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HomeMy WebLinkAbout03.05 Binder 2 - Appendix FHopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development PREPARED FOR: Michael Gamba, P.E. & P.L.S. Gamba & Associates, Inc. 113 Ninth Street Suite 214 Glenwood Springs, CO 81601 Wright Water Engineers, Inc. October 2007 931-004 040 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development PREPARED FOR: Michael Gamba, P.E. & P.L.S. Gamba & Associates, Inc. Prepared by: WRIGHT WATER ENGINEERS, INC. Glenwood Springs, Colorado October 2007 931-004.040 TABLE OF CONTENTS Page 1.0 PURPOSE 1 2.0 SUMMARY 2 3.0 METHODOLOGY 4 3.1 Breach Parameter Estimation 4 3.2 Hydrograph Development 6 3.3 Hydrograph Routing 6 4.0 HYDRAULIC MODELING 8 4.1 Geometric Data 8 4.2 Energy Loss Coefficients 8 4.3 Hydraulic Structures 9 4.4 Hydraulic Model Results .......................... 9 5.0 CONCLUSIONS 10 1 Hopkins Reservoir Stage -Storage 2 Breach Size Calculations 3 Routing Assumptions and Results 4 Tabulation of Hydraulic Model Results TABLES FIGURES 1 Study Area Location Map 2 Hopkins Reservoir Stage -Storage Curve 3 Breach Formation Illustration 4 Breach Formation Relationship 5 Dam Breach Hydrograph MAPS 1 Hopkins Reservoir Dam Breach Inundation Map APPENDICES A Calculation of Dam Breach Parameters B Dam Breach Calculations C Hydraulic Model Results ii Hopkins Reservoir DamBreak Analysis • Spring Valley Ranch Planned Unit Development 1.0 PURPOSE Wright Water Engineers, Inc. (WWE) has performed a dam break analysis for an enlargement of the Hopkins Dani and Reservoir located within the Spring Valley Ranch Planned Unit Development. Pursuant to the Board of County Commissioners (BOCC) Resolution No. 2005- 84, Spring Valley Ranch, Inc. must asses the effects of a darn failure with respect to the subdivision drainage plan in order to prevent potential loss of life and damage to structures. This report addresses the methodology used to estimate the flows resulting from a potential dam failure event and the hydraulic modeling of the peak flows between Hopkins Reservoir and Spring Valley (study area). The hydraulic model provides water surface elevations, which are mapped to delineate the inundation area. Gamba and Associates, Inc. can use the inundation delineation and hydraulic model results as planning tools for subdivision development. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 1 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 2.0 SUMMARY The Hopkins Dam embankment is an existing structure located in Section 15, Township 6 South, Range 88 West of the 6l' Principal Meridian and is shown in Figure 1. The basin tributary to Hopkins Reservoir is approximately 332 acres, or 0.52 square miles (Figure 1). The existing and enlarged Hopkins Reservoir storage volumes are approximately 119 and 233 acre-feet, respectively. Thus, the enlarged Hopkins Reservoir represents a 96 -percent increase in storage capacity from the existing reservoir. See Table 1 for the existing and enlarged stage -storage relationships for Hopkins Reservoir. The information in Table 1 is presented graphically in Figure 2. Preliminary plans for the enlarged Hopkins Reservoir include excavating material from the existing reservoir site in addition to raising the embankment crest height from 20 feet to 24 feet. References to the Hopkins Dam and Hopkins Reservoir in the remainder of this report are intended to refer to the enlarged characteristics mentioned above. The potential hazard area resulting from the failure of Hopkins Dam is limited to three distinguishable reaches between Hopkins Reservoir and Spring Valley: 1) The existing natural channel, approximately 700 feet long between Hopkins Reservoir and its junction on the left bank of Landis Creek. This is a steep, relatively undefined intermittent drainage channel. 2) The approximately 3 -mile long reach of Landis Creek beginning at the terminus of Reach 1) and ending at County Road I 1 5. A steep, incised channel characterizes this portion of Landis Creek. 3) The area between County Road 115 and the Spring Valley bottom. This reach represents the alluvial fan created by Landis Creek as it merges with Spring Valley. Reference Figure 1 for the locations of the reaches described above. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 2 • Hopkins Reservoir Dam Break Analysis Spring Valley RanchPlanned Unit Development It should be noted that to date a final design for an enlarged Hopkins Dam and Reservoir has not been completed. However, Gamba and Associates, Inc. have previously performed preliminary evaluations that have resulted in set criteria for heightening the embankment and excavating material from the existing reservoir. Any enlargement above and beyond the embankment height and reservoir volume mentioned herein is not covered in this report. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 3 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 3.0 METHODOLOGY WWE evaluated a "sunny day" scenario as the failure event of the Hopkins Dam. The "sunny day" scenario assumes a sudden breach of the dam embankment and does not add additional flows resulting from extreme precipitation events to the dam breach hydrograph. Sediment loading was not considered in the analysis. For the purposes of this study, WWE assumed "worst case" scenarios for the development of the dam breach hydrograph: Failure Event Assumptions 1) The failure mechanism is breaching of the dam embankment.' 2) The final breach height extends downward from the crest to the toe of the dam embankment, effectively draining the entire reservoir storage volume. 3) The reservoir stage is at full capacity at the time the breach begins to form. These assumptions are representative of a complete and catastrophic failure event resulting in the highest peak flows for a "sunny day" dam break scenario. 3.1 Breach Parameter Estimation WWE implemented equations developed by David C. Froehlich to estimate the dant breach parameters. The primary parameters of interest are the breach formation time and the breach size. The Froehlich equations were developed using regression equations based on darn failure event case studies. The majority of the case studies involved earthen dam embankments ranging from 20 to 50 feet in height. Breaching of the dam embankment was chosen due to its more sudden nature resulting in higher peak flows escaping the reservoir relative to other failure mechanisms, such as piping. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 4 Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development While nutnerous references exist for estimating breach parameters and peak flood flows resulting from dam failures, the Froehlich equations were chosen for the following reasons: 1) The discharge resulting from a breach can be modeled using simplifying hydraulic assumptions since the stage -storage relationship for the Hopkins Reservoir is known. 2) The case studies on which the equations were developed are representative of the Hopkins Dam. 3) The equations are comprised of variables dependent on the dam embankment geometry and storage capacity, both of which are known. Using the Froehlich equations, a breach formation time of 20 minutes and a final breach base width of 43.5 feet were calculated. See Appendix A for calculations of the dam breach parameters. WWE assumed the breach formation begins at the top of the dam embankment crest. The breach then becomes larger due to erosion forces and progressively widens and deepens during the 20 - minute breach formation time. Figure 3 provides an illustration of the breach formation. A sinusoidal breach formation progression was used to calculate the breach geometry between zero and 20 minutes. Figure 4 provides a graph of the breach formation relationship. After 20 minutes has elapsed, the breach formation is complete. See Table 2 for calculations of the breach size. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 5 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 3.2 Hydrograph Development The flow out of the reservoir through the breach is a function of the reservoir stage and the breach size. The flow rate, Q, was calculated using the broad crested weir equation, Q= C„.LH.ai2 where C„. is a known constant, L is the width of the spillway crest corresponding to the breach base width, and H is the static head above the spillway crest corresponding to the height of water above the base of the breach. The weir assumption is appropriate because velocities in the reservoir can be assumed to be negligible and the primary factor influencing flows is the height of water above the base of the breach. Reference Appendix B for the calculations of reservoir stages, volumes, and flows used to develop the dam breach hydrograph. The dam breach hydrograph is presented in Figure 5. 3.3 Hydrograph Routing Attenuation of the dam breach hydrograph was accomplished with the use of HEC -HMS. Approximations of the channel geometry at flood stages were made. A Manning's n roughness coefficient of 0.08 was used to approximate the channel characteristics throughout the entire reach.2 WWE examined the channel geometry and grouped the study area into eight reaches based on the cross-section channel geometry and channel slope. Data for these eight reaches were entered into HEC -HMS and the darn breach hydrograph was then routed. ' In HEC -RAS modeling, a Manning's n of 0.04 is used for the channel and a Manning's n of 0.08 is used for overbank areas. Since the relatively small Landis Creek channel (n=0.04) constitutes only a small fraction of the wetted perimeter at flood stages, the Manning's n for the overbank (n=0.08) was used for hydrograph routing. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 6 • • • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development Based on the HEC -HMS results, attenuation of the flood wave as it travels through the study area was minimal. The peak flow at County Road 115 is delayed 7 minutes and is 300 cfs lower than the dam breach hydrograph. This can be expected as channel characteristics through the affected corridor are predominantly very steep and narrow with average slopes exceeding 10 percent and 7 percent throughout the upper and lower reaches, respectively, of Landis Creek. Flow in HEC - RAS defaults to critical depth at most cross-sections. Table 3 summarizes the channel geometry assumptions implemented for routing purposes and the subsequent HEC -HMS results including the time to peak and peak flow rate. 931-004.040 October 12, 2007 Wright Water Engineers, inc. Page 7 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 4.0 HYDRAULIC MODELING The HEC -RAS v. 3.l .3 software was used to perform the hydraulic modeling for the study area. HEC -RAS is a one-dimensional hydraulic model used to calculate water surface elevations associated with specified flows. The program utilizes the standard step backwater method for balancing the energy equation to compute a water surface at a cross section. Standard conventions with HEC -RAS are for the cross sections to be numbered from downstream to upstream and for cross sections to be viewed looking downstream. 4.1 Geometric Data Gamba and Associates, Inc. provided topographic data used to assemble the hydraulic model. Cross sections spacing was approximately 200 feet throughout the study area. Using Geographic Information System (GIS) software, geometric cross sections were created at each cross section location and imported in to HEC -RAS. See Map 1 for the cross section locations. 4.2 Energy Loss Coefficients Channel and over bank characteristics were consistent through the study area. Manning's n values in the over bank areas along Landis Creek were set to 0.080 to account for the trees and shrubs found beyond the channel. A Manning's n value of 0.040 was chosen to represent the channel characteristics of Landis Creek throughout the entire study reach as well as the over bank areas downstream from County Road 115. Standard contraction and expansion loss coefficients (0.10 and 0.30) were used to account for variations in geometry between cross-sections. Additional energy loss coefficients were not incorporated in the hydraulic model. 931-004.040 October 12, 2007 Wright Water Engineers, Inc, Page 8 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 4.3 Hydraulic Structures Three small earth embankment dams exist within the study reach. Two of these are located within the Wing out -parcel. All of the dams were modeled as broad crested weirs with the crest elevations set equal to the dam embankment crest elevations. Due to the small capacity of the storage areas for each of the dams, additional attenuation of the dam breach hydrograph attributable to the dams was not accounted for in the hydraulic model. 4.4 Hydraulic Model Results Once the model geometry was constructed based on the imported cross sections, the roughness coefficients were entered into the program. The hydraulic structures were then incorporated into the model. Finally, the attenuated peak flows were entered into the model based on the hydrograph routing results developed with the use of HEC -HMS and summarized in Table 3. The final model results are presented in Table 4. The extents of inundation caused by the dam breach were delineated based on the water surface elevations and topography at each cross section. The inundation area is shown in Map I. Appendix C includes plots of each model cross section and the accompanying water surface elevation. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 9 • Hopkins Reservoir Dam Break Analysis Spring Valley Ranch Planned Unit Development 5.0 CONCLUSIONS Landis Creek comprises the majority of the study area. Flows resulting from the dam breach are confined within the steep, narrow confines of the Landis Creek corridor. Subdivision plans should not include structures located within the inundation area as depicted in Map 1. Where feasible, road alignment should be outside of the extents of inundation as well due to the high velocities of the flood wave shown in Table 4. Where roads are planned to cross areas of inundation shown on Map 1, it will be necessary to evaluate the potential for backwater inundation of nearby structures and to provide for stable conveyance of flows over the road. The area of inundation downstream from County Road 115 is approximate due to the broad, gently sloping topography exhibited in the area.3 The majority of flooding in this area will be characterized by shallow water depths and/or braided flow!' c-: WORK`WWF;:931-004'.040hrkiHopkins Res. Dam Break Report'IIopkins_Dam_ Brea k_Analysis _Repon.doe ' This arca is comprised of the Landis Creek alluvial fan. a Extreme caution should be used when locating structures in this area and avoided if possible. Additionally. the Landis Creek alluvial fan arca could potentially be at risk of flooding resulting from runoff caused by extreme precipitation events. 931-004.040 October 12, 2007 Wright Water Engineers, Inc. Page 10 TABLES TABLE 1 Hopkins Reservoir Stage -Storage Existing and Enlarged Elev, (ft) Stage (ft) Existing Volume (acre-feet) Enlarged Volume (acre-feet) 8976.0 0.0 0.0 0.0 8978.0 2.0 0.8 0.8 8980.0 4.0 3.5 10.0 8981.0 5.0 6.1 18.5 8982.0 6.0 8.7 27.2 8983.0 7.0 12.6 36.3 8984.0 8.0 16.5 45.6 8985.0 9.0 21.8 55.2 1 8986.0 10.0 27.1 65.0 8987.0 11.0 33.8 75.2 8988.0 12.0 40.4 85.6 8989.0 13.0 48.4 96.3 8990.0 14.0 56.3 107.3 8991.0 15.0 65.6 118.5 8992.0 16.0 74.8 130.1 8993.0 17.0 85.3 141.9 8994.0 18.0 95.7 154.1 8995.0 19.0 107.2 166.6 8996.0 20.0 118.7 179.3 8997.0 21.0 - 192.4 8998.0 22.0 - 205.7 8999.0 23.0 - 219.4 9000.0 24.0 - 233.4 Notes: Hopkins Reservoir stage -storage curve based on preliminary drainage plan information received from Gamba and Associates, Inc. dated 12-11-01. E:1Projects1W W E1931-0041 040jaw1Dam_Breach.xls :fright' Winer Engineers, Inc. Des. By: JAW Ckd.By: DMJ 10112/07 • • • TABLE 2 Breach Size Calculations Time (min) (1) Time (% of t{) (2) Breach I Formation (%) (3) Base of Breach Elev. (ft)( (4) Base of Breach Reservoir Stage ft) (5) Base width of Breach (ft) (6) 0 0% 0.00% 9000.0 24.0 0.0 1 5% 0.62% 8999.9 23.9 0.3 2 10% 2.45% 8999.4 23.4 1.1 3 15% 5.45% 8998.7 22.7 2.4 4 20% 9.55% 8997.7 21,7 4.2 5 25% 14.64% 8996.5 20.5 6.4 6 30% 20.61% 8995.1 19.1 9.0 7 35% 27.30% 8993.4 17.4 11.9 8 40% 34.55% 8991.7 15.7 15.0 9 45% 42.18% 8989.9 13.9 18.3 10 50% 50.00% 8988.0 12.0 21.8 11 55% 57.82% 8986.1 10.1 25.2 12 60% 65.45% 8984.3 8.3 28.5 13 65% 72.70% 8982.6 6.6 31.6 14 70% 79.39% 8980.9 4.9 34.5 15 75% 85.36% 8979.5 3.5 37.1 16 80% 90.45% 8978,3 2.3 39.3 17 1 85% 94.55% 8977.3 1.3 41,1 18 90% 97.55% 8976.6 0.6 42.4 19 95% 99.38% 8976.1 0.1 43.2 20 100% 100.00% 8976.0 0.0 43.5 Notes: (1) The calculated time for the breach to form is 20 minutes (see Appendix A). (2) = Column (1)/tr, t f = 20 minutes (see Appendix A for definition of f r) (3) Sinusoidal relationship, scaled to tt. (4) = Column (3) x B bottom , Bbottom = 43.5 feet (see Appendix A for definition of B bottom) (5) = 9,000 - [Column (3) x h b ], h b = 24 feet (see Appendix A for definition of h b) (6) = h b - [h b x Column (3)] E:\Projects4W W E1931-0041 040jaw4Darn_Breach.xls Wright' !filter Engineers, Inc. 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N O M1 C) r M1 L1) (D R (0 N r -- "11- N -- Cr) eYR C3) 1- 0) C) R CO O') (0 CO M1 Lr) (D CS) (D C) M1 (t) (D LD CO M1 M1 V co Cr) M1' (0 O N C? L() CD M R L() pp CO N M1 1— (r) M1 N M1 L() N M1 M1 "4 - CN N 1 - co (1? M1 0) R C) M1 M1 N N C7 ❑O C�1 C) C7 0) (0 (_D C? M1 1() (C) R t0 N `' (0 'CY C' - M1 0) C'? M1 (D (3) N S)3 CO M1 L() co (0 C) (D O N C'? M1 11) A- LC') O C) M1 LC) o co r-- co (0 r -- CV N lrj N P- R N CV O M1 N CV N M1 C? LL? M1 0, M1 c (0 i) r (f) 10 r-- N O M1' C) C) 1- (D C3 R c0 r - R co N 0C) 0 A 0) (r) (0 O t• C) M1 N C) -r R N O tis 1. (3) co C) O M1 co co ro C7M1C) P.- co CO 1() C) 0) Lr) C) Ct (0 0) co R CO C? 0) N L0 co 0) M1 N M1 to M1 (0 N M1 CD R N R CD Lr) 4 N M1 0) CAI R (0 0) cO co co (C? Lry (D M1 (r) «J LS) r -- LC) L1) (0 0) O 1.- 0? co C) (D O 1• Da O N O M1 4 C7 co 0 M1 M1r LC) (F) Lr) (D L() 0) L() (D L1) 0) Lr)' CO Lf) 0) LC) CO Lo 0) (S`) (0 (0 CO Lr? (fl 10 CO Lr) (0 CO 1') LL? (0 co LC? (0 03 CO LC) (D 10 ("? L() (0 co Cr? co (D 03 CO (1) (D co co L0 (0 c(? co L0 u? C) co (0 ('0 C7 Lr) (D COCO CO OD CO CO CO CO l(j Lr) Lr) co co (o (o (9 CO C7 L() (D (0 co Lr) (D CO C? (r) (0 co C) u7 to O 0 O (D O O 0 0 CD O 0 C7 0 O p p 4 C7 O O (r) 07 CO R co Lh r1 co N r O N r R CC) LC) V"(") N r r r r. r- r 1 O p ' LC) L1) co 10 Lr? (tea (r) co Hopkins Dam Breach Inundation Area, for the location of model cross sections. Wright Water Engineer. • FIGURES • c Oma* o co 0 m 4t, < m —.j u _ CnCf) mZ u, m m OrnC as •7 0) mo - Qci 1 N 0 — 0 IV 0 0 — 0 0 Co v o Cn c 3 co(i) (o DJ 1. 3 0) 0 0 cn m07, Cr) N O 00) o _ o Cn (76-8 co. x -0 11) CO 0 Q - CO • N O 0 5'- O CD m (-o • m (D ID v • 0 (n 0 v kEpunO8 I Jedoad 23AS FD • q w re 0 Hopkins Reservoir Stage -Storage Curve Stage (ft) g R ▪ a c R o \ .• • • • \ • • - - - Enlarged Reservoir • % • • • • • • • •\ CO \ _ \ co § @ \ _ k $ k E C▪ O co j 0) / CO / a) cpCD & G P S S Wright Water Engineers, Inc. J _c EL) m E. CO ❑ 0 E co E w Final Breach ai a z The features shown in 7,5 • • Dam Breach Progression _c ) 45 Lo § £ E 2 / 5 $ j = S .E ( 2 / 7 C.4 \� " E § ° ® e O \ E $ $ a) @\E Qa § / \ 1- E'E /\ @ q ° « a ' 7 x a a __®� 6. " oo % $ $ 0 e 5 = e a ® 0.0 9 6 ± @ a# 2 2 7 { @ / E 4D §1-ƒa%/ƒs k, - O 3 e J a J y J E R 2 % 2 2 {eriS weals @m] uo| o� eJd) |S tae&g a5) $ )9a \ \\� 00 \ m 0 r-- (0 \ \ \0.1 0 (Fraction of Total Breach Formation Time) Wright Water Engineers, inc. 7 Q \ II tri \� c 2 /� E ®' a 200\ CO xI >� 12 -CO ) o < a_i= 0 5 - z 0 \ \ \ \ < \ 0 0 ■s 2 E E � \ 0 ®38 oa /\) \\ Wright Water Engineers, • APPENDICES • Appendix A Hopkins Dam Breach Hydrograph Calculations (Page 1 of 2) Wright Water Engineers, Inc. CALCULATION SHEET Project: Spring Valley Ranch Design: JAW Job No.: 931-004.040 Task 38 Check DMJ Date: 10/9/2007 Subject: Enlarged Hopkins Reservoir Dam Break Analysis 1. Introduction Development of the flood hydrograph resulting from a failure of the Hopkins Dam. 2. References Wahl, Tony L. July 1998. Prediction of Embankment Darn Breach Parameters. Dam Safety Research Report DSO -098-00. Bureau of Reclamation Dam Safety Office. 3. Assumptions 1. Per Gamba and Associates, Inc. stage -volume relationship for the enlarged Hopkins Reservoir, the enlarged Hopkins Reservoir has a capacity of 233 acre-feet (Figure 2). 2. Development of the flood flow hydrograph assumes a "Sunny Day Failure" of the dam embankment, i.e. inflow into the reservoir is negligible and the reservoir storage is at maximum capacity. 3. Per Gamba and Associates, Inc. stage -volume relationship for the enlarged Hopkins Reservoir, the dam embankment crest and toe elevations are 8,976 and 9,000 respectively. 4. The breach predictor equations developed by Froehlich (1995) are appropriate for estimating the breach formation time and breach width. 5. The breach formation (Fraction of Breach Time vs. Fraction of Breach Size) is sinusoidal (Figure 4). The breach formation begins at the crest of the dam and cuts to the toe of the embankment during the breach formation time. 6. The breach geometry is trapezoidal with symmetrical side slopes. The side slope factor, z (horizontal/vertical), = 1. 7. Outflows resulting from the dam breach can be calculated using the broad crested weir equation. E:\Projects1WWE1931-0041044jaw1Dam_Breach.xls Wright !eater Engineers, Inc. Des.By: JAW Ckd.By: DMJ 1013/07 Appendix A Hopkins Dam Breach Hydrograph Calculations (Page 2 of 2) 4. Breach Parameter Calculations Froehlich Breach Predictor Equations (in SI units, meters, m31s, hours) • tf= Breach Formation Time • B = Average breach width (B top +B bottom )/2 • V b., = Volume of Water above breach invert elevation at time of breach • h b = height of breach • KD =1.4 for overtopping; 1.0 otherwise • Per assumptions 1. and 2., V W = 233 acre-feet (287401 m3) • Per assumption 3., h = 24 feet (7.32m) • Per assumption 5.. K = 1.4 ■ 1. B = 0.1803K, V W 0 32h b 0.1.9 = 20.56m, or 67.5 feet 2. t f= 0.00254 V W °53h b(-° s)j = 0.331 hours, or 20 minutes ■ • Per assumption 6., B top = B bottom + 2h b 3. B = [(B bottom + 2h b) +B bottoms i2 Solving Equation 3. for B bottom where B = 67.5' yields B bottom = 43.5 feet. The value of 43.5 feet for Bbottom represents the final base width of the breach, i.e. the base width of the breach after 20 minutes. Des.By: JAW Ckd.By: DMJ E:\ProjectslWWE1931-0041040jaw1Dam_Breach.xls Wright Water Engineers, Inc. 1013!07 Appendix B Dam Breach Calculations (Pagel of 3) Time (min) Water Level Elev. (ft) Initial Re- servoir Volume (acre-feet) Fraction of Breach Size (%) Crest Width (ft) Crest Elev. (ft) Height of Water Above Crest (ft) (ft End Re. Volume (acre-feet) (1) (2) (3) (4) (5) (6) (7) (8) 0 9000.0 233.4 0.0% 0.0 9000.0 0.0 0 233.4 1 9000.0 233.4 0.6% 0.3 8999.9 0.1 0 233.4 2 8999,9 233.4 2.4% 1.1 8999.4 0.5 1 233.4 3 8999.9 233.4 5.4% 2.4 8998.7 1.2 6 233.4 4 8999.9 233.4 9.5% 4.2 8997.7 2.2 25 233.3 5 8999.9233.3 14.6% 6.4 8996.5 3.4 74 233.2 6 8999.9 _ 233.2 20.6% 9.0 8995.1 4.8 176 233.0 7 8999.9 233.0 27.3% 11.9 8993.4 6.5 358 232.5 8 8999.9 232.5 34.5% 15.0 8991.7 8.2 648 231.6 9 8999.8 231.6 42.2% 18.3 8989.9 9.9 1055 230.2 10 8999.7 230.2 50.0% 21.8 8988.0 11.7 1602 228.0 11 8999.6 228.0 57.8% 25.2 8986.1 13.5 2290 224.8 12 8999.3 224.8 65.5% 28.5 8984.3 15.0 3046 220.6 - 13 8999.0 220.6 72.7% 31.6 8982.6 16.4 3882 215.3 14 8998.6 215.3 79.4% 34.5 8980,9 17.7 4713 208.8 15 8998.2 208.8 85.4% 37.1 8979.5 18.7 5518 201.2 16 8997.6 201.2 90.5% 39.3 8978.3 19.3 6142 192.7 17 8997.0 192.7 94.6% 41.1 8977.3 19.7 6613 183.6 18 8996.3 183.6 97.6% 42.4 8976.6 19.7 6834 174.2 19 8995.5 174.2 99.4% 43.2 8976.1 _ 19.4 6772 164.9 20 8994.8 164.9 100.0% 43.5 8976.0 18.8 6524 155.9 21 8994.1 155.9 _ 100.0% 43,5 8976.0 18.1 6163 147.4 22 8993.4 147.4 100,0% 43.5 8976.0 17.4 5809 139.4 23 8992.7 139.4 100.0% 43.5 8976.0 16.7 5462 131.9 _ 24 8992.1 131.9 100.0% 43.5 8976.0 16.1 5171 124.7 25 8991.5 124.7 100.0% 43.5 8976.0 15.5 4884 118.0 26 8990.9 118.0 100.0% 43.5 8976.0 14.9 4603 111.7 27 8990.3 111.7 100,0% 43.5 8976.0 14.3 4328 105.7 28 8989.8 105.7 100.0% 43.5 8976.0 13.8 4103 100.1 29 8989.3 100.1 100.0% 43.5 8976.0 13.3 3882 94.7 30 8988.8 94.7 100.0% 43.5 8976.0 12.8 3665 89.7 31 8988.3 89.7 100.0% 435 8976.0 12.3 3453 84.9 32 8987.9 84.9 100.0% 43.5 8976.0 11.9 3286 80.4 33 8987.5 80.4 100.0% 43.5 8976.0 11.5 3121 76.1 34 8987.0 76.1 100,0% 43.5 8976.0 11.0 2920 72.1 35 8986.6 72.1 100.0% 43.5 8976.0 10.6 2762 68.2 36 8986.3 68.2 100.0% 43.5 8976.0 10.3 2646 64.6 37 8985.9 64.6 100.0% 43.5 8976.0 9.9 _ 2493 61.2 38 8985.6 61.2 100.0% 43.5 8976.0 9.6 2381 57.9 39 8985.2 57.9 100.0% 43.5 8976.0 9.2 2234 54.8 40 8984.9 54.8 100.0% 43.5 8976.0 8.9 2125 51.9 41 8984.6 51.9 100.0% 43.5 8976,0 8.6 2019 49.1 42 8984.3 49.1 100.0% 43.5 8976.0 8.3 1914 46.5 43 8984.0 46.5 100.0% 43.5 8976.0 8.0 1811 44.0 44 8983.8 44.0 100.0% 43.5 8976.0 7.8 1744 41.6 £.1Projects\W W E1931-004\ 04 0ja uhDa m_Brea c h. x l s Wright Water Engineers, Inc. Des.By: JAW Ckd.By: DMJ 10112/07 dix B Dam Breach Calculations (Page2 of 3) 45 89835 41.6 100.0% 43.5 8876{) 7.5 1644 39.3 46 8983.3 39.3 100.0% 43.5 8878.0 7.3 1579 37.1 47 8983.0 37.1 100.0% 43.5 8978.0 7.0 1482 35.1 48 8882.8 35.1 100.0% 43.5 8970.0 6.8 1419 33.1 49 8982.6 33.1 100.0% 43.5 8976D 6.6 1357 31.3 50 8982.4 31.3 100.0% 43.5 8976.0 6.4 1296 29.5 51 8982.2 29.5 100.0& 43.5 8976.0 6.2 1236 27.8 52 8982.0 27.8 100.0% 43,5 8976.0 6.0 1176 26.2 53 8981.8 26.2 100.0% 43.5 88700 5.8 1118 24.6 54 8881J 24.6 100.0% 43.5 8978J0 5.7 1089 23.1 55 8981.5 23.1 100.896 43.5 8978.0 5.5 1032 21.7 56 8981.3 21.7 100j09k 43.5 89701) 5.3 977 20.4 57 9081.2 20.4 100.0Y6 43.5 8878.0 5.2 949 18D 58 8981D 18.0 100]3Y6 43.5 8978.0 5.0 895 17.8 59 8980.9 17.8 1003% 43.5 8876.0 4.9 868 16.6 60 88807 16.6 100.0% 43.5 8078.0 4.7 816 15.5 61 8980.8 15.5 1000% 43.5 8978.0 4.6 790 14.4 62 8980.5 14.4 100.0Y6 43.5 8978.0 4.5 764 13.4 63 8980.3 13.4 180,0% 43.5 8978.0 4.3 714 12.4 64 8980.2 12.4 100.0% 43.5 8978.0 4.2 689 11.4 65 8980.1 11.4 100.09& 43.5 8978.0 4.1 664 10.5 66 8980.8 10.5 100.0% 43.5 8976.0 4.0 ' 640 9�0 67 8979.9 9.6 100.0% 43.5 8876.0 3.9 616 8.8 68 8978J 8.8 100.0Y4 43.5 8078,0 3.7 570 8.0 69 8079.5 8.0 100.0% 43.5 8870.0 3.5 524 7.3 70 8970.4 7.3 100.0% 43.5 8976D 3.4 502 8.6 71 8979.2 6.6 100.0% 43.5 8976.0 3.2 458 5.9 72 8979.1 5.9 100.0% 43.5 8976.0 3.1 437 5.3 73 8978.8 5.3 100.0% 43.5 88760 2.9 395 4.8 74 8978.8 4.8 100.0% 43.5 8978.0 2.8 375 4.3 75 8978.7 4.3 100.0% 43.5 8978.0 2.7 355 3.8 76 8878.6 3.8 100.0% 43.5 8978-0 2.6 336 3.3 77 8978.5 3.3 108096 43.5 0970.8 2.5 316 2.9 78 8978.4 2.9 100.0Y6 43.5 8970.0 2.4 298 25 79 8978.3 2.5 100DY6 43.5 8976.0 2.3 279 2.1 80 8978.2 2.1 100.096 43.5 8978.0 22 261 1.7 81 8978.2 1.7 100.0Y4 43.5 8978.0 2.2 261 1.4 82 8978.1 1.4 100.0% 43.5 8978.0 2.1 244 1,0 83 8878,0 1.0 100.0% 43.5 8976.0 2.0 226 0.7 84 8977.8 0.7 100.0% 43.5 8978.0 1.8 193 0.5 85 8977.1 0.5 100.0% 43.5 8976.0 1.1 92 0.3 86 8978.8 0i3 100.0% 43.5 8976.0 0i0 57 0.3 87 8076.6 0.3 100i0Y& 43.5 8976.0 0.9 37 0.2 88 8970.5 0.2 100D% 43.5 8976D 0.5 28 0.2 89 8076.4 0.2 100.U°/0 43.5 8876.0 0.4 20 0,1 90 8976.3 0.1 100.0%43.5 8978.0 0.3 13 0.1 ' 91 8976.3 0.1 100.0% 43.5 8978.0 0.3 13 0.1 92 8976.2 0.1 100.0% 43.5 8876.0 0.2 7 0.1 93 89762 0.1 100.0% 43.5 89760 0.2 7 0.1 94 8976.2 0.1 100.0% 43.5 8976.0 0.2 7 0.1 95 89761 0.1 100D% 43.5 8978,0 0.1 3 0.1 96 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 s:Projomv1wWs1931-0041 n+*h,pau,Engineers, Inc. Des.By:*W cx .uxowu Appendix B Dam Breach Calculations (Page3 of 3) 97 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 98 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 99 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 100 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 101 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 102 8976,1 0.1 100.0% 43.5 8976.0 0.1 3 0.1 103 8976.1 0.1 100.0% 43.5 8976.0 0.1 3 0.0 104 8976.1 0.0 100.0% 43.5 8976.0 0.1 3 0.0 105 8976.1 0.0 100.0% 43.5 8976.0 0.1 3 0.0 106 8976.0 0.0 100.0% 43.5 8976.0 0.0 0 0.0 Notes: (1) = Water level elevation corresponding to the storage value in Column (2). Initial water level elev. = 9,000 feet (full reservoir). See Table 1 and Figure 2 for stage -storage relationship. (2) = Column (8) from the previous time step. Initial reservoir volume = 233.4 acre-feet (full reservoir). (3) = Column (3) from Table 2. (4) = Column (6) from Table 2. (5) = Column (4) from Table 2. (6) = Column (1) - Column (5). (7) = the flow out of the breach assuming weir flow: Q = CW LH 3/2 C = 1.84 L = Column (4) H = Column (6) (8) =Column (2) - [Column (7) x 60 seconds] = Initial Conditions = Values from Table 2 = Calculated Value Des.By: JAW EaProjects\WWE1931-064\ Ckd.By: DMJ 040jaw\Dam_Breach.xIs !i'r ihl:r if 'ate!. Engineers. Inc. 10/12/07 w Y = 41'5 0f y N $ ,au J ^' L R 1 LL W m a w 1▪ g O m f B) uaienapg (01 vugenal� (q) u©nenal3 (W} uoiwAal3 m S g g 8 E 212. uommaia • 2 2 2 2 (4) uo.lenoi3 2 tu)14.0wai Si P. 2 2 • 0 0 0 1j) uOileA.aia m aG m m x m m 04) uoila,013 m m 14 (y) uonenat3 8 Y 2 N O 4 ei ap e4 .m ~t0 I) uailenal3 5 8 8 2.a g See (L) uo,10,493 O 0 ta 00.0 0 8 3 2 I (34,3 uoilimajA 03, .[WLimicAeo 14) uougNau (u)..4:mcAeo • a w c a LL LL LLE) 4 r2 171 (iia uNen& (10 uauena13 lul uaplenai3 iul u0I l3 § , a ■ § (\ k`} LL LL (/ ! / I LT § k ) 77- ) \ 7 ¥ 5,7 O. a 411 �i U 141 uoiaxnaa3 k F. tY A r4 9, {10 l/0LW-"U 0 (9 02 (0) u000e.013 2 2 o 11) thmlee,a13 8 0 w 8 8 C•1 2 2 2 2 2 • • 3 3 u0,12,a13 w 121 J 4 Q. a,c [7 N Z. � (j J m O (1} vtNoenei3 DENVER 2490 W. Avenue Suite 100A Denver, Colorado 80211 Phone: 303.480.1700 Fax: 303.480.1020 GLENWOOD SPRINGS 818 Colorado Avenue P.O. Box 219 Glenwood Springs, Colorado 81 602 Phone: 970.945.7755 Fax: 970.945.9210 DURANGO 1666 N. Main Avenue Suite C Durango, Colorado 81301 Phone: 970.259.7411 Fax: 970.259.8758 www.wrightwatencom Wright Water Engineers, Inc ,-•"*Niu • 440011111160„, 07- ; I \PROJECT FILESIMMIECa931-104.040 CAD -GIS LAND SPRINGVALLEYRANCH DWG COMBO.DWG-AL 0 s MEIMICEMENENECCO 1► 500 0 500 100 0 250 = /�/a e ccd Aitcb41::"/151--"tv `1iii! i� Vii--- . „llll�Ir,���� � �/ 6: 1 N Ni5AT1ON AREA UNDEFI�IE Np OROS !"STRUCTURES '\ WRIGHT WATER ENGINEERS, INC. 818 Colorado Avenue, Suite 307 GLENWOOD SPRINGS, CO 81601 (970)945-7755 FAX(970)945-9210 %N0. BY DATE In REVISIONS DESCRIPTION COMMENTS DATE DESIGN JAW/DKW 10/12/07 DETAIL CHECK APPROVAL DKW TAE 10/12/07 10/12/07 SCALE FILE Combo.dwg 1"=500' Spring Valley Ranch P. U.D. Map 1 Hopkins Dam Breach Inundation Area JOB N0. 931-004.040 REVISION N0. 0 s SHEET N0. 1