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PROJECT STATUS REPORT

SHOSHONE / LAKEVIEW 5 WATER DEVELOPMENT PROJECT ....fIl ~ tI) ~ ~ Q ~ fIl o ~ 0 ~ ~ 5 ~~ E---4 fIl _\0 ~~ ~~~ ~~ta r o ~ ~ ~~ ~~:-9~o ~~~~~ SEPTEMBER, 1985

JAMES M. MONTGOMERY, CONSULTING ENGINEERS. INC. JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC.

1301 Vista Avenue Argonaut Building, Suite 210, BOise. Idaho 83705 1(208) 345-5865

1499.0012/13

September 19, 1985

Wyoming Water Development Commission Herschler Building, 3rd Floor, East Wing Cheyenne, WY 82002

Subject: Shoshone/Lakeview Water Development Project

Dear Commission Members:

Presented in this Project Status Report is a work-in-progress summary of the Level II Feasibility Study of the Cody Canal/Lakeview Conveyance System {Lakeview} Project and the Shoshone Municipal Water Supply {Shoshone} Project. The Level II Feasibility Study is intended to provide engineering and economic analyses by which the Cody Canal Irrigation District, Lakeview Irrigation District, Municipal Water Development Association {MWDA}, and Wyoming Water Development Commission can evaluate the merits of the projects and if found feasible, pursue Level m design funding from the Wyoming State Legislature.

It should be noted that the information provided in this Project Status Report is preliminary in nature in that it has not been reviewed in detail by the Wyoming Water Development Commission staff, nor has a complete "in-house" Montgomery Engineers review been conducted. Detailed review has also not been provided by the sponsoring irrigation districts and communities. The Project Status Report is, however, a detailed and comprehensive summary of a preliminary draft Lakeview Level II Report and draft Shoshone Level II Technical Memoranda which has been reviewed by WWDC staff. WWDC/MWDA/Irrigation Districts negotiations and discussions relative to project funding and implementation will be initiated in the near future and final Level II Feasibility Reports completed.

The Project Status Report is divided into three sections:

Section I: Brief Executive Summary of key information on both the Shoshone and Lakeview Projects

PLANNING ... RESEARCH ... ENVIRONMENTAL ENGINEERING JAMES M. MONTGOMERY. CONSULTING ENGINEERS. INC. Argonaut Building, Suite 210, 1301 Vista Avenue, Boise, Idaho 83705, (208) 345-5865

Wyoming Water Development Commissidn- September 19, 1985

Section II: Cody Canal/Lakeview Exchange Project Summary

Section m: Shoshone Municipal Water Supply Project Summary

Respectfully submitted,

JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC. ~i,~.~~~ Project Manager

Daniel P. Wetstein Proj ect Engineer - Shoshone

.6?...... ~1c::a. m -d~1- Dennis M. Suihkonen Proj ect Engineer - Lakeview TABLE OF CONTENTS

Page No.

SECTION I - EXECUTIVE SUMMARY

Executive Summary I-I Lakeview Project 1-2 Project Intent 1-2 Water Demands/Usage 1-2 Crop Irrigation Demand 1-2 Historical Irrigation Water Diversion 1-2 Irrigation System Efficiency 1-2 Water Shortage 1-2 Improvement Requirements for Exchange 1-3 Improvement Costs 1-3 Crop Value Benefit I-3 Benefi t-to-Cost Ratio 1-3 Alternatives to Lakeview Exchange 1-4 Shoshone Municipal Supply Project 1-5 Project Intent 1-5 Water Demands 1-5 Water Storage Requirements 1-5 Winter Pumping Station/Transmission 1-6 Winter Storage 1-6 Buffalo Bill Reservoir (BBR) Diversion/ Conveyance Alternatives 1-6 Option 1 - Shoshone Municipal Supply Only 1-6 Option 2 - Combined Diversion With the Lakeview Exchange; Cody Canal Utilized for Potable Water Supply 1-6 Option 3 - Combined Diversion With the Lakeview Exchange; Cody Canal Not Utilized for Potable Water Supply 1-7 Diversion/Conveyance Cost Estimates 1-7 Water Treatment 1-7 Water Transmission (Treatment Plant to Communities) 1-8 Communities Served 1-8 Capacity and Hydraulics 1-8 Transmission Line Costs 1-8

SECTION n - CODY CANAL/LAKEVIEW EXCHANGE PROJECT

Introduction II-I Lakeview Water Demands II-2 Water Rights and Supply II-6 Water Rights II-6 Other Water Rights II-6 Water Supply II-7 Estimated Lakeview Water Shortage II-7 TABLE OF CONTENTS (continued)

Page No.

Exchange Improvements II-7 Cost Analysis II-8 Crop Value Analysis II-8 Exchange Improvement Costs II-9 Capital Costs II-9 Operation & Maintenance Costs II-I 2 Benefit to Cost Ratio II-I 2 Lakeview Irrigation District Upgrade Costs II-I 5

SECTION m - SHOSHONE MUNICIPAL SUPPLY PROJECT

Introduction m-I Water Supply Alternatives During Shoshone Conduit Shutdown m-I Winter Supply Options m-I Water Demands m-I Storage Requirements m-2 Buffalo Bill Reservoir Diversion/ Conveyance Alternatives m-3 Option I - Shoshone Municipal Supply Only m-3 Option 2 - Combined Diversion With the Lakeview Exchange; Cody Canal Utilized for Potable Water Supply m-3 Option 3 - Combined Diversion With the Lakeview Exchange; Cody Canal Not Utilized for Potable Water Supply m-4 Winter Pumping Station and Transmission Line ill-4 Downstream Winter Storage m-4 Hydrogeology/Water Quality ill-5 Future Operations m-6 Project Cost Estimates m-6 Buffalo Bill Reservoir Diversion m-6 Option I - Shoshone Municipal Supply Only m-6 Option 2 - Combined Diversion; Cody Canal Utilized for Potable Water Supply ill-7 Option 3 - Combined Diversion; Cody Canal Not Utilized for Potable Water Supply ill-7 Winter Pumping Station & Transmission Line m-7 Downstream Winter Storage ill-7 Summary and Recommendations m-7 BBR Diversion ill-7 Winter Supply ill-I 3 Water Treatment m-I3 Treatment Process m-I3 Recommendations of the Update Study ill-I 3 THM and Taste/Odor Control m-I4 Summary Process Recommendations m-I4 TABLE OF CONTENTS (continued)

Page No.

Use of Existing Treatment Plant m-I4 Siting m-I8 Plant Layout m-I8 Phasing and Cost Construction of Project m-I8 Summary and Recommendations m-zo Transmission Pipeline m-zo Communities Served and Alignment m-zo Capacity and Hydraulics m-zz Appurtenances m-zz Transmission Pipeline Cost Estimate m-Z3 LIST OF TABLES

Table No. Page No.

CODY CANAL/LAKEVIEW EXCHANGE PROJECT

I Calculated Lakeview Consumptive Use and Demand Neglecting Precipitation II-3 2 Calculated Lakeview Irrigation Requirement and Demand Considering Precipitation II-4 3 Range of Historical Lakeview Diversions II-S 4 Lakeview Water Rights II-6 S Value of Lakeview Irrigation District Production & Unrealized Potential Production II-I 0 6 The Value of Increased Production on the Lakeview Irrigation District with an Enhanced Water Supply II-II 7 Exchange Improvement Costs II-I 3 8 Exchange Improvements Annualized Cost II-I4

SHOSHONE MUNICIPAL SUPPLY PROJECT

1 Shoshone Municipal Supply Project Estimated Water Demands m-I 2 Shoshone Municipal Supply Winter Water Storage Requirements m-3 3 Option 1 - BBR Diversion Project Development Cost Estimate m-8 4 Option 2 - BBR Diversion Project Development Cost Estimate m-9 S Option 3 - BBR Diversion Project Development Cost Estimate m-IO 6 Winter Pumping Station & Transmission Line Project Development Cost Estimate m-Il 7 Downstream Winter Storage Project Development Cost Estimate m-I2 8 Cody Regional Treatment Plant Design Criteria m-IS 9 Cost Estimate Comparison Single Plant Versus Two Plant (Initial Construction) m-19 10 Cost Estimate for Initial Construction of Cody Regional Water Treatment Plant m-2I 11 Transmission Pipeline Cost Estimate m-24 LIST OF FIGURES

Following Figure No. Page No.

CODY CANAL/LAKEVIEW EXCHANGE PROJECT

1 Exchange Agreement Schematic IT-I 2 South Fork Shoshone River Hydrographs IT-7 3 Estimated Lakeview Shortage at Mean Supply Condition IT-7 4 Estimated Lakeview Shortage at 80% Supply Condition IT-7 5 Conveyance Pipeline Plan and Profile IT-7 6 Cody Canal Facilities IT-8 7 Typical Gate-Type Check Structure IT-8

SHOSHONE MUNICIPAL SUPPLY PROJECT

1 Seasonal Fluctuation in Domestic Water Demand for the City of Cody ID-2 2 Omitted 3 BBR Diversion Option 1 ID-3 4 BBR Diversion Option 2 ID-4 5 BBR Diversion Option 3 ID-4 6 Winter Supply Pumping Station and Transmission Line ID-4 7 Winter Pumping Station Schematic ID-4 8 Winter Storage System ID-5 9 Process Schematic/Hydraulic Profile for Shoshone Supply Regional Water Treatment Plant ID-14 10 Area Plan of Existing and Proposed Water Treatment Facilities ID-19 11 Site Plan for Shoshone Supply Regional Water Treatment Plant ID-19 12 Project Phasing Plan for Shoshone Supply Regional Water Treatment Plant ID-20 13 Proposed Shoshone Municipal Pipeline Corridor ID-21

EXECUTIVE SUMMARY

This Executive Summary is intended to provide the reviewer with a brief overview of key project considerations and information for both the Lakeview Project and Shoshone Projects. More detailed Lakeview and Shoshone evaluations are provided in Sections II and m, respectively.

I-I LAKEVIEW PROJECT

PROJECT INTENT

The Lakeview Irrigation District has indicated it is periodically unable to divert sufficient water for irrigation of crops from the South Fork of the Shoshone River during the critical irrigation months of July and August. The shortage of water is primarily due to other users holding water rights senior to those of the Lakeview Irrigation. District on the South Fork, and lack of sufficient supply for all users during critical use periods. In drought years, the problem is more severe to the point of causing crop damage and economic loss. As a result of this situations, an exchange agreement has been proposed between the Lakeview Irrigation District and the downstream Cody Canal Irrigation District whereby Lakeview would divert up to 100 cfs additional water from the South Fork during water short periods, and the Cody Canal Irrigation District in turn would divert up to 100 cfs from Buffalo Bill Reservoir instead of diverting that incremental quantity from the South Fork of the Shoshone River. The maximum amount of water that could be annually diverted would be 10,000 acre-feet.

WATER DEMANDS/USAGE

Crop Irrigation Demand

Theoretical crop irrigation demand based on actual 1983 cropping pattern ranges from 65 to 135 cfs on a biweekly basis during the peak consumptive use months of July and August.

Historical Irrigation Water Diversion

Based on 15 years of record from 1965 through 1982, the actual Lakeview water diversion has ranged from an extreme low of 135 cfs to an extreme high of 290 cfs on a biweekly basis during July and August. Mean diversions have ranged from 192 cfs to 238 cfs for the same period.

On an annual basis, irrigation water diversions have averaged 5.3 acre-feet per acre with peak usage up to 6.0 acre-feet per acre.

Irrigation System Efficiency

WATER SHORTAGE

During mean South Fork Shoshone River water supply conditions, Lakeview appears to have a shortage of up to 50 cfs during the critical irrigation period. Up to 20 percent of the time (2 years out of 10), Lakeview will have a water shortage of up to 95 cfs during the critical irrigation period. As a result, even with the 100 cfs exchange, Lakeview would still experience insufficient supply to meet average historical diversions at a frequency level of less than 20 percent.

1-2 IMPROVEMENT REQUIREMENTS FOR EXCHANGE

The improvement requirements to implement the exchange consist primarily of:

• Diversion at Shoshone Conduit trifurcation structure approximately three miles west of Cody.

• 48-inch diameter pipeline (sized for common conveyance with Shoshone municipal water supply) and 36-inch diameter pipeline to the Cody Canal near Sulphur Creek.

• Four new check structures and replacement of eleven existing check structures in the Cody Canal between the South Fork diversion and Sulphur Creek.

• Level control structures for six existing diversions along the South Fork of the Shoshone River.

IMPROVEMENT COSTS

The total estimated Lakeview project costs are $3,512,000. This takes into consideration the Shoshone Project paying for its share of the common conveyance pipeline from the Shoshone Conduit to Sulphur Creek. Total annual costs (based on 4, 6 and 8 percent interest over 50 years, and including annual operation and maintenance costs) are $178,000, $238,000 and $302,000, respectively.

CROP VALUE BENEFIT

Based on three cropping patterns most likely to be used within the District, the value of increased annual production as a result of the exchange ranges from $217,200 to $277,400 per year. The $217,200 figure is for the actual 1983 cropping pattern.

BENEFIT-TQ-COST RATIO

For the three cropping patterns at the 4, 6, and 8 percent interest rates, the benefit-to-cost ratios for the project are as follows:

Benefit/Cost Ratios @ Various Interest Rates Crop Combination 4% 6% 8%

No. 1 1.22 0.91 0.72 No.2 1.56 1.16 0.92 No.3 1.30 0.97 0.76

The benefit-to-cost ratios would of course be higher if only the Lakeview funded portion of capital costs were considered. It is anticipated that Lakeview would fund from 25 to 50 percent of capital costs.

1-3 ALTERNATIVES TO LAKEVIEW EXCHANGE

A potential alternative to obtaining additional water through an exchange agreement would be to upgrade the efficiency of the existing Lakeview conveyance and field application systems.

The Soil Conservation Service (SCS) evaluated the Lakeview Canal system in 1983 and recommended a significant list of improvements to be made over a 40 year period. Most of the improvements are related to replacing existing structures and maintaining the present system rather than specifically increasing the efficiency of the canal system (although some efficiency increase would result). In addition, there were some specific areas pointed out in the report where system efficiency could be improved.

It was suggested that approximately 3500 acres in the Irma Flats areas could be converted to sprinkler irrigation increasing field application efficiency by 20 percent with an average annual savings of 3560 acre-feet (10 cfs average flow). The SCS construction cost estimate (1983) to install the pipelines and sprinkler system was $1,182,000. Adding 50 percent for contingency, engineering, financing, legal, and inflation, the 1985 cost would be $1,773,000. Thus, the cost per acre-foot to convert some acreage to sprinkler application would be $500 per acre-foot versus $350 per acre-foot for exchange agreement water.

Another potential area for significant water conservation would be to control seepage in the canal which is estimated at 100 cfs at full flow conditions (270 cfs:) in the SCS report. One canal reach of approximately 4.2 miles has been estimated to lose approximately 16 percent of the flow. At an average annual Lakeview flow of 137, cfs that would amount to approximately 7800 acre feet annually (22 cfs average flow). An approximate cost to line the canal and prevent seepage would be $70 per foot for PVC lining overlain by 10-inches of native fine soil and 8-inches of pitrun gravel. Estimated service life would be 30-50 years. Thus, the construction cost would be $1,552,000 for a 4.2 mile reach. Adding for contingency, engineering, etc., the total project cost (1985) would be $2,142,000. The cost per acre-foot would be approximately $275 per acre foot.

Prelimiminary estimates of increasing system efficiency through sprinkler application or canal lining in those areas mentioned above would appear to indicate that conversion to sprinkler application systems would be more expensive than exchange water. However, canal lining of high loss area may be a cost-effective alternative to exchange implementation.

I-4 SHOSHONE MUNICIPAL SUPPLY PROJECT

PROJECT INTENT

The Shoshone-Municipal Supply Project was initiated as a regional water supply alternative to provide a dependable {quality and quantity} water source for the communities of Cody, Lovell, Powell, Byron, Cowley, Deaver and Frannie. At this time it appears that most likely Cowley, Frannie and Deaver will be served by a ground water supply separate from the Shoshone Project. This Executive Summary provides a brief description of key Shoshone Project components and estimated costs.

WATER DEMANDS

The estimated water demands for the Shoshone Municipal Supply Project are presented below.

SHOSHONE MUNICIPAL SUPPLY PROJECT ESTIMATED WATER DEMANDS

Average Daily Peak Daily Flow Flow Year (mgd) (mgd)

1990 3.6 8.8 2000 4.3 12.2 2010 5.1 15.5 2020 5.7 18.7 2030 6.5 22.0

WATER STORAGE REQumEMENTS

Because the Shoshone Conduit has up to a 12-week winter shutdown period for maintenance, water supply for the Shoshone Project must be provided from storage or by other means during the shutdown period. The storage requirements are as tabulated below:

SHOSHONE MUNICIPAL SUPPLY WINTER WATER STORAGE REQUIREMENTS

Average Winter Net Storage Gross Storage Daily Demand Year (mgd) (MG) (Ae-ft) (MG) (Ae-ft)

1990 2.9 244 768 272 853 2000 3.5 291 913 323 1014 2010 4.0 339 1063 376 1181 2020 4.6 384 1206 427 1340 2030 5.2 433 1361 482 1513

1-5 An alternative to storage to meet water demands during Shoshone Conduit shutdown would be direct pumping from the Shoshone River.

Winter Pumping Station/Transmission

The pump station would be located on the east bank of the Shoshone River near the DeMaris Springs crossing. A 16-inch diameter transmission line would connect the pump station to the Shoshone Municipal Supply main at a point just west of Sulphur Creek. The total estimated winter pumping station/transmission system cost would be $3,224,000.

Winter Storage

The winter storage alternative would consist of enlargement of the existing City of Cody storage system. The enlargement would consist of raising the Beck Lake dam, connecting Beck and Alkali Lakes, installing a new inlet into the reservoirs and dredging each of the impoundments to remove sediment and organic material accumulations, and restore original capacities. Between the maximum and minimum levels the combined volumes of Beck and Alkali Lakes is approximately 1260 ac-ft. The usable storage in Markham and New Cody Reservoirs is 67 and 508 ac-ft, respectively. Therefore, a total working volume of 1835 ac-ft would be made available for winter storage, an amount which is well in excess of the 1513 ac-ft required for a 12-week period in the year 2030.

The total estimated cost for enlargement of the City of Cody storage system for required Shoshone Project winter storage would be $5,257,000.

BUFFALO Bn.L RESERVOm (BBR) DIVERSION/CONVEYANCE ALTERNATIVES

Three conveyance alternatives were evaluated for either a combined Shoshone/Lakeview Project, or for an independent Shoshone Supply Project. The diversion/conveyance alternatives are:

• Shoshone Municipal Supply only.

• Combined Shoshone/Lakeview Projects supply with the use of the Cody Canal for potable water supply.

• Combined Shoshone/Lakeview Projects supply without the use of the Cody Canal for potable water supply.

Option 1 - Shoshone Municipal Supply Only

Should the Lakeview Exchange Project not prove viable, then water would be supplied to the Shoshone Municipal Project in a pipeline sized for the peak day demand for the planning period; 22.0 mgd. A 30-inch diameter pipeline would satisfactorily convey this flow to the water treatment plant.

Option Z - Combined. Diversion With the Lakeview Exchange; Cody Canal Utilized for Potable Water Supply

During the irrigation season the combined flows of the Lakeview Exchange Project (100 cfs max.) and the Shoshone Municipal Supply would be diverted from

I-6 the Trifurcation Structure and ·carried in a common conveyance to the Cody Canal. Water would be withdrawn from the canal for treatment and distribution to the Shoshone Municipal Supply.

During the periods when the Cody Canal is not in use, water would be transmitted to the treatment plant in a smaller pipeline which branches off from the combined conveyance on the west bank of Sulphur Creek Canyon. The corn bined flow pipeline would be 48-inches in diameter, while the smaller branch line would be an 18-inch diameter pipeline.

Option 3 - Combined Diversion With the Lakeview Exchange; Cody Canal Not Utilized for Potable Water Supply

This alternate was developed to assess the extra cost associated with preventing the water losses and quality degradation that occur when the Shoshone Municipal Supply is carried part of the way in the Cody Canal (Option 2). Water withdrawn from the Canal is of lower quality than that taken directly from BBR, primarily because of irrigation return flows and surface runoff. The Cody Canal is also a much less efficient means of transport than an enclosed pipeline; therefore, water losses from the Canal are to be expected.

As with Option 2, the combined flow section of the transmission line would be sized for a peak daily flow of about 134 cfs and would be 48 inches in diameter. The branch main would be sized for a maximum flow of 22.0 mgd (34.0 cfs) and would be a combination of 30- and 36-inch diameter pipe.

Diversion/Conveyance Cost Estimates

The estimated total project costs for the three Buffalo Bill Reservoir diversion/conveyance alternatives are:

Option 1 $4,063 , 000

Option 2 $3 ,346 ,000

Option 3 $4,279,000

If the Lakeview Exchange is implemented, Option 2 is less costly than Option 3 by approximately $930,000. However, Option 3, which provides BBR water directly to the Shoshone Supply year-round, has many operational advantages over Option 2. Chief among these advantages are higher delivered water quality and much less transmission loss. In addition, the lower cost of Option 2 will be offset by additional treatment requirements. Therefore, Option 3 is the recommended system for a com bined Lakeview/Shoshone Proj ect conveyance.

WATER TREATMENT

It is recommended that a single new regional water treatment plant at Cody be constructed at an initial capacity of 16.5 mgd and be expandable to 22.0 mgd. The total estimated project cost would be $14,229,000.

An alternative would be to construct a plant with an initial 11.0 mgd capacity, with future expansions to 16.5 mgd and finally, 22.0 mgd. The total estimated project cost for an 11.0 mgd plant would be $11,916,000.

1-7 WATER TRANSMISSION (TREATMENT PLANT TO COMMUNITIES)

Communities Served

The treated water pipeline was originally proposed to serve Cody, Powell, Byron, Cowley, Frannie, Deaver, Lovell and rural areas along the pipeline alignment. However, Cowley has recently drilled a new well with excess capacity Byron is currently connecting to that source. In addition, Frannie and Deaver are currently engaged in jointly drilling a new well to serve those communities. It is uncertain what future course of action those communities may take. At this time, the only community which has expressed a desire not to be considered for the Shoshone project is Cowley. Therefore, for the purposes of this report it is assumed the transmission pipeline will be sized for all communities along the alignment men tioned above, excluding Cowley.

Capacity and Hydraulics

The pipeline is sized {24-inch maximum line size} to meet the maximum demand in the year 2030 for the communities indicated above. The selected alignment allows gravity flow from an elevation of 5100 at the clearwell of the proposed water treatment plant in Cody to El 3855 in Lovell. It was determined that one pressure reducing station would be needed just upstream of Powell to maintain pipeline pressures under 300 psi at static conditions. The pipeline was sized and hydraulic gradeline generally set to maintain a delivery pressure of 40 to 45 psi to communities along the route.

Transmission Line Costs

The total estimated project cost for the transmission line is $19,404,000. Pipeline costs include extension to Powell and 5,000 feet of 8-inch pipe to rural communities, but do not include extension to Frannie and Deaver, or outlying areas a significant distance from the transmission pipeline.

1-8

CODY CANAL/LAKEVIEW EXCHANGE PROJECT CODY CANAL/LAKEVIEW EXCHANGE PROJECT

INTRODUCTION

An exchange agreement has been proposed between the Lakeview Irrigation Dis trict and the downstream Cody Canal Irrigation District whereby Lakeview would divert up to 100 cfs additional water from the South Fork during water short periods, and the Cody Canal Irrigation District in turn would divert up to 100 cfs from Buffalo Bill Reservoir instead of diverting that incremental quant ity from the South Fork of the Shoshone River. The maximum amount of water that could be annually diverted would be 10,000 acre-feet. The exchange agree ment would effect the current operation of the Cody Canal system as well as requiring additional conveyance facilities to deliver water from Buffalo Bill Reservoir to the Cody Canal. A schematic of the proposed exchange and loca tion of points of diversion is shown on Figure 1.

The purpose of the study is to determine the technical and economical feasibility of the Lakeview-Cody exchange and to compare the benefits of the exchange versus the additional facility and operation and maintenance costs incurred as a result of the exchange. Should the project be technically and economically feasible, and supported by the effected parties and the WWDC, recommendations are to be made for implementation.

The key aspects of the study are listed below, with discussion following:

• Determine Lakeview Water Demand

• Evaluate Availability of Water Supply and Water Rights Issues

An estimate of Lakeview water shortages will be quantified based on projected demands and water supply availabilities.

• Evaluate and Identify Needed Improvements as a Result of the Ex change

This includes facilities for conveyance of exchange water from Buffalo Bill Reservoir to Cody Canal as well as improvement require ments to Cody Canal itself.

• Perform an Economic Analysis and Comparison of the Cost of the Exchange Versus Resultant Benefits.

To understand the following analysis, a few definitions are necessary regarding the use of such terms as consumptive use, irrigation requirement, and irrigation demand. The consumptive use of a crop is defined as the quantity of water

II-I '. , :~ j I 1', ~ _ ....,' .... /, /-

1 1 I I Bcate- - - 11)119- ·'v I \ \ ~ '" \\., . ! USGS ,GA(3JNG . / STATIONx66281000 '/ i. \ >. UP TO 100 CFS L~SS DIV9RTED, AT CODY CANAL tNT'AKE /

':UP T 100 CFS·, DIVER'TEOT~ ,', ' LAKEVIEW CAN~l ,::;,~\ ~,' ,; /~ 0:''-

-:-. (

EXCHANGE AGREEMENT SCHEMATIC FIGURE 1 absorbed by a crop and transpired or used directly in the building of plant tissue together with that evaporated from the crop producing land. Irrigation require ment is the quantity of irrigation water necessary to replace the soil moisture which has been consumptively used by growing crops, less precipitation. The irrigation demand is the quantity of irrigation water requested or diverted at the headgate to satisfy a field irrigation requirement. Irrigation demand includes water losses which exist due to conveyance seepage and leakage and field ap plication inefficiencies.

LAKEVIEW WATER DEMANDS

The Lakeview Irrigation District shown on Figure 1 encompasses 9425 acres. An analysis was performed to determine the maximum anticipated irrigable acres. Allowing for roads, residences, steep slopes, canal right-of-way, unusable land, etc. it was estimated that 9167 acres of the total 9425 acres are currently irrigated.

Although a number of different cropping patterns were evaluated for water de mand requirements, the actual 1983 cropping pattern was utilized to project water demand requirements since its associated demand was slightly higher than any of the other cropping patterns. The 1983 cropping pattern is summarized below and its consumptive use requirement is presented in Table 1.

1983 Crop % of Acreage Planted

Alfalfa 65.6 Corn 0.5 Pasture 20.9 Potatoes 0.2 Spring Grain 12.8

100.0

Taking precipitation into account, consumptive use is reduced by the recorded average amount of precipitation and is shown in Table 2. Water needs begin to rise in April and taper off in October. The maximum amount of water ideally needed for healthy crop growth neglecting application and conveyance losses ranges from 65-135 cfs during the months of July and August.

Based on 15 years of record from 1965 through 1982, Table 3 was developed which shows the historical Lakeview water diversions at various levels of prob abilities of occurrence. As can be seen from Table 3, the peak diversion period is during July and August.

It is estimated the overall efficiency of application and conveyance systems for the Lakeview Irrigation District is approximately 32 percent. That is, 32 percent of water diverted from the South Fork of the Shoshone River actually contri butes to consumptive use for crop growth. Approximately 68 percent of diverted water is not utilized due to conveyance losses or field application inefficiencies.

It appears a significant amount of water could be saved by converting more irrigated acreage to sprinkler application systems, as well as reduction of canal

II-2 TABLE 1

CALCULATED LAKEVIEW CONSUMPTIVE USE AND DEMAND NEGLECTING PRECIPITATION

(Summary of the Lakeview Irrigation District's calculated demand. Precipitation is not considered in this data.)

Calculated1 CalculatedZ 1983 Demand 1983 ET Period (30-Years) (30-Years) Biweekly #Z #3 Records Ac.Ft./period Ac.Ft./period

4-13 0 0 4-2 0 91

5-1 528 1068 5-2 1583 2259

6-1 2102 2446 6-2 2794 2180

7-1 2193 3083 7-2 4200 3487

8-1 2251 2829 8-2 1975 1675

9-1 1972 1806 9-2 1972 1500

10-1 0 1305 10-2 0 1

Annual ZI,570 Acre-Ft Z3,730 Acre-Ft

1. The irrigator determines the historical demand and assumptions about the soil, season, and crops produce the calculated demand. These values are from a water balance routine (at 100% efficiency) and assumes a soil mois ture holding capacity of 1.8 inches per foot and a 3.0 foot depth of soil and the 1983 crop distribution.

2. ET means evapotranspiration and is the quantity of water the crops will withdraw from the soil. ET requirements must be satisfied daily where irrigation demand must be satisfied on the date of irrigation. Deficit irri gation implies that total ET is greater than total demand and soil moisture storage makes up the difference.

3. 4-1 indicates first half of month of April, 4-2 indicates second half of month-of April.

TI-3 TABLE 2

CALCULATED LAKEVIEW mRIGATION REQumEMENT AND DEMAND CONSIDERING PRECIPITATION

(Precipitation and its effect on the Lakeview irrigation requirement and project demand, with the crop distribution of 1983.)

Calculated Reduced Effective1 Irrigation Calculated Precipitation Requirement Demand Period (30-Years) (30-Years) (3D-years) Biweekly #1 #2 #3 Records Ac.Ft./period Ac.Ft./period Ac.Ft./period

4-1 0 0 0 4-2 52 39 0

5-1 203 865 325 5-2 357 1902 1226

6-1 519 1946 1583 6-2 519 1661 2275

7-1 267 2816 1926 7-2 267 3220 3933

8-1 183 2646 2068 8-2 176 1499 1799

9-1 196 1610 1776 9-2 196 1304 1776

10-1 93 1212 0 10-2 71 (o) 0

Annual 3,100 Acre-Ft 20,720 Acre-Ft 18,687 Acre-Ft

1. From F AO-Be analysis of 30 year precipitation records with April through October effective precipitation of 0.89, 0.94, 1.36, 0.70, 0.48, 0.59, and 0.28 inches. Assume dormant season precipitation only fills soil reservoir and is not used consumptively.

II-4 TABLE 3

RANGE OF mSTORICAL LAKEVIEW DIVERSIONS

(Extreme, high (80%) mean (50%), and low (20%) probability levels of observed bimonthly Lakeview project irrigation demand. These are mean flow values from fifteen years of record. 1 )

High2 Low2 High3 Low3 Mean Period Value Value Probability Probability Value Biweekly (Extreme) (Extreme) (80%) (20%) (50%) Records cfs cfs cfs cfs cfs

4-1 23.0 0.0 7.1 (0.0) 2.0 4-2 87.3 0.0 39.6 (0.0) 16.7

5-1 174.6 0.0 121.3 28.6 74.9 5-2 232.5 79.1 200.1 119.4 159.7

6-1 280.1 132.9 250.7 180.3 215.5 6-2 313.6 99.6 275.0 177.5 226.2

7-1 262.0 186.4 245.2 205.6 225.4 7-2 290.8 203.9 258.5 218.3 238.4

8-1 265.6 162.5 249.2 202.2 225.7 8-2 250.2 134.8 220.8 162.4 191.6

9-1 225.8 106.1 188.0 128.2 158.1 9-2 183.0 64.1 152.3 90.9 121.6

10-1 178.3 0.0 99.4 (0.0) 47.8 10-2 38.1 0.0 16.4 (0.0) 5.7

Annual 153.9 113.1 145.9 127.4 136.6

1. The values are non-exceedance values from 1965 through 1982 excluding 1965, 1973, and 1977.

2. These values are based on the assumption of uniform flow in bimonthly periods. There may have been days when the highs and lows surpassed the indicated extremes.

3. ( ) indicates greater than 20% occurrence.

II-5 leakage. Approximately 3500 acres appear to be conducive to gravity sprinkler systems which would raise overall system application efficiency to over 50 per cent with a net savings of approximately 3560 acre-feet (10 cfs average flow). There is a reported 16 percent seepage loss between canal stations 195+50 and 418+80 which could be eliminated by lining that portion of the canal. That would result in a savings of 48 cfs at maximum flow. There are probably other areas such as metering and record keeping which should be investigated to improve system efficiencies. It appears at least 30-50 cfs average flow (50-100 cfs at maximum flow) could potentially be saved through a program of internal system improvements.

In an average year, the Lakeview Irrigation District diverts approximately 5.3 feet of water per irrigable acre and has diverted up to 6 feet per acre in some years, which is a comparatively high water demand.

WATER RIGHTS AND SUPPLY

By determining the amount and probability of supply available to the Lakeview Irrigation District (based on historical South Fork water flow rates and water rights constraints) versus the previously established water demands, an esteimate of water shortage and probability of occurrence can be determined.

WATER RIGHTS

The Lakeview Irrigation District water rights are summarized in Table 4. Since the maximum estimated acreage to be irrigated for the Lakeview Irrigation Dis trict is approximately 9167 acres, it is apparent that sufficient rights are on record for the approximate total estimated irrigable acreage at one cfs per 70 acres allowable. Of Lakeview's 133.36 cfs total water rights, approximately 122 cfs are recorded prior to June, 1903. Other basin water rights prior to June, 1903 total 199 cfs with most belonging to the Cody Canal Irrigation District (154 cfs).

TABLE 4

LAKEVIEW WATER RIGHTS

Ditch Permit No. Date cfs

Hammitt Canal 3000-10,512 12/31/1900 88.84 Enlarged Shoshone Canal 1024E 4/16/1903 33.31 Enlarged Hammitt Canal 2624E 11/5/1910 0.57 Enlarged Hammitt Canal 2414E 4/25/1911 10.55* Enlarged Hammitt Canal 6093E 7/17/1963 0.09

TOTAL 133.36

*Includes a supplemental water right of 3.09 cfs.

OTHER WATER RIGHTS

Lakeview Irrigation District and Cody Canal Irrigation District have the largest percentage of recorded water rights in the South Fork Shoshone basin. Cody

II-6 Canal Irrigation District has a recorded right of approximately 180 cfs. Thus, the two districts combined control approximately 313 cfs recorded right out of the 380 total basin water right.

WATER SUPPLY

Based on an evaluation of U.S. Geological Survey gaging station data on the South Fork of the Shoshone River, a hydrograph of total mean monthly river flow near the Cody Canal diversion was developed and is as shown on Figure 2. It is apparent that sufficient supply is normally available to meet the total South Fork Shoshone basin water right of at least 380 cfs (at one cfs per 70 acres) from May 1 to September 1.

ESTIMATED LAKEVIEW WATER SHORTAGE

The estimated Lakeview shortage can be approximated by plotting all basin water demands on the basin supply hydrograph and graphically measuring the difference in supply and demand. A graphical analysis of the estimated shortage during mean supply conditions is shown on Figure 3. As can be seen from the graph, the Lakeview Irrigation District appears to have a shortage up to approxi mately 50 cfs during the critical irrigation period of an average water supply year.

In addition to mean basin runoff, hydrographs were projected for 80 percent and 100 percent levels of supply probability for the lower gaging station. Those hydrographs are shown on Figure 4. The 80 percent probability curve indicates that approximately 8 years out of 10 that amount of supply indicated will be available. Plotting other water rights and Lakeview requirements on the 80 percent supply curve indicates that approximately 20 percent of the time or two years out of ten, the Lakeview Irrigation District will be short up to approxi mately 95 cfs during the critical irrigation period.

From the above supply and demand estimates, it appears that a flow up to 100 cfs is a reasonable amount and would satisfy Lakeview's average requirement at least 8 out of 10 water years. However, it would not assure that Lakeview would always have sufficient water. Approximately two years out of ten, Lakeview, as well as other water users, would still experience insufficient supply to meet average historical withdrawals.

EXCHANGElMPROVEMENTS

Based on a previous evaluation of alternatives of diverting water from the Buffalo Bill Reservoir, the combined irrigation water exchange and municipal water supply line as shown on Figure 5 was selected. Water would be diverted from the existing Shoshone Conduit trifurcation structure located on the south bank of the canyon mouth approximately three miles west of Cody. The trifur cation structure was constructed with three diversion ports; two are currently in use and the third port available for use by this project. The diverted flow would be metered at the trifurcation structure and delivered by pipeline to the Cody Canal near the existing canal bypass tunnel as shown.

The amount of flow required for the exchange would vary from zero to a maxi mum of 100 cfs (65.2 mgd) and could be needed from April to October. The peak

II-7 2500 1"""\ / \ LEGEND I \ UPPER BASIN GAGING STATION 06280300 I \ LOWER BASIN GAGING STATION 06281000 2000 I \ I \ LOWER BASIN GAGING STATION 06281000 I \ I \ _ 1500 rn i ~ PROJECTED TOTAL SO. FORK SHOSHONE olL i \ BASIN RUNOFF ABOVE BUFFALO BILL ~ 1 \ \ RESERVOIR EXCLUDING IRRIGATION USE ~ o I" : AND RETURN FLOWS ..J lL 1000 , f \ z « I i \ w ~ I i \ Ii \ I; \ ACTUAL RECORDED RUNOFF 500 I : : \ I ..! :.. INCLUDING IRRIGATION USE I. \ AND RETURN FLOWS ~ \ .. -... -...... 0 It) v It) It) It) It) It) It) 10 10 It) It) It) or- or- or- or- or- or- or- or- or- or- or- or- or- z m a: a: >- z ..J CJ 0- .... > 0 z « w « 0- « :l :l :l W 0 0 w « ~ lL ~ « ~ ~ ~ « rn 0 z 0 ~

SOUTH FORK SHOSHONE RIVER HYDROGRAPHS FIGURE 2 2500

2250

ex: o ~ 2000 w en w ex: MEAN SUPPLY AVAILABLE (50% PROBABILITY OF OCCURRENCE) ..J ..J 1750 CD o ..J < ~ 1500 ::l £ll ex: < ~ 1250 en CRITICAL CROP - GROWTH PERIOD LLo -LL 1000 oLa. Z EXTRA PROPORTIONAL ::l ex: LID SHARE OF SUPPLY Z 750 en < £ll

~ a: 500 ADDITIONAL AVERAGE [ o LID HISTORICAL USE LL ABOVE 1 CFS/70 ACRES t------...... LID SHORTAGE VARIES :I: 0-50 CFS IN SHADED AREA ~ ::l o 250 en j ALl. USERS INITIAL SHARE AT 1 CFS/70 ACRES ==380 CFS

o~------~------,.. ,.. ,..__ ----__,.. --~--__,.. ------~------~----,.. ,.. ___,.. a: 0.. ~ :> 0.. W o o < en o z

ESTJMA TED LAKEVIEW SHORTAGE A T MEAN SUPPL Y CONO-ITION FIGURE 3 1250

80% OF SUPPLY AVAILABLE (80" PROBABILITY OF OCCURRENCE)

1000 CRITICAL CROP GROWTH PERIOD

100% OF SUPPLY AVAILABLE EXTRA PROPORTIONAL LID SHARE OF 80" SUPPLY

ADDITIONAL AVERAGE LID HiTORICAL USE \ LID SHORTAGE VARIES REMAINING RIGHTS'" 0 0-96 CFS IN SHADED AREA AFTER 12/31/1900:r; 250

ESTIMA TED LAKEVIEW SHORTAGE A T 80% SUPPL Y CONDITION FIGURE 4 u - 5243.8 5240--~·~~\~~~_~~------447.88~__~r------T------'------~------~------~------~~m~----'------~------·~------l

W \ r ------HYOR~UL N ~ \ ~~AO > .... ~ -~~~ ~ g ~ 5200 - / A~. ...:; ---:~!I~"'.\----_t------I_------I_------_t5~2~1~0~!~~1'~~\GO~-~~:t~~---l~~::![t=°f~======~~~~j')~------I!r1~r---1u.; \ // ,,~IS' 48- (~(W) z : Z I / "-(q" ~ ~ c( .... o / ...... G Q, .. 10 0 ~ ~ 1\ / '''''~O~ I 7;~36- ~ ~ (/J 00::: \ / -~~¢ -... -41'~ :I: 0 ~ 5160----~~~----+_------~------~------_rr_------1_------_+~~1~~~~~~----+?~~--_r------~--____~~~rlH~nl~O----~ a~ ~ '\ " "1/ --.-.- ---...... -1' .~~__ 514 9.0! .- '\... I u __ 5143.5t ~ '-,- / ~-~. I ~ 5120----~~----~--~~------~------~---~/--+_------~------_+------~------+_------_r------~-\;\~._--~.~r-----~ w '\ /"- / \ffi ~ r'\./ " I \ ~ --~-r-_J \ 0 \~ / 5080----~~-----+_------~------~------~------~------_+------~------+_------~------~--~~~~------~ \.:i;:) J! ,(/J./ V 0+00 10tOO 20tOO 30+-00 40+-00 50+-00 60+00 70tOO 80tOO 90+-00 100+-00 110tOO 120tOO CONVEYANCE PIPELINE PLAN AND PROFILE FIGURE 5 future municipal water supply requirement will be approximately 22 mgd which would also occur during the summer months. The municipal supply is proposed to provide a potable water source for the communities of Cody, Byron, Lovell, Powell, Frannie, Deaver, and rural areas through the year 2030. Therefore, the total required pipeline capacity is approximately 87 mgd. A 48-inch diameter pipeline is required to convey the combined flow from the trifurcation structure to the Sulphur Creek crossing. At that point the municipal water supply would be diverted through a separate pipeline to Cody and a 36-inch pipeline would convey irrigation water across Sulphur Creek to the Cody Canal.

In addition to the diversion and pipeline conveyance system, check structures or other improvements will be required in the Cody Canal to ensure that water depth will be high enough to supply existing laterals. This is because flow in the Cody Canal may be reduced by 100 cfs from the point of diversion on the South Fork to where the exchange water supply enters the Cody Canal near Sulphur Creek.

The maximum diversion right of the Cody Irrigation District is approximately 360 cfs at 2 cfs per 70 acres irrigated. If only 1 cfs per 70 acres is available during a drought condition, 180 cfs would be diverted. As previously indicated, up to 100 cfs may flow into Buffalo Bill Reservoir instead of entering the Cody Canal system as a result of the exchange agreement. Therefore the range of potential flow in the upstream 15 miles of the Cody Canal system may be 80-260 cfs before the 100 cfs is reintroduced into the canal at Sulphur Creek. During the beginning and end periods of the irrigation season the minimum flow may even be less than 80 cfs due to the tapering off of irrigation requirement. For the purposes of this study a minimum flow of 50 cfs is assumed with a range of 50-260 cfs in the upper reach between the headgate and Sulphur Creek con nection point. There are 36 laterals, 13 check and drop structures, 3 overflow structures, and 4 major stream crossings along the reach in question. The loca tions of these appurtenances are also shown on Figure 6. Many of the existing check and overflow structures are quite old and are in very poor condition. Based upon an analysis of water surface elevations during reduced flow con ditions, it is apparent four new check structures will be needed to accommodate the estimated low flow conditions, and 11 existing check structures replaced as a result of their deteriorated condition. If new check structures are installed and existing checks upgraded, it is recommended that gated checks be provided in stead of stop logs. A typical gate type check structure is shown in Figure 7.

COST ANALYSIS

A cost analysis is necessary to determine whether expenditures for improve ments due to the exchange agreement will be offset by increased crop production value (or reduction of potential losses in water short years) as a result of greater water supply. If that is not the case, it would not appear to be prudent to further pursue the exchange agreement. A comparison of the two can be made and benefit to cost ratio established. Costs to upgrade the efficiency of the current Lakeview system (thereby conserving water) as an alternative to obtain ing additional water through an exchange agreement are also discussed.

CROP VALUE ANALYSIS

The value of all crops for the LID are directly dependent on the availability of water supply. In water short years, crop production levels and overall crop

II-8 I

o / 1 I LEGEND scale mile -+16 TURNOUT o ABANDONED TURNOUT o CHECK STRUCTURE • DROP STRUCTURE 'BUFFALO )( BRIDGE 6 WASTEWAY • PUMPHOSE INLET [CD SURVEYED CROSS SECTION BILL

.0 ... ')& <0 --I

CODY CANAL FACILITIES FIGURE 6 ------~------

I I • I I •o o I I 1 1 I I 10 'lit - rLJ, ;....+--- 1---

ALUMINUM SLIDE GATE •o AND OPERATOR 1 (TYP. OF 4) , t t 10 ------t----...,--......

PLAN

OPENING (TYP.)

C/) w a: CONCRETE CUTOFF WALL . .coo.. 1> 'N .... 20'-0· ELEVATION

TYPICAL GA TE-TYPE CHECK STRUCTURE FIGURE 7 values are lower due to lack of sufficient water which stresses a crop resulting in a lower yield per acre. The method of determining the value of LID crops follows:

(1) A dollar value was placed on each type of crop grown per acre. This value was determined from recent selling prices and discussion with local farmers.

(2) Maximum realistic yield per acre for various crop types were also established per discussion with local farmers.

(3) Water supply shortages due to legal limitations and hydrologic con ditions were estimated.

(4) Crop yield reduction factors were calculated based on estimated de pressed evapotranspiration and crop production function values.

(5) Potential, reduced, and lost value of production estimates were cal culated and compared for combinations of crops under the range of water supply conditions previously established.

As discussed previously, the LID has an apparent maximum legal entitlement to 267.0 cfs and the estimated range of supply shortage during critical crop growth periods varies from approximately 0-50 cfs in average years to approximately 95 cfs two years out of ten.

The effect of water supply shortages was evaluated in regard to crop yields on a biweekly basis for a combination of crop patterns and range of water supply conditions. Eight different crop patterns were evaluated over a range of prob ability of supply of 50 percent to 100 percent of historical availability. The results of the crop yield analysis is presented in Table 5. The total value of potential crop production at the various water supply probability levels is shown on the chart at the left, and the estimated annual losses of crop income due to insufficient water is shown at the right. Data summaries are highlighted in the boxed areas.

The set of data shown at the right side of Table 5 actually represents differences between maximum yield and expected yield. However, it is unlikely that maxi mum yield could ever be attained. As a result, the difference between the values in the block labeled "AVERAGE LOSS, ALL YEARS, ALL CROPS" and the values labeled "LOSS AT 50% EXCEEDENCE SUPPLY," is a more reasonable estimate of average annual production not realized due to LID water supply shortages. This data is presented in Table 6. Crop combinations 1, 2 and 6 represent the most likely combinations to be grown on the Lakeview system due to climate and risk.

EXCHANGE IMPROVEMENT COSTS

Capital Costs

Improvements necessary as a result of the exchange agreement consist of im provements to the Cody Canal, new conveyance facilities necessary to deliver water from Buffalo Bill Reservoir to the Cody Canal and level contr'ol structures

II-9 'l'ABT,E 5

VALUE (W LAKEVIEW I HRIGATION DISTRICr PRODUC'I'ION ANlJ UNREALrZED POTENTIAL PRODUCTION

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IU JlUI. 111.611 /H.W lUll US,OIfI.J1S.0S0 m.m 11I.S •• ,1.S) J. 6/f 10. 10.' AHIAU 'IO.OCJ/". AU rlUS Af{IH[ lOSS. All flUS. ALL Clors 1.S1t. JI1 III 10.' S1U.t1J lUI 10.1 l.lIl.m In '0.1 JSUU III 10.2 I l.l6t.1U m 10.1 m.w m IO.J . 1.m.0I2 III 10 .• IOJ.fIl 11110 .• 11. &II. III III '0. 5 )f) • lIS III 10.5 I , /.HU.S III 10.6 I1I00.'s) 10110.' 1. m . IJ1 lUI Id. I S14/011 101 10.1 L~lt·) ce; ~:~~~.! __ ._ fl~O IJ~ ru ••~ I TABLE 6

THE VALUE OF INCREASED PRODUCTION ON THE LAKEVIEW mRIGATION DISTRICT WITH AN ENHANCED WATER SUPPLY!

Value of Crop Average Loss Loss of Increased Annual Combination All Years 50% Exceedance Production (Run No.) All CropsZ Water SupplyZ (1) - (Z) = (3)

1 Z 3

*1. $ 366,937 $ 149,732 $ 217,241

*2. 354,386 77,101 277,376

3. 296,924 48,716 248,208

4. 301,432 27,420 274,012

5. 343,215 28,359 314,856

*6. 300,153 69,366 230,787

7. 341,021 49,983 291,038

8. 459,877 65,029 394,848

1. These values represent reasonably attainable levels of increased production given at least a 50% exceedance water supply.

2. These values are from the second set in Table 6-1.

* Crop combinations 1, 2, and 6 are the most likely combinations to be grown on the Lakeview system due to climate and risk. Combination 1 was the actual crop distribution grown in 1983.

II-II for six diversions along the South Fork of the Shoshone River. Cody Canal improvements consist of four new check structures and upgrade of eleven exist ing check structures. Conveyance facilities include construction of approxi mately 11,200 feet of 48 and 36 inch diameter pipeline, metering facilities, energy dissipation structure, valves, and associated pipeline appurtenances. The level control structures consist of six 1.5 foot high approximate 100 foot long concrete walls with rip-rap protection. The proposed exchange agreement indi cates that the Lakeview Irrigation District will pay for all irrigation related improvements required to facilitate the agreement. A breakdown of exchange improvement costs is shown in Table 7.

The Lakeview share of item 1 is based on paying for all new check structures required due to low flow conditions in a portion of the Cody canal, and for upgrading existing check structures. The Lakeview share of Items 2, 4, and 5 is based on the proportionate share of the total cost if the Shoshone municipal supply project and exchange project were to be constructed individually. In other words, costs were calculated for these items for each project if con structed individually, and each cost divided by the total of the two. The propor tionate share was 2/3 to Lakeview and 1/3 to the Shoshone project. That method appeared to be the most equitable as opposed to a equal split or capacity based split. Items 3, 6, and 7 are totally allocated to Lakeview as they are not related to the municipal water supply project. The Lakeview share of the total project costs would be $3,512,000.

Operation and Maintenance Costs

In addition to capital costs, there are operation and maintenance costs as sociated with new improvements. For the purposes of this study it is assumed all new improvements will be manually operated in lieu of automated remote con trol systems. There would be very little operation and maintenance expense associated with new facilities. One person should be able to operate and main tain all new facilities. Very little additional maintenance would be required for the new facilities. For the purposes of this study it is assumed one person would be utilized for O&M during the irrigation season at an annual cost of $10,000. It is also asstimed a maintenance and equipment replacement fund of $5,000 per year would be provided. Thus, total 0& M costs would be about $15,000 per year.

Benefit to Cost Ratio

Benefit to cost ratio is used in many cases to determine economic viability of a project. In general, a ratio greater than one indicates economic feasibility, although higher ratios are sometimes desired to decide where investment funds can be used to best advantage. To arrive at the benefit to cost ratio, annual or total present worth costs must be compared. In this analysis, an annual cost comparison will be made as most economic data has been previously calculated in that manner. Table 8 presents the total exchange improvement costs amor tized for 50 years for interest rates varying from 4 to 8 percent. Since the state may fund a large portion of the capital cost (up to 75 percent), two levels of Lakeview's participation in total annual costs are also shown depending on level of state funding.

The annual crop value benefits are shown in the third column of Table 6 with the most likley crop combinations to be grown are indicated as numbers 1, 2, and 6.

II-12 TABLE 7

EXCHANGE IMPROVEMENT COSTS*

Total Anticipated Lakeview Item No. Descri~tioD Cost Share of Cost

(1) Cody Canal check structures (15) $ 413,000 $ 413,000

(2) 10,100 feet.:!: of 48 inch diameter 1,548,000 1,037,000 pipeline

(3) Sulphur Creek Canyon crossing 270,000 270,000 (1100 feet.:!: 36-inch diameter)

(4) Connection to trifurcation structure 61,000 41,000 and metering facilities

(5) Valves and appurtenances 105,000 70,000

(6) Energy dissipation structure and 37,000 37,000 canal inlet

(7) Shoshone River level control 120,000 120,000 structures (6)

Subtotal Construction Costs $2,554,000 $ 1,988,000

Contractor mob./demob., OH&P and bonds @ 25% 639,000 497,000

Subtotal $3,193,000 $ Z,485,000

Contingencies @ 15% 479,000 373,000

Total estimated construction cost 3,672,000 2,858,000

ROW acquisition (6,000 feet .:!:) 12,000 8,000

Engineering @ 16.6% 610,000 474,000

Legal and Admin. @ 3% 110,000 86,000

Cost of financing @ 3% 110,000 86,000

Total Estimated Project Cost $4,514,000 $ 3,51Z,000

*Cost estimates indicated herein have been performed to a range of accuracy of +30% to -15% in conformance to level of accuracy expected for a predesign report by the American Association of Cost Engineers.

II-I3 Combination number one is the current pattern. The annual crop value increased value for those combinations as a result of increased water supply are as follows:

Crop Com bina tion Annual Increased Value

No. 1 217,241 No.2 277,376 No.6 230,787

TABLE 8

EXCHANGE IMPROVEMENTS ANNUALIZED COST

Interest Rate Financed 4% 6% 8%

Lakeview Project Cost ($3,512,000)

Annual Cost - 50 years 163,000 223,000 287,000 Annual 0& M Cost 15,000 15,000 15,000 Total Annual Cost 178,000 238,000 302,000

Benefit-to-Cost Ratios ($3,512,000 Costs) Benefit/Cost Ratios @ Various Interest Rates Crop Combination 4% 6% 8%

No.1 1.22 0.91 0.72 No.2 1.56 1.16 0.92 No. 3 1.30 0.97 0.76

Lakeview Funded Portion (per year)

25% of Capital Costs & O&M 56,000 71,000 87,000 50% of Capital Costs & O&M 97,000 127,000 159,000

As can be seen from Table 8, if the project could be financed at 4% interest rate, the benefit to cost for the project would be favorable, whereas at 8% it would not. Discussion of financing alternatives with one financial lending insti tution indicated that the project could probably be financed at an interest rate of 5.5 to 6 percent. At that rate the benefit to cost would be approximately a "push" for crop combinations 1 and 6 and favorable for combination number 2. From the LID perspective the project would be favorable even if funded by the state at the 50% level.

The above favorable benefit to cost ratios are based on a number of assumptions which could significantly alter the indicated results if the assumptions are false. There assumptions are as follows:

IT-14 • Both the Shoshone municipal supply project and irrigation project would proceed together. If the irrigation project had to proceed alone and pay all costs, the project would not appear to be favorable except at a low interest rate of 4%.

• The sharing of costs between the two projects would be as indicated.

• Financing would be available at a maximum 6 percent interest rate over a 50 year period.

LAKEVIEW mRIGATION DISTRICT UPGRADE COSTS

A potential alternative to obtaining additional water through an exchange agree ment would be to u,pgrade the efficiency of the existing LID conveyance and field application systems. While it is beyond the scope of this report to provide a detailed investigation of needed improvements and cost, preliminary costs can be estimated to indicate whether that alternative should be evaluated in more de tail. It may be more economical to upgrade the existing system and conserve water rather than import additional water.

As previously indicated, the Soil Conservation Service (SCS) evaluated the Lake view Canal system in 1983 and recommended a significant list of improvements totaling $1,062,000 (1983 dollars), to be made over a 40 year period. Most of the improvements are related to replacing existing structures and maintaining the present system rather than specifically increasing the efficiency of the canal system (although some efficiency increase would result). In addition, there were some specific areas pointed out in the report where system efficiency could be improved.

It was suggested that approximately 3500 acres in the Irma Flats areas could be converted to sprinkler irrigation increasing field application efficiency by 20 percent with an average annual savings of 3560 acre-feet (10 cfs average flow). The SCS construction cost estimate (1983) to install the pipelines and sprinkler system was $1,182,000. Adding 50 percent for contingency, engineering, financ ing, legal, and inflation, the 1985 cost would be $1,773,000. Thus, the cost per acre foot to convert some acreage to sprinkler application would be $500 per acre foot versus $350 per acre foot for exchange agreement water.

Another potential area for significant water conservation would be to control seepage in the canal which is estimated at 100 cfs at full flow conditions (270 cfs 2:) in the SCS report. One canal reach of approximately 4.2 miles has been estimated to lose approximately 16 percent of flow. At an average annual Lake view flow of 137 cfs that would amount to approximately 7800 acre feet annually (22 cfs average flow). An approximate cost to line the canal and prevent seep age would be $70 per foot for PVC lining overlaid by 10-inches of native fine soil and 8-inch pitrun gravel. Estimated service life would be 30-50 years. Thus, the construction cost would be $1,552,000 for a 4.2 mile reach. Adding for contingency, engineering, etc., total project cost (1985) would be $2,142,000. The cost per acre foot would be approximately $275 per acre foot.

Preliminary estimates of increasing system efficiency through sprinkler applica tion or canal lining in those areas mentioned above, would appear to indicate that conversion to sprinkler application systems would be more expensive than exchange water, however, canal lining of high loss areas may be a cost effective alternative.

II-IS

SHOSHONE MUNICIPAL SUPPLY PROJECT SHOSHONE MUNICIPAL SUPPLY PROJECT

INTRODUCTION

This summary of the Shoshone Municipal Supply Project is divided into four main areas of the project: 1) water supply alternatives during maintenance of the Shoshone Conduit; 2) Buffalo Bill Reservoir diversion/conveyance alternative; 3) water treatment; and 4) water transmission.

WATER SUPPLY ALTERNATIVES DURING SHOSHONE CONDUIT SHUTDOWN

An alternate method of delivery for Buffalo Bill Reservoir (BBR) water, or an alternate source of water, is required for periods when the Shoshone Conduit is shut down for maintenance and minor repairs.

The following discussion summarizes the results and recommendations of the initial analyses, the analytical disciplines employed for the detailed evaluation described herein, and the revised Shoshone Municipal Supply Project water demands.

WINTER SUPPLY OPTIONS

Two basic alternatives were developed during the Level I BBR Diversion Alterna tives Analysis for supplying water to the Shoshone Project during periods when the Conduit is not in use. The two options were downstream storage of the water and pumping water from the Shoshone River. Downstream storage presently exists in the form of Beck Lake, and Markham and New Cody Reservoirs. The proposed winter use pump station would be located on the Shoshone River near DeMaris Hot Springs.

WATER DEMANDS

The estimated 2030 water demands for the Shoshone Water Supply Project were revised following the completion of the Level I Analysis of the BBR Diversion, the Update of the Shoshone Supply Reconnaissance-Level Report, and the Big Horn Basin Groundwater Supply Project. The revisions reflected public comment on the contents of the above reports and the results of drilling programs undertaken by the "Groundwater Communities." A summary of the revised estimated water demands for the Shoshone Municipal Supply Project is presented in Table 1.

TABLE 1

SHOSHONE MUNICIPAL SUPPLY PROJECT ESTIMATED WATER DEMANDS

Average Daily Peak Daily Flow Flow Year (mgd) (mgd)

1990 3.6 8.8 2000 4.3 12.2 2010 5.1 15.5 2020 5.7 18.7 2030 6.5 22.0

ill-I A representation of the seasonal demand variation is presented in ·Figure 1. This analysis provided the following information:

o The average domestic demand for the period of November through March is approximately 77 percent of the average yearly demand. Historically, the Shoshone Conduit has been shut down sometime during this period of time for maintenance and/or repair work. The duration of the shutdowns have varied with the complexity of the repair work.

o For the records of the years analyzed (1979 through 1984), the highest winter demand for a one-month period occurred in January 1984. The average domestic demand for this month was about 94 percent of the average yearly demand.

o For the five months of the year when a shutdown of the Conduit can be expected, water usage is highest in January. The average demand in January is approximately 82 percent of the average yearly use.

STORAGE REQUIREMENTS

The earlier work on this project established the criteria for an alternate source of supply or method of delivery if the Shoshone Conduit were to be used as the primary means of delivery for BBR water. A conservative estimate of a 12-week shutdown period was originally used to estimate the maximum amount of downstream storage that would be needed for such periods. This assumption was to be confirmed during the Level IT analyses.

A 35-year period of Bureau of Reclamation records was analyzed for frequency and duration of the shutdown periods. The evaluation revealed that a shutdown of 12- weeks duration has a relatively high frequency of occurrence; approximately 91 percent of the time, the Conduit shutdown period will be 12 weeks or less.

Because of its relatively high frequency of occurrence, a 12-week shut down period was also used in this Level IT analysis to estimate winter storage needs. Ideally, the reliability of the supply would be much higher than 91 percent; more on the order of 98 or 99 percent. However, sufficient data did not exist to satisfactorily project the estimate of shutdown duration to the 99 percentile level. It is anticipated that the length of maintenance shutdowns will decrease with the implementation of the improvements to Buffalo Bill Dam. Only additional operational experience will indicate whether a 12-week storage period is sufficiently conservative. An average winter demand of 80 percent of average yearly demand was used to calculate the necessary net storage volumes. However, a storage efficiency of 90 percent was also used to estimate gross storage requirements. The resulting winter demands and storage volumes for the project planning period are presented in Table 2.

m-z 1.5

o 1.0 ------i= « 0: C Z RATIO OF AVERAGE « MONTHL Y DEMAND TO ~ w AVERAGE YEARLY DEMAND c 0.5

o~--~--~--~--~--~~--~--~--~--~----~--~--~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

MONTH

SEASONAL FLUCTUATION IN DOMESTIC WATER DEMAND FOR THE CITY OF .CODY FIGURE 1 TABLE Z

SHOSHONE MUNICIPAL SUPPLY WINTER WATER STORAGE REQUIREMENTS

Average Winter Net Storage Gross Storage Daily Demand Year (mgd) (MG) (Ae-ft) (MG) (Ae-ft)

1990 2.9 244 768 272 853 2000 3.5 291 913 323 1014 2010 4.0 339 1063 376 1181 2020 4.6 384 1206 427 1340 2030 5.2 433 1361 482 1513

BUFFALO BaL RESERVOm DIVERSION/CONVEYANCE ALTERNATIVES

In addition to providing for the project supply requirements during periods of conduit shutdown, the other principal supply component is of course, the raw water conveyance facility. Three conveyance alternatives were evaluated for either a combined Shoshone/Lakeview Project, or for an independent Shoshone Supply Pro ject. The diversion/conveyance alternatives are:

• Shoshone Municipal Supply only.

• Combined Shoshone/Lakeview Projects supply with the use of the Cody Canal for potable water supply.

• Combined Shoshone/Lakeview Projects supply without the use of the Cody Canal for potable water supply.

The first alternative was developed to determine the characteristics of the Shoshone Municipal Supply Project should the Lakeview Exchange Project not prove viable. The last option was developed to assess the incremental costs associated with the avoidance of the water quality degradation that takes place in the Cody Canal. In all three cases, the basic components are the same: diversion of BBR water from the Shoshone Conduit Trifurcation Structure and conveyance to a new water treatment plant to be located near the existing City of Cody plant.

OPTION 1 - SHOSHONE MUNICIPAL SUPPLY ONLY

Should the Lakeview Exhcange Project not prove viable, then water would be supplied to the Shoshone Municipal Project in a pipeline sized for the peak day demand for the planning period; 22.0 mgd. As shown on Figure No.3, a 30-inch diameter pipeline would satisfactorily convey this flow to the plant.

OPTION Z - COMBINED DIVERSION WITH THE LAKEVIEW EXCHANGE; CODY CANAL UTlldZED FOR POTABLE WATER SUPPLY

This alternative is essentially the approach recommended in the BBR Diversion alternatives report. During the irrigation season the combined flows of the

m-3 ~ 0- 34

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BBR DIVERSION OPTION 1 FIGURE 3 Lakeview Exchange Project (100 cfs max.) and the Shoshone Municipal Supply would be diverted from the Trifurcation Structure and carried in a common conveyance to the Cody Canal. Water would be withdrawn from the canal for treatment and distribution to the Shoshone Municipal Supply.

During the periods when the Cody Canal is not in use, water would be transmitted to the treatment plant in a smaller pipeline which branches off from the combined conveyance on the west bank of Sulphur Creek Canyon (see Figure 4). The com bined flow pipeline would be 48-inches in diameter, while the smaller branch line would be an 18-inch diameter pipeline.

OPTION 3 - COMBINED DIVERSION WITH THE LAKEVIEW EXCHANGE; CODY CANAL NOT UTll.JZED FOR POTABLE WATER SUPPY

WINTER PUMPING STATION AND TRANSMISSION LINE

The winter pumping station alternative was analyzed in three forms to match the three options for the BBR diversion. For all cases, the basic components of the pumping station and winter use transmission line were the same. The pump station would be located on the east bank of the Shoshone River near the DeMaris Springs crossing. A 16-inch diameter transmission line would connect the pump station to the Shoshone Municipal Supply main at a point just west of Sulphur Creek. A schematic of this system is presented in Figure 6.

Several options for the river intake were analyzed for potential application. Pend ing a more complete design level analysis of the river bottom materials, an infiltration gallery was selected for the intake. The infiltration gallery would consist of a specially prepared area in the middle of the river. Perforated pipe or well screen, placed well below the river bottom would collect the water and transmit it to the pumping station located on the nearby bank. The gallery would have an effective collection area of about 3600 sf. A schematic of the gallery and pump station is presented in Figure 7. The pump station would consist of an intake wet well located below river grade, and an equipment level above the floodplain elevation.

DOWNSTREAM WINTER STORAGE

As described previously, the existing reservoirs, with the exception of Alkali Lake, are used by the City of Cody to provide a source of water for winter operation of its

ID-4 ...... ~.

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BBR DIVERSION OPTION 2 FIGURE 4 • "~~"~A , ; to> • "j '\.0 \ i cr· t,J ~ o '\ (8M 5002) " ~ "',\. • • _a • 34 ,~~~~?~~~~~~·32 , - - --

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':c, , '~~'" r---' / v' ;'1, ': ,,' LOT 48 or '\'>" .. ,' , ' Mm~ " 15-,,/ \, BBR DIVERSION OPTION 3 FIGURE 5 WINTER SUPPLY PUMPING STATION AND TRANSMISSION LI NE FIGURE 6 sz SHOSHONE RIVER 16-0 INTAKE LINES COARSE RIVERBED NEW WINTER SUPPLY MATERIAL ------~~ PUMPING STATION PEAGRAVEL-----1iIl~c:======~~~~~~f~=-=-~~-1' INFIL TRA TION --- TRANSMISSION MAIN COARSE BEDDING GALLERY MATERIAL 16-£1 PERF. PIPE OR GEOTEXTILE FILTER FABRIC WELL SCREEN LATERAL (TYP. OF 3) -~------~

TYPICAL SECTION - INFIL TRA TION GALLERY

SITE PLAN

25'±

OVERHEAD GANTRY CRANE PUMP (TYP. OF 3) PUMP (TYP. OF 3)

- FLOOR ELEV. seT ABOVE .... I DESIGN FLOOD STAGE I 10 SURGE TANK --t--~ I .f.1 .... I ' J,~ ELECTRICAL EQUIPMENT 20·0' INTAKE FROM GALLERY DIESEL V '9 V GENERATOR --+-~ PUMPING WET WELL

PLAN SECTION

WINTER PUMPING STATION SCHEMATIC FIGURE 7 treatment plant. The City of Cody has filed the necessary water rights applications and started field work on the enlargement of this system. The enlargement consists of raising the Beck Lake dam, connecting Beck and Alkali Lakes, installing a new inlet into the reservoirs and dredging each of the impoundments to remove sedi ment and organic material accumulations, and restore original capacities. The proposed storage system is presented in Figure 8. Between the maximum and minimum levels the combined volumes of Beck and Alkali Lakes is approximately 1260 ac-ft. The usable storage in Markham and New Cody Reservoirs is 67 and 508 ac-ft, respectively. Therefore, a total working volume of 1835 ac-ft would be made available for winter storage, an amount which is well in excess of the 1513 ac-ft required for a 12-week period in the year 2030.

The main components of this project are:

• Raising the Beck Lake impoundment dam by three feet.

• Dredging and clean-up of Alkali Lake (approximately 175,000 cy).

• Potential seepage control project for the adjacent portion of Cody Canal. Approximately 7500 If of canal could require a lining to prevent seepage and limit the migration of dissolved solids into the lake. It is recommended that such action be deferred until after the storage system is put into use and monitored for a period of time.

• Potential interceptor ditch and/or seepage trench constructed south of Alkali Lake. As with the previous item, such a system may not prove necessary.

• Construct a new diversion and turnout on Cody Canal to provide water to the combined Alkali/Beck Lakes.

• Construct an isolation/overflow structure for the unused portion of Alkali Lake east of Highway 120.

• Construct a connecting pipeline with control structure between Alkali and Beck Lakes.

• Construct an intake and pumping station of 5.2 mgd capacity for lifting water from Beck Lake to the smaller reservoirs at the new water treatment plant.

HYDROGEOLOGY/WATER QUALITY

The greatest concern over the use of Alkali Lake is the extremely high mineral content of the water. The exact source of the water supply for the lake was uncertain, but was surmised to be a combination of surface runoff, canal seepage and irrigation return flows. However, because of the abundance of mineral springs in the area, a mineralized seep could not be immediately eliminated from con sideration.

A hydrogeolic analysis of the area was conducted to evaluate the potential for the existance of mineral springs in the Alkali/Beck Lakes area. The investigation consisted of a site investigation and literature research on the area geology. The

m-5 RAISE AND IMPROVE BECK LAKE DAy

OF ALKALI LAKE ,>;:'<;~; ~ - '\ --____ '""""'=..J.... /' ---- .,..,/ . POTENTIAL INTERCE-:::R / \ , DITCH OR TRENCH \ ~

REACH OF CANAL TO BE POTENTIALLY LINED

t TO MEETEETSEE

CONSTRUCT NEW CHECK AND TURNOUT

WINTER STORAGE SYSTEM FIGURE 8 investigation revealed that the lakes are underlain by several thousand feet of predominantly shale beds, which dip northwest to southeast (as contrasted with the slope of the topography in the immediate area). Upward migration of water through this type of barrier is very unlikely. Furthermore, no apparent opportunity for recharge exists.

Therefore, the previously described combination of irrigation return flows, canal seepage and surface runoff is the source of Alkali Lake. The limited depth of the lake, together with the high summer evaporation potential and the poor quality of the influent flows, appears to be responsible for its very poor quality. Conse quently, combining Beck and Alkali Lakes is judged to be a viable alternative for downstream storage for the Shoshone Municipal Supply. The biggest problem in implementing this alternative would be the disposal of the existing high TDS (total dissolved solids) lake water and the associated mineralized lake bottom sediments.

FUTURE OPERATIONS

With the implementation of a regional water treatment plant at this location, the pattern of use of Beck Lake could change significantly. Assuming that Beck Lake is combined with Alkali Lake and that this combined impoundment is used as a source of supply for the Shoshone Municipal Supply WTP during periods when the Conduit is shutdown, certain operational criteria would have to be adhered to, to ensure that the reservoirs remained viable as potable water sources. Most critically, Beck/ Alkali Lakes must continue to be flushed during the summer irrigation season. Should the irrigation district change its mode of operation and discontinue its use of the reservoirs, then mineral levels would quickly rise to unacceptable levels.

A gradual, long term increase in average mineral content in the impoundment may also occur. Assuming that the irrigation flow into the combined reservoirs does not incI:ease from the present levels, the benefits derived from this flushing action would be expected to diminish in the larger volume of the combined impoundments. Therefore, it may become necessary to reduce the amo~t of seepage and/or surface runoff that enters these lakes. Although not recommended for immediate implementation, such measures would include lining a reach of the Cody Canal with an impermeable membrane and/or constructing an interceptor ditch or seepage trench along the south side of the reservoirs.

PROJECT COST ESTIMATES

The cost estimates provided below have been inflated to the estimated midpoint of construction, May 1988. The corresponding Denver ENR is estimated to be 3700. The costs include the contractor's overhead and profit (15 percent), contingencies (15 percent), engineering (16.5 percent), and legal and administrative costs (3 percent). The accuracy of these costs is in the range of minus 20 to plus 30 percent of actual costs, as determined with a very preliminary level of engineering detail, or a "budget estimate" as defined by the American Association of Cost Engineers.

BUFFALO Bll.L RESERVOm. DIVERSION

Option 1 - Shoshone Municipal Supply Only

Should the Lakeview Exchange Project not prove to be viable, a conveyance for only Shoshone Municipal Supply water would be constructed from the Trifurcation

m-6 Structure to the proposed Municipal Supply WTP. Estimated project development costs are presented in Table 3~

Option Z - Combined Diversion; Cody Canal Utilized for Potable Water Supply

As recommended in the original BBR Diversion Report, a single conveyance would be used during the irrigation season to carry the combined flow to Cody Canal. The Shoshone Municipal Supply would be withdrawn from the Cody Canal at the WTP site. A separate branch line would be used to convey the Shoshone Supply to the WTP from the large transmission main during the non-irrigation season. Table 4 presents the project cost estimate for this alternative.

Option 3 - Combined Diversion; Cody Canal not Utilized for Potable Water Supply

Although both flows would be diverted from the Trifurcation Structure, a separate transmission line would be used to carry the Shoshone Supply from the large transmission line to the WTP at all times of the year. Table 5 presents the project cost estimate for this alternative.

WINTER PUMPING STATION AND TRANSMISSION LINE

An alternate consisting of a pumping station, located on the Shoshone River near DeMaris Springs, was developed as a supply option for the periods when the Shoshone Conduit is out of service. The pump station would be connected to the Shoshone Supply portion of the BBR Diversion at a point just west of Sulphur Creek. The pump station would deliver flow to the WTP at the average daily demand for the normal period of shutdown; any time from November through March. Peak monthly demands would be met by utilizing Markham and/or New Cody Reservoirs for short term raw water storage. Water would be delivered to these reservoirs in late autumn, prior to the Conduit shutdown. The estimated project cost for this alternative is presented in Table 6.

DOWNSTREAM WINTER STORAGE

The other alternative for water supply during the periods when the Shoshone Conduit is out of service consists of downstream storage. Beck and Alkali Lakes would be combined to provide sufficient storage to supply the average winter day demand for a period of 12 weeks. A pump station would be used to lift the water from the combined impoundments to the upper reservoirs (Markham and New Cody) or the new WTP. The pump station would deliver the average daily demand for the period from November through March. The estimated cost for this alternative is presented in Table 7. Note that this estimate is somewhat optimistic in nature, in that th epotential costs for preventing the intrusion of seepage into the storage reservoirs have not been included.

SUMMARY AND RECOMMENDATIONS

BBR DIVERSION

If the Lakeview Exchange does not materialize, the Shoshone Municipal Supply will be served by a 30-inch diameter transmission line from the Trifurcation Structure. The total estimated project cost for this system is approximately $4.1 million (at assumed mid-point of construction in 1988).

m-7 TABLE 3

OPTION 1 - BBR DIVERSION PROJECT DEVELOPMENT COST ESTIMATE

Item Quantity Estimated Cost

I. 30-inch diameter pipeline 28,300 If $ 2,117,000 2. Trifurcation Structure modifications Is 16,000 3. Sulphur Creek Crossing Is 51,000 4. Control telemetry Is 50,000 5. AC pavement replacement 3,600 sy 76,000 6. Valves, blow-offs, & AV / ARV assemblies Is 33,000 7. Other pipeline appurtenances Is 77,000

Construction Subtotal $ 2,420,000 8. General construction expenses (mobilization, bonds, etc.) (5%) 121,000

Subtotal $ 2,541,000

9. Contractor's overhead & profit (5%) 381,000

Subtotal $ 2,922,000

10. ROW acquisition 17,000 If 34,000

Subtotal $ 2,956,000

II. Contingencies (15%) 444,000

Total Estimated Construction Cost $ 3,400,000

12. Engineering (16.5%) 561,000 13. Legal & administrative (3.0%) 102,000

TOTAL ESTIMATED PROJECT COST $ 4,063,000

ill-8 TABLE 4

OPTION 2 - BBR DIVERSION PROJECT DEVELOPMENT COST ESTIMATE

Item Quantity Estimated Cost

I. Com bined diversion conveyance 50% of cost $ 1,010,000 2. 18-in diameter pipeline 18,070 If 750,000 3. Sulphur Creek crossing Is 53,000 4. Control Telemetry Is 50,000 5. AC pavement replacement 3,600 sy 76,000 6. Valves, blow-offs, & AVIARV assemblies Is 21,000 7. Other pipeline appurtenances Is 28,000

Construction Subtotal $ 1,988,000

8. General construction expenses (mobilization, bonds, etc.) (5%) 99,000

Subtotal $ 2,087,000

9. Contractor's overhead & project (15%) 313,000

Subtotal $ 2,400,000

10. ROW acquisition 17,000 If 34,000

Subtotal $ 2,434,000

II. Contingencies (15%) 366,000

Total Estimated Construction Cost $ 2,800,000

12. Engineering (16.5%) 462,000 13. Legal & Administrative (3.0%) 84,000

TOTAL ESTIMATED PROJECT COST $ 3,346,000

m-9 TABLE 5

OPTION 3 - BBR DIVERSION PROJECT DEVELOPMENT COST ESTIMATE

Item Quantity Estimated Cost

I. Com bined diversion conveyance 50% $ 875,000 (shared portion only) 2. 36-in diameter pipeline 7,000 If 617,000 3. 30-in diameter pipeline 11,070 If 790,000 4. Suiphur Creek crossing Is 53,000 5. Control telemetry Is 50,000 6. AC pavement replacement 3,600 sy 76,000 7. Valves, blow-offs, & AVIARVassemblies Is 33,000 8. Other pipeline appurtenances Is 56,000

Construction Subtotal $ 2,550,000

9. General construction expenses (mobilization, bonds, etc.) (5%) 128,000

Subtotal $ 2,678,000

10. Contractor's overhead & project (15%) 402,000

Subtotal $ 3,080,000

II. ROW acquisition 17,000 If 34,000

Subtotal $ 3,114,000

12. Contingencies (15%) 467,000

Total Estimated Construction Cost $ 3,581,000

13. Engineering (16.5%) 591,000 14. Legal & Administrative (3.0%) 107,000

TOTAL ESTIMATED PROJECT COST $ 4,279,000

m-l0 TABLE 6

WINTER PUMPING STATION & TRANSMISSION LINE PROJECT DEVELOPMENT COST ESTIMATE

Item Quantity Estimated Cost

I. 16-in diameter pipeline 7,150 If $ 276,000 2. 30-in diameter bored highway crossing 100 If 33,000 3. AC pavement replacement 5,500 sy 116,000 4. Valves, blow-.offs, & AV/ARV assemblies Is 13,000 5. Other pipeline appurtenances Is 10,000 6. River intake Is 570,000 7. Pump station structure Is 312,000 8. Pump station mechanical equipment Is 295,000 9. Pump station electrical equipment Is 265,000 10. Pump station sitework Is 50,000

Construction Subtotal $ 1,931,000

II. General construction expenses (mobilization, bonds, etc.) (5%) 96,000

Subtotal $ 2,027,000

12. Contractor's overhead & project (15%) 304,000

Subtotal $ 2,331,000

13. ROWand land acquisition Is 15,000

Subtotal $ 2,346,000

14. Contingencies (15%) 352,000

Total Estimated Construction Cost $ 2,968,000

15. Engineering (16.5%) 445,000 16. Legal & Administrative (3.0%) 81,000

TOTAL ESTIMATED PROJECT COST $ 3,ZZ4,OOO

m-ll TABLE 7

DOWNSTREAM WINTER STORAGE PROJECT DEVELOPMENT COST ESTIMATE

Item Quantity Estimated Cost

I. Raise Beck Lake dam Is $ 14B,000 2. Drege & clean Alkali Lake 175,000 cy 1,333,000 3. Turnout check structure Is 20,000 4. Turnout & flow measurement structures Is 32,000 5. 4B-in diameter pipeline 4,500 If 450,000 6. Energy dissipation structure Is 15,000 7. Isolation/overflow structure Is 3,000 B. Beck/ Alkali Lakes intertie control structure Is 12,000 9. 72-in diameter pipeline 2,100 If 474,000 10. Lake intake Is 13B,000 II. 16-inch diameter pipeline and appurtenances 1,100 If 39,000 12. Pump station structure Is 69,000 13. Pump station mechanical equipment Is 210,000 14. Pump station electrical equipment Is 200,000 15. Pump station sitework Is 25,000

Construction Subtotal $ 3,168,000

16. General construction expenses (mobilization, bonds, etc.) (5%) 15B,000

Subtotal $ 3,326,000

17. Contractor's overhead & project (15%) 499,000

Subtotal $ 3,B25,000

lB. Contingencies (15%) 574,000

Total Estimated Construction Cost $ 4,399,000

19. Engineering (16.5%) 726,000 20. Legal & Administrative (3.0%) 132,000

TOTAL ESTIMATED PROJECT COST $ 5,Z57,OOO

m-12 If the Lakeview Exchange is implemented, Option 2 is less costly than Option 3 by approximately $930,000. However, Option 3, which provides BBR water directly to the Shoshone Supply year-round, has many operational advantages over Option 2. Chief among these advantages are higher delivered water quality and much less transmission loss. In addition, the lower cost of Option 2 will be offset by additional treatment requirements. Therefore, Option 3 is the recommended system for a combined Lakeview/Shoshone Project conveyance.

WINTER SUPPLY

During the period when the Shoshone Conduit is shutdown for maintenance, water can be provided to the Shoshone Supply either by pumping from the Shoshone River or by utilizing the storage capacity of the existing City of Cody reservoirs. Implementing the storage option is over $2 million more expensive than is the pumping option. The principal component of cost in developing the storage option is the cost of dredging Alkali Lake. This is an extremely difficult parameter to estimate a cost for because of the uncertainty surrounding the disposal options for the lake spoil materials. The cost is also based on a commercial dredging operation, not on the City of Cody's present dredging program. Use of the City's dredge could have a significant impact upon the cost of this alternative.

Implementation of the river pumping option will be difficult from both construction and regulating aspects. The intake will require a Corps of Engineers 404 Permit and will most likely encounter stiff resistance from recreationists and perhaps environ mental groups. On the other hand, use of the storage system requires several improvements not costed for this feasibility study. These activities were assumed to be maintenance in nature and would be a required part of an ongoing physical improvements program. In addition, dredging the lakes will not be done without opposition. Several recreational groups and state agencies have voiced opposition to the City of Cody's ongoing program.

Use of a pumping station on the Shoshone River is the recommended alternative for supplying water during periods of winter shutdown in the Shoshone Conduit.

WATER TREATMENT

TREATMENT PROCESS

Recommendations of the Update Study

The July, 1984 "Update" Study recommended use of conventional treatment (floc culation, sedimentation, filtration) for the Shoshone Water Supply. This was based on the premise that raw water would continue to be diverted from Cody Canal to Markham Reservoir, and thence into the treatment plants, during the irrrigation season. Historically, high turbidities in Cody Canal have been experienced during May and June, with the result that the turbidity of water in Markham has oc casionally been 50 TU or more. Also, the selection of conventional treatment in the "Update" Study as opposed to direct filtration was based on furnishing some additional protection due to contaminants that enter Cody Canal through irrigation return flows, and also due to unquantified levels of algae and taste and odor prob lems in the supply. Also, when the Update Study was drafted, little was known about the levels of total potential trihalomethanes (TPTHM's) in the supply. There appears to be no reason to change the recommended process to direct

ill-13 filtration if the plan is still to divert raw water from Cody Canal for treatment during the irrigation season. The turbidities experienced in Cody Canal would disrupt a direct filtration process, and the concern over protection from con taminants in irrigation return flow is still valid.

If the winter supply pipeline were to be of sufficient capacity to handle summer peak flows to the plant, then water could be diverted directly from Buffalo Bill Reservoir into the treatment plant. Data collected during 1984 on water quality in Buffalo Bill Reservoir indicates that turbidities were in the range of 13 to 68 TU, which are also considered beyond the capabilities of a direct filtration pro cess. An additional concern would be algae in the water. On this basis, it appears that the alternative of routing water directly from Buffalo Bill Reser voir to the treatment plant by pipeline in the irrigation season would not affect the decision to utilize a conventional treatment process as opposed to direct filtration. The water quality in Buffalo Bill Reservoir also does not appear to support use of direct filtration.

THM and Taste/Odor Control

A limited amount of data collected since the Update Study indicates that po tentially high TPTHM levels exist in the existing raw water supply to the plant. Samples of water from New Cody Reservoir, Beck Lake, and Cody Canal all exhibited TPTHM levels significantly above 0.100 mg/l, (e.g. to 0.197 mg/l), and a sample of finished water from the plant was tested for THM's and also found to have levels above the primary drinking water standard (0.117 mg/l tested versus 0.100 mg/l standard). Some reduction (perhaps 20 to 40 percent) of THM percurser compounds will normally occur during the flocculation and sedi mentation processes, however, this cannot be predicted with any accuracy with out pilot testing of the treatment process. A conservative approach was there fore adopted in this analysis, and it was assumed that preozonation, at a mini mum dosage of 1.5 mg/l, would be required in order to meet the THM Standard, at least during the summer months when the Cody Canal is the source.

Summary Process Recommendations

A schematic illustrating the currently recommended treatment process is shown in Figure 9. Design criteria for application of the process to 11 mgd, 16.5 mgd, and 22 mgd are shown in Table 8.

USE OF EXISTING TREATMENT PLANT

In the Update Study, the alternatives examined for regional facilities at Cody included a Single Plant Alternative in which the existing treatment plant would be abandoned initially, and a Two Plant Alternative, in which the existing plant would be refurbished and modernized for continued service at 4.75 mgd. The ultimate capacity of regional facilities assumed for the Update Study was 16 mgd. The Single Plant Alternative envisioned an initial 12 mgd facility, expanded to 16 mgd in the year 2006. The Two Plant Alternative was based on a new plant of 8 mgd, plus the existing plant capacity of 4.75 mgd. In the year 2008, the new plant would be expanded to 16 mgd and the existing plant would be abandoned. Thus, in both alternatives, the ultimate required capacity of the new treatment facilities would be the same, but in the Two Plant Alternative, the initial new treatment facilities could be smaller.

m-14 RAW WATER t- - -Flow Measurement ~ - -Turbidity Measurement

PREOZONATION 1II~___ - OZONE

DECANT FROM LAGOONS S;- -- -+- -..,-..,------I._..-f---C AUSTIC SODA -- 5135 r ---- -a. !4--ALUM INITIAL MIX Ic--POLYMER I I - CHLORINE -~ 5130 I I a SULFURIC ACID

I I ------~---U__------~------.------~- --5125 I '- POLYMER (ALT.) HWC ELEV. I I _5_11_5_.0 __ ~-----"', ______-It------+-/ __ H_W_L ELEV. 5114.0 I ACTIVATED CARBON I .r -~------+I------I-I----~-~-- 5120 "" \ HWL ELEV. L - ~~-.---....II...------" /HWL ELEV. 5111.3 L ___ "h \ 5113.0 V -~-~---4H~-~------5115 FLOCCULA TION

T /LWL ELEV. 5105.3 OZONE CONTACT 14 BI\i:>'I'Ii:> ___ l----l ~~_ ----*+1--~------5110 I ./ MAX W.S. "--J TO CODY r( SEDIUFNTATION I...SZ.. ELEV. 5101.3 7 -1)- 'SYSTEM ,., WI '\. -+------t1i--t-t------++----- 5105 '::::--=+- "'- -" BAS INS , r----' ,,/ Ttl ,,'\. I ~f',. r;{' I SLUDGE TO ~ L \l -::"., ~ 1 -- --~H----H------i+-=-~M=,N=.W=.*S~===*-...-~.-jl'--h~~------5100 tiAGOONS SEDIMENTATION --==:-=-:-::-:-::~:::~==:::::.Jrr:==~l-\__ '- FLOCCULATION In n n ELEV. 5091.3 7 I --...... FROM NEW CODY ~ BASINS /----r-----'It--+-+------5095 ~ --- Turbidity Measurement RESERVOIR. CODY CANAL. ~ FLTER AID POLYMER OR WINTER SUPPLY PIPELINE. INITIAL MIX ~ ~ WASHWATER .. CHLORINE ~ EQUALIZATION PUMPS ------~---~~~~------___1tiIIrfII14p!J_t{=i'1'"'\--";JI-~~¥=-~___tt_~#===1J.~.----5090 •r III CLEARWELL ~--.J\.... ' __UM I II WASHWATER --,L..'" IU TO SHOSHONE 5085 EQUALIZATION!4- - FILTRATION WATER SUPPLY ELEV. 5087.8.-1 PROJECT PIPELINE BASIN 5080 Ie CAUSTIC SODA ~---Turbidlty Measurement ~ ---Flow Measurement HYDRAULIC PROFILE •• (at 22mgd)

CHLORINATION I4--CHLORINE

" FINISHED WATER TO CLEARWELL PROCESS SCHEMA TIC / HYDRAULIC PROFILE FOR SHOSHONE SUPPL Y REGIONAL WATER TREATMENT PLANT PROCESS SCHEMATIC FIGURE 9 TABLE 8 CODY ItEGIONAl. TREATMENT PLANT DESIGN CRITERIA

NEW PLANT ------_._-- EXISTING PLANT

UNIT PHOCESSI Initial Plant Initial Plant Ultimate Initial(e) CIIAHACTEnISTIC UNITS WII Plant Alternative W/l Plant Alternative (2 Plant Alternative) ------

Nominal Capacity mg" 16.5 11.0 12 4.75 Hydraulic Capacity mgd 16.5 34 Unknown Ozonation Gen~ration Capacity(a) Ihs/day lOO lO0(b) 300 (b) Nominal Contact Time mins. 10 10.5 10 0 Contactor Numbt'r cu. ft. 1 1 4 Contractor Voume (Total( cu. ft. 15,000 15,000 lO,OOO °

Initial Mix EIlNgy Input (G) l/sec. 900 900 900 900 (c) Typp pump pump pump pumpk) diffusion diffusion diffusion rliffusion Pump Power bhp 5 5 5 l.5 (c) H H H Flocculation I Bilsins (2 stage) number J 2 4 Compart ments per basin number ·1 4 4 Detention Time Icy Nominal Capacity minutes 30 30 30 Basin Depth ft. Il 12 Il Basin Width ft. 36 36 36 Basin Lf'ngth ft. 36 36 36 Total Water Volume CIl. ft. 46,700 31,100 62,200 Fl')Cculation Equipment: type 2 speed, l speed, 2 speed Horizontal vertical shaft vertical shaft vertical shaft paddle(c) number 8 R 16 Maximum Mixing Energy I/see. 80 80 80

Sedimentation Basins number 3 l 4 Detention Time at minutes 120 120 120 Nominal Capacity Over Flow Rate at gpm/sq.ft 0.75 0.75 0.75 Nominal Capacity Basin Depth ft. 12 12 Il Basin Width ft. 16 36 36 Basin Lf'ngth ft. 141 141 141 'j")tal Watf'r Voillme CII. Ct. lIn,ooo 121,OOO 244,000 CODY REGIONAL TREA1;MENT PLANT DESIGN CRffERlA (Continued)

NEW PLANT EXISTING PLANT .------~------

UNIT PROCESSI Initial Plant Initial Plant Ultimate Initial{e) CII AR ACTERlSTIC UNITS WII Plant Alternative WIl Plant Alternative {l Plant Alternative} ------.------Filters Quantity number 9 6 12 Filtration Ratp. grm/sq.ft. 6 () 6 Total Filter Area sq.ft. 1914 1278 2552 Width (each) ft. 10.5 10.Ii 10.5 Length (each) ft. ZO.25 ZO.25 ZO.25 Mf'dia type dual 11\1 a 1 flual Backwash Typt~ type self self splf Ilatp. gpm/sq.ft. 20 20 20 Surface Wash Type type fixed grid fixed grid fixed grid Rate gpm/sq.ft. 3 3 3

Treated Water Storage Storage Facili ty type Buried Buried Buried Heinforced Reinforced Reinforced Concrete Concrete Concrete Capacity Minimum MG 0.468 0.468 0.468 Operational MG 1.332 1.33l 1.332 Total MG 1.800 1.800 1.800 Detention Time at lOins. 41 43(d) 30 (d) Nominal Capacity and Minimum Storage Width x Lf'ngth ft. x ft. 100 x 178 100 x 178 100 x 178 Side Watf'r Depth ft. 13.5 13.5 13.5

Cody Pump Station

W~sh Water Equalization Basins number None Volume gal. 95,000 95,000 95,000 Heturn Flow Rate gpm 350 350 350 (pumped) Sludge Lagoons J.rlgoons number -1 -t 6 2 0pf'rating Depth (Max.) ft. (, (, 6 Total Surface Arf'a 5'1' ft. 101,000 68,000 lJ5,000 Total Volume cu. ft. 608,000 405,000 810,000 TABLE 8 CODY REGIONAL TREATMENT PLANT DESIGN CRITERIA (Continued)

NEW PLANT EXISTING PLANT

UNff PROCESSI Initial Plant Initial Plant Ultimate Initial(e) CHARACTERISTIC UNITS WII Plant Alternative W/Z Plant Alternative (Z Plant Alternative) ------

Chemical Design Criteria (@ Nominal Capacity) Aillm illS/hr. 230 153 306 Polymer lhs/hr. 14 9 18 Liquid Polymer lhs/hr. 28 18 36 H2S04 gal/hr. 5 3 6 Hydrated Lime Ihs/hr. 86 58 116 Chlorine lhs/hr. 550 368 736

Cody Pump Station Capacity (a) 9.32 4.'>7 14.34 4.75

H" I, Ozona ted Water Pump Station I 1-' Capadty (a) mgd Not required 4.75 Not required I

Notes

(a) with largest IInit out of service (h) ozonation of raw water for existing plant will be done at new plant (c:) mllllifkations at existing plant required to achieve this criterion. (,I) production from new plant and existing plant to pass through new clearwell on some occassions. (e) For "l Plant" alternative existing plant would be improved for service to approxmiately year 2012, and the abandoned. For" I Plant Alternative, existing plant would he ahancloned by year 1990. Since the Update Study, project water demands have been redefined to include a higher component of demand to meet City of Cody irrigation requirements. Maxi mum day demands in the year 2030 (and, therefore, ultimate capacity requirements of the treatment plant) are now estimated to be 22 mgd. However, average daily demand during the non-irrigation (winter) season are essentially the same as before and are projected to be approximately 6.5 mgd in the year 2030.

Costs for Single Plant and a Two Plant alternatives were reexamined based on the new demand projections, with the primary focus on the initial construction costs. The Single Plant Alternative used for analysis was initial construction of a 16.5 mgd plant, ultimately expandable to 22 mgd. The Two Plant Alternative consisted of 11 mgd of new plant construction (ultimately expandable to 22 mgd), in com bination with 4.75 mgd of capacity obtained from refurbishing the existing plant, for a total initial capacity of 15.75 mgd. Design criteria used in the analysis are shown in Table 8.

The results of the cost analysis are presented in Table 9. The total project costs for the Two Plant Alternative, at $13,427,000, is equivalent to a cost of $853,000 per mgd of capacity. The Single Plant Alternative, at a project cost of $14,534,000 has a unit cost of $881,000 per mgd of capacity. Therefore, the unit project costs of the two alternatives differ by approximately 3.3 percent. Considering the higher operational costs and very high nuisance value of two plants versus one plant, the Single Plant Alternative is recommended.

SITING

The area east of the existing plant, bounded on the southwest by Markham Reser voir and New Cody Reservoir, and on the north by Beck Lake, was examined for potential sites for the new water treatment plant. Hydraulic considerations are also a constraint in selection of the site.

The area north of the east end of New Cody Reservoir was considered to be the most attractive for siting the treatment plant. Sites further west were considered less desirable due to the narrowness and slope of the sites examined. Also, a site at the east end of New Cody Reservoir would facilitate access to a New Cody Canal turnout structure, since the canal bends northward at this point.

PLANT LAYOUT

Conceptual plant layouts are shown in Figure 10 and 11. As discussed under "Phasing" this layout lends itself to initial construction of either an 11 mgd plant or a 16.5 mgd plant, with later expansion to an ultimate capacity of 22 mgd.

PHASING AND COST CONSTURCTION OF PROJECT

For purposes of analysis, previous assumptions have involved initial construction of sufficient capacity for 15 to 20 years of service. Construction of less initial capacity would have the advantage of reducing initial capital outlay, and would permit expansion of facilities to match growth in demand as it occurs. The treatment plant lends itself to expansion in 5.5 mgd increments. An initial facility sized for 11.0 mgd would furnish adequate capacity to the year 1996 (according to demand projections) at which time an expansion to 16.5 mgd could be implemented, with a subsequent expansion to 22 mgd in the year 2013. This phasing plan is

m-I8 TABLE 9

COST ESTIMATE COMPARISON SINGLE PLANT VERSUS TWO PLANT (INITIAL CONSTRUCTION)

SINGLE PLANT TWO PLANT ALTERNATIVE

ITEM New Plant(a) New Plant(b) Exist. Plant(c)

Winter Supply Pipeline(d) $ 140,000 $ 140,000 New Reservoir Intake 30,000 30,000 New Canal Turnout and Piping 50,000 50,000 Ozonation Equipment/Building 758,000 758,000 At New Plant Ozonation Contact Basins 165,000 165,000 At New Plant Initial Mix/Flocculation 618,000 505,000 $ 142,000 Sedimentation 2,260,000 1,572,000 Sludge Lagoons 88,000 67,000 Filters 1,542,000 1,209,000 200,000 Washwater Equalization 402,000 402,000 Clearwell 970,000 970,000 55,000 Disinfection Facilities 100,000 83,000 53,000 Chemical Storage/Feed Facilities 280,000 245,000 69,000 Admin./Lab./Maint. Bldg. 230,000 230,000 Misc. Electrical & Instrumentation 250,000 200,000 Misc. Sitework and Yard Piping 450,000 400,000 Standby Power 75,000 75,000 Start-up by Contractor 30,000 30,000 Ozonated Water Pum~ Station 62 OOO(d) Ozonated Water Pipe ine 140,000 Cody Finished Water Pump Station 180,000 100,000 Finished Water Pipeline To Cody 140,000 140,000

Construction Subtotal $ 8,758,000 $ 7,371,000 $ 721,000

General Construction expenses (mobilization, bonds, etc.) (5%) 438,000 369,000 36,000

Subtotal $ 9,196,000 $ 7,740,000 $ 757,000

Contractor's Overhead and Profi t (15%) 1,379,000 1,160,000 114,000

Subtotal $10,575,000 $ 8,900,000 $ 871,000

Contingencies (15%) 1,587,000 1,336,000 130,000

Total Estimated Construction Cost $12,162,000 $10,236,000 $1,001,000

Engineering (16.5%) 2,007,000 1,689,000 165,000 Legal & Administrative 365,000 306,000 30,000

Total Estimated Project Cost $14,534,000 $IZ,Z31,000 $1,196,000

Notes (a) 16.5 mgd capacity (b) 11.0 mgd capacity (c) 4.75 mgd capacity (d) Constructed at new plant site

m-19 I .f / .~ ! T~- / " . \ II ( . 1\, :

'\ '. 'l;' I I;' ,. WASHWATER EQUALIZATION PUMP STATION CODY SYSTEM HIGH SERVICE PUMP STATION SHOSHONE - WASHWATER EQUALIZATION BASIN ~ LAKEVIEW

FINISHED WATER PIPELINE ~ PIPELINE TO CODY SYSTEM

RA W WATER SUPPLY PIPELINE ~=.::.::.:.:...... !::::=~

OZONE GENERATION BUILDING - -~-

BASIN __.J~ r."~"' .... r .. ".>W INITIAL MIX

LEGEND: 1. SHADED AREAS ARE FUTURE ADDITIONS TO INCREASE PLANT CAPACITY FROM 11 MOD TO 22 MGD.

FROM INTAKE IN NEW CODY RESERVOIR

SITE PLAN FOR SHOSHONE SUPPL Y REGIONAL WA TER TREA TMENT PLANT FIGURE 11 illustrated and compared with the alternative of constructing an initial 16.5 mgd plant in Figure 12 and Table 10.

As shown in Table 10, the costs of constructing an initial 11 mgd facility are approximately $2.3 million (16.3 percent) less than the costs of constructing an initial 16.5 mgd facility. This phasing alternative should be considered if initial project cost and cash flow are issues in implementing the project. It should be noted that the cost shown for an 11 mgd facility in Table 9 is slightly less ($190,000) than the cost shown previously in Table 8 for an 11 mgd facility. This is due to the fact that the costs shown in Table 8 for the 11 mgd new plant included ozonation facilities at the new plant which were adequate for treatment of 16.5 mgd. In Table 10, the initial ozonation facilities are sized for 11 mgd initial capacity.

SUMMARY AND RECOMMENDATIONS

It has been previously recommended that the plant influent water not be drawn from the Cody Canal because of the loss of water in transmittance and the resulting degradation in quality. While this recommendation does result in higher costs for the BBR diversion, they can be offset by deleting certain treatment elements that have been described previously, namely ozonation. Removing this item from the treatment process will result in an approximately savings of $1.5 million in project costs for a facility of 16.5 mgd capacity. Operational costs of several tens of thousands of dollars per year will also be avoided.

It is recommended that a facility of 16.5 mgd capacity be constructed. This facility would obtain water directly from BBR (avoiding transmittance in Cody Canal) and would not utilize ozonation.

TRANSMISSION PIPELINE

COMMUNITIES SERVED AND ALIGNMENT

The treated water pipeline was originally proposed to serve Cody, Powell, Byron, Cowley, Frannie, Deaver, Lovell and rural areas along the pipeline alignment. However, Cowley has recently drilled a new well with excess capacity Byron is currently connecting to that source. In addi tion, Frannie and Deaver are currently engaged in jointly drilling a new well to serve those communities. It is uncertain what future course of action those communities may take. At this time, the only community which has expressed a desire not to be considered for the Shoshone project is Cowley. Therefore, for the purposes of this report it is assumed the transmission pipeline will be sized for all communities along the alignment men tioned above, excluding Cowley.

The previous Level I investigation recommended an alignment which generally parallels U.S. Hwy 14 from Cody to Lovell with two alternative routes along the corridor from Powell to Byron. The more northerly route went through Garland and traversed across approximately six miles of private oil field. Acquisition of oil field right of way and general access and topography obstacles indicated the southerly alignment to be a better choice. Further field reconnaissance was conducted along the preferred alignment and localized refinements and adjustments made. The resulting best apparent alternative pipeline route is shown on Figure 13.

m-20 30~------~

PEAK DAILY DEMAND, INCLUDING IRRIGATION WATER FOR CODY

EXPANSION 25 TO 22 MGD

CONSTRUCT NEW PLANT, 20 ABANDON t:XISTING EXPANSION PLANT TO 16.5 MGD t

PEAK DAILY DEMAND W /0 IRRIGATION WATER FOR CODY

AVG. DAILY DEMAND

W'~:O~I:RR:I:G:A=TI:O:N~W::AT:E:R~:;~ ____:-.::~~ --.... --- .... -- CAPACITY OF _ ------~ ASSUMED LOW WINTER MONTH EXISTING PLANT AVG. AT 0.67 TIMES AVG. ANNUAL NON-fRRIGAnON DEMAND

1980 1990 2000 2010 2020 2030

YEARS

PROJECT PHASING PLAN FOR SHOSHONE SUPPLY REGIONAL WATER TREA TMENT PLANT FIGURE 12 TABLE 10

COST ESTIMATE FOR INITIAL CONSTRUCTION OF CODY REGIONAL WATER TREATMENT PLANT

16.5 MGD 11.0 MGD CAPACITY CAPACITY

ITEM

Winter Supply Pipeline $ 140,000 $ 140,000 New Reservoir Intake 30,000 30,000 New Canal Turnout and Piping 50,000 50,000 Ozonation Equipment/Building 758,000 608,000 Ozonation Contact Basins 165,000 125,000 Initial Mix/Flocculation 618,000 505,000 Sedimentation 2,260,000 1,572,000 Sludge Lagoons 88,000 67,000 Filters 1,542,000 1,209,000 Washwater Equalization 402,000 402,000 Clearwell 970,000 970,000 Disinfection Facilities 100,000 83,000 Chemical Storage/Feed Facilities 280,000 245,000 Admin./Lab./Maint. Bldg. 230,000 230,000 Misc. Electrical & Instrumentation 250,000 200,000 Misc. Sitework and Yard Piping 450,000 400,000 Standby Power 75,000 75,000 Start-up by Contractor 30,000 30,000 Cody Finished Water Pump Station 180,000 100,000 Finished Water Pipeline To Cody 140,000 140,000

Construction Subtotal $8,758,000 $ 7,181,000

General construction expenses (mobilization, bonds, etc.) (5%) 438,000 359,000

Subtotal $9,196,000 $ 7,540,000

Contractor's overhead and project (15%) 1,379,000 1,131,000

Subtotal $10,575,000 $ 8,671,000

Contingencies (15%) 1,587,000 1,301,000

Total Estimated Construction Cost $12,162,000 $ 9,972,000

Engineering (16.5%) 2,007,000 1,645,000 Legal & Administrative (3.0%) 60,000 299,000

Total Estimated Project Cost $14,ZZ9,000 $11,916,000

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• G~, ... Pit TlNll q'o_~~WTP\" ~ ", o 4 ! ST A.4t6e~O-~·- -' ';:'1 scale miles (" -~ \' /. \- / PROPOSED SHOSHONE MUNICIPAL PIPELINE CORRIDOR FIGURE 13 CAPACITY AND HYDRAUUCS

The pipeline is sized to meet the maximum demand in the year 2030 for the communities indicated above. The selected alignment allows gravity flow from an elevation of 5100 at the clearwell of the proposed water treatment plant in Cody to El 3855 in Lovell. It was determined that one pressure reducing station would be needed just upstream of Powell to maintain pipeline pressures under 300 psi at static conditions. The pipeline was sized and hydraulic gradeline generally set to maintain a delivery pressure of 40 to 45 psi to communities along the route.

System operating procedures and pressures were analyzed in more detail for Powell and Lovell, as those communities have significantly larger demands, and it would be beneficial to enter those systems at normal operating pressure, if economical and practical. Lovell currently maintains a system pressure of 68 psi at the pumped discharge from their water treatment. Approximately the last 6500 feet of transmission pipeline must be oversized from 8-inch to 10-inch in diameter to accommodate the higher Lovell system pressure. The small additional incre mental cost would be offset by the power savings over the project life of re pumping the water in Lovell. Powell utilizes wells which pump into a central 1,000,000 gallon storage reservoir, which is then pumped to system pressure through a booster station. The system pressure at Powell is approximately 72 psig and upstream transmission piping would have to be increased from 20-inches to 24-inches in diameter for a distance of approximately 25,000 feet to allow discharge at system pressure. In addition, most of Powell's storage is at a hy draulic grade line of 4417 which prevents its utilization, unless a break in pres sure occurs at discharge from the transmission pipeline. Economics and the problem of storage utilization indicate that discharge at Powell should not be at distribution system pressure, but should discharge to the 1,000,000 gallon reser voir instead.

APPURTENANCES

There are a number of appurtenances normally associated with a transmission pipeline of this length. Such appurtenances include isolation valves, blowoffs, air vacuum-release valves, pressure reducing station(s), and corrosion testing cathodic protection stations.

Isolation valves would be provided at all service turnouts, jacked casings, major drainage crossings, and located along the pipeline at approximate 10,000 foot intervals. These facilities would allow for draining a reach of 20-inch diameter pipe in approximately 3 hours at a rate of 1000 gpm. A single pressure reducing station would be located at Sta. 1274+00 to maintain pipeline pressure below 300 psi. Sufficient data is not available to completely determine the extent of cor rosion protection necessary for the pipeline. A comprehensive corrosion survey must be provided prior to proceeding to design to optimize the amount of cor rosion protection needed. Preliminary estimates have been based on experience with similar installations.

Another appurtenance or factor to consider will be chlorination prior to dis charge to individual distribution systems. Although treated water would be chlorinated at Cody, it is unlikely that sufficient uniform residual will be main tained throughout the pipe length for discharge directly into distribution systems along the route without rechlorination. Most of the communities' existing sup-

ID-22 plies are currently chlorinated. Some of these chlorination systems will require modification in the form of chlorine water supply booster pumps, etc. to allow rechlorination. Also, transmission pipeline water would have to be delivered to distribution system chlorination points or separate chlorination systems installed if pipeline discharge is to another point in the system.

TRANSMISSION PIPELlNE COST ESTIMATE

A project cost estimate summary for the transmission pipeline is as shown on the following Table 11. Some clarifications should be made regarding the transmission line cost estimate:

• Pipeline costs include extension to Powell and 5,000 feet of 8-inch pipe to rural communities, but does not include extension to Frannie and Deaver, or outlying areas a significant distance from the transmission pipeline.

• Turnouts were estimated for Powell, Ralston, Cody Rural, Powell Rural, Byron, and Lovell. Cody water would be supplied directly from the regional WTP. No turnout estimate was provided for Frannie/Deaver.

• Costs for major river and drainage crossings were based on shield and dredge methods of crossing. These project costs may be reduced by approximately $350,000 if suspended crossings utilizing existing highway bridges proves feasible. Initial analysis and contacts appear to indicate that this type of crossing will be applicable.

m-Z3 TABLE 11

TRANSMISSION PIPELINE COST ESTIMATE

Estimated Item Quantity Amount

Pipeline 250,000 ft.:!: of $ 8,501,000 8-24 inch dia. Blowoffs 24 55,000 Pressure reducing station 1 29,000 Air vacuum-release valves 27 70,000 Isolation valves 60 235,000 Jacked casings 610 feet 197,000 Corrosion test and protection stations 80 69,000 Bridge & drainage crossings 14,000 ft 831,000 Rock excavation 20,000 cy 1,487,000 Pressure reducing stations and meters at turnouts 6 137,000 Chlorination facilities construction/ improvements Is 75,000

Construction Subtotal $ 11,686,000

General construction expenses (mobilization, bonds, etc.) (5%) 584,000

Subtotal $ 12,270,000

Contractor's overhead & project (15%) 1,841,000

Subtotal $ 14,111,000

ROW acquisition 4500 If 9,000

Subtotal $ 14,120,000

Contingencies (15%) 2,118,000

Total Estimated Construction Cost $ 16,238,000

Engineering (16.5%) 2,679,000 Legal & Administrative (3.0%) 487,000

TOTAL ESTIMATED PROJECT COST $ 19,404,000

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