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Ilk report was prepared by Kathy Derouin, Lois Schneider, and Mary LouKeigher, Group H-8.

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government.Neither the United .%.tes Ccwernmcnt nor aoy agency thereof, nor any of theu employees, makes anywarranty, express or implied, or aaaumesany lcgat liability or responsibility ror the accuracy, comp!c!encss,LSrusefulnessof any information, apparatus, product, or processdisclosed, or represents that I!S usc wouldnot infringe privately owned rights, Rct_crenccsherein to any specilk commercial product, prcsccaa,orWCC by trade name, trademark, rrsarsufacturer,or otherwise, does not nccesaady constitute or imply itsendorsement, recommen&tion, or favoring by the United States Government or any agency thereof. Theview and opintons of authors expressed herein do not necessarily state or reflect those of the United

SLSLCSCovesnrncnt or any agency thereof.

.

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LA-9445 -PNTX-A

Issued: December 1982

Supplementary Documentation for anEnvironmental Impact Statement

Regarding the Pantex Plant

Hydrologic Study for Pantex

N. M. BeckerW. D. Purtymun

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-.aboratorvLos Alamos NationalLosAlamos,New Mexico 87545

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ABOUT THIS REPORT

This official electronic version was created by scanning the best available paper or microfiche copy of the original report at a 300 dpi resolution. Original color illustrations appear as black and white images. For additional information or comments, contact: Library Without Walls Project Los Alamos National Laboratory Research Library Los Alamos, NM 87544 Phone: (505)667-4448 E-mail: [email protected]

CONTENTS

ABSTRACT 1

I. INTRODUCTION

II. DRAINAGE PATTERNS AND RAINFALL-RUNOFF RELATIONSHIPSA. Delineation of Drainage Patterns on the Pantex Plant and

Texas Tech University Research FarmlandsB. Rainfall at Pantex and Runoff into Playa Basinsc. Flooding in the Playa Basins from the 6- and 24-Hour

Design Storms

III. STUDY OF CULVERT CAPACITIES IN ZONES 11 AND 12A. Zone 12

1. Computation of Peak Discharge2. Size of Culverts to Carry Peak Discharge3. Discussion

B. Zone 11

IV. EROSION AND SEDIMENT MOVEMENT AS A RESULT OF RAINFALL RUNOFFA. MethodologyB. Resultsc. Discussion

v. SUMMARY AND CONCLUSIONS

1

22

35

666

1;11

12131314

14

ACKNOWLEDGMENTS 15

REFERENCES 15

v

FIGURES

1.

2.

3.4.5.6.

::9.

:::12.

I.II.III.Iv.v.VI.VII.VIII.IX.x.XI.XII.

Surface drainage at the Pantex Plant and Texas Tech UniversityResearch FarmLand use at the Pantex Plant and Texas Tech University ResearchFarmGraphic solution of the runoff equationPlaya basin volumeSubmerged playa basin areas for the 6- and 24-hour stormFlooding of buildings due to the 6- and 24-hour stormLocation of culverts in Zone 12Intensity-duration-frequency curves for PantexInterflow connection of culverts in Zone 12Ditch system to Playa Basin #1Location of culverts in Zone 11Interflow connection of culverts in Zone 11

TABLES

RAINFALL INTENSITIES FOR AMARILLO, TEXASCURVE NUMBERS FOR PANTEX BASINSRUNOFF VOLUMES INTO PLAYA BASINSVOLUMES ENCLOSED BY CONTOURS IN PLAYA BASINSRAINFALL INTENSITY AS A FUNCTION OF RAINFALL DURATIONPEAK DISCHARGE COMPUTATIONS FOR ZONE 12SUMMED DESIGN DISCHARGES FOR ZONE 12 - RATIONAL METHODMAXIMUM DISCHARGE OF CULVERTS - ZONE 12PEAK DISCHARGE COMPUTATIONS FOR ZONE 11MAXIMUM DISCHARGE OF CULVERTS - ZONE 11SUMMED DESIGN DISCHARGES FOR ZONE 11 - RATIONAL METHODSOIL LfISSRATES ON PLAYA BASIN #1

19

20202139404142434445

464647525253565860636465

vi

SUPPLEMENTARY DOCUMENTATION FOR AN ENVIRONMENTAL IMPACT STATEMENTREGARDING THE PANTEX PLANT:

HYDROLOGIC STUDY FOR PANTEX

by

N. M. Becker and W. D. Purtymun

ABSTRACT

This report documents work performed in support of preparation of anEnvironmental Impact Statement (EIS) regarding the Department of Energy’sPantex Plant, near Amarillo, Texas. Drainage patterns and drainage diversionat the Pantex Plant and Texas Tech University Research Farm have beendelineated. Rainfall-runoff relations for the 6- and 24-hour storms wereinvestigated using historical data. Resultant flooding onsite from thesestorms was computed. Culvert sizes in Zones 11 and 12 were investigated todetermine an adequate design size to carry storm water runoff. Erosion andsoil loss rates were computed for wheat crops and native grasses and relatedto potential for contaminant

I. INTRODUCTION

transport.

This report documents work performed in support of preparation of anEnvironmental Impact Statement (EIS) regarding the Department of Energy’s(DOE) Pantex P1ant, near Amari 110, Texas. The EIS addresses continuingnuclear weapons operations at Pantex and the construction of additionalfacilities to house those operations. The EIS was prepared in accordancewith current regulations under the National Environmental Policy Act.Regulations of the Council on Environmental Quality (40 CFR 1500) requireagencies to prepare a concise EIS with fewer than 300 pages for complexprojects. This report was prepared by Los Alamos National Laboratory todocument details of work performed and supplementary information consideredduring preparation of the Draft Environmental Impact Statement.

This report documents surface hydrologic studies performed for thePantex Plant. The Pantex Plant, located approximately 16 miles (25 km)northeast of Amarillo, Texas, is situated in a semiarid climate.Precipitation is mainly in the form of spring and summer thundershowers,

usually intense and of shortpossibility of flooding on aand 12. The effect floodingdiscussed. Chemical qualityPurtynun (1982A).

Englishmeasurementsconvenience,

units have been

duration. Therefore, this report addresses theplant-wide scale and specifically for Zones 11 -may have on plant activities is addressed andof the water is presented in Laseter (1982) and .

used throughout this report because hydrologicare typically reported in this system. For the reader’smetric conversions are listed.

To convert

FeetAcresCubic feet

per secondInchesTons per acre

Multiply by To obtain

0.3048 Meters0.4047 Hectares

Cubic meters0.0283 per second0.0254 Meters224.15 Grams per square

meter

II. DRAINAGE PATTERNS AND RAINFALL-RUNOFF RELATIONSHIPS

A. Delineation of Drainage Patterns on the Pantex Plant and TexasTech University Research Farmlands

Surface drainage at the Pantex Plant and Texas Tech University ResearchFarm is shown in Fig. 1. As is common through much of the Texas Panhandle,surface drainage is into playa basins, which are closed drainage basins.This is in contrast to the development of stream drainage networks, whichcover nearly all of the United States. For the most part, drainage on Pantexland remains within the plant boundaries. Drainage beyond the Pantex Plantboundaries occurs in Basin #1, where runoff from two north firing sitesdrains into a playa north of Farm Market Road 293. Basin #7 drains offsiteto the south, into Seven Mile Basin, a large playa basin. Because ofrerouted drainage in Zone 12, Basin #7 now consists of agricultural landonly. Small portions of Basins #5, 6, and 9, as well as an unlabeled basinlocated west of Basin #2,also drain offsite of the Plant, but in allinstances, these are perimeter portions of the Plant where land use isprimarily agricultural or fallow and are not used in conjunction with Plantoperations, Fig. 1.

There has been drainage diversion within the Plant. Area A (Fig. 1) hasbeen rerouted to Playa Basin #1 through a system of culverts and openchannels. Area B, also a built-up area, which was originally located within -Basin #7, has been rerouted to the Texas Tech University Playa Basin through

2

a culvert and open channel system. Adequate sizing of these culverts is. discussed later in this report. Area C has been rerouted from drainage Basin

#8 into Playa Basin #1, Fig. 1. Area D, which is primarily fallow land, hasbeen routed to Playa Basin #2, Fig. 1.

Within the individual basins, there has been some minor reroutingthrough the use of drainage ditches. For example, in the eastern part ofBasin #4, some natural drainage has been routed south before it flows intoPlaya Basin #l. This rerouting only lengthens the flow path and does notreroute the runoff into a different playa than it would go to otherwise.Similarly in Basin #1, runoff in the southern part of the basin has beenrerouted into a ditch system, but it still flows into the playa associatedwith Basin #1 located north of Farm Market Road 293. Although the flow pathis lengthened, the runoff is essentially not rerouted.

The Texas Tech University playa is connected by a pipeline to the IowaBeef Packers Plant, which is located a few miles west of the Pantex Plant.Iowa Beef Packers uses this pipeline occasionally to discharge wastewaterfrom its plant into the Texas Tech University playa for disposal, where it isused for irrigation on the Texas Tech Research Farm. This is the only knownpipeline that has the capability of discharging wastes produced outside ofplant boundaries into any playa basin on Pantex or the Texas Tech Universityproperty.

B. Rainfall at Pantex and Runoff into Plava Basins

This section investigates the volume of runoff produced from 6-hour and24-hour storms at the Pantex Plant and adjoining Texas Tech Research Farm.The analysis employs the Soil Conservation Service (SCS) runoff curve numbermethod for computing runoff from small agricultural watersheds and stormrainfal l-intensity-frequency data from the US Weather Bureau’s TechnicalPaper 40, a standard rainfall-intensity-frequency atlas (US Department ofCommerce 1961). Recurrence intervals of 5, 10, 25, 50, and 100 years areinvestigated. A recurrence interval of 50 years, for example, means thatthis size storm will occur on the average of once every 50 years, or it maybe interpreted to mean that the chance of occurrence of that size storm is 1in 50 (0.02) in any one year.

The SCS method for estimating direct runoff from storm rainfall is basedon a consolidation of methods used by SCS hydrologists over a period of about30 years. It may be readily applied to ungauged watersheds. It assumes thatrunoff will begin some time after the rain accumulates, and that the double-mass line curves will become asymptotic to a straight line on arithmeticgraph paper. Runoff is delayed until interception, infiltration and surfacestorage, or initial abstractions have all been satisfied. The rainfall-

.runoff relation is

.

where P = storm runoff depth in inches,S = potential maximum retention in inches, andQ = computed direct runoff in inches.

The parameter S is related to the runoff curve number (a soil variablethat is a measure of the soil’s runoff potential) by

CN =1000

37-TO ‘ where CN is the curve number.

Over 4000 soils in the United States and Puerto Rico have been assignedhydrologic classifications (Soil Conservation Service 1972). Theseclassifications, ranging from A to D in order from low to high runoffpotential, are then assigned a runoff curve number reflecting land use andantecedent soil moisture. Therefore, a rainfall intensity, a storm duration,and a curve number may be used collectively to predict a storm runoffvolume.

Methodology

Rainfall amounts at Pantex are tabulated for 6- and 24-hour storms inTable I. These values are extrapolated directly from the figures in therainfall-intensity-frequency atlas (US Department of Commerce 1961).

Curve numbers were selected according to land use and hydrologic soilgroup. All onsite soils are Pullman soils except for the playa bottoms,which are Randall soils (Jacquot 1962; Purtymun 19828). Land use at Pantexand the Texas Tech University Research Farm was delineated through the useof aerial photographs of the area, Fig. 2. Composite curve numbers weredeveloped using the methods described in the Soil Conservation ServiceNational Engineering Handbook, Section 4, Hydrology (Soil ConservationService 1972). These curve numbers, shown in Table 11, were developed forAntecedent Moisture Conditions (AMC) I, II, and III. The antecedent moistureconditions relate to the runoff potential, where AJIC 111 has the highestrunoff potential as a result of the soils being saturated from previousrainfall, and AMC I has the lowest runoff potential. ACM II is the mostcommonly used moisture condition because it is the mean moisture between verywet and very dry (Table II).

Direct runoff was determined using Fig. 3. For a particular stormhaving an associated recurrence interval, runoff is estimated using the

.

rainfall-runoff relation. This is the equivalent depth of runoff over the“ entire drainage basin.

Because it is assumed that all soils have at least some capacity for.infiltration of precipitation, runoff is rarely 100% of rainfall. On anaverage, in the US only about 30% of the precipitation volume becomesrunoff (Viessman 1977). This was not assumed to be the case for the playas,where all precipitation was considered to contribute to increased playavolume. This is because infiltration through the playas is minimal (Purtymun1982B). Therefore, tlcomputation purposes,the direct runoff waswere computed by multwhich were determined

e runoff estimate is conservative in this aspect. Forthe basins were split into playa and nonplaya areas;computed separately and then added. Runoff volumesplying the direct runoff by the basin and playa areas,by planimetry (Table III).

c. Flooding in the Playa Basins from the 6- and 24-Hour Design Storms

Using the volumes of runoff computed by the SCS method, the increase inplaya surface area was computed to determine if any hazardous flooding wouldoccur. This was performed for the 5-, 10-, 25-, 50-, and 100-yearrecurrence interval storms. For a 6-hour design storm, a recurrence intervalof, for example, 100 years would correspond to the rainfall intensity of a6-hour storm that would occur once on the average of every 100 years.

The increased submerged area, which was due to the direct runoff, wasdetermined by calculating the volume contained within each successive playacontour. Each shaded playa area on the Fig. 1 map was assumed to be 2 feetdeep. Where the contour interval is 5 feet (as it is in most instances), theincreased volume can be schematically envisioned as described by a 5-footdepth antithe corresponding surface area, Fig. 4.

The incremental volume was computed by conforming this irregularlyshaped volume into an equivalent volume rectangle. This volume was added tothe previous volume to obtain the new total volume (Table IV). These volumescontained within the contours are compared to the runoff volumes, Table 111,to determine the extension of the playa’s surface area that was due torainfall events. Frequently, the runoff volume will fall between the volumesassociated with tw contour lines; in this instance, the outer (larger)contour was chosen.

The increase in submerged playa areas for each basin that would be dueto these storms is shown by shaded areas, Fig. 5. These shaded areas

. represent the maximum area that is likely to be water covered resulting froma specified storm, because the larger contour was always selected. Theonly incidence of flooding on the plant site would be of some structures.located in Basin #2 and at some formerly used buildings located on the TexasTech University Research Farm in Basin #8, Fig. 6. Some flooding may affect

5

offsite farm houses and buildings in Basins #1 and #9 as a result of stormsthat have a recurrence interval of 10 years or longer. Flooding on Basin #7 -is not shown because runoff on the basin discharges through large (greaterthan 28-ft2 cross-sectional area) culverts under US Highway 60 to Seven Mile -Basin, a very large playa located south of US Highway 60. (Fig. 1).

Again, the projected surface volumes are conservative because it islikely that less area will be covered with water than indicated on Fig. 5.In the absence of more detailed topography for all the playas considered,this conservative approach was selected.

III. STUDY OF CULVERT CAPACITIES IN ZONES 11 AND 12

A. Zone 12

Zone 12 contains the highest concentration per unit area of buildings,walkways, barricades, and paved areas. Because of the relatively largeamount of impervious area, adequate drainage from storm runoff is anecessity. A system of culverts and open channels has been superimposed onthe natural drainage, rerouting most of the runoff and waste effluents fromthis area to Playa Basin #1. The remainder is conveyed to the Texas TechUniversity Playa Basin through a system of culverts and open channels. Theculvert is the main structure that can limit the amount of discharge; as aresult, a special study was made of the existing culvert network to see ifthe culverts were adequate in size to carry, at the minimum, the runoff fromthe 10-year storm.

A study was undertaken to determine an adequate design size of culvertsto carry the 5-, 10-, 25-, 50-, and 100-year storm water runoff. After thesizes and locations of the culverts were field checked, the drainage area foreach culvert was delineated. Design rainfall intensities were computed usingboth the Izzard and Kinematic wave formulas; then peak discharges werecomputed using the Rational Method. Where culverts emptied into downstreamculvert drainage areas, peak discharges were summed. Culvert diameters weremeasured in the field and then used to compute peak discharge capacity; thesediameters were compared with diameters required to contain the computeddesign flood discharges to determine their adequacy.

1. Computation of Peak Discharge. The location of most of the Zone 12culverts is shown in Fig. 7. Delineation of drainage areas for individualculverts was made in accordance with local topography and in agreement withfield inspection.

Peak discharges for storm recurrence intervals of 5-, 10-, 25-, 50-, and100-year events were computed using the Rational Method: .

Qp = ciA,.

where Qp = peak discharge in cubic feet per second (cfs);c = runoff coefficient (dimensionless);i = average rainfall intensity in inches per hour (in./h)

lasting for a critical period of time, tc, andknown as the time of concentration in hours; and

A = drainage area in acres.

Rainfall intensities were computed using two different formulas, theIzzard formula and the Kinematic wave formula, both of which are appropriatefor urbanized (nonagricultural or developed) areas (Ragan 1972, Linsley1972) . In both instances, one solves for the time of concentration.

Power equations relating rainfall intensity to rainfall duration/time ofconcentration were developed from the intensity-duration-freqlJency curvesdevelo ed for Amarillo (Fig. 8 and Table V).

El’These equations are of the form

i=at , where a and b are constants. The computed time of concentrationis then substituted into the equation to determine the rainfall intensity.

Izzard’s formula takes the form

t = 41 b L1/3 where iL < 500 and(c i )2/3 ‘

h = 0.0007i + Cr—— >sl/3

where t =i =q =

s“ =L =c =

duration in minutes (rein),rainfall intensity in inches per hour (in./h),retardance coefficient,dimensionless slope,maximum flow length in feet (ft), andrunoff coefficient, same as in the Rational Method.

This formula applies to small plots without well-defined channels.

1

The Kinematic wave method, which was developed from the equations ofcontinuity and momentum, takes the form

t = 56.271/ n \006 L006 / 1 \o”’+

\ci) ‘

where t =n =

s =L =c =

i =

time of concentration in seconds,Manning n, a roughness coefficient,dimensionless slope,flow length in feet (ft),runoff coefficient used in the Rational formula, andrainfall intensity in inches/hour.

Runoff coefficients, c, were estimated using information derived fromfield inspection. Manning n’s were similarly estimated, using a schemeassuming n = 0.10 for bare ground, and assigning n values for grasses usingrelationships between n values reported in the Chemicals, Runoff, and Erosionfrom Agricultural Management Systems (CREAMS) manual (Knisel 1980). TheCREAMS manual documents a series of computer models simulating rainfall,runoff, and erosion (Foster 1980). A more detailed explanation of thesemodels may be found later in this report.

Results of times of concentration, rainfall intensity, and peakdischarge for Zone 12 are presented in Table VI. In many instances, the timeof concentration and, therefore, peak discharge could not be computed usingIzzard’s formula, particularly for recurrence intervals of 10 years orgreater. This is due to the failure of the iL < 500 test. In general, thepeak discharges predicted using the Kinematic wave method tended to be largerthan those predicted by the Izzard method. However, both methods producedischarges of comparable magnitudes. ldhena choice between the twodischarges was available, the larger discharge was chosen with which to makeother comparisons.

As a check to the Rational Method using the Izzard and Kinematic waveformulas, peak discharges for the 100-year recurrence interval were computedusing a technique based on the Soil Conservation Service curve number method(Zeller 1979). Computed peak discharges from this method were larger thanthose computed by the Rational Method. Because the curve number method isbased on data from the Midwest, which has different rainfall conditions thanthe semiarid Texas Panhandle, this result is to be expected. The predictedpeak discharges from the two methods are of the same order of magnitude, andso, in this case, are considered to provide a reasonable check.

.

.

&

.

8

2. Size of Culverts to Carry Peak Discharge. The objective is to.select a pipe diameter sufficiently large to carry the maximum peak dischargeof a desired recurrence interval. Because a pipe under nonsubmerged inletconditions will carry its maximum discharge when it is flowing slightly lessthan full (Chow 1959), it is appropriate to handle this as an open channelproblem.

The Manning equation can be used as follows:

“ _ 1.49 RZ13 S1/2

n 9 (English units)

where

V = velocity in feet per second (ft/s),

n = Manning’s roughness coefficient,

F!= hydraulic radiu~, defined as area/wetted perimeter, and

s = slope of pipe (dimensionless).

The hydraulic radius R for a circular pipe flowing nearly full can bedetermined.

Rarea ~r2

= —.—- — =wetted perimeter m ‘“; ‘ ‘here r = pipe ‘adius “

Substituting,

v _ 1.49 2/3 S1/2- —

n F .

Using the continuity equation,

Q = AV = nr2V, where Q = discharge and A = cross-sectional area,.

●

9

together with the Manning equation

1.49 r 213 ~1/2 * r2Q=— –

n 2

or

Q_ 1.49 (r)813 S1J2 m

n (2)2/3 “

At this point, the existing pipe radius may besolved to find the largest discharge this part

substituted and the equationcular pipe size may carry.

Or conversely, if design discharge is known, the pipe size may be sizedby solving for r.

r = 0.34n Q 0-375.

sl/2

In some instances, culverts were not open to flow through their totaldiameter because of infilling by sediment and weeds, or by being crushed anddeformed. A combination of the Manning equation and the continuity equationwas again used, but this time, the hydraulic radius was computed assumingthat the new shape of the culvert cross section was now elliptical ratherthan circular. Culverts were assumed to fall into this category if theactual diameter was less than 80% of the nominal diameter.

If the minor half axis is taken to be a, andthen the discharge may be computed as follows:

2.365 msl/2 a113 r213 (2r2 - a2)-li6.Q=y (Eng”

the nominal radius to be r,

ish units)

There are also a number of box or rectangular culverts in Zone 12. Tocalculate the peak discharge through these, the Manning equation andcontinuity equation are again employed. If the height of the box is L andthe width W, then the hydraulic radius becomes LW/(2L + W) and the peakdischarge is

Q =(Ltf) 5/3 1.49 S112

(2L + W)2JS n “

10

.

Substituting for the measured actual diameters and the culvert slope, the. resultant discharge may be compared to the discharge computed by the Rational

Formula. The interflow connection between culverts is shown diagrammatically

9 in Fig. 9, flow to Playa Basin #1 in Fig. 10; and the summed design dis-charges for these culverts are computedVII. The maximum discharges for the CU’tabulated in Table VIII.

3. Discussion. Nearly all the CU’carry the storm water runoff associated

from the Rational Formula in Tableverts as limited by their diameter are

verts in Zone 12 are adequate towith the 100-year flood under non-

submerged inlet conditions. A comparison of the summed design discharges(Table VII) with the maximum culvert discharges (Table VIII) shows thatculverts 12-6 and 12-15 are inadequate in size to carry, under nonsubmergedinlet conditions, even Q5, the storm water associated with the 5-year flood.Culvert 12-16 will carry only Q5 under nonsubmerged inlet conditions, andprobably no larger flood.

Culvert 12-6 is a very long (170.5-ft) culvert, which runs under a pavedcourtyard and walkway. It has at least 2 elbows, a 90° turn, and a drop boxinlet at about the 2/3 point. These turns and inlet serve to increase theamount of head loss through the pipe. The maximum discharge that thisculvert can convey is about 3 cfs, whereas the computed Q5 for this culvertis 8.7 cfs. The maximum discharge was computed for a straight pipe; actualmaximum discharge will, in fact, be less because of the additional head lossdescribed above, which will serve to reduce the maximum discharge capacity.

Culverts 12-15 and 12-16 are culverts that drain under roads. Culvert12-15 can convey IJp to 7 cfs, whereas the computed Q5 is 11.9 cfs. Culvert12-16 can convey a maximum discharge of 17.4 cfs. This maximum flow liesbetween a complJted Q5 of 15.3 cfs and QIO of 20.3 cfs. If the storm runoffwere to exceed the carrying capacity of the culverts, the additional flowwould probably follow natural drainage patterns overland to the south,intersect other culverts or swales, and be conveyed to Playa Basin #1. Thisis where it would have gone had it been conveyed through culverts 12-15 and12-16.

B. Zone 11

Zone 11 at the Pantex Plant is characterized by buildings, walkways,barricades, and paved surfaces. In contrast to Zone 12, the concentration ofbuildings and paved surfaces is not as great, and much of the zone is coveredby open field. Natural drainage has been altered in much of the area by a

. system of culverts and open channels, although natural drainage over swalesalso occurs (Fig. 11). Drainage from Zone 11 is routed both to Playa Basin#l and Playa Basin #2 (Fig. 10).*

JJ

The methodology and computation techniques for determining the designdischarges for the 5-, 10-, 25-, 50-, and 100-year storms using the RationalMethod, the Izzard, and the Kinematic wave formulas for time of concentrationare the same as for Zone 12 and have been described in the previoussections. Computations for time of concentration and peak discharge areshown in Table IX. Locations of the culverts are shown in Fig. 11 and theirinterflow connections, in Fig. 12. Maximum discharges as limited by culvertdiameter are presented in Table X, and summed discharges are computed by theRational Method in Table XI.

Although maximum discharge calculations were not prepared for everyculvert in Zone 11, the main drainage culverts were covered. Comparing theresults from Tables X and XI, the existing culverts appear to be adequatelysized to convey even the 100-year flood event under nonsubmerged inletconditions. There may be occurrences in some instances of relatively smalllocalized pending, but this problem is not expected to be either severe ortroublesome.

IV. EROSION AND SEDIMENT MOVEMENT AS A RESULT OF RAINFALL RUNOFF

An analysis was undertaken to determine the amount of soil loss on theagricultural land at the Pantex Plant. Determination of the exact amount ofsoil loss is often imprecise, because the rate depends on many factors, suchas rainfall intensity and volume, antecedent moisture conditions, type ofvegetation, slope, soil characteristics, and land usage. Recognizing thislimitation, any prediction of soil loss is made with the understanding of theuncertainties in the approach and margin of error.

Perhaps the most common method of estimating soil loss is by use of theUniversal Soi1 Loss Equation (USLE) (Wischmeier 1978). An outgrowth ofequations developed to predict soil loss in the corn belt about 1940, theUSLE was developed by the Agricultural Research Service of the US Departmentof Agriculture in cooperation with Purdue University. Since then, the USLEhas been improved to account for local rainfall characteristics, quantitativesoil erodibility, and cropping and management effects. One of the majoradvantages of the USLE is that it is easy to use.

A relatively new model for predicting soil loss is CREAMS (Knisel 1980).It is a computer nmdel tailored for field-sized plots and is capable, unlikethe USLE, to evaluate sediment yield on a storm-by-storm basis. This modelwas developed by the US Department of Agriculture in 1980. CREAMS has thecapability, in addition to its hydrology and sediment yield components, tomodel the movements of pesticides and nutrients. Soil loss at Pantex wascomputed using both the USLE and the CREAMS model. Movement of sediment intoPlaya Basin #1, which was considered to be a typical watershed in terms ofslope, land use, and type of vegetation, was computed.

.

12

A. Methodology

The Universal Soil Loss Equation (Idischmeier 1978) is

-,A=RKLSCP,

where A = computed soil loss per unit area, in tons/acre/year,R = rainfall and runoff factor,K = soil erodibility factor, which is the soil loss rate per

erosion index unit for a specified soil as measured on a uniformplot 72.6 feet long, of uniform 9% slope, continuously in cleantilled fallow,

L = slope length factor,S = slope-steepness factor,C = cover management factor, andP = support practice factor.

Each of these variables is evaluated for the particular field, throughinformation on the soil type, crop management and field practices, and fieldslope.

The CREAMS Model (Knisel 1980, Foster 1981, Lane 1981) is designed tosimulate rainfall, runoff, erosion, and movement of pesticides and nutrients.It is designed to operate on both storm-by-storm and annual basis, unlike theUSLE . For this application, only the hydrology and erosion components of themodel were used. Information from USGS topographic maps, USLE parameterinformation, and crop and precipitation data measured at the US Department ofAgriculture’s Agricultural Research Station at Bushland, Texas, were used forinput information. Guidance on parameter selection is found in the CREAMSmanual (Foster 1980).

B. Results

The soil loss rate for a wheat crop using the USLE was 0.5 - 0.7tons/acre annually. The variability comes from the choice of the rainfallrunoff factor and cover management factor.

An average soil loss rate using the CREAMS model on a wheat crop isshown in Table XII. The watershed was subdivided and the soil loss wascomputed on each subwatershed area. Each value represents the average ofyears of rainfall-runoff-erosion simulation. Soil loss rates werecomputed for native grasses using leaf area indices from a similar

. (Knight 1973).

alsoprairie

20

13

c. Discussion

There .isa great deal of similarity between the soil loss ratespredicted by both the !JSLEand CREAMS for the wheat crop. In particular, thevalues of 0.38, 0.52, and 0.39 tons/acre should be compared to the USLEvalues because these are all overland flow simulations.

The CREAMS soil loss rates for the southwest and north subwatersheds arelarger in all instances because these subbasins have an active channel compo-nent. This channel serves to move soil through and out of the subbasinfaster. There is no comparable analogy to this type of sediment movement inthe USLE.

Table XII also points out that areas with native grasses, such asbuffalo grass and blue grama, which are indigenous to the region, probablyproduce less sediment than from areas with a wheat crop. Usual farinpractices at the Pantex plant include leaving a wheat stubble residue, orplowing the residue under while the field remains unused during all ofmiddle-to-late slJmmer. This is in contrast to native grasses, which aregrowing during this period, which also happens to coincide with Amarillo’srainfall pattern (predominant precipitation period from May through August).Therefore, the native grasses are still growing during the period of greatestrunoff and sediment transport potential and would be expected to produce lesssediment yield than a plowed-but-unplanted field. This has implications ifland management practices were to be evaluated in terms of contaminanttransport. This exercise concludes that land retained in native grassesprovides less potential for lateral movement of contaminants that wouldadsorb and travel with soil particles than would land planted in a wheatcrop at the Pantex location.

v. SUMMARY AND CONCLUSIONS

Surface drainage on Pantex land and the Texas Tech University ResearchFarm is into playa basins. For the most part, drainage remains within theplant boundaries. There has been diversion of drainage from one playa basinto another.

Rainfall and the volume of runoff produced from the 6- and 24-hourstorms were investigated using historical data. The Soil ConservationService’s runoff curve number method was used to compute runoff and theresulting volume of water conveyed to the playa basins to determine theextent of flooding. The only incidence of flooding on the plant site wouldhe some structures in Basin #2 and some abandoned buildings on the Texas TechUniversity Research Farm. There may also be some flooding of offsitefarmhouses and buildings located north and west of Pantex.

Optimal culvert sizes in Zone 11 and Zone 12 to convey storm runoff fromdesign storms of recurrence intervals of 5, 10, 25, 50, and 100 years were

14

●computed using a combination of the Izzard or the Kinematic wave formulas forthe time of concentration, the Manning equation, and the Rational Formula.In Zone 11, all the culverts considered were adequately sized to carry the100-year flood event under nonsubmerged inlet conditions. In Zone 12, allbut three culverts will carry the storm water runoff associated with the 100-year flood under nonsubmerged conditions.

Soil loss was computed over Drainage Basin #4 using the Universal SoilLoss Equation and the CREAMS model. Calculations were made both for a wheatcrop and for native grasses. The CREAMS model predicted an average soil losson a field planted in wheat between 0.3 and 1.0 ton /acre annually foroverland flow, which agrees well with the amount predicted by the UniversalSoil Loss Equation. The amount of soil loss effectively doubles Men runoffis combined overland-channel flow.

Soil loss was also computed using the CREAMS model on fields of nativegrasses. Soil loss rates are around 0.2 to 0.6 tons/acre annually, lowerthan for a wheat crop.

Therefore, at the Pantex location, land retained in native grassesprovides less potential for lateral movement of contaminants that wouldadsorb and travel with soil particles than would land planted in a wheatcrop.

ACKNOWLEDGMENTS

The authors wish to thank Howard Kirkpatrick of Mason and Hanger-SilasMason Company, Inc., for his field assistance; and Ron Davis and O. i?.Jonesof the US Department ofLaboratory at Bushland,

REFERENCES

Chow 1959: V. T. chow,

1959) .

Agriculture’s Conservation and Production ResearchTexas, for their generous sharing of data.

Open Channel Hydraulics (McGraw-Hill, New York,

Foster 1980: G. R. Foster, L. J. Lane, and J. il. Nowlin, “A Model toEstimate Sediment Yield from Field Sized Areas: Selection of ParameterValues; in “CREAMS - A Field Scale Model for Chemicals, Runoff, andErosion from Agricultural Management Systems, Vol. 11 User Manual,” USDep. Agric., Conservation Research Report No. 26 (1980).

.Foster 1981: G. R. Foster, L. J. Lane, J. D. Nowlin, J. M. Laflen, and R. A.

Young, “Estimating Erosion and Sediment Yield on Field-Sized Areas;Trans. Am. Sot. of Agric. Eng. 24, No. 5, 1253-1262 (1981).—

Jacquot 1962: L. L. Jacquot, “Soil Survey of Carson County, Texas, ” US Dep.Agric. Series 1959, No. 10 (July 1962).

Knight 1973: D. H. Knight, “Leaf Area Dynamics of a Shortgrass Prairie inColorado,” Ecology 54, No. 4, 891-896 (1973).—

Knisel 1980: W. G. Knisel, Jr., cd., “CREAMS: A Field-Scale Model forChemicals, Runoff, and Erosion from Agricultural Management Systems,” USDep. Agric., Conservation Research Report No. 26 (1980).

Lane 1981: L.Burial ofLaboratory

Laseter 1982:

J. Lane and J. W. Nyhan, “Cover Integrity in Shallow Land,OW Level Wastes: Hydrology and Erosion,” Los AlarrIosNationadocument LA-UR 81-3260 (1981).

William A. Laseter, “Environmental Monitoring Report forPantex Plant Covering 1981,” Mason and Hanger-Silas Mason Co., Inc.,Amarillo, Texas (April 1982).

Linsley 1972: R. K. Linsley and J. B. Franzini, Water-Resources Engineering_(McGraw-Hi11 Book Company, New York, 1972).

Purtymun 1982A: W.D. Purtymun, N.M. Becker, and Max Maes,’’Supplementary Documen-tation for an Environmental Impact Statement Regarding the Pantex Plant:Geohydrologic Investigations,” Los Alamos National Laboratory reportLA-9445-PNTX-H (1982).

Purtymun 1982B: William D. Purtymun and Naomi M. Becker, “Supplementary Documen-tation for an Environmental Impact Statement Regarding the Pantex Plant:Geohydrology,” Los Alamos National Laboratory report LA-9445-PNTX-I (1982).

Ragan 1972: Robert M. Ragan and J. Obiukwufor Times of Concentration,” Am. Sot. C1765-1771 (October 1972).

Soil Conservation Service 1972: Soil Consel

Duru, “Kinematic Wave Nomographv. Eng. J. Hydraul. Div. HY 10,

vation Service, US Dep. Agric.,“SCS National Engineering Handbook, Section 4: Hydrology” (August 1972).

US Department of Commerce 1961: US Dep. Commerce Weather Bur.,“Technical Paper No. 40 Rainfall Frequency Atlas of the United States forDurations from 30 Minutes to%?4 Hours and Return Periods from 1 to 100Years” (May 1961).

Viessman 1977: W. Viessman, Jr., J. W. Knapp, G. L. Lewis, and T. E.Harbaugh, Introduction to Hydrology [Harper & Row, New York, 1977).

●

16

Wischmeier 1978: W. H. Wischmeier and D. D. Smith, “Predicting Rainfall.Erosion Losses - a Guide to Conservation Planning,” US Dep. Agric.,Agriculture Handbook No. 537 (1978).

.

Zeller 1979: Michael E. Zeller, “Hydrology Manual for Engineering Design andFlood Plain Management within Pima County, Arizona, for the Prediction ofPeak Discharges from Surface Runoff on Small Semiarid Watersheds for 2-Year through 100-Year Flood Recurrence Intervals,” Pima County Dep.Transportation and Flood Control Dist., Tucson, Arizona (September 1979).

\

.

18

Ii----4

V)

LOJ

>.-.m

RAINFALL(P) IN INCHES

Fig. 3. Graphic solution of the runoff equation.

PLAYA BASIN

CONTOURS

4 4

CONTOUR INTERVAL 5FEET

PLAN VIEW

1-

; 15

1~ :

ADDITIONAL VOLUMECONTAINED WITHIN 15

~ [0 SUCCESSIVE CONTOUR 10zQ5 5

G o 02d

CROSS SECTION VIEW

Fig. 4. Playa basin volume.

20

.

I

03.0

27

N

.

c

ul-1aou)

-QcovLA.mL

c

.

22

6-HOU

RECURRENCE INTERVALI YEARAMC II

RECURRENCE INTERVAL50 YEARSAMC II

o

STORM

RECURRENCE INTERVALI o YEARSAMC II

RECURRENCE INTERVALIOOYEARS

AMC III

7000Feet

o 2Kilometers

SCALE

Fig. 5.(cent)

23

24-HOU’

RECURRENCEINTERVALI YEAR

AMC II

\

RECURRENCEINTERVAI50 YEARSAMC II

o

“OR hAv! .1. !

RECURRENCEINTERVAL10 YEARSAMC II

RECURRENCEINTERVAL100 YEARS

AMC III

7000 Feet

o 2Kilometers

SCALE

Fig. 5.(cent)

BASIN No.36-HOUR STORM

RECURRENCEINTERVALk I YEAR

o 7000 Feet

o 2Kllometers

SCALE

L

Fig. 5.(cent)

25

BASIN No,324+iOURSTORM

RECURRENCE INTERVALI YEAR

\


(RECURRENCE INTERVAL

100 YEARSAMC H

o 7000 Feet

o 2Kilometers

SCALE .

Fig. 5.(cent)

BASIN No.46 -HOUR STORM

RECURRENCEINTERVALI YEARS


IAMCIt

RECURRENCE INTERVAL10 YEARS

RECURRENCEINTERVA1100 YEARSAMC III

o 7000 Feet

o 2Kilometers

SCALE

Fig. 5.(cent)

27

BASIN No.424-HOUR STORM

RECURRENCElNTERbI YEAR

AMC II

\

RECURRENCEINTER50 YEARS


AMC 13

I


~

o 7000 Feet

o 2Kilometers.

.SCALE

Fig. 5.(cent)

BASIN No.56- HOUR STORM

RECURRENCE INTERVAL

I YEAR

AMC II


AMC II

I

o

RECURRENCE INTERVAL

10 YEARS

AMC IL

--7000 Feet

o 2Kilometers

SCALE

Fig. 5.(cent)

29

BASIN NO.524-HOUR STORM


AMC II



AMC IT-

~

0 7000 Feet

o 2Kilometers.

SCALE

Fig. 5.(cent)

30

.

.

BASIN No.66-HOUR “Trim”

R

( al UI-IIW

o 7000 Feel-~2Kllomelers

‘~SCALE

Fig. 5.(cent)

9A.UIU IL-1 ! .“”!

R

.

Uniw


AMC II

o 7000 Feet

.

0 2Kllometmrs

sCALE

Fig. 5.(cent)

32

t.

.

6-HOUI

RECURRENCE INTERVALI YEARAMC II

, “,,,”,

o 7000 Feet

o 2Kllometers

SCALE

Fig. 5.(cent)

.

33

24-HOUI

RECURRENCE INTERVALI YEARAMC 11

, “,,,.,

0 7000 Feat

o 2Kilometers

SCALE

Fig. 5.(cent)

.

.

.

.

BASIN No. 96-HOUP c~fiD~J


IAMC11

7‘ECUR’::’’’’’ERVAL

,, .J, ”,\,vl

RVAL

RVAL

o 7000 Feet,

0 2Kilometers

SCALE

Fig. 5. (cent)

.

35

BASIN No. 924,.HOu~ CTfIWh.4

~ ‘ECUR’RRNTERVALI “MC11

ERVAL

\ .J B “&\u. #

RVAL

‘AL

o 7000 Feel

2Kllometcrs‘~

SCALE

.

Fig. 5.(cent)

.

36

BASIN NO.106-HOURSTORM

.




RECURRENCE INTERVAL

n 7000 Feet&o 2Kllometers

SCALE

Fig. 5.(cent)

.

37

BASIN NO.1024-HOURSTORM

RECURRENCE INTERVALI YEARS


RECURRENCE INTERVAL

IO YEARS

RECURRENCE INTERVAL

----- .0 Iuuu reer

o 2Kliometers

SCALE

.

.

Fig. 5.(cent)

38

.

!FLOODING IN BASIN NK).2

@

FM 79?I

EO AREA

FLOOOING IN BASIN NO. B

)

I.—

Fig. 6. Flooding of buildings due to the 6- and 24-hour storms.

.

39

.

AI

J\//J

L-

.m

laJcs.3u+fuu0-1.0-l.1-IL

40

.

.

6-

5-

4-

3-

2-

1

00

~ 100 year storm

xx 50 year storm

~ 25 year storm

AA 10 year storm

~ 5 yeor storm

Ocl 1 year storm4

>

?:c

o

. .. . ... .... . . .

I I I I I

5 10 15 20 2“5

Duration (hrs)

“ref. U.S. Dept. of Commerce, Technicol Poper No.40, “RainfoilFrequency Atlos of the U.S. for Durotions from 30 Minutesto 24 Hours ond Periods from 1 to 100 Years,” 1961.

Fig. 8. Intensity-duration-frequency curves for Pantex.

47

.

N~

‘+- 0b

.N‘3vco.-

.m

:-0

.

.

SCALEo 5000 ft

o I500m1 #

Fig. 10. Ditch system to Playa Basin #1.

.

43

.

.l-lt-ls

.l-l.m

,.

.

uJ$01-

1-

0zIii1

-0z

.l-ldw

:

&L..-

50

N

----1

-------1

m

s

IIIIII—

----——

-——

——

-e

IIIIIIII

tivaJccov

(E)

ill

(bI

i-La

III1

IIIIIIII

ki\\\\\\\\\

.N

mT

.cl

/’L

.5.‘\

03-.\

\w

“\z

\oN

\\‘..,.%

q?

IIJh~-- 4‘-

-.—--

——

__—

-

/“

/

.

45

TABLE I

RAINFALLINTENSITIES FOR AMARILLO, TEXAS

6-Hour Storm .—

RecurrenceInterval (yr) Amount (in.)

5 2.910 3.425 4.050 4.!5100 5.0

Basin No.

12345678910

24-Hour Storm.—

RecurrenceInterval (yr) Amount (in.)

5 3.710 4.525 5.350 5.8

100 6.5

TABLE II

CURVE NUMBERS FOR PANTEX BASINS

Area CN CN(Acre) AMC II AMC I

3441118224932577150322001186378027201422

86868787878786878787

72727373737372737373

CNAMC 111

9494959595

9594959595

46

Frequency

Basin No. 1

5 yr10 yr25 yr50 yr100 yr

Basin No. 2

5 yr10 yr25 yr50 yr

100 yr

Basin No. 3

5 yr10 yr25 yr50 yr

100 yr

Basin No. 4

5 yr10 y-r25 yr50 yr

100 yr

TABLE III

RUNOFF VOLUMES INTO PLAYA BASINS

6-Hour Storm

Rainfall PIaya(in.) Area (Acre)

Area = 3326 Acre

2.93.44.04.55.0

Area = 1119 Acre

2.93.44.04.55.0

Area = 2411 Acre

2.93.44.04.55.0

Area = 2488 Acre

2.93.44.04.55.0

115

63

82

89

Runoff Volume (Acre-ft)AMC II

471 “587745875

1004

164204259303348

341425540634727

353440558655752

AMC I

236337440542658

85116156191231

170234319392476

177243330407493

AMC III

665809957

11101254

230279333378432

482586700794908

498606724821939

*

.

47

Frequency

Basin No. 5

5 yr10 yr25 yr!50yr

100 yr

Basin No. 6

5 y?-10 yr25 yr50 yr

100 y?-

Basin No. 7

5 yr10 yr25 yr50 yr

100 yr

Basin No. 8

5 yr10 yr25 yr50 y-r

100 yr

Basin No. 9

5yl-10 yr25 yr50 yr

100 yl-

48

TABLE III (cent).

6-Hour Storm (cent)

Rainfall PIaya Runoff Volume (Acre-ft) -(in.) Area (Acre)

Area = 1392 Acre

2.9 1113.44.04.55.0

Area = 2043 Acre

2.9 1573.44.04.5!5.0

Area = 1186 Acre

2.9 03.44.04.55.0

Area = 3653 Acre

2.9 1273.44.04.55.0

Area = 2596 Acre

2.9 1243.44.04.55.0

AMC II AMC I AMC”III

212263333390446

310385486570653

158198252296341

518645817961

1103

376468593696798

114153205250301

166223299365440

74104143178217

259356484596723

192262355436528

294356426482551

430521623706806

227277331376430

731888106212041377

528641766 “869993 -

TABLE 111 (cent).

6-Hour Storm (cent)

.

FrequencyRainfall(in.)

P1aya Runoff Volume (Acre-ft)Area (Acre) AMC II AMC I AMC III— ,—.

Basin No. 10 Area = 1314 Acre


2.9 108 201 108 2783.4 250 146 3374.0 315 195 4034.5 369 238 4575.0 423 286 521

24-Hour Storm



3.7 115 673 396 8954.!5 875 542 10965.3 1090 716 13265.8 1234 832 14696.5 1420 1005 1670



3.7 634.55.35.86.5

234303378427491

141191252292351

308378457506575

Basin NCJ.3 Area = 2411 Acre


3.7 824.55.35.86.5

4876347908941029

286392518602728

648794960

10641210


. 5 yr10 yr25 yr50 yr100 yr

3.7 894.55.35.86.5

504655817924

1064

297407537624753

670821993

11001251

49

TABLE III (cent).

24-Hour Storm (cent)

PIaya Runoff Volume (Acre-ft) -Area (Acre) AMC II AMCI AMC III

Rainfall(in.)Frequency

Area = 1392 AcreBasin No. 5

301390484547629

185251328379455

394483583646733

3.7 1114.55.35.86.5

5 yr10 yr25 yr50 yr

100 yr


3.7 1574.55.35.86.5

440570708799919

270365478553664

5767068529441072



3.7 04.55.35.86.5

227296371420484

128178237277336

306376455504573



9831204145616141834

3.7 1274.55.35.86.5

739961787

13551560

4355961198914

1104



319436574666803

709867 “

10501163 -1322

5 yr10 yr25 yr50 yr

100 yr

3.7 1244.55.35.86.5

5366968669791127

50

TABLE III (cent)

Frequency

Basin No. 10


Rainfall(in.)

24-Hour Storm (cent)

PIaya Runoff Volume (Acre-ft)Area (Acre) AMC II AMC I AMC III

Area = 1314 Acre

3.7 108 285 176 3734.5 369 238 4575.3 458 310 5515.8 518 359 6116.5 595 431 694

TABLE IV

VOLUMES ENCLOSED BY CONTOURS IN PLAYA BASINS

Contour

352035253530

Volume (acre-ft)

361.251252.2200.

Basin #1

Basin #2

Basin #3

35603565

188.75710.

352035253530

266.25877.51362.5

3515352035253530

267.5767.5

1120.1635.

Basin #4

Basin #5

Basin #6

Basin #8

35053510

356.251337.5

34903495

480.1440.

350035053510

42B.751355.2035.

35103520

722.52900.

Basin #9

Basin #10 35003505

327.5932.5

TABLE V

RAINFALL INTENSITY AS A FUNCTION OF RAINFALL DURATION

Recurrence Interval Power Equation

.@@

5102550

100

i=i=i=i=i=

44.15054.16661.17477.005B2 .389

~ -0.773+ ‘0.776; -0.771t -0.789t ‘0.7B3

where i ❑ rainfall intensity in inches/hour and t = duration inminutes.

52

TABLE VIPEAK DISCHARGE COMPUTATIONS FLM ZONE 12

Area AreaDrained Drainedby (ftz) (acres)

MaximumF1OW

Length(ft)

6605506101410410240600240230910

700210

5004904303201805501030380580340600450

350500110250

300320330

1170440700

1040

450

20040U

RunoffCoeff.

c

0.60.30.350.4

:::0.70.650.60.35

0.60.6

0.60.650.30.30.40.40.50.60.50.40.60.4

0.60.50.50.5

0.70.30.30.30.40.2

0.65

0.5

0.50.55

4w-.— 44——-4J%-.—2.140.650.882.835.513.153.702.121.722.12

7.460.80

3.633.39

0:27 ;:;;0.54 0.64

4.194.843.662.731.505.932.68

1.69

0:51 %0.67

CulvertLocation

Slope

u

Manningn

0.1150.120.120.1250.120.1150.1150.120.120.12

0.1250.12

0.1150.1150.120.120.120.1350.120.1150.120.1150.1150.12

0.1150.1150.1150.11

0.1150.120.120.120.120.13

0.14

0.12

0.1150.12

97 07873 44985 230

407 315187 134

72 850126 298

44 76239 570

268 737

373 36917 372

137 414112 487

26 61728 12222 597

338059397 531114 916152 256

78 641253 255174 720

50 17087 9921028419 902

37 87379 57350 320

146 66567 59282 535

159 545

79 648

20833161 708

2.231.691.969.354.301.672.901,030.916.17

8.570.40

3.152.580.610.650.527.769.132.643.501.815.814.01

1.152,020.240,46

0.871.831.163.371,551,89

3.66

1.83

0.483.71

73.397.097.1

192.850.330.561.730.230.5

137.4

12-112-212-312-412-512-612-712-812-912-1012-1112-1212-1312-1412-1512-1612-1712-1812-1912-2012-2112-2212-2312-2412-2512-26

1.601.281.280.762.143.151.823.173.150.98

1.453.35

83.028.1

1.922.021.521.853.101.351.062.311.562.081.701.67

57.654.078.460.631.191.0

124.545.475.652.167.569.0

8639

1.412.59

0< 3

12-2712-2812-2912-3012-3112-3212-3312-3412-3512-3612-3712-3812-3912-4012-4112-4212-4312-4412-4512-46lZ-47;;-;;

12:6APonded AIConst. E12-28/29I = Izzalculverts

42.3 2.441.774.902.91

4.27

33.8;6 60.688 62.3

187.0

2=9 l%;

2.901.851.810.771.700.86

1.770:77 1.010.48 0.63

0.781.05

0.23 0.33

1:411.38

0:60

123.3 1.07

1.85

2.54

60.6 1.69

28.951.8

3.282.09

0.794.26

-eaof

.dl~for

Formula; K = Kinematic Wave Formula; Crhtsichinformation is not presented were

= 0.025; Oischarge computed by the Rational Formula Q = CiA. Thoseeither missing, fi11ed, crushed, or combined with another CU1vert.

.

53

TABLE VI (cent)

CulvertLocation

12-112-212-312-412-512-612-712-812-912-1012-1112-1212-1312-1412-1512-1612-1712-1812-1912-2012-2112-2212-2312-2412-2512-2612-2712-2812-2912-3012-3112-3212-3312-3412-3512-3612-3712-3a12-3912-4012-4112-4212-4312-4412-4512-4612-4712-4812-4912-6A

T 10-yr

-+%-——

65.186.186.2

171.244.627.054.826.827.0

122.0

73.625.0

51.147.969.553.827.6

lR40.367.146.259.961.2

37.556.815.229.9

30.053.855.2

166.060.0

144.0

109.5

53.8

Ponded Area - 25.6Const. E of 45.912-28129

i lo-yr

*——

2.121.711.711.002.844.202.424.234.201.30

1.934.46

2.562.692.022.464.131.791.413.082.072.762.262.22

3.252.366.543.88

3.872.462.411.022.261.14

1.42

2.46

4.372.78

4%4=R--—— ——2.840.861.173.747.334.204.922.832.292.81

9.911.07

4.844.510.370.480.865.576.424.883.632.007.883.57

2.242.380.780.89

2.361.350.841.041.400.43

3.37

2.25

1.055.67

1 = Izzard’s FormulaK = Kinematic Uave FormulaOischarges computed by the Rational Formula A = CiA

Cr = 0.025

60.379.879.8158.441.425.150.824.825.1113.0

68.223.2

47.444.564.449.925.674.8102.337.462.242.955.556.8

34.852.714.227.8

27.849.951.2153.655.7133.3

i 25-yr

--++.—

.

2.592.092.091.233.465.102.965.145.101.60

2.365.42

3.123.282.46

:::2.201.723.752.533.372.762.72

3.962.887.924.71

4.71

;::1.262.761.41

+%--——

3.471.061.434.618.945.116.013.442.783.45

12.121.30

5.905.500.450.591.046.827.885.944.432.449.644.36

2.732.910.951.08

2.871.651.021.281.710.53

101.4 - 1.74 - 4.14

49.9 - 3.00 - 2.75

23.8 - 5.31 - 1.2842.6 - 3.39 - 6.92

.

54

*TABLE VI (cent)

CulvertLocation

12-112-212-312-412-512-612-712-812-912-1012-1112-1212-1312-1412-1512-1612-1712-1812-1912-2012-2112-2212-2312-2412-2512-2612-2712-2812-2912-3012-3112-3212-3312-3412-3512-3612-3712-3812-3912-4012-4112-4212-4312-4412-4512-4612-4712-4812-4912-6APonded AreaConst. E of12-28f29

--’P+.— *—— ---#k——T 50-yr i 50-yr Q 50-yr - ‘ -- i 1OO-W Q 1OO-N

+@K-.—

55.073.073.0

145.937.622.746.222.422.7

103.7

62.320.9

43.140.458.845.423.268.493.833.956.739.050.651.7

31.548.012.725.1

25.245.446.6

141.450.7

122.5

92.9

45.4

21.538.7

3.262.612.611.514.406.563.746.616.561.98

2.966.99

3.954.163.093.806.452.752.144.783.184.283.483.42

5.063.63

10.356.05

6.043.803.721.553.481.73

2.16

3.79

6.854.30

4.361.321.795,65

11.366.587.594.433.584.27

15.201.68

7.476.970.570.741.348.529.777.575.573.10

12.145.49

3.493.671.241.39

3.682.081.291.562.160.66

5.13

3.47

1.648.78

I = Izzard’s FormulaK = Kinematic Uave FormulaOischarges computed by the Rational Formula Q = CiA

Cr = 0.025

T 100-yr

++——

52.269.169.2

137.935.721.643.921.421.698.1

59.119.9

40.938.455.843.122.064.888.832.253.837.048.049.1

30.045.512.123.9

23.943.144.2

133.7

1%:

88.0

43.1

20.436.8

4%!-- -

3.732.992.991.745.017.444.277.507.442.27

3.387.92

4.504.743.544.337.323.142.465.443.644.883.983.91

5.754.14

11.686.87

6.854.334.241.783.971.99

2.48

4.33

7.764.90

4.981.522.056.51

12.937.468.665.024.064.91

17.381.90

8.517.940.650.841.529.76

11.218.616.373.53

13.866.27

3.974.191.401.58

4.172.381.481.802.460.75

5.89

3.96

1.8610.00

55

TABLE VII

SUMMED DESIGN DISCHARGES FOR ZONE 12 - RATIONAL METHOD

CulvertLocation

12-112-212-312-412-512-612-712-812-912-1012-1112-1212-1312-1412-1512-1612-1712-1812-1912-2012-2112-2212-2312-2412-2512-2612-2712-2812-2912-3012-3112-3212-3312-3412-3512-3612-37

Q 5-yr(Cfs)

2.142.793.676.505.518.66

12.362.123.84

20.98

7.468.26

11.9015.2915.56

0.360.64

22.005.433.666.397.89

13.8316.51

1.691.790.59

17.18

1.772.780.630.785.89

Q 10-yr(Cfs)

2.843.704.878.627.3311.5416.462.835.1227.89

9.9110.98

15.8220.3220.690.480.8629.237.204.888.5010.5018.3921.96

2.242.380.78

22.85

2.363.710.841.047.83

Q 25-yr(Cfs)

3.474.535.9610.578.9414.0520.063.446.2234.08

12.1213.43

19.3324.8325.280.591.04

35.738.835.9410.3812.8222.4526.81

2.732.910.9527.90

2.874.521.021.289.56

Q 50-yr(Cfs)

4.365.697.48

13.1211.3617.9325.524.438.0142.92

15.2016.87

24.3431.3131.880.741.34

44.9711.017.5713.1416.2428.3833.87

3.493.671.24

35.26

3.685.761.291.56

12.09

Q 100-yr(Cfs)

4.986.508.5515.0612.9320.3929.055.029.08

49.01

17.3819.28

27.8035.7436.390.841.52

51.3612.618.6114.9818.5132;3738.64

3.974.191.40

40.22

4.176.551.481.80

13.79

.

.

.

56

TABLE VII (cent)

Culvert. Location

Q 5-yr(Cfs)

Q 10-yr Q 25-yr(Cfs) (Cfs)

Q 50-yr(Cfs)

Q 100-yr(Cfs)

12-3812-3912-4012-4112-4212-4312-4412-4512-4612-4712-4812-4912-6APondedAreaConst. Eof 12-28/29

6.22 8.26 1(3.09 12.75 14.54

5.13 5.892.54 3.37 4.14

3.471.69 2.25 2.75 3.96

0.79 1.05 1.28 1.64 1.86

4.26 5.67 6.92 8.78 10.00

57

colt-to

c?#.A~

%‘%%%-

5sU

uum

.s-

--.,-!Y-”

.:+l!w

.-uuu\-u

uO

.um

a.a

aam

ma

..-?--.$--

-.,-----

.-U

rn----

-u-----

-mm

!-.-c--*

--LLl=

-ww

ww

eul

w

x

●

58

..-f

.

59

I

TABLE IX

PEN DISCHARGE COMPUTATIONS FCR ZONE 11 -1

CulvertLocation

11-111-211-311-411-511-611-711-811-911-1011-1111-1211-1311-1411-1511-1611-1711-1811-1911-2011-2111-2211-2311-2411-2511-2611-2711-2811-2911-3011-3111-3211-3311-3411-3511-3611-3711-3811-3911-4011-4111-4211-4311-44

AreaDrained(ftq

40 633

59 008

10 57712 878

1234715 75U

701 715257 066

854021

26 3417 3973 615

38 5577 1967 3306 2594 25121 75695 75823094130 08111 146

1900325 705

314 11651 53545 68759 242

306 125147 536

AreaDrained

-

0.93

1.35

0.240.302.830.13

16.115.90

19.61

0.600.170.080.890.170.170.140.100.502.200.532.990.26

0.440.59

7.211.181.051.367.033.39

Slope@w..

0.003

0.003

0.0030.(030.0030.002

0.0030.003

0.001

0.0030.0030.0030.0030.003o.cm30.0030.0030.D030.0060.0060.0060.006

0.0060.006

0.0060.0030.0030.0030.0010.003

MaximumF1OW

L!2w!lw

270

310

160120400

70

1175600

1560

320150

90210100

1::

1%700270850130

160250

1020450325280

1000600

RunoffCoeff.

c

0.3

0.2

:::0.250.8

0.20.2

0.25

0.70.80.70.30.350.250.50.70.40.4

::;50.8

0.70.25

0.25

::;0.450.250.40

Manningn

0.17

0.09

0.100.110.130.03

0.180.18

0.20

D.090.050.090.100.080.090.100.050.100.150.170.150.03

0.070.13

0.170.130.090.120.190.06

4L@w@T-—— —— ——112

215

39

lx15

538339

1024

i69446

;:

;;

3;7

;5

;6755

71

58

21

;3

338188

670

29

1:36141714

2:91

1:3

943

18565

::43649

1.15 1.64 0.32 0.46

0.69 1.91 0.19 0.52

2.61 4.18 0.31 0.501.77 3.79 0.16 0.340.77 1.39 0.54 0.985.39 17.63 0.56 1.83

0.34 0.49 1.10 1.580.49 0.77 0.58 0.91

0.21 0.29 1.03 1.42

3.28 - 1.388.59

5;08 7.68 0:28 :i1.31 2.77 0.35 0.742.30 5.68 0.14 0.341.70 4.85 0.07 0.213.36 5.74 0.24 0.405.40 12.34 0.38 0.862.00 3.64 0.40 0.73

1.35 - 1.192.36 - 0.50

0:51 0.96 0.38 0.7216.82 - 3.50

2.401:43 R 0:21 0.36

0.78 - 1.411.75 - 1.03

1:74 ;:;; 1:06 i%0.26 0.40 0.46 0.71

2.20 - 2.98

I = Izzard’s FormulaK = Kfnmat ic Have FormulaCr = 0.030

Note: Those culverts for which information is not presented were either missing, filled, crushed, orcombined with another CU1vert.

TABLE IX (cent)

.CulvertLocatfon

11-111-211-311-411-511-611-711-811-911-1011-1111-1211-1311-1411-1511-1611-1711-1811-1911-2011-2111-2211-2311-2411-2511-2611-2711-2811-2911-3011-3111-3211-3311-3411-3511-3611-3711-3811-3911-4011-4111-4211-4311-44

-YI--.—86

166

i9145

2i2

795

;23552

5i5

63

52

;:783

300167

596

267

3;131512

2;81

1;:3

838

1645832

~43

1 = Izzard’s FormulaK = Kinematic Wave FormulaCr = 0.030

i lo-yr

++——

1.71 2.18

1.03 2.54

2:63 ::::1.14 1.85

23.68

0.650:72 1.02

0.30 0.38

4.3711.5010.29

1:95 3.703.43 7.602.53 6.47

7.6716.564.851.793.141.27

22.60

10.443.20

1.042.333.723.23

0.39 0.532.92

+%-——

0.48 0.61

0.28 0.69

0.670:24 0.460.81 1.31

2.46

0~85 ;:%

1.47 1.87

1.841.560.58

0.52 0.990.20 0.450.11 0.28

0.541.160.971.580.660.954.70

3.220.47

1.871.371.95

0:69 ::;:3.96

w-r——58

48

::723

277155

550

247

3;121412

2:75

1?:3

3:

1525329

3%40

--F%——2.66

1.39 3.10

3:52 g:ij2.26

28.37

0.801.26

0.47

5.3113.8612.414.50

4.57 9.183.38 7.84

9.2819.895.892.203.821.56

27.08

12.603.90

1.272.844.523.930.663.56

-Yw-——0.74

0.38 0.84

0:32 )!;1.602.95

2.58- 1.48

2.31

2.231.890.701.20

0:27 0.550.14 0.33

0.651.391.181.930.811.175.63

3.880.58

2.301.682.382.411.164.83

Note: Those culverts for which information is not presented were either missing, filled, crushed, orcombined with another CU1vert.

.

-

.

TABLE IX (cent)

CulvertLocat1on

11-111-211-311-411-511-611-711-811-911-1011-1111-1211-1311-1411-1511-1611-1711-1811-1911-2011-2111-2211-2311-2411-2511-2611-2711-2811-2911-3011-3111-3211-3311-3411-3511-3611-3711-3811-3911-4011-4111-4211-4311-44

T 50-yr

-+%——

53

43

161866

2

257142

513

216

2;101310

1!68

1:;3

732

1404927

3:;36

1 = Izzard’s Formula

4=iJ-——3.35

3.93

8.807.942.83

38.69

0.971.54

0.56

6.8418.4616.46

5.7612.0610.2412.1826.81

7.612.754.871.93

36.87

16.714.98

1.563.595.805.020.794.53

-Y%- -Y&J-PwY%-.— ——.— __0.94

1.06

1.060.722.004.02

3.121.82

2.74

2.872.510.921.540.72

0.20 0.440.851.881.522.421.031.447.67

5.150.73

2.822.123.043.071.396.14

50

41

:62

2

242135

482

206

2:10

;:4

:;

1:;2

3:

132

;:30

31334

3.83

4.48

9.948.993.24

43.02

1.121.77

0.65

7.7620.6918.47

6.5413.5811.5513.7229.92

8.623.145.542.22

41.02

18.765.66

1.804.106.585.710.925.16

1.07

1.21

1.190.812.294.47

3.612.09

3.20

3.262.811.031.750.810.490.962.101.722.771.171.668.53

5.780.84

3.242.423.463.491.616.99

K = Kinematic Wave FormulaCr = 0.030

.

.

...

zZ

lz.-

.,-.-0-

LI+2L

u0

63

TABLE XI

SUMMED DESIGN DISCHARGES FOR ZONE 11 - RATIONAL METHOD

CulvertLocation

11-111-211-311-411-511-611-711-811-911-1011-1111-1211-1311-1411-1511-1611-1711-1811-1911-2011-2111-2211-2311-2411-2511-2611-2711-2B11-2911-3011-3111-3211-3311-3411-3511-3611-3711-3811-3911-4011-4111-4211-4311-44

twr

0.46

0.52

0.840.552.761.83

6.347.25

3.61

1.381.170.430.740.340.210.920.860.734.680.504.223.50

2.400.36

3.812.871.461.480.712.98

Q(;li;

0.61

0.69

1.120.733.692.46

8.459.66

4.78

1.841.560.580.990.450.281.221,160.976.240.665.654.70

3.220.47

5.OB3.841.951.980.943.96

Q(:2ir

0.74

0.84

1.360.884.482.95

10.2811.76

5.88

2.231.890.701.200.550.331.491.391.187.590.816.805.63

3.B80.58

6.184.632.382.411.164.B3

Q 50-yr(Cfs)

0.94

1.06

1.771,155.794.02

13.2215.04

7.20

2.872.510.921.540.720.441.911.881.529.731.039.127.67

5.150.73

7.966.143.043.071.396.14

Q 100-yr(Cfs)

1.i7

1.21

2.001.306.554.47

14.9917.08

8.30

3.262.811.031.750.810.492.172.101.72

11.041.17

10.198.53

5.780.B4

9.026.893.463.491.616.99

.

.

.

64

TABLE XII

SOIL LOSS RATES ON PLAYA BASIN #1(Tons/Acre Annual ly)

SubwatershedBasin East West

Wheat crop 0.38 0.52

Native grasses 0.21 0.24

Southwest

1.05

0.48

Southeast North

0.39 1.00

0.33 0.62

65

Pace Range

!w2sPlice Co&

00102s02605005I07s076.IM101.12s126.1S0

AO1

A03

AM

A05

A06

A07

.Ptimed in fhe Uniwd SIaIes O( A-

.,Avsilabk fmm

Nedond Techmcai Information Scev&

US Dfptrmwnt of Commerce

S26S Pm Royal Road

SPringlleld. VA 22161

Pace Range

1s[.17s

176-200

10 I.12S

126-2s0

2S ! 27S

276.3W

Microlllhe [AOI)

NTIS

Price Code

AOS

AW

A 10

All

A12

A13

NTIS

Page Rsnsc MU Code

301.325 A 14

326.1:0 AIS

351.373 A16

376 4(X A17

401.425 Ale4:6.450 Ai9

NTIS

Page Range Price Cc&

43 I 47s A20

476.300 A21

sol 52s A22

526.530 A22

551.515 A24

576.600 A2S

601 up” AW

“Contacl NTIS b ~ price quote.

los alamos national laboratory *;~~~ ~[a~~~ … · culvert sizes in zones 11 and 12 were...

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