084 35.5 02Jun2525, 01:00 2.3R_HR2 0.207 76 02Jun2525, 01:00 5.5HR 1 0.139 52.3 02Jun2525, 01:00 3.7Sink-4 0.346 128.3 02Jun2525, 01:00 9.3WRF 1 0.163 266.7 02Jun2525, 00:55 14.5Pond 1 0.163 266.7 02Jun2525, 00:55 14.5WRF 2 0.225 371.1 02Jun2525, 00:55 19.9Pond 2 0.225 371.1 02Jun2525, 00:55 19.9PLNT 0.071 124.9 02Jun2525, 00:55 6.3Sink-6 0.071 124.9 02Jun2525, 00:55 6.3WRF 3 0.331 497.5 02Jun2525, 01:00 29.3Pond 3 0.331 497.5 02Jun2525, 01:00 29.3


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Table 4Channel Hydraulic Calculations

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RARE ELEMENT RESOURCES Date: 12/6/13BEAR LODGE MINE PRE-FEASIBILITY STUDY By: AMSPROJECT NO.: 113-82323 Chkd: MBR

Apprvd: RP

Reach Designation

Q100from

HEC-HMS(cfs)

HEC HMSElement ID

for Q

Approximate Channel Length

(ft)

Bed Slope(ft/ft)

Left Side

Slope(H:1V)

Right Side

Slope(H:1V)

Bottom Width

(ft)

Minimum Channel Depth

(ft)

Mannings 'n' for Capacity

(Depth Calculation)

Mannings 'n' for Stability

(Velocity Calculation)

Maximum Velocity(ft/sec)

Maximum Normal Flow

Depth(ft)

Froude Number

Normal Depth Shear

Stress(lb/ft2)

Stream Power(W/m2)

Top Width of Flow(ft)

Top Width of Channel

(ft)WRF 1 299.8 WRF 1 4110 0.030 3.0 3.0 20 2.5 R Riprap 0.035 0.030 9.3 1.46 1.54 2.74 370.19 28.8 35.0 1.0WRF 2a 417.1 WRF 2 2400 0.030 3.0 3.0 20 3.0 R Riprap 0.035 0.030 10.4 1.76 1.58 3.30 497.32 30.6 38.0 1.2WRF 2b 417.1 WRF 2 3580 0.030 3.0 3.0 20 3.0 R Riprap 0.035 0.030 10.4 1.76 1.58 3.30 497.32 30.6 38.0 1.2WRF 3 556.8 WRF 3 7400 0.030 3.0 3.0 20 3.5 R Riprap 0.035 0.030 11.4 2.07 1.61 3.88 641.14 32.4 41.0 1.4WRF DIV W 36.6 Pt NE 2505 0.080 3.0 3.0 10 2.0 R Riprap 0.035 0.030 7.4 0.48 2.10 2.37 255.92 12.9 22.0 1.5PIT DIV S 48.5 Pt-S 2745 0.091 3.0 20.0 0 2.0 R Riprap 0.035 0.030 7.7 0.78 2.23 4.46 497.35 18.0 46.0 1.2PIT DIV N1 65.1 WT 1 3375 0.108 3.0 20.0 0 2.0 R Riprap 0.035 0.030 8.8 0.85 2.46 5.73 733.11 19.5 46.0 1.2PIT DIV N2 101.2 R_HR2 1180 0.055 3.0 20.0 0 2.5 R Riprap 0.035 0.030 7.7 1.14 1.84 3.91 433.51 26.1 57.5 1.4BC DIV U 280.7 J_BC-1 2025 0.010 3.0 3.0 15 3.5 R Riprap 0.035 0.030 6.6 2.20 0.93 1.37 131.15 28.2 36.0 1.3BC DIV L 370.7 J_BC-2 1310 0.010 3.0 3.0 15 3.5 R Riprap 0.035 0.030 7.2 2.55 0.95 1.59 165.28 30.3 36.0 1.0PD-N 157.5 PD-N 1660 0.030 3.0 3.0 10 2.5 R Riprap 0.035 0.030 8.6 1.43 1.50 2.68 335.0 18.6 25.0 1.1PD-S 70.4 PD-S 410 0.073 3.0 3.0 10 2.0 R Riprap 0.035 0.030 9.0 0.71 2.13 3.25 426.0 14.3 22.0 1.3

< 1/2 Vel. Head indicates that the remaining freeboard is less than 1/2 the velocity head (V2/2g)suggesting water may splash out.

Warning: VxD>9 indicates that the velocity times the depth is greater than 9 ft2/sec, which is undesirable and may be unUnstable V indicates that calculated velocity exceeds the recommended maximum for the lining material.Unstable T indicates that calculated shear stress exceeds the recommended maximum for the lining material.

Design Channel Lining

Channel Roughness Parameters

Available Freeboard(ft)

Hydraulic CalculationsChannel Design Geometry Channel Evaluations

Table 5aU.S. Corps of Engineers (mild) Method Riprap Size Calculation

J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\H&H calculations\Bear Lodge Riprap Rev D.xlsm


1/14/2014

Riprap Channel Evaluation Date: 12/6/13Bear Lodge Mine By: AMSPROJECT NO.: 113-82323 Chkd: MBR

Apprvd: RP

Reach Designation

Design Flow

Q (cfs)

Normal Flow Depth

d (ft)

Depth Averaged VelocityV (ft/s)

Velocity Distribution Coefficient

CV

Channel Side Slopes Correction

K1

Calculated Particle

Size D30 (ft)

Riprap Size

D50 (in)

Recommended Riprap D50

(inches)BC DIV U 280.7 2.02 6.60 1.00 0.97 0.20 3.2 6.0BC DIV L 370.7 2.35 7.17 1.00 0.97 0.24 3.8 6.0

USACE Paper EM 1110-2-1601, 6/30/94

Inputs below as determined in EM 1110-2-1601, 6/30/941.1 Sf: Minimum safety factor of 1.1 for moderate debris impact0.3 Cs: Value of 0.30 for angular rock165 γs: Density of solids (pcf)2.2 Cg: Gradation Coefficient (D85/D15)2.0 T: Riprap Thickness (x D50)

0.910 CT: Correction for thickness > 1.5 * D50

Note: A CV of 1.25 should be used downstream of concrete channels due to the difference in velocity profiles

Riprap D50 determined as recommended in EM 1110-2-1601, 6/30/94

USACE MethodRiprap Calculations for Mild Riprap (Bed Slopes <2%)

5.2

130

−

=gdK

VdCCCSDws

wTVsf γγ

γ

31

15

853050

=

DDDD

Table 5U.S. Corps of Engineers (Steep) Method Riprap Size Calculation

J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\H&H calculations\Bear Lodge Riprap Rev D.xlsm


1/14/2014

Riprap Channel Evaluation Date: 12/6/13Bear Lodge Mine By: AMSPROJECT NO.: 113-82323 Chkd: MBR

Apprvd: RP

Reach Designation

Design Flow Q

(cfs)

Normal Flow Depth

d(ft)

Unit Flow(ft2/sec)

Flow Concentration

Factor

Calculated Particle Size D30

(ft)

Riprap Size D50

(inches)

Recommended Riprap D50

(inches)WRF 1 299.8 1.34 12.48 1.25 0.55 8.5 9WRF 2a 417.1 1.62 16.79 1.25 0.67 10.4 12WRF 2b 417.1 1.62 16.79 1.25 0.67 10.4 12WRF 3 556.8 1.90 21.66 1.25 0.79 12.3 12WRF DIV W 36.6 0.44 3.24 1.25 0.38 6.0 9PIT DIV S 48.5 0.74 5.69 1.25 0.60 9.4 12PIT DIV N1 65.1 0.80 7.07 1.25 0.76 11.9 12PIT DIV N2 101.2 1.07 8.21 1.25 0.58 9.0 9PD-N 157.5 1.31 11.30 1.25 0.51 8.0 9PD-S 70.4 0.65 5.89 1.25 0.54 8.5 9* Reach HR-U is consumed by the Reserve Pit

USACE Paper EM 1110-2-1601, 6/30/94

Inputs below as determined in EM 1110-2-1601, 6/30/942.2 Cg: Gradation Coefficient (D85/D15)

Riprap D50 determined as recommended in EM 1110-2-1601, 6/30/94

1.25 Flow Concentration Factor (1.25 from USACE steep riprap method)

USACE MethodRiprap Calculations for Steep Riprap (Bed Slopes >2% but <20%)

31

32555.0

3095.1

g

qSD =

31

15

853050

=

DDDD

FIGURE

WRF 1

Pd N

Pt NE

PRE-FEASABILITYWATERSHED MANAGEMENT PLAN

RARE ELEMENT RESOURCESBEAR LODGE PROJECT, BULL HILL MINE

CROOK COUNTY, WYOMING

FIGURE 1

LEGEND

WRF S

NOTES

ATTACHMENT A HEC-HMS MODEL PARAMETERS

Attachment AHEC-HMS Screen Captures and Inputs

113-82323

HEC-HMS Basin Model Schematic (Mineable Scenario)

SubbasinArea(mi2) Subbasin

Initial Abstraction

(in)Curve

NumberImpervious

(%) SubbasinLag Time

(hr) %Time %RainfallBC-1 0.4958 BC-1 65 0 BC-1 0.336 0 0Pt-S 0.0918 Pt-S 65 0 Pt-S 0.114 10 10Pt NE 0.0686 Pt NE 65 0 Pt NE 0.128 20 23Pt E 0.0498 Pt E 65 0 Pt E 0.152 30 34BC-2 0.2315 BC-2 65 0 BC-2 0.248 40 45Pit I 0.3547 Pit I 86 0 Pit I 0.100 50 56Pt N 0.0345 Pt N 65 0 Pt N 0.097 60 67Pd-N 0.2660 Pd-N 66 0 Pd-N 0.164 70 77Pd-S 0.1310 Pd-S 65 0 Pd-S 0.137 80 86WT 1 0.1232 WT 1 65 0 WT 1 0.113 90 94HR 2 0.0835 HR 2 65 0 HR 2 0.130 100 100HR 1 0.1388 HR 1 65 0 HR 1 0.225WRF 1 0.1633 WRF 1 86 0 WRF 1 0.141WRF 2 0.2246 WRF 2 86 0 WRF 2 0.134PLNT 0.0705 PLNT 86 0 PLNT 0.100WRF 3 0.3308 WRF 3 86 0 WRF 3 0.197

ReachLength

(ft)Slope(ft/ft) Manning's n subreaches Shape

Diameter(ft)

Width(ft)

Side Slope(xH:1V)

R_Pt-E 1560 0.066 0.03 2 Trapezoid 10 12R_BC-1 1310 0.01 0.03 2 Trapezoid 10 3R_BC-2 555 0.054 0.03 2 Trapezoid 10 3R_WT 480 0.03 0.03 2 Trapezoid 10 5R_HR2 1785 0.08 0.03 2 Trapezoid 50 9

Sub Basin AreaLoss

SCS Curve NumberTransform

SCS Unit Hydrograph

RoutingKinematic Wave Channel

Dimensionless S-Graph


Page 1 of 1Golder Associates, Inc.

2/13/2014

ATTACHMENT B HY8 CULVERT SIZING OUTPUT

December 2013 Attachment B 113-82323 HY-8 Culvert Analysis

j:\11jobs\113-82323 bear lodge mine\surface water\h&h calculations\hy8\attachment b hy-8 rev d.docx

Culvert D1 Inputs



Culvert D1 Outputs



Culvert D2 Inputs



Culvert D2 Outputs

ATTACHMENT C PIT DEWATERING SEDIMENT POND SIZING

February 2014 1 113-82323

Sediment Pond Catchment Area (ac)

10-Year Event Volume (ac-ft) 1

Sediment Storage Volume (ac-ft) 2

Total Pond Volume (ac-ft) 3

Pond 1 104.5 14.5 8.7 23.2Pond 2 143.8 19.9 12.0 31.9Pond 3 211.7 29.3 17.6 46.9

Environmental Flows 249.1 32.4 20.8Pit Dewatering - 4.4 7.4

PUG Plant Pond 45.1 6.3 3.8 10.1Notes:

3. Total pond volume represents a neatline volume and does not include the required freeboard.

2. The annual volume of sediment generated was assumed to be equal to one inch of runoff from the entire catchment area. This corresponds to 3,630 ft3/acre.

Table C1: Sediment Pond Sizing Summary

Waste Rock Facility

Pit Pond

65.0

PUG Plant

1. In accordance with the Wyoming Department of Environmental Quality Water Quality Rules and Regulations, Chapter 11, Section 31, the sediment ponds are sized to accommodate the 10-year 24-hour runoff event. The design storm event was modeled using the Hydrologic Engineering Center's HEC-HMS program. Additionally, the ponds must be sized to accommodate the expected sediment


December 2013 Attachment CSettling Velocity Calculations

113-82323

J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\November 2013\Pit Dewatering Pond\SedBasin_1.xls

1. Calculation of the settling velocity u of a single particle: natural sediment or sphericalinput cel: yellowcalculation cel: blue

INPUT:Acceleration of gravity g = 9.81 m/s2 usually g = 9.81 m/s2

Density of particle ρPARTICLE = ρP = 1100 kg/m3

Diameter of particle d = 0.00025 meter (Be Aware: 1 mm = 0.001 m) Assume Fine sandDensity of fluid ρFLUID = ρF = 1000 kg/m3 usually water ρF = 1000 kg/m3

Viscosity of fluid ηFLUID = ηF = 0.001 Pa s usually water ηF = 0.001 Pa s

"Dimensionless particle diameter d*"= 2.484065317Natural particles (Song Zhiyao): Settling velocity u = 0.002304019 m/s Re = ρF*u*d/ηF = 5.76E-01

0.007559116 ft/sSpherical particles (Guo): Settling velocity u = 0.003026225 m/s Re = ρF*u*d/ηF = 7.57E-01

0.009928559 ft/s

VS = 0.01 ft/s Settling velocity for the design particle size chosenQ = 1.11 cfs

500 gpm Discharge rate measured in cubic feet per secondAS = 177 sq. ft. Minimum surface are for trapping soil particles of a certain size

Janwillem Rouweler; HAS University of Applied Sciences; N

mailto:[email protected]



December 2013 Attachment CPond Sizing Calculations

113-82323

J:\11JOBS\113-82323 Bear Lodge Mine\Surface Water\November 2013\Pit Dewatering Pond\SedBasin_1.xls

m3/day 2725.5gpd 720000gpm 500

Influent TSS mg/L 1500Effluent TSS mg/l 35

Mass of Sludge without Anaerobic Decomposition kg/yr 1,457,391 Ratio of Fixed Solids to VSS - 0.00Volatile Solids kg/yr - Fixed Solids kg/yr 1,457,391 Volatile Solids Reduction % 0%Sludge Accumulation years 1VSS decomposition years 1VSS @ yr 1 kg/yr - Total SS Mass @ yr 1 kg @ yr 1 1,457,391 Total Solid Mass @ yr 1 kg 1,457,391 Detention Time days 2

m3 5,451 gallons 1,440,000 ac-ft 4.4

Lagoon Depth m 1.00m2 5,451 ft2 58,653

Mass of Accumulated Sludge / Area kg/m2 267Density of Sludge kg/m3 1.06Average Compaction % 15%Sludge Bank Depth m 1.68

m 2.68ft 8.80

Length to width ratio 3.0ft 419.5m 127.9ft 139.8m 42.6

Laminar Velocity ft/s 0.0024Laminar Velocity Contingency - 0.50Adjusted Laminar Velocity ft/s 0.0036Settling Velocity ft/s 0.0076Settling Velocity - Adjusted Laminar Velocity ft/s 0.0039Water Storage ac-ft 4.4Sediment Storage ac-ft 7.4Total Required Storage ac-ft 11.8

Width

Sedimentation Basin

Influent Parameters

Flow

Volume

Total Lagoon Depth

Surface Area

Length

appendix d hydrology and...

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