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Laramie, WY 82071

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Laramie, WY 82071

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EXECUTIVE SUMMARY

PINE BUTIE WATER SUPPLY PROJECT

INTRODUCTION

The Pine Butte Improvement and Service District is located in portions of Sections 25 and 26, Township 52 N, R 73 W in Campbell County approximately 11 miles to the north of the City of Gillette along U.S. Highway 14/16. Pine Butte Improvement and Service District (PBI&SD), comprised of the Pineview Ranches, Bredthauer Subdivision and Bredthauer West Subdivision, initially totalling 33 property owners, was formed in 1991. Currently, the water supply needs for the people in the district are provided by fourteen domestic wells, hauling City of Gillette water to cisterns, and/or by a community well. There is an existing small central water system in the district consisting of one 710 foot deep community well, pressure storage and a distribution system that serves 14 lots.

Water problems have plagued the people of the district for more than ten years. Most of the domestic wells are completed in the Tertiary Wasatch Formation, an aquifer generously characterized as producing a marginal to low quality, highly mineralized, water and usually containing significant quantities of gas. The Community well, although completed in the upper sands of the Tertiary Fort Union Formation exhibits water quality very similar to that produced from the Wasatch Formation. Further investigation revealed that the Community well's steel casing has deteriorated allowing the Wasatch water to co-mingle with the higher quality Fort Union Water.

PBI&SD received funding in 1993 from the Wyoming Water Development Commission (WWDC) for a Level II project to develop a groundwater source to meet the water supply needs of the district. Wester-Wetstein & Associates, Inc., in conjunction with Soda Butte Services, Inc. was selected by the WWDC to provide geological and engineeing services for this Level II project. Work began in May, 1993 with the development of well designs and preparation of specifications for well drilling, construction and development.

This summary report was prepared to provide a brief overview of the results of the well drilling and testing program, conceptual design and cost estimates associated with the completion of the Pine Butte No. 1 Well project.

PHASE I • WELL SITING AND CONSTRUCTION

Well Construction

The contract for the design and construction of the Pine Butte No. 1 well was awarded in May of 1993. Contract specifications were prepared for a telescoped well design, with

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1200 feet of pump chamber grouted in place and 1600 feet of casing and well screen hung by a liner-hanger-packer assembly placed within the pump chamber. A 8%-inch diameter pump chamber was selected to be consistent with the new Fort Union well design regulations currently being written and considered for implementation by the State Engineer's Office.

Contractor mobilization began on August 6, 1993. A 61A-inch diameter pilot hole was extended to a depth of 200 feet. The 61A-inch pilot hole was reamed to a diameter of 143A-inch to a depth of 140 feet below ground level (bgl). The upper 136.5 feet of sands and mudstones were cased off with 123A-inch outside diameter (0.0.) steel casing. The remaining 60 feet of slim hole was reamed to 11 .. inches in diameter and an 11 .. inch diameter borehole was advanced to a depth of 1206 feet below ground level (bgl). The drilling of this interval was typified by a continuous loss of drilling fluid. Although circulation was never lost, much time, effort, bentonite drilling gel and cellophane flakes (lost circulation material) were required to maintain circulation of the mud system.

Following a logging run, 970 feet of 8%-inch 0.0. steel casing was placed in the well. Specifications called for 1200 feet of SISAJ-inch casing, however, the casing became stuck (believed by the driller to be differentially stuck) at the 970 foot depth. The 8%-inch casing was cemented in place and the remainder of pump chamber completed by installing and cementing in place 7-inch 0.0. welded steel casing from 957 feet to 1208 feet bgl. After allowing the cement grout to set, a 61A-inch diameter borehole was advanced to a depth of 2809 feet. Geophysical logs were then completed to clarify lithologic and water bearing characteristics.

200 feet of well screen was positioned opposite numerous sandstones identified by the geologic and geophysical methods. Shale baskets were placed above each well screen to aid in keeping the screens free of fine grained material which might cascade down the annular space between the 4V2-inch diameter casing and 61A-inch diameter borehole. Centralizers were also placed above each screened interval to keep the casing string centered in the borehole. Table 1 is a summary of the pertinent well information and well materials used by the Contractor in the completion of the Pine Butte No.1 well. Figure 1 shows a schematic of the formation lithology, geophysical logs, and "As-Built" construction details of the well.

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lu w u. z J: t-D.. W C

2900

FORMATION lITHOlOGYIWElllOG

UPPER iit~12=iiii WYOOAK

LOWER WYODPJ(

a: w en :e w :e a: w > iC w :J

Z 0

0 Z 0

i= .... « :?E a: 0 U.

Z O Z ::l I-a: 0 w

oJ a: U. ~w cn lXl 0:1 IB~ oJ

--

CONSTRUCTION DETAilS

SWL-542FT.

SURFACE CASING, 12 3f4-INCH O.D., ASTM AS3, GRADE B, WELDED STEEL CASING SET TO A DEPTH OF 136 FEET

14 3/4-INCH DIAMETER BOREHOLE

11-INCH DIAMETER BOREHOLE

VOID IN CEMENT SEAL DUE TO HEAVY LOST CIRCULATION ZONES IN THE WYODAK COAL SEAMS

8 S/8-INCH O.D., API K-SS, 38 LBIFT THREADED STEEL CASING SET TO A DEPTH OF 970 FEET

NEAT CEMENT GROUT, UGHT CEMENT FOLLOWED BY 200 FEET OF TYPE Q

7-INCH 0.0., API K-SS, 20 LB/FT, WELDED STEEL CASING SET FROM 9S7 FEET TO 1208 FEET

BAKER-HUGHES UNERfHANGERIPACKER ASSEMBLY SET AT A DEPTH OF 1143 FEET

61/4-INCH DIAMETER BOREHOLE

SHALE BASKET SET BELOW SCREENED SECTION IN AN EFFORT TO DECREASE METHANE GAS MIGRATION FROM COAL SEAM BELOW

SHALE BASKET AND CENTRAUZER PLACED ABOVE EACH SCREEN SECTION

4 1/2·INCH 0.0., API J-SS, 10 LBIFT, THREADED STEEL UNER

4-INCH PIPE SIZE, V·SlOT, CONTINUOUS WIRE-WOUND, DOUBLE EXTRA STRONG, 15 SLOT STAINLESS STEEL SCREEN MANUFACTURED BY JOHNSON WELL SCREENS; SCREENS PLACED AT:

1524 FEET TO 1594 FEET, 1906 FEET TO 1946 FEET, 2026 FEET TO 2066 FEET, 2126 FEET TO 2146 FEET, 2656 FEET TO 2676 FEET, AND 2790 FEET TO 2800 FEET

THREADED STEEL CAP AT A DEPTH OF APPROXIMATELY 2810 FEET

EXPLANATION

COAL

WESTCR·WETSTCIN. ASSOCIA TCS, INC. OONSUt.TINIS II EHGtNEE1fNtJ MID HYDIIOOEOI.OOY

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UJ Soda Butte Services, Inc.

~ G.==;j

MUDSTONE AND SMALL SAND LENSES

WYOMING WATER DEVELOPMENT COMMISSION CHEYENNE, WYOMING

e··········· trrtrr SANDSISANDSTONE

PINE BUTTE NO.1 AS-BUILT DIAGRAM

D SHALE/CLAYSTONE

FIGURE 1

Owner:

DEQ Permit to Construct Number:

State Engineer Permit Number:

Location:

Surface Elevation:

Total Depth:

Formations:

Hole Diameter:

Casing:

Drilling and Completion Dates:

Testing Dates:

Engineering and Geology:

Drilling Contractor:

Cementing Contractor:

Geophysical Logging Contractor:

TABLE 1

Well Summary Pine Butte No. 1 Well

Wyoming Water Development Commission

93-199

U.W.91809

SWV4, NWV4, Section 25, Township 52 North, Range 73 West

Approximately 4500 feet (MSL)

2820 feet below ground surface

o - 442 ft = Wasatch Formation 442 - 2820 ft = Fort Union Formation

o - 140 ft = 14%-inch 140 - 1208 ft = 11-inch 1208 - 2820 ft = 6V4-inch

o - 136 ft =

+2 - 970 ft =

957 - 1208 ft =

1143-2810ft

123A-inch 0.0., ASTM A53, Grade B, welded steel casing 8lVa-inch 0.0., API K-55, 36 Ib/ft, threaded steel casing 7-inch 0.0., API K-55, 20 Ib/ft, welded steel casing 4Y2-inch 0.0., API J-5S, 10 Ib/ft, threaded steel liner with 4-inch pipe size, v-slot, double extra strong, 15 slot stainless steel screen (Johnson Well Screens) threaded to the steel liner

August 13, 1993 to September 29, 1993

October 7, 1993 to October 14, 1993

Wester-Wetstein & Associates, Inc Laramie, Wyoming and Soda Butte Services, Inc. Upton, Wyoming

Weston Engineering, Inc. Upton, Wyoming

Equipment: Portadrill TK with 5Y2-inch by 12-inch mud pump

Sun Cementing Services Inc., Gillette, Wyoming

Goodwell, Inc., Upton, Wyoming

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Well Development

Following installation of the well screen and liner, the well was thoroughly flushed with 250 barrels of fresh water through the screens to purge the well of the lost circulation material prior to setting the packer. Well development commenced after the installation of the packer. Development began by high-pressure jetting of the screens with clear water and proceeded with air-lift pumping and surging with a bailer opposite the screened sections. Total development time was approximately 35 hours. The produced water was clear to slightly milky with no trace of sand at the conclusion of development.

Well and AquHer Testing

A step-drawdown test was performed to determine well performance characteristics, while aquifer characteristics were determined using constant-rate pumping and recovery tests. Well performance testing determined that the well efficiency was high, nearly 100%

efficient. Aquifer performance testing determined that Fort Union is a confined aquifer system (the static water level is well above the initial screened interval), the near well transmissivity was approximately 1500 gallons per day per foot of drawdown (gpd/ft), while the effective transmissivity after about 2112 hours dropped off to approximately 890 gpd/ft.

Well Interference

The vertical distance separating the screened sand intervals in the Pine Butte well from those of the nearby water wells approaches nearly 800 feet; this interval consists predominantly of shales and clay_ This material effectively seals the lower sands from the upper sand and precludes any upward leakance of groundwater from the lower Fort Union sands (in which Pine Butte No.1 is completed) to the upper producing Fort Union sands. Until another water well is drilled in the area of the Pine Butte No. 1 well and is completed in the same sand lenses or at a similar depth as that of the Pine Butte well (increasing the chances that the sands are in hydraulic communication with the sands in the Pine Butte well), there is little potential impacts posed by this well to other water wells in the area or visa versa.

The discharge/drawdown relationship of the Pine Butte No.1 well over the 20 year design period suggests that the aquifer system developed by the Pine Butte No. 1 well can theoretically meet the average daily demand and the maximum daily demand.

Water Quality

Comparison of the laboratory analyses with U.S. Environmental Protection Agency (EPA) primary and secondary drinking water standards reveals that the water developed by the Pine Butte well exceeds the existing primary standard for radium, however, but is well within the proposed standards. EPA has proposed increasing the maximum contaminant

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level (MCl) for radium 226 to 20 pCill and radium 228 to 20 pCi/1. Several treatment methods can be used to remove radium from the groundwater, these are reverse osmosis, ion exchange, lime-soda softening and the addition of preformed hydrous manganese oxides to the groundwater. Prior to initiating any design costs for radium removal, the district should first obtain another water sample and have it analyzed for radium and radon. If the levels of contaminants in this sample exceed the current EPA standards, then a representative of EPA should be contacted to ascertain when and if the proposed radionuclides standards will be promulgated, in order to determine if the district will need to design the treatment facility for the removal of radium prior to the implementation of the proposed new regulations.

The developed water from Pine Butte No.1 also exceeds the Secondary EPA parameters for coliform bacteria, total dissolved solids, iron, color and turbidity. With the exception of the coliform, these other parameters are associated with the taste and aesthetic qualities of the water and will pose no health problems. The test for total coliform failed, not because of the quantity of coliform found in the sample, but because the sample could not be analyzed due to some mineral deposits (source unknown). Additional bacteriological analyses found a moderate occurance of sulfur bacteria in the water, but no indication of the presence of iron bacteria.

During the pump tests, a consistent supply of gas (most likely methane gas produced from the coal seams present in the Fort Union Formation) was produced. The dissipation of this gas will need to be addressed in the final design of the Pine Butte water system.

PHASE II - CONCEPTUAL DESIGN AND COST ESTIMATES

Conceptual Design

The conceptual design was limited to the design of the pump and pumping equipment, collection line, treatment facility and the transmission line from the treatment building to the storage tank. The remainder of the Pine Butte Water System (transmission line to the distribution system, distribution system and storage facilities) has already been designed and the appropriate funding secured from sources other than the Wyoming Water Development Commission.

Well completion should consist of a setting a 50 gpm submersible pump with a 20-horsepower motor to a depth of 750 feet. A check and drain valve will be installed above the pump. Two airlines will be installed from the surface to the top of the pump to monitor water levels. Wellhead construction of the Pine Butte well will incorporate a pitless adapter allowing the pumped water to be conveyed through pipes buried underground, thus preventing freezing problems.

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Water from the well will be collected in a 4-inch diameter collection line and delivered to the treatment facility. The treatment facility will house the well pumping controls, meters and the chlorination facility. Chlorination of the well water will be via a hypochlorite injection system. A sodium hypochlorite system is recommended because it can be delivered as a premixed liquid in barrels to the site, or purchased as domestic bleach products (usually a 5% chlorine solution), thus eliminating the problems associated with mixing powdered hypochlorite.

The installation of the transmission line will involve a 4-inch pipe buried to a depth of 6 feet running from the control building (carrying the chlorinated water) to the storage tank to allow for proper chlorine contact time for adequate disinfectant treatment. The tank site is located in the immediate vicinity of the well and control building, limiting the length of transmission line to less than 100 feet. PVC and ductile iron pipe are acceptable alternatives for the proposed transmission system.

Conceptual Design Cost Estimates

Cost estimates for the completion of the Pine Butte Water Supply System were developed based on current projections from contractors and actual expenditures for similar systems recently completed around the State. Engineering cost and construction contingencies were developed in accordance with standard percentages currently used in WWDC budget projections. Table 2 presents the total project cost estimates generated.

Table 2 Pine Butte Well Completion Estimates

ITEM

Pump, Motor (20 Hp), Controls, Drop Pipe, Airlines and Wire

Pitless Adapter

Control Building, Valves, Meter, Piping and Chlorination Unit

Exterior Piping (100 L.F.)

Subtotal

Engineering

Contingencies (15%)

Total

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COST

$15,000.00

$3,000.00

$38,800.00

$3,500.00

$60,300.00

$11,000.00

$9,045.00

$80,345.00

Operation and Maintenance Costs

In addition to the capital construction costs outlined above, long-term operation of a water system will require qualified operation and continued maintenance. Table 3 shows projected operation and maintenance costs on a yearly basis.

Table 3 Pine Butte Improvement & Service District

Operation and Maintenance Costs

ITEM

Administrative Expenses

Legal

Accountant

Billing

System Operator

*Electrical Power

Equipment Repair - Replacement

150/0 Contingency

COSTIYEAR

$300.00

$1,000.00

$1,200.00

$3,000.00

$6,200.00

$1,000.00

Subtotal $12,700.00

$1,900.00

Total 0 & M Costs $14,600.00 * Costs based upon 0.89 water horsepower per kilowatt-hourlhour

Discharge Rate of 50 gpm

Project Financing

Water Horsepower of 20 Average Da~y Demand of 28,320 gaUons (189 users) (HKM, 1992) 6¢ per kilowatt-hour plus $120.00 annual demand fee

Monies for the completion of the Pine Butte No.1 well may be potentially available from the Wyoming Water Development Commission. This financing would be based upon a 670/0 grant and 33% loan split. It is assumed the loan will be amortized over a twenty year period at a 40/0 annual interest rate. Purchase of the water developed from the Pine Butte No. 1 well (well to be owned by the State of Wyoming and a contract signed allowing PBI&SD to purchase 30 acre-feet per year) will be based upon an annual payment equal to 50% of 33% of the State's actual cost of constructing the Pine Butte No. 1 well amortized over a twenty year period at a 4% annual interest. An annual

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breakdown of these costs are shown in Table 4.

Table 4 Total Annual Expenses

Completion and Operation of Pine Butte Well No. 1

ITEM COST

Completion of Well No. 19

Retirement of Well Construction Debt

$1,950.94

$1,504.64

Operation and Maintenance

Monthly User Costs

$14,600.00

Total $18,055.58

The monthly user costs associated with the annual costs shown in Table 5 will decline as the number of users increases. Based upon the 28 single family dwellings currently comprising the PBI&SD, the monthly residence cost will be $53.74 ($54.00). Basing the monthly costs on the 59 residences on which the system was designed, the monthly cost per residency would be $25.50. It must be stressed that these costs do not take into account the cost associated with retiring the potential debt for construction of the storage and distribution systems.

Conclusions and Recommendations

The Fort Union aquifer penetrated by the Pine Butte No. 1 well is composed of complex interbedded sandstone, mudstone, clay and coal layers. The effective transmissivity experienced by the well is approximately 800 gpd/ft. Initial transmissivities of 1,500 gpd/ft were observed during the constant-discharge pump tests, which ultimately decreased to 800 gpd/ft as the more permeable sand lens(s) terminated laterally. The water developed from the Pine Butte No.1 well is a sodium-bicarbonate water and very soft. Water quality from the well is within EPA primary and secondary drinking water standards with the following exceptions: radium exceeds the current standards very slightly, but is well within the proposed standards; total dissolved solids is slightly over the standard; total coliform failed due to sample contamination; iron exceeds the standard by nearly 300 percent; color and turbidity. The completion of the Pine Butte well project consists of the completion of the well (pump, motor, drop pipe, pitless adapter, etc. installation), the construction of the control building (including chlorination system, piping, valves and other appurtenances) and the required collection and transmission line to transport the water

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from Pine Butte No. 1 to the control building and on the storage. The per residence monthly cost associated with this construction, the debt retirement of the well, and the operation and maintenance of the system is approximately $54.00 (based upon 28 residences).

To save engineering and possibly construction costs, this project should be designed and bid in conjunction with the storage and distribution system. It is r~commended at this time that the groundwater be treated by chlorine disinfection (sodium hypochlorite injection) only_ Due to the uncertainty of the EPA regulations with respect to the promulgation of the proposed radionuclide standards, designing and constructing a treatment process for radium removal would, at this time, be premature. It is strongly recommended that additional analyses be made to determine if, indeed, radium does consistently occur in the groundwater developed by the Pine Butte well at the level originally reported.

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