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1 This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library. For additional information about this document and the document conversion process, please contact WRDS at wrds@uwyo.edu and include the phrase Digital Documents in your subject heading. To view other documents please visit the WRDS Library online at: Mailing Address: Water Resources Data System University of Wyoming, Dept E University Avenue Laramie, WY Physical Address: Wyoming Hall, Room 249 University of Wyoming Laramie, WY Phone: (307) Fax: (307) Funding for WRDS and the creation of this electronic document was provided by the Wyoming Water Development Commission (

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3 TABLE OF CONTENTS 1 INTRODUCTION Summary of Project Work Summary of Recommendations Airport No Well No Pony Creek Road North Waterline Loop Contractor Fees and Work History TEST WELL NOS. 1, 2 AND AIRPORT NO Geology and Well Construction Hydraulic Testing Step Rate Pumping Test Constant Rate Pumping Test Design Pumping Rate Water Quality Completion Recommendations WELL NO Geology and Well Construction Hydraulic Testing Step Rate Pumping Test Constant Rate Pumping Test Design Pumping Rate Water Quality Completion Recommendations Well Completion Control and Treatment Building Connection to the Existing System SCADA Control Cost Estimates PHOTO PLATES PONY CREEK RD. NORTH WATER LINE LOOP Cost Estimates REFERENCES Stetson Engineering, Inc. Dubois Test Well Drilling Project Page i

4 LIST OF TABLES 4-1 Well Completion and Connection to Existing Water System Cost Estimate 4-2 Well Completion and New Tank Transmission Line Cost Estimate 6-1 Pony Creek Road Water North Line Loop Cost Estimate LIST OF FIGURES 1-1 Vicinity Map and Borehole Locations 1-2 Pony Creek Road North Water Line Loop Area of Interest 1-3 Modeled North Water line Loop 2-1 Test Well No. 1 Borehole Log 2-2 Test Well No. 2 Borehole Log 2-3 Test Well No. 3 Borehole Log 3-1 Airport No. 1 As-Built Construction Log 3-2 Airport No. 1 Step Rate Test Hydrograph 3-3 Airport No. 1 Step Rate Test Semi-Log Plot 3-4 Airport No. 1 Specific Drawdown Plot 3-5 Airport No. 1 Constant Rate Test Hydrograph 3-6 Airport No. 1 Constant Rate Test Log-Log Plot 3-7 Airport No. 1 Constant Rate Test Semi-Log Plot 3-8 Airport No. 1 Constant Rate Test Horner Plot 3-9 Airport No. 1 Design Rate Analysis 4-1 Well No. 11 As-Built Construction Log 4-2 Well No. 11 Step Rate Test Hydrograph 4-3 Well No. 11 Step Rate Test Semi-Log Plot 4-4 Well No. 11 Specific Drawdown Plot 4-5 Well No. 11 Constant Rate Test Hydrograph 4-6 Well No. 11 Constant Rate Test Semi-Log Plot 4-7 Well No. 11 Constant Rate Test Normalized Semi-Log Plot 4-8 Well No. 11 Constant Rate Test Derivative Plot 4-9 Well No. 11 Constant Rate Test Model Fit 4-10 Well No. 11 Design Rate Analysis 4-11 Well No. 11 Field Water Quality Parameters 4-12 Well No. 11 Water Temperature 4-13 New Well 11 recommended Connection to Existing Water System 6-1 Test Well No. 1 Borehole Log 6-2 Test Well No. 2 Borehole Log Stetson Engineering, Inc. Dubois Test Well Drilling Project Page ii

5 PHOTO PLATES Nos. 1 through 5 LIST OF APPENDICES A B C D E F G H SEO Permits Contractor Fees and Work History Test Well No. 1 Pumping Test Results & Recommendations Airport No. 1 Hydraulic Analysis Worksheets Airport No. 1 Water Quality Reports Well No. 11 Construction Data Well No. 11 Hydraulic Analysis Worksheets Well No. 11 Water Quality Reports Stetson Engineering, Inc. Dubois Test Well Drilling Project Page iii

6 1 INTRODUCTION This report documents the Dubois Test Well Drilling Project completed as an extension to the Dubois Level II Study. The Level II Study report (Stetson Engineering, Inc. 2004) identified candidate sites for test well drilling to develop additional water supply for the Town. The Dubois Test Well Drilling Project conducted the work to install and test the wells during Summer and Fall Figure 1-1 provides a vicinity map showing the borehole locations. The project funding for the extended Level II Study was provided by the Wyoming Water Development Commission (WWDC). Kevin Boyce, PG, was the WWDC project manager. Engineering services for the project were provided by Stetson Engineering, Inc. with Western Groundwater Services, LLC working as a sub-consultant. Stetson Engineering, Inc. worked from offices in Riverton and Gillette. Western Groundwater Services is located in Bozeman, Montana. 1.1 Summary of Project Work The first phase of the project installed three test wells, designated as Test Well Nos. 1, 2 and 3. Test Well Nos. 1 and 2 were located on the parcel of existing Well No. 8, and were used to locate a new production well of larger capacity at this site. Test Well No. 3 was drilled on the K-8 School property (Fremont County School District) in the Horse Creek drainage to explore for a new alluvial aquifer well at this location. Good conditions identified in Test Well No. 1 led to the construction and testing of a new production well, designated as Well No. 11. This well was drilled at 16-inch diameter into the alluvial aquifer and will be a production well for the Town. A test well was also constructed near to the terminal of the Dubois Municipal Airport, with the intentions of finding water to serve the airport, as presently water is hauled to this facility. A test well was installed into the shallow aquifer and found to be sufficient for the airport water needs. Additional to the installation of the wells the Town of Dubois requested that some additional water system modeling be completed for an area North of Town. The area is along pony Creek Road (Tappan Creek drainage area) and has been considered as a possible site for the new High School and possible Town expansion. Figure 1-2 provides a map of the area of interest. 1.2 Summary of Recommendations Airport No. 1 The Airport Test Well was found to be satisfactory for a small domestic water supply to serve the Dubois Municipal Airport. The well utilizes a shallow aquifer of good quality water, produced between 55 and 64 feet below ground surface. The design rate for Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 1

7 Taylor Creek WESTVIEW DR W i n d R i v e r WARM SPRINGS RD AIRPORT RD HWY 26 LINCOLN ST Horse Creek Town of Dubois 5 HOUGH ST H O R S E C R E E K R D Wind River 9 Airport Test Well Test Well No. 1 Test Well No. 2 T42N T41N Well No. 11 R1 07W R1 07W Test Well No. 3 N 1 ST Miles ± Figure 1-1 Vicinity Map and Borehole Locations

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9 Airport No. 1 was determined to be 13 gpm. The conceptual design and cost estimate for well completion is provided in the Level II Study Report (Stetson Engineering, Inc. 2004) (L2SR), and additional details concerning the completion are provided in this report. A Form U. W. 5 has been processed for Airport No. 1 to produce a maximum rate of 15 gpm, and annual volume of 18 acre-feet (Appendix A). The permit rate of 15 gpm allows for some flexibility in the pump selection and the initial rate produced at startup, however, the long-term sustained rate from the well should not exceed 13 gpm. The beneficial use is designated as Miscellaneous, and was listed to include domestic, lawn watering, and aircraft maintenance. The Place of Use encompasses the entire airport property. Upon completion of Airport No. 1, the appropriate forms must be filed with the State Engineer s Office in order to secure the water right permit for the well. If the project is not completed by December 31, 2006, it will be necessary to file for an extension in order to preserve the priority date. The new airport water system will be restricted to the airport property, and consequently, should qualify as a non-community, transient system. This designation is optimal, as it allows for minimal operator time and water quality testing, which is appropriate for the type of water system being served Well No. 11 Well No. 11 was drilled at 16-inch diameter to 73 feet and screened from 51 feet to 67.5 feet (there is a 5-ft blank section below the screen). The maximum sustained capacity for the well is 1,200 gpm. The water quality is excellent, and basically the same as produced from existing Well No. 8. The two wells are within about 50 feet of one another in the same aquifer, however, Well No. 11 produces from a deeper interval. The Level II Study identified a minimum target rate of 550 gpm for Well No. 11 to meet future demand (assuming complete replacement of Well No. 8), and this may be the appropriate completion rate, although a final decision can be made during the design phase of the Level III project. It is recommended, however, that buried pipe and appurtenances be sized to accommodate the maximum rate of 1,200 gpm in order to facilitate future conversion. The conceptual design and cost estimate for well completion is provided in the Level II Study Report (Stetson Engineering, Inc. 2004). Additional details for completion are provided in this report. A Form U. W. 5 has been processed for Well No. 11 to produce a maximum rate of 1,200 gpm, and annual volume of 1936 acre-feet (Appendix A). This rate and volume will be matched to the completion equipment when the final completion forms are submitted to the State Engineer s Office. These submittals should occur immediately after completion of the well. An extension was filed for the completion date so if the well Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 2

10 is not completed by December 31, 2007, another extension will need to be filed with the State Engineer s Office. It is recommended that the Town pursue complete abandonment of the Well No. 8 facility once Well No. 11 is up and running. The work could be included in the Well No. 11 completion project. Abandonment is recommended because Well No. 8 is a poorly constructed facility, and the Town will continue to experience expenses for its operation. The Town should review the merits of this recommendation during the Level III design phase. If Well No. 8 is abandoned, the Town should petition the Board of the State Engineer s Office to move the Well No. 8 permit (U.W ) to Well No. 11. This petition should be made before the actual abandonment occurs, as the outcome of the petition is uncertain Pony Creek Road North Waterline Loop Investigation showed that a new pressure zone would have to be created to provide service to this area. The area is above the upper elevations that can be serviced by the existing Town water system. A layout of the model is shown on Figure 1-3. To service the area a pump station would need to be installed at the approximate location shown on the drawing. This would be installed at the approximate intersection of the extensions of Mountain View and Club House Drives. There is not currently a water line extended to this point, but it is recommended as a portion of Phase 7 of the distribution improvements in the L2SR. To reduce pump cycling, keep pressures more consistent, and provide fire protection to the area a water storage tank would have to be constructed. To provide adequate system pressures to the area shown, the working elevation of the tank would have to be approximately This elevation could be accomplished on the ridge between golf course area and the Tappan Creek drainage as shown on Figure 1-3. For creating a cost estimate it was decided to size a minimum tank large enough for a fire flow storage of 3,500 gpm for a duration of 3 hours (630,000) (this is the fire flow requirement determined for the high school in the L2SR). Actual sizing of the tank would need to be determined during a more detailed study of the possible needs in the area. During the development of this report it was decided by the Fremont County School District that the new high school will be built on the location of the existing school, not in the Tappan Creek area. The water line if installed to this area should eventually be looped all the way to the end of the existing line on Horse Creek Road. If the line was looped a pressure reducing valve would have to be installed at the approximate location shown. The pump Station was modeled on the west side of the loop because of the location and capacity of the new Water Supply Well No.11. Supply for demands and fire Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 3

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12 protection would be provided from this well instead of from the east tank which as discussed in the L2SR has inadequate fire storage. A tank on the North Side of town as indicated for this area would provide some additional supply to the downtown Dubois water system if the line was looped, but would not provide enough to make much difference to the fire protection in Town. During a fire flow event the east tank would still be drained in less then 2 hours causing pressures well below 20 psi in the Dubois Heights area. As discussed in the Section of the L2SR the best area for additional storage in Town is still near the existing East tank. 1.3 Contractor Fees and Work History The Dubois Test Well Drilling Project was bid as one project and awarded to the lowest responsible bidder, Andrew Well Drilling Services, Inc. of Idaho Falls, ID. The Engineer s Estimate for the project was $218,000. The project bid amount was $170,840, and the actual fees paid were $129,991. The lower amount actually paid was due to duplicating options in the bid (some of the items were not exercised in lieu of others), and actual quantities that were smaller than estimated quantities, resulting in a lower fee paid for the item. Bid tabulations and actual fees paid are provided in Appendix B. Contractor work commenced on June 6, 2005 and was fully completed November 4, A project history report is provided in Appendix B. 2 TEST WELL NOS. 1, 2 AND 3 Test Well Nos. 1, 2 and 3 were designated as Test Wells and permitted through the State Engineer s Office. Permit numbers UW163533, UW163534, and UW163535, were assigned respectively to the three test wells. Form U.W. 6 has subsequently been filed for each well documenting the abandoned condition. Test Well Nos. 1 and 2 (TW1 and TW2) penetrate the alluvial aquifer within a short distance of existing Well No. 8. The purpose of these test wells was to assess aquifer conditions and plan for a new production well at the site. Earlier work had found potentially that the aquifer was underutilized by Well No. 8. Due to a small casing size and shallow perforations, Well No. 8 could not be modified for much greater capacity than at present, if any. Figures 2-1 and 2-2 illustrate the geology and well constructions. Both sites were similar, although aquifer potential was much better at the location of TW1. At this location, much more gravel was encountered at depth than occurred in the TW2 borehole. It is important to note that at both sites approximately 18 feet of red silt was encountered at the surface. These materials provide excellent protection over the Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 4

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15 aquifer from surface contamination, and appear to have substantial lateral extent in the area. Because better conditions existed at TW1, it was pump tested and sampled for water quality. The results of pump testing indicated a new well installed at the site could yield about 700 gpm, and that a higher yield was possible. The results also concluded that a yield less than 550 gpm was unlikely. Water quality data confirmed that no unusual conditions would be encountered. The construction and testing of Well No. 11 was recommended based on this information and was subsequently authorized. A detailed report of the TW1 pumping test and recommendations is provided in Appendix C. Test Well No. 3 (TW3) was installed to evaluate the potential of an alluvial aquifer well on the K-8 School property north of downtown Dubois. A new well of good construction in this drainage was considered advantageous for source reliability, as it would be located outside of the Dubois commercial area and the area of possibly more intense development to the west of Town. Existing Well Nos. 6 and 7 are located in the Horse Creek drainage, and were thought to be developing groundwater from the alluvial aquifer in this area. As shown in Figure 2-3, the geology at the TW3 site consisted of approximately 54 feet of very coarse alluvial material, but is was dry. These materials consisted of sand to boulders and made for extremely difficult drilling. An eccentric tool with down-hole hammer action (ODEX) was used to successfully penetrate the materials. Below 54 feet, bedrock was encountered. The borehole was not terminated until a depth of 74 feet in order to fully verify the bedrock presence (initially the materials were moderately soft clay or claystone). The well was immediately abandoned because there was no alluvial aquifer at the site. The findings in borehole TW3 indicate that Well Nos. 6 and 7 are probably producing groundwater from a sandstone aquifer, rather than an alluvial aquifer (they could also be in different aquifer conditions). The rather sketchy information provided on the logs for these wells can now be better interpreted and also appears to support this finding. It appears most likely that both of these wells produce from the Nugget Sandstone, and that the bedrock encountered in TW3 was probably the lower part of the Gypsum Springs Formation. Alternatively, both wells could produce from sandstone beds in the Chugwater Formation, which would also be the uppermost bedrock encountered. 3 AIRPORT NO. 1 Airport No. 1 is a new well that will be used to serve the Dubois Municipal Airport. The well was drilled under a Test Well permit, and designated as the Airport Test Well 1. The 1 The well permitting process provides for a new well to be first drilled and tested as a Test Well, with no fee required for the permit. Once the well is shown to be useful, a new permit is issued to appropriate groundwater for beneficial use. The two permits use different well names, with the official name being designated on the second permit. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 5

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17 State Engineer s Office assigned this well permit number UW After drilling and testing was completed, a Form U.W. 6 was filed for this permit number. To use the well water beneficially, a Form U.W. 5 was subsequently filed designating the well name as Dubois Airport No. 1, and designating the well for Miscellaneous use. Airport No. 1 has been assigned permit number UW This permit allows for a maximum production rate of 15 gpm, and a maximum annual volume of 18 acre-feet. Permit copies for both the Airport Test Well and Airport No. 1 are provided in Appendix A. A Form U.W. 6 must be filed for Airport No. 1 upon the final completion of the well. An extension must be filed if the Form U. W. 6 is not filed prior to December 31, Geology and Well Construction Airport No. 1 is installed into a somewhat unique aquifer setting located within a terrace deposit of glacial till a few hundred feet above the Wind River channel. Well drilling at this location was met with substantial difficulty due to very hard conditions. The formation consists of sand up to possibly small boulders, with many cobbles on the order of four to six inch diameter. The cobbles include many basement rocks, consisting of gneiss and granite, and there are calcite cemented intervals possibly one to several feet in thickness. Under these conditions, casing refusal occurred above loose formation that collapsed inward. The occurrence of calcite cement within the glacial till is attributed to post depositional hot spring activity in the area. Possibly several thousand years ago, hot spring activity at the airport must have been significant, as the cliff south of the runway appears to be a large travertine deposit, most likely formed by precipitation from hot spring discharge (it is possible that others have mistakenly identified this cliff as Phosphoria Formation). Calcite cemented glacial till can also be observed at the foot of the hill below Airport No. 1 (on the Sedlacek property), which suggests that hot spring discharge may have permeated the land and then discharged at the base of the terrace. Calcite saturated pore waters resulted in cemented intervals, and possibly today, these cemented intervals are in part acting as boundaries to the aquifer. Figure 3-1 provides an as-built for Airport No. 1. The glacial till formation overlies mudstone of the Chugwater Formation at 64 feet below ground surface. Owing to difficulties in drilling, the 8-inch diameter casing could only be advanced to about 40 feet, and then the well was drilled open-hole into the mudstone to a total depth of 71 feet. Subsequently, a 6-inch diameter liner casing was advanced to total depth, and perforated from 61- to 63-feet. This casing was drilled and hammered through the open hole. Cement grout was emplaced into a 12-inch diameter borehole from surface to a depth of 18 feet. The grout provides a seal outside of the 8-inch diameter casing. The annular space between 6- and 8-inch casing is open. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 6

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19 Development by air-lift surging and pumping was conducted for 43.5 hours. Initially, the well produced essentially a low rate of red mud, which eventually gave way to a moderately clear discharge at a rate of about 1 to 2 gpm. Much of the flow from the aquifer was apparently held back by air, however, as pump testing (see below) found the well could probably produce up to 20 gpm at least for a short-term of several hours. The aquifer of Airport No. 1 is presumed to be unconfined. Static water level was 54.5 feet below ground surface, resulting in a saturated thickness of only 9.5 feet. A moderately large aquifer transmissivity enables a successful well installation in an otherwise marginal setting. The only other well known to be installed into the aquifer of Airport No. 1 is owned by Bill Sedlacek, and is located within 500 feet to the east. Based on the static water level and total depth of the Sedlacek well, in all likelihood these wells are within the same continuous aquifer zone. 3.2 Hydraulic Testing Airport No. 1 pump testing included step-rate and constant-rate tests. The well was equipped with a temporary pumping system provided by the project contractor. Test instruments were provided by the Engineer. Flow rate data were collected using a Controlotron 1010WP ultrasonic clamp on meter with a rated accuracy of 2% of reading. Pumping water level was measured using an Instrumentation Northwest PS9800 pressure transducer with a rated accuracy of 0.1% of rating (50 psig), and resolution of approximately ft. Data were collected at one and five minute intervals. Only the pumping well was monitored during testing. Monitoring of the Sedlacek well was considered, but due to access issues, a pressure transducer could not be directly installed in the well Step Rate Pumping Test The step rate test was run on June 30, 2005, and included six sequentially increasing pumping rates, ranging from 0.9 to 9.6 gpm. Figure 3-2 presents a hydrograph of pumping water level and discharge rate for the test. During the three hours of pumping for the step rate test, the maximum drawdown in the well was 1.27 feet. The maximum pumping rate that could be achieved in the well was limited by the size of pump. The low capacity pump was selected based in development work, which could only air-lift about 1 to 2 gpm from the well. As it turned out, the air-lift pumping during development was apparently blowing water back into the formation, and the actual capacity of the well is much higher. Figures 3-3 and 3-4 illustrate step rate test analysis plots. These results were used to select a pumping rate for the constant rate pumping test, and also to determine the turbulent head loss coefficient for the well. The turbulent head loss coefficient is the slope of the line shown in Figure 3-4, and is equal to ft/gpm 2. This parameter is used in determining the design pumping rate for the well (see below), and also may be used in comparison with future step rate pumping test data to assess well plugging. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 7

20 54.0 Depth to Water Discharge Rate Depth to Water (feet below ground) Discharge Rate (gpm) :00 PM 4:30 PM 5:00 PM 5:30 PM 6:00 PM 6:30 PM 7:00 PM 7:30 PM 8:00 PM Time, 6/30/05 Data collected from Airport No. 1. Figure 3-2 Airport No. 1 Step Rate Pumping Test Hydrograph 0

21 0.00 s1 = ft, Q1 = 0.9 gpm s2 = ft, Q2 = 3.1 gpm 0.25 s3 = ft, Q3 = 5.1 gpm 0.50 Drawdown (feet) 0.75 s4 = ft, Q4 = 7.1 gpm 1.00 s5 = 1.09 ft, Q5 = 9.1 gpm 1.25 s6 = 1.16 ft, Q6 = 9.6 gpm ,000 Time since pumping began (minutes) Data collected from Airport No.1. Listed drawdown for step is corrected for transient effects. Figure 3-3 Airport No. 1 Step Rate Pumping Test Semi-log Plot

22 Specific Drawdown (ft/gpm) s/q = 0.004Q R 2 = Data points determined from transient analysis of Airport No.1 step rate pumping test. Dotted line is linear regression fit to data points. Discharge Rate (gpm) Figure 3-4 Airport No. 1 Specific Drawdown Plot

23 3.2.2 Constant Rate Pumping Test Constant rate testing of Airport No. 1 occurred on July 1 2, The test consisted of a 24-hour pumping phase and recovery period. The recovery period was terminated after 3.5 hours when the residual drawdown in the well was 0.17 feet. The constant rate for the test was selected as 9 gpm, and the average rate achieved during the 24-hour pumping period was 9.1 gpm. The rate selected for the test was limited by the capacity of pumping equipment. A hydrograph for the constant rate test is shown on Figure 3-5. The test rate was held basically constant at 9.1 gpm except for a short period when a Rossum Sand Tester was attached to the discharge line. This instrument was immediately removed once the impacts to flow were observed. The test discharge was visually crystal clear, and there is no sand production expected for the completed facility. Total drawdown observed at the end of the pumping phase was 1.22 ft, resulting in a 24-hour specific capacity of 7.5 gpm/ft (specific capacity is equal to pumping rate divided by drawdown for a given pumping time). Several plots used to analyze the test are shown on Figures 3-6 through 3-8. The well response indicated on these plots includes a very short well storage period followed by a period of infinite aquifer flow. At the end of the pumping phase, the data appear to be responding to a recharge effect. In the geological setting of Airport No. 1 and given the occurrence of recharge late in the test, such an effect would normally be due to leakage from an adjoining aquifer zone. Aquifer transmissivity determined from the drawdown and recovery data was estimated as 2,190 and 1,710 ft 2 /d, respectively. These values are in good agreement with one another, and are indicative of a productive aquifer. The associated hydraulic conductivities were 230 and 180 ft/d, respectively. The drawdown data were also used to estimate a storativity of by conducting a Theis analysis on data corrected for the turbulent head loss component. 2 Worksheets for these analyses are provided in Appendix D Design Pumping Rate The Wyoming DEQ has established in the Chapter 12 Rules a method to determine the design rate of a water supply well. According to the rules, the design pumping rate is determined as 66% of the maximum rate of operation that can occur in a 24 hour period of continuous pumping 3, or stated alternatively, the well shall be tested at a rate equal to 1.5 times the design rate. 2 Each drawdown value was reduced by * Q 2, or 0.33 ft, where Q is the flow rate of the test (9.1 gpm). 3 Wyoming DEQ Chapter 12 Section 9(b)(ii)(A). Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 8

24 54.0 Sand content tester attached Depth to Water Discharge Rate Pre-test Static Water Level Depth to Water (feet below ground) Discharge Rate (gpm) :00 AM 2:00 PM 8:00 PM 2:00 AM 8:00 AM 2:00 PM Data collected from Airport No.1. Time, 7/1-7/2, 2005 Figure 3-5 Airport No. 1 Constant Rate Pumping Test Hydrograph 0.0 Western Groundwater Services

25 10.00 Drawdown Drawdown Derivative Drawdown and Drawdown Derivative [t(ds/dt)] (ft) Infinite aquifer flow Recharge effects Well storage period ,000 10,000 Time since pumping began (min) Data collected from Airport No. 1. Figure 3-6 Airport No. 1 Constant Rate Pumping Test Log-Log Plot

26 1.5 Straight line fit to data Possible recharge effects 1.0 Drawdown (ft) 0.5 Transmissivity Estimate = 2,190 ft 2 /d Aquifer Thickness = 9.5 ft Hydraulic Conductivity = 230 ft/d ,000 10,000 Data collected from Airport No. 1. Time since pumping began (min) Figure 3-7 Airport No. 1 Constant Rate Pumping Test Semi-Log Plot

27 Recovery Phase Drawdown (feet) Transmissivity Estimate = 1,710 ft 2 /d Aquifer Thickness = 9.5 ft Hydraulic Conductivity = 180 ft/d ,000 10,000 Data collected from Airport No. 1. Time since pumping began / Time since pumping stopped Figure 3-8 Airport No. 1 Constant Rate Pumping Test Horner Plot

28 Because of pump capacity limitations during testing of Airport No. 1, maximum drawdown was not achieved, and consequently the well was not pumped at its maximum rate. Given these conditions, the design rate was determined through calculation methods by applying a well hydraulic model to the test data. The model is used to calculate the maximum pumping rate that could occur in the well for a 24 hour period. The design rate is then determined as the calculated maximum rate divided by 1.5. The maximum pumping rate that can occur in a well is that rate that achieves maximum drawdown. The maximum pumping water level for Airport No. 1 is approximately 58 feet below ground surface. Given a static water level at 54.5 feet, there is a maximum of 3.5 feet of available drawdown. The maximum pumping water level of 58 ft allows for 1 ft of submergence over a pump intake set at 59 feet. The setting at 59 feet allows a 2 ft long motor to be entirely above the perforations, providing for adequate motor cooling. Figure 3-9 illustrates the results of fitting and applying the well hydraulic model to the Airport No. 1 test data. The model fit to test data is visually very good for early time, but deviates at later time when test data respond to a recharge effect. This condition indicates the model will overestimate drawdown in the well for long pumping times. The maximum rate determined for the well that would utilize the available drawdown of 3.5 feet in 24 hours of pumping was 20 gpm. The associated design rate is therefore gpm, or 20 gpm divided by 1.5. The model parameters in the fit to test data were as follows: transmissivity 2,190 ft 2 /d; storativity 0.006; well radius 0.33 ft; pumping rate 9.1 gpm; skin factor -1; and turbulent head loss coefficient ft/gpm 2. Of these parameters, only the skin factor is adjusted during model fitting. The negative skin factor indicates that development has enhanced permeability at the well aquifer interface, which is reasonable given the substantial length of development that was performed. Model worksheets are provided in Appendix D. 3.3 Water Quality Two water quality samples were collected from Airport No. 1. A midpoint sample was collected during the step rate pumping test on June 30, 2005, and assigned sample identification ATW MC. This sample was analyzed for an abbreviated list of parameters. An endpoint sample was then collected after 5.75 hours of pumping during the constant rate test on July 1, This sample was assigned identification ATW MC. The endpoint sample was collected early in order to meet holding time requirements (due to the 4 th of July). The first sample was collected after pumping 995 gallons from the well, or 71 casing volumes. The second sample was collected after pumping 2,700 gallons from the well. The analytical results from the laboratory are provided in Appendix E. The water was found to be in compliance with regulated parameters, and therefore should not require treatment (assuming the sampling results prevail into the future). It is Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 9

29 Time since pumping began (days) Model Test Data Prediction Predicted drawdown at gpm 2 Drawdown (feet) 1.5 Model overestimates drawdown at later time due to recharge affect. 1 Model fit to test data (9.1 gpm) ,200 1,500 Prediction curve uses upper time axis in units of days. Model fit to test data uses lower time axis in units of minutes. Time since pumping began (minutes) Figure 3-9 Airport No. 1 Design Rate Analysis

30 also noteworthy that if the system is developed as a non-community transient system, most of the regulated parameters do not apply, except for nitrogen and coliform. Comments related to the water analysis are as follows: There was little if any difference in parameter values when the midpoint sample was compared to the endpoint sample. Coliform bacteria were absent in the endpoint sample and the water was designated as safe. A coliform detection occurred in the midpoint sample, but E. coli was found to be absent. This result probably reflected contamination of the well by the pumping equipment, which subsequently cleaned up. The well was disinfected upon removal of the equipment. There were non-pathogenic iron-related bacteria, and heterotrophic plate count bacteria detected in the samples. If the well were to be found plugged at some future time, it is possible these organisms have caused or contributed to the condition. The occurrence of nitrate at 1.1 mg/l as nitrogen is substantially below the MCL of 10 mg/l. This level probably represents a normal background level. The water is very hard and may encrust fixtures, particularly hot water heaters. The Langlier index of 0.85 indicates slightly encrusting conditions. High alkalinity in the water will likely result in carbon dioxide degassing when it is exposed to atmosphere. Total dissolved solids at 746 mg/l is moderately high, and exceeds the secondary standard of 500 mg/l (non-enforceable). Arsenic occurred at mg/l, which is only slightly below the MCL of 0.01 mg/l. As noted above, arsenic is not regulated in a non-community transient water system. Iron and manganese, although detected, were below the secondary standards. No deposition is expected due to these constituents, and treatment is not required. Radon concentration in water at 941 pci/l exceeds the potential MCL of 300 pci/l, but is significantly below the alternative MCL of 4,000 pci/l. Radon is not presently regulated, and probably will not be regulated in non-community transient water systems. Toluene was detected in the sample at mg/l, and has an MCL of 10 mg/l. It is possible this constituent occurred as a sample contaminant and was not actually in the groundwater. The detected concentration was substantially Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 10

31 below the regulated MCL. Toluene also is not regulated in a non-community transient water system. Ion data indicate pore water equilibrium (or slight oversaturation) with respect to calcite and quartz. This finding supports the occurrence of carbonate cement, and the dominantly silicate rock mineralogy. 3.4 Completion Recommendations A conceptual design for the Airport No. 1 completion is provided in the Level II Study Report (Stetson Engineering 2006). Additional recommendations based on the construction and testing of the well are provided below. The well pump should not exceed 13 gpm. A 10 gpm pump may be a better match to the system and will be less stressful on the aquifer. The pump can be hung on a pitless adapter installed into the 8-inch diameter casing. It will be necessary to cut-off the 6-inch diameter casing sufficiently below the point of attachment (~ 2 ft). The bottom of the pump motor should be at a depth of 61 feet below ground surface. This depth coincides with the top of casing perforations. A 1-inch diameter PVC pipe should be installed alongside the pump column for the purpose of water level measurements. This pipe should begin immediately below the well cap, and should extend to the top of the pump. The bottom of the pipe should be capped, and the pipe should be perforated over the lowest 10 feet. Perforations of 3/8 inch diameter installed at two or three per foot are adequate to allow for water level equilibration inside and outside the tube. 4 WELL NO. 11 Well No. 11 is a new municipal production well that will serve the Town of Dubois public water system. This well was drilled as Well No. 11 Test Well and designated as a Test Well. It was assigned permit number UW A Form U. W. 6 was filed for this permit number after construction and testing of the well. A Form U. W. 5 was filed for Well No. 11 to appropriate groundwater. Well No. 11 has been assigned permit number UW The permit rate is 1,200 gpm, and the annual volume is 1194 acre-feet. A Form U. W. 6 or a request for extension of this permit number must be filed on or before December 31, If Well No. 8 is abandoned, the Town should petition the SEO Board to move the appropriation pertaining to Well No. 8 over to Well No. 11. This petition should be made and approved before abandonment of Well No. 8. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 11

32 4.1 Geology and Well Construction Well No. 11 was drilled by the cable tool method to a total depth of 73.5 feet (Bucyrus Erie 36L). It was located about 6 feet north of Test Well TW1 discussed above. Figure 4-1 provides an as-built construction and geological log for the well. The geology at the site consists of reddish brown silt to a depth of 18 feet; sand and gravel with clay to 32.5 feet; and then good aquifer material to 69.5 feet where bedrock is encountered. There were differences in the samples from Well No. 11 and TW1, but these are likely attributed to sampling and drilling method. As noted earlier, the silt cap over the aquifer provides a natural barrier to the direct migration of surface contaminants to the well. The lateral extent of this stratum is not fully defined, but it appears to be extensive at least to the west of Dubois. It likely formed due to the erosion of Wind River Formation rocks to the north, and the subsequent deposition of these materials in the Wind River valley. It probably exists in most of the valley where it is bordered by the Wind River Formation. It would be thickest near to the outcrop area and then thin towards the river channel. The aquifer material, which is considered to extend from 32.5 to 69.5 feet, is clean, loose alluvium consisting of mostly sand and gravel, with possibly a few percent silt. These materials are interpreted as glacial outwash deposits formed during the Pinedale glacial episode 16,000 to 23,000 years before present. The terminal moraine for Pinedale glaciers was just west of Stoney Point. Deposition onto the glacial outwash plane occurred from this location and to the east. Samples that were analyzed for gradation analysis are listed on Figure 4-1, and detailed results are provided in Appendix F. Eight of 13 samples collected through the screened interval included more than 20% gravel. One sample had 57% gravel; a few others had in excess of 40% gravel. The material was non-uniform, reflecting poor sorting and a diversity of grain sizes present. Information on grain mineralogy is provided below in Section 5. The well screen was manufactured by Alloy Machine Works, Inc. and built from 304 stainless steel. Details of the screen construction are provided in Appendix F. A single slot size of inches was selected based on the sample gradation analyses. This selection appears to have been slightly small although it exceeds the 70% passing size of several samples. The screen includes a 5 ft long stainless steel pipe at the base, which provides a sump. This blank interval allows for an 8-inch diameter submersible pump to be installed below the screen, surrounded by a 10-inch diameter flow sleeve, if at some future time this configuration is desired in order to maximize available drawdown in the well. Surge block and sand pump development was completed through the screened interval for 46 hours. The screen was worked upwards and downwards several times during Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 12

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34 this effort. A total of 29 cubic feet of sand was developed from the well, or 1.75 cubic feet for each foot of exposed screen (total of 16.5 feet exposed). 4.2 Hydraulic Testing Hydraulic testing of Well No. 11 included step-rate and constant-rate pumping tests. A temporary pumping system was installed for testing by the project contractor. Data collection was conducted by the Engineer using computerized and manual instruments. Flow rate, water level, and sand content was measured in Well No. 11. Water level data were also collected from Test Well Nos. 1 and 2. Flow metering used a Controlotron 1010WP ultrasonic clamp on meter accurate to 2% of reading. Water level data were collected using Instrumentation Northwest, Inc. PS9000 and PS9800 pressure transducers. Sand content was measured using a Rossum Sand Tester. Flow and water level data were recorded by computerized logging equipment at frequencies of 1 and 5 minutes throughout the duration of testing Step Rate Pumping Test A hydrograph plot for the step rate pumping test in Well No. 11 is shown on Figure 4-2. Eight pumping steps, each one hour in duration, were run for the test. The starting rate was 201 gpm, and the maximum rate in the last step was 1,322 gpm. The maximum drawdown occurring at the end of pumping was feet. Figures 4-3 and 4-4 illustrate plots and values used to analyze the step rate pumping test. The points shown on Figure 4-4 are derived from the drawdown and flow rate values shown on Figure 4-3. The slope of the regression line shown on Figure 4-4 is the turbulent head loss parameter, which is equal to ft/gpm 2. This low value is indicative of a properly designed and developed well (Todd 1980) Constant Rate Pumping Test The constant rate test in Well No. 11 included seven days of pumping followed by seven days of recovery. A hydrograph for the data collected in Well No. 11 is presented on Figure 4-5. The average discharge rate for the test was 1,013 gpm. The maximum drawdown occurring at the time a power failure occurred was ft. The specific capacity at this time, which corresponds to 144 hours of pumping, was 73.6 gpm/ft. The alluvial aquifer is confined by the overlying red silt over most of the area responding to the pumping test. Given the red silt extends to a depth of 18 feet, during the pumping phase of the test, water level was pulled below the red silt only at Well No. 11, whereas water levels at Test Wells TW1 and TW2 remained up in the silt, indicating confined aquifer conditions. It is also noteworthy that the clayey sand and gravel from 18 to 32.5 feet also could be a confining bed above the aquifer. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 13

35 1,400 Discharge Rate 0 Depth to Water 1,300 1,200 Discharge Rate (gpm) 1,100 1, Depth to W a ter (feet below ground surface) :00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM September 27, 2005 Data collected from Well No. 11. Figure 4-2 Well No. 11 Step Rate Test Hydrograph

36 s1 = 1.56 ft, Q1 = 201 gpm s2 = 2.64 ft, Q2 = 329 gpm s3 = 3.82 ft, Q3 = 450 gpm 5.0 s4 = 5.23 ft, Q4 = 574 gpm s5 = 6.83 ft, Q5 = 703 gpm Drawdown (feet) s6 = 8.66 ft, Q5 = 826 gpm s7 = ft, Q7 = 963 gpm s8 = ft, Q8 = 1322 gpm Data collected from Well No. 11. Listed drawdown for step is corrected for transient effects. Time since pumping began (min) Figure 4-3 Well No. 11 Step Rate Pumping Semi-log Plot

37 ) S pecific D rawd o wn (ft/gpm s/q = 5E-06Q R 2 = Discharge Rate (gpm) Figure 4-4 Well No. 11 Specific Drawdown Plot

38 0 Depth to Water 1,200 Power outage Discharge Rate 1,100 5 Pump off 1, Depth to Water (ft bgs) Discharge Rate (gpm) /28/2005 9/30/ /2/ /4/ /6/ /8/ /10/ /12/ Pre-test static water level at Well No. 11 = ft bgs. Figure 4-5 Well No. 11 Constant Rate Test Hydrograph

39 Constant rate test analysis plots are shown on Figures 4-6 through 4-8, and are also included in Appendix G. These plots illustrate several aspects of the aquifer from which Well No. 11 produces groundwater. The aquifer is heterogeneous resulting in changes in transmissivity with location. This finding is not particularly unusual and reflects variation in the transmissivity of alluvium from one location to another, most likely due to deposition. The scale of this heterogeneity is on the order of a few hundred feet. It is exhibited by the drawdown data collected in Test Well TW2 versus those collected in Test Well TW1 and Well No. 11 (see Figures 4-6 and 4-7). The aquifer is influenced by a larger scale feature that limits flow, and which is much more distant, perhaps more than 10,000 feet effectively from the well location. This flow limiting feature is probably related to the boundary between alluvium and bedrock at the valley margins, although it is more complicated than a single linear boundary. The increase in drawdown that occurs after about 1,000 minutes of pumping time illustrates this feature. It is shown very well by the data collected in Test Well TW2 and Well No. 11. Transmissivity of the aquifer at the location of Well No. 11 is estimated as 60,200 ft 2 /d, which is indicative of a high production alluvial aquifer. The estimated storativity is 10-4, which is a confined aquifer value Design Pumping Rate Determination of the design rate for Well No. 11 was made based on a well hydraulic model fit to the constant rate test data. The model fit to test data is shown on Figure 4 9. The model used represents the aquifer as inner and outer cylinders with differing transmissivity and storativity. In this application of the model, the storativities were assumed equal in the two zones. The model fit is visually very close to the test data. Worksheets for the model are provided in Appendix G. Design rate estimates were made based on the available drawdown in Well No. 11. Available drawdown was determined as 22 feet assuming a pump location above the screen (see Figure 4-10). It is feasible to install a pump below the screen, which would result in significantly greater capacity potential for the well. In the first application of the model, the DEQ design rate was calculated based on the criteria of the Chapter 12 Rules. A rate of 1,525 gpm was determined to result in full drawdown in the well after 24 hours of pumping. The associated design rate is 1,017 gpm, essentially the test rate (1525/1.5 = 1017). A more technical application of the model to determine design rate specifies a duration of pumping over which the available drawdown is fully used. In this application, a time period of 365 days was used, which is typical for municipal wells in an alluvial aquifer. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 14

40 20 Well No. 11 Test Well TW1 Test Well TW2 Boundary Effect 15 3X Transmissivity = 60,200 ft 2 /d Drawdown (ft) 10 Transmissivity = 67,800 ft 2 /d Probable sensor position movement 5 Boundary Effect 4X Transmissivity = 87,200 ft 2 /d, Storativity = E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 Time since pumping began (min) Figure 4-6 Well No. 11 Constant Rate Test Semi-Log Plot

41 15 Well No. 11 Test Well TW1 Test Well TW2 10 Drawdown (ft) 5 The offset of Well 11 and TW1 data is mostly attributed to well losses, and to a much lesser degree heterogeneity. In a homogeneous aquifer, the data for TW1 and TW2 should fall on a single straight line. The offset reflects aquifer heterogeneity. 0 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 Time since pumping began / radial distance 2 (min/ft 2 ) Figure 4-7 Well No. 11 Constant Rate Test Normalized Semi-Log Plot

42 10.00 Well No. 11 Test Well TW2, r=151 ft Drawdown Derivative (t*ds/dt, ft) Infinite Aquifer Radial Flow Aquifer heterogeneity effect Log differential interval = 0.5 Time since pumping began (min) Figure 4-8 Well No. 11 Constant Rate Test Derivative Plot

43 20 15 Model Parameters T 60,200 ft 2 /d T2 17,200 ft 2 /d S S r ft L 20,000 ft skin 1.9 C 5E-06 ft/gpm 2 Q 1,013 gpm Model Test Data Drawdown (ft) ,000 10, ,000 Data collected from Well No. 11. Model based on heterogeneous aquifer with radial discontinuity. Time since pumping began (min) Figure 4-9 Well No. 11 Constant Rate Test Model Fit

44 Available Drawdown Static Water Level Bottom pump Motor Pump intake Pump submergence Net available drawdown 14 ft 51 ft 46 ft 10 ft 22 ft Drawdown Well Efficiency 100% 90% 80% 30 Values calculated for 365 days of continuous pump operation 70% Drawdown at 365 days (ft) Available Drawdown = 22 ft 60% 50% 40% 30% Well Efficiency (% ) 10 20% 5 Design Rate = 1,200 gpm 10% 0 0% Calculations based on radial discontinuity model fit to Well No. 11 constant rate test data. Available drawdown based on 100 hp submersible pump. Discharge Rate (gpm) Figure 4-10 Well No. 11 Design Rate Analysis

45 By this approach the design rate was determined as 1,200 gpm, as shown on Figure Well efficiency was also estimated based on the well hydraulic model. In this application, the model is run with and without head loss factors. The results are shown on Figure 4-10, and vary with pumping rate. The maximum efficiency of 63% occurs at a pumping rate of 600 gpm. The efficiency at 1,200 gpm is 58%. These values are low for a large diameter alluvial aquifer well completion, as typical efficiencies range from 75% to 100%. It is questionable as to whether or not additional development could improve well efficiency, as the screen slot size is probably impeding the transmission of energy to the formation. A larger rig and more aggressive tools would be required. Given this interpretation, it is noteworthy that the slot size selected for the screen actually is larger over some of the sample intervals than would be selected by application of design standards (e.g., ANSI/AWWA A-100, Driscoll 1986). This finding suggests the design standards are overly conservative, and while protective of sand production from the well, they are not likely to maximize well efficiency. 4.3 Water Quality Two water samples were collected from Well No. 11 during hydraulic testing. A midpoint sample designated as Well MC was collected midway through the step rate pumping test. An endpoint sample designated as Well MC was collected at the end of the constant rate pumping period. Water quality reports for both samples are provided in Appendix H. The midpoint and endpoint samples compare closely to one another, with only slight differences in matched parameter values. Figures 4-11 and 4-12 show field data collected for water conductivity, ph, and temperature during the pumping phase of the constant rate test. These parameters were generally stable throughout the pumping period. Sand content was measured during the constant rate pumping test on September 28, A Rossum Sand Tester (RST) was attached to the discharge from the start of pumping at 11:30 AM to 6:00 PM on the same day. There was no detectable sand measured in the 195 gallons of discharge passed through the RST over the testing period. The water produced from Well No. 11 was found to be compliant with regulatory and aesthetic standards. There are no treatment requirements, other than disinfection, that may apply to the use of the water in a community public water system. The water was found to be free of coliform bacteria and designated as safe. Overall, the water produced from Well No. 11 would likely qualify as among the best quality that is available in the state of Wyoming. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 15

46 Specific Conductance ph /cm) Specific Conductance (us ph (standard units) /28 9/29 9/30 10/1 10/2 10/3 10/4 10/5 10/6 4 Data collected from Well No. 11. Figure 4-11 Well No. 11 Field Water Quality Parameters

47 ) Temperature (C ) Temperature (F /28 9/29 9/30 10/1 10/2 10/3 10/4 10/5 10/6 30 Data collected from Well No. 11. Figure 4-12 Well No. 11 Water Temperature

48 The only minor exceptions that can be identified with respect to water quality include the water hardness and radon concentration. Water hardness is given a Hard designation, with a concentration of 248 mg/l as calcium carbonate. Encrustation, particularly with respect to hot water heaters, is a likely possibility. The radon concentration was 484 pci/l. Radon is not yet regulated, but is expected to be in the near future. The MCL for radon in draft regulations was identified as 300 pci/l, with an alternate MCL of 4,000 pci/l. Because EPA has primacy in Wyoming, there is some potential that the lower limit could apply unless the state of Wyoming implements a statewide multi-media radon mitigation plan. Alternatively, the Town could prepare and implement a multi-media radon mitigation plan and also fall under the higher limit. Rock mineralogy in equilibrium with groundwater was evaluated by geochemical analysis using the USGS PHREEQC computer program. The results of this analysis indicate mineral-water equilibrium with plagioclase feldspar, quartz (including chalcedony), calcite, and dolomite. Additional information on formation mineralogy is provided in Section Completion Recommendations Once Well No. 11 is up and running, it is recommended that the Town pursue complete abandonment of the Well No. 8 facility. Abandonment is recommended because Well No. 8 is a poorly constructed facility, and the Town will continue to experience expenses for its operation. The Town should review the merits of this recommendation during the Level III design phase Well Completion It is recommended that the well be completed using a pitless adapter and submersible pump. A pitless style completion and submersible pump are recommended to provide for easier future access to the well. The pump should provide a minimum rate of 550 gpm as determined in the L2SR, and because of the limitations of the existing water distribution and transmission system should not exceed a design flow of about 780 gpm. The recommended design rate at this time is 600 gpm which is also the estimated rate to provide maximum efficiency from the well. Based on the population projections and water use rates discussed in the L2SR, the rate of 600 gpm should enable the Town to meet estimated demands until approximately year If the Town follows the Water Supply Capacity alternatives recommended in Section 3 of the L2SR, the next supply improvements done would be to replace the pump in Well No.10 and increase the size of the pump house piping to allow for the additional capacity. This should allow the system to meet the demands to the end of the project planning period of If the Town sees sudden unanticipated growth to the west prior to the improvements to well No.10, the Town may want to look at increasing the capacity of well No.11 first. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 16

49 Because the well has a potential capacity of 1,200 gpm it is recommended that all appurtenances and piping be sized to accommodate this maximum rate. Specific recommendations for completion of the well are as follows: The pitless should be sized to allow for the future increase in pump and pump column size. A 1-inch diameter PVC pipe should be installed alongside the pump column for the purpose of water level measurements. This pipe should begin immediately below the well cap, and should extend to the top of the pump. The bottom of the pipe should be capped, and the pipe should be perforated over the lowest 10 feet. Perforations of 3/8 inch diameter installed at two or three per foot are adequate to allow for water level equilibration inside and outside the tube. The piping between the pitless and control building should be ten inch (10 ) in diameter Control and Treatment Building It is recommended that a new building be constructed for the control and treatment of Well No.11. The piping in and under the new building should be ten inch in size to accommodate for the 1,200 gpm maximum potential flow rate of the well. The existing building is not large enough to accommodate the piping requirements. The constructing of a new building would also allow well No.8 to remain on line during the completion and connection of well No.11. The building must be sized to meet the requirements for piping, pump control, and water treatment. The location of the building must be laid out so as not to block easy future access to the well head. Final determination of the building location will partially depend on the determination of abandoning well No Connection to the Existing System The existing well No.8 is connected directly to the east tank by a 6 PVC water line. This line does not have the capacity to provide for the new well. Assuming a max velocity in the line of 5 ft/sec, the maximum capacity of the 6 line is about 440 gpm. Alternatives were investigated to determine what would be the best option to connect the new well to the system. Two primary connection configurations were investigated. The first was to connect directly to the system near Well No.11, and the second was the replacement of the existing 6 tank supply line with a larger diameter (8 PVC) line. After looking at model responses in the existing system based on these changes, it is recommended that the new well be connected directly to the existing water system piping along the street to the east (alley-way referred to as Taylor Creek Road East). The line in this street is six inch and should be replaced with 10 PVC from the connection point of the new line from the building south to the tee of the existing 8 line. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 17

50 The new line from the building should be 10 PVC. See figure It was determined that by tying directly into the system and making the above modifications the model showed better overall system responses in regards to pressures and capacities in both the west and east areas of Town. The improved responses included increased fire flow capacity to the area surrounding the golf course and providing better flow between the east and west portions of the water system. Assuming the West Tank is low during a peak day demand period,having the well tied directly into the system would still provide flows to east while the tank is filling. Whereas the modeling shows that if the well is tied into the tank only, demands in the area would need to be supplemented from the eastern portion of the system. We do not feel this would be fully utilizing the capacity of the well. Tying directly into the system would also be the least work alternative for the project. Conceptual Construction Cost estimates for both alternatives are provided in Tables 4-1 and 4-2 and discussed in following sections. If it is determined by the Town to keep Well No.8 on line as a back up it would still be connected directly to the tank and would require no changes. One concern to investigate further during final design of the connection is the concern of the new Groundwater rule. We have discussed this with Jeff Hermansky and James Brough with the Water Quality Division of the Wyoming Department of Environmental Quality in Lander Wyoming. After discussions with Jeff and James it is our understanding that the groundwater rule does not automatically require disinfection and contact time. If the well is not under the influence of surface water, is properly constructed and sealed, and you sample and do not have a fecal indicator in the raw supply, then the disinfection rule does not apply. The new rule does not state Though Shall Disinfect. The new well is properly constructed and sealed, not under the influence of surface water, and did not show any contamination. At this time we do not believe this to be an issue with the well. If the well were ever sampled and showed a fecal indicator, then the Town would need to comply with the treatment technique of the rule, which would require 4-log inactivation of viruses, or about a CT value of 6-8 minmg/l SCADA Control The new well should be connected to the existing Town SCADA System and controlled by Tank levels from the West Tank. It will depend on the whether or not well No.8 is abandoned whether new equipment will be required or if the existing system from well No.8 can be used. If new equipment is used it must be designed to meet the requirements of the existing system. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 18

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52 4.4.5 Cost Estimates The following table provides the cost estimate assuming the new Well No.11 is connected directly to the existing system and approximately 255 lf of existing 6 PVC is replaced with 10 PVC water main. TABLE 4-1 Well Completion and Connection to Existing Water System Cost Estimate UNIT TOTAL NO. ITEM UNIT QUANTITY PRICE PRICE 1 Well Modifications (Pitless, Pump, Wire) LS 1 $ 45,000 $ 45,000 2 Other Mechanical LS 1 $ 19,500 $ 19,500 3 Electrical LS 1 $ 13,000 $ 13,000 4 Controls LS 1 $ 13,000 $ 13,000 5 SCADA Control Terminal LS 1 $ 10,000 $ 10,000 6 Chlorine disinfection LS 1 $ 5,000 $ 5,000 7 Building LS 1 $ 19,500 $ 19, PVC Transmission pipeline LF 320 $ 45 $ 14,400 9 Connect to existing EA 1 $ 2000 $ Electrical service to well LS 1 $ 12,000 $ 12,000 Construction Subtotal = $ 155,500 Construction Engineering (10%) = $ 15,550 Construction Subtotal = $ 171,050 Contingencies (15%) = $ 25,658 Total Construction Costs = $ 196,708 NON CONSTRUCTION COSTS 11 Final Designs and Specification $ 20, Permitting $ 500 Total Non-Construction Costs = $ 20,500 TOTAL ESTIMATED PROJECT COST = $ 217,208 USE $217, Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 19

53 The following table provides the cost estimate assuming the system is connected directly to the existing tank supply line and the existing 6 PVC is replaced with 8 PVC water main. TABLE 4-2 Well Completion and New Tank Transmission Line Cost Estimate UNIT TOTAL NO. ITEM UNIT QUANTITY PRICE PRICE 1 Well Modifications (Pitless, Pump, Wire) LS 1 $ 45,000 $ 45,000 2 Other Mechanical LS 1 $ 19,500 $ 19,500 3 Electrical LS 1 $ 13,000 $ 13,000 4 Controls LS 1 $ 13,000 $ 13,000 5 SCADA Control Terminal LS 1 $ 10,000 $ 10,000 6 Chlorine disinfection LS 1 $ 5,000 $ 5,000 7 Building LS 1 $ 19,500 $ 19,500 8 Replace 6" line with 8" PVC Water Line LF 2400 $ 50 $ 120,000 9 Connect to existing EA 1 $ 2,500 $ 2, Electrical service to well LS 1 $ 12,000 $ 12,000 Construction Subtotal = $ 259,500 Construction Engineering (10%) = $ 25,950 Construction Subtotal = $ 285,450 Contingencies (15%) = $ 42,818 Total Construction Costs = $ 328,268 NON CONSTRUCTION COSTS 11 Final Designs and Specification $ 30, Permitting $ 1,500 Total Non-Construction Costs = $ 31,500 TOTAL ESTIMATED PROJECT COST = $ 359,768 USE $360, Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 20

54 5 PHOTO PLATES This section provides a series of photos used to illustrate project work and geological conditions. Each photo is accompanied by a description pertaining to its details. Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 21

55 Test Well Drilling Test Well Nos. 1 through 3 and the Airport Test Well were drilled using the air-rotary method. Air-lift pumping during drilling provides a means to generally assess water production potential of the aquifer. Glacial Outwash Plane The drill rig mast on Well No. 11 can be spotted immediately south of the road near the center of the picture. The glacial outwash plane, which is covered by red silt deposits can be seen in the distance. Well No. 11 Drilling Cable tool drilling was selected for Well No. 11 to take advantage of the spudding action during well development. The method also is capable of drilling large diameter boreholes effectively, and the short depth of the well reduced the importance of penetration rate. A large bailer is shown ready to go down the hole to bail drilling cuttings. Photo Plate 1

56 Well No. 11 Screen The center of the photo shows the stainless steel well screen installed into Well No. 11. The screened interval of the well is from 51 to 67.5 feet. The screen provides a large open area for water entry. The stainless steel construction maximizes screen longevity. The well life of this construction could exceed 100 years. Well No. 11 Pump Testing The large well casing of Well No. 11 can be seen in the lower right of the photo. From this point, discharge piping runs horizontally across the photo. A flow meter is mounted on the horizontal pipe, and pressure sensors are installed down Well No. 11, and Test Well No. 1 (bottom center). The well was tested up to 1,320 gpm during the step rate test, and at 1,013 gpm during the constant rate test. Pump Testing Equipment The upper left photo shows the transducers of the ultra-sonic flow meter clamped onto the discharge pipe. This meter allows for flow measurement without any moving parts or contact with the discharge water. The lower right photo shows the Rossum Sand Tester used to measure sand content in well discharge. This device is the most accurate practical method for sand measurement. It works as a miniature centrifugal sand separator. Photo Plate 2

57 Test Well No. 1, Sand at 40 ft Sand-sized grains obtained from borehole sample are shown at 26X magnification. Large grain in center is oolitic limestone, probably from Paleozoic rocks in the area. The dark green grain to right is pyroxene. The large grain in the lower right is volcanic andesite. Test Well No. 2, Sand at 60 ft Sand-sized grains obtained from borehole sample are shown at 16X magnification. Clean sand is subangular to subrounded, and includes a variety of mineral types. Light gray to clear grains are quartz and feldspar; darker grains are a mixture of pyroxene and andesite. Grain size is 0.2 to 2 mm. Test Well No. 1 Sand at 40 ft in Thin Section Sand-sized grains obtained from borehole sample are shown at 40X magnification as viewed in crossedpolarized light through a petrographic microscope. Tan to brown grains are carbonates. Colorful blue grain on right margin is clinopyroxene (as is yellow grain along bottom). White and gray grains are feldspar and quartz. Grains with multiple small minerals are andesite. Photo Plate 3

58 Well No. 11 Thin Section, 63 ft Sand-sized grains are shown in plane polarized light, viewed at 40X magnification. The dark grains are primarily andesite derived from volcanic rock, consisting of plagioclase feldspar, pyroxene (CPX and OPX), and volcanic glass. The volcanic grains dominated the sand observed in borehole samples from all of the borings installed for the project. The large grain in the lower center of the photo is plagioclase feldspar. Well No. 11 Thin Section, 63 ft The above photo is shown in crossed polarized light. With close inspection, zoning can be observed in the large plagioclase grain in the lower center of the photo. Colored pyroxene grains can also be seen within the andesite grains. Airport No. 1 Thin Section, 60 ft Plane polarized light view of andesite grain in borehole sample. Blocky white grains are all plagioclase feldspar, and likely high in calcium. Small black grains are magnetite with some hematite rims. Grainy matrix material is microcrystalline groundmass and volcanic glass. The overall light color classifies this grain as andesite, along with the absence of abundant pyroxene. The multi-mineral sand grains occurring in the aquifers will tend to increase the natural purification of pore waters. Photo Plate 4

59 Terrace Deposit of Glacial Till below Dubois Overlook Glacial till shown in hillside of terrace deposit. Larger rocks are cobbles of approximately 4 to 6 inch diameter. These deposits were formed in relation to the Bull Lake glacial episode. Cemented Glacial Till near Dubois Airport Cemented glacial till is shown in roadcut below Dubois Airport. Hammer is 1 ft in length. Note uncemented loose bed occurring below larger cemented interval. This loose bed may have been deposited from a river flowing over the till, and then later buried by till. Travertine Cliff at Dubois Airport Outcrop south of Dubois Airport consists of limestone most likely deposited from hot spring discharge. These rocks suggest a large historical hot spring at this location. Cemented till in the Airport No. 1 aquifer may have formed in relation to hot spring discharges. Photo Plate 5

60 6 PONY CREEK RD. NORTH WATER LINE LOOP The Town of Dubois requested that some preliminary investigation be done to look at the feasibility of providing water supply service to the Pony Creek Road area north of Town. Pony Creek Road connects to Horse Creek Road about 0.7 miles North of Dubois. The area of interest follows Pony Creek Road north-westerly for approximately 1.25 miles. The area is along Tappan Creek and has been considered as a possible site for the new High School and possible Town expansion. Figure 6-1 provides a map of the area of interest Cost Estimates The area was investigated by adding a new water line to the existing water model created in the L2SR. The line was added from the west side of the Town System. The line was started from the west side of the loop because of the location and capacity of the new Water Supply Well No.11. This well as discussed in this report has a potential capacity of 1,200 gpm. Supply for demands and fire protection in the area would be provided from this well instead of from eastern portion of the system (the east tank, well 10, and well 6), which as discussed in the L2SR already has inadequate fire storage. The water line if installed to this area should be designed to eventually be looped all the way to the end of the existing line on Horse Creek Road. A summary of the data added to the existing model is included in Appendix I. Investigation showed that a new pressure zone would have to be created to provide service to this area. The area is above the upper elevations that can be serviced by the existing Town water system. A layout of the model is shown on Figure 6-2. To service the area a pump station would need to be installed at the approximate location shown on the drawing. This would be installed at the approximate intersection of the extensions of Mountain View and Club House Drives. There is not currently a water line extended to this point, but it is recommended as a portion of Phase 7 of the distribution improvements in the L2SR. If the line was looped a pressure reducing valve would have to be installed at the approximate location shown to match the existing system pressures. To reduce pump cycling, keep pressures more consistent, and provide fire protection to the area, a storage reservoir should be constructed. To provide adequate system pressures to the area shown, the working elevation of the reservoir would have to be approximately This elevation could be accomplished on the ridge between golf course area and Pony Creek Road as shown on Figure 6-2. The model was investigated using the minimum line sizes required to meet the minimum WDEQ Chapter 12 design standards in regards to pressures during normal system and fire flow demands. Because we were looking at the potential for a new school in the area we modeled the system using fire flow demands of 3,500 gpm for a duration of 3 hours. For creating a feasibility cost estimate (Table 6-1) it was decided to size a minimum tank large enough for a fire flow storage of 3,500 gpm for a duration of 3 hours (630,000) (this is the fire flow requirement determined for the high school in the L2SR). Actual sizing of the reservoir and transmission lines would need to be determined during Stetson Engineering, Inc. Dubois Test Well Drilling Project Page 22

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