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APA2982
FEDERAL ENERGY"REOULATORY COMMI8SION PROJECT Ho.711. SUSITNA HYDROELECTRIC PROJECT ~==Alaska Power Authority ==::::::!..I EFFECTS OF THE PROPOSED PROJECT ON SUSPENDED SEDIMENT CONCENTRATION FINAL REPORT OECEMBER 1885 DOCUMENT No.2882 [}{]b\Iffi~~=~lID~@©@ SUSITNA JOINT VENTURE I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I SUSITNA HYDROELECTRIC PROJECT EPPECTS OP THE PROPOSED PROJECT ON SUSPENDED SEDIMENT CONCENTRATION Report by Harza-Ebasco Susiena Joint Venture Prepared for Alaska Power Authority Final Report Decembe r 1985 Docu-ent No.2982 Sudt~rUe No.".2.1 I I I I I I I I I I I I I I I I I I I NOTICE ANY QUESTIONS OR COMMENTS CONCERNING THIS REPORT SHOULD BE DIRECTED TO THE ALASKA POWER AUTHORITY SUSITNA PROJECT OFFICE TABLE OF CONTENTS 5.1 DATA SOURCE LIST OF EIHIBITS 2 .0 lAC'lGROURD 3 6 6 9 9 6 6 4 5 " 15 10 13 14 10 10 iii PAGE Suspended Sediment Concentration a,e Watana Res:rvoir Outlet River Water Temperatures Suspended Sediment Concentration between Wacana and the Chulitna Confluence Suspended Sediment Concentration ~etween the Chulitna Confluence and Sunsh'ine i At Selected Locations Suspended Sediment Entering Wataoa Reservoir 5.5.4 5.2.1 5.2.2 5.5.1 5.5.2 5.5.3 5.4 SEDIMENT TRANSPORT DURING FREEZE-UP 5.5 PROJECt EFFECT 5.2 CHARACTERISTICS OF SUSPENDED SEDlHE~ 5.3 EFFECTS OF ICE COVER ON SEDIMENT TRANSPORT LIST OF TABLES unRENCES SECTION/TITLE EXHIBITS 1 .0 SUMMARY 5.0 SUSPENDED SEDIMENT rULES 3.0 SCOPE OF THE STUDY 4.0 SETTIIG I I I I I I I I I I I I I I I I I I I •••Number ••2 3•4 I 5 •6 7 I ••••••• 1 ••• LIST or TABLES Title Suspended Sediment Samples Collected at USGS Stream Caging Stations Suspended Sedi.ent Concentrations Esti••ted Honthly Suspended Sediment Trau.port at the Selected Sites on the Susien_River Particle Size Distribution of Suspended Sediment Suspended Sedi.ent Concentrations,Wataoa Operation, Stale I Suspended Sediment Concentrations,Wat.ae-Devil Canyon Operation,Stage II Suspended Sediment Concentrations,Wataae-Devil Canyon Operation,Late Stage III ii I I I NUI:lber t. I 2. I 3. I 4. I 5. I 6. I 7. 8. I 9. I 10. I 11. I 12. I 13. I 14. I 15. I I I LIST or EXHIBIts Title Strea.Caging Stations Susiena River ~t Gold Creek,Water Discharge Va.Suspended Sedi.ent Concentration Susitn.River at Sunshine,Water Discharge Va.Suspended Sedi.ent Concentration Suspended Sediment Size Distribution,Susitn.River nr. Denali Suspended Sediment Size Distribution,Susitn.River nr. Cantwell Suspended Sediment Size Distribution.Susien.River at Gold Creek Suspended Sediment Size Distribution,Susien.River nr. Talkeetna Suspended Sediment Size Distribution,Chulitna River nr. Talkeetna Suspended Sediment size Distribution,Talkeetna River nr. Talkeetna Suspended Sediment Size Distribution,SusieD.River at Sunshine Suspended Sediment Size Distribution,Susitna River at Susitna Station Susitn.River at Gold Creek.Monthly Suspended Sediment Concentrations Susitn.River at SunShine,"ont~ly Suspended Sediment Concentrations Watana Reservoir Outflow,Suspended Solids (Stage I),Low Inflow Year Wat.na Reservoir Outflow Suspended Solids (Stage I),High Inflow Year iii I I I Nu.ber 16. I 17. I 18, I 19. I 20. I 21. I 22. I 23. 24. I 2~. I I I I I I I I • LIST or EXHIBITS (coatiaued) Title Watana Reservoir Outflow Suspended Solids (Stage I),Average Inflow Year Watana Reservoir Outflow Suspended Solids,Stage II,Average Year Devil Canyon Outflow Suspended Solids,Stage II,Average Year Watana Reservoir Outflow Suspended SoLids,Late Stage III. Average Year 1982 Devil Canyon Reservoir Outflow Suspended Solids,LAte Stale III,Average Year 1982 Watana Reservoir Outflow Suspended Solids,Late Stage Ill, Average Year 1983 Devil Canyon Res~ryoir Outflow Suspended Solids,Late Stage Ill,Average Year 1983 Susitn.River Progression of Ice Front.Stale I Susien.River Prosression of Ice Front,Stage II Susitn.River Progression of Ice Front,St_ge III iv • I I I I I I I I I I I I I I I I I I I 1.0 SUMKARY The concentracions and particle size distributions of suspended sediment were determined for natural and with-project con~itions on the Susitna River at Gold Creek and Sunshine stations.The estimates for the natural condi- tions were based on data collected by the United States Geological SUI .~y. Under with-project conditions,the concentrations were estimated using the concentrations 1n the Wacana Reservoir releases and those frOlll the area intervening between Wacana and Gold Creek,and between Wacana and Sunshine. The concentrations in the Wacana Reservoir releases were determined using dynamic reservoir simulation model (DYRESH). It is estimated that the average suspended sediment concentration of all flows entering Watana Reservoir will be about 830 milligrams per litre (mg/l).For Stage I,the summer suspende~sediment concentrations would decrease from about 60-3000 mg!l to about 60-150 mg/l and the winter concentrations would increase from about 1-80 mgll to about 20 -100 mg/l. For Stage II operation,these concentrations will be about 10-20 percent smaller than those for Stage I operation. The larger and deeper Stage III reservoir at Watana would further reduce the suspended sediment concentrations at Devil Canyon.The estimated concen- trations in the releases frOCll the Devil Canyon Reservoir would reach their lowest values of about 15 to 20 mg/l in April or Hay and approach a maximum of about 90 to 100 mg/l in July or August. The estimated mean monthly suspended sediment concentrations at Cold Creek and Sunshine for Stage I ~nd late Stage lIt are shown on Exhibits 12 and 13. Project operation would increase the concentration during winter and decrease that during summer.At Cold Creek,November through March concen- trations approximately would incr@as@ from about 5 mgtl under natural condi- tion~to between 40 and lOO mgll for Stage I.The concentrations ,.,ould decrease back to between 25 and 75 mg/l for Stage III.The increase at 42189382 851217 I I Sunshine would be from about 5 mgll under the natural conditions to bet~een be nearly the same as under natural conditions while the October c:oncentra- redu~cd back to between 25 and 60 m&/l.The concentrations in the months of April and October at Gold Creek also will increase compared to those under 35 and 75 mgll for Stage l. I I natural conditions. For Stage [[I,the concentrations would ~e At Sunshine,the loo'ith-projec:t Hay concentration wuuld through September will decrease at both locations (Exhibits 12 and 13).I I I I I I I I I I I I I cions would be lower (Exhibits 12 and I]).The concentrations during May I I 42189382 851217 2 --------------~----~ I I I I I 2.0 B.A.C~.omeD The first draft of this report was issued in June 1984,and was reviewed bt various members of the Aquatic Study Team.Their comments were included in the second draft issued in November 1984.The analyses presented in those [1010 drafts were made for a two-dam,two-stage development.Also the with- project suspended sediment concentrations at Wat"n.were derived from a study made by Peratrovich,Nottingham and Drage,Inc.;(PHD,1982)1/. divided into early Stage tIl and late Stage III based on two energy demand scenarios. As of April 1985.a two-dUll,three-stage developaaent is be ins cons idered. Stage I would be a low Watan.(noraal pool elevation -2,000 fc)devdop- ment,Stage II would be a low Watan.-Devil Canyon (normal pooL ~levation • 1,45>ft)development and Stage III would be high Watana (normal pool I I I I elevation·2,185 ft)Devil Canyon development.Stage III is further I I I I I I I This report presents the analyses made for the two-dam three-stage project. The with-project suspended sediment concentration estimates also have been revised based on new analyses. I 1/Indicates reference at the end of text. I I 42189382 851217 3 I I I I I 1.0 SCOPE OF TR!STUDY The scope of this study includes the analysis of suspended sediment concen- trations under natural conditions aoJ changes in the estimated concentra- tions due to project operation.The 3nalysis is made for the Su~itna River at the Watana site,Gold Creek and Sunshine stream gaging stations (see Exhibit 1 for the locations).The major tasks are to: 2.define the characteristics of suspended sediment entering Watana Reservoir; I I I I I I I I I I I I I I 1. 3. 4. 5. 42189382 8;1217 define the characteristics of suspended sediment at selected loca- tiens upstream of the Sunshine stream gaging station (Sunshine gage); estimate probable suspended sediment concentrations of water released from the rese~voir; evaluate effects on suspended sediment concentrations in the main- s tem due to major tributaries entering the Sus itna River above Sunshine gage;and provide a comparison of monthly suspended sediment concentrations at Gold Creek stream gaging station (Gold Creek gage)and at the Sunshine gage for natural and with-project conditions. 4 I I I I I I I I I I I I I I I I I 4.0 S!TTIIIC The Susitna River drains an area of about 19,&00 square milf"s (mi 2 )in the south central region of Alaska.The major tributaries include the CtulieD., Talkeetna and Yentna rivers with drainage areas of a:"out 2,650;2,040 and 6,200 mi 2 respec!lvely. The Susitna Rive:-originates in the West Fork,Susitn.,East Fo:k and Maclaren glaciers of the Alaska Range (Exhibit 1)and travels a discance of about 320 miles to its aouth at the Cook Inlet.roe Chulitna River ~rili nate.in the glac.iers on the south slopes of Hount McKinley and j)ins tbe !iuaien.River from the west near Talkeetna at river /Dile (RM)93 (river miles referenced frOlll the Cook Inlet).The Talkeetna River originates in t he Tal keetna Mountains and jo ins the Sus i tna Ri \"er f rcxn the ~as t near ralkeetna at RM 97.The Yentna River originates in the Alaska t.:ange and enters the Susitna River from the west at ~~28. The Susitna Hydroelectric.Project ..,i11 include two dams,Watana lind Devil Canyon.located at RM 184 and 152,respectively.The drainage areL8 at the two sites are about 5,180 and 5,810 mi 2 ,res~~ctively"The p~oject will be developed in three stages. Susitna streamflov i.characterized by turbid high flows frOlD May through September and clear low flows from October through April.High spring and summer flows are caused by snowmelt,glacial melt and storm rainfall. I I 4Z18938Z 851217 s I I I I I I I I I I I I I I I I 5.0 SUSPENDED SEDIMENT 5.1 DATA SOURCES Suspended sediment samples have been collected at a number of stream gaging stations in the Susien.River basin by the United States Geological Survey (USGS)(USGS Water Resources Data)and R&H Consultants (R&H,1981).These ...ples have been analyzed for [otal suspended sediment concentration in .g/l.A number of a_pLes also have been analyzed for particle size dis- tribution.Exhibit 1 shovs the sampling stations for which the suspended sediment data are available.The numbers of samples collected at selected stations by the USGS during the period of record are given in Table 1.R&H Consultants also collected about 10 samples at Cantwell and 8 samples at Gold Creek stream gaging stations during 1980 and 1981. 5.2 CHARACTERISTICS OF SUSPENDED SEDIMENT Sediment is transported in suspension.as bed load rolling or sliding along the bed and interchangeably in suspension and as bed load.The nature of movement depends on the size,shape and specific gravity of the sediment particles and the associated flov velocity and turbulence.Under some conditions of high flov velocity and turbulenc~(such as those in steep- gradient oountain streams)cobbles (64 to 256 mm size)can be carried.inter- mittently in suspension.Conversely.silt size particles (.004 tu .062 mm) may mOve as bed load in lov-gradient.lov-velocity channels. 5.2.1 At Selected Locations Suspended sediment is the tediment that is transported outside of the bed layer in suspension by the turbulent components of the flow.In the Susitna River,fine material (silt and clay finer than 0.062 mm)and fine to medium sand particles (sizes between 0.062 mm and up to 1.00 tam)have commonly been observed in suspension. I I 42189382 8)1217 6 I I I I I I I I I I I I I I I I I The fiRe material,also known as wash load.is derived from sheet erosion, glacier melt and bank erosion.The qU4ntity of wash load being transported depends upon its availability because,for the observed range of flow,the Susitna River can transport lDuch larger quantities of wash load than has been measured.The coarse material (sand particles>moving in suspension is derived either from river bed erosion or from glacier melt and other erosion processes.The maximum quantity of bed material being transported in sus- pensior.depends upon the magnitude of flow. Suspended sediment samples at the USGS stream gaging stations generally have been collected during the months of Hay through October (Table 1).A few samples are available for some stations for the period from December through April but no sample has been collected in November at any station. Since the suspended sediment consists of wash load and sand particles,its concentration varies both with the availability of wash load and the capacity of flow to transport sand particles.Available data for Gold Creek and Sunshine gages are plotted on Exhibits 2 and 3,respectively,to show the variation of sediment concentration with water discharge.The maximum, minimum aud median concentrations measured at various stream gaging stations are listed in Table 2.The maximum and minimum concen:rations are not pro- vided for the months for which only one or two samples are avai lable.The median values in such cases are also not given. Knott and Lipscomb (1983,1985)analyzed the periodically observed sediment concentrations and corresponding water discharges and estimated monthly suspended sediment transport rates for the Susitna,Chulitna and Talkeetna rivers (Table 3).Based on the few months of concurrent data,the suspended sediment transport rates in the Chulitna River are significantly higher than those in the Susitna River above its confluence \lith the Chulitna River. Therefore,the suspended sediment concentrations in the Susilna River below the confluence are controlled by the Chulitna River.The size distributions of suspended sediment at various stations are given in Table 4.The size I I 42189382 851217 7 distributions are avaitable for the .amples collected during the months of May through October.A few samples collected during the other months were not analysed by the USGS for size distribution probably because of insuffi- I I I cient sediment quantity.The smoothed siz:e distribution curves based on I I I I I I I I I I I I I I I I Table 4 are shown on Exhibits 4 through 11.The percentages of fine mate- rial and sane!particles at various locations taken from these exhibir.s are given below. PERCENTAGES OF FINE MATERIAL AND SAND IN SUSPENDE~SEDIMENT Median Station Fine Materi.l Sand oi•. (<.062 _)(>.062 ...)(om) Susitn.R.nr.Denali 52 46 .056 Susitn.R.nr.Cantwell 54 46 .049 Susitna R.at Gold Creek 61 39 .038 Susitna R.nr.Talkeetna 70 30 .015 (above confluence) Chulitna R.nr.Talkeetna 62 38 .024 Talkeetna R.nr.Talkeet!la 51 49 .060 Staitna R.at Sunshine 69 31 .014 Susitna R.at Susitna Station 61 39 .030 The above table indicates an increase in the percentages of fine material frOlll Denali to above the confluence of the Susitna and Chulitna rivers. Dovnstrea~frOlll the confluence,the trend is not clear primarily because of sedilllent contributions frOlll the I114jor tributaries and partly because of lilllited nUlllber of samples available for the Susitna River at Susitna sta- tion. An insufficient number of samples are available at Sunshine and Gold Creek to precisely define the concentration for each month.Hovever,by referring to data for various stations,some indicative values of monthly concentra- tions for the Susitna River at the tvo stations were estimated as shown on Exhibits 12 and 13,respectively.The values indicated on the exhibits are not related to specific discharges and approximately represent the median values from the range of observed concentrations under natural flow condi- tions. 42189382 8 851217 I I I I I I I I I I 5.2.2 Suspeaded Sediment Entering Wacsa.Reservoir The characteristics of the su~pended sediment entering Wacana Reservoir are best re?resented by thQse measured at the Cantwell station.This indicates that,on the average,the suspended sediment concentrations may vary approx- i.~[ely between 0 to 10 mg/l from November through April and between 80 to 2,000 mg/l from May through October.The average size distribution based on the samples collected from Hay through October is shown on Exhibit 5.This indicates that about 18 percent of the suspended ,edi.ent is Less than .004 am (clay sizes),about 36 percent is between .004 and .062 (silt sizes)and about 46 percent is larger than .062 ....(sand sizes).About 97 percent of the suspended sediment is finer than .500 ma.The average annual streamflow at Watans is about 8,000 cubic feet per second (cfs)(H-F:,February 1985). The suspended sediment inflow is estimated to be about 6,530,000 tons per year (ton/yr)(H-E,April 1984).This gives an average concentration of about 8)0 mgll for the flow entering the reserV01r. 5.3 EFfECTS OF ICE COVER ON SEDiMENT TRANSPORT I A study made by w.w. effects of ice-cover Sayre and G.B.Song (Sayre,1979)to evaluate the on alluvial channel flow and sediment transport I I I I I I processes indicate~that ice causes a number of changes in alluvial channel flows by appr~ximately doubling the wetted perimeter and thereby producing a redistributio~of the boundary and internal shear stresses.The total depth of flow in the channel with a given unit discharge and slope is significant- ly increased (about 20 to 30 percent for a smooth cover and from 30 to 80 percent for rough cover,relative to the depth for a free surface condi- tion).Due ma:'nly to the lower 'Ielocitiea.sediment discharge is signifi- cantly reduced. The above conclusions are applicable to the Susitua River for the period between early November and mid-Hay when an ice cover is generally present. I I 42189382 851217 9 1 1 1 1 1 1 1 1 1 1 1 -I 1 1 I I 1 5.4 SEDIMENT TRANSPORT DURI~C FREEZE-UP Field observations on the Susitn.River show that freeze-up generally begins in October and generally continues until break-up in earLy to mid-Hay.The beginning of frazil ice (a spongy or slushy accumulation of ice crystals which form in supercooled vater that is too turbulent to permit coagulation of the crystals into sheet ice)is marked by a rapid reduction in suspended sediment concentration.As the process continu~s.the river becomes clear vithin a day or tvo.The contributions of fine sedilllent from the erosion proce••and fra.alacial flour are stopped due to frozen around and the eli.in.tion of glacier melt.The river real.ina practically clear until breakup. The frazil crystals often flocculate into larger clusters.Since water can permeate through these clusters,they filter out sediment particles which remain entrapped 10 the ice.During breakup,a significant quantity of lediunt,mOltly silt and clay,is observed to be mixed with ice.The sedi.ent is concentrated at places rather than distributed over the whole Anchor ice,similar to slush ice but adhering temporarily to the river bot- tom,also has been observed to be mixed with sediment.The anchor ice prob- ably catches sediment moving as bed load as veIL as suspended load.The anchor ice is generally formed at night and released during the day and then drifts downstream. 5.5 PROJECT EFFECT 5.5.1 Suspended Sediments Concentrations at Watana leservoir Outlet Peratrovich,Nottingham and Drage,Inc.;(PHD)made an analysis of turbidity levels in the Watana Reservoir using a computer model D~POSITS (PHD,1982). The major conclusions made by PHD that are pertinent to this study are given below. I I 42189382 851217 10 2.Maximum sediment concentrations in the Wacana releases would be I I I I I 1. 3. Sedilaent particles of about .004 ..and less will remain in sus- pens ion; between 200 and 400 mall;and Miniilulll sedi.ent concentrations in the WaC_D.releases wouLd be between 30 and 70 -all. I I I I I I I I I I I I Harza-Eb.,co studied the suspended sedi.ent characteristic.10 the Wacan. Reservoir and in the outflow from the re.ervoir for the tvo-dam,three-stage project.The purpose of the study va.to refine the analysis made by PND. The DYKESM .-odel (Iaberler and Patterson,198U.used for the reservoir teaperature and ice study,vas enhanced to incLude ..sub-routine to simu- late,on ..daily basis,the vertical distribution of suspended sedimenc~in the reservoir and the suspendp.d sediment concentration in the outflow.The .odel considers the sediment .ixiDg due to meteorological forcing.turbu- lence,density currents and externaLLy specified vertical settling velo- cities.The effect of the ice cover on the suspended sedi~ent concent~ation also is considered.Compared to DYRESM.the DEPOSITS f.ilodel used monthly inflow data and thus,was Dot reaponaive to rapidly changing sediment in- flows during floods.The efiects of stratification,density currents and ice cover also were Dot considered. For the Stage 1 operation (Watana only.normal pool elevation -2,000 ft). the suspended sediment concentrations in the reservuir and the outflow were s i.u!ated us ing the enhanced version of DYRESM model;1970,1981 and 1982 flow conditiona with Case [-VI downstream flov requirements (H-E,November 1984)and daily suspended sediment inflow rate..The water years 1970,1981 and 1982 were judged to represent near minimum,maximum and average suspend- ed sedi.aent inflow conditions,respectively.Daily aediment infLov rates vere estimated for these years by transposing the corresponding data at Gold Creek.The transposition vas made using the procedures discussed in a I I 421~9382 851217 11 I I I previous report (H-E,April 1984).The amount of suspended sediment cor- responding to a given ranal!of sediment particle sizes was estimated using the particle size distribution curve shown on Exhibit 5. Results of the simulation indicated that all sizes above 10 microns would settle out in the reservoir.A large portion of particles wit\1 sizes between 3 and 10 microns also vo~ld settle out.The particle sizes up LO 3 .ierons would rea.in in suspension for a 100&period due to low settling velocities and thus would constitute the ...jor part of suspended sediment concentration during winter .oaths.Exhibits 14,15 and 16 show sediment concentrations in the outflows from the Wateae Reservoir.The concentration I I I I I 18 nearly constant from July Deceaber through early l1ay when the average and range of monthly through November and then decreases from it reaches a minimum value.Table 5 gives concentrationG under Stage I conditions. I I I I I I I I I therefore,the downstream suspended sediment concentrations near the project site will be affected by the operation of the Wataaa Stage 1 Reservoir.The sumaer suspended .ediaeat level would be decreased fra.about 60-3,000 mgll to about 60-150 ..11 and in the winter,the level would be increased from about 1-80 mall to about 20 to 100 mg/l. The enhanced DYRES~-odel wa.also applied to simulate the suspended sediment concentrations in the Watana and Devil Canyon reservoirs using Case E-VI downstream flow requirements,Stage 11 energy demand level and 1982 sediment inflow conditions (average year).The sediment inflows for maximum and minimum sediment conditions were not simulated ~ecause the analyses made for three scenarios for Stage 1 can be used to provide!an indication of relative changes for minimum or maximum sediment inflows under Stage 11. Table 6 suaatrizes the results of the analysis.Exhibits 17 and 18 show the esti..ted suspended sediment concentrations from the Watana and Devil Canyon reservoirs,respectively.These exhibits indicate that a s.all quantity of particles sizes below 10 .icron.also would settle out in the Devil Canyon Reservoir.The suspended sediment concentration in the Devil Canyon I I 42189382 851217 12 1 1 1 -I 1 I 1 1 1 1 Reservoir releases wouLd be about 10-20 percent less than that frOID the WaCan.Reservoir under Stage I. The enhanced DYRE~M model also vas appLied to simuLate the suspended sedi- ment concentrations in the Watana and Devil Canyon reservoirs using Late Stage III energy demand level,Case E-VI dovnstream flow requirements,and 1982 (average year)sediment inflow conditions.The results of this ana1y- .is are given in Table 7 and also shown on Exhibits 19 through 22.As under Stale It conditions.a a••ll quantity of particles with sizes below 10 .ierona wouLd settLe out in the Devil Canyon Reservoir.The suspended sedi- ment concentrations in fhe releases from the Devil Canyon R~servoir would be more unifo~during su_e:r cOfDpared to those under natural condit ions. Under late Stage III conditions,the suspended sediment concentration in the Watana releases would be less than that under Stages I and II.During the months 01 July and August this reduction would be about 50 mgll.This i. due to the larger and deeper Watana Reservoir in Stage III.Correspond- ingly,the suspended sediment concentration in the releases from the Devil Canyon Reservoir would be less under Stage III than under Stages 1 and II. 5.5.2 River Water Temperatures The extent of formation of ice cover on the Susitna River downstream from the reservoirs will depend upon the reservoir outflow temperatures and their For late Stage Ill,the suspended sediment concentration in the releases from the Devil Canyon Reservoir,would reach its lowest level of about 15 to 20 mgil in April or May and approach a maximum of about 90 to 100 mgll in July or AugUSt.These results are based o~the simulation of average flow conditions during 1982.The ~orresponding values for a low or high sediment inflow year can be estimated by the relative decrease or increase for these years for the Stage I simulation. 1 1 1 1 I I effect on river water tetllp~ratures.5t:-cause the formation of ice cover 1 affects the sediment transport .s discussed under sub-sectiQn 5~3.an evalu- ation of with-project river water temperatures was made. I I 42189382 851217 13 I I I I I I I I I I I I I I I I Harza-Ebasco has conducted a water temperature and ice study for the Watsna and Devil Canyon reservoirs and a river ice study for the reach between the Devil Canyon Reservoir and the confluence with the Chulitna River.The study results are presented in the draft License Application Amendlllent ~~hibit E,Chapter 2,Water Use and Quality (APA 1985),and in a report on ice simulations (HE November 1985)for the three-stage project.The study indicates that the outflow temperacures at Wacan.under Stage t can be controlled to approximate the natural instrea&temperatures using multi-level intakes.The outflow te-peracures under Stage 1,would range between S·C and 12·C in the suamer and between a.s·c and J·C in the winter depending upon the meteorological cor.aittons.Under Stages II and Ill,the outflow temperatures from the Devil Canyon Rese~voir would be between 1.S·C and J·C in the win'er and between 4·C and lO·C in the summer. The Arctic Environmental Information and Data Center (AEIDC)has conducted river temperature studies (Exhibit E,Chapter 2.APA 1985)to investigate project effects on the river reach downstream from the dames)to Sunshine. For all three stages of the project,the river temperatures between the dames)and the end of the ice cover,were predicted to be between O·C and 2° to J·C in comparison to aoc temperature in the same reach under natural conditions.Exhibits 23 to 15 show the positions of ice fronts for the three stages.Since the river temperatures during winter would be higher thau those under natural conditions,frazil and anchor ice formation activi- ties would be reduced.This would result in a decreased entrapment of suspended sediments by frazils. 5.5.3 Suspended Sediment Concentration between Watana and the Chulitna Confluence The suspended sediment concentration in this reach will be controlled by the concentration in the reservoir releases (sub-section 5.5.1)and any sediment contribution from the reach. The suspended sediment concentration in the reach above the ice front will be nearly the same as in the releases.Any reduction caused by frazil and anchor ice will be compensated by sand particles pici<.ed up from the river I I I 42189382 851217 14 I I I I 1 1 •••• •• ·1 • I I I I bed because of higher willter flow.The formation of ice in the reach between the ice front and the confluence will reduce the sediment tran'Fort capacity of the river and some sediment could be trapped by ice.However, the reduction in the concentration will be relatively small.Therefore,the with-project winter suspended sediment concentrations would be about the same as in the outflows from the Watan.Reservoir under Stage I and from the Devil Canyon Reservoir under Stages II and III.Durio.SUaDer flood periods,the contribution frOlI the iatervening areas uy increase concen- tration.in the ..in.tre••but the concentration vould be significantly les. tban tho.e under natural condition••Exhibit 12 show.approximate suspended sediment concentrations during various months at Gold Creek for an average flow year. 5.5.4 Suspended Sediment Concentration between the Chulitn6 Confluence and Sunshine In this reach two major tributaries,the Chulitna and Talkeetna Rivers,join the Susitna River.These rivers carry little sediment during winter (Table 2)~Under with-project conditions.the increased vinter flow vill pick up sand particles from the main channel of the Susitna River.However,some of the sediment will be trapped by ice,and the net increase in sediment con- centrations will be insignificant.The concentration during vinter will, therefore.be controlled by the concentration in the Susitna River above the confluence.Durinu suaur months,loy concentrations in the Susitna River above the confluence will reduce the concentration at Sunshine compared to that under natural conditions.The monthly concentrations at Sunshine gage vere estilUted based on monthly suspended sediment concentruions and dis- charges observed in the Chulitna and Talkeetna rivers,vith-project monthly discnarges and concentrations in the Susitna River above the confluence and flow contributions frOl'l the intervening area.The with-project monthly discharges vere those computed for various stages based on Case E-VI down- stream requirements.Exhibit 13 shows approximate suspended sediment con- centrations during various months at Sunshine for an average flow year.The minimum concentration is about 25 mgll in March,with the maximum concentra- tion of about 675 mgll in August. I I 42189382 8Sl217 1; I • • • • • • •'. • I I I I I I I I I REFERENCES I I I I I I aF!UIfC!S Acres A:Derican Incorporated,1982:Feasibility Report,volume 4,A?peciix A.Hydrologic Studies,Final Draft,Susiena Hydroelectric Proj~ct. prepared for the Alaska Power Authority,also subsequent update5. Alaska Power Authority,1985:Before the Federal Energy Regulatory COfllI!iS- sian,Project No.7111.,Amendment to the Application for License for Major Project (Draft).Susitna Hydroelectric Project,prepu~d by Harza-Eb.sco Susitna Joint Venture. Harza-Eb••cQ Susitna Joint Venture,Su,itna Hydroelectric Project.A,>ril 1984:Reservoir and River Sedimentation.Final Report.prepared for the AI.ska Power Authority. Harza-Eb.scQ Susitna Joint Venture,Susitna Hydroelectric Project,Nov,~ber 1984:Evaluation of Alternative Flow Requirements,Final Report,pre- pared for the Alaska Power Authority. I I I Harza-Ebasco Susitna Joint Venture,Susitna Hydroelectric 1985:Case E-VI Alternative Flow Regime,Appendix D, Watana and Devil Canyon,Steeamflow time Series, Alaska Power Authority. Pro:ect, Susitna prepared February Riv ~r at fOl'the I Harza-Ebasco Susitna Joint Venture,November 1985,Instream Ice Simulations, Supplementary Studies for the Middle Susitna River,prepared for t~e Alaska Power Authority. Knott,J.H.,and ~.w.Lipsco-b,1983:Sediment Discharge Data fo~Sele:tetl Sites in the Susiena !liver Basin,Alask..,1981-82,U.S.Ge"log',cal Survey,Open File Report 83-870,prepar i in Cooperation with the Alaska Power Authority. I I I Imberger,J.,and J.C. Hodel,DYRESM:5, Chapter 9,Academic Patterson, Transport Press. 1981, Models A Dynamic Reservoir Simuktion for Inland and Coastal Waters, R&H Consultauts,Susitna Hydroelectric Project,1981:Water Quality AnnuJ.1 Report,prepared for Acres American Incorporated,for the Alaska Pov!r ~uthority. Susitna Reservrir for Acres Arterie an I I I I Knott,J.K.,and S.l.'.LipscOlllb,1985:Sediment Discharge Data Sites in the Susitna River Basin,Alaska,OCtober 1982 1984,u.s.Geological Survey,Open File Report 85-157, cooperation vith the Alaska Power Authority. Peratrovich,Nottingham and Drage,Inc.;November 1982: Sedimentation and W~ter Clarity Study,prepared Inc.,for the Alaska Power Autbority. for Selected to Februuy prepared in I I 42189382 851217 16 U.S.Geological Survey:Water Resources Oata for Alaska,Water Resources Division,Anchorage,Alaska,published 4nnually by w.t~r year. Sayre,W.W;and G.B.Sana.February 1979:Effects of Ice Covers on Alluvial Ch3nnel Flow and Sedi.ent Transport Processes.prepared for u.s.Geo- lOlie.l Survey.lIKe.Report No.218,low&:nstitute of Hydraulic Research,The University of Iova,Iowa City,[ova, I I I I I I I I I I I I I I I I I I I 42181382 851217 17 I I I I I I I I I I I I I I I I I I I TABLES I I I I I I I I I I I I I I I I I I I Table 1 SUSPENDED SEDIHENT SAMPLES COLLECTED AT USGS STREAM CACING STATIONS Months J F M •M J J •S 0 N 0 Stn••Gaging Stations Period No.of Samples SusHn.River nr.Denali 1961-62;964-66 1968;t974-75j 1977 ;1979-82 7 8 12 9 8 3 - Susitna River Dr.Cantwell 1962-72, 1980-82 3 11 .4 9 12 3 Susitn.River at Gold Creek 1962;1974-82 3 4 9 7 9 9 8 5 Susitn.River nr.Talkeetna 1982 ---5 4 5 I -- Chulitna River Dr.Talkeetna 1967-72, 1980-82 4 2 4 10 10 8 ~2 - Talkeetna River nr.Talkeetna 1966-82 8 7 7 12 13 16 23 12 1 SusitDa River at Sunshine 1971 ;1977; 1981-82 2 I 7 8 3 Susitn.River at SusitD.1975-81 2 3 2 3 4 6 4 2 2 Station -- -- --- -----0---- ---Table 2 SUSPENDED SEDIMENT CONCENTRATIONS,HclL (Perlod 1962 to 1982) Hontha Station Jan 'eb Har Apr Hay Jun Jul Aug !!.P-O.t Hoy ... Sualto.R.or.Denali Hax.- ---1190 1600 2770 5690 3600 1400 Htn.--- - 102 302 886 350 124 85 Median - - --570 840 1350 890 293 104 Sualtna R.or.Cantwell Hax.----726 1860 2790 1040 170 140 Hln.-- - -132 172 632 380 34 6 Medtan - - - -661 417 1090 755 138 84 Susltna R.at Gold CreekJi Hax.8 -3 -11,0 1400 130 938 812 22 Hln.0 -I -65 151 '00 158 23 7 Median 2 -2 -498 574 394 420 68 10 Suattna R.or.Talkeetna Hax.- - - --769 768 341 HI n.- ----181 145 219 ~Iedi.n --- --438 422 285 Chulitna R.nr.Talkeetna Hax.--21 -1040 1600 2200 1260 1680 Htn.- - 4 -500 90 717 694 129 Median - -12 -675 820 1165 817 396 Talkeetna R.nr.Talkeetna Hax.15 -11 48 503 1J40 1160 3530 3'0 19 Hln.2 -I 2 21 111 90 38 13 8 Hedlan 8 -3 8 123 309 359 466 80 16 Bualtns R.at Sun.hine Hax.- - ---16)0 1430 3510 Hln.---- -360 503 424 Ked tan - - - --102 713 115 Su.ltna R.at Sualtna Station Hax.--5 -572 918 1490 1490 Hln.- -3 -378 326 561 483 Median - - 3 -411 503 852 943 11 U.S.Ceologlcal Survey.Water Supply Paper NO.1500 gtves 88[t.ated .eao dally concefltutton of 2.730 on July 16.1951.. ------------------- Table 3 ESTIMATED MONTHLY SUSPENDED SEDIMENT TRANSPORT AT 1'HI::SELECTED SITES ON THE SUSITNA RIVt!R Suspended Sediment Load (10 3 tons) Stream Caging Station Year Jan.F~b.Mar.~~Jun.Jul.~~Oct.Nov.Dec. Susiena R.nr.Talkeetna 1982 300 800 880 359 470 9.3 .78 .72 (above confluence)1983 .79 .62 .34 .50 350 920 1080 980 121 Chulltna R.or.Talkeetna 1982 130 1280 2650 1400 1690 (above confluence) Chlllinta R.below Canyon 1982 37 5.i 2 .• or.Talkeetna 1983 1.9 .63 .72 1.1 250 1660 2760 3200 630 (below confluence) Talkeetna R.or.Talkeetna 1982 ~O 400 510 138 242 10 .85 .63 (abave conf Lucoce)191:13 3.8 .14 .15 .23 46 220 430 350 23.8 Susitna It.at Suntlhlne 1982 600 2700 4200 2400 2270 110 4.5 3.2 1983 2.7 1.7 .78 1.7 930 )400 3900 4700 690 -- ------- - --------- Table 4 PARTICLE SIZE OISTRIBUTION 010'SUSPENDED SEDIMENT No.Particle Size (mm) Stro:am Gaging "If lJ .002 .004 --.008 .016 .031 .062 .125 .250 .~OO 1.000 ::)tatLon ~8mple -PCrcen'tFtner ThanV-------- SusLlns River 34 12 16 23 11 41 53 64 81 96 100 nr.Dcnall Sustens Itty!;!r 27 12 18 25 33 43 54 67 86 97 'uu oc.Cantwell SUClltna River 24 15 19 27 35 47 61 75 86 98 100 at Cold Creek SusLtna f{lvtlr 13 29 35 53 72 79 90 100 nr.T8lkt~etna Chulltll;'ll{lyer 36 21 31 37 46 55 62 72 85 99 100 nl'".Talkeetna Talkcelllil Rlv!;!r 16 9 16 22 31 41 53 65 85 9.100 Ilr.Talkeetna Susllna Rivt:r 11 22 33 43 53 62 67 7'90 100 fit Sunshl nc SUf>llna River 9 16 23 33 43 5'60 82 94 IOU at Sus1tna Station 1./Sllillpies foC'w/!tYch full range of size distributions wert!analyzed. !ot The PI:!rcen [8 teli gl veil a re the mcd tan va luel>f rom a range of oberved percentages for va r LQUS S I ZCII. ------------------- Table 5 SUSPENDED SEDIMENT CONCENTRATIONS (HG/L) WATANA OPERATION.STAGE I Average ConcentratIon Range of Concentration In Reservoir ReleasesJJ in Reservoir Rele.Beall Range of ObserlJd Range of EstlMai'd 1970 1982 1981 1970 1982 1981 Honth Concentration Concentration (Kinl'l1tlJlll)(Average)(Hn:1...IIl)(IUnluulll)(Avera.&!l.(Halli ....et Jan 1-8 2-55 65 65 85 40-90 45-85 SO-120 'a6 NiA'll 2-93 40 55 65 20-70 JS-7U 30-95 Har 1-6 2-23 30 40 45 10-SO 20-60 20-75 Apr NiA 2-183 25 30 50 1O~40 10-50 20-75 Hay 65-1,110 5-1,480 20 35 45 5-SO 10-65 10-70 Jun 151-1,860 620-1,705 75 85 90 35-90 45-145 70-95 Jul 100-2,790 506-2,062 105 130 110 85-115 120-145 70-190 Aug 158-1,040 198-2,150 105 110 165 90-115 85-125 130-200 Sap 23-812 5-1,511 95 90 130 85-105 85-100 100-'70 Oct 7-140 2-144 85 100 125 80-100 90-110 100-140 Nov NiA 2-71 90 95 115 75-100 85-110 90-130 Oac NiA 3-47 80 85 95 60-90 70-95 70-110 1/From Table 2 using data from the Susitn.River near Cantwell (period 1962-72,1980-82)and at Gold Creek -(period 1962,1974-82). 2/E~tLmated from daily sediment transport In tons per day and corresponding mean daily discharge in cta at Watana,1970.81 and 82 flow conditions. II Based on OYRESH simulation results. ~I N/A·not available. Table 6 N/A •not available. Rased on DYRESH simulation for 1982,releases from Devil Canyon Reservoir. From Table 2,using data for the SUs1eRs River near Cantwell (period 1962-72, 1980-82)and at Gold Creek (period 1974-82). 50-75 30-60 30-50 25-35 10-35 20-100 70-140 80-130 70-130 7>..85 75-80 60-80 Range of Concent rat.ionlJ (Averge Year) 60 45 40 30 30 55 1I0 1I0 90 80 80 75 Average ConcentrBt lonll (Average Year) 1-20 1-30 1-20 30-170 130-1,270 930-1.470 600-1.600 200-1.070 200-1 .530 I-JO 1-30 1-30 Rallge If ConcentrationlJ SUSPENDED SEDIMENT CONCENTRATIONS (MC/t) WATANA -DEVIL CANYON OPERATION,STAC~II 1-8 NI..';J 1-6 NIA 65-1,110 151-1.860 100-2.790 158-1,040 23-182 7-140 Nil. NIA Range of Observed Concentratlonl! Estimated from daily sediment transport In tons per day and corresponding mean daily discharge In cfs at Watana,1982 flow conditions (average year). Jan Feb Har Apr Hay Jun Jul Aug Sep Oct Nov Qec II ~I Mont.h 1.1 '!.I I I I I I I I I I I a I I I I I I I I Average Range of Range of Observed Range of Concentration1l ConceRt rat lon1J Month ~ncentratlon1l ConceDtr.tiaRY (Average Year)(Averge Year) Jan 1-8 1-20 55 40-70 Fob N/iM 1-30 50 30-65 Har 1-6 1-20 25 14-40 Apr N/A 30-170 25 15-40 Hay 65-1,110 130-1,270 20 10-30 Jun 151-1,860 930-1,470 35 15-60 Jul 100-2,790 600-1,600 75 60-100 Aug 158-1,040 200-1,070 75 55-100 Sop 23-182 200-1,530 55 40-70 Oct 7-140 1-30 50 40-65 Nov NIA 1-30 70 65-70 o.c N/A 1-30 65 55-70 I I I I I I I I I 1"/ 111 1 1/ '!/ I I I I I I I Table 7 SUSPENDED SEDIMENT CONCENTRATIONS (HelL) WATANA -DEY rL CANYON OPERATION.LATE STAGE [l I Pro.Table 2.using data for the SusitD.River near Cantwell (period 1962-72. 1980-82)and at Gold Creek (period 1974-82). [.t1.aced fro.daily sediment transport in tons per day and corresponding mean daily discharge in cia at Watana,1982 flow conditions (average year). Based on DYRESH simulation for 1982.releases from Devil Canyon Reservoir. N/A •not available. ~ I I I I I I I I I I I I I I I I I I EXHIBITS " ., ",CL"'''I,l; ILAClr" EXHIBIT 1 .. / SUSITNA HYDROELECTRIC PROJECT STREAM GAGING STATIONS J "o'.'~-~.0<18'. ~ DCVll CANYON O'UII'U:OOLD t::IlCU / . ALASKA :-'"RANGE ~4rI'...<. "'(li'l" _GLACIER ~RIYEA ..STRE"'"GAGING AND SEDIMENT SAMPLING STATION •CITY OR TOWN 0""SITE ...__c'i.I__-'·i.·__-'·i...__.......:...._---'..IlILI. HA"ZA ..EB"'SCO IUSITN"JOINT VENTUftl I I I I I I I I I I I I I I I I I I I I i !I l _j ,,-, ,, I -i .. EXHIBIT 2 , I -.- '~. , l ' ..I klrrci:ro'E"'CCCTRrc-PROJECt t I ·U.aLUtA..,R.UlER-AT GOLD CREEK , ' Ol.I I.ISCHAR,GLlis........SUSPENDED SE.OIME.N.:· .~CON'cEN'[FiATlON (MG/L)I-,--;-rn "':1'-."L WATER DISCHARGE,eFS HARZA-EBASCO SUSITNA JOINT VENTURE ...,.---- --.--'O~..... .' ., (1..-.:;. i~'. '!' i" I I I I I I I I I I I I I I ,, I I I ', I I t :J , '.1. EXHIBIT 3 -c- --1-- " .' WATER DISCHARGE,CFS ,..--,., - ----j ..-........- -r-' ...... ,., 10"-..~.""~~.- I • I •••i• I •••I; _.IOZ •r f-'--;'"=j~",,-=---=?=t='~~'~:;~DRJElE I.,-'., :It';=1~~~~!!!II~I~:::=E:'1 SiT i .'i "-cIRi~-PAO~ECT'T...l....L.!.-'!'•§i:~_.sri.N-A RIVER AI'GOLD CREEK..._~C+-H f 9:~"8 G E:•V.n -SUS eEN0 ED....S ED.1"'i'''!J'Ft-l~ONCe.~~OId"G/i.},I. I I I I HARZA-EBASCO SUSITNA JOINT VENTURE --'-+--.. 1--'\.l ~1r'+--\-T-0'< ,"tl •..i •t::••,--.';.+- ---t l-.,--< I--"<>-c;"w""""" "",-co ..........."N "<t-N' ------""<3ZIS Q3.1VOIONI NYH.l t:I3NI~.lN30t:i3d ,"'I, j - " " .-.:. :..~- !", ,- , --...-.-1 - .; ---r': EXHIBIT .. , ':-:::i~-:-::"I -.t::' .-. ., '- I W lD-r-;--- o cr-:;;-+--+-,.-."'", I-<_-J,-__~_••-I- 1-__CL~~ L-+-+-++~~-:"0 ---' ~_'___+.-_---~'~_~_~~a:o.,z w "'~w!-iP- "'~00<w-Z ••, •• ••, •• , • ,••, •, ,••, • I I I I I I N I~ ~• I I I Ii, >, I ••:: o'O' I "0,·. "'>" I "<'.-i:-1= I ""'•X I I I I w, --<- Hi '"<I"', j ... °--"z-...3 -----, o i !, o EXHIBIT 5 <0-...w ZO", Z""'W'""..--Jf-----<",,,,, "'" c-. o N -_.f-- \ j \ 1\ UL.".,!!!wl_-I-__~TL-='=i' 0:,..~; ----+--~-+_D..'"1--~---___1Z 0°< o:wu,..~ 0"'0: W,..Z -'z.. W "'-w"'>OJ!:>w,,,- ~.-·-.·'\.--- --··. 3ZlS C3.lVOIC.N1 NYH.L ij3NI~.LN3::J1:t3d ~.. o 0--0 a -0 0 0 .;"=---''''--~''~.--''''--~''''--_.'''--~'''''-- -.,, ~ !i·,··· ""i , i I ., I '",,,, i i-.'-'-'-~I f---I +, ·- -----~-!! i ,i , 0 I ~O -L -------y-o I I I, i ,, ••, •,I .1- ~, 0r- , ••, • • ,••, •• ,••, •, I I I I I I I I I I I I I o EXHIBIT 6 ":::~-+--..--'-+-:..:...--.:.. ~,------ o ~--o " "'CD 0'" ",'"teL'"o "'W....N 0" ! ,. - -;--- ., , -~---,- !"'-, I Ir--- !, r--. ••, •, • ••, • , ,••, •• I I I I I I I I >.. o... "'-< 0-W + 1\ 1'\ I ~- -I-. -.. ••, •, , .I~ :i: I I 3ZlS D3.lV~IDNI NVH.l t:l3NI:f .lN3:J1:t3d o 0 0 0 d 0 CI 0___m__CD__~,,-_~CD__"'__•__"'- I I I +- +-- f--. i --f ..+- o N o I o ;;; .< W,-, --,." N -"'-~I .~ t -~ >..-'0 - ___<II( Z-.. 0 ~. --<:.., <- HIa:.. ~I N + --'-o.. _0:.. <:".. o EXHIBIT 7 it oo ii---- -, ,,I I--\- c--!~-\ I \ -,'I I -.--.-----., ·-·- ,I ,-~-0 CD C-Z I-"'l<z :>~-'=..w .. f-_a:.,..~-.,w..0 "z "'w ..0 I ,<:0--,.a:N ...I ..w.., ·-0 a:'"w ..z .. z a:'"_W W-o ,,.•.~-2:-et 0 a:Ie> W --"'~"z<:O-~__r .,,,------,W .,a:,-L-f.,.0 :>..,-·-.-~1 --,, '\.'I i l~Z '"...,,.I W ....:>·\-, j OJ --.:>, '" -,--I 321S 03.LVOIONI N't'Hi ~3NL:t ..1.N30tt3d d 0 0-0 -0-0 0 0 0 f------,._'"--"'--.."'--"'--~~~'--"'--" I •••• . --, •,, -- -.- --••••I -- ~I ••, •, ,••••• ,••, •, I I I I I I I I I I I I -------------------K It':S["'·'OG."""··"C'C"C'U~IIlp,y,t'QNt 466212.C:dU"U ••.~s.~~o ••.••• ~.........- ........O'...... .. ..~......_4.._.... 10 1-. I \0 I!!A~Z~-.". m >< :J:.. -<.. . .f++tH II ···1+++1 I I,~ ,~-++++1 Ie P'O~EFT :DISTRIB:uUTl I ALKEE1N 1 ONFLUEN I .-, I •HOI"'1,.., .+++H- ~-I ..-I..., H _,",_, 'I " " .,1..·,1''''1· +...I+H-1 III '~~~;~Ee~R SUSPENO~D SEDIMEN'r SIZ I eHU'iIT~AI ~IYERI NR.T IIII (UP~~R~AH rhbl.J ~IIE e lUO I I JILLiJ 11110 III .11 IIIII1III11 .• /--+H-t-+t-I·..T-....;-t+t-t 110 III;PART e1 -L.w..t-u H+H-.... ~......... t-..++++t-IHHtI I+t-H·.. --I- ."'0 1 I ;1 1 1 1:;/.I [I trill~~~~~ 20 w t!, '"Q W...« 0 Q Z Z« :J:.... a:wz ~ .... Z W 0a:w.. I~ , ,, I:.••, ""•I".o.•..,.•'0"1,18~,. >; I"± I I I I o c.-z-...~-::m o -0-~ "'WN ::;U)a::""w z r'~a:""C! W W ~,.>0 "c ... ""z-- EXHIBIT 9 ; "- \!!,.:\: • _+.-+-1_'-j"':'"\-'__-+__L..1",>q •J \:; ;\ , .-;-. ..! 0 0 0 0 0 0 I-..'"..~..-0 3ZtS Q3J.VOIONI NVHl t:I3NI~l.N3~t:I3d - , ~_i -.......--~.. ~~,I ;; ~-w ..Z-z \---.--...w ..- - t .-+--'-'-•..j .0:=w ::>w~'m '"...l-..,.Q.- I 0 ..Z,0 ~0- ._--+'-...,'-I-!;-""---"'.;o--+!__'_,1_- 'f·:""'!' _., -, ! ··,•, , • • _.-,...., ...,..I "0 0I0-.... ••, •• •, •• • •• ,••, , I I I I I I E, I I I .J ;j, < o o N o -> I I- -"'. ,,'- ...J ~ j 0 I --ij.Jo.. i ~, o I oo N '-f--'- o " o.. .;-- I 1--'--+"-,I -'";•,j -.. . \ EXHIBIT 10 ~·l:'--- -f-?\.' :_c:o - ---I,. .--'- ..• , 0 0 0 0 "..."'" 3ZIS Q3.l't':)IQNI NVH.1.1:f3NI:I .lN3:>tt3d o..oo .. -,,,"--'~_.--w ","~crtll I -f··_I._.-f-.-01-:;-. ..-..--,.f!2U) I oz I ,~w~;;I r-- a:N'"~I- 0"'< WI-Za:"'w"'::E> 0-'">W-<""'Z I-C"::I "- Z '"l--~-+~-'+:--''"'\.-ti--'~::---tI:-~'-'-+I-~--'--<>:~------1, f---+1--'-----'''''1\1~-+-!;~-li---·~-;;: · · · •• • I , • ··,•• ••.-I 1--' •• •• • •, •• • 1 ,••, 1 •• 1 1 1 1 N I: ~ 1 1 1 II>, 1;..".1t,..'.,.,. "I"0'8:>, 1; I~•>: I I I I ----:~N... <rl EXHIBIT 11 o I-N ", "",:> N.. ---. .-".. t --'-------=3If,,'S:....:O"3"":..V:..O:..'"O"N"',,N.:.V:..H:=!_":..3:..N=..:...:.",,N.:3.:0,,",,3,,d:.. ~,-_.-~I ....< ~•I---_t _00:I- ",-I-'"-,--..!!<,0I,,"Z ,,..I--.;0:-..'"I •~I-0 Z , 0 .. 0:~0:,!Q-O--- •_IlL;: ~-r "a:---- <0 <z.....Z•,,I-0,,;---,i -zl- ----,--"..", !'"i !>~-~-;""",,-.--:>-_. •"'---:-·'"·0 0 ~ ~- I ~-,-, I-f------j -+.~•I ~3-+t·- i --!-~--J - , 0 I "·,-jii;'\,l•,a:.--<·!'\I·I ..· ·~-·]. •.,,-~""--+---t-'--t 1--·I- --+t-~+I ~- •-.----;.-..,.-----;-J \0'·i "")1 I I ;c, ;·--:"]:,,~..~I••, •·I "----I I , •-I--..L -•,-----0 .. 0 0 0 0 0 0 0 0 0 0 I I ,••, I •• I I ••I •, •• I NI: ~ I • I • I Ii,, •1;_••, ~. 0'•I ~l ••• ",.,. "I"!~g I~•>: I I I I '., :' , EXHIBIT 12 '--I- I 1--1, , -_.---'--- --.~-----~I ; ..",_...-II .-J. - - -STAGE I I : l--··i.--t-,. ~~_JfATU.RALCONDITIOr,JS__;'-'-_~__ ; I HARZA-EBASCO SU$ITNA:JOINT VENTURE 600 600 -11;-STAGE m .00 300 ~~"-+--.~-:....-:+··,-··..1 I ---~I;1--". "---'-__--_,,_ ~:.1-. t-I I .;IZ..-T-.•._..-....•: • W I :o -_._--- zoo ....zw.'"-----'_'+-,,--;,--'-- ~---'-1---~l'-:~~!-_...t ._---. ~~_i'_-i __fao_--<-_L_~jl_-.L_h L~:i.;,··_:_I~I f~;,--.~~---- '200:';z !-:I :.--~-:....j ;.r:::':.r-,~ .l!'1!'I;:I :..':I'T..;..t".,...I I- - j :UJ·..........:....·_-1-:.....:.....---.....:...-_....:....!~-_....:..._.--,.::r :i I'•;.:, "---i--'CD f--'- , ,L I'..'I.'. l ..~_~, :100.__c------,-'TT--;-T'"T-~j.....:,._._._.~_ !__~~1-,~_.~_:.~';":.1 '~..-L-.-:1.....-:-.- ::;:-:s-to:..:_-.::::1 ".'--~,~--'-'-::-_._.-. .-I'-,'--. .l--""-'-.-;---<I ••-f--.......:--··l--._.: O I".iiI' ..,I .,;.1--'----;-----:------:-- I . :1.'I"!':,.':I 1.I-:'-r J~·i-t:~aJ;~-R·i ;~±Ai liliN~~~j :;~G:~'~~;~~T·!·~~-~.D~C j -~.-I i ,J'I "0:1 :I ';""1 .:...!!.'i .•~ .;.....•--._~-_.I-~·~1 .------..._.0-1 ·1 ,L,._:'.-_.••_-~---_.---.•SUSTTN""A 'HYDROELECTRIC PROJECT . -SUSITr..lA·RIVER AT GOLD CREEK _._MONTltL't SUSPENDED SEDIMENT.• CONCENTRA TlONS I I I I I I I I I., I I I I I I I I I I "'SUSITNA HYOROEL~CTRIC PROJ(cr -- SUSITNA AIVER AT SUNSHINE MONTHLY SUSPENDED SEDIMEI\T CONCENTRATIONS -'-1,. i-- en'!iBIT 13 f -.I . . :·I-'-=!. .l -,--_._-, i I _.._ ---_.:,;--..,--;- ~-----~--'------ Jut AUG SEP OCT NOV DEC ,,.,., -.- -'r ---0 NATURAl:.CONDITIONS Sr',GE I JAN:FEB MAR APR MAY.JUN HARZA-EBASCO SUSITNA JOINT VENTURE o 500 --.- -,-STAGE m 100 .200.. , 000.-,---_,:,':-'__,-"::E !___._.~_.-1 __-'-_ Z Co l-ea: I-z Woz 400 __~__~,_:! Ii -~-_.1--, -~-"'---i-'--,'--f-+I -+--i----'---f-I 2:.I _-l --1.-,'.-.""---j~,-'----1----'--j---r L3.00_._..~.:-_-I~'<--,i,-.:2.-j .:....__ ,d,.I.;i "-1',._.w--.--r----'-·c -.,-.-"-'---' d'i.'i-.~-:--I 4.___.L co I .:'I--'"iil~1-__-_,;-1.-._.-+-_-1---+-1.-.+:__-.+1 --'-'-1--:"'- ;1-!-----•.---'-.--._...--.--- 1 '-r--'.-.._.·-;-:--1-·,r ._.1 j-' .lOO.,__-'-----i__.:I .i _~l-__;.--._-._..-- I I ...I' r-'~I'-·-1--1'-'~t-.~::-'_.~-_+_+--;-!+-·I·-:I -;--J.it~:1 ;. _ _ _.::,::;t'I ,.-'....--1--'0 .:': ~J1~~:-_._-!'t 'I r--~-I •• ..L ;_,_.=-~.:!.._.~_...l I .j ._~.:.-j.:..j :I 'I .;t :i ..,___1...__.___,' -~------.It:,_-----, I I I I I I I I I I I I •• • I I I I I IIIII I I I I I I I I I I I I I I EXHIBIT 1.NAlU .....L S US~("'OEO 5EO'''E",1CO.U:"',1I~"'"0'"'''OIL)••"••"••"•••:••"••••;:I I 0·-';:•,•::O~mt :::l-'W ,•OCll'",•0'"I .,•, r a:->- It ~,_-'CIl ,•00 ' I ,.•>CIla:,'f)1 0 ,<a:'"·,T.WOW,,CIlW>,,, ,,,,~WO;:,0.,,,a:ZO, , ,1Cl\.,c(~Lt "•ZCIlZ.l:'0 -:r·;.,"':::l -,,=,,">-CIl ,,••'".!'1 •,~,,••;:--<, ,,, , ,•'.I ·-",,•..-••-..<,•"'->-."Z"-'... rfl <H,>r ..,Z•c' 0 .-0•., 0'..,.-,0".. 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"1'llll n/o..,1I011\'lIJ.Nll:lNO::l '"1I'UIII01'OJOII],n"$J,::I]rOIl .."11'":z: •• IIIII I I I I I I I I I I I I I I EXHIBIT 16""tUIIAl.-SU'''UtDEO 'EDIOlf,..tCONCENTIIATIOH(Wall)•••~W••·••,••••••0"..J<•...a:....•....W-,~-::»W•1 0<"·-z <..-0 •a::en ~.--.-•5 ,•-C(l).,·C _ • ~l i .•>..Ja:.a:0<-·•I 1oI~.,W(I)W<(I)~ -.··wc;:·-a::~o'."·<<z..J-..·.-zw'".·J.<a..~,.-·z ....(1)·<><::>·-;:(1)··-•·-·"·>•-<--2 •.-.--·-,.•w.0 •-.-0::<z•"•...-z0- 0 -'w<z· 2 ••>H ...-z 0 do -•~~0".z ~ 1.<1 ~~'"z !~z<..,_. •• r.ttI-••..,~."-..~..-.";.•••0••.-u 0 H .. 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N II:.. :I: EXt4IBIT 18 •<• ~• ••< ••• • 'Z,, ••,- ,I < ,, "•• 110 •••, I III·••Il"Tl,tl'llll 'U"(NOID 'lDllIINTCO"C:UITItATIOIl [MOIL I•8:!~, LII,II'II01S OlOln ..!ns J.:)JrOIl4 "11/11I •• :."f-++~,,j-.~~U..L.4•..L.U..L..!-!..L.U1.fJ..wI..L~•..L..l.l..L..+.J..L..w~.1-' •••4 ..•..0 .. ~~.... .. ~..':~••.. I I III I''I"'i'l I H-1~H-.l i ~~tttH-Irt+t+II+++t+t-H,,:t+I,:.*:l.Ht,+H,*1,in'ItH: I I I I I I I III I I I I I I II I I II EXHIBIT 19 w.. ".. Z W >.. Z o ~.. Z.. '""'"o.., '"....w,.. N.... :z: •••••••••••,·•,N"'TU~"'L JUI'ENDED SEDIMonCOlfCEHTIIAll(lH eNO/UI.I I ·g.··.,•·,,.,••I'-',-, 0· - I •• "· ,•Ilt.- ~of ,"•I ,. I ' ,..',,·.. 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