CCR Rule Design Criteria (a)(2) Periodic Hazard Potential Classification Assessment

Transcription

1 CCR Rule Design Criteria (a)(2) Periodic Hazard Potential Classification Assessment FGD Pond 5 Naughton Power Plant Kemmerer, Wyoming October 30, 2017 PREPARED FOR PacifiCorp 1407 West North Temple Salt Lake City, UT (801) Fax (801) PREPARED BY Tetra Tech 1551 Three Crowns Drive Suite 210 Casper, Wyoming

2 PROFESSIONAL ENGINEER CERTIFICATION I hereby certify, as a Professional Engineer in the State of Wyoming, that the information in this document was assembled under my direct supervisory control. This report is not intended or represented to be suitable for reuse by PacifiCorp or others without specific verification or adaptation by the Engineer. I hereby certify that this report has been prepared in accordance with 40 CFR (a)(2), and that a satisfactory demonstration of the requirements of paragraph (i) of section (a)(2) has been made. October 30, 2017 Jason M. Stratton, P.E. Date

3 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant TABLE OF CONTENTS PROFESSIONAL ENGINEER CERTIFICATION...II 1.0 INTRODUCTION EXISTING CONDITIONS BASIS FOR HAZARD POTENTIAL CLASSIFICATION Dam Breach Analysis Dam Breach Inundation Analysis Guidance Modeling Assumptions Breach Scenarios Breach Parameter Estimation Downstream Routing Existing Channel Flow Flood Inundation Topography Conclusions...5 SOURCE(S)...6 REVISIONS...7 FIGURES Figure 1. Site Vicinity...8 Figure Froehlich Breach Perameters...9 Figure Dam Breach Inundation Map i October 30, 2017

4 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant 1.0 INTRODUCTION The PacifiCorp Naughton Power Plant is located approximately three miles southwest of Kemmerer, Wyoming. This report addresses the requirements of (a)(2) Periodic Hazard Potential Classification Assessments, as it pertains to FGD Pond 5 at the Plant. FGD Pond 5 constructed in This report presents the initial evaluation immediately following completion of construction and prior to the pond being placed into service. The hazard potential classification for the FGD Pond 5 was determined to be significant. The date of this initial classification was October 1, Periodic hazard potential classification assessments will be completed every five years following this initial assessment. 2.0 EXISTING CONDITIONS The Naughton Power Plant is located approximately 3 miles southwest of Kemmerer, Wyoming. The Plant consists of three coal-fueled units, rated with a net dependable capacity of 156 MW, 201 MW, and 330 MW, respectively. Coal combustion by-products at the Plant include several types of materials including bottom ash, fly ash, and FGD materials. FGD Pond 5 was constructed in 2017 at the location shown on Figure 1. The pond has a permitted capacity of 1,467 acre-ft which is expected to provide approximately 10 years of disposal capacity. The pond may remain operational when full to allow additional evaporation of water. As water evaporates, additional effluent may be added eventually filling the pond with solids. When filled with solids or when continued operation is no longer feasible, a cover will be constructed and the pond will be permanently closed. The pond has a surface area of 49 acres at the crest with a maximum interior depth of 46 ft. The pond is located on a topographically high area with surface water drainage away from the pond in all directions. The only source of water or waste entering the pond is through two effluent delivery pipelines as well as any precipitation falling within the pond area. No surface water run-on is allowed to enter the pond. The pond has no discharge outlets or spillways (all water entering the pond will be evaporated). The pond embankments have 3 horizontal to 1 vertical slopes and was constructed using soil excavated from within the pond limits and an adjacent borrow area. The pond foundation materials consist of stiff clay and claystone bedrock. Permanent ballast consisting of grout filled tubes was placed over the geomembrane to prevent wind damage. A chain link security fence was installed around the pond to prevent larger wildlife from entering the area. A bird hazing system was installed to reduce impacts to migratory water fowl. The pond was constructed with a composite liner system consisting of a 60-mil HDPE geomembrane (upper component) in direct contact with a two-foot layer of compacted soil with a hydraulic conductivity of no more than 1 x 10-7 cm/sec (lower component). 3.0 BASIS FOR HAZARD POTENTIAL CLASSIFICATION The conclusion of this periodic hazard potential classification assessment is a significant hazard potential classification is appropriate for FGD Pond 5. This hazard assessment utilized the Federal Guidelines for Dam Safety - Hazard Potential Classification System for Dams (FEMA, 2004). The table shown below lists the FEMA classification levels relative to the applicable damage criteria. [2] : October 30, 2017

5 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant Hazard Potential Classification Loss of Human Life Economic, Environmental, Lifeline Losses Low None expected Low and generally limited to owner Significant None expected Yes High Probable. One or more expected Yes (but not necessary for this classification) The pond cannot be classified as having a Low hazard potential because a complete failure of an embankment has a high likelihood of resulting in a release of CCR waste resulting in economic and environmental loss. A dam breach analysis and inundation mapping is presented below. A review of the potential inundation area indicates there is no probable loss of human life in the event of a complete failure of an embankment occurs. The area downstream of the dam that would be inundated in a breach is unoccupied rural property with no residences, worksite areas, or other areas of permanent human occupancy. Because there is potential for economic, environmental, and lifeline losses but loss of human life is not probable, FGD Pond 5 does not qualify as a High hazard potential structure and should be classified as having a Significant hazard potential. 3.1 Dam Breach Analysis The proposed FGD Pond 5 embankments at the Naughton Power plant near Kemmerer Wyoming were evaluated in order to characterize and identify threats to the public, environment, and property due to potential dam failures. This analysis serves to determine the maximum flood-water flows, velocities, floodwave arrival times, elevations, and impacted areas. The following section is a summary of this analysis DAM BREACH INUNDATION ANALYSIS GUIDANCE The Wyoming State Engineer s Office does not provide specific guidance for dam breach analyses. Due to the high risk associated with dam breaches, it is recommended that a conservative approach is taken and that several methods are evaluated to provide a thorough range of results. The following breach analysis guidance documents were evaluated for this analysis: United States Bureau of Reclamation s (USBR) Design of Small Dams, Chapter 13: Dam Safety (1987); Colorado Office of the State Engineer, Dam Safety Branch s Guidelines for Dam Breach Analysis (2010); Washington State Department of Ecology s Dam Safety Guidelines: Technical Note 1 - Dam Break Inundation Analysis and Downstream Hazard Classification (2007). October 30, 2017

6 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant The Wyoming State Engineer s Office recommended the USBR guidance which outlines the Envelope Curve Equation for impoundments with hazard classifications of significant or less. The equation is outlined in the USBR s Design of Small Dams, Chapter 13: Dam Safety. The Envelope Equation is a conservative method that calculates a maximum breach discharge at the dam based on historic dam breach data including discharge and depth of water behind the dam at the time of failure. The Colorado and Washington documents both highlight the Macdonald & Langdridge-Monopolis and Froehlich (2008) methods for calculation of breach parameters. Washington State improved the Macdonald & Langdridge-Monopolis method by adjusting it to account for either cohesive or cohesionless dam materials. This method is referred to as the Washington State Method. Colorado provides two spreadsheets to supplement their guidance document which can be used to calculate breach parameters for piping or overtopping failures using either the Washington State or Froehlich (2008) methods. Table 3 of Colorado s Guidelines for Dam Breach Analysis (2010) is shown in Figure below and provides a guide of the most appropriate empirical breach parameter methods to use based on various dam sizes and storage-intensities. Figure State of Colorado - Guide of Appropriate Empirical Methods for Various Dam Sizes and Storage- Intensities FGD Pond 5 is considered a Small Dam. The storage-intensity (SI) is calculated as the volume of water (V w) divided by the height of the water (H w) behind the dam. FGD Pond 5 has an estimated maximum October 30, 2017

7 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant volume of 1,467 acre-feet with a maximum height of 45 feet. These inputs result in a Storage Intensity of 32.6 and is considered a high storage-intensity. From Table 3, dam breach analyses for Small Dams with a high storage-intensities should use the Froehlich (2008) empirical method to calculate breach geometry and failure time. Colorado states that the Froehlich (2008) Method yields conservative, but reasonable results for Small dams with >100 acre-feet of storage MODELING ASSUMPTIONS FGD Pond 5 was designed as a storage facility. It does not impound any stream flow and is subject only to inflow from the Naughton Power Plant and from rainfall within its extents. Additionally, FGD Pond 5 is a zero discharge facility without any outlet structures BREACH SCENARIOS FGD Pond 5 is comprised of several embankment sections that could be modeled in a dam breach analysis. A breach was assumed to occur on the eastern embankments releasing liquids directly into an un-named drainage and to an existing culvert under County Road 304 (Elkol Road) and into the mild sloped North Fork Little Muddy Creek. This breach analysis considers sunny day embankment failure due to piping. Due to the three feet of available freeboard and negligible upland drainage areas, an overtopping failure resulting from a significant rainfall event is highly unlikely. Therefore, this analysis does not consider overtopping failure BREACH PARAMETER ESTIMATION Breach parameters were calculated by the Froehlich (2008) Method using a spreadsheet provided by the State of Colorado. Figure summarizes the input parameters, breach characteristics, and results check. The predicted peak flow calculation is based on an equation developed for the Simplified DAMBREAK program by Wetmore & Fread in DOWNSTREAM ROUTING Downstream routing analysis is necessary to determine the behavior of the flood wave in various channel reaches and critical sections downstream. Behavior includes attenuation, travel time, maximum water elevation, and change in shape of the flood hydrograph. The U.S. Army Corps of Engineers HEC-RAS software was used to model flood inundation for a breach and are shown on the following figure EXISTING CHANNEL FLOW The flood wave then will meander through the wide, mild-sloping floodplain of North Fork Little Muddy Creek. This flood plain passing through an existing railroad and US 189 through existing culverts. The North Fork Little Muddy Creek then parallels another railroad and turns south east to parallel State Road 412 where the creek exits the area of analysis. Average base flow conditions in North Fork Little Muddy Creek were investigated in order to determine the maximum permissible dam breach flow that the culvert could handle. There are no known streamflow gauges on North Fork Little Muddy Creek. Average flows are reported to be minimal from observations on site. For this exercise, an average flow of cfs was assumed in North Fork Little Muddy Creek. Therefore, during average flow conditions the culvert likely would not handle an additional 39,943 cfs resulting from a dam breach. October 30, 2017

8 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant FLOOD INUNDATION TOPOGRAPHY The topography used in this breach analysis was obtained from the following sources: FGD Effluent Disposal Pond 5 Plan Final Grade Alternate 1 designed by Tetra Tech in Naughton FGD5 Topography June 2016 Pt. Sec 1&12, Resurvey of T. 20N., R117W. performed by Crank Companies Incorporated. USDA/NRCS National Geospacial Center of Exellence USGS National Elevation Data (NED) 10 meter elevations. The following assumptions were also made: Annual (low flow) channel was not available in the USGS contour information, and it was not included in this analysis; Highway, roadways, railroad, and plant site were not available in the USGS contour information, and were not included in this analysis; Reduction in peak discharge due to inundation is not included in this analysis; Information on culvert and bridge crossings along the channel was not provided, and these were not included in this analysis; Manning s roughness coefficient selection for channel was based on aerial images; A topographic surface was built in AutoCAD Civil3D 2014, and a channel alignment was derived from the USGS centerline of the North Fork Little Muddy Creek. Cross-sections were evaluated every 500 feet along the creek. Manning s equation for open channel flow was used to calculate peak flow depths at each section. A Manning s number of n = was selected from Table 4-1 of Open Channel Hydraulics by Terry W. Sturm (2001). This value corresponds to major streams with top widths at flood stage > 100 feet and irregular and rough sections CONCLUSIONS The inundation mapping does not indicated any permanently occupied structures would be inundated in the area downstream from FGD Pond 5 in the case of a dam breach. October 30, 2017

9 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant SOURCE(S) [1] USEPA, CFR Parts 257 and 261, Hazardous and Solid Waste Management System; Disposal of Coal Combustion Residuals from Electric Utilities; Final Rule. April 17, pp. [2] FEMA Federal Guidelines for Dam Safety Hazard Potential Classification System for Dams. April, pp. [3] US Bureau of Reclamation, Design of Small Dams pp. October 30, 2017

10 Design Criteria (a)(2) Periodic Hazard Potential Classification PacifiCorp Naughton Power Plant REVISIONS Revision Number Date Revision Made By Whom 0 10/30/2017 Initial Issue Tetra Tech October 30, 2017

11 MONTANA POWELL LOVELL SHEDIDAN NEW EFFLUENT PIPELINE SEC. 1 SEC. 6 IDAHO CODY GREYBULL SUNDANCE BUFFALO GILLETTE BASIN MOORCROFT WORLAND TEN SLEEP MORAN NEWCASTLE THERMOPOLIS DUBOIS LINCH JACKSON MIDWEST SHOSHONI LANCE CREEK FORT WASHAKIE EVANSVILLE PINEDALE RIVERTON GLENROCK LUSK LANDER CASPER AFTON DOUGLAS BIG PINEY SUNRISE TORRINGTON SOUTH DAKOTA NEBRASKA KEMMERER EDEN HANNA MEDICINE BOW WHEATLAND GREEN RIVER RAWLINS MOUNTAIN LYMAN VIEW EVANSTON ROCK SPRINGS SARATOGA LARAMIE ORCHARD VALLEY CHEYENNE UTAH KEY MAP COLORADO R:\N-S\PacifiCorp\ Naughton FGD Pond\110-2D CADD\SheetFiles\01-Vicinity Map.dwg SAVED:1/12/17 PRINTED:1/12/17 BY:MARK.COOK NEW FGD POND 5 ACCESS ROAD Three Crowns Drive, Suite 210 Casper, WY NEW FGD EFFLUENT DISPOSAL POND 5 3 SEC This Drawing, in the form transmitted, is the original work product of TETRA TECH. This drawing cannot be altered, revised or reproduced without the prior written consent of TETRA TECH. An original will be retained by TETRA TECH as the "record copy" for purposes of this project. TETRA TECH does not approve of or warrant these documents if any alteration or modification is made without TETRA TECH's written approval. 4 5 CO. RD. 304 (ELKOL ROAD) Point # POINT COORDINATES Northing 780,549.81' 780,840.84' 780,705.88' 780,313.29' 779,532.25' 779,251.20' 779,298.33' 779,615.00' Easting 2,485,709.83' 2,485,938.61' 2,486,941.83' 2,487,845.06' 2,487,921.40' 2,487,426.65' 2,485,988.22' 2,485,679.07' All point coordinates are in the NAD83 Wyoming State Planes, West Zone, US Foot datum. 0 Feet 500 January 12, 2017 FIGURE 1 FGD EFFLUENT DISPOSAL POND 5 NAUGHTON POWER PLANT KEMMERER, WYOMING SITE VICINITY

12 R:\N-S\PacifiCorp\ Naughton FGD Pond\110-2D CADD\SheetFiles\ Froehlich Breach Figure.dwg SAVED:1/13/17 PRINTED:1/13/17 BY:MARK.COOK Source: This Drawing, in the form transmitted, is the original work product of TETRA TECH. This drawing cannot be altered, revised or reproduced without the prior written consent of TETRA TECH. An original will be retained by TETRA TECH as the "record copy" for purposes of this project. TETRA TECH does not approve of or warrant these documents if any alteration or modification is made without TETRA TECH's written approval. January 13, 2017 FIGURE FGD EFFLUENT DISPOSAL POND 5 NAUGHTON POWER PLANT KEMMERER, WYOMING FROEHLICH BREACH PERAMETERS

13 February 10, 2010 Guidelines for Dam Breach Analysis Table 4 Summary of Macdonald & Langridge-Monopolis and Washington State Spreadsheet Calculations by Embankment Type Calculation of Breach Embankment Development Embankment Type Reference Volume Eroded Time (V er ) (T f ) Macdonald and Langridge- Earthen (Cohesive) Monopolis (1984) & Washington State (2007) Earthen (Cohesionless) Washington State (2007) Rockfill Macdonald and Langridge- Monopolis (1984) & Washington State (2007) As discussed in Section above, a piping failure may result in reservoir evacuation prior to full breach development. To address this failure mode, the spreadsheet includes a feature to calculate piping hole dimensions. The size of the piping hole, which is assumed to be square, is calculated based on the embankment volume eroded (V er ) and the dam geometry. The peak discharge through the piping hole is then calculated using the orifice equation. The calculation assumes that the piping hole forms instantaneously by applying the head of a full reservoir. This conservative assumption is considered adequate for a screening level analysis. Froehlich 2008 Spreadsheet The Froehlich 2008 spreadsheet was developed according to the relationships proposed by Froehlich (2008). Using this method, breach dimensions are dependant only on the depth and volume of water stored by the dam. This method does not consider dam geometry or the type of soil used to construct the dam. The average breach width (B avg ) and failure time (T f ) are calculated as: Where: = Failure Mode Factor = Height of breach in feet = Reservoir volume stored in acre-feet The spreadsheet automatically selects the K o value based on the user-selected failure mode. The values are 1.0 and 1.3 for piping and overtopping failures, respectively. The spreadsheet allows the user to input the breach side slope ratio, but it should be noted that Froehlich recommended values of 0.7 and 1.0 for piping and overtopping failures, respectively. 18

14 Guidelines for Dam Breach Analysis February 10, Physically Based Models NWS BREACH is currently the most widely used physically based model that can be used to estimate dam breach parameters. Based on Colorado Dam Safety Branch research into the BREACH program for numerous case studies (see Appendix A), the following potential problems have been identified and should be considered when using BREACH to estimate dam breach parameters: 1. Back-calculation of the piping orifice coefficient from BREACH output runs indicate the program may over-estimate this coefficient within BREACH vs. hand-calculated values based on equations developed by Fread (1988b). This problem appears to result in an over-estimation of breach flows for some Small and Minor dams with low storage intensities and an under-estimation of breach flows for dams with higher storage intensities. 2. The program causes the transition from pipe to weir flow to occur when the reservoir level reaches one-half of the pipe height above the top of the pipe. In other words if the piping hole height is 10 feet, then the crest collapses when the reservoir is 5 feet above the top of the piping hole. Based on observed dam failures of minor sized dams, this appears to force the collapse to occur prematurely. When combined with the high piping orifice coefficient, this issue may tend to drain the reservoir too rapidly and result in a smaller final breach configuration (less conservative). 3. After the crest collapses, the breach section gradually erodes laterally until the reservoir is drained enough to halt additional erosion. BREACH does not consider the head-cutting potential, so the lateral erosion may be overly simplified and the erosion rate is slow during this portion of the simulation. This may tend to make the total failure time long (less conservative). 4. The modeling algorithm for an overtopping failure erodes through the downstream slope and crest at the same grade as the downstream embankment slope using a sediment transport equation. Once the crest is eroded, the program starts eroding downward through the upstream slope, which, at the beginning erodes very rapidly straight down to the bottom of the dam without widening. Once the breach is cut through the dam, the program widens the breach at a slow rate. This algorithm ignores the head-cutting erosion process that actually occurs during an overtopping failure and results in a final breach configuration that may tend to be narrow (less conservative). These limitations should be taken into account when BREACH is used for performing hazard evaluations. BREACH appears to be most applicable for Small or Minor dams with low storage intensities since the alternative methods (empirical equations) sometimes yield very small breach dimensions and failure times. Acceptance of this model for hazard classification studies will be allowed with reasonable justification. The results must be validated with the other recommended methods. 7.2 Breach Peak Discharge Estimation Empirical Methods Equations for breach peak discharge estimates were developed for both the MacDonald & Langridge- Monopolis (1984) and Froehlich (2008) methods. Wahl evaluated these equations by comparing predicted peak discharges to actual peak discharges and found significant scatter between observed data and that predicted by the equations. The Froehlich equation had the best correlation, but still could significantly over-predict or under predict the peak flow. The MacDonald & Langridge-Monopolis method is an outlier curve with significant scatter and appears to greatly over predict the peak flow. In several analyses performed with this guideline, it was determined that the MacDonald & Langridge- Monopolis equation produced peak flows significantly greater than that produced by an instantaneous failure to the ultimate breach geometry. In other words, the computed peak discharge using a weir flow 19

15 February 10, 2010 Guidelines for Dam Breach Analysis equation with the final breach configuration and the reservoir level at H w was less than that produced by the MacDonald & Langridge-Monopolis peak discharge equation, which is impossible unless the reservoir is infinitely large. Wetmore and Fread (1984) provide an alternative to the MacDonald & Langridge-Monopolis (1984) and Froehlich (2008) equations for breach peak discharge. This equation was developed as part of the Simplified DAMBRK program (SMPDBK). It is essentially a weir equation of an instantaneous failure with a reduction factor. This reduction factor is dependent upon the reservoir surface area at full storage, the failure time, and H w. As the size of the reservoir increases, this equation appropriately approaches that of an instantaneous failure and the peak flow will never exceed the instantaneous failure value. Because of the weir flow component of this equation, it is more physically based than a pure empirical equation. The breach dimensions can be determined with empirical models, and then those dimensions can be input into this equation to determine a predicted peak discharge. The equation is as follows: Where: Q p = Dam break peak discharge in cfs B avg = Average breach width in feet H w = Maximum depth of water stored behind the breach in feet T f = Breach development time in hours = Instantaneous flow reduction factor A s /B avg (equivalent to in Wetmore and Fread (1984)) A s = Surface area of the reservoir in acres corresponding to H w In several of the case studies analyzed in the preparation of this guideline, the predicted Q p using the SMPDBK equation was greater than the actual computed peak flows using HECRAS, but the difference was marginal. As such, the SMPDBK Peak Flow Equation tends to produce reasonably conservative results. These equations provide only peak discharge values as opposed to a hydrograph. In cases where routing of the flow is not considered or predicted empirically, this equation can be used as part of a Screening level analysis and can indicate if a more sophisticated analysis is needed. For instance, if the SMPDBK equation produces a peak discharge that shows the critical structure is clearly not inundated, then the dam can be rated as Low Hazard and further work to determine a High or Significant Hazard rating is not warranted. If the estimated peak discharge from the SMPDBK equation clearly inundates the structure, then the dam should be rated as either High or Significant Hazard unless a more sophisticated analysis shows that a lower hazard class is appropriate. In cases where the piping failure mode is not expected to progress to a full breach, the weir flow assumption of the SMPDBK equation above does not apply. In this case, a theoretical maximum breach discharge can be calculated with the orifice equation assuming that the piping hole opens to its maximum dimensions instantaneously: Where: 20

16 9. Under section Figure is not legible. All of the input data, the actual model information including equations used and all of the model output data must be submitted for Figure The coordinates for the outer boundaries of the inundation mapping must be indicated on a drawing and submitted in a Table. Response: Figure had been reformatted to 11x17. All input data, equations, and model output has been presented following the figure. Coordinates have been added to the figure and presented in a table.

17 SOUTH ASH POND FGD 4 POND FGD POND 5 0 Feet 5000 LEGEND GENERAL NOTES INUNDATED AREA 1- CONTOUR DATA INSIDE LIMITS OF SURVEY LINE BASED ON "NAUGHTON FGD5 TOPOGRAPHY - JUNE 2016 PT. SEC 1&12, RESURVEY OF T.20N, R117W." PERFORMED BY CRANK COMPANIES INCORPORATED 2- CONTOUR DATA OUTSIDE LIMITS OF SURVEY LINE BASED ON 2000 USDA/NRCS CONTOUR INFORMATION. THESE CONTOURS MAY NOT REFLECT CURRENT SITE CONDITIONS. 3- ROADWAY, RAILROAD, BRIDGE CROSSING, CULVERT INFORMATION, AND OTHER SITE FEATURES WERE NOT INCLUDED IN THIS ANALYSIS. NAUGHTON FGD 5 PRELIMINARY DAM BREACH INUNDATION MAP Bar Measures 1 inch Copyright Tetra Tech 11/11/ :01:00 AM - S:\N-S\PACIFICORP\ NAUGHTON FGD POND\19-CIVIL-SITE-SERV\DAM BREACH\DAM BREACH HEC-RAS\NAUGHTON FGD 5 ININDATION MAP.DWG - COOK, MARK LIMITS OF 2016 SURVEY

18 HEC-RAS Plan: FGD 5 Breach River: FGD 5 Breach Mod Reach: Channel Profile: PF 1 Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl (cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF

19 HEC-RAS Plan: FGD 5 Breach River: FGD 5 Breach Mod Reach: Channel Profile: PF 1 (Continued) Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl (cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel PF Channel 8500 PF Channel 7500 PF Channel 6500 PF Channel PF Channel 5500 PF Channel 5000 PF Channel 4000 PF Channel 3000 PF Channel 2500 PF Channel 2000 PF Channel 1500 PF

20 FGD 5 Dam Breach Plan: FGD 5 Breach Model 1/13/2017 FGD 5 Breach Mod Channel Main Channel Distance (ft) Legend EG PF 1 WS PF 1 Crit PF 1 Ground Elevation (ft)