ULNRC-05893, Callaway, Unit 1, Enclosure 39 to ULNRC-05893 - Burns & Mcdonnell (Burns and Mcdonnell Engineering Company) 2008. Phase Ii Hydrogeologic Investigation Report Collector Well Siting Study, Callaway Unit 2. June (Part 1 of 3)

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Callaway, Unit 1, Enclosure 39 to ULNRC-05893 - Burns & Mcdonnell (Burns and Mcdonnell Engineering Company) 2008. Phase Ii Hydrogeologic Investigation Report Collector Well Siting Study, Callaway Unit 2. June (Part 1 of 3)
ML12271A475
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Site: Callaway Ameren icon.png
Issue date: 06/30/2008
From: Higgins P J
Burns & McDonnell Engineering Co
To: Grothe T
Office of Nuclear Reactor Regulation, Ameren Corp, AmerenUE
References
ULNRC-05893
Download: ML12271A475 (49)
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Phase II Hydrogeologic Investigation Report Collector Well Siting Study prepared for Ameren Corporation Ameren-UE June 2008 Project No. 46691 prepared by Burns & McDonnell Engineering Company, Inc. Kansas City, Missouri COPYRIGHT© 2007 BURNS & McDONNELL ENGINEERING COMPANY, INC.

9400 Ward Parkway June 30, 2008 Jvlr. Tom Grothe Ameren-UE Callaway Plant PO Box 620 Fulton, MO 65251-0620 Phase II Hydrogeologic Investigation Report Collector Well Siting Study 466 91

Dear Jvlr. Grothe:

We are pleased to present the attached final report for Phases 1 and 2 of the hydrogeologic investigation addressing the suitability of the Missouri River alluvial aquifer for providing a groundwater supply source for the Callaway County plant. The Phase 1 report, prev i ously submitted as a draft for your review, is also mcluded as Appendix A of the Phase 2 report Phase 1 consisted of test drilling at seven locations and was completed in order to select the most appropriate sites for more detailed hydrogeologic mvestigation as part of Phase 2. Phase 2 consisted of aquifer pumping tests at two locations, both of which demonstrated the suitability of those sites for potential collector well locations.

The Phase 2 report includes a description of the investigations performed, data collection and analysis, an estimate of collector well yields, and conceptual design for a typical collector well. As always, Bums & McDonnell apprectates the opportunity to be of serv i ce to UE. Please do not hesitate to contact me (816-822-3887, phigg@bumsmcd.com) or Dave Stous (816-822-3088, dstous@bumsmcd.com) ifyou have any comments or questions.

Sincerely, Patrick J. Higgins, R.G. Project Manager Kansas City, Missouri 64114-3319 Tel: 816 333-9400 Fax: 816 333-3690 http.llwww.burnsmcd.com Chapter Number ES 1 2 3 4 5 6 7 Appendix A Appendix B Appendix C AppendixD AppendixE INDEX AND CERTIFICATION Phase II Hydrogeologic Investigation Report Collector Well Siting Study Ameren Corporation Project 46691 Report Index Chapter Title Executive Summary Introduction Test Well and Observation Well Installation Aquifer Testing Procedures Aqu1fer Testing Activities Investigation Results Conclusions and Recommendations References Phase 1 Investigation Report Geologic Logs Water Quality Laboratory Analysis Report Pumping Test Analysis Calculations Projected Collector Well Yield Estimate Certification Number of Pages 2 1 3 2 2 10 1 1 102 15 139 27 8 I hereby certify, as a Professional Engineer in the state ofMissouri, that the information in the document was assembled under my direct personal charge. This report is not intended or represented to be suitable for reuse by the Ameren-UE or others without specific verification or adaptation by the Engmeer. This certification is made m accordance with the provisions of the laws and rules of the State of Missouri under Missouri Administrative Code_ Oc--vD.

BMcD, David Stous, P.E., P_Q_ Date: JvVLe. 30 * )-(.)() 8 (Reproductions are not valid unless signed, dated, and embossed with Engineer's seal)

Phase II Hydrogeologic Investigation Report Table of Contents TABLE OF CONTENTS Page No. EXECUTIVE

SUMMARY

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

1

1.0 INTRODUCTION

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

1-1 2.0 TEST WELL AND OBSERVATION WELL INSTALLATION

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

  • 2-1 3.0 AQUIFER TESTING PROCEDURES

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

3-1 3.1 Background Data

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

3-1 3.2 Step Tests .........................................................................................................................

3-1 3.3 Constant-Rate Tests .........................................................................................................

3-1 3.4 Water Quality Sampling ..................................................................................................

3-2 4.0 AQUIFER TESTING ACTIVITIES

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

4-1 4.1 Well TW-01 Testing ........................................................................................................

4-1 4.2 Well TW -02 Testing ........................................................................................................

4-1 5.0 INVESTIGATION RESULTS .............................................................................

5-1 5.1 Observation Well and Test Well Construction

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

5-1 5.2 Background Data

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

5-1 5.3 Step-Rate Tests ................................................................................................................

5-2 5.4 72-Hour Constant-Rate Tests ...........................................................................................

5-2 5.5 Analysis ............................................................................................................................

5-3 5.6 Estimated Collector Well Yield .......................................................................................

5-5 5. 7 Water Quality ...................................................................................................................

5-7 5. 8 Conceptual Design ...........................................................................................................

5-9 5.9 Water Rights ..................................................................................................................

5-10

6.0 CONCLUSION

S AND RECOMMENDATIONS

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

S-1

7.0 REFERENCES

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

7-1 APPENDIX A -PHASE I INVESTIGATION REPORT APPENDIX B -GEOLOGIC LOGS APPENDIX C-WATER QUALITY LABORATORY ANALYSIS REPORT APPENDIX D -PUMPING TEST ANALYSIS CALCULATIONS APPENDIX E-PROJECTED COLLECTOR WELL YIELD ESTIMATE * * * *

  • TOC-1 'Ameren Phase II Hydrogeologic Investigation Report Table of Contents LIST OF TABLES Table No. Page No. ES.1 Design Yield ..................................................................................................................

ES-1 ES.2 Design Water Quality ....................................................................................................

ES-2 2.1 Well Construction Information Summary .......................................................................

2-2 5.1 Step Test Data Summary .................................................................................................

5-2 5.2 Aquifer Analysis Results .................................................................................................

5-4 5.3 Aquifer Hydraulic Characteristics Summary ...................................................................

5-5 5.4 Collector Well Design Parameters

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

5-6 5.5 Design Yield ....................................................................................................................

5-6 5.6 Field Parameter Data ........................................................................................................

5-7 5.7 Laboratory Analysis Results Summary ...........................................................................

5-8 5.8 Collector Well Preliminary Design ..................................................................................

5-9 LIST OF FIGURES Figure No. Figure 1 ...............................................................................................................

Investigation Area Figure 2 , ............................................................................................

Test Well TW-01 Site Layout Figure 3 ............................................................................................

Test Well TW-02 Site Layout Figure 4 ...................................................................................................

TW-01 Site Cross Section Figure 5 ...................................................................................................

TW-02 Site Cross Section Figure 6 ........................................................................... Missouri River & Aquifer Water Levels Figure 7 .............................................................

TW-01 Constant Rate Test Observation Well Data Figure 8 .............................................................

TW-02 Constant Rate Test Observation Well Data Figure 9 ............................................................................

Test Well TW-01 Groundwater Contours Figure 10 ..........................................................................

Test Well TW-02 Groundwater Contours Figure ll ................................................................

Estimated Collector Well Yield Callaway Plant Figure 12 ......................................................

Preliminary Collector Well Design Ameren Callaway * * * *

  • TOC-2 'Ameren Phase II Hydrogeologic Investigation Report Executive Summary EXECUTIVE

SUMMARY

The pnmary purpose of this Phase II Hydrogeologic Investlgatwn effort IS to confirm that the hydrogeologic characteristics of the Missouri River alluvial aquifer near the Callaway Plant will support the installation of collector wells that will supply the quantity and quality of water needed for Callaway.

This effort included test hole drilling, the performance of two, 72-hour aquifer pumping tests, water quality analysis, and analysis of the pumpmg test data to estimate well capacity and develop a conceptual design. The tests indicated that aquifer conditions at both sites are very suitable for the installation of high capacity collector wells. While both test sites were suitable, Ameren has recently negotiated the purchase of the property around the TW-01 site. Smce the aquifer testmg results mdicate that this site can supply the necessary volume of water, our results will concentrate on this site. The estimated well yield at site TW-01 is shown below: Table ES 1 Design Yield Average summer Test conditwns Average winter 37 MGD (26,000 gpm) 32 MGD (22,000 gpm) 25 MGD (17 ,000 gpm) Because of the large potential yield capacity, our proposed conceptual well design consists of a 20-foot mside diameter concrete caisson constructed to bedrock and fourteen 200-foot laterals mstalled m two tiers. Bums & McDonnell recommends the construction of three such collector wells to provide a makeup water supply of approximately 50,000 gpm for two units at the Callaway Nuclear Plant. The analysis mdicates water supply from the collector wells could be 85 percent river water and 15 percent aquifer water during most of the year. During winter months with cold river water, there may be a larger percentage of aquifer water. Based upon water samples from the river and the aquifer, the design water supply from the collector wells would be as shown below. In reviewing the following it is important to understand that actual water chemistry will vary from the design water chemistry.

The design water chemistry is a hypothetical analysis that serves as a design tool. ES-1 Phase II Hydrogeologic Investigation Report Table ES 2 Design Water Quality Constituents Design Cations Calcium, ppm 72.32 Magnesium, ppm 22.90 Potassium, ppm 5.89 Sodium, ppm 50.60 Anions Chloride, ppm 10.03 Fluoride, ppm 0.50 Nitrate, ppm as Nitrogen 4.29 Silica, ppm 14.22 Miscellaneous Iron, ppb 1,304.51 Manganese, ppb 136.44 pH 7.95 Executive Summary Range 69.10 75.54 22.42 23.38 5.78 6.00 48.40 52.81 9.03 11.04 0.50 0.51 3.86 4.72 13.35 15.10 882.82 1,726.21 97.20 175.68 7.91 7.99 Based upon the aquifer flow parameters and the design water analysis, water treatment is likely to be required during well development.

Initially high iron concentrations are expected to decline with time as river water is drawn through the river bed and replaces the native aquifer water. Burns & McDonnell is in the process of performing water chemistry tasks that will1dentify w1th greater certamty the type and quantity of water treatment that may be required.

These results will be addressed separately from this report. ***** ES-2 Phase II Hydrogeologic Investigation Report Introduction

1.0 INTRODUCTION

Ameren Corporation (Ameren) IS prepanng a Combmed License ApplicatiOn (COLA) for submittal to the Nuclear Regulatory CommissiOn for the construction and operation of a second umt at the Callaway Nuclear Plant in Callaway County, Missouri.

As part of the COLA, a hydrogeologic investigation is being completed to evaluate the possibility of using horizontal collector wells to supply the cooling water for the existing and proposed units. Bums & McDonnell Is pleased to provide tlus report to address the methods, analysis, and conclusions related to Phase II of the hydrogeologic investigation for the proposed collector wells along the Missouri River. All figures and appendices referenced in the text are presented at the end of this report. During Phase I of the hydrogeologic investigation, seven test borings were advanced to bedrock in order to determme the depth, approximate saturated thickness, and geologic composition of the of the Missouri River alluvium near the existing surface water intake that currently supplies cooling water to Unit 1. Monitoring wells were installed at each boring location to obtain static water level observations and to allow measurement of water levels during aquifer pumping tests to be conducted as part of Phase II of the proJect. Water quality samples were obtamed from these monitonng wells m August of 2007. Locatwns of the monitoring wells are shown in Figure 1 and labeled FMW-06 through FMW-12. Geologic logs and a geologic cross section through the investigation area are included in the Phase I Investigation Report, mcluded m this report as Appendix A. Data including depth to bedrock and grain size of the geologic material obtained from Phase I test drilling was used dunng Phase II to select two test well locations (TW-01 Site & TW-02 Site) and to design the test wells. The locations of the aquifer test sites are presented in Figure 1 Eighteen observation wells were also installed (nine at each test well Site) to obtain additional data used to analyze the aquifer flow characteristics.

A 72-hour constant-rate aquifer pumping test was completed at each site to estimate the potential yield of a collector well. * * * *

  • 1-1 Phase II Hydrogeologic Investigation Report Test Well and Observation Well Installation 2.0 TEST WELL AND OBSERVATION WELL INSTALLATION Drilhng for Phase II was performed between October 1 and November 12, 2007. During Phase II, a total of two test wells (TW-01 & TW-02) and 18 test borings were drilled at the test Sites shown in Figure 1. Selected Phase II activities including drilling and construction of both test wells were observed by a Burns & McDonnell geologist.

All of the drilling activities were observed by a Bums & McDonnell archeologist to verify that no cultural resources were disturbed dunng the mvestigation.

Cahoy Well & Pump Service (Cahoy) of Fredericksburg, Iowa completed all test well and observatwn well drilling.

At each Site, a test well and six observation wells were drilled to bedrock. Two shallow observation wells were installed to a depth of approximately 50 feet below grade (tbg) and one bedrock observation well was installed 40 feet into the bedrock unit below the alluvial aquifer to monitor the vertical flow and mteractwn between the alluvial and bedrock aquifers.

Figures 2 and 3 are plan VIews showing the layout of the wells at the TW-01 and TW-02 Sites, respectively.

Each boring location was first drilled from 0 to 20 fbg with 1 0-inch diameter hollow stem augers and sampled with a Central Mine Eqmpment (CME) continuous sampler, so that any evidence of cultural resources would be clearly visible. After the first 20 feet were drilled with hollow stem augers, temporary surface casing was set and the well was drilled to total depth using reverse rotary or direct rotary methods. Cahoy completed all observation well drilhng using hollow stem auger and mud rotary techniques.

Each observation well was constructed with 20 feet of 2-inch diameter, Schedule 40 machine-slotted (0.010-mch) PVC screen set at the bottom and completed with solid Schedule 40 PVC casing to the ground surface. A gravel pack was placed alongside the screen extending up to a depth of approximately 5 to 10 feet above the top of screen, and a minimum 3-foot thick bentonite chip seal was placed above the gravel pack. A bentonite slurry grout was then pumped in to fill the borehole to grade. Borehole total depths ranged from approximately 52 to 138 tbg. All wells were registered with and approved by Missouri Department of Natural Resources.

Following construction, each observation well was developed by air lifting to remove drilling fluid from the area around the well screen and to enhance communication between the well screen and the aqmfer. A summary of the well construction mformation is mcluded as Table 2.1. 2-1 Phase II Hydrogeologic Investigation Report Test Well and Observation Well Installation Table 2.1 Well Construction Information Summary Well No. : Diameter ! Drilled Depth: Top ofScreen : Bottom ofScreen TW-01 --12--r 95 -l 54 r - 64

.. ******

OB01-03 OB01-04 OB02-01

___________

, .. , ... , ... ,, ...........................

2 99 79 99 ----------------***** ------------...:-----

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

***** ... ------------------

2 96 76 l 96 l 2 :I -----98 ---------75--1:"'--__ 95 2 _,_ ...... 97 ... ---2 . 52 30 50 '"'"'"'"'"'"'"'"'""'"'"'"'""'""'""""""'"'"'"""""""'""'

"""'"'"'"""'""""'"'"'

___ ,,, ...............................

_,,_, __ ,,,,,,,.,, ....................

.. 12 95 6 97 50 74 r* 137* 90 94

'2''"'i'"'''97'""":----77---*

                        • 97'"'

OB02-03 2 . _ 2 _J OB02-05 : 2 ' OB02-06 2 . ----';*-96 . 76 ..... *-9] ... *:::I __ 77 98 97 . 77 74 -;----2 OB02-S1 I 52 30 OB02-S2 . 2 52 30 ___ :r *.*.*

  • j3s**** * :::1--118 I ' ..........

____ ':__ _____ _ 96 97 97 94 ' 50 I I 50 i 138 -.-----------_L *OBOl-Bl was completed as an open borehole (without screen and gravel pack) durin ITV-0 1 testin . At each test well location, Cahoy drilled a 24-inch diameter borehole to bedrock using reverse rotary techmques.

A test well was then constructed of 12-mch diameter steel casmg with 40 feet of continuous wire-wrap steel screen with 0.020-inch openings.

A gravel pack was placed alongside the screen extending up to a depth of approximately 5 to 10 feet above the top of screen, and a minimum 3-foot thick bentonite chip seal was placed above the gravel pack. A cement grout was then pumped m to fill the borehole to grade. Following construction, the test well was developed by air lifting, bailing, surging, and then pumping with a submersible pump. This development procedure continued until the well water was observed to be clean after starting and stopping the pump several times. Total well development time was approximately 13.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> for TW-01 and 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> for TW-02. Geologic logs for the test wells are included in Appendix B. 2-2 Phase II Hydrogeologic Investigation Report Test Well and Observation Well Installation A field survey was conducted at each Site. Burns & McDonnell personnel used a surveying level to determme the elevation of the top of casing of each test well and observation well in relation to an arbitrary Site datum. ***** 2-3 Phase II Hydrogeologic Investigation Report Aquifer Testing Procedures 3.0 AQUIFER TESTING PROCEDURES 3.1 BACKGROUND DATA Aquifer and Missoun R1ver levels were monitored throughout the mvestlgatwn to evaluate the hydraulic connection between the river and the aquifer, and to observe any water level trends during the pumping tests that might impact the analysis and results. A Level TROLL 700 data logger was installed in monitoring well FMW-1 0. FMW-1 0 is located approximately halfway between the two Sites, and well beyond the radius of influence of the pumping wells. Data collected from th1s well was used to evaluate changes m the aquifer water level that were not associated with the pumping activities in the two wells. The LevelTROLL recorded groundwater level data every 15 minutes from October 2 to November 28, 2007. 3.2 STEP TESTS Step-rate pumping tests were conducted on both test wells using a submersible pump in order to determine the efficiency of the test wells and to determine the pumping rate for each constant-rate test. The flow rate was measured using a free discharge orifice weir (10-inch pipe, 8-inch orifice) fitted with a manometer tube. The discharge from the test well flowed overland to the Missouri R1ver. The step tests consisted of four or five steps in which the pumping rate increased with each subsequent step. Durmg each step the well was pumped at a constant-rate until the pumpmg water level became relatively stable. Water levels in the test well were recorded by Cahoy personnel throughout the step tests. At each Site substantial measures were taken to minimize the potential for erosion from the discharge.

3.3 CONSTANT-RATE TESTS Following the step-rate testing, water levels in the aquifer were allowed to recover for a minimum of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> before a 72-hour constant-rate test was mitiated. During each constant-rate test, water levels were monitored manually in the test well using an electric water level meter. Water levels m the observation wells were constantly measured with pressure transducers and recorded at regular intervals using Situ, Inc. Hermit 3000 and LevelTROLL 700 computerized data recorders.

Manual measurements were also collected at intervals with an electric water-level meter as a backup to the electronic instruments.

The flow rate was monitored manually and with a pressure transducer connected to the Hermit 3000. Changes in barometric pressure were monitored and recorded by the Hermit 3000. The Vi'Ameren 3-1 Phase II Hydrogeologic Investigation Report Aquifer Testing Procedures Missouri River stage was monitored with an In-Situ, Inc. Level TROLL 500, set in a stilling well in the river near each test Site. After 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of pumping the wells were shut down and the aquifer water level recovery was monitored.

Each test well and the observation wells were monitored in the same manner as during the pumping portion of the test. The nver stage was also monitored dunng the recovery portiOn of the test. 3.4 WATER QUALITY SAMPLING Water quality samples were collected from the discharge of the pumpmg well at three intervals during the constant-rate test in order to evaluate changes m the water quality over time. Temperature, conductivity, and pH of the discharge were measured at the beginning, middle and end of the test. For companson, temperature measurements were collected in the Missouri River. Samples were collected 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, and 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br /> after pump start-up.

Sample analysis results are attached as Appendix C of this report. Vi" Ameren * * * *

  • 3-2 Phase II Hydrogeologic Investigation Report Aquifer Testing Activities 4.0 AQUIFER TESTING ACTIVITIES 4.1 WELL TW-01 TESTING TW-01 was step tested on November 7, 2007. Four steps were completed, at 797, 1205, 1580, and 1691 gallons per minute (gpm ). Results of the step-rate test mdica ted that the highest pumping rate that could reliably be sustained for 72-hours in TW-01 was approximately 1600 gpm. Therefore a pumping rate of approximately 1600 gpm was selected for the 72-hour constant rate test. The 72-hour constant-rate pumping test on TW-01 was started at 8:00a.m. on November 8, 2007. TW-01 was pumped at a constant-rate of 1594 gpm with only mmor fluctuations until 8:00a.m. on November 11, when the pump was shut down and the recovery portwn of the test began. Recovery was momtored until 8:00a.m. on November 12. Durmg the test, the Missour1 River stage dropped approx1mately 0.8 feet, wh1ch dewatered the stilling well and the LevelTROLL 500 which was monitoring the river stage. The river level dropped below the pressure transducer at approximately 2:00p.m. on November 8. The LevelTROLL 500 was reinstalled in the stilling well at a greater depth at 12:15 p.m. on November 9, and adjustments were made to the data to correct for the change in the level of the transducer.

Water quality samples were collected at three mtervals durmg the constant-rate test. The first sample was collected at 10:30 a.m. on November 8, the second at 1:00 p.m. on November 9, and the third at 7:00a.m. on November 11. Each of the samples was stored on ice and either delivered by Bums & McDonnell personnel or shipped to the laboratory for analysis.

4.2 WELL TW-02 TESTING A step test was completed on TW-02 on November 3, 2007. Five steps were completed, at 797, 1205, 15 80, 2021, and 2044 gallons per minute (gpm). Results of the step-rate test indicated that a continuous pumping rate of approximately 1900 gpm could be sustained for the 72-hour constant-rate pumping test at TW-02. The 72-hour constant-rate pumpmg test on TW-01 was started at 8:00a.m. on November 14, 2007. TW -02 was pumped at a constant-rate of 1906 gpm with only m mor fluctuations until 8 :00 a.m. on November 17, when the pump was shut down and the recovery portion of the test began. Recovery was monitored until3 :30 p.m. on November 17. Vi'Ameren 4-1 Phase II Hydrogeologic Investigation Report Aquifer Testing Activities Water quality samples were collected at three intervals during the constant-rate test. The first sample was collected at 10:30 a.m. on November 8, the second at 3:10p.m. on November 9, and the th1rd at 7:25a.m. on November 11. Each ofthe samples was stored on ice and either delivered by Bums & McDonnell personnel or shipped to the laboratory for analysis. Vi" Ameren * * * *

  • 4-2 Phase II Hydrogeologic Investigation Report Investigation Results 5.0 INVESTIGATION RESULTS The followmg paragraphs describe the analysis of the observatiOn well and test well constructiOn data and the results of the aquifer testing completed at the site. 5.1 OBSERVATION WELL AND TEST WELL CONSTRUCTION The materials encountered in the test borings at the site were Missouri River alluvium consisting of a generally coarsening-downward sequence of inter-bedded layers of fine to coarse sand. The upper 10 feet of the formation is a mixture of silt, clay and sand that transitions to fine to medium grained sand. From approximately 10-60 fbg, the formatiOn IS pnmarily sand with some gravel. The lower 40 feet of the formation is a poorly sorted mixture of sand and gravel with some cobbles. Based on the visual observations during drilling and geophysical logs from Phase L there were no significant layers or lenses of fine-grained materials that could potentially restrict groundwater flow encountered in any test boring at depths greater than 30 fbg. Bedrock underlymg the sand and gravel consists of dolomite and was encountered at depths ranging from 95 to 99 fbg. Groundwater was measured at each Site prior to starting any test pumping activities and averaged approximately 20 fbg. The saturated thickness of the aquifer is approximately 75 to 80 feet. A generalized geologic profile along the line of the test borings for the TW-01 Site is presented in Figure 4, and for TW-02 Site m Figure 5. 5.2 BACKGROUND DATA The Missouri River was monitored using the USGS gages at Booneville and Jefferson City. In addition, a Level TROLL 500 was installed in a stilling well in the river adjacent to each test Site for the duration of each pumping test. Figure 6 is a graph showing the groundwater level data collected from FMW-10, the Missouri River data from the USGS gage at Jefferson City and the local river data for each test. Aquifer water levels monitored in FMW-1 0 indicate a good hydraulic connection to the Missouri River and rapid response to changes in the river stage. The Jefferson City gage data indicates that the Missouri River stage declined approximately 0.8 feet during the TW-01 test and approximately 0.4 feet during the TW -02 test. Aqmfer water levels at FMW -10 durmg those same penods declined approximately
0. 7 feet and 0.4 feet, respectively. W Ameren 5-1 Phase II Hydrogeologic Investigation Report Investigation Results 5.3 STEP-RATE TESTS Step-rate tests were completed in each test well as described above. Results of the step tests were used to calculate the specific capacity (pumping rate div1ded by draw down) of each test well m order to determme the appropriate flow rate for the constant-rate pumping test. Specific capacity and drawdown for each step are presented in Table 5.1 Table 5.1 Step Test Data Summary Test Well TW-01 Test Well TW-02 Q Specific Q Specific Step Drawdown Capacity Step Draw down Capacity No. (gpm) (feet) (gpm/ft) No. (gpm) (feet) (gpm/ft) 1 797 14.56 54.7 1 825 33.11 24.9 2 1205 22.67 53.2 2 1205 38.00 31.7 3 1580 33.10 47.7 3 1609 42.20 38.1 4 1691 37.00 45.7 4 2021 48.20 41.9 5 2044 48.45 42.2 5.4 72-HOUR CONSTANT-RATE TESTS Two 72-hour constant-rate pumping tests were completed as described in the previous section. Due to the decline in the Missouri River Level, the aquifer static water level also declined.

This decline is apparent m the observation well water level data and results m the appearance of mcreased draw down. The data from the observation wells was corrected for the drop in aquifer water level by subtracting the value of the decline in the aquifer water level at FMW-1 0 at a given time from the observation well data at that same time. Graphs of the recorded water level data corrected for the decline in the river and aquifer water levels durmg the TW-01 test are presented m Figure 7, and for TW-02 m Figure 8. In general, water levels recorded electronically closely match those recorded manually.

Gage data from the USGS stream gage in Jefferson City correlated well with the Site stage measurements.

Drawdown contours at the TW-01 Site from the end of the 72-hour test are presented in Figure 9 and for the TW-02 Site in Figure 10. W Ameren 5-2 Phase II Hydrogeologic Investigation Report Investigation Results 5.5 ANALYSIS Transmissivity is defined as the rate at which water is transmitted through a unit width of aquifer under a unit hydrauhc gradient.

Storativity, also known as the storage coefficient, is the volume of water an aquifer releases or takes into storage per unit surface area of the aquifer per unit change m head. The distance to the line source of recharge is a computational method for considering infiltration from an adJacent nver or lake. It simplifies calculations of mfiltratwn of nver water through an area of streambed by assuming the recharge is from a line at a distance "a" from the pumping well. The "a" distance is a parameter used in the estimate of collector well yield. Calculations of "a" are based on image well theory developed by Theis. For this analysis, data IS recorded from two lines of observation wells, one parallel to the river and one perpendicular to the river. Aquifer parameters of transmiSSivity (T) and storativity (S) were calculated from pumpmg test data usmg computational methods developed by Theis (1935), Cooper and Jacob (1946), Neuman (1972, 1974), and Rorabaugh (1956). In general, time-drawdown analyses (Theis, Neuman) will give better indications of aquifer conditions near the pumping well and distance-drawdown analyses (Cooper and Jacob) give better mdicatwns of conditwns near the edge of the cone of depresswn.

Additwnally, the distance to the line source of recharge "a" was calculated using methods developed by Rorabaugh.

Results of the calculations ofT and S are presented m Table 5.2. Pumpmg test data and calculations are presented in Appendix D. Usmg the Rorabaugh method, the apparent "a" distance along the hne of observatwn wells parallel to the river for the TW-01 Site under test conditions is approximately 1000 feet. The apparent "a" along the perpendicular line of observation wells for the TW-02 Site is approximately 825 feet. This difference indicates varying transmissivity in the area of the test, which is confirmed by the varying depth to bedrock and varymg estimates of transmissivity from the tlme-drawdown analyses at the mdividual observatwn wells. W Ameren 5-3 Phase II Hydrogeologic Investigation Report Investigation Results Well Nos. OB01-01 to -06 OB01-01 ,-05,-06 OB01-02,-03 Test Elapsed Time 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 48 hours 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Test Elapsed Time 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 48 hours 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Table 5.2 Aquifer Analysis Results Time-Drawdown Analysis Test Well TW-01 Test Well TW-02 Average Average Transmissivity Storage Transmissivity Storage (gpd/ft) 548,300 489,400 500,000 (unitless)

Well Nos. 0.0129 OB02-01 to -06 0.0071 OB02-0 1,-05,-06 0.0267 OB02-02,-03 Distance-Drawdown Analysis Line of Wells Parallel to River Test Well TW-01 Test Well TW-02 (gpd/ft) 632,800 562,500 550,600 Transmissivity Storage Test Elapsed Transmissivity (gpd/ft) 466,000 464,900 462,500 (unitless)

Time 0.155 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 0.215 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> 0.262 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Distance-Drawdown Analysis Line of Wells Perpendicular to River Test Well TW-01 Test Well TW-02 (gpd/ft) 363,900 372,400 375,500 Transmissivity Storage Test Elapsed Transmissivity (gpd/ft) (unitless)

Time (gpd/ft) 426,200 0.118 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 426,100 429,500 0.152 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> 431,000 436,000 0.169 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 434,000 (unitless) 0.0007 0.0009 0.0005 Storage (unitless) 0.155 0.282 0.417 Storage (unitless) 0.190 0.203 0.482 Because there is some variation in apparent hydraulic conditions at the test Sites, conservative values were selected for considering collector well yield estimates.

These values are summarized in Table 5.3. W Ameren 5-4 Phase II Hydrogeologic Investigation Report Investigation Results Table 5.3 Aquifer Hydraulic Characteristics Summary Transmissivity Distance to Line Source of Recharge Saturated Thickness Hydraulic Conductivity (K) Storativity (S) TW-01 Site 450,000 gpd/ft 1000 feet 78 feet 5770 gpd/ff 0.179 5.6 ESTIMATED COLLECTOR WELL YIELD TW-02 Site 400,000 gpd/ft 825 feet 77 feet 5195 gpd/ff 0.208 Estimates of potential collector well yield were made using methodology developed by Hantush and Papadopulos (1962). The method considers the theoretical drawdown under steady-state pumping conditions in a collector well located adjacent to a river and constructed in an unconfined aquifer. In addition to aquifer parameters determined from the pumping test, potential collector well yield is also dependent on several design and seasonal river factors. These include available drawdown, river level and water temperature.

The river level will impact the amount of water that will flow from the river to the subsurface and mfluence the static water level. Temperature will 1m pact the v1scosity of water moving through the river bed and aquifer. A 1-degree Fahrenheit change m water temperature will change the effective permeability of the aquifer by 1 Yz percent. The average June to August water temperature of the Missouri River at Hermann, Missouri is approximately 77° F and the average winter water temperature is approximately 40° F. Groundwater temperatures will moderate the temperature of the water moving through the river bed to the collector well. The effective value of transmissivity will change due to changes in viscosity at varying water temperatures which will impact calculations of the distance to the line of recharge and estimates of well yield. Des1gn parameters and assumptwns for seasonal yield are listed in Table 5.4. W Ameren 5-5 Phase II Hydrogeologic Investigation Report Investigation Results Table 5.4 Collector Well Design Parameters Summer Winter Conditions Test Conditions Low Flow Flow Grade, ft. msl (from USGS topo map) 520 +/- 520 +/- 520 +/- I op of Sand, ft. m sl 510 510 510 Base of Aquifer, ft. msl 422 422 422 Centerline of Upper Tier of Laterals, ft. m sl 434 434 434 Inside Diameter of Caisson 20 20 20 Saturated Thickness 76 77 76 Static Water Level, ft. msl 498 499 498 Hydraulic Conductivity, gpd/fe 5770 6710 4950 (temperature corrected)

Radius of Lateral, ft. 0.5 0.5 0.5 Design Distance to Line Source of Recharge, ft 1000 900 1200 Average Lateral Length, ft. 200 200 200 Number of Laterals 14 14 14 Aquifer Water T emperature , op 57 68 45 M i nimum Design Pumping Level, ft. msl 444 444 444 Calculated yield and drawdown for test, summer and winter conditions are shown in Figure 11. Yield calculations are presented in Appendix E and the calculated maximum yields for each set of seasonal conditwns are summanzed m Table 5.5. Table 5.5 Design Yield Average Summer I est conditions Average winter 37 MGD (26,000 gpm) 32 MGD (22,000 gpm) 25 MGD (17,000 gpm) Due to the vanability of the aqmfer matenals, actual yield of a collector well may be higher or lower depending on materials encountered during installation of the collector well laterals.

Analysis of the pumpmg test data mdicates that the Missoun River alluvium at both of the test well sites is capable of providing the necessary yield for a large capacity collector well. Both the Missouri River and the groundwater aquifer will contribute water to a well. Initially, a higher percentage of water will come from the aquifer, but as the pumping duration increases more water will infiltrate from the river. Usmg the test well data, it IS estimated that when steady-state conditwns develop, approximately 85 percent of the water pumped will come from induced infiltration of river water and 15 percent will be groundwater originating as infiltration of precipitation through the upper soil horizons (Appendix E). The actual percentage of nver/aquifer water will also vary with season due to changmg water temperature, W Ameren 5-6 Phase II Hydrogeologic Investigation Report Investigation Results river stage, and aquifer water levels. Current knowledge of riverbed infiltration characteristics indicate that the ratio of river water to aquifer water content will be highest in the summer and lowest in the wmter. Actual river/aquifer percentages will depend on several factors including:

  • Distance from the well to the river
  • Duratwn of pumpmg
  • Geology of the subsurface sediments impacted by pumping (radius of influence will be larger than dunng the test pumpmg)
  • Changing water temperature of the river, resulting in changing permeability of the river bed 5. 7 WATER QUALITY During the 72-hour pumping test, the temperature, conductivity, and pH of the discharge were measured at the begmning, middle and end of the test. For comparison, temperature measurements were collected m the Missoun River. Table 5.6 summarizes the field parameter data from the two tests. The field parameter data was collected for verification, but as expected there was not much variation in the results. Although the Missouri River alluvium at the Sites is highly transmissive, at these test rates and durations the River's mfluence on the field parameters was negligible.

Table 5.6 Field Parameter Data Sample Time Temperature Conductivity Well No. (after test start) pH (OF) (JlS) TW-01 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 6.9 58.8 1000 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> 7.0 58.4 1000 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br /> 6.9 58.1 1010 TW-02 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 7.1 57.5 760 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> 7.1 58.0 740 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br /> 7.4 58.0 730 Discharge samples were collected at three intervals during each test to evaluate the quality of water for the proposed use by Ameren. The samples were placed m a cooler with tee and shtpped to Pace Analytical Laboratories, Inc. in Lenexa, Kansas for analysis.

Selected parameter results from the laboratory analyses are presented in Table 5.7. The results indicate that with the exception of dissolved tron, the levels of the constituents analyzed are withm typical ranges found m groundwater from alluvtal aquifers in the area. Laboratory reports are included in Appendix C. W Ameren 5-7 Phase II Hydrogeologic Investigation Report Table 5.7 Laboratory Analysis Results Summary Constituents Alkalinity, ppm as CaC03 Aluminum, ppb Ammonia, ppm as N Arsenic, ppb Barium, ppb Beryllium, ppb Bicarbonate, ppm Cadmium, ppb Calcium, ppm Carbon dioxide, ppm Carbonate, ppm Chloride, ppm Chromium, ppb Cobalt, ppb COD, ppm Copper, ppb Fluoride, ppm Hardness, ppm as CaC03 Iron, ppb Lead, ppb Magnesium, ppm Manganese, ppb Mercury, ppb Molybdenum, ppb Nickel, ppb Nitrate, ppm as Nitrogen Nitrite, ppm as Nitrogen Nitrogen, ppm Noncarbonate hardness, ppm as CaCO Orthophosphate, ppm pH Phosphorus, ppm Potassium, ppm Selenium, ppb Silica, ppm Silver, ppb Sodium, ppm Specific conductance, f.JS/cm Strontium, ppb Sulfate, ppm TDS, ppm TOG, ppm TSS, ppm Turbidity, NTU Zinc, ppb W Ameren Design Range 259.62 245.93 19.91 17.91 0.19 0.17 2.81 2.53 379.28 339.52 0.49 0.44 259.62 245.93 2.11 1.90 72.32 69.10 3.46 3.11 4.34 3.90 10.03 9.03 2.44 2.19 2.52 2.27 27.36 24.63 3.35 3.01 0.50 0.50 225.64 221.66 1,304.51 882.82 13.42 12.08 22.9D 22.42 136.44 97.20 0.96 0.87 10.00 9.00 2.35 2.11 4.29 3.86 0.03 0.03 2.53 2.28 56.56 53.23 0.29 0.27 7.95 7.91 0.33 0.30 5.89 5.78 2.07 1.86 14.22 13.35 0.80 0.72 50.60 48.40 722.30 718.89 531.79 521.94 148.02 141.21 560.79 559.25 13.37 12.71 17.33 15.60 109.34 109.25 14.42 12.97 5-8 Investigation Results 273.31 21.90 0.21 3.09 419.03 0.54 273.31 2.32 75.54 3.80 4.77 11.04 2.68 2.77 30.10 3.68 0.51 229.61 1,726.21 14.77 23.38 175.68 1.06 11.00 2.58 4.72 0.03 2.78 59.89 0.32 7.99 0.36 6.00 2.27 15.10 0.88 52.81 725.72 541.63 154.84 562.33 14.03 19.07 109.43 15.86 Phase II Hydrogeologic Investigation Report Investigation Results 5.8 CONCEPTUAL DESIGN During the course of this study, Ameren successfully negotiated the purchase of the property that the TW-01 site iS located on. While the aqmfer charactenshcs at both sites were acceptable for constructmg capacity collector wells, the right-of-way and property access issues are now significantly reduced at this site. For this reason, the conceptual design is directed towards constructing the wells on the TW-01 site. The results of the test drilling and aqmfer testmg mdicate that a collector well capable of yielding approximately 17,000 to 26,000 gpm can be developed at the TW-01location.

The transmissivity of the aquifer at the site is estimated to be 450,000 gpd/ft. The preliminary design recommendations for collector wells at this site to meet the expected plant demand are listed m Table 5.8 and shown m Figure 12. Table 5.8 Collector Well Preliminary Design Caisson mside diameter, feet Catsson outside diameter, feet Total length of caisson (below grade), feet Total length of caisson (above grade), feet Number of laterals (2 tiers, 7 laterals per tier) Centerline of upper tier of laterals (below grade), feet Minimum Length of laterals (each) Screen, feet Blank, feet Lateral Diameter, inches Screen Entrance Velocity, ft/mm Screen Slot Size (estimated), mches Minimum distance between caissons, feet 20 25 100 23 14 92 190 10 12 < 2.0 0.10* 1500 *Screen slot size will vwy according to data collected during installation of the laterals.

The top of the caisson should extend to above the 500-year flood elevation of 543, which is about 23 to 24 feet above grade at this location.

Laterals should extend 200 feet from the caisson, if possible.

The screens should be of stainless steel, wire-wrapped construction.

This design allows a large open area per lineal foot of screen permitting low water entrance velocity, which will help reduce screen fouling. The estimated amount of open area for each collector well screen iS 1.32 ft2/linear foot. Assummg 14 laterals with 190 feet of screen each (10 feet of blank near the caisson) and the amount of open area, the mechanical capacity of the proposed collector well would be approximately 26,000 gpm. W Ameren 5-9 Phase II Hydrogeologic Investigation Report Investigation Results Mechanical capacity is the maximum quantity of water that can pass through the well screens at a velocity of 2.0 feet per mmute, assummg a 50% blockage of the screen open area. The mechamcal capacity should be greater than the estimated aquifer yield to allow slow entrance velocity during standard operation, which should help to prolong periods between well maintenance.

This number will vary with actual lateral length and slot s1ze mstalled.

The 14 laterals should be placed in 2 tiers and spaced within a 225-degree arc generally facing the Missouri River (see Figure 12). 5.9 WATER RIGHTS Water rights are not needed in Missouri.

However, large water users are required to report yearly usage to the Missoun Department of Natural Resources. W Ameren ***** 5-10 Phase II Hydrogeologic Investigation Report Conclusions and Recommendations

6.0 CONCLUSION

S AND RECOMMENDATIONS A water supply from honzontal collector wells can be developed at the Site to provide the estlmated plant demand of 50,000 gpm. Based on the design conditions, three wells will be required to meet this demand. However, due to the variability of the aquifer materials, the actual yield of a collector well may be higher or lower depending on materials encountered during installation of the collector well laterals.

Based on the levels of total dissolved solids, the water will likely not require treatment prior to use by the plant. Treatment of the water supply from the collector wells may be required to reduce iron concentratwns present m the supply. It IS anticipated that the Iron concentrations from the collector well field will reduce over time and may eventually not require any treatment before use at the plant. W Ameren ***** 6-1 Phase II Hydrogeologic Investigation Report References

7.0 REFERENCES

Cooper, H.H. and C.E. Jacob, 1946. A generalized graph1cal method for evaluating formatwn constants and summarizing well field history, Am. Geophys. Union Trans., vol. 27, pp. 526-534. Neuman, S.P., 1972. Theory of flow in unconfined aquifers considering delayed gravity response of the water table, Water Resources Research, vol. 8, no. 4, pp. 1 031-1045.

Neuman, S.P., 1974. Effect of partial penetration on flow in unconfined aquifers considering delayed gravity response, Water Resources Research, vol. 10, no. 2, pp. 303-312. Rorabaugh, M.J., 1953. Graphical and theoretical analysis of step-draw down test of artesian wells, Proc. of the Am. Soc. Civil Eng., vol. 79, separate no. 362, 23p. Theis, C.V., 1935. The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using groundwater storage, Am. Geophys. Union Trans., vol. 16, pp. 519-524. Walton, W.C., 1970. Groundwater Resource Evaluation,McGraw-Hill Series in Water Resources and Environmental Engmeering, McGraw-Hill, Inc., 664p. W Ameren * * * *

  • 7-1 FIGURES

COPYRIGHT 0 2007 BURNS & McDONNELL ENGINEERING COMPANY, INC. I APPROX 250 FEET TO RIVER @ FMW-07

  • OTW-01 01 005 0oo 0 75' N 02 52 SCALE IN FEET 15[]' 0oa 0o4 LEGEND 0 TESTWELL 0 06 OBSERVATION WELL & NUMBER FMW-07
  • EXISTING OBSERVATION WELL INSTALLED IN 2007 FIGURE2 TEST WELL TW-01 SITE LAYOUT COPYRIGHT C 2007 BURNS a McDONNELL ENGINEERING COMPANY, INC. I APPROX 50 FEET TO RIVER FMW-11 0
  • OTW-02 01 ls1 0os 0os 75' SCALE IN FEET 00s2 02 150' 0o3 004 LEGEND Q TESTWELL 0 06 OBSERVATION WELL & NUMBER FMW-11. EXISTING OBSERVATION WELL INSTALLED IN 2007 FIGURES TEST WELL TW-02 SITE LAYOUT COPYRIGHT 0 2007 BURNS & McDONNELL ENGINEERING COMPANY, INC. 10 20 30 40 50 l:i:wTO 110 100 110 120 no 140 150 NORTH OB01-S1 0801-04 0801-03 OB0 1-520801-Q2 0801-06 TW-01 0001-01 FMW-07 0601-81 0801*06 -'*' *' ... *. \ .. . . . ' .... ?'. ::. :.* :* *::::-** . .. .. * .. . .. * * * * . ... . * . * . . * . *..*. '.
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  • OB01-Il1 0001-03. 0801-52_ JlB01..()2 TW-0 1& FMW.07
  • TO MISSOURI RIVER ' APPROX. 260FT. 0 125'
  • SCALE IN FEET II m ; SILT&CLAY FINE SAND FINE TO MEDIUM SAND . MEDIUM SAND COARSE SAND BEDROCK FIGURE4 TW-01 SITE CROSS SECTION COPYRIGHT 0 2007 BURNS & McDONNELL ENGINEERING COMPANY, INC. 0 10 20 30 40 50 il=l="ljl)

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__ 6 I 4 10/15/07 10/22/07 10/29/07 11/5/07 11/12/07 11/19/07 11/26/07 12/3/07 Figure 6 Missouri River & Aquifer Water Levels River Aquifer Data.grf 1/4/08

-1 0 L.. 2-"E 1 ro..::l ...... (/) J::O: _,_.o a..w Q).c oE-2 TW-01 Constant Rate Test --FMW-07 0801-01 ; I -I -0801-03 _, 1 --0801-04 ---0801-05 3 4 I I I I I I -1000 -500 0 TW-01 Complete Corrected.grf 12/19/07 I I I I I I I I I I I I I I I I I 0801-06 --0801-81 --0B01-S2 *,_ I I I I I I I, I I I I I 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Elapsed Time (min) Figure 7 TW-01 Constant Rate Test Observation Well Data L.. _,_.E -2 0 ro..::l 2 ...... (/) J::O: _,_.o a..w Q).c oE-4 6 J I I I I I I -1000 -500 TW02 Complete Corrected.grf 6110108 1'-r" --1-----* -TW-02 Constant Rate Test ---FMW-07 ---0801-01 -0801-02 ---0801-03 ----0801-04 --0801-05 -0801-06 --0801-S1 ----0801-S2 ' I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I J I I ' I I I 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 Elapsed Time (min)....---------r--------------1 Figure 8 TW-02 Constant Rate Test Observation Well Data COPYRIGHT C 2007 BURNS & McDONNEll ENGINEERING COMPANY, INC. / I I I I j I I \ \ \ I I I / \ \ \ \ '\ / / -.,... ----------.........

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  • EXISTING OBSERVATION WELL INSTALLED IN 2007 '-.. 0oe _ 29.99 DEPTH TO GROUNDWATER FROM SITE DATUM '<? ... -27*87 ---__.-__. GROUNDWATER LEVEL ISOCONTOUR LINE FIGURES TEST WELL TW-01 GROUNDWATER CONTOURS ..._@ ---DASHED WHERE INFERRED --------------------

N 0 75' 150' SCALE IN FEET COPYRIGHT C 2007 BURNS & McDONNEll ENGINEERING COMPANY, INC. 1----------------------------------

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' --' -' 0os __ ...... LEGEND @ ' --' --....... --....... -------------0 75' 150' SCALE IN FEET 0 TESTWELL 0 06 OBSERVATION WELL & NUMBER FMW-11. EXISTING OBSERVATION WELL INSTALLED IN 2007 29.99 DEPTH TO GROUNDWATER FROM SITE DATUM __./ GROUNDWATER LEVEL ISOCONTOUR LINE DASHED WHERE INFERRED FIGURE 10 TEST WELL TW-02 GROUNDWATER CONTOURS 0 10 20 ? 30 Q) Q) LL ..._.. 40 0 "0 $: 0 50 60 70 80 CWyield.grf 117108 .........

........ Drawdown limit LEGEND Summer Low Flow Conditions

Test Conditions -----Winter Average Conditions

........ ' ' \ -...........

--\ \ \ \ " ' ' \ --------1 Centerline of Upper Tier of

__ 0 5000 10000 15000 Discharge (MGD) 20000 25000 30000 Figure 11 Estimated Collector Well Yield Callaway Plant PUMP STATION EL 543'+/- __/ II 25'-0" II : 20'-0" .. EXISTING AND FINISH 9 Cr:i Cll I EL 520'+/- "' z 0 ,,..1 0 LLJ ....1 a:l 5 ;;: +I <o (0 20'1 DEPTH TO WATER "'---I-10' (MINIMUM WATER ELEVATION) 5' 0 G) V :-**.-**;.-.;.***:\J I , EL 422'+/- *.: '* *. ,, ._ BEDROCK 7' SECTION 17\ NOT TO SCALE \_:_) NOTES: (D ADDITIONAL SPARE PORTS TO BE LOCATED BY CONTRACTOR.

10 FEET BLANK SECTION MEASURED FROM INSIDE FACE OF CAISSON. @ MINIMUM DESIGN LENGTH OF EACH LATERAL IS 200 FEET FROM INSIDE FACE OF CAISSON. LINE PERPENDICULAR TO RIVER BANK J?i I I 25'-0" WELl. PLAN VIEW 0 4' 8' SCALE IN FEET 12' Figure 12 PRELIMINARY COLLECTOR WELL DESIGN AMEREN CALLAWAY APPENDIX A PHASE I INVESTIGATION REPORT

-. 0 . . 9400 Ward Parkway Date: September 6, 2007 To: Tom Grothe-Ameren Corporation From: Pat Higgins, Paul McCormick Re: Phase I Test Drilling at Callaway Nuclear Plant, Callaway County, Missouri Ameren Corporation (Ameren) is preparing a Combined License Application (COLA) for submittal to the Nuclear Regulatory Commission for the construction and operation of a second unit at the Callaway Nuclear Generating Station in Callaway County, Missouri.

As part of the COLA, a hydrogeologic investigation is being completed to evaluate the possibility of using horizontal collector wells to supply the cooling water for the ex i sting and proposed units. During Phase I of the hydrogeologic investigation, seven test borings were advanced to bedrock in order to determine the depth and approximate saturated thickness of the Missouri River alluvial aquifer near the existing surface water intake that currently supplies cooling water to unit number 1. Monitoring wells were installed at each boring location to obtain static water level observations, water quality samples, and allow measurement of water levels during aquifer pump i ng tests, to be conducted during Phase 2 ofthe pro j ect. Loca ti ons of the monito ri ng wells are shown m Figure 1 and labeled FMW-06 through FMW-12. Presented in this memo are the methods, findings, and conclusions related to Phase 1 of the hydrogeologic investigation.

Test Drilling and Well Construction Procedures Prior to drilling, the boring sites were evaluated by MACTEC to determine if any cultural resources or wetlands would be impacted.

A surface electromagnetic survey was performed at each boring site. If the electromagnetic survey indicated the potential for Kansas City, Missouri 64114-3319 Tel: 816 333-9400 Fax: 816 333-3690 www. bumsmcd. com

-\ . September 5, 2007 Page2 buned artifacts, a MACTEC archaeologtst was present during drilhng to examine the cutt i ngs and ensure that no cultural resources were disturbed.

No ev i dence of cultural resources were identified in borings FMW -06 through FMW -12. Seven test borings were drilled in July and August of 2007 and completed as monitoring wells. The test boring locations are shown in Figure 1 as FMW-06 through FMW-12. Aquadrill, Inc. of Swisher, Iowa completed all drilling and well construction work using hollow stem auger and mud rotary drilling techntques, under the direct i on of Paul C. Rizzo Associates, Inc. of Pittsburg, Pennsylvania.

A Burns & McDonnell geologist was present at the site to observe the fieldwork and prepare drilling logs for each boring. Each boring was drilled from 0 to 20 feet below grade (fbg) with 10-inch diameter hollow stem augers and sampled with a CME continuous sampler, so that any evidence of cultural resources would be clearly visible. After the first 20 feet were drilled with hollow stem augers, temporary surface casmg was set and a 6-mch diameter borehole was drilled to bedrock using mud rotary methods. The geology was logged by a Burns & McDonnell geologist based on the drill cuttings collected from each five-foot interval.

Drilling logs for each boring are presented in Attachment 1 Subsequently, geophysical logging consisting of natural gamma, spontaneous potential, and single point resistivity methods was completed in each borehole.

The geophysical logs for each boring are presented in Attachment

2. Grain-size distribution analysis was performed on four representative samples of aquifer materials collected from each of the test borings by Alpha-Omega Geotech of Kansas City, Kansas. Results of the grain size analyses for each boring are presented in Attachment
3. Each test boring was completed as a monitoring well with a steel protective cover. Each monitoring well was constructed with 20 feet of 2-inch diameter, Schedule 40 slotted (0.010-mch)

PVC screen set at the bottom and completed with solid Schedule 40 September 5, 2007 Page3 PVC casmg to the ground surface. A gravel pack was placed alongside the screen extending up to a depth of approxtmately 5 to 10 feet above the top of screen, and a minimum 3-foot thick bentonite chip seal was placed above the gravel pack. A bentonite slurry grout was then pumped in to fill the borehole to grade. FMW-12 was completed with an above-ground protective casing, and the remaining wells were completed with flush-mounted steel protective manhole cover. A concrete pad approximately two feet square was them poured around the protective casing .. Following construction, the monitoring wells were developed by surging, air-lifting, and pumping the well to remove drilling fluid from the area around the well screen and enhance communication between the well and the aquifer. Development was completed in two sessions at each well. Each well was airlifted, disinfected with chlorine and allowed to sit overnight.

The next day the well was airlifted again until the well water was observed to be reasonably clean a short time after startmg the pump. Investigation Results The materials encountered in the test borings at the site were Missouri River alluvium consisting of inter-bedded layers of fine to coarse sand from approximately 10-60 fbg, underlain by approximately 40 feet of fine to coarse grained sand with some fine gravel. Based on the visual observations during drilling and the geophysical logging, clay layers were not encountered in any test boring at depths greater than 26 fbg. Bedrock underlying the sand and gravel consists of dolomite and was encountered at depths ranging from 95 to 10 1. 5 fb g. Groundwater was encountered in each boring at a depth of approximately 12 fbg. The saturated thickness of the aquifer is approximately 83 to 90 feet. Figure 2 is a cross section through the aquifer developed using the data from the seven test holes and FMW-1 D and FSB-03. The cross sectwn in dicates that the aquifer

-\ . September 5, 2007 Page4 material in the study area 1s coarsest near FMW -07 and FMW -06. A larger proportion of fine gra i ned mater i als is found at the west end of the study area near FMW-11 and at the east end of the study area near FMW -12. Each borehole was logged using geophysical methods to assist in identifying and locating any layers of fme-grained materials (silt and clay) that might be present in the subsurface.

Geophysical logging consisted of natural gamma, spontaneous potential, and single-point resistivity methods. Both the geophys i cal logging and the vtsual observations of the samples during drilling confirmed that there are not significant layers of fines present at depths greater than 40 fbg. The grain-size distribution analyses also support this conclusion, indicating an average of 1.4 percent fines (material smaller than 200-mesh sieve) in any ofthe samples, with a range of 0.3 to 3.7 %. Groundwater samples were collected from the monitoring wells on August 22, 2007. The samples were submitted to Pace Laboratories for analysts.

The results of the analysis will be used for permitting and design in the event that it is decided to move forward with the construction of horizontal collector wells. Analysis ofthe samples is currently in progress.

Conclusions and Recommendations The anticipated water supply demand for each unit is approximately 25,000 gallons per minute or 36 million gallons per day. Phase 1 testing continues to indicate that this demand can potentially be obtained from two or three horizontal collector wells. Grain size analyses and observation of the saturated aquifer thickness indicate that the Missouri River alluvial aquifer in the study area is likely suitable for development of a series of collector wells capable of meeting the plant's water supply requirement.

-\ . September 5, 2007 Page 5 Two pumping tests are recommended for Phase 2, i n order to better evaluate the aquifer characteristics and estimate the yield of a series of horizontal collector wells in the study area. Several ofthe borings had to be moved because the property owners denied access to their property.

As a result, several of the borings (FMW -11 and FMW -12) are substantially farther from the other borings than originally planned. Two tests are necessary due to the distance between the borings and the variations in the grain-sizes throughout the study area. Phase 2 will consist of the installation of two test pumping wells (each capable of yielding 1,000 to 1,500 gallons per minute to sufficiently stress the aquifer), and nine additional piezometers at each site. A 72-hour pumping test will be performed at each test well location.

The first test well is proposed to be installed at the site of monitoring well FMW-07. Based on visual observation and grain-size analysis this location had the coarsest material m the study area. The second test well i s proposed to be installed near FMW -11, wh i ch had a higher proportion of finer-gramed sands. Mter complet i on of the testing activities, the test wells and piezometers will be abandoned in accordance with Missouri Department of Natural Resources regulations.

If you have any questions or comments regarding these investigations, please do not hesitate to contact us.

-. FIGURES

A vtY v v & Fll.tW-010 FMW-11 FSB-03 FMW-10 10 " " . . " 50 " I <) *. " 0.. :; 0 u i I " ii: UJ w z 00 UJ ...J ...J w 100 0 c o1l 110 ;;;;) Ill s 0 "' @ .... :1: Q FMW-00 FMW-08 0 1600' SCALE IN FEET NORTH FMW-07 3200' -FMW-06 date FIGURE 2* CROSS SECTION A' FMW-12 SILT&Cl.AV 0 D D FII>IETO MEDIUM SAN::l ME'DIUMSAND MEDIUM TO COARSE SAND [] COARSE SAND BEDROCK projed. 46691 controct CALLAWAY d"ll*""* -* 2

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