F.l ENE RCON CALCULATION COVER SHEETF. ::I ENE R C 0 N Calculation Design Verification Plan:...

TXUT -00 1-FSAR-2.4.3-CALC-011

F.l ENE RCON CALCULATION COVER SHEET REV. 4 PAGE NO. 1 of36

Probable Maximum Precipitation Calculation for Comanche Client: MNES

Title: Peak Nuclear Power Plant Units 3 and 4 using HMR 51 & HMR Project: MITS116 - Luminant 52. COLA

Item Cover Sheet Items Yes No

1 Does this calculation contain any open assumptions that require confirmation?

X (If YES, identify the assumptions)

Does this calculation serve as an "Alternate Calculation"? (If YES, identify the

2 design verified calculation.) X Design Verified Calculation No.

Does this calculation supersede an existing calculation? (If YES, identify the

3 superseded calculation.) X Superseded Calculation No.

Scope of Revision: The calculation was revised to address the issues described in the Corrective Action Report (CAR) Number TXUT001-CAR-31. The revisions include: basin areas, parameters obtained from hydrometeorological reports (HMR) charts, basin area coordinates, and other minor discrepancies. Some minor editorial changes have also been addressed.

Revision Impact on Results: The runoff estimate using HEC-HMS at the junction of Paluxy River and Squaw Creek increased due to the revision. The runoff for the Squaw Creek Reservoir has also increased. The critical storm centers for both Overall Watershed and Squaw Creek Reservoir Watershed have changed.

Study Calculation 0 Final Calculation IZI

Safety-Related rzl Non-safety-Related 0

(Print Name and Sign)

Originator: Lana Lawrence 4~N r- Date: ~/26'/q:J/.3 Design Verifier: John Huggins ........... ~ t .\:.,{.__..,...,_ .... - Date: 2/26/2013 -. -;. 1 t -Approver: Pat Brunette ~/c;/(!}5~~ Date: ;;/z~/'LDI:S

,ji ENE R CON

REVISION

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4

PAGE REVISION STATUS

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APPENDIX REVISION STATUS

CALCULATION

REVISION STATUS SHEET

CALCULATION REVISION STATUS

REVISION

4

DATE

August04,2008

August 14, 2009

June 24, 2010

December 10, 2010

February 26, 2013

PAGE NO.

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DESCRIPTION

Original Calculation

Revision 1 - The revised calculation accounts for updated Snyder's unit hydrograph coefficients.

Included PMP computation within the Squaw Creek Reservoir watershed (Basin 1 only) and also utilized revised HEC-HMS Model from Calc. 012.

Revised to utilize HEC-HMS Model from Calc. 012, Rev 3.

Basin areas and coordinates changed, input parameters from HMR 51 and 52 charts changed.

REVISION

APPENDIX NO. PAGE NO. REVISION NO. APPENDIX NO. PAGE NO. REVISION NO.

A

B

1-610

1-25

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F. ::I ENE R C 0 N

Calculation Design Verification Plan:

CALCULATION

DESIGN VERIFICATION PLAN

AND SUMMARY SHEET

Apply CSP Number 3.01 , Revision 6, Section 4.5a. to include at a minimum:

TXUT -001-FSAR-2.4.3-CALC-011

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1 . Review the changes to Revision 4 and make a determination as to whether the calculation of the PMP is based on sound theory.

2. Examine the methodology and assumptions to ensure they are applied correctly and are accurate for the PMP calculation.

(Print Name and Sign for Approval- mark liN/A" if not required)

Approver: Pat Brunette 0~0~~) Date: :;z/::l..t? lzot3 Calculation Design Verification Summary:

I have reviewed the Comanche Peak PMP calculation to Revision 4 and have concluded that:

1. The methodology, assumptions and inputs for Revision 4 are reasonable and in accordance with CSP Number 3.01, Revision 6.

2. The methodology, assumptions and inputs are appropriate and have been applied correctly.

3. The calculation provides a reasonable estimate of the PMP and the output and results were verified.

4. The Originator has addressed all pertinent comments given during the review process to my satisfaction.

Based on the above summary, the calculation is determined to be acceptable.

(Print Name and Sign)

Design Verifier: John Huggins Date: 2/26/2013

Others: II/A Date: t{/)

TXUT -001-FSAR-2.4.3-CALCULATION CALC-011

F.::J E N E R C 0 N DESIGN VERIFICATION REV. 4 CHECKLIST

PAGE NO. 4of36

Item Cover Sheet Items Yes No N/A

Design Inputs- Were the design inputs correctly selected, referenced (latest

X 1 revision), consistent with the design basis and incorporated in the calculation? 2

Assumptions - Were the assumptions reasonable and adequately X described, justified and/or verified, and documented? 3

Quality Assurance - Were the appropriate QA classification and X requirements assigned to the calculation? Codes, Standard and Regulatory Requirements - Were the applicable

X 4 codes, standards and regulatory requirements, including issue and addenda, properly identified and their requirements satisfied? 5

Construction and Operating Experience- Have applicable construction and X operating experience been considered? 6

Interfaces - Have the design interface requirements been satisfied, X including interactions with other calculations? 7

Methods - Was the calculation methodology appropriate and properly X applied to satisfy the calculation objective? Design Outputs - Was the conclusion of the calculation clearly stated, did it

X 8 correspond directly with the objectives and are the results reasonable compared to the inputs? 9

Radiation Exposure - Has the calculation properly considered radiation X exposure to the public and plant personnel? Acceptance Criteria - Are the acceptance criteria incorporated in the

X 10 calculation sufficient to allow verification that the design requirements have been satisfactorily accomplished?

11 Computer Software -Is a computer program or software used, and if so, are X the requirements of CSP 3.02 met?

COMMENTS:

(Print Name and Sign) . Design Verifier: John Huggins doL t U. ... r.t.~ Date: 2/26/2013 11 l I . Others: KIA Date: N'/A

CALCULATION CONTROL SHEET

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Table of Contents

Table of Contents .......................................................................................................................................... 5

1.0 Purpose and Scope ............................................................................................................................. 8

2.0 Summary of Results and Conclusion .................................................................................................. 8

3.0 References .......................................................................................................................................... 9

4.0 Assumptions ...................................................................................................................................... 10

5.0 Design Inputs .................................................................................................................................... 10

6.0 Methodology ...................................................................................................................................... 11

7.0 Calculations ....................................................................................................................................... 12

8.0 Appendices ........................................................................................................................................ 36



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List of Tables

Table 2-1. 6-Hour Incremental PMP Estimates ........................................................................................... 8 Table 7-1. Watershed Drainage Areas ....................................................................................................... 13 Table 7-2. Depth Area Duration PMP Values ............................................................................................. 15 Table 7-3. Basin 1 Drainage Basin Coordinates ......................................................................................... 16 Table 7-4. Basin 2 Drainage Basin Coordinates ......................................................................................... 17 Table 7-5. Basin 3 Drainage Basin Coordinates ......................................................................................... 17 Table 7-6. Basin 4 Drainage Basin Coordinates ......................................................................................... 18 Table 7-7. Overall Watershed Drainage Basin Coordinates ....................................................................... 19 Table 7-8. Coordinates of Trial Storm Centers ........................................................................................... 20 Table 7-9. Critical Storm Center Determination .......................................................................................... 21 Table 7-10. Rainfall-Runoff Analysis for Overall Watershed Using HEC-HMS and Overall PMP with Four

Temporal Distributions at the Critical Storm Center PR 10 ..................................................... 22 Table 7-11. Rainfall-Runoff Analysis for Squaw Creek Reservoir Watershed (Basin 1) Using HEC-HMS

and Basin 1 Only PMP with Four Temporal Distributions at the Critical Storm Center SC 4 . 22 Table 7-12. Basin 1 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), HMR 52 Temporal

Distribution ............................................................................................................................... 24 Table 7-13. Basin 2 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), HMR 52 Temporal



Distribution ............................................................................................................................... 27 Table 7-16. Basin 1 Hourly PMP – Basin 1 Only PMP, Critical Storm Center (SC 4), HMR 52 Temporal

Distribution ............................................................................................................................... 28 Table 7-17. Basin 1 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), Critical Temporal

Distribution (Two-Thirds) ......................................................................................................... 29 Table 7-18. Basin 2 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), Critical Temporal



Distribution (Two-Thirds) ......................................................................................................... 32 Table 7-21. Basin 1 Hourly PMP – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal

Distribution (Two-Thirds) ......................................................................................................... 35



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List of Figures

Figure 7-1. Drainage Basin Map with Storm Centers ................................................................................. 13 Figure 7-2. All-Season PMP (inch) for 6 hr. 10 sq. mi Basin ...................................................................... 14 Figure 7-3. Drainage Basin Map with Storm Centers for HMR 52 Input ..................................................... 15 Figure 7-4. Basin 1 Hyetograph - Overall PMP, Critical Storm Center (PR 10), Critical Temporal

Distribution (Two-Thirds) ......................................................................................................... 29 Figure 7-5. Basin 2 Hyetograph - Overall PMP, Critical Storm Center (PR 10), Critical Temporal



Distribution (Two-Thirds) ......................................................................................................... 32 Figure 7-8. Basin 1 Mass Curve - Overall PMP, Critical Storm Center (PR 10), Critical Temporal




Distribution (Two-Thirds) ......................................................................................................... 34 Figure 7-12. Basin 1 Hyetograph – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal

Distribution (Two-Thirds) ......................................................................................................... 35 Figure 7-13. Basin 1 Mass Curve – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal

Distribution (Two-Thirds) ......................................................................................................... 36



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1.0 Purpose and Scope

The purpose of this calculation is to determine the 72-hour Probable Maximum Precipitation (PMP) distributions using Hydrometeorological Report (HMR) 51 (Reference 2) and HMR 52 (Reference 3) for the Comanche Peak Nuclear Power Plant (CPNPP) Units 3 and 4. The PMP distributions are used as input to determine the Probable Maximum Flood (PMF).

2.0 Summary of Results and Conclusions

The PMP distributions are calculated for the following scenarios: Overall PMP for storm centers within the Squaw Creek watershed Overall PMP for storm centers within the Paluxy River watershed Squaw Creek Reservoir PMP for storm centers within the Squaw Creek watershed

The Squaw Creek and Paluxy River watersheds are shown in Figure 7-1. The critical storm center within the Paluxy River watershed (Basin 4) results in the maximum PMP for the overall watershed (Basins 1, 2, 3 and 4 combined) at the confluence of Paluxy River and Squaw Creek. When the storm center was kept in the Squaw Creek watershed (Basins 1 and 2), it resulted in a higher PMP for the Squaw Creek watershed. A higher PMP for the Squaw Creek watershed can result in a higher water surface elevation at CPNPP Units 3 and 4. Also, a smaller watershed area results in more intense precipitation. Therefore, an additional PMP was determined for Basin 1 only as a separate watershed. This is a conservative approach because two different PMPs are applied to the subbasins within the same overall watershed (Overall Watershed for Paluxy River and Squaw Creek junction right before they join the Brazos River). The PMPs for the above mentioned scenarios were analyzed individually to determine the resulting peak runoff.

Table 2-1 summarizes the 6-hour incremental PMP estimates in inches (in.). The PMP estimates for different trial centers are presented in Section 7.0, Table 7-9

Table 2-1. 6-Hour Incremental PMP Estimates

6-hour increment

(hour from 0)

Overall PMP(in.)

Squaw Creek Reservoir PMP (Basin 1 Only)

(in.) 6 0.60 0.59 12 0.72 0.72 18 0.92 0.92 24 1.26 1.27 30 1.99 2.05 36 4.80 5.58 42 18.05 25.01 48 2.82 2.98 54 1.54 1.56 60 1.06 1.06 66 0.81 0.80 72 0.66 0.65

Total 35.22 43.19



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The storm rainfall total for the Overall PMP is 35.22 in. for a 450 square mile (sq. mi.) storm, centered near the overall watershed centroid with an orientation of 295 degrees. The storm rainfall total for the Squaw Creek Reservoir PMP (Basin 1 Only) is 43.19 in. for a 50 sq. mi. storm, centered near the Squaw Creek watershed centroid with an orientation of 301 degrees. The critical storm centers for the Paluxy River and the Squaw Creek are indicated as PR 10 and SC 4, respectively, as shown in Figure 7-1. The two-thirds peaking temporal distribution with the storm center at PR 10 is the critical distribution for the Paluxy River and Squaw Creek combined watershed. The two-thirds peaking temporal distribution with the storm center at SC 4 is the critical distribution for the Squaw Creek Reservoir watershed.

Compared to the Revision 3 of this calculation, the runoff estimate at the junction of Paluxy River and Squaw Creek has increased. The runoff for the Squaw Creek Reservoir has also increased. However, the increases are not significant – approximately 5% runoff increase at the junction of Paluxy River and Squaw Creek and approximately 8% runoff increase for the Squaw Creek Reservoir. These increases are not expected to affect significantly the resulting water surface elevations.

3.0 References

1. Autodesk, AutoCAD Civil 3D 2012 SP1, Version F.107.0.0 software.

2. National Oceanic and Atmospheric Administration, “Hydrometeorological Report No. 51, Probable Maximum Precipitation Estimates, United States East of the 105th Meridian,” Prepared by Louis C. Scheriner and John T. Riedel, Hydrometeorological Branch, Office of Hydrology, National Weather Services, Washington D.C. 1978, Reprinted August 1980.

3. National Oceanic and Atmospheric Administration, National Weather Service, Hydrometeorological Report No. 52, Application of Probable Maximum Precipitation Estimates – United States East of the 105th Meridian, August 1982.

4. U.S. Army Corps of Engineers, Hydrologic Engineering Center, Generalized Computer Program, HMR 52, Probable Maximum Storm (Eastern United States), User’s Manual, CPD-46, Revised April 1987.

5. U.S. Army Corps of Engineers, Hydrologic Engineering Center, Generalized Computer Program, HMR 52, Probable Maximum Storm, Revised April 1991.

6. U.S. Army Corps of Engineers, Hydrologic Engineering Center, Hydrologic Modeling System, HEC-HMS computer software, version 3.5.

7. U.S. Geological Survey, Geospatial Data Gateway Website, http://datagateway.nrcs.usda.gov/,accessed December 27, 2007.

8. ESRI ArcGIS Desktop 10 Computer Software.

9. Enercon Calculation, “TXUT-001-FSAR-2.4.3-CALC-012, Rev.5 MITS004 – Probable Maximum Flood Calculation for Comanche Peak Nuclear Power Plant Units 3 and 4 (HEC-HMS & HEC-RAS).”

10. Squaw Creek Dam TX04627 Breach Analysis, April 2008, Prepared for TXU by Freese and Nichols Inc.



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11. U.S. Nuclear Regulatory Commission, “Design Basis Floods for Nuclear Power Plants,” Regulatory Guide 1.59, August 1977.

12. American Nuclear Society, “American National Standard for Determining Design Basis Flooding at Power Reactor Sites,” ANSI/ANS-2.8-1992, American Nuclear Society, La Grange Park, Illinois, July 28, 1992.

13. U.S. Nuclear Regulatory Commission, “Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants,” Regulatory Guide 1.70, November 1978.

14. U.S. Nuclear Regulatory Commission, “Flood Protection for Nuclear Power Plants,” Regulatory Guide 1.102, September 1976.

15. U.S. Nuclear Regulatory Commission, “Combined License Applications for Nuclear Power Plants,” Regulatory Guide 1.206, June 2007.

16. U.S. Nuclear Regulatory Commission, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants,” NUREG-0800, May 2007.

17. U.S. Nuclear Regulatory Commission, “Early Site Permits; Standard design Certifications; and Combined Licenses for Nuclear Power Plants,” 10 CFR Part 52, August 2007.

18. U.S. Nuclear Regulatory Commission, “Industry Guidelines for Combined License Applicants under 10 CFR Part 52,” NEI 04-05, October 2005.

19. Texas Utilities Services Inc., Comanche Peak Stream Electric Station CPSES 1980-1982, Units 1 and 2, “Safe Shutdown Impoundment Dam, Design Calculations and Calculations Check,” Volume 1, by Freese and Nichols.

20. Texas Utilities Services Inc., Comanche Peak Stream Electric Station CPSES 1980-1982, Units 1 and 2, “Safe Shutdown Impoundment Dam, Design Calculations and Calculations Check,” Volume 2, by Freese and Nichols.

21. National Oceanic and Atmospheric Administration’s National Weather Service Website, http://www.nws.noaa.gov/oh/hdsc/studies/pmp.html , accessed December 2012.

22. U.S. Nuclear Regulatory Commission, “Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the United States of America,” Regulatory Guide NUREG/CR-7046, November 2011.

4.0 Assumptions

None.

5.0 Design Inputs

Drainage basin location is the input needed for HMR 51. The CPNPP Units 3 and 4 locations from the USGS Hill City, TX Quadrangle NAD83 (Reference 7) are as follows: 32° 18’ 10” N 97° 47’ 30” W



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Input to the HMR 52 software includes the coordinates defining the drainage basins shown in Figure 7-1.

HMR 51 (Reference 2) resulted in all-season PMP estimates, which are then used as input for the HMR 52. The basin and sub-basin geometry, preferred storm orientation, HMR 51 PMP estimates, storm center, and isohyet A ratio were included as input data into the HMR 52 software.

6.0 Methodology

Reference to and compliance with the following listed design guides were considered in evaluating the PMP for CPNPP Units 3 and 4 using HMR 51 & HMR 52. All other procedures, instructions and design guides listed in Section 5.4 of Project Planning Document (PPD No. TXUT-001, Rev. 3) are not specifically applicable in evaluating the PMP.

U.S. Nuclear Regulatory Commission, “Standard Review Plan,” NUREG-0800, March 2007, (Reference 16).

U.S. Nuclear Regulatory Commission, “Design Basis Floods for Nuclear Power Plants, Alternative Methods of Estimating Probable Maximum Floods,” Regulatory Guide 1.59, August 1977, (Reference 11).

American Nuclear Society, “Determining Design Basis Flooding at Power Reactor Sites,” ANSI/ANS-2.8-1992, July 28, 1992, (Reference 12).

U.S. Nuclear Regulatory Commission, “Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants,” Regulatory Guide 1.70, November 1978, (Reference 13).

U.S. Nuclear Regulatory Commission, “Flood Protection for Nuclear Power Plants,” Regulatory Guide 1.102, September 1976, (Reference 14).

U.S. Nuclear Regulatory Commission, “Combined License Applications for Nuclear Power Plants (LWR Edition),” Regulatory Guide 1.206, June 2007, (Reference 15).

U.S. Nuclear Regulatory Commission, “Early Site Permits; Standard design Certifications; and Combined Licenses for Nuclear Power Plants,” 10 CFR Part 52, August 2007 (Reference 17).

U.S. Nuclear Regulatory Commission, “Industry Guidelines for Combined License Applicants under 10 CFR Part 52,” NEI 04-05, October 2005, (Reference 18).

The Regulatory Guide 1.59 (Reference 11) and NUREG/CR-7046 (Reference 22) indicate use of ANSI N170-1976 "Standards for Determining Design Basis Flooding at Power Reactor Sites," (Reference 12). ANSI/ANS-2.8-1992 was issued to supersede ANSI N170-1976. Although ANSI/ANS-2.8-1992 has been withdrawn, a replacement standard has not been issued by the American Nuclear Society as of January 2013. The NRC NUREG-0800, March 2007 (Reference 16), includes ANSI/ANS-2.8-1992 as a historical technical reference.

HMR 52 applies to areas in the United States east of the 105th Meridian. The HMR 52 software iterates to achieve the optimal storm area size that maximizes precipitation. The resulting storm area size may differ from the actual drainage area of the basin. The HMR 52 software also iterates to achieve the optimal storm orientation that maximizes precipitation. As identified by HMR 52 guidance (Reference 3), when the optimal storm orientation differs from the preferred storm orientation by more than 40 degrees, a reduction to the precipitation should be made. This reduction occurs automatically within the HMR 52 software.

An antecedent storm equal to 40 percent of the PMP precedes the PMP storm with a 3-day dry period between the storms, as described in Nuclear Regulatory Commission (NRC) Regulatory Guide 1.59



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(Reference 11), ANSI/ANS-2.8-1992 (Reference 12), and NUREG/CR-7046 (Reference 22), and was considered for the PMF analysis. HMR 52 guidance provides a stepwise approach to determine spatial and temporal distribution of the all-season PMP estimates derived from HMR 51 for incremental durations less than or equal to 6 hours (hr.). HMR 52 provides a recommended elliptical isohyetal pattern (Reference 3, Figure 5) to be used. The critical PMP storm was determined through several iterations of storm center locations within Squaw Creek and Paluxy River watersheds. In addition, HMR 52 recommends a temporal distribution that includes arranging the individual 6-hour increments such that they decrease progressively to either side of the greatest 6-hr. increment. Furthermore, the four greatest 6-hr. increments should be placed at any position except within the first 24-hr. period. The temporal distributions used herein are explained in Section 7.0

Complete descriptions of the HMR 52 process and the HMR 52 software are provided in the HMR 52 guidance (Reference 3) and HMR 52 software user’s manual (Reference 4).

HEC-HMS 3.5, HMR 52, AutoCAD Civil 3D 2012 SP1 Version F.107.0.0 and ESRI ArcGIS Desktop 10 software have been certified in accordance with Enercon Corporate Standard Procedure (CSP) 3.02, Revision 5. The software certification documents are maintained by Enercon as part of the Quality Assurance program.

7.0 Calculations

Scenarios

The CPNPP Units 3 and 4 are located just upstream of Squaw Creek Dam, which is located upstream of the confluence of Squaw Creek and Paluxy River shown in Figure 7-1. Therefore, the critical PMP resulting in the PMF for the site may be one of the following:

Overall PMP with critical storm center within the Squaw Creek watershed Overall PMP with critical storm center within the Paluxy River watershed Squaw Creek Reservoir PMP with critical storm center within the Squaw Creek watershed

Drainage Areas

The CPNPP Units 3 and 4 are located within the Squaw Creek watershed. Squaw Creek is a tributary of the Paluxy River, and in turn the Paluxy River is a tributary of the Brazos River.

The Squaw Creek and Paluxy River watersheds are divided into four basins, as shown in Figure 7-1. Basins 1 and 2 represent the Squaw Creek watershed, and Basins 3 and 4 represent the Paluxy River watershed. The area upstream of the Squaw Creek Reservoir is steeper and has different basin properties compared to the area around and within the Squaw Creek Reservoir. Due to the variation of slope, Basin 1 has been further subdivided into three sub-basins 1a, 1b and 1c. Basin 1a represents the drainage area above Squaw Creek Reservoir, Basin 1b represents the contributing area adjacent to Squaw Creek Reservoir, and Basin 1c represents Squaw Creek Reservoir. Basin 2 represents the Squaw Creek watershed downstream of the dam to the confluence of the Paluxy River. Basin 3 represents the Paluxy River watershed from the confluence of Squaw Creek to the city of Glen Rose. Basin 4 represents the drainage area north of Glen Rose. The general drainage pattern is to the southeast and ultimately drains into the Brazos River.

The drainage areas were delineated and measured using ArcGIS (Reference 8) based on the United States Geological Survey’s (USGS) topographical maps. The USGS topographical maps were obtained from the USDA’s Geospatial Data Gateway (Reference 7). The determined watershed areas



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Creek watershed was also similar to that used in Texas Utilities Services Inc., Comanche Peak Steam Electric Station Units 1 and 2 CPSES SSI Dam Design Calculation and Calculation Check, Volume 1 and 2 (Reference 19 and Reference 20), hereafter referred as the SSI Dam Design Calculation. Figure 7-1 illustrates the watershed sub-basins and boundaries. The drainage areas are shown in Table 7-1.

Figure 7-1. Drainage Basin Map with Storm Centers

Table 7-1. Watershed Drainage Areas

Watershed Drainage Area (sq. mi.) Basin 1a 37.81 Basin 1b 21.50 Basin 1c 4.95

Basin 1 Total 64.26

- Critical Storm Centers



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Basin 2 10.72 Basin 3 24.31 Basin 4 410.52

PMP Estimates – HMR 51 and HMR 52

HMR 51 applies to areas in the United States east of the 105th Meridian. The all-season PMP estimates for drainage areas from 10 to 20,000 sq. mi. for durations from 6 to 72 hours are obtained using HMR 51 PMP charts (Reference 2, Figures 18-47) and are shown in Table 7-2. Digitized maps of the HMR 51 PMP charts are available from National Oceanic and Atmospheric Administration (NOAA) National Weather Service website (Reference 21). The digitized maps are imported in AutoCAD along with the watershed boundary shown in Figure 7-1 to determine the PMP estimates in Table 7-2; linear interpolation between the PMP curves was used. An example of a PMP estimate employing Reference 2, Figure 18 with a basin area of 10 sq. mi. and for duration of 6 hours is shown in Figure 7-2.

Figure 7-2. All-Season PMP (inch) for 6 hr. 10 sq. mi Basin (Reference 2, Figure 18)

CPNPP



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Table 7-2. Depth Area Duration PMP Values (inches) duration (hr.) 6 12 24 48 72 10 29.83 36.09 41.33 46.33 49.01

area 200 22.33 27.19 32.65 36.76 40.45sq. mi. 1000 16.19 21.18 26.21 30.62 33.88

5000 9.35 13.05 17.90 22.39 25.42 10000 7.11 10.35 14.58 18.67 21.76 20000 5.20 8.23 11.64 15.27 18.11

As mentioned above, USGS topographic maps were obtained from the USDA’s Geospatial Data Gateway (Reference 7), and the drainage basin boundaries were mapped using ArcGIS software (Reference 8). The drainage area boundaries were simplified using AutoCAD (Reference 1) to satisfy the HMR 52 requirement of having maximum of 100 basin coordinates. The actual drainage areas and simplified basin areas match up to three significant digits (in square miles). The simplified basin boundaries and actual drainage area boundaries are shown in Figure 7-3.

Figure 7-3. Drainage Basin Map with Storm Centers for HMR 52 Input



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A user coordinate system was used in AutoCAD to describe the coordinates of the basins in order to reduce the coordinate’s number of digits to satisfy the HMR 52 requirements. Change of the coordinate system only affects the location of the 0,0 coordinate and does not affect the scale or orientation of the drawing. Coordinates are read in feet and converted into miles (1 mile = 5280 feet). Basins X, Y coordinates are shown in Tables 7-3 through 7-7. The coordinates are provided in clockwise order. The coordinates of the storm centers are provided in Table 7-8. The CPNPP Units 3 and 4 location as described in Section 5.0 corresponds to X, Y coordinate of 13.471 miles (mi.) and 8.122 mi. respectively in AutoCAD (Reference 1).

Table 7-3. Basin 1 Drainage Basin Coordinates

No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) 1 18.958 21.897 27 29.634 11.732 2 19.759 21.713 28 29.527 11.743 3 20.895 20.536 29 29.431 11.604 4 21.958 21.245 30 29.136 11.669 5 22.767 20.921 31 28.728 12.065 6 23.302 21.017 32 27.601 12.263 7 23.939 20.342 33 27.130 12.684 8 24.553 20.381 34 26.697 12.721 9 25.676 19.859 35 26.251 13.749 10 26.500 19.081 36 26.177 14.158 11 27.709 19.059 37 25.517 14.512 12 28.719 18.695 38 25.040 14.654 13 29.261 17.199 39 24.319 15.061 14 29.784 17.321 40 23.552 14.901 15 30.116 16.995 41 23.197 14.995 16 30.430 17.300 42 23.040 15.427 17 31.870 16.325 43 22.326 15.792 18 32.330 14.535 44 21.785 17.109 19 31.812 13.442 45 20.876 17.692 20 31.110 12.663 46 20.332 18.479 21 30.640 12.235 47 19.358 19.580 22 30.533 11.764 48 19.243 20.213 23 30.330 11.646 49 19.018 20.238 24 30.169 11.721 50 18.857 21.088 25 30.051 11.518 51 19.038 21.542 26 29.880 11.497



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No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) 1 32.330 14.535 10 32.264 10.427 2 34.048 12.583 11 31.687 10.855 3 34.871 11.920 12 31.045 11.293 4 34.864 11.154 13 30.906 11.368 5 34.200 11.015 14 30.713 11.636 6 33.783 10.534 15 30.533 11.764 7 33.690 9.693 16 30.640 12.235 8 32.981 9.732 17 31.110 12.663 9 32.542 10.341 18 31.812 13.442


No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) 1 33.690 9.693 24 29.629 7.289 2 33.415 9.028 25 29.966 8.078 3 33.490 7.691 26 30.337 8.598 4 33.098 7.689 27 30.484 9.454 5 32.565 6.853 28 30.152 9.942 6 32.518 6.230 29 29.497 10.629 7 32.036 5.871 30 29.136 11.669 8 32.034 4.504 31 29.431 11.604 9 31.692 3.975 32 29.527 11.743 10 31.853 3.006 33 29.634 11.732 11 31.362 2.091 34 29.880 11.497 12 31.156 2.021 35 30.051 11.518 13 30.846 2.280 36 30.169 11.721 14 30.157 2.169 37 30.330 11.646 15 29.303 2.601 38 30.533 11.764 16 29.481 2.884 39 30.713 11.636 17 29.449 3.369 40 30.906 11.368 18 29.529 4.026 41 31.045 11.293 19 29.820 4.118 42 31.687 10.855 20 29.730 4.491 43 32.264 10.427 21 30.058 5.699 44 32.542 10.341 22 29.723 6.472 45 32.981 9.732 23 29.427 7.100



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No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) 1 0.000 17.600 35 26.697 12.721 69 23.056 3.447 2 0.875 19.632 36 27.130 12.684 70 22.685 3.038 3 2.006 20.782 37 27.601 12.263 71 22.066 2.728 4 2.586 20.809 38 28.728 12.065 72 21.013 1.317 5 3.624 21.938 39 29.136 11.669 73 20.654 1.664 6 3.296 22.739 40 29.497 10.629 74 19.240 0.000 7 3.393 22.950 41 30.152 9.942 75 18.684 0.414 8 5.142 22.475 42 30.484 9.454 76 18.689 0.888 9 6.803 24.548 43 30.337 8.598 77 18.041 1.478 10 9.325 23.897 44 29.966 8.078 78 18.266 2.095 11 11.726 23.952 45 29.629 7.289 79 17.422 2.815 12 14.501 23.692 46 29.427 7.100 80 16.828 2.555 13 14.701 24.089 47 29.723 6.472 81 16.172 2.759 14 16.320 23.594 48 30.058 5.699 82 15.391 3.569 15 16.873 22.620 49 29.730 4.491 83 14.965 4.746 16 17.542 22.825 50 29.820 4.118 84 12.977 5.180 17 18.958 21.897 51 29.529 4.026 85 11.047 5.340 18 19.038 21.542 52 29.449 3.369 86 9.819 7.149 19 18.857 21.088 53 29.481 2.884 87 8.965 7.768 20 19.018 20.238 54 29.303 2.601 88 9.207 8.273 21 19.243 20.213 55 28.901 2.540 89 8.792 8.821 22 19.358 19.580 56 28.331 1.725 90 8.892 9.635 23 20.332 18.479 57 27.752 1.715 91 7.467 9.960 24 20.876 17.692 58 27.301 2.028 92 7.629 10.581 25 21.785 17.109 59 26.474 1.722 93 6.879 11.143 26 22.326 15.792 60 26.370 1.975 94 5.951 10.838 27 23.040 15.427 61 25.979 2.122 95 5.461 11.842 28 23.197 14.995 62 26.103 2.307 96 4.866 12.164 29 23.552 14.901 63 25.063 3.728 97 4.496 13.595 30 24.319 15.061 64 24.505 3.731 98 2.464 14.652 31 25.040 14.654 65 23.897 4.688 99 2.379 15.326 32 25.517 14.512 66 23.574 4.219 100 0.817 16.102 33 26.177 14.158 67 22.799 4.348 34 26.251 13.749 68 22.722 3.942



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Table 7-7. Overall Watershed Drainage Basin Coordinates

No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) 1 0.000 17.600 35 34.048 12.583 69 23.056 3.447 2 0.875 19.632 36 34.871 11.920 70 22.685 3.038 3 2.006 20.782 37 34.864 11.154 71 22.066 2.728 4 2.586 20.809 38 34.200 11.015 72 21.013 1.317 5 3.624 21.938 39 33.783 10.534 73 20.654 1.664 6 3.296 22.739 40 33.690 9.693 74 19.240 0.000 7 3.393 22.950 41 33.415 9.028 75 18.684 0.414 8 5.142 22.475 42 33.490 7.691 76 18.689 0.888 9 6.803 24.548 43 33.098 7.689 77 18.041 1.478 10 9.325 23.897 44 32.565 6.853 78 18.266 2.095 11 11.726 23.952 45 32.518 6.230 79 17.422 2.815 12 14.501 23.692 46 32.036 5.871 80 16.828 2.555 13 14.701 24.089 47 32.034 4.504 81 16.172 2.759 14 16.320 23.594 48 31.692 3.975 82 15.391 3.569 15 16.873 22.620 49 31.853 3.006 83 14.965 4.746 16 17.542 22.825 50 31.362 2.091 84 12.977 5.180 17 18.958 21.897 51 31.156 2.021 85 11.047 5.340 18 19.759 21.713 52 30.846 2.280 86 9.819 7.149 19 20.895 20.536 53 30.157 2.169 87 8.965 7.768 20 21.958 21.245 54 29.303 2.601 88 9.207 8.273 21 22.767 20.921 55 28.901 2.540 89 8.792 8.821 22 23.302 21.017 56 28.331 1.725 90 8.892 9.635 23 23.939 20.342 57 27.752 1.715 91 7.467 9.960 24 24.553 20.381 58 27.301 2.028 92 7.629 10.581 25 25.676 19.859 59 26.474 1.722 93 6.879 11.143 26 26.500 19.081 60 26.370 1.975 94 5.951 10.838 27 27.709 19.059 61 25.979 2.122 95 5.461 11.842 28 28.719 18.695 62 26.103 2.307 96 4.866 12.164 29 29.261 17.199 63 25.063 3.728 97 4.496 13.595 30 29.784 17.321 64 24.505 3.731 98 2.464 14.652 31 30.116 16.995 65 23.897 4.688 99 2.379 15.326 32 30.430 17.300 66 23.574 4.219 100 0.817 16.102 33 31.870 16.325 67 22.799 4.348 34 32.330 14.535 68 22.722 3.942



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Table 7-8. Coordinates of Trial Storm Centers

No. X (mi.) Y (mi.) No. X (mi.) Y (mi.) PR 1 1.298 19.956 SC 1 30.467 12.852 PR 2 13.471 8.122 SC 2 24.725 15.332 PR 3 14.547 10.765 SC 3 24.790 15.919 PR 4 15.721 13.505 SC 4 25.378 16.832 PR 5 16.994 16.343 SC 5 26.291 18.007 PR 6 18.299 18.790 SC 6 24.725 17.420 PR 7 20.876 17.224 SC 7 19.212 21.595 PR 8 19.408 14.908 SC 8 33.268 11.955 PR 9 22.181 13.570 SC 9 26.944 16.017 PR 10 20.974 11.287 PR 11 30.467 8.514 PR 12 18.364 12.494

HMR 52 (Reference 3, Figure 8) was used to determine the preferred orientation of 216 degrees for the storm based on the location of CPNPP Units 3 and 4. HMR 52 (Reference 5) software iterates to achieve the optimal storm orientation that maximizes precipitation. As identified by HMR 52 guidance (Reference 3), when the optimal storm orientation differs from the preferred storm orientation by more than 40 degrees, a reduction to the precipitation should be made. This reduction occurs automatically within the HMR 52 software. HMR 52 (Reference 3, Figure 39) was used to determine the 1-hr. to 6-hr. precipitation ratio of 0.304 for isohyet A of a 20,000 sq.mi. based on the location of CPNPP Units 3 and 4.

Determining the critical storm center is an iterative process of computing the hourly PMP and rainfall runoff for several storm centers. The storm center resulting in the highest precipitation might not be the same storm center that results in the largest runoff. The PMP obtained for each storm center is analyzed to calculate the runoff using HEC-HMS (Reference 6). The HEC-HMS model and inputs are described in detail within a separate Enercon Calculation entitled “TXUT-001-FSAR-2.4.3-CALC-012, MITS004 – Probable Maximum Flood Calculation for Comanche Peak Nuclear Power Plant Units 3 and 4 (HEC-HMS & HEC-RAS)” (Reference 9), hereafter referred to as the Enercon PMF Calculation. The summary results, the precipitation and runoff, for each storm center are presented in Table 7-9.



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Table 7-9. Critical Storm Center Determination

Overall Watershed PMP Squaw Creek Reservoir PMP (Basin 1 Only)

Overall PMP for Watershed Overall PMP for Basin 1 Basin 1 Only PMP

StormCenter

HMR 52 PMP

estimates(Watershed

)

Runoff estimates from HEC-HMS

(at junction Paluxy Rvr & Squaw Cr)

StormCenter

HMR 52 PMP

estimates(Basin 1)

Runoff estimates from HEC-HMS (Inflow to Squaw

Cr. Reservoir)

StormCenter

HMR 52 PMP

estimates(Basin 1)

Runoffestimates from

HEC-HMS(Inflow to

Squaw Cr. Reservoir)

(in) (cfs) (in) (cfs) (in) (cfs) SC 1 32.665 870,763 SC 1 36.198 203,042 SC 1 40.833 296,529SC 2 33.654 948,455 SC 2 39.006 241,246 SC 2 41.459 311,078SC 3 33.428 940,237 SC 3 39.364 244,204 SC 3 42.471 326,918SC 4 33.450 912,967 SC 4 39.101 229,314 SC 4 43.191 342,954SC 5 32.875 888,039 SC 5 38.851 226,913 SC 5 42.682 329,974SC 6 33.309 909,297 SC 6 38.943 227,642 SC 6 43.403 340,659SC 7 31.956 860,866 SC 7 34.216 179,170 SC 7 39.317 266,498SC 8 31.686 826,730 SC 8 34.805 190,010 SC 8 38.949 261,639SC 9 33.366 906,837 SC 9 38.980 229,254 SC 9 43.410 340,619PR 1 30.685 812,504 PR 1 27.186 115,754PR 2 33.021 895,843 PR 2 32.658 162,552PR 3 34.001 967,693 PR 3 31.542 160,838PR 4 35.360 1,053,785 PR 4 31.861 169,800PR 5 34.554 1,017,134 PR 5 35.089 208,200PR 6 32.615 908,844 PR 6 35.942 210,029PR 7 33.091 938,448 PR 7 38.402 233,937PR 8 34.856 1,026,372 PR 8 36.449 224,403PR 9 34.693 1,013,802 PR 9 36.990 230,534PR 10 35.221 1,059,690 PR 10 32.478 176,955PR 11 32.322 873,498 PR 11 33.466 183,168PR 12 35.542 1,056,349 PR 12 32.137 173,127

* Highlighted cells contain the largest values for each group ** Storm centers in bold are the critical storm centers

As can be seen in Table 7-9, the Basin 1 Only PMP results in more intense precipitation for Basin 1 compared to the Overall PMP. Therefore, Basin 1 Only PMP is used for Basin 1 and Overall PMP is used for Basins 2, 3 and 4 for the PMF calculation in order to determine the maximum water surface elevation at the CPNPP Units 3 and 4.

Table 7-9 shows, that the maximum runoff at the outfall from the overall watershed, junction of Paluxy River and Squaw Creek, results from the storm located at storm center PR10. The maximum inflow into the Squaw Creek Reservoir, which will result in the highest water surface elevation, occurs for the



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storm located in SC4 for the Basin 1 Only PMP. PR10 and SC4 are the critical storm centers for Overall PMP and Basin 1 Only PMP, respectively.

The runoff estimates to determine the critical storm center that are presented in Table 7-9 utilize the default HMR 52 (Reference 5) temporal distribution.

The critical temporal distribution of the PMP for each critical storm center is determined by watershed rainfall runoff analysis using HEC-HMS (Reference 6). In order to reduce the number of distributions for evaluation, four distributions were chosen that bracket the range of possible hyetographs. The four temporal distributions are one-third peaking event, center peaking event, two-thirds peaking event, and end peaking event. Results are summarized in Tables 7-10 and 7-11, which show the runoff obtained using the four distributions for the Paluxy River and Squaw Creek watersheds.

The analysis (Table 7-10) shows that storm center PR 10 and two-thirds temporal distribution is the critical storm distribution for the combined watershed for Paluxy River and Squaw Creek because it results in higher runoff at the confluence of the Squaw Creek and the Paluxy River watersheds.

Similarly, the analysis (Table 7-11) shows that the storm center SC 4 and two-thirds temporal distribution for the Squaw Creek Reservoir PMP (Basin 1 Only PMP) results in the higher outflow from the Squaw Creek Reservoir, which will result in the higher water surface elevation for the Squaw Creek Reservoir.

Table 7-10. Rainfall-Runoff Analysis for Overall Watershed Using HEC-HMS and Overall PMP with Four Temporal Distributions at the Critical Storm Center PR 10

Peak Flow at Junction of Paluxy River & Squaw Creek Overall PMP, Critical Storm Center (PR 10)

Temporal Distribution Peak Outflow (cfs) One-Third 1,034,566

Center 1,037,387 Two-Thirds 1,038,762

End** 952,095 * Highlighted cell contains the largest value of peak outflow ** The time period is changed from 10 days to 13 days in the model to capture the peak runoff

Table 7-11. Rainfall-Runoff Analysis for Squaw Creek Reservoir Watershed (Basin 1) Using HEC-HMS and Basin 1 Only PMP with Four Temporal Distributions at the Critical Storm Center SC 4

Peak Flow at Squaw Creek Reservoir Basin 1 Only PMP, Critical Storm Center (SC4)

Temporal Distribution Peak Inflow (cfs) Peak Outflow (cfs) One-Third 342,954 215,105

Center 342,954 217,231 Two-Thirds 342,954 218,206

End** 331,773 214,139 * Highlighted cell contains the largest value of peak outflow ** The time period is changed from 10 days to 13 days in the model to capture the peak runoff



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Tables 7-12 through 7-15 show the hourly incremental and cumulative values of Overall PMP for the default HMR 52 (Reference 5) temporal distribution with the critical storm center at PR 10 for each basin.

Table 7-16 shows the hourly incremental and cumulative values of Squaw Creek Reservoir PMP (Basin 1 Only PMP) for the default HMR 52 (Reference 5) temporal distribution with the critical storm center at SC 4 for the Squaw Creek Reservoir watershed (Basin 1 Only).

The temporally distributed hourly PMP values for the critical temporal distribution at the critical storm centers are tabulated and plotted below.

Tables 7-17 through 7-20 present the hourly PMP values for each basin for the Overall PMP with critical storm center PR 10 and critical temporal distribution (two-thirds). The corresponding hyetographs are shown in Figures 7-4 through 7-7. The cumulative mass curves comparing all four temporal distributions are shown in Figures 7-8 through 7-11.

Table 7-21 presents the hourly PMP values for Basin 1 for the Squaw Creek Reservoir PMP (Basin 1 Only PMP) with the critical storm center SC 4 and critical temporal distribution (two-thirds). The corresponding hyetograph is shown in Figure 7-12. The cumulative mass curves comparing all four temporal distributions are shown in Figure 7-13.

The hourly values for each basin for all four temporal distributions with corresponding hyetographs are included in Attachment B.



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Table 7-12. Basin 1 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), HMR 52 Temporal Distribution

Time Precipitation (inches) Time Precipitation (inches) (hours) Incremental Cumulative (hours) Incremental Cumulative

1 0.097 0.097 37 1.322 11.218 2 0.097 0.194 38 1.949 13.167 3 0.097 0.291 39 2.818 15.985 4 0.097 0.388 40 5.604 21.589 5 0.097 0.485 41 2.432 24.021 6 0.097 0.582 42 1.742 25.763 7 0.118 0.700 43 0.545 26.308 8 0.118 0.818 44 0.502 26.810 9 0.118 0.936 45 0.464 27.274 10 0.118 1.054 46 0.432 27.706 11 0.118 1.172 47 0.407 28.113 12 0.118 1.290 48 0.387 28.500 13 0.150 1.440 49 0.251 28.751 14 0.150 1.590 50 0.251 29.002 15 0.150 1.740 51 0.251 29.253 16 0.150 1.890 52 0.251 29.504 17 0.150 2.040 53 0.251 29.755 18 0.150 2.190 54 0.251 30.006 19 0.205 2.395 55 0.173 30.179 20 0.205 2.600 56 0.173 30.352 21 0.205 2.805 57 0.173 30.525 22 0.205 3.010 58 0.173 30.698 23 0.205 3.215 59 0.173 30.871 24 0.205 3.420 60 0.173 31.044 25 0.288 3.708 61 0.132 31.176 26 0.299 4.007 62 0.132 31.308 27 0.313 4.320 63 0.132 31.440 28 0.329 4.649 64 0.132 31.572 29 0.347 4.996 65 0.132 31.704 30 0.368 5.364 66 0.132 31.836 31 0.586 5.950 67 0.107 31.943 32 0.632 6.582 68 0.107 32.050 33 0.694 7.276 69 0.107 32.157 34 0.773 8.049 70 0.107 32.264 35 0.868 8.917 71 0.107 32.371 36 0.979 9.896 72 0.107 32.478



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1 0.100 0.100 37 1.331 11.467 2 0.100 0.200 38 1.952 13.419 3 0.100 0.300 39 2.872 16.291 4 0.100 0.400 40 6.073 22.364 5 0.100 0.500 41 2.452 24.816 6 0.100 0.600 42 1.741 26.557 7 0.121 0.721 43 0.558 27.115 8 0.121 0.842 44 0.513 27.628 9 0.121 0.963 45 0.474 28.102 10 0.121 1.084 46 0.442 28.544 11 0.121 1.205 47 0.416 28.960 12 0.121 1.326 48 0.396 29.356 13 0.153 1.479 49 0.257 29.613 14 0.153 1.632 50 0.257 29.870 15 0.153 1.785 51 0.257 30.127 16 0.153 1.938 52 0.257 30.384 17 0.153 2.091 53 0.257 30.641 18 0.153 2.244 54 0.257 30.898 19 0.209 2.453 55 0.177 31.075 20 0.209 2.662 56 0.177 31.252 21 0.209 2.871 57 0.177 31.429 22 0.209 3.080 58 0.177 31.606 23 0.209 3.289 59 0.177 31.783 24 0.209 3.498 60 0.177 31.960 25 0.295 3.793 61 0.135 32.095 26 0.306 4.099 62 0.135 32.230 27 0.320 4.419 63 0.135 32.365 28 0.337 4.756 64 0.135 32.500 29 0.355 5.111 65 0.135 32.635 30 0.376 5.487 66 0.135 32.770 31 0.602 6.089 67 0.109 32.879 32 0.650 6.739 68 0.109 32.988 33 0.715 7.454 69 0.109 33.097 34 0.794 8.248 70 0.109 33.206 35 0.889 9.137 71 0.109 33.315 36 0.999 10.136 72 0.109 33.424



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1 0.102 0.102 37 1.435 11.945 2 0.102 0.204 38 2.141 14.086 3 0.102 0.306 39 3.223 17.309 4 0.102 0.408 40 7.288 24.597 5 0.102 0.510 41 2.727 27.324 6 0.102 0.612 42 1.9 29.224 7 0.123 0.735 43 0.576 29.800 8 0.123 0.858 44 0.527 30.327 9 0.123 0.981 45 0.486 30.813 10 0.123 1.104 46 0.451 31.264 11 0.123 1.227 47 0.424 31.688 12 0.123 1.350 48 0.404 32.092 13 0.157 1.507 49 0.262 32.354 14 0.157 1.664 50 0.262 32.616 15 0.157 1.821 51 0.262 32.878 16 0.157 1.978 52 0.262 33.140 17 0.157 2.135 53 0.262 33.402 18 0.157 2.292 54 0.262 33.664 19 0.214 2.506 55 0.181 33.845 20 0.214 2.720 56 0.181 34.026 21 0.214 2.934 57 0.181 34.207 22 0.214 3.148 58 0.181 34.388 23 0.214 3.362 59 0.181 34.569 24 0.214 3.576 60 0.181 34.750 25 0.301 3.877 61 0.138 34.888 26 0.313 4.190 62 0.138 35.026 27 0.327 4.517 63 0.138 35.164 28 0.344 4.861 64 0.138 35.302 29 0.363 5.224 65 0.138 35.440 30 0.385 5.609 66 0.138 35.578 31 0.625 6.234 67 0.112 35.690 32 0.680 6.914 68 0.112 35.802 33 0.751 7.665 69 0.112 35.914 34 0.839 8.504 70 0.112 36.026 35 0.943 9.447 71 0.112 36.138 36 1.063 10.510 72 0.112 36.250



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1 0.100 0.100 37 1.44 11.779 2 0.100 0.200 38 2.16 13.939 3 0.100 0.300 39 3.206 17.145 4 0.100 0.400 40 6.934 24.079 5 0.100 0.500 41 2.736 26.815 6 0.100 0.600 42 1.919 28.734 7 0.121 0.721 43 0.568 29.302 8 0.121 0.842 44 0.52 29.822 9 0.121 0.963 45 0.478 30.300 10 0.121 1.084 46 0.444 30.744 11 0.121 1.205 47 0.417 31.161 12 0.121 1.326 48 0.397 31.558 13 0.154 1.480 49 0.257 31.815 14 0.154 1.634 50 0.257 32.072 15 0.154 1.788 51 0.257 32.329 16 0.154 1.942 52 0.257 32.586 17 0.154 2.096 53 0.257 32.843 18 0.154 2.250 54 0.257 33.100 19 0.210 2.460 55 0.177 33.277 20 0.210 2.670 56 0.177 33.454 21 0.210 2.880 57 0.177 33.631 22 0.210 3.090 58 0.177 33.808 23 0.210 3.300 59 0.177 33.985 24 0.210 3.510 60 0.177 34.162 25 0.295 3.805 61 0.135 34.297 26 0.307 4.112 62 0.135 34.432 27 0.321 4.433 63 0.135 34.567 28 0.337 4.770 64 0.135 34.702 29 0.356 5.126 65 0.135 34.837 30 0.378 5.504 66 0.135 34.972 31 0.615 6.119 67 0.109 35.081 32 0.668 6.787 68 0.109 35.190 33 0.739 7.526 69 0.109 35.299 34 0.827 8.353 70 0.109 35.408 35 0.932 9.285 71 0.109 35.517 36 1.054 10.339 72 0.109 35.626



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Table 7-16. Basin 1 Hourly PMP – Basin 1 Only PMP, Critical Storm Center (SC 4), HMR 52 Temporal Distribution


1 0.098 0.098 37 1.572 12.696 2 0.098 0.196 38 2.34 15.036 3 0.098 0.294 39 3.806 18.842 4 0.098 0.392 40 12.146 30.988 5 0.098 0.490 41 3.088 34.076 6 0.098 0.588 42 2.053 36.129 7 0.120 0.708 43 0.615 36.744 8 0.120 0.828 44 0.554 37.298 9 0.120 0.948 45 0.504 37.802 10 0.120 1.068 46 0.464 38.266 11 0.120 1.188 47 0.433 38.699 12 0.120 1.308 48 0.412 39.111 13 0.153 1.461 49 0.261 39.372 14 0.153 1.614 50 0.261 39.633 15 0.153 1.767 51 0.261 39.894 16 0.153 1.920 52 0.261 40.155 17 0.153 2.073 53 0.261 40.416 18 0.153 2.226 54 0.261 40.677 19 0.211 2.437 55 0.177 40.854 20 0.211 2.648 56 0.177 41.031 21 0.211 2.859 57 0.177 41.208 22 0.211 3.070 58 0.177 41.385 23 0.211 3.281 59 0.177 41.562 24 0.211 3.492 60 0.177 41.739 25 0.301 3.793 61 0.134 41.873 26 0.314 4.107 62 0.134 42.007 27 0.329 4.436 63 0.134 42.141 28 0.347 4.783 64 0.134 42.275 29 0.368 5.151 65 0.134 42.409 30 0.392 5.543 66 0.134 42.543 31 0.687 6.230 67 0.108 42.651 32 0.772 7.002 68 0.108 42.759 33 0.866 7.868 69 0.108 42.867 34 0.970 8.838 70 0.108 42.975 35 1.082 9.920 71 0.108 43.083 36 1.204 11.124 72 0.108 43.191



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Table 7-17. Basin 1 Hourly PMP - Overall PMP, Critical Storm Center (PR 10), Critical Temporal Distribution (Two-Thirds)

Duration Depth Duration Depth Duration Depth Increm. Increm. Increm.

hrs in hrs in hrs in 1 0.097 25 0.1500 49 2.4320 2 0.097 26 0.1500 50 1.7420 3 0.097 27 0.2050 51 0.5450 4 0.097 28 0.2050 52 0.5020 5 0.097 29 0.2050 53 0.4640 6 0.097 30 0.2050 54 0.4320 7 0.107 31 0.2050 55 0.4070 8 0.107 32 0.2050 56 0.3870 9 0.107 33 0.2880 57 0.2510

10 0.107 34 0.2990 58 0.2510 11 0.107 35 0.3130 59 0.2510 12 0.107 36 0.3290 60 0.2510 13 0.118 37 0.3470 61 0.2510 14 0.118 38 0.3680 62 0.2510 15 0.118 39 0.5860 63 0.1730 16 0.118 40 0.6320 64 0.1730 17 0.118 41 0.6940 65 0.1730 18 0.118 42 0.7730 66 0.1730 19 0.132 43 0.8680 67 0.1730 20 0.132 44 0.9790 68 0.1730 21 0.150 45 1.3220 69 0.1320 22 0.150 46 1.9490 70 0.1320 23 0.150 47 2.8180 71 0.1320 24 0.150 48 5.6040 72 0.1320

Figure 7-4. Basin 1 Hyetograph - Overall PMP, Critical Storm Center (PR 10), Critical Temporal Distribution (Two-Thirds)



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10 0.109 34 0.3060 58 0.2570 11 0.109 35 0.3200 59 0.2570 12 0.109 36 0.3370 60 0.2570 13 0.121 37 0.3550 61 0.2570 14 0.121 38 0.3760 62 0.2570 15 0.121 39 0.6020 63 0.1770 16 0.121 40 0.6500 64 0.1770 17 0.121 41 0.7150 65 0.1770 18 0.121 42 0.7940 66 0.1770 19 0.135 43 0.8890 67 0.1770 20 0.135 44 0.9990 68 0.1770 21 0.153 45 1.3310 69 0.1350 22 0.153 46 1.9520 70 0.1350 23 0.153 47 2.8720 71 0.1350 24 0.153 48 6.0730 72 0.1350




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10 0.112 34 0.3130 58 0.2620 11 0.112 35 0.3270 59 0.2620 12 0.112 36 0.3440 60 0.2620 13 0.123 37 0.3630 61 0.2620 14 0.123 38 0.3850 62 0.2620 15 0.123 39 0.6250 63 0.1810 16 0.123 40 0.6800 64 0.1810 17 0.123 41 0.7510 65 0.1810 18 0.123 42 0.8390 66 0.1810 19 0.138 43 0.9430 67 0.1810 20 0.138 44 1.0630 68 0.1810 21 0.157 45 1.4350 69 0.1380 22 0.157 46 2.1410 70 0.1380 23 0.157 47 3.2230 71 0.1380 24 0.157 48 7.2880 72 0.1380




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10 0.109 34 0.3070 58 0.2570 11 0.109 35 0.3210 59 0.2570 12 0.109 36 0.3370 60 0.2570 13 0.121 37 0.3560 61 0.2570 14 0.121 38 0.3780 62 0.2570 15 0.121 39 0.6150 63 0.1770 16 0.121 40 0.6680 64 0.1770 17 0.121 41 0.7390 65 0.1770 18 0.121 42 0.8270 66 0.1770 19 0.135 43 0.9320 67 0.1770 20 0.135 44 1.0540 68 0.1770 21 0.154 45 1.4400 69 0.1350 22 0.154 46 2.1600 70 0.1350 23 0.154 47 3.2060 71 0.1350 24 0.154 48 6.9340 72 0.1350




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Figure 7-8. Basin 1 Mass Curve - Overall PMP, Critical Storm Center (PR 10), Critical Temporal Distribution (Two-Thirds)




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Table 7-21. Basin 1 Hourly PMP – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal Distribution (Two-Thirds)



10 0.108 34 0.3140 58 0.2610 11 0.108 35 0.3290 59 0.2610 12 0.108 36 0.3470 60 0.2610 13 0.120 37 0.3680 61 0.2610 14 0.120 38 0.3920 62 0.2610 15 0.120 39 0.6870 63 0.1770 16 0.120 40 0.7720 64 0.1770 17 0.120 41 0.8660 65 0.1770 18 0.120 42 0.9700 66 0.1770 19 0.134 43 1.0820 67 0.1770 20 0.134 44 1.2040 68 0.1770 21 0.153 45 1.5720 69 0.1340 22 0.153 46 2.3400 70 0.1340 23 0.153 47 3.8060 71 0.1340 24 0.153 48 12.1460 72 0.1340

Figure 7-12. Basin 1 Hyetograph – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal Distribution (Two-Thirds)



REV. 4

PAGE NO. 36 of 36

Figure 7-13. Basin 1 Mass Curve – Basin 1 Only PMP, Critical Storm Center (SC 4), Critical Temporal Distribution (Two-Thirds)

8.0 Appendices

Appendix A contains the resulting HMR 52 software output file. The output file also includes the input data.

Appendix B contains the resulting hourly PMP values for all four temporal distributions with corresponding hyetographs.

B1SC1

1***************************************** ***************************************

* * * *

* PROBABLE MAXIMUM STORM (HMR52) * * U.S. ARMY CORPS OF ENGINEERS *

* NOVEMBER 1982 * * THE HYDROLOGIC ENGINEERING CENTER *

* REVISED APRIL 91 * * 609 SECOND STREET *

* * * DAVIS, CALIFORNIA 95616 *

* RUN DATE 12/21/2012 TIME 10:57:08 * * (916) 551-1748 OR (FTS) 460-1748 *

* * * *

***************************************** ***************************************

H H M M RRRRRR 5555555 22222

H H MM MM R R 5 2 2

H H M M M M R R 5 2

HHHHHHH M M M RRRRRR 555555 2

H H M M R R 5 2

H H M M R R 5 5 2

H H M M R R 55555 2222222

1 HEC PROBABLE MAXIMUM STORM (HMR52) INPUT DATA PAGE 1

LINE ID.......1.......2.......3.......4.......5.......6.......7.......8.......9......10

1 ID

HMR52 INPUT DATA FOR CPNPP UNITS 3 & 4 PMP CALCULATION BASIN 1 ONLY

2 ID

ANALYSIS PERFORMED BY LANA LAWRENCE ENERCON SERVICES INC 12-21-2012

3 ID

STORM CENTER AT B1SC1

4 BN CPNPP

5 ID CALCULATE STORM OVER ENTIRE AREA

6 BS 1

7 BX 18.958 19.759 20.895 21.958 22.767 23.302 23.939 24.553 25.676 26.500

8 BX 27.709 28.719 29.261 29.784 30.116 30.430 31.870 32.330 31.812 31.110

9 BX 30.640 30.533 30.330 30.169 30.051 29.880 29.634 29.527 29.431 29.136

10 BX 28.728 27.601 27.130 26.697 26.251 26.177 25.517 25.040 24.319 23.552

11 BX 23.197 23.040 22.326 21.785 20.876 20.332 19.358 19.243 19.018 18.857

12 BX 19.038

13 BY 21.897 21.713 20.536 21.245 20.921 21.017 20.342 20.381 19.859 19.081

14 BY 19.059 18.695 17.199 17.321 16.995 17.300 16.325 14.535 13.442 12.663

15 BY 12.235 11.764 11.646 11.721 11.518 11.497 11.732 11.743 11.604 11.669

16 BY 12.065 12.263 12.684 12.721 13.749 14.158 14.512 14.654 15.061 14.901

17 BY 14.995 15.427 15.792 17.109 17.692 18.479 19.580 20.213 20.238 21.088

18 BY 21.542

19 HO 216

20 HP 10 29.83 36.09 41.33 46.33 49.01

21 HP 200 22.33 27.19 32.65 36.76 40.45

22 HP 1000 16.19 21.18 26.21 30.62 33.88

23 HP 5000 9.35 13.05 17.90 22.39 25.42

24 HP 10000 7.11 10.35 14.58 18.67 21.76

25 HP 20000 5.20 8.23 11.64 15.27 18.11

26 PL 3

27 SA 0 0 3

28 SC 30.467 12.852

29 ST 60 0.304 0 1

30 PU ON

31 ZZ

1***************************************** ***************************************

* * * *

* PROBABLE MAXIMUM STORM (HMR52) * * U.S. ARMY CORPS OF ENGINEERS *

* NOVEMBER 1982 * * THE HYDROLOGIC ENGINEERING CENTER *

Page 1

B1SC1

* REVISED APRIL 91 * * 609 SECOND STREET *

* * * DAVIS, CALIFORNIA 95616 *

* RUN DATE 12/21/2012 TIME 10:57:08 * * (916) 551-1748 OR (FTS) 460-1748 *

* * * *

***************************************** ***************************************

HMR52 INPUT DATA FOR CPNPP UNITS 3 & 4 PMP CALCULATION BASIN 1 ONLY

ANALYSIS PERFORMED BY LANA LAWRENCE ENERCON SERVICES INC 12-21-2012

STORM CENTER AT B1SC1

CALCULATE STORM OVER ENTIRE AREA

PMP DEPTHS FROM HMR 51

AREA DURATION

(SQ. MI.) 6-HR 12-HR 24-HR 48-HR 72-HR

10. 29.83 36.09 41.33 46.33 49.01

200. 22.33 27.19 32.65 36.76 40.45

1000. 16.19 21.18 26.21 30.62 33.88

5000. 9.35 13.05 17.90 22.39 25.42

10000. 7.11 10.35 14.58 18.67 21.76

20000. 5.20 8.23 11.64 15.27 18.11

STORM AREA PMP DEPTHS FOR 6-HOUR INCREMENTS

10. 29.74 6.30 3.17 2.13 1.61 1.30 1.08 .93 .82 .73 .65 .60

25. 27.99 5.98 3.12 2.12 1.61 1.30 1.09 .94 .82 .73 .66 .60

50. 26.53 5.74 3.07 2.11 1.61 1.30 1.09 .94 .83 .74 .67 .61

100. 24.40 5.36 3.00 2.10 1.61 1.31 1.10 .95 .84 .75 .68 .62

175. 22.67 5.08 2.94 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

300. 20.71 5.01 2.91 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62

450. 19.17 5.01 2.90 2.05 1.59 1.30 1.09 .95 .84 .75 .68 .62

700. 17.49 5.02 2.89 2.04 1.57 1.28 1.08 .94 .83 .74 .67 .61

1000. 16.13 5.01 2.88 2.03 1.56 1.28 1.08 .93 .82 .73 .66 .61

1500. 14.41 4.72 2.80 2.00 1.56 1.27 1.08 .94 .83 .74 .67 .61

2150. 12.87 4.48 2.74 1.98 1.55 1.27 1.08 .94 .83 .74 .67 .62

3000. 11.44 4.26 2.67 1.95 1.54 1.27 1.08 .94 .83 .75 .68 .62

4500. 9.71 4.00 2.59 1.92 1.53 1.27 1.08 .95 .84 .75 .68 .63

6500. 8.42 3.70 2.46 1.85 1.48 1.23 1.06 .92 .82 .74 .67 .62

10000. 7.06 3.32 2.28 1.74 1.40 1.18 1.01 .89 .79 .72 .65 .60

15000. 5.99 3.05 2.10 1.61 1.30 1.09 .94 .83 .74 .67 .61 .56

20000. 5.23 2.87 1.98 1.51 1.23 1.03 .89 .78 .70 .63 .57 .53

1 BOUNDARY COORDINATES FOR CPNPP

X 19.0 19.8 20.9 22.0 22.8 23.3 23.9 24.6 25.7 26.5

Y 21.9 21.7 20.5 21.2 20.9 21.0 20.3 20.4 19.9 19.1

X 27.7 28.7 29.3 29.8 30.1 30.4 31.9 32.3 31.8 31.1

Y 19.1 18.7 17.2 17.3 17.0 17.3 16.3 14.5 13.4 12.7

X 30.6 30.5 30.3 30.2 30.1 29.9 29.6 29.5 29.4 29.1

Y 12.2 11.8 11.6 11.7 11.5 11.5 11.7 11.7 11.6 11.7

Page 2

B1SC1

X 28.7 27.6 27.1 26.7 26.3 26.2 25.5 25.0 24.3 23.6

Y 12.1 12.3 12.7 12.7 13.7 14.2 14.5 14.7 15.1 14.9

X 23.2 23.0 22.3 21.8 20.9 20.3 19.4 19.2 19.0 18.9

Y 15.0 15.4 15.8 17.1 17.7 18.5 19.6 20.2 20.2 21.1

X 19.0

Y 21.5

SCALE = 1.0000 MILES PER COORDINATE UNIT

BASIN AREA = 64.3 SQ. MI.

BASIN CENTROID COORDINATES, X = 26.1, Y = 16.7

1

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B1SC1

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1 VARYING STORM AREA SIZE AND FIXED ORIENTATION

SUM OF DEPTHS

ORIEN- FOR 3 PEAK

STORM AREA TATION BASIN-AVERAGED INCREMENTAL DEPTHS FOR 6-HR PERIODS 6-HR PERIODS

10. 309. 15.47 3.29 1.66 1.12 .85 .68 .57 .49 .43 .38 .34 .31 20.42

25. 309. 18.90 4.31 2.28 1.55 1.18 .95 .80 .68 .60 .54 .48 .44 25.49

50. 309. 21.29 4.92 2.65 1.82 1.39 1.13 .94 .81 .72 .64 .58 .52 28.86

100. 309. 22.55 5.11 2.87 2.00 1.54 1.25 1.05 .91 .80 .72 .65 .59 30.53

175. 309. 22.91 5.09 2.93 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62 30.93

300. 309. 22.51 5.17 2.94 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62 30.61

450. 309. 21.72 5.20 2.91 2.03 1.57 1.28 1.09 .94 .83 .74 .67 .61 29.83

700. 309. 20.78 5.22 2.87 1.99 1.54 1.25 1.06 .92 .81 .72 .65 .60 28.87

1000. 309. 19.96 5.21 2.82 1.95 1.50 1.23 1.03 .90 .79 .70 .64 .58 28.00

1500. 309. 18.76 4.83 2.68 1.87 1.45 1.19 1.01 .87 .77 .69 .62 .57 26.28

2150. 309. 17.42 4.47 2.53 1.77 1.39 1.14 .97 .84 .74 .67 .60 .55 24.41

3000. 309. 15.89 4.07 2.35 1.66 1.31 1.08 .92 .80 .71 .64 .58 .53 22.32

4500. 309. 14.92 3.88 2.29 1.63 1.30 1.08 .92 .80 .71 .64 .58 .53 21.08

6500. 309. 14.27 3.63 2.18 1.57 1.26 1.05 .90 .79 .70 .63 .57 .52 20.08

10000. 309. 13.38 3.31 2.03 1.48 1.19 1.00 .86 .76 .68 .61 .56 .51 18.71

15000. 309. 12.59 3.09 1.88 1.37 1.11 .93 .80 .70 .63 .57 .52 .47 17.56

20000. 309. 11.77 2.92 1.78 1.29 1.04 .88 .76 .66 .59 .54 .49 .45 16.47

FIXED STORM AREA SIZE AND VARYING ORIENTATION

SUM OF DEPTHS

ORIEN- FOR 3 PEAK

STORM AREA TATION BASIN-AVERAGED INCREMENTAL DEPTHS FOR 6-HR PERIODS 6-HR PERIODS

175. 140. 22.52 5.04 2.90 2.04 1.58 1.29 1.09 .94 .83 .74 .67 .61 30.46

175. 150. 21.68 4.91 2.84 2.00 1.55 1.26 1.07 .92 .81 .73 .66 .60 29.43

175. 160. 20.61 4.73 2.74 1.93 1.50 1.22 1.03 .89 .79 .70 .64 .58 28.09

175. 170. 19.53 4.55 2.65 1.86 1.44 1.18 .99 .86 .76 .68 .61 .56 26.73

175. 180. 18.62 4.39 2.56 1.80 1.39 1.14 .96 .83 .73 .66 .59 .54 25.57

175. 190. 17.87 4.26 2.49 1.75 1.36 1.11 .94 .81 .71 .64 .58 .53 24.62

175. 200. 17.32 4.16 2.44 1.72 1.33 1.09 .92 .79 .70 .63 .57 .52 23.92

175. 210. 16.96 4.10 2.41 1.69 1.31 1.07 .90 .78 .69 .62 .56 .51 23.46

175. 220. 16.80 4.07 2.40 1.69 1.31 1.07 .90 .78 .69 .61 .56 .51 23.26

175. 230. 16.86 4.09 2.41 1.70 1.31 1.07 .90 .78 .69 .62 .56 .51 23.36

175. 240. 17.17 4.15 2.44 1.72 1.33 1.09 .92 .80 .70 .63 .57 .52 23.76

175. 250. 17.70 4.25 2.50 1.76 1.36 1.11 .94 .81 .72 .64 .58 .53 24.45

175. 260. 18.51 4.40 2.58 1.82 1.41 1.15 .97 .84 .74 .66 .60 .55 25.49

175. 270. 19.53 4.58 2.68 1.89 1.46 1.19 1.01 .87 .77 .69 .62 .57 26.79

175. 280. 20.72 4.78 2.78 1.96 1.52 1.24 1.05 .91 .80 .71 .65 .59 28.27

175. 290. 21.89 4.96 2.87 2.02 1.57 1.28 1.08 .94 .82 .74 .67 .61 29.72

Page 4

B1SC1

175. 300. 22.67 5.06 2.92 2.06 1.59 1.30 1.10 .95 .84 .75 .68 .62 30.66

175. 310. 22.91 5.09 2.93 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62 30.92

175. 304. 22.82 5.08 2.92 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62 30.83

175. 314. 22.86 5.08 2.92 2.06 1.60 1.30 1.10 .95 .84 .75 .68 .62 30.86

1 PROBABLE MAXIMUM STORM FOR CPNPP

STORM AREA = 175. SQ. MI., ORIENTATION = 309., PREFERRED ORIENTATION = 216.

STORM CENTER COORDINATES, X = 30.5, Y = 12.9

AREA

ISOHYET WITHIN

AREA BASIN DEPTHS (INCHES) FOR 6-HOUR INCREMENTS OF PMS

(SQ.MI.) (SQ.MI.) 1 2 3 4 5 6 7 8 9 10 11 12

A 10. 6. 26.98 5.58 3.02 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

B 25. 14. 25.16 5.33 2.98 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

C 50. 26. 23.35 5.15 2.94 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

D 100. 43. 21.76 4.95 2.92 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

E 175. 59. 20.18 4.82 2.91 2.08 1.61 1.31 1.11 .96 .85 .76 .68 .63

F 300. 64. 14.96 4.01 2.44 1.73 1.34 1.09 .92 .80 .70 .63 .57 .52

G 450. 64. 12.01 3.38 2.09 1.48 1.14 .93 .79 .68 .60 .54 .49 .44

H 700. 64. 9.52 2.87 1.75 1.22 .94 .77 .65 .56 .50 .44 .40 .37

I 1000. 64. 7.71 2.39 1.50 1.06 .82 .67 .57 .49 .43 .39 .35 .32

J 1500. 64. 5.89 1.95 1.29 .91 .71 .58 .49 .42 .37 .33 .30 .28

K 2150. 64. 4.53 1.52 1.03 .73 .56 .46 .39 .34 .30 .27 .24 .22

L 3000. 64. 3.40 1.17 .78 .55 .43 .35 .29 .25 .22 .20 .18 .17

M 4500. 64. 2.04 .74 .53 .37 .29 .24

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